Table 3.

Merin's periodontal post-treatment classification system [36].

Merin post-treatment classification	Characteristics	Recall Interval
First year	•Routine therapy and uneventful healing. •Advanced case with complicated prosthesis, furcation involvement, poor crown-to-root ratio or poor patient compliance.	3 months 1–2 months
Class A	•Excellent results well maintained for 1 year or more. •Good oral hygiene with minimal calculus. •No occlusal problems or complicated prostheses. •No remaining pockets, and no teeth with <50% of alveolar bone remaining.	6 months - 1 year
Class B	•Generally good results maintained reasonably well for 1 year or more, but some negative factors are present.	3–4 months
Class C	•Generally poor results post periodontal therapy and/or several negative factors.	1–3 months