Nd:YAG Laser Photobiomodulation for Neurosensory Recovery Following Bimaxillary Orthognathic Surgery

Nd:YAG Laser Photobiomodulation for Neurosensory Recovery Following Bimaxillary Orthognathic Surgery: A Randomised Sham-Controlled Double-Blinded Clinical Trial

This study investigates whether low-energy laser light therapy applied to the skin (photobiomodulation, PBM) can speed up recovery of sensation in the lower lip, chin, and cheek area following jaw surgery (bimaxillary orthognathic surgery). Numbness and altered sensation in these areas are common and expected side effects of jaw surgery, affecting approximately one third of patients at 12 months without active treatment. There is currently no proven non-invasive treatment to accelerate nerve recovery after jaw surgery.

Eligible participants who develop numbness after jaw surgery will be randomly assigned to receive either active PBM laser treatment or an inactive sham laser treatment (6 sessions over 3 weeks). Neither the participant nor the assessor measuring recovery will know which treatment was received. All participants also receive standard postoperative care.

The study aims to determine whether active PBM significantly reduces the time to functional sensory recovery compared with sham treatment, and to characterise recovery patterns using a standardised multicomponent neurosensory assessment battery over 12 months.

Neurosensory disturbances affecting the inferior alveolar nerve (IAN) and infraorbital nerve (ION) are well-recognised expected sequelae of bimaxillary orthognathic surgery, arising from surgical manipulation during sagittal split ramus osteotomy (SSRO) and Le Fort I osteotomy respectively. Published incidence data from a major Asian orthognathic centre (Alolayan and Leung, University of Hong Kong, PLoS ONE 2014, n=238) reported subjective IAN neurosensory disturbance rates of 35.4% at 6 months and 36.6% at 12 months following mandibular SSRO, and ION disturbance rates of 16.2% at 6 months and 13% at 12 months following Le Fort I osteotomy. These figures represent persistent clinically significant deficits in a substantial proportion of patients at a major Chinese-majority Asian tertiary centre, making them the most directly applicable published proxy for the expected NUH study population.

Current management of post-orthognathic neurosensory deficits is expectant. In cases of non-recovery beyond six months, pharmacological options or microsurgical repair may be considered, but both carry limited efficacy data and significant procedural risk respectively. There is a clear unmet need for safe, non-invasive adjunctive interventions capable of accelerating neurosensory recovery.

Photobiomodulation (PBM) involves the application of low-energy laser irradiation to stimulate mitochondrial cytochrome c oxidase, increasing ATP production, modulating reactive oxygen species, and upregulating neurotrophic factors including nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). These effects promote axonal regeneration, Schwann cell proliferation, and remyelination. A recent randomised controlled trial (Kayim et al., Journal of Oral and Maxillofacial Surgery, 2026) comparing Nd:YAG and diode laser PBM versus no-treatment control in 30 post-orthognathic patients reported IAN functional sensory recovery (FSR) rates of 90% in laser-treated groups versus 40% in controls at 12 months (log-rank p=0.001; adjusted hazard ratio 8.04, 95% CI 2.03-31.90). However, that study lacked a sham control, leaving placebo-adjusted efficacy unestablished. The present study addresses this critical gap with a fully sham-controlled, double-blinded design.

Inclusion Criteria:

1. Age 21-80 years and above at time of orthognathic surgery.
2. Underwent bimaxillary orthognathic surgery (SSRO and Le Fort I osteotomy), without genioplasty
3. Willing and able to comply with the full 12-month follow-up schedule comprising 12 visits.

Exclusion Criteria:

1. Systemic diseases known to impair peripheral nerve regeneration, including diabetes mellitus (any type), peripheral neuropathy of any aetiology, multiple sclerosis, or other demyelinating disorders.
2. Pregnant women are excluded
3. Patients with cognitive impairment are excluded
4. History of hypersensitivity or adverse reaction to laser therapy of any type.
5. Surgical complication directly attributable to the orthognathic procedure that required reoperation or microsurgical nerve repair, as these represent a fundamentally different injury severity and recovery trajectory from the neurapraxic and axonotmetic injuries targeted by this study.
6. Genioplasty performed