Principles of Operative Dentistry Flashcards
what is operative dentistry?
treatment of disease/defect of hard tissues of teeth that do not require full coverage restoration
what does operative dentistry do?
restores form, function, and esthetics
enamel thickness varies by (2)
location
tooth type
enamel is –% hydroxyapatite
90-92
enamel is (2)
strong and brittle
enamel rod diameter
larger near surface, smaller near dentin borders
how are enamel rods oriented?
perpendicular to long axis, radiate outward (like spokes on a wheel)
do not leave — enamel
unsupported
grooves and fissures can act as a
food/bacteria trap (leads to decay)
Enamel Tufts (2)
◦Hypomineralized
◦Extend into enamel
Enamel lamellae (2)
◦Thin faults between enamel rod groups
◦ Extend from enamel toward DEJ
Enamel Spindles
◦Odontoblastic process crossed into enamel
Dentino-Enamel Junction
◦Hypomineralized Zone where dentin meets enamel
enamel solubility
more soluble as your approach DEJ
how does fluoride impact acid solubility of enamel?
it lowers acid solubility, important to remember both when considering caries and when considering bonded restorations
pulp-dentin complex (2)
stron and resilient
living tissue
pulp-dentin complex (2)
stron and resilient
living tissue
largest portion of the tooth
dentin
dentin is located in both
coronal and root portions of tooth
dentin forms the walls of
pulp chamber
dentin is formed immediately — to enamel
prior
dentin formation continues throughout the
life of the pulp
dentinal tubules canals extend from
DEJ/CEJ to pulp
dentinal tubules are lined with
peritubular dentin
— is located between dentinal tubules
interdentin
diameter of dentinal tubules is largest at the
pulp
number of dentinal tubules/square mm is greatest at the
pulp
reparative dentin is formed by
secondary odontoblasts
reparative dentin is a response to
moderate irritant
sclerotic dentin (2)
primary dentin that has changed
peritubular dentin widens and fills with calcified material
dentin hardness
averages 1/5 that of enamel
dentin is harder near
DEJ than pulp (3x)
dentin is –% hydroxyapatite
50
dentinal sensitivity
fluid movement in tubules
Hydrodynamic Theory of Pain Transmission
◦Odontoblastic process wrapped in nerves and fluid in dentinal tubules
◦Enamel/cementum removed during preparation= seal is lost
◦ Causing small fluid movements in tubules= distortions in nerve endings
◦ = PAIN
smear layer is created whenever
tooth is cut/prepared
smear layer plugs
dentinal tubules
enamel (4)
◦Gray, semi-translucent
◦Color depends on underlying dentin
◦Becomes temporarily whiter when dehydrated
◦Shiny
dentin color (2)
◦Yellow-white
◦Dull, opaque
cementum (3)
- Covers root surface
- Softer than dentin
- Formed continually
CONTOURS
Curve or shape of something
Overcontour vs overcontoured
Overcontour: flat
overcontoured: bulky
PROXIMAL CONTACT
Where two adjacent teeth contact (Vs occlusal contact)
EMBRASURES
an opening with sides flaring outward
In dentistry, V-shaped valleys between adjacent teeth
◦ Gingival usually fills in this space
SKIPPED
Objectives of Tooth Preparation (6)
- Resistance Form, Retention Form, Convenience form
- Remove defects
- Provide necessary protection to pulp
- Extend restoration as conservatively as possible
- Resist fracture when chewing
- Restore esthetics and function
tooth prep should be precise, especially for
amalgam
GV black
prep design and principles
preparations for composite restorations incorporate
bonding
Preparation
Extend to sound tooth structure in all directions
Prep walls are designed to (2)
◦ RETAIN restoration
◦ RESIST fracture
Preparation (5)
- Remove remaining caries or old restorative material
- Protect pulp
- Minimize fracture, maximize retention
- Finish walls and margins
- Final cleaning, inspection, sealing prep
Factors to consider (5)
Esthetics Economics Medical Condition Age Caries risk
Dental Anatomy (4)
◦Enamel Rod orientation
◦Thickness of enamel and dentin
◦Size, location of pulp
◦Relationship of tooth to periodontium
Factors to consider (3)
- Caries
- Fractured teeth
- Improve form and function
Conservation of Tooth Structure
Repair damage but preserve vitality
Locations of Primary Caries (3)
pit and fissure
enamel smooth surface
root surface
Pit and Fissure occur from
imperfect coalescence of developmental enamel lobe
Area left unclean chronically
Enamel Smooth Surface
Locations of Primary Caries (3)
pit and fissure
enamel smooth surface
root surface
Locations of Primary Caries (3)
pit and fissure
enamel smooth surface
root surface
residual caries
caries left by operator (intentional or accident)
never ideal to leave caries, especially when left at the
DEJ or on prepared enamel wall
residual caries may be acceptable in rare instances to
avoid pulp exposure (when left has affected dentin near the pulp)
Recurrent Caries
Microleakage present at the junction between restoration and tooth
Recurrent Caries may progress under or behind restoration so it can’t be
seen with a radiograph
Reparative Dentin
Formed by odontoblasts at end of tubules at surface of pulp
Reparative Dentin is formed in response to
irritation
rate of caries (2)
acute
chronic
acute (3)
◦Or “rampant”
◦Light color
◦Appears dull, mushy
chronic (3)
◦Slow or arrested
◦Dark color
◦Appears shiny, solid
Dentists formerly practiced “extension for prevention.”
This meant
taking away unnecessary tooth structure and is no longer practiced
Better preventative measures available (4)
Enameloplasty,
sealant,
preventive resin
or conservative composite restoration instead
Simple -
one surface involved
Compound -
two surfaces
Complex -
three or more surfaces of tooth involved
O =
occlusal
MO or DO or MOD -
mesial occlusal or distal occlusal, mesial-occlusal distal
F or B -
facial or buccal
L –
lingual
Internal Walls (2)
◦ Axial Wall
◦ Pulpal Wall or Floor
Axial wall is — to long axis of tooth
PARALLEL
PULPAL WALL/FLOOR
wall closest to pulp
PULPAL WALL/FLOOR is — to long axis of tooth in Class I and II preparations
PERPENDICULAR
Floor (4)
◦PREPARED (cut) wall
◦FLAT
◦PERPENDICULAR to occlusal forces
◦Pulpal and gingival floor/walls
Pulpal and gingival floors/walls provide (1) and distribute (1)
Provide stabilizing seats for restoration
distribute stresses in tooth
Line Angle
Junction of two walls/surfaces along a line
Internal-
apex points AWAY from observer
External-
apex points TOWARD observer
Point angle
Junction of three surfaces
CAVOSURFACE angle or margin
◦ Junction of PREPARED cavity wall and EXTERNAL surface of tooth
◦ Keep in mind: location of tooth, direction of enamel rods, material you will be using
types of CAVOSURFACE angle or margin (3)
◦ Bevel
◦ 90 ̊
◦ Chamfer
CEJ◦ Cementoenamel Junction
◦ Where cementum meets enamel
Enamel Margin Strength is formed by
full length enamel rods
Enamel Margin Strength
Enamel rods’ inner ends are on sound dentin
UNSUPPORTED ENAMEL
When enamel rods are not
supported by sound dentin
what to do with unsupported enamel
remove from prep, brittle and fracture easily
Classifications of Tooth Preparations name is based on
anatomy involved
Class I (2)
◦ Occlusal surface of posterior teeth
◦ May include lingual/buccal grooves and pits
Class II
◦ Proximal surfaces of premolars and molars
Class III
◦ Proximal surfaces of incisors and canines
◦ That do not involve incisal edge
Class IV
◦ (See Class III, add incisal edge)
Class V
◦ Gingival 1/3 of smooth surfaces
◦ Buccal, lingual
Class VI
◦ Incisal edge or cusp
Initial Stage (5)
- Outline Form
- Initial depth
- Primary resistance form
- Primary retention form
- Convenience form
Visualize OUTLINE FORM (2)
◦smooth and flowing
Undermined enamel —
removed
— placed where you can finish restoration
Margins
No — on margins of preparation
occlusion
Preserve strength-
cusps and marginal ridges
Minimize extensions —
faciolingually
Connect two preps that are
0.5
Class I- Depth of pit and fissure maximum –mm (in lab setting)
2.0
extend class 1 to
sound tooth structure
extend class 1 when (2)
◦ Fissures cannot be eliminated by enameloplasty
◦ Two cavities have <0.5mm between them
Do not terminate class 1 on (2)
cusp height or ridge crest
Allow sufficient access for class 1 (2)
placement and finishing
Class II- extend gingival margins —, extend interproximal margins to —
apical to contact
embrasures
class 2 Axial Wall Depth
0.2-0.8mm INTO DENTIN
◦ 1.0-1.5 mm on manikin
Axial Wall Depth is measured from the
tooth (proximal surface) to the axial wall
◦ It is NOT a typical depth measurement from the top of something to the bottom
Enameloplasty
Remove shallow enamel fissure or pit
◦ Creates smooth, saucer shaped surface= self-cleansing
◦ NO MORE THAN 1/3 ENAMEL THICKNESS REMOVED
RESISTANCE TO FRACTURE
• Objectives are to resist fracturing the tooth or restorative material
Need to resist or withstand — forces
occlusal
Conservative extension-
leave strong tooth
• Remember dentin support
Preserve (2)
cusps and marginal ridges
When margin exceeds 2/3 of the distance between central groove and cusp tip
MUST CAP WEAK CUSPS
When margins end ½ distance between central groove and cusp tip
CONSIDER CAPPING WEAK CUSPS
Resistance Form (3)
- Internal line angles slightly rounded
- External line angles slightly rounded
- Accomplish with bevel at axiopulpal line angle
- = LESS STRESS CONCENTRATION
- Flat floors
- Prevents movement
Allow for sufficient thickness of restorative material
◦Amalgam —mm minimum
◦Gold —mm minimum depending on area
◦Porcelain —mm minimum
1.5
1-2
2.0
Bevels when needed to (2)
◦ Remove unsupported enamel
◦ Reduce stress concentration
Margins- – ̊ in amalgam
90
RETAIN THE RESTORATION
◦Objectives of this are to
keep restoration in the tooth
Dovetail prevents (2)
tipping and proximal displacement
retention form (3)
wall length
converenge
parallelism
Wall length
• Taller wall = resists pull of sticky foods
Convergence (2)
- Walls slant toward each other
* Especially important with amalgam
retention form (3)
wall length
converenge
parallelism
What about bonded restorations? (2)
- Micromechanical retention between adhesive and tooth
* Some of these principals become less important, but are still followed
Convenience Form
FORM THAT ALLOWS YOU TO ACCESS THE DEFECT
Convenience Form allows you to
see what youre doing, ideally with perfect ergonomics
Once outline form, primary resistance, and primary retention form are
complete, caries may
remain- REMOVE THE CARIES
Final stage of Tooth Preparation: (6)
- Remove remaining infected dentin
- Remove remaining old restoration
- Pulp protection
- Secondary resistance and retention forms
- Finish external walls and margins
- Final cleaning, inspecting, and sealing
Affected dentin-
demineralized
◦ Usually discolored but NOT soft
◦ OK to leave
Infected dentin-
microorganisms present
◦ Soft
◦ May or may not be stained
◦ MUST REMOVE. (there are MICROORGANISMS PRESENT.)
How to tell the difference between affected and infected dentin?
◦ Not always possible
Retention grooves, points
Areas for restorative material to “lock”into, results in improved retention
Secondary Resistance fewer
extensions
secondary resistance
Bevel for rounded axiopulpal line angle to
increase bulk of restorative material, disperse concentration of forces
8:00 position (4)
◦ Slightly to the patient’s right and front
◦ Patient tilting head slightly to right
◦ Buccal sides of patient’s UL
◦ Lingual sides of patient’s LR
11:00 position (4)
◦ Slightly to the patient’s right and behind
◦ Patient tilting head slightly to left
◦ Buccal sides of patient’s UR
◦ Lingual sides of patient’s LL
12:00-1:00 position (4)
◦ Slightly to the patient’s left and behind
◦ Patient’s head tilted back
◦ Buccal sides of patient’s R and L anterior
◦ Lingual sides of patient’s R and L anterior
