What is the critical probing depth for non-surgical periodontal treatment?

From the Guidelines

The critical probing depth for non-surgical periodontal treatment is 5 mm, as established by Lindhe 1982, and supported by recent studies showing significant reduction in probing depth and clinical attachment level gain with non-surgical treatment for pockets up to this depth 1. This critical depth is based on the limited ability of periodontal instruments to effectively access and clean deeper pockets, as well as the difficulty in removing all bacterial deposits from these areas. The physical limitations of instrument access, visibility, and the complex root anatomy in deeper pockets contribute to this threshold. When treating patients with periodontal disease, clinicians should consider this 5 mm threshold when developing treatment plans and determining whether non-surgical therapy alone will be sufficient or if surgical approaches should be incorporated for optimal periodontal health outcomes. Some studies have shown that adjunctive antibiotic therapy can improve outcomes for non-surgical periodontal treatment, particularly for pockets with baseline probing depths ≥ 5 mm 1. However, the use of antibiotics should be considered on a case-by-case basis, taking into account the individual patient's needs and the potential benefits and risks of antibiotic therapy. Key points to consider when treating periodontal disease include:

• The effectiveness of non-surgical treatment decreases significantly for pockets deeper than 5 mm
• Adjunctive antibiotic therapy may improve outcomes for non-surgical periodontal treatment, particularly for deeper pockets
• The use of antibiotics should be considered on a case-by-case basis, taking into account the individual patient's needs and the potential benefits and risks of antibiotic therapy
• Recent studies have shown significant reduction in probing depth and clinical attachment level gain with non-surgical treatment for pockets up to 5 mm deep 1.

From the Research

Critical Probing Depth for Non-Surgical Periodontal Treatment

According to the study by Lindhe in 1982 2, the critical probing depth for non-surgical periodontal treatment is:

• 2.9 mm for scaling and root planing

Comparison with Other Studies

Other studies have also investigated the critical probing depth for non-surgical periodontal treatment, including:

• A study in 2021 3 which found that deep probing depths (≥ 5 mm) require time, exceptional skill, and perseverance for effective treatment
• A study in 2020 4 which found that baseline probing depth and interproximal sites predict treatment outcomes of non-surgical periodontal therapy
• A study in 2022 5 which found that scaling and root planning with periodontal endoscopy resulted in significant reductions in probing depth and plaque index compared to scaling and root planning alone in residual pockets with a probing depth ≥ 5 mm

Factors Affecting Treatment Outcomes

The studies suggest that several factors affect treatment outcomes, including:

• Probing depth: deeper pockets are associated with increased bleeding upon probing, elevated subgingival temperatures, and higher levels of pathogens 6
• Interproximal sites: distal sites show wider radiographic angles with shallow infrabony defects and pocket reduction is more obvious at distal sites than at mesial sites 4
• Oral hygiene: the level of oral hygiene maintained by patients during healing and maintenance is critical for resulting probing depths and attachment levels 2