And you thought you needed to be referred to another site....
It's all about hygiene, and keeping the tissues moist for comfort. Saliva has natural protective enzymes in it that help prevent perio disease and tooth decay. Without it meticulous cleaning every day, are a must, and the use of products that can help replace the enzyme balance like those from Biotene are what it takes to keep your teeth and mouth healthy.
Since he is so recently out of treatment, keep good habits of inspecting the interior of the mouth on a regular basis, this will catch opportunistic fungal infections like Candida early, and of course we are all carefully looking for any tissue changes that might need to be brought to the attention of our oncology team... early detection saves lives.