X-linked hypophosphatemia (XLH) was first described by Albright  as Vitamin D-resistant rickets and is the most common hereditary metabolic rickets with a prevalence of 1:20,000 . The genetic mutation is of the phosphate-regulating gene PHEX which results in reduced phosphate reabsorption by the kidneys  and due to the dependency between calcium and phosphate homeostasis results in bone deformities (particularly bowing of the lower extremities), bone pain, reduced growth, hypophosphatemia, inappropriately normal serum 1,25(OH)2D levels and phosphate wasting . There is a general lack of information about XLH and treatment guidelines which frequently lead to missed diagnoses and mismanagement .
The dental implications of XLH manifest clinically as recurrent abscess and sinus tract formation associated with non-carious teeth [6,7,8,9,10,11,12,13,14,15,16,17,18,19] as well as delayed tooth eruption [12, 19] in both the primary and in the permanent dentitions. Edentulous regions generally have hypoplastic alveolar ridges [17, 20]. Radiographic appearance is classically of large pulp chambers [6, 8, 10,11,12,13,14, 17,18,19,20,21,22,23] with a high pulp-to-tooth volume ratio (taurodontism) [6, 8, 9, 12, 16]. A thin enamel layer [6, 8, 10, 18, 20, 21, 23] along with dentinal defects [6, 8, 18, 20, 23, 24], short roots [11, 20, 23], root resorptions in the primary dentition [16, 20, 22], a poorly defined lamina dura [10, 16, 17, 20] and an increase in the prevalence and severity of periodontal disease  are also seen.
Histologically, the dentine is characterised by large tubular clefts or lacunae [9, 17, 23] with prominent pulp horns [7, 8, 10, 13, 16, 17, 19, 21, 22, 26] often extending up to and beyond the amelo-dentinal junction (ADJ) [6,7,8,9,10, 13, 16, 17, 19, 21, 22] particularly in the primary teeth [8, 10, 11, 19, 22, 27,28,29]. The dentine layer is usually thin [8, 30] and with areas of unmineralised dentine [6, 10, 16, 18, 21, 23, 30,31,32], a wide predentine zone and tubular defects [6, 10, 13, 23, 24]. This appearance is due to a lack of fusion of calcospherites and consequently the presence of large interglobular spaces [7, 22, 24]. There is also a lack of secondary dentine formation .
There is an acellular cementum hypoplasia especially in patients with late or incomplete supplement treatment . The enamel is hypoplastic and presents with cracks extending from the surface to the ADJ [9, 10, 12, 14, 18, 21, 23, 34]. It is these enamel cracks along with the dentinal defects described which allow microbial penetration into the pulp chamber resulting in the clinical presentation seen .
Older patients with XLH have more experience of dental abscesses , and the most frequently affected teeth are incisors and canines followed by the molars . This pattern of presentation is thought to be due to both the sequence of eruption and also the rate of attrition exposing defective dentine to microbial invasion [10, 17, 24].
Medical treatment for XLH usually consists of oral phosphate supplements and calcitriol. This aims to reduce the hypophosphatemia but prevents the development of secondary hyperparathyroidism . Systemic treatment has been shown to prevent or treat dental anomalies by some authors [8, 19, 25, 36], but others have found little dental benefit [8, 14, 37, 38].
Due to the wide variety of dental presentations, there is no consensus on the most appropriate treatment modality . The most commonly agreed upon recommendations are regular dental review including sensitivity testing of all teeth and radiographic examination of the entire dentition .
There is a dearth of literature on the use of dental implants in patients diagnosed with XLH consisting of a handful of case reports with short follow-up. Considering the likelihood that young patients with multiple missing teeth and rapidly failing dentitions will desire fixed rehabilitations, implant-supported prosthesis may be the preferred treatment modality. The aim of this paper is to provide long term evidence that implant-supported prostheses can be successful in this patient group and give the clinician considering such an approach confidence by reporting a case of a young patient with XLH who has been rehabilitated with four dental implant-supported restorations, utilising five fixtures, and a follow-up of 1 year 9 months to 10 years 3 months.