Morphodifferentiation and histodifferentiation of the dental hard tissues in compound odontoma: a study of undemineralized material. Dental hard tissues and mineralization at the enamel surface or in the ameloblastic epithelium were studied in 10 odontomas using undemineralized material. All the specimens showed a high degree of histo- and morphodifferentiation. Dentin formed the bulk of the tumors. Much of the enamel was prismatic and apparently normal and in almost every specimen were present enamel tufts and spindles. At greater magnification it could be seen that the prisms had a very irregular orientation. Cementum was mostly acellular. Calcified material formed focally in the intercellular portion of the enamel epithelium: this material showed a concentric layers arrangement.


Acid production by Actinomyces viscosus of root surface caries and non-caries origin during glycogen synthesis and degradation at different pH levels. Actinomyces viscosus strains, freshly isolated from root surface caries lesions and intact root surfaces, were studied for their glycogen synthetic and degradative activities at pH 4.5, 5.0, and 7.0 in a pH-stat. At all three pH levels, root caries origin of A. viscosus synthesized up to three times as much glycogen compared to non-root caries origin. Since root caries origin of A. viscosus strains initially synthesized large amounts of glycogen, a longer period of time was required to deplete this polymer, resulting in an extended period of acid production, even at pH 4.5 and pH 5.0. This study suggests that the ability of A. viscosus of root caries origin to synthesize large quantities of glycogen and subsequently degrade this stored polymer slowly with acid production, at acidic pH levels, may play an important role in the root caries process.


Variants of the adenomatoid odontogenic tumor with a note on tumor origin. Three rare variants of the adenomatoid odontogenic tumor (AOT) are described. A follicular AOT associated with an impacted and displaced 28, an extra-follicular variant mimicking a radicular cyst around the apex of 23 and a peripheral (epulis-like) variant exhibiting a periodontal bone defect palatal to 21. On reappraisal of the origin and pathogenesis of the AOT, it would seem that this tumor or hamartomatous lesion is derived from odontogenic epithelium of the dental lamina complex or its remnants.


Occurrence of oral leukoplakia and lichen planus in diabetes mellitus. The occurrence of oral leukoplakia and lichen planus in 1600 patients with diabetes mellitus (815 type 1: insulin-dependent, 761 type 2: non-insulin-dependent)-under care at the International Medicine Department-was studied. Precancerous lesions and conditions were diagnosed and grouped according to internationally accepted criteria. The prevalence of oral leukoplakia in diabetic patients was 6.2%, as compared to 2.2% in the healthy controls, that of oral lichen was 1.0% in the test-, and 0.0% in the control group. Leukoplakia and lichen both showed the highest occurrence in the second year of established diabetes, and their prevalence was higher among insulin-treated diabetics. Smokers were more often affected, by both kind of lesions, oral lichen showed a more frequent association with candidiasis. The prevalence of oral leukoplakia and lichen in diabetes mellitus patients was higher, than average ratios in population samples from the same country.


Comparison between new saliva stimulants in patients with dry mouth: a placebo-controlled double-blind crossover study. Two new saliva stimulants: V6 and a mucin containing chewing gum were tested in this placebo-controlled double-blind crossover study. Forty-three patients (mean age 63 yr) complaining of dry mouth participated. The products were administered in a randomized order, and used for 2 wk each. The effect was evaluated by interviews and by determining changes in stimulated and unstimulated saliva flow rates. A positive effect was reported by 64%, 44%, and 26% of the patients using the mucin chewing gum, V6, and the placebo, respectively. More than 2/3 of the patients found the mucin chewing gum efficient at various times and situations. Sixty-one percent of the patients preferred the mucin chewing gum, 21% V6, and 5% the placebo product. Fifty percent of the patients had an increase in unstimulated salivary secretion rate from all products after 14 days regular use indicating a long-term effect.


Purine modulation of prostaglandin F2 alpha (PGF2 alpha)-induced premature luteolysis in vivo in nonpregnant sheep. In two separate experiments, control and PGF2 alpha-treated unilaterally ovariectomized ewes received vehicle or adenosine every four hours through an exteriorized catheter installed either to parafuse the ovarian vascular pedicle of the remaining ovary containing a corpus luteum (CL) or to infuse intrauterine ipsilateral to the remaining ovary with the CL. Infusions were given every four hours from day 7 through day 22 postestrus or until ewes returned to estrus. Chronic infusion of vehicle intrauterine or parafusion of the ovarian vascular pedicle with vehicle in PGF2 alpha-treated ewes shortened the interestrous interval compared to controls (P less than 0.05). However, chronic parafusion of the ovarian vascular pedicle with adenosine in PGF2 alpha-treated ewes prevented a PGF2 alpha-induced premature luteolysis (P less than 0.05) but not when adenosine was infused chronically intrauterine (P greater than 0.05). It is concluded that adenosine can block a PGF2 alpha-induced premature luteolysis in vivo and may have roles in regulation of luteal secretion of progesterone but it is probably not the embryonic antiluteolysin of early pregnancy in ewes.


Inhibition of thrombin-induced platelet activation by dioctanoylglycerol pretreatment is not correlated with the 47 kDa protein phosphorylation. The effect of platelet pretreatment with moderate amounts of 1,2-dioctanoylglycerol on subsequent thrombin-induced activation and its correlation with the degree of protein phosphorylation is studied. Protein kinase C preactivation (treatment with 1 microM dioctanoylglycerol for 20 min) significantly reduces thrombin-promoted platelet aggregation, cytosolic calcium-rise, ATP-secretion and, albeit to a lesser extent, protein phosphorylation. Exposure of platelets to dioctanoylglycerol brings about a transient phosphorylation of a 47 kDa protein and a slight but more persistent phosphorylation of proteins of approximate molecular mass 26 and 68 kDa. It is hypothesized that the latter phosphoproteins are responsible for the inhibition of the thrombin-promoted platelet activation. Agonist-evoked aggregation is more affected by a long (20 min) rather than a short (1 min) pretreatment with dioctanoylglycerol, showing no correlation with the phosphorylation of the major substrates of protein kinase C.


Comparison of second messenger formation in human keratinocytes following stimulation with epidermal growth factor and bradykinin. We have examined the ability of recombinant human epidermal growth factor (EGF) and bradykinin (BK) to stimulate formation of inositol polyphosphates and sn-1,2-diacylglycerol (DAG), and mobilize intracellular Ca2+ ([Ca2+]i) in adult human keratinocytes (KC). Inositol polyphosphates were resolved by high performance liquid chromatography coupled with flow detector spectroscopy. Free intracellular calcium was quantitated using digital ratio imaging fluorescence microscopy of fura-2 loaded KC. The mass amount of DAG was quantitated using the DAG kinase reaction. When comparing maximal doses of BK (0.1 microM) and EGF (200 ng/ml), BK stimulated larger increases in all second messengers measured. The majority of cells responded rapidly to BK with global increases in [Ca2+]i. Cells responding to EGF were fewer in number and slower to respond with the Ca2+ signal being less pronounced. Treatment of cells with pertussis toxin (PTX) for 24 h significantly attenuated the BK-stimulated inositol polyphosphate formation and [Ca2+]i while the EGF response remained unaffected in both parameters. BK (10(-9) to 10(-6) M) did not stimulate DNA synthesis in KC as measured by [3H]-thymidine incorporation when cultures were treated for 5 days. These results demonstrate that the coupling and biochemical signals produced by stimulation of BK and EGF receptors in human KC are different and suggests that stimulation of second messenger formation from inositol lipid hydrolysis may not be an absolute requirement for the initiation of cell proliferation.


Protein kinases associated with isolated mitotic spindles from mammalian cells: identification of a casein kinase II-like enzyme. Mitotic spindles isolated from prometaphase-arrested mammalian cells contain associated protein kinases that are extracted by high salt treatment. Their fractionation by ion-exchange chromatography reveals three major peaks of protein kinase activity that phosphorylate brain microtubule-associated proteins and differ in their substrate specificity. One of them has been identified as a casein kinaseII-like enzyme. A mitotic spindle-associated 325 kDa protein related to brain MAP1B is a major substrate for this casein kinase II-like enzyme. Another mitotic spindle protein kinase has been tentatively identified as a proline-directed protein kinase.


Protein kinase C phosphorylates both serine and threonine residues of the mRNA cap binding protein eIF-4E. Several lines of evidence indicate that phosphorylation of the 25 kDa mRNA cap binding protein (eIF-4E) stimulates the efficiency of translational initiation. While the protein kinases which catalyze this reaction in intact cells have not been completely identified, evidence suggests that protein kinase C phosphorylates serine residues of eIF-4E in intact cells. In this study we demonstrate that protein kinase C also phosphorylates threonine residues of recombinant human eIF-4E in vitro. Phosphorylation of threonine and serine was observed over a range of eIF-4E and salt concentrations. However, relatively low levels of phosphorylation were seen even under optimal conditions. Similar results were observed with native eIF-4E purified from human erythrocytes. These findings demonstrate that protein kinase C can phosphorylate both serine and threonine residues of eIF-4E in vitro, but suggest that protein kinase C may not be the primary enzyme that phosphorylates eIF-4E in vivo.


Rehabilitation with calvarial bone grafts and osseointegrated implants after partial maxillary resection: a clinical report. Osseointegrated implants can be positioned on the nondefect side of a midline maxillary resection if there is sufficient residual bone. Axial loading of the implants is difficult because the axis of rotation for an obturator prosthesis is located along the palatal margin of the defect. Rotation of the prosthesis due to a class I lever will encourage stresses within the implants and the bone surrounding the implants on the nondefect side, and this may be detrimental. Placement of implants within the defect will prevent rotation of the prosthesis and encourage axial loading of the implants.


Fracture resistance of composite and amalgam cores retained by pins coated with new adhesive resins. This study determined the effects of coating pins with either Panavia EX or with 4-META (Cover-Up) materials on the fracture resistance of pin-retained amalgam and composite cores. Gold-plated stainless steel (TMS) and titanium (Filpin) self-threading pins were used. Findings of this study corroborated the findings of several other studies that the use of pins reduces the fracture resistance of restorations. However, coating the pins with adhesion promoters such as Panavia EX and 4-META materials has been found to be effective in improving the fracture resistance. Cross-preference was observed between TMS and Filpin pins; that is, Panavia material coating was more effective with TMS pins, while 4-META was more effective with Filpin pins.


Clinical management of abutments with intracoronal attachments. A method of preparing teeth to accommodate intracoronal attachments is presented. The resulting prosthesis incorporates a fixed partial denture with physiologically contoured crowns and a removable partial denture with a precisely determined path of insertion. These techniques stress the importance of surveyed diagnostic casts and coordinated tooth preparations for artificial crowns to facilitate treating complex cases.


Effect of dentinal bonded resin post-core preparations on resistance to vertical root fracture. An in vitro study was conducted to compare the resistance to failure of two restorative protocols for endodontically treated teeth. Half of 24 specimens received cemented cast post-core restorations and the other half were restored with dentin-bonded composite resin using the ferric oxalate, NTG-GMA, and the PMDM system developed by Bowen. The dentin-bonded resin post-core restorations provided significantly less resistance to failure than the cemented custom cast post-core. The dentin-bonded resin post-core fractured in every instance before the root fractured. A greater force was required to cause failure of the resin post as the cross-sectional area of the post increased.


A comparative study of ceramic crown margins constructed using different techniques. This study compares three variations of the direct lift-off technique utilizing porcelain materials with thermoplastic, modeling liquid, and visible light-cured resin carriers. Three commercially available materials were evaluated. Vita, Ducera, and Dentsply Spectrum. Measurements were made of the width of the marginal gap for three sites at each of four stages: (1) after the shoulder firing, (2) after the body-incisal firing, (3) after the glaze firing, and (4) after a correction firing. All techniques produced marginal gaps in the clinically acceptable range. Use of the Vita thermoplastic carrier porcelain material resulted in the smallest marginal gap at all but the body-incisal stage. Crowns done with the Ducera and Spectrum materials had statistically similar marginal gaps at all but the glaze stage, where the Ducera material crowns demonstrated the largest marginal gaps.


Composite resin color change after vital tooth bleaching. Color change of composite resin was determined with the Minolta Chroma meter (CR-100) after four sessions of vital bleaching. Specimens of selected composite resin materials were subjected to vital bleaching (37% H3PO4/1 minute, then 30% H2O2/infrared light/30 minutes.) Specimens were stored in water between bleaching. Control specimens were used to determine the effects of water storage alone. Initial L*a*b* color readings were made on 24-hour hydrated specimens. Final L*a*b* readings were made on 24-hour hydrated specimens. Calculations were made for the delta E values for each specimen. Mean delta E values and standard deviations were obtained for each material. Two-way ANOVA and Newman-Keuls analyses showed significant (alpha = 0.05) color change for most bleached materials. Additionally, some materials had delta E values greater than 3. These were visibly lighter compared to their controls. Vital bleaching produced color change in most composites as measured with the Chroma meter. This technique may be used to lighten dark-colored or stained composite resin restorations.


Effects of cement, cement space, marginal design, seating aid materials, and seating force on crown cementation. An evaluation of the effects of a die spacer, the seating force, the marginal design, seating aid materials, and the cement type during cementation was conducted. Two stainless steel dies were used: one with a 1 mm shoulder and the other with a shoulder and a 65-degree bevel. Ten stone dies were produced from each metal die and half were painted with four layers of die spacer. The crowns were waxed on the dies and cast in a nonprecious alloy, and the seating of crowns was measured with a micrometer before and after cementation. Comparisons were made between zinc phosphate and glass ionomer cements under two seating forces of 5 and 30 lb using an orangewood stick or E-Z-bite seating aid. ANOVA and the Newman-Keuls test revealed that the use of a die spacer, a heavier force of 30 lb, and glass ionomer cement significantly improved crown seating. The beveled preparation led to superior crown seating when the heavier force or glass ionomer cement was used. The orangewood stick and bite device had a similar effect on crown seating.


Effects of 'resin-compatible' cavity varnishes on composite resin microhardness. Although the use of cavity varnishes with composite resins has traditionally been discouraged, several "resin-compatible" varnishes are currently available. This in vitro study evaluated the effects of resin-compatible cavity varnishes on a hybrid composite resin. The results of the study indicate that these varnishes soften the composite resin in contact with varnished dentin.


Viscosity of monophase addition silicones as a function of shear rate. The viscosity of monophase addition silicone impression materials was measured as a function of shear rate. The setting of mixed catalyst and base was prevented by addition of a small amount of phenyl propiolic acid. All products showed a 6- to 10-fold decrease in viscosity with an increasing shear rate (shear thinning). The addition of phenyl propiolic acid had little or no effect on the viscosity of three materials. However, when added to the catalyst or base only of two products, it increased their viscosity and exaggerated the shear thinning effect.


A secondary lingual casting for removable partial dentures. This article describes a technique for constructing a nickel chromium alloy lingual casting that reinforces a removable partial denture against heavy anterior occlusion. The metal can be cast into a thin secondary casting, and it is easily etched and bonded to the resin anterior teeth and associated base. This type of lingual casting has the potential to provide a simple and effective solution to the problem of repeated fracture or displacement of anterior teeth in many restorations.


Mandibular complete denture impressions with fluid wax or polysulfide rubber: a comparative study. Some authors have stated that wax cannot be used to make impressions for complete dentures, while others have found that wax has some advantages over elastomeric impression materials. The purpose of this study was to compare mandibular impressions made with a fluid wax to those made with light-body polysulfide rubber. Fifteen maxillary and mandibular complete dentures were made using fluid wax as a final impression material. For comparison, 15 maxillary and mandibular complete dentures were made using light-body polysulfide rubber. The number of adjustments required over 1 year was recorded. No statistical difference in adjustments was noted between the two groups.


The position of the neutral zone in relation to the alveolar ridge. Included in this study are 21 edentulous patients. They were classified according to their period of edentulousness into two groups. One group was edentulous from 1/2 to 2 years. The other group was edentulous for more than 2 years. The neutral zone (NZ) was located for each patient by using record bases, and an impression compound as the occlusion rim. A 30-gauge stainless steel wire was adapted along the center of the alveolar ridge on the final cast. A 24-gauge stainless steel wire was adapted and stabilized over the center of each occlusion rim. An occlusal view radiograph was obtained of each recording base and its cast. Each film was placed in a viewing box and the relationship between the images of the two wires in the buccolingual direction was studied in the anterior, premolar, and molar regions on the left and right sides. Where the two images coincided a zero score was given. In the case of buccal location a plus scores was given, and where there was a lingual location of the (NZ), a minus score was given. All measures were taken in millimeters. Statistical analysis was performed between the two groups. The longer the period of edentulousness, the more buccally/lingually located was the NZ.


Denture tooth selection: an analysis of the natural maxillary central incisor compared to the length and width of the face: Part II. This is the second part of a project conducted by the Removable Prosthodontic Faculty to compare the length and width of the maxillary central incisor with the length and width of the face. In this article, gender of the students was the main consideration. Three hundred fifty men and 138 women students participated in the project.


Laboratory wear investigation of resin posterior denture teeth. This investigation compared the wear resistance of three "improved" resin posterior denture tooth formulations with two conventional products on a mechanical toothbrush abrasion machine. The ability of the teeth to resist this type of abrasion was evaluated by determination of the weight loss during 339 hours of brushing with firm nylon bristle toothbrushes. All brands exhibited negligible loss, with the conventional brands performing better than the "improved" formulations.


Effect of repair surface design, repair material, and processing method on the transverse strength of repaired acrylic denture resin. The transverse strengths of blocks of denture base acrylic resin repaired with autopolymerizing monomer and polymer and autopolymerizing monomer and heat-cured polymer were measured with a three-point bending test. Three repair joints were studied: butt, round, and 45-degree bevel. Three processing methods were used: bench cure, hydroflask with hot water for 10 minutes, and hydroflask with hot water for 30 minutes. The strengths of repairs made with round and 45-degree bevel joint designs were similar and significantly greater than those with a butt joint design. The strengths of repairs processed in a hydroflask for 10 minutes and 30 minutes were similar and significantly greater than those cured on the bench top. There was no difference in the strength of repairs made with autopolymerizing monomer and polymer and autopolymerizing monomer and heat-cured polymer.


The knife-edge tendency in mandibular residual ridges in women. To investigate the bone resorption pattern of the residual alveolar bone, the morphologic change that occurred in mandibles was analyzed with standardized lateral cephalographs of 30 edentulous patients (15 women and 15 men). The longitudinal morphologic changes were measured at the sagittal sections of the mandibular bony contour at the symphysis area on superimposed cephalographic tracings. To quantify the morphologic change, a knife-edge index (KEI) was developed as the area change divided by the height change. Geometrically, the higher value of KEI represents the greater tendency to become a narrow residual ridge. The KEI values were statistically higher in the women than in the men (p less than 0.002). In addition, the value of KEI seems to correlate with osteopenic change at the center point of the body of the second vertebra (p less than 0.01). The continuous bone resorption activity in the edentulous mandible of women seems to be emphasized at the labial and lingual surfaces of the residual alveolar bone, resulting in a knife-edge type of residual ridge.


An analysis of the effect of mandibular length on residual ridge loss in the edentulous patient. The relationship of mandibular length to residual ridge loss was studied in 22 edentulous patients. Tracings made from cephalometric films taken at initial insertion of complete dentures and at 20 years after placement were measured. Mandibular length was determined to have no statistical relationship to the reduction in residual ridge height in either the maxillae or the mandible. In addition, alveolar bone loss in the one jaw had no relationship to the amount of loss in the other jaw.


A surgical guide for implant placement.

A surgical guide for implant placement. Mounted diagnostic casts aid in determining whether sufficient space exists for a fixed cantilevered implant prosthesis. These casts are also used to construct a surgical guide. Such a technique is described.


An appliance to correct mandibular deviation in a dentulous patient with a discontinuity defect. The mandibular discontinuity defect is one of the most difficult problems in prosthetic dentistry. This article describes an appliance that has been used successfully in reducing or correcting the deviation in dentate patients who have experienced mandibular resection. It consists of a prefabricated integrated tube and plunger that are hinged to clear acrylic resin maxillary and mandibular appliances.


Occlusal force after partial mandibular resection. Surgical resection of a segment or loss of mandibular continuity can adversely affect most of the structures essential for maximum occlusal force. Five subjects who had partial mandibular resections for treatment of squamous cell carcinoma were studied. Occlusal force was recorded before and after cancer treatment and following prosthetic rehabilitation. A gnathodynamometer was used to record anterior occlusal force. Five edentulous and five dentate cancer-free subjects matched for age were studied to establish comparable normative data. The null hypothesis that partial mandibular resection would not affect maximum occlusal force was rejected (p = 0.0101). Mandibular resection did alter maximum occlusal force. The impact of the decrease in maximum occlusal force on masticatory function is yet to be determined.


Tenderness on palpation and occlusal abnormalities in temporomandibular dysfunction. Tenderness on palpation indicates objective painful symptoms. This study investigated the tenderness of the temporomandibular joint, muscles and their relation to occlusion in patients with temporomandibular dysfunction. Two hundred ten patients were examined; 96% had tenderness and 80% of cases of tenderness were diagnosed as occlusally related. The average number of tender areas was 5.4 per patient, despite the contribution of occlusion. Tenderness was observed most frequently in the lateral pterygoid muscle, followed by the insertion of temporal muscle. There was no correlation of temporomandibular joint tenderness to muscle tenderness, while tenderness of certain muscles to each other was correlated. Differences were related to the state of occlusion in the number of tender areas, to the ratio to tenderness of elevator muscles to horizontally acting muscles, and to the frequency of unilateral tenderness. The association of muscle tenderness and occlusion was suggested.


The effect of age on condylar asymmetry in patients with craniomandibular disorders of arthrogenous origin. A group of patients with a craniomandibular disorder of arthrogenous origin demonstrated an age-related variation of condylar asymmetry with age. This may reflect a greater depletion of the mesenchymal cell layer, which is responsible for adaptation of the articular surface as age increases. This would then result in greater deterioration of the articular surfaces and a consequent decrease in condylar asymmetry.


Wet versus dry enamel ablation by Er:YAG laser. The purpose of this study was to observe tooth structure and pulpal temperature changes in extracted human teeth subjected to a pulsed Er:YAG (2.94 microns) laser. Two teeth were irradiated while dry and three teeth while moistened by a fine water mist. When the dry teeth were irradiated, there was minimal enamel ablation. SEM of the resulting surface showed rounded fragments of enamel rods, enamel melting, cracks, and smooth-edged voids. Intrapulpal temperature measured by thermal sensor rose more than 27 degrees C. When the laser application on the teeth was pulsed with a constant fine water mist, enamel and dentin were efficiently ablated. SEM of the resulting surfaces showed fissures and conical craters with sharp enamel projections remaining. Intrapulpal temperatures rose an average of 4 degrees C. These results indicate that pulsed Er:YAG (2.94 microns) used with a water mist removes enamel and dentin without producing significant pulpal temperature changes.


A scanning electron microscopy study of the effect of bleaching agents on enamel: a preliminary report. The effect of bleaching agents on the enamel surface was examined by scanning electron microscopy. The comparison of treated to untreated enamel revealed that the treated surface had increased surface change and porosity after the equivalent of 30 hours of exposure to the bleaching agent. The degree of alteration of enamel surface was not uniform and was influenced by cleanliness (oral hygiene) of the treated teeth and apparent variation in calcification. The enamel surface developed varying degrees of surface porosity and alteration.


Effects of temporary cementation on permanent cement retention to composite resin cores. This in vitro study compared the effects on retention of base metal cylindrical retainers placed on composite resin cores when pretreated with eugenol and noneugenol temporary cements. Sixty composite cores and base metal cylindrical retainers were tested. The cores were pretreated with eugenol and noneugenol temporary cements before eventual cementation with resin and zinc phosphate cements. Cemented core retention was measured by application of a compressive force to the cores in an Instron machine. Differences were found between the two permanent cements. Pretreatment with eugenol cement reduced retainer retention with resin cements, but had no effect with zinc phosphate cement. Pretreatment with noneugenol cement did not reduce retainer retention.


A review of the strength properties of dental ceramics. New ceramic materials for restorative dentistry have been developed and introduced in recent years. This article reviews advantages and disadvantages of dental ceramics, concentrating on strength properties. Included are factors affecting the strength of dental ceramic materials and the most common mechanisms for increasing the strength of dental ceramics. The properties of presently available materials such as dispersion-strengthened ceramics, cast ceramics, and foil-reinforced materials are discussed. Current research efforts to improve the fracture resistance of ceramic restorative materials are reviewed. A description of methods to evaluate the strength of ceramics is included, as a caution concerning the interpretation of strength data reported in the literature.


Long-term outcomes for remedial students. A recent survey of dental schools concluded that current efforts toward remediation are inadequate. A remedial waxing course providing recognition training before production attempts, emphasis on formative self- and peer-evaluation of projects, and application of a highly structured format for ensuring relevant practice had been developed and favorably evaluated previously. The current report follows the progress of two differently trained remedial groups and the remainder of the class in two courses following remediation. On the five subsequent practical examinations analyzed, the experimental group continued to perform at the class mean. On one practical examination, the experimental group significantly outperformed the traditional group (p less than 0.02). For three of the five examinations, the traditional group was significantly outperformed by the class. One of the six students in the experimental group required additional remediation. Of the seven in the traditionally remediated group, one left school and four required additional remediation. An apparent changing remediation pattern in the preclinical training period is described and possible reasons for the change are explored.


A simplified intraoral surveying device. This article describes an easily made and used intraoral surveying device that can aid the dentist in transferring needed preparation information from the diagnostic cast. This device also allows checking of the preparations as they are progressing. The device consists of a Proxabrush handle and a drafting lead.


Accuracy and dimensional stability of a combined hydrocolloid impression system. The accuracy of a combined hydrocolloid impression system was studied as a function of time of pour. There was little change in dimension between posts for all time intervals studied. No statistically significant differences were noted among the observation periods until 3 hours. The results indicate that for the impression system studied, a 3-hour pouring time can be used for transport to a commercial dental laboratory, provided the impressions are stored in 100% relative humidity. The hydrocolloid impression system tested resulted in a stone cast of slightly deviating dimensions compared with the master model. Therefore laboratory procedures should compensate for cement thickness, taking into account the minimal changes in dimensions of the die.


The dimensional accuracy of rectangular acrylic resin specimens cured by three denture base processing methods. The dimensional accuracy of rectangular acrylic resin specimens was examined when they were processed by three methods: a conventional method, the SR-Ivocap system, and a microwave curing method. The dimensional accuracy was evaluated by the change of the distance vector V, which is calculated by means of measurements of the distances between fixed points on specimens. The specimen cured by the SR-Ivocap system exhibited less dimensional change (p less than 0.05) than those cured by the conventional and the microwave curing methods. The SR-Ivocap system might produce a more accurate denture base than the conventional and the microwave curing methods.


Microwave processing of cleft palate orthopedic expansion devices. This article describes a method for making a palatal expansion device for use in conjunction with orthopedic repositioning of the premaxilla in patients with bilateral cleft palate. The technique of constructing the devices involves the microwave processing of a permanent soft liner and a heat-cured acrylic resin in a single-stage curing cycle. The resultant expansion device has the advantages of a soft liner for retention in the nasal cavity and an oral cavity surface that is smooth and closely adapted to the tissues. A paper cover is used during the flasking process, which allows packing of materials without displacement into undesirable locations.


Equipping a dental laboratory: fabricating a pressure pot. A pressure pot has many applications in dentistry. This article describes a simple method of converting an everyday kitchen pressure cooker into one that can be used in dentistry. The technique is simple, and the components needed are readily available at a local hardware or department store. The advantage of this pressure pot is that it can be made for one third to one half the cost of purchasing one from a manufacturer.


Simplifying the altered cast impression technique for distal-extension removable partial dentures. This technique allows construction of a detachable custom tray by the dental laboratory before the distal extension RPD framework is returned to the dentist. This permits a framework try-in with unencumbered physiologic relief, rapid attachment of the custom tray, subsequent impression making, and possibly jaw relation records all in one patient visit.


An alternative immediate complete denture impression technique. An alternative immediate denture impression technique for extremely mobile teeth, utilizing amalgam condensers, has been presented. The apically applied pressure on the mobile teeth minimizes the risk of accidental tooth extraction during impression removal.


Technique to diminish discomfort from the palatal injection. A new technique for diminishing the discomfort of a palatal injection has been described. The technique utilizes a cotton pellet saturated with dichlorodifluoromethane spray held in contact with the tissue 5 seconds to freeze a small portion of the surface tissue. The injection needle then penetrates the frozen tissue with little discomfort to the patient.


Alloplastic cranial implants made from computed tomographic scan-generated casts. The complexity of cranioplasty increases with increased defect size. It is difficult to produce a symmetric, accurate implant presurgically or at the time of surgery when the defect is greater than 50 cm2. The procedure is also more difficult to perform when the defect is located in the temporal, infratemporal, or frontal areas. A new procedure generates a three-dimensional cast of the skull through computed tomography and computer-aided design reformation. This article describes the process of model generation and the production of a preprocessed cranial implant. To date, six cranial implants have been made with this technique. The whole head models are accurate and help the neurosurgeon-prosthodontist team in the creation of a symmetric, anatomically correct restoration. It is the technique of choice for large implants or where the cranial bones are thin. It is not necessary to augment or alter the implant during surgery. The technique reduces surgical time, and postsurgical complications have been minimal.


Sleep apnea prosthesis for dentate patients. This article describes clinical and laboratory techniques for the fabrication of a sleep apnea prosthesis for a dentate patient. The treatment objective is to posture the mandible at an increased vertical and protrusive position to diminish or eliminate the collapse of the base of tongue into the oropharynx. During fabrication of the prosthesis, cephalograms are used to evaluate spatial change between the base of the tongue and the posterior pharyngeal wall.


The design of a two-part acid-etched resin-bonded fixed partial denture. A new framework design is presented for resin-bonded, acid-etched, fixed partial dentures. This innovative design divided the restoration into two parts, each with a separate path of insertion. The preparation of abutment teeth required minimal reduction and the pontic could not be displaced during function. Thirty-five patients with missing posterior teeth have been treated with this imaginative approach and after approximately 2 years, there have been no debonding failures.


Clinical evaluation of the gingiva around single-crystal sapphire endosseous implant after experimental ligature-induced plaque accumulation in monkeys. This study was performed to evaluate clinical changes of the gingiva with plaque accumulation around the single-crystal sapphire implant. Four implants were inserted into mandibular and maxillary edentulous regions, and the superstructure was inserted 1 month after insertion of the implants in each of nine monkeys. Plaque control was maintained for 3 months after insertion to set up the baseline. Plaque was allowed to accumulate on one side by placing the ligature around the implant and natural teeth without any plaque control, and on the other side plaque control was continued for 9 months. Both the implant and natural teeth on the ligature side showed a significant increase in the clinical parameters of plaque index, gingival index, and probing depth. No significant difference was obtained between the implant and natural teeth. These findings indicate that plaque control is of great importance for maintaining the health of peri-implant gingiva.


Radiotherapeutic management of an orocutaneous defect with a balloon-retaining stent. Maxillary resection defects have traditionally been technically difficult to treat with conventional radiation therapy. The irregular contours of the defect lead to an uneven distribution of the radiation doses. The potential to undertreat defects of microscopic involvement may leave residual disease. Tissue morbidity is high at isolated "hot spots" or at locations of excessive dose distribution. The use of a water-filled balloon bolus in conjunction with a balloon-retaining stent can significantly improve treatment efficacy and decrease tissue morbidity. This article describes a technique for the fabrication of a balloon-retaining stent for an orocutaneous defect.


Lip stent for positive pressure in keloid treatment. The fabrication of a device to exert pressure on a keloid of the lip is described. In addition to providing uniform and adjustable compression, it is strong enough to resist distortion. It is also lightweight, easy to insert and remove, comfortable to wear, esthetically pleasing, easy to clean and fabricate, and inexpensive. The prosthesis is a two-component device made from clear acrylic resin assembled with a spring and screw. The stent should remain in place 12 hours a day for 6 to 12 months.


A shade guide for acrylic resin facial prostheses. The value and success of a well-fitting and anatomically correct prosthesis are compromised if the color does not match the adjoining tissue. Color and color science are reviewed to help develop a simplified acrylic resin shade guide to aid in fabricating acrylic resin facial prostheses. This guide will help the clinician obtain a good intrinsic shade and minimize extrinsic coloration.


The effect of a deprogrammer on the position of the terminal transverse horizontal axis of the mandible. This study measured the amount of positional change in the terminal transverse horizontal axis of the mandible that results from altering undesirable neuromuscular influence. Centric relation records were made on 19 healthy subjects before and after deprogramming. The axis was located with a computerized axiograph, and the centric relation records were compared in vivo at the axis location. The positional change of the axis was quantified in three dimensions at an accuracy of +/- 0.05 mm. The net amount of positional change was compared to scores from the temporomandibular joint scale to test for correlation with the potential for developing a temporomandibular disorder. The findings showed that the amount of positional change in the terminal transverse horizontal axis in 18 of 19 healthy patients after 12 hours of deprogramming was less than 0.5 mm and did not correlate with scores from the TMJ Scale.


Effects of posterior teeth replacement on temporomandibular joint sounds: a preliminary report. Previous reports have shown the prevalence of jaw clicking to be significantly higher in a population with missing posterior teeth compared with an dentulous population. This study presents a 2- to 5-year assessment of the effects of posterior teeth replacement on the amplitude of jaw clicking in subjects who were asymptomatic in all respects except jaw clicking. Patients requiring removable partial dentures (RPDs) were clinically and anamnestically examined and temporomandibular joint (TMJ) sounds were recorded using a modified stethoscope attached to an adjustable headgear. Amplified signals were displayed on a strip chart recorder. The amplitude of TMJ sounds at preinsertion of RPDs were 27.5 +/- 17.7 dB at opening, and 11.1 +/- 12.7 dB at closing. Similar values after prosthesis insertion were 15.8 +/- 17.0 dB and 7.4 +/- 7.5 dB, respectively. Paired t test analyses showed significant differences in the amplitude of sound for opening and closing before inserting the prosthesis (p = 0.003) and for opening before and after treatment (p = 0.014). Following replacement of posterior teeth, the clicking amplitude decreased in 68% of recordings, remained unchanged in 11%, and increased in 21%.


Report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry. The committee screened several hundred articles, citing 518 published papers. Some are present quality in research, others provide clinical interest, and some are identified as misleading. New techniques in pulp physiology and pathology are reported. Laser use and techniques in prevention, restorative dentistry, and materials use are reported. Epidemiology of selected diseases and the results of various formulations for treatment are cited. Diagnosis of craniomandibular dysfunction is well represented as well as references to literature reviews and other sophisticated scientific investigation. Research on adhesives is presented in respect to bonding agents for dentin and enamel. Several clinical studies are included, along with customary laboratory reports on several materials.


Resin-bonded cast coverage for fractured posterior teeth. Enamel-dentin fracture without pulpal involvement of intact posterior teeth demands restoration of form and function while preserving as much sound tooth material as possible. A partial-coverage restoration cast in nonprecious metal and air-abraded and bonded to the tooth by an adhesive resin is suggested. The strong bond of the adhesive resin to the enamel and dentin of the tooth and to the air-abraded metal allows for simple fabrication of a cast partial coverage that requires only minimal tooth preparation.


Effect of tray space on the accuracy of monophasic polyvinylsiloxane impressions. The effect of tray space on the dimensional accuracy and stability of impressions made from four brands of monophasic polyvinyl siloxane material was assessed on the recovered stone casts by quantitative and qualitative methods. In general, both evaluation methods agreed that tray space and repeat pour did not affect the accuracy of the dies for individual castings. But disagreement was observed in the findings for fixed partial dentures (FPDs). Quantitative measurement of the interpreparation (IP) dimensions did suggest the possibility of a potential problem when a FPD is cast in one piece because of a significantly reduced distance between the two abutments. However, from the findings of this study it can be concluded that a rigid stock tray can be used with a monophasic polyvinyl siloxane impression material.


The effect of disinfection procedures on flexural properties of denture base acrylic resins. This study evaluates the effects of long-term disinfection immersion on the flexural properties of denture base resins; it was conducted against a background of increasing awareness of the importance of cross-infection control in dental clinics and laboratories. The transverse bend testing procedure used followed that specified in the International Standard for denture base polymers. The results demonstrate that alcohol-based disinfectants are not suitable for use with denture base materials of non-cross-linked acrylic resin.


Linear dimensional variability of three denture base resins after processing and in water storage. It has been shown that denture base resins shrink during curing and expand during storage in water. This investigation measured and compared linear dimensional changes of three denture base resins that occurred during processing and after storage in water for 30, 60, and 90 days. Triad, Accelar 20, and Lucitone 199 long- and short-cured resins were studied, and it was found that Accelar 20 resin exhibited the least curing shrinkage and Lucitone 199 resin short-cured exhibited the most. However, no significant differences occurred between the groups. After 90 days of water storage, the only resin that exhibited a shrinkage from the processed state was Accelar 20. All of the expansion or shrinkage changes were so small that they were not statistically significant and should not be clinically detectable.


A vinyl polysiloxane die used to make interim restorations. A die made of vinyl polysiloxane is a great aid for making interim restorations and for establishing correct gingival contours for finer restorations. This article describes the rationale and procedures for such a procedure.


Effect of glass ionomer liners on bonding strength of laminate veneers. This study compared shear bond strengths of porcelain laminate veneers, fabricated on refractory dies, which were lengthened incisally by 0.5 mm. Specimens were divided into four separate groups. In group A, the teeth were reduced 0.5 mm and the bonding was to enamel. The teeth of the remaining groups were reduced 1.0 mm and the bonding was to dentin. For two of the groups glass ionomer liners were applied before etching. Bonding to enamel was best, with cohesive fractures in porcelain. In the other groups, failure was adhesive in nature, occurring at the resin-tooth interface.


Comparison of the fracture strengths of ceramometal crowns versus several all-ceramic crowns. Fracture resistance to forces applied to the incisal edges of four types of anterior crowns was tested. Ceramometal crowns fractured at significantly higher values (720 psi) than the all-ceramic crowns (approximately 360 psi). No significant difference was found among the fracture values of the Dicor crowns, the aluminous porcelain jackets, and the crowns fabricated from Dicor veneered with aluminous body and incisal porcelain.


The wear of enamel opposing shaded ceramic restorative materials: an in vitro study. The wear rate of intact human enamel opposed by Olympia porcelain gold, Dicor, Ceramco porcelain, and externally shaded Dicor and Ceramco was investigated with an artificial oral environment. The enamel-material couples were subjected to 300,000 masticatory cycles at a maximal occlusal force of 13.4 N while they were continuously bathed with 37 degrees C deionized water. Both the enamel and material surfaces were analyzed by use of a three-dimensional surface monitoring computer program, AnSur, to record the removal of the material and the maximal loss of vertical height. The enamel opposing the externally shaded materials abraded two to five times more than that opposing the unshaded materials and 10 to 15 times more than enamel opposing gold. The wear rates for enamel opposing the gold and unshaded Dicor were similar both in the removal of material and in the loss in vertical height.


The effect of adhesive luting agent-dentinal surface interactions on film thickness. This study investigated the effect of luting agent-dentinal surface interactions on the film thicknesses of new adhesive luting agents. The method was in compliance with American National Standards Institution/American Dental Association (ADA) Specification No. 8 for zinc phosphate cement. In the control groups the luting agents were placed between two glass plates, as described in ADA Specification No. 8, but in the test groups the luting agents were positioned between a glass and a dentinal plate. The materials selected were zinc phosphate cement, glass ionomer cement, polycarboxylate cement, and a resinous cement with a dentinal bonding agent. A two-way analysis of variance was performed, and t tests were computed to compare glass with the dentinal plate within each material. Zinc phosphate and glass ionomer cements exhibited a significant decrease in film thickness when measured in contact with dentin, as compared with contact with the glass plate. However, polycarboxylate cement and the resinous cement with its dentin bonding agent showed a slight nonsignificant increase when contacting dentin, as compared with the glass plate. An explanation was offered and suggestions were made regarding future research.


Shear strength of resin developed by four bonding agents used with cast metal restorations. The evolution of the acid etch technique has made possible a more conservative approach to the fabrication of cast metal restorations. The resin bonding technique, however, places a greater burden for success on the selection of a bonding agent. This study examined the shear bond strength durability of cast metal restorations bonded to tooth structure with one of four metal adhesive bonding agents. Results indicated stronger bonds for restorations cemented with Panavia EX bonding agent than with any of the other bonding agents tested, both with and without exposure to thermal stress. Although it was one of the easier materials with which to work, Panavia EX bonding agent requires the additional step of applying an agent to prevent oxygen contact in the setting process.


Method to measure the polymerization shrinkage of light-cured composites. The polymerization shrinkage of light-cured dental composite resins has been reported to cause a marginal gap between the cavity wall and the restoration, leading to the premature and/or tensile stress failure of the composite restoration. This study measured the volumetric shrinkage of six light-cured posterior composites by measuring specific gravity differences between uncured and cured composite test specimens, using a modified version of ASTM method D792 "Specific Gravity and Density of Plastics by Displacement." The measured volumetric shrinkage ranged from 1.35% to 3.22%.


Amalcore strength recovery following refilling of access preparations with amalgam. After endodontic treatment through an amalgam core, the recommended procedure is to replace the entire core. This study examined the strength achieved by restoring the access openings with dental amalgam and reported the type of failure during strength testing. Seventy-two Dispersalloy 8 x 8 mm cylindrical specimens were produced using controlled condensation pressures. The specimens were randomized in three groups: (1) controls, (2) 3 mm access preparations wetted with mercury-rich amalgam before restoration, and (3) 3 mm access preparations restored unwetted. The specimens tested for compressive strength were separated in two subsets. The unwetted group demonstrated significantly less strength than the control and wetted group (p less than 0.05), while the unwetted and wetted groups revealed significantly less strength than the control group (p less than 0.05). The mean diametral tensile strength recovery for the wetted and unwetted groups was 76% and 69%, respectively. The qualitative assessment of the fracture zones indicated that wetted specimens exhibited more fractures through the new amalgam core than the unwetted specimens (p less than 0.05). It would appear that amalgam refilling of access preparations through amalgam cores has clinical potential.


Bar attachments for overdentures with nonparallel abutments. Bar attachments are easily fabricated and provide increased retention and support for overdentures. Nonparallel root abutments can preclude the routine use of bar attachments unless modifications are made in the design. This article reviews several existing techniques to successfully fabricate bar attachments in overdenture patients with nonparallel abutments. In addition, three alternative methods are presented for placing bar attachments on abutments with divergent roots.


Comparison of the retentive properties of a sleeve cast crown/core system with crowns cemented to conventional cast cores. The retention of the crown to the core substructure is of great importance for a successful restoration. The aim of this study was to compare the retentive values of the Flexi-Cast post and its sleeve crown/core complex with that of a crown cemented to a conventional cast post. Forty single-rooted teeth divided equally into four groups were used. Flexi-Cast crown and cores were cemented to Flexi-Cast posts in groups 1 through 3. Group 4, the control group, comprised crowns cemented to conventional cast cores. Groups 1 through 4 had retentive values of 126.2, 135.5, 185.0, and 79.3 lb, respectively. Statistically, the increase in retention for all sizes of the Flexi-Cast crown and cores when compared with the control cast post and crown was found to be significant (p less than or equal to 0.0001).


The value of radiographic predictors of the rate of mandibular residual ridge resorption. This study tested the relationships between the rate of mandibular residual ridge resorption and the following two variables: cortical thickness at the gonion, and the proportion of cortical bone at the symphysis. These parameters were also compared between men and women. Measurements of cortical thickness at the gonion on panoramic radiographs were compared with similar measurements on lateral cephalometric radiographs. The results showed that neither cortical thickness at the gonion nor the proportion of cortical bone at the symphysis could be used as radiographic predictors of the rate of mandibular bone resorption. The rate of resorption was significantly greater in men than in women, while cortical thickness at the gonion in women was significantly less than that in men. Furthermore, the authors concluded that cephalometric and panoramic measurements should not be used interchangeably.


Changes in the mandibular rest position after removal of remaining teeth and insertion of complete dentures. A 24-month study was conducted to determine changes in the mandibular rest position after removal of the remaining teeth and insertion of complete dentures. A total of 24 patients with at least 10 teeth acting as occlusal stops were included in this study. Serial lateral cephalometric radiographs were made for each patient on four occasions (1) before extraction (2) 7 to 10 days after the initial denture insertion (3) 12 months later, and (4) 24 months later. Two angular measurements and one linear measurement were made for each radiograph and compared. A statistically significant increase in the face rest height with a tendency for posterior mandibular rotation was recorded between stages 1 and 2. This initial posterior rotation was followed by a gradual forward and upward movement, which finally brought the mandibular rest position even below the preextraction levels. The findings confirm the concept of the variability of posture and suggest that the mandibular rest position is an unreliable means of reestablishing the vertical dimension of occlusion that existed before extraction of the natural teeth.


Denture base resins: comparison study of color stability. Several denture base resins have been recently introduced that provide easier or faster processing. Although these materials have adequate strength properties, the color stability is also of interest. This study evaluated the color stability of five denture base acrylic resins and one denture base repair resin. The samples were subjected to conditions of accelerated aging to test color stability. Five samples of each material were processed and aged for 100 and 300 hours. The color stability was quantitatively measured using the Minolta Chroma Meter II. Color measurements were made before weathering and at 100 and 300 hours the color difference delta E was calculated for all samples. At 300 hours the color change of the materials was significantly different at p less than 0.01. It was found that: (1) the color of Lucitone Hy-pro and Acron was least affected by conditions of accelerated aging; (2) Triad, Accelar 20, and Perm demonstrated noticeable color changes; and (3) Compak-20 had an appreciable color change and was the least color-stable of the materials tested.


Fatigue strength of cantilevered metal frameworks for tissue-integrated prostheses. The design of the metal alloy framework in cantilevered sections of fixed tissue-integrated prostheses, is critical. Several cross-sectional designs have been advocated, including the popular L-shaped beam, which permits the economical use of space for tooth placement. The fatigue strengths of 15 L-shaped cantilevered framework sections of the same metal alloy were tested. The castings were divided into three groups of five according to vertical wall heights of 4, 5, and 6 mm. Fatigue durability of each sample was determined by counting the number of cycles of vertical forces required to induce catastrophic failure. Statistical analysis revealed significant differences between all three groups in the cycles counted at failure (p less than 0.0019). Fatigue strengths improved significantly with increasing vertical wall height of the L-shaped cantilevered frameworks. In addition, beam flexure was shown to be indirectly proportional to fatigue strength. Theoretical beam deflection was calculated and shown to correlate with the actual beam deflection during the testing. Theoretical calculations in static bending specific for a cross-sectional design may aid in the predictability of fatigue strength.


Retrieval of the resilient element in an osseointegrated implant system. A fractured apical fragment of the resilient intramobile element within the IMZ dental implant cylinder is difficult to remove. The continued usefulness of the implant will be compromised if the fractured intramobile element is not removed. Two methods of retrieving the apical fragment without causing damage to the internal threads of the implant cylinder are described.


Stress distribution around dental implants: influence of superstructure, length of implants, and height of mandible. The stress distribution around dental implants was investigated by use of a two-dimensional model of the mandible with two implants. A vertical load of 100 N was imposed on abutments or the bar connection. The stress was calculated for a number of superstructures under different loading conditions with the help of the finite element method. The length of the implants and the height of the mandible were also varied. A model with solitary abutments showed a more uniform distribution of the stress when compared with a model with connected abutments. The largest compressive stress was also less in the model without the bar. Using shorter implants did not have a large influence on the stress around the implants. When the height of the mandible was reduced, a substantially larger stress was found in the bone around the implants because of a larger overall deformation of the lower jaw.


Periodontal and prosthodontic treatment of amelogenesis imperfecta: a clinical report. A multidiscipline procedure has been described that provided prosthodontic restoration of esthetics and function for a patient with amelogenesis imperfecta.


Effects of home bleaching preparations on composite resin color. The lightening of teeth is done professionally by exposure to warm hydrogen peroxide solutions or at home with an active bleaching gel of perhydrol urea or carbamide peroxide. This study compared the effects of two commercial bleaching gels on the color of composite resin with those in a previous study using the dental office technique. Commercial composite resins test specimens were exposed to the bleaching gels or water (control) for 312 hours at 37 degrees C at 100% relative humidity. Color change value was calculated with before-and-after solution exposure L*a*b* color values. ANOVA (alpha = 0.01) revealed no differences in the color of the specimens after use of the test solutions. All color change values were less than 2 or the normal limit of visual acuity. No visual color change was evident for these composite resins. The at-home method recorded no shade-altering effects compared with the professional technique, which created a noticeable color change.


Accuracy and bond strength of reversible with irreversible hydrocolloid impression systems: a comparative study. Combinations of three reversible hydrocolloids with five irreversible hydrocolloids were evaluated for dimensional accuracy and bond strength. A stainless steel model representing two teeth prepared for a fixed partial denture was designed for an accuracy study. The recordings were made with a measuring microscope, and the tensile bond strength was determined with an Instron Universal Testing instrument. The accuracy of these materials was clinically acceptable, and the resulting models were suitable. The materials distributed by a common supplier exhibited better tensile strength, although one irreversible hydrocolloid, Jeltrate, performed well in the noncompanion combination groups. This reversible with irreversible hydrocolloid combination impression has an advantage compared with the traditional reversible hydrocolloid impression, because it does not require elaborate, expensive conditioning equipment and water cooled trays.


Fatigue life of three core materials under simulated chewing conditions. There has been an increase in the use of prefabricated post systems to restore endodontically treated teeth. Various restorative materials are being used as core buildups on these posts. The purpose of this study was to compare three core materials that are used with prefabricated stainless steel posts. Two types of prefabricated posts were placed in extracted teeth, followed by core buildups in amalgam, composite resin, or glass ionomer. The teeth were prepared for full cast crowns with the margins of the crown preparation extending 0.5 to 1.0 mm below the margins of the core buildup. Crowns were fabricated and cemented with zinc phosphate cement. A custom-designed chewing machine was used to cyclically load the teeth with vertical and horizontal forces for one million cycles or until failure occurred. Results indicated highly significant differences in the survival of the post-core-crown restorations depending on which core buildup material was used. Amalgam cores had the lowest failure rate, followed by composite resin cores. All teeth restored with crowns over glass-ionomer core buildup failed. The type of prefabricated post used had no effect on the survival of the post-core-crown restorations regardless of the core buildup used.


Recording centric and eccentric occlusal disturbances with a new recording device. A recording device termed a "Kleinrok Functiograph" was introduced to simultaneously document condylar- and tooth-guided mandibular movements on the same plate. The Functiograph instrument permitted objective monitoring of mandibular movement without tooth contact, with all tooth contacts, and allowed analysis of the correlation of these two recordings. After 10 years of conducting investigations on centric occlusion using the Functiograph instrument combined with clinical, radiographic, and electromyographic studies, it was possible to differentiate the horizontal Functiograph recordings of normal and disturbed centric occlusion at a clinically acceptable vertical dimension. Two types of centric occlusal disturbances were classified to accelerate diagnosis and standardize communication.


Tensile bond strengths of three chemical and one electrolytic etching systems for a base metal alloy. This study compared the tensile bond strength of Rexillium III disks etched by three chemical etching systems and the electrochemical etching technique. Cast Rexillium III disks were etched by the following etching systems: electrochemical, Assure-Etch, Met-Etch gel, and Etch-It gel. Thermocycled samples were loaded to failure in tension on an Instron testing machine using a crosshead speed of 5 mm/minute. Samples etched electrochemically yielded significantly greater bond strengths than those etched chemically (p less than 0.05). The rank of the groups was: Electrochemical greater than Assure-Etch = Met-Etch greater than Etch-It. Scanning electron micrograph evaluations of the etching patterns supported the bond strength determinations.


Improved retention of acid-etched fixed partial dentures: a longitudinal study. Debonding of acid-etched fixed partial dentures has been a problem since their introduction. A study was conducted to determine whether this problem could be resolved by modifying the mechanical retention of tooth preparations. Retentive grooves were prepared at the line angles to create mechanical locks for the resin bonded fixed partial denture. The 4-year retention of posterior resin-bonded fixed partial dentures improved from 60% to 95% by the placement of the proximal grooves. This study was conducted in a dental school clinic during a period of 10 to 52 months. The results demonstrated that design modifications were necessary to improve clinical longevity so that the restoration could be considered "permanent" in the traditional sense. The less-experienced dentist may be more confident of the treatment with the recommended modifications and projected longevity.


Microleakage of composite resin and glass ionomer cement restorations in retentive and nonretentive cervical cavity preparations. Ketac Fil glass ionomer cement (GIC) and Scotchbond 2 dentinal bonding agent (DBA)/Silux Plus composite resin restorations were inserted in cervical cavity preparations of extracted human teeth. After thermocycling, the specimens were invested and sectioned longitudinally and horizontally through the center of the restoration. Microleakage was evaluated as a ratio of the extent of methylene blue dye penetration at the tooth-restoration interface. Although all restorations exhibited leakage, both the GIC and bonded composite resin restorations recorded less leakage in retentive than in nonretentive cavity preparations. Composite resin restorations in nonretentive cavity preparations showed significantly more dye penetration toward the pulpal chamber than the GIC restorations. Ketac Fil GIC restorations inserted without a matrix strip exhibited less leakage than those with a matrix strip. The most desirable results were recorded with Scotchbond 2 DBA/Silux Plus composite resin restorations in retentive preparations.


Enhancement of antimicrobial properties of cavity varnish: a preliminary report. Bacterial contamination beneath amalgam restorations has been a problem in restorative dentistry. Cavity varnish improves the marginal seal but possesses no antibacterial properties, and chlorhexidine gluconate is a known antimicrobial substance. This study investigated the efficacy of a chlorhexidine gluconate/cavity varnish mixture against Streptococcus mutans, S. salivarius, and Escherichia coli. The in vitro results indicated that the addition of chlorhexidine gluconate to cavity varnish improved its antimicrobial properties.


The effect of cold treatment on the physical properties of stainless steel and titanium alloy endodontic posts. This study determined whether cold treatment at -96 degrees C affected the mechanical properties of various compositions and sizes of the Flexi-Post system. The experiment was divided into four groups of posts. The two control groups were made up of untreated stainless steel (50 posts) and titanium alloy (40 posts). The two remaining cold-treated groups were made up of stainless steel (50 posts) and titanium alloy (40 posts). In each instance the bending or breaking forces were tested on a universal testing machine. Stainless steel Flexi-Post samples showed a significant (p less than 0.05) increase in strength, whereas titanium alloy posts showed no significant increase in strength as a consequence of the cold treatment.


An in vitro evaluation of simplified quantitative diagnostic aids for detection of Candida albicans. Sensitivities and abilities of quantitative detection for Candida albicans of five simplified diagnostic aids for candidosis or denture stomatitis--Microstix-Candida, Stomastat medium, Mizuno- Takada medium, CA-TG medium, and "milk test"--were examined in vitro, and the characteristics or the indications for clinical use of these summarized.


Dimensional accuracy and stability of acrylic resin denture bases. Proponents of injection molding systems have claimed a number of benefits over conventional press-pack dough molding systems. The aim of this study was to evaluate a recently developed injection (dry heat) procedure of processing compared with press-pack dough molding utilizing three curing cycles. The dimensional accuracy and stability of acrylic resin bases produced by the two molding procedures were compared. Dimensional changes were assessed over a period of 4 months using an optical comparator. The results demonstrate that baseplates produced by the injection molding procedure exhibit less shrinkage than those produced by the conventional press-pack procedures.


Application of the rotational path design concept to a removable partial denture with a distal-extension base. Biomechanical considerations for use of the rotational path design concept to construct a removable partial denture for a patient with a tooth-bounded ridge on one side and a distal-extension ridge on the opposite side are presented. The various axes and arcs of rotation that occur during masticatory function are identified and their effects on the prosthesis and supporting structures are analyzed. Sequential steps in the necessary surveys of the master cast are enumerated. Critical details for the most effective and least deleterious placement of the rigid retentive element on the mesial surface of the posterior molar abutment (on the tooth-bounded ridge) are described.


Effects of environmental factors on maxillofacial elastomers: Part III--Physical properties. The physical properties of four currently used and two recently introduced maxillofacial prosthetic materials were evaluated after the materials were subjected to the following seven environmental variables: natural weathering, normal aging, two types of adhesives, two types of cleaning agents and cosmetics. Ultimate tensile strength, percent elongation, tear strength, and Shore A hardness were evaluated. The physical properties recorded for the currently used materials were consistent with previous studies. Although the properties of the recently introduced materials were similar to those currently in use, one of the new materials, A-2186, showed high strength values, although it was one of the softest materials tested. Unfortunately, this new material lost these advantageous characteristics as it was weakened and made harder by most of the tested environmental variables.


Naturally occurring undercuts in the retention of an interim oculofacial prosthesis. The use of adhesives in retaining maxillofacial prostheses has been advocated and applied for many years. Implant placement has reduced the need for adhesives in some patients but is impractical when ablative surgery is followed by radiation treatment. A technique is described that permits the rapid fabrication of an oculofacial prosthesis that uses naturally occurring orbital undercuts for retention, rather than adhesives that may further irritate radiated tissues.


A study of 589 consecutive implants supporting complete fixed prostheses. Part I: Periodontal aspects. Ninety-one consecutive edentulous patients who had been treated by means of fixed prostheses (n = 103) supported by Brånemark implants (n = 589) were examined. Eighteen fixtures (3%) failed to integrate. After a mean loading time of 32 (range 6 to 80) and 38 months (range 5 to 83) for fixtures in the maxilla and mandible, respectively, an additional 12 fixtures lost integration. The cumulative failure rate for individual fixtures after 6 years was 8.4% and 5% for maxillae and mandibles, respectively. Only one patient had to revert to complete dentures. For fixtures in the maxillae, the mean marginal bone loss was 0.7, 0.1, and 0.2 mm for each of the first 3 years of loading, respectively; for fixtures in mandibles, the corresponding values were 0.7, 0.2, and 0.1 mm. The loss in marginal bone height was equal in both jaws and was not related to bleeding on probing or to the preoperative resorption anatomy.


Altered sensation following mandibular implant surgery: a retrospective study. To determine the prevalence of complications involving altered sensation after implant surgery in the mandible, a retrospective questionnaire study was conducted of 266 patients treated with osseointegrated implants. Of the responding patients (80%), 37% reported altered sensation following implant surgery, with long-term changes occurring in 13% of patients. In more than 60% of symptomatic patients the onset was within 1 week of the first stage of surgery and most frequently involved the lip and chin. Resolution of transient changes usually occurred within 6 months and the majority of patients who reported alterations in sensation believed that the benefits of the implant surgery outweighed the disadvantages experienced. The prevalence of altered sensation was significantly higher in women compared with men and in those with a history of diabetes. These data indicate the need for prospective studies to further evaluate altered sensation after mandibular implant surgery so that specific risk factors can be identified and more accurate information made available to prospective patients.


Kinesiographic three-dimensional evaluation of mandibular border movements: a statistical study in a normal young nonpatient group. Mandibular border movements were studied in a group of 74 healthy young men and women with sound dentitions and class I molar relationships. Movements were directly performed by the subjects and recorded with a mandibular kinesiograph, and slopes of the first millimeters of motion in the anterior and lateral guidances were calculated. In anterior guidance, the sagittal plane slope was steeper in men than in women, whereas the horizontal plane slope showed no gender differences. In the lateral guidances, frontal plane slopes were steeper in men than in women, with no side differences. The horizontal plane slope presented no side or sex differences. Most of the subjects demonstrated asymmetric guidances for both protrusive and the laterotrusive movements. These findings suggest that criteria for defining the norm should include asymptomatic asymmetry instead of strict morphologic symmetric appearance.


Evaluation of a technique for recording temporomandibular joint sounds. Analysis of temporomandibular joints sounds may contribute to the differential diagnosis of temporomandibular joint disorders. In this article an advanced system for the recording of joint sounds is presented. The method proved to be reliable. The problem of filtering out artifacts has been solved to a great extent but not completely. Temporomandibular joint sounds measured with this technique vary considerably in energy, frequency spectrum, and peak-to-peak amplitude over 3 months, as well as within 1 day. These differences seem to reflect natural variations in joint sounds caused by the physical impossibility of performing identical jaw movements. The results indicate that joint sound characteristics do not yet offer a solid basis for inferences concerning the development of temporomandibular joint abnormalities in the clinical setting.


Characterization of acquired denture pellicle from healthy and stomatitis patients. Little information is available about the acquired pellicle layer that is formed on denture surfaces or its role in regulating microbial colonization of the prosthetic surface. Because denture-induced stomatitis is associated with increased numbers of Candida albicans and other microorganisms on the denture surface, the acquired denture pellicle (ADP) may play a role in modulating this colonization. This study examined and compared ADP from healthy patients and patients with stomatitis by chemical and immunochemical methods. The ADP was found to be composed of a selectively adsorbed layer containing salivary amylase, high molecular weight mucin (MG1), lysozyme, albumin, and sIgA. Salivary cystatins, proline-rich proteins, and low molecular weight mucin (MG2) were not detected. ADP amino acid composition was distinct from any of the ductal salivas, but had many similarities with enamel pellicle. Immunoblots of ADP from patients with stomatitis identified additional serum components, degradation products, and C. albicans cell components that were not detected in ADP from healthy patients. Quantification of these molecules in ADP could lead to a diagnostic test for oral mucosal disease underlying a denture base. Identification of specific molecules in denture pellicle that promote adhesion of C. albicans may elucidate a mechanism of fungal cell colonization on the denture surface. Future studies that chemically modify the denture acrylic resin surface to immobilize antimicrobial proteins may be a means of decreasing pathogenic plaque development.


Leaching of nickel, chromium, and beryllium ions from base metal alloy in an artificial oral environment. The use of base metal alloys in dentistry has gained wide popularity in recent years. However, claims of their safety have not been universally accepted. An artificial oral environment capable of reproducing three-dimensional force-movement cycles of human mastication was used to determine whether nickel, chromium, and beryllium ions were leached from base metal alloy. Twelve pairs of crowns were articulated in the following combinations: metal versus metal, metal versus enamel, metal versus porcelain, and metal versus metal without chewing as a control. In a simulated 1-year period of mastication, the results showed that nickel and beryllium metals were released both by dissolution and occlusal wear. These findings suggest that if these conditions occur in the oral cavity, the stability of base-metal alloys is subject to question. Further studies are needed to determine whether the leaching reported has long-term consequences for patients receiving base metal restorations.


An indicator for fitting castings to a die. This article describes a procedure for making an indicator to be used in fitting a casting to a die. It also describes how to use the indicator in the laboratory. The materials for making the indicator are inexpensive, present no health hazard, and are readily available at any arts and crafts store.


Removable magnetic dental attachment that permits magnetic resonance imaging. Magnetic dental attachments cause magnetic resonance image (MRI) degradation. A new magnetic dental attachment that allows removal of magnetic parts to exchange them for nonmagnetic parts was developed and tested. It allows high quality MRI with no change in occlusal vertical dimension. A volunteer test subject with combinations of attachments in place was examined by MRI. The images produced showed no degradation or distortion. Magnetic attachments for overdentures or maxillofacial prostheses should be removable to permit use of MRI.


Temporary soft liners: a modified curing technique to extend liner longevity. A modified curing technique that will extend the useful clinic life of temporary soft liners has been described. This technique offers the following distinct advantages over the traditional method of intraoral curing: (1) a liner that is less porous; (2) a liner that maintains its resilience intraorally for extended periods; (3) a liner that exhibits minimal discoloration over time; (4) increased density that allows adjustments to be made when necessary; and (5) minimized separation from the acrylic resin denture base.


Establishing the role of the clinical nurse specialist in postanesthesia care. The postanesthesia clinical nurse specialist (CNS) is a relatively new and developed role, one that is needed and that can be justified in the specialty of postanesthesia care nursing. This article describes a model with components of expert practitioner, educator, researcher, consultant, and liaison. The sub-role of change agent pervades all other roles of the postanesthesia CNS. Establishment of the role is examined using change theory. Fitting this specialty CNS into the organization is briefly examined through systems theory. Integrating the role into the system requires role making, role taking, and steps to reduce the stress associated with establishing a new role. Communication with involved subsystems, such as postanesthesia staff nurses, management, anesthesia staff, and physicians, is vital to the success of the role. Through education and interaction, significance of the role can be demonstrated to establish the postanesthesia CNS as a vital partner in postanesthesia nursing practice.


Collaborative governance in the postanesthesia care unit. The administration at Schumpert Medical Center, Shreveport, LA, is committed to empowering the nursing staff. Due to this commitment, the postanesthesia nurses developed a collaborative governance program that is based on empowerment. This article discusses how to begin the development and implementation process, address staff concerns, and facilitate acceptance of the finished program by the staff. This program has become a successful model for the collaborative governance program at the author's hospital and has resulted in a stimulating and caring working environment for the professional.


Practical points in the management of malignant hyperthermia. It is the purpose of this article to discuss malignant hyperthermia, including its incidence, pathophysiology, and treatment. Anesthetic implications and PACU nursing considerations are also addressed.


Validation of concepts: the next step in instrument development for postanesthesia studies. Validation of concepts through descriptive research is a major step in instrument development. The concept of hypothermia as observed in the postanesthesia patient is discussed, and data are compared with the North American Nursing Diagnosis criteria of hypothermia. What emerges from the data are items specific to postanesthesia patients, which have been labeled as inadvertent postanesthesia hypothermia (IPH). Thus, the importance of concept analysis in instrument development is emphasized because the omission of this step from instrument development may result in lack of clarity or "fuzzy data" in what is to be measured.


Medical device reporting: a new challenge for perioperative nurses. A variety of illnesses and other complications have been attributed to problems resulting from use of medical devices, implants, and instruments. A new law has implications for all health care facilities using medical devices. The Safe Medical Devices Act (SMDA) of 1990 mandates the reporting of complications related to the use of medical devices to the United States Food and Drug Administration. Reporting requirements of the SMDA could challenge the efficiency of information systems in health care facilities and add to the responsibilities of staff nurses. In the following article, the author discusses some implications of the new law.


Emergence and human conduct.

Emergence and human conduct. Emergence, the occurrence of novel, unpredictable human behavior, is an inherent aspect of human experience on both the individual and collective levels. In this article, we considered the ubiquitous nature of emergent events, indicated some of the ways such events manifest themselves, analyzed the personal and interpersonal processes that give rise to them, and suggested some of their implications for psychology and the other social sciences. Given the inescapable presence of emergence in human conduct, a redefinition of the goals and scope of social science may be desirable.


Memory structure in the processing of advertising messages: how is unusual information represented? Two models of memory structure--schema-copy-plus-tag (Graesser & Nakamura, 1982; Schmidt & Sherman, 1984) and associative-network/depth-of-processing (Craik & Lockhart, 1972; Hastie & Kumar, 1979)--were tested in a 2 x 2 between-subjects design. Type of argument (typical vs. atypical) and measurement interval (immediate vs. 2-day delay in recognition and recall) were manipulated in a print-advertising context. Results indicated that atypical arguments (unusual information) prompt deeper processing of the entire message (implying an associative-network memory structure) rather than some part of the message (as would be hypothesized by the schema-copy-plus-tag formulation) and that this effect prevails under both immediate- and delayed-measurement conditions.


Preventing smoking: evaluating the potential effectiveness of cigarette warnings. We examined the potential effectiveness of U.S. government cigarette warnings in preventing adolescent smoking. In Study 1, 112 seventh graders rated the effectiveness of four currently required warnings and four possible other warnings and answered questions about the meaning of certain words in the warnings. In Study 2, 115 seventh graders attempted to recall the four current warnings; in Study 3, 103 eighth and ninth graders read all eight warnings one day and tried to recall them the next day. In Study 4, 25 seventh graders participated in a focus session in which they discussed the effectiveness of each of the eight warnings. The results of the studies showed that the four different evaluation strategies had convergent validity and that two current warnings and two proposed warnings are significantly more potentially effective than the other two current warnings. Our results also provided information about why some warnings are more potentially effective than others.


Gender, academic achievement, and preferences for cooperative, competitive, and individualistic learning among African-American adolescents. In this study, we investigated the relationships among gender, academic achievement, and student preferences for cooperative, competitive, and individualistic learning in a sample of 136 African-American adolescents enrolled in sixth and seventh grades in a school in Georgia. We used the Learning Preference Scale for Students (LPSS; Barnes, Owens, & Straton, 1978) to measure cooperative, competitive, and individualistic preferences. Three two-way ANOVAs (Gender x Academic Achievement) were conducted, in which the three learning preferences were the dependent variables. Gender had a significant effect on the preference for cooperative learning, with girls reporting a higher preference for this method than boys did. For the other two learning preferences, no significant gender differences were found. Academic achievement did not correlate significantly with any of the three learning preferences. A two-way interaction between gender and academic achievement was observed for competitive learning preferences. Girls' preferences for competition increased as academic achievement increased; boys' preferences for competition decreased as academic achievement increased.


Friendship similarity during early adolescence: gender and racial patterns. We studied the relationship of reciprocity, gender, and racial composition (Caucasian, African American, cross-race) of adolescent friendship dyads to similarity and proximity in 136 young adolescents. We found that adolescents selected friends who were of the same gender and race and that female dyads were more similar than male dyads on verbal achievement and several personality dimensions. Caucasian dyads were more similar than African American dyads on verbal achievement, mental alertness, and dominance. African American adolescents had more contact with their best friends outside school, whereas Caucasian adolescent friends had more in-school contact. African American students had fewer reciprocal relationships than the Caucasian students. Cross-race friendships were less reciprocal than same-race friendships. Race and gender were important in determining friendship patterns. Similarity and proximity were more important than reciprocity in understanding early adolescent friendships.


Personality traits of a group of young adults from different family structures. The impact of parental divorce and remarriage and young adults' gender on second-order personality traits, such as extraversion, anxiety, tough poise and independence, was examined. The responses of 227 young adults on the Sixteen Personality Factor Questionnaire (16PF; Cattell, Eber, & Tatsuoka, 1970) were subjected to a parametric multivariate analysis of variance. Results revealed significant differences between the anxiety scores of the young men and women as well as between those of the three different family-structure groups, but divorce and remarriage was not associated with either positive or negative personality development in this sample.


Self-concept and sociometric outcomes: a comparison of only children and sibling children from urban and rural areas in the People's Republic of China. We investigated differences in self-concept between 360 only children and 555 sibling children in the sixth grade of three urban schools and three rural schools in the People's Republic of China. Peer perceptions and teacher perceptions were also collected using sociometric measures. Self-concept was determined by the Self-Perception Profile for Children (Harter, 1985). Comparisons of sibling children and only children showed no differences on self-concept; however, urban residents had higher self-concept scores than children from rural areas, and boys scored higher than girls. No significant interaction effects between sibling status, gender, and residence were found.


Reaction times and intelligence in Korean children. Nine-year-old Korean children (N = 299) were tested for reaction time (RT) and intelligence measured by Raven's Standard Progressive Matrices. Reaction times were broken into decision times and movement times and into three degrees of complexity. The results showed low but generally statistically significant correlations between decision times and intelligence. Generally, no significant differences existed between movement times and intelligence. Boys showed significantly faster movement times than girls did.


The role of the object in drive cathexis and psychosexual development. Alternate axes are explored in the orthodox formulation of drive cathexis and psychosexual development, with implications for corresponding object relation modes engendered by these processes. Somatic and defensive aspects are shown to impact on the function of the "other" as the individual matures. The separation/individuation process is subsumed into this overall developmental continuum, and the centrality of the object as a focus in cathexis and drive delineation is critically evaluated. The homeostatic notion of equilibration is appealed to in synthesizing the factors emerging from the analysis.


Redescription of Phacodinium metchnikoffi (Ciliophora, Hypotrichida): general morphology and taxonomic position. Living and stained specimens of Phacodinium metchnikoffi, collected near Madrid, Spain, were studied under light microscopy. Infraciliature was stained using a silver-impregnation procedure. The somatic infraciliature is composed of a relatively small number of discontinuous kinetics, formed by groups of few kinetosomes (pallets). The buccal ciliature is composed of an adoral zone of membranelles and a paroral formation otherwise unknown in ciliates, with many short kineties, which lie on a rigid stem. We propose that P. metchnikoffi is a primitive hypotrich and, consequently, we present a new classification system for hypotrichs.


Penetration of the mosquito (Aedes aegypti) midgut wall by the ookinetes of Plasmodium gallinaceum. We observed Plasmodium gallinaceum ookinetes in both intracellular and intercellular positions in the midgut epithelium of the mosquito Aedes aegypti. After epithelial cell invasion intracellular ookinetes lacked a parasitophorous vacuolar membrane and were surrounded solely by their own pellicle. Thus, the ookinete in the midgut epithelium of the mosquito differs from erythrocytic and hepatic stages in that the parasite in the vertebrate host is surrounded by a vacuole. The midgut epithelial cytoplasm around the apical end of invading ookinetes was replaced by fine granular material deprived of normal organelles. Membranous structure was observed within the fine granular area. Most ookinetes were seen intracellularly on the luminal side and intercellularly on the haemocoel side of the midgut epithelial cells. These observations suggest that the ookinete first enters into the midgut epithelial cell, then exists to the space between the epithelial cells and moves to the basal lamina where the ookinete develops to the oocyst.


Trypanosoma cruzi infection of BSC-1 fibroblast cells causes cytoskeletal disruption and changes in intracellular calcium levels. The disruption of vimentin and actin filaments of host BSC-1 fibroblast cells by Trypanosoma cruzi was investigated using a mouse monoclonal anti-vimentin antibody and rhodamine phalloidin, respectively. Indirect immunofluorescence microscopy demonstrated that infection of BSC-1 cells by T. cruzi caused disruption of both cytoskeletal components. The disruption was greater as infection progressed. Mechanisms other than mechanical ones may play a role in the disruption since disrupted cytoskeletal elements were well removed from the parasites. In the determination of intracellular calcium concentrations using Fura-2 AM, infected and uninfected cells both showed an initial increase in intracellular calcium levels. At later times of infection (3 to 5 days), intracellular calcium levels of infected cells were significantly lower than those of control cells. There was no specific localization of intracellular calcium in the infected host cells as determined by image analysis.


Sporulation of Marteilioides branchialis n. sp. (Paramyxea) in the Sydney rock oyster, Saccostrea commercialis: an electron microscope study. The ultrastructure of sporulation of a new parasite, Marteilioides branchialis (Paramyxea), in the Sydney Rock oyster, Saccostrea commercialis, is described. The development is typical of other Paramyxea whereby a stem cell internally cleaves a secondary cell contained within a vacuole. It differs from other species in the phylum in that each secondary cell produces a single spore composed of two concentric cells, one within a vacuole of the other. This type of sporulation represents the simplest of all known Paramyxea. Infection results in focal gill lesions and was observed concurrently with an epizootic of another paramyxean, Marteilia sydneyi.


Surface domains in the pathogenic protozoan Tritrichomonas foetus. The quick-freezing and freeze-etching techniques were used to analyze surface domains of Tritrichomonas foetus. The surface of the protozoan body was not smooth, presenting surface projections, except on the flagellar surface. Images of the actual surface of the anterior flagella revealed the presence of intramembranous particles that form rosettes, as observed on the protoplasmic fracture face. They may represent integral transmembrane proteins exposed at the cell surface. Surface specializations were also observed at the flagella base and where the recurrent flagellum attaches to the cell body.


Determination of taxonomic status of pathogenic and nonpathogenic Entamoeba histolytica zymodemes using isoenzyme analysis. Entamoeba histolytica infection results in either asymptomatic colonization or invasion of host tissues leading generally to clinical symptoms. Zymodemes studies have demonstrated a correlation between isoenzyme profiles and clinical presentation. Thus, strains have been attributed to pathogenic or nonpathogenic groups according to their zymodeme. To determine the taxonomic relationship of these two groups, the isoenzyme profiles of 14 loci of 38 E. histolytica strains (pathogenic and nonpathogenic) and seven strains of other species of the same genus were analyzed. Genetic distance analysis clearly demonstrates the existence of two separate groups within the species E. histolytica.