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Biomedical subjects

B Prahl-Andersen

Publications and source records attributed to B Prahl-Andersen.

At least 73 records · Page 4Linked to original sources
PubMed1995

Longitudinal analysis of radiographic trabecular pattern by image processing.

To describe structural and textural changes in bone structure, the radiographic trabecular pattern of children, aged 4-14 years, was examined using a digital image processing system. This investigation is based on data from the Nijmegen Growth Study, a mixed-longitudinal growth study comprised of three birth cohorts, which were observed for five years. Of 3075 left hand-forearm radiographs of 426 children, a standard area of 10 x 10 mm of the radius was digitized and the trabecular pattern was described by ten image features. It is demonstrated that all image features show significant changes during the observation period (multivariate analysis of variance of p < 0.01). The age of the children correlates significantly with the image features (Spearman's Rho = 0.4; p < 0.05). Because of cohort effects, the three cohorts were studied separately. Highest correlations between age and trabecular pattern were shown in the cohort of the youngest children. The changes of the image features during the observation period seems to indicate that the fine trabecular pattern of young children changes into a coarser adult pattern. It is concluded that digital quantification of the radiographic trabecular pattern is appropriate to describe changes in trabecular bone.

Adolescent↗
PubMed1995

Adolescent growth changes in soft tissue profile.

Growth of the lips, nose and chin was studied in a mixed longitudinal sample of 82 subjects from the "Nijmegen Growth Study". The age range was between 9 and 14 years with a single measurement at the age of 22 years. Differences in growth pattern between boys and girls are illustrated by mean cumulative growth curves and mean growth velocity curves as well as by contour plots.

Adolescent↗
PubMed1995

Method for quantifying facial asymmetry in three dimensions using stereophotogrammetry.

A three-dimensional method to quantify facial asymmetry is introduced. Stereophotogrammetry was applied to determine three-dimensional (3-D) coordinates for eight pairs of surface landmarks of 106 individuals, including 16 with an operated complete unilateral cleft lip and palate. Facial asymmetry was quantified from four different reference planes that were defined perpendicular to and bisecting lines between pairs of bilateral landmarks related to the eyes, nose and mouth. Significant differences (P < 0.01) between these four planes were determined using multivariate analyses of variance (MANOVA). It is concluded that the best reference plane to select in studies of facial asymmetry is formed by the one which is perpendicular to and bisects the line that connects the landmarks Exocanthion. Reproducibility and validity of the method is demonstrated.

Child↗
PubMed1995

Longitudinal study on three-dimensional changes of facial asymmetry in children between 4 to 12 years of age with unilateral cleft lip and palate.

The purpose of the present study was to describe three-dimensional developmental changes of facial asymmetry in children with an operated complete unilateral cleft lip and palate (UCLP) and in children without craniofacial anomalies (controls). Using stereophotogrammetry, three-dimensional coordinates for 16 bilateral and 10 midsagittal facial landmarks were determined for the UCLP group (n = 33) and the control group (n = 63) on two occasions. In this mixed-longitudinal study, the children were 4 to 12 years of age. Facial asymmetry and left-right dominance was measured and resolved for transverse, vertical, and sagittal components. Significant effects were analyzed with multivariate analyses of variance (MANOVA). We concluded that individuals with complete unilateral cleft lip and palate, as well as individuals without craniofacial anomalies, show an increase, during growth, in the amount of facial asymmetry in the basal region of the nose. In the region that is related to the cleft, children with complete unilateral cleft lip and palate do not show changes in the amount of facial asymmetry between the occasions. Regarding facial left-right dominance and variation in dominance, no demonstrable growth changes take place in individuals with complete cleft lip and palate, nor in individuals without craniofacial anomalies.

Case-Control Studies↗
PubMed1994

A comparison of human masseter muscle thickness measured by ultrasonography and magnetic resonance imaging.

Non-invasive imaging techniques such as computerized tomography, magnetic resonance imaging (MRI), and ultrasonography enable measurements of the cross-section and thickness of human jaw muscles in vivo, providing an indication of the maximal force a muscle can exert. In 15 adult Caucasian men the thickness of the masseter muscle was registered bilaterally on three different levels by ultrasonography. Scans were made on the contracted and relaxed muscle. A comparison was then made with measurements from serial MRI scans, using univariate analysis of variance for repeated measurements and Pearson's correlation coefficients. Variances of the repeated measurements were calculated for the different scanning levels and the different muscle conditions and tested for homogeneity. For both the ultrasound and MRI measurements there was no difference in thickness between the left and right muscle. The registration level with highest reproducibility was halfway between the origin and insertion. Measurements from the contracted muscle were more reproducible than those from the relaxed muscle. The relaxed muscle thickness measured by ultrasonography was smaller than that measured by MRI. The correlation between ultrasound and MRI was significant for the upper and middle level of scanning (p < 0.001). The highest correlation was found between MRI (relaxed) and ultrasound (contracted) at the middle level (R = 0.83, p < 10(-6)). The conclusion is that ultrasonography is an accurate and reproducible method for measuring the thickness of the masseter in vivo. It allows for large-scale longitudinal study of changes in jaw-muscle thickness during growth in relation to change in biomechanical properties of masticatory muscles.

Adult↗
PubMed1994

Cranial base growth for Dutch boys and girls: a multilevel approach.

Growth of the cranial base in Dutch children who had undergone orthodontic treatment and children who had not is described and compared with the aid of multilevel statistical techniques. Growth changes of the cranial base (S-N, N-Ba, and S-Ba) were evaluated. The results pertain to a mixed longitudinal sample of 153 boys and 167 girls for S-N and 116 boys and 116 girls for N-Ba and S-Ba, 7 to 14 years of age. No significant difference could be demonstrated between subjects who had received orthodontic treatment and subjects who had not. The cranial base displayed sexual dimorphism in the timing and amount of growth. All dimensions measured in girls were significantly smaller than in boys (p < 0.05). No adolescent growth spurts were found in girls; boys showed adolescent growth spurts for S-N and N-Ba. Adolescent growth velocities were significantly greater for boys than for girls.

Adolescent↗
PubMed1994

Computed tomography in evaluation of early secondary bone grafting.

Computed tomography (CT) was used to determine the fate of the bone graft in cleft lip and palate patients. Eight right-sided unilateral cleft lip and palate patients from the Free University Hospital in Amsterdam, treated with early, secondary bone grafting, were evaluated immediately after the operation and 1 year postoperatively. Approximately 70% of the volume of transplanted iliac crest bone was still present in the cleft area after 1 year.

Bone Resorption↗
PubMed1994

Three-dimensional evaluation of facial asymmetry in cleft lip and palate.

The purpose of the present study was to describe facial asymmetry in three dimensions in individuals with an operated complete unilateral cleft lip and palate (UCLP) and in individuals without craniofacial anomalies (controls). Three-dimensional coordinates for 16 bilateral and 10 midsagittal facial landmarks were determined for the UCLP group (N = 49) and the control group (N = 80) by means of stereophotogrammetry. The total asymmetry was measured and resolved for transverse, vertical, and sagittal components. It can be concluded that all three components are important in studies on facial asymmetry. Individuals with UCLP show more facial asymmetry in the vertical direction than controls. They demonstrate more facial asymmetry in the region related to the cleft than controls. And, males in general demonstrate more asymmetry of the nose than females.

Cephalometry↗
PubMed1994

Palatal changes after lip surgery in different types of cleft lip and palate.

This study concerns palatal development during 6 months following primary lip closure. The sample consisted of 75 children with different forms of cleft lip and palate and 51 noncleft children. The palate was measured at 3 months of age, just before lip surgery, after surgery at 6 months, and again at 9 months of age. The results showed that lip closure has a strong effect in the anterior alveolar region. This effect was restricted to 3 months after surgery. The changes in complete clefts were more explicit than in incomplete cleft forms. Furthermore, the data showed that arch depth reduction due to lip surgery was compensated for by continued anteroposterior palatal growth. Early orthopedics appeared to prevent major palatal collapse immediately after lip surgery. Finally simultaneous closure of the alveolar cleft at the nasal side resulted in continued reduction of anterior cleft width.

Case-Control Studies↗
PubMed1994

Facial left-right dominance in cleft lip and palate: three-dimension evaluation.

Studies on facial left-right dominance in individuals without craniofacial anomalies have demonstrated controversial results. This is probably due to the frequent use of two-dimensional methods, yet left-right dominance consists of transverse, vertical, and sagittal components. The aim of the present study was to describe three-dimensionally facial left-right dominance in individuals with an operated complete unilateral cleft lip and palate on the left side (LUCLP), on the right side (RUCLP), and in individuals without craniofacial anomalies (controls). Using stereophotogrammetry, three-dimensional coordinates for 16 bilateral and 10 midsagittal facial landmarks were determined for the LUCLP group (N = 32), the RUCLP group (N = 17), and the control group (N = 80). Left-right dominance was measured in three directions. Individuals without craniofacial anomalies showed a facial left sided dominance in the transverse direction, a facial right sided dominance in the sagittal direction, and no particular dominated side in the vertical direction. Individuals with a unilateral cleft lip and palate demonstrated a facial dominance of the nonaffected side in the vertical direction as well as in the sagittal direction, with no particular side dominant in the transverse direction. Generally, there was more variation in left-right dominance within the face in the vertical and sagittal directions.

Cephalometry↗
PubMed1994

[Tooth development in children with cleft lip and palate. An international inquiry into unilateral cleft lip, jaw and palate].

In a cross-sectional study of 106 European children with unilateral complete cleft lip, alveolus and palate ranging from 10 to 15 years of age, dental maturity was determined using orthopantomograms. The method and standards (the 50th percentile line) of Demirjian were used. The study shows a significant delay of dental maturity in both male and female cleft-affected patients. This delay in tooth development supports Van Limborgh's theory that the origin of clefts is due to the delayed growth and development of parts of the dentofacial area.

Adolescent↗
PubMed1994

An analysis of the orientation of the radiographic trabecular pattern in the distal radius of children.

A digital image processing system was used to study changes in orientation of the radiographic trabecular pattern of bone in children aged 4-14 years. The radiographs originated from a mixed-longitudinal growth study (The Nijmegen Growth Study), which comprised of three birth cohorts and which was carried out between 1971 and 1975. Of 3075 left hand-forearm radiographs of 426 children, the orientation of the trabecular pattern of the radius was analysed in twelve directions on a standard area of 10 x 10 millimetres. It was demonstrated that the trabecular pattern of the radius shows two predominant directions of orientation: along and perpendicular to the long axis of the radius. Spearman's Rank Correlations were calculated between direction of orientation and age of the children for the total population as well as for the cohorts separately, because the existence of cohorts-effects. The cohort of the youngest children showed more and higher significant correlations than the other cohorts, indicating that the trabecular pattern of young children is more subjected to changes. The results indicate that the prevalence of trabeculae orientated perpendicular to the long axis of the radius decreases. We speculate that this development reflects the effects of changes in mechanical loading in that direction during growth and development resulting in functional adaptation of the trabecular bone.

Adaptation, Biological↗
PubMed1994

Longitudinal changes in the orientation of trabecular bone in relation to the location in the distal radius.

The aim of this study was to examine changes in orientation of trabecular bone during growth and development in relation to the location of trabeculae between the epiphysial growth plate and the marrow cavity. Five annual hand-wrist radiographs of 57 children between 4-9 years of age, originating from the Nijmegen Growth Study, were analysed by a digital image processing system. Analysis was carried out on four adjacent areas of 7 mm x 7 mm located in the distal head of the radius between the epiphyseal growthplate and the marrow cavity. The orientation of the trabecular pattern was measured in twelve directions. The orientation of trabeculae at a standardized distance from the epiphysial growth plate did not change significantly during growth and development. The orientation in directions perpendicular to the long axis of the radius was higher in newly formed trabecular bone, which is located just below the epiphysial growthplate, than in older trabecular bone at a larger distance from the epiphysial growth plate. Observation of one single area during five years of growth and development showed a comparable development.

Aging↗
PubMed1993

Tooth formation in patients with oligodontia.

Oligodontia is defined as the congenital absence of many teeth. The aim of the present study was to evaluate tooth formation in patients with oligodontia who were missing six or more teeth. The oligodontia sample was compared to a control group matched for race, sex and age. Calcification stages of the teeth of the left side of the mandible were rated. Patients with oligodontia showed a tendency for delayed tooth formation. Significant differences in tooth formation were found between males with oligodontia and the control group for several stages of tooth formation. In females only stage 5 of the second mandibular molar showed a significant difference. Because of the great individual variation in tooth formation in patients with oligodontia, tooth formation in patients with oligodontia should be individually examined before starting treatment.

Adolescent↗
PubMed1993

Emergence of the deciduous canines and molars in CLP children.

The emergence of the deciduous canines and molars was investigated as part of a longitudinal study into the emergence of the deciduous dentition in Dutch cleft lip and/or palate children (CLP) (Kramer et al., 1989). The study comprised a group of 71 CLP children and 74 normal children that served as a control. Mean emergence ages of the deciduous upper and lower canines and molars were studied. Emergence of the deciduous primary molar on the cleft side was delayed 2 months in the upper jaw and 1 month in the lower jaw in children with an unilateral cleft lip and palate. The deciduous primary molar on the non-cleft side was not delayed as compared with normal children. Local anatomical relationships could be a possible explanation for these findings. The deciduous canines and secondary molars in both jaws showed no significant differences in mean emergence ages as compared with the control group, nor between the different cleft types. No sex differences were found in any of the groups. A table is presented containing the mean emergence ages of all the teeth of the deciduous dentition for the various CLP-groups, divided in cleft and non-cleft side, and the control group.

Analysis of Variance↗
PubMed1993

Effect of growth hormone treatment on craniofacial growth in Turner's syndrome.

A cephalometric study was performed in 19 patients with Turner's syndrome, aged 8.7-16.5 years. A lateral roentgen-encephalogram was taken before and after two years of treatment with biosynthetic growth hormone in a dose of 24 IU/m2/week. During two years of growth hormone treatment, the mandibular length increased mainly due to vertical growth. The initially posteriorly rotated mandible showed an anterior rotation, although the normal position was not reached. The other linear measurements and angles did not change during treatment. No indications were found for an increase in the disproportionate growth or for excessive chin growth as a sign of acromegaly during growth hormone treatment. In conclusion, growth hormone treatment in patients with Turner's syndrome resulted in an increase in mandibular length, mainly due to vertical growth of the ramus and in the anterior rotation of the mandible.

Acromegaly↗
PubMed1993

A multicentre comparison of treatment regimens for unilateral cleft lip and palate using a multiple regression model.

The European Cleft Lip and Palate Research Group consists of specialists in orthodontics from six centres for the treatment of cleft palate in northern Europe. The purpose of this part of the multicentre study was to investigate whether differences in outcomes could be explained by specific treatment regimens. Three regimens that were assumed to influence the outcome of treatment were selected: Presurgical orthopaedics, closure of the palate, and primary bone grafting. The sample comprised 151 children with complete unilateral cleft lip and palate from the six centres. The result of multiple regression analysis showed that within that sample it was not possible to reach definite conclusions as to which factors exerted the most favourable influence on facial growth, but primary bone grafting was associated with reduced maxillary inclination and presurgical orthopedics with increased mandibular inclination.

Bone Transplantation↗