AARD 2009

In the past decade, there has been an explosion in the volume of dental literature. New journals have been introduced on a regular basis and are competing with many of the established journals with a long history of publication. Dentists are urged to practice evidence-based dentistry at a time when commercialization of the profession has become rampant and materials are routinely brought to the marketplace with little or no clinical documentation.

While the volume of scientific literature has increased dramatically, the quality of the evidence produced leaves much to be desired. Many articles are simply clinical reports that, while they may be of interest to clinicians, are low in the desired hierarchy of evidence. Many clinical trials are neither randomized nor controlled, and also are underpowered by virtue of relatively small samples sizes. Most authors of systematic reviews lament the fact that there are not enough properly conducted randomized con-

trolled clinical trials (RCTs) to answer the primary question posed by the review.

The primary purpose of this review is to assist practicing dentists in clinical decision making and to guide them to the best scientific evidence published in 2008. The Committee on Scientific Investigation has carefully reviewed and selected articles published in 2008 because they believe the resultant data contributes to the advancement of the practice of evidence-based dentistry. Comments on study design, statistical analysis, and the relative strengths of the findings are included to aid the reader in interpretation of the results.

The analysis of the scientific literature published in 2008 is divided into 6 sections: (1) caries and pulp pathology; (2) periodontics; (3) dental materials; (4) occlusion, temporomandibular disorders, and sleep disordered breathing; (5) prosthodontics; and (6) implant dentistry.

CARIES AND PULP PATHOLOGY

A number of studies were published last year on pulp capping, particularly on the effect of different materials on pulp capping outcomes. One such study evaluated the expression of fibronectin and type III collagen in human pulps following pulp capping with calcium hydroxide (calcium hydroxide powder followed by placement of Dycal; Dentsply Caulk, Milford, Del) or a 2-step, etch-and-rinse adhesive (Single Bond; 3M ESPE, St. Paul, Minn).1 Fibronectin is considered to be a marker for reparative dentin, and type III collagen is synthesized during the initial healing phase of tissue repair. Forty-six healthy pre- molars indicated for orthodontic extraction were randomly assigned to 1 of 3 groups: (1) control, no pulp cap; (2) pulps exposed and capped with adhesive; or (3) pulps exposed and capped with calcium hydroxide. Pulp caps were covered with resin-modified glass ionomer and restored with composite resin. Teeth were extracted 7 or 30 days after treatment.

The results showed that calcium hydroxide-capped pulps had similar type III collagen and fibronectin expression as the control (noncapped) pulps, and both of these were significantly greater than the expression in the adhesive-capped pulps. Furthermore, the adhesive-capped pulps showed persistent inflammatory process throughout the study period. This study demonstrated that healthy pulps, even in the absence of bacterial contamination, did not produce extracellular matrix elements when capped with a 2-step, etch-and-rinse adhesive.

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