Microshear bond strength of resin luting agents to monolithic zirconia.

The objective of this study was to evaluate the effects of different surface treatments on the microshear bond strength (µSBS) of resin cements to zirconia. Twenty-four zirconia wafers measuring 2.0 × 9.0 × 15.0 mm were sintered and randomly distributed into 3 groups based on the resin cement (n = 8): Panavia F 2.0, NX3, and RelyX Ultimate. The resin cement groups were divided into 4 subgroups based on the surface treatment: a control subgroup (air abrasion with 50-µm alumina particles) and 3 experimental surface treatments (Alloy Primer, Ea-Z-y Primer, and tribochemical silicoating using CoJet Sand). Each surface treatment was applied to the zirconia wafers according to its manufacturer's instructions. The resin cements were mixed and placed in thermoplastic tubes, producing cylinders measuring 0.8 mm in diameter × 2.0 mm in height. Five tubes containing the resin cements were placed on each of the pretreated zirconia wafers, resulting in a sample size of 10 specimens per treatment per resin cement. The luting agents were allowed to cure chemically for 4 minutes and then light cured for 30 seconds. The thermoplastic tubes were removed after 24 hours, and specimens were stored in deionized water (37°C) for 24 hours. A shear force was applied using a wire loop attached to a universal testing machine with a crosshead speed of 0.5 mm/min, and the microshear forces required for failure were recorded. The parametric data were analyzed with a 2-way analysis of variance with post hoc Tukey and Dunnett tests (P < 0.05). The mean (SD) µSBS values ranged from 3.6 (0.9) to 9.3 (2.4) MPa. Surface treatment with Alloy Primer and Ea-Z-y Primer increased the µSBS of the 3 cements compared to their controls, but the difference was not always statistically significant. CoJet Sand only increased the µSBS of Panavia F 2.0. The results suggest that the effects of different surface treatments may be specific for each cement.

Is there an association between Perceptual Ability Test scores and color vision acuity?

OBJECTIVE: The purpose of this study was to determine if there is an association between Perceptual Ability Test (PAT) results and color vision deficiency (CVD). METHODS: Three consecutive classes of first-year dental students (n = 291) voluntarily participated in the study. The Farnsworth-Munsell 100 Hue Color Vision test (FM-100) was administered to students beneath a Macbeth Judge II viewing booth that provided ideal lighting conditions to ascertain CVD. Results of FM-100 test were recorded as total error scores (TES). Color acuity was scored as superior (TES 0-16), average (TES 20-100), or poor (TES > 100). Additional information of age, sex, ethnicity, and time to complete the FM-100 was obtained. Multiple linear regression was used to determine the association between PAT and CVD while adjusting for age, sex, ethnicity, and time to complete the FM-100 test. RESULTS: TES ranged from 0-244. There were 132 students with superior color acuity, 161 with average, and eight with poor acuity. Females performed better than males on the FM-100 test. Time to complete the FM-100 test ranged from 3:40 minutes to 25:12 minutes. There was a strong relationship between PAT scores and CVD (P = 0.0003). A 1-unit increase in PAT scores was found to result in a 9% decrease in TES; indicating that students with higher PAT scores are less likely to have CVD. CONCLUSION: The PAT may be a preliminary screening instrument to identify students who may have CVD. The FM-100 test can then confirm the presence of CVD. Students with CVD may desire to improve dental shade matching skills through targeted training and education.