N oncarious cervical lesions (NCCLs) are pathological processes of dental wear of multifac- torial etiology indepen- dent of bacteria. They are classified according to etiology as erosion, abrasion/corrosion or abfraction. However, because different etiologic factors may act together to promote the same lesion, the cause of these lesions may be multifactorial. 1-5 These lesions can occur in young patients and become more frequent as the patient ages. The prevalence of such lesions is high in premolars, and the shape of the lesion reflects the factors that contributed to its formation. 6 Some authors suggest that occlusal load plays a primary role in the development of NCCLs. 7,8 According to the theory of dental flexure, masticatory or abnormal loads, when applied in areas of hyperfunction or malocclusion, may expose one or more teeth to an extreme force. This force focuses on the cementoenamel junction (CEJ), where it can cause microfractures in enamel and dentin. These micro- Dr. Luciana Francisconi is a doctoral student, Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Dr. Octávio Pinheiro Brisolla, 9-75, P.O. Box 73, Bauru, São Paulo 17012-901, Brazil, e-mail “luff@usp.br”. Address reprint requests to Dr. Francisconi. Ms. Graeff is a laboratory specialist, Integrated Research Center, Bauru School of Dentistry, University of São Paulo. Dr. Martins is a doctoral student, Department of Oral Rehabilitation, Bauru School of Dentistry, University of São Paulo. Dr. Franco is a full professor, Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo. Dr. Mondelli is an associate professor, Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo. Dr. Paulo Francisconi is an associate professor, Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo. Dr. Pereira is a full professor, Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo. The effects of occlusal loading on the margins of cervical restorations Luciana Fávaro Francisconi, DDS, MS, PhD Candidate; Márcia Sirlene Zardin Graeff, MS; Leandro de Moura Martins, DDS, MS, PhD Candidate; Eduardo Batista Franco, DDS, MS, PhD; Rafael Francisco Lia Mondelli, DDS, MS, PhD; Paulo Afonso Silveira Francisconi, DDS, MS, PhD; José Carlos Pereira, DDS, MS, PhD JADA, Vol. 140 http://jada.ada.org October 2009 1275 Background. Researchers have proposed the restoration of abfraction lesions, but limited information is available about the effects of occlusal loading on the margins of such restorations. Because abfraction is a well- recognized problem, the authors conducted a study to assess the effects of occlusal loading on the margins of cervical restorations. Methods. The authors prepared 40 wedge-shaped cavities in extracted premolars and restored them with a resin-based composite. They sub- jected specimens to occlusal loading (150 newtons, 10 6 cycles) on the buccal cusp, on the central fossa or on the lingual cusp, and they stored the control group specimens in deionized water. The authors used fluo- rescein to delimit marginal defects and evaluated the defects by using laser scanning confocal microscopy. Results. Results of χ 2 and Kruskal-Wallis tests (P < .05) showed that specimens subjected to occlusal loading had a higher percentage of mar- ginal gaps (53.3 percent) than did the control specimens (10.0 percent). There were no differences between groups in marginal defect formation or in defect location, length or width. Conclusions. Occlusal loading led to a significant increase in gap for- mation at the margins of cervical resin-based composite restorations. Clinical Implications. The clinician cannot underestimate the effects of occlusal loading when restoring teeth with cervical wedge- shaped lesions. If occlusal loading is the main factor contributing to lesion formation, the clinician should identify and treat it before placing the res- toration or otherwise run the risk that the restorative treatment will fail because of marginal gap formation. Key Words. Cervical restorations; occlusal loading; marginal adapta- tion; confocal microscopy. JADA 2009;140(10):1275-1282. ABSTRACT R E S E A R C H Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.