regional odontodysplasia ( ro ) is a rare developmental dental anomaly that involves ectoderm and mesoderm derived tissues .
the prevalence of this condition is still not clear since the studies reported till date have mainly been based on case reports .
although several factors such as local trauma , infection , ischemia , neural damage , and somatic mutations of neural crest cell migration have been advocated , the underlying pathophysiology of the condition remains unclear .
the maxillary teeth are more commonly affected , and only four cases of mandibular involvement have been reported so far .
the teeth with ro often display a brownish or yellowish discoloration and most frequent clinical symptoms accompanied by this anomaly are failure of eruption and gingival enlargement .
radiologically , the affected teeth illustrate hypoplastic crowns and lack of contrast between enamel and dentin is usually apparent . enamel and the dentin are very thin , displaying a  ghost - like appearance .  the other pathognomic radiological characteristics are enlarged pulp chambers , short roots , and open apices .
a 33-month - old boy reported to the department of pediatric and preventive dentistry of our college with the complaint of delayed eruption of teeth in the lower jaw .
there was no history of abnormal tooth anomalies on both maternal and paternal part of the family .
extra - oral examination revealed normal symmetrical face and normal skin , hair , and nails .
the intra - oral examination revealed an adequate maxillary arch with fully erupted primary teeth .
all the maxillary teeth appeared normal except for some carious involvements in molars [ figure 1 ] .
although all the primary teeth were visible in the mandibular arch , they were not fully erupted and seemed to be embedded in abnormal , slightly hyperplastic alveolar mucosa .
furthermore , these teeth revealed abnormal crown morphology with yellowish discoloration and hypoplastic enamel [ figure 2 ] .
normal maxillary arch with a full complement of teeth hypoplastic crowns and gingival hyperplasia in entire mandibular arch the orthopantomogram ( opg ) [ figure 3 ] which was taken after detailed clinical examination , showed a full complement of maxillary deciduous teeth and follicles of permanent teeth except for tooth germs of premolars , which was normal for his age .
however , in the mandibular arch , all the primary teeth showed a striking  ghost - like  appearance [ figure 3 ] .
the demarcation line between enamel and dentin in these teeth was not clear , and enamel was hypoplastic .
none of the permanent tooth germs were seen except for the follicles of first molars .
the laboratory investigations showed that the serum calcium , phosphorus , sodium , and potassium levels were in normal range .
since the child was only 33 months old , and none of the teeth showed any abnormal mobility , extraction was not carried out .
however , gingival biopsy examination revealed the odontogenic tissue in the epithelium and intramesenchymal calcifications . on the basis of clinical and radiographic findings , a diagnosis of ro was proposed .
maintenance of proper oral hygiene and regular follow - up examinations for monitoring the developing dentition was advised .
considering the age of the child , conservative treatment was preferred over extractions because it preserves oral functionality and esthetics until the end of growth period after which a more definite treatment could be planned .
regional odontodysplasia is a rare tooth anomaly that affects maxillary teeth more often with very less tendency to cross the midline .
however , cases have been reported with bilateral or multiquadrant involvement . in the present case ,
clinical and radiographic findings were consistent with that of ro , but this case was notable due to involvement of the entire mandibular arch . till date , only four cases of mandibular involvement have been reported .
the cause of the present case also remains unknown because the patient 's past medical history and family history was noncontributory , and no congenital or acquired diseases were reported .
regional odontodysplasia has shown to affect both primary and permanent dentition . in the present case ,
delayed development of permanent tooth germs in the mandibular arch was also evident which was in agreement with some cases reported previously .
typical clinical features in this case included gingival hyperplasia and teeth embedded in the gingival overgrowth ; both of these features were consistent with the majority of cases reported previously .
a differential diagnosis of ro includes hereditary conditions , such as dentin dysplasia , dentinogenesis imperfecta , and amelogenesis imperfecta as these conditions may present similar features of enamel hypoplasia , abnormal pulp morphology , and calcification .
hereditary developmental anomalies of enamel and dentin , however , usually affect the entire dentition rather than segments .
dentinogenesis imperfecta type iii bears close resemblance to ro but can be excluded if opalescent dentine , bell - shaped crowns , and family history are absent .
factors such as the patient 's age , extent of the lesion , and eruption of the teeth , medical history , and esthetics need to be carefully considered . for the present case ,
in addition , since the opg showed absence of developing permanent tooth germs , it was thought appropriate to preserve the primary teeth .
follow - up examinations were planned to observe the development of mandibular permanent tooth germs .
the case presents unique clinical and radiographic features of ro involving the entire mandibular arch in a child aged 33 months .
a dental professional must be prepared to manage cases of dental anomalies , providing an opportunity for early diagnosis , adequate monitoring and treatment plans that minimize the after - effects on the patient 's development . in cases of ro
, treatment depends on the age of the patient , extent of the involvement of the teeth , and the individual functional and esthetic needs .
 regional odontodysplasia ( ro ) is a rare developmental anomaly involving both mesodermal and ectodermal components in primary or permanent dentition . 
 it affects the maxilla and the mandible or both ; however , maxilla is more commonly involved . 
 this article reports the case of 33-month - old boy who came with the chief complaint of delayed eruption of mandibular teeth . 
 findings of clinical and radiographic examination were consistent with those of ro . 
 maxillary dentition was unaffected . clinical and radiographic features and treatment options 
 are discussed . 
Introduction
Case Report
Discussion
Conclusion