Prostho Veneer Restorations and Radicular Retained Restorations

Fixed Prosthodontics Restoration

  1. PFM (Porcelain Fused to Metal Crown)

  2. All Ceramic Crown (aka Porcelain Crown, Ceramic Crown)

  3. Metal Crown (aka Stainless Steel Crown, Shell Crown)


Partial Veneer Restoration

  1. Three-quarter crown

  2. Pin modified three-quarter crown

  3. Seven-eighths crown

  4. Porcelain laminate veneer

  5. Proximal half crown


Intracoronal Restorations

  1. Inlays

  2. Onlays


Radicular Retained Restorations

  1. Dowel Post and Core

  2. Pre-fabricated Post and Core


COMPLETE VENEER RESTORATIONS


PFM

  • Widely used

  • Consist of: complete coverage cast metal crown, layed fused porcelain 

  • Least conservative


Indications

  • Esthetics

  • Porcelain crown contraindicated

  • Gingival involvement


Contraindications

  • Large pulp chamber

  • Intact buccal wall

  • Feasible more conservative retainer


Advantage

  • Superior esthetics


Disadvantages

  • Removal of substantial amount of tooth structure

  • Subject to fracture (porcelain brittleness)

  • Difficulty to obtain accurate occlusion

  • Difficult shade selection

  • Inferior esthetics vs porcelain crown


All Ceramic Crown

  • Most esthetically pleasing

  • Resembles natural tooth structure better

  • Susceptible to fracture


Fabrication Techniques

  • Platinum Foil Matrix Technique - old technique, adapted to die

  • Direct Firing - associated with previous tech., die is removed through air abrasion

  • Lost Wax - most recent technique


Historical Background of Crowns and Inlays

  • C.H. Land - first ceramic crowns and inlays (1886), platinum foil matrix (1887)

  • Acrylic Resin in 1940s, causing ceramic restorations to decline in popularity until disadvantage of resin materials was realized

  • Vacuum firing was introduced, improving the appearance of the ceramic restoration. More dense and translucent restoration is achieved, impossible for airfiring.


Introduction of High Strength Porcelains

  • Developed due to incidence of fracture in old ceramic restorations.

  • Two paths:

    • Two ceramic materials to fabricate the restoration (high strength, non-esthetic core + low strength, esthetic ceramic)

    • Ceramic materials that combine good esthetics with high strength ceramics


High Strength Ceramic Core

  • Introduced in Dentistry by McLean and Hughes (1965)

  • Glass-alumina composite is used instead of feldspar

  • Fused aluminum oxide particles are much stronger, acting as a constraint model


Indications

  • High esthetics

  • Proximal caries

  • Intact incisal edge

  • Endodontically treated (w/ post and core)

  • Favorable distribution of occlusal load


Contraindication of High Strength Ceramic Core

  • Superior strength is warranted

  • Significant caries with sufficient coronal tooth structure

  • Thin teeth faciolingually

  • Unfavorable distribution of occlusal load


Advantages

  1. Esthetics unsurpassed

  2. Good tissue response

  3. Conservative of facial wall



Disadvantages

  1. Reduced strength (vs PFM)

  2. Proper preparation EXTREMELY CRITICAL

  3. Among least conservative restoration

  4. Brittle

  5. Single restoration only


Complete Cast Crown

  • Badly damaged posterior teeth

  • Single tooth or as a retainer

  • Adequate tooth structure removal to allow restoration to its original contour

  • Reduction should be sufficient to produce acceptable strength


Advantages

  • Greater retention and resistance (vs partial veneer crown)

  • Superior strength

  • Can modify the axial tooth contour (dealing with malaligned teeth)

  • Allows modification for proper placement of survey lines, guide planes, and occlusal rests

  • Easy modification of the occlusion on supraerupted teeth


Disadvantages

  • Extensive reduction of the occlusal

  • Common incidence of inflammation of gingiva

  • Electric vitality test no longer feasible

  • Objections to display of metal


Indicators

  • Extensive coronal destruction

  • Maximum retention and resistance OR high displacement force is anticipated

  • Support a removable partial denture

  • Endodontically treated teeth


Contraindications

  • More conservative restoration

  • Need for high esthetics


PARTIAL VENEER RESTORATIONS

Partial Veneer Crown (POSTERIOR)

Indication

  • Sturdy clinical crown of average length OR longer

  • Intact buccal surface not in need of contour modification

  • No conflict between axial relationship of tooth and proposed path of withdrawal


Contraindications

  • Short teeth

  • High caries index

  • Poor alignment

  • Bulbous teeth

  • Thin teeth


Advantages

  • Conservative of tooth preparation

  • Easy access to margins for finishing (dentist), for cleaning (patient)

  • Less gingival involvement than with complete cast crown

  • Easy escape of cement and good seating

  • Easy verification of seating simple

  • Electric vitality test feasible


Disadvantages

  • Slightly less retentive than complete cast crown

  • Limited adjustment of path of withdrawal

  • Some display of metal


Partial Veneer Crown (ANTERIOR)

Indication

  • Same as posterior PVC

Contraindication

  • Same as posterior, additional:

    • Nonvital teeth

    • Extensive destruction

    • Cervical caries

Advantages

  • Same as posterior

Disadvantages

  • Same as posterior, additional:

    • Non-indicated on non-vital teeth


Porcelain Laminate Veneer

History

  • 1983 - introduction

    • Combined esthetics and positive tissue response of porcelain with adhesive strength of acid etched retained restoration

  • Acid Etching

    • Retention is accomplished by creation of microporosites in the porcelain and enamel

    • Treated with 10% acid solution (hydrofluoric acid)

      • Normally used phosphoric acid

  • Silane Coupling Agent

    • Function: alter the surface of a solid, increase the shear strength of porcelain-composite resin bond

  • Composite Resin Luting Cements

    • Auto-curing composite resins retain laminate veneers

    • This kind of luting cement increases working time


Advantages

  • Excellent esthetics

  • Excellent long term durability

  • Inherent porcelain strength

  • Marginal integrity

  • Soft tissue compatibility

  • Minimal tooth reduction


Disadvantages

  • Time

  • Cost

  • Fragility

  • Lack of repairability

  • Difficulty in color matching

  • Irreversibility

  • Inability to trial cement the restoration


Indications

  • Correcting diastemata

    • Exception: anything more than 2 mm of diastema causes the PV to be unsupported

  • Masking discolored or stained teeth

  • Masking enamel defects

  • Correcting misaligned or malformed teeth


Contraindications

  • Bruxism

  • Short teeth

  • Insufficient or inadequate enamel

  • Large restoration OR endodontically treated teeth

  • Oral habits causing excessive stress on restoration

GINGIVAL FINISHING LINES

Chamfer - preferred for all gingival finishing lines.

  • Supragingival finishing lines - same advantages as proximal finishing lines

  • Impressions are easier to make

  • Major disadvantage - visible staining or color changes


INCISAL PREPARATION

  1. 1 mm of porcelain thickness

  2. Only 0.5 mm of incisal reduction is required if incisocervical of restoration is 0.5 mm longer than existing tooth.

  3. Only rounding off of incisal edge is required if preoperative teeth are to be lengthened by 1 mm.

  4. Finishing line should slope slightly gingival approximately 75 degrees from the labial.


LABIAL DEPTH REDUCTION

  • 0.5-0.7 mm  - maxillary teeth

  • 0.3 mm for smaller teeth (mandibular incisors)

  • Instrument: three-tiered depth cutter;

    • To not overproduce and affect the dentinal portion


INLAYS

  • Walls diverge occlusally

Class I Inlay

  • Occlusal bevel - provides marginal integrity

  • Wall - provides retention and resistance

  • Pulpal floor - provides resistance


Class II Inlay 

  • Gingival bevel - marginal integrity

  • Proximal box - retention, resistance; structural durability

  • Proximal flare - marginal integrity

  • Isthmus - retention and resistance, structural durability

  • Dovetail - retention and resistance, structural durability

  • Occlusal bevel - marginal integrity


Class III Inlay

  • Proximal box - retention and resistance, structural durability

  • Dovetail - retention and resistance

  • Facial bevel - marginal integrity

  • Proximal flare - marginal integrity

  • Isthmus - retention and resistance

  • Lingual bevel - marginal integrity


Class V Inlay

  • Pinholes - retention and resistance

  • Peripheral wall -retention and resistance

  • Bevel - marginal integrity


Onlay

Class II MOD

  • Involves the tip of the cusp

  • Gingival bevel, occlusal lingual bevel, occlusal facial bevel, proximal flare - marginal integrity

  • Proximal box, Isthmus - retention and resistance, structural durability

  • Planar occlusal reduction, Functional cusp bevel, occlusal shoulder - structural durability


Radicular Retained Restoration

Treatment Planning

  • Extensive caries or periodontal disease make removal of teeth more sensible than endodontically treating it.

  • Orthodontic repositioning or root resection may also restore it.

  • This should be done if its loss will significantly jeopardize the patient’s occlusal function. 


Inspection

  • Assessment of a tooth for endodontic treatment:

    • Good apical seal

    • No sensitivity to pressure

    • No exudate

    • No fistula

    • No apical sensitivity

    • No active inflammation


Considerations

  • Endodontically treated teeth are believed to be weaker than the vital teeth. 

  • Metal post replaces the root canal filling to strengthen it.


Disadvantages

  • Placing a post needs additional operative procedure

  • Preparing the tooth to accommodate the post needs removal of additional tooth structure

  • Difficulty of restoration of the tooth later (post may have failed to provide adequate retention)

  • Complicates or prevents future endodontic retreatment


Considerations (for posterior teeth) 

  • Endodontically treated posterior teeth are subject to greater loading. 

    • They are positioned closer to the insertion of the masticatory muscles, combined with morphologic characteristics.

  • Complete coverage is recommended with a high risk of fracture.

    • Best protection as the tooth is encircled by the restoration.


Types

  1. Dowel post and core (custom)

  2. Prefabricated post


Classification of prefabricated posts

  1. Tapered smooth sided post

  2. Tapered serrated post

  3. Tapered threaded post

  4. Parallel smooth sided

  5. Parallel serrated post

  6. Parallel threaded post


Principles of Tooth Preparation

  1. Conservation of Tooth Structure

    1. Root canal  - creates a post space, minimal tooth structure removal; over enlargement of removal may perforate or weaken then split the tooth during cementation of the post.

    2. Coronal tissue - lost from caries, previous restorations or preparation for endodontic access cavity; further reduction is needed for cast core; amount of remaining tooth structure is probably the single most important predictor of clinical success

Six Features of a Successful Design Preparation

  • Adequate apical seal

  • Minimum canal enlargement

  • Adequate post length

  • Positive horizontal stop

  • Vertical wall

  • Extension of the final restoration onto the sound tooth structure


  1. Retention Form

    1. Anterior teeth - affected by preparation geometry, post length, diameter, surface texture, luting agent; long posts with circular cross section for good retention and support

    2. Posterior teeth - has curved roots and elliptical ribbon shaped canals, short posts on divergent canals for better retention

    3. Retention of a post is affected by the following:

      1. Preparation geometry -  nearly circular cross section, canal with elliptical cross sections to ensure adequate retention and eliminate undesired undercuts

      2. Post length - post length increases, retention increases; short post will fail, long post can damage apical seal OR cause root perforation

      3. Post diameter - increasing diameter is not recommended

      4. Post surface texture - serrated OR roughened post is more retentive

      5. Luting agent - has little effect on post retention

        1. Zinc phosphate and GI have similar renentive properties

        2. Polycarboxylate and composite resin - less

        3. May be important if post has poor fit within the canal.


      1.  

Three Stage Operation for a Post and Core Preparation (Direct Method)

  1. Canal preparation

  2. Acrylic Pattern Fabrication

  3. Finish and Cementation of Dowel Core


Canal Preparation

  1. Round bur - used to remove caries, bases, and previous restorations

    1. Prepare teeth for a complete restoration

    2. Not necessary to remove all supragingival coronal tooth structure

  2. Removal of endodontic filling material:

    1. Warmed endodontic plugger

    2. Rotary instrument

    3. Make the post length equal to the height of the anatomic crown (or two-thirds the length of root). 

    4. Leave some of the gutta percha on the apex (master apical cone) that provides an apical seal

  3. Preparation of keyway

    1. No. 170 bur -  key way at the occlusal where there is the greatest bulk

    2. Keyway should cut to the diameter of the bur approx. 1mm

    3. Keyway should cut to the length of the cutting blades of the bur approx 4mm

  4. Placing contra-bevel

    1. Prominent contra bevel around the occlusal external periphery of the preparation with a flame diamond

      1. Provides a gold collar around the occlusal circumference of the preparation

      2. Retention and prevention of fracture (resistance) 

      3. Safeguard on a precision fitting dowel (tendency to exert lateral force when cemented)


Acrylic Pattern Fabrication

  1. Sprue fitted into the canal

    1. 14 gauge solid plastic sprue OR matchstick

    2. Cut a small notch on the facial portion of the occlusal end of the plastic sprue; to aid in orienting the dowel core pattern

  2. Mix acrylic resin monomer and polymer to a runny consistency

    1. Lubricate the canal with a petrolatum on a small piece of cotton on the reamer

    2. Fill the mouth of the canal as full as possible with acrylic resin

    3. Coat the plastic sprue with monomer

  3. Completely seated in the canal

    1. Make sure that the external bevel is covered

    2. Pump the pattern in and out when acrylic resin has initial set to prevent locking into any undercuts

  4. Relubricate the canal and reseat the acrylic post after polymerization

  5. Make a second mix of acrylic resin, place it around the exposed plastic sprue

    1. Coronal portion can be molded on the labial and lingual during the curing of the acrylic

  6. Acrylic core is shaped following the outline form of a jacket preparation.

    1. No roughness or undercuts.

    2. Finished acrylic pattern should be smoothened.


Cementation of Dowel Core

  • Luting agent should fill all dead space.

    • Voids may cause for periodontal inflammation via laterla canals.

  • Rotary past filler (or cement tube) is used to fill the canal with cement.

  • Post and core is inserted gently to reduce hydrostatic pressure, may cause root fracture

  • Groove should be placed along the side post to allow excess cement to escape (if a parallel side post is being used)


Location of Dowel Core for Posterior Teeth

  1. Maxillary premolars with two canals utilize the buccal canal for most of its restoration

  2. Maxillary molars utilize the palatal canal for retention

  3. Mandibular molars utilize the distal canal