2. History
Operative Dentistry was considered to be the entirety
of the clinical practice of dentistry, from which most
other aspects do dentistry evolved.
3. History
In USA, Dentistry originated in 17th century, when
several barbers were sent from England.
Dental practice was limited to tooth extraction without
scientific-basis.
4. History
In 1840, First evidence for dental education at
Baltimore college of dental surgery,
followed by starting dental programs in Harvard
University in 1867.
5. History
G. V. Black became the founder of the dental professions,
(Why?)
• Related the clinical practice of dentistry to a scientific
basis.
• Standardized both; cavity preparation & manufacturing
process of silver fillings.
The scientific foundation for operative dentistry was further
expanded by black's son, Arthur Black.
6. Definition:
It is the art & science concerned with all procedures by
which defects in hard structures are diagnosed,
treated, eliminated, prevented & the lost teeth
structures are restored.
7. Factors affecting operative treatment
I. Indications:
The three main categories that primary needs
restorative treatment:
1) caries
2) malformed, discolored , non-esthetic, or fractured
teeth
3) restoration replacement or repair.
8. Factors affecting operative treatment:
II. Considerations:
1. An understanding of and appreciation for infection
control measurments.
2. A thorough examination of not only the affected tooth.
3. A diagnosis of the dental problem.
4. A treatment plan to enhance the overall health and
well-being of the patient
9. Factors affecting operative treatment:
II. Considerations:
5. An understanding of the material to be used to restore the
affected area.
6. An understanding of the microbial nature of oral
environment
7. The necessary biologic knowledge of the various tooth
components and supporting tissues.
8. The effect of the operative procedure on other dental
treatments.
10. Factors affecting operative treatment:
III. Conservative Approach:
The rule “Extension
for Prevention” is not
followed any more,
(Why ?) Caries
Prevention
Methods
Improved
Restorative
Materials
Advanced
Clinical
Techniques
11. Factors affecting operative treatment:
III. Conservative Approach:
More conservative approaches are now available for:
1) Many typical restorative procedures (classes I, II, III, IV,
and V).
2) Diastema closure procedure.
3) Esthetic and/or functional correction of malformed,
discolored, or fractured teeth.
4) Actual replacement of teeth.
12. Factors affecting operative treatment:
IV: Dynamics Of Operative Dentistry:
Advances in treatment techniques, philosophies, and
materials almost certainly will be made, just as in the
past several decades, technological and scientific
advances have dramatically affected the need for
restorative services.
13. Projected Need For Operative Dentistry:
1) Restorations for teeth with carious lesions.
New caries:
• Caries incidence in children
(ages 5 to 17) is 45% .
• By age 17, 3:4 adolescents
have experienced caries.
• caries percent may be
higher in people over 55
years old .
Less than 6% of people
ages 18 to 64 have no caries.
Root caries:
increased of Root caries
incidence is due to:
• periodontal diseases.
• systemic problems
¼ of all dentate adults have
evidence of root caries.
14. Projected Need For Operative Dentistry:
2) restorations to replace existing, faulty restorations.
75% of all operative treatment is due to replacement of
existing restorations, specially for patients older than 40.
15. Projected Need For Operative Dentistry:
3) Restorations to enhance the esthetic appearance of
patients.
The incidence of Esthetic Restorations is increased due to:
• the publicity in the form of magazine articles, television
shows, and special news programs.
• With more teeth being retained, more people are likely to
seek appearance enhancement.
10% of a dentist's gross income was derived from esthetic
treatment on non-carious teeth.
16. Public's Perception Of Dentistry:
The public considers dentists and dentistry very positively.
• The public ranks a dentist as one of the most respected
members of the community.
• Dentistry has the highest satisfaction rating when the
public assesses the services they receive.
• The public appreciates the benefits of good dental
health.
All of this suggests a continuing demand for operative
services.
18. 2) Erosion:
Definition:
It is the irreversible loss of tooth structure due to
chemical dissolution by acids not of bacterial origin.
19. Causes:
Extrinsic acidic sources
• Acidic drinks and foods of low pH include; fruit
juices, sports drinks, and carbonated drinks.
Intrinsic acidic sources
• Gastric acid from the stomach comes into contact
with the teeth, associated with diseases such as
anorexia nervosa, bulimia, and gastroesophageal
reflux disease often suffer from this.
20. 3) Abrasion:
Definition:
It is the abnormal loss of the tooth structure due to
frictional forces from a foreign element
Causes:
Possible sources of this wearing of tooth are
toothbrushes, toothpicks, floss, and any dental
appliance frequently set in and removed from the
mouth.
21. • The appearance is commonly described as V-
shaped .
• The teeth most commonly affected are premolars
and canines.
22. 4) Attrition:
Definition:
• It is the mechanical wear of the incisal or occlusal
surfaces as a result of functional or para functional
habits (Bruxism, Clenching).
N.B:
It includes proximal surfaces at the contact area due to
the physiological tooth movement.
24. 5) Fracture
Classification:
I. Incomplete Fracture Not Involving The Pulp
(Cracks)
• Not painful, or pain is associated with
mastication.
• Patient can't identify the offended tooth.
• Difficult to be diagnosed or treated.
25. 5) Fracture
Classification:
II. Complete fracture
• Not involving the pulp
If Limited to enamel not sensitive.
If Limited to dentin sensitive (due to exposed
dentin / irritation of PDL).
• Involving the pulp
Sever pain, increases with infection
26. 6)Nonhereditary Enamel Hypoplasia:
Definition:
It is defective enamel formation with whitish to light
brown area due to the injury of ameloblasts during
enamel deposition,
Most common site:
• Anterior teeth, 1st molars
27. 7) Amelogenesis Imperfecta:
The enamel is defective either in form or
calcification as a result of heredity and has an
appearance ranging from essentially normal to
extremely unsightly
28. 8) Dentinognesis Imperfecta:
It is a hereditary condition in which only the
dentin is defective. Normal enamel is weakly
attached and lost early.
30. Introduction & Definitions
Dental plaque:
It is a gelatinous mass of bacteria adhering to the
tooth surface.
• The plaque bacteria metabolize refined
carbohydrates (sucrose) for energy and produce
organic acids as a by-product. These acids may
cause a carious lesion by dissolution of the tooth's
crystalline structure.
31. Introduction & Definitions
Dental caries:
• It is an infectious microbiologic disease of the
teeth that results in localized dissolution and
destruction of the calcified tissues.
32. Etiology of Caries
• Oral bacterial flora composed of a complex
community of many species, represented as a
mass of tightly packed cells held together by
the sticky matrix of polymerized glucose.
33. • The most common cariogenic bacteria is
Streptococcus mutans (MS) & lactobacilli that
produce great amounts of acids (acidogenic),
are tolerant of acidic environments (aciduric),
are vigorously stimulated by sucrose.
34. Etiology of Caries
• Exacerbations of caries activity are
characterized by periods of high bacterial
metabolic activity and low pH in the plaque
near the tooth surface.
• The pH rises (above 5.5) during intervening
episodes, aiding in remineralization of the
damaged tooth structure using calcium and
phosphate ions in Saliva.
35. Epidemiology of Caries
• The number of individuals in a population
having a disease at a specific point in time is
known as the prevalence of the disease.
The number of individuals developing new
cases of disease in a population over a specific
period of time, usually 1 year, is the incidence
of the disease.
36. Epidemiology of Caries
The most common epidemiologic measure of
caries is an evaluation of the number of
permanent teeth that are diseased, missing, or
filled DMF, (Measures of primary teeth are
reported as dmf).
based on teeth DMFT, dmft
based on surfaces affected DMFS, dmfs
37. Classification of Caries
1) according to the attack
• primary caries:
it is the first attack of caries in the previously
sound healthy tooth.
• Secondary (recurrent) caries:
it occurs with a restored tooth, at the borders of
a restoration then under it.
38. Classification of Caries
2) According to the onset
Acute (Rampant) Caries:
It is when caries rapidly damage the tooth structure
(painful, soft & light in color).
Chronic Caries
It Is When caries occurs over time and demands
regular dental intervention, (Brown in color).
Arrested Caries
It Is when caries progress paused without actual damage
to tooth structure, (Black in color).
39. Theories of Caries
1) Acidogenic Theory
2) Proteolytic Theory
3) Proteolysis Chelation Theory
40. Theories of Caries
1) Acidogenic Theory
caries is a chemo-parasitic process consisting of:
1st stage:
• fermentation of the food materials by micro-
organisms → liberation of lactic acids →
demineralization of the inorganic substance →
softening of the tooth.
2nd stage:
• dissolution of the soft part of the tooth, due to
the proteolytic enzymes of the micro-organisms.
41. Theories of Caries
2) Proteolytic theory
• It was found that caries can develop when the
pH of the dental plaque is 6-8
• It also can occur without the presence of of
food debris, as in:
Caries of impacted / uneruptrd tooth.
Caries under perfectly sealed restoration.
42. Theories of Caries
3) Proteolysis chelation theory
the release of a variety of complexing agents, as
aminoacids, poly phosphates and organic acids
which then dissolve the crystalline apatite.
43. Clinical Sites For Caries Initiation:
1. Developmental pits and fissures.
2. Smooth enamel surfaces.
3. Root surface.
44. The pits and fissures of newly erupted teeth are
rapidly colonized by bacteria.
Clinical Sites For Caries Initiation:
(1) Pits and Fissures:
45. There is considerable morphologic variation of
the pits and fissures that contributes to higher
susceptibility to caries.
a) shallow groove.
b) complete penetration.
c) end blindly.
d) open into an irregular
chamber.
Clinical Sites For Caries Initiation:
(1) Pits and Fissures:
46. Pit & fissure caries expands as it penetrates into
the enamel. Thus, the entry site may appear
much smaller than the actual lesion, making
clinical diagnosis difficult.
Clinical Sites For Caries Initiation:
(1) Pits and Fissures:
47. Common sites:
1. Proximal surfaces that are gingival to the
contact.
2. Non-contacting proximal surfaces because of
tooth surface contour or position.
3. Areas gingival to the height of contour of the
facial and lingual surfaces.
Clinical Sites For Caries Initiation:
(2) Smooth Enamel Surfaces:
48. Lesions starting on smooth enamel surfaces
have a broad area of origin and a conical, or
pointed, extension toward the DEJ. The path of
ingress of the lesion is roughly parallel to the
long axes of the enamel rods in the region
Clinical Sites For Caries Initiation:
(2) Smooth Enamel Surfaces:
49. • The root surface is rougher than enamel →
allowing plaque formation in the absence of
good oral hygiene.
• The cementum covering the root surface is
extremely thin and provides little resistance to
caries attack, and so progress more rapidly.
• Root caries lesions have less well defined
margins, tend to be U-shaped in cross-section.
Clinical Sites For Caries Initiation:
(3) Root Surfaces:
50. Histopathology of Caries
Enamel Caries
Histological Characteristics:
In cross-section, the gross appearance of a
carious lesion at:
• Pit & fissure lesion shows an inverted V with a
narrow entrance and a progressively wider
area of involvement closer to the DEJ.
• Smooth surface lesion shows a V shape with a
wide area of origin and the apex of the V
directed toward the DEJ.
51. Zones of Incipient Lesion:
1) The translucent zone.
2) The dark zone.
3) The body of the lesion.
4) The surface zone.
Histopathology of Caries
Enamel Caries
52. Zone 1: Translucent Zone
• The deepest zone is the translucent.
• It has a structureless translucent appearance,
• The pore volume of the translucent zone of
enamel caries is 1%, 10 times greater than
normal enamel.
Histopathology of Caries
Enamel Caries
53. Zone 2: Dark Zone,
• It does not transmit polarized light.
• It has a structureless dark appearance,.
• The total pore volume is 2% to 4%.
• The size of the dark zone is probably an
indication of the amount of remineralization that
has recently occurred.
Histopathology of Caries
Enamel Caries
54. Zone 3: Body of the Lesion,
• It represents the largest portion of the lesion
& has the largest pore volume, varying from
5% at the periphery to 25% at the center.
• The striae of Retzius are well marked,
indicating preferential mineral dissolution.
• Bacteria may be present in this zone if the
pore size is large enough to permit their
entry.
Histopathology of Caries
Enamel Caries
55. Zone 4: Surface Zone,
• It appears as unaffected enamel & has a lower
pore volume than the body of the lesion (less
than 5%)
• Layer radiopacity is comparable to unaffected
adjacent enamel.
Histopathology of Caries
Enamel Caries
56. Zones of Dentinal Caries
• Zone 1: Normal Dentin
• Zone 2: Subtransparent Dentin
• Zone 3: Transparent Dentin
• Zone 4: Turbid Dentin
• Zone 5: Infected Dentin
Histopathology of Caries
Dentin Caries
57. • In managing caries, the objective is to focus
on the diagnosis, preventive measures, and
treatment modalities.
• It is imperative to understand that restorative
treatment does not cure the carious process.
Instead, identifying and eliminating the
causative factors.
Management of Caries
59. Caries Diagnosis
The primary objectives of caries diagnosis are to identify:
Lesions require surgical (restorative) treatment.
Lesions require nonsurgical treatment.
Preventive strategies for persons who are at high risk
for developing carious lesions.
61. • Factors include: age (children and elderly),
gender, decreased fluoride exposure,
increased smoking habits, increased alcohol
intake, medications, high sucrose intake,
lower economic, lower educational status, and
poor general health result in increased risks
for caries development.
past caries experience is the best predictor of
future caries activity.
Caries Diagnosis
Assessment Tools
1) Patient history
62. • General information regarding inadequate
salivary functioning, plaque accumulation,
inflammation of soft tissues, poor oral
hygiene, and also are instructive in
determining potential risk to caries
development.
• The tooth surface is examined visually
and tactilely.
Caries Diagnosis
Assessment Tools
2) Clinical Examination
63. • Visual evidence of caries includes detection
of cavitation, surface roughness, faulty
existing restorations, opacification, and
discoloration.
Caries Diagnosis
Assessment Tools
2) Clinical Examination
64. • Drill & fill Approach means penetration and
resistance to removal of an explorer tip (a
"catch") have been interpreted as evidence of
demineralization and weakening of tooth
structure.
Caries Diagnosis
Assessment Tools
2) Clinical Examination
65. • Frequent exposure to sucrose increases the
likelihood of plaque development by the more
cariogenic MS organisms
Caries Diagnosis
Assessment Tools
3) Nutritional Analyses
66. • It may provide important information about
secretion rates, buffering capacity, and
numbers of both MS and lactobacilli.
Caries Diagnosis
Assessment Tools
4) Salivary Analyses
67. • Dental radiographs may show caries that is
not visible clinically.
• Despite of this, many proximal lesions evident
radiographically are not cavitated (60%) and
should be remineralized rather than restored.
Caries Diagnosis
Assessment Tools
5) Radiographic Assessment.
68. New techniques are available for earlier
detection, including digital radiography, and
quantitative light-induced fluorescence
69. • Discoloration of pits and grooves, limited to
the depth of the fissure or pit, is almost a
universal finding in normal healthy teeth of
adults.
Caries Diagnosis
For Pits And Fissures:
70. Cavitation at the base of a pit or fissure sometimes
can be detected tactilely or visually.
71. additional criteria have been developed by the U.S.
Public Health Service for pit-and-fissure caries
diagnosis. These factors are:
1. Softening at the base of the pit or fissure.
2. Opacity surrounding the pit or fissure.
3. Softened enamel may be flaked away by extensive
explorer penetration.
4. On bitewing radiographs, evidence of dentinal
caries.
Caries Diagnosis
For Pits And Fissures:
72. • Bitewing radiographs are the most typical
method for evaluation of the proximal smooth
surfaces.
• A common diagnostic error; noncavitated
caries appear as well-defined radiolucent
area,
Caries Diagnosis
For Smooth Surfaces:
74. • Root caries may become more common in the
population.
• Visual examination: shallow initially, spreads
laterally, discoloration associated with
remineralization.
• No patient symptoms.
Caries Diagnosis
For Root Surfaces:
• The lesion development
may be rapid
75. The goal is Limitation of tooth demineralization
by cariogenic bacteria, in order to:
• Control the already existed carious lesion .
• Prevent the initiation of new lesions.
Through:
(1) Limiting pathogen growth and metabolism.
(2) Increasing the resistance of the tooth surface
to demineralization.
Caries Prevention:
76. • A caries prevention program is a complex
process involving multiple interrelated factors,
such as:
1) General health
2) Fluoride exposure
3) Immunization
4) Salivary functioning
5) Antimicrobial agents
Which factor the patient usually is capable to
control?
Caries Prevention:
6) Diet
7) Oral hygiene
8) Xylitol gums
9) Pit & fissure sealants
10)Restorations
77. Declining health signals the need for increased
preventive measures, (Why?)
• Patients undergoing radio/chemotherapy have
significantly decreased immune-competence
and are at risk for increased caries.
Caries Prevention
1) General Health:
78. Fluoride in trace amounts increases the
resistance of tooth structure to demineralization.
Sources of fluoride: fluoridated community
water systems, diet, toothpastes, mouth rinses,
& professional topical applications.
• Excessive fluoride exposure (10 ppm or more)
results in fluorosis, a brownish discoloration of
enamel, termed mottled enamel.
Caries Prevention
2) Fluoride Exposure
79. Bacteria passing through the mouth into the
stomach and intestines → come into contact
with specialized lymphoid tissue (Peyer's
patches) → sensitizing certain T and B cells →
migrate through bloodstream → settle in the
salivary glands → produce IgA → secreted in
the saliva → agglutination of oral bacteria →
prevents adherence to the teeth.
Caries Prevention
3) Immunization
80. Xerostomia may occur because of aging, or
medication.
Consultation with the physician may be
necessary to identify alternate treatments, if
possible, with less salivary impact.
Saliva stimulants (gums paraffin waxes, or saliva
substitutes) .
also may be prescribed for patients with
impaired salivary functioning.
Caries Prevention
4) Salivary Functioning
81. Chlorhexidine
• It interacts with MS organisms while adhering
to oral structures.
• It was first available in the United States as a
rinse.
• Prescription: as a 0.12% rinse or varnish for
high-risk patients for short-term use.
Caries Prevention
5) Antimicrobial Agents
82. Caries activity is most strongly stimulated by the
frequency rather than the quantity of sucrose
ingested.
Caries Prevention
6) Diet
83. Daily removal of plaque by dental flossing, tooth
brushing, and rinsing is the single best measure
for preventing both caries and periodontal
disease.
Caries Prevention
7) Oral Hygiene
84. • Supragingival plaque → etiologic agent of
long-standing gingivitis → damage of the
epithelial attachment → progression to a
more serious periodontal disease.
• Oral hygiene measures → Effective plaque
control → resolution of the gingival
inflammation and remineralization of the
enamel surface.
Caries Prevention
7) Oral Hygiene
85. Indications:
• Prevent caries in newly erupted teeth,
• Arrest incipient caries, by cutting off the
nutrient supply to the pathogenic plaque
trapped under the sealant.
• Prevent odontopathogenic bacterial growth in
sealed fissures,
• Prevent infection of other sites.
Caries Prevention
9) Pit & Fissure Sealants:
86. The treatment regimen is dictated by the
patient's caries status.
• Patient with high risk for caries development,
treatment should consist of both restorative
procedures and many of the preventive
measures described previously.
Caries Treatment
87. Patients with acute carious lesions, caries
control restorative treatment may be indicated
first.
Technique:
(1) removing the infected tooth structure.
(2) medicating the pulp, if necessary.
(3) restoring the defects with temporary /
permanent.
(4) application of other preventive measures.
Caries Treatment
89. introduction
Rotary instruments are the most universally used
instruments for gross removal of tooth structure.
Rotary instruments are tools or attachment that are
fitted in the handpiece and work by energy delivered
from a source of power.
Handpiece
Rotary instrument
90. introduction
They are chiefly used for the removal of tooth
structure and restorative materials.
The ideal preparation is done by a combination of
rotary and hand cutting instruments.
91. Rotating instruments in operative dentistry are either:
1- Dental handpieces
2- Dental burs
3- Dental abrading tools
Each one is designed for a specific range of functions
92. 1- dental handpieces
a) straight handpieces.
b) Contra-angle handpieces:
i. Low speed contra-angle
ii. high speed contra-angle
93. a) straight handpieces
The long axis of the bur is the same of the long axis of
the handpiece.
It is mainly used in laboratory work .
94. b- contra-angle handpieces
i- low speed contra-angle
Its speed range is (500-35000 rpm).
It is used for :
Removal of deep carious dentine
Finishing and polishing procedures
95. Speed ranges in dentistry
low or slow speeds: <12000 r.p.m
medium or intermediate speeds:12000-200000r.p.m
high or ultra high speeds : >200000
96. b- contra-angle handpieces
ii – high speed contra-angle
Its speed range is (160,000-500,000 rpm).
It is used for :
It is very efficient in cutting both enamel and
dentin.
We should use coolant to avoid heat
generation from high speed.
97. Handpieces will retain the cutting tools by:
a. screwing
b. latch
c. friction grip
Types of Attachment:
98. 2- dental burs
The rotary tools used in removing tooth structures
may be classified into burs and abrasives depending on
whether they work by an actual cutting or an abrading
process.
The bur is considered a form of drills or milling
cutters specially manufactured to suit dental purposes.
99. Parts of dental burs
1. shank
It is the part that fit into the handpiece . It has
different lengths and shapes:
• Long straight shank for straight handpieces.
• Latch and tapered short burs for regular and
medium –speed handpieces.
• Friction-grip bur (contra –angle bur)for ultra
speed air turbine.
100. Parts of dental burs
2. neck
It connects the head of the bur to the shank.
the straight bur has longer neck .
The contra –angle bur has a shorter neck to permit its
use in posterior area.
101. Parts of dental burs
3. head
It is the working part of the bur.
according to the shape of the head rotary instruments
are classified into :
1) bladed cutting instruments(burs).
2) abrasive instruments(stones).
102. Types and classifications of burs
They may be classified according to their :
composition.
Shape of the shank.
Length of the neck.
Shape of the head.
103. Classification of burs according to their composition
Two kinds of burs are available that differ in hardness and
composition:
steel burs: they were the early materials of burs but they
became dull rapidly wich cause increased heat and
vibrations.so they are now used for finishing procedures.
carbide bur: they are harder , stiffer and stronger than
steel burs , but they are more brittle. They are used at
different speed ranges.
104. Classification of burs according to the shape of the
shank
(A): long straight shank: for straight handpiece.
(B): latch and tapered short burs: for regular and
medium – speed handpiece .
(C): friction-grip bur(contra – angle bur): for ultra-speed
air turbine.
105.
106. Classification of burs according to the length of
the neck
(A): short neck : in contra angle burs.
(B): long neck: in straight burs.
107. Classification of burs according to the shape of
the head
(A): Round or rose head burs
This shape is used for:
1) Initial entry into the tooth.
2) Extension of the preparation.
3) Caries removal.
4) Preparation of retentive features into the cavity.
108. Classification of burs according to the shape of
the head
(B): inverted cone burs
This design is used for:
1) Extension of the preparation.
2) Producing undercuts in the preparation.
3) Adding retentive features in the cavity.
109. Classification of burs according to the shape of
the head
(C): Regular plane fissure bur
It is elongated and cylindrical in shape, it is used for:
1) Extension of the cavity.
2) Preparation of the resistance and retention form.
110. Classification of burs according to the shape of
the head
(D): tapered fissure burs
it is used for:
1) Preparing inclination walls for cast gold restoration.
2) Preparing undercut grooves for retention of proximal
amalgam restorations .
111. Classification of burs according to the shape of
the head
(E): finishing burs
1) They have great number of blades (more than 8
blades, usually 12 blades).
2) They are used with low-speed for finishing and
polishing metallic restorations.
112.
113. Cutting efficiency of dental burs
Definition:
It is the ability of a bur to remove a maximum amount of
tooth tissues with a minimum of effort and time involved
114. Factors affecting the cutting efficiency
1) Bur design.
2) Technique and manner of use.
3) Bur composition.
4) Rotational speed.
5) The tissue to be cut.
115. Factors affecting the cutting efficiency
1) Bur design.
I. Number of blades
The more the number of blades, the greater the cutting
efficiency. However, this is within limits, the best
number of blades is (6-8) beyond which:
Weakening of blades occur.
Increased clogging tendency.
Increased heat generation.
116.
117. Factors affecting the cutting efficiency
1) Bur design.
II. Surface area of the blade:
the lesser the surface area, the greater the cutting efficiency
(e.g. since the surface area of a fissure bur is about 3 times
that of a corresponding size inverted cone, the latter is to be
15 times more efficient).
118. Factors affecting the cutting efficiency
2) Bur design
The operating pressure should be kept to a minimum by
exerting minimum load of force on the bur as more
pressure on the bur leads to:
Increases heat generation.
Increases dulling tendency of the bur.
Decreasing the cutting efficiency of the bur.
119. N.B.
Based on this, it can be concluded that the round bur is the
most efficient end-cutting bur. While, the inverted cone
and fissure burs are effective as lateral cutting tools and
must never be used for end cutting.
120. Factors affecting the cutting efficiency
3) Bur composition
Carbide burs are much more efficient than steel burs for
reasons of greater hardness, strength and better
manufacturing treatment and design.
Carbide burs cut enamel and dentine and their cutting
efficiency increases with increasing the rotational speed of
the bur.
While steel burs cut only dentine at low speed ranges.
121. Factors affecting the cutting efficiency
4) Rotational speed :
Cutting efficiency increases with increasing the rotational
speed.
5) Tissue to be cut:
Enamel is harder than dentine and cementum, so cutting in
enamel makes the bur less efficient than cutting in dentine
and cementum
122. 3- dental abrading tools
Types of abrading tools
There are different types of abrading tools varying
according to the abrasive material and form of the
head.
123. 3- dental abrading tools
Types of abrading tools:
A- diamond abrasives:
They are the hardest and most efficient abrasives
stones for removing tooth enamel.
The head may be in the form of cylinders, wheels,
tapering point or disks.
They are more efficient with medium speed ranges.
124.
125. 3- dental abrading tools
Types of abrading tools:
B- Sand paper and carborundum discs
They are useful in smoothening tooth structures and
metallic restorations.
126. 3- dental abrading tools
Types of abrading tools:
C- Rubber wheels:
They are used for metal polishing. Softer types are
preferred as they bend into the contours of the
restoration.
127. How to control heat generation by rotary tools?
1) Correct use of sharp tools of proper size as dull large
tools increase heat generation.
2) Avoid application of pressure on the rotary tools
while operating.
3) Selection of proper speed.
4) Use of coolant.
129. Hand instruments
General classification of instruments
Cutting hand instruments
excavators, chisels
Non-cutting hand instruments
amalgam condensers, mirrors, explorers, probes
A) Diagnostic instruments
B) Restoring instruments
130. Instruments that are used by the hands.
Parts of the hand instruments
Composed of 3 parts:Handle , shank , and blade(nib).
Noncutting instruments:the part corresponding to blade
is termed Nib
Blade on both ends of the handle are known double-
ended instruments
I. Hand instruments
132. The handle is used to hold the instrument.
Different sizes and shapes .
It may be smooth or serrated.
The number , series , manfacturer’s name are written
on the handle.
Handle(shaft)
133.
134. It connects handle with the working pointnib , blade
of the instrument.
It tapers from the shaft down to the blade and is
normally smooth , round or taperd
It may be straight or bent for better control of the
working point when force is applied.
The working point should be within 3mm to the center
of the long axis of the handle.
shank
135. According to the numbers of angles , the instruments are
classified as:
- Straight :no angle
- Mon-angle: one angle
- Bin-angle: two angles
- Triple-angle: three angles
If the shank has more than one angle ,it is termed (contra-
angled).
136. it is connected to the handle by the shank.
For cutting instrument, the working point is called blade.
For non cutting instrument, the working point is called nib.
If the blade is only in one end it is called single ended instrument.
If the blade is only in two ends it is called double ended instrument.
Working point :Blade(nib)
137. Most blades have three bevels :
- one on the end of the blade forming the primary cutting edge.
- two along the side of the blade forming the secondary cutting
edge .
- the instrument is called bi-beveled instrument .
Working point :Blade(nib)
138. 1- function (scaler , excavator).
2- manner of use (hand condenser).
3- design of the working end (spoon excavator , sickle scaler).
4- shape of the shank (mon-angle,bin-angle).
5- these names were combined to form the complete description
of the instrument:bin-angle spoon excavator
Black’s classification system by instrument
name categorized instruments by
139. Dr. G. V. Black classified instruments according to order
names, suborder names, class names, and subclass names.
Order names :denote the purpose for which the instrument
is to be used, such as mallet or clamps.
Suborder names :define the manner or position of use of the
instrument, such as hand mallet or molar clamps.
Class names: describe the working point of the instrument,
such as spoon excavator or inverted cone bur.
Subclass names: indicate the angle of the shank, such as bin-
angle.
140. Black’s instrument formula
Black’s formula describes :
the dimensions of an instrument.
the angulation of the instrument.
141. Hand - cutting instruments
(cut hard or soft tissues)
A- Excavators
Hatchet,hoes,spoons,
angle former
B- Chisels
Straight ,curved, bin –angle,
enamel hatchet
C- Others
Knives,files,carvers,gingival
marginal trimmer
142. Ordinary hatchet excavator:
The cutting edge of the blade directed in the same
plane of the long axis of the handle and is bi-beveled.
we use it primarily on anterior teeth to prepare
retantative areas and sharpening internal line angles
A- Excavators
143. Hoe excavators:
has the primary cutting edge of the blade perpendicular
to the axis of the handle.
we use it for: planning tooth preparation walls and
forming line angles.
used in class III and V for direct golden restorations.and
intended for use on enamel of posterior teeth.
A- Excavators
144. angle former:
• it is used for sharpening line angles and creating retentive
feauters in dentin in preparation for gold restorations .
• It also may be used in placing a bevel on enamel margins.
• It is mon-angled and has the primary cutting edge at an angle
(other than 90 degrees) to the blade.
• It may be described as a combination of a chisel and gingival
margin trimmer.
• It is available in pairs (right and left).
A- Excavators
145. Spoon excavators:
they are used for removing caries and carving amalgam or
direct wax patterns.
The blades are slightly curved and the cutting edges are either
circular or clawlike.
The circular edge is known as a discoid, whereas the clawlike
blade is termed a cleoid.
The shanks may be bin-angled or triple-angled to facilitate
accessibility.
A- Excavators
146. Straight Chisel:
The straight chisel has a straight shank and blade, with the
bevel on only one side.
Its primary edge is perpendicular to the axis of the handle.
B- Chisels
147. The bin-angle and Wedelstaedt chisels:
the primary cutting edges is in a plane perpendicular to the
axis of the handle.
may have either a distal bevel or a mesial (reverse) bevel.
The blade with a distal bevel is designed to plane a wall that
faces the blade's inside surface.
B- Chisels
148. Enamel hatchet:
it is similar in design to the ordinary hatchet except that the
blade is larger, heavier, and is beveled on only one side.
It has its cutting edges in a plane that is parallel with the axis of
the handle. It is used for cutting enamel and comes as right or left
types for use on opposite sides of the preparation.
B- Chisels
149. Gingival margin trimmer:
is designed to produce a proper bevel on gingival enamel margins
of proximoocclusal preparations.
It is similar in design to the enamel hatchet, except the blade is
curved.
the primary cutting edge is at an angle (other than perpendicular)
to the axis of the blade.
It is made as right and left types
B- Chisels
150. Other hand cutting instruments, such as the knife, file, and
discoid-cleoid instrument, are used for :
trimming restorative material rather than for cutting tooth
structure.
C- Other cutting instruments
151. 1- knives: known as finishing knives, amalgam knives,or gold
knives, are designed with a thin, knifelike blade that is made in
various sizes and shapes.
Knives are used for trimming excess restorative
material on the gingival, facial, or lingual margins of a
proximal restoration or trimming and contouring the
surface of a Class V restoration.
C- Other cutting instruments
152. File:
They used to:
trim excess restorative material.
They are particularly useful at gingival margins.
Blades of files are very thin, and teeth on the cutting
surfaces are short.
C- Other cutting instruments
154. A-Diagnostic instruments
These instruments are used in:
the assessment of tooth lesions .
differentiation between normal and affected tooth structure.
It can be helpful in the determination of the periodontal
condition of the tooth.
These instruments include:
Mirrors
Probes
explorers
155. Diagnostic instruments
Mirrors :
• Dental mirror is a tool specially designed for the purpose of
clear and distinct vision.
• It is available in a variety of sizes with flat or convex
magnifying surfaces.
They are used for :
To reflect light
Retract soft tissues
Indirect vision
Tissue protection
157. Diagnostic instruments
Probes:
They are similar to explorers but with blunt tip.
It is usually graduated to evaluate the periodontal
condition of the tooth .
160. B- restoring instrument
They are similar in appearance to cutting instruments
but their working end is a nib (non cutting).
They are divided into :
1) Amalgam application instruments (for amalgam).
2) Plastic instruments (for composite and glass
ionomer).
3) Others:
• Spatulas.
• Cavity liners applicators.
161. 1-Amalgam application instruments
Amalgam carriers:
Amalgam restoration is placed into the preparation with
an instrument with a hollow cylinder that is filled with
amalgam.
A plunger operated with finger pushes the amalgam out
of the carrier into the preparation.
163. 1-Amalgam application instruments
Amalgam condenser :
They are used to compress amalgam and push resin
composite or glass ionomer material into prepared
tooth .
The working end is usually round in section,with flat
smooth or serrated end.
It is supplied with different sizes and shapes of the nib
164. 1-Amalgam application instruments
Carvers:
They are used to: shape amalgam, resin composite and
tooth colored restorative materials .
They are also used to: remove excess amalgam as discoid
and cleoid carvers wich are used mainly for the occlusal
surface.
They have different nib shapes.
170. 1-Amalgam application instruments
Matrices
instruments wich give form to any thing .
it acts as a temporary wall in class II or III to enable the
condensation of the restorative material until it hardens .
it prevents the marginal overhangs and keeps the
gingival tissues away from the cavity during the whole
procedure.
172. 1-Amalgam application instruments
Types of the matrices
Ivory matrix holder no.8:
It can encircle the entire crown of the tooth and can be
used in all compound cavities particularly those with
three surfaces (MOD cavities).
173. 1-Amalgam application instruments
Types of the matrices
universal or tofflemire matrix band retainer:
It is the best one in its stability , anatomic adaptation
and easy construction and removal.
174. Tofflemire ( Universal ) Retainer
Head
Slots Retaining
screw
Adjustable
nut
Locking nut
Vise
Straight and contra-angled retainersOCCLUSAL
175.
176. 2- plastic instruments
They are called plastic because they were originally
used with plastic restorative materials.
They are used for: carving and shaping of composite
and glass ionomer restorative materials.
They are supplied with different shapes and sizes .
They are made either from plastic or metals.
178. 3- Others
Spatulas
Many restorative materials in the operative dentistry need
mixing , either on glass slab or paper pad so we use spatula
in this step.
It is supplied with different sizes and thickness :
- smaller spatula are used for mixing small amounts of
materials .
- thinner spatulas are mor flexible while thicker
spatulas are more rigid .
- the choice between them depends on the desired
vicosity of the restorative material.
179. 3- Others
Cavity liners applicator
it is a small instrument wich helps in applying cavity
liners in thin layers in the cavity.
It is very small ball in diameter.
180. Sharpening of the hand instrument
Instruments with dull cutting edges cause more pain,
prolong operating time, are more difficult to control,
and reduce quality and precision in tooth preparation.
Many types of sharpening equipment exist, including
stationary sharpening stones, mechanical sharpeners,
and stones that are used in the handpiece.
To make proper manual sharpening , the cutting part
should be placed facing the stone and instrument should
pushed and pulled 2-3 times with apropriate force
181. Importance of sharpening
Increase the cutting efficiency of the instrument.
Produce smoother surface for the cavity .
Reduce pain coming from heavy force on a dull
instrument .
185. Goals of Isolation
1. Moisture Control
Excluding sulcular fluid, saliva, and gingival bleeding from the
operating field.
2. Retraction and Access
It provides maximal exposure of the operating site and usually
involves maintaining an open mouth.
3. Harm Prevention
It prevents the patient from being injuried during the
operative procedure
Small instruments and debris can be aspirated or swallowed.
186. Materials Used for Moisture Control:
I. Rubber Dam Isolation
I. Cotton Roll Isolation & Cellulose Wafers
II. Other Isolation Techniques
Isolation of the Operating Field
187. I. Rubber Dam Isolation
It ensures appropriate dryness of the teeth & improves the
quality of clinical dental procedures, by defining the
operating field.
Advantages:
Dry, Clean Operating Field
Improved Access and Visibility
Improved Properties of Dental Materials
Protection of the Patient and Operator
188. Disadvantages
Time consumption and patient objection are the most frequently
quoted disadvantages of the rubber dam.
Certain oral conditions may preclude the use of the rubber dam;
1. Some third molars,
2. psychologic reasons
3. Partially erupted teeth
4. Patients suffering from asthma
5. Extremely malpositioned teeth.
6. Latex allergy
I. Rubber Dam Isolation
189. II. Cotton Roll Isolation
& Cellulose Wafers
Absorbents (cotton rolls, cellulose wafers, gauze
sponges).
Using a saliva ejector in conjunction with absorbents
may further abate salivary flow.
The assistant has the responsibility of keeping dry
cotton rolls in the mouth.
Position: Placed in the facial vestibule for maxillary
teeth & in the lingual vestibule (between the teeth)
and the tongue for mandibular teeth.
190. II. Cotton Roll Isolation
& Cellulose Wafers
Many commercial devices for holding cotton rolls in
position are available.
191. III. Other Isolation Techniques
1) High-Volume Evacuators & Saliva Ejectors
2) Mirror and Evacuator Tip Retraction
3) Throat Shields
4) Retraction Cord
5) Mouth Props
6) Drugs
193. Rubber Dam Application
Materials &Instruments
1) Rubber dam Sheet
Sterile Rubber dam is also available packaged as
individual sheets in different:
Sizes:
5X5 inch or 6X6 inch
Colour:
light and dark dam material
shiny and a dull side.
Thickness:
thinner material → passing through the contacts easier.
thicker dam → retracting tissue & resistant to tearing.
194. Rubber Dam Application
Materials &Instruments
1) Rubber dam Sheet
2) Retainer Forceps
It is used both for placement and removal of the retainer
from the tooth
195. Rubber Dam Application
Materials &Instruments
1) Rubber dam Sheet
2) Retainer Forceps
3) Retainer (Clamp)
It is used to anchor the dam to the
tooth and retract gingival tissue.
It consists of four prongs and two jaws connected by a bow,
with the presence of wings some times.
Special consideration:
Stability and retention test.
Stretching the retainer for long periods should be avoided.
Dental floss should be tied to the bow of the retainer or
both holes of the jaws
196. Rubber Dam Application
Materials &Instruments
1) Rubber dam Sheet
2) Retainer Forceps
3) Retainer
4) Holder
It is a U-shaped metal / plastic frame with small
projections.
Position → outside the dam
Curvature → concentric & parallel to the patient's face.
An optional adjustable neck strap.
197. Rubber Dam Application
Materials &Instruments
1) Rubber dam Sheet
2) Retainer Forceps
3) Retainer
4) Holder
5) Punch
It is a precision instrument having a rotating metal
table (disk) with six holes of varying sizes and a
tapered, sharp-pointed plunger.
The plunger should be centered in the cutting hole so
the edges of the holes are not at risk of being chipped
by the plunger tip when the plunger is closed.
198. Rubber Dam Application
Materials &Instruments
1) Rubber dam Sheet
2) Retainer Forceps
3) Retainer
4) Holder
5) Punch
6) Lubricant
A water-soluble lubricant applied in the area of the
punched holes facilitates the passing of the dam septa
through the proximal contacts.
If commercial products are unavailable, other lubricants,
such as shaving cream or soap slurry, are also satisfactory.
Cocoa butter or petroleum jelly may be applied at the
corners of the patient's mouth to prevent irritation.
199. Rubber Dam Application
Materials &Instruments
1) Rubber dam Sheet
2) Retainer Forceps
3) Retainer
4) Holder
5) Punch
6) Lubricant
7) Napkin
It is placed between the rubber dam and the patient's skin,
particularly for long appointments, due to the following
advantages:
It prevents skin contact with rubber.
It absorbs any saliva seeping at the corners of the mouth.
It provides a convenient method of wiping the patient's lips
on removal of the dam.
200. Rubber Dam Application
Materials &Instruments
1) Rubber dam Sheet
2) Retainer Forceps
3) Retainer
4) Holder
5) Punch
6) Lubricant
7) Napkin
8) Anchore
The proximal contact
Waxed dental tape (or floss) or a small piece of rubber dam
material (cut from a sheet of dam).
The material used should be trimmed to approximately 0.5
inch in total length to prevent interference with the
operating site.
201. Isolation is either:
Single isolation
Multiple isolation
The distance between holes is equal to the distance
from the center of one tooth to the center of the adjacent
tooth, measured at the level of the gingival tissue.
Generally, this is approximately 1/4inch (6.3 mm).
Holes size: use the smaller holes for the incisors,
canines, and premolars and the larger holes for the
molars. The largest hole is generally reserved for the
posterior anchor tooth.
Rubber Dam Application
Hole Number, Size &Position
202. Holes position: should follow the arch form, making
adjustments for malpositioned or missing teeth.
For maxillary teeth, the holes are positioned
approximately 1 inch (25 mm) from the superior
border of the dam,
For mandibular teeth, mentally divide the rubber
dam into three vertical sections: left, middle, and
right.
For first premolar.
For first molar.
For second or third molar.
Rubber Dam Application
Hole Number, Size &Position
203. Consideration:
For Class V lesion, the tooth hole should be punched
slightly facial to the arch form.
Rubber Dam Application
Hole Number, Size &Position
A rubber stamp is available that
imprints both permanent and
primary arch forms on the rubber
dam.
A plastic template can also be used to
mark hole position.
204. I. Applying the Retainer Before the Dam
II. Applying the Dam Before the Retainer
III. Applying the Dam and Retainer Simultaneously
Rubber Dam Application
Techniques:
205. (1) (2) (3)
(4) (5) (6)
Rubber Dam Application
I. Applying the Retainer Before the Dam
206. (7) (8) (9)
(10) (11) (12)
Rubber Dam Application
Applying the Retainer Before the Dam
207. Advantage:
To reduce the risk of the retainer being swallowed or
aspirated before the dam is placed.
To solves the occasional difficulty of trying to pass the
dam over a previously placed retainer.
Rubber Dam Application
II. Applying the Dam Before theRetainer
208. Advantage:
There is no need to manipulate the dam over the
retainer.
Disadvantage:
Reduction in visibility of underlying gingival tissue.
Rubber Dam Application
III. Applying the Dam &the Retainer Simultaneously
210. Errors in Application and Removal
Off-center arch form:
Inappropriate distance between the holes:
Too little
too much
Incorrect hole size:
Inappropriate retainer:
212. Definition of tooth preparation
Mechanical alteration of defective, injured, or diseased
tooth to best receive restorative material that will
reestablish healthy state, including esthetic corrections,
along with normal form and function.
213. Objective of tooth preparation
1) Remove all defects and provide necessary protection to the
pulp
2) Extend the restoration as conservatively as possible.
3) Form the tooth preparation so under force of mastication,
Tooth or Restoration will not fracture and not be displaced.
4) Allow for esthetic and functional placement of a restorative
material.
214. Stages and steps of tooth preparation
May facilitate better adherence to preparation principles
and pulpal protection for all operators,
It is particularly beneficial in an academic setting.
Divided into two stages :
1) Initial tooth preparation stage.
2) Final tooth preparation stage .
215. Stages and steps of tooth preparation
1) The Initial tooth preparation stage:
Mechanical alterations of tooth are extended to sound
tooth structure in all directions (facially, lingually,
gingivally, incisally or occlusally, mesially, and distally) .
216.
217. Stages and steps of tooth preparation
2) The final tooth preparation stage:
Excavating any remaining, infected carious dentin.
Removing old restorative material if indicated.
Protecting the pulp.
Incorporating additional preparation design features
that minimize tooth or restoration fracture against
oblique forces .
219. Factors influencing cavity preparation
2- knowledge of dental anatomy :
Direction of enamel rods.
Thickness of enamel.
Dentin body.
Size & position of the pulp.
220. Factors influencing cavity preparation
3- patient factors:
Economic status.
Age.
4- Restorative material factors:
The patient's input into the decision is important.
Economic and esthetic values are primary patient
decisions.
The ability to isolate the operating area.
221. Factors influencing cavity preparation
3- patient factors:
Economic status.
Age.
4- Restorative material factors:
The patient's input into the decision is important.
Economic and esthetic values are primary patient
decisions.
The ability to isolate the operating area.
222. Factors influencing cavity preparation
5) Conservation of tooth structure
Minimal extensions of the tooth preparations .
Supragingival margins .
Rounded internal line angles.
224. Tooth preparation terminology
Internal Wall:
internal wall is a prepared (cut) surface that does not
extend to the external tooth surface
External Wall:
An external wall is a prepared (cut) surface that extends
to the external tooth surface, and such a wall takes the
name of the tooth surface (or aspect) that the wall is
toward.
225. Tooth preparation terminology
Axial wall
An axial wall is an internal wall parallel with the long axis
of the tooth.
Pulpal wall
A pulpal wall is an internal wall that is both perpendicular
to the long axis of the tooth and occlusal of the pulp.
226. Tooth preparation terminology
Floor (or Seat)
A floor (or seat) is a prepared (cut) wall that is reasonably
flat and perpendicular to those occlusal forces that are
directed occlusogingivally (generally parallel to the long
axis of the tooth).
227. Examples are the pulpal and gingival walls. Such floors
may be purposefully prepared to provide stabilizing
seats for the restoration, thus distributing the stresses
in the tooth structure, rather than concentrating them.
This increases the resistance form of the restored
tooth against post-restorative fracture.
228. Tooth preparation terminology
Enamel Wall
The enamel wall is that portion of a prepared external
wall consisting of enamel.
Dentinal Wall
The dentinal wall is that portion of a prepared external
wall consisting of dentin, in which mechanical retention
features may be located
229. Tooth preparation angles
Line Angle
A line angle is the junction of two planal surfaces of
different orientation along a line.
An internal line angle
is a line angle whose apex points into the tooth.
An external line angle
is a line angle whose apex points away from the tooth.
Point Angle
A point angle is the junction of three planal surfaces of
different orientation.
230. Cavosurface Angle and Cavosurface Margin
The cavosurface angle is the angle of tooth structure
formed by the junction of a prepared (cut) wall and the
external surface of the tooth. The actual junction is
referred to as the cavosurface margin
231. Tooth preparation terminology
Simple Tooth Preparations.
If only one tooth surface is involved .
compound Tooth Preparations.
If two surfaces are involved .
Complex Tooth Preparations.
For a preparation involving three (or more) surfaces
233. Tooth preparations design
1- Conventional design preparation.
Typical for amalgam restoration and includes the
following :
Uniform pulpal and/or axial wall depths.
Cavosurface margin design that results in 90°
restoration margin.
Primary retention form derived from occlusally
converging vertical walls.
234. Tooth preparations design
1- Conventional design preparation.
Typical for amalgam restoration and includes the
following :
Uniform pulpal and/or axial wall depths.
Cavosurface margin design that results in 90°
restoration margin.
Primary retention form derived from occlusally
converging vertical walls.
235.
236. Tooth preparations design
2- Beveled Conventional designs.
are characterized as conventional preparations with
beveling of some accessible enamel margins.
237. Tooth preparations design
3- Modified preparation designs :
may not have uniform axial or pulpal depths or
occlusally converging vertical walls.
Amalgam tooth preparations only use conventional
designs, whereas composite preparations may be any
of the three designs.
238. Classification of tooth preparations
Class I Caries : pit and fissure, on occlusal, buccal,
and lingual surfaces of posterior teeth, and Lingual of
anterior teeth.
Class II Caries: affecting proximal surfaces of molars
and premolars.
Class III Caries : proximal surfaces of centrals,
laterals, and cuspids.
239. Classification of tooth preparations
Class IV Caries : proximal including incisal edges of
anterior teeth.
Class V Caries : gingival 1/3 of facial or lingual surfaces
of anterior or posterior teeth.
Class VI :(never described by Black, added later by
others) Caries : cusp tips of molars, premolars, and
cuspids
242. Stages of tooth preparation
Final Tooth Preparation Stage
Step 5: Removal of any remaining infected dentin
and/or old restorative material, if indicated .
Step 6: Pulp protection, if indicated.
Step 7: Secondary resistance and retention forms.
Step 8: Procedures for finishing external walls.
Step 9: Final procedures: cleaning, inspecting,
sealing.
243. Initial Tooth Preparation Stage
Step 1: Outline form and initial depth.
1) Placing Prep. margins in the positions they will occupy
in the final preparation .
2) Preparing initial depth of 0.2 to 0.8 mm pulpally of DEJ
position.
244. Initial Tooth Preparation Stage
Principles of establishing the outline form :
1) all friable and/or weakened enamel should be removed .
2) all faults should be included.
3) all margins should be placed in a position to afford good
finishing of the margins of the restoration.
245. Initial Tooth Preparation Stage
Step 2: Primary Resistance Form.
1) Is that shape and placement of the preparation
walls that best enable both restoration and tooth to
withstand, without fracture, masticatory forces
delivered principally in the long axis of the tooth.
2) The relatively flat pulpal and gingival walls
prepared perpendicular to the tooth's long axis help
resist forces in the long axis of the tooth and
prevent tooth fracture from wedging effects .
246. Initial Tooth Preparation Stage
Step 2: Primary Resistance Form.
1) Is that shape and placement of the preparation
walls that best enable both restoration and tooth to
withstand, without fracture, masticatory forces
delivered principally in the long axis of the tooth.
2) The relatively flat pulpal and gingival walls
prepared perpendicular to the tooth's long axis help
resist forces in the long axis of the tooth and
prevent tooth fracture from wedging effects .
247. Obtaining Primary Resistance Form.
1) Use the box shape with relatively flat floor .
2) to restrict the extension of the external walls as small
as possible to allow strong cusp and ridge areas .
3) to have a slight rounding of internal line angles to
reduce stress concentrations .
248. Obtaining Primary Resistance Form.
4) in extensive tooth preparations, to cap weak cusps and
envelope or include enough of a weakened tooth within
the restoration.
5) to provide enough thickness of restorative material to
prevent its fracture under load.
6) to bond the material to tooth structure when
appropriate.
249. Step 3: Primary Retention Form
1) Is that shape or form of the conventional preparation
that resists displacement or removal of the restoration
from tipping or lifting forces.
2) Retention form and resistance form are accomplished in
the same cutting procedure .
3) For amalgam restorations in most Class I and all Class
II the external tooth walls converge occlusally .
250. Step 4: Convenience Form
is that shape or form of the preparation that provides for
adequate observation, accessibility, and ease of operation
in preparing and restoring the tooth.
251. FINAL TOOTH PREPARATION STAGE
Step 5: Removal of Any Remaining Enamel Pit or Fissure,
Infected Dentin, and/or Old Restorative Material, if
Indicated.
Step 6: Pulp Protection, if Indicated (Placement of liners
and bases).
is not a step in tooth preparation in the strict sense of the
word, it is a step in adapting the preparation for receiving
the final restorative material.
Step 7: Secondary Resistance and Retention Forms.
252. FINAL TOOTH PREPARATION STAGE
Step 8: Finishing the External Walls of the Tooth
Preparation.
Step 9: Final Procedures: Cleaning, Inspecting, and
Sealing
