Narrative review: the evidence for neurotoxicity of dental local anesthetics

Surgical outcomes of the surgical techniques following management of iatrogenic trigeminal nerve injuries: A systematic review

Objective

To investigate the effectiveness of the microsurgical treatment in restoring full sensory recovery following trigeminal nerve injuries caused by iatrogenic oral and maxillofacial surgical interventions.

Methods

A detailed search was conducted on the Cochrane central register of controlled trials, Medline and Embase. Clinical studies with at least twelve months of follow up were included and assessment of risks of bias was made using the Robbin I assessment tool.

Results

Six studies were identified in the searches which include 227 patients. The lingual nerve was the most common injured nerve, followed by the inferior alveolar nerve. Third molar removal was the most frequent cause of nerve injury, followed by root canal treatment, pathology excision, coronectomy, orthognathic surgery, dental implants and then local anaesthetic injections. Overall, surgical interventions for nerve injuries showed neurosensory improvement postoperatively in the majority of patients.

Conclusion

Direct neurorrhaphy is still the gold-standard technique when the tension at the surgical site is minimal. Promising results have been noted on conduit applications following traditional repair or grafting. Further research is needed on the efficacy of allografting and conduit applications in nerve repair.

Notoginsenoside R1 attenuates bupivacaine induced neurotoxicity by activating Jak1/Stat3/Mcl1 pathway

Bupivacaine, a common amide local anesthetic, can provide effective analgesia or pain relief but can also cause neurotoxicity, which remains a mounting concern in clinic and animal care. However, the precise underlying mechanisms have not been fully elucidated. A natural compound, notoginsenoside R1 (NG-R1) has been reported to exhibit a neuroprotective role in stress conditions. In this study, we explored the function and mechanism of NG-R1 in alleviating bupivacaine-induced neurotoxicity in mouse hippocampal neuronal (HT-22) and mouse neuroblastoma (Neuro-2a) cell lines. Our results exhibited that NG-R1 treatment can significantly rescue the decline of cell survival induced by bupivacaine. Tunel staining and western blotting showed that NG-R1 could attenuate BPV‑induced cell apoptosis. Besides, we focused on Mcl1 as a potential target as it showed opposite expression tendency in response to NG-R1 and bupivacaine exposure. Mcl1 knockdown blocked the inhibitory effect of NG-R1 on cell apoptosis against bupivacaine treatment. Intriguingly, we found that NG-R1 can upregulate Mcl1 transcription by activating Stat3 and promote its nuclear translocation. In addition, NG-R1 can also promote Jak1 phosphorylation and docking analysis provide a predicted model for interaction between NG-R1 and phosphorylated Jak1. Taken together, our results demonstrated that NG-R1 can attenuate bupivacaine induced neurotoxicity by activating Jak1/Stat3/Mcl1 pathway.

Mental and Lingual Nerve Paresthesia Following Infiltration Anesthesia for Dental Implant Placement in a Patient With Guillain-Barré Syndrome

Guillain-Barré syndrome (GBS) is a rare rapid onset autoimmune peripheral polyneuropathy, most commonly characterized by inflammatory demyelination of peripheral nerves. Patients with GBS are considered higher risk for anesthetic-induced neurotoxicity caused by demyelination. In the present report, a case is described of a 56-year-old man with GBS who experienced mental and lingual nerve paresthesia following infiltration anesthesia for dental implant placement in the posterior mandible. The pareshesia lasted 5 months postoperatively and subsided spontaneously without any intervention. The patient was successfully restored with fixed partial dental prosthesis without any other complication. This is considered the first report of such complication in patient with GBS after local anesthesia in the oral and maxillofacial region. Possible pathogenic mechanism of the complication and clinical implications are discussed.

Paresthesia in dentistry: The ignored neurotoxicity of local anesthetics

Local anesthetics are frequently used by dentists to relieve localized discomfort of the patient and improve treatment conditions. The risk of paresthesia after local anesthesia is frequently encountered in dental clinics. The neurotoxicity of local anesthetics is a disregarded factor in paresthesia. The review summarizes the types of common local anesthetics, incidence and influencing factors of paresthesia after local anesthesia, and systematically describes the neurotoxicity mechanisms of dental local anesthetic. Innovative strategies may be developed to lessen the neurotoxicity and prevent paresthesia following local anesthesia with the support of a substantial understanding of paresthesia and neurotoxicity.

Anesthetic efficacy of buffered 4% articaine for mandibular first molar infiltration: a crossover clinical trial

Background

The limited studies on the effect of buffering on the clinical efficacy of articaine have reported controversial results. The purpose of this study was to clinically compare the pain of injection, anesthetic success, onset, and duration of pulpal anesthesia of buffered 4% articaine with epinephrine 1:100000 versus a non-buffered 4% articaine with epinephrine 1:100000 formulation for buccal infiltration of the mandibular first molar.

Methods

Sixty-three volunteers were enrolled in the study. All volunteers received two injections consisting of a single mandibular first molar buccal infiltration with 1.8 ml of 4% articaine with epinephrine 1:100000 and 1.8 ml of 4% articaine with epinephrine 1:100000 buffered with 8.4% sodium bicarbonate. The infiltrations were applied in two separate appointments spaced at least one week apart. After injection of the anesthetic solution at the examined site, the first molar was pulp-tested every 2 min for the next 60 min.

Results

Successful pulpal anesthesia was recorded in 69.8% of cases using non-buffered articaine solution and 76.2% of cases using buffered articaine solution, with no significant difference between the formulations (P = 0.219). The mean time of anesthesia onset for the volunteers with successful anesthetic outcome in both formulations (n = 43) was 6.6 ± 1.6 min for the non-buffered articaine solution and 4.5 ± 1.6 min for the buffered solution, which differed significantly (P = 0.001). In the same volunteers, the mean duration of pulpal anesthesia was 28.4 ± 7.1 min for non-buffered articaine solution and 30.2 ± 8.5 min for buffered articaine solution, with no significant difference between the formulations (P = 0.231). Considering the pain of injection, regardless of the anesthetic success, the mean values of VAS were 11.3 ± 8.2 mm for the non-buffered articaine solution and 7.8 ±6.5 mm for the buffered articaine solution, which differed significantly (P = 0.001 < 0.05).

Conclusion

According to the present study, 4% articaine with epinephrine can benefit from buffering and provide better anesthetic behavior, with improved onset and less pain during injection.

A Novel Scale to Assess Parental Satisfaction of Dental Local Anesthetic Techniques in Children: A Cross-Sectional Study

Background

Pain control is one of the most important aspects that can affect parental satisfaction of the dental care provided for children. Dental local anesthesia has the highest impact on pain sensation of the children. However, there is no scale in the literature to assess parental satisfaction of dental local anesthetic techniques.

Objectives

This study was aimed to assess the parental satisfaction with dental local anesthetic techniques for their children through designing a scale that reflects satisfaction and to study the validity and reliability of this scale.

Methods

A cross-sectional observational study was conducted on 150 parents (102 mothers and 48 fathers). Two techniques of local anesthesia were used for each child participated in this study (inferior alveolar nerve block and computerized intraosseous anesthesia). The developed scale consisted of 20 items in a 5-point Likert scale. Half of the items were written in a negative format. Internal consistency, validity, and factor analysis were performed in this study. Independent t-test was used to compare between the two techniques of anesthesia, between boys and girls and among fathers and mothers.

Results

Parental satisfaction mean values were higher in the computerized intraosseous anesthesia group in comparison to inferior alveolar nerve block (P value <0.05). The T-test showed that there was no difference between boys and girls regarding parental satisfaction (P value >0.05). Furthermore, fathers show lower satisfaction in the computerized interosseous anesthesia group (P value <0.05). Excellent internal consistency of this scale was resulted as Cronbach's alpha reliability coefficient was 0.985. After factor analysis, seven factor components were retained by using varimax rotation.

Conclusions

Findings of this study reported that the designed parental satisfaction of dental local anesthetic techniques scale (PSLAS) is a valid and reliable scale to be used. Moreover, this study showed that parental satisfaction was higher when computerized intraosseous anesthesia was used in comparison to inferior alveolar nerve block.

Articaine use does not routinely eliminate the need for palatal injections for primary maxillary molar extractions: a randomized cross-over clinical trial

Purpose

The aim of this study was to compare single buccal infiltration of 4% articaine versus routine buccal and palatal injections of 2% lidocaine during bilateral extraction of maxillary primary molars.

Methods

Thirty healthy children aged 6–9 years old requiring bilateral extraction of maxillary primary molars were enrolled into the trial. Randomization was performed in two steps. Routine buccal and palatal infiltrations were administered using 2% lidocaine in the control side. Four percent articaine was used for single buccal infiltration in the intervention side. WBFP scale (Wong-Baker FACES Pain scale) was employed for subjective assessment of pain. For objective evaluation of pain, FLACC scale (Face, Legs, Activity, Cry, Consolability) and physiological parameters of blood pressure and pulse rate were recorded.

Results

Analyses did not show any significant differences in blood pressure, pulse rate, and FLACC scale between groups (P value > 0.05). However, statistically lower WBFP scores were observed in articaine group as compared to lidocaine group (P value < 0.05); the difference was less than one unit which is not clinically considerable.

Conclusion

Single buccal infiltration of 4% articaine can be administered as an alternative for conventional infiltration of 2% lidocaine to avoid fear or uncooperative behavior of the child patient. However, the assessment of palatal tissue anesthesia is quite necessary before the procedure is initiated. In case of failure in achieving palatal anesthesia, a palatal injection should be given.

Ropivacaine Induces Cell Cycle Arrest in the G0/G1 Phase and Apoptosis of PC12 Cells via Inhibiting Mitochondrial STAT3 Translocation

STAT3 has neuroprotective effect via non-canonical activation and mitochondrial translocation, but its effect on ropivacaine-induced neurotoxicity remains unclear. Our previous study revealed that apoptosis was an important mechanism of ropivacaine-induced neurotoxicity; this study is to illustrate the relationship between STAT3 with ropivacaine-induced apoptosis. Those results showed that ropivacaine treatment decreased cell viability, induced cell cycle arrest in the G0/G1 phase, apoptosis, oxidative stress, and mitochondrial dysfunction in PC12 cells. Moreover, ropivacaine decreased the phosphorylated levels of STAT3 at Ser727 and downregulated the expression of STAT3 upstream gene IL-6. The mitochondrial translocation of STAT3 was also hindered by ropivacaine. To further illustrate the connection of STAT3 protein structure with ropivacaine, the autodock-vina was used to examine the interaction between STAT3 and ropivacaine, and the results showed that ropivacaine could bind to STAT3's proline site and other sites. In addition, the activator and inhibitor of mitoSTAT3 translocation were used to demonstrate it was involved in ropivacaine-induced apoptosis; the results showed that enhancing the mitochondrial STAT3 translocation could prevent ropivacaine-induced apoptosis. Finally, the expression of p-STAT3 and the levels of apoptosis in the spinal cord were also detected; the results were consistent with the cell experiment; ropivacaine decreased the expression of p-STAT3 protein and increased the levels of apoptosis in the spinal cord. We demonstrated that ropivacaine induced apoptosis by inhibiting the phosphorylation of STAT3 at Ser727 and the mitochondrial STAT3 translocation. This effect was reversed by the activation of the mitochondrial STAT3 translocation.