2. CLASS I CAVITY
PREPARATION
GUIDED BY- DONE BY-
Dr. SANDEEP METGUD Dr. RAMSUNDAR HAZRA
Dr. DEEPALI AGRAWAL (1ST YEAR PG)
DEPARTMENT OF CONSERVATIVE DENTISTRY
AND ENDODONTICS
2
3. CONTENTS-
INTRODUCTION
DEFINITION
FACTORS TO CONSIDER BEFORE TOOTH PREPARATION
CLINICAL TECHNIQUE FOR CLASS I AMALGAM
a) CONSERVATIVE CLASS I
b) EXTENSIVE CLASS I
c) OCCLUSOLINGUAL CLASS I
d) OCCLUSOFACIAL CLASS I
CLASS I COMPOSITE RESTORATION
TOOTH PREPARATION:AMALGAM V/S COMPOSITE
REFERENCES 3
4. INTRODUCTION-
In the past, most restorative treatment was due to
Caries(decay).
A breach in the surface integrity was referred to as
Cavity.
Now many indications for treatment for teeth are
not due to caries, and the preparation of the tooth
no longer referred as Cavity preparation, but as
Tooth preparation.
4
5. Tooth preparation is the mechanical alteration of a
defective, injured, or diseased tooth to receive a
restorative material that re-establishes a healthy
state for the tooth, including esthetic corrections
where indicated and normal form and function.
(By Sturdevant)
Cavity preparation is the mechanical removal of
caries and shaping the remaining tooth tissue in
such a way so that after restoration it can withstand
masticatory forces and will be able to prevent
subsequent caries.
(By Vimal K Sikri)
5
6. CLASSIFICATIONS OF TOOTH
PREPARATION-
According to Anatomic areas involved and by
associated type of treatment was presented by
Black.
Designated as Class I, II, III, IV, V.
Class VI – additional Classification.
6
8. DEFINITION-
Class I Restoration-All pit and fissure
restorations are Class I, and they are assigned
to three groups.
A)Restorations on Occlusal Surface of
Premolars and Molars.
B)Restorations on Occlusal Two-Thirds of the
Facial and Lingual Surfaces of Molars.
C)Restorations on lingual Surface of Maxillary
Incisors. 8
10. Class I could be – a) Simple Occlusal Cavity
b) Compound Occlusal Cavity
-OcclusoBuccal
-Occluso Palatal/Lingual
c) Complex Occlusal Cavity
d) Buccal Pit
e) Anterior Palatal Pit
10
12. CLASS I LINE ANGLES AND POINT ANGLES
LINE ANGLES- fp:faciopulpal; df:distofacial; dp:distopulpal;
dl:distolingual; lp:linguopulpal; ml:mesiolingual: mp:mesiopulpal;
mf:mesiofacial.
POINT ANGLES- dfp:distofaciopulpal; dlp:distolinguopulpal;
mlp:mesiolinguopulpal; mfp:mesiofaciopulpal.
12
13. FACTORS TO CONSIDER BEFORE
TOOTH PREPARATION-
Extent of caries
Occlusion
Pulpal Involvement
Esthetics
Patient’s Age
Patient’s Home care
Gingival Status
Anesthesia
Bone support
Patient’s Desires
Material Limitations
Operator Skill
Enamel rod direction
13
14. FACTORS TO CONSIDER BEFORE
TOOTH PREPARATION-
Extent of old restorative material
Extent of defect
Pulpal protection
Contours
Economics
Patient’s Risk status
Bur design
Radiographic assessment
Patient cooperation
Fracture Lines
Tooth anatomy
Ability to isolate area
14
15. CLASS I AMALGAM RESTORATION-
Amalgam is used for the restoration of many
carious and fractured posterior teeth and in the
replacement of failed restoration.
If properly placed it provides many years of service.
Understanding the physical properties of amalgam
and the principles of tooth preparation.
15
16. TOOTH PREPARATION CLASS I
CONSERVATIVE CLASS I AMALGAM
RESTORATION
It is recommended to protect the pulp.
Preserve strength of the tooth.
To reduce deterioration of the amalgam
restoration.
TOOTH
PREPARATION
INITIAL TOOTH
PREPARATION
FINAL TOOTH
PREPARATION
16
17. CLINICAL TECHNIQUE OF CLASS I
AMALGAM-
INITIAL CLINICAL PROCEDURES
Isolation with Rubber dam-when removing deep caries
less than 1mm from the pulp.
For single Maxillary tooth, caries is not extensive,
moisture control is achieved with cotton rolls and
profound anesthesia.
Preoperative assessment of occlusal relationship of
involved and adjacent teeth.
17
18. INITIAL TOOTH PREPARATION
It is defined as establishing the outline form by
extension of the external walls to sound tooth structure,
while maintaining a specified, limited depth and
providing resistance and retention forms.
The Outline form for Class I should include only the
faulty, defective occlusal pits and fissures.
Occasionally the marginal outline for Maxillary
premolars is Butterfly shaped.
18
19. IDEAL OUTLINE FORM
Ideal outline form incorporates the following resistance form
principles-
Extending around the cusps to conserve tooth structure and
prevent the internal line angles from approaching the pulp
horns too closely.
Keeping the facial and lingual margin extensions as minimal
as possible between the central groove and the cusp tips.
Extending the outline to include fissures, placing the margins
on relatively smooth, sound structure.
Minimally extending into the marginal ridges without removing
dentinal support.
19
20. IDEAL OUTLINE FORM
Eliminating a weak wall of enamel by joining two
outlines that come close together i.e. <0.5mm
apart.
Extending the outline form to include enamel
undermined by caries.
Using enameloplasty on the terminal ends of
shallow fissures to conserve tooth structure.
Establishing an optimal, conservative depth of the
pulpal wall.
20
24. SEQUENCE OF PREPARATION
INITIAL TOOTH PREPARATION
Enter the deepest or most carious pit with a
punch cut using No. 245 carbide bur
As the bur enters the pit, the proper depth of
1.5mm should be established
Depth of external walls is 1.5 to 2mm;
Pulpal depth is 0.1 to 0.2mm into dentin 24
26. SEQUENCE OF PREPARATION
Incline bur distally to establish proper occlusal divergence
to distal wall
For Premolars, distance from the margin of extension to
the proximal surface should not be less than 1.6mm; For
Molars, the minimal distance is 2mm
While maintaining the bur’s orientation and depth, the
preparation is extended distofacially or distolingually 26
28. SEQUENCE OF PREPARATION
Maintain the bur’s orientation and depth and, with
intermittent pressure extend along the central fissure
towards the mesial pit, following DEJ
The pulpal floor should follow the DEJ,Maintain a uniform
flat pulpal floor depth
Ideally, the width of the isthmus should be just wider than
the diameter of the bur;
Minimal Faciolingual width and Minimal Occlusal
convergence are desired
28
29. SEQUENCE OF PREPARATION
Remainder of any occlusal enamel defects is included, facial
and lingual walls are extended if necessary
Conservative preparation should have an outline form with
gently flowing curves and distinct cavosurface margins
For Initial tooth preparation pulpal floor should remain at the
initilal ideal depth, even if restorative material or caries
remains,Remaining caries is removed in final tooth preparation29
31. PRIMARY RESISTANCE FORM
Sufficient area of relatively flat pulpal floor in sound
tooth structure.
Minimal extension of external walls.
Strong, ideal enamel margins.
Sufficient Depth(1.5mm)
PRIMARY RETENTION FORM
Parallelism or slight occlusal convergence of two or
more opposing, external walls.
31
32. FINAL TOOTH PREPARATION
Removal of remaining defective enamel and
infected dentin on the pulpal floor.
Pulp protection, where indicated.
Procedures for finishing external walls.
Final procedures of cleaning and inspecting the
prepared tooth.
32
33. SEQUENCE OF PREPARATION
FINAL TOOTH PREPARATION
Enamel pit and fissure remnants in the pulpal floor should
be removed
If pit and fissure remnants are few and small, they can be
removed with a suitably sized, round carbide bur or spoon
excavators
When removing infected dentin, the excavation should
be stopped when tooth structure feels hard or firm;A
sharp explorer is more reliable than a rotating bur in
judging the adequacy of removal of infected dentin
33
35. If the tooth preparation is of ideal or shallow
depth, no liner or base is indicated.
In deeper carious excavations-remaining
dentin thickness is 0.5-1mm-Place a thin
layer(0.5-0.75mm) of a light cured RMGI Base.
It should be placed only over the deepest
portion of the excavation.
The entire dentin surface should not be
covered.
Every completed tooth preparation should be
inspected and cleaned before restoration.
Tooth preparation should be free of debris after
rinsing tooth with air-water syringe. 35
37. An occlusal cavosurface bevel is contraindicated
in an amalgam cavity preparation.
Provide an approximate 90-100 degree
cavosurface angle which should result in 80-90
degree amalgam at the margins.
Amalgam is a brittle material with low edge strength
and tends to chip under occlusal stress.
37
39. OTHER CONSERVATIVE CLASS I
AMALGAM PREPARATIONS
Facial pit of Mandibular molar
Lingual pit of Maxillary lateral incisor
Occlusal pits of Mandibular 1st Premolar
Occlusal pits and fissures of Maxillary 1st Molar
Occlusal pits and fissures of Mandar 2nd Premolar
39
42. EXTENSIVE CLASS I AMALGAM
RESTORATIONS
Caries is considered extensive if the distance
between infected dentin and the pulp is judged to
be less than 1mm or when the facilolingual extent
of the defect is up the cuspal inclines.
Extensive caries requires a more extensive
restoration.
42
43. INITIAL CLINICAL PROCEDURES
Isolation of the operating site.
If caries excavation exposes the pulp,
pulp caping may be more often
successful if the site is isolated with a
properly applied rubber dam.
Preoperative occlusal assessment and
anesthetic administration-factors.
43
44. TOOTH PREPARATION-
INITIAL
Using a No. 245 bur at high speed and oriented with its
long axis parallel to the long axis of the tooth
crown,prepare the outline, primary resistance, and
primary retention form
An initial depth of 1.5-2mm should be maintained
The preparation is extended laterally to
remove all enamel undermined by caries by
alternatively cutting and examining the
lateral extension of the caries
44
45. TOOTH PREPARATION-
FINAL
Removal of remaining infected dentin
If pulp exposure occurs the operator must decide whether
to apply a direct pulp cap of calcium hydroxide or to treat
endodontically
For pulpal protection, a thin layer (0.5-0.75mm) of Calcium
hydroxide liner may be placed. 45
46. TOOTH PREPARATION-
FINAL
A thin base of RMGI should be used over Calcium hydroxide
Usually no Secondary resistance or retention features are
necessary
Primary resistance form-Extend the outline of the tooth
preparation to include only undermined and defective structure
Primary Retention-Occlusal convergence of enamel walls
46
47. CLASS I OCCLUSOLINGUAL AMALGAM
RESTORATIONS
Occlusolingual amalgam restorations may be used
on maxillary molars when a lingual fissure connects
with the distal oblique fissure and distal pit on the
occlusal surface.
Tooth preparation includes the following-
1) Tooth preparation should be no wider than
necessary.
2) Ideally mesiodistal width of the lingual extension
should not exceed 1mm except for extended caries
or undermined enamel.
3) When indicated, the tooth preparation should
be cut more at the expense of the oblique ridge
rather than centering over the fissure. 47
48. 4) Especially on smaller teeth, the occlusal portion may have a
slight distal tilt to conserve the dentin support of the distal
marginal ridge.
5) The margins should extend as little as possible onto the
oblique ridge, distolingual cusp, and distal marginal ridge.
48
50. CLASS I OCCLUSOFACIAL AMALGAM
RESTORATIONS-
Occasionally, mandibular molars
exhibit fisssures that extend from the
occlusal surface through the facial
cusp ridge and onto the facial surface.
50
52. CLASS I COMPOSITE RESTORATIONS
In 1959, Skinner wrote, ‘The esthetic quality of a
restoration may be as important to the mental
health of the patient as the biological and technical
qualities of the restoration are to his physical or
dental health.’
Composites are presently the most popular tooth-
colored materials, having completely replaced
silicate cement and acrylic resin.
The ADA indicated the appropriateness of
composites for use as pit and fissure sealants,
preventive resin restorations, and Class I and II
restorations for initial and moderately sized lesions.
52
53. ADA further stated, ‘ When used correctly in the
primary and permanent dentition, the expected lifetime
of resin-based composites can be comparable to that
of amalgam in Class I, Class II, and Class V
restorations’.
Composite is a material that has sufficient strength for
Class I and II restorations.
Because Composite is bonded to enamel and dentin,
tooth preparations for composite can be very
conservative.
53
54. CLINICAL INDICATIONS-
Small and moderate restorations
When esthetics is considered
Restorations that does not provide all of the
occlusal contacts
Restorations that does not have heavy
occlusal contacts
Restorations that can be appropriately
isolated
As foundations for crown
For economic/interim use reasons
54
55. CONTRAINDICATIONS-
When the operating site cannot be
isolated
Heavy occlusal stresses are
present
All the occlusal contacts are on
composite only
Restorations that extend onto the
root surface 55
58. CLINICAL TECHNIQUE FOR DIRECT
CLASS I COMPOSITE RESTORATION
INITIAL CLINICAL PROCEDURES-
Anesthesia and shade selection
Assessment of the preoperative
relationship of the tooth to be
restored
Isolation of the operating area 58
59. TOOTH PREPARATION
The three typical composite preparations-
Conventional, Beveled conventional and
Modified
Beveled Conventional design rarely would
be used except for groove extensions.
Conventional-When increased resistance
form is needed; for large preparations
Modified- Typically uses more flared
cavosurface forms without uniform or flat
pulpal or axial walls. 59
61. CONVENTIONAL CLASS I TOOTH
PREPRATION
For large Class I, one enters the tooth in the distal
pit area of the faulty occlusal surface with inverted
cone diamond, positioned parallel to the long axis
of the crown.
Pulpal floor-1.5mm initial depth
Facial and Lingual measurement-1.75mm depth
Initial depth- Approx. 0.2mm inside DEJ
Facial and lingual extension and width are dictated
by caries, old restorative material, or fault
Extensions into Marginal ridges should result in
approx. 1.6mm of thickness remaining tooth
structure for premolars and 2mm for molars 61
62. The occlusal margin does not have a beveled or
flared form, it is left as prepared
The inverted cone instrument results in occlusal
walls that converge oclusally, enhancing retention
form.
The marginal form of a groove extension on the
faical or lingual surface may be beveled with a
diamond, resulting in a 0.25-0.5mm width bevel at a
45 degree angle to the prepared wall.
A large Class I composite tooth preparation-
Conventional design.
If facial or lingual groove included- Combination of
Conventional and beveled conventional.
62
63. MODFIED CLASS I TOOTH PREPARATION-
Minimally involved Class I lesions or faults may be
restored with composite using modified tooth
preparations.
Less specific in form, having a scooped out
appearance.
Prepared with a small round or inverted cone
diamond or bur.
Initial pulp depth is still 1.5mm or approx 0.2mm
inside DEJ, but may not be uniform.
Entire bevel or flare becomes part of the final tooth
preparation.
63
64. CONCLUSION-
TOOTH PREPARATION: AMALGAM VS COMPOSITE
FEATURES AMALGAM COMPOSITE
OUTLINE FORM Include fault
May extend to break
proximal contact
Include adjacent
suspicious area
Same
Same
No
PULPAL DEPTH Uniform 1.5mm Remove fault; not
usually uniform
AXIAL DEPTH Uniform 0.2-0.5mm
inside DEJ
Remove fault; not
usually uniform
CAVOSURFACE MARGIN Create 90-degree
amalgam margin
> Equal to 90
degrees
64
65. FEATURES AMALGAM COMPOSITE
BEVELS None(Except Gingival) Large
preparation,
esthetics, and
seal
TEXTURE OF PREPARED
WALLS
Smoother Rough
CUTTING INSTRUMENT Burs Burs or
Diamonds
PRIMARY RETENTION
FORM
Convergence
Occlusally
None
SECONDARY RETENTION
FORM
Grooves, slots, locks,
pins
Bonding; grooves
for very large or
root surface
preparation
RESISTANCE FORM Flat floors, rounded
angles, box-shaped
Same for large
preparations
65
66. FEATURES AMALGAM COMPOSITE
BASE INDICATIONS Provide 2mm
between pulp and
amalgam
Not needed
LINER INDICATIONS Ca(OH)2 over direct
or indirect pulp caps
Same
SEALER GLUMA desensitizer
when not bonding
Sealed by bonding
system used
66
67. REFERENCES-
Sturdevant's Art and Science of
Operative Dentistry, 5th edition
2006.
Textbook Of Operative Dentistry,
By Vimal K Sikri
67