The primary role of functional matrices in facial growth

The Developmental Basis of Quantitative Craniofacial Variation in Humans and Mice

The human skull is a complex and highly integrated structure that has long held the fascination of anthropologists and evolutionary biologists. Recent studies of the genetics of craniofacial variation reveal a very complex and multifactorial picture. These findings contrast with older ideas that posit much simpler developmental bases for variation in cranial morphology such as the growth of the brain or the growth of the chondrocranium relative to the dermatocranium. Such processes have been shown to have major effects on cranial morphology in mice. It is not known, however, whether they are relevant to explaining normal phenotypic variation in humans. To answer this question, we obtained vectors of shape change from mutant mouse models in which the developmental basis for the craniofacial phenotype is known to varying degrees, and compared these to a homologous dataset constructed from human crania obtained from a single population with a known genealogy. Our results show that the shape vectors associated with perturbations to chondrocranial growth, brain growth, and body size in mice do largely correspond to axes of covariation in humans. This finding supports the view that the developmental basis for craniofacial variation funnels down to a relatively small number of key developmental processes that are similar across mice and humans. Understanding these processes and how they influence craniofacial shape provides fundamental insights into the developmental basis for evolutionary change in the human skull as well as the developmental-genetic basis for normal phenotypic variation in craniofacial form.

The influence of sucking habits on occlusion development in the first 36 months

OBJECTIVE: The objective of this study was to identify the influence of sucking habits on the occlusal characteristics of the deciduous dentition. METHODS: The initial sample consisted of 86 infants, aged 0 to 3 months. Seven home visits were performed, when and information on breastfeeding practice, nutritive and non-nutritive sucking habits, mouth breathing and dentition development was collected. From the first sample, impressions of the dental arches were obtained from 58 children at the age of 36 months (+2.51SD). Dental casts were obtained and two examiners, trained and calibrated by the Kappa and Pearson Correlation tests, measured several parameters of dental occlusion, such as arch length, depth, and width. RESULTS: The results showed that bottle feeding before 6 months was associated to an increased mandibular intermolar width (p=0.01). Pacifier use before 6 months was statistically associated to a reduction of the maxillary intercanine (p=0.03) and intermolar (p=0.03) width. In addition to these findings, the increased molar depth of the maxillary arch was associated to loss of lip closure before the age of 12 months (p= 0.03). CONCLUSION: According to these results, it could be concluded that sucking habits interfere with the determination of some deciduous occlusal characteristics: pacifier sucking limits lateral-lateral maxillary growth, bottle feeding favors lateral-lateral mandibular growth and open bite development, and the lack of lip closure favors the anteroposterior maxillary growth.

On Bernard Sarnat's 100th birthday: pathology and management of craniosynostosis

The focus on nonsyndromic craniosynostosis, the most common type of isolated craniosynostosis, is sagittal, followed by unilateral coronal, bilateral coronal, metopic, and lambdoid, in order of decreasing frequency. Certain forms of craniosynostosis display a sex predilection. For example, boys outnumber girls in a 4:1 ratio in sagittal synostosis, but girls outnumber boys in a 3:2 ratio in unilateral coronal synostosis. Other forms, such as metopic, lambdoid, and bilateral coronal synostosis, demonstrate no sex dominances tract.

Measures of growth in children at risk for Huntington disease

OBJECTIVE

The effect of mHTT on human development was examined by evaluating measures of growth in children at risk for Huntington disease (HD).

METHODS

Children at risk for HD with no manifest symptoms (no juvenile HD included) were enrolled and tested for gene expansion for research purposes only. Measurements of growth (height, weight, body mass index [BMI], and head circumference) in children tested as gene-expanded (n = 20, 7-18 years of age, CAG repeats ≥39) were compared to those of a large database of healthy children (n = 152, 7-18 years of age).

RESULTS

Gene-expanded children had significantly lower measures of head circumference, weight, and BMI. Head circumference was abnormally low even after correcting for height, suggesting a specific deficit in brain growth, rather than a global growth abnormality.

CONCLUSIONS

These results indicate that, compared to a control population, children who were estimated to be decades from HD diagnosis have significant differences in growth. Further, they suggest that mHTT may play a role in atypical somatic, and in particular, brain development.

It takes a mouth to eat and a nose to breathe: abnormal oral respiration affects neonates' oral competence and systemic adaptation

Mammalian, including human, neonates are considered to be obligate nose breathers. When constrained to breathe through their mouth in response to obstructed or closed nasal passages, the effects are pervasive and profound, and sometimes last into adulthood. The present paper briefly surveys neonates' and infants' responses to this atypical mobilisation of the mouth for breathing and focuses on comparisons between human newborns and infants and the neonatal rat model. We present the effects of forced oral breathing on neonatal rats induced by experimental nasal obstruction. We assessed the multilevel consequences on physiological, structural, and behavioural variables, both during and after the obstruction episode. The effects of the compensatory mobilisation of oral resources for breathing are discussed in the light of the adaptive development of oromotor functions.

Nasal septal and craniofacial form in European- and African-derived populations

As a component of the chondrocranium, the nasal septum influences the anteroposterior dimensions of the facial skeleton. The role of the septum as a facial growth center, however, has been studied primarily in long-snouted mammals, and its precise influence on human facial growth is not as well understood. Whereas the nasal septum may be important in the anterior growth of the human facial skeleton early in ontogeny, the high incidence of nasal septal deviation in humans suggests the septum's influence on human facial length is limited to the early phases of facial growth. Nevertheless, the nasal septum follows a growth trajectory similar to the facial skeleton and, as such, its prolonged period of growth may influence other aspects of facial development. Using computed tomography scans of living human subjects (n = 70), the goal of the present study is to assess the morphological relationship between the nasal septum and facial skeleton in European- and African-derived populations, which have been shown to exhibit early developmental differences in the nasal septal-premaxillary complex. First we assessed whether there is population variation in the size of the nasal septum in European- and African-derived samples. This included an evaluation of septal deviation and the spatial constraints that influence variation in this condition. Next, we assessed the relationship between nasal septal size and craniofacial shape using multivariate regression techniques. Our results indicate that there is significant population variation in septal size and magnitude of septal deviation, both of which are greater in the European-derived sample. While septal deviation suggests a disjunction between the nasal septum and other components of the facial skeleton, we nevertheless found a significant relationship between the size of the nasal septum and craniofacial shape, which appears to largely be a response to the need to accommodate variation in nasal septal size.

New insights on age-related association between nasopharyngeal airway clearance and facial morphology

OBJECTIVES

To evaluate the relation between adenoid hypertrophy and facial morphology across age in a pediatric population.

SETTING AND SAMPLE POPULATION

The American University of Beirut Department of Otolaryngology. Two-hundred consecutive children (age 6.00 ± 2.62 years) referred from the Pediatric Otolaryngology unit to the Orthodontic division and requiring a lateral cephalogram for adenoid hypertrophy assessment.

METHODS

Cephalometric measurements included relations among cranial base, maxilla and mandible, and airway clearance measured from adenoid to soft palate (AD). The children were classified into two age groups, Group 1: ≤ 6 years (n = 124) and Group 2: ≥ 6.01 years (n = 76), and also stratified in four subgroups (A, B, C, D) based on maxillo-mandibular divergence (palatal to mandibular plane angle, PP-MP): A- PP-MP ≤ 27.5°, n = 34; B- 27.5° < PP-MP ≤ 32°, n = 68; C- 32°<PP/MP<36.5°, n = 67; D- PP-MP ≥ 36.5°, n = 31. Statistics included t-tests and anova for group differences.

RESULTS

  Differences between groups 1 and 2 were statistically significant (p < 0.05) for AD (Group 1: 3.19 ± 2.32 mm, Group 2: 4.78 ± 2.80 mm), ANB (5.38 ± 2.24°, 4.38 ± 2.54°), LFH (56.61 ± 1.95%, 55.38 ± 1.84%), PP-H (-8.41 ± 3.28°, -6.49 ± 3.46°), and overbite (0.55 ± 2.00 mm, 1.16 ± 2.36 mm). Among subgroups, statistically significant differences (p < 0.05) occurred mainly between the most hyperdivergent group (D) and the hypodivergent (A) and normodivergent (B) groups.

CONCLUSIONS

Airway measurements were smallest in children ≤ 6 years and those presenting severe hyperdivergent pattern, which denoted the most severe airway obstruction. The findings suggest airway clearance before age 6 in the most severely affected children, but follow-up research on actual adenoidectomies in younger children is needed to determine guidelines.

Current concepts in pediatric temporomandibular joint disorders: Part 1. Etiology, epidemiology, and classification

BACKGROUND

Pediatric temporomandibular joint dysfunction, resulting from either soft-tissue or skeletal disorders, may be congenital or acquired. Congenital temporomandibular joint disorders are uncommon. The authors review their experience with pediatric temporomandibular joint disorders and propose a new classification system.

METHODS

Clinical records, cephalograms, computed tomographic scans, magnetic resonance images, and pathologic specimens of all pediatric patients (younger than 18 years) with trismus or restricted mandibular excursion from 1976 to 2008 were reviewed. Cases were stratified according to soft-tissue or skeletal pathologic findings; skeletal abnormalities were further characterized as intracapsular or extracapsular.

RESULTS

Thirty-eight patients, ranging in age from 1 day to 18 years at diagnosis, were identified with temporomandibular joint disorders. Ten cases (26.3 percent) were attributable to soft-tissue abnormality. The remaining 28 cases (73.7 percent) were attributable to skeletal abnormality, consisting of 14 congenital and 14 acquired cases (50 percent each). Acquired skeletal deformities included 12 intracapsular ankyloses (85.7 percent) and two extracapsular ankylosis (14.3 percent) (extraarticular bone blocks). Congenital skeletal deformities accounted for five intracapsular ankyloses (35.7 percent) and nine extracapsular ankyloses (64.3 percent).

CONCLUSIONS

On initial survey, the data are consistent with published reports that attribute temporomandibular joint dysfunction to acquired abnormality (i.e., trauma and infection). However, the authors observed a significantly higher percentage (50 percent) of congenital temporomandibular joint skeletal disorders than previously reported. Most congenital cases involved extracapsular abnormality (i.e., coronoid hypertrophy); only a minority of cases had glenoid-condylar fibro-osseous fusion (i.e., intracapsular ankyloses). Because the diagnosis and classification of temporomandibular joint disorders determine treatment options, the authors provide a new classification that characterizes the extent of capsular involvement.

Nasal cavity size, airway resistance, and subjective sensation after surgically assisted rapid maxillary expansion: a prospective longitudinal study

INTRODUCTION

The aims of this study were to measure changes in nasal minimum cross-sectional area and nasal airway resistance after surgically assisted rapid maxillary expansion and to explore a possible correlation with the subjective sensation of nasal obstruction.

METHODS

Minimum cross-sectional area and nasal airway resistance were measured in 39 consecutive patients treated with surgically assisted rapid maxillary expansion. Subjective nasal obstruction was assessed by a questionnaire at pretreatment and at 3 and 18 months postoperatively.

RESULTS

Subjective nasal obstruction had improved significantly by 3 months postoperatively. Minimum cross-sectional area increased and nasal airway resistance decreased. No correlations were found. In subjects with pretreatment subjective nasal obstruction and initially narrow anterior minimum cross-sectional area, there was a significant correlation between a moderate increase in anterior minimum cross-sectional area and improvement in perceived nasal obstruction. Eighteen months postoperatively, no changes were found from pretreatment values for subjective nasal obstruction, minimal cross-sectional area, or nasal airway resistance, and there were no correlations. Subjects with a sensation of nasal obstruction at treatment start reported a lasting significant subjective improvement.

CONCLUSIONS

The postoperative effects of surgically assisted rapid maxillary expansion did not persist in the long term. No correlation was found between objective and subjective findings. Subjects with pretreatment nasal obstruction, however, reported a lasting sensation of improved nasal function after surgically assisted rapid maxillary expansion.

Effects of hypodontia on craniofacial structures and mandibular growth pattern

Introduction

This study was performed to examine craniofacial structures in persons with hypodontia and to reveal any differences, that may occur, when agenetic teeth are only found in the maxilla, the mandible or in both jaws. The groups consistent of 50 children (33 girls, 17 boys) aged between 9 and 13.5 years were analyzed and assigned to three subgroups. Group 1 = upper jaw hypodontia. Group 2 = lower jaw hypodontia. Group 3 = hypodontia in both jaws.

Materials and methods

Eleven angular and three index measurements from lateral encephalographs and two linear measurements from dental blaster casts were calculated. All data was statistically analyzed, parameters with p < 5% were investigated for each subgroup respectively.

Results

In comparison with standards the study group showed bimaxillary retrognathism and a reduction of the lower anterior facial height. Moreover both overbite and overjet significantly increased. Other values laid within the normal ranges. Evaluating results of the subgroups, differences in the means of SNA, SNB and overjet between the groups were observed.

Analysis of the mandibular growth pattern revealed, that neither vertical nor horizontal patterns are dominant in hypodontia patients.

Conclusions

In certain dentofacial parameters differences between persons with hypodontia and such with full dentition exist. According to our findings agenetic teeth may have a negative influence on the saggital development of a jaw and the lower face and may be responsible for increased overbites. This should receive attention in orthodontic treatment of hypodontia patients.

Orthopedic and orthodontic treatment of Parry-Romberg syndrome

Parry-Romberg syndrome (PRS) is a degenerative disease characterized by progressive hemifacial atrophy of soft and hard tissues. A 10-year-old girl who had been treated for linear scleroderma at the dermatologic department since the age of 9 years visited the orthodontic department. The frontal facial photograph showed mild facial asymmetry. On the left side, mild atrophy of soft tissue, mild enophthalmos, cheek depression, and dry skin with dark pigmentation were observed. The radiograph showed hypoplasia of both the maxilla and mandible on the left side. Intraorally, she was in the mixed dentition with the dental crowding. This case report describes the treatment of a patient with PRS for 7 years. To minimize the effect of progressive atrophy on facial growth, a functional appliance was used. The facial photographs and radiographic records were periodically taken to analyze the progression of PRS. Although it is impossible to prevent the progress of facial asymmetry, it appears to be possible to limit the atrophic effect on the mandible by stimulating the mandibular growth. After stabilization of PRS, orthodontic treatment by fixed appliance was performed. In addition, autologous fat graft was performed 3 times at 6-month intervals. After the treatment, the patient had a confident smile, and facial asymmetry was improved.

Cone-beam computed tomography evaluation of relationship between tongue volume and lower incisor irregularity

The aim of this study was to evaluate the relationship between the tongue volume and lower incisor irregularity, using cone-beam computed tomography (CBCT), and to identify the possible gender differences. CBCT images of 60 patients between 16 and 36 years of age were selected from 1400 sets of images in the database. Tomography was carried out using iCAT® (Imaging Sciences International, Hatfield, Pennsylvania, USA) and segmentation was carried out by using Mimics 10.1 software (Materialise NV, Leuven, Belgium). The tongue volume was calculated by using the volume of the voxels from the scan and the number of voxels selected for a given mask. Lower incisor crowding was measured with the Little's irregularity index and divided into three groups: mild, moderate, and severe. Independent samples t-test, analysis of variance (ANOVA), and Tukey test were used at P < 0.05 level. Pearson correlation coefficients and linear regression model were calculated to determine the correlation between tongue volume and incisor irregularity. No significant gender dimorphism was found for the tongue volume (females: 28.13 ± 8.54 cm(3) and males: 31.02 ± 9.75 cm(3)). According to ANOVA, there was statistically significant difference in the tongue volume measurements among subjects with different levels of irregularity. Tukey analysis indicated that mild irregularity group (33.97 cm(3)) showed higher values for tongue volume than severe irregularity group (26.60 cm(3); P = 0.025). The relationship between incisor irregularity and tongue volume was evaluated for both genders and significant inverse correlation (r = -0.429; P = 0.029) was determined between lower incisor irregularity and tongue volume in males. In female group, no significant correlation was determined between tongue volume and incisor irregularity.

True hemifacial microsomia and hemimandibular hypoplasia with condylar-coronoid collapse: diagnostic and prognostic differences

INTRODUCTION

Long-term results after orthopedic or surgical treatment of hemifacial microsomia (HFM) have shown a tendency toward recurrence of the facial asymmetry. However, the literature contains a number of successful case reports that show surprising changes in the morphology of the condyles. In addition, patients with similar mandibular asymmetries, treated early with surgery, have excellent long-term follow-ups, especially those who have little or no soft-tissue involvement, but only severe mandibular ramal deformities. The phenotypes of these cases are unexpectedly similar, with a consistent collapse of the condyle against the coronoid and a deep sigmoid notch. The objectives of this article were to help distinguish true HFM from this peculiar type of hemimandibular asymmetry morphologically and to quantify their differences before treatement and in the long term.

METHODS

Panoramic radiographs taken at pretreatment and the long-term follow-up of 9 patients with hemimandibular hypoplasia, characterized by the collapse of the condyle against the coronoid, were compared with those of 8 patients with severe type I and type II HFM; these records were collected before and at least 10 years after distraction osteogenesis.

RESULTS

Ratios and angular measurements before and after treatment differed significantly between the 2 groups.

CONCLUSIONS

Perhaps these patients were misdiagnosed and actually had secondary injuries of the condyle, which have a normal functional matrix. Therefore, with growth and functional stimulation, they would tend to grow toward the original symmetry. To make a differential diagnosis between true HFM and this peculiar type of hemimandibular hypoplasia, the collaboration between not only orthodontists and surgeons, but also geneticists and dysmorphologists, is of great importance because of the different prognoses.

A histochemical study on condylar cartilage and glenoid fossa during mandibular advancement

OBJECTIVE

To evaluate cellular hypertrophic activities in the mandibular condylar cartilage (MCC) and the glenoid fossa (GF) during mandibular advancement in the temporomandibular joint (TMJ) of Sprague-Dawley rats, as evidenced by fibroblast growth factor 8 (FGF8).

METHODS AND MATERIALS

Fifty-five female 24-day-old Sprague-Dawley rats were randomly divided into four experimental and control groups, with a mandibular advancement appliance on the experimental rats' lower incisors. The rats were euthanized on days 3, 14, 21, and 30 of the study, and their TMJ was prepared for a immunohistochemical staining procedure to detect FGF8.

RESULTS

FGF8 expression was significantly higher among the experimental rats (P  =  .002). Patterns of ascension and descension of FGF8 expression were similar in experimental and control samples. The results show an overall enhanced osteogenic transition occurring in both the MCC and the GF in experimental rats in comparison with controls. The level of cellular changes in the MCC is remarkably higher than in the GF.

CONCLUSION

In the MCC and the GF, cellular morphologic and hypertrophic differentiations increase significantly during mandibular advancement. It is also concluded that endochondral ossification in the MCC and intramembranous ossification in the GF occur during adaptive remodeling.

Influence of lip closure on alveolar cleft width in patients with cleft lip and palate

Background

The influence of surgery on growth and stability after treatment in patients with cleft lip and palate are topics still under discussion. The aim of the present study was to investigate the influence of early lip closure on the width of the alveolar cleft using dental casts.

Methods

A total of 44 clefts were investigated using plaster casts, 30 unilateral and 7 bilateral clefts. All infants received a passive molding plate a few days after birth. The age at the time of closure of the lip was 2.1 month in average (range 1-6 months). Plaster casts were obtained at the following stages: shortly after birth, prior to lip closure, prior to soft palate closure. We determined the width of the alveolar cleft before lip closure and prior to soft palate closure measuring the alveolar cleft width from the most lateral point of the premaxilla/anterior segment to the most medial point of the smaller segment.

Results

After lip closure 15 clefts presented with a width of 0 mm, meaning that the mucosa of the segments was almost touching one another. 19 clefts showed a width of up to 2 mm and 10 clefts were still over 2 mm wide. This means a reduction of 0% in 5 clefts, of 1-50% in 6 clefts, of 51-99% in 19 clefts, and of 100% in 14 clefts.

Conclusions

Early lip closure reduces alveolar cleft width. In most cases our aim of a remaining cleft width of 2 mm or less can be achieved. These are promising conditions for primary alveolar bone grafting to restore the dental bony arch.

Effects of feeding on non-nutritive sucking habits and implications on occlusion in mixed dentition

BACKGROUND

Several studies have determined the effects of non-nutritive sucking habits on malocclusions, but provided conflicting results.

AIM

To analyse the influence of infant feeding In the presence of non-nutritive sucking habits in children after the first year of life and to assess the effects of non-nutritive sucking habits on occlusion in mixed dentition.

DESIGN

Data were collected by self-reported questionnaire and confirmed by personal interview. Parents of 1451 children (aged 7-11) were asked about their children's infant feeding and non-nutritive sucking habits. A clinical evaluation of dental arches included classification of molar relationship (Angle classification), presence or absence of crossbite and open bite.

RESULTS

Children with bottle or complementary feeding showed a higher risk of acquiring non-nutritive sucking habits after the first year of life (P < 0.01). Non-nutritive sucking habits are associated with a greater risk of crossbite, open bite, Class II molar relationship (P < 0.01).

CONCLUSIONS

Parents should be educated about benefits of the exclusive breast feeding in the first 6 months of age on mixed dentition. The activity of non-nutritive sucking should be diagnosed in a timely manner in order to reduce the development of posterior crossbite, anterior open bite, and Class II molar relationship.

Endocranial shape asymmetries in Pan paniscus, Pan troglodytes and Gorilla gorilla assessed via skull based landmark analysis

Brain shape asymmetries or petalias consist of the extension of one cerebral hemisphere beyond the other. A larger frontal or caudal projection is usually coupled with a larger lateral extent of the more projecting hemisphere relative to the other. The concurrence of these petalial components is characteristic of hominins. Studies aimed at quantifying petalial asymmetries in human and great ape endocasts rely on the definition of the midline of the endocranial surface. Studies of brain material show that, at least in humans, most of the medial surface of the left occipital lobe distorts along the midline and protrudes on to the right side, making it difficult for midline and corresponding left and right reference point identification. In order to accurately quantify and compare brain shape asymmetries in extant hominid species, we propose here a new protocol based on the objective definition of cranial landmarks. We describe and quantify for the first time in three dimensions the positions of frontal and occipital protrusions in large samples of Pan paniscus, Pan troglodytes and Gorilla gorilla. This study confirms the existence of frontal and occipital petalias in African apes. Moreover, the detailed analysis of the 3D structure of these petalias reveals shared features, as well as features that are unique to the different great ape species.

Nasal septal and premaxillary developmental integration: implications for facial reduction in Homo

The influence of the chondrocranium in craniofacial development and its role in the reduction of facial size and projection in the genus Homo is incompletely understood. As one component of the chondrocranium, the nasal septum has been argued to play a significant role in human midfacial growth, particularly with respect to its interaction with the premaxilla during prenatal and early postnatal development. Thus, understanding the precise role of nasal septal growth on the facial skeleton is potentially informative with respect to the evolutionary change in craniofacial form. In this study, we assessed the integrative effects of the nasal septum and premaxilla by experimentally reducing facial length in Sus scrofa via circummaxillary suture fixation. Following from the nasal septal-traction model, we tested the following hypotheses: (1) facial growth restriction produces no change in nasal septum length; and (2) restriction of facial length produces compensatory premaxillary growth due to continued nasal septal growth. With respect to hypothesis 1, we found no significant differences in septum length (using the vomer as a proxy) in our experimental (n = 10), control (n = 9) and surgical sham (n = 9) trial groups. With respect to hypothesis 2, the experimental group exhibited a significant increase in premaxilla length. Our hypotheses were further supported by multivariate geometric morphometric analysis and support an integrative relationship between the nasal septum and premaxilla. Thus, continued assessment of the growth and integration of the nasal septum and premaxilla is potentially informative regarding the complex developmental mechanisms that underlie facial reduction in genus Homo evolution.

The effect of mouth breathing versus nasal breathing on dentofacial and craniofacial development in orthodontic patients

OBJECTIVES/HYPOTHESIS

To determine the effect of mouth breathing during childhood on craniofacial and dentofacial development compared to nasal breathing in malocclusion patients treated in the orthodontic clinic.

STUDY DESIGN

Retrospective study in a tertiary medical center.

METHODS

Clinical variables and cephalometric parameters of 116 pediatric patients who had undergone orthodontic treatment were reviewed. The study group included 55 pediatric patients who suffered from symptoms and signs of nasal obstruction, and the control group included 61 patients who were normal nasal breathers.

RESULTS

Mouth breathers demonstrated considerable backward and downward rotation of the mandible, increased overjet, increase in the mandible plane angle, a higher palatal plane, and narrowing of both upper and lower arches at the level of canines and first molars compared to the nasal breathers group. The prevalence of a posterior cross bite was significantly more frequent in the mouth breathers group (49%) than nose breathers (26%), (P = .006). Abnormal lip-to-tongue anterior oral seal was significantly more frequent in the mouth breathers group (56%) than in the nose breathers group (30%) (P = .05).

CONCLUSIONS

Naso-respiratory obstruction with mouth breathing during critical growth periods in children has a higher tendency for clockwise rotation of the growing mandible, with a disproportionate increase in anterior lower vertical face height and decreased posterior facial height.

Fetal and infant growth patterns of the mandibular symphysis in modern humans and chimpanzees (Pan troglodytes)

Comparison of the early development of the mandibular symphysis between primates and modern humans is of particular interest in human palaeontology. Using geometric morphometric methods, we explored and compared the ontogenetic shape changes of 14 chimpanzee mandibles (Pan troglodytes) against 66 human CT-scanned mandibles over the age range from fetal life to the complete emergence of the deciduous dentition in a visualization incorporating the deciduous tooth arrangement. The results reveal that the symphysis is anteriorly inclined in the youngest chimpanzee fetuses but develops an increasingly vertical orientation up until birth. At the same time, the anterior teeth reorient before a vertical emergence, and a symphyseal tuber appears on the labial side. When the deciduous canine emerges, the symphysis inclines anteriorly again, exhibiting the adult characteristic slope. These two phases are characterized by a repositioning of the simian shelf. Unlike chimpanzees, the human symphysis remains vertical throughout fetal development. However, the combination of morphological changes observed in chimpanzee fetuses is similar to that of modern humans after birth, as the mental region projects forward. By elongating the alveolar process, the inclination of the chimpanzee symphysis could be a key event for emergence of the deciduous canine, as space is lacking at the alveolar ridge in a vertical symphysis once the deciduous incisors and molars have emerged. The repositioning of the simian shelf suggests that the suprahyoid muscles have a significant influence on the anterior growth of the symphysis. The anteroposterior positioning of the basal symphysis in both species may be related to hyoid bone position during ontogeny.

Orthodontics for treating temporomandibular joint (TMJ) disorders

BACKGROUND

Temporomandibular disorders (TMD) relate to discomfort of the temporomandibular joint (TMJ). The disorder is multifactorial with a degree of psychogenic influence varying throughout an individual's life with phases of symptoms affecting the quality of life. In an attempt to treat this complex group of disorders many treatment modalities have been identified some of which are also considered in other Cochrane reviews. The disorder also has a normal cycle of events appearing to spontaneously improve without treatment.

OBJECTIVES

To establish the effectiveness of orthodontic intervention in reducing symptoms in patients with TMD (compared with any control group receiving no treatment, placebo treatment or reassurance) and to establish if active orthodontic intervention leads to TMD.

SEARCH STRATEGY

The Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE and EMBASE were searched. Handsearching of orthodontic journals and other related journals was undertaken in keeping with the Cochrane Collaboration handsearching programme. No language restrictions were applied. Authors of any studies were identified, as were experts offering legal advice, and contacted to identify unpublished trials. Most recent search: 13th April 2010.

SELECTION CRITERIA

All randomised controlled trials (RCTs) including quasi-randomised trials assessing orthodontic treatment for TMD were included. Studies with adults aged equal to or above 18 years old with clinically diagnosed TMD were included. There were no age restrictions for prevention trials provided the follow-up period extended into adulthood. The inclusion criteria required reports to state their diagnostic criteria for TMD at the start of treatment and for participants to exhibit two or more of the signs and/or symptoms. The treatment group included treatment with appliances that could induce stable orthodontic tooth movement. Patients receiving splints for 8 to 12 weeks and studies involving surgical intervention (direct exploration/surgery of the joint and/or orthognathic surgery to correct an abnormality of the underlying skeletal pattern) were excluded. The outcomes were: how well were the symptoms reduced, adverse effects on oral health and quality of life.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in triplicate and independently by three review authors. As no two studies compared the same treatment strategies (interventions) it was not possible to combine the results of any studies.

MAIN RESULTS

The searches identified 284 records from all databases. Initial screening of the abstracts and titles by all review authors identified 55 articles which related to orthodontic treatment and TMD. The full articles were then retrieved and of these articles only four demonstrated any data that might be of value with respect to TMD and orthodontics. After further analysis of the full texts of the four studies identified, none of the retrieved studies met the inclusion criteria and all were excluded from this review.

AUTHORS' CONCLUSIONS

There are insufficient research data on which to base our clinical practice on the relationship of active orthodontic intervention and TMD. There is an urgent need for high quality randomised controlled trials in this area of orthodontic practice.When considering consent for patients it is essential to reflect the seemingly random development/alleviation of TMD signs and symptoms.

Longitudinal growth changes of the cranial base from puberty to adulthood. A comparison of different superimposition methods

OBJECTIVE

To investigate the stability of cranial reference landmarks from puberty through adulthood and to compare the displacement of these landmarks among the superimposition methods of Björk, Ricketts, Steiner, and the proposed tuberculum sella-wing (T-W) reference line.

MATERIALS AND METHODS

The sample consisted of serial lateral cephalometric radiographs of 30 Class II division 1 patients taken at the pretreatment (T1; mean age, 11.98 years), posttreatment (T2; mean age, 15.32 years) and postretention (T3; mean age, 32.12 years) periods. All cephalometric radiographs were superimposed at the cranial base according to the overall superimposition methods of Björk, Ricketts, Steiner, and the T-W method. The horizontal and vertical displacements of cranial landmarks (nasion, wing, tuberculum sella, sella, basion, and pterygomaxillare) were assessed by paired t-test according to Björk's structural method. One-way analysis of variance (ANOVA) was used for comparison of the displacement of cranial landmarks among the superimposition methods.

RESULTS

The tuberculum sella and wing were the most stable cranial landmarks of the cranial base. The stability of sella and pterygomaxillare points were somewhat questionable. Nasion and basion were highly variable. The displacements of all cranial landmarks were similar between the Björk and T-W methods in all study periods. Most of the cranial landmarks displaced similarly in the horizontal direction among the methods. Vertically, the behaviors of the cranial landmarks were frequently different.

CONCLUSIONS

T-W is the most similar superimposition method to Björk's structural method; thus, it is a reliable method for examining overall facial changes.

Relationship between facial morphology on lateral skull radiographs and sEMG activity of neck and trunk muscles in Caucasian adult females. A cross-sectional study

OBJECTIVE

To evaluate whether there is an association between facial morphology on cephalometrics and surface electromyographic (sEMG) recordings of head, neck and trunk muscles.

MATERIALS AND METHODS

31 Caucasian adult females, average age 26 years (range 21-29) underwent lateral skull radiographs in natural head position (mirror position) and the sEMG recordings for the following muscles: masseter, anterior temporal, digastric, posterior cervicals, sternocleidomastoid, and upper and lower trapezius. All muscles were monitored in the mandibular rest position, and during maximal voluntary clenching (MVC).

RESULTS

Spearman's correlation coefficient revealed significant correlations (P<0.01): (i) between the variables controlling mandibular position, and the inclination of the lower incisors, and the sEMG activity of the trapezius; (ii) between the sEMG activity of sternocleidomastoid and the variables indicating the height of the mandibular ramus; (iii) between the sEMG activity of anterior temporal and the incisive angle, the inclination of the upper incisors and the maxillary base length, and (iv) between the sEMG activity of cervical muscles and the anterior cranial base length.

CONCLUSIONS

Some associations between cephalometric variables and sEMG of the neck and trunk muscles were observed. However, in view of the cross-sectional nature of the study and the limited sample, no conclusion was possible about the mechanism concerning these results. Future longitudinal studies are required to investigate the "mechanism at work".

The effect of the Botulinum toxin-A on craniofacial development: an experimental study

In this study, we developed a novel experimental model to evaluate muscular action on bone formation and remodeling by the help of Botulinum toxin-A (BTX). Forty-nine 15-day-old male Wistar rats were put into 4 groups randomly. Group 1 was the control group. BTX 0.4 IU (0.05 mL) was injected into the right masseter muscle in group 2 and into right temporalis muscle in group 3. The same volume of sterile saline was given into the both above-mentioned muscles in group 4. At the end of the fourth month, all animals were killed. Histology and weight of the masseter and temporalis muscles were studied. Thirty different osteometric measurements were also taken from skulls. Significant atrophy in BTX injected muscles was observed in groups 2 and 3. In group 4 (saline injection), only few osteometric measurements were significantly reduced, indicating the effect of the injection itself. Both groups 2 and 3 have apparent decrease in nasal bone, premaxilla, maxilla, and zygomatic dimensions on the injected side. When masseter group was compared with control and saline groups, no significant difference was found in skull base dimensions and mandibular length. In contrast, temporal group has also shown significant decrease in skull base dimensions. Our conclusions are as follows: (1) With this model, it is possible to study muscular action on bone formation and modeling without any surgical intervention, that is, by avoiding surgical artifacts, such as scar and contracture; (2) denervation of the skeletal muscles with BTX during the growing phase does effect bone development in a negative way; (3) pediatric use of the BTX deserves reevaluation under the light of these findings.

Orthodontic treatment in children to prevent sleep-disordered breathing in adulthood

The purpose of this article is to review human craniofacial growth and development, especially the growth of the mandible, to clarify the relationship between obstructive sleep apnea (OSA) syndrome and craniofacial abnormality, and finally, to propose the hypothesis that negative pressure produced in the chest of the OSA child inhibits the growth of the mandible. Recently, the development of diagnosis and treatment of OSA syndrome has progressed rapidly; however, the prevention of OSA syndrome was merely seen. Craniofacial abnormality is reported as one of the causes of OSA syndrome. If craniofacial abnormality is determined only by genetics, it is difficult to manage the craniofacial skeleton to prevent OSA syndrome. The role of epigenetic factors on craniofacial growth and development is still controversial. However, if we stand on the functional matrix hypothesis, we can manage not only growth of the mandible but also the craniofacial skeleton as a whole. The author proposes the hypothesis that the negative pressure produced in the chest prohibits the growth of the mandible even if the patients have a capacity for growth and development; therefore, if this negative pressure disappears because of the removal of the tonsil and/or adenoids or by an orthodontic treatment to make a patency of the airway, the mandible may grow normally, and we can prevent or reduce a number of OSA syndromes in the future.

The aponeurotic tension model of craniofacial growth in man

Craniofacial growth is a scientific crossroad for the fundamental mechanisms of musculoskeletal physiology. Better understanding of growth and development will provide new insights into repair, regeneration and adaptation to applied loads. Traditional craniofacial growth concepts are insufficient to explain the dynamics of airway/vocal tract development, cranial rotation, basicranial flexion and the role of the cranial base in expression of facial proportions. A testable hypothesis is needed to explore the physiological pressure propelling midface growth and the role of neural factors in expression of musculoskeletal adaptation after the cessation of anterior cranial base growth. A novel model for craniofacial growth is proposed for: 1. brain growth and craniofacial adaptation up to the age of 20; 2. explaining growth force vectors; 3. defining the role of muscle plasticity as a conduit for craniofacial growth forces; and 4. describing the effect of cranial rotation in the expression of facial form.Growth of the viscerocranium is believed to be influenced by the superficial musculoaponeurotic systems (SMAS) of the head through residual tension in the occipitofrontalis muscle as a result of cephalad brain growth and cranial rotation. The coordinated effects of the regional SMAS develop a craniofacial musculoaponeurotic system (CFMAS), which is believed to affect maxillary and mandibular development.

Fatores interferentes na alimentação de crianças de 17 a 25 meses de uma creche municipal

OBJETIVO: verificar fatores interferentes no padrão de alimentação de crianças de 17 a 25 meses. MÉTODOS: dados de avaliações fonoaudiológicas de todas as crianças do berçário (n=14) de uma creche no município de Bauru/SP. Aplicação de questionário aos pais a respeito das condições de saúde geral e desenvolvimento neuromotor, aleitamento natural ou artificial, hábitos orais e problemas respiratórios. Analisou-se a morfofuncionalidade dos constituintes do sistema estomatognático e características clínico-fisiológicas da mastigação e deglutição. A análise estatística foi descritiva. RESULTADOS: constatou-se alteração em diversos aspectos da saúde nas crianças (92,8%); presença de má oclusão (28,6%); alterações morfológicas para lábio (21,4%) e língua (21,4%); alterações de tonicidade de bochechas (57,1%), mento (21,4%) e lábios (42,8%); respiração oral ou oronasal (42,8%); alterações na mastigação (35,7%) e na deglutição de sólido (50%) e líquido (42,8%). CONCLUSÃO: para esse grupo, a presença de hábitos orais, assim como as alterações morfológicas e de tonicidade influenciam o padrão de alimentação das crianças analisadas, evidenciando a necessidade de prevenir e detectar precocemente tais fatores para que a alimentação nas crianças ocorra de forma adequada, promovendo assim condições de saúde para um desenvolvimento hígido.

Pacifier use as a risk factor for reduction in breastfeeding duration: a systematic review

This systematic review of literature proposes to establish whether pacifier use is a risk factor for a reduction in the duration of breastfeeding. A search of the Medline and Lilacs databases was carried out for articles published between 1996 and 2006 using the following descriptors: "breastfeeding" and "pacifier". Articles were excluded if they: had no open access abstracts; did not contain estimators testing the degree of association between breastfeeding duration and pacifier use; involved a follow-up loss of greater than 20%; were written in languages other than Portuguese, English and Spanish; covered specific population categories, such as pre-term babies or mothers who experienced difficulty breastfeeding; or were based on information provided by the mother or a health care professional. Nineteen articles were chosen according to the criteria outlined above; of these, one was a randomized clinical trial, eleven were prospective cohort studies and seven were cross sectional studies. The review concludes that pacifier use is a risk factor for breastfeeding duration, although the performance mechanism remains obscure. Other risk factors relate to the children, their parents and the hospital care they receive regarding the early interruption of breastfeeding. There is a need to standardize the methodology for investigating the association between pacifier use and breastfeeding duration, in order to provide scientific knowledge on this subject.

Experimental study on the influence of facial muscle activity on the facial mesostructure bones in rabbits

Based on the functional matrix concept, scientists developed the hypothesis that soft tissue acting on certain bone pieces determines the process of facial growth. The possibility to modify muscle influence in the phase of facial development, or in postoperative of corrective surgery is of great preventive importance and it should be better investigated, since it could reduce the number and impact of these procedures.

Study design

experimental in rabbits.

Aim

to estimate the relevance of facial muscle activity on facial bones in lab rabbits.

Materials and Methods

37 rabbits of two months of age were studied, divided in a study group and a control group, were followed up for a period of 4 months. The study group animals had their facial nerves cut at the cervical root in one side. The facial mesostructure of the animals was removed in block for later morphometric studies through computer graphics made out of the digital pictures of the specimens. Results were submitted for comparative statistical analysis.

Conclusion

The lack of muscle activity in half of the face produces an ipsilateral shift of the facial mesostructure in developing rabbits.

Predicting skull loading: applying multibody dynamics analysis to a macaque skull

Evaluating stress and strain fields in anatomical structures is a way to test hypotheses that relate specific features of facial and skeletal morphology to mechanical loading. Engineering techniques such as finite element analysis are now commonly used to calculate stress and strain fields, but if we are to fully accept these methods we must be confident that the applied loading regimens are reasonable. Multibody dynamics analysis (MDA) is a relatively new three dimensional computer modeling technique that can be used to apply varying muscle forces to predict joint and bite forces during static and dynamic motions. The method ensures that equilibrium of the structure is maintained at all times, even for complex statically indeterminate problems, eliminating nonphysiological constraint conditions often seen with other approaches. This study describes the novel use of MDA to investigate the influence of different muscle representations on a macaque skull model (Macaca fascicularis), where muscle groups were represented by either a single, multiple, or wrapped muscle fibers. The impact of varying muscle representation on stress fields was assessed through additional finite element simulations. The MDA models highlighted that muscle forces varied with gape and that forces within individual muscle groups also varied; for example, the anterior strands of the superficial masseter were loaded to a greater extent than the posterior strands. The direction of the muscle force was altered when temporalis muscle wrapping was modeled, and was coupled with compressive contact forces applied to the frontal, parietal and temporal bones of the cranium during biting.