The effect of adjusting the pH of local anaesthetics in dentistry: a systematic review and meta‐analysis

Abstract

The acidic nature of commercial local anaesthetics (LAs) can cause pain during infiltration and delay the onset of anaesthesia. It is suggested that adjusting the pH of anaesthetic agents could minimize these effects. This systematic review aimed to evaluate the efficacy of buffered LAs in reducing infiltration pain and onset time during dental procedures. MEDLINE, Embase, Scopus and Scielo databases were searched up to April 2017. Randomized controlled trials comparing buffered and unbuffered LAs for intraoral injections were included. Risk of bias was assessed using the Cochrane Collaboration tool. Data upon injection pain and onset time were pooled in a random-effects model. Subgroup analyses compared normal and inflamed tissues, and terminal infiltrations and inferior alveolar nerve (IAN) blocks. Meta-regressions were performed to explain heterogeneity. Fourteen articles were included in this review. Lidocaine with epinephrine was the most used anaesthetic combination. Nonlidocaine studies (n = 2) were not pooled in the meta-analysis. Buffered lidocaine did not result in less pain during intraoral injections: mean difference -6.4 (95% CI -12.81 to 0.01) units in a 0-100 scale. Alkalinized lidocaine did not reduce the onset time in normal tissues when terminal infiltration techniques were used, but resulted in a more rapid onset for IAN blocks (-1.26 min) and in inflamed tissues (-1.37 min); however, this change may not be clinically relevant, considering the time required to prepare the buffered agent. Studies performed using other anaesthetic salts did not show robust and clinically significant results in favour of alkalinization.

Conditioned place preference reveals ongoing pain in calves 3 weeks after disbudding

“…However, the cream was used for both lidocaine and saline injections and so cannot explain the sham calves' aversion to lidocaine. In humans, buffering lidocaine decreases the pain of injection for non-oral procedures, but does not eliminate it 27,28 . A strategy that we did not consider was warming lidocaine to body temperature, as this has been shown to decrease pain in humans, compared to when it is given at room temperature 29 .…”

Efficacy of sodium bicarbonate buffered versus non-buffered lidocaine with epinephrine in inferior alveolar nerve block: A meta-analysis

“…A recent systematic review [ 32 ] has been published in 2018, and has a different PICO question compared to the current systematic review. The aim of the previous systematic review was to investigate the efficacy of buffered local anesthetics in reducing infiltration pain and anesthesia onset time in dentistry.…”

Calcium hydroxide intracanal medication effects on pain and flare-up: a systematic review and meta-analysis

“…Very-low quality evidence revealed a similarity in the efficacy of CH and CHX alone or when mixed with CH in pain-risk prevention ( Figure 3A-3C , Supplementary Tables 6 and 7 ) [ 12 21 29 ], while moderate-quality evidence showed that CHX may be more beneficial in reducing pain severity either alone or when added to CH [ 11 ] ( Supplementary Tables 6 and 7 ); such reduction in severity, however, may not be that clinically significant being less than 15 points on a 0–100 pain scale [ 32 ]. CHX was also effective in reducing flare-up risk than CH by around 75% (RR pooled , 0.26; 95% CI, 0.07 to 0.99) in a population with the majority of patients being diabetic; evidence, however, is of very low quality.…”

“…Substantial heterogeneity has been recorded in some instances of data synthesis with pain incidence ( Figure 3A ) or pain intensity ( Figure 4C and 4E ). The main concern with pain studies is the tool used to measure pain since it can introduce a source of clinical heterogeneity among studies [ 19 32 ] where the number of response points within a scale is important since a small number requires a larger change in pain before scores change. In contrast, a large number can be useless as it can have more levels of discrimination than most patients use [ 32 38 ].…”

“…contrast, a large number can be useless as it can have more levels of discrimination than most patients use [32,38]. Differences in the included populations in studies can also be a source of heterogeneity among pain-intensity studies comparing CH with CS/AB ( Figure 4C and 4E), and pain-incidence studies comparing CH with CHX ( Figure 3A).…”