Structural and compositional alteration of tooth enamel in hereditary epidermolysis bullosa

Case Report: Crown Resorption in a Patient With Junctional Epidermolysis Bullosa and Amelogenesis Imperfecta With LAMB3 Gene Mutations

Background: Epidermolysis bullosa (EB) corresponds to a series of conditions characterized by extreme fragility of the skin and/or mucous membranes. Of the four main types of EB, junctional EB (JEB) is the most associated with alterations in the teeth. The purposes of this study were to determine the clinical, histopathological, and ultrastructural characteristics of teeth with amelogenesis imperfecta (AI) in a patient with JEB, and compare them with control teeth, and correlate the findings with the mutations present in the patient.

Case Report: The study was conducted on a 10-year-old patient with JEB carrier of two recessive mutations in the LAMB3 gene and absence of the laminin-332 protein (LM-332), determined by immunofluorescence on a skin biopsy. The patient presents hypoplastic AI with very thin and yellow-brown colored enamel. Extraction of two permanent molars was performed due to pain and soft tissue covering the crown, resembling pulp polyp or hyperplastic gingiva. Light and scanning electron microscopy (SEM) revealed very thin enamel varying from complete absence to 60 μm, absence of normal prismatic structure, and presence of a cross-banding with a laminated appearance. The histopathological study revealed granulation tissue causing external crown resorption.

Conclusion: Although coronary resorption has been reported in patients with syndromic and non-syndromic AI, this is the first clinicopathological report of coronary resorption in partially erupted teeth in patients with JEB with mutations in the LAMB3 gene and hypoplastic AI. In patients with this condition, the presence of partially erupted teeth with soft tissue covering part of the crown, without a periodontal pocket, and with a radiographic image of partial coronal radiolucency should lead to suspicion of external coronary resorption.

Clinical practice guidelines: Oral health care for children and adults living with epidermolysis bullosa

BACKGROUND

Inherited epidermolysis bullosa (EB) is a genetic disorder characterized by skin fragility and unique oral features.

AIMS

To provide (a) a complete review of the oral manifestations in those living with each type of inherited EB, (b) the current best practices for managing oral health care of people living with EB, (c) the current best practices on dental implant-based oral rehabilitation for patients with recessive dystrophic EB (RDEB), and (d) the current best practice for managing local anesthesia, principles of sedation, and general anesthesia for children and adults with EB undergoing dental treatment.

METHODS

Systematic literature search, panel discussion including clinical experts and patient representatives from different centers around the world, external review, and guideline piloting.

RESULTS

This article has been divided into five chapters: (i) general information on EB for the oral health care professional, (ii) systematic literature review on the oral manifestations of EB, (iii) oral health care and dental treatment for children and adults living with EB-clinical practice guidelines, (iv) dental implants in patients with RDEB-clinical practice guidelines, and (v) sedation and anesthesia for adults and children with EB undergoing dental treatment-clinical practice guidelines. Each chapter provides recommendations on the management of the different clinical procedures within dental practice, highlighting the importance of patient-clinician partnership, impact on quality of life, and the importance of follow-up appointments. Guidance on the use on nonadhesive wound care products and emollients to reduce friction during patient care is provided.

CONCLUSIONS

Oral soft and hard tissue manifestations of inherited EB have unique patterns of involvement associated with each subtype of the condition. Understanding each subtype individually will help the professionals plan long-term treatment approaches.

DENTAL ENAMEL FORMATION AND IMPLICATIONS FOR ORAL HEALTH AND DISEASE

Dental enamel is the hardest and most mineralized tissue in extinct and extant vertebrate species and provides maximum durability that allows teeth to function as weapons and/or tools as well as for food processing. Enamel development and mineralization is an intricate process tightly regulated by cells of the enamel organ called ameloblasts. These heavily polarized cells form a monolayer around the developing enamel tissue and move as a single forming front in specified directions as they lay down a proteinaceous matrix that serves as a template for crystal growth. Ameloblasts maintain intercellular connections creating a semi-permeable barrier that at one end (basal/proximal) receives nutrients and ions from blood vessels, and at the opposite end (secretory/apical/distal) forms extracellular crystals within specified pH conditions. In this unique environment, ameloblasts orchestrate crystal growth via multiple cellular activities including modulating the transport of minerals and ions, pH regulation, proteolysis, and endocytosis. In many vertebrates, the bulk of the enamel tissue volume is first formed and subsequently mineralized by these same cells as they retransform their morphology and function. Cell death by apoptosis and regression are the fates of many ameloblasts following enamel maturation, and what cells remain of the enamel organ are shed during tooth eruption, or are incorporated into the tooth's epithelial attachment to the oral gingiva. In this review, we examine key aspects of dental enamel formation, from its developmental genesis to the ever-increasing wealth of data on the mechanisms mediating ionic transport, as well as the clinical outcomes resulting from abnormal ameloblast function.

Biomineralization of a self-assembled-, soft-matrix precursor: Enamel

Enamel is the bioceramic covering of teeth, a composite tissue composed of hierarchical organized hydroxyapatite crystallites fabricated by cells under physiologic pH and temperature. Enamel material properties resist wear and fracture to serve a lifetime of chewing. Understanding the cellular and molecular mechanisms for enamel formation may allow a biology-inspired approach to material fabrication based on self-assembling proteins that control form and function. Genetic understanding of human diseases expose insight from Nature's errors by exposing critical fabrication events that can be validated experimentally and duplicated in mice using genetic engineering to phenocopy the human disease so that it can be explored in detail. This approach led to assessment of amelogenin protein self-assembly which, when altered, disrupts fabrication of the soft enamel protein matrix. A misassembled protein matrix precursor results in loss of cell to matrix contacts essential to fabrication and mineralization.

Evaluation of internal consistency of the epidermolysis bullosa oropharyngeal severity score (EBOS)

OBJECTIVE

To evaluate the internal consistency of the epidermolysis bullosa oropharyngeal severity score (EBOS).

MATERIALS AND METHODS

Data from 92 patients of varying EB types/sub-types already described in a previous multi-center study were re-analyzed via the coefficient Cronbach's α (CR-α). Additionally, the corrected item total correlation between each item and the items' overall score with Pearson's product-moment correlation (ρ) was calculated.

RESULTS

The alpha coefficient for the mean total score of 17 items is 0.941. The inter-observer reliability for disease severity score was excellent for oral medicine specialist (α = 0.924) and dermatologist (α = 0.916) and the intra-observer reliability was good at Time 1 (α = 0.895) and Time 2 (α = 0.897). The analysis of CR-α per single item revealed that alpha was greater than 0.904 for disease activity and 0.743 for structural damage, after the elimination of four items for oral medicine specialist and greater than 0.898 for disease activity and 0.769 for structural damage after the elimination of five items for dermatologist. Similarly the analysis of the corrected items-EBOS correlation showed that the same items do not correlate very well (ρ < 0.4) with the overall EBOS.

CONCLUSIONS

The EBOS turned out to have a strong and reliable internal consistency, as the majority of the EBOS' items were consistent with each other.

Oral health care for patients with epidermolysis bullosa--best clinical practice guidelines

OBJECTIVE

  To provide the users with information on the current best practices for managing the oral health care of people living with EB.

METHODS

  A systematic literature search, in which the main topic is dental care in patients with Epidermolysis Bullosa, was performed. Consulted sources, ranging from 1970 to 2010, included MEDLINE, EMBASE, CINAHL, The Cochrane Library, DARE, and the Cochrane controlled trials register (CENTRAL). In order to formulate the recommendations of the selected studies the SIGN system was used. The first draft was analysed and discussed by clinical experts, methodologists and patients representatives on a two days consensus meeting. The resulting document went through an external review process by a panel of experts, other health care professionals, patient representatives and lay reviewers. The final document was piloted in three different centres in United Kingdom, Czech Republic and Argentina.

RESULTS

  The guideline is composed of 93 recommendations divided into 3 main areas: 1) Oral Care--access issues, early referral, preventative strategies, management of microstomia, prescriptions and review appointments 2) Dental treatment: general treatment modifications, radiographs, restorations, endodontics, oral rehabilitation, periodontal treatment, oral surgery and orthodontics, and 3) Anaesthetic management of dental treatment.

CONCLUSIONS

  A preventive protocol is today's dental management approach of choice.

Biological synthesis of tooth enamel instructed by an artificial matrix

The regenerative capability of enamel, the hardest tissue in the vertebrate body, is fundamentally limited due to cell apoptosis following maturation of the tissue. Synthetic strategies to promote enamel formation have the potential to repair damage, increase the longevity of teeth and improve the understanding of the events leading to tissue formation. Using a self-assembling bioactive matrix, we demonstrate the ability to induce ectopic formation of enamel at chosen sites adjacent to a mouse incisor cultured in vivo under the kidney capsule. The resulting material reveals the highly organized, hierarchical structure of hydroxyapatite crystallites similar to native enamel. This artificially triggered formation of organized mineral demonstrates a pathway for developing cell fabricated materials for treatment of dental caries, the most ubiquitous disease in man. Additionally, the artificial matrix provides a unique tool to probe cellular mechanisms involved in tissue formation further enabling the development of tooth organ replacements.

A mouse model of generalized non-Herlitz junctional epidermolysis bullosa

Epidermolysis bullosa (EB) is a class of intractable, rare, genetic disorders characterized by fragile skin and blister formation as a result of dermal-epidermal mechanical instability. EB presents with considerable clinical and molecular heterogeneity. Viable animal models of junctional EB (JEB), that both mimic the human disease and survive beyond the neonatal period, are needed. We identified a spontaneous, autosomal recessive mutation (Lamc2(jeb)) due to a murine leukemia virus long terminal repeat insertion in Lamc2 (laminin gamma2 gene) that results in a hypomorphic allele with reduced levels of LAMC2 protein. These mutant mice develop a progressive blistering disease validated at the gross and microscopic levels to closely resemble generalized non-Herlitz JEB. The Lamc2(jeb) mice display additional extracutaneous features such as loss of bone mineralization and abnormal teeth, as well as a respiratory phenotype that is recognized but not as well characterized in humans. This model faithfully recapitulates human JEB and provides an important preclinical tool to test therapeutic approaches.

Systemic disorders and their influence on the development of dental hard tissues: a literature review

OBJECTIVES

This report highlights the influence of a number of disorders with systemic physiological effects that impact on the development of dental hard tissues. It focuses in particular, on the pathological effects of systemic conditions with less well recognised, but no less important, impacts on dental development. Such conditions, include cystic fibrosis, HIV/AIDS, leukaemia, Alstrom syndrome, hypophosphatasia, Prader-Willi syndrome, Tricho-dento-osseous syndrome, tuberous sclerosis, familial steroid dehydrogenase deficiency and epidermolysis bullosa. These, along with developmental and environmental causes of enamel and dentine defects, are discussed and the possible aetiology of such effects are proposed. Furthermore, the dental management and long-term dental care of these patients is outlined.

SOURCES

MEDLINE/PubMed.

CONCLUSIONS

Enamel and dentine defects can present with a wide spectrum of clinical features and may be caused by a variety of factors occurring throughout tooth development from before birth to adulthood. These may include host traits, genetic factors, immunological responses to cariogenic bacteria, saliva composition, environmental and behavioural factors and systemic diseases. These diseases and their spectrum of clinical manifestations on the organs affected (including the dentition) require an increased knowledge by dental practitioners of the disease processes, aetiology, relevant treatment strategies and prognosis, and must encompass more than simply the management of the dental requirements of the patient. It is important that the impact of the disease and its treatment, particularly in respect of immunosuppression where dental interventions may become life-threatening, is also taken into consideration.

Extracutaneous manifestations and complications of inherited epidermolysis bullosa: part II. Other organs

It is well known, primarily via case reports and limited case series, that nonepithelial tissues may become injured in patients with epidermolysis bullosa. Only recently, however, have there been data generated from large, well characterized cohorts. Our objective is to provide dermatologists with a comprehensive review of each of these major extracutaneous complications, with a summary of the pertinent literature and evidence-based recommendations for surveillance, evaluation, and management. Some epidermolysis bullosa subtypes are at risk for severe injury of the bone marrow, musculoskeletal system, heart, kidney, and teeth, and for the development of squamous cell carcinoma, basal cell carcinoma, or malignant melanoma. If untreated, significant morbidity or mortality may result.

Dystrophic epidermolysis bullosa: Oral findings and problems

Dystrophic epidermolysis bullosa (DEB) is one of the three major types of epidermolysis bullosa (EB), an inherited cutaneous disease with blister formation following minor trauma. A subtype of DEB is recessive dystrophic epidermolysis bullosa, Hallopeau-Siemens type (RDEB-HS), where marked scarring leads to deformities of extremities. In RDEB-HS the mucous membranes may also be involved and form adhesions with ankyloglossia and microstomia. Oral hygiene is difficult. A 7-year-old boy with RDEB-HS was brought to the Johannes Gutenberg University dental clinic with dental pain. He had multiple carious lesions, poor oral hygiene and gingivitis. Because he was noncompliant and had microstomia, he required dental therapy under general anesthesia. The recall visits over the past two years had demonstrated that the dental health of this patient with RDEB-HS could be maintained by means of improved oral home care, using antibacterial agents.

Epidermolysis bullosa and dental developmental age

OBJECTIVES

The dental development of permanent mandibular teeth in a small group of children with dystrophic epidermolysis bullosa (DEB) was assessed from radiographs and compared to a healthy, age-and-sex-matched control group.

METHODS

This was a retrospective radiographic cross-sectional study. The sample consisted of a group of 44 children aged between 4 and 15 years with DEB and healthy, age-and-sex-matched controls. Two quantitative methods of assessing tooth formation were used: (1) a combination of information about tooth length and apex width; and (2) the use of tooth length to predict age. Panoramic radiographs were digitized in order to determine tooth length and apex width. Dental age was calculated, and the difference with real age was tested with Student's t-test.

RESULTS

The dentition of both the DEB and control groups was slightly delayed. Using the first method, the delay was 0.34 +/- 0.87 years for the DEB group and 0.29 +/- 0.97 years for the control group. Using the second method, the delay was 0.49 +/- 1.18 years for the DEB group and 0.23 +/- 0.62 years for the control group. This delay was not statistically significant for either method.

CONCLUSIONS

The dental formation of permanent mandibular teeth in the group of children with DEB was not significantly different to that found in the control group.

Review: extracellular matrix regulates tooth morphogenesis

Mineralized tissues are unique in that they use proteins to attract and organize calcium and phosphate ions into a structured mineral phase, thus precise knowledge of the expression and extracellular distribution of matrix proteins is very important to understand their function. Tooth development is regulated by sequential and reciprocal interactions between neural crest-derived mesenchymal cells and the oral environment. However, the precise molecular mechanisms that mediate interactions between epithelium and mesenchymal cells are not clear, although basement membrane (BM) components have been shown to play important roles in these regulatory events. In addition, the extracellular matrix layer, whose main components are laminin, collagen IV, nidogen, and sulfated proteoglycan, and the BM layer are both considered to be involved with cell proliferation and differentiation. During tooth morphogenesis, extracellular matrices are dramatically changed. Further, the BM components, laminin and collagen IV support dental epithelium; however, in the late stage, they begin the processes of enamel matrix secretion and calcification, after which the BM structure between the dental epithelium and mesenchyme disappears. In addition, tooth abnormalities associated with several kinds of human diseases that cause mutations in the extracellular matrix, as well as the molecular mechanisms of the basement membrane and enamel matrix during tooth morphogenesis, are not clearly understood. In our review, we discuss the role of the extracellular matrix, with focus on the BM and enamel matrix during tooth morphogenesis.

Normal formation and development defects of the human dentition

Oral health and systemic health are intimately related, and a thorough evaluation of the oral health of children is critical in providing appropriate health care. By understanding the normal sequence and patterns of tooth development, clinicians can readily identify children who deviate from normal dental development and provide appropriate interventions or make appropriate referrals. Developmental defects of the human dentition are not uncommon and can severely adversely affect the physical and psychological health of children. Despite the severity of some developmental defects of the dentition, the ability to diagnose and manage these conditions, in most cases, allows children the benefit of optimal oral health.