Honestly.... I would be more worried about dry mouth effects on your teeth than vaporizing glycerine.
I have Sjogren's Syndrome. I didn't know it for a while -- yes, I had dry mouth and eyes, but when I'd went to the eyedoctor I got eyedrops, the dentist gave me dry mouth rinse, and neither of them knew I was seeing a rheumatologist for what he misdiagnosed as fibromyalgia. It wasn't until I had experienced such severe tooth decay from dry mouth that I was contemplating dentures that my dentist asked me if I'd ever seen a rheumatologist, and yes, this tooth decay was progressing despite brushing 3x daily with a Sonicare toothbrush and flossing twice daily.
See, saliva coats your teeth and protects them. It also dilutes plaque. When you don't have enough saliva, plaque builds up faster. It is more acidic. Essentially it eats your teeth despite what you try to do.
I did have to get dentures -- top plate and bottom partial, because I couldn't afford the 16 root canals and 20 total crowns (four just needed crowns). I'm on pills to make myself produce more saliva, and that is helping save my bottom front six teeth. Smoking analogs dries your mouth out too, but I've heard many report dry mouth here, so that would be my biggest concern.
BTW, I am not dissing on the Sonicare at all -- the oral surgeon remarked that I had healthier gums than most of the teenagers he saw for wisdom teeth extractions, and that he had to work really hard to get my teeth out. I had no gum disease at all and all of my teeth were firmly rooted.
Brush, floss, drink lots of water, don't drink sugared beverages, consider rinses with xylitol, and don't drink ANYTHING but water after you brush your teeth before bed. Keep a bottle of water beside the bed and drink it if you wake up dry. That will not only prevent dry-mouth associated caries, but the other causes of them as well.