Permanent Molars, Secondary Retention Of
Description
Secondary retention is the cessation of eruption of a tooth after emergence that does not result from a physical barrier in the path of eruption or an abnormal position of the tooth. Permanent molars are less frequently affected than deciduous molars. The major characteristic of a secondarily retained molar is infraocclusion, which may result in malocclusion because of tilting of the neighboring teeth and overeruption of antagonists. The disorder can also result in loss of the retained molar and neighboring teeth due to caries and periodontal disease and in deformation of the facial skeleton (Raghoebar et al., 1992).
See also 125350 and 273050 for phenotypes with shared features of secondary retention of permanent molars.
Clinical FeaturesVia (1964) suggested autosomal dominant inheritance for submerged deciduous molars. Bosker and Nijenhuis (1975) performed linkage studies using blood and serum groups in 5 pedigrees segregating autosomal dominant reinclusion of the first molar and found suggestive linkage to blood group P (111400), obtaining a maximum lod score of 2.14 at theta = 0.00.
Bosker et al. (1978) examined 50 affected and 138 unaffected members of 9 unrelated families segregating autosomal dominant familial reinclusion of permanent molars; 4 additional cases were confirmed by dental records and 1 by family history, for a total of 55 affected individuals. Although ankylosis had been believed to be responsible for reinclusion of permanent molars, histologic and scanning electron microscopy of removed reincluded molars showed that ankylosis was absent in a substantial number of these cases. Bosker et al. (1978) concluded that genetic factors play an important role in maintaining elements in occlusion, and that these cases of familial reinclusion of permanent first molars with or without involvement of second molars represented a distinct genetic entity. Proffit and Vig (1981) noted that the radiographs of the index cases studied by Bosker et al. (1978) showed the same characteristics as their own patients with primary failure of eruption (PFE; 125350).
Pelias and Kinnebrew (1985) reported 12 affected individuals of a 4-generation kindred in which dental ankylosis was associated with fifth finger clinodactyly. There was posterior open bite, reduction in the height of the lower face, and mandibular prognathism. The pattern of inheritance was autosomal dominant. Pelias and Kinnebrew (1985) stated that dental ankylosis is the result of abnormal fusion of dental cementum with alveolar bone. Because of the fusion, affected teeth fail to erupt to meet their counterparts in the other jaw. Bone deficiencies result from abnormal eruption and migration of the ankylosed teeth and suboptimal growth stimulation for the supporting alveolar bone.
Raghoebar et al. (1992) studied first-degree relatives of 39 probands with secondary retention of permanent molars. Familial occurrence was shown in 5 (13%) of the 39 families; in each of the 5 families, 1 of the parents was affected, compatible with autosomal dominant inheritance. Affected members of the same family showed much variability as to which molars were affected, and 4 patients from 3 families had involvement of deciduous as well as permanent molars. Raghoebar et al. (1992) concluded that secondary retention of permanent molars is an etiologically heterogeneous condition in which about 13% of cases are caused by the presence of an abnormal autosomal dominant gene.
Ahmad et al. (2006) suggested that secondary retention of teeth may represent 1 of 2 independent conditions incorporated within primary failure of tooth eruption, with the other condition being localized complete failure of tooth eruption. However, they also noted that PFE might represent a single disorder of tooth eruption with differing degrees of severity, a hypothesis supported by the fact that these 2 manifestations can occur in the same subject.
NomenclatureRaghoebar et al. (1992) noted that secondary retention of tooth eruption has been described in the literature as submerging, ankylosing, Halbretention, infraocclusion, and reinclusion. The designation 'secondary retention' is preferred because the retention occurs secondarily to the postemergent eruptive spurt of a later phase of the eruptive process.