Experimental Research Of Bacteria Adhesion On The Pure Titanium And Titanium Alloy With Different Surface Topographies

Objective:As technology continues to develop and mature,the dental implant has become the main means of clinical prosthetic techniques. But for now, the long-term success of implant denture still needs further improvement.Tested and clinically proven[1]: implant inflammation is one of the most important factors affecting long-term success rate, and formation of plaque biofilm on the implant plays an important role in its development. Experiment showed that [2], Streptococci and Actinomyces viscosus in oral environment,the early colonizers who provides a good environment and basic conditions for the formation of plaque biofilm, makes the putative pathogen, e. g. porphyromonas gingivalis(Pg) and Prevotella intermedia(Pi), adhering to implant and reproducing, result in imbalance of the flora and lead to implantation failure.There are still certain differences of organizational structure in neck of Implant compared with natural teeth, these weaknesses leading to the more invasion to the surface from microorganisms and toxic products[3].Therefore, designing a suitable implant surface topography of the neck to prevent bacteria adhesion is critical to ensure clinical success. This experiment in the hope that by comparing adhesion of early colonizers to the surface of pure titanium and titanium alloy, determine the surface who is against the formation of plaque, to find implant surface design of the neck for the long-term success.Methods:Chose Pure titanium and titanium alloy as test specimens and Streptococcus mutans(S.mutans UA159) as experimental strains. Round specimens were treated by different ways to get mechanical machining surface group(M),acid-etching surface group(AE) the electrolyticetching surface group(ECE), electro-etching and acid-etching surface group(ECA). After preparation, using scanning electron microscope(SEM) and laser scanning confocal microscopy(LSCM) to observe the characteristics of different implant surface morphology and measure the surface roughness.Using optical microscopy and Gram stain to identify the stable strain.Using scanning electron microscope(SEM) and MTT to observe and identify the test specimens which have been trained with S.mutans UA159 in a suitable environment.Results:1.Under the scanning electron microscope(SEM):In pure titanium group : the surface is relatively even and smooth on M specimen with the parallel stripes ravines;On the AE specimen,the surface is rough,there were full of 20-50 nm sharp processes; ECE specimen appeared as a rough surface with uniform 15-35 mm micro holes;On the rough surface of the ECA specimen there were full of 15-35 mm micro holes in which the 5-15 nm tentacle- like processes exist.In titanium alloy group: the surface is smooth on M specimen with the shallower parallel stripes ravines;On the AE specimen,the surface is rough,there were full of 20-50 nm sharp processes with round head; ECE specimen appeared as a rough surface with uniform 5-10 mm smaller bottom but bigger mouth holes, in the micro holes there were full of minor protuberances; On the rough surface of the ECA specimen there were full of 5-10 mm micro holes in which the 20-50 nm tentacle- like sharp-head processes exist.2.Under the laser scanning confocal microscopy(LSCM):In pure titanium group: there were parallel stripes ravines on the surface of M specimen;the vertical height of the AE specimen is inconsistent; ECE specimen had the ball-like spatial structure whose depth was 7.15um; ECA specimen had the ball-like spatial structure whose depth was 6.36um;In titanium alloy group: there were parallel stripes ravines on the surface of M specimen;the vertical height of the AE specimen is inconsistent; ECE specimen had the ball-like spatial structure whose depth was 6.96um;the ball-like spatial structure with different size of the ECA specimen were set fold,the main hole depth was 6.44 um.3.Roughness Measurement showed that:In pure titanium group: M group:Ra=0.393 um,AE group:Ra=0.451 um,ECE group Ra=1.542 um,ECA group:Ra=1.548 um.In titanium alloy group:M group:Ra=0.372 um,AE group:Ra=0.427 um,ECE group:Ra=1.536 um,ECA group:Ra=1.522 um.4.Bacterial identification showed that:On BHI solid culture medium, S.mutans UA159 appeared as smelless white bacterial colonies with irregular edge shapes; in BHI fluid nutrient medium, the light yellow liquid was clear. Under the optical microscopy, test bacteria were blue-purple spherical germ arranged as different length chain.5.Detection of bacterial adhesion showed that :Under the scanning electron microscope,the shape of bacteria in each experimental group was not significantly different. The amount of bacterial adhesion showed that: In pure titanium group: ECA>ECE>AE>M,there was significant difference between the ECE and AE, ECE and M,ECA and AE, ECA and M; there was no significant difference between ECA and ECA,AE and M.In titanium alloy group: ECA > ECE > AE > M,there was significant difference between the ECE and AE, ECE and M,ECA and AE, ECA and M; there was no significant difference between ECA and ECA,AE and M.There was significant difference between the groups in pure titanium and titanium alloy group with the same processing method.5.MTT showed that:In pure titanium group ECA>ECE>AE>M,there was significant difference between the ECE and AE, ECE and M,ECA and AE, ECA and M; there was no significant difference between ECA and ECA,AE and M.In titanium alloy group:ECA>ECE>AE>M,there was significant difference between the ECE and AE, ECE and M,ECA and AE, ECA and M;there was no significant difference between ECA and ECA,AE and M.There was significant difference between the groups in pure titanium and titanium alloy group with the same processing method.Conclusions:1.Through electrolytic etching technology, the micro surface and the micro-nano surface of pure titanium with 15-35 um micro-structured aperture and 7.15 um depth or through electro-etching and acid-etching technology,the micro surface and the micro-nano surface of pure titanium with 15-35 um micro-structured aperture and 6.36 um depth are conducive tobacterial adhesion, compared with the control group and the nano surface in acid-etching surface group.The nanostructure on the micro-nano surface have no significant influence on bacteria adhesion.2.Through electrolytic etching technology, the micro surface and the micro-nano surface of titanium alloy with 5-10 um micro-structured aperture and 6.96 um depth or through electro-etching and acid-etching technology,the micro surface and the micro-nano surface of titanium alloy with 5-10 um micro-structured aperture and 6.44 um depth are conducive to bacterial adhesion, compared with the control group and the nano surface in acid-etching surface group.The nanostructure on the micro-nano surface have no significant influence on bacteria adhesion.3.There was significant difference of bacteria adhesion between the machined surface in mechanical machining technology and the nano surface in acid-etching technology.