dental materials chapter 1

intracoronal restorations are used

to repair damage that is restricted to the internal parts of the tooth

• damage of this nature is usually caused by caries, but occasionally caused by trauma

cavity preparation

used when prepping the teeth for intracoronal restoration

• removes diseased or damaged tissue and creates a space that is accessible for restoration and able to stably retain the restoration

cavity preparations may be restored with

• resin composites

• amalgam

• cast alloys

• ceramics

• less often by gold foil

when would an extracoronal restoration be necessary?

when damage to the tooth is extensive and an intracoronal restoration is not feasible.

extracoronal restoration tooth preparations

much more aggressive than intra and nearly always must be restored using restorations that are fabricated indirectly

ex. crowns, onlays, veneers

indirect fabrication

restoration created outside of the patients mouth and then cemented later on

direct fabrication

restoration created inside of the patients mouth without the need of cement

what do extracoronal restorations typically require?

a model or die of the surgically prepared tooth be made.

• die must be extremely accurate in size, detail and relationship to adjacent teeth

• made by taking impressions

• more recently models of teeth can be digitally required

fabricating a restoration on a die may involve using

waxes, casting alloys, polymers, ceramics or a combination of these materials

CAM techniques

computer-aided machining techniques may be used to fabricate indirect or direct restorations

what ultimately depends on the strength and ability of the restorative material to withstand oral forces

the design of the preparation and restoration

in endodontic treatment

the space created when pulpal tissues are removed must be replaced with sealers that prevent ingress of bacteria

• restoration of the coronal portion often requires extracoronal restorations but may use intracoronal on anterior teeth

post and buildup

depending on the amount of tooth structure lost and extent of damage due to disease ot trauma a post and buildup may be placed in the root canal to strengthen the tooth and aid in fabrication of the final restoration

a partial denture/ bridge is prepared

by placing extracoronal restorations on teeth adjacent to edentulous space = called abutment teeth

artificial replacement teeth = pontics

bridges are always prepared using

indirect techniques and are fabricated from alloys, alloy ceramic combos or ceramics alone

the tooth structure of abutment teeth on traditional bridges

is heavily sacrificed regardless of condition of the tooth

due to this an alternative technique called resin-bonded fixed partial (maryland bridge) is sometimes used if abutment teeth are healthy and free of major restorations

maryland bridge

an extracoronal crown is not required on the abutment teeth. “arms” from the pontic are bonded to the enamel of the abutment teeth via resin-based cement

• retention of these is poorer than traditional bridges, and cannot always be used due to inappropriate occlusion or positions of abutment teeth

bridges can also be placed using implants

both abutments must be implants and the bridge is screwed or cemented on

endosseous dental implants

increasingly used to replace missing teeth

• placed into bone with special techniques to ensure integration with bone, and then indirect restorations are placed on implants

• bone quality must be sufficient to hold an implant

dental implants

fabricated from special titanium-based alloys or ceramics

• leave adjacent teeth unrestored and allow easy cleaning for the patient

• problem is the expense

removeable partial

indicated for when multiple teeth are missing in multiple locations

• also common in situations in which there is no distal abutment tooth available to anchor a fixed bridge

use a framework of a stiff alloy that rests on specific abutment teeth and distributes occlusal biting forces evenly and appropriately to remaining teeth

• advantageous to pt for cleaning and inspection of remaining teeth — though generally less esthetic and less comfortable

complete denture

indicated for complete loss of teeth

• fabricated with acrylic polymer bse with acrylic teeth bonded into positions compatible with patients opposing arch

• some can be held in place with implants by screws or special abutments and is very successful in lower arch, though requires more meticulous home care and is not cost effective

fluoride gels, rinses and varnishes are highly effective at preventing caries

some fluorides have been incorporated into direct esthetic filling materials

sealants

if teeth have deep fissures and pits that are at high risk for decay, they are highly effective at reducing development of caries

• tenaciously bonded to tooth enamel via acid-etching procedures

mouth protectors

made of polymers that absorb the energy of facial bloes and prevent this energy from affecting the teeth and facial structures

• night guards prevent premature wear from occlusal trauma, referred to as parafunction

a small lesion in an anterior tooth would most likely be restored with which of the following materials?

resin composite

a direct restorative material used to restore a small portion of an anterior tooth should have which of the following properties

esthetics

an intracoronal restoration may be fabricated from which of the following materials?

all of the above

a direct restorative material used frequently to restore a portion of a posterior tooth that is subject to large biting forces would possess which of the following properties

high strength

a full crown on the maxillary anterior tooth may be restored with which of the following restorative materials

ceramic and gold-based alloy

complete denture bases are usually made from which of the following materials

acrylic resins

acrylic resins are used in which of the following types of restorations

complete denture bases

which of the following materials is most commonly used for dental implants

titanium-based alloys

a posterior restoration that involves the occlusal surface and 2 proximal surfaces including all cusps is called

MOD

a restoration that covers the entire coronal portion of the tooth is called a

crown

after root canal procedure the canal is frequently filled using

gutta percha

a restoration that replaces a missing tooth that is supported by and cemented to two adjacent fully restored teeth is called

bridge or fixed partial denture

a restoration in which artificial teeth are mounted on a metal framework containing clasps that attach it to remaining abutment teeth is called a

removeable partial denture

a restoration that replaces all the teeth in the upper or lower arch with artificial teeth that are attached to a plastic base is called a

complete denture

a restoration that replaces the root of an extracted tooth and is stabilized by bone growth around it is called an

implant or endosseous implant

_________ materials used to prevent damage to the teeth and oral bone from trauma

polymer

when the tooth ia surgically modified to eliminate destruction inflicted by caries, extent of damage determines the type of restorative strategy and material used.

if damage is restricted to internal parts of the tooth the surgical preparation modifies the tooth for an

intracoronal restoration and the remaining tooth structure retains the restoration

extracoronal restorations sometimes use

pinholes or slots to help retain the restoration

if restoration replaces a missing tooth, preparations must be designed so that the restoration fits inside the remaining teeth

intracoronal restorations are generally used to repair the internal structure of teeth but may involve some external surfaces as well

mostly fabricated directly onto the tooth with:

• amalgam

• gold foil

• cast gold

• composite

amalgam margins

initially good, but deteriorate over time — usually after many years

longest lasting restorative materials

gold foil and ceramics

shorter service lives — restorative materials

composites and glass ionomers

extracoronal restorations involve at least some of the axial structure of the tooth

• most are fabricated indirectly — away from the tooth

• most common form today is a crown

crowns

may be fabricated entirely from alloy or may have an alloy substructure supporting a ceramic veneer

ex. ¾ crowns and onlays in which one or more tooth cusps are restored

ceramics may also be used for crowns

in endodontics, how are the pulp canals prepped

• the canals are identified, shaped and cleaned using nickel-titanium files

• shaped canals are then sealed with a natural or synthetic polymer.

  • sometimes sealing material is extruded beyond the root apex

• once sealed, canal openings are sealed using a resin composite

  • a steel post may be cemented in place with resin polymer and the tooth is built back to full contour with amalgam or resin composite

• tooth is then surgically prepared for a crown, impression is taken, a model made and crown is fabricated of alloy or ceramic

• crown is then cemented with a glass ionomer or resin-based cement

bridges are fabricated from

casting alloys or a combo of alloy and ceramic — the allot serves as the substructure/strength

• more recently ceramics like zirconia have been used — in all-ceramic bridges, high strength ceramic is used as the substructure followed by a veneer that is all zirconia (monolithic)

endosseous implants are increasingly used to

manage the restoration of missing teeth and have reduced the need for bridges and partial dentures

for endosseous implants, in some cases when missing one or few teeth

the implant is placed to the level of the bone and an alloy-ceramic restoration shapes the gingiva and stores the missing space

• a screw may be used to retain restoration

for endosseous implants, in other cases, multiple implants are used to restore an entire arch of missing teeth

the implant is placed to a level just above the tissue

• multiple screws retain the denture

removable partial dentures should be removed

for the patient to clean, as well as clean remaining teeth

acrylic night guards

controls forces that a patient can apply to any one tooth; distributes forces a number of ways and is soft enough that it wears down rather than the teeth