Tooth Enamel Remineralization

Tooth enamel is made of calcium hydroxyapatite, which is a crystalline calcium phosphate.

Our saliva contains calcium and phosphate. Our saliva can remineralize the tooth enamel. Acidic food can erode the tooth enamel. After a tooth grows up from the gum, it is eroded and remineralized every day. In an ideal situation, these two forces battle to a draw, and the tooth enamel stays more or less the same. If the rate of erosion is faster than the rate of remineralization, the tooth enamel gets thinner and thinner. When it is all gone, saliva can no longer build enamel on bare dentin, and cavities develop.

There are several materials that help remineralize tooth enamel.

Fluoride. It can bring calcium and phosphate to the tooth.

Toothpastes containing fluoride: many, such as Colgate Total.

ACP

ACP is Amorphous calcium phosphate. It remineralizes tooth structure.

Toothpastes containing ACP:

ARM & HAMMER: Complete Care Plus Enamel Strengthening.

CCP–ACP

Casein phosphopeptide, CPP, is a milk protein. When added to ACP, it has stabilizing qualities. This combined product, casein phosphopeptide and amorphous calcium phosphate (CCP–ACP) is known as Recaldent, invented at the University of Melbourne, Australia. The combination of CPP and ACP gives the product a longer exposure time (substantivity) on the teeth compared to ACP alone. 

Toothpastes containing CCP–ACP:

GC America: MI Paste

Trident Xtra Care gum

MI Paste Plus includes the addition of fluoride. The addition of fluoride to Recaldent has shown improved remineralizing properties over CCP–ACP alone.

NovaMin

It is calcium sodium phosphosilicate.

Toothpastes containing NovaMin:

Sensodyne Repair & Protect toothpaste (in Europe) ($6.10)

A similar product (sans "Novamin") called Biorepair is sold in the form of both toothpaste ($11.79) and mouthwash ($18.99), with the latter also having a pronounced antiseptic effect. (Germany)

Another brand is ApaCare Remineralising Toothpaste, ApaCare & Repair Tooth Repair Gel (mineralisation after brushing) and ApaCare Liquid Fluid Enamel. Like Biorepair, it is based on hydroxyapatite microparticles (hydroxyapatite is the primary mineral found in tooth enamel). (Germany)

Calcium Silicate and Sodium Phosphate
Regenerate Enamel Science Advanced Toothpaste

It is made by Unilever.

It re-builds a new layer of white enamel on the teeth

(UK) (£10.00)

Optimal Sun Exposure

When UVB shines on us, our skin produces vitamin D. Vitamin D is important in preventing heart disease and cancer, and gives us strong bones.

On the other hand, too much UVR may cause skin cancer.

So, how much sun exposure is optimal?

When UVB shines on us for 15 minutes, our skin can produce enough vitamin D that our health needs. So, 15 minutes sun exposure per day is optimal. It strikes a good balance between producing enough vitamin D and avoiding skin cancer.

For those 15 minutes, I think it is better to let the sun shine on our body (arms, legs, torso), instead of on our face. Sun damage is cumulative. Our face gets sun exposure all year round. So, over our lifespan, our face gets more sun exposure cumulatively than any other part of our body.

And for those 15 minutes, sunscreen should not be applied on the body, because the sunscreen will block UVB and interfere with our vitamin D production. 

Sunscreen

There are two types of active ingredients: chemical and physical.

Chemical ingredients absorb ultraviolet radiation (UVR). Physical ingredients block UVR.

Sunscreens based on chemical ingredients may cause skin reactions. Some chemical ingredients, such as oxybenzone, may get into the bloodstream.  Sunscreens based on physical ingredients do not typically cause skin reactions. I prefer physical ingredients over chemical ingredients.

UVR is divided into UVA1, UVA2, and UVB. UVB affects the top layer of the skin. UVA affects the top layer and deep layer of the skin. It is better to choose a sunscreen that block both UVA and UVB. The SPF factor only indicates how well it blocks UVB.  

There are two types of physical ingredients: Titanium Dioxide and Zinc Oxide. This table shows if they block different UVR's and if they clog pores.

Physical Filters	blocks	clogs pores
Titanium Dioxide	UVB, UVA2	yes
Zinc Oxide	UVB,UVA2, UVA1	no

I prefer zinc oxide over titanium dioxide.

Physical blockers can be further divided into non-nano particles and nanoparticles. Nano is < 100 nm. Nanoparticles can go too deep under the skin and get into the bloodstream. I prefer non-nano particles.

I prefer sunscreens that do not contain retinyl palmitate. It may cause skin tumors on sun-exposed skin.

Here are some sunscreens recommended by Environmental Working Group:

Butterbean Sunscreen Original, SPF 20.  $18.00 / 7 OZ ($2.57 / OZ)

Non-nano Uncoated Zinc Oxide 20%

Bare Belly Organics Sunscreen Cramm, SPF 30. $15.95 / 4 OZ ($3.99 / OZ)

25% Non-Nanoparticle Zinc Oxide

Badger Sport Sunscreen Cream, SPF 35. $15.28 / 2.9 oz ($5.27 / OZ)

Non-Nano Uncoated Zinc Oxide 22.5%