Establishing the association between nonnutritive sucking behavior and malocclusions A systematic review and meta-analysis

Background. The authors studied the effects of nonnutritive sucking behavior (NNSB) on malocclusions through a systematic review of association (etiology). Types of Studies Reviewed. The authors performed a 3-step search strategy, including electronic searches. Studies of healthy participants with a history of active or previous NNSB, for whom specific malocclusion outcomes had been assessed, were eligible for inclusion. The authors considered before-and-after studies, prospective and retrospective (longitudinal) studies, case-control studies, and analytical cross-sectional studies. They excluded reviews, text- and opinion-based articles, conference abstracts, case reports, case-series, and descriptive cross-sectional studies. The authors, using standardized instruments, independently assessed methodological quality and extracted data from the included studies. In situations for which there were sufficient studies, the authors conducted meta-analyses using the random-effects model, supplemented with the fixed-effects model in situations for which statistical heterogeneity was less than 50%, which the authors assessed using the I-2 statistic. Results. The authors included 15 identified studies. They found that NNSB was associated with varying risks of developing malocclusions. Pacifier suckers are less likely to develop an increased overjet compared with digit suckers, although the results of a meta-analysis of 7 studies whose investigators had assessed posterior crossbite in the primary dentition demonstrated a significant association with pacifier sucking over digit sucking (n = 5,560; risk ratio, 1.42; 95% confidence interval, 1.18-1.70; P = .0001). Longer duration of NNSB was associated with an increased risk of developing malocclusions. Across-study heterogeneity likely resulted from methodological and sample size differences. Conclusions. The authors of this study have confirmed the association between NNSB and the development of malocclusions. This study provides the highest level of evidence on this topic. Pacifiers were associated with a higher risk of developing most malocclusion features when compared with digit sucking. Practical Implications. Though malocclusions are of multifactorial etiology, clinicians should inform parents and caregivers about the dental risks of NNSB, an environmental factor that is modifiable. NNSB should be discouraged in order to avoid the development of malocclusions. Future studies should adopt standardized, universally agreed and accepted definitions and classifications when measuring and reporting orthodontic outcome measures. This will help achieve across-study homogeneity.