Dentofacial Morphology in Third Molar Agenesis

Objective:In the literature, some studies show a relation between tooth agenesis and craniofacial morphology, whereas other authors conclude that dental agenesis exerts little influence on dent facial structures. The objective of this study was to determine the existence of any relation between bilateral agenesis of the maxillary and/or mandibular third molars and the anteroposterior dimensions and vertical growth pattern of the jaws.Subjects and Methods:Sixty-eight subjects between the ages of 13 and 17 years with bilateral agenesis of maxillary third molars (group I, n=37), bilateral agenesis of the mandibular third molars (group II, n=19), and agenesis of all third molars (group III, n=12) as well as 33 subjects without third molar agenesis (group IV) were selected from the radiology archive. A before and after treatment orthopantomograph and the pretreatment cephalometric radiograph of the subjects were used. Several angular and linear parameters representing the anteroposterior dimensions and vertical growth pattern of the jaws were measured on cephalometric radiographs. The data were analyzed by Kolmogorov-Smirnov test, analysis of variance for 1 factor, and independent-samples t test. Statistical significance was set at p,0.05.Results:When the agenesis groups (groups I, II, and III) were compared with the control group, it was found that all parameters representing the anteroposterior dimensions of both jaws (A-Ptm, CoA, ANS-PNS, CoB, CoGn, CoPog, and ABRB) were significantly smaller in all agenesis groups (p,0.05). The parameters reflecting the vertical growth pattern did not represent any difference among the groups (p.0.05).Conclusion:In subjects with bilateral or total third molar agenesis, the anteroposterior dimensions of both jaws were smaller in comparison with subjects without tooth agenesis. Vertical growth pattern of the jaws did not differ among the groups.