Dental management of patients with bone and calcium disorders ( Including osteoporosis)

Osteoporosis is a common health problem. It is characterized by low bone mass and deterioration in the microarchitecture of bone ( bone quality) , leading to increased bone fragility and a consequent increase in fracture risk. About 50 % of women can expect to sustain fractures in their lifetime. Low trauma fractures can occur in 30 % of older men and one third of all hip fractures in the community occur in men. Drug therapy is aimed at improving bone strength further bone loss and/ or increasing bone mass.

Osteopenia refers to bone mass that is lower than normal, but not low enough to be classified as osteoporosis. Other bone and calcium disorders include Paget disease of bone, malignancy involving bone, and hypercalcaemia.

The bisphosphonates are one of the drug classes used to treat bone and calcium disorders; however, they have been related to osteonecrosis of the jaws.

Dental issues : Bisphosphonate related to osteoporosis of the jaws

Bisphosphonate related osteonecrosis of the jaws ( BRONJ) is an area of exposed bone in the jaws persisting for more than 8 weeks in a patient treated with bisphosphonate.
It is usually painful, and sometimes there is draining sinus with extensive undermining of the surrounding mucosa overlying the necrotic bone. The most common complication of BRONJ is soft tissue infection, which may be extensive. Other pathologies should be excluded, particularly malignancy at the site and a history of head and neck radiotherapy where the condition is correctly described as osteoradionecrosis of the jaws.

BRONJ is thought to be caused by bisphosphonate inhibition of osteoclastic bone resorption, leading to reduces bone turnover. The severity of BRONJ can be classified in stages, ranging from stage 0 with bone pain but no exposed to stage III with full thickness bone involvement, pathologic fracture, and extensive soft tissue infection and fistulae.

BRONJ most commonly follows tooth extractions, but may be associated with poorly fitting dentures. There have also been cases of BRONJ with out evident bone invasive procedures; these commonly occurred over exostoses, such as tori or mylohyoid ridges.

Initial reports based on pharmaceutical data described the incidence of BRONJ in patients treated with oral bisphosphonates as 1 in 10 000 to 1 in 100 000. Indipendent investigations in Australia and North America show an incidence in the order of 1 in 500 to 1 in 1500 patients. The incidence is much higher in patients treats with intravenous bisphosphonates, usually for malignancy, where BRONJ can occur in 1 in 10 to 1 in 15 patients following extractions.

Denosumab is a new monoclonal antibody for osteoporosis, similarly to the biphosphonates, acts by inhibiting bone resorption. Case of osteonecrosis of the jaws have been reported in patients taking denosumab, which supports the view that osteonecrosis of the jaws is caused by suppresion of normal bone turnover. The approach to dental management for patients treated with denosumab should be the same as for patients treated with bisphosphonates.

Dental procedures in patients treated with biphosphonates

Before commencing long term oral or intravenous bisphosphonates in any patient, the medical practitioner should refer the patient to a dentist to undertake a comprehensive oral examination, including pulp tests and radiographs, to ensure that they are dentally fit and unlikely to require extractions in the foreseeable future. The dentist should eliminate caries ( eg extractions, restorations), establish a healthy periodontium ( eg scaling, extractions), and advise the medical practitioner when the patient is dentally fit. Patients should be informed of the potential benefits and harms of bisphosphonate therapy, including the risk of devaloping BRONJ.

All patients should be refferred to a dentist before conmencing long term or intravenous bisphosphonate therapy

After commencement of a biphosphonate, the dentist shoul monitor the patient's oral health regular ( eg clinical dnetal examinations, radiographs) , undertake dental treatment as required and , if worn, ensure dentures fit well. Patients with dental implants need to have implants monitored as loss osseointegration and BRONJ may occur.

Do not undertake rxtractions or bone surgery in any patient until it is known if they are being treated with bisphosphonate and, if so, until their risk of BRONJ has been assessed. The risk of BRONJ is related to potency of the bisphosphonate ( nitrogen containing bisphosphonates are more potent than non nitrogen containing bisphosphonates), the total dose , and the duration of bisphosphonate therapy.The patient's underlying bone condition, age and comorbidities are also factors. Biphosphonates enter the bone matrix where they remain for at least 1 year, and possibly up to 10 years. Clinically , however, the risk of BRONJ decreases 1 year after therapy is ceased.

C- terminal telepeptide ( CTX) is a breakdown product of bone resorption and therefore its serum concentration provides an estimate of bone turnover. The normal serum CTX concentration is between 400 and 500 picograms/ mL. Measurement of the fasted morning serum CTX concentration may be considered to assess the risk of BRONJ .

IF the CTX concentration is 150 pg/mL or more , bone invasive procedures can safely proceed. If the CTX concentration is less than 150 pg/mL, patients are at risk of developing BRONJ and consideration should be given to a " drug holiday", where the bisphosphanate is ceased temporarily. Temporary ceassation of bisphosnate therapy should be decides by the patient's medical practitioner after consultation with dentist. The CTX concentration usually increases by 25 pg/mL each month after the bisphosphonate is ceased. This can be used to estimate when bone invasive procedures can be safely undertaken and the length of the drug holiday.
A repeat CTX test should be performed to confirm the concentration before undertaking any bone invasive procedures. Generally, bisphosphosnate therapy can be started 10 days after an extraction.

Bisphosphonate therapy should not be ceased without consulting the patients's medical practitioner.

All procedures involving bone ( eg implant placement, orthodontic tooth movement, periapical or radicular surgery, periodontal flap surgergy ) required careful consideration and informed consent from the patient before proceeding.

If an extraction is unavoidable , it should be performed with the minimum of trauma and with closure of socket by suturing. Medically well patients an usually be managed in general dental practice. Severely medically compromised patients on intravenous biphosphosnates for malignancy are best managed by dental specilist associated with the oncology team.If the patient is medically compromised ( particularly if they have diabetes or are taking corticosteroids) , consider antibiotic prophylaxis.

Monitor the extraction wound until it heals. Healing may be slow. If bone is still clinically visible at 8 weeks, BRONJ has occurred and urgent specialist referral is required. Do not curette nonhealing sockets.

History taking ralating to bisphosphonates

It is highly recommended that dentists check the following points with patients or in the patient's medical history:
1. Have you received treatment for any bone or calcium disorders?
Conditions that may be treated with a bisphosphonate include:
* Osteoporosis
* Paget disease of bone
* Cancer with spread to bone ( eg breast, prostate, liver, lung , kidney)
* Multiple myeloma

2. Are you taking any bisphosphoanate madications?

Bisphosphonates are usually taken orally, either daily or once weekly. However, they are sometimes administered intravenously and given less frequently ( eg once yearly).

Bisphosphonates available in Australia are:

* Nitrogen containing biphosphonates ( alendronate, risedronate, pamidronate, zoledronic acid, ibandronate)
* Non nitrogen containing bisphosphonates ( Clodronate, tiludronate).

If the answer to either of the questions is "yes", the patient is at risk of biphosphnate ralated osteonecrosis - do not proceed with extractions or bone surgery without careful establishment of the facts regarding the bone or calcium disorder and the medication history. Specialist advice may need.