Reviews Systematic and Meta-analysis

Systematic reviews are increasingly used in dentistry and have expanded from mainly synthesizing interventional trials to observational studies. Systematic review denotes a type of scientific study that seeks to gather and examine all studies carried out on a specific question in order to provide an unbiased summary of the evidence, following a predefined, comprehensive and objective approach. Systematic reviews need to address bias in the included studies and are oftentimes subject to bias themselves, which should be considered during their planning and conduct. Systematic reviews should further address statistical, methodological and clinical heterogeneity. Besides qualitative synthesis, meta-analysis and network meta-analysis are often used to synthesize data. Further exploration of subgroup effects of confounding variables via meta-regression can be useful but needs careful planning. The possibility to compare multiple groups within or among studies, a network meta-analysis has shown to be a very useful statistical technique. Results of systematic reviews are further applied in health economics and implementation research.