Subject: A systematic review of patient, screw, surgery, and loading-related effects on the stability of miniscrews was carried out. Materials and Methods: Investigations published until September 2007 and designated as human clinical trials were considered if at least 30 miniscrews were used. Parameters under review were patient gender and age, location and method of screw insertion, screw length and diameter, time until, duration and amount of loading. Results: Fourteen clinical trials covered 452 patients and 1519 screws.
The mean overall success rate was 83.8 7.4%. Patient gender showed no significant differences. In terms of age 1 among 5 studies showed a significant difference (P < .05) in patients aged >30 years. Screw diameters of 1 - 1.1 mm yielded significantly lower success than those of 1.5 - 2.3 mm. One study reported significantly lower success for 6 mm vs. 8 mm long miniscrews (72% vs. 90%). Screw insertion with or without surgical flap showed contradictory results between publications. Three studies showed significantly higher success rates for maxillary than mandibular screws. Loading and healing period played no significant role in the miniscrews' success rates. Conclusions: All 14 papers described success rates as sufficient for orthodontic treatment. Implantation protocols varied markedly and may require further investigation. Screws under 8 mm length and 1.2 mm diameter should be avoided. Immediate or early loading up to 200 cN was adequate and showed no significant influence on screw stability.