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Abstract Background The present systematic review intended to evaluate the current evidence on the modalities used for treating iatrogenic late paresthesia in the oral tissues innervated by the mandibular branch of the trigeminal nerve. Main text As a common side effect of dental procedures, paresthesia can exert a profound adverse effect on patients’ quality of life. The inferior alveolar nerve (IAN) and lingual nerve (LN) have the highest chance of injury during several dental procedures, including mandibular orthognathic surgeries, implant placement, extraction of the third molar, anesthetic injections, flap elevation, and endodontic treatments. Moreover, several methods have been proposed for treating iatrogenic late paresthesia, including photobiomodulation (PBM), microsurgery, medication, and close observation until achieving spontaneous recovery of sensation. However, no gold standard treatment for iatrogenic paresthesia has been agreed upon up to now. The present study included a comprehensive search of the databases of PubMed, Embase, Scopus, and Web of Science up to December 04, 2023, resulting in a total of 3122 related studies. Then, the titles, abstracts, and full texts of the studies were evaluated. Ultimately, seven controlled randomized trials (RCTs) were included in the final analysis. Also, the risk of bias was assessed using the Joanna Briggs Institute (JBI) critical appraisal checklist. Among all fields, randomization, allocation concealment, and data analysis were found to have the highest chance of bias in the included studies. Conclusions In conclusion, PBM, vitamin B12, and corticosteroids could accelerate the recovery of late paresthesia. However, considering the low sample size of the included studies and the high risk of methodological bias, it is recommended to perform further RCTs with robust study designs following Good Clinical Practice (GCP) guidelines to achieve more reliable results.

Background: The present systematic review intended to evaluate the current evidence on the modalities used for treating iatrogenic late paresthesia in the oral tissues innervated by the mandibular branch of the trigeminal nerve. Main text: As a common side effect of dental procedures, paresthesia can exert a profound adverse effect on patients' quality of life. The inferior alveolar nerve (IAN) and lingual nerve (LN) have the highest chance of injury during several dental procedures, including mandibular orthognathic surgeries, implant placement, extraction of the third molar, anesthetic injections, flap elevation, and endodontic treatments. Moreover, several methods have been proposed for treating iatrogenic late paresthesia, including photobiomodulation (PBM), microsurgery, medication, and close observation until achieving spontaneous recovery of sensation. However, no gold standard treatment for iatrogenic paresthesia has been agreed upon up to now. The present study included a comprehensive search of the databases of PubMed, Embase, Scopus, and Web of Science up to December 04, 2023, resulting in a total of 3122 related studies. Then, the titles, abstracts, and full texts of the studies were evaluated. Ultimately, seven controlled randomized trials (RCTs) were included in the final analysis. Also, the risk of bias was assessed using the Joanna Briggs Institute (JBI) critical appraisal checklist. Among all fields, randomization, allocation concealment, and data analysis were found to have the highest chance of bias in the included studies. Conclusions: In conclusion, PBM, vitamin B12, and corticosteroids could accelerate the recovery of late paresthesia. However, considering the low sample size of the included studies and the high risk of methodological bias, it is recommended to perform further RCTs with robust study designs following Good Clinical Practice (GCP) guidelines to achieve more reliable results. [ABSTRACT FROM AUTHOR]

Objectives: MR neurography has the ability to detect and depict peripheral nerve injuries. This study evaluated the potential of MR neurography in the diagnosis of post-traumatic trigeminal neuropathy. Methods: Forty-one participants prospectively underwent MR neurography of the lingual and inferior alveolar nerves using a 3D TSE STIR black-blood sequence. Two blinded and independent observers recorded the following information for each nerve of interest: presence of injury, nerve thickness, nerve signal intensity, MR neurography Sunderland class, and signal gap. Afterwards, the apparent nerve-muscle contrast-to-noise ratio and apparent signal-to-noise ratio were calculated. Clinical data (neurosensory testing score and clinical Sunderland class) was extracted retrospectively from the medical records of patients diagnosed with post-traumatic trigeminal neuropathy. Results: Compared to neurosensory testing, MR neurography had a sensitivity of 38.2% and specificity of 93.5% detecting nerve injuries. When differentiated according to clinical Sunderland class, sensitivity was 19.1% in the presence of a low class injury (I to III) and improved to 83.3% in the presence of a high class (IV to V). Specificity remained unchanged. The area under the curve using the apparent nerve-muscle contrast-to-noise ratio, apparent signal-to-noise ratio, and nerve thickness to predict the presence of an injury was 0.78 (p <.05). Signal intensities and nerve diameter increased in injured nerves (p <.05). Clinical and MR neurography Sunderland scores positively correlated (correlation coefficient = 0.53; p =.005). Conclusions: This study shows that MR neurography can accurately differentiate between injured and healthy nerves, especially in the presence of a more severe nerve injury. Clinical relevance statement: MR neurography is not only able to detect trigeminal nerve injuries, but it can also provide information about the anatomical specifications of the injury, which is not possible with clinical neurosensory testing. This makes MR neurography an added value in the management of post-traumatic trigeminal neuropathy. Key Points: • The current diagnosis of post-traumatic trigeminal neuropathy is mainly based on clinical examination. • MR neurography is able to visualize and stratify peripheral trigeminal nerve injuries. • MR neurography contributes to the diagnostic process as well as to further decision-making. [ABSTRACT FROM AUTHOR]

Background: Disruption of peripheral branches of the trigeminal nerve in the field of maxillofacial surgery is a known risk due to the close connection of these branches with the bony structures of the maxilla and mandible. As a result, injuries of the lingual nerve and inferior alveolar nerve take place within routine maxillofacial surgery procedures, including local anesthetic injection, wisdom tooth surgery, and dental implant placement, resulting in paresthesia and dysesthesia. During the last three decades, low-level lasers (LLL) have been frequently used in various medical fields. Lately, this application has increased in several sectors. Methods and materials: This experiment was designed to explore the effect of low-level laser therapy (LLLT) with Nd:YAG on the paresthesia and dysesthesia of the lower lip. This ethics committee of Tbzmed, Tabriz, Iran, proved the present experiment with ethical code: IR.TBZMED.REC.1401.839. Results: After completing 10 sessions of laser therapy for the case group consisting of 25 patients with lower lip anesthesia, the visual analog scale index results revealed that following six sessions of laser therapy, a significant difference appeared in contrast to the control group. Also, according to the two-point tests, significant difference among the experimental and the control group appeared after ninth session of the laser therapy. Conclusions: Altogether, these data suggested LLLT with Nd:YAG as an effective treatment option for decreasing the anesthesia of the lower lip. [ABSTRACT FROM AUTHOR]

The aim was to present expert-based guidelines on the management of trigeminal nerve injuries. A two-round multidisciplinary Delphi study was conducted amongst international trigeminal nerve injury experts with a set of statements and three summary flowcharts using a nine-point Likert scale (1 = strongly disagree; 9 = strongly agree). An item was deemed appropriate if the median panel score was within the range of 7–9, undecided if the score was 4–6, and inappropriate if the score was 1–3. Consensus was achieved if at least 75% of panelists scored within one range. Eighteen specialists from dental, medical, and surgical specialties participated in both rounds. Consensus was reached on most statements related to training/services (78%) and diagnosis (80%). Statements related to treatment were mainly undecided due to a lack of sufficient evidence for some of the proposed treatments. Nevertheless, the summary treatment flowchart reached consensus with a median score of eight. Recommendations on follow-up and opportunities for future research were discussed. None of the statements were deemed inappropriate. A set of recommendations and accepted flowcharts are presented; these will aid professionals involved in managing patients with trigeminal nerve injuries. [ABSTRACT FROM AUTHOR]

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Dental malpractice claims, which pertain to legal actions against dentists accused of clinical negligence that caused harm to patients, have increased in the past ten years in South Korea. The claims are caused by complications, particularly trigeminal nerve injuries, resulting from various dental procedures. Medicolegal issues related to trigeminal nerve injury have not been previously described in South Korea. Therefore, in this study, we aimed to identify the general, dental, and judicial characteristics of closed dental malpractice claims. This study was designed as a descriptive study. We collected the data of 51 closed claims related to trigeminal nerve injury resulting from dental procedures such as dental implant emplacement, tooth extraction, and local anesthesia. The claims were decided by courts in South Korea between 2016 and 2023. The general, dental, and judicial characteristics of the claims were analyzed retrospectively. The average claim resolution period was 4.2 (range: 1.47–8.39) years post-adverse events that occurred more frequently in dental clinics (68.6 %) than in dental (25.5 %) or general hospitals (5.9 %). Inferior alveolar (66.7 %) and lingual (17.6 %) nerves were injured following dental procedures. The duty to inform was breached in 68.6 % of claims. The dental procedure performed (P < 0.001) and the injured nerve (P < 0.001) were associated with the violation of the duty to care. To improve the quality of dental care services, the analysis of the adverse events using various resources including judgments should be strongly addressed. [ABSTRACT FROM AUTHOR]

Background: Trigeminal nerve injury following endodontic treatment, leading to unpleasant sensations or partial sensory loss in the face or oral mucosa, is uncommon but significant when it occurs., Objective: This study analysed the pharmacological management of trigeminal nerve injuries (TNI) in a university-based hospital., Methods: We conducted a retrospective analysis of 47 patients who visited the Department of Orofacial Pain and Oral Medicine at Yonsei University Dental Hospital, Seoul, Korea, after TNI following endodontic procedures in primary clinics. Both objective tests and subjective evaluations, assessed the extent and duration of sensory injury during the initial visit. The patient's initial symptoms, presumed cause of TNI, referral delay (time interval between TNI and the first visit to our clinic), and medications were analysed to determine whether these factors affected the outcomes., Results: Most patients with TNI experienced dysesthesia with hypoesthesia (70.2%). The mandibular molars were predominantly affected (72.3%), with the inferior alveolar nerve (IAN), lingual nerve (LN), both IAN and LN, and maxillary nerve compromised in 83.0, 12.8, 2.1, and 2.1% of cases, respectively. Causes of TNI included local anaesthesia (29.8%), overfilling/over-instrumentation (25.5%), endodontic surgery (17.0%), and unknown factors (27.7%). A shorter referral delay was associated with better outcomes, with an average delay of 8.6 weeks for symptom improvement compared with 44.1 weeks for no change. The medication regimens included steroids, NSAIDs, topical lidocaine, vitamin B complex, Adenosine Triphosphate (ATP), antiepileptics, antidepressants, and opioids administered alone or in combination, with a mean duration of 20.7 weeks. 53.2% of the patients reported improvement in their symptoms, 27.7% experienced no significant change, and 19.1% had unknown outcomes., Conclusions: Swift referral to an orofacial pain specialist is recommended for effective recovery in cases of TNI arising from endodontic treatment., (© 2024 The Author(s). Journal of Oral Rehabilitation published by John Wiley & Sons Ltd.)

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BackgroundInjury to the trigeminal nerve often results in the development of chronic pain states including tactile allodynia, or hypersensitivity to light touch, in orofacial area, but its underlying mechanisms are poorly understood. Peripheral nerve injury has been shown to cause up-regulation of thrombospondin-4 (TSP4) in dorsal spinal cord that correlates with neuropathic pain development. In this study, we examined whether injury-induced TSP4 is critical in mediating orofacial pain development in a rat model of chronic constriction injury to the infraorbital nerve.MethodsOrofacial sensitivity to mechanical stimulation was examined in a unilateral infraorbital nerve ligation rat model. The levels of TSP4 in trigeminal ganglia and associated spinal subnucleus caudalis and C1/C2 spinal cord (Vc/C2) from injured rats were examined at time points correlating with the initiation and peak orofacial hypersensitivity. TSP4 antisense and mismatch oligodeoxynucleotides were intrathecally injected into injured rats to see if antisense oligodeoxynucleotide treatment could reverse injury-induced TSP4 up-regulation and orofacial behavioural hypersensitivity.ResultsOur data indicated that trigeminal nerve injury induced TSP4 up-regulation in Vc/C2 at a time point correlated with orofacial tactile allodynia. In addition, intrathecal treatment with TSP4 antisense, but not mismatch, oligodeoxynucleotides blocked both injury-induced TSP4 up-regulation in Vc/C2 and behavioural hypersensitivity.ConclusionsOur data support that infraorbital nerve injury leads to TSP4 up-regulation in trigeminal spinal complex that contributes to orofacial neuropathic pain states. Blocking this pathway may provide an alternative approach in management of orofacial neuropathic pain states.

To investigate a potential mechanism underlying trigeminal nerve injury-induced orofacial hypersensitivity, we used a rat model of chronic constriction injury to the infraorbital nerve (CCI-ION) to study whether CCI-ION caused calcium channel α2δ1 (Cavα2δ1) protein dysregulation in trigeminal ganglia and associated spinal subnucleus caudalis and C1/C2 cervical dorsal spinal cord (Vc/C2). Furthermore, we studied whether this neuroplasticity contributed to spinal neuron sensitization and neuropathic pain states. CCI-ION caused orofacial hypersensitivity that correlated with Cavα2δ1 up-regulation in trigeminal ganglion neurons and Vc/C2. Blocking Cavα2δ1 with gabapentin, a ligand for the Cavα2δ1 proteins, or Cavα2δ1 antisense oligodeoxynucleotides led to a reversal of orofacial hypersensitivity, supporting an important role of Cavα2δ1 in orofacial pain processing. Importantly, increased Cavα2δ1 in Vc/C2 superficial dorsal horn was associated with increased excitatory synaptogenesis and increased frequency, but not the amplitude, of miniature excitatory postsynaptic currents in dorsal horn neurons that could be blocked by gabapentin. Thus, CCI-ION-induced Cavα2δ1 up-regulation may contribute to orofacial neuropathic pain states through abnormal excitatory synapse formation and enhanced presynaptic excitatory neurotransmitter release in Vc/C2.

Introduction: Paresthesia is a common cause of dental malpractice litigation. Symptoms range from minimal to severely affecting the quality of life. Effective treatments of post‐traumatic paresthesias are scarce. This case report documents the first reported use of laser biostimulation to reverse a long‐standing paresthesia of the infraorbital nerve, resulting from a root coverage procedure of the maxillary right canine. Case presentation: A coronally repositioned flap with enamel matrix derivative was used to treat gingival recession on the buccal surface of tooth #6 of a 35‐year‐old Caucasian female. One week later the patient reported lip numbness. The patient declined further treatment, and the paresthesia remained unchanged for the next 13 months. The patient then consented to laser biostimulation with a 1064 nm neodymium:yttrium aluminum garnet laser. A single laser biostimulation treatment resulted in an immediate and dramatic improvement of lip sensation. The patient's symptoms improved over the next 2½ years without further treatment. Conclusion: The cause of the paresthesia and the exact mechanism of its reversal remain unknown, although speculated causes and the possible mechanisms of action of low‐level laser therapy are discussed. Laser biostimulation for treatment of peripheral nerve injury is noninvasive and may eliminate the need for corticosteroids or other more invasive treatment modalities. It may not be effective in all paresthesia cases, but when used properly, laser therapy offers a safe treatment alternative for an often troubling problem. [ABSTRACT FROM AUTHOR]

The regeneration of nerve injuries after oral surgery procedures is a quite often attempted procedure in dental medicine. Despite several proposed technical approaches, there is still a lack of consensus on which should be considered the gold standard procedure, even-though in the last decades, the use of collagen-based devices allowing a tension-free direct neurorrhaphy has been used. A systematic search of multiple electronic databases and hand searching was conducted to assess the level of evidence behind the use of type I collagen devices to treat nerve injuries after oral surgery procedures. After screening, four articles (one case series and three retrospective studies) including overall 65 patients suffering from inferior alveolar (IAN)/lingual nerve (LN) injury after mandibular wisdom tooth extraction, met the inclusion criteria and could be included. The Oxford Centre for evidence-based medicine (OCEBM) scaling system was used to evaluate the quality of the included studies. Positive clinical results in terms of sensorial improvements were recorded at least 3 months after surgery, even-though the overall level of evidence is low. The use of collagen membranes to enhance nerve regeneration in oral surgery results in promising results. Nevertheless, additional clinical comparative trials with larger sample sizes are needed. [ABSTRACT FROM AUTHOR]

Aims: To evaluate the diagnostic value of non--nerve-selective MRI sequences in posttraumatic trigeminal neuropathic pain (PTNP). Methods: This study retrospectively analyzed all MRI protocols performed between February 2, 2012 and June 20, 2018 commissioned by the Department of Oral and Maxillofacial Surgery, University Hospitals Leuven. Demographic, clinical, and radiologic data were extracted from the records of patients with an MRI in the context of PTNP. A contingency table was constructed based on the opinions of the treating physician and the radiologist who initially evaluated the MRI. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. Results: The sample consisted of 27 women (65.9%) and 14 men (34.1%). The sensitivity and negative predictive value of MRI in PTNP were 0.18 and 0.77, respectively. Artifacts interfered with visualization of a possible cause of the trigeminal pain in 24.4% of MRIs. Almost all artifacts (90%) were caused by metal debris originating from the causal procedure or posttraumatic surgeries. MRI resulted in changed management for PTNP patients only once. Conclusion: The diagnostic value of non--nerve-selective MRI sequences for PTNP is low and has little impact on clinical management. Therefore, there is a need for dedicated sequences with high resolution and low artifact susceptibility for visualizing the posttraumatic injuries of the trigeminal branches. [ABSTRACT FROM AUTHOR]

The infraorbital nerve is a branch of the trigeminal nerve. Injury to the infraorbital nerve can be caused by trauma, including various facial fractures. Due to this nerve injury, patients complain of numbness and pain in the entire cheek, the ala of nose, and upper lip. In general, spontaneous sensory recovery is expected after decompressive surgery. If nerve transection is confirmed, however, neurorrhaphy is typically performed. Here, we present a case in which microsurgery was not performed in a patient with Sunderland grade V avulsion injury of the infraorbital nerve due to a facial bone fracture. Gradual nerve function recovery was confirmed to be possible with conservative treatment and rehabilitation alone. These findings suggest that the nerve function recovery can be expected with conservative treatment, even for severe nerve injury for which microsurgery cannot be considered. [ABSTRACT FROM AUTHOR]

The structural plasticity of neurites in the central nervous system (CNS) diminishes dramatically after initial development, but the peripheral nervous system (PNS) retains substantial plasticity into adulthood. Nevertheless, functional reinnervation by injured peripheral sensory neurons is often incomplete [1-6]. To investigate the developmental control of skin reinnervation, we imaged the regeneration of trigeminal sensory axon terminals in live zebrafish larvae following laser axotomy. When axons were injured during early stages of outgrowth, regenerating and uninjured axons grew into denervated skin and competed with one another for territory. At later stages, after the establishment of peripheral arbor territories, the ability of uninjured neighbors to sprout diminished severely, and although injured axons reinitiated growth, they were repelled by denervated skin. Regenerating axons were repelled specifically by their former territories, suggesting that local inhibitory factors persist in these regions. Antagonizing the function of several members of the Nogo receptor (NgR)/RhoA pathway improved the capacity of injured axons to grow into denervated skin. Thus, as in the CNS, impediments to reinnervation in the PNS arise after initial establishment of axon arbor structure.

Objective: To provide a preliminary comparison of traditional clinical neurosensory examination (CNE) and current perception threshold (CPT). Method and Materials: This is a retrospective chart audit of patients with trigeminal nerve injuries related to dental treatment who were evaluated with both CNE and CPT assessments (electrical stimulus tests) after presenting with altered sensation involving either the inferior alveolar nerve (IAN) or lingual nerve (LN) distributions. The tests were performed on the anterior two-thirds of the tongue for LN injuries and the lower lip and chin for IAN injuries. Results were defined as hyper-, hypo-, or normal sensory response. Results: Twelve charts were reviewed; 10 of the 12 nerve injuries occurred secondary to mandibular third molar extraction affecting 7 LN and 5 IAN branches. Following LN injuries, the C, and A-delta fibers assessment demonstrated hyposensitivity in the affected nerve territory in CPT and the CNE tests with the exception of 1 normal nerve response in 5-Hz CPT. Within the LN injury group, good correlation was observed between the CNE and CPT tests with the exception of brush stroke and 250-Hz CPT stimuli. Following IAN injuries, sensory testing results were more varied. A-beta fiber evaluation demonstrated hyposensitivity to VF in all patients and in 4 of 5 for brush test. One patient was hypersensitive for the brush test. The response to 2,000-Hz electrical stimulus demonstrated hyposensitivity in 3 patients, hypersensitivity in 1 (the same patient that was hypersensitive for brush), and normal sensitivity in 1 patient. Good correlations were found only between the CPT 5-Hz and heat and cold tests. Only 1 patient (IAN injury) reported pain that was hypersensitive for heat, cold, pinprick, brush, and 250-Hz and 2,000-Hz stimuli. Conclusion: Following LN injuries, CNE and CPT tests provided similar findings. More disparity was observed between the CNE and CPT methods in the IAN injury evaluation. For LN injury assessments, CNE alone appears to be adequate for assessing nerve injuries. [ABSTRACT FROM AUTHOR]

The regeneration of nerve injuries after oral surgery procedures is a quite often attempted procedure in dental medicine. Despite several proposed technical approaches, there is still a lack of consensus on which should be considered the gold standard procedure, even-though in the last decades, the use of collagen-based devices allowing a tension-free direct neurorrhaphy has been used. A systematic search of multiple electronic databases and hand searching was conducted to assess the level of evidence behind the use of type I collagen devices to treat nerve injuries after oral surgery procedures. After screening, four articles (one case series and three retrospective studies) including overall 65 patients suffering from inferior alveolar (IAN)/lingual nerve (LN) injury after mandibular wisdom tooth extraction, met the inclusion criteria and could be included. The Oxford Centre for evidence-based medicine (OCEBM) scaling system was used to evaluate the quality of the included studies. Positive clinical results in terms of sensorial improvements were recorded at least 3 months after surgery, even-though the overall level of evidence is low. The use of collagen membranes to enhance nerve regeneration in oral surgery results in promising results. Nevertheless, additional clinical comparative trials with larger sample sizes are needed.

Background: Neurosensory changes are frequently observed in the patients with mid-face fractures, and these symptoms are often caused by infraorbital nerve (ION) damage. Although ION damage is a relatively common phenomenon, there are no established and objective methods to evaluate it. The aim of this study was to test whether trigeminal somatosensory evoked potential (TSEP) could be used as a prognostic predictor of ION damage and TSEP testing was an objective method to evaluate ION injury. Methods: In this prospective TSEP study, 48 patients with unilateral mid-face fracture (only unilateral blow out fracture and unilateral zygomaticomaxillary fracture were included) and potential ION damages were enrolled. Both sides of the face were examined with TSEP and the non-traumatized side of the face was used as control. We calculated the latency difference between the affected and the unaffected sides. Results: Twenty-four patients recovered within 3 months, and 21 patients took more than 3 months to recover. The average latency difference between the affected side and unaffected side was 1.4 and 4.1 ms for the group that recovered within 3 months and the group that recovered after 3 months, respectively. Conclusion: Patients who suffered ION damage showed prolonged latency when examined using the TSEP test. TSEP is an effective tool for evaluation of nerve injury and predicting the recovery of patients with ION damage. [ABSTRACT FROM AUTHOR]

Aims: To compare the impacts of trigeminal neuralgia (TN) and painful posttraumatic trigeminal neuropathy (PPTTN) on psychologic function and health-related quality of life (HRQoL) using a comprehensive quantitative assessment. Methods: This was a comparative cross-sectional study. A total of 97 patients diagnosed with PPTTN and 40 patients diagnosed with TN who sought treatment at an orofacial pain clinic completed standardized self-report measures of pain intensity, neuropathic symptoms, pain self-efficacy, mood, and indicators of general and oral HRQoL. Differences between the PPTTN and TN groups were tested, and associations of each condition with pain severity, psychologic function, and HRQoL were examined. Results: The majority of PPTTN (66%) and TN patients (80%) were affected by orofacial pain. Pain attacks were more frequent in TN (71%) than PPTTN (28%) patients, while numbness was more common in PPTTN (51%) than TN (12%) patients. Pain intensity was higher in TN for intermittent and affective pain dimensions. Both PPTTN and TN had a significant, but comparable, impact on patients' oral HRQoL. The burden of condition on overall health was significantly more pronounced in patients with TN than PPTTN, with evident differences in the mobility and self-care domains. There was a trend showing that more TN (54%) than PPTTN (36%) patients reported signs of depression, but clinically significant anxiety was comparably high in both groups (34% to 39%). Anxiety and pain self-efficacy were closely related to oral and general health statuses in both groups. Conclusions: Both TN and PPTTN are associated with significant psychosocial burden and reduced HRQoL, indicating a need to develop effective treatments for neuropathic orofacial pain that target functional restoration. [ABSTRACT FROM AUTHOR]

During oral and head and neck surgery, oral vestibular incisions may require a transverse incision on the upper lip mucosa, resulting in possible sensory disturbances in the area innervated by infraorbital nerve (ION) branches. Although sensory disturbances are attributed to nerve injuries, anatomy textbooks have not showed the precise distribution patterns of the ION branches in the upper lip. Furthermore, no detailed study has been available on this issue. This study aimed to reveal the precise distribution patterns of ION branches in the upper lip by dissecting the detached upper lip and cheek area using a stereomicroscope. During a gross anatomy course at Niigata University (2021–2022), nine human cadavers were examined with special focus on the relationship between ION branches in the upper lip and the layered structure of facial muscles. The ION branched to the inferior palpebral (IP), external and internal nasal, and superior labial (lateral and medial) nerves. The ION branches in the upper lip did not run in a horizontal pattern from outside to inside but showed a predominantly vertical pattern. Considering their course, incising the upper lip mucosa transversely may cause paresthesia of the ION branches. The internal nasal (IN) and medial superior labial (SLm) branches tended to penetrate the orbicularis oris and descend between this muscle and labial glands, whereas the lateral superior labial (SLl) branches tended to innervate the skin. These findings suggest that a lateral mucosal incision is recommended for oral vestibular incisions of the upper lip and that deeper incisions to the labial glands should be avoided when incising the medial side to preserve the ION during surgery from an anatomical point of view. [Display omitted] • Infraorbital nerve branches in the upper lip run a vertical pattern. • Some branches descend between the orbicularis oris and labial glands. • Infraorbital nerve branches may be injured during oral vestibular incisions. • A lateral incision on the upper lip mucosa reduces the risk of thick nerve injury. • Deeper incisions to the labial glands should be avoided. [ABSTRACT FROM AUTHOR]

Objectives: The study represents a preliminary evaluation of the accuracy of the dynamic navigation system (DNS) in coronectomy of the mandibular third molar (M3M)., Methods: The study included participants with an impacted M3M near the inferior alveolar canal. The coronectomy planes were designed before the surgery using cone-beam computed tomography (CBCT) imaging data and then loaded into the DNS program. Intraoperatively, the navigation system was used to guide the complete removal of the target crown. Postoperative CBCT imaging was used to assess any three-dimensional deviations of the actual postoperative from the planned preoperative section planes for each patient., Results: A total of 12 patients (13 teeth) were included. The root mean square (RMS) deviation of the preoperatively designed plane from the actual postoperative surface was 0.69 ± 0.21 mm, with a maximum of 1.45 ± 0.83/-1.87 ± 0.63 mm deviation. The areas with distance deviations < 1 mm, 1-2 mm, and 2-3 mm were 71.97 ± 5.72 %, 22.96 ± 6.57 %, and 4.52 ± 2.28 %, respectively. Most patients showed extremely high convexity of the surface area located in the mesial region adjacent to the base of the extraction socket. There was no observable evidence of scratching of the buccolingual bone plate at the base of the extraction socket by the handpiece drill., Conclusions: These results provide preliminary support for the use of DNS-based techniques when extracting M3M using a buccal approach. This would improve the accuracy of coronectomy and reduce the potiential damage to the surrounding tissue., Clinical Significance: DNS is effective for guiding coronectomy., Competing Interests: Declaration of Competing Interest The authors declare there is no conflict of interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Objectives: The aim of this in vitro study was to evaluate the effect of a 3D-printed drill sleeve (DS) on the precision and duration of coronectomy sections., Materials and Methods: Thirty-six trainees and oral surgeons performed 72 coronectomy cuts in a 3D-printed, entirely symmetric mandible model. Coronectomy was performed freehand (FH) on one side and with a DS on the other side. The occurrence of "too superficial" (≥ 4 mm unprepared lingual tooth tissue) and "too deep" (drilling ≥ 1 mm deeper as tooth contour) cuts and sectioning times were registered., Results: In 7 cases, the sections were "too deep" with FH, while none with DS (OR: 18.56; 95%CI: 1.02-338.5; p = 0.048). The deviation between virtually planned and real cut depths was significantly greater in the FH group (1.91 ± 1.62 mm) than in DS group (1.21 ± 0.72 mm) (p < 0.001). A total of 18 "too superficial" buccolingual sections occurred with FH, while 8 cases with DS (OR: 3.50; 95%CI: 1.26-9.72; p = 0.016). Suboptimal sections did not correlate with experience (p = 0.983; p = 0.697). Shortest, suboptimal drillings were most frequently seen distolingually (OR: 6.76; 95% CI: 1.57-29.07; p = 0.01). In the inexperienced group, sectioning time was significantly longer with FH (158.95 ± 125.61 s vs. 106.92 ± 100.79 s; p = 0.038)., Conclusions: The DS effectively reduced tooth sectioning times by less experienced colleagues. Independently from the level of experience, the use of DS obviated the need for any preparation outside the lingual tooth contour and significantly decreased the occurrence of "too superficial" cuts, leaving thinner unprepared residual tooth tissue lingually., Clinical Relevance: Coronectomy sections may result in lingual hard and soft tissue injury with the possibility of damaging the lingual nerve. The precision of the buccolingual depth-control can be improved, while surgical time can be reduced when applying a drilling sleeve., (© 2023. The Author(s).)

The aim of this study is to assess the relationship between somatosensory functional changes and inferior alveolar nerve (IAN) exposure after impacted mandibular third molars (M3M) removal. We recruited 35 patients who underwent impacted M3M extraction near the IAN. The M3Ms were extracted by combined endoscopy, piezosurgery, and contra-angle high-speed turbine handpiece. All IAN canal perforations and exposed regions were recorded and measured by endoscopy after extraction and on cone-beam computed tomography (CBCT) images before extraction. The patients were followed up 1, 7, and 35 days after surgery. A standardized quantitative sensory testing (QST) battery was performed on the lower lip skin. All of 35 cases had exposed IAN on CBCT images, 5 of which had no exposed IAN under endoscopy. For the other 30 cases, the endoscopy-measured IAN length and width were shorter than the CBCT measurements (P < 0.001). The warm and mechanical detection thresholds (MDT) on the operation side were significantly higher than the contralateral side after surgery (P < 0.05). Thermal sensory limen, MDT, and cold pain threshold were strongly correlated with the exposed IAN length and MDT also with the exposed IAN width one day after surgery. In conclusion, it was found that not all exposed IAN in CBCT images were real exposure after surgery. The intraoperative exposed IAN endoscopic measurements were smaller than by CBCT and strongly correlated with some QST parameters., (© 2023. The Author(s).)