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Preventive dental
materials
Preventive dentalPreventive dental
materialsmaterials
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Why are they used? To prevent injury or disease.
Three classes of materials areinvolved
Fluoride gels Pit and fissure sealants
Mouth protectors
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Fluoride Gels: acidulated sodium fluoride gels
contain 2% sodium fluoride (or more) +hydrogen fluoride + phosphoric acid.Fluoride ion concentration 1.22-1.32%.Stannous fluoride maybe used too.
Rinses: sodium fluoride or stannousfluoride
Varnishes
* Some products have pH of 6-8 to preventacid etching of restorations
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Rinse
Varnish
Gel
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Properties
Help to reduce smooth surface cries
Effectiveness depends on method ofapplication and frequency andduration.
A gel should be viscous enough forease of handling but fluid enough to
flow all around teeth
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Manipulation
Fluoride gel in trays: teeth clean and dry,patient should bite for 4 minutes and notrinse for 30 minutes
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Pit and fissure sealants To prevent pit and
fissure caries Pits and fissures are
enamel faults,inaccessible tocleaning using toothbrushes
Another method toseal fissures is usingair abrasion thenflowable composite.
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Composition and reaction Similar composition to resin composite but
more fluid. MOSTLY ACTIVATED BY VISIBLE LIGHT 2 component systems are activated by
peroxide initiator and amine activator Components:
Bis-GMA UDMA
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Examples
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Properties Physical and mechanical properties
depend on the product. Bonding is mechanical by acid etching
done to: Clean the surface Improve wettability
Create a rough surface
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Properties Sealant penetration maybe difficult due
to: Air entrapment Food debris accumulation
Penetration of sealant into fissure
depends on: Penetration coefficient of sealant: Surface tension Viscosity of sealant
Contact angle of sealant with enamel
Configuration of fissure (length, diameter)
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For sealants to be effective they
have to be retained. Reviews are important to replace
deficient sealants If caries exists under sealants,
studies showed that the number ofbacteria is low.
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When a sealant is not
used Uncooperative patients
If molars are caries free for a longtime
If there are no pits an d fissures
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Application
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Mouth protectors
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General points Made from polymers
Formed by heat to fit over teeth
Used to protect from injury or asvehicle to apply fluoride or bleachingmaterial
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Types and composition
Stock Mouth formed
Custom made: preferred, due to: Better comfort
Lack of bad odor or taste Minimal impaired speech Durability
But more expensive than other types
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Composition Custom made: in sheets 1.6-3 mm
thick Thermoplastic polymer (poly-vinyl
acetate-polyethylene polymer) or calledethylene vinyl acetate (EVA)
Other products: rubber latex
Polyurethane Vinyl plastisol.
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TypesCustom made
Mouth formed
Stock
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Properties
ADA specifications consider physical,mechanical properties
EVA properties before and afterinsertion into oral cavity are
different. Inside the mouth, theybecome more flexible, better impactstrength, but less tensile strength
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Compared to other
products Polyurethanes: higher strength,
hardness, higher water sorption,need higher processing temperatures
Plastisol and rubber latex haveslightly lower strength and hardness
compared to EVA but are difficult toprocess
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Complaints Gagging
Discomfort
Irritation
Bad taste
* Not common if mouth guard is made
properly.
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Continue,
Thicker mouth guard is stronger butmore uncomfortable
A final thickness of 4 mm isdesirable over incisal edge and cusps.Usually 2 thin sheets are used to
compensate for shrinkage
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Failures
Bite through, chewing through,tearing
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Parafunctional habits affect the
longevity of mouth protectors Deformation may occur due to
improper storage (in heat, tightspace
Should be stored on stone model orin a rigid container
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Fabrication Taking an impression
Pouring a model
Forming the thermoplastic material
on the model (by hand, pressurelamination, vacuum)
Finishing
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How is it made?
Palatal area is
not needed
V d
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Vacuum and pressure
lamination techniques
Both are moreaccurate than by hand
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Technique continue, Model is centered
Sheet is heated Lowered onto the model
Vacuum to fit the sheet on model Cooling
If primary teeth are erupting aspacer is placed
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Continue, Trimming: 3 mm above labial fold, clearance for
frenum Edges should be smooth by flame torching themthen smoothed with fingers
For occlusal adjustment: occlusal surface isheated than placed inside patients mouth inocclusion.
If vertical dimension is to be increased extra
layers of polymer are placed when soft then asecond layer under vacuum.
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Hand forming technique Sheet is softened in boiling water for
20 seconds Adapted by fingers on model and held
by wet towel Trimmed and finished
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Maintaining mouth guard Clean teeth
Clean mouth guard occasionally
Do not use abrasive
Do not use alcohol
Store in container provided
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References Dental materials, properties and
manipulation chapter 3.