classification of dental cements - vowi.fsinf.at · elastomers alginate irreversible hydrocolloids...
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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.
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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
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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
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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
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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
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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
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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
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Processing of ElasticImpression Materials – Volume Effects
� Curing shrinkage
� Thermal shrinkage
� Storage time dependent shrinkage
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Processing of ElasticImpression Materials – Volume Effects
(R. Marxkors/H. Meiners, 1993)
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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)
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Artificial TeethState of a thermoplastic material in dependence on the polymerisation
grade
degree of polymerisation
(R. Marxkors/H. Meiners, 1993)
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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)
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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)
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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)
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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
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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
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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
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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
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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
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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
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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
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Implant ComponentsImplant Components
www.dentalclinicdelhi.com/implants.htm
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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