Microleakage of chairside moulded, 3D-printed and milled provisional restorations using a curve-fit approach.

The purpose of this study was to evaluate and measure the microleakage inhibiting quality of provisional restorations manufactured using computer-aided manufacturing, 3D printing, and chairside molded provisional restorative materials. Fifteen provisional restorations each from 3D printed, milled, and chairside molded were manufactured. All restorations were cemented onto sintered zirconia abutment dies and adhered with zinc-oxide non-eugenol temporary cement. Artificial aging was conducted by thermocycling for 800 cycles to simulate 1 month of clinical use. All specimens were submerged in 2% (w/w) methylene blue for 24 hours at 37°C, sectioned, and analyzed digitally for the distance of dye penetration through image analysis. The data were analyzed using the Kruskal-Wallis test with Dunn-Bonferroni post-hoc. Significant differences in dye penetration depth were observed between all groups except milled vs chairside molded. Light microscopy revealed differences in mean cement thickness for 3D printed, milled, and chairside molded of 83.6 µm (1σ = 31.9 µm), 149.1 µm (1σ = 88.7 µm) and 137.9 µm (1σ = 67.2 µm) respectively. Conclusion: 3D printed provisional restorations were found to have the least amount of microleakage compared to milled and chairside molded provisional restorations.

Microleakage of chairside moulded, 3D-printed and milled provisional restorations using a curve-fit approach

Abstract The purpose of this study was to evaluate and measure the microleakage inhibiting quality of provisional restorations manufactured using computer-aided manufacturing, 3D printing, and chairside molded provisional restorative materials. Fifteen provisional restorations each from 3D printed, milled, and chairside molded were manufactured. All restorations were cemented onto sintered zirconia abutment dies and adhered with zinc-oxide non-eugenol temporary cement. Artificial aging was conducted by thermocycling for 800 cycles to simulate 1 month of clinical use. All specimens were submerged in 2% (w/w) methylene blue for 24 hours at 37°C, sectioned, and analyzed digitally for the distance of dye penetration through image analysis. The data were analyzed using the Kruskal-Wallis test with Dunn-Bonferroni post-hoc. Significant differences in dye penetration depth were observed between all groups except milled vs chairside molded. Light microscopy revealed differences in mean cement thickness for 3D printed, milled, and chairside molded of 83.6 µm (1σ = 31.9 µm), 149.1 µm (1σ = 88.7 µm) and 137.9 µm (1σ = 67.2 µm) respectively. Conclusion: 3D printed provisional restorations were found to have the least amount of microleakage compared to milled and chairside molded provisional restorations.

Resumo O objetivo deste estudo foi avaliar e medir a qualidade de inibição de microinfiltração de restaurações provisórias fabricadas usando manufatura assistida por computador, impressão 3D e materiais de restauração provisória moldados no consultório. Foram fabricadas 15 restaurações provisórias impressas em 3D, fresadas e moldadas em consultório. Todas as restaurações foram cimentadas em matrizes de pilar de zircônia sinterizada e aderidas com cimento temporário de óxido de zinco sem eugenol. O envelhecimento artificial foi conduzido por termociclagem por 800 ciclos para simular 1 mês de uso clínico. Todos os espécimes foram submersos em azul de metileno a 2% (p/p) por 24 horas a 37°C, seccionados e analisados digitalmente quanto à distância de penetração do corante por meio de análise de imagem. Os dados foram analisados usando o teste de Kruskal-Wallis com post-hoc de Dunn-Bonferroni. Foram observadas diferenças significativas na profundidade de penetração do corante entre todos os grupos, exceto entre fresado e moldado na cadeira. A microscopia óptica revelou diferenças na espessura média do cimento para as restaurações impressas em 3D, fresadas e moldadas em cadeira de 83,6 µm (1σ = 31,9 µm), 149,1 µm (1σ = 88,7 µm) e 137,9 µm (1σ = 67,2 µm), respectivamente. Conclusão: As restaurações provisórias impressas em 3D apresentaram a menor quantidade de microinfiltração em comparação com as restaurações provisórias fresadas e moldadas no consultório.

Adhesion of Denture Characterizing Composites to Heat-Cured, CAD/CAM and 3D Printed Denture Base Resins.

PURPOSE: To measure the adhesion of the denture characterizing composite to heat-cured, CAD/CAM and 3D printed denture base resins. METHODS AND MATERIALS: Two different denture characterizing composites with different viscosities (SR Nexco; high viscosity (SR) and Kulzer Cre-active; low viscosity (K)) and three denture base resins (Heat cure, CAD-milled and 3D printed) were investigated. 60 beams (25 × 4 × 3 mm) were fabricated for each denture base resin; 30 were bonded to SR and 30 to K to form a beam 50 × 4 × 3 mm. These were further divided (n = 10/group) to simulate the effects of 0, 6, and 12 months intraorally via thermocycling. The beams were subjected to a 4-point bend test using the chevron-notched beam method. Fracture toughness K1C (MPa ·m1/2 ) and flexural bond strength (MPa) were calculated. All specimens were analyzed for the mode of failure under the light microscope and selected specimens under scanning electron microscope. Results were statistically analyzed using ANOVA (SPSS Ver 25). RESULTS: The mean K1C was highest for the SR composite bonded to the heat-cured denture resin group (0.28 ± 0.11), followed by CAD/CAM (0.18 ± 0.04) and 3D printed groups (0.23 ± 0.16). Differences were not statistically significant (p = 0.268). Within each group, aging showed no statistical significance between the mean K1C and flexural bond strength (p = 0.209). The mean K1C for the K composites bonded to the three different denture bases were significantly lower compared to the SR group (p < 0.001). The mean K1C for the heat-cured denture resin group was (0.21 ± 0.1), followed by CAD/CAM (0.13 ± 0.04) and 3D printed groups (0.03 ± 0.02). Within each of the K group, aging showed a statistical significance for both the mean K1C and flexural bond strength (p = 0.002). CONCLUSION: The high viscosity SR showed significantly higher K1C and flexural bond strength to the lower viscosity K when bonded to heat-cured, CAD-milled and 3D printed denture base resins. Heat-cured denture base resins produced the highest K1C and flexural bond strength when bonded to two different types of characterizing composites.

Bond Strength of Denture Teeth to Heat-Cured, CAD/CAM and 3D Printed Denture Acrylics.

PURPOSE: To establish the fracture toughness (K1C ) and flexural bond strength of commercially available denture teeth to heat cured, CAD/CAM and 3D printed denture-based resins (DBRs). MATERIALS AND METHODS: Three types of DBRs (Heat cure, CAD-milled and 3D printed) and four different types of commercial denture teeth (Unfilled PMMA, double cross-linked PMMA, PMMA with nanofillers and 3D printed resin teeth) were investigated. DBR and epoxy embedded denture teeth (n = 30 per group) specimen beams (25 × 4 × 3 mm) were fabricated. The testing ends of all the specimens were surface treated, bonded and processed according to manufacturer's instructions. Twenty specimens were thermal cycled to simulate the effects of 6 and 12 months intraorally. A 4-point bend test, using the chevron-notched beam method was done and K1C (MPa ·m1/2 ) and flexure bond strength (MPa) were calculated. All specimens were analysed for the mode of failure under the light microscope and selected specimens under scanning electron microscope. Results were statistically analysed using ANOVA (SPSS Ver 24). RESULTS: The mean K1C was the highest for the teeth bonded to the heat-cured DBR group (1.09 ± 0.24), followed by CAD/CAM (0.43 ± 0.05) and 3D printed groups (0.17 ± 0.01). Differences were statistically significant (p < 0.01). Within each group, aging showed statistically significantly lower values but no statistical significance between the mean K1C and flexural bond strength (p = 0.36). The dominant mode of failure was cohesive in the CAD/CAM groups and adhesive in the heat-cured and 3D printed groups. CONCLUSION: Teeth bonded to heat-cured DBRs produced the highest K1C .The bond strength decreased significantly with aging. Teeth bonded to CAD/CAM and 3D printed DBRs showed significantly lower bond strength, with no significant influence of aging.