One- or two-stage palate closure in patients with unilateral cleft lip and palate: comparing cephalometric and occlusal outcomes.

OBJECTIVE: To assess facial growth and dentoalveolar development in two groups of patients with complete unilateral cleft lip and palate. Primary surgical treatment differed in the timing of hard palate closure. DESIGN: Forty-three patients with unilateral cleft lip and palate were examined. Twenty-two patients underwent early one-stage closure of the hard and soft palate cleft (mean age 23.0 +/- 4.7 months); in 21 patients, the hard palate closure was delayed to 86.3 +/- 39.2 months of age. Lateral cephalograms and dental casts were consecutively analyzed at four stages between 6 and 18 years of age. RESULTS: Lateral cephalometric analysis revealed no significant intergroup differences in the sagittal and vertical craniofacial dimensions at any time. Dental cast analysis showed constriction of the upper anterior arch width at the ages of 6 and 10 years in patients with one-stage surgical palate closure, but a difference could no longer be verified at the ages of 15 and 18 years. CONCLUSIONS: The transverse distances in the upper jaw developed initially more positively in the group with delayed hard palate closure, but it became apparent later that the transverse deficiency after one-stage palate closure could be compensated for. When considering surgical treatment in general, the advantages of the delayed hard palate closure must be weighed against criteria favoring the early one-stage closure of the hard and soft palate.     

Craniofacial growth in unilateral cleft lip and palate: skeletal growth from eight to eighteen years

Sixteen individuals with complete unilateral cleft lip and palate (UCLP) were evaluated for determination of several craniofacial dimensional means and growth rates. Each had undergone primary lip and palatal closure and alveolar bone grafting. Serial cephalographs from ages 8 to 18 years, taken every 2 years, were utilized for determination of six cephalometric dimensions: anterior cranial base, upper and lower facial heights, posterior nasomaxillary height, maxillary horizontal length, and mandibular length. These were then compared to published cephalometric standards of a nonclefted group. All dimensions, except mandibular length, were smaller in the UCLP group. The horizontal maxillary length was the most diminished in mean length and growth rate; it appears to be most affected in UCLP. The remaining dimensions and growth rates are affected by UCLP, but to a lesser degree. These findings indicated that individuals with unilateral cleft lip and palate are primarily and adversely affected by clefting (and the surgery as described) in the horizontal maxilla, both in dimension and growth rate.     

Craniofacial morphological outcome following treatment with three different surgical protocols for complete unilateral cleft lip and palate: a premilinary study

This study compared craniofacial morphology between three groups of children with complete unilateral cleft lip and palate, treated with different surgical protocols. The study included 66 10-year-old children (42 boys and 20 girls) with a complete unilateral cleft lip and palate (22 patients in each of the three groups). Children aged 7 months underwent one-stage surgery, performed by a single surgeon. During surgery, the soft and hard palate and the lip underwent correction. The difference between the groups depended on the hard palate closure. Group I patients had the mucoperiosteal flap elevated on both sides of the cleft. Group II patients had the mucoperiosteal flap elevated on the non-cleft side, and had only a minimal 2–3 mm mucoperiosteal flap elevated on the cleft side. Group III patients had mucoperiostium elevated from the septum vomer to create a single-layered caudally pedicled flap, and had only a minimal 2–3 mm palatal flap elevated on the cleft side. Craniofacial morphology was defined using lateral cephalometric analysis. Significant craniofacial morphological differences were identified between groups I, II and III. Group III demonstrated the most favourable morphology. This indicates that the technique of hard palate closure has significant influence on craniofacial growth and development.     

Etiological aspects on craniofacial morphology in twins with cleft lip and palate

The craniofacial morphology of 39 Finnish twin pairs concordant or discordant for cleft of the lip (CL), unilateral cleft lip and palate (UCLP), or cleft palate only (CP) was studied by means of lateral cephalometric radiographs. The intrapair differences between various cleft and twin subgroups were compared by means of univariate analysis; multivariable analysis of cleft discordant pairs and the variance components were estimated with the TWINAN program. Larger values for intrapair differences were found, especially in linear measurements in older twin pairs. Heritability estimates for the cranial base measurements and, to a lesser extent, for the mandibular measurements were high. Comparisons on the basis of cleft type revealed more differences between twin pairs when clefting was more severe. Concordant and discordant CP twin pairs showed similarity in their intrapair craniofacial morphology, indicating that surgery seemed to have no major effect on their craniofacial morphology. A similar comparison in discordant UCLP showed that, in addition to clefting itself, external factors, i.e., the repaired cleft's direct effects on craniofacial morphology, have a strong influence on craniofacial morphology, especially in the maxillas of the UCLP twins. The craniofacial morphology in these Finnish twins supports the hypothesis of different genetic behavior for cleft lip and cleft lip and palate (CL(P)) and CP in Finland.     

Long-term evaluation of bilateral cleft lip and palate patients after early secondary closure and premaxilla repositioning

The aim of this retrospective, mixed longitudinal study was to assess the long-term outcome of early secondary closure and premaxilla osteotomy in 40 bilateral cleft lip and palate patients who underwent early secondary osteotomy of the premaxilla and bone grafting at the age of 8-12 years. Clinical and cephalometric evaluations of profile, lip relation, nasolabial angle and position of the maxilla preoperatively, postoperatively and at adolescence were compared to normal values of non-cleft individuals and the reported data of 90 bilateral cleft lip and palate patients treated in Oslo. In 68% of patients the profile was considered acceptable, but in 26 maxillary growth appeared to be impaired by cephalometric standards. In four patients a Le Fort I osteotomy was carried out and nine patients would have benefited from such a procedure. This study reveals a trend towards maxillary growth retardation partially compensated by orthodontic and dental treatment. Since the results are comparable to those reported for the Oslo group with regard to maxillary growth, the surgical protocol followed does not require revision. Considering the benefits, i.e. closure of alveolo-palatal cleft, continuity of dental arch, eruption of canine in the graft and closure of oro-nasal communications, this mode of treatment should be continued.     

不同的早期治疗模式对单侧完全性唇腭裂患者颌面形态的影响

目的 探讨不同的早期治疗模式对非综合征性单侧完全性唇腭裂患者(UCCLPAs)颌面形态的影响.方法 纳入47位6~7岁的非综合征性单侧完全性唇腭裂患者为病例组,将其按不同的早期治疗模式分为4组,纳入13位性别及年龄与之相当的单侧不完全性唇裂患者为对照组.通过比较反映颌面形态的8个指标来评价病例组和对照组颌面部骨性形态差异.统计采用t检验、单因素方差分析及秩和检验方法.结果 与对照组相比,12月龄前修复唇裂的UCCLPAs的骨性咽腔深度(Ba-PMP) 减小(P<0.05).与未修复腭裂的UCCLPAs相比, 12月龄前修复唇裂,24月龄前修复腭裂的UCCLPAs的面突度(SNA)减小(P<0.05),上颌骨后面高(R-PMP)减小(P<0.05).病例组间相比,3月龄前行唇粘连术,12月龄前行硬腭犁骨瓣整复术的 UCCLPAs 的上颌骨位置(S-Ptm)偏后(P<0.05).结论 当UCCLPAs 6~7岁时,3月龄前行唇粘连术,且12月龄前行硬腭犁骨瓣整复术者的患者上颌骨生长受抑制最严重.24月龄内行硬腭裂整复术者上颌骨向前的生长及后面高的生长均会受抑制.     

Associations between severity of clefting and maxillary growth in patients with unilateral cleft lip and palate treated with infant orthopedics.

OBJECTIVE: The purpose of this study was to examine possible associations between severity of clefting in infants and maxillary growth in children with complete unilateral cleft lip and palate. DESIGN: This was a retrospective study of measurements made on infant maxillary study casts and maxillary cephalometric variables obtained at 5 to 6 years of follow-up. SETTING: The study was performed at the Institute of Reconstructive Plastic Surgery of New York University Medical Center, New York, New York. PATIENTS: Twenty-four consecutive nonsyndromic unilateral complete cleft lip and palate patients treated during the years 1987 to 1994. INTERVENTIONS: All the patients received uniform treatment (i.e., presurgical orthopedics followed by gingivoperiosteoplasty to close the alveolar cleft combined with repair of the lip and nose in a single stage at the age of 3 to 4 months). Closure of the palate was performed at the age of 12 to 14 months. RESULTS: Infant maxillary study cast measurements correlated in a statistically significant manner with maxillary cephalometric measurements at age 5 to 6 years. CONCLUSIONS: The results demonstrate the large variation in the severity of unilateral cleft lip and palate deformity at birth. Patients with large clefts and small arch circumference, arch length, or both demonstrated less favorable maxillary growth than those with small clefts and large arch circumference or arch length at birth.     

Results of randomized controlled trial of soft palate first versus hard palate first repair in unilateral complete cleft lip and palate.

OBJECTIVE: To compare the outcomes for primary repair of unilateral cleft lip and palate, operating on the soft palate first versus the hard palate first. DESIGN: Randomized controlled trial. SETTING: The Regional Cleft Service of West Nepal. PATIENTS: Forty-seven consecutive patients with nonsyndromic unilateral cleft lip and palate, of whom 37 were assessed 4 to 6 years after completing primary surgical repair. INTERVENTIONS: Primary repair of unilateral cleft lip and palate by two differing sequences: (1) soft palate repair, with hard palate and lip repair 3 months later; and (2) lip and hard palate repair, followed by the soft palate repair 3 months later. MAIN OUTCOME MEASURES: Analysis of dental study models, weight gain, and speech recordings. RESULTS: Four to 7 years after completing the cleft closure, there was no significant difference in facial growth between the two types of repair sequencing. Completing posterior repair first had no effect on anterior alveolar gap width. It narrowed the hard palate gap by reducing the intercanine distance. Anterior repair dramatically closed the anterior alveolar gap, and narrowed the intercanine distance. Comparing anterior alveolar gap width with age at first presentation demonstrated that there was no spontaneous narrowing of the cleft in older children. Completing posterior closure first had a weight gain advantage over anterior closure first. Improved oropharyngeal closure, and thus swallowing, is the likely explanation. CONCLUSION: Changing the sequencing of cleft closure has no demonstrable difference in facial growth at 4 to 7 years after completion of the primary surgery.     

A two-centre study on facial morphology in patients with complete bilateral cleft lip and palate at nine years of age

The aim of this study was to compare craniofacial morphology and soft tissue profiles in patients with complete bilateral cleft lip and palate at 9 years of age, treated in two European cleft centres with delayed hard palate closure but different treatment protocols. The cephalometric data of 83 consecutively treated patients were compared (Gothenburg, N = 44; Nijmegen, N = 39). In total, 18 hard tissue and 10 soft tissue landmarks were digitized by one operator. To determine the intra-observer reliability 20 cephalograms were digitized twice with a monthly interval. Paired t-test, Pearson correlation coefficients and multiple regression models were applied for statistical analysis. Hard and soft tissue data were superimposed using the Generalized Procrustes Analysis. In Nijmegen, the maxilla was protrusive for hard and soft tissue values (P = 0.001, P = 0.030, respectively) and the maxillary incisors were retroclined (P < 0.001), influencing the nasolabial angle, which was increased in comparison with Gothenburg (P = 0.004). In conclusion, both centres showed a favourable craniofacial form at 9-10 years of age, although there were significant differences in the maxillary prominence, the incisor inclination and soft tissue cephalometric values. Follow-up of these patients until facial growth has ceased, may elucidate components for outcome improvement.     

Rehabilitative treatment of cleft lip and palate: experience of the Hospital for Rehabilitation of Craniofacial Anomalies-USP (HRAC-USP)--part 2: pediatric dentistry and orthodontics

The aim of this article is to present the pediatric dentistry and orthodontic treatment protocol of rehabilitation of cleft lip and palate patients performed at the Hospital for Rehabilitation of Craniofacial Anomalies - University of São Paulo (HRAC-USP). Pediatric dentistry provides oral health information and should be able to follow the child with cleft lip and palate since the first months of life until establishment of the mixed dentition, craniofacial growth and dentition development. Orthodontic intervention starts in the mixed dentition, at 8-9 years of age, for preparing the maxillary arch for secondary bone graft procedure (SBGP). At this stage, rapid maxillary expansion is performed and a fixed palatal retainer is delivered before SBGP. When the permanent dentition is completed, comprehensive orthodontic treatment is initiated aiming tooth alignment and space closure. Maxillary permanent canines are commonly moved mesially in order to substitute absent maxillary lateral incisors. Patients with complete cleft lip and palate and poor midface growth will require orthognatic surgery for reaching adequate anteroposterior interarch relationship and good facial esthetics.     

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

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.     

Long-term evidence for favorable midfacial growth after delayed hard palate repair in UCLP patients.

OBJECTIVE: To investigate whether delayed hard palate repair resulted in better midfacial growth in the long term than previously achieved with "conventional" surgical methods of palatal closure. DESIGN AND SETTING: Long-term cephalometric data from patients with unilateral cleft lip and palate were available from two Scandinavian cleft centers. The patients had been treated by different regimens, particularly regarding the method and timing of palatal surgery. Patients were analyzed retrospectively, and one investigator digitized all radiographs. PATIENTS: Thirty consecutively treated subjects from each center, with cephalograms taken at three comparable stages between 10 and 16 years of age. RESULTS AND CONCLUSIONS: Patients whose hard palates were repaired late (early soft palate closure followed by delayed hard palate repair at the stage of mixed dentition) had significantly better midfacial development than patients in whom the hard palate was operated on early with a vomer flap, and then during the second year of life, the soft palate was repaired with a push-back procedure. As the growth advantage in the delayed hard palate repair group was accomplished without impeding long-term speech development, the delayed repair regimen proved to be a good alternative in surgical treatment of patients with unilateral cleft lip and palate.     

Correlation between surgical protocols for palatoplasty and midfacial growth in cleft lip and palate patients: A long-term,single centre study

To evaluate and compare the outcomes of two different surgical protocols for palatoplasty for midfacial growth in patients with cleft lip and palate.A retrospective observational cohort study was conducted in 80 patients with cleft lip and palate, who were divided into two groups. Group 1 comprised patients who underwent operation between 9 and 11 months of age using the Bardach two-flap technique without a palatal pushback. Group 2 comprised patients who had undergone operation between 18 and 20 months of age using either a Bardach two-flap technique with a palatal pushback or a von Langenbeck technique. Patient follow-up was done between 8 and 9 years of age when they reported to the centre for secondary alveolar bone grafting. Post-surgical cephalometric measurements were taken for midfacial growth analysis.Group 1 underwent palatoplasty at significantly younger ages than Group 2 (p < 0.01). A statistically significant difference(p < 0.01) was found between the two groups of patients on comparison of cephalometric parameters such as SNA, ANB, CoA, NperpA ANS-PNS, N-ANS, N–Me, Witt's (AO-BO). Group 2 had more positive cephalometric values as compared to Group 1, thereby implying that there was less incidence of midfacial hypoplasia in patients treated at the age of 18–20 months. Between the types of palatoplasty techniques within Group 2, i.e., Bardach two-flap and von Langenbeck, there was no statistical difference found in the post-opertative cephalometric values, i.e., SNA, ANB, CoA, ANS-PNS, N-ANS, N–Me, Witt's (AO-BO) except for Nperp-A, which showed a statistical difference (p = 0.03).Within the limitations of the study which is only a single center experience it seems that palatal closure should be carried out at 18–20 months of age for better midfacial growth, leading to decreased incidence of maxillary hypoplasia at a later stage in life. Repair at less than 18 months of age is also associated with mid-facial hypoplasia.     

Transverse maxillary growth in combined cleft lip and palate. A longitudinal roentgencephalometric study by the implant method.

Transverse maxillary growth was studied radiographically by the metallic implant method in 5 Danish boys with combined cleft lip and palate. The study covered the age range of five to 20 years with individual observation periods of 9 to 12 years. Lip closure and palate closure had been performed at two months and 24 months of age respectively by conventional methods. Orthodontic treatment was carried out in all cases. The maxillary width was determined from posteroanterior cephalometric radiographs as the distance between metallic implants inserted at the lower aspect of the maxillary-zygomatic process on both sides. Other roentgencephalometric measurements were obtained for further estimate of the facial growth in width. Distance curves and velocity curves for these measurements and for body weight were constructed and compared. The growth curves for maxillary width differed definitely from normal and indicated that the spontaneous transverse palatal growth was inhibited in these patients.     

Dentocraniofacial morphology of 21 patients with unilateral cleft lip and palate: a cephalometric study.

OBJECTIVE: To assess the skeletal and dental craniofacial proportions of unilateral cleft lip and palate patients who were operated upon using the Malek technique, and compare them with a normal group to highlight the effect of surgical correction on craniofacial development during growth. DESIGN: Retrospective. METHODS: The cleft palate was closed using the Malek technique in a single operation at 3 months for 11 patients (complete closure of lip and palate) and in a two-stage operation for 10 patients (soft palate at 3 months, lip and hard palate at 6 months). Comparisons were made with a normal control group. Angular and linear measurements of anterior and posterior dimensions of the upper and lower compartments of the face were measured in the 7th and 12th years. RESULTS AND CONCLUSION: No significant differences were observed between the two groups of palate technique repair, although significant differences were observed between craniofacial dimensions of normal versus cleft lip and palate patients. At a skeletal level, the maxilla and mandible were retrusive relative to the cranial base in the cleft lip and palate group. In fact, there was a backward rotation of the palatal plane with repercussions on the maxillo-mandibular complex position. Furthermore, the maxilla was shorter than in normal patients, whereas the mandible was normally shaped. The upper incisors were retroclined and they locked the lower incisors in linguoversion. There was a posterior skeletal deficit of the respiratory compartment, compensated by more marked posterior maxillary alveolar growth. Facial growth in cleft lip and palate patients followed the same pattern, but was delayed compared with normal patients.     

A comparison of growth impairment and orthodontic results in adult patients with clefts of palate and unilateral clefts of lip, palate and alveolus

OBJECTIVE: To evaluate and compare the long-term aesthetic and functional results of surgical and orthodontic treatment in patients with cleft palate and unilateral cleft lip, palate, and alveolus. DESIGN: 30 patients with unilateral cleft lip, palate, and alveolus and 30 patients with isolated cleft palate, mean age of 18.9 years, were evaluated by cephalometric and model analysis a mean of 1.5 years after orthodontic treatment. In each group the surgical treatment has been similar. RESULTS: Model analysis: The sum of every mesiodistal tooth diameter in the maxilla and in the mandible was recorded according to the Bolton analysis. Twenty patients with unilateral cleft lip, palate and alveolus had relatively large upper dental arches and nine had relatively large lower dental arches. Twenty-two patients with cleft palates had large upper dental arches and seven had large mandibular arches. Eleven patients with unilateral cleft lip, palate, and alveolus and 18 patients with cleft palate had a negative space supply (the sum of the mesiodistal tooth diameters compared with the sagittal length of the alveolar ridge) in the region of the lateral teeth. All patients had persistent transverse space deficits that were increased on the side of the cleft in patients with cleft lip, palate, and alveolus. These unilateral transversal space deficits were recorded in 22 patients with unilateral cleft lip, palate, and alveolus and in 8 patients with isolated cleft palate. Sagittal measurements were reduced in 26 patients with unilateral cleft lip, palate, and alveolus and in 23 patients with cleft palate alone. The alveolar midline of the maxilla and the mandible were displaced in 25 patients with unilateral cleft lip, palate, and alveolus and in 19 patients with isolated cleft palate. Lateral cephalometric analysis: The lateral cephalograms taken at the same time as the models showed a mean SNA of 76.8 degrees and a NL-NSL angle of 8.7 degrees, indications of a tendency towards maxillary retrognathia in patients with unilateral cleft lip, palate, and alveolus. Patients with cleft palate had a mean SNA of 79.6 degrees and NL-NSL angle of 8.1 degrees. The anterior facial vertical index was within normal limits in patients with cleft lip, palate, and alveolus (44% vs 56%). An anterior facial height index of 42% compared with 58% in patients with isolated cleft palate indicated a slight reduction in midface height with an increase in the lower face as a consequence. CONCLUSION: Orthodontic and surgical treatment can result in satisfactory results on model analysis. However, there is specific growth impairment of the maxilla 1.5 years after termination of orthodontic treatment and this influences the final cephalometric analysis, particularly in patients with cleft lip, palate, and alveolus.     

用颈椎骨龄对单侧完全性唇腭裂患者发育情况的评估

目的：用颈椎骨龄来评估单侧完全性唇腭裂（unilateral complete cleft lip and palate ,UCLP）患者的发育情况。方法将45例9～16岁的UCLP患者作为试验组（UCLP组）;另选取年龄、种族与UCLP组相匹配的45例非唇腭裂（none cleft lip and palate,Non?cleft）患者作为对照组（Non?cleft组）。拍摄头颅定位侧位片。通过头颅定位侧位片分别测量计算UCLP组与Non?cleft组的颈椎骨龄。对相同性别的UCLP组与Non?cleft组分别进行独立样本t检验。结果 UCLP组男性患者的颈椎骨龄比Non?cleft组小且差异有统计学意义（P<0.05）,而UCLP组女性患者的颈椎骨龄与Non?cleft组差异无统计学意义（P>0.05）。结论与Non?cleft患者相比,9～16岁年龄段男性UCLP患者的发育相对迟缓,而女性患者之间无明显差异。     

胎儿唇腭裂手术无瘢痕愈合机制

唇腭裂是口腔颌面部常见的先天性畸形,胎儿唇腭裂手术有无瘢痕愈合、无继发畸形、诱导颅面正常愈合的优点。关于胎儿唇腭裂手术无瘢痕愈合的机制是研究的热点。本文就此进行综述。     

Dental age in children with a complete unilateral cleft lip and palate.

OBJECTIVE: To assess dental age in children with a complete unilateral cleft lip and palate and to compare this with a noncleft control group. DESIGN: Two-group, mixed-longitudinal cohort study. SETTING: Cleft group from an academic center for cleft lip and palate treatment. Noncleft control group from the same population. PATIENTS: Participants included 70 Caucasian children with a full complement of teeth and a complete unilateral cleft lip and palate (45 boys and 25 girls) from the Cleft Palate Craniofacial Center at the Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands. The control group (90 boys and 91 girls) was taken from the Nijmegen Growth Study. MAIN OUTCOME MEASURE: Dental age was assessed on orthopantomograms. In the unilateral cleft lip and palate group, linear interpolation in individual age curves was applied to obtain the dental age at 5, 9.5, and 14 years of age. For these ages, a comparison was made with the noncleft control group. RESULTS: Boys and girls with a unilateral cleft lip and palate showed a significant delay in dental age, as compared with their noncleft peers at all three ages. This delay was more pronounced in boys than in girls. The gender effect was significant at chronological ages 5 and 14 years. CONCLUSIONS: Children with a complete unilateral cleft lip and palate have a delay in dental age, compared with noncleft children.     

Incidence of cleft lip and palate in the northeast of Mexico: a 10-year study

In Latin American countries, studies on the incidence of cleft lip and palate are not widely available. A 10-year retrospective study was carried out to determine the incidence of cleft lip and palate at the Autonomous University of Nuevo Leon's University Hospital. The study included data from patients who attended the plastic surgery outpatient clinic from January 1990 to December 1999. The author reviewed 10,843 files from which 376 patients were selected to identify the following variables: time of the year in which the first consultation took place, gender, birthplace, type of cleft, age of both parents, and medications taken during pregnancy. The highest incidence was found in patients aged 1 to 6 months. Ninety-four patients had a primary palate cleft; 76 had a secondary palate cleft; and 206 had primary and secondary palate clefts. The gender distribution of the 206 patients with primary and secondary clefts was 127 boys and 79 girls. The mean parent age was 29.5 years (father) and 25.7 years (mother). The incidence of cleft lip and palate in the cited hospital was 1.1:1000 births. Clefts of the left side occurred more often than of the right. Boys were affected more commonly than girls.