The Effect of Electric Currents on New Cementum Formation during Periodontal Wound Healing

Since Yasudea observated that a small amout of electricity stimulates osteogenesis in 1953, this original concept has been verified and considerably expanded by many investigators. We have determined the direct electric currents of 10 microamperes stimulates the bone remodeling and osseous callus formation in the alveolar bone and mandible. This study designed to determine the effect of direct electrical stimulation on new cementum formation during the periodontal wound healing.In three adult mongrel dogs, two pairs of surgical bony defects were made bilateraly in the mandible. A pair of defects was constituted of the cathodic defect between the second premolar and third premolar, and the anodic defect between the third and fourth premolar. The electrodes were stainless wires 0.7 milimeter in diameter, insulated by Teflon tube without one milimeter from top ends, netted in the bottom wall of bony defects on each side of the mandible. A pair of electordes on the left side connected to the implantable power pack unit for the delivery of a constant, continuous direct currents of 10 microamperes, that was constituted of a dual FET, a resister and silver oxide battery.Evalution of the dynamics of appositional cementum was facilitated by the subcutaneous administration of oxytetracycline, that began on Day 15 of the experiental period with the use of a schedule of 3 days on, 7 days off, and 3 days on. The dosage was 200mg/day.Not-stained bony sections (100 microns) were horizontally cutted, and were viewed under the fluorescence microscope. Morphometric measurements were performed with the Nikon's eyepiece type micrometer and the Zeiss's integrating disk type II. We measured 5 cross-sections of the each side of the mandible. The following 5 parameters were measured on 4 quadrants of each root, distal root of the second premolar, mesial root of the third premolar, distal root of the third premolar and mesial root of the fourth premolar.1) Mean ratio of Tc labeled surface to root surface (%)2) Mean ratio of Tc double labeled surface to root surface (%)3) Mean thickness of labeled cementum (μm)4) Mean appositional rate of cementum (μm/day)5) Mean width of periodontal ligament (μm)The ratio of labled surface and double labeled surface were higher valure in cahtode than control site, and not different in anode, in all quadrants. The appositional rate and thickness of the cementum were higher value in cathode and anode than control in all quadrants. The width of periodontal ligament was not different between the electrical stimulated site and control, and was larger value in A quadrant in that new bone formation. The direct electric currents stimulated the cementum formation on root, and expanded the adaptive area, and accelated the adaptive speed in this process.