Why a dental exam comes before certain bone medicines

Being sent to a dentist as part of starting a cancer medicine surprises most people. Teeth feel unrelated to why you are in an oncology clinic in the first place.

They are related, though, and the reason is written into the drug's own labelling. FDA prescribing information for Xgeva instructs: "Perform an oral examination and appropriate preventive dentistry prior to the initiation of Xgeva and periodically during Xgeva therapy."

That is not small print you can skip. It is a direction to the prescriber, sitting right alongside the dosing instructions.

The condition being guarded against is osteonecrosis of the jaw. That means an area of jaw bone that does not heal the way it should.

Bone is living tissue. It constantly rebuilds itself. Medicines given to protect bone in cancer care work by slowing part of that rebuilding. That helps where cancer has weakened bone. But the jaw is a special case, since it gets exposed to injury from teeth and dental work all the time.

So the dental exam is not really about finding cavities for their own sake. It is about clearing out anything that might later need the kind of work the label says to avoid.

Get the dental problems dealt with before the medicine starts, not during.

The label is direct about what happens once treatment starts: "Avoid invasive dental procedures during treatment with Xgeva."

And if such a procedure cannot be avoided, it adds: "Consider temporary discontinuation of Xgeva therapy if an invasive dental procedure must be performed."

Read those two lines together, and the point of the pre-treatment appointment becomes clear. A tooth that needs pulling is a simple problem in the weeks before you start. That same tooth, six months into treatment, forces a hard choice about pausing a medicine you need.

Nobody wants to face that choice if a single appointment could have avoided it.

An oral examination and preventive dentistry means the usual things a dentist does. They look at your teeth and gums, take any images they need, and fix problems that are just starting.

Tell the dental practice why you are there. A dentist who knows you are about to start a bone-directed cancer medicine will approach the visit differently than one who thinks you have come in for a routine check. Bring the name of the medicine with you if you can.

The label also calls for this to happen at intervals during treatment, so expect to go back. Ask your oncology team how often they want it repeated. That interval is not the same for everyone, and it is easy for a follow-up to fall through the gap between two different care teams.

The patient counselling part of the label puts the job of noticing changes on you. Patients should tell their doctor or dentist if they get lasting pain or slow healing of the mouth or jaw after dental surgery.

Persistent is the key word. A sore mouth for a day or two after dental work is normal. Pain that keeps going, or a spot that does not close up as expected, is worth mentioning.

Tell both sides of your care team. Your dentist may not know what your oncologist has prescribed. Your oncologist may not know what your dentist has done. You are often the only one holding both halves of the picture. That is an unfair spot to be in, but a useful thing to know.

One appointment before you start. Repeat checks along the way. Invasive dental work put off where possible. Lasting mouth or jaw pain reported, not ignored. That is the whole of the precaution, and it is far less trouble than what it is meant to prevent.

• Call your oncology team and your dentist the same day if mouth or jaw pain has not settled after dental surgery, if a site in your mouth is not closing up as it should, or if you can see or feel exposed bone in your jaw. The Xgeva label tells patients to report lasting pain or slow healing of the mouth or jaw after dental surgery.
• Call your oncology team before you book anything if a dentist proposes an extraction or other invasive dental work while you are on treatment, because the label says to avoid those procedures during treatment where possible.