LAUSR

Dear Editor Evaluation of the effect of periodontal treatment is based on carefully defined clinical parameters in terms of reduction of redness, swelling, bleeding on probing and periodontal pocket depth (PPD), as well as gains in clinical attachment level (CAL) and amount of gingival recession. CAL assessment is important especially because it is the only method to clinically assess disease stability or progression. To understand how CAL measurements in scientific papers are actually performed, one is dependent on descriptions provided by the authors. Reading the Material and Methods sections in papers of the Journal of Clinical Periodontology (JCP) over the last 5 years, it appears that there is great variability in descriptions of how CAL measurements were taken. In some papers, CAL methodology is not mentioned at all; in a few papers, CAL assessment is based on calculations using pocket depth and positive/negative gingival recessions; however, in most studies, CAL assessment is mentioned without any further information. If besides positive also negative recessions are assessed before and after non-surgical treatment, it can be calculated to what extent pocket depth reduction was due to gingival recession or to CAL gain, which is important information for clinicians. In addition, it may help estimate the reliability of data and thus positively impact the literature. This last is illustrated in the following example. During the last decade, there has been an increasing interest in the role of nutrition in periodontal disease. Recently, a systematic review on the interventional effect of non-surgical treatment and omega-3 fatty acids intake in patients with periodontal diseases was published in the JCP (Heo et al., 2022). The authors suggested that supplemental intake of omega-3 fatty acids for the treatment of periodontitis may have a positive effect. In terms of CAL gain differences between test and control, the greatest difference in the 3-month studies was found by Deore et al. (2014) and in the 6-month study by Elgendy and Kazem (2018). The results regarding PPD and CAL of these two studies are presented in Table 1. When analysing the data in this table, however, it is not easy to see the relationship of PPD and CAL with the position of the cemento-enamel junction. Therefore, drawings were made to make this relation visible (Figure 1). By looking at these drawings, it can be easily seen that the obtained PPD reduction after treatment in both test and control groups has been fully realized by gain of clinical attachment without any contribution of gingival recession. This conflicts with the common understanding that PPD reduction following non-surgical periodontal treatment (the control groups in the two studies) results from a combination of gingival recession and gain in clinical attachment. Therefore, inclusion of these CAL data in the review may be questioned. In conclusion, it is suggested that in the Instructions for Authors section of the JCP, a sentence may be added stating that when CAL is included in clinical studies, they should provide a clear description of how CAL measurements were obtained, taking into account the location of the gingival margin relative to the cemento-enamel junction or a fixed reference point.