Clinical efficacy of lip repositioning technique and its modifications for the treatment of gummy smile: systematic review and meta-analysis

Objective To systematically review the literature regarding the clinical efficacy of reducing excessive gingival display (EGD) using the surgical lip repositioning technique (LRT) and its modifications. The question to address was: "What is the clinical efficacy of the surgical LRT and its modifications in patients with EGD?" Material and methods Four databases (MEDLINE-PubMed, Scopus, EMBASE, and CENTRAL) were searched up to December 2021 (PROSPERO-CRD42020205987). Randomized, non-randomized controlled and prospective case series with a minimum of 6-month follow-up were eligible for inclusion. Two meta-analyses were performed using the mean difference (MD) between baseline and different follow-up periods (6 and 12 months). Subgroup analyses were performed using the different modifications of LRT. Results The electronic research retrieved 783 studies. Only 13 met the inclusion criteria and were included in the statistical analysis. Six modifications of the original LRT were identified. An overall EGD reduction of -3.06 mm (95%CI: -3.71-2.40), -2.91 mm; (95%CI: -3.66-2.15) and -2.76 mm; (95%CI: -3.83--1.70) was achieved after 6, 12, and 36 months, respectively, compared to baseline (P < 0.01). Meta-analysis revealed that the use of LRT with periosteal suturing showed the greatest decrease in EGD with 5.22 mm (95% CI: 4.23-6.21; P < 0.01) at 6 months and 4.94 mm (95% CI: 3.86-6.02; P < 0.01) at 12 months. Conclusions Both the original LRT and its different modifications reduce EGD and provide good results and overall patient satisfaction at 6, 12, and 36 months of follow-up.