Zinc is a mineral needed in small amounts to maintain normal body function. A specific form of the mineral called zinc citrate is frequently added to mouthwashes and toothpastes to help prevent the formation of a harmful residue called plaque. Zinc appears to cause minor loss of tooth enamel; however, the degree of enamel loss associated with zinc use does not increase your risks for cavities, according to "International Dental Journal."

Enamel, Plaque and Cavities

Enamel is the hardest substance in the human body, according to Biology Online. It’s formed mostly from a type of calcium called calcium salt and covers the softer interior of teeth, called dentin. Plaque contains a combination of bacteria, saliva, food debris and acid. Within 20 minutes after you eat, plaque starts accumulating on your tooth enamel, and the acid content in plaque starts eating away the enamel surface. Eventually, this erosion can lead to tooth decay and the formation of holes in your enamel called dental caries, or cavities.

Zinc and Tooth Health

People who get adequate amounts of zinc naturally have some of this mineral in their teeth and saliva, as well as in plaque itself. According to a review published in 2011 in the “International Dental Journal,” zinc accumulations that develop in your teeth before they break through your gum line, or erupt, may play an important role in tooth maturation after eruption occurs. In toothpaste and mouthwash, zinc inhibits the growth of bacteria; in turn, this activity leads to reductions in plaque buildup and bad breath.

Zinc and Enamel Loss

Fluoride in dental preparations achieves some of its effects by hardening partially damaged enamel and dentin through a mineral replacement process called remineralization. Zinc can reduce the effectiveness of remineralization by lowering your enamel’s ability to absorb new mineral content, the authors of the “International Dental Journal” review report. In both laboratory studies and human trials, however, zinc’s effects on enamel do not trigger any increases in your overall chances of developing cavities.

Reduction of Harmful Effects

Factors that seem to reduce zinc’s harmful effects on tooth enamel include the irregular distribution of zinc in your enamel and calcium’s ability to push zinc in your enamel out of the way during remineralization, the authors of the “International Dental Journal” review note. In addition, new minerals deposited in areas of enamel that don’t contain zinc can grow over zinc-containing areas and increase their mineral content despite the presence of zinc. These factors, however, likely don’t quite offset zinc-related enamel damage, so zinc use can lead to some medically insignificant enamel loss. Consult your dentist for more information on zinc, zinc citrate and harmful changes in your tooth enamel.