The regeneration capacity of osteoporotic bones is generally lower than that of normal bones. Nowadays, alendronate (AL) are orally administrated for osteoporosis due to the inhibition of bone resorption. However, systemic administration of AL is characterized by extremely low bioavailability and high toxicity. In this study, the amino-modified mesoporous bioactive glass scaffolds (N-MBGS) were fabricated by a simple powder processing technique as a novel drug-delivery system for AL. The effects of AL on the osteogenic differentiation of bone mesenchymal stem cells derived from ovariectomized rats (rBMSCs-OVX) were first estimated. The loading efficiency and release kinetics of AL on N-MBGS were investigated in vitro and the osteogenesis of AL-loaded N-MBGS in rat calvarial defect model was detected by micro-CT measurements and the histological assay. Our results revealed that proper concentration of AL significantly promoted osteogenic differentiation of rBMSCs-OVX. The amount and delivery rate of AL were greatly improved through amino modification. Additionally, scaffolds with AL showed better bone formation in vivo, especially for the N-MBGS group. Our results suggest that the novel amino-modified MBGS are promising drug-delivery system for osteoporotic bone defect repairing or regeneration. The experimental schematic of the novel amino-modified MBGS as a promising drug-delivery system for osteoporotic bone regeneration.

The purpose of the present study is to evaluate the fracture resistance of endodontically treated maxillary premolars restored using CAD/CAM onlays or crowns and luted with two types of resin cement. Forty all-ceramic crowns and twenty onlays were fabricated on maxillary premolars using the Cerec 3 system (n=10). The abutments were randomly subjected to two different procedures: Endodontic treatment was performed on forty teeth restored through a mesio-occlusal-distal (MOD) cavity preparation with composite resin fillings; twenty teeth without endodontic treatment served as control. In endodontically treated teeth restored using IPS e.max CAD crowns or onlays, the fracture loads were lower than those of the control. Endodontic treatment of teeth restored using CAD/ CAM crowns does not impair the fracture load but shows more severe fractures than teeth restored using CAD/CAM onlays. This suggests that a CAD/CAM onlay might be an effective method for the restoration of endodontically treated premolars with MOD cavity defect.

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IntroductionIn the light of the digital teaching, it is necessary that the effectiveness of a new digital real‐time evaluation system in the preclinical training of tooth preparation be evaluated.Materials and MethodsForty undergraduate dental students of the fourth year were randomly divided into the control group and the experimental group to complete the training task of tooth preparation for porcelain fused to metal (PFM) crown restoring the upper right central incisor. The control students received conventional training with instructor's guidance. The experimental students received training with the digital system without instructor's guidance. Every student exercised preparation in two resin incisors in 3 h training by respective training methods. A third incisor was prepared on a dental model in the simulated head phantom by each student as the test on the next day. All students' tooth preparations were scored by the same two experienced experts. The experimental students were asked to answer a questionnaire regarding their attitudes and opinions on the digital evaluation system in preclinical training.ResultsThere was no significant difference between the scores of the experimental group and the control group (p > .05). The students of two groups obtained the similar scores in the test (p > .05). Most of the students were supportive of the application of digital training system in the preclinical tooth preparation training course.ConclusionsThe digital real‐time evaluation system could provide effective training effects for the dental undergraduate students in the preclinical training of tooth preparation in fixed prosthodontics.