The Periodontal Disease Index (PDI)

The Periodontal Disease Index (PDI) BY SIGURD P. RAMFJORD* THE PERIODONTAL Disease Index is a clinician's modification of Russell's PI index for epidemiological surveys of periodontal disease. The PDI index is primarily concerned with an accurate assessment of the periodontal status of the individual person. Emphasis is placed on recording of the attachment level of the periodontal tis- sues relative to the C-E junction. Such accurate measurable assessments are essential for longitudinal studies of periodontal disease and as a scientific basis for clinical trials in Periodontology. Objectives of the PDI Index The following objectives were incorpo- rated into the design of the index: 1. To assess prevalence and severity of gingivitis and Periodontitis within the individual dentitions and in population groups. 2. To provide an accurate basis for inci- dence and longitudinal studies of periodontal disease. 3. To provide a meaningful basis for es- S. Ramfjord presenting. timate of need for periodontal therapy in selected groups. population ods. Accuracy and reproducibility of scor- 4. To provide accurate recordings for ing becomes increasingly more dependent clinical trials of preventive and therapeutic on the training of the person who is going procedures in periodontics. to do the scoring as demands for accuracy are increased, and the merits of this index 5. To measurable reference data provide should not be evaluated until a person has for assessment of correlations with factors had considerable training and experience of in the of potential significance etiology in the use of the system. Assessment of de- disease. periodontal gree of periodontal disease includes a sub- assessment of Scoring Methods jective color, form, density, and bleeding tendency of the gingival tis- In the 20 minutes allowed me for this sues. But by far the most important feature presentation I will mainly confine my re- of the PDI index is measurement of the marks to clarification of the scoring meth- level of the periodontal attachment related to the C-E junction of the teeth. The loca- tion of the reference marks needed for the *The University of Michigan School of Dentistry, Ann Arbor, Michigan. measurements however is based on touch Page 30/602 Periodontal Disease Index Page 31/603 rather than on vision, which means that the Since all these criteria are based on sub- investigator has to be trained to locate the jective values and examiners judgment I C-E junction and the bottom of the epi- would like to describe in detail the basis thelial attachment accurately by touch. If for such judgment. The gingivae around these reference marks are covered over by the teeth to be scored are first dried super- calculus they have to be exposed. In a few ficially by gently touching with absorbing instances the original cementum-enamel cotton. Changes in color are evaluated by junction may have been lost due to exces- observing the color of the gingiva around sive abrasion or dental restorative proce- the tooth to be scored and comparing the dures. However, in the great majority of color corresponding to the buccal, lingual individuals the cementum-enamel junction and interproximal surfaces with each other, can be located by a well trained investi- as well as comparing it with the color of gator. It should be emphasized that this the gingiva around adjacent teeth. We pay method is entirely unreliable in the hands more attention to the uniformity or lack of of an untrained investigator. uniformity of color than to color shades or hues, since we assume that the physiologic Maximal accuracy also depends on stand- factors which determine different color ardized optimal lighting and standardized shades of gingiva are constant around the thickness of the measuring probes. Only 6 tooth and for the adjacent teeth. Color selected teeth are scored for assessment of changes are usually towards redness but the periodontal status of the mouth; how- there may also be changes towards a bluish ever, for short term clinical trials and or purplish hue. where a limited number of patients are in form is a or available, one may concern all of the teeth Change initially blunting of the of the and in the mouth. The 6 selected teeth are: rounding margin gingiva is tooth #3 (maxillary right first molar), thickening of papilla; however, gingivitis tooth #9 (maxillary left central incisor), never scored on the basis of a slight con- tooth #12 (maxillary left first bicuspid), tour change alone since this may not neces- tooth #19 (mandibular left first molar), sarily indicate the presence of disease. Very tooth #25 (mandibular right central in- little significance is given to the presence or since this cisor) and tooth #28 (mandibular right absence of stippling does not or of first It has been shown by necessarily relate to presence absence bicuspid). inflammation. Jamison and in a number of published and gingival studies from our own institu- unpublished of consistency or density is de- tion that these 6 teeth basis for a Change provide tected pressure with the accurate assessment of the to- by applying gentle surprisingly side of the periodontal probe against the tal periodontal status of the individual as gingiva to determine if there is a soft or expressed in scoring of all of the teeth. spongy consistency. If there is a clearly de- tectable color change indicating gingivitis, status is scored first. The The gingival the consistency is not tested. Any minor method and the value assigned represents change either in contour, stippling or con- a combination of the PMA and essentially alone is not considered to be a defi- definitions sistency the PI index, with the following nite manifestation of gingivitis. of criteria: The score of 3 is based on evidence of 0 = absence of of inflammation signs with if 1 mild to moderate inflammatory gingival ulceration of the gingiva bleeding, — changes, not extending around the tooth the gingiva is touched gently with the side 2 = mild to moderately severe gingivitis ex- of a periodontal probe, or if there is severe tending all around the tooth redness and marked change in contour. The 3 severe gingivitis characterized by score even if — of 3 is these do marked redness, swelling, tendency to given changes bleed and ulceration. not extend all around the tooth. Page 32/604 Ramfjord The next step in the scoring procedure the fingertips becomes impaired. The probe is recording of crevice depth related to the should always be pointed towards the apex C-E junction. For this purpose we use a of the tooth or the central axis of multi- University of Michigan # 0 probe, made by rooted teeth. After the distance from the the Premier Mfg. Co. in Philadelphia. We free gingival margin to the cementum have encountered great problems in stand- enamel junction has been measured, an at- ardizing the manufacturing of this probe tempt should be made to move the probe and it still is not the instrument that we along the cemental surface. This of course would like to have. We have had problems can be achieved only if there has been loss with variation in thickness, with inaccurate of periodontal attachment. If calculus cov- placement of the reference marks, varia- ers the cementum enamel junction it has to tions in clarity of definition of the reference be removed before the C-E junction can be marks, and variations in angulations. Be- localized. Occasionally it is also necessary sides the obvious errors that can result to remove heavy deposits of supragingival from variation in placement of the refer- calculus to gain access to the gingival crev- ence marks, a slight variation in thickness ice. The University of Michigan #0 probe may influence the results when populations is graduated at 3, 6, and 8 mm. from the with fairly normal and dense gingival tis- end, making it necessary to estimate inter- sues are scored. A thin probe under these vening measurements. In our experience, circumstances will penetrate deeper than a reproducibility is better and eye strain less thicker probe and consequently give higher following proper training with this probe scores. than with probes that have marks for every mm. The probe should be held with a light grasp similar to the manner of holding a All measurements are rounded to the pencil and balanced well in the hand so it nearest mm.; except that anything close to can be moved and directed by very small Vi a mm. is always rounded to the lower forces. The end of the probe should be whole number. It has been found in our placed against the enamel surface coronally combined histometric and clinical studies to the margin of the gingiva so that the that there is a tendency with a thin probe angle formed by the working end of the to record a slightly greater depth than to probe and the long axis of the crown of the the coronal level of the connective tissue tooth is approximately 45°. A minimal force attachment to teeth. Thus we do not re- should be used to pass the probe in apical cord for instance 1 mm. of pocket depth direction maintaining contact with the below the C-E junction and indicate loss of tooth. The angle between the probe and attachment unless we are sure that the the tooth may have to be decreased slightly probing extends definitely more than Vi when the probe touches the gingiva to mm. from the C-E junction. By assigning avoid pressure on the gingiva when the all the doubtful measurements to the lower probe is inserted in the gingival crevice. score the reproducibility is much greater than if a more accurate determination of Since the surfaces of the enamel and Vx mm.

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