Xifeng Wu

Piezoelectric ultrasonic bone surgery system in the extraction surgery of supernumerary teeth

INTRODUCTION The anterior maxillary region is a common site for supernumerary teeth. The aim of this study was to compare the use of piezoelectric ultrasonic bone surgery for the extraction of supernumerary teeth and the use of traditional method using bone chisels. METHODS 60 patients with supernumerary anterior maxillary teeth were considered in this study. They were randomly divided into two groups: 1) the control group, in which the supernumerary teeth were extracted using the traditional bone chisels method; 2) the experimental group, in which the supernumerary teeth were extracted using a piezoelectric ultrasonic bone surgery system. The operative time, amount of bleeding and post-operative pain were quantified and compared; in addition, the post-operative swelling was evaluated. RESULTS We observed a significant decrease (P < 0.01) in the amount of bleeding and post-operative pain in the experimental group respect to the control group; but the operative time was significantly increased (P < 0.01) with the use of piezoelectric system. In addition, post-operative swelling resolved more quickly in the experimental group. CONCLUSION Although the operative time for the extraction of the maxillary anterior supernumerary teeth was longer using the piezoelectric ultrasonic bone surgery system, the amount of bleeding and the post-operative complications were less, so this system could be considered an appropriate surgical method for the extraction of supernumerary teeth.

Comparative analysis of the stress distribution in five anatomical types of maxillary central incisor

BACKGROUND The maxillary central incisor is one of the most important anatomical indicators in esthetics, and stress distribution may vary among its five anatomical views (labial, palatal, mesial, distal, and incisal). OBJECTIVE To compare stress distribution among the five anatomical views of the maxillary central incisor under loading force at five angles and to observe and analyze the stress distribution in the dentin and periodontal ligament. METHODS We established three-dimensional finite element models of the five different views, which simulated the bite force with a static load force at 0∘, 30∘, 45∘, 60∘, and 90∘. The stress and displacement values for the cementoenamel junction (CEJ)-apical labial, palatal, mesial, and distal and the equivalent stress values on the periodontal ligament of the maxillary central incisor were calculated. RESULTS As the angle increased, the equivalent stress on the periodontal ligament, overall tooth displacement, equivalent stress, and displacement over the four views increased. The peaks of equivalent stress over the four views appeared within 0.8-17 mm below the CEJ, although all equivalent stress values decreased while approaching the peak. Within 1-19 mm below the CEJ, the equivalent stress over the M1 and P1 views of the maxillary central incisor decreased substantially. CONCLUSION The peaks of the equivalent stress over the M1 and P1 views of the maxillary central incisor and their stress distribution were lower than those of the other three types. Our findings provided theoretical data on the biomechanics of this esthetically important tooth, which may be useful during implantation of missing maxillary central incisors.