Evaluation of the success rate of single- and dual-thread orthodontic miniscrews inserted in the palatal side of the maxillary tuberosity.

BACKGROUND: Recent studies have reported that the placement of miniscrews for orthodontic anchorage in maxillary tuberosity is anatomically safe and can aid in achieving efficient tooth movement mechanically. However, the success rate of miniscrews placed on the palatal aspect of the maxillary tuberosity has not yet been elucidated. This study aimed to evaluate the success rate of single- and dual-thread miniscrews inserted in the palatal aspect of the maxillary tuberosity. METHODS: A total of 101 miniscrews (17 single-thread miniscrews: diameter 2.0 mm, length 10 mm; 84 dual-thread miniscrews: diameter 2.0 mm, length 12 mm) placed in 61 patients (6 males, 55 females; mean age = 30.9 ± 8.66 years) were retrospectively examined. Miniscrews that could be maintained for orthodontic anchorage for more than 6 months were considered successful. The direction of placement, bone-miniscrew contact (BMSC) rate, and survival of miniscrews were measured using cone-beam computed tomography. RESULTS: The overall success rate of single-thread miniscrews was 82.4% and that of dual-thread miniscrews was 94.0%. There was no significant difference in the overall clinical success rate between the two designs. Sex, mandibular plane angle, and malocclusion type did not significantly affect the success rate in both groups. CONCLUSIONS: Both single- and dual-thread miniscrews placed on the palatal aspect of the maxillary tuberosity showed high success and BMSC rates. However, there were no significant differences in the overall success rate and BMSC rate between the two miniscrew designs.

Role of interleukin-6 in orthodontically induced inflammatory root resorption in humans.

OBJECTIVE: To determine the interleukin (IL)-6 levels in gingival crevicular fluid (GCF) of patients with severe root resorption after orthodontic treatment and investigate the effects of different static compressive forces (CFs) on IL-6 production by human periodontal ligament (hPDL) cells and the influence of IL-6 on osteoclastic activation from human osteoclastic precursor (hOCP) cells in vitro. METHODS: IL-6 levels in GCF samples collected from 20 patients (15 and 5 subjects without and with radiographic evidence of severe root resorption, respectively) who had undergone orthodontic treatment were measured by ELISA. The levels of IL-6 mRNA in hPDL cells and IL-6 protein in conditioned medium after the application of different uniform CFs (0, 1.0, 2.0, or 4.0 g/cm(2) for up to 72 h) were measured by real-time PCR and ELISA, respectively. Finally, the influence of IL-6 on mature osteoclasts was investigated by using hOCP cells on dentin slices in a pit-formation assay. RESULTS: Clinically, the IL-6 levels were significantly higher in the resorption group than in the control group. In vitro, IL-6 mRNA expression significantly increased with increasing CF. IL-6 protein secretion also increased in a time- and magnitude-dependent manner. Resorbed areas on dentin slices were significantly greater in the recombinant human IL-6-treated group and group cultured in hPDL cell-conditioned medium with CF application (4.0 g/cm(2)) than in the group cultured in hPDL cell-conditioned medium without CF application. CONCLUSIONS: IL-6 may play an important role in inducing or facilitating orthodontically induced inflammatory root resorption.