Lecture # 8

30/3/2011

Cement II

Hey guys ….hope u fine….

Hey el mo7adaraaah kaanaat yooom el 2rbe3aaaaa 8abeel 2mte7anat w ma 7ederha ella 11 taleb…

DR.sa7aar kanaat t3leee8 3a slide mojaraad t3lee8 3a 2saas enoooh el slides ma3aak fa feeh 2$yaaa2 mo mawjodeeeh be sheet cuz e DR ma 7kthooom bas mawjodeen fe slides w lajneeeh 2keed ra7 tnazeelhooom fe tl3 el 3li ma$koreeen salaafaan.

2ma bensbeeeh la record ma kaaan feeh record fa sajlt el mo7adaraah 3al mobile fa lel2saaf mo kol e$iii waade7 :/

sheet 3melthaa 3a $ekeel note bas mojarad letsheeel ..

Today we will take about cement II …

  • One of the disadvantage of zinc oxide-eugenol is the weakness >so we added alumina particle or resin (polymer resin forced zinc oxide eugenol cement(modified zinc oxide –eugenol)
  • EBA alumina modified cement :--
  • We added alumina particle to zinc oxide & the liquid don’t change just like zinc oxide eugenol
  • The aim of addition of alumina particle in the mixture to form a crystalline structure & to be stronge
  • Fe 2r8aaaam mawjodeen fe slides ma 7akthoom fe record ( and the DR said >just to have an idea :D
  • The modified zinc oxide-eugenol(stronger) use as liner & temporary filling material for long time (month or even more)
  • The zinc oxide-eugenol (without addition) use as temporary filling material for short time ..EX.for two week just for example
  • We manipulate modified zinc oxide-eugenol by: mix it circular, vigorous motion & we added the powder to the liquid by small incremental addition
  • Resin (polymer reinforced zinc oxide eugenol cement)
  • Zinc oxide the major constituent of the powder but we added to the powder resin & it’s already reactive (nafs fekret el filler fe el composite)
  • Liquid :eugenol & liner constituent & we can use luting agent as a base
  • Luting agent :is a viscous material placed between tooth structure & a prosthesis,that hardens through chemical reaction to firmly attach the prosthesis to tooth structure..[Wikipedia]
  • The difference between liner & base :- is the thickness :liner is much thinner than the base
  • The modified zinc oxide-eugenol after the addition----1-improvement the chemical property to be use as base more than filler 2-we can use it as temporary filling material 3-decrease the sitting time to 10 minute rather than 24 hours !!!! just to be accurate:-the sitting time 6-10 minute 4-compresive strength improved by the addition..5- improve the mechanical property:- toughness & resistance
  • Manipulation :-powder/liquid ratio 4:1 & vigorous spatulation
  • Zinc phosphate cement( new title :D)
  • The oldest cement
  • It’s the standard to the other cement cuz it’s the oldest (when we compare the new cement with zinc phosphate cement)
  • The application>we can use it as luting agent for crown & bridges
  • Crown: etalbeseeeh …..el bridge: ta3wwe9’ la e$II missing :D
  • High strength >.so we can use it as base
  • Temporary restoration ( temporary filling )
  • Mechanical property for zinc phosphate cement better than zinc oxide-eugenol cement
  • All the cement NOT used as permanent filling material
  • We can use it in the orthodontic application: to stick the tooth to the orthodontic>thin layer tab3n :D
  • ADA classify the zinc phosphate to type I & type II depending on the grain size
  • Fine grain for type I & medium grain for type II
  • Film thickness for type I>25 micrometer or less ……for type II 40 micrometer or more
  • In the cement<kol ma kant the luting agent thinner> - more desirable & better
  • Zinc phosphate cement available as powder/liquid or capsule ( powder& liquid are measured >2ryaa7 elaak ya doc :D)
  • The constituent:
  • In the powder : zinc phosphate as major ingredient as well as cilica & Mg
  • In the liquid: phosphoric acid 40% ,water, alumina not sure about that cuz e record hooon ma kaan wadee7 >t2kaad men el slides
  • The reaction:-acid-base reaction …….zinc oxide + phosphoric acidacid zinc phosphate
  • Acid zinc phosphate will react with un-reacted powder to form structure called *** mo wadee7 erjaa3 la slides> I know 3aj8aaah :P
  • The structure was formed has a good & desirable properety & it’s insoluble & hard as well as strong mechanical property
  • The previous reaction is acid-base reaction and it’s exothermic so it makes a trouble during the handling & mixing . ..shit !!
  • We have enough working time & short sitting >good not bad <
  • How to manipulate??--> optimal ratio 3 gram: 1ml
  • For the luting agent >work time 3-6 minute & sitting time 5-14 minute and it depends on the mixing procedure & mixing ratio
  • the constituent will make it thick for base agent or thin for lining agent
  • we manipulate the powder & liquid in a glass slab
  • we devide the powder to six portions( equal portions ) baas bel kotooob bekooon 5 portoins and DR. said Six bekooon 27saan fa 23tamed e six portion :D
  • we mix every portion alone
  • we use a LINEAR motion & SWEEP the mixture and spread it on a WIDE surface cuz the reaction is EXOTHERMIC [to spend the heat and lose it ] :D
  • mechanical property will be lower if we mix on small area why ya $atr??-->cuz we will effect on powder/liquid ratio> the liquid will evaporate and it will effect on the composition>the chemical property will change…..capito :P
  • the total mixing time 90 second so> take your time when u mix (90 second mo z3’ereeh betkafiii lel mix mo zy ma bethy2laaak)
  • rapid mixing will shorten the sitting & working time so >take a care cuz maybe will be intial sitting & you still work !!! (decreasing the working time )
  • to spend the heat :-1- use a large or wide surface when you still mix ( to lose the heat) 2- use a cold glass slab
  • cold glass slab use for all kind of cement
  • all of this will increase the working time & it allow to incorporate more amount of the powder on the liquid soimprove the mechanical property & become stronger as well as reduce the solubility
  • if the amount of the powder less than the liquid dissolved intraoraly it will reduce the strength and the solubility resistance
  • water contamination must be avoided cuz it accelerate the reaction
  • you should be careful when you store the liquid and the powder > if u tarkt el 3elbeeeh bedooon 3’ataaaa nsethaa mathaaalaaan kal 3adeh :Pthe liquid will evaporate  PH decreaseliquid not clear (turbid) you should not use it as a dentist ya 7abebi cuz ra7 t3’lbaak bel mixing ya dentist entaah
  • fe 9owaar fe slides ta3teaaak an idea bas lamaa testalem e slides m9awaraah 7ykooon 2soaad a 2wbee9’ fa ra7t 3aleak :P
  • the desired constancy of the cement ( 28rab t3beeer wjdtoooh ) zy e super glue :D ( bemooot ya3niii )it will be viscous and you have at least 1 inch on the spatula
  • if you attaned less than 1 inch cement is runny & weak (el powder ratio less & we need more powder & it will be soluble in the oral cavity
  • if the cement more viscous we can’t use it as a base agent but we can use it like lining agent
  • the zinc phosphate cement is acidic el PH 1.3-3.6 but it will be neutral after 24 hours
  • zinc phosphate does not have antibacterial effect
  • The effect of low PH ??!!-->the most acidic when we make mixing within the 24 hours (the trouble) …when the cement on direct contact with dentine  it will affect on the fluid in the dentine tubule & it cause a pressure on the pulp so it cause a sharp sensation of pain> fa ya 7abeeb emmaak 3adiii el wajaa3 ra7 yroo7 ma t5aaf b3d 24 hours >it will be neutral ..capito :D hope that ..
  • the zinc phosphate (exothermic) during the sitting  so it will shrink ( full sit ) fa 3a$aaan heaak mo 3’alt law zedet el kamyeeh $Oy 3a$AAN ra7 ykooon fe shrinking bas bel 3a8eeel !!
  • if the cement thin (more liquid) ,it will affect on the mechanical property and it will cause sensitivity in the oral cavity> so0o Bad <
  • Harding process take 24 hours sowhen we put the cement we will notice intial sitting & final sitting
  • Intial sitting 6-10 minute and it will be hard & it gain 80% of its property (80% roughly)
  • After 24 hours (final sitting)it will gain 100% of its property
  • Always there are some ability of solubility for the cement & within 24 hours there are significant release of some Zn & Mg  it indicates the cement is soluble ( relatively tab3aan) and always when we ( mo 27na el amercaan tabaaa3aan) discover new cement ,we (hommeeh) turn to overcome this disadvantage
  • Mechanical property :- 140 mega paskal !!!!! t2kaad plz men slides mo wade7 9otha la2nha kant troo7 w tejeee allaah ysame7aa 7awltnaaa
  • Intial strength within 6-14 minute
  • Final strength after 24 hours
  • Thermal property :again back la slides lel2saaf mo wade7 bas ma t5aaf maktooob fe slides …I’m sorry for that
  • It’s reduce the galvanic ( electrical) effect (due to dissolved metals <ZN,Mg>)
  • The solubility
  • We don’t matter about the solubility when we use it as base cuz it will cover by permanent filling material
  • If we use it as luting or lining agent between tooth structure & crown ,it will be exposed to the oral cavity & if it(cement) soluble there are microleakage below the crown so we will lose the restoration & the bacteria will do her job :D
  • The solubility range between 0.04%- 0.33% & the acceptable level until 0.2%
  • If it exceed 0.2%  we will lose the restoration & we will have caries
  • Anything in the oral cavity and the cement will exposed to the acid from the food & form the bacteria especially lactic acid and the acid will dissolve the cement..

Sorry 7abybii ma kaan fe record yooom el 2rbe3a 8abel el examz w tab3aan ma3thoreeeeeen fattreat 2sajeel 3al mobile fa fe naw8ee9 mo 3’lt terja3 la slides w net bas enet 3aje8haa bezyaadeeh lamaa 7awlt 2tlee3 e nawwaa8e9

Mn la ya$kor enaaas la ya$kor ellaaaah …..

Fa 2t8adaaam be jazeeel e $okr nyabataan 3aniii a w3n tolaab dof3tnaa la 239’aa2 lajnetnaa 3ala ma 8aamt behe men jhood w taantheeem w 3njad allah ya3tekooo 2lf 3afyeeh ya na$aamaa > go ahead..

Any correction more and more than welcome …

HOPE ALL OF YOU DONE WELL IN MID-TERM EXAMzzz

I want to dedicate this sheet to a large # of names and really I’m confused so0o0o> this sheet dedicated to everyone read it without any exception

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