Clinical efficacy of polyvinyl siloxane impression materials using the one-step two-viscosity impression technique.

STATEMENT OF PROBLEM: Impression making is a challenging clinical procedure for both patients and dentists. PURPOSE: The purpose of this clinical study was to compare a recently introduced fast-setting polyvinyl siloxane (PVS) impression material with heavy body/light body (HB/LB) combination (Imprint 4; 3M ESPE) (experimental group) with a conventional PVS impression material with HB/LB combination (Imprint 3; 3M ESPE) (control group), using the 1-step 2-viscosity impression technique. MATERIAL AND METHODS: Two definitive impressions (1 of each material combination) were made of 20 crown preparations from 20 participants. The quality of impressions was rated by 3 evaluators (clinical evaluator, clinical operator, and dental technician) and by the patients for the level of comfort and taste of the impression materials. The order in which the 2 impressions were made with each material combination was randomized for each crown preparation. A paired t test for paired means and McNemar test for paired proportions were used for statistical comparisons (α=.05). RESULTS: Participants rated the comfort of the impression making with the experimental group significantly higher than that with the control group (P=.001). No significant differences were found in participants' rating for the taste of the impression materials (P=.46). The viscosity for tray material was rated as significantly better for the control group by the clinical operator (P=.004). The readability of the impression and visibility around the finish line were rated as significantly better for the experimental group than for the control group (P<.001). Except for the ease of removal of the stone (RS), the ratings for the 2 groups by the dental technician were similar. The ease of RS was rated as significantly better for the experimental group (P<.001). Eleven dies from the control and 9 from the experimental group were selected for fabrication of the definitive crowns (P=.65). CONCLUSION: Within the limitations of this clinical study, no significant differences were found in the overall clinical performance of the experimental and the control groups. Impressions made with both materials were clinically acceptable. Participants rated the comfort provided by the experimental group significantly better than that of the control group.

A clinical comparison of two vinyl polysiloxane impression materials using the one-step technique.

STATEMENT OF PROBLEM: Impression making remains a challenging procedure due to the potential for voids and tears, which may adversely affect the precise fabrication of indirect restorations. PURPOSE: The purpose of this study was to compare vinyl polysiloxane (VPS) impression materials using the 1-step impression technique for single and 2-unit crowns. MATERIAL AND METHODS: Twenty subjects provided informed consent, and two 1-step double-phase master impressions (1 of each material combination) were made of 25 crown preparations. A relatively new VPS material with heavy-body (HB) and light-body (LB) viscosities, which was defined as the experimental group (Imprint 3), was compared to a standard VPS with medium-body (MB) and light-body (LB) viscosities, which was defined as the control group (Aquasil Ultra). Stock trays were used to make a total of 40 master impressions. The order of impression making was randomized as related to the different groups. Impressions were rated visually by 2 evaluators (a clinician and a dental technician). The rating resulted in ordinally structured data for the outcome variables (alpha: excellent, no defects; bravo: acceptable, small defects; charlie: defects require impression to be remade; delta: unacceptable, defects at finish line). Definitive casts made of impressions rated as alpha or bravo were further rated by a dental technician, and that which was rated best was used for making the definitive crown. RESULTS: Twenty-three (92%) of the experimental and 24 (96%) of the control impressions were rated as alpha or bravo by the evaluator (P=.57; McNemar's test for clustered paired proportions using GEE). All 25 dies in the definitive casts of both groups were rated as alpha or bravo by the dental technician. Fifteen dies were selected from the control group and 10 from the experimental group for the fabrication of the definitive crowns (P=.41; 1-sample binomial test for clustered data using GEE). CONCLUSIONS: Within the limitations of this clinical study, there was no statistical difference in the clinical performance of the experimental and control VPS impression materials. (J Prosthet Dent 2009;102:179-186).

Flexural and shear strengths of ZrO2 and a high-noble alloy bonded to their corresponding porcelains.

STATEMENT OF PROBLEM: Flexural and shear strength between ZrO(2) cores and veneering porcelains require investigation to facilitate clinical use. PURPOSE: The purpose of this study was to assess the strength of ZrO(2) and a high-noble alloy with corresponding porcelains. MATERIAL AND METHODS: Forty rectanglar (12 x 10 x 3 mm) and 20 cylindrical (5 x 5 mm) specimens of ZrO(2) (Lava) and high-noble alloy (Olympia) were fabricated for 4-point flexural testing and shear testing. IPS d.SIGN veneering porcelain for high-noble alloy and Lava Ceram, 2 mm thick, were fired, joining the 2 corresponding rectangles of high-noble alloy and ZrO(2) to create flexural test specimens. The same types of veneering porcelains, 3 mm in thickness, were fired on 1 side of the corresponding high-noble alloy and ZrO(2) cylinders to produce shear specimens. The flexural and shear specimens were divided into 4 groups (n=10); metal ceramic and ZrO(2) with and without thermal cycling. Thermal cycling was performed at 5 degrees C and 55 degrees C for 5000 cycles with a 20-second dwell time. Flexural and shear tests were performed using a universal testing machine. Fractures were characterized using a stereomicroscope and SEM. Data were analyzed with a 1-way ANOVA and Tukey HSD post hoc test (alpha=.05). RESULTS: The ANOVA revealed a significant difference among flexural groups (P=.008) and among shear groups (P<.001). In flexure, the Tukey HSD post hoc test revealed a significant difference (P=.005) between metal ceramic thermal cycled and ZrO(2) thermal cycled groups, with a higher value of 91.01 (22.33) MPa for the metal ceramic group. In shear, the Tukey HSD post hoc test revealed a significant difference between metal ceramic and ZrO(2) groups, with a higher value of 82.00 (22.49) MPa for the metal ceramic group. Thermal cycling did not have a significant effect on flexure or shear strength. ZrO(2) specimens failed cohesively within the veneering porcelain. CONCLUSIONS: There were no significant differences among the groups in flexure, except between thermal cycled metal ceramic and ZrO(2) groups. There was a significant difference between the metal ceramic and ZrO(2) groups in shear. Thermal cycling did not have a clear effect among different groups in both tests.

Utilization of multiple restorative materials in full-mouth rehabilitation: a clinical report.

UNLABELLED: Many different restorative materials are currently available for use in modern dentistry. Clinicians and dental technicians should be able to choose the most suitable materials for each patient based on research, anecdotal evidence, clinical experience, as well as patient's expectations and desires. The purpose of this article is to share the challenges presented in full-mouth rehabilitation and to describe the considerations in selecting three different restorative materials to achieve a successful restoration in terms of biomechanics, function, and esthetics. CLINICAL SIGNIFICANCE: Interdisciplinary treatment planning, knowledge of available restorative materials, sequencing treatment modalities, and adequate communication between all parties involved are key to a successful treatment outcome when pursuing full-mouth restorative rehabilitation.