What is the survival rate of deciduous molars in cases with agenesis of premolar successors? A systematic review

Objectives: To systematically review the literature on the survival rate of deciduous molars in cases of agenesis of premolar successors.

Materials and methods: Four electronic databases and partial grey literature were searched up to November 2020. The PECOS eligibility criteria included (P) second deciduous molar (E) exposed to agenesis of a premolar successor (O) evaluated by the survival rate in the oral cavity, infraocclusion, and root resorption through (S) observational studies. Risk of bias (RoB) was assessed using the checklists from the Joanna Briggs Institute and the level of evidence was assessed using the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) tool.

Results: Three studies were included: one with low, one with moderate, and one with high RoB. Synthesis methods included the frequency of persistent deciduous second molars during the follow-up. Approximately 82% to 89% remained in the oral cavity after 5 to 13 years. The incidence of root resorption was 11%, and the infraocclusion was 1 mm. The level of evidence was considered low for each outcome. There was considerable RoB regarding the observational studies and a need for clinical and radiographic monitoring of the deciduous molars.

Conclusions: Maintaining a deciduous molar in the oral cavity in patients with agenesis of the premolar successor is a viable clinical choice since 82% to 89% of the retained molars evaluated were in good condition over a follow-up ranging from 5 to 13 years. Infraocclusion and root resorption did not seem to increase considerably. The level of evidence was considered low for each outcome.