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Differential craniofacial skeletal changes after postnatal experimental surgery in young and adult animals.

To find answers to the many questions about abnormal postnatal growth and change of the craniofacial skeleton, a series of surgical experiments was carried out in both young and adult animals. The purpose of this review is to relate this information to basic ideas about bone change and some local factors which may or may not affect skeletal changes. No gross regional deformity was noted after resection of sutures in young animals. The growth of bone at sutures was secondary or compensatory to other factors. In young animals, increase in size of the nasal or orbital cavities decelerated considerably after resection of either nasal septum or orbital tissues. With an increase in volume of orbital contents, orbital volume increased. These prominent gross changes in young animals were not noted in adult animals after resection of nasal septum, enucleation of the eye, or intrabulbar injection of silicone. After unilateral resection of the mandibular condyle in both young and adult monkeys, an extreme unilateral facial skeletal deformity developed. The important factor apparently was loss of integrity of the temporomandibular joint rather than loss of a growth site. The craniofacial skeleton, a three-dimensional mosaic of bones and cavities, develops as a result of the synchronous coordination of the differential activities at various sites. The dynamics of the growth and change are a fascinating, complex, incomplete chapter of biology. An understanding of factors that may or may not influence the craniofacial skeleton in both young and adult animals can aid diagnosis and surgical treatment.

Age Factors↗

Basic mechanisms in craniofacial growth.

Bone growth is controlled by growth areas, not active growth centers as stated earlier. Conversion of cartilage, sutural deposition, and periosteal remodeling are the basic phenomena involved in growth mechanisms. The principles of bone growth will result in changes in the size and shape of the mandible and the nasomaxillary complex in the three dimensions. The growth rate varies at different times during the development of the child. The processes of facial growth and changes in the dental arches continue to a much later age than had previously been realized. Although our knowledge of craniofacial growth has increased during recent times, it is still incomplete with regard to the explanation for the regulation of craniofacial growth.

Adolescent↗

Craniofacial and occlusal characteristics in unilateral cleft lip and palate patients from four Scandinavian centres.

Craniofacial morphology and dental occlusion were studied at early school age in 15 consecutive patients with unilateral cleft lip and palate from each of four Scandinavian cleft centres. Treatment differed mainly in the techniques of palatal repair. Push-back closure of the palate particularly impaired maxillary development, which resulted in an increased incidence of crossbite and reduced intercanine distance when compared with patients who had been operated on by the von Langenbeck method or in whom the anterior palate had not yet been closed.

Cephalometry↗

[The establishment of a computerized growth prediction system].

Natural craniofacial growth plays an important role in the etiology of malocclusion. So, craniofacial growth prediction is very necessary in orthodontics. The present author have developed a new-typed computerized craniofacial growth predition system, which was designed in the general sense of craniofacial growth. According to a unique method, the system could automatically predict of craniofacial growth to different craniofacial growth pattern. It can be used as an auxilliary tool in clinical, teaching and researches in orthodontics.

Adolescent↗

Craniofacial correlates of dietary consistency in a nonhuman primate.

Forty-three squirrel monkeys were raised on either naturally tough or artificially softened foods. Significant differences were found in craniofacial and occlusal development between hard and soft diet animals: The latter exhibit maxillary arch narrowing, palatal arching, rotated and displaced teeth, crowded premolars, and retarded cranial bone mineralization. The correlates in results between soft diet squirrel monkeys and American children suggest that dietary consistency may be an important factor in human craniofacial growth.

Animals↗

[The limits of conservative care in pedodontics].

Despite progress in the decrease of caries by means of many preventive dental programs, children's teeth of poor socio-economic groups are still strongly affected. The well known role of children's teeth in oro-facial growth and harmony, as well as in the development of functions as chewing, speaking or phonation and swallowing, has justified their preservation during all their functional periods. Several conservative therapies allow to reach this purpose. However, extensive dental caries, difficulty to get child tooth infection under control, injuries on permanent tooth germs and child's general health deficiency, can limit preservation of infected teeth, leading to their extraction.

Algorithms↗

Cervical and craniocervical posture as predictors of craniofacial growth.

The present study aimed to determine whether growth changes in craniofacial structure could be predicted by variables expressing the postural relations of the head and the cervical column. The sample comprised 34 children, 16 girls and 18 boys. Cephalometric radiographs obtained in natural head position (mirror position) were taken on two occasions before orthodontic treatment. Mean age was 9.9 years at time 1 and 12.7 years at time 2. Selection of the sample was based on skeletal maturity at time 2 indicating peak activity in pubertal growth. Forty-one reference points and four fiducial points were digitized on each film. Individual growth changes in craniofacial structure were determined by computerized structural superimposition of the digitized sets of points. Correlation coefficients were calculated between 11 postural variables at the first observation and the subsequent growth rate in 36 structural variables. Uniform fields of low to moderate correlation coefficients significant at the 5%, 1%, and 0.1% levels (0.3 to 0.6) were found for eight structural variables, indicating that a small craniocervical angle and a backward-inclined upper cervical column at time 1 was associated with horizontal facial development characterized by reduced backward displacement of the temporomandibular joint (TMJ), large maxillary growth in length, increased facial prognathism, and larger than average true forward rotation of the mandible; whereas, a large craniocervical angle and an upright position of the upper cervical column at time 1 was associated with vertical facial development characterized by large backward displacement of the TMJ, reduced growth in length of the maxilla, reduced facial prognathism, and less than average true forward rotation of the mandible. The findings are in agreement with a theoretical model for the developmental interaction between head posture and facial structure.

Cephalometry↗

Development of hemiface size asymmetry.

Facial size asymmetries for the upper and lower face were measured from photographs of 40 neonates (3 days old), 40 preschoolers (2-4 years), and 40 young adults (18-24 years), approximately equally divided by sex. The right hemiface was significantly larger than the left in the three age groups, and there were no differences in the distributions of asymmetry as a function of age.

Adolescent↗

Targeted deletion of a branchial arch-specific enhancer reveals a role of dHAND in craniofacial development.

The basic helix-loop-helix transcription factor dHAND is expressed in the mesenchyme of branchial arches and the developing heart. Mice homozygous for a dHAND (Hand2) null mutation die early in embryogenesis from cardiac abnormalities, precluding analysis of the potential role of dHAND in branchial arch development. Two independent enhancers control expression of dHAND in the heart and branchial arches. Endothelin-1 (ET-1) signaling regulates the branchial arch enhancer and is required for dHAND expression in the branchial arches. To determine the potential role of dHAND in branchial arch development and to assess the role of the ET-1-dependent enhancer in dHAND regulation in vivo, we deleted this enhancer by homologous recombination. Mice lacking the dHAND branchial arch enhancer died perinatally and exhibited a spectrum of craniofacial defects that included cleft palate, mandibular hypoplasia and cartilage malformations. Expression of dHAND was abolished in the ventolateral regions of the first and second branchial arches in these mutant mice, but expression was retained in a ventral domain where the related transcription factor eHAND is expressed. We conclude that dHAND plays an essential role in patterning and development of skeletal elements derived from the first and second branchial arches and that there are heterogeneous populations of cells in the branchial arches that rely on different cis-regulatory elements for activation of dHAND transcription.

Animals↗

Realities of craniofacial growth modification.

Facial growth modification can be an effective method of resolving skeletal discrepancies. There still is much controversy regarding our understanding of the nature and extent of skeletal orthopedic change possible in individual patients and the most effective appliances and timing of such treatment. In the treatment of class II patients, growth modification can lead to an improvement, if not complete correction of the class II malocclusion. Although two-phase treatment with an early first prepubertal phase can be effective, a later single-phase approach during early puberty seems to be equally effective. Certainly, before surgical correction of the mild to moderate skeletal class II problem in a growing patient is considered, an orthopedic phase of treatment prior to the pubertal growth spurt is an appropriate first step. Skeletal class III patients with a maxillary deficiency stand to gain significant benefits from early orthopedic treatment. However, such therapy may produce more favorable changes for older children and adolescents than previously thought. Nevertheless, orthopedic correction of the mild to moderate skeletal class III should be accompanied by regular progress evaluations to avoid creating significant dental compensations in the face with little skeletal change that ultimately requires surgery anyway. Skeletal class III patients with mandibular excess and/or vertical excess are poor candidates for growth modification. Orthopedic palatal expansion appears to be effective and stable at any time prior to late puberty, a stage of development when ossification of the maxillary sutures is more advanced. Consequently, the timing for expansion may be better determined by the specific needs of each patient. A functional shift resulting from a crossbite is optimally corrected early, so that asymmetric growth of the mandible can be reduced or even prevented. Postpubertal orthopedic expansion is likely to result in bone bending, which will reverse itself over time, potentially leaving periodontal compromise of the maxillary posterior teeth. Therefore, surgically assisted expansion should be considered in such cases. Vertical maxillary excess is challenging to treat with growth modification. The combination of interocclusal acrylic bite blocks combined with a high-pull headgear presently appears to be the best means available. Unfortunately, this treatment has limited success, it must be continued over many years owing to the long-term nature of vertical growth, and it is counterproductive in achieving a balanced sagittal jaw relationship in class I or class III patients with vertical excess. Future research will permit us to have a greater understanding of the nature and extent of facial growth modification possible in individual patients and the optimal appliances and timing of treatment to achieve the best outcome. The development of intraoral osseointegrated attachments such as implants and onplants hold promise for a future means of dissipating orthopedic forces to prevent unwanted dentoalveolar changes that presently occur with our tooth-borne appliances. Analogous attachments presently are undergoing clinical testing for surgically assisted orthopedic movements associated with distraction osteogenesis.

Adolescent↗

A morphometric analysis of craniofacial growth in cleft lip and noncleft mice.

Differences in face shape are considered a factor in cleft lip malformation. The purpose of this study was to analyze craniofacial growth in two strains: A/WySn with 28% cleft lip and C57BL/6J without cleft lip. Standardized photographs of 27 A/WySn and 25 C57BL/6J embryos with 34-46 somites (S) were taken in the superior, frontal, and lateral views. Landmarks were located and digitized for computerized analysis of growth change relative to somite number and at stages of face development before, during, and after primary palate closure. The results showed that both strains had similar overall growth patterns with increases in head width and face width, and decreases in nasal pit width. During early palatal closure in C57BL/6J mice, the nasal pit width was unchanged as brain width increased rapidly; and then later, the nasal pit width decreased as brain width increased slowly. However, during early closure in A/WySn mice, the nasal pit width decreased rapidly as brain width increased slowly; and then later, the nasal pit width was unchanged as brain width increased more rapidly. During early palatal closure, the narrower nasal pit width in A/WySn mice appeared to result from delayed growth of the supporting forebrain as the nasal pits become more medially positioned with normal face development. From the lateral view, the maxillary prominence depth was also smaller in the A/WySn strain during early palatal closure. This deficient forward growth of the maxillary prominences and the narrower positioning of the medial nasal prominences in A/WySn embryos appear to reduce the contact between the prominences and thus predispose this strain to cleft lip malformation.

Animals↗

The concept of pattern in craniofacial growth.

1. There are semantic and associated problems with the word pattern in biology, particularly in orthodontics and facial growth. 2. Pattern, as we use the term, is invariance of relationships--"a set of constraints operating to preserve the integration of parts under varying conditions and through time." 3. Craniofacial pattern can be described and quantified by the identification of craniofacial constants, measures that are relatively invariant. 4. Growth is change and is best identified by studying those measures of size and shape that vary most sensitively through time over development stages. 5. The many traditional cephalometric measures that represent well neither pattern nor growth (mixed) are of less clinical utility than either pure pattern indices or growth indices. 6. The analytical and conceptual separation of pattern and growth seems useful in analysis of morphology, analysis of growth, prediction of growth, and clinical treatment planning.

Adolescent↗

Craniofacial growth in juvenile chronic arthritis.

The craniofacial growth in children with juvenile chronic arthritis (JCA), especially that of the mandible, and the degree of destruction of the mandibular condyles vary depending on the heterogeneity in duration and intensity of the disease. In JCA children showing destruction of the temporomandibular joint, the dentofacial morphology is characterized by overall smaller dimensions of the mandible, mandibular retrognathia, a steep mandibular plane, Class II malocclusion, dental crowding, and frontal open bite. In children with unilateral condylar destruction, asymmetries will develop, with the chin deviating to the affected side. The facial morphology of JCA children with condylar lesions becomes more abnormal during growth, reflecting a decelerated mandibular development and a backward-rotating growth pattern. The main single cause of the deviating craniofacial growth is mandibular condylar destruction. Other factors that may influence the craniofacial growth are head posture, soft tissue stretching, disease activity and drug therapy, type of onset of the disease, muscle weakness, decreased functional ability, and orthodontic treatment.

Arthritis, Juvenile↗

A longitudinal study of facial growth in Papio cynocephalus after resection of the cartilagenous nasal septum.

The present study evaluates in Papio cynocephalus the effectiveness of varying the amount of nasal septum resected and the age at surgery in an attempt to develop a technique which may have clinical value for the human condition. The analysis of interdental dimensions by graphical techniques demonstrates that a critical age exists at which total septum resection leads to maximum growth arrest of the premaxilla. Comparisons of linear regression curves for operated and control animals confirm these findings and also demonstrate the existence of sexual dimorphism in premaxillary growth rates.

Age Factors↗

The influence of lip function on the sagittal and transversal development of the maxilla in cleft patients.

Cleft patients who have undergone surgery often show considerable inhibition in the sagittal development of the mid-face after completed growth. This is partly attributed to scar contraction in the lip region following surgery. The present investigation deals with the etiological factors involved in the development disturbances caused by the cleft in the maxilla of 100 cleft patients. Particular attention was paid as to the unfavourable effect of the operated cleft lip. This was tested electromyographically and correlation between the electromyographic and the skeletal measurements was sought. Electromyographic changes in lip activity during orthodontic treatment was also investigated. The effect of these changes is discussed.

Adolescent↗

[The angulation of the base of the skull--a determining factor for facial skeletal development? The significance of the angulation of the base of the skull].

By means of tensor analysis this cephalometric study was undertaken to compare the growth differences of the facial skull of untreated orthodontic patients. We investigated children with small cranial base angle (BaSN = 128-132 degrees) and another group with an angle greater than 132 degrees. In this cross-sectional study we compared the development of the skull from an age of 7 to 8 years to an age of 9 to 10 years. In contrast to patients with small cranial base angle those with flatter base showed an increased vertical growth. The growth of the midface and mandible tend toward a retrognathic face. Angle Cl.-I cases showed a proportional horizontal growth pattern in all regions of the face.

Cephalometry↗

Dental attrition of Mayan Tzutujil children--a study based on longitudinal materials.

The purpose of this study was to evaluate dental attrition by measuring attrition volume on all types of teeth during facial growth, tooth shedding and eruption. Dental casts and cephalograms of 7 male and 7 female Mayan Tzutujil Indian children were used. Relationships were found between increase in vertical and horizontal facial growth and increase in attrition on the deciduous canines, first and second molars, permanent incisors and first molars in both arches and in both sexes. Significant increases in attrition were found on the deciduous second molars during eruption of the permanent first molars, and on the permanent incisors and first molars during eruption of the second molars in both arches and in both sexes. The results suggest that the function of attrition is 1) to compensate for increase in vertical and horizontal dimensions during facial growth, and 2) to adjust the occlusal surfaces during tooth eruption and occlusal development. In addition, an attritional index was developed to evaluate attrition among teeth. This index could be used in the future to make comparisons among different populations. Comparisons were made among Class I, II and III molar relations by using the attritional index, showing how it can be used to gain a better understanding of the characteristic patterns of dental attrition.

Adolescent↗

New developments in genioplasty: functional versus cosmetic.

Since the orthodontist is frequently the first clinician to be consulted for dentofacial deformity, an awareness of potential surgical procedures available to correct such deformities is imperative. Despite the fact that isolated genioplasty is becoming rare, the role the procedure plays in corrective jaw surgery is not diminished. Functional and cosmetic aspects must be considered in case planning and the flexibility of the procedure lends itself well to deformity correction in all three dimensions.

Chin↗