Ankylosed primary molars: results and treatment recommendations from an eight-year longitudinal study.

A total of 263 ankyloscd primary molars in 107 children aged three to 12 years was studied for four years. Forty-six children remained in the study for eight years. Observation of affected dentitions showed that the condition was likely to recur. Three clinical pa~terns for the condition are described. Typically, maxillary molars became ankylosed earlier and demonstrated more severe in[raocclusion than mandibular molars. Mandibular first molars usually remained slightly or moderately in#aoccluded; mandibular second molars and maxillary first and second molars showed progressively severe infraocclusion. Following either extraction or ex~oliation of the affected molars, the succedaneous bicuspids did not differ in either coronal morphology or in distribution of enamel surface defects from bicuspids preceded by non-ankylosed molars. Mandibular first molars usually ex[oliated on schedule; failure to employ timed extraction for severely infraoccluded molars resulted in reduced alveolar bone support [or the bicuspid. Treatment recommendations are developed based .upon the molar type, clinical pattern, and the severity of in#aocclusion.