Final answer:
The Debris Index is the simplest dental index used to evaluate oral debris.
Step-by-step explanation:
The simplest dental index that can be used to evaluate oral debris is the Debris Index. This index assesses the presence or absence of plaque and debris on the teeth surfaces. The index is measured using a scoring system that evaluates different tooth surfaces for the amount of debris present, ranging from 0 (no debris) to 3 (abundant debris).