The Relationship Between Cervical Headgear Treatment And Maxillary Third Molar Space: A Retrospective Controlled Study

Abstract

Introduction: The effect of headgear on the space available for the eruption of upper third molars needed further investigation. Only a few studies looked at the after-treatment effect of headgear on that space, and none have evaluated the long-term effect after the average age of third molar eruption. Therefore, this retrospective study evaluated the short and long-term effects of cervical headgear on the space and eruption of the maxillary third molars and their long-term eruption status. Materials and Methods: Records of Class II cases treated with cervical headgear were collected at the following time points: (T1) before treatment, (T2) after treatment, and (T3) taken at least 4 years after T2. An untreated control sample was collected from the Bolton-Brush study records. They were matched for age at each time point and malocclusion. Lateral cephalograms were used to measure the distance from the distal surface of the maxillary first molar (U6) to the pterygoid vertical plane (PTV). The third molar status at T3 was categorized into five groups: impacted, extracted, erupted, congenitally missing, and formation stage. Thirty-three cases were included in the cervical headgear group and 19 in the control group. Results: The position of U6 changed significantly between the headgear and control group at T2 but was similar at T3. In the headgear group, the U6 was significantly distalized (3.3 ±2.9 mm) between T1 and T2 (P=0.006), however, there was a significant relapse of 5.9 (±4.6) mm between T2 and T3 (P<0.001). In the control group, the distance between U6 and PTV increased significantly from T1 to T2 (4.8 ±4.4mm) with minimal change from T2 to T3 (1.5 ±4.8mm). There was no significant relationship between headgear use and third molar status (p=0.108). Conclusion: Headgear caused a temporary decrease in the U6-PTV distance that was recovered later. This decrease was not observed in the control group. Using cervical headgear to correct Class II malocclusion does not increase the risk of upper third molar impaction.