Plasma levels of lidocaine, o-toluidine, and prilocaine after application of 8.5 g Oraqix in patients with generalized periodontitis: effect on blood methemoglobin and tolerability

Chiral Aspects of Local Anesthetics

Thanks to the progress made in chemical technology (particularly in the methodologies of stereoselective syntheses and analyses) along with regulatory measures, the number of new chiral drugs registered in the form of pure enantiomers has increased over the past decade. In addition, the pharmacological and pharmacokinetic properties of the individual enantiomers of already-introduced racemic drugs are being re-examined. The use of the pure enantiomer of a drug that has been used to date in the form of a racemate is called a "chiral switch". A re-examination of the properties of the pure enantiomers of racemates has taken place for local anesthetics, which represent a group of drugs which have long been used. Differences in (R) and (S)-enantiomers were found in terms of pharmacodynamic and pharmacokinetic activity as well as in toxicity. Levobupivacaine and robivacaine were introduced into practice as pure (S)-(-)-enantiomers, exhibiting more favorable properties than their (R)-(+)-stereoisomers or racemates. This overview focuses on the influence of chirality on the pharmacological and toxicological activity of local anesthetics as well as on individual HPLC and capillary electrophoresis (CE) methods used for enantioseparation and the pharmacokinetic study of individual local anesthetics with a chiral center.

Liposomal anesthetic gel for pain control during periodontal therapy in adults: a placebo-controlled RCT

INTRODUCTION

Periodontal therapy usually requires local anesthesia. If effective, a non-invasive, liposomal anesthetic gel could increase the levels of acceptance of patients in relation to periodontal therapy.

OBJECTIVE

This study investigated the efficacy of liposomal anesthetic gel for pain control during periodontal therapy.

METHODOLOGY

Forty volunteers with moderate to severe chronic periodontitis were recruited, of which at least three sextants required periodontal therapy. At least one of the selected teeth had one site with a probing depth of ≥4 mm. The volunteers received the following three gels: a placebo, lidocaine/prilocaine (Oraqix®), or a liposomal lidocaine/prilocaine, which were applied to different sextants. Pain frequency was registered during treatment and the volunteers received a digital counter to register any painful or uncomfortable experiences. At the end of each session, the volunteers indicated their pain intensity using rating scales (NRS-101 and VRS-4). The volunteers had their hemodynamic parameters measured by a non-invasive digital monitor.

RESULTS

Pain frequency/intensity did not show statistical difference between intervention groups. The tested gels did not interfere with the hemodynamic indices. Dental anxiety, suppuration and probing depth could influence pain during periodontal therapy.

CONCLUSION

Our results suggest limited indications for the use of non-invasive anesthesia when used for scaling and root planing. Intra-pocket anesthetic gel could be a good option for anxious patients, or those who have a fear of needles.

Efficacy of a Light-cured Tetracaine-based Anesthetic Gel for Rubber Dam Clamp Placement: A Triple-blind Randomized Clinical Trial

OBJECTIVES

To evaluate the efficacy of a new light-cured anesthetic gel for pain control in adults undergoing rubber dam isolation for the restorative treatment of noncarious cervical lesions (NCCLs).

METHODS AND MATERIALS

This study was a randomized, split-mouth, triple-blind, controlled trial. The sample comprised 50 adults with at least one pair of NCCLs located in the same arch but on opposite sides. Simple randomization defined the tooth to receive the light-cured tetracaine-based anesthetic gel or the placebo gel. After cotton roll isolation, the gels were applied in the gingival tissue around the tooth with the aid of the applicator tip of a syringe, left in place for 15 seconds, and light-cured for 15 seconds. Then, a #212 clamp was positioned on the tooth. If the patient reported pain, the clamp was removed, the patient filled out a pain intensity form (a 0-10 visual analog scale [VAS] and a 0-4 verbal rating scale [VRS]) and an injectable anesthetic was applied before rubber dam isolation for the restorative procedure. The absolute risk, intensity of pain, and need for rescue anesthesia were analyzed by the McNemar test and the Wilcoxon signed rank test (α=5%).

RESULTS

The odds ratio [OR] for pain (OR=3.5; 95% confidence interval [CI]=1.1 to 14.6; p=0.03) showed lower reports of pain for the light-cured anesthetic gel. One in five patients will benefit from placement of the light-cured anesthetic gel. On average, pain intensity was one VAS unit lower in those using the light-cured anesthetic gel than in those using the placebo gel. For the VRS, the pain intensity for the light-cured anesthetic gel was 0.4 units lower than the pain intensity for the placebo gel (95% CI=-0.9 to 0.07). The OR for rescue anesthesia was 2.5 (95% CI=0.7 to 10.9; p=0.18).

CONCLUSIONS

The light-cured, tetracaine-based anesthetic gel reduced the absolute risk of pain by 20% in NCCLs.

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.

Topical intrapocket anesthesia during scaling and root planing: a randomized clinical trial

Although the use of injectable anesthesia prior to subgingival scaling and root planing (SRP) reduces pain, many patients report fear and prolonged numbness of adjacent tissues. The aim of the present study was to compare the effects of a eutectic mixture containing 25 mg/g of lidocaine and 25 mg/g of prilocaine, injectable 2% lidocaine, topical 2% benzocaine and a placebo substance on reducing pain during SRP. In this randomized, split-mouth, masked clinical trial, thirty-two patients presenting more than two teeth with probing depth and clinical attachment level ≥ 5 mm in at least 4 sextants were randomly allocated to four groups: EMLA(r); injectable 2% lidocaine; topical 2% benzocaine and placebo. Pain and discomfort were measured using a visual analogue scale (VAS) and verbal scale (VS). Repeated-measures analysis of variance and Poisson regression were used for analysis. Patient satisfaction with the anesthesia was determined at the end of each treatment session. VAS and VS scores did not differ between injectable 2% lidocaine and EMLA (p > 0.05) and both substances showed significantly better pain control compared to 2% benzocaine and placebo (p < 0.05). 93.7% and 81.2% of the individuals were satisfied with the injectable anesthetic and EMLA, respectively (p = 0.158). Dissatisfaction with benzocaine and placebo was approximately 10 times greater than injectable anesthesia (p = 0.001). In conclusion, EMLA showed an equivalent effect on pain control when compared to the injectable anesthesia and performed better than 2% benzocaine in SRP. Thus, EMLA is a viable anesthetic option during scaling and root planning, despite the frequent need for second application.

Anesthetic efficacy of Oraqix® versus Hurricaine® and placebo for pain control during non-surgical periodontal treatment

Objectives: To evaluate the efficacy of Oraqix® during scaling and root planing (SRP) in comparison with 20% benzocaine and placebo. Study Design: 15 patients requiring 4 sessions of SRP were enrolled. For each patient, Oraqix®, Hurricaine®, vaseline or no anesthetic product were randomly assigned each to a quadrant. Treatment pain was evaluated on a 100 mm Visual Analog Scale (VAS) and on a Verbal Rating Scale (VRS). The amount of product administered, the need to re-anesthetise, patient and operator satisfaction and the onset of side-effects were also recorded. Results: Oraqix® was significantly better than nothing, with a reduction of VAS score to 13.3 units, but without significant differences with Vaseline or Hurricaine®. Oraqix® was better in VRS reduction than not using any anesthetic (p=0.001) or using vaseline (p=0.024), but similar to Hurricaine® (p=0.232). Conclusions: Oraqix® effectively controls pain in SRP procedures, with few side-effects and a good acceptance on the part of patients and clinicians.

Key words:Controlled clinical trial, topical anesthetic, scaling and root planing.

Pocket-depths-related effectiveness of an intrapocket anaesthesia gel in periodontal maintenance patients

AIM

The aim of this study was to determine the impact of the pocket depth on the effectiveness of an intrapocket anaesthesia gel during SRP in periodontal maintenance patients. Effectiveness was measured by pain levels during SRP via visual analogue scale (VAS) and verbal rating scale (VRS). Secondary endpoint was the evaluation of patients' preferred choice of anaesthesia for SRP.

METHODS

A total of 638 patients undergoing the periodontal maintenance programme and with the need for SRP participated in this observational study. After SRP, patients filled in questionnaires to record pain levels experienced and anaesthesia preference for future use. Mann-Whitney U-test was used to analyse intergroup difference in pain perception and anaesthesia choice.

RESULTS

Overall, increasing pocket depths were accompanied by higher pain levels, irrespective of maximum or commonest pocket depths (P < 0.05). For SRP procedures, patients definitely prefer the anaesthesia gel (72.4%).

CONCLUSIONS

In this study, an effectiveness of local anaesthesia gel (lidocaine/prilocaine) related to pocket depths was found in periodontal maintenance patients during SRP. Increasing pocket depths were accompanied by increasing procedural pain levels. Nevertheless, the anaesthesia gel is well accepted and in the majority of cases was found to be the preferred option for future SRP treatments.

Healing pattern of experimental soft tissue lacerations after application of novel topical anesthetic agents - an experimental study in rabbits

Topical anesthetics based on a combination of 2.5% lidocaine and 2.5% prilocaine are efficient in eliminating pain from needle stick when placed on skin and oral mucosa. This suggests their application in soft tissue lacerations before suturing to enable pain-free exploration and suturing of traumatic lacerations without prior injection needle stick. The aim of the present study was to study the healing of experimental oral lacerations after topical anesthetic substances were placed in the lacerations. Thirty-six standardized incisions were made bilaterally in the lower and the upper labial mucosa of nine white New Zealand rabbits. All wounds were intentionally contaminated with saliva to simulate laceration wounds in trauma situation. EMLA cream and Oraqix thermosetting gel were applied into 30 lacerations and six lacerations were left untreated as control. In some lacerations the topical anesthetic agent was left in the wound, while in others they were rinsed off by saline before suturing the laceration wound. The rabbits were then killed after 3 days, 2 weeks and 4 weeks of healing and the lips were processed for histological evaluation. Similar normal histological healing patterns were seen in wounds in which EMLA and Oraqix were applied compared with control lacerations at all stages of healing. No adverse tissue or foreign body reactions were seen in any of the lacerations. We conclude that EMLA and Oraqix can be used in oral mucosal lacerations prior to suturing without the risk of adverse tissue reaction.

Comparison of topical anesthetics (EMLA/Oraqix vs. benzocaine) on pain experienced during palatal needle injection

OBJECTIVE

The aim of this study was to compare the topical anesthetic effect of 20% benzocaine gel with 2.5% lidocaine/2.5% prilocaine (L/P) cream and gel on the pain experienced during palatal anesthetic infiltration.

STUDY DESIGN

Two groups were studied, each containing 20 subjects. Two types of L/P mixtures were tested, an anesthetic cream (EMLA) and a thermosetting gel (Oraqix), and benzocaine was used as control. The topical agents were applied on the palatal mucosa at the canine region. A needle prick was given on each side every 2 minutes during a period of 10 minutes. The subjects recorded their findings using verbal and VAS scales.

RESULTS

Pain scores were significantly less (P < .05) with EMLA and Oraqix than with benzocaine.

CONCLUSION

Topical application of EMLA and Oraqix before palatal anesthetic infiltration is associated with less pain than with benzocaine gel.

Hemoglobin adducts of the human bladder carcinogen o-toluidine after treatment with the local anesthetic prilocaine

Prilocaine, a widely used local anesthetic, is metabolized to o-toluidine which is classified as human carcinogen. We aimed to assess the impact of prilocaine-treatment on hemoglobin adducts from o-toluidine. Blood samples were obtained before and 24h after receiving prilocaine local anesthesia (Xylonest, 100mg) from 20 head and neck surgery patients and 6 healthy volunteers. Hemoglobin adducts of o-toluidine and 4-aminobiphenyl were determined by gas chromatography/mass spectrometry. Hemoglobin adducts of o-toluidine were significantly increased 24h after 100mg prilocaine-treatment by 21.6+/-12.8ng/g hemoglobin (mean+/-S.D., N=26; P<0.0001). This corresponds to a 6-360-fold increase of o-toluidine adduct levels in 25 patients from 0.54+/-0.95ng/g before treatment to 22.0+/-13.2ng/g 24h after surgery (mean+/-S.D.). Because of an extremely high background level the increase was only 1.6-fold in one patient (40.9ng/g before and 64.4ng/g 24h after prilocaine injection). Current smoking had no influence on background values and on the increase of o-toluidine adducts. No treatment-related differences were seen in mean hemoglobin adduct levels of 4-aminobiphenyl which were significantly higher in smokers, 0.149+/-0.096ng/g (mean+/-S.D., N=8) as compared to nonsmokers 0.036+/-0.035ng/g (mean+/-S.D., N=16; P<0.01). In conclusion, prilocaine anesthesia leads to a massive increase of hemoglobin adducts of the carcinogenic arylamine o-toluidine. This implies a carcinogenic risk which should be taken into account in preventive hazard minimization.