©Operative Dentistry, 2008, 33-1, 72-78 SUMMARYImproving the adaptation of resin composites during placement is necessary to increase durability and reduce microleakage. Flowable resin liners have been introduced to improve adaptation in composite restorations. In addition, a device that lowers the viscosity of regular dental composites has been introduced (Calset, AdDent Inc, Danbury, CT, USA). This device lowers the viscosity of composites by preheating them to 54.4°C, which should lead to improved adaptation. This study compared microleakage in Class II composite restorations prepared using: 1) preheated resin composite, 2) unheated composite and 3) a flowable liner followed by unheated composite. Class II cavities were prepared on the mesial and distal surfaces of extracted third molars. Ten preparations were restored with resin composite (Esthet-X, Dentsply, York, PA, USA) for each of the following four techniques: Control (Esthet-X with Prime & Bond NT, Dentsply), Flowable (f) (as Control but used Esthet-X Flow liner), Preheated (p) (as Control but with preheating composite to 54.4°C) and Delay (d) (as Preheated but followed by a 15-second delay before curing). The teeth were restored, finished, stored in distilled water for 24 hours, then thermocycled between water bath temperatures of 5°C and 55°C with a one-minute dwell time for 1000 cycles. Tooth apices were sealed with epoxy and varnish was applied to within 1 mm of the restoration margins. The teeth were placed in 0.5% basic fuschin dye for 24 hours, rinsed, then embedded in self-curing resin. The embedded teeth were sectioned mesiodistally with a slow-speed diamond saw, providing multiple sections per restoration. Microleakage was rated by two evaluators using Clinical RelevanceThe results of this study indicate that preheating composites can improve adaptation of resin composites to tooth structure. This technique significantly reduced microleakage. However, delaying light curing of the preheated composite after placement appears to be counterproductive and diminishes the positive effects from the preheating treatment. Flowable liner was less effective than preheating the composite in reducing microleakage.

A prospective in vivo investigation was conducted to determine radiographic and clinical factors associated with contemporary nonsurgical endodontic retreatments. Approximately 1100 failing endodontically treated teeth were screened to determine an appropriate treatment plan. Using magnification, 337 consecutive retreatment cases were evaluated and treated. The vast majority of the retreated cases involved multiple factors. Eighty-five percent of the cases presented with periradicular radiolucencies. Sixty-five percent of the cases demonstrated poor radiographic obturation quality. Associated pain was noted 51% of the time. Forty-two percent of the teeth had untreated canal space. It was statistically significant (Chisquare, p < 0.05) that additional canal space was located and treated in 89% of the cases that had previous radiographic asymmetrical obturations. Evidence of coronal leakage was noted in 13% of the retreated teeth. Tooth number, obturation materials, overfills, and previous surgical retrofillings were also recorded. Recommendations were made that might improve the rate of clinical success.

The purpose of this study was to assess patient preference and product efficacy of three non-prescription products for the symptomatic relief of xerostomia. The study group consisted of 80 individuals with a complaint of chronic (> six months) xerostomia and an unstimulated salivary flow rate of < 0.1 mL/min. The three products--a sorbitol/xylitol-sweetened chewing gum, a sorbitol-sweetened sour lemon lozenge, and a sorbitol/xylitol-sweetened artificial saliva substitute spray--were assigned in a permuted block randomization scheme. Each product was used for two weeks with an interval of one week between trials. The study did not identify any product to be statistically significant in terms of patient preference. Kruskal-Wallis testing revealed no statistical significance (P > 0.589) among the products. No product demonstrated marked efficacy in stimulating salivary output. ANOVA analysis followed by Tukey HSD testing revealed no significant difference between the baseline paraffin-stimulated mean flow rate and the gum- and lozenge-stimulated flow rates.

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