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Objectives To determine if the depth of corticotomy done with the piezoelectric knife could play a role in the intensity of the regional acceleratory phenomenon (RAP). Materials and Methods Eighteen Sprague-Dawley rats were divided into two groups: untreated (3 rats) and treatment (15 rats). In the treatment group, a split-model design was used. The right tibia received transcortical (deep) penetrations with the piezoelectric knife, while intracortical (shallow) penetrations were performed on the left tibia of the same animal. The rats were euthanized at day 1, 3, 7, 14, and 28. Cone-beam computed tomography scans were taken for each sample and then assessed by histological analysis. Results Higher amounts of osteoclastic activity and new collagen formation were observed in the deep penetration group when compared with the shallow penetration group. The former peaked at day 14 for both groups (1.53% ± 0.01% vs 0.03% ± 0.0004%, respectively), and the latter peaked at day 28 (0.65 × 106 ± 0.01 vs 0.08 × 106 ± 0.0008, respectively). Conclusions Within the limitations of this study, it appears that the intensity of the RAP in the rat is corticotomy depth dependent. This is to be kept in mind when decorticating the bone during surgically facilitated orthodontic procedures.

although in scant amounts with minimal yield of specimen for biopsy [18]. Spontaneous resolution has been reported [12,17], however, curettage eliciting fresh blood and subsequent clot formation will yield predictable consolidation. Within six to twelve months after surgical exploration, remineralization of the lesion and normal radiographic appearance will be observed [3]. Case PresentationA 14-year-old healthy female presented for a consult due to a random radiographic finding in the right inferior portion of the anterior mandible on a panoramic radiograph taken as part of her orthodontic treatment. Patient reported no symptoms and denied any trauma to the mandible.Upon clinical examination: no extra oral swelling or lymphadenopathy found, intra oral exam revealed no fluctuation, no buccal or lingual cortical expansion ( Figures 1A and 1B), all mandibular canines, lateral and central incisors showed normal response to thermal (cold) test and diagnosed vital with no evidence of mobility and had normal probing depths. Figure 2 from a pre-operative CBCT taken on 2014 there is a well-defined, round, lightly corticated mixed-density lesion in the right inferior portion of the anterior mandible. The right border of the lesion lies immediately apical to tooth #27 and the left border just crosses the midline. It slightly thins but does not expand not perforate the buccal or lingual cortices. It has no effect on the nearby dentition, abutting the apical lamina dura of tooth #27 without perforation. The internal structure of the lesion is largely hypodense with a mixed, cloudy hyperdensity in the inferior quarter of the lesion. As demonstrated in