Spontaneous Occlusal Changes after Lower First Permanent Molar Loss

Antonio David Corrêa NORMANDO, Maria do Carmo SILVA, Raquel Le BIHAN, José Leonardo SIMONE

The aim of the present study was to evaluate the influence of the loss of lower first permanent molars in the malocclusion development. Three hundred and eighty seven individuals in permanent dentition were examined. The mean age was 14.1 years (10.2 - 22.7). The sample was divided in groups according to the loss occurrence of de lower first permanent molars: 280 without loss (control group), 60 with unilateral loss (unilateral group) and 47 with bilateral loss (bilateral group). Two previously calibrated orthodontists carried out clinical exam of each individual. The following morphological aspects were examined: overjet, overbite, transversal relationship, arch alignment, midline deviations and sagital relationship. Qui-square test was used in order to analyze differences among groups. Results showed that unilateral or bilateral loss of the lower first permanent molars causes the same oclusal changes. Control Group and Molar Loss groups were similar regarding overjet (P= 0.594) and overbite (P=0.239), posterior crossbite occurrence (P= 0.986), upper midline positioning and on tooth alignment of the upper jaw (P=0.020). On the other hand, unilateral or bilateral loss of the lower first permanent molar causes a significant increase of the midline deviation on the lower arch (P= 0.000) and on the canine class II relationship (P=0.003 to the right side and P=0.002 to the left side). The loss, regardless if unilateral (P=0.018) or bilateral (P= 0.000), increased significantly lower anterior spacing. Thus one can conclude that the changes produced by unilateral or bilateral loss of the lower first permanent molars is not limited to the posterior segment of the dental arch, altering severely the lower anterior arch.

Keywords: First permanent molar loss. Oclusal changes. Malocclusion.

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