Recent advances in local anaesthesia

Ice versus lidocaine 5% gel for topical anaesthesia of oral mucosa - a randomized cross-over study

BACKGROUND

Topical anaesthesia is important to optimize pain control during dental injection. Our aim was to describe a new simple method for topical anaesthesia of oral mucosa and to compare the effectiveness of ice and lidocaine 5% gel for topical anaesthesia of oral mucosa.

METHODS

A total of 40 patients aged 10.7-19.5 years were included. The side and method of application were both randomized. Heart rate was recorded, and discomfort and pain were evaluated with a visual analogue scale (VAS). A paired t-test was used to compare mean values, a chi² test was used to compare proportions, and a Pearson correlation test was used to examine correlations between variables.

RESULTS

When ice was used, buccal injection VAS pain was rated lower (p = 0.044), and VAS discomfort was rated higher (p = 0.001), in comparison to when lidocaine 5% gel was used. There was no significant difference in relative heart rate change between ice and lidocaine 5% gel at either needle stick or injection. Lidocaine 5% gel produced a relative heart rate reduction after palatal injection (0.99 ± 0.06) while buccal injection produced an increased relative heart rate (1.02 ± 0.08) (p = 0.010). Unpleasant taste was more frequently reported when lidocaine 5% gel was used (p = 0.025). An application time of 1 min was sufficient for both ice and lidocaine 5% gel to achieve pain reduction from needle stick in buccal mucosa.

CONCLUSION

The cheap and readily available described method using ice for topical anaesthesia of oral mucosa before dental injection is an effective alternative to lidocaine 5% gel.

TRIAL REGISTRATION

The European Union Drug Regulating Authorities Clinical Trials Database EudraCT201300530531. Date of registration: February 10th, 2014.

Are Local Anesthesia Vials Similar to Champagne: Do they Lose their Potency Once Opened?: An In vitro study

BACKGROUND AND OBJECTIVES

Epinephrine is volatile and unstable on exposure to air. Addition of sodium metabisulfite as an antioxidant has been effective, but there are no clear-cut consensus on its efficiency in retarding the oxidation that sets in once the anesthetic vials are kept open with a needle in situ. There is a paucity of scientific data regarding the risks of reuse of anesthetic vials following the use of cartridges, a common practice in western countries. It is our endeavor to shed light on the constant change in pH, drug deterioration, and instability that sets in an anesthetic vial with a needle in situ.

METHODS

Twenty sets of identical local anesthetic vials (lidocaine 2% with 1:80,000 adrenaline) were collected. The samples were divided into four individual groups followed by a segregation of 5 subsamples at varying time intervals from each individual group. pH was measured using pH meter.

RESULTS

Change in the pH of the solution was noted as days progressed in open local anesthetic vials when compared to closed vials. However, the decreased pH remained constant following a brief time interval after complete conversion of sulfite to sulfate.

CONCLUSIONS

Local anesthetic vials with needle pricked in for a longer duration can alter the pH, concentration of the vasoconstrictor and deteriorate the properties of local anesthetic solution. This can manifest clinically as delayed onset of action, increased burning sensation, and pain on administration.

Recent advances in topical anesthesia

Topical anesthetics act on the peripheral nerves and reduce the sensation of pain at the site of application. In dentistry, they are used to control local pain caused by needling, placement of orthodontic bands, the vomiting reflex, oral mucositis, and rubber-dam clamp placement. Traditional topical anesthetics contain lidocaine or benzocaine as active ingredients and are used in the form of solutions, creams, gels, and sprays. Eutectic mixtures of local anesthesia cream, a mixture of various topical anesthetics, has been reported to be more potent than other anesthetics. Recently, new products with modified ingredients and application methods have been introduced into the market. These products may be used for mild pain during periodontal treatment, such as scaling. Dentists should be aware that topical anesthetics, although rare, might induce allergic reactions or side effects as a result of an overdose. Topical anesthetics are useful aids during dental treatment, as they reduce dental phobia, especially in children, by mitigating discomfort and pain.

Methylparaben concentration in commercial Brazilian local anesthetics solutions

Objective

To detect the presence and concentration of methylparaben in cartridges of commercial Brazilian local anesthetics.

Material and methods

Twelve commercial brands (4 in glass and 8 in plastic cartridges) of local anesthetic solutions for use in dentistry were purchased from the Brazilian market and analyzed. Different lots of the commercial brands were obtained in different Brazilian cities (Piracicaba, Campinas and São Paulo). Separation was performed using high performance liquid chromatography (HPLC) with UV-Vis detector. The mobile phase used was acetonitrile:water (75:25 - v/v), pH 4.5, adjusted with acetic acid at a flow rate of 1.0 ml.min^-1.

Results

When detected in the solutions, the methylparaben concentration ranged from 0.01% (m/v) to 0.16% (m/v). One glass and all plastic cartridges presented methylparaben.

Conclusion

1. Methylparaben concentration varied among solutions from different manufacturers, and it was not indicated in the drug package inserts; 2. Since the presence of methylparaben in dental anesthetics is not regulated by the Brazilian National Health Surveillance Agency (ANVISA) and this substance could cause allergic reactions, it is important to alert dentists about its possible presence.

Lidocaine 20% patch vs lidocaine 5% gel for topical anaesthesia of oral mucosa

BACKGROUND

Topical anaesthetics are important to provide pain control at dental injection.

AIM

The aim was to evaluate the effectiveness of the intraoral topical anaesthetics lidocaine 20% patch (DentiPatch) and lidocaine 5% gel.

DESIGN

The randomized unblinded cross-over study included 31 patients (ten boys, 21 girls) aged 13.5 +/- 2.5 years. Application of lidocaine patch or gel was randomly used at first and second visit in the upper premolar region. Heart rate was measured before and at each needle insertion after 2.5, 5, and 15 min and at injection after 15 min. Discomfort and pain were expressed in visual analogue scales (VAS). Paired t-test and Mann-Whitney U-test were used for statistic analyses.

RESULTS

Heart rate at buccal injection decreased more when the patch was used (P = 0.0149). Heart rate was lower at the second visit (P = 0.0287). Patients expressed less discomfort when the patch was used on both buccal (P = 0.0150) and palatal (P = 0.0391) site. Boys had lower heart rate and VAS pain scale ratings than girls.

CONCLUSIONS

Good pain control can reduce the patients' anxiety level--expressed in heart rate--at the second appointment. The patch and gel seem to provide similar pain reduction at needle stick and injection of local anaesthetics.

A concise review of the basic biology and pharmacology of local analgesia

Local analgesics are the most commonly used group drugs in dental practice. However, due to their frequent use and high margin of safety, often dental practitioners neglect to properly understand the biology and pharmacology of these drugs. This article reviews the basic concepts of pain, pain pathways, the mode of action of local analgesics and factors which affect their usage. Specific details and properties of some currently available solutions are also outlined. A greater understanding of the biology and pharmacology of local anaesthetics will ultimately lead to safer and more effective use in everyday clinical practice.