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PubMed1984

Genetic and epigenetic control of connective tissues in the craniofacial structures.

The connective tissues of the craniofacial region can neither develop nor be maintained independently of their local environment. I have stressed such epigenetic control in the present brief review of the origin, differentiation, morphogenesis, and growth of selected craniofacial tissues. I began by discussing the origin of these tissues in the neural crest. The extensive migration of neural crest cells to form the craniofacial region of the embryo is epigenetically regulated by extracellular matrix products such as fibronectin, and by basal laminae of the epithelia along which some cells migrate. The trigger which initiates differentiation of these mesenchymal cells is provided by epithelia with which they come into contact either before, during, or after migration, as illustrated by the differentiation of both Meckel cartilage and mandibular dermal bones. Subsequent differentiation of secondary cartilage is also shown to be epigenetically initiated, in this case by the mechanical environment created by muscle action. Both secondary cartilages on avian dermal bones and the condylar cartilage of the mammalian dentary are discussed. The interplay between genetic and epigenetic factors in morphogenesis and growth of craniofacial connective tissues is then very briefly discussed.

Animals↗

PubMed1991

Postnatal craniofacial skeleton development following a pushback operation of patients with cleft palate.

A longitudinal growth study of the craniofacial skeleton in 52 (19 males, 33 females) Danish individuals with cleft palates was performed. Thirty (13 males, 17 females) had clefts of the soft palate only or clefts extending into the posterior third of the hard palate. Twenty-two (6 males, 16 females) had more extensive clefts including up to two-thirds of the hard palate. The cleft was closed with a pushback operation at 22 months of age. Orthodontic treatment was included in the early mixed dentition. Lateral cephalometries were obtained at 5, 8, 12, 16, and 21 years of age. Twenty-four variables were digitized and analyzed. The results indicated that patients with more extensive clefts demonstrated significantly smaller anterior cranial base length (N-S), total cranial base length (N-Ba), maxillary dentoalveolar base length (A-PMP), mandibular length (Cd-Pgn), upper anterior and posterior facial heights (N-ANS and P-PMP), and total facial height (N-Gn). Patients with the more extensive clefts reached maximum growth spurt later than patients with less extensive clefts in all dimensions except the A-PMP and the lower and total facial heights.

Adolescent↗

PubMed1983

Superimpositional assessment of treatment-associated changes in the temporomandibular joint and the mandibular symphysis.

This article analyzes differences in the measured displacement of the condyle and of progonion when different vectors of force are delivered to the maxilla in the course of non-full-banded, Phase 1, mixed-dentition treatment for the correction of Class II malocclusion. The 238-case sample is identical to that for which changes in other parameters of facial form have been reported previously. Relative to superimposition on anterior cranial base and measured in a Frankfort-plane-determined coordinate system, we have attempted to identify and quantitate (1) the displacement of each structure which results from local remodeling and (2) the displacement of each structure which occurs as a secondary consequence of changes in other regions of the skull. We have also attempted to isolate treatment effects from those attributable to spontaneous growth and development. At the condyle, we note that in all three treatment groups and in the control group there is a small but real downward and backward displacement of the glenoid fossa. This change is not treatment induced but, rather, is associated with spontaneous growth and development. (See Fig. 5.) Some interesting differences in pattern of "growth at the condyle" were noted between samples. In the intraoral (modified activator) sample, there were small but statistically significant increases in growth rate as compared to the untreated group of Class II controls. To our surprise, similar statistically significant increases over the growth rate of the control group were noted in the cervical sample. (See Table III, variables 17 and 18.) Small but statistically significant differences between treatments were also noted in the patterns of change at pogonion. As compared to the untreated control group, the rate of total displacement in the modified activator group was significantly greater in the forward direction, while the rate of total displacement in the cervical group was significantly greater in the downward direction. There were no statistically significant differences in the rate of total displacement of pogonion between the high-pull sample and the control sample. (See Table IV, variables 21 and 22.

Activator Appliances↗

PubMed2003

Effectiveness of early orthodontic treatment with the Twin-block appliance: a multicenter, randomized, controlled trial. Part 1: Dental and skeletal effects.

This study evaluated the effectiveness of early orthodontic treatment with the Twin-block appliance for the developing Class II Division 1 malocclusion. This multicenter trial was carried out in the United Kingdom. A total of 174 children, aged 8 to 10 years old, with Class II Division 1 malocclusion were randomly allocated to receive treatment with a Twin-block appliance or to an untreated, control group. Data were collected at the start of the study and 15 months later. Results showed that early treatment with Twin-block appliances resulted in reduction of overjet, correction of molar relationships, and reduction in severity of malocclusion. Most of this correction was due to dentoalveolar change, but some was due to favorable skeletal change. Early treatment with the Twin-block appliance is effective in reducing overjet and severity of malocclusion. The small change in the skeletal relationship might not be considered clinically significant.

Age Factors↗

PubMed1992

Growth patterns in the orbital region: a morphometric study.

Data for analysis of age-related changes in growth in the intercanthal (en-en) and biocular (ex-ex) widths were obtained from 1,594 healthy North American Caucasians in age groups from 1 to 18 years, divided equally between males and females. At 1 year, the degree of development of the intercanthal width reached 84.1%, and that of the biocular width 85.9% of adults in both sexes. The levels of growth achieved by 5 years of age rose to 93.3% in the intercanthal width and 88.1% in the biocular width, in both sexes. The average total growth increments achieved between ages 1 and 18 years were 5.2 mm in the intercanthal width and 12.5 mm in the biocular. The intercanthal width showed very little growth after 1 year of age; in contrast, the biocular width showed significantly greater growth increments both before and after 5 years of age. Rapid growth was observed between 3 and 4 years in the intercanthal width of both sexes. The age-related growth observed in the biocular width was small but continuous up to maturation time. The intercanthal width reached full maturation at 8 years in females and 11 years in males, and the biocular width at 13 years in females and 15 years in males.

Adolescent↗

PubMed1986

Masticatory muscle function and craniofacial morphology. An experimental study in the growing rat fed a soft diet.

The present series of investigations was performed in order to study the relationship between masticatory function and craniofacial morphology, and to elucidate the mechanism underlying possible functional changes in the craniofacial growth in rats fed a soft diet. The experimental model chosen was comprised of young rats with altered masticatory function, induced by changing the consistency of the diet. Possible influences on the craniofacial growth were studied longitudinally by x-ray cephalometry, and the bone graft reaction in the facial skeletal regions of rats was assessed in sutures and cortical bone by vital stain, micro-radiography and routine histology. The attrition and eruption rate of the rat incisors were measured "clinically", and the effect of an increased attrition was tested cephalometrically, to see whether it influences the craniofacial growth. In order to evaluate the forces developed by the masticatory muscles the active tetanic tension was measured after electrical stimulation. The muscle fibre composition and the fibre size of the masseter and digastric muscles were examined after enzyme histochemical analysis. The craniofacial morphology and the growth pattern of the rats fed a soft diet were found to be changed to a more orthocranial one, while a decreased bone apposition was found in the angle of the mandible and the upper viscerocranium, with an alteration in the cranial sutures. The morphological changes observed were independent of the attrition and eruption rate of the rat incisors but seem to be related to the low masticatory forces developed by the rats fed a soft diet. The alteration in the "biting" force level was possibly due to the masticatory muscles changes in the muscle fibre types and the smaller size of the fibres, caused by the decreased functional demand on the rats fed a soft diet. Thus, it seems that the alteration in the masticatory function caused structural changes in the masticatory muscles, as well as changes in their contractive capacity. These may be considered as the results of prolonged centrally decided functional alteration brought about by changing the consistency of the diet. The reduced functional forces and the changes in the masticatory muscle contraction caused a low functional strain on the bone and less tension on the periosteal membrane. This tension in the periosteal membrane has also been shown to regulate the displacement of bones in the craniofacial region. The change in the masticatory function may have induced changes in the interosseous movements, which can be underlying reason for the obliterative osteogenesis in the internasal suture.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMedDate not supplied

[Heredity and environment in the genesis, epigenesis and evolution of the orofacial area].

Genetic and evolutionary aspects of the dento-facial complex are described according to the concept of heredity as a force of preservation for the human species, though ruled by natural selection and by mutational changes. Ontogenesis and growth of the oral structures reflect mutual regulations between genes and environmental factors. Therefore, the authors carry out an analysis of environmental and constitutional factors affecting dental and facial development. Three levels are identified: individual morphogenesis and growth; actual heredity of parietal dento-facial traits; role and meaning of teeth, jaws and temporo-mandibular joint during evolution leading to Homo sapiens sapiens. As far as individual development is concerned, genes provide only the input for initial cell proliferation and/or differentiation. Further on, growth and morphogenesis of oro-facial structures takes place by means of cell-to-cell and cell-to-substrate interactions. The final, structural result is due to reciprocal interactions among developing structures: muscles modify bone, teeth alignment influences bony bases alignment, ecc. Each structure is genetically determined (teeth, bones, muscles) and each structure carries out epigenetic regulations on other structures: no structure is secluded from biological function of the organism. The inheritance of oro-facial "traits", then, is hardly valuable. First of all, "traits" actually do not exist: they are the product of complex, multifactorial biological mechanisms. Moreover, facial characteristics are affected by polygenic regulation, each gene often showing pleiotropic effects. It has been calculated that 85-90% of facial dimensions in due to epigenetic modifications. Evolution and phylogenesis give evidence about the deep environmental influence on oro-facial morphology. Apart from certain molecular features regarding tooth structure (several dental proteins are today the same as those of the first Vertebrates who lived 500 millions of years ago), tooth number, form, and size depend upon environmental factors. Therefore, dentistry has the important task to preserve fundamental characteristics of dentition, and to intercept environmental pathogenetic factors, as dentition represents a precious instrument for the survival of the human species.

Biological Evolution↗

PubMed1994

Finite element analysis for stresses in the craniofacial sutures produced by maxillary protraction forces applied at the upper canines.

The purpose of this study was to investigate the nature of stress distributions in the craniofacial sutures produced by orthopaedic maxillary protraction forces applied to the upper canines. A three-dimensional finite element model of the craniofacial complex was developed for finite element analysis. An anteriorly directed force of 1.0 kg was applied to the upper canines in three different directions, i.e. parallel, 30 degrees upwards and downwards to the functional occlusal plane. Normal stresses acting on the sutural systems were greatest when force was applied in the 30 degrees upward direction. Furthermore, relatively large compressive stresses were induced in the frontonasal and frontomaxillary sutures, indicating that forward and upward rotation of the nasomaxillary complex was produced with substantial distortion of the complex, by the forces applied in both parallel and 30 degrees upward directions. A 30 degrees downward force produced almost uniform tensile stresses in the zygomaticotemporal and zygomaticomaxillary sutures, with least compressive stresses in the frontonasal and frontomaxillary sutures located in the superior region of the complex. This would indicate a uniform stretch of the nasomaxillary complex in both anterior and inferior directions, with negligible distortion of the complex and would be appropriate for accelerating natural growth of the nasomaxillary complex.

Biomechanical Phenomena↗

PubMed1982

The postnatal development of the palatomaxillary region studied on human autopsy material.

Greater understanding of the postnatal region of the maxilla is necessary if the normal growth of the maxillary complex, as well as its reaction to orthopedic forces, is to be comprehended. The area in question was studied at various stages of development, both on dry skulls and on autopsy material. The skull material demonstrated an increasing approximation between the palatal bone and the adjacent bones, the maxilla and pterygoid process. Disarticulation of the bones studied was possible only on skulls representing the infantile and earliest adolescent periods. Attempted disarticulation in the later juvenile and early adolescent periods was always accompanied by fracture of the heavily interdigitated osseous surfaces. The complexity of the articulating surfaces was studied further and, by means of quantitation of the bony surfaces, an "index of complexity" was calculated. The findings of the present study that the palatal bone acts as a "buffer" between two areas of differing intrinsic growth pattern and that the remodeling processes in the area seem to reflect different functional demands to the bony pharynx and the maxillary complex. The rigidity of the area as a result of the observed sutural complexity indicates that the center of rotation for the observed spatial changes in the maxillary complex as a result of orthopedic forces could be localized in the palatomaxillary region.

Adolescent↗

PubMed1985

Posttreatment changes of skeletal morphology following treatment aimed at restriction of maxillary growth.

In the evaluation of the success of orthodontic treatment, an analysis of posttreatment changes was essential. Twenty-eight patients with increased overjet and overbite, a high mandibular plane angle, and perioral dysfunction had been treated by means of normal maximal restriction of maxillary development. The posttreatment changes of the skeletal morphology was analyzed and related to both pretreatment morphology and treatment-produced changes. The correlation analysis demonstrated that less than 25% of the variation in posttreatment changes could be accounted for by pretreatment morphology. However, the dependency of posttreatment changes on treatment-produced changes was stronger with regard to both linear and angular measurements. Upon analyzing the changes in mandibular prognathism during and after treatment, all combinations of downward and forward growth were presented. In some cases the increase in prognathism during treatment would continue after treatment; in others the reverse was true. Opening of the Y axis would in some cases be constant, leading to a decrease in mandibular prognathism. In others a pronounced anterior rotation moved the pogonion forward following treatment. A dental relapse as a consequence of skeletal relapse was seen only in cases in which normal perioral function, including normal lip closure and absence of tongue-thrust swallowing, had not been established.

Adolescent↗

PubMed1997

Differential growth and maturation in idiopathic growth-hormone-deficient children.

This study describes and compares the growth and maturation of idiopathic growth hormone deficiency (IGHD) and evaluates the potential effects of growth hormone therapy. The sample includes 40 idiopathic growth-hormone-deficient children grouped according to duration of growth hormone replacement therapy. Somatic and craniofacial development, skeletal maturation and dental maturation were evaluated and compared. The results showed consistent delays in the maturity indices for IGHD children. Height age displayed the greatest delay (3 years) followed by skeletal age (2.2 years) and dental age (0.8 years). Overall craniofacial growth deficiencies were also demonstrated. Anterior cranial base and mandibular length were most affected; posterior cranial base length and facial heights were least affected. Analysis of covariance, controlling for the starting age of therapy, showed significant differences between children grouped according to duration of growth hormone therapy. Catch-up growth with hormonal therapy was established for height, facial height, skeletal age and posterior cranial base length. It was concluded that the various craniofacial skeletal components have different potentials for growth retardation with IGHD; catch-up growth following growth hormone replacement therapy was greatest for the components with the greatest initial (or baseline) growth potential.

Adolescent↗

PubMed1997

Maxillary development revisited: relevance to the orthopaedic treatment of Class III malocclusions.

Normal development of the maxilla results not only from movements of its constituent skeletal units and bony apposition-resorption superficially, but also from the specific development of the antero-lateral regions. In Class III cases, correction of the skeletal dysmorphosis requires not only that the maxilla is in a correct position (in relation to the mandible) and that the correct occlusion is achieved, but also that there is good development of the exo-peri-premaxilla. This requires normalization of muscular posture (labio-mental, lingual, velo-pharyngeal) and of orofacial functions (nasal ventilation, swallowing, mastication). Postero-anterior traction using an orthopaedic mask can only accomplish part of the treatment of Class III. The action must always be complimented by other therapy aimed at correcting the underdevelopment of the antero-lateral regions. Facemask therapy is not only simple sagittal distraction, but is truly a method for treatment of Class III which is well understood and achieves excellent results. Taking into account the great diversity of anatomical forms of Class III malocclusion, it is not surprising that extra-oral postero-anterior traction gives widely varying results. The quality, however, depends principally on the method used. Orthodontists must not hesitate to call for the assistance of a surgeon each time the functional treatment is insufficient, particularly in cleft patients where the results depend more on surgical procedures, both primary and secondary, than on dentofacial orthopaedics.

Adolescent↗

PubMed2006

Neuroteratogens in man: an overview with special emphasis on the teratogenicity of antiepileptic drugs in pregnancy.

The most active growth and development of the human cerebrum and cerebellum occurs in the second half of pregnancy and in the first year of life. It is therefore not surprising that many teratogens may also affect development causing slight, moderate or even severe brain damage. The "classical" antiepileptic drugs (AEDs) valproic acid (VPA), phenytoin, phenobarbital, primidone and carbamazepine are all considered to be teratogenic. They may increase the rate of major congenital anomalies including neural tube defects (NTD), cause specific facial and other dysmorphic features--the "Anti Epileptic Drug Syndrome" (AEDS) and often some degree of mental impairment. Of these AEDs, the most teratogenic seems to be valproic acid, causing about 2% of NTD and an additional increase of 4-8% in major congenital anomalies. Phenytoin also increases the rate of various anomalies, but apparently not of NTD. Phenobarbital primidone and carbamazepine are also teratogenic and impair intellectual function but to a lesser extent than VPA and phenytoin. Cognition is mainly impaired in the children that also exhibit the AEDS. The impairment is slight to moderate, leaving the affected children with a close to borderline intelligence. Lamotrigine monotherapy in pregnancy seems to be relatively safe. In general, polytherapy is more dangerous to the fetus than monotherapy and, at least for VPA and lamotrigine, there seems to be a "threshold effect".

Abnormalities, Drug-Induced↗

PubMed2004

Management of craniofacial development in the Parry-Romberg syndrome: report of two patients.

OBJECTIVE: The aim of this article is to describe the orthodontic therapy for Parry-Romberg syndrome. The therapeutic goal is to minimize the wasting effects of progressive atrophy on facial development of a part of the face. DESIGN: To correct problems affecting craniofacial development of these patients, occurring during puberty, an orthodontic appliance was employed, which helps maintain parallelism of the facial planes, in particular the mandibular plane. SETTING: Orthodontic care was carried out in the Dental Clinic of the Catholic University of the Sacred Heart of Rome. INTERVENTION: Two patients underwent orthodontic therapy for 6 years. Appliances were checked every month and modified periodically so as to adapt to facial bone growth. RESULTS: At the end of craniofacial growth, the mandible was almost symmetric and the problem relating to atrophy remained confined to the initial area. Cephalometric analyses demonstrated that the occlusal plane and the mandibular plane maintained a straight orientation in relation to the bizygomatic plane. The ratio between the left and right side of the ramus and condyle, in the mandible, improved. CONCLUSIONS: The use of orthodontic therapy allows patients affected by hemifacial progressive atrophy to present a more harmonic face at the end of puberty when final reconstruction can be planned. These results provide for a limitation of surgical intervention to the sclerodermic area alone.

Adolescent↗

PubMed1976

Biology of the rice rat (Oryzomys palustris natator) in a laborabory environment. X. Postweaning growth of the skull.

A survey of skull development of the rice rat (Oryzomys palustris natator) covering a period of 21 days to 16 months involving equal numbers of males and females (108) was undertaken using various skull parameters. Sexual dimorphism in relation to body weight and length emerged before that of the skull which was only clearly marked by 2 months. A number of the skull parameters by virtue of their individual growth potential did not show sexual differences in size for a long time, whereas others were clearly marked. Once the differences between the sexes had been established they were maintained. One parameter - lenght of cranium - represents those parameters which show changes and it was found that the male rat continued to show a steady linear increase in length up to 16 months, whereas the female cranial length shows a deceleration with termination around 12 months. The skull differences are mirrored in the weight and length findings and it suggested that the earlier sexual maturity of the females is compensated by an earlier cessation of growth compared to the males which mature later and have a correspondingly later cessation.

Animals↗

PubMed1976

Postnatal development of the human temporomandibular joint. I. A histological study.

Temporomandibular joints from 61 humans, aged 2 days to 27 years, were examined histologically. Four layers of the condyle were studied in detail. The outermost layer was richly vascularised in new-borns but by 3 years of age it had become avascular and contained few cells. In neonates the cartilage layer constituted a large part of the condyle but soon decreased in thickness and by 5-6 years of age it constituted only a thin zone of the top of the condyle. In the proliferative zone, mitoses occurred up to 13-15 years of age. This zone then decreased in thickness; the number of cells decreased, while the amount of intercellular substance increased. At birth, the temporal component was flat and was lined by vascularised connective tissue which became richer in collagen with increasing age. The cartilage layer was lacking in the fossa but was present on the tuberculum. A proliferative zone in this cartilage could be seen up to the age of 17-18 years and cartilage having only few cells was found in adults. Remodelling processes were seen in all components of the joints. The significance of the remodelling seen in the fossa and on the mandibular neck is discussed with relation to condylar and periosteal growth of the mandible.

Adolescent↗

PubMed1995

[The significance of preventive CNS irradiation during antineoplastic therapy in childhood with regard to late odontogenic and mandibulofacial injuries].

The aim of the present study was to determine the adverse effects of antineoplastic chemotherapy and radiotherapy on tooth development, i.e., on dentition in general and on craniofacial growth. The patients studied consisted of 26 children with solid tumors treated with chemotherapy alone and 34 patients with acute lymphoblastic leukemia (ALL) who were treated with intensive and follow-on radiation therapy (18 and 24 Gy) to the neurocranium as a constituent of central nervous system prophylactics in treatment protocols for ALL. The treatment protocol employed in these children is known as the BFM (Berlin, Frankfurt, Münster) protocol. At the time of diagnosis the children ranged in age from 3 to 52 months. All treated patients had microdontia, enamel dysplasia, thinning and tapering of apical roots portions, and marked shortening of the roots. These defects were more pronounced in children treated for ALL, but it was not possible to establish statistically relevant evidence on the influence of adjuvant radiotherapy in this group. This indicates that there is a catch up in craniofacial growth 9 years after therapy and that the most serious long-term adverse effects are on dentition.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1985

Longitudinal soft-tissue profile changes: a study of three analyses.

The purpose of this study is to describe the changes in six soft-tissue parameters that are commonly used by orthodontists in their diagnosis and treatment planning as well as in the evaluation of profile changes that occur with growth and orthodontic treatment. The parameters evaluated were two angles of facial convexity, the Holdaway soft-tissue angle, Merrifield's Z angle, and Rickett's esthetic line and lip relationships. The subjects of this study consisted of 20 males and 15 females for whom lateral cephalograms taken between the ages of 5 and 25 years were available. Descriptive statistics for the absolute and incremental changes are presented on a yearly basis between the ages of 5 and 17 years and at adulthood. Growth profile curves were constructed for each parameter, and regression equations were developed to describe the age-related changes in the six parameters for both males and females. The present findings indicated that the male and female growth profile curves were significantly different, except for the angle of facial convexity (excluding the nose) and Merrifield's Z angle. One of the conclusions that can be derived from this investigation is that the two angles of soft-tissue facial convexity, the Holdaway soft-tissue angle, and Merrifield's Z angle do not behave in a similar manner with age. Therefore, the clinician needs to use a number of soft-tissue parameters to better evaluate the soft-tissue profile. A limited number of cephalometric standards have been identified for each parameter. These standards can be used by the orthodontist as representative of the change between the age of 5 years and adulthood. This should enable the orthodontist to treat the patient to soft-tissue norms that are age- and sex-specific, rather than to an adult standard.

Adolescent↗