The effect of the extent of surgical insult on orthodontic tooth movement.

OBJECTIVE: The primary objective of this study was to investigate how the extent of surgical insult affects the orthodontic tooth movement (OTM) and the alveolar bone modelling and remodelling in a rodent model.

MATERIAL AND METHODS: 15-week-old male Wistar rats were used in the research and they were randomly divided into three treatment groups: (1) OTM only (N = 8); (2) OTM + 2 alveolar decortication (AD) (less surgical insult) (N = 8); and (3) OTM + 4 AD (more surgical insult) (N = 8). A nickel-titanium spring delivering 5-8 g of force was used to protract the molar mesially using maxillary incisors as an anchorage. AD was done using a hand piece and a round bur, adjacent to the left first maxillary molar on the palatal alveolar bone. After 14 days of OTM Wistar rats were killed and microfocus computed tomography and histological analysis were performed.

RESULTS: The OTM + 4AD group presented with a significant increase (P < 0.05) in the rate of tooth movement when compared to OTM + 2AD group and OTM only group. In addition, the OTM + 4AD group had a significant decrease in bone volume and tissue density (P < 0.05) and a significant increase (P < 0.05) in the trabecular spacing and trabecular thickness when compared to OTM only. Histological quantification of tartrate-resistant acid phosphatase indicated a significant percent increase (P < 0.05) in OTM + 4AD group, when compared to OTM + 2AD and OTM only group.

RESULTS: Increased surgical insult increases the rate of OTM. Additionally, increased surgical insult decreases the bone volume and the tissue density.