Table 1.

A summary of the in vitro studies relevant to the evaluation of DC electrical stimulation effects on osseointegration

Reference	Cell type	Cathode material	Electrical configuration	Stimulation	Stimulation duration	Results
Gilbert et al. [53]	Osteoblast (rat calvaria)	cpTi (Grade 4)	Potentiostatic (3 electrode)	− 1000 mV (vs. Ag/AgCl)	2 h	Constant cathodic polarization of titanium substrates depleted oxygen from the adjacent microenvironment and reduced osteoblast spreading on the titanium
Kalbacova et al. [56]	Osteoblast (MG63)	Ti–6Al–4V (ASTM 136)	Galvanostatic (2 electrode)	− 2.5 µA/cm2 − 5 µA/cm2	24 h	Reductions in osteoblast viability and morphology that was associated with an increased intracellular production of reactive oxygen species
Ehrensberger et al. [41]	Pre-osteoblast (MC3T3-E1)	cpTi (Grade 4)	Potentiostatic (3 electrode)	− 600 mV − 1000 mV (vs. Ag/AgCl)	24 h	85% reduction in viability and spreading of pre-osteoblasts cultured on titanium samples when polarized at a constant cathodic potential
Sivan et al. [57]	Pre-osteoblast (MC3T3-E1)	Ti–6Al–4V (ASTM F136)	Potentiostatic (3 electrode)	− 400 mV (vs. Ag/AgCl) [~ 20nA/cm2]	10 h	Cell death can occur at in as little as 10 h with an associated average cathodic current density of − 20 ηA/cm2
Haeri et al. [55]	Pre-osteoblast (MC3T3-E1)	cpTi (Grade 4)	Potentiostatic (3 electrode)	− 400 mV (vs. Ag/AgCl)	24 h	Viability of cells cultured onto polarized titanium can be enhanced by pre-treatment anodization of the titanium sample
Ciolko et al. [38]	Pre-osteoblast (MC3T3-E1)	cpTi (Grade 2)	Shifting Cathodic Potential (3 electrode)	− 750 mV (vs. Ag/AgCl)	24 h (1 s on, 5 s off)	Cell viability was not affected by periodic cathodic shifting of the potential of titanium substrates
Gittens et al. [54]	Osteoblast (MG63)	cpTi (Grade 2)	Potentiostatic (2 electrode)	− 100 mV	2 h	Cathodically polarized titanium substrates enhance osteogenic differentiation of human pre-cursor cells in a voltage-dependent manner