Critical Appraisal Of Endodontic Working Length Measurement Study

What effects do they have on choosing the treatment, why and how will they influence your final choice of treatment.

Clear research question

The ability to successfully appraise scientific research studies is an important skill in clinical practice as it enables clinicians to apply the results of the scientific studies to individual patient’s circumstances, thereby enabling informed decision making (Young & Solomon 2009). The current paper seeks to examine the weaknesses and strengths of the research study ‘Endondontic Working Length Measurement with Preexisting Cone-Beam Computed Tomography Scanning: A Prospective, Controlled Clinical Study’ by Jeger, et al (2012) so as to determine the validity, applicability, and usefulness of the research findings in clinical practice. The critical appraisal will involve an evaluation of the utilized research design as well as a close assessment of the design’s major methodological characteristics to determine its appropriateness for the research question. Additionally, as suggested by Young & Solomon (2009), the appropriateness of the statistical methods utilized in analysis and interpretation and relevance of research study to medicine are also important considerations in carrying out a critical appraisal, and thus will be evaluated.

There are a number of critical appraisal tools that have been developed. For those developed by Critical Appraisal Skills Programme (CASP), the appropiate appraisal tool depends on the type of study design utilized in the research study (Jahanzeb, n.d ). As Students 4 Best Evidence (2013) states,  CASP checklist is composed of questions which help individuals appraise research literature without it providing an overall score on validy or reliability of the study. The individuals conducting the appraisal are expected to conclude on the validity, reliability and usefulness of the literature.

The critical appraisal tool for diagnostic study provided by CASP is comprised of three broad questions which seeks to determine the results, whether the study’s results are valid and whether the study’s results are applicable to individual patients or population (CASP, 2017). The three broad questions are then broken down into twelve questions, which will guide the critical appraisal and help in determining the methodological quality of Jeger, et al (2012)’s study as well as its validity, reliability and applicability in evidence-based medicine.

Clear question for the study

Jeger, et al’s research question was “to analyze endodontic working length measurements in preexisting cone-beam computed tomography (CBCT) scans and to compare them with clinical root canal length determination by using an electronic apex locator (EAL)”. This research question was clearly focused as it included themes such as population, test, setting and outcome. In the study, a 40 anterior teeth were included, a significantly small sample size that did not even include posterior teeth.

Performance of diagnostic test

Performance of Diagnostic test and reference standard

All patients had preexisting CBCT scans, and EAL was performed on all the patients, ensuring that each patient had undegone both diagnostic test and reference standard test. The criterion of inclusion involved consistency in EAL measurements, which ensured CBCT measurement was done on all teeth, including those with metallic reconstruction, a teeth filling process.  Inclusion of teeth with metallic constructions may have led to inaccuracy in measurements.  Exclusion of molars, premolars and other teeth that did not appear completely in CBCT scan, that had radiographic artifacts, and that underwent edge modifications after CBCT scanning was done. However  only patients who had preexisting CBCT scans were included in the study, limiting the patients’wide spectrum. Similarly, exclusion of molars and premolars was unreasonable as it further limited the wide spectrum of patients. Consequently, the validity of the study may have been reduced.

comparison with appopriate reference standard

The accuracy of any diagnostic test relies on comparing it with a gold or reference standard (Manikandan & Dorairajan  2011). In the research study by Jeger, et al (2012), root canal length was measured using Electronic Apex Locator (EAL) as the gold standard and a comparison was made with root canal measurements using CBCT scans, the investigation under trial. EAL is a conventional measurement tool whose usage and validity has been well documented in literature (Razavian, Mosleh, Khazaei, & Vali, 2014), and therefore qualifies to be a gold standard test. Additionally this was backed up by PA radiograph, which is again a gold standard (Dixon, 2006). Also, both the reference and diagnostic tests were performed on all included partcipants of the study. This ensures ascertaining of the reference standard independent of the results of diagnostic test(Wang, n.d ).

Test results influenced by reference standard results?

Validity of the results of a study are also determined by whether individuals conducting or interpreting the test under investigation were blinded to results of the gold or reference standard (Manikandan & Dorairajan, 2011). Blinding ensures expectation bias is avoided (Bland, 2010). In the study by Jeger, et al (2012), the CBCT and EAL measurements  were independently performed and blinding was done where the investigator evaluating measurements using EAL was blinded to the results of the CBCT scans(and vice versa).The individuals involved in pilot study were not included, avoiding bias. Additionally, conduction and evaluation of CBCT scans was performed by a qualified professional who did not take part in any endodontic treatment step, and was done before measurements using EAL, an indication that blinding was done. In this regard, there is high likelihood that results of CBCT scans were not influenced by those of EAL, the reference test and bias was significantly reduced. Moreover, to improve validity of the study, CBCT scans were evaluated two more times.

Comparison with appropriate reference standard

Detailed methods description?

Determination of whether a sufficient description of the methods and procedure to perform the test under investigation is an important indicator of the validity of the results (CASP, 2017).  As Manikandan & Dorairajan, (2011) states, this is  important to enable replication, especially if the authors suggest that the test they investigated is useful and its usage is recommended. In the research study by Jeger, et al (2012), usefulness of CBCT scans is declared and the authors recommends the test for measurements of endodontic working length. A sufficient description of the methodological protocol for using limited CBCT scans in measurements of endodontic working length is outlined in the ‘methods’ section where the step-by-step procedure for evaluation of CBCT images is described, the specialized software utilized in measuring and alligning procedures is given and the technical imaging modality is specified. Thus, it is possible for other investigators to replicate and utilize the study.

What are the results?

The correlation between a reference test and a diagnostic test is represented by various statistical tools. The most common ones include sensitivity, specificity, and likelihood ratios. Sensitivity and specificity are utilized in scientific studies more than likelihood ratios, although the latter has been found to be more effective in determining a diagnostic tool’s efficiency (Chien, Malhotra, & Bhandari, 2011). With regard to Jeger, et al’s study, neither sensitivity, specificity nor likelihood ratios could be calculated to determine the effectiveness of CBCT scans as a diagnostic tool. Results were presented in form of pearson correlation coefficient , mean discrepacy and range. Therefore, the study left out important diagnostic parameters that would be of help to medical professionals and would help validate the study.

Surelity of results

 Jeger, et al presented their results with range and confidence intervals. Range and confidence interval use is an indication of the study’s precision (Jaeschke, Guyatt, & Sackett, 1994).

Applicability  of test results to my Patients

The results of any study can only be applied to certain patients if the participants of the study have similar prognostic characteristics. In Jeger et al, the study participants were patients who had previously undergone Cone-Beam Computed Tomography scans. Since Jeger, et al incorporated both sexes and individuals of ages ranging from 18 to 80 years, the results are applicable to patients in my healthcare setting who have preexisting CBCT scans. However, this inclusion criterion may exclude some patients who are yet to undergo CBCT scanning for the first time.

Results presentation

Applicability of Test

Most radiologists can interpret CBCT scans, and thus can be applied in my healthcare setting. However, since CBCT is not frequently recommended unless regular dental x-rays have proven to be insufficient, equipments to provide CBCT scan may currently be limited, reducing the test’s applicability.

Importance of outcomes  and Impacts of using the test to patients

Application of CBCT scans in root canal measurements may lead to a positive change in dental healthcare setting. This is because CBCT is capable of providing dental professionals with 3-dimensional dental structured images of high quality due to its high spatial resolution (Michetti, Maret, Mallet, & Diemer, 2010).  Also, utilization of the test may contribute positively to the well-being of patients by a successful endondotic treatment after an effective and accurate diagnosis. However, the detrimental effects of exposure to the high radiation during scanning may reduce the applicability of this test.

Conclusion:

Therefore, Jeger, et al (2012) , although with a number of shortcomings in its design and presentation of results, has addressed most of the recommended guidelines of a valid, high quality study by CASP checklist of a diagnostic study. In general, the study results are valid and the test is applicable to patients in my dental setting. However, the study failed to present its results using statistical tools recommended for diagnostic studies. In this regard, the study can be of use in enhancing decision making by dentists regarding endodontic treatment.

References:

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Chien, T., Malhotra, R., & Bhandari, M. (2011). The 3-Min Appraisal of a Diagnostic Test . Indian Journal of Orthopaedics , vol 45, no 5, pp 389-391.

Critical Appraisal Skills Programme, CASP. (2017). 12 Questions to Help you Make Sense of a Diagnostic Test Study .

Dixon, B. E. (2006). Periapical Radiography. Available at https://v5.books.elsevier.com/bookscat/samples/9780443102134/9780443102134.pdf [Accessed May 21, 2017]

Jaeschke, R., Guyatt, G., & Sackett, D. (1994). User's Guide to the Medical Literature: How to Use an Article about Diagnostic Test. Jama , vol271, pp 389-391.

Jahanzeb, S. (n.d ). Lecturer in Dental Education. BPP University.

Jeger, B.J., Janner S., Bornstein M.M., & Lussi, A., (2012), Endondontic Working Length Measurement with Preexisting Cone-Beam Computed Tomography Scanning: A Prospective, Controlled Clinical Study. JOE. vol 38, no 7, pp 884-888.

Manikandan, R., & Dorairajan, L. N. (2011). How to Appraise a Diagnostic Test. Indian Journal of Urology , vol 27, no 4, pp 413-419.

Michetti, J., Maret, D., Mallet, J.-P., & Diemer, F. (2010). Validation of Cone BeamComputed Tomography as a Tool to Explore Root Canal Anatomy . JOE , vol 36, no 7, pp 1187-1190.

Razavian, H., Mosleh, H., Khazaei, S., & Vali, A. (2014). Electronic apex locator: A comprehensive literature review — Part II: Effect of different clinical and technical conditions on electronic apex locator's accuracy. Dent Hypotheses , vol 5 , no 4, pp 133-141.

Students 4 Best Evidence. (2013). CASP Diagnostic Test Study Appraisal . Available at: <https://www.students4bestevidence.net/casp-diagnostic-test-study-appraisal/> [Accessed May 18,2017]

Wang, M.-C. (n.d ). Critical Appraisal of Diagnostic Study .Available at <https://media.wix.com/ugd/dded87_3815f02af1b34c21b8c3b2b5020024c3.pdf> [Accessed May 18,2017]

Young, J. M., & Solomon, M. J. (2009). How to Critically Appraise an Article. Nat Clin Pract Gastroenterol Hepatol. ; , vol 6, pp 282-291.