In recent years, many brands of resin cement have been introduced for various uses in dentistry. I receive many questions from practitioners about the desirability of using resin cements instead of resin-modified glass ionomer (RMGI) cements for routine cementation of crowns and fixed prostheses. The subject is confusing.
RMGI is among the most popular materials used for dental cements. Example brands include RelyX Luting Plus Cement (3M ESPE, St. Paul, Minn.) and GC Fuji Cem (GC America, Alsip, Ill.). The major reasons dentists have accepted these cements are their well-known lack of associated postoperative tooth sensitivity, acceptable strength and fluoride release.
It has become common knowledge that resin cements are necessary for some clinical situations, such as cementing tooth-colored inlays and onlays, moderate-strength ceramic crowns and ceramic veneers. The reasons a practitioner might prefer resin cement for these situations are several: the numerous colors in which it is available; its high strength, which is greater than that of RMGI cement; and the fact that RMGI cement, unlike resin cement, expands when setting, therefore threatening breakage of some categories of moderate-strength indirect ceramic restorations.
This article discusses my observations and opinions with regard to the various types of resin cements, the uses for which they are indicated and why they are indicated in specific situations.
 |
RESIN CEMENTS USING A PRECEMENTATION TOTAL-ETCH BONDING AGENT
|
|---|
When resin cement was introduced for cementing indirect restorations, most companies recommended that the cements be used after a total-etch bonding system had been applied to the tooth preparation. Clinicians complied with the instructions. The clinical results were unpredictable because of the occasional occurrence of postoperative tooth sensitivity. In general, clinicians have reported more tooth sensitivity when using total-etch systems versus self-etching bonding agents in restorative dentistry. In one study, 4,446 practicing dentists reported that the occurrence of postoperative sensitivity after total etching was twice that after self-etching.1 However, some studies conducted in dental schools have not shown a sensitivity difference between the two types of etching.2,3
It is understandable that with the impeccable use of total-etch procedures before use of resin cement, such as in a highly controlled school study, dentists can prevent postoperative sensitivity. However, in most busy offices with the usual need to conserve time and treat many patients in a day, any deviation from the prescribed total-etch procedure may lead to the sensitivity described. With the exceptions noted below, I do not recommend the use of a total-etch procedure before cementing restorations with resin cement.
Because of the described potential of disagreeable postoperative tooth sensitivity, I suggest that clinicians use total-etch bonding before seating restorations with resin cements when enamel is the dominant tooth structure present. Such situations could involve veneers cemented on tooth surfaces that are all-enamel or enamel margins of tooth-colored inlays and onlays. In some cases, when marginal enamel appears to be fragile or small cracks in enamel are present, I recommend etching the enamel with a total-etch product, washing it off rapidly to avoid etching the dentin and then applying a self-etching bonding agent to the entire tooth preparation.
Popular brands of resin cement for veneers and tooth-colored inlays and onlays are Variolink II (Ivoclar Vivadent, Amherst, N.Y.), NX3 (Kerr, Orange, Calif.), Calibra (Dentsply Caulk, Milford, Del.) and RelyX Veneer Cement (3M ESPE). These cements vary in viscosity and radiopacity, but I have observed that each has found acceptance among clinicians. All of them have multiple colors for the esthetically demanding locations described previously.
|
ALTERNATIVES TO TOTAL ETCHING
|
|---|
As a result of clinicians’ reporting postoperative tooth sensitivity when using total-etch bonding systems before cementing restorations with resin cements, manufacturers began producing resin cements intended for broad use that incorporated self-etch bonding systems. Less postoperative tooth sensitivity was reported with the use of resin cement containing self-etching primers. In a study of 4,820 patients, 0.1 percent experienced sensitivity, all of which subsided within three weeks.4
Two types of techniques have evolved for the use of resin cement: one involving a separate self-etching bonding agent and another involving resin cements that contain self-etching bonding agents. In my observation, use of resin cements requiring total-etch bonding agents appears to have diminished in situations in which dentin is present on the tooth preparation.
Resin cements requiring a separate self-etching bonding agent.
Popular resin cements that require the use of a separate self-etching bonding agent are Panavia F (Kuraray America, New York City) and Multilink Automix (Ivoclar Vivadent). Both of these resin cements have a two-component liquid self-etching bonding agent that is intended to be applied to the tooth preparation before the restoration is seated with the resin cement. The self-etching bonding agent is intended to seal the dentinal canals and provide bond to both the enamel and the dentin. It has been my observation that clinicians report minimal-to-no postoperative sensitivity when these cements are used properly.
These self-etching resin cements have been used by practitioners for situations in which the strength of resin cement is needed, dentin is present and the known postoperative tooth sensitivity associated with total-etch resin cement needs to be avoided. Such situations are seating of the moderate-strength, pressed all-ceramic crowns on full-crown tooth preparations and tooth-colored ceramic or polymer inlays and onlays. A minor limitation for these cements is their narrow range of color selection. Most brands have only a few colors, which usually are adequate for most of the situations previously described.
Resin cements containing an incorporated self-etching bonding agent.
Popular resin cements containing an incorporated self-etching bonding agent are RelyX Unicem (3M ESPE), MaxCem (Kerr), Multilink Sprint (Ivoclar Vivadent) and MonoCem (Shofu Dental, San Marcos, Calif.). Other manufacturers, seeing the clinical and financial success of these cements, are bringing other self-etching resin cements to the market.
The growing popularity of resin cements with incorporated self-etching bonding agents appears to be related directly to their ease of use, dual cure and lack of associated postoperative tooth sensitivity.4 However, research varies regarding the strength of these cements in relation to resin cements that do not have the self-etching bonding systems added.5,6 With few exceptions, clinicians are reporting clinical success with these self-etching resin cements, but long-term observation of their clinical success is needed.
An important item related to these cements appears to be overlooked by many practitioners. Although the popular RMGI cements provide fluoride release,7 the self-etching resin cements do not contain fluoride.
In my opinion, self-etching resin cements are indicated primarily for clinical situations that require significant strength because the strength of the restoration to be cemented is insufficient, that involve short tooth preparations, or that require a complete absence of expansion during setting (such as occurs with the RMGI cements),8 and in which ease of use is important. Although more clinical research is needed regarding the importance of fluoride release from cements, I do not recommend the use of self-etching resin cements for situations in which high cariostatic characteristics are needed. I feel that the best cement for routine cementation of porcelain-fused-to-metal crowns and fixed pros-theses is RMGI, as discussed previously.
|
RECOMMENDATIONS FOR USE OF RESIN CEMENTS
|
|---|
The table
presents my recommendations for the use of resin cement, recommendations I make on the basis of my clinical experience, the many comments of practitioners around the world and my interpretation of a review of the literature.
TOP
RESIN CEMENTS USING A...
ALTERNATIVES TO TOTAL ETCHING
