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PubMed1997

[Amelogenesis imperfecta in young patients].

Amelogenesis imperfecta is a genetic disturbance in the formation of enamel. The condition can be classified as a hypoplastic type and a hypomineralized type. Both types are normally very inconvenient for the patient and treatment should be started as soon as possible. Dental treatment should aim at maintaining the height of the bite and improvement of occlusal function and esthetics. In a few case presentations the possibilities and limitations of adhesive composite restorations in young patients with amelogenesis imperfecta are discussed.

Amelogenesis Imperfecta↗
PubMed1997

Scanning electron microscopic study of hypoplastic type amelogenesis imperfecta in primary teeth.

Amelogenesis imperfecta (AI) comprises a diverse group of hereditary enamel disorders that are characterized by hypoplastic and in some cases hypomineralized defects. Purpose of this investigation was to characterize the ultrastructure of autosomal recessive smooth hypoplastic amelogenesis imperfecta enamel. The primary teeth that exfoliated physiologically were studied by scanning electron microscopy. By using scanning electron microscope, multiple shallow depressions and deep tubular voids were observed. Irregular enamel, irregularities in enamel crystallites, hypoplastic areas on the enamel surface were seen.

Amelogenesis Imperfecta↗
PubMed1982

An investigation of the association between anterior open-bite and amelogenesis imperfecta.

Fifty subjects with amelogenesis imperfecta were investigated clinically and with cephalometric radiography in order to determine the prevalence and nature of the anterior open-bite, which has been reported in association with these enamel defects. Anterior open-bite occurred in 24 percent of the subjects and was always associated with a severe discrepancy in the vertical relationship of the jaws. This vertical dysgnathia also occurred in a further 20 percent who did not have anterior open-bite. It is suggested that the frequent association of anterior open-bite and amelogenesis imperfecta is caused by a genetically determined anomaly of craniofacial development, rather than by local factors influencing alveolar growth.

Adolescent↗
PubMed2003

Relationship of phenotype and genotype in X-linked amelogenesis imperfecta.

X-linked amelogenesis imperfectas (AI) resulting from mutations in the amelogenin gene (AMELX) are phenotypically and genetically diverse. Amelogenin is the predominant matrix protein in developing enamel and is essential for normal enamel formation. To date, 12 allelic AMELX mutations have been described that purportedly result in markedly different expressed amelogenin protein products. We hypothesize that these AMELX gene mutations result in unique and functionally altered amelogenin proteins that are associated with distinct amelogenesis imperfecta phenotypes. The AMELX mutations and associated phenotypes fall generally into three categories. (1) Mutations (e.g., signal peptide mutations) causing a total of loss of amelogenin protein are associated with a primarily hypoplastic phenotype (though mineralization defects also can occur). (2) Missense mutations affecting the N-terminal region, especially those causing changes in the putative lectin-binding domain and TRAP (tyrosine rich amelogenin protein) region of the amelogenin molecule, result in a predominantly hypomineralization/hypomaturation AI phenotype with enamel that is discolored and has retained amelogenin. (3) Mutations causing loss of the amelogenin C terminus result in a phenotype characterized by hypoplasia. The consistent association of similar hypoplastic or hypomineralization/hypomaturation AI phenotypes with specific AMELX mutations may help identify distinct functional domains of the amelogenin molecule. The phenotype-genotype correlations in this study suggest there are important functional domains of the amelogenin molecule that are critical for the development of normal enamel structure, composition, and thickness.

Amelogenesis Imperfecta↗
PubMed2002

Amelogenesis imperfecta: a scanning electron microscopic and histopathologic study.

Amelogenesis imperfecta (AI) is a hereditary defect in enamel formation affecting both primary and permanent dentition. Scanning electron microscopic investigation is one of the most effective methods in diagnosing and identifying the type of amelogenesis imperfecta. The aim of this study was to investigate the ultrastructure of different types of amelogenesis imperfecta enamel. The primary teeth of three children with AI aged 4, 10 and 11-years-old were studied by scanning electron microscopy and irregular enamel, irregularities in enamel crystallites, hypoplastic areas on the enamel surface were seen. Histopathological evaluation revealed predentin areas with irregular canaliculi between normal dentin and internal resorption areas in the pulp tissue. Conclusively, in amelogenesis imperfecta, enamel tissue is mostly affected besides minor defects in dentinal and pulpal tissue.

Amelogenesis Imperfecta↗
PubMed2002

Restoring function and esthetics in a patient with amelogenesis imperfecta: a case report.

Amelogenesis imperfecta is a hereditary disorder that affects enamel on primary and permanent teeth. It is a rare dental disease but represents a major restorative challenge for the dentist. A 14-year-old boy presented with sensitive, discolored, and mutilated teeth and a decreased vertical dimension of occlusion. The aim of treatment was to reduce dental sensitivity, to restore esthetics, and to correct the vertical dimension of occlusion. To modify the occlusion, and to protect the dentin from chemical and thermal attacks, nickel-chrome onlays were placed on the molars. To improve the esthetics of the incisors and premolars, resin composite restorations were applied. The patient was regularly recalled during the postoperative period. Radiographic and clinical examinations 10 months posttreatment revealed no evidence of disorders associated with the restored teeth or their supporting structures.

Adolescent↗
PubMed1990

Current treatment modalities in the conservative restoration of amelogenesis imperfecta: a case report.

Amelogenesis imperfecta is an inherited disorder involving enamel formation that affects the appearance of the teeth to various degrees. Cosmetic rehabilitation of these patients has been open to a variety of treatment options. Complete-coverage restorations are often recommended. Patients are occasionally averse to this because of the extensive preparation of tooth structure or lack of financial means. In the past, conservative measures were inadequate because the lack of enamel bonding did not allow a durable restoration. Presently, with the use of glass-ionomer cements and dentinal adhesives, dentin-resin bond strengths are approaching those of etched enamel. This article discusses the use of glass-ionomer cement, dentinal priming agents, and etched enamel to create a strong bond between restorative material and tooth structure that provides not only satisfactory esthetics, but also a durable restoration.

Adult↗
PubMed1997

Ameloblastin gene (AMBN) maps within the critical region for autosomal dominant amelogenesis imperfecta at chromosome 4q21.

Amelogenesis imperfecta (AI) is a broad group of hereditary enamel defects that is characterized by a high degree of clinical diversity. Recently, the local hypoplastic form of autosomal dominant AI (AIH2) has been mapped to human chromosome 4q in a 17.6-cM region. This locus has been further refined to a 4-Mb interval between D4S2421 and Albumin. Recently, a cDNA clone for an enamel matrix protein, ameloblastin (AMBN), has been isolated. In this report, we have isolated a PAC human genomic clone containing the human AMBN gene. The AMBN was mapped by two color fluorescence in situ hybridization using two P1 genomic clones for sequence tagged site (STS) markers, D4S400 and D4S409, which flank the critical AIH2 region. Our results place AMBN at 4q21 between D4S409 (4q13) and D4S400 (4q21). Furthermore, the AMBN PAC genomic clone was shown to contain three STS markers, D4S2604, D4S2670, and D4S2609, which are contained within the critical region defined by six Swedish families with AIH2. AMBN is therefore a strong candidate gene for AIH2.

Amelogenesis Imperfecta↗
PubMed2006

A new locus for autosomal dominant amelogenesis imperfecta on chromosome 8q24.3.

Amelogenesis imperfecta (AI) is a collective term used to describe phenotypically diverse forms of defective tooth enamel development. AI has been reported to exhibit a variety of inheritance patterns, and several loci have been identified that are associated with AI. We have performed a genome-wide scan in a large Brazilian family segregating an autosomal dominant form of AI and mapped a novel locus to 8q24.3. A maximum multipoint LOD score of 7.5 was obtained at marker D8S2334 (146,101,309 bp). The disease locus lies in a 1.9 cM (2.1 Mb) region according to the Rutgers Combined Linkage-Physical map, between a VNTR marker (at 143,988,705 bp) and the telomere (146,274,826 bp). Ten candidate genes were identified based on gene ontology and microarray-facilitated gene selection using the expression of murine orthologues in dental tissue, and examined for the presence of a mutation. However, no causative mutation was identified.

Amelogenesis Imperfecta↗
PubMed1977

Ultrastructural study of amelogenesis imperfecta.

An ultrastructural study of teeth with amelogenesis imperfecta revealed various aspects of microcavities in the enamel surface, which ranged from isolated imprints of ameloblasts corresponding to the mildest lesions at the end of amelogenesis, to pits caused by the death of 20 to 30 ameloblasts at the beginning of amelogenesis. Abnormalities in the shape of the prisms can be observed. Further, crystals are distributed randomly within a prism or at the junction of 2 contiguous prisms while intercrystalline spaces are widened, indicating in various places the lack of a preferred orientation of the crystals. In amelogenesis imperfecta, two different crystalline periods are found: 1 of about 250 A, the other of about 500 A and over. The fact that amorphous areas are found among the crystals of enamel may be related to different stages of crystallization. However, it was not possible to find any lattice defect.

Ameloblasts↗
PubMed2004

Amelogenesis imperfecta: the multidisciplinary approach. A case report.

Amelogenesis imperfecta is a hereditary developmental disorder of the dental enamel, in both primary and permanent dentition. The main clinical characteristics are extensive loss of tooth tissue, poor esthetics, and tooth sensitivity. Transmission of the gene takes place by either autosomal, dominant X-linked, or recessive modes. This clinical report describes a treatment sequence based on a multidisciplinary approach. A 21-year-old girl with hypoplastic amelogenesis imperfecta was referred to the Ege University School of Dentistry clinic. She was concerned about the poor appearance and sensitivity of her teeth. The patient presented with an anterior open bite, although orthodontic treatment had been completed previously. Periodontal gingivectomy of her posterior teeth followed by endodontic treatment where indicated was proposed. The prosthodontic treatment consisted of metal ceramic fixed partial dentures of precious alloy. At the end of treatment, function and esthetics were improved to a level acceptable to both the patient and the dental team.

Adult↗
PubMed1994

Localization of a gene for autosomal dominant amelogenesis imperfecta (ADAI) to chromosome 4q.

Amelogenesis imperfecta (AI), is an inherited odontological disease which affects the formation of enamel. We report a linkage analysis study performed on three Swedish families, where the affected members had an autosomal dominant variant of AI (ADAI) clinically characterized as local hypoplastic. Significant linkage to microsatellite markers on chromosome 4q were obtained. Recombinations localized the ADAI locus to a chromosome region which contains both a locus for the dental disorder dentinogenesis imperfecta and the albumin gene. Serum albumin has been suggested to play a role in enamel formation, and the albumin gene is therefore a candidate gene for this genetic disease.

Amelogenesis Imperfecta↗
PubMedDate not supplied

A spontaneous mutation: amelogenesis imperfecta with cysts in rats.

Amelogenesis imperfecta (AI) is an inherited dental disease of enamel formation in humans, and there are various phenotypes due to the combination of enamel quality and quantity. We encountered four female IGS rats with spontaneous AI including odontogenic cysts in the incisor teeth. Histopathologically, in the incisors of the rats, the enamel organ was disorganized with the remaining enamel matrix residing within the enamel space. The expanding cysts derived from the enamel organ were formed in the periosteal connective tissue on the labial side. At the bottom of the tooth germs, the precursor cells of the epithelial root sheath were arranged regularly and the enamel organs were preserved to the same degree as those of normal rats. In the molar teeth of the affected rats an enamel matrix remained on the neck and crown of the erupted teeth; however, no abnormality was observed at the tooth root. Although an animal model of AI has been developed from mutants of the SHR-SP rat strain, the present cases represent another potential model of the disease because of the differences in the way the enamel matured and the odontogenic cyst formation in the incisors.

Amelogenesis Imperfecta↗
PubMed2000

Mutational analysis of X-linked amelogenesis imperfecta in multiple families.

Seven mutations in the amelogenin gene are associated with X-linked amelogenesis imperfecta. These mutations can produce reductions in the amount of enamel and the degree of mineralization. Two families have been identified from western North Carolina exhibiting features of amelogenesis imperfecta, characterized by brown enamel in affected males and interposed vertical bands of normal appearing and brown enamel in presumably heterozygous females. Mutational analysis reveals a C-A mutation in exon 6 at codon 41 of the X-chromosomal amelogenin gene, resulting in a pro-thr change in all individuals having the amelogenesis imperfecta phenotype. This mutation was previously reported in a family with X-linked hypomaturation amelogenesis imperfecta. There is no known relationship between any of the three families but the presence of similar phenotypes and common mutations suggests they may be distantly related. For individuals from all three families, the haplotype for six highly polymorphic loci flanking the amelogenin gene was determined. A common haplotype was demonstrated among two of the three families, suggesting that the mutation may have been inherited from a common ancestor. The finding that the third family had a distinct haplotype may indicate that the C-A mutation at codon 41 represents a mutational hotspot that occurs with greater frequency than other known amelogenin gene mutations. The phenotype resulting from this mutation was highly consistent in affected male members of the same family and between families.

Amelogenesis Imperfecta↗
PubMed2005

Functional and esthetic rehabilitation in amelogenesis imperfecta with all-ceramic restorations: a case report.

Amelogenesis imperfecta is a hereditary condition resulting in poor tooth development, severe anomalies, or complete absence of enamel. Enamel lesions may be the only characteristic of this condition or may be part of a generalized syndrome. Amelogenesis imperfecta can be characterized by enamel hypoplasia and/or hypomaturation or hypocalcification of the existing teeth. Restoration for patients with this condition should be oriented toward the functional and esthetic rehabilitation and the protection of the existing teeth. This paper presents a description of a patient's oral rehabilitation with all-ceramic veneers and crowns after extensive crown lengthening. The diagnostic procedure is also reported in detail. A microscopic examination was also performed on an extracted third molar under polarized light.

Adult↗
PubMed1989

[Amelogenesis imperfecta and hypothalamo-hypophyseal insufficiency].

Eleven patients with hypopituitarism, medio-facial hypoplasia and amelogenesis imperfecta were examined. The hypothalamo-pituitary dysfunction affected somatotrophic, gonadotrophic, corticotrophic and thyrotrophic function. The facial anomalies included medio-facial hypoplasia with hypertelorism and amelogenesis imperfecta. The latter--hypoplastic in nature--was noted in all anterior teeth and affected both dentitions. The enamel defect was confirmed on microscopic examination of an impacted tooth. The spectrum of malformation may also present as amelogenesis imperfecta in association with somatotropin deficiency. A genetic mechanism may possibly account for the clinical elements.

Amelogenesis Imperfecta↗