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Table 2 Strengths and limitations of included studies according to the STROBE checklist

From: Consequences of early extraction of compromised first permanent molar: a systematic review

Reference Strengths Limitations Scores
Ast et al., 1961 [12] • Clear objectives
• Ascertainment of outcome and reliability of examiners were described
• Extraction and non-extraction groups were matched for age
• Cross-sectional study with convenience sample
• The study design was not mentioned
• The sample size and power of the sample was not calculated
• The study setting was not clear
• Retrospective study
• Age at time of extraction was not mentioned
• Potential confounders and participant characteristics were not described
• Weak methodology (method of assessment of molar relationship was not uniform or acceptable)
5*
Oliver et al., 1988 [15] • The objectives were clear
• The sample was stratified; however, the eligibility criteria for participant selection was not clear
• Age of participants at time of extraction and evaluation of consequences were clear
• Examination was carried out by one examiner
• Intraexaminer reproducibility was established
• Numbers of participants used for each examination was mentioned with reasons for withdrawal
• The study design was not mentioned
• There was no sample size power calculation
• Potential confounders were not addressed
9**
Telli and Aytan, 1989 [7] • The objectives were clear
• Age of participants at time of extraction and evaluation of consequences were clear
• Split-mouth (extraction and non-extraction sides in the same patient)
• Method used to assess variables was powerful (superimposition of cephalometric radiographs)
• The study design was not mentioned
• There was no sample size power calculation
• The location from which the sample was recruited was not clear
• Reason for “non-participants” was not mentioned
10**
Ay et al., 2006 [13] • The objectives were clear
• The age was clear both at the time of extraction and evaluation of consequences
• The setting was clear (Department of Oral and Maxillofacial Surgery of Cumhuriyet University, Sivas, Turkey)
• Participant characteristics were mentioned
• The same investigator undertook all measurements, and the reproducibility of the method was tested
• The study design was not mentioned
• Retrospective
• The number of extracted teeth was not clear
• No sample size power calculation was performed
9**
Yavuz et al., 2006 [19] • The objectives were clear
• The location of participant recruitment was clear
• The age was clear both at the time of extraction and evaluation of consequences
• Reliability testing was done
• Extraction and non-extraction sides were in the same patient
• All assessments were performed by one examiner
• Intraexaminer reproducibility was established
• The study design, method for selecting the sample, and period of recruitment were not mentioned
• No sample size power calculation
• A retrospective study design
• Potential confounders were not addressed
• Follow-up duration was not clear
11**
Jälevik and Möller, 2007 [14] • The objectives were clear
• The setting and location of patient recruitment were clear
• The age of participants at time of extraction and time of evaluation of consequences were clear
• Methods used to assess variables were powerful (panoramic X-rays, bitewings, casts and photographs)
• The study design was not mentioned
• Period of recruitment was not mentioned
• A cross-sectional study design
• No sample size power calculation was performed
11**
Rãducanu et al., 2009 [16] • The objectives were clear
• The study design was clear
• The location and duration of participant recruitment were clear
• Intraexaminer and interexaminer reliability tests were performed
• No sample size power calculation was performed
• The age at extraction and at evaluation of consequences was not clear
• Numbers of each category were not mentioned, only percentages.
• Convenience sample
• Retrospective study
• Potential confounders were not addressed
• Small sample size
13**
Normando and Cavacami, 2010 [20] • The objectives were clear
• Cases and controls were matched for age, gender, and location
• The study design was not mentioned
• The sample size power was not calculated
• The setting in which the study was performed was not mentioned
• Age at extraction time was not mentioned
• Retrospective study from records
• Follow-up time was not clear
13**
Teo et al., 2013 [18] • The objectives were clear
• The location and duration of participant recruitment were clear
• All assessments were undertaken by one examiner
• Intraexaminer repeatability was done
• The study design was not mentioned
• No sample size power calculation was performed
• Retrospective study from records
11**
Rahhal, 2014 [21] • The objectives were clear
• The setting was clear (Arab-American University Clinic, Jenin, Palestine)
• Confirmed eligible sample
• Study design was not mentioned
• The sample size power was not calculated
• Age at evaluation of consequences was not mentioned
• Study only performed at the upper arch
• No controls
• Follow-up duration was not clear
6*
Teo et al., 2015 [17] • The objectives were clear
• The setting was clear (Dental Hospital, London, UK)
• The age was clear both at the time of extraction and evaluation of consequences
• Intraexaminer reliability was done
• The study design was not mentioned
• No sample size power calculation was performed
• Retrospective study design
14**
  1. Notes: *Scores from 1 to 7 (weak strength); **scores from 8 to 15 (moderate strength)
  2. Abbreviation: STROBE Strengthening the Reporting of Observational Studies in Epidemiology
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