Efficacy of nightguard vital bleaching technique beyond the borders of a shortened tray

Purpose: The purpose of this study was to determine if bleaching extends beyond the borders of a shortened tray or if a demarcation line is found. Materials and Methods: Fifteen extracted teeth were selected darker than B2 on a Vita Lumin Shade guide (Vita Lumin, Bad Sackingen, Germany). The teeth were mounted in arch-like fashion in dental stone. Alginate impressions were made, and a stone replica of the four arches of teeth was generated. Vacuum-formed bleaching trays were fabricated for each arch, without and with reservoirs, as per the product to be tested. The nonreservoir trays were trimmed to one half the clinical crown length, and the reservoir trays were trimmed 1 mm beyond the border of the half-length reservoir. Measurements were taken from the cementoenamel junction (CEJ) to the tray border for each tooth. The trays averaged 5.1 mm short of the CEJ. The reservoir group was treated with viscous glycerin-based 10% carbamide peroxide (Opalescence, Ultradent Products Inc., South Jordan, Utah); the nonreservoir group with creamy dentifrice-based 10% carbamide peroxide (Platinum, Colgate Oral Pharmaceuticals, Canton, Massachusetts). The trays were loaded and fully seated on the teeth. Excess bleaching material was removed with a toothbrush and water rinse. Each assembly was placed in a humidor with incisal edges down to simulate oral conditions. The process was repeated for fourteen 6- to 8-hour bleaching sessions. Blinded and nonblinded operators determined post-bleaching shades, with consensus reached on differing shades. Results: All teeth demonstrated lightening of 1 to 10 (mean 5.2) increments on the value-oriented shade guide. The bleaching effect extended beyond the tray and no demarcation lines were noted on any of the teeth. CLINICAL SIGNIFICANCE: This in vitro study suggests that successful bleaching occurs beyond the borders of inadvertently shortened trays. The clinician does not necessarily need to remake the tray if the tray does not cover all portions of the tooth.