211 - Predictors of Successful Second Molar Substitution: Retrospective Study

Abstract:

Purpose: The aim of this retrospective study was to determine factors influencing successful second molar substitution following extraction of the first permanent molar in patients aged 5 to 15 years.

Methods: A chart review was conducted of patients treated at the UTHealth Houston School of Dentistry who underwent one or more permanent first molar extractions between 2005 and 2025. Radiographs were evaluated and scored using the Demirjian developmental stages to classify the second molar and second bicuspid and Patel toolkit to determine the angulation of the permanent second molar. Successful substitution was defined as presence of a visible contact without marginal ridge discrepancy at a minimum of nine-month post-extraction follow up. Generalized linear models assessed how success varied across explanatory variables.

Results: Eighty-three patient charts and 118 teeth were analyzed. Visible contact was observed in 49% of cases, absence of marginal discrepancy in 23%, and overall successful substitution in 22%. Tooth extracted (P < .001), age at extraction (P = .002), Demirjian stage of the permanent second molar (P = .003) and second bicuspid (P = .018), and presence or absence of third molar (P = .004) were significant predictors of success. Ethnicity, gender, overjet and overbite, and angulation of mandibular second molar were not significant (P > .05).

Conclusion: Permanent second molar substitution following extraction of permanent first molar remains a viable treatment option for permanent first molars that are non- or questionably-restorable. Providers must consider patient-specific factors to ensure timing of extraction is ideal for clinical success.

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