Injury to the inferior alveolar nerve (IAN) arises from factors inherent to its complex anatomy and proximity to dental structures. Among its causes are a wide range of procedures performed within its innervation territory, including local anaesthetic infiltration, endodontic treatment, and surgical interventions [1-4]. Among the latter, mandibular third molar extraction and dental implant placement in the posterior mandibular region, together with mandibular sagittal osteotomies, represent the main aetiological factors of nerve injury, with incidence rates ranging from 0.2 to 7.1% in third molar extraction and 1.7 to 43.5% in implant surgery [5-9].

The symptomatology resulting from nerve injury depends on its nature, severity, and the type of damage caused to the nerve fibres (neurapraxia, axonotmesis, or neurotmesis) [10,11] and may significantly impair patients’ quality of life due to a wide range of sensory symptoms, including paraesthesia, dysesthesia, anaesthesia, and, in some cases, neuropathic pain.

In most patients, sensory disturbance is transient and may resolve spontaneously, occurring in 1.2 to 13.4% of cases following third molar extraction and up to 24% following implant placement. When sensory alteration persists beyond six months post-treatment, it is considered permanent, a complication reported in up to 11% of implant surgeries in the posterior mandible according to some studies [12,13].

For proper diagnosis and monitoring, a series of tests have been described to determine the degree of nerve injury and prognosis, as well as to select appropriate treatment and assess recovery. These so-called neurosensory tests are divided into two major categories: mechanoreceptive and nociceptive. Both evaluate the peripheral afferent A-delta (Aδ) and C fibres, which are small-diameter, slow-conducting fibres responsible for tactile, thermal, and pain sensitivity [14]. In addition to objective tests, subjective tools such as the Visual Analog Scale (VAS) are used to assess patient-reported symptoms.

Therapeutic options for these injuries are diverse and include pharmacological treatment (corticosteroids, NSAIDs, B and C vitamin complexes, nucleotides) [3], local physiotherapy, electrical stimulation, acupuncture, laser therapy, and surgical management (microsuturing or nerve grafting) when complete nerve transection is present [15-18].

Low-level laser therapy (LLLT), also known as photobiomodulation (PBM), was first described by Rochkind in 1978 [19]. It uses specific light wavelengths, typically within the infrared range, without producing thermal effects. Its use has been proposed as an alternative therapy, showing promising results in the recovery of nerve injuries due to its demonstrated capacity to promote regeneration of damaged neural tissue [20].

The described mechanisms of action of PBM include the reduction of inflammation and pain, as well as the promotion of neuronal repair [11-23]. Several studies suggest these effects are partially due to the modulation of inflammatory mediators, such as decreased tumour necrosis factor-alpha (TNF-α) and interleukin-1 (IL-1) [24], increased trophic factors, and stimulation of collateral reinnervation [25], as well as mitochondrial activation to boost adenosine triphosphate (ATP) production. PBM has also been shown to enhance the synthesis of growth factors [26], thereby contributing to nerve fibre regeneration, increased myelinated fibre count, and subsequent improvement in nerve function.

Compared to conventional pharmacological therapies, PBM offers several advantages in the treatment of nerve injuries, including the absence of side effects, its non-invasive nature, and high levels of patient satisfaction. These factors make PBM an attractive alternative for resolving sensory disturbances caused by third molar extractions or dental implant placement. The majority of the existing literature has focused on PBM’s efficacy in sensory alterations secondary to mandibular sagittal osteotomies [27-30], whereas fewer studies have explored its use for injuries arising from third molar extractions and posterior dental implants [31,32]. Therefore, the primary goal of present study is to evaluate if photobiomodulation therapy is effective in the treatment of inferior alveolar nerve injuries after third molar extraction or posterior mandible implant surgery. The secondary goal is to determine what doses and timing are effective for the treatment.

Protocol and registration

A systematic literature review was conducted following the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [33], with the objective of evaluating the effectiveness of PBM therapy in treating IAN injuries resulting from mandibular third molar extraction or dental implant placement in the posterior mandible.

The review protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO), under registration number CRD42025621162. The protocol can be accessed at:

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42025621162

Focus question

The research question was systematically formulated following the Patient, Intervention, Comparison, Outcome, and Study Design (PICOS) framework (Table 1) [34].

The PICO model for this systematic review was as follows:

The focus question: “Is PBM therapy effective in neurosensory recovery of IAN damage after third molar extraction or implant surgery?”

Information sources

An electronic literature search was conducted in the databases MEDLINE (PubMed), Scopus, Web of Science, and the Cochrane Library, limited to English or Spanish publications from January 1, 1993 to September 30, 2024.

Search

A comprehensive electronic search was conducted in accordance with the PRISMA guidelines to identify relevant studies. The search terms used were: “Low Level Laser Therapy” OR “Low Level Light Therapy” OR “Light Therapies” OR “Photobiomodulation” OR “LLLT” OR “Laser Therapy Low Level” OR “Low Power Laser Therapy” OR “Laser Phototherapy” OR “Laser Biostimulation” OR “Biostimulation” OR “Low Power Laser Irradiation” OR “diode laser” AND “Inferior Alveolar Nerve” OR “Mandibular Nerve” AND “Injury” OR “Damage” OR “Paraesthesia” OR “Neurosensory Disturbance” AND “Third Molar Extraction” OR “Wisdom Tooth Extraction” OR “Implant Surgery” OR “Dental Implants”.

Additionally, the reference lists of included articles, as well as relevant narrative and systematic reviews, were manually screened.

Selection of studies

After duplicate removal, two reviewers (A.B. and J.S.) independently screened the records obtained from the systematic search. In the initial phase, titles and abstracts were reviewed to exclude irrelevant articles. Subsequently, full texts of selected studies were assessed to determine eligibility for inclusion. Disagreements were resolved through discussion and consensus, with the involvement of a third reviewer (C.M.) when necessary. To ensure inter-rater reliability in the screening process, a calibration exercise was conducted using a random sample comprising 10% of the identified publications.

Types of publications

Human studies published in Spanish or English language were included in the review. Letters to the editor, editorials, doctoral theses, and conference abstracts were excluded.

Types of studies

The review included clinical trials, availability of at least one experimental and/or a control group, cases series and retrospective studies evaluating the effectivity of PBM after IAN injury.

Types of participants

Patients with IAN injury secondary to implant treatment or surgical extraction of mandibular third molars.

Inclusion and exclusion criteria

Inclusion criteria

Exclusion criteria

Sequential search strategy

In accordance with PRISMA guidelines [33], titles of all records identified through the initial search were screened to remove irrelevant studies. Thereafter, abstracts were assessed to exclude articles that did not meet the eligibility criteria. Full-text articles of potentially relevant studies were then retrieved and evaluated in detail to confirm their inclusion in the final review.

Data extraction

In alignment with the objectives and specific tasks outlined for this review, data were independently extracted from the included studies in the form of relevant variables. This process was directly guided by the review’s aims and thematic focus, as detailed below. In cases where essential information was missing, the corresponding authors were contacted via email to obtain the necessary data. Any disagreements were resolved by discussion; if unresolved, a third reviewer was consulted.

Data items

From each study, the following parameters were extracted when available using a standardized table: first author and publication year, study design, sample size, gender, age, aetiology of nerve injury, time elapsed between injury and treatment, type of laser used, wavelength and emission mode, energy per point and fluence, power, duration of laser application, number of sessions, types of sensory tests, follow-up duration, and reported outcomes.

Risk of bias within studies

The two principal reviewers (A.B. and J.S.) assessed the methodological quality and risk of bias of the included studies. Disagreements were resolved by consensus, or by consultation with a third reviewer (C.M.). Specific assessment tools were applied according to the study design.

For RCTs, the Cochrane Risk of Bias Tool for RCTs was used [35], which evaluates six domains: selection bias (random sequence generation, allocation concealment), performance bias (blinding of participants and personnel), detection bias (blinding of outcome assessment), attrition bias (incomplete outcome data), reporting bias (selective outcome reporting), and other potential sources of bias. “Low risk”, “high risk”, “unclear” was given to each criterion.

For case series, a quality assessment tool based on the modified Delphi technique was employed [36]. Studies with > 70% affirmative responses were considered of acceptable quality and low risk of bias.

For observational studies, the National Institutes of Health (NIH) Quality Assessment Tool for Before-After (Pre-Post) Studies With No Control Group was applied [37].

Statistical analysis

Mendeley^® (Elsevier; London, UK) reference manager software was used for article management. Inter-rater agreement between the two reviewers during the abstract and study selection process was quantified using Cohen’s kappa coefficient (κ).

Statistical analysis was performed using IBM SPSS^®. Statistics software version 30.0 (IBM Corp.; Armonk, New York, USA). P-value was considered statistically significant at P < 0.05.

The performance of a meta-analysis was not feasible, since the studies included in this review exhibited substantial heterogeneity in their PBM protocols. Specifically, the investigations differed with regard to the wavelength employed, the anatomical site of application, the number and frequency of treatment sessions, the overall duration of therapy, and the time point at which photobiomodulation was initiated. Such variability precluded the possibility of pooling data in a statistically meaningful manner.

Study selection

The initial databases search revealed 3,376 records, of which 2,399 duplicates were excluded (Figure 1). A total of 977 titles and abstracts were screened, leading to the exclusion of 966 articles because they were not in English or Spanish and/or did not address the aetiology of the nerve injury. Eleven full-text articles were retrieved for comprehensive analysis [23,31,32,38-45], of which one was excluded [31].

Finally, 10 studies [23,32,38-45] were included in this systematic review. Among these, four were RCTs [23,38,39,45], five were case series [32,40-42,44], and one was a retrospective observational study [43]. All of them evaluated the effect of LLLT on IAN injuries-five following mandibular third molar extraction and five following extractions of third molars or placement of implants in the posterior mandibular region.

The level of agreement between the reviewers (A.B. and J.S.) on title and abstract selection was assessed by calculating Cohen’s kappa coefficient (κ), showing a value of 0.87, which indicates strong agreement.

Exclusion of studies

After comprehensive analysis, one full-text article was excluded for being a case report [31].

Risk of bias within studies

The findings are summarized in the methodological quality and risk of bias tables (Table 2, 3 and 4). Only one [39] of the four RCTs included [23,38,39,45] was rated as low risk of bias across all domains (Table 2).

Of the five case series analysed [32,40-42,44], four [32,40-42] were assessed as low risk of bias with 77.8% and 72.2% affirmative responses on the 18-item Delphi-based checklist (Table 3).

The observational study by de Oliveira et al. [43] met 7 out of 12 quality assessment items (> 50%) (Table 4).

Study characteristics

The number of patients included in the studies [23,32,38-45] ranged from 4 to 125 (Table 5). Only studies in which the aetiology of the nerve injury was mandibular third molar extraction and/or posterior dental implant placement were considered.

In most studies, the control groups received either inactive laser (placebo) or no treatment, whereas only one study employed mecobalamin (vitamin B12) as an alternative therapy to laser [23].

Reported sensory disturbances among patients included paraesthesia, dysaesthesia, hypaesthesia, anaesthesia, and hyperaesthesia. One study did not specify the type of sensory alteration [38].

The time between nerve injury and initiation of PBM therapy varied from 48 hours [23] to 7 years [44] (Table 6). Four studies [32,42,43,45] stratified samples according to this time interval. Two studies reported significant differences favouring early treatment [43,45], while the other two found no timing-dependent effects [32,42].

Sensory recovery onset was noted between the sixth and eleventh sessions in two studies [32,39]. One study documented continued neurosensory improvement up to 24 months post-PBM therapy [44].

PBM therapy protocols

All studies utilized GaAlAs diode lasers with wavelengths ranging between 808 and 830 nm, except for Pol et al. [32], who applied a combination of 904 nm (superpulsed mode) and 650 nm (continuous mode) (Table 6). The energy per point ranged from 2.8 to 123 J, while the energy density varied from 3 to 244.8 J/cm². The power output ranged from 5 to 400 mW in continuous mode.

In most studies, both intraoral and extraoral points were irradiated. The intraoral application predominantly followed the course of the IAN (from the mandibular foramen to the mental foramen), while adjacent extraoral sites such as the lip and chin were also irradiated, regardless of the lesion location. Only Qi et al. [23], applied the laser via the post-extraction socket within two days after third molar removal (Table 5). The number of PBM sessions varied from 7 to 20, with frequencies of 1 to 3 sessions per week. Although the follow-up period was not specified in most studies, the longest recorded duration was 24 months [44]. In some cases, follow-up ended upon completion of the last PBM session (Table 6).

Neurosensory assessment methods

Both objective and subjective tests were used to evaluate neurosensory recovery. Objective assessments included tactile discrimination, two-point discrimination, directional discrimination, thermal discrimination (most commonly used), and pinprick or mapping tests. All studies used the VAS as the subjective measure, in which significant improvements in favour of PBM were reported in most studies [23,32,39,40-44] (Table 6).

Results of individual studies

Qi et al. [23] conducted a clinical trial comparing PBM therapy to oral mecobalamin in patients with IAN injury secondary to third molar extraction. Twenty patients were included and divided into two groups of 10: one receiving PBM and the other mecobalamin orally. Recovery was evaluated using both objective and subjective tests. At one-month post-extraction, the PBM group had achieved full sensory recovery, whereas half of the control group still exhibited deficits. VAS scores were significantly better in the PBM group by days 6 to 7 of treatment (P < 0.05), while the placebo group showed slower improvement.

Pol et al. [32] compared the effects of PBM in patients with nerve injuries of less than and more than six months of evolution, stemming from various aetiologies. At the end of therapy, 54.2% to 83.3% of patients achieved complete sensory recovery. No significant differences were observed between groups in objective test scores (P = 0.7914), although subjective perception of recovery (VAS) was markedly higher in the early-treatment group (P = 0.034). Clinical improvement began to be noticeable after the sixth session (Table 6).

Khullar et al. [38] conducted a double-blind randomised clinical trial (RCT) evaluating PBM in patients with IAN injuries lasting more than six months, including cases related to third molar extraction. Semmes-Weinstein monofilaments and thermal discrimination tests were used. The PBM-treated group showed significant improvement in both tests (P = 0.01), while the control group exhibited no neurosensory changes (Table 5 and 6).

Yari et al. [39] conducted another RCT including 36 patients to evaluate IAN recovery following third molar extraction. Participants were divided into two groups: 18 received PBM and 18 received placebo. Sensory disturbances included hypoesthesia (n = 16), paraesthesia (n = 14), and dysesthesia (n = 8). Assessment involved objective tests (light touch, two-point, directional, and thermal discrimination) and the VAS. After 11 days, the PBM group showed significantly superior recovery in most tests (P < 0.05), with effects persisting for up to 9 months. Thermal discrimination was the only test without statistically significant differences (P > 0.05), although improvement was observed in the PBM group (Table 5 and 6).

Ozen et al. [40] evaluated the effectiveness of PBM in four patients with IAN injury persisting for more than one year after third molar extraction. Reported neurosensory disturbances included dysesthesia, hypoesthesia, and paraesthesia. After 20 PBM sessions, all patients exhibited improvement in both objective and VAS assessments (P = 0.01 and P = 0.02 respectively) (Table 5 and Table 6).

Hakimiha et al. [41] conducted a case series including eight patients with paraesthesia in the lip and/or chin: six following third molar extraction and two after implant placement. Pinprick testing and the VAS were used to assess recovery. After 35 days, subjective improvements of 125% and objective improvements of 350% were reported (P < 0.001), with no significant differences according to age (P < 0.06) or gender (P < 0.75) (Table 5 and 6).

Bozkaya et al. [42] included 50 patients with nerve injuries of varying aetiologies, most related to third molar extraction. Statistically significant improvements were found in both VAS and objective neurosensory test outcomes in favour of PBM (P = 0.0). No significant differences were observed between groups based on age (P = 0.4), gender (P = 0.7), paraesthesia duration (P = 0.7), aetiology (P = 0.9), or affected location (P = 0.5) (Table 5 and 6).

In the observational study by de Oliveira et al. [43], over 80% of the 125 patients treated with PBM showed recovery classified as reasonable, good, or excellent, regardless of age, sex, or aetiology of the nerve injury. VAS was statistically significant (P < 0.05) (Table 5 and 6).

Among the case series included, Midamba and Haanaes [44] evaluated the effects of GaAlAs laser in 15 patients with IAN injury of varying aetiologies, including 11 from third molar extractions, 1 from implant placement, and 3 from other causes. Of the six patients with complete anaesthesia for less than one year, five experienced significant improvement after 12 to 19 PBM sessions. Overall, patients with recent injuries (< 1 year) reported improvements of 40 to 100%, and those with chronic injuries (> 1 year) showed recovery rates of 40 to 90%. One patient showed no improvement initially but experienced delayed recovery in the following months. Treatment was administered three times per week over 2 to 8 weeks. Statistically significant at P < 0.05 (Table 5 and 6).

Miloro and Criddle [45] performed an RCT including 28 patients with IAN injury, 22 from third molar extraction, one from implant placement, and 5 from other causes. No statistically significant differences were observed between PBM and placebo groups (P = 0.66), regardless of the nerve type affected or time since injury. Nevertheless, 46.7% of patients in the PBM group improved in at least one parameter, compared to 38.5% in the placebo group (Table 5 and 6).

Synthesis of results

All included studies reported improvements in neurosensory function in at least one of the objective and/or subjective assessments after PBM treatment. None of the studies reported adverse effects related to laser therapy. Only one study [32] addressed patient satisfaction following treatment (Table 6).

Summary of evidence

Surgical extraction of mandibular third molars and the placement of mandibular dental implants, along with sagittal split osteotomies, represent the main surgical procedures associated with the risk of injury to the IAN, due to the proximity of this vital anatomical structure to the operative area.

The various sensory disturbances resulting from such injuries can significantly compromise patients’ quality of life, especially when they become permanent. Although some authors [46,47] suggest that treatment should not be initiated within the first three months due to the possibility of spontaneous recovery, a larger number advocate for early intervention to mitigate symptoms and enhance the chances of complete recovery [48].

Although no standardized treatment protocol has yet been established for IAN injuries, various therapeutic approaches have been proposed, including pharmacological therapy with anti-inflammatories, corticosteroids, and B-vitamin complexes, as well as physical therapy, acupuncture, and PBM [40]. In addition, the IANIDIS protocol has been proposed for IAN injuries associated with implant surgeries for diagnosis and treatment [49] but there is not still a scheduled protocol for IAN injuries treatment.

Treatment efficacy

With the exception of the randomized clinical trial by Miloro and Criddle [45], all studies included in this review reported both objective and subjective improvement in sensory recovery following PBM therapy.

These findings are consistent with those reported by other authors. Notably, Alharbi et al. [47], in their systematic review, evaluated the effect of LLLT on sensory recovery of IAN injuries. Three of the RCTs included in their review showed statistically significant results in favour of PBM, in both objective and subjective assessments [28,32,38]. Similarly, Mirzaei et al. [50] observed significant improvements in six out of the seven clinical trials evaluated [28,29,51-54]. Additionally, a Cochrane review by Coulthard et al. [55] included two RCTs comparing PBM to placebo, identifying positive effects on sensory recovery, though the findings were limited by high risk of bias due to heterogeneity among the studies.

Assessment of sensory improvement

Despite the lack of consensus on the optimal method to uniformly assess sensory improvement, most studies use both subjective and objective tests [23,32,40,43,45]. Among subjective tools, the VAS is considered the gold standard for assessing perceived sensory alteration. For objective tests, mechanoreceptive assessments are commonly used to evaluate the function of large myelinated fibres (A-α and A-β), while nociceptive tests assess small myelinated A-δ fibres and unmyelinated C fibres [56,57]. However, VAS scores may be influenced by the patient’s physical and psychological state, and may reflect changes such as paraesthesia that are not detectable with objective testing-highlighting the importance of combining both methods to accurately assess PBM efficacy.

Among the most frequently employed objective assessments are two-point discrimination and light touch tests. Most of the studies in this review [23,32,39-45] reported statistically significant improvements in VAS scores following PBM, as well as in several objective measures-except for thermal discrimination tests, in which no significant improvements were observed. These findings are consistent with those reported by Salari et al. [58] in their RCT evaluating PBM in patients with neurotmesis due to mandibular fractures. Similarly, results from the meta-analysis by Firoozi et al. [30] confirmed the lack of statistically significant improvements in thermal discrimination among patients undergoing sagittal split osteotomies [29,59].

Nevertheless, based on current evidence, it remains unclear which test modality is most responsive to PBM; further studies comparing different assessment tools are needed to determine which nerve fibres are most affected by the therapy.

Start of the therapy

Regarding the timing of PBM initiation, two studies [32,45] reported no differences in recovery between patients with injuries < 6 months and those treated after longer intervals. Conversely, Midamba and Haanaes [42] and Ozen et al. [40], in case series, reported statistically significant improvements in mechanoreceptive tests and VAS scores in patients with nerve injuries of more than one year, following PBM. These findings align with those of Mirzaei et al. [50], who documented improvements in both subjective and objective measures in patients with IAN injuries secondary to sagittal osteotomies, treated up to two years post-injury.

In contrast, Firoozi et al. [30] cautioned about the limited efficacy of PBM within the first 48 hours postoperatively. However, other studies suggest that early PBM can achieve 90 to 100% improvement in sensory function. These findings, however, are limited by the possibility of spontaneous recovery during the acute phase following nerve injury [32,43,56].

At the same time, evidence has demonstrated the relevance of prompt diagnosis and intervention. Current recommendations suggests that diagnosis should ideally be reached within 36 hours [60].

Patients’ satisfaction

With respect to patient-reported satisfaction, Pol et al. [32] noted that participants did not request additional therapy after completing the PBM protocol. These findings are consistent with those reported by Ebrahimi et al. [9], who assessed satisfaction across different stages of therapy using wavelengths of 810 nm and 940 nm, observing greater improvement in the 810 nm PBM group compared to both the 940 nm and control groups. Likewise, Fernandes-Neto et al. [31] reported complete patient satisfaction following PBM treatment.

Wavelength and dosage

A key factor in PBM efficacy is the appropriate selection of wavelength and dosage to ensure sufficient laser penetration into deep tissues. All studies included in this review employed GaAlAs lasers with wavelengths ranging between 808 and 830 nm, consistent with current scientific evidence supporting greater efficacy in the infrared range compared to the red spectrum [24,29,61,62]. Nonetheless, Pol et al. [32] used superpulsed wavelengths of 904 to 910 nm combined with continuous 650 nm light and reported favourable outcomes in sensory recovery. These findings are consistent with those of Mohajerani et al. [29], who observed positive outcomes following combined application of 810 nm and 632 nm wavelengths in patients undergoing sagittal osteotomies.

Despite evidence supporting the superior efficacy of infrared wavelengths (800 to 908 nm) in PBM, there is still no consensus regarding the optimal dosage. However, unfavourable outcomes appear to be more commonly associated with underdosing rather than overdosing. In their systematic review, Zein et al. [63] concluded that insufficient dosage may compromise laser penetration into deep tissues, where most mitochondria and nerve cells are located. In our review, only one RCT [45] failed to find significant differences between PBM and placebo, which may be attributed to the much lower dosage used (6 J intraoral and 3 J extraoral) compared to other studies that used energy levels ranging from 2.8 to 123 J per point.

Number of sessions and duration of therapy

Regarding the number and duration of sessions, no causal relationship can be established due to heterogeneity across studies, which reported between 7 and 20 sessions. Nevertheless, Mirzaei et al. [50] documented significant neurosensory improvements following PBM regardless of the number and duration of treatment sessions.

Follow-up

The long-term effects of PBM remain unclear due to a lack of follow-up in several studies and variability in follow-up duration among those that did, ranging from 30 days [23] to 24 months [44].

PBM and other therapies

Several studies [64-66] have proposed that B-complex vitamins-specifically B1, B6, and B12-play a crucial role in nerve regeneration. These so-called neurotrophic vitamins are essential for nervous system function and offer several physiological benefits. Vitamin B1 acts as an antioxidant, protecting nerves from oxidative damage [67]. Vitamin B6 is involved in neurotransmitter synthesis, inhibits neurotoxic glutamate release, and contributes to sensory function restoration [68]. Vitamin B12 supports neuronal regeneration, enhances cell survival, promotes remyelination, and maintains the integrity of myelin sheaths [69]. Collectively, these effects contribute to the restoration of nerve function, including sensory conduction velocity [70,71].

PBM has demonstrated benefits in nerve regeneration and peripheral neuromuscular repair by modulating cytokine and growth factor expression, helping regulate inflammation and improving the morphology of nerve tissues. While many studies have evaluated the individual effects of B vitamins and PBM, there is a significant lack of research examining the combined effect of both therapeutic strategies. In a 2024 rat study, Martins et al. [72] confirmed the efficacy of B-complex vitamins and PBM in pain relief and reduction of inflammation following nerve injury; however, the combination of both treatments did not demonstrate superior outcomes compared to either therapy used independently.

In our review, only the study by Qi et al. [23] compared PBM and oral mecobalamin (0.5 mg three times daily), finding greater efficacy in PBM administered via the post-extraction socket. Nevertheless, further studies are needed to compare the effectiveness of both therapies, as well as to explore potential synergistic effects when applied in combination for the treatment of IAN injury in humans.

Limitations

The main limitations of this review include the limited number of RCTs, small sample sizes, short or absent follow-up periods, and high variability in PBM parameters (wavelength, energy, fluence, irradiated points, duration, timing of the therapy), which currently prevent the establishment of a standardized therapeutic protocol for this type of injury.

Despite the demonstrated safety, non-invasive nature, and promising results of photobiomodulation in the sensory recovery of the inferior alveolar nerve following third molar extraction or dental implant placement, the current lack of high-quality randomized controlled trials with larger sample sizes and the significant methodological heterogeneity-particularly regarding aetiology, time from injury to treatment, and number of photobiomodulation sessions-precludes the establishment of a standardized treatment protocol.

It is therefore recommended that future research implement homogeneous protocols, particularly for variables with the greatest dispersion, such as treatment duration and timing, and further explore the combination of photobiomodulation with other therapeutic strategies to assess potential synergistic effects in nerve regeneration.