Six-year post-surgical evaluation in the treatment protocols in the dental arches of children with oral cleft: longitudinal study

Abstract Oral cleft surgical repairs are performed using different techniques worldwide. Objective To evaluate and compare the development of the dental arches of children with unilateral cleft lip and palate before and after the primary surgeries performed with different techniques at the first months and six years of life. Methodology This is a retrospective longitudinal study. The sample comprised 56 dental casts divided int the following groups: Group 1 (G1) – cheiloplasty (Millard technique) at three months and one-step palatoplasty (von Langenbeck technique) at 12 months; and Group 2 (G2) – cheiloplasty (Millard technique) and two-step palatoplasty: anterior hard palate closure (Hans Pichler technique) at three months and posterior soft palate closure (Sommerlad technique) at 12 months. The digitized dental casts were evaluated at three months – pre-surgical (T1) and six years of life– post-surgical (T2). The following linear measurements were analyzed: intercanine (C–C’), intertuberosity (T–T’) distances; anterior dental arch (I–CC’), anterior intersegment (I–C’), and total arch (I–TT’) lengths. The palate area was also measured. Parametric and non-parametric tests were applied (p<0.05). Results In G1, the intragroup comparison showed statistically significant smaller I–CC’ and I–C’ at T2 (p=0.001 and p<0.001, respectively), while T–T’, I–TT’, and area comparisons were significantly greater (p<0.001, p=0.002, and p<0.001, respectively). In G2, the intragroup comparison exhibited statistically significant smaller C–C’ and I–C’ at T2 (p=0.004, for both), whereas T–T’, I–TT’ and area comparisons were significantly greater (p<0.001, p=0.004, and p<0.001, respectively). At T2, the intergroup analysis revealed that G1 had a statistically significant smaller I–CC’ (p=0.014). The analysis of the intergroup differences (∆=T2–T1) showed that G1 had a statistically smaller I–CC’ (p=0.043). Conclusion The two-step palatoplasty showed a more favorable prognosis for the maxillary growth than one-step palatoplasty in children with oral clefts.


Introduction
Cleft lip and palate (CLP) is the malformation most common diagnosed in the craniofacial region of the humans. CLP etiology is complex due to multifactorial factors such as genetic 1,2 and environment 2 , bringing an abnormal facial development during embryogenesis. This is associated to severe development anomalies of the hard and soft tissues. The maxillary growth disturbance is typical in individuals with cleft lip and palate, probably due to the lack of maxillary growth caused by the healing of the lip and/or palate repair. 3,4 Children with CLP require multidisciplinary treatment since they show problems with dental anomalies, esthetics, hearing and speech impairment, and mainly, psychosocial behavior. 1,2 Thousands of CLP surgical repairs are performed annually through different techniques worldwide. However, the literature lacks studies on the comparison of the outcomes of these different repair techniques. Each rehabilitation center treats CLP with different surgical approaches, 4,5 with and without presurgical orthopedics 2,6,7 , different time and techniques of primary surgeries, 2,7,8 alveolar bone graft with different materials 9 , and surgeon techniques and experience. 10,11 In this context, cheiloplasty (lip surgical repair) is frequently performed in either newborns during the first week of life or in babies between 3 and 6 months of life. Palatoplasty (palate surgical repair), in turn, is performed between 12 and 18 months of age. 3,12 The repair aims to restore the normal morphology and the function, with the minimum of disturbance of the maxillary growth potential. 7  2.32 mm for the total dental arch length at pre-surgical stage, with 5% significance level, 80% power test, and minimum difference to be clinically detected of 2.7 mm. The minimum sample size of each group was of 14 children. distance T-T'. 6,10,12,17,18 All linear measurements were analyzed in millimeters (mm) (Figures 2A and 3A).
The dental arch area was analyzed in squared millimeters (mm²). At T1, the area was marked by

Intergroup analyses
At T2, the intergroup analysis revealed that G1 had a statistically significant smaller I-CC' mean than that of G2 (p=0.014) ( Table 3).

Discussion
The treatment protocols evaluated in our study were performed by a single plastic surgeon with 35 years of experience in cheiloplasty and palatoplasty surgeries in individuals with orofacial clefts. This is very relevant criteria since the outcomes obtained  The dental arches of children with cleft lip and palate were evaluated at the first months of life and at six years of age because the literature lacks studies on evaluating the maxillary growth before the onset of the permanent dentition. Most of the longitudinal studies evaluated the maxillary changes 12-24 months after the lip and palate repair surgeries. 6,10,14,[19][20][21] Other studies did measure the dental arch area of children with clefts, but they did not follow the maxillary growth until five years of age. 10,14,[22][23][24][25] Our study revealed that children subjected to two-step palate repair had better growth than those subjected to one-step palatoplasty.
The changes observed led to rejection of hypothesis   One-step palatoplasty (G1) showed more reduction in the anterior arch length after lip and full palate repair. This was similar to the results of the study of Haque, et al. 4 (2020) who affirmed that in children with unilateral CLP the maxillary constriction is the main disadvantage of the standard palatoplasty procedure. Two-step palatoplasty (G2) exhibited a smaller reduction in both the anterior arch length and anterior transversal arch length.
In both groups, cheiloplasty at 3 months of age had a restrictive effect on both anterior arch length and anterior transversal arch length. This result was similar to those reported by Haque, et al. 4 (2020), who performed different surgical techniques that inhibited the maxillary growth, especially on the anterior segment. Girinon, et al. 26 (2019) hypothesized that cheiloplasty at six months of age would enable a better anatomic reconstruction than at three months.
However, further studies are necessary to prove this hypothesis. Other studies on linear measurements revealed that the maxillary anterior area of individuals with unilateral CLP underwent transversal restriction after cheiloplasty using the decreasing of the intercanine distance, but showing and increasing of the intertuberosity distance; after palatoplasty, these distances were maintained stable. 6,20,27,28 At the six-year-old post-surgical evaluation, G1 had a more restrictive effect on the anterior arch length than G2, corroborating the results of the studies of Haque andAlam 29 (2015), andGirinon, et al. 26 (2019), in which individuals subjected to twostep palatoplasty showed better maxillary growth, that is, one-step palatoplasty was less favorable than two-step palatoplasty. Different results showed similar maxillary deficiency in individuals subjected to lip repair compared to those subjected to lip and palate repair. 30 Yu,et al. 31 (2020)  It is difficult to obtain dental casts of newborns because of the affliction and agitation of the baby during the impression procedure. 33 Moreover, dental cast may have defect as bubbles and poorly finishing that confuse landmark, so they were eliminated of the sample. Despite these limitations, the impression procedure of newborns is the gold standard for the documentation of children with CLP. In the future, intraoral scanning could replace the impressions, but the current scanning device tips are still too big to be used inside the babies' mouths. In this study, the software used showed good reproducibility to determine the maxillary growth.

Conclusion
Based on the results, this study showed that twostep palatoplasty was a more favorable prognosis for the maxillary growth than one-step palatoplasty in children with oral clefts.