A Comparison of Outcomes Between Tandem Mechanics and Guided Eruption Therapy

Introduction: Crowding is a common diagnosis in mixed dentition orthodontic patients. There are a limited number of early treatment options for these patients. One option includes the guided eruption (GE) extraction sequence in which the orthodontist prescribes a sequence of extractions of primary and permanent teeth in order to alleviate crowding. Another treatment option is Tandem Mechanics (TM). This technique involves the pairing of cervical headgear with a lower arch wire and intermaxillary elastics to expand the arches and distalize the terminal teeth in order to create space. Hypothesis/Objective: To determine the biomechanical effects on patients treated with both modalities through cephalometric analysis and compare them to each other. Methods: Initial and post treatment cephalometric radiographs were collected for 42 patients treated with TM and 30 with GE. The sample was divided into subgroups by anteroposterior and vertical growth patterns. The treatment effects for the overall sample and subgroups were evaluated using single sample t-tests. The treatment results of the overall sample and subgroups were determined by comparing the overall mean effects of both modalities to one another using independent samples t-Tests. Results: TM caused maxillary growth restriction, increased vertical skeletal height, tipped the palatal plane clockwise, distalized upper molars and reduced lip procumbency. GE reduced vertical skeletal dimensions, retroclined incisors, protracted molars, and increased facial convexity. Both reduced upper lip procumbence, tipped lower molars distally, retroclined lower incisors, and reduced soft tissue convexity according to the Z-angle. GE had a significantly longer average treatment time. These same patterns were noted across all subgroups. Conclusions: TM demonstrates better efficacy in treating class II skeletal tendencies and lip protrusion despite having less effect on upper incisor angulation. GE demonstrates superior control in the vertical dimension and significantly retroclines all incisors.