What is the most common space involved with erosion of the lingual plate adjacent to tooth #20?

The most common space involved with erosion of the lingual plate adjacent to tooth #20, which is the second molar in the lower jaw, is the submandibular space or sublingual space. Erosion in this region typically occurs due to dental infections or conditions that lead to the spread of osteomyelitis or other forms of infection in the mandible, particularly from associated teeth.

When there is infection in the area of the tooth roots, such as from untreated dental caries or periodontal issues, the inflammatory process can lead to the breakdown of bone and soft tissue, which may allow the spread of infection into adjacent anatomical spaces. The submandibular space is particularly vulnerable because it lies directly beneath the mandible and is in close proximity to the roots of the molars.

Although other spaces like the mental space, buccal space, and pterygomandibular space are involved in maxillofacial infections, they are less commonly associated with erosion of the lingual plate adjacent to lower molars compared to the submandibular and sublingual spaces. The anatomical relationships and potential pathways for infection propagation make the submandibular space the most likely area to be impacted in this scenario.