Class 1- Principles of Operative Dentistry Flashcards
define operative dentistry
treatment of disease/defects of hard tissues of teeth that do not require full coverage restorations
what does operative dentistry restore
form, function and esthetics
describe enamel
hard, strong, and brittle
what percentage does hydroxyapatite make up of enamel
90-92%
how do diameter of enamel rods vary
larger near surface, smaller near dentin borders
what is the orientation of enamel rods
perpendicular to long axis
decsribe enamel tufts
-hypomineralized
-extend into enamel
describe enamel lamellae
-thin faults between enamel rod groups
what are enamel spindles
odontoblastic process crossed into enamel
describe the DEJ
hypomineralized zone where dentin meets enamel
where does enamel become more soluble
closer to the DEJ
what does fluoride do to acid solutbility
lowers it
what is the largest portion of the tooth
dentin
what forms the walls of pulp chamber
dentin
when is dentin formed
immediately prior to enamel
how long does dentin formation continue
throughout the life of the pulp
what is between dentin tubules
intertubular denin
where is the diameter of tubules the largest
at the pulp
where is the number of dentin tubules the largest
at pulp
what is reparative dentin formed by and in response to what
formed by secondary odontoblasts at the end of tubules at surface of pulp in response to moderate irritant
what is sclerotic dentin
primary dentin that has changed, peritubular dentin widens and fills with calcified material
how does the hardness of dentin compare to enamel
hardness is 1/5 of enamel
where is dentin harder
near DEJ compared to pulp
what percent hydroxyapatite is dentin
50%
what causes dentinal sensitivity
fluid movement in tubules
explain the 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 and distortion in nerve endings -> pain
when is the smear layer created and what does it do
created when tooth is cut/prepared
- plugs dental tubules
what does the color of enamel depend on and when does it become temporarily whiter
depends on underlying dentin and becomes temporarily whiter when dehydrated
what is the color of enamel? dentin?
-enamel-gray
-dentin- yellow white
how often is cementum formed
continually
define contour
curve or shape of something
define proximal contact
where two adjacent teeth contact
define embrasures
an opening with sides flaring outward, V-shaped valleys between adjacent teeth
what are the 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
what are prep walls designed to do
retain restoration and resist fracture
what are the goals of preparation
-remove remaining caries or old restorative material
-protect pulp
-minimize fracture, maximize retention
-finish walls and margins
- final cleaning, inspection, sealing prep
what factors should be considered in operative dentistry
-esthetics
-economics
-medical condition
-age
-caries risk
what factors should be considered in dental anatomy
-enamel rod orientation
-thickness of enamel and dentin
- size and location of pulp
-relationship of tooth to periodontium
what are residual caries
caries left by operator
when would it be acceptable to leave residual caries
to avoid pulp exposure when left as affected dentin near the pulp
describe acute caries vs chronic caries
acute: or rampant, light color, appears dull and mushy
chronic: slow or arrested, dark color, appears shiny and solid
how many surfaces are involved in simple vs compound vs complex
-simple: 1
-Compound: 2
-complex: 3 or more
where is the axial wall located
parallel to long axis of tooth (vertical)
where is the pulpal wall located
perpendicular to long axis of tooth (horizontal)
what do pulpal and gingival floors/walls do
-provide stabilizing seats for restoration
- distribute stresses in tooth
what is a line angle
junction of two walls/surfaces along a line
internal apex points ____ from observer. external apex points ____ observer
-away
- towards
what is a point angle
joining of three surfaces
what is cavosurface
where prepared tooth meets unprepared tooth
what is enamel margin strength formed by
full length enamel rods
what is unsupported enamel
when enamel rods are not supported by sound dentin
what is a class 1
-occlusal surface of posterior teeth
-can include lingual/ buccal grooves and pits
what is a class II
proximal surfaced of premolars and molars
what is a class III
proximcal surfaces of incisors and canines
what is a class IV
proximal and incisal edges of incisors and canines
what is a class V
gingival 1/3 of smooth surfaces (buccal and lingual)
what is a class VI
incisal edge or cusp
what are the stages of tooth preparation
initial stage and outline form
what is the initial stage
-outline form
-initial depth
-primary resistance form
- primary retention form
- convenience form
what is important in outline form
-undermined enamel removed
- margins placed where you can finish restoration
- no occlusion on margins of prep
- preserve strength of cusps and marginal ridges
- minimize extensions facioloingually
what is the outline form of a class I
- depth of pit and fissure maximum of 2 mm
when do you connect two preps
when they are less than 0.5 mm apart
what is the outline form of a class 2
-extend gingival margins apical to contact, extend interproximal margins to embrasures
- axial wall depth 0.2-0.8 mm into dentin
what is an enameloplasty
removing shallow enamel fissure or pit
how much is removed in an enameloplasty
no more than 1/3 enamel thickness
what is resistance form
- resistant to fracture
- leave dentin support
-preserve cusps and marginal ridges
when is resistance form compromised
- when margin exceeds 2/3 distance between central grooves
- when margins end 1/3 distance between central groove and cusp tip
what should you do to internal and external line angles and why
slightly round them for less stress concentration
what do flat floor prevent
movement
what do bevels do
-remove unsupported enamel
- reduce stress concentration
what should margins be in amalgam
90 degrees
what do dovetails do
prevent tipping and proximal displacement
what do taller walls resist
pull of sticky foods
what is convergence
walls slant towards each other
what is involved in the final stage of tooth prep
-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
describe affected dentin vs infected dentin
-affected dentin is demineralized and usually discolored but NOT soft and is ok to leave
- infected dentin microorganisms are present, soft, may or may not be stained, must remove
what are examples of secondary retention
-retention grooves, points
why do you bevel for rounded axiopulpal line angle
-increase bulk of restorative material, disperse concentration of forces
what is 8:00 position for
-buccal side of patients UL
-lingual side of patients LR
what is 11:00 positioning for
-buccal side of patients UP
- lingual side of patients LL
what is 12:00 positioning for
-buccal sides of patients R and L anterior
-lingual sides of patients R and L anterior
