Injury of the Inferior Alveolar Nerve during Implant Placement: a Literature Review

Template based segmental mandibulectomy with nerve preservation and patient-specific PEEK plate reconstruction in a dog

A 7-year-old French Bulldog presented with an acanthomatous ameloblastoma affecting approximately 30% of the right mandibular body. We utilized a patient-specific 3D-printed surgical template to perform lateral fenestration of the mandible and elevation of the inferior alveolar nerve (IAN), facilitating nerve preservation during subsequent segmental mandibulectomy. The resulting critical-sized bone defect was anatomically stabilized using a patient-specific polyetheretherketone (PEEK) bridging plate. The recovery process was uneventful, with maintained occlusion and orofacial sensitivity.Similar to cases in humans with ameloblastoma, preserving orofacial sensitivity through the preservation of the inferior alveolar nerve seems feasible in dogs. Consequently, potential negative consequences of permanent regional denervation, which are unavoidable in traditional mandibulectomy, can be avoided. Bridging the ostectomy with a PEEK plate, offering advantages such as radiolucency, absence of imaging artifacts, and a modulus of elasticity similar to bone, proved to be functional in this canine patient, with no signs of complications observed up to the latest follow-up at 6 months.

Neurological Complications following Surgical Treatments of the Lower Molars

Aim

The current review aims to explore postoperative neurological complications in third molar extractive surgery.

Materials and Methods

The PRISMA protocols were followed when conducting this review. We found a total of 2,250 articles that matched our topic using the Boolean keywords, mandibular nerve complications AND oral surgery, from PubMed (1,083), Scopus (435), and Web of Science (732), with the filters of English language articles, time range January 1, 2003, to September 30, 2023, and human studies. After 762 duplicates were eliminated, there remained 1,488 articles. Eleven final articles were deemed of the highest relevance to our topic by eliminating articles in animals, non-English language, reviews, meta-analysis, and off-topic. A potential risk in the third molar extraction was temporary loss of sensibility often caused by mild compression or irritation of the mandibular nerve. This typically resolves within weeks or months, but in severe cases, recovery might take longer. Permanent loss of sensation can occur, indicating significant nerve damage and lasting effects on touch, temperature, or pain perception.

Conclusions

Various treatments exist for nerve damage, including low-level laser therapy, pain management medications, or physical therapy. While these therapies may improve neurosensory impairment, patients often report a decline in their quality of life.

Inferior alveolar nerve injury resulting from different implant rotary instruments: An ex vivo comparative study in human cadaveric mandibles

The present study aimed to evaluate the degree of nerve injury on inferior alveolar nerve (IAN) by different implant drills resulting from direct canal intrusion into inferior alveolar canal (IAC). A cadaveric study involving 7 human mandibles was performed to evaluate mechanical injury of canal enclosed IAN resulting from different drills. In group 1, osteotomies were created using different drills with 1 mm of intracanal intrusion, simulating accidental drill intrusion into canal. In group 2, drilling was stopped when the tip has breached into IAC, limited by tactile feedback of operator. The depth and width of nerve defects were assessed using optical coherence tomography. A significant difference in defect depth was found (p < 0.001) in group 1. A sinus lift reamer inflicted the least damage (0.068 ± 0.022 mm). It was also found that the mean defect depth was significantly different when a twist drill was used (p = 0.016). Sinus lift reamer can be used safely for osteotomy preparation in mandible when bone height is limited or when radiographic visualization of canal is poor. Bone corticalization around IAC does not provide adequate protection for IAN in the event of accidental intracanal intrusion.

Morphometric Analysis of the Mandibular Canal and Its Anatomical Variants in a Chilean Subpopulation: Cone Beam Computed Tomography Study

The inferior alveolar nerve (IAN), contained within the mandibular canal (MC), is a structure prone to damage in clinical and surgical procedures on the mandible. This study aimed to analyze the MC morphology and its anatomical variants in a Chilean subpopulation using cone beam computed tomography (CBCT). In total, 342 images from patients with the following parameters were observed: 120 kV, 9 mA, field of view 12 × 9 MC, and voxel size 0.12 mm. The average length of the MC recorded a mean value of 70.493 ± 4.987 mm on the right side and 70.805 ± 5.177 mm on the left side. The location of the mental foramen (MF) was most frequently found between the mandibular first and second premolar. The greatest bone thickness was found at the level of the basilar border of the 2MPM. The root closest to the MC was distal from the mandibular second molar. The lowest thickness was in the lingual area at 1MM. The prevalence of the anterior loop (AL) (61.5%) and the retromolar canal (RC) (17.5%) showed no significant differences between men and women. The results obtained showed that the morphology of the MC in the Chilean subpopulation can vary.

Salvage of Iatrogenic Sciatic Nerve Injury Caused by Operatively Treated Acetabular Fractures: Two Cases and Literature Review

BACKGROUND

While sciatic nerve injury has been described as a complication of acetabular fractures, iatrogenic nerve injury remains sparsely reported. This study aims to assess iatrogenic sciatic nerve injuries occurring during acetabular fracture surgery, tracking their neurological recovery and clinical outcomes, and investigating any correlation between recovery and the severity of neurologic injury to facilitate physicians in providing prediction of prognosis.

CASE PRESENTATION

We present two cases of male patients, aged 56 and 22, who developed sciatic palsy due to iatrogenic nerve injury during acetabular fracture surgery. Iatrogenic sciatic nerve injury resulted from operatively treated acetabular fractures. Surgical exploration, involving internal fixation removal and nerve decompression, successfully alleviated symptoms in both cases postoperatively. At the latest follow-up, one patient achieved full recovery with excellent function, while the other exhibited residual deficits at the L5/S1 root level along with minimal pain.

CONCLUSION

Sciatic nerve injury likely stemmed from reduction techniques and internal fixation procedures for the posterior column, particularly when performed with the hip flexed, thereby placing tension on the sciatic nerve. Our case reports underscore the significance of liberal utilization of electrophysiologic examinations and intraoperative monitoring for the prediction of prognosis. Surgical exploration, encompassing internal fixation removal and nerve decompression, represents an effective intervention for resolving sciatic palsy, encompassing both sensory neuropathy and motor symptoms.

Identification of the Incisive Branch of the Inferior Alveolar Nerve of Edentulous Mandibles Using Cone-Beam Computerized Tomography

This study explored the average length of the incisive branch (IB) of the inferior alveolar nerve on cone-beam computerized tomography (CBCT) with regard to patient demographics in patients with edentulous mandibles. CBCT was used in a retrospective study of edentulous mandibles to assess the presence and anatomical variation for the IB. Three independent observers measured bilateral IB lengths. In addition to demographics, IB length and port of exit data were obtained. A 1-way analysis of variance was used to test whether IB length varied by sex or port of exit, and a standard Pearson correlation was used to test for IB length and age significance, with a significance level of P < .05. Intraclass correlation coefficients showed significant agreement in IB length across all observers. No significant difference was noted between the exit port and IB length. An important effect was reported for sex, indicating women have generally shorter IB lengths (9.43 ± 3.99 vs 10.55 ± 3.92). There was a significant correlation with age, but the relationship was weak. Edentulous mandibles have an altered anatomic landscape, and establishing predictive IB dimensions aids practitioners in surgical planning.

Mandibular canal assessment in dentate and edentulous ridges of 400 Iraqi Arab and Kurdish populations using cone beam computed tomography

Objectives

This study aims to compare differences in mandibular canal (MC) location between dentate and edentulous ridges, in the second premolar region as well as the first, second, and third molar regions using cone beam computed tomography (CBCT) of Arabic and Kurdish Iraqi populations.

Materials and Methods

CBCT images of 400 subjects (200 Arabs, 200 Kurds) were collected from radiological archives. RadiAnt DICOM software (Medixant, Poland) was used for image analyses. Measurements were performed from MC to buccal and lingual alveolar crests and to buccal, lingual, and inferior aspect of the mandible for both dentate and edentulous ridges. Additionally, distance to the most superior aspect of residual edentulous ridge were performed. Independent t-test and Mann-Whitney U Test were performed utilising SPSS v.26.

Results

Distances from MC to buccal and lingual alveolar crests were consistently lower in edentulous ridge compared to dentate ridge across all teeth regions. Distances to lingual and inferior border of the mandible were higher in edentulous ridge compared to dentate ridge of all teeth regions. Distances to buccal surface of the mandible varies with fluctuations of dentate and edentulous ridges displaying higher measurements. Distance to superior aspect of residual edentulous ridge revealed mean values in the range of 13.45 to 15.69 mm in Arabs and 13.96 to 16.37 mm in Kurds.

Conclusions

Discrepancy in vertical position of MC was observed between dentate and edentulous ridges within Arab and Kurd populations. Horizontal position of MC was unaffected by tooth loss and found to be closer to lingual surface of all molars. The residual alveolar ridge was sufficient to accommodate the common length and width of dental implants.

Clinical significance

The findings could play a crucial role in planning surgical interventions of the mandible, helping to prevent complications that might arise due to inadequate preoperative assessments.

Primary Stability of Implants Inserted into Polyurethane Blocks: Micro-CT and Analysis In Vitro

The approach employed for the site preparation of the dental implant is a variable factor that affects the implant's primary stability and its ability to integrate with the surrounding bone. The main objective of this in vitro study is to evaluate the influence of different techniques used to prepare the implant site on the primary stability of the implant in two different densities of artificial bone.

MATERIALS AND METHODS

A total of 150 implant sites were prepared in rigid polyurethane blocks to simulate two distinct bone densities of 15 pounds per cubic foot (PCF) and 30 PCF, with a 1-mm-thick simulated cortex. The implant sites were equally distributed among piezoelectric surgery (PES), traditional drills (TD), and black ruby magnetic mallet inserts (MM). Two methods have been employed to evaluate the implant's primary stability, Osstell and micro-tomography.

RESULTS

In the present study, we observed significant variations in the implant stability quotient (ISQ) values. More precisely, our findings indicate that the ISQ values were generally higher for 30 PCF compared to 15 PCF. In terms of the preparation technique, PES exhibited the greatest ISQ values, followed by MM, and finally TD. These findings corresponded for both bone densities of 30 PCF (PES 75.6 ± 1.73, MM 69.8 ± 1.91, and TD 65.8 ± 1.91) and 15 PCF (PES 72.3 ± 1.63, MM 62.4 ± 1.77, and TD 60.6 ± 1.81). By utilizing Micro-CT scans, we were able to determine the ratio of the implant occupation to the preparation site. Furthermore, we could calculate the maximum distance between the implant and the wall of the preparation site. The findings demonstrated that PES had a higher ratio of implant to preparation site occupation, followed by TD, and then the MM, at a bone density of 30 PCF (PES 96 ± 1.95, TD 94 ± 1.88, and MM 90.3 ± 2.11). Nevertheless, there were no statistically significant differences in the occupation ratio among these three approaches in the bone density of 15 PCF (PES 89.6 ± 1.22, TD 90 ± 1.31, and MM 88.4 ± 1.17). Regarding the maximum gap between the implant and the site preparation, the smallest gaps were seen when TD were used, followed by MM, and finally by PES, either in a bone density 15 PCF (PES 318 ± 21, TD 238 ± 17, and MM 301 ± 20 μm) or in a bone density 30 PCF (PES 299 ± 20, TD 221 ± 16, and MM 281 ± 19 μm). A statistical analysis using ANOVA revealed these differences to be significant, with p-values of < 0.05.

CONCLUSION

The outcomes of this study indicate that employing the PES technique and osteo-densification with MM during implant insertion may enhance the primary stability and increase the possibility of early implant loading.

Clinical insights into traumatic injury of the inferior alveolar and lingual nerves: a comprehensive approach from diagnosis to therapeutic interventions

OBJECTIVES

This scoping review explores the risk and management of traumatic injuries to the inferior alveolar and lingual nerves during mandibular dental procedures. Emphasizing the significance of diagnostic tools, the review amalgamates existing knowledge to offer a comprehensive overview.

MATERIALS AND METHODS

A literature search across PubMed, Embase, and Cochrane Library informed the analysis.

RESULTS

Traumatic injuries often lead to hypo-/anesthesia and neuropathic pain, impacting individuals psychologically and socially. Diagnosis involves thorough anamnesis, clinical-neurological evaluations, and radiographic imaging. Severity varies, allowing for conservative or surgical interventions. Immediate action is recommended for reversible causes, while surgical therapies like decompression, readaptation, or reconstruction yield favorable outcomes. Conservative management, utilizing topical anesthesia, capsaicin, and systemic medications (tricyclic antidepressants, antipsychotics, and serotonin-norepinephrine-reuptake-inhibitors), proves effective for neuropathic pain.

CONCLUSIONS

Traumatic nerve injuries, though common in dental surgery, often go unrecorded. Despite lacking a definitive diagnostic gold standard, a meticulous examination of the injury and subsequent impairments is crucial.

CLINICAL RELEVANCE

Tailoring treatment to each case's characteristics is essential, recognizing the absence of a universal solution. This approach aims to optimize outcomes, restore functionality, and improve the quality of life for affected individuals.

Do metal artifact reduction algorithms influence the detection of implant-related injuries to the inferior alveolar canal in CBCT images?

BACKGROUND

The routine application of dental implants for replacing missing teeth has revolutionized restorative and prosthetic dentistry. However, cone beam computed tomography (CBCT) evaluations of structures adjacent to the implants are limited by metal artifacts. There are several methods for reducing metal artifacts, but this remains a challenging task. This study aimed to examine the effectiveness of metal artifact reduction (MAR) algorithms in identifying injuries of implants to the inferior alveolar canal in CBCT images.

METHOD

In this in vitro study, mono-cortical bone windows were created and the inferior alveolar canal was revealed. Using 36 implants, pilot drill and penetration damage of the implant tip into the canal was simulated and compared to the control implants with distance from the canal. CBCT images were evaluated by four experienced observers with and without the MAR algorithm and compared to direct vision as the gold standard. The values of accuracy, sensitivity, and specificity were obtained and compared by receiver operating characteristic (ROC) curve (α = 0.05).

RESULT

The area under the ROC curve values for detection of pilot drill injuries varied between 0.840-0.917 and 0.639-0.854 in the active and inactive MAR conditions, respectively. The increase in ROC area was only significant for one of the observers (P = 0.010). For diagnosing penetrative injuries, the area under the ROC curve values was between 0.990-1.000 and 0.722-1.000 in the active and inactive MAR conditions, respectively. The improvement of ROC curve values in active MAR mode was only significant for one of the observers (P = 0.006).

CONCLUSION

Activation of MAR improved the diagnostic values of CBCT images in detecting both types of implant-related injuries to the inferior alveolar canal. However, for most observers, this increase was not statistically significant.

Neurological Complications of Local Anesthesia in Dentistry: A Review

Local anesthesia is a technique that temporarily desensitizes a specific body area, typically for a surgical procedure, dental work, or pain management. It is described as a sensation loss in a specific area of the body due to depression of excitation in the nerve endings or due to the inhibition of the conduction process within the peripheral nerves. It allows for safer and more comfortable medical procedures, reducing the need for general anesthesia and facilitating faster recovery. Local anesthesia is generally safe, but like any medical intervention, it carries potential risks and side effects. The complications related to local anesthetics can be assessed in terms of neurological, vascular, local, systemic, and neurological. In this review article, we discussed the neurological complications of local anesthesia related to the ophthalmic nerve, maxillary nerve, mandibular nerve, branches of the trigeminal nerve, and facial nerve. These include diplopia, ptosis, paralysis of the eye, blindness, paresthesia, trismus, soft tissue lesions, edema, hematoma, facial blanching, infection, allergy, overdose, neuralgia, facial palsy, etc.

The Influence of Slice Thickness, Sharpness, and Contrast Adjustments on Inferior Alveolar Canal Segmentation on Cone-Beam Computed Tomography Scans: A Retrospective Study

This retrospective study aims to investigate the impact of cone-beam computed tomography (CBCT) viewing parameters such as contrast, slice thickness, and sharpness on the identification of the inferior alveolar nerve (IAC). A total of 25 CBCT scans, resulting in 50 IACs, were assessed by two investigators using a three-score system (good, average, and poor) on cross-sectional images. Slice thicknesses of 0.25 mm, 0.5 mm, and 1 mm were tested, along with varying sharpness (0, 6, 8, and 10) and contrast (0, 400, 800, and 1200) settings. The results were statistically analyzed to determine the optimal slice thickness for improved visibility of IAC, followed by evaluating the influence of sharpness and contrast using the optimal thickness. The identified parameters were then validated by performing semi-automated segmentation of the IACs and structure overlapping to evaluate the mean distance. Inter-rater and intra-rater reliability were assessed using Kappa statistics, and inferential statistics used Pearson's Chi-square test. Inter-rater and intra-rater reliability for all parameters were significant, ranging from 69% to 83%. A slice thickness of 0.25 mm showed consistently "good" visibility (80%). Sharpness values of zero and contrast values of 1200 also demonstrated high frequencies of "good" visibility. Overlap analysis resulted in an average mean distance of 0.295 mm and a standard deviation of 0.307 mm across all patients' sides. The study revealed that a slice thickness of 0.25 mm, zero sharpness value, and higher contrast value of 1200 improved the visibility and accuracy of IAC segmentation in CBCT scans. The individual patient's characteristics, such as anatomical variations, decreased bone density, and absence of canal walls cortication, should be considered when using these parameters.

Management of post-implant inferior alveolar neuropathy, utilizing autologous fibrin glue, concentrated growth factors and enriched bone graft matrix-A case report with 5 years follow-up

This case report explains meticulous management of 5 year old, inferior alveolar nerve neuropathy, following placement of dental implants in the mandible. The imperative situation was that 'implants placed were not in contact with the nerve, but triggered neuralgic pain'. The objective of the treatment was to identify, and eliminate the causative factor, and to promote nerve regeneration, with pain relief. Treatment protocol and inferior alveolar nerve [IAN] sensory function evaluation were done following 'Inferior Alveolar Nerve Injury during Dental Implant Placement Surgery Protocol' [IANIDIS-Protocol]. Impregnation of autologous concentrated growth factors and enriched bone graft matrix [Sticky BoneTM], at the surgical site, aided effective hard and soft tissue regeneration, restoring comfort to the patient.

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.

The nature of malpractice claims related to nerve damage after dental implants insertion in Israel during 2005-2020: A descriptive study

INTRODUCTION

Dental implant placement is a routine practice in dentistry, with a possible uncommon risk of neurosensory injury. The present study analyzed all dental implant claims involving sensory nerve disturbances between 2005 and 2020 in Israel. The study was conducted to understand implant risk management better and improve the patient's safety.

MATERIALS AND METHODS

All legal claims registered by Medical Consultant International (MCI) involving nerve damage claims between 2005 and 2020 were included in the study. The data included demographic details such as age, sex, event date, claim delivery date, and treatment settings. Information on the nerve damage included the damaged nerve, side of injury, and the number of implants performed in the same surgery.

RESULTS

There were 218 claims regarding nerve damage out of 1154 claims for dental implant therapy. The mean age for nerve damage claims was 54.1 ± 11 years. There were more female than male claims (p = 0.02), with 87% of cases concerning damage to the inferior alveolar nerve (p < 0.0001), out of those molar areas being more frequently involved in nerve damage (64.3%, p < 0.0001). The left side was 1.4 times more frequent than the right side (p = 0.043). The risk for nerve injury was 7.4 times higher when placing multiple implants compared to single dental implant (p < 0.0001).

CONCLUSIONS

Clinicians should be aware that placement of multiple implants, left-side implant placement, and patient gender may increase risk for a malpractice claim for neurosensory disturbances.

Design of electrical impedance spectroscopy sensing surgical drill using computational modelling and experimental validation

Electrical Impedance Spectroscopy (EIS) sensing surgical instruments could provide valuable and real-time feedback to surgeons about hidden tissue boundaries, therefore reducing the risk of iatrogenic injuries. In this paper, we present an EIS sensing surgical drill as an example instrument and introduce a strategy to optimize the mono-polar electrode geometry using a finite element method (FEM)-based computational model and experimental validation. An empirical contact impedance model and an adaptive mesh refinement protocol were developed to accurately preserve the behaviour of sensing electrodes as they approach high impedance boundaries. Specifically, experiments with drill-bit, cylinder, and conical geometries suggested a 15%-35% increase in resistance as the sensing electrode approached a high impedance boundary. Simulations achieved a maximum mean experiment-to-simulation mismatch of +1.7% for the drill-bit and +/-11% range for other electrode geometries. The simulations preserved the increase in resistance behaviour near the high impedance boundary. This highly accurate simulation framework allows us a mechanism for optimizing sensor geometry without costly experimental evaluation.

Dual-Stage Deeply Supervised Attention-Based Convolutional Neural Networks for Mandibular Canal Segmentation in CBCT Scans

Accurate segmentation of mandibular canals in lower jaws is important in dental implantology. Medical experts manually determine the implant position and dimensions from 3D CT images to avoid damaging the mandibular nerve inside the canal. In this paper, we propose a novel dual-stage deep learning-based scheme for the automatic segmentation of the mandibular canal. In particular, we first enhance the CBCT scans by employing the novel histogram-based dynamic windowing scheme, which improves the visibility of mandibular canals. After enhancement, we designed 3D deeply supervised attention UNet architecture for localizing the Volumes Of Interest (VOIs), which contain the mandibular canals (i.e., left and right canals). Finally, we employed the Multi-Scale input Residual UNet (MSiR-UNet) architecture to segment the mandibular canals using VOIs accurately. The proposed method has been rigorously evaluated on 500 and 15 CBCT scans from our dataset and from the public dataset, respectively. The results demonstrate that our technique improves the existing performance of mandibular canal segmentation to a clinically acceptable range. Moreover, it is robust against the types of CBCT scans in terms of field of view.

Prevalence of dental implant positioning errors: A cross-sectional study

Purpose

This study evaluated the prevalence of dental implant positioning errors and the most frequently affected oral regions.

Materials and Methods

A sample was obtained of CBCT images of 590 dental implants from 230 individuals who underwent diagnosis at a radiology center using cone-beam computed tomography from 2017 to 2020. The following variables were considered: thread exposure, violation of the minimum distance between 2 adjacent implants and between the implant and tooth, and implant contact with anatomical structures. Descriptive data analysis and the Pearson chi-square test (P<0.05) were performed to compare findings according to mouth regions.

Results

Most (74.4%) of the 590 implants were poorly positioned, with the posterior region of the maxilla being the region most frequently affected by errors. Among the variables analyzed, the most prevalent was thread exposure (54.7%), followed by implant contact with anatomical structures, violation of the recommended distance between 2 implants and violation of the recommended distance between the implant and teeth. Thread exposure was significantly associated with the anterior region of the mandible (P<0.05). The anterior region of the maxilla was associated with violation of the recommended tooth-implant distance (P<0.05) and the recommended distance between 2 adjacent implants (P<0.05). Implant contact with anatomical structures was significantly more likely to occur in the posterior region of the maxilla (P<0.05).

Conclusion

Many implants were poorly positioned in the posterior region of the maxilla. Thread exposure was particularly frequent and was significantly associated with the anterior region of the mandible.

Novel and accurate 3D-Printed surgical guide for mandibular reconstruction with integrated dental implants

PURPOSE

Patients with mandibular defects due to trauma or infiltrated disease are in a need of functional mandibular implants that will completely restore the function of their lower jaw. One of the most important roles of well-functioning jaw is mastication, a complex mechanism. A conventional approach used in oral and maxillofacial surgery accomplish this aim via two major surgeries- mandibular reconstruction and surgical placement of dental implants. Little work has been done on combining the two surgeries into with using Additive Manufacturing (AM) and digital planning.

MATERIAL AND METHODS

This case study offers a mandibular implant design solution with pre-positioned dental implants that can reduce the requirement to only one surgery. Mandibular implant was designed using 3-Matic software (Materialise, Belgium). Positions for dental implants were restoratively-driven and planned on the designed mandibular implant in Blue Sky Plan 4 software (Blue Sky Bio, USA) and placed prior to mandibular reconstruction using a 3D-printed surgical guide. Finite Element Analysis (FEA) was used to evaluate the mechanical behaviour of the 3D-printed surgical guide during dental implant placement.

RESULTS

The surgical guide was fabricated using SLA and stress distribution was evaluated in ANSYS Workbench FEM software (Ansys Inc Swanson, Houston, USA). Results showed that the designed surgical guide can withstand the forces occurring during the surgery.

CONCLUSION

The proposed method substantially reduces the surgical procedure and recovery time, increases the accuracy, and allows for a predictable restorative solution that can be visualised from the beginning.

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.

Sensory Changes Related to Dental Implant Placement: A Scoping Review

AIMS

To perform a scoping review of the literature to elucidate the occurrence of nerve damage related to dental implant placement and the factors causing the sensory changes.

METHODS

An extensive electronic search was conducted using the Cochrane Library, Medline via Ovid, PubMed, Wiley Online, Science Direct, CINAHL, and the Google Scholar databases from the year 1950 to 2020.

RESULTS

The search resulted in 1,067 articles, out of which 76 were selected for this review. The articles were categorized as literature review articles, retrospective studies, prospective studies, and case series/case reports. Altogether, 2,526 subjects were assessed retrospectively, with 5.27% transient and 1.39% persistent sensory changes, and a cohort of 2,750 subjects were followed prospectively, with 6.22% transient and 1.31% persistent sensory changes. A total of 336 subjects were enrolled in various case reports and case series, with 5.95% transient sensory changes and 84.52% persistent neurosensory changes. The articles included were not of high quality and have variations in their study designs and reporting procedures, with limited sensory change data to include in this study.

CONCLUSION

After surgical placement of dental implants in 5,612 patients, the incidence of transient sensory changes was 5.63%, and the incidence of persistent sensory changes was 6.33%. Factors affecting the incidence were: mandibular location of the implant, with the inferior alveolar nerve as the most commonly affected nerve. The common symptoms reported were paresthesia and dysesthesia. Age and gender were among other factors, for which data were not available in all the articles.

Effect of delayed photobiomodulation therapy on neurosensory recovery in patients with mandibular nerve neurotmesis following traumatic mandibular fracture: A randomized triple-blinded clinical trial

INTRODUCTION

There is a possibility of neurotmesis of the inferior alveolar nerve (IAN) in mandibular fractures, which leads to neurosensory impairment. In this study, we aimed to investigate the efficacy of photobiomodulation therapy (PBMT) in patients with neurotmesis following trauma and mandibular fracture.

MATERIALS AND METHODS

This triple-blind randomized trial was carried out on patients who suffered neurotmesis of the IAN following mandibular angle and body fracture at least for 6 months. In the intervention group, laser irradiation was applied with a low-level GaAlAs diode laser (continuous wave of 810 nm wavelength, power of 200 mW, and energy density of 12-14 J/cm²). In the control group, the laser probe was turned off and placed on the affected area. LLLT was done for 12 sessions (2 times/week for 6 weeks). Light touch sensations, two-point discrimination, thermal discrimination (cold and warm stimulus), electric pulp test (EPT), and oral health impact profile (OHIP)-14 questionnaire were performed before the intervention, immediately after each PBMT session, and after 3, 6, 9 and 12 months.

RESULTS

In both groups, 3 and 23 patients were female and male, respectively. The results showed significantly improved light (cotton swab), light (wooden cotton swab), and sharp (dental needle) touch sensations, and two-point discrimination test in the PBMT group after the 10th, 11th, 10th, and 10th session, respectively. Two-way repeated measure ANOVA revealed that the trend of light touch sensation with cotton swab and two-point discrimination test was statistically significant (p-value = 0.002 and 0.001, respectively). The results of OHIP-14 test showed a significantly higher mean in the PBMT group 3 months after PBMT. There was no statistically significant difference in EPT and thermal discrimination tests regarding the patients' group.

CONCLUSION

PBMT could be an effective treatment for late post-traumatic nerve neurotmesis following a traumatic mandibular fracture.

Curriculum of gross anatomy education in Korean dental hygiene programs: Perceptions of clinical dental hygienists

It is essential for dental hygienists to have basic knowledge of gross anatomy to provide efficient treatment. However, gross anatomy course is relatively neglected due to their disparity from actual clinical dental practice. This study aimed to propose an effective dental hygiene gross anatomy curriculum that reflects the opinions of professional clinical dental hygienists. The study had an online-based cross-sectional design and the survey was distributed to clinical dental hygienists via social networks (n = 200). The questionnaire consisted of questions on the utilization of anatomical knowledge in clinical practice, opinions on the contents and methods of gross anatomy education, and general characteristics. The present study found that 186 (93%) used anatomical knowledge at an above-average level. Qualitative analysis indicated that dental implant surgery, radiography, and extraction were the clinical procedures that required the most anatomical knowledge. The clinical dental hygienists answered that the most-necessary knowledge is that of the mandibular nerve, followed by that on the temporomandibular joint, mandible, maxilla, maxillary nerve, and masticatory muscle. The methods proposed to improve gross anatomy education were (in decreasing order of importance) using videos or photographs (X-rays, CT, MRI, etc.), integrating education with clinical subjects, and using a three-dimensional visualization program. Higher education levels of respondents have increased their tendency to believe that the contents and methods of the presented education were necessary. Dental hygienists who utilized anatomical knowledge more often tended to be had a greater appreciation of the necessity of all educational contents and methods.

Bioimpedance Sensing Surgical Drill - In Vivo Porcine Model

Surgical drilling to place dental implants in the mandible and maxilla is associated high risk of iatrogenic injuries to inferior alveolar nerve and maxillary sinus. Real-time tissue margin sensing at the drill-tip using electrical impedance spectroscopy (EIS) could reduce this risk by providing feedback to surgeons. Studies with saline analogues, ex-vivo tissues, in-situ tissues and computer models have been previously conducted to evaluate these impedance sensors. Understanding in-vivo electrical properties of tissues in the mandible and maxilla is critical to further develop the sensor and tissue margin sensing algorithms. In this paper, we propose an in-vivo animal model using pigs and discuss methods to test the sensor. Intra-operative imaging and optical tracking systems to assist in surgical navigation are described. The process of registering imaging and tracking information to localize impedance measurement sites within the anatomy are detailed. Results from one in-vivo case of drilling through the mandible are presented and discussed. Clinical Relevance- This model is crucial for characterizing in-vivo electrical properties of mandibular and maxillary tissues encountered during dental implant surgical drilling and for translating bioimpedance sensing drill technology to clinical space.

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.

Complications in bone-grafting procedures: Classification and management

Bone-regenerative interventions aiming to restore deficient alveolar ridges, such as the use of block grafts or through the application of guided bone-regeneration principles, have reported positive outcomes in the published scientific literature. These interventions, however, are invasive, and hence, intraoperative and/or postoperative complications may occur. The types of complications and their severity may vary from the exposure of the biomaterial (membrane or graft) to postsurgical infections, neurosensorial disturbances, occurrence of hemorrhage, and pain, etc. The aim of the present narrative review was to search the available scientific evidence concerning the incidence of these complications, their effect on treatment outcomes, their clinical management and, finally, strategies aimed at prevention. Exposure of the barrier membrane or the block graft is the most common complication associated with oral regenerative interventions. To manage these complications, depending on the extent of the exposure and the presence or absence of concomitant infections, therapeutic measures may vary, from the topical application of antiseptics to the removal of the barrier membrane or the block graft. Regardless of their treatment, the occurrence of these complications has been associated with patient selection, with compliant patients (eg, nonsmokers) having a lower reported incidence of complications. Similarly, surgical factors such as correct flap elevation and a tensionless closure are of obvious importance. Finally, to prevent the incidence of complications, it appears prudent to utilize whenever possible less invasive surgical interventions.

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.

Expect the unexpected: The course of the inferior alveolar artery - Preliminary results and clinical implications

INTRODUCTION

The anatomical position of the inferior alveolar artery (IAA) within the mandibular canal and in relation to the substructures of the neurovascular mandibular bundle has been sparsely described to date. More detailed information on the exact IAA position would be beneficial for both dental and maxillofacial surgical procedures to minimize complications such as bleeding, nerve compression hematoma, and sensory deficiency.

MATERIAL AND METHODS

In 31 Thiel-preserved and fresh-frozen cadaver hemimandibles the position of the IAA in relation to the structures of the inferior alveolar neurovascular bundle and the mandible borders was analyzed anatomically and histologically.

RESULTS

In 77.4% of the cases, rotation of the IAA around the mental nerve was apparent, resulting in a typical site-dependent IAA position. While the IAA was situated buccally within the pterygomandibular space, buccal-inferior in the mandibular foramen, superior in the molar region, and lingually in the premolar region. In 12.9% of the cases, a persistent lingual position of the IAA was observed for the entire mandibular canal. In one case, an additional mandibular canal and an accessory IAA were identified.

DISCUSSION

This study provides new and encompassing information on the complete course and position of the IAA. This course is of practical use for oral implantology and various surgical procedures in dental- and maxillofacial surgery. Variations in the typical IAA course and site-dependent positional changes may be referred to as mandible growth and functional adaption to occlusion anomalies. This report helps enhance the morphological and functional understanding of IAA relationship during mandible development.

Prevalence of bifid and trifid mandibular canals with unusual patterns of nerve branching using cone beam computed tomography

Lack of knowledge concerning the inferior alveolar canal anatomical variations had proven to increase the incidence of surgical complications, so the study aimed to assess the configuration and prevalence of bifid and trifid mandibular canals using cone beam CT in Egyptian subpopulation. Cone beam CT scans of 278 patients (530 hemi-mandibles) were included in the study, in which bifid and trifid mandibular canals or any other branching patterns were recorded and evaluated. Bifid canals were categorized following Naitoh classification, and the diameter of the main mandibular and accessory canals was measured. Bifid canals were detected in 181 canals (34%) while trifid canals in 46 canals (8.7%). Upon classifying the bifid canals, 78 canals showed forward type, 40 retromolar type, 33 dental type, and 7 canals showed buccolingual type. Two special bifid canals subtypes were reported in 23 canals and nine distinct patterns of trifid canals were reported in our study. In addition, unusual patterns of canal branching were reported in 5 cases. The mean diameter of the accessory canals was 1.18 ± .54 mm and the main canal was 3.98 ± 1.31 mm. This study reported a high prevalence (54%) of canal branching, which reinforces the importance of cone beam CT in pre-surgical planning.

Inferior alveolar nerve injury following dental implant placement: A medicolegal analysis of French liability lawsuits

AIMS

This study thus aimed to review and analyze liability lawsuits resulting from implant surgery-related inferior alveolar nerve (IAN) injury over a twenty-year period in France.

MATERIALS AND METHODS

A retrospective descriptive study was performed to analyze judicial decisions pertaining to IAN injury from a legal database between 2000 and 2020. Inclusion criteria comprised all closed malpractice cases that involved an oral and maxillofacial surgeon or a dentist who performed a mandibular implant surgery resulting in IAN injury. The following data were recorded: judicial decision reference (including jurisdiction and date of final court ruling), timing between the incident and final court ruling, number of involved practitioners, patient's age and gender, practitioner's age and gender, implant type, number of implants, location of iatrogenic implant(s), allegation of IAN injury, alleged cause of injury, justification(s) for conviction, compensation amount and legal costs.

RESULTS

Twelve judicial decisions from high civil courts relating to ten closed cases of liability lawsuits were included and analyzed. All of involved practitioners were dentists or oral surgeons, working in the private sector. Eventually, 85% of them were convicted. Mean indemnification was 17,340€ and highest indemnification was 42,828€ (inflation-adjusted in 2020 euros). Mean interval between the incident and final ruling was 87,1 ± 34,2 months.

CONCLUSIONS

Permanent nerve injury following dental implant placement can result in legal action. In the event of lawsuit, the risk of being convicted is high. Practitioners performing oral implantology procedures should practice effective risk management to avoid time-consuming unwanted litigations and administrative proceedings.

Anatomical Variation in the Mandibular Foramen in Non-Atrophic and Atrophic Mandibles

Objectives

Previous studies of variation in mandibular foramen characteristics with age have involved comparison in different populations, but few data, between non-atrophic and atrophic mandibles are available. The aim of this original article was to compare the position, shape and area of the mandibular foramen between non-atrophic and atrophic mandibles.

Material and Methods

Morphometric methods were used to study the mandibular foramen variation. Fifty adult dry mandibles from the laboratory of anatomy were selected. Mandibles were considered non-atrophic if the distance between the base and alveolar ridge was homogeneous and greater than 25 mm in the anterior region and 20 mm in the posterior region. Conversely, mandibles were considered atrophic if that distances were lower than those described to a minimum of 11 mm in all areas. All measurements were performed with a digital caliper. For statistical analysis, the admitted level of significance was 5%.

Results

When non-atrophic mandibles were compared to atrophic ones, the mandibular foramen shifted significantly to an anterior position (mean difference [MD]: 4.81 mm; P < 0.0001) and to an inferior position (MD: 3.04 mm; P < 0.0001) and changed from an elliptical shape to round one, with a significant decrease in its area (MD: 3.66 mm²; P < 0.05).

Conclusions

The results indicate that there are significant differences in the position, shape and area of the mandibular foramen between non-atrophic and atrophic mandibles. These data should be considered in anaesthetic techniques and surgical procedures to prevent vascular and nervous lesions.

Computed Tomography for the Assessment of the Potential Risk After Implant Placement in Fresh Extraction Sites in the Posterior Mandible

Immediate implant placement (IIP) is considered a reliable procedure, with survival rates of 94.9%-98.4%. Nevertheless, in the posterior mandible, it poses a high risk of damage to anatomic structures. The aim of this study was to determine the risk of anatomic structures injury associated with IIP in the posterior mandible based on apical primary stability, respecting a safe distance from the inferior alveolar nerve and lingual plate, and to evaluate the influence of different factors on those risks. Pre-extraction cone beam computed tomography scans of 100 patients were retrospectively analyzed. Measurements were taken from tooth apices to lingual plate and to mandibular canal. Values of <4 mm of the former and <6 mm of the latter were categorized as considerable risk. Values of <2 mm at both measurements were considered high risk. Two-sided P < .05 was considered statistically significant. Mean root-to-alveolar canal distance was 7.6 ± 2.7 mm in the first molar, 6.5 ± 3mm in the second premolar, and 5.4 ± 3 mm in the second molar (P < .005). The mean distance to the outer lingual cortex was 3.9 ± 2.1 mm in the first molar and 3.2 ± 0.1 mm in the second molar. Thus, second molars were at higher risk of inferior alveolar nerve injury and lingual plate perforation during IIP. Background factors associated with higher IIP risk were female sex and age < 40 years. In the mandible, the anatomic risk posed by IIP is greatest for second molars and lowest for first molars. Several background factors affect the distances between root apices and the mandibular canal.

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.

Positioning errors of dental implants and their associations with adjacent structures and anatomical variations: A CBCT-based study

Purpose

The objective of the present study was to evaluate the prevalence of dental implants positioning errors and their associations with adjacent structures and anatomical variations by means of cone-beam computed tomography (CBCT).

Materials and Methods

CBCT images of 207 patients (584 dental implants) were evaluated by 2 oral radiologists. The distance between the implant and the adjacent teeth/implants was measured and classified as adequate (≥1.5 mm and ≥3 mm, respectively) or inadequate. The presence of thread exposure, cortical perforation, implant dehiscence, implant penetration into adjacent structures, and anatomical variations was also recorded. The incisor canal diameter and the depth of the concavity of the submandibular fossa were measured in order to evaluate their correlations with the frequency of implant penetration in these structures. Descriptive analyses, the Fisher exact test, and Spearman correlation analysis were performed (α=0.05).

Results

The overall prevalence of positioning errors was 82.9%. The most common error was the inadequate distance between the implant and the adjacent teeth/implants. The presence of anatomical variations did not significantly influence the overall prevalence of errors (P>0.05). There was a positive correlation between the diameter of the incisor canal and the frequency of implant penetration in this structure (r=0.232, P<0.05).

Conclusion

There was a high prevalence of dental implant positioning errors, and positioning errors were not associated with the presence of anatomical variations. Professionals should be aware of the space available for implant placement during the preoperative planning stage.

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.

UC-USP collaborative exercise on photobiomodulation therapy in neurological orofacial disturbances

Background

Neurosensory peripheral disorders are one of the most common risks associated with iatrogenic and/or post-traumatic injuries. It is often related to disability. Photobiomodulation therapy (PBMT) is a nonsurgical and safe procedure which can accelerate and improve the regeneration of injured biological tissue. This study aims to analyze the impact of PBMT, in the quality of life and impairment of individuals with orofacial neurological peripheral disturbance.

Material and Methods

A retrospective analysis in the database of the dental traumatology clinic of the Hospital Centre of the University of Coimbra/Faculty of Medicine of the University of Coimbra was performed.5 out of 50 individuals were selected, according to the selection criteria. The neurosensory activity was assessed by a pinprick nociceptive test and the EQ-5D-5L self-report questionnaire was used to analyse the quality of life. The study was performed in two phases:1) inactive laser or placebo phase, for one month and 2) active laser or treatment phase. A diode low-level laser device (SIROLaserBlue;Sirona,Germany) was used, according to our protocol. A collaborative protocol in the PBMT influence in individuals with neurosensory peripheral disturbances was studied.

Results

There was no improvement in the neurosensory activity nor in the quality of life, in the placebo phase. After the treatment phase, the EQ-5D-5L final results reported no problems in all of the five dimensions, except for anxiety/depression in individuals with long-standing neurosensory peripheral disturbances. The EQ-VAS scores increased in all the individuals.

Conclusions

Our results supported the improvement of quality of life and impairment reduction in the individuals submitted to PBMT.

Key words:Low-level light therapy, peripheral nerve injuries, sensation disorders, quality of life, forensic medicine.

Biomechanical comparison of implantation approaches for the treatment of mandibular total edentulism

Applying four anterior implants placed vertically or tilted in the mandible is considered to provide clinically reasonable results in the treatment of mandibular posterior edentulism. It is also reported that a combination of four anterior and two short posterior implants can be an alternative approach for the rehabilitation of severe atrophy cases. In this study, we aimed to evaluate the biomechanical responses of three different implant placement configurations, which represent the clinical options for the treatment of mandibular edentulism. Three-dimensional models of the mandible, prosthetic bar, dental implant, abutment, and screw were created. Finite element models of the three implant configurations (Protocol 1: Four anterior implants, Protocol 2: Four anterior and two short posterior implants, Protocol 3: Two anterior and two tilted posterior implants: All-on-4™ concept) were generated for 10 patients and analyzed under different loading conditions including chewing, biting, and impact forces. Protocol 2 led to the lowest stress concentrations over the mandible among the three protocols (p < 0.016). Protocol 2 resulted in significantly lower stresses than Protocol 3 and Protocol 1 over prosthetic bars under chewing forces (p < 0.016). None of the implant placement protocols consistently exhibited the lowest stress distribution over abutments. The lowest stresses over dental implants under the chewing, biting, and impact forces were obtained in Protocol 1, Protocol 2, and Protocol 3, respectively (p < 0.016). Protocol 3 was the best option to obtain the lowest stress values over the screws under all types of loading conditions (p < 0.016). In conclusion, Protocol 2 was biomechanically more ideal than Protocol 1 and Protocol 3 to manage the posterior edentulism.

A CBCT Based Three-Dimensional Assessment of Mandibular Posterior Region for Evaluating the Possibility of Bypassing the Inferior Alveolar Nerve While Placing Dental Implants

A high rate of nerve injury and related consequences are seen during implant placement in the posterior mandibular arch. An approach has been proposed to avoid nerve injury by dodging the inferior alveolar nerve (IAN) while placing an implant. A prospective study with a total of 240 CBCT (cone beam computed tomography) images of patients with three dentate statuses, namely, edentulous (group I), partially edentulous (group II) and dentate (group III) were included in the study. The nerve path tracing was done on CBCT images with On-demand 3D software. The three dimensions, i.e., the linear distance from the outer buccal cortical plate to the inferior alveolar nerve (BCPN), linear distance from the outer lingual cortical plate to the inferior alveolar nerve (LCPN) and linear distance from the midpoint of the alveolar crest to the inferior alveolar nerve (ACN) were assessed. The data were presented and analyzed between variables using one-way ANOVA and independent t-test in SPSS version 21.LCPN of the right 1st premolar region (p < 0.05) was significantly different among the groups with edentulous subjects recorded with the minimum value (6.50 ± 1.20 mm). Females were found to have significantly (p < 0.05) less available bone (6.03 ± 1.46 mm) on the right side of the mandibular jaw compared to males in edentulous group of patients. On comparing age groups for partially edentulous subjects, LCPN of the right 1st premolar region had significantly (p < 0.05) less available bone (6.03 ± 0.38 mm) in subjects with age ≥54 years. The IAN follows a lingual course in the molar region and later flips to the buccal side in the premolar region. The LCPN dimension in the 1st and 2nd premolar region was found to be more than 6 mm irrespective of age, gender and side of the jaw. Thus, it can be considered as a suitable site for placing implants while bypassing the IAN with CBCT assessment remaining as the mainstay in the pre-surgical phase.

Diagnostic Potential of Panoramic Radiography and CBCT in Detecting Implant-Related Ex Vivo Injuries of the Inferior Alveolar Canal Border

The aim of this ex vivo study was to compare the diagnostic performances of panoramic radiography and cone beam computerized tomography (CBCT) in detecting implant-related injuries of the inferior alveolar canal. Monocortical bone windows were created in 60 fresh sheep hemimandibles, the inferior alveolar canals were revealed and 120 dental implants were inserted. Three types of injuries, described as pilot drill damage (PDRILL), collapsing of the superior border of the canal (COLL), penetration of the implant tip into the canal (PENET) and one control group, were simulated. Standard (PANO) and dentition mode panoramic (PANO-DENT) images as well as CBCT data presented as multiplanar reconstruction (MPR) and cross-sectional (CROSS) views were evaluated by 6 observers who had also expressed their level of confidence to their final diagnosis. Intra- and interobserver agreement scores were rated good. The area under the curve (AUC) values and the confidence scores for CROSS and multiplanar reformation (MPR) views were both significantly higher than those of PANO and PANO-DENT (P < .05 for each) in PDRILL group. In COLL group, observers showed less confidence to PANO and PANO-DENT compared to CROSS and MPR techniques (P < .05 for each). No other significant differences were found. Within the limits of this experimental study, it can be suggested that the standard and dentition modes of panoramic radiography can be as effective as CBCT in the detection of penetrating and collapsing injuries, but multiplanar and cross-sectional views of the CBCT are more accurate than panoramic radiography in the detection of pilot drill injuries in sheep mandible.

How Successful is Supplemental Intraseptal and Buccal Infiltration Anaesthesia in the Mandibular Molars of Patients Undergoing Root Canal Treatment or Tooth Extraction?

Objectives

To investigate the success rate of supplemental intraseptal and buccal infiltration anaesthesia in mandibular molars undergoing endodontic therapy/extraction when the inferior alveolar nerve block has failed.

Material and Methods

A prospective clinical trial including 200 patients undergoing lower molar root canal treatment/teeth extraction was conducted. Only 80 patients of the participants who had profound lower lip anaesthesia after the administration of inferior alveolar nerve block (IANB) were in pain within treatment. Patients experiencing moderate to severe pain upon using elevators, forceps, bur, or endodontic file were randomly allocated to the 2% lidocaine intraseptal injection and 4% articaine buccal infiltration groups. Level of pain was assessed every 2 to 10 min on standard 100 mm visual analogue scales.

Results

Overall, 55 (69%) of patients who were given either intraseptal injection of 2% lidocaine or buccal infiltration of 4% articaine had successful anaesthesia of lower molar teeth within 10 min. However, 25 (31%) of participating patients in the buccal infiltration and the intraseptal groups had failed anaesthesia within the study duration (10 min), and they received additional local anaesthetic. IANBs were more painful than buccal and intraseptal injections. However, buccal articaine injections were significantly more comfortable than intraseptal lidocaine injections (P > 0.001).

Conclusions

Supplemental intraseptal injection of 2% lidocaine and buccal infiltration of 4% articaine achieved profound pulpal anaesthesia in 69% of patients when the inferior alveolar nerve block failed. Recommendations can be given to dental practitioners to use infiltration of 4% articaine in conjunction with intraseptal injection of 2% lidocaine to anaesthetize the lower molar teeth when inferior alveolar nerve block fails.

Anatomical study: the potential movability of the inferior alveolar nerve

OBJECTIVE

Nerve repair and repositioning are procedures for treating and avoiding injury to the inferior alveolar nerve during oral and maxillofacial surgery. The present study aimed to examine how the mobility of the inferior alveolar neurovascular bundle (IAB) changes with or without removing the bone around the mental foramen (MF).

STUDY DESIGN

Six fresh-frozen cadavers (11 sides) were dissected in this study. Osteotomy in the buccal cortical bone was performed from 5 mm posterior to the MF to the distal edge of the second molar with a high-speed drill and osteotome. Next, the distance from the lateral surface of the buccal cortical bone to the retracted IAB was measured with and without removing the bone around the MF.

RESULTS

The distance from the lateral surface of the buccal cortical bone to the retracted IAB without removing the bone around the MF was 0 mm on all sides. After removing the bone, the mean distance changed by 4.71 ± 1.41 mm (range 2.83-7.90). There was no statistically significant difference between the right and left sides.

CONCLUSIONS

The results of this study support removing the bone around the MF for increased mobility of the IAB.

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.

Gauging electrical properties of bone with a bioimpedance-sensing drill

OBJECTIVE

Multiple surgical procedures require drilling through bone to access underlying anatomy or for device placement. In dental applications, iatrogenic injury caused by accidental perforation of cortical bone into critical anatomy occurs in a significant number of dental implant procedures. Limited real-time sensing methods are available to guide clinicians while drilling through cancellous bone towards cortical interfaces. Early interface detection could prevent accidental damage to underlying anatomic structures. This study aims to demonstrate that electrical impedance spectroscopy can be integrated within a standard surgical drill to distinguish between bone types.

APPROACH

A custom bearing and insulated drill bit were designed to collect 10 cortical and cancellous impedance measurements from ex vivo femurs (2 pigs) and 80 bone measurements from in situ femurs (4 pigs). In the in situ study, two return electrodes (simulating a lip-clip and shoulder pad) were used to assess impedance differences associated with return electrode geometry.

MAIN RESULTS

Significant ex vivo differences (p  <  0.05) between cortical and cancellous bone occurred in the real resistivity from 0.1 to 100 kHz and in the imaginary resistivity from 0.3 to 10 kHz, with a maximum cortical-to-cancellous impedance ratio of 1.48. Significant in situ differences (p  <  0.01) were observed in both real and imaginary resistivities from 0.1 to 100 kHz, with a maximum impedance ratio of 2.94. AUCs for classifying bone type based on the real resistivity ranged from 0.84 to 0.96 for ex vivo bone and 0.98 to 1.0 for in situ bone. Mean differences between return electrode geometries were less than 5%.

SIGNIFICANCE

The significant cortical-to-cancellous contrast observed indicates this system's potential to provide real-time tissue differentiation during bone drilling procedures.

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.