Saliva protects teeth by washing away food and sugars, buffering acidic byproducts, supplying minerals for remineralization, and providing antimicrobial factors. When salivary flow is reduced, these protections diminish: acids from bacteria aren’t neutralized as effectively, plaque and sugars linger longer, and there’s less calcium and phosphate available to repair early enamel demineralization. The result is a more acidic, demineralized environment that raises the risk of dental caries. Other options don’t reflect this protective role of saliva: tooth whitening is a cosmetic change, enamel maturation happens during tooth development, and reduced saliva does not decrease caries risk.

Primary prevention means stopping disease before it starts. In dentistry, this means taking steps that keep teeth and gums healthy and protect teeth from injury. It targets multiple oral health issues, not just one. For caries, fluoride applications and sealants strengthen enamel and make decay less likely. For gingivitis, education on brushing, flossing, and effective plaque control helps keep gums healthy. For trauma, protective devices like mouthguards during sports reduce the risk of chipped or knocked-out teeth. Because primary prevention covers these preventive measures across different problems, the option that lists caries, gingivitis, and trauma together best captures its scope. The other choices imply protection of only a single condition, which misses the broader aim of preventing multiple common problems.

Tertiary prevention focuses on reducing disability and restoring function after disease has already caused damage, so it is applied later in the disease process. In dentistry this means interventions like restorations, rehabilitation, or prosthetic replacement that prevent further complications once damage has occurred. Primary prevention occurs before disease starts, and secondary prevention aims to detect and halt early progression. Therefore tertiary prevention is best described as happening later in the pathogenesis period.

In a child oral health examination, you’re looking for a range of findings that together show current status and future risk. Plaque tells you about hygiene and the potential for caries and gum issues; white spot lesions indicate early decay activity before cavities form; actual decay confirms areas that already need intervention. Enamel defects reveal developmental problems with enamel quality, which can influence susceptibility to decay and may affect how you manage treatment. Crowding or malalignment shows how teeth erupt and fit together, which can impact cleaning, eruption timing, and whether preventive or orthodontic steps are needed. Looking at all of these together gives a complete picture of oral health, so including plaque, white spots or decay, enamel defects, and crowding is the most comprehensive assessment for a child.