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PubMed1988

Taurodontism in 47,XXY males: an effect of the extra X chromosome on root development.

Effects of an extra X chromosome on root development were studied in males with a 47,XXY chromosome constitution. Occurrence of taurodontism in the permanent molars of the lower jaw was noted from orthopantomograms of 30 Finnish 47,XXY males, 16 of their first-degree relatives, and a sample of 157 normal males and females. Nine, or 30%, or the 47,XXY males had at least one mandibular molar which was classified as taurodont. Only hypotaurodont teeth were found, and the teeth affected were all either second or third molars. None of the control relatives showed taurodontism. In the population sample, four individuals, or 2.5%, had taurodont teeth. A change in the mitotic activity of the cells of the developing teeth is one possible factor that can affect root formation leading to the development of taurodontism.

Adolescent↗
PubMed1996

The chemical composition of tooth enamel in recessive dystrophic epidermolysis bullosa: significance with respect to dental caries.

Previous reports have linked the prevalence of tooth abnormalities with high caries experience in the different types of epidermolysis bullosa (EB). However, it is not known to what extent the apparent susceptibility to enamel caries is due to disease-related altered enamel chemistry in these cases. The aim of this study was to characterize the enamel of teeth from patients suffering from recessive epidermolysis bullosa dystrophica (rEBD) in terms of its mineral content, carbonate content, protein content, and amino acid composition. The results showed that dental enamel from these patients was essentially normal in terms of its chemistry. It is therefore concluded that the high caries experience in recessive dystrophic epidermolysis bullosa patients is probably related to other factors, such as compromised oral hygiene and prolonged oral clearance due to extensive oral soft tissue damage and a cariogenic diet.

Amino Acids↗
PubMed1989

Review of terminology, classifications, and indices of developmental defects of enamel.

A wide variety of terms and definitions are used to describe various developmental defects of enamel. Some are simple descriptive clinical terms, and others are linked with the causative agent or the histopathology of the defect. Some confusion exists as to the most appropriate type of index to use to measure defects of enamel due to fluoride ingestion (dental fluorosis). This is primarily due to difficulties some researchers have in distinguishing between defects of fluoride and non-fluoride origin. This problem has resulted in the development of specific fluorosis indices and purely descriptive indices. The main fluorosis indices are those of Dean, Thylstrup and Fejerskov, and the TSIF Index. Dean's Index does not provide adequate information on the distribution of fluorosis within the dentition and is not sensitive at high fluorosis levels. The Thylstrup and Fejerskov Index is related to the histology of florosis; however, the initial minute changes observed on dry enamel surfaces are of little esthetic importance. The TSIF Index does overcome some of the limitations of Dean's Index. The DDE Index has replaced the Al-Alousi Index as the main descriptive index. The DDE Index is time-consuming, and the analyses of data are complicated. Modifications have now been proposed to make it simpler to use and the data more meaningful. Further research needs to be carried out into both the validity of the fluorosis indices and making the DDE Index more universally acceptable.

Dental Enamel↗
PubMed1989

Hypocalcification and hypoplasia in primary teeth of pre-school children from different ethnic groups in South Africa.

A study was completed in 1985/86 which examined the dental health of pre-school children from different ethnic groups and communities in South Africa: rural black, urban black, urban colored, urban Indian, and urban white. Enamel defects were recorded in primary teeth by use of the HHI, an index developed to measure hypocalcification and hypoplasia of enamel. The findings showed that colored children had the greatest number of enamel defects. The teeth most commonly affected were the maxillary anterior teeth and mandibular molar teeth. It is suggested that further epidemiological studies utilizing the HHI should be undertaken in pre-school children, especially from developing countries, to gain more information on the causes of enamel defects in the primary dentition and the possible use of such findings to predict nutritional health of individuals.

Child, Preschool↗
PubMed1989

Prevalence of developmental defects of tooth enamel (DDE) in a pediatric hospital department of dentistry population (1).

This paper reports the first part of a three-part study of developmental defects of tooth enamel in a pediatric hospital population. The dental records of 8411 children who were discharged from the Department of Dentistry at the Royal Children's Hospital, Melbourne, Australia, between 1960 and 1987 were divided into an experimental group of 7518 patients comprising 25 groups of medical conditions, and a control group of 893 children who had dental disorders only. The aim of the study was to investigate the prevalence of hypoplastic and severe-opacity developmental defects of tooth enamel (DDE), in children and adolescents with major medical disorders, and to compare the prevalence with that in the control group of normal children. The prevalence figures obtained for the different medical conditions in this study agreed generally with those of other recent investigators. The high prevalence of defects found in Rubella Embryopathy children (81.8%) and in children with Prematurity alone (56.5%) is surprising, whereas the prevalence of 27.9% defects in Clefts of Lip and Palate and 26.4% defects in Clefts of Lip and Alveolus are probably well below the true prevalence. The control group prevalence was 9.3%, which is higher than in some other studies of 'normal' children. A pediatric hospital is a most useful source of fully documented medical and dental histories for the investigation of possible relationships between medical disorders and developmental defects of tooth enamel. The control group prevalence was 9.3%, which is higher than in some other studies of normal children. A pediatric hospital is a most useful source of fully documented medical and dental histories for the investigation of possible relationships between medical disorders and developmental defects of tooth enamel.

Adolescent↗
PubMed1989

Hypocalcification and hypoplasia in permanent teeth of children from different ethnic groups in South Africa assessed with a new index.

A new descriptive index, the HHI (hypocalcification-hypoplasia index), is described for comparing enamel defects in groups of people. The index was used in a study completed in 1986, in which 1251 11-year-old children from different ethnic groups resident in South Africa were examined: 210 rural black, 203 urban black, 206 urban colored, 426 urban Indian, and 206 urban white. The index can be used as a screening examination, and the results from these different ethnic groups are presented.

Child↗
PubMed2004

Amelogenesis imperfecta in a new animal model--a mutation in chromosome 5 (human 4q21).

Candidate genes for amelogenesis imperfecta (AI) and dentinogenesis imperfecta (DI) are located on 4q21 in humans. We tested our hypothesis that mutations in the portion of mouse chromosome 5 corresponding to human chromosome 4q21 would cause enamel and dentin abnormalities. Male C3H mice were injected with ethylnitrosourea (ENU). Within a dominant ENU mutagenesis screen, a mouse mutant was isolated with an abnormal tooth enamel (ATE) phenotype. The structure and ultrastructure of teeth were studied. The mutation was located on mouse chromosome 5 in an interval of 9 cM between markers D5Mit18 and D5Mit10. Homozygotic mutants showed total enamel aplasia with exposed dentinal tubules, while heterozygotic mutants showed a significant reduction in enamel width. Dentin of mutant mice showed a reduced content of mature collagen cross-links. We were able to demonstrate that a mutation on chromosome 5 corresponding to human chromosome 4q21 can cause amelogenesis imperfecta and changes in dentin composition.

Amelogenesis Imperfecta↗
PubMed2005

Three-dimensional cone beam computerized tomography in orthodontics.

There has been an escalating interest in three-dimensional imaging devices over the last decade. Orthodontists are beginning to appreciate the advantages that the third dimension gives to clinical diagnosis, treatment planning and patient education. This article focuses on the cutting edge technology of cone beam CT, which utilizes conventional X-ray technology and computerized volumetric reconstruction to reproduce a three-dimensional image. A variety of applications and range of issues associated with this technology will be discussed.

Alveolar Process↗
PubMed1988

The diagnostic value of panoramic radiographs in children aged nine to ten years.

The increased awareness of the possible harmful effects of ionizing radiation has resulted in concern at the number of panoramic radiographs taken in General Dental Practice. A study has been carried out to examine the diagnostic value obtained from panoramic radiographs taken at 9-10 years of age. Nine-hundred-and-eighty-two radiographs were examined and 261 (26.5 per cent) showed findings which would be of significance in orthodontic diagnosis and treatment planning.

Child↗
PubMed1989

An inverted upper lateral incisor.

A case is presented of an inverted upper lateral incisor in an 11-year-old patient. It is believed that involvement of this tooth is previously unreported.

Child↗
PubMed2001

Preclinical evaluation of the cardiotoxicity of PK2: a novel HPMA copolymer-doxorubicin-galactosamine conjugate antitumour agent.

PK2 is a polymeric anticancer conjugate composed of an N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer backbone and pendant doxorubicin (DOX) linked via a Gly-Phe-Leu-Gly peptide spacer. Additionally galactose residues are present to facilitate liver targeting. To justify clinical evaluation of PK2 it was necessary to determine its late cardiotoxicity compared to that of free DOX. A well standardised Sprague-Dawley rat model was used with either intravenous (i.v.) administration (4, 8 and 12 mg/kg DOX equivalent) or intraperitoneal (i.p.) administration (12, 18, 24 and 36 mg/kg DOX equivalent) of PK2. This variation in the route was due to the limited solubility of PK2 at higher doses. PK2 showed two to three times less acute toxicity (assessed by the maximum reduction in body weight in the first 2 weeks) than free DOX, and both compounds were less toxic when given i.p.. No animals given PK2 i.v. showed clinical signs of cardiotoxicity, the only toxicity seen was abnormal tooth growth (approximately 50% of the animals receiving 12 mg/kg, DOX equivalent). In contrast, several animals receiving free DOX (1-4 mg/kg) i.v. died due to cardiotoxicity in an approximately dose-related manner. All animals receiving free DOX (4 mg/kg) died by 12 weeks. Following i.p. administration of PKZ there were only two late deaths related to cardiotoxicity and these were in the 24 mg/kg DOX equivalent group. All animals receiving PK2 at the highest dose (36 mg/kg DOX equivalent) died within 4 weeks, cardiotoxicity was not the main contributing factor. In this study, PK2 displayed a approximately 5-fold reduction in cardiotoxicity relative to free DOX and this supported the progression of PK2 into early clinical investigation.

Animals↗
PubMed1989

Premaxillary hyperdontia in medieval Norwegians: a radiographic study.

An excavation of a part of the graveyard of St Olav's church, Trondheim, Norway, uncovered 389 tombs from the medieval period (1100-1600). Radiographic examination of 140 skulls with an intact premaxilla revealed hyperdontia in the form of a mesiodens in two (1.4%) cases. This is within the same range as similar medieval and present Nordic populations. Change in functional pattern does not seem to influence the prevalence.

Adolescent↗