Cleft size at the time of palate repair in complete unilateral cleft lip and palate as an indicator of maxillary growth

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.

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 repair . The idea that palate repair is detrimental to maxillary growth originates with the clinical observation of G illes & F ry and the experimental and clinical works of H erfert . H erfert 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 growth . 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 R oss , 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 ( ). 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. Figures 2 and 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, mm 2 187.8 64.7 67–317
Palatal area, mm 2 815.3 102.9 580–999
Total palatal area, mm 2 1003.1 121.4 745–1276
Cleft size a , % 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
a Percentage cleft area/total palatal area.
See Fig. 2 for explanation of abbreviations.

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, mm 2 0.93 <0.001
Palatal area, mm 2 −0.35 0.03
Total palatal area, mm 2 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
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Feb 8, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Cleft size at the time of palate repair in complete unilateral cleft lip and palate as an indicator of maxillary growth
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