This study investigated the effects of two different light curing units and two staining solutions on the color stability of a hybrid composite and a nanohybrid composite after different immersion periods. Thirty disk-shaped specimens (10 mm in diameter, 2-mm thick) were fabricated for each of the resin composites, Clearfil AP-X and Filtek Supreme. The specimens were randomly divided into two groups according to the curing unit used: Group I specimens (n = 15) were cured with a quartz-tungsten-halogen (QTH) light for 40 seconds, and Group II specimens (n = 15) were cured with a light-emitting diode (LED) unit in standard mode for 40 seconds. The specimens were incubated in 100% humidity at 37 degrees C for 24 hours. Then, the baseline color values (L*, a*, b*) of each specimen were measured with a spectrophotometer according to the CIELab color scale. After baseline color measurements, five randomly selected specimens from each group (Groups I and II) were immersed in one of two staining solutions (tea or coffee) or distilled water (control). After 1, 7 and 30 days of immersion, the color values of each specimen were remeasured and the color change value (deltaE*ab) calculated. Color changes caused by immersion in tea and coffee for 30 days were only perceptible in the Clearfil AP-X specimens cured with QTH or LED. In the Filtek Supreme specimens, coffee perceptibly stained the teeth after all immersion periods and tea stained after 30 days. Polymerization with QTH or LED did not cause any significant difference in the color stability of Clearfil AP-X or Filtek Supreme. While there were no significant differences between staining solutions in the Clearfil AP-X specimens cured with LED after one and seven days of storage and one day of storage in the QTH cured specimens, significant differences were observed between water and coffee after seven days of storage. In the Filtek Supreme specimens cured with QTH or LED, there were statistically significant differences between the staining solutions after one and seven days of storage. After 30 days of storage, no significant difference was found between tea and coffee in either resin composite cured with QTH or LED. The effect of the staining solutions (tea, coffee) on color changes in composites was immersion time and resin-material dependent.

Nanohybrid and low-shrinkage posterior resin composites, placed with self-etch adhesive systems in posterior teeth, showed satisfactory and similar results after two years. SUMMARYObjective: This study evaluated the clinical performance of a nanohybrid and a low shrinkage posterior composite in Class I and II restorations after two years. Methods and

Dental education consists of both theoretical and practical learning for students to develop competence in treating patients clinically. When dental students encounter practical courses in their irst year as a new educational experience, they must also learn to evaluate themselves. Self-evaluation is an essential skill to learn for dental professionals to keep increasing their competence over the course of their careers. The aim of this study was to compare the assessment scores of second-and thirdyear dental students and the faculty in two consecutive preclinical practical exams in restorative dentistry courses in a dental school in Turkey. Faculty-and student-assigned scores were calculated from two consecutive preclinical examinations on tooth restorations performed on both artiicial casts and phantom patients. The students were formally instructed on grading procedures for tooth preparations, base and restoration placement, and polishing criteria. After each step, each item was assessed by faculty members, the student, and another student. The results indicated that the initial differences between second-year students' assessments of their own preclinical practical ability and that of the faculty decreased among the third-year students. Self-evaluation scores did not indicate whether the third-year students tended to over-or underestimate the quality of their own work. However, the second-year students not only overestimated themselves but thought they were above average. The results point to the need to develop students' self-insight with more exercises and practical training.

ObjectivesThe aim of this study was to evaluate the effects of 3 commercially available mouth rinses on the color stability of 4 different resin-based composite restorative materials.MethodsForty disc-shaped specimens (10x2 mm) were prepared from each of the following materials: A nanofill composite Filtek Supreme XT (3M/Espe, St. Paul, MN, USA); a packable low-shrinkage composite, AeliteLS Packable (BISCO, Inc, Shaumburg, IL, USA); nanoceramic composite resin Ceram-X (Dentsply, Konstanz, Germany); a microhybrid composite, and Aelite All-Purpose Body (BISCO). The specimens were then incubated in distilled water at 37°C for 24 hours. The baseline color values (L*, a*, b*) of each specimen were measured with a colorimeter according to the CIELAB color scale. After baseline color measurements, 10 randomly selected specimens from each group were immersed in 1 of the 3 mouth rinses and distilled water as control. The specimens were stored in 20 mL of each mouth rinse (Oral B Alcohol-free, Listerine Tooth Defense Anti-cavity Fluoride Rinse and Klorhex) for 12 hours. After immersion, the color values of all specimens were remeasured, and the color change value ΔE*ab was calculated. Data were analyzed using a 2-way analysis of variance at a significance level of .05.ResultsAll specimens displayed color changes after immersion, and there was a statistically significant difference among restorative materials and mouth rinses (P<.05); however, the change was not visually perceptible (ΔE*ab<3.3). The interaction between the effect of mouth rinses and type of restorative materials was not statistically significant (P>.05).ConclusionsIt may be concluded that although visually nonperceptible, all resin restorative materials tested showed a color difference after immersion in different mouth rinses.

Bleaching of the tested resin composites did not increase their susceptibility to extrinsic staining in vitro. CLINICAL SIGNIFICANCE Bleaching did not affect staining susceptibility of the tested resin composite restorative materials. (J Esthet Restor Dent 21:407-415, 2009).