Final Study Guide Flashcards
What is sclerotic dentin?
Primary dentin that has changed
What happens when sclerotic dentin is placed?
Peritubular dentin widens, fills with calcified material
What is reparative dentin formed by?
Secondary odontoblasts at the end of the tubules at surface of pulp
What is reparative dentin formed in response to?
Moderate irritant, trauma, chronic irritation
What does reparative dentin provide protection to?
Underlying pulp by decreasing dentin permeability
Describe this diagram
What is a line angle?
Junction of 2 walls
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 3 walls
What is resistance?
Resistance to fracture (withstand occlusal forces)
How can you ensure you get ample resistance?
Conservative extension
Preserce cusps and marginal ridges
Internal/external line angles need to be beveled
Flat floors to precent restoration movements
What does a bevel reduce?
Stress
What should you do if the margin exceeds 2/3 distance of central groove?
Cap weak cusps
What should you do if margin ends 1/2 distance of central groove and cusp tip?
Consider capping cusps
What is retention?
Retains restoration during function
What can you do to ensure retention?
Convergence
Parallelism
Taller walls
Dovetail
What does a dovetail prevent?
Tipping and proximal displacement
Class I
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 involved the incisal edge
Class IV
Class III but with an added incisal edge
Class V
Gingival ⅓ of smooth surfaces
Buccal, lingual
Class VI
Incisal edge or cusp
Where are retention grooves placed in the box?
- just inside DEJ, entirely in dentin (do NOT go into gingival flor)
- at buccal/lingual axial line angle
Where are retention grooves placed in a class V?
- occlusal retention groove@ occlusal - axial line angle and gingival retention groove
- always in dentin just inside DEJ
Where do walls converge and diverge?
What is convergence for?
retention (isthmus/box walls)
What is divergence for?
Preserve the marginal ridge and ensure no undermined enamel
What is coppers role in amalgam?
Strength
What is the copper contents of conventional amalgam?
Low copper
What are qualities of high copper amalgam?
Superior to conventional
We use this
What does high copper amalgam eliminate? what does it add?
Gamma 2 phase = stronger restoration
Adds copper-tin phase
What does premature contact do to area?
Decreases area
What does premature contact do for occlusal force and stress?
Occlusal force stays the same but occlusal stress is increased
What is a result of premature contact?
Restoration failure
Pain/discomfort when biting
What is stress?
When load (force) is applied to material, stress is response
What are examples of stress?
- Protrusive movement
Anterior teeth
Flexure load on incisors - Posterior occlusion
Chewing = compressive load
At marginal ridge contact areas
At fossa areas - Occlusal stress = occlusal load (force) / occlusal contact area
- Tripodized occlusal contacts allows distribution of occlusal load across maximum area = minimal stress
What is compression?
Push
Stress necessary to fracture material by 2 forces OPPOSING eachother
What kind of load does compression require to cause failure?
Higher loads
What is the highest strength force?
Compression
What is the lowest type of force?
Tensile
What is tensile force?
Pull
Stress necessary to fracture a material by 2 opposing forces AWAY from eachother
When does tensile failure occur?
At lower loads
ex: laffy taffy
What is shear force?
Sliding
Stress that ruptures material of 2 opposing forces in different planes
What is intermediate between compressive and tensile force?
Shear
What is an example of shear force?
Implant-bone interface
What is torsion?
Twist
What is torsion used for?
To place implants (torque)
- torsion test on dental implants
- torsion fatigue on endo rotary files
What is flexural force?
Bending force
Stress to cause failure in bending
What is the test for flexure forces?
3 point bend test
- compressive load
- combo of compressive and tensile
What is flexural force vital due to?
Occlusal load
- on direct restrations (amalgam/composite)
- indirect/removable (everything that gets chewed on)
Describe biological properties
Biologic response when contact with human body
ex: gingivitis from plague
Describe surface properties
Material associated with surface
ex: denture retention, adhesive bonding
Describe physical properties
- type of atoms and bonding present in material
- size or shape have no effect
- structure insensitive
ex: optic (color, glass)
Thermal (conductive)
Describe mechanical properties
- reaction of a material to the application of an external force, size and shape affects properties
- structure sensitive
- applied force referred to as load
What bonds does amalgam have?
Metallic bonds
- cluster of positive metal ion surrounded by gas of electrons
- non directional bonds
- high electrical and thermal conductivity
What are the strength of metallic bonds?
High compressive strength and low tensile strength
What bonds does composite have?
Covalent bonds
- directional bonds
- low electrical and thermal conductivity
- water insoluble
How is a hollenback carver used?
- perpendicular to margins
- carve anatomy
- used on amalgam EARLY after its been condensed
What is calcium hydroxide?
Dycal
- stimulates reparative dentin formation
- placed with dycal instrument (tiny ball)
- liner
- often cover with resin modified glass ionomer
What is glass ionomer?
Vitrebond
- light cure
- releases fluoride over time
- use dycal instrument to place over area near pulp
- liner/base
What is a liner?
THIN layer over dentin
What is a base?
THICK layer on floor of prepared cavity
What is total etch?
Acid etch in a separate step from bond agent
What is selective etch?
Etch ONLY the enamel NOT dentin
What are the types of universal etch?
Etch and rinse
or Self etch
What is the chemical bonding of universal adhesives?
Game changer is 10-MDP
What is the mechanism of 10-MDP?
Phosphate monomer that chemically interacts via ionic bonding to Ca in hydroxyapartite
What is C factor?
Bonded/unbonded surfaces
What does an increase in C factor cause?
Increase stress
What does incremental placement do to C factor?
Decreases
- incremental placement doesn’t decrease shrinking it decreases stress
What does effective bonding and decrease C factor reduce?
Failure at interface
What allows you to add composite to just-cured composite without re-etching and bonding?
Oxygen inhibited layer
- oxygen in air interferes with polymerization
- facilitates bonding with next layer
What are components of the composite resin matrix?
- Difunctional monomers - 2 reactive ends to allow cross linking
- Bis-GMA
- UDMA
- TEGDMA
- BisGMA and TEGDMA: higher sorption as compared to UDMA
What are filler particles of composite?
Crystalline silica (quartz), Ba, Li, Al silicate glass, amorphous silica
What is the coupling agent of composite?
Silane
What is the activator and initiator of chemical or self cure?
Activator: tertiary amine
Initatory: benzoyl peroxide
What is the activator and initator for light cured?
Activator: blue light
Initatory: benzoyl peroxide
Name the parts of this
Face on non-cutting = cutting edge on cutting
Nib on non-cutting = blade on cutting
What is the shank angled?
to allow the cutting edge of the blade to be within the projected axis of the handle, allows force on blade without rotation
What are the benefits of double ended instruments?
More efficient
What are the benefits of single ended instruments?
Safer
What are the 3 p’s to fitness?
Posture
Positioning
Periodic stretching
What is ideal posture?
Maintain neutral position
- Head at 0-20 degree tilt- ears over shoulders
- Shoulders over hips
- Elbows relaxed at sides
- Forearms parallel to the floor or slightly upward
- Slight curve in lower back/lordosis
- Hip angle > 90 ideally 105-125!!!!!!!
- Feet flat on floor in tripod position
- Oral cavity centered at heart height
What should positioning be?
- When working on mandibular, position the occlusal plane of the mandible parallel to the floor
- When working on the maxillary, position the occlusal plane of the maxilla perpendicular to the floor
Know when it is appropriate to place a gingival bevel and when it is not
- If gingival floor is dentin/cementum, NO BEVEL
- Careful - enamel is thin here
- Bevel enamel to minimize microleakage and post-operative sensitivity
What are exit angles for composite?
composite should be >90 degrees to expose enamel rod ENDS for bonding
Obtuse angles are better for bonding
Buccal - 100-110 degrees
Lingual - 90 degrees or flared
What are exit angles for amalgam?
S curve on buccal
Improves resistance
Allows preparation to break contact while allowing the buccal wall to meet the tooth surface at a 90 DEGREE EXIT ANGLE
What is the purpose of the S curve?
Keeps narrowest part of preparation away from axiopulpal line angle
What is the function of a good matrix band?
- Has enough rigidity to resist too much deformation by packing forces or wedging, but is slightly burnishable and displaceable (in order to get good contact with the adjacent tooth) - Can’t be too stiff or thick
- Assists in establishing proper anatomical contour
Know the parts of the tofflemeir
What is the purpose of the wooden wedge?
Used to close the margin at the gingival of the box and prevent an overhang of amalgam
What should the marginal ridge look like?
- same height as the adjacent marginal ridge
- straight section, perpendicular to the long axis of the tooth, with a triangular inclined plane descending from the ridge crest into the pit
What is silver diamine fluoride?
- Silver in color and used to arrest caries.
- Used primarily on children since they will lose primary teeth
- Used on occlusal caries or maybe a location in the mouth that is hard to get to
- Turn a Very dark color, not aesthetically pleasing
What is fluorides role in managing caries?
Enamel resists acid more effectively
What are caries?
Infectious microbiologic disease of the teeth resulting in localized dissolution and destruction of calcified tissues
What are elements of caries?
Teeth - without teeth, bacteria have no habitat
Bacteria - streptococcus mutans
Substrate - any type of carbohydrate will support some strain of bacteria
Recipe for caries: tooth, biofilm (plaque), food source
What type of caries spreads the quickest?
Root caries due to cementum being softer than enamel
Describe infected caries?
Microorganisms are present
Soft-leathery
Describe affected caries
Dry, powdery
How can you see interproximal caries?
Clinically but more often use radiographs (bitewings)
PA Angulation = inaccurate
How long is the oral cavity affected after sugar consumption?
pH remains below 5.5 for 20-60 minutes after EACH sugar exposure
- pH at 5.5 is when demineralization of enamel begins to take place
- Dentin demineralizes at pH of 6.2
How do you detect caries?
use explorer to drag along surface to check for softness, use gentle pressure
Clinical visualization - shadowing
Radographs - only when large enough
How do you diagnose class II and III caries?
Bitwings
How do you diagnose caries near gingiva (Class V)?
Visually
What is the sound classification of caries?
No clinically detectable lesion
Normal in color, translucency and gloss
EO or RO (no radiolucency)
What is the initial classification system?
Earliest detectable lesion with mild demineralization
White or brown
Enamel has lost normal gloss
E1, E2, D1 (radiolucency may extend to the DEJ or outer 1/3 of dentin)
What is the moderate classification of caries?
Visible signs of enamel breakdown or signs the dentin is moderately demineralized
D2 (radiolucency extends into the middle 1/3 of dentin)
What is the advanced caries classification?
Enamel is fully cavitated and dentin is exposed
D3 (radiolucency extends into inner 1/3 of dentin)
What is the main pathogen for caries?
Streptococcus mutans!!
Streptococcus mitis
- Considered normal oral flora - presence can actually slow the growth of strep mutans colonies
Bacteroides melaninogenicus
- Obligate anaerobe
- Associated with periodontal disease
What are factors to consider when managing caries?
General health
Xerostomia
Fluoride exposure
What are ways to prevent caries?
Oral hygeine instructions
- plaque free surfaces dont decay
Dietary counseling
- ID sources
- reduce frequency and ingestion
- sealants
What are sesalants?
Thin resin coating placed on chewing surfaces of teeth
With or without enameloplasty
How to arrest caries?
- Fluoride
Enamel resists acids more effectively - Oral hygiene improvement
Reduces biofilms - Dietary changes
Reduces bacteria’s food source - Professional cleanings
May change recall intervals, more frequent assessment - Address xerostomia
What is an intermediate option to reduce caries?
Resin infiltration
- icon is used in the clinic
Silver diamine fluoride
Surgical management
What is occlusion?
The static relationship between the incising and masticating surfaces of the maxillary and mandibular teeth or tooth analogues
What is overjet?
Excessive horizontal overlap
What is overbite?
Excessive vertical overlap
What is excursive?
- Optimal occlusal relationships are canine guidance and anterior guidance
- If canine guidance and anterior guidance are not present, then occlusal interferences are present
- Occlusal interference: an unwanted or premature interocclusal contact
What is protrusive?
- Mandible moves forward
- Anterior teeth guide the movement
What is laterotrusive?
The canines on this side guide the movement (teeth with long roots and away from the fulcrum area)
What is mediotrusive?
No teeth should contact on this side (if they did, they would have off-axis loading
What matrix band would be useful for a badly broken down tooth needing restoration?
Automatrix system
- must be held in place by hand
- doesn’t work well when tooth defects go far apically
Copper band
-can be shaped by the fingers that approximates the outline of the tooth
What intstruments do you use to finish a composite restoration AFTER light curing?
The occlusal surface is shaped with a round or oval carbide finishing bor or similarly shaped finishing diamond
Or use the disc things
What intstruments do you use to finish a composite restoration BEFORE light curing?
Plastic instrument - to place and smooth composite on occlusal surface
hollenback carver - to carve anatomy, primarily used for amalgam
Optrasculpt - to develop anatomy in composite resin prior to light curing
When can you use resin infiltration?
Mild flurosis
White and brown spot lesions
- Following ortho treatment
Class II
Initial caries
When are indirect pulp caps used?
when a deep carious lesion occurs and there is no clinical or radiographic evidence or irreversible pulp damage (such as a history of spontaneous pain, heat sensitivity relieved by cold, or PA lesion)
What should a tooth look like for an indirect pulp cap?
- Be completely asymptomatic
- Show signs of reversible pulpitis
ex/ moderate cold sensitivity, with pain subsiding within about 15 seconds
Remember, caries is usually deeper than it appears to be on the radiograph
What is the objective of an indirect pulp cap?
AVOID A DIRECT PULP EXPOSURE
Describe the two appt approach of a pulp cap?
First appointment
- All caries are removed from all areas EXCEPT the deepest, nearest pulp
- Leave the last bit of infected dentin to avoid exposing pulp
- Cover remaining infected dentin with calcium hydroxide (Dycal or Life) then glass ionomer (Vitrbond)
- Place a temporary restoration - IRM
- It may be acceptable to leave some undermined enamel temporarily to help hold in the temporary restoration
Second appointment
- Allow 6-12 weeks to allow the body to form reparative dentin in the site of the near exposure
Desired result = dentin bridge formation
- At the end of the 12 weeks
Confirm that the patient is asymptomatic and that the tooth is vital
- Traditional approach
Remove the temporary restoration, the glass ionomer and the CaOH
CAREFULLY remove the remaining infected dentin (soft, leathery caries)
Leave the affected dentin (dry, powdery caries)
A #4 round bur on slow speed with a light shaving touch is the best choice for this function, better than a spoon excavator since the larger bur will put less force per unit area than the hand instrument would therefore making it less likely that one would break through the pulp
Place new liner of Dycal covered by vitebond. Remove all undermined enamel, modify the prep to properly retain the restoration, and restore with your selected permanent material
Describe the single appt approach of a pulp cap
- Remove infected (soft, leathery) dentin
- Remove affected dentin (dry, powdery caries) from any areas where a pulp exposure is not likely to occur
- DEJ must be completely caries free!
- Leave the affected dentin ONLY in the deepest area where the possibility of a direct pulp exposure is a concern. You want to remove ALL affected dentin if at all possible
- To avoid pulp exposure, it may be permissible to leave a small amount of affected dentin in deep areas
Place CaOH (dycal or Life) over the deepest area close to the pulp
Place glass ionomer (vitebond) over the CaOH
There is fluoride release from the vitrebond allowing possibility of remineralization of the affected dentin as long as restoration is well-sealed - Remove all undermined enamel and place the permanent restoration
If time does not permit placing the permanent restoration (if, for instance, you are trying to do temporary, caries control restorations in several teeth at the same appointment, place a temporary restoration
Schedule next appointment to complete definitive restoration - do not remove vitebond or dycal
If crown is indicated, RCT is recommended prior to placement of the crown
When are direct pulp caps used?
Used when a small pulpal exposure occurs during cavity preparation
What material is used in a direct pulp cap?
A thin layer of calcium hydroxide is placed over the exposed pulp
A layer of glass ionomer is placed over the CaOH
Stimulate the pulp to form secondary odontoblasts, which can produce a dentin bridge across the exposure site
When are direct pulp caps most successful?
when the exposure is mechanical rather than carious
- When pt is young, in exposure sites less than 0.5 mm
- If bleeding at the site is easily controlled and there is no pus or serious exudate
- If area has not been contaminated by saliva
- If there has been little or no mechanical damage to the pulp tissue
When is it not appropriate to place a pulp cap?
- spontaneous pain!!!!!!
- Pulp exposure - indirect pulp cap is no longer an option - direct pulp cap may be an option
- If the tooth will require a crown, DO NOT RELY DIRECTLY ON PULP CAP
What is reversible pulpitis?
Pulpal sensitivity due to caries or following cavity preparation and restoraiton
What are symptoms of reversible pulpitis?
Twinge of pain due to sugar, cold, or acid from caries first contacting dentin
Pain lasts a few seconds
How to test for reversible pulpitis?
As long as an irritant, such as touching an ice stick to the tooth causes pain that lingers no more than 10-15 seconds after removal, its called reversible pulpitis and can be treated with a restoration
What is irreversible pulpitis?
When pain is spontaneous, or elicited by an irritant linger more than 15 seconds, infection of the pulp often has occurred and resolution by operative dentistry treatment is usually no possible; root canal therapy is advised
What is pulpal necrosis?
When this irreversible pulpitis is untreated
What are symptoms of pulpal necrosis?
- spontaneous, continuous, throbbing pain elicited by heat than can be relieved by cold and then later no response to any stimulus
- as inflammation and infection move beyond the root apex, the tooth may become sensitive to percussion
What is therapy for pulpal necrosis?
Root canal therapy
