November 20, 2023
Prof. Trevor Burke, DDS, MSc, MDS, MGDS, FDS RCS (Edin), FDS RCS (Eng.), FFGDP(UK), FADM

Practice-based clinical research: Universal resin cements solve majority of traditional issues

Practice-based research results are a great resource for those who would like to avoid testing every innovation themselves. This article reveals how a recently introduced universal resin cement performs under real-life conditions.

When considering a new dental material, dental professionals look for evidence of the product’s suitability. In vitro or in vivo studies are conducted to provide this evidence, however, they’re usually carried out under idealized conditions. Even clinical studies are idealized in that they are open only to patients that meet specific eligibility criteria – typically young and healthy individuals. Consequently, this data may have limited applicability to the typical dental office.

Practice-based clinical research is different. It’s conducted by independent practitioners who assess the handling properties or long-term clinical performance of a material or device under real-life conditions and without preselecting patients. These evaluations are a valuable source of information for practitioners trying to identify a product that will suit their specific needs.

Globally, many different groups offer practice-based research, including the UKbased PREP panel (Product Research and Evaluation by Practitioners), founded in 1993. It consists of a group of 30 dental professionals who carry out product evaluations on a regular basis.


When a product evaluation is planned, all members of the PREP panel are informed about the upcoming project and asked whether they would like to enroll. The actual evaluators are randomly selected and provided with a questionnaire, instructions for product use, and a test kit containing the required materials. The evaluators use the products for a predefined period of time before completing the questionnaire, which is typically created by the
coordinators of the PREP panel and the product manufacturer. For product handling evaluations, general baseline data and specific information about the properties of the tested product are collected, along with any additional comments. A report is written based on the findings.


One product category that is particularly interesting for these evaluations is adhesive resin cements. Some dentists may remember working with early resin cement systems, which consisted of numerous different components and required acid etching, priming and bonding of the tooth structure, priming the restorative material, and meticulous moisture control. And when done correctly, the material – including the excess – adhered so well that it was barely removable. Newer resin cements offer less complicated procedures, but according to the PREP panel practitioners in a late 2019 evaluation, there was still room to simplify cementation protocols.

The product combination these practitioners were asked to test and evaluate was the new 3M™ RelyX™ Universal Resin Cement (fig. 1) and the dedicated bonding agent 3M™ Scotchbond™ Universal Plus Adhesive. The cement is universal in that it works on its own as a self-adhesive resin cement, but it can also be combined with the universal adhesive to boost its bond strength where needed.

Figure 1: 3M™ RelyX™ Universal Resin Cement in a newly developed syringe with 3M™ Scotchbond™ Universal Plus Adhesive.

`The 10 evaluators used the materials for 10 weeks. They placed 217 restorations, 76 with RelyX Universal Resin Cement in the self-adhesive mode and 141 with the cement in the adhesive mode (combined with Scotchbond Universal Plus Adhesive) (fig. 2).1

Figure 2: Split of indications in which 3M™ RelyX™ Universal Resin Cement was used as a self-adhesive cement and in adhesive mode with 3M™ Scotchbond™ Universal Plus Adhesive.

Apart from general baseline data collected for the study, the questionnaire focused on the following handling properties of the application system and the resin cement:

Application system:
• Ease of dispensing
• Ease of use
• Ease of mounting the mixing tip
• Ease of mounting the elongation tip

Resin cement:
• Shade offering
• Aesthetics
• Viscosity
• Ease of excess cleanup
• Overall satisfaction with the material in the self-adhesive mode
• Overall satisfaction with the material in the adhesive mode
• Likeliness of purchasing the material at average price
• Recommendation to colleagues


According to the results of the product test, the overall satisfaction with the available shades and esthetics of RelyX Universal Resin Cement was high. The evaluators rated the viscosity as ideal. Moreover, they stated that the handling and dispensing of resin cement from the newly developed syringe was very easy and the mixing tips were easy to attach. Removal of the material after tack curing received a score of 4.8 out of 5, with 90 percent of the evaluators confirming that the procedure was easier or at least as easy (one evaluator) as with the resin cement previously used. The evaluators were highly satisfied with the use of the product in both adhesive and self-adhesive modes, which was reflected in their stated interest in purchasing the material and product recommendation rate of 100 percent (fig. 3).

Figure 3: Overview of the most important results.

Figure 4a: Comfortable application of 3M™ RelyX™ Universal Resin Cement. Figure 4b: Easy excess clean-up.

Similar outcomes were obtained in a practice-based evaluation conducted by US-based DENTAL ADVISOR. After using the product combination for 425 restorations, RelyX Universal Resin Cement received a 99 percent clinical rating from the 12 dental professionals participating in the evaluation. The assessed properties were film thickness, viscosity, working time, setting time, ease of excess material removal and radiopacity.2


The excellent reception of this novel bonding and cementation system, with its newly designed, waste-reducing, self-sealing syringe and rotating tip, indicates that this resin cement has overcome the majority of challenges associated with early resin cements. The fact that two groups of evaluators from different countries and institutions obtained similarly good results is positive proof of the product’s well-balanced properties – that will suit the needs of many different
dental professionals.

The evaluations described above are just two examples of practice-based research by the PREP panel, DENTAL ADVISOR, and other research groups. The published reports are a useful source of independent information on new products that may help you simplify and streamline procedures in your dental office.

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