Using zebrafish to investigate cypriniform evolutionary novelties: functional development and evolutionary diversification of the kinethmoid

Although the zebrafish has become a popular model organism for biomedical studies, we propose that the wealth of morphological novelties that characterize this cypriniform fish makes it well suited for investigating the development of evolutionary innovations. Morphological novelties associated with feeding in cypriniform fishes include: a unique structure of the pharyngeal jaws in which the lower pharyngeal jaws are enlarged and opposed to a pad on the basioccipital process; a palatal organ found on the roof of the buccal chamber that is thought to help process detrital food within the buccal chamber; and, the kinethmoid, a novel ossification that effects a unique means of premaxillary protrusion. We present new morphological and developmental data and review functional data regarding the role of the kinethmoid in premaxillary protrusion in the zebrafish. Premaxillary protrusion plays an important role in effective prey acquisition in teleosts and the evolution of a unique means of premaxillary protrusion within Cypriniformes may have led to a number of trophic radiations within this clade. Ontogenetic data from zebrafish show that substantial premaxillary protrusion is not seen until these fish have undergone metamorphosis at which point the adductor mandibulae musculature becomes divided and all ligamentous attachments become established. A comparative study of families within Cypriniformes shows diverse morphologies of the kinethmoid. The morphological diversification that characterizes the kinethmoid suggests that this feeding structure has played a role in trophic radiations within Cypriniformes, since the morphology of this feature is correlated with feeding habits.

An in vitro model of radiation-induced craniofacial bone growth inhibition

Radiation-induced craniofacial bone growth inhibition is a consequence of therapeutic radiation in the survivors of pediatric head and neck cancer. Previously, the infant rabbit orbitozygomatic complex (OZC) was established as a reliable animal model. The purpose of this study was to develop a cell culture model from the rabbit OZC to study the effects of radiation in the craniofacial skeleton. Infant (7-week-old) New Zealand white rabbits were used in this study. Periostea from both OZC were harvested in sterile conditions, introduced into cell culture by way of sequential digestion, and subcultured at confluence. Cultures were analyzed for cellular proliferation (methylthiazoletetrazolium assay), alkaline phosphatase activity, collagen type I expression, and mineralization. Electron microscopy was performed to reveal the in vitro ultrastructure. Subsequently, rabbits were irradiated with sham or 15 Gy radiation, and cell cultures were developed and analyzed for cell numbers. Cell cultures, grown from OZC periostea, expressed osteoblast-like phenotype, with high alkaline phosphatase activity, collagen type 1 expression, and mineralization in an osteogenic environment. Electron microscopy confirmed the characteristic ultrastructural features of osteogenesis in vitro. Finally, significantly (P < 0.01) fewer cells were obtained from animals treated with 15 Gy radiation compared with those from control animals.A primary cell culture with osteoblast-like cellular phenotype was developed from infant rabbit OZC periosteum. This cell culture system responded to in vivo administered radiation by a significant decrease in cell numbers. This in vitro model will be subsequently used to study the cellular mechanisms of radiation and radioprotection in craniofacial osteoblast-like cells.

Radiation-induced craniofacial bone growth disturbances

Multimodality treatment, including radiotherapy, chemotherapy, and surgery, is required for the management of head and neck cancer in pediatric patients. Despite the modern advances in radiation dosing and targeting techniques, the radiation damage to the growing craniofacial skeleton in children remains a significant clinical problem. The first part of this review summarizes the clinical effects of radiotherapy on craniofacial bone growth in children. Experimental evidence on therapeutic radiation effects on bone growth in in vivo and in vitro models is reviewed. The second part of this review focuses on prevention of radiation-induced craniofacial bone growth inhibition using radioprotective agents.

Facial growth prediction: a comparison of methodologies

INTRODUCTION

The purpose of this study was to compare 3 methodologies that predict facial growth relative to incremental and positional changes over short- and long-term time periods. The 3 prediction systems that were tested and compared were the Ricketts analysis, the Johnston grid analysis, and the Fishman maturational analysis.

METHODS

Serial lateral cephalometric headfilms and hand-wrist films of 50 untreated subjects from the Burlington Growth Center at the University of Toronto, Toronto, Ontario, Canada, were used. The sample was subdivided by skeletal classification and further subdivided by sex. The sample comprised 19 skeletal Class I subjects (10 female, 9 male), 20 Class II subjects (10 female, 10 male), and 11 Class III subjects (6 female, 5 male). Three serial headplates were traced on each subject, and the associated chronologic and maturational ages were noted. The subjects were divided into a young adolescent subgroup approximately 9 years of age (T1), a midadolescent subgroup approximately 13 years of age (T2), and a late adolescent-adult age group approximately 20 years of age (T3). Predictions were made between the time periods. To measure and compare the predicted amounts of downward and forward skeletal growth vs the actual growth values, anatomic landmarks were chosen in the cranial base and on the maxilla and the mandible (Point A and gnathion), and increases between the respective points were measured. A paired t test was applied to each test group for the statistical analysis. Graphic representations were also created in the form of "positional envelopes" that encapsulated the predictive data for each methodology. To evaluate both incremental and positional accuracy, these data envelopes were subsequently related to the true positions of Point A and gnathion.

RESULTS AND CONCLUSIONS

Although not the case in every instance, it was demonstrated that the maturationally oriented Fishman analysis was superior to both the chronologically based Johnston grid and Ricketts analysis for short- and long-term predictions.

Sagittal growth of the facial skeleton of 6-year-old children with a complete unilateral cleft of lip, alveolus and palate treated with two different protocols

OBJECTIVE

The purpose of the study was to compare sagittal growth of the facial skeleton of 6-year-old children treated in two cleft centres with different surgical protocols.

MATERIAL AND METHODS

Each group consisted of 20 consecutive non-syndromic children with complete unilateral cleft lip, alveolus and palate. They all had presurgical orthopaedics with a passive plate and external strapping until lip repair. Centre 1 had lip repair at the age of 3 months and one stage palatal closure at the age of 1 year. Closure of the alveolar cleft was planned at 9 years with bone grafting. In centre 2 lip repair was performed at the age of 6 months, soft palate repair at 12 months and hard palate repair together with mucoperiosteal closure of the alveolar cleft at the age of 30 months. At the time of investigation, the children from both centres had not received any postoperative orthodontic treatment. Sagittal growth was evaluated on lateral cephalograms using the angles SNA, SNB, ANB and SNPg. For control, Droschl standards were used. The Mann-Whitney U test was used for statistical analysis.

RESULTS

There was no statistically significant difference in SNA, SNB, ANB and SNPg between the centres at the age of 6 years. There were no children with a class III jaw relationship. The sagittal dimensions were close to the values of non-cleft control persons (Droschl standards).

CONCLUSION

There was considerable similar sagittal growth of the facial skeleton in both centres which has not been affected by the different surgical protocols so far. A final evaluation should be delayed until the growth of the facial skeleton is complete.

Radioprotection of craniofacial bone growth

In this review, the potential of pharmacologic therapy for prevention of radiation-induced bone growth inhibition is discussed. Significant radioprotection using the radioprotector Amifostine has been achieved in animal models of radiation-induced retardation of long and craniofacial bone growth. Moreover, radioprotection in vitro has been achieved in a number of cell lines, including osteoblast-like, endothelial, and fibroblastic. This evidence may support future clinical investigations of radioprotector Amifostine or similar substances for radioprotection of the growing craniofacial skeleton.

Allometries throughout the late prenatal and early postnatal human craniofacial ontogeny

Craniofacial shape changes throughout the late prenatal and early postnatal ontogeny (32-47 weeks of gestational age) were explored. The purpose was to evaluate whether the skull follows an allometric growth pattern, as was observed in other ontogenetic periods, and to assess shape variation patterns for the cranial vault, cranial base, and face. Thirty three-dimensional landmarks were registered in 54 skulls. Wire-frames were built with landmarks to observe shape variation in the following cranial components: anteroneural, midneural, posteroneural, optic, respiratory, masticatory, and alveolar. The landmark configurations were subjected to generalized Procrustes analyses, and the shape coordinates obtained were subjected to Principal Components Analyses. Multivariate regression of the shape variables (the principal components) on the size vector (the centroid size) was performed to assess allometries. Transformation grids were constructed to identify how cranial components interact across ontogeny. Results indicated that highly significant shape changes depend on size changes. Important shape variation in the vault, small variation in the cranial base, and no variation in the face were observed. Brain growth is proposed to be the major influence on craniofacial shape change, which produces a relative elongation and compression of midneural and posteroneural components. The cranial base elongates by intrinsic factors and affects position of the face. Ontogenetically, the cranial base seems to be independent with respect to brain growth, in contrast to what has been suggested in comparisons at higher taxonomic levels.

Influence of unilateral masseter muscle atrophy on craniofacial morphology in growing rabbits

PURPOSE

The purpose of the study was to evaluate whether the induction of unilateral masticatory muscle dysfunction can alter the skeletal growth patterns.

MATERIALS AND METHODS

Twenty-one white male New Zealand rabbits (4 weeks old) were divided into 3 groups of 7 subjects: group 1 served as the control to study normal craniofacial growth. In groups 2 and 3, rabbits were injected with 5 units and 15 units of Botulinum toxin A (BTXA) into the right masseter muscle, respectively. The effect of a neuromuscular blockade of masseteric activity on craniofacial growth was evaluated with 3 samples of serial computed tomography (CT) scans with a slice thickness of 0.625 mm, taken at 4 weeks (base line), 8 weeks (endpoint of prepubertal craniofacial growth), and 24 weeks (after pubertal growth).

RESULTS

The ipsilateral mandibular ramus height, zygomatic arch length, and masseteric length did not develop as much as those of the contralateral side after pubertal growth. At age 24 weeks, the masseter muscle volume asymmetry index reached -13.8% (group 2), -18.4% (group 3), and -1.6% for the control group. The ipsilateral side of the hemimandible showed less bone volume after 8 weeks but it showed partially recovered symmetry at 24 weeks. The maxillomandibular incisor midline and transverse molar discrepancies were not evident in any of the groups.

CONCLUSIONS

The BTXA injection can be an effective method in inducing site-specific muscular hypofunctions so that masticatory muscle-craniofacial bone interaction can be investigated efficiently. The result showed that the unilateral atrophy of the masseter muscle in the growing subjects influenced the morphology of the local skeletal sites. This did not, however, result ultimately in mandibular midline asymmetry or right-left asymmetry in hemimandibular volume after growth. The results imply that alterations in specific masticatory muscle function can be compensated by the growth of other structural components.

Sagittal craniofacial growth evaluated on children dry skulls using V2 and V3 canal openings as references

The purpose of this study was to investigate the relationship between standard cephalometric landmarks and lines and those using ovale, rotundum, greater palatine and infra-orbital foramina as references. Thirty-four children dry skulls, 19 males and 15 females aged 0-6 years, were examined by computed tomography scanning. The classical cephalometric dimensions of skull base were measured from middle sagittal plane crossing over basion, nasion and sella turcica. Those of hard palate (maxilla and palatine bone) were measured from axial plane intersecting posterior nasal spine and anterior nasal spine. The dimensions between ovale and rotundum foramina, rotundum and infra-orbital foramina, greater palatine and infra-orbital foramina were determined by using constructed tomographic planes enclosing these different foramina. Biostatistical analysis using partial correlations showed that the linear variables with nerve canal openings as references are strongly related to length of both the skull base and of the hard palate. The results highlight the importance of the nerve canal openings of skull base and bone facial components in normal or pathologic craniofacial growth investigations.

Secular trends in the facial skull from the 19th century to the present, analyzed with geometric morphometrics

INTRODUCTION

Over the last 100 years, Austrian facial form has changed for various reasons, including changes in growth pattern, changes in shape pattern, or a combination of these. In this study, we explored and contrasted these 2 explanations.

METHODS

We compared cephalograms from 54 recruits in the present-day Austrian Federal Army to those from 49 dry skulls of soldiers from the Imperial Hapsburg army. Body height was measured or acquired from military records. Forty-three landmarks were located on each lateral cephalogram. Secular change and growth allometry were analyzed with standard Procrustes methods.

RESULTS

Body height correlated only weakly with size of the facial skull in these samples, and secular change in facial size (4.5% over a century) was proportionately less than that in height. Growth allometry was nearly unchanged over the century, emphasizing the typical changes of vertical to horizontal proportions and bimaxillary prognathism. Secular changes over the century took the form of far more localized remodeling around the coronoid process and the anterior maxilla. The large-scale differences, in contrast, were opposite to those one would expect from the size change.

CONCLUSIONS

The observed trends shed considerable light on secular changes in the range of dysmorphologies for clinical orthodontic correction. At the same time, the dissociation between within-century and between-century allometry is an important possibility that was hitherto typically observed only at far greater time scales than the 150 years spanned by these data.

Midface Growth in Patients with Ectrodactyly-Ectodermal Dysplasia-Clefting Syndrome

BACKGROUND

Ectrodactyly-ectodermal dysplasia-clefting syndrome is an autosomal dominant disorder involving abnormalities of the hands, feet, skin, and teeth and clefts of the lip and palate. Patients with this syndrome have abnormal facial features--namely, clefts of the lip and palate--and abnormal dentition, which could affect the growth of their midface region. The purpose of this study was to describe characteristics of midface growth in patients with this syndrome.

METHODS

A retrospective chart review was conducted for eight postoperative patients seen at the cleft clinic at The Children's Hospital of Philadelphia between 1987 and 2004. Clinical notes and operative reports were reviewed. The surgeon's assessment and cephalometric measurements were analyzed. The cephalometric values were compared with Bolton standards for normal facial growth to determine deficiency.

RESULTS

All eight patients displayed midface disproportion. Five of the eight were found to have some degree of midface retrusion. The upper anterior facial height was found to be deficient for half of the patients. Six patients had deficient lower facial height and four had deficient total face height. Two of these patients have undergone midface distraction osteogenesis.

CONCLUSIONS

The authors' study identified a subset of patients within the cleft clinic who carry the diagnosis of ectrodactyly-ectodermal dysplasia-clefting syndrome. The patients tend to have poor dentition that, coupled with clefts of the lip and palate, inhibits normal midface growth and can require surgical correction. The need for orthognathic surgery seems to be greater than that seen in patients who have clefts of the lip and palate but do not carry the syndrome.

Craniofacial levels and the morphological maturation of the human skull

It is well known that the human skull achieves adult size through a superior-inferior gradient of maturation. Because the basicranium matures in size before the face, it has been suggested that the form of the basicranium might have ontogenetic knock-on effects on that of the face. However, although sequential spatially organized maturation of size is well described in the cranium, the maturation of skull shape is not. Knowledge of the maturation of shape is important, nevertheless, because it is claimed that the early determination of the spatial configuration of basicranial components, where the facial skeleton attaches, is relevant in the spatio-temporal ontogenetic cascade from basicranium to face. This paper examines the ontogeny of various components of the human skull in 28 individuals from the longitudinal Denver Growth Study. Sixty-six landmarks and semilandmarks were digitized on 228 X-rays and analysed using geometric morphometric methods. Bootstrapped confidence intervals for centroid size support previous studies suggesting a supero-inferior gradient of growth maturation (size over time), while developmental maturation (shape over time) is more complex. A sequence of shape maturation is described, in which the earliest structure to mature in shape was the midline cranial base (7-8 years), followed by the lateral cranial floor (11-12), midline neurocranium (9-10) and facial and mandibular structures (15-16). The absolute ages of shape maturation of the latter three depended on the criterion of maturity used, which was not the case for the basicranial components. Additionally, ontogenetic dissociations were found between the maturation of size and shape of the midline cranial base and lateral floor, possibly underlining its role as structural 'interface' between brain and facial ontogeny. These findings imply potential for bidirectional developmental influences between the lateral cranial floor and the face until about 11-12 years. The findings are discussed with regard to their relevance for palaeoanthropology and especially the evolutionary and developmental bases of skull morphological variation.

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.

Facial ontogeny in Neanderthals and modern humans

One hundred and fifty years after the discovery of Neanderthals, it is held that this morphologically and genetically distinct human species does not differ from modern Homo sapiens in its craniofacial ontogenetic trajectory after the early post-natal period. This is striking given the evident morphological differences between these species, since it implies that all of the major differences are established by the early post-natal period and carried into adulthood through identical trajectories, despite the extent to which mechanical and spatial factors are thought to influence craniofacial ontogeny. Here, we present statistical and morphological analyses demonstrating that the spatio-temporal processes responsible for craniofacial ontogenetic transformations differ. The findings emphasize that pre-natal as well as post-natal ontogeny are both important in establishing the cranial morphological differences between adult Neanderthals and modern humans.

Longitudinal intermaxillary relationships in class III malocclusions with low and high mandibular plane angles

OBJECTIVE

To analyze the sagittal, vertical, and transverse relationships of the maxilla and mandible in Japanese girls with Class III malocclusions with different inclination of mandibular plane.

MATERIALS AND METHODS

This longitudinal study utilized serial posteroanterior and lateral cephalograms of 56 untreated subjects from the age of 8 years until the age of 14 years (low mandibular plane angle group: n = 20; average mandibular plane angle group: n = 15; high mandibular plane angle group: n = 21). Sagittal and vertical growth was analyzed on the basis of lateral cephalograms, and transverse growth was analyzed on the basis of posteroanterior cephalograms.

RESULTS

There was no significant difference in intermaxillary sagittal relationships among the three groups from age 8 until 14. On the other hand, there were significant changes in the vertical and transverse intermaxillary relationships during this period. When comparing the three groups at the same age, there were significant differences in vertical and transverse intermaxillary relationships in some ages, whereas no significant difference was found in sagittal relationships in any ages.

CONCLUSIONS

The inclination of mandibular plane might play a role in anticipating changes in vertical and transverse intermaxillary relationships from 8 until 14 years of age.

Gene discovery in craniofacial development and disease--cashing in your chips

An unbiased, polygenic approach is needed to unravel the complex molecular bases of craniofacial development and disease. DNA microarrays, the current paradigm of genome-wide analysis, permit the simultaneous study of many thousands of genes, the ready identification of candidate molecules and pathways, and the compilation of gene expression profiles for whole systems--pathologic and embryonic alike. We survey the existing literature applying microarrays to craniofacial biology and highlight the value of animal models, particularly mice and chickens, to understanding molecular regulation in the craniofacial complex. We also emphasize the importance of functional studies and high-throughput assays to extracting useful data from microarray output. It is our goal to help put researchers and clinicians on the same page as microarray technology moves into the forefront of craniofacial biology.

Effects of activator and high-pull headgear combination therapy: skeletal, dentoalveolar, and soft tissue profile changes

The aim of this study was to evaluate skeletal, dentoalveolar, and soft tissue profile changes with activator and high-pull headgear combination therapy in patients with Class II malocclusions caused by maxillary prognathism and mandibular retrognathism. The subjects, all in the mixed dentition, were selected from a single centre and were divided into two groups: 28 patients were treated with an incisor double capping activator and a high-pull headgear combination appliance (13 girls, 15 boys mean chronological age 11.7 +/- 1.2 years, skeletal age 12.1 +/- 1.4 years) and an untreated group of 28 subjects (14 girls, 14 boys mean chronological mean age 11.9 +/- 1.1 years, skeletal age 12.3 +/- 1.3 years). The skeletal, dentoalveolar, and soft tissue profile changes that occurred were compared on lateral cephalograms taken before treatment (T0) and after 1.1 +/- 0.3 years when the combination appliance was removed (T1). In the control group, the radiographs were obtained at the start (T0) and after an observation period 1.2 +/- 0.4 years (T1). Statistical analysis was undertaken with Wilcoxon's ranked-sum test for intra-group comparisons and differences between groups with t-test and Bonferroni's test at a level of significance of P < 0.05. Activator and high-pull headgear combination treatment in these growing patients resulted in a correction of the skeletal Class II relationship (ANB -3.4 degrees), a restriction of maxillary growth (SNA -2.0 degrees, OLp-A -2.3 mm), an advancement of the mandibular structures (SNB +2.6 degrees, FH-NPg +2.3 degrees, OLp-B +2.7 mm, OLp-Pg +2.2 mm), an increase in lower face height (ANS-Me +3.9 mm), a correction of the overjet (-5.4 mm), an improvement in overbite (-2.2 mm), uprighting of the maxillary incisors (U1-FH -5.3 degrees, OLp-U1 -2.5 mm), protrusion of the mandibular incisors (IMPA +2.0 degrees, OLp-L1 +2.7 mm), and a correction of the dental Class II malocclusion (OLp-L6 +3.5 mm). The soft tissue profile changes were a correction of facial convexity (G'-Sn-Pg' angle 2.3 degrees, Mlf-Li-x-axis angle 9.1 degrees), and an increase in lower antero-posterior (Mlf-y-axis 5.6 mm, Pg'-y-axis 5.3 mm), and lower vertical (Sls-x-axis 3.8 mm, Pg'-x-axis 3.8 mm, Me'-x-axis 5.1 mm) soft tissue dimensions. The mentolabial fold depth (Mlf-E line) also significantly decreased, -0.8 mm in the treated group. The activator and high-pull headgear combination appliance was effective in treating growing patients with maxillary prognathism, mandibular deficiency, and facial convexity by a combination of skeletal and dentoalveolar changes and improvement in the soft tissue facial profile.

Craniofacial growth and functional change in oligodontia with ectodermal dysplasia: a case report

A case of ectodermal dysplasia in a Japanese boy is presented in this report. After prosthetic treatment was performed with partial dentures in both jaws, mandibular movement, dental casts, and lateral and frontal cephalograms were taken at an initial visit (age 7 years 8 months), and at follow-up 1 year and 8 months later (age 9 years 3 months) to evaluate the developmental changes in masticatory movement, dental arch width, and craniofacial morphology. Stability of the jaw movements improved during the follow-up period both with and without dentures. The facial skeleton grew between the initial visit and follow-up. Mandibular length remained long compared with the average value for Japanese children. A possible genetic marker for mandibular growth (growth hormone receptor), which is considered to be an important factor in mandibular growth and development, was analysed for the gene variant and the result supported the characteristic mandibular growth in the reported case. These results indicate the characteristic craniofacial growth in this disease and emphasize the potential ability of functional development of jaw movements with oligodontia.

Skeletal and Dental Changes in Class II division 1 Malocclusions Treated with Splint-Type Herbst Appliances

OBJECTIVE

To evaluate skeletal and dental changes in growing individuals through lateral cephalograms obtained after the sole use of the splint-type Herbst appliances in Class II division 1 malocclusions.

METHODS

Several electronic databases (Pubmed, Medline, Medline In-Process & Other Non-Indexed Citations, Cochrane Library Database, Embase, Web of Sciences, Scopus, and Lilacs) were searched with the help of a health sciences librarian. Abstracts that appeared to fulfill the initial selection criteria were selected by consensus. The original articles were then retrieved. Their references were also hand-searched for possible missing articles. Clinical trials that assessed, through lateral cephalograms, immediate skeletal and dental changes with the use of splint-type Herbst appliances without any concurrent orthodontic appliances, surgical intervention, or syndromic characteristics were considered. A comparable untreated Class II division 1 malocclusion control group was required to factor out normal growth changes.

RESULTS

Three articles were finally selected and analyzed. An individual analysis of these articles was made and some methodological flaws were identified. The selected studies all showed statistically significant changes in the anteroposterior length of the mandible, vertical height of the ramus, lower facial height, mandibular incisor proclination, mesial movement of the lower molars, and distal movement of the upper molars. Posttreatment relapse in overjet and molar relationship was also observed.

CONCLUSIONS

Dental changes are as important as skeletal changes to attaining the final occlusal results. Long-term, prospective, double-blinded, randomized clinical trials are needed to support these conclusions.

Hard palate repair timing and facial growth in cleft lip and palate: a systematic review

OBJECTIVE

To evaluate the effect of timing of hard palate repair on facial growth in patients with cleft lip and palate, with special reference to cranial base, maxilla, mandible, jaw relation, and incisor relation.

DESIGN

A systematic review.

METHODS

The search strategy was based on the key words "facial growth," "cleft lip palate," and "timing of (hard) palate repair." Case reports, case-series, and studies with no control or comparison group in the sample were excluded.

RESULTS

Fifteen studies met the selection criteria. All the studies were retrospective and nonrandomized. Five studies used cephalometry and casts, seven used cephalometry, and three used casts. Methodological deficiencies and heterogeneity of the studies prevented major conclusions.

CONCLUSION

The review highlights the importance of further research. Prospective well-designed, controlled studies, especially targeting long-term results, are required to elucidate the effect of timing of hard palate repair on facial growth in patients with cleft lip and palate.

Hard palate repair timing and facial growth in unilateral cleft lip and palate: a longitudinal study

OBJECTIVE

To investigate whether timing of hard palate repair had a significant effect on facial growth in patients with unilateral cleft lip and palate (UCLP).

DESIGN

Retrospective longitudinal study.

SETTING

Sri Lankan Cleft Lip and Palate Project.

PATIENTS

A total of 104 patients with nonsyndromic UCLP who had hard palate repair by age 13 years, with their 290 cephalometric radiographs taken after lip and palate repair.

MAIN OUTCOME MEASURES

Clinical notes were used to record surgical treatment histories. Cephalometry was used to determine facial morphology and growth rate.

RESULTS

Timing of hard palate repair had a significant effect on the length and protrusion of the alveolar maxilla (PMP-A and SNA, respectively) and the anteroposterior alveolar jaw relation (ANB) at age 20 years but not on their growth rates.

CONCLUSION

Timing of hard palate repair significantly affects the growth of the maxilla in patients with UCLP. Late hard palate repair has a smaller adverse effect than does early hard palate repair on the growth of the maxilla. This timing effect primarily affects the anteroposterior development of the maxillary dentoalveolus and is attributed to the development being undisturbed before closure of the hard palate.

Dental maturation in short and long facial types. Is there a difference?

OBJECTIVE

The purpose of this investigation was to study the relationship between vertical skeletal growth pattern and dental maturation in children with long or short anterior facial height.

MATERIALS AND METHODS

The sample consisted of the records of 312 Dutch children (153 boys and 159 girls, aged 9-12.9 years, with a mean chronological age of 11.3 years). The subjects were selected according to their lower anterior facial height as a percentage of the total facial height. Two groups, one with long and the other with short anterior facial height, were formed for further comparison. Dental age, according to Demirjian's dental maturity score, was determined for each subject. The power of the study was 79% (2-sided test) and 87% (1-sided test).

RESULTS

There was no statistically significant difference in dental age score between the two extreme groups. The subjects with short anterior facial height demonstrated a slight tendency toward more advanced dental age.

CONCLUSIONS

The difference in dental age between long and short facial types is not big enough to be clinically relevant.

Contribution of mGluR and Fmr1 functional pathways to neurite morphogenesis, craniofacial development and fragile X syndrome

Fragile X Syndrome is a leading heritable cause of mental retardation that results from the loss of FMR1 gene function. Studies in mouse and Drosophila model organisms have been critical in understanding many aspects of the loss of function of the FMR1 gene in the human syndrome. Here, we establish that the zebrafish is a useful model organism for the study of the human fragile X syndrome and can be used to examine phenotypes that are difficult or inaccessible to observation in other model organisms. Using morpholino knockdown of the fmr1 gene, we observed abnormal axonal branching of Rohon-Beard and trigeminal ganglion neurons and guidance and defasciculation defects in the lateral longitudinal fasciculus. We demonstrate that this axonal branching defect can be rescued by treatment with MPEP [2-methyl-6-(phenylethynyl) pyridine]. This is consistent with an interaction between mGluR signalling and fmr1 function in neurite morphogenesis. We also describe novel findings of abnormalities in the abundance of trigeminal ganglion neurons and of craniofacial abnormalities apparently due to dysmorphic cartilage formation. These abnormalities may be related to a role for fmr1 in neural crest cell specification and possibly in migration.

Life-long protein malnutrition in the rat (Rattus norvegicus) results in altered patterns of craniofacial growth and smaller individuals

Dietary protein is a limiting factor in mammalian growth, significantly affecting the non-linear trajectories of skeletal growth. Young females may be particularly vulnerable to protein malnutrition if the restriction is not lifted before they become reproductive. With such early malnutrition, limited amino acids would be partitioned between two physiological objectives, successful reproduction vs. continued growth. Thus, the consequences of protein malnutrition could affect more than one generation. However, few studies have quantified these cross-generational effects. Our objective was to test for differences in skeletal growth in a second generation of malnourished rats compared with rats malnourished only post-weaning, the first generation and with controls. In this longitudinal study we modelled the growth of 22 craniofacial measurements with the logistic Gompertz equation, and tested for differences in the equation's parameters among the diet groups. The female offspring of post-weaning malnourished dams did not catch up in size to the first generation or to controls, although certain aspects of their craniofacial skeleton were less affected than others. The second generation's growth trajectories resembled the longer and slower growth of the first malnourished generation. There was a complex interaction between developmental processes and early nutritional environment, which affected variation of adult size.

Morphometric analysis of the effects of LactoSorb bioabsorbable plates on the craniofacial growth of rabbits using computed tomography

This study investigated the effect of bioabsorbable plates and titanium microscrews on the growth of the craniofacial skeleton of rabbits (Oryctolagus cuniculus) in the neonatal period. All animals underwent surgery at seven weeks of age and were killed at twenty-four weeks. In the study group, LactoSorb plate and PROMM titanium microscrews were positioned across the coronal suture. In the control group, only PROMM titanium microscrews were attached to the cranium. Computed tomography was used to obtain morphometric measurements of volume. Results showed no significant intergroup (P < or = 0.05) or intragroup (control group P < or = 0.01; study group P < or = 0.05) differences in craniofacial volume. Under the experimental conditions of this study, bioabsorbable plates did not affect neonatal growth of craniofacial volume in rabbits.