New aspects of preleukemic disorders.

Preleukemic disorders are a controversial group of panmyelopathic disturbances that often precede the emergence of acute myeloblastic or myelomonocytic leukemia. In most instances, these preleukemic disorders are characterized by slowly developing myeloblastosis of the bone marrow. They include preleukemia, primary acquired panmyelopathy with myeloblastosis or smouldering acute leukemia, erythroleukemia, and subacute myelomonocytic leukemia. Sometimes, transitions between these various preleukemic disorders may be observed in a single individual. Abnormalities in cellular differentiation are expressed in cytochemical aberrations and in elaboration of colony forming units by marrow cells of patients with preleukemic disorders. Cytogenic and cellular kinetic abnormalities link preleukemic disorders closely to acute myeloblastic or myelomonocytic leukemia, although in many patients with preleukemic disorders, conversion to acute leukemia is not observed or perhaps not recognized. Understanding pathogenetic and pathophysiological aspects of preleukemic disorders may shed light on aspects of cellular proliferation and cellular differentiation in the acute leukemias.


[The vertical relation].

A phonetic and relaxation method combined with teleoradiography was used to measure the interocclusal interval in five subjects. The action potential of the left and right masseter muscles were derived while the subject was drinking liquid. After fitting each subject with a Shore bite path plate which reduced the interocclusal interval to 0 mm, the same experimental procedure was carried out. No significant differenced could be established using a unidirectional lead with pseudointegration. In spite of the extremely small sample, the results tend to indicate that resting suspension changes corresponding to the vertical dimension.


[Stability of temporomandibular joint relations in the edentulous].

Loss of teeth causes a change in the relationship of the mandibular condyles to the articular fossa of the temporal bone. The movement of the joint is pathologically restricted by the relation of the articular disc. The study showed that the function of the masseter muscles could be normalized with a modified Shore bite path plate. This normalized function was expressed by a change in jaw relation. The theoretical foundation was discussed and the results of preliminary investigations were presented.


[Longitudinal study on the abrasion of plastic teeth in total prostheses].

After a period of two years, the abrasion rate for standard plastic lateral teeth is one-tenth of a millimeter. The abrasion rate is then one-tenth of a millimeter per year for each succeeding year. A vertical loss of approximately four-tenths of a millimeter, for example, occurs during a five-year period. The abrasion rate is not related to the position of the prosthesis. The molar region shows a lesser degree of abrasion than anterior sections of the dental arch.


[Periodontal conditions in patients over 70 years old wearing removable partial dentures].

The periodontal state of 70-year-old patients was compared with that of patients 10 years younger. It was established that the, in part, significant differences in favor of the older patients were not attributable to the distribution of the remaining teeth, the type or support of the prosthetic device, oral hygeine, or general physical condition. On the basis of this study, it was concluded that only those patients in the group over 70 years of age were fitted with partial dentures whose teeth showed a lesser amount of previous periodontal damage and/or were periodontally more resistant. This contributed to a satisfactory prosthetic care.


[Review of implantation materials].

The use of nonmetalic, ceramic materials has led to encouraging developments. Some metal implants have proved to be more reliable in general practice in respect to the mechanics and statics; part of the developmental goal however should include compound materials. Metal implants, tolerated by the organism under favorable conditions, were not accepted as well as the ceramic material. Recently, the long-term prognosis therefore has been viewed with reservation. Even though the tensile values were favorable, the mechanical properties were good, and the corrosion rate in terms of adequate tissue tolerance was generally satisfactorily low for metal, the organism still responded to metal as a foreign body.


Clinical aspects of continuous neonatal oxygen monitoring.

Twenty newborn infants (gestational age 30--40 weeks, weight 980--3400 g) were studied in two groups to compare two commercially available systems for continuous in vivo oxygen monitoring: the So2 catheter and the transcutaneous Po2 (TcPo2) electrode, and their respective electronic systems. Measurements from these systems were correlated with determinations made from samples intermittently drawn and measured by conventional So2 and Pao2 in vitro methods , respectively. Information about these two in vivo oxygen monitoring systems was then related to our previous experience with the bare-wire earlobe O2a electrode. Measurements from the two in vivo monitoring techniques studied showed good correlations with their respective in vitro oxygen measurements: So2 catheter, y = x - 3.08, r = 0.98 (range studied 74% to 100%) and transcutaneous electrode, y = 0.98x + 0.57, r = 0.89 (range studied 34 to 92 mm Hg). It was concluded that all three systems give a good reflection of central arterial oxygen (either Sao2 or Pao2)). The system to be used in specific clinical situations should depend on condition of the baby and stage of treatment, need for an umbilical line to measure other variables, equipment available, and training of personnel.


[Effectiveness of hypoxic hypoxia as a means of protecting the body from ionizing radiation exposure with the use of sodium oxybutyrate and mexamine].

While exerting a pronounced antihypoxic action on the body of white mice under nypoxic hypoxia, a combination of sodium hydroxybutyrate and mexamine given in comparatively low doses (100 and 2.5 mg/kg, respectively) did not remove the radioprotective effect of hypoxic hypoxia. In hemic and histotoxic hypoxia the drugs did not exhibit any antihy-oxic action.


Structure and types of dental manpower.

The different categories of dental health personnel, professional, operating and non-operating auxiliary are defined and their roles examined. Where professional and auxiliary dental manpower is in short supply the use of non-dental personnel such as teachers and health educators should be emphasised as a means of providing firrst aid and preventive measures. Manpower remains the central problem in improving oral health. Although the number of dental schools and the total number of dentists has increased in the past two decades, the dentist/population ratio has declined. Considerable variations occur between countries and the geographical distribution within countries is very uneven, an undue proportion often practising within the large cities. A greater increase in numbers of dentists, though desirable, will not be sufficient to solve the problem of adequate dental health coverage in this century. The advanced skills of the dental graduate are not required for many routine procedures and greater use must be made of operating auxiliaries. More research is needed into the best composition of the dental team. Increased use of larger, more complex teams seems likely to be the most important development for the future. This will require a careful reappraisal of the curricula for all categories of personnel. WHO is actively engaged in formulating guidelines for dental administrators in the development of educational and planning criteria for the improvment of dental health.


Oral health programme of the Western Pacific Region of the World Health Organization.

The development of the WHO Western Pacific Regional Oral Health Programme was briefly traced through two of the three multi-phased periods (from 1971--77) of WHO collaboration. The third period of development (1978--83) is by a planning exercise referred to as 'the regional oral health medium-term programme'. This exercise takes into account the problem areas at the end of the second period. Twelve quantifiable targets for achievement by 1983 are identified. Specific and general activities, approaches and strategies for achieving targets are briefly outlined. It is expected that the programmes for prevention of dental diseases will be intensified in the region during the current five-year period. There is also a growing tendency for consultants from developing countries and areas to be utilized in the region under the concept of Technical Cooperation among Developing Countries (TCDC). Systems will also be developed to monitor the progress in achieving targets in the region and changes instituted where necessary.


Preventive responses to various national problems.

The prevalence of dental disease appears to be increasing, especially in developing countries. The adoption of traditional Western-style oral health care delivery systems, which may be entirely inappropriate to the local circumstances, has resulted in the establishment of expensive and inefficient services in many parts of the world. In planning a realistic oral health service, administrators must first identify the problem, estimate available manpower in terms of number, type and distribution and identify the economic resources which can reasonably be allocated to oral health. Five categories of oral health status have been identified in various countries ranging from a situation characterized by very low, stable or increasing oral health problems with an acute shortage of manpower and almost non-existent dental care delivery system to the situation found in the most advanced countries where the oral health problem, though very high, may be already decreasing and where there is adequate manpower and delivery systems are highly developed. A preventive strategy for each of these five categories is presented which it is hoped would lead to an improvement of the oral status of the world's population as fast and as cheaply as possible.


Periodontal therapy for the ageing mouth.

Epidemiological studies have shown that the prevalence and severity of periodontal disease and tooth loss increase with age. Other studies indicate that gingival recession becomes more prevalent as age progresses. In addition, it has been demonstrated experimentally that elderly individuals develop more rapid and severe gingivitis than young individuals following the abstention of oral hygiene. However, to date no one has established which changes associated with ageing are responsible for these clinical observations. A population of elderly patients (60 years or older) has been evaluated at Northwestern University as to the role of gingival recession and inadequate zones of attached gingiva in the development of dental plaque and gingivitis. The controls for this study consisted of a young population (under 25 years old) with similar gingival defects. In addition, we have found that elderly individuals need more frequent oral prophylaxis for the maintenance of gingival health and to prevent further loss of alveolar bone. This need for more frequent oral prophylaxis is due in large part to the increased incidence of exposed root surface which allows for more rapid plaque accumulation and calculus formation than do enamel surfaces. This and other preliminary evidence suggests that elderly patients with periodontal disease should receive more aggressive therapy than is commonly practised today.


Dental hygienists in Japan.

Suzuki and Sato (1978) reported data obtained from 410 dental hygienists aged 24--39 years of age. The most frequent reasons for leaving their jobs were difficulties in personal relations and then disappointment with the commercialism of dentists. Additional reasons included no fixed programme of the routine aspects of their work, compulsory duties beyond those legally permitted them and no leadership in the clinic. In contrast, many dental hygienists felt rewarded by the success achieved through health instruction of patients, appreciation of their work by patients and having the opportunity to demonstrate their professional abilities. Given these kinds of perceptions about the occupation of dental hygienists, expressed by hygienists themselves, it would appear imperative that the dental profession and health administrators in Japan consider the disincentives inherent in the jobs and attempt to convert these to incentives.


Some thoughts on epidemiologic indexes for assessing the need for treatment of periodontal diseases.

Various indexes have been developed and used to collect information on the prevalence, aetiology and prevention of periodontal disease, but few efforts have been made to utilize this information to assess treatment needs in the populations examined. Recently, Johansen et al. (1973) have developed the Periodontal Treatment Needs System and Møller and Beck (1976) included an assessment of treatment requirements in the Collaborative Study of Dental Manpower Systems sponsored by WHO and the USPHS. The value of these various indexes and the problems encountered in their application to field studies are discussed in detail. The lessons learned have been incorporated into the second edition of the booklet Oral Health Surveys (WHO, 1977), but it is contended that the methods advocated are still less than perfect. Particular doubt is cast on the recommendation for the use of a periodontal probe in field surveys often conducted in primitive conditions and by examiners with minimal training and experience. It is suggested that the critical depth of 3 mm is too small to be regarded as requiring radical treatment. The need for a treatment index is questioned in the light of the probability that treatment needs could not be fully met even in developed countries.


Cytotoxicity against the K562 erythroleukemia cell line by human natural killer (NK) cells which do not bear free Fc receptors for IgG.

When Fc receptors (FcR) on normal human peripheral blood lymphocytes were induced to modulate by overnight (18 h) incubation in the presence of soluble or particulate immune complexes, the natural killer (NK) activity of the effector lymphocyte suspension, as measured against the K562 erythroleukemia cell line, was significantly, but only partially, inhibited. The NK activity which remained was always strong, and was not significantly inhibited by inclusion of antigen-antibody complexes in the cytotoxicity assay, nor was it further depleted by adsorbing the modulated cells on plastic surfaces coated with immobilized antigen-antibody complexes. Antibody-dependent cell-mediated cytotoxicity (ADCC) against rabbit antibody-sensitized Chang liver cells was totally abrogated following the modulation process, and could not be restored by exposure of modulated effector cells to trypsin, indicating that the FcR had actually been shed and were not merely being blocked with immune complexes. Although freshly isolated peripheral blood lymphocytes active in natural (or "spontaneous") cytotoxicity have been shown to bear FcR, our data indicate that NK activity against the K562 cell line can be effectively mediated by NK cells which have lost their FcR. This supports the concept that NK activity against K562 is independent of FcR, and, therefore, of IgG.


Etiology, pathogenesis and classifications of knee fractures.

Fractures of the knee include fractures of the lower end of the femur, upper end of tibia, and patella. The term articular fractures has been avoided in this text because it would exclude supracondylar fractures of the femur, fractures of the tibial spines, and epiphyseal separations in which the articular surfaces remain uninjured. By agreement with the other rapporteurs to this Congress, we excluded from our review separation of the apophysis of the tibial tubercle, fractures of the tibial spines, and osteochondral lesions.


A gene that modifies the sex ratio in a bisexual strain of Sciara ocellaris.

The influence of an X-linked recessive mutation, sepia, on the sex determination of a bisexual strain of Sciara ocellaris was studied. It induces an alteration in the sex ratio, especially in the progeny of heterozygous females, increasing the proportion of males. These results cannot be explained by differential fecundity of the female parents of different genotypes nor by differential mortality between the sexes. The occurrence of gynandromorphs indicates that the mutant probably interferes with the processes of X-chromosome elimination. Observations that heterozygous females which received the sepia allele from their mothers produced a higher frequency of gynandromorphs than females which received the mutated allele from their male parents, suggest that the mutation is interfering with the mechanism of chromosome elimination present in the egg cytoplasm.


Sensitivy of mouse molar tooth germs to x-ray irradiation in vitro.

Molar tooth germs, extirpated from 18-day mouse fetuses were cultured on Millipore filter strips in Falcon organ culture dishes. The tooth germs were exposed to 250 kVcp X-rays at 106 R/min. for a total exposure of 1 600 R. Tissues were harvested on a daily basis for a total period of 12 days and were examined microscopically, utilizing H and E stain. Severe disorganization of the tooth germs was evident within 24 hours of irradiation. The basement membrane became hyalinized; pyknotic nuclei and lysed cells were observed throughout the dental papilla, but mostly in the regions of the presumptive cusps. Although a thin layer of predentin was elaborated by the odontoblasts, the matrix failed to calcify and enamel matrix was not produced. Cultures older than 10 days demonstrated extensive cell death. The entire pulp was reduced to a mass of necrotic cells and the ameloblastic layer consisted of an epithelial remnant covering the cuspal tips.


3H-glucosamine electron microscope autoradiography after isolated labeling of the enamel organ or the dental papilla followed by reassociated toothgerm culture.

Electron microscope autoradiography was performed after isolated labeling with 3H-glucosamine of the enamel organ or the dental papilla of Swiss mice followed by reassociated toothgerm culture for 9.30 h and 19 h. After these two time intervals in case of an enamel organ labeling, numerous silver grains were observed in the intercellular spaces of the stellate reticulum indicating a concentrating and storing role of the latter. After dental papilla labeling, an almost complete absence of radioactivity was noted at 19 h. suggesting that 3H-glucosamine is not stored by the dental papilla. A clear labeling of the basement membrane area and of the adjacent aperiodic filamentous material found on the pulpal side was only observed after enamel organ labeling with 3H-glucosamine, suggesting an epithelial origin of the glycosaminoglycans found in these structures.


The growth of the autotransplanted rat incisor tooth odontogenic organ.

74 rat incisor odontogenic organs were autotransplanted intradermally into the auricle. The animals were killed in groups of four up to eight months after grafting. Out of 61 grafts examined from the third week onward, 46% exhibited a typical odontogenic organ or a well differentiated tooth with pulp, vessels and nerve fibers. In 33% only scattered epithelial islands were formed. 21% of the grafts ended as osteodentin. Following the initial trauma leading to aseptic necrosis, the most primitive odontogenic organ cells survive to generate a new tooth. The grafted odontogenic organ resumes its existence as a complex structure which mobilizes its own vascular and nervous supply from the host dermis as evident from nerve fibers which penetrated the tooth pulp. Since all original nerve fibers of the graft had to be disconnected from their cell bodies, they obviously degenerated. Thus any nerve fiber observed in the regenerating tooth pulp had to be of dermal origin.


Electrophysiological properties of human dental pulp cells.

Resting membrane potentials and electrotonic potentials of human dental pulp cells (peripheral and inner cells) were recorded from intracellular measurements. The results show a high resting membrane potential (- 80 mV) for peripheral cells and a low resting membrane potential (- 30 mV) for inner cells. The peripheral cells present rectification properties (outward going rectification and delayed rectification) and a negative post potential at the end of the depolarizing current. These properties are similar to those found in some receptor cells. On the basis of their morphological characteristics, these peripheral cells are compared to odontoblasts in their early stage of development.


Local analysis or the composition of amphibian and shark teeth using laser probe mass spectrometry.

In the intention of confirming and extending previous studies on the ultrastructure of the teeth of the lower vertebrates, we have performed analyses of the amounts of various chemical elements present in the teeth of two amphibians and a shark. For this purpose we employed a laser probe mass spectrometer, with which we were able to measure profiles of the variation of amount of the different elements with depth at the different points chosen for analysis. The results are expressed as relative abundances using phosphorus as reference. Differences in the relative amounts of many elements can be observed at different sample points on a tooth, and, for a given sample point, at different depths. These differences certainly reflect ultrastructural features, although some of these may not yet have been described. Fluorine has been found to be much abundant in the teeth of a shark than in those of amphibians.


[Influence of inflammation on keratinocytes of the palatal mucosa of guinea pigs].

The palatal mucosa of the guinea pig contained in the normal state a certain number of binucleated cells. Injections of substances inducing inflammation (carrageenan, calcium pyrophosphate dihydrate, monosodium urate) were made in order to produce an inflammatory reaction in the palatal mucosa of young male and adult guinea pigs. The percentage of binucleated epithelial cells was estimated at different time intervals after injections. For the three injected substances, a significant increase of the binucleated epithelial cells was noted in the palatal injected mucosa, when compared with a healthy mucosa or a mucosa having been injected with saline.


[Influence of culture media on the growth of Streptococcus mutans ATCC 25175 in the presence of various carbohydrates and their derivatives].

The growth of Streptococcus mutans ATCC 25 175 has been studied in the presence of various sugars (sorbitol, mannitol, lycasin, sorbose and xylitol) and compared to sucrose, glucose and fructose, added to a complex and a synthetic culture medium. In these two media, the decrease in pH was related to the bacterial growth; this fact was confirmed by the dosages of the liberated lactic acid. In the complex medium, the different sugars influenced only slightly the bacterial growth, whereas in the synthetic medium the micro-organisms did not grow in the presence of sorbose, xylitol or lycasin 80/55. An adaptation period was necessary before the beginning of bacterial growth in the synthetic medium supplemented with sorbitol and mannitol.


Oligodontia: a study of its prevalence and variation in 4032 children.

The frequency of oligodontia in the study group was 4.34 percent; 79.82 percent of those with congenitally missing teeth lacked not more than two teeth. In terms of number of teeth missing, there was no significant difference between the maxilla and mandible. When considering the whole dentition, bilateral agenesis was more common than unilateral agenesis. The findings of this study largely confirm the results of previous studies of oligodontia.


The effect of stannous fluoride on plaque scores.

A homogeneous group of 37 patients was chosen. The first six days involved brushing and rinsing with stannous fluoride compounds for the experimental group and placebo compounds for the control group. The next five days involved rinsing only. There was a significant difference in plaque scores during the period of rinsing only.


A study of oligodontia in a sample of New Orleans children.

From this investigation, the following conclusions can be drawn. The prevalence of oligodontia in 847 New Orleans children was 7.44 +/- .9 percent with a total of 119 teeth absent in sixty-three subjects, excluding third molars. No statistically significant difference in prevalence occurred between the sexes. Difference in bilateral and unilateral tooth absence was not statistically significant. The teeth most frequently absent in decreasing order were the mandibular second premolar, maxillary lateral incisor, and maxillary second premolar. No statistically significant differences occurred in the frequency of absence of the mandibular second premolar and the maxillary lateral incisor. No statistically significant differences occurred in tooth absence for the following comparisons: Maxilla vs mandible . Bilateral vs unilateral . Right vs left.


Ready-to-eat cereals and dental caries in children: a three-year study.

In a three-year study of 145 adolescent males in a boarding school in Wisconsin, there were no statistically significant differences in dental caries experience between a group consuming phosphates added to pre-sweetened and non-presweetened ready-to-eat cereals, and the control group, or between cereal eaters and non-cereal eaters.


The specificity of response to experimental stress in patients with myofascial pain dysfunction syndrome.

Comparison of autonomic and muscular response to experimentally induced stress in normal individuals and patients with myofascial pain dysfunction (MPD) syndrome revealed greater masseter and frontalis activity in the patient group, higher gastrocnemius activity in control subjects, and no significant difference in skin conductance and heart rate. This specificity of response to stress supports the psychophysiologic theory of MPD syndrome.


Electromyographic correlates of experimentally induced stress in diurnal bruxists and normals.

Diurnal bruxists and normals were compared in responsiveness to stress and on psychological status. Results indicated that masseter EMG activity was significantly higher at rest for bruxists than normals, that bruxists responded differentially more to stress than normals, and that no significant differences were present between bruxists and normals on the psychological measures.


New initiator systems for dental resins based on ascorbic acid.

Several promising initiator systems for the ambient polymerization of dental monomers were developed utilizing the oxidation-reduction reactions of certain organic peroxides and certain transition metal compounds with L(+) ascorbic acid and its derivatives.


Effects of nitrous oxide during organogenesis in the rat.

Susceptibility of the pregnant female rat to possible teratogenic effects from acute nitrous oxide exposure was studied. A statistically significant increase in fetal death rate (ranging from 19.1 to 7%) was observed with exposure during various periods of organogensis. No significant differences in fetal length, weight, or organ-to-body-weight ratio for spleen and liver were observed.


Sources of stress and interpersonal support among first-year dental students.

Sixty-three first-year dental students were surveyed to gather information regarding sources of stress within the dental school environment and sources of interpersonal support. The results indicated that, as a group, dental students feel most stressed in regard to demands on their time, mastery of the volume of material presented, and inconsistent feedback from faculty. Significant sex differences emerged, with women reporting more stress associated with peer competition, fear of failure, fear of falling behind, and lack of positive feedback. Analysis of interpersonal support data revealed that women reported fewer peers as part of their support networks, especially in regard to task-oriented interactions. Possible strategies for reducing environmental stress and the development of support services for female students are considered in light of the findings.


Grade averages and DAT scores as predictors of performance in dental school.

Admission into dental faculties is based on preprofessional average, prerequisite average, and DAT scores among other criteria. This study investigated the predictive validity of these variables on success in the Faculty of Dentistry at the University of British Columbia. Data on 312 students admitted between 1969 and 1976 were subjected to multiple regression analyses. Results showed that overall preprofessional average significantly correlated .17 to .29 with nine first- and second-year course grades, .36 with first-year average, and .29 with second-year average. DAT manual average correlated significantly with five course grades from .20 to .36, .20 with second-year average, and .30 with third-year average grades. Chalk carving correlated significantly .20 to .40 with five course grades and .24 with third-year average. It is recommended that overall average and chalk carving be given equal emphasis in the selection process.


Period end clinical evaluation.

This paper describes the evolution and operation of a system of clinical evaluation which has been in use in the Faculty of Dentistry at McGill University since 19749 Students are evaluated for their overall performance throughout an entire clinical period rather than for individual treatment steps or units.


Evaluation of predictor variables for a self-instructional preclinical course.

Several studies have shown that the Dental Admission Test and predental grade point average have validity in predicting performance in dental school. The purpose of this two-year study is to compare these predictors with a manual skill exercise to determine their usefulness in predicting manual dexterity success in operative dentistry. Sophomore students were instructed to make preparations on an Ivorine block following imprinted outlines. Correlation to performance on laboratory examinations was computed. Results indicate the traditional predictors have limited usefulness in manual skill prediction while the Ivorine block exercise demonstrated consistent correlation over both years. The emphasis on manual dexterity in preclinical dental courses requires that appropriate variables be used in selecting students.


The improvement of technical skills in preclinical courses.

One hundred fifty-four freshmen dental students were administered a fine motor ability test prior to and at the completion of a series of preclinical technique courses. The pre- and posttest performances were compared for each student to determine whether an improvement of technical skill had occurred. The pre- and posttests were also graded using the rank ordered method. The number of students who demonstrated improvement in technical skill was compared to the number of students who improved in grades to establish whether the change in grades was indicative of the observed change in technical skill. Most students improved in technical skill; however, grades did not reflect this improvement.


Assessment of the impact of medical device legislation on the dental trade industry.

FDA authority over medical devices is a fact of life, certain to have an effect on the dental trade industry. Trends toward acquisitions and mergers of companies within the dental trade industry and the employment of additional personnel, in response to the regulations, have already become apparent. While some improvement in the quality of dental products can be anticipated, it is also expected that the regulations will result in fewer sources of dental products, higher costs for products fewer new products, and a reluctance to accept goods for return or repair. Whether the net impact of the Medical Device Amendments upon the industry will be positive or negative, remains to be seen.


Imaging properties of intraoral dental xeroradiography.

A prototype imaging system for intraoral dental xeroradiography has been described. In vivo evaluations of image quality show that intraoral xeroradiographs are superior to conventional intraoral film radiographs primarily because of the wide latitude and edge enhancement properties of xeroradiography. In addition, intraoral xeroradiography requires only a third of the radiation dose of corresponding intraoral film techniques.


Treatment and posttreatment effects of chewable fluoride tablets on dental caries: findings after 7 1/2 years.

The data from the Wayne County study indicate that administration of fluoride tablets in school should be recommended in nonfluoridated areas as an effective public health measure for the prevention of dental caries. The finding that benefits persist for at least 1 1/2 years after treatment is discontinued further accentuates the public health appeal of the procedure. As the data show no clear-cut superiority in posttreatment benefits for two fluoride tablets a day, a single tablet daily can be recommended as more suitable for school programs because of lower cost and greater feasibility.


Perception of pain to three different intraoral penetrations of needles.

There are no significant differences in perception of pain produced by penetrations of 25-, 27-, and 30-gauge needles in the retromolar fossa. Six dentists received three series of six needle penetrations, three in each retromolar fossa, at one-week intervals. The penetrations were made to a depth of 2 to 3 mm with use of a rapid in-and-out motion by 25-, 27-, and 30-gauge needles in an alternating sequence. The perception of pain for each penetration was recorded, tabulated, and statistically analyzed. There were no significant differences in the perception of pain elicited from the use of the three needles.


Characterization of wear of tungsten carbide burs.

On the basis of this study, the following conclusions can be made:--Although the primary cause of the diminution of cutting efficiency when composite restorations are cut is due to abrasion, a secondary cause is the adhesion of the melted resin to the flutes.--Amalgams and tooth structures cause significantly less wear to burs than composite restorations.--The design of burs currently used is probably a poor choice to remove composite restorations.


C-shaped canal configurations in mandibular molars.

Three cases of C-shaped mandibular second molars are described. These clinical findings were similar for each case:--It was impossible to diagnose the condition on the preoperative radiograph.--All three cases had normal anatomy of the pulp floor and separate canal orifices.--Continuous hemorrhage and sensitivity were encountered when instruments were used.


Fc receptors on myeloid leukaemic cells: comparison between assays of rosette-forming cells.

A comparison has been made between assays of Fc receptor bearing cells among blood leucocytes from normal individuals and from patients with myeloid leukaemia, using human anti-D coated erythrocytes (HEA) and sheep erythrocytes sensitised with a rabbit anti-sheep erythrocyte antibody (SEA). Differences were found between the assays in both groups, demonstrating the heterogeneity of Fc receptors with respect to affinity for marker, and for Fc bearing leucocytes. Monocytoid cells reacted more readily with both markers than myeloid cells. The HEA rosette assay may be useful selective diagnostic aid for Fc+ myeloid leukaemia since the SEA assay detects Fc receptors on mature granulocytes.


[Isothermal ordering processes of equiatomic alloy CuPt (author's transl)].

Isothermal ordering processes of equiatomic alloy CuPt quenched from above the critical temperature were investigated by means of electrical resistivity measurements, X-ray diffraction and electron microscopic observations. The main results obtained are as follows; (1) two different orderings are recognized at above and below 560 degrees C. Each main reaction is an ordering process having the activation energies of 30.6 and 17.4 kcal/mol, respectively. (2) In the early stage of ordering at the temperature below 200 degrees C the growth of disperse order is recognized by the increment of electrical resistivity, and has an activation energy of 30.1 kcal/mol. (3) At the temperature between 300 degrees C and 560 degrees C, the process of ordering consists of three stages having an activation energy of 17.4, 23.6 and 65.3 kcal/mol, respectively. These correspond to the ordering processes by the migration and the annihilation of quenched-in excess vacancies, the annihilation of secondary defects and the diffusion of equilibrium vacancies, respectively. (4) At the temperature above 560 degrees C, the process of ordering consists of two stages. The bulk of the ordering is a homogenous ordering within the grain.


[Order-hardening in equiatmic alloy CuPt (author's transl)].

The order-hardening and its modes of equiatomic alloy CuPt were investigated by means of hardness test, X-ray diffraction and optical microscopic observations. The important results obtained are as follows; (1) Two different modes of order-hardening are recognized, namely at the temperature ranges of 400 degrees C-550 degrees C and 600 degrees C-700 degrees C. (2) The activation energies for order-hardening at lower and higher temperatures are 19.3 and 31.1 kcal/mol, respectively. The former corresponds to the migration and the annihilation of quenched-in excess vacancies, the latter corresponding to the growth of ordered domain. (3) Heterogeneous ordering along the grain boundary at lower temperature and homogeneous ordering within the grain at higher temperature are the dominant reaction for hardening. But the ordering is achieved by the nucleation-and-growth process at all temperature.


[Properties of polyfluoroethylene-copolymers for the denture base lining material (author's transl)].

Silicone rubber is conventionally used as a lining soft material for denture base. However it still has some properties to be improved, such as poor adhesive strenth with acrylic resin, discoloration, degradation and growth of candida. We attempted to apply chemically-stable polyfluoroethylene-copolymers for this purpose. The terpolymers consisting of difluoroethylene, tetrafluoroethylene and chlorotrifluoroethylene (or hexafluoropropylene) were prepared and tested for tensile strenth, adhesive strength to acrylic resin, water sorption, contact angle, shore hardness, and toxicity by hemolysis test, cell culture test and extraction test. One of the selected terpolymer showed less water sorption (0.1 mg/cm2), stronger tensile strength (160 kg/cm2) and adhesive strength (110 kg/cm2) than the silicone rubber lining material. The toxicity test results suggested that the terpolymer will pose a low potential acute toxicity in vivo. All the test results seem to suggest that the polyfluoroethylene elastomer described here is a promising soft liner material for denture base.


[Analysis of eluate extracted from dental filling resin by high performance liquid chromatography (author's transl)].

Since the residual monomer of cured filling resin has been implicated in toxicological effects, a high performance liquid chromatography (HPLC) was used to analyze the eluate of bisphenol A diglycidylmethacrylate (Bis-GMA) and methyl methacrylate (MMA) type resins presently used. The main chemicals of the eluate from resin into three kinds of solution, water, 85% methanol water solution and 100% methanol were the residual monomers which formely were Bis-GMA, triethylenglycol dimethacrylate and latterly MMA. Residual initiators, benzoyl peroxide and hydroquinone were also determined. This investigation has  shown that HPLC is rapid, reliable and an acurate method to analyze the residual monomers of cured dental filling resins.


[Thermal behavior of gypsum bonded investments. (Part I) Thermal behavior in heating process(author's transl)].

The cause of the three shrinkages in the thermal expansion curves of gypsum bonded investments, which were characterized in the previous study, was examined mainly by means of TG-DTA method, X-ray diffraction method and SEM observation. The main results were as follows: 1. The first shrinkage between 100 degrees C and 200 degrees C was caused by the dehydration of gypsum. 2. The second shrinkage between 300 degrees C and 400 degrees C was due to the transformation of soluble anhydrite to insoluble anhydrite. 3. The third shrinkage beginning at the temperature range 700 degrees C approximately 800 degrees C is considered to be related to the sintering of insoluble anhydrite.


[Thermal behavior of gypsum bonded investments. (Part 2) Sintering phenomena of set plaster (author's transl)].

The sintering phenomena of set plaster on the heating process have been investigated by measuring shrinkage and apparent density and by observing the structure of fractured surface with SEM. As a result, it was found that the sintering shrinkage occurred in two stages for the temperature range from 500 degrees C to 900 degrees C. In the first stage between 500 degrees C and 800 degrees C, the skelton of needle-like crystals of gypsum remained and micro-grains were observed in it. In the second stage between 800 degrees C and 900 C, the skelton disappeared and the grain growth was remarkable. In addition, the rate of shrinkage was slow in the first stage, and was very fast in the second stage.


[Thermal behavior of gypsum bonded investments. (Part 3) Sintering kinetics of insoluble anhydrite (author's transl)].

The sintering kinetics of insoluble anhydrite were studied by measuring the isothermal shrinkage of compacts of insoluble anhydrite powders in air. The sintering process of insoluble anhydrite powders consisted of two stages for the temperature range from 630 degrees C to 720 degrees C. The first shrinkage could be described as a bulk diffusion model and followed the equation delta L/Lo infinity t 0.5l +/- 0.08, where delta L/Lo is fractional shrinkage and t is the sintering time. The apparent activation energy of the shringage was 130 kcal/mole. The second shrinkage followed the equation delta L/Lo infinity t 1.83 +/- 0.30, but could not be explained with reasonable model. However, the SEM observations of the fractured surface of compacts suggested that the second shrinkage corresponded to the grain growth of insoluble anhydrite.


[Studies of dental methacrylic resin. (Part. 6) Adhesive strength of self-curing methacrylic resin to polymethylmetacrylates with various cross-linking density. (author's transl)].

The adhesive property of dental acrylic resin to resin teeth and denture base resins is an important property, in the case of preperating, repairing and rebasing denture. Then, as models of denture base resin and resin tooth, heat-curing methacrylic resins which were cross-linked with three kinds of polyethylene glycol dimethacrylate, i.e., EDMA, tri-EDMA, nona-EDMA, were prepared, and the tensile adhesive strengths of self-curing methacrylic resin to them were examined. The results were as follows. 1) The tensile adhesive strength under the dry condition was dependent on cross-linking density of adherent resin, and decreased according to the increase of concentration of cross-linking agent added in adherent resin. 2) The greater the number of chain members of cross-linking agent used to adherent resin was, the higher the adhesive strength was. In particular, the adhesive strength to adherent resin added with nona-EDMA in concentration from 16.7 to 30 mole%, agreed with the tensile strength of adherent resin itself indicating a favourable adhesion. 3) The adhesive strengths under the wet condition, that is, when specimens were immersed in water at 37 degrees C for 21 days, decreased from 30 to 50%, compared with that under the dry condition.


[Studies of dental methacrylic resin. (Part 7) Adhesive strength of fluid methacrylic resin to polymethylmethacrylates with various cross-linked density (author's transl)].

Heat-curing methacrylic resins cross-linked with three kinds of dimethacrylates, i.e. EDMA, tri-EDMA and nona-EDMA, were prepared, and the tensile adhesive strength of fluid methacrylic resin to them was examined. The results obtained were as follows. (1) To adherent resin cross-linked with EDMA, the adhesive strength of fluid resin showed the maximum at the concentration near 2 mole% and decreased with increasing the concentration. (2) To adherent resin cross-linked with tri-EDMA or nona-EDMA, the effect of the concentration of cross-linking agent on the adhesive strength was little, except that the adhesive strength to the latter adherent resin showed a steep increase in the range of lower concentration. (3) The adhesive strength did not appreciably change in the range of L/P ratio of fluid resin from 0.57 to 0.71 ml/g. (4) The adhesive strength under the wet condition decreased about 40 to 50% compared under the dry condition. (5) To cross-linked adherent resin, the adhesive strength of fluid resin was somewhat higher than that of self-curing resin under the dry condition. But, under the wet condition this difference was little. (6) Contrarily, to non-cross-linked adherent resin, the adhesive strength of fluid resin was somewhat lower than of self-curing resin. This may be because the cracks, which are occured on the surface of non-cross-linked adherent resin by contact with abundant MMA of fluid resin, work as defects to decrease the adhesive strength.


Onset of genetic obesity in the absence of hyperphagia during the first week of life in the Zucker rat (fa/fa).

The aim of this study was to discover which of three major abnormalities of the genetically obese Zucker rat (fa/fa), namely hyperphagia, excess adiposity, and hyperlipidemia, is the first to appear prior to manifest obesity, i.e., before weaning. Suckling fa/fa rats, bred from heterozygous parents, were detected by sizing fat cells obtained from an inguinal fat pad biopsy. Cell hypertrophy was observed in fa/fa rats, compared to Fa/-littermates of the same sex, as soon as 5-7 days after birth. Prediction of fa/fa genotype at this age by this method was assessed using a series of 80 pups and proved to be totally successful. The identity of the "predicted" obese pups was confirmed morphologically at 6 weeks of age. Food (milk) intake was estimated from water turnover rates determined on 86 pups aged 2-8 days using tritiated water. The results show that 7-day-old fa/fa rats had heavier inguinal fat pads with larger adipocytes and higher lipoprotein lipase activity than their lean controls. There was no genotype effect on water intake adjusted to body weight during the first week of life. Moreover weight of stomach contents and triglyceridemia were similar in all animals at 7 days. These results show that excess adiposity develops in the fa/fa rat during the first week of life, before hypertriglyceridemia and hyperphagia, and raises the question of whether this adiposity results from a defect in energy expenditure or an abnormality of fat cell storage capacity, or both.


Cholesterol, phospholipids, and fatty acids of normal immature neutrophils: comparison with acute myeloblastic leukemia cells and normal neutrophils.

The lipid composition of immature myeloid cells from the bone marrow of normal persons and myeloblasts from patients with acute myeloblastic leukemia was studied and compared with the lipid composition of normal mature human neutrophils. Total cholesterol, phospholipid, and fatty acid composition was determined on each cell type. The leukemic cells showed decreased total cholesterol and cholesterol-to-phospholipid ratio, increase phosphatidylcholine and phosphatidylinositol, decreased phosphatidylethanolamine, and an increased percentage of unsaturated fatty acids when compared to normal mature neutrophils. A nearly identical pattern was seen in the normal immature myeloid precursors from normal bone marrow. We conclude that the altered lipid composition of acute myeloblastic leukemia cells is related to unexplained factors related to cell age and not to malignancy per se.


Enhancement of ionizing radiation effect on the testes of rats by microwave or ultrasound-induced hyperthermia.

Hyperthermia induced from microwave 30 watts for 5 minutes or from ultrasound 1 watt/cm2 for 5 minutes as well as x-rays were destructive to the testes of rats. The combination of x-ray and hyperthermia enhanced the destructuve effect regarding the degree of reduction of spermatogenesis as well as the number of tubules affected.


The importance of etiology for the successful treatment of secondary trigeminal neuralgia. Reviews of some clinical cases.

Incorrect etiopathological evaluation of trigeminal neuralgia could result in therapeutic mistakes. Some of the clinical cases encountered are reviewed to point out diagnosis leading to valid therapeutic approaches.


Alterations of host defenses paralleling cholesterol-induced atherogenesis. I. Interactions of prolonged experimental hypercholesterolemia and infections.

Cholesterol may interfere with normal repair processes in the arterial wall. It is also possible that this same action occurs during inflammation and repair throughout the body. This hypothesis was tested by giving intravenous injections of Bacteroides fragilis, a bacterium that is innocuous for normal rabbits even when multiple large doses are given. Almost all cholesterol-fed rabbits developed significant pleuropulmonary infections with complications that included vasculitis, thrombosis, extrapulmonary infections, and significant mortality. More than half of this group was culturally positive for B. fragilis at the time of autopsy while cultures from control animals were sterile. These results suggest that cholesterol may interfere with the functions of those cells involved in host defense.


A multicenter study for analgesia involving fenoprofen, propoxyphene [alone or in combination] with placebo and aspirin controls in postpartum pain.

One investigator at each of 4 institutions followed the requirements of a core protocol designed to evaluate propoxyphene napsylate (50, 100 and 150 mg), fenoprofen calcium (200, 400 and 600 mg) and their combination (50/200, 100/400 and 150/600 mg) in patients reporting postpartum pain. Placebo and aspirin (650 mg) were included as control medications. Analyses were based on subgrouping which isolated individually the interactions between medications and the following factors: dose-observation criteria, the investigator-observer-institution differences, the intensity of pain at the time the medication was given, and postepisiotomy-wound compared to uterine-cramp pain. Each of these factors influenced the absolute scores for analgesia significantly, but had no significant influence on the relative rankings of the medications. The analgesia scores for individual patients in each subgroup were transformed to ridits and then pooled. A linear increase in effectiveness occurred in response to increasing doses of propoxyphene, fenoprofen, and their combination in this dose range. The dose responses were essentially parallel. The combination was more effective than either drug alone.


Diurnal variations in plasma insulin concentrations in normal and cirrhotic subjects: effect of dietary protein.

Concentrations of immunoreactive insulin and of glucose were measured in plasma samples taken at 4-hour intervals from cirrhotic and normal control subjects ingesting diets containing various amounts of protein. In both groups, insulin levels were highest after meals, between 11 a.m. and 7 p.m.; in cirrhotic subjects, but not in controls, plasma glucose levels were also higher at these times. Insulin and glucose concentrations in plasma from cirrhotic subjects were higher than those from control subjects at all times measured. Peak daytime insulin levels were about 150 muU/ml in plasma from cirrhotic subjects, and 40--50 muU/ml in plasma from controls; nocturnal levels were 20--30 muU/ml in cirrhotics versus 10 muU/ml or less in controls. The protein content of the diet was unrelated to plasma insulin levels at all times of day or night examined. These data thus show that plasma insulin levels are persistently elevated in cirrhotics, remaining higher than normal throughout the 24-hour period.


The effect of selective monoamine oxidase inhibitors, clorgyline and deprenyl, upon tissue glycogen stores and blood glucose levels.

The effect of selective monoamine oxidase (MAO) inhibitors clogyline and deprenyl upon glycogen stores in brain, heart and liver and upon blood glucose were examined for a possible link between the activity of the oxidase and metabolism of carbohydrates. The experiments were performed in normally fed rats and rats subjected to starvation for 24 hours. This study showed that selective inhibitors of MAO affect carbohydrate metabolism and that this may be the consequence of increased monoamines in the organs and circulation. However, there was no correlation between the selective inhibition of a particular form of MAO and glycogen metabolism.


Toxic delirium after L-dopa medication.

L-DOPA-psychosis is a frequent side effect of the combined treatment of Parkinson's disease with L-DOPA and peripherally active decarboxylase inhibitors. Regional human post-mortem brain studies showed a significant increase of noradrenaline and serotonin particularly in extrastriatal areas, whereas the lenticular nuclei were not involved. The significance of extrastriatal neurotransmitter dysfunctions for psychiatric disorders is discussed.


Pathophysiology of delirious states.

MHPG concentration in CSF, urinary excretion of NA and A as well as activity of serum DBH were significantly elevated during alcohol delirium as compared to the recovery period. Urinary DA and HVA in CSF did not show any constant change. One single dosage of clozapine (100 mg orally) induces higher urinary NA and A excretion. There is a time course of clozapine action. MHPG in rat brain a single dosage (50 mg/kg) is elevated; after repeated administration (11 days) a decrease is observed. After 10 days of treatment with clozapine (300 mg/day) a decrease of MHPG in CSF can be seen. It is hypothesized that there is a relationship between delirious states and increases central NA turnover.


Brain energy metabolism and catecholaminergic activity in hypoxia, hypercapnia and ischemia.

A brief review is given of recent results which indicate that several stressful situations are accompanied by an increase in cerebral metabolic rate, mediated by extrinsic or intrinsic catecholamines. These situations include withdrawal of nitrous oxide supply in paralyzed animals ("immobilization stress"), amphetamine intoxication, hypoxia, and hypercapnia. Studies of hypercapnia (and hypoxia) suggest that activity in cerebral noradrenergic systems is enhanced by cellular acidosis. Data obtained during recirculation, following severe, transient ischemia, indicate that in spite of a general depression of cerebral metabolism (and neuronal function) some neuronal systems, notably the noradrenergic ones, show evidence of increased activity.


Cerebrospinal fluid homovanillic acid in cerebral infarction.

Cerebrospinal fluid (CSF) homovanillic acid (HVA) concentration was measured in 39 consecutive cases of hemispheric infarction, 7 cases of brainstem infarction, and in 16 controls. The CSF-HVA level was 38 +/- 15 ng/ml (mean +/- S.D.) in the control patients, 15 +/- 6 ng/ml in patients with brainstem infarcts, and 49 +/- 41 ng/ml in those with hemispheric infarcts. The CSF-HVA levels were decreased in brainstem infarct cases (p less than 0.001) and greatly scattered in patients with hemispheric infarcts (range 4--207 ng/ml) when compared to controls. The decrease of levels of CSF-HVA in brainstem infarct cases may reflect interference with the dopaminergic pathways. CSF-HVA values in hemispheric infarction could not be related to the acuteness, location, nor severity of the lesion. The broad range of CSF-HVA values may be due to the interaction of multiple, as yet unknown factors. These findings suggest that dopamine metabolism is altered in many cases with acute brain infarction.


Cerebrovascular changes in migraine: secondary manifestations of a circulating humoral agent?

The cerebrovascular concomitants of migraine, initial vasoconstrictriction succeeded by vasodilatation, have long been considered the primary event in the pathogenesis of headache. In recent years, certain physicochemical concomitants of the attack have been identified, all involving blood platelets: these include hyperaggregability, decrease 5-hydroxytryptamine concentration and decreased monoamine oxidase activity. These changes may represent the response to a circulating humoral agent, deriving perhaps from the pulmonary vascular bed. The agent may not only bring about nonspecific damage of the kind described but be responsible for the cerebrovascular changes and stimulation of pain receptors characteristic of the disease. This circulating humoral agent may belong to the prostaglandin family.


Brain energy metabolism and alterations of transmitter profiles in acute hepatic coma.

Brain energy reserve, tricarboxylic cycle intermediate and some putative neurotransmitters were measured in a devascularisation model with portacaval shunt and hepatic artery ligation done in two interventions. Conditions were standardized in that physiologic parameters, i.e. body temperature, systemic arterial pressure, PO2, PCO2 and pH, were kept constant and brain tissue was obtained with the "freeze-blowing" technique designed for deep freezing brain substance in less than one second. 1. Measured values indicative of the brain energy reserve (glucose, glycogen, ATP and phosphocreatin) were not found to differ from those of sham-operated animals. 2. Of the stimulating neurotransmitters, norepinephrine, dopamine, glutamic acid and aspartic acids were reduced with the exception of acetylcholine among the inhibitory neurotransmitters GABA and cAMP were unchanged, while all others including serotonin, octopamine, and phenylethanolamine were increased. 3. The results of these experiments suggest that an inbalance of amino acids with resultant changes in neurotransmitter profiles rather than an energy deficit constitutes the factor underlying hepatic coma.


Effects of portocaval anastomosis on behaviour and brain tryptophan metabolism.

The rat with portocaval anastomosis represents a convenient took for the investigation of (a) factors determining the availability of tryptophan to the brain and (b) the role, if any, that altered tryptophan metabolism may have in the development of hepatic encephalopathy. It was found that increases in brain tryptophan following anastomosis paralleled plasma free tryptophan rather than plasma total tryptophan regardless of whether or not correction for inhibition from amino acids competing with tryptophan for uptake into brain was applied. Nevertheless, while plasma free tryptophan exerts a major influence on brain tryptophan in both sham-operated and anastomosed rats, in the latter group brain tryptophan is raised further by some other mechanism. The anastomosed rat was also found to be behaviourally abnormal in a number of test situations. Thus, they were hypoactive during chronic exposure to an open-field and were less responsive to electric shock. Following the administration of tryptophan, sham-operated rats were also less active in an open-field and less responsive to electric shock when compared with saline-treated rats. Thus, anastomosed rats have behavioural abnormalities for which altered tryptophan metabolism might, to some extent, be responsible.


Tryptophan in hepatic coma.

The concentrations of tryptophan in serum and CSF, as well as that of 5-HIAA in CSF were investigated in various group of patients. Those with hepatic cirrhosis have normal total serum tryptophan. However, because of the low concentration of serum albumin the percentage of nonalbumin-bound tryptophan is elevated about 50 percent above the mean control value. By contrast tryptophan in the CSF was increased by 50 to over 800 percent. This suggests that there is also an increase in brain tryptophan and serotonin in the cirrhotic patients. No significant difference was found for the concentrations of tryptophan in CSF of patients in coma and those not in coma. Patients with hepatic coma had an elevated concentration of 5-HIAA in the lumbar CSF which may reflect the increase in this compound and in serotonin reported by Jellinger and Riederer (1977). However, following treatment with probenecid in order to block the egress of 5-HIAA from the CSF, the concentration of 5-HIAA in relation to that of probenecid was not significantly different for the group with hepatic coma as compared with the control group.


Plasma amino acids in hepatic encephalopathy.

In 75 cases of histologically verified liver cirrhosis the plasma amino acids were determined by ion exchange chromatography and the results were correlated with different liver function tests as prothrombin time, pseudocholinesterase, serum albumin, GOT, bilirubin and venous ammonia. Out of these parameters prothrombin time, pseudocholinesterase and serum albumin significantly correlated with the sum of branched-chain amino acids and with the Fischer's quotient (molar ratio of branched-chain and aromatic amino acids). Methionin and aromatic amino acids inversely correlated with these parameters, additionally methionin positively correlated with bilirubin and GOT. By comparing plasma amino acid levels in cirrhotics without and with hepatic encephalopathy (grade 3 or 4) no significant differences were found. "Fischer's quotient" showed an overlap in patients with and without encephalopathy. Therefore the precipitation of hepatic encephalopathy is not fully explained by the changes in plasma amino acids. Therapeutic administrations of specially mixtures of amino acids with a high content in branched-chain and a low content in aromatic amino acids correct the plasma amino inbalance for a short time and improves hepatic encephalopathy.


The effect of serotonin on the blood-brain barrier to proteins.

Since increased concentration of serotonin (5-HT) has been demonstrated in areas of the brain exposed to ischemia and lesions, and since the elevation might be responsible for the enhanced permeability to proteins across cerebral vessels, studies were carried out to elucidate the effect of the amine, perfused through the cerebral ventricular system, on the transport of horseradish peroxidase (HRP) from blood to brain. The amounts of 5-HT were large (50--800 microgram per mouse). The permeability across cerebral vessels was increased, especially across arterioles. The endothelium was intact. HRP did not form a continuous line between endothelial cells, from the vessel lumen to the subendothelial basement membrane. Furthermore, channels through the endothelium, that could allow HRP to pass, were not observed. However, several vesicles, filled with HRP were observed in the cytoplasm of endothelial cells. They could be open to the vessel lumen or to the subendothelial basement membrane. Freely situated HRP-containing vesicles were also found. Based on the observations it is most reasonable to assume that the 5-HT, perfused through the cerebral ventricles increased the normally occurring vesicular transport of protein from blood to brain.


Human cerebral free amino acids in hepatic coma.

Free amino acids and some related compounds in autopsy specimens of different human brain areas have been determined by column chromatography. Only in patients with hepatic coma could a significant difference in the contents of tyrosine and lysine between caudate nucleus and N. amygdalae be found. In comparison with control subjects the brains of patients with hepatic coma contained significantly higher concentrations of glutamine, isoleucine, histidine and ammonia. In patients with hepatic coma after complete parenteral nutrition plus L-valine administration, dying from other causes, the brain levels of alanine and valine were decreased, while the content of taurine was significantly increased. However, most of the amino acid levels in brain tended toward lower levels. A very significant reduction after treatment with L-valine could be observed in glutamine and ammonia concentration. It is suggested that L-valine has some beneficial action on ammonia detoxification and has also a competing action on amino acid uptake mechanism (specially with the large neutral amino acids).


Interaction between parallel transport systems examined with tryptophan and related amino acids.

Most of the neutral amino acids are transported across the plasma membrane by two or more parallel transport systems. In this study, we have limited transport interactions to System A and L by studying amino acids not transported by System ASC. Results are presented to emphasize that such amino acids as leucine, phenylalanine and tryptophan do enter the Ehrlich cell to substantial degrees by System A. We show how the phenomenon of competitive stimulation presents a strong argument that these systems operate between the same two compartments, extracellular and cellular. To discover what is needed to bring two amino acids into the transport relation shown by tryptophan and methionine, we arbitrarily set up two classes of amino acids: (1) those whose steady-state gradients will be increased when System L is deleted; (2) those whose gradients will instead be decreased. On blockading System L with 2-aminorbornane-2-carboxylic acid applied in symmetry to the two sides of the plasma membrane, we show as predicted that the gradient maintained for methionine is strongly increased, that for trypotphan decreased. The initial rate of uptake of all the amino acids mentioned is highly sensitive to the nature of the cellular amino acid pool. A high influx by exchange, relative to net influx, appears to characterize the amino acids that respond to competitive stimulation. Albumin-bound tryptophan appears not directly accessible to the tested carriers.


Kinetics of tryptophan transport into the brain.

Tryptophan is transported into the brain by a complex system, experimental and kinetic analysis of which favours a carrier mechanism functioning in association with diffusion (3-paramater model), as distinct from a system comprising two carriers (4-parameter model). The Lineweaver-Burk method is limited as a means of distinguishing between these alternative models. A statistical (linerization) technique represents an improvement over the graphical method in providing the best estimates of the parameters, as well as a measure of the variance (error mean square) of each fit to the data. However, even with this a distinction between alternative models ultimately depends upon analysis of a variety of kinetic experiments.


Structural specificity of the carrier for L-tryptophan in rat cerebral cortex slices.

The effect of a number of commonly occurring amino acids as well as metabolites originating in the pyrrolase pathway of tryptophan catabolism and in the serotonin pathway have been studied with regard to their effect on the net flux of tryptophan into rat brain cerebral cortex slices. Phenylalanine, p-chlorophenylalanine, tyrosine, 3,4-dihydroxyphenylalanine and kynurenine as well as leucine, isoluecine and valine all inhibited the net uptake of tryptophan. It was concluded from these studies that tryptophan is transported into the cell via the large neutral amino acid carrier. Compounds lacking the aliphatic side chain carboxyl or alpha-amino group have no action on tryptophan transport.


Interactions between tryptophan, phenylalanine and sugar transport in the small intestinal mucosa.

The kinetics of the influx of tryptophan and phenylalanine into guinea-pig intestinal rings have been examined. The transfer of these two amino acids can be described by a single transport system, each amino acid having an affinity constant, Kt, of about 4 mM for the influx mechanism. Mutual inhibition studies have shown that the inhibitory constant of each of the amino acids is also 4 mM. Although fully competitive inhibition between the two amino acids occurs, the inhibition of the influx of the amino acids by sugars exhibits kinetics of the "pseudo-competitive" type. Such behaviour is compatible with an allosteric interaction between two different binding sites, one for each class of compounds. The lack of correlation between the inhibitory potency of a given sugar and its rate of transfer, as testified by a comparison of the effects of galactose and beta-methyl-glucoside on phenylalanine influx, can be reconciled with the "allosteric-interaction hypothesis", but specifically repudiates any theory that attempts to explain such interactions in a way that requires such a correlation. The fact that allosteric interactions are retained in cells preloaded with sodium also precludes a primary role for sodium in the mechanism of such interactions.


Transport of tryptophan and other amino acids by mammalian erythrocytes.

Mammalian erythrocytes are known to have 4 distinct amino acid transport systems. The C system is found in sheep erythrocytes and is specific for neutral amino acids of intermediate size. Human cells lack the C system and have two alternative neutral amino acid transport mechanisms: the L system which is selective for large hydrophobic amino acids and a Na-dependent alanine-cysteine system. The L system is absent from ruminant and cat erythrocytes. Human rabbit and cat cells, but not sheep erythrocytes, have a specific dibasic amino acid transport mechanism (Ly system). L-Tryptophan uptake by human erythrocytes is mediated by two routes: a saturable high-affinity transport mechanism selective for L-tryptophan and a low affinity uptake mediated by the L system. The saturable component of L-tryptophan transport occurs by a previously unidentified uptake system, and is the major route for L-tryptophan uptake at physiological substrate concentrations. This system is absent from sheep and cat erythrocytes.


A comparison of amino acid transport and ouabain binding in brain endothelium and salivary epithelium studied in vivo by rapid paired-tracer dilution.

Amino acid tmransport at the luminal side of brain capillary endothelium and the basal side of salivary epithelium were compared using a nondestructive, first-circulation, paired-tracer dilution method. In the brain, the reference molecule was an intravascular marker (Crone's method) whereas inthe salivary gland the reference was an extracellular marker of similar size to the test molecule. The unidirectional flux was related to a maximal uptake, U: U = 1 --test concentration/reference concentration Uptake and cross-inhibition experiments in brain suggest the presence of only a long-chain neutral L-amino acid transport system (leucine, phenyl-alanine, tryptophan, tyrosine, valine, methionine). In contrast, results in the salivary gland suggest 4 transport systems: 1. large neutral, 2. small neutral (alanine, serine), 3. basic (lysine) and 4. acidic (aspartic, glutamic). The same method was applied to localize binding sites. Ouabain bound very significantly to the salivary epithelium but not at all to the brain endothelium. The method described is of interest since it can be extended to any organ and possibly to man.


Zero-trans uptake of L-tryptophan in the human erythrocyte.

Some results from ongoing studies of the transport of some neutral amino acids across the human erythrocyte membrane (L-tryptophan and L-leucine) at 25 degrees C are presented. The unidirectional flux into the cell at initial rate as a function of the substrate concentration can be described by a 3-parameter model (i.e. a carrier in parallel with an apparent leak component). From the estimated kinetic parameters an apparent membrane permeability of the carrier (substrate concentrations S1 smaller than Kzt 12) has been calculated. The permeability of L-tryptophan (1.03 . 10(-8) cm/sec) was significantly lower than the permeability of L-leucine (2.36 . 10(-7) cm/sec). The contribution of the leak permeability to the total permeability at low concentrations was about 10% for L-tryptophan, but only 1% for L-leucine. From inhibition studies it is indicated that L-tryptophan passing the membrane via theapparent leak component is transported by the L-leucine carrier, the affinity being low. The saturable component of L-tryptophan transport does not correspond to any known amino acid transport system, and it is thus strongly suggested that a new L-tryptophan specific transport system operating at physyological concentrations has been described.


Tryptophan accumulation by blood platelets of depressed patients.

The accumulation of tryptophan by blood platelets has been investigated in depressive patients and controls using short incubation times and low substrate concentrations. The accumulation of tryptophan by the platelet is significantly greater in the acutely depressed patients than the control group. The results are discussed with reference to tryptophan transport in depression and also to the regulation of plasma levels of tryptophan.


Distribution of tryptophan in erythrocytes, leukocytes and thrombocytes, and its binding to plasma albumin.

The extended theory about a dysfunction of the serotoninergic system in depression and schizophrenia includes the hypothesis of a disturbance in the transport systems of tryptophan and tyrosine from blood to brain. It would be interesting to know if blood cells may be used as a model for the central transport mechanisms of these amino acids. After an oral load, the in vivo distribution of L-tryptophan (50 mg/kg) was studied in the blood plasma, in the different blood cells and its binding to plasma albumin, in six healthy, seven schizophrenic and two depressive subjects. In all the compartments studied, tryptophan reached a peak, 1--2 hours after the load. Before and after the load, the variation of the tryptophan concentration in the erythrocytes was parallel to the plasma free tryptophan, whereas the uptake of this amino acid was higher in leukocytes and thrombocytes than in erythrocytes. However, this model does not show differences between schizophrenic and normal subjects with regard to the transport of tryptophan and tyrosine in these cells.


The influence of oral tryptophan on cortical evoked responses in normals and schizophrenics.

The cortical evoked responses to sensory stimulation were studied in order to evaluate the central effects of oral tryptophan in normals and schizophrenics. In the first study, seven volunteer male students were tested during four experimental sessions. Visual evoked responses to flashes were recorded at occiput and vertex, before and 1 1/2 hours after the ingestion of 35 mg/kg tryptophan in apple purée with 50 g glucose or placebo. Some significant modifications of evoked responses were observed after tryptophan ingestion: a decrease of amplitude and an increase of variability. The latencies were rather stable, presenting only minor modifications. From these results, corroborated by some data from literature, it may be supposed that tryptophan induces a decrease of arousal. In the second study, seven chronic schizophrenics and 6 volunteer controls were tested, using an analogous experimental design, however with some modifications: the tryptophan dose was increased to 50 mg/kg and administered in 200 ml of milk, instead of apple purée with glucose. The modifications of evoked responses recorded in the preceding study were no longer found. Probably, the substitution of milk for glucose resulted in an alteration of the transport of tryptophan across the blood-brain barrier. The blood parameters were rather similar in the two studies; therefore, the central effects of tryptophan did not parallel its blood levels.


Blood-brain movements of tryptophan and tyrosine in manic-depressive illness and schizophrenia.

In order to investigate possible disturbances of the blood-brain transport mechanisms of monoamine precursors in manic-depressive illness and schizophrenia, we have measured the brain arterio-venous difference of DOPA, or 5-HTP, or tyrosine and tryptophan in 36 patients, during the infusion of either L-DOPA or L-5-HTP. The infusion lasted for 30 min, and blood was sampled during and immediately after the infusion, simultaneously in the femoral artery, the jugular vein and a vein of the arm. During the infusion of L-DOPA, manic patients have a higher extraction of L-DOPA than depressive patients and controls. During the infusion of L-5-HTP, pdpressive patients have a higher brain extraction of 5-HTP than manic or schizophrenic patients. In depressive patients, a small uptake of tryptophan correlated with a large outflow of tyrosine was observed. The opposite was seen in manic patients, with an outflow of tryptophan correlated with an uptake of tyrosine. In schizophrenics, there was an outflow of tryptophan and random variations of tyrosine. These brain arterio-venous differences were not correlated with arterio-venous differences for peripheral tissues. Taken together, these results are compatible with a disturbance of the blood-brain transport of amino acids precursors of monoamines in manic-depressive illness and schizophrenia.


Distribution of tryptophan and tyrosine in unipolar affective disorders as defined by multicompartmental analysis.

As requirements for tryptophan for synthesis of protein and 5-hydroxytryptamine were comparable in rat brain, during depletion of tryptophan there could be competition between the two pathways for the amino acid. This implied that tryptophan should be rate-limiting for protein synthesis and this was found in the short term when concentrations of the amino acid were reduced in rats. Multicompartmental studies of tryptophan and tyrosine in controls and patients subject to unipolar depression defined two main pools of the amino acid provisionally assigned to extracellular and intracellular spaces. For tyrosine, mean values for the extracellular space were comparable to those of controls. The concentration of tyrosine was low in the intracellular space in both depressed and recovered patients, but the raised fractional clearance rates for this compartment during depression had returned to normal on remission. Plasma tryptophan concentrations were significantly reduced in depression with intermediate values after recovery. This suggested that the procedure used may have been mildly stressful and that this had evoked an idiosyncratic response to the stress in the depressed patients, which was characterized by inability to maintain concentrations of this amino acid in plasma. The findings for both amino acids may have a bearing on the aetiology of unipolar affective disorder.


Serotonergic mechanisms in myoclonus.

Post-hypoxic intention myoclonus is a specific myoclonic syndrome in which central serotonergic tone may be deficient. Tryptophan and 5-hydroxytryptophan administration to patients with post-hypoxic intention myoclonus increases pre-existing low levels of 5-hydroxyindoleacetic acid levels in the cerebrospinal bluid, and also suppresses myoclonus. Serotonin precursor administration does not help all patients with myoclonus and may actually worsen some myoclonic syndromes, including those secondary to lipid storage diseases. Treatments that alter serotonin metabolism can also produce myoclonus in experimental animals but their relevance to myoclonic syndromes in humans remains uncertain.


Kinetics of tryptophan transport across the blood-brain barrier.

The transport of tryptophan across the blood-brain barrier in vivo has been analyzed kinetically to assess the influence upon it not only of the concentration of tryptophan in the blood plasma, but also of the inhibitory effect of fourteen other amino acids normally present in the circulation. The transport of tryptophan into the brain conforms to the equations of enzyme kinetics with competitive inhibition, provided appropriate modifications are made to take account of a non-saturable component (possibly passive diffusion) in the transport, and of the normal presence in the blood of other amino acids which act as competitive inhibitors. The inhibitor constant has been evaluated for each amino acid and in many cases it corresponds fairly closely with the Michaelis saturation constant for that amino acid, suggesting that tryptophan and these inhibitors share a common transport carrier. The implications of the kinetic analysis are considered for hormonal and metabolic disturbances which change the proportions of amino acids in the blood. The effect of an increase in competitive inhibition due to raised levels of amino acids is to make the tryptophan influx more directly dependent upon the level of tryptophan in the blood.


Diet-induced changes in plasma amino acid pattern: effects on the brain uptake of large neutral amino acids, and on brain serotonin synthesis.

Tryptophan is transported into brain by a competitive carrier system it shares with such other large neutral amino acids as tyrosine, phenylalanine, leucine, isoleucine, and valine. Physiologic variations in the plasma neutral amino acid pattern (either as a change in plasma tryptophan, or in the plasma concentration of one or more of its competitors) directly alter this competitive process, and thereby modify the uptake of tryptophan into brain. Such variations in tryptophan uptake influence brain tryptophan levels, and thus serotonin synthesis. Food intake, by influencing directly the plasma levels of large neutral amino acids, ca- therefore predictably modify brain trypotphan uptake and serotonin synthesis. The effect of food intake on the competitive uptake of tryptophan into brain, and on brain tryptophan levels, has recently been shown not to be limited to this amino acid, but also holds for other large  neutral amino acids, and for certain large neutral amino acid drugs (e.g., methyldopa). Hence, following a meal, the brain concentration of any large neutral amino acid appears to depend on how the food modifies the plasma level of that amino acid relative to the plasma concentrations of its competitors. The binding of tryptophan to albumin in blood has also been suggested to influence brain tryptophan uptake. However, this notion has not been sustained by the results of nutritional studies, in which meal-induced changes in brain tryptophan levels were readily shown not to be predicted by the alterations in the size of the serum free tryptophan pool. Taken together, these data affirm the importance of competitive transport in determining brain tryptophan uptake and levels, but question whether serum albumin binding and the size of the free tryptophan pool function physiologically to modulate brain tryptophan concentrations.


Relationships between plasma, CSF and brain tryptophan.

In many circumstances plasma free tryptophan correlated better than plasma total tryptophan with brain tryptophan concentration (immobilization, fasting, acute liver failure, some drugs). Also, using a modified Oldendorf method it was found that changes of plasma tryptophan binding considerably affected brain tryptophan uptake. Usually, changes of plasma tryptophan binding and non-esterified fatty acid concentration were associated. This led either to changes of plasma free and brain tryptophan concentrations (see above) or to "buffering" in which the proportion of plasma tryptophan in the free state changed but not its concentration. The plasma free tryptophan-brain tryptophan relationship was confirmed in rats after portocaval anastomosis or sham operation. In these experiments brain tryptophan changes did not correlate with plasma amino acids competing with tryptophan for transport to the brain. Determinations on plasma, lumbar and ventricular CSF from psychiatric patients suggest that plasma free tryptophan concentration provides an index of CSF tryptophan and 5-hydroxyindoleacetic acid concentrations and hence of 5-hydroxytryptamine turnover in the human central nervous system.


Ontogenesis of tryptophan transport in the rat brain.

During the first three postnatal weeks, the levels of tryptophan in the brain are exceptionally high, 2--4 times those found in adult rats. This is related to two main peculiarities concerning tryptophan transport in young animals: 1. the lack of tryptophan binding onto serum albumin which makes its diffusion from plasma to tissues easier for the  early life period; 2. the greater capacity of synaptosomes from neonates to accumulate tryptophan. Experiments consisting of electrolytic lesioning of the midbrain raphé or 5, 7-dihydroxytryptamine treatment clearly demonstrate that the uptake or tryptophan during postnatal development is not more active in serotoninergic than in other types of nerve terminals. In adult rats, changing the concentration of tryptophan induces parallel modifications in the rate of 5-HT synthesis in the brain since the rate limiting enzyme, tryptophan hydroxylase, is not saturated by its substrate. In contrast, neither tryptophan loading, nor parachlorophenylalanine administration (resulting in a marked decrease in brain tryptophan levels) alters the rate of 5-HT synthesis in the CNS of neonates, indicating that tryptophan hydroxylase is saturated during the early life period. These results are discussed in relation to the possible non-transmitter role of 5-HT during brain growth.


Facilitated healing of osseous lesions in the canine mandible after electrical stimulation.

A study was performed to investigate the effect of electrical stimulation on the repair of osseous lesions in the canine mandible. Results showed considerably more osteoblastic activity on the electrically stimulated side, with maximal growth nearest the negative electrode. Histologic examination showed healing consisted of the production of intramembranous bone, with no evidence of neoplastic changes. The practical uses of electrical stimulation in the practice of oral and maxillofacial surgery are discussed.


Arthrotomographic evaluation of the temporomandibular joint.

Thirty-five arthrotomograms of the temporomandibular joint (TMJ) were done on 33 patients who had chronic pain and dysfunction of the TMJ. All patients were refractory to conservative treatment. Five arthrotomograms were normal; abnormalities were observed in 30. Abnormalities of the meniscus were anterior dislocation, anterior subluxation, perforation, tenting, and degenerative changes and adhesions. The significance of these abnormalities is discussed. Arthrotomography was found to be an integral part of the diagnosis and treatment of TMJ disorders.


Primary tumors of the jaws in children.

Reports on primary tumors of the jaw in children are infrequent. This article reports 24 cases of primary tumors and tumor-like conditions of the jaws in children. All varieties of odontogenic and nonodontogenic tumors are seen in the jaw; fibro-osseous lesions are the most common. A possible explanation for the high incidence of mesenchymal lesions in children may be related to the shedding and eruption of teeth. The differences between childhood and adult types of ameloblastomas are highlighted.


Metastatic tumors to the jaws and oral cavity.

Observations of the incidence of MT from distant organs and tissues to the maxillofacial region are presented on the basis of 13 cases (3.2% of the total number of patients with malignant tumors). Metastatic carcinomas are most frequently found in the mandible (61.5%). The primary locus is usually the breast, kidney, bronchus, or thyroid gland (61.5%), the diagnosis of metastasis aided in localization of the primary tumor. Successful results of radical treatment were obtained in only two cases; they survived for three and 11 years. The other 11 patients died within two months to a year. The function of maxillofacial surgeons in discovering primary and metastatic tumors of the jaws and face is emphasized.


Thrombophlebitis after intravenous use of anesthesia and sedation: its incidence and natural history.

A number of technical and clinical conditions reportedly associated with diazepam-related thrombophlebitis were investigated. Diazepam alone and in combination with fentanyl and methohexital was administered intravenously to 519 healthy, predominantly young adult patients undergoing routine oral surgery for removal of third molars. Indirect evidence is provided to show that two slightly different vasculopathies are involved: thrombophlebitis, in which pain and induration are both present but in which there is a slight delay in the time of inception of the condition; and phlebothrombosis, in which the reaction is almost immediate but pain is not significant and induration of the vein is the predominant feature. The overall incidence was 2.3% for thrombophlebitis and 9.8% for phlebothrombosis. There were four significant variables associated with phlebothrombosis: use of tobacco, use of oral contraceptives, multiple injections of diazepam, and pain during injection. The only significant variable associated with thrombophlebitis was the site of injection.


Necrotizing sialometaplasia after bronchoscopy.

Since the introduction of necrotizing sialometaplasia into the literature as a distinct pathologic entity in 1975, there have been several reports containing microscopic findings consistent with the disease primarily of the hard palate, but also of the soft palate, major salivary glands, retromolar pad of the mandible, and mucous glands of the nasal cavity. Localized ischemia appears to be a common link. All reported lesions heal with or without surgical intervention. Generous incisional biopsy specimens should be taken and aggressive surgery should be avoided.


Acinic cell carcinoma of the palate: report of case and review of the literature.

The literature regarding acinic cell carcinoma is reviewed, and a case of such a tumor located in the hard palate is described. Metastasis to lymph nodes in the neck occurred bilaterally, with early recurrence by direct infiltration.


Chondrosarcoma of the maxilla: report of case.

Chondrosarcomas of the jaws are rare tumors; an additional case in the maxilla is described. The literature that discusses the pathogenesis of the tumor, its biological behavior, and the preferred treatment is reviewed. The histologic differentiation between chondrosarcoma and benign cartilagenous tumors is discussed.


Phenomenon of mucous retention in the incisive canal.

Mucous glands are rarely found in the anterior palate but may be observed in the incisive canal. A case history is presented of a lesion that resembled a nasopalatine cyst both clinically and radiographically but which was in fact an intra-bony extravasation phenomenon.


Spontaneous-ventilation general anesthesia for outpatients using enflurane.

We have described our technique for general anesthesia for outpatients using a mixture of nitrous oxide, oxygen, and enflurane with spontaneous ventilation through a Bain anesthetic circuit. In our experience, surgical excision of impacted teeth, multiple extractions and alveoloplasty, enucleation of simple cysts, excision of benign tumors, and other similar operations have been done efficiently with these anesthetic techniques. More than 500 such cases have been managed without significant complication. The concepts of selection and preparation of patients, airway security and protection during surgery performed in the upper airway on an unconscious patient who is breathing spontaneously, continuous monitoring of vital functions, and rapid induction and recovery all combine to make this technique consistent with standards for excellence in anesthesia.


A follow-up report of long-term survivors of childhood acute lymphoblastic or undifferentiated leukemia. A report for Childrens Cancer Study Group.

From an original group of 229 patients with acute lymphoblastic leukemia or acute undifferentiated leukemia diagnosed in 1963 and 1964, 15 patients who achieved greater than 2 1/2 years continued complete remission were assigned either to continue with maintenance therapy or to discontinue therapy. Five of the 15 patients have died after surviving from six to ten years from the time of diagnosis. Of the remaining ten patients, all are alive and free of disease for more than 14 years from diagnosis. No relapses or deaths have occurred in patients off therapy for greater than five years. In this small series of patients, there was no difference in survival in the continued or discontinued therapy groups. No overt adverse effects of therapy have been seen in the ten surviving patients. These encouraging data need to be extended and confirmed, utilizing patients treated with the more sophisticated therapeutic approaches employed in modern protocols for ALL/AUL. Identification of adverse effects of therapy will require appropriate and careful surveillance of large groups of successfully treated patients.


A new reinforced intracoronal composite resin splint. Clinical results after 1 year.

An intracoronal technique for semipermanent splinting of mobile or migrating teeth is described and clinically evaluated. Circumferential grooves of 1 to 1.5 mm depth were cut into the enamel in the occlusal third of the teeth to be splinted. The teeth were splinted by placing a polyester ligature in two or more figure-8 loops along the grooves, and sealing the grooves and interproximal contact areas with an acid-etch composite resin system. A total of 51 splints involving 183 teeth and 132 interproximal contact areas were placed in 34 patients. One year after insertion, 46 splints were found intact. Five splints presented with one fractured interdental element, each. Average mobility of the splinted teeth was 51% below the preoperative level. Splinting improved the masticatory comfort. The esthetic results were satisfactory.


Measurement of the millimeter markings of periodontal probes.

All periodontal probes used by five periodontists were collected and their millimeter markings were measured for accuracy. It was found that most probes were not precise, especially those manufactured by Hu-Friedy more than 3 years ago. However, new probes manufactured by Hu-Friedy were shown to be more accurate. It is recommended ttht dentists use periodontal probes with accurate and consistent markings.


Assessment of tissue conditioning materials for functional impressions.

The validity of two types of tissue conditioning materials was studied and compared with that of two commonly used impression materials. The effect of three important factors on the accuracy of the impressions was observed. These factors were thickness of the impression material, time of compression of the impression, and the time interval before pouring the impression. A chrome-cobalt master cast was specially designed and 500 impressions were made and poured, resulting in 900 casts. Conclusions reached from this investigation were that: 1. Visco-Gel and Coe-Comfort tissue conditioning materials can be used as impression materials. 2. The dimensional accuracy of Visco-Gel is better than that of the Coe-Comfort impressions. 3. There is no significant difference between using a tray with a space of 1.5 mm or 3.0 mm for the impression material. 4. The less bulky the impression, the less time is required for compression with fewer inaccuracies. 5. It is preferable to pour the cast in the impression immediately or within 2 hours. 6. Both kinds of materials tested can be used as duplicating materials under certain conditions.


Replicability of chinpoint-guidance and anterior programmer for recording centric relation.

The chinpoint-guidance technique, using an anterior programmer, as performed in this study, seems to be a replicable method of locating centric relation. Sequential registration of centric relation was repeatable in 60% of the patients studied. The average variability found in 40% of the patients of this study was about +/- 0.20 mm at the level of the condyles.


Prosthetic treatment for electrical burns to the oral cavity.

A procedure was presented to provide an esthetic result in the treatment of electrical burns to the mouth. A removable prosthesis controls the degree of scarring, contracture, and deformity that often occurs from the surgical repair of these burns.


An evaluation of the cure of acrylic resin by three methods.

An investigation was designed and carried out to compare methyl acrylic resin processed by three methods--boiling, in the heat platen press, and a 9 hour, 75 degrees C cure. The material was cured in certain thicknesses in the heat platen press and by boiling without porosity. All samples cured for 9 hours at 75 degrees C had no porosity. The value of the heat platen press as a time-saving device and its applications in a maxillofacial laboratory were discussed.


The validity of temporomandibular joint radiographs using the head positioner.

1. TMJ radiographs made using the head positioner provide a valuable adjunct to diagnosis and treatment planning for patients with MPD syndrome. 2. Where extensive restorative procedures are anticipated, TMJ radiographs can be useful before embarking on a treatment plan and in documenting the postoperative results. 3. Bilateral condylar symmetry is a reasonable objective of extensive restorative dentistry. 4. Radiographic retrusion is more frequently accompanied by signs and symptoms than bilateral condylar symmetry and protrusion.


Tissue culture and histologic study of a new elastomer.

A new silicone material, Silastic MDX 4-4210, was tested by tissue culture and tissue implantation to compare host reaction with known toxic and nontoxic materials. It was not found to be toxic to a monolayer of HEL cells, and it evoked a minimal foreign body reaction when implanted in albino rats. Further clinical studies are indicated to evaluate host reaction of this silicone in long-term contact with human mucous membrane and skin tissue.