PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “AMELOGENESIS IMPERFECTA”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed2002

Autosomal-dominant hypoplastic form of amelogenesis imperfecta caused by an enamelin gene mutation at the exon-intron boundary.

Amelogenesis imperfecta (AI) is currently classified into 14 distinct subtypes based on various phenotypic criteria; however, the gene responsible for each phenotype has not been defined. We performed molecular genetic studies on a Japanese family with a possible autosomal-dominant form of AI. Previous studies have mapped an autosomal-dominant human AI locus to chromosome 4q11-q21, where two candidate genes, ameloblastin and enamelin, are located. We studied AI patients in this family, focusing on these genes, and found a mutation in the enamelin gene. The mutation detected was a heterozygous, single-G deletion within a series of 7 G residues at the exon 9-intron 9 boundary of the enamelin gene. The mutation was detected only in AI patients in the family and was not detected in other unaffected family members or control individuals. The male proband and his brother showed hypoplastic enamel in both their deciduous and permanent teeth, and their father showed local hypoplastic defects in the enamel of his permanent teeth. The clinical phenotype of these patients is similar to that of the first report of AI caused by an enamelin gene mutation. Thus, heterogeneous mutations in the enamelin gene are responsible for an autosomal-dominant hypoplastic form of AI.

Amelogenesis Imperfecta↗
PubMedDate not supplied

The effects of acid-etching on enamel from different clinical variants of amelogenesis imperfecta: an SEM study.

PURPOSE: Successful bonding of resins to teeth affected by amelogenesis imperfecta (AI) may be highly dependent on how the enamel responds to acid etching. The aim of this study was to determine, using scanning electron microscopy (SEM), the types of etching pattern achieved with 37% phosphoric acid on dental enamel of 5 clinical variants of AI, namely, pitted hypoplastic, smooth hypoplastic, X-linked (male), X-linked (female), and hypomineralized. METHODS: A normal premolar and primary molar from two healthy patients were used as controls. The enamel was scanned before and after acid etching for 1 min. In the normal, control teeth, the three classical etching patterns were produced: type 1, in which the prism cores are preferentially removed; type 2, in which the prism peripheries are removed, and type 3 in which the removal of enamel does not relate to prism structure. RESULTS: In the normal primary molar, patterns of types 2 and 3 were generally produced. In the AI teeth, the effects of acid etching reflected the clinical variant of AI. All three etch patterns were observed in the enamel surrounding the pits in the pitted type of AI and in the bands of normal enamel in the female with X-linked AI, as well as in the hypomineralized variant. In contrast, no typical etch patterns could be detected in the enamel from the male patient with X-linked variant, as well as from the enamel affected by the smooth hypoplastic variant. CONCLUSIONS: The lack of typical etching patterns in these variants may be the result of abnormal prism structure, or the standard etching time and/or acid concentration may be inappropriate for the abnormal enamel. The results of this study may have useful applications in the restoration of teeth affected by AI.

Acid Etching, Dental↗
PubMed1986

Hereditary amelogenesis imperfecta. An epidemiological, genetic and clinical study in a Swedish child population.

Hereditary Amelogenesis Imperfecta (HAI) is a hereditary dental enamel disorder showing a varying clinical picture. Reviewing the literature, there seems to be a need for a better knowledge in many aspects concerning this disorder, not least to enhance the therapeutical approach for individuals suffering from HAI. The aims of this thesis, were to identify and to classify hereditary enamel defects and to estimate their prevalence in a Swedish child population. The oral health of individuals diagnosed as having HAI was also analysed and evaluated. 425 000 children, from the western part of Sweden, aged 3-19 years, were screened in order to identify individuals showing enamel defects of hereditary linkage. In this way, 105 children were identified. They were clinically classified into 12 different subgroups. Genetic analyses were also made. In 99 children, the oral health status was analysed and evaluated. In another patient material, 26 individuals aged 8-20 years and with HAI, the anterior open bite malocclusion was studied. The prevalence of HAI was estimated to be 1 case in 4000. In analyses of genetic data, eight different subgroups of HAI were identified based on the two major types, the hypoplastic and the hypomineralized. The hypoplastic, rough-pitted type with autosomal dominance, represented the most common HAI disorder. A low caries susceptibility was found in children with severely hypoplastic and hypomineralized enamel. Bacteriological and salivary data in the children could not fully support the findings regarding the low caries susceptibility. A high number of restorations were recorded predominantly in severe cases of the hypomineralized type, in which group gingival inflammation, plaque and dental calculus also were frequently found. The open bite occlusion could be associated both with the hypoplastic and the hypomineralized types of HAI. This malocclusion was considered to be of skeletal origin. The prevalence found shows that HAI is a fairly common enamel disorder with a varying clinical expressivity. The oral health findings in individuals suffering from the disorder indicate a need for early treatment planning.

Adolescent↗
PubMed2003

Enamelin and autosomal-dominant amelogenesis imperfecta.

Dental enamel forms as a progressively thickening extracellular layer by the action of proteins secreted by ameloblasts. The most abundant enamel protein is amelogenin, which is expressed primarily from a gene on the X-chromosome (AMELX). The two most abundant non-amelogenin enamel proteins are ameloblastin and enamelin, which are expressed from the AMBN and ENAM genes, respectively. The human AMBN and ENAM genes are located on chromosome 4q13.2. The major secretory products of the human AMELX, AMBN, and ENAM genes have 175, 421, and 1103 amino acids, respectively, and are all post-translationally modified, secreted, and processed by proteases. Mutations in AMELX have been shown to cause X-linked amelogenesis imperfecta (AI), which accounts for 5% of AI cases. Mutations in ENAM cause a severe form of autosomal-dominant smooth hypoplastic AI that represents 1.5%, and a mild form of autosomal-dominant local hypoplastic AI that accounts for 27% of AI cases in Sweden. The discovery of mutations in the ENAM gene in AI kindreds proved that enamelin is critical for proper dental enamel formation and that it plays a role in human disease. Here we review how enamelin was discovered, what is known about enamelin protein structure, post-translational modifications, processing by proteases, and its potentially important functional properties such as its affinity for hydroxyapatite and influence on crystal growth in vitro. The primary structures of human, porcine, mouse, and rat enamelin are compared, and the human enamelin gene, its structure, chromosomal localization, temporal and spatial patterns of expression, and its role in the etiology of amelogenesis imperfecta are discussed.

Amelogenesis↗
PubMed1989

Microradiographic study of amelogenesis imperfecta.

A material of 22 primary and 4 permanent teeth from 22 children with amelogenesis imperfecta (AI) were examined by microradiographic techniques. The children were part of a patient material earlier examined in genetical and clinical studies. The results were compared with corresponding data two non-affected control groups and correlated with the available clinical and genetical data. Teeth were examined from seven of the eight different variants of AI seen in the clinical study. In most cases both hypoplasias and areas of hypomineralization were observed in the same tooth, indicating that both the secretory and the maturation phases of the amelogenesis are affected in AI. In teeth from children with the same clinical variant but different inheritance patterns, no specific finding could be related to a specific inheritance pattern. The findings in the one boy with AI as an X-linked trait were unique in this material. In all control teeth except one, no hypoplasisas or areas of hypomineralization were found in the enamel. In conclusion, the subclassification of AI into different forms can be questioned. Variations in clinical and histologic characteristics connected with the same inheritance pattern suggest that the genetic defect, in conjuction with a large biological variation, could explain the multiplicity in clinical expressivity that characterizes AI.

Amelogenesis Imperfecta↗
PubMed1995

Amelogenesis imperfecta--towards a new classification.

This editorial reviews the history of the classification of amelogenesis imperfecta (AI). The limitations of the existing classification systems are discussed. An alternative classification is proposed based upon the molecular defect, biochemical result, mode of inheritance and phenotype in the family involved. While not all of the criteria for the proposed classification can yet be addressed, this scheme is proposed for future classification of AI cases and families.

Amelogenesis Imperfecta↗
PubMedDate not supplied

Dental development in amelogenesis imperfecta: a controlled study.

The present investigation studied dental development in 23 subjects with amelogenesis imperfecta (AI), aged 4.2 to 15.6 years, compared with 46 race-, age-, and sex-matched, healthy, normal controls. The dental ages of the children were assessed from panoramic radiographs using previously established methods. Their chronologic ages at the time of radiographic examination were compared with their dental ages. The results showed that all subjects with AI showed a significant acceleration of dental age of approximately 1.13 +/- 0.78 years compared with control children (P < 0.001). All children were consistently affected regardless of the AI variant. Furthermore, the study found a six-fold increase (26.1 vs. 4.3%) in tendency of AI patients to show impaction of the permanent teeth and associated anomalies such as follicular cysts. These results may be important in planning orthodontic treatment in AI patients, and indicate that they should have early screening to detect these abnormalities.

Adolescent↗
PubMed2002

Identification of a locus on chromosome 2q11 at which recessive amelogenesis imperfecta and cone-rod dystrophy cosegregate.

A consanguineous Arab pedigree in which recessive amelogenesis imperfecta (AI) and cone-rod dystrophy cosegregate, was screened for linkage to known retinal dystrophy and tooth abnormality loci by genotyping neighbouring microsatellite markers. This analysis resulted in linkage with a maximum lod score of 7.03 to the marker D2S2187 at the achromatopsia locus on chromosome 2q11, and haplotype analysis placed the gene(s) involved in a 2 cM/5 Mb interval between markers D2S2209 and D2S373. The CNGA3 gene, known to be involved in achromatopsia, lies in this interval but thorough analysis of its coding sequence revealed no mutation. Furthermore, affected individuals in four consanguineous recessive pedigrees with AI but without CRD were heterozygous at this locus, excluding it as a common cause of non-syndromic recessive AI. It remains to be established whether this pedigree is segregating two closely linked mutations causing disparate phenotypes or whether a single defect is causing pathology in both teeth and eyes.

Amelogenesis Imperfecta↗
PubMed1997

DNA diagnosis of X-linked amelogenesis imperfecta (AIH1).

Mutations in the amelogenin gene, AMGX, are known to cause X-linked amelogenesis imperfecta (AIH1). We have used DNA single-strand conformational polymorphism analysis and DNA sequencing to diagnose this disorder unequivocally in two related boys aged 3 and 7 years, respectively, from a family in which an existing mutation in the amelogenin gene is segregating.

Alleles↗
PubMedDate not supplied

Enamel pretreatment with sodium hypochlorite to enhance bonding in hypocalcified amelogenesis imperfecta: case report and SEM analysis.

Bonding composite resin to enamel of teeth affected by amelogenesis imperfecta (AI) is often problematic, especially in cases with poorly mineralized, friable enamel. Difficulty in bonding hypomineralized enamel can significantly limit the restorative and orthodontic treatment options for AI patients. In this report, we document a novel approach to bonding AI enamel by pretreating the tooth surface with 5% sodium hypochlorite (NaOCl), resulting in improved bonding of an orthodontic bracket to a previously impacted maxillary canine.

Acid Etching, Dental↗