The dentofacial effects of maxillary incisor intrusion with micro-implant anchorage

The aim of this study was to evaluate the skeletal, dentoalveolar and soft tissue changes after maxillary incisor intrusion while using a mini arch wire and micro-implants as anchorage.35 patients with deepbite due to excessive maxillary incisor eruption were included in this study. The subjects had skeletal and dental Class I or mild Class II malocclusion, mild space deficiency in the maxillary arch, more than 4 mm of deep overbite and optimum or high mandibular plane angle prior to the study.The treatment group included 20 patients (10 females, 10 males) with mean chronological ages of 13,08+1.15 years. The control group included 15 patients (5 females, 10 males) with mean chronological ages of 12,07+1.3 years. Skeletal ages at the begining of the treatment were 13,00+1,18 years for the treatment group and 12,34+0.95 years for the control group.For the maxillary incisor intrusion, orthodontic micro-implants were inserted in the maxillary dentoalveolar area between canine and lateral incisor roots. Closed coil springs (each applied 50 gr of force and as a total 100 gr of force was delivered to four upper incisors) were activated by pulling between the heads of the micro-implants and the helixes which were bent nearby the lateral braces on the mini arch wire. The intrusion was completed when proper upper lip to incisor relation and optimal overbite amount was obtained.Mean treatment time was 3,66 months and the control group was followed for 4 months.Lateral cephalometric films, periapical and panaromic radiographs and orthodontic models were taken before and after the study. The statistical analysis was made by using Repeated Measurements Factorial ANOVA with two factors as group and time. Duncan test was used for evaluation of the different groups.Significant intrusion and protrusion of the upper incisors, decrease in the occlusal plane, overbite and interincisal angle, increase in overjet, significant distortion of the laterals sideways and root resorption of these teeth were observed. Mandibular length was increased more in the treatment group. The upper lip length was decreased significantly in the treatment group.Key words: Maxillary incisor intrusion; Orthodontic micro-implants; Deep bite