Quintessence International, 06/2002

Restoring a tooth with an inadequate contact point and root proximity is a challenge to the practitioner. Ignoring such situations or making compromises in the treatment plan may hinder a successful treatment outcome. Treatment options include strategic extractions, sectional orthodontics, and minor orthodontic movements. The purpose of this article is to discuss the clinical problems and difficulties arising from this situation and to present a modified treatment modality through two case reports. Elastic separating rings, which open an interdental space for placing orthodontic appliances, can be modified to serve as a preprosthetic means for solving mesiodistal crowding of teeth in daily practice. The classic method is modified by the use of elastic rings in sequentially increased thickness, so that the space gained with one ring is followed and increased with a thicker one. An orthodontic background and special instruments are not necessary.

Modern all-ceramic systems offer a highly esthetic, biocompatible, and functional alternative to traditional restorative materials. Such systems allow for a wide range of indications, from inlays to multiple-unit fixed partial dentures, and are increasingly used in posterior regions of the mouth. Many of these systems have been introduced to the market only recently. However, new materials and techniques should be followed up and their clinical performance proven for at least 5 years before they become routine modalities of treatment. This article reviews the current literature and scientific data on the long-term success of all-ceramic restorations in the posterior region and compares and discusses alternative treatment options.

There is worldwide interest in and increasing usage of the conservative atraumatic restorative treatment technique or approach for the restoration of primary and permanent teeth. However, most published data on the clinical performance of the newer, high-strength esthetic conventional glass-ionomer restorative cements marketed for the procedure have been derived from short-term studies. There have been very few reports comparing different types of restorative materials and methods of cavity preparation. In primary teeth, after 1 year, success rates have been approximately 80% to 95% for Class I and Class V single-surface restorations, 55% to 75% for Class II multisurface restorations, and 35% to 55% for Class III and Class IV restorations. In permanent teeth, after 2 to 3 years, success rates have been approximately 90% for Class I and Class V single-surface restorations, but little data have been reported for other restoration classes. Failures usually result from restoration losses, fractures, and wear. Further improvements in the design of hand instruments and in the mechanical properties of the newer glass-ionomer cements are required. Currently, use of the atraumatic restorative treatment approach should be restricted to restoration of single-surface caries lesions, especially in permanent teeth, and to sealing of occlusal fissures in selected teeth.

Objective: The purposes of this study were to determine the variation in maxillary and mandibular vertical measurements made from panoramic radiographs and to assess differences in measurements between dentate and edentulous jaws. Method and materials: A total of 192 alveolar ridges (96 dentate and 96 edentulous) were examined. The mean ages of the dentate and edentulous groups were 51.05 and 59.98 years, respectively. Measurements were made from reference lines drawn from anatomic landmarks on standardized panoramic radiographs. Results: In the dentate group, there was no statistically significant difference between men and women in the height of the maxilla. However, the height of the mandible was significantly greater in men than in women. In the edentulous group, the heights of the maxilla at the anterior and first premolar regions were significantly greater in men than in women. In the same group, mandibular heights were also significantly greater in men than in women. Reductions in the height of the edentulous mandible and maxilla were significantly more pronounced in women than in men. The decrease in the vertical height of the maxilla was not statistically significant in men. Conclusion: There are differences between the sexes in alveolar ridge resorption after tooth loss.

Objective: The objective of this study was to compare the microstructures of teeth, natural opals, and opal dental enamel porcelains to examine the mechanisms that cause opalescence. Method and materials: Four dental porcelains, a natural opal mineral, and a human tooth were examined. Replicas were assessed in transmission electron microscopy for features that would cause opalescence. Enamel dental porcelains denoted as "light" were selected for the study. X-ray diffraction and color analyses of the porcelains were also performed. Results: All the materials were opalescent, to varying degrees. The porcelains with fewer microscopic features were less opalescent. The presence of dispersed particles or a phase-separated glass was found to cause opalescence in dental porcelains. Conclusion: A phase-separated glass in one enamel porcelain best resembled the microstructure of natural opal mineral and teeth, and this was the most "opalescent" material.

Objectives: The aim of this study was to assess the ability of three low-viscosity resin systems (Unibond, Single Bond, and Fluorseal), used as rebonding agents, and a specific surface-penetrating sealant (Fortify) to prevent microleakage in Class V resin composite restorations. Method and materials: Fifty Class V cavities with the occlusal margin in enamel and the cervical margin in dentin and cementum were prepared on both the buccal and lingual surfaces of sound extracted premolars and restored with a hybrid light-cured resin composite. After finishing and polishing, restorations were randomly assigned to one of five equal groups (n = 10): a control, without surface sealing, and four experimental groups in which margins were etched and rebonded. Specimens were thermocycled, immersed in a 50% silver nitrate solution, sectioned longitudinally, and analyzed for leakage at the occlusal and cervical interfaces. Results: Statistical analysis showed significantly less leakage at the enamel margins for all groups. Fortify and Unibond were statistically similar and provided better marginal sealing at dentin and cementum interfaces. Fluorseal showed the poorest ability to prevent microleakage. Conclusion: The rebonding technique may substantially minimize microleakage at dentin and cementum margins of composite restorations, when a resin system with sufficiently low viscosity is used as a surface sealant, regardless of whether it has been specified for such a purpose.

Objective: Different types of fibers have been added to polymer materials to improve their mechanical properties. Glass fibers have been used in either continuous or woven form as a strengthening material. The aim of this study was to investigate the effect of a new glass fiber reinforcement system on the flexural strength of three different denture base resins (heat polymerized, autopolymerized, and photopolymerized). Method and materials: Ninety specimens were formed in a specially designed mold to produce identical specimens in accordance with each manufacturer's recommendations. Results: The fibers of Stick and Stick Net were well impregnated with the resin of polymer matrix. Stick and Stick Net reinforcement significantly enhanced the flexural strength of the tested specimens. In all groups, specimens reinforced with Stick glass fibers exhibited the highest flexural strength, followed by Stick Net glass fibers. The control group specimens without fiber exhibited the lowest values. Conclusion: The process of reinforcement of denture base resins with glass fiber may be a useful means of strengthening denture bases beyond their normal limits.

Objective: The purpose of this study was to retrospectively assess the success of endodontic treatment that had been guided by audiometric (electronic) measurement. Method and materials: The lengths of 66 infected root canals that demonstrated periapical pathosis were accurately measured by the Sono-Explorer before root canal obturation. The results over time intervals of 1 month to 20 years were evaluated on the basis of radiographic examinations. Results: The rate of successful treatment was 90.4% for short-filled root canals, 94.5% for flush-filled root canals, and a low 50.0% for long-filled root canals. The rate of successful endodontic therapy was 87.8% for restorations that did not exceed the apical foramen but reached the apical constriction and 95.3% if cases in which the apical radiolucencies were disappearing were included as successes. If cases of unintentional long-filling (overextension) were excluded, the success rate was as high as 98.4%. Conclusion: The poor performance of overfilled root canals indicates that practitioners should not overextend these restorations. Use of the Sono-Explorer aided successful treatment of infected root canals.