Unit 2 Exam Topics Flashcards
1
Q
Why is it a good idea to provide the patient with a temporary restoration?
A
Temporization rationale:
1) Inter-arch and intra-arch stabilization
2) Protect the remaining tooth structure: vital teeth remain sensitive, non-vital teeth can crack
3) Patient comfort and cosmetics
2
Q
Esthetic inlay/onlay provisional restoration materials include…
A
- polymethylmethacrylate
- bis-acrylic
- composite resin (total etch and dentin bonding agent NOT indicated)
- low elastic temporary material
3
Q
Examples of polymethylmethacrylate (PMMA)
A
- Trim acrylic
- Jet acrylic
- Alike acylic
- Vita acrylic
Temporary cement indicated
4
Q
Examples of bis-acrylic
A
- Luxatemp
- Protemp Plus
- SmarTemp
Temporary cement indicated
5
Q
Examples of low elastic temporary material
A
• fermit-N
No cementation required
6
Q
Treatment options for cusp fracture, when tooth is vital and there is no pulpal involvement.
A
- Direct restoration
- Indirect restoration (2 visits)
- One-visit indirect restoration
7
Q
Type of direct restoration…
A
Complex amalgam
8
Q
Type of indirect restoration (2 visits)…
A
- Porecelain onlay
- Composite onlay
- Full gold crown
- Porcelain fused to metal crown
- All ceramic crown
9
Q
Types of one-visit indirect restoration…
A
- CAD/CAM
* Ceramic onlay or crown
10
Q
Considerations for which temporary material to use…
A
- Occlusion (what is the opposing tooth like?)
- Cuspal placement (is there a tooth distal and mesial?)
- Longevity (how long will the patient need to wear this temp?)
11
Q
Quick matrix for the acrylic temporary technique can be…
A
- Clear stent
- Putty matrix
- Quadrant alginate
12
Q
Steps in the acrylic temporary technique…
A
• Make a quick matrix (of unprepared teeth)
• Lubricate the prepared tooth
- If a base was applied the acrylic will adhere
• Mix and press the acrylic material against the prep
- Just enough (DO NOT OVER FILL)
- Tease it off the prep before the final set
- Re-seat it for the final set
• Finish, check occlusion, and polish
13
Q
Acrylic temporary technique tips
A
- Wait until the material is starting to opaque to press
- Remove excess material while it is still unset
- Re-seat it for the final set
- Use composite for minor repairs, it will bond with the acrylic (flowable is very useful and fast)
- Check contacts and occlusion before final polish
- Never use etch and bonding
- Never use materials containing eugenol
- Cement with durelon (polycarboxylate cement) if fit is too loose
14
Q
Bis-acrylic temporization technique
A
1) Lubricate the prepared tooth
a. If a base was applied the acrylic will adhere
2) Dispence the material in the matrix and press the acrylic material against the prep
a. Just enough - DO NOT OVER FILL
b. Wait for the final set before removal
3) Finish, check occlusion, and polish
15
Q
Temporization techniques if patient presents as an emergency and no prior models are available…
A
- Option A: Use ortho wax to make a quick fill of the defect in the patient’s mouth, take a quadrant alginate to serve as the matrix
- Option B: Make a ball of acrylic, in a putty-like state, load the preparation, have the patient bite to imprint the opposing dentition with excursions and follow through with teasing it off before final set, re-seating for final set, shape, finish, and polish.
16
Q
Diagnosis: Tooth #18 has a wide mesio-occlusal preparation with a failed amalgam restoration. Tooth is vital, no pulpal involvement, patient requests a cosmetic restoration.
Treatment options?
A
• Inlay temporization
• Treatment options:
- Direct restoration (1 visit) –> large composite [poor prognosis]
- Indirect restoration (2 visits) –> porcelain inlay, composite inlay
- Indirect restoration (1 visit) –> CAD/CAM, ceramic inlay
17
Q
Composite resin as a temporary…
A
- Don’t throw away expired composite
- DO NOT etch and bond
- Just pack, shape, light cure, finish and polish
- Try to remove it! Drill it out at visit 2.
18
Q
What’s Fermit-N?
A
- Composite resin, single-component, light-cure, for temporary restoration and temporary onlays.
- Stays flexible
- Removal –> can be peeled out
19
Q
Mack II-Blu Mouse technique…
A
- Take alginate of preparation
- A retrievable die is made to fabricate the temporary directly
- Retrieve a die to work on chairside
- Fir the temporary intra-orally and make any corrections if necessary
- Insert with eugenol free temporary cement
20
Q
What’s an inlay?
A
• An inlay fits within the grooves that are within the cusps of your teeth.
21
Q
What’s an onlay?
A
- An onlay, the larger of the two, fits within the grooves but wraps up and over the cusps covering more of the tooth’s surface.
- An onlay is used when the damage is more extensive and the restoration covers the entire chewing surface including one or more tooth cusps.
22
Q
Indications for esthetic inlay/onlay
A
- Patient requests esthetic restoration
- All margins on enamel
- Larger restorations
- Cuspal coverage
- Short occluso-gingival dimension (2mm clearance)
23
Q
Containdictions for esthtetic inlay/onlays…
A
• Severe parafunction:
- Clenching
- Bruxism
- Chewing habits
• Subgingival preparations (isolation)
• Preparations with bevels
24
Q
Wear properties of resin composite vs porcelain
A
- Porcelain is more abrasive to the opposing dentition
* Resin composite wear of opposing dentition is similar to gold (kinder to opposing tooth)
25
Composite longevity
Studies are needed to confirm the longevity of indirect resin composite.
26
Porcelain longevity
* Traditional feldspathic porcelain high failure rates
* Pressed ceramics are showing some promise
* More research is needed
27
Indirect vs. direct resin composite advantages...
* Control over interpoximal contour and margins
* Less polymerization shrinkage
* Greater strength + hardness
* Less post-op sensitivity
* Operator friendly
* Easily add contact
28
Indirect vs direct resin composite disadvantages...
* Chair-time (# of visits)
| * Lab expense
29
Advantages of porcelain inlay/onlay vs composite inlay/onlay
* Strength and wear resistance
| * Long-term occlusal stability
30
Disadvantages of porcelain inlay/onlay vs composite inlay/onlay
* Technique sensitive
* Prone to fracture at try-in or final luting
* Difficult to adjust and fit b/c brittle
* Additional firing time for adjustments/add-ons
* Wears opposing tooth
31
Evidence based treatment options: class II porcelain inlays
Class II porcelain inlays had a higher breakage rate than resin composite inlays
32
Evidence based treatment options: two and three surface resin composite inlays
Two and three surface resin composite inlays are best suited for preparations of moderate width in premolar
33
Evidence based treatment options: porcelain onlay
Porcelain onlay is preferred for the coverage of a missing cusp on a posterior tooth
34
Esthetic onlay preparation considerations
* Divergent towards the occlusal (inner walls)
* Relatively non-retentitive
* Rounded proximal boxes and internal angles
* Grooves should not be used
* Minimum 2mm occlusal reduction
* No bevels - 90 degree butt joint margins
* Esthetic areas on the facial - long chamfer
35
Porcelain onlay preparation, stone die, and clinical view...
* Retention by bonding to the enamel and dentin
| * Walls and floors of the preparation should be smooth
36
Esthetic inlay preparation considerations
* All margins should be on enamel
* Longitudinal walls must diverge as the preparation approaches the occlusal surface
* Retention provided by bonding to the enamel and dentin
* Walls and floors of the preparation should be smooth
* Internal line angles should be rounded
* Minimum 2mm preparation depth
* No bevels
* A butt joint is recommended
37
When should liners and bases be placed when doing inlays/onlays?
* Liners should only be placed to protect the pulp
| * Bases should only be used to block out undercuts
38
Types of composite inlay/onlays
* Direct
* Direct/indirect
* Indirect
39
What are direct resin composite inlay?
* Directly formed in tooth and teased out
* Postcured in office
* Luted same visit
40
Direct/indirect resin composite inlay preparation
* Impression of prepared tooth is poured with a silicone materla, die is retreived at chairside within 5 minutes
* Restoration fabricated on the die
* Postcured
* Luted same visit
41
What are indirect resin composite inlay/onlays?
* Fabricated by commercial dental lab
| * Shade selection, finish, and polish are superior to direct technique
42
Indirect resin composite fabrication
Secondary polymerization:
| • Postcure performed with a combination of light, heat, and pressure
43
Types of porcelain inlay/onlays
* Feldspathic porcelain fabricated on a refractory model
* Pressed ceramic
* CAD/CAM
44
Porcelain inlay/onlay fabrication - refractory method
* The refractory method uses a die made from a high heat "refractory material"
* Porcelain baked on refractory die, recovered and fit to a master die
* Technique sensitive and mastery of restoration takes years to achieve
45
Porcelain inlay/onlay fabrication - pressed ceramic technique
* Wax-up, invested, burn-out, pressed ceramic material heated and pressed into the lost-wax pattern space
* Retrieved and finished as feldspathic porcelain
46
Esthetic inlay/onlay adhesive cementation requirements...
* Tooth cleaned free from plaque, stain, calculus, or any debris
* Rubber dam isolation is recommended
* Use dentin bonding system
* Luting with a dual cure resin is recommended
47
Esthetic inlay and onlays adhesive cementation for composite..
* Intaglio air-abraded with 50-um aluminum oxide (avoid margins)
* Silane (coupling agent) is applied as the wetting agent.
48
Esthetic inlay and onlays adhesive cementation for porcelain...
* Porcelain must be etched prior to final luting (usually done by the lab with hydrofluoric acid)
* Silane is applied to porcelain to enhance wetting of the resin adhesive
49
Esthetic inlay and onlays adhesive cementation procedure...
* Etch enamel 30 seconds + dentin for 15 seconds
* Rinse and visually inspect enamel etch
* Re-moisten dentin
* Apply dual cure prime and bond system
* Dual cure bonding agent is applied to the tooth and the intaglio of the restoration
* Dual cure luting resin is mixed and placed into the preparation and the intaglio of the restoration and seated
* Adjust occlusion, finish, and polish
50
Maintenance of esthetic inlays and onlays...
* Avoid ultrasonic scalers
* Avoid air-abrasive polishers
* Careful with hand scalers
* Avoid APF or Stannous fluorides
* Use neutral sodium fluoride
* Use aluminum oxide polishing pasts or diamond polishing pastes
* Avoid high staining foods
* Avoid ice chewing
* For parafunction - use a protective appliance
51
Failures of onlays/inlays include...
* Bulk fracture
| * Marginal breakdown
52
Indications for direct posterior composite restorations...
* Acceptable oral hygiene
* Centric occlusal stops on tooth structure
* Proper isolation
* Esthetics are a prime consideration
* Cavosurface margins are in enamel
* Faciolingual width limited to 1/3 or less the interocclusal distance
53
Centric stops will remain where on direct posterior composite restorations...
Centric stops will remain on sound tooth structure
54
Contraindictions for direct posterior composite restoration...
* Poor oral hygiene
* Allergy to resin-based material
* Excessive wear from grinding
* Improper isolation
* Faciolingual width > 1/3 the intercuspal distance
* Deep class II proximal boxes which place the gingival cavosurface margin beyond the enamel
55
Advantages of a direct posterior esthetic restoration
1) Esthetics
- Visible-light-cured (VLC) resin composite used today are more color stable than previously used auto-cured composites
2) Adhesion to tooth structure
- Bonding between the resin composite and tooth structure potentially seals the margins of the restoration
- Has been shown to protect against the propagation of cracks
3) Low thermal conductivity
4) Eliminate galvanic currents
5) Radiopacity - ADA requires the material to have an approximate radiopacity to dentin; older composite restorations were not radiopaque
6) Conservative - the current design recommended by evidence based practice is to limit tooth removal to remove carious tooth and fragile enamel
7) Alternative to amalgam in very small restorations (cannot be placed in high stress areas)
- Although there is no correlation between amalgam and health problems, patients frequently request a mercury free restoration
- DEP requirements for separation and disposal place an added burden on dental practice
- Unesthetic appearance in a cosmetic world
56
Disadvantages of a direct posterior esthetic restoration
1) Polymerization shrinkage --> gap formation:
• Current newer materials have shown shrinkage toward the walls of the cavity preparation to which the composite is bonded most strongly
2) Secondary caries lesions
• Significant cause of failure likely associated with gap formation (especially at gingival margins)
• Studies have shown that Streptococcus Mutans in plaque are higher surrounding composites than amalgam or glass ionomer
• Organic acids of plaque have a negative effect on the bis-GMA polymers increasing wear and stain
3) Postoperative sensitivity
• Likely as a result of gap formation
• Cuspal deformation from contraction forces of polymerization shrinkage may cause hydraulic pressure in the tubular fluid
• Outflow of fluid from pulp = pain
4) Decreased wear resistance
• Abrasion +/ or attrition
- Never use a microfilled composite for the posterior
- The more posterior a tooth, the more wear it will exhibit
- Proximal surfaces are subject to abrasion
- When used selectively for small occlusal restorations, newer composites have shown acceptable wear
5) Low fracture resistance compared to metal restorations
6) Bulk fracture from high degree of elastic deformation
7) Water sorption - hydrolytic breakdown through the resin
8) Variable degree of conversion
• Lighter shades cure more easily
• Increased curing light exposure time; increased cure
• Holding the light closer to the composite surface increases cure
• Cleanliness of end of light rod is important to maximize the light intensityy
9) Inconsistent dentin adhesion (marginal leakage)
10) Technique sensitivity - little room for error
57
What causes abrasion wear?
Loss of tooth structure by mechanical forces from a foreign element
58
What causes attrition wear?
Loss of tooth structure by mechanical forces from opposing tooth
59
Before placing the composite, the following items must be satisfied...
1) Preparation must be thoroughly cleaned before placing the restoration
2) The matrix must seal the gingival cavosurface perfectly
3) The restoration must be properly finished and polished (after placement of composite)
60
Applications for (posterior) direct resin composite...
* Sealants
* Preventive resin restorations "PRR"
* Class I cavity restoration
* Class II cavity restoration
61
Conservative tooth preparation for direct posterior composite...
* No need to penetrate dentin if caries lesion does not
* Narrower outline form
* Rounded internal line angles
* NO EXTENSION FOR PREVENTION (Sealant is used for remaining fissures)
* Occlusal margins are NOT beveled
62
Preoperative steps for direct posterior composite...
* Check shade
* Use articulating paper to determine occlusal stops
* Determine isolation technique - without a rubber dam, class II's marginal leakage increased 4-6 weeks after placement
63
Sectional matrices can be used for...
direct posterior composite restorations
64
Class II pre-wedging for direct posterior composite restoration accomplishes...
* Helps to secure adequate space for the matrix
| * Protects adjacent tooth surfaces during preparation
65
Purpose of the matrix in direct posterior composite restoration...
Metal matrix provides superior contact than clear plastic matrix
66
Class II direct (posterior) resin restoration procedure...
* Clean and dry surface with 3 way syringe
* Acid etch 15 seconds after matrix is placed to protect the adjacent tooth surface
* Rinse and dry lightly to not dessicate the dentin. If dentin is dry it needs to be rewet before the adhesive
* Apply the bonding agent (glossy appearance), gently disperse to a thin layer and set with the light for 20 seconds
67
Class II - the first increment (direct posterior composite)
* 1 mm increment in box against gingival floor
| * Remember to re-light cure after the matrix is removed
68
Subsequent layering of direct resin composite for class II is done...
• Incrementally:
| - 2 mm increments are layered obliquely
69
Class II - final increment for direct resin composite...
* Control helps to minimize the amount of finishing
* Finishing burs are used to contour the restoration
* Pre-polish with abrasive points, cups, etc...
70
When is occlusion adjusted in class II posterior composite restoration?
Occlusion is adjusted once rubber dam is removed and polish is finalized with diamond paste
71
Possible techniques for direct composite class IV include..
* Free hand
* Putty matrix
* Clear stent
* Strip crown
72
True or false: prime and bond NT is a fifth generation bonding agent
True
73
What is prime and bond NT?
• A self priming, light cured bonding agent.
• The components are:
- Nanofiller (amorphous silicone dioxide) 7nm in diameter
- PENTA, dipentaerythritol penta acrylate monophosphate
- di and tri-methacrylate
- acetone solvent
74
True or false: the bond strength for prime and bond NT is greatest on dentin.
• False, the strongest bonds are on enamel:
- Enamel = 28 MPa
- Dentin = 22 MPa
75
True or false: the total etch technique involves placement of 35-38% phosphoric acid on enamel and dentin.
True
76
By whom and when was the acid-etch technique invented?
• Buonocore invented the acid-etch technique in 1955.
77
_____ developed enamel bonding agents based on bis-GMA or urethane dimethacrylate (UDMA) in ____.
* Bowen, 1962
* Bonding mechanism occurs through taglike resin extensions that micromechanically interlock with the enamel microporosities created by etching.
78
True or false: acid etch removes about 10 microns of the enamel surface.
True
79
True or false: the hybrid layer in dentin refers to that area formed by the resin locking into the demineralized dentin. The resin of the adhesive system micromechanically interlocks with dentinal collagen.
True
80
True or false: the use of nonadhesive liners and bases beneath adhesive restorations is not recommended.
If you have a deep cavity preparation and you're close to pulp:
- put liner
- put glass ionomer base on top of liner
- composite can be bound on top of the glass ionomer, after doing total etch, and prime and bond
81
Steps for placing glass ionomer base
• Select light cure vs self cure
• Conditioner goes on before glass ionomer
- Polyacrylic acid that removes smear layer
• Place base avoiding preparation walls and cavosurfaces
82
Fundamental steps leading to treatment
* Med & social histories
* Chief complaint
* Clinical exam
* Radiographs
* Diagnostic models
* Diagnosis
* Treatment plan options
* Consent
83
Which cavities can involve any teeth, anterior or posterior?
* Class I
* Class V
* Class VI
84
A lesser number of blades on a bur results in...
More efficient cutting, but a rougher surface
85
Favorable factors for direct pulp capping clude...
1) visual evidence of uninflamed (pink) pulp tissue
2) absence of copious hemorrhage through the exposure
3) no previous symptom of pulpitis
4) a small non-carious exposure (a mechanical pulp exposure)
5) clean cavity, uncontaminated with saliva
86
Why is it important to restore proper proximal contact when restoring teeth?
1) to minimize periodontal pocket formation
2) to maintain the proper height of the interproximal papillae
3) to maintain the mesiodistal dimension of the tooth
4) to minimize food impaction
87
How does the presence of large size filler particles in composite resins affect the surface smoothness than can be achieved when polishing?
Reduces the degree of surface smoothness that can be achieved
88
What are some important points to remember when using a light to cure composite resins?
1) hold the light as close as possible to the resin
2) place a shield for eye protection
3) cure in 2 mm increments
4) darker shades need a longer curing time
5) routinely check light for polymerization effectiveness
89
The filler particles in composite are coated with _______ to promote adhesion to the resin matrix.
Silane
90
What determines the final outline of a class III preparation?
* Extent of the carious lesion
| * Access for removal of caries
91
For an anterior tooth fracture, if there is no caries or pulpal involvement what is recommended?
A bevel surrounding the enamel cavosurface is the only preparation necessary.
92
Are retentive pins necessary with today's resin composite restorations?
No
93
When is the best time to take a shade for a composite restoration?
Before rubber dam placement in natural daylight
94
What would you do if after you completed the composite restoration you notice that you need to add more composite material?
1) Etch
2) Bond
3) Add composite
95
When applying acid etch, what does NOT apply?
Apply to a clean, wet surface
96
When applying acid etch, what applies...
* Protect adjacent teeth
* Allow the etchant to make contact with the enamel for 30 seconds
* Allow the etchant to make contact with the dentin for 15 seconds
* Apply to a clean, dry surface
97
When applying the primer...
• Apply, air-puff to a thin shiny layer and light cure for 20 seconds
98
What can you do to minimize contamination to the composite material during placement?
* Wipe the rubber dam to remove ink from stamper before placing on the patient
* Dispense and manipulate the composite only with clean/sterile instruments
* Rinse the cavity preparation well to remove any debris
* Place anterior composite after gingival health has been restored
99
Why polish a restoration?
* Appearance: a glossy surface is more natural looking
* Feel: a smooth surface feels more comfortable to the tongue
* Stain: a smooth surface attracts less stain and is easier to clean
* Plaque: a smooth surface attracts less plaque and is easier to clean
100
Surface of a restoration will appear glossy when...
• If the width of scratches are less than the wavelength of light (0.35 microns)
101
Surface of a restoration will appear dull when...
• If the width of scratches are greater than the wavelength of light (0.70 microns)
102
Scratches that are wider than ___ microns can be seen with the unaided eye
20 microns
103
Surface of a restoration will feel smooth to the tongue if...
If scratches are less than 2 microns wide and deep
104
Surface of a restoration will feel slightly to moderately rough to the tongue if...
If scratches are 10 microns to 100 microns wide and deep
105
Surface of a restoration will feel very rough if...
If scratches are greater than 100 microns wide and deep
106
Sizes of scratches produced by abrasive particles...
* large particle produces similar scratches with lower applied force than smaller particle
* sharp particle produces deeper abrasion than rounder particle under applied force
* deeper and wider scratches are produced by increasing the applied force
107
Finishing and polishing sequence...
1) as placed --> initial rough surface
2) rough grinding [50-300 micron sized abrasives] ---> surface rough ground to contour
3) Prepolishing or "fine grinding" [5-50 micron sized abrasives] --> semi-smooth (matte) surface
4) polishing [< 2micron sized abrasives] --> final glossy surface
108
Composite surface is cured against a ______ _____.
Mylar strip
109
When the resin rich surface of the composite is worn during function, what is exposed?
Rough filler particles
110
Composites should be overcontoured during initial placement because...
* Results in properly polished composite
| * Filler particles are flattened into sample plane as resin
111
Polishing composites, recommended technique
1) Grind and contour (diamond stones, greenstones)
2) Prepolish (rubber-bonded abrasives and discs)
• Do not use finishing carbides or whitestones
3) Polish (diamond polishing paste on felt -- luminescence)
112
Role of water in dental procedures...
* Lubricant
* Washes away the abraded debris (prevents "blinding" of the abrasive)
* Keeps the surface from overheating, especially at high speeds
113
Uses for diamond instruments...
* Used in grinding and contouring composite restoration
* Tooth preparations (use plenty of water)
* Rough contouring composites
114
What is "Clean-A-Diamond"?
* Porous aluminum oxide blocks
| * Used for cleaning diamond instruments
115
Rubber bonded abrasives...
* Used in prepolishing of composite restoration
| * Great for lingual surfaces of anterior teeth and occlusal surfaces of posterior teeth
116
Sof-Lex Discs....
* Used in prepolishing of composite restoration
* Coarse, medium, and fine
* Flexible and tissue safe
* Great for prepolishing FLAT surfaces of composite restorations (facial of anterior teeth)
* Use only on the side opposite the blue color
117
Abrasive strips...
* Used for prepolishing interproximal areas of composite restorations
* Be careful to use these only BELOW the area of interproximal contact (otherwise, the contact will be lost!)
118
Luminescence...
* Polishing paste containing fine diamond particles (<1m)
* Final polish on composite restorations
* To be used only on a FELT tip
* Use with moderate pressure
119
Finishing and polishing DO's
ALWAYS:
• Use larger abrasive sizes first and use smaller and smaller abrasive sizes in sequence
• Use water ast he lubricant
• Rinse or wipe the surface clean between changes of abrasive sizes
120
Finishing and polishing DON'Ts
NEVER:
• Go from a rough surface (from larger abrasive sizes) directly to the final polishing step
• Attempt to grind, prepolish, or polish without using water as a lubricant
• Use a rubber bonded or plastic backed abrasive at high speed
121
Class V lesions are...
1) Caries affecting gingival 1/3 of facial or lingual surfaces of anterior or posterior teeth
2) Non carious cervical lesions
122
Shape of class V outline...
Trapezoid
123
Axial wall of class V prep is...
The axial wall is convex both in a mesio-distal and inciso-gingival dimension...
124
Location of gingival margin on class V prep...
The gingival margin is located approximately 1 mm from the free gingival margin.
125
Dimensions of a class V prep...
The preparation is 1.5 mm long in a gingivo-incisal dimension and 4mm wide in a mesio-distal dimension or within the facial line angles of the tooth.
126
Retention grooves in a class V prep are placed ...
Retention grooves are placed at the axio-gingival and axio-incisal line angles...
127
Class V composite preps are similar to class V amalgam except...
* Bevels are placed on cavosurface margins for a composite (M-D-I)
* Use of #212 cervical clamp with rubber dam (technique sensitive, moisture control)
* Use retraction cord, if necessary to establish your finishing line of the preparation
128
Bevels in a class V composite are...
* Situated entirely in enamel
| * Placed at a 45 degree angle, approximately 1 mm in width
129
Why place a bevel?
* To increase the surface area for etching
* To remove any unsupported enamel
* To decrease marginal leakage
* To soften transition of the restoration to tooth structure
130
Why do we not place a bevel on gingival margin of class V composite prep?
* If the gingival margin approaches the CEJ in close proximity, the enamel thickness may not be sufficient enough to accept a bevel
* A butt joint is the design of choice for the gingival margin
131
Retention in a class V composite is placed...
Entirely in dentin, not enamel
Note: retentive undercuts are needed in amalgam restorations, but not when adhesive restorations such as composites are placed (in lab we place undercuts.
132
Surgical retration such as gingivoplasty or miniflap should be done when...
When the rubber dam clamp cannot be positioned to provide complete access to the entire lesion without causing excess trauma to gingival tissue.
133
If caries are subgingival for class V, to get sufficient access to the lesion, what should be done?
Short vertical incisions are made within the keratinized tissue at the line angles of the tooth.
134
What helps to stabilize the #212 clamp?
Compound
135
Gingivectomy does what?
Exposes the clinical crown and provides access to the lesion.
136
What is adhesion or bonding?
* The attachment of one substance to another
* Complete isolation of the tooth is essential to achieve adequate bonding
* Adhesion to enamel is equivalent to adhesion to dentin if the proper technique is used
137
Describe etching...
* Method used on enamel & dentin to prepare it for bonding with composite
* 37% phosphoric acid gel is applied to enamel for 30 seconds and dentin for 15 seconds
* Rinse for 30 seconds, then dry GENTLY
138
Describe bonding agent...
* Bonding mechanism used to bond composite to tooth structure
* Apply to the etched surface and puff lightly with air to thin the layer
* Cure with the curing light (20 seconds)
139
Why is the resin composite placed in increments?
To compensate for polymerization shrinkage
140
Etiology of non-carious cervical lesion
```
• Has not been determined
• Cause is multifactorial:
- Erosion (chemical)
- Abrasion (mechanical)
- Abfraction or stress corrosion
```
141
Abfraction theory
Tooth flexure causes loosening of enamel rods which initiates the cervial lesion
142
Failure to prevent and treat NCCL can result in..
* Progression of tooth structure loss
* Sensitivity
* The need for endodontic therapy
* Tooth loss
* Occurrence of additional lesions
143
Define class I
• All pits and fissure cavities including:
- occlusals of PM and molars
- occlusal 2/3 on facial and lingual of molars
- lingual pits of maxillary incisors
144
Define class II
Proximals of posterior teeth
145
Define class IV
Proximal surfaces of anterior teeth AND incisal angle
146
Define class V
gingival 1/3 of all teeth on the facial or lingual surfaces
147
Define class VI
* Incisal edge of anterior teeth
| * Or, cusp tip of posterior teeth
148
Define class III
* Anterior 6 teeth - from the distal of the canine to the distal of the other canine (max or mand)
* Must include a proximal surface (mesial or distal)
* DOES NOT include the incisal angle
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Cones of decay for smooth surface and P&F caries...
* Pit & fissure: base to base
| * Smooth surface: apex to base (V, with tip towards pulp)
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Ways to diagnose lesions
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• Oral inspection
- Explorer
- Cavitation
• Transillumination
• Radiographs
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Types of class II preparations...
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• Lingual approach (MOST COMMON)
- Rectangular shaped
- Usually involves 2 surfaces (ML or DL)
- Can be 3 surfaces (MLB or DLB)
• Labial approach
- Triangular shaped
- Semilunar shaped
- Box (rectangular) shaped
```
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Indications for a lingual approach (class III)
* Facial enamel is conserved (preserved for esthetics)
* Color match is not as critical
* Future discoloration (staining) of the composite over time is less visible
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Indications for a labial approach (class III)
* The caries is positioned facially so a facial access would conserve tooth structure
* Teeth are aligned irregularly making lingual access not possible
* Extensive caries onto the facial
* An existing faulty restoration
* Missing adjacent tooth (direct access)
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Location of ideal class III prep
Decay typically starts apical the contact area, and so does the prep
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G.V. black steps to ideal prep...
* Outline form
* Resistance form
* Convenience form
* Removal of decay
* Retention form
* Finish the enamel
* Cleanse the prep
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Prep guidelines for class III
Lingual approach:
1) Located in the middle 1/3 I-G
• Incisal and gingival walls are within the middle 1/3
2) Proximal 1/4 M-D does not extend beyond the marginal ridge
3) Depth of the axial wall is to be 1/2 mm into dentin
4) the facial wall barely breaks facial contact
5) all internal line and point angles are slightly rounded
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Walls present in class III prep
* Incisal
* Gingival
* Axial
* Facial/linal
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Incisal wall of class III...
* Below the contact
* Parallel to the gingival wall
* Perpendicular to the long axis of the tooth -- Axial wall
* Perpendicular to the facial wall
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Gingival wall of class III...
* Parallel to the incisal wall
* Perpendicular to the long axis of the tooth and therefore to the axial wall
* Perpendicular to the facial wall
* Should have a short distance from the proximal cavosurface margin to the axial wall than the distance of the proximal margin of the incisal wall to the axial wall
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Axial wall of class III...
* Parallel to the long axis of the tooth
* As a guide for depth (proximity to the pulp) is 1/2 mm into dentin
* Perpendicular to the incisal and gingival
* Note that the depth/width of the incisal wall is deeper than the gingival (due to the thickness of the enamel)
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Facial wall of class III...
* Should be perpendicular to the axial, gingival, and incisal
* The cavosurface margin barely breaks facial contact
* Parallel to the facial wall of the tooth
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Margins on a class III prep...
* All margins are butt joints
| * The facial margin is beveled ONLY if it extends far enough facially to be visible
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What contacts are broken in an ideal class III prep?
* Facial and gingival contacts are broken
| * Incisal contacts are not broken
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Line angles are...
intersection of 2 walls
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Point angles are...
intersection of 3 walls
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Deviations/variations from the ideal class III prep are dictated by...
* Decay
* Tooth position/angulations/rotation diastemas
* Existing previous restorations
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Ways to obtain additional retention in class III prep...
1) Incisal and gingival walls of the prep should be slightly convergent in the facial to lingual direction; incisal and gingival walls should be slightly convergent convergent in a mesial to distal direction (from the axial to the cavosurface margin) for a distal class III restoration, and in the distal to mesial direction for a mesial class III restoration.
2) a minimal trough is placed in the incisal and gingival dentin, extending lingually --- 1/2 the diameter of a 1/2 round bur (use slow speed)
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When are bevels placed on a class III prep?
* A bevel should only be placed on the facial margin ONLY IF it extends far enough to the facial to be easily visible
* The lingual, incisal, and gingival margins are all butt joints -- no bevels placed
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Key points in a class III prep...
* All angles are 90 degrees
* I&G are parallel
* Protect the adjacent tooth
* Decay is below the contact
* Incisal contact is not broken
* Remove unsupported enamel
* Depth from cavosurface to the axial is 1/2 mm into dentin
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What is composite?
```
Resin with 4 components:
• Matrix (polymerized)
• Filler particles
• Coupling agent
• Iniator
```
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What is the composite matrix component?
* Mostly bis-GMA (bisphenol-A-glycidyl methylacrylate)
* UDMA (urethane dimethacrylate)
* Others (Bis-EMA)
* Matrix properties influence handling properties and shrinkage (volumetric)
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Composition of filler particles of composite...
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Usually glass of different sizes:
• Barium or borosilicate glass
• Zirconium oxide
• Aluminum oxide
• Silicone dioxide
```
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Particle sizes of filler particles of composite
* Macro filled - strong, not very polishable
* Hybrid - blend of submicron 0.04 um & small particle (1-4 um) somewhat polishable, good strength
* Micro filled - highly polishable
* Micro hybrids or nano-filled
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Purpose of filler particles in composite
* Improves translucency
* Reduces coefficient of thermal expansion
* Reduces polymerization shrinkage
* Increases hardness, density
* Makes composite more wear resistant
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Typical choice for class 3 restoration is...
Hybrid composite
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Coupling agent and initiator in composite...
• The fillers are covered with a silane coating to promote adhesion to the matrix
• Initiator - activates the polymerization reaction
- usually light
- chemical
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Effectiveness of curing light depends on...
* Wavelength of the emitted light, which should be 450-500 nm (blue light)
* Intensity of the bulb
* Light exposure time
* Distance from the light tip to the composite surface
* Shade of composite
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Restoration basics...
1) Be sure the tooth is clean: prophy and remove calculus if necessary, prior to prep & isolation
2) Shade selection - should be done prior to isolation, prep
3) Isolation with rubber dam
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Purpose of wedging...
* Separates the teeth
* Helps seal the gingival margin by pushing the mylar strip against the gingival margin and control the flow of excess composite
* Ensure proximal contact
* Protect interproximal gingiva
* Push the rubber dam gingivally
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Mylar strip/matrix should be placed _____ etching
BEFORE
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Enamel is etched for...
30 seconds
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Dentin is etched for...
15 seconds
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After etching...
* Wash/rinse off the etch for 30 sec (rinse for as long as you etched)
* Air dry lightly -- do not dessicate the tooth
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After rinsing and drying...
* Apply the bonding agent
* Using the microbrush gently rub the bonding agent on the tooth both enamel and dentin (apply more than 1 coat)
* Lightly blow air to avoid puddling of bonding agent
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After applying the bonding agent...
```
• Light cure
• Cure for a minimum of 10 seconds
• Start placing the composite
- small increments < 2mm at a time
- light cure 20 sec
- add
- cure till filled
- when placing the final increment fold over and hold the mylar strip, then cure
```
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Darker shades of composite need longer or shorter curing times?
Longer curing times
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Finishing and polishing class III...
```
• Start finishing by removing excess
• Coarse to fine
- Diamonds
- Finishing burs (multi-fluted)
- Sand paper disks (best on smooth flat surfaces such as incisal edges, facial surfaces)
• Keep the rubber dam on for this step
• Remove rubber dam and check occlusion
```
