Effects of different types of injury to the inferior alveolar nerve on the behavior of Schwann cells during the regeneration of periodontal nerve fibers of rat incisor.
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The present study reports on different regeneration patterns of axons and Schwann cells in the periodontal ligament of the rat incisor using immunohistochemistry of protein gene product 9.5 (PGP 9.5) and S-100 protein. Three kinds of injury (transection, crush and segmental resection) were applied to the inferior alveolar nerve. In normal animals, PGP 9.5- and S-100-immunoreactivities were detected in the axons and Schwann cell elements of periodontal Ruffini endings, respectively. They were restricted to the alveolus-related part, occurring only rarely in the tooth-related part and in the shear zone (the border between the alveolus-related and tooth-related parts). Both transection and segmental resection caused the complete disappearance of PGP 9.5-immunoreactive nerve fibers in the periodontal ligament, while a small number of them could be found following the crush injury. Regenerating PGP 9.5-reactive nerve fibers appeared at 5 days and 21 days following the transection and segmental resection, respectively. The regeneration of periodontal nerve fibers completed in a period of 21-28 days and 14-21 days following the transection and crush, respectively, but was not completed even at 56 days following the segmental resection. The behavior of Schwann cells during regeneration was similar after the different nerve injuries; spindle-shaped S-100-immunoreactive cells, presumably Schwann cells, appeared in the shear zone and the tooth-related part. These cells disappeared 5-7 days prior to the completion of the regeneration of axonal elements of the periodontal ligament following the transection and crush. Following the segmental resection, in contrast, spindle-shaped S-100-positive cells disappeared from the tooth-related part at 42 days, although the axonal regeneration of periodontal Ruffini endings proceeded even until 56 days. We thus conclude that the duration of the migration of Schwann cells depends on the state of the regeneration of axons. (+info)
Clinical evaluation of inferior alveolar nerve block by injection into the pterygomandibular space anterior to the mandibular foramen.
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The conventional inferior alveolar nerve block (conventional technique) has potential risks of neural and vascular injuries. We studied a method of inferior alveolar nerve block by injecting a local anesthetic solution into the pterygomandibular space anterior to the mandibular foramen (anterior technique) with the purpose of avoiding such complications. The insertion angle of the anterior technique and the estimation of anesthesia in the anterior technique were examined. The predicted insertion angle measured on computed tomographic images was 60.1 +/- 7.1 degrees from the median, with the syringe end lying on the contralateral mandibular first molar, and the insertion depth was approximately 10 mm. We applied the anterior technique to 100 patients for mandibular molar extraction and assessed the anesthetic effects. A success rate of 74% was obtained. This is similar to that reported for the conventional technique but without the accompanying risks for inferior alveolar neural and vascular complications. (+info)
Links between anaesthetic modality and nerve damage during lower third molar surgery.
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OBJECTIVE: To investigate the relationships between eruption status, gender, social class, grade of operator, anaesthetic modality and nerve damage during third molar surgery. DESIGN: Two centre prospective longitudinal study. SETTING: The department of oral and maxillofacial surgery, University Hospital Birmingham NHS Trust and oral surgery outpatient clinics at Birmingham Dental Hospital. SUBJECTS: A total of 391 patients had surgical removal of lower third molars. Sensory disturbance was recorded at one week post operatively. Patients with altered sensation were followed up at one month, three months and six months following surgery. RESULTS: 614 lower third molars in 391 patients were removed. Forty-six procedures (7.5%) were associated with altered sensation at one week with three procedures (0.49%) showing persistent symptoms at six months. Of these 46 nerve injuries, 26 (4.23%) involved the lingual nerve and 20 (3.25%) the inferior dental nerve (IDN). All three persistent sensations were IDN related. A logistic regression model found that the use ofa lingual retractor chi2 = 11.559, p = 0.003 was more significant than eruption status chi2 = 12.935, p = 0.007. There was no significant relationship between anaesthetic modality, age, social class, sex and seniority of operator. CONCLUSIONS: There was no link between the choices of local or general anaesthesia and nerve damage during lower third molar removal when difficulty of surgery was taken into account. (+info)
Reconstruction of the inferior alveolar nerve by autologous graft: a retrospective study of 20 cases examining donor nerve length.
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The purpose of this study was to confirm the length and kind of donor nerves used in nerve grafts for reconstruction of inferior alveolar nerve defects. The authors conducted a retrospective study of surgeries that were performed between 1977 and 1996. A total of 20 patients underwent nerve grafting procedures during this period. The greater auricular nerve was selected as the donor nerve in 16 cases, while the sural nerve was selected in 4. Mean lengths of donor nerves were 7.28 +/- 1.6 cm and 11.5 +/- 3.4 cm for the greater auricular and sural nerves, respectively. As indicated, the sural nerves were significantly longer (p < 0.01). Mean lengths of donor nerves grafted for partial resection and hemi-mandibulectomy were 7.23 +/- 1.6 cm and 10.8 +/- 3.4 cm, respectively. Statistical analysis indicated that grafts used in the hemi-mandibulectomy group were significantly longer (p < 0.05). In terms of types of donor nerve used in mandibulectomies, the greater auricular nerve was used in the majority of partial resections, and the sural nerve was employed for hemi-mandibulectomy. (+info)
MR imaging of traumatic lesions of the inferior alveolar nerve in patients with fractures of the mandible.
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BACKGROUND AND PURPOSE: The objective of this study was to assess whether MR imaging can image the neurovascular bundle in patients with fractures of the mandible. In addition, an attempt was made to evaluate whether MR images provide information regarding the continuity of the inferior alveolar nerve before surgery and regarding signal intensity changes after trauma. METHODS: We analyzed preoperative MR images of 23 patients with mandibular fractures. Object-oriented sagittal view proton density- and T1-weighted sequences (before and after the administration of contrast agent) were used not only in an attempt to obtain purely qualitative information regarding nerve continuity in the neurovascular bundle (inferior alveolar nerve, artery, vein) but also to perform quantitative region-of-interest measurements of signal intensities at four defined measurement sites. The measurements were compared with those obtained for a patient population with healthy mandibles. RESULTS: It was possible to interpret MR images in 21 cases. MR imaging findings showed that the neurovascular bundle had been cut in two patients and was intact in the remaining 19 patients. These MR imaging findings were confirmed intraoperatively in all cases. Although we found no significant signal intensity differences between patients with intact nerves and patients with cut nerves, we found significant differences between patients with mandibular fractures and patients with unremarkable mandibles. CONCLUSION: It is possible to diagnose the interruption of nerve continuity by using MR imaging. Signal intensity measurements in the neurovascular bundle provide no information regarding nerve continuity. (+info)
Inferior alveolar nerve paresthesia relieved by microscopic endodontic treatment.
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We experienced two cases of inferior alveolar nerve paresthesia caused by root canal medicaments, which were successfully relieved by microscopic endodontic treatment. In the first case, the paresthesia might have been attributable to infiltration of calcium hydroxide into the mandibular canal through the root canals of the mandibular left second molar tooth. In the second case, the paresthesia might have been attributable to infiltration of paraformaldehyde through the root canals of the mandibular right second molar tooth. The paresthesia was relieved in both cases by repetitive microscopic endodontic irrigation using physiological saline solution in combination with oral vitamin B12 and adenosine triphosphate. (+info)
Inferior alveolar nerve injury caused by thermoplastic gutta-percha overextension.
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Injuries to the inferior alveolar nerve following trauma resulting in a mandibular fracture are well documented and are a well-known risk when surgical procedures are planned for the mandible in the region of the inferior alveolar canal. Such injuries are relatively rare following endodontic therapy. This article reports a case of combined thermal and pressure injury to the inferior alveolar nerve, reviews the pathogenesis of such an injury and makes suggestions for its management. (+info)
Iatrogenic paresthesia in the third division of the trigeminal nerve: 12 years of clinical experience.
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BACKGROUND: Iatrogenic paresthesia in the third division of the trigeminal nerve remains a complex clinical problem with major medicolegal implications. However, most lawsuits can be prevented through better planning of procedures and by obtaining informed consent. The purpose of this article is to present the authors" clinical experience over the past 12 years, to review the principles of prevention and management of trigeminal paresthesia and to highlight the resulting medicolegal implications. METHODS: The files of all 165 patients referred to the oral and maxillofacial surgery department for evaluation of iatrogenic paresthesia in the third division of the trigeminal nerve were reviewed. The characteristics of the subgroup of patients who had taken an attending dentist to court were compared with those of the other patients. RESULTS: Surgical extraction of impacted molars was the main cause of paresthesia in 109 (66%) of the 165 subjects. The alveolar nerve was affected in 89 (54%) subjects, the lingual nerve in 67 (41%) subjects, and both nerves were affected in 9 (5%) subjects. There were more female than male patients (ratio 2.2:1). Lawsuits were initiated in 33 (20%) of the cases; patients who initiated lawsuits were younger, were more likely to have experienced anesthesia and were more likely to need microsurgery (all p < 0.001). Poor surgical planning and lack of informed consent were the most common errors on the part of the dentists. CONCLUSIONS: An accurate evaluation of surgical indications and risk, good surgical technique, preoperative informed consent and sufficient postoperative follow-up should help to reduce the frequency of neurosensory deficits after dental treatment and attendant lawsuits. (+info)