A case of skeletal maxillary protrusion with high angle and gummy smile treated with anchor screws.

This report discusses a case of a 20 year and 7-month-old female patient with a skeletal maxillary protrusion with gummy smile, crowding, and high angle due to horizontal protrusion of the maxillary anterior teeth. The gummy smile in this case was improved by an upward movement of the occlusal plane associated with maxillary molar intrusion and sufficient lingual movement while performing maxillary anterior teeth intrusion. Following treatment, it was stable even after 8 years of retention. Thus, it is important to ascertain the cause of gummy smile, and establish whether it is due to the vertical maxillary excess in the maxillary anterior teeth, or the horizontal protrusion of the maxillary anterior teeth.

Alteration of tooth movement by reveromycin A in osteoprotegerin-deficient mice.

INTRODUCTION: Osteoprotegerin-deficient mice develop severe high-turnover osteoporosis with porous low-density trabecular bone from an age-related increase in osteoclast activity and are useful alveolar bone models of osteoporosis or frail periodontal tissue. Bisphosphonate (BP), a first-line drug for osteoporosis, is bone-avid, causing side effects such as brittle and fragile bones and jaw osteonecrosis after tooth extraction. In orthodontics, active movement is precisely controlled by temporarily suppressing and resuming movement. BP impedes such control because of its long half-life of several years in bone. Therefore, we investigated the novel osteoclast-specific inhibitor reveromycin A (RMA), which has a short half-life in bone. We hypothesized that tooth movement could be precisely controlled through temporary discontinuation and re-administration of RMA. METHODS: Osteoprotegerin-deficient mice and wild-type mice were developed as tooth movement models under constant orthodontic force. A constant orthodontic force of 10 g was induced using a nickel-titanium closed coil spring to move the maxillary first molar for 14 days. We administered BP (1.25 mg/kg) or RMA (1.0 mg/kg) continuously and then discontinued it to reveal how the subsequent movement of teeth and surrounding alveolar bone was affected. RESULTS: Continuous BP or RMA administration suppressed osteoclast activity and preserved alveolar bone around the roots, apparently normalizing bone metabolism. Tooth movement remained suppressed after BP discontinuation but resumed at a higher rate after discontinuation of RMA. CONCLUSIONS: RMA appears useful for controlling orthodontic tooth movement because it can be suppressed and resumed through administration and discontinuation, respectively.

Reveromycin A Administration Prevents Alveolar Bone Loss in Osteoprotegerin Knockout Mice with Periodontal Disease.

Chronic periodontal disease is characterized by alveolar bone loss and inflammatory changes. Reveromycin A (RMA) was recently developed and is a unique agent for inhibiting osteoclast activity. This study analysed the effects of RMA in an experimental mouse model of periodontitis involving osteoprotegerin (OPG)-knockout mice, specifically, whether it could control osteoclasts and reduce inflammation in periodontal tissue. We examined wild-type (WT) and OPG knockout mice (OPG KO) ligated with wire around contact points on the left first and second molars. RMA was administered twice a day to half of the mice. Using micro-computed tomography, we measured the volume of alveolar bone loss between the first and second molars, and also performed histological analysis. The OPG KO RMA+ group had significantly decreased osteoclast counts, alveolar bone loss, attachment loss, and inflammatory cytokine expression 8 weeks after ligation. Thus, RMA may reduce alveolar bone loss and inflamed periodontal tissues in patients with periodontitis.