Biomedical subjects

B Prahl-Andersen

Publications and source records attributed to B Prahl-Andersen.

At least 55 records · Page 3Linked to original sources

PubMed1998

Alveolar and skeletal dimensions associated with overbite.

The aim of this study was to investigate whether in the maxilla and in the mandible the structure of the anterior medial sagittal alveolar and basal bone is related to the overbite. A total of 460 untreated adult subjects were divided into four groups with either deep bite, normal overbite, end-to-end bite, or open bite and were compared. The overbite, lower face height, and anterior alveolar and basal midsagittal cross-sectional areas from the maxilla and the mandible were assessed on lateral cephalometric radiographs. An index was calculated, dividing the sagittal by the vertical dimension of the midsagittal cross-sectional area. A deeper bite coincided with smaller lower face height, larger alveolar and basal areas, and a more widened shape of the symphysis. If the lower face height was introduced as a covariable, the open bite group showed significantly smaller maxillary and mandibular alveolar and basal cross-sectional areas compared with the end-to-end group, the normal overbite group, or the deep bite group. Vertical variation of the overbite probably coincides with a relative hyperdevelopment or hypodevelopment of the symphysis.

Adolescent↗

PubMed1997

Clinical relevance of third permanent molars in relation to crowding after orthodontic treatment.

OBJECTIVES: The purpose of this study was to determine the relationship between dental crowding and the clinical presence or absence of third permanent molar teeth. METHODS: Ninety-nine patients were analysed before and after orthodontic treatment and at least three years after the end of retention. The sample consisted of four groups: subjects whose third permanent molar teeth had erupted into the mouth, were non-erupted, were extracted, and were congenitally absent. Arch Length Discrepancy, Irregularity Index and observer bias were examined. Multivariate analysis of variance with repeated measurements was used to analyse differences between the four groups. RESULTS: Significant differences in Arch Length Discrepancy during time were shown between the premolar segment and the frontal area. The group with third permanent molar teeth congenitally missing showed a significant higher positive Arch Length Discrepancy in the premolar segment of the upper jaw. No significant differences in Irregularity Index were found between the third molar groups. CONCLUSIONS: It can be concluded that there is no relation between crowding and the presence or absence of third permanent molar teeth.

Adolescent↗

PubMed1997

Analysis of cohort effects in mixed longitudinal data sets.

Mixed longitudinal designs are among the most efficient for the study of growth and developmental processes. In this approach, one studies several (birth) cohorts, each for a relatively short length of time, and then links the growth curves for the individual cohorts together to obtain the growth curve for the entire length of time spanned by the ages of the subjects in all cohorts. Thus, e.g., in the Nijmegen Growth Study, three cohorts were each studied for 5 years, the intent being to join the three curves together to form a single curve covering the entire period from 4 to 14 years of age. In order for this approach to be valid, there either should be no cohort effects (secular trends) or the fitted curve must be adjusted in some way to correct for such effects if they exist. The question thus arises as to how one should test for the presence of cohort effects and what one should do about them if found. The problems which may arise using height and weight data from the Nijmegen Growth Study are illustrated. In particular for girls, height and weight both show cohort effects (at 9.25 years of age) when the raw data are used. If, however, the observed data are used to estimate the values at the target age, and these values are used in the comparison, differences between the cohorts are no longer significant. The problems are further illustrated using data from a mixed longitudinal data set of cleft lip and palate patients and data from the National Dutch Growth Study 1980.

Child↗

PubMed1997

Relationships between the orientation and moment arms of the human jaw muscles and normal craniofacial morphology.

It has been suggested that subjects with increased vertical craniofacial dimensions have relatively oblique orientated jaw muscles with a reduced possibility to restrain the vertical component of craniofacial growth. To test this hypothesis, relationships were investigated between the spatial orientation of the jaw muscles and the craniofacial morphology. Computer reconstructions of the external shape of the jaw muscles of 30 adult males with a normal skull were made with the use of serial magnetic resonance imaging (MRI) scans. The orientation of the jaw muscles was defined by a regression line through the centroids of the serial cross-sections. Sagittal and frontal projections of the moment arms of the muscles were measured with respect to the centre of the ipsilateral condyle. Craniofacial morphology was analysed three-dimensionally using lateral head films and coronal MRI scans. The cephalometric data were analysed statistically using regression and factor analyses. Six cephalometric factors with Eigen values higher than 1 were correlated with jaw muscle orientation and moment arm data, using a multiple regression analysis. The anterior face height factor was significantly correlated with the orientation of the jaw opening muscles in the sagittal plane but was not significantly correlated with the orientation of the mandibular elevators. The sagittal moment arms of the mandibular elevators showed significant correlations with the factors describing the gonial angle and the posterior face height. It was concluded that the variation of spatial orientation of the human jaw closing muscles is predominantly associated with the variation of mandibular morphology (expressed by the gonial angle) and the posterior face height. The orientation of the jaw opening muscles shows significant relationships with anterior vertical craniofacial dimensions. The hypothesis that persons with an increased anterior face height have relatively oblique orientated jaw elevators was rejected.

Adult↗

PubMed1997

Incidence of dental caries in the primary dentition in children with a cleft lip and/or palate.

The incidence of dental caries in the primary dentition was determined in Dutch cleft lip and/or palate children (n = 81) and in children without a congenital malformation (n = 77). In the oral cleft group the incidence of dental caries (0.037; 95% CI 0.031-0.046) was significantly higher than in the control group (0.004; 95% CI 0.002-0.007) with a crude incidence rate ratio of 9.3. Adjusted for oral hygiene, oral cleft yielded a rate ratio (relative risk) of approximately 3.5 (95% CI 1.35-9.28) in the multivariate analysis. Dental caries occurred in 25 children with an oral cleft (30.9%) and in 5 control children (6.5%). All types of teeth were affected in the oral cleft group while in the control group dental caries only occurred in maxillary incisors and second molars. The highest incidence of dental caries was found in the teeth beside the oral cleft and in the primary molars of the oral cleft group.

Case-Control Studies↗

PubMed1997

Sagittal position of the left and right maxillary segment in children with cleft lip and palate.

OBJECTIVE: The purpose of the present study was to investigate left-right differences in the sagittal position of the maxillary segments in children with cleft lip and palate. METHOD: The sample consisted of children with operated cleft lip or cleft lip and alveolus [CL/CLA (n = 16) mean age, 9.3 yr], operated unilateral cleft lip and palate [UCLP (n = 27) mean age, 9.1 yr], and operated bilateral cleft lip and palate [BCLP (n = 17) mean age, 9.5 yr]. Computed tomography (CT) horizontal slices of the maxilla were obtained and used to determine the sagittal position of the left and right segment of the maxilla in relation to the mandibular rami and the cranial base. Significant effects were analyzed with multivariate analyses of variance (MANOVA). RESULTS AND CONCLUSIONS: It was concluded that, in contrast to children having CL/CLA or UCLP, children with BCLP showed left-right differences in the sagittal position of the maxillary segments. The segment on the left side was more posteriorly positioned compared to the right side. Because the same results were obtained in relation to the mandibular rami as well as in relation to the cranial base, it can be assumed that the position of these rami are not affected by the different types of oral clefts.

Alveolar Process↗

PubMed1996

Blepharo-cheilo-dontic (BCD) syndrome.

Patients with the autosomal dominant ble-pharo-cheilo-dontic (BCD) syndrome have ectropion of lower eyelids, distichiasis of upper eyelids, euryblepharon, bilaterally cleft lip/palate, oligodontia, and conical crown form. Initially known under the eponym "Elschnig syndrome" (1912), BCD syndrome has been described in binary, ternary, and quaternary combination. There is overlap with the syndrome reported by Martínez et al. [1987], postaxial acrofacial dysostosis (Miller syndrome, Genée-Wiedemann syndrome), and a syndrome reported briefly by Warburg.

Child↗

PubMed1996

Masseter muscle thickness in growing individuals and its relation to facial morphology.

It is widely accepted that an interaction exists between masticatory muscle function and craniofacial growth. In adults, correlations have been found between facial dimensions and jaw-muscle cross-sectional area, and between facial dimensions and masseter muscle thickness. Little is known about growth of the human masticatory muscles and its relation with facial dimensions at different ages. In 329 Greek individuals, aged 7-22 yr, masseter muscle thickness was measured by ultrasonography. Muscle thickness was related to age, stature and weight, and to facial dimensions, measured by means of anthropological calipers. Muscle thickness was statistically assessed by univariate analysis of variance, after the males and females had been divided into three age groups. Facial dimensions were assessed by multivariate analysis of variance, age being considered as a covariate. The relation between muscle thickness and facial dimensions was subjected to stepwise multiple regression analysis. Masseter muscle thickness increased with age in both sexes. No differences were found between the left- and right-hand side. For each age group (and corrected for stature and weight), males had significantly thicker masseters than females (p < 0.01). Variation in muscle size and facial dimensions mainly coincided with variation in age, stature and weight. Apart from these, muscle thickness showed a significantly negative relation with anterior facial height and mandibular length, and a significantly positive relation with intergonial width and bizygomatic facial width.

Adolescent↗

PubMed1996

Quantification of facial morphology using stereophotogrammetry--demonstration of a new concept.

OBJECTIVES: The purpose of this study was to introduce stereophotogrammetry as a three-dimensional registration method for quantifying facial morphology and detecting changes in facial morphology during growth and development. METHODS: Using stereophotogrammetry, three-dimensional (3-D) co-ordinates for the bilateral landmarks Exocanthion and Cheilion and the midsagittal landmark Pronasale were determined in 10 subjects to ascertain the reproducibility of the method, and in 59 children to detect changes in facial morphology due to growth and development. Linear and angular measurements were calculated by means of the 3-D co-ordinates in order to quantify facial morphology. Significant differences were determined by means of analyses of variance (MANOVA). RESULTS: During the observation period, significant (P < 0.01) changes in facial morphology were determined for the linear measurements. Advantages and disadvantages of current registration methods are discussed. CONCLUSION: It is concluded that stereophotogrammetry is a suitable 3-D registration method for quantifying and detecting developmental changes in facial morphology.

Analysis of Variance↗

PubMed1996

Management of developmental asymmetrical facial growth.

Several aspects of the management of developmental asymmetrical facial growth are addressed. The abnormality is further defined. Methods of examination and assessment of records are discussed. A complicating factor has been the adoption of too many classification systems. With three-dimensional imaging techniques (computed tomography scan and stereophotography) great advancement has been made in efforts at describing the range of variation. Hemifacial microsomia patients are best treated in multidisciplinary centers by competent specialists with the necessary expertise and skills. The procedure followed in the craniofacial center in Rotterdam is described and discussed in relation to current treatment strategies. The success of the treatment of the asymmetrical facial growth depends on the original abnormality, on secondary abnormal development, and on orthodontic and surgical intervention. International cooperation is necessary to compile sufficient statistical data for a scientific evaluation of treatment results and to improve the effectiveness and the efficiency of treatment.

Adolescent↗

PubMed1996

The influence of transforming growth factor beta 1 on the development of embryonic mouse long bones.

Transforming growth factor beta (TGF-beta) is an important regulator of bone metabolism, and is found in large quantities in embryonic and adult bone tissue. The influence of TGF-beta 1 on chondro-osteogenesis was studied. In organ cultures of developing long bone rudiments of embryonic mice, growth and development of the various cartilaginous and osseous compartments were investigated by morphometric analysis and autoradiography after [3H]-thymidine labelling. TGF-beta 1 (1 ng/ml) inhibited both chondrogenesis and osteogenesis, and also inhibited matrix calcification. The effect was greatest in cell populations with the highest proliferation rate. It was noticed that the bone collar formation was inhibited. This may be due to an inhibition of osteoblast proliferation or differentiation, but it seems more likely to be an inhibition of the manufacture of matrix substance. These data suggest that TGF-beta 1 may be an important regulator of embryonic bone development.

Animals↗

PubMed1996

Vertical facial growth and statural growth in girls: a longitudinal comparison.

Individual and average growth patterns of the facial dimensions Nasion-Gnathion and Sella-Gonion, as related to statural growth were studied. The sample consisted of 134 girls aged 7-14 years. Data were analysed using a multivariate extension of the multilevel model for longitudinal data. The results confirmed that the mean growth curves of Nasion-Gnathion, Sella-Gonion and body height parallel each other to a large extent. At an individual level it appeared that the pubertal growth spurt of body height and the growth spurts of both facial dimensions are coincident. The major results of the present study pertain to the dynamic (age-dependent) relationship between statural growth and the growth of the face. It appears that there exists a stronger relationship between the growth velocities of standing height, Sella-Gonion and Nasion-Gnathion than between the actual lengths of the three variables themselves. The strongest relation was found between the growth velocity of body height and that of Sella-Gonion. These findings may be a contribution for diagnosis and treatment planning of individual cases.

Adolescent↗

PubMed1996

Jaw muscle orientation and moment arms of long-face and normal adults.

Long-face subjects have strongly reduced bite forces relative to normal subjects. This difference cannot be fully explained by the reduced cross-sectional area of the jaw muscles. In this study, we investigated whether the orientation and moment arms of the jaw muscles of normal and long-face subjects are different, and if so, to what extent these differences contribute to the observed differences in maximum molar bite-force levels. Three MRI scan series with different orientations were made of the jaw muscles of 30 normal and 13 long-face subjects. These served as the basis for computer reconstructions of the external shape of the muscles. The spatial orientation of the jaw muscles was defined by the regression line through the centroids of the muscular cross-sections. The moment arms of the jaw muscles and the bite point of the first mandibular molar were measured with respect to the center of the ipsilateral condyle. The muscular variables-including angles, moment arms, and mechanical advantage-were analyzed with a discriminant analysis and a multivariate analysis of variance (MANOVA). Differences in the spatial orientation of the temporalis muscle and the anterior digastric muscle contributed most to the distinction of the normal and long-face group. With MANOVA, it was shown that the normal and long-face group did not significantly differ with respect to the jaw muscle moment arms and mechanical advantage data. Only small differences were found between the sagittal muscle angles of the masseter and anterior digastric muscles in the two groups. In both the normal and long-face group, the orientation and moment arm data of the right and left muscles differed significantly. It was concluded that the variation of the spatial orientation of the jaw muscles is small and does not significantly contribute to the explanation of the different molar bite-force levels of long-face and normal subjects. Therefore, it is tempting to assume that the jaw muscles of normal and long-face subjects are different with respect to the maximum force they can exert per unit of cross-sectional area.

Adult↗

PubMed1996

Early palatal changes after initial palatal surgery in children with cleft lip and palate.

Early palatal growth and development after primary palatal closure was studied in children with different types of cleft lip and palate (CLP). Palatal dimensions were measured on dental casts taken at fixed ages, from 9 months to 4 years of age. The results showed that soft and hard palatal closure in one stage had a significant impeding influence on posterior sagittal palatal growth compared to closure of the soft palate only. Timing of surgery possibly had a small temporary restrictive effect on posterior transverse palatal growth and development. Type and severity of the oral cleft had a significant effect on transverse palatal development and anterior sagittal dimensions. Anterior arch width was reduced in children with a complete unilateral (U) CLP or bilateral (B) CLP. The palates of the latter children had consistently larger anterior arch depths. Compared to normal children, palates of cleft children changed anteriorly from wider at 9 months of age to narrower at 4 years of age. Arch depths were smaller in cleft children except for anterior arch depths in children with complete BCLP.

Age Factors↗

PubMed1996

Prediction of early palatal growth and development in children with cleft lip and palate.

With the use of multilevel modeling of longitudinal data, the relationship between the developmental status of the palate at 4 years of age and early palatal growth and development from birth to 1.5 years of age was studied. A model to predict palatal depths and widths at 4 years of age was developed and tested. The sample consisted of 130 children with cleft lip and/or palate. They were divided into three groups according to surgical treatment; (1) no palatal surgery, (2) soft palatal surgery, and (3) soft and hard palatal surgery. Results showed that in groups 1 and 2, the total arch depth at 4 years of age is strongly related to the initial arch depth at birth. No or low correlations were found between palatal depth at 4 years of age and the growth velocity at birth. The anterior arch width in groups 2 and 3 at 4 years of age appeared to be strongly related to the early growth velocity. In group 1, a moderate correlation with the palatal width and growth velocity at birth was observed. The results of the individual predictions of arch depths and arch widths were reasonable to fair. It was concluded that prediction of individual arch variables at 4 years of age is possible, although within limits. Clinically this means that extreme development can be discriminated from more average development.

Age Factors↗

PubMed1996

Prevalence of Streptococcus mutans and lactobacilli in 18-month-old children with cleft lip and/or palate.

The prevalence of Streptococcus mutans and lactobacilli was determined in 62 18-month-old Dutch children with a cleft lip and/or palate. Plaque and saliva samples were collected, a dental examination was performed, and the parents were interviewed with a structured questionnaire regarding general health, dietary habits, fluoride exposure, and socioeconomic class. Appropriate dilutions of the plaque and saliva samples were cultured on selective media to count all viable bacteria, S. mutans and lactobacilli. S. mutans was detected in the saliva of 45% of the children, and lactobacilli was detected in 16%. Also, S. mutans was detected in 48% of the plaque samples and lactobacilli in 8%. Of all of the variables examined, consumption of more than three snacks and beverages between main meals was significantly associated with presence of S. mutans in saliva. Preoperative infant orthopedic treatment (i.e., wearing an acrylic plate from shortly after birth) was significantly associated with presence of lactobacilli in saliva. The presence of S. mutans in the plaque samples was also significantly associated with presence of lactobacilli in saliva. These results indicate that children with oral cleft are at an increased risk of being infected by S. mutans and lactobacilli at a very early age. Such early colonization indicates a high risk for caries in the primary dentition.

Analysis of Variance↗

PubMed1996

[Hemifacial microsomia. A review].

Hemifacial microsomia is a congenital asymmetrical malformation of the skull and the face. As a congenital malformation of the face hemifacial microsomia is second in prevalence after cleft lip and palate disorders. Combinations and degrees of underdevelopment of craniofacial structures vary greatly. Therapy varies and depends on the different anomalies, but mostly contains orthodontic and surgical treatment to improve symmetry. It is generally accepted that children with asymmetrical facial malformations are best treated in multidisciplinary craniofacial centres.

Facial Asymmetry↗

PubMed1995

Intermittent compression stimulates cartilage mineralization.

The effects of intermittent hydrostatic compressive force (ICF; 13 kPa applied at 0.3 Hz frequency), as a substitute for moderate loading in vivo, on ossifying bone organ cultures, were evaluated by means of (histo)-morphometry. In earlier studies, biochemical tests have shown an increased 45Ca intake and an increased alkaline phosphatase activity in bone organ cultures that received ICF, suggesting that ICF promoted matrix mineralization. The purpose of this study was to examine whether an effect of ICF on mineralization can be described by means of histomorphometrical analysis. Fetal mouse metatarsal bone rudiments were cultured for 5 days in serum-free medium, with (experimental) or without (control) ICF. Linear measurements taken during culture demonstrated that the dark zone in the center of the rudiment, representing mineralized hypertrophic cartilage, became significantly longer in the group that received ICF when compared with the control group. This finding was in conformation with the former studies. Histological sections of the rudiments, stained with Goldner's trichrome method were used to study changes at the cellular level and to describe the position and relative amount of mineralizing cartilage matrix (defined as Goldner-positive matrix [GPM]). Histomorphometry demonstrated that ICF treatment significantly increased the length of the hypertrophic cartilaginous zone and enhanced the amount of GPM between the mineralizing hypertrophic chondrocytes. However, the total length of the zone containing GPM was not increased, nor was the future bone collar, consisting of a thin osteoid seam, lengthened by ICF. These data indicate that the cellular processes involved in chrondrocyte hypertrophy were accelerated by ICF, as well as the extracellular processes leading to matrix mineralization. The study supports the earlier conclusion that embryonic bone rudiments are sensitive to mechanical stimulation and that moderate loading promotes their ossification in vitro.

Analysis of Variance↗