A radiographic study of third molar crown development in a group of Nigerian children

The present study assessed developmental stages of third molar crowns in a group of Nigerian children and compared development across arches in relation to chronological age and sex.MethodologyPanoramic radiographs of 560 healthy Nigerian children aged 5 to 15 years were reviewed. The stages of development of third molar crowns across arches were assessed and determined using the criteria defined in Gravely's classification of crown formation. A score was recorded in each quadrant for each child. Data was analyzed using Epi-info 6 version for windows. Statistical significance was inferred at P < 0.05.ResultsMales 267 (47.7%), females 293 (52.3%). Mean age 10.4 years (SD52.5). Earliest evidence of crypt formation was observed at age 5.0. Mean age for stage 1 of crown calcification was 7.55, 7.75, 8.24 and 8.88 for the lower right, lower left, upper right and upper left quadrant of the jaws respectively. Differences observed between males and females were significant for stage 1 upper right molar crown development, (P = 0.03). In children 12 years and above, approximately 75% of the crowns visible on radiographs were at least half formed. Mean age for stage 5 of crown formation and initiation of root formation was between 13.10 and 13.43 years. The proportion of agenesis among children aged 12 years and above was 0.7.ConclusionsThe first sign of third molar crown development was observed as early as age 5. A positive correlation was observed between third molar development and chronological age. Proportion of agenesis in children aged 12 years and above was 0.7.