Effects of lip bumper therapy on the mandibular arch dimensions of children and adolescents: A systematic review.

INTRODUCTION: The aim of this systematic review was to identify, evaluate, and provide a synthesis of the available literature on the effects of lip bumper (LB) therapy on the mandibular dental arch of children and adolescents. METHODS: MEDLINE, Scopus, Web of Science, Cochrane Library, and Lilacs were systematically searched without restrictions up to May 2019. Risk-of-bias assessment was performed using Cochrane's tool for randomized controlled trials (RCTs) and the Risk of Bias in Nonrandomized Studies of Interventions tool for non-RCTs. The Grading of Recommendations, Assessment, Development and Evaluation tool was used to assess the quality of the evidence. RESULTS: After examination of the full texts, 6 studies were included. One RCT presented unclear risk of bias, and 5 non-RCTs presented serious to moderate risk of bias. LB therapy resulted in a buccal inclination of the incisors, distalization of the permanent first molars, and distal inclination of the permanent first molars, which increased perimeter and arch length. An increase in the arch width with greater gain in the interpremolar and/or deciduous molar distance and less gain in intercanine and intermolar distances was also reported. LB therapy increased the risk of second molar impaction with inclination >30° and the risk of ectopic eruption when treatment time was >2 years. The level of the evidence was graded as very low for variable arch length and second molar eruption disturbances. All other outcomes were graded as having low level of evidence. CONCLUSIONS: Owing to the low level of certainty identified, the conclusions should be considered cautiously. Increase in arch perimeter and width was attributed to the proclination of the incisors, buccalization of the deciduous molar and premolar areas, and distal inclination of the molars. However, there was an increased chance of impaction and ectopic eruption of permanent second molar after treatment with LB.