Diagnostic Testing & Understanding Your Periodontal Chart

A diagnosis of periodontitis is never made with a quick visual “look-see.” Because the disease happens largely out of sight—beneath the gum line and inside the bone—your dental team must perform a series of precise, physical measurements ^[1]. Understanding these numbers will help you track your own progress and actively participate in your treatment plan.

The Periodontal Chart: A Detailed Map

During a comprehensive exam, your clinician creates a “map” of your mouth. They examine your teeth at six specific sites—three on the cheek side and three on the tongue side ^[2][3]. For each of these sites, they record several key data points:

• Probing Pocket Depth (PPD): This is the distance from the top of the gum margin to the bottom of the “pocket” where the gum attaches to the tooth ^[4].
  • Interpretation Context: A deeper pocket does not automatically equal active disease. A 4 mm pocket can be a healthy, stable site, or a “pseudopocket” caused by swelling. A treated 5 mm pocket may also be stable if it is not bleeding. Your clinician interprets these depths alongside your bleeding scores and treatment history ^[5].
• Gingival Recession: If your gums have pulled away, exposing the tooth root, this measurement is recorded separately ^[4].
• Clinical Attachment Level (CAL): This is the total amount of support lost. For example, if you have a 4 mm pocket plus 2 mm of recession, your total attachment loss is 6 mm ^[4]. CAL is an important measure of historical damage and helps determine your Stage of disease, though it is not the sole determinant ^[6].
• Bleeding on Probing (BOP): Healthy gums generally do not bleed when gently probed. If a site bleeds, it is a sign of inflammation in the pocket lining ^[7]. Your team may calculate a “Full-Mouth Bleeding Score” as a percentage of all sites that bleed ^[7].

Checking the “Foundation”

Beyond the numbers, your clinician will check for signs that the disease is affecting the tooth’s physical stability:

• Furcation Involvement: In teeth with multiple roots (like molars), bone loss can reach the “fork” where the roots branch out ^[8]. Your dentist uses a special curved tool called a Nabers probe to see if they can feel into this space. Depending on the class (severity), this can be a complexity factor that influences your Stage ^[6][9].
• Mobility: Teeth are gently wiggled to see if they move more than normal. Mobility is graded from I (slight) to III (severe/moveable with the tongue or lip) ^[10].

The Role of Radiographs (X-rays)

While probing measures the “soft” attachment, X-rays are the only way to see the “hard” bone level ^[1].

• Bitewing and Periapical X-rays: These provide the most detail for individual teeth, showing the specific pattern of bone loss. Keep in mind that X-rays are 2D images and may not show all bone loss on the front or back of the tooth ^[11].
• Horizontal vs. Vertical Loss: Horizontal bone loss looks like an even “lowering of the tide” across several teeth. Vertical (or angular) bone loss looks like a crater next to a single tooth ^[12].
• Bone Loss Percentage: Your dentist will estimate how much of your root is no longer surrounded by bone. Losing more than 33% (the upper third of the root) generally moves you into a more severe Stage, though this is interpreted alongside other factors ^[6][13].

The Exam Process

Many dental visits use a Periodontal Screening tool as an appropriate first step. If this screening indicates signs of disease, a comprehensive periodontal evaluation—including a 6-point probing chart and necessary X-rays—should follow to confirm the diagnosis and Stage ^[2][14].