# What is the appropriate antibiotic administration to prevent MRONJ development after tooth extraction?

## TL;DR

This study found that a single pre-surgery dose of amoxicillin may be enough to prevent jaw bone issues after tooth extraction in patients on low-dose bone drugs.

## Contribution

The study provides evidence that shortening antibiotic use does not increase MRONJ risk in patients on bisphosphonates.

## Key findings

- MRONJ rates were similar with 2-day and single-dose amoxicillin regimens.
- MRONJ cases were mild and resolved within 12–16 weeks.
- Teeth with radiopaque root changes had significantly higher MRONJ risk.

## Abstract

There are no established guidelines for antibiotic administration to prevent the development of medication related-osteonecrosis of the jaw (MRONJ) after tooth extraction in patients receiving antiresorptive agents (ARAs). Since 2022, the duration of antibiotic administration during extractions in such patients has been intentionally shortened to prevent antimicrobial resistance at our hospitals.

This retrospective study involved 160 patients on low-dose bisphosphonates (BPs) requiring tooth extractions between 2019 and 2024 at four Japanese institutions. In 2019–2021, patients received amoxicillin (AMPC) 500 mg 1 h before and 750 mg per day for 2 days post-extraction. In 2022–2024, a single 500 mg dose of AMPC was administered 1 h pre-extraction. Patients were managed with tension-free wound suturing and regular follow-up. The rates of MRONJ development were compared between the two periods.

MRONJ developed in 3 out of 170 teeth (1.76%) in 2019–2021, and in 2 out of 147 teeth (1.36%) in 2022–2024, with no significant difference (P = 1.000). All MRONJ cases were low-stage (Stage 1) and healed completely within 12–16 weeks. Four out of five MRONJ cases (80%) exhibited radiopaque changes around the root. When all teeth in both groups were surveyed, MRONJ development was significantly higher in teeth with such changes compared to those without (4/58 vs. 1/259; P = 0.004).

A single preoperative dose of AMPC may be sufficient for tooth extractions in patients on low-dose BPs. However, teeth with radiopaque changes around the root require careful monitoring postextraction.