Canine Guidance Vs Group Function: A Comparison Of Root Length

There is a tendency to extrude the maxillary canines during orthodontic treatment without consideration of the original occlusion which could be either group function (GF) or canine guided occlusion (CG). Creating CG in a patient that did not have it before will introduce para-function which compromises periodontal health. There is a general assumption that canine roots are longer than those of the premolars thus allowing them to withstand the occlusal forces during CG. We hypothesize that there is no difference in root lengths between canines and premolars in GF, and that the canine roots are longer in subjects with CG.

Objective: The purpose of this research was to assess the difference in root lengths between premolars and canines in subjects with either group function (GF) or canine guided (CG) occlusion.

Method:

Peri-apical radiographs of 34 patients with either GF or CG were collected from private practices that document the functional occlusion (more data to be analysed). Root lengths of canines, 1^st and 2^nd premolars from the same quadrant were measured from the root tip perpendicular to a line that connects the most distal and mesial points of the cemento-enamel junction. The root lengths of the 1^st and 2^ndof each subject were summed and their average was compared to the canine root length. ANOVA was used to compare the root lengths within and between subjects with GF and CG of the canines and premolars.

Result:

There were statistically significant differences in root lengths between the canines and premolars in GF and CG (P<.0001). The root lengths of the canines were much longer than those of the premolars in CG compared to those in GF.

Conclusion:

The canines root length is much longer than the premolars in canine guided occlusion compared to group function.