Partial Veneer
Crowns , Inlays
and Onlays
Anterior Partial Veneers
 A partial veneer has been described as a
restoration covering two or more surfaces of a tooth.
 There are three types of partial veneer crowns:
1. Three quarter crown
2. Seven eight crown
3. Mesial half crown
All other forms of partial veneers are
considered variations of the three basic types.
 Three quarter crown – covers three surfaces of the
crown leaving one surface intact.
 Seven eighth crown – used in maxillary molars and
premolars. It encompasses seven eighth the
gingival circumference of the tooth.
 Mesial half crown – is a three quarter crown
rotated 90o, preserving the distal surface of the
tooth. This preparation design is primarily
indicated for the distal retainer of a mandibular
FPD with a tilted molar abutment.
Indications For Partial Veneers:
1) Intact or minimally restored teeth.
2) Teeth with crown length that is average or exceeds
average.
3) Teeth with normal anatomic crown form, ie,
without cervical constriction.
4) Anterior teeth with adequate labio-lingual
thickness
Contra-indications:
1.
2.
3.
4.
5.
6.
7.
High caries rate
Short teeth
Non vital teeth
Deep cervical abrasion
Teeth with extensive core restorations
Bell shaped teeth (severe cervical constriction)
Thin teeth
Advantages:
► Conserves tooth structure
► Easy access to margins for finishing (for dentist)
► Less gingival involvement than with complete cast
crown
► Aesthetics are superior to that of the complete
crowns
► Electric pulp testing can be done on the intact
surface
► Complete seating of the restoration can be easily
verified.
Disadvantages:
 Retention is less than that of complete veneer
crown
 Skilful preparation is crucial to avoid metal display
 Preparation is limited to teeth with normally
shaped, average length clinical crown.
 It is not indicated for use in cases of non vital teeth
Steps for Preparation of Tooth for Partial Veneer
Crowns
There are seven steps for tooth preparation for partial
veneer crowns:
1. Occlusal or Incisal reduction
2. Lingual reduction
3. Inter-proximal reduction
4. Proximal box or Groove placement
5. Occlusal or incisal offset placement
6. Facial bevel
7. Finishing the preparation
 The technique for each step may vary according to
whether the tooth is in the maxilla or in the mandible.
In the following discussion the tooth that is being
considered is the maxillary canine.
Armamentarium:
• Narrow (0.8mm) round tipped , tapered diamond –
For bulk reduction
• Regular size (1.2mm) round tipped tapered diamond
or carbide – Finishing
• Wheel shaped diamond - Bulk reduction
• Tapered and straight carbide fissure burs preparation of boxes, ledges and pinhole finalisation.
• Small round carbide bur
• Finishing stones
• Inverted cone carbide bur – preparation of incisal
offset
1 ) Incisal Reduction:
 Depth orientation grooves are placed at about 1 –
1.5mm depth.
 Using tapered round ended diamond bur reduce
the incisal edge 1mm at 45o to the long axis of tooth.
Follow the facial contour of the tooth And
uniformly remove 1 – 1.5mm of enamel
 Design of incisal bevel should prevent contact with
opposing teeth and incisal margin
2) Lingual Reduction:
Accomplished in two stages:
a. Lingual surface reduction –
 Depth orientation groove placed
 Football or wheel shaped diamond bur used to
reduce lingual surface.
 Slight ridge left running incisogingivally along the
centre of the lingual surface.
 Clearance with opposing tooth is atleast 0.7 – 1mm
 Do not over reduce cingulum
b. Lingual gingival reduction • Using tapered round ended diamond, a chamfer of 0.5mm
deep is made at the cervical finish line.
• Reduction parallels long axis of the preparation (in this case
the incisal two thirds of the labial surface)
 The path of placement of the restoration must be
accurately determined before axial reduction
 Mesiodistally it should be parallel to the long axis of the
tooth , buccolingually , it should parallel the middle third or
incisal third of the tooth.
 to enhance the retention and resistance form, a slightly
exaggerated chamfer is placed in the lingual aspect and a
guiding groove is placed in the middle of the lingual surface
3) Inter proximal reduction: Three steps are involved ;
a) Using a 169L carbide bur, reduce the proximal surface by
moving bur from lingual to the facial surface. Position bur
so that the tip of the bur is further facial than the shank. Do
not break contact with the adjacent teeth. The facial line
angles must remain intact to provide aesthetically pleasing
results
b) Using a narrow chamfer diamond, establish a light chamfer
finis line on the proximal surface
a) Using a hatchet instrument, the contact with the adjacent
tooth is broken to establish labial proximal extensions. A
flame shaped bur is used to finish the flare. Axial reduction
is now complete
4) Proximal grooves:
These are placed as far labially as possible without
undermining the labial enamel plate
First groove is begun by cutting a 1mm deep template
with a 170L bur. This groove is extended gingivally in
increments to the full length.
Second groove is cut parallel to the first on the
opposite side.
Lingual wall of the groove has a 2 – 5 degree incisal
convergence with the lingual gingival wall of the
preparation.
Facial wall of the groove should be continuous with the
proximal flare to contribute bulk to the facial margin.
The grooves are parallel to the incisal half or two
thirds of facial surface.
Boxes may be used as substitutes for the grooves
where there are existing proximal restorations or
caries. Boxes must be narrow to resistant, hence
lingual wall of the box shortens as it moves lingually.
The grooves are a minimum of 3mm long and
terminate within 0.5mm of the gingival finish line.
5) Incisal groove
 Using 37 inverted cone bur, develop a 0.5 to 1mm
groove connecting the proximal groove . This
should be in the dentin and parallel to the DEJ.
 Groove is not placed at the expense of the incisal
edge.
6) Facial bevel:
Using a fine, flame shaped diamond bur, develop a
narrow bevel < 0.5mm on the labioincisal finish line at
right angles to incisal two thirds of the facial surface.
7) Finishing the preparation
Using a carbide finishing bur, round the angles to
ensure continuity of all the finish lines
Features of anterior three quarter crown preparation
Pin Modified Three Quarter crown
Indications:
Undamaged anterior teeth in caries free mouth
Alteration of lingual contour of the maxillary
anterior teeth or the alteration of occlusion
Anterior splinting
Contra – indications:
Large pulp
Thin teeth
Non vital teeth
Carious involvement
Problems with proposed path on withdrawal of FPD
Advantages:
Minimal tooth reduction
Minimal subgingival margins, hence periodontally
preferable
Optimum access for margin finishing and hygiene
Adequate retention
Disadvantages:
Less retentive than complete coverage
Alignment can prove difficult
Technically demanding
Not usable on non vital teeth
Pin ledge preparation
Three designs of pin ledge preparations have been
describes:
1- Conventional Pin ledge involving only the lingual
surface of the tooth
2 - Pin ledge with proximal slice
3 – Pin ledge with a proximal groove
Conventional pin ledge preparation
 Lingual reduction –
This is done similar to conventional anterior
two third crown preparation with a few additional features. A
lingual incisal bevel is prepared with a wheel bur , about
1.5mm in width. It should be parallel to the uncut incisal edge
and should end lingual to the labio-incisal angle to avoid
display of metal.
The lingual axial wall should be parallel to the
gingival two thirds of the labial surface. The chamfer finish
line should stop lingual to the contact of the tooth surface
adjacent to the edentulous space inorder to improve
accessability to operator and patient (for maintenance)
 Proximal reduction –
Only one proximal surface is prepared.
The proximal surface adjacent to the edentulous
ridge is only prepared. The diamond is held either
parallel to the path of placement or slight lingual
inclination is given. The primary purpose of this step
is to provide adequate bulk of the metal in area for
subsequent connector. Reduction includes contact
area , but should not be extended too facially.
 Ledge preparation –
Two ledges are prepared across
the reduced lingual surface. The provide room for
sufficient bulk of metal to ensure rigidity. The ledges
are prepared parallel to the incisal edges of the tooth,
as viewed from the lingual aspect and parallel to each
other as viewed from the incisal aspect.
Indentations are made in the two
sides of the incisal ledge and slightly off centre of the
cervical ledge to prevent pulp exposure when the
pinholes are placed.
 Pinhole preparation Sink pilot channels using small
round bur or a small twist bur. The depth of the
completed pinhole should be about 2mm. Enlarge
and deepen the pilot channels with a tapered bur
when the placement and orientation of the pilot
channels have been found to be satisfactory. Bevel
the junction between the pinhole and the ledge with
a round bur slightly larger than the largest diameter
of the pinhole. Inspect all areas of the preparation for
smoothness and evaluate the margins
Features of pinledge anterior three quarter crown