Neuropathic implications of prosthodontic treatment

Neurological Complications following Surgical Treatments of the Lower Molars

Aim

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

Materials and Methods

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

Conclusions

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

miRNA contributes to neuropathic pains

Neuropathic pain (NP) is a kind of chronic pain caused by direct injury to the peripheral or central nervous system (CNS). microRNAs (miRNAs) are small noncoding RNAs that mostly interact with the 3 untranslated region of messenger RNAs (mRNAs) to regulate the expression of multiple genes. NP is characterized by changes in the expression of receptors and mediators, and there is evidence that miRNAs may contribute to some of these alterations. In this review, we aimed to fully comprehend the connection between NP and miRNA; and also, to establish a link between neurology, biology, and dentistry. Studies have shown that targeting miRNAs may be an effective therapeutic strategy for the treatment of chronic pain and potential target for the prevention of NP.

Therapy of Neurophysiological Changes after Oral and Maxillofacial Surgery—A Systematic Review

Introduction: The purpose of this systematic review was to critically analyze the recent literature to present a guideline for management of neurophysiological changes after implant placement and oral and maxillofacial surgical procedures. Materials and methods: Three electronic databases and manual search approaches were used to identify relevant articles on neurophysiological changes. Only studies with a randomized controlled study design were included. Primary outcome was defined as the status of recovery and relief of pain states under various therapies. Two independent reviewers evaluated the data. Results: A total of eight studies from 2891 records identified met the inclusion criteria. Therapy options for patients with neurophysiological changes after implant placement and oral and maxillofacial surgery were low-level laser (LLL), stellate ganglion block (SGB), medication, and surgical removal of implants. Six studies dealt with LLL, providing a significant improvement in mechanical sensation. Only one study revealed the whole neurosensory profile including neuropathic pain states. All the included RCT studies presented at least one bias, and a considerable heterogeneity of the included studies was revealed. Conclusions: Reduced thermal sensation may be due to irritation of small fibers. LLL might help to improve nerve recovery.

Persistent pain and neurosensory disturbance after dental implant surgery: pathophysiology, etiology, and diagnosis

Many studies have documented the successful outcomes of dental implants, but have also reported the association of sensory disturbances with the surgical implant procedure. Postsurgical pain is a normal response to tissue injury, and usually resolves after the tissue heals. However, some patients who receive dental implants experience persistent pain even after normal healing. This article describes the basic anatomy and pathophysiology associated with nerve injury. The incidence and diagnosis of these problems, in addition to factors that result in the development of chronic persistent neuropathic pain and sensory disturbances associated with surgical implant placement, are discussed.

Simultaneous inferior alveolar nerve regeneration and osseointegration with a nerve growth factor-supplying implant: a preliminary study

PURPOSE

Although nerve growth factor (NGF) has been proved to enhance inferior alveolar nerve (IAN) regeneration, its clinical application remains a challenging issue. This study investigated the functional regeneration of IAN injury by supplying NGF using an NGF-supplying implant and its effect on the osseointegration.

MATERIALS AND METHODS

In canine IAN transection-and-repair models (n = 9), NGF-supplying implants connected to osmotic pumps were installed just above the transection site. In the right IAN, NGF 300 μg in phosphate buffered saline (PBS) 2 mL was loaded in the pump and pure PBS 2 mL was loaded in the left IAN. The gross clinical finding was evaluated by wound healing, inflammation, implant exposure, and loss of fixture. To evaluate IAN regeneration, electrophysiologic (amplitude, latency, conduction velocity, and peak voltage) and histomorphometric (axon count and density, myelin thickness, and ratio of axon diameter to fiber diameter) analyses were performed. Implant stability quotient, bone-to-implant contact ratio, and new bone area were measured to assess the osseointegration of the NGF-supplying implant.

RESULTS

The conduction velocity (2.675 m/second) and peak voltage (1.940 μV) of the NGF group at 6 weeks were considerably higher than those of the PBS group (1.892 m/second and 1.300 μV, respectively). The same results were observed for axon count (NGF vs PBS, 4,576.107 ± 270.413 vs 3,606.972 ± 242.876), axon density (10,707.458 ± 638.835 vs 7,899.781 ± 1,063.625/mm(2)), and myelin thickness (1.670 ± 0.555 vs 1.173 ± 0.388 μm). There were no meaningful differences for the other parameters.

CONCLUSIONS

Supplying NGF with specially designed dental implants can be a new therapeutic approach to enable IAN regeneration and osseointegration simultaneously.

Clinical and radiological classification of the jawbone anatomy in endosseous dental implant treatment

Objectives

The purpose of present article was to review the classifications suggested for assessment of the jawbone anatomy, to evaluate the diagnostic possibilities of mandibular canal identification and risk of inferior alveolar nerve injury, aesthetic considerations in aesthetic zone, as well as to suggest new classification system of the jawbone anatomy in endosseous dental implant treatment.

Material and Methods

Literature was selected through a search of PubMed, Embase and Cochrane electronic databases. The keywords used for search were mandible; mandibular canal; alveolar nerve, inferior; anatomy, cross-sectional; dental implants; classification. The search was restricted to English language articles, published from 1972 to March 2013. Additionally, a manual search in the major anatomy and oral surgery books were performed. The publications there selected by including clinical and human anatomy studies.

Results

In total 109 literature sources were obtained and reviewed. The classifications suggested for assessment of the jawbone anatomy, diagnostic possibilities of mandibular canal identification and risk of inferior alveolar nerve injury, aesthetic considerations in aesthetic zone were discussed. New classification system of the jawbone anatomy in endosseous dental implant treatment based on anatomical and radiologic findings and literature review results was suggested.

Conclusions

The classification system proposed here based on anatomical and radiological jawbone quantity and quality evaluation is a helpful tool for planning of treatment strategy and collaboration among specialists. Further clinical studies should be conducted for new classification validation and reliability evaluation.

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

Objectives

The purpose of present article was to review aetiological factors, mechanism, clinical symptoms, and diagnostic methods as well as to create treatment guidelines for the management of inferior alveolar nerve injury during dental implant placement.

Material and Methods

Literature was selected through a search of PubMed, Embase and Cochrane electronic databases. The keywords used for search were inferior alveolar nerve injury, inferior alveolar nerve injuries, inferior alveolar nerve injury implant, inferior alveolar nerve damage, inferior alveolar nerve paresthesia and inferior alveolar nerve repair. The search was restricted to English language articles, published from 1972 to November 2010. Additionally, a manual search in the major anatomy, dental implant, periodontal and oral surgery journals and books were performed. The publications there selected by including clinical, human anatomy and physiology studies.

Results

In total 136 literature sources were obtained and reviewed. Aetiological factors of inferior alveolar nerve injury, risk factors, mechanism, clinical sensory nerve examination methods, clinical symptoms and treatment were discussed. Guidelines were created to illustrate the methods used to prevent and manage inferior alveolar nerve injury before or after dental implant placement.

Conclusions

The damage of inferior alveolar nerve during the dental implant placement can be a serious complication. Clinician should recognise and exclude aetiological factors leading to nerve injury. Proper presurgery planning, timely diagnosis and treatment are the key to avoid nerve sensory disturbances management.

Neuropathic pain resulting from implant placement: case report and diagnostic conclusions

Temporary or persisting dysesthesia of the nervus alveolaris inferior has often been described as a complication of implant surgery of the lower mandible. In most cases, lesion of the nerve results in anaesthesia of the innervated region, a symptom clearly indicative of correct diagnosis. In our case report, however, a minor perforation of the roof of the mandibular canal during implant placement apparently provoked discrete irritation of the nerve, resulting in persistent neuropathic pain without concomitant hypesthesia or dysesthesia. Because the canal could not be detected in conventional dental radiographs, this uncharacteristic situation made correct diagnosis difficult and led to unnecessary surgical procedures including extraction of adjacent teeth. Medical imaging [computed tomography (CT)] finally revealed the close proximity of the apex of the implant and the bony structure of the mandibular canal. The effect on the nervus alveolaris inferior was also demonstrated using an innovative high-resolution dental magnetic-resonance-imaging technique reflecting vascular reactions of the neurovascular bundle after potentially damaging surgical intervention. After removal of the causative implant, the pain gradually faded over a period of a year.

Use of topical medication in orofacial neuropathic pain: a retrospective study

OBJECTIVE

The objective of this study was to evaluate the effect of topical medications as a single treatment or in combination with systemic medications in the treatment of orofacial neuropathic pain conditions.

STUDY DESIGN

A retrospective chart review of 39 patients treated for orofacial neuropathic pain at the Orofacial Pain Clinic in the New Jersey Dental School was performed. In line with the treatment selection, the subjects were divided into 3 groups: topical medications only (n = 12), systemic medications only (n = 10), and a combination of both (n = 17).

RESULTS

The starting pain level as expressed in pain Visual Analog Scale for the 3 groups was significantly different. The combined treatment group baseline pain level (7.5 +/- 0.403 SEM; P = .0015) and the systemic treatment only group pain level (8.6 +/- 0.611 SEM; P = .0375) was significantly elevated compared to the topical only group (6.1 +/- 0.716 SEM; P = .1057). Following treatment, pain level was significantly reduced in all 3 groups. The combined group had the highest pain relief (52.0 +/- 6.676 SEM % reduction; P < .0001) followed by the systemic-only group (40.6 +/- 9.727 SEM % reduction; P = .0029) and the topicals-only group (40.9 +/- 10.775 SEM% reduction; P = .0048). The time taken for the topical treatment only to act was significantly shorter (3 weeks +/- 0.479 SEM; P = .0015) when compared with the systemic-only (4 weeks +/- 0.772 SEM; P = .3629) and the combined group (5.5 weeks +/- 0.912 SEM; P = .1738).

CONCLUSION

Topical medication as single treatment or in combination with systemic medications can reduce orofacial neuropathic pain severity. Further prospective research should be performed to validate this treatment option.

The prevalence of trigeminal neuritis with TMD

Subjects with temporomandibular joint disorder (TMD) occasionally present with additional orofacial pain complaints. These can arise from dysfunction in teeth, bones, ligaments, tendons, nerves, and other structures. In this retrospective study, a group of 501 consecutive subjects with TMD complaints were evaluated for the presence of trigeminal neuritis. Very little information on the prevalence of this condition concomitant with TMDs exists in the literature. The existence of trigeminal neuritis was determined by the presence of pain when palpating trigeminal peripheral nerve branches exiting the supraorbital, infraorbital, and mental foramina in addition to the supratrochlear nerve. Each subject in this study had the involved nerves blocked with local anesthesia injections or lidocaine iontophoresis to assist in confirming the source of pain. Sixty subjects with TMD were found to have trigeminal neuritis. Early recognition of this disorder is important because treatment is usually more successful in the acute peripheral state.

Management of patients with trigeminal nerve injuries after mandibular implant placement

BACKGROUND

Placement of mandibular endosseous implants can result in damage to the lingual nerve, the inferior alveolar nerve or both nerves. All dentists who place mandibular implants should be aware of the appropriate early management of these injuries, as well as the appropriate time to refer patients with these injuries to a microneurosurgeon.

OVERVIEW

The lingual nerve is less likely to undergo spontaneous regeneration than is the inferior alveolar nerve, which is protected within the inferior alveolar canal. Since the inferior alveolar canal can be seen on most panoramic radiographs and on all high-quality computed tomographic scans, it is easier to avoid damage to the inferior nerve than to the lingual nerve, which is not visualized on radiographs and whose relationship to the posterior portion of the mandible varies from person to person.

RESULTS

The authors reviewed one study that showed that lingual nerve repair helped 90 percent of patients. A second study found that patients who underwent lingual nerve repair reported a mean score of 7 on a scale from 0 to 10 in regard to the postoperative return of nerve function. Several other studies reported favorable patient responses to inferior alveolar nerve repair.

CONCLUSIONS AND CLINICAL IMPLICATIONS

These results reinforce the need for early referral and intervention when inferior alveolar nerve injuries occur. Failure to refer patients with trigeminal nerve injury before distal nerve degeneration develops prevents minimization of the injury through microneurosurgical repair.

Incidence of chronic neuropathic pain subsequent to surgical removal of impacted third molars

To determine the incidence of atypical odontalgia/chronic neuropathic pain subsequent to surgical removal of impacted third molars, a telephone survey and a clinical investigation were carried out. Patients operated on for impacted mandibular third molars during 1994 96 in the Oral Surgery Clinic. School of Dentistry, University of Bergen, Bergen, Norway, were contacted by telephone. Answers were obtained from 1035 (71%) out of a total of 1458 operated patients. Median observation time was 5 years 9 months, ranging from 4 years 5 months to 6 years 9 months. All except 23 (2.2%) patients stated that they had no long-term symptoms or problems from the surgical site, jaw, or face after the third molar removal. These 23 patients were all examined clinically and radiologically, and symptoms and findings were evaluated. Seventeen patients had TMJ dysfunction: primarily pain of muscular and joint origin. Three patients had a periodontal problem associated with the adjacent second molar, with deep bony pockets and recurrent periodontal infection while two had chronic pulpitis of a second molar. One patient reported a temporary maxillary pain after removal of an ipsilateral mandibular third molar. None of the patients met the criteria for a diagnosis of atypical odontalgia/neuropathic pain. A 95% confidence interval of 0-0.38% of incidence rate of postoperative neuropathic pain was calculated. It is concluded that atypical odontalgia/ chronic neuropathic pain subsequent to surgical third molar removal is rare.

Orofacial sensory changes and temporomandibular dysfunction

Orofacial sensory changes are uncommon complaints that can coexist with temporomandibular dysfunction (TMD). The location, character, and intensity vary greatly with each individual and symptom fluctuation is not unusual for any patient. The etiology of orofacial sensory changes may be related to either local or systemic factors. Several investigators have reported that muscle entrapment of branches of the third division of the trigeminal nerve may result in orofacial sensory disruption. Different theories have been suggested to illustrate how TMD and trauma might be associated with these neurological changes. Additionally, several mechanisms exist to explain how muscle spasms may be responsible for nerve compression in individuals with normal anatomy and in those with anatomical variations. In this study, thirty subjects from a group of 282 TMD patients were found to have coexisting orofacial sensory disturbances and TMD. Subjects presenting with any neurological complaints should alert the clinician to the possibility that these symptoms may be the early clinical signs of serious disease.

Topical medications for orofacial neuropathic pain: a review

BACKGROUND

The authors discuss the local pharmacotherapy for chronic orofacial neuropathic pain disorders such as neuropathies, neuromas and neuralgias.

METHODS

The authors conducted a systematic literature review on this topic. The focus of the review involved the two most commonly applied medications for neuropathic disorders--local anesthetics and capsaicin. Other compounds such as nonsteroidal anti-inflammatory drugs, sympathomimetic agents, anticonvulsants and N-methyl-D-aspartate receptor antagonists also were reviewed. The medication delivery and retention methods appropriate for oral and perioral disease and pain control are described in this article.

RESULTS

There are an ever-increasing number of agents that can be used to help patients with neuropathic-based oral and perioral pain problems. Moreover, a clear advancement in the delivery of these medications is the development of a vehicle-carrier agent (pluronic lecithin organogel) that can penetrate the mucosa and cutaneous tissues and carry the active medication with it to the treatment site. The major caveat underlying these treatment strategies is that except for patient testimony and a few studies, there are limited empirical data on the efficacy of most of these new formulations, and additional research is clearly needed.

CONCLUSIONS

Because of their rapid onset and low side-effect profile, topical medications offer a distinct advantage over systemic administration for those orofacial disorders that are regional, near the surface and chronic and that demonstrate some response such as pain relief to topical or subcutaneous anesthetics.

CLINICAL IMPLICATIONS

Practicing dentists now have some new tools they can use to help manage patients who have a chronic nerve pain disorder in and around the mouth.

Trigeminal neuropathic pain: pathophysiological mechanisms examined by quantitative assessment of abnormal pain and sensory perception

OBJECTIVE

This study was undertaken to examine the pathophysiological characteristics of trigeminal neuropathic pain.

METHODS

The study included 23 consecutive patients with trigeminal neuropathic pain (15 patients with pain after nerve injury and 8 patients with pain of spontaneous origin). For each patient, quantitative examination of sensory and pain perception was performed in the painful facial skin area, and results were compared with the findings for the contralateral nonpainful facial skin area.

RESULTS

In the painful facial skin area of patients with neuropathic pain after nerve injury, we demonstrated increased temperature and tactile thresholds, as well as abnormal temporal summation of pain (i.e., repetitive nonpainful skin stimulation produced an abnormal progressive increase of pain intensity, with abnormal radiation of pain and aftersensation). In the painful skin area of patients with pain of spontaneous origin, temperature and tactile thresholds were not increased, but heat pain and cold pain thresholds were significantly reduced, indicating heat and cold hyperalgesia. The characteristics of temporal summation of pain were not significantly altered in the painful facial skin area in this group of patients.

CONCLUSION

This clinical study provides evidence that the pathophysiological mechanisms of trigeminal neuropathic pain after nerve injury involve impaired function of both small unmyelinated fibers and large myelinated fibers. An explanation for the finding of abnormal temporal summation of pain may involve hyperexcitability of central wide-dynamic range neurons. The results suggest that other mechanisms are involved in trigeminal neuropathic pain of spontaneous origin. Reduced heat and cold pain thresholds indicate heat and cold hyperalgesia, which possibly may be explained by sensitization of peripheral C nociceptors.