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Biomedical subjects

B Prahl-Andersen

Publications and source records attributed to B Prahl-Andersen.

At least 109 records · Page 6Linked to original sources
PubMed1990

The effect of duration and magnitude of tensile mechanical forces on sutural tissue in vivo.

Orthodontic springs were placed across the interparietal suture in twenty 30-day-old male Wistar rats, in order to study the effect of tensile forces on the initial biological response of sutural tissues. Five groups of different force duration and magnitude were used: a 6 hours (h), 0 mN group; 6 h and 24 h, 50 mN groups; and 6 h and 24 h, 100 mN groups. One group of four animals served as a control. The animals were injected with tritiated proline 3 hours prior to the end of the experiment. Undecalcified 5 microns sections were used for (enzyme) histology and autoradiography in order to quantify several morphometric variables. The data were analysed with multivariate analysis of variance and contrast calculations. Application of the springs led to significant sutural widening within 6 hours. The concentration of fibroblasts in the suture also increased significantly within 6 hours. The volume of the suture and the incorporation of 3H-proline in the fibrous part of the suture and in the osteoid along the sutural bony edges were significantly increased after 24 hours of force. In general, force duration had a greater impact on histological events than force magnitude.

Acid Phosphatase↗
PubMed1989

Emergence of the deciduous incisors in CLP children.

A longitudinal study of the time of emergence of the deciduous incisors was performed in Dutch cleft lip and/or palate (CLP) children (n = 52). A group of normal children (n = 62) served as control. Emergence dates were registered by the parents and checked regularly by one of the investigators. Mean emergence times of the deciduous upper incisors--including both the cleft-sided lateral in the distal segment and in the premaxilla--and lower incisors were studied. The lateral incisor on the cleft side situated in the distal segment was delayed 8 months in children with a cleft lip and alveolus and 13 months in cleft lip and palate children. The delay for the lateral incisor situated in the premaxilla increased by nearly 4 months in these children. The upper lateral incisors on the non-cleft side and in cleft palate children were not delayed as compared with normal children. The central lower incisors emerged one month earlier than normal when there was a palatal cleft. Presurgical orthopaedics used in these groups could have caused this acceleration. The central upper and lateral lower incisors showed no significant differences in mean emergence ages as compared with the control group, nor between the various cleft types. Sex differences were not found in any of the groups.

Age Factors↗
PubMed1989

Comparison of jaw-muscle bite-force cross-sections obtained by means of magnetic resonance imaging and high-resolution CT scanning.

Cross-sectional areas of the jaw muscles were determined by means of magnetic resonance imaging (MRI) in 12 healthy adult male subjects. These findings were compared with the cross-sectional areas of the jaw muscles of the same subjects, obtained by means of computer tomography (CT) in a previous study (Weijs and Hillen, 1985). Significant correlations (r greater than 0.7) were found between the CT and MRI cross-sections of the masseter, medial pterygoid, and temporalis muscles. The low correlation between the CT and MRI cross-sections of the lateral pterygoid muscle could be explained by the different imaging techniques (slice thickness) of MRI and CT scanning. CT and MRI cross-sectional areas of the masseter and medial pterygoid muscle (but not the temporalis muscle) showed highly positive and significant correlations with the maximal voluntary bite force. In living subjects, the cross-sections of the masseter and medial pterygoid muscles can be visualized with CT and MRI. Compared with CT, MRI has some advantages, such as the absence of adverse effects (no radiation) and the excellent soft-tissue imaging. Furthermore, a series of frontal, horizontal, sagittal, and angulated MRI scans can be made without modification of the patient's position, facilitating reconstruction of the jaw muscles.

Adult↗
PubMed1988

Dental anomalies in patients with familial and sporadic cleft lip and palate.

Based on the frequency of occurrence of cleft lip and palate (CLP) in a family, a distinction has been made between familial and sporadic CLP. It was presumed that the genetic predisposition in familial CLP is high, while in sporadic CLP environmental factors play an important role. This study describes the possible relationship between the incidence of dental anomalies and the genetic predisposition of CLP in both the deciduous and permanent dentition. Dental anomalies were studied in 100 CLP patients and 38 control subjects. Neither the number of dental anomalies, nor the numbers of missing and supernumerary teeth differed significantly between familial and sporadic cases. A comparison between subjects with and without CLP showed a significant difference in the morphology of the dentition of the upper jaw. This difference was quantitative rather than qualitative. This study indicates a direct relationship between cleft formation and formation of the teeth, irrespective of the genetic predisposition and the severity of the cleft (i.e. uni- or bilateral).

Anodontia↗
PubMed1987

Development and use of shell-less quail chorio-allantoic-membrane cultures to study developing skeletal tissues; a qualitative study.

A technique is described for in vitro culture of the quail embryo from the 1st to the 18th day of development. The embryos are cultured in Teflon hammocks, suspended in glass supports and kept in a humidified atmosphere at 36.5 degrees C. The quail CAM is used as support and cell source for developing non-quail cartilage and bone. The quail cells can be identified histologically and easily recognized by Feulgen-staining which is demonstrated in the presence of quail chondro- or osteoclasts in a mouse long bone rudiment cultured on the CAM.

Allantois↗
PubMed1987

The growth of cartilage cells in vitro and the effect of intermittent compressive force. A histological evaluation.

Chick epiphyseal chondrocytes are isolated from 15 day old embryos and subsequently grown as small high density cultures (aggregates consisting of 2 X 10(5) cells), which can be handled individually. Histological evaluation showed a considerable increase in the dimensions of the nucleus and the cells 2-6 hours after initiating the growth of the chondrocytes by adding 10% serum to the culture medium. After 24 hours of culture the proportion of the matrix in the aggregate was increased from 0% to about 45%. In a series of experiments these aggregates were exposed to intermittent compressive force (ICF) with a peak value of 130 mbar above ambient and a frequency of 0.3 Hz. The nuclear and cell-dimensions of ICF-exposed chondrocytes were significantly larger than under control conditions when measured after 24 and 48 hours. Concomitantly, chondrocytes in ICF-exposed aggregates synthesized and deposited significantly more matrix in the aggregates as compared to controls. This model can be used to further study the direct effect of mechanical force on the synthesis and deposition of matrix components by cartilage cells in vitro.

Animals↗
PubMed1986

[Incidence of cheilognathopalatoschisis in the Netherlands].

Until now, data on the incidence of cleft lip and/or palate in the Netherlands are scarcely available. For this study data were used from the National Medical Registration (NMR) and the National Obstetric Registration (NOR) over the years 1982 and 1983. Only children born in a general hospital have been registered. In the years 1982 and 1983 the NMR registered 295 children with the malformation just mentioned. The incidence calculated from these figures is between 1,38 and 1,77. The age distribution of mothers with a child with a cleft lip and/or palate (CLP) was compared to the total group of mothers. No correlations were found between the age of the mother and the birth of a CLP-child. The necessity of an accurate registration of congenital malformations in general in the Netherlands is emphasized.

Adult↗
PubMed1979

Perceptions of dentofacial morphology by laypersons, general dentists, and orthodontists.

Line drawings of facial profiles and color photographs of dentitions were evaluated subjectively by 1,150 parents, 72 general practictioners of dentistry, and 54 orthodontists with regard to the normality and abnormality in dentofacial morphology and the need for orthodontic treatment. A significant difference was found between the evaluations of the parents and the professional groups in ten of the 11 facial profiles and in seven of the 11 photographs of dentitions. In general, the parents considered more of the examples acceptable and not requiring orthodontic treatment than did the professional groups. The dentists and orthodontists deviated significantly in their ratings onjy in their judgement of "ugly duckling" example (picture 22, higher abnormal rating by the dentists) and the profile example 10 (higher abnormal rating by orthodontists). number of orthondontists may have associated the conditions in picture 10 with a Class II, Division 2 malocclusion and, as such, scored it abnormal.

Child↗
PubMed1979

[Biological age in children with clefts].

The skeletal and the dental maturity in a group of 189 children with cleft lip and/or cleft palate were determined by means of X-rays of the wrist joint and orthopantomogrammes. In 60 children, anthropometric determinations were also performed. 486 normal children involved in the Nijmegen growth study served as control subjects. The ages ranged from 4 to 14 years. A retardation in dental development was evidenced in boys with clefts. There was no remarkable difference in dental development between girls with clefts and girls without clefts. The progression in skeletal maturity was greater in girls with clefts than in girls without clefts. There was no remarkable difference in skeletal maturity between boys with clefts and normal boys. The determination of 10 anthropometric values revealed only a few remarkable differences between children with clefts and normal children.

Adolescent↗