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

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

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

Exclusion criteria

• Systemic diseases known to impair peripheral nerve regeneration, including diabetes mellitus (any type), peripheral neuropathy of any aetiology, multiple sclerosis, or other demyelinating disorders.
• Pregnant women are excluded
• Patients with cognitive impairment are excluded
• History of hypersensitivity or adverse reaction to laser therapy of any type.
• 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.
• Genioplasty performed