1/18: Operative Dentistry I Flashcards
What is operative dentistry?
Treatment of disease/defects of hard tissues of teeth that DO NOT REQUIRE FULL COVERAGE
RESTORATION
What does operative dentistry restore?
Form, function, and esthetics
What are the 4 types of teeth?
Incisors
Canines
Premolars
Molars
What does enamel thickness vary based on?
Location
Tooth type
What makes up enamel?
90-92% hydroxyapatite
Describe enamel
Strong and brittle
Where are enamel rods diameter larger and smaller?
Larger- near surface
Smaller- near dentin borders
Where are enamel rods found?
Perpendicular to long axis, radiate outward (like spokes on a wheel)
_______ leave unsupported enamel
DO NOT
What can grooves and fissures act as?
Food/bacterial trap
What do grooves and fissures lead to?
Decay
Where do enamel tufts extend into?
Enamel from DEJ
What are enamel lamellae?
Thin faults between enamel rod groups
What mineralization are enamel tufts?
Hypomineralized
Where do enamel lamellae extend from?
Enamel toward DEJ
What is the DEJ?
Dentino-enamel junction
Where is the DEJ located?
Hypomineralized zone where dentin meets enamel
Where is the solubility of enamel increased?
As you approach DEJ
What does fluoride do?
Lowers acid solubility
*important to remember both when considering caries AND when considering bonded restoration
Describe the pulp-dentin complex
Strong and resilient
Living tissue
What is the largest portion of the tooth?
Dentin
Where is dentin located?
In both coronal and root portions of tooth
What does dentin form?
Walls of pulp chamber
When is dentin formed?
Immediately prior to enamel
When does dentin formation continue throughout?
The life of the pulp
What are enamel spindles?
Odontoblastic process crossed into enamel
What can enamel spindles serve as?
Pain receptors
What are dentinal tubules?
Canals extending from DEJ/DCJ to pulp
What are dentinal tubules lined with?
Peritubular dentin
What kind of dentin is between tubules?
Intertubular dentin
Where is the diameter of tubules largest?
At pulp
Where is the number of tubbules/square mm greatest?
At pulp
What is reparative dentin formed by?
Secondary odontoblasts
What do reparative dentin respond to?
Moderate irritant
What is sclerotic dentin?
Dentin that has changed
What kind of dentin widens and how?
Peritibular; filled with calcified material
The hardness of dentin averages _____ that of enamel
1/5
Where is dentin harder near?
DEJ than near pulp (3x)
What percent of dentin is hydroxyapatite?
50%
What causes dentinal sensitivity?
Fluid movement in tubules
What is the hydrodynamic theory of pain transmission?
Odontoblastic process wrapped in nerves and fluid in dentinal tubules
What happens when enamel/cementum removed during preparation?
Seal is lost
What happens during small fluid movements in tubules?
Distortions in nerve endings = PAIN
When is a smear layer created?
Whenever tooth is cut/prepared
What does a smear layer plug?
Dentinal tubules
- greatly reduces dentin permeability
Describe the color of enamel
Gray, semi-translucent
Color depends on underlying dentin
Becomes temporarily whiter when dehydrated
Shiny
Describe the color of dentin
Yellow-white
Dull, opaque
What does cementum cover?
Root surface
Describe the texture of cementum compared to dentin
Softer than dentin
Describe how cementum is formed
Continually
What is known as the curve or shape of something?
Contours
overcontour vs. overcontoured
What is known as where two adjacent teeth contact?
Proximal contact
vs. occlusal contact
What is known as an opening with sides flaring outward?
Embrasures
V-shaped valleys between adjacent teeth
(gingival usually fills in this space)
What are objectives of tooth preparation
*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 preparation should be _______
precise (especially for amalgam)
Who developed the preparation design and principles?
GV black
What do preparations for composite restorations incorporate?
Bonding
Where to preparations extend to?
Sound tooth structure in all directions
What are prep walls designed to?
RETAIN restoration
RESIST fracture
What do you do in a preparation?
- Remove remaining caries or old restorative material
- protect pulp
- minimized fracture, maximize retention
- finish walls and margins
- final cleaning, inspection, sealing prep
What are some external factors to consider when completing a restoration?
Esthetics
Economics
Medical condition
Age
Caries risk
What are some internal factors to consider when completing a restoration?
Dental anatomy
◦ Enamel Rod orientation
◦ Thickness of enamel and dentin
◦ Size, location of pulp
◦ Relationship of tooth to periodontium
Caries
Fractured Teeth
Improve form and function
How should you conserve the tooth structure?
Repair damage but preserve vitality
What are the three locations of primary caries?
Pit and fissure
Enamel smooth surface
Root surface
What do pit and fissure caries occur from?
Imperfect coalescence of developmental enamel lobe
What do enamel smooth surface occur from?
Area left unclean chronically
What are the 3 types of causes for residual caries?
Caries left by operator
- intentionally or by accident
Never ideal to leave caries
- Especially when left at the DEJ or on prepared enamel wall
May be acceptable in rare instance
- to avoid pulp exposure
- when left as affected dentin near the pulp
What are recurrent caries?
- Microleakage present at the junction between restoration and tooth
- may progress under the restoration or behind it so it cannot be seen with a radiograph
What is reparative dentin formed by?
Odontoblasts at end of tubules at surface of pulp (in response to irritation)
What are the two rates of caries?
Acute (or “rampant”)
Chronic
Describe acute rate of caries
Light color
Appears dull, mushy
Describe chronic rate of caries
Slow or arrested
Dark color
Appears shiny, solid
What did dentists formally practice?
“extension for prevention”
this meant taking away unnecessary tooth structure and is no longer practices
What are better preventative measures instead of “extension for prevention”?
Enameloplasty, sealant, and preventive resin or conservative composite restoration instead
What are these abbreviations:
O
MO or DO or MOD
F or B
L
O= occlusal
MO = mesial occlusal
DO = distal occlusal
MOD = mesial-occlusal distal
F or B = facial or buccal
L = lingual
What are the two internal walls that are prepped?
Axial wall
Pulpal wall or floor
Axial wall is _____ to the long axis of the tooth
Parallel
What is the cavosurface margin?
Margin (edge) where the prepared (cut) tooth meets the unprepared tooth
What is the cavosurface angle?
Angle where prepared wall and unprepared tooth surface meet
What is the wall closest to pulp?
Pulpal wall/floor
Where is the pulpal wall/floor?
Perpendicular to the long axis of tooth in class I and II preparations
What is the function of pulpal and gingival floors/walls?
Provide stabilizing seats for restoration
Distribute stresses in tooth
What is a line angle?
Junction of two walls/surfaces along a line
What is an internal line angle?
Apex points AWAY from observer
What is an external line angle?
Apex points TOWARD observer
What is a point angle?
Junction of three surfaces
What is a 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
What are the types of cavosurface angle or margin?
Bevel
90*
Chamfer
What is cavosurface?
Where prepared tooth meets unprepared tooth
What is the CEJ?
Cementoenamel junction
Where cementum meets enamel
What is enamel margin strength formed by?
Full length enamel rods
What is unsupported enamel?
When enamel rods are not supported by sound dentin
*remove for preparation (brittle, fracture easily)
Why operative dentistry?
Diagnosis
Treatment
Repair
What is a class I preparation?
Occlusal surface of posterior teeth
*may include lingual/buccal grooves and pits
What is a class II preparation?
Proximal surfaces of premolars and molars
What is a class III preparation?
Proximal surfaces of incisors and canines
*that do not involve incisal edge
What is a class IV preparation?
Same as class III, add incisal edge
What is a class V preparation?
Gingival 1/3 of smooth surfaces
buccal, lingual
What is a class VI preparation?
Incisal edge or cusp
What are the stages of tooth preparation?
Know what your restorative material needs for adequate strength
Initial stage
Final stage
What do you do during the initial stage of a tooth preparation?
Outline form
Initial depth
Primary resistance form
Primary retention form
Convenience form
What is axial wall depth?
Measured from the edge of the tooth (proximal surface) to the axial wall
*it is not a typical depth measurement from the top of something to the bottom
What is an enameloplasty?
Remove shallow enamel fissure or pit
*Creates smooth, saucer shaped surface = self-cleansing
How much enamel thickness is removed in an enameloplasty?
No more than 1/3
What must you do when margin exceeds 2/3 of the distance between central groove?
Must cap weak cusps
What must you do when margins end 1/2 distance between central groove and cusp tip?
Consider capping weak cusps
What creates less stress concentration?
Rounding externa lline angles
What do flat floors prevent?
Movement
When allowing for sufficient thickness of restorative material, what are minimum measurement thickness for amalgam, gold, and porcelain?
Amalgam 1.5mm minimum
Gold 1-2mm minimum depending on area
Porcelain 2.0mm minimum
What does a dovetail prevent?
Tipping and proximal displacement
What does a taller wall resist?
Pull of sticky foods
What does convergence mean?
Walls slant toward eachother
*especially important with amalgam
What do you do during the final stage of tooth preparation?
- 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
What kind of dentin is affected dentin?
Demineralized
- usually discolored but NOT soft
- ok to leave in rare circumstances
What kind of dentin is 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
Where should your position be when working on the buccal sides of patients UL and lingual sides of patient’s LR?
8:00 positioning
Where should your position be when working on the buccal sides of patients UR and lingual sides of patient’s LL?
11:00 positioning
Where should your position be when working on the patients buccal R and L anterior and lingual sides of patient’s R and L anterior?
12:00-1:00 positioning
