Pathohistology of undecalcified primary teeth in vitamin D-resistant rickets: review and report of two cases

Oral health and oral-health-related quality of life in people with X-linked hypophosphatemia

BACKGROUND

X-linked hypophosphatemia (XLH) is a type of vitamin D-resistant rickets. It is the most common form of it and is related with oral health problems. This study aimed to analyze the OHRQoL of people suffering from XLH and measure physical oral health to confirm or refute evidence of reduced oral health.

METHODS

The German version of the Oral Health Impact Profile (OHIP-14G), was used to measure OHRQoL. All study participants underwent clinical examination, and oral health was scored using the Physical Oral Health Index (PhOX).

RESULTS

A total of 26 people participated in the study, of whom five were male and 21 were female. The average participant age was 40.9 ± 12.8 years. The OHIP-14G score was 14.3 (± 12.1; 95% CI: 9.37. 19.16) points (range 0-44 points). The PhOX score was 77.1 (± 9.9; 95% CI: 73.10-81.13) points (range 61-95 points).

CONCLUSIONS

The results of this study confirm that oral health and OHRQoL are both reduced in the studied cohort of people affected by XLH. Particular attention should be paid to perfect oral hygiene in people with XLH, as the impaired enamel mineralisation increases the risk of caries and thus also the occurrence of apical infections.

Dental manifestations and treatment of hypophosphatemic rickets: A case report and review of literature

BACKGROUND

The treatment and management of patients suffering from hypophosphatemic rickets (HR) remain a major challenge for dental practitioners and affected patients.

OBJECTIVES

To report a case of HR presenting with specific dental findings and to review the dental manifestations and treatment of HR patients.

METHODS

Case: A 32-year-old male presented with multiple dental abscesses and short stature. A thorough history was taken followed by clinical oral examination, and relevant radiological investigation was done. Literature research: In 2020, electronic literature searches were carried out in PubMed and complemented by a careful assessment of the reference lists of the identified relevant papers. Articles and reports fulfilled the inclusion criteria: indexed reviews, case series and case reports in English and restricted to human studies were considered.

RESULTS

The intraoral examination revealed multiple dental abscesses and general periodontal disease; the radiographic examination showed poorly defined lamina dura, large pulp chambers and periapical lesions. Based on the contents of the 43 articles identified in the search, the current knowledge of dental manifestations, treatment and management of HR was summarized.

CONCLUSIONS

As HR is a multisystem disease, multidisciplinary care is needed. By summarizing current evidences, we proposed an evidence-based dental management and provided recommendations on diagnosis and treatment of the disease. It is of profound clinical significance to acquire knowledge of the dental manifestations and provide optimal treatment options for patients.

Presentation and non-surgical endodontic treatment of two patients with X-linked hypophosphatemia: a case report

AIM

To describe two patients with X-linked hypophosphatemia presenting with spontaneous signs of pulpal necrosis in multiple intact teeth. The presentation and management are discussed, along with the diagnostic and endodontic treatment challenges.

SUMMARY

Two young male patients with X-linked hypophosphatemia were referred to the Department of Restorative Dentistry at the Edinburgh Dental Institute, UK for management of dental infection. Both patients were referred due to their unusual clinical presentation and abnormal root canal morphology. They subsequently presented on multiple occasions with pain or sinus tracts over a 3- and 5-year period whilst under care. Clinical examination revealed intact teeth with buccal swellings, draining buccal sinuses and negative responses to pulp sensibility testing. Radiographic examination, generally consisting of periapical radiographs, revealed intact teeth with a range of unusual morphological features including large pulp chambers, wide canals, short roots and open apices, all with associated periapical radiolucencies. Due to the unusual morphology, some teeth required apexification with a mineral trioxide aggregate plug. Patient 1 underwent root canal treatment on teeth 21 and 43 over a 3-year period. Patient 2 underwent root canal treatment on 10 permanent teeth over a 5-year period. At follow-up, both patients were asymptomatic and clinically the teeth had no signs of infection or periapical inflammation. Radiographic examination confirmed complete resolution of the apical radiolucencies on 11 out of 12 teeth. Favourable outcomes have been demonstrated up to a follow-up of 4.5 years.

KEY LEARNING POINTS

Patients with X-linked hypophosphatemia may present with 'spontaneous' signs of pulp necrosis in multiple teeth in the absence of caries and trauma posing a diagnostic challenge. Abnormal morphological features, including wide canals and open apices, may present challenges during root canal treatment. Outcomes demonstrate that an appropriate root canal treatment protocol, including the application of apexification procedures, may be implemented to successfully manage such cases.

Selected Nanomaterials' Application Enhanced with the Use of Stem Cells in Acceleration of Alveolar Bone Regeneration during Augmentation Process

Regenerative properties are different in every human tissue. Nowadays, with the increasing popularity of dental implants, bone regenerative procedures called augmentations are sometimes crucial in order to perform a successful dental procedure. Tissue engineering allows for controlled growth of alveolar and periodontal tissues, with use of scaffolds, cells, and signalling molecules. By modulating the patient's tissues, it can positively influence poor integration and healing, resulting in repeated implant surgeries. Application of nanomaterials and stem cells in tissue regeneration is a newly developing field, with great potential for maxillofacial bony defects. Nanostructured scaffolds provide a closer structural support with natural bone, while stem cells allow bony tissue regeneration in places when a certain volume of bone is crucial to perform a successful implantation. Several types of selected nanomaterials and stem cells were discussed in this study. Their use has a high impact on the efficacy of the current and future procedures, which are still challenging for medicine. There are many factors that can influence the regenerative process, while its general complexity makes the whole process even harder to control. The aim of this study was to evaluate the effectiveness and advantage of both stem cells and nanomaterials in order to better understand their function in regeneration of bone tissue in oral cavity.

The association between serum 25-hydroxyvitamin D levels and dental caries in US adults

OBJECTIVES

We investigated whether 25-hydroxyvitamin D concentration is independently associated with dental caries among adults in the United States.

SUBJECTS AND METHODS

This investigation was a cross-sectional study. A total of 4,244 participants (aged 20-80 years) were enrolled through the 2007-2008 National Health and Nutrition Examination Survey (NHANES). Serum 25-hydroxyvitamin D was categorized into four groups based on previous studies: normal (≥75 nmol/ml), insufficient (50-74.9 nmol/ml), deficient (25-49.9 nmol/ml), and severely deficient (<25 nmol/ml). The dependent and independent variables included dental caries and serum 25-hydroxyvitamin D, respectively. The data were analyzed using univariate analyses, multivariable-adjusted analyses, and subgroup analyses.

RESULTS

The fully adjusted model showed that 25-hydroxyvitamin D levels were negatively associated with dental caries after adjusting for the confounders (OR = 0.93, 95% CI 0.89 to 0.98). Compared with the normal group, the likelihood of dental caries was 2.48, 1.29, and 1.43 times higher in the severely deficient, deficient, and insufficient groups, respectively.

CONCLUSIONS

Our findings suggest that serum 25-hydroxyvitamin D levels are significantly associated with the occurrence of dental caries among US adults.

[Identification of rare diseases in the oral cavity]

In 2013, a national action plan for people with rare diseases (Nationaler Aktionsplan für Menschen mit Seltenen Erkrankungen, NAMSE) was adopted in the Federal Republic of Germany which is currently in the implementation phase. People with rare diseases are often confronted with huge difficulties in the diagnosis and therapy, and being repeatedly misdiagnosed also leads to psychological stress for those affected and their families. Of the up to 8000 rare diseases, about 15% can manifest in the orofacial region and thus give an indication of the underlying disease. A look in the oral cavity or consultative support to determine the cause of symptoms in the oral and maxillofacial region can possibly help the specialists in internal medicine to find the appropriate diagnosis.

Oral Rehabilitation of a Pediatric Patient with Vitamin D-dependent Rickets II: A Rare Case Report

Vitamin D-dependent rickets (VDDR) is a disorder of bone development characterized by softened weak bones. It is of two types-vitamin D-dependent rickets-I (VDDR-I) and vitamin D-dependent rickets type II (VDDR-II). Vitamin D-dependent rickets type II is a rare autosomal recessive disorder. The patients exhibit characteristic clinical features as well as numerous dental manifestations such as hypoplastic teeth, missing teeth, enlarged pulp chambers, and recurrent spontaneous abscesses. The case presented in this article is of vitamin D-dependent rickets type II in a pediatric dental patient who reported with multiple missing teeth and required treatment consisting of restorations and extractions. The aim of the present article is to raise awareness on the characteristics of this disorder, as well as its treatment and dental considerations.

How to cite this article

Chhonkar A, Gupta A, et al. Oral Rehabilitation of a Pediatric Patient with Vitamin D-dependent Rickets II: A Rare Case Report. Int J Clin Pediatr Dent 2019;12(1):73-75.

Prosthetic rehabilitation of a patient with X-linked hypophosphatemia using dental implants: a case report and review of the literature

BACKGROUND

X-linked hypophosphatemia is associated with a range of dental problems, many of which may result in early loss of the dentition. Most patients, but especially young adults, are likely to desire fixed prosthodontic replacements, and dental implants may be the preferred solution in many cases. The use of dental implants to rehabilitate this patient group has not been widely studied with the literature limited to a small number of case reports with limited follow-up.

CASE PRESENTATION

This case report describes the dental journey of a young adult with X-linked hypophosphatemia, his eventual tooth loss and rehabilitation with multiple dental implants. Over 10 years' follow-up of three of the fixtures is presented.

CONCLUSIONS

This case report shows a common presentation and progression of a patient with X-linked hypophosphatemia and will hopefully provide further positive evidence for the clinician to rely on when considering dental implant based treatments for such patients.

Oral symptoms and oral health-related quality of life of individuals with x-linked hypophosphatemia

Background

The primary purpose of this study was to collect data on the oral health-related quality of life (OHRQoL) of individuals with x-linked hypophosphatemia (XLH). It was also designed to gather information on the period of diagnosis, oral symptoms, orthodontic therapy, and satisfaction with dental care and the healthcare system.

Methods

A questionnaire was developed to evaluate the OHRQoL consisting of open-ended questions and the standardised German version of the Oral Health Impact Profile-14 (OHIP-14).

Results

The questionnaires from 43 participants were analysed, including 32 females (74.41%) and 11 males (25.59%). The mean OHIP-14 total score for the combined genders was 10.30 points (range: 0–37 points). For the combined genders, the mean period of time that elapsed between the first signs of the illness and the diagnosis was 5.52 years (range: 0–49 years). In total, 77.50% of the participants described oral symptoms, such as tooth mineralisation defects (n = 26), abscess or fistula formation (n = 21), dysgnathia (n = 9) and temporomandibular dysfunction (n = 2). The correlation between the participants’ satisfaction with the healthcare system and the OHIP-14 values was weak (− 0.21), and it was not statistically significant (p = 0.199).

Conclusions

The majority of the study participants reported oral involvement in the context of XLH, especially dental hard tissue mineralisation disorders, abscess formation and fistula formation. Those individuals affected by XLH with oral manifestations exhibited a tendency toward a worse OHRQoL than those without oral symptoms. In Germany, the OHIP-14 scores for these XLH patients were worse than those values that were obtained from the general population.

Electronic supplementary material

The online version of this article (10.1186/s13005-019-0192-x) contains supplementary material, which is available to authorized users.

A cross-sectional study on the association between vitamin D levels and caries in the permanent dentition of Korean children

Background

A recent study in Canada reported that vitamin D deficiency is associated with dental caries. Because Koreans have been reported to be deficient in vitamin D, we investigated the relationship between dental caries and reduced serum vitamin D levels in Korean children. The purpose of this study was to analyze the relationships between blood vitamin D [25(OH)D] concentrations and dental caries in the permanent dentition of Korean children.

Methods

Data were collected from the Korea National Health and Nutrition Examination Survey performed in 2008–2013. A total of 1688 children (10–12 years of age) were enrolled. Vitamin D intake was measured through analysis of 25-hydroxy vitamin D [25(OH)D] levels. Caries experience in permanent dentition was assessed using the decay-missing-filled teeth (DMFT) index and decayed-missing-filled (DMF) rate. Statistical analyses included complex samples Chi-square tests, complex samples logistic regression analyses, and Pearson’s correlations.

Results

The group with 25(OH) D levels lower than 50 nmol/L had a higher proportion of children with caries in the permanent dentition and permanent first molar than the group with 25(OH)D levels of 50 nmol/L or more. When external factors, such as sex, were controlled, 25(OH)D levels were not significantly correlated with caries, but were significantly correlated with first molar caries. Children with 25(OH)D levels lower than 50 nmol/L were 1.295 times more likely to have first molar caries than those with 25(OH)D levels of 50 nmol/L or more. Additionally, 25(OH)D levels and DMFT were negatively correlated; however, the degree of correlation was not strong.

Conclusions

The association between 25(OH)D and dental caries is still not clear. However, our findings suggested that vitamin D insufficiency may be a risk factor for dental caries.

Hypophosphatemic rickets: lessons from disrupted FGF23 control of phosphorus homeostasis

Fibroblast growth factor-23 (FGF23) regulates phosphate reabsorption in the kidney and therefore plays an essential role in phosphate balance in humans. There is a host of defects that ultimately lead to excess FGF23 levels and thereby cause renal phosphate wasting and hypophosphatemic rickets. We describe the genetic, pathophysiologic, and clinical aspects of this group of disorders with a focus on X-linked hypophosphatemia (XLH), the best characterized of these abnormalities. We also discuss autosomal dominant hypophosphatemic rickets (ADHR), autosomal recessive hypophosphatemic rickets (ARHR) and tumor-induced osteomalacia (TIO) in addition to other rarer FGF23-mediated conditions. We contrast the FGF23-mediated disorders with FGF23-independent hypophosphatemia, specifically hypophosphatemic rickets with hypercalciuria (HHRH). Errant diagnosis of hypophosphatemic disorders is common. This review aims to enhance the recognition and appropriate diagnosis of hypophosphatemia and to guide appropriate treatment.

Review of the dental implications of X-linked hypophosphataemic rickets (XLHR)

OBJECTIVES

The aim of this article was to review the dental implications of X-linked hypophosphataemic rickets (XLHR) and to provide suggestions regarding the dental treatment of these patients.

MATERIALS AND METHODS

The following search items "x-linked hypophosphataemia, hypophosphataemic rickets, vitamin D-resistant rickets" were used for literature search. Only full-text articles were analysed and summarized to get an overview of the different treatments and outcomes of hypophosphataemic patients.

RESULTS

Radiographically, very large pulp chambers with an abnormally high pulp volume/tooth volume ratio, suggesting taurodontism, are often evident. The affected teeth are characterised by a thin enamel layer and dentinal defects. The gender distribution of hypophosphataemic patients is almost equal, but postpubertary males seem to show a trend to develop more severe dental symptoms of the disease. Abscesses without any signs of dental caries or trauma are frequent findings. The most often affected teeth are incisors followed by molars and premolars.

CONCLUSIONS

Treatment options include frequent dental examination, application of topical fluoride varnish and sealing of pits and fissures to prevent microbial invasion that may result in pulpitis and further endodontic complications.

CLINICAL RELEVANCE

X-linked hypophosphataemic rickets is associated with marked structural alterations of dental hard tissues and the development of multiple abscesses and sinus tracts of dental origin. Therefore, profound knowledge of the various dental implications of XLHR is required to provide these patients with the best possible treatment options.

Distribution of the amelogenin protein in developing, injured and carious human teeth

Amelogenin is the major enamel matrix protein with key roles in amelogenesis. Although for many decades amelogenin was considered to be exclusively expressed by ameloblasts, more recent studies have shown that amelogenin is also expressed in other dental and no-dental cells. However, amelogenin expression in human tissues remains unclear. Here, we show that amelogenin protein is not only expressed during human embryonic development but also in pathological conditions such as carious lesions and injuries after dental cavity preparation. In developing embryonic teeth, amelogenin stage-specific expression is found in all dental epithelia cell populations but with different intensities. In the different layers of enamel matrix, waves of positive vs. negative immunostaining for amelogenin are detected suggesting that the secretion of amelogenin protein is orchestrated by a biological clock. Amelogenin is also expressed transiently in differentiating odontoblasts during predentin formation, but was absent in mature functional odontoblasts. In intact adult teeth, amelogenin was not present in dental pulp, odontoblasts, and dentin. However, in injured and carious adult human teeth amelogenin is strongly re-expressed in newly differentiated odontoblasts and is distributed in the dentinal tubuli under the lesion site. In an in vitro culture system, amelogenin is expressed preferentially in human dental pulp cells that start differentiating into odontoblast-like cells and form mineralization nodules. These data suggest that amelogenin plays important roles not only during cytodifferentiation, but also during tooth repair processes in humans.

Dental manifestations of patient with vitamin D-resistant rickets

Patients with Vitamin D-resistant rickets have abnormal tooth morphology such as thin globular dentin and enlarged pulp horns that extend into the dentino-enamel junction. Invasion of the pulp by microorganisms and toxins is inevitable. The increased fibrotic content of the pulp, together with a reduced number of odontoblasts, decreases the response to pulp infection. The most important oral findings are characterized by spontaneous gingival and dental abscesses occuring without history of trauma or caries. Radiographic examinations revealed large pulp chambers, short roots, poorly defined lamina dura and hypoplastic alveolar ridge. These dental abscesses are common and therefore the extraction and pulpectomy are the treatment of choice. The purpose of this article is to report a case of Vitamin D-resistant rickets in a 5 year-old boy, describing the dental findings and the treatment to be performed in these cases.

The rachitic tooth

Teeth are mineralized organs composed of three unique hard tissues, enamel, dentin, and cementum, and supported by the surrounding alveolar bone. Although odontogenesis differs from osteogenesis in several respects, tooth mineralization is susceptible to similar developmental failures as bone. Here we discuss conditions fitting under the umbrella of rickets, which traditionally referred to skeletal disease associated with vitamin D deficiency but has been more recently expanded to include newly identified factors involved in endocrine regulation of vitamin D, phosphate, and calcium, including phosphate-regulating endopeptidase homolog, X-linked, fibroblast growth factor 23, and dentin matrix protein 1. Systemic mineral metabolism intersects with local regulation of mineralization, and factors including tissue nonspecific alkaline phosphatase are necessary for proper mineralization, where rickets can result from loss of activity of tissue nonspecific alkaline phosphatase. Individuals suffering from rickets often bear the additional burden of a defective dentition, and transgenic mouse models have aided in understanding the nature and mechanisms involved in tooth defects, which may or may not parallel rachitic bone defects. This report reviews dental effects of the range of rachitic disorders, including discussion of etiologies of hereditary forms of rickets, a survey of resulting bone and tooth mineralization disorders, and a discussion of mechanisms, known and hypothesized, involved in the observed dental pathologies. Descriptions of human pathology are augmented by analysis of transgenic mouse models, and new interpretations are brought to bear on questions of how teeth are affected under conditions of rickets. In short, the rachitic tooth will be revealed.

Mineral and matrix changes in Brtl/+ teeth provide insights into mineralization mechanisms

The Brtl/+ mouse is a knock-in model for osteogenesis imperfecta type IV in which a Gly349Cys substitution was introduced into one COL1A1 allele. To gain insight into the changes in dentin structure and mineral composition in these transgenic mice, the objective of this study was to use microcomputed tomography (micro-CT), scanning electron microscopy (SEM), and Fourier transform infrared imaging (FTIRI) to analyze these structures at 2 and 6 months of age. Results, consistent with the dental phenotype in humans with type IV OI, showed decreased molar volume and reduced mineralized tissue volume in the teeth without changes in enamel properties. Increased acid phosphate content was noted at 2 and 6 months by FTIRI, and a trend towards altered collagen structure was noted at 2 but not 6 months in the Brtl/+ teeth. The increase in acid phosphate content suggests a delay in the mineralization process, most likely associated with the defect in the collagen structure. It appears that in the Brtl/+ teeth slow maturation of the mineralized structures allows correction of altered mineral content and acid phosphate distribution.

Clinical approach in familial hypophosphatemic rickets: report of three generations

Familial hypophosphatemic rickets is a hereditary disease characterized by the involvement of several family members, transmitted in most cases as an X-linked dominant trait. Oral manifestations can be the first evidences for an adequate and early diagnosis of X-linked hypophosphatemic rickets (XLHR). The present report describes the main systemic manifestations, oral findings and dental management in three generations of an affected family. Oral exams, laboratorial and histologic evaluations, cone-beam computed tomographies, panoramic and periapical radiographs were performed to properly institute the most adequate treatment strategy. The knowledge of clinical signs and symptoms of XLHR is essential for the correct diagnosis of this disease, and for the establishment of preventive and comprehensive dental care.

The expanding family of hypophosphatemic syndromes

Investigation of X-linked hypophosphatemia (XLH) has led to the identification of a novel phosphate-regulating homeostatic system. Initially considered vitamin D-refractory rickets, renal phosphate wasting was identified as the cardinal biochemical feature of XLH and several related disorders. Current therapy employs calcitriol and phosphate, which usually improves, but does not completely heal deformities and short stature. Later complications of XLH include development of osteophytes, entheses, and osteoarthritis. The mutated gene in XLH, PHEX, is expressed in osteocytes, but its role in the pathogenesis of phosphate wasting is poorly understood. Many hypophosphatemic disorders are mediated by FGF23, a unique fibroblast growth factor with endocrine properties. Renal action of FGF23 leads to reduced expression of type II sodium-phosphate co-transporters, as well as reduced expression of CYP27B1, which encodes vitamin D 1α-hydroxylase. FGF23-mediated hypophosphatemia is characterized by inappropriately normal circulating 1,25-dihydroxyvitamin D together with renal phosphate wasting. The FGF23 system serves as a novel mechanism by which the mineralizing skeleton can communicate phosphate supply to the kidney and thereby mediate excretion or conservation of this important skeletal component. Other forms of FGF23-mediated hypophosphatemia represent various aberrations in this axis. Secretion of excess FGF23 (as in tumor-induced osteomalacia), and mutations preventing proteolytic cleavage of FGF23 result in similar clinical features. Other hypophosphatemic disorders are discussed.

Dental Development in Patients with Hypophosphatemia Rickets

BACKGROUND

Hypophosphatemic Rickets (HR) is a disease that affects mineralized structures including bone and dentine, studies on dental development in these patients are scarce with equivocal results.

AIM

To assess dental development of a group of children with (HR) and to compare that to healthy matched controls, and to assess relationship between delayed medical treatment and dental development.

MATERIALS AND METHODS

This is a controlled cross-sectional study carried out on a sample of 21 children with HR and healthy age and sex matched controls, diseased children were diagnosed at different ages. Dental age was assessed using Demirjian et al method. The difference between ages of study and control groups was assessed using t-test, Pearson correlation was used to test relationship between age of commencement of treatment and dental development delay.

RESULTS

Most HR subjects demonstrated dental delay ranging from 0.2 to 2.5 years which was significant (p-value = 0.028). The difference between dental age of the study and control groups was statistically significant using paired t-test. There was no correlation between age of commencement of treatment and amount of dental delay.

CONCLUSION

Dental development was significantly delayed in a group of HR patients compared to matched healthy controls. Delay in commencement of treatment may lead to a permanent deficit in dental development.

Dental abnormalities and oral health in patients with Hypophosphatemic rickets

INTRODUCTION

Hypophosphatemic rickets represents a group of heritable renal disorders of phosphate characterized by hypophosphatemia, normal or low serum 1,25 (OH)2 vitamin D and calcium levels. Hypophosphatemia is associated to interglobular dentine and an enlarged pulp chambers.

AIM

Our goal was to verify the dental abnormalities and the oral health condition in these patients.

MATERIAL AND METHODS

Prospective study of oral conditions in patients with Hypophosphatemic rickets. This report employed a simple method to be easily reproducible: oral clinical exam and radiographic evaluation.

RESULTS

Fourteen patients were studied, 5 males, median age of 11 years (4 to 26). Occlusion defects (85,7%) and enamel hypoplasia (57,1%) were significant more frequently than dental abscesses (one patient). We observed enlarged pulp chambers in 43% of the patients and hypoplasia and dentin abnormalities in 14,3%. We could not detect a significant correlation between dental abnormalities and delayed treatment (p > 0,05). DMFT index for 6 to 12 years patients (n = 12) showed that the oral health is unsatisfactory (mean DMFT = 5).

CONCLUSIONS

Patients with Hypophosphatemic Rickets frequently present dental alterations and these are not completely recovered with the treatment, unless dental abscess and they need a periodical oral examination.

Oral and dental findings in osteopetrorickets

While dental findings of both rickets and osteopetrosis have been reported, there is no published report on the oral and dental findings of osteopetrorickets. In this paper dental findings of osteopetrorickets were presented. A two-year-old female child was referred to the pedodontics clinic for dental examinations before bone marrow transplantation. Her teeth showed severe mobility and the eruption of the teeth were delayed. The dental findings of the patient were different from that of osteopetrosis and rickets.

Different enamel and dentin mineralization observed in VDR deficient mouse model

Vitamin D plays an important role in the bone mineralization process. Enamel and dentin are two mineralized tissues of different origins that combine to form teeth, but the mechanism by which vitamin D regulates these tissues remains unclear. We hypothesized that vitamin D affects enamel and dentin mineralization through different mechanisms.

OBJECTIVE

To examine enamel and dentin mineralization in a vitamin D receptor (VDR) deficient mouse model by micro-computerized tomography (micro-CT) and scanning electronic microscopy (SEM).

METHODS

VDR wild type mice (VDR+/+) and VDR deficient (VDR-/-) littermates were sacrificed at 70.5 days old, and their mandibles were dissected. Micro-CT was used to compare mineral density (MD) of enamel and dentin of the two groups at different levels along the axis of mandibular incisors. SEM was employed to examine the ultrastructure of incisors at the levels corresponding to the levels used for the micro-CT studies. Furthermore, an accelerated eruption procedure was performed to exclude the effect of delayed eruption on enamel and dentin mineralization.

RESULTS

Different distribution patterns of enamel and dentin MD were observed between VDR+/+ and VDR-/- groups. Early enamel maturation, mineralization, and hypomineralization in dentin were observed in the VDR deficient mice.

CONCLUSION

Vitamin D may affect the mineralization of dentin systemically, and enamel mineralization may be regulated locally.

The genetic basis of inherited anomalies of the teeth. Part 2: syndromes with significant dental involvement

Teeth are specialized structural components of the craniofacial skeleton. Developmental defects occur either alone or in combination with other birth defects. In this paper, we review the dental anomalies in several multiple congenital anomaly (MCA) syndromes, in which the dental component is pivotal in the recognition of the phenotype and/or the molecular basis of the disorder is known. We will consider successively syndromic forms of amelogenesis imperfecta or enamel defects, dentinogenesis imperfecta (i.e. osteogenesis imperfecta) and other dentine anomalies. Focusing on dental aspects, we will review a selection of MCA syndromes associated with teeth number and/or shape anomalies. A better knowledge of the dental phenotype may contribute to an earlier diagnosis of some MCA syndromes involving teeth anomalies. They may serve as a diagnostic indicator or help confirm a syndrome diagnosis.

Vitamin D receptor deficiency affects dentin maturation in mice

Mutation of vitamin D receptors (vdr) results in resistance to the vitamin's normal effects which may compromise dentin formation. The objective of this study was to investigate the effect of vdr deficiency on post-natal dentin maturation in mice. The dentin in mandibular incisors of 70.5-day-old vdr wild-type and vdr knockout mice was compared at different levels along the long axis. Expression of biglycan and decorin was detected by immunolocalisation. Scanning electron microscopy was used to observe the ultrastructure of the dentin, and micro-computerised tomography was used to determine the degree of dentin mineralisation density. In the vdr knockout mice, the pulp chamber was larger and the dentin wall was thinner compared with the wild-type mice. In addition, the pre-dentin layer was thickened with an irregular front line and diffuse expression of biglycan and decorin. Fewer tubules, lower mineralisation density and pore-like defects were observed in the dentin at the eruptive region and level with the first molar. In conclusion, vdr deficiency compromises dentin maturation.

Bone loss and teeth

Loss of teeth results in irreversible alveolar bone resorption, and untreated dental disease causes alveolar bone lysis that ultimately leads to loss of teeth. In addition to anchoring the teeth in the alveolar ridge, the maxillary and mandibular bone allows dental restoration procedures, such as construction of root-supported implants, fixed dentures, or removable dentures. However, the functional and cosmetic results depend on the quantity and quality of the maxillary or mandibular bone, which can be affected by many normal and abnormal processes. The alveoli are particularly fragile and labile. Changes in alveolar bone vary considerably across individuals and depend directly on local factors. Many studies have investigated associations between alveolar bone status and bone mass at other skeletal sites. These studies focused chiefly on the course of parodontal disease, alveolar ridge resorption after tooth extraction, and density differences across various mandibular sites. They produced conflicting results, probably because of differences in measurement methods. Measurement sites and methods should be standardized to ensure that reliable and comparable data are obtained. To date, there are few reliable methods for obtaining quantitative measurements of bone mineral content in maxillary and mandibular bone.

Diagnosis and management of unusual dental abscesses in children

Although the majority of dental abscesses in children originate from dental caries or trauma, a few are associated with unusual conditions which challenge diagnosis and management. Recent research findings have shed light on these unusual entities and greatly improved understanding of their clinical implications. These conditions include developmental abnormalities such as dens invaginatus in which there is an invagination of dental tissues into the pulp chamber and dens evaginatus in which a tubercle containing pulp is found on the external surface of a tooth crown. In addition, inherited conditions which show abnormal dentine such as dentine dysplasia, dentinogenesis imperfecta, and osteogenesis imperfecta predispose the dentition to abscess formation. Furthermore, 'spontaneous' dental abscesses are frequently encountered in familial hypophosphataemia, also known as vitamin D-resistant rickets, in which there is hypomineralization of dentine and enlargement of the pulp. In addition to developmental conditions, there are also acquired conditions which may cause unusual dental abscesses. These include pre-eruptive intracoronal resorption which was previously known as 'pre-eruptive caries' or the 'fluoride bomb'. In addition, some undiagnosed infections associated with developing teeth are now thought to be the mandibular infected buccal cysts which originate from infection of the developing dental follicles. In the present paper, these relatively unknown entities which cause unusual abscesses in children are reviewed with the aim of updating the general practitioner in their diagnosis and management.

Oral and dental manifestations of vitamin D-dependent rickets type I: report of a pediatric case

Vitamin D-dependent rickets type I (VDDRI) represents an autosomal recessive hereditary defect in vitamin D metabolism. Patients with VDDRI have mutations of chromosome 12 that affect the gene for the enzyme 1-alpha-hydroxylase, resulting in decreased levels of 1,25(OH)(2) vitamin D. Clinical features include growth failure, hypotonia, weakness, rachitic rosary, convulsions, tetany, open fontanels, and pathologic fractures. The oral and dental manifestations of VDDRI have not been described. Here we present the case of a 10-year-old girl affected by VDDRI, as established by the combination of clinical and radiographic findings, family history, and laboratory values. Dental examination revealed markedly hypoplastic, yellowish-to-brownish enamel in all permanent teeth, malocclusion, and chronic periodontal disease. Large quadrangular pulp chambers and short roots were evident in dental radiographs. Light microscopic and ultrastructural examination showed abnormalities of dental hard tissues, affecting both enamel and dentin. The differential diagnosis and treatment of VDDRI are discussed.

Dental abnormalities in patients with familial hypophosphatemic vitamin D-resistant rickets: prevention by early treatment with 1-hydroxyvitamin D

OBJECTIVE

To evaluate the dental effects of 1-hydroxylated vitamin D3 treatment in patients with familial hypophosphatemic vitamin D-resistant rickets. Study design Forty-eight children and adult patients were included in the study; 16 had received no treatment or phosphate supplements with vitamin D/25-(OH) D3 before puberty. The 32 younger ones had received phosphate supplements with 1alpha-(OH)D3 from infancy. All patients were clinically examined, and panoramic and periapical radiographs were made. Evaluations of decayed, missing, or filled teeth and decayed or filled teeth indexes and of pulp ratios allowed comparison with healthy age-matched control patients.

RESULTS

Poor dental health and characteristic dental anomalies were found in the 16 older patients. In contrast, the 32 younger patients had a normal dental status as regards reference ranges in healthy age-matched populations, although they still showed prominent pulp horns on deciduous teeth and increased pulp area/tooth area ratios.

CONCLUSIONS

This investigation shows the beneficial effects of 1alpha-(OH)D3 treatment on the dental status of vitamin D-resistant rickets patients and emphasizes the necessity of early treatment. Remaining defects may result from early exposure of odontoblasts and surrounding osteoblasts to hypophosphatemia, before the commencement of treatment, and/or from intrinsic cell disturbances linked to the genetic alteration(s).