Periodontal Index

The periodontal examination was conducted by study nurses supported by experienced dentists. Study nurses received a two week intensive training and calibration for these examinations. 250 individuals were examined both by study nurses and dentists. The agreement between both was good: ~95% agreement regarding pocket probing depths between study nurses and dentists on examined sites (N = 6125 out of 6394) within an error range of + −2 mm was present.
Pocket depth (PD) was used as main indicator for the presence of periodontal inflammation. A full-mouth registration for periodontal status was conducted in Heidelberg and a half-mouth registration was carried out in all other study centers. PD was measured on at least two sites per tooth (mesial and mediobuccal) on maxillary and mandible part. For the examination a UNC-PCP15 Color-Coded Probe (Hu-Friedy Europe, Rotterdam/Netherlands) with a black band for each millimeter up to 15 millimeter was used. According to the Community Periodontal Index for Treatment Needs (CPITN) [39 (link)] for PD the following definition for periodontitis was used: PD 0-3 mm as no/mild periodontitis, at least one pocket ≥4 mm and <6 mm as moderate and with at least one pocket ≥6 mm as severe periodontitis.
Bleeding on probing (BOP) was measured according to Lang et al. [40 (link)] in all study centers except Greifswald. After measuring the PD, the corresponding sites (buccal and mediobuccal) were inspected for the presence or absence of bleeding and noted in an evaluation chart. The absence of BOP can serve as a predictor of periodontal stability [40 (link)]. If the percentage of sites with BOP for each person was less than 30% of all probed sites, it was defined as local bleeding only. A percentage of 30% of sites or higher was considered as general BOP [41 (link)].
Additional dental status parameters (crowns, implants, dentures, missing teeth, caries and bridges) were recorded for full mouth in all centers, except Berlin, where half mouth assessment was performed. In case of these dental parameters data for Berlin were adjusted to full mouth to allow comparisons with the other centers. Caries was assessed as defined by the International Caries Detection and Assessment System (ICDAS) Code 3 as established decay [42 (link)]. Mean numbers were calculated for each dental parameter.

The study protocol was approved by the Helsinki Health Centre Research Coordination Committee. Because the investigation involved only the review of patient records obtained during the course of medical care, no patient consent was required.
Data were collected from the dental records of 100 consecutive patients aged 40 years or older, who had been referred to the University Dental Clinic, Health Centre of Helsinki, for treatment of advanced chronic periodontitis during 2004–2005. Each patient was assigned an encrypted code linking the research data to the patient documents. Subjects with more than 14 teeth were included in the analysis. Patients using statins were compared with those who did not use statins.
We extracted the following data from the patient records: age, gender, reported current smoking, and use of statin medication. In addition, the records were checked for other medications, diabetes, rheumatoid diseases, and indicators of periodontal health.
A visible plaque index for index teeth [20 (link)] was extracted from the records.
For all teeth, we extracted recordings of six periodontal Probing Pocket Depth (PPD) values, measured to the nearest millimetre, from mesiobuccal, midbuccal, distobuccal, distolingual, midlingual, and mesiolingual surfaces using a WHO periodontal probe. [21 (link)-24 (link)]. Data on bleeding on probing was recorded for index teeth only and not included in the study. For a full dentition of 28 teeth, this yields 168 measurements. A gingival sulcus is considered physiological when PPD is less than 4 mm. The number of sites with moderate periodontal lesions (PPD at least 4 mm and less than 6 mm, modPPD) and advanced periodontal lesions (PPD 6 mm or deeper, advPPD) were recorded separately. For a dentition of 28 teeth, both of these indicators yield a maximum value of 6 × 28 = 168.
A novel index, Periodontal Inflammatory Burden Index or PIBI, was derived from the PPD values. The index is calculated by adding the number of periodontal sites indicating moderate periodontitis (N_modPPD) to the weighted number of periodontal sites indicating advanced periodontitis (N_advPPD).



If all measurement sites are advPPD in a 28-tooth dentition, PIBI can reach a maximum value of 336.

One of four dentists (SM, DE, KI, or TA) recorded the oral health status of participants. The DMFT score was used to evaluate dental caries status based on the World Health Organization caries diagnostic criteria
[20 ]. Periodontal condition was assessed using the Community Periodontal Index (CPI)
[20 ]. Ten teeth were selected for periodontal examination: two molars in each posterior sextant and the upper right and lower left central incisors. Measurements were made using a CPI probe (YDM, Tokyo, Japan) at six sites (mesio-buccal, mid-buccal, disto-buccal, disto-lingual, mid-lingual, and mesio-lingual) per tooth. The percentage of teeth exhibiting bleeding on probing (%BOP) was calculated
[21 (link)]. BOP is an earlier and more sensitive indicator of inflammation than probing pocket depth or visual signs of inflammation (redness and swelling). Thus, we assessed %BOP as an indicator of periodontal disease or gingivitis in this study
[21 (link)]. The level of dental plaque and calculus was assessed using the Oral Hygiene Index-simplified (OHI-S)
[21 (link)]. The index has two components: Debris index-simplified and Calculus index-simplified. The degree of debris and calculus deposition was graded on a numeric scale from 0 to 3, divided by the number of sites recorded. The areas examined were the buccal of upper first molar, upper right incisor, and left incisor, and the lingual of lower first molar. Intra- and inter-examiner agreement for the oral examination (score of DMFT and probing pocket depth) was good, as indicated by kappa statistics of more than 0.8.
For malocclusion, a modified version of the Index of Orthodontic Treatment Need (IOTN) was used for each participant. A previous study suggested that the modified IOTN is useful for screening malocclusion by non-specialists in oral health surveys
[22 (link)]. The dental health component of the modified IOTN consists of a two-grade scale (0 = no definite need for orthodontic treatment and 1 = definite need for orthodontic treatment) with no subcategories. The four dentists, who are not orthodontists, assessed the modified IOTN. In a preliminary check, the kappa value was more than 0.80.

After preliminary screening of personal medical history and oral examination at baseline, the participants were randomly assigned to one of the intervention groups: the toothbrush + oral irrigator group (test group) received an OI (WaterPik^® ION Professional Cordless Water Flosser, marketed as GT17 on this region, WaterPik, Inc., Fort Collins, CO, USA) with a uniform standard manual toothbrush (Crest^® Multicolored Crystal Soft Bristles, Procter and Gamble Co., Cincinnati, OH, USA) and a toothpaste (Crest^® Anti-Cavity and Enamel Repair Toothpaste, Procter and Gamble Co., Cincinnati, OH, USA); the toothbrush group (control group) received an identical toothbrush and toothpaste. The OIs allowed for 10 adjustable water pressure settings ranging from 10 to 100 psi, which corresponded to 10 different switches. At baseline, the participants in the test group were instructed to use the OIs in the clinic for the first time by an experienced dental assistant. Furthermore, they were instructed to use the standard jet tip to flush the gingival margin and interdental space twice a day for approximately 90 s before toothbrushing. According to the manufacturer’s recommendations, the participants were advised to adopt the most comfortable water pressure level with a minimum of four. In addition, all participants were instructed to perform manual toothbrushing twice a day with the modified Bass technique. Participants were distributed electronic diaries to record the frequency of toothbrushing and oral irrigation and any adverse reactions or discomfort symptoms. Compliance was evaluated based on the diaries, and it was defined as toothbrushing or oral irrigation ≥ 2 × daily in >80% of study days. Instruction leaflets with toothbrushing methods and oral irrigation instructions were distributed to participants, and they were advised not to use other oral hygiene adjuncts, such as dental floss, interdental brush, and gum.
Before every clinical examination, all participants were instructed to refrain from oral hygiene for 12 h and fast for solids and liquids for 2 h. A single trained examiner evaluated all gingival inflammation-related indices. The MGI [27 ] were examined at four sites (mesial buccal, buccal, distal buccal, and lingual) per tooth. The Bleeding Index (BI) [28 (link)] and percentage of sites with bleeding on probing (BOP%) were examined at six sites (mesial buccal, buccal, distal buccal, mesial lingual, lingual, and distal lingual) per tooth using community periodontal index (CPI) probes. Another trained examiner evaluated the Turesky-Modified Quigley-Hein Plaque Index (T-QH) [29 (link)] after applying the dental plaque disclosing agent. Furthermore, a series of safety observation indicators were evaluated. Gingival recession is defined as apical migration of the gingival margin, and clinically visible sites of gingival recession were examined and recorded. The VAS was adopted to assess the pain and dentin hypersensitivity symptoms during the trial [30 (link)]. The left end of the line segment is marked for no pain or sensitivity symptoms, while the right end represents the most severe pain or sensitivity symptoms. The participants were instructed to mark the line segment according to their existing symptoms during the last month. In addition, vital signs of allergic reactions or lesions in the soft tissue of the oral cavity, including the gingiva, buccal mucosa, lips, palate, vestibular sulcus, tongue, and floor of the mouth, were recorded.
Participants returned to the clinical research center for dental examination at 4 weeks ± 3 days, 8 weeks ± 3 days, and 12 weeks ± 3 days after baseline examinations. The T-QH and gingival inflammation-related indices, including MGI, BI, and BOP%, were reevaluated. Furthermore, the safety indicators were also recorded. The modified Bass technique and the method of OIs use were reinforced at each visit by the same dental assistant. The primary outcomes were gingivitis-related indices after 12 weeks of using OIs. The secondary outcomes were plaque-related indices and gingivitis-related indices at 4 weeks and the safety indicators.

Periodontal health status was evaluated based on the Community Periodontal Index (CPI) [17 (link)]. A total of 10 predetermined teeth (16, 17, 11, 26, 27, 31, 36, 37, 46, and 47) were each assigned the following scores: 0 (healthy periodontal condition); 1 (gingival bleeding); 2 (calculus and bleeding); 3 (shallow periodontal pockets 4–5 mm in depth); and 4 (deep periodontal pockets with a depth of 6 mm or more). The highest score was recorded as the individual’s CPI score.
The CPI scores were then used to score participants’ periodontal assessments using the World Health Organization Community Periodontal Index probe: participants were categorized as having severe periodontitis if the CPI score was 4, and moderate periodontitis if the CPI score was 3. CPI scores of 0, 1, or 2 indicated the absence of periodontitis. Periodontal health status was dichotomized as either with/without moderate periodontitis (CPI Code ≤ 2/≥3) or with/without severe periodontitis (CPI Code ≤ 3/4).

Periodontal assessments were carried out through the Community Periodontal Index (CPI) [11 ]. The measurements were performed through the walking probing method with a 0.5 mm ball-tipped CPI probe, and the examiners were calibrated to apply approximately a 20 g probing force.
The dentition was divided into six sextants represented by the following tooth numbers (FDI system): 18–14, 13–23, 24–28, 38–34, 33–43 and 44–48. A sextant was examined in case two or more teeth unscheduled for extraction were present. For the examination, ten index teeth were used: #17, #16, #11, #26, #27, #37, #36, #31, #46, #47 (FDI system). If a sextant missed one of the index teeth, an adjacent tooth was examined. In case no adjacent tooth was present, all the remaining teeth of that sextant were considered for examination.
The CPI ranged between 0 and 4, as follows: 0 (healthy), 1 (gingival bleeding after probing), 2 (calculus), 3 (probing pocket depth-PPD-between 3.5 and 5.5 mm) and 4 (PPD > 5.5 mm). Each sextant scored as high as its highest score.
For the current analysis, the periodontal status at the participant level was dichotomized as follows:-

Periodontitis case definition:

“No periodontitis” (CPI ≤ 2 in all sextants);

“Periodontitis” (CPI ≥ 3 in at least one sextant).

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Severe periodontitis (deep pocketing) case definition:

“No severe periodontitis” (CPI ≤ 3 in all sextants);

“Severe periodontitis” (CPI = 4 in at least one sextant).