Volume 39, Issue 10 , Pages 956-961, October 2010
Cleft size at the time of palate repair in complete unilateral cleft lip and palate as an indicator of maxillary growth
Article Outline
Abstract
Cleft size at the time of palate repair might affect the difficulty of surgical repair and, thus, indirectly postoperative maxillary growth. This retrospective study aimed to determine whether a correlation existed between the cleft size at the time of palate repair and the growth of the maxilla. Maxillary dental casts of 39 infants with non-syndromic complete unilateral cleft lip and palate, taken at the time of palate repair, were used to measure cleft size. Cleft size was defined as the percentage of the total palatal area. The later growth of the maxilla was determined using lateral and postero-anterior cephalometric radiographs taken at 9 years of age. The Pearson correlation analysis was used for statistical analysis. The results showed negative correlations between cleft size and the maxillary length (PMP–ANS, PMP–A) and the maxillary protrusion (S–N–ANS, SNA). These data suggest that in patients with complete unilateral cleft lip and palate there is a significant correlation between the cleft size at the time of palate repair and the maxillary length and protrusion. Patients with a large cleft at the time of palate repair have a shorter and more retrusive maxilla than those with a small cleft by the age of 9 years.
Keywords: cleft size, maxillary growth, palate repair, treatment outcome, unilateral cleft lip and palate
Patients who have undergone surgery for cleft lip and palate often suffer from maxillary retrusion. Much of the anteroposterior growth disturbance of the maxilla results from the surgical procedure. The surgical procedure with the greatest inhibiting effect on maxillary growth is almost certainly palate repair16, 17, 18, 19, 25. The idea that palate repair is detrimental to maxillary growth originates with the clinical observation of Gilles & Fry7 and the experimental and clinical works of Herfert8. Herfert is the first to suggest that the nature of palate repair, which includes raising a palatal mucoperiosteal flap, affects the growth centres of the hard palate and leads to aberrations of maxillary growth8. Whether the apparent adverse effects of palate repair on maxillary growth are due to de-vascularization, disturbance of periosteum, or the restrictive effect of the scar, has been debated. In general, the idea of a reduced blood supply to the maxillary skeleton after palate repair has not been accepted. One popular theory of abnormal maxillary growth following palate repair in patients with cleft palate, proposed by Ross24, is that excessive postoperative scar tissue, formed by undermining soft tissues and the creation of denuded palatal bone, adjacent to the pterygo-palatine-tuberosity sutures can inhibit the forward growth of the maxilla.
At the time of palate repair, a common problem encountered by the cleft surgeon is insufficient tissue (i.e. large cleft). Cleft size might affect the difficulty of surgical repair and, thus, indirectly postoperative maxillary growth. The authors hypothesized that there is an influence of cleft size at the time of palate repair on maxillary growth.
Methods
Patients were selected from the growth archive of Chang Gung Craniofacial Center, Taipei, Taiwan using the following criteria: Taiwanese patients with non-syndromic complete unilateral cleft lip and palate (UCLP), in whom the diagnosis had been confirmed by neonatal photographs or a chart description written by a plastic surgeon or clinical geneticist; those born between 1991 and 1995 and treated at the Center; passive infant orthopedics (i.e. infant plate) prior to lip repair; modified rotation-advancement lip repair at 3–6 months of age by one senior surgeon (PKTC); maxillary dental casts taken at the time of palate repair; one-stage two-flap palatoplasty at about 1 year of age by the same surgeon; cephalometric assessment at about 9 years of age; and no other bony surgery or orthodontic treatment before cephalometric assessment. Thirty-nine patients met the selection criteria.
Cleft size
Cleft size data were obtained from infant maxillary dental casts using a photographic method by one investigator (NKKP). Prior to photographing, the outlines of the palate as well as the cleft were traced with a light pencil by one investigator. The outline of the palate was traced, following the alveolar crest, across the alveolar cleft anteriorly, and posteriorly the inter-tuberosity line. The outline of the cleft was traced, following the line of the alveolar crest anteriorly and the inter-tuberosity line posteriorly. The dental casts were placed on an adjustable jig with the alveolar crest parallel to the floor. All the casts were photographed on the same occasion, and the images were stored in the Microsoft ACDSee software as JPEG files (Fig. 1). Once the photograph was taken, the tracing lines were erased immediately to eliminate possible bias for the next measurement. Both the areas of the palate and cleft were measured using Image J freeware from the National Institutes of Health (http://rsb.info.nih.gov/ij). The total palatal area was calculated as the sum of the cleft area and the palatal area. The cleft size was calculated as the percentage of the total palatal area. Two weeks later, the dental casts were retraced, re-photographed and re-measured by the same investigator under the same condition. The average area values for each patient were calculated from the duplicate measurements.
Fig. 1.
Measurement of the areas of the palate and cleft on the dental cast. A
+B=palatal area; C=cleft area; A+B+C=total palatal area; C×100/A+B+C=cleft size.
Cephalometry
Cephalometric radiographs were obtained using the same cephalostat with the natural head position and with the teeth in centric occlusion. The radiographs were traced by one investigator (NKKP) and verified by a senior orthodontist (YFL) blinded to the patient's cleft size. Fig. 2, Fig. 3 illustrate the landmarks, reference lines or planes used in the study. The cephalometric variables were classified into 5 categories: cranial base data; maxilla data; mandible data; jaw relation data; and face height data.
Fig. 2.
Landmarks and reference lines or planes used on a lateral cephalometric radiograph. A, A point; ANS, anterior nasal spine; Ar, articulare; B, B point; Ba, basion; Gn, gnathion; Go, gonion; GoI, gonion intersection, the intersection of the MP and RL; Men, menton; MP, mandibular plane, a line from Men tangent to the posteroinferior border of the mandible; N, nasion; PMP, posterior maxillary point, a construct created by dropping a perpendicular to the line from ANS passing through posterior hard palate from PTM; PP, palatal plane, a line through PMP and ANS; Pog, pogonion; PTM, pterygo-maxillary fissure; R, registration point, point of crossing of the greater wing of sphenoid and planum sphenoidale; RL, ramus line, a line from Ar tangent to the posteroinferior border of the mandible; S, sella turcica; SN, sella-nasion line.
Fig. 3.
Landmarks used on a postero-anterior cephalometric radiograph. J, jugular point (′ denotes cleft side).
Statistical analysis
Data were expressed as means and SDs. Bivariate correlation analysis using Spearman's or Pearson's correlation coefficient was used when indicated to find the variables correlated with cleft size. Statistical analyses were carried out using SPSS v 12.0 (Chicago, IL, USA). The statistical significance level selected for all analyses was P≤0.05.
Results
Clinical, dental cast and cephalometric variables of the study group are shown in Table 1. Thirty-nine patients (67% boys, 93% left-sided cleft) had a mean cleft size of 18.6±5.4% ranging from 6% to 29%. Table 2 reports the correlation coefficients of cleft size and clinical, dental cast, and craniofacial variables. Cleft size was highly correlated with gender (r=−0.42, P=0.009), cleft area (r=0.93, P<0.001) and palatal area (r=−0.35, P=0.03). Correlation of cleft size with craniofacial variables indicated a higher linear relationship with N–S–Ba (r=0.42, P=0.008), maxillary length (PMP–ANS: r=−0.56, P<0.001; PMP–A: r=−0.55, P<0.001), maxillary protrusion (S–N–ANS: r=−0.33, P=0.04; SNA: r=−0.38, P=0.02), R–PMP (r=−0.31, P=0.05), SN–PP (r=0.30, p=0.04), S–Go (r=−0.4, P=0.01) and a near significant relationship with ANB (r=−0.3, P=0.06). No relationships were found between cleft size and other craniofacial data.
Table 1. Clinical, dental cast and cephalometric data for patients.
| Mean | SD | Range | |
|---|---|---|---|
| Age at dental cast, yr | 1.0 | 0.04 | 1.0–1.1 |
| Age at cephalometry, yr | 9.3 | 0.7 | 8.5–11.0 |
| Cleft area, mm2 | 187.8 | 64.7 | 67–317 |
| Palatal area, mm2 | 815.3 | 102.9 | 580–999 |
| Total palatal area, mm2 | 1003.1 | 121.4 | 745–1276 |
| Cleft sizea, % | 18.6 | 5.4 | 6–29 |
| S–N, mm | 66.1 | 3.5 | 58–73 |
| S–Ba, mm | 46.1 | 2.6 | 40–54 |
| N–S–Ba,° | 130.8 | 4.3 | 120–141 |
| Ba–PMP, mm | 42.5 | 3.3 | 34–50 |
| PMP–ANS, mm | 45.7 | 2.8 | 39–51 |
| PMP–A, mm | 43.3 | 2.9 | 37–50 |
| S–N–ANS,° | 79.4 | 4.2 | 70–88 |
| SNA,° | 76.7 | 3.8 | 68–85 |
| N–ANS, mm | 49.4 | 3.5 | 41–56 |
| R–PMP, mm | 42.5 | 3.6 | 36–50 |
| SN–PP,° | 9.7 | 3.9 | 4–21 |
| Ar–Go, mm | 40.5 | 3.3 | 31–46 |
| Go–Gn, mm | 70.0 | 4.6 | 59–81 |
| Ar–Gn, mm | 98.6 | 6.2 | 84–115 |
| SNB,° | 76.7 | 3.4 | 67–83 |
| S–N–Pog,° | 76.2 | 3.4 | 67–84 |
| SN–MP,° | 34.6 | 4.6 | 24–49 |
| Ar–Go–Gn,° | 124.3 | 4.7 | 114–132 |
| ANS–N–Pog,° | 3.2 | 4.0 | −5 to 14 |
| ANB,° | 0 | 3.3 | −8 to 2 |
| N–Men, mm | 113.8 | 5.7 | 98–123 |
| S–Go, mm | 71.1 | 4.0 | 63–81 |
| J–J′, mm | 68.2 | 4.2 | 58–76 |
Table 2. Correlation coefficients of relationships between cleft size and clinical, dental cast and craniofacial variables.
| Variable | Cleft size (percentage cleft area/total palatal area) | |
|---|---|---|
| r | P-value | |
| Gender, n | −0.42 | 0.009 |
| Age at dental cast, yr | −0.02 | NS |
| Cleft area, mm2 | 0.93 | <0.001 |
| Palatal area, mm2 | −0.35 | 0.03 |
| Total palatal area, mm2 | 0.20 | NS |
| S–N, mm | −0.30 | NS |
| S–Ba, mm | −0.30 | NS |
| N–S–Ba,° | 0.42 | 0.008 |
| Ba–PMP, mm | −0.05 | NS |
| PMP–ANS, mm | −0.56 | <0.001 |
| PMP–A, mm | −0.55 | <0.001 |
| S–N–ANS,° | −0.33 | 0.04 |
| SNA,° | −0.38 | 0.02 |
| N–ANS, mm | −0.22 | NS |
| R–PMP, mm | −0.31 | 0.05 |
| SN–PP,° | 0.30 | 0.04 |
| Ar–Go, mm | −0.18 | NS |
| Go–Gn, mm | −0.02 | NS |
| Ar–Gn, mm | −0.18 | NS |
| SNB,° | −0.14 | NS |
| S–N–Pog,° | −0.09 | NS |
| SN–MP,° | −0.08 | NS |
| Ar–Go–Gn,° | −0.17 | NS |
| ANS–N–Pog,° | −0.26 | NS |
| ANB,° | −0.30 | NS |
| N–Men, mm | −0.26 | NS |
| S–Go, mm | −0.40 | 0.01 |
| J–J′, mm | −0.03 | NS |
Discussion
The authors demonstrate significant correlation between cleft size and maxillary variables assessed by cephalometry. Large cleft size increases the individual tendency to maxillary retrusion, which affects the anteroposterior jaw relation. Although the correlations between cleft size and maxillary variables are in the moderate range, they are consistent with the hypothesis of an influence of cleft size at the time of palate repair on maxillary growth. Two hypotheses have been proposed to explain the tendency of patients with a large cleft to retrusion: an intrinsic hypothesis implying an inherent tissue deficiency; and an iatrogenic hypothesis suggesting a surgical influence. According to the intrinsic hypothesis, developmental tissue deficiency accounts for the hypoplasia of a maxilla. This view is not supported by the present study because the cleft area was not significantly correlated with the palate area (r=0.06, P=0.7). Previous studies on unrepaired patients with UCLP18, 19, and infants with UCLP prior to primary surgery9 also demonstrated that the tissue deficiency is mild. The cleft size might affect the difficulty of surgical repair, and thus growth outcome (i.e. the iatrogenic hypothesis). A large cleft may require considerable mobilization of palatal mucoperiosteum, resulting in a larger area of palatal denudation and the generation of more scar tissue, with more inhibition of maxillary growth. The deforming effects of surgically denuded palatal bones are supported in animal studies11, 12, 13, 14. In theory, minimal exposure of palatal bones should adversely affect maxillary growth less. The two best centers for facial growth outcome in the Eurocleft multi-centre study performed a single layer vomer flap for closure of the hard palate at the time of lip repair26. The outcome reflecting the minimal interference is possibly due, in part, to the limited exposure of the palatal bone during repair. This finding is in direct contrast to the work of Suzuki et al.27, who reported no relationship between cleft size and later forward growth of the maxilla. The explanation for these discrepant results is unclear. Whether this relates to the number of surgeon involved (single surgeon versus 3 different surgeons), technique used (two-flap versus V–Y push-back), definition of cleft size (area versus width) or other variables is unclear.
Whereas tissue deficiency and tissue displacement may both influence cleft size, the critical factor responsible for the varied cleft size at the time of palate repair remains controversial. As the cleft area and palatal area were measured at the time of palate repair, they may have been affected by lip repair. The effect of lip repair on the position or growth of the posterior maxilla was minimal despite the substantial alveolar bone-bending effect on the anterior maxilla16, 22, 23. The cleft size was more strongly correlated with the cleft area (r=0.93, P<0.001) than with the palatal area (r=−0.35, P=0.03), so we can postulate that the cleft size primarily reflects tissue displacement, mainly through tongue force, rather than tissue deficiency. Previous studies have shown that tissue deficiency in patients with UCLP is mild in the horizontal dimension3, 18, and least occurs in the posterior maxilla3.
Although significant relationships exist between cleft size and the posterior height of the basal maxilla (R–PMP), the cranial base angle (N–S–Ba), and the posterior face height (S–Go) in the present patients, the correlations are mostly in the lower range. Palate repair has no influence on the downward growth of the basal maxilla17 or the shape of the cranial base17, 25. Reduced R–PMP and increased N–S–Ba in patients with unrepaired UCLP have also been found to be related primarily to tissue deficiency and tissue displacement, respectively18. The weak negative correlation of the cleft size with R–PMP (r=−0.31, P=0.05) and the strong positive correlation with N–S–Ba (r=0.42, P=0.008) in the present patients are reasonable findings. The latter finding can also explain the changes in S–Go with cleft size, by vertical displacement of Go, in the present patients.
The finding that patients with UCLP are not the same at the time of palate repair and can be characterized by their cleft size has clinical implications. Treatment outcome in terms of growth could be anticipated according to cleft size. In the case of a child with a cleft size of 13% or less (10% or less when it is converted to a 3-dimensional measurement2), a high chance for good growth outcome might be expected (Fig. 4). This supports the data of Berkowitz et al.1 who demonstrated good palatal growth in patients with cleft size of 10% or less, measured by stereophotogrammetry. The treatment protocol could vary according to the cleft size. In the case of a child with a large cleft, a later closure of the palate or a staged palatal closure might be proposed. This view is supported by previous studies showing that later palate repair results in a longer maxilla because possible interference with maxillary growth is postponed to a later age when less growth remains6, 15, and that a staged palatal closure by starting closure of the soft palate with a posterior vomer flap incorporation may narrow the size of the remaining cleft spontaneously5, 6, 21 or by starting closure of the hard palate with a single layer vomer flap may facilitate a smaller later palate repair26.
Fig. 4.
Comparison of the incidence of good facial growth outcome between patients with cleft size of 13% or less and those with cleft size larger than 13% (good growth outcome indicates the PMP–A being 44
mm or longer; Fan4).
The study has limitations. First, a 2-dimensional technique (i.e. photographic method) was used to examine a 3-dimensional structure (i.e. cleft size), but the photographic method is sufficiently powerful to allow for the recognition of trends in the cleft size. Its relative simplicity, ease of access and low cost, makes it a more practical tool in the investigation of the cleft defect than more-sophisticated techniques (e.g. stereophotogrammetry, laser or computed tomography). Second, the tension of the scar tissue from the lip repair might have some adverse effects on maxillary growth. A number of studies have demonstrated that lip repair has only a mild adverse effect on maxillary growth16, 19, 25. The effect of lip repair on the cleft size at the time of palate repair was minimal, as discussed above. Third, Kharbanda et al.10 have found that patients with poor Goslon scores (i.e. poor dental arch relationships) have significantly smaller anterior arch depth and anterior palate height than those with good Goslon scores (P=0.001 and P<0.05, respectively). Their study showed that the anterior maxillary morphology is a key determinant of the Goslon yardstick as both were measured at the same time (i.e. at about 9 years of age). The stronger relationship with the arch depth than with the palate height is also expected as the anteroposterior relationship is the most crucial aspect in the Goslon classification followed by the vertical relationship. Finally, it is suggested that repetitive palatal surgeries including pharyngeal flaps and fistula closure might contribute to maxillary retrusion20, 24. In this patient group only one had a pharyngeal flap and none had symptomatic fistula requiring surgical management.
In conclusion, in analysing the relationship between cleft size and craniofacial variables in patients with complete UCLP the authors considered whether there was an influence of cleft size at the time of palate repair on maxillary growth. Overall, a negative relationship between cleft size and maxillary length and protrusion was found. Patients with a large cleft at the time of palate repair have a shorter and more retrusive maxilla than those with a small cleft by the age of 9 years.
Funding
The authors declare no sources of funding.
Competing interests
The authors declare no competing interest.
Ethical approval
The principles outlined in the Declaration of Helsinki were followed in the study.
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PII: S0901-5027(10)00291-2
doi:10.1016/j.ijom.2010.01.024
© 2010 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.
Volume 39, Issue 10 , Pages 956-961, October 2010
