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ObjectivesTo evaluate the compressive modulus, translucency, and light curing irradiance transmittance of four clear polyvinyl siloxane (PVS) materials used for the injection molding technique at varying thicknesses, and to assess the correlation between color parameters and irradiance transmittance.Materials and MethodsFour clear PVS materials (Exaclear, Clear Bite Matrix, Affinity Crystal, and Memosil 2) were used in this study. Compressive modulus was measured by compressing cylindrical PVS specimens (n = 9; d = 10 mm; t = 6 mm) up to 30% strain using a universal testing machine. For the translucency analysis and irradiance transmittance, specimens (n = 5) were fabricated with five different thicknesses (d = 12 mm and t = 2, 4, 6, 8 and 10 mm). The L*, a, *b* values of specimens were obtained using a CIELab spectrophotometer (CMD‐700, Konica Minolta) with calibrated white and black tiles; the translucency parameter was calculated. The same specimens were placed onto a spectrophotometer (MARC Light Collector) to measure irradiance transmitted through the specimens from a light curing unit (Valo Corded, Ultradent). Data were analyzed using analysis of variance (ANOVA) with Tukey post hoc test and the correlation between translucency and irradiance transmittance of materials for each thickness was evaluated using Pearson's correlation.ResultsCompressive modulus differences in PVS materials were significant (one‐way ANOVA: df = 3, F = 76.27, p < 0.001); Affinity and Memosil 2 were highest with no significant difference between them (Tukey: t = −1.62; p = 0.382). Clear Bite was higher than Exaclear (Tukey: t = −3.70; p = 0.004). Exaclear was lowest. Translucency decreased with thickness (Two‐way ANOVA: df = 3, F = 586.53, p < 0.001; thickness: df = 4, F = 1389.34, p < 0.001). Exaclear was most translucent at all thicknesses. L*, a*, b* values varied by material and thickness (L*: df = 3, F = 1213.32, p < 0.001; a*: df = 3, F = 10766.8, p < 0.001; b*: df = 3, F = 3260.42, p < 0.001). Memosil 2 had lowest b* values. Irradiance transmittance was affected by material and thickness (Two‐way ANOVA: df = 4, F = 2388.86, p < 0.001). Exaclear had highest irradiance transmission, surpassing control at >6 mm. Violet/blue irradiance ratio decreased with thickness; Exaclear maintained a constant ratio, indicating preserved violet irradiance. There was a strong positive correlation between translucency and light irradiance (Pearson's r = 0.97, R2 = 0.86–0.96). Radiant exposure analysis suggests adjusting the curing time based on PVS thickness for optimal exposure (10 J/cm2) is achievable within 13–14 s for <2 mm and 21–30 s for 8–10 mm with Clear Bite, Affinity, and Memosil 2; whereas Exaclear requires less time.ConclusionsCompressive modulus in clear PVS materials varied by type; Affinity and Memosil 2 demonstrate higher modulus, offering more stability of the clear mold. Translucency and irradiance transmission through clear PVS materials decreased as their thickness increased, yet Exaclear exceled in maintaining high translucency and superior light transmission capabilities. Additionally, there is a strong positive linear correlation between translucency and light irradiance transmittance, offering a method to adjust curing times effectively based on material translucency.Clinical SignificanceThe light curing time to adequately polymerize composite through clear impression material may need to be increased, particularly with thicker matrices or less translucent materials.
ObjectivesTo evaluate the compressive modulus, translucency, and light curing irradiance transmittance of four clear polyvinyl siloxane (PVS) materials used for the injection molding technique at varying thicknesses, and to assess the correlation between color parameters and irradiance transmittance.Materials and MethodsFour clear PVS materials (Exaclear, Clear Bite Matrix, Affinity Crystal, and Memosil 2) were used in this study. Compressive modulus was measured by compressing cylindrical PVS specimens (n = 9; d = 10 mm; t = 6 mm) up to 30% strain using a universal testing machine. For the translucency analysis and irradiance transmittance, specimens (n = 5) were fabricated with five different thicknesses (d = 12 mm and t = 2, 4, 6, 8 and 10 mm). The L*, a, *b* values of specimens were obtained using a CIELab spectrophotometer (CMD‐700, Konica Minolta) with calibrated white and black tiles; the translucency parameter was calculated. The same specimens were placed onto a spectrophotometer (MARC Light Collector) to measure irradiance transmitted through the specimens from a light curing unit (Valo Corded, Ultradent). Data were analyzed using analysis of variance (ANOVA) with Tukey post hoc test and the correlation between translucency and irradiance transmittance of materials for each thickness was evaluated using Pearson's correlation.ResultsCompressive modulus differences in PVS materials were significant (one‐way ANOVA: df = 3, F = 76.27, p < 0.001); Affinity and Memosil 2 were highest with no significant difference between them (Tukey: t = −1.62; p = 0.382). Clear Bite was higher than Exaclear (Tukey: t = −3.70; p = 0.004). Exaclear was lowest. Translucency decreased with thickness (Two‐way ANOVA: df = 3, F = 586.53, p < 0.001; thickness: df = 4, F = 1389.34, p < 0.001). Exaclear was most translucent at all thicknesses. L*, a*, b* values varied by material and thickness (L*: df = 3, F = 1213.32, p < 0.001; a*: df = 3, F = 10766.8, p < 0.001; b*: df = 3, F = 3260.42, p < 0.001). Memosil 2 had lowest b* values. Irradiance transmittance was affected by material and thickness (Two‐way ANOVA: df = 4, F = 2388.86, p < 0.001). Exaclear had highest irradiance transmission, surpassing control at >6 mm. Violet/blue irradiance ratio decreased with thickness; Exaclear maintained a constant ratio, indicating preserved violet irradiance. There was a strong positive correlation between translucency and light irradiance (Pearson's r = 0.97, R2 = 0.86–0.96). Radiant exposure analysis suggests adjusting the curing time based on PVS thickness for optimal exposure (10 J/cm2) is achievable within 13–14 s for <2 mm and 21–30 s for 8–10 mm with Clear Bite, Affinity, and Memosil 2; whereas Exaclear requires less time.ConclusionsCompressive modulus in clear PVS materials varied by type; Affinity and Memosil 2 demonstrate higher modulus, offering more stability of the clear mold. Translucency and irradiance transmission through clear PVS materials decreased as their thickness increased, yet Exaclear exceled in maintaining high translucency and superior light transmission capabilities. Additionally, there is a strong positive linear correlation between translucency and light irradiance transmittance, offering a method to adjust curing times effectively based on material translucency.Clinical SignificanceThe light curing time to adequately polymerize composite through clear impression material may need to be increased, particularly with thicker matrices or less translucent materials.
Anterior teeth restoration represents a challenge for dentists, who often rely on the dental technician’s wax-up. The proposed Stratified Stamp Technique (SST) allows for clinically reproducing the wax-up in a quick and easy way. A patient with fractures and discoloration on the upper central incisors was treated with resin-based composite direct restorations. Using SST, a 1 mm thick thermoformed polyethylene-terephthalate-glycol (PETG) template, based on the technician’s wax-up, was produced. Enamel Selective Area Reduction (SAR) was performed to guarantee adequate space for the restorations, and the fracture margins were rounded and finished. Traditional layering procedures according to the five color dimensions of teeth were performed, except for the final labial layer, which was realized with warm composite loaded inside the template and polymerized through it, in order to ensure accurate tooth morphology reproduction. SST offers a reliable method for transferring technician’s wax-up morphology to direct composite restorations in anterior teeth. Compared with other methods, SST allows for better isolation with a rubber dam and permits traditional layering with multiple composite shades, thus leading to satisfactory esthetic outcomes.
Background: Model alignment in cases of erosive tooth wear can be challenging, and no method has been reported to outweigh the others. Methods: Extracted human teeth were mounted on two models and scanned at different times, from 1 h to 2 weeks, with an intraoral scanner (3Shape TRIOS 4) before and after immersion in Monster® energy drink and tap water. The scans were superimposed (3Shape TRIOS Patient Monitoring, Version 2.2.3.3, 3Shape A/S, Copengagen, Denmark). Best fit, best-fit tooth comparison, reference best fit using fillings, and palatal rugae as reference points were used for alignment. Surface profile differences were calculated in a cross-section view. The nonparametric Bland–Altman and Kruskal–Wallis tests were used. Results: First, statistically significant differences were marked after 4 days of immersion. The measurements obtained after 2 weeks of immersion were statistically significantly different from the measurements obtained at the different time points until 1 week. No statistically significant differences (p < 0.05) were observed among the alignment methods at any time. Conclusion: In comparison to the best-fit model, both palatal rugae and fillings can be used. The best-fit tooth comparison method is a reliable option; however, it should be used with caution in cases of major surface loss.
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