Download - 01 biomaterials and impressions- dr. ritesh
Biomaterial refers to any non-vital material
intended to interact with biological system
within or on the human body.
Dental materials inserted into the oral cavity
therefore belongs into the group of biomaterials.
Biocompatibility of Dental materials – Schmalz & Bindslev .
Biomechanics is the study of the structure and function of biological systems such as humans, animals, plants, organs, and cells by means of the methods of mechanics.
The relationship between the biologic behaviour of oral structures and the physical influence of a dental restoration.
GPT, 2008
Joint replacements
Bone plates
Bone cement
Artificial ligaments and tendons
Dental implants for tooth fixation
Blood vessel prostheses
Heart valves
Skin repair devices
Cochlear replacements
Contact lenses
International Journal of Pharmacy and Pharmaceutical Sciences
1) Intra-Ocular lensBasic Materials : PMMA ( acrylic ) , Silicone
International Journal of Pharmacy and Pharmaceutical Sciences
2) Artificial hip jointsBasic materials : Stainless steel , Titanium and its alloy ,& UHMWPE
International Journal of Pharmacy and Pharmaceutical Sciences
3) Substitute heart valve 4) Indian chitra heart valve
International Journal of Pharmacy and Pharmaceutical Sciences
5) Vascular graftBasic materials : Polyurethane ,Teflon & Dacron
International Journal of Pharmacy and Pharmaceutical Sciences
Some commonly used biomaterials
1. Silicone rubber
2. Dacron
3. Cellulose
4. Poly( methyl methacrylate )
5. Polyurethanes
6. Hydrogels
7. Stainless steel
8. titanium
9. Alumina
10. Hydroxyapatite
11. Collagen (reprocessed)
International Journal of Pharmacy and Pharmaceutical Sciences
Applications• Catheters, tubing
• Vascular grafts
• Dialysis membrane
• Intraocular lenses, bone cement
• catheters, Pacemaker leads
• Ophthalmological devices, Drug delivery
• Orthopaedic devices, stents
• Orthopaedic & Dental devices
• Ophthalmologic applications, wound dressings
International Journal of Pharmacy and Pharmaceutical Sciences
Three types
Preventive materials.
Restorative materials.
Auxiliary materials.
Dental Materials - Anusavice
Preventive materials
Compomer
Hybrid ionomer
Glass ionomer cement
zinc silicophosphate cement
Dental Materials - Anusavice
Restorative materials:
Cement
Bases
Amalgams
Resin-based composites
Compomers
Hybrid ionomers,
Cast metals,
Metal-ceramics
Ceramics
Denture polymers.
Dental Materials - Anusavice
Auxiliary dental materials are substances that are used in the process of fabricating dental prostheses.
e.g. acid etching solutions ,impression materials, casting investments, gypsum cast and model materials, dental waxes, acrylic resins etc.
Dental Materials - Anusavice
Tribology is the “science and technology of interacting surfaces in relative motion” and encompasses the study of friction, wear and lubrication. By extension biotribology is usually defined as the tribologicalphenomena occurring in either the human body or in animals.
Biotribology J. Paulo DavimJ.
Biocompatibility (biomedical therapy): Ability of a material to perform withan appropriate host response in a specific application.
Biocompatibility: Ability to be in contact with a living system without producingan adverse effect.
GPT 2005
Implant : To graft or insert a material such as an alloplastic substance, an encapsulated drug, or tissue into the body of a recipient.
Material used for fabrication of implant are characterized into
>Chemical point : metals and ceramic.
> Biological point : biodynamic materials : biotolorent , bioinhert, and bioactive.
Biomaterial for dental implant : An overview
GPT 2005
Metals and alloys
Titanium
Titanium alloy
>Ti-6Al-V
>Ti-30Pd
Cobalt-chromium-Molybdenum alloy
Iron-Chromium-Nickel based alloy
Alloys of gold , platinum , & palladium
Biomaterial for dental implant : An overview
Ceramic :
Bioactive ceramic
Bioglass , Glass ceramic
Bioresorble ceramic
Calcium phosphate
Bioinhert ceramic
Alumina , Zirconia and carbon
Biomaterial for dental implant : An overview
Polymers
Polytetrafluroethylene ( PTFE)
Polyethyleneterephthalate (PET)
Polymethylmethacrylate ( PMMA)
Biomaterial for dental implant : An overview
1. The material must be biocompatible Nontoxic, nonirritating
Nonallergenic, noncarcinogenic
Chemically minimally degradable or its degradation process are biocompatible
2. Should possess appropriate optimal physical property
Adequate mechanical properties such as hardness, elasticity, and strength.
Adequate wear resistance.
Prosthodontic treatment for edentulous patient
Adequate thermal coefficient of expansion and conductivity properties.
Adequate esthetic properties.
Ease of cleansing.
Relative ease of fabrication and manipulation.
Readily available and economical to use.
Allow for easy and inexpensive maintenance such as repair and addition.
Prosthodontic treatment for edentulous patient
1. They should have low enough viscosity to adapt to the oral tissue, yet viscous enough to be contained in the impression tray.
2. The materials should have adequate wettabilityof the oral tissue to allow for the accurate adaptation and capturing of the oral structure and tissues.
3. Material must have pleasant taste and odor.
4. In mouth the material should set into a rubbery or rigid solid in reasonable amount of time.
5. Upon removal from the mouth, the set impression should show adequate elastic recovery with no permanent deformation.
6. The material must have adequate strength to avoid tear or breakage upon removal from the mouth.
7. The material must be dimensionally stable after setting and until pouring of the cast.
8. The impression can remain dimensionally stable to be repoured after removal from the cast.
9. The material must be compatible with the cast material.
10. The material must be biocompatible , nontoxic, and without irritant constituents.
11. The material must be of a colour and opacity that allow for proper evaluation of the impression by the dentist.
12. The material could be readily disinfected without significant loss of accuracy or loss of mechanical properties.
13. The materials must have adequate shelf life for storage.
14. The materials associated processing time and equipments should be cost-effective.
Non-elastic Elastic◦ Aqueous hydrocolloids Agar
Alginate
◦ Non-aqueous elastomers Polysulfide
Silicones Condensation
Addition
Polyether
2) Elastic materials
a) Aqueous hydrocolloids
> Reversible ( Agar)
> Irreversible( Alginate )
b) Non-aqueous elastomer
>Polysulfide
>silicone
1) Condensation silicone
2) Addition silicone
> Polyether
Impression plaster
It was used as a “mucostatic’’ impression material.
It does not compress and displace tissue during seating of the tray.
Applicable to patient with displaceable soft tissue that should de recorded in a passive state.
Components : calcium sulphate hemihydratewhich reacts with water to form calcium sulphate dihydrate which is homogenous in consistency.
Properties:
Dimensionally stable
It has low viscosity before setting
It is nonelastic, fracture may come across when their is an undercut
1. Mainly used for final impression of edentulous ridge with minor or no undercuts.
2. As a wash impression with other materials such as impression compound.
3. As an occlusal registration materials.
4. Used as a temporary liner material for denture.
5. Used as a surgical dressing.
Types of impression compound:
1. Type I ( lower fusing material)
e.g. Impression cakes , green stick.
2. Type II ( Higher fusing material) : It is used as a tray adaptation material. It is used for making a primary impression and used as a tray to support a thin layer of a second impression materials.
1. Thermoplastic resin.
2. Waxes.
3. Fillers ( for viscosity ).
4. Shellac.
5. Stearic acid.
6. Gutta percha. ( plasticity and workability )
Reversible Hydrocolloid (Agar)
Indications
They are considered one of the most accurate materials for recording fine details because of its low viscosity.
Example◦ Slate Hydrocolloid (Van R)
Agar◦ complex polysaccharide
seaweed
◦ gelling agent
Borax◦ strength
Potassium sulfate◦ improves gypsum surface
Water (85%)
Dimensionally accurate Hydrophilic◦ displaces moisture, blood, fluids
Inexpensive◦ after initial equipment
No custom tray or adhesives Pleasant flavor No mixing required
Initial expense◦ special equipment
Material must be prepared in advanced Tears easily Dimensionally unstable◦ Must be poured immediately◦ Can only be used for a single cast
Difficult to disinfect
Setting process of hydrocolloids is called gelation.
It is a solidification process that involves phase changes from sol to gel states.
The gel transforms into sol condition when heated to 70˚ to 100˚ C is called liquefaction temperature.
When cooled to (between 37˚and50˚ C) the gel transfer to sol and is called gelationtemperature.
Irreversible hydrocolloid Alginate Indicationsstudy modelsremovable fixed partial dentures Framework
Preliminary impression of the edentulous patient
Examples◦ Jeltrate (Dentsply/Caulk)◦ Coe Alginate (GC America)
Component
Potassium alginate : Soluble alginate
Calcium sulphate dihydrate : Reactor
Zinc oxide : Filler particles
Potassium titanium fluoride : Accelerator
Diatomaceous earth : Filler particles
Sodium phosphate : Retarder
Tears easily Dimensionally unstable◦ immediate pour ◦ single cast
Lower detail reproduction High permanent deformation
First dental elastomers Indications◦ complete denture◦ removable fixed partial denture tissue
◦ crown and bridge
Examples◦ Permlastic (Kerr)◦ Omni-Flex (GC America)
Base◦ polysulfide polymers
◦ fillers
◦ plasticizers
Catalyst◦ lead dioxide (or copper)
◦ fillers
By-product◦ water
Lower cost◦ compared to silicones and polyethers
Long working time
High tear strength
High flexibility
Good detail reproduction
Poor dimensional stability◦ water by-product◦ pour within one hour◦ single pour
Custom trays Messy◦ paste-paste mix◦ bad odor◦ may stain clothing
Long setting time
Indications◦ complete dentures
◦ crown and bridge
Examples◦ Speedex (Coltene/Whaledent)
◦ Primasil (TISS Dental)
Base◦ poly(dimethylsiloxane)◦ tetraethylorthosilicate◦ filler
Catalyst◦ metal organic ester
By-product◦ ethyl alcohol
Poor dimensional stability◦ high shrinkage polymerization
evaporation of ethanol
◦ pour immediately within 30 minutes
Hydrophobic◦ poor wettability
AKA: Vinyl polysiloxane Indicationscrown and bridgedenturebite registration
ExamplesExtrude (Kerr)Express (3M/ESPE)Aquasil (Dentsply Caulk)Genie (Sultan Chemists)Virtual (Ivoclar Vivadent)
Improvement over condensation silicones◦ no by-product
First paste◦ vinyl poly(dimethylsiloxane)
prepolymer
Second paste◦ siloxane prepolymer
Catalyst◦ chloroplatinic acid
Highly accurate
High dimensional stability◦ pour up to one week
Stock or custom trays
Multiple casts
Easy to mix
Pleasant odor
Expensive Pumice teeth before
impression Short working time Lower tear strength Possible hydrogen gas releasebubbles on diepalladium added to absorb
Indications◦ crown and bridge◦ bite registration
Examples◦ Impregum F (3M/ESPE)◦ Permadyne (3M/ESPE)◦ Pentamix (3M/ESPE)◦ P2 (Heraeus Kulzer)◦ Polygel (Dentsply Caulk)
Highly accurate Good dimensional stability Stock or dual-arch trays Good surface detail Pour within one week◦ kept dry
Multiple casts Good wettability
Expensive
Short working time
Rigid◦ difficult to remove from undercuts
Bitter taste
Low tear strength
Absorbs water◦ changes dimension
Zinc oxide eugenol impression can be disinfected by immersion in a 2% alkaline glutaraldehyde solution then rinsed and poured .
Impression compound can be safely disinfected by immersion in sodium hypochlorite, iodophors, or phenolicglutaraldehydes.
Agar can be disinfected by immersion in sodium hypochlorite, iodophor, and glutaraldehyde , rinsed and then poured in stone.
To control infection and microbial contamination in alginate, disinfectant materials, such as chlorhexidine acetate or quaternary ammonium are added.
Elastomeric impressions
Disinfected adequately by immersion in an
iodophor, diluted hypochlorite solution,
chlorine dioxide, glutaraldehyde, or complex
phenol for the time required for
tuberculocidal activity.
Crown & Bridge◦ vinylpolysiloxane 81%◦ alginate 38%◦ polyether 28%
Inlays and Onlays◦ vinylpolysiloxane 71%◦ polyether 22%◦ alginate 20%
Complete dentures◦ Alginate 58%◦ Vinylpolysiloxane 55%◦ Polyether 27%
Partial dentures◦ Alginate 78%◦ Vinylpolysiloxane 43%◦ Polyether 15%
Working time◦ longest to shortest
agar > polysulfide > silicones > alginate= polyether
Setting time◦ shortest to longest
alginate < polyether < agar < silicones < polysulfide
Stiffness◦ most to least
polyether > addition silicone > condensation silicone > polysulfide = hydrocolloids
Tear strength◦ greatest to least
polysulfide > addition silicone > polyether > condensation silicone >> hydrocolloids
Cost◦ lowest to highest
alginate < agar = polysulfide <condensation silicone < addition silicone < polyether
Dimensional stability◦ best to worst
addition silicone > polyether > polysulfide > condensation silicone > hydrocolloid
Wettability◦ best to worst hydrocolloids > polyether > hydrophilic addition
silicone > polysulfide > hydrophobic addition silicone = condensation silicone
Castability◦ best to worst hydrocolloids > hydrophilic addition silicone >
polyether > polysulfide > hydrophobic addition silicone = condensation silicone