Digital Evaluation of Pathologic Root Resorption in Primary Mandibular Molars and Its Implications on Succedaneous Unerupted Premolars.

Background: Pulpal infection from primary molars may have periapical implications resulting in pathological root resorption (PRR). There is little clarity regarding its effects on succedaneous teeth. Therefore, the aim of the study was to evaluate the effects of PRR on the root formation and eruption of their succedaneous premolars. Materials and methods: Digital orthopantomograms (OPGs) were obtained of subjects aged between 6 and 9 years. A split-mouth study design was planned, wherein the affected side had to contain a carious mandibular primary molar (MPM) showing PRR. The corresponding tooth on the contralateral side had to be unaffected, showing physiologic root resorption alone. Premolar root formation, premolar eruption, and MPM root resorption pattern were measured digitally. A sample size of 56 OPGs were used for the study. Statistics were carried out using STATA version 17.0 (StataCorp). Shapiro-Wilk, Cohen's Results: Greater amounts of premolar root formation and intra-alveolar eruption had occurred resulting from PRR of the overlying primary molars. A greater amount of PRR was observed on the distal and mesial roots of the first and second molars, respectively. Conclusion: PRR in primary molars enhances the root formation and intra-alveolar eruption of their succedaneous premolars. Clinical significance: This study objectively demonstrates that PRR in primary mandibular molars accelerates root formation and intra-alveolar eruption of succedaneous premolars. The split-mouth design minimizes interindividual variability, strengthening the evidence for the proposed space replacement theory of eruption. These findings clarify previous inconsistencies and enhance clinical understanding of premolar eruption patterns in pediatric dentistry.