4 The patient is also concerned about persistent pain from the #15 and wants it extracted at the same appointment. What risk is associated with the propylthiouracil medication?Propylthiouracil has anti‐vitamin K activity and can cause hypoprothrombinaemia, leading to an increased risk of bleedingFurthermore, it is a thionamide and hence may cause a rare reaction of agranulocytosis (0.5% of patients) that can result in oral infections and inadequate wound healing
5 What additional risks associated with hyperthyroidism should be considered when planning extraction of the #15?The patient's hyperthyroidism is unlikely to be controlled as the diagnosis/treatment was relatively recent; it is preferable to consider initial pain/infection control using medication until the physician confirms the patient is stableHeightened patient anxiety and irritability likelyElevated blood pressure and heart rate due to the effects of thyroid hormone on sympathetic nervous system activityPatients with high arteriolar pressures may also require increased attention and a longer duration of local pressure to stop bleedingSympathetic overactivity may lead to faintingA thyroid storm may be provoked during dental treatment by the stress, administration of epinephrine, infection or traumatic surgery
6 What other factors do you need to consider in your risk assessment?SocialReliance on daughter (who works as a school teacher) for transport/to attend appointmentsMedicalRisk of cardiac arrythmiasAdditional bleeding risk associated with dabigatran (see Chapter 10.4)Gastro‐oesophageal reflux disease may be associated with positional limitationsDentalPoor oral health and irregular attenderAdvanced tooth surface lossPartially edentateOsteoporotic changes in the jaw bone secondary to hyperthyroidism
7 The patient requests dental implants to replace the missing teeth. What are the associated risks you should discuss?Poor oral health needs to be stabilised firstCompliance and need for regular dental visits and maintenanceBleeding riskInfection riskOsteoporotic changes in the mandible
General Dental Considerations
Oral Findings
Early tooth eruption and exfoliation of primary teeth
Alveolar bone osteoporosis
Increased caries and periodontal disease (due to high sugar intake to satisfy caloric requirement)
Ectopic thyroid tissue located on the foramen caecum of the tongue is called lingual thyroid, and in some cases may be the only active thyroid tissue present
Propylthiouracil/carbamizole may cause agranulocytosis, which may result in oral or oropharyngeal ulceration
Dental Management
Treatment should be modified based on the severity of the condition, the medical management in place and the invasiveness of the proposed dental intervention (Table 5.3.1)Table 5.3.1 Dental management considerations.Risk assessmentThese patients may have heightened anxiety and irritabilitySympathetic overactivity may lead to faintingA thyroid storm may be provoked during dental treatment by the stress, or by epinephrine, infection or traumatic surgeryBleeding tendency in patients on propylthiouracilRisk of lymphopenia in patients on propylthiouracilCarbimazole occasionally leads to agranulocytosis, which may cause oral or oropharyngeal ulcerationAlveolar bone osteoporosis may be presentCriteria for referralControlled hyperthyroidism: depending on the comorbidities, dental care can be provided in the local dental clinic settingUncontrolled hyperthyroidism: delay elective dental treatment until the hyperthyroidism has been controlled; if urgent procedures are required, a hospital setting is preferableAccess/positionIf goitre is present, there may be pressure on the airway; consider a semi‐reclined position if this is the caseIf there is a bleeding/infection risk, arrange appointments earlier in the day and weekCommunicationLiaise with endocrinologist/physician if considering urgent dental treatment in a patient with untreated/significant hyperthyroidismSpeech may be affected if there is goitre or if there is any damage to the laryngeal nerves following surgeryConsent/capacityConsider the impact of heightened anxiety on decision making and consentPatients should be warned of the potential local (e.g. bleeding) and systemic complications (thyroid storm)Anaesthesia/sedationLocal anaesthesiaThe risks of giving epinephrine‐containing local anaesthetics in moderate amounts are more theoretical than realIf there is concern, prilocaine with felypressin can be given, but is not known to be saferSedationSedation may be considered since anxiety may precipitate a thyroid crisisNitrous oxide, which is rapidly controllable, is probably safest for dental sedationBenzodiazepines may potentiate antithyroid drugs and are thus contraindicatedAntihistamines such as hydroxyzine may also be usefulGeneral anaesthesiaThe hyperthyroid patient is especially at risk from general anaesthesia because of the risk of precipitating dangerous arrhythmiasAfter hyperthyroidism treatment, the patient is at risk from hypothyroidism; this must be borne in mind if a general anaesthesia is requiredDental treatmentBeforeBehavioural control and techniques to control anxiety are essential in patients with untreated hyperthyroidism requiring urgent dental treatmentDefinitive dental treatment should be delayed until the patient has been rendered euthyroidInvasive/surgical treatment will require specialised medical adviceDuringThe use of topical anaesthesia prior to the local anaesthesia may help pain control and anxietyLocal anaesthesia should be delivered using an aspirating syringe and should include a reduced amount of vasoconstrictor/epinephrineAfterGive patient written postoperative instruction and emergency contact detailsDrug prescriptionBenzodiazepines should be avoidedPovidone‐iodine and similar compounds are best avoided (iodine is taken up by the thyroid)Education/preventionReinforce meticulous oral hygiene and regular dental visits to prevent caries, periodontal disease and need for future extractions
Section II: Background Information and Guidelines
Definition
Hyperthyroidism is characterised by an increase in serum concentrations of the thyroid hormones, thyroxine (T4) and tri‐iodothyronine (T3). The secretion of T3 and T4, which occurs in thyroid gland follicles, is normally controlled by thyroid‐stimulating hormone (TSH), a protein secreted from the anterior pituitary gland, which in turn is regulated by thyrotropin‐releasing hormone (TRH), produced in the hypothalamus. When serum concentrations of thyroid hormones are elevated, TSH secretion is suppressed by a negative feedback mechanism.
Aetiopathogenesis
There are multiple causes of hyperthyroidism as summarised in Table 5.3.2
Graves disease is the most common causeAutoimmune disease that targets the thyroid gland with thyroid‐stimulating autoantibodies against TSH receptor antibodies (TRAbs and TMAbs)Predominantly occurs in women (8:1 ratio)Age of presentation 20–40 years old
General risk factors for hyperthyroidismMore common in womenOver the age of 60 years oldPositive family historyConsumption of excess iodine, either from foods or supplements, or from medications containing iodine (such as amiodarone)Pregnancy within the last 6 monthsOther health problems including pernicious anaemia, type 1 diabetes, primary adrenal insufficiency, myasthenia gravis
Clinical Presentation
Thyroid hyperactivity mimics epinephrine excessRaised pulse and anxietyHypertension with tachycardiaEyelid lag/retractionTremorDislike of heatIrritability
Cardiac disturbances are often present, particularly in older patients, and include tachycardia, arrhythmias (especially atrial fibrillation) and cardiac failure