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- Journal of Minimum Intervention in Dentistry
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- Volume 5, Issue 1, 2012
Journal of Minimum Intervention in Dentistry - Volume 5, Issue 1, 2012
Volume 5, Issue 1, 2012
Source: Journal of Minimum Intervention in Dentistry 5, pp 1 –3 (2012)More Less
Context: Quantitative systematic reviews need to consider clinical, methodological and statistical heterogeneity of trials or datasets from trials before combining their results in meta-analyses, as combining results from heterogeneous datasets and / or trials will lead to meaningless results and thus should be avoided. Potential statistical heterogeneity between trials / datasets that have been considered as being clinically / methodologically homogeneous is usually investigated using I2 - test and Cochrane Q statistics.
Problem: However, both, I2 - test and Cochrane Q statistics are tests with low statistical power, which gives even weaker results the smaller the number of trials / datasets is (n < 15).
Suggested solution: Therefore, statistical in-between-trial heterogeneity should be assessed using the point estimate together with its 95% Confidence interval of the I2 - test. Galbraith plots are to be used to identify outlying datasets / trials, which then should be further investigated for potential effect modifiers using regression analysis.
Source: Journal of Minimum Intervention in Dentistry 5, pp 4 –6 (2012)More Less
Context: Systematic reviews aim to assess precision and internal validity of the current clinical evidence. The precision and internal validity of clinical evidence is limited by the risk of biases, one of which is publication bias. Publication bias is created when trials, often with small sample size that have found negative or non-significant results are not being published and thus are not identified during systematic reviews as part of the of current clinical evidence. In that way, publication bias distorts precision and internal validity of clinical evidence. The extent of such distortion thus requires the assessment of publication bias risk as part of the systematic review methodology. Funnel plots and Egger's regression form one of the best currently available methods when assessing for publication bias risk.
Problem: However, funnel plot and Egger's regression have weak statistical power and its results may even be misleading when the number of included trials / datasets is small. They do not measure risk of publication bias directly but statistical in-between-trials heterogeneity in terms of their relation of sample size (SE) to effect size (lnRR). In that regard, the lack of published small trials is only one possible reason for any observed asymmetry. Other reasons are: (i) General in-between-trial heterogeneity and (ii) Methodological artifacts. Both will give positive results even in complete absence of publication bias risk.
Suggested solution: Therefore, funnel plot and Egger's regression need to be applied together with other considerations, which are presented in this research note, in order to obtain meaningful results.
Source: Journal of Minimum Intervention in Dentistry 5, pp 7 –10 (2012)More Less
The cavity design as dictated by GV Black had to be quite geometric with flat floors and walls, sharp internal line angles and some level of retentive undercuts to ensure stability in the restorative material. Now, in the light of current knowledge of the disease of caries, it is accepted that cavity design should be dictated entirely by the position and extent of the lesion itself.
Source: Journal of Minimum Intervention in Dentistry 5, pp 12 –18 (2012)More Less
In about 1900 GV Black evolved a classification for caries lesions and specified the design for the cavity that should be prepared to eliminate the lesion and hopefully avoid a recurrence. He was not aware of the modern concept of caries as a bacterial disease. He regarded the union between restoration and natural tooth structure as being a weak area very subject to plaque accumulation and therefore subject to recurrence of the disease. On these grounds he suggested that the margin should always be placed out on the smooth tooth surfaces where it could be easily kept clean. That is, he decided that extension for prevention was an essential parameter in cavity design. The profession has followed his instructions with only minor variations until this time.
Source: Journal of Minimum Intervention in Dentistry 5, pp 19 –22 (2012)More Less