Direct (CCD or CMOS) and indirect (storage phosphor plate) digital systems for intra-oral radiography are now commonplace not only in dental research but also across diverse research fields. A recent article investigated the image quality and radiation dose of the two systems. This paper gives a critical review of the journal dealing with issues like the originality of the research, factual errors, lucidity in writing, statistical analysis, a test of hypothesis, evidence interpretation, and acknowledge of previous work among other research issues.
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This research was scientifically adequate and of adequate originality. Scientifically sound research requires that researchers review the available literature on the subject; 5 is something that these researchers did satisfactorily. In the course of the literature review, these researchers studied previous studies and compared their findings with what had already been established. For instance, they reported that a previous study in 2003 by de Almeida et al showed that the CCD system was found to be better than the PSP system. This aspect proves this research scientifically sound and gives it originality given the fact that the results obtained differed or agreed with other previous studies.
The article contained some factual errors. For instance, the expected number of images to be obtained was not reached and the reason given to this is that there was not sufficient time to collect the projected numbers of mandibular premolars and incisors. The fact that the planned images could not be obtained shows there was a change of plan in the whole study to fit the available samples. Again, the researchers could not ascertain the statistical significance of repeat periapical radiographs due to the restricted number of patients and this presents a potential source of factual error. Finally, analyzing each image within its own software and allowing observers to manipulate images in their own software may lead to bias hence a factual error.
The lucidity of the paper is relative. In some areas, it qualifies in terms of limpidity but in others, it underscores. For instance, concerning the modality used to analyze the images, the reader cannot tell clearly, the methods used because all of them are written as propositions. Nevertheless, most of the parts of the paper are lucidly written. The researchers have not omitted any key facts in this paper. Most of the facts about the two systems have been included ranging from how the two systems works, reviewing past research on the same and use of accredited methods like comparing radiographs with credible grading systems like National Radiological Protection Board (NRPB) system for grading image quality.
The sample size used was adequate. Sample-size problems are context-dependent. For example, how important it is to increase the sample size to account for such uncertainty depends on practical and ethical criteria. Moreover, sample size is not always the main issue; it is only one aspect of the quality of a study design. In this case, the sample used met the practical criteria, which called for repeat radiographs. This takes into account the fact that some individuals could not tolerate the sensor and holder coupled with realization that some images tested non-diagnostic and these subjects could not stand repeated exposure. This justifies the preferably large number of sample that the researchers employed in this case.
The study was not adequately controlled. The only control used is from literature review and this does not offer strong control experiment. They relied mostly on what had been done in the past to judge performance of these two systems. Moreover, most of the studies done in the past were in vitro conditions and sometimes this does not measure up to in vivo experiments. For instance, earlier research by de Almeida et al in 2003 showed that CCD system was more effective than PSP system; however, it emerged that these studies were carried out in vitro.
Systematic bias was not avoided but it was minimized. By allowing observers to manipulate objects to their own convenience, they did not avoid that systematic bias. However, they minimized it by masking the borders of active areas of both CCD and PSP systems. They also blinded all the observers to the identity of the imaging systems. It is important to note that this is one of the blurred areas lacking lucidity in the report making it difficult to determine precisely which method was used. This may be deliberate or mistakenly; it is difficult to tell the motive behind it.
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The statistical analysis was appropriate. Chi-squared tests are commonly used to analyze statistical data and this is what this group used. 1 df trend component is the standard in analyzing 3-point ordinal radiographic quality score. They used quadratic weighted kappa for the 3-point scale, an appropriate method for such assessments. In determining which radiography required a repeat, they used Scott’s pi. These are tested and proved statistical methods that are appropriate in analyzing statistical data.
The study tested author’s hypothesis and determined that The PSP Vista scan system produced significantly higher quality intra-oral periapical images compared with the CCD Sidexis system. This was the aim as the author had concluded the same after reading several previous studies on the same. The team interpreted the evidence satisfactorily by use of tables and giving detailed discussion of what happened in the study. They started by explaining how they collected, processed, and analyzed data with reference to established methods giving account of what took place systematically. This systematic analysis of events gives a satisfactory interpretation of the evidence obtained.
The data obtained was sufficient in quality to justify author’s conclusion. It is clear that PSP systems attained the targets stipulated by NRPB. That is, PSP scored 71% excellent and 6% unsatisfactory compared to standards of ≥70 excellent and ≤10 unsatisfactory. On the other hand, CCD fell short of these targets; therefore, this data was sufficient for the author to conclude that PSP systems are better than CCD system.
The author duly recognized previous work. For instance, there was a comparison of what de Almeida et al had done on the same subject. The author also considered Borg Grondahl and Grondahl HG’s work in 1997 where they had similar results on the same issue. The abstract does not give the whole paper in miniature; actually, the title of the article was taken as the abstract. Patients benefit largely from this study because they now know that PSP systems functions better at low exposures and short exposure period to give right diagnostic results than CCD.
This article was scientifically adequate and original with few factual errors portraying lucidity at some points and unclear information at others. Without omitting any significant facts, the author used adequate sample materials even though there was lack of controls. However, the author minimized systematic errors and gave a coherent statistical analysis coupled with satisfactory interpretation of evidence. Acknowledging previous works, the author had sufficient quality data to justify the conclusion made.
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