Contemporary Dental Cements An Inside Look at a Vital Dental Material

Author : Dental Product Shopper
Published Date 06/28/2011
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Contemporary Dental Cements An Inside Look at a Vital Dental Material

In recent years, advances in dental material?s technology and the demand for esthetic restorations have modified the clinician?s approach to and selection of dental cements for the definitive luting of indirect restorations. The purpose of this article is to present a brief review of contemporary definitive dental cements, and to provide clinical recommendations for their selection.

Contemporary Dental Cements An Inside Look at a Vital Dental Material

In recent years, advances in dental material?s technology and the demand for esthetic restorations have modified the clinician?s approach to and selection of dental cements for the definitive luting of indirect restorations. The purpose of this article is to present a brief review of contemporary definitive dental cements, and to provide clinical recommendations for their selection.

Classifications

There are several ways of classifying dental cements. When classified by their primary setting reaction, all cements can be classified as acid-base, with the exception of resin cements, which set by polymerization. 1 Cements also can be classified by their main component (ie, zinc phosphate, glass ionomer, resin). For the purposes of this discussion, we will divide cements into conventional (zinc phosphate, polycarboxylate, and glass ionomer) and contemporary (resin-modified glass ionomers and resin), which seems to be a more practical approach.2

Resin-Modified Glass Ionomers

Resin-modified glass ionomers (RMGIs) were created by improving the mechanical properties of conventional glass ionomers through the addition of polymerizable resins. They are regarded as dualcured materials, setting by an acid-base reaction and polymerization. Advantages of RMGIs include some adhesion to tooth structure without a separate bonding agent, fluoride release, infrequent postoperative sensitivity, and increased resistance to solubility compared to conventional glass ionomers. However, the hydrophilic nature of these cements could lead to expansion, which may result in the fracture of high-glass containing ceramics (eg, luecite reinforced).3 Resin cements should be used with these restorations. To avoid inconsistencies in the mix and ensure the cement will have its maximum properties, automix, capsule, or paste-paste delivery systems should be selected over powderliquid presentations. The scientific literature has confirmed the clinical efficacy of these cements.4,5

RMGI cements are the most frequently used cements in North America for the cementation of porcelain-fused to metal crowns, full-cast, and highstrength (eg, zirconia, alumina) ceramic restorations.6 Recently, the addition of reinforcing materials such as hydroxyapatite and metallic nanofillers has been suggested to improve the properties of glass ionomer cements.7,8

Resin Cements

The need for color selection, translucency, or greater retention may require the use of a different type of cement. For these clinical situations, resin cements may be the luting agent of choice. Improvements in their formula and an increased demand for all-ceramic restorations have expanded their use.9

Resin cements are dimethacrylatebased (eg, Bis-GMA), and are therefore similar in composition to flowable composites, although with a lower filler content.10 They can be light-, self-, or dual-cured, with selection dictated by the clinical situation. Light-cured resin cements are indicated when the polymerization light can have easy access to the cement, such as during the cementation of porcelain veneers.11 The other curing modes should be selected if there are any areas where the polymerization light will not reach the cement with ease. Metal castings, thick partial-coverage and opaque full-coverage all-ceramic restorations are some clinical examples where the selection of resin cements with a chemically activated curing mode would be useful. Resin cements have high compressive and tensile strength, very low solubility, and are highly resistant to moisture absorption.12

Resin cements available today may or may not require the separate adhesive treatment of tooth structure. In the case of the former, this can be accomplished with a total-etch bonding system or a self-etch bonding agent. The latter category incorporates a self-etching primer into the resin cement, simplifying clinical procedures and greatly reducing postoperative sensitivity.9 Bond strengths, however, may be lower than cements with a separate self-etching primer13 and adhesion to enamel may represent a weak link for these cements.14

Resin cements that require a separate total-etch bonding system usually offer various color and translucency choices. They are typically used for the cementation of veneers and other highly translucent restorations where the aforementioned factors could influence the final shade of the restoration. In these situations, hydrofluoric acid-etch and silane treatment of the silica-based ceramic are required for proper bonding. Because zirconia and alumina restorations cannot be acid-etched, their inner surface should be pretreated with a ceramic primer to improve bond strengths with the selected resin cement.15 In the presence of exposed dentin surfaces, proper application of the total-etch bonding system is mandatory to avoid postoperative sensitivity.16

Clinical Recommendations

Routine cementation of cast metal, porcelain- fused-to-metal, and high-strength ceramic restorations can be easily accomplished with RMGI. In addition, RMGI should be the cement of choice for caries- prone patients because of its fluoride release. In the presence of less-than-ideal tooth preparations, or whenever increased retention is desired, resin cements with or without a separate self-etching step should be selected. Resin cements requiring the application of a separate total-etch bonding system should mainly be reserved for highly translucent restorations in the esthetic zone.

Conclusions

As the use of traditional cements has decreased, the use of contemporary cements has become commonplace. There is no available material that works best for all clinical situations. Several cements are necessary to provide comprehensive dental care, and their selection should not be an arbitrary choice. Therefore, practitioners should familiarize themselves with each type of cement and select the one most adequate for each clinical scenario.

References

1. Christensen GJ. Why use resin cements? J Am Dent Assoc. 2010;141(2):204-206.

2. Donovan TE, Cho GC. Contemporary evaluation of dental cements. Compend Contin Educ. Dent 1999;20(3):197-199, 202-208, 10 passim; quiz 20.

3. Leevailoj C, Platt JA, Cochran MA, et al. In vitro study of fracture incidence and compressive fracture load of all-ceramic crowns cemented with resin-modified glass ionomer and other luting agents. J Prosthet Dent. 1998;80(6):699-707

4. Qvist V, Poulsen A, Teglers PT, et al. Fluorides leaching from restorative materials and the effect on adjacent teeth. Int Dent J. 2010;60(3):156-160.

5. Jokstad A. A split-mouth randomized clinical trial of single crowns retained with resin-modified glass-ionomer and zinc phosphate luting cements. Int J Prosthodont. 2004;17(4):411-416.

6. Self-adhesive resin cements: a replacement or an alternative? Clinicians Rep. 2009;2(11):1, 3.

7. Lee JJ, Lee YK, Choi BJ, et al. Physical properties of resin-reinforced glass ionomer cement modified with micro and nano-hydroxyapatite. J Nanosci Nanotechnol. 2010;10(8):5270-5276.

8. Moshaverinia A, Roohpour N, Chee WLW, Schricker SR. A review of powder modifications in conventional glass-ionomer dental cements. J Mater Chem 2010(21):1319-28.

9. Christensen GJ. Should resin cements be used for every cementation? J Am Dent Assoc 2007;138(6):817-9.

10. Weiner RS. Dental cements: a review and update. Gen Dent 2007;55(4):357-64; quiz 65-6, 75-6.

11. Rasetto FH, Driscoll CF, von Fraunhofer JA. Effect of light source and time on the polymerization of resin cement through ceramic veneers. J Prosthodont 2001;10(3):133-9.

12. O?Brien WJ. Dental materials and their selection. 3rd ed. Chicago: Quintessence Pub. Co.; 2002.

13. Cantoro A, Goracci C, Carvalho CA, Coniglio I, Ferrari M. Bonding potential of self-adhesive luting agents used at different temperatures to lute composite onlays. J Dent 2009;37(6):454-61.

14. Radovic I, Monticelli F, Goracci C, Vulicevic ZR, Ferrari M. Self-adhesive resin cements: a literature review. J Adhes Dent 2008;10(4):251-8.

15. Suh B, Chen L, Brown D. Bonding to zirconia: Innovation in adhesion. Compend Contin Educ Dent 2010;31(Special Issue 1):2-7.

16. Perdigao J, Geraldeli S, Hodges JS. Total-etch versus self-etch adhesive: effect on postoperative sensitivity. J Am Dent Assoc 2003;134(12):1621-9.

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