Effectiveness and Mechanisms of Low-Intensity Pulsed Ultrasound on Osseointegration of Dental Implants and Biological Functions of Bone Marrow Mesenchymal Stem Cells

Table 1

Summary of LIPUS studies on implant osseointegration and peri-implant bone regeneration.

Studies	Animal models	Titanium implants	LIPUS parameters	Time of stimulation	Major conclusions
Ustun et al. [27]	New Zealand rabbits; Tibiae	Length: 6.0 mm; Diameter: 4.1 mm; Screw-shaped	Intensity: 30 mW/cm^2 (/SATA); Pulse frequency: 1.5 MHz	20 min/day for 1, 2, 3, 4, 5, and 6 weeks	LIPUS may have positive effects on osseointegration and stability of dental implants
Kang et al. [28]	Mongrel dogs; Mandibular bone	Length: 8.5 mm; Diameter: 3.3 mm	Intensity: 240 mW/cm^2 (/SATA); Pulse frequency: 3.0 MHz	15 min/day for 1 week	LIPUS may have a positive effect on osseointegration and stability of dental implants, especially in early healing periods
Zhou et al. [29]	SD rats; Tibiae	Length: 4.0 mm; Diameter: 2.0 mm; Pitch: 0.6 mm; Screw-shaped	Intensity: 30 mW/cm^2 (/SATA); Pulse frequency: 1.5 MHz	20 min/day for 4, 8, and 12 weeks	LIPUS therapy may accelerate the bone healing and osseointegration at the interlace between titanium implant and bone and promote remodeling of bone trabecula in the early stage
Nakanishi et al. [30]	Japanese white rabbits; Femur	Length: 10 mm; Diameter: 3.3 mm	Intensity: 40 mW/cm^2 or 100 mW/cm^2 (/SATA); Pulse frequency: 1 MHz or 3 MHz	20 min/day for 2 weeks	Clinical application of LIPUS for dental implants may promote osseointegration
Hsu et al. [31]	New Zealand rabbits; Tibiae	Length: 8 mm; Diameter: 3.6 mm; Screw-shaped	Intensity: 50, 150, and 300 mW/cm^2 (/SATA); Pulse frequency: 1 MHz	10 min/day for 30 days	LIPUS at 0.05–0.3 W/cm^2 intensity may accelerate cell proliferation and promote the maturation of collagen fibers and support osteointegration
Liu et al. [32]	New Zealand rabbits; Femur and tibiae	Length: 18 mm; Diameter: 2.5 mm; Screw-shaped	Intensity: 40 mW/cm^2 (/SATA); Pulse frequency: 1.5 MHz	10 min twice a day (total 20 min) for 3 weeks	LIPUS has the potential to accelerate the osseointegration of dental implants
Zhou et al. [33]	Ovariectomized SD rats; Tibiae	Length: 4.0 mm; Diameter: 2.0 mm; Pitch: 0.6 mm; Screw-shaped	Intensity: 40 mW/cm^2 (/SATA); Pulse frequency: 1.5 MHz	20 min/day for 2, 4, 6, 8, 10, and 12 weeks	LIPUS may enhance new bone formation, especially in an early stage, and improve osseointegration in osteoporotic bone as an auxiliary method
Ruppert et al. [34]	SD rats; Femur	Length: 20 mm; Diameter: 1.5 mm	Intensity: 30 mW/cm^2 (/SATA); Pulse frequency: 1.5 MHz	20 min/day for 4 and 8 weeks, 5 days per week	LIPUS is superior to vibration for accelerating osseointegration and increasing bone–implant failure loads at 4 weeks
Jiang et al. [24]	αCGRP^+/+ and αCGRP^-/- mice; Maxillary first molar extraction sockets	Length: 1 mm; Diameter: 0.6 mm; Screw-shaped	Intensity: 30 mW/cm^2 (/SATA); Pulse frequency: 1 MHz	20 min/day for 2 and 4 weeks	LIPUS can enhance osseointegration of dental implant by inducing local neuronal production of αCGRP, providing a new idea to promote peri-implant osseointegration and bone regeneration

CGRP: calcitonin gene-related peptide; LIPUS: low-intensity pulsed ultrasound; SATA: spatial average temporal average; SD: Sprague–Dawley.