Lingual nerve deficit following mandibular third molar removal: review of the literature and medicolegal considerations. Oral Surg Oral Med Oral Pathol Oral Radiol. 2012;113:e10-e18. [PMID: 22669152 DOI: 10.1016/j.tripleo.2011.06.034]

Full life cycle changes of low impacted mandibular third molar associated cystic lesions and adjacent tooth root resorption: a retrospective study

OBJECTIVE

Low impacted third molars are usually asymptomatic and are often found by X-ray examination. The removal of asymptomatic low impacted third molars is one of the most controversial clinical issues in oral and maxillofacial surgery.

METHODS

In this study, 806 patients with low impacted mandibular third molars (LIMTMs) (full bony impaction) were analyzed to determine the prevalence and risk factors for cystic lesions and adjacent tooth root resorption throughout the patients' entire life cycle.

RESULTS

The results showed that the prevalence of adjacent tooth root resorption and cystic lesions was age-related, exhibiting a trend of first increasing and then decreasing; prevalence peaked at the age of 41 to 45 years old, the prevalence rates were 12.50% and 11.11% respectively. And the lowest prevalence rate was 2.86% and 2.44% in ≥ 61 group and 56- to 60-year age group respectively. Age was an independent risk factor for adjacent tooth root resorption of LIMTMs, whereas age and impaction type (especially inverted impaction) were independent risk factors for cystic lesions.

CONCLUSIONS

The full life cycle management strategy for LIMTMs may need to be individualized. Surgical removal is recommended for LIMTMs in patients younger than 41 to 45 years, especially for inverted, mesioangular, and horizontally impacted LIMTMs. LIMTMs in patients older than 41 to 45 years may be treated conservatively with regular follow-up, but surgical removal of inverted impacted LIMTMs is still recommended to avoid cyst formation.

Electrical stimulation to clinically identify position of the lingual nerve: results of 50 subjects with reliability and correlation with MRI

PURPOSE

Recently we described mapping of the lingual nerve clinically in patients using electrical nerve stimulation. This paper reports results of a larger study with inter- and intra-observer reliability and comparison with positional measurements from magnetic resonance imaging (MRI).

METHODS

In 50 healthy participants, measurements were taken when subjects felt a tingling sensation in the tongue induced by a stimulation probe over the lingual nerve. Three positions were measured in relation to the third molar. Measurement reliability was tested for both inter-observer and intra-observer agreement and positional data of the lingual nerve measured clinically was also compared with nerve position as measured from MRI scans.

RESULTS

Out of 50 participants, 96 nerves (49 = left/47 = right) were included in the study. The lingual nerve was identified in 90% (87) of this sample. The mean of height of the nerve in points A, B and C were 9.64 mm, 10.77 mm and 12.34 respectively. Inter-and intra-observer agreement was considered to be good to excellent (ICC = 0.8-0.96). Agreement between nerve mapping measured values and MRI measured values was good (ICC < 0.6).

CONCLUSION

This technique may prove useful for the clinical determination of lingual nerve position prior to procedures in the third molar region.

Characteristics of Mandibular Canal Branches Related to Nociceptive Marker

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

Preoperative informed consent for mandibular third molar surgeries: A survey analysis in a subset of dentists and oral surgeons in Saudi Arabia

Objectives

The objective of this study was to identify patterns of obtaining preoperative informed consent from patients undergoing mandibular third molar surgeries, in a subset of general dentists and oral surgeons in Saudi Arabia, and to compare the consenting patterns based on the clinician’s rank, years of experience, place of work and gender.

Methods

A prospective questionnaire based study was designed and data was obtained through an online survey from 102 participants who were selected for the study. Demographic information, clinician experience, type of informed consent obtained and information related to discussion of legal implications and complications were collected. Descriptive analysis of the obtained data and statistical comparisons using cross tabulation and Pearson Chi-Square test with a 95% significance level (P < 0.05) were done between the independents demographic variables and dependent variables pertaining to patterns of preoperative consenting.

Results

The survey response rate was 81.3% (n = 83), with 59.04% general dentists and 40.96% oral surgeons. The ratio of male to female respondents was approximately 3:1. Majority of the respondents reported a clinical experience of less than 10 years (77.11%) and were reportedly working in the private sector (73.49%). Nearly 80% of the respondents (79.52%) mentioned obtaining preoperative consent for mandibular third molar surgeries and was significantly higher (p-value – 0.018) among clinicians with more than 5 years of experience (90%). While 38.5% of the respondents indicated obtaining both a written and verbal consent, 53.01% obtained only a verbal consent. Majority of the respondents were aware of the legal implications of obtaining informed consent (81.93%) and disclosed incidental complications to their patients (91.57%). However, differences in the perceived post-operative complications associated with mandibular third molar surgeries were observed between general dentists and oral surgeons.

Conclusion

The results of this study indicate a good level of knowledge about informed consent for mandibular third molar surgery and its legal implications among the dentists and oral surgeons who were surveyed. However, to avoid painful medico-legal disputes, a written informed consent signed by patients along with a witness should be considered mandatory.

Somatosensory innervation of the oral mucosa of adult and aging mice

Oral mechanoreception is implicated in fundamental functions including speech, food intake and swallowing; yet, the neuroanatomical substrates that encode mechanical stimuli are not well understood. Tactile perception is initiated by intricate mechanosensitive machinery involving dedicated cells and neurons. This signal transduction setup is coupled with the topology and mechanical properties of surrounding epithelium, thereby providing a sensitive and accurate system to detect stress fluctuations from the external environment. We mapped the distribution of anatomically distinct neuronal endings in mouse oral cavity using transgenic reporters, molecular markers and quantitative histomorphometry. We found that the tongue is equipped with an array of putative mechanoreceptors that express the principal mechanosensory channel Piezo2, including end bulbs of Krause innervating individual filiform papillae and a novel class of neuronal fibers innervating the epithelium surrounding taste buds. The hard palate and gums are densely populated with three classes of sensory afferents organized in discrete patterns including Merkel cell-neurite complexes, Meissner’s corpuscles and glomerular corpuscles. In aged mice, we find that palatal Merkel cells reduce in number at key time-points that correlate with impaired oral abilities, such as swallowing and mastication. Collectively, this work identifies the mechanosensory architecture of oral tissues involved in feeding.

Somatosensory innervation of the oral mucosa of adult and aging mice

Oral mechanoreception is implicated in fundamental functions including speech, food intake and swallowing; yet, the neuroanatomical substrates that encode mechanical stimuli are not well understood. Tactile perception is initiated by intricate mechanosensitive machinery involving dedicated cells and neurons. This signal transduction setup is coupled with the topology and mechanical properties of surrounding epithelium, thereby providing a sensitive and accurate system to detect stress fluctuations from the external environment. We mapped the distribution of anatomically distinct neuronal endings in mouse oral cavity using transgenic reporters, molecular markers and quantitative histomorphometry. We found that the tongue is equipped with an array of putative mechanoreceptors that express the principal mechanosensory channel Piezo2, including end bulbs of Krause innervating individual filiform papillae and a novel class of neuronal fibers innervating the epithelium surrounding taste buds. The hard palate and gums are densely populated with three classes of sensory afferents organized in discrete patterns including Merkel cell-neurite complexes, Meissner's corpuscles and glomerular corpuscles. In aged mice, we find that palatal Merkel cells reduce in number at key time-points that correlate with impaired oral abilities, such as swallowing and mastication. Collectively, this work identifies the mechanosensory architecture of oral tissues involved in feeding.

The differentiation of oral soft- and hard tissues using laser induced breakdown spectroscopy - a prospect for tissue specific laser surgery

Compared to conventional techniques, Laser surgery procedures provide a number of advantages, but may be associated with an increased risk of iatrogenic damage to important anatomical structures. The type of tissue ablated in the focus spot is unknown. Laser-Induced Breakdown-Spectroscopy (LIBS) has the potential to gain information about the type of material that is being ablated by the laser beam. This may form the basis for tissue selective laser surgery. In the present study, 7 different porcine tissues (cortical and cancellous bone, nerve, mucosa, enamel, dentine and pulp) from 6 animals were analyzed for their qualitative and semiquantitative molecular composition using LIBS. The so gathered data was used to first differentiate between the soft- and hard-tissues using a Calcium-Carbon emission based classifier. The tissues were then further classified using emission-ratio based analysis, principal component analysis (PCA) and linear discriminant analysis (LDA). The relatively higher concentration of Calcium in the hard tissues allows for an accurate first differentiation of soft- and hard tissues (100% sensitivity and specificity). The ratio based statistical differentiation approach yields results in the range from 65% (enamel-dentine pair) to 100% (nerve-pulp, cancellous bone-dentine, cancellous bone-enamel pairs) sensitivity and specificity. Experimental LIBS measuring setup.

Profiling intraoral neuropathic disturbances following lingual nerve injury and in burning mouth syndrome

Background

The aim of the study was to analyse intraoral neurophysiological changes in patients with unilateral lingual nerve lesions as well as patients with Burning Mouth Syndrome (BMS) by applying a standardized Quantitative Sensory Testing (QST) protocol.

Methods

The study included patients suffering from a peripheral lesion of the lingual nerve (n = 4), from BMS (n = 5) and healthy controls (n = 8). Neurophysiological tests were performed in the innervation areas of the tongue bilaterally. For BMS patients the dorsal foot area was used as reference.

Results

For patients with peripheral lesion of the lingual nerve the affected side of the tongue showed increased thresholds for thermal (p < 0.05–0.001) and mechanical (p < 0.01–0.001) QST parameters, indicating a hypoesthesia and thermal hypofunction. In BMS patients, a pinprick hypoalgesia (p < 0.001), a cold hyperalgesia (p < 0.01) and cold/warmth hypoesthesia (p < 0.01) could be detected.

Conclusions

The results of this study verified the lingual nerve lesion in our patients as a peripheral dysfunction. The profile showed a loss of sensory function for small and large fibre mediated stimuli. A more differentiated classification of the lingual nerve injury was possible with QST, regarding profile, type and severity of the neurologic lesion. BMS could be seen as neuropathy with variable central and peripheral contributions among individuals resulting in chronic pain.

Delayed onset infections after lower third molar germectomy could be related to the space distal to the second molar

The onset of delayed infection after lower third molar germectomy is influenced by the amount of distal space. This retrospective study aimed to determine whether the incidence of delayed onset infection is related to the space distal to the second molar. The ratio between the distal space and the crown width, measured according to the Ganss protocol on panoramic radiographs, was obtained for 218 surgical germectomies performed for orthodontic reasons in 134 patients. A delayed onset infection occurred following 20 germectomies at between 2 and 8 weeks after surgery; purulent exudates from the alveolus and swelling were present. In 16 of the 20 cases of infection, a Ganss ratio of <0.5 showed the almost complete absence of space distal to the second molar. This study found that the distal space was significantly and inversely correlated with delayed onset infection (P=0.004). From a clinical point of view, it is important for the surgeon to be aware that a higher Ganss ratio may indicate that a delayed onset infection is less likely to occur and that a lower Ganss ratio could indicate a greater likelihood of this type of infection, so that the patient can be properly informed.

How Far Have We Come in the Field of Nerve Regeneration After Trigeminal Nerve Injury?

Patients suffering from nerve injury with sensory disturbances or orofacial pain have greatly reduced quality of life, and it is a big cost for the society. Abnormal sensations caused by trigeminal nerve injury often become chronic, severely debilitating, and extremely difficult to treat. In general, non-invasive treatment such as drug treatment has been insufficient, and there are currently few available effective treatments. Surgical interventions such as end-to-end connection or nerve grafting have disadvantages such as donor site morbidity or formation of neuroma. There is need for optimizing the technique for nerve repair, especially for the trigeminal nerve system, which has so far not yet been well explored. Recently, tissue engineering using biodegradable synthetic material and cell-based therapies represents a promising approach to nerve repair and it has been reported that mesenchymal stem cell (MSC) has an anti-inflammatory effect and seems to play an important role in nerve healing and regeneration.

Unusual Occurrence of Tongue Sensorial Disorder after Conservative Surgical Treatment of Lymphoepithelial Cyst

Lymphoepithelial cyst is a rare lesion of the oral cavity, with the mouth floor being the most common site of occurrence. The therapeutic approach of choice is the surgical treatment, which has rare cases of postoperative complications. The aim of this study is to report the case of a 53-year-old patient who came to Dental Service in the Federal University of Ceará complaining of a small nodular lesion (0.5 cm) located in the ventral tongue. Excisional biopsy was performed and the surgical specimen was submitted for anatomopathological analysis, which found that there was an oral lymphoepithelial cyst. The patient returned after seven days for suture removal and reported loss of sensitivity around the ventral tongue. We prescribed Citoneurin for ten days; however, there was not any significant improvement of the sensitivity. Low frequency laser therapy sessions were applied. The only postoperative symptom was dysesthesia, where there is only a sensitivity decrease. Currently, the patient has a postoperative period of 1 year without recurrence of the lesion. Although previous reports have no described tongue sensorineural disorders associated with this lesion, the occurrence of this event may be related to an unexpected anatomical variation of the lingual nerve.

Implant-related nerve injuries

Injuries to branches of the trigeminal nerves are a known complication during dental implant placement. These injuries tend to be more severe than those experienced during other dentoalveolar procedures. This article reviews the types of nerve injuries and areas and situations of which clinicians should be cognizant when placing dental implants. Strategies to avoid injuries, and a management algorithm for suspected nerve injuries, are also discussed.

Clinical significance of computed tomography assessment for third molar surgery

Surgical extraction of the third molar is the most commonly performed surgical procedure in the clinical practice of oral surgery. Third molar surgery is warranted when there is inadequate space for eruption, malpositioning, or risk for cyst or odontogenic tumor formation. Preoperative assessment should include a detailed morphologic analysis of the third molar and its relationship to adjacent structures and surrounding tissues. Due to developments in medical engineering technology, computed tomography (CT) now plays a critical role in providing the clear images required for adequate assessment prior to third molar surgery. Removal of the maxillary third molar is associated with a risk for maxillary sinus perforation, whereas removal of the mandibular third molar can put patients at risk for a neurosensory deficit from damage to the lingual nerve or inferior alveolar nerve. Multiple factors, including demographic, anatomic, and treatment-related factors, influence the incidence of nerve injury during or following removal of the third molar. CT assessment of the third molar prior to surgery can identify some of these risk factors, such as the absence of cortication between the mandibular third molar and the inferior alveolar canal, prior to surgery to reduce the risk for nerve damage. This topic highlight presents an overview of the clinical significance of CT assessment in third molar surgery.

Lingual nerve injury after third molar removal: Unilateral atrophy of fungiform papillae

BACKGROUND

Pain and sensory changes due to lingual nerve injury are one of the most common alterations that follow surgical removal of third molar. They are usually transient but other less common complications, such as the atrophy of fungiform papillae, have an uncertain prognosis.

CASE DESCRIPTION

We report a case of a 34-year-old woman who presented a unilateral lingual atrophy of fungiform papillae after third molar extraction accompanied by severe dysesthesia that altered her daily life significantly during the following months and how this complication evolved over time. We conducted a literature review on the different factors that can lead to a lingual nerve injury.

CLINICAL IMPLICATIONS

The clinical evolution of temporary and permanent somatosensitve injuries is an important fact to take into consideration during the postoperative management because it will indicate the lesion prognosis. Key words:Lingual nerve, third molar removal, somatosensitive alteration, papillae atrophy, permanent injury, temporary injury.

Informed consent in orthognathic surgery

Historically, the patient-doctor relationship has been based on trust. Adequately informing a patient confirms this relationship and fulfills the legal obligation of the physician to inform the patient to the best of his knowledge. Informed consent is the process of providing patients with the realistic and necessary information in a manner which they can understand and recall and allows them voluntarily to make an informed choice on the treatment. In this article, the current knowledge about informed consent in orthognathic surgery is reviewed and discussed.

A Four-Year Monocentric Study of the Complications of Third Molars Extractions under General Anesthesia: About 2112 Patients

Introduction. The aim of this study was to assess the complications resulting from third molar extraction under general anesthesia. Material and Methods. The retrospective study included all patients who underwent impacted third molars extraction from January 2008 until December 2011. 7659 third molars were extracted for 2112 patients. Postoperative complications were retrieved from medical files. Results. No complications were related to general anesthesia. The most frequent postoperative complication was infection (7.15%). Lingual nerve injuries affected 1.8% of the patients. All of them were transient and were not related to tooth section. Inferior alveolar nerve injuries were reported in 0.4% of the cases. 95.8% of these patients were admitted for one-day ambulatory care, and only two patients were readmitted after discharge from hospital. Discussion. This surgical technique offers comfort for both surgeons and patients. Risks are only linked to the surgical procedure as we observed no complication resulting from general anesthesia. One-day hospitalization offers a good balance between comfort, security, and cost. The incidence of complications is in agreement with the literature data, especially regarding pain, edema, and infectious and nervous complications. It is of utmost importance to discuss indications with patients, and to provide them with clear information.

Pathological mandibular fractures: a review of the literature of the last two decades

Pathological mandibular fractures are rare, accounting for fewer than 2% of all fractures of the mandible. They could be defined as fractures that occur in regions where bone has been weakened by an underlying pathological process. Pathological fractures usually may follow surgical interventions such as third molar removal or implant placement, result from regions of osteomyelitis, osteoradionecrosis, and bisphosphonate-related osteonecrosis of the jaw, occur because of idiopathic reasons or be facilitated by cystic lesions, benign, malignant, or metastatic tumors. Pathological mandibular fractures may be challenging to treat because of their different etiology and peculiar local and general conditions, often requiring a more rigid fixation. In patients with poor medical conditions, simpler and more limited options may be preferred.