Bases, Liners, and Ideal Class II Preps Flashcards
What are the four criteria that are established during the initial stage of cavity design?
- outline form and initial depth
- resistance form
- retention form
- convenience form
What is done during the final stage of cavity prep design?
- removal of remaining pits, fissure, infected dentin, and old restorative material
- protecting the pulp
- secondary retention/resistance form
- finishing enamel walls to remove unsupported rods
- cleaning, inspecting, conditioning
What is the initial depth of a cavity design?
0.2-0.8 mm pulpally from the DEJ (into dentin)….usually 0.5mm
_______ is the shape and placement of cavity walls that best enables both the restoration and the tooth to withstand masticatory forces delivered along the long axis of the tooth.
Resistance Form
________ is the shape or form of the prepared cavity that resists displacement or removal of the restoration from tipping or lifting forces.
Retention Form
_________ is the shape or form of the cavity that provides for adequate observation, accessibility, and ease of operation.
Convenience Form
What are the four functions of the dentin-pulp complex?
- Formative (primary/secondary dentin)
- Defensive (reparative dentin via odontoblasts)
- Nutritive (supply of vital cells)
- Sensory (protective/pain response)
What is the single sensory response of the dentin-pulp complex?
PAIN
The Hydrodynamic Theory suggests that pain responses are due to ____________.
micro-movements of tubule fluids
What type of changes could cause movement of tubule fluids?
- osmolarity changes
- thermal changes
- desiccation
- pressure changes
- high-speed cutting
What are the three possible diagnoses of the pulp status?
- Normal/Healthy
- Pulpitis
- Necrotic
Reversible pulpitis shows a sensitivity to ______.
Irreversible pulpitis shows a sensitivity to _______.
Reversible: COLD
Irreversible: HOT
Tooth pain can be evaluated based on these five characteristics:
- Location
- Intensity (sharp or dull; pulp pain is sharp)
- Cause of onset (hot, cold, sweet stimulus or spontan)
- Duration (lingers or short)
- Pain during occlusion
Name three clinical methods for testing pulp status.
- Cold Test /Hot Test
- Electric Pulp Test (EPT)
- Percussion Test
Why do we need bases and liners?
to protect the pulp and minimize post-op sensitivity
many materials do not act kindly to the pulp, ex. acid
How do bases and liners minimize post-op sensitivity or protect the pulp?
- thermal barrier
- chemical barrier
- electrical barrier
- mechanical barrier
- control of inflammation
- control of fluid movement
Why are calcium hydroxide liners often placed into very deep preparations?
calcium hydroxide stimulates reparative dentin
What is a liner?
relatively thin layers of material used to:
- provide a barrier to protect dentin from residual reactant diffusion or from oral fluids
- electrically insulate
- thermally protect
- provide pulpal treatment (some formulas)
Types of Liners include: \_\_\_\_\_\_\_ Liners (copal varnish and adhesives), \_\_\_\_\_\_\_ Liners (CaOH/Dycal), \_\_\_\_\_\_\_\_ Liners (GI/KetacCem), \_\_\_\_\_ Liners (ZOE), and \_\_\_\_\_\_\_ (Optibond Solo/Gluma).
Solution Suspension Cement Eugenol Dentin Bonding Systems/Sealers
True or False: If the remaining dentin thickness is greater than 2.0mm, two layers of copal varnish can be used under amalgam.
True
List the three common liners used under amalgam (from thinnest to thickest)
Solution Liners (2-5 micrometers) Suspension Liners (20-25 micrometers) Cement Liners (200-1000 micrometers)
One layer of copal varnish will provide a ____% seal, Two layers of copal varnish will provide a ____% seal.
55%
85%
True or False: CaOH, RMGI, and ZOE are all types of liners.
True
What are bases?
bases are used to provide thermal protection for the pulp and to supplement mechanical support for the restoration
-they distribute local stresses across the underlying dentin surface
How thick are typical cement bases?
1 - 2 mm
Dental cements that are used as a base are mixed at a _____ powder to liquid ratio to increase the final compressive strength.
higher
Bases provide _____ protection for the pulp and _____support for restorations.
thermal
mechanical
If the ideal prep design does not remove all carious tissue, what should you do?
-extend access opening laterally until the DEJ is no longer carious, remove any carious dentin
The RDT (remaining dentin thickness) after preparing a moderately carious lesion is between 0.5 and 2.0 mm thick. A base and liner are placed for amalgam and composite restorations. How do they differ?
Amalgam:
Base replaces the missing dentin
-GI and ZnPO4 base
-Copal Varnish or Adhesive liner
Composite:
Minimal Base theory
-GI/ZOE = base
-Copal Varnish or Adhesive = liner
Bases and Liners often differ only by their _______.
consistency (Powder to liquid ratio)
Why is zinc phosphate more difficult to use as a base?
a particular mixing technique must be used
True or False: RMGI can act as both a liner and a base.
True
BOARDS: When mixing CaOH for use as a liner, what is the ratio of powder to liquid?
mix equal portions of each
BOARDS: When mixing ZOE for use as a liner, the paste-liquid system uses ____ drops of liquid per scoop of powder.
2 to 3
True or False: Bases replace the dentin and enamel.
False, bases replace dentin only…do not allow it to coat the enamel margins
Why have GI materials replaced ZnPO4?
Advantages of GI:
- adheres to the tooth structure (dynamic ion process)
- Fluoride release
- proven clinical record of retention
- dimensionally stable
- biocompatible (much kinder to the pulp)
True or False: Glass Ionomer materials increase in strength over the course of 24-72 hours as Aluminum ions replace Calcium
True
KetacCem is a common type of _____.
RMGI
Caries are considered “extensive” when they are how close to the pulp?
when there is less than 0.5mm remaining dentin thickness
When pulp capping, how does the type differ based on pulp exposure or near exposure?
Near Exposure = less than 0.5mm RDT
= INDIRECT pulp cap
Pulp Exposure = DIRECT pulp cap
The ______ pulp cap is used as a defense by initiating reparative dentin.
indirect
_____ days after the placement of an indirect pulp cap, the cells will differentiate.
15
After ___ days there will be microscopic evidence of reparative dentin and after _____ days there will be radiographic evidence.
30 days = microscopic
100 days = radiographic
How do the indirect and direct pulp cap differ?
They both have the 15 day differentiation, 30 day microscopic dentin, 100 day radiographic dentin
-however, the direct pulp cap is less effective and the results are not as good
The CaOH Liner combines a CaOH paste with a ______ paste, which causes a _______ reaction.
polyphenol
acid-base
How are the polyphenol groups in CaOH linked?
crosslinked by calcium ions
CaOH Liner has _____ solubility.
HIGH
10-30% volume is lost in 10 years
What is the brand name of CaOH liner?
Dycal
When ionized in low concentration, CaOH stimulates ______.
odontoblast formation/reparative dentin
What are five factors that contribute to prognosis related to pulp capping?
- Size of exposure (smaller exposure = better results)
- Tooth symptoms
- Hemorrhage control
- Field Cleanliness (rubber dam)
- Sealing the access
When is a “sedative restoration” material used? Give two materials that fall into this category.
for questionable pulp status or
emergency treatment with limited time
- Reinforced ZOE B&T (base and temporary)
- IRM (intermediate restorative material)
Oil of clove (in ZOE) acts to ______.
dull pain (obtundent)
Reinforced ZOE cannot be used under ______.
composite
Why can’t ZOE be used under composite?
inhibits polymerization
causes poor bond strength and microleakage
For deep caries (with less than 0.5mm RDT) that is asymptomatic, what should be placed under the amalgam restoration?
- CaOH (or RMGI)
- Base
- Copal Varnish
- amalgam
For deep caries (less than 0.5mm RDT or exposure) that is questionable , what should be placed in the cavity?
- CaOH
2. Sedative Fill (ZOE)
Compare liner/base use prior to amalgam preparations:
- Shallow tooth prep
- moderate-depth tooth prep
- very deep tooth prep
- Shallow: varnish or sealer applied to walls
- Moderate: varnish or sealer on walls, liner of ZOE or CaOH for thermal protection
- Deep: varnish or sealer on walls, CaOH liner in deepest portion, then GI base
How much RDT would indicate the use of medicament prior to placement of amalgam or composite?
less than 0.5mm RDT
you would then need a liner on top, then a sealer
How much RDT would indicate the use of a liner prior to placement of amalgam or composite?
less than 2mm RDT indicates the use of liners
you would then need a sealer on top
Always make sure that there is no basing material on ________.
margins!
base is only to be placed in the deeper part of the prep, away from margins