Severe adverse reactions to dental local anaesthetics: systemic reactions

[Principles of the pharmacology of local anesthetics]

The development of local anesthetics revolutionized the performance of painful interventions. Local anesthetics have an effect on voltage-gated sodium channels in nerve fibers and modulate the conduction of impulses. With respect to the chemical structure, local anesthetics can be divided into amide and ester types. The structural differences of local anesthetics have an influence on the duration of action, the degradation pathways and specific side effects. Severe adverse events include cardiotoxicity and neurotoxicity. In addition to basic measures, such as the monitoring and securing of vital parameters, lipid infusion represents a treatment option in cases of intoxication. The recent developments of local anesthetics are particularly concerned with the reduction of toxicity and prolonging the duration of action.

Functional neurologic disorder as a rare complication of dental local anaesthetics: two contrasting cases

Adverse reactions to dental local anaesthetics are fortunately rare. However, when they occur, they can be severe and debilitating to the patient. Adverse reactions may be either prolonged anaesthesia, with or without dysaesthesia, or systemic reactions. Although these systemic reactions are commonly thought to be allergies, this is rarely the case. Much more commonly, these adverse systemic reactions are either cardiovascular or from the central nervous system. This paper describes two contrasting cases of functional neurologic disorder which illustrates the consequences and appropriate management. The responsibilities of the dentist who injected the local anaesthetic are outlined.

[Principles of the pharmacology of local anesthetics]

The development of local anesthetics revolutionized the performance of painful interventions. Local anesthetics have an effect on voltage-gated sodium channels in nerve fibers and modulate the conduction of impulses. With respect to the chemical structure, local anesthetics can be divided into amide and ester types. The structural differences of local anesthetics have an influence on the duration of action, the degradation pathways and specific side effects. Severe adverse events include cardiotoxicity and neurotoxicity. In addition to basic measures, such as the monitoring and securing of vital parameters, lipid infusion represents a treatment option in cases of intoxication. The recent developments of local anesthetics are particularly concerned with the reduction of toxicity and prolonging the duration of action.

Knowledge, Practice and Self-Reported Confidence Level of Croatian Dentists in the Use of Local Anesthesia: A Cross-Sectional Study

Objectives: To provide safe and effective local anesthesia, dentists must have knowledge of neuroanatomy, anesthesia agents, techniques, equipment, and proper use of local anesthetics. This study aims to explore the knowledge, practices, and confidence regarding local anesthetics and anesthetic techniques in dentistry. Material and Methods: The online cross-sectional questionnaire was conducted via social media, and yielded 441 responses from across the country (69.8% women and 30.2% men; 70.7% general dentists; and 29.3 specialists). The data collected included sociodemographic characteristics, knowledge, and practices pertaining to the usage of local anesthesia. The questionnaire also documents their self-assessed confidence level in applying different local anesthetic techniques and experiences with adverse reactions. The obtained data were processed by description and using a generalized linear model for regression. Results: The respondents had a median knowledge score of 6 out of a possible 14 points regarding local anesthetics in dental medicine, and their median self-confidence level in the successful application of various techniques of local anesthesia was 54 out of a maximum of 85 points. The results showed that a higher knowledge level was associated with the female gender (OR 1.83, CI 1.13-2.98, p = 0.014) and specialization in oral surgery (OR 7.04, CI 1.71-29.07, p = 0.007). In contrast, a lack of confidence in using various local anesthetic techniques was also associated with the female gender (OR 0.63, CI 0.41-0.99, p = 0.047) and specialization in orthodontics (OR 0.16, CI 0.03-0.88, p = 0.035). Of the respondents, 81.4% (n = 371) experienced a local complication, and 42.2% (n = 186) experienced a systemic complication during local anesthesia. The complications experienced cannot be associated with a lack of knowledge or self-confidence (p > 0.05). The majority of respondents (364 of the 441 total-82.5%) expressed interest in receiving further education on the topic of local anesthesia. Conclusions: The research results show that the dentists involved in the study have poor knowledge of local anesthetics and moderate self-reported confidence levels in using various local anesthetic techniques. Moreover, dentists' self-confidence in applying different techniques of local anesthesia is not related to their knowledge. Therefore, it would be necessary for dentists to undergo a continuing dental education program that enables them to enhance their skills and knowledge in local anesthesia.

Local anesthetics systemic toxicity in children: analysis of the French pharmacovigilance database

PURPOSE

To characterize clinical profile of pediatric local anesthetic (LA) systemic toxicity (LAST) and to identify determinants of life-threatening outcomes.

METHODS

Spontaneous reports notified to the French Pharmacovigilance Network were retrieved and followed by a case-by-case review, according to the following criteria: LA as suspected drug, age < 18 years, adverse drug reactions related to nervous system, cardiac, respiratory, psychiatric or general disorders. Multivariate logistic regression analysis was performed to identify factors leading to life-threatening reaction (i.e. continuous seizures or cardiorespiratory arrest).

RESULTS

Among 512 cases retrieved, 64 LAST cases were included (neonates 11%, infants 30%, children 36%, adolescents 23%) mainly involving lidocaine (47%), lidocaine + prilocaine (22%) and ropivacaine (14%). Toxicity profiles were neurological (58%), cardiac (11%) or mixed (20%) and 7 patients (11%) developed methemoglobinemia. LAST was life-threatening for 23 patients (36%) and 2 patients died. Doses were above recommendations in 26 patients (41%) and were not different between life-threatening and non-life-threatening cases. The context of use (general and orthopedic surgery, p = 0.006) and the type of LA agent (lidocaine, p = 0.016) were independently associated with a life-threatening outcome.

CONCLUSION

In this national retrospective analysis, LAST in children appear to be a rare event. Neurological and cardiac signs were the most frequently reported reactions. LAST in children can be life-threatening, even at therapeutic doses. Although a fatal outcome may anecdotally occur, the vast majority of patients recovered after appropriate medical care.

Present status and future directions - Mechanisms and management of local anaesthetic failures

Pain control during root canal treatment is of utmost importance for both the patient and the dental practitioner and many studies have investigated ways of overcoming problems with gaining adequate anaesthesia during treatment. The PubMed and Cochrane databases were searched for evidence-based studies regarding local anaesthesia for root canal treatment. Many variables, including premedication, pain during needle insertion, pain on injection, premedication with various types of drugs, volume of anaesthetic solutions, supplemental anaesthetic techniques, and additives to the anaesthetic solutions, may influence pain perception during root canal treatment. Differences between teeth with healthy pulps versus those with irreversible pulpitis should be considered when the effects of variables are interpreted. There are several concerns regarding the methodologies used in studies that have evaluated anaesthesia success rates. There are some conditions that may help to predict a patient's pain during root canal treatment and these conditions could be overcome either by employing methods such as premedication with a non-steroidal anti-inflammatory drug prior to the treatment visit or by using supplementary anaesthetic techniques before or during the treatment. However, authors need to be more careful when reporting details of their studies to reduce concerns regarding their study bias.

Anaphylactic reactions to local anesthetics in dental practice: a nationwide French retrospective study

OBJECTIVES

The primary aims of the present study were (1) to quantify and characterize anaphylactic type I reactions related to local anesthetics (LAs) drawing on the French Pharmacovigilance Database System over a 35-year period and (2) to focuse on reactions associated with dental procedures. The secondary aim was to infer an incidence rate in dental practice.

MATERIALS AND METHODS

All cases of anaphylactic reactions were selected using the algorithmic Standardized MeDRA Query "anaphylactic reaction." For each reaction, comprehensive data were collected, in particular the severity of symptoms, risk factors for anaphylaxis, and allergy testing. Imputability was assessed and a crude incidence rate in dental practice was estimated.

RESULTS

The first-line search identified 416 anaphylactic reactions, mostly of grade II (138) or III (240) severity. When restricted to dental practice, this number fell to 26 (grade I: 4; grade II: 10; grade III: 11; and grade IV: 1). Lidocaine was most often involved (81.49%) and mostly associated with anaphylactic reactions of grade II and III. Overall, 11 cases of fatal anaphylaxis were recorded, but no in dental practice. In dental practice, lidocaine was also the most frequently involved LA (57.69%).

CONCLUSIONS

All these findings highlight the very low incidence of type I-IgE-mediated reactions to LA, particularly in dental practice. The incidence rate of LA anaphylctic episodes in dental practice was estimated as 0.0261 anaphylactic episodes per million LA cartridges.

CLINICAL RELEVANCE

True anaphylactic reactions to LAs do occur and may justify a thorough investigation in dental practice.

Does the use of topical anesthetics reduce the perception of pain during needle puncture and anesthetic infiltration? Systematic review and meta-analysis of randomized controlled trials

The objective of this systematic review was to assess whether the use of topical anesthetics reduces the perception of pain during puncture and anesthetic infiltration. Twenty-two randomized controlled clinical trials, published in English on or before August 6, 2020, were found in the PubMed/MEDLINE, Scopus, and Cochrane Library databases. Risk of bias was determined for randomization and other issues. A total of 1029 patients were evaluated using parameters such as type of topical anesthetic, application site, and pain (measured on a scale). Some studies assessed more than one topical anesthetic. Seventeen of them showed a reduction in pain from needle puncture and four from infiltration. Meta-analyses for some results showed considerable statistical heterogeneity. Regarding pain during needle puncture of the maxilla, statistically significant differences were observed in the topical anesthetics group, in both the vestibular (P = 0.0002) and palatal (P = 0.005) region. This was different from the mandible, for which there was no statistically significant difference (P = 0.07). With regard to pain caused by anesthetic infiltration in the maxilla, there was no difference in the use of anesthetic in relation to the control group (P = 0.11). Given these findings, using topical anesthetics only relieves pain during needle puncture and in the maxilla. PROSPERO 2020: CRD42020206362.

Successful Dental Treatments Using Procaine Hydrochloride in a Patient Afraid of Local Anesthesia but Consenting for Allergic Testing with Lidocaine: A Case Report

Background

We report a case in which effective dental anesthetic management was achieved using procaine hydrochloride for a patient who had an unknown history of allergic reactions to lidocaine.

Case Presentation

Because the patient refused to undergo screening tests using any of the amide-type local anesthetics because of her extreme fear against local anesthetics that she had been administered previously, procaine hydrochloride, which is an ester-form local anesthetic, was the only agent to be tested on this patient at the department of dermatology. Consequent to a negative allergy test, we performed complete dental treatment using procaine hydrochloride after additional chairside drug challenge tests using minimum test dose under vital sign monitoring.

Conclusion

The success of dental treatment using procaine hydrochloride may have relieved the patient's fear of local anesthesia. We discuss an important aspect of treatment planning for patients with a history of complications during local anesthesia.

Observational study of adverse reactions related to articaine and lidocaine

PURPOSE

This study determined the frequency of adverse reactions related to the administration of local dental anesthesia with 4% articaine compared with 2% lidocaine, both associated with epinephrine 1:100,000. The null hypothesis was that there is no difference between the administrations of both dental local anesthesia.

METHODS

From a total of 727 patients in an emergency service, 338 and 389 patients were subjected to local anesthesia with lidocaine and articaine, respectively. A questionnaire was completed for each patient that contained patient data, the local anesthesia applied, and any reactions.

RESULTS

The overall frequency of adverse reactions was 3.71%, with sweating and pallor being the most frequently observed. There was an association between adverse reactions and the use of daily medication by patients anesthetized with articaine (p = 0.0266). In contrast, in patients anesthetized with lidocaine, there was an association among the duration of the procedure (p = 0.0423), the type of procedure (p = 0.0146), and first anesthesia exposure (p = 0.0448).

CONCLUSIONS

The low frequency of adverse reactions with use of articaine and lidocaine led to the conclusion that both solutions are safe for use in dentistry.

French clinical guidelines for peripheral motor nerve blocks in a PRM setting

INTRODUCTION

Motor nerve blocks with anesthetic drug for local anesthesia are commonly used in physical and rehabilitation medicine (PRM), especially in the field of spasticity. Guidelines in this context are currently lacking.

METHOD

Eighteen experts selected on the basis of their recognized experience by the scientific committees of the French PRM (SOFMER) and Anesthesia and Intensive care (SFAR) societies were invited to work and propose guidelines for the use of loco-regional anesthetic drug for motor nerve blocks in PRM setting. Eight issues were addressed: which neural blocks for which indications; drugs and contraindications; medical survey and attitude in case of adverse event; injection and guidance material; patient preparation and pain relief; efficacy assessment; patient information; education of PRM physiatrists. The Medline, Cochrane and Embase databases for the period 1999 to 2018 were consulted and 355 papers analyzed. The drafts were commented then approved by the whole group using electronic vote, before final approval by scientific committee of each society.

RESULTS

No scientific evidence emerged from the literature. Thus, these guidelines are mainly based on the opinion of the expert panel. Guidelines for each issue are reported with the main points of arguments. The main question deals with the recommendation about doses for each drug: for lidocaine - up to 2mg/kg - "check contraindications, emergency truck available, no need of previous anesthetic consultation nor presence of anesthetic physician"; for ropivacaine - up to 1.5mg/kg, with a maximum of 100mg - the same but after intravenous line. Beyond these doses, SFAR guidelines have to be applied with the need of anesthetic physician.

CONCLUSION

These are the first organizational guidelines devoted to increase the security of motor nerve block use in PRM settings.

Immunotherapy of lidocaine allergy by intravenous desensitization using IFN-gamma from a case: Overcoming impediments using IFN-gamma during desensitization

Anaphylactic reaction to lidocaine has been reported during a dental procedure. In this trial, a patient who required local anesthesia for dental treatment was desensitized successfully to intravenous lidocaine using IFN-gamma. Practical general protocols and principles are suggested for the general application of this method for other intravenous drugs.

Proposal of a trigger tool to assess adverse events in dental care

The aim of this study was to propose a trigger tool for research of adverse events in outpatient dentistry in Brazil. The tool was elaborated in two stages: (i) to build a preliminary set of triggers, a literature review was conducted to identify the composition of trigger tools used in other areas of health and the principal adverse events found in dentistry; (ii) to validate the preliminarily constructed triggers a panel of experts was organized using the modified Delphi method. Fourteen triggers were elaborated in a tool with explicit criteria to identify potential adverse events in dental care, essential for retrospective patient chart reviews. Studies on patient safety in dental care are still incipient when compared to other areas of health care. This study intended to contribute to the research in this field. The contribution by the literature and guidance from the expert panel allowed elaborating a set of triggers to detect adverse events in dental care, but additional studies are needed to test the instrument's validity.

Investigation and diagnosis of an immediate allergy to amide local anaesthetic in a paediatric dental patient

Local anaesthetics remain the most common prescription medication utilized in dental practise. Adverse reactions following administration of local anaesthetic are somewhat common and are frequently reported as 'allergies'. However, of these events, it is estimated that only 1% are confirmed allergies to the local anaesthetic. This case report presents the process of referral for investigation and testing to confirm an amide local anaesthetic allergy in a paediatric patient. Testing for a safe alternative was also completed to identify local anaesthetic agents also of the amide variety that could be utilized safely on this individual. Following skin testing of alternative agents, intraoral challenges were completed. Finally, restorative dental treatment was provided safely for the patient with the use of an alternative amide local anaesthetic on a number of occasions with no further adverse outcomes.

A case of severe NSAID exacerbated respiratory disease (NERD) following a dental procedure in a child

BACKGROUND

An allergic reaction following a dental procedure is a rare event. A local anaesthetic (LA) may initially be suspected as a causative agent but allergy to dental LA solutions is extremely rare.

CASE REPORT

This report concerns a 13 year old child who underwent dental treatment and was exposed to Lignospan Special(®) LA, mouthwash, latex gloves, ibuprofen medication, and a Magnum(®) (almond) ice cream all within 45 min. He subsequently developed acute symptoms of nasal rhinorrhoea, facial flushing, peri-orbital and lip angioedema, followed by throat tightness and wheeze (respiratory compromise). His acute reaction was treated by his medical practitioner with oral anti-histamines, steroid and nebulised salbutamol. The child was referred to a local allergist. The child underwent detailed allergic investigations including skin prick tests, blood tests, incremental local anaesthetic challenge and ibuprofen challenge. The patient was diagnosed with NSAID exacerbated respiratory disease (NERD), a hypersensitivity reaction to ibuprofen.

FOLLOW-UP

The patient was advised to avoid NSAIDs and to wear a medic-alert (allergy) bracelet. A detailed written report was sent to the patient's dentist and GP.

CONCLUSIONS

In the context of a suspected reaction post dental procedure, local anaesthetic should be considered a possible allergen but other important considerations include analgesics, antibiotics, and latex. All genuine allergic reactions need to be investigated. This report highlights NERD as a possible adverse outcome following dental treatment.

Does root canal treatment in necrotic pulp or retreatment cases with periapical lesions require anaesthesia? An in vivo clinical study

AIM

To examine whether local anaesthesia is required for treating teeth with necrotic pulps (TNP) and retreatment cases (RCs) associated with periapical lesions.

METHODOLOGY

Root canal treatment was performed in TNP and RCs without the administration of local anaesthesia. Patients were assured that if they experienced pain, local anaesthesia would be provided. Eighty canals, 40 TNP and 40 RCs, were included in the study. Two length measurements were performed: one using an electronic apex locator (EAL), which was defined as the electronic length (EL), and the second, the length at which the patient first reported that a size 15 file was touching the periapical tissues, which was defined as the periodontal length (PL). The difference between these two measurements (Δ = PL - EL) was the parameter studied. Statistical analysis was conducted using two-way anova and paired t-tests. Working length (WL) was defined in this study as being 0.5 mm short of the EL.

RESULTS

EL was shorter than PL in 96% of cases. The mean difference between measurements was 0.78 (±0.11) mm in the TNP group and 0.63 (±0.15) mm in the RC group; the difference was not significant. The distances between the WL and PL were thus 1.28 and 1.13 mm, respectively. In none of the 80 canals did the patient experience any pain, either during the measurements or during the instrumentation procedures.

CONCLUSIONS

When EALs are used, local anaesthesia may not be required for root canal treatment in teeth with necrotic pulps and retreatment cases associated with periapical lesions.

Lidocaine-induced methemoglobinemia: a clinical reminder

Methemoglobinemia is a rare condition in which the iron in hemoglobin is stabilized in the ferric (Fe(3+)) form, making it unable to bind oxygen and leading to tissue hypoxia and possibly death. The condition may be hereditary or acquired, the latter resulting from ingestion or application of common oxidizing agents such as lidocaine. As management of methemoglobinemia depends on prompt recognition, clinicians who administer or prescribe oxidizing agents must be aware of the clinical symptoms of methemoglobinemia, including cyanosis, pulse oximetry values that do not respond to increased oxygen delivery, and altered mental status. Currently, methylene blue is the drug of choice for the management of methemoglobinemia.

Plasma mepivacaine concentrations in patients undergoing third molar surgery

BACKGROUND

Local anaesthetic-related systemic toxicity mainly results from elevated plasma concentrations of these drugs. We hypothesized that intraoral injection of submaximal doses of mepivacaine does not lead to toxic levels of this drug in blood. This study evaluated the plasma levels of mepivacaine in third molars surgeries.

METHODS

Twenty-one patients were randomly assigned into two groups: group I (two unilateral third molars; submaximal dose of mepivacaine 108 mg with epinephrine 54 μg) and group II (four third molars; submaximal dose of mepivacaine 216 mg with epinephrine 108 μg). Blood samples were collected before anaesthesia, and 5, 10, 15, 20, 30, 40, 60, 90 and 120 min after anaesthesia.

RESULTS

Individual peak plasma concentrations ranged 0.77-8.31 μg/mL (group I) and from 2.36-7.72 μg/mL (group II). An increase in the average dose of mepivacaine from 1.88 ± 0.12 mg/kg (group I) to 3.35 ± 0.17 mg/kg (group II) increased the mean mepivacaine peak plasma levels from 2.33 ± 0.58 to 4.01 ± 0.69 μg/mL, respectively. Four patients obtained plasma levels of mepivacaine above the threshold for toxicity (5 μg/mL).

CONCLUSIONS

Toxic levels of mepivacaine are possible, even when a submaximal dose is used. A twofold increase in the dose of mepivacaine caused the mean peak plasma concentration to increase proportionally, indicating that they may be predicted based on the relation of dose per bodyweight.

An unusual ocular complication following dental anaesthesia: case report

Used routinely by dental practitioners, local anaesthetics are generally a safe and effective means of achieving pain control during invasive dental procedures. Delivery, however, is technique sensitive and the potential for patient complication exists. Although reasonably rare, ocular complications have occurred, often leaving the patient and the clinician in distress. Such reported events have almost always involved tissue responses ipsilateral to the injection site. The current case report presents an unusual event involving involuntary fasciculation or hemifacial spasm and eventual eyelid closure on the contralateral side following a routine inferior alveolar nerve block. Aspects including the patient's history, the observed response, a pathophysiological hypothesis and patient management are discussed.

Allergic Reactions to Dental Materials-A Systematic Review

INTRODUCTION

Utility of various dental materials ranging from diagnosis to rehabilitation for the management of oral diseases are not devoid of posing a potential risk of inducing allergic reactions to the patient, technician and dentist. This review aims to develop a systematic approach for the selection and monitoring of dental materials available in the market thereby giving an insight to predict their risk of inducing allergic reactions.

MATERIALS AND METHODS

Our data included 71 relevant articles which included 60 case reports, 8 prospective studies and 3 retrospective studies. The source of these articles was Pub Med search done with the following terms: allergies to impression materials, sodium hypochlorite, Ledermix paste, zinc oxide eugenol, formaldehyde, Latex gloves, Methyl methacrylate, fissure sealant, composites, mercury, Nickel-chromium, Titanium, polishing paste and local anaesthesia. All the relevant articles and their references were analysed. The clinical manifestations of allergy to different dental materials based on different case reports were reviewed.

RESULTS

After reviewing the literature, we found that the dental material reported to cause most adverse reactions in patients is amalgam and the incidence of oral lichenoid reactions adjacent to amalgam restorations occur more often than other dental materials.

CONCLUSION

The most common allergic reactions in dental staff are allergies to latex, acrylates and formaldehyde. While polymethylmethacrylates and latex trigger delayed hypersensitivity reactions, sodium metabisulphite and nickel cause immediate reactions. Over the last few years, due to the rise in number of patients with allergies from different materials, the practicing dentists should have knowledge about documented allergies to known materials and thus avoid such allergic manifestations in the dental clinic.

Anaphylaxis to lidocaine with tolerance to articaine in a 12 year old girl

True allergic reactions to local anesthetics are extremely rare and constitute less than 1% of all reactions. In addition, many of those allergic reactions are caused by the preservative constituents of the local anesthetics. Here we report a 12 year old girl with anaphylaxis to lidocaine (an amide local anesthetic) on two occasions. The allergy was confirmed by positive skin prick test to the drug. Skin testing and challenge to another amide local anesthetic (articaine) were negative. Subsequently, its use was well tolerated in a dental procedure. Up to our knowledge, this is the first report of a patient who is allergic to lidocaine and tolerant to articaine.

Capture and documentation of coded data on adverse drug reactions: an overview

Allergic responses to prescription drugs are largely preventable, and incur significant cost to the community both financially and in terms of healthcare outcomes. The capacity to minimise the effects of repeated events rests predominantly with the reliability of allergy documentation in medical records and computerised physician order entry systems (CPOES) with decision support such as allergy alerts. This paper presents an overview of the nature and extent of adverse drug reactions (ADRs) in Australia and other developed countries, a discussion and evaluation of strategies which have been devised to address this issue, and a commentary on the role of coded data in informing this patient safety issue. It is not concerned with pharmacovigilance systems that monitor ADRs on a global scale. There are conflicting reports regarding the efficacy of these strategies. Although in many cases allergy alerts are effective, lack of sensitivity and contextual relevance can often induce doctors to override alerts. Human factors such as user fatigue and inadequate adverse drug event reporting, including ADRs, are commonplace. The quality of and response to allergy documentation can be enhanced by the participation of nurses and pharmacists, particularly in medication reconciliation. The International Classification of Diseases (ICD) coding of drug allergies potentially yields valuable evidence, but the quality of local and national level coded data is hampered by under-documenting and under-coding.

A new method of topical anesthesia by using anesthetic solution in a patch

INTRODUCTION

We investigated the effects of topical anesthesia of the oral mucosa by using an adhesive patch instilled with 2% lidocaine hydrochloride solution.

METHODS

The subjects were 20 healthy adult volunteers who gave written informed consent. Each patient was treated in a randomized crossover fashion with a hemostatic adhesive patch instilled with one of the following agents: 2% lidocaine hydrochloride with 12.5 μg/mL epinephrine, 2% lidocaine hydrochloride, 20% ethyl aminobenzoate, or physiological saline solution. A cotton ball containing 20% ethyl aminobenzoate was also tested. The adhesive patch or cotton ball was placed on the gingivobuccal fold of the maxillary right canine for 2 or 5 minutes. Then, a 33-gauge or 30-gauge needle was inserted to a depth of 2 mm. Insertion pain was evaluated with a visual analog scale (VAS) and a 4-level verbal rating scale immediately after needle removal. Efficacy of analgesia was calculated from the verbal rating scale.

RESULTS

The VAS was lower and the efficacy of analgesia was higher on 33-gauge needle insertion than on 30-gauge needle insertion in all treatments. The VAS was also significantly lower and the efficacy of analgesia was higher in the lidocaine groups than in the other groups. Adding epinephrine did not enhance the anesthetic effect of lidocaine hydrochloride.

CONCLUSIONS

Topical mucosal anesthesia with an adhesive patch containing 2% lidocaine hydrochloride solution is simple and may be more effective than conventional methods.

Inflammatory trigeminal nerve and tract lesions associated with inferior alveolar nerve anaesthesia

Inferior alveolar nerve blocks are commonly performed for dental anaesthesia. The procedure is generally safe with a low rate of complications. We report a patient with a reproducible, delayed-onset sensory deficit associated with contrast-enhancing lesions in the trigeminal nerve, pons and medulla following inferior alveolar nerve local anaesthesia. We propose that this previously undescribed condition is a form of Type IV hypersensitivity reaction.