The effect of biologic factors and adjunctive therapies on orthodontically induced inflammatory root resorption: a systematic review and meta-analysis.

Objective: Biologic factors and adjunctive therapies are known to affect the degree of orthodontically induced inflammatory root resorption (OIIRR). However, a systematic overall assessment of their impact on OIIRR has not previously been reported. We, therefore, aimed to systematically assess effects on OIIRR of biologic factors and adjunctive therapies in human and animal subjects.

Methods: A comprehensive search strategy was performed for all major electronic databases. Two reviewers independently selected studies, undertook data extraction and assessed the risk of bias for all included studies according to a pre-specified protocol inspired by Cochrane and the PRISMA guidelines. Eligible studies compared the effect of intervention(s) in an experimental and a control group.

Results: A total of 9 human and 36 animal trials met the inclusion criteria. Where appropriate, random-effect meta-analyses were carried out to determine the outcome measure OIIRR. The random-effect meta-analysis demonstrated that OIIRR was inhibited by fluoride (ES = -2.08 [-3.02, -1.14]), thyroxine (ES = -1.91 [-3.20, -0.61]), and steroids (ES = -2.79 [-4.26, -1.33]). In contrast, corticotomy (ES = 0.38 [0.05, 0.71]) significantly enhanced OIIRR.

Conclusion: In animals, administration of fluoride, thyroxine and steroids decreased OIIRR, whereas corticotomy increased OIIRR. In general, the effect on OIIRR increased with higher dosage and/or exposure time. Despite methodological limitations of the included studies, this systematic review provides an important overview of the effect of biologic factors and adjunctive therapies on OIIRR.