Assessment of the anchorage effect of transpalatal arch in tooth extraction treatment

Obtaining the maximum anchorage in the maxillary arch is mainly considered for preventing the first molars from moving towards the extraction site. Transpalatal arch is one of the instruments which provide anchorage. Up to now, a limited number of studies have assessed the effects of the transpalatal arch on sagittal, vertical, transverse, and rotational movements of the molars using both cephalograms and casts. Therefore, the present study aimed to evaluate the effect of the transpalatal arch on sagittal, vertical, transverse, and rotational movements of the maxillary first molars in the patients treated by the extractionof premolars with and without the transpalatal arch.
The present retrospective clinical trial was conducted on 68 patients who had finished the orthodontic treatment and were treated with (34 patients) or without the transpalatal arch (34 patients). Pre- and post-treatment lateral cephalograms and study casts were evaluated to determine the maxillary first molars movements during the treatment. The data were analyzed by the SPSS statistical software using paired samples t-test and Mann-Whitney U test.
No significant difference was found between the transpalatal arch and no-transpalatal arch groups regarding the mesial, vertical, and rotational movements of the maxillary first molars measured using cephalograms and study casts. However, a statistically significant difference was observed between the two groups regarding the transverse movements of the maxillary first molars (-0.19 ± 2.19 mm and -1.47 ± 1.25 mm, respectively; P=0.002).
In this trial, the transverse movement of the maxillary first molars of the transpalatal arch group was significantly less than that of the control group treated without the transpalatal arch.