Inhibitory Effect Of Heat-polymerized Acrylic Resin Immersed In Organosilicon Quaternary Ammounium Salts On Cadida Albicans

Objective:The aim of the present study was to investigate the inhi biting effect of the heat-polymerized acrylic resin treated with serial Si-QAS concentrations on Candida albicans and the long-term inhibitory ou tcome on Candida albicans by means of thermocycling test providing a reference for clinical work.Methods:1.Material:a.Specimen Preparation174 specimens with a size of 10mm*10mm*1.0mm heat-polymerized acrylic resin were fabricated using traditional heat-polymerization method according to the manufacturers’instructions.Six sides opposite plaster sides are roughend by manual abrasion with emery paper under running water from200 grit,400 grit to 600 grit along with the same direction 50 times.Afterwards,cleaning ultrasonically all specimens at room temperature for 20minutes and immersing specimens in the sterile distilled water for 7 days to remove any residual monomer.Meanwhile,we exchanged sterile distilled water every other 24 hours until the 7^th day when we rinsed specimens in ultrasonic device 3 times for 20 minutes,after which we soaked specimens the last day.Finally,making a replication of the aforementioned cleaning process and waiting for later use after air dry for 24 hours.b.Antimicrobial treatment144 specimens selected from the prepared ones were randomly catigorized into six different Si-QAS concentration groups（Group A to F）,each of which in turn is 1%,5%,10%,20%,40%,and the control group was F:sterile distilled water.In each group aforementioned,we reclassified four different time subgroups:30 min,60 min,120 min and 240 min.After immersion treatment,rinsing the treated specimens gently with 2 ml sterile distilled water for three times to remove unattached Candida albicans and replaced them the new 24 hole cell culture plate waiting for later use after air dry for 24 hours.c.Candida albicans species（ATCC 90028）RecoveryAfter thrawing candida albicans（ATCC 90028）,we mixed freeze-dried powder with strain solution evenly by way of streak inoculation on the Sabouraud’s plate and incubated at 37℃for 48h.Selection of single fungal colony from the Petri dish by means of sterile swabs spread evenly on the walls of the test tube after inocubating for 48 hours.Blowing and blending the suspension slightly to adjust it to 0.5 Mc Farland standards to match the turbidity of 1.5*10⁸/ml colony forming unit（CFU）utilizing sterile RPMI 1640liquid medium for later use.2.Methodsa.Inhibition of Cadida albicans test:Randomly locating the treated specimens vertically into 24-pore plate and adding perpendicularly different concentration solutions by a pipettor into each pore according to respective immersion time.Afterwards,take out each specimen and rinse 3 times in sterile tubes using 2ml sterile distilled water.Replace the air dried specimens respectively into a new 24-pore cell plate and add perpendicularly prepared fungal suspension into each pore by a pipettor to cultivate them at 37℃for48h.Then,rinsing specimens gently respectively in 2ml sterile distilled water and transferring them respectively to a new 24-pore plate incorporating new sterile RPMI 1640 culture medium,after which we put them on the flash mixer to vibrating candida albicans attached to specimens into the RPMI 1640culture medium,and then transferring the suspensions into the turbidimetric tubes respectively and recording the data twice for an average using turbidimeter,specifically,zero setting before turbidimetric analysis is a must.b.Thermolcycling test:We may draw a conclusion that the optimal treatment condition is:immersion in 20%Si-QAS for 60min,namely,utilizing it as the antimicrobial treatment condition in the thermocycling test after making a statistical analysis for the data obtained from Inhibition of Cadida albicans test.30 heat-polymerized acrylic resin specimens were selected randomly and divided into five groups（Group G-K）,the former four groups（G-J）were performed antibacterial treatment according to the procedures above mentioned and then made thermolcycling 0,2500,5000,10000 times,while the control group was only immersed in the sterile disditilled water.Afterwards,the treated specimens were put into a new sterile 24-pore plate containing 1ml 0.5M fungal suspension and incubated at 37℃for 48h.Additionally,rinsing the specimens gently with 2ml sterile distilled water and replacing them into a new 24-pore plate incorporated in 1ml sterile RPMI1640 culture medium.Ultimately,recording the data twice for an average using turbidimeter after vibrating 1 min on a falsh mixer.In particular,zero setting before turbidimetric analysis is a must.Results:1.Inhibition growth of Cadida albicans test:we can draw a conclusion through factorial design analysis of variance that different treated concentrations have a significant effect on inhibition of Candida albicans（F=79.779,P<0.01）,and diverse process time has also a significant effect on inhibiting efficacy on Candida albicans（F=5.227,P<0.002）.There is an interaction between concentration and treated time（F=5.386,P<0.01）.We arrive at a conclusion by making a S-N-K multiple comparison that:there is a significant difference between experimental groups and the control group（P<0.05）,while there exists no significant difference among the any other group except for group A,B,C and group D,E.It suggests that heat-polymerized acrylic resin specimens treated with Si-QAS manifest inhibitory effect on Candida albicans,whose inhibition effect will strengthen as higher concentration.We can draw a conclusion by making a S-N-K multiple comparison that any other group exists no significant defference but immersion for 30min,60min,120min and 240min.We may see that heat-polymerized acrylic resin specimens immersed in 20%QAS for 60min can reach an optimal antimicrobial outcome by further analysis.2.Thermolcycling test:One-way analysis of variance was performed for data from group G to group K.We can come to a conclusion through comparing different cycles that:there exists a significant difference just between group G and control group K（P<0.05）but not any other group,which suggests a distinct inhibitory effect of heat-polymerized acrylic resin specimens treated with Si-QAS on Candida albicans,and also there exists an influence between thermocycling and inhibitory effect.Additionally,we may draw a conclusion by means of pairwise comparison of various cycles that:only the control group K has a significant difference in contrast to other groups,while the other groups does not,demonstrating wakening the inhibitory effect of thermocycling on Candida albicans.Heat-polymerized acrylic resin loses potential antimicrobial properties undergoing 2500 thermal cycles,indicating that heat-polymerized acrylic resin specimens combine with Si-QAS loosely.Conclusions:We can draw a conclusion in the limited experimental condition th at:The heat-polymerized acrylic resin treated with Si-QAS solutions can reduce adhesion of candida albicans and the optimal treatment condition is:immersion in 20%Si-QAS for 60min.In addition,the inhibitive eff ect of heat-polymerized PMMA treated with 20%Si-QAS solution for 60min is lost after undergoing 2500 cycles,indicating a temporary antimi crobial potential.