Clinical Research And Literature Review Of Orthodontic Cases With Miniscrews

Objective:To evaluate the effectiveness of microscrew anchorage for intrusion of molar and anterior teeth.Materials and Methods:The study was comprised of 11 patients with excessive growth teeth from August 2007 to March 2009.Cephalometric radiographs and model were taken immediately before intrusion.All the patients was willingly to use microscrew anchorage for intrusion.They aged from 15 to 46 years,mean 28.4 years. Localization of the point of insertion.Self-drilling microscrew implants were inserted into the alveolar process(both buccally and palatally between the roots of the excessive growth teeth).A force of 50～200g was applied to the microscrews on one or each side to intrude the excessive growth teethin with partial or full-mouth fixed appliances. Lateral cephalograms of all 11 patients were taken preintrusion and immediately after completion of the intrusion.To assess dental changes in the vertical and horizontal directions,landmark images of the palatal plane were used as references to establish a coordinate system.Four linear parameters were measured(U1-PP,U6-PP,U1-Ypp, U6-Ypp).The statistical analysis was performed with SPSS 10.0(SPSS,Chicago,IL). The mean difference of each variable was examined with paired Student's t-tests.All variables were measured at two different times by the same investigator to calculate the error of the method. Results:The results showed that the excessive growth teeth in 11 patients were all corrected successfully.The treatment period of intrusion was from 3 to 8 months(mean 5.9 months).The molar and anterior teeth were intruded for an average of 2.7 mm (P＜.001) and 2.3 mm(P＜.001),respectively.The apical root resorption was not clinically significant and the bone level was unchanged.3 microscrews were failure during treatment due to inflammation,whereas those microscrews were stable when insert again after an appropriate antibiotic treatment.Conclusion:It was applicable to use the microscrew as anchorage in partial or full-mouth fixed appliances to intrude excessive growth teeth.The provided absolute anchorage eliminates undesirable effects on the teeth that otherwise would have been normally used as anchorage.Miniscrew anchorage has the advantages of being a simpler procedure,being minimally invasive,and requiring minimal patient cooperation.