Comparative Studies On Telescope Crown Retention Based On Different Materials

Objective: The study adopted pure titanium and all ceramic as the materials of inter crown oftelescope crown, and adopted pure titanium, Co-Cr alloy, gold deposition as the materials ofouter crown of telescope crown. Through in vitro simulation experiment comparing retention oftelescope crown which were made of different materials and methods of production afterlong-term use, discussing the relationship between the performance of materials of inter crownand retention, comparing retention of telescope crown which were made of common clinicalmaterials and ways, and providing reference for clinical choice on materials oftelescope crown.Methods: Making standard butment die with its neck diameter was5millimetres, height was6millimetres, and cohesion angle was4°. There was a1millimetre shoulder on neck edge.Dividing them into four groups randomly. Adopting pure titanium and all ceramic as thematerials of inter crown, and adopting pure titanium, Co-Cr alloy, gold deposition as thematerials of outer crown. Using grinder fixed position to ensure major axis of inter crown andouter crown coincident. Dropping the artificial saliva continually by perfusion tube to keep moistbetween inter crown and outer crown to simulate human oral environment. Simulatting outercrown wearing process with50N position pressure to make them combine. Ensuring the rate ofmovement of loading head was5mm per second and the rate of insertion/separationcyclicprocess was10times per minute during the insertion/separation cyclicprocess. Measuringthe max value of retention on tensile dislocation, the results adopted average value of six testspecimens per group. Record the value of retention when the first time, per200times in1-1000times, and per1000times in1000-8000times in sequence. Ending the test when a secondconsecutive value of some test specimen less than3N.Results:⑴There were similar value of retention between pure titanium inter crown group and allceramic inter crown group on initial stage, their difference had no statistical significance. But thevalue of all ceramic inter crown group retention was greater than pure titanium inter crown groupafter many times wear-pick cyclicprocess, and their difference had statistical significance (P＜0.05).⑵The value of pure titanium outer crown group retention was greater than Co-Cr alloyouter crown group, their difference had statistical significance (P＜0.05). The value of golddeposition outer crown group was greater than Co-Cr alloy outer crown group, their differencehad statistical significance (P＜0.05). The difference of retention value between pure titanium outer crown group and gold deposition outer crown group had no statistical significance when0-5000times cyclicprocess(P＞0.05), had statistical significance when6000-8000timescyclicprocess(P＜0.05).Conclusions:Based on same material of outer crown, all ceramic inter crown could reduce thedeclined rate of retention value of telescope crown as times of insertion/separation cycleincreased. Based on adopting all ceramic as the material of inter crown, the declined trend of theretention value of telescope crown which adopted pure titanium or gold deposition was slowerthan that adopted non-precious metals, and pure titanium and gold deposition could providelong-lasting retention.