Clinical characteristics of trigeminal nerve injury referrals to a university centre

Cranial Nerve Injuries in Orthognathic Surgery: A Review of Literature

ABSTRACT

Orthognathic surgery is increasingly utilized to correct facial deformities and dental malocclusions, as well as to enhance facial aesthetics. Significant advancements in surgical planning and execution have made it more widespread and accessible. However, unfavorable outcomes or complications can occur, leading to potentially severe and possibly long-term consequences, such as cranial nerve injuries. This literature review investigates the cranial nerve complications associated with orthognathic surgery. We conducted an extensive search across available databases, analyzing relevant studies published up to September 30, 2023. Two authors independently selected articles for full-text review based on their titles and abstracts. The eligible studies reported cranial nerve injuries in individuals who had undergone orthognathic surgery. Our findings highlight the risk of cranial nerve injuries, their possible mechanism, management, and outcomes. It is imperative for surgeons to remain vigilant and informed and to communicate such information during preoperative patient consultation.

Towards clinically applicable automated mandibular canal segmentation on CBCT

OBJECTIVES

To develop a deep learning-based system for precise, robust, and fully automated segmentation of the mandibular canal on cone beam computed tomography (CBCT) images.

METHODS

The system was developed on 536 CBCT scans (training set: 376, validation set: 80, testing set: 80) from one center and validated on an external dataset of 89 CBCT scans from 3 centers. Each scan was annotated using a multi-stage annotation method and refined by oral and maxillofacial radiologists. We proposed a three-step strategy for the mandibular canal segmentation: extraction of the region of interest based on 2D U-Net, global segmentation of the mandibular canal, and segmentation refinement based on 3D U-Net.

RESULTS

The system consistently achieved accurate mandibular canal segmentation in the internal set (Dice similarity coefficient [DSC], 0.952; intersection over union [IoU], 0.912; average symmetric surface distance [ASSD], 0.046 mm; 95% Hausdorff distance [HD95], 0.325 mm) and the external set (DSC, 0.960; IoU, 0.924; ASSD, 0.040 mm; HD95, 0.288 mm).

CONCLUSIONS

These results demonstrated the potential clinical application of this AI system in facilitating clinical workflows related to mandibular canal localization.

CLINICAL SIGNIFICANCE

Accurate delineation of the mandibular canal on CBCT images is critical for implant placement, mandibular third molar extraction, and orthognathic surgery. This AI system enables accurate segmentation across different models, which could contribute to more efficient and precise dental automation systems.

Inferior Alveolar Nerve Canal Segmentation on CBCT Using U-Net with Frequency Attentions

Accurate inferior alveolar nerve (IAN) canal segmentation has been considered a crucial task in dentistry. Failing to accurately identify the position of the IAN canal may lead to nerve injury during dental procedures. While IAN canals can be detected from dental cone beam computed tomography, they are usually difficult for dentists to precisely identify as the canals are thin, small, and span across many slices. This paper focuses on improving accuracy in segmenting the IAN canals. By integrating our proposed frequency-domain attention mechanism in UNet, the proposed frequency attention UNet (FAUNet) is able to achieve 75.55% and 81.35% in the Dice and surface Dice coefficients, respectively, which are much higher than other competitive methods, by adding only 224 parameters to the classical UNet. Compared to the classical UNet, our proposed FAUNet achieves a 2.39% and 2.82% gain in the Dice coefficient and the surface Dice coefficient, respectively. The potential advantage of developing attention in the frequency domain is also discussed, which revealed that the frequency-domain attention mechanisms can achieve better performance than their spatial-domain counterparts.

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.

Dexamethasone and concentrated growth factors on peripheral nerve injury: A clinic-relevant animal study

BACKGROUND

Mandibular nerve injury is a common clinical condition that affects clinicians' management and patients' quality of life. In the literature, there are various effective treatments available. The primary purpose of this study was to determine and compare the effects of dexamethasone and concentrated growth factor (CGF) on regeneration in patients with nerve trauma that mimics clinical situations.

METHODS

In this study, 36 rats were divided into 3 groups: the control, dexamethasone and CGF groups. The inferior alveolar nerve was traumatized through the extraction socket after mandibular molar tooth extraction in each group.

RESULTS

The data showed a decrease in the control (4.5-4), dexamethasone (3-2), and CGF (4-3) groups according to the histological injury severity score (HISS) results. Compared with those in the other groups, the number of degenerative axons and edematous areas observed via histological examination were significantly lower in the CGF groups. Similarly, compared with those in the control group, the nNOS and Neurofilament-H positivity in the dexamethasone group on the 30th day (2,2 to 1,1 respectively) was significantly lower. The positivity of all the primary antibodies in the 3rd and 30th day CGF groups was significant compared than that in the dexamethasone 30th day group.

CONCLUSION

According to the results of the analysis of the immunohistopathological and HISS data, the CGF groups exhibited greater regeneration than did the dexamethasone groups.

Three-dimensional analysis of mandibular and mental canals corroborating with teeth and mental foramen by cone beam computed tomography

BACKGROUND

This study aimed to analyse the 3D patterns of the mandibular and mental canals (MDC and MC) referring to the surrounding prominent surgical landmarks such as teeth and mental foramen by cone beam computed tomography (CBCT).

METHODS

CBCT scans of 354 patients aged 18-67 years with mandibular first premolar to second molar were included and reconstructed 3-dimensionally (3D) by mimics. The parameters of MDC and MC were measured referring to teeth and mental foramen.

RESULTS

From the first premolars to the second molars, the mandibular canals showed a trend of gradually closer to the cementoenamel junction (CEJ) of the adjacent teeth and farther away from the buccal cortical plate. The distance of the MDC with the root apexes (RA) was relatively constant from the first premolar to the first molar, but became much closer to the second molar. About 10.8% of the second molars had MDC-RA distances of shorter than 2 mm, and 1.34% even had the MDC superior to the RA. Moreover, the Type III of MC presented in 66.0% of the subjects and had a relatively longer length. Besides, the existence of Type I MC may be related to the MDC featuring with close distances to the RA and CEJ of the adjacent teeth.

CONCLUSION

Dentists and surgeons should know the patterns of mandibular and mental canals. A better understanding of the MDC and MC and their relationship to local anatomical landmarks may facilitate the planning of surgeries and alert potential nerve injuries in the operative procedures.

Photobiomodulation Activates Microglia/Astrocytes and Relieves Neuropathic Pain in Inferior Alveolar Nerve Injury

Objective: This study aimed to determine microglial/astrocyte changes and their associated analgesic effect in inferior alveolar nerve injury (IANI) model rats treated with photobiomodulation therapy (PBMT) using a 940-nm diode laser. Background: Very few basic studies have investigated microglial/astrocyte dynamics following PBMT aimed at relieving neuropathic pain caused by IANI. Methods: Rats were divided into an IANI-PBM group, IANI+PBM group, and sham+PBM group. Observations were made on the day before IANI or the sham operation and on postoperative days 3, 5, 7, 14, and 28. PBMT was delivered for 7 consecutive days, with an energy density of 8 J/cm2. Behavioral analysis was performed to determine pain thresholds, and immunohistological staining was performed for the microglia marker Iba1 and astrocyte marker glial fibrillary acidic protein, which are observed in the spinal trigeminal nucleus. Results: Behavioral analysis showed that the pain threshold returned to the preoperative level on postoperative day 14 in the IANI+PBM group, but decreased starting from postoperative day 1 and did not improve thereafter in the IANI-PBM group (p ≤ 0.001). Immunological analysis showed that microglial and astrocyte cell counts were similar in the IANI+PBM group and IANI-PBM group shortly after IANI (day 3), but the expression area was larger (p ≤ 0.001) and hypertrophy of microglia and astrocyte cell bodies and end-feet extension (i.e., indicators of activation) were more prominent in the IANI+PBM group. Conclusions: PBMT after IANI prevented hyperalgesia and allodynia by promoting glial cell activation shortly after injury.

M2 macrophage-derived cathepsin S promotes peripheral nerve regeneration via fibroblast-Schwann cell-signaling relay

BACKGROUND

Although peripheral nerves have an intrinsic self-repair capacity following damage, functional recovery is limited in patients. It is a well-established fact that macrophages accumulate at the site of injury. Numerous studies indicate that the phenotypic shift from M1 macrophage to M2 macrophage plays a crucial role in the process of axon regeneration. This polarity change is observed exclusively in peripheral macrophages but not in microglia and CNS macrophages. However, the molecular basis of axonal regeneration by M2 macrophage is not yet fully understood. Herein, we aimed to identify the M2 macrophage-derived axon regeneration factor.

METHODS

We established a peripheral nerve injury model by transection of the inferior alveolar nerve (IANX) in Sprague-Dawley rats. Transcriptome analysis was performed on the injured nerve. Recovery from sensory deficits in the mandibular region and histological reconnection of IAN after IANX were assessed in rats with macrophage depletion by clodronate. We investigated the effects of adoptive transfer of M2 macrophages or M2-derived cathepsin S (CTSS) on the sensory deficit. CTSS initiating signaling was explored by western blot analysis in IANX rats and immunohistochemistry in co-culture of primary fibroblasts and Schwann cells (SCs).

RESULTS

Transcriptome analysis revealed that CTSS, a macrophage-selective lysosomal protease, was upregulated in the IAN after its injury. Spontaneous but partial recovery from a sensory deficit in the mandibular region after IANX was abrogated by macrophage ablation at the injured site. In addition, a robust induction of c-Jun, a marker of the repair-supportive phenotype of SCs, after IANX was abolished by macrophage ablation. As in transcriptome analysis, CTSS was upregulated at the injured IAN than in the intact IAN. Endogenous recovery from hypoesthesia was facilitated by supplementation of CTSS but delayed by pharmacological inhibition or genetic silencing of CTSS at the injured site. Adoptive transfer of M2-polarized macrophages at this site facilitated sensory recovery dependent on CTSS in macrophages. Post-IANX, CTSS caused the cleavage of Ephrin-B2 in fibroblasts, which, in turn, bound EphB2 in SCs. CTSS-induced Ephrin-B2 cleavage was also observed in human sensory nerves. Inhibition of CTSS-induced Ephrin-B2 signaling suppressed c-Jun induction in SCs and sensory recovery.

CONCLUSIONS

These results suggest that M2 macrophage-derived CTSS contributes to axon regeneration by activating SCs via Ephrin-B2 shedding from fibroblasts.

Pharmacological Management of Orofacial Pain

Orofacial pain is a category of complex disorders, including musculoskeletal, neuropathic and neurovascular disorders, that greatly affect the quality of life of the patient. These disorders are within the fields of dentistry and medicine and management can be challenging, requiring a referral to an orofacial pain specialist, essential for adequate evaluation, diagnosis, and care. Management is specific to the diagnosis and a treatment plan is developed with diverse pharmacological and non-pharmacological modalities. The pharmacological management of orofacial pain encompasses a vast array of medication classes and approaches. This includes anti-inflammatory drugs, muscle relaxants, anticonvulsants, antidepressants, and anesthetics. In addition, as adjunct therapy, different injections can be integrated into the management plan depending on the diagnosis and needs. These include trigger point injections, temporomandibular joint (TMJ) injections, and neurotoxin injections with botulinum toxin and nerve blocks. Multidisciplinary management is key for optimal care. New and safer therapeutic targets exclusively for the management of orofacial pain disorders are needed to offer better care for this patient population.

Morphological Studies to Identify the Nasopalatine and Inferior Alveolar Nerve Using a Special Head and Neck MRI Coil

OBJECTIVES

Procedures in oral and maxillofacial surgery bear a high risk of nerve damage. Three-dimensional imaging techniques can optimize surgical planning and help to spare nerves. The aim of this study was to investigate the diagnostic value of a 1.5 T magnetic resonance imaging (MRI) scanner with a dedicated dental signal amplification coil for the assessment of nerves in the oral cavity as compared with cone beam computed tomography (CBCT).

METHODS

Based on 6 predefined criteria, the assessability of the inferior alveolar and nasopalatine nerves in CBCT and MRI with a dedicated 4-channel dental coil were compared in 24 patients.

RESULTS

Compared with CBCT, MRI with the dental coil showed significantly better evaluability of the inferior alveolar nerve in the sagittal and axial plane and the nasopalatine nerve in the axial plane. In the sagittal plane; however, the assessability of the nasopalatine nerve was significantly better in CBCT as compared with MRI. Yet, pertaining to overall assessability, no significant differences between modalities were found.

CONCLUSIONS

In this pilot study, it can be reported that 1.5- T MRI with a dedicated dental coil is at least equivalent, if not superior, to CBCT in imaging nerve structures of the stomatognathic system.

CLINICAL RELEVANCE

Preoperative, 3-dimensional images are known to simplify and refine the planning and execution of operations in maxillofacial surgery. In contrast to computed tomography and CBCT, MRI does not cause radiation exposure while enabling visualization of all relevant hard and soft tissues and, therefore, holds an advantage over well-established techniques.

Complications and treatment errors in peri-implant hard tissue management

Bone augmentation procedures aim to regenerate the deficient alveolar ridge to properly place dental implants that are completely surrounded by bone. However, these are invasive and technically demanding surgeries that are not free of either complications or treatment errors. Careful patient selection and preparation is a mandatory process to reduce the rate of complications in bone regeneration procedures, irrespective of the technique used. It is important to assess the cost benefit of the intervention and to evaluate the potential impact on the patient's quality of life, especially in the elderly and medically compromised patients. Most common postoperative complications are wound dehiscences, which may be reduced, at least partially, by proper knowledge of the surgical technique and the craniofacial anatomy. Other complications that may appear are postoperative infections or nerve injuries. The aim of this narrative review is to summarize the best available scientific evidence on the incidence of complications, as well as the ideal strategies for their prevention and management. Depending on the severity of the complication, treatment approaches may vary and can include drug prescription or even surgical re-entries to remove exposed barrier membranes or contaminated bone grafts. Adequate prevention and proper management of complications associated with bone augmentation interventions are a requirement for clinicians carrying out these demanding procedures. A series of cases illustrating proper management of complications in different clinical scenarios is presented.

Is Surgical Repair With Nerve Allograft More Cost-Effective Than Non-Surgical Management for Persistent Trigeminal Neuropathy? Initial Assessment With Markov Model

PURPOSE

Persistent trigeminal neuropathy (PTN) is associated with high rates of depression, loss of work, and decreased quality of life (QoL). Nerve allograft repair can achieve functional sensory recovery in a predictable manner; however, it bears significant upfront costs. In patients suffering from PTN, is surgical repair with allogeneic nerve graft, when compared to non-surgical therapy, a more cost-effective treatment option?

MATERIALS AND METHODS

A Markov model was constructed with TreeAge Pro Healthcare 2022 (TreeAge Software, Massachusetts) to estimate the direct and indirect costs for PTN. The model ran for 40 years with 1-year-cycles on a 40-year-old model patient with persistent inferior alveolar or lingual nerve injury (S0 to S2+) at 3 months without signs of improvement, and without dysesthesia or neuropathic pain (NPP). The 2 treatment arms were surgery with nerve allograft versus non-surgical management. There were 3 disease states, functional sensory recovery (S3 to S4), hypoesthesia/anesthesia (S0 to S2+), and NPP. Direct surgical costs were calculated using the 2022 Medicare Physician Fee Schedule and verified with standard institutional billing practices. Non-surgical treatment direct costs (follow-up, specialist referral, medications, imaging) and indirect costs (QoL, loss of employment) were determined from historical data and the literature. Direct surgical costs for allograft repair were $13,291. State-specific direct costs for hypoesthesia/anesthesia were $2,127.84 per year, and $3,168.24 for NPP per year. State-specific indirect costs included decreased labor force participation, absenteeism, and decreased QoL.

RESULTS

Surgical treatment with nerve allograft was more effective and had a lower long-term cost. The incremental cost-effectiveness ratio was -10,751.94, indicating surgical treatment should be utilized based on efficiency and cost. With a willingness-to-pay threshold of $50,000, the net monetary benefits of surgical treatment are $1,158,339 compared to $830,654 for non-surgical treatment. With a standard threshold incremental cost-effectiveness ratio of 50,000, the sensitivity analysis shows that surgical treatment would remain the preferred choice based on efficiency even if surgical costs were doubled.

CONCLUSION

Despite high initial costs of surgical treatment with nerve allograft for PTN, surgical intervention with nerve allograft is a more cost-effective treatment option when compared to non-surgical therapy.

Is Presurgical Pain Intensity Related to Postoperative Recurrence of Post-Traumatic Trigeminal Neuropathic Pain?

PURPOSE

Post-traumatic trigeminal neuropathic pain (PTTNp) is a challenging condition to treat, and equally as challenging is the identification of surgical outcome variables to guide treatment. The study purpose was to determine if preoperative pain intensity was related to postoperative recurrence of PTTNp.

MATERIALS AND METHODS

This retrospective cohort study assessed subjects with preoperative PTTNp of either the lingual or inferior alveolar nerves who underwent elective microneurosurgery at a single institution. Two cohorts were established as follows: No PTTNp at 6 months (group 1); presence of PTTNp at 6 months (group 2). The primary predictor variable was the preoperative visual analog scale (VAS) score. The primary outcome variable was PTTNp (recurrence or no recurrence at 6 months). The demographic and injury characteristics of the groups were compared to assess whether they were similar using Wilcoxon rank analysis. Two-tailed Student's t-test was performed to analyze the difference in preoperative mean VAS scores. Multivariate multiple linear regression models were used to determine the association between the covariates on the outcomes of the primary predictor variable and the primary outcome variable. A P value of <.05 was considered statistically significant.

RESULTS

Forty-eight patients were included in the final analysis. There were 20 patients with no pain at 6 months and 28 with recurrence at 6 months following surgery. There was a significant difference in mean preoperative pain intensity between the two groups (P value .04). The mean preoperative VAS score in group 1 was 6.31 (standard deviation, 2.65), while the mean preoperative VAS score in group 2 was 7.75 (standard deviation, 1.95). Regression analysis showed that one covariate, the type of nerve injured, explained some variability of preoperative VAS score, but by only 16% (P value .005). Regression analysis also showed that two covariates, Sunderland classification and time to surgery, explained some of the variability of PTTNp at 6 months, by approximately 30% (P value .001).

CONCLUSION

This study showed that presurgical pain intensity level was related to postoperative recurrence in the surgical treatment of PTTNp. In patients with recurrence, the preoperative pain intensity was higher. Other factors, including time interval from injury to surgery, were also related to recurrence.

CBCT Evaluation of Buccolingual Orientation of Inferior Alveolar Canal in Mandibular Posterior Region for Implant Planning

Purpose

Inferior alveolar nerve (IAN) can be subjected to iatrogenic injury during implant surgical procedures. The purpose of this retrospective study was to identify the buccolingual orientation of IAN in posterior mandible as adjunct information for implant planning and to estimate ethnicity-, sex-, and side-related variations in Malaysian population. Material and Methods. A total of 121 CBCT images were viewed with eXamVision software. The buccolingual position of IAN was identified in the posterior region. Buccal bone width (B), canal thickness (C), and lingual bone width (L) were measured at the horizontal canal levels. Kruskal–Wallis H test and Friedman test were used to analyze the buccolingual position. One-way ANOVA was performed to evaluate the variations in B, C, and L values.

Results

Overall, most of the IANs were located on the lingual sides of the second molar regions (left: 71.9%; right: 71.1%) and at the centers of the first molar regions (left: 57.9%; right: 47.10%) and exited through the mental foramen before the second premolar regions. There was statistically significant difference in the buccolingual position of the IAN between the sexes in the left second premolar regions (P = 0.03). There was variation in B between the sexes in the left first molar regions (P = 0.01). Statistically significant differences in C and L were also found between different ethnic groups (P = 0.04). Between both sides, there were variations in C in the first molar regions (P < 0.001) and the second molar regions (P = 0.03).

Conclusion

From the second molar to the second premolar, the buccal bone width decreased while the lingual bone width increased. There were variations between ethnicities, sexes, and sides among Malaysians.

Post-traumatic Trigeminal Neuropathic Pain: Factors Affecting Surgical Treatment Outcomes

Post-traumatic trigeminal neuropathic pain (PTTNp) is a painful condition that may result from injury to the sensory division of the trigeminal nerve. Treatment of this condition is challenging and consensus on treatment to resolve neuropathic pain has yet to be standardized. Equally as challenging is the identification of surgical outcome variables to guide surgical treatment of PTTNp. This is partly due to the variability in pain characteristics, severity of nerve injury, location, and duration from injury to surgery. In those with neuropathic pain prior to microsurgical intervention, the incidence of neuropathic pain after microsurgical intervention is 67%. It is unclear why nerve repair surgery is effective in resolving or decreasing neuropathic pain in some patients, whereas it has no effect on pain relief in others. Psychological, medical, and age-related factors have been identified as risk factors for developing chronic post-surgical pain due to post-traumatic neuropathic pain. Two factors: injury to surgery time and preoperative visual analog scale score have recently been identified as variables that influence surgical outcomes in the treatment of PTTNp.

Effect of vitamin B complex administration on pain and sensory problems related to inferior alveolar nerve damage following mandibular implant placement surgery

Background. Inferior alveolar nerve damage can lead to mild to severe paresthesia and even facial pain. One of the treatments considered today for the reconstruction and treatment of damaged peripheral nerves is the use of vitamin supplements. This study aimed to evaluate the effect of vitamin B complex supplementation on pain and sensory problems following mandibular implant placement surgery. Methods. In this single-blind clinical trial, 46 patients applying for implant placement, who were eligible for the study, were evaluated. All the patients were examined for sensory facial injury and inferior alveolar nerve injury within 24 hours after implant placement. The nerve damage was recorded by AI (asymmetry index) in the initial examination. Patients who reported clinical and radiographic signs of nerve damage due to implant or drill impingement of the nerve canal were excluded from the study and promptly treated with anti-inflammatory protocols. Then the patients were randomly divided into control (n=23) and intervention (n=23) groups. Patients in the control group received routine treatment after implantation, and patients in the intervention group received vitamin B complex pills in addition to routine treatment. A placebo was used to eliminate the inductive effect of the drug in the control group. Follow-up of patients was performed at intervals of 14 days and 1, 2, and 3 months after treatment. Data analysis was performed using SPSS 24 and Kruskal-Wallis, Wilcoxon, and chi-squared tests. Results. In both groups, a decreasing trend in pain intensity was observed for up to three months. There were no significant differences between the mean pain intensity in the intervention and control groups at all the follow-up intervals. In both groups, a decrease in the rate of paresthesia was observed during the 3-month follow-up. The mean of paresthesia in the two groups was not significantly different at any follow-up interval. Conclusion. Vitamin B complex might not affect pain intensity and paresthesia after implant surgery.

Therapy of Neurophysiological Changes after Oral and Maxillofacial Surgery—A Systematic Review

Introduction: The purpose of this systematic review was to critically analyze the recent literature to present a guideline for management of neurophysiological changes after implant placement and oral and maxillofacial surgical procedures. Materials and methods: Three electronic databases and manual search approaches were used to identify relevant articles on neurophysiological changes. Only studies with a randomized controlled study design were included. Primary outcome was defined as the status of recovery and relief of pain states under various therapies. Two independent reviewers evaluated the data. Results: A total of eight studies from 2891 records identified met the inclusion criteria. Therapy options for patients with neurophysiological changes after implant placement and oral and maxillofacial surgery were low-level laser (LLL), stellate ganglion block (SGB), medication, and surgical removal of implants. Six studies dealt with LLL, providing a significant improvement in mechanical sensation. Only one study revealed the whole neurosensory profile including neuropathic pain states. All the included RCT studies presented at least one bias, and a considerable heterogeneity of the included studies was revealed. Conclusions: Reduced thermal sensation may be due to irritation of small fibers. LLL might help to improve nerve recovery.

Injuries of the Peripheral Mandibular Nerve, Evaluation of Interventions and Outcomes: A Systematic Review

Trigeminal nerve injuries are common and there is currently no consensus on both timing and type of intervention to achieve the best outcomes. A systematic review was performed to compare the outcomes of the many different types of therapeutic interventions for nerve injury. PubMed, EBSCO, and Cochrane Review databases were used to search for studies published from January 1, 2000 to December 31, 2019. Included studies detailed treatment of an injury to peripheral branches of the trigeminal nerve, either known transection or injury causing persistent alteration in sensation. The primary outcome was functional sensory recovery via the Medical Research Council scale. Twenty studies were included, detailing outcomes of 608 subjects undergoing intervention for 622 nerve injuries. Surgical interventions were able to achieve functional sensory recovery in approximately >80% or more of the subjects. There was heterogeneity among how procedures were performed, timing to intervention, and methods of measuring recovery. The data of this study supports the ability of surgical intervention to achieve functional sensory recovery in a significant number of subjects, and found evidence for better outcomes with intervention closer to the time of injury.

Analysis of the mandibular canal course using unsupervised machine learning algorithm

Objectives

Anatomical structure classification is necessary task in medical field, but the inevitable variability of interpretation among experts makes reliable classification difficult. This study aims to introduce cluster analysis, unsupervised machine learning method, for classification of three-dimensional (3D) mandibular canal (MC) courses, and to visualize standard MC courses derived from cluster analysis in the Korean population.

Materials and methods

A total of 429 cone-beam computed tomography images were used. Four sites in the mandible were selected for the measurement of the MC course and four parameters, two vertical and two horizontal parameters were measured per site. Cluster analysis was carried out as follows: parameter measurement, parameter normalization, cluster tendency evaluation, optimal number of clusters determination, and k-means cluster analysis. The 3D MC courses were classified into three types with statistically significant mean differences by cluster analysis.

Results

Cluster 1 showed a smooth line running towards the lingual side in the axial view and a steep slope in the sagittal view. Cluster 2 ran in an almost straight line closest to the lingual and inferior border of mandible. Cluster 3 showed the pathway with a bent buccally in the axial view and an increasing slope in the sagittal view in the posterior area. Cluster 2 showed the highest distribution (42.1%), and males were more widely distributed (57.1%) than the females (42.9%). Cluster 3 comprised similar ratio of male and female cases and accounted for 31.9% of the total distribution. Cluster 1 had the least distribution (26.0%) Distributions of the right and left sides did not show a statistically significant difference.

Conclusion

The MC courses were automatically classified as three types through cluster analysis. Cluster analysis enables the unbiased classification of the anatomical structures by reducing observer variability and can present representative standard information for each classified group.

Diagnosis and Management of Lingual Nerve Injuries

Injury to the lingual nerve is a well-recognized risk associated with certain routine dental and oral surgical procedures. The assessment and management of a patient with a traumatic lingual nerve neuropathy requires a logical and stepwise approach. The proper application and interpretation of the various neurosensory tests and maneuvers is critical to establishing an accurate diagnosis. The implementation of a surgical or nonsurgical treatment strategy is based not only on the established diagnosis, but also a multitude of variables including patient age, timing and nature of the injury, and the emotional or psychological impact.

Evaluation of Mental Foramen with Cone Beam Computed Tomography: A Systematic Review of Literature

Purpose

The aim of this systematic review is to assess whether the anatomy of mental foramen is precisely evaluable with cone beam computed tomography (CBCT) before implantation in humans.

Methods

A systematic review was carried out to evaluate the anatomy of mental foramen (size, position, symmetry, anterior loop, and accessory mental foramen or multiple mental foramina). According to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, an electronic search of three databases (Medline, Web of Science, and Cochrane Library) was undertaken until June 2020 and was supplemented by manual searching. Two reviewers will independently perform the processes of study inclusion, data extraction, and quality assessment. Systematic reviews, studies about children, and case reports were excluded. Only studies using CBCT to do preoperative evaluation were selected.

Results

From 728 potentially eligible articles, 72 were included in the qualitative analysis and quantitative synthesis. This systematic review provided an assessment of the anatomy of the mental foramen. The mental foramen was located mostly between the two premolars (between 50.4% and 61.95%) or apically to the second premolar (from 50.3% to 57.9%). The mean diameter of the mental foramen was bigger in males than in females; the difference between them could reach 0.62 mm. The anterior loop seemed to be longer in males (between 0.87 ± 1.81 and 7.25 ± 2.02 mm) than in females (between 0.81 ± 1.18 and 6.52 ± 1.63 mm) and with the presence of teeth (from 0.91 ± 1.18 to 2.55 ± 1.28 for dentate people and from 0.25 ± 0.61 to 2.40 ± 0.88 mm for edentate population). The anterior loop and the accessory mental foramina were detected more frequently with CBCT than panoramic X-ray: only between 0.0 and 48.6% AMFs detected with CBCT were also seen with panoramic images. Clinical Significance. The mental foramen (MF) is an important landmark for local anesthesia and surgical and implantology procedures. Its location, morphology, and anatomical variations need to be considered to avoid mental nerve injury. The aim of this review is to evaluate the mental foramen using CBCT through a systematic literature review to improve knowledge of this complex area for the clinician.

Anatomical Risk Factors of Inferior Alveolar Nerve Injury Association with Surgical Extraction of Mandibular Third Molar in Korean Population

The purpose of this study was to analyze the incidence and risk factors of possible inferior alveolar nerve (IAN) injury after extraction of the mandibular third molars. A total of 6182 patients were examined for 10,310 mandibular third molar teeth. Panoramic radiography and patients’ medical records were used to analyze age, gender, and impaction pattern of the mandibular third molar. Cone beam computed tomography (CBCT) was used to investigate the detailed pathway of the inferior alveolar nerve and evaluated the presence of symptoms of nerve damage after tooth extraction. In CBCT, 6283 cases (61%) of the inferior alveolar nerve were actually in contact with the root of the mandibular third molar. The correlation with the panoramic signs of root darkening (p < 0.001), root deflection (p < 0.001), interruption of the IAN (p < 0.001), diversion of the IAN (p < 0.001), and narrowing of the IAN (p < 0.001) had statistical significance. Of the 4708 patients who underwent surgical extraction, 31 (0.658%) complained of nerve damage. Among them, 30 patients (0.637%) complained of symptoms of inferior alveolar nerve damage, and 1 patient (0.02%) complained of symptoms of lingual nerve damage. There was a significant correlation with IAN injury in cases where the roots became dark at the IAN area (p = 0.018) and there was diversion of the IAN at the root area (p = 0.041). When the narrowing of the IAN and the lingual driving pathway of the inferior alveolar nerve appeared simultaneously in CBCT, the risk of IAN injury was high.

Characteristics of Mandibular Canal Branches Related to Nociceptive Marker

It is difficult to correlate the direction of mandibular canal branches (MCBs) with altered sensation in dental treatments. In contrast, calcitonin gene-related peptide (CGRP) is related to vasodilation, bone formation, and the interaction with the peripheral nervous system. Therefore, we investigated the detailed morphological characteristics of MCBs using cone-beam computed tomography (CBCT) and observation of the CGRP distribution around the MCB. The MCB measurements were evaluated using principal component analysis (PCA) to identify morphological correlations. A total of 168 sides of mandibles from 84 cadavers were analyzed in this study. Most of the MCBs were primarily in the direction of the clock model from X to XI in sagittal sections and XII to I in coronal sections of the mandible. The structure of the MCB was divided into the fine canal branch (60.4%, 223/369), partial branch (24.4%, 90/369), and no canal branch (15.2%, 56/369). PCA indicated that the measurement element with the MCB and its structures were correlated in contrast to tooth factors. Positive CGRP reactions were clearly observed in the no-canal branch group compared to other groups. These data provide useful suggestions for MCB dynamics and information for clinical dental treatment.

Pain complications of oral implants: Is that an issue?

The use of oral implants as a form of replacing missing teeth in partial or total edentulous patients is considered the gold standard in oral rehabilitation. Although considered a history of success in contemporary dentistry, surgical complications may occur, as excessive bleeding, damage to the adjacent teeth and mandibular fractures. Persistent pain and abnormal somatosensory responses after the surgery ordinary healing time are also potential problems and may lead to the development of a condition named posttraumatic trigeminal neuropathic pain (PTNP). Though relatively rare, PTNP has a profound impact on patient's quality of life. Appropriated previous image techniques, effective anaesthetic procedures and caution during the surgical procedure and implant installation are recommended for the prevention of this condition. In case of the PTNP, different management modalities, including antidepressant and membrane stabilizer medications, as well as peripheral strategies, as the use of topical medication and the botulin toxin are presented and discussed.

Performance of Schwann cell transplantation into extracted socket after inferior alveolar nerve injury in a novel rat model

An inferior alveolar nerve (IAN) injury is a common clinical problem that can affect a patients' quality of life. Cellular therapy has been proposed as a promising treatment for this injury. However, the current experimental models for IAN injury require surgery to create bone windows that expose the nerve, and these models do not accurately mimic human IAN injuries. Therefore, in this study, a novel experimental model for IAN injury has been established in rats. Using this model, the effects of Schwann cells and their role in the recovery from IAN injuries were investigated. Schwann cells were isolated from rat sciatic nerves and cultured. The first molar in the mandible was extracted and the IAN was immediately injured for 30 min by inserting an insect pin. Then, the Schwann cells or culture medium were transplanted into the extracted sockets of the cell and injury groups, respectively. After the surgery, the cell group displayed significantly increased sensory reflexes in response to mechanical stimulation, regenerated IAN width, and myelin basic protein-positive myelin sheaths when compared with the injury group. In conclusion, a novel animal experimental model for IAN injury has been developed that does not require the creation of a bone window to evaluate the impacts of cell transplantation and demonstrates that Schwann cell transplantation facilitates the regeneration of injured IANs.

The Trigeminal Nerve Injury

Trigeminal nerve branches are never far from the operating field of the oral and maxillofacial surgeon. Increasingly the surgeon is required to provide accurate diagnosis and grading of trigeminal nerve injury, and surgical management by oral and maxillofacial surgeons will become common. Although trauma and ablative procedures for head and neck pathology can cause injuries, dentoalveolar surgical procedures remain an important cause of injury to the fifth cranial nerve, with the third division being the main branch affected. Oral and maxillofacial surgeons should be aware of strategies of avoiding iatrogenic injury, and know when referral and surgical management are appropriate.

The reliability of surgeons to avoid traumatic insertion of dental implants into high-risk regions: a panoramic radiograph study

BACKGROUND

The posterior regions of the jaws usually represent a significant risk for implant surgery. A non-valid assessment of the available bone height may lead to either perforation of the maxillary sinus floor or encroachment of the inferior alveolar nerve and consequently to implant failure. This study aimed to evaluate the reliability of surgeon's decision in appraising the appropriate implant length, in respect to vital anatomical structures, using panoramic radiographs.

METHODS

Only implants that are inserted in relation to the maxillary sinus (MS) or the mandibular canal (MC) were enrolled (first premolars [1P], second premolars [2P], first molars [1M], and second molars [2M]). All preoperative panoramic radiographs were evaluated under standard conditions. The postoperative estimation (under/over) was determined depending on the available bone height (ABH) measured from the apical end of the implant to the floor of the MS and the roof of the MC using cone beam computed tomography (CBCT). Any complication or side effect that associated with overestimated implants insertion was recorded.

RESULTS

The study sample included 73 patients (predominantly females) who had consecutively received 148 implants, of which 68 were inserted in the posterior maxilla and 80 in the posterior mandible. Underestimation was recorded in 93.2% of the measurements. The remaining bone height after implants insertion was < 2 mm in the majority of underestimated cases (73.9%); they were significantly (P < 0.01) more than sites with remaining bone ≥ 2 mm (26.1%). In the posterior mandible, overestimation was significantly higher than posterior maxilla. Five cases with transient paresthesia were reported in the mandibular overestimated implants.

CONCLUSIONS

This study specified that surgeon's choice of implants length, based on panoramic radiographs, was reliable regarding the incapability to insert implants with further length in the majority of underestimated cases, the low percent of overestimated measurements, and the minor associated complications.

Incidence of neurosensory disturbance in mandibular implant surgery - A meta-analysis

Aim

Implantology has been widely accepted as the mainstay treatment for rehabilitating complete and partial edentulism. However, it is associated with some failures and complications, the most concerning being neurosensory disturbance. Although neurosensory disturbance has been extensively studied, the incidence and cause remains largely variable. Thus, the aim of this systematic review and meta-analysis was to evaluate the incidence, distribution, and recovery rate of neurosensory disturbance.

Settings and Design

This systematic review was conducted as per the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement. A structured literature review was conducted using the following databases: PubMed, Science Direct, Cochrane, Ovid, and Google Scholar for reports related to neurosensory disturbance experienced after implant placement in the mandible.

Statistical Analysis Used

Incidence and recovery rate for 100 person-years was calculated using the Poisson regression model. The risk difference of incidence between anterior and posterior implants was calculated with a random effects model.

Results

Electronic database search yielded 1589 articles; a total of nine articles were selected for the meta-analysis. The risk of neurosensory disturbance was estimated at 13.50/100 person-years (95% confidence interval (CI): 10.98-16.03), with a greater risk with anteriorly placed implants: -0.02 (95% CI: -0.21-0.16) (P = 0.05). The overall recovery rate was estimated at 51.30/100 person-years (95% CI: 31.2-71.4).

Conclusions

Within the limitations of the study, it can be concluded that mandibular implant placement is associated with a considerable risk of neurosensory disturbance. A large proportion of these patients present with spontaneous recovery; however, clinicians must take necessary precautions to avoid such complications. More randomized controlled trials are required to quantify the effect of factors leading to altered sensation during implant placement.

The anatomical relationship between the roots of erupted permanent teeth and the mandibular canal: a systematic review

PURPOSE

This study reviewed the literature on the position of the mandibular canal (MC) relative to the root apices (RA) of neighbouring teeth using cone beam computed tomography (CBCT).

METHODS

The authors searched the PubMed, Scopus, EBSCO Dentistry and Oral Sciences Source, Cochrane and Lilacs databases for relevant English-language articles with no year limitations published through January 25, 2018.

RESULTS

The search identified 888 articles, 12 of which met the inclusion criteria. Three groups were found based on the measuring method: the shortest distance from the RA to the MC, the vertical distance from the RA to the MC, or the distance from the RA to the superior cortical bone of the MC. In the first and second groups, the shortest distances to the canines, first premolars, second premolars, first molars, second molars, and third molars were 3.8 mm, 4.76 mm, 1.65 mm, 1.23 mm, 0.64 mm, and 1.28 mm, respectively. In the third group, the shortest distances to the second premolars, first molars, and second molars were 2.71 mm, 3.82 mm, and 1.4 mm, respectively.

CONCLUSIONS

The distance from the MC to the RA was generally shorter in females and younger people, with decreasing distances in patients over 60 years old, and depended on the tooth type.

TRIAL REGISTRATION

The protocol for this systematic review was registered on PROSPERO (CRD42018085478).

Quantitative and qualitative sensory testing results are associated with numbness rather than neuropathic pain in patients with post-implant trigeminal neuropathy: a cross-sectional pilot study

Purpose: This study aimed to characterize the sensory profile of patients with post-implant trigeminal neuropathy and identify the association between subjective symptoms and objective signs including psychophysical testing and radiographic imaging. This study further evaluated to the association between quantitative sensory testing (QST)/qualitative sensory testing (QualST) and the severity of nerve injury graded by radiographic imaging. Materials and methods: This retrospective study included 34 patients diagnosed with post-implant trigeminal neuropathy. Data on the neuropathic pain symptom inventory (NPSI), thermal and electric QST, bedside QualST, and cone beam computed tomography (CBCT) was collected and the association between these variables were analysed. Results: Numbness was the most common subjective symptom and evoked pain was the most frequent neuropathic pain. There was no significant correlation between negative and positive symptoms. Spearman's rank correlation analyses indicated that objective findings including QST/QualST correlated with a sensory loss profile rather than a gain of function profile. Moderate positive correlations between some positive symptoms and the score of QualST were observed. The Mann-Whitney U test showed that subjective symptoms did not differ according to the severity of nerve damage according to CBCT, but the electric QST and QualST was discriminative. Conclusions: This study suggests that QST/QualST associated with the severity of nerve damage according to CBCT might be useful in assessing numbness in patients with negative and positive symptoms after implant surgery, but may be of marginal utility in the evaluation of neuropathic pain within the limitation of this cross-sectional study with small sample size.

Prognosis in case of nerve disturbance after mandibular implant surgery in relation to computed tomography findings and symptoms

Purpose

The aim of this study was to evaluate the computed tomography (CT) imaging findings and clinical symptoms of patients who complained of neurosensory disturbances after mandibular implant surgery, and to investigate the relationships of these parameters with the prognosis for recovery.

Methods

CT scans were reviewed in 56 patients with nerve disturbance after mandibular implant surgery. Two oral radiologists classified the imaging findings into intrusion, contact, close, and separate groups according to the distance from the inferior border of the implant to the roof of the mandibular canal (MC). The symptoms of 56 patients were classified into 8 groups and the frequency of each group was investigated. Patients were categorized according to symptom improvement into no recovery and recovery groups, and the relationships of recovery with the CT classification and specific symptom groups were analyzed.

Results

Thirty-eight of the 56 nerve disturbance cases showed improvement. The close and separate groups in the CT classification had a strong tendency for recovery (90.9% and 81.8%, respectively) (P<0.05). Although the lowest recovery rate was found in the intrusion group, it was non-negligible, at 50%. The 6 patients with a worm crawling feeling all improved, while the 8 cases with a tightening sensation showed the lowest recovery rate, at 12.5%, and the symptom of a tightening sensation occurred only in the intrusion and contact groups.

Conclusions

The closer the implant fixture was to the MC on CT images, the less likely the patient was to recover. Regarding paresthesia symptoms, while a worm crawling feeling is thought to be a predictor of recovery, a tightening sensation appeared to be associated with a lower recovery rate.

Partial Explantation of Failed Dental Implants Placed in Mandibular Canal: A Case Report

One of the most important concerns during posterior mandibular implant placement is avoiding the mandibular canal. Nerve injury can be very disturbing to the patient, possibly causing mild paresthesia to complete anesthesia. Explantation of a dental implant that gas violated the mandibular canal is the most recommended treatment. However, an osseointegrated implant that placed in the mandibular canal can be left if the patient shows no symptoms. In this case report, we describe a technique to maintain the apexes of the implants while partially removing fractured osseointegrated implants previously placed in the mandibular canal.

Case-control study of mandibular canal branching and tooth-related inflammatory lesions

OBJECTIVES

Morphological variations of mandibular canals increase the risk of neurovascular damage and bleeding during surgical procedures by decreasing the predictability of the inferior alveolar neurovascular bundle location. To improve the predictability with such variations, the present study aimed to verify the possibility of a relationship between mandibular canal branches (MCBs) and tooth-related inflammatory lesions, using trough cone-beam computed tomography (CBCT) examinations.

METHODS

The sample comprised 150 age and sex-matched examinations (50 cases and 100 controls) from two databases. The CBCT examinations were grouped by the presence of MCBs starting in the mandibular body regions as the outcome variable. Tooth-related inflammatory lesions and measurements of gray levels in the posterior region of the alveolar ridge were assessed in both groups. A multiple logistic regression analysis was applied to verify the relationships between MCBs and independent variables (p < 0.05).

RESULTS

Occurrence of tooth-related inflammatory lesions increased the risk of MCBs in the mandibular body regions (p < 0.001; OR 11.640; 95% CI 4.327-31.311). High-contrast images had a weaker association with MCBs (p = 0.002; OR 1.002; 95% CI 1.002-1.003). The most frequent tooth-related inflammatory lesions in both groups were endodontic (34 lesions; 45.94% of the total lesions). Most of the tooth-related inflammatory lesions related to MCBs were endodontic (20 cases) and combined endodontic and periodontal inflammation (20 cases).

CONCLUSIONS

An association was observed between MCBs in the mandibular body regions and tooth-related inflammatory lesions. Inflammatory lesions of endodontic origin are most often associated with MCBs.

A randomized controlled trial comparing nerve block and mandibular infiltration techniques in posterior mandible implant surgeries

Background

To compare global surgical pain under nerve block and mandibular infiltration anesthesia techniques, and to evaluate pain during drilling and the distance to the mandibular canal in posterior mandible implant surgeries.

Material and Methods

A prospective, randomized, controlled, double-blind, clinical trial was conducted to compare nerve block (Group A) to mandibular infiltration (Group B) techniques for dental implant placement. Global surgical pain (VAS = visual analogue scale), pain during drilling or implant placement (MPQ = McGill pain questionnaire) and distance to the mandibular canal (Image J) were statically analyzed. Age, gender, anxiety levels, tooth to be replaced, implant size, adjacent teeth and duration of surgery were also analyzed.

Results

172 patients were included and 283 dental implants were analyzed. VAS values were significantly higher in Group B (p<0.05). In Group A, 99% of the surgeries were performed painlessly during drilling and implant placement, but in Group B, 11.6% of implant placements (17 implants) felt pain during these surgical steps. Mean distance to mandibular canal (3.8 mm, range: 0.0 to 7.0) in those 17 implants placed under mandibular infiltration was clinically and statistically similar to the mean distance (3.0 mm, range: 0.0 to 9.0) of 130 implants placed painless (p=0.10). Pain during drilling under mandibular infiltration was significantly associated with the duration of surgery (p<0.05) and to both adjacent teeth being present (p<0.05).

Conclusions

Although both techniques are safe and effective for placing implants in the posterior mandible, nerve block provides a more profound analgesia than mandibular infiltration. When placing implants under mandibular infiltration, as getting closer to the canal does not increase the feeling of pain, it is not recommended to use the presence of pain as a preventive resource to avoid inferior alveolar nerve injuries. Key words:Dental implant, mandibular infiltration anesthesia, nerve block, pain, nerve injury.

Use of cone beam computed tomography in implant dentistry: current concepts, indications and limitations for clinical practice and research

Diagnostic radiology is an essential component of treatment planning in the field of implant dentistry. This narrative review will present current concepts for the use of cone beam computed tomography imaging, before and after implant placement, in daily clinical practice and research. Guidelines for the selection of three-dimensional imaging will be discussed, and limitations will be highlighted. Current concepts of radiation dose optimization, including novel imaging modalities using low-dose protocols, will be presented. For preoperative cross-sectional imaging, data are still not available which demonstrate that cone beam computed tomography results in fewer intraoperative complications such as nerve damage or bleeding incidents, or that implants inserted using preoperative cone beam computed tomography data sets for planning purposes will exhibit higher survival or success rates. The use of cone beam computed tomography following the insertion of dental implants should be restricted to specific postoperative complications, such as damage of neurovascular structures or postoperative infections in relation to the maxillary sinus. Regarding peri-implantitis, the diagnosis and severity of the disease should be evaluated primarily based on clinical parameters and on radiological findings based on periapical radiographs (two dimensional). The use of cone beam computed tomography scans in clinical research might not yield any evident beneficial effect for the patient included. As many of the cone beam computed tomography scans performed for research have no direct therapeutic consequence, dose optimization measures should be implemented by using appropriate exposure parameters and by reducing the field of view to the actual region of interest.

Iatrogenic trigeminal post-traumatic neuropathy: a retrospective two-year cohort study

With the growing demand for dental work, trigeminal nerve injuries are increasingly common. This retrospective cohort study examined 53 cases of iatrogenic trigeminal nerve injury seen at the Department of Oral and Maxillofacial Surgery, University Hospitals of Leuven between 2013 and 2014 (0.6% among 8845 new patient visits). Patient records were screened for post-traumatic trigeminal nerve neuropathy caused by nerve injury incurred during implant surgery, endodontic treatment, local anaesthesia, tooth extraction, or specifically third molar removal. The patients ranged in age from 15 to 80years (mean age 42.1years) and 68% were female. The referral delay ranged from 1day to 6.5years (average 10months). The inferior alveolar nerve (IAN) was most frequently injured (28 cases), followed by the lingual nerve (LN) (21 cases). Most nerve injuries were caused during third molar removal (24 cases), followed by implant placement (nine cases) and local anaesthesia injuries (nine cases). Pain symptoms were experienced by 54% of patients suffering IAN injury, compared to 10% of patients with LN injury. Persistent neurosensory disturbances were identified in 60% of patients. While prevention remains the key issue, timely referral seems to be a critical factor for the successful treatment of post-traumatic neuropathy.

Magnetic resonance imaging-a diagnostic tool for postoperative evaluation of dental implants: a case report

OBJECTIVE

Compared with cone beam computed tomography (CBCT), magnetic resonance imaging (MRI) might be superior for the diagnosis of nerve lesions associated with implant placement.

STUDY DESIGN

A patient presented with unilateral pain associated with dysesthesia in the region of the right lower lip and chin after implant placement. Conventional orthopantomography could not identify an association between the position of the inferior alveolar nerve and the implant. For 3-dimensional display of the implant in relation to the surrounding anatomy, CBCT was compared with MRI.

RESULTS

MRI enabled the precise depiction of the implant position and its spatial relation to the inferior alveolar nerve, whereas the nerve position and its exact course within the mandible could not be directly displayed in CBCT.

CONCLUSION

MRI may be a valuable, radiation-free diagnostic tool for the visualization of intraoral hard and soft tissues, offering an objective assessment of nerve injuries by a direct visualization of the inferior alveolar neurovascular bundle.

Effect of Acupuncture on Post-implant Paresthesia

Paresthesia is defined as an alteration in local sensibility, associated with numbness, tingling, or unpleasant sensations caused by nerve lesions or irritation. It can be temporary or permanent. The treatment protocol for facial paresthesia is primarily based on the use of drugs and implant removal, which may not be completely effective or may require other risk exposure when there is no spontaneous regression. However, other therapeutic modalities such as acupuncture can be used. The aim of this study is to report a case of a patient with paresthesia of the inferior alveolar nerve and pain caused by an implant surgery performed 2 years earlier. The patient received acupuncture treatment during 4 months of weekly sessions. Six points were used: Large Intestine (LI4), Large Intestine (LI11), Stomach (ST36), Liver (LR3), Extra Head and Neck (E-HN-18), and Stomach (ST5). The visual analog scale was used before and after each session for the analysis of paresthesia and pain, together with assessment of the paresthesia by delimitation of the desensitized region of the skin and presented discomfort. Pain remission and reduction in the size of the paresthesia area occurred after four sessions.

At-home laser treatment of oral neuronal disorders: Case reports

The neuronal disorders occurring in the oral district are mainly anaesthesia, paraesthesia, hypoesthesia and hyperaesthesia and they may occur frequently after surgical procedures. Medical treatment depends on degree of severity of the nerve injury but, in every case, it must be immediately carried out to reduce immune inflammatory reaction. The aim of this report is to investigate the effectiveness in the recovery of the peripheral nerve lesions of a new laser device recently proposed by the commerce that, due to its reduced size and to be a class I laser according the ANSI classification, may be used at home by the patient himself. Three different cases were treated with this "at-home approach": complete resolution of symptomatology was obtained after laser treatment with a good compliance for the patient and without reporting any side effect. Key words:Laser, biomodulation, low level laser therapy, oral neuronal disorders, at-home treatment, paresthesia.