| Objective To evaluate the difference of adhesion force of silicone-based soft denture lined samples with its surface containing different sizes of microstructure of bio-inspired tree frog’s foot pads in the simulated oral environment and screen out the optimal parameters of bio-inspired tree frog’s foot pads.And,to provide a potential experimental technique for fabricating the "biomimetic adhesion complete denture" to improve the retention of the complete denture.Methods Firstly,the model of "biomimetic adhesion complete denture" was constructed.We designed four different sizes of bio-inspired tree frog’s foot pad micriostructure(hexagonal pillar side length × height × hexagonal pillar spacing: group A: 100 μm × 75μm × 33 μm;group B: 100 μm × 75 μm × 60 μm;group C: 40 μm × μm × 75 μm;group D: 40 μm × 75 μm × 50 μm),and then printed resin samples with a certain size(8 mm ×8 mm × 2 mm)containing inverse structure microarray of aforementioned bio-inspired tree frog’s foot pad microstructure by a 3D micro-printer(corresponding to the clinical edentulous digital scannig model with "inverse structure microarray of the bio-inspired tree frog’s foot pad microstructure" on the surface).Secondly,according to procedure of traditional clinical soft lined complete denture fabricating,we routinely duplicated the impression of the resin samples containing "inverse structure microarray of the bio-inspired tree frog’s foot pad microstructure" using addition silicone rubber impression material.And then,we poured the superhard stone model material onto the sueface of impression samples to obtain the superhard stone model containing the "inverse structure microarray of the bio-inspired tree frog’s foot pad microstructure." Finally,the silicone-based soft denture liner material was injected onto the surface of superhard stone model,obtaining the silicone soft lined samples with bio-inspired tree frog’s foot pad microarray structure on its surface(corresponding to silicone-based soft denture lined tissue surface of complete denture with bio-inspired tree frog’s foot pad microarray structure).Groups A,B,C and D were experimental groups,while smooth plane sample E was control group.The sample surface morphology of 3D printed and flipped by three materials was observed by scanning electron microscope(SEM)to evaluate the size error between the fabricating samples and the pre-designed samples containing "bio-inspired tree frog’s foot pad microarray structure," and to verify the feasibility of the potential technique.The adhesion force test was carried out in the simulated oral environment by electronic universal material testing machine.The microstructural size of bio-inspired tree frog’s foot pad with the best adhesion capacity was screened out.Results SEM results showed that the surface morphology of 3D printed samples of four groups A,B,C,D with the surface containing "inverse structure microarray of bio-inspired tree frog’s foot pad microstructure" was complete without obvious damage or bubbles,and the size difference comparing with pre-designed size was less than 2.4%.The microstructural morphology of the four groups samples of silicone rubber impression material flipped was basically consistent with the pre-designed morphology,without obvious bubbles.And the size difference comparing with pre-designed size was less than 4%,and the structural damage rate was less than 20%.The size differences of superhard stone and silicone-based soft denture lined samples after mold flipping were4.6% and 6.4% in group A,and 6% and 0.21% in group B,respectively.There was a great difference of microstructure morphology between group C,D and pre-design after superhard stone flipping.The pre-designed hexagonal micristructure morphology couldn’t be completely duplicated.Statistical analysis of the adhesion force showed that the adhesion force of experimental groups A and B were 0.23 ± 0.03 N and 0.14 ± 0.02 N respectively,which were significantly different from that of control group E 0.10 ±0.02 N(P < 0.05).There was statistical significance in adhesion force between group A and B(P < 0.05).Group A had the best adhesion force.Group C and D didn’t be carried out adhesion force test because the microstructure morphology didn’t meet the requirements.Conclusion The microarray structure of bio-inspired tree frog’s foot pad with appropriate size on the surface of silicone-based soft denture liner material can improve its adhesion capacity to other objects in vitro.It is technically feasible to fabricate the "biomimetic adhesion complete denture" with "bio-inspired tree frog’s foot pad microarray structure" morphology on tissue surface by 3D printing technology combined with the traditional technology of complete denture fabricating.This study may provide a new way to improve the retention of complete denture,but its clinical application needs further studies. |
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