INTRODUCTION
Light-cure resins provide predictable results when restoring small and medium-sized cavities. Large cavities, however, present a unique set of challenges that can be more difficult to solve with resin-based composites. In large cavities, clinicians are concerned about the polymerization stress and shrinkage of composites, and they know that it can be difficult to achieve anatomic form, proper contours, interproximal and occlusal contacts, and marginal adaptation with resins.
As a result, indirect ceramic restorations are often the preferred treatment, but if a dental clinic does not have the digital workflow to offer patients a same-day solution, patients will have to wait weeks to have a final restoration. And there are also financial considerations. Not all patients can afford the high cost of indirect ceramic restorations, and we are responsible for offering those patients economical, durable, and aesthetic solutions.
Dentists are unique in their ability to combine the disciplines of medicine, engineering, and the fine arts. By applying this skill set and our understanding of the limitations of resins and the biomechanics of treatment sites, we are able to develop alternative resin-based solutions for large cavities that satisfy the needs of patients for whom laboratory-fabricated ceramic restorations may not be an option.
This article describes a direct-indirect technique for restoring large cavities in which the clinician works chairside to fabricate an indirect restoration with light-cure resin composites. The technique delivers a same-day restorative solution that offers cost savings; eliminates the issue of polymerization shrinkage; and overcomes the challenges of contours, contacts, and marginal adaptations.
CASE REPORT
In this case, old multi-surface amalgam restorations on the first and second molars were due for replacement (Figure 1). The patient could not afford ceramic restorations. This was an ideal case for the direct-indirect technique for resin restorations, which preserves tooth structure and delivers a durable, aesthetic solution in one day at a low cost. The technique is similar to what clinicians routinely do when making temporaries, but curing is done extraorally, and there are simple steps to ensure greater accuracy.
Figure 1. Initial presentation. Old amalgams would be replaced using a direct-indirect, one-visit technique.
Figure 2. Isolation and removal of old amalgam restorations.
Figure 3. After preparation refine- ment of 2 molars, an alginate impression was made.
After isolation and removal of the old amalgam (Figure 2), the preparation was refined, and an alginate impression was taken (Figure 3). A working model was made by filling the impression with light-body polyvinyl siloxane impression material (Figure 4), and this was backed with polyvinyl siloxane putty to provide rigidity to the model (Figure 5). After the polyvinyl siloxane had cured, the model was removed from the alginate impression (Figure 6). A second model was made using the same technique, which enabled a sectioning of the preparations, thus allowing direct access to interproximal margins.
Figure 4. The impression was filled with light-body polyvinyl siloxane impression material.
Figure 5. A base of polyvinyl siloxane putty was placed to provide rigidity.
Figure 6. The working model after removal from the alginate.
Using a layering technique, I applied a flowable/stackable composite to the model to build the restorations, light curing after each layer (Figures 7 to 9). Whenever possible, I prefer to use dynamic, biomimetic materials that can provide benefits to patients. For this case, I used ACTIVA Presto (Pulpdent). Presto is a bioactive material enriched with Crysta MCP (methacrylate-functionalized calcium phosphate) technology. Crysta is an MCP additive that supports remineralization of tooth structure with release and recharge of calcium and phosphate. Presto also contains fluoride and a rubberized-resin component that distributes occlusal forces, transmits the least amount of stress to the dentition, and provides toughness and resistance to chipping and fractures. The viscosity allows for easy placement in the silicone model, and the mineral content helps protect the teeth from secondary caries.
Figure 7. A first layer of ACTIVA Presto (Pulpdent), a bioactive, low-flow composite with Crysta MCP (methacrylate-functionalized calcium phosphate) technology, was placed in one molar on the model.
Figure 8. The first restoration was built up with ACTIVA Presto, and another one would be made.
Figure 9. Both ACTIVA Presto restorations in the working model. All polymerization stresses occur in the model stage, not while in the dentition.
By curing the restorations in the model outside the mouth, the polymerization stresses and contraction of the restorative material occur in the model stage; they do not occur in the tooth, and they do not affect the material-tooth interface. Any gap or dimensional discrepancies will have no clinical significance and will be corrected during cementation.
Figure 10. The flexibility of the model allowed for easy removal of the restorations.
Figure 11. The intaglio of the restorations.
Figure 12. Dissection of the second model.
The restorations are removed from the model (Figures 10 and 11). The second model is sliced interproximally to allow access to the box and the contacts (Figure 12), and the restorations are then adjusted, if needed, to perfect the anatomy and the contacts. They are easily removed from the second model and placed back in the first model to check for accuracy. This process can be repeated until the clinician is satisfied. Although some clinicians use this technique using only one model, I find that sectioning the second model facilitates access and accuracy.
Figure 13. ACTIVA BioaACTIVE-CEMENT (Pulpdent) was used to both cement the restorations and serve as a reline material to compensate for any dimensional discrepancies.
The restorations were ready for cementation (Figure 13). The cement played the double role of cement and reline material to adjust for dimensional discrepancies. For this, I use ACTIVA BioACTIVE-CEMENT (Pulpdent), which ensures that the properties of the restorations are shared by the cement. Because it is only a very thin film, polymerization stress and shrinkage are not an issue, and this is another great advantage of this technique. All stresses are outside the mouth and compensated for during cementation. Together with the ability to better access the proximal areas, this technique can provide a more accurate restoration than can be achieved with a direct resin technique when restoring large cavities. The treatment can be completed in one visit and offers an excellent solution for patients who have time constraints and for whom cost is a concern (Figure 14).
Figure 14. Molars restored with ACTIVA Presto using the direct-indirect technique. The multiple-unit case was completed at a low cost in one visit.
ABOUT THE AUTHOR
Dr. Barquero is a cosmetic dentist in San José, Costa Rica. He is the fourth generation of dentists in his family and teaches and lectures internationally on a variety of topics. See his oral rehabilitation work at the Instagram handle @drdelfinbarquero. He can be reached at drbarquero@delfinbarquero.com.
Disclosure: Dr. Barquero reports no disclosures.
