Ensuring predictable cementation

Oct. 1, 2011
When selecting any material for a clinical procedure, dentists know that long-term clinical history is one of the best indicators of a product’s reliability.

by Santine Anderson, DDS

For more information on this topic, go to www.dental economics.com and search using the following key words: cementation, cement, debond rate, materials, bond strength, marginal staining, cement materials.

When selecting any material for a clinical procedure, dentists know that long-term clinical history is one of the best indicators of a product’s reliability. The long-term history of a cement is helpful in determining its suitability for use. A cement with a low debond rate is critical to ensure clinical success and long-term patient satisfaction.

A review of a cement’s properties and characteristics will help the dentist choose the correct material for each clinical case. Proper cement selection and use will facilitate exceptional performance over the long term, provide convenience, and help avoid repeat appointments and lost revenue due to cement failure. Dentists should also re-evaluate their choices as materials evolve and successive generations are introduced.

Practical considerations

When selecting a new cement, review literature on the clinical studies and conduct an individual, hands-on evaluation of the handling characteristics and dispensing system. Each clinician has unique preferences regarding the ease of mixing, viscosity, and ease of dispensing. A cement may perform well in the laboratory or in a clinical study, but if it does not fit into the clinical armamentarium, it may not be the cement of choice.

The thickness and flow of the cement are essential handling characteristics that dramatically impact the ease of use in the operatory. The dispensing method is also very important to the ease of integrating the new cement into a clinical situation. Some dentists and their assistants have a strong preference for a hand mix, capsule, or automix formula. The handling and dispensing of a cement can easily be identified and evaluated through a sales representative or during a trade show.

The ease of removing excess material is another important factor to consider. This may require a review of independent product evaluations or a trial sample in the clinician’s operatory. A cement may be light cure, dual cure, or self cure, but all cements have a window of time where the excess cement is most easily removed.

A review of technique guides or independent clinical articles may also be helpful in determining the ideal window of time for each cement. A material that easily removes excess cement is ideal, but a cement that sets too quickly can cause issues that take additional (operative time and equipment to remove.

Clinical results

The bond strength of a cement is one of the most important characteristics to consider. An adhesive or self-adhesive resin cement, which bonds the restoration to the tooth will typically offer dentists more confidence in terms of bond strength. Therefore, choosing a cement that offers predictable retention is essential. Long-term and short-term reporting on debonds can be found through product manufacturers, trade journals, and independent publications.

A cement intended for use in both the posterior and anterior should demonstrate a lack of marginal staining over the long term. While marginal staining may not always present a pressing issue in posterior restorations, it often means esthetic failure and a dissatisfied patient when used in the anterior.

When choosing a new cement, careful consideration should be given to the handling characteristics, dispensing, ease of excess removal, bond strength, and lack of marginal staining. A review of these factors, as well as other particular preferences of the individual dentist, can help in the selection of the most ideal cement. Dentists should periodically reevaluate their materials based on changes to the formula or new alternatives.

One generation to the next

As new generations of a preferred cement are introduced, examine the changes and the implications these changes may have on clinical performance. The clinical results from prior generations can often serve as a predictor of results for the new material. For example, RelyX™ Unicem 2 Self-Adhesive Resin Cement from 3M ESPE was recently introduced as the next generation of the product line, with changes made to its formulation to enable a more convenient delivery.

While long-term studies are underway on this new cement, the fact that the new product is substantially similar to the previous generation makes it likely that ongoing clinical results will be similarly positive.

The clinical history for the previous generation of this material demonstrates its solid foundation. A recently published seven-year evaluation of the cement found a very low (2.4%) debond rate from a total of more than 1,450 all-ceramic and PFM restorations.

Only 1.1% of patients reported postoperative sensitivity, highlighting one of the key advantages of using self-adhesive resin cement. The cement has also shown positive results on factors including microleakage, discoloration, and minimization of sensitivity.1 Results of early studies on this new product have shown no cement-induced hypersensitivity at one week and no detectable marginal gaps.

Economic advantages of a reliable cement

As dentists know, restorations that debond can result in loss of productivity or worse — loss of patients! A patient cannot be billed for a crown that debonded due to a cement failure, and thus the time spent to bring the patient back is lost revenue for the practice. Dentists should review the latest research on their cement system of choice and critically examine its clinical results, as well as the practical characteristics that affect its ease of use in the operatory.

By selecting a material with the best combination of reliable data and ease of use, dentists can feel confident in the long-term strength of their restorations, and the ultimate success of the dental care they provide.

1] Farah JW, Powers JM, eds. 3M ESPE RelyX™ Unicem Self-Adhesive Universal Resin Cement 7-Year Clinical Performance. Dent Advis 27(4); May 2010.

Santine Anderson, DDS, is a practicing partner at Enspire Dental and an assistant editor of “The Dental Advisor.” She is a graduate of the University of Michigan School of Dentistry, and received her B.S. in chemistry from Albion College. Dr. Anderson can be reached at [email protected].

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