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.

牙周治疗效果的评估基于仔细定义的临床参数，包括减少发红、肿胀、探诊出血和牙周袋深度 (PPD)，以及临床附着水平 (CAL) 和牙龈退缩量的增加. CAL 评估非常重要，因为它是临床评估疾病稳定性或进展的唯一方法。

要了解科学论文中的 CAL 测量实际上是如何进行的，取决于作者提供的描述。阅读Journal of Clinical Periodontology ( JCP ) 论文中的材料和方法部分) 在过去 5 年中，对如何进行 CAL 测量的描述似乎存在很大差异。在一些论文中，根本没有提到 CAL 方法论；在一些论文中，CAL 评估是基于使用袋深度和正/负牙龈退缩的计算；然而，在大多数研究中，只提及 CAL 评估而没有任何进一步的信息。如果在非手术治疗之前和之后评估除了积极之外还有消极的衰退，就可以计算牙龈深度减少的程度是由于牙龈退缩还是 CAL 增加，这对临床医生来说是重要的信息。此外，它可能有助于估计数据的可靠性，从而对文献产生积极影响。最后一个在以下示例中进行了说明。

在过去十年中，人们越来越关注营养在牙周病中的作用。最近， JCP发表了一篇关于非手术治疗和 omega-3 脂肪酸摄入对牙周病患者干预效果的系统评价（Heo 等，  2022）。作者建议，补充摄入 omega-3 脂肪酸对治疗牙周炎可能有积极作用。就测试和对照之间的 CAL 增益差异而言，Deore 等人发现 3 个月研究中的最大差异。( 2014 ) 以及 Elgendy 和 Kazem 为期 6 个月的研究 ( 2018). 这两项研究的 PPD 和 CAL 结果如表 1 所示。然而，在分析该表中的数据时，不容易看出 PPD 和 CAL 与牙骨质-牙釉质交界位置的关系。因此，绘制了使这种关系可见的图（图 1）。通过查看这些图，可以很容易地看出，在治疗后获得的 PPD 减少在测试组和对照组中已完全通过临床附着的增加实现，而没有牙龈退缩的任何贡献。这与非手术牙周治疗后 PPD 减少（两项研究中的对照组）是牙龈退缩和临床附着增加相结合的共同理解相冲突。因此，将这些 CAL 数据纳入审查可能会受到质疑。

总之，建议在JCP的作者须知部分添加一句话，说明当临床研究中包含 CAL 时，他们应该清楚地描述如何获得 CAL 测量值，同时考虑到位置牙龈边缘相对于牙骨质牙釉质交界处或固定参考点的位置。