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576 Biocompatible materials - LV 308.106 Classification of dental cements Type I: Luting agents* that include temporary cements Class 1: powder-liquid -> harden Class 2: paste-paste -> remain soft Type II: Luting agents for permanent applications Type III: Temporary liner or base applications Type IV: Permanent liner or base applications *) A material that acts as an adhesive to hold together the casting to the tooth structure.

Classification of dental cements - vowi.fsinf.at · Elastomers Alginate irreversible Hydrocolloids reversible flexible Impression materials. Biocompatible materials - LV 308.106 583

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576Biocompatible materials - LV 308.106

Classification of dental cements

� Type I: Luting agents* that include temporary

cements

– Class 1: powder-liquid -> harden

– Class 2: paste-paste -> remain soft

� Type II: Luting agents for permanent applications

� Type III: Temporary liner or base applications

� Type IV: Permanent liner or base applications

*) A material that acts as an adhesive to hold together the casting to the tooth structure.

577Biocompatible materials - LV 308.106

Applications of dental cements

• Underfilling or liner (materials for protection

of dental pulp against mechanical and chemical )

· Temporary filling

· Cover filling (inserted into a prepared cavity in a

tooth = Filling in general)

· Temporary or long-life anchorage for coronas or filling in root channels

· Healing cements, e.g. dental zinc oxide eugenol

cement which is used as temporary sealing material having a anodyne , sedative and antiphlogistic effect upon oral disease

578Biocompatible materials - LV 308.106

Requirements for dental cements

� Good thermal, chemical and bacterial isolation

� No or low toxicity

� Low or no tissue irritating effects

� Mechanical strength

� Chemical resistance

� Good sealing and adhesion properties

� No or low electrical conductivity

� Low film thickness

� Adaptable colour, haze ...

� Good processability

� x-ray opacity

579Biocompatible materials - LV 308.106

ROOT CANAL FILLING MATERIALS

Root canal filling materials consist of

– tapered gutta-percha (right root) or

– silver (left root) (or titanium or polymer coated gutta-percha)points

in standard sizes that match the size of the files used.

The points are cemented in place with root canal sealer

that is usually a zinc oxide and eugenol preparation.

Root canal filling materials are used to fill previously

prepared root canals. They are a part of root canal, orendodontic, therapy.

www.free-ed.net/sweethaven/MedTech/Dental/DentMat/lessonMain.asp?iNum=fra0208

580Biocompatible materials - LV 308.106

Gutta-percha points are made from the refined, coagulated, milky exudate oftrees in the Malay peninsula. Gutta-percha is pink or gray in color. It issoftened by heat and is easily molded. When cool, gutta-percha maintains itsshape. Gutta-percha points are used as a root canal filling material.

Advantages(1) They have a high thermal expansion.(2) They do not shrink unless used with solvent.(3) They are radiopaque, conduct heat poorly, and are easy to remove from the root canal.(4) They may be kept sterile in antiseptic solution, are impervious to moisture, and are bacteriostatic (prevent the growth or multiplication of bacteria).

Disadvantages(1) They shrink when used with a solvent.(2) They are not always easy to introduce into the root canal.

www.free-ed.net/sweethaven/MedTech/Dental/DentMat/lessonMain.asp?iNum=fra0209

GUTTA-PERCHA POINTS

www.synca.com

581Biocompatible materials - LV 308.106

SILVER ROOT CANAL POINTS

The dentist has the option to use silver root canal points infilling a root canal.

Advantages(1) They are more easily inserted than gutta-percha points and they have all the same advantages.(2) Sight selection of silver points is easy because they come in the same sizes and tapers as standard root canal broaches and reamers.

Disadvantages(1) They are more expensive than gutta-percha.(2) They do not adapt to contours of the root canal.(3) They tend to corrode if subjected to body fluids.

www.free-ed.net/sweethaven/MedTech/Dental/DentMat/lessonMain.asp?iNum=fra0210

582

Dental impression

ZnO-Eugenol

paste,

Plaster

irreversible

Thermoplastic

compositon mass

e.g. Guttapercha,

Stent's, Kerr, Waxes

reversible

rigid

Polysulfide(Thiocols)

Polyether

condensation

crosslinked

addition

crosslinked

Silicones

Elastomers Alginate

irreversible

Hydrocolloids

reversible

flexible

Impression

materials

583Biocompatible materials - LV 308.106

Processing of ElasticImpression Materials – Volume Effects

� Curing shrinkage

� Thermal shrinkage

� Storage time dependent shrinkage

584Biocompatible materials - LV 308.106

Processing of ElasticImpression Materials – Volume Effects

(R. Marxkors/H. Meiners, 1993)

585Biocompatible materials - LV 308.106

Artificial teeth

www.trubyte.dentsply.com

586Biocompatible materials - LV 308.106

Artificial Teeth

Cut through a two-sectioned cuvette with embedded wax model on the functioning

model

Hard plasterMetal cuvette

Functioning model

Waxs model

(R. Marxkors/H. Meiners, 1993)

587Biocompatible materials - LV 308.106

Artificial TeethState of a thermoplastic material in dependence on the polymerisation

grade

degree of polymerisation

(R. Marxkors/H. Meiners, 1993)

588Biocompatible materials - LV 308.106

Artificial TeethProcessing

� Powder-liquid-technique: Pearl polymer: Monomer 2 : 1

Micrograph (grinded) of a Powder-Liquid Technique Polymerised Acrylate, Etched (75x)

(R. Marxkors/H. Meiners, 1993)

589Biocompatible materials - LV 308.106

Artificial TeethHot polymerisation

� Initiation by temperature increasing

� Heating by a water bath

� Residue monomer!

– Short time procedure:30 min heating, 30 min holding time at 100 °C

– Medium time procedure:60 min at 75 °C, 30 min at 100 °C

– Long time procedure:12 h at 50 °C, 2 h at 120 °C

(R. Marxkors/H. Meiners, 1993)

590Biocompatible materials - LV 308.106

Artificial TeethAuto polymerisation

� Initiation by reduction agent

� Faster than hot polymerisation procedure

� Use of very fine grained powder

� Continuous change in residual monomer content

(R. Marxkors/H. Meiners, 1993)

591Biocompatible materials - LV 308.106

Dental Implants

worldental.org/images

592Biocompatible materials - LV 308.106

Conditions

� „Biological system“

– State of the bone and the soft tissues

� i.e., height and width of the jaw bone: the higher and

thicker the better the conditions for a successful

implantation

� Width < 5 mm and height < 8 ... 10 mm are critical

dimensions because bone volume (mass) is to smallfor holding an implant

593Biocompatible materials - LV 308.106

Conditions

� Sufficient bone density

� Gums (or Gingiva) state:

– Healthy soft tissue support for the implantand the supra construction

� Position of the upper jaw in relation to the

lower jaw

– Deflection against ideal position can lead to

loadings that can not be compensated by thematerials and/or the design

594Biocompatible materials - LV 308.106

Caution!

– Implantation site in the upper jaw

The bone of the upper jaw flanks themaxillary sinus that is connected withthe nose

-> inflammation and implant loss if theimplant penetrates the mucousmembrane of the maxillary sinus

- Implantation site in the lower jaw

N. mandibularis locates along the sideof of the lower jaw

-> numbness in the lower lip and thechin if this nerve is injured during theoperation

Nervus

mandibularis Maxillary sinus

595Biocompatible materials - LV 308.106

Dental implants - Types

� Transosseous implants:– Only used in mandibles

– These implants are inserted in the jawbone, and penetrate thewhole jaw -> anchoring at the bottom of the chin by means of apressure plate

– Disadvantage: general anaesthesia owing to the extraoral surgicalapproach for placement -> longer hospitalisation; bone degradationaround the posts

– Materials: CoCr-alloys, CP Ti and gold

596Biocompatible materials - LV 308.106

Dental implants - Types

� Subperiostal implants:– These implants are inserted between the top of the jawbone (on-

the-bone) and the gum

– Long-time behaviour: the implants have to be replaced after someyears (in most of the patients) 5 years upper jaw, 10 years lower jaw

– Cause: chronic inflammation around the implant posts andloosening over time

� Inflammation -> bone degradation + support removal by surgery ->crater shaped damage of the jaw -> afterwards problems withremovable denture

597Biocompatible materials - LV 308.106

Dental implant - Types

� Endosteal (endosseous) implants:

– The implants are completely integrated in the jaw (feel and functionlike natural teeth)

– proper conditions of material selection, design and use ->Osseointegration = bone tissue grows around the implant andprovides anchorage

– most frequent dental implants today

Blade, disc, cylinder or screw implants from titanium or metalalloys with ceramic coating, ceramics

598Biocompatible materials - LV 308.106

Osseintegration

(J.B. Park, Bioceramics, 2008)

599Biocompatible materials - LV 308.106

Endosteal Implant Types

Lower jaw without teeth and applied

blade implant

Screw and cylinder implants (Ti)

www.implantat-wissen.de

www.3d-machining.com/3dmedicalspeciality.html

disc implant

osseosource.com/dental-implants

Customised ZrO2 dental implant in comparison

with a conventional implant. Dental Tribune

Austrian Edition, 12/2008, pp 9-12

www.bioimplant.at/index-

Dateien/BioImplantSurgeryVideos.htm

www.implantat-wissen.de

600Biocompatible materials - LV 308.106

Implant ComponentsImplant Components

www.dentalclinicdelhi.com/implants.htm

601Biocompatible materials - LV 308.106

Implantation

� 2 steps

– 1. Anchorage of the implant in the jaw followed by a healing phase

(≈ 4 month lower jaw, 6 month upper jaw)

– 2. Application of the superstructure system: crown, bridge, denture

www.implantat-wissen.de

www.implantat-wissen.de

602Biocompatible materials - LV 308.106

Implant solutions

www.commerceimplants.com/dental-implant-solutions.html