Eruption of the first permanent molars

[摘要] Introduction:due to its long duration, the process of eruption of permanent dentition maybe affected by a number of systemic and/or local factors. Objective: identify the initial age for the eruption of the first permanentmolars and the moment of their occlusion among students from a school locatedsouth of Mexico City. Methods: a longitudinal descriptive study was conducted at Espartacoelementary school south of Mexico City. The study sample consisted of 53 students(31 girls / 22 boys) whose parents granted their informed consent. The variablesstudied were sex, chronological age and eruption of the first permanent molars.The sample was checked every three months by two qualified examiners in a well-litplace using dental mirrors. The following criteria were applied: unerupted,initial eruption and functional occlusion. Further examination was performedto include all occluded molars. Estimation was made of central tendency anddispersion measures by chronological age (initial eruption and functional occlusion),as well as the average duration of the eruption process. Data were processedwith the statistical software SPSS version 21.Results: initial eruption age was the following: 6.69 years for the firstpermanent upper right molars, 6.68 for the upper left, 6.67 for the lower right,and 6.59 for the lower left. The first molar to occlude was the upper right(7.29 years) and the last ones were the two lower molars (7.56). Overall averagetime to reach occlusion was 0.6 year for the upper right molar, 0.7 for theupper left, 1.1 for the lower right and 1 year for the lower left.Conclusions: in the population studied average age for the start of eruptionof the first permanent molar was 6.6 years. Among boys the first lower molarsare the ones that start eruption and the last to reach occlusion.

[学科分类] 基础医学

[关键词] school children;molars;occlusion.