Deep Margin Elevation in Endodontically Treated Posterior Teeth

This prospective split-tooth controlled clinical study aims to evaluate the periodontal response associated with deep margin elevation (DME) in endodontically treated posterior teeth restored with CAD/CAM systems.

Endodontically treated teeth frequently present with extensive structural loss due to caries, previous restorations, or endodontic access cavity preparation, which compromises the structural integrity of the tooth. In such cases, deep subgingival margins are commonly encountered, making isolation, adhesive procedures, and restorative treatment more challenging. Deep margin elevation (DME) is a minimally invasive technique used to relocate subgingival margins coronally to the cemento-enamel junction level using resin composite, facilitating adhesive procedures, digital impression taking, and CAD/CAM restoration placement. However, the periodontal effects of DME remain unclear and require further clinical investigation.

A total of 45 restorations will be included in patients aged between 18 and 65 years who present with at least one endodontically treated posterior tooth with extensive coronal destruction. A split-tooth design will be used, where one proximal surface requiring deep margin elevation will be assigned as the test surface (DME), while the opposing proximal surface with supragingival or equigingival margin will serve as the control.

All clinical procedures will be performed at the Department of Restorative Dentistry, Faculty of Dentistry, Hacettepe University. Before treatment, professional cleaning will be performed using a pumice-water mixture and polishing instruments to remove plaque accumulation. All restorative procedures will be carried out under rubber dam isolation using ×3 magnification dental loupes.

During the DME procedure, isolation will be achieved using a sectional matrix system and wedges. A universal adhesive system (G-Premio Bond, GC, Tokyo, Japan) will be applied following enamel conditioning with 37% phosphoric acid for 10-15 seconds. The subgingival margin will then be elevated to the enamel level using a high-filled injectable composite resin (G-ænial Universal Injectable, GC, Tokyo, Japan).

All restorations will be fabricated using a chairside CAD/CAM system (CEREC Omnicam, Dentsply Sirona, Bensheim, Germany) and milled from a resin nanoceramic hybrid block (Cerasmart 270, GC, Tokyo, Japan) according to the manufacturer's instructions.

The internal surface of the restoration will be sandblasted with 50 µm aluminum oxide, cleaned with alcohol, and treated with G-CEM ONE Adhesive Primer (GC, Tokyo, Japan). The tooth surface will be conditioned with 37% phosphoric acid, followed by the application of G-Premio Bond. Restorations will be luted using a self-adhesive resin cement (G-CEM ONE, GC, Tokyo, Japan). Excess cement will be removed after short light exposure, and final polymerization will be performed using a high-intensity LED curing unit (Bluephase N, Ivoclar Vivadent), with 10 seconds of curing per surface.

Finishing and polishing procedures will be completed using fine diamond burs, aluminum oxide-coated polishing discs, and polishing systems. Occlusion will be checked and adjusted when necessary.

Periodontal parameters will be recorded at baseline (T0) and at follow-up visits at 1 week, 6 months, and 12 months. The primary outcome measure will be bleeding on probing (BOP), assessed at six sites per tooth, and the presence of bleeding at any site will be recorded as positive. Secondary outcome measures will include probing pocket depth (PPD) measured in millimeters and plaque index (PI). Gingival index (GI) will also be recorded as an additional parameter.

Restorations will be evaluated according to FDI criteria by two calibrated clinicians who are blinded to the intervention. Functional, biological, esthetic, and patient-related parameters will be assessed. Patient satisfaction will be evaluated using a 5-point Likert scale including general, esthetic, and functional satisfaction.

Sample size calculation was performed using G*Power 3.1 software based on McNemar test assumptions for paired data (α=0.05, power=80%). Based on estimated discordant proportions (p10=0.27 and p01=0.03), the minimum required sample size was calculated as 40 teeth. Considering a potential 10% dropout rate, a total of 45 restorations will be included.

Statistical analysis will be performed using SPSS software. Differences in BOP between test and control surfaces will be analyzed using the McNemar test. PPD and PI values will be analyzed using the Wilcoxon signed-rank test. Changes over time will also be evaluated using paired statistical methods. A significance level of p<0.05 will be considered statistically significant.

This study is expected to provide clinically relevant evidence regarding the periodontal effects of deep margin elevation and contribute to evidence-based decision-making in the restorative management of endodontically treated posterior teeth.