Longitudinal Study of Root Growth in Maxillary Second Molars

Objectives: To measure for the first time longitudinal growth of the buccal roots of permanent maxillary second molars, compare mesial and distal root lengths (MRL, DRL) and compare symmetry of antimeres in male subjects.

Methods: Longitudinal periapical radiographs of 21 male subjects from the Iowa Facial Growth Study were captured and measured with software from Image Pro Express. Measurements were taken from the CEJ to root tip on the mesial aspect of the mesial root and distal aspect of the distal root. Double measurements were recorded and the mean used for statistical analysis with a paired-samples t-test. Intra-class correlations showed strong agreement between two measurements of a single observer (.99 for each surface). An alpha of 0.05 was chosen.

Results: The male subjects demonstrated MRL that were significantly longer than DRL at ages 8 to 14 and above age 20 (p<.05) for tooth 2 and for tooth 15. Root lengths of antimeres were similar as well at ages 8 to 14 and above age 20 (p>.05). Growth velocities peaked at age 11.25 for both teeth. The MRL of tooth 15 demonstrated a secondary lower velocity peak at age 14.

Conclusions: For males, growth of permanent maxillary second molar roots showed that the mesial root length was significantly longer than the distal root length, and that there was no significant difference in growth between the antimeres.

*This study was supported by a University of Iowa Dental Research Award.