As we explained in Part 1, the health of your mouth depends on your mouth chemistry category (i.e. acidic, alkaline or neutral). Your mouth bacteria group, in turn, is determined by the type of food and amount of time you have food in your mouth. This is a concept known as "oral exposure time."

Healthy TeethTo care for your mouth, you need to become familiar with oral exposure time. The following examples provide insight into this important concept.

Example 1: Ignorant Isabel

Isabel hardly eats any sweets or carbohydrates but keeps getting cavities. She has given up on her teeth and just assumes she has "soft enamel." Ha!

Isabel's entire daily diet includes only 5% carbs in the form of mashed potatoes, rice and sugar-sweetened coffee. She eats her daily intake in three sittings (20 minutes each, a total of 60 minutes) and sips a cup of coffee in the morning and after lunch for about an hour for each cup.

Diagnosis: Isabel's oral exposure time to carbs is 66% due to her sugar-sweetened coffee sipping. As a result, she will get cavities.

Recommendation: Isabel needs to stop sipping her sugar-sweetened coffee or change to an artificial sweetener like aspartame (Nutrasweet) or sucralose (Splenda). She also needs to use high-fluoride toothpaste to fight the cavity chemistry of her mouth.

Example 2: Smarty Susan

Susan eats mostly carbs, but she does not get any cavities. She eats one large piece of chocolate cake every day in addition to the other food groups. But that chocolate represents 66% of her total calorie intake.

Susan eats all her daily intake in three sittings (20 minutes each, a total of 60 minutes), but she eats all the cake in only five minutes.

Diagnosis: Susan doesn't get any cavities because her oral exposure time to carbs is under 10%. She will have few if any cavities.

Recommendation: Susan could use a "total-control" toothpaste (e.g. Colgate Total) to protect against cavities and gum disease, or simply brush with a wet toothbrush, since she does not really need toothpaste at all.

Example 3: Confused Christine

Christine eats mostly protein and avoids sugars and starches altogether. She prides herself on never having a cavity before, so she thinks there's no need to go to the dentist much. However, she is not great about brushing and has a lot of plaque (the white stuff composed of disease-causing bacteria) around her teeth.

Christine recently went to her dentist, who said she has moderate gum disease along with three teeth that have severe gum disease and must be removed. Needless to say, she was shocked.

Diagnosis: Why does Christine need to have teeth removed? Her oral exposure time to protein is virtually 100%. The plaque bacteria that develop in a high-protein diet causes mouth chemistry to become alkaline. And an alkaline mouth with a lot of plaque causes gum disease.

Recommendation: Christine needs to keep her teeth clean of plaque bacteria and consider at least swishing with some sugar water for 60 seconds a day (even if she does not swallow the rinse because it would ruin her dietary goals). In addition, she should use a tartar-control toothpaste and Listerine antiseptic (the only over-the-counter mouthwash with mineral oil) to protect against progression of gum disease.

Example 4: Rocky Ricky

Ricky eats much like Christine — lots of protein, little sugars and starches. He also never has had a cavity and rarely goes to the dentist, but he does brush his teeth really well. Like Christine, he recently learned he has moderate gum disease along with three teeth that have severe gum disease and must be removed.

Why does Ricky have so much gum disease if he is great about brushing? Because his mouth saliva (spit) has lots of mineral in it. The mineral causes his plaque to harden into tartar (a "rocky" form of plaque), which his toothbrush can't remove. Because Ricky doesn't go to the dentist for regular cleanings, the tartar just sits there infecting his gums.

Diagnosis: Ricky needs to have teeth removed because a) his oral exposure time to protein is 100%, b) the plaque bacteria in a high-protein diet causes mouth chemistry to become alkaline, and c) an alkaline mouth with a lot of tartar causes gum disease.

Recommendation: Ricky should see his dentist regularly to remove the hardened plaque bacteria that cause gum disease. Additionally, he should use a tartar-control toothpaste and Listerine antiseptic to protect against progression of gum disease.

Example 5: Beefcake Bob

Bob eats much like Confused Christine and Rocky Ricky. He is muscle-bound and feeds those muscles a lot of protein. But he also brushes and flosses every day and sees his dentist every six months to keep tartar from collecting on his teeth. He also uses tartar-control toothpaste to keep his spit from mineralizing plaque on his teeth.

Diagnosis: Bob has a rather alkaline mouth, which predisposes him to gum disease and protects him against cavities. But since he doesn't let any plaque bacteria (or tartar) accumulate on his teeth, his dentist always gives him a clean bill of health. No cavities, no gum disease.

Recommendation: Bob should keep doing what he's doing!

Example 6: Average Joe

Joe likes protein and sweets but doesn't overdo it. He gets regular cleanings, flosses daily and brushes three times a day. He has had a few cavities and has mild gum disease on some teeth. Recently, his dentist put him on Colgate Total to give him fluoride (to fight cavities) and tartar-controlling compounds (to fight gum disease).

Diagnosis: Joe has a relatively neutral mouth and is unlikely to have any significant dental problems.

Recommendation: If Joe sticks to his dentist's plan, he'll be fine.

Example 7: Groovy Gary

Gary may confuse you because his dental problem is not related to his oral exposure. His teeth are strange in shape — very lumpy with deep grooves and pits. These grooves and pits trap particles inside the chewing surface of the tooth that a toothbrush cannot remove. As a result, Gary gets lots of cavities even though he does not eat much in the way of carbs and has a neutral mouth.

But the cavities that Gary gets are only in the deep grooves and pits of his teeth — not in between his teeth, where the surfaces are smooth and don't trap tiny food particles.

Diagnosis: Gary's problem has less to do with general oral exposure time and more to do with "micro-surface exposure time" — i.e. in the tiny areas where food gets trapped inside the tooth. This is not about overall mouth chemistry, but about the micro chemistry of isolated regions. These inaccessible areas trap food, produce an acidic environment and allow acid-producing bacteria to multiply. The acid, in turn, causes cavities.

Recommendation: Gary needs to get pit and fissure sealants on any teeth with deep pits and grooves that do not already have fillings in them. Also, in order to prevent cavities, his children (who have inherited his tooth shapes) need to get pit and fissure sealants as soon as their adult teeth begin to erupt.


We bet those examples made you think "Wow, I did not know that." Don't blame your dentist. Dentists don't have the time to teach you this! You owe it to yourself to keep reading!

Oral exposure time take-home points:

  • The time a food is in your mouth defines its impact on your teeth.
  • You can have sweets, but don't eat slowly if you are trying to avoid cavities.
  • Sticky foods will stay on your teeth and affect your oral exposure more than other foods.
  • Eating "healthy" may not be healthy for your mouth chemistry.
  • People that make a lot of tartar need to see their dentists at least every six months.