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.

Exclusion of known gene for enamel development in two Brazilian families with amelogenesis imperfecta

Amelogenesis imperfecta (AI) is a genetically heterogeneous group of diseases that result in defective development of tooth enamel. Mutations in several enamel proteins and proteinases have been associated with AI. The object of this study was to evaluate evidence of etiology for the six major candidate gene loci in two Brazilian families with AI. Genomic DMA was obtained from family members and all exons and exon-intron boundaries of the ENAM, AMBN, AMELX, MMP20, KLK4 and Amelotin gene were amplified and sequenced. Each family was also evaluated for linkage to chromosome regions known to contain genes important in enamel development. The present study indicates that the AI in these two families is not caused by any of the known loci for AI or any of the major candidate genes proposed in the literature. These findings indicate extensive genetic heterogeneity for non-syndromic AI.

Overdenture as a restorative option for hypocalcified-hypoplastic amelogenesis imperfecta: a case report.

AIM: The aim of this report is to describe the restorative treatment of an 18-year-old patient diagnosed with autosomal recessive hypocalcified-hypoplastic amelogenesis imperfecta (AI). BACKGROUND: Esthetic and functional rehabilitations in AI cases are challenging and should consider individual aspects, such as age, socioeconomic status, AI type, and intraoral condition. REPORT: AI was diagnosed in an 18-year-old patient. SUMMARY: Considering the short length of crowns and roots, patient life expectancy, minimal invasiveness, amount of treatment time required, and lower costs, oral rehabilitation with overdentures provided an adequate functional and esthetic rehabilitation of the patient. CLINICAL SIGNIFICANCE: This report demonstrated overdentures to be a viable, relatively inexpensive, and non-invasive treatment choice of a patient with AI with concerns about treatment longevity, invasiveness, cost, esthetics, and long-term maintenance.

Assessment of restorative treatment of patients with amelogenesis imperfecta

Purpose: The purpose of this study was to assess restorative treatment outcomes in the mixed dentition of amelogenesis imperfecta (AI) patients and determine the postrehabilitation oral health status and satisfaction of the patients. Methods: Clinical and radiographic examinations were performed on eight AI patients, who had 74 restorations placed in permanent incisors and molars, to allow evaluation of the integrity of the restorations and periodontal status post-treatment. Subjects completed a survey regarding esthetics, function, and sensitivity. Results: Among the 74 restorations evaluated, seven were lost; of the remaining restorations, 31 were posterior, and 36 were anterior. Ten were rated clinically unacceptable. Teeth with stainless steel crowns had a moderate gingival index (mean=2.3) and plaque index (mean=2.0) scores. Widening of the periodontal ligament and pulp canal obliteration were common radiographic findings. Subject's recall of satisfaction regarding esthetics (P=.002) and sensitivity (brushing-P=.03; eating-P=.01) showed a statically significant difference before and after treatment. Conclusions: During mixed dentition, teeth with amelogenesis imperfecta may be restored with conventional treatment modalities. Direct restorations should be considered interim with multiple repairs anticipated. Post-treatment, gingival inflammation and plaque accumulation were observed. Subjects were satisfied with their appearance and reported a decrease of hypersensitivity. © 2013 Publishing Technology.

Conservative treatment for amelogenesis imperfecta: a case report

Amelogenesis imperfecta is a hereditary condition that can alter the thickness, color, and shape of tooth enamel. Recent adhesive materials and techniques have provided less invasive treatment options. This case report presents the treatment of a patient whose anterior teeth had color alterations, white spots, pits, and shape defects. Using a more conservative technique, the mandibular and maxillary anterior teeth were restored using veneer direct composite restorations. After 6 years, the restorations demonstrated no deterioration, and no pathology was seen in association with the rehabilitation.

Noninvasive and multidisciplinary approach to the functional and esthetic rehabilitation of amelogenesis imperfecta: a pediatric case report

Case Report. An 8-year-old girl with amelogenesis imperfecta (AI) reported unsatisfactory aesthetics, difficulty in mastication, and dental hypersensitivity. The intraoral examination observed mixed dentition, malocclusion in anteroposterior relationships, anterior open bite, and dental asymmetry. A hypoplastic form of AI was diagnosed in the permanent dentition. A multidisciplinary planning was performed and divided into preventive, orthopedic, and rehabilitation stages. Initially, preventive treatment was implemented, with fluoride varnish applications, in order to protect the fragile enamel and reduce the dental sensitivity. In the second stage, the patient received an interceptive orthopedic treatment to improve cross-relationship of the arches during six months. Finally, the rehabilitation treatment was executed to establish the vertical dimension. In the posterior teeth, indirect composite resin crowns were performed with minimally invasive dental preparation. Direct composite resin restorations were used to improve the appearance of anterior teeth. Follow-Up. The follow-up was carried out after 3, 6, 12, and 18 months. After 18 months of follow-up, The restoration of integrity, oral hygiene, and patient satisfaction were observed . Conclusion. Successful reduction of the dental hypersensitivity and improvement of the aesthetic and functional aspects as well as quality of life were observed.

A multidisciplinary approach to the functional and esthetic rehabilitation of amelogenesis imperfecta and open bite deformity: a case report

The treatment of amelogenesis imperfecta (AI) with an anterior open bite (AOB) is a challenge for the clinician and often requires a multidisciplinary team of specialists. Most often, patients suffering from these conditions are young and a good functional and esthetic long-term result must be aspired. This clinical report illustrates the orthodontic, maxillofacial, restorative, and prosthodontic rehabilitation of a 20-year-old woman with a hypoplastic form of AI and an AOB malocclusion, having received treatment for the last 6 years. It included adhesive resin composite restorations, orthodontical and maxillofacial surgery with a one-piece Le Fort I osteotomy, and a genioplasty. Subsequent prosthodontic therapy consisted of 28 all-ceramic crowns whereby a solid interdigitation, a canine guidance, and consistent and regular contacts between tooth crowns could be achieved to assure a good functional and esthetic oral situation. The tooth preparation techniques guaranteed minimally invasive treatment. The patient was affected very positively. CLINICAL SIGNIFICANCE: This article describes an interdisciplinary approach to the successful treatment of a patient with a hypoplastic form of amelogenesis imperfecta over a period of 6 years. It starts with a discussion of the conservative steps taken during adolescence and concludes with the final prosthetic rehabilitation with all-ceramic crowns after reaching adulthood.

Enamel microabrasion: an overview of clinical and scientific considerations

Superficial stains and irregularities of the enamel are generally what prompt patients to seek dental intervention to improve their smile. These stains or defects may be due to hypoplasia, amelogenesis imperfecta, mineralized white spots, or fluorosis, for which enamel microabrasion is primarily indicated. Enamel microabrasion involves the use of acidic and abrasive agents, such as with 37% phosphoric acid and pumice or 6% hydrochloric acid and silica, applied to the altered enamel surface with mechanical pressure from a rubber cup coupled to a rotatory mandrel of a low-rotation micromotor. If necessary, this treatment can be safely combined with bleaching for better esthetic results. Recent studies show that microabrasion is a conservative treatment when the enamel wear is minimal and clinically imperceptible. The most important factor contributing to the success of enamel microabrasion is the depth of the defect, as deeper, opaque stains, such as those resulting from hypoplasia, cannot be resolved with microabrasion, and require a restorative approach. Surface enamel alterations that result from microabrasion, such as roughness and microhardness, are easily restored by saliva. Clinical studies support the efficacy and longevity of this safe and minimally invasive treatment. The present article presents the clinical and scientific aspects concerning the microabrasion technique, and discusses the indications for and effects of the treatment, including recent works describing microscopic and clinical evaluations.

Reabilitação estética com facetas em pacientes com amelogénese imperfeita

A Amelogénese Imperfeita é uma anomalia hereditária que interfere no desenvolvimento do esmalte, pode variar em seu grau de intensidade, podendo afetar o esmalte tanto na sua qualidade, quanto na sua quantidade e em ambas as dentições. Existem pelo menos catorze subtipos diferentes de amelogénese imperfeita, sendo as do tipo hipoplásico, hipomaturado, hipocalcificado e hipoplásico ou hipomaturado com taurodontia segundo o seu fenótipo e quinze subtipos, segundo o seu modo de transmissão. Segundo a literatura, os pacientes com amelogénese imperfeita, independentemente do subtipo presente, apresentam complicações orais semelhantes: estética dentária comprometida, sensibilidade dentária e diminuição da dimensão vertical de oclusão. O tratamento destes pacientes assume um papel relevante, na medida em que requer cuidados especiais, já que esta doença acarreta, por norma, problemas psicológicos e interfere com o autoestima do individuo. É notória, atualmente, uma oferta variada de opções reabilitadoras ao dispor do Médico Dentista, que ajudarão o mesmo a restabelecer a estética e função. Os tratamentos são variados e por vezes complexos, podem ser desenvolvidos de forma conservadora ou invasiva. Contudo, a escolha do melhor tratamento será consequência da gravidade da patologia e de fatores inerentes ao próprio paciente. Neste estudo, abordamos as facetas, como uma alternativa reabilitadora, que com o avanço e melhorias na área da Dentisteria Estética, nomeadamente no que diz respeito à adesão à dentina, parecem ser uma opção credível. Assim, o objetivo desta dissertação é demonstrar e elucidar a reabilitação dos defeitos associados a esta doença com a utilização de facetas diretas e indiretas. Foram efetuadas pesquisas e consulta de livros, monografias, dissertações, artigos em base de dados como o Pubmed/Medline, para que conseguíssemos realizar uma discussão sobre o mesmo tema e desta forma encontrar uma adequada resposta a todas as nossas inquietações sobre esta questão.

Defeitos de desenvolvimento do esmalte e respetivo tratamento

As estruturas dentárias são revestidas pelo esmalte dentário. O esmalte é um tecido de alta dureza, avascular e predominantemente branco. No entanto, distingue-se dos outros tecidos mineralizados do corpo pela sua incapacidade de remodelação. Devido a esse facto qualquer alteração que ocorra, quer ao longo da vida, quer no seu desenvolvimento fica, permanentemente, registada (Seow, 1997). Procurou-se nesta monografia aprofundar os conhecimentos sobre os mais comuns defeitos de desenvolvimento do esmalte existentes, assim como o respetivo tratamento. Para a realização desta monografia foram utilizados os seguintes motores de busca B-on, PubMed, Science Direct e Sci-elo, para a realização da pesquisa de informação, aplicando-se um critério de seleção temporal dos últimos 10 anos. As palavras-chaves e combinações de palavras utilizadas nos motores de busca referidos para a realização da pesquisa foram “Enamel”, “Enamel Development”, “Enamel Defects”, “Amelogenisis Imperfecta”, “Hypoplasia”. Dos 300 artigos encontrados nesta pesquisa, foram selecionados 68. O desenvolvimento dos tecidos dentários é um processo complexo conhecido por odontogénese, podendo ser simplisticamente dividido em três fases Fase de Botão, Fase de Capuz e por último a Fase de Campânula (Thesleff et al.,2009) Existem inúmeros defeitos de desenvolvimento do esmalte registados na literatura, não sendo mesmo possível em muitos casos enquadrar indubitavelmente o referido defeito numa categoria, ou até atribuir-lhe uma designação (Seow, 1997). Optou-se pela sua relevância e epidemiologia abordar nesta monografia os seguintes defeitos: Defeitos de desenvolvimento do esmalte; Opacidades; Opacidade difusa; Hipoplasia; Amelogenese imperfeita e todas as suas categorias; Fluorose e manchas por tetraciclinas assim como os seus respectivos tratamentos. Os defeitos de desenvolvimento de esmalte apresentam diversas características próprias e outras semelhantes entre si, verificando-se assim diversas possibilidades de tratamentos a realizar, uns mais invasivos e outros menos, que vão desde microabrasões na superfície do esmalte, à colocação de cerâmicas, dependendo sempre da preferência do paciente e do seu poder socioeconómico (Azevedo DT et al., 2011). Conclui-se que apesar de todos os problemas que acarretam quer a nível estético quer a nível funcional para os indivíduos nos quais não existe uma grande gravidade das lesões esses casos podem ser resolvidos por um Médico Dentista generalista desde que este tenha o conhecimento adequado dos protocolos de atuação.

Increased intra-cortical porosity reduces bone stiffness and strength in pediatric patients with osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a heritable disease occurring in one out of every 20,000 births. Although it is known that Type I collagen mutation in OI leads to increased bone fragility, the mechanism of this increased susceptibility to fracture is not clear. The aim of this study was to assess the microstructure of cortical bone fragments from patients with osteogenesis imperfecta (OI) using polarized light microscopy, and to correlate microstructural observations with the results of previously performed mechanical compression tests on bone from the same source. Specimens of cortical bone were harvested from the lower limbs of three (3) OI patients at the time of surgery, and were divided into two groups. Group 1 had been subjected to previous micro-mechanical compression testing, while Group 2 had not been subjected to any prior testing. Polarized light microscopy revealed disorganized bone collagen architecture as has been previously observed, as well as a large increase in the areal porosity of the bone compared to typical values for healthy cortical bone, with large (several hundred micron sized), asymmetrical pores. Importantly, the areal porosity of the OI bone samples in Group 1 appears to correlate strongly with their previously measured apparent Young's modulus and compressive strength. Taken together with prior nanoindentation studies on OI bone tissue, the results of this study suggest that increased intra-cortical porosity is responsible for the reduction in macroscopic mechanical properties of OI cortical bone, and therefore that in vivo imaging modalities with resolutions of ~ 100 μm or less could potentially be used to non-invasively assess bone strength in OI patients. Although the number of subjects in this study is small, these results highlight the importance of further studies in OI bone by groups with access to human OI tissue in order to clarify the relationship between increased porosity and reduced macroscopic mechanical integrity.

The IFITM5 mutation c.-14C > T results in an elongated transcript expressed in human bone; And causes varying phenotypic severity of osteogenesis imperfecta type V

Background The genetic mutation resulting in osteogenesis imperfecta (OI) type V was recently characterised as a single point mutation (c.-14C > T) in the 5' untranslated region (UTR) of IFITM5, a gene encoding a transmembrane protein with expression restricted to skeletal tissue. This mutation creates an alternative start codon and has been shown in a eukaryotic cell line to result in a longer variant of IFITM5, but its expression has not previously been demonstrated in bone from a patient with OI type V. Methods Sanger sequencing of the IFITM5 5' UTR was performed in our cohort of subjects with a clinical diagnosis of OI type V. Clinical data was collated from referring clinicians. RNA was extracted from a bone sample from one patient and Sanger sequenced to determine expression of wild-type and mutant IFITM5. Results: All nine subjects with OI type V were heterozygous for the c.-14C > T IFITM5 mutation. Clinically, there was heterogeneity in phenotype, particularly in the manifestation of bone fragility amongst subjects. Both wild-type and mutant IFITM5 mRNA transcripts were present in bone. Conclusions The c.-14C > T IFITM5 mutation does not result in an RNA-null allele but is expressed in bone. Individuals with identical mutations in IFITM5 have highly variable phenotypic expression, even within the same family.