Early stage cavities begin with a silent onset. In the initial stages, a cavity remains in the enamel layer, where nerve fibers do not reach, which allow escape from immediate detection by the nerves. 

Location plays a roll as well. Consider the cavities that form on the chewing surfaces of the molar teeth. These teeth tend to have thicker enamel insulating the tooth and reducing changes of sensitivity. This natural anatomical diversity we have in our dentition can mask the early signs of decay. 

Our pain threshold varies per individual. Some exhibit discomfort because they are actually sensitive while others just have a higher threshold, therefore leading to cavities going unnoticed for a longer period of time.

Cavities tend to have a slow progression as well. This allows for the tooth to adapt to the changed environment and can minimize sensitivity as a defense which allows concealment of early caries.

Regardless of the sensitivity levels, the best way to prevent progression of dental disease is maintaining regular dental checkups. Professional comprehensive exams and x-rays during these visits can uncover underlying issues that may not be apparent to the patient.

Prevention and early detection is paramount to maintain optimal oral health and preserving a beautiful smile.