Birth prevalence, mutation rate, sex ratio, parents' age, and ethnicity in Apert syndrome.

Apert syndrome was studied to determine birth prevalence, mutation rate, sex ratio, parents' age, and ethnicity among 2,493,331 live births registered in the California Birth Defects Monitoring Program (CBDMP) from 1983 through 1993; 31 affected infants were identified. The sample was completed with an additional 22 cases from the Center for Craniofacial Anomalies (CCA), University of California, San Francisco, for a total of 53 affected children. Birth prevalence, calculated from the CBDMP subsample, was 12.4 cases per million live births (confidence interval [CI] 8.6,17.9). The calculated mutation rate was 6.2 x 10(-6) per gene per generation. Asians had the highest prevalence (22.3 per million live births; CI 7.1,61.3) and Hispanics the lowest (7.6 per million, CI 3.3-16.4). In the large population-based CBDMP subsample, there was an almost equal number of affected males and females, (sex ratio 0.94) but in the clinical CCA subsample, there were more affected females (sex ratio 0.79). For all cases, the mean age of mothers was 28.9+/-6.0 years, and of fathers was 34.1+/-6.2 years. Almost half of fathers were older than 35 years when the child was born; for more than 20% of cases, both parents were older than 35 years. These findings may support the view that point mutations appear to be more commonly associated with paternal than with maternal alleles. Representing the largest systematically ascertained population-based study of Apert syndrome to date, they provide a reliable basis for genetic counseling and decision-making, and for focused research to define the cause of this syndrome.

Auditory and facial nerve dysfunction in patients with hemifacial microsomia.

BACKGROUND: Hemifacial microsomia (HFM) is a common craniofacial disorder characterized by a wide spectrum of anomalies, including conductive hearing loss due to external and middle ear deformities. However, the prevalence of sensorineural hearing loss (SNHL) as well as facial nerve dysfunction is underappreciated. OBJECTIVE: To determine the frequency of auditory and facial nerve dysfunction and its relationship to more severe forms of bilateral HFM. DESIGN: Retrospective medical record review to characterize the clinical severity of HFM and the prevalence and nature of the associated auditory and facial nerve dysfunction. SETTING: Center for Craniofacial Anomalies at the University of California, San Francisco, Medical Center. PATIENTS: Ninety-nine pediatric patients with HFM evaluated at the University of California, San Francisco, Medical Center. MAIN OUTCOME MEASURES: The prevalence of SNHL and facial nerve dysfunction in this patient population and any associations between these 2 characteristics. RESULTS: Hearing loss was present in 74 (75%) of 99 patients, with a conductive component in 73 patients. Sensorineural hearing loss was present in 11 patients ( 11%), with mixed hearing loss in most patients. Fourteen patients required rehabilitation with auditory amplification. Nearly a quarter of the patients (22 [22%] of 99) had facial nerve dysfunction, but only 1 patient had facial palsy on the same side as the SNHL. There was a statistically significant association between having auricular abnormalities and conductive hearing loss or SNHL (P = .30 and .80, respectively). However, there was no statistically significant association between bilateral HFM and the occurrence of either SNHL or facial paralysis, nor was there an association between auditory and facial nerve dysfunction. CONCLUSIONS: Sensorineural hearing loss and facial nerve dysfunction are common in HFM. These findings have important implications in the treatment of patients with HFM.

Electromyographic analysis of the functional components of the lateral pterygoid muscle in the rhesus monkey (Macaca mulatta).

Electromyographic recordings (EMG) obtained from intramuscular electrodes inserted in the lateral pterygoid muscle (lat. pt.) of 29 juvenile and adolescent monkeys were assessed in relation to the recorded activity of three jaw elevating muscles, temporalis, masseter and medial pterygoid, and a jaw muscle depressor, the geniohyoid. The lat. pt. was recruited in one of three patterns: (1) only during mandibular depression, (2) during both depression and elevation, or (3) only during elevation of the jaw. The discharge of fibres in the lat. pt. during closing movements occurred bilaterally in 9 of 21 recordings. Simultaneous recordings from the anterior temporalis, medial pterygoid and the ipsilateral lat. pt. indicated completely different discharge patterns of the three muscles. In 9 recording sessions, two pairs of electrodes were placed in the same lat. pt. The discharge patterns from the two pairs were different in 5 of the recordings. In one region, the fibres were active only during depression, whereas in the other region fibres discharged only during elevation of the mandible. The data support the concept of two groups of fibres with separate functions within the lat. pt. and suggest that adaptation to oral respiration utilizes the two groups in distinctive patterns.

Retrognathism.

Retrognathia is a common deformity that generally requires both orthodontics and surgery for correction. The surgical correction of the problem is best completed in the majority of cases with the sagittal splitting osteotomy. While the surgery is generally successful, relapse is a formidable problem. Instrument registration methods for properly positioning the condyles are being developed, but at this time are not totally successful. Lag screw fixation of the segments is very stable and seems to limit relapse but requires a facial incision with a resulting scar. Future technology probably will allow for internal placement of lag screws. Until such techniques are available, the use of intermaxillary fixation followed by an elastics activated registration bite splint to facilitate healing is recommended.

Maxillary hypoplasia secondary to midfacial trauma in childhood.

Three normal children who suffered midfacial trauma and developed midfacial retrusion that would require Le Fort III advancements for correction of the deformity are described. The common denominator in these three cases seems to be an injury to the medial facial structure including the nasal septum. It is concluded that midfacial fractures in childhood may be a cause of subsequent midfacial hypoplasia.

Aesthetic improvement resulting from craniofacial surgery in craniosynostosis syndromes.

A consecutive series of 21 patients with craniosynostosis syndromes (9 Crouzon's, 6 Pfeiffer's, 6 Apert's) was evaluated for reconstructive postoperative aesthetic improvement resulting from craniofacial surgery (Le Fort III, sliding genioplasty, nasal septal reconstruction and cranioplasty). The same consecutive series of patients had been previously evaluated for stability of Le Fort III advancement. All the patients were assessed at least one year post operatively. Stability of the advancement was confirmed. In the present study, various midline bony and soft tissue profile measurements were obtained from lateral cephalograms. These measurements were compared to similar measurements (standards) in normals. "Normal" standards and "normal" appearance imply harmonious and aesthetically pleasing facial features. This study showed markedly abnormal positions of the selected bony and soft tissue landmarks preoperatively compared to the normal but following surgery the measurements studied approached or were similar to the normal standards. Based on these measurements, the patient's appearance improved significantly following reconstructive craniofacial surgery. Suggestions for additional surgery based on these studies are made.

Changes in zygomatic arch position following experimental lateral displacement.

In order to obtain information about the stability of augmentation procedures in the area of the zygomatic arch, the zygomatic arch on one side was displaced laterally in eight rhesus monkeys by an osteotomy of the anterior portion of the arch and placement of an 8 mm bone graft obtained from the supraorbital ridge. The other side served as a control. The post-operative changes were studied on submento-vertex head films during a 24 month follow-up period. Three months post-operatively the amount of lateral displacement was reduced by 55%. During the next 9 months of follow-up only small changes occurred in the individual animals, and the mean values remained predominantly unchanged. Between 12 and 24 months the distance from the zygomatic arch to the midline increased with growth. On the control side this distance increased from three months on. At 24 months only 18% of the difference in width that was created by the surgical repositioning remained.

Placement of endosseous implants in children and adolescents with hereditary ectodermal dysplasia.

OBJECTIVE: The purposes of this investigation were to study the feasibility of placing endosseous implants in children and adolescents with ectodermal dysplasia and to assess the position and stability of such implants during growth. This article reports on 6 subjects with long-term follow-up. Study design. A prospective study was commenced in 1991. Patients with hereditary ectodermal dysplasia who were over the age of 5 years and who presented to the University of California San Francisco Ectodermal Dysplasia Clinic for dental treatment were included and maintained in the study. In each case, clinical and radiographic records were obtained before treatment, immediately after implant placement, at delivery of the prosthesis, and subsequently at yearly intervals. Six subjects are reported, 4 as members of the prospective study group and 2 who had been treated before the study began. RESULTS: A total of 41 implants (19 maxillary, 22 mandibular) were placed. The average follow-up after implant placement was 7.8 years (range, 6-11 years), and the average time since restoration was 6 years (range, 5-10 years). Forty implants successfully integrated and have been restored. There was no evidence that implant placement or prosthetic rehabilitation resulted in restriction of transverse or sagittal growth. One mandibular implant, placed in a partially dentate 5-year-old, became submerged because of adjacent alveolar development and required placement of a longer abutment. Four maxillary implants placed in a partially dentate 7-year-old also became submerged and required prosthetic revision and the placement of longer abutments. CONCLUSIONS: This preliminary report suggests that endosseous implants can be successfully placed and can provide support for prosthetic restoration in patients with hereditary ectodermal dysplasia. However, vertical dentoalveolar growth results in submergence of the implant relative to the adjacent natural dentition when implants are placed adjacent to erupting permanent teeth.

Some aspects of bone formation and remodeling pertinent to craniofacial development and reconstructive treatment.

Bone formation, modeling, and remodeling occur as physiologic developmental growth or healing processes. Bone formation and turnover is an ongoing process from early organogenesis to the end of life. The assumption can be made that all elements for osteogenesis and resorption are present at any time and can be activated given an appropriate environment. Bone is a dynamic tissue that is readily influenced by its environment. Recognition of this fact is essential in the treatment of dental malocclusions and in reconstruction of jaw, facial, and skull deformities. Examples of experimental studies on various environments for bone formation and clinical application of the experimental findings are here related to treatment of alveolar clefts, bony contour deficiencies, midface hypoplasia, skull bone defects, and traumatically or congenitally underdeveloped, rudimentary, or missing mandibular condyle/ramus units.

Growth characteristics of the premaxilla and orthodontic treatment principles in bilateral cleft lip and palate.

Sixty-three individuals with complete bilateral cleft lip and palate (BCLP) were studied. In 51 of these subjects no surgical set-back or early bone grafting procedures were done. In the other 12 subjects early surgical procedures to reduce the prominence of the premaxilla had been done. In the larger group the premaxilla was, on the average, protrusive until age 12, after which it gradually became more retrusive. By the end of the growth period the premaxilla was not excessively protrusive in any of these subjects. It was concluded that it is advantageous for the premaxilla in individuals with BCLP to be protrusive during most of the growth period, since the premaxilla grows forward at a slower rate than the mandible. In the 12 subjects with premaxillary surgery, midface retrusion was demonstrated at an early age. The forward growth of the premaxilla in these individuals was slower than in the BCLP without premaxillary surgery and all 12 subjects developed rather severe midface retrusion. Orthodontic treatment principles for four different stages of craniofacial and dental development have been outlined.

Morphologic evidence of muscle influence on dental arch width.

Tests on hypotheses to explain changes in arch width during correction of distoclusion with the activator appliance used in this study showed that statistically significant increases occurred in both maxillary and mandibular arch widths during treatment. The increase was substantially larger in the maxilla than in the mandible. The arch width showed no statistically significant decrease after completion of treatment. The activator designed for this study affected orofacial muscle balance. The findings suggest that there were changes in the influence of tongue and cheek muscles on the maxilla. Available experimental as well as clinical data support the assumption that the tongue had taken a higher and more anterior position in the palatal area and that the tension of the cheek muscles was reduced relative to the posterior part of the maxillary dental arch.

Orthodontic management of unilateral cleft lip and palate.

Experimental and clinical findings indicate that unfavorable adaptations of normal structures occur in children with clefts. It is postulated that these deviations from normal development are reversible and can be corrected or prevented by properly designed treatment. On this basis, five hypotheses were formulated and tested on the data from the subjects included in this study. The subjects consisted of 1) 16 children without clefts, 2) eight children who had complete unilateral clefts of the lip and palate but who had not received orthodontic treatment, and 3) 16 children who had complete unilateral clefts of the lip and palate and who had been treated by the described orthodontic procedures. The mean age for each group was 16 years. It was concluded that orthodontic treatment can be designed to : 1) counteract the forces which inhibit development of the maxillary alveolar process horizontally and vertically, 2) partially prevent the reduction in the forward growth of the maxilla, 3) provide adequate jaw and dental arch relationships, and 4) establish and maintain correct position of the maxillary segments.

Mandibular malformations: growth characteristics and management in hemifacial microsomia and Nager syndrome.

This review article describes normal and abnormal development of the mandible. The focus is on the characteristics of the mandible and its attached muscles in the various types of hemifacial microsomia and in Nager syndrome. Management protocols for these two types of malformations are presented in relation to development stages.

Tooth size and morphology in hemifacial microsomia.

AIMS: To determine whether tooth size and morphology are affected in HFM. DESIGN: The mesiodistal diameter of each tooth of 40 patients with varying severity of HFM was measured with a vernier gauge calibrated to 0.1 mm. Data obtained from teeth on the affected side were compared with data from corresponding teeth on the contralateral side. SETTING: Center for Craniofacial Anomalies, School of Dentistry, University of California, San Francisco, USA. RESULTS: Subjects with HFM have smaller teeth on the affected side than on the contralateral side. The more severely affected subjects have the highest degree of tooth size asymmetry. Tooth morphology is also affected in individuals with HFM.

Nasal growth in complete bilateral cleft lip and palate.

Forty-four lateral cephalograms from a sample of 15 white males with bilateral cleft lip and palate (BCLP) were evaluated to determine the growth pattern of the nose, identify timing of the nasal growth spurt, assess growth of the underlying bony elements relative to the nasal growth, and ascertain the relationship of the nose to the rest of the facial profile. The cephalograms (taken at ages 7.5 to 16.6 years) were divided into five groups according to age of subject. Fifteen variables related to soft tissue nose, nasal bone, maxilla, and facial convexity were assessed. Results of this investigation were as follows. First, the nose of subjects with BCLP grew more downward than forward. Second, the growth spurt occurred between the ages of 12 and 16 years. Third, forward growth of the nose was almost always found, whereas the maxilla becomes more retrusive. Fourth, the angle of soft tissue nasion (N')-pronasale (Prn)-soft tissue pogonion (Pog') had an average decrease of 3.56 degrees from age 8 to 16 years. Individual data showed that 12 of 15 patients had a decrease of this angle, whereas 3 had a small increase; 10 of 12 with a decrease demonstrated an increase of both sella-nasion (SN')-Prn and SN'-Pog'. The remaining 2 showed an increase of SN'-Prn and a decrease of SN'-Pog'. Thus, the profile of the nose (N'-Prn-Pog') became more convex over the observed period, which at least in part seemed to be due to the horizontal development of the nose itself.