Evaluation of facial soft tissue asymmetric changes in Class III patients after orthognathic surgery using three-dimensional stereophotogrammetry.

The aim of this study was to investigate changes in facial soft tissue asymmetry over time after orthognathic surgery in Class III patients using three-dimensional stereophotogrammetry. The study included 101 patients with a skeletal Class III malocclusion (72 female, 29 male; age range 19-53 years, mean age 28.6 years) who underwent orthognathic surgery. The minimum follow-up was 12 months. Three-dimensional photographs were acquired using the 3dMDtrio stereophotogrammetry system, and 21 anthropometric landmark positions were evaluated at three time points: before surgery (T0), 6 months (T1) and 12 months (T2) after surgery. Facial asymmetry was assessed and classified as follows: 0-2 mm, mild; 2-5 mm, moderate;> 5 mm, severe. The average distance for whole face asymmetry differed between T0 (median 0.76 mm) and T1 (median 0.70 mm); however, there was no statistically significant difference at any time point. The chin volume asymmetry score differed significantly between T0 (median 1.11 mm) and T1 and T2 (median 1.08 mm for both; P < 0.001 and P = 0.001, respectively), but not between T1 and T2 (P = 0.061). The study findings indicate that the asymmetry of the facial soft tissues has the potential to return after 6 months, without reaching the baseline.

An exploration of adolescent facial shape changes with age via multilevel partial least squares regression.

BACKGROUND AND OBJECTIVES: Multilevel statistical models represent the existence of hierarchies or clustering within populations of subjects (or shapes in this work). This is a distinct advantage over single-level methods that do not. Multilevel partial-least squares regression (mPLSR) is used here to study facial shape changes with age during adolescence in Welsh and Finnish samples comprising males and females. METHODS: 3D facial images were obtained for Welsh and Finnish male and female subjects at multiple ages from 12 to 17 years old. 1000 3D points were defined regularly for each shape by using "meshmonk" software. A three-level model was used here, including level 1 (sex/ethnicity); level 2, all "subject" variations excluding sex, ethnicity, and age; and level 3, age. The mathematical formalism of mPLSR is given in an Appendix. RESULTS: Differences in facial shape between the ages of 12 and 17 predicted by mPLSR agree well with previous results of multilevel principal components analysis (mPCA); buccal fat is reduced with increasing age and features such as the nose, brow, and chin become larger and more distinct. Differences due to ethnicity and sex are also observed. Plausible simulated faces are predicted from the model for different ages, sexes and ethnicities. Our models provide good representations of the shape data by consideration of appropriate measures of model fit (RMSE and R2). CONCLUSIONS: Repeat measures in our dataset for the same subject at different ages can only be modelled indirectly at the lowest level of the model at discrete ages via mPCA. By contrast, mPLSR models age explicitly as a continuous covariate, which is a strong advantage of mPLSR over mPCA. These investigations demonstrate that multivariate multilevel methods such as mPLSR can be used to describe such age-related changes for dense 3D point data. mPLSR might be of much use in future for the prediction of facial shapes for missing persons at specific ages or for simulating shapes for syndromes that affect facial shape in new subject populations.

Multilevel principal components analysis of three-dimensional facial growth in adolescents.

BACKGROUND AND OBJECTIVES: The study of age-related facial shape changes across different populations and sexes requires new multivariate tools to disentangle different sources of variations present in 3D facial images. Here we wish to use a multivariate technique called multilevel principal components analysis (mPCA) to study three-dimensional facial growth in adolescents. METHODS: These facial shapes were captured for Welsh and Finnish subjects (both male and female) at multiple ages from 12 to 17 years old (i.e., repeated-measures data). 1000 "dense" 3D points were defined regularly for each shape by using a deformable template via "meshmonk" software. A three-level model was used here, namely: level 1 (sex/ethnicity); level 2, all "subject" variations excluding sex, ethnicity, and age; and level 3, age. The technicalities underpinning the mPCA method are presented in Appendices. RESULTS: Eigenvalues via mPCA predicted that: level 1 (ethnicity/sex) contained 7.9% of variation; level 2 contained 71.5%; and level 3 (age) contained 20.6%. The results for the eigenvalues via mPCA followed a similar pattern to those results of single-level PCA. Results for modes of variation made sense, where effects due to ethnicity, sex, and age were reflected in modes at appropriate levels of the model. Standardised scores at level 1 via mPCA showed much stronger differentiation between sex and ethnicity groups than results of single-level PCA. Results for standardised scores from both single-level PCA and mPCA at level 3 indicated that females had different average "trajectories" with respect to these scores than males, which suggests that facial shape matures in different ways for males and females. No strong evidence of differences in growth patterns between Finnish and Welsh subjects was observed. CONCLUSIONS: mPCA results agree with existing research relating to the general process of facial changes in adolescents with respect to age quoted in the literature. They support previous evidence that suggests that males demonstrate larger changes and for a longer period of time compared to females, especially in the lower third of the face. These calculations are therefore an excellent initial test that multivariate multilevel methods such as mPCA can be used to describe such age-related changes for "dense" 3D point data.

3D follow-up study of facial asymmetry after developmental dysplasia of the hip.

OBJECTIVES: To evaluate the change in facial asymmetry among subjects treated for developmental dysplasia of the hip (DDH) from childhood to adolescence. SETTING AND SAMPLE POPULATION: A total of 39 adolescents (26 females and 13 males), born and treated for DDH during 1997-2001, participated in the first examination in 2007 (T1; at the age of 8.2) and in the follow-up in 2016 (T2; at the age of 16.6). MATERIAL AND METHODS: In this longitudinal study, three-dimensional (3D) images were taken using a 3DMD face system based on a stereophotogrammetric method. Facial asymmetry was determined as the average distance (mm) calculated between the original and superimposed mirrored face and the symmetry percentage (%) calculated as the face area where the distance between the original face and the mirrored surface does not exceed 0.5 mm. RESULTS: Results showed increased asymmetry from T1 to T2. The average distance increased for whole face (from 0.51 mm to 0.59 mm, P = .001), upper face (from 0.41 mm to 0.49 mm, P = .005), mid-face (from 0.48 mm to 0.57, P = .002) and lower face (from 0.74 mm to 0.85 mm, P = .147). Facial symmetry percentage decreased for whole face from 61.23% to 55.38% (P = .011), for upper face from 69.27% to 62.24% (P = .005) and for mid-face from 62.29% to 55.63% (P = .007) and for lower face from 43.37% to 42.19% (P = .66). CONCLUSION: Facial asymmetry increases from childhood to adulthood in subjects treated for DDH. Orthodontic treatment does not eliminate this asymmetric facial growth.

Effects of loading on chondrocyte hypoxia, HIF-1α and VEGF in the mandibular condylar cartilage of young rats.

OBJECTIVES: To investigate hypoxia-inducible factor 1-alpha (HIF-1α) and vascular endothelial growth factor (VEGF) expression under altered loading, and to explore the relationship between loading and hypoxia in the mandibular condylar cartilage of young rats. SETTING AND SAMPLE POPULATION: Eighty Sprague-Dawley rats. MATERIAL AND METHODS: The reduced loading group was fed soft food, and their incisors were cut to avoid occlusal contact. The increased loading group was fed hard food and had forced jaw-opening. Ten rats from each group (n = 10) were sacrificed at 12, 24, 48, and 96 hours after initiation of the experiment. Pimonidazole hydrochloride (Hypoxyprobe-1, HP-1) was used as a hypoxia marker to confirm the hypoxic state. Hypoxic chondrocytes as indicated by HP-1, HIF-1α and VEGF protein expressions were recognized by immunohistochemical detection. HIF-1α and VEGF mRNA expressions were detected by semi-quantitative RT-PCR. RESULTS: Hypoxyprobe-1 was confined in the upper layers of cartilage, and was most strongly expressed in the weight-bearing area of TMJ at 12 and 96 hours. Staining of HIF-1α and VEGF was most strongly expressed in the chondrocytes of the fibrous and proliferative layer at all time points. Furthermore, expressions were also displayed in the hypertrophic and calcified layers at 48 and 96 hours. The expressions of HIF-1α and VEGF mRNA were higher in the increased loading group than in the reduced loading group at 48 and 96 hours (P < . 05). CONCLUSION: Mechanical loading seems to directly induce weight-bearing area hypoxia followed by new vessel formation, which indicates that these factors are related and important for the development of cartilage.

The Erasmus programme for postgraduate education in orthodontics in Europe: an update of the guidelines.

In 1989, the ERASMUS Bureau of the European Cultural Foundation of the Commission of the European Communities funded the development of a new 3-year curriculum for postgraduate education in orthodontics. The new curriculum was created by directors for orthodontic education representing 15 European countries. The curriculum entitled 'Three years Postgraduate Programme in Orthodontics: the Final Report of the Erasmus Project' was published 1992. In 2012, the 'Network of Erasmus Based European Orthodontic Programmes' developed and approved an updated version of the guidelines. The core programme consists of eight sections: general biological and medical subjects; basic orthodontic subjects; general orthodontic subjects; orthodontic techniques; interdisciplinary subjects; management of health and safety; practice management, administration, and ethics; extramural educational activities. The programme goals and objectives are described and the competencies to be reached are outlined. These guidelines may serve as a baseline for programme development and quality assessment for postgraduate programme directors, national associations, and governmental bodies and could assist future residents when selecting a postgraduate programme.

Facial morphology of Finnish children with and without developmental hip dysplasia using 3D facial templates.

BACKGROUND: Developmental dysplasia of the hip (DDH) is a condition that affects the femoral head and the acetabulum and leads to hip subluxation and dislocation. Infants with DDH are usually treated using splints that immobilize their hip joint and are forced on their back for long periods of time. The link between positioning and facial asymmetries is poorly understood. OBJECTIVE: To compare the facial morphologies of children with DDH to a group of healthy controls. SUBJECTS AND METHODS: Fifty-six Finnish patients born with DDH were matched on the basis of gender and age to a control group. Three-dimensional surface images were captured using the 3dMDface system. Using RF6 PP2 software, anthropometric landmarks were plotted and used to calculate asymmetry based on 3D co-ordinates in a reference framework. RESULTS: There was statistically significant difference between all paired facial shells. Relative to the control group, DDH boys and girls presented a chin-point deviation to the right, a more prominent left orbital ridge, a more protrusive nose and upper lip. The gender-specific subgroups show a similarity of 66.54 and 65.22% in girls and boys, respectively. CONCLUSIONS: Patients with DDH present a facial asymmetry when compared to healthy controls. Gender characteristics are marked whether subjects are affected with DDH or not. Three-dimensional surface imaging is a powerful diagnostic and research tool.

MMP-3 and -8 expression is found in the condylar surface of temporomandibular joints with internal derangement.

BACKGROUND: Internal derangement is one of the most common disorder of the temporomandibular joint (TMJ). The aim of this study was to investigate the associations of matrix metalloproteinase (MMP)-3 and -8 expression in articular condylar surface with different stages of TMJ internal derangement according to Wilkes (Minn Med, 1978; 61: 645-52) and osteoarthrosis (OA) according to Dijkgraaf et al. (J Oral Maxillofac Surg, 1995; 53: 1182-92). METHODS: The study was based on 54 condylar specimens obtained during TMJ surgery. Immunohistochemistry using antibodies specific to MMP-3 and -8, represented in cartilage destruction, was carried out. RESULTS: In all tissue specimens, MMP-3 expression was intense in the surface layer but showed less intensive staining in the deeper layers. Some MMP-8 expression was also seen. The severity of TMJ internal derangement, however, did not seem to have a statistically significant correlation (P<0.05) with the expression of these enzymes. CONCLUSION: The study confirms that distinct expression of MMP-3 and -8 is found in the condylar surface of TMJs with internal derangement.

Dental maturation in children with shunt-treated hydrocephalus.

OBJECTIVE: The aim of this study was to examine the relationship between dental maturation and somatic development and to discover their possible deviations in children with shunt-treated hydrocephalus. DESIGN: Radiographs (orthopantomogram and hand-wrist radiograph) from children with shunt-treated hydrocephalus were analyzed with respect to the dental maturation and compared with values of an age- and sex-matched control group and population standards. PATIENTS: Forty-one children with shunt-treated hydrocephalus (27 boys and 14 girls) aged from 5 to 16 years (median age 11.0 years). RESULTS: The mean deviation of dental age from chronological age was significantly greater in the hydrocephalic group than in the control group. The mean value of dental age deviation was advanced in early pubertal stages but reduced in later pubertal stages. CONCLUSIONS: These findings can be explained by changes in the endocrinological conditions, which are due to disturbed pituitary secretion. The present results could also partly reflect an adaptable developmental pathway in an otherwise strictly genetically determined process.

The relationship of handedness to asymmetry in the occlusal morphology of first permanent molars.

Handedness has been shown to be related to a number of systematic asymmetries in body dimensions, dermatoglyphic patterns and cerebral morphology. The aim here was to compare linear and angular tooth crown asymmetries of the permanent molars in healthy right-handed and left-handed subjects. The material comprised 27 children with recorded concordant left-side dominance of hand, eye and foot. The controls were an age- and sex-matched group with right side dominance. The material is based on the Collaborative Perinatal Project where detailed medical records and the dentitions, including accurate dental impressions, of over two thousand American children were examined in the USA in the sixties. Machine vision technique was used to obtain accurate three-dimensional information from the occlusal surfaces of the first permanent upper and lower molars. The directional asymmetry values of angular measurements of mandibular first molars showed evidence of asymmetry of opposite direction between the two examined groups. The results indicate that occlusal morphology of first permanent molars may be affected by handedness, and this tendency is most evident in the angular measurements of the mandibular molars. Fluctuating asymmetry did not differ significantly between the examined groups.

Frontal head posture in shunt-treated hydrocephalic patients.

OBJECTS: The aim of this study was to evaluate frontal head posture in shunt-treated hydrocephalic patients and its relation to the sidedness of the shunt device. METHODS: Natural head position and frontal cephalograms of 55 shunt-treated Finnish hydrocephalic patients and 33 healthy Finnish subjects were analysed using a computerised digitising program (X-METRIX). The following reference angles were used: ORB/HOR, indicating the head position related to the true horizontal; CER/VER, indicating the cervical position related to the true vertical; and CER/CR, indicating the craniocervical position. CONCLUSIONS: The results showed an increased skewness of the head in the shunt-treated subjects, which was not related to the shunt side.

Unilateral masticatory function changes the proteoglycan content of mandibular condylar cartilage in rabbit.

Unilateral masticatory function was induced in 10-day-old rabbits by grinding the right side molars out of occlusion under general anesthesia. The grinding procedure was repeated twice a week thereafter. They were killed at the ages of 25 and 35 days. Rabbits of the same age with uninterfered occlusions served as controls. The changes in articular cartilage of the mandibular condyle were studied biochemically and histochemically. There was a significant decrease in the proteoglycan content of the condylar cartilage in both groups of animals subjected to molar grinding compared to the animals with untouched occlusions. Especially the amount of aggregating proteoglycans was reduced. The condylar cartilage matrix synthesis is sensitive to loading produced by masticatory function during growth. The mechanical properties of the articular cartilage after a period of unilateral mastication will be impaired and it is possible that this makes the joint cartilage more susceptible to pathological events.

Location of the glenoid fossa after a period of unilateral masticatory function in young rabbits.

Changes in glenoid fossa position and skull morphology after a period of unilateral masticatory function were studied. The right-side maxillary and mandibular molars in twenty-seven 10-day-old rabbits were ground down under general anaesthesia. The procedure was repeated twice a week, until the rabbits were 50 days old. Fourteen rabbits were then killed and 13 left to grow to age 100 days. Nine 50-day-old and sixteen 100-day-old rabbits with unmodified occlusions served as controls. Three-dimensional measurements were made using a machine-vision technique and a video-imaging camera. The glenoid fossa position become more anterior in both groups of animals subjected to molar grinding as compared with controls (P < 0.01 in the 50-day-old group and P < 0.05 in 100-day-old group). In the 100-day-old group the right-side fossa was also in a more inferior position (P < 0.01). The glenoid fossa was more anteriorly located on the right than on the left side of individual animals in the group in which the right-side molars had been ground down (P < 0.001).

Cervical headgear therapy as a factor in obstructive sleep apnea syndrome.

PURPOSE: Obstructive sleep apnea syndrome (OSAS) has been a subject of increasing interest from the orthodontic point of view, but less attention has been paid to the possible influence of orthodontic treatment on its occurrence. The aim here was to study possible associations between the use of cervical headgear and nocturnal cessations of airflow and the severity of the latter. METHODS: The subjects were 30 children (12 boys, 18 girls, mean age 8.2, sd 1.61 years), divided into three groups: a group of 10 children undergoing headgear therapy, selected for this examination because of symptoms of OSAS while using headgear, an age-matched control group of 10 healthy children and a group of 10 with OSAS. Standard cephalograms of the headgear group prior to the orthodontic therapy and the corresponding cephalograms of healthy controls were analysed. A polygraphic (PG) sleep evaluation was used to assess the tendency for OSAS. Apnea and hypopnea periods were summated as apnea index (AI) and number of desaturations as desaturation index (ODI). All the subjects spent one night sleeping under laboratory conditions, those with orthodontic treatment spending the first half of the night with the headgear and the latter half without. RESULTS: The position of the mandible was found to be slightly more posterior in the headgear group than in the control group. The children in the headgear group were found to have significantly more apnea/hypopnea periods during the hours when the appliance was used, and the ODI-index showed increased values in this group. CONCLUSIONS: We suggest that headgear therapy may contribute to the occurrence of sleep apnea, when a strong predisposition, such as mandibular retrognathia to the development of upper airway occlusion already exists.

Comparison of amounts and properties of collagen and proteoglycans in condylar, costal and nasal cartilages.

In this study we compared the compositions of extracellular matrices of condylar, costal and nasal cartilages to characterize differences in growth patterns in relation to matrix composition. Condylar, costal and nasal cartilages of 25- and 35-day-old rabbits were extracted and subjected to bio- and histochemical analysis to determine total amounts of collagen and amounts and aggregating properties of proteoglycans. We found that proteoglycan content and aggregate formation were greatest in nasal cartilage, and lower in costal and markedly lower in condylar cartilage. The amount of proteoglycans increased by varying amounts in all samples with age. Collagen content was highest in costal cartilage. In 25-day-old rabbits the quantity of collagen in condylar cartilage exceeded that in nasal cartilage. In 35-day-old rabbits the quantities were nearly the same. It is suggested that collagen does not only provide tensile strength, but counteracts forces responsible for interstitial growth such as osmotic pressure. Based on the results, it seems that the amount of proteoglycans is greater in cartilages, which have greater independent growth potential. Variations in increase in amount of proteoglycans with age could reflect differences in the timing of growth of such cartilages.

Effect of cytochalasin D on articular cartilage cell phenotype and shape in long-term organ culture.

It has been documented, on the basis of cell culture experiments, that cytochalasin treatment promotes a round cell shape in chondroblast cultures by altering the cytoskeleton, and that it simultaneously alters the balance between production of type I and type II collagens. The aim in this study was to monitor the deposition of pro-type-I and type II collagens, and possible changes in articular cartilage layers in the mandibular condyle of the mouse under the influence of Cytochalasin D (CD) when total craniomandibular joints of 5-day-old mice were cultured in one block. The experimental group comprised 20 Balb/c mice of both sexes. Twenty in vitro controls were cultured without the administration of cytochalasin. The mice in the third group were used as in vivo controls. The cells in the prechondroblast layer responded with a rapid change in shape when treated with CD and assumed a rounded morphology. The total thickness of the cell layer was reduced at 7 days. Immunostaining against pro-type-I collagen was intense in the narrow fibrous and prechondroblast layers in the CD-treated group, whereas the stained area was wider and the staining gradually reduced in the deeper cartilage layers in the in vitro controls. Staining against type II collagen became weaker at the end of the culturing period of the CD-treated group, whereas in the in vitro controls the staining against type II collagen was clearly visible at all observation times. These phenomena can be explained by changes in differentiation and the altered cell cycle of the chondroblasts in organ culture under the influence of CD.

Changes in proteoglycan and collagen content in the mandibular condylar cartilage of the rabbit caused by an altered relationship between the condyle and glenoid fossa.

Twenty 5-day-old New Zealand rabbits underwent surgery to induce premature synostosis of the cranial sutures, resulting in posterior displacement of the glenoid fossa. Twenty sham-operated rabbits served as controls. The animals were killed at age 15 days for histochemical and biochemical analyses. The collagen content of the superior region of the condyle determined biochemically was lower in treated animals than in controls. Biochemical and histochemical analyses revealed the proteoglycan content to be significantly reduced in the superior region of the condyle (P < or = 0.001). Low levels of aggregating proteoglycans were seen. Since levels of aggregating proteoglycans decreased, catabolism must have exceeded their synthesis or the monomers must have been unable to aggregate and escaped from the tissue. It is concluded that an experiment in which the location of the mandibular condyle in the glenoid fossa is changed, while causing marked reductions in amounts of both collagen and proteoglycans in the cartilage tissue of the mandibular condyle, will also induce changes resembling those observed in animal models of arthritis. It is possible that the two phenomena have similar mechanisms.

Asymmetry in the occlusal morphology of first permanent molars in 45,X/46,XX mosaics.

The genetic control of dental morphology is affected by various chromosomal aberrations, and morphological changes familiar to specific aneuploidies can be distinguished in many cases. Asymmetry between bilateral teeth in the dental arch in laboratory animals shows increased expression after exposure to external stress during development. Bilateral asymmetry in occlusal cuspal morphology has not been widely used as a means of odontometric examination, partly because accurate and reliable methods are not commonly available. The aim here was to examine linear and angular variables of the occlusal morphology of maxillary and mandibular first permanent molars in three dimensions in individuals with 45,X/46,XX mosaicism and to find out if this aneuploidism causes deviations from normal development and increased asymmetry in bilateral variables of the occlusal surface. The participants were five females with 45,X/46,XX chromosome constitution, whose karyotypes were confirmed by cytogenetic tests of skin fibroblasts. The controls were 10 first-degree female relatives of the mosaic patients with normal 46,XX chromosome constitution. The method of measuring the three-dimensional morphology of occlusal surfaces was based on a machine-vision technique using a single video-imaging camera. An apparent increase in asymmetry of occlusal morphology in first permanent molars in 45,X/46,XX mosaics was found. As there was evidence of directional asymmetry, it is possible that different cell lines regulated by discrete genes cause the directionality.

Effect of edentulousness on mandibular size and condyle-fossa position.

Modern imaging methods make possible the more precise examination of the complicated bony structure of the temporomandibular joint (TMJ) and the performance of cephalometric analysis. The aim of our study was to analyse the effect of edentulousness on the mandibular size and the condyle-fossa position using roentgencephalograms and axial computed tomography (CT) scans. The study group consisted of 20 edentulous patients (14 women, six men, mean age 60 years) whose mean period of edentulousness was 20 years (range 3-34 years). A CT examination of their TMJs was performed and roentgen-cephalograms in 16 of this group were taken after prosthetic treatment. Sixteen dental students were chosen according to sex as controls. Earlier CT scans of 49 dentate subjects of both sexes were used as controls for the analysis of bicondylar asymmetry. The position of the glenoid fossa was more anterior in edentulous subjects than in dentate ones and its anterior position correlated significantly (P < 0.02) with the period of edentulousness, a finding which has not been confirmed before. It can be concluded that the fossa is a remodelling unit as a part of the functional entity when the function is altered dramatically as in the case of edentulous patients.

Normal and increased functional asymmetries in the craniofacial area.

Normal asymmetry in the area of the craniofacial skeleton can be directional or fluctuating in nature. Directionality can in principle be found in three dimensions: anteroposterior, cranio-caudal, and asymmetries in the left-right dimension. When it comes to directional left right differences, an explanation has been difficult to find, although expressions of this type are obvious. Recent findings made in molecular genetics strongly support the genetic inheritance pattern of laterality. When functionally increased asymmetries of facial structures are concerned, it is often difficult to determine the exact contribution of each factor involved. In the light of recent experimental data, however, it seems that the influence of occlusion on the development of balanced facial structures is highly important during the early periods of life. A review of these factors is given in this article.