Hypodontia and malformation are almost regular dental characteristics in patients suffering from ectodermal dysplasia. The distribution of absent teeth deviates remarkably from the general population. Treatment requires an interdisciplinary approach including orthodontics, prosthodontics and oral surgery.
Evidence for an acceleration of tooth movement in conjunction with the minimally invasive methods piezosurgical corticocision and osteoperforation of the alveolar process in humans is low.
Significant differences in the bone-to-screw contact between the two groups are no longer in evidence after three months due to new bone formation. The minor extent of bone remodeling in the not pre-drilled group rules out substantial bone damage, which might have occurred during screw placement as a result of "cracks" or an excessive increase in pressure along the interface. The similar rate of new bone formation in both groups speaks against a stimulating effect of pre-drilling. Despite the absence of quantitative differences, it remains unclear whether the mechanical quality of the newly-formed bone resembles that of preexisting bone. Our findings seem to be applicable to the human mandible, however, its thinner cortical layer means less screw-to-bone contact is likely. We must reckon with less bone contact in the maxilla for the same reason.
Objective
This study investigated the impact of a single piezocision in the maxillary alveolar process on the speed of tooth movement. The null hypothesis was that the speed of tooth movement will be equal with and without piezocision.
Methods
All maxillary molars on one side were moved against the combined incisors in 10 ten-week-old male Wistar rats. Under general anesthesia, a force of 25 cN was applied on either side using a Sentalloy closed coil spring. After placing the orthodontic appliance, vertical corticision was performed using a piezotome under local anesthesia, 2 mm mesial from the mesial root of the first molar on a randomly selected side; the other side served as the control. At the beginning of the treatment, and 2 and 4 weeks later, skull micro-computed tomography was performed. After image reconstruction, the distance between the mesial root of the first molar and the incisive canal, and the length of the mesial root of the first maxillary molar were measured. Moreover, the root resorption score was determined as described by Lu et al.
Results
Significantly higher speed of tooth movement was observed on the corticision side; thus, the null hypothesis was rejected. The loss of root length and root resorption score were significantly more pronounced after piezocision than before. A strong correlation was observed between the speed of tooth movement and root resorption on the surgical side, but the control side only showed a weak correlation.
Conclusions
Piezocision accelerates orthodontic tooth movement and causes increased root resorption.
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