Effects Of Er:YAG Laser And Nd:YAG Laser With Different Energy On The Surface Morphology And Bone Regeneration Capability Of Titanium Implant

Background:In recent years,the oral implants have been used more and more widely in the treatments of dentition defect,defect and maxillofacial defect treatment.With the widespread development of the oral implant,the incidence of peri-implantitis gradually increased.Peri-implantitis is mainly characterized by gingival inflammation,periodontal pocket formation,bleeding on probing or empyema,and bone resorption.The statistics of the incidence of peri-implantitis vary according to the standard.But it is reported in the literature that the incidence of peri-implantitis is 12%?43%.Therefore,there is a need to find an effect:ive method to treat peri-implantitis.The traditional metal scraper and ultrasonic cleaning will damage the titanium surface,form a rough surface,cause plaque deposition,so traditional techniques such as manual curette and ultrasonic tip treatment of the inflammation around the implant is not ideal.Leonhardt reported a faliure rate of 42%.Some scholars have used resin-based cleaning devices,carbon fiber ultrasonic cleaning tips,pressure jet mill systems and other special methods to remove plaque.However,these methods have different disadvantages.The laser has the advantages that mechanical treatment does not have in sterilizing and removing toxins on the surface of the implant,and can increase the biocompatibility of the implant surface.The application of laser therapy,with its clear mechanism and the manifestation of clinical effects,has been extended to more and more scholars to treat peri-implantitis.More and more scholars have extended it to the treatment of peri-implantitis,but the efficacy needs to be verified.Purposes:Er:YAG laser and Nd:YAG laser has different advantages in sterilizing around implants,removing soft and hard tissues,and promoting tissue healing around implants.However,with higher power,the laser may change the surface morphology of the implant,affecting its cell adhesion and bone regeneration capacity.Whether there is a difference in the change of the surface morphology of the implant with different energy lasers and whether this change will affect the bone regeneration capability of the implant is the purpose of this experiment.Methods:1.In vitro experiments:Grouping:A total of 27 SLA surface treated titanium discswere randomly divided Er:YAG laser group,Nd?YAG laser group,and blank control group.Er:YAG laser group with 12 titanium discs components A,B,C,D four subgroups,using R14 hand tools,set the MSP irradiation mode,the frequency is 20Hz,the irradiation power is A group 40mJ,B group 70mJ,C group 100mJ,D group 150mJ;Nd:YAG laser with 12 titanium discs components A,B,C,D four subgroups,using MSP mode,the frequency is 15Hz,fiber is 300um,irradiation power is A group 1W,B group 1.5 W,C group 2W,D Group 3W.The blank control set a piece of titanium.Laser irradiation:The tip of the fiber is 1 mm away from the surface of the titanium disc,and the irradiation angle is 45° with the surface of the titanium disc.Cool with aseptic saline during irradiation.The surface of the titanium disc is moved at a speed of 2 mm/s.The surface morphology of the titanium discs was analyzed by scanning electron microscopy.The titanium discs were placed in a sterile 24 well plate and human osteosarcoma MG-63 cells were inoculated.Samples were harvested 8 hours and 24 hours after inoculation,and the cell adhesion on titanium disc surface was observed by scanning electron microscope.2.Animal experiments:A total of 32 Wego(?)3.4×11mm implants were randomly divided into Er:YAG laser group and Nd:YAG laser group,each of four subgroups A,B,C,and D.In the Er:YAG laser group,the R14 handpiece was used and set the MSP irradiation mode,the frequency was 20 Hz,and the irradiation energy was respectively 40 mJ for group A,70 mJ for group B,100 mJ for group C,150 mJ for group D;In the Nd:YAG laser group,MSP mode was used,and the frequency was 15Hz,the optical fiber is 300um,the irradiation energy is respectively 1W in group A,1.5W in group B,2W in group C,and 3W in group D.The surface of the implant was marked with a and b sides.The a surface was the laser irradiation surface,and the b surface was the blank control surface that set as group E.The tip of the fiber was 1 mm away from the surface of the implant,with an angle of 45°,Cool with aseptic saline during irradiation.Irradiate the implant at a speed of 2 mm/s.Four international standard male Beagle dogs were selected and surgical procedures were performed according to the Wego implant system.Four implants were prepared in the range of 2-9 cm from the proximal tibia to the knee of each Beagle dog.Four implants were implanted.the dogs were sacrificed at 2 weeks,4 weeks,8 weeks,and 12 weeks after surgery.32 bone specimens with implants were prepared for gross specimen observation and bone slices with implants.After the Ladewig staining,the histological observation was performed by an optical microscope.The hard tissue sections were analyzed by a semi-automatic digital image analyzer.The total length of the contact surface between the new bone and the implant and the total length of the implant embedded in the bone tissue was recorded.Calculate the Bone-implant contact(BIC),SPSS software was used for statistical analysis of the data with one-way variance(One-Way ANOVA).And experimental results were obtained.Results:1.In vitro experiments? Er:YAG laser group:In the power range set by the experimental group(40mJ-150mJ),no obvious melting,condensation and other changes occurred on the surface of the titanium disc.Nd:YAG laser group:Scanning electron microscopy observation shows that when the power is less than 1.5W,the surface of the titanium disc is not changed significantly,and there is no significant difference with the control group.When the power is higher than 1.5 W,the surface of the titanium disc shows melting,condensation and micro-cracks.The degree of change is proportional to the power output.? Er:YAG laser group:After 8 hours of cell inoculation,the cells protruded pseudopodia and adhered tightly to the surface of the titanium disc.Compared with the control group,the cells in the experimental groups with different power(40mJ-150mJ)adhered well to the surface of the titanium disc.There was no significant difference among the groups;after 24 hours of cell inoculation,the number of adherent cells on the surface of the titanium disc increased compared to that at 8 hours after inoculation,and there was no significant difference in cell morphology among the groups.Nd:YAG laser group:After 8 hours of cell seeding,cell adhesion was observed on the surface of the titanium disc.When the power was less than 1.5 W,the adherent cells on the surface of uthe titanium disc spread evenly around the surface,and there was no significant difference compared with the control group;When the power was higher than 1.5W,cells had less pseudopodia outstretched on the surface of the titanium disc,and the cell expansion range was smaller.24 hours After the cells were inoclated,the number of adherent cells on the surface of the titanium plate increased compared to that at the time of inoculation of 8 hours,but no significant change in the cell adhesion shape was observed.2.Animal Experiments2.1 Implant implantation:Implant implantation was performed smoothly.Beagle dogs had good wound healing after operation.No inflammatory reaction was found and they were all healthy.2.2 Observation by light microscope:?Er:YAG laser group:New bone formation around the implants was observed in the experimental group and the blank control group at 2 weeks postoperatively;no significant difference was observed between the groups;4 weeks postoperatively compared to 2 weeks postoperatively Peripheral bone formation was significantly increased in the experimental group and the control group.There was no significant difference between the experimental group and the control group.Bone remodeling around the implant was basically completed at 8 weeks and 12 weeks after surgery.There was no significant difference between the experimental group and the control group.?Nd:YAG laser group:a small amount of new bone was generated around the implant in the experimental group and the control group at 2 weeks postoperatively.No significant difference was found between the groups.There was an increase in new bone formation around the implant at 4 weeks after surgery.The group A,B,and E was slightly more than the C and D groups,covering the top of the implant;at 8 weeks after surgery,there were more new bone around the implants in groups A and B and E than in the groups C and D;at 12 weeks after surgery,group A,B,and E compared with group C and D,the amount of new bone around the implants was significantly different.2.3 Histomorphological analysis:?Er:YAG laser group:At four time points,there was no significant difference in the BIC between the groups(p>0.05);?Nd:YAG laser group:2 weeks after operation and 4 weeks after surgery,there was no significant difference in the BIC between the groups(p>0.05).After 8 weeks and 12 weeks after surgery,the BIC in groups A,B,and E were significantly higher than those in groups C and D(p<0.05).There was no significant difference in the BIC among groups A,B,E and C,D(p>0.05).Conclusion:1.Er:YAG laser with power lower than 150mJ and Nd:YAG laser with power lower than 1W have no obvious effect on the surface morphology of SLA-treated titanium disc.The power of Nd:YAG laser with power higher than 1.5W makes the surface of titanium disc to appear melting,condensation and microcracks.The scale of damage is proportional to the power output.And these changes influences the cell adhesion morphology on titanium disc surface.2.Er:YAG laser with a power lower than 150mJ and Nd:YAG laser with a power lower than 1.5 W does not affect the bone reconstruction and has no effect on the BIC.3.Nd:YAG laser with power higher than 2W are harmful to the formation of bone around the implant,reducing the BIC.