Quadrant Dentistry: Root Canal Treatment Followed by Biomimetic Class II Composite Overlay Under Absolute Isolation
Abstract
Modern restorative dentistry demands preservation of tooth structure while ensuring long-term biomechanical stability. This case report presents a quadrant dentistry approach involving root canal treatment followed by a biomimetic Class II composite overlay. Strict rubber dam isolation, microscope-assisted procedures, adhesive protocols, and stress-reduced composite layering were employed to restore function, strength, and biological harmony. The case highlights how adhesive overlays can serve as a conservative alternative to indirect restorations when executed with precision.
Clinical Situation and Diagnosis
The patient presented with a posterior tooth exhibiting deep caries with pulpal involvement. Clinical symptoms and radiographic findings confirmed irreversible pulpitis without apical pathology. The remaining tooth structure was compromised, particularly in the marginal ridge area, necessitating an approach that could both seal the endodontic space and reinforce the tooth against future fracture.
The treatment plan involved:
- Single-tooth root canal treatment
- Immediate coronal sealing
- Definitive biomimetic Class II composite overlay
Treatment Objectives
- Achieve predictable disinfection and obturation of the root canal system
- Prevent coronal microleakage through immediate restoration
- Reinforce weakened cusps using an adhesive overlay concept
- Restore proximal contact, occlusal anatomy, and functional load distribution
- Maintain maximal tooth structure through a direct restorative approach
Step-by-Step Clinical Protocol
1. Quadrant Isolation
The procedure was carried out under full quadrant rubber dam isolation. This ensured moisture control, bacterial exclusion, and optimal visibility throughout both endodontic and restorative phases. Isolation also allowed seamless transition from RCT to definitive restoration in the same session.
2. Access Cavity and Root Canal Treatment
Access cavity preparation was performed conservatively, preserving pericervical dentin. Root canal treatment was carried out following standard chemo-mechanical protocols:
- Canal negotiation and working length determination
- Mechanical preparation with copious irrigation
- Final irrigation protocol to ensure canal cleanliness
- Three-dimensional obturation achieving a dense apical and coronal seal
A post-operative radiograph confirmed adequate obturation without overextension or voids.
3. Immediate Coronal Seal
Immediately after obturation, the pulp chamber was sealed to eliminate coronal leakage. This step is critical in preventing bacterial reinfection and is a key factor in long-term endodontic success.
4. Cavity Design for Biomimetic Overlay
Instead of aggressive cuspal reduction for a full-coverage crown, a biomimetic preparation was adopted:
- Unsupported enamel and weakened dentin were selectively removed
- Cusps were preserved where structurally sound
- Internal line angles were rounded to reduce stress concentration
This design allowed the composite to function as a bonded overlay rather than a conventional intracoronal filling.
5. Matrixing and Proximal Wall Reconstruction
A sectional matrix system was used to rebuild the missing proximal wall and establish a tight, anatomically correct contact. Proper proximal reconstruction provided:
- A sealed cervical margin
- Correct emergence profile
- Stable contact to prevent food impaction
This step also served as a foundation for the overlay buildup.
6. Adhesive Protocol
A strict adhesive protocol was followed:
- Selective enamel etching
- Application of a universal adhesive
- Thorough solvent evaporation and controlled light curing
Adhesive procedures were performed under isolation to ensure maximum bond strength and durability.
7. Biomimetic Composite Overlay Build-Up
The tooth was restored using an incremental composite layering strategy to mimic natural tooth biomechanics:
- Dentin replacement layers provided internal stress absorption
- Enamel layers restored cusp form and occlusal anatomy
- Incremental placement minimized polymerization shrinkage
Cuspal coverage was achieved selectively, reinforcing weakened areas while preserving intact enamel wherever possible.
8. Occlusal Adjustment, Finishing, and Polishing
Occlusion was carefully adjusted to eliminate high contacts, especially in functional cusps. Finishing and polishing refined surface texture, anatomy, and marginal transitions, ensuring long-term plaque resistance and patient comfort.
Outcome and Follow-Up
The final restoration demonstrated:
- Excellent marginal adaptation
- Tight proximal contact
- Harmonious occlusion
- Radiographic confirmation of a dense root canal fill and well-sealed coronal restoration
The patient remained asymptomatic, this validating the biological and mechanical success of the treatment.
Discussion
Endodontically treated teeth are structurally compromised and prone to fracture if restored inadequately. Biomimetic composite overlays offer a conservative yet effective alternative to crowns by reinforcing the tooth through adhesion rather than removal of sound tissue. When combined with immediate coronal sealing and quadrant isolation, this approach delivers predictable long-term outcomes.
Conclusion
Root canal treated posterior teeth can be successfully restored using direct biomimetic Class II composite overlays when strict isolation, adhesive protocols, and stress-controlled layering are respected. Quadrant dentistry enhances efficiency while maintaining the highest standards of biological and restorative care.
References
- Magne P, et al. Stress-reducing direct composite restorations in posterior teeth. J Adhes Dent.
- Dietschi D, Spreafico R. Current clinical concepts for adhesive restorations of posterior teeth. Pract Periodontics Aesthet Dent.
- Ray HA, Trope M. Periapical status of endodontically treated teeth in relation to the technical quality of the root filling and the coronal restoration. Int Endod J.
- Opdam NJM, et al. Longevity of posterior composite restorations: a systematic review. J Dent Res.
- Magne P. Bonded restorations for endodontically treated teeth: biomechanical considerations. Quintessence Publishing.
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