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


2) Artificial hip jointsBasic materials : Stainless steel , Titanium and its alloy ,& UHMWPE


3) Substitute heart valve 4) Indian chitra heart valve


5) Vascular graftBasic materials : Polyurethane ,Teflon & Dacron


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)


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


Three types

Preventive materials.

Restorative materials.

Auxiliary materials.

Dental Materials - Anusavice

Preventive materials

Compomer

Hybrid ionomer

Glass ionomer cement

zinc silicophosphate cement


Restorative materials:

Cement

Bases

Amalgams

Resin-based composites

Compomers

Hybrid ionomers,

Cast metals,

Metal-ceramics

Ceramics

Denture polymers.


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.


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


Ceramic :

Bioactive ceramic

Bioglass , Glass ceramic

Bioresorble ceramic

Calcium phosphate

Bioinhert ceramic

Alumina , Zirconia and carbon


Polymers

Polytetrafluroethylene ( PTFE)

Polyethyleneterephthalate (PET)

Polymethylmethacrylate ( PMMA)


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

Diagnostic casts◦ preliminary◦ opposing

Indirect reconstruction◦ fixed◦ removable

Bite registration

Impression materials

1) Non-elastic

a) Plaster

b) Compound

c) Waxes

d) Zinc oxide eugenol

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

Inexpensive

Easy to use

Hydrophilic◦ displace moisture, blood, fluids

Stock trays

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

Better elastic properties

Clean, pleasant

Stock tray◦ putty-wash

Good working and setting time

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

Alginate 88%

Polyvinyl Siloxane 85%

Polyether 27%

Other 6%

01 biomaterials and impressions- dr. ritesh

Health & Medicine

impression materials

model materials

auxiliary materials

vascular graft basic

dental waxes

dental restoration

tendons dental implants

pharmaceutical sciencessome