Page 53 - Peri-implant health: the effect of implant design and surgical procedure on bone and soft tissue stability

HOW DO PERI-IMPLANT BIOLOGIC PARAMETERS CORRESPOND WITH IMPLANT SURVIVAL AND PERI-IMPLANTITIS? A CRITICAL REVIEW
were selected for full reading and only 41 withstood the quality check. This is a disappointingly low proportion for a topic with such a significant impact for patients, clinicians, and implants industry.
The included material in this paper is strongly skewed toward retrospective studies, with 6,246 retrospective and 3,411 prospective analyzed implants. One could address that this leads to a higher inclusion of lower quality data. The high amount of retrospective included implants is mainly caused by the large study of Derks and colleagues with 2,367 implants at baseline.83 However, the results showed a similar survival rate for retrospective and prospective analyzed implants, 97.2% and 96.2%, respectively, and in view of the large standard deviation, the difference in overall mean weighted bone loss between retrospective and prospective studies is not conclusive. Due to the large heterogeneity in the definition of peri‐implantitis, it was not possible to calculate whether there was a difference in the reported peri‐implantitis prevalence between retrospective and prospective analyzed implants.
Regarding the statistical analysis, it was opted to use the Pearson correlation coefficient. Although the justification of this correlation coefficient instead of the Spearman’s relation coefficient could be a point of debate when data are possibly not normally distributed, the distribution at the level of the separate studies is most often skewed, when reported, and the presence of outliers cannot be excluded. This results in the distinct difference in variability of the different studies and the unreliability of estimates of the standard deviation for the individual studies. To circumvent the problem of unreliable estimates of the standard deviation, weighting by sample size was performed. At the level of the studies, though, no real outliers are present. The Pearson correlation coefficient is a measure of linear approximation, and the Spearman correlation coefficient is a measure of association that is not immediately translates to linearity. In view of the attempt to demonstrate the absence or presence of linear relations, the Pearson correlation was chosen together with the graphical representation to visually assess the relation described by the coefficient. Testing of the correlation coefficient would have required normality at both levels and reliable estimates of the within variability and between study variability. It is clear that, these requirements were not met, and therefore, the presented results are exploratory and descriptive in nature.
51
3