EVALUATION OF MINI-IMPLANT ANCHORAGE SYSTEM FOR EN-MASSE RETRACTION OF MAXILLARY ANTERIOR TEETH VERSUS CONVENTIONAL METHOD

Document Type : Original Article

Authors

1 P.H.D., Orthodontic Department, Faculty of Dentistry, Tanta University, Egypt

2 Professor of Orthodontic, Faculty of Dentistry, Tanta University, Egypt

Abstract

Objectives: The purpose of this study was to compare the skeletodental and soft tissue changes and the duration needed for closure of extraction space after en-masse retraction of maxillary anterior teeth using mini-implant anchorage system in the treatment of maxillary dentoalveolar protrusion cases compared with two step retraction with conventional method of anchorage reinforcement.
 
Materials and Methods: The study sample consisted of twenty adult orthodontic patients (3 males and 17 females) with maxillary dentoalveolar protrusion and required first premolar extraction and maximum anchorage. They were randomly divided into two treatment groups (10 subjects in each group). Group 1, anterior space closure with en-masse retraction aided by mini- implant anchorage system, or group 2, anterior space closure with two-step retraction technique aided by conventional method of anchorage. Lateral cephalometric head films were taken just before retraction of maxillary anterior teeth and immediately after closure of the extraction space for the evaluation of the treatment changes. Statistical analyses of the data were performed at a significance level of P <0.05.
 
Results: For the skeletal parameters, a statistically significant decrease in the facial vertical dimensions was seen in G1, but the variables in G2 showed no significant differences (P > 0.05). Anchorage loss, in both the horizontal and vertical directions, was noted in G2, whereas G1 showed anchorage gain and intrusion of molars. Group 1 had greater anterior tooth retraction (7.8 mm in 9.6 months) than did the conventional anchorage group (5.5 mm in 12.4 months). However, no significant differences in the mean retraction time were noted between the 2 groups. Upper incisors were intruded in G 1 (2.3 mm) and extruded (1.1 mm) in G 2. The soft-tissue response was greater changes in G1 with significant differences were found in the nasolabial angle and amount of upper lip retraction between the groups (P < 0.05).
 
Conclusion: Mini-implants provided absolute anchorage to allow greater skeletal, dental, and esthetic changes in patients requiring maximum anterior retraction, when compared with other conventional methods of anchorage reinforcement. However no differences in the mean retraction time were noted between the 2 groups.

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