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EPIDEMIOLOGY

EPIDEMIOLOGY. Is defined as the study of health and disease in populations and of how these states are influenced by hereditary, biology, physical environment, social environment and ways of living. TYPES OF EPIDEMIOLOGICAL STUDIES.

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EPIDEMIOLOGY

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  1. EPIDEMIOLOGY Is defined as the study of health and disease in populations and of how these states are influenced by hereditary, biology, physical environment, social environment and ways of living.

  2. TYPES OF EPIDEMIOLOGICAL STUDIES • DESCRIPTIVE STUDIES (observational epi). Surveys records the prevalence of various conditions “meaning” The word prevalence serve to indicate per age group, the proportion of the population affected, with a given degree of severity of periodontal disease, as their highest score, and is given in percent of the population examined. (Age, sex, and geographic location).

  3. ANALYTICAL STUDIES: Attempts to determine associations between disease and possible risk factors determinants, and quantify the degree of risk. RISK: Is the probability that a specified event will occur e.g. that an individual will become ill or die within a stated period of time or particular age. Then trying to remove or modify the risk factor e.g. smoking, sugar, etc…

  4. Analytical studies, frequently require at least TWO sets of measurements among the same people at different times to determine the progress of the condition. • INCIDENCE STUDIES: It is defined as the change in prevalence of a condition over a given period of time. In another word, it is the rate at which new cases of the disease appear in a population.

  5. CROSS-SECTIONAL STUDIES: A comparison of the prevalence of dental caries in TODAYS sixth-grades with that of ten years ago, must be cross-sectional study, though it is obvious that different persons are studied each time. • LONGITUDINAL STUDIES: If all the children originally in first grade in a school system are studied periodically until they finish sixth grade, the study would be longitudinal because same children would be seen on several occasions.

  6. EXPERIMENTAL STUDIES:“Clinical trials”. Is a controlled study of group comparison based on epidemiological principles and designs to test the hypothesis that a particular agent or procedure favorably alters the natural history of a disease. The group receiving the agent is the test group, and the comparable group not subjected to the agent is the control group. (Age, sex, race and socioeconomic status are similar, and most importantly Disease Experience).

  7. INDICES USED TO EVALUATE SIGNS, SYPTOMS AND ETIOLOGICAL FACTORS ASSOCIATED WITH THE DISEASE OF THE PERIODONTIUM.

  8. Definition of an Index: As defined by Russell 1966. Is a numerical value describing the relative status of a population on a graduated scale with definite upper and lower limits, which is designed to permit and facilitate comparisons with other populations classified by the same criteria and methods.

  9. Ideally an Index, including its scoring criteria should posses the following properties: • Clarity, Simplicity and Objectivity. The examiner should be able to memorize the criteria, and the Index should be reasonably easy to apply so as not to lose time in field examination. • Acceptability. The use of an Index should not be painful or demeaning to the subject.

  10. Validity. The Index must measure what it is intended to measure, it should correspond with clinical stages of the disease under study at each point (reflects the true disease situation). • Quantifiability. Should be amenable to statistical analysis. So as the status of a group can be expressed by a distribution, MEAN and MEDIAN, or other statistical measures.

  11. Reliability. The Index should be able to measure consistently at different times and under variety of conditions (Reproducibility). • Inter-examiner-variability. • Intra-examiner-variability. • Sensitivity. The Index should be able to detect reasonably small shifts in either direction.

  12. Classification and Characteristics:

  13. INDICES TO MEASURE GINGIVITIS Gingival Index: “Loe and Silness 1963” • The first index to evaluate every single tooth surface. • A blunt probe “Instrument is usually used”. • Gingival tissue is divided into four scoring units.

  14. Buccal – Mesial – Lingual and Distal. • Scores from 0 – 3. • GI for single surface. • GI for a tooth “4 surface”Total = GI tooth. 4 • GI for individuals =Total GI/per tooth Number of teeth • Can be used for a group of teeth GI for e.g. 6 teeth.

  15. Converting numerical scores into subjective or varying degrees of clinical gingivitis as follows: Gingival ScoresCondition 0.1 – 1.0 Mild Gingivitis 1.1 – 2.0 Moderate Gingivitis 2.1 – 3.0 Severe Gingivitis

  16. Criteria for 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 and tendency to spontaneous bleeding. • This Index can be used also as simplified form. 6 2 4 4 2 6

  17. INDICES TO MEASURE PLAQUE Plaque Indices: “Silness and Loe 1964” • Epidemiological studies: It provides a quick and representative picture of the level of oral hygiene in a population. • In private practice: Is not intended to determine the average plaque accumulation but to record the distribution of plaque in the oral cavity i.e. to determine the “Plaque Picture” of an individual patient.

  18. Some areas of the patient’s dentition may be cleaned quite effectively, while others e.g. the lingual surfaces of mandibular molars remain routinely uncleaned. • The most important consideration in the plaque index is the thickness of plaque along the gingival margin. • It involves the same scoring units of the tooth of the Gingival Index. “Loe and Silness 1963”.

  19. A mouth mirror and dental explorer are used. • To visualize plaque, it is important that compressed air be used to dry the tooth surfaces prior to the evaluation of the unstained plaque deposits. PLAQUE IS NOT STAINED. • It does not exclude or substitute for teeth with gingival restorations, or crowns, or “missing teeth” if partial scoring is used.

  20. PERIODONTAL SCREENING AND RECORDING Index

  21. Principles of the P.S.R. In this system, the dentition is divided into six sextants: Premolars & Molars Canines & Incisors Premolars & Molars R. Ant. L. Premolars & Molars Canines & Incisors Premolars & Molars

  22. THE PROBE • The tip is 0.5 mm spherical ball. • Calibration of its use. • Force 20-25 grams. • Path of insertion.

  23. Prepared by: Dr. Nicola Barghout

  24. P.S.R. CODING 0 – The black band remains fully visible. 1 – As code 0 – except bleeding on probing. 2 – As code 1 – except the probe detects supra and subgingival calculus, overhangs. 3 – The black band disappears partly into the gingival crevice. 4 – The black band disappears into the gingival crevice.

  25. P.S.R. SCORING EXAMPLE

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