Types of data.

In most, if not all, studies we collect data to obtain information about an area of research in which we have an interest. For example, we might want to know the level of dental caries in our area. In order to discover this we might need to observe a number of different variables, which could include, age, sex, number of teeth, cavities, fillings, extraction, pain, sepsis and quality of life.

How to increase response rates to postal questionnaires.

Data Sources: Fourteen electronic databases were searched, namely Cochrane Controlled Trials Register, CINAHL (Cumulative Index to Nursing & Allied Health Literature), ERIC (Education Resources Information Center) PsycLit, Dissertation Abstracts, Medline, Embase, Social Science Citation Index, Science Citation Index, Social Psychological Educational Criminological Trials Register, EconLit, Sociological Abstracts, Index to Scientific and Technical Proceedings, and National Research Register. Literature reviews and meta-analyses were inspected for eligible trials and two journals (Public Opinion Quarterly and American Journal of Epidemiology) were searched by hand.

Study Selection: Studies included were randomised controlled trials of methods to increase response rates to postal questionnaires.

Patient delay in reporting oral cancer is poorly understood.

Data Sources: Studies were sourced using databases as follows: Allied and Complementary Medicine, CANCERLIT, CINAHL, Embase, Medline, and PSYCHINFO. Researchers known to be involved in this area of study were contacted and bibliographic references were manually searched.

Study Selection: Studies were only included if they were published in the English language; were restricted to participants who had malignancies of the oral cavity; at least 90% of these patients had a histological diagnosis of squamous cell carcinoma; and if they reported data allowing statistical analysis of the duration of patient delay in reporting their cancer.

Can I intrude?

Data Sources: Studies were identified using Medline, PubMed, Medline In-Process and Other Non-Indexed Citations, all evidence-based medicine reviews (Cochrane Database of Systematic Reviews, ACP (American College of Physicians) Journal Club, Database of Reviews of Effectiveness (DARE) and CCTR (Cochrane Controlled Trials Register), Embase, Web of Science and LILACS(Latin American and Caribbean Health Sciences).

Study Selection: Studies included were clinical trials in humans where the intrusion of permanent incisors was determined using cephalometric radiograph superimpositions.

Data Extraction And Synthesis: A qualitative synthesis of all included studies was conducted, along with a fixed-effects meta-analysis of two studies that employed the same treatment method.

Prevention of oral mucositis in cancer patients treated with chemotherapy or radiotherapy.

Data Sources: The Medline, Embase and CINAHL databases were used to source studies, along with the reference lists of identified articles.

Study Selection: Studies were restricted to randomised controlled trials (RCT), written in English, where the outcome of mucositis was recorded using the World Health Organization score or the NCI-CTC (National Cancer Institute-Common Toxicity Criteria) score, the absence or presence of ulcerations, or the presence or absence of grades 3 and 4 mucositis.

Data Extraction And Synthesis: A total of 45 studies was included in a meta-analysis.

What is the most effective adhesive for attaching orthodontic bands?

Data Sources: The Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline and Embase were used and a search of the internet also undertaken. There was no restriction with regard to publication status or language of publication.

Study Selection: Randomised controlled trials (RCT) and controlled clinical trials (CCT), including split-mouth studies, of adhesives used to attach orthodontic bands to molar teeth were selected.

Integrating evidence-based teaching into to clinical practice should improve outcomes.

Data Sources: Sources used were Medline, Embase, the Education Resources Information Centre , Cochrane Controlled Trials Register, Cochrane Database of Systematic Reviews, the Database of Abstracts of Reviews of Effects, Health Technology Assessment database, Best Evidence, Best Evidence Medical Education and Science Citation Index, along with reference lists of known systematic reviews.

Study Selection: Studies were chosen for inclusion if they evaluated the effects of postgraduate evidence-based medicine (EBM) or critical appraisal teaching in comparison with a control group or baseline before teaching, using a measure of participants' learning achievements or patients' health gains as outcomes.

Data Extraction And Synthesis: Articles were graded as either level 1 (randomised controlled trials (RCT)) or level 2 (non-randomised studies that either had a comparison with a control group), or a before and after comparison without a control group.

Centre for Health Information Quality.

The Centre for Health Information Quality (CHIQ; www.hfht.org/chiq), was established in 1997 by the UK government's Department of Health.

The quality of systematic reviews in dentistry.

Data Sources: Sources of reviews were the Database of Reviews of Effectiveness (DARE) and completed systematic reviews registered by the Cochrane Oral Health Group in the Cochrane Library.

Study Selection: All systematic reviews that examined the effectiveness of interventions for oral, dental and craniofacial disorders and diseases were eligible for inclusion.

Data Extraction And Synthesis: A quality assessment checklist was completed for each study.