Assessment of traumatic mandibular nerve using MR neurography sequence: a preliminary study.

BACKGROUND: Iatrogenic mandibular nerve damage resulting from oral surgeries and dental procedures is painful and a formidable challenge for patients and oral surgeons alike, mainly because the absence of objective and quantitative methods for diagnosing nerve damage renders treatment and compensation ambiguous while often leading to medico-legal disputes. The aim of this study was to examine discriminating factors of traumatic mandibular nerve within a specific magnetic resonance imaging (MRI) protocol and to suggest tangible diagnostic criteria for peripheral trigeminal nerve injury. METHODS: Twenty-six patients with ipsilateral mandibular nerve trauma underwent T2 Flex water, 3D short tau inversion recovery (STIR), and diffusion-weighted imaging (DWI) acquired by periodically rotating overlapping parallel lines with enhanced reconstruction (PROPELLER) pulse sequences; 26 injured nerves were thus compared with contra-lateral healthy nerves at anatomically corresponding sites. T2 Flex apparent signal to noise ratio (FSNR), T2 Flex apparent nerve-muscle contrast to noise ratio (FNMCNR) 3D STIR apparent signal to noise ratio (SSNR), 3D STIR apparent nerve-muscle contrast to noise ratio (SNMCNR), apparent diffusion coefficient (ADC) and area of cross-sectional nerve (Area) were evaluated. RESULTS: Mixed model analysis revealed FSNR and FNMCNR to be the dual discriminators for traumatized mandibular nerve (p < 0.05). Diagnostic performance of both parameters was also determined with area under the receiver operating characteristic curve (AUC for FSNR = 0.712; 95% confidence interval [CI]: 0.5660, 0.8571 / AUC for FNMCNR = 0.7056; 95% confidence interval [CI]: 1.011, 1.112). CONCLUSIONS: An increase in FSNR and FNMCNR within our MRI sequence seems to be accurate indicators of the presence of traumatic nerve. This prospective study may serve as a foundation for sophisticated model diagnosing trigeminal nerve trauma within large patient cohorts.

Risk assessment of inferior alveolar nerve injury after wisdom tooth removal using 3D AI-driven models: A within-patient study.

OBJECTIVE: To compare a three-dimensional (3D) artificial intelligence (AI)- driven model with panoramic radiography (PANO) and cone-beam computed tomography (CBCT) in assessing the risk of inferior alveolar nerve (IAN) injury after mandibular wisdom tooth (M3M) removal through a within-patient controlled trial. METHODS: From a database of 6,010 patients undergoing M3M surgery, 25 patients met the inclusion criteria of bilateral M3M removal with postoperative unilateral IAN injury. In this within-patient controlled trial, preoperative PANO and CBCT images were available, while 3D-AI models of the mandibular canal and teeth were generated from the CBCT images using the Virtual Patient Creator AI platform (Relu BV, Leuven, Belgium). Five examiners, who were blinded to surgical outcomes, assessed the imaging modalities and assigned scores indicating the risk level of IAN injury (high, medium, or low risk). Sensitivity, specificity, and area under receiver operating curve (AUC) for IAN risk assessment were calculated for each imaging modality. RESULTS: For IAN injury risk assessment after M3M removal, sensitivity was 0.87 for 3D-AI, 0.89 for CBCT versus 0.73 for PANO. Furthermore, the AUC and specificity values were 0.63 and 0.39 for 3D-AI, 0.58 and 0.28 for CBCT, and 0.57 and 0.41 for PANO, respectively. There was no statistically significant difference (p>0.05) among the imaging modalities for any diagnostic parameters. CONCLUSION: This within-patient controlled trial study revealed that risk assessment for IAN injury after M3M removal was rather similar for 3D-AI, PANO, and CBCT, with a sensitivity for injury prediction reaching up to 0.87 for 3D-AI and 0.89 for CBCT. CLINICAL SIGNIFICANCE: This within-patient trial is pioneering in exploring the application of 3D AI-driven models for assessing IAN injury risk after M3M removal. The present results indicate that AI-powered 3D models based on CBCT might facilitate IAN risk assessment of M3M removal.

Healthcare costs of post-traumatic trigeminal neuropathy in Belgium - A retrospective analysis.

The present aim was to estimate direct health care costs of patients suffering from post-traumatic trigeminal neuropathy (PTTN) and to compare the use of health care services, medications, and costs between temporary and persistent (>3 months) PTTN cohorts. A pre-existing clinical dataset of PTTN patients visiting a tertiary orofacial pain clinic in Belgium was utilized, including symptoms and quality of life measurements. Cost and resource utilization data were obtained by Belgium's largest health insurance provider for a period of 5 years after onset. Data from 158 patients was analyzed. The average cost per patient in the first year after injury was €2353 (IQR 1426-4499) with an out-of-pocket expense of 25% of the total cost. Hospitalization and technical interventions were the main drivers of cumulative costs, followed by consultation costs. For each cost category, expenditure was significantly higher in patients with persistent PTTN than in those with temporary PTTN (median 5-year total costs in persistent PTTN patients yielded €8866 (IQR 4368-18191) versus €4432 (IQR 2156-9032) in temporary PTTN, p <0.001) PTTN patients received repeated and frequent head and neck imaging (mean number of imaging investigations per patient was 10 ± 12). Medication consumption was high, with an unwarranted higher use of opioids and antibiotics in persistent PTTN patients. Within the limitations of this study, it seems there is a need for informing patients in detail on the inherent risks of nerve damage during dental and oromaxillofacial procedures. Every surgery should be preceded by a risk-benefit assessment in order to avoid unnecessary nerve damage.

Novel strategy to predict high risk of inferior alveolar nerve injury during extraction of lower third molars based on assessment of computed tomographic images of multiple anatomical features.

Preoperative assessment is essential to prevent inferior alveolar nerve (IAN) injury during surgical extraction of the lower third molar (LM3). Here, we aimed to establish an assessment system to predict IAN injury during surgical extraction of the LM3. We conducted a retrospective cohort study on 115 patients diagnosed as 'high-risk' based on our previous risk assessment method involving three anatomical features of the inferior alveolar canal using computed tomographic (CT) images. We evaluated the occurrence of neurosensory impairment in these high-risk patients, and its association with novel anatomic features based on CT images. Neurosensory impairments were observed in 19 patients (16.5%). The inferior alveolar canal major diameter (p < 0.0001) and lingual bone thickness (p = 0.0039) were significantly associated with the occurrence of neurosensory impairment during LM3 extraction. Receiver operating characteristic curves were used to determine cut-off values of these quantitative factors to specifically predict IAN injury. Preoperative risk assessment with quantitative factors based on anatomical features observed on CT images may facilitate more appropriate surgical planning for patients at a high risk of IAN injury.

The Assessment of Neurosensory Disturbance Following Bilateral Sagittal Split Osteotomy With Subjective and Three-Dimensional Evaluation.

PURPOSE: Inferior alveolar neurosensory disturbance (IAND) is the most common complication of bilateral sagittal split osteotomy (BSSO). The aim of the present study was to evaluate IAND with subjective tests postoperatively and assess the relationship between three-dimensional measurements of the mandibular canal (MC) and IAND. METHODS: Eighteen patients (Mean age: 24.05 ±â€Š5.85 years) treated with BSSO were retrieved from the archive. Subjective tests (light touch, tactile sensitivity, 2-point discrimination, brush-stroke directional discrimination, sharp/blunt discrimination, dental vitality, questionnaire) and three-dimensional measurements related to MC and fixation screws were done postoperatively (on average 20.43 ±â€Š8.76 months after surgery). Statistical significance was set at P  < 0.05. RESULTS: Subjective test results were found compatible with each other except brush-stroke directional discrimination test. According to the questionnaire, IAND was apparent in all patients immediately after surgery, and recovery after 1 to 2 years was statistically significant ( P  < 0.05). Preoperative ramus width, medial and lateral cancellous bone lengths, the decrease in MC length, and the presence of screw in MC were not related to IAND ( P  < 0.05). CONCLUSIONS: There is a high incidence of IAND following BSSO, and the subjective tests are efficient to evaluate the disturbance. Spontaneous recovery of the nerve occurs during the follow-up periods. Instead of preoperative measurements of bone thickness, MC length, and the position of fixation screws, the surgical procedure seems to be more important in IAND occurrence.

A systematic review on diagnostic test accuracy of magnetic resonance neurography versus clinical neurosensory assessment for post-traumatic trigeminal neuropathy in patients reporting neurosensory disturbance.

OBJECTIVES: To perform a systematic review of published studies on diagnostic accuracy of magnetic resonance neurography (MRN) vs clinical neurosensory testing (NST) for post-traumatic trigeminal neuropathy (PTTN) in patients reporting neurosensory disturbances (NSD). METHODS: Human studies except case reports, reviews, systematic reviews and meta-analyses were included. PubMed, Embase, Web of Science and Cochrane Library were consulted. Risk of bias assessment was conducted using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. Predetermined data extraction parameters were noted and summarized. RESULTS: 8 studies met eligibility criteria of which 7 were retrospective, representing 444 subjects. Most studies were at high risk of bias with low applicability concerns. Populations and objectives were divergent with a large variation in timing (3 days-17 years post injury) and parameters (multiple coil designs, fat suppression techniques, additional contrast agent) of MRI acquisition. T2 weighted 3 T imaging with short echo times (2.2-100 ms) and fat suppression was applied in seven studies, techniques varied. Determination of sensitivity and specificity could not be performed due to the methodological variation between studies and lacking comparative data between index and reference tests. Based on limited data, PTTN correlated reasonably well between clinical assessment, intraoperative findings and MRN abnormalities (k = 0.57). Increased signal intensity correlated with persistency of neurosensory disturbances in one study. Intra- (ICC 0.914-0.927) and interobserver (k = 0.70-0.891) MRN variability was considered good to excellent. One retrospective study showed substantial impact of MRN on clinical decision making in one-third of patients. CONCLUSION: Currently, there is insufficient scientific knowledge to support or refute the use of MRN. Based on limited data, MRN seems promising and reliable in detection and grading of PTTN. Methodological issues underline the importance for prospective blinded studies with standardization of signal intensity calculation and rigorous reporting of MRI acquisition parameters.

A systematic review of the complications of high-risk third molar removal and coronectomy: development of a decision tree model and preliminary health economic analysis to assist in treatment planning.

Coronectomy is an alternative surgical technique for the management of high-risk third molars. It involves the removal of the crown of a tooth and the deliberate retention of the roots, thereby avoiding injury to the inferior alveolar nerve (IAN). Previous studies have suggested that it reduces the risk of nerve injury when compared with surgical extraction. The purpose of this study was to systematically review the incidence of complications following coronectomy such as IAN injury, pain, dry socket, infection, root migration, and need for re-operation. A comparative cost analysis of coronectomy and surgical extraction was done based on the results of the review. This provides an insight into the economic implications of the two procedures. A search through the MEDLINE database via Ovid, PubMed, Scopus, EMBASE via Ovid, and Web of Science, was carried out to extract randomised and non-randomised controlled trials. Four studies fulfilled the inclusion criteria. A meta-analysis was conducted to measure the overall effect of each outcome. The pooled odds ratio (OR) for IAN injury was 0.16 (95% CI 0.01 to 0.39). Coronectomy reduced this risk by 84%. Dry socket may occur less frequently following coronectomy whereas infection did not show a higher incidence with either intervention. Root migration was found to occur in 13%-85% of cases and the average incidence of re-operation was 2.2%. The ratio of the average costs was 1.12 favouring coronectomy if cone-beam computed tomography (CBCT) was not done prior to the procedure. If a scan was taken routinely for coronectomy, the cost ratio marginally favoured extraction. Coronectomy reduced the risk of nerve injury in high-risk third molars. Definitive conclusions, however, cannot be made for outcomes such as the need for re-operation, which may alter the cost ratio of coronectomy:extraction, as higher quality studies with longer follow-up are needed.

High resolution MRI for quantitative assessment of inferior alveolar nerve impairment in course of mandible fractures: an imaging feasibility study.

The purpose of this study was to evaluate a magnetic resonance imaging (MRI) protocol for direct visualization of the inferior alveolar nerve in the setting of mandibular fractures. Fifteen patients suffering from unilateral mandible fractures involving the inferior alveolar nerve (15 affected IAN and 15 unaffected IAN from contralateral side) were examined on a 3 T scanner (Elition, Philips Healthcare, Best, the Netherlands) and compared with 15 healthy volunteers (30 IAN in total). The sequence protocol consisted of a 3D STIR, 3D DESS and 3D T1 FFE sequence. Apparent nerve-muscle contrast-to-noise ratio (aNMCNR), apparent signal-to-noise ratio (aSNR), nerve diameter and fracture dislocation were evaluated by two radiologists and correlated with nerve impairment. Furthermore, dislocation as depicted by MRI was compared to computed tomography (CT) images. Patients with clinically evident nerve impairment showed a significant increase of aNMCNR, aSNR and nerve diameter compared to healthy controls and to the contralateral side (p < 0.05). Furthermore, the T1 FFE sequence allowed dislocation depiction comparable to CT. This prospective study provides a rapid imaging protocol using the 3D STIR and 3D T1 FFE sequence that can directly assess both mandible fractures and IAN damage. In patients with hypoesthesia following mandibular fractures, increased aNMCNR, aSNR and nerve diameter on MRI imaging may help identify patients with a risk of prolonged or permanent hypoesthesia at an early time.

Assessment of Somatosensory and Psychosocial Function of Patients With Trigeminal Nerve Damage.

OBJECTIVE: The present study assessed somatosensory changes related to trigeminal nerve damage using extensive evaluation tools and assessed the effect of such damage on the patients' psychosocial status and quality of life compared with healthy participants. METHODS: In 37 patients with intraorally or extraorally presenting trigeminal nerve damage diagnosed as painful or nonpainful posttraumatic trigeminal neuropathy, psychophysical tests like quantitative sensory testing (QST) and qualitative sensory testing and the electrophysiological "nociceptive-specific" blink reflex were performed. The patients and 20 healthy participants completed a set of questionnaires assessing their psychosocial status and quality of life. RESULTS: A loss or gain of somatosensory function was seen in at least 1 QST parameter in >88.9% of the patients. Patients in whom extraoral QST was performed showed an overall loss of somatosensory function, whereas intraoral QST showed a general gain of somatosensory function. Qualitative sensory testing identified a side-to-side difference in the tactile and pinprick stimulation in >77% of the patients. An abnormal "nociceptive-specific" blink reflex response was seen in 42.1% to 71.4% of patients dependent on the trigeminal branch stimulated, though comparisons with healthy reference values showed ambiguous results. Compared with the healthy participants, patients showed higher scores for pain catastrophizing, symptoms of depression and anxiety, limited jaw function, more somatic symptoms, and significantly impaired oral health-related quality of life (all P<0.038). DISCUSSION: The results from the present study showed presence of varied somatosensory abnormalities when assessed using psychophysical and electrophysiological investigations and a significantly impaired psychosocial status.

Assessment of the reliability of radiographic signs on panoramic radiographs to determine the relationship between mandibular third molars and the inferior alveolar canal.

OBJECTIVE: To assess the reliability of radiographic signs of the relationship between impacted mandibular third molars (IMTMs) and the inferior alveolar canal (IAC), and the vertical relationship between IMTM and IAC on panoramic radiographs (PRs) as risk indicators for IAC exposure during extraction. STUDY DESIGN: Seven radiographic signs regarding the appearance of roots and the IAC were assessed as present or absent on PRs. The vertical relationship between IMTM and the IAC was divided into 3 levels. The correlation between radiographic data and IAC exposure during extraction was analyzed by using χ2 statistics and logistic regression analysis. RESULTS: In total, 198 IMTMs were examined. In 46 cases (23.2%), the IAC was exposed during extraction. Four radiographic signs-darkening of the root, narrowing of the root, narrowing of the IAC, and diversion of the IAC-were associated with IAC exposure (P < .05). Concurrence of 2 or more of 7 radiographic signs increased the risk of IAC exposure (P < .001). The vertical relationship between IMTM and the IAC was found to be a risk indicator for IAC exposure (P < .001). No significant correlation was found between IAC exposure and inferior alveolar nerve damage (P = .148). CONCLUSIONS: Panoramic radiography is useful for assessing the risk of IAC exposure during IMTM extraction.

Assessment of Somatosensory Function, Pain, and Unpleasantness in Two Surrogate Models of Trigeminal Nerve Damage: A Randomized, Double-Blind, Controlled Crossover Study.

AIMS: To assess the pain and/or unpleasantness and the somatosensory changes caused by two experimental models of trigeminal nerve damage (topical application of capsaicin and local anesthetics) in healthy participants using extensive evaluation tools. METHODS: This double-blinded, randomized, placebo-controlled, crossover study included 20 healthy adult participants who underwent three separate sessions of testing. In each session, the psychophysical quantitative sensory testing (QST) and the electrophysiologic electrically evoked trigeminal "nociceptive-specific" blink reflex (nBR) investigations were performed at baseline. Following a 15-minute topical application of 0.1% capsaicin, 5% EMLA, or Vaseline (placebo) agents, the maximum numeric rating scale pain and unpleasantness scores were recorded. Additionally, qualitative sensory testing and somatosensory mapping were performed. The QST and nBR investigations were repeated immediately after each application. Data were analyzed using repeated-measures analysis of variance. RESULTS: Capsaicin application was associated with significantly higher pain and unpleasantness scores when compared to EMLA and Vaseline (P < .001), with varied bidirectional somatosensory changes among the participants and significant loss of thermosensory function (P < .030). EMLA application induced loss of thermal and mechanical somatosensory function (P < .030) and a significant reduction in electrically evoked pain scores on nBR investigation (P < .001). No significant changes were seen in the electrophysiologic component of the nBR after any of the applications (P = .922). CONCLUSION: Topical capsaicin and EMLA application mimicked certain aspects of somatosensory changes seen in trigeminal nerve damage patients and may be used as surrogate models of such changes.

Plain radiographs for the assessment of coronectomy: not always a case of black or white.

In recent years, coronectomy of impacted lower third molar teeth has become an increasingly popular alternative to removal. Traditionally, orthopantomograms of mandibular third molars have been used to indicate features that show that the tooth is in close proximity to, or in an intimate relation with, the inferior dental nerve. Some authors advocate coronectomy as opposed to surgical removal to reduce the risk of damage to the nerve. In our Trust during the last two years, there has been a noticeable increase in the prescription of coronectomy for the management of pericoronitis associated with mandibular third molars. The purpose of this study therefore was to examine the differences among clinicians in their assessment of the need for coronectomy using plain-view radiographs. An online survey was completed by 25 clinicians with different levels of experience from six units across the UK and Republic of Ireland. We found a wide variation in the number of coronectomies prescribed (intraclass correlation 2.67), and when prescribed, a lack of agreement about the radiographic feature that had influenced the decision. These judgments are not straightforward. They are, to some extent, subjective, and in certain cases may benefit from a team-led approach.

[A PhD completed. Pre-surgical assessment of the mandibular body and canal using CBCT imaging.] / Serie: Hora est. Prechirurgisch onderzoek van mandibula en canalis mandibularis met CBCT-scans.

The aim of this study was to determine the accuracy of the pre-surgical assessment of the mandible using cone beam computed tomography (CBCT) images. For surgical procedures in the mandible, it is important to determine the position of the mandibular canal in order to avoid damage to the inferior alveolar nerve (IAN). The best method to investigate this nerve is with the help of panoramic reconstructed images combined with cross-sectional reconstructed images. To protect the IAN during treatment, this research indicates that a minimal safety zone of 1.13 mm is advisable. When distances were being measured, a larger exaggeration of reality was observed with small distances. It appears that (semi)automatic tracing methods of the mandibular canal still cannot be used in clinical practice. When a CBCT scan reveals a lingual position of the mandibular canal in combination with a narrowing of the mandibular canal at the contact point with the root of a third molar the risk of damaging the IAN increases. CBCT imaging should only be applied in specific cases.

A Survey of the Opinion and Experience of UK Dentists Part 3: An Evidence-Based Protocol of Surgical Risk Management Strategies in the Mandible.

BACKGROUND: Implant surgery in the mandible can cause serious complications that can be life threatening. The incidence and cause of iatrogenic trigeminal nerve injury (TNI) related to dental implant surgery was investigated in a survey of the opinion and experience of the UK dentists and reported by the authors in part 1 of this series of articles. Part 2 reported on the risk assessment and management of implant-related inferior alveolar nerve (IAN), mental nerve (MN), and lingual nerve (LN) injuries. This article evaluates the significance of these findings and recommends an evidence-based protocol of risk management strategies to reduce the risk of TNI related to dental implant surgery. METHODS: A survey was distributed among 405 dentists attending an Association of Dental Implantology (ADI) congress, of which 187 completed the survey. RESULTS: In this study, the strategies to manage the risk of TNI included unilateral staging of implant placement (57%) and identification the MN when placing implants (43%). Twelve percent used drill stops when operating in the mandible. Nineteen dentists used steroids (eg, dexamethasone) routinely preoperatively and postoperatively. Twenty-six dentists used basic cone beam computed tomography minimally invasive techniques, and 70% encountered a large anterior loop of the IAN. Most dentists (76%) allowed a 2- to 4-mm safety zone radiologically above the IAN when placing implants, and over half of the responders (56%) used implants that were 10 mm in length. CONCLUSION: Given the elective nature of implant surgery, TNI should be fully avoidable. The evidence suggest that TNI can be minimized with meticulous attention to accurate assessment and surgical planning as well as carrying out the surgery with a high degree of precision. In part 3 of their series of articles, the authors presented an evidence-based protocol that comprises preoperative, intraoperative, and postoperative risk management strategies for dental implant surgical procedures in the mandible.

A Modified Technique of Mandibular Ramus Sagittal Split Osteotomy for Prevention of Inferior Alveolar Nerve Injury: A Prospective Cohort Study and Outcome Assessment.

BACKGROUND: Postoperative functional impairment of the inferior alveolar nerve (IAN) has been a common and well-recognized complication. Our study introduced a modified Obwegeser-Dal Pont bilateral sagittal split osteotomy (BSSO) technique and evaluated the subsequent incidence of postoperative neurosensory disturbance of IAN. METHODS: In this prospective cohort study, 57 patients receiving our modified BSSO during orthognathic surgery were enrolled. The technique contained opening the 2 ramus cortices and inserting the osteotome bypassing the IAN to avoid nerve injury. A 5-point scale self-assessment questionnaire was used to evaluate IAN neurosensory disturbance one week, six months and 12 months postoperatively. Differences between groups were analyzed using χ test for categorical and Wilcoxon signed-rank test for pairwise categorical data. RESULTS: Complete ramus splitting could be achieved in 109 (95.6%) sides. Lower lip or chin neurosensory disturbances presented in 72 (63.2%) sides 1 week postoperatively and gradually reduced to 9 (7.9%), and 4 (3.5%) at postoperative months 6 and 12, respectively. CONCLUSIONS: This BSSO technique could be safely performed with low rates of IAN exposure and injury and a low incidence of persistent neurosensory disturbance in 3.5% of patients 12 months postoperatively.

A Survey of the Opinion and Experience of UK Dentists: Part 2: Risk Assessment Strategies and the Management of Iatrogenic Trigeminal Nerve Injuries Related to Dental Implant Surgery.

BACKGROUND: Dental implant-related iatrogenic injuries are proportionally increasing with dental implant surgery. This study assessed the experience of implant-related trigeminal nerve (TG) injuries among UK dentists. Risk management strategies and management of implant-related inferior alveolar nerve (IAN), mental nerve (MN), and lingual nerve injuries were investigated. METHODS: A survey was distributed among 405 dentists attending an Association of Dental Implantology (ADI) congress, of which 187 completed the survey. RESULTS: Most dentists (76% of 134 responses) allowed a 2 to 4 mm safety zone radiologically above the IAN when placing implants, and over half of the responders (56%) used implants that were 10 mm in length. The most frequent precautionary measure used by 73 (80%) responders was antibiotic coverage routinely to reduce the risk of infection when placing grafts in the posterior mandible. Other precautionary measures included unilateral staging of implant placement (57%), and 43% always identified the MN when placing implants. Nineteen dentists used steroids (eg, dexamethasone) routinely preoperatively and postoperatively. Twenty-six dentists used basic cone-beam CT (CBCT) minimally invasive techniques, and drill stops during implant placement were used by 14 responders. Although it is not highly recommended, steroids were used to manage the neuropathic pain and discomfort experienced by patients with IAN injuries in 40% of cases. CONCLUSION: Further training of dentists undertaking implant surgery is required so that they acquire up-to-date and evidence-based knowledge and skills in the prevention, diagnosis, and management of dental implant-related TG injuries. This training should also involve the justification and interpretation of CBCTs.

Malpractice claims related to tooth extractions.

OBJECTIVE: The aim of this study was to analyze malpractice claims related to tooth extractions in order to identify areas requiring emphasis and eventually to reduce the number of complications. MATERIAL AND METHODS: We compiled a file of all malpractice claims related to tooth extractions (EBA code) between 1997 and 2010 from the Finnish Patient Insurance Centre. We then examined the data with respect to date, tooth, surgery, injury diagnosis, and the authority's decision on the case. RESULTS: The material consisted of 852 completed patient cases. Most of the teeth were third molars (66 %), followed by first molars (8 %), and second molars (7 %). The majority of claims were related to operative extraction (71 %) followed by ordinary extraction (17 %) and apicoectomy of a single-rooted tooth (7 %) or multi-rooted tooth (2 %). The most common diagnosis was injury of the lingual or inferior alveolar nerve. According to the authority's decision, the patient received compensation more often in cases involving a third molar than other teeth (56 vs. 46 %, P < 0.05). CONCLUSION: The removal of a mandibular third molar was the basis for the majority of malpractice claims. CLINICAL RELEVANCE: To reduce the numbers of lingual and inferior alveolar nerve injuries, the removal of mandibular third molars necessitates recent and high-quality panoramic radiograph, preoperative assessment of the difficulty of removal, and consciousness of the variable anatomical course of the lingual nerve.

Anterior loop of the mental nerve, mental foramen and incisive nerve emergency: tridimensional assessment and surgical applications.

PURPOSE: The aim of this study was to investigate the prevalence and length of the anterior loop (AL), the distance from this landmark to the alveolar crest and its relation with the shape of the foramen and emergency pattern in the Spanish population on helical computed tomography scan (helical CT scan) through tridimensional reconstructions. METHODS: Helical CT scan images of 41 patients aged 65 or older were analyzed. A total of 82 human hemi-mandibles were examined in this study. A tridimensional reconstruction of each mandible and Inferior Alveolar Nerve canal was created in AMIRA® software (AMIRA, Mercury Computer Systems, Berlin, Germany). Prevalence, length and distance between the AL, mental foramen and alveolar ridge were measured. This retrospective observational study was performed according to the STROBE guidelines. RESULTS: Prevalence of the AL was 53.7 % (n = 44) and the mean length was 1.3 ± 0.64 mm. The mean distance from the highest point of the loop to the alveolar ridge was 13.4 ± 2.8 mm. The mean diameter of the mental foramen was 3.5 ± 0.65 mm and the proportion of the oval-shaped was 62.2 % (n = 51) and round-shaped was 37.8 % (n = 31). The study found that patients with type 1 pattern emergency pattern had a higher prevalence of the AL (p = 0.03). CONCLUSIONS: Prevalence, location and length of the anterior loop can be overlooked if only two-dimensional pre-surgical studies are performed. Therefore, three-dimensional imaging and modeling of anatomic structures should be used for the pre-operative examination of the interforaminal area. Given the wide variability of the emergency pattern of the mental nerve and the prevalence and location of the anterior loop, it should be studied in every patient individually.

Cone beam computed tomography in pre-surgical assessment of mandibular third molars.

DesignMulticentre, randomised controlled clinical trial.InterventionPatients referred for third molar removal received a digital panoramic radiograph(PR). Adults with one or more lower third molars in a close relationship with the mandibular canal were eligible for the study. Patients randomised to the cone beam computed tomography (CBCT) group received a high resolution CBCT scan in addition to the PR. All lower third molar extractions were performed under local anaesthesia without sedation and without antibiotic prophylaxis. Information on variables such as experience of the surgeon, duration of surgery and technique for third molar removal were recorded.Outcome measureThe primary outcome measure was the number of patient-reported altered sensations one week after surgery. Secondary outcomes included the number of patients with an objective IAN injury; permanent IAN injury (>6 months); occurrence of other postoperative complications (wound infection, alveolar osteitis); Oral Health Related Quality of Life-14, questionnaire responses; pain (VAS score); duration of surgery; number of emergency visits; and number of missed days of work or study.ResultsThree hundred and forty-one patients with 477 lower third molars were randomised from three centres. Two hundred and sixty-eight patients with 320 mandibular third molars were analysed according to the intention-to-treat principle for the primary and secondary outcomes. The overall incidence of patient-reported altered sensations one week after surgery was 6.3%. At one week there was no difference in subjective IAN injury between the CBCT and PR group. No significant differences were noted between the two groups for any of the secondary outcomes recorded.ConclusionsAlthough CBCT is a valuable diagnostic adjunct for identification of an increased risk for IAN injury, the use of CBCT does not translate into a reduction of IAN injury and other postoperative complications, after removal of the complete mandibular third molar. In these selected cases with a high risk for IAN injury, an alternative strategy, such as monitoring or a coronectomy, might be more appropriate.

An update on the causes, assessment and management of third division sensory trigeminal neuropathies.

Introduction Sensory neuropathies of the mandibular division of the trigeminal (V3) nerve can be debilitating, causing difficulty with daily function. It has a variety of causes, including iatrogenic injury, usually caused by third molar removal, local anaesthetic administration, implant placement or endodontic treatment. Non-iatrogenic causes include infection, primary or secondary neoplasia and various medical conditions.Objective To review the aetiology, evaluation and management of V3 neuropathy in a retrospective case-series of patients referred to a specialist nerve injury clinic over an eight-year period, particularly focusing on the non-iatrogenic causes of this presentation.Methods A retrospective analysis of the case notes of 372 patients referred to the specialist nerve injury clinic between 2006 and 2014 was carried out to establish the cause of the neuropathy and subsequent management or referral. The assessment protocol of trigeminal neuropathy used in the clinic is also outlined.Results Most patients (89.5%) presented with neuropathy due to iatrogenic injury. Of the non-iatrogenic causes (10.5%), malignancy accounted for a fifth of presentations, and infection almost two-fifths, demonstrating the importance of prompt identification of a cause and management by the clinician, or referral to the appropriate specialty. Other, more rare causes are also presented, including multiple sclerosis, sickle-cell anaemia and Paget's disease, highlighting the importance to the clinician of considering differential diagnoses.Conclusions This case series demonstrates the less frequent, but nevertheless important, non-iatrogenic causes which clinicians should consider when assessing patients with trigeminal neuropathy.