Clinical study of tooth shade lightening from dentist-supervised, patient-applied treatment with two 10% carbamide peroxide gels.

PURPOSE: Prescribed, patient-applied tooth lightening agents, or nightguard vital bleaching, typically utilizes a 10% carbamide peroxide agent applied during nocturnal hours. The purpose of this randomized double-blind study was to compare the amount of tooth color change in two groups of subjects using dentist-supervised, patient-applied 10% carbamide peroxide gel. MATERIALS AND METHODS: One group used Opalescence (Ultradent Products Inc., South Jordan, Utah) and the other NiteWhite Excel (Discus Dental, Inc., Los Angeles, California). Evaluation of tooth color for the six maxillary anterior teeth was done using a Vita shade guide at baseline, 1, 2, and 4 weeks. Subjects were instructed to apply the gel nocturnally using a custom-made soft tray 8 hours per day for 2 weeks. The 16 tabs of the shade guide were ranked according to value from darkest to lightest. The number (1-16) that correlated to the shade tab selected as the match for each tooth was the outcome variable. A Kruskal-Wallis one way analysis of variance on ranks was used. RESULTS: The test revealed no statistically significant difference between Opalescence and NiteWhite Excel for lightening the teeth (p = .807). The color change was still significant after 2 weeks without further bleaching activity. The baseline evaluation of the maxillary incisors and canines for all subjects, regardless of group, demonstrated a significant shade difference, with the canines being darker. This difference was not seen after 2 weeks of active bleaching or at the 4-week evaluation. CLINICAL SIGNIFICANCE: In this study comparing bleaching products, patients using Opalescence and NiteWhite Excel experienced a significant change in the color of their teeth relative to baseline values after 2 weeks of active treatment.

Microleakage of root restorations.

This study evaluated the microleakage of various restorative materials placed in root surfaces. A minimum of 20 freshly extracted single-rooted teeth were used for each combination of restorative materials. Four preparations were made on the root surface and each restored with a different material. After thermocycling in dye, the root was cut transversely in several sections through the restoration, and microscopically examined to record the microleakage at the interface between restorative materials and tooth. Results indicated that fewer composite resin specimens allowed microleakage into dentin as compared with either amalgam or glass ionomer materials.

A clinical comparison of dentinal slot retention with metallic pin retention.

Twenty-two pairs of extensive amalgam restorations were placed in 19 patients. One amalgam of each pair had self-threading pin retention, and the other had dentinal slot retention. Evaluations were done at baseline, at one, and two years. After two years, 17 pairs of amalgams were available for evaluations. The data obtained can be summarized as follows: 100% (17) of the slot-retained amalgams were clinically acceptable, whereas 94.1% (16) of the pin-retained amalgams were acceptable. It can be concluded that, in clinical usage, dentinal slot retention is as effective as self-threading pin retention in extensive amalgam restorations.