Periodontal status of patients with hypophosphatemic rickets: a case series

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.

Sclerostin antibody improves alveolar bone quality in the Hyp mouse model of X-Linked Hypophosphatemia (XLH)

X-linked hypophosphatemia (XLH) is a rare disease of elevated fibroblast growth factor 23 (FGF23) production that leads to hypophosphatemia and poor mineralization of bone and teeth. The clinical manifestations of XLH include a high prevalence of dental abscesses, likely driven by poorly formed structures of the dentoalveolar complex, including the alveolar bone, cementum, dentin, and periodontal ligament. Our previous studies have demonstrated that sclerostin antibody (Scl-Ab) treatment improves phosphate homeostasis, and increases bone mass, strength and mineralization in the Hyp mouse model of XLH. In the current study, we investigated whether Scl-Ab impacts the dentoalveolar structures of Hyp mice. Male and female wild-type and Hyp littermates were injected with 25 mg/kg of vehicle or Scl-Ab twice weekly beginning at 12 weeks of age and euthanized at 20 weeks of age. Scl-Ab increased alveolar bone mass in both male and female mice and alveolar tissue mineral density in the male mice. The positive effects of Scl-Ab were consistent with an increase in the fraction of active (non-phosphorylated) β-catenin stained alveolar osteocytes. Scl-Ab had no effect on mineralized tissues of the tooth - dentin, enamel, acellular and cellular cementum. There was a non-significant trend toward increased periodontal ligament (PDL) attachment fraction within the Hyp mice. Additional PDL fibral structural parameters were not affected by Scl-Ab. The current study demonstrates that Scl-Ab can improve alveolar bone in the Hyp mouse model of XLH.

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.

Dental health of patients with X-linked hypophosphatemia: A controlled study

Objective

The present study compared the dental health of patients with X-linked hypophosphatemia (XLH) with healthy age- and gender-matched controls to increase our knowledge of the impact of XLH on oral health.

Materials and methods

Twenty-two adult patients with XLH in the Stockholm region of Sweden were referred to the Department of Orofacial Medicine at Karolinska Institutet for an extended clinical and radiological examination. Pre-existing radiologic examinations of 44 healthy age- and gender-matched controls were retrieved from the Department of Oral Radiology, at Karolinska Institutet.

Results

The 22 patients with XLH (15 females, median age 38 years, range 20-71; 7 males, median age 49 years, range 24-67) had a significantly higher number of root-filled teeth compared to healthy controls (p = .001). In the XLH group, females had significantly better oral health than males, especially concerning endodontic and cariological status (p's = .01 and .02, respectively). Periodontal status differed non-significantly between the XLH and control groups.

Conclusion

Patients with XLH had a significantly lower oral health status compared to a healthy population especially concerning endodontic conditions. Male patients with XLH had a higher risk of poor oral health compared to female patients with XLH.

Effect of conventional treatment on dental complications and ectopic ossifications among 30 adults with XLH

CONTEXT

Conventional treatment of XLH was reported to prevent dental complications, but whether the preventive effect was different among different types of teeth, including anterior teeth and molar teeth, is uncertain. Evidence of the preventive effect of conventional treatment on ectopic ossifications is also limited.

OBJECTIVE

To compare dental complications and ectopic ossifications among XLH adults with early (< 5 years old) or late (≥5 years old) conventional treatment.

METHODS

This retrospective observational study included a total of 30 adults with XLH using orthopantomograms, spinal computed tomography scans and X-rays of hip/knee joints. Dental complications, including decayed, missing filled (DMF) index and devitalized tooth, apical periodontitis, and periodontitis, were evaluated. The index of ossification of the anterior/posterior longitudinal ligament and yellow ligament (OA/OP/OY index) and the sum of the OA/OP/OY index (OS index) were utilized to evaluate the severity of spinal ligament ossification. The severity of the hip/knee osteophytes was evaluated by the Kellgren-Lawrence (KL) classification.

RESULTS

The number of sound teeth was significantly lower, and the DMF index was significantly higher in patients with late treatment. The severity of dental complications in the anterior tooth and molar tooth, OA/OP/OY/OS index, and KL grade were not significantly different among patients with early treatment and those with late treatment.

CONCLUSION

Early treatment could prevent dental complications but did not prevent ectopic ossification in adult patients with XLH. The difference in the preventive effect was not observed among different types of teeth.

Adult Presentation of X-Linked Hypophosphatemia

Adult X-linked hypophosphatemia (XLH) patients present with specific symptoms, including enthesopathies (e.g., ossification of longitudinal ligaments (OPLL), osteophytes around large joints, and enthesopathy in the Achilles tendons), early osteoarthritis, the development of severe secondary and tertiary hyperparathyroidism (SHPT/THPT), and the subsequent progression of chronic kidney disease (CKD). In addition, these patients exhibit the typical phenotypes of osteomalacia, such as pseudofracture and fracture in weight-bearing bones, odontitis, and tooth abscesses. The mechanism underlying enthesopathy development is unknown; however, a common underlying mechanism among XLH and autosomal recessive hypophosphatemic rickets (ARHR1/2) due to mutations in PHEX, DMP1, and ENPP1 is assumed. Clarification of the pathogenesis and drug discovery for this complication is an urgent issue, as many adult XLH patients suffer subsequent debilitating nervous symptoms or impingement syndrome, and existing treatments are ineffective. Severe SHPT and THPT are associated with conventional therapy, including active vitamin D and phosphate supplementation, and complicated and careful adjustment of dosages by experienced clinicians is required to avoid SHPT/THPT. Burosumab is a very effective therapy without risk for the development of SHPT/THPT. However, indications for this drug should be carefully considered, along with cost-effectiveness, guidelines or recommendations, and the health care system of each country.

X-linked hypophosphatemic rickets: Orthodontic considerations and management. A case report

X-linked hypophosphatemic rickets (XLH) is a rare condition affecting bone metabolism. It has characteristic dental features such as poorly mineralised dentine, spontaneous abscess formation in the absence of caries and taurodontism. There are limited published data about patients with this condition undergoing orthodontic treatment, and there is no clear guideline on the suitability of orthodontic treatment in this cohort. We present a case report of a patient with XLH with a confirmed PHEX gene mutation undergoing orthodontic treatment and clinical recommendations to support treatment.

Rare Genetic Disorders Affecting the Periodontal Supporting Tissues in Adolescence

In adolescents periodontal destruction may be the primary manifestation of an as yet unrecognized rare systemic disease, and it may be up to the periodontist to make the correct tentative diagnosis. Many genetic diseases that present with primary periodontal manifestations in adolescence affect immune function, sometimes with only mild or absent systemic features. They include periodontal Ehlers-Danlos syndrome (lack of attached gingiva, various connective tissue abnormalities), Papillon-Lefèvre syndrome (palmoplantar hyperkeratosis), and plasminogen deficiency (fibrin deposition within mucous membranes). Other immune disorders with severe periodontitis manifesting in adolescence are usually diagnosed in early childhood due to unmistakeable systemic features. They include Cohen syndrome (developmental disorder, truncal obesity, and microcephaly), Hermansky-Pudlak Syndrome (oculocutaneous albinism, bleeding diathesis, and other systemic manifestations), glycogen storage disease type 1b, and Chediak-Higashi syndrome (pyogenic infections, albinism, and neuropathy). The structural integrity of periodontal tissue is affected in genodermatoses such as Kindler syndrome, a type of epidermolysis bullosa. In primary hyperoxaluria, inflammatory periodontal destruction is associated with renal calculi. Breakdown of periodontal tissues independent of dental plaque biofilm-induced periodontitis is found in hypophosphatasia (highly variable skeletal hypomineralization) or isolated odontohypophosphatasia, hypophosphatemic rickets and primary hyperparathyroidism. Finally, alveolar osteolysis mimicking localized periodontitis may be due to neoplastic processes, e.g., in neurofibromatosis type 1 (typical skin features including café au lait macules and neurofibromas), Langerhans cell histiocytosis (locally destructive proliferation of bone marrow-derived immature myeloid dendritic cells), and Gorham-Stout disease (diffuse cystic angiomatosis of bone).

Clinical practice recommendations for the diagnosis and management of X-linked hypophosphataemia

X-linked hypophosphataemia (XLH) is the most common cause of inherited phosphate wasting and is associated with severe complications such as rickets, lower limb deformities, pain, poor mineralization of the teeth and disproportionate short stature in children as well as hyperparathyroidism, osteomalacia, enthesopathies, osteoarthritis and pseudofractures in adults. The characteristics and severity of XLH vary between patients. Because of its rarity, the diagnosis and specific treatment of XLH are frequently delayed, which has a detrimental effect on patient outcomes. In this Evidence-Based Guideline, we recommend that the diagnosis of XLH is based on signs of rickets and/or osteomalacia in association with hypophosphataemia and renal phosphate wasting in the absence of vitamin D or calcium deficiency. Whenever possible, the diagnosis should be confirmed by molecular genetic analysis or measurement of levels of fibroblast growth factor 23 (FGF23) before treatment. Owing to the multisystemic nature of the disease, patients should be seen regularly by multidisciplinary teams organized by a metabolic bone disease expert. In this article, we summarize the current evidence and provide recommendations on features of the disease, including new treatment modalities, to improve knowledge and provide guidance for diagnosis and multidisciplinary care.

Tissue-specific mineralization defects in the periodontium of the Hyp mouse model of X-linked hypophosphatemia

X-linked hypophosphatemia (XLH) is a dento-osseous disorder caused by inactivating mutations in the PHEX gene, leading to renal phosphate wasting and hypophosphatemia, and impaired mineralization of bones and teeth. In the oral cavity, recent reports suggest a higher susceptibility of XLH patients to periodontitis, where patients present with impaired tooth cementum - a bone-like tissue involved in tooth attachment to the jaw bones and post-eruption tooth positioning - and a higher frequency of intrabony defects. In the present study, the pathobiology of alveolar bone and tooth cementum was investigated in the Hyp mouse, the murine analog of XLH. PHEX deficiency in XLH/Hyp dramatically alters the periodontal phenotype, with hypoplasia of tooth root cementum associated with a lack of periodontal ligament attachment and the presence of an immature apatitic mineral phase of all periodontal mineralized tissues. Challenging the Hyp periodontium in two surgical experimental models - ligature-induced periodontal breakdown and repair, and a model of tooth movement adaptation inducing cementum formation - we show that bone and cementum formation, and their healing, are altered. Bone and cementum mineralization appear similarly disturbed, where hypomineralized pericellular matrix surrounds cells, and where the protein osteopontin (OPN, a mineralization inhibitor) accumulates in a tissue-specific manner, most notably in the perilacunar matrix surrounding osteocytes. Although the pathobiology is different between XLH/Hyp bone and cementum, our results show a major XLH phenotype in oral mineralized tissues consistent with variations in patient susceptibility to periodontal disorders.

Phosphate and Vitamin D Prevent Periodontitis in X-Linked Hypophosphatemia

X-linked hypophosphatemia (XLH) is a rare genetic skeletal disease where increased phosphate wasting in the kidney leads to hypophosphatemia and prevents normal mineralization of bone and dentin. Here, we examined the periodontal status of 34 adults with XLH and separated them according to the treatment they received for hypophosphatemia. We observed that periodontitis frequency and severity were increased in adults with XLH and that the severity varied according to the hypophosphatemia treatment. Patients who benefited from an early and continuous vitamin D and phosphate supplementation during their childhood presented less periodontal attachment loss than patients with late or incomplete supplementation. Continued hypophosphatemia treatment during adulthood further improved the periodontal health. Extracted teeth from patients with late or incomplete supplementation showed a strong acellular cementum hypoplasia when compared with age-matched healthy controls. These results show that XLH disturbs not only bone and dentin formation but also cementum and that the constitutional defect of the attachment apparatus is associated with attachment loss.

Therapeutic management of hypophosphatemic rickets from infancy to adulthood

In children, hypophosphatemic rickets (HR) is revealed by delayed walking, waddling gait, leg bowing, enlarged cartilages, bone pain, craniostenosis, spontaneous dental abscesses, and growth failure. If undiagnosed during childhood, patients with hypophosphatemia present with bone and/or joint pain, fractures, mineralization defects such as osteomalacia, entesopathy, severe dental anomalies, hearing loss, and fatigue. Healing rickets is the initial endpoint of treatment in children. Therapy aims at counteracting consequences of FGF23 excess, i.e. oral phosphorus supplementation with multiple daily intakes to compensate for renal phosphate wasting and active vitamin D analogs (alfacalcidol or calcitriol) to counter the 1,25-diOH-vitamin D deficiency. Corrective surgeries for residual leg bowing at the end of growth are occasionally performed. In absence of consensus regarding indications of the treatment in adults, it is generally accepted that medical treatment should be reinitiated (or maintained) in symptomatic patients to reduce pain, which may be due to bone microfractures and/or osteomalacia. In addition to the conventional treatment, optimal care of symptomatic patients requires pharmacological and non-pharmacological management of pain and joint stiffness, through appropriated rehabilitation. Much attention should be given to the dental and periodontal manifestations of HR. Besides vitamin D analogs and phosphate supplements that improve tooth mineralization, rigorous oral hygiene, active endodontic treatment of root abscesses and preventive protection of teeth surfaces are recommended. Current outcomes of this therapy are still not optimal, and therapies targeting the pathophysiology of the disease, i.e. FGF23 excess, are desirable. In this review, medical, dental, surgical, and contributions of various expertises to the treatment of HR are described, with an effort to highlight the importance of coordinated care.

Extracellular matrix mineralization in periodontal tissues: Noncollagenous matrix proteins, enzymes, and relationship to hypophosphatasia and X-linked hypophosphatemia

As broadly demonstrated for the formation of a functional skeleton, proper mineralization of periodontal alveolar bone and teeth - where calcium phosphate crystals are deposited and grow within an extracellular matrix - is essential for dental function. Mineralization defects in tooth dentin and cementum of the periodontium invariably lead to a weak (soft or brittle) dentition in which teeth become loose and prone to infection and are lost prematurely. Mineralization of the extremities of periodontal ligament fibers (Sharpey's fibers) where they insert into tooth cementum and alveolar bone is also essential for the function of the tooth-suspensory apparatus in occlusion and mastication. Molecular determinants of mineralization in these tissues include mineral ion concentrations (phosphate and calcium), pyrophosphate, small integrin-binding ligand N-linked glycoproteins and matrix vesicles. Amongst the enzymes important in regulating these mineralization determinants, two are discussed at length here, with clinical examples given, namely tissue-nonspecific alkaline phosphatase and phosphate-regulating gene with homologies to endopeptidases on the X chromosome. Inactivating mutations in these enzymes in humans and in mouse models lead to the soft bones and teeth characteristic of hypophosphatasia and X-linked hypophosphatemia, respectively, where the levels of local and systemic circulating mineralization determinants are perturbed. In X-linked hypophosphatemia, in addition to renal phosphate wasting causing low circulating phosphate levels, phosphorylated mineralization-regulating small integrin-binding ligand N-linked glycoproteins, such as matrix extracellular phosphoglycoprotein and osteopontin, and the phosphorylated peptides proteolytically released from them, such as the acidic serine- and aspartate-rich-motif peptide, may accumulate locally to impair mineralization in this disease.

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.