Introduction and objective:
Non-carious cervical lesions (NCCLs) are a very interesting topic in the field of restorative dentistry. This is for several reasons: (1) It considered one of the most common lesions in the permanent teeth. (2) The best restorative materials indicated for NCCLs is still a controversial subject, and (3) despite many studies done and still ongoing, there are no consensuses about bonding agent systems and their bounding effectiveness.
Currently, the restorative options for cervical lesions (in general) are composite resin, glass ionomer, gold foil, and amalgam. Each of these options have different characteristics and properties. For example, gold foil is one of the best dental materials with respect to the physical properties; however, for conservative and esthetic reasons, composite is one of the best restorative dental materials. Glass ionomer comes after composite as an esthetic direct restorative material. Besides this, glass ionomer uniquely has an anti-carious property by releasing fluoride ions. In advanced NCCLs, since the tooth already lost part of its structure, it is preferred to restore these cases with restorations that do not require further preparation for retention like composite resin and glass ionomer. Consequently, composite and glass ionomer are favored over amalgam and gold foil for esthetic and conservative purposes in NCCLs cases. Hence, in this study, we want to compare composite resin and glass ionomer as a restoration option for non-carious cervical lesions (NCCLs). More specifically, we want to evaluate the marginal integrity and retention rate of composite resin and glass ionomer materials as a restoration option for NCCLs.
The aim of this study is to sum up the evidence from multiple systematic reviews, clinical trials, and observational studies that have evaluated the marginal integrity of resin composite and glass ionomer restorations placed in non-carious cervical lesions. In other words, our purpose is to compare glass ionomer and resin composite as restoration for non-carious cervical lesions using an evidence based dentistry approach by going through the Comparative Effectiveness and Efficacy Research and Analysis for Practice (CEERAP) in order to find out which one of these two materials has better marginal integrity.
Systematic reviews with or without meta-analysis, observational studies, and randomized clinical trials that assess the effectiveness of glass ionomer, composite resin, and/or adhesive systems, such as a restorative material for NCCLs were chosen. Cochrane library, PubMed, ADA Center for Evidence-Based Dentistry, Google Scholar, Web of Science databases were searched from September 2015 to April 2016. The review was restricted to papers with English language and papers studying permanent teeth with a time frame of no less than one year.
Three clinical trials and three systematic reviews have been accepted as papers with a high level quality of evidence. All of the accepted clinical trials concluded that glass ionomers have better marginal integrity than resin composite in the NCCLs. On the other hand, two of the systematic reviews agreed with our clinical trials- that glass ionomers as a restoration for NCCLs would have better marginal integrity than resin composite. Only one systematic review concluded that resin composite as a restoration for NCCLs has better marginal integrity than glass ionomer.
There is a consensus that NCCLs are a multifactorial lesion, caused by abrasive-erosive-ablative stress; hence the resulting dentine is a hyper-mineralized sclerotic dentine with partial or total obliteration of the tubules. The sclerotic dentine phenomenon is shown in Figure (1), which negatively affects dentine bonding. Malocclusion and/or eccentric movements might contribute in initiating or worsening NCCLs. Flexure at the cervical region caused by parafunctional forces has been thought to be one of the etiological factors in NCCLs as well.
Unlike teeth with normal dentine, restoring teeth with sclerotic dentine by composite resin is unpredictable because sclerotic dentine differs anatomically and may need to be etched differently than sound dentin. Consequently, retention, marginal integrity, recurrent caries, micro-leakage, or sensitivity issues are usually shown in NCCLs restored with resin composite.
Key words: Composite - Glass ionomer - NCCLs - Bonding - retention - Marginal discoloration - Marginal integrity.