A research team at Seoul National University Bundang Hospital (SNUBH) recently published a study demonstrating that the longer the interval between pausing osteoporosis medication and undergoing tooth extraction, the lower the risk of medication-related osteonecrosis of the jaw (MRONJ).

The study found that the relationship between the length of this drug holiday and the incidence of MRONJ varied significantly depending on the type of medication used, highlighting the importance of strategic discontinuation of osteoporosis treatments prior to surgical dental procedures.

The research team included Professors Kong Sung-hye from the Department of Endocrinology and Metabolism and Lee Hyo-jung from the Department of Dentistry at SNUBH. The study was jointly conducted with Professors Park Jung-hyun and Kim Jin-woo (co-corresponding author) from Ewha Womans University School of Dentistry and was published in the international journal Nature Communications (SCI(E), IF=16.1).

Normally, bone health is maintained through a balance between “bone resorption”--the removal of old or damaged bone tissue--and “bone formation,” the generation of new bone. In osteoporosis, this balance is disrupted, leading to bones becoming thinner and weaker as resorption outpaces formation.

Osteoporosis is commonly treated by inhibiting bone resorption to maintain or improve bone density. Injectable bisphosphonates are widely used, including zoledronate (administered once a year for high-risk patients) and ibandronate (administered quarterly for low-risk patients).

However, excessive inhibition of bone resorption can prevent the removal of aging bone tissue, causing damage to accumulate and potentially leading to serious side effects such as jawbone necrosis and atypical femoral fractures. The jawbone, in particular, is highly active due to constant stimulation from daily activities. When surgical procedures like tooth extraction or dental implantation are performed while bone resorption is suppressed, recovery can be delayed, increasing the risk of necrosis.

Despite this risk, there has been limited evidence on the optimal timing for discontinuing bisphosphonate therapy prior to dental surgery, resulting in a lack of clear clinical guidelines.

To address this gap, the researchers analyzed data from a national insurance database, focusing on patients with osteoporosis who had been treated with injectable bisphosphonates. A total of 152,299 patients were included in the study and categorized into four groups based on the duration of drug discontinuation prior to tooth extraction.

The results showed a clear trend: the longer the bisphosphonates were discontinued before tooth extraction, the lower the risk of developing MRONJ. Specifically, the incidence of jawbone necrosis was 1.28 percent in patients who had been off the medication for 90 days or less. This dropped to 0.71 percent in those who had discontinued for 91–180 days and further to 0.42 percent in those who had paused treatment for 365 days or more.

The study also found notable differences in MRONJ incidence depending on the type of bisphosphonate and the length of the drug holiday. For patients treated with ibandronate, a significant reduction in risk was observed after approximately 91 days of discontinuation. In contrast, for those on zoledronate, a meaningful risk reduction required discontinuation of over one year. The researchers attributed this to zoledronate’s longer half-life, which allows it to remain active in the body for an extended period.

According to the hospital, these findings provide an important foundation for establishing safer treatment strategies that balance osteoporosis management with dental procedures. The results are expected to inform both clinical practice and the development of academic guidelines.

“The results showed that discontinuing bisphosphonates may lower the risk of jawbone necrosis. However, we also observed a trend indicating that longer discontinuation periods were associated with an increased risk of vertebral and hip fractures,” said Professor Kong at SNUBH. “Patients with osteoporosis who are planning to undergo dental surgery should consult their healthcare providers to carefully evaluate the risks and determine the appropriate timing for discontinuing medication.”

“Osteonecrosis of the jaw is a challenging complication to treat and can significantly affect the quality of life, particularly in patients with osteoporosis,” said Professor Lee at SNUBH. “By adjusting the timing of treatment based on a patient’s medication history, we may be able to reduce the risk of this serious side effect.”