The Influences of Incisor Positional Changes Due to Fıxed Appliance Therapy on Tongue Position

Purpose: The positional changes of the tongue due to fixed appliance therapy, the relationship between the positional changes of lower incisor, the tongue and the attribution of this relationship was investigated. Materials & Methods: In this retrospective study, lateral cephalograms of pre and posttreatment records were evaluated. According to the mathematical differences of 1-NB parameters, subgroups namely; retrusion and protrusion groups were formed. Pretreatment measurements were performed from horizontal and vertical reference planes defined, posttreatment measurements were evaluated with the transportation of these reference lines using the total structural superimpositional method. The positional and linear dimensional changes of the tongue were evaluated using Rakosi tongue analysis with a modification of the reference line. Cephalometric tongue images were digitized and the tongue area were calculated. Results: The positional changes of the tip of the tongue were concordant with the positional changes of the lower incisor, elevation of the dorsum of the tongue and stoopness of the base of the tongue occured in the retrusion group. Tongue area increased in both groups. Conclusion: The tip of the tongue followed the movement of the lower incisor altered with fixed appliance therapy in sagittal direction. In cases where upper incisor retraction is planned, tongue tip should be expected to adapt by rising vertically. Keywords: incisors, fixed appliance therapy, cephalometric tongue position, Rakosi tongue analysis, tongue area.