CS4-5) CLASSIFICATION OF PERIODONTAL DISEASES AND CONDITIONS and Periodontal Disease Epidemiology-Ayşe Çaygür Yoran.pdf

Assist. Prof. Dr.Ayşe ÇAYGÜR YORAN YAKINDOĞU ÜNİVERSİTESİ DİŞ HEKİMLİĞİ FAKÜLTESİ Learning Outcome: 1-Will be able to make the 2017 current classification of periodontal diseases 2- Will be able to define the criteria that determine the staging and grading of periodontitis, and make staging and gr...

Assist. Prof. Dr.Ayşe ÇAYGÜR YORAN YAKINDOĞU ÜNİVERSİTESİ DİŞ HEKİMLİĞİ FAKÜLTESİ Learning Outcome: 1-Will be able to make the 2017 current classification of periodontal diseases 2- Will be able to define the criteria that determine the staging and grading of periodontitis, and make staging and grading. 3- Will be able to explain the risk factors for periodontal diseases. 4- Will be able to explain the indexes used in periodontology and the indexes that determine gingivitis. CLASSIFICATION OF PERIODONTAL DISEASES AND CONDITIONS Classification of Periodontal Diseases Periodontal diseases are one of the most common chronic inflammatory diseases in the world. The main cause of this disease is microbial dental plaque, plaque bacteria themselves or their toxins stimulate host defense cells and cause a wide variety of enzymes and cytokines to accumulate in periodontal tissues. These enzymes and cytokines cause destruction in periodontal tissues over time. Diagnosis; is the first step of treatment. Classification of diseases provides accurate and reliable diagnosis. Classification of diseases; It can be defined as a system of categories consisting of disease names brought together according to precise criteria. In the classification, disease-related data are presented in a form that can be easily evaluated and examined by physicians. Systematic regulation of diseases is necessary in order to obtain a practical and clear diagnosis and to apply an accurate treatment. Many classification systems have been used for periodontal diseases from past to present. Scientific developments cause the classifications used to not meet the needs after a while and new classification systems are created. In the 1989 classification; Clinical findings, age of onset of the disease, rate of progression were used to define the types of periodontitis. American Academy of Periodontology (AAP 1989) 1-Gingivitis 2-Adult Periodontitis 3- Early Settlement Periodontitis A. Prepubertal Periodontitis B. Juvenile Periodontitis C. Rapidly Progressive Periodontitis 4- Necrotizing Ulcerative Periodontitis 5- Intractable Periodontitis 6- Periodontitis associated with Systemic Diseases In 1999, a classification change was made. The reason for this change is that in the 1989 classification, periodontitis types are mainly based on the age of onset of the disease, but the age of onset of the disease is mostly unknown in clinical practice. In the 1999 classification, the rate of progression was taken as the basis instead of the age of onset of the disease, which was taken as the basis in the 1989 classification. (AAP 1999) 1. Gum Diseases 2. Chronic Periodontitis 3. Aggressive Periodontitis 4. Periodontitis as a Symptom of Systemic Diseases 5. Necrotizing Periodontal Diseases 6. Periodontium Abscesses 7. Periodontitis Associated with Endodontic Lesions 8. Developmental and Acquired Deformities The 1999 classification was used for 17 years. Due to the problems encountered in this process, periodontal diseases were reclassified in 2017 by holding a joint world workshop with the European Federation of Periodontology (EFP) and the American Academy of Periodontology (AAP). The reasons for changing the classification; -No findings proving that chronic and aggressive periodontitis are two different diseases as a result of clinical, biochemical and microbiological studies conducted in the 2000s Uncertainty in the diagnosis of aggressive and chronic periodontitis - Absence of pathobiological distinction between periodontitis -The main distinction between the predicted categories is not clear. -Difficulties in diagnostic accuracy -Due to reasons such as application difficulties, a need for a new classification has arisen. As a result of the discussion sessions held during the workshop, chronic and aggressive periodontitis; It has been accepted that there are no two different diseases that differ from each other in terms of disease causes, pathogenic mechanisms and clinical findings, and periodontitis is grouped under three main headings Periodontitis (EFP / AAP 2017) 1.Necrotizing periodontal diseases 2. Periodontitis 3. Periodontitis, a symptom of systemic diseases 2018 CLASSİFİCATİON OF PERİODONTAL AND PERİ-İMPMAT DİSEASES AND CONDİTİONS 1) PERİODONTAL HEALTH, GİNGİVAL DİSEASES AND CONDİTİONS a. Periodontal Health and Gingival Health b. Gingivitis:Dental Biofilm-İnduced c. Gingival Diseases: Non-Dental Biofilm-Induced 2) PERİODONTİTİS a. Necrotizing Periodonal Diseases b. Periodontitis c. Periodontitis as a Manifestation of Systemic Disease d. Periodontal Abscesses and Endodontic-Periodontal Lesions 3) PERİODONTAL MANİFESTATİONS OF SYSTEMİC DİSEASES AND DEVELOPMENTAL AND ACQUİRED CONDİTİONS a. Systemic Diseases or Conditions Affecting Periodontal Supporting Tissues b. Mucogingival deformities and Conditions c. Traumatic occlusal Forces d. Tooth and Prosthesis-Reated Factors 4) PERI-IMPLAN DİSEASES ANDCONDİTİONS a. Peri-implant Health b. Peri-implant mucositi c. Peri-implantitis d. Peri-implant Soft and Hard Tissue Deficiencies In the revision of the classification; A multidimensional staging and grading system has been established that can be adapted over time as new evidence for periodontitis emerges. Periodontitis in the new classification; -Staging according to the severity of the disease and the complexity of the treatment required Grading according to the presence of additional biological characteristics, progression rate, expected prognosis and risk factors evaluated. In the EFP / AAP 2017 new classification, the terms periodontal and gingival health were also explained, and gingivitis and gingival diseases were examined under 2 main headings: gingivitis induced by dental biofilm and gingival diseases not induced by dental biofilm. This subject will be explained in detail in the "clinical features of gingivitis" course. Briefly; PERİODONTAL HEALTH, GİNGİVAL DİSEASES AND CONDİTİONS Periodontal Health and Gingival Health ● Gingival health not in contact with the periodontium ● Gingival health in reduced periodontal support o Patient with stable periodontitis o Patient without periodontitis Gingivitis:Dental Biofilm-İnduced ● Biofilm-induced gingivitis only ● Gingivitis modified by systemic or local factors ● Drug-induced gingival enlargement Gingival Diseases: Non-Dental Biofilm-Induced ● Genetic / Acquired diseases ● Specific infections ● Inflammatory or immune system diseases ● Reactive processes ● Neoplasms ● Endocrine, nutritional, metabolic diseases ● Traumatic lesions ● Gingival colorations How is Periodontitis Diagnosed? To diagnose periodontitis, 1- Loss of periodontal tissue support due to inflammation (This is the primary feature of periodontitis). 2- Presence of interproximal tissue loss with radiographic evaluations of bone loss - Interdental clinical attachment loss ≥ 2 mm in at least two non-adjacent teeth, or; -More than two teeth should have ≥ 3 mm buccal and lingual pockets and ≥ 3 mm clinical attachment loss. 3- Existing clinical attachment loss is not due to trauma-induced gingival recession 4-No bruise extending to the cervical area 5-No endodontic lesion or vertical root fracture draining from the periodontal space 6- Absence of malposition distal to the second molar 7-The conditions that are not related to the extraction of the third molar tooth should be sought. In other words, the existing tissue destruction must have developed only in relation to inflammatory periodontal disease and not for any other reason. Staging and Grading in Classification of Periodontal Diseases Revising the classification established a multidimensional staging and grading system that could be adapted over time as new evidence for periodontitis emerged. Periodontitis in the new classification; It is divided into stages (staging) according to the severity of the disease and the complexity of the treatment required. Grading was made according to the additional biological characteristics evaluated, progression rate, expected prognosis and presence of risk factors. The primary criterion for the diagnosis of periodontitis is clinical attachment loss in at least two non-adjacent teeth. After excluding periodontitis, which is a symptom of necrotizing periodontitis and systemic diseases, the stage and grade are determined. The staging represents the severity of the disease, includes 4 categories (stages 1-4) and various variables such as clinical attachment loss, amount and percentage of bone loss, probing depth, presence and extent of angular bone defect and furcation involvement, tooth mobility, and tooth loss due to periodontitis. determined after consideration. In staging, stages 1, 2, and 3 are synonymous with mild, moderate, and severe categories of disease.Stage 4 represents the most severe of the disease as vertical bone defects, excessive tooth mobility and need for complex rehabilitation due to tooth loss and other complicating factors may be present. Periodontitis severity The amount of periodontal tissue destruction at the time of diagnosis is one of the most important criteria for the definition of periodontitis. Disease severity; On the one hand, it determines the spread of the disease and on the other hand, the complexity of the treatment required. The number of teeth lost due to periodontitis was included as the determining criterion in the new classification. The primary criterion for the diagnosis of periodontitis is clinical attachment loss in at least two non-adjacent teeth. After excluding periodontitis, which is a symptom of necrotizing periodontitis and systemic diseases, the stage and grade are determined. The rating includes 3 levels (grade A: low risk, grade B: medium risk, grade C: high risk); In addition to periodontitis progression and general health, it covers risky conditions for periodontitis such as smoking, metabolic control level in diabetes. Therefore, grading allows the clinician to include individual patient factors in the diagnosis, which are crucial for comprehensive patient management. In staging, disease severity-damage extent is defined. While determining the stage, the highest value of interdental clinical attachment level, radiographic bone loss and tooth loss are taken as basis. Parameters expressing the complexity of the treatment; furcation involvement, tooth mobility, bone loss pattern. The factors determining the prevalence are <30%, ≥30%, molar/incision involvement. PERİODONTİTİS Necrotizing Periodonal Diseases ● Nekrotizing gingivitis ● Nekrotizing periodontitis ● Nekrotizing Stomatitis Periodontitis Stages: According to the severity and complex of the disease Stage I: Initial periodontitis Stage II: Moderate periodontitis Stage III: Severe periodontitis with tooth loss Stage IV: Advanced periodontitis with loss of dentition • Grades: According to his response to treatment, with a risk of rapid progression Grade I: Slow progressing periodontitis Grade II: Moderately progressive Periodontitis Dereve III: Rapidly progressive Periodontitis Periodontitis as a Manifestation of Systemic Disease Periodontal Abscesses and Endodontic-Periodontal Lesions Parameters determining severity and complexity of treatment in staging; clinical attachment loss, amount and percentage of bone loss, probing depth, presence and extent of angular bone defect and furcation involvement (may shift Stage to a higher stage (eg, class II-III furcation involvement can be shifted to Stage II or Stage III), tooth mobility and tooth loss due to periodontitis. Prevalence: The number and distribution of teeth affected by detectable periodontal destruction is also important for classification. In addition to localized and diffuse options, molar-incisors involvement was also preserved in the new classification. Risk factors: Smoking and diabetes; It has been included in the new classification system because it has been shown in many studies that they are associated with more attachment loss at an earlier age, not getting the expected response after periodontal treatment, and more tooth loss in the maintenance period. To summarize; Staging for periodontitis is based on: - Determining the severity and spread of the disease with detectable tissue destruction indicators - The complexity of the treatment required to meet the functional and aesthetic expectations in the long term Stages of periodontitis (Stage): Stage I: Initial periodontitis: It is the border between gingivitis and periodontitis and represents the early stage of attachment loss. In stage I, the interdental clinical attachment loss is 1-2 mm, and radiographic bone loss (RC) is less than 15% of the root length in the coronal third. And there is no periodontal tooth loss. The probing depth is ≤ 4 mm and the bone loss is usually horizontal. Stage II: Moderate periodontitis: In this stage, the interdental clinical attachment loss is 3-4 mm. Radiographic bone loss is between 15% and 33% of the root length in the coronal third. There is no periodontal tooth loss. The probing depth is ≤ 5 mm and the bone loss is usually horizontal. Stage III: Severe periodontitis (with the potential for additional tooth loss): At this stage, interdental clinical attachment loss is 5 mm or more. Radiographic bone loss is associated with the presence of deep periodontal lesions complicated by the presence of deep intraosseous defects extending to the middle or apical third of the root, furcation involvement (class II or III), a history of tooth loss of periodontal origin (up to 3 teeth), and the presence of localized ridge defects. is characterized. Despite tooth loss, chewing function was preserved. Stage IV: Severe periodontitis (with the potential for dentition loss): At this stage, periodontitis has caused extensive damage to the periodontal support. The resulting damage turns into a loss of chewing function by causing tooth loss. There is a risk of dentition loss if periodontitis is not properly controlled and treated. Interdental clinical attachment loss is more than 8 mm. It is characterized by the presence of periodontal lesions extending to the middle or apical third of the root and multiple tooth loss (≥ 5 teeth) of periodontal origin. The condition is often further complicated by secondary occlusal trauma-induced hypermobility and sequelae of tooth loss. Most often, stabilization and restoration of chewing function are required. Periodontitis stage Stage I (Initial periodontitis) Stage II (Middle periodontitis) Severity Interdental CAL (In the area with the most loss) (CAC) Radiographic bone loss (RK) 1-2 mm 3-4 mm Coronal triple (< 15%) Coronal triple (%15-33) tooth loss No tooth loss due to periodontitis No tooth loss due to periodontitis local features Maximum probing depth (PD) PD ≤ 4 mm Complexity of Treatmentı Usually horizontal bone loss Prevalence For each stage: localized (percentage of teeth affected < 30%) diffuse / molar-incisors involvement For each stage: localized (percentage of teeth affected < 30%) diffuse / molar-incisors involvement Stage III (Advanced periodontitis with potential for additional tooth loss) ≥ 5 mm Stage IV (with potential for advanced periodontitis-dentition loss) extending to the middle or apical third of the root Tooth loss ≤ 4 extending to the middle or apical third of the root Periodontal tooth loss ≥ 5 Maximum probing depth PD ≤ 5mm Usually horizontal bone loss In addition to Stage II: PD ≥ 6mm, Vertical bone loss ≥ 3mm, Furka involvement class II or III, moderate crest defect For each stage: localized (percentage of teeth affected < 30%) diffuse / molar-incisors involvement For each stage: localized (percentage of teeth affected < 30%) diffuse / molar-incisors involvement In addition to stage III: Chewing disorder, Secondary occlusal trauma (≥ 2nd degree mobility), Severe ridge defect, collapse in bite due to posterior tooth loss, slippage of teeth, Less than 20 teeth (10 opposing pairs) For each stage: localized (percentage of teeth affected < 30%) diffuse / molar-incisors involvement ≥ 8 mm The rating for periodontitis is based on: - Expected disease course and risk of progression - Bidirectional relationship between periodontitis and systemic health Grade A: Slowly progressive: At this grade; No evidence of bone loss over 5 years. The radiographic bone loss/age percentage is less than 0.25. The amount of biofilm is high, but the destruction is not much. There are no risk factors such as diabetes and smoking. Grade B: Moderately progressive: At this grade; Radiographic bone loss is less than 2 mm over 5 years. The percentage of radiographic bone loss/age is between 0.25-1. There is a destruction compatible with the amount of biofilm. The patients smoke less than 10 cigarettes per day and the HbA1c value is ≤ 6. Grade C: Fast progressing: At this grade; radiographic bone loss is 2 mm or more over 5 years. The percentage of radiographic bone loss/age is ≥ 1. More destruction is seen than the existing biofilm. The patients smoked ≥ 10 cigarettes per day and the HbA1c value was ≥ 7. Periodontitis degree Primary Criteria Degree modifiers Grade A: Slowly progressive No evidence of bone loss over 5 years Grade B: Moderately progressive < 2mm in more than 5 years Grade C: Fast progressing ≥ 2mm in more than 5 years < 0,25 0,25-1,0 >1 Large deposits of biofilms seen with low degradation Biofilm compatible destruction Direct evidence of progressio n Indirect evidence of progressio n Longitudinal data (clinical attachment loss or radiographic bone loss) % bone loss/age Risk factors Cigarette <10 cigarettes/day More destruction than existing biofilm: Specific clinical patterns suggestive of rapid progression and/or early onset of disease (eg molar-incision pattern, lack of expected response to standard therapy) ≥ 10 cigarettes/day Diabetes HbA1c < 7,0 HbA1c ≥ 7 Phenotype 1) PERİODONTAL MANİFESTATİONS OF SYSTEMİC DİSEASES AND DEVELOPMENTAL AND ACQUİRED CONDİTİONS Systemic Diseases or Conditions Affecting Periodontal Supporting Tissues Mucogingival deformities and Conditions ● Gingival phenotype ● Gingival deficiency ● Frenilum position ● Incompatible color ● Gingival recession ● Shallow vestibul ● Gingival enlargement ● Exposed root surface condition Traumatic occlusal Forces ● Primary occlusal trauma ● Secondary occlusal trauma ● Orthodontic Forces Tooth and Prosthesis-Reated Factors ● Localized factors depending on teeth ● Localized factors due to the prosthesis Periodontal Disease Epidemiology The essence of epidemiology and clinical epidemiology is to relate measures odisease occurrence to suspected causes or interventions. Can the recent dramatic drop in destructive periodontal disease prevalence in the United States be attributed to a change in smoking prevalence? Can the presence of particular microbiologic species around a tooth be related to the risk of future tooth loss? Can the rate of tooth loss in a sample of elderly patients be related to the use of an antimicrobial rinse? With an evidence-based approach, these questions can be most reliably answered by three epidemiologic study designs. Although information about the epidemiology of a disease is based on groups of people, whereas clinicians are primarily interested in the individual patient being treated, thoughtful clinicians understand the value of epidemiologic information for the decisions they must make about the philosophy of their practice and the treatment of each patient. Epidemiology is "the study of the distribution and determinants of health-related states or events in specified population s, and the application of this study to control health problems.As the definition implies, epidemiology ha s three purposes: (1) to determine the amount and distribution of a disease in a population , (2) to investigate causes for the disease, and (3) to apply this knowledge to the control of the disease. The prevalence is the sum of all examined individuals or sites that exhibit the condition or disease of interest divided by the sum of the number of individuals or sites examined. The prevalence can range from 0% (no one has the condition or disease of interest) to 100% (everyone has the condition or disease of interest) Number of the patient Prevalence= The number of people in the population Prevalence, which can be reported as a proportion or percentage, is a measure of the burden of disease in a population. Information about prevalence can be useful for estimating the need for health care resources . For example, prevalence data on dental disease are used for estimating the number of new general dentists and specialists that dental schools should train. Incidence rates—as opposed to the previously introduced measures of disease occurrence—imply an element of time. The denominator in the incidence rate has time as the dimension. Thus, the dimension of incidence rate is 1/time. This dimension is often referred to as “person-time” or “site-time” to distinguish the time summation from ordinary clock-time. The magnitude of the incidence rate can vary between 0 and infinity. When there are no new disease onsets during the study period, the incidence rate is 0. When every person observed dies instantaneously at the start of the study (and thus the sum of the time periods is 0), then the incidence rate is infinity. Incidence, also referred to as risk or cumulative incidence, is the average percentage of unaffected persons who will develop the disease of interest during a given period of time.! Incidence can be viewed as the risk or probability that a person will become a case. It is calculated by dividing the number of new cases of disease by the number of persons in the population who are at risk for the disease. Number of the patient Prevalence= The number of people in the population Randomized Controlled Trials Randomized controlled trials in periodontics typically assign patients or some teeth within a patient randomly to a treatment. Patients are then monitored, and subsequent outcomes are assessed. The randomized controlled trial is the only study design that can provide a probabilistic basis for the making of a causal inference between an intervention and an outcome. Reliable inference regarding the causality of associations can be obtained if the delicate machinery of clinical trial design and analysis is strictly respected. Cohort Studies Cohort studies can also be referred to as exposure-based study designs. Subjects who are free of the disease of interest are classified with respect to an exposure (e.g., cigarette smoking, diabetes) and followed longitudinally for the assessment of periodontal outcomes. Cohorts can be defined by a geographic area, records, exposure status, or a combination of different criteria. Persons within this community were examined in 1959 as part of a community-wide health study. Twenty-eight years later, a subset of these patients was reexamined to study the risk factors for edentulism. Case–Control Studies Case–control studies are typically referred to as outcome-based study designs. Persons with a condition or outcome of interest (i.e., cases) are compared with persons without a condition of interest (i.e., controls) with respect to the history of the suspected causal factors. Many people intuitively think along the lines of a case– control study when evaluating disease causes.For example, if an individual suffers from food poisoning after a party, he or she is likely to compare past food intake with those individuals who did not experience food poisoning. Similarly, if one is diagnosed with a serious illness, a common reaction is to ask, “Why me?” This is usually followed by a comparison of one’s history of exposures with those of other individuals who did not develop the serious illness. The primary goal of a case–control study is to find out what past exposures or factors are different between patients with a disease versus those without the disease. For many conditions, however, a gray area exists between health and disease. Does a patient with a diastolic blood pressure of 90 mm Hg have hypertension? If the tip of a dental explorer "sticks" on the occlusal surface of a molar with no obvious cavitation, is dental caries present? Does a patient with 3 mm of periodontal attachment loss on only one tooth have periodontitis? The consequences of making the wrong decision could be significant.When making diagnoses, clinicians assimilate information from a variety of sources, such as patient interviews, clinical examinations, radiographs, and laboratory data. From this information, the clinician needs to distinguish between normal and abnormal findings . One approach for making this distinction is to consider abnormal as "unusual.In clinical practice, this refers to the unexpected or infrequent finding or test result. What is unexpected or infrequent is sometimes based on statistically defined thresholds, such as two standard deviations from the mean or the 95th percentile (those in the upper 5%). However, thresholds based on statistical considerations are not adequate for all diseases Principles of Diagnostic Testing • Anamnesis • Bleeding on probing • Gingiva • Attachment level • Oral hygiene • Mobility • Radiographies • Occlusal analysis • Biopsy • Laboratory tests In addition to previous limitations radiographs can not provide the desired data for periodontal diagnosis because: They do not show early changes, the knowledge of the past does not respond when asked. It shows the information of the earliest 6 months later. Early recurrence does not occur. Sensitivity and Specificity The sensitivity of a test is the proportion of subjects with the disease who test positive. When a diagnostic test for a disease or condition gives a positive result, the result can be correct (true positive) or incorrect (false positive) When a test gives a negative result, the result can be true (true negative) or false (false negative) The ability of a test to give a correct answer is indicated by its sensitivity and specificity.A highly sensitive test is unlikely to be negative when someone has the disease (false negative) A clinician should choose a highly sensitive test when the consequences of not identifying a person with a disease could be severe , such as during testing for human immunodeficiency virus (HIV) infection.Because sensitive tests rarely give false-negative results, sensitive tests are most informative when the results are negative." That is, if the results are negative, the clinician can be reasonably sure the person does not have the disease. A highly specific test is unlikely to be positive when a person does not have the disease (false positive). Specific tests are especially indicated when the misdiagnosis of disease in the absence of disease could harm a person emotionally, physically, or financially." For example, a false-positive screening test for HIV could cause significant emotional stress until more definitive testing could be performed.Ideally, a diagnostic test would be highly sensitive and specific; however, for most tests, sensitivity comes at the expense of specificity, and vice versa . This is because most diagnostic test results take on values distributed over a range of values. In such cases, a threshold, or cutoff point, must be established to distinguish between positive and negative results . As the threshold is moved higher or lower, the sensitivity and the specificity change in opposite directions. Currently, the threshold for hypertension is a diastolic blood pressure of 90 mm Hg. However, if the threshold for hypertension were increased to 100 mm Hg, the number of false positives would decrease (increased specificity) while the number of false negatives would increase (decreased sensitivity) . The decision of where to place a threshold for a test depends on the penalty for making the wrong decision. If the penalty for a false-negative result is higher than the penalty for a false-positive result, a threshold that makes the test more sensitive should be selected. If the penalty for a false positive result is higher, however, a threshold that makes the test more specific should be selected. Comparison of Diagnostic Test Results with True Disease Status TRUE DISEASE STATUS Test Result Disease No Disease Positive A (True positive) B (False positive) Negative C (False negative) D (True negative) Sensitivity A/(A+C) Specificity D/(B+D) Positive predictive value A/(A+B) Negative predictive value D/(C+D) Sensitivity and specificity are characteristics of a diagnostic test that are useful in choosing an appropriate test. However, once a clinician has received the test result, the most relevant question becomes, "Given this test result, what is the probability that it is right?" The answer to this question is the predictive value of the test. The probability that a person with a positive test has the disease is called the positive predictive value of the test. The probability that a person with a negative test does not have the disease is referred to as the negative predictive value. Consider a population in which no one has the disease. In such a group, all positive results, even for a very specific test, will be false positives. Therefore, as the prevalence of disease in a population approaches zero, the positive predictive value of a test also approaches zero. Conversely, if everyone in a population tested has the disease, all negative results will be false negatives, even for a very sensitive test. As prevalence approaches 100%, negative predictive value approaches zero.« Because of the influence of prevalence on the predictive values of tests, clinicians need to be aware of the patient's probability of having disease.In addition to determining who has a disease at a given point in time, clinicians and epidemiologists are also interested in predicting who will get the disease, The likelihood that a person will get a disease in a specified time period is called risk. For any given disease, the risk of developing the disease differs among individuals. The characteristics of individuals that place them at increased risk for getting a disease are called risk factors . The process of predicting an individual's probability of disease is called risk assessment. Clinicians use risk assessment in several ways. One way is to predict which patients are at risk for disease. For example, people who smoke cigarettes or have diabetes are at a higher risk of developing periodontal disease than nonsmokers or nondiabetic persons. This information may be important for scheduling the frequency of hygiene appointments. Another way clinicians use risk assessment is to aid in the diagnosis of disease. In adolescent patients with localized bone loss on the lower first molars, the detection of significant numbers of Actinobacillus actinomycetemcomitans can help in the diagnosis of early-onset periodontitis. Finally, clinicians often use risk assessment to prevent disease by identifying and modifying risk factors.Prognosis is the prediction of the course or outcome of the disease. Depending on the disease, important outcomes may include death, survival, or quality-of-life issues, such as pain and disability. For periodontal disease, important outcomes include tooth loss, recurrent disease, and loss of function. The characteristics or factors that predict the outcome of a disease once disease is present are known as prognostic factors, and the process of using prognostic factors to predict the course of a disease is called prognosis assessment. GINGIVAL DISEASE An early definition of gingivitis simply stated that gingivitis was inflammation of the gingiva. Another definition in the literature states that gingivitis is inflammation of the gingiva in which the junctional epithelium remains attached to the tooth at its original level." This definition implies that gingivitis does not exist if the tooth has periodontitis. In other words, if the inflammatory process involves the gingiva and the periodontium and loss of periodontal attachment has occurred, then according to this definition, the condition should be called periodontitis, not gingivitis. The presence of plaque-induced gingivitis in a patient with existing but nonprogressing attachment loss has recently been classified. Whether the presence or absence of gingivitis is conditional on the presence of attachment loss has important implications for the estimation of the prevalence of gingivitis.Although the clinical signs of gingivitis are easy to detect, it is not clear how much inflammation a person must have to be considered a gingivitis case. A universally accepted threshold for the amount or severity of gingival inflammation that must be present in an individual does not exist. Gingivitis is measured by gingival indices. Indices are methods for quantifying the amount and severity of diseases or conditions in individuals or populations.Indices are used in clinical practice to assess the gingival status of patients and follow any changes in gingival status over time. Gingival indices are used in epidemiologic studies to compare the prevalence of gingivitis in population groups. In clinical studies, gingival indices are used to test the efficacy of therapeutic agents or devices.All gingival indices measure one or more of the following: gingival color, gingival contour, gingival bleeding, extent of gingival involvement, and gingival crevicular fluid flow. Most indices assign numbers on an ordinal scale (0, 1, 2, 3, and so on) to represent the extent and severity of the gingival condition. Gingival Index: 0 = Normal gingiva 1 = Mild inflammation: Slight change in color, slight edema; no bleeding on probing 2 =Moderate inflammation: Redness, edema and glazing; bleeding on probing 3 = Severe inflammation: Marked redness and edema; ulceration; tendency to spontaneous bleeding The gingival index (GI). Each of the four gingival areas of the tooth (facial, mesial, distal, and lingual) is assessed for inflammation and given a score from 0 to 3 Bleeding is assessed by running a periodontal probe along the soft tissue wall of the gingival crevice. The scores for the four areas of the tooth can be totaled and divided by four to give a tooth score. By adding the tooth scores together and dividing by the number of teeth examined, an individual's GI score can be obtained Gingival Bleeding Index (G.B.L, Ainamo and Bay) Because of the subjective nature of many of the earlier indices, and observations that bleeding is a simple reliable indicator of gingival inflammation, Ainamo and Bay simply used the presence or absence of bleeding on gentle probing as the only criterion for their index. A blunt periodontal probe is passed along the gingival crevice and if bleeding occurs within 10 to 15 seconds, a positive score is given. The number of positive units is divided by the number of gingival margins examined and the result is multiplied by 100 to express the index as a percentage Periodontal Index Russel periodontal index. An individual's score is the sum of the tooth scores divided by the number of teeth examined. The population score is the sum of the individual scores divided by the number of persons examined. Score Criteria 0 Normal. There is neither overt inflammation in the investing tissues nor loss of function due to destruction of supporting tissue 1 Mild gingivitis. There is an overt area of inflammation in the free gingivae which does not circumscribe the tooth 2 Gingivitis. Inflammation completely circumscribes the tooth, but there is no apparent break in the epithelial attachment 6 Gingivitis with pocket formation. The epithelial attachment has been broken and there is a pocket (not merely a deepened gingival crevice due to swelling in the free gingivae). There is no interference with normal masticatory function, the tooth is firm in its socket, and has not drifted 8 Advanced destruction with loss of masticatory function. The tooth may be loose; may have drifted; may sound dull on percussion with a metallic instrument; may be depressible in its socket INDICES EVALUATING PLATE DEPOSIT Orginally the oral hgygine index inducluded a measurement of twelve tooth surface, subssequently reduced to siz tooth surfeces, it is now known as the simplfed oral hygne index . The amount measured in the OHI-S are on the labial surfaces of teeth number 11,16,26,31 and the lingual surfaces of 36 and 46. The index composed of two component, one describing the soft and one the calcified deposits present OHI-S Oral Hgygine İndex (Green-vermillion 0- No debris or stain present. 1- Soft debris covering not more than one-third of the tooth surface being examined or the presence of extrinsic stains without debris regardless of surface ares coverd 2-Soft debris covering more than one-third but not more than two-third of the exposed tooth surface 3-Soft debris covering more than two-thirds of exposed tooth surface OHI-S Oral Hgygine İndex Oral calculus index(CI-S) 0- No calculus present. 1- Supragingival calculus covering not more than 1/3 of the tooth surface being examined. 2-Supragingival calculus covering more than 2/3 of the exposed tooth surface or teh presence of individual flecks of subgingival calculus around the cervical portion of the tooth. 3-Subragingival calculus covering more than 2/3 of exposed tooth surface or a continuous heavy bank of subgingival calculus around the cervical portion of the tooth PI Plak İndex (Löe, Silness) 0- No plaque in the gingival area 1- A film of plaque adhering to the free gingival margin and adjacent area of the tooth. The plaque may only be recognized by running a probe across the tooth surface, not visible by the naked eye. 2- Moderate accumulation of soft deposits within the gingival pocket, on the gingival margin and-or adjacent tooth surface,which can be seen by the naked eye 3- Abudance of soft matter within the gingival pocket and/or on the gingival margin and adjacent tooth surface 1-Newman M, Takei H, Klokkevold P, Carranza F. Newman and Carranza (2019); Clinical Periodontology, 13th Ed., Elsevier.