CBCT For Assessment Of Micro-implant Anchorage For Excessive Growth Teeth

Objective:The purpose of this study was to use cone-beam computed tomography (CBCT) to evaluate the effectiveness and root resorption of micro-implant anchorage for intrusion of molar and anterior teeth.Methods:The study was comprised of 6 patients with excessive growth teeth from November 2009 to March 2010. CBCT and photos were taken immediately before and after intrusion. Three-dimensional CBCT images, measuring 9 and 12 in, were taken with a CBCT machine (NewTom 3G, Italy). All the patients was willingly to use micro-implant anchorage for intrusion. Landmark coordinates and linear and angular measurements were obtained with Surgicase software. Four linear parameters were measured (M-FH, MB1-FH, MB2-FH, MP-FH, LI-MP), one angular parameter was measured (IR-MP). The statistical analysis was performed with SPSS 10.0 (SPSS, Chicago, IL). Root resorption were obtained with NNT software.Results:The results showed that 12 excessive growth teeth were all corrected successfully. The treatment period of intrusion was from 3 to 5 months. The molar and anterior teeth were intruded for an average of 1.4 mm(M-FH) (P>0.05) and 3.1 mm(LI-MP)(P<.001), and the angular measurement was changed for an average of 9.0°(p<0.01). The root resorption was clinically significant, especially in the lower anterior teeth. Ten root resorption were unchanged, fifteen root resorption were changed by 1 level,and one root resorption was changed by 2 level.Conclusion:CBCT can measure every tooth and every tooth cusp precisely,also it can discover the root resorption easily. It was applicable to use the micro-implant as anchorage to intrude excessive growth anterior teeth, but it may induce root resorption.CBCT seems to be superior to conventional CT and cephalograms for orthodontic cases.