Performance of Dental Students in Shade Matching: Impact of Training.

OBJECTIVE: The present study evaluated the effect of training on dental students' ability for matching two different shade guides. MATERIALS AND METHODS: The study was conducted in 2012. The participants were 88 male and female undergraduate dental students from Brazil and Portugal, with or without previous color education and vision refractive errors (response rate of 73.33%). They were asked to match a pair set of the shade guides Vita Classical (VC) and Vitapan 3D Master (3DM), with a 20-minutes' rest between each match. The sets were assembled over a neutral gray background and under controlled light. About 7-10 days later, all participants watched a video lecture on color education and repeated the matching procedure. The percentage of matches was calculated and submitted to statistical analysis for the variables gender, geographic region, shade guide and previous color education (Mann-Whitney tests), vision refractive errors (Kruskal-Wallis), and training (Wilcoxon signed rank). All tests were performed at a confidence level of 95%. RESULTS: Training increased the percentage of matches for all groups, except for Portuguese and hyperopic individuals (VC and 3DM) and men (3DM). Previous color education affected VC shade matching before training. Gender, refractive errors, and geographic region did not affect shade matching ability. CONCLUSIONS: Previous education and training in color positively affected shade-matching ability of dental students on shade guide pairing tests. CLINICAL SIGNIFICANCE: The subjectivity of the visual method might not be a clinical concern in daily practice. The human eye can detect small differences in color and visualize the tooth with all its complex geometry, multilayered tissues, and secondary color parameters. Therefore, any color-matching task will be judged by the patient and/or other observers with consideration to this complexity. In other words, visual assessment is paramount to the success/failure of esthetic restorative procedures. The efficiency of the visual color method may be improved by color education through the development of professional color discrimination ability. This would make the students responsible for color selection, reproduction, and evaluation and lead to increased capability over a layperson observer receiving the restorative treatment. (J Esthet Restor Dent 29:E24-E32, 2017).

Effect of desensitizing agents on the microtensile bond strength of two-step etch-and-rinse adhesives to dentin.

Desensitizers can be used to control postoperative sensitivity in adhesive restorations. The aim of this study was to evaluate the effect of desensitizing agents on the bond strength of two-step etch-and-rinse adhesive systems to dentin. Forty-two human molars were sectioned to obtain 3-mm-thick dentin discs. The discs were divided into three groups (n = 14 in each) - no-treatment control group (CT), and oxalic acid [BisBlock (BB)] and calcium phosphate [Desensibilize Nano-P (NP)] desensitizers - before the application of two adhesive systems [Adper Single Bond Plus (SB) and One-Step Plus (OSP)]. A nanoparticle composite resin was used to create a 3-mm-thick build-up. The specimens were stored in distilled water for 24 h before a microtensile bond-strength test was performed. The failure modes were determined using a stereomicroscope at 100 × magnification. Specimens were sectioned perpendicular to the interface for scanning electron microscopy analyses. The CT-SB group exhibited the highest bond strength, differing significantly from BB-SB and BB-OSP groups. Mixed failures were prevalent for all groups. Scanning electron microscopy revealed a continuous hybrid layer and resin tags in all groups. Dentin bond strength of etch-and-rinse adhesive systems was reduced by an oxalic acid desensitizer but was not affected by a calcium phosphate-containing desensitizer.