The Peripheral Seal Zone: Caries Removal End Points in Biomimetic Dentistry

The concept

Traditional teaching often aimed to remove all soft or stained dentin before restoring a tooth, even when this led to pulp exposure. Adhesive dentistry changed the reasoning: if the restoration is sealed to sound tissue around its periphery, bacteria left in deep, affected dentin are deprived of nutrients and the lesion can be arrested.

Alleman and Magne formalised this as the peripheral seal concept. The cavity periphery, adjacent to the DEJ, is where enamel and the best-quality dentin for bonding meet, and where the seal against the oral environment is made. That zone is cleaned completely. The pulpal area is treated differently, according to lesion depth and pulp status.

Alignment with international consensus

The International Caries Consensus Collaboration reached compatible recommendations: in deep lesions in vital teeth, carious tissue should be removed selectively, leaving hard dentin at the periphery and allowing softer, leathery dentin to remain pulpally, in order to maintain pulp health while achieving a durable seal.

Clinical sequence

1. Isolate the tooth with a rubber dam and gain access to the lesion, preserving sound enamel where possible.
2. Identify the dentinoenamel junction and the peripheral zone of the cavity.
3. Use a caries detector dye and tactile assessment to guide removal of infected dentin and stained tissue at the periphery until the dentin is hard and sound.
4. In the central, pulpal area, remove soft infected dentin selectively; leave firm or leathery affected dentin where further removal would risk pulp exposure.
5. Disinfect and seal the cavity with an adhesive protocol so the periphery is bonded to sound tissue.
6. Build up the restoration using a stress-reducing technique to protect the new bond.

Key terminology

• Dentinoenamel junction (DEJ): the interface between enamel and dentin, with a structure that resists crack propagation.
• Infected dentin: soft, heavily contaminated dentin that cannot be remineralised.
• Affected dentin: partially demineralised dentin with an intact collagen framework that can remineralise when sealed.
• Caries detector dye: a stain that helps visualise denatured collagen and guide removal.

Clinical considerations and pitfalls

• Diagnose pulp status before deciding on selective removal: the approach applies to vital teeth without signs of irreversible pulpitis.
• Do not leave stained or soft tissue at the periphery for convenience; the peripheral seal depends on bonding to sound enamel and dentin.
• Caries detector dyes can over-stain sound circumpulpal dentin, so interpret staining together with hardness and location rather than removing everything that takes up dye.
• Protect the result with a well-sealed restoration placed with a stress-reducing technique; a leaking restoration undermines the rationale for leaving affected dentin.
• Document the depth of the lesion and the end points used so that the tooth can be monitored at recall.

Frequently asked questions

References

1. Alleman DS, Magne P. A systematic approach to deep caries removal end points: the peripheral seal concept in adhesive dentistry. Quintessence Int. 2012;43(3):197-208. Find on PubMed (opens in a new tab)
2. Schwendicke F, Frencken JE, Bjørndal L, et al. Managing carious lesions: consensus recommendations on carious tissue removal. Adv Dent Res. 2016;28(2):58-67. Find on PubMed (opens in a new tab)
3. Alleman DS, Nejad MA, Alleman CDS. The protocols of biomimetic restorative dentistry: 2002 to 2017. Inside Dentistry. 2017;13(6):64-73. Find on PubMed (opens in a new tab)
4. Van Meerbeek B, De Munck J, Yoshida Y, et al. Buonocore memorial lecture. Adhesion to enamel and dentin: current status and future challenges. Oper Dent. 2003;28(3):215-235. Find on PubMed (opens in a new tab)