Plaque indices

The amount of plaque and tartar can be determined in dental offices using plaque indexes.

General characteristics
The indices can also be used to assess the oral health of the patient and to check the results of therapy. We can find out in which places of the oral cavity inflammatory changes occur and where oral hygiene needs to be improved. In order for the diagnosis to be reliable, certain requirements must be observed:


 * quantitative (or qualitative) information value
 * high sensitivity and specificity
 * high positive/negative forecast value
 * simplicity and reproducibility
 * Fast, practical use and calculation
 * easy to perform by dentists or dental hygienists without special training

We usually evaluate the indices for all teeth, but in certain cases we can limit the examination only to the so-called. Ramfjord's teeth (16, 21, 24, 36, 41, 44), these teeth are representative and the result we get should be the same as for the rest of the teeth. We calculate the index by dividing the measured values or yes/no data by the number of examined sites.

Index = sum of measured values / number of examined places

In addition to indices, the dentist can also use gravimetric procedures (determining the mass of plaque present) and planimetric procedures (determining the area covered by plaque using photographs).

We use various dyes to highlight dental plaque. After staining the spots, the patient must rinse thoroughly and then the dentist will evaluate the stained areas. Food dyes (erythrrosin B, patent blue V) or fluorescent dyes that bond with plaque within a short time are used as dyes. Erythrrosin stains immature plaque red, patent blue stains old, mature plaque blue.

Modified Plaque-index (Quigley, Hein)
This index evaluates the coverage of the crown surface with plaque and is used most often nowadays. Aproximal and sulcular plaque is not adequately evaluated. Before the examination, the areas of the tooth facing the cheek are stained. During the examination, we distinguish six degrees:


 * Grade 0: no plaque
 * Grade 1: Single islets of plaque
 * Grade 2: Unambiguous, continuous line at the edge of the gingiva up to 1 mm width
 * Stage 3: plaque is enlarged in the cervical third of the crown
 * Stage 4: plaque extends to the middle third of the crown
 * Stage 5: plaque extends into the coronary third of the crown

Plaque-index (PlI) (Silness and Loe)
This Plaque-index evaluates plaque involvement and its thickness in the cervical region, taking into account the sulk, tooth surface and gingiva edge. The instruments required for the examination are a mirror and a probe. The examination takes place on all surfaces of the tooth and plaque is not stained. Here there are 4 degrees of disability:

Grade 0: plaque cannot be detected either by inspection or probing

Stage 1: An invisible, thin film of plaque can only be seen by wiping it off with a probe

Stage 2: slight accumulation of plaque, visible to the naked eye, the interdental space is not filled with plaque

Stage 3: Strong buildup of plaque that also fills the aproximal spaces

Modified Approximalraum-Plaque-Index (API)(Lange)
When plaque stains, the dentist only evaluates the presence of plaque in the aproximal space using yes/no. Here the work of the patient and the correct way of oral hygiene are important.


 * API = (sum of positive findings with plaque / sum of assessed proximal spaces) x 100

Hygiene according to API is divided as follows:
 * API 25% corresponds to optimal oral hygiene
 * API 25-39% is indicative of good hygiene
 * API 40-69% corresponds to poorer hygiene
 * API 70-100% indicates insufficient oral hygiene

Plaque-Formations-Rate-Index (PFRI) (Axelsson)
This index is used to quantify the conditions for the formation of plaque. It allows estimation of the individual risk of caries in an individual. The formation of plaque depends on:
 * total number of bacteria in the oral cavity
 * Composition of oral microflora
 * the amount and frequency of intake of fermentable carbohydrates
 * the amount of saliva and its composition
 * anatomy and character of tooth surfaces, fillings and prosthetic work

Twenty-four hours after professional tooth cleaning, plaque is assessed at six defined sites on each tooth. Plaque is stained interobacucally, interlingually, lingually, distobukally, distolingually. The index is given as a percentage.
 * PFRI = (sum of positive plaque findings / number of teeth x 6) x 100

The PFRI is evaluated as follows:
 * PFRI < 10% = Grade 1
 * PFRI 11-20% = Grade 2
 * PFRI 21-30% = Grade 3
 * PFRI 31-40% = Grade 4
 * PFRI > 40% = Grade 5

Grade 3-5 indicates an increased risk of tooth decay.