complex restorations

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Transcript of complex restorations

PREPARE BY

Abu bakar siddik

city dental college

Dhaka

Complex Restorations:A. Cast Metal Restorations:

1.cast metal inlay restoration

2. Cast metal onlay restoration

3. Partial veneer crows

4. Full Veneer crows

B. Tooth Coloured Restorations:

1. Direct /Indirect composites

2. Ceramic Restorations

3. CAD-CAM based restorations

C. Inlay retained Bridges.

Cast Metal Restorations

Material used:

Casting alloys

Four distinct groups of alloys are used currently-

High gold alloys

Low gold alloys

Pallidium silver alloys

Base metal alloys

IndicationsLarge restoration

Endodontically treated teeth Teeth at risk for fracture Dental rehabilitation with cast metal alloys Diastema closure and occlusal plane corrections Removal prosthodontic abutment

Contra-Indications:

Small restorations Where esthetic is prime consideration because metal inlay, onlay display Metal

colour. Patient having high caries index. In young patient When patient can not come for second visit Where expected life of a tooth is short life of a tooth is short.

Advantage: Strengthens remaining tooth structure

More bio compatible with better tissue response.

Much more wear resistant than direct composite restoration.

control of contour and contact.

Disadvantages: Number of appointment and more chair time.

More expensive than direct restorations.

More technique sensitive

Repair is difficult

Esthetically not acceptable.

InlayDefinition:

An inlay is an indirect intracoronal restorations which is fabricated extra orally and cemented the prepared tooth. It is designed to restore occlusal and proximal surface of posterior teeth without involving the cusps.

Steps of inlay preparation

1.Tooth preparantion Occlusal outline form Proximal box preparations Resistance and retention form Placement of grooves Gingival bevels occlusal bevels Final cleaning, drying and inspection of the

cavity

2. Impression taking3. Die Making4. Wax patterns5. Investigate the pattern and casting

the mold6.Gold casting.

Gingival bevels

Proximal box

Prepared cavityOcclusal bevels

Occlusal outline Gingival bevels

Cast Metal Onlay

Definition:

It is the type of restoration which caps all the cusps of a posterior tooth can be thoughtfully designed to strengthen a tooth that has been weakened by caries or previous restorative experiences.

Steps of Onlay1. Tooth preparation- occlusal outline form proximal box preparation Cusp reduction Retention and Resistance form2. Impression taking3. Record of interocclusal relationship4. Temporary restorations5. Making cast6. Making die7. Wax pattern fabrication8. Sprucing 9. Washing of wax pattern10. Investing 11. Casting procedure.12. Cleaning of casting13.Trying in casting14. Cementations of the casting

Partial veneer crown(Three Quarter crown)

Definitions: It is the cast metal crown restoration that cover only a part of the

clinical crown mot commonly used type of partial veneer crown is ¾ crown. (Three Quarter).

Generally all tooth surface except buccal or the labial surface is not included in the preparation.

Uses: As a retainer for short span bridge. As a single restoration. As a splint in antirior teeth. posterior teeth-

Indication1. for posterior teeth Lost moderate amount of tooth structure with intact

and well supported buccal surface. Retained for fixed partial denture.2. For anterior teeth- Suitable for teeth with a sufficient bulk. Retainer for F.P.D or splinting of anterior teeth.

Contra-indications: Short clinical crows

High carries index

Extensive destruction

poor alignment.

Thin teeth

long span bridge

Non vital teeth

Advantages Conservative of tooth structure Easy access of margins Less gingival involvement than complete crown Easy escape of cement and good sealing Electrical pulp test is possible complete sealing of the crown can be easily seen by direct observation

Disadvantages Less retention and resistance than complete cast crown limited adjustment can be done in the path of withdrawn Possibility of showing metal specially in the lower anterior and

posterior teeth. Possibility of recurrent caries more Difficult in preparation compared of other types of crown restoration.

Full Veneer Crown

Definitions:

Full veneer crown is described as “ A restorations that covers all the coronal tooth’s surfaces’’.

Indication: On teeth that exhibit extensive coronal destruction. On Non-esthetic zone teeth with extensive restorations. Show clinical crowns Retainer for a long span fixed partial denture On endodontically treated tooth. Incase of generalized attrition where vertical dimension is

reduced.

Contra-indications: It treatment objectives can not be met with a more

conservative restorations. Extensively restored or cariously involved teeth within

esthetic zones. Protect the coronal integrity of a natural tooth.

Advantages:

Greater retention and resistance than a more conservative restoration.

Strength is superior to that of other restoration.

Permit easy modification of occlusion.

Protect the coronal integrity of a natural tooth.

Disadvantages:

Pemoval of the tooth structure is extensive and can have adverse effect on the periodontics.

It is longer feasible to perform electric vilality testing of the abutmnt teeth.

Tooth preparationArmantentariom: Handpiece

Round ended tapered diamond

171 L bur

Torpedo diamond

Torpedo bur

Short needle diamond

Red utility wax.

Procedure: Placement of round ended tapered diamond bur approx 1 mm deep in

central, mesial & distal fossae. And creating about 1.5 mm of clearance on the functional cusps and 1 m on the non functional cusps.

Place these grooves in the buccal & lingual developmental grooves & in each triangular ridge extending from the cusp tip to the centre of its base.

On the non functional cusp, the groove should parallel & should be slightly flatter to ensure additional reduction of the functional cusp.

Con…

Place depth orientation grooves for functional cusp bevel across the facial occlusal line angle of the mandibular premolar or molar and across the lingual occlusal of maxillary tooth.

Round ended tapered diamond is used to give bevel parallel to the inward facing inclines of the opposing tooth at a depth of 1.5 mm.

Complete the occlusal reduction in two steps.

Half of the occlusal surface is reduced first so that other half will bemaintained as Refarance.

After completing the occlusal reduction the clearance can be checked by the patient to close on a 2mm thick strip of red utility wax.

Tooth colored Restorations:Tooth colored inlay and onlay

Indirect composite Inlay and onlay

Tooth colored restoration which are fabricated out side the oral cavity are called as indirect tooth coluredrestoration.

Indication: 1. Large detects

2.When more esthetics required.

Contra indication: 1. Heavy occlusal forces

2. Diffulty in mature control

3.Deep subgingival preparation.

Advantages: Less chair side time required due to laboratory fabrication Much more wear resistant than direct composite restoration. Show less polymerization shrinkage. More biocompatible with better tissue response Achieve better contacts and contours Strengthen remaining tooth structure. Extra oral polishing is easy.

Disadvantages: Required more number of patient appointment. Highly technique sensitive Restoration requires high level of operation skill There is need for temporary restoration More expensive than direct composite.

Steps in fabrication:

The indirect composite restoration is initially formed on a replica of the prepared tooth

The composite is built up in layers polymerizing each layer with a brief exposure to a visible light curing unit.

After it is built of full contour the restoration is coated with a special get to block out air and thus prevent formation of O2inhibited layer.

Final curing is accomplished by inserting the inlay into an oven like device that exposes the composite to additional light and heat.

The cured composite inlay is trimmed finished & polished in the laboratory.

Ceramic Inlay and Onlay Restoration

A ceramic inlay fits with in the contours of the tooth is cemented to the remaining tooth structure.

A ceramic onlay fits within the contours of the tooth and covers part or all the occlusal surface needed to be restored

Indications: When esthetic is main concern Patient having good oral hygiene status. Suitable of large preparation. When accessibility and isolation of tooth are easy to achieve When there is no excessive undercuts.

Contra- Indications: In patient with poor oral hygiene. Patient with multiple active caries Because of their brittle nature, they are contra-indication In case with minimal tooth los When moisture control is difficult to achieve. In case of excessive attrition of teeth Inadequate enamel for boning.

Advantages: Excellent esthetic. Low thermal conductivity Long lasting chemically inert low coefficient of thermal expansion Biocompatible nature

Disadvantages: More expensive than amalgam or composite. Require special and expensive laboratory equipment. Takes two appointment. Intra Oral finishing and polishing is a time consuming procedure. Fragile and brittle. Abrasive to the opposing enamel Highly technique sensitive.

Fabrication of Ceramic Inlay /Onlay

• It involves impression taking either with rubber based material or alginate.

• Ceramic restoration is fabricated using any one of following techniques.

Firing .Pressing CastingMachining.

The finished and glazed ceramic inlay /Onlay is etched with hydrofluoric acid and luted onto preparation using dual cure resin cements.

Ceramic crowns:

Indications: In area with a high esthetic requirement where a more

conservative restoration would be inadequate. In tooth with proximal or facial caries that can not be restored

with composite resin. In teeth with sufficient coronal structure to support the

restoration specially in incisal area.

Contra-indications: When a more conservative restoration can be used In posterior teeth with increased occlusal load. If occlusal load is unfavorable If sufficient enamel is not present to provide ad equable support.

Advantages: Excellent esthetics

Translucency similar to that of natural tooth structure.

Biocompatibility.

Disadvantages: Reduced strength of the restoration due to absence of

inforcing metal substructure.

Require more tooth cutting.

Difficult to achieve well fitted margin in some cases.

Can not be modified once prepared.

These restorations are not effective as retailers for a fixed partial denture.

Tooth preparations

occlusal reduction

Facial reduction

Lingual reduction

Chamfeil preparation

Finishing.

CAD –CAM based Restorations

CAD This type of restoration is made by the use a computer aided design (CAD) and computer aided manufacturing. (CAM) Process.

–CAM based Restorations.

Advantages: Time saving procedure. High quality High esthetics High strength. Minimum voids in restoration.

Disadvantages: Marginal gap of about 52 micron (min 25 micros) is

present. Minimum staining can be applied extremely. castle procedure.

Tooth Preparetion Similar to conventional indirect ceramic onlay restoration

occlusal aspect reduced to 2 mm for clearance.

All cavosurface margins are prepared to bolt joint (900)

Bevels and chamfers are avoided.

Computer Assisted design (CAD) A dry field for proper scanning with precision

Tooth preparation is scanned using intra oral camera optical impression.

Tooth surface coated with reflective medium for better computer assisted machining (CAM)

Computer Assisted Machining (CAM) Software designs the restoration, transferred to milling

Unit.

Milling unit has a dimond disk and cylindrical dimond to cut the ceramic block.

Try in and cementation: Removed from milling unit.

Ceramic restoration is etched and silanated

Luted using dual cure resin cement.

Inlay- Retained bridges:Indications: Abutment teeth with filings Replacing 1 or 2 teeth in the premolar, molar region- Metal ceramic All ceramic Fiber reinforced composite

Contra-Indications: Pontic Span too large Excessive parafunctions clinical crown too short weakened periodontium Occlusal anomalies abutment teeth felting poor oral hygiene

Advantage: Less destructive to tooth structure

cavities , filling involved in preparation

Good esthetics

Fixed restoration

Marginal fishing line easy to clean.

Disadvantage: Only 1 or 2 missing teeth short pontic span

Pin Retained Restorations

Definition: A pin remained restorations is defined as any

restoration which requires the placement of pin in dentin in order to provide sufficient retention ad resistance form to the restoration..

Indications: Badly broken teeth Badly broken nonvital tooth which required endodontic

treatment. Extended preparations Foundation for full coverage restorations\ Extensive class-V restorations Time period and cast factors.

Contra-Indications: When patient has occlusal problems When esthetics is connected When direct restoration is not possible because of Functional or anatomical consideration.

Advantage: conservation of tooth material Resistance and retention from increases Number of appointments one appointment is requited for pin

restoration Pin amalgam restoration is relatively inexpensive as compared to

cast restoration.

Disadvantages:Use of pin is teeth can causes dentine fracture. Compressive strength is not increase by use of pin. Using bur or pin in wrong direction can causes perforations. If pin ends appear on or near to the surface of the restorations it

may cause result in microleakage around the pins. sometime it is difficult to achieve optimal contours and occlusal

contacts with these restorations.

Materials for retentive Pins: Pins are available in different shapes, size s and material

such as stainless steel . Platinum –Palladium ,Platinum Irridium, Plastic, aluminum and acrylic.

Types of pins:

1 Indirect Pins

2 Direct Pins

1.Indirect Pins / Parallel Pins :

Cast Gold Pins

Wrought Precious Metal Pins

2.Direct Pins / Non Parallel Pins :

Cemented Pin Friction-locked Pin Self-threading Pin (TMS)

Principals and technique of pin placement:1. Cavity preparation for pin amalgam restoration: carrying out the tooth preparation by excavating carious dentin and

removing weakened tooth structure. Prepare facial and lingual walls parallel Pulpal and giving walls

perpendicular to axial wall Making of dovetails grooves boxes wherever required. Reduce cusp 1.5 -2 mm having the shoulder finish. Whenever possible margins should be kept supragingival.2. Pulp Protection- After preparation apply base or liner for pulp protection.3. Preparation of pin hole- pin holes are prepared using twist drills usually kodex drill. Drill is made of high speed steel that is swaged into aluminum shank. Drill performs cutting when rotated clockwise at slow speed suggested

speed-300 to 500 rmp to 1000 rpm. Omni-depth gauze is used to measure accurate dept of pinhole

Mark the point where pin is supposed to be placed. Penetrate a small round bur at low speed upto half of its diameter. This will make pilote hole or lead hole which allow accurate positioning of twist drill.

Direct the drill towards desired location of pin placement

When cutting dentin. Apply slight pressure.

After pin preparation is complete, confirm the depth using omni depth gauge and take a radiograph.

4. Pin banding and rimming.

5. Matrix placement.

6. Carving of amalgam.

7. Carving of amalgam

8. Removal of the matrix.

9. Finishing and polishing procedure-

Polishing must be done after 24 hours of restorations placement.

Factors Affecting retention of pin in tooth structure: Pin diameter Pin number Pin type Pin depth in dentin Cementing agents Association between pin channel and pin circumferences.

Factors affecting retention of pins in restoration materials: Pin length Pin Number Pin diameter Pin orientation Pin shape Interpin distance Pin restoration interphases Surface characteristics Bulk of material surrounding the pin.

Causes of Failure of pin Restoration:

1. Within the restoration Restoration may fracture because of improper

condensation, trituration, or manipulation.

2. Within Pin- Pin fracture may occur because of improper pin

placement.

3. At pin restoration interface:

Restoration may pull away from pin because of corrosion produces of pin restoration interface.

4. At pin tooth interface:

Pin may separate along with restoration because of improper pin tooth joint.

5. Within tooth: Dentinal fracture can occur because of concentrations of internal etress

because of improper selection of pin according to dentin type.

6. Broken drills: Drill may break in the following conditions- stress is applied laterally during drilling. Dull drills are used. Drill is stopped while entering or existing from the tooth.

7. Loose pins- Loose pin can occurs in the following conditions- Repeated insertion Pin drill is rotated more than required Pin hole is too large. Manufacturer’s discrepancy.