A child with x linked
hypophosphatemia with OSA symptoms referred for orthodontics intervention. What are the important issues for the dental team?
Definition:
x-linked hypophosphatemia is the most common hereditary form of
hypophosphatemic rickets. The child will present with rickets due to renal
phosphate wasting and reduction of intestinal absorption of phosphate and calcium
with the diminish production of 1,25‐(OH)2 vitamin D.
The child may look like this:
Issues
Preoperative
a)Complications
from XLH if poorly controlled
1 1. Open bite/ OSA requiring
orthognathic surgery
-Delay in maxillary growth in relation to the growth of the
mandible with skeletal class III tendency.
2.
Delayed bone healing
- Impaired bone
remodelling with lack of bone mineralization in XLH
-Possibility of
bisphosphonate use? Risk of BRONJ post op?
3. Spontaneous dental abscesses
-
IN XLH, the teeth exhibit
enlarged pulp chambers with fissures that linked the enamel subsurface to the
pulp horn due to globular dentin caused by hypophosphatemia which impairs
calcification. Thus, the teeth are prone to develop dental abscesses requiring
endodontic treatment.
-
Prevent by application of
self-etching flowable composite sealants on teeth
-
It can happen during
orthodontic treatment if, there is undesired heavy forces → pulp hyperemia →
pulpitis → transient apical breakdown with periapical lesion (still reversible
through revitalization) → pulp necrosis → apical periodontitis.
4. Periodontal disease
-
Prior to starting orthodontic treatment,
the periodontal health of the dentition should be established. There is
increased risk of periodontal disease with severe attachment loss due to
cementum aplasia or hypoplasia in XLH.
5. Bone/joint pain due to
osteomalacia, insufficiency fractures and osteoarthritis
-
They might be on long term NSAIDS. Thus,
to check prior to prescribing analgesics
-
May affect TMJ?
6. Hearing difficulties with
mild-to-severe sensorineural hearing loss. Some patients also present with tinnitus and vertigo
-
Ensure patient is clear on risks of
procedure (informed consent). Additionally, patient may be having high risk of
falls in the ward if patient presents with vertigo.
b) We can assess Compliance
to treatment by:
-Maintenance of acceptable height velocity and improvement in
skeletal deformities generally indicate satisfactory dosing. Be aware that normalization
of the serum phosphate is not what we are looking for as this can lead to
secondary hyperparathyroidism.
c) Complication of
treatment (Calcitriol)
-If
overtreated, it can cause nephrocalcinosis (polyuria leading to dehydration).
Thus, a renal profile with plasma calcium, PTH, creatinine and 24-h urinary
calcium excretion is required
- Patient may have hypercalcemia with features
of kidney or biliary stones, bone pain, groans (abdominal
pain, nausea and vomiting).
Perioperative
1. Risk of spinal cord
stenosis leading to weakness/paralysis of upper and/or lower limbs
-During
intubation, a prolonged hyperextension of the cervical spine can lead to
compression of the spinal cord.
-Those
who have X-linked hypophosphatemic rickets are at higher risk of this due to
thickening of the vertebral laminae, facet joint hypertrophy, and ossification
of the intervertebral discs, posterior longitudinal ligament, and/or ligamentum
flavum.
2. Risk of bone
fractures
-
Unfavourable bone
fracture during orthognathic due to osteoporosis
Postoperative
Monitor vital signs (Pulse rate, spo2, respiratory rate, gcs)
-Severe
hypophosphatemia may cause myocardial dysfunction, ventricular arrhythmias, rhabdomyolysis,
seizures and altered mental status. They will first complain of skeletal muscle
weakness particularly respiratory muscle.
