Use of Digital Technology to Improve Objective and Reliable Assessment in Dental Student Simulation Laboratories.

The aim of this study was to assess inter-and intra-grader agreement with the use of digital scanning and a tooth preparation assessment software program in comparison to the current traditional visual grading method in a dental student simulation laboratory. Students' typodont teeth preparations from previous practical examinations were used (cast crown n=50; cast fixed partial denture abutments n=50). Five preclinical instructors received calibration training and evaluated each of the preparations by the traditional visual grading method using a rubric. The same preparations were assessed by the same instructors using a tooth preparation assessment software program (PrepCheck, Sirona). The results showed that intra-grader agreement was significantly higher when grades were determined by PrepCheck compared to the traditional visual grading method. The traditional method was associated with significantly greater inter-grader disagreement in comparison to grading using PrepCheck (p<0.05). When the average final grade for students' crown preparations by each grader was compared for the traditional method and PrepCheck, significant differences were found for all graders (p<0.001). In this study, the use of the PrepCheck software program greatly improved intra-and inter-grader agreement during grading in a student simulation laboratory. Digital technology may improve the objectivity and reliability of assessments by preclinical evaluators.

Osteogenic potential for replacing cells in rat cranial defects implanted with a DNA/protamine complex paste.

Osteoinductive scaffolds are required for bone tissue engineering. The aim of the present study was to assess the osteoinductive capacity of deoxyribonucleic acid (DNA)/protamine complexes in a rat model of critical-size calvarial defects. In addition, we investigated whether cultured mesenchymal-like cells (DP-cells) outgrown from DNA/protamine complex engrafted defects could differentiate to become osteogenic cells in vitro. DNA/protamine complexes were prepared by reactions between DNA and protamine sulfate solutions with stirring. Critical-sized (8mm) calvarial defects were created in the central parietal bones of adult rats. Defects were either left empty or treated with DNA/protamine complex scaffolds. Subsequently, micro-computed tomography (micro-CT), histological, and immunohistochemical analyses were performed. Micro-CT and histological assays showed that DNA/protamine complex engrafted defects had enhanced bone regeneration. DP-cells were expanded from explants of DNA/protamine complex engrafted defects using an explant outgrowth culture system. Osteogenesis-related factors were assessed in DP-cells after treatment with an osteoblast-inducing reagent (OIR). After 3months, nearly complete healing was observed for DNA/protamine complex engrafted calvarial defects. Increased alkaline phosphatase (ALP) activity and Alizarin red staining were found for cultured DP-cells. These cells had high expression levels of osteogenic genes, including those for RUNX-2, ALP, osteopontin, and osteocalcin. These results indicated that DNA/protamine complexes could facilitate bone regeneration in calvarial defects. Moreover, in vitro osteogenic induction experiments showed that DP-cells outgrown from DNA/protamine engrafted defects had an osteogenic potential. Based on these results, we suggest that DNA/protamine complexes may recruit osteocompetent cells in these defects, where they differentiate to osteogenic cells.

Evaluation of bone formation guided by DNA/protamine complex with FGF-2 in an adult rat calvarial defect model.

DNA/protamine complex paste (D/P) and D/P complex paste with Fibroblast Growth Factor-2 (FGF-2) (D/P-FGF) were prepared to investigate their new bone formation abilities using an ∼40-week-old rat calvarial defect model. It was found that D/P could release FGF-2 proportionally in an in vitro experiment with an enzyme-linked immunosorbent assay. It was also found that aging adversely affected self-bone healing of rats by comparison with the results in a previous study using 10-week-old rats. Microcomputed tomography and histopathological examinations showed that new bone formation abilities of D/P and D/P-FGF were superior to that of the control (sham operation). Control, D/P and D/P-FGF showed newly formed bone areas of 6.7, 58.3, and 67.0%, respectively, 3 months after the operation. Moreover, it was found that FGF-2 could support the osteoanagenesis ability of D/P. It was considered that FGF-2 could play an important role in new bone formation at early stages because it induced the genes such as collagen I, CBFA, OSX, and OPN, which are initiated first in the process of osteogenesis. Therefore, D/P-FGF will be a useful injectable biomaterial with biodegradable properties for the repair of bone defects in the elderly.