Aim: The aim of this study was to evaluate the relationship between initial probing depth (IPD) and changes in clinical parameters following non-surgical periodontal treatment (NPT) in chronic periodontitis patients.

Material and Methods: A total of 1672 periodontal pockets having 3 mm≤IPD≤9 mm in 15 chronic periodontitis patients were included. NPT consisting of oral hygiene instructions, scaling and root planing was applied in two sessions. Probing depth (PD), clinical attachment level, gingival recession (GR) were measured before and eight weeks after treatment. Pocket sites were grouped according to their IPD and root number of teeth as single- or multi-rooted.

Inclusion Criteria:

• Systemically healthy,
• Non-smoker,
• Chronic periodontitis diagnosed according to Armitage 1,
• Aged between 35 and 65,
• Not received any periodontal treatment within the last 3 months, • Have horizontal bone loss radiographically,
• Presence at least 20 natural teeth except third molars
• Consent to participate in the study.

Exclusion Criteria:

• Any systemic disease that might interfere with the prognosis of periodontal disease (i.e. diabetes mellitus, HIV infection),
• Smoking,
• Antibiotics, anti-inflammatory drugs or any other medication taken within the previous 6 months that may affect the outcome of the study,
• Any physical limitations or restrictions that might preclude normal oral hygiene procedures.