What classification of decay is located on the gingival third on the facial or lingual surfaces of teeth

Smooth-surface decay.

Explanation:

Dental caries is a multifactorial infectious disease of the hard tissues of the tooth (enamel and dentin) that arises on the surface of the tooth and can spread to the pulp. Smooth-surface decay are dental caries that originate on the smooth surfaces of the proximal general teeth, or in the gingival third of the facial and lingual surfaces. This cavity forms when plaque builds up and bacteria are not killed on the flat surface of the teeth.

after receiving a stimus, the sensory receptors send(s) signals to the appropriate area of the body.  

the must be sensory neurons.  

hope its .