Stress-Reduced Direct Composite (SRDC) Restorations

Why shrinkage stress matters: the C-factor

Feilzer and colleagues showed that the stress generated during setting depends on the ratio of bonded to unbonded composite surfaces, the configuration factor. A deep class I cavity, bonded on five walls with only one free surface, is the worst case. Reducing the C-factor of each increment is a core aim of stress-reduced techniques.

Layering technique

Deliperi and Bardwell described a successive cusp build-up technique for large posterior composites, in which each cusp is built separately so that increments do not bridge opposing walls. Combined with the dentin-first sequencing of decoupling with time, this lets each layer shrink with minimal restraint.

1. Remove caries using peripheral seal zone end points and seal the dentin.
2. Line the deep dentin with thin, low-stress increments.
3. Where the tooth is structurally compromised, incorporate fibre reinforcement in the dentin replacement.
4. Build the dentin replacement in small, oblique increments that contact as few walls as possible.
5. Build each cusp separately with enamel-shade composite.
6. Finish, polish and check the occlusion.

Fibre reinforcement

Leno-woven, ultra-high-molecular-weight polyethylene fibre ribbons (Ribbond is a well-known example) are used in some SRDC protocols to reinforce the dentin replacement in large cavities and cracked teeth. Deliperi, Alleman and Rudo described a "wallpapering" technique that lines the cavity with fibre to reinforce structurally compromised teeth.

Indications

• Large direct posterior restorations where an indirect restoration is not planned or not feasible.
• Teeth with cracks or undermined cusps where preservation of remaining structure is a priority.
• Replacement of failing amalgam or composite restorations.

Common pitfalls

• Placing large increments that bond to opposing walls at the same time, which maximises the C-factor of that layer.
• Bridging the cavity too early, before the deep dentin layers have been placed and the dentin bond has matured.
• Incomplete curing of increments in deep areas; check the output of the curing light and the distance to the cavity floor.
• Poor contact and contour in large restorations; a well-adapted matrix system is as important as the layering sequence.

Frequently asked questions

References

1. Feilzer AJ, De Gee AJ, Davidson CL. Setting stress in composite resin in relation to configuration of the restoration. J Dent Res. 1987;66(11):1636-1639. Find on PubMed (opens in a new tab)
2. Deliperi S, Bardwell DN. An alternative method to reduce polymerization shrinkage in direct posterior composite restorations. J Am Dent Assoc. 2002;133(10):1387-1398. Find on PubMed (opens in a new tab)
3. Deliperi S, Alleman D, Rudo D. Stress-reduced direct composites for the restoration of structurally compromised teeth: fiber design according to the "wallpapering" technique. Oper Dent. 2017;42(3):233-243. Find on PubMed (opens in a new tab)
4. Davidson CL, de Gee AJ, Feilzer A. The competition between the composite-dentin bond strength and the polymerization contraction stress. J Dent Res. 1984;63(12):1396-1399. Find on PubMed (opens in a new tab)
5. 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)