Lee Wanki, Jo Jung Hwan, Park Young-Seok, Park Ji Woon
Center for Future Dentistry, School of Dentistry, Seoul National University, Seoul, Republic of Korea.
Dental Research Institute, Seoul National University, 101, Daehak-ro, Jongno-gu, Seoul, 03080, Republic of Korea.
Sci Rep. 2025 Feb 6;15(1):4467. doi: 10.1038/s41598-024-83177-x.
The cysteine challenge test is a reliable and efficient method for halitosis diagnosis and assessing treatment effectiveness by measuring the capacity to produce hydrogen sulfide. However, several aspects related to the test including evaluation timing and total duration following cysteine loading has not been investigated in-depth and a standardized protocol is yet to be established. This observational study compared concentrations of volatile sulfur compounds (VSCs) following cysteine challenge at various time points based on different measurement tools to investigate clinical factors influencing the results. Cysteine challenge (rinsing for 30 s with 5 mL of 6 mM L-cysteine solution) was applied in 100 healthy subjects. VSC concentration of oral cavity gas was analyzed with standard and portable gas chromatography (GC) at 5 time points (before, immediately, 10, 20, and 30 min after cysteine challenge). The Community Periodontal Index of Treatment Needs (CPITN), Winkel's Tongue Coating Index, and salivary flow rate were assessed. VSC levels significantly increased immediately after cysteine challenge (p < 0.001 for hydrogen sulfide, p < 0.001 with standard GC and p < 0.05 with portable GC for methyl mercaptan). Levels significantly decreased at 10 min after cysteine challenge except for methyl mercaptan measured with standard GC (p < 0.001). Subjects still showing VSCs 20 min after cysteine challenge was less than 15% of those initially positive. The amount of tongue coating showed significant association with methyl mercaptan levels immediately after (β = 0.202, p = 0.049) and 10 min following (β = 0.207, p = 0.045) cysteine challenge and CPITN showed acceptable discriminative power for persistent detection of methyl mercaptan (cut-off = 1.5, AUC = 0.668). Cysteine challenge may enhance the possibility of detecting VSCs during halitosis diagnosis. Standardized test protocols should address measurement timing, tools used, and tongue coating levels as clinical factors influencing VSC detection.
半胱氨酸激发试验是一种可靠且有效的口臭诊断及评估治疗效果的方法，它通过测量产生硫化氢的能力来实现。然而，与该试验相关的几个方面，包括评估时间和半胱氨酸负荷后的总时长，尚未得到深入研究，且尚未建立标准化方案。这项观察性研究基于不同测量工具，比较了半胱氨酸激发后不同时间点的挥发性硫化物（VSCs）浓度，以探究影响结果的临床因素。对100名健康受试者进行半胱氨酸激发试验（用5毫升6毫摩尔/升的L-半胱氨酸溶液漱口30秒）。在5个时间点（半胱氨酸激发前、激发后即刻、10分钟、20分钟和30分钟），使用标准气相色谱仪（GC）和便携式气相色谱仪分析口腔气体中的VSC浓度。评估治疗需要社区牙周指数（CPITN）、温克尔舌苔指数和唾液流速。半胱氨酸激发后即刻，VSC水平显著升高（硫化氢p < 0.001，标准GC检测甲硫醇时p < 0.001，便携式GC检测甲硫醇时p < 0.05）。除标准GC测量的甲硫醇外，半胱氨酸激发后10分钟时水平显著下降（p < 0.001）。半胱氨酸激发后20分钟仍显示有VSCs的受试者不到最初呈阳性者的15%。舌苔量在半胱氨酸激发后即刻（β = 0.202，p = 0.049）和10分钟后（β = 0.207，p = 0.045）与甲硫醇水平呈显著相关，CPITN对持续检测甲硫醇具有可接受的判别能力（截断值 = 1.5，曲线下面积 = 0.668）。半胱氨酸激发试验可能会增加口臭诊断过程中检测VSCs的可能性。标准化试验方案应考虑测量时间、所用工具以及舌苔量等影响VSC检测的临床因素。
