Comparison of the Results of Biostimulation Treatment of Inferior Alveolar Nerve Injury Using Nd:YAG and Diode Lasers With Different Wavelengths.

Intraoral surgical procedures such as sagittal split osteotomy, dental implant placement, and surgical extraction of third molars are widely performed interventions in oral and maxillofacial surgery. Although these operations are generally safe and predictable, they may cause direct or indirect injury to the inferior alveolar nerve, one of the main sensory nerves of the mandible responsible for the innervation of the lower teeth, alveolar bone, gingiva, lower lip, and chin. Damage to this nerve can occur due to mechanical trauma, compression, thermal injury, or stretching during surgery, as well as following facial or mandibular trauma. As a consequence, patients may experience various neurosensory disturbances such as anesthesia, hypoesthesia, paresthesia, or dysesthesia. These conditions often result in discomfort, reduced functional capacity, and psychological distress, affecting both esthetic and functional expectations after surgical recovery. Restoring normal nerve function in such cases remains a major clinical challenge in oral surgery and neuromodulation research.

The inferior alveolar nerve follows a delicate anatomical path through the mandibular canal, where it is easily affected by surgical manipulations. Even minor trauma may lead to transient or permanent sensory dysfunction. The pathophysiology of such nerve injuries involves axonal degeneration, demyelination, and subsequent alterations in nerve conduction. Depending on the severity, nerve regeneration may occur spontaneously or may require therapeutic intervention. The degree of recovery depends on the extent of axonal disruption, the inflammatory response in the surrounding tissue, and the capacity of Schwann cells to facilitate remyelination. Traditional treatment approaches for inferior alveolar nerve injury include observation, pharmacological support, surgical decompression, or microsurgical repair. However, outcomes of these methods are often unpredictable, and recovery is slow. Therefore, noninvasive therapeutic modalities that can enhance neuronal healing and accelerate sensory recovery have become an area of increasing interest in modern dentistry and maxillofacial surgery.

Among these, the use of laser biostimulation-also known as low-level laser therapy or photobiomodulation-has gained significant attention as a noninvasive, safe, and clinically applicable method to promote nerve regeneration. Laser biostimulation involves the application of light energy at specific wavelengths to biological tissues, leading to a cascade of photochemical and photophysical effects at the cellular level. When absorbed by mitochondrial chromophores, particularly cytochrome c oxidase, the photons increase cellular metabolism, enhance ATP synthesis, stimulate DNA and RNA synthesis, and promote cellular proliferation and differentiation. In neural tissues, this process can lead to activation of Schwann cells, enhancement of neurotrophic factor secretion, reduction of oxidative stress, and modulation of inflammatory mediators, thereby creating a favorable microenvironment for axonal regrowth. Consequently, photobiomodulation represents an advanced therapeutic approach to accelerate neural healing following both iatrogenic and traumatic nerve injuries.

Two of the most commonly used laser types for biostimulation in clinical practice are diode and Nd:YAG lasers. Both operate in the near-infrared region of the electromagnetic spectrum but differ in wavelength, absorption characteristics, and depth of tissue penetration. The diode laser emits light typically between 800 and 1000 nanometers, with the 980-nanometer wavelength being one of the most widely used in dentistry. Its energy is well absorbed by melanin and hemoglobin, making it particularly effective in soft-tissue applications, wound healing, pain modulation, and superficial tissue regeneration. The Nd:YAG laser, operating at 1064 nanometers, has a longer wavelength that allows deeper tissue penetration. It is less absorbed by superficial pigments and more effective in reaching submucosal, muscular, and neural tissues. The differences in penetration depth and absorption profiles mean that while diode lasers are efficient for surface-level biostimulation, Nd:YAG lasers are more suited for stimulating deeper anatomical structures such as nerves and bone.