Successful local anaesthesia is required for the prevention of pain for many routine dental procedures and it is associated with very high success rates. However, for certain procedures such as endodontic treatment in teeth with irreversible pulpitis success rates can be as low as 23%.

The main aim of this Cochrane review was to compare the success of anaesthesia, the speed of onset and duration of anaesthesia, and systemic and local adverse effects amongst different local anaesthetic formulations for dental anaesthesia.

Methods

Searches were conducted in the Cochrane Central Register of Controlled Trials (CENTRAL) Medline, Embase, CINAHL Plus, Web of Science, IndMED , KoreaMED, Panteleimon,, Australian New Zealand Clinical Trials Registry (ANZCTR), Ingenta Connect , OpenSIGLE , National Research Register ,UK Clinical Research Network (UKCRN) Study Portfolio,and  metaRegister of Controlled Trials databases. This was supplemented by hand searches of the journals, Anaesthesia Progress ,Journal of Endodontics,  International Endodontic Journal, International Journal of Oral /International Journal of Oral and Maxillofacial Surgery ,Oral Surgery, Oral Medicine, Oral Pathology/Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontics /Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, Journal of the American Dental Association ,Pediatric Dentistry, British Dental Journal, Journal of Dental Research, General Dentistry, Journal of the Canadian Dental Association

Randomized controlled trials (RCTs) using a parallel or cross-over design and testing different formulations of local anaesthetic used for clinical procedures or simulated scenarios were considered.  Study selection, data abstraction, assessment of risk of bias and data analysis followed standard Cochrane procedures.

Results

• 123 studies involving a total of 19,223 patients were included.
• Data from 68 studies (6615 patients) contributed to the meta-analysis providing 23 comparisons of local anaesthetic and 57 outcomes with 14 different formulations. Only 10 outcomes from eight comparisons involved clinical testing.
• 15 studies had high risk of bias and 73 had a least one domain with unclear risk of bias.
• Success of anaesthesia
  • When the success of anaesthesia in posterior teeth with irreversible pulpitis requiring root canal treatment is tested, 4% articaine, 1: 100,000 epinephrine, may be superior to 2% lidocaine, 1:100,000 epinephrine (31% with 2% lidocaine vs 49% with 4% articaine; risk ratio (RR) 1.60, 95% confidence interval (CI) 1.10 to 2.32; 4 parallel studies; 203 participants; low-quality evidence).
  • When the success of anaesthesia for teeth/dental tissues requiring surgical procedures and surgical procedures/periodontal treatment, respectively, was tested, 3% prilocaine, 0.03 IU felypressin (66% with 3% prilocaine vs 76% with 2% lidocaine; RR 0.86, 95% CI 0.79 to 0.95; 2 parallel studies; 907 participants; moderate-quality evidence), and 4% prilocaine plain (71% with 4% prilocaine vs 83% with 2% lidocaine; RR 0.86, 95% CI 0.75 to 0.99; 2 parallel studies; 228 participants; low-quality evidence) were inferior to 2% lidocaine, 1:100,000 epinephrine.
  • Comparative effects of 4% articaine, 1:100,000 epinephrine and 4% articaine, 1:200,000 epinephrine on success of anaesthesia for teeth/dental tissues requiring surgical procedures are uncertain (RR 0.85, 95% CI 0.71 to 1.02; 3 parallel studies; 930 participants; very low-quality evidence).
  • Comparative effects of 0.5% bupivacaine, 1:200,000 epinephrine and both 4% articaine, 1:200,000 epinephrine (odds ratio (OR) 0.87, 95% CI 0.27 to 2.83; 2 cross-over studies; 37 participants; low-quality evidence) and 2% lidocaine, 1:100,000 epinephrine (OR 0.58, 95% CI 0.07 to 5.12; 2 cross-over studies; 31 participants; low-quality evidence) on success of anaesthesia for teeth requiring extraction are uncertain.
  • Comparative effects of 2% mepivacaine, 1:100,000 epinephrine and both 4% articaine, 1:100,000 epinephrine (OR 3.82, 95% CI 0.61 to 23.82; 1 parallel and 1 cross-over study; 110 participants; low-quality evidence) and 2% lidocaine, 1:100,000 epinephrine (RR 1.16, 95% CI 0.25 to 5.45; 2 parallel studies; 68 participants; low-quality evidence) on success of anaesthesia for teeth requiring extraction and teeth with irreversible pulpitis requiring endodontic access and instrumentation, respectively, are uncertain.
  • meta-analyses was not possible for other outcomes assessing anaesthesia success
• No clinical studies met the outcome definitions for onset and duration of anaesthesia
• Adverse effects (continuous pain measured on 170-mm Heft-Parker visual analogue scale (VAS))
  • Differences in post-injection pain between 4% articaine, 1:100,000 epinephrine and 2% lidocaine, 1:100,000 epinephrine are small, as measured on a VAS (mean difference (MD) 4.74 mm, 95% CI -1.98 to 11.46 mm; 3 cross-over studies; 314 interventions; moderate- quality evidence). Lidocaine probably resulted in slightly less post-injection pain than articaine (MD 6.41 mm, 95% CI 1.01 to 11.80 mm; 3 cross-over studies; 309 interventions; moderate-quality evidence) on the same VAS.
  • For remaining comparisons assessing local and systemic adverse effects, meta-analyses were not possible. Other adverse effects were rare and minor.
• Patients’ experience of procedures was not assessed owing to lack of data.

Conclusions

The authors concluded: –

For success (absence of pain), low-quality evidence suggests that 4% articaine, 1:100,000 epinephrine was superior to 2% lidocaine, 1:100,000 epinephrine for root treating of posterior teeth with irreversible pulpitis, and 2% lidocaine, 1:100,000 epinephrine was superior to 4% prilocaine plain when surgical procedures/periodontal treatment was provided. Moderate-quality evidence shows that 2% lidocaine, 1:100,000 epinephrine was superior to 3% prilocaine, 0.03 IU felypressin when surgical procedures were performed.

Adverse events were rare. Moderate-quality evidence shows no difference in pain on injection when 4%articaine, 1:100,000 epinephrine and 2% lidocaine, 1:100,000 epinephrine were compared, although lidocaine resulted in slightly less pain following injection.

Many outcomes tested our primary objectives in simulated scenarios, although clinical alternatives may not be possible. Further studies are needed to increase the strength of the evidence. These studies should be clearly reported, have low risk of bias with adequate sample size, and provide data in a format that will allow meta-analysis. Once assessed, results of the 34 ‘Studies awaiting classification (full text unavailable)’ may alter the conclusions of the review.

Comments

This systematic review undertook an extensive search to identify RCTs of all commercially available preparation of local anaesthetics. 14 types of local anaesthetic were tested and from the comparisons that could be made in the review all appeared to be safe and effective.  The findings did show some potential superiority for some types of anaesthetics in some situations. However, the numbers of studies available were small and of moderate quality at best. The discussion section of the review provides a good discussion of the potential biases in the review. The reviewers also highlight issues with the quality of reporting of the original studies and the reviewers point to the need for core outcomes sets which would aid future study comparisons and reviews.  Overall while the review suggests some agents may be more effective there is not sufficient high-quality evidence to determine which is more effective.

Links

Primary study

St George G, Morgan A, Meechan J, Moles DR, Needleman I, Ng YL, Petrie A. Injectable local anaesthetic agents for dental anaesthesia. Cochrane Database of Systematic Reviews 2018, Issue 7. Art. No.: CD006487. DOI: 10.1002/14651858.CD006487.pub2.

Other references

Dental Elf – Local anaesthetic blogs