# Community Dental Health - PowerPoint PPT Presentation

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Community Dental Health. Final Review. Errors. Type I (Alpha): Is made when we reject the null hypothesis when, in fact, it is true, therefore could lead to practicing worthless treatments that do not work. Type II (Beta):

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Community Dental Health

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## Community Dental Health

Final Review

### Errors

Type I (Alpha):

• Is made when we reject the null hypothesis when, in fact, it is true, therefore could lead to practicing worthless treatments that do not work.

Type II (Beta):

• Is made when we do not reject the null hypothesis when, in fact, it is false, therefore could lead to overlooking a promising treatment.

e.g.: the law – “innocent” or “guilty”

### Statistical Significance

Two Groups Research Designs

Student’s “t” test for statistical significance:

• Compares the means of 2 groups to determine if difference between them is real or a result of sampling fluctuation under conditions of ho (no difference)

• Best if applied to results where 2 groups received different experimental treatments

• Used when population standard deviation is not known

### Statistical Significance

Multiple Groups Research Design:

• Analyses of Variance Test for Statistical Significance = ANOVA – f value

• The test to determine whether differences in multiple group scores have occurred by chance (sample fluctuation) or by applied experimental manipulation

### Statistical Significance

ANOVA compares the variability in 2 ways:

1. Between Group Variance (BGV):

• Referred to as treatment effect

• Reflects the magnitude of the difference among the group means

• Number of d.f. for BGV is calculated by the formula K – 1 where K stands for the number of groups

### Statistical Significance

2. Within Group Variance (WGV):

• Referred to as residual effect

• Pooled variance of all the groups in the design added together

• This variance represents the uncontrolled, unexplained variance due to the chance effect

### Statistical Significance

Chi-square test:

• Compares observed and expected frequencies not means

• Best used with discrete variables where subjects can be assigned to mutually exclusive groups

E.G.: Males, females, smoking, non-smoking

• Based on the normal curve and degree of freedom

• Chi-square value calculated and compared with pre-set critical value before accepting / rejecting Ho.

### Correlation

• Refers to the linear relationship between two variables

• Statistical measure for determining the strength of the linear relationship

• Based on the number of variables, nature of variables (discrete or continuous) and the scale of measurement. (nominal, ordinal, interval and ratio)

### Correlation Analyses

Used to determine the relationship between variables each of which can be measured for each individual in the sample

e.g.: - height and weight

- profit and loss

### Correlation Analyses

The analysis yields a measure called: Correlation Coefficient known as Pearson’s r.

• Measures the direction and strength of the relationship of the two variables to produce the numerical correlation ranging from –1.0 to +1.0

### Variables

The items of a study that are measured.

Independent variable(s) (intervention):

• All the factors that influence the characteristics which are under investigation

• Some of the independent variables will be manipulated as part of the study or experiment = “controlled”

I.E.: Age, gender, type of oral hygiene aid, amount of drug administered

### Variables

Independent variable(s) (intervention):

“Uncontrolled” variables can not be manipulated:

• Subject’s prior experience

• Subject’s knowledge base

• Subject’s emotional state

• Subject’s values, beliefs

I.E.: Dental hygienist evaluating tooth brushing method for children = “controlled variable”

### Variables

Dependant variable(s)

• The measurable result or outcome which the researcher hopes will change or not change as a result of the intervention

• Their values are determined by all of the independent variables operational at the time of the study (both controlled and uncontrolled)

N.B.: Called dependant because result depends on independent variable

E.G.: Subject’s plaque scores / gingival condition

(Measured before and after)

Result depends on method used.

### Four Types Of Scales

1.Ordinal Scale:

Discrete categories are ranked in increasing or decreasing order.

E.G.: Grades: A, B, C … letters

Conditions: worse, fair, good

State: no treatment needed, treatment needed, urgent treatment needed

- No comparison can be made between categories.

### Four Types Of Scales

2. Nominal scale:

Discrete categories are named or labeled for identification purpose.

E.G.: Green, tall, defective, yes/no, voting list

• No quantitative relationship to each other

• Weakest scale

### Four Types Of Scales

3. Interval Scale:

Data conforms to a measurement scale with fixed units. No absolute zero point. Differences between points can be measured.

E.G.: Thermometers (0 is a temperature).

4. Ratio Scale:

Data conforms to a measurement scale with fixed units with an absolute zero point. Differences between points is the same.

E.G.: Weight scale, age (birth to 5 years), exams (0 to 100 marks).

### Epidemiology

• The study of the amount, causes, distribution and controls of diseases and health conditions among given populations.

• It attempts to determine which associated factors are important for prevention and control

### The Uses of the Science of Epidemiology

1.Description of normal biologic processes

Examples: stages of growth, blood groups, and times and order of tooth eruption.

2. Understanding the natural history of diseases.

Observations of disease progression and outcome in populations have enabled investigators to distinguish those diseases that are fatal or disabling from those that will resolve uneventfully.

### The Uses of the Science of Epidemiology

3.Distribution of disease in the population.

By age, gender, race, geographic region, and socioeconomic status. Demonstrates trends in disease prevalence and distribution. (Study of patterns among groups).

4.Studying non-disease entities.

Suicide, injury.

### The Uses of the Science of Epidemiology

5.Identifying the determinants of disease.

Specific study designs can identify the risk factors and risk indicators associated with a disease and can lead to intervention strategies for prevention and control.

6.Testing hypotheses for disease prevention and control.

Dental example: the various uses of fluorides to reduce caries incidence.

### The Uses of the Science of Epidemiology

7.Planning and evaluating health care services.

Data can be used to assist planning decisions on services and types of personnel required. Validates the effectiveness of treatment techniques and quality of treatment provided.

### Epidemiologic Studies/Research

Descriptive, Experimental, Analytic

Every study/research, no matter how modest, needs a Protocol.

• A written plan containing the purpose and detailed operation of the study

• Helps it’s design

• Helps researchers to anticipate potential problems

• Helps in writing final report because the protocol forms the basis of the report

n.b.: essential for research with humans

### Descriptive Epidemiology

• “What” is the disease or health outcome under study?

• “Who” is getting the disease? (Young, old, male, female)

• “Where” is the disease occurring? (In Canada, urban / rural areas)

• “When” is the disease occurring? (During tooth formation, all the time)

### Descriptive Epidemiology

• Incorporates incidence, prevalence, rates.

• “States a case definition” which:

• Generates a hypothesis to be further tested regarding causation and prevention.

• Involves – description, documentation, analysis, and interpretation of data to evaluate a current event or situation.

• Surveys, questionnaires, indexes.

• No interventions done.

### Analytic Research (Correlational)

• Studies/surveys in which data collection and analysis are designed to answer a particular question

• Seek out cause and effect

E.G.: Clinical trial to test reduction of caries by weekly fluoride mouth rinse

### Study Designs (Hypothesis – Testing)

• Cross sectional: study of a condition in a group at one point in time (non-experimental)

• Longitudinal: study of a condition in a group two or more times

• Retrospective: (historical) study the outcome of interest and then probe back for exposure information

• Prospective: study information on exposure of interest and compare eventual outcomes

### Experimental Research

• Used when cause of disease is established and researcher wants to study the effect of an intervention or experiment in relation to that disease

E.G.: A new drug treatment or sealants for 7-12 year olds

Dental Programs – Federal Government:

• In hospital surgical – dental procedures

• Cleft Lip and Palate Program

• Ontario Works Program (block funding to provinces)

• Adults – Emergency treatment only

• Children to Age 18 – more comprehensive

• Separate Dental Coverage: (3 populations)

• Armed Forces, War Veterans and R.C.M.P.

• Inmates of federal correction institutions

• Native Indian and Inuit persons (MSB)

Provincial Government

(Ontario Ministry of Health)

• 41 health units in Ontario

• Develops and publishes Mandatory Core Programs

• Funds provision of programs

School Dental Health Services

Dental Indices Survey (DIS):

• Annual surveillance program of all 5–14 yr. old students

Children In Need of Treatment (CINOT):

• School screening referral and follow-ups

• Clinical preventive services

• Family oral health education

Dental Health Education

(Dental Health Programs Resource Officer):

• Provides training and resources for targeted groups

• Multiple strategies approach

Municipal Government Public Health Services

• Through the Board of Health (Regional Health Committee)

• Organizes broad-based public health services in response to local needs

• Environmental services

• School health services

• Preventive programs

• Delivers Mandatory Core Programs

• Dental programs – CINOT and DIS

• Funds service providers

• Dr.’s, PHN’s, DH’s and nutritionists

• Support staff

To provide:

• Up-to-date scientifically sound information

• The “best” client care in role of clinician, educator, manager,advocator and researcher

• Cost-effective practices

To understand:

• Consumer perspectives / involvement

• New technologies

n.b.: professional development standards require practice to be research or evidence-based when possible

### My Expectations

Students will:

• Appreciate and understand what Community Dental Health involves

• Attend classes regularly and participate in discussions

• Will communicate openly if there are problems and provide feedback

• All attain high passing grades