Fracture resistance and mode of failure of CAD/CAM-fabricated monoblock endocrowns varies widely between materials. Clinicians should be cautious with material selection for endocrown restorations. SUMMARYThis study assessed marginal leakage and fracture resistance of computer-aided design/ computer-aided manufacturing (CAD/CAM) fabricated ceramic crowns with intracoronal extensions into the pulp chambers of endodontically treated teeth (endocrowns) using either feldspathic porcelain (CEREC Blocks [CB], Sirona Dental Systems GmbH, Bensheim, Germany), lithium disilicate (e.max [EX], Ivoclar Vivadent, Schaan, Liechtenstein), or resin nanoceramic (Lava Ultimate [LU], 3M ESPE, St Paul, MN, USA).). Thirty extracted human permanent maxillary molars were endodontically treated. Standardized preparations were done with 2-mm intracoronal extensions of the endocrowns into the pulp chamber. Teeth were divided into three groups (n=10); each group was restored with standardized CAD/CAM fabricated endocrowns using one of the three tested materials. After cementation with resin cement, specimens were stored in distilled water at 378C for one week, subjected to thermocycling, and immersed in a 5% methylene-blue dye solution for 24 hours. A compressive load was applied at 35 degrees to long axis of the teeth using a universal testing machine until failure. Failure load was recorded, and specimens were examined under a stereomicroscope for modes of failure and microleakage. Results were analyzed using one-way analysis of variance and Bonferroni post hoc multiple comparison tests (a=0.05). LU showed significantly (p,0.05) higher fracture resistance and more favorable fracture mode (ie, fracture of the endocrown without fracture of tooth) as well as higher dye penetration than CB and EX. In conclusion, although using resin

The purpose of this investigation was to evaluate the immediate effects of calibration on inter-rater agreement to a gold standard (GS) and to determine whether the effects can be sustained over a ten-week period. Valid criteria for a Class II amalgam preparation, a three-point rating scale, and a grade form were developed. Three tests were administered: prior to calibration training, immediately following training, and ten weeks later. Each test consisted of faculty independently evaluating ten prepared teeth. Agreement with GS scores for most of the grading criteria improved as a result of training and did not deteriorate over time. The overall percent agreement was 54.5, 66.9, and 64.6 percent across test periods. The most impressive gains in agreement occurred when the criteria evaluated had a GS score of either "standard not met" or "ideal." There was very little gain when the gold standard score was "acceptable." It is concluded that, with training, inter-rater agreement with a gold standard can improve and such improvement is reasonably resistant to deterioration after ten weeks. Nevertheless, future training ought to consider the use of a mastery approach in calibration training to ensure that a satisfactory degree of agreement with the GS is obtained.

The morphologic characteristics of the caries-affected dentin/interface suggest an increase in the exposed collagen zone and a decrease in the quality of the adhesive infiltration when compared with noncarious dentin. The evidence suggests that dentin substrate characteristics have a significant effect on the dentin/adhesive interface structure.

Although moisture may not adversely affect the dimensional accuracy of either PE or hydrophilic PVS material, the evidence suggests that PE material is more likely to produce impressions with superior detail reproduction in the presence of moisture.

The responsibility of RDP design appeared to be largely delegated to dental technicians. Importance of tooth modifications seemed to be undervalued and not completed prior to framework fabrication.