Orthodontic significance of anomalies of tooth eruption

Abstract

Among the factors initiating or complicating malocclusions are anomalies of tooth eruption. Under consideration here were (1) the anomalous malposition and retarded eruption of the maxillary permanent central incisor which may follow traumatization and devitalization of the deciduous predecessor and (2) the anomalous retarded, and perhaps ectopic, eruption of the mandibular second premolar associated with overretention of the deciduous second molar. Thirty-seven cases of anomalous maxillary permanent central incisor eruption were investigated, leading to the conclusions that: 1. 1. Lingual eruption of these teeth was due to the lessened resorptivity of a retained nonvital deciduous tooth. 2. 2. Labial eruption followed early extraction of the nonvital deciduous tooth, eliminating a normal barrier to the usual downward and forward eruptive path of the permanent tooth. 3. 3. Retarded eruption may be the result of the formation of a fibrous tissue at the site of deciduous tooth infection, forming a retarding barrier to eruption. Overretention of a mandibular second deciduous molar can result in generalized malocclusion where: 1. 1. Excessive tooth structure is present in an arch containing deciduous second molars as well as permanent second molars, causing crowding within the arch or increasing a potential toward a Class III malocclusion. 2. 2. The mandibular second deciduous molars have been retained while the maxillary second deciduous molars have been shed, permitting establishment of a permanent molar cuspal relationship wherein there are forces capable of producing a Class II malocclusion. In cases where the overretained deciduous molar has been extracted as a preventive measure, the result may be a localized malposition involving an ectopically erupting premolar into a space that: 1. 1. Remained or was maintained oversize, permitting rotation in the absence of proximal contact. 2. 2. Closed excessively, particularly in the presence of an erupted or erupting permanent second molar, causing blocking out of the premolar.