Craniofacial and dental characteristics of patients with vitamin-D-dependent rickets type 1A compared to controls and patients with X-linked hypophosphatemia

Characteristics of oral health of patients with X-linked hypophosphatemia: case reports and literature review

BACKGROUND

Oral health is impaired in X-linked hypophosphatemia (XLH), resulting in delayed dental development, malocclusion, and radiographic abnormalities. This study investigates the oral manifestations in Slovenian XLH patients, focusing on enamel and dentin abnormalities and a literature review of spontaneous periapical abscesses in XLH cases.

OBJECTIVES

To report XLH patients with specific oral signs and symptoms, histological analysis of affected teeth, and review of reported cases of XLH patients with spontaneous periapical abscesses.

METHODS

Case reports: Seven XLH patients from the National Registry of Patients with Rare Diseases underwent a detailed oral examination, including X-ray reviews. The patients who were expected to have tooth exfoliation or extraction were asked to donate their teeth for histological analysis by scanning electron microscopy.

LITERATURE SEARCH

A literature search of four electronic databases and a manual bibliography search aimed to identify documented cases of XLH with periapical abscesses up to January 21, 2024. Inclusion criteria were confirmed XLH patients with periapical abscesses in English peer-reviewed publications.

RESULTS

Tooth samples from three XLH patients showed reduced dentin mineralisation, affecting one-third to one-half of the outer dentin. Inadequate mineralisation, uneven dentin tubules, and cracks and chipping in the enamel were observed, indicating mineralisation deviations. Similar cracks extended into the dentin and were also present in the root of the examined tooth. Based on the content of the 75 items identified in the search, spontaneous abscesses are not uncommon in patients with XLH.

CONCLUSIONS

XLH significantly affects patients' lives and requires lifelong treatment. Dental examinations consistently revealed oral problems, including malocclusion. Histological analysis confirmed structural changes, especially in the dentin. Despite continued treatment, XLH patients may have an increased risk of oral pathologies. Further research is needed to understand the impact of XLH and its treatment on dental health.

Orthodontic treatment in children and adolescent patients with X-linked hypophosphatemia: A case-control study

OBJECTIVES

X-linked hypophosphatemia (XLH) is a rare genetic disease that disturbs bone and teeth mineralization. It also affects craniofacial growth and patients with XLH often require orthodontic treatment. The aim of this study was to describe changes in the dental health of XLH children during orthodontic treatment compared with those in matched controls undergoing similar orthodontic procedures.

MATERIALS AND METHODS

For this retrospective case-control study, we included all individuals less than 16 years old diagnosed with XLH, orthodontically treated in our centre from 2016 to 2022 and pair-matched them to patients with no chronic or genetic conditions. Clinical and radiological parameters concerning their malocclusion, craniofacial discrepancy and the characteristics and iatrogenic effects of their orthodontic treatment were analysed.

RESULTS

Fifteen XLH patients (mean age: 11.3 ± 2.1), pair-matched to 15 control patients were included. Orthodontic treatment was successfully conducted in XLH patients with slightly shorter duration and similar iatrogenic effects as in the control group, except for the occurrence of dental abscess during and after orthodontic tooth movement. XLH patients did not show more relapse than the controls.

CONCLUSION

Despite the presence of oral manifestations of XLH such as spontaneous abscesses, XLH patients can undergo orthodontic treatment with no obvious additional iatrogenic effects.

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.

Vitamin D Hydroxylation-deficient Rickets Type 1A Misdiagnosed as Normocalcemic Primary Hyperparathyroidism

Vitamin D hydroxylation-deficient rickets type 1A is an autosomal recessive disorder caused by pathogenic variants in CYP27B1 gene, which encodes for 1α-hydroxylase, the enzyme responsible for the conversion of 25-OH vitamin D into its active form 1,25(OH)2 vitamin D. We report the case of a 3-year-old female Mexican patient with growth retardation and progressive bone deformity, whose laboratory studies showed 25-OH vitamin D deficiency, a normal serum calcium and an elevated intact parathyroid hormone level that remained high despite calcitriol, cholecalciferol, and calcium supplementation. 99mTc sestamibi gammagram showed findings suggestive of parathyroid hyperplasia. Bone histomorphometry showed an image consistent with hyperparathyroidism without findings of osteomalacia, so normocalcemic primary hyperparathyroidism was suspected and a subtotal parathyroidectomy was performed, with the patient developing postoperative hypoparathyroidism. When she arrived at our clinic at age 18 years, she showed calcium- and calcitriol-dependent hypocalcemia, with secondary hyperparathyroidism and low levels of 1,25(OH)2 vitamin D in the absence of a 25-OH vitamin D deficiency, reflecting a defect in 1α-hydroxylation. Molecular testing revealed compound heterozygous variants in CYP27B1 gene. This is the first reported case of an inherited disorder of vitamin D metabolism that was diagnosed and surgically treated as primary hyperparathyroidism.

Congenital Conditions of Hypophosphatemia in Children

Great strides over the past few decades have increased our understanding of the pathophysiology of hypophosphatemic disorders. Phosphate is critically important to a variety of physiologic processes, including skeletal growth, development and mineralization, as well as DNA, RNA, phospholipids, and signaling pathways. Consequently, hypophosphatemic disorders have effects on multiple systems, and may cause a variety of nonspecific signs and symptoms. The acute effects of hypophosphatemia include neuromuscular symptoms and compromise. However, the dominant effects of chronic hypophosphatemia are the effects on musculoskeletal function including rickets, osteomalacia and impaired growth during childhood. While the most common causes of chronic hypophosphatemia in children are congenital, some acquired conditions also result in hypophosphatemia during childhood through a variety of mechanisms. Improved understanding of the pathophysiology of these congenital conditions has led to novel therapeutic approaches. This article will review the pathophysiologic causes of congenital hypophosphatemia, their clinical consequences and medical therapy.

Long-term dental intervention and laboratory examination in a patient with Vitamin D-dependent rickets type I: A case report

RATIONALE

Vitamin D-dependent rickets type I (VDDR-I) is a rare form of rickets, which is an autosomal recessive disease caused by 1α-hydroxylase enzyme deficiency. However, long-term dental management and microscopic morphology of teeth remain largely unclear.

PATIENT CONCERNS

We report the case of a 10-year-old Chinese boy complaining of yellowish-brown teeth with extensive caries.

DIAGNOSES

Clinical and laboratory examinations were performed, and VDDR-I was confirmed. Scanning electron microscopy confirmed amelogenesis imperfecta.

INTERVENTIONS

The patient had been taking drugs intervention for VDDR-I from the age of 3 years. The decayed teeth were treated, and metal-preformed crowns were placed to prevent further impairment. Sequence tooth extraction and remineralization therapy were also performed.

OUTCOMES

After 3 years of follow-up, the patient exhibited normal tooth replacement and an acceptable oral hygiene status. However, the new erupted teeth had amelogenesis imperfecta.

LESSONS

This case is the first to confirm amelogenesis imperfecta in a patient with VDDR-I that was not prevented by drug intervention. Importantly, it provides evidence that long-term dental intervention in patients with VDDR-I can result in an acceptable oral hygiene status. Therefore, early and long-term dental intervention is necessary in VDDR-I patients.

Dentoalveolar Defects in the Hyp Mouse Model of X-linked Hypophosphatemia

Mutations in PHEX cause X-linked hypophosphatemia (XLH), a form of hypophosphatemic rickets. Hyp (Phex mutant) mice recapitulate the XLH phenotype. Dental disorders are prevalent in individuals with XLH; however, underlying dentoalveolar defects remain incompletely understood. We analyzed Hyp mouse dentoalveolar defects at 42 and 90 d postnatal to comparatively define effects of XLH on dental formation and function. Phex mRNA was expressed by odontoblasts (dentin), osteocytes (bone), and cementocytes (cellular cementum) in wild-type (WT) mice. Enamel density was unaffected, though enamel volume was significantly reduced in Hyp mice. Dentin defects in Hyp molars were indicated histologically by wide predentin, thin dentin, and extensive interglobular dentin, confirming micro-computed tomography (micro-CT) findings of reduced dentin volume and density. Acellular cementum was thin and showed periodontal ligament detachment. Mechanical testing indicated dramatically altered periodontal mechanical properties in Hyp versus WT mice. Hyp mandibles demonstrated expanded alveolar bone with accumulation of osteoid, and micro-CT confirmed decreased bone volume fraction and alveolar bone density. Cellular cementum area was significantly increased in Hyp versus WT molars owing to accumulation of hypomineralized cementoid. Histology, scanning electron microscopy, and nanoindentation revealed hypomineralized "halos" surrounding Hyp cementocyte and osteocyte lacunae. Three-dimensional micro-CT analyses confirmed larger cementocyte/osteocyte lacunae and significantly reduced perilacunar mineral density. While long bone and alveolar bone osteocytes in Hyp mice overexpressed fibroblast growth factor 23 (Fgf23), its expression in molars was much lower, with cementocyte Fgf23 expression particularly low. Expression and distribution of other selected markers were disturbed in Hyp versus WT long bone, alveolar bone, and cementum, including osteocyte/cementocyte marker dentin matrix protein 1 (Dmp1). This study reports for the first time a quantitative analysis of the Hyp mouse dentoalveolar phenotype, including all mineralized tissues. Novel insights into cellular cementum provide evidence for a role for cementocytes in perilacunar mineralization and cementum biology.

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.