Clinical research in adhesive dentistry

In the field of adhesive dentistry, innovative products and new techniques are continually introduced to simplify and enhance clinical procedures. In this scenario, clinicians should keep in mind that more and more attention has to be placed on laboratory and clinical research as an indispensable source of evidence.

Complex phenomena may be better studied and observed in vitro, after having reduced the system under investigation to an extreme level of simplification, so that the investigator can focus on a limited number of experimental variables. Following such an approach, however, it often becomes challenging to understand how the different variables, that have been carefully and individually analyzed in vitro, would actually interact all together under the real circumstances naturally occurring within a living organism.

As a consequence, the main drawback coming with in vitro research is the limited chance to extrapolate its findings back to general worldwide accepted conclusions. On the other hand, in vivo studies (such as animal studies, clinical trials, observational/non-interventional studies) are experiments on living organisms, and are recommended as the principal means of answering important clinical questions: among them, clinical trials are often referred to as the “gold standard” source of evidence. Nevertheless, their execution may be complex, time consuming and costly. Clinical trial costs can vary widely depending on the number of patients being sought, the number and location of research sites, the complexity of the trial protocol. Moreover, gaining an IRB approval from the local ethic committee is a mandatory requirement.

Numerous new adhesive systems are put on the market every year. Most of them claim that their application requires even less time and only one step, or that the antibacterial additive increases the longevity of the restoration. Similarly, a huge amount of adhesive restorative materials has been introduced over the last years: new ceramics with improved strength, innovative resin composites which are based on advanced filler technologies, machinable blocks for an easy chair-side production of indirect restorations. Generally new materials are indeed introduced on the basis of reliable in vitro research performed by the companies and by designated independent institutions. However, the market strongly pushes for sudden innovations and quite often new products and techniques lack of trustworthy clinical guidelines, which should be ideally based on the systematic review of “time consuming” randomized clinical trials.

The rules of market cannot be changed. Nevertheless, well conducted post-marketing clinical studies still should be seen as a fundamental requirement for a sound clinical practice.


Camillo D’Arcangelo

Professor of Restorative Dentistry

Chief of the Restorative and Endodontics Department

University of Chieti, Italy