CAD/CAM vs Composite: Which is better?
- Jeff Davies
- Nov 15, 2015
- 2 min read
Photo courtesy of Elsevier. Found here: http://www.ncbi.nlm.nih.gov/pubmed/23287406
There has been quite the discussion on which of CAD/CAM or composites are better for a large restoration. If needing to fill a large MOD defect (5 mm depth by 5mm bucco-palatal width), the results and opinions have varied. However, it wasn't until a recent article by S Batalha-Silva et al, that really clarified the results for us. The in vitro study attempts to reduce variables while placing them in a controlled environment that can be easily reproduced. The research that was preformed was a fatigue resistance and crack propensity of large resin restorations. Paradigm MZ100 and Miris composites were used. After a series of fatigue testing, the survival rate of Paradigm MZ100 CAD/CAM group was 100% with minimal new crack propensity of 7%. The survival rate of Miris 2 composite direct restorations was 13% while their crack propensity was 47% with more severe cracks.
The longevity of a restoration is influenced greatly on things like, materials used, patient conduct, and dentist’s skills. One of the major problems, however, is the polymerization shrinkage stress of the the composite resins, especially with high C-factor defects. Strong adhesives can cause the composite material to exert cuspal stress which leads to movements and cracking. The best way to avoid polymerization shrinkage is to use post-polymerized restorations, composite resin inlay/onlays fabricated by CAD/CAM. It has been noted that some have found no clinical advantage of CAD/CAM milling over incremental direct restorations after a 5 year recall. Others have found a 85% survival rate of 3+ surface of direct composite restorations after 12 years. In spite of all of these recent reports, Indirect restorations are still considered the gold standard of restoring large defects. There are still the same polymerization shrinkage stresses but the forces are minimized in luting restorations because it is restricted to a thin cement layer, thus leading to superior marginal quality. It also needs to be noted that the luting procedure is the gold standard by reducing cracks in the cusp base. With cracks come possible microleakage and postoperative sensitivity. Other advantages that indirect restorations have is that they can provide anatomic contours, marginal adaptation, appropriate proximal contact, contour and occlusion because they are designed with the CAD/CAM program. The composite CAD/CAM blocks present acceptable wear properties. They are less brittle than porcelain and can be used in thinner layers, allowing more conservative preparation designs. The use of CAD/CAM, Paradigm MZ100 blocks, and immediate dentin sealing has proven to be a superior, conservative, and reliable biomimetic restoration.
With all of this information, it cannot be concluded that a large direct MOD defect is contraindicated for restoration with a direct composite, even with the higher crack propensity and failure at a higher load. These direct composite restorations can be beneficial to patient and practitioners who have limited access to newer CAD/CAM materials.
The article presents a myriad of information that can be further dissected down into other posts if time allowed. The research preformed is very thorough with lots of details. Please read the article which can be found here.
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