Goodchild Jason H, Donaldson Mark
Director of Clinical Affairs, Premier Dental Products Co., Plymouth Meeting, Pennsylvania; Associate Clinical Professor, Department of Diagnostic Sciences, Creighton University School of Dentistry, Omaha Nebraska; Adjunct Assistant Professor, Division of Oral Diagnosis, Department of Diagnostic Sciences, Rutgers School of Dental Medicine, New Brunswick, New Jersey.
Associate Principal, Vizient Pharmacy Advisory Solutions, Irving, Texas; Clinical Professor, School of Pharmacy, University of Montana, Missoula, Montana; Clinical Assistant Professor, School of Dentistry, Oregon Health and Sciences University, Portland, Oregon.
Compend Contin Educ Dent. 2019 Jul/Aug;40(7):e1-e10.
Alkalinization or buffering of dental local anesthetics to raise the pH of these acidic solutions is a well-documented technique that results in clinical benefits such as decreased injection pain, reduced onset time, and the need for less overall volume of local anesthesia.
In a previous study, two options available for buffering local anesthetics in dentistry were compared, one using the Onpharma® mixing system (Onpharma), and the other by hand mixing with 8.4% sodium bicarbonate using a "remove and replace" technique. The results of that study showed no statistically significant difference in buffering outcomes between the two methods. This follow-up in vitro study introduces and examines a less complex, direct injection, chairside hand-mixing approach using four commercially available dental local anesthetic preparations.
The authors prepared multiple buffered samples of four different commercially available local anesthetic solutions. The buffered samples were mixed to 9:1, 19:1, and 18:1 ratios (local anesthetic to 8.4% sodium bicarbonate). Sample pH was recorded using a pH meter. Two samples of each local anesthetic at each ratio were prepared and sequentially pH tested. The pH was recorded via the same pH meter, which was cleaned between each test.
The pH change between unbuffered solutions and all buffered samples was statistically different (P < .01, CI 99%). There was no final pH difference between the 9:1 and 19:1, and 19:1 and 18:1 buffering ratios (P > .01); however, a statistical difference was seen between the final pHs of the solutions resulting from the 9:1 and 18:1 buffering ratios (P = .006, CI 99%). After correction for multiple comparisons, the difference between the 9:1 and 18:1 ratio was marginally significant (P = .048).
Each of the buffering ratios tested can be used to alkalinize dental local anesthetic solutions. For practical purposes, a direct injection chairside of 0.1 mL of 8.4% sodium bicarbonate into any of the four local anesthetics tested is easy, simple, and safe compared to the more complex remove and replace method. Further studies are needed to evaluate if a clinically significant difference exists between the 9:1, 19:1, and 18:1 ratio solutions.
The potential benefits of buffering local anesthetic solutions prior to injection, such as decreased injection pain, faster onset, and greater depth of anesthesia, may be particularly advantageous in patients who have difficulty achieving profound anesthesia for clinical dentistry, and for anesthetizing infected areas. Dentists can effectively buffer local anesthetic preparations using commercially available mixing systems or by utilizing a hand-mixing technique. Rather than using a remove and replace technique, practitioners may consider a direct injection technique, adding 0.1 mL of 8.4% sodium bicarbonate directly into any local anesthetic cartridge regardless of local anesthetic concentration.
将牙科局部麻醉剂碱化或缓冲以提高这些酸性溶液的pH值是一种有充分文献记载的技术，可带来临床益处，如减轻注射疼痛、缩短起效时间以及减少局部麻醉剂的总体用量。
在之前的一项研究中，比较了牙科局部麻醉剂缓冲的两种可用方法，一种使用Onpharma®混合系统（Onpharma），另一种是使用“抽取并替换”技术与8.4%碳酸氢钠手工混合。该研究结果显示两种方法在缓冲效果上无统计学显著差异。这项后续的体外研究引入并检验了一种使用四种市售牙科局部麻醉剂制剂的不太复杂的直接注射、椅旁手工混合方法。
作者制备了四种不同市售局部麻醉剂溶液的多个缓冲样本。将缓冲样本按9:1、19:1和18:1的比例（局部麻醉剂与8.4%碳酸氢钠）混合。使用pH计记录样本的pH值。每种局部麻醉剂在每个比例下制备两个样本，并依次进行pH测试。通过同一台pH计记录pH值，每次测试之间对pH计进行清洁。
未缓冲溶液与所有缓冲样本之间的pH变化具有统计学差异（P <.01，99%置信区间）。9:1与19:1以及19:1与18:1的缓冲比例之间最终pH无差异（P >.01）；然而，9:1和18:1缓冲比例所得溶液的最终pH之间存在统计学差异（P =.006，99%置信区间）。在进行多重比较校正后，9:1与18:1比例之间的差异边缘显著（P =.048）。
所测试的每种缓冲比例均可用于使牙科局部麻醉剂溶液碱化。出于实际目的，与更复杂的抽取并替换方法相比，在椅旁将0.1 mL 8.4%碳酸氢钠直接注射到所测试的四种局部麻醉剂中的任何一种中既简便又安全。需要进一步研究以评估9:1、19:1和18:1比例溶液之间是否存在临床显著差异。
在注射前缓冲局部麻醉剂溶液的潜在益处，如减轻注射疼痛、更快起效和更深的麻醉深度，对于临床牙科难以实现深度麻醉的患者以及麻醉感染区域可能特别有利。牙医可以使用市售混合系统或通过手工混合技术有效地缓冲局部麻醉剂制剂。从业者可考虑直接注射技术，而不是使用抽取并替换技术，直接将0.1 mL 8.4%碳酸氢钠添加到任何局部麻醉剂药筒中，无论局部麻醉剂浓度如何。
