|Year : 2022 | Volume
| Issue : 1 | Page : 45-50
Evolution of Indices in the Screening of Periodontal Diseases: A Narrative Review
Danavanthi Bangera1, Krishnan Vishwanathan2, Jayadevan Sreedharan3, Prabhu Manickam Natarajan4
1 Department of Dental, Thumbay Dental Hospital, Ajman, UAE
2 Department of Periodontics, Rajah Muthiah Dental College and Hospital, Annamalai University, Chidambaram, Tamil Nadu, India
3 Department of Community Medicine, Gulf Medical University, Ajman, UAE
4 Department of Periodontics, College of Dentistry, University of Science and Technology of Fujairah, Fujairah, UAE
|Date of Submission||02-Jan-2021|
|Date of Decision||20-Mar-2021|
|Date of Acceptance||16-Apr-2021|
|Date of Web Publication||31-Dec-2021|
Thumbay Dental Hospital, Ajman
Source of Support: None, Conflict of Interest: None
Periodontal disease is the inflammation of the periodontal supporting structures of teeth. An index is an important tool of surveillance system based on the requirements of reliability, simplicity, and validity to screen oral health disease of the population. This paper aims to discuss on various indices formulated to measure periodontal disease from past to present. This paper reviews indices and different recording systems used to measure periodontal diseases at the population level by retrieving articles, selecting, writing, and summarizing the article. The advantages and disadvantages of various indices used for measuring periodontal disease are discussed in this article. Community Periodontal Index is the most widely accepted index used in larger research studies. However, presently, clinical attachment loss is a widely accepted tool for the diagnosis of periodontal disease. Future advances in new screening methods will be able to provide new opportunities in the diagnosis of active and progressive periodontal disease, which will further help in more precise screening of periodontal disease in larger research studies.
Keywords: Indices, periodontal diseases, periodontal index
|How to cite this article:|
Bangera D, Vishwanathan K, Sreedharan J, Natarajan PM. Evolution of Indices in the Screening of Periodontal Diseases: A Narrative Review. Indian J Dent Sci 2022;14:45-50
|How to cite this URL:|
Bangera D, Vishwanathan K, Sreedharan J, Natarajan PM. Evolution of Indices in the Screening of Periodontal Diseases: A Narrative Review. Indian J Dent Sci [serial online] 2022 [cited 2022 Aug 19];14:45-50. Available from: http://www.ijds.in/text.asp?2022/14/1/45/334516
| Introduction|| |
Periodontal disease is the inflammation of the periodontal structures which may lead to loss of the connective tissue, migration of junctional epithelium, and alveolar bone loss., Periodontal disease includes activation of osteoclastogenesis followed by irreversible destruction of alveolar bone, leading to loss of tooth support. Prevalence of mild and moderate forms of periodontal disease is around 50% and is more seen in the adult population, while around 10% of disease is in severe form. The prevalence and incidence rate of periodontal diseases vary due to case misclassification, bias, and number of teeth and sites examined. Canadian Health Measures Survey conducted in 2007–2009 considered measurement of loss of attachment of periodontal ligament as the gold standard in reporting the prevalence of periodontal disease.
Epidemiological studies on periodontal disease (Al Bander JM, 2005) have shown various symptoms such as gingivitis, pocket depths, and clinical attachment loss (CAL) and alveolar bone loss shown in radiographs. Various indices have been formulated based on the understanding of etiology and progression of the disease and used to evaluate periodontal disease, however there is still lack of data on these indices based on their evolution, merits, and demerits.
This paper aims to discuss on various indices formulated to measure periodontal disease from past to present. This paper reviews indices and different recording systems used to measure periodontal diseases at the population level by retrieving articles, selecting, writing, and summarizing the article.
| Characteristics of Indices for Periodontal Disease|| |
The main characteristics of the index used for clinical studies are validity and reliability of the tools, and epidemiological approaches to measure periodontal disease are based on clinical assessment measured by using a periodontal probe with precise measurements. Major concerns were:
- Index teeth and their sites to be tested around tooth
- Precision of the measurements
- Case definition of periodontal disease.
| Index Teeth and Their Sites to be Tested Around Tooth|| |
Probability sampling of relevant teeth and sites that provides the most accurate representation of the disease would be appropriate at the population-level survey. However, partial recording reported bias and underestimation of the disease. National Health and Nutrition Examination Survey (NHANES) survey (2009–2012) includes the total examination of all sites and teeth to overcome bias and underestimation of the periodontal disease.
| Precision of the Measurements|| |
Precision of the measurements depends on dexterity of the examiners at performing the measurements, training and repetition. Debate in the use of World Health Organization (WHO) probe in the Community Periodontal Index of Treatment Needs (CPITN) and Community Periodontal Index (CPI) is between more precise and with less reliability versus less precise, but measurements with more reliability and the choice vary between clinicians and epidemiologists.
| Case Definitions|| |
Case definition of periodontal disease is an essential prerequisite of an epidemiological study of the disease. In early epidemiological study, Periodontal Index (PI) evaluated the presence or absence of inflammation and periodontal pockets. Earlier, periodontal disease was described as normal or mild gingivitis, or severe gingivitis with periodontal pocket, or periodontitis with tooth mobility. Various case definitions for periodontal diseases have been suggested which combine loss of attachment with or without pocket depths in a specific number of sites and teeth. Following are the case definitions based on these measurements:
- Burt and Eklund, 1992, defined periodontal disease as when 4 or more sites with ≥5 mm or 2 or more sites with ≥6 mm of CAL, with probing depths of ≥4 mm or ≥5 mm respectively at one or more of those sites
- In 5th European Workshop by Tonetti et al. in 2005, periodontal disease was defined as loss of periodontal attachment of ≥3 mm in 2 or more nonadjacent teeth or ≥5 mm in ≥30% of teeth present
- According to CDC and American Academy of Periodontology (AAP), periodontal disease was classified as severe, moderate, and mild; severe: when 2 or more interproximal sites with ≥6 mm of loss of attachment and one or more interproximal sites with probing depths of ≥5 mm, moderate: 2 or more interproximal sites with ≥4 mm of loss of attachment, and mild: 2 or more interproximal sites with ≥3 mm of loss of attachment.
| Discussion|| |
History of indices
Various indices have been developed to evaluate periodontal diseases over the years, and the advantages and disadvantages of various indices used for measuring periodontal disease are discussed in the following paragraphs, which are also summarized in [Table 1].
Evolution of indices from 1955 to 1988
The Recession Index was the initial PI developed by Stahl and Morris in the year 1955 to find out the difference in the extent and severity of the gingival disease between people from different geographical locations. It measured the number of teeth with exposed cementum. It measured only the presence of supragingival calculus, not the inflammation of periodontal tissues.
Russell's Periodontal Index
Russell formulated PI in 1956, the first index for periodontal disease. It measured the presence and severity of gingival inflammation as well as pocket depth. Russell collected data and used PI as a survey tool in which all teeth were examined. Russell created the index with scoring criteria (0, 1, 2, 6, 8) based on the presence of inflammation, pocket formation, and loss of function. In 1967, Russell modified PI in the form of treatment needs. PI scores in the range from 0.1 to 8.0, with the treatment required ranging from prophylaxis to total extraction.
Russell's PI was easy, was simple to use, had clear criteria of treatment required for each score level, and was able to measure discrepancies between different community groups. However, the PI was flawed methodologically and conceptually, due to the concern of its validity, reliability, and failure to consider gingivitis equivalent to early periodontitis.
Periodontal Disease Rate Index
In 1959, periodontal disease rate Index was developed by Sandler and Stahl that assessed each tooth radiographically and clinically by measuring mobility, pocket depth, and gingiva and categorized as affected or not affected.
In 1966, Ramfjord formulated Periodontal Disease Index (PDI). PDI scored gingival status 0–3 scale, while the loss of attachment was measured on a scale from 4 to 6 on index teeth. In contrast to Russell's PI, Sigurd Ramfjord's PDI used a probe with markings at 3, 6, and 8 mm that measured the pocket depth. These markings improved the reliability of the tool. Six “index teeth” (Ramfjord teeth), as per FDI (Federation Dentaire Internationale) were: 16, 21, 24, 36, 41, and 44. Measurements initially were made on four sites, but later were modified to include only mesial and mid-buccal sites.
The main advantages were, it provides an accurate evaluation of periodontal status and easy calibration. However, it requires high precision and time consuming. In one of the epidemiological studies conducted in India, PDI reported lower disease levels when compared with radiographic methods.
Gingival Bone Count Index
In 1960, Gingival Bone Count Index was developed by Dunning and Leach, in which composite score is formulated by combining comparative measurements of bone loss interpreted through radiographs and subjective measurements of gingival status. It can be used as a cumulative index. It is time consuming as it includes both, intra-oral examination and radiographs interpretations and thus is not extensively used.
Gingival periodontal index
In 1967, O'Leary formulated GPI, in which teeth were divided into six sextants as per Federation Dentaire Internationale (FDI) notation: teeth 17–14, 13–23, 24–27, 37–34, 33–43, and 44–47. The highest score in each sextant was recorded at mesiobuccal line angle, for gingival was 0–3 and for periodontal was 4–6 and then scores were added and sum was divided by the number of sextants to obtain an individual score of GPI.
The main advantage was that it improved the patient's oral health status and the scores determined the treatment need of the patients. Methodology of the index has been used in some studies by Rajapakse et al., 2005. Modification of this index measured only pocket depth and has been used in various oral health surveys.
Navy Periodontal Disease Index
In 1974, Navy Periodontal Disease Index was formulated by Grossman and Fedi to aid in early identification and diagnosis of periodontal disease. Score from gingiva (0–2) and pocket score (0, 5, and 8) of the six Ramfjord teeth were added to derive the NDPI score. A survey conducted by Hancock and Wirthlin among 98 young adults found that NDPI total provided clinician a wide range of scores that would provide an early indication of the level of involvement.
Periodontal Status Index
Periodontal Status Index was developed by the WHO in 1971 that measured oral hygiene status and periodontal condition by combining Russell's PI and Oral Hygiene Index. But, it was soon replaced by the CPITN.
Community Periodontal Index for Treatment Needs
CPITN was formulated by WHO in 1982 with the objective to provide measurement at international level. It measured bleeding of the gingiva, presence of calculus, and pocket depth with the help of WHO probe with 0.5 mm ball tip, a black band between 3.5 and 5.5 mm and marks at 8.5 and 11.5 mm. CPITN then developed a prototype index-the technical report series 621 method by exclusion of Ramfjord's teeth and was used in oral health epidemiological surveys in 1983.
In epidemiological surveys, individual's treatment needs was determined by recording the highest scores in each sextant resulting in six scores. CPITN was used worldwide as it was simple, fast, and internationally unified. A study conducted in 2009 by Muthukumar and Suresh showed sensitivity (92.86%) and specificity (80%); indicating the validity of CPITN in assessing anaerobic periodontal infection. However, there are limitations compiled by Baelum and Papapanou, 1996 which include:
- CPITN is a hierarchical measurement which is not universally valid
- CPITN used in partial surveillance systems which may lead to underestimation of disease
- CPITN sometimes provides over and underestimation of the periodontal disease in a population.
The WHO then introduced some modifications to the CPITN in 1987 and 1997 due to the limitations identified.
Periodontitis Severity Index
In 1986, Periodontitis Severity Index (PSI) was introduced to assess the presence of periodontitis by detecting inflammation through clinical examination and alveolar crestal bone loss through radiographs using a Schei ruler. Advantages of this index are ratio data can be obtained between healthy sites and diseased sites and direct measurements of severity of the periodontal disease can be obtained. Drawbacks are the requirement of follow-up radiographs and also radiographs do not provide buccal and lingual bone loss calculations. Thus, PSI was only be used in longitudinal studies and lacks validation.
Extent and Severity Index
In 1986, Carlos et al. formulated Extent and Severity Index which measured the extent and severity of the disease. Extent and Severity Index (ESI) measured loss of attachment in all teeth of randomly selected one maxillary and one mandibular arch except for the third molars. The extent score is measured by the percentage of attachment loss >1 mm and the severity score is the average of attachment loss per site. ESI for population is calculated by taking the average of the individual scores. It is a simple and reliable method which provides information on periodontal status and requires minimal training. However, ESI provides partial and inaccurate scores as it measures only 28 sites in contralateral quadrants. Hunt and Fann reported that ESI provides proportional underestimation in cases with higher severity and lower prevalence of periodontitis.
Periodontal Screening and Recording Index
Periodontal screening and recording (PSR) was formulated by the AAP in 1988 and American Dental Association. This modified CPITN procedure became highly popular for periodontal screening in the USA and Canada. PSR index is recorded by using plastic PSR probe which has 0.5 mm diameter ball tip and a color-coded band extending 3.5–5.5 mm from the tipand determining greatest score in each segment out of six segments. The advantages of the PSR index are speed and simplicity. However, PSR can underestimate the disease and also the asterisk code which indicates furcation involvement, mobility or recession, lack to specify the process to detect periodontal disease.
Recent evolution of indices from 1997 to 2007
Community Periodontal Index
In 1997, the CPITN index was modified to CPI by measuring only CAL and eliminating treatment needs scoring. In this index, 10 teeth i.e. 17, 16, 11, 26, 27, 37, 36, 31, 46, and 47 were assessed and evaluated for the presence of bleeding, calculus, probing depths between 3.5 and 6.0 mm, as well as CAL measured with WHO probe. The inclusion of loss of clinical attachment eliminates the false scoring of pseudo pockets. CPI is useful in research studies with larger group of study population and is also useful in preventive and treatment methods, it allows the identification of risk factors of disease onset and progression. However, the CPI has been criticized for using an old model to measure disease and the validity of the sequence of clinical changes such as gingival bleeding, calculus, and periodontal pocket is also questioned. A study conducted in India to determine the prevalence of periodontal disease in 2014 reported that using CPITN as an index tool has limitation to be considered as a case definition for periodontitis. CPITN measures the prevalence of persons requiring periodontal treatment, not the actual prevalence of extent and severity of the disease.
Albander et al. formulated the Index to assess the prevalence of disease and severity by measuring the probing depth and attachment loss by examining only two randomly selected quadrants (partial recording method). Both numbers and percentages of teeth are used to measure the index as it reduces the underestimation of the disease. However, the index was difficult to implement in epidemiological studies.
Dichotomous Periodontal Index
In this index, periodontal disease is measured as CAL against the reference point. A survey conducted in Canada by Brothwell and Ghiabi in the year 2009 used bivariate analysis to determine dichotomous outcome variables: mean CAL (≤2.5 mm and >2.5 mm) and severe CAL (one or more sites with >5 mm).
Genetic Susceptibility Index
There is transition from “traditional epidemiology” which determines the disease at the community to “modern epidemiology” that determines the disease at individual level (molecular level). Moustakis et al., 2007, formulated Genetic Susceptibility Index (GSI) which assessed single-nucleotide polymorphisms and microbial components of the disease. It explained that the disease occurred due to molecular and genetic behavior of individuals. In a research study conducted among Caucasians by Baelum and Lopez, 2004, GSI derived from genotypes showed that when overall scores is <1, the likelihood towards being healthy is 85% and when it is higher than 4, then there is 88% more likelihood to contract the disease. GSI scores linked with microbial values showed similar probability of periodontal health of an individual.
Evidences have shown that GSI provides confirmation to presence of periodontal disease, however it lacks an operational tool which will make the clinician to use the genetic pattern of the patient in medical decision-making and reasoning.
| Developmental Perspectives|| |
Periodontal indices formulated so far have their own advantages and disadvantages. Indices so far measure the extent of past periodontal diseases but no indication of present disease activity. The development of an index that quantifies the incidence of present periodontal disease activity is essential.
CAL is the optimum tool to measure periodontal disease, however probing requires well-trained examiners, it is time consuming, and requires good compliance from the participants. Attachment loss and probing depth at six sites of all teeth (excluding third molars) for the evaluation of periodontal disease in NHANES, 2009 and 2010. Loss of periodontal attachment primarily does not measure active inflammation of the disease but it measures the sequelae of the disease. NHANES 2009–2014 used full-mouth periodontal examination protocol for the first time. Greatest CAL measurement usually occurs at an interproximal site which determines the most severely diseased site. Periodontitis can be localized if <30% of the specified sites have CAL and generalized if 30% or more of the sites measures CAL. Loss of clinical attachment of around 3 mm is often considered as the threshold for assessing periodontal disease, however, it might vary considerably between studies and researchers.
Inflammatory biomarkers may provide more accurate representation of active disease as they are based on physiological events than CAL or pocket depth. Biomarkers can also be used in both clinical and epidemiological studies as it is valid, reliable, low examiner error, cost-effective, and acceptable. Studies done by Gursoy et al., 2011, and Kinney et al., 2011, reported that biomarkers detect salivary levels of periodontal pathogens and inflammatory molecules, macrophage protein, and matrix metalloprotease., However, these approaches cannot be applied as effective clinical tools as well as surveillance tools.
Following are the possible options available to formulate new PI:
- Assessing radiographic bone levels along with loss of clinical attachment of the teeth. Digital radiographs help to detect even minor bone level differences between two appointments. Thus, combining both digital radiographs and loss of clinical attachment will be an essential measurement tool in clinical trials. However, practically digital radiographs are difficult in the population-based study as it is expensive, technique sensitive and time consuming
- Measuring the difference of CAL between two appointments will provide information on disease progression but does not predict future destructive events
- Measuring the level of inflammatory biomarkers and host-derived enzymes in gingival crevicular fluid, saliva, or plaque is a possible test to accurately detect active and progressive disease. However, they should be reliable and accurate to be used in the PI system. Bretz et al. used BANA (n-benzoyl-DL-arginine-β-naph-thylamide to detect proteolytic enzymes. After comparing the test results using the ELISA kit, the BANA test showed high sensitivity but lower specificity as compared to ELISA. A study conducted in 2010 reported that the BANA test is an effective method to detect pathogens in the initial diagnosis of chronic periodontitis; however, its use is limited in posttherapy monitoring.
| Conclusion|| |
Periodontal indices have evolved over the years based on the pathogenesis of periodontal disease which have their own merits and demerits. Ideally, an index would be which measures active and progressive disease which will help in identifying early onset of the disease and preventing further progression. It is observed that with the evolution of indices, validity of the indices is increasing.
This review is an attempt to provide cumulative information about the evolution of periodontal indices to general dentists as well as the periodontal community. With the increase in the validity of recently formulated indices, new screening methods will be able to provide new opportunities in the diagnosis of active and progressive periodontal disease, which in further help in more precise screening of periodontal disease in larger research studies.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Dhingra K, Vandana KL. Indices for measuring periodontitis: A literature review. Int Dent J 2011;61:76-84.
Könönen E, Gursoy M, Gursoy UK. Periodontitis: A multifaceted disease of tooth-supporting tissues. J Clin Med 2019;8:1135.
Nazir MA. Prevalence of periodontal disease, its association with systemic diseases and prevention. Int J Health Sci (Qassim) 2017;11:72-80.
Albandar JM. Epidemiology and risk factors of periodontal diseases. Dent Clin North Am 2005;49:517-32, v-vi.
Beltrán-Aguilar ED, Eke PI, Thornton-Evans G, Petersen PE. Recording and surveillance systems for periodontal diseases. Periodontol 2000 2012;60:40-53.
Eke PI, Thornton-Evans GO, Wei L, Borgnakke WS, Dye BA. Accuracy of NHANES periodontal examination protocols. J Dent Res 2010;89:1208-13.
Page RC, Eke PI. Case definitions for use in population-based surveillance of periodontitis. J Periodontol 2007;78 Suppl 7S: 1387-99.
Burt BA, Eklund SA. The methods of oral epidemiology. In: Burt BA, Eklund SA, editors. Dentistry, Dental Practice, and the Community, 4. Philadelphia, PA; W.B. Saunders Company; 1992. p. 64-8.
Tonetti MS, Claffey N, European Workshop in Periodontology Group C. Advances in the progression of periodontitis and proposal of definitions of a periodontitis case and disease progression for use in risk factor research. Group C consensus report of the 5th
European Workshop in Periodontology. J Clin Periodontol 2005;32 Suppl 6:210-3.
Eke PI, Page RC, Wei L, Thornton-Evans G, Genco RJ. Update of the case definitions for population-based surveillance of periodontitis. J Periodontol 2012;83:1449-54.
World Health Organization. Oral Health Surveys. Basic Methods. Geneva: World Health Organization; 1971.
Cutress TW, Ainamo J, Sardo-Infirri J. The community periodontal index of treatment needs (CPITN) procedure for population groups and individuals. Int Dent J 1987;37:222-33.
Muthukumar S, Suresh R. Community periodontal index of treatment needs index: An indicator of anaerobic periodontal infection. Indian J Dent Res 2009;20:423-5.
] [Full text]
Baelum V, Papapanou PN. CPITN and the epidemiology of periodontal disease. Community Dent Oral Epidemiol 1996;24:367-8.
Landry RG, Jean M. Periodontal Screening and Recording (PSR) Index: Precursors, utility and limitations in a clinical setting. Int Dent J 2002;52:35-40.
Ramanarayanan V, Karuveettil V, Sanjeevan V, Antony BK, Varghese NJ, Padamadan HJ, et al.
Measuring dental diseases: A critical review of indices in dental practice and research. Amrita J Med 2020;16:152-8. [Full text]
Antunes JL, Peres MA, Frias AC, Crosato EM, Biazevic MG. Gingival health of adolescents and the utilization of dental services, state of São Paulo, Brazil. Rev Saude Publica 2008;42:191-9.
Moustakis VS, Laine ML, Koumakis L, Potamias G, Zampetakis L, Loos BG. Modeling genetic susceptibility: A case study in periodontitis. In: Combi C, Tucker A, editors. Proceedings of IDAMAP-2007: Intelligent Data Analysis in Biomedicine and Pharmacology, Amsterdam. The Netherlands: Artificial Intelligence in Medicine (AIME) Workshop; 2007. p. 59-64.
Shewale AH, Gattani DR, Bhatia N, Mahajan R, Saravanan SP. Prevalence of periodontal disease in the general population of India – A systematic review. J Clin Diagn Res 2016;10:E04-9.
Dye BA, Thornton-Evans G. A brief history of national surveillance efforts for periodontal disease in the United States. J Periodontol 2007;78 Suppl 7S: 1373-9.
Rajapakse PS, Nagarathne M, Chandrasekra KB, Dasanayake AP. Periodontal disease and prematurity among non-smoking Sri Lankan women. J Dent Res 2005;84:274-7.
World Health Organization, Oral Health Unit. Community Periodontal Index of Treatment Needs. Development, Field Testing and Statistical Evaluation. Geneva: World Health Organization; 1984.
Bassani DG, da Silva CM, Oppermann RV. Validity of the “Community Periodontal Index of Treatment Needs” (CPITN) for population periodontitis screening. Cad Saude Publica 2006;22:277-83.
Borges-Yáñez SA, Maupomé G, Jiménez-García G. Validity and reliability of partial examination to assess severe periodontitis. J Clin Periodontol 2004;31:112-8.
Brothwell D, Ghiabi E. Periodontal health status of the Sandy Bay First Nation in Manitoba, Canada. Int J Circumpolar Health 2009;68:23-33.
Baelum V, Lopez R. Periodontal epidemiology: Towards social science or molecular biology? Community Dent Oral Epidemiol 2004;32:239-49.
Marya CM. Dental Indices. In Textbook of Public Health Dentistry. 1st
ed. New Delhi: Jaypee Brothers Medical Publishers (P) Ltd.; 2011. p. 185-211.
Eke PI, Borgnakke WS, Albander JM. Measurement and distribution of periodontal diseases. In: Burt and Eklund's Dentistry, Dental Practice and the Community. 7th
ed. Elsevier Saunders: Philadelphia; 2020. p. 171-88.
Kamma JJ, Giannopoulou C, Vasdekis VG, Mombelli A. Cytokine profile in gingival crevicular fluid of aggressive periodontitis: Influence of smoking and stress. J Clin Periodontol 2004;31:894-902.
Gursoy UK, Könönen E, Pussinen PJ, Tervahartiala T, Hyvärinen K, Suominen AL, et al.
Use of host- and bacteria-derived salivary markers in detection of periodontitis: A cumulative approach. Dis Markers 2011;30:299-305.
Kinney JS, Morelli T, Braun T, Ramseier CA, Herr AE, Sugai JV, et al.
Saliva/pathogen biomarker signatures and periodontal disease progression. J Dent Res 2011;90:752-8.
Ronderos M, Michalowicz BS. Epidemiology of periodontal disease and risk factors. In: Rose LF, Mealey BL, Genco RJ, Cohen DW, editors. Periodontics: Medicine, Surgery and Implants. 1st
ed. St. Louis, Missouri: Elsevier Mosby; 2004. p. 32-68.
Andrade JA, Feres M, Figueiredo LC, Salvador SL, Cortelli SC. The ability of the BANA Test to detect different levels of P. gingivalis, T. denticola
and T. forsythia
. Braz Oral Res 2010;24:224-30.