Osteoporosis and Orthodontic Treatment

How osteoporosis affects bone structure

Osteoporosis is diagnosed when bone mineral density, measured by DEXA scan, produces a T-score of minus 2.5 or below. Osteopenia describes T-scores between minus 1.0 and minus 2.5. In both conditions, reduced trabecular bone density means the alveolar bone supporting the teeth is less dense than in a healthy adult. Orthodontic tooth movement relies on the cycle of bone resorption on the pressure side of a tooth and bone deposition on the tension side. In osteoporotic bone, this cycle is altered: the resorption phase tends to be more active relative to formation, which has implications for treatment planning.

Does bone density affect how teeth move?

The evidence suggests that teeth may move more readily in osteoporotic bone than in normal-density bone — the reduced bone resistance means less force is needed to initiate tooth movement. However, this comes with an important trade-off: the increased resorptive activity associated with osteoporosis raises the risk of external apical root resorption (EARR), where the root tip shortens during treatment. Root resorption is a recognised risk of all orthodontic treatment, but the risk may be elevated in patients with osteoporosis, particularly with prolonged treatment or heavy forces. Orthodontists managing patients with osteoporosis therefore typically use lighter forces, shorter treatment arcs, and monitor root lengths on radiographs more frequently than standard protocols.

The bisphosphonate overlap

Many patients with osteoporosis are prescribed bisphosphonates — medicines such as alendronate, risedronate, or zoledronic acid — to reduce bone resorption and fracture risk. Bisphosphonates accumulate in bone and inhibit osteoclast activity, which has a different effect on tooth movement: rather than accelerating movement, they tend to slow it and can make tooth movement less predictable. The duration of bisphosphonate use and the cumulative dose are important factors. Patients who have been taking oral bisphosphonates for many years carry a degree of residual drug in their bone long after stopping. Any patient on bisphosphonates should disclose this to their orthodontist, as it affects treatment planning, force levels, and the decision about whether tooth extractions as part of treatment carry a small risk of medication-related osteonecrosis of the jaw (MRONJ). The risk is low with oral bisphosphonates at osteoporosis doses, but the orthodontist should liaise with the prescribing GP or rheumatologist.

DEXA scan and its relevance

Patients who have had a DEXA scan should share their T-score results with their orthodontist. This helps the orthodontist understand the baseline bone quality. If you have not had a DEXA scan but have risk factors for osteoporosis — post-menopausal woman, family history, steroid use, low body weight — it is worth discussing referral for a scan with your GP before starting orthodontic treatment. Having a baseline measurement also allows comparison if concerns about bone changes arise during treatment.

Calcium and vitamin D during orthodontic treatment

Adequate calcium and vitamin D are essential for bone metabolism and tooth movement. Bone remodelling during orthodontic treatment requires both minerals in sufficient supply. Patients with osteoporosis are frequently prescribed calcium and vitamin D supplementation as part of their bone health management, and continuing these during orthodontic treatment is important. Vitamin D deficiency is common in the UK due to limited sunlight exposure. Patients who are not already supplementing should discuss this with their GP. There is evidence that vitamin D deficiency is associated with slower, less predictable tooth movement and potentially increased risk of root resorption.

Post-menopausal bone loss and timing of treatment

Bone loss accelerates significantly in the first five to ten years after menopause due to oestrogen withdrawal. Women considering orthodontic treatment during this period should be aware that their alveolar bone may be at its most vulnerable. This does not make orthodontic treatment impossible, but it does mean the orthodontist should be aware of bone health status and adapt the approach accordingly. Women who are several years post-menopause and whose bone density has stabilised — or who are on effective bone-protective therapy — are generally considered to carry lower additional risk.

Liaison with GP and rheumatologist

For patients with significant osteoporosis, a conversation between the orthodontist and the treating GP or rheumatologist is good clinical practice before starting treatment. The GP can confirm current medication, advise on planned medication changes, and provide DEXA scan results. If a patient is due to start bisphosphonate therapy, it is worth considering whether orthodontic treatment should begin before commencing bisphosphonates, as this avoids the additional complexity of managing tooth movement while bisphosphonates accumulate in bone.

Useful related pages

This guide is for general information only. It is not a diagnosis, treatment plan, or substitute for advice from a registered dentist or orthodontist.