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 UK-based 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.
Product testing and evaluation procedure
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.
Handling properties of adhesive resin cements
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.1