Autotransplantation of immature third molars into edentulous and atrophied jaw sections.

The aim of the present study was to assess the results after transplantation of 85 immature third molars. Recipient site conditions varied and different surgical techniques were used. The long-term results after preparation of a new alveolus, splitting osteotomy of the alveolar process or use of free bone autografts were compared with the results after transplantation into a fresh extraction site (control group). Transplantations into prepared sockets showed equal results to the control group (94% respectively). Transplantations in connection with free bone autografts (84%) or after splitting osteotomy of the alveolar process (63%) showed poorer success rates, the differences between the latter and the control group being statistically significant. A possible correlation to revascularization disturbances of the pulp due to an insufficiency of the recipient site or to postoperative infection is suspected. The results show that transplantation of immature third molars is a safe, useful procedure when appropriate conditions of the recipient site are present. Where the alveolus is atrophic, a splitting osteotomy should be performed only in exceptional cases and preference should be given to alternative methods such as primary bone augmentation or bone-regenerative procedures.

Comparison of the number and diameter of dentinal tubules in human and bovine dentine by scanning electron microscopic investigation.

Detailed information on dentine structure is essential for interpreting data from investigations on dentine-adhesive materials. The purpose here was to compare the number and diameter of dentinal tubules at similarly prepared surfaces of bovine permanent central incisors and human deciduous and third molars. In bovine teeth, crowns and roots were used; in human samples only the crowns were investigated. Tubule density in the middle layer was higher in bovine root (BR) dentine (number of tubules per mm(2)+/-SD: 23, 760+/-2453) than in human deciduous (HD) (18,243+/-3845), human permanent (HP) (18,781+/-5855), and bovine coronal (BC) (17, 310+/-2140) dentine. The corresponding values for the deep layer were 23,738+/-4457 (BR), 24,162+/-5338 (HD), 21,343+/-7290 (HP), and 20,980+/-4198 (BC). No significant differences were found for the number of dentinal tubules in bovine coronal dentine compared to the dentine of human deciduous and permanent molars. The mean diameter of bovine dentinal tubules was slightly, but not significantly, higher than in human dentine (middle layer/deep layer+/-SD): BC, 2. 85 microm+/-0.18/3.50 microm+/-0.33; BR, 3.10 microm+/-0.33/3.23 microm+/-0.30; HD, 2.55 microm+/-0.16/2.82 microm+/-0.28; HP, 2.65 microm+/-0.19/2.90 microm+/-0.22. These findings demonstrate that corresponding coronal dentine layers of human deciduous and permanent molars, and of bovine central incisors, are not significantly different in their number of tubules per mm(2) and their tubule diameter, whereas tubule density in bovine root dentine is significantly higher. These results suggest that provided standardized preparations are used, bovine incisor crown dentine is a suitable substitute for human molar dentine in adhesion studies.

Bovine dentin as a substitute for human dentin in shear bond strength measurements.

PURPOSE: To evaluate the suitability of bovine coronal and root dentin as substitutes for human primary and permanent dentin in shear bond strength tests for dentin adhesives. MATERIALS AND METHODS: 30 bovine permanent central incisors, 30 human primary and 30 human third molars were cut mesiodistally. The pulpal and buccal dentin surfaces of the buccal cuts were milled with a bur to a thickness of 1.0 mm. A dentin adhesive and a hybrid composite were applied exactly according to the instructions given by the manufacturer on each buccal and pulpal surface, except in primary teeth where only the buccal surface was used. Shear bond strength was determined after 24 hours of storage in an aqueous solution. The results were statistically analyzed using the Wilcoxon- or the Mann-Whitney-U-test. RESULTS: There were no differences in shear bond strengths between human permanent dentin and bovine coronal dentin (13.3 +/- 6.1 vs. 15.2 +/- 7.6), and between each pulpal and buccal aspect. Significant differences were found between bovine root dentin and human primary dentin (17.4 +/- 8.3 vs. 7.7 +/- 5.0, P < 0.001). Significant differences were also found between bovine root dentin and human permanent dentin (17.4 +/- 8.3 vs. 13.3 +/- 6.1, P < 0.05), and bovine root and coronal dentin (17.4 +/- 8.3 vs. 15.2 +/- 7.6, P < 0.05). Furthermore, significant differences were recorded between human primary and human permanent dentin (7.7 +/- 5.0 vs. 13.3 +/- 6.1, P < 0.001) and bovine coronal dentin (7.7 +/- 5.0 vs. 15.2 +/- 7.6, P < 0.001).