What is the prognosis for a tooth with Grade III or IV furcation involvement and Miller class III mobility?

The prognosis for a tooth with Grade III or IV furcation involvement, combined with Miller class III mobility, is classified as hopeless. In this context, Grade III or IV furcation involvement indicates advanced periodontal disease where there is complete or nearly complete loss of bone support in the furcation area, making it difficult for the tooth to maintain stability and function.

Additionally, Miller class III mobility signifies significant tooth mobility due to a compromised periodontal attachment, further contributing to the tooth's instability. In cases of severe furcation involvement and high mobility, the periodontal support structure is inadequate for the tooth to be retained effectively.

Given these factors, the prognosis leans toward hopeless, as the tooth is highly likely to become non-restorable or lost due to the extensive periodontal and structural compromise. This understanding underscores the importance of assessing both furcation involvement and mobility when determining treatment options and overall prognosis in periodontal cases.