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

Delayed repair of the facial nerve and its negative impacts on nerve and muscle regeneration

Background

In this experimental protocol, we evaluated the immediate and delayed repair of the buccal branch of the facial nerve (BBFN) with heterologous fibrin biopolymer (HFB) as a coaptation medium and the use of photobiomodulation (PBM), performing functional and histomorphometric analysis of the BBFN and perioral muscles.

Methods

Twenty-eight rats were divided into eight groups using the BBFN bilaterally (the left nerve was used for PBM), namely: G1 - control group, right BBFN (without injury); G2 - control group, left BBFN (without injury + PBM); G3 - Denervated right BBFN (neurotmesis); G4 - Denervated left BBFN (neurotmesis + PBM); G5 - Immediate repair of right BBFN (neurotmesis + HFB); G6 - Immediate repair of left BBFN (neurotmesis + HFB + PBM); G7 - Delayed repair of right BBFN (neurotmesis + HFB); G8 - Delayed repair of left BBFN (neurotmesis + HFB + PBM). Delayed repair occurred after two weeks of denervation. All animals were sacrificed after six weeks postoperatively.

Results

In the parameters of the BBFN, we observed inferior results in the groups with delayed repair, in relation to the groups with immediate repair, with a significant difference (p < 0.05) in the diameter of the nerve fiber, the axon, and the thickness of the myelin sheath of the group with immediate repair with PBM compared to the other experimental groups. In measuring the muscle fiber area, groups G7 (826.4 ± 69.90) and G8 (836.7 ± 96.44) were similar to G5 (882.8 ± 70.51). In the functional analysis, the G7 (4.10 ± 0.07) and G8 (4.12 ± 0.08) groups presented normal parameters.

Conclusion

We demonstrated that delayed repair of BBFN is possible with HFB, but with worse results compared to immediate repair, and that PBM has a positive influence on nerve regeneration results in immediate repair.

Effectiveness of concentrated growth factor and laser therapy on wound healing, inferior alveolar nerve injury and periodontal bone defects post-mandibular impacted wisdom tooth extraction: A randomized clinical trial

The extraction of wisdom teeth with mandibular impact frequently results in complications including damage to the inferior alveolar nerve (IAN) and malformations of the bone. The objective of this research endeavour was to assess the efficacy of low-level laser therapy and concentrated growth factor (CGF) in facilitating nerve recovery and wound healing in such instances. A total of thirty-one patients (mean age 27.52 ± 5.79 years) who presented with IAN injury after extraction were randomly assigned to one of three groups: control group (which received oral mecobalamin), CGF group (which received CGF gel applied to the extraction sockets) and laser group (which received low-level lasers (808 nm, 30 mW, 10 J/cm2 )) at the extraction site. Patients' recovery from IAN paresthesia was evaluated seven times over the course of 14 days utilizing visual analogue scale (VAS) and the pinprick test (PP). At multiple intervals following surgery, periodontal probing and bone level measurements were utilized to assess the recovery of both soft and hard tissues. The findings revealed that, compared with the control group, both the CGF and laser treatment groups exhibited a markedly greater improvement in VAS scores and wound healing of soft tissues, as well as in PP results (p < 0.001), indicating enhanced wound healing processes. Despite these improvements, there was no significant difference in wound healing outcomes between the CGF and laser groups. Notably, the CGF group showed a statistically significant improvement in healing bone defects at 30 and 90 days post-treatment compared with the control group (p = 0.003 and p = 0.004, respectively), underscoring its effectiveness in bone healing as a critical aspect of the overall wound healing process. However, in terms of other wound healing comparisons, no significant differences were observed. CGF and laser therapy significantly enhanced the healing of wounds, including soft tissue and bone recovery, in addition to accelerating the recovery of IAN injuries following mandibular wisdom tooth extraction. Although both treatments were equally effective in nerve recovery, CGF notably excelled in promoting bone healing, suggesting its pivotal role in comprehensive wound healing. This highlights that both CGF and laser therapy are viable options for not only nerve recovery but also for overall wound healing in such dental procedures.

Morphofunctional Improvement of the Facial Nerve and Muscles with Repair Using Heterologous Fibrin Biopolymer and Photobiomodulation

Peripheral nerve injuries impair the patient's functional capacity, including those occurring in the facial nerve, which require effective medical treatment. Thus, we investigated the use of heterologous fibrin biopolymer (HFB) in the repair of the buccal branch of the facial nerve (BBFN) associated with photobiomodulation (PBM), using a low-level laser (LLLT), analyzing the effects on axons, muscles facials, and functional recovery. This experimental study used twenty-one rats randomly divided into three groups of seven animals, using the BBFN bilaterally (the left nerve was used for LLLT): Control group-normal and laser (CGn and CGl); Denervated group-normal and laser (DGn and DGl); Experimental Repair Group-normal and laser (ERGn and ERGl). The photobiomodulation protocol began in the immediate postoperative period and continued for 5 weeks with a weekly application. After 6 weeks of the experiment, the BBFN and the perioral muscles were collected. A significant difference (p < 0.05) was observed in nerve fiber diameter (7.10 ± 0.25 µm and 8.00 ± 0.36 µm, respectively) and axon diameter (3.31 ± 0.19 µm and 4.07 ± 0.27 µm, respectively) between ERGn and ERGl. In the area of muscle fibers, ERGl was similar to GC. In the functional analysis, the ERGn and the ERGI (4.38 ± 0.10) and the ERGI (4.56 ± 0.11) showed parameters of normality. We show that HFB and PBM had positive effects on the morphological and functional stimulation of the buccal branch of the facial nerve, being an alternative and favorable for the regeneration of severe injuries.

Effect of Photobiomodulation Therapy on Differentiation of Mesenchymal Stem Cells Derived from Impacted Third Molar Tooth into Neuron-like Cells

Peripheral nerve damages are among the most important consequences of dental and maxillofacial procedures. Tissue engineering using mesenchymal stem cells (MSCs) is a promising method to manage such injuries. Moreover, photobiomodulation therapy (PBMT) can enhance this treatment. The present study aimed to investigate the effect of PBMT on differentiation of MSCs derived from dental follicle (DF) into neurons. MSCs were isolated from an impacted tooth follicle by digestion method. The stem cells were cultured, and differentiated into neurons. The cells received two sessions of PBMT with 810 or 980nm diode laser (100 mW, 4 J/cm² ) in either DMEM or neural inductive medium . Phenotypic characterization of the cells was determined using Flow cytometry. In addition, β-tubulin and MAP2 genes expression level changes were analyzed using RT-PCR and western blot technique. After 14 days, Flow cytometry analysis confirmed the mesenchymal nature of cells. RT-PCR and western blot affirmed the expression of β-tubulin and MAP2 genes and proteins, respectively. PBMT with both wavelengths significantly increased β-tubulin and MAP2 expression in neural inductive medium with highest expression mean in 980-nm group. PBMT with 810 and 980-nm lasers could be a promising adjunctive method in differentiation of DF-originated MSCs into neural cells.