Deep margin elevation in permanent incisors with crown-root fractures: A laboratory study

OBJECTIVES: This laboratory study evaluated the effect of deep margin elevation (DME) on the marginal integrity and fracture resistance of anterior teeth with crown-root fractures. MATERIALS AND METHODS: Fifty-two extracted permanent human maxillary central incisors were randomly divided into four groups. All teeth received a standardized simulated crown-root fracture, selective enamel etching followed by universal adhesive application, resin-based composite (RBC) build-up (conventional or bulk-fill), root canal treatment, and glass fiber post placement. Crown preparations were performed either entirely in natural tooth structure with subgingival finish lines (DME absent) or partially on the RBC build-up, yielding supragingival finish lines (DME present). Marginal integrity was assessed microscopically at baseline, after initial thermomechanical loading (TML), and after extended TML. Fracture resistance was determined by load-to-fracture testing. Statistical analyses included Kruskal-Wallis, Dunn’s post hoc, and Fisher’s exact tests (α = 0.05). RESULTS: Median marginal continuity remained 100% across all groups. Fracture resistance (1,305-1,595 N) showed no significant differences between groups. Fractures during TML occurred exclusively in groups without DME. CONCLUSIONS: Within the limitations of this in vitro study, DME did not adversely affect marginal integrity or fracture resistance of restored anterior teeth. In contrast to non-DME groups, specimens with DME did not exhibit failures during TML. CLINICAL RELEVANCE: DME restorations can maintain high marginal integrity and load-bearing capacity in anterior teeth with crown-root fractures. These findings provide preliminary evidence supporting DME as a conservative approach for managing anterior crown-root fractures in select cases, with confirmation needed from clinical studies.