Partial Veneer Crowns

1. PREPARATIONS FOR
PARTIAL VENEER
CROWNS
Rani Ranabhatt
Department of Prosthodontics

2. CONTENT
INDICATIONS
CONTRAINDICATIONS
ADVANTAGES
DISADVANTAGES
ARMAMENTARIUM
POSTERIOR PARTIAL VENEER CROWNPREPARATION
 MAXILLARY PREMOLAR THREE QUARTER CROWNS
 MAXILLARY MOLAR THREE QUARTER CROWN
 MAXILLARY MOLAR SEVEN-EIGHTHS CROWN
 MANDIBULAR PREMOLAR MODIFIED THREE QUARTER CROWN
ANTERIOR PARTIAL VENEER CROWN PREPARATION
 MAXILLARY CANINE THREE QUARTER CROWN
 PINLEDGE PREPERATION ON MAXILLARY CENTRAL INCISOR

3. Introduction
• An extracoronal metal
restoration that covers only
part of the clinical crown is
considered a partial veneer
crown.
• An intracoronal cast metal
restoration is called an
inlay or an onlay if one or
more cusps are restored.

4. • Partial veneer crowns generally include all tooth
surfaces except the buccal or labial wall in the
preparation. Therefore, these restorations
preserve more of the tooth’s coronal tissue than
does a complete crown.

5. • Buccolingual displacement of the restoration is
prevented by internal features (e.g., proximal
boxes and grooves)
• Can be used as single tooth restorations or as
retainers for a fixed dental prosthesis (FDP).
• They can be used on both anterior and posterior
teeth
• Because they cover less of the coronal surface,
partial coverage restorations tend to be less
retentive than complete crowns and also less
resistant to displacement

6. INDICATIONS
1) Intact buccal wall & well supported by
sound tooth structure.
2) Teeth with crown length that is average or
exceeds average.
3) Teeth with normal anatomic crown form,
i.e. without cervical constriction.
4) Anterior teeth with adequate labio-lingual
thickness.

7. CONTRAINDICATIONS
1) High caries rate
2) In short clinical crown because retention may
not be adequate.
3) In endodontically treated teeth or non-vital
teeth
4) In teeth that are proximally bulbous
5) Deep cervical abrasion
6) Teeth with extensive core restorations
7) Bell shaped teeth (severe cervical constriction)
8) Thin teeth or restricted faciolingual dimension

8. ADVANTAGES
1) Conserves tooth structure.
2) Easy access to supra-gingival margins for
finishing.
3) Less gingival involvement than with complete
cast crown.
4) Aesthetics are superior to that of the complete
crowns.
5) Complete seating of the restoration can be easily
verified during cementation.
6) Reduced pulpal and periodontal insult during
tooth preparation.

9. DISADVANTAGES
1) Retention is less than that of complete veneer
crown
2) Skillful preparation is crucial to avoid metal
display
3) Preparation is limited to teeth with normally
shaped, average length clinical crown.
4) It is not indicated for use in cases of non vital
teeth

10. POSTERIOR PARTIAL VENEER
CROWN PREPARATION

11. • Maxillary premolar three-
quarter crown
• Maxillary molar three-quarter
crown
• Maxillary molar seven-eighth
crown
• Mandibular premolar modified
three quarter

12. MAXILLARY PREMOLAR THREE QUARTER
CROWNS
A. Occlusal reduction
B. Axial reduction
C. Groove placement
D. Bucco-occlusal contrabevel
E. Occlusal offset
F. Finishing

13. Occlusal reduction
Before any partial veneer crown preparation , mark
the proposed location of the margin of the completed
preparation on the tooth with a pencil.

14. Recommended minimum clearances for reduction
of a partial veneer crown preparation. Slight hollow
grinding of the lingual incline of the buccal cusp
results in an acceptable clearance with the least
display of metal.

15. Assess the amount of occlusal clearance in the
intercuspal position and in all excursive movements
of the mandible.

16. After verifying the alignment, remove tooth structure
between the guide grooves (with a smooth
continuous motion) and place a cervical
chamfer.
A periodontal probe placed in each groove should be
carefully viewed in both planes (mesiodistal and
buccolingual).
Axial reduction

17. Buccal wall are flared
to leave no
unsupported enamel
Occlusocervical height for a
proximal groove is 4 mm
Floor of the groove should be
flat and smooth, chamfer
extend cervically

19. As the cervical chamfer extends closer to the
cemento-enamel junction, more axial tooth structure
is removed. Consequently, the deepest portion of the
groove (its pulpal wall) will be located slightly closer
to the center of the tooth.

20. THREE QUARTER CROWN FOR
MAXILLARY MOLAR
Some additional leeway may exist for groove placement
because more tooth structure is present on molars than on
premolars. Also, because of their less prominent position in
the dental arch, molars are less visible.
As a result, the mesioproximal flare can sometimes be
extended onto the buccal surface without incurring esthetic
liability.

21. MAXILLARY MOLAR SEVEN-EIGHTHS
CROWNS
The seven-eighths crown preparation includes, in addition to
the surfaces covered by the three-quarter crown, the distal half
of the buccal surface.
Therefore the mesial aspect of this preparation resembles that
for a three-quarter crown; the distal aspect resembles that for
a complete crown
A. Occlusal reduction
B. Axial reduction
C. Groove placement, flaring, contrabevel

22. Occlusal reduction
Occlusal depth grooves
Mesial half of occlusal
reduction completed

23. Occlusal reduction
completed
Parallel guiding groove placed in the
lingual tooth surface

24. Groove placement, flaring, contrabevel
Proximal groove placed Buccal groove with flaring of the
mesial groove

25. Connect the two grooves with a smooth contrabevel that
follows the ridge of the mesiobuccal cusp.
Mesial groove is smooth and has a
90-degree cavosurface angle

26. MANDIBULAR PREMOLAR MODIFIED
THREE-QUARTER CROWN

27. 1. Additional retention is required because of the shorter
crown lengths of mandibular teeth. This can be
obtained by extending the preparation buccally,
although because of their rather prominent position in
the dental arch, these teeth should be modified only
distal to their height of contour.
2. The axial surface that is not prepared (the buccal)
includes the functional cusp. This means that additional
tooth structure must be removed to provide sufficient
bulk of metal for strength.

28. Occlusal reduction
Place 0.8-mm depth grooves on the buccal inclines of
the lingual cusp and 1.3-mm grooves on the lingual
inclines of the buccal cusp.
.

29. Axial reduction
1. Mesial is prepared as three-quarter and seven-eighth
crown.
2. Reduce the distal surface as for a complete crown,
extending the preparation to the transitional line angle
and onto the buccal surface. However, it should not
extend mesially beyond the middle of the distal half of
the buccal surface, and the chamfer should not extend
too far cervically;

30. Finishing
• the grooves of the three-quarter crown should be
slightly buccal. Care must be taken so that the distal
groove is slightly closer to the center of the distal wall
(so the distobuccal line angle will not be undermined).
Mesial and buccal groove

31. The chamfer must be heavy enough to allow 1.5 mm of
clearance in the area of occlusal contact. A regular or
thick diamond is used to place the chamfer, which
should connect the grooves and provide a protective
"staple" linkage of alloy in the completed restoration.

32. ANTERIOR PARTIAL VENEER
CROWN PREPARATION

33.  Maxillary canine three-quarter crown
 Maxillary central incisor pinledge

34. MAXILLARY CANINE THREE-QUARTER
CROWN
A. Incisal and lingual
reduction
B. Axial reduction and
groove placement
C. Incisal offset and
lingual pinhole

35. Incisal reduction Half lingual surface
reduction
Lingual reduction

37. Axial reduction Groove Flare
Proximal flare on
premolars and canines

38. Required interproximal
clearance

39. Incisal offset and lingual pinhole
Anterior partial veneer crowns require a means of
reinforcement for preserving the casting's integrity. For
an anterior tooth, an incisal offset or groove is needed to
create a band of thicker metal to provide a "staple"
configuration. This provides additional rigidity and
resistance against bending of the casting.

41. PINLEDGE PREPARATION
A pinledge is occasionally used as a single restoration,
generally to reestablish anterior guidance, in which case only
the lingual surface is prepared. More commonly, however, it is
used as a retainer for a fixed partial denture or to splint
periodontally compromised teeth.
.
Four unit FPD with modified
pinledge
Modified pinledge serving as a
retainer for a four unit FPD

43. Indication
1. undamaged anterior teeth
2. high esthetic requirement
3. prepared on bulbous teeth
4. to establish the desired anterior guidance.

44. Contraindication
1. Patients with poor oral hygiene or a high caries rate
2. Often it is not possible to place pinholes of adequate
size and length in teeth that are thin labiolingually.
3. Pinledges are contraindicated on non-vital teeth and
when the alignment of the abutment will conflict with
the proposed path of withdrawal of the fixed partial
denture.

45. A, Guiding grooves are placed for lingual reduction.
B, The lingual reduction is completed, and an incisal bevel
is placed.
C, Incisal and cervical ledges are prepared.
D, Indentations have been made.
E, Pinholes are prepared to a depth of 2 mm. The junction
between the ledge and the pinholes has been countersunk.

46. Ledges & Indentations
• Two ledges are prepared across the reduced
lingual surface. These provide room for
additional bulk of metal to ensure rigidity.
• Without them, the restoration would not be very
strong because it would consist of only a thin
sheet of metal.
• Recommended minimum ledge width is 0.7 mm.

47. • The ledges are prepared parallel to the incisal
edge of the tooth, as viewed from the lingual
aspect, and parallel to one another, as viewed
from the incisal aspect

48. MAXILARY CENTRAL INCISOR PINLEDGE
A. Conventional pinledge
B. Pinledge with
proximal slice
C. Pinledge with
proximal groove

49. Mesio-occlusal or Disto-occlusal
Inlays

50. Indications
• An inlay can be used instead of amalgam for
patients with a low caries rate who require a
small interproximal restoration in a tooth with
ample supporting dentin.
• It is among the least complicated cast
restorations to make and can be very durable
when it is done carefully

51. Contraindications
• Because these restorations rely on intracoronal
(wedging) retention, inlays and onlays are
contraindicated unless there is sufficient bulk to
provide resistance and retention form.
• MOD inlays may increase the risk of cusp
fracture and are generally not recommended.

52. Advantage
• Cast inlays and onlays can be extremely long-
lived restorations because of the excellent
mechanical properties of the gold alloy
• Unlike an inlay or amalgam, an onlay can
support cusps, reducing the risk of tooth
fracture.

53. Disadvantage
• In the restoration of a small carious lesion, an
inlay is not very conservative of tooth structure
• High occlusal force may lead to cusp fracture as
a result of wedging from the inlay.

55. Mesio-occluso-distal onlay

58. To summarise…
• Preparations for restorations should be based on
fundamental principles i.e a preparation must satisfy all
the three principles i.e biologic, mechanical & esthetic
principles which inturn are responsible for the success of
the prosthodontic treatment
• Also, it should be carefully decided which restoration to
choose based on each case.