10-Year Clinical Comparative Study of Ceramic and Composite Veneered Metal Crowns.

The rejection of composite veneerings in fixed partial dentures is primarily caused by the inadequacy of the bonds between the metal framework and the composite veneering. The development of improved veneering composites necessitates an investigation of their clinical suitability compared with ceramic materials. Nineteen patients with at least two suitable, adjacent natural teeth for crowning were treated with 64 high noble alloy crowns. The adjacent crowns were veneered with ceramic (IPS inline) and composite materials (SR Adoro). Seven follow-up examinations were carried out over a period of 10 years. The crowns were investigated for mechanical defects, periodontal parameters, and discolorations. The survival rates of the ceramic veneered metal crowns (CeMCs) and composite veneered metal crowns (CoMCs) at the 10-year follow-up were 87.1 and 87.9%, respectively. The success rates of the crowns after 10 years were 83.9% for CeMCs and 51.5% for CoMCs (log-rank test, p = 0.009). No significant differences between the groups were found in the periodontal parameters (Kruskal-Wallis one-way analysis of variance, ANOVA p ⟩ 0.05). After 10 years, discoloration patterns of the two materials differed significantly (Mann-Whitney-U-test, p = 0.017). Thus, despite the improvements associated with CoMCs, CeMCs remain the gold standard for veneered metal crowns.

Shade Stability of Polymer Infiltrated and Resin Nano Ceramic Crowns after Dynamic Chewing Simulation.

OBJECTIVE: Investigation of the shade stability of polymer-infiltrated and resin nano ceramic crowns before and after artificial aging. METHOD: 40 identical crowns of each of the materials VITA Enamic (VE) and Lava Ultimate (LU) were manufactured. Half of the crowns went through a dynamic chewing simulation (CS) with thermocycling. Material subgroups: 1. VE, 2. VE/CS, 3. LU, 4. LU/CS (each n=20). These were divided into 4 groups (n=5) and distributed in usual stain solutions. The shade of each crown was measured occlusally and vestibularly before and after insertion using a spectrophotometer (n=5). The data were analyzed using ANOVA and Tukey's test (p≤0.05). RESULTS: Sum scores (SSC) of the occlusal ΔE values: LU/CS: 7.99, VE: 5.75 VE/CS: 5.44, LU: 5.17. The total sum of the SSC yielded, for the materials: SSCtotal(VE): 20.0 and SSCtotal(LU): 24.0. SIGNIFICANCE: Occlusally, there were significant shade differences for VE/CS (p=0.025) and LU/CS (p=0.014) between red wine and distilled water. LU/CS is significantly more clearly stained occlusally by coffee in comparison to the other three material subgroups (VE: p=0.007, LU: p=0.026, VE/CS: p=0.013). CONCLUSIONS: The shade stability of VITA Enamic crowns is superior to that of Lava Ultimate crowns. Only Lava Ultimate is affected by chewing simulation.

Elaborative feedback in clinical dental teaching-An assessment from the students' perspective.

INTRODUCTION: The aim of this prospective learning research study is to examine the impact of structured elaborative feedback in clinical dental skills teaching from the students' perspective. MATERIAL AND METHODS: A total of 60 dental students participated in the study. The mean average age was 23 years (20-40 years), of which 37 were female (61.7%) and 23 male (38.3%). The participants were randomly divided into a study and control group (n=30 each). The curriculum for clinical tooth-shade differentiation is a complete educational module. Recording of shade taking was carried out on the phantom patient using clinically simulated settings with elaborative feedback in the study group. Pre-test (begin of module T1) and post-test (end of module T2) questionnaires were used to assess knowledge and interest in connection with elaborative feedback. Subjective learning success from the students' perspective and the acceptance of the learning environment were recorded using a questionnaire at the end of the module. The responses corresponded to a Likert scale. The STATA program (Stata/MP 12, StataCorp, CollegeStation, USA) was used for statistical analyses (p<0.05). RESULTS: A clear improvement in the quality of response in both groups was observed for questions regarding knowledge of the content and interest (p<0.001). The highest values were achieved at reference time T2 for "Practical steps with digital tooth-shade measurement devices" in the study group. Subjective success in terms of learning and the acceptance of the learning environment tended to be rated more highly in the study group. These results corresponded with the reduction of errors during the practical exercises. All participants (100%) in the study group found individual feedback to be helpful.

Randomized multi-centre study on the effect of training on tooth shade matching.

OBJECTIVES: The aim of this study was to find out whether Toothguide Trainer, TT, and Toothguide Training Box, TTB, show any training effects, independent of the shade guide chosen. METHODS: Students from four dental schools (N=78) were included in this study. The participants were randomized into a study, 42 students (age range: 19-27 years; 69% female, 31% male) and a control group of 36 students (age range: 19-30 years; 57% female, 43% male). The study group started with a double blind introduction test, followed by the TT and TTB training, finishing with the final test. The control group only passed the introduction and - after a break - the final test. Eight randomly chosen samples, seven of the Vita classical and one of the 3D-Master colour scale, were marked by barcodes. Colour matching was arranged by the Vita classical scale. RESULTS: The results of the pre- and final tests of both groups were combined. For every sample, the value ΔE was determined. The summation of all eight samples from the introduction and final tests offered a summarized ΔE value. The differences between introduction and final tests revealed the individual learning success. 47.6% of the study group showed statistically significant better results than the control group, 33% (p=0.031). CONCLUSION: TT and TTB show a positive effect of training on tooth shade matching independent of the colour scale used. CLINICAL SIGNIFICANCE: Visual shade taking is the most frequent clinical method for shade determination. To increase better results in visual colour matching, TT and TTB training is used. This is the first study examining the training effect of TT and TTB using Vita classical scale.