Human Salivary Derived Esterases (HSDE) are part of the salivary group of enzymes which show strong degradative activity toward the breakdown of one of the most common monomers used in dental composites and adhesives, 2,2-[4(2-hydroxy 3-methacryloxypropoxy)-phenyl] propane (Bis-GMA), to form the degradation product 2,2-bis [4 (2,3-hydroxy-propoxy)phenyl] propane (Bis-HPPP). This study was aimed to evaluate the effects of HSDE on the biodegradation and fracture toughness of the adhesive resin-dentin interface. Adhesive resin (Scotchbond Multi Purposes), resin composite (Z250) and mini short-rod specimens, were either not incubated; or incubated in phosphate-buffered saline (PBS) or HSDE media for up to 180 days (37 degrees C, pH 7.0). The amount of Bis-HPPP was analyzed by high performance liquid chromatography and mini-SR specimens were tested for fracture toughness using universal testing machine following 30, 90, or 180-day incubation periods. Significantly higher amounts of Bis-HPPP were produced in HSDE than in PBS incubated specimens (p < 0.05). Non-incubated mini-SR specimens had the higher fracture-toughness values, while specimens incubated for 180-days in HSDE had the lowest fracture toughness (p < 0.05). This study suggests that biodegradation is an on-going clinically relevant process that progressively compromises the integrity of the critical resin restoration-adhesive interface, as well as the resin-composite component with time.

Objectives To evaluate the clinical performance and the effect of various patient and provider‐related factors on the longevity of chairside monolithic posterior lithium disilicate glass‐ceramic (LDGC) computer‐aided design (CAD)‐computer‐aided manufacturing (CAM) crowns provided by predoctoral students. Materials and Methods A sample of posterior LDGC CAD‐CAM crowns was evaluated. Crown preparations were milled chairside using the CEREC Omnicam system and cemented with Rely‐X Unicem or Calibra Universal resin cements. Clinical assessment of the crowns and supporting periodontal structures was performed using the modified California Dental Association (CDA) criteria. Intraoral photographs as well as radiographs were taken for further assessment by two evaluators. Kaplan‐Meier survival analysis was performed. Results A total of 40 crowns were inserted in 32 patients and evaluated for 4 years. Three complications were observed (two‐technical and one‐biological). No chipping or fracture of crowns was observed. No significant association was found between age, sex, periodontal condition, tooth type, tooth vitality, cement type, and longevity. The 4‐year cumulative survival and success rates were 95.0 and 92.3%, respectively. Conclusion Chairside LDGC CAD‐CAM crowns exhibited a high survival rate after 4 years in function and were shown to be a viable and reliable treatment option for posterior teeth. Clinical significance The high survival rate of chairside CAD‐CAM crowns observed in this study suggests the likelihood of predictable performance in the predoctoral setup.

Combining STL files with best-fit algorithms to appraise misfit is feasible using metrological software. The effect of misfit between the superstructures on its supporting implants up to ~230 μm on the long-term clinical outcomes appears to be minor, apart from a slightly higher risk of screw-related adverse events.

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