Dentoalveolar Nerve Injury

Effects of NGF and Photobiomodulation Therapy on Crush Nerve Injury and Fracture Healing: A Stereological and Histopathological Study in an Animal Model

Study Design

A stereological and histopathological study in an animal model.

Objective

This study explores the effects of the nerve growth factor and photobiomodulation therapy on the damaged nerve tissue and fracture healing.

Methods

A total of 24 rabbits were divided into 4 groups: control group (n = 5), nerve growth factor (NGF) group (n = 7), photobiomodulation (PBMT) group (n = 6), and nerve growth factor and photobiomodulation therapy (NGF+PBMT) group (n = 6). The vertical fracture was performed between the mental foramen and the first premolar, and the mental nerve was crushed for 30 seconds with a standard serrated clamp with a force of approximately 50 N in all groups. The control group received an isotonic solution (.02 mL, .09% NaCl) to the operation site locally. The NGF group received 1 μg human NGF-β/.9% .2 mL NaCl solution for 7 days locally. The PBMT group received PBMT treatment (GaAlAs laser, 810 nm, .3 W, 18 J/cm2) every 48 hours for 14 sessions following the surgery. The NGF+PBMT group received both NGF and PBMT treatment as described above. After 28 days, the bone tissues and mental nerves from all groups were harvested and histologically and stereologically analyzed.

Results

According to the stereological results, the volume of the new vessel and the volume of the new bone were significantly higher in the PBMT group than in other groups (P < .001). According to the histopathological examinations, higher myelinated axons were observed in experimental groups than in the control group.

Conclusions

As a result, PBMT has beneficial effects on bone regeneration. Based on the light microscopic evaluation, more regenerated axon populations were observed in the NGF group than in the PBMT and PBMT + NGF groups in terms of myelinated axon content.

Morphological Studies to Identify the Nasopalatine and Inferior Alveolar Nerve Using a Special Head and Neck MRI Coil

OBJECTIVES

Procedures in oral and maxillofacial surgery bear a high risk of nerve damage. Three-dimensional imaging techniques can optimize surgical planning and help to spare nerves. The aim of this study was to investigate the diagnostic value of a 1.5 T magnetic resonance imaging (MRI) scanner with a dedicated dental signal amplification coil for the assessment of nerves in the oral cavity as compared with cone beam computed tomography (CBCT).

METHODS

Based on 6 predefined criteria, the assessability of the inferior alveolar and nasopalatine nerves in CBCT and MRI with a dedicated 4-channel dental coil were compared in 24 patients.

RESULTS

Compared with CBCT, MRI with the dental coil showed significantly better evaluability of the inferior alveolar nerve in the sagittal and axial plane and the nasopalatine nerve in the axial plane. In the sagittal plane; however, the assessability of the nasopalatine nerve was significantly better in CBCT as compared with MRI. Yet, pertaining to overall assessability, no significant differences between modalities were found.

CONCLUSIONS

In this pilot study, it can be reported that 1.5- T MRI with a dedicated dental coil is at least equivalent, if not superior, to CBCT in imaging nerve structures of the stomatognathic system.

CLINICAL RELEVANCE

Preoperative, 3-dimensional images are known to simplify and refine the planning and execution of operations in maxillofacial surgery. In contrast to computed tomography and CBCT, MRI does not cause radiation exposure while enabling visualization of all relevant hard and soft tissues and, therefore, holds an advantage over well-established techniques.

Photobiomodulation Therapy for the Management of Patients With Inferior Alveolar Neurosensory Disturbance Associated With Oral Surgical Procedures: An Interventional Case Series Study

Introduction: Inferior alveolar nerve (IAN) injury is a serious complication during intraoral surgeries. We aimed to evaluate the outcome of photobiomodulation (PBM) therapy in patients with IAN injury associated with third molar or implant procedures. Methods: Eight patients with an alteration of sensory function of the IAN after third molar or implant surgeries were enrolled in this case series study. The patients received 10 sessions of PBM therapy (810 nm diode laser, 200 mW, 10 J/cm² per point, three times a week). Pinprick (PP) and visual analogue scale (VAS) neurosensory tests were recorded at each treatment session and 14 days after the last treatment. The association between explanatory variables and the outcome of interest was analyzed using generalized estimating equations. Results: The median percentage change of outcomes from the first to the last visit was as follows: VAS score: +125.00% (range: 50.00 to 166.67); PP score: +350% (range: 150 to 800). The duration of paresthesia was inversely correlated with changes in VAS and PP scores. No significant association was found between patients' gender or age and changes in VAS and PP scores. Conclusion: Considering the limitations of this study, PBM with the parameters used in this study presented positive effects on neurosensory recovery in patients suffering from IAN injury associated with routine intraoral procedures. Patients with shorter duration of paresthesia tended to respond more favorably to PBM therapy.

Coronectomy of mandibular third molars: a systematic literature review and case studies

BACKGROUND

Extraction of mandibular third molars (M3M) close to the inferior alveolar nerve (IAN) has a higher risk of neurological disturbance. This review aims to evaluate the evidence supporting the use of the coronectomy technique compared to complete extraction for such M3Ms. Case studies by a specialist oral and maxillofacial surgeon are included to illustrate clinical practice.

METHODS

Three databases (Cochrane Library, Embase, PubMed) were searched (November 2020). Additional articles were sought by hand searching the reference list of included articles. All studies published in English comparing outcomes of coronectomy with complete extraction with at least 50 subjects and 6 months follow-up were included.

RESULTS

Of the six included studies, five reported a lower rate of IAN disturbance after coronectomy compared with complete extraction. There were no reported cases of lingual nerve disturbance. Other outcomes of coronectomy such as pain, infection, alveolar osteitis were either similar or lower compared to complete extraction. There were high rates of root migration but low rates of exposure and reoperation. Follow-up protocols varied considerably.

CONCLUSIONS

There is medium quality evidence to support the option of coronectomy for high risk M3M cases. Further studies to develop follow-up protocols to assist general dental practice is warranted.

Coronectomy of impacted mandibular third molars: A meta-analysis and systematic review of the literature

BACKGROUND

Coronectomy is an alternative to complete removal of an impacted mandibular third molar. Most authors have recommended coronectomy to prevent damage to the inferior alveolar nerve during surgical extraction of lower third molars. The present study offers a systematic review and metaanalysis of the coronectomy technique.

MATERIAL AND METHODS

A systematic review and meta-analysis was performed based on a PubMed and Cochrane databases search for articles published from 2014 and involving coronectomy of mandibular third molars located near the inferior alveolar nerve canal, with a minimum of 10 cases and a minimum follow-up period of 6 months. After application of the inclusion and exclusion criteria, a total of 12 articles were included in the study.

RESULTS AND DISCUSSION

Coronectomy results in significantly lesser loss of sensitivity of the inferior alveolar nerve and prevents the occurrence of dry socket. No statistically significant differences were observed in the incidence of pain and infection between coronectomy and complete surgical extraction. After coronectomy, the remaining tooth fragment migrates an average of 2 mm within two years.

CONCLUSIONS

Coronectomy is indicated when the mandibular third molar is in contact with the inferior alveolar nerve and complete removal of the tooth may cause nerve damage.

Use of Fibrin Glue as an Adjunct in the Repair of Lingual Nerve Injury: Case Report

This report describes a case of lingual nerve injury repair using a novel technique in which Tisseel fibrin glue was used to stabilize an Axoguard nerve conduit placed around the site of primary neurorrhaphy to decrease the number of sutures required for stabilization. Five months postoperatively, the patient subjectively had increased sensation and improved taste in the left lingual nerve distribution. At neurosensory examination, the patient exhibited functional neurosensory recovery (S3+ on the Medical Research Council Scale).