Chris Chang1, Sean S Y Liu2, W Eugene Roberts3. 1. a Private Practice, Beethoven Orthodontic Center, Hsinchu City, Taiwan. 2. b Assistant Professor, Department of Orthodontics and Orofacial Genetics, Indiana University School of Dentistry, Indianapolis, Ind. 3. c Professor Emeritus of Orthodontics and Adjunct Professor of Mechanical Engineering, Indiana University and Purdue University, Indianapolis, Ind.
Abstract
OBJECTIVE: To compare the initial failure rate (≤4 months) for extra-alveolar mandibular buccal shelf (MBS) miniscrews placed in movable mucosa (MM) or attached gingiva (AG). MATERIALS AND METHODS: A total of 1680 consecutive stainless steel (SS) 2 × 12-mm MBS miniscrews were placed in 840 patients (405 males and 435 females; mean age, 16 ± 5 years). All screws were placed lateral to the alveolar process and buccal to the lower first and second molar roots. The screw heads were at least 5 mm superior to the soft tissue. Loads from 8 oz-14 oz (227 g-397 g, 231-405 cN) were used to retract the mandibular buccal segments for at least 4 months. RESULTS: Overall, 121 miniscrews out of 1680 (7.2%) failed: 7.31% were in MM and 6.85% were in AG (statistically insignificant difference). Failures were unilateral in 89 patients and bilateral in 16. Left side (9.29%) failures was significantly greater (P < .001) compared with those on the right (5.12%). Average age for failure patients was 14 ± 3 years. CONCLUSION: MBS miniscrews were highly successful (approximately 93%), but there was no significant difference between placement in MM or AG. Failures were more common on the patient's left side and in younger adolescent patients. Having 16 patients with bilateral failures suggests that a small fraction of patients (1.9%) are predisposed to failure with this method.
OBJECTIVE: To compare the initial failure rate (≤4 months) for extra-alveolar mandibular buccal shelf (MBS) miniscrews placed in movable mucosa (MM) or attached gingiva (AG). MATERIALS AND METHODS: A total of 1680 consecutive stainless steel (SS) 2 × 12-mm MBS miniscrews were placed in 840 patients (405 males and 435 females; mean age, 16 ± 5 years). All screws were placed lateral to the alveolar process and buccal to the lower first and second molar roots. The screw heads were at least 5 mm superior to the soft tissue. Loads from 8 oz-14 oz (227 g-397 g, 231-405 cN) were used to retract the mandibular buccal segments for at least 4 months. RESULTS: Overall, 121 miniscrews out of 1680 (7.2%) failed: 7.31% were in MM and 6.85% were in AG (statistically insignificant difference). Failures were unilateral in 89 patients and bilateral in 16. Left side (9.29%) failures was significantly greater (P < .001) compared with those on the right (5.12%). Average age for failure patients was 14 ± 3 years. CONCLUSION:MBS miniscrews were highly successful (approximately 93%), but there was no significant difference between placement in MM or AG. Failures were more common on the patient's left side and in younger adolescent patients. Having 16 patients with bilateral failures suggests that a small fraction of patients (1.9%) are predisposed to failure with this method.
Authors: Muhammad Azeem; Arfan Ul Haq; Zubair Hassan Awaisi; Muhammad Mudassar Saleem; Muhammad Waheed Tahir; Ahmad Liaquat Journal: Dental Press J Orthod Date: 2019-11-11