Lecture 1.pdf

DENT 4407 Research Methods in Dentistry Introduction to Dental Research Dr. Gülşilay SAYAR, DDS,PhD Associate Professor Bahçeşehir University School of Dental Medicine Department of Orthodontics [email protected] References Research Methods In Dentistry Fahimeh Tabatabaei Lobat Tayeb...

DENT 4407 Research Methods in Dentistry Introduction to Dental Research Dr. Gülşilay SAYAR, DDS,PhD Associate Professor Bahçeşehir University School of Dental Medicine Department of Orthodontics [email protected] References Research Methods In Dentistry Fahimeh Tabatabaei Lobat Tayebi Introduction to Dental Research Introduction to Dental Research What Is Research? Scientific research is a rational approach that allows the examination of problems to be solved and the discovery or formulation of precise answers to questions. It is built on the work of other scientists, can be generalized, and generates new questions. The ultimate goal of the research is to create the knowledge essential for improving health. The process of research is characterized by the fact that it answers questions in an organized , scientific , and systematic manner. Introduction to Dental Research Questions are required for research, and research always arises from a problem to be solved. Without a specific question, your research will be aimless. In other words, there is no research where there is no question. Therefore, by stating your question, you will clarify what your study intends to address. Finding the answer to the research question will be the objective of your research. Introduction to Dental Research Organized research begins with a plan or proposal. Nonplanned research is often inefficient, and it may never lead to the researcher’s correct answer. Introduction to Dental Research The scientific method means that the study is based on reproducibility, feasibility, and reliability, which we will explain further in the following chapters. Introduction to Dental Research Finally, using a systematic process means following clearly defined steps in the research to achieve an accurate answer: If your approach is deductive , you should: (1) formulate the research question, (2) predict the answer to the research question in the form of a hypothesis, (3) design a plan, (4) test the hypothesis, and (5) evaluate and report the results which confirm or reject your hypothesis. Introduction to Dental Research For example, after treating a carious-exposed tooth using calcium hydroxide and composite, you noticed the dentin bridge formation under restoration. Your question is: What is the reason for the formation of the dentinal bridge? You hypothesize that calcium hydroxide caused it. To test this hypothesis, you design a plan. After examining the effect of calcium hydroxide on dental pulp stem cells, you can report that your hypothesis has been confirmed or rejected. Introduction to Dental Research Therefore, one of the basic steps in any research project is to choose the research approach. This choice depends above all on the nature of the problem and the phenomenon being studied. As the deductive approach is more prevalent in dental research, we will focus on this approach in this lecture. Introduction to Dental Research Key concepts in the research literature Method: The word method may refer to a tool, instrument, experiment, technique, and test to set up, conduct, collect, analyze, and evaluate data for answering the research question. Observations, experiments, and statistical approaches are all examples of the methods employed to conduct the research. Introduction to Dental Research Methodology: The research methodology is broader than the method and refers to several methods used to efficiently investigate the research hypothesis and achieve the objective. The methodology may include subsections like “Research Design,” “Protection of Human Rights,” “Instrumentation,” “Data Collection and Analysis.” Introduction to Dental Research Methodology: Methodology implies the correct application of the method, explanations behind the decision of your specific methods (the rationale), and the recognition of the criteria for choosing a method. Introduction to Dental Research Variable is the measurable factor that can vary during research, can have more than one value, and is involved in answering the research question. The variable must also be directly observable (sex, color of eyes), or if it is not directly observable (time, temperature, proportion, pH), it can be measured by another measuring instrument (pH meter). The cause, risk factor, or the variable that can be manipulated in the research method is called the independent variable. Introduction to Dental Research The dependent variable is the effect, outcome, or the variable that responds to changes and would be analyzed to meet the objective. The independent variable can be changed/manipulated/controlled at given levels/doses/values/types by the researcher. Therefore, you can purposefully change the independent variable, which causes a change in the dependent variable (the reverse is impossible, which means the dependent variable cannot cause any change in the independent variable). The dependent variable should be measurable, and you should know how to measure it. Introduction to Dental Research We say that an association (correlation) exists between two variables when a change of one variable coincides with the shift in the other variable. An association can be positive or negative and proportional or nonproportional. The association is causal when a change in the independent variable (exposure) leads to or causes a difference in the dependent variable (disease). Introduction to Dental Research For example, you may assess patients regarding the use of restorative materials and the location of caries. If the results show that restoration selection depends on tooth type and surfaces, there is an association between the two variables. Introduction to Dental Research Hypothesis, in simple terms, is a statement in response to the research question and should be stated based on the researcher experiences and the findings of previous studies. This statement can be proven or rejected. To write a hypothesis, the researcher must determine the variable or groups and predict the relationship or the difference between them. The null hypothesis (H0) usually predicts no difference between the control and the study group, while the alternative hypothesis assumes a difference between groups or association among the variables. Introduction to Dental Research Hypothesis plays a guiding role in the research process and is only validated after experimentally testing. Based on the specific aims of your research, you may have several hypotheses. In a good research design, rejecting a null hypothesis will construct another null hypothesis, and the study will continue. Introduction to Dental Research The participants/samples are drawn from a population with determined characteristics. As the population of interest is usually substantial, and it is impossible to work directly on all of them, most research studies involve observing a sample from a defined population. Sampling is the process of choosing portions of the population to observe and study. The sampling method can be probable (random) or non-probable. Introduction to Dental Research It is essential to be aware of the difference between random sampling and random assignment/allocation. While random sampling is considering a known chance (greater than zero) of participation for every member of the population to be selected as subjects, random assignment means that after selecting subjects, you should also determine a method of randomly assigning the sample into the study/ control groups. Introduction to Dental Research Finally, one of the most crucial parts of the research is the researcher. The researcher is any person carrying out studies respecting a rigorous methodology to provide new knowledge. A researcher needs to be passionate about his/ her work, have a good plan, be patient while doing research, and be persistent in achieving the goal. Introduction to Dental Research Among the critical qualities of researcher leading to success in research, we can cite: • A curious mind to find new facts. • Integrity for the value of the scientific method. • An analytical mind capable of practicing critical thinking. • Receptivity to criticism at the professional level. • Open-mindedness and the ability to see the meaning of unexpected observations. • Objectivity. Introduction to Dental Research Types of Dental Research The type of research significantly impacts the method of data collection and analysis, and if not chosen correctly, it can lead to erroneous results or an inability to answer the research question. Therefore, it is imperative to decide on the type of research before starting the project because you cannot change it during the study. Introduction to Dental Research Types of Dental Research Based on the Time Based on the time, the researcher observes the subjects/patients at a given time (cross-sectional studies) or during a continuous period (longitudinal studies). Introduction to Dental Research Types of Dental Research Based on the Time In cross-sectional or prevalence studies, you want to define “what is happening.” Like taking a picture with a camera, you need to observe all samples of different groups once at the same point in time or over a short period at the present moment. When you simultaneously compare the salivary cytokine levels of periodontally healthy subjects and subjects with chronic periodontitis, your study is cross-sectional. Introduction to Dental Research In longitudinal studies, the same group is observed continuously or repeatedly over a period (like a movie) to examine changes over time and understand the relationship between variables. This study is more accurate than cross-sectional and can be utilized for discovering the predictors of diseases. When you select two groups of subjects with/without a high level of a salivary cytokine and recall them periodically to evaluate the development of periodontitis in each group, subjects are enrolled in a longitudinal study. The longitudinal research can be retrospective or prospective. Introduction to Dental Research Introduction to Dental Research Retrospective studies concern any study for which exposure has occurred in the past, and data will be collected after the exposure or intervention through interviews or recorded information of patients. This method aims to analyze and interpret past events to predict similar events in the future. In other words, this method expresses “what happened.” Assuming that you are selecting a group of patients who previously received direct posterior resin-based composite restorations, you are conducting a retrospective longitudinal study if you evaluate the survival rate of their restoration Introduction to Dental Research In the prospective study, the research starts now, and the data will gradually be collected to determine the exposure. You aim to express “what will happen” regarding the etiology of a disease or the efficacy of an intervention. You can analyze salivary biomarkers of bone loss in two sample groups at risk or no risk of periodontal disease to see in which group more bone loss will occur. Prospective studies could be interventional non-interventional (observational ). (experimental ) or Introduction to Dental Research Non-interventional studies involve only questionnaires completed at a consultation or routine follow-up of participants. If a group of patients recently received resin-based composite restorations, and you only examine their restorations every 6 months for 12 years, your study is observational, while, if you select a group of patients, repair their teeth by composite restorations after assigning them to different groups, and then follow up with them over a period, your study is prospective and interventional. Introduction to Dental Research Based on the Location Based on the location of the data collection, the research can be divided into two categories: field research and library research. Field research involves the researcher’s own observations and data collection. In library research , the data is already available and should only be categorized. Systematic review and meta-analysis are the common forms of library research. Introduction to Dental Research Introduction to Dental Research Based on the Type of Data Depending on the data type, two kinds of studies can be identified: Qualitative and Quantitative If the information received or collected is not subject to statistical analysis but is based on an analysis beyond numbers, we refer to it as qualitative research. Here, you do not deal with numbers and statistics but rely on data explanation and interpretation of a small sample size. Introduction to Dental Research Based on the Type of Data In contrast to qualitative research, the emphasis in quantitative research is on statistics. It aims to collect quantifiable data and statistically analyze them to search for correlation (association) between variables or differences between groups. In this approach, sampling is critical to be representative of the population. Introduction to Dental Research Introduction to Dental Research Based on the Application Based on the outcome or purpose of the study, the research can be categorized into three types: Fundamental (basic), Developmental, Applied Introduction to Dental Research Introduction to Dental Research Fundamental or Basic Research Fundamental research aims to identify new problems, discover facts, recognize phenomena, test theories, and generate knowledge. This research is concept-oriented and is the primary source to produce new knowledge for applied and developmental research. Introduction to Dental Research Introduction to Dental Research Applied Research Introduction to Dental Research Developmental Research Developmental research aims to improve and develop the previous devices, processes, systems, or existing situations. Other examples of developmental research in dentistry are: 1. Improvement of an ultrasonic handpiece and its clinical evaluation. 2. Animal study for assessment of bone particles as implant material. Introduction to Dental Research Introduction to Dental Research Based on the Main Question or Objective Research in this category can be divided into exploratory, descriptive, and analytical research. Each of these types is structured in response to the main question of the study. Introduction to Dental Research Exploratory Research Exploratory research consists of characterizing a phenomenon so that it appears familiar. describing or Examples: • Are there any viable cells in the pulp of necrotic teeth? • Are there any bacteria inside the disinfected root canal of a tooth? • Does the amount of fluoride in drinking water vary in different parts of the city? Introduction to Dental Research Exploratory research can be classified into case reports and case series . A rare disease, a new symptom of a known disease, a new treatment, or the destructive effect of an intervention is reported in the case reports, and there is no control group. Case series are based on reports of a series of cases of a given pathology or a series of treated patients without a specific control group assignment. Introduction to Dental Research Descriptive Research When the researcher accepts the exploratory research results and begins to describe the created phenomenon, he/she enters the descriptive research process. For example, what is the prevalence or rate of caries in a population? What are the characteristics of this population (age, race, socioeconomic)? What are the radiographic or clinical symptoms? Introduction to Dental Research Descriptive studies are cross-sectional surveys. In cross-sectional surveys, cause-and-effect data are collected simultaneously, without determining the time sequence. They do not attempt to test a hypothesis about an association. They provide a prevalence rate at a point in time (point prevalence) or over a period (periodic prevalence). Introduction to Dental Research Analytical or Explanatory Research Analytical or explanatory research clarifies the relationships between phenomena and determines why such phenomena occur or under what conditions. In this type of research, the researcher seeks to answer the “WHY” question and discover the cause or determine the association between exposure to risk factors and disease. In other words, the objective of this type of research is to examine the causal relationship of variables. Introduction to Dental Research Analytical research is divided into two types observational and experimental (interventional) studies based on the assignment to exposure. Observational analytical studies , which implicate only observing what is happening, do not involve any intervention. Observational analytical studies could be prospective or retrospective, case-control, Cohort. Introduction to Dental Research Introduction to Dental Research Suppose that you aim to “determine the relationship between amalgam restorations and periodontitis.” Your analytical research method is case-control if you start with the selection of patients with periodontitis (case group) and healthy people (control group), Here, amalgam restoration is an independent variable (the exposures of interest), and periodontitis is a dependent variable. Introduction to Dental Research Introduction to Dental Research In cohort research, another type of observational analytical study that is more common than case-control in dental research, groups are divided according to the independent variable. The classic strategy of cohort studies is first to take a reference population without a given disease. Some individuals of this population present characteristics of interest for the study (exposed group), while others do not present them (unexposed group or control). Both groups should be free from the pathology considered at the start of the study. Observation of the two groups (with or without exposure) continues to identify the disease’s incidence over a given period. Introduction to Dental Research The steps in the prospective cohort study are as follows: 1. The population of interest is determined. 2. Disease-free samples are selected in this population. 3. Some individuals in the study population were in contact with the risk factor (exposed), and some were not exposed to the risk factor. 4. At different time points, the occurrence or nonoccurrence of the disease is examined in each group. Introduction to Dental Research When the cohort study, the research begins now, and the information is collected in the future (prospective) If the study design requires that you select individuals belonging to a specific population at a particular point in the past and then follow these individuals from that point in the past to “today,” the study iscalled a retrospective cohort study. Introduction to Dental Research Randomizing the treatment allocation is very important in the randomized controlled trial (RCT) as the most powerful scientific research tool. Proper randomization can reduce the risk of severe imbalance of these factors in the various study groups. If the subjects in question are all available before the study begins, they can be randomly assigned into the control and experimental group after matching in terms of intervening variables (randomized matched controlled trial (RMCT) ). Introduction to Dental Research Introduction to Dental Research Blinding is another crucial characteristic of clinical trials. A double-blind trial is a study where both the researcher team (including the statisticians responsible for analyzing the data and the investigators who write down the trial results) and the patient do not know whether the patient is in the experimental group or the control group. Introduction to Dental Research The randomized split-mouth trial (a design of randomized controlled trial) is specific to research in dentistry. The split-mouth trial is defined as a study in which different sites in the oral cavity (tooth, quadrant, or jaw) of a patient’s mouth will be randomly assigned to either the experimental treatment or control. Introduction to Dental Research The split-mouth • Dental surgery: “prophylaxis versus placebo treatment for infective and inflammatory complications of surgical third molar removal” . • Periodontology: “antimicrobial photodynamic therapy as an adjunct to non-surgical treatment of aggressive periodontitis”. • Orthodontics: “effect of micro-osteoperforation on the rate of canine retraction” Introduction to Dental Research Introduction to Dental Research Introduction to Dental Research Introduction to Dental Research How to Find the Field or Area of Interest? The selection of the field or area of interest is the first step in conducting the research. Determining what you want to study (the subject area of research) and, subsequently, the topic for implementing any research project depends on many factors. The choice is influenced by considerations such as the possession of domain knowledge, your experiences, studies, needs, interests, and educational environment. The idea may come from personal experiences in everyday life, articles relating to the field of study, or research priorities of research centers. Introduction to Dental Research To find a field of research that attracts you, use the following questions: • When dealing with dental patients or reading an article recently, did I encounter a topic that piqued my interest or made me think for hours? • Is there an aspect of a subject in dentistry that I am interested in learning more about? • Do I have a view on a current scientific controversy? Introduction to Dental Research After selecting a research area, to understand if you are undoubtedly interested in that, ask the following questions: • Why do I want to work on this subject? • Will I still be interested in dealing with this subject in a few months, or even for years, as part of my career? Introduction to Dental Research Previous Studies One of the most important sources for finding a topic or subject is a previous study because it is always limited and specific. Each research project answers one or more questions but at the same time creates other questions or offers suggestions for further studies based on the limitations of the research. Therefore, previous studies can be used—as a source—to find new questions and choose a new topic. Systematic reviews that often focus on a particular topic are also excellent sources for finding new research subjects. Introduction to Dental Research Three essential steps to reach the research topic include observing, thinking, and reading about your area of interest. These steps would help you to limit your “research area” gradually. Introduction to Dental Research Observing Observation is an active process and the first step in gathering information about the research problem. When a patient comes to you and complains of a dental problem, you first receive information about the chief complaint and medical and dental history. Then by physical evaluation, clinical and radiographic examination, and the assessment of the performance of his/her existing restorations, you can have a complete view of the patient’s condition. Introduction to Dental Research Handling Large Volume of Literatures as New Challenge in Performing Research Introduction to Dental Research What Resources? Thoughtful reading is a systematic and planned study. When searching for information related to our topic, we must also consider the quality of the study. The literature includes academic articles and books that sometimes could be found on scientific websites like Scopus, PubMed, and ScienceDirect. Introduction to Dental Research Introduction to Dental Research Introduction to Dental Research Thank you...