Final answer:
The absence of bleeding on probing is the most predictable indicator of periodontal stability, as it directly reflects a reduction in inflammation and a more stable periodontal condition.
Step-by-step explanation:
The most predictable indicator of periodontal stability is the absence of bleeding on probing. This is because bleeding on probing is a direct indication of inflammation, which is one of the hallmarks of both gingivitis and periodontitis. When there is no bleeding, it suggests that the inflammatory response has been mitigated, reflecting a more stable periodontal condition. In contrast, even with good patient compliance with maintenance visits, there could still be underlying issues that haven't been addressed, thus making it less predictable than the other indicators. Plaque index and gingival inflammation are also indicators of periodontal health but are more variable and dependent on patient behavior and daily dental care practices. Therefore, the absence of bleeding on probing stands out as the most reliable measure of periodontal stability.