Operative Flashcards
Hydroxyapatite (HA)
Ca10(PO4)6(OH)2
* Hexagonal
* White Power
* Low Bioresorption rate: Doesn’t mimic inorganic portion of teeth
Carbonate-Substituted Hydroxyapatite (CHA)
Main component of enamel & dentin
Carbonate increases sollubility of HA=easier to decay
* mostly found at DEJ, (Fluoroapatite on surface of tooth mostly)
* enamel rod=Keyhole pattern
* Head
* Tail=more organic, less mineral content=more susceptible to decay
Describe the structure/composition of enamel
More FA near the outside
More CHA near the DEJ(Deeper enamel)
What are the 3 ways that Fl can prevent decay?
- Remineralization of tooth structure
- Decreasing Enamel Solubility (lower critical pH)
- Interfering w/metabolic activity of cariogenic bacteria
What is the critical pH?
equilibrium b/w demineralization & remineralization
* the lower the critical pH the more resistant to demineralization
What is the critical pH of enamel (FA) vs Enamel (CHA) vs Dentin/Cementum
Enamel (FA)=4.5
Enamel (CHA)= 5.5
Dentin/Cementum: 6.2-6.7
What is caries?
Multifctorial transmissible infectious dynamic oral disease
* result from interaction b/w: Biofilm, Diet, Host Factors, & Time
- Modeled by: Modified Keyes-Jordan Diagram-added time
What is the shape of pit and fissure lesions?
Inverted V-Shape
What is the shape of Smooth Surface lesions?
V-Shaped (Double arrow head)
* spreads wide again at DEJ
What is the shape of root surface lesions?
V-shaped
* Rapid progression bc no enamel
Infected vs Affected Dentin
Infected Dentin:
* Superficial layer
* Wet, soft, Mushy
* Necrotic
* bacteria present=active infection
Affected Dentin:
* deeper
* dry
* leathery
* demineralized but NO bacteria
Progress of Lesions
Intact surface
* enamel
* required for remineralization
Cavitation
* irreversible
* requires restorative tx
Takes 1-2 years to form an enamel cavitation (Cavity)
* white spot to cavitation
What are the steps in cavity formation?
- Enamel Demineralization
- Dentin Demineralization
- Enamel Cavitation (irreversible)
- Dentin Cavitation
Incipient Lesion
Aka Reversible
* smooth surface
* appears white when dried and disappears when wet (NOT Hypocalcification)
Cavitated Lesion
- irreversible
- broken enamel surface (not intact)
- advanced into dentin
Simple carious lesion
covers 1 surface of tooth
* O
Compound Carious Lesion
Covers 2 surfaces of a tooth
* MO, DO
Complex Carious Lesion
Covers 3+ surfaces
* MOD, MODFL
Primary caries
Original Lesion
Secondary caries
- aka recurrent caries
- occurs at jxn of tooth and restoration
- indicates microleakage
Residual Caries
- caries that are still in a completed tooth prep
Acute Caries
Aka Rampant Caries
* rapid tooth damage
* light-colored
* soft
* infectious
Chronic Caries
Aka Slow Caries
* Demineralized but almost remineralized
* discolored
* fairly hard
Arrested Caries
- Brown/black appearance
- hard
- if exposed to Fl=Caries resistant (dentin has sclerotic dentin)
What bacteria can cause cavities? (Cariogenic Bacteria)
- Streptococcus mutans
- Lactobacillus
- Actinomyces
Streptoccocus mutans
ENAMEL CARIES
- Glucosyltransferase (GTF):
- Acidogenic
- Acidureic
bacteriocin
Lactobaccilus
Dentin caries
Actinomyces
Root Caries
Saliva
Main Natural protective agent
Contains:
* Glycoproteins:
* Lysozyme
* Lactoferrin: Inactivate iron
* Lactoperoxidase: inactive enzymes (-ases)
* sIgA: Salivary antibody against bacteria
Clinical Exam for caries consists of:
- Visual Changes in tooth surface texture or color
- Tactile sensation w/explorer
- Radiographs
- Transillumination
Clinical Exam: Visual changes in tooth surface texture or color
always in dry, well-lit field
Incipient caries:
* partially or totally disappear from vision by wetting
* hypocalcification/decalcification does not
Clinical Exam: Tactile sensation w/explorer
- Place cotton rolls in vestibules
- remove excess saliva w/suction
- be careful to not cavitate incipient lesions
Clinical Exam: Radiographs
White Spot: Hardly visible
Enamel Cavitation: Evident
Dentinal Lesion: Clearly evident
Lesions are smaller on radiograph than clinically
* requires 30-40% mineral loss to be detected by radiographs
Clinical Exam: Transillumination
Anterior Teeth: Shadow=interproximal caries
craze lines: whole tooth lights up
Fracture: Bocks light from shining through
Amalgam Exam consists of: (What to look for)
Do NOT Replace:
Bluish Hue:
* due to corrosion
* not defective
Needs to be redone if:
Voids
Fracture lines
Proximal & Margin Overhang
Marginal Gap or ditching >0.5 mm=caries prone
Erosion
chemical loss of tooth structure w/o bacteria
*cause=Acidic foods/drinks or gastric acid
* NOT caused by bacteria
* Manifests as “Cupping”
Abrasion
Loss of tooth structure by mechanical wear
* ex: aggressive tooth brushing
* most common=porcelain or ceramic crowns against teeth
Attrition
Loss of tooth structure due to:
* Occlusal wear from functional contacts w/opposing teeth
* bruxism
Abfraction
Loss of tooth structure in cervical 1/3
* due to tooth flexure
* multifactorial: Tooth flexure, toothpaste, abrasion, chemical erosion
Hypersensitivity:
- due to exposed dentin tubules in root surface
Hydrodynamic Theory
Root Hypersensitivity
Pain is due to dentin fluid movement that stimulates mechanoreceptors near predentin
Causes of fluid shift:
* Temp change
* air-drying
* osmotic pressure
Treatment Plan Sequencing
What the pt needs most is what needs to be done 1st
- Urgent Phase: Acute infection, pain, swelling
- Control phase: Caries, oral hygiene
- Re-evaluation phase
- Definitive phase: ortho, prosth, surgery (establish optimal esthetics)
- Maintenance phase
Criteria for restoring teeth/Restorations
High Caries Risk
* 2+ active caries
* large number of restorations
* Poor dietary habits
* low salivary flow
* poor OH
* low FL exposure
* Unusual tooth morphology
Lesion extends to DEJ
Cavitation
Define Preventative Dentistry
Encourage Remineralization
* incipient smooth-surface lesions
* Fl use
* Decrease caries risk factors
Sealants:
* Deep pits and fissues
What is the critical pH of enamel?
5.5
What are the steps required in a tooth prep?
- Outline Form
- Primary Resistance Form
- Primary Retention Form
- Convenience Form
- Remove caries
- Pulp Protection
- Secondary Retention & Resistance Forms
- Finishing External Walls
Outline Form
external outline of prep
* along cavosurface margin
* Defined by extent of the carious lesion
* remove all unsupported enamel
Extend to sound tooth structure
* initial depth of 0.2 mm into dentin
* gingival floor: 0.5 mm clearance ALWAYS
* F & L Proximal walls: 0.5 mm clearance EXCEPT if you would remove sound tooth to break contact
Friable Enamel
Demineralized
* bonding is not as effective
Unsupported Enamel
Undermined & Weaker
* high possibility for fracture
Define Resistance Form
Shape and placement of adjacent walls
* Tooth and restoration withstand masticatory forces
* Prevent fracture
Define Retention Form
prevent displacement of restorative material
* Convergent walls: Prevent occlusal displacement
Dove tail: Prevent proximal displacement
Composite=rely on bonding
Convenience Form
Improve access and visibility as needed
Caries Removal
- Remove ALL infected Dentin
Pulp Protection
If you are close to the pulp=Indirect pulp cap (Base)
< 1mm exposure & asymptomatic –> Direct Pulp Cap (Liner + Base)
> 1mm exposure & symptomatic–> RCT
GLUMA
Sealer/Desensitizer
Used for sensitivity: Occludes dentin tubules
* need 2+ mm of Dentin to pulp
GLUMA consists of:
Consists of:
* 5% Glutaraldehyde
* 35% HEMA
* Water
Liner
Used for direct pulp cap or near pulp exposure
* Barrier=Protect dentin from residual reactants of restoration & oral fluid
Electrical Insulation
Thermal Protection
Form Tertiary Dentin
Ex: CaOH or RMGI
Base
Used for metal restorations or w/a liner
* prevents liner from being washed out
* Thermal protection (under amalgam or gold)
Distributes local stresses across
RMGI or GI Cement
* Ex: Vitrebond
What is indicated for Amalgam and RDT (Remaining Dentin Thickness)
> /= 2mm: Sealer
0.5-2.0: Base + sealer
< 0.5 mm: Liner + Base + Sealer
What is indicated for Composite and RDT (Remaining Dentin Thickness)
> /= 0.5 mm: Bond
< 0.5 mm: Liner + base + bond
What is indicated for Gold or Ceramic and RDT (Remaining Dentin Thickness)
> /= 2.0 mm: Cement
0.5-2.0 mm: Cement (2mm thick)
<0.5 mm: liner, base, cement
Secondary Resistance & Retention Form
Retentive Grooves
Beveled Enamel Margins
Slots
Pins
Amalgam Preparation
Carbide Burs: creates smoothest walls
Retention:
* occlusal convergance
* Grooves, slots, pins (secondary) if needed
Resistance for Tooth:
* 90 degree cavosurface margin
* Maintain cusps and marginal ridges
* Remove unsupported enamel
* Flat floors
* Rounded internal line angles
* Pins
Resistance for Amalgam:
* 90 degree amalgam margin
* 1.5-2.0 mm depth for adequate thickness of amalgam
Composite Preparation:
Use Coarse diamond –>rough walls=micromechanical retention
Same as amalgam except NO need for:
* retentive features
* occlusal convergence
* can be shallower: 1-1.5 mm
Gold Onlay Preparation
Collar
* beveled shoulder around capped cusp for bracing
Skirt
* Feather edged margin around capped cusp
Provides Secondary R&R FORM
Slots
at least 1 mm Deep & Long
* 0.5 mm inside DEJ
Pins
Self threaded pin=most common
* Missing vertical wall