Craniofacial growth in short children born small for gestational age: effect of growth hormone treatment

The Implications of Endocrinology in Orthodontics – Literature Review

Endocrinopathies have a variety of orofacial presentations which span from dental malocclusion to facial disfigurement. These characteristics depend on the nature and severity of the condition. An orthodontist should understand the body’s physiological processes to be able to timely determine the optimum intervention and plan treatment stages accordingly in compromised individuals. Communication between the two specialties should be well coordinated and should help facilitate quality health care to the patient. This review was aimed to impart the basic knowledge and the pivotal guidelines for orthodontic management in these conditions. Systemic conditions require multidisciplinary management and the dental team should aim to provide quality oral health care to enhance the overall quality of life and the orthodontist plays a vital role in helping patients achieve physical and psychological health.

Effects of Low-Intensity Pulsed Ultrasound Therapy on the Temporomandibular Joint Complex in Conjunction With a Fixed Functional Appliance: A Prospective 3-Dimensional Cone Beam Computed Tomographic Study

OBJECTIVES

This prospective study aimed to analyze 3-dimensional changes in the temporomandibular joint (TMJ) complex with a synergistic effect of functional jaw orthopedics using a fixed functional appliance and low-intensity pulsed ultrasound (LIPUS) therapy.

METHODS

Forty patients with skeletal class II malocclusion were randomly assigned to 4 groups (2 control groups and 2 test groups) of 10 patients each. After insertion of the fixed functional appliance, the test group was stimulated with LIPUS therapy in the TMJ region bilaterally for 20 minutes daily for first 10 days and thereafter at least 3 times per week until complete mandibular advancement was achieved. Three-dimensional images obtained with a cone beam computed tomographic scanner were used to analyze the changes in the TMJ complex at the prefunctional stage and after completion of functional appliance therapy. Direct intragroup and intergroup comparisons for different morphometric variables were conducted with the Student t test.

RESULTS

The 40 patients included 20 male and 20 female patients between the ages of 12 and 16 years (mean age ± SD, 13.2 ± 1.8 years). Both the test groups and the control groups showed statistically significant variable changes in condylar head position and morphometric changes in relation to the joint space analysis (mean differences, -1.000 and -1.080 mm; P < .05). However, no significant differences were found during the intergroup comparisons at the prefunctional and postfunctional stages for the variables examined, except for the measurements of the linear distance of the condyle to the external auditory meatus on both the right and left sides at the prefunctional phase.

CONCLUSIONS

Low-intensity pulsed ultrasound therapy positively affects the quantum of the joint space, thus proving to be a promising adjunct in enhancing treatment outcomes of functional jaw orthopedics in growing patients with skeletal class II malocclusions.

Fixed-functional appliance treatment combined with growth hormone therapy

The purpose of this study was to illustrate the effects of growth hormone (GH) therapy and fixed functional appliance treatment in a 13-year-old Class II malocclusion patient without GH deficiency. GH has been shown to effectively increase endochondral growth and induce a more prognathic skeletal pattern. Although a major concern in Class II retrognathic patients is chin deficiency, long-term studies have shown that the mandibular growth enhancement effects of functional appliances are clinically insignificant. This case report demonstrates that the mandible grew significantly during fixed functional appliance treatment combined with GH therapy, with stable results during 2 years 11 months of retention. More studies are needed to evaluate GH therapy as a supplement in Class II treatment.

Long-term follow-up of a patient with achondroplasia treated with an orthodontic approach

We successfully treated a patient with achondroplasia with conventional orthodontic techniques. It was followed by long-term retention. The patient, a 12-year-old boy, had chief complaints of occlusal disturbance and mandibular protrusion. He had been diagnosed with achondroplasia and had growth hormone treatment in his early teenage years. His facial profile was concave with a bulging forehead and a retrognathic maxilla. It was characterized by a skeletal Class III jaw-base relationship with a retropositioned maxilla. At the age of 12 years 9 months, maxillary protraction was initiated with a reverse headgear; for 2 years 6 months, the maxillomandibular growth was controlled. After the growth spurt, at the age of 15 years 6 months, leveling and alignment of both dental arches were started with preadjusted edgewise appliances. After 83 months of multibracket treatment, an acceptable occlusion with a Class I molar relationship and an adequate interincisal relationship was achieved, despite the simultaneous marked vertical growth of the mandible. The resultant occlusion was stable during a 6-year retention period, although considerable forward-downward mandibular growth was observed. Conclusively, our results indicated the necessity of long-term observation in this patient with achondroplasia, especially because of the persistent mandibular growth.

Effect of growth hormone treatment on craniofacial growth in children: Idiopathic short stature versus growth hormone deficiency

BACKGROUND/PURPOSE

Few studies have evaluated craniofacial growth in boys and girls with idiopathic short stature (ISS) during growth hormone (GH) treatment. The aim of this study was to evaluate the effect of GH treatment on craniofacial growth in children with ISS, compared with those with growth hormone deficiency (GHD).

METHODS

This study included 36 children (mean age, 11.3 ± 1.8 years) who were treated with GH consecutively. Lateral cephalograms were analyzed before and 2 years after start of GH treatment.

RESULTS

There were no significant differences in age and sex between ISS and GHD groups and the reference group from semilongitudinal study (10 boys and 8 girls from each group). Before treatment, girls with ISS showed a skeletal Class II facial profile compared with the GHD and reference groups (p = 0.003). During GH treatment, the amount of maxillary length increased beyond norm in the ISS and GHD groups in boys (p = 0.035) > 3 standard deviation score (SDS). Meanwhile, mandibular ramus height (p = 0.001), corpus length, and total mandibular length (p = 0.007 for both) increased more in girls with ISS than in girls with GHD. Lower and total anterior facial heights increased more in girls with ISS than in girls with GHD (p = 0.021 and p = 0.007, respectively), > 7-11 SDS.

CONCLUSION

GH should be administered carefully when treating girls with ISS, because GH treatment has great effects on vertical overgrowth of the mandible and can result in longer face.

Growth hormone positive effects on craniofacial complex in Turner syndrome

OBJECTIVE

Turner syndrome occurs in phenotypic females with complete or partial absence of X chromosome. The leading symptom is short stature, while numerous but mild stigmata manifest in the craniofacial region. These patients are commonly treated with growth hormone to improve their final height. The aim of this study was to assess the influence of long-term growth hormone therapy on craniofacial morphology in Turner syndrome patients.

DESIGN

In this cross-sectional study cephalometric analysis was performed on 13 lateral cephalograms of patients with 45,X karyotype and the average age of 17.3 years, who have received growth hormone for at least two years. The control group consisted of 13 Turner syndrome patients naive to growth hormone treatment, matched to study group by age and karyotype. Sixteen linear and angular measurements were obtained from standard lateral cephalograms. Standard deviation scores were calculated in order to evaluate influence of growth hormone therapy on craniofacial components.

RESULTS

In Turner syndrome patients treated with growth hormone most of linear measurements were significantly larger compared to untreated patients. Growth hormone therapy mainly influenced posterior face height, mandibular ramus height, total mandibular length, anterior face height and maxillary length. While the increase in linear measurements was evident, angular measurements and facial height ratio did not show statistically significant difference. Acromegalic features were not found.

CONCLUSIONS

Long-term growth hormone therapy has positive influence on craniofacial development in Turner syndrome patients, with the greatest impact on posterior facial height and mandibular ramus. However, it could not compensate X chromosome deficiency and normalize craniofacial features.

Growth Hormone and Craniofacial Tissues. An update

Growth hormone is an important regulator of bone homeostasis. In childhood, it determines the longitudinal bone growth, skeletal maturation, and acquisition of bone mass. In adulthood, it is necessary to maintain bone mass throughout life. Although an association between craniofacial and somatic development has been clearly established, craniofacial growth involves complex interactions of genes, hormones and environment. Moreover, as an anabolic hormone seems to have an important role in the regulation of bone remodeling, muscle enhancement and tooth development. In this paper the influence of growth hormone on oral tissues is reviewed.

New therapeutics in promoting and modulating mandibular growth in cases with mandibular hypoplasia

Children with mandibular growth deficiency may develop airway obstruction. The standard treatment of severe airway obstruction involves invasive procedures such as tracheostomy. Mandibular distraction osteogenesis has been proposed in neonates with mandibular deficiency as a treatment option to avoid tracheostomy procedure later in life. Both tracheostomy and distraction osteogenesis procedures suffer from substantial shortcomings including scarring, unpredictability, and surgical complications. Forward jaw positioning appliances have been also used to enhance mandible growth. However, the effectiveness of these appliances is limited and lacks predictability. Current and future approaches to enhance mandibular growth, both experimental and clinical trials, and their effectiveness are presented and discussed.

Growth hormone therapy and craniofacial bones: a comprehensive review

Growth hormone (GH) has significant effects on linear bone growth, bone mass and bone metabolism. The primary role of GH supplementation in children with GH deficiency, those born small for gestational age or with other types of disorders in somatic development is to increase linear growth. However, GH therapy seems to elicit varying responses in the craniofacial region. Whereas the effects of GH administration on somatic development are well documented, comparatively little is known of its effects on the craniofacial region. The purpose of this review was to search the literature and compile results from both animal and human studies related to the impact of GH on craniofacial growth.

Growth of functional cranial components in rats with intrauterine growth retardation after treatment with growth hormone

The goal of this study was to analyse the effect of growth hormone (GH) on catch-up growth of functional facial (splanchnocranial) and neurocranial components in rats with intrauterine growth retardation (IUGR). Wistar rats were divided into the following groups: control (C), sham-operated (SH), IUGR, and IUGR + GH. IUGR was surgically induced and GH was administered between 21 and 60 days of age. Radiographs were obtained at 1, 21, 42, 63, and 84 days of age in order to measure length, width, and height of neurocranium (NL, NW, and NH) and face length, width, and height (FL, FW, and FH). Analysis of variance was performed at 1 day of age and a principal components analysis (PCA) at 84 days of age. Neurocranial and facial volumetric indexes were calculated as NVI = (3)√NL × NW × NH and FVI = (3)√FL × FW × FH, respectively, and adjusted by non-linear regression analysis. On postnatal day 1, there were significant differences between SH and IUGR (P < 0.01). Also, in both genders, final neurocranial volume was similar between SH and IUGR + GH groups, while the IUGR group had the lower value (P < 0.01). Final facial volume was similar among the three groups. In both genders, facial growth rates were SH = IUGR > IUGR + GH (P < 0.01). The first axis of the PCA exhibited size effect and the second axis showed shape effect. Reductions of placental blood flow modify cranial growth. The functional neurocranial and facial components in rats with IUGR presented different recovery strategies through modular behaviour, mainly related to modifications of growth rate as response to GH administration.

Ontogenetic changes of craniofacial complex in Turner syndrome patients treated with growth hormone

OBJECTIVE

The present study assessed changes of craniofacial complex in Turner syndrome (TS) patients treated with growth hormone (GH) during development. The objective was to examine the growth rate and pattern of craniofacial structures and to establish effects of GH on craniofacial development.

MATERIALS AND METHODS

The study population consisted of 15 TS patients treated with GH aged 5-18.5 years (13.3 ± 4.4) and corresponding control group of 45 females aged 6.8-18.7 (11.4 ± 2.6). According to the stage of cervical vertebral maturation, subjects were categorized into pre-growth (5 TS and 15 controls) and growth (10 TS and 30 controls) subgroups. The cephalometric analysis comprised angular and linear variables, measured on lateral cephalometric radiographs.

RESULTS

The mandibular corpus/anterior cranial base ratio increased significantly only in controls during development. In growth period, ramus/corpus ratio was significantly larger in TS group. SNA and SNB angles were significantly smaller in TS growth subgroup compared to corresponding controls. Among other variables, no statistically significant differences were revealed.

CONCLUSIONS

In TS patients treated with GH, growth capacities of cranial base and maxilla are adequate which can be attributed to GH treatment. Shape of mandible is altered due to decreased growth of corpus and overdeveloped ramus. Both maxillary and mandibular retrognathism are becoming more expressed during development.

CLINICAL RELEVANCE

Favorable influence of GH on craniofacial complex growth rate and altered growth pattern revealed in this study should be considered while planning both orthodontic treatment and retention.

Cephalometric features in isolated growth hormone deficiency

OBJECTIVE

To analyze cephalometric features in adults with isolated growth hormone (GH) deficiency (IGHD).

MATERIALS AND METHODS

Nine adult IGHD individuals (7 males and 2 females; mean age, 37.8 ± 13.8 years) underwent a cross-sectional cephalometric study, including 9 linear and 5 angular measurements. Posterior facial height/anterior facial height and lower-anterior facial height/anterior facial height ratios were calculated. To pool cephalometric measurements in both genders, results were normalized by standard deviation scores (SDS), using the population means from an atlas of the normal Brazilian population.

RESULTS

All linear measurements were reduced in IGHD subjects. Total maxillary length was the most reduced parameter (-6.5 ± 1.7), followed by a cluster of six measurements: posterior cranial base length (-4.9 ± 1.1), total mandibular length (-4.4 ± 0.7), total posterior facial height (-4.4 ± 1.1), total anterior facial height (-4.3 ± 0.9), mandibular corpus length (-4.2 ± 0.8), and anterior cranial base length (-4.1 ± 1.7). Less affected measurements were lower-anterior facial height (-2.7 ± 0.7) and mandibular ramus height (-2.5 ± 1.5). SDS angular measurements were in the normal range, except for increased gonial angle (+2.5 ± 1.1). Posterior facial height/anterior facial height and lower-anterior facial height/anterior facial height ratios were not different from those of the reference group.

CONCLUSIONS

Congenital, untreated IGHD causes reduction of all linear measurements of craniofacial growth, particularly total maxillary length. Angular measurements and facial height ratios are less affected, suggesting that lGHD causes proportional blunting of craniofacial growth.

Growth hormone treatment does not affect incidences of middle ear disease or hearing loss in infants and toddlers with Turner syndrome

CONTEXT

No randomized, controlled, prospective study has evaluated the effect of growth hormone (GH) on the rates of middle ear (ME) disease and hearing loss in girls with Turner syndrome (TS).

DESIGN

A 2-year, prospective, randomized, controlled, open-label, multicenter, clinical trial ('Toddler Turner Study'; August 1999 to August 2003) was carried out.

SETTING

The study was conducted at 11 US pediatric endocrine centers.

SUBJECTS

Eighty-eight girls with TS, aged 9 months to 4 years, were enrolled.

INTERVENTION

The interventions comprised recombinant GH (50 microg/kg/day, n = 45) or no treatment (n = 43) for 2 years.

MAIN OUTCOME MEASURES

The outcome measures included occurrence rates of ear-related problems, otitis media (OM) and associated antibiotic treatments, tympanometric assessment of ME function and hearing assessment by audiology.

RESULTS

At baseline, 57% of the girls (mean age = 1.98 +/- 1.00 years) had a history of recurrent OM, 33% had undergone tympanostomy tube (t-tube) insertion and 27% had abnormal hearing. There was no significant difference between the treatment groups for annual incidence of OM episodes (untreated control: 1.9 +/- 1.4; GH-treated: 1.5 +/- 1.6, p = 0.17). A quarter of the subjects underwent ear surgeries (mainly t-tube insertions) during the study. Recurrent or persistent abnormality of ME function on tympanometry was present in 28-45% of the girls without t-tubes at the 6 postbaseline visits. Hearing deficits were found in 19-32% of the girls at the annual postbaseline visits. Most of these were conductive deficits, however, 2 girls had findings consistent with sensorineural hearing loss, which was evident before 3 years of age.

CONCLUSIONS

Ear and hearing problems are common in infants and toddlers with TS and are not significantly influenced by GH treatment. Girls with TS need early, regular and thorough ME monitoring by their primary care provider and/or otolaryngologist, and at least annual hearing evaluations by a pediatric audiologist.

Abnormal mandibular growth and the condylar cartilage

Deviations in the growth of the mandibular condyle can affect both the functional occlusion and the aesthetic appearance of the face. The reasons for these growth deviations are numerous and often entail complex sequences of malfunction at the cellular level. The aim of this review is to summarize recent progress in the understanding of pathological alterations occurring during childhood and adolescence that affect the temporomandibular joint (TMJ) and, hence, result in disorders of mandibular growth. Pathological conditions taken into account are subdivided into (1) congenital malformations with associated growth disorders, (2) primary growth disorders, and (3) acquired diseases or trauma with associated growth disorders. Among the congenital malformations, hemifacial microsomia (HFM) appears to be the principal syndrome entailing severe growth disturbances, whereas growth abnormalities occurring in conjunction with other craniofacial dysplasias seem far less prominent than could be anticipated based on their often disfiguring nature. Hemimandibular hyperplasia and elongation undoubtedly constitute the most obscure conditions that are associated with prominent, often unilateral, abnormalities of condylar, and mandibular growth. Finally, disturbances of mandibular growth as a result of juvenile idiopathic arthritis (JIA) and condylar fractures seem to be direct consequences of inflammatory and/or mechanical damage to the condylar cartilage.

Dento-craniofacial phenotypes and underlying molecular mechanisms in hypohidrotic ectodermal dysplasia (HED): a review

The hypohidrotic ectodermal dysplasias (HED) belong to a large and heterogeneous nosological group of polymalfomative syndromes characterized by dystrophy or agenesis of ectodermal derivatives. Molecular etiologies of HED consist of mutations of the genes involved in the Ectodysplasin (EDA)-NF-kappaB pathway. Besides the classic ectodermal signs, craniofacial and bone manifestations are associated with the phenotypic spectrum of HED. The dental phenotype of HED consists of various degrees of oligodontia with other dental abnormalities, and these are important in the early diagnosis and identification of persons with HED. Phenotypic dental markers of heterozygous females for EDA gene mutation-moderate oligodontia, conical incisors, and delayed dental eruption-are important for individuals giving reliable genetic counseling. Some dental ageneses observed in HED are also encountered in non-syndromic oligodontia. These clinical similarities may reflect possible interactions between homeobox genes implicated in early steps of odontogenesis and the Ectodysplasin (EDA)-NF-kappaB pathway. Craniofacial dysmorphologies and bone structural anomalies are also associated with the phenotypic spectrum of persons with HED patients. The corresponding molecular mechanisms involve altered interactions between the EDA-NF-kappaB pathway and signaling molecules essential in skeletogenic neural crest cell differentiation, migration, and osteoclastic differentiation. Regarding oral treatment of persons with HED, implant-supported prostheses are used with a relatively high implant survival rate. Recently, groundbreaking experimental approaches with recombinant EDA or transgenesis of EDA-A1 were developed from the perspective of systemic treatment and appear very promising. All these clinical observations and molecular data allow for the specification of the craniofacial phenotypic spectrum in HED and provide a better understanding of the mechanisms involved in the pathogenesis of this syndrome.

A longitudinal study of craniofacial growth in idiopathic short stature and growth hormone-deficient boys treated with growth hormone

The aim of this prospective, longitudinal, controlled study is to describe the long-term safety and efficacy of growth hormone (GH) administration on craniofacial morphology in boys with short stature. Forty-six boys, who started GH treatment at the Department of Paediatrics Göteborg Paediatric Growth Research Centre, were consecutively included in the study. Twenty-five boys were classified as growth hormone-deficient (GHD) and 21 as idiopathic short stature (ISS). The patients were injected with 33 (n=31) or 67 (n=15) microg GH/kg body weight/day. The mean age at the start of treatment was 11.8 years [standard deviation (SD) 1.7]. To assess craniofacial growth, standard lateral cephalometric radiographs were obtained at the start of GH treatment, annually during 4 years, and at the end of GH treatment or when growth was less than 1 cm/year. The mean follow-up period was 6.4 years (SD 1.4). Growth changes were compared with boys from a semi-longitudinal reference group of 130 healthy subjects, 7-21 years of age. t-tests for independent and paired samples and multiple regression analysis were applied. Age- and gender-specific standard deviation scores for the cephalometric variables were calculated. Repeated measures analysis of variance was used to identify significant covariates over time, such as low/high GH dose and GHD/ISS and orthodontic treatment. During the study period, eight (out of 40) boys were treated with fixed orthodontic appliances, three with functional appliances (activators), and three with other appliances (plates and lingual arches). During GH treatment period, an overall enhancement in growth of the facial skeleton was observed in boys with short stature. The changes induced by GH yielded a more prognathic growth pattern, a more anterior position of the jaws in relation to the cranial base, and increased anterior rotation of the mandible. The mandibular corpus length and anterior face height of the GH-treated boys were greater at the end of the study compared with the boys in the reference group. No differences in growth response were noted either between the GHD and ISS boys or between those treated with either 33 (low dose) or 67 (high dose) microg GH/kg body weight/day. The only change that remained significantly correlated with orthodontic treatment was the alteration in mandibular ramus height, showing a larger change in the boys who had not undergone orthodontic therapy. The findings of this study demonstrate that GH treatment has a favourable influence on the craniofacial growth pattern of boys with short stature without acromegalic features.

Effects of growth hormone on craniofacial growth

OBJECTIVE

This study determined the effects of growth hormone (GH) therapy on craniofacial growth in idiopathic growth hormone deficiency (GHD).

MATERIALS AND METHODS

Fifty-seven patients (33 boys and 24 girls; age range 4.5 to 16.7 years) with GHD were investigated and categorized into three groups according to the duration of GH therapy: the untreated group, the short-term therapy group, and the long-term therapy group. Their lateral cephalometric radiographs were studied, and craniofacial measurements were assessed by age and sex by using matched standard deviation scores.

RESULTS

In the untreated group, the anterior cranial base, total facial height, maxillary length, mandibular total length, mandibular body length, and ramus height were smaller than the standard values. In comparison with the untreated group, the long-term therapy group had a significantly larger upper facial height (P < .05), maxillary length (P < .01), and ramus height (P < .01) measurements.

CONCLUSIONS

Children who received long-term GH replacement therapy showed increased growth of the craniofacial skeleton, especially the maxilla and ramus. These findings suggest that GH accelerates craniofacial development, which improves occlusion and the facial profile.

Craniofacial growth in growth hormone-deficient rats after growth hormone supplementation

INTRODUCTION

Growth hormone (GH) supplementation is an established therapy to increase stature in GH-deficient or short-for-age children, but comparatively little is known of its effects on the craniofacial skeleton.

METHODS

Using a mutant strain of Lewis rats (dw/dw) in which GH levels were 6% to 10% of normal, but other trophic hormones were unaffected, we investigated the differential susceptibility of craniofacial measures to GH supplementation, characterized their potential for partial or complete catch-up growth, and compared their growth changes with those in long bones. At 24 days of age and for 3 subsequent weeks, radiographs of the lateral head, upper limb, and lower limb were obtained from 3 groups of growing rats (n = 8-9 in each group): dwarf (experimental) with GH injection, dwarf (sham) with vehicle injection, and wild type (control) with vehicle injection. The x-ray images were scanned, standardized points digitized, and linear distances measured. Absolute growth curves were generated for each group by using multilevel modeling procedures and iterative generalized least-squares curve fitting.

RESULTS

For every measure, growth differences were evident between the experimental and the sham groups, but the treatment effect varied inversely with relative maturity of the measure. Although all craniofacial measures showed some catch-up growth, only 31% of craniofacial measures had complete catch-up compared with all limb measures. The percentage of catch-up varied inversely with relative maturity of the measure. Our results suggest that the effects of GH supplementation vary considerably, so that measures with the lowest relative maturity (greatest baseline potential) show the greatest treatment effect and catch-up, whereas more mature measures show less growth response to GH replacement.

CONCLUSIONS

These results suggest that, depending on the timing of GH supplementation, there is potential for change in proportions or shape of the craniofacial complex.

Influence of growth hormone on the craniofacial complex of transgenic mice

Growth hormone (GH) secretion affects bone and cartilage physiology. This study investigated the effect of GH on the size of the craniofacial structures and their angular relationship. Three different models of mice with a genetically altered GH axis were used: GH excess (giant), dwarf GH antagonist (dwarf-Ant), and dwarf GH receptor knockout (dwarf-KO) mice. Each model was compared with the corresponding wild type (Wt). Five craniofacial distances were analysed: craniofacial length, upper face height, mandibular anterior height, mandibular ramus length, and mandibular corpus length. In addition, upper and lower incisor lengths and four angular relationships, nasal bone with cranial base, maxillary plane with cranial base, mandibular plane with cranial base, and the angle of the mandible, were determined. Data were analysed by one-way ANOVA. Craniofacial length, upper face height and mandibular corpus length were significantly increased in the giant mice and significantly reduced in the dwarf mice. Mandibular anterior height and mandibular ramus length were significantly affected in the dwarf-KO mice but not in the giant mice. The length of both the upper and lower incisors was significantly increased and reduced in the giant and dwarf-KO mice, respectively. In addition, the angle of the mandible was significantly increased in the giant mice and significantly reduced in the dwarf mice. It is concluded that GH plays a major role in the growth and development of the craniofacial complex by directly and indirectly modulating the size and the angular relationships of the craniofacial structures, including the incisor teeth.

Influence of growth hormone on the mandibular condylar cartilage of rats

Growth hormone (GH) stimulates mandibular growth but its effect on the mandibular condylar cartilage is not well understood.

OBJECTIVE

This study was designed to understand the influence of GH on mitotic activity and on chondrocytes maturation. The effect of GH on cartilage thickness was also determined.

DESIGN

An animal model witt differences in GH status was determined by comparing mutant Lewis dwarf rats with reduced pituitary GH synthesis (dwarf), with normal rats and dwarf animals treated with GH. Six dwarf rats were injected with GH for 6 days, while other six normal rats and six dwarf rats composed other two groups. Mandibular condylar tissues were processed and stained for Herovici's stain and immunohistochemistry for proliferating cell nuclear antigen (PCNA) and alkaline phosphatase (ALP). Measurements of cartilage thickness as well as the numbers of immunopositive cells for each antibody were analysed by one-way analysis of variance.

RESULTS

Cartilage thickness was significantly reduced in the dwarf animals treated with GH. PCNA expression was significant lower in the dwarf rats, but significantly increased when these animals were treated with GH. ALP expression was significant higher in the dwarf animals, while it was significantly reduced in the dwarf animals treated with GH.

CONCLUSIONS

The results from this study showed that GH stimulates mitotic activity and delays cartilage cells maturation in the mandibular condyle. This effect at the cellular level may produce changes in the cartilage thickness.

Orthodontic treatment with growth hormone therapy in a girl of short stature

The purpose of this article is to review the characteristics of craniofacial morphology in children of short stature and the effects of human growth hormone (HGH) therapy on the craniofacial complex. Changes in body height, facial growth, and dental maturity of a 9-year-old girl who received HGH therapy during orthodontic treatment were observed. Orthodontists need to understand the skeletal characteristics of the craniofacial complex of short-stature patients before beginning orthodontic treatment and consider how the differences between chronologic and skeletal ages affect the timing and method of orthodontic treatment. If short-stature children are undergoing HGH therapy, its cranioskeletal effect should be considered; if possible, it is better to delay orthodontic treatment until HGH is finished. However, if orthodontic treatment is performed, the following should be considered: (1) HGH therapy affects the growth of the mandible more than the growth of the maxilla, (2) the amount and pattern of growth during HGH administration are unpredictable, and (3) HGH therapy rarely affects dental maturity.

Absolute and relative growth of the rat craniofacial skeleton

Growth of the craniofacial region involves a mosaic of intramembranous and endochondral growth sites that grow at varying rates and mature at different times.

OBJECTIVE

The goal of this study was to compare absolute and relative growth of the craniofacial skeleton in wild-type Lewis rats to measures of somatic growth.

DESIGN

Lateral and dorsoventral X-rays of the head as well as the hindlimb were obtained weekly from 4 to 9 weeks of age. The X-rays were scanned, digitized, and selected linear distances were measured between points. Multilevel statistical models were used to generate absolute growth curves.

RESULTS

Although most growth curves were linear, several were quadratic (exhibiting a deceleration with age), and one displayed a third-order curve. Considerable variation in relative maturity was evident at the first time interval, ranging from 42% of mature (9 week) size (weight) to 97% of mature size (cranial width). Tibial length and body weight were less mature than most, but not all, craniofacial measures. With one exception (bizygomatic width), width measures were relatively more mature than vertical or depth measures. Vertical measures tended to be among the least mature of the craniofacial dimensions. Among the depth (length) measurements, there was a trend of higher maturity for cranial vault/cranial base measures and lower maturity for facial measures.

CONCLUSIONS

The wide spectrum of relative and absolute growth potentials demonstrated in this study indicate that the rodent craniofacial complex is amenable to testing the hypothesis that a component's response potential is related to its growth potential.

Craniofacial and acral growth responses in growth hormone-deficient children treated with growth hormone

OBJECTIVES

To investigate the effects of growth hormone (GH) therapy on craniofacial growth and body proportions in growth hormone deficient children.

STUDY DESIGN

By using a cross-sectional study design, we investigated GH effects on craniofacial growth with photographic facial morphometrics, head circumference, and hand and foot size in 52 children with GH deficiency (GHD) treated with GH (0.27 mg/kg/wk) for 0.19 to 15.5 years, compared with untreated children with GHD and normal first-degree relatives. To detect disproportion and to correct for stature, age and height age (HA) SD scores were analyzed.

RESULTS

Untreated subjects with GHD had retarded facial height and width (P values=.001) compared with normal controls; small head circumference for age and HA (P=.001); small hands for age (P<.001) that were large for HA (P=.003); and small feet for age (P<.001) that were normal for HA. When compared with normal controls, GH-treated subjects had proportional facial heights but narrower facial widths. Head circumference, however, increased disproportionately to height (P=.001), becoming large for stature, and increasing with duration of therapy and cumulative GH dose (P<.001). Hands and feet grew proportionately to height.

CONCLUSION

Growth hormone treatment with conventional doses partially corrects craniofacial deficits and does not adversely affect hand and foot growth but appears to result in excessive head circumference growth.

Craniofacial growth in growth hormone-deficient rats

Although supplementation with growth hormone (GH) is an accepted treatment for children who are GH-deficient or very small in stature, its effect on the craniofacial skeleton has been little studied. The goal of this study was to compare the absolute and relative growth of the craniofacial skeleton in GH-deficient dwarf rats to that in wild-type rats of the same strain, using a mixed-longitudinal radiographic design. Lateral and dorsoventral X-rays of the head and hindlimb were obtained weekly in dwarf and wild-type female Lewis rats from 4 to 9 weeks of age (n = 14 for each time interval). The X-rays were scanned, 27 cephalometric points were digitized, and selected linear distances were measured between points. Multilevel statistical procedures were used to model growth changes in different regions of the head. Among craniofacial measures, growth curves of the two groups differed greatly in the magnitude of initial size differences and the effect of GH deficiency on growth velocity. Considerable variation (65-97%) also existed among craniofacial measures with regard to relative maturity (i.e., the percentage of growth completed between the first and last time intervals). The deficiency effect (a quantitative estimate of the extent to which growth velocity was affected by GH) was negatively correlated (r = -0.52, P < 0.01) with relative maturity of a particular measure. The dependence of the GH effect on relative maturity suggests that different craniofacial morphologies may result depending on the timing of GH supplementation therapy.

Craniofacial morphology and dental age in children with Silver-Russell syndrome

OBJECTIVES

This investigation is a part of a multidisciplinary descriptive evaluation of the Silver-Russell syndrome (SRS). The aim of this study was to describe the craniofacial morphology, occlusion and dental age in children with the SRS.

DESIGN

A descriptive literature-controlled study.

SETTING AND SAMPLE POPULATION

Sixteen children diagnosed as having SRS, 10 boys and six girls, aged 4.4-14.5 years, were referred from different parts of Sweden to the Queen Silvia Children's Hospital, Göteborg University.

EXPERIMENTAL VARIABLE

Facial morphology was measured on lateral and postero-anterior radiographs. Occlusion, tooth eruption and palatal height were measured on casts, and dental maturity was evaluated on orthopantomograms.

OUTCOME MEASURE

Linear and angular measurements were obtained from lateral radiographs and the ratios of the linear measurements from the postero-anterior radiographs. The degree of tooth calcification shown on orthopantomograms was taken as a measure of dental maturity. Biometric measurements were taken and the degree of tooth eruption was recorded from the dental casts. The SRS children were compared with reference groups with t-test and z-scores.

RESULTS

Overall, SRS children were found to have smaller linear facial dimensions and deviations in the facial proportions, such as a small retropositioned, and steeply inclined maxilla and mandible, and a proportionally larger anterior facial height in relation to the posterior facial height. In 40% of them a smaller facial height or length on one side (facial asymmetry) was correlated to the smaller side of the body. The frequency of malocclusions was higher, and the palatal height showed a tendency towards an increase. Dental maturity was within normal limits, while the time of tooth eruption was slightly delayed.

CONCLUSIONS

The deviating facial morphology described above is a part of the syndrome, which is characterized by short stature, growth hormone deficiency and asymmetries of the body. The higher percentage of malocclusions in the SRS children might lead to a greater need of orthodontic treatment.

Craniofacial morphology in obese adolescents

Overweight and obesity are growing problems in the world today. A recent survey shows that about 30% of the adolescent and adult Swedish population is overweight or obese. The etiology is a combination of many factors, the most important of which are physical inactivity and high caloric diet. Obese children have a normal to accelerated growth rate despite low growth hormone (GH) levels. The aim of our study was to investigate whether craniofacial morphology differs between obese adolescents and normal weight adolescents. Lateral cephalograms from 39 adolescents with obesity, aged 14-16 years, were analysed and compared with lateral cephalograms from an equal number of sex- and aged-matched controls. Compared to the controls, the subjects in the obesity group showed increased mandibular length, prognathic jaws and a reduced upper anterior face height. Despite low GH levels, obese children have normal levels of insulin-like growth factor (IGF-1). Since we found an advanced craniofacial growth in obese adolescents with low GH and high IGF-1 serum levels, craniofacial growth may be more dependent on free circulating LGF-1 than on the locally produced portion.

A histological study of the effect of growth hormone on odontogenesis in the Lewis dwarf rat

The effect of growth hormone (GH) on the dentition has been described in children with pituitary dwarfism where teeth fail to form; those that do form tend to be reduced in size and the eruption potential is diminished. The aim here was to examine the effect of GH on odontogenesis via molar development in Lewis (control), dwarf (Dw) and Dw GH-treated (Dw+GH) rats aged 3, 6, 9, 12 and 15 days. Dw+GH animals received a twice-daily dose (65 microg/kg) of GH which commenced at 2 days of age. Animals were killed, mandibles removed, processed to embedding in paraffin, sectioned and stained for histological examination of molar morphology during development. Variations in enamel mineralization and root development were observed. In 6-day-old animals, enamel mineralization was delayed in Dw and Dw+GH animals. Root initiation was evident at 6 days of age in controls but was not observed until 9 days of age in Dw and Dw+GH animals. At 12 days of age, maturation of enamel in Dw and Dw+GH animals remained delayed. By 15 days of age no variation in tooth development was evident. These data indicate that enamel mineralization is affected by the level of circulating GH in the rat. A specific deficiency of GH did not appear to delay bone resorption prior to tooth emergence.

Growth hormone treatment of short children born small for gestational age

Short children born small-for-gestational-age (SGA) appear to be at an increased risk of having a poly-endocrinopathy, including a degree of growth hormone (GH) deficiency and/or insulin-like growth factor 1 (IGF-1) resistance. Among GH-deficient children, those born SGA present a lower growth response to GH therapy than those not born SGA. The growth response of short SGA children to GH treatment does not appear to depend significantly on the secretory status of GH (as judged by provocative testing), indicating that the SGA condition (IGF-1 resistance) predominates over the availability of endogenous GH in determining the short stature of the majority of these children. When a higher than replacement dose of GH is administered, the growth response of short SGA children matches that of GH-deficient non-SGA children, indicating that the IGF-1 resistance towards growth can be overcome, and that a normal stature can be obtained, at least throughout childhood. It is anticipated that, increasingly, the indications and the doses for GH therapy in children will become interlinked with the emerging principles of endocrine programming in early life.