Biomedical subjects

B Prahl-Andersen

Publications and source records attributed to B Prahl-Andersen.

At least 19 recordsLinked to original sources

PubMed1992

Bone induction by demineralized bone particles: long-term observations of the implant-connective tissue interface.

Allogeneic demineralized bone (DB) powder was applied to subcutaneous pockets and cranial defects of rats and histological, histomorphometrical, and radiological evaluation was performed one to 52 weeks after implantation. In both type of implants cartilage formation was observed after 1 week between DB particles and in former vascular channels and cervices within the particles. Foci of bone formation were observed after 2 weeks in the center of the implant. Remineralization of DB particles only occurred in close contact with the new bone tissue by which they became incorporated, indicating that remineralization of DB is a continuation of a process which has started in live bone. At all times, the interface between implant and connective tissue of the host consisted of a layer of non-remineralized DB particles embedded in fibrous connective tissue. This rim was thinner at the dura-mater-side in the cranial implants, compared with the skin-side of the same implants as well as all sides of the subcutaneous implants. The rim became thinner with time but never disappeared completely. The outer contour of the mineralized implant sometimes ran right through a DB particle. A critical concentration of bone-inducing agent leaking from DB particles seems to be necessary for bone induction. We suggest that at the interface of the implant and loose connective tissue this concentration is never reached, which results in maintenance of the rim.

Animals↗

PubMed1992

Vertical growth of the anterior face: a new approach.

The mechanism of anterior vertical facial growth was studied in normal subjects between 7 and 22 years of age. This subsample (n = 60) of participants in the Nijmegen Growth Study was representative of normal variation with respect to vertical facial proportions. A negative correlation was found between the average growth rate of the upper and lower anterior facial height in boys. Boys with a relatively large facial height exhibited a higher than average growth rate of the lower anterior facial height compared with the upper facial height. In girls a similar trend was present. The individual average growth rate of the anterior upper and lower facial height maintains or accentuates the early established facial form.

Adolescent↗

PubMed1992

Early palatal changes in complete and incomplete cleft lip and/or palate.

Early palatal development in various complete and incomplete forms of cleft lip and/or palate (CLP) was studied from birth to 3 months of age by means of dental casts. Palatal morphology (shape) and dimensions--based on reproducible reference points--were determined in a group of 128 CLP children and 68 normal children who served as controls. Substantial normal palatal growth during the first 3 months of life was observed. Round arch forms changed into oval arch forms. Growth mainly takes place in the sagittal direction (+4 mm) (transverse: +1 mm). Palates of CLP children differed significantly dependent on the type of cleft and whether the cleft was complete or incomplete. Cleft lip and alveolus children and bilateral cleft lip and palate children had more elongated palatal arches, whereas unilateral cleft lip and palate children and cleft palate children had wider palatal arches than the control group. Incomplete clefts differed from the control group in the same direction as their complete cleft forms, though less distinctly. Preoperative orthopedics used in CLP patients does not stimulate growth. On the contrary, it even restricts growth.

Cleft Lip↗

PubMed1992

A comparison of jaw muscle cross-sections of long-face and normal adults.

Long-face subjects have smaller maximum molar bite forces than do normal individuals. This has been attributed both to differences in moment arms and size of the jaw muscles. In this study, a comparison was made between the mid-belly cross-sectional areas of the jaw muscles of 13 long-face and 35 normal adults by means of serial MRI scans. The subjects were selected on the basis of anterior lower face height as a percentage of anterior total face height. These and other cephalometric variables were measured from lateral radiographs. In the long-face group, the cross-sectional areas of the masseter, medial pterygoid, and anterior temporal muscles were, respectively, 30%, 22%, and 15% smaller than in the control group. By a discriminant analysis and a multivariate analysis of variance, these differences were found to be significant (p less than 0.001). The findings of this study hint that differences in the sizes of the jaw muscles of long-face and normal subjects might explain, in part, the observed differences in maximum molar bite force.

Adult↗

PubMed1992

A six-center international study of treatment outcome in patients with clefts of the lip and palate: Part 1. Principles and study design.

This article describes the design of an intercenter comparative study of treatment outcome in the treatment of children with a unilateral complete cleft of the lip and palate. The rationale and aims of this study are defined and treatment schemes of the participating centers are described. The findings are presented in a series of three papers (Parts 2, 3, and 4) dealing with the comparison of craniofacial form, dental arch relationships, and nasolabial appearance. In Part 5, conclusions and general recommendations regarding future research are discussed.

Child↗

PubMed1992

A six-center international study of treatment outcome in patients with clefts of the lip and palate: Part 2. Craniofacial form and soft tissue profile.

The craniofacial morphology and the soft tissue profile were evaluated in this part of the intercenter study of the European Cleft Lip and Palate Research Group. The sample was comprised of cephalometric x-rays of the full cohort of 151 cases from the six European cleft palate centers. The facial morphology in complete unilateral cleft lip and palate patients was evaluated by means of roentgen cephalometry. Approximately 25 consecutive cases from each of six European cleft palate centers were compared. Only one center showed notable and consistent differences from the others. A contributing factor for these differences may be an inconsistent treatment regimen with many surgeons involved. Analysis of the soft tissue profile between the centers showed more pronounced differences than analysis of the skeletal profile. The treatment outcome in centers with more complex or expensive programs was no better than those centers using simpler management approaches.

Analysis of Variance↗

PubMed1992

A six-center international study of treatment outcome in patients with clefts of the lip and palate: Part 3. Dental arch relationships.

One hundred and forty-nine dental casts of subjects with complete unilateral clefts of the lip and palate from six European cleft palate centers were assessed by means of the Goslon Yardstick. The Yardstick proved capable of discriminating between the quality of the dental arch relationships between the six centers. Two centers showed especially poor results. Three centers obtained satisfactory results although differing surgical techniques were used in these centers. One of the centers showing satisfactory dental arch relationships employed a more complex and expensive treatment program than the other two centers, which both used simpler centralized treatment regimens.

Analysis of Variance↗

PubMed1992

A six-center international study of treatment outcome in patients with clefts of the lip and palate: Part 4. Assessment of nasolabial appearance.

One hundred and fifteen frontal and profile photographs of the nasolabial area of subjects with complete unilateral clefts of the lip and palate from six European centers were assessed. Four components of the nasolabial area were rated separately by a panel of judges using a five-point scale of attractiveness. The Tukey multiple comparison test showed significant differences between the centers. The relative position of the six centers in this study followed a similar pattern to their respective positions in the cephalometric and dental cast studies.

Child↗

PubMed1992

A six-center international study of treatment outcome in patients with clefts of the lip and palate: Part 5. General discussion and conclusions.

Part 5 is the final part of a series of five articles reporting on an international, multicenter clinical audit of treatment outcome for complete UCLP. A number of recommendations for the methodology of future studies is made especially with respect to entry criteria, sample size, assumptions of homogeneity, and the reproducibility and validity of outcome measures. The findings of the present study regarding clinical procedures are presented tentatively, and improvement and extension of the methodology are required. It appears, however, that acceptable results can be achieved by different programs and ultimately clinical choices may be based on factors such as complexity, costs, and demands of treatment. Standardization, centralization, and the participation of high volume operators were associated with good outcomes, and nonstandardization and the participation of low volume operators with poor outcomes. Therapeutic factors associated with good outcomes were the employment of a vomer flap to close the anterior palate, and poor outcomes with primary bone grafting and with active presurgical orthopedics.

Bone Transplantation↗

PubMed1992

Reproductive history of mothers of children with solitary, nonsyndromic cleft lip and/or palate.

The reproductive history was studied to evaluate if the three types of solitary, nonsyndromic clefts: cleft lip (CL), cleft lip and palate (CLP), and cleft palate (CP) are homogeneous entities. Occurrence of fetal loss, maternal health, and drug consumption of the mother during the pregnancy were compared in cases involving three types of clefts. Data was gathered from 87 children with clefts, 55 males and 32 females. Spontaneous abortions and vaginal bleeding were found to occur significantly more often in the (older) mother of a CLP child. This suggests that the factors involved in the etiology of CLP differ from the factors involved in CL and CP. Therefore, grouping of data of the three types of clefts in studies on the etiology should be avoided.

Abortion, Spontaneous↗

PubMed1992

Growth comparison between children with cleft lip and/or palate and controls.

General growth from birth to 2.5 years of age of 45 children with a solitary, nonsyndromic cleft lip and/or palate (CL/P) was compared to that of 50 controls. Weight, height, and head circumference were studied in relation to possible influencing factors. Growth of children with CL/P was found to be similar, to a large extent, to that of the control sample, with the exception of growth measured by height. Whereas males in the control group are generally taller than females, the reverse is seen for the CL/P group. Feeding difficulties and intestinal disorders, airway infections, and cleft restoring operations do not account for differences among the groups with CL/P and the control group as was suggested in the literature. Feeding difficulties and intestinal disorders between 12 and 18 months of age and airway infections between 0 and 3 months of age were identified as having a negative influence on growth, measured by weight and height, though not on head circumference.

Body Height↗

PubMed1992

Shape of the craniofacial complex in children with Turner syndrome.

The shape of the craniofacial complex was established in 69 children with Turner syndrome aged between 3.5 and 16.6 years. The children had not been treated with growth hormone (GH) or anabolic steroids. On a standardized lateral roentgenencephalogram 13 linear and 7 angular variables were measured. Data of all variables were available from normal Dutch children for comparison. The main abnormalities were located in the cranial base and in the mandible and consisted of a short posterior cranial base, all increased cranial base angle and a short, retrognathic and posteriorly rotated mandible. The maxilla was smaller than normal and also slightly posteriorly rotated. The abnormalities were already present in young children with Turner syndrome. Indications were found that in Turner syndrome interstitially as well as appositionally growing cartilage is affected. The changes in the maxilla can be explained in various ways. They may be due to defective growth of the nasal cartilage or to a disorder in the intramembranous ossification of the maxilla or they may be adaptive to the changes in the cranial base and the mandible. From this study it can be concluded that patients with Turner syndrome exhibit several craniofacial abnormalities, probably due to a cartilage disorder.

Adolescent↗

PubMed1992

Effects of lip adhesion and presurgical orthopedics on facial growth: an evaluation of four treatment protocols.

Differences in craniofacial morphology in uni and bilateral cleft lip and palate were studied by roentgenocephalometry: 35 American children, treated with a lip adhesion procedure, and 26 Dutch children treated with a preoperative orthopedic procedure, both followed by a lip and/or palatal repair, were compared. A multivariate statistical approach was used to study the effects of the surgical procedures and of the age of the child when operated upon. The variables affected by the type of operation were: the relative length of the maxilla (PNS-ANS); the SNA angle; and the relative length of the mandible (Go-Po). The length of the maxilla was on average longer for those treated with preoperative orthopedics and the maxilla was largest for children whose hard palate had yet to be closed. This was also the case for the SNA angle except for children treated with the combined lip-soft palate closure procedure. The mandible followed pattern displayed by the maxillary length; it was larger for those treated with preoperative orthopedics. Significant effects of the timing of the surgery on the variables studied were also found. Postponement of the definitive lip closure resulted in a reduction of the maxillary length, whereas delay of soft palatal closure resulted in an increase of the maxillary length.

Activator Appliances↗

PubMed1991

Vertical facial growth: a longitudinal study from 7 to 14 years of age.

Multilevel analysis is used to describe the changes in vertical facial dimensions and their relationships in Dutch girls between 7 and 14 years of age. For the anterior face height (nasion-gnathion) and the posterior face height (sella-gonion) a fourth degree polynomial was fitted. The mandibular plane angle (sella nasion-gonion gnathion) could be described with a second degree polynomial. Low correlations were found between the growth parameters (intercept and age coefficient) of the anterior and posterior face height, which points to independent growth and development of the anterior and posterior face height. The individual length and growth velocity (at age 10.8) of the anterior face height and the mandibular plane angle showed substantial correlations. It was concluded that changes during growth with regard to the mandibular plane angle are more strongly related to the anterior than to the posterior face height.

Adolescent↗

PubMed1991

Relationships between jaw muscle cross-sections and craniofacial morphology in normal adults, studied with magnetic resonance imaging.

In 32 Caucasian adult males serial MRI scans of the jaw muscles were taken approximately perpendicular to the mean fibre direction of the jaw muscles to determine their cross-sectional areas. These areas are proportional to the maximal isometric strength of a muscle. To describe facial skeletal variation, nine angular and 21 linear cephalometric measurements were recorded, and statistically reduced by means of multiple regression and principal component analysis. Six components were extracted, rotated, and subsequently correlated with the maximal cross-sectional areas of the jaw elevators and anterior digastric muscle. Positive significant correlations were found between a linear combination of several transversal skull dimensions on the one hand, and the maximal temporalis and masseter cross-sections on the other. A negative significant correlation was found between the flexure of the cranial base and the temporalis cross-section. Surprisingly, no significant correlations were found between either anterior facial height or posterior facial height and any of the jaw muscles cross-sections. It was concluded that, in adult males with normal skull shape, relationships exist to a limited extent between craniofacial morphology and the cross-sectional areas of the jaw muscles.

Adult↗

PubMed1991

A new method for locating anterior skeletal landmarks from soft tissue measurements.

Clinical examination of human profiles provides some idea of the localization of hard tissue landmarks, but is unreliable because of large variability in thickness of the soft tissues. In this investigation an instrument was developed to measure the thickness of the lips. Linear regression was applied to estimate cephalometric hard tissue landmarks from those in the soft tissues. By adding information from direct clinical measurements to the model for estimating hard tissue landmarks from soft tissue landmarks, the correlation between the digitized (actual) and estimated or calculated landmarks was significantly improved.

Adult↗

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↗