2. Component :
1-Introduction :
2-Indications
3- objectives of tooth preparation
4-Factors to Consider Before and During
Tooth Preparation
5-Terminology
6-G.v Black’s classification
7-Stages of Tooth Preparation
3. Introduction :
Tooth preparation is the mechanical
alteration of a defective, injured, or
diseased tooth in order to best receive a
restorative material which will
reestablishes a health state for the
tooth including esthetic corrections,
where indicated along with normal
form (and therefore function)
4. - the basic principle
governing the
design of cavity and
steps in their
preparation was first
suggested by Dr. G.v
black in the first
decade of last
century
5. Indications :
( Restore the form and
function )
- Repair of tooth after destruction
due to caries or truma
- Repair the tooth with serious
defects such as poor esthetic
6. the objectives of tooth
:preparation
(1) conserve as much healthy
tooth structure as possible,
(2) remove all defects while
simultaneously providing
protection of the pulp–dentin
complex
7. (3) form the tooth preparation so that,
under the forces of mastication, the
tooth or the restoration (or both) will
not fracture and the restoration will
not be displaced,
(4) allow for the esthetic placement of a
restorative material where indicated
8. Factors to Consider Before and During
Tooth Preparation:
Patient Factors
Home care
Age
Cooperation
.Patient economic status
Patient concern for esthetic purpose
9. Anatomical Factors
. direction of enamel rods
• Dentin thickness
• Pulp location
• Coronal contours
• Extent of previous restoration
10. Procedural Factors
Operator skill
Instrument design
Ability to isolate
Other planned treatment should be
considered e.g using the tooth as
abutment in R.B. D of F.P.D
11. Factors to Consider Before and
During
- - - Lesion/Defect Factors
• Bone support
• Occlusion
• Gingival status
• Pulpal status
• Fracture development
13. Terminology
- enameloplasty : is the process
of conversion of shallow pit ,
groove ,or fissures into a
rounded or saucered self
cleansable aera
- depth of enameloplasty not
extend than 1/3 of enamel depth
14. -affected dentin : has no bacteria ,
reversibly denatured , remineralizable
and should preserved.
- infected dentin : has bacteria,
irreversibly denatured, not
remineralizable and should be removed
15. G.v Black’s classification
G.V. Black presented a classification
of tooth preparations
according to diseased anatomic
areas involved and by the
associated type of treatment
16. Class I preparations.:
All preparations required to treat pit-and-
fissure caries
include preparations on :
(1) occlusal surfaces of premolars and
molars,
(2) occlusal two thirds of the facial and
lingual surfaces of molars,
(3) the lingual surfaces of maxillary
incisors.
17. Class II preparations.
Preparations required to correct caries lesions
that develop in the proximal surfaces of
posterior teeth
Class III preparations
Preparations required to correct caries lesions
that develop in the proximal surfaces of anterior
teeth that do not include the incisal edge
18. Class IV preparations.
Preparations required to correct caries lesions or
other defects that develop in
the proximal surfaces of anterior teeth that include
the incisal edge
Class V preparations.
Preparations required to correct caries lesions or
other defects that develop in the gingival third of
the facial or lingual surfaces of all teeth
19. Class VI preparations
Preparations required to correct
caries lesions or other defects
that develop in the incisal edges
of anterior teeth or the occlusal
cusp tips of posterior teeth
20. Stage's of Tooth Preparation:
Initial Tooth Preparation Stage :
Step 1: Initial depth and outline form
Step 2: Primary resistance form
Step 3: Primary retention form
Step 4: Convenience form
21. Final Tooth Preparation Stage :
Step 5: Removal of defective restorative
material and/or soft dentin
Step 6: Pulp protection
Step 7: Secondary resistance and retention
forms
Step 8: External wall inishing
Step 9: Final procedures: debridement and
inspection
25. Definition: pleasing the cavity
margins in the position they will occupy
in the final preparation
- initial depth : 0.2 – 0.5 mm below D.E
junction
( 0.5 mm in direct gold restoration ) on
sound dentin
26. Principles
1. All week enamel should be removed
2. All faults should be included
3. Extenstion for prevention
(extending the preparation to self
cleansing areas and including the
pits and fissures to prevent
recurrence of caries)
27. Factors affect the outline form
1. Extent of the caries lesion , old
restoration
2. Esthetic consideration
3. Occlusal relationship (avoiding the
placement of cavity margins in area
of heavy occlusal contacts )
4. Cavosurface margin configuration
29. 8 Rules
1- Extention of cavity margin until
sound tooth structure obtained
2- Avoid terminating the margins on
extreme eminence e.g cusp
heights
3- Use enameloplasty ( when pit or
groove does not penetrate more
than 1/3 thickness of enamel
30. 4- If the distance between 2 faults or
cavity preparation is less than 0.5 mm
( connect it)
5- Depth of :
(0.2 – 0.5 mm ) for pit and fissure caries
( 0.2 – 0.8 mm ) for the axial wall of
smooth surface caries
Root-surface preparations may be
shallower than (0.8 mm ) if the restorative
material to be used does not require
secondary retention features.
31. 6- Extention the outline form to
provide sufficient access for
preparation and restoration
7-In proximal preparation
outline should be extend apical
to the proximal contact and
(1mm) apical to the crest of free
gingival
33. roles for cusp capping :
- out line form has extended no more
than 1/2 the distance from a primary
groove to cusp tip no cusp capping
-if the extension is from 1/2 – 2/3 distance
consider cusp capping
- if the extension is more than 2/3
distance cusp capping is mandatory
35. :
definition
defined as the shape and placement of
the preparation walls that best enable
the remaining tooth structure, as well
as the anticipated restoration, to
withstand masticatory forces primarily
oriented parallel to the long axis of the
tooth.
36. Principles:
1- Flat floors to prevent rocking
action of restoration
2-Removal of week enamel to
withstand the occlusal force
3-Rounding internal line angels to
reduce the stress on line angle
4-Week Cusp capping resistance to
fracture
37. 5- Placement of enough thickness of
restorative material
- the minimal occlusal thickness, for
appropriate resistance to fracture
Amalgam 1.5 – 2 mm
Porcelain 2 mm
Cast metal 1-2 mm
38. factors affect the Resistance
Form
(the need for develop resistance
form result of several factors )
1- Occlusal contact
2- Amount the remaining tooth
structure ( if the cavity is large
be conservative as possible as
you can)
3- Type of restorative material
39. features
a. relatively flat floor
b. box shape
c. inclusion of weakened tooth
structure
d. preservation of cusp and marginal
ridge
e. cusp reduction if needed
f. rounded internal line angles
g. adequate thickness of restorative
materials
43. - amalgam :
1. convergence of external cavity walls
occlusally (class I- class II )
-the mesial and distal walls should be
slightly diverged occlusally if
distance from the marginal ridge to
the proximal surface is less than 1.6
mm the prevent undermining of
marginal ridge
44. 2.diaverge of external cavity walls
occlusally (class III- class V )
provide strong enamel margins
3. occlusal dovetail
4. using adhesive system for
bounding amlgam to the tooth
structure
46. - cast metals :
1.parallel vertical walls to provide
retention of the casting in the tooth
2. small angle of divergence 2 -5 degree per
wall (retention is developed by
frictional resistance and mechanical
locking of the cement into the minute
irregularities of both casting and the
cavity wall )
47. - frictional retention depends
on 4 factors :
a. surface area of contact
between tooth and
restoration ( more
surface area increase
retention )
51. definition :
is the shape or form that
provides adequate
observation, accessibility,
and ease in the preparation
and restoration of the tooth.
52. Principles :
Modifications in tooth preparation includes
1- Flaring some walls more than
otherwise necessary e.g divergence of
vertical walls in class II
2- Extending proximal preparations
apical to the proximal contact
3-Separation by wedging of teeth makes
interproximal instrumentation
convenient
57. 1-negative esthetic result
2- compromise the retention
of new restoration
3- there is a radiographic
evidence of caries under the
old restoration
4- preoperative symptoms
60. --for effective pulp the
effective dentinal depth
(EDD) between pulp and
base of restoration should be
2mm . this may include the
remaining dentin liner or
base
62. Liner provide
Protects the dentin from noxious agents
from
1-restorative material or oral
fluids
2-Electric insulation
3-Thermal protection
63. Base provide :
Mechanical , thermal , electrical
protection , Example are :
zn phosphate
zn oxide eugenol
Ca (oH)2
polycarboxylate
GIC
64. Cavity varnish :
Solution liners which seals most of
the dentinal tubules and is placed
in all cavity preparation walls for
amalgam and cast gold
- prevent microleakage and
reduce postoperative sensitivity
66. Step 7 : Secondary
Retention and
Resistance Forms
67. the secondary retention and
resistance forms are of two
types :
(1) mechanical preparation
features
(2) treatments of the preparation
walls with etching, priming, and
adhesive materials.
68. Mechanical Features
1- Retention Grooves
proximal portions of some Class II
amalgam restorations
Coves.( Small retentive
indentions) incisal areas of Class
III amalgams.
70. 5- Skirts. Skirts are preparation features
used in cast gold restorations that
extend the preparation around some, if
not all, of the line angles of the tooth.
6- Beveled Enamel Margin
7- Amalgam Pin, Slot, and Pin : for
increased retention form for amalgam
72. definition :
-
development of a specific design e.g (
degree of smoothness or roughness, the
placement of a bevel)
immediately adjacent to or including the
cavosurface margin that produce
maximum effectiveness of the
restorative material being used
73. objectives
1- to create best marginal seal
between restorative material
and tooth
2-affort smooth marginal
junction
3-Provide maximum strength of
both material and tooth
margins
75. design of cavosurface angle:
Butt joint
90 degree cvosurface angle
amalgam
Silicate
Porcelain
Lap / slip joint
more than 90 degree cvosurface angle (140-150
degree)
cast and composite restoration
76. Step 9: Final Procedures:
Debridement and
Inspection
77. cleaning or debridement is
the act of freeing the
preparation walls and
margins from the objects
that may interfere with the
proper adaptation of
restoration
78. objectives :
a. freeing of all walls and floors
and margins from enamel and
dentin chips
b. drying of all walls and floors
from moisture , saliva , blood ,
exudates
c. sterilization of walls and floors
79. :
methods
a. water , air spray
b. cotton pellet
c. cavity cleansers ( low concentration
of citric acid+ ascorbic and acetic acid
( 1-10%) followed by long period of
water jet used only in shallow
cavities
d. scraping of walls , floors margins
with sharp instrument
80. Additional Concept in Tooth
Preparation
1 - for Amalgam
a- Tunnel Tooth Preparation for Amalgam
preparation joins an occlusal lesion by means
of prepared tunnel under the involved marginal
ridge, marginal ridge remains intact
b-bounded Amalgam Retoration
