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Biomedical subjects

I Kjaer

Publications and source records attributed to I Kjaer.

At least 73 records · Page 4Linked to original sources
PubMed1996

Ocular findings and sphenoid bone morphology in tuberous sclerosis.

The aim of the study was to focus on the correlation between the ocular findings and the morphology of the sphenoid bone supporting the optic nerve in patients with tuberous sclerosis. Ten patients participated in the investigation. The sphenoid bone morphology was analyzed from existing radiographs of the cranium. The results were compared to the individual ophthalmologic diagnosis. Changes in the midline osseous structure, the sella turcica and optic sulcus seem to be correlated with the severity of the ocular findings.

Adolescent↗
PubMed1996

The human vomeronasal organ: prenatal developmental stages and distribution of luteinizing hormone-releasing hormone.

The purpose of this study was to describe in 49 normal human prenatal specimens, 15-156 mm crown-rump length (CRL), the histomorphological development of the bilateral vomeronasal organ localized in the mucosa of the nasal septum. In addition, immunohistochemical localization of luteinizing hormone-releasing hormone (LHRH) was undertaken. The material was classified into five developmental stages (NAS I/V), based on the morphology of the nasal cavity. The vomeronasal organ was visible in stages NAS II, III and IV, corresponding to 21-102 mm CRL. Positive immunohistochemical reaction for LHRH neurons was pronounced in the vomeronasal organ in NAS II and III, corresponding approximately to fetal ages 8-12 gestational weeks (21-51 mm CRL). The study demonstrates in normal human prenatal material that LHRH can be recorded in the bilateral vomeronasal organs during approximately 4 weeks of intrauterine life.

Crown-Rump Length↗
PubMed1996

Luteinizing hormone-releasing hormone and innervation pathways in human prenatal nasal submucosa: factors of importance in evaluating Kallmann's syndrome.

A previous study has demonstrated that luteinizing hormone-releasing hormone (LHRH) is localized in the human bilateral vomeronasal organs in the nasal septum during a 4-week period of intrauterine life (22). The purpose of the present study was to elucidate the location of LHRH-expressing cells outside the vomeronasal organs, with special emphasis on the submucosa of the medial wall and roof of the nasal cavity. An additional aim was to study the innervation pathways in the same regions. Both regions can be affected in Kallmann's syndrome, which is characterized by hypogonadotropic hypogonadism (lack of LHRH) and often associated with anosmia. Histological sections of craniofacial regions (49 normal human fetuses, 6-19 weeks) were examined by immunohistochemical techniques for LHRH and for neuronal tissue (protein gene product 9.5, PGP 9.5). LHRH reactions were only seen in the septal submucosa extending from the vomeronasal organs to the olfactory bulb. There was a close spatiotemporal association between the occurrence of LHRH and neuronal tissue. From the rhino-olfactory epithelium separate nerve tissue extended to the olfactory bulb. It is suggested that the medial region of the nasal placode giving rise to the septal wall is always affected in Kallmann's syndrome, and in cases in which the phenotypic features are associated with anosmia, also the more lateral part of the nasal placode, from which the rhino-olfactory region originates, is affected.

Cell Movement↗
PubMed1996

The human mandibular canal arises from three separate canals innervating different tooth groups.

The purpose of this study was to describe the prenatal formation of the human mandibular canal. Since bony canals develop in prenatal life around the nerve paths, it was assumed that the canal pattern could reflect the pattern of innervation of the dentition. Mapping of this early canal pattern does not appear to have been undertaken before. The material consisted of anthropological mandibles from the National Institute of Anthropology and History, Mexico City. A total of 302 human hemimandibles from the latter half of the prenatal period was investigated. The length, measured from the mental symphysis to the mandibular condyle, ranged from 28 to 60 mm. The dento-alveolar maturity was classified in two stages according to the appearance of alveolar sockets of deciduous and first permanent molars. The mandibles were radiographed with guttapercha points inserted into the canal openings (foramina) on the lingual surfaces of the mandibular rami. The study showed that the canal to the incisors appeared first, followed by the canal to the primary molars, and last by the one or more canals to the first permanent molars. In the most mature group, three different canals always occurred in each hemimandible. The canals were directed from the lingual surface of the mandibular ramus toward the different tooth groups. The inferior alveolar nerve presumably occurs in the mandible as three individual nerve paths originating at different stages of development. It is suggested that rapid prenatal growth and remodeling in the ramus region result in a gradual coalescence of the canal entrances that is obvious at birth. It is hypothesized that the pattern of tooth agenesis within the three groups of teeth is related to the three separate paths of innervation of the dentition.

Dentition↗
PubMed1995

Tooth agenesis in Down syndrome.

We studied the frequency and pattern of tooth agenesis in a Danish population with Down syndrome, trisomy 21 (46 females and 54 males). The control group consisted of a normal Danish population (2424 females and 2431 males) [Rølling, 1980: Scand J Dent Res 88:365-369; Ravn and Nielsen, 1973: Tandlaaegebladet 77:12-22]. We found that individuals with Down syndrome have an occurrence of agenesis that is some 10 times greater that in the general population with a higher frequency in males than in females. Agenesis occurred more frequently in the mandible than in the maxilla and most often on the left side. The highly significant differences were primarily found in the occurrence of agenesis of the mandibular central incisors, followed by the maxillary lateral incisors and second premolars and the mandibular second premolars. The main components in the pattern of agenesis observed in Down syndrome are supposed to be related to the peripheral nervous system and abnormal cartilagenous tissue. The present study on Down syndrome suggests that the dentition, with its many different anomalies, from agenesis to malformation, can be used as an indicator in evaluating different aspects in the patheogenetic of aneuploidy conditions.

Adolescent↗
PubMed1995

Etiologic aspects and orthodontic treatment of unilateral localized arrested tooth-development combined with hearing loss.

In this study a case has been presented involving localized, arrested maxillary tooth development, asymmetric maxillary development, and unilateral loss of hearing. No similar case seems to have been described before. The orthodontic treatment comprised extraction of four permanent tooth germs in the maxilla and autotransplantation of mandibular teeth, followed by the use of fixed orthodontic appliances and a one-unit bridge restoration. Etiologic aspects are discussed. It is suggested that a severe attack of mumps that involved massive swelling of the parotid glands immediately after chicken pox and measles at the age of 4 to 5 years, may have resulted in a neurologic reduction of hearing and arrested tooth development. The teeth in which root development in relation to mumps does not appear to have been reported previously, whereas hearing loss after mumps has been reported. In the search for verification of this possible connection, children with arrested tooth development should be examined for reduction of hearing, and children with hearing loss after mumps ought to have their dental development checked.

Bicuspid↗
PubMed1995

Morphological characteristics of dentitions developing excessive root resorption during orthodontic treatment.

The present study focuses on orthodontically provoked, excessive root resorption. The purpose was to identify in these cases common morphological features in radiographic diagnostic material taken before treatment. The material was submitted by 35 Danish orthodontists. The goal was to improve the future orthodontic diagnostics of the dentition in order to prevent severe root resorption during treatment. The study indicates that: (1) there is a strong connection between various dental morphological characteristics, such as invagination, length of root, and root shapes, especially taurodontism, and the tendency to root resorption during orthodontic treatment; (2) there is a connection between anomalies in the dentition, particularly ectopia and agenesis, and the tendency to root resorption during orthodontic treatment; (3) there seems to be a connection between the pattern of resorption in the primary dentition and the tendency to root resorption in the permanent dentition following orthodontic treatment; (4) girls are more susceptible to root resorption during orthodontic treatment than boys; (5) one ought to be on the lookout for connections between condylar changes, root resorptions, and anterior open bites in connection with orthodontic treatment. The observation regarding root resorption in dentitions in which invaginations and taurodontic root shapes occur has not previously been reported. Also, the findings of deviant resorption patterns in both the primary and permanent dentitions in a considerable number of patients are new observations, which ought to be incorporated into orthodontic treatment planning.

Adolescent↗
PubMed1995

Agenesis of permanent incisors in a mediaeval maxilla and mandible: aetiological aspects.

A paleopathological maxilla and mandible with tooth agenesis were analyzed, focussing on the aetiology of the condition. The jaw material, derived from an adult mediaeval male, was examined by standard anthropological analyses, including radiography. In the maxilla there was agenesis of three permanent incisors and one premolar, and in the mandible of one permanent incisor and two permanent molars. Absence or marked reduction of the incisive foramen and the nasopalatine canal was found. The premaxillary area was reduced without general alveolar bone resorption. The pattern of tooth agenesis was similar to the pattern observed in contemporary individuals, except for the agenesis of one permanent maxillary central incisor. It is suggested that the pronounced lack of teeth in the maxillary anterior region is connected with deficient development of the premaxillary area of the nasopalatine canals and the incisive foramen. As the condition can be ascribed to deviations in the prenatal development, this investigation shows that embryological developmental patterns, which form the basis for the pattern of tooth agenesis, should be taken into account when evaluating dry bone pathology.

Anodontia↗
PubMed1995

Cranial base in newborns with complete cleft lip and palate: radiographic study.

In a 1993 study, Mølsted and colleagues found an increased width of the spheno-occipital synchondrosis in newborns with complete clefts of the lip, alveolus, and palate compared with newborns with incomplete clefts. As the spheno-occipital synchondrosis represents remnants of the early chondrocranium that later ossifies and incorporates in the cranial base, it is possible that an inborn alteration, such as a deviant growth of cartilage, or a delayed maturation in the early development of the cartilaginous cranial base, can affect not only the length and the width of the cranial base, but also the petrous portion of the temporal bone and the nasal septum, as these structures also have a cartilaginous origin. The purpose of the present study was to measure the cranial base width, including the width of the maxilla, and to measure the bilateral angulation of the petrous portion of the temporal bone and the sphenoid bone in 3-month-old children with complete clefts and in 3-month-old children with an incomplete cleft of the lip, and to compare the two groups. Fifty-two children with complete clefts (CLP) without associated malformations comprised the test group. Forty-eight children with a minor, incomplete cleft lip (CL) constituted the control group. The results of the comparison showed marked differences between the CLP and CL groups. In the CLP children, the cranial base width and the bilateral angulation of the sphenoid bone increased. An increased angulation was also seen between left and right sides of the pars petrosa. Furthermore, increased maxillary width was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Cartilage↗
PubMed1995

Human prenatal craniofacial development related to brain development under normal and pathologic conditions.

A survey is given of current knowledge of the interrelationship between facial, cranial and brain development in humans. First, normal facial, cranial (mandible, maxilla, palatine bone, cranial base, theca cranii, dentition), and brain development are described separately. Then, developmental interrelationships are illustrated under normal and pathologic conditions (cleft lip and palate, holoprosencephaly, anencephaly, amniotic band sequence). New observations are described in detail, and references are given to previously published articles. A close interconnection exists between the development of the face, the craniofacial skeleton, and the brain. This is illustrated by new observations in cleft palate fetuses and new theories about the etiology of holoprosencephaly and tooth agenesis. The survey focuses, moreover, on the importance of the face and the cranial base in endocrine development. Borderlines between face regions and cranial regions with different developmental origin are set up for future elucidation of the etiology behind syndromes involving the craniofacial regions.

Amniotic Band Syndrome↗
PubMed1994

[Morphometric studies on the fetal development of the human mandible].

Serial sections of eleven human mandibles of embryos and fetuses ranging in size from 18 mm CRL to 66 mm CRL were computer-graphically reconstructed. The extension of the Meckel cartilage and the mandibular bony structures were morphometrically studied. In emphasis the study encompassed measurements portraying length, width, dorsal opening angle, and the position of the mental foramen. In addition five mandibles of human embryos and fetuses with a size range between 30 and 50 mm CRL were radiographically examined. Results showed that in the younger specimens between 21 and 29 CRL size development of the structures of the mandible and the development of overall fetal body size take place independently from each other. During further development a change in the form of the mandible from a wide V over an acute V to a more rounded U form was observed.

Cartilage↗
PubMed1994

Craniofacial morphology in patients with multiple congenitally missing permanent teeth.

The purpose of this study was to examine the association between the number of congenitally missing permanent teeth, excluding third molars, and the craniofacial morphology. The sample comprised 118 children with five or more congenitally missing teeth. Twenty-seven reference points were digitized from lateral cephalometric radiographs and 13 angular measurements of craniofacial morphology were calculated. After an initial analysis, the sample was divided into two subsamples, one with 5-12 missing teeth and the other with 13-21 missing teeth. Within each subsample there was no significant association between number of missing teeth and the angular variables, but a comparison between the two subsamples showed significantly smaller mandibular plane inclination (NSL/ML, NL/ML) and gonial angle (RL/ML), and a more prognathic mandible (s-n-pg) in the subsample with more than 12 teeth missing. It is suggested that the difference in morphology could be due to a reduced vertical development of the lower face, caused by a reduced occlusal support in the subsample with more than 12 congenitally missing teeth.

Adolescent↗
PubMed1994

Aetiological aspects of mandibular tooth agenesis--focusing on the role of nerve, oral mucosa, and supporting tissues.

The purpose of the present investigation was to consider possible aetiological aspects of mandibular tooth agenesis by comparing the pattern of mandibular molar and premolar agenesis with radiological evidence of the mandibular canal. Orthopantomograms from 33 children affected by agenesis of at least four premolar and/or molar teeth in the mandible were investigated. Three children were affected by ectodermal dysplasia. Two anthropological mandibles with absence of mandibular canals were included in the study for comparison. According to the investigation, agenesis should be divided into three groups, based on an analysis of agenesis location, the presence of nerve canals in the jaws, and finally, data on possible bone, skin and oral mucosa abnormalities. The three aetiological groups suggested are: agenesis related to nerve tissue, agenesis related to the oral epithelium, and agenesis related to the supporting tissue.

Adolescent↗
PubMed1994

Elevated vibration perception threshold in young patients with type 1 diabetes in comparison to non-diabetic children and adolescents.

The vibration perception threshold (VPT) was investigated by biothesiometry in 61 children (28 boys) with Type 1 diabetes, mean age 15.5 (range 10-21) years, duration of diabetes 6.9 (range 1-19) years, and in 76 healthy children (39 males), mean age 13.8 (range 10-19) years. The measurements were performed in triplicate on the right second finger and on the right first toe. The vibration perception threshold was significantly increased (p < 0.0001) in the young diabetic patients (mean +/- SD, finger 4.1 +/- 1.1 V, toe: 5.7 +/- 1.3 V) compared to healthy children (finger 3.4 +/- 0.9 V, toe: 3.6 +/- 1.3 V). Twenty percent of adolescents with Type 1 diabetes had a VPT above the 95th percentiles (finger: 5 V, toe 6.5 V) for normal control children. In healthy controls a significant correlation (r = 0.27, p < 0.01) was found for VPT in finger versus toe. This relationship was not significant in the diabetic group and may be due to reduced sensitivity of the fingertips caused by frequent blood glucose testing. Age, Tanner stage and height were significantly correlated to VPT (toe) in both diabetic and normal boys, while duration of diabetes, HbA1c, arterial blood-pressure and body mass index were not significantly associated with VPT in any of the groups. The results indicate that changes in VPT appears early in childhood and emphasize a need for further studies of subclinical neuropathy in young patients with Type 1 diabetes.

Adolescent↗
PubMed1994

Diagnostic distinction between anencephaly and amnion rupture sequence based on skeletal analysis.

The axial skeletal development of eight second trimester aborted fetuses, clinically diagnosed as amnion rupture sequence with cranial involvement, was examined radiographically and histologically. Three of the eight fetuses showed axial skeletal malformation in the spine and the craniofacial skeleton corresponding to the malformations seen in anencephaly. These are vertebral body malformations, consisting of double corpora and of osseous malformations in the components of the cranial base, the corpus of the occipital bone, and the postsphenoid bone. These types of malformation, which have previously been described, are located along the original course of the notochord. The findings show that it is possible by means of radiography of the axial skeleton to distinguish between anencephalic fetuses which become secondarily involved in amnion rupture and fetuses which were initially normally developed. The method supplements detailed fetal examination and provides important information for genetic counselling.

Amniotic Band Syndrome↗
PubMed1994

Midline maxillofacial skeleton in human anencephalic fetuses.

The purpose of this study was to describe the midline maxillofacial skeleton (the axial skeleton anterior to the sella turcica) in 15 human anencephalic fetuses (14-19 weeks of gestation) by radiography and histology, and to relate the findings to skeletal patterns in the remaining part of the axial skeleton. Four patterns in the maxillofacial skeleton were recognized: normal structures, slightly deformed (6 cases); cleft palate (3 cases); incomplete nasal septum (3 cases); multilocular ethmoid cartilage (3 cases). No association was found between skeletal patterns in the different parts of the axial skeleton. The study demonstrates the existence of a developmental borderline in the anencephalic axial skeleton in the region of the sella turcica. It is presumed that this borderline indicates the boundary between skeletal tissue developed around the notochord (posterior axial skeleton) and the anterior skeletal components derived from neural crest cells.

Anencephaly↗
PubMed1993

Immunocytochemical demonstration of nerve growth factor receptor (NGF-R) in developing human fetal teeth.

Evidence is accumulating that nerve growth factor receptor (NGF-R or p75NGFR) can mediate cell growth and differentiation of non-neuronal cells. NGF-R expression was studied in developing teeth of human embryos and fetuses between the 6th and 18th weeks of gestation, using a monoclonal mouse-anti-human NGF-R antibody. In contrast to earlier findings in rodents, the NGF-R expression of the human dental papilla was found to be transient. NGF-R was present in the condensing ecto-mesenchymal cells of the dental papilla in the early cap stage tooth germ. In later developmental stages, a shift of the NGF-R expression from the papilla to the cytoplasmic membrane of the inner enamel epithelium (IEE) was demonstrated. As in rodent odontogenesis, the NGF-R immunoreactivity of the IEE remained until the odontoblasts started secretion of predentinal matrix in the late bell state. The mitotic activity in the IEE was detected by an antibody against proliferating cell nuclear antigen (PCNA) and showed that the NGF-R expression of the IEE decreased as the cell proliferation ceased. We propose that NGF-R may, be involved in differential and/or proliferative events of human odontogenesis.

Embryo, Mammalian↗