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The auxiliary device improved the mechanical retention force without the need to increase miniscrew length or diameter. This may enable the safe use of miniscrews in difficult areas.

Objectives To evaluate miniscrew stability and perform a histomorphometric analysis of the bone around the miniscrew under a load corresponding to orthopedic force. Materials and Methods Thirty-two miniscrews were implanted into eight rabbit tibias. Auxiliary group rabbits received auxiliary devices with miniscrews (n = 8, 28 days; n = 8, 56 days), and those in the nonauxiliary control group received miniscrews without auxiliary devices (n = 8, 28 days; n = 8, 56 days). Elastics were placed between miniscrews to apply a load of 5 N. Miniscrew stability was evaluated using a Periotest. Bone-to-implant contact (BIC) and spike implantation depth were measured histomorphologically. Results Periotest values in the auxiliary group were significantly lower than those in the nonauxiliary group at all time periods. There was no significant difference in BIC between the auxiliary and nonauxiliary groups at 28 or 56 days postimplantation. The implantation spike depth in the auxiliary group was significantly greater at 56 days compared to that at 28 days. Newly formed bone was observed around the spike of the auxiliary device at 56 days. Conclusions The results suggest that the use of miniscrews in conjunction with auxiliary devices provides stable skeletal anchorage, which may be useful in orthopedic treatments.

BackgroundWe describe the case of a 16-year-old female patient with micrognathia, temporomandibular joint (TMJ) ankylosis, and obstructive sleep apnea, who was treated with mandibular distraction osteogenesis (DO) combined with sliding genioplasty, using skeletal anchorage.Case presentationWe first performed interpositional arthroplasty, in which an interposition of fascia temporalis and surrounding fat tissue was inserted into the defect after bilateral condylectomy, increasing the maximum mouth opening from 5.0 to 32.0 mm. Subsequently, orthodontic treatment and advancement of the mandible were carried out by mandibular DO, using miniscrews and miniplates. Finally, sliding genioplasty was performed to bring the tip of the mandible forward. The total amount of mandibular advancement at the menton was 16.0 mm. An improved facial appearance and good occlusion were eventually achieved, and the apnea-hypopnea index decreased from 37.1 to 8.7. There was no obvious bone resorption or pain in the temporomandibular region, limited mouth opening (maximum mouth opening: 33.0 mm), myofascial pain or headache, downward rotation of the mandible, or lateral shift of mandibular position evident at 5 years and 6 months after mandibular DO.ConclusionMandibular DO using skeletal anchorage with intermaxillary elastics is useful for preventing extrusion of the upper and lower anterior teeth, thereby preventing rotation of the mandible. In addition, mandibular DO combined with sliding genioplasty is effective at improving both dentofacial deformities and impaired respiratory function.