Quintessence International, 03/1990

The literature shows an apparent lack of agreement concerning the histologic morphology of the frena of the oral cavity, particularly relating to the presence or absence of skeletal or striated muscle. The purpose of this study was to do a histologic retrospective analysis of 40 oral frenal biopsy specimens. The results of the study showed that approximately 37.5% of the frena investigated contained skeletal or striated muscle.

Reversible agar agar hydrocolloid remains an excellent, cost-effective impression material. A review of the history of the development of the material and a sound technique for its use are presented.

The design of clasp for a distal extension removable partial denture that helps preserve both the abutment teeth and the tissues of the edentulous ridge is described. The clasp assembly takes advantage of surveyed lingual undercuts to provide support, retention, and stability. It consists of a mesio-occlusal rest, a distolingual L-bar direct retainer that is located on the abutment tooth adjacent to the residual ridge, and a distobuccal stabilizer.

Breakage of a dental cast during its removal from the impression may result in inaccuracies in the finished appliance. The origin and prevention of the factors that can lead to cast breakage are found in the diagnostic phase. Casts of isolated teeth that are long, have marked gingival recession, and have a narrow clinical neck are prone to fracture. If casts of these types of teeth cannot be avoided, measures can be taken to prevent fracture. Wax can be used to thicken teeth with narrow clinical necks or to block out interproximal spaces in adjacent teeth without proximal contacts. The materials used to make the impressions and casts should also be chosen carefully. Methods of removing the cast to avoid fracture include the use of a soldering iron to cut the tray. Once the tray is sectioned, the impression material is free to elongate, and the cast can be removed easily.

Class II, division 1 cases are treated by many different techniques depending on the age of the patient and cause of the malocclusion. To overcome the undesirable effects of headgear on anchor teeth, a removable appliance, the maxillary traction splint, is used with extraoral forces. In this study, 15 patients with maxillary dentoalveolar protrusions and Class II, division 1, malocclusions were treated with a maxillary traction splint. Cephalograms taken before and after treatment and the sagittal skeletal and dental changes were evaluated and quantified. The results showed that use of the maxillary traction splint prior to fixed appliance therapy is effective in correcting dentoalveolar protrusion in growing patients.

The purpose of this study was to evaluate the enamel-sealant interface following the use of standard sealant placement techniques and an air-polishing system. Twenty-five caries-free premolars were extracted and stored in distilled water for 2 days. Five teeth were randomly assigned to each of five treatment groups. The occlusal surface was (1) air polished for 20 seconds, (2) cleaned with pumice for 20 seconds, or (3) not cleaned. Following treatment, 35% orthophosphoric acid was applied for 60 seconds. In two control groups, the acid-etching procedure was eliminated, and one group (4) was air polished for 20 seconds, while the other group (5) was not cleaned. Tinted self-curing sealant was applied to the entire occlusal surface of each tooth. Following the treatment, scanning electron photomicrographs were taken at X 1000 magnification. To evaluate the enamel-resin interface, the number of resin tags were counted by one precalibrated rater. A statistically significant difference was found among the treatment groups and the control groups. Air polishing combined with acid etching resulted in an improved surface for resin wetting as determined by the number of resin tags formed; however, the differences among the treatment groups were not large enough to be statistically significant.

The retentive strength of three zinc oxide-eugenol cements and three noneugenol-containing zinc oxide cements and the effect of the addition of petrolatum on retention were tested. The addition of petrolatum was found to affect retention of the cements significantly. Retention strengths varied from 1.6 kg to 40.0 kg. Of the Class 1, Type 2, systems tested, noneugenol cements had higher retentive values than did the eugenol-containing cements.

The purpose of this study was to (1) compare crevicular fluid flow in smokers and nonsmokers with clinically healthy gingiva; (2) compare crevicular fluid flow of smokers in the areas physically exposed to smoke (maxillary lingual) to that in areas not physically exposed to smoke (maxillary buccal); and (3) compare crevicular fluid flow in smokers and nonsmokers before and after 1 month of (500 mg) twice daily vitamin C supplementation. All sampled areas were required to exhibit clinical health for all measurements (gingival, plaque, and bleeding indices at 0). Ten smoking (at least one pack a day) and ten nonsmoking male dental students were subjects of the study. Areas sampled were midbuccal and midlingual of teeth 3, 5, 12, and 14. Smokers were found to have significantly less crevicular fluid flow than did nonsmokers. Lingual areas of smokers showed no significant difference from buccal areas in crevicular fluid flow. One month of (500 mg) twice daily vitamin C supplementation resulted in a significant decrease in crevicular fluid flow in smokers and nonsmokers. The effect of tobacco smoke on clinically healthy gingiva may be a physiologic result of vasoconstriction rather than a physical irritation

The purpose of this study was to investigate the adaptation of complete maxillary dentures to stone casts processed by the conventional, and two anchoring, methods. The anchoring methods used holes drilled on the cast and a special flange extended onto the posterior aspect of the maxillary cast. Both anchoring methods improved the adaptation of denture bases by minimizing the discrepancy between the denture base and cast. The greatest discrepancies observed in all methods were at the central portion of the posterior border.

Because of a better understanding of the caries process, a decrease in the prevalence of caries, and the rapid development of dental materials, a renewed approach to the treatment of dental caries in the posterior region is possible. A decision tree for the treatment of caries in posterior teeth, taking into account some of the most recent tooth substance-saving treatment options, is presented. These possibilities gradually evolve from nondestructive to conventional cavity preparations. In addition, the preventive Class II restoration is introduced. The application of this conservative attitude toward invasive techniques offers great advantages for both the patient and the dentist. Unfortunately, this approach is time-consuming. Long-term clinical evaluation of the application of the proposed decision tree on a wide scale is needed to confirm its potential benefits or to modify and improve treatment options.