This document discusses the process of tooth preparation for restorations. It begins by defining tooth preparation and its objectives. It then covers factors to consider, terminology, classifications of cavity designs, and the stages of tooth preparation. The stages include initial preparation, primary resistance and retention forms, convenience form, and final procedures. Each stage is defined and discusses principles, features, and rules. The document provides a comprehensive overview of tooth preparation, outlining the key steps, considerations, and techniques involved to best prepare a tooth for restoration.

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

12. Restorative Material Factors
• Physical properties
• Color characteristics
• Cost effectiveness

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

22. Each step :
Definition
Principles
Factors affecting on this step
Features
Rules

23. Initial Tooth
Preparation Stages

24. Step 1: Initial Depth
and Outline Form

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

28. Features :

Preserving cuspal strength
Preserving marginal ridge strength
Minimum facio- lingual extention

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

32. 8- Consider the cusp
capping : 

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

34. Step 2: Primary
Resistance Form

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

40. Step 3 : Primary
Retention Form

41. Definition
is the shape or form of the
preparation that prevents
displacement or removal
of the restoration by
tipping or lifting forces

42. Principles
( depending on the material used )
1- amalgam
2- composite
3- cast metals

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

45. - composite:
Retention by
micromechanical boud
 so bevel enamel margins
increase the surface area to
be etched

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 )

48. b. opposing walls
(more opposing walls
more retention )

49. c.parallelism of walls
( parallel walls have higher
degree of retention )

50. Step 4:
Convenienc
Form

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

53. Final Stage of Tooth
Preparation

54. Step 5 : Removal of
Defective Restorative
Material
and/or Soft Dentin

55. Definition
is elimination of any infected
carious tooth structure or
faulty restoration left in the
tooth after initial cavity
preparation

56. Old restoration should
be removed
when ???

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

58. Step 6: Pulp
Protection

59. From what ????
Mechanical factors
Thermal factors
Chemical factors

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

61. Remaining dentin thickness
1- RDT ( 1.5 – 2 mm)
No base ,no liner , varnish
indicated
2- RDT (1 -1,5 mm)
ZOE liner except under composite
3- RDT (0.5 -1 mm)
Ca(OH)2 liner is indicated

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

65. Film thickness :
(1- 50 micron)
 2- 5 micron
(20 -25 ) micron
Thin liners
a- varnishes
b- suspention liners
0.2 – 1 mm
Thick liners
1- 2mm
bases

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.

69. 2-occlusal dovetail outline
3-proximal boxes
4-Preparation Extensions.

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

71. Step 8: External
Wall Finishing

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

74. features
1- design of cavo surface
angle
2-degree of smoothness
of the walls

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

81. 2-for Composite Resin
sandwich technique
 use of GIC liner
material

82. Thank you