Which electrolyte is NOT commonly found in saliva?

Calcium is not commonly found in saliva, which is primarily due to the fact that saliva's primary functions concern the oral cavity and digestion, not the regulation of calcium levels in the body. The main electrolytes found in saliva include sodium, potassium, and phosphate. Sodium and potassium play roles in maintaining osmotic balance and electrical neutrality, while phosphate is involved in buffering the pH of saliva and aiding in the remineralization of teeth.

In contrast, calcium, while it is important for various physiological functions, such as muscle contraction and neuronal function, is present in saliva at very low concentrations compared to the other electrolytes listed. Its presence is more associated with saliva's capacity to promote enamel remineralization rather than being a predominant component. Thus, calcium is not commonly present in significant amounts in saliva like the other electrolytes mentioned.