Mechanics Research On Ti2448Alloy Pre Split Post In Vitro

Compared with teeth with vital pulp, teeth are more fragile after root canal treatmentbecause of losing of water and cracking of collagenous fiber in addition with defect ofteeth structure. In clinical work for prosthodontic doctors always suggested a post to beused for such kind of teeth to support the remaining teeth structure and recover thefunction of chewing to the biggest extent.Metal post has a proper physical properties and is easy for casting and machineryprocessing which is the longest used post systerm in clinical work. However while the lasttwo kinds of posts have a higher modulus of elasticity; as a result the treated teeth wouldalways suffer from vertical fracture. Fiber post has the most similar elasticity modulus todentin; as a result, teeth after fiber post treatment would have a better flexural capacity.Ceramic post has its advantage by the way of aesthetics, histocompatibility andbiosecurity. However if the ceramic post was fractured it would be difficult to be get outand the teeth need to have a second time for root canal therapy. What was more, the ceramic post was too expensive to popularize.Ti2448post was designed in a split form with a noble low elastic modulus bytitanium of β type. This type of post made up for the shortcomings of traditional metalpost for higher elastic modulus and fiber post for lower strength. What was more, the presplit Ti2448post whose modulus was most similar to the natural dentin could also relievethe inside stress of root canal to prevent root fracture.This study could be divided into three parts:1、Comparing study of the Anti-shearing Force of the Ti2448Preformation AlloySplit Root Post Adhesive by Four Binding MaterialsThis experiment aimed to investigate the differences of the anti-shearing force of theTi2448preformation alloy split root post adhesive by four binding materials and providethe experimental basis for choosing proper binding materials in clinical work for the novelTi2448preformation alloy split root post. We collected fresh extracted mandibular secondpremolars with only one root canal. Prepare the root canals and filled them withgutta-percha in vitro, then post tracts were prepared. All the samples were divided intofour groups randomly and in each group Panavia F Cement, RelyX Unicem, FujiPlusⅠ glass inomer, zinc phosphate cement respectively was used. After these treatmentswe embedded the model which connected with the tension bar of the universal mechanicexperimental machine to further carry out the anti-shearing force experiment. The loadingforce was paralleled to the long axis of the post with a1mm／min velocity. Then werecorded the maximal loading when the post separate from the experimental model. Theresults indicated that the anti-shearing force of the four groups were686.75±33.58N,573.30±22.15N,436.50±17.81N and309.35±13.63N respectively for the groups ofPanavia F Cement，RelyX Unicem,Fuji PlusⅠ glass inomer and zinc phosphate cement.Differences between each group have statistical significance. In conclusions, Panavia FCement were recommended for being taken into use in the clinical work for Ti2448preformation alloy split root post because of its greatest anti-shearing force. 2、Comparison of the flexure capacity strength of dental structure after treatment oftwo titanium pre split post with different elastic modulusThis experiment compare the anti fracture strength and fracture patterns of dentalstructure from teeth which was treated with TC4and Ti2448alloy pre split post. We firstmake root canal treatment of maxillary canines in vitro and amputated the crown. TC4andTi2448post was used and embedded them into self-curing plastic with silicon to simulateperiodontal ligament. Metal bases were used to fix the in vitro teeth and the long axes ofthe teeth were130oto the experimental machine. The pattern of the fracture and theindications given by the machine were recorded. SPSS was used to analyze the statistics.The result indicated that the anti fracture resistance existed differences between Ti2448pre split post (67.08±8.96kg) and TC4pre split post (55.66±4.27kg) with statisticalsignificance. Conclusion: the Ti2448pre split post with low modulus of elasticity couldsatisfy the need of clinical work and it could also effectively avoid the stress concentrationfor the residual root with a good perspective.3、Comparison of the anti fatigue resistance of dental tissues repaired by the two presplit post with different modulus of elasticityThis experiment compared the failure pattern and anti fatigue resistance differencesbetween the two groups of pre split post. The in vitro teeth models were the same withprevious experiment and were45ofixed in the metal bases. The anti fracture resistancewere indicated by the reading of the fatigue machine and pattern of the fractured teeth.The resulted indicated that the root fracture places were different between the two groups.Conclusion: compared with TC4pre split post with higher modulus of elasticity, theTi2448post had a better anti fatigue characteristic and a higher chance to be repaired afterfracture.