cemented and cementeless implants and bone cement characteristics, Sintesi del corso di Biomateriali II

Scarica cemented and cementeless implants and bone cement characteristics e più Sintesi del corso in PDF di Biomateriali II solo su Docsity! CHAPTER 2 -- MECHANICAL PROPERTIES : IMPLANT VS BONE BONE CEMENT : PMMA IMPLANT BONE Filler material inserted in the bone without chemical reactions . Mechanical strength Implant > 5. SBONE Spoon 130 MP9 Elastic modulus | timpani 4 Epson] EBONE = 18 Gpa 22 It'%¥Epo&EY{ a part of liquids .Thoughtless K implant 2) KBONE KBONE =3 ÷ 8M¥ Powder components : Tm - copolymer beads based on PMMA - benzoyl peroxide : initiate - radiopacifier If Emma = 230 GP9 the material is too much - antibiotics : no more than 2% because they lower the mechanical stiffen , when it is coupled with bone the mechanical properties of the cement . Liquid components :¥:÷:i::: ÷÷::÷÷:÷÷÷÷÷÷:÷÷::÷÷÷÷÷÷÷÷÷÷:÷÷÷:::÷:÷:/Wolff 's law : the bone in a healthy person willremodel in response to the load it is 121%) a small number of polymer moleculesplaced on dee . because the molecular distanceif the loading decreases the bone will between free MMA molecules decreases .become less dense and weaken because It leads to a reduced bone mass andthere is no stimulus for remodelling . stability.The load that is carried by the bone Toxicity : doting polymerization , some MMA moleculesare released into the sooooonoting tissues .in the presence of an implant will becarried by two structures and the MMA is toxic because it causes oleopping ofstress on the bone is reduced . pressure . } setting time - CEMENTED STEMS plastic solid Bone cement (PMMA) is used to affix the prosthesis to the Porosity bone because it deies fast . Radio pacifiers § antibiotics can act as flaws/ :÷÷÷÷÷÷÷:÷÷÷÷÷÷:÷÷:/ :÷÷÷÷÷÷÷±÷:÷i÷ ÷:*:*porosity won't compromise theimplant and bone , it transfers properly fracture strength of bone cement .compression forces from the implant tothe bone avoiding the stress shielding Macroporosity has to be eliminated by :phenomenon . - hand mixing : 7% of porosity- centrifugation : liquid 9 powder components one hand mixedEpmmaI 3 GP9 EBONE I 18 Gpa Implant - 210 GP9 and then centrifugationd < 2% of poaosity EPMMA 4 EBONE G Eimplant - vacuum mixing : bone cement components one mixed under 1 :÷÷÷÷:÷:÷:÷÷÷:÷÷:÷÷÷:÷÷÷÷÷÷÷÷:÷:÷ ÷÷÷÷÷÷÷÷:÷:÷÷÷÷÷÷: ÷:::÷::÷÷::÷:÷:/3 : 2 BONE CEMENTMade in Co - Cr alloys oe Ti alloys because they can → greater safety : lower toxicity due to the release of less MMApassivote → less heat release : less MMA generates less heator less volume shrinkage : the amount of monomer is reduced so also shrinkage is reduced improving implant fixation . F-