Risk factors of nerve injury during mandibular sagittal split osteotomy

There is little objective data about whether surgical technique or mandibular anatomy are a risk for inferior alveolar nerve (IAN) injury during bilateral sagittal split osteotomy (BSSO). Orthodromic sensory nerve action potentials (SNAPs) of the IAN were continuously recorded on both sides in 20 patients with mandibular retrognathia during BSSO operation. Changes in latency, amplitude, and sensory nerve conduction velocity (SNCV) at baseline and at different stages of the operation were analyzed. The SNAP latencies prolonged, the amplitudes diminished, and the SNCVs slowed down during BSSO (P = 0.0000 for all parameters). The most obvious changes occurred during surgical procedures on the medial side of the mandibular ramus. There was a clear tendency towards more disturbed IAN conduction with longer duration of these procedures (right side R = -0.529. P = 0.02; left side R = -0.605, P = 0.006). Exposure or manipulation of the IAN usually had no effect on nerve function, but the IAN conduction tended to be more disturbed in cases with nerve laceration. Low corpus height (R = 0.802, P = 0.001) and the location of the mandibular canal near the inferior border of the mandible (R = 0.52, P = 0.02) may increase the risk of IAN injury. There was no correlation between the age of the patients and the electrophysiological grade of nerve damage.     

Lower lip paraesthesia following restoration of a second premolar tooth. Case report

A forty year old female patient developed paraesthesia of the right side of her lower lip following the placement of an extensive pin-retained amalgam restoration in her lower right second premolar tooth. Radiographs indicated that the mental foramen was close to the apex of this tooth and it was assumed that postoperative pulpitis and periapical inflammation had caused the paraesthesia through the effects of pressure on the mental nerve. The paraesthesia resolved following endodontic treatment of the lower second premolar tooth and the patient has had no further signs or symtoms.     

Aglossia: a case report

A female child of 4 years with congenital absence of tongue has been described. This anomaly is usually associated with other congenital defects particularly limb and other cranio-facial defects. But in this case, the child enjoys the normal life, the unusual absence of tongue; she used to go to school play around with her friends and had a comparable I.Q.     

Poland-Moebius syndrome: a case with oral anomalies

The combination of Moebius and Poland anomalies is rarely described in the literature. While some authors believe this association is an independent syndrome, others think that Poland, Moebius and Poland-Moebius syndromes are variations of the same condition. We report a case of Poland-Moebius syndrome in a 6-year-old girl who presented with bilateral convergent strabismus, the inability to abduct her eyes beyond the midline and brachydactyly of her right hand. Oral manifestations included incompetent lips and an abnormal tongue. Other facial features included hypoplasia of her mandible and her left ear at a slightly lower level than her right ear. Panoramic and lateral skull radiographs confirmed the absence of certain teeth and the hypoplastic mandible. The diagnosis of Poland-Moebius syndrome was made on the basis of cranial nerve involvement and oro-facial manifestations.     

Displaced calcium hydroxide paste causing inferior alveolar nerve paraesthesia: report of a case

A patient presented with an intraoral red, painful, and hard swelling in the lower right jaw. Radiographs showed a 2 x 1 cm area of radiopaque material surrounding the apex of the second premolar. The material, according to the patient's dentist, was calcium hydroxide paste used as a temporary dressing material in the root canal. The patient developed paraesthesia in her lower lip probably due to a neurotoxic effect caused by calcium hydroxide. The foreign material was surgically excavated from the spongious bone, directly adjacent to the nerve, and the patient later regained her sensation in the lip. A histopathological analysis revealed necrosis, deposits of foreign bodies, and inflammatory cells and foreign-body giant cells. This report illustrates the toxicity and adjacent clinical symptoms of calcium hydroxide paste when displaced into bone tissue close to the alveolar inferior nerve. It also demonstrates the benefits of removing such displaced material before symptoms progress.     

Enzyme-histochemical and morphological characteristics of muscle fibre types in the human buccinator and orbicularis oris

Human masticatory muscles, originating from the first branchial arch and innervated by the trigeminal nerve, have a fibre composition distinct from that of limb and trunk muscles. The zygomatic muscles, originating from the second branchial arch and innervated by the facial nerve, differ in fibre composition from either the masticatory or the limb and trunk muscles. To elucidate further the structural basis for function, and the influence of embryological origin and innervation on oro-facial muscles, the buccinator and orbicularis oris muscles, which originate from the second branchial arch and are innervated by the facial nerve, were investigated. Like the masticatory and zygomatic muscles, they have a large representation in the cerebral cortex. Both muscles were composed of type I, type IIA and a few type IIC fibres of about equal diameter. However, the type I fibres had a different myofibrillar ATPase reaction from those in masticatory, zygomatic, limb and trunk muscles; this was a moderate to strong staining at pH 9.4, indicating a special isomyosin composition. Whereas the buccinator was composed of 53% type I fibres, the orbicularis oris had a 71% predominance of type II fibres. In both muscles, the mean fibre diameter and its marked intramuscular variability were similar to earlier findings in the zygomatic muscles. No muscle spindles were found. The large number of type I fibres in the buccinator implies a capacity for endurance during continuous work at relatively low levels of force. The predominance of type II fibres in the orbicularis oris indicates that it is built up of fast-twitch motor units, related to properties such as rapid acceleration and high speed during intermittent oro-facial movements. The similarities and differences in fibre-type composition between the facial, masticatory and limb muscles imply that specific functional demands are of greater importance for muscle differentiation than embryological origin and nerve supply.     

Decreased nerve distribution in mixed venous-lymphatic malformation

In order to investigate the nerve distribution in mixed venous-lymphatic malformations (MVLMs), 57 postoperative patients diagnosed with MVLMs of the tongue were selected. Immunohistochemistry staining for neurofilament (NF) was used to detect sensory nerve fibers. Distribution of NF in samples from MVLMs was compared with distribution of NF in normal tongue tissue, venous malformations, lymphatic malformations and venular malformations. Results showed that the number of NF-positive nerve fibers in MVLMs was comparable to that in venous malformations and lymphatic malformations. The number of nerve fibers in MVLMs was significantly lower than in normal tissues. NF distribution in MVLMs was not affected by the patient's age or the coexistence of infection. These data suggest that the decreased distribution of sensory nerve fibers in MVLMs may be involved in the pathogenesis of MVLM of the tongue.     

A light microscopical study on the structure of traumatic neuromas of the human lingual nerve

OBJECTIVE: To determine the morphologic characteristics of traumatic neuromas resulting from damage to the lingual nerve during the surgical removal of lower third molar teeth. STUDY DESIGN: Using light microscopy, we examined hematoxylin and eosin-stained sections of neuromas removed at the time of microsurgical nerve repair in 31 patients. Changes in fascicular pattern were quantified and evidence of inflammation was recorded. Statistical comparisons were made between the sections from patients with and without symptoms of dysesthesia, and with sections of normal lingual nerve obtained from organ donor retrieval patients. RESULTS: The neuromas were found to contain large numbers of small and haphazardly arranged regenerating nerve fascicles within a densely collagenous and fibroblastic stroma. The mean number of fascicles was 31 (+/- SD 28) in normal lingual nerve, but 462 (+/- 366) within traumatic neuromas. Mean fascicle diameter was 44 (+/- 10) microm in neuromas, but 273 (+/- 101) microm in normal nerve. A chronic mononuclear cell inflammatory infiltrate was observed in 42% of neuroma specimens, and histologic signs of inflammation were frequently seen in patients with symptoms of dysesthesia. CONCLUSIONS: Damage to the lingual nerve during third molar removal results in marked changes to the fascicular pattern and sometimes the presence of chronic inflammation in the injured nerve. These changes could contribute to the altered electrophysiological properties of axons trapped within traumatic neuromas, but we found no significant differences between the specimens studied from patients with or without symptoms of dysesthesia.     

The key to profound local anesthesia: neuroanatomy

BACKGROUND: To achieve profound dental local anesthesia, it is necessary for the dentist to have a thorough knowledge of the details of sensory innervation to the maxilla and mandible. Since the early 1970s, dentistry has experienced a resurgence of interest in the neuroanatomical basis of local anesthesia, resulting in numerous scientific reports on the subject. OVERVIEW: Current studies afford a more detailed knowledge of the branching of various divisions of the trigeminal nerve, the great sensory nerve of the head region. In this article, the authors provide an update of the peripheral distribution of the trigeminal nerve to enhance induction of safe and effective dental local anesthesia. CONCLUSIONS AND PRACTICAL IMPLICATIONS: An understanding of the potential variations in innervation should help the dentist improve his or her ability to induce profound local anesthesia.     

Comparative assessment of Oral Hygiene and Periodontal status among children who have Poliomyelitis at Udaipur city,Rajasthan, India

Objective: To assess and compare the oral hygiene and periodontal status among children with Poliomyelitis having upper limb disability, lower limb disability and both upper and lower disability at Udaipur city, Rajasthan, India. Study design: Total sample comprised of 344 Poliomyelitis children (upper limb disability: 33.4%; lower limb disability: 33.7%; both upper and lower limb disability: 32.9%) in the age group of 12-15 years. Clinical examination included recording Simplified Oral Hygiene Index and Community Periodontal Index. Analysis of variance (ANOVA), multiple logistic and stepwise linear regression were used for statistical analysis. Results: The mean OHI-S (2.52±1.05) score was found to be highest among children who had both upper and lower limb disability (p<0.05). The highest and lowest mean number of healthy sextants were found among those with only lower limb disability (4.53±2.05) and among those with both upper and lower limb disability (0.77±1.39), respectively (p<0.05). Stepwise multiple linear and multiple logistic regression analysis showed that the best predictor for oral hygiene and periodontal status was limb involved in the disability. Conclusion: The results of the study depicted an overall poor oral hygiene and periodontal status of the group. It was recognized that limbs involved in the disability had an impact on the oral hygiene and periodontal condition. The situation in this specialized population draws immediate attention for an integrated approach in improving the oral health and focus towards extensive research. Key words:Poliomyelitis, upper limb disability, lower limb disability, oral hygiene, periodontal status.     

A case of Collet–Sicard Syndrome presenting to the Oral and Maxillofacial Surgery Department and a review of the literature

A case of Collet–Sicard Syndrome caused by skull base metastasis of probable breast adenocarcinoma is reported. A 79-year-old lady presented to the Oral and Maxillofacial Surgery Department with progressive left-sided tongue symptoms that she described as swelling. This was initially attributed to local disease, and a biopsy showed the patient was suffering from Necrotizing Sialometaplasia. However, her symptoms rapidly evolved into cranial nerve palsies affecting IX–XII, not initially diagnosed. Subsequent imaging revealed the cause of her worsening symptoms to be a metastatic lesion at her left skull base. Cranial nerve palsies due to metastases to the skull base are rare, and the authors would advise clinicians to adopt a high-index of suspicion in ruling out cranial nerve pathology at the skull base when encountering unusual signs and symptoms in the head and neck region.     

The retromolar canal (foramen retromolare). Overview and case report

A 19-year old female patient was referred for removal of her wisdom teeth. The panoramic radiograph showed bilateral retromolar canals in the mandible. Since the retromolar canal is neglected in anatomical textbooks and is rarely documented in scientific publications, the case prompted us to perform further diagnostic examinations with informed consent by the patient. A limited cone beam computed tomography was made and, during the surgical removal of the patient's lower right wisdom tooth, a biopsy of the soft tissue bundle emerging from the retromolar foramen was taken. In accordance with the literature, the histology revealed myelinated nerve fibers, small arteries and venules. The limited data available in the literature about the retromolar canal report that this bony canal may convey an aberrant buccal nerve. In addition, sensory nerve fibers entering the retromolar canal from above and branching to the mandibular molars may evade a block anesthesia at the mandibular foramen. These rare anatomic features may explain why the elements of the retromolar canal account for failures of mandibular block anesthesia or postsurgical sensitivity changes in the supply area of the buccal nerve.     

Transposition of the mental nerve by piezosurgery followed by postoperative neurosensory control: a case report

Transposition of the mental nerve is a preprosthetic procedure that is effective for patients with hyperaesthesia caused by the effect of a dental prosthesis on the alveolar ridge. We present the case of a 74-year-old woman with pain and hyperaesthesia of the right inferior alveolar nerve caused by a dental prosthesis. Caudal transposition of the right mental nerve by piezosurgery resulted in postoperative neurosensory controls of the lower lip showing normal nerve function 2 months later.     

Ultrastructural characteristics of axons in traumatic neuromas of the human lingual nerve

AIMS: To determine the ultrastructural characteristics of axons in traumatic neuromas of the human lingual nerve during the surgical removal of lower third molar teeth and to establish whether any characteristics were different between patients with dysesthesia and patients without dysesthesia. METHODS: Transmission electron microscopy was used to determine the ultrastructural morphological characteristics of human lingual nerve neuromas (n = 34) removed at the time of microsurgical nerve repair. From a sample population of myelinated and nonmyelinated fibers within the neuromas, fiber diameter, myelin thickness, g-ratio, and the number of mitochondria per axon were quantified. Comparisons were made with normal control lingual nerve specimens (n = 8) removed at the time of organ donor retrieval. RESULTS: Significant differences in ultrastructural morphology were found between the neuromas and control nerves. The neuromas contained a higher proportion of small (2- to 8-microm diameter) myelinated nerve fibers than controls, and the mean myelinated fiber diameter was significantly lower in neuromas than in controls. Mean myelin sheath thickness was significantly thinner in neuromas (0.6 +/- 0.1 microm) than in controls. However, the g-ratio, which is a measure of the myelination status of the nerve fibers in relation to their diameter, was found to be similar in each group, suggesting a normal process of myelination in the damaged axons. Nonmyelinated axon diameter was also significantly smaller in the neuromas than in the controls, and Schwann cells were found to sheathe more nonmyelinated axons in neuromas than in controls. The ratio of nonmyelinated to myelinated axons was significantly higher in neuromas than in controls. However, no significant differences were found between patients with dysesthesia and those without dysesthesia. CONCLUSION: Damage to the lingual nerve results in marked changes to axon diameter, myelin sheath thickness, and Schwann cell-axon relationships. These ultrastructural changes could contribute to the altered electrophysiological properties of axons trapped within neuromas. However, no significant differences in the ultrastructural characteristics studied were found between specimens from patients with or without symptoms of dysesthesia.     

Bilateral congenital trigeminal sensorimotor neuropathy presents as a severe open-bite malocclusion

Trigeminal neuropathy is commonly seen as a disorder of sensation in the distribution of the fifth cranial nerve. An 18-year-old girl was referred to our hospital because of a severe anterior open-bite deformity with a long face after presurgical orthodontic treatment. Surgical plan was maxillary posterior impaction with anterior advancement, mandibular setback operation, and genioplasty with vertical chin reduction in one stage. One month after surgery she had still difficulty closing her mouth. With the help of her hands, she could close her mouth fully on normocclusion. Weakness of the jaw-closing muscles was confirmed with muscle testing. She had impaired sensation to light touch and pinprick in the distribution of the maxillary and mandibular divisions of the bilateral trigeminal nerves. T1-weighed MRI of the brain showed bilaterally atrophy of the muscles innervated by the trigeminal motor nerve (i.e., the masseter, medial and lateral pterygoids, and temporalis muscles). We thoroughly evaluated our patient through history and clinical, laboratory, electrophysiological, and radiological examinations. The motor and the sensory V2 and V3 branches of the trigeminal nerve were congenitally damaged. As far as we know, this case is the first bilateral congenital trigeminal sensorimotor neuropathy presented with maxillo-mandibular and a severe open-bite deformity.     

Traumatic neuroma in the lower lip arising following laser/cryosurgery to treat a mucocele

A 15-year-old girl presented with a painless recurrent swelling on her right lower lip mucosa for about 10 months. She had a past history of treatment with laser surgery and cryosurgery. The clinical diagnosis was a 'recurrent mucocele'. Histopathological examination of the surgical specimen revealed a mucocele close to a neuroma with irregular nerve fascicles, leading to a diagnosis 'mucocele accompanied with a traumatic neuroma'. In the present report, the traumatic neuroma appears to have arisen following laser or cryosurgery.     

Cerebellopontine angle mass mimicking lingual nerve injury after dental implant placement: a case report

This is a rare case report of a cerebellopontine angle (CPA) mass mimicking lingual nerve injury after a dental implant placement. Lingual nerve injury is a common complication following dental implant placement. CPA masses are likely to cause symptomatic trigeminal neuralgia, and thus can mimic and be easily confused with oral diseases. We experienced a case of CPA mass mimicking lingual nerve injury after dental implant placement. The patient was a 57‐year‐old Japanese female who complained of glossalgia. She underwent dental implant placement in the mandible before visiting our clinic. Panoramic x‐ray radiography revealed no abnormalities; the salivary flow rate by gum test was 7.0 ml/10 min. She was diagnosed with lingual nerve injury and secondary burning mouth syndrome. Vitamin B12 and oral moisturizer did not provide relief; furthermore, numbness in the lower lip emerged. A Semmes Weinstein test demonstrated elevation of her sensitivity threshold. Finally, magnetic resonance imaging revealed a 20‐mm diameter mass in the CPA. The patient is now being followed under conservative management. Our experience underscores the importance of including CPA mass in the differential diagnosis of dental diseases.     

Characteristics of periodontal mechanoreceptors supplying reimplanted canine teeth in cats

These characteristics were investigated 12 weeks and one year after tooth reimplantation. Electrophysiological recordings were made from single mechanosensitive units dissected from the inferior alveolar nerve and each unit was characterized by applying forces to the crown of the tooth. The characteristics were compared with those of receptors innervating normal teeth. The periodontal mechanoreceptors supplying teeth reimplanted 12 weeks earlier responded to applied forces over a narrower range of directions, had higher force thresholds, lower discharge frequencies and adapted more rapidly than controls. One year after reimplantation their characteristics were nearer to normal but they remained significantly different from those of control units. It seems likely that the altered receptor characteristics could have resulted from a combination of changes in tooth mobility, disorganisation of the collagen matrix and direct injury to the nerve terminals.     

血管化游离腓骨瓣下颌骨缺损重建的供区并发症及功能评价

目的:评价血管化游离腓骨瓣下颌骨重建患者的供区并发症及功能情况.方法:游离腓骨瓣下颌骨重建41例,通过临床检查及Enneking下肢功能量表评价围手术期及术后6月后的供区并发症及功能情况.结果:2例供区出现围手术期感染;术后6月后,所有患者踝关节稳定性良好,2例出现踝关节的背屈运动受限,19例(46.3%)出现指足脚拇趾运动受限;患者下肢功能总体恢复良好.结论:游离腓骨瓣下颌骨重建术后对患者下肢功能影响较轻.     

Trigeminal somatosensory evoked potentials: a normal value study.

Normal somatosensory evoked potentials were obtained from the lower lip of 40 volunteers. Efforts were made to exclude artefact. A consistent triphasic wave form of three peaks and troughs was defined. There were greater variations in amplitude than latency between subjects. Statistically, one side of the lower lip can be used as a control for the contralateral side, but it may not be possible to have reliable normal values between subjects. Somatosensory evoked potentials may however represent an objective method of evaluating trigeminal sensory nerve function.