Effect of curing mode of resin composite cements on water sorption, color stability, and biaxial flexural strength.

OBJECTIVES: To determine whether water sorption and solubility of a recently introduced self-adhesive cement is comparable to two clinically tested resin composite cements after thermal aging, and if this is affected by the curing mode. Whether water sorption is correlated with color difference and biaxial flexural strength was also investigated. METHODS: Water sorption and solubility of three resin composite cements {RelyX Universal (RUV), (Panavia V5 (PV5), Panavia SA plus (PSA)} were measured after thermal aging. Disk-shaped specimens were either light-cured or autopolymerized (n = 15 per group). Color difference ΔE00 and biaxial flexural strength were also obtained. RESULTS: Sorption was highest for RUV (auto: 54.9 ± 9.0 µg/mm3, light: 49.7 ± 4.9 µg/mm3), followed by PSA (auto: 37.7 ± 1.4 µg/mm3, light: 34.5 ± 1.1 µg/mm3) and PV5 (auto: 21.7 ± 0.7 µg/mm3, light: 22.1 ± 0.4 µg/mm3). Light-curing reduced solubility values, particularly for RUV (from 60.7 ± 20.8 µg/mm3 to 6.4 ± 0.8 µg/mm3). Color differences of ΔE00 > 1.8 (considered clinically not acceptable) were noted after aging for RUV and PSA. Sorption and ΔE00 values after aging were correlated linearly (R2 = 0.970). Biaxial flexural strength values were highest for PV5 (light: 153.4 ± 15.9 MPa; auto: 133.2 ± 18.0 MPa) and lowest for RUV (light: 99.3 ± 12.8 MPa; auto: 35.1 ± 8.3 MPa). SIGNIFICANCE: Light-curing has beneficial effects on sorption, color stability, and biaxial flexural strength of resin composite cements. Cements containing 2-hydroxymethacrylate such as RUV and PSA are more prone to water sorption and color changes.

Effectiveness of a manual test at the beginning of dental school.

INTRODUCTION: This study analysed whether the SAZAMED (Self-assessment for dentistry studies) manual test conducted as an exercise or examination in the first year of dental studies, and the official aptitude test for medical studies (EMS), can predict future performance of dental students. MATERIALS AND METHODS: Students enrolled in the dental curriculum at the University of Basel between 2009/10 and 2019/20 were categorized: Group A conducted the SAZAMED in the third bachelor year (BA) and second master year (MA), group B practiced in the first and third BA and second MA and group C had to pass the test in the first BA with repetition in the third BA and second MA. SAZAMED comprised (i) wire bending, (ii) modelling sphere and cube, (iii) drawing mirror-inverted and (iv) indirect drawing over a mirror. Comparative variables were the EMS per cent rank and test scores in practical-clinical examinations in the third BA and the second MA. RESULTS: Data were available from 329 students over the 10-year period. Repeaters and dropouts had poorer performance in the first BA SAZAMED than students who did not (p < 0.001). Among the four SAZAMED exercises, mirror-inverted drawing was the strongest predictor of future student performance. The official aptitude test EMS correlated with the third BA certificate (p = 0.012), but failed to predict repeaters and dropouts. CONCLUSION: Since academic success was associated with significantly better scores on the first BA SAZAMED, it is considered a predictor and recommended in addition to the official EMS to identify students in need of intervention programmes or who should choose a different field of study.