Periodontitis Severity in Patients With Diabetic Retinopathy

A macular thickness map (ETDRS = Early Treatment Diabetic Retinopathy Study) is examined using OCT, with the center at the fovea centralis. According to the ETDRS map, the central 1 mm represents the fovea, the surrounding 3 mm area represents the inner retinal layers, and the outermost 6 mm area represents the outer retinal layers.

OCTA is a non-invasive technique that allows the evaluation of microvascular changes at the capillary level and imaging of the retinal plexuses layer by layer.

Definition: Retinal thickness is the distance between the internal limiting membrane (ILM) and the retinal pigment epithelium (RPE), measured by optical coherence tomography (OCT).

ETDRS Mapping: The macular region is divided into nine sectors based on the ETDRS grid:

Central subfield: A 1 mm diameter circle centered on the fovea. Inner ring (parafoveal region): 1-3 mm diameter, divided into superior, inferior, nasal, and temporal quadrants.

Outer ring (perifoveal region): 3-6 mm diameter, also divided into four quadrants.

Definition: The choroid is the vascular layer beneath the RPE. Choroidal thickness is the perpendicular distance from Bruch's membrane to the choroid-sclera interface (CSI).

Measurement: Typically obtained with enhanced depth imaging OCT (EDI-OCT), mapped according to the ETDRS grid.

Definition: The GCL is composed of the cell bodies of retinal ganglion cells, located between the inner plexiform layer and the retinal nerve fiber layer.

Measurement: OCT can quantify GCL alone or GCL + inner plexiform layer (GCL+IPL), usually reported using the ETDRS 9-sector mapping.

Definition: The RNFL consists of the unmyelinated axons of ganglion cells, located at the innermost surface of the retina.

Measurement: Often assessed in the peripapillary region or in the macular area using ETDRS mapping.

Definition: The CSI is the outer anatomical boundary of the choroid where it transitions into the sclera.

Role in Thickness Measurement: Serves as the lower reference point for choroidal thickness measurements (Bruch's membrane to CSI), which can be mapped according to the ETDRS grid.

Definition: The inner portion of the retina, located closer to the vitreous side.

Typically associated with the superficial capillary plexus. These layers are among the first affected in diseases such as glaucoma, optic neuropathies, and ischemic retinopathies.

Definition: The middle and outer portions of the retina, located closer to the photoreceptors.

Associated with the deep capillary plexus. Clinical relevance: Important changes are observed here in conditions such as macular edema, diabetic retinopathy, and age-related macular degeneration.

Definition: A circular area at the center of the fovea devoid of retinal capillary vessels.

Location: In the central fovea, approximately 500-600 micrometers in diameter.

Characteristics:

Contains the highest density of photoreceptors (especially cones). Avascular nature means nutrition is supplied via diffusion from the choroid. Responsible for the highest visual acuity. Clinical relevance: FAZ size, measurable by OCT angiography (OCTA), is an important biomarker in diabetic retinopathy, retinal vein occlusion, and macular ischemia.

Plaque Index (PI) (Silness and Löe, 1964) This index is used to evaluate the amount of dental plaque accumulation on tooth surfaces. Each tooth's four surfaces (buccal, lingual, mesial, distal) are examined using a probe or visually. Each surface is scored from 0 to 3. The average score is calculated for each tooth. The overall plaque index is obtained by averaging the scores from all examined teeth.

Score Description 0 No plaque.

• No visible plaque, but a slight film of plaque is detected when a probe is run along the gingival margin.
• Visible plaque along the gingival margin, forming a continuous band.
• Abundant plaque covering the gingival area and extending toward the middle of the tooth surface, including the interproximal spaces.

The Gingival Index is used to assess the presence and severity of gingival inflammation (gingivitis). Four surfaces of each tooth (buccal, lingual, mesial, distal) are examined visually and with a periodontal probe. The evaluation considers color changes, edema (swelling), tissue consistency, and bleeding on probing. Each surface is scored from 0 to 3. The average score per tooth is calculated, and then the overall average is used to determine the individual's GI score.

Score Description 0 Healthy gingiva: normal color and texture, no bleeding

• Mild inflammation: slight color change and swelling, no bleeding on probing
• Moderate inflammation: redness, edema, soft tissue, bleeding on probing
• Severe inflammation: marked redness and swelling, ulceration, possible spontaneous bleeding

This index is used to assess the presence and severity of gingival inflammation by observing bleeding after gentle pressure is applied to the gingival sulcus using a periodontal probe. A thin periodontal probe is gently inserted into the gingival sulcus with light pressure (approximately 20-25 grams). Bleeding occurring within 10-30 seconds is observed. Each measurement site is recorded as either "bleeding present" or "bleeding absent." Presence of bleeding is an early and sensitive indicator of gingival inflammation.

Score Description: 0 No bleeding 1 Bleeding present (mild or severe)

Using a Williams periodontal probe, the distance between the gingival margin and the base of the periodontal pocket is measured in millimeters at six sites per tooth: mesiobuccal, midbuccal, distobuccal, mesiolingual, midlingual, and distolingual. All teeth are measured. The values obtained from each site are summed and then divided by the total number of sites measured. This gives the average probing depth for the individual.

Measurement Interpretation 1-3 mm Healthy sulcus 4-5 mm Shallow to moderate pocket

≥6 mm Deep periodontal pocket (advanced disease)

Using a Williams periodontal probe, the distance between the enamel-cementum junction and the base of the periodontal pocket is measured in millimeters at six sites per tooth: mesiobuccal, midbuccal, distobuccal, mesiolingual, midlingual, and distolingual. All teeth are measured. The values obtained from each site are summed and then divided by the total number of sites measured. This gives the average probing depth for the individual.

CAL Value Interpretation 0-1 mm Healthy / minimal loss 2-3 mm Mild attachment loss 4-5 mm Moderate attachment loss

≥6 mm Severe attachment loss