Transactions of an international conference. Worldwide concern: better dental care for more people. An international collaborative study. How social surveys were conducted. It is assumed that utilization of dental care services and hence the state of oral health is dependent on social and psychological characteristics of both consumers and providers. The sociological variables studied included the basic facts of age, sex, residence and socioeconomic status. Attitudes to general health care, past oral health care and self assessment of oral health status were also investigated. Accessibility of oral health care facilities in terms of cost, loss of time and distance travelled was assessed, as was the consumers estimate of the dentist's sensitivity and competence, his attitude to preventive care, aesthetic values and knowledge of oral health care measures. Sociologists from the participating countries cooperated in the formulation of questionnaires which could be applied with comparable results despite differences in language and culture. Adults were interviewed in their own homes while younger groups completed the questionnaire in school under the supervision of the researchers. In all cases the sociological survey preceded the clinical examination to reduce the introduction of bias. The data were collected in Geneva and analysed to determine the extent to which oral health status could be related to perception of need, personal oral health practices, availability, accessibility, acceptability and utilization of services. Further analysis may help to determine whether observed differences between populations relate more to the characteristics of the systems of dental care or to features inherent in the population of the country.


Transactions of an international conference. Worldwide concern: better dental care for more people. An international collaborative study. How the oral and social measures were compared. This paper explains the statistical methods used to reach the conclusions regarding the relationship between selected social variables and oral health status reported in subsequent papers referring to specific countries. The procedure called 'stepwise regression' was employed in relation to each of the three clinical categories of data. The single social variable which explains the greatest variation in the oral data is identified as the most important predictor. Its influence is then removed by mathematical adjustment and the second and subsequent social variables are similarly identified until no further ones remain which are significant in explaining remaining variability in the oral data. The effect of utilization was always removed first regardless of its predictive power. The findings for each country were used to construct 'tree' diagrams on which the best and worst pathways are indicated to give a profile of those subjects having the fewest and the most decayed teeth.


Oral health care in Australia.

Oral health care in Australia. The study data on oral health status for this age group was consistent with previous recent studies. The sociological data added considerably to the knowledge of the charactistics of this group in the area sampled in New South Wales, Australia. The system of delivery of oral health services mainly through private practice appears to be providing comprehensive treatment to a segment of the student population fairly well defined by sociological variables reported in the analysis. However, only limited services appear to be reaching sizeable remainder.


Oral health care for Canterbury, New Zealand 13-14 year old students. The study has demonstrated a high prevalence of dental caries and a uniformly high level of treatment across all major population groups of Canterbury 13-14 year olds. The treatment programme has the problem of dental caries under control but more attention should be directed to lowering caries prevalence and the need for treatment by increased use of preventive measures. While increasing the population coverage in respect of fluoridated water would give the greatest reduction in caries prevalence, alternatives should be considered, especially in areas not served by piped water supplies. As dental personnel appear to be important sources of health education information, advantage should be taken of this opportunity to emphasize the importance of preventive care. The early signs of periodontal disease are of concern and they, too, should be susceptible to a more concerted preventive programme. Previous studies have demonstrated a high prevalence of denture wearers amongst New Zealand adults. This, and these early results from the International Collaborative Study have focussed attention on the need for information on factors influencing the demand for treatment once adolescents have reached the maximum age covered by the Government programmes. Further investigation is needed to provide these data.


Features of oral health care across cultures. This paper sets out to draw together the findings from the five individual studies and to draw tentative conclusions from them. It is pointed out that the comparisons made are between system factors and not between whole systems of oral health care. An attempt is made to evaluate the effectiveness of individual system features in the hope of being able to suggest ways in which those shown to be most beneficial might be incorporated into complete systems. In relation to caries experience, measured as DMF teeth, there is a wide variation, not only by each of the separate components to that total. In those studies where extensive school dental services exist, the F component accounts for almost all the score while in the other study groups it forms only about half the total, the proportion tending to be greater in the non-metropolitan than in metropolitan populations. In the same way treatment/need ratios and amounts of retreatment required show the benefits of the existence of the school dental service. The treatment/need ratio is then examined in relation to selected variables such as method of payment, utilization of auxiliaries, the existence of specified target groups etc. When the method of stepwise regression analysis is applied to the pooled samples utilization of services remains the most important predictor of treatment/need ratio. Others in order of importance are whether dental personnel decide on frequency of visits, whether the last visit was made for symptomatic reasons alone and whether lack of severity of symptoms had been a reason for avoiding oral health care. In relation to periodontal conditions no clear picture has emerged and this may demonstrate how systems of all types have failed to deal with this problem. Although much remains to be elaborated three main findings have already emerged from this study: (i) The need for reinforcement of preventive behaviour and services. (ii) The effectiveness of regulated contact between consumer and provider in meeting treatment needs. (iii) The need to concentrate on quality as well as volume of care in providing adequately for the needs of child and adolescent populations.


Osteosarcoma: A review of 345 cases.

Osteosarcoma: A review of 345 cases. 345 cases of osteosarcoma are reviewed. The long term results are known in 240. The overall ten year survival rate was 5 per cent. This is analysed in relation to age, site of tumour, radiographic grading, and method of treatment. There were no survivors in patients under the age of fifteen; in tumours of the proximal half of the femur and humerus; or tumours of the trunk. If these cases are excluded, amputation gave a ten year survival rate in 11 per cent. The radiographic grading expressed in relation to expansion of the tumour has a significant relationship to the prognosis. In the authors' experience histological grading of the tumour is not feasible and probably has no bearing on the prognosis. The authors express their preference for treatment based on their analysis of this series.


Isolation of Haemophilus aphrophilus from an adult with acute leukemia. During the course of treatment for acute myelocytic leukemia, Haemophilus aphrophilus was isolated from eight blood cultures associated with the clinical picture of bacterial endocarditis.


The histology of eclamptic lesions.

The histology of eclamptic lesions. A brief description is given of the main lesion found in eclampsia. Emphasis is placed on the marked difference between the type of lesion found in the kidney and those found in other organs. It is suggested that they may be explained on the basis of increased coagulability of the blood, hypertension and possibly increased permeability of blood vessels. Hypertension may damage vessels and determine the sites of thrombus deposition. Increased permeabilithe mesangium of the glomerulus.


Genital mycoplasmal infections: their relation to prematurity and other abnormalities of reproduction. The genital mycoplasmas, Mycoplasma hominis and Ureaplasma urealyticum eT-mycoplasmas) are common vaginal organisms. They are acquired primarily through sexual contact. There is evidence, some of it highly suggestive, linking the genital mycoplasmas to involuntary infertility, spontaneous abortion and low birth weight. Additional controlled treatment studies are needed in each of these areas to assess fully the role of the genital mycoplasmas. M. hominis has the potential to invade the blood stream and is responsible for some instances of fever following abortion and of postpartum fever.


An evaluation of proximal surface cleansing agents. The effectiveness of the Interspace brush, Inter-Dens, and waxed dental floss as proximal surface cleansing agents was compared in 35 subjects. Each subject used all three methods of cleansing in random order of selection. Statistical analysis of the results showed that there was no difference in the effectiveness of any one of these three agents. However, proximal surfaces of anterior teeth where cleaned more effectively than posterior teeth. The coronal half of the proximal surfaces was cleaned more effectively than the apical half and the facial half more effectively than the lingual half when Inter-Dens was used. Comparison of cleansing effectiveness between facial and lingual halves of proximal surfaces for the Interspace brush and waxed dental floss showed no significant difference. Mesial and distal proximal surfaces were cleaned with similar effectiveness. Plaque control was only satisfactory on approximately half of the proximal surfaces, though a wide variation occurred. Significantly lower plaque scores were found 1 week after the initial instruction session, irrespective of the agent used. The majority of subjects preferred Inter-Dens whilst waxed dental floss was the least-liked method of cleansing.


Plaque-removing effect of a toothbrush, dental floss, and a toothpick. The ability of three different oral hygiene devices to remove 2-day-old bacterial deposits was evaluated on 21 young adults with healthy periodontia. On buccal tooth surfaces, the cleaning effect of a multitufted nylon brush was superior to that of a wooden toothpick or unwaxed dental floss. On lingual surfaces, the toothpick was as effective as the brush. On the visible portions of proximal surfaces, all three devices were equally efficient. A combined cleaning exercise with all three instruments together yielded significantly better results than did the use of each single device. Eight subjects were able to remove all disclosable deposits.


Use of palatal mucosa and lyophilized dura mater to create attached gingiva. Gingival extension procedures using free palatal mucosal autografts or homologous lyophilized dura were compared clinically. Palatal mucosa was transplanted in 68 cases and lyophilized dura in 16 cases. The width of the zone of attached gingiva was measured before surgery and at regular intervals up to 2 years postoperatively. The width of the attached gingiva remained relatively constant in the mucosal transplant group from 1 month postoperatively, with an average relapse of about 20%. In the dura group the width of attached gingiva showed a marked decrease until 3 months after surgery with an average relapse of approximately 63%. If a preset minimal width of the attached gingiva is considered to be the criterion of success, the superiority of the palatal mucosa grafting procedure is demonstrated.


The periodontal management of a patient with a profound immunodeficiency disorder. A case of severe, uncontrolled periodontal disease in a patient with a profound immunodeficiency disorder is reported. The periodontal disease was noted before the age of 10 years and is generalized, with marked associated alveolar bone loss, even threatening a mandibular fracture. Severely involved teeth were allowed to exfoliate, and extractions were avoided. At the age of 17 years, the patient now has only nine remaining teeth. The management adopted and alternative approaches are critically reviewed. The implications of the dental findings for current concepts of the pathogenesis of periodontal disease and dental caries are discussed.


Specification test for the solubility and disintegration of dental cements: a critical evaluation of its meaning. The specification test for solubility and disintegration is an essential screening test for the quality control of certain cement types. No cement fails it can be considered for use; however, the test has only a limited clinical significance because it does not give an indication of the stability of the fully hardened cement matrix either in oral fluids or water. Instead, it gives a measure of the content of the soluble reaction intermediate present in cements that are still hardening and where the matrix has not fully formed. The test relates, therefore, to early vulnerability to aqueous attack and hardening rate. The period of test is, in fact, an atypical one and the true extent of the erosion of the cement matrix is obscured by the presence of soluble reaction intermediates. Long-term extrapolations cannot be made and so test results for broadly satisfactory cements within a category cannot be used for valid comparisons of clinical excellence, and they can be used even less to compare different cement types with different setting reactions. For example, in general, the dental silicate cement has a higher solubility and distinegration figure than the zinc phosphate cement because it contains soluble sodium salt and hardens more slowly. However, it is more stable under oral conditiont an indication of the vulnerability of the forming matrix to attack. The test is not valid when applied to zinc oxide-eugenol cements because the products of decomposition are either virtually water-insoluble or volatile and therefore not measured under the conditions of the test. A method is suggested for overcoming this deficiency. The test needs to be supplemented by other tests done on fully hardened cements for longer periods of time and in mediums that can represent oral conditions. One example would be to stimulate acid conditions developed in stagnation areas. A total estimation of decomposition products, both soluble and insoluble, is called for rather than the determination of soluble materials only.


Diffusion of water in composite filling materials. The uptake of water by composite filling materials seems to be a diffusion-controlled process; the magnitudes of the diffusion coefficients obtained are consistent with the uptake base through the resin matrix. The diffusion coefficients measured show the diffusion coefficient to decrease with increasing water concentration, which accounts for the protracted nature of the attainment of equilibrium uptake. Diffusion coefficients are generally lower in these composites based on difunctional methacrylates, compared with methyl methacrylate, presumably because of the highly cross-linked nature of the former.


Enamel silicon and fluoride relationships demonstrating a surface silicon effect that facilitates fluoride uptake. This study indicated that a clear relationship exists between silicon and fluoride. We have also demonstrated a probable surface enamel silicon effect that increases fluoride uptake. The complex set of relationships described in the surface chemistry of calcium, tin, and zirconium with fluoride, hydroxide, phosphate, and other surface-occurring ions need not be considered to confuse the specific silicon-fluoride relationship presented here because in this computation we are relating the changes in the silicon and fluoride ion values only. We have, however, considered the thermodynamics of such reactions and intend to elaborate on it in a later publication. We are aware of the small depth of fluoride penetration into enamel after topical treatment Health Foundation, Research Unit at the National Bureau of Standards, Washington, DC 20034, USA.


Stress analysis of porous rooted dental implants. A model based on a continuously bonded interface predicts high punching stresses at the apex of the implant and low stresses in the cortical plates. A model based on a continuously bonded interface predicts high stiffness and a resultant low implant displacement-load ratio. A model based on a tissue ingrowth-bonded interface predicts uniform distribution of stresses around the implant through the cortical plates. A model based on a tissue ingrowth-bonded interface predicts an implant displacement-load ratio close to the ratio measured with actual implant specimens.


Load-extension-time behavior of orthodontic Alastiks. Typical elastomeric behavior displayed by Alastik orthodontic bands resulted in load-extension curves that depended on the rate of extension as well as the amount of extension. Initially, the modules tested at the faster speeds had higher moduli and were stronger; but as extension continued, the trend reversed, and at breakage the more slowly stretched modules were the strongest. Therefore, although the Alastiks appear to be uniformly produced, the clinician still needs to know his rate of deformation and degree of stretching to accurately assess the module force. In addition, the module, once in position, will not maintain a constant force but will experience a decrease in applied load with time kept at a constant extension. Because the initial load decay is more rapid for both faster extension and higher load, it seems reasonable to suggest that care be taken by the clinican to stretch the module more slowly into place. This should result in a higher load level for a longer period of time. Although the measured changes in loads are not necessarily of sufficient magnitude to seriously influence the clinical result, a clearer understanding of the module behavior, such as currently presented, will hopefully assist in more comprehensive clinical evaluations.


Effects of sodium trimetaphosphate supplementation of a high sucrose diet on the microbial and biochemical composition of four-day plaque and on urine calcium and phosphorus levels. Daily supplementation of a high sucrose diet with 5 gm TMP resulted in significant alterations in certain human plaque components. Veillonella and Neisseria population (as percent total viable microorganisms), S sanguis (as percent streptococci), and levan hydrolase activity per milligram of plaque increased, whereas total viable microorganisms per milligram of plaque, streptococci per milligram of plaque, and specific fructosyltransferase activity decreased during the TMP-containing diet regimen.


Enamel solubility rate measurements in vivo on naval recruits. Enamel solubility rates were determined in vivo to depths of 1 to 2 mum in the teeth from two samples of naval recruits that had been grouped, respectively, according to DMFT scores and visual indexes of oral hygiene status. No positive correlation between enamel solubility rates and DMFT scores were observed; rather there was a tendency for caries-resistant participants to have a highest apparent enamel solubility rates, even though mean differences among the DMFT groups were not generally significant. Intra-subject measurements on 12 teeth per participant for eight of the recruits showed, on the average, only about one half the variability founl incisors for more than 70 of the recruits. The least variability was found for measurements on paired maxillary central incisors. It was concluded that factors such as tooth morphology and, in particular, tooth-surface films could considerably affect enamel solubility rates measured in vivo.


Radiographic spatial frequencies essential to the diagnosis of incipient interproximal lesions. The effects of fixed pattern noise on the interpretation of dental radiographs containing known lesions suggest that reliable detection of incipient interproximal caries is influenced by the spatial frequency of information visibly displayed. Frequencies less than the limiting resolution of existinta also permit demonstration that significantly less resolution is required horizontally than vertically to achieve a criterion level of diagnostic accuracy. These findings are consistent with the notion that accurate diagnosis may be possible with less resolution than is currently produced by conventional bitewing radiographic techniques. If this is trut means for radiographically detecting caries can be developed that require less exposure of the patient to ionizing radiation.


Role of attrition and occlusal contact in the physiology of the rat incisor: X. The part played by the periodontal ligament in the eruptive process. Removal of the proliferating base of the rat incisor did not influence the rate of eruption which responded to changes in impediment to eruption in a fashion similar to that for control teeth. It is the peridontal ligament rather than the proliferating cells that is responsible for tooth eruption. The elements of the peridontal ligament apparently responsible for tooth movement are the mature fibroblasts.


Composition of fluoridated dental enamel studied by x-ray photoelectron spectroscopy (ESCA). A combination of ESCA and argon-ion etching has been shown to be effective in determining the surface and subsurface composition of dental enamel. The heavy organic coating on enamel has been investigated. Beneath this coating, untreated enamel was found to have invariant phosphorus and calcuim concentrations over the region surface. The surface of enamel treated with an acid phosphate-fluoride gel was shown to be almost entirely connected to calcium fluoride. A phosphate species, noncalcium and possibly a sodium salt, was found to be present in the surface layer. At a depth lower than about 60 nm, there was a gradual increase in phosphorus concentration that approached the value for untreated enamel with increasing depth. The increasing phosphorus and decreasing fluorine concentrations were primarily caused by the increasing concentration of unreacted hydroxyapatite. These results have shown that ESCA coupled with argon-ion etching, can be used effectively to examine the surface and subsurface composition of dental enamel. The surface sensitivity, ability to strip thin layers of material, sensitivity to low atomic weight elements, and ability to differentiate between different oxidation states makes a combination of these two techniques extremely useful for dental research.


Kinetics of calcium metabolism in rat dentin and enamel. The time course of the specific activity of 45Ca in the dentin and enamel of rat incisors and molars was followed after an intravenous injection of the radiotracer. It was then correlated with the specific activity of 45Ca in plasma to obtain the accretion rates on the dentin of molars and incisors. The exchangeable calcium pool sizes in the dentin and the enamel of the molar were also calculated.


Comparative anatomic study of mandibular growth in rats after bilateral resections of superficial masseter, posterior temporal, and anterior digastric muscles. Bilateral resections of the superficial masseter, posterior temporal, and anterior digastric muscles of rats were done to determine their effects on mandibular growth. The macroscopic findings support the functional matrix theory of mandibular growth. The analysis of body weight and the statistical two-way analysis of variance done suggest that malnutrition was the main factor that caused the mandibles of rats in the experimental groups of remain undersized.


Chromatographic properties of denatured skin and bone collagens on hydroxyapatite. Denatured collagen samples extracted from the skin and bone of lathyritic rats with guanidine hydrochloride were chromatographed on hydroxyapatite columns. A major fraction of the bone extract that was rich in alpha chain showed a stronger binding to hydroxyapatite when compared to the corresponding fraction from skin. Thus, bone collagen shows a special affinity for hydroxyapatite after isolation and denaturation.


Mitotic activity in the oral epithelium of the albino rat. In groups of Wistar rats 3 and 12 months of age, colchicine and radioautography were used to assess mitotic activity in oral epitheliums. Apparent mitotic activity in the epitheliums of the cheek, hard palate, and central, intermediate, and lateral zones of the soft palate depended on the method used and the age of the rat.


Latex spheres as immunologic markers to demonstrate the binding of human salivary immunoglobulins to Streptococcus mutans. The results of this study indicate that latex beads can be used to identify specific antigen-antibody interactions on the surface of bacterial cells. The application of a Labelling Index allowed specific interactions to be quantitatively distinguished from non-specific latex bead attachments. The labeling indexes for latex beads absorbed to anti-salivary immunoglobulins were significantly higher than for negative control indexes when tested against S mutans treated with saliva. Conversely, there was no significant difference when they were tested against nonoral bacteria treated with saliva. This suggests that both whole and parotid human saliva contained specific antibodies against S mutans.


Influence of amalgam, alloy, and mercury on the in vitro growth of Streptococcus mutans: II. Comparison of amalgams and alloys. The influence of three alloys and their amalgams on the in vitro growth of Streptococcus mutans has been estimated. Spherical, fine cut, and dispersion alloys were studied. Dispersion alloy amalgams seem to inhibit bacterial growth more than amalgams prepared from the other alloys in a similar fashion.


Xylitol binding in human dental plaque.

Xylitol binding in human dental plaque. Human dental plaque and whole saliva sediment were tested for their ability to bind 14C-labeled sucrose, fructose, glucose, sorbitol, and xylitol. Sucrose, glucose, sorbitol, and fructose were bound to all materials tested, in this decreasing order. The binding was strongest with plaque given a five-second ultrasonic shock, and lowest with salivary sediment. Xylitol was only insignificantly bound, indicating that plaque microorganisms possess specific recognition sites for xylitol to a very restricted extent.


Glucose taste thresholds in cariesfree naval recruits. Glucose taste detection thresholds were determined in 41 cariesfree recruits and 53 recruits with caries experience. Cariesfree detection thresholds ranged from 5 to 45 mM/liter, with a mean of 13.4 +/- 1.7 whereas that of the control group ranged from 5 to 50 mM/liter with a mean of 22.3 +/- 1.7 (P less than 0.01). A Kilmogorov-Smirnov two-sample test demonstrated a significant difference in the distribution of thresholds between the two groups (P less than 0.01). These observations are in accordance with previous studies demonstrating that cariesfree recruits display lower sucrose taste detection thresholds than recruits with caries experience.


Effect of NaF pretreatments on the resistance of powdered human dentin to acid dissolution. The acid resistance of powdered human dentin increased linearly after pretreatments in 2.5, 25, 250, and 1,000 mM NaF in water. The acid resistance was not directly correlated to the F content of the dentin. The results indicated F uptake by the dentin to be a result of chemical reaction and of absorption.


Optical test for the groove adaptation of dental amalgams using a He-Ne laser. An optical test was developed for amalgam alloys by condensing amalgams against stain-less steel blocks with regularly spaced grooves forming diffraction gratings. The quality of the diffraction pattern obtained with a He-Na laser from these amalgams is a measure of the adaptation to the grooves.


DMBA and immunosuppression in the Syrian golden hamster. The immunosuppressive effects of topically applied 9, 10 dimethyl 1, 2 benzanthracene (DMBA) were investigated in the Syrian Golden hamster. Tri-weekly doses of DMBA were administered, with some hamsters receiving both DMBA and X-radiation. DMBA and DMBA-plus-radiation groups demonstrated decreased immune responsiveness relative to their control counterparts. Potential immunosuppressive effects of carcinogen and carcinoma are discussed.


The current status and impact of oral biology in dental education. Twenty-four oral biology departments were surveyed with respect to number of faculty, graduate programs, and role in the dental schools (ORB schools). The mean full-time and part-time faculty per department is eight and 2.6, respectively. There are nine graduate programs, but only one has actually granted Ph.D.'s in oral biology. Students of these ORB schools were compared with students of 32 dental schools which did not have oral biology departments (NOB schools) in performance on the dental National Board Examinations. With respect to mean scores, students from the ORB schools performed better on both part 1 and part 2 examinations from 1969 to 1974. There has also been an impressive difference in the failure rates, students in the ORB schools experiencing a lower failure rate. Further analysis demonstrated that oral biology departments have developed largely in dental schools which have relied upon medical school basic science departments for teaching the basic sciences.


A taxonomy for behavioral objectives in a dental school. This paper describes a taxonomy proposed for use by dental school faculties as an aid in specifying their course objectives in behavioral terms. This taxonomy, developed and tried at the Harvard School of Dental Medicine, is simpler than taxonomies previously proposed because it reduces the number of categories. In addition, the categories themselves are designed to communicate to and be interpreted by dental educators. The six categories are (1) knowledge of facts, concepts, and principles; (2) comprehension; (3) perceptual ability; (4) diagnosis and treatment planning skills; (5) motor skills; and (6) interactive skills. Each category is briefly defined and illustrated with two samples from operative dentistry.


Attitudes toward women dental students among male dental students and male dental faculty members. The results of this study support the following conclusions: 1. Male dental faculty and male dental students have similar perceptions of women enrolled in dental school. 2. Male dental faculty and male dental students rate women dental students high on the evaluative and activity scales of the semantic differential but relatively low in potency measures. 3. Male dental faculty and male dental students perceive women dental students as different from both the sex role of women and the professional role of dentist.


Time line analysis of dental restorative procedures related to dynamic instrument location. The detailed timing and recording of the sequence of tasks for dental restorative procedures was used to evaluate the effects of the location of the hand-piece and three-way syringe on the dental team performance. Sixty-four audiovisual tapes of ten dental teams, performing complete, actual restorative procedures, were made in two dental operatories that differed only in the location of the dentist's instrument cabinet. Total treatment sessions were divided into four major divisions and expressed as a percentage of the total time: patient preparation, 14%; tooth preparation, 32%; tooth restoration, 50%; and patient release, 4%. Tooth preparation and restoration took longer with the instruments in the 8-o'clock location than with them in the 12-o'clock location. When the teams were reversed, that is, changed to the other operatory, there was an increase in tooth preparation and restoration time. Instrument transfer and use, especially for the three-way syringe, tended to take longer for the 8-o'clock location. In contrast, the dentist's idle time tended to increase working with the 12-o'clock instrument location because of differences in work loads. Time line analysis provided a means of evaluating the impact of instrument location as well as an approach to assessing individual team performance.


Three-year clinical comparison of three amalgam alloy types emphasizing an appraisal of the evaluation methods used. Five different evaluation techniques were used to measure the marginal breakdown of three-year-old amalgam restorations. The most useful method appeared to be one in which photographs of all restorations were ranked in descending order starting with the restoration that had the least marginal breakdown and ending with the restoration that had the greatest deterioration. Three different alloys were evaluated and the results confirm those of previous studies; the alloy having the lowest creep was superior whereas restorations placed with the alloy having the highest creep displayed the greatest marginal breakdown.


Role of endodontics in current dental practice. The findings presented in this statistical study are applicable to a representative sample of dentists in general practice in Illinois. Almost 90% of the respondents in this survey do some or all of their root canal therapy. The majority of those who do some or all of their root canal therapy do so because they enjoy it. Most of the respondents (77.3%) do not take root canal cultures. Kerr's Root Canal Sealer is the most widely used sealer, followed by Kerr's Tubli-Seal and Dr. Wach's sealer, respectively. The preferred technique of filling root canals among the respondents is by means of guttapercha and lateral condensation for most canals and the use of silver points for narrow or constricted canals. A technique that is not taught in any American dental school, the Sargenti N2 technique, is used by almost 20% of the responding dentists. Most of the respondents try to fill the canal 0.5 to 1 mm from the apex. Although dozens of intracanal medicaments exist, the most commonly used one is camphorated parachlorophenol, which is used by more than 50% of the dentists who participated in this survey. A chelating agent is used by almost two fifths of the dentists surveyed and use of such an agent is increasing. More than half the respondents carry out some sort of endodontic surgery in their practice' apicoectomy is the most common endodontic surgery performed. The data show that 48.9% of the dentists who participated in this survey feel that dental schools should devote more time to teaching endodontics, 50.5% believe that the amount of time should remain the same, and only 0.5% feel that the amount of time should be decreased. About 70% of those who feel that the amount of time for teaching endodontics should be increased specified an increase in clinical training.


Accuracy of casts produced from alginate and hydrocolloid impression materials. It is recognized that alginate impression materials have been used to obtain casts from which castings have been fabricated for a number of years. This study indicates that more dimensionally accurate casts are produced from hydrocolloid compared with casts produced from alginate. The most accurate casts were produced from the polyether impression material.


Antibiotic prophylaxis for endocarditis in patients with a prosthetic heart valve. A review of the types of organisms and their sensitivities to antibiotics, as well as the source of infection, was carried out for 11 patients who had late onset infective endocarditis and a prosthetic heart valve. Candida organisms were isolated from two patients. In nine patients with late onset bacterial endocarditis, the organisms isolated were five streptococci and four staphylococci. Their sensitivities to antibiotics were penicillin, five of eight; erythromycin, eight of eight; and cephalothin, six of seven. Two patients with endocarditis had ulcerations beneath their dentures, and one had undergond a prior dental procedure. Of 52 healthy patients with prosthetic valves who were interviewed, only 18 had visited a dentist during the previous year, and six did not receive antibiotic prophylaxis for endocarditis. It is concluded that patients with prosthetic heart valves do not practice good oral hygiene and, if they do visit the dentist, some may not receive antibiotics for endocarditis prevention. An antibiotic regimen for endocarditis is presented that is consistent with the organisms found in the oral cavity and those found in patients with endocarditis who have a prosthetic valve.


Carcinoma of the nasopharynx and nasa fossa: report of case. A brief history of a case of nasopharyngeal carcinoma is described. A general discussion of the problems of diagnosis, treatment, and classification of the more frequent histologic type is presented. Currently, the most favorable prognosis is in patients in whom the condition is detected early. This serious disease sometimes occurs near or adjacent to the area of the dentist's primary responsibility. The dentist should always assume his professional responsibility by promptly referring any patient with suspected cancer to an appropriate specialist.


A study to develop a rating system and evaluate dental radiographs submitted to a third party carrier. An easy, efficient system for rating radiographs was developed and applied to 1,000 preauthorization case submissions. The films were evaluated and the frequency distribution of errors determined. Results showed the majority of the examined full-mouth and partial-mouth radiograph series submitted to Pennsylvania Blue Shield were substandard. Recommendations for screening radiographs to upgrade their technical quality are offered.


A combined approach to preventing dental caries in schoolchildren: caries reductions after one year. A prototype school-based dental program is being conducted in a low-middle-income, urban area, as a demonstration project to test the combined effect on dental caries of several preventive measures. Procedures include ingestion of fluoridated water (1.0 ppm), topical application of acidulated phosphate fluoride, application of a pit and fissure sealant, early detection of caries and restoration of affected teeth, and dental health education (oral hygiene and dietary counseling program). The four-year project began in early 1973. A group of 1,200 children in the first and sixth grades was randomly separated into a treatment and a comparison group. All children participate in a dental health education program and consume fluoridated water. Dental care is provided on site at 18 schools, with the use of two mobile vans, saving time and expense in school hours lost and transportation costs. A hygienist coordinates the oral hygiene and dietary programs in classrooms with the help of teachers trained in workshops. Supervised toothbrushing, flossing, and use of disclosing agents are carried on in the classrooms. First-year caries increment data in permanent teeth indicate a high degree of success. Occlusal surfaces of permanent teeth in children in the treatment group, contrasted to those in children in the comparison group, showed an average reduction in caries of 84%. The encouraging results obtained at the end of one year indicate that a school-based preventive dentistry program may have great potential for preventing and controlling dental caries in schoolchildren.


Survey of dentists on the impact of the United Auto Workers/auto industry dental plan. Survey responses showed little change in dental office staffing and paperwork as a result of the UAW/auto industry program. Only slight differences between respondents in the four states were apparent; except for Michigan, where the greatest increase in staff and additional clerical hours was reported. The differences that did exist might be related to the volume of UAW/auto industry business in each area and the dentists' opinions of the carriers they relate to most frequently. The responses did not reveal a clear indication of success or failure of the plan by virture of any category evaluated.


Two-year report of sealant effect on bacteria in dental caries. Teeth in which caries had penetrated the pits and fissures were sealed with an ultraviolet-light-polymerized sealant. Samples of carious dentin were taken from teeth that were not sealed and from teeth that were sealed, up to two years after the sealant had been placed. The major reduction in viable microorganisms occurred during the first two weeks, and there was a gradual reduction in the total count thereafter. At the end of two years, there was a 2,000-fold decrease in the number of cultivable microorganisms. Preliminary clinical and radiographic findings suggest that there was no progression of the carious lesions, but further studies are needed before this technique can be considered an alternative to conventional procedures.


Forensic dentistry.

Forensic dentistry. Data and information derived from the teeth and oral structures have been used successfully where other methods of identification or determination of criminal responsibility have failed. In many instances, the techniques used in forensic dentistry bring evidence to a point of certitude that would otherwise be lacking. Teeth, by their formation and structure and their relative permanence, record and retain the history of their development and the history of the incidents to which they have been subjected. Generally, the characteristics of formation and structure of teeth contribute information pertinent to probabilities of relationships and probabilities of events. As a result, these characteristics are highly useful in affirming or negating evidence as circumstantial or as factual.


Hypertension screening among dental patients. Between January 1974 and March 1975, blood pressures were taken on all 2,222 dental patients admitted for treatment at the Virginia Commonwealth University, Medical College of Virginia School of Dentistry. According to the criteria of an elevated diastolic blood pressure (above 95 mm Hg) at three successive readings not less than five days apart, 131 patients were referred to physicians as suspected hypertensives. One hundred and thirteen patients were deemed hypertensive by their physician. A positive family history of hypertension was noted for 54% of the 113 undetected hypertensives. Of the 113 hypertensives, 6% visited their dentist yearly but did not visit their physician during the same time. On this basis we conclude that about 6% of dental patients can be expected to be referred to physicians as a result of high blood pressure screening in a dentist's office.


Chondroma of the anterior nasal spine.

Chondroma of the anterior nasal spine. Chondromas in the head and neck, and particularly in the nasal region, are uncommon. A unique case of a chondroma within the anterior nasal spine has been reported. The asymptomatic lesion was discovered radiographically and mimicked a mesiodens. The tumor consisted of benign-appearing cartilaginous tissue; enucleation has resulted in a apparent cure. A hamartomatous origin has been postulated for this unusual lesion.


Complications in treatment of a mandibular defect with a Silastic implant. Failure of a previously published Silastic implant technique in the treatment of facial asymmetry has been reported. It is a clinician's obligation to report failures as well as successes in the treatment of the oral surgical patient so that other practitioners are not misguided.


Pigmented dermoid cyst of the floor to the mouth: a comparison of two cases. Two cases of very large midline sublingual dermoid cysts are reported; one case had unique features. A useful surgical technique for the management of such cysts in described. The failure of the cyst in one case to penetrate the geniohyoid septum despite its large size and the presence of melanin pigmentation in the cystic lining are emphasized.


Multiple myeloma involving the jaws and oral soft tissues. A case of multiple myeloma with involvement of the oral cavity in a 75-year-old white man is reported. The patient had a two-year history of multiple myeloma. He had four intraoral soft tissue masses that were diagnosed as plasma cell myeloma. Each of these lesions was over a radiographically evident osteolytic lesion of the jaw. The patient was treated by irradiation and chemotherapy.


Blue nevus of the hard palate.

Blue nevus of the hard palate. The occurrence of a blue nevus of the hard palate in a 72-year-old man is reported. Of the 25 previously documented cases of blue nevus of the oral cavity, 19 were on the hard palate, three on the upper lip, and one each on the lower lip, buccal mucosa, and soft palate. Fourteen were in women and 11 were in men. All but five patients were younger than 50 years of age. The size of the asymptomatic, flat to somewhat elevated, blue-black lesion varied up to 5 mm except for one that was 10 mm in the greatest dimension. Most nevi were of unknown duration and were found incidentally during dental examination. The histogenesis of extracutaneous blue nevus is undetermined but derivation from melanogenic potential of Schwann or endoneurial cells or from stimulation of retained melanoblasts in the stroma developing into melanocytes and formation of blue nevus is possible.


Primary malignant melanoma of the hard palate. A case of malignant melanoma of the oral cavity is presented. The very high frequency of squamous cell carcinoma of the palate in Visakhapatnam, India, is compared to the rarity of malignant melanoma, even though pigmentation of the oral cavity is quite common in this geographical region.


Contouring split ribs for correction of severe mandibular atrophy. A method of contouring split ribs for use in augmentation of the atrophic mandible had been described. Symmetry, arch, and alveolar ridge form are excellent. Placement of the rib graft passively on the ridge is easier than use of a single rib with vertical saw cuts.


Clinical evaluation of free autogenous gengival grafts placed on alveolar bone. Part I. Clinical predictability. 1. Thirty free autogenous gingival grafts were placed on bone and 30 were placed on a periosteal bed. The distribution into the groups was random. All 60 grafts survived, showing that both procedures were predictable. 2. Over one-half (17 of 30) of those on periosteum demonstrated mobility by 6 months postoperatively. No mobility was observed in the group placed directly on bone. 3. Osseous placed grafts demonstrated less swelling and better hemostasis than did the periosteally placed grafts. 4. A healing lag was observed in the grafts placed on bone which lasted only for the first two postoperative visits, approximately 2 weeks. 5. No infections or sequestrations were noted in any case.


Creeping attachment after free gingival grafts. Free gingival grafts were placed in the lower anterior vestibular region of 30 patients each of whom had a gingival recession. According to the width of the recession and to the surgical procedure, the patients were divided into four groups. Group 1 showed a "narrow" (less than 3 mm) type of recession, while Group 2 had a "wide" type. In both of these groups the graft was placed over the denuded root. In Group 3 (narrow recession) and Group 4 (wide), a collar of vestibular gingiva was left in place on the lower margin of the denuded root at the moment of grafting. Measurements and photographs taken before and 1 month after surgery, 6 months and 2 years postoperatively, showed varying degrees of root covering by the phenomenon of creeping attachment. An optimal recovery of the gingival profile was obtained in the three patients of Group 1. In the other categories of patients the creeping of the attachment apparatus was relatively small (between 0 and 33%) within the 2 years of observation. The factors which seem to have a definite influence upon the phenomenon of creeping attachment are the following: width of the recession, position of the graft, bone resorption, position of the tooth and hygiene of the patient.


The effect of a urea peroxide rinse on dental plaque and gingivitis. The effectiveness of a commercially prepared oxygenating agent (Gly-Oxide Liquid) in reducing plaque accumulation and gingivitis was studied over a 3-week period. Sixty-nine dental students, ages 20 to 30, were divided into three groups: control (group I), placebo (group II), test formulation (group III). Subjects were scored using the Plaque and Gingival indices of Loe et al. at the beginning of the study and at 1, 2, and 3-week intervals. In accordance with a well-established experimental gingivitis model, oral hygiene was withdrawn for the duration of the study. No statistically significant differences in plaque development was noted. Analysis of variance showed a significant treatment effect on gingivitis (P less than 0.01). A significant difference between group I and group III was evident (P less than 0.05). The study indicates that the formulation may be effective in reducing gingivitis in human subjects. Additional investigations regarding its usefulness as a routine oral hygiene adjunct are warranted.


Accelerated reattachment with cementogenesis to dentin, demineralized in situ. II. Defect repair. Three surgical experiments, with histologic evaluation, were performed to study induced gingival reattachment to tooth root dentin demineralized in situ during flap surgery in adult mongrel dogs. Experiments demonstrated aspects of: (1) Weekly histochemical and morphological sequences of repair; (2) Repair of chronically inflamed bony defects simulating periodontal pockets; and (3) Six and 12 month repair of reattached surgical defects. Flap reattachment with cementogenesis was induced by in situ root demineralization using citric acid at pH 1.0 applied for 2 minutes. Results demonstrate: (1) The production of anchoring cementum pins extending into dentin tubules widened by demineralization; (2) Reattachment with cementogenesis of inflamed gingiva to roots exposed to chronically-infected surgical defects for 3 months; (3) Success in repairing chronic interproximal one-walled and labial one surface defects by reattachment; (4) Relative failure to repair bifurcation and horizontal bone defects by flap reattachment; and (5) Complete alveolar bone repair over most labial defects by 1 year, with maintenance of a periodontal ligament between induced bone and cementum. These findings, together with previous reports of induced reattachment to demineralized roots, provide further evidence for mechanisms and consistency and suggest that this regenerative phenomenon may be useful in repairing osseous defects in periodontal therapy.


Transgingival probing as a potential estimator of alveolar bone level. The validity of using a periodontal probe for the transgingival sounding of the alveolar crest level has been demonstrated for buccal surfaces of the jaw. The measurements from the occlusal surfaces of the teeth to the estimated level of the alveolar crest using this technique accurately reflected the actual distances measured after surgical exposure of the alveolar crest at these sites.


A comparison of the mucogingival junction in dentulous and edentulous areas. Thirty human mucogingival specimens were evaluated histologically and histochemically to determine whether a difference exists in the mucogingival junction of dentulous and edentulous areas of the maxilla and mandible. No significant differences were observed between the two areas. The presence of an intermediate zone is described, which may have clinical implications in some surgical procedures.


A technique of measurement of the depth of the vestibular fornix in the mandibular anterior region. A radiographic method of measurement of the depth of labial vestibule in the mandibular anterior region has been described. Contrast medium was applied to the lip and mucobuccal fold and radiopaque marker attached to the labial surface of each tooth. The head was positioned in a craniostat and a posterior-anterior radiograph exposed. The radiopaque boundaries of the vestibule showed on the radiograph so that they could be measured. Statistical analysis showed a recording error of 0.6 mm and an observation error of 0.29 mm, which are within the range of error acceptable for this type of recording technique.


Cowden's disease (multiple hamartoma syndrome). Report of a limited mucocutaneous form. A case of Cowden's disease has been presented and management considerations documented. Mucocutaneous lesions were the dominant feature of the disease. A rationale for differentiating Cowden's disease from other complex syndromes is considered vital to clinical practice.


Clinical reduction of gingivitis through the use of a mouthwash containing two quaternary ammonium compounds. A commercially available antimicrobial mouthrinse was evaluated among students in Mexican boarding schools. The application was made daily for 3 months under the direct supervision of the project personnel. The observations indicated that the use of this mouthrinse decreased gingivitis substantially in comparison to the use of a control rinse which consisted of flavored water. It is concluded that this mouthwash, containing the known antimicrobial agents cetylpyridinium chloride and domiphen bromide, can be of clinical benefit if conscientiously applied as an adjunct in an oral hygiene regimen of regular toothbrushing with a dentifrice.


Relationship between the width of the occlusal table and pressures under dentures during function. The effect of altering the width of the occlusal table was studied on one edentulous subject. A maxillary denture was designed to accept four interchangeable posterior occlusal segments, differing only in the buccolingual dimension of the occlusal table. The opposing mandibular denture contained pressure transducers that made contact at selected sites along the residual ridge. Pressures developed during function between the denture base and the ridge mucosa were analyzed.


Clinical evaluation of a pit and fissure sealant for young adults. A BIS-GMA sealant, Nuva-Seal, failed to provide a statistically significant treatment for subjects 17 to 23 years of age. Sealant therapy cannot be considered a cost-effective factor for this age group. Retention of the more visible tinted version of the sealant was inferior to that of the clear commercial variety. This unexpected disparity in retention of the clear and tinted sealants underscores the importance of employing the exact product of interest to the dental profession when conducting the clinical trial.


Abrasive wear, tensile strength, and hardness of dental composite resins--is there a relationship? The in vitro abrasive wear resistance, tensile strength, and hardness of seven widely used composite restorative resins have been measured. Findings indicate that the values of tensile strength and hardness are not related to the measured abrasion rates. It is apparent that abrasive wear is a complex phenomenon and that materials which have high values for strength and/or hardness do not necessarily have high resistance to abrasive wear.


Tissue reaction to dispersion alloy amalgam. Dental amalgam implanted in rat connective tissue is injurious for the first 16 days. At 32 days, the implanted amalgam is tolerated. The increased copper content of Dispersalloy did not evoke a more serious response of the connective tissue than Fine Cut or Spheraloy amalgam.


The burnishability of dental casting alloys. 1. A comparison of Table I with Table IV indicates that all the gold alloys have considerably lower burnishability numbers than are indicated by ADA specification No. 5 for the softened condition. In fact, they are even more burnishable in the hardened condition than specified for Type II alloys. 2. A comparison of Table III with Tables I and II indicates that one of the major advantages of ADA gold alloys is their ease of burnishing. 3. A comparison of Tables III and IV indicates that three of the new alloys (Paliney CB, Albacast, and Alborium) do not meet the burnishability number established from ADA specifications for Type III gold alloys in the softened condition. Moreover, three alloys (Forticast, WLW, and Auralite) probably will require softening heat treatments since their values for conditions of as-cast or hardening heat treatment are much higher than ADA specifications allow for gold alloys. All of these alloys are expected to be either impossible or difficult to burnish in the as-cast state.


Open-cast technique for metal molds used in constructing facial prostheses. A new (open-cast) technique for the fabrication of metal molds has been presented. Its simplicity relies on the use of gummed asbestos tape as a boxing agent for the investment models. This technique has the following advantages over the "lost wax" technique: (1) it requires approximately one-quarter the amount of investment material, (2) it eliminates the use of investing rings or wax patterns, (3) it eliminates the boil-out step for the wax pattern and reduces the total time required to make a metal mold, and (4) it affords a high degree of visibility. The only disadvantage is that the larger prostheses require large amounts of Lino-type metal which is very heavy. However, this has not restricted the use of this technique since these metals cast well and can be easily placed in large ovens. This technique, because of its advantages, offers more efficient use of laboratory time and personnel.


Posterior bilateral condylar displacement: its diagnosis and treatment. One type of condylar displacement (posterior bilateral) was discussed as an etiologic factor in TMJ dysfunction. Joint noise, tenderness on muscle palpation, and acute TMJ pain are all considered signs of TMJ dysfunction. Any joint noise is considered to be an early dysfunctional symptom because of its higher incidence in association with palpable muscle pain or acute TMJ dysfunction. Sometimes the joint noise will immediately precede acute muscle pain and/or fluctuate with the painful symptoms. The treatment of bilateral posterior condyle displacement has been described. The mandibular anterior teeth were shortened and the maxillary posterior occlusion adjusted so that the mandible could be respositioned in an anterior position without increasing the vertical dimension of occlusion. A silver-plated maxillary cast was obtained and mounted on a semiadjustable articulator (Hanau) with a face-bow. The mandibular cast was mounted in the dysfunctional (retruded) centric relation. The articulator was moved into a protrusive position by the amount of anterior correction that is needed to reposition the condyles into the middle of the fossae symmetrically on both sides. The original TMJ radiographs provide the necessary information for this clinical judgment. Acrylic resin was placed in the space created between the condylar sphere and stop on the articulator. An acrylic resin temporary repositioning prosthesis constructed on the metal cast has two functions. It provides a therapeutic trial for the anterior condylar respositioning, and it holds the mandible in the therapeutic position while TMJ radiographs confirm the corrective position of the condyles in the fossae. After a successful 6 to 8 week trial period with remission of symptoms, a gold prosthesis was constructed on the same cast in the same therapeutic position. It remains to be seen whether, after several years, the condylar suspension system changes from a dysfunctional centric relation to a new functional centric relation in which the patient can no longer return to the posterior displaced condylar position in the fossa. Only with painstaking observations, accurate TMJ radiographs, complete documentation, and after-care can a more scientific approach to the diagnosis and treatment of TMJ dysfunctional pain syndrome be achieved.


An evaluation of single and combined self-applied fluoride programs in schools. 1. The combined use of a twice-yearly, self-applied 2.2 percent phosphate fluoride prophylactic paste and a weekly 0.2 percent sodium fluoride mouthrinse resulted in a significantly lower caries prevalence at the same school after two years. 2. The use of a weekly 0.2 percent sodium fluoride mouthrinse alone resulted in a significantly lower caries prevalence among 11 year olds at the same school after two years. 3. The use of a twice-yearly 2.2 percent phosphate fluoride self-applied prophylactic paste did not result in a significant difference in caries prevalence at the same school after two years. 4. The combination of methods appeared to be more effective than either method used alone and the programs were more effective among nonwhites in this population with this type of analysis. 5. A study design which uses cross-sectional data to estimate incidence and to make prevalence comparisons at two different points in time can be useful when an evaluation of the effect of previously tested products is desired in school-based programs.


Classroom teachers' perceived role in dental health education. This investigation utilized mail questionnaires to determine public school teachers' perceived adequacy to teach six dental health topics and responsbility for dental health in the classroom. The majority of public school teachers surveyed in Iowa City and surrounding communities felt adequate to teach dental health topics with two major exceptions: increasing proficiency in brushing and flossing, and understanding the processes and reasons for periodontal disease. More importantly, this study indicates that many teachers do not consider dental health activities to be responsibilities of the public school teacher.


A resurvey of hypertensive patients detected in a dental office screening program. In order to ascertain the fate of hypertensive patients who were discovered through the Medical College of Virginia School of Dentistry Hypertension Screening Program, a telephone survey was conducted whereby the first 128 patients discovered to be hypertensive through the program were interviewed concerning their current state of care. All 128 patients were at least three months postreferral. Patients were asked whether or not they were still under a physician's care; those responding positively were further questioned regarding medications prescribed, medication consumption, and frequency of physician visits. In all, 109 patients were contacted. The 109 patients consisted of 18 patients treated at the hypertension clinic at Medical College of Virginia and 91 patients being treated by private physicians. Of the 18 clinic patients contacted, 17 (94 percent) were still being treated. Of the patients being treated by private physicians 62 (68.1 percent) were still being followed. Of the 109 patients contacted, 79 (72.5 percent) were still under care and 30 (27.5 percent) were no longer under care. Of the patients still under care 56 (71 percent) had been prescribed medicine and only two had discontinued medication. Forty-one patients saw their physician more frequently than every three months; 21 saw their physician every three to four months and 17 saw their physician semiannually or annually. Of the delinquent hypertensives in this study, 72 percent were still under care at the time of survey and of the previously undetected hypertensives 73 percent were still under care. It is concluded that there is still a significant drop-out-rate among hypertensives after refereral and that some void exists in the follow-up of hypertensives. The suggestion is made that the dentist may be able to assist in follow-up and possibly reduce the drop-out-rate.


The status of community advisory committees in dental education. A questionnaire survey was undertaken to determine how prevalent community advisory committees have become in the nation's dental schools and what types of committees have been formed. Responses were received from 52 (90 percent) of the 58 dental schools. The data revealed the following: 1. Nine schools (17 percent) have developed consumer committees. 2. The number of committee members varies from five to 29. 3. All the committees are composed of consumer members and school representatives, and, in all but one committee, health care providers are represented. 4. Four (44 percent) committees have advisory functions only, while the remaining five (56 percent) play an advisory and policy-making role. 5. No committee planned formal training sessions for their consumer members. 6. Of the 43 schools (83 percent) without such a committee, seven (16 percent) replied they foresee implementing a consumer committee in the future.


Continuous negative chest-wall pressure. Successful use for severe respiratory distress in an adult. Continuous negative pressure (CNP) around the chest-wall and lower parts of the body was used to treat progressively alveolar disease. Therapy with CNP produced a substantial increase in arterial oxygen tension that was sustained and permitted a decrease in oxygen requirements to 40% within 24 hours. There were concomitant decreases in intrapulmonary right-to-left shunt and respiratory frequency. During CNP therapy, no adverse effects on heart rate or blood pressure were detected.


Cytotoxic antibody complicating platelet support in acute leukemia. Response to chemotherapy. Lymphocytotoxic or thrombocytolytic antibodies were detected in 11 of 25 thrombocytopenic patients receiving repeated platelet transfusions. Platelet survival times were reduced in these patients (half-life [T/2], 32 hours) as compared to patients without antibody (T/2, 51 hours, P less than .05). In one woman with acute myeloblastic leukemia and a potent platelet antibody, combination chemotherapy resulted in a profound decrease in circulating gamma-globulin and concurrent disappearance of the cytotoxic antibody. The survival of transfused platelets in this patient was dramatically improved, and bleeding was controlled.


The smoking habits of New Zealand doctors: a review after ten years. A second survey of New Zealand doctors' smoking habits in 1972 elicited an 83 percent response from 3113 doctors. 38.5 percent had never smoked compared with 23.8 percent in a 1963 survey; 29.2 had given up smoking, and 33.3 percent still smoked. Only 21.3 percent smoked cigarettes compared with 35.3 percent in 1963. There has been a sustantial increase in non-smokers among recent graduates. Both sexes now smoke cigarettes less frequently but pipe and cigar smoking by male doctors has risen sharply. Obstetricians smoke cigarettes more often than other groups of doctors, while pathologists, medical administrators and academics smoke the least. Giving up smoking was not difficult for most former smokers except for the heavy smokers who now make up most of the persistent smoker group.


A sensitive, rapid radioimmunoassay for angiotensin II. A rapid but sensitive radioimmunoassay for the measurement of plasma angiotensin II has been developed. Antiserum to angiotensin II coupled to albumin was raised and boosted by subsequent injections of unconjugated hormone. The antibody was found to react equally with the Val5 and Ileu5 forms of angiotensin II as well as with the hexa and heptapeptide fragments. Only minor cross reactivity with angiotensin I was observed. The minimum amount of angiotensin II that could be reliably measured was 4pg per tube. Because plasma incubates resulted in large and variable losses in sensitivity, an ethanol precipitation step was employed for plasma samples prior to radioimmunoassay. The normal range of venous angiotensin II levels in ambulant volunteers was 20-83pg/ml. Highly significant correlations of plasma angiotensin II with simultaneously drawn samples for renin determination were noted. Venous angiotensin II levels in a number of clinical situations are documented.


Geographic patterns of disease.

Geographic patterns of disease. The preparation and use of a computerised grid for demonstrating the temporal and spatial distribution of outbreaks of infectious hepatitis is described. Methods of social area and cluster analysis are described and it is suggested that use could be made in New Zealand of these methods of analysis, taking social data obtained from the census and linking it with mortality and morbidity data obtained by geographical reference.


Eighteen months general practice experience with urban practice nurses. Experience working with practice nurses under the present urban practice nurse scheme is described very briefly. Financial matters are touched on briefly, as are points for and against the scheme. The personal conclusions reached with regard to patient acceptance, opportunities to practise a more preventive type of medicine and the relief of excessive pressures on the doctor, appear to make the continuance and extension of the scheme well worthwhile.


The distribution of multiple sclerosis in relation to the dairy industry and milk consumption. This report emphasises the striking correlation between the world distribution of dairy production and consumption and the incidence of multiple sclerosis. The irregular distribution of multiple sclerosis has been extensively investigated and many comparative studies of specific variables undertaken. It seems likely that there could be a combination of predisposing or precipitating factors involved in its aetiology, and that some environmental phenomenon plays a part. This report suggests that milk consumption may be a common aetiological factor.


Dialysate calcium levels, dialysis hours and the healing of osteitis fibrosa. Unselected patients receiving intermittent haemodialysis at home were examined by hand radiographs to study the progression of osteitis fibrosa. Patients were using Kiil dialysers and Drake-Willock proportioning systems. The calcium phosphorus product was controlled by an adequate dialysis schedule supplemented by aluminum hydroxide gel. Dialysate calcium ranged between 5.7 and 7.3 mg/100 ml depending on the calcium content of local tap water. In 73 percent of patients the osteitis fibrosa improved radiologically and in most patients complete healing occurred. The rate of change was slow. Patients whose bones healed had significantly higher serum and tap water calcium levels than those whose bones deteriorated. There was no significant difference in the serum phosphorus levels in the two groups. Improvement of osteitis fibrosa requires both control of calcium phosphorus product and suppression of the parathyroid gland. Long dialysis hours with a positive calcium balance during dialysis were necessary to achieve the best results.


Pretibial lacerations.

Pretibial lacerations. Pretibial lacerations are common and cause considerable morbidity, especially for elderly women. Factors predisposing to this injury are discussed and guidelines for management outlined.


Kasabach-Merritt syndrome with terminal gram negative infection. A case of giant haemangioma with disseminated intravascular coagulation (Kasabach-Merritt) syndrome) is presented. Death occurred despite therapy and postmortem evidence of clinically unrecognised gram negative bacteraemia was seen.


Contraception in general practice.

Contraception in general practice. A survey of the use of intra-uterine devices and contraception in a country practice has been made. Twenty percent found an IUD unacceptable. The contraceptive pattern of 157 women was analysed and 13.8 percent were using inefficient methods. The possibility of contraceptives being made available on the Drug Tariff is discussed.


Clomipramine in phobic and obsessional states: preliminary report. An uncontrolled trial of clomipramine for phobic and obsessional states is reported. Twenty out of 21 patients benefited.


Developing or normocellular bacterial meningitis. Occult, normocellular bacterial meningitis is described in two cases, and additional records of similar cases reviewed. It is considered necessary to perform bacteriological cultures of all cerebrospinal fluids investigated for possible infective conditions even if of normal cell count, biochemistry, and naked eye appearance.


Gynodaktarin (miconazole nitrate) for vulvovaginal candidiasis. A new potent fungicidal preparation, miconazole nitrate 2 percent (Gynodaktarin) was used in 40 patients, both pregnant, with vulvovaginal candidiasis. It was as effective in pregnant as in non-pregnant patients. Retreatment in three cases of recurrence was successful. There were no side effects reported, and the drug was found to be safe for pregnant patients and their offspring.


Antimicrobial effect of root canal débridement in teeth with immature root. A clinical and microbiologic study. The aim of present investigation was to compare the antibacterial effect of biochemical root canal cleansing in permanent non-vital upper incisors with immature with those with mature root. The material comprised three groups made up of 34, 46 and 28 teeth in which the mechanical cleansing was accompanied by flushing with sterile saline and sodium hypochlorite solutions giving 0.5 or 5.0% active chloride, respectively. Samples were taken in root canals initially after removal of necrotic tissue and after completed cleansing, transferred to solid and liquid media for aerobically and anaerobically and incubated until growth appeared or up to 10 days. The microorganisms were identified by biochemical tests and gas-chromatographic analysis. The antibacterial effect of mechanical cleansing with sterile saline was very low (9%) and limited to the teeth with mature root. The flushing with sodium hypochlorite increased the antibacterial effect to about 25%. No statistical difference was found in the antibacterial effect between flushing with 0.5 % or 5.0% sodium hypochlorite solutions. The antibacterial effect was, however, irrespective of the sodium hypochlorite concentrations, less good in teeth with immature root at the statistically significant 5% level. It was concluded that mechanical cleansing of root canals in teeth with immature root with the instruments now available is inadequate. This inadequacy cannot be compensated for by use of highly concentrated solution, with dissolving effect on necrotic tissue, for flushing. The use of such substances which also have toxic effect on the tissue should be avoided.


Fluorine gradients in outermost surface enamel after various forms of topical application of fluorides in vivo. Fluorine gradients were analysed in sound facial enamel of 58 pairs of homologous contralateral premolar teeth. A macroscopic stepwise acid etching technique was used to determine the F-concentration to the depths of 40-200 microns. Usually three successive enamel layers (10, 10, and 20 microns) from enamel surface and inwards were removed. Eight pairs of teeth (control group) which had not been subjected to any form of fluoride treatment in the study, were used to assess the difference between teeth extracted at three-week-interval. The F-gradients were almost identical, with only small differences between the teeth. F-concentrations usually decreased from about 900 ppm within the first 10 microns to about 200 ppm at a depth of 40-50 microns. In ten experimental groups (5 pairs of teeth in each group) the F-uptake was studied after various forms of topical application. Contralateral teeth served as control teeth. The highest F-uptake was observed when a fluoride varnish, Duraphat (5% NaF) was applied three times at one weeks' interval. The F-concentrations were about 2000, 900 and 550 ppm, respectively, in the first, second and third enamel layer. The increase in F-concentration in the first enamel layers analysed was significant, but not in the deepest. When testing the effect of paintings procedures with 2% NaF (pH = 7 and 5); 8% SnF2; 5% Na2PO3F; 2% APF-gel (Flura-Gel) in a similar way, a moderate F-uptake was found (100-450 ppm). The uptake of F was limited to the first 10 microns of the enamel. Only 2% NaF (pH = 5) And the APF-gel gave a significant F-uptake within the first layer. Daily mouthwashing procedures during 21 days resulted in insignificant uptake of F when 0.025% and 0.05% NaF solutions were used. Not even rinsing with 0.025% NaF solution for more than 100 days and rinsing with 0.2% NaF solution once a week for three weeks resulted in any significant uptake. The results showed that the F-uptake in vivo from conventional topical application is small and limited to the first few microns of the enamel surface. However, by prolonging the exposure of the enamel surfaces to fluorides in varnishes with high F-concentrations it appears possible to highly raise the F-concentration of the enamel surface and in deeper layers.


A method for reinforcing dental composite restorative materials. A method is presented for reinforcing dental composite restorative materials by incorporation of a polymer impregnated porous inorganic component. A method for producing such an inorganic component in the form of a three-dimensional glass fiber network is described. The structure of the network is demonstrated with the aid of scanning electron microscopy.


Clinical trials with bupivacaine in oral surgery. Bupivacaine HCL is compared to lidocaine with respect to clinical use in oral surgery. Onset, potency, and duration of anesthesia with it are documented. The major advantage of its use is the long duration of its anesthetic effect, with a very slow return to full sensation, which eases the patient through the early postoperative period.


Utilization review: P.S.R.O. and the oral surgeon. The P.S.R.O. program is being implemented to improve the quality of care through effective peer review. Effective peer review requires that the oral surgeon must not only detect problems, but analyze causes and develop, implement, and evaluate corrective programs. To actively participate in development of P.S.R.O. criteria for admission, the Department of Oral Surgery at the University of Tennessee Memorial Hospital, Knoxville, conducted a restrospective survey of oral surgery admissions. Utilization review of the oral surgery admissions was conducted to determine the average length of stay and the utilization of the operating room and the ambulatory surgery clinic for patients admitted to the hospital.


Fibrous dysplasia of the jaws in Nigerians. The clinicoradiologic features and surgical treatment of fibrous dysplasia of the jaws in forty-seven Nigerian patients are described. Marked facial deformity and functional disturbances were the main indications for operation. We noticed one case of malignant transformation. It is our opinion that a more-than-usual aggressive excision is indicated in Nigerian patients.


Local injection of corticosteroids with vestibuloplasty. Triamcinolone acetonide was injected into the mucobuccal fold adjacent to the surgical site where a vestibuloplasty with mucosal grafting had been performed. Macroscopically, the mucobuccal folds of the experimental group were both softer than those of the control animals and exhibited less tendency toward regression in the depth of the vestibule. Microscopic examination revealed qualitative rather than quantitative changes in collagen formation.


Studies on melanocytes. V. The presence of melanocytes in the human dental primordium: an explanation for pigmented lesions of the jaws. Melanocytes were observed within the dental lamina or tooth bud in three of eleven Caucasian and in all six Negro fetuses, 12 to 18 weeks of gestation, studied. The presence of these cells in the dental primordium points to a contribution by the neural crest to the formation of the tooth in mammals. The occurrence of melanocytes in the dental anlage may also explain the histogenesis of such pigmented lesions as the melanotic "progonoma," calcigying odontogenic cyst, and the pigmented odontogenic tumor of Richardson.


Histochemical demonstration of acid hydrolase activity in internal dentinal resorption. The enzymes acid phosphatase (E.C. 3.133) and beta-glucuronidase (E.C. 3.2.1.31) have been demonstrated in dentin-resorbing cells by means of histochemistry. Addition of specific enzyme inhibitros revealed that the acid phosphatase of these cells was sensitive to fluride, copper, and m?OLYBDATE BUT RESISTANT TO Tartrate. The same pattern of enzyme activity has previously been found in bone-resorbing cells.


Effects of lowered temperatures on rat pulp and gingivae. The histologic appearance of pulp and interdental papilla was observed for 2 months after cryosurgery of dental tissues in the molar region of twelve Colworth-Wistar rats. The reduction in temperature achieved was also calculated from thermocouples in the pulp chamber of freshly killed animals. Reduction to -13 degrees C. in 1 1/2 minutes was followed by destruction of the odontoblast layer and fibrosis of the pulp. Destruction of the epithelium was followed by regeneration and was characterized by a sterile inflammatory reaction. Cryotherapy is suggested to be a useful alternative to standard gingivectomy, especially in patients with blood dyscrasias, and may also be used to treat internal resorption or "pink spot."


Effects of a warm gutta-percha technique on the lateral periodontium. The microanatomy of lateral periodontal tissues was examined after root canal obturation by a warm gutta-percha technique had been accomplished. Inflammatory responses were slight and of shot duration. The use of hot instruments for the condensation of the filling material did not appear to endanger the integrity of the lateral periodontium.


Multiple cementomas (periapical cemental dysplasia). Report of a case. A case of periapical cemental dysplasia of maxillary and mandibular anterior teeth in a 48-year-old woman is presented, where the stages of calcification can be well documented.


Simultaneous production of negative and positive radiographic images. A two-film radiographic procedure which simultaneously produces "white bone" and "black bone" images is described. The white bone image (the negative image) is a conventional radiograph. The black bone image (the positive image) would be used to print radiographic images on photographic paper. This technique should be limited to the examination of inanimate objects because of the large exposure that is necessary.


Paresthesia and the traumatic bone cyst. Abbreviated case report. A case of a traumatic bone cyst is reported because of the unusual nature of the chief complaint. The initial symptom of the disease was mandibular nerve neuropathy with numbness of the left side of the lower lip and chin.


Postanesthetic palatal ulceration.

Postanesthetic palatal ulceration. An ulceration developed 5 days after the administration of a local anesthetic to the right posterior hard palate. Spontaneous healing did not occur and an incisional biopsy was performed. Uncomplicated healing followed.


Bilateral lipomas of the tongue.

Bilateral lipomas of the tongue. Multiple lipomas of the tongue are quite rare and are seldom reported in the literature. Presented herein is the case of a 76-year-old man with four symmetrical asymptomatic bilateral double lipomas of long standing on the tongue.


Cheilitis granulomatosa (Melkersson-Rosenthal syndrome). An oligosymptomatic manifestation of the Melkersson-Rosenthal syndrome is described. The importance of serial sections of the tissue specimen is emphasized. Satisfactory postoperative results are obtained.


Histocompatibility of polyvinyl acetate, an ingredient of chewing gum. The histocompatibility of polyvinyl acetate (PVA), an ingredient of chewing gum, was evaluated from both a direct irritant (toxic reaction) and an allergic (antigen-antibody) standpoint. Subcutaneous injections in rats and topical application of hamster pouches were utilized. Polyvinyl acetate was shown to cause a moderate to severe inflammatory reaction when injected subcutaneously, which peaked at day 7 and was minimal at day 42. The histologic appearance of the hamster cheek pouch was not significantly altered by the PVA. Although PVA has been used as a plasticizer in chewing gum, it was not possible to induce any histologic changes in tissues which resembled the specific changes present in atypical gingivostomatitis (plasma-cell gingivostomatitis).


Hereditary epidermolysis bullosa: oral manifestations and dental therapy. The oral and dental manifestations of epidermolysis bullosa hereditaria were evaluated in seventeen patients with this disorder. Clinical findings were correlated with the electron microscope--documented diagnosis of each variant of epidermolysis bullosa hereditaria. Significant differences in the dental and oral presentations of each variant indicate the importance of considering these findings in differential diagnosis of the variants and in treatment planning for dental disease in these patients. A rationale for surgical and restorative intervention based on experience with these seventeen patients is presented.


Compound and complex odontomas.

Compound and complex odontomas. One hundred forty-nine cases of odontoma were reviewed: sixty-five cases were accepted from the literature, and eighty-four additional cases were included from the files of the Pathology Department of the Emory University School of Dentistry. The cases were combined and analyzed together. Odontomas are most often diagnosed in the second decade of life. Sixty-five per cent of all odontomas occur in the maxilla. Compound odontomas are more common in the anterior maxilla, whereas complex odontomas occur more frequently in the posterior jaws. A slight predominance in males was seen. The most common presenting symptom was an impacted tooth with retention of deciduous teeth.


Keratonodular tonsillitis.

Keratonodular tonsillitis. Reported is an unusual lesion on the right palatine tonsil in a man with latent primary syphilis. The lesion was white, nodular, firm, and asymptomatic, and histologically had a keratinized surface; it was not caused by primary syphilis or any other known or described entity. The term keratonodular tonsillitis has been coined to designate this lesion of unknown cause or significance.


The epithelized oral sinus tract.

The epithelized oral sinus tract. Sinus tracts that extended from periapical lesions to the alveolar mucosa were surgically removed and examined microscopically. The results indicate that sinus tracts may be lined with stratified squamous epithelium. More commonly, however, these tracts are lined with granulation tissue.


Morphologic and enzyme histochemical observations on the pulp of human primary molars 3 to 5 years after formocresol treatment. The state of the pulp of twenty-seven primary teeth treated by formocresol pulpotomy (clinically and radiographically successful) was assessed 3 to 5 years after treatment. A wide variation was found in the pulpal condition, from normal pulp tissue to total necrosis. Resorption and apposition of hard tissue were common findings. Five teeth were freeze-sectioned and incubated for histochemical demonstration of oxidative enzymes. The pulps of two teeth were vital; two teeth had necrotic areas subjacent to the amputation paste; and one pulp was totally necrotic. Six teeth were extracted 5 minutes after formocresol pulpotomy and incubated for demonstration of oxidative enzymes. An unstained zone, 1 to 2 mm. deep, was seen in all incubated sections. In conclusion, it seems that the formocresol method should be regarded only as a means to keep primary teeth with pulp exposures functioning for a relativley short period of time.


Localization of impacted canines with Status-X radiography. There are, at present, a number of clinical and radiologic methods available to establish the buccopalatal relationship of an impacted maxillary canine. A new method, employing the Status-X x-ray machine, can now be used. This technique makes use of the fact that the anode of the Status-X machine is considered to have an almost point source of x-radiation. Applying the laws of central projection, an object closer to the focal point will produce a larger image on a film than that produced by an object of equal size but farther away from the focal point. In a recent series of twenty-eight canine transplant procedures, this method was used with great success to establish, preoperatively, the position of the impacted canines.


Comparison of panoramic radiography and Water's projection in the diagnosis of maxillary sinus disease. Pantomograms and Water's views were independently reviewed by two radiologists with regard to detection of maxillary sinus abnormalities. Panoramic radiography was found to be a better radiologic approach than the Water's projection for the detection of cystlike densities in the maxillary sinus. Cloudiness of the maxillary sinus and sclerotic change of adjacent bony structures were better demonstrated on the Water's view. These two techniques supplement each other and both should be used in order to obtain a more accurate diagnosis of maxillary sinus disease.


T cell leukaemia in the rat: stable marker chromosome in leukaemic cells. The karyotype of a transplantable T cell leukaemia which arose originally in a PVG strain rat undergoing chronic internal beta irradiation of the spleen was examined and a marker chromosome was found. Although the leukaemia progressively became more acute during 4 years of continuous passage the marker did not change. Cytogenetic analysis of normal rats given an acute exposure to external irradiation revealed, among other abnormalities, a marked of the same morphology indicating that the original marker was probably radiation induced. This is the first description of a stable marker chromosome in an experimental animal leukaemia.


Osteosarcoma associated with acromegaly: a case report. A case of acromegaly who developed an osteosarcoma is recorded, with persistently raised levels of growth hormone. It is possible that there was some aetiological relationship between the increased rate of bone formation and the development of the osteosarcoma.


Barium enema findings in type I hepatorenal glycogen storage disease. Four children with Type I hepatorenal glycogen storage have been studied by barium enema. All showed strikingly similar changes of a smooth-walled, slightly narrow but normal length colon without any haustration. The findings simulated colitis but the patients had either mild diarrhea or no gastrointestinal complaints. Small bowel series was normal. Endoscopy and biopsy failed to provide an adequate explanation, there being no evidence of glycogen storage in the biopsy material and the degree of colitis in two patients who were endoscoped was minimal. The explanation for these radiographic findings is not known at present, although they have similarities to the "cathartic colon syndrome" described in adults.


[Use of dental hygienists in caries prevention]. Two caries preventive programs were carried out in the Bergen School Dental Service in order to test various modes of topical application of fluorides and the efficacy of using dental hygienists in the delivery of preventive dental care to school children. In the first program, starting in 1951, A 2% netutral sodium fluoride solution was applied topically four times during one month to one quadrant of the maxillary teeth, the other quadrant serving as control. This series of application was repeated one year later, while the caries registration was followed up until 1956. The results are given in Table 1, comprising 128 children who were 11-12 years old at the start of the study and were still present at the same schools in 1956. A reduction in caries incidence of about 25 per cent was obtained during the five years period. In the second program, beginning in 1963, acid stannous hexafluoride as well as neutral sodium fluoride solutions were used separately in groups of children (7-11 years of age). The total number of children was about 2000. Two groups received four topical applications annually within one month, while in two oher groups the applications were given twice a year. This topical application program was continued for four years. For several reasons pure control groups of children of corresponding age could not be established. Instead the treated groups were compared with children who under supervision brushed their teeth (already from 1964) with 0.5% neutral sodium fluoride solutions five times per year during the school hours. All children received appropriate information and motivation for improved oral hygiene and food habits by the dental hygienists individually in the treated groups and in groups in the comparison group. The results are given in Table 2. The caries reduction obtained per year reached maximally about 40 per cent. This investigation shows that dental hygienists are able to carry out valuable caries preventive work at dental clinics, and it is justified to assign this type of health personnel to separate caries preventive tasks which require little supervision time from the responsible dentists.


[Occurence of dens invaginatus among a group Norwegian children]. The aim of the present investigation was: 1) to determine radiographically the prevalence of maxillary incisors with invaginations, and of individuals with such teeth in a Norweigian population. 2) to classify the invaginations according to Hallett (1953), 3) to test the findings for sex differences, 4) to determine the concordance between a radiographical and a clinical method for identifying invaginations. Based upon a material of 415 school-children it was found radiographically that approximately 1/8 of the maxillary central incisors and nearly one half of the lateral incisors had invaginations. More than half of the children had one or more invaginated teeth (Table 2). The majority of the invaginations were of class I/III. Only a few were classified as class III (Table 2). The findings are comparable to those of Hallett (1953). Boys had a higher incidence than girls of class III invaginations in lateral incisors. The difference was statistically  significant (5%). The girls had more class I/II invaginations in the central incisors than the boys, but the difference was not statistically significant. In the clinical examination three of four lateral incisors, one of four central incisors and four of five individuals were found to have invaginations. All invaginations found in the radiographic investigation were also registered in the clinical examination.


[Toxoplasmosis and chronic myeloid leukemia]. A patient suffering from chronic myeloid leukemia and used as a donor of leucocytes was found to have toxoplasmosis associated with a high level of IgG without an elevation of IgM which was maintained for several months. This case raises several points for discussion. Toxoplasmosis is a frequent complication of malignant hematological disease, it is often severe with neurological complications in more than half the patients affected. It is often difficult to diagnose. The parasite is arduous to isolate and serology is problematic to interpretate without reference to previous samples. This suggests it would be wise to measure the titre of anti-toxoplasma antibodies as part of the initial investigations of every malignant hemopathy and to repeat the measurements during the evolution of the disease. Any patient showing a high serological titre, even though it is stable and without IgM should be given systematically a specific treatment for toxoplasmosis, for as in the patient presented in this paper, such a serological picture is compatible with an increasing infection. The frequence of high serological titres seems to be greater among patients suffering from chronic myeloid leukemia than among another people. Then, transfusion of leucocytes of such patients may be the source of parasite transmission; this paper relates one case of post-transfusional toxoplasmosis.


The erythrocytic line in refractory anemia (preleukemia or hemopoietic dysplasia) and myelomonocytic leukemia. II. Some unusual morphologic variants of the polychromatic normoblasts and reticulocytes. In a combined scanning and transmission electron microscopic study of the red blood cell line in patients with refractory anemia (preleukemia) and myelomonocytic leukemia, certain elements with abundant, convoluted membranes that formed projections over the cell surface were observed. These cells were both normoblasts (nucleated) and reticulocytes (anucleated) and constituted what appeared to be a distinct subpopulation of the red blood cell line. It is possible that in these erythrocytes there is a nucleocytoplasmic asynchronism. We are not certain, however, that they are linked to the leukemic process.


[A simple method for the removal of anaesthetic gases with the  Engström respirator]. With the Engström Respirator the waste gases can be removed by using the rebreathing position and by replacing the reservoir-bag with a long widebore tubing.


A possible conformation for double-stranded polynucleotides. A model is presented for double-stranded polynucleotides which involves side-by-side meshing of the two strands rather than double helical intertwining. The sugar-phosphate backbone has a twisted strip-like character, yet base-pairing of the Watson-Crick type is still possible. Structural features of the basic model are described and coordinates are presented for a representative example. The structure has, on the whole, reasonable sterochemical contacts, and can be shown to produce a fiber diffraction pattern with x-rays not unlike that of the B form of DNA.


Ultraviolet photoelectron studies of biological purines: the valence electronic structure of adenine. The UV photoelectron spectra of adenine, 9-methyladenine, and 6-methylaminopurine contain highly resolved bands arising from the six highest occupied molecular orbitals. The spectra have been analyzed using UV absorption data, photoelectron data from previous studies of heterocyclic compounds, and results from both semi-empirical and ab initio molecular orbital calculations. The analysis indicates that the first, third, and fifth photoelectron bands in adenine and the two methyl substituted derivatives arise from pi orbitals. The second, fourth, and sixth bands arise from nitrogen atom lone-pair orbitals. Compared to adenine, the six uppermost orbitals of 9-methyladenine and 6-methylaminopurine have lower ionization potentials. This destabilization of the valence electrons is expected to play an important role in causing the increase in base stacking forces observed in methyl substituted adenines.