Effects of non-compliant intraoral distalizers on the soft tissue profile, A systematic review

Abstract

Background: Practicing orthodontists have special interest in Class II malocclusion cases as they constitute a significant percentage of the cases they treat. Maxillary molar distalization is the most frequently used nonextraction treatment in the correction of Class II malocclusion to establish a Class I molar and canine relationships. The common and unwanted side effect of these intraoral methods is the mesial shift of premolars and incisors leading to anchorage loss which might affect the profile and soft tissues of the patient. Aim: The objective of this systematic review is to look at the soft tissue effects associated with the use of non-compliant intraoral distalizers for the correction of Class II malocclusion.

Materials and Methods: The systematic search included Cochrane Library, PubMed, Scopus and Ovid journals identifying 4 prospective or retrospective studies matching the inclusion criteria. The inclusion criteria considered were Class II malocclusion cases using noncompliant intraoral tooth-borne distalizers, a control group of untreated Class II patients or non-compliant intraoral skeletal-borne distalizers. The main outcome assessed were the soft tissue effects including the nasolabial angle, upper and lower lips to E-plane. Secondary outcomes included the degree of incisor anchorage loss. Appliances with conventional or skeletal anchorage designs were considered for the review. The Final articles included were three non-randomized retrospective studies and one prospective study. The date of the last search was May 15, 2021. The methodological index of non-randomized studies (MINORS) was used to assess the articles included. The studies had close results and assessed to have high risk of bias.

Results: In total, 436 studies were identified for screening, and 4 studies were eligible. The mean change in the upper lip to E-plane varied from 0.1mm to 0.7mm. The mean change in lower lip to E-plane varies from 0.0mm to 0.6mm. While the mean change in nasolabial angle showed an increase of 1.7 (15.5) degrees. Dental changes were also assessed. The SNupper incisor mean change ranged from 0.1 degrees with the use of distal screw appliance to 5.0 with the use of the pendulum. The mean change in the overjet was 0.0mm with the use of bone anchored pendulum appliance BAPA. The values increased with the use of other types of distalizers with the highest value of 1.5mm with the use of the distal jet. The first premolars can also be affected with the use of distalizers. However, using a skeletally anchored distalizer can lead to distalization of the first premolars as reported by (Polat-Ozsoy, 2008) with the use of BAPA with a mean change of -2.7mm when measured from a vertical plane. Mesialization of the first premolars happened when a conventional pendulum appliance was used with a mean change of 4.0mm.

Conclusion: There is no significant difference in the nasolabial angel, upper lip and lower lip positions, and hence the soft tissue profile of the patient with the use of various types of noncompliant intraoral distalizers when treating Class II malocclusion cases. The use of skeletally anchored distalizers had fewer side effects on the soft tissue measurements, however these differences were not significant.