Buffered Versus Non-Buffered Dental Local Anesthetics: A Systematic Review and Meta-analysis of Within-Subject Clinical Studies

Buffered Versus Non-Buffered Dental Local Anesthetics: A Systematic Review and Meta-analysis of Within-Subject Clinical StudiesABSTRACTBackground:Buffering dental local anesthetics (LAs) with sodium bicarbonate has been proposed to reduce injection pain and improve anesthetic performance; however, clinical evidence remains inconsistent and methodologically heterogeneous.Objectives:To evaluate the effects of buffered versus non-buffered dental LAs on anesthetic success, pain, onset time, and duration, restricting inclusion to within-subject study designs and exploring injection technique and buffering ratio as potential effect modifiers.Methods:A PRISMA-compliant systematic review and pairwise meta-analysis was conducted. Split-mouth and cross-over studies in adult patients receiving dental LAs were included. Primary outcomes were anesthetic success and duration; secondary outcomes were pain during puncture and injection, onset time, and adverse effects. Random-effects models were applied, with subgroup analyses and meta-regressions according to injection technique.Results:Fifteen studies (518 participants; 1,105 injections) were included, with 14 contributing to quantitative synthesis. Overall anesthetic success did not differ between buffered and non-buffered LAs (OR = 1.00; 95% CI 0.84–1.19; I² = 0%). Buffered solutions significantly reduced pain during puncture (MD = −0.90; p = 0.037) and showed technique-dependent effects for pain during injection and anesthesia duration, particularly for inferior alveolar nerve block (IANB). No consistent benefit was observed for onset time. Substantial heterogeneity was present for several outcomes.Conclusions:Buffering dental LAs does not improve anesthetic success but provides clinically relevant comfort benefits, particularly by reducing puncture-related pain and in selected injection techniques. Buffering should be regarded primarily as a comfort-oriented strategy rather than an efficacy-enhancing intervention.

《缓冲与非缓冲牙科局部麻醉剂：一项针对受试者内临床研究的系统评价与荟萃分析》摘要
背景：将碳酸氢钠（sodium bicarbonate）与牙科局部麻醉剂（dental local anesthetics，LAs）混合以缓冲其pH值，被认为可降低注射疼痛并改善麻醉效果，但目前临床证据仍存在分歧，且方法学异质性较高。
目的：评估缓冲与非缓冲牙科局部麻醉剂在麻醉成功率、疼痛程度、起效时间与持续时间方面的差异，仅纳入受试者内研究设计，并探讨注射技术与缓冲比例作为潜在的效应调节因子。
方法：本研究遵循PRISMA声明开展系统评价与成对荟萃分析。纳入接受牙科局部麻醉的成年患者的分颌研究与交叉研究。主要结局指标为麻醉成功率与麻醉持续时间；次要结局指标为穿刺与注射过程中的疼痛程度、起效时间及不良反应。采用随机效应模型进行分析，并依据注射技术开展亚组分析与荟萃回归分析。
结果：共纳入15项研究（含518名受试者，1105次注射），其中14项研究可用于定量合成分析。总体麻醉成功率在缓冲与非缓冲麻醉剂间无显著差异（比值比OR=1.00；95%置信区间CI：0.84~1.19；异质性指数I²=0%）。缓冲液可显著降低穿刺相关疼痛（均数差MD=-0.90；p=0.037），且在注射疼痛与麻醉持续时间方面表现出技术依赖性效应，尤其在下牙槽神经阻滞麻醉（inferior alveolar nerve block，IANB）中更为明显。未观察到起效时间存在一致获益。多项结局指标存在显著异质性。
结论：缓冲牙科局部麻醉剂并不能提升麻醉成功率，但可带来具有临床意义的舒适度获益，尤其是在降低穿刺相关疼痛以及特定注射技术场景中。缓冲处理应主要被视为一种以提升舒适度为目标的策略，而非增强麻醉效果的干预手段。