A 3-Year Clinical Evaluation of Endodontically Treated Posterior Teeth Restored with Resin Nanoceramic Computer-Aided Design/Computer-Aided Manufacture (CAD/CAM)-Fabricated Partial Crowns.

BACKGROUND We aimed to investigate the clinical effects of resin nanoceramic (RNC) computer-aided design/computer-aided manufacture (CAD/CAM) partial crowns on posterior teeth after root canal treatment over a 3-year period. MATERIAL AND METHODS A total of 132 posterior teeth restored with CAD/CAM partial crowns were placed in 128 patients. The observation group (n=66) was restored with RNC restorations, while the control group received lithium disilicate-based glass ceramic (LDGC) CAD restorations. Using Federation dentaire internationale (FDI) World Dental Federation clinical criteria, 2 calibrated evaluators examined the performance of the restorations at baseline, 6, 12, 18, 24, and 36 months. The Kaplan-Meier method and the log-rank test were adopted to analyze the survival rate. The influence of potential risk factors on the main pattern of failure was studied by univariate Cox regression analysis (alpha=0.05). RESULTS At the 3-year followup, the survival rate of the partial crowns was 83.1% in the RNC group, and 93.5% in the LDGC group (P=0.061). Failures were caused by debonding (66.7%), restoration fracture (26.6%), and tooth fracture (6.7%). No significant differences were found between the 2 materials at 36 months, except for the parameters of "surface luster" (P=0.002) and "occlusal contour and wear" (P=0.009). The RNC group was significantly more likely to debond than the LDGC group (hazard ratio=9.22 [1.17,72.74], P=0.01). CONCLUSIONS RNC CAD/CAM-fabricated partial crowns are a potential clinical alternative for endodontically treated posterior teeth, with a survival rate of 83.1% at the 3-year followup. The main pattern of failure was debonding, which might be influenced by surface pretreatment of the RNC material.

Nanopatterned Polymer Surface Modulates Twist Polymorphism in a Single Amyloid Fibril.

The periodic twist behaviors of amyloid fibrils initiated and formed on block copolymer films with nanoscale features are studied. The discovery of twist variations even in a single amyloid fibril is reported: the fibril can vary its twist extents in response to the underlying nanopatterned surfaces by keeping its neighboring crossover sections right above the periodic nanodomains and tuning the distance between neighboring crossover sections based on either the periodic nanodomain distance or the fibril contour direction. This nanopattern-induced twist polymorphism arises from the fibril's two edges, exhibiting different hydrophobic interactions with the periodic nanodomains, as demonstrated by simulation studies. This work contributes to the understanding of surface effects on twist polymorphism in amyloid fibril structures that may be important to fibril polymorphism in amyloid pathologies and bioapplications of amyloid fibrils.