Periodontal Indices and Clinical Evaluation Methods

General Classification and Characteristics of Clinical Indices

Clinical indices serve as the numerical expression of a specific clinical situation, allowing for the objective description and recording of the status of either a single patient or an entire community. Functionally, indices are categorized into two primary types: Simple Indices and Cumulative Indices. Simple Indices evaluate a dichotomy of presence or absence (recorded as YES/NO or +/-) regarding a condition, symptom, or the cause of a disease, such as the presence of bleeding or bacterial plaque. In contrast, Cumulative Indices evaluate the evidence of a condition by summing the past state of the disease with the current clinical moment, exemplified by the DMFT caries index.

Indices are also classified based on the evolution of pathology into three groups: Irreversible, Reversible, and Mixed. Irreversible indices measure permanent alterations and non-recoverable damage, such as gingival recession. Reversible indices measure symptoms that can regress partially or totally, following the clinical course of the disease closely, such as gingival inflammation or tooth mobility. Mixed indices evaluate both irreversible damage and reversible symptoms simultaneously, such as the Ramfjord Periodontal Disease Index (PDI).

An ideal clinical index must meet several rigorous requirements to be validated for clinical use. It must be simple, rapid to apply, valid, reliable, and easily reproducible by different operators without variations. Furthermore, it should be objective (free from personal interpretations), statistically processable, economical, and absolutely not uncomfortable for the patient.

Caries Indices: DMFT and Its Variants

The DMFT index (Decayed, Missing, Filled Teeth) is a universally recognized cumulative index established by Klein, Palmer, and Knutson in 1938. It quantifies the number of permanent teeth that are decayed, lost due to caries, or filled. The calculation is performed on a maximum of 28 teeth, resulting in values ranging from $0$ to $28$. Specifically excluded from this calculation are the third molars (eighths), supernumerary teeth, and teeth that are not fully erupted.

The individual components of DMFT have specific clinical meanings. The "D" (Decayed) component counts the elements or surfaces with active caries; it is important to note that simple demineralizations, such as white spots, are not considered. The "M" (Missing) component reflects the dental history, but a tooth is counted only if it was lost specifically due to carious pathology. Extractions for orthodontic reasons, trauma, or periodontal disease are categorically excluded. When using the surface variant (DMFT-S), a missing tooth is automatically assigned a value of $4$ or $5$ lost surfaces depending on the anatomy of the tooth. Finally, the "F" (Filled) component accounts for conservative or prosthetic therapies performed to treat past caries.

For clinical application, the individual DMFT is the simple sum of the three values (e.g., if $D = 2$, $M = 2$, and $F = 8$, the DMFT is $12$). For collective population assessments, the group average is calculated using the following formula:

$\text{Collective DMFT} = \frac{\text{Total DMFT of the population}}{\text{Total number of examined subjects}}$

Caries Indices for Specific Populations and Conditions

The dmft index (Grubbel, 1944) is the exact equivalent of the DMFT but is used for deciduous teeth and is written in lowercase. It evaluates 12 specific deciduous teeth, including 4 canines and 8 molars, resulting in a range from $0$ to $12$. In patients with mixed dentition, such as an 8-year-old child, clinicians must not mix the numbers; they must calculate the DMFT for permanent teeth and the dmft for deciduous teeth separately.

The Root Caries Index (RCI), established by Kats in 1984, specifically evaluates root caries. Only exposed root surfaces are considered at risk, with four surfaces calculated per tooth. The formula for the RCI is:

$\text{RCI} = \left[ \frac{\text{Decayed Roots} + \text{Filled Roots}}{\text{Decayed Roots} + \text{Filled Roots} + \text{Sound Roots}} \right] \times 100$

Other specific indices include the Significant Caries Index (SiC), which serves to isolate the most at-risk group within a population by ordering individuals by increasing DMFT and averaging the DMFT of the top third of that group. The FS-T (Filled Sound Teeth) is a "positive" index calculated by summing teeth that are filled and those that are sound, starting from the DMFT data.

Periodontal Diagnostics and Probing Techniques

Periodontal indices aim to evaluate the degree of inflammation, monitor tissue attachment loss, measure oral hygiene levels, and objectively establish treatment needs. A healthy periodontium is clinically defined by the absolute absence of inflammatory signs, including bleeding, redness, swelling, exudate, or tenderness. Probing is conducted using the "Walking Probe" technique, where the probe is inserted into the sulcus and small, rhythmic, step-like oscillating movements are made. A circumferential 360-degree probing must be performed around the dental element.

The correct insertion axis requires the probe to be kept strictly parallel to the long axis of the tooth. The only exception occurs in interproximal areas (mesial/distal) or in the presence of prosthetic work, where the probe is slightly tilted to insert below the contact point. The movement is a continuous "up and down" along the perimeter without ever fully extracting the tip of the probe from the sulcus.

In epidemiological studies, six specific "Ramfjord Teeth" are used to represent the entire dentition as a statistically valid sample. These teeth are: 1.6 (Upper right first molar), 2.1 (Upper left central incisor), 2.4 (Upper left first premolar), 3.6 (Lower left first molar), 4.1 (Lower right central incisor), and 4.4 (Lower right first premolar). If one of these teeth is missing, the adjacent tooth is evaluated instead.

Indices of Inflammation: BoP and GI

Bleeding on Probing (BoP), as described by Ainamo and Bay, indicates the state of active inflammation or health of periodontal tissues. It is mandatory for initial and final periodontal charts. Probing is performed on 4 surfaces per tooth, and the clinician must wait at least 10 seconds after insertion to record the presence (+) or absence (-) of bleeding, as it may be delayed. The formula is:

$\text{BoP} = \left( \frac{\text{Number of bleeding sites}}{\text{Total number of sites analyzed}} \right) \times 100$

The therapeutic goal is to reduce this index below the clinical threshold of $30\%$. For example, if 32 teeth are probed across 128 sites and 71 sites bleed, the calculation is $(71 / 128) \times 100 = 55\%$.

The Gingival Index (GI) of Löe and Silness is a reversible index that quantifies the severity and quantity of inflammation in the gingival tissues only. It evaluates 4 sites per tooth (vestibular, mesial, distal, and lingual/palatal) visually (color/consistency) and instrumentally (bleeding by running the probe along the sulcus wall). The four clinical grades are:

• Grade 0: Normal gingiva.
• Grade 1: Mild inflammation, slight edema, and color variation, but NO bleeding on probing.
• Grade 2: Moderate inflammation, redness, and edema, with BLEEDING on probing.
• Grade 3: Severe inflammation, marked redness and edema, ulcerations, and SPONTANEOUS bleeding.

The GI for a single tooth is the sum of the 4 area scores divided by $4$. The final group or individual average is interpreted as: 0 (Excellent, healthy tissue), 0.1 – 1.0 (Good, mild gingivitis), 1.1 – 2.0 (Sufficient, moderate gingivitis), and 2.1 – 3.0 (Insufficient, severe gingivitis).

Plaque Indices: PI, PFS, and PI-PRC

The Plaque Index (PI) by Löe and Silness (1964) measures the thickness of plaque on 4 surfaces using a mirror and explorer after drying with air. The grades are: 0 (Absence of plaque), 1 (Film observable only by running the probe or using disclosing solution), 2 (Moderate accumulation visible to the naked eye), and 3 (Abundance of soft deposits in the sulcus and on surfaces). Interpretation scales are 0.1-0.9 (Good control), 1.0-1.9 (Sufficient), and 2.0-3.0 (Insufficient).

The Plaque Free Score (PFS) by Grant, Stern, and Everett (1979) is a positive index using plaque disclosing solution to determine the percentage of surfaces free of plaque. The PI-PRC (Simplified Plaque Control Record) or O'Leary index records the dichotomous presence (+) or absence (-) of plaque on 4 sites of all teeth in the arch using disclosing solution. The formula is:

$\text{PI-PRC} = \left( \frac{\text{Total number of walls with plaque}}{4 \times \text{Number of teeth present}} \right) \times 100$

For example, if a patient has 31 teeth (124 total surfaces) and plaque is found in 57 sites, the calculation is $(57 / 124) \times 100 = 46\%$.

Periodontal Treatment Needs: CPITN and PSR

The Community Periodontal Index of Treatment Needs (CPITN), established by the WHO in 1997, divides the mouth into sextants. Only the worst condition in each sextant is recorded, and sextants with only one tooth are ignored. It evaluates bleeding, calculus (supra/subgingival), and pocket depth (4-5 mm or $≥ 6\,mm$). The index teeth for subjects over 20 years old include 10 teeth (1.7, 1.6, 1.1, 2.6, 2.7, 3.7, 3.6, 3.1, 4.6, 4.7), while subjects under 20 years old use 6 teeth (1.6, 1.2, 2.6, 3.6, 3.1, 4.6).

CPITN Codes and treatments:

• Code 0: Healthy tissues (No treatment).
• Code 1: Bleeding (Oral hygiene instructions, O.I.).
• Code 2: Calculus or overhangs (O.I. + Professional scaling).
• Code 3: 4-5 mm pockets (O.I. + Scaling + Complex periodontal therapy).
• Code 4: Pockets $≥ 6\,mm$ (Same as Code 3).

The Periodontal Screening & Recording (PSR) shares criteria with CPITN but requires probing all teeth in every sextant. It is used in routine clinical practice and holds medical-legal value. A specific PSR probe has a $0.5\,mm$ ball tip and a black band between $3.5\,mm$ and $5.5\,mm$. An asterisk (*) is added to indicate furcation involvements, tooth hypermobility, mucogingival problems, or recessions exceeding the $3.5\,mm$ mark. The black band visibility determines the codes: 0, 1, and 2 mean the band is fully visible; Code 3 means the band is partially covered; Code 4 means the band disappears under the margin (pocket $> 5.5\,mm$).

Advanced Periodontal Assessments

Furcation defects are measured using the curved Nabers probe with $3\,mm$ markings. The horizontal classification by Hamp et al. includes: F0 (Not accessible), F1 (Probing up to $3\,mm$), F2 (Probing over $3\,mm$ but not through), and F3 (Through-and-through). The vertical classification by Tarnow and Fletcher measures the distance from the furcation roof to the bone: Class A ($1-3\,mm$), Class B ($4-6\,mm$), and Class C ($> 6\,mm$).

Tooth mobility is evaluated using Mühlemann's scale by pressing the tooth with two rigid instruments: Grade 0 (None/physiological), Grade 1 (Moderate horizontal movement of $1-2\,mm$), Grade 2 (Severe horizontal movement $> 2\,mm$), and Grade 3 (Gravest; both horizontal and vertical movement).

Gingival recessions are classified by Miller into 4 classes based on the mucogingival line (MGJ): Class I (Vestibular recession not reaching the MGJ, papillae intact), Class II (Reaches or passes MGJ, papillae intact), Class III (Extends to alveolar mucosa with partial papilla/bone loss), and Class IV (Severe loss of attached gingiva and total interproximal bone/papilla collapse).

Dental Erosion and the BEWE Index

Dental erosion is the chemical dissolution of tooth structure due to acids without bacterial involvement, often worsened by mechanical abrasion. Intrinsic causes (endogenous) include gastric acids from gastroesophageal reflux, hiatal hernia, bulimia, or anorexia. Extrinsic causes (exogenous) include acidic foods and beverages like sodas, citrus fruits, or wine. Management involves a multidisciplinary medical approach for intrinsic causes and nutritional counseling for extrinsic ones, alongside desensitizing therapy or restorative rehabilitation.

The Basic Erosive Wear Examination (BEWE) standardizes the diagnosis of erosive wear. The dentition is divided into 6 sextants: 1 (17-14), 2 (13-23), 3 (24-27), 4 (47-44), 5 (43-33), and 6 (34-37). The highest score per sextant is recorded: 0 (No loss), 1 (Initial microstructure loss), 2 (Hard tissue loss $< 50\%$ of surface), and 3 (Hard tissue loss $> 50\%$ of surface). The total score (sum of the 6 sextants) determines risk: $0-2$ (None), $3-8$ (Low), $9-13$ (Medium), and $≥ 14$ (High susceptibility).