Finite element morphometry of the midfacial complex in subjects with Angle's Class III malocclusions

The purpose of this study was to determine whether the morphology of the midface differed in normal (Class I) and midfacially-retrognathic (Class III) prepubertal subjects, and to localize differences morphometrically. Lateral cephalographs of 133 European-American children between 5-11 years of age were traced and average geometries, scaled to an equivalent size, were generated based upon seven nodes (pterygoid point, PTS; rhinion, RO; posterior nasal spine, PNS; midpalatal point, MPP; anterior nasal spine, ANS; subspinale, A; and prosthion, Pr). The samples also were subdivided into seven age- and sex-matched groups for morphometric comparisons. Procrustes analysis indicated that the overall midfacial configurations differed statistically (P < 0.05). Therefore, a color-coded finite element (FEM) program was used to localize differences in morphology graphically. Comparing Class I and III groups for size-change, FEM revealed that negative allometry was evident in the posterior half of the midfacial configuration localized between PTS, PNS, and MPP. The anterior half was more isotropic, however, but the anterior-most aspect of the configuration between Pr and RO showed some positive allometry particularly in the premaxillary and incisor regions. For shape-change, major differences in shape over the entire midface were not as evident, with an isotropic midfacial morphology for normal and Class III subjects. It is concluded that an identifiable pattern of deformation is evident for the Class III subjects during the prepubertal growth period. Therefore, midfacial retrognathia associated with Class III malocclusions results, at least in part, from deficient anteroposterior elongation of the midfacial complex allied with deformation of the premaxillary region.     

The effect of unilateral partial facial paralysis and muscle ablation on craniofacial growth and development: an experimental study in the rabbit

The effect of unilateral partial facial nerve ablation and unilateral partial midface muscle ablation on craniofacial growth and development was investigated. New Zealand White rabbits (12 days old) were randomly assigned to three experimental groups: control group, to study normal craniofacial growth and development (n = 15); nerve ablation group, surgically induced unilateral paralysis of the buccal branches of the facial nerve (n = 15); and muscle ablation group, surgical unilateral ablation of the facial muscles innervated by the buccal branches of the facial nerve (n = 12). All animals were operated on at the age of 12 days; follow-up evaluations were performed at the ages of 2 months and 6 months. The age of 2 months represents the endpoint of the prepubertal craniofacial growth and development. At the age of 6 months, the animals are fully grown; therefore, the time period between 2 and 6 months is regarded as the pubertal growth period. Computerized dorsoventral roentgencephalometric (measurement of distances and angles) and computer tomographic (three-dimensional volumetric measurements) investigations were performed at both ages. Additional dry skull measurements were performed to determine more precisely the bone segments involved in the craniofacial growth alterations studied. The obtained results indicated the following. Unilateral partial facial paralysis involving the midface resulted in growth alterations analogous to those seen after unilateral total facial paralysis. The growth alterations were not to be seen as a growth restriction (reduction in bony volume) but as growth misdirections (alterations in shape). Major growth alterations were present in those regions closely related to the facial musculature, namely the nasal, maxillary, and premaxillary regions, resulting in a snout deviation toward the operated side. The growth alterations occurred during prepuberty and remained rather stable during puberty. Morphologic signs of muscle denervation were related to the craniofacial growth disturbances. The growth alterations after unilateral partial facial paralysis were mainly biomechanically induced, as they were analogous to those observed after unilateral midfacial muscle ablation. The fact that after unilateral midfacial muscle ablation at the age of 6 months the severity of the alterations had increased was attributed to the scar formation inherent to the surgical procedure.     

A Monte Carlo study of the inferential properties of three methods of shape comparison

Three inferential morphometric methods, Euclidean distance matrix analysis (EDMA), Bookstein's edge-matching method (EMM), and the Procrustes method, were applied to facial landmark data. A Monte Carlo simulation was conducted with three sample sizes, ranging from n = 10 to 50, to assess type I error rates and the power of the tests to detect group differences for two- and three-dimensional representations of forms. Type I error rates for EMM were at or below nominal levels in both two and three dimensions. Procrustes in 2D and EDMA in 2D and 3D produced inflated type I error rates in all conditions, but approached acceptable levels with moderate cell sizes. Procrustes maintained error rates below the nominal levels in 2D. The power of EMM was high compared with the other methods in both 2D and 3D, but, conflicting EMM decisions were provided depending on which pair (2D) or triad (3D) of landmarks were selected as reference points. EDMA and Procrustes were more powerful in 2D data than for 3D data. Interpretation of these results must take into account that the data used in this simulation were selected because they represent real data that might have been collected during a study or experiment. These data had characteristics which violated assumptions central to the methods here with unequal variances about landmarks, correlated errors, and correlated landmark locations; therefore these results may not generalize to all conditions, such as cases with no violations of assumptions. This simulation demonstrates, however, limitations of each procedure that should be considered when making inferences about shape comparisons.     

Thin-plate spline analysis of the cranial base in subjects with Class III malocclusion

The role of the cranial base in the emergence of Class III malocclusion is not fully understood. This study determines deformations that contribute to a Class III cranial base morphology, employing thin-plate spline analysis on lateral cephalographs. A total of 73 children of European-American descent aged between 5 and 11 years of age with Class III malocclusion were compared with an equivalent group of subjects with a normal, untreated, Class I molar occlusion. The cephalographs were traced, checked and subdivided into seven age- and sex-matched groups. Thirteen points on the cranial base were identified and digitized. The datasets were scaled to an equivalent size, and statistical analysis indicated significant differences between average Class I and Class III cranial base morphologies for each group. Thin-plate spline analysis indicated that both affine (uniform) and non-affine transformations contribute toward the total spline for each average cranial base morphology at each age group analysed. For non-affine transformations, Partial warps 10, 8 and 7 had high magnitudes, indicating large-scale deformations affecting Bolton point, basion, pterygo-maxillare, Ricketts' point and articulare. In contrast, high eigenvalues associated with Partial warps 1-3, indicating localized shape changes, were found at tuberculum sellae, sella, and the frontonasomaxillary suture. It is concluded that large spatial-scale deformations affect the occipital complex of the cranial base and sphenoidal region, in combination with localized distortions at the frontonasal suture. These deformations may contribute to reduced orthocephalization or deficient flattening of the cranial base antero-posteriorly that, in turn, leads to the formation of a Class III malocclusion.     

Diagnosis and treatment planning of hypodivergent skeletal pattern with clockwise occlusal plane rotation

Diagnostic treatment planning of Class III malocclusion is complicated due to the interaction of development, timing, dental pattern, and skeletal relationships. Historically, the treatment of adult Class III malocclusions has tended to be seen primarily as cases of mandibular prognathism. As diagnostic acumen and surgical skills improve and merge, orthodontic and surgical treatment plans for Class III malocclusions have become more common. Class III malocclusions now tend to be described in terms of mandibular prognathism, horizontal maxillary hypoplasia, maxillary vertical hypoplasia, and mandibular dentoalveolar retrusion. The purpose of this paper is to present a combined surgical-orthodontic treatment approach involving clockwise rotation of the occlusal plane for treatment of hypodivergent Class III skeletal pattern and dental malocclusion.     

The arc index in evaluation of Class III malocclusion

Lateral cephalometric radiographs were obtained for 46 individuals (18 men and 28 women) aged 20 to 30 years. The sample consisted of Taiwanese with Class III malocclusions and prognathic facial profiles. A modification of the Sassouni arch analysis was used to evaluate this group. All parameters were compared with the norms for adult Taiwanese. The facial pattern of the Class III group was similar to that reported in other studies. The maxilla was in a retrusive position; the lengths of the maxilla and the mandible were significantly different from those in the normal group; the mandibular central incisor was retroinclined; and the total gonial angle, upper gonial angle, and lower gonial angle in the Class III group were significantly different from those angles in the normal group in both sexes. The arc index represented the maxillomandibular positional relationship. There was a statistically significant difference between the mean arc indexes of the Class III and the normal groups. The results indicated that the more negative the arc index, the greater the Class III tendency.     

Ossification of the distal phalanx of the first digit as a maturity indicator for initiation of orthodontic treatment of Class III malocclusion in Japanese women

The influence of mandibular growth on the stability of orthodontic treatment has been well established. A particular problem is late mandibular growth in patients with Class III malocclusions, because of skeletal jaw discrepancies that may influence the timing and course of treatment, as well as the stability of posttreatment. We have used the ossification of the distal phalanx of the first digit as an indicator of the skeletal maturity of the patient and of their potential for further growth. Our previous studies have shown that fusion of the epiphysis and the diaphysis of the distal phalanx of the first digit occurs from 1 to 3 years after the pubertal growth maximum in Japanese women. In these case reports, the orthodontic treatment of two female patients with mild Class III skeletal malocclusions is presented to show the possible clinical application of the ossification of the first digit as an indicator of the completion or near cessation of mandibular growth in the timing of treatment of Class III malocclusions. The case reports show that, although both patients experienced some mild degree of mandibular growth after treatment, this method can be helpful in determining residual mandibular growth potential in Japanese female patients with Class III malocclusions and mild skeletal discrepancies.     

The status of the developing occlusion of 8-9 year-old children from a lower socio-economic group in a developing country

The aim of this study was to determine the percentage of developing malocclusions that are present at the age of 8-9 years. This data will be used for a follow-up study on the same sample two years hence, in order to formulate soundly based recommendations to Public Health Authorities on the implementation of a community directed, preventive and interceptive orthodontic programme. A total of 936 children were examined by 3 investigators, at 9 primary schools in the lower socio-economic suburbs of a large urban area. The majority of subjects (66.5 per cent) presented with Class I malocclusions. A significantly higher percentage of white children however, presented with Class II malocclusions, while black children showed a higher tendency toward Class III malocclusion. Well circumscribed anterior openbites were found in 27.8 per cent of black children, but no specific causative factors could be identified. Early loss of primary molars and canines occurred in both groups. There was a statistically significant difference (p < 0.05) between the mean posterior arch lengths of the two groups, the black children having on average 2.2 mm longer arch lengths.     

Twenty-year experience with early surgery for craniosynostosis: II. The craniofacial synostosis syndromes and pansynostosis--results and unsolved problems

As the second of a two-part series, 76 patients with pansynostosis and craniofacial synostosis syndromes were retrospectively analyzed. Diagnoses included pansynostosis (7), craniofrontonasal dysplasia (8), and Apert (24), Crouzon (15), and Pfeiffer (15) syndromes. All patients underwent primary fronto-orbital advancement-calvarial vault remodeling procedures at less than 18 months of age (mean 6.1 months). Twenty-eight patients (36.8 percent) required a secondary cranial vault operation (mean age 28.4 months). Additionally, a major tertiary procedure was necessary in 5 patients to deal with persistent unacceptable craniofacial form. To address the associated finding of midface hypoplasia, 64.8 percent (n = 35) of patients underwent Le Fort III midface advancement or had that procedure recommended for them. The remainder were awaiting appropriate age for this reconstruction. The more extensive pathologic involvement of the pansynostosis and craniofacial syndrome group is illustrated. As compared with the isolated craniofacial synostosis group previously reported, the incidence of major secondary procedures (36.8 versus 13.5 percent), perioperative complications (11.3 versus 5.0 percent), follow-up complications (44.7 versus 7.7 percent), hydrocephalus (42.1 versus 3.9 percent), shunt placement (22.4 versus 1.0 percent), and seizures (11.8 versus 2.9 percent) was significantly increased. Complex problems including those of increased intracranial pressure, airway obstruction, and recurrent turricephaly or cranial vault maldevelopment are repeatedly encountered. In addition, that early fronto-orbital advancement-cranial vault remodeling failed to promote midface development and hypoplasia of this region is almost a consistent finding in the craniofacial syndromic group. The average length of postoperative follow-up was 6 years. According to the classification of Whitaker et al., which assesses surgical results, 73.7 percent of patients were considered to have at least satisfactory craniofacial form (category I-II) at latest evaluation. An algorithmic approach to the treatment of all patients with craniosynostosis is presented utilizing early surgical intervention as the key element.     

A modified, lingually supported cantilevered Herbst appliance

This new, fixed-functional appliance/Herbst/Bioprogressive system is designed for patient comfort and mandatory compliance. It also combines the positive clinical effects of four fixed-functional systems. It allows rapid palatal expansion of the upper arch, alveolar uprighting of the lower arch, upper and lower incisor alignment, and sagittal correction of Class II malocclusions to occur simultaneously with one appliance fixed in both arches. It is indicated for use in growing patients with skeletal Class II malocclusions. The ideal timing for treatment is the late mixed dentition. Being able to remove the appliance after one year with the upper second bicuspids erupting slightly Class III so the clinician can immediately begin fixed finishing mechanics would be ideal. This new Herbst design will reduce the frequency of orthognathic surgery and upper bicuspid extraction to camouflage Class II malocclusions. At the same time, it gives total control to the clinician in treating some more difficult, non-compliant patients. Fixed-functional appliances, which improve treatment efficiency and treatment results and provide for patient comfort, while at the same time give the treating clinician almost total control of the three planes of facial growth will open new doors for orthodontic treatment and research in the next century.     

Distraction osteogenesis and its application to the midface and bony orbit in craniosynostosis syndromes

The purpose of this study was to demonstrate the potential advantages of applying distraction osteogenesis techniques to the correction of orbital and midfacial hypoplasia in craniosynostosis syndromes. Fifteen children with various craniosynostosis syndromes underwent Le Fort III advancement assisted by gradual distraction utilizing a pair of internal distraction devices custom-fabricated for each child. The surgical procedure consisted of a Le Fort III osteotomy, implantation of internal devices with initiation of distraction intraoperatively, and an accelerated rate of midfacial advancement over the next 3 to 5 days. Activation of the distraction hardware was accomplished by a percutaneous pin, which was removed at the end of the distraction protocol, allowing the internal devices to fixate the fragment for a minimum of 6 months during the period of consolidation. With follow-up ranging between 3 to 38 months, the average orbital and midfacial advancement was 19.7 mm (range, 12.0-30.0 mm). Proptosis was lessened and facial proportions significantly improved in all patients. Serious complications were not encountered. The modified distraction protocol utilized in this group of patients was aimed at addressing the unique requirements of pediatric craniofacial surgery, and resulted in almost twice the amount of correction previously reported for traditional rigid fixation techniques.     

The ontogeny of morphological differences in the mandible in two inbred strains of mice

We have analyzed the postnatal ontogeny of the mandible of two inbred strains of mice (C3HeB and C57/BL) with conventional statistical analysis of area traits and with Euclidian Distance Matrix Analysis (EDMA). The relative contribution of the distal tooth-bearing part of the mandible to the area of the whole mandible decreases over time. The most prominent differences in shape between mice of 10 days and 25 days postnatal age are found in the lower posterior part of the mandible. Between angular and condylar process intramembranous ossification proceeds at a high rate and gradually fills the space between these two processes. The position of the proximal end of the molar tooth-row is relocated ventrally during this period. Morphological differences between C3H and C57 are most pronounced at 15 days postnatal age. Regions that discriminate best between the two strains change during development. While differences in the coronoid process separate the two groups clearly at 10 and 25 days postnatal age, no significant differences in the coronoid process are found at 20 days postnatal age. Similarly, masseter area shows significant differences at 15 and 25 days postnatal age, while C57 and C3H mice are equivalent for this trait at the other times. The same qualitative results are obtained by Euclidian Distance Matrix Analysis (EDMA): regions of major differences between strains are not consistent among ages. These results suggest that the ontogeny of morphological differences between closely related taxa is quite an erratic process; development of morphometric differences does not proceed smoothly and continuously. This unpredictable pattern of development of morphometric differences is expected if development of the mandible is tightly integrated by epigenetic and regulatory processes.     

Dextromethorphan and dextrorphan in rats: common antitussives--different behavioural profiles

Patients with complete unilateral cleft lip and palate present difficult growth problems. Their anteroposterior discrepancies in jaw and dentition are frequently so severe that some epidemiologic studies report the necessity of orthognathic surgery in 25% of their sample. The aims of this study were three-fold: (1) to delineate diagnostic measures in borderline surgical cases of unilateral cleft lip and palate, (2) to verify the significance of negative overjet as a measure of anteroposterior discrepancy, and (3) to compare these diagnostic measures with those of borderline surgical cases of noncleft Class III malocclusions. The sample consisted of 29 patients with unilateral cleft lip and palate and 25 noncleft Class III Korean patients (mean age, 18.69 years); all had crossbites of all four incisors. Each of their pretreatment study casts and cephalograms were analyzed. The group with unilateral cleft lip and palate was divided into two subgroups on the basis of the method of their anterior crossbite resolution; 18 subjects were treated with orthodontics alone (Cleft-NS) and 11 subjects with orthognathic surgery (Cleft-Surg). The noncleft Class III group was divided into two subgroups; 6 of the subjects were orthodontically treated (Cl III-NS), and 19 were surgically treated (Cl III-Surg). The group with unilateral cleft lip and palate showed smaller SNA and SNB angles than the noncleft Class III group, but the ANB angles and the amount of anterior crossbites showed no statistical differences. When the Cleft-NS and the Cleft-Surg groups were compared, the ANB angle and the Wits measurements were significantly different. When the Cl III-NS and Cl III-Surg groups were compared, the SNB, ANB, L1GoGn, Wits, and the crossbite showed significant differences. For borderline surgical Class III unilateral cleft lip and palate cases, ANB angle, Wits appraisal, and ABGoGn angle were critical diagnostic parameters. On the other hand, the magnitude of anterior crossbite, the negative overjet, was shown not to be a significant measure of anteroposterior discrepancy.     

The importance of the correct restoration of the transverse dimension in midfacial fractures]

The final goal, in reconstructing the facial skeleton of trauma patients, is to obtain good aesthetic and functional outcomes. The surgical technique shown, consists in the reduction and contention of the midfacial fractures. It is based on right placing of the zygomatic arch. In fact, the key to repair midfacial fractures, is the correct placing of the zygomatic arch in relation to the cranial base and the midface. In this way the transversal, vertical and sagittal diameters are regained in their correct space relationships.     

Distribution and immunohistochemical characteristics of neurons in the porcine caudal mesenteric ganglion projecting to the vas deferens and seminal vesicle

The subperiosteal browlift and midface lift combination is a total mobilization of the composite full-thickness soft tissues from the bony skeleton with superior suspension. The object is to correct midfacial ptosis and the "tired" look of the lateral eyelids. It is done in conjunction with a browlift so that a composite correction of the upper and midface is achieved. When indicated, a modified lower cheeklift and the usual procedures for correcting neck deformities are utilized in combination. We believe the procedure is safe and the results reported are natural and long-lasting. This review of 130 cases also stresses technical aspects and the safety of the procedure.     

Monobloc craniomaxillofacial distraction osteogenesis in a newborn with severe craniofacial synostosis: a preliminary report

Severe craniofacial synostosis can be a devastating problem for a newborn infant. Reasons for early surgical intervention include cranial stenosis, hydrocephalus, inadequate globe and corneal protection, compromised airway patency, and feeding problems. In this preliminary report, we describe the management of severe craniofacial synostosis in a newborn infant by means of cranial and midfacial distraction osteogenesis.     

Frontofacial osteotomies, advancement, and remodeling by distraction: an extended application of the technique

The purpose of this clinical report is to present the distraction technique for advancement of the frontofacial skeleton as a unit. Our 14-year-old patient was diagnosed with Carpenter's syndrome and kleblattsch?del deformity at birth. At other centers the patient underwent corrective surgeries, including repeated fronto-orbital advancement in an attempt to correct the residual deformity. This has resulted in bony malunion and recurrent deformity, and it has left the patient with no available donor sites for harvesting of bone graft. The patient had class III malocclusion, severe midfacial and frontal deficiency, and relative turricephaly. We performed frontofacial osteotomies and placement of the distraction devices. Distraction of 20 mm was accomplished, correcting the exophthalmos and midface retrusion and producing class I dental occlusion. We conclude that distraction is an optional surgical method that can be applied in selected cases for advancement of the entire frontofacial skeleton.     

Midfacial growth after costochondral graft construction of the mandibular ramus in hemifacial microsomia

PURPOSE: The purpose of this study was to document vertical midfacial growth after costochondral graft mandibular ramus construction in children with type IIB and type III hemifacial microsomia (HFM). METHODS: This is a retrospective study of 33 children who underwent costochondral graft (CCG) construction for mandibular type IIB (abnormal, small, and medially displaced ramus, n = 19) and mandibular type III (absent ramus and glenoid fossa, n = 14) HFM, between 1980 and 1990. Types I and IIA patients were not included because their milder mandibular deformities were lengthened by osteotomy. Mean age at operation was 6.2 (2 to 10) years, and the mean follow-up period was 5.5 (1 to 13.5) years. Occlusal cant, piriform angle, and intergonial angle were measured on the most current posteroanterior (PA) cephalogram. The ratio of unaffected to affected ramus length was determined on the most current panoramic radiograph. Patient outcomes were classified based on the occlusal cant at the latest follow-up: group 1, successful result with a symmetrical maxilla (occlusal cant of <5 degrees); group 2, acceptable result (occlusal cant > or =5 degrees but <8 degrees), and Group 3, failure (occlusal cant > or = 8 degrees). OMENS scores were calculated for each patient: each of the five major anatomic deformities of HFM (orbital, mandibular, auricular, neural, and soft tissue) were graded 0 to 3 and summed. The mean differences in age at operation and OMENS scores between groups were calculated (ANOVA). RESULTS: At the end of follow-up, patients defined as having a successful result (group 1) had a mean occlusal cant of 2 degrees, a mandibular length ratio of 1.0, and an intergonial angle of 2 degrees. However, the final piriform angle was 7 degrees, indicating less vertical midfacial growth than maxillary alveolar growth. These patients were older at the time of operation (mean age, 6.7 years), and their mean OMENS score (6.3) was significantly lower (P = .004) than in patients in group 2 (mean age at operation, 6.3 years; mean OMENS score, 6.8) and group 3 (mean age at operation, 5.8 years; mean OMENS score, 7.8). In group 2, the occlusal cant, mandibular length ratio, and intergonial and piriform angles did not improve. In group 3, the occlusal cant and piriform angle became worse during the follow-up period. CONCLUSIONS: The results of this study indicate that after construction of the ramus and condyle in type IIB and III HFM patients, vertical midface growth is secondary to a combination of midfacial and alveolar growth. Patients operated on at an older age were more likely to have a successful long-term result. Finally, the severity of the overall deformity, as reflected in a higher OMENS score, appeared to be an important factor in the response to early correction.