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Adhesion and Cements
Objective- GDC
DENTAL BIOMATERIALS SCIENCEInstruction in the properties, correct manipulation and the science underpinning the
use of dental materials is needed to equip the student with the knowledge to
select and handle those materials safely and effectively. Dental students need to
understand how such materials, and the biological responses to them, are
evaluated. This equips them to cope with future developments in this area. The
GDC considers it is essential that staff teaching this part of the programme work in
close collaboration with clinical colleagues.
have knowledge of the science that underpins the use of
dental biomaterials
have knowledge of the limitations of dental materials
be familiar with those aspects of biomaterial safety that relate
to dentistry
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Before Adhesive Dentistry-
How do you stick on a crown or inlay? Answer-
Classic Acid-Base Dental Cements
EGZinc Phosphate cement (introduced in1879)
Zinc Oxide /Eugenol (introduced in1894)
These are still in use- there used to be manymore
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How do they work?- To cement things in place
they are referred to as Luting Cements
Just like the mortar that holds bricks together
in a wall (Lutum= potters clay (latin))
Cement takes up the space between theprosthesis and tooth, and on setting provides
mechanical retentiveness (effectiveness
conditional on the geometry of the tooth
preparation
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Caution!
Luting is a term that relates to role not to
chemistry
Acid/Base Cements like Zinc Phosphate / Zincoxide / eugenol also used to be used as linings
and temporary dressings
For dressings etc. they are mixed to a
rather thicker consistency
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Zinc Phosphate- Classic luting Cement
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Recap
Classic Luting Cements are part of the
dental armamentarium that has been around
for ages
They tend to set by acid / base reactions
They tend to be multi-role materials that
when mixed thick can be used for linings
They are not strictly adhesive to tooth tissue
or to restorations (but may cling tenaciously to
clothing and instruments)
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Developments in Luting Cements
Since the arrival of composites and glass
ionomers this picture has become more
complex
Some Luting cements around that are
actually adhesives in the strict sense
Two sorts-
± Ionomer cements
± Resin Cements
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Developments in Luting Cements
Remember
± Micromechanical Adhesion comes from the
wetting and permeation of the microscopic
roughnesses of a material adherend(The
surface to which an adhesive adheres) by the
adhesive
±Chemical (specific) adhesion is a result of both theintimate wetting and permeation described above
AND attractive interaction between adherend
and adhesive
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Ionomer cements
Sticky because of the polyacid present butotherwise handles as a traditional Acid /
Base cement
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Ionomer cements
Poly-F (Zinc Polycarboxylate) cement
lacks the Glass bit of Glass ionomersIt is an acid base cement with some real stickiness
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Resin Cements
In essence these are runny composites (DONT
confuse with flowable composites)
Resin cements are used in conjunction with dentine
bonding agents and are capable of micro-mechanicalattachment to tooth structures and to surfaces of
restorations. This bonding is micro-mechanical in
nature and depends on surface microroughness.
Some resin cements are formulated to possess anadditional chemical agent claimed to enable them to
bond to restorations and may display some chemical
adhesion
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Resin Cements
Key Role-
± Cementation of Ceramics
±Porcelain is brittle
± If it is not BONDED in place by an adhesive it will
fracture
± An all porcelain restoration cannot be
successfully cemented with traditional luting
cements
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Resin Cements
Resin cements often claim clever means of getting chemical
adhesion but a resin cement has many characteristics in
common with Resins in general- it will flow into microscopic
features and adhere by wetting and permeation. Any real
chemical adhesiveness is in some ways still controversial
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Resin Cements
Panavia 21
Anerobic curing resin
cement
Opaque
Claims chemical adhesion
through phosphate esters in
resin
Often used to cement
metals to tooth-
± Resin retained bridges
± Metal/ceramic Crowns
Nexus 2
Dual Curing Resin Cement
Comes in a variety of shadesand opacities
Comes with try in pastes
so that aesthetics can be
fine tuned prior to
cementation
Often used to cement
translucent optically
linked restorations to tooth
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Rely X Luting Cement
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The Rely X Unicem on Clinic
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The Rely X Unicem on Clinic
What do you make of these claims?
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Dentine Bonding Agents Vs Resin
Cements Dentine bonding agents are resin materials
used to make a dental composite material
adhere to bond to both dentine and enamel
Resin Cements are resin materials used to
cement a restoration (usually made by indirect
means) to tooth tissue and/or restorations
already present
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Dentine Bonding Agents
Further Details Are available in the DVD
lectures to be found on VITAL- 2nd Year