1. PREPARATIONS FOR PARTIAL
VENEER CROWNS
Presented by:-
Himanshu khatri
B.D.S. Final year
Department Of
Prosthodontics

2. CONTENT
INDICATIONS
CONTRAINDICATIONS
ADVANTAGES
DISADVANTAGES
ARMAMENTARIUM
POSTERIOR PARTIAL VENEER CROWN PREPARATION
 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. 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.

4. 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

5. 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. DISADVANTAGES
1) Retention is less than that of
complete veneer crown
2) Skilful 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

7. Armamentarium
• Narrow(0.8 mm) round-tipped tapered diamond
(regular or coarse grit)
• Regular size(1.2mm)rounded-tipped tapered
carbide
• Wheel shaped diamond bur
• Tapered and straight carbide fissure burs
• Small round carbide bur
• Small-diameter twistdrill
• Inverted-cone carbide bur
• Finishing stones
• Mirror
• Explorer and periodontal probe
• chisels

8. POSTERIOR
PARTIAL
VENEER
CROWN
PREPARATION

9.  Maxillary premolar three-quarter
crown
 Maxillary molar three-quarter crown
 Maxillary molar seven-eighth crown
 Mandibular premolar modified three
quarter

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

11. Occlusal
reduction (i)
Before any partial veneer crown preparation , mark the
proposed location of the margin of the completed preparation
on the tooth with a pencil.
Mark location with pencil

12. (ii)
Place depth grooves for the occlusal reduction. These should
be made with a tapered carbide or narrow diamond in the
developmental grooves of the mesial and distal fossae and on
the crest of the triangular ridge. In the central groove they
should be slightly less (about 0.2 mm) than 1 mm deep to
allow for finishing; on the centric (lingual) cusp they should be
slightly less than 1.5 mm deep in the location of the occlusal
contacts.
Minimum clearances for reduction

13. (iii)
Place three depth grooves on the lingual incline of the buccal cusp.
Initially, these should be kept somewhat shallow as they approach
the buccal cusp ridge. In the area of occlusal contact, the groove
should be about 0.8 mm deep so that there will be at least 1 mm of
clearance after finishing.
Additional guiding grooves placed
(on the lingual cusp)

14. (iv)
Verify groove depth with a periodontal probe. When this is found to
be acceptable, remove the islands of tooth structure remaining
between the grooves
Occlusal reduction

15. (v)
Assess the amount of occlusal clearance in the intercuspal position
and in all excursive movements of the mandible.
Common error is insufficient reduction

16. (vi)
Grinding a small concavity on the incline of the buccal cusp may
help obtain sufficient clearance while maintaining the original
occlusocervical dimension of the buccal tooth surface.
Occlusocervical dimensions
Interproximal clearance relative to adjacent teeth

17. Axial reduction
(vii)
Place grooves for axial alignment in the center of the
lingual surface and in the mesiolingual and distolingual
transitional line angles. These should be parallel to the
long axis of the tooth and should not exceed half the
width of the tip of the diamond used to place them.
Because the path of withdrawal of a partial veneer is
critical, assess these grooves carefully when correction is
still possible.
A common error is to incline the path of withdrawal
toward the buccal. This either reduces retention or leads
to an excessive display of metal.

18. After verifying the alignment, remove tooth structure between the guide
grooves (with a smooth continuous motion) and place a cervical
chamfer.
Carry the diamond into the proximal embrasure and reduce the proximal
wall.
(viii)
A periodontal probe placed in each groove should be carefully viewed in
both planes (mesiodistal and buccolingual). It often helps to pour an
irreversible hydrocolloid (alginate) impression in fast-setting plaster and to
evaluate the cast with a dental surveyor, particularly if multiple partial
veneers are being used as retainers for an FPD.
Axial reduction

19. (ix)
After verifying the alignment, remove tooth structure between the guide
grooves (with a smooth continuous motion) and place a cervical
chamfer.
Carry the diamond into the proximal embrasure and reduce the proximal
wall.
For proper reduction of the axial tooth surface, it is important to
understand the factors that determine correct positioning of the proximal
groove. A proximal groove is placed parallel to the path of withdrawal.
Normally, unsupported tooth structure will remain on the buccal side of
the groove, and this side is flared to remove it. illustrates the relationship
among the initial axial reduction, groove placement, and location of the
cavosurface angle where the flare meets the intact buccal wall. The
cavosurface angle is especially significant when preparing a tooth for a
partial veneer that should display a minimum of metal; the further to the
buccal the margin
is, the more gold will be visible.
Groove is placed perpendicular to the prepared
surface

20. (x)
A subtle but extremely important variable that determines the final location of
the cavosurface angle is the apical extension of the preparation. 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.
This results in a flare that can extend farther onto the facial or buccal surface
than desirable. Marking the location of the intended facial flare on the tooth
with a pencil before initiating the proximoaxial reduction is helpful. The
intersection of this mark with the reduced occlusal surface is a convenient
reference point.
Distal proximal reduction is stopped prior to breaking
proximal contact

21. Stop the proximal reduction well short of the pencil mark and usually
slightly short of breaking the proximal contact .
The resulting flange should be parallel to the linguoaxial preparation, with
the chamfer placed sufficiently cervical to provide at least 0.6 mm of
clearance with the adjacent tooth and the axial wall allowing for a proximal
groove of at least 4 mm of length occlusocervically.
Buccal wall are flared to leave no
unsupported enamel

22. Groove placement
(xi)
Preparation of the proximal grooves is best done with a tapered carbide bur.
Position the bur against the interproximal flange parallel to the path of
withdrawal and make a groove perpendicular to the axial surface. The
groove need not be deeper than 1 mm at its cervical end but may be deeper
near its occlusal end.
During this stage, the bur must be held precisely parallel to the selected
path of withdrawal.
Floor of the groove should be flat
and smooth, chamfer extend
cervically
Occlusocervical height for a
proximal groove is 4 mm

23. The criteria that need to be met consist of the following:-
The grooves should resist lingual displacement of a periodontal probe or
explorer.
The walls of the grooves should not be undercut relative to the selected
path of withdrawal.
The walls should be flared toward the intact buccal surface of the tooth
Allowing it to tip axially will result in excessive taper between opposing
proximal grooves, which is a common error.
Buccal aspect of the groove has been
adequately flared

24. Depending on available access, it may be feasible to complete the flaring
with the same rotary instrument that was used to place the groove.
However, removing the last lip of unsupported tooth structure with a chisel
is often a better option, because this minimizes the risk of damage to the
adjacent tooth.
Initial preparation of the mesial
groove
Initial flaring Remove all
unsupported enamel

25. Buccalocclusal contrabevel
(xii)
Connect the mesial and distal flares with a narrow contrabevel that follows
the buccal cusp ridges. This can be placed with a diamond, a carbide, or
even a hand instrument. Its primary purpose is to remove any unsupported
enamel and thereby protect the buccal cusp tip from chipping during
function.
The bevel should remain within the curvature of the cusp tip rather than
extend onto the buccal wall. This will result in a convex shape of the
restoration, and light will be prevented from reflecting back to a casual
observer. Thus the restoration will be less obvious, and the outline form of
remaining buccal enamel will be perceived as the shape of the tooth.
Buccocclusal contrabevel remains within the curvature of the
cusp tip

26. Occlusal offset
If additional bulk is needed to ensure rigidity of the restoration, it can be
provided with an occlusal offset. This V-shaped groove extends from the
proximal grooves along the buccal cusp. It is not usually necessary for
posterior partial veneer crowns but is essential for the structural durability of
anterior partial veneer crowns.

27. Finishin
g
Round all sharp internal line angles to facilitate subsequent procedures.
A fine-grit diamond or carbide can be used to blend the surfaces.
Re-evaluate the flares, paying particular attention to any remaining
undercuts, which must be removed.
The flares should be straight and smooth, with sufficient clearance
between them and the adjacent tooth.
A minimum clearance of 0.6 mm is recommended.
The mesial flare cannot extend beyond the transitional line angle.
However, because the distal margin is less visible, it may extend slightly
farther to the buccal, allowing better access for oral hygiene.

28. THREE QUARTER CROWN FOR
MAXILLARY MOLAR
The principles used in a premolar preparation also apply for a maxillary
molar.
However, 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.

29. 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

30. The mesial half of the buccal tooth surface remains intact and is protected
by a narrow contrabevel or chamfer similar to the one used in the three-
quarter crown preparation.
A distal groove may be placed, although generally this is not necessary. A
groove in the middle of the buccal surface is placed parallel to the path of
withdrawal. Distal to this groove the buccal surface is reduced in two
planes, cervical and occlusal, with the cervical paralleling the path of
withdrawal and the occlusal following the normal anatomic contour.
The lingual surface of the tooth also is reduced in two planes, and centric
cusp bevels are incorporated.

31. Occlusal reduction
Upon completion of the occlusal reduction, adequate clearance should exist
in all excursive movements of the mandible. Minimum measurements are
the same as for the three-quarter crown preparation.
Place depth grooves in the central and developmental grooves as well as
on the crests of the triangular ridges. To delineate the extent of the lingual
centric cusp bevel, they should extend onto the lingual surface of the tooth.
On the lingual incline of the mesiobuccal cusp they will resemble depth cuts
for the three quarter crown preparation. On the distobuccal cusp they
should be approximately 0.8 mm deep to provide sufficient occlusal
clearance for this non-centric cusp.
Occlusal depth grooves

32. Remove the tooth structure between the depth grooves. Concave shaping
of the resulting mesiobuccal incline may again prove useful because it will
permit the occlusocervical height of the cusp to be maintained. When
completed, this bevel should provide 1.5 mm of clearance in the intercuspal
position as well as throughout all excursive movements of the mandible.
Mesial half of occlusal reduction
completed
Occlusal reduction completed

33. Axial reduction
Place three alignment grooves in the lingual wall and transfer the selected
path of withdrawal to the distobuccal transitional line angle area, where a
fourth alignment groove can be placed.
Start the reduction in the middle of the lingual surface. The mesial half is
prepared like a three-quarter crown and the distal half like a complete
crown.
Carry the facial reduction sufficiently mesial to include the buccal groove.
Although the occlusal half of the buccal surface of maxillary molars is
rather flat, some additional reduction may be necessary in the occlusal
third. This follows the normal anatomic configuration of the tooth and often
resembles a small version of the centric cusp bevel. If correctly
performed, the reduction will allow for contouring of the restoration so that
when viewed from the mesial, the distal half of the restoration is hidden
behind the mesiobuccal cusp. A frequent error is to over taper the buccal
wall segment, with resulting loss of retention.
Parallel guiding groove
placed in the lingual tooth
surface

34. Groove placement, flaring,
contrabevel
Prepare the mesial groove like the three-quarter crow.
Place the buccal groove parallel to the mesial groove and perpendicular to
the buccoaxial wall. Often it is not necessary to flare the buccal groove
because the flat configuration of this area of the tooth precludes any
unsupported enamel after the groove is placed. The buccal groove should
resist mesiodistal displacement of a probe.
Proximal groove placed Buccal groove with flaring of the mesial
groove

35. Connect the two grooves with a smooth contrabevel that follows the ridge
of the mesiobuccal cusp.
This bevel should meet the same criteria as described in the three-quarter
crown preparation. Adequate clearance must be established interproximally
upon completion. All surfaces are finished to the same specifications as the
preceding preparations.
Mesial groove is smooth and has a 90-degree cavosurface
angle
Seven-eight crown
preparation

36. MANDIBULAR PREMOLAR
MODIFIED THREE-QUARTER
CROWN
Mandibular partial veneer preparations are made more often on premolars
than on molars. They differ from maxillary molar three-quarter crown
preparations in two respects:
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.
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.

37. 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.
These guiding grooves are once again placed to follow the basic groove
and fissure pattern of the occlusal surface. Only one depth cut needs to be
placed to accommodate the functional cusp bevel on the distal aspect of
the distal ridge.
Reduce the occlusal surface by removing the tooth
structure between the grooves.
Depth holes Guiding grooves
Occlusal reduction

38. Axial reduction
Place guiding grooves on the lingual surface to parallel the proposed path
of withdrawal and the long axis of the tooth.
Prepare the mesial as already described for the three-quarter and seven-
eighth crown.
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;
otherwise, the distobuccal line angle will be unnecessarily reduced, which
would decrease the resistance form.
Axial reduction

39. Finishing
The modified three-quarter crown preparation can include two or three
grooves.
Place the mesial and buccal grooves as described for the seven-eighths
crown. Another distal groove may be placed. In general, to gain as much
length as possible, 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

40. Connect the mesial and buccal grooves with a centric cusp chamfer after
the grooves and mesial flare have been placed and evaluated.
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. Insufficient tooth
reduction where this chamfer meets the mesial flare is a common error.
Finally, all prepared surfaces are smoothed and the internal line angles
rounded.
Width of the chamfer on the centric cusp

41. ANTERIOR
PARTIAL
VENEER
CROWN
PREPARATION

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

43. The three-quarter crown on a maxillary canine is probably one of the most
demanding of all tooth preparations. As with such preparations on other
teeth, on a maxillary canine it involves the proximal and lingual surfaces
and leaves the facial surface intact. However, the greater degree of
difficulty stems from the different shape of the canine tooth. Unless the
placement of grooves is determined very precisely in advance, there will be
an undesirable display of metal in the interproximal embrasures . The
relatively short proximal walls do not allow much correction after initial
groove placement. Similarly, the greater degree of curvature in each
proximal wall immediately adjacent to the contact area significantly
influences the location of the preparation's facial margin
MAXILLARY CANINE THREE-
QUARTER CROWN
A. Incisal and lingual reduction
B. Axial reduction and groove placement
C. Incisal offset and lingual pinhole

44. Incisal and lingual reduction
Remove enough enamel to allow 1 mm of metal thickness. The design
of the incisal bevel should prevent contact between opposing teeth and
the incisal margin. However, the original configuration of the facial
surface should be preserved without significant incisal reduction of the
tooth. Outlining the anticipated location of the margin with a pencil can
be helpful.
Place depth grooves for both the incisal bevel and the lingual reduction.
The direction of the bevel may vary some what depending on the
configuration of the tooth. Generally it will make an angle of
approximately 45 degrees with the long axis of the tooth.
Incisal reduction

45. After the depth has been verified, perform the reduction. A football or wheel
shaped diamond bur is used to reduce the concave lingual wall.
The lingual reduction should not extend onto the cingulum itself, which will
be prepared as part of the axial reduction.
The lingual reduction should not extend onto the cingulum itself, which will
be prepared as part of the axial reduction.
Lingual surface reduction Half lingual surface
reduction
Wheel shaped
diamond bur
Lingual reduction

46. Axial reduction and groove
placementThe path of withdrawal of the restoration must be accurately determined
before axial reduction. Mesiodistally it should parallel the long axis of the
tooth; buccolingually it should parallel the middle third or incisal two thirds
of the facial surface. This will permit the preparation of proximal grooves of
optimum length in an area of the tooth where sufficient bulk is present.
To enhance the retention and resistance form of the preparation, place a
slightly exaggerated chamfer on the lingual aspect of the tooth and a
guiding groove in the middle of the lingual wall. When alignment has been
verified, the axial reduction can be performed in the same manner as the
other preparations.
Axial reduction – mesiodistally the bur is oriented
parallel to the long axis of the toothHalf axial reduction
Regular grit diamond
bur

47. It is important to understand the difference between this phase of the
preparation on a canine, with little bulk of lingual tooth structure as
opposed to a premolar or molar. After completion, a proximal flange
should result that will guide the rotary instrument during groove
placement.
The technical aspects of the preparation of proximal grooves are like those
described for the other partial veneer preparations. The primary difference
is the direction in which the groove is prepared.
Axial reduction Groove Flare
Axial reduction Completed axial reduction

48. Because the groove is placed perpendicular to the proximal wall, its deepest
portion will be slightly labial to the proximal flange that results when
proximo-axial reduction is completed. As a result, the proximal flares will
extend slightly farther onto the facial surface. This is even more accentuated
by the curvature of the proximal wall. Meticulous assessment of the needed
extent of the initial axial reduction is a prerequisite for successful
preparation.
Required interproximal
clearance
Proximal flare on premolars and
canines
Proximal
grooves

49. Incisal offset and lingual
pinhole
Anterior partial veneer crowns require a means of reinforcement for
preserving the casting's integrity. Posterior three-quarter crowns usually do
not need as much additional reinforcement because the solid "corrugated”
occlusal surface provides rigidity. 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.
Three quarter crown preparation

50. Connect the mesial and distal grooves with an incisal offset. It should
improve the general resistance form of the preparation against lingual
displacement and should have a V configuration. Sufficient dentin must be
preserved facially to the offset to prevent the metal from being visible
through the translucent tooth enamel. This is most effectively
accomplished with an offset that is slightly narrower labiolingually than
incisocervically.
The offset should follow the normal configuration of the incisal edge, and
its transition into the proximal flares should be smooth and continuous. An
inverted-cone diamond or carbide can be used to prepare the offset.
Place a pinhole in the cingulum area slightly off center to improve the
retention and resistance form of this preparation.
Preparation of incisal offset / faciolingual inclination of the rotary
instruments
Inverted cone carbide bur

51. The pinhole is prepared in five stages:
first, a small horizontal ledge is made with a large, tapered carbide bur;
second, a slight "dimple" is created with a round bur at the intended pinhole
location;
third, a pilot hole is prepared with a small-diameter twist drill (it must be
parallel to the precise path of withdrawal of the restoration);
fourth, the preparation is completed with a tapered carbide bur to a pinhole
depth of approximately 2 mm;
finally, a larger, round bur is used to countersink or bevel the junction between
pinhole and ledge.

52. PINLEDGE PREPARATIONA 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.
In these cases, one or more of the proximal surfaces are included in the
preparation design to accommodate the required connector(s). Retention
and resistance are provided primarily by pins that extend to a depth of 2
mm into dentin. Compared to other retainers, the pinledge preparation is
very conservative of tooth structure.
The preparation steps themselves are not difficult, but advance planning and a
thorough understanding of the various steps are prerequisites to success.
Diagnostic preparation on an accurate cast is particularly useful during the
planning phase.
Four unit FPD with modified pinledge Modified pinledge serving as a retainer for a four unit
FPD

53. Preparation of a number of parallel pinholes with a common path of
withdrawal can be intimidating. With some practice, however, this can be
accomplished freehand by most operators, especially when a tapered bur
is used.
Paralleling devices are available for practitioners who do not feel
comfortable preparing multiple pinholes. Generally, pinledges are highly
esthetic restorations. Plaque control after treatment is easier because of
short margin length and largely supragingival margin location.
Tapered bur
Pinledge splints

54. Indication
The pinledge is indicated for undamaged anterior teeth in dentitions with a
low caries experience. The presence of a small proximal carious lesion,
however, does not preclude its use.
If a high esthetic requirement exists, the advantage of this restoration is
that the labial tooth surface remains intact, although this is sometimes
offset by the display of a slight amount of metal along the incisal edge.
Pinledges can be prepared on bulbous teeth that are unsuitable for three-
quarter crowns, which would result in a significant amount of unsupported
enamel interproximally.
The lingual concavity of a maxillary anterior tooth can be modified
successfully with a pinledge restoration to establish the desired anterior
guidance.

55. Contraindicatio
nPatients with poor oral hygiene or a high caries rate are not good candidates
for this type of restoration. Young patients with large pulps generally are
better served by a resin-retained FPD.
Often it is not possible to place pinholes of adequate size and length in teeth
that are thin labiolingually.
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. Because less surface area is involved in the preparation,
pinledges are not as retentive as their less conservative counterparts.
Therefore they should not be used when optimum retention is needed.
Pinledge preparation on a maxillary central incisor

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

57. Design
Draw the outline of the proposed preparation onto the tooth. A line is
marked along the height of contour of the incisal edge and on the
proximal wall to include the area needed for a connector. The lingual
chamfer is placed immediately adjacent to the crest of the marginal
ridge. The cervical extent of the margin is on the height of contour of the
cingulum, but it may be extended farther cervically at a later stage to
blend into the proximal aspect of the preparation.
Malpositioned six caries free anterior teeth are for pinledge preparation

58. Proximal reduction
Prepare the proximal slice with a tapered diamond.
The diamond is either held parallel to the path of withdrawal or given a slight
lingual inclination. The primary purpose of this step is to provide sufficient
reduction to allow adequate metal in the area for a subsequent connector.
The proximal reduction includes the proximal contact area, but care must be
taken not to extend the reduction too far facially, because this will alter the
outline form of the tooth. For esthetic reasons, the reduction must not extend
onto the labial surface.

59. Incisal and lingual reduction
Prepare the incisal bevel with the diamond inclined slightly toward the
lingual. It extends just beyond the previously placed pencil line on the
crest of the incisal edge, but it must remain within the curvature of the
incisal edge to minimize display of metal. Sufficient clearance provides
functional contact on metal rather than on the junction between metal
and tooth structure. The desired metal thickness is 1 mm, except in the
area close to the margin.
Perform the lingual reduction with a foot-ball or wheel-shaped diamond
after placing reduction grooves as has been described in other anterior
preparations. Metal thickness of 1 mm is required in the intercuspal
position and throughout excursive movements.
The reduction follows the lingual marginal ridge and continues its
chamfer configuration cervically until it runs into the proximal reduction.
To facilitate subsequent stages of the preparation, care must be taken to
maintain as much tooth structure as possible in the incisal third.
Smooth the incisal and lingual reduction with fine-grit diamonds and
stones before preparing the ledges and pinholes

60. Ledges and indentations
Two ledges are prepared across the reduced lingual surface. They will
provide room for sufficient bulk of metal to ensure rigidity. The
restoration would otherwise not be very strong because it would consist
of only a thin sheet of metal.
The ledges are prepared parallel to the incisal edge of the tooth as
viewed from the lingual and parallel to one another as viewed from the
incisal. In selected areas they will be widened to provide indentations of
sufficient size to accommodate the pinholes. The determination of the
inciso-cervical location of the ledges depends on the configuration of the
pulp and the available bulk of tooth structure.
Location of the ledges relative to the height of the crown

61. Usually the incisal ledge is prepared 2 to 2.5 mm cervical to the incisal
edge, or one fourth of the total height of the preparation from the incisal
edge. The cervical ledge is placed on the crest of the cingulum at the
center of the cervical one fourth of the preparation.
Prepare two ledges with a cylindrical carbide bur. The recommended
minimum width for the ledge is 0.7 mm. Drawing the proposed location of
the ledges on the lingual surface of the tooth is helpful. The design of the
ledges must be compatible with the path of withdrawal of the restoration,
which is parallel to the incisal two thirds of the labial surface of the tooth.
Relationship between pinhole placement and pulp configuration
Maxillary Central incisor Maxillary Lateral incisor Maxillary canine

62. Cross section through cervical pinholes
Cross-section through incisal pinhole
Maxillary Central incisor Maxillary Lateral incisor Maxillary canine
Maxillary Central incisor Maxillary Lateral incisor Maxillary canine

63. Make indentations in the left and right sides of the incisal ledge and
slightly off center in the cervical ledge to prevent subsequent pulp
exposure when the pinholes are placed. These incisal indentations will be
as widely spaced as possible to retain as much dentin as possible
between the pinholes and the pulp.
Because the completed pinhole must be surrounded by sound dentin, it is
not possible to place holes in the extreme corners because of the tooth's
morphology. However, every effort should be made to prepare the
indentations so that the pinholes will be surrounded by dentin and away
from the pulp. This is particularly important for younger patients.
Generally this means that the indentations are just within the mesial and
distal marginal ridges, about 1.5 mm inside the external tooth contour. The
same carbide bur can be used to prepare the indentations.
When completed, the configuration of the indentations should resemble a
half cylinder. Again, their orientation is parallel to the selected path of
withdrawal and their floor should be smooth and continuous with the floor
of the ledges. When combined, they should provide a flat area 1 to 1.2
mm wide buccolingually.

64. Pinhole preparation
Sink pilot channels with either a small, round bur or a small twist drill. The
shallow indentations will prevent skating of the selected bur. The depth of
the completed pinhole should be at least 2 mm but can be as much as 3
mm when the placement and orientation of the pilot channels are
satisfactory.
Enlarge and deepen the pilot channels with a tapered carbide bur when
their placement and orientation are satisfactory. At this stage, any small
corrections in orientation can be made. Less experienced operators may
spend a great deal of time attempting to determine the correct alignment
of the bur.
However, it should be remembered that the design and location of the
pinholes have already been determined by the placement of the ledges
and indentations, so the only remaining concern should be verification of
the position of the rotary instrument and attainment of the minimum depth
of the pinholes.

65. Some operators find it helpful to place a second bur in a prepared pinhole
to help transfer the path of withdrawal, although precautions must be
taken to prevent its being swallowed or inhaled. Preparing multiple
pinholes a little at a time may also be helpful, moving from one to the
next and gradually deepening each. This will permit alignment verification
as the pinholes are
prepared.
Bevel the junction between pinhole and indentation with a round bur
slightly larger than the largest diameter of the pinhole.
Inspect all surfaces of the preparation for smoothness and evaluate the
margin. Correct any area that requires more distinct delineation.

66. REFERENCE

67. Contemporary Fixed
Prosthodontics
SECOND EDITION
Stephen F. Rosenstiel
Martin F. Land
Junhei Fujimoto

68. Contemporary Fixed
Prosthodontics
THIRD EDITION
Stephen F. Rosenstiel
Martin F. Land
Junhei Fujimoto

69. THANK YOU