PurposeTo 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 MethodsThree 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).ResultsThe 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.ConclusionTeeth 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.

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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.

AimTo record the pulp temperature at different tooth sites during fabrication of two different temporary crown systems.MethodologyTwo temporary crown systems were investigated; a conventional direct fabricated and a preformed thermoplastic resin system. Extracted caries-free human teeth (incisor, premolar and molar) were prepared for full coverage ceramic restoration with roots sectioned below the cemento-enamel junction. Thermocouple wires were secured at the surface of crown material, the cut dentine and inside the pulp cavity. Provisional crowns (n = 10/group) from each system were formed prior to placement in a water bath of 37 °C to simulate pulpal temperature. Temperatures were recorded using a K-type thermocouple data logger to collect the mean and peak temperature during crown fabrication. Statistical analysis was carried out on all tested groups and heat flow was calculated.ResultsFor direct fabricated crowns, the mean rise in pulpal temperature recorded was 0.1 °C with the mean temperature range of 37.3 °C–37.8 °C. For the preformed thermoplastic crowns, the mean rise in pulpal temperature recorded was 37.3 °C–45.1 °C. The increase in temperature was significantly higher (6.5 °C for the incisor group, 7.5 °C for the premolar group, and 6.7 °C for the molar group). For both crown systems, the temperature difference between the three different sites; pulp, crown and tooth surface showed a statistical difference (P < 0.01).ConclusionsThe direct fabrication system showed minimal temperature changes within the teeth, while the preformed thermoplastic fabrication system showed larger temperature change in the teeth.