dr saransh malot partial veneer presentation preparation and classification

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PARTIAL VENEER CROWNS : preparation and classification

Dr Saransh MalotDept of Prosthodontics


Content• Introduction• Types• Indications• contraindications• Advantages • Disadvantages• Armamenteriam• Maxillary posterior ¾ crown• Mandibular posterior ¾ crown• Anterior ¾ crown• 7/8 crown• Proximal half crown• Pin ledge


Types of partial veneer crowns:-

For posterior teeth

1. ¾ crown ( three quarter).2. Modified ¾ crown.3. 7/8 crown

For anterior teeth

1.¾ crown ( three quarter).2.Pin ledge.


INDICATIONS

used to restore posterior teeth that have lost moderate amounts of tooth structure.

used as retainers.Anterior partial veneers can be used

as retainers, to reestablish anterior guidance, and to splint teeth.

suitable for teeth with sufficient bulk.


CONTRAINDICATIONS: Teeth with short clinical. Contraindicated as retainers for long

span bridges. Rarely suitable for endodontically

treated teeth (esp. anterior). In dentitions with active caries and /

or periodontal disease. In teeth that are proximally bulbous. In poorly aligned teeth.


ADVANTAGES:

Tooth structure is spared.

reduced pulpal and periodontal insult

during tooth preparation.

Much of the margin is accessible to the

dentist for finishing and to the patient for

cleaning.


Less restoration margin is in proximity to the gingival crevice lowering the possibility of periodontal irritation.

An open faced partial veneer crown is more easily seated completely during cementation while a full veneer crown tends to act like a hydraulic cylinder containing a viscous fluid.

ADVANTAGES:


With some of the margins visible,

complete seating of a partial veneer

crown is more easily verified.

If an electric pulp test ever needs to be

conducted on the tooth a portion of

enamel is un-veneered and accessible.

ADVANTAGES:


Less retention and resistance than full coverage crowns.

Preparing a tooth for this kind of treatment is difficult primarily because only limited adjustments can be made in the path of withdrawal.

DISADVANTAGES:


The placement of grooves, boxes and pinholes requires dexterity from the operator.

Some metal is displayed in the completed restoration which may be unacceptable to patients with high cosmetic expectations.

DISADVANTAGES:


ARMAMENTARIUM • Narrow (approximately 0.8 mm), round-tipped, tapered diamond.• Regular-size, (approximately 1.2 mm), round tipped,tapered

diamond• Football-shaped or wheel-shaped diamond• Tapered and straight carbide fissure burs• Small, round carbide bur• Small-diameter twist drill• Inverted-cone carbide bur• Finishing stones• Mirror. • Explorer and periodontal probe• Chisels


MAXILLARY POSTERIOR ¾ CROWN


OCCCLUSAL REDUCTION:

• Make depth orientation cuts with ROUND –END TAPERED DIAMOND BUR on the triangular ridges and major developmental grooves of occlusal surface.

• Recommended range being 1-1.5 mm with 1.5 mm on the functional cusp.


FUNCTIONAL CUSP BEVEL

It should extend from the central groove on the proximal surface around to the central on the other proximal surface

Begin the functional cusp bevel by placing three to five depth orientation grooves 1.5 mm deep using a ROUND END TAPERED DIAMOND and NO. 171 BUR. The bur is held at 45 degrees to the long axis of the preparation.


LINGUAL AXIAL REDUCTION

While reducing the lingual surface with a TORPEDO DIAMOND be careful not to over incline the lingual wall.


PROXIMAL AXIAL REDUCTION

• SHORT NEEDLE- Breaking of contact TORPEDO DIAMOD- Reduction.

• As the axial reduction is done, a CHAMFER finish line is formed. This also serves as a guide to producing adequate axial reduction.

The removal of tooth structure near the finish margin should equal to one half of the diameter of the diamond or 0.5 mm.


PROXIMAL GROOVES

TAPERED FISSURE BUR: They are directed to the opposite lingual corner of the tooth forming a lingual hook. Must be cut along a line parallel with a line tangent to the outermost curvature of the tooth.

They must be placed as FACIALLY AS POSSIBLE without undermining the facial enamel. They should parallel the long axis of the tooth


The groove as far gingivally as possible ending about 0.5 mm above finish line.

The proximal groove should have a definite LINGUAL WALL (retention to lingual tipping). Directed toward the middle of the tooth at right angles to the outer surface of the tooth ( prevents undermining of facial enamel and avoids sharp unsupported wings of tooth structure).

The distal groove should be cut so that it parallels the mesial groove.


OCCLUSAL OFFSET

• tapered fissure bur.

• It is a 1.0 mm wide ledge or flat terrace on the lingual incline of the facial cusp. It connects the grooves and assuming the shape of an inverted ‘V’.

It helps in casting rigidity by tying together the proximal grooves to form a reinforcing staple.Finish it with a end cutting bur


FACIAL BEVEL

• FLAME DIAMOND AND TAPERED FISSURE BUR

• Place a narrow occlusal finish bevel of 0.5mm width along the occlusofacial line angle taking care to keep it perpendicular to the path of insertion

The bevel, both flares and the chamfer should connect smoothly to form one continuous finish line without sharp angles.


MANDIBULAR POSTERIOR ¾ CROWN


1.Planar occlusal reduction

2. Functional cusp bevel

3.Occlusal shoulder


4.Lingual axial reduction

5. Proximal axial reduction.

6.Axial finishing.


7. proximal grooves

8.Proximal flare

9.Facial bevel


ANTERIOR ¾ CROWN

1. Lingual reduction

2. Incisal reduction

3. Lingual axial reduction


4. Proximal reduction

5. Proximal finishing

6. Proximal grooves


7. Proximal flare

8. Incisal offset

9. Incisal bevel


7/8 th CROWN • Planar reduction

• Functional bevel

• Facial lingual axial reduction

• Complete axial reduction


• Proximal finishing.

• Proximal grooves.

• Proximal flare.

• Occlusal offset

• Occlusal finishing and bevel


PROXIMAL HALF CROWNS

• Typical indication of proximal half crown


• Occlusal planar reduction

• Functional cusp bevel

• Mesial axial reduction

• Lingual and facial axial reduction


Occlusal isthmus and countersink

• Occlusal isthmus:- bulk , rigidity and retention

• Countersink :- near distal fossa . Supplement retention resistance and bulk.


• Facial and lingual grooves

• Distal occlusal offset

• Flare and occlusal bevel


Pin ledge modified anterior partial veneer crown

• 3 grooves :- 1st more mesial .

2nd more lingual.

3rd shorted and near opposite side cingulam

(MUST BE PARELLEL)


• Ledges and offset


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dr saransh malot partial veneer presentation preparation and classification

Health & Medicine

powerpoint templates

tooth preparation

modified crown

posterior teeth

anterior teeth

lingual surface

lingual axial reduction

removal of tooth structure