Bilateral Asymmetry in Mandibular Tooth Development

¹ Cleft Palate Clinic, Center for Handicapped Children, Research and Educational Hospitals, University of Illinois at the Medical Center, Chicago, Illinois

Oblique cephalometric radiographs of 242 children were examined to study the intrabony spatial relationship and symmetry of eruption of the mandibular permanent canine and premolars.

Comparison between the right and left side in the same child at various ages disclosed asymmetry in tooth eruption in 131 of 242 children.

Comparison between children in the same age group disclosed pronounced differences in the bilateral spatial interrelationship of these teeth for 55 percent of the sample. Increments of intrabony eruption were neither regular nor constant.

Asymmetries in the vertical pattern of intrabony eruption of the lower canines and first and second premolars could be partially explained through the accelerating influence of local factors, such as carious or pulpotimized deciduous teeth, and because of the infrequent radiographic distortions resulting from transient changes in axial inclination of individual teeth during their eruption.

No significant difference was found between the sexes in the frequency of mandibular bilateral asymmetry of intrabony tooth spatial relationships.

The respective right and left duplicate tracings of the cephalometric oblique radiographs of 39 of the 40 children superimposed perfectly in their mandibular and tooth outlines, thereby establishing reliability of the methodology used in this investigation.