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Inside Dentistry
January 2017
Volume 13, Issue 1
Peer-Reviewed

Biomimetic techniques are employed in the restoration of endodontically treated teeth for several important purposes:

• Preventing crown and root fracture
• Restoring occlusion and contours of the original or the idealized tooth
• Maintaining strong bond to dentin
• Sealing dentin to prevent re-infection
• Preventing occlusal forces from dislodging the bond
• Reducing stress/strain within the restoration.

Full crowns with posts do not fulfill these criteria because a stiffer crown impedes the normal flexure of the tooth substrate, resulting in a push-pull taking place at the gingival margin. Continued bending may result in cement washout and recurrent caries. Occlusal forces also may interact unfavorably with a cemented post, increasing the chance of dislodgment and fracture of either the post or root.

Clinical Case Presentation

With minimal tooth structure remaining, a matrix helps retain the composite “biobase” and can be accomplished as follows.

The pretreatment view shows deep caries (Figure 1). Following the completion of endodontic treatment (Figure 2 and Figure 3), debridement of dentin is completed. Next, a 4-mm channel is prepared into the gutta-percha using a No. 2 bur (long shank); the structure is then isolated and the canal is cleaned with ethanol, rinsed, and dried.

The dentin surface is then conditioned using bottle No. 1 of the self-etch, dual-cured resin (CLEARFIL™ SE Protect with Activator, Kuraray Noritake, www.kuraraynoritake.eu). Then, bottle No. 2 (SE Protect and Activator) is applied, lightly air-dried, and light-cured for 20 seconds. The 16-mm length of Ribbond (www.ribbond.com) is soaked in bottle No. 2, mixing well. A small amount of Ribbond Securing Composite is deposited into the prepared canal. Using the Ribbond Placement Instrument, the middle of the 16-mm length of Ribbond is inserted into the prepared and cleaned canal, leaving the ends to extend outward (Figure 4). The bonding resin is then light-cured.

The biobase is then constructed. First, a small amount of flowable composite (N’Durance® Flow, Septodont, www.septodont.com) is deposited in and around the Ribbond extensions, and light-cured. The flowable composite is used to seal the gingival margins; then a putty composite (N’Durance Universal, Septodont) is used to build up 2-mm proximal walls, and light-cured. The large internal portion of the biobase is built using a dual-cured composite (N’Durance Dimer Core, Septodont), and light-cured for 1 second as the material is deposited into the deeper layers of the preparation. Allow 5 minutes for complete polymerization. Then reduce the occlusal, and place a 360° bevel (Figure 5). Seal the biobase using light-cured SE Protect Bond, and cover the preparation with clear glycerin gel, light-cure again, and clean the preparation with alcohol. The impression can then be made. The lithium-disilicate biomimetic casting (e.max, Ivoclar Vivadent, www.ivoclarvivadent.com) is bonded into place (Figure 6) using a dual-cured luting cement (Panavia V5, Kuraray Noritake).

Conclusion

Biomimetic dentistry is focused on using restorative materials to replace lost tooth structure (enamel, dentin, and dento-enamel junction) and to replicate the biologic and mechanical aspects of natural tooth function. Biomimetic techniques and materials give a result where the restored tooth functions just as an intact one does, avoiding the stress and strain that can occur when an intracanal post is used in the restoration.

The placement of a post followed by a crown is not without complications such as re-treatment difficulties and fracturing of the root, crown, or post. Posts do not strengthen teeth; they only retain the composite base that supports the overlying casting, which contemporary bonding materials will accomplish. If there is minimal dentin remaining, polyethylene ribbon, soaked in bonding resin and light-cured, can provide a satisfactory matrix for the low-shrink composites that will comprise the biomimetic base.

This biobase has incorporated minimal or no contraction stress, provides a better bond, minimizes complications, and supports a tooth-conserving casting that functions more like a natural tooth than does a post-and-core buildup and a full-coverage crown.

Disclosure

The author has no relevant financial relationships to disclose.

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Randall G. Cohen, DDS

Private Practice

Yardley, Pennsylvania

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