Oral Epidemiology: A Textbook on Oral Health Conditions, Research Topics and Methods

Foreword
Foreword
Contents
About the Editors
Editors and Contributors
Contributors
I: Oral Health Diseases and Disorders
1: The Contribution of Epidemiology to Oral Health Research
	1.1	 Introduction
	1.2	 Association and Causality
	1.3	 Measures of Disease Frequency
	1.4	 Typology of Designs for Epidemiological Studies
	1.5	 Measures of Association
	1.6	 Observational Studies
		1.6.1	 Case Reports or Case Series
		1.6.2	 Ecological Studies
		1.6.3	 Time Series Studies
		1.6.4	 Cross-Sectional Studies
		1.6.5	 Case-Control Studies
		1.6.6	 Cohort Studies
	1.7	 Interventional (Experimental) Studies
		1.7.1	 Clinical Trials
		1.7.2	 Community Intervention
	1.8	 Internal and External Validities
	1.9	 Sources of Error in Epidemiological Studies
	1.10 Final Remarks
	References
		Further Reading
2: Global Burden of Oral Conditions
	2.1	 Introduction
	2.2	 Global and National Burden of Oral Conditions Combined
		2.2.1	 Untreated Dental Caries
			2.2.1.1	 Burden of Untreated Dental Caries
		2.2.2	 Severe Periodontitis
			2.2.2.1	 Burden of Severe Periodontitis
		2.2.3	 Total Tooth Loss
			2.2.3.1	 The Burden of Total Tooth Loss
	2.3	 Conclusion
	References
		Further Reading
3: Dental Caries
	3.1	 Introduction
	3.2	 Measuring Dental Caries
		3.2.1	 Indices and Instruments
			3.2.1.1	 The DMF Index
			3.2.1.2	 Dental Care Index
			3.2.1.3	 International Caries Detection and Assessment System: ICDAS Index
			3.2.1.4	 Pulpal Involvement, Ulceration, Fistula, and Abscess: PUFA Index
			3.2.1.5	 Caries Assessment Spectrum, and Treatment: CAST Index
			3.2.1.6	 The British Association for the Study of Community Dentistry: BASCD
			3.2.1.7	 Australian Research Centre for Population Oral Health, Australia: ARCPOH
			3.2.1.8	 National Health and Nutrition Examination Survey: NHANES
		3.2.2	 Criteria for Assessing Dental Caries
		3.2.3	 Root Caries
	3.3	 Analysing and Reporting Dental Caries
	3.4	 Burden of Disease
	References
		Further Reading
4: Epidemiology of Periodontal Diseases
	4.1 Introduction
	4.2 What Do We Understand by ‘Periodontal Diseases’?
	4.3 Periodontal Disease: Gingivitis and Periodontitis
	4.4 Measuring and Recording Gingivitis and Periodontitis
		4.4.1	 Signs and Symptoms of Gingivitis and Periodontitis
	4.5 Describing the Results of Periodontal Epidemiological Studies
	4.6 Reporting Standards for Periodontal Epidemiology
	4.7 Other Diversity Expressions: Grouping Extent and Severity
	4.8 Comparability Within and Between Periodontal Epidemiologic Studies
		4.8.1	 Different Recording Protocols as Compromising Factors
		4.8.2	 Disease Levels as Compromising Factors
		4.8.3	 Validity of Periodontal Recordings
	4.9 Sifting the Evidence: Descriptive Periodontal Epidemiology
		4.9.1	 Age
		4.9.2	 Gender
		4.9.3	 Race/Ethnicity
		4.9.4	 Country/Region
		4.9.5	 Socioeconomic Factors
		4.9.6	 Behavioural Factors
		4.9.7	 Trends in Periodontal Diseases over Time
	4.10 The Way Forward in Periodontal Epidemiology?
	References
5: Malocclusions
	5.1	 Introduction
	5.2	 Classification
		5.2.1	 Malocclusion Classification
		5.2.2	 Malocclusion Classification in Clinical Settings
			5.2.2.1	 Angle’s Malocclusion Classification
			5.2.2.2	 Dewey’s Modification
			5.2.2.3	 Simon’s Classification
			5.2.2.4	 Ackermann and Proffit Classification
			5.2.2.5	 Andrew’s Six Keys
			5.2.2.6	 American Board of Orthodontics Discrepancy Index (ABO DI)
		5.2.3	 Malocclusion Classification in Epidemiological Settings
			5.2.3.1	 Index of Orthodontic Treatment Priority (Need) (IOTN)
			5.2.3.2	 Peer Assessment Rating (PAR)
			5.2.3.3	 Dental Aesthetic Index (DAI)
			5.2.3.4	 Index of Complexity, Outcome, and Need (ICON)
		5.2.4	 Summary
	5.3	 Epidemiology
		5.3.1	 Deciduous Dentition
		5.3.2	 Mixed Dentition
		5.3.3	 Permanent Dentition
	5.4	 Protective Factors and Risk Indicators for Malocclusions
		5.4.1	 Socioeconomic Conditions
		5.4.2	 Anthropometric Characteristics
		5.4.3	 Child Behavior
		5.4.4	 Maternal Characteristics
		5.4.5	 Preventable Diseases and Conditions Associated with Malocclusion
	5.5	 Impact of Malocclusion on Individuals’ Quality of Life
	5.6	 Final Considerations
	References
		Further Reading
6: Orofacial Pain
	6.1	 Introduction
	6.2	 Definition of Pain and Orofacial Pain
	6.3	 Diagnosis and Classification of Orofacial Pain
	6.4	 Measures and Instruments of Orofacial Pain
	6.5	 Epidemiology of Orofacial Pain
	6.6	 Epidemiology of Dental Pain
	6.7	 Conclusion
	References
7: Dental Fluorosis: Epidemiological Aspects
	7.1	 Introduction
		7.1.1	 Aetiology and Clinical Appearance of Dental Fluorosis
		7.1.2	 Historical Trend of Dental Fluorosis
		7.1.3	 Risk Factors for Dental Fluorosis
			7.1.3.1	 Fluoridated Water
			7.1.3.2	 Fluoride Toothpaste
			7.1.3.3	 Fluoride Supplements
			7.1.3.4	 Fluoride from Foods
		7.1.4	 The Measurement of Dental Fluorosis
			7.1.4.1	 Approaches in the Measurement of Fluorosis
			7.1.4.2	 Differential Diagnosis of Fluorosis
			7.1.4.3	 Fluorosis Indices Available
				The Dean Index [76]
				The Thylstrup and Fejerskov (TF) Index [77]
				The Fluorosis Risk Index (FRI) [79]
				The Tooth Surface Index of Fluorosis (TSIF) [78]
		7.1.5	 Public Opinion on Fluorosis
	References
8: Traumatic Dental Injuries
	8.1	 Introduction
	8.2	 Preliminary Concepts
		8.2.1	 Outcomes in Dental Traumatology
		8.2.2	 Study Designs and Measures of Frequency in Dental Traumatology
		8.2.3	 Etiology, Inferential Analysis, and Measures of Effect in Dental Traumatology
	8.3	 Epidemiology in Dental Traumatology
		8.3.1	 Prevalence and Distribution of TDI in Primary Teeth
		8.3.2	 Prevalence and Distribution of TDI in Permanent Teeth
		8.3.3	 Factors Associated with TDI in Permanent and Primary Teeth
			8.3.3.1	 Contextual Variables
			8.3.3.2	 Individual Variables
				Demographic Factors
				Socioeconomic Factors
				Psychosocial Variables
				Behavioral Variables
				Oral Factors
	8.4	 Impact of TDI
		8.4.1	 Impact of TDI in Primary Teeth on OHRQoL
		8.4.2	 Impact of TDI in Permanent Teeth on OHRQoL
	8.5	 Interventions in Dental Traumatology
		8.5.1	 Primary Prevention in Dental Traumatology
		8.5.2	 Secondary and Tertiary Prevention in Dental Traumatology
	8.6	 Conclusions
	References
		Further Reading
9: Epidemiology of Cleft Lip and Palate
	9.1	 Introduction
	9.2	 Embryology
	9.3	 Considerations
	9.4	 International Birth Incidence/Prevalence
		9.4.1	 Ethnicity
		9.4.2	 Sex
	9.5	 Environmental Risk Factors
		9.5.1	 Smoking
		9.5.2	 Alcohol
		9.5.3	 Folic Acid Intake
		9.5.4	 Maternal Obesity
		9.5.5	 Maternal Stress
		9.5.6	 Maternal Health
		9.5.7	 Socio-economic Status
		9.5.8	 Population Attributable Risk
	9.6	 Genetics
		9.6.1	 Genetic-Environmental Interactions
	9.7	 Quality of Life
		9.7.1	 Health Outcomes
	9.8	 Conclusion
	References
		Recommended Reading
10: Enamel Defects
	10.1	 Introduction
	10.2	 Amelogenesis Imperfecta (AI)
		10.2.1	 Prevalence of Amelogenesis Imperfecta
	10.3	 Acquired DDE in the Primary Dentition
		10.3.1	 Prevalence of DDE in Infants
		10.3.2	 Factors Associated with Acquired DDE in Primary Teeth
		10.3.3	 Hypomineralised Second Primary Molars
	10.4	 Acquired DDE in Permanent Teeth
		10.4.1	 Trauma
		10.4.2	 Illness and Medication
		10.4.3	 Molar–Incisor Hypomineralisation
	10.5	 Summary
	References
		Further Readings
11: Oral Cancer
	11.1 Introduction
	11.2 Measurement of the Disease Burden of Oral Cancer
	11.3 Standardization or Adjustment of Rates
	11.4 Measuring the Global Burden of Disease (Descriptive Epidemiology)
		11.4.1 Survival (or Time-to-Event) Studies
		11.4.2 Quality of Life Studies
	11.5 Assessing Associated Factors (Analytic Epidemiology)
		11.5.1 Tobacco Smoking and Alcohol Drinking Are Major Risk Factors
		11.5.2 Sociodemographic Characteristics Are Major Determinants
		11.5.3 Eating Habits Also Relate to Cancer Risk
		11.5.4 Occupational Exposures
		11.5.5 Oral Hygiene and Dental Status
		11.5.6 Human Papillomavirus (HPV) in Oropharyngeal Cancer
		11.5.7 Interaction and Mediation Between Risk Factors
	11.6 The Effectiveness of Health Services
	References
12: Dental Erosion
	12.1	 Introduction
	12.2	 Factors Associated with Dental Erosion
		12.2.1	 Behavioral Factors
	12.3	 Differential Diagnosis
	12.4	 Classification of Dental Erosion – Indices
	12.5	 Epidemiology of Dental Erosion
		12.5.1	 Final Considerations
	References
		Further Reading
13: Tooth Loss
	13.1	 Introduction
	13.2	 Distribution of Tooth Loss
		13.2.1	 Prevalence and Incidence of Tooth Loss
		13.2.2	 Distribution of the Number of Remaining Teeth
		13.2.3	 Distribution of the Burden of Tooth Loss
	13.3	 Measurements of Tooth Loss
		13.3.1	 Dental Examination and Self-Reported Measurements
		13.3.2	 Validity of Self-Reported Measurements
		13.3.3	 Categorization of Status of Remaining Teeth
	13.4	 Risk Factors/Predictors for Tooth Loss
		13.4.1	 Proximal Factors for Tooth Loss
		13.4.2	 Intermediate Factors for Tooth Loss
		13.4.3	 Distal Factors for Tooth Loss
	13.5	 Conclusion
	References
		Further Reading
14: Halitosis
	14.1	 Introduction
	14.2	 Methods of Diagnosing-Detecting Bad Breath
		14.2.1	 The Bad Breath Paradox
	14.3	 Prevalence of Bad Breath
	14.4	 Causes of Bad Breath
		14.4.1	 Mechanisms of Bad Breath Formation
		14.4.2	 Tongue Coating (Debris, Bacteria, and Dead Cells)
		14.4.3	 Periodontal Disease
		14.4.4	 Airways
		14.4.5	 Transitory Bad Breath
		14.4.6	 Systemic Diseases
		14.4.7	 Gastrointestinal Diseases
	14.5	 Treatment of Bad Breath
	14.6	 The Experience of a Halitosis Clinic in Rio de Janeiro from 1998 to 2004 (“Clínica do Tratamento do Hálito – CTH-RJ”)
	14.7	 Conclusion
	References
		Recommended Readings
		Further Reading
15: Oral Lesions in Soft Tissues
	15.1 Introduction
	15.2 Methodologies of Data Collection and Analysis of OML
		15.2.1 Clinical Examination
		15.2.2 Instruments of Measurement of the Occurrence of OML
		15.2.3 Limitations
	15.3 Studies on OML Prevalence
		15.3.1 Children and Adolescents
		15.3.2 Young and Middle-Aged Adults
		15.3.3 Old People
	15.4 The Use of Technology in Population-Based Epidemiological Studies
	15.5 Final Considerations
	References
II: Hot Topics
16: Causal Inference in Oral Health Epidemiology
	16.1 Introduction
	16.2 Historical Perspective
		16.2.1 Induction and Falsification
		16.2.2 Deterministic Causal Models: Necessary Causes and the Sufficient-Component Causes
		16.2.3 Probabilistic Causation and the Counterfactual Approach
	16.3 Statistical Versus Causal Association
	16.4 Causal Diagrams to Inform Stronger Analytic Designs
		16.4.1 Basic Components of Causal Diagrams
		16.4.2 Basic Principles of Causal Diagrams
	16.5 Randomized Experiments: The Only Option from Which to Infer Causality?
	16.6 Analytical Approaches for Causal Inference in Observational Data
		16.6.1 Marginal Structural Modeling
		16.6.2 Structural Equation Modeling
		16.6.3 Instrumental Variables
		16.6.4 Standardization and the Parametric G-Formula
	16.7 Conclusions
	References
17: Socio-Economic Inequalities in Oral Health
	17.1 Introduction
	17.2 Key Motivations for Investigating Oral Health Inequalities
	17.3 Theoretical Explanations for Socio-Economic Inequalities in Oral Health
	17.4 Operationalisation of Theoretical Explanations for Socio-Economic Inequalities in Oral Health
	17.5 Measurement of Socio-Economic Inequalities in Oral Health
		17.5.1	 Different Types of Measures of Social Inequality
		17.5.2 Levels of Aggregation
			17.5.2.1	 Socio-Economic Variations in Oral Health Between Populations
			17.5.2.2 Fallacies Arising due to Misspecification of Variables or Level
			17.5.2.3 Analytical Approaches
		17.5.3 Composite Measures of Socio-Economic Inequalities in Oral Health
		17.5.4 Measurement of Socio-Economic Inequalities in Oral Health: Scale of Measurement
	17.6 Advancements
		17.6.1 Intersectionality Theory
		17.6.2 Causal Inference and the Potential Outcome Approach
		17.6.3 Decomposition of Socio-Economic Inequalities in Oral Health
		17.6.4 Simulation Modelling
	17.7 Way Forward and Conclusion
	References
		Further Reading
18: Life Course Oral Health Epidemiology
	18.1 Introduction
	18.2 The Development of Life Course Epidemiology
		18.2.1 Biological Programming
		18.2.2 Evidence of Risk Accumulation from Birth Cohort Studies
		18.2.3 A Life Course Perspective on Health Inequalities
	18.3 Life Course Theoretical Models: Critical Periods and Lifelong Risk Accumulation
		18.3.1 Critical Period/Sensitive Period Models
		18.3.2 Accumulation of Risk
		18.3.3 Chains of Risk (Pathway Models)
		18.3.4 Life Course Oral Health
		18.3.5 Oral Health Across the Life Cycle: Epidemiological Studies in Oral Health
		18.3.6 New Zealand Study: Dunedin
		18.3.7 The Pelotas, Brazil Birth Cohort Studies
		18.3.8 The Role of Socio-Economic Factors Across the Life Course on Oral Health
		18.3.9 The Relationship Between General and Oral Health
		18.3.10 Longitudinal Assessment of Sugar Consumption and Dental Caries
	18.4 Intergenerational Approach
		18.4.1 Predictive Models
	References
		Further Reading
19: Sugar Consumption and Oral Health
	19.1 Introduction
	19.2 WHO Classification of Sugars and Guideline on Sugars Intake
		19.2.1 WHO Classification of Sugars
		19.2.2 Current WHO Guideline on Sugars Intake
	19.3 The Role of Free Sugars for Oral and General Health
		19.3.1 Free Sugars and Oral Health
			19.3.1.1 Dental Caries
				Dried Fruit
				Intrinsic Sugars Present in Fresh Fruits and Vegetables
				Milk Sugars
				Frequency or Amount of Free Sugars?
			19.3.1.2 Periodontal Disease
		19.3.2 Free Sugars and General Health
			19.3.2.1 Unhealthy Weight Gain
			19.3.2.2 Diabetes
			19.3.2.3 Cardiovascular Disease (CVD)
	19.4 Patterns and Trends in Free Sugars Consumption
	19.5 Social and Commercial Determinants of Sugar Consumption
	19.6 Policy Action to Reduce Sugar Consumption
	19.7 Conclusion
	References
20: Oral Health-Related Quality of Life
	20.1 Introduction
	20.2 The Concept of Quality of Life and Relevant Theoretical Frameworks
	20.3 OHRQoL Measures That Stood the Test of Time
	20.4 Measurement Properties and Key Characteristics
	20.5 How Have They Been Used? Applications
	20.6 Issues in OHRQoL Research: (Mis)interpretation
	20.7 What Way Forward?
	Appendix: Comprehensive List of Oral Health-Related Quality of Life Measures (. Tables 20.3, 20.4, and 20.5)
	References
		Further Reading
21: Ecosocial Oral Health Epidemiology
	21.1 Introduction
	21.2 Historical Evolution of Modern Epidemiology
	21.3 Social or Critical Epidemiology
	21.4 From Social to Ecosocial: New Integrative Paths
	21.5 The Impact of Ecosocial Theory on Definitions of Causality in Epidemiology
	21.6 Applications in ​​Oral Health Epidemiology
	21.7 Conclusion
	References
22: Use of Primary Care Settings to Collect Epidemiological Data
	22.1 Introduction
	22.2 Traditional Epidemiological Methods
	22.3 The Use of Primary Care as a Source of Epidemiological Data
		22.3.1 The Inherent Bias within Primary Care Data
		22.3.2 Accessing Data Routinely Collected by Dentists as Part of Their Assessment and Treatment of Patients
		22.3.3 Asking Dentists to Collect Additional Data from Patients During Their Treatment and Assessment of Patients: Using the Primary Care Workforce
		22.3.4 Using Primary Dental Care Premises to Access Patients by External Clinical or Non-clinical Staff for the Purpose of Capturing Epidemiological Data
		22.3.5 Using Primary Dental Care Sites to Recruit Subjects to Self-report Epidemiological Data. The Role of Technology in Primary Care Data Collection
	22.4 Connected Devices and Primary Care Recruitment and Data Triangulation
	22.5 Routine Data Collection: Hypothesis Generating or Service Informing
	22.6 Conclusions
	References
23: Big Data and Machine Learning
	23.1 Introduction
	23.2 “Big Data” – What It Is and Why It Is Useful for Oral Epidemiology
	23.3 Challenges of and Methods for Big Data Analytics
	23.4 Spurious Correlations
	23.5 Causal Methods for Observational Studies
		23.5.1 Differences-in-Differences
		23.5.2 Regression Discontinuity
		23.5.3 Propensity Score Matching
		23.5.4 Instrumental Variables
	23.6 Machine Learning in Big Data
	23.7 Machine Learning Algorithms
		23.7.1 Random Forests
		23.7.2 Gradient Boosted Trees
		23.7.3 Artificial Neural Networks
	23.8 Implementation of Big Data Acquisition, Storage, and Processing
	23.9 Conclusion
	References
24: Epigenetics in Oral Health
	24.1 Introduction
	24.2 Defining Epigenetics
	24.3 Epigenetic Molecular Mechanisms
		24.3.1 DNA Methylation
		24.3.2 Histone Modification
		24.3.3 DNA Methylation and Histone Acetylation Interaction
		24.3.4 Non-coding RNA
	24.4 Examples from Biology and Medicine
		24.4.1 Genetic Imprinting
		24.4.2 Cancer
		24.4.3 Environmental Stressors
		24.4.4 Behaviour
	24.5 Epigenetics in Oral Health
		24.5.1 Tooth Development
		24.5.2 Dental Caries
		24.5.3 Immunology and Periodontitis
		24.5.4 Oral Cancer
	24.6 Clinical Applications
		24.6.1 Personalised Medicine – The Potential of Epigenetics for Diagnosis and Therapy
		24.6.2 Epigenetic Modifications as Biomarkers of Exposure, Disease and Treatment Response
		24.6.3 Epigenetic Tools to Modify Gene Expression
		24.6.4 Epidrugs
		24.6.5 Other Fields of Research
	24.7 Conclusion
	References
25: The Relationship Between Periodontal Diseases and Chronic Diseases
	25.1 Introduction
	25.2 Biological Plausibility and Conceptual Models
	25.3 Temporality as an Issue
	25.4 A Glance into Confounding and Mediation
	25.5 The (Almost) Neglected Case of Collider Variables
	25.6 The Role of Smoking in the Association Between Periodontal and Systemic Diseases
	25.7 Biological Plausibility of the Association Between Periodontitis and Systemic Diseases
		25.7.1 Direct or Indirect Mechanisms?
		25.7.2 Periodontitis and Cardiovascular Disease
			25.7.2.1 Evidence
		25.7.3 Periodontitis and Adverse Pregnancy Outcomes
	25.8 Biological Plausibility of the Association Between Systemic Diseases and Periodontitis
		25.8.1 Obesity and Periodontitis
			25.8.1.1 Evidence
		25.8.2 Metabolic Syndrome (MetS) and Periodontitis
			25.8.2.1 Evidence
	25.9 Diabetes: The Issue of Diabetes and the Claim for a Bidirectional Relationship
		25.9.1 Evidence: Periodontitis and Diabetes
		25.9.2 Evidence: Diabetes and Periodontitis
	25.10 Other Features That May Influence the Association Between Periodontal and Systemic Conditions
		25.10.1 Hawthorne Effect
		25.10.2 Compliance Bias
		25.10.3 Sample Size Bias
		25.10.4 Misclassification Bias
		25.10.5 Attrition Bias
		25.10.6 Admission Rate Bias
		25.10.7 Allocation Bias
		25.10.8 Lack of Blinding
	25.11 Conclusion
	References
26: Dental Health Services Epidemiology
	26.1 Introduction
	26.2 Defining Health Services Research
	26.3 Conceptual Models of Health Services Research
	26.4 Use of Health Services
	26.5 Types of Health Services Research
	26.6 Dental Visits
		26.6.1 Inequalities as a Focus of Health Services Research into Visits
		26.6.2 Predisposing-Enabling-Need Model as a Framework for Dental Visits
		26.6.3 Check-Up Visits
		26.6.4 Problem-Based Visits
		26.6.5 Favourable Visit Patterns
		26.6.6 Expenditure on Care/Visits as an Outcome
	26.7 Dental Services
		26.7.1 Changes in Dental Services
		26.7.2 Relative Value Units
		26.7.3 Applications of Dental Services Research
		26.7.4 Linking Services to Outcomes
	26.8 Conclusion
	References
		Further Reading
27: Bioethics of Epidemiological Oral Health Studies
	27.1 Codes of Conduct for Research
		27.1.1 The Nuremberg Code [3]
		27.1.2 The Declaration of Helsinki [4–6]
		27.1.3 The Belmont Report [7]
	27.2 The Implications of Ethical Principles for the Conduct of Bioethical Research
		27.2.1 Respect for the Individual
			27.2.1.1 Voluntariness
			27.2.1.2 Comprehension
			27.2.1.3 Disclosure
		27.2.2 Justice
			27.2.2.1 Justice in the Selection of Potential Participants
			27.2.2.2 Justice in Distribution of the Benefits and Risks of Research Amongst Participants
		27.2.3 Beneficence
	27.3 Ethical Review Processes/Institutional Review Boards
	27.4 Summary
	References
		Further Reading
28: Epidemiology, Politics, and Dental Public Health
	28.1 Introduction
	28.2 New Public Health
	28.3 Dental Public Health
	28.4 Theoretical Basis of the Influence of Social Policies on Population Oral Health and Inequalities
		28.4.1	 How Social Policies Affect Oral Health and Inequalities?
	28.5 Evidence on the Relationship Between Social Policies and Population Oral Health (Including Inequalities)
		28.5.1	 General Political Factors and Oral Health
		28.5.2	 Certain Specific Social Policies and Population Health
		28.5.3	 Particular Policies Aimed to Impact Oral Health
	28.6 Conclusion
	References
29: Water Fluoridation
	29.1 Introduction
	29.2 Evolution of the Oral Epidemiological Evidence
	29.3 Findings from Across Clinical Trials to Monitoring Studies
	29.4 Understanding Heterogeneity and Bias in Studies of Water Fluoridation
	29.5 Study Design and Bias
	29.6 Exposure to Fluoride in Drinking Water
		29.6.1	 Exposure: Induction Period
		29.6.2	 Exposure to Naturally Occurring Fluoride in Early Research
		29.6.3	 Exposure to Water Fluoridation: The First Community Trials
		29.6.4	 Reviews of Community Fluoridation Trials
		29.6.5	 Comparative Studies with Concurrent Controls: Continuous Residence or Lifetime Exposure to Fluoridated Water
		29.6.6	 Lifetime Exposure to Fluoridated Water Among Adults and Older Adults
	29.7 Caries Outcomes
		29.7.1	 Background
		29.7.2	 Natural History and Intraoral Distribution of Caries
	29.8 Alternative Caries Outcome Measures
		29.8.1	 A Different Approach: Incidence and Increment of Caries
	29.9 Conclusions
	References
30: Teaching Oral Epidemiology
	30.1 Introduction
	30.2 Regulation of the Teaching Curriculum
	30.3 Course Documentation and Design
		30.3.1 Course or Study Guide
		30.3.2 Learning Objectives
		30.3.3 Methods of Teaching and Learning
	30.4 Curriculum Content
	30.5 Assessment Methods
	30.6 Quality Assurance Methods
	30.7 Conclusions
	References
		Further Reading
III: Methods
31: Measurement Instruments for Use in Oral Epidemiology
	31.1 Introduction
	31.2 Epidemiology as a Measuring Exercise
	31.3 Points to Consider When Selecting Measurement Instruments
		31.3.1 What to Do When Instruments Are Available and Ready to Use (Scenario 1)
		31.3.2 Recommendations When Instruments Are Available, but Their Use in the Given Sociocultural Context Requires Additional Work (Scenario 2)
		31.3.3 Procedures When No Instruments Are Available or Those That Exist Are Insufficient, Requiring the Development of New Ones for the Underlying Research to Be Conducted (Scenario 3)
	31.4 Conclusions
	References
		Further Reading
32: Reproducibility and Validity of Diagnostic Tests
	32.1 Introduction
	32.2 Reproducibility of Diagnostic Tests
		32.2.1 Percentage of Agreement
		32.2.2 Kappa Statistics
			32.2.2.1 Tendencies in Studies About the Reproducibility of Tests for Dental Caries Detection
		32.2.3 Intraclass Correlation Coefficient
		32.2.4 Dice Index
	32.3 Validity of Diagnostic Tests
		32.3.1 Sensitivity and Specificity
		32.3.2 Predictive Values
		32.3.3 Likelihood Ratios
		32.3.4 False-Positive Rate (FPR) and False-Negative Rate (FNR)
		32.3.5 Correct Classification
		32.3.6 Youden’s J Statistic
		32.3.7 Diagnostic Odds Ratio
		32.3.8 Receiver Operating Characteristic Curve
			32.3.8.1 Tendencies in Studies About the Reproducibility of Tests for Dental Caries Detection
		32.3.9 Bayes’ Theorem
	32.4 Final Considerations
		32.4.1 Outlook
		32.4.2 Closing Remark
	References
33: Quantitative Bias Analysis in Dental Research
	33.1 Introduction
	33.2 Do We Require Bias Analysis?
		33.2.1 When Is Bias Analysis Not Essential?
		33.2.2 When Do We Essentially Require Bias Analysis?
	33.3 When to Plan Bias Analysis?
	33.4 What Are the Different Forms of Bias Analyses and Which One to Study?
		33.4.1 Selection Bias
		33.4.2 Unmeasured Confounding
		33.4.3 Information/Misclassification/Measurement Bias
	33.5 Example
	33.6 Presenting the Results from Bias Analysis
	33.7 Conclusion
	Appendix A: Stata Code for Conducting the Bias Analysis
	Appendix B: R Code for Plots
	References
34: Reviews Systematic and  Meta-analysis
	34.1 Introduction
	34.2 Systematic Reviews
		34.2.1 Reviews of Observational Studies: Controversies, Reality and Needs
	34.3 Resources
	34.4 Control and/or Assessment of Possible Biases and Appropriate Use of Meta-analysis
		34.4.1 The Control of Bias in the Process of Data Collection
			34.4.1.1 Publication and Identification Bias
			34.4.1.2 Bias in the Selection and Quality Evaluation of the Studies
			34.4.1.3 Data Extraction Bias
			34.4.1.4 Bias in Systematic Reviews of Observation Studies
	34.5 Data Synthesis: Meta- and Network Meta-Analysis
		34.5.1 Treatment Effects in Meta-Analysis
			34.5.1.1 The Choice of a Statistical Model for Meta-Analysis
			34.5.1.2 Investigating Heterogeneity, Robustness and Bias in the Meta-Analysis
		34.5.2 Network Meta-Analysis
		34.5.3 Synthesis of Data for Observational Studies
	34.6 Applying Systematic Review Techniques for Health Economics or Implementation Research
	34.7 Conclusions
	References
Index