Periodontitis is Not Diagnosed by Probing Depths Alone

Probing depths alone aren’t a reliable indicator of periodontal support, and it is important to be thorough and precise in order to get the best treatment for the patient.

There are several things that make my blood boil when reading social media posts by dental hygienists. A big one is hearing a hygienist refer to calculus as “build up.” Where did that term come from? It’s a form of dental hygiene slang, I guess, often used among dental practitioners and with patients. Whoever created it needs to be whipped with a piece of dental floss or water tortured with an oral irrigator.

When I read in a blog about a dental hygienist who is questioning probing depths as the sole criterion for diagnosing periodontitis my hair stands on end and I start my deep breathing exercises to calm myself down. Periodontal probing is only 1 component of a comprehensive periodontal exam and cannot stand alone in diagnosing periodontitis.

Periodontitis is defined as a chronic, multifactorial, inflammatory disease associated with dysbiotic plaque biofilms and progressive destruction of the tooth-supporting structures. Primary features include loss of periodontal tissues as measured by clinical attachment loss (CAL) and alveolar bone loss in the presence of periodontal pocketing and gingival bleeding.1

Dental practitioners are often in a hurry when performing a periodontal exam and are sometimes unaware that probing depths are not necessarily all that is needed to diagnose periodontitis and treatment plan nonsurgical periodontal therapy. The absence of bleeding on probing is a reliable indicator of periodontal health excepting smokers.2 Experienced clinicians understand that many patients can maintain 4-6mm probing depths around certain teeth and if there is no bleeding upon probing, the patient may report 3-4 month routine periodontal maintenance long term with no change in CAL or alveolar bone loss. Smoking, however, exerts a strong, chronic, and dose-dependent suppressive effect on gingival bleeding and cannot be used as a reliable measure of inflammation in that population group.3

I recently read an online group post from a new dental hygiene graduate who didn’t seem to understand how to diagnose periodontitis and when to recommend nonsurgical periodontal therapy to a patient. Most of the time, in my experience coaching dental practices and teaching dental and dental hygiene students, both dentist and dental hygienist receive a competency-based education that includes a comprehensive periodontal exam. Rarely do I meet a dental hygienist who does not understand how to perform this exam. It’s easy to get turned around in dental practice, however, because clinicians are rushed for time and oftentimes, probing depths are the only measurements discussed during the exam.

In reviewing the literature on patient records and comprehensive periodontal assessment, I found a study conducted in one dental school where a total of 612 patient charts were generated and 157 met study inclusion criteria. Results revealed that 56.7% of the patient records did not include a periodontal diagnosis and another 10.8% did not follow current AAP Classification Guidelines. Most patients had a comprehensive periodontal exam performed (79.6%) but 20.4% had no comprehensive periodontal charting data recorded. Of the 157 records reviewed, 61.1% had no periodontal treatment specified.4

Why Probing Depths Alone Aren’t a Reliable Measurement

Probing depths alone aren’t a reliable indicator of periodontal support because measurements are made from the gingival margin (GM) which isn’t a stationary or stable tissue. The GM isn’t a stationary structure bound to bone and changes due to gingival recession, gingival overgrowth or swelling. Because it is not a fixed point, clinical attachment loss (CAL) is measured instead and is a more accurate indicator of periodontal support.

But how is CAL calculated? To calculate CAL, 2 measurements are needed: distance from the gingival margin to the CEJ and probing depth. In recession: probing depth (+) gingival margin to the CEJ (add). In tissue overgrowth: probing depth (-) gingival margin to the CEJ (subtract).

Comprehensive Periodontal Exam

The AAP makes it relatively easy for a dental practitioner to complete a comprehensive periodontal assessment by providing a checklist:

If you are unfamiliar with any of the items listed in the checklist, enlist the help of a local periodontist who will also guide you on criteria for referral to a periodontist. You can also refer to the items listed in your narrative when documenting coverage for SRP with a dental insurance company.

In my many years of performing periodontal assessments and providing narratives for

dental insurance companies, I cannot recall having any nonsurgical periodontal treatment (SRP) denied to a patient with a documented diagnosis of periodontitis. The more you stage and grade periodontitis using the 2017 new world workshop criteria, the easier it will get for you to write narratives to dental insurance companies.

Over the years, I have worked alongside and written about many great dentists and dental hygienists who are a tremendous inspiration to me. Collectively, they strive for clinical excellence and are constantly learning. In performing periodontal assessment, they are sticklers for details and their outcomes are excellent. To those dental practitioners who forsake detail and comprehensiveness and who are more concerned about profit over patient, I say “try a new approach”. There is another way to practice that will make you proud and leave a great legacy.


  1. Papapanou PN, Sanz M, Buduneli N, et al. Periodontitis: Consensus report of workgroup 2 of the 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions. J Periodontol. 2018;89 Suppl 1:S173-S182. doi:10.1002/JPER.17-0721
  2. Lang NP, Adler R, Joss A, Nyman S. Absence of bleeding on probing. An indicator of periodontal stability. J Clin Periodontol. 1990;17(10):714-721. doi:10.1111/j.1600-051x.1990.tb01059.x
  3. Holde GE, Jönsson B, Oscarson N, Müller HP. To what extent does smoking affect gingival bleeding response to supragingival plaque? Site-specific analyses in a population-based study. J Periodontal Res. 2020;55(2):277-286. doi:10.1111/jre.12713
  4. DeStaffany AM, Gurenlian JAR, Bono LK. Investigating periodontal diagnosis and treatment at one dental school [published online ahead of print, 2022 Jul 22]. Eur J Dent Educ. 2022;10.1111/eje.12838. doi:10.1111/eje.12838