Dental Materials F9

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DENTAL MATERIALS F9



SPHEROIDAL/SPERICAL ALLOY

AMALGAM

o

Medium



Most successful restorative material



Grayish-black colored restoration

o

Smallest



Cannot be used in the facial surface of anterior teeth for aesthetic reasons

o

Best used

o

Advantages:



CLASS I, II, V (posterior teeth; lingual/palatal of anterior teeth; buccal pits)



Uses minimal liquid (Hg)



Core build-up material



More compact filling



CLASS III (distal of cuspid not seen clinically)



Less void in between



56% causes of failure due to faulty…



Makes stronger set



40% causes of failure due to improper handling of the material



Smoother surface finish



Resist tarnish and corrosion

o

o

o

May be controlled by both the manufacturer and dentist MANUFACTURER



MERCURY •

Purity (should be pure with a mirror-like appearance)



Particle size



Certified pure by USP (US PHARMATECOPEA)



Component alloy



Toxic in pure state



Selection of alloy and mercury

DENTIST

o

Inhalation of Hg vapor

o

Entry through pores in skin



Selection of alloy and mercury



When mixed with alloy, toxicity disappears



Proportioning of alloy and mercury



When an amalgam restoration is subjected to 80°C, the free form of Hg will rise to the surface



Trituration process •



Condensation process

Handpieces should have water to serve as coolant when manipulating amalgam



Burnishing



Carving



Finishing/polishing of amalgam

SELECTION OF ALLOY AND MERCURY •

ALLOY •

Combination of different metals



Dispensed in:



SILVER (Ag) o

65 – 75%

o

For strength of amalgam restoration

o

Too much will lead to expansion

TIN (Sn)

o

POWDER/FILING

o

25 – 27%

o

PELLET/TABLET

o

Too much will lead to shrinkage





DISPERSED/FINE CUT ALLOY

Powder placed in PHARMACEUTICAL PILL MILL



COPPER (Cu) o

6%

o

For strength of amalgam restoration

LATHE-CUT ALLOY o

Big particle sized •

ZINC (Zn)

o

1 – 2%

o

Too much will deoxidize amalgam restoration



Grainy is under triturated

will make the restoration not undergo discoloration



A little shiny

o

o

o

zinc + moisture (premature contact) leads to secondary/delayed expansion

o

PROPORTIONING OF ALLOY AND MERCURY



always more mercury than alloy



6:5



o

Manually proportioned

o

Fine cut

o

Can be 8:6

1:1 o



Remove surface coating of alloy so that it will be easily mixed with mercury



Reduces size of alloy



Provide proper union between alloy and mercury



Methods of Trituration: o

Uses MORTAR & PESTLE



Hold pestle in a PALM & THUMB GRASP manner to apply pressure



Mortar has slightly raised center to guide the trituration against the walls in one direction



Should be dine in hard, flat surface



45 – 60sec mixing time



Must look: •

Smooth

o

Should not cling at the sides of mortar



Should easily curl down at the sides of the mortar



it will cling when there is too much Hg



over trituration makes the mixture cling to the sides of mortar



rub on skin to make mixture homogenous (or make it into ropelike without breaking it at any certain length)



when it breaks, it means it is dry (there is too much alloy)



too much Hg makes it heavy; cannot make it rope-like



too much mercury makes it flat



too much alloy makes it round



correct consistency makes it spherical

HAND TECHNIQUE 



transfer to rubber dam sheath to do kneading and malling technique (continuation process of trituration…)

TRITURATION PROCESS

Mixing of alloy and mercury

Due to little/excess Hg at the start of mix

 Machine-proportioned in a capsule with fine alloy



Particles must be properly mixed

MECHANICAL 

Pre-mixed



Follow steps in instruction guide



Has plastic piston inside to serve as pestle



Advantages:





Shorter mixing time



Shorter setting time due to heat release

Disadvantages:



Eliminates…

-Rosette Go 031409 

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