Quintessence International, 11/1999

Objective: The purpose of this study was to determine the degradation of 10% carbamide peroxide within the first hour of use and the effect of pellicle on the degradation of carbamide peroxide in vivo. Method and materials: Fifteen subjects were assigned to wear nightguard trays filled with bleaching gel for 0.5, 2.5, 5.0, 10.0, 20.0, 40.0, and 60.0 minutes under 2 conditions: (1) subjects did not receive a prophylaxis before each bleaching treatment (pellicle was assumed to be present on the tooth surface); and (2) subjects received prophylaxis to remove pellicle from the tooth surface. At each evaluation time, 3 types of sample were collected: (1) a 'grab sample,' a sample of gel taken with a spatula from the reservoir of the tray on the maxillary right central incisor; (2) the remaining gel from the tray; and (3) the remaining gel scraped from the teeth. The collected gel samples were analyzed for the amount of peroxide using the United States Pharmacopeia-accepted method. Subjects were asked not to swallow the saliva during treatment but to expectorate into a beaker. The collected saliva was analyzed to determine the amount of peroxide. This sample represented the approximate amount of peroxide that subject would ingest during treatment. Results: Pellicle did not affect the degradation of carbamide peroxide for the teeth or grab samples. The degradation of carbamide peroxide was exponential, except during the first 5 minutes, when the degradation rate was much higher. The saliva collected from subjects during use of the bleaching tray revealed an average of 2.1 mg of carbamide peroxide for 1 hour of bleaching treatment. Conclusion: The degradation rate is not affected by the removal of the pellicle.

Dentist-prescribed, at-home bleaching with 10% carbamide peroxide was used to lighten the apparent color of teeth with preexisting porcelain veneers. Veneers had been placed over unprepared, tetracycline-stained teeth; the translucency of the veneers over the discolored teeth resulted in a graying of the veneers. A custom-fitted tray with no reservoirs and no gingival scalloping was fabricated. A 10% carbamide peroxide material was applied nightly for 9 months to achieve the maximum change in the underlying tooth color. The patient was pleased with the apparent color change. Tooth sensitivity during treatment was minimal (lasting 4 days total); the patient treated sensitivity by brushing with a potassium nitrate-containing toothpaste or applying fluoride in the tray. Keywords: at-home bleaching, carbamide peroxide, nightguard vital bleaching, porcelain veneer, tetracycline-stained teeth, tooth bleaching

A discolored, nonvital maxillary right central incisor was bleached with sodium perborate and water, used as a 'walking' bleach. An excellent result was obtained, proving the efficiency of both the intracoronal bleaching technique and the materials employed. A clinical evaluation performed 2 years later revealed that the tooth was slightly stained but esthetically satisfactory.

Objective: The purpose of this study was to determine the instructional characteristics of online continuing dental education courses on the World Wide Web. Method and materials: One hundred fifty-seven online courses offered by 32 providers were reviewed for 34 criteria. Results: Courses of various types spanned a variety of topics. Approximately half of all courses offered continuing dental education credit. The relationship between credit hours and course length was quite variable. Most courses consisted of text and images. Very few courses used advanced media such as video clips. Measured against an index of instructional quality developed for this study, the instructional quality of the courses, in general, was poor. Most for-credit courses contained self-assessment questions, but only 28% of courses scored the questions online. Basic information that was missing on many courses included the authors' names (29%); the intended audience (81%); goals and objectives (77%); and references (85%). In 47% of the courses, there was no opportunity to provide feedback to either the author or the provider. Conclusion: The theoretical advantages of Web-based continuing dental education are numerous, but the currently available online resources are mostly of unacceptable quality.

The ready availability of computers, combined with the advent of sophisticated software development tools, has resulted in a proliferation of dental instructional software. The quality of these products varies widely. Working Group 5 of the Standards Committee for Dental Informatics has published an initial set of guidelines to help course designers develop high-quality instructional materials. In the future, these guidelines will evolve into standards. This article summarizes the guidelines and considers future actions that may be taken once the standards are in place.

Orthodontic treatment was provided after guided tissue regeneration of intrabony defects in 2 patients with periodontal disease. The new attachment obtained by guided tissue regeneration remained stable when subjected to orthodontic forces.

Cyclosporine A, an extremely effective immunosuppressant, is also associated with various untoward effects, including gingival overgrowth. Despite intense clinical and laboratory investigation, the cellular-molecular mechanism through which cyclosporine A simultaneously acts as a selective immunosuppressant while it elicits a connective tissue reaction in the gingiva remains poorly understood. In recent years, cellular and molecular biologic techniques have elucidated a variety of growth factors that control connective tissue homeostasis. Two growth factors known to be major elements in wound repair and connective tissue homeostasis are platelet-derived growth factor and transforming growth factor-b1. Increased gingival levels of these factors may be responsible for promoting fibroblastic proliferation and fibroblastic production of extracellular matrix constituents in overgrown gingival tissues. Expression of these factors has recently been shown to be upregulated in these tissues. The results of these recent studies may provide a foundation for understanding the molecular mechanism involved in the pathogenesis of cyclosporine A-induced gingival overgrowth.

This case history describes the course of disease in a 17-year-old boy with Ehlers-Danlos syndrome type III and early-onset periodontitis. Flow cytometric tests showed a reduced cell count in the specific immune system. Immunoglobulin concentrations in saliva and serum were within normal limits. Infection with T-lymphotropic viruses was excluded. The phagocytic capacity of the peripheral blood polymorphonuclear leukocytes was unimpaired. The anaerobic infection present in the early-onset periodontitis was treated with systemic antibiotic therapy and closed curettage. Following 14 days of this treatment, signs of acute inflammation subsided, and 18 months after therapy ended, a slight gain in clinical attachment was found, and bone growth was visible via radiology. However, a continuing lack of adequate oral hygiene represents a risk to the success of therapy in the long term.