Recent advances in topical anesthesia

Mirrors and toothaches: commonplace manipulations of non-auditory feedback availability change perceived speech intelligibility

This paper investigates the impact of two non-technical speech feedback perturbations outside the auditory modality: topical application of commercially-available benzocaine to reduce somatosensory feedback from speakers' lips and tongue tip, and the presence of a mirror to provide fully-detailed visual self-feedback. In experiment 1, speakers were recorded under normal quiet conditions (i.e., baseline), then again with benzocaine application plus auditory degradation, and finally with the addition of mirror feedback. Speech produced under normal and both feedback-altered conditions was assessed via naïve listeners' intelligibility discrimination judgments. Listeners judged speech produced under bisensory degradation to be less intelligible than speech from the un-degraded baseline, and with a greater degree of difference than previously observed with auditory-only degradation. The introduction of mirror feedback, however, did not result in relative improvements in intelligibility. Experiment 2, therefore, assessed the effect of a mirror on speech intelligibility in isolation with no other sensory feedback manipulations. Speech was recorded at baseline and then again in front of a mirror, and relative intelligibility was discriminated by naïve listeners. Speech produced with mirror feedback was judged as less intelligible than baseline tokens, indicating a negative impact of visual self-feedback in the absence of other sensory manipulations. The results of both experiments demonstrate that relatively accessible manipulations of non-auditory sensory feedback can produce speech-relevant effects, and that those effects are perceptible to naïve listeners.

Efficacy of topical anesthetics of lidocaine, benzocaine, and EMLA in reducing pain during inferior alveolar nerve block in schoolchildren: a randomized controlled trial

OBJECTIVES

This study aimed to evaluate the efficacy of 5% EMLA cream and 8% lidocaine gel in reducing pain during inferior alveolar nerve block (IANB) compared with 20% Benzocaine in children aged 6-10 years.

MATERIALS AND METHODS

This was a triple-blinded, randomized, parallel-group, active-controlled trial with three arms. 45 children were randomly assigned into 3 groups. Group 1: control group, 20% benzocaine gel (n = 15). Group 2: 8% lidocaine gel (n = 15). Group 3: 5% EMLA cream (n = 15). Each topical anesthetic was applied in an amount of 0.3 mL using a cotton swab for 2 min, followed by IANB administration. The following primary outcome measures were considered: pulse rate, the face, legs, activity, cry, consolability (FLACC) behavioral pain assessment scale, and the Wong-Baker FACES pain rating scale.

RESULTS

The mean score of the FLACC behavioral pain assessment scale in group 2 (2.20 ± 1.86) was slightly higher, but this result was not statistically significant p = (0.806). Regarding the Wong-Baker FACES pain rating scale scores, no statistically significant difference was noted between the study groups p = (0.593). After IANB administration, the mean pulse rate was higher in group 3 (102.40 ± 14.28). However, this difference was not statistically significant p = (0.351). In addition, the mean change of the pulse rate from the baseline to this time point was not statistically significant p = (0.638), indicating a smaller physiologic response to the painful stimulus.

CONCLUSION

8% lidocaine gel was not superior to 20% benzocaine nor 5% EMLA in reducing pain during IANB administration.

Lidocaine-Loaded Thermoresponsive Gel for Accelerated Wound Healing in Dry Socket and Oral Wounds

Dry socket, also known as alveolar osteitis, presents significant challenges in oral surgery because of severe pain and delayed wound healing. This study aims to address these challenges by developing and evaluating a lidocaine-loaded polyelectrolyte complex thermoresponsive gel (LG) designed to enhance wound healing and provide effective pain management in oral wounds. The thermoresponsive gel transitions from a liquid to a gel at body temperature, ensuring sustained contact with the wound site and prolonged release of lidocaine. The in vitro assessments, including cytotoxicity and wound scratch assays, demonstrated the biocompatibility and therapeutic potential of the LG formulation. Following this, palatal wounds were induced in rats, with healing monitored over a 14-days period. Histological analyses were conducted to assess tissue regeneration and inflammation. The results indicated that the LG formulation significantly improved wound closure rates, reduced inflammation, and accelerated epithelialization compared with control groups, primarily because of the high content of hyaluronic acid (HA). The synergistic effects of HA combined with the thermoresponsive properties of the gel facilitated faster healing. These findings suggest that LG is a promising therapeutic option for enhancing oral wound healing and effectively managing pain, particularly in conditions such as dry socket.

Lidocaine HCl-Loaded Polyelectrolyte Complex -Poloxamer Thermoresponsive Hydrogel: In Vitro- In Vivo Anesthetic Evaluations for Tooth Socket Wound Delivery

Local anesthesia is essential in dental practices, particularly for managing pain in tooth socket wounds, yet improving drug delivery systems remains a significant challenge. This study explored the physicochemical characteristics of lidocaine hydrochloride (LH) incorporated into a polyelectrolyte complex and poloxamer thermosensitivity hydrogel, assessing its local anesthetic efficacy in mouse models and its onset and duration of action as topical anesthetics in clinical trials. The thermoresponsive hydrogel exhibited a rapid phase transition within 1-3 minutes and demonstrated pseudo-plastic flow behavior. Its release kinetics followed Korsmeyer-Peppas, with 50% of biodegradation occurring over 48 h. In mouse models, certain thermogels showed superior anesthetic effects, with rapid onset and prolonged action, as evidenced by heat tolerance in tail-flick and hot plate models. In clinical trials, the LH-loaded thermoresponsive hydrogel provided rapid numbness onset, with anesthesia (Ton) beginning at an average of 46.5 ± 22.5 seconds and lasting effectively (Teff) for 202.5 ± 41.0 seconds, ranging from 120 to 240 seconds, indicating sustained release. These results highlight the promising properties of these formulations: rapid onset, prolonged duration, mucoadhesion, biodegradability, and high anesthesia effectiveness. This study demonstrates the potential for advancing local anesthesia across various medical fields, emphasizing the synergy between material science and clinical applications to improve patient care and safety.

Fresh Carrier for an Old Topical Local Anesthetic: Benzocaine in Nanostructured Lipid Carriers

Nanostructured lipid carriers (NLC) have emerged as innovative drug delivery systems, offering distinct advantages over other lipid-based carriers, such as liposomes and solid lipid nanoparticles. Benzocaine (BZC), the oldest topical local anesthetic in use, undergoes metabolism by pseudocholinesterase, leading to the formation of p-aminobenzoic acid, a causative agent for allergic reactions associated with prolonged BZC usage. In order to mitigate adverse effects and enhance bioavailability, BZC was encapsulated within NLC. Utilizing a 23 factorial design, formulations comprising cetyl palmitate (solid lipid), propylene glycol monocaprylate (liquid lipid), and Pluronic F68 as surfactants were systematically prepared, with variations in the solid/liquid lipid mass ratios (60:40-80:20%), total lipid contents (15-25%), and BZC concentrations (1-3%). The optimized formulation underwent characterization by dynamic light scattering, differential scanning calorimetry, Raman imaging, X-ray diffraction, small-angle neutron scattering, nanotracking analysis, and transmission electron microscopy (TEM)/cryo-TEM, providing insights into the nanoparticle structure and the incorporation of BZC into its lipid matrix. NLCBZC exhibited a noteworthy encapsulation efficiency (%EE = 96%) and a 1 year stability when stored at 25 °C. In vitro kinetic studies and in vivo antinociceptive tests conducted in mice revealed that NLCBZC effectively sustained drug release for over 20 h and prolonged the anesthetic effect of BZC for up to 18 h. We therefore propose the use of NLCBZC to diminish the effective anesthetic concentration of benzocaine (from 20 to 3% or less), thus minimizing allergic reactions that follow the topical administration of this anesthetic and, potentially, paving the way for new routes of BZC administration in pain management.

A mosquito proboscis-inspired cambered microneedle patch for ophthalmic regional anaesthesia

INTRODUCTION

One of the methods for pain management involves the use of local anesthesia, which numbs sensations in specific body regions while maintaining consciousness.

OBJECTIVES

Considering the certain limitations (e.g., pain, the requirement of skilled professionals, or slow passive diffusion) of conventional delivery methods of local anesthetics, developing alternative strategies that offer minimally invasive yet therapeutically effective delivery systems is of great concern for ophthalmic regional anesthesia.

METHODS AND RESULTS

In this study, a rapidly dissolving cambered microneedle (MNs) patch, composed of poly(vinylpyrrolidone) (PVP) and hyaluronic acid (HA) and served as a delivery system for lidocaine (Lido) in local anesthesia, was developed taking inspiration from the mosquito proboscis's ability to extract blood unnoticed. The lidocaine-containing MNs patch (MNs@Lido) consisted of 25 microneedles with a four-pronged cone structure (height: 500 μm, base width: 275 μm), arranged in a concentric circle pattern on the patch, and displays excellent dissolubility for effective drug delivery of Lido. After confirming good cytocompatibility, MNs@Lido was found to possess adequate rigidity to penetrate the cornea without causing any subsequent injury, and the created corneal pinhole channels completely self-healed within 24 h. Interestingly, MNs@Lido exhibited effective analgesic effects for local anesthesia on both heel skin and eyeball, with the sustained anesthetic effect lasting for at least 30 min.

CONCLUSIONS

These findings indicate that the mosquito proboscis-inspired cambered MNs patch provides rapid and painless local anesthesia, overcoming the limitations of conventional delivery methods of local anesthetics, thus opening up new possibilities in the treatment of ophthalmic diseases.

Evaluation of the Efficacy of a Customized Mucosal Vibrator in Alleviating Pain Perception Associated with Local Anesthesia Administration in Children Aged 6-10 Years

Introduction

Local anesthetics are used to alleviate pain, but the prick of the injection delivering anesthesia is known to cause anxiety and pain that affect dental treatment. The most difficult aspect of pediatric dentistry is minimizing discomfort while the intraoral local anesthetic is administered. This pain has been treated using physical, psychological, pharmacological, and combinations of these approaches. Recently, the idea of vibration, which is based on the gates control theory, has gained popularity as a way to reduce discomfort while local anesthesia (LA) is being administered.

Aim

The aim of this trial was to evaluate the efficacy of mucosal vibrators in children aged 6-10 years to alleviate pain associated with LA administration.

Materials and methods

A total of 60 patients aged 6-10 years requiring inferior alveolar nerve block were enrolled for this randomized, single-blind clinical trial. In group I, before and during LA administration, the customized mucosal vibrator was placed at the injection site. In group II, the topical local anesthetic gel was applied to the injection site prior to the administration of LA. Then, the local anesthetic solution was deposited using a disposable syringe needle on both groups. The pain was evaluated using the physiological scale (pulse rate and oxygen saturation), the subjective scale (Wong-Baker scale), and the objective scale [Face, Legs, Activity, Cry, Consolability (FLACC) scale] by an experienced assistant who was unaware of the procedure.

Results

A customized mucosal vibrator along with local anesthetic injections resulted in significantly less pain (p = 0.001*) when compared with the injections with topical anesthetic gel.

Conclusion

The results show that the customized mucosal vibrator is an effective and inexpensive means to reduce pain during LA administration.

How to cite this article

Tatiya N, Singh C, Surana P, et al. Evaluation of the Efficacy of a Customized Mucosal Vibrator in Alleviating Pain Perception Associated with Local Anesthesia Administration in Children Aged 6-10 Years. Int J Clin Pediatr Dent 2024;17(4):404-409.

Effectiveness of pre-injection use of cryoanesthesia as compared to topical anesthetic gel in reducing pain perception during palatal injections: a randomized controlled trial

Background

Palatal injections are often painful. We aimed to compare topical ice and 20% benzocaine gel for pre-injection anesthesia before greater palatine nerve block (GPNB) injections.

Methods

A randomized split-mouth clinical trial was conducted among patients aged 15-60-years needing bilateral GPNB injections. A total of 120 palatal sites from 60 patients were randomly allocated to Group A (topical ice) or Group B (20% benzocaine gel). Pain was evaluated using sound, eye, motor (SEM), and the visual analog scale (VAS) in both groups. Inferential analysis was performed using the Mann-Whitney U test.

Results

The mean age of the participants was 20.5 ± 3.9 years. The median VAS score for group A was 11 (Q1 - Q3: 5.25 - 21.75), which was slightly higher than the 10 (Q1 - Q3: 4.0 - 26.75) reported in group B. However, the difference was not statistically significant (P = 0.955). The median SEM score for group A and group B was 3.5 (Q1 - Q3: 3.0 - 4.0) and 4.0 (Q1 - Q3: 3.0 - 4.0), respectively, which was statistically insignificant (P = 0.869).

Conclusion

Using ice as a form of topical anesthetic for achieving pre-injection anesthesia before GPNB was as effective as 20% benzocaine gel.

An overview of local anesthetics in over-the-counter products

Over-the-counter (OTC) local anesthetics have historically been used to alleviate pain in several common conditions including toothache and sore throat. With a rise in chronic conditions and an aging population, there has been an increase in associated chronic pain-related disorders. Individuals with chronic pain often seek OTC treatments for quick and accessible pain relief. There are several common OTC local anesthetics, including benzocaine, lidocaine, and dibucaine, which are readily available to patients in several formulations. In order to appropriately advise patients on the use of local anesthetics, it is important to understand their key characteristics, including the mechanism of action, clinical properties, pharmacokinetics, clinical applications, and adverse reactions, which may occur.

Adhesive polydopamine-based photothermal hybrid hydrogel for on-demand lidocaine delivery, effective anti-bacteria, and prolonged local long-lasting analgesia

Considering the astonishing prevalence of localized pain affecting billions of patients worldwide, the development of advanced analgesic formulations or delivery systems to achieve clinical applicability is of great significance. In this study, an integrated PDA-based LiH@PDA@Ag@PAA@Gelatin system was designed for sustained delivery of lidocaine hydrochloride (LiH). By optimizing the preparation process and formulation of the hydrogel, the hydrogel exhibited superior mechanical properties, reversibility, adhesion strength, and self-healing attributes. Moreover, PDA@Ag nanoparticles were evenly dispersed within the hydrogel, and the optimized PDA@Ag@PAA@Gelatin showed a higher photothermal conversion efficiency than that of pure PDA. Importantly, LiH@PDA@Ag@PAA@Gelatin could effectively capture and eradicate bacteria through the synergistic interaction between near-infrared (NIR), PDA, Ag and LiH. In vitro and in vivo tests demonstrated that LiH@PDA@Ag@PAA@Gelatin exhibited higher drug delivery efficiency compared to commercial lidocaine patches. By evaluating the mechanical pain withdrawal threshold of the spared nerve injury (SNI) model in rats, it was proven that LiH@PDA@Ag@PAA@Gelatin enhanced and prolonged the analgesic effect of LiH. Furthermore, LiH@PDA@Ag@PAA@Gelatin induced by NIR possessed excellent on-demand photothermal analgesic ability. Therefore, this study develops a convenient method for preparing localized analgesic hydrogel patches, providing an important step towards advancing PDA-based on-demand pain relief applications.

State-Dependent Blockade of Dorsal Root Ganglion Voltage-Gated Na+ Channels by Anethole

Anethole is a phenolic compound synthesized by many aromatic plants. Anethole is a substance that humans can safely consume and has been studied for years as a biologically active molecule to treat a variety of conditions, including nerve damage, gastritis, inflammation, and nociception. Anethole is thought to carry out its biological activities through direct interaction with ion channels. Anethole is beneficial for neurodegenerative Alzheimer's and Parkinson's diseases. Nevertheless, nothing has been investigated regarding the effects of anethole on voltage-gated Na+ channels (VGSCs), which are major players in neuronal function. We used cultured dorsal root ganglion neurons from neonatal rats as a source of natively expressed VGSCs for electrophysiological studies using the whole-cell patch-clamp technique. Our data show that anethole interacts directly with VGSCs. Anethole quickly blocks and unblocks (when removed) voltage-activated Na+ currents in this preparation in a fully reversible manner. Anethole's binding affinity to these channels increases when the inactive states of these channels are populated, similar to lidocaine's effect on the same channels. Our data show that anethole inhibits neuronal activity by blocking VGSCs in a state-dependent manner. These findings relate to the putative anesthetic activity attributable to anethole, in addition to its potential benefit in neurodegenerative diseases.

Efficacy of Eutectic Mixture of Local Anesthetics (EMLA) Versus Ice as Topical Anesthetics Prior to Long Buccal Nerve Blocks: A Prospective Comparative Study

Background Dental extraction is one of the common procedures in the field of dentistry. However, fear and anxiety about local anesthetic injections are unavoidable for most patients. Topical anesthetics, distraction techniques, acupuncture, and the application of heat or cold have been used in practice to alleviate injection-related pain. The specific aim of this study was to compare the pain-relieving efficacy of eutectic mixture of local anesthetics (EMLA) vs. ice during the administration of a long buccal nerve block (LBNB) before dental extraction. Materials and Methods In total, 20 healthy adult patients who required bilateral mandibular posterior teeth extraction under local anesthesia were enrolled. The study was conducted in the Department of Oral and Maxillofacial Surgery, Saveetha Dental College and Hospitals, Chennai, from January 2023 to May 2023. It was a prospective split-mouth study in which each participant was divided into two groups according to the operative site: Group 1, which received a 5% EMLA cream, and Group 2, which received an application of ice before administration of LBNB. There was a one-week interval between the two interventions. The levels of pain and satisfaction were assessed using the visual analogue scale (VAS) and pain perception was evaluated by the sound, eye, motor (SEM) scale. Mann-Whitney U test was applied for the statistical analysis. Results The study included a total of 20 participants, with 14 being male and six being female. The mean age of the study population was 42 ± 15 years. When analyzing the pain scores using the VAS, it was found that Group 1 had a mean score of 2.4 ± 0.44, while Group 2 had a mean score of 3.0 ± 0.44. This difference between the two groups was statistically significant (P = 0.001). It was also found that the mean patient satisfaction score for Group 1 was 9.8 ± 0.22 and for Group 2 was 9.2 ± 0.40 which was statistically significant (p = 0.003). Similarly, Group 1 had a mean SEM score of 1.1 ± 0.1, while Group 2 had a mean SEM score of 1.30 ± 0.46 which was also statistically significant (P =0.016). Conclusion The study results revealed that EMLA has a significant advantage over ice in terms of lower levels of pain, more patient satisfaction, and higher comfort levels. EMLA can be considered the first choice of topical anesthetics, however, ice is recommended in resource-constrained dental set-ups as it is cost-effective.

Cryoanesthesia with ethyl chloride spray versus 5% lidocaine gel in alleviating oral local anesthetic injection pain for buccal anaesthesia: A randomized clinical (controlled) trial

Background

Numbing the area of oral mucosa with cold application prior to administration of regional anesthesia has been widely used by various dentists in alleviating pain caused by needle prick. Cryoanesthesia using Endo-ice as topical anesthesia has been studied as a replacement to prevail the fallibility of topical anaesthetics. This study aimed to evaluate and compare effectiveness of ethyl chloride spray with 5% lidocaine gel in alleviating buccal anesthesia injection pain.

Methods

Total of 90 outpatients were randomly divided into 3 groups as follows: Group 1 - cryotherapy with ethyl chloride at the anesthetic site preceding before administration of local anesthesia; Group 2 - topical application of 5% LIDOCAINE GEL preceding before administration of local anesthesia; and group 3 - control that did not receive any topical agent preceding before administration of local anesthesia. Visual analogue scale (VAS) was used to document pain immediately after injection prick.

Results

About comparison of pain scores, significant difference was found between group 1 (ethyl chloride) and group 2 (topical lidocaine) patients (P=0.001). For group 1, about 15 (50%) patients suffered from mild pain, followed by 14 (46.67%) patients suffering from moderate pain. However, majority of the 21 (70%) patients in group 2 suffered from moderate pain. All the patients in group 3 suffered from severe pain.

Conclusion

Importance of alleviating fear of needle injection phobia amongst patients is of paramount importance. Ethyl chloride was found to be more effective than topical lidocaine in alleviating needle injection pain before administration of local anesthetic injection.

Comparative Assessment of Pain during Infiltration by a Two-stage Infiltration Technique: A Double-blind Clinical Trial

AIM

The aim of this study was to assess and compare the pain during infiltration by a modified two-stage local anesthetic infiltration technique under topical anesthesia (TA).

MATERIALS AND METHODS

In this cross-over double-blind study, 30 volunteers participated, where two groups were given single-stage infiltration and the other two had two-stage infiltrations. Depending upon the infiltration technique (one- or two-stage) and the use of TA, the patients were randomly divided into four groups. Local anesthesia (LA) was administered by infiltration into the mucobuccal fold of the maxillary central incisor, and the pain perceived during the infiltration in each group was recorded. The volunteers were recalled after 24 hours to assess the tenderness at the injection site. The volunteers were recalled 2 weeks after infiltration for the subsequent groups to assess the pain for this cross-over study.

RESULTS

A statistically significant difference was observed in the pain perceived when TA was used and when the infiltration was done in two stages. Regarding the pain at the site of injection after 24 hours, no significant difference was observed among the volunteers.

CONCLUSION

Topical anesthesia was effective in reducing the pain of injection when compared to placebo. The pain of injection is further reduced with a two-stage infiltration technique after TA application.

CLINICAL SIGNIFICANCE

Topical anesthesia can be used routinely before infiltration, and LA infiltration injections are less painful if administered in two stages.

The Clinical Efficacy of EMLA as a Topical Anesthetic Agent Instead of Palatal Injection During Maxillary Dental Extractions: A Randomized Controlled Trial

Background

Even after the invention of the modern injection techniques, palatal injection still remains a painful experience for patients, and this pain is attributed to the presence of rich nerve complement and displacement of tightly adherent palatal mucosa during anesthesia.

Aim

To check the clinical efficacy of EMLA as a topical anesthetic agent instead of palatal injection during maxillary dental extractions.

Methodology

The trial includes a total of 102 participants, in whom maxillary molar extractions were indicated, were randomly divided into the experimental group (eutectic mixture of local anesthesia (EMLA) topical application was used along with buccal injection) and control group (palatal injection along with buccal injection). Pain perception during extraction was recorded using the visual analog scale (VAS).

Results

Mean VAS score for 'injection' in control group patients was 5.2 ± 2.08 in contrast to no pain in experimental group. In experimental group, mean VAS score on 'probing' was 0.92 ± 1.50. VAS score on 'extraction' in EMLA group was little higher though the difference was not statistically significant. The overall experience using Liekert's scale was higher in experimental group (4.0 ± 0.76) as compared to (3.3 ± 0.82) in control group leading to higher overall satisfaction among patients who underwent extraction in the experimental group.

Conclusion

EMLA application produced a satisfactory level of anesthesia in the palatal tissue when compared with the palatal injection.

Effectiveness and Tolerability of a New Formulation of a Topical Anesthetic in Reduction of Pain and Parents’ Satisfaction in Pediatric Dentistry

The aim of the present study was to test a new topical anesthetic gel with a different formulation (10% lidocaine, 10% prilocaine) to analyze its effectiveness in pain control, during the subsequent injection of local anesthetic, and the presence of any side effects. Methods: The study’s research design was a randomized controlled clinical trial on 300 children, aged 5–8 years, divided into two groups, each of 150 patients, according to pre-injection procedures (presence or absence of topical anesthesia). The injection pain was analyzed using the Wong-Baker Faces Pain Rating Scale (PRS) and the Face, Legs, Activity, Cry, Consolability Scale (FLACC). At the end of the procedures, patients’ parents’ satisfaction was recorded. The data were analyzed using the Student’s T test, Mann–Whitney U test and Chi-square test. Results: There were statistically significant differences between the two groups both in the PRS and FLACC ratings. Both in subjective and objective pain evaluations, significantly higher pain ratings were observed in the group without topical anesthesia. There was also a statistically significant difference in terms of patients’ parents’ judgment, as in the group with the use of topical anesthetic the level of parental satisfaction is statistically higher. Conclusion: The experimental anesthetic has proved very effective in its use as a topical gel in both pain measurement scales, thus validating its use on the oral mucosa, for its pharmacological and psychological effect, in the total absence of local and systemic side effects.

The Effect of Dentin Contamination by Topical Anesthetics on Micro-Shear Bond Strength: An In Vitro Experiment

Topical anesthetics are commonly used to minimize pain and anxiety during dental procedures. Research is scarce on the influence of topical anesthetics on bond strength. Thus, this research evaluated the effect of dentin contamination by topical anesthetic solution and gel on the micro-shear bond strengths of etch-and-rinse and self-etch bonding systems. Ninety transversally hemi-sectioned dentin discs were prepared and randomly assigned to three groups: no contamination (control group), contamination with topical anesthetic solution (Xylonor spray, Septodont), and contamination with topical anesthetic gel (Xylonor gel, Septodont). Each contamination group was subdivided into two subgroups (n = 15) based on whether the adhesive system was etch-and-rinse (Optibond Solo Plus, Kerr) or self-etch (Optibond XTR, Kerr). Tygon tubes with resin composite (Filtek Z350 XT, 3M ESPE) were placed on each surface and light cured. After 24 h, a universal testing machine was used to measure micro-shear bond strength (MPa). Furthermore, nine additional specimens of non-contaminated and contaminated dentin were prepared and scanned by a scanning electron microscope. The data of micro-shear bond strength were analyzed using two-way ANOVA, and narrative analysis was used to qualitatively interpret visual data of the micro-morphology of dentin from the scanning electron microscope. No significant differences in micro-shear bond strength among different contamination groups and adhesive systems were found (p > 0.05). The results are supported by micro-morphology of the treated dentin surfaces and modes of failure, as the micro-morphology was similar among contamination and control groups. There was no significant impact of topical anesthetic forms and dentin bonding systems on the micro-shear bond strength, which was supported by the micro-morphology from a scanning electron microscope.

Herbal topical anesthetics in dentistry: an exploratory review

Topical anesthetics are routinely used in dental practice for various purposes. They are usually available at higher dosages and have serious potential adverse reactions, such as seizures, anaphylaxis, and acquired methemoglobinemia. To date, the scope of application of herbal plants and their extracts, which have medicinal properties, has been elaborated in the field of dentistry. The growing interest in herbal medication can be attributed to the increased safety profile of herbal agents, in contrast to synthetic preparations that have a higher risk of systemic complications. Herbal preparations can induce topical anesthesia with minimal side effects. Recently, many studies have reported the use of topical herbal preparations. The current review aimed to evaluate data from various articles comparing the capacity of herbal topical anesthetic formulations and conventional synthetic anesthetics in reducing pain perception when used as local anesthesia before dental procedures.

The 1064-nm Nd: YAG Photobiomodulation vs. 20% Benzocaine Topical Gel in Inducing Mucosal Anesthetic Effect: A Double-Blind Randomized Clinical Trial

The periapical local anesthetic injection may be associated with fear of needles and pain administration. Dental topical anesthetic agents can help to reduce pain perception; however, adverse events can occur. To investigate the efficacy of 1064-nm photobiomodualtion (PBM) in inducing mucosal anesthesia delivered with a flat-top hand-piece compared to 20% Benzocaine topical anesthetic gel, sixty healthy patients were randomly allocated (1:1) to either 20% benzocaine topical gel + placebo laser (T group) or PBM + placebo gel (L group). The 1064-nm Nd:YAG laser was employed and is associated with a novel flat-top hand piece. The applied operational parameters were 0.5 W, 10 Hz, 100 µs pulse width, and 30 J/cm2 for one-minute single application time. The enrolled subjects were asked to assess pain intensity at the time of anesthetic injection with a Visual Analog Scale. Taking into consideration taste, undesirable numbness, and overall satisfaction, the patients were asked to rate their experiences according to a verbal rating scale. Statistical analysis showed no statistically significant difference between the T and L Groups for pain ratings (p = 0.0596). The L Group displayed significantly higher ratings than T Group for taste, undesirable numbness, and overall satisfaction (p < 0.001). The 1064-nm PBM delivered by flat-top hand piece is effective in inducing mucosal anesthesia, eliminating the adverse side-effects of the conventional topical anesthetic gel.

Topical Anesthesia in Pediatric Dentistry: An Update

Topical anesthetics are very important tools for improving comfort in any dental procedure in children. different methods, techniques of achieving topical anesthesia are reported in the literature. The present narrative review focuses on explaining different types of topical anesthesia with a special focus on pediatric dentistry. How to cite this article: Tirupathi S, Rajasekhar S. Topical Anesthesia in Pediatric Dentistry: An Update. Int J Clin Pediatr Dent 2022;15(2):240-245.

A high-dosage microneedle for programmable lidocaine delivery and enhanced local long-lasting analgesia

Considering the staggering global prevalence of local pain affecting hundreds of million individuals, it is of great significance to develop advanced dosage forms or delivery systems for analgesic therapy to fulfill clinical applicability. In this study, a hydrogel microneedles (MNs) system made out of gelatin-methacryloyl (GelMA) was designed to deliver lidocaine hydrochloride (LiH) in a sustained manner, and the drug loading capacity of the GelMA MNs was increased considerably by using the backing layer reservoir. The in vitro and in vivo tests showed that the fabricated GelMA MNs are strong enough for reliable skin application, and achieve high drug delivery efficiency as compared with the commercial lidocaine patches. The Spared-nerve injury (SNI) model of rats was also prepared to test behavioral pain sensitivity in response to mechanical stimuli, which proved that the LiH/GelMA MNs can enhance and prolong the anesthetic effect of LiH. In addition, with biosafety evaluation in rats, the MNs treated site restored to normal appearance within several hours of application and no dermatosis-related side effects or behavior disorders were observed during the experiment. Together these results indicated that the use of GelMA MNs for transdermal delivery of LiH is an effective, safe and simple treatment method to provide a better choice for local long-lasting analgesia.

Effects of different topical anesthetics on pain from needle insertion and injection, and the influence of anxiety in patients awaiting endodontic treatment

Objectives

This study aimed to evaluate the effects of 5% lidocaine and 2.5% lidocaine/2.5% prilocaine topical anesthetic on pain during needle insertion and infiltration injection in the labial mucosa of anterior maxillary teeth, and to assess the relationship between patients’ anxiety and pain scores.

Materials and Methods

The Modified Dental Anxiety Scale questionnaire was applied and recorded. Patients were randomly divided into 4 groups (n = 30), as follows: G1 group: 5% lidocaine and placebo for 1 minute, G2 group: 2.5% lidocaine/2.5% prilocaine and placebo for 1 minute, G3 group: 5% lidocaine and placebo for 3 minutes, and G4 group: 2.5% lidocaine/2.5% prilocaine and placebo for 3 minutes. Before the application of topical anesthesia, one side was randomly selected as the topical anesthesia and the contralateral side as the placebo. The pain levels were measured with Visual Analog Scale (VAS) immediately after needle insertion and injection and were compared. The correlation between anxiety and pain scores was analyzed.

Results

Administration of 5% lidocaine for 1 minute had significantly higher pain scores for both insertion and infiltration injection than the other groups (p < 0.05). There was a significant moderate positive correlation between dental anxiety and the injection-induced VAS pain score in the placebo side in all groups (p < 0.05).

Conclusions

Topical anesthetics significantly reduced the pain caused by both needle insertion and injection pain in comparison to the placebo side. The pain scores of patients with dental anxiety were lower on the topical anesthesia compared to the placebo side.

Trial Registration

Thai Clinical Trials Registry Identifier: TCTR20201217002

The combined effect of extraoral vibratory stimulus and external cooling on pain perception during intra-oral local anesthesia administration in children: a systematic review and meta-analysis

This study aimed to assess the combined use of extraoral vibratory stimulation and extraoral cooling in reducing the pain (subjective and objective) of dental local anesthesia administration in children.

PubMed, Cochrane Central Register of Controlled Trials, and Ovid SP databases were searched up to July 2021. Article titles were screened and full-text evaluations of the selected articles were performed. Finally, seven studies (391 children, aged 4 – 12 years) were included in this qualitative and quantitative analysis. The pooled data determined the combined effect of extraoral vibration and extraoral cooling as a single measure. Extraoral vibration or cooling alone were not compared. The measured primary and secondary outcomes were pain perception and subjective and objective pain, respectively. When compared with the control, extraoral vibration and cooling resulted in significant differences in the mean combined data for the variables, pain perception, and pain reaction. Children’s subjective pain as measured by pain scores were reduced when extraoral vibration and cooling was used during local anesthesia administration (mean difference -3.52; 95% confidence interval [-5.06 - 1.98]) and objective pain (mean difference -1.46; 95% confidence interval [-2.95 - 0.02] ; mean difference -1.93; 95% confidence interval [-3.72 - 0.14]).

Within the confines of this systematic review, there is low-quality evidence to support the use of combined extraoral vibration and cooling for reducing pain (subjective and objective) during intraoral local anesthesia administration in children.

Effectiveness of lidocaine spray on radial arterial puncture pain: A randomized double-blind placebo controlled trial

OBJECTIVE

Radial arterial puncture is a painful procedure. The aim of this study was to evaluate the effect of lidocaine spray (10%) on pain associated with radial artery blood withdrawal for arterial blood gas analysis.

METHODS

This randomized, controlled, double-blind study was performed between December 2018 and September 2019. Before radial arterial puncture, 10% lidocaine or placebo spray was applied to each patient by the attending physician, who was blinded with regard to random assignment. The spray was administered six times on the site from a distance of 5 cm. After waiting for 5 min, a radial arterial puncture was performed routinely. The pain levels of patients during radial arterial puncture and 5 min after puncture were evaluated with the visual analog scale (VAS). The Wilcoxon test was used to compare pain scores during puncture.

RESULTS

The research was performed with 67 patients (34 patients in the lidocaine group, 33 patients in the placebo group) who were admitted to the emergency department and required ABG analysis. Forty-three patients were men, and 24 were women. The ages of the patients ranged between 19 and 86 years, and the mean (± standard deviation) age was 56.3 ± 16.6 years. Pain levels, as measured by VAS, were significantly lower in the lidocaine group (24.00 mm IQR:[14.75-33.75]) compared with the placebo group (33.00 mm IQR:[22.00-61.50]) during radial arterial puncture (p = 0.011).

CONCLUSIONS

The level of pain perceived during radial arterial puncture was significantly lower in those who were administered lidocaine spray. Lidocaine spray application can be used in pain management related to radial arterial puncture.

Comparative Evaluation of the Effectiveness of Different Pain-alleviating Methods before Local Anesthetic Administration in Children of 6 to 12 Years of Age: A Clinical Study

Background and aim of the study

Pediatric patients are apprehensive regarding having dental treatment mainly because of painful local anesthetic (LA) injections. Various techniques like transcutaneous electrical nerve stimulation (TENS), topical anesthetic agents, and vibrator device are introduced to reduce discomfort before LA administration. Therefore, the present study aimed to compare and evaluate the effectiveness of TENS, 2% lignocaine gel, eutectic mixture of lignocaine and prilocaine (EMLA), and vibrating device before LA injections in alleviating pain in pediatric patients.

Materials and methods

Sixty healthy children aged 6 to 12 years who required LA injections for dental procedures were selected and divided into four groups with 15 patients in each group. Wong–Baker's facial pain rating scale (WBFPRS) and face, legs, activity, cry, and consolability scale (FLACC) are used for pain perception which are tabulated, and statistically analyzed.

Results

The test results demonstrated that the TENS group has shown the least mean WBFPRS and FLACC score, followed by vibrator devices, EMLA gel, and lignocaine gel.

Conclusion

The newly introduced TENS apparatus showed encouraging results, hence can be used as a safe and reliable technique to be used in pediatric dentistry.

How to cite this article

Patil SB, Popali DD, Bondarde PA, et al. Comparative Evaluation of the Effectiveness of Different Pain-alleviating Methods before Local Anesthetic Administration in Children of 6 to 12 Years of Age: A Clinical Study. Int J Clin Pediatr Dent 2021;14(4):447–453.

Formulation development and evaluation of lidocaine hydrochloride loaded in chitosan-pectin-hyaluronic acid polyelectrolyte complex for dry socket treatment

The main purpose of this study was to assess a lidocaine hydrochloride-loaded chitosan-pectin-hyaluronic polyelectrolyte complex for rapid onset and sustained release in dry socket wound treatment. Nine formulations (LCs) of lidocaine hydrochloride (LH) loaded into a chitosan–pectin–hyaluronic polyelectrolyte complex (PEC) were assessed using full factorial design (two factors × three levels). The formulations ranged between 4 and 10% w/w LH and 0.5–1.5% w/w HA. The following physicochemical properties of LCs were characterized: size, zeta potential, % entrapment efficiency, viscosity, mucoadhesiveness, % drug release, morphology, storage stability, and cytotoxicity. The particle size, zeta potential, % EE, viscosity, and % mucoadhesion increased with increasing LH and HA concentrations. Rapid release of LH followed a zero-order model, and a steady-state percentage of the drug was released over 4 h. LCs were found to be non-cytotoxic compared to LH solution. LH loaded into PEC demonstrated appropriate characteristics—including suitable rate of release—and fit a zero-order model. Furthermore, it was not cytotoxic and showed good stability in a high-HA formula, making it a promising candidate for future topical oral formulations.

Tongue-Tie children with a severe Hazelbaker score or difficult breastfeeding greatly benefit from frenotomy or frenuloplasty with/without anaesthesia - First do or do no harm?

Tongue-tie (ankyloglossia) is a relatively common congenital anomaly characterised by an abnormally short lingual fraenulum, causing limitation of tongue mobility. There have been immense controversies regarding diagnosis, clinical significance and management of such condition hitherto. Although most tongue-tie babies are asymptomatic without feeding difficulties, operative corrections may be necessary in some cases to improve their breastfeeding. Using a meta-narrative reviewing study design, the aim of this concise review was to demonstrate the current evidences for surgical indications, optimal type and timing, and functional improvement from tongue-tie surgery. We reviewed and discussed the included evidences based on five topics: (1) basic sciences, (2) clinical equipoise, (3) anaesthesia during childhood, (4) evidence-based practice and surgical meta-analyses, and (5) appropriate patient assessment in routine paediatric practice.

Application of Quantitative NMR Spectroscopy to the Quality Evaluation of Diclofenac Gargles as Hospital Preparations

Hospital preparations are frequently prepared in Japanese hospitals when ready-made formulations to meet patients' needs are unavailable. Although the quality of hospital preparations have to be ensured for efficacy and safety, such quality evaluation tends to be insufficient mainly due to lack of manpower and experimental environments in hospitals. In this paper, we investigated the applicability of quantitative (q)NMR spectroscopy to the quality control of diclofenac gargles as examples of hospital preparations, as it has various merits for the quantitative analysis of mixtures in solutions. Diclofenac gargles are composed of diclofenac, tranexamic acid, and lidocaine, and are used for the pain relief of stomatitis induced by cancer chemotherapy. Aliquots of the gargles, which were prepared five times, were mixed with dimethylsulfone as an internal standard, followed by qNMR measurements. Water signal suppression was achieved using a pulse program, water suppression enhanced through T₁ effects, because the pulse program was superior to other ones such as presaturation and one-dimensional nuclear Overhauser effect spectroscopy in terms of quantitativeness. Concentrations of the three medicinal ingredients were simultaneously determined based on the signals selected by considering the spectral separation and the quantitativeness. Consequently, the gargles were found to be prepared with constant quality, and were stable at room temperature for at least four weeks. qNMR is considered to be potentially useful for the quality control of various hospital preparations because of minimal sample pretreatments, lack of need of calibration curves, and its comprehensive detection abilities.

Polymer-Based Carriers in Dental Local Healing-Review and Future Challenges

Polymers in drug formulation technology and the engineering of biomaterials for the treatment of oral diseases constitute a group of excipients that often possess additional properties in addition to their primary function, i.e., biological activity, sensitivity to stimuli, mucoadhesive properties, improved penetration of the active pharmaceutical ingredient (API) across biological barriers, and effects on wound healing or gingival and bone tissue regeneration. Through the use of multifunctional polymers, it has become possible to design carriers and materials tailored to the specific conditions and site of application, to deliver the active substance directly to the affected tissue, including intra-periodontal pocket delivery, and to release the active substance in a timed manner, allowing for the improvement of the form of application and further development of therapeutic strategies. The scope of this review is polymeric drug carriers and materials developed from selected multifunctional groups of natural, semi-synthetic, and synthetic polymers for topical therapeutic applications. Moreover, the characteristics of the topical application and the needs for the properties of carriers for topical administration of an active substance in the treatment of oral diseases are presented to more understand the difficulties associated with the design of optimal active substance carriers and materials for the treatment of lesions located in the oral cavity.

Effect of epinephrine on the absorption of lidocaine following application to the oral mucosa in rats

Background

We investigated the role of epinephrine in prolonging the localization of lidocaine on the oral mucosa and inhibiting its absorption in the blood of rats.

Methods

We used 7–8-week-old pathogen-free Wistar male rats (n = 128) for our study. We divided them into the control group administered with ¹⁴C-labeled lidocaine hydrochloride gel only and the study group administered with ¹⁴C-labeled lidocaine hydrochloride gel with epinephrine. The medications were administered in the palatal mucosa of the rats. The amount of mucosa, palatine bone, and serum lidocaine was measured by radioactivity using a liquid scintillation counter and was observed using autoradiograms.

Results

Initially, there was no significant difference in the lidocaine levels between the lidocaine and lidocaine with epinephrine groups in the palatal mucosa (751.9 ± 133.8 vs. 669.8 ± 101.6 ng/mg [2 min]). After 4 min, the values were significantly lower in the lidocaine with epinephrine group (1040.0 ± 142.8 vs. 701.2 ± 109.0 ng/mg [20 min]). After 40 min, the lidocaine level became significantly higher in the lidocaine with epinephrine group (586.8 ± 112.4 vs. 1131.3 ± 155.2 ng/mg [40 min]). Similar results were observed in the palatine bone and serum.

Conclusion

Epinephrine prolonged the localization of lidocaine applied to the mucosa and inhibited its absorption into the bloodstream of rats. Clinical studies are required to evaluate the use of epinephrine-containing topical anesthetics on the oral mucosa.

A Review of Evidence-Based Recommendations for Pericoronitis Management and a Systematic Review of Antibiotic Prescribing for Pericoronitis among Dentists: Inappropriate Pericoronitis Treatment Is a Critical Factor of Antibiotic Overuse in Dentistry

This work provides a narrative review covering evidence-based recommendations for pericoronitis management (Part A) and a systematic review of antibiotic prescribing for pericoronitis from January 2000 to May 2021 (Part B). Part A presents the most recent, clinically significant, and evidence-based guidance for pericoronitis diagnosis and proper treatment recommending the local therapy over antibiotic prescribing, which should be reserved for severe conditions. The systematic review includes publications analyzing sets of patients treated for pericoronitis and questionnaires that identified dentists’ therapeutic approaches to pericoronitis. Questionnaires among dentists revealed that almost 75% of them prescribed antibiotics for pericoronitis, and pericoronitis was among the top 4 in the frequency of antibiotic use within the surveyed diagnoses and situations. Studies involving patients showed that antibiotics were prescribed to more than half of the patients with pericoronitis, and pericoronitis was among the top 2 in the frequency of antibiotic use within the monitored diagnoses and situations. The most prescribed antibiotics for pericoronitis were amoxicillin and metronidazole. The systematic review results show abundant and unnecessary use of antibiotics for pericoronitis and are in strong contrast to evidence-based recommendations summarized in the narrative review. Adherence of dental professionals to the recommendations presented in this work can help rapidly reduce the duration of pericoronitis, prevent its complications, and reduce the use of antibiotics and thus reduce its impact on patients’ quality of life, healthcare costs, and antimicrobial resistance development.

Perioperative Pain Management and Opioid Stewardship: A Practical Guide

Surgical procedures are key drivers of pain development and opioid utilization globally. Various organizations have generated guidance on postoperative pain management, enhanced recovery strategies, multimodal analgesic and anesthetic techniques, and postoperative opioid prescribing. Still, comprehensive integration of these recommendations into standard practice at the institutional level remains elusive, and persistent postoperative pain and opioid use pose significant societal burdens. The multitude of guidance publications, many different healthcare providers involved in executing them, evolution of surgical technique, and complexities of perioperative care transitions all represent challenges to process improvement. This review seeks to summarize and integrate key recommendations into a "roadmap" for institutional adoption of perioperative analgesic and opioid optimization strategies. We present a brief review of applicable statistics and definitions as impetus for prioritizing both analgesia and opioid exposure in surgical quality improvement. We then review recommended modalities at each phase of perioperative care. We showcase the value of interprofessional collaboration in implementing and sustaining perioperative performance measures related to pain management and analgesic exposure, including those from the patient perspective. Surgery centers across the globe should adopt an integrated, collaborative approach to the twin goals of optimal pain management and opioid stewardship across the care continuum.

Randomised controlled trial of a microneedle patch with a topical anaesthetic for relieving the pain of dental injections

OBJECTIVES

To determine whether a microneedle patch combined with 5% topical lidocaine reduces dental injection pain more than a patch without microneedles combined with 5% topical lidocaine.

METHODS

This proof of principle randomised, two-treatment, double-blind, crossover split-unit design study in 16 healthy participants investigated levels of perceived pain from 3 increasing pain provoking challenges, when topical 5% lidocaine dental gel was applied to the oral mucosa with a microneedle patch and a patch with no microneedles, prior to infiltration with local anaesthesia on 2 visits. Pain was assessed by visual analogue scale (VAS) and 4-point verbal rating scale (VRS).

RESULTS

15 participants completed the study. Mean pain scores, lower at buccal sites, increased in both groups across challenges 1-3: Test palatal 5.1, 11.9, 26.8; buccal 0.7, 2.8, 18.3; Control palatal 12.3, 18.7, 39.5; buccal 4.0, 6.9, 30.6. The microneedle patch plus lidocaine significantly lowered VAS pain scores at both sites for all challenges, the biggest mean difference seen palatally after challenge 3 (12.7, p < 0.001). VRS pain scores were also significantly reduced for test compared to control for all 3 challenges (p = 0.014). Buccal scores favoured the microneedle patch, significantly for pain challenge 3 (p = 0.025). No adverse events occurred.

CONCLUSIONS

Prior oral application of a microneedle patch combined with 5% topical lidocaine gel reduced the pain experienced from dental infiltration. Microneedle patch use in the dental setting offers the prospect of improving degree and depth of anaesthesia from topically applied anaesthetic gel, without itself causing any pain.

CLINICAL SIGNIFICANCE

Dental injections are associated with fear and anxiety. Application of a microneedle patch, combined with topical anaesthetic, to the oral mucosa prior to delivery of the injection reduces the pain from this dental procedure. This novel technique may allay patients' apprehension of local anaesthesia and improve quality of life outcomes.

Co-Application of Eugenol and QX-314 Elicits the Prolonged Blockade of Voltage-Gated Sodium Channels in Nociceptive Trigeminal Ganglion Neurons

Local anesthetics (LAs) can completely block nociception by inhibiting voltage-gated sodium channels (VGSCs), and thus, blocking action potentials (APs) within sensory neurons. As one of the several LAs, eugenol is used for dental pain treatment. It reportedly features multiple functions in regulating diverse ion channels. This study aimed to investigate the long-lasting analgesic effect of eugenol alone, as well as that of the combination of eugenol as a noxious-heat-sensitive transient receptor potential vanilloid 1 (TRPV1) channel agonist and a permanently charged sodium channel blocker (QX-314), on neuronal excitability in trigeminal ganglion (TG) neurons. Eugenol alone increased inward current in a dose-dependent manner in capsaicin-sensitive TG neurons. Eugenol also inhibited the VGSC current and AP. These effects were reversed through wash-out. The combination of eugenol and QX-314 was evaluated in the same manner. The combination completely inhibited the VGSC current and AP. However, these effects were not reversed and were continuously blocked even after wash-out. Taken together, our results suggest that, in contrast to the effect of eugenol alone, the combination of eugenol and QX-314 irreversibly and selectively blocked VGSCs in TG neurons expressing TRPV1.

Topical anesthesia for stainless steel crown tooth preparation in primary molars: a pilot study

Background

Placement of full-coverage restorations such as stainless steel crowns (SSCs) for pulpectomy treated primary molars is essential for successful outcomes. The tooth preparation process for SSCs can cause discomfort to gingival tissues since the crown should be seated 1 mm subgingivally. The purpose of this prospective trial was to compare the effectiveness of subgingival and transmucosal application of topical anesthetics on dental pain during SSC tooth preparation among 6- to 8-year-old children.

Methods

A consecutive sample of 27 children, aged 6-8 years, who required an SSC after pulp therapy in primary molars were randomly divided into three groups. Group A received infiltration anesthesia before tooth preparation for SSC placement, whereas in Group B and C, only topical anesthesia was applied subgingivally and transmucosally. Wong-Bakers Faces pain rating scale (WBFPS) scores were recorded after tooth preparation. Faces, Legs, Activity, Cry and Consolability (FLACC) scores were evaluated by two blinded and calibrated investigators through video recordings of the patient during tooth preparation. Data were tabulated, and inter-group comparisons were performed using the Kruskal-Wallis and analysis of variance tests.

Results

Out of the 27 participants, 48% were boys and 52% were girls, with an overall mean age of 6.83 years. Group A showed the least pain scores according to both the scales, followed by Group B and Group C. The pain intensity was statistically significant on both the pain scales with P = 0.003 for FLACC and P < 0.001 for WBFPS.

Conclusion

Subgingival application of topical anesthesia reduced pain to a certain extent but not as effectively as infiltration anesthesia during SSC tooth preparation in primary molars. Transmucosal application of topical anesthesia did not reduce discomfort when compared to the other two interventions.

Efficacy of Er,Cr:YSGG laser-assisted delivery of topical anesthesia in the oral mucosa

OBJECTIVE

Lasers which can reduce epithelium thickness will enhance the penetration of topical drugs. To date, no study has assessed the efficacy of this technique in the oral mucosa. The aim of this study was the evaluation of efficacy of this technique in increasing the effect of topical anesthesia in the oral mucosa.

MATERIALS AND METHODS

On 20 volunteers, half of the lower lip mucosa was irradiated with Er,Cr:YSGG laser with 2780 nm wavelength and 1.3 J/cm² energy for 1 min; then, topical lidocaine was applied on the entire lower lip mucosa. After 5 min, a 27-gauge needle was inserted to each half of the lip mucosa, and the length of the needle inserted into the mucosa without feeling pain was considered the depth of insertion. This measurement was repeated every 15 min for 1 h.

RESULTS

The mean depth of anesthesia at the control side was 6.95 ± 2.43, 8.45 ± 4.05, 6.5 ± 3.00, and 3.85 ± 2.08 mm at 5, 20, 35, and 60 min, respectively. These values at the test side were 12.25 ± 5.42, 13.25 ± 5.02, 11.4 ± 5.03, and 9.10 ± 5.84 mm, respectively. According to repeated-measures ANOVA, the effect of the type of the treatment on the depth of insertion was significant (P < 0.001).

CONCLUSIONS

The results showed that irradiation of Er,Cr:YSGG laser before the topical application of the anesthetic agents on the oral mucosa increases their efficacy.

CLINICAL RELEVANCE

Topical anesthesia is used to enhance dental procedures painlessly, but there is controversy in their efficacy. Laser-assisted drug delivery to the oral mucosa can enhance their efficacy.

Prilocaine-Induced Methemoglobinemia

Local anesthetics are used to anesthetize surface areas in several procedures. The history of anesthesia exposure has been established as an important factor for correct diagnosis. When they are used excessively, some systemic side effects such as methemoglobinemia, respiratory failure, cardiovascular arrhythmias, or neurological manifestations may occur. Methemoglobinemia which usually presents with nonspecific symptoms is a serious entity. It is a rare but severe side effect of anesthetics. We herein present a case of methemoglobinemia due to local anesthesia with prilocaine.

Inhibition of Fast Nerve Conduction Produced by Analgesics and Analgesic Adjuvants-Possible Involvement in Pain Alleviation

Nociceptive information is transmitted from the periphery to the cerebral cortex mainly by action potential (AP) conduction in nerve fibers and chemical transmission at synapses. Although this nociceptive transmission is largely inhibited at synapses by analgesics and their adjuvants, it is possible that the antinociceptive drugs inhibit nerve AP conduction, contributing to their antinociceptive effects. Many of the drugs are reported to inhibit the nerve conduction of AP and voltage-gated Na⁺ and K⁺ channels involved in its production. Compound action potential (CAP) is a useful measure to know whether drugs act on nerve AP conduction. Clinically-used analgesics and analgesic adjuvants (opioids, non-steroidal anti-inflammatory drugs, ₂-adrenoceptor agonists, antiepileptics, antidepressants and local anesthetics) were found to inhibit fast-conducting CAPs recorded from the frog sciatic nerve by using the air-gap method. Similar actions were produced by antinociceptive plant-derived chemicals. Their inhibitory actions depended on the concentrations and chemical structures of the drugs. This review article will mention the inhibitory actions of the antinociceptive compounds on CAPs in frog and mammalian peripheral (particularly, sciatic) nerves and on voltage-gated Na⁺ and K⁺ channels involved in AP production. Nerve AP conduction inhibition produced by analgesics and analgesic adjuvants is suggested to contribute to at least a part of their antinociceptive effects.

Oral Pain in the Cancer Patient

Oral pain due to cancer and associated treatments is common. The prevalence and severity of oral cancer is high. Painful oral mucositis develops in head and neck cancer patients following surgery and associated radiation therapy and/or chemotherapy. In addition, oral pain, including pain from mucositis, occurs in patients receiving chemotherapy for cancers of the hematopoietic system and cancers at other anatomic sites. Despite pain management practices that include high-dose opioid analgesics, patients rarely obtain relief from either head and neck cancer pain or mucositis pain. Because oral pain in cancer patients is likely due to both nociceptive and neuropathic mechanisms, effective management of pain requires treatments for both processes. As knowledge of the pathophysiology of oral pain in cancer patients increases, new approaches for the prevention and management are anticipated. This article focuses on the emerging evidence that supports the molecular mechanisms and the unique oral micro-neuroanatomy that in combination produce the severe oral pain experienced by cancer patients. In addition, this article summarizes the current state of clinical management of oral mucositis pain.

Mucoadhesive Electrospun Patch Delivery of Lidocaine to the Oral Mucosa and Investigation of Spatial Distribution in a Tissue Using MALDI-Mass Spectrometry Imaging

Many oral mucosal conditions cause considerable and prolonged pain that to date has been difficult to alleviate via topical delivery, and the use of injection causes many patients dental anxiety and needle-prick pain. Therefore, developing a noninjectable drug delivery system as an alternative administration procedure may vastly improve the health and wellbeing of these patients. Recent advances in the development of mucoadhesive electrospun patches for the direct delivery of therapeutics to the oral mucosa offer a potential solution, but as yet, the release of local anesthetics from this system and their uptake by oral tissue have not been demonstrated. Here, we demonstrate the fabrication of lidocaine-loaded electrospun fiber patches, drug release, and subsequent uptake and permeation through the porcine buccal mucosa. Lidocaine HCl and lidocaine base were incorporated into the electrospun patches to evaluate the difference in drug permeation for the two drug compositions. Lidocaine released from the lidocaine HCl-containing electrospun patches was significantly quicker than from the lidocaine base patches, with double the amount of drug released from the lidocaine HCl patches in the first 15 min (0.16 ± 0.04 mg) compared to that from the lidocaine base patches (0.07 ± 0.01 mg). The permeation of lidocaine from the lidocaine HCl electrospun patches through ex vivo porcine buccal mucosa was also detected in 15 min, whereas permeation of lidocaine from the lidocaine base patch was not detected. Matrix-assisted laser desorption ionization-mass spectrometry imaging was used to investigate localization of lidocaine within the oral tissue. Lidocaine in the solution as well as from the mucoadhesive patch penetrated into the buccal mucosal tissue in a time-dependent manner and was detectable in the lamina propria after only 15 min. Moreover, the lidocaine released from lidocaine HCl electrospun patches retained biological activity, inhibiting veratridine-mediated opening of voltage-gated sodium channels in SH-SY5Y neuroblastoma cells. These data suggest that a mucoadhesive electrospun patch may be used as a vehicle for rapid uptake and sustained anesthetic drug delivery to treat or prevent oral pain.

Personalized anesthetic patches for dental applications

Topical anesthetics are widely used in dental procedures. However, most commercially available medications are in the form of liquid or semisolid, which cannot provide prolonged effect intraorally. To address this issue, we proposed the use of three-dimensional printing (3DP) to fabricate a customizable dental anesthetic patch loaded with lidocaine that can be fitted perfectly onto the affected tooth. It has been shown that that patch can adhere on the tooth for more than 1 h, while releasing lidocaine from the patch made of hydrogels. In addition, the results illustrated the possibility of controlling the drug release profile by altering the shape of the patch, as well the use of a 3DP tooth model as the drug testing platform. Taken together, these data further reinforce the vast potential of the application of 3DP technology in personalized medicine.

Potential Therapeutic Effects of Gut Hormones, Ghrelin and Obestatin in Oral Mucositis

Chemotherapy and/or head and neck radiotherapy are frequently associated with oral mucositis. Oral pain, odynophagia and dysphagia, opioid use, weight loss, dehydration, systemic infection, hospitalization and introduction of a feeding tube should be mentioned as the main determinated effect of oral mucositis. Oral mucositis leads to a decreased quality of life and an increase in treatment costs. Moreover, oral mucositis is a life-threatening disease. In addition to its own direct life-threatening consequences, it can also lead to a reduced survival due to the discontinuation or dose reduction of anti-neoplasm therapy. There are numerous strategies for the prevention or treatment of oral mucositis; however, their effectiveness is limited and does not correspond to expectations. This review is focused on the ghrelin and obestatin as potentially useful candidates for the prevention and treatment of chemo- or/and radiotherapy-induced oral mucositis.

Hybrid Hydrogel Composed of Polymeric Nanocapsules Co-Loading Lidocaine and Prilocaine for Topical Intraoral Anesthesia

This study reports the development of nanostructured hydrogels for the sustained release of the eutectic mixture of lidocaine and prilocaine (both at 2.5%) for intraoral topical use. The local anesthetics, free or encapsulated in poly(ε-caprolactone) nanocapsules, were incorporated into CARBOPOL hydrogel. The nanoparticle suspensions were characterized in vitro in terms of particle size, polydispersity, and surface charge, using dynamic light scattering measurements. The nanoparticle concentrations were determined by nanoparticle tracking analysis. Evaluation was made of physicochemical stability, structural features, encapsulation efficiency, and in vitro release kinetics. The CARBOPOL hydrogels were submitted to rheological, accelerated stability, and in vitro release tests, as well as determination of mechanical and mucoadhesive properties, in vitro cytotoxicity towards FGH and HaCaT cells, and in vitro permeation across buccal and palatal mucosa. Anesthetic efficacy was evaluated using Wistar rats. Nanocapsules were successfully developed that presented desirable physicochemical properties and a sustained release profile. The hydrogel formulations were stable for up to 6 months under critical conditions and exhibited non-Newtonian pseudoplastic flows, satisfactory mucoadhesive strength, non-cytotoxicity, and slow permeation across oral mucosa. In vivo assays revealed higher anesthetic efficacy in tail-flick tests, compared to a commercially available product. In conclusion, the proposed hydrogel has potential for provision of effective and longer-lasting superficial anesthesia at oral mucosa during medical and dental procedures. These results open perspectives for future clinical trials.