Epi ni maam formantes :)


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Epi ni maam formantes :)

  1. 1. EPIDEMIOLOGY- Study of the distribution of a disease or a physiologic condition in human populationsand of the factors that influence this distribution- 3 components included: 1. population – groups of people defined either by geographic boundaries or characteristics or attributes 2. Distribution – occurrence of a disease or condition in groups of people 3. Factors – causes responsible for the observed distribution- Aims: 1. prevention of disease 2. maintenance of health- Scope: - studies of infectious diseases, chronic diseases, accidents, drug abuse, suicide, injuries and health services research - epidemic and inter-epidemic periods with sporadic and endemic occurrence of diseases- Uses: 1. can identify and measure the importance of health problems, describe the high risk groups and elucidate the cause of these problems 2. for understanding the natural history of disease 3. is essential for disease surveillance and control 4. contributes to the planning, monitoring and evaluation of health services 5. serves as a key instrument in the formulation of health policies which may incorporate social, behavioral and economic dimensions in addition to the provision of health servicesEPIDEMIOLOGIC REASONINGA. Descriptive studies - begins with observations made in the course of clinical practice or examination of disease patterns - arouses suspicion concerning the possible effects of a particular factor on diseases occurrence - observations are utilized in descriptive studies that lead to formulation of specific hypothesisB. Model-building and formulation of hypothesis - factor or factors being considered to be potentially playing significant role/s in the observations are associated to the disease occurrence, patterns and distributionC. Analytic Studies - studies of individuals designed to include an appropriate control group and whose aim is to determine if a statistical association exists between a given factor and a particular outcomeD. Analysis of Results - the observed statistical association can be considered to represent a causal relationship between exposure (factor) and outcome on the basis of the following criteria:
  2. 2. 1. strength of the association 2. consistency of findings from other studies 3. temporal sequence between exposure and outcome 4. biologic plausibilityEPIDEMIOLOGIC APPROACH- Consist of procedures of scientific inquiry to describe the distribution and elucidate theetiology of disease in a population- Begins by reviewing the literature for available knowledge regarding the problem ofinterest- There’s discovery of what is already known about the problem and knowledge gaps areidentified- Knowledge gaps are considered in the formulation of hypothesis- Hypothesis is tested using epidemiologic study designs- Conclusions are drawn based on the analysis of results- Study Designs1. Observational – examination of the natural course of events to simply document whohave/do not have the disease and who is exposed or unexposed to risk actors a. Descriptive - characterize disease occurrence in a population; do not attempt to analyze links between exposure (factor) and effects (disease) a.1. Case study - medical occurrences in a single patient and can represent first clues in the identification of new disease or adverse effects of exposures a.2. Case Series - collection of individual case reports that may occur within short period of time a.3. Ecologic studies - considers patterns of disease among populations by comparing disease rates in different geographic regions - first step in investigating a possible exposure-disease relationship - also called correlation study EX. Cancer rates in communities with different patterns of MSG consumption a.4. Cross-sectional - measures exposure and disease status at the same time among individuals in a well-defined population (“What is happening?”) - can not determine whether exposure preceded or resulted from the disease - also called prevalence study EX. Occurrence of periodontitis among NIDDM (non-insulin dependent diabetes mellitus) patients b. Analytical – investigate and evaluate relationships between health status and other variables b.1. Cohort study - compares the occurrence of an exposure between cases (those who have the disease) and controls (those who do not have the disease) (“What will happen?”) - a group of people (cohort) are classified according to exposure (w/ or w/out) and subsequently followed up to compare the outcome between the groups - also called follow-up study or incidence study
  3. 3. EX. Relation between fluoride intake and fluorosis b.2. Case-control - compares the occurrence of outcome between those exposed and not exposed to specified risk factors (“What happened?”) EX. Relation between thalidomide and unusual limb defects in babies born in 1959 and 1960 b.3. Cross-sectional2. Experimental – examination of outcomes in which there is control of the conditionsunder which the study is conducted and of the assignment of subjects to either thetreatment or comparison group a. Randomized controlled trials or Clinical trials - subjects with equivalent characteristics are randomly allocated to treatment and control groups, and the results are assessed by comparing the outcome EX. The effect of sugar-free gum-chewing in reducing incremental dental caries among 6 – 12 years old b. Field trials - studies involving disease-free populations but presumed to be at risk (ex. field trial of Salk vaccine to prevent polio among children) - evaluate interventions aimed at reducing exposure like the elimination of lead paints in home environment (ex. to prevent the risk of lead poisoning) c. Community trials or community intervention studies - treatment groups are communities rather than individuals; for diseases that have their origins in social conditions which can be more effectively influenced by interventions directed at group behaviorMEASURES OF ORAL DISEASE OCCURRENCE A. Dental Caries 1. DMFT - describes the amount (prevalence) of dental caries in an individual and is obtained by calculating the number of Decayed (D), Missing (M) and Filled (F) teeth - either calculated for 28 permanent teeth, excluding 3rd molars or for 32 teeth - frequently employed in descriptive studies describing the prevalence of dental disease - sum of the three figures forms the DMFT-value (Ex: DMFT of 4-3-9=16 means that 4 teeth are decayed, 3 teeth are missing and 9 teeth have fillings) a. D/DMFT - measure of the lack of dental treatment for the individual or community of individuals b. M/DMFT - represents predominantly the end result of a caries in contrast to another population group which does not have many missing teeth c. F/DMFT - indicates the amount of dental treatment rendered to an individual or to a population groupTo present caries data for adults, the following designations are used:a. DMFT Rate: Mean number of decayed, missing & filled teeth of population examinedb. %DMFT: Percentage of population affected with dental cariesc. MT: Mean number of missing teethd. %D: Percentage with untreated decayed teeth
  4. 4. e. MNT: Mean number of teethf. DT: Mean number of decayed teethg. %Ed: Percentage edentulous2. DMFS – detailed index of DMF calculated per tooth surface - Molars and premolars are considered having 5 surfaces, front teeth 4 surfaces - Maximum value for DMFS comes to 128 for 28 teeth - employed in therapeutic investigations or trials because it focuses upon the incidence of disease (Ex. DMFS of 22-3-19=44 means that 22 surfaces are decayed, 3 teeth are missing and 9 surfaces have fillings)* For the primary dentition, consisting of maximum 20 teeth, the correspondingdesignations are "deft" or "defs", where "e" indicates "extracted and not exfoliated tooth".B. Periodontal Disease Indices 1. Community Periodontal Index - formerly called Community Periodontal Index for Treatment Needs - measure of the periodontal health - uses 3 indicators of periodontal status: a. presence or absence of gingival bleeding b. supra- or subgingival calculus c. periodontal pockets-subdivided into shallow (4-5mrn) and deep (6mm or more C. Oral Hygiene 1. OHI-S (Oral Hygiene Index-Simplified) - has two components, the Debris Index and the Calculus Index - based on numerical determinations representing the amount of debris or calculus found on the pre-selected 6 tooth surfaces: four posterior (buccal & lingual) and two anterior (labial) teeth Debris Index = bu-scores + li-scores / Total number of examined surfaces Calculus Index = bu-scores + li-scores / Total number of examined surfaces OHI-S index = Debris Index + Calculus Index Criteria for classifying debris Scores Criteria 0 No debris or stain present 1 Soft debris covering not more than one third of the tooth surface, or presence of extrinsic stains without other debris regardless of surface area covered 2 Soft debris covering more than one third, but not more than two thirds, of the exposed tooth surface. 3 Soft debris covering more than two thirds of the exposed tooth
  5. 5. surface. Criteria for classifying calculusScores Criteria 0 No calculus present 1 Supragingival calculus covering not more than third of the exposed tooth surface. 2 Supragingival calculus covering more than one third but not more than two thirds of the exposed tooth surface or the presence of individual flecks of subgingival calculus around the cervical portion of the tooth or both. 3 Supragingival calculus covering more than two third of the exposed tooth surface or a continuos heavy band of subgingival calculus around the cervical portion of the tooth or both. Right molar Anterior Left molar Total Bu Li La Li Bu Li Bu Li Max 3 - 2 - 3 - 8 - Man - 2 - - 1 2 1 4Debris Index = bu-scores + li-scores / Total number of examined surfaces Debris Index = (9+4) / 6 = 2.2 Right molar Anterior Left molar Total Bu Li La La Bu Lil Bu Li Max 1 - 0 - 1 - 2 - Man - 1 - 2 - 2 2 3 Calculus Index = bu-scores + li-scores / Total number of examined surfaces) Calculus Index = (4+3) / 6= 1.2 OHI-S index = 2.2 + 1.2 = 3.4 2. Silness-Löe plaque index - recording both soft debris and mineralized deposits on 16, 12, 24, 36, 32, 44 (Missing teeth are not substituted) - Each of the four surfaces of the teeth (bu, li, me & di) is given a score from 0-3 & the scores are added and divided by four to give the plaque index for the tooth
  6. 6. - The index for the patient is obtained by summing the indices for all six teeth and dividing by sixScores Criteria0 No plaque A film of plaque adhering to the free gingival margin and adjacent area of the tooth. The plaque may be seen in situ only1 after application of disclosing solution or by using the probe on the tooth surface. Moderate accumulation of soft deposits within the gingival2 pocket, or the tooth and gingival margin which can be seen with the naked eye. Abundance of soft matter within the gingival pocket and/or on3 the tooth and gingival margin. Assuming a tooth (16) with the following scores on the four surfaces: Surface Scores Buccal 2 Plaque Index = (2+1+1+2) / 4 = 1.5, Lingual 1 plaque index for the tooth is moderate accumulation of soft deposit within the Mesial 1 gingival pocket, or the tooth and gingival Distal 2 margin which can be seen with the naked eye Tooth Index The index for the patient is obtained by summing the indices for all six teeth and 16 1.5 dividing by six 12 1.3 24 1.2 36 1.0 The index for patient is 32 1.6 44 1.3 = (1.5 + 1.3 +1.2 + 1 + 1.6 + 1.3) / 6 = 1.4Fluorosis - lesions are usually bilaterally symmetrical and tend to show a horizontal striated pattern across the tooth - premolars and second molars are most frequently affected, followed by the upper incisors ; mandibular incisors are least affected D. Fluorosis Index
  7. 7. - recording is made on the basis of the two teeth that are most affected - if the two teeth are not equally affected, the score for the less affected of the two should be recorded - when teeth are scored, examiner should start at the higher end of the index, i.e. "severe", and eliminate each score until he or she arrives at the condition present - if there is any doubt, the lower score should be givenCODE and CRITERIA The enamel surface is smooth, glossy and usually a pale0 Normal creamy-white colour. The enamel shows slight aberrations from the translucency of1 Questionable normal enamel, which may range from a few white flecks to occasional spots. Small, opaque, paper-white areas scattered irregularly over2 Very mild the tooth but involving less than 25% of the labial tooth surface. The white opacity of the enamel of the teeth is more extensive3 Mild than for code 2, but covers less than 50% of the tooth surface. The enamel surfaces of the teeth show marked wear and4 Moderate brown stain is frequently a disfiguring feature. The enamel surfaces are badly affected and hypoplasia is so marked that the general form of the tooth may be affected.5 Severe There are pitted or worn areas and brown stains are widespread; the teeth often have a corroded appearance. Excluded8 (e.g. a crowned - tooth)9 Not recorded - NATURAL HISTORY OF DISEASE • Process by which disease occur and progress in the human host • Involves 3 factors: 1.causative agent - Factor whose presence or absence causes a diseases a. physical - mechanical forces or friction that may produce injury - atmospheric conditions like extremes of temperature and excessive radiation b. chemical - those that affect human physiology through chemical actions - include substances that may occur as dusts, gases, vapors, fumes or liquids c. nutrient - refer specifically to basic components of the diet d. biological - all living organisms like insects, worms, protozoa, fungi and bacteria; also viruses
  8. 8. e. genetic - those transmitted from parent to child through the genes f. psychological agents - stressful social circumstances in the environment that affect physiology by psychosomatic means Characteristics of Agents 1. Infectious agents a. infectivity – extent to which agent is able to cause infection b. pathogenicity – ability of agent to cause a disease c. virulence – power of agent to disable the host 2. Non-infectious agents a. concentration and toxicity for chemical agents b. size, shape and intensity for physical agents c. chronicity or suddenness for psychological agents d. homo- or heterozygocity of genetic material for genetic agents 2. susceptible host - Individual human in whom an agent produces disease when susceptible due to lack of immunity or inherent resistance 3. environment - All external conditions and influences affecting the life of living things - Provide reservoirs where agents can reside &/or reproduce, and modes of transmission for transporting agents from reservoir to a host Categories: 1. Physical - geological structure of an area and the availability of resources like water and flora, that influence the number and variety of animal reservoirs and certain insects that function as vectors to carry an agent from reservoir to host - influenced by weather, climate and season 2. Socio-economic - relates to the social norms & economic status of an area - influences infectious agents present as to extent of environmental sanitation practices or the availability of medical facilities and services - influences non-infectious agents as to extent of psychological stressors, means of livelihood or place of residence 3. Biological - living plants and animal that may serve as either: a. reservoir – environment in which infectious agents normally live and multiply, are dependent for survival and reproduction b. vector – living carrier that transports infectious agents from infected individuals, or their wastes to susceptible individuals, their food or immediate surroundings• The Disease Process 1. Pre – pathogenesis a. susceptibility - disease has not yet developed but the groundwork has been laid through presence of risk factors that favor its occurrence b. adaptation - disease may/not develop when exposed to agent at this time depending on the ability of host cells or functional systems to accommodate the agent 2. Pathogenesis
  9. 9. a. Early pathogenesis - no symptoms to indicate presence of disease but pathogenic changes have begun - changes may be detectable by sophisticated laboratory tests to confirm disease b. clinical disease - symptoms experienced by patient and signs apparent to clinician on physical examination b.1.early clinical stage – when clinical diagnosis can be made b.2.. late clinical stage – when disease becomes severe - patient may recover, suffer from residual defect or die • Infectious 1. incubation period - relatively very short 2. short duration of illness 3. host generally recovers without any residual disability or need for long-term therapy • Non-infectious 1. latency period- relatively long 2. long duration of illness 3. host generally does not recover; with residual disability and requires long- term therapyMode of Transmission1. Direct contact such as sexual contact, animal bites, respiratory droplets - air-borne, blood-borne2. Indirect contact (via vehicles) - fomites (mucus droplet, utensils) - vector like arthropods a. mechanical transmission b. biological transmission - food and waterPortal of entry and exit a. respiratory tract - air-borne b. digestive tract - food- and water-borne c. genito-urinary tract - fluid-borne via parenteral route d. skin and mucous membranes - blood-borne via parenteral route - vector-bornePrevention and Control of Disease- Directed towards:1. source or reservoir of infection or agent a. Isolation – separation for the period of communicability of carriers from others to prevent transmission of agents to susceptibles
  10. 10. b. Quarantine – limitation of freedom of movement of persons exposed to a communicable disease (contacts) for a period of time not longer than the longest usual incubation period of the disease c. Cleaning – removal of infectious/non-infectious agents and organic matters by washing or scrubbing surfaces or areas which favor survival and replication of agents d. Disinfection – killing of infectious agents on inanimate objects by chemical or physical means e. Treatment – use of antimicrobials to shorten the course of illness and period of communicability For non-infectious a. Removal of actual agent from environment before contact with susceptible b. Minimize amount of agent2. agent or mode of transmission a. Disinfestation – physical or chemical process that destroys or removes small animal forms like arthropods on persons, clothing or environment a. fumigation b. insecticide c. rodenticide b. Provision of safe and adequate water c. Proper sewage and waste disposal d. Food sanitation and milk hygiene e. Proper housing drainage3. susceptible population a. Health education – process by which individuals/groups of people learn to promote, maintain or restore health b. Personal hygiene – measures primarily within the individual’s responsibility which promote health and limit the spread of diseases c. Chemoprophylaxis – administration of chemicals like antibiotics to prevent development of infection or its progression to actively manifest disease d. Repellent – chemical applied to skin/clothing/areas to discourage arthropods from alighting & attacking/penetrating persons e. Immunization* For non-infectious a. Personal protective equipment b. Biologic monitoring c. Screening