Mojtaba Dorri, Stephen M Dunne, Tanya Walsh, Falk Schwendicke

Proximal dental lesions, limited to dentine, are traditionally treated by invasive (drill and fill) means. Non-invasive alternatives (e.g. fluoride varnish, flossing) might avoid substance loss but their effectiveness depends on patients' adherence. Recently, micro-invasive approaches for treating proximal caries lesions have been tried. These interventions install a barrier either on top (sealing) or within (infiltrating) the lesion. Different methods and materials are currently available for micro-invasive treatments, such as sealing via resin sealants, (polyurethane) patches/tapes, glass ionomer cements (GIC) or resin infiltration. To evaluate the effects of micro-invasive treatments for managing proximal caries lesions in primary and permanent dentition in children and adults. We searched the following databases to 31 December 2014: the Cochrane Oral Health Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE via OVID, EMBASE via OVID, LILACs via BIREME Virtual Health Library, Web of Science Conference Proceedings, ZETOC Conference Proceedings, Proquest Dissertations and Theses, ClinicalTrials.gov, OpenGrey and the World Health Organization (WHO) International Clinical Trials Registry Platform. We searched the metaRegister of Controlled Trials to 1 October 2014. There were no language or date restrictions in the searches of the electronic databases. We included randomised controlled trials of at least six months' duration that compared micro-invasive treatments for managing non-cavitated proximal dental decay in primary teeth, permanent teeth or both, versus non-invasive measures, invasive means, no intervention or placebo. We also included studies that compared different types of micro-invasive treatments. Two review authors independently screened search results, extracted data and assessed the risk of bias. We used standard methodological procedures expected by Cochrane to evaluate risk of bias and synthesise data. We conducted meta-analyses with the random-effects model, using the Becker-Balagtas method to calculate the odds ratio (OR) for lesion progression. We assessed the quality of the evidence using GRADE methods. We included eight trials, which randomised 365 participants. The trials all used a split-mouth design, some with more than one pair of lesions treated within the same participant. Studies took place in university or dental public health clinics in Brazil, Colombia, Denmark, Germany, Thailand, Greenland and Chile. Six studies evaluated the effects of micro-invasive treatments in the permanent dentition and two studies on the primary dentition, with caries risk ranging from low to high. Investigators measured caries risk in different studies either by caries experience alone or by using the Cariogram programme, which combines eight contributing factors, including caries experience, diet, saliva and other factors related to caries. The follow-up period in the trials ranged from one to three years. All studies used lesion progression as the primary outcome, evaluating it by different methods of reading radiographs. Four studies received industry support to carry out the research, with one of them being carried out by inventors of the intervention.We judged seven studies to be at high overall risk of bias, primarily due to lack of blinding of participants and personnel. We evaluated intervention effects for all micro-invasive therapies and analysed subgroups according to the different treatment methods reported in the included studies.Our meta-analysis, which pooled the most sensitive set of data (in terms of measurement method) from studies presenting data in a format suitable for meta-analysis, showed that micro-invasive treatment significantly reduced the odds of lesion progression compared with non-invasive treatment (e.g fluoride varnish) or oral hygiene advice (e.g to floss) (OR 0.24, 95% CI 0.14 to 0.41; 602 lesions; seven studies; I(2) = 32%). There was no evidence of subgroup differences (P = 0.36).The four studies that measured adverse events reported no adverse events after micro-invasive treatment. Most studies did not report on any further outcomes.We assessed the quality of evidence for micro-invasive treatments as moderate. It remains unclear which micro-invasive treatment is more advantageous, or if certain clinical conditions or patient characteristics are better suited for micro-invasive treatments than others. The available evidence shows that micro-invasive treatment of proximal caries lesions arrests non-cavitated enamel and initial dentinal lesions (limited to outer third of dentine, based on radiograph) and is significantly more effective than non-invasive professional treatment (e.g. fluoride varnish) or advice (e.g. to floss). We can be moderately confident that further research is unlikely to substantially change the estimate of effect. Due to the small number of studies, it does remain unclear which micro-invasive technique offers the greatest benefit, or whether the effects of micro-invasive treatment confer greater or lesser benefit according to different clinical or patient considerations.