Cochrane reviews are generally well-respected meta-analyses that are designed to answer important clinical questions. A Cochrane study ended the battle between OralB and Sonicare for supremacy in the electric toothbrush market. Their analysis showed that the OralB brush (at the time) was a better plaque-remover.

Single Versus Multiple Visits for Endodontic Treatment of Permanent Teeth: A Cochrane Systematic Review¹
Lara Figini, DDS, Giovanni Lodi, DDS, PhD, Fabio Gorni, MD, Massimo Gagliani, MD

The Cochrane Collaboration promotes evidence-based healthcare decision making globally through systematic reviews of the effects of healthcare intervention. The purpose of this systematic review was to investigate whether the effectiveness and frequency of short-term and long-term complications are different when endodontic procedure is completed in one or multiple visits. Randomized and quasi-randomized controlled trials enrolling patients undergoing endodontic treatment were identified by searching biomedical databases and hand-searching relevant journals. The following outcomes were considered: tooth extraction as a result of endodontic problems and radiologic failure after 1 year, postoperative discomfort, swelling, analgesic use, or sinus track. Twelve studies were included in the review. No detectable difference was found in the effectiveness of root canal treatment in terms of radiologic success between single and multiple visits. Neither single-visit root canal treatment nor multiple-visit root canal treatment can prevent 100% of short-term and long-term complications. Patients undergoing a single visit might experience a slightly higher frequency of swelling and refer significantly more analgesic use.

Before you pee on yourself out of excitement that the above study might provide some validation that single-visit root canal treatment in infected teeth offers the same therapeutic outcome as multi-visit treatment, realize a couple of things:

1. Double-blind randomized studies are rare in endodontic research, as are studies with adequate statistical power². A meta-analysis can only be as significant as the weakest study it includes.
2. Proper evaluation of endodontic healing based on radiographic changes is not appropriate after only 1 year. Strindberg³ showed this a long time ago, and so did Orstavik⁴ more recently.

1. Figini L, Lodi G, Gorni F, Gagliani M. Single versus multiple visits for endodontic treatment of permanent teeth. Cochrane Database Syst Rev. 2007 Oct 17;(4):CD005296. [↩]
2. Trope M, Delano EO, Orstavik D. Endodontic treatment of teeth with apical periodontitis: single vs. multivisit treatment. J Endod. 1999 May;25(5):345-50. [↩]
3. Strindberg LZ (1956). The dependence of the results of pulp therapy on certain factors. An analytic study based on radiographic and clinical follow-up examinations. Acta Odontol Scand 14(Suppl 21):1–175. [↩]
4. Orstavik D. Time-course and risk analyses of the development and healing of chronic apical periodontitis in man. Int Endod J. 1996 May;29(3):150-5. [↩]