Effect of maxillary distraction osteogenesis and LeFort-1 advancement orthognathic surgery on soft-tissue thickness and anterior soft-tissue to hard-tissue movement ratios among patients with complete unilateral cleft lip and palate

Abstract

Objectives: The objective of this study was to compare the soft-tissue thickness and anterior soft-tissue to hard-tissue movement ratios in patients with unilateral cleft lip and/or palate (UCLP) following maxillary distraction osteogenesis using rigid external distractor device and maxillary advancement at LeFort I level using lateral cephalograms. Material and Methods: This retrospective study was conducted on 20 patients with UCLP who underwent either LeFort I maxillary advancement or maxillary distraction osteogenesis. Non-syndromic patients with complete UCLP anomalies and skeletal class III patterns due to maxillary hypoplasia were included in the study. The patients with a pre-surgical negative overjet of ≥5 mm were treated by maxillary distraction osteogenesis, while a negative overjet of <5 mm was managed with maxillary advancement orthognathic surgery. The growth completion in all the patients was assessed using the cervical vertebrae maturation index (CS 6) on a lateral cephalogram. The lateral cephalograms taken before surgery at (T0) and after a minimum interval of six months (T1) of surgery were assessed for changes in soft-tissue thickness and hard-tissue to soft-tissue movement ratios among the two groups. Paired t-test was used to compare the mean values obtained within the same group at two different time intervals. Unpaired t-test was used to compare mean values between the Groups 1 and 2. Pearson’s correlation coefficient (r) test was used to assess the associations between the mean changes in hard- and soft-tissue variables. Results: Group 1 showed significantly greater maxillary advancement compared to Group 2 with a mean difference of 5.80 mm at Point A and 7.65 mm at the upper incisal edge. Soft-tissue thickness decreased significantly after advancement in Group 1 at subnasale (P < 0.05), labrale superius, stomion, and labrale inferius (P < 0.01) and at subnasale (P < 0.05), stomion and labrale inferius (P < 0.01) in Group 2. There was a significantly strong correlation between the hard- and soft-tissue movement in sagittal plane in both Group 1 and Group 2. In Groups 1 and 2, a statistical highly significant strong positive correlation was found between vertical change in dU1 to soft-tissue dLs and dStms. In Group 2, a statistical highly significant strong positive correlation was found between vertical change in dA to soft-tissue dC and dStms. Conclusion: The soft-tissue thickness reduced in patients with UCLP after maxillary advancement in both groups. The soft tissue followed the hard tissue in both groups. There was a greater downward movement of the maxillary base and soft-tissue lengthening in Group 1 compared to Group 2.