The document discusses various factors to consider when planning and performing tooth crowning procedures. It covers evaluating tooth structure and integrity, risk factors, endodontic treatment status, periodontal health, occlusion, and margin placement. It emphasizes the importance of a ferrule effect to provide resistance and longevity when using posts. Short teeth require special consideration of their position, function, and potential for surgical or orthodontic treatment prior to restoration. Proper treatment planning based on a thorough examination is necessary for successful crowning outcomes.

1. Dr. Bahjat Abu Hamdan
Consultant Prosthodontist.

2. Functional disability of a Pt. is increased by
increasing the MT number.
 Tooth ability to withstand normal function is
decreased with the loss of tooth sound tissues.
Successfully saving a badly damaged tooth
requires a thoughtful combination of many
aspects of dental treatment.
In the questionable and strategic teeth, think how
to replace before extraction.
 A thorough background in the principles and
techniques of restorative dentistry are required.


3. 
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In the treatment planning and evaluation for
tooth crowning , which is the topic of the lecture,
as in any other treatment planning, there is one
principle that should be kept in mind: treatment
simplification.
The restorative dentist, or prosthodontist, is the
one who should manage the sequencing and
referral to other specialist. Because he is the one
who will finish the treatment.
Based on the collected data (x Ray, study models
and clinical Exam.) evaluation of each case could
be done properly.

4. 
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1. Overview of restoration requirements will be exposed.
2. Assessment of a tooth in question will be divided into
A. patient-level risk factors
B. Pulpal/endodontic status.
C. Periodontal/occlusal assessment.
D. Evaluation of the remaining tooth structures.
1. Build up of the crown.
2. The cervical metallic collar ( the ferrule).
3. Margin location.
4. Evaluation of short teeth.
5. Crown lengthening.

5. All the requirements for tooth crowning are
done for sound and vital teeth which :
 Have Sound bone and periodontal tissue.
 Normal anatomy of the crown .
 Have normal 3D position in the dental arch;
So that a compromised tooth needs to be
evaluated based on biologic ,mechanic ,
functional and aesthetic principles before being
ready for crowning.
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9. 
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1. Over Reduced / Under Reduced
2. Over Tapered / Under Tapered
3. Sharp Angles / Corners
4. Undefined Margin
5. Irregular Margin
6. Margin Position
7. Marred Adjacent Tooth
8. Contact Unbroken
9. Functional Cusp Bevel location

10. Behavioral risk factors
 Compromised or poor oral hygiene
 Cariogenic diet
 Low exposure to fluoride
 Parafunctional habits
 Ability and willingness to adhere to a longterm maintenance protocol
 Smoking
These facotors affect the prognosis of the case.
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11. 
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The loss of structural integrity associated with
the access preparation, rather than changes in
dentin, that lead to tooth fracture.
Prior to core build-up, an assessment should be
made of the pulpal status of the tooth in
question. If the pulp is exposed or there are
signs/symptoms of irreversible pulpitis,
endodontic treatment should be performed.
In the case of an ET tooth, the quality of the
treatment should be assessed clinically and by
the x ray.

12. •
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Existing ET treated teeth need to be assessed
carefully for the following:
Good apical seal and lesion free.
No sensitivity to pressure.
No exudate.
No fistula.
No apical sensitivity.
No active inflammation.

13. 
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Unacceptable ET should be retreated in spite of the
lack of any symptom, others believe that a free
symptom short RCT done 6 month ago is different
from that one done 6 years ago.
Posting procedures require the removal of the RCF
which will disturb the state of the delicate balance
between the poor ET and the body defense
mechanism causing flare up
Today, ET results are reproducible, and
predictable therefore the restoration procedures
can commence in 2-3 weeks following the
completion of the ET .

14. 

Periodontal and gingival tissues should be
sound and bleeding free. Evaluation should be
done after excavation of carious tooth tissues.
The gingival tissue represent the biologic
width which should never be violated by the
restoration.
Teeth considered questionable were those with
deep probing depths, furcation involvement,
bone loss, and mobility.

15. 
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It is beneficial to restore teeth to the physiologic
occlusal plane and that over-erupted and tilted
teeth can potentially prevent normal tooth contact
during function and therefore require treatment.
In partly edentulous patients, such teeth may
create a problem when restoring the opposing
arch.
The scope of potential treatment ranges from
enameloplasty or orthodontic treatment to
extraction of severely tilted or over-erupted teeth.

18. 
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Moderate cases may require a partial or a fullcoverage restoration.
However, some cases may require a combination
of endodontic treatment, crown-lengthening
surgery, and a restoration to achieve a functional
tooth that lies correctly within the occlusal plane.
In case of posterior mesially or lingually inclined
teeth, its better to adjust it by orthodontic
procedure otherwise it may need endo-treatment
or using a partial crown.
Redistribution of the spaces to have normal size of
the replaced teeth for esthetic reason is mandatory.

24. 
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Due to the round section of their roots, upper
central position can be corrected(to certain limits)
if its rotated, in labial or in lingual position (no
skeletal malocc)
In the young patients, with proximal caries, drift is
more significant. Crowning of these teeth may
affect the adjacent ones. However, 1/4 to 1/3 mm
touch does not cause any problem. (don’t perforate
the enamel).
Severe attrition caused by bruxism may affect little
or at all the vertical dimension, because the
eruption of the teeth compensates the loss of tooth
tissues. Eruption done with the alveolar bone.

30. 
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In a 20-year retrospective study analysis of
1638 ET posterior teeth restored with amalgam
without cusp coverage, fracture was a
significant problem. Maxillary bicuspids with
MOD restorations showed the lowest survival
rate overall.
After 3 years period, the failure of resinrestored and amalgam restored ET teeth was
similar.

31. 
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The clinical longevity of ET posterior teeth (molars
and bicuspids) is significantly improved with coronal
coverage.
The amount of remaining tooth structure was a
significant factor in tooth survival.
Aqualina et al found that ET teeth without crowns
failed at a 6 times greater rate than crowned teeth.
The presence of a crown was more important than
the type of foundation restoration, although it was
noted that teeth with posts have decreased
resistance to fracture.

33. 1.Build up of the crown
Routine use of crown on ET may not be necessary
if the marginal ridge are intact
Cuspal deflection increased with increasing
cavity size in mandibular molars, and it was
greatest after endodontic access.
 they concluded that cuspal coverage is
important so as to minimize the danger of
marginal leakage and cuspal fracture in ET
teeth.


35. 
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1.Build up of the crown
A compromised tooth needs to be evaluated up
to the amount of the lost tooth tissues and the
functional stresses to withstand.
If the remaining sound tissues are less than
50%, an additional means to retain the core is
needed using a post in the root canal.
However, preparation of a post space adds a
certain degree of risk to a restorative
procedure, that may be root perforation, also it
may increases the chance of root fracture.

36. a radiograph of fractured maxillary
second
premolar with a metallic
prefabricated post

37. Post space preparation involves risk.
An unnecessary post was placed in
this largely intact mandibular molar.
Perforation occurred resulting in
eventual loss of the tooth .
.

39. 
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1.Build up of the crown
For these reasons, posts should only be used
when other options are not available to retain a
core. The need for a post varies greatly between
the anterior and posterior teeth.
If an ET anterior tooth is to receive a crown, a
post often is indicated. However, at least, 1mm
of sound tissues after prep is necessary, build
up could be done by LCC and prefabricated
post if the tooth is thick enough , otherwise a
casting post and core is indicated to withstand
the occlusal forces.

40. 1.Build up of the crown
Unless the destruction of coronal tooth structure is
extensive(more than 50%) a post is not needed , the
pulp chamber and canals provide adequate
retention for a core buildup .
Molars resist primarily vertical forces. The post to be
placed in the largest, straightest canal.
1.
palatal canal in the Maxillary molars .
2.
distal canal in the Mandibular molars.
3.
Post should not extend more than 7mm into the
root apical to the orifice of the root canal.


42. 1.Build up of the crown
Premolars are usually bulkier than anterior teeth,
but often are single-rooted teeth with relatively
small pulp chambers.
 For these reasons, they require posts more
often than molars. Premolars are more likely
than molars to be subjected to lateral forces
during mastication. It is important to alleviate
the lateral stresses . So that the canine will take
over the lateral stresses.


43. 1.Build up of the crown
 molars have more tooth substance and a
larger pulp chamber to retain a core buildup.
 In general, parallel post are more retentive than
tapered post, and threaded posts are more
retentive than cemented ones.

The use GG drills and P-reamers should
precede the instrument use of any post drills
that come with the prefabricated post kit.

45. 1.Build up of the crown
IMPORTANT PRINCIPLES FOR POSTS
 Retention and Resistance
 Retention is influenced the post’s length,
diameter and taper, the luting cement used and
whether a post is active or passive.
 Parallel posts are more retentive than tapered
posts.
 Diameter is less important than the other factors
listed.
 Resistance refers to the ability of the post and
tooth to withstand lateral and rotational forces.

46. 1. Build up of the crown
Acceptable guidelines for determining the
post length include the following:
 the post length should be equal to the clinical
crown length.
 the post length should be equal to 1/2 to 2/3 of the
length of the remaining root.
 the post should extend to 1/2 length of
the root that is supported by bone.
It is accepted widely that the post diameter makes
little difference in the retention of the post.

47. No matter how the length of the post is but 4-5 mm
of gutta-percha is necessary to ensure an adequate
apical seal.
 Vertucci: FJ. Root Canal Anatomy of the human
teeth 1984. Lateral Root Canal Occur:
 73.5% in the apical third.
 11.4% in the middle third.
 6.2%
in the cervical third.
 A root always contains a root canal even though
when is not visible in the X ray and is difficult to
locate and negotiate.

49. Whaledent parallel 8 mm
Whaledent parallel 5 mm
Unitek tapered 8 mm
Unitek tapered 5 mm
0
5
10
15
20
25
30

52. 
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1. build up of the crown.
Resistance is influenced by the remaining tooth
structure, the post’s length and rigidity, the
presence of anti rotation features, and the presence
of a ferrule.
A restoration lacking resistance form is not likely
to be a long-term success, regardless of the
retentiveness of the post.
Minimal enlargement of the post space means the
post must be made of a strong material that can
withstand functional and parafunctional forces.
Post maximum diameter 1/3 of the root section.

56. This cast post and core had adequate
length for retention, but
failed because of the lack of resistance
form.

57. Post and crown loosened from
maxillary canine a few months
after placement. Both the
core/prefabricated post
and the crown came off (a).
Clinical photograph shows
the absence of cervical tooth
structure ( no ferrule) for
resistance
of the crown

58. 
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2.The Ferrule Effect
The “ferrule effect” is important to long-term
success when a post is used. A ferrule is defined as
a vertical band of tooth structure at the gingival
aspect of a crown preparation. It adds some
retention, but primarily provides resistance and
enhance longevity.
studies have shown maximum beneficial effects
from a ferrule with 1.5 to 2 mm or more of vertical
tooth structure. Crown lengthening and forced
eruption are used to expose the tooth sound tissue.

59. 
Crown ferrules increase the tooth’s resistance
to fracture.

62. 
Dissimilar metals and alloys have
different electric potentials. When two or more
come into contact with one another a galvanic
couple is created. One metal acts as an anode
and the other as a cathode. There is a potential
difference between the two dissimilar metals
which causes an accelerated attack on the
anode. The anode metal dissolves into the
electrolyte and deposition is formed on the
cathode metal.

63. 
Corrosion can be defined as the graded
degradation of materials by chemical or
electrochemical attack. This phenomenon is of
concern particularly when metallic implants,
metallic/silver fillings, or orthodontic
appliances are placed in the hostile electrolytic
environment provided by the human mouth.
Corrosion can severely limit the fatigue life and
ultimate strength of dental materials leading to
mechanical failure.

65. 
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2. Ferrule effect: wide posts in severely
compromised teeth with little or no residual
crown structure will fail for a variety of reasons
but typically by catastrophic root fracture.
Without adequate circumferential tooth
structure, occlusal forces are directed internally
down the root creating a wedge effect and the
high likelihood of root fracture. Also
incomplete ferrule which does not include the
tooth filling in the cervical area may result in
recurrent caries.

68. Crowned maxillary bicuspid with
extra wide, tapered
cast post and minimal ferrule
showing typical vertical
root fracture

71. 3.Margin location
Supragingival
equiginguval
Subgingival; presence of
caries or tooth fracture
Increase retention of preparation
Esthetic

72. 
BW. Violations can be corrected by either
surgically removing bone away from proximity
to the restoration margin, or orthodontically
extruding the tooth and thus moving the
margin away from the bone, or both.

73. 
Biological width:
 It is the sum of the supracrestal fibers, the
junctional epithelium, and the gingival
sulcus and has a proposed minimal
dimension of 3 mm

74. 3. Margin location.
Rules Can be used to place margins.
Sulcus probes 1.5mm or less : margin could be
placed 0.5 mm below the gingival tissue
Sulcus probes more than 1.5 mm, margin can be
placed in half the depth of the sulcus.
If the sulcus is greater than 2 mm gingivectomy
could be performed to lengthen the tooth and
create 1.5 sulcus. Then the pt. can be treated as
per the first rule.

81. 4. Evaluation of short teeth.
must be established. Restorative assessment should
include:
 1. Consideration of the arch position of the tooth.
 2. Strategic value of the tooth.
 3. Periodontal considerations.
 4. Crown-to-root ratio.
 5. Inter arch space occlusion.
 6. Endodontic treatment feasibility.
 7. Esthetics.
 8.Supraerupted opposed teeth.

82. 4. Evaluation of short teeth.
 The restoration of teeth with SCC has included the
following techniques:
 1. Alteration of tooth preparation design and
placement of auxillary retention and resistance form
features.
 2. Placement of foundation restorations.
 3. Surgical crown lengthening
 4. Orthodontic eruption.
 5. ET and overlay removable partial dentures.
 6.Pulp chamber crown, and adjustment of the opposed
tooth to the physiologic occlusal plane and lower
anterior teeth in deep overbite.

83. 
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5. crown lengthening
Crown-lengthening surgery is designed to increase
the clinical crown length. To preserve biologic
width. and prevent attachment loss, restorative
margins should be at least 3-4 mm from crestal
bone.
Sub gingival restorative margins should be
properly contoured an adequate band of
keratinized tissue is mandatory.
Consider the benefits of periodontal surgery and
orthodontic extrusion in improving the
restorability conditions of the damaged teeth with
strong roots in the alveolar bone.

84. 5.Indication of crown lengthening;
 Inadequate clinical crown for retention due to
extensive caries , sub gingival caries or tooth
fracture, root perforation, or root resorption within
the cervical 1/3rd of the root in teeth with adequate
periodontal attachment.
 Short clinical crown.
 Placement of sub gingival restorative margins.
 Unequal, excessive or unaesthetic gingival level for
esthetics.
 Violation of biologic width.

85. 5.Contraindication of crown lengthening.
 1. Teeth with deep carious lesions or fractures.
 2. With restorable teeth, crown lengthening is
contraindicated when there is an unfavorable crownroot .
 3. Exposure of furcation introduces potential
periodontal breakdown and puts prognosis of the tooth
in question.
 4. Crown lengthening on a single anterior tooth causes
uneven gingival contour, which is esthetically
unpleasing smile line .
 5. Patients with debilitating systemic diseases or poor
plaque control may compromise the healing potential
and are contraindicated for surgery.

86. THANKS FOR
YOUR
ATTENTION