I don’t think a change in teeth could be seen in less than a week of keto especially if you were “already eating low carb”. I think this is the result of something that is more long term.
Tooth decay/demineralization?
Aqua_chonk
(Stickin' with mammoth)
#24
Well, actually, bacteria and/or nutritional deficiencies can cause enamel hypoplasia that presents as white spots. Inadequate oral hygiene is another culprit.
That Google thing you mentioned would be a good place to start. Good luck.
lfod14
#25
Tread lightly! Go too low for too long and you’re going to have a hell of a time fixing your metabolism.
White spots on teeth is usually from fluoride which IMO shouldn’t be used at all. This is the toothpaste I use, all natural stuff and it can remineralize as well. A lot of health stores carry it but if not you got Amazon.
JayGrxxn
#26
Woke up with dry mouth again. Still cant fix even that. Maybe its plaque build up and dry mouth is causing it.
mossypockets
(Amy)
#27
I recently was disappointed to find out I have 2 new cavities. It’s been many years since I last had a cavity! I’ve been doing keto since Sept, in maintenance since November. I too went through a period where everything was dry, including my mouth. I described it as feeling like beef jerky. Dry skin, hair, mucous membranes, etc. I started eating more carbs in January, and I felt much better.
You are correct in your assumption that white spots show demineralization. It’s happened to both my daughter and I. I also know that our teeth get the minerals they need from our saliva, so it makes sense that your dry mouth is causing it.
I personally wonder if those of us who are already lean need to do more carb cycling. It certainly has helped me in many ways, and I’ve had no problem maintaining my weight.
atomicspacebunny
(Bunny)
#28
Those white spots (hypocalcification) on the teeth are calcium deposits. I have one too 
…lol
Try adding type 2 resistant starch from a raw green banana or raw sweet potato sticks and see if that helps (…will not hurt your keto diet) or eat fruit every now and then? Make raw French fry like sticks (leave the skin on) place them in the fridge in a glass of water and munch on one periodically. Your mucous production (sometimes related to salivary gland issues[3]) might be way too low from lack of O-glycans you usually get from sugar. I have found this works for me because I was having problems producing tears and mucous and also lack of saliva but that’s just me! 
References:
[1] Endogenous host glycans are presented to bacteria in the intestinal lumen as O-linked glycans attached to secreted or cell-associated mucin glycoproteins (the major component of mucus), or as N-linked glycans present in shed epithelial cells. …” …More
[2] “…Symbiotic microorganisms that reside in the human intestine are adept at foraging glycans and polysaccharides*, including those in dietary plants (starch, hemicellulose, pectin), animal-derived cartilage and tissue (glycosaminoglycans and N -linked glycans), and endogenous glycans from host mucus (O -linked glycans). …” …More
[3] Sjögren’s Syndrome: “… is a disease in which the body’s defense system (immune system) attacks healthy tissues causing dryness of the mouth, eyes and other membranes of the body that secrete mucous. It is often found along with rheumatic disorders such as rheumatoid arthritis, scleroderma and lupus. “…The disease damages the glands that supply saliva to the mouth and tears to the eyes. …”
[4] How are polysaccharides different from monosaccharides and disaccharides? “…Sucrose (table sugar) is the most common disaccharide, which is composed of the monomers glucose and fructose. A polysaccharide is a long chain of monosaccharides linked by glycosidic bonds; the chain may be branched or unbranched and can contain many types of monosaccharides. …” …More
[5] What are the different classification of carbohydrates? “…The classification of carbohydrates is most commonly based on chemical structure, with the three most commonly known groups being monosaccharides, disaccharides and polysaccharides. These are discussed further in 'Carbohydrates and sugar. …” …More
[6] Besides the benefits of low sugar diet i.e. keto, you can also REGENERATE tooth enamel and skip the dentist doing this (Trisodium Phosphate: About 85% of the body’s phosphorus is in bones and teeth. Phosphorous is also present in smaller amounts in cells and tissues throughout the body. Phosphorus is also needed to help balance and use other vitamins and minerals, including vitamin D, iodine, magnesium, and zinc. …More
[7] Activator X (Vitamin K) also influences the composition of saliva