Restorative Dentistry and Oral Rehabilitation Flashcards
(194 cards)
1
Q
Anatomy of Primary Molars
A
1) Enamel is thinner and more consistent depth
2) Relatively greater dentin thickness over occlusal fossa
3) Pulp horns higher (especially mesial)
4) Pronounced cervical ridges (especially buccal)
5) Enamel rods slope occlusally
6) Marked cervical constriction
7) Relatively longer, more slender roots
8) Roots flare out
2
Q
Characteristics of Crown of Primary Teeth
A
1) Shorter
2) Relatively wider mesiodistally
3) Narrower occlusal table
4) Cervical constriction
5) Broad, flat contacts
6) Prominent MB bulge
7) Incisors have no developmental grooves or mammelons
8) Thinner enamel
9) Enamel rods in cervical area are directed occlusally
10) Lighter in color than permanent teeth
11) Dentin tubules increase in diameter with depth toward pulp
3
Q
Implication of narrower occlusal table
A
Limits size of intracoronal restoration
4
Q
Implication of cervical constriction
A
Easy to lose proximal box of class II
5
Q
Implication of broad, flat contacts
A
Readily decay, prep wider to remove caries
6
Q
Implication of prominent MB bulge
A
Retention of a SSC, remove for zirconia
7
Q
Implication of incisors having no developmental grooves or mammelons
A
Simple to restore to natural contours
8
Q
Implication of thinner enamel
A
Caries spreads quickly to the pulp
9
Q
Implication of enamel rods in cervical areas being directed occlusally
A
No need to bevel gingival margin
10
Q
Implication of being lighter in color than permanent teeth
A
Use shade A1, B1 composite
11
Q
Implication of dentin tubules increasing in diameter with depth toward pulp; less interlobular dentin
A
Decreased bond strength with increased distance from DEJ
12
Q
Pulp in primary teeth
A
1) Relatively larger than permanent teeth
2) Pulp horns are closer to the outer surface
3) Great variation in size and location
4) Mesial (buccal) pulp horn is higher; particularly in mandibular primary molars - easy to knick with class II preparation
13
Q
Roots of primary teeth
A
1) Anterior roots narrower M/D than B/L
2) Molar roots are relatively longer, more slender than permanent teeth
3) Much more flared than permanent teeth
4) Branch directly from crown, with no identifiable root trunk
5) Larger apical foramina, many accessory canals
* * Pulpectomy may be difficult due to accessory canals/resorption
14
Q
Tooth-specific findings for maxillary central incisor
A
M/D crown width is typically greater than crown height
15
Q
Tooth-specific findings for maxillary lateral incisor
A
Longer than maxillary central
16
Q
Tooth-specific findings for maxillary canine
A
1) Wider, more symmetrical than mandibular canine
2) Cusp tip is offset to the distal
17
Q
Tooth-specific findings for maxillary 1st molar
A
1) Greatest dimension is B/L
2) Four cusps, but 2 distal cusps are diminished
18
Q
Tooth-specific findings for maxillary 2nd molar
A
Very similar to permanent counterpart, including cusp of Carabelli
19
Q
Tooth-specific findings for mandibular central incisor
A
1) Straight incisal edge
2) Narrowest primary tooth M/D
20
Q
Tooth-specific findings for mandibular lateral incisor
A
1) Wider, less symmetrical than mandibular central
2) Rounded incisal edge
21
Q
Tooth-specific findings for mandibular canine
A
1) Much narrower than maxillary counterpart
2) Height similar to maxillary counterpart
3) Cusp mesially displaced, with longer distal slope
22
Q
Tooth-specific findings for mandibular 1st molar
A
1) Wider M/D than B/L
2) 2 mesial cusps considerably larger than distal cusps
3) Prominent “S-curve” of gingival tissues
4) Broad contact between mesial 1st molar and canine
23
Q
Tooth-specific findings for mandibular 2nd molar
A
1) Very similar to permanent counterpart
2) Narrower buccolingually and less pentagonal than permanent 1st molar
24
Q
Objectives of restorative care
A
1) Restore damage caused by caries
2) Preserve remaining tissue, preventing pain/infection
3) Retain adequate function
4) Restore esthetics
5) Facilitate maintenance of good hygiene
6) Maintain arch length
25
Sensitivity
Ability to determine presence of caries when disease present
TP/(TP+FN)
26
Specificity
Ability to determine absence of caries when disease not present
TN/(TN+FP)
27
Nonselective/complete/conventional excavation
Carious dentin is completely removed at first visit
28
Stepwise excavation
1) Carious dentin partially removed at first appointment, caries left over the pulp, temporary filling placed
2) All remaining carious dentin removed at 2nd appointment
3) Reduces pulp exposures compared with complete excavation
29
Partial/incomplete/ultraconservative one step excavation
1) Caries is left over the pulp with a base and restoration placed in one visit
2) Reduces pulp exposures compared with complete excavation
3) More cost effective than stepwise excavation
30
Sealants: Epidemiology
1) 90% of caries in permanent teeth of children occurs in pits and fissures, and 2/3 occurs on the occlusal surface alone
2) Occlusal decay accounts for 44% of caries in primary teeth
31
Etiology of caries
1) Immature tooth enamel has high organic content, is more permeable, more susceptible to caries attack
2) Pit and fissure morphology facilitates plaque retention and bacterial proliferation
3) Enamel in pits and fissures is thinner and may experience accelerated demineralization
4) Molars erupt over 1.5-2.5 years (vs months for premolars), a period where cleansing of occlusal surface is difficult
5) Fluoride is less effective on occlusal surfaces than on smooth surfaces
32
Primary prevention
Intervention before evidence of disease = protects grooves from bacterial biofilm/food
33
Secondary prevention
Intervention after disease begun, before symptoms = inhibits progression of noncavitated lesions
34
Tertiary prevention
Intervention after disease is established = prevents decay from getting worse
35
E0 lesion
No radiolucency
36
E1, E2, or D1 lesion
Radiolucency may extend to the DEJ or outer one-third of the dentin
Note: Radiographs are not reliable for mild occlusal lesions
37
D2 lesion
Radiolucency extends into the middle one-third of the dentin
38
D3 lesion
Radiolucency extends into the inner one-third of the dentin
39
Glass ionomer sealant
- Calcium fluoroaluminosilicate or strontium fluoroaluminosilicate glass powder
- Aqueous-based polyacrylic acid solution
- Suggested in situations when isolation is difficult
40
Resin sealant
- Polymerized by chemical or photoinitiator
- Absorbs light at approximately 450-470 nanometers
- Chemically cured sealants set by means of a tertiary amine (activator) which is mixed with benzoyl peroxide, producing free radicals which initiates polymerization
- Some sealants contain filler: usually silicon dioxide microfilm or quartz
41
When to place sealants?
Except for high risk patients, sealant placement should be delayed until the gingival tissues are at or below the marginal ridge
42
Sealants and enameloplasty?
- Sealant placement should not require removal of enamel
| - Enameloplasty may remove the last enamel overlying dentin in pits and fissures, leaving the tooth more susceptible
43
PRR/CAR
```
PRR = preventive resin restoration
CAR = conservative adhesive restoration
```
Involves only removal of caries, with sealing of adjacent pits/fissures
44
When is resin infiltration indicated?
Noncavitated E1-D1 lesions
45
AAPD recommendation regarding resin infiltration
- From RCT, there is evidence in favor of resin infiltration as a treatment option for small, non-cavitated interproximal carious lesions in permanent teeth.
- Significantly improved the clinical appearance of white spot lesions and visually reduced their size.
46
Mechanism of action of Resin Infiltration
- Infiltrates the carious lesion pores
- Stops lesion progression by establishing a diffusion barrier
- Improves esthetics by replacing demineralized enamel with an infiltrant with a similar refractory index
47
Composition of Amalgam
- Silver (Ag)
- Tin (Sn)
- Copper (Cu)
- Zinc (Zn)
Approximately 50% mercury (Hg)
48
Purpose of Tin(Sn) in amalgam
Critical to setting reaction, controls dimensional change
49
Purpose of Copper(Cu) in amalgam
Prevents corrosion, reduces fracture
50
Purpose of Zinc(Zn) in amalgam
Acts as a scavenger for oxygen, forming Zn oxide in place of Cu/Ag/Sn oxides (weaken restoration)
51
Purpose of mercury (Hg) in amalgam
- Wets alloy and initiates setting reaction
| - When >54% Hg, strength is reduced
52
Gamma phase of amalgam
Unreacted alloy particles (mainly silver and tin)
53
Gamma one (amalgam)
Silver and mercury (Ag2Hg3)
54
Gamma two (amalgam)
- Tin and mercury (Sn7Hg)
- Responsible for early fracture and failure
- Copper replaces gamma two (Sn7Hg) phase with copper/tin (Cu5Sn5) phase, decreasing corrosion and preventing weakening/fracture
55
Types of amalgam
- Spherical
- Admixed
- Lathe-cut
56
Spherical amalgam
Amalgamates more readily, condenses more readily, requiring less mercury (42% vs 50%) than lathe-cut alloy and gaining strength more quickly
57
Admixed (comminuted) amalgam
Stronger proximal contacts
58
Marginal seal of amalgam
- Only restorative material in which marginal seal improves with time
- With old amalgam (low copper) gamma two phase created marginal seal
- With new amalgam (11-30% Cu) the eta phase (Cu6Sn5) oxidizes and transforms into CuCl2 and CuO2, taking twice as much time (2 years) to produce a similar marginal seal
59
FDA classification for amalgam
Class II device -- having some risk due to possible harm from mercury content
60
Mercury occurs naturally in 3 forms
- Elemental
- Organic
- Inorganic
61
Elemental mercury
Liquid at room temp, used in amalgam
62
Organic mercury
Methylmercury (most toxic) and ethylmercury - formed in water or soil by bacteria and can build up in fish
63
Inorganic mercury
- Enters air from mining or deposits, burning coal/waste, manufacturing.
- Generally exists in solid state.
64
Type of mercury that can be converted to methylmercury
ELEMENTAL and INORGANIC mercury may be converted to methylmercury intraorally by bacteria
65
Main human exposures to mercury
* Mercury vapor (Hg) from dental amalgam restorations
* Methyl mercury (MeHg) from seafood
* Inorganic mercury (I-Hg_ from food
*health hazard controversy has focused mostly on elemental and organic mercury
66
Threshold for health hazards from air/mercury
* 5 g/m^2 for adults
* 1 g/m^2 for children/pregnant women
**This is well below daily amalgam associated exposure
67
Amalgam safety
• Primary risk to dental personnel is from inhalation
• Exerted in feces and urine, and may pass to fetus and be detected in milk
- Dental personnel have been shown to excrete more mercury in urine than a control population
• Plasma and urine mercury levels considerably reduced by rubber dam use
- Far more mercury released when fillings are removed than when they are placed
- When removed, water spray and high-speed evacuation should be used
- Amalgam scrap should not be incinerated or subjected to heat sterilization
68
Indications for Amalgam
* Class II preparations that don’t extend beyond the line angles
* May be inappropriate for primary first molars in children 4 and younger
69
Amalgam prep design
* Amalgam has high compressive strength, low tensile strength, so cavity design is critical
* Ideal pulp floor depth = 0.5mm into dentin (1.5mm from enamel surface)
* Axial wall 0.5mm into dentin, following external contour, for a 1mm wide gingival seat
* Isthmus 1/3 of the intercuspal width
* Carved anatomy should be shallow to allow for adequate bulk of material
* Occlusal convergent buccolingual walls
* Proximal box is broader at cervical than occlusal; buccal, lingual, and gingival walls break contact
* Gingival wall should be flat, not beveled
* Most failures found in primary first molars, with OB margins most susceptible
70
Trituration and condensation
* Undertriturated mix (by time, most serious error) appears dry and sandy, sets too rapidly, has high residual Hg content
* Higher trituration speed gives shorter working time
* Condensation of back-back restorations should be completed simultaneously
* Amalgam gains strength slowly for 24 hours
71
Amalgam longevity
Historically the need for additional restorative treatment was approximately 50% higher when composites were placed vs amalgam
72
Three phases of composite resin
• Matrix phase (resin)
• Surface interfacial (continuous) phase
- Bipolar coupling agent (e.g. organosilane) or copolymeric/homopolymeric bond between organic matrix and partial organic filler
- Binds organic residen matrix to inorganic fillers
• Dispersed phase (reinforcement, filler)
73
Define monomer
A molecule that can react with other molecules to form a polymer
74
Define polymer
A substance consisting of a large number of similar units
75
Define oligomer
A polymer whose molecules consist of relatively few repeating units (e.g. dimer, trimer, tetramer). In contrast to a polymer, where number of monomers is, in principle, infinite
76
All composites have a dimethacrylate oligomer such as:
* Bis-GMA
* Urethanedimethacrylate (UDMA)
* Bis-EMA6 (larger molecule that decreases polymerization shrinkage)
* Siolorane monomer has been added to some composites, cleaves molecular rings, gains space and counteracts volume shrinkage
* Triethylene glycol dimethacrylate, a low-viscosity resin, is added as a dilutent (TEGDMA)
77
Chemically bonded fillers
```
• Quartz, colloidal silica (structure)
• Borosilicate glasses, glasses containing barium, strontium, zinc, zirconium (radiopacity)
• Classified according to filler size
- 1 nm = 1 x 10^-9
- 1 um = 1 x 10^-6
```
78
Microfilled
* Average 0.04 um (40 nm), micrometers, historically 50% filled by volume
* Can achieve better polish, more quickly, used for esthetic restorations (class V, resin veneers)
79
Nano
• 0.02-0.075 um (20-75 nm), include silane-coated SiO2 and ZrO
80
Hybrid
* Blend of 0.04 um (40 nm) and small particle 0.2-0.3 um (200-300 nm)
* Typical universal restorative materials
81
Microhybrid
• Average <1 um, typically 70-80% filler
82
Flowable
* 45-75% filler
* Increased shrinkage
* Greater wear
83
Smaller particle size of chemically bonded fillers results in?
Smaller particle size = polishability
84
Larger particle size of chemically bonded fillers results in?
Larger particle size = strength
| ** Substantially larger particles accelerate wear (when dislodged from resin matrix, significant material volume lost)
85
Order of size of chemically bonded fillers
Physical properties:
| Hybrids (40-300nm) > nano (20-75 nm) >> micro (40 nm)
86
Relationship of fillers and decreased wear of restoration
Packing filler particles closely results in less resin exposure and DECREASED wear
87
Relationship of fillers and polymerization shrinkage
More filler contributes to decreased polymerization contraction and thermal expansion
88
Replacing traditional monomers with larger molecular weight monomers (e.g. BisEMA6) results in what?
Less shrinkage
89
Indications for resin-based composite
* Class I restorations
* Class II restorations that don’t extend beyond the line angle, except when expected to exfoliate within 1-2 years
* Class II restorations in permanent teeth that extend approximately 1/3-1/2 B/L intercuspal width of the tooth
* Indirect resin restorations allow more complete polymerization of resin and reduced shrinkage
90
Contraindications to RBC
* Young children at high caries risk
| * Tooth cannot be isolated well
91
RBC technique
• No consensus regarding adhesive restoration prep design for primary teeth
- Some schools teach box-only prep
- Some schools tech GV black prep
• Some recommend a small dovetail or cavosurface margin bevel to increase surface area for bonding/retention. Beveling removes the aprismatic layer of enamel which may not etch well (leaving islands of unetched enamel that can act as pathways for bacterial leakage).
• Modifications to amalgam prep:
- Short bevel (not appropriate for amalgam)
- Retention groove/dovetail
92
How long to etch and rinse for composites?
* Etching enamel for 20-30 seconds
* Dentin no more than 15 seconds
* Rinse, leaving dentin moist to prevent collapse of exposed collagen network. Bond should be in contact for at least 15 seconds for most adhesive systems.
93
How to apply composite after etching, rinsing, and placing bond?
* Apply a thin (0.5-1mm) flowable composite liner to decrease voids at cavosurface of cavity margins.
* Only 2-4 mm increments of conventional composite at a time.
* Best contact for back-back restorations can be achieved by completing one restoration at a time.
* Dovetails are recommended on F/L of primary canines and on primary incisors.
* Most RBC systems have 1-5.7% polymerization shrinkage (newer composites have lowered this)
94
Etchant
* Etching overcomes smear layer, obstruction of dentin tubules
* Etching primary tooth dentin for shorter times may produce same results as longer times for permanent teeth
* No significant difference between resin bond strength for enamel etched for 20 or 60 sec
* Liquid and gel etchant produce similar results
95
Adhesives composition
Solutions of resin monomers with hydrophilic groups and hydrophobic groups
• Two groups (both infilled dimethacrylates):
- Halophosphorus esters of Bis-GMA, Bis-GMA more hydrophobic
- Halophosphorus esters of hydroxyethyl methacrylate (HEMA), HEMA totally miscible in water
- Both rely on phosphate-calcium bond for retention
• Solvents are added as thinning agents: water, ethyl alcohol, butyl alcohol, acetone. Must be displaced by drying or will be incorporated into bonding layer.
96
Type of bond created between adhesive and dentin
Mechanical bond created when smear layer removed, monomers infiltrate into demineralized dentin, polymerize and interlock within dentin matrix = hybrid layer between intact dentin and resin adhesive
• Little if any evidence to support chemical bond to dentin, relies on micro mechanical retention
• Several studies show that bond to primary dentin is similar to permanent tooth dentin
• Should be placed after glass ionomer base/liner (see sandwich technique)
- Unfilled bis-GMA bonding agent will bond to GIC base/liner
97
Adhesive generations
```
• 4th gen: (Etch), (Primer), (Bond)
- Scotchbond Multi-Purpose
- Optibond
• 5th gen: (Etch), (Primer + Bond)
- Prime & Bond
• 6th gen: (Acidic Primer) + (Bond)
- Clearfil SE
• 7th Gen/Universal: (Acidic primer + adhesive)
- **May also total etch**
- Scotchbond Universal
```
98
Which type of adhesive generation is good for sedation patients?
6th generation good for sedation patients; no rinsing required
99
Physical properties of glass ionomer
* Chemical bonding to enamel and dentin
* Thermal expansion similar to the tooth
* Less shrinkage than resin based composite
* Uptake and release of fluoride (may occur for at least a year and can act as a fluoride reservoir)
* Hydrophilic, with decreased moisture sensitivity compared to resins
* **The only dental materials currently in use that have the potential for true adhesion to tooth structure and clinical record of success**
100
Three general categories for glass ionomers
* Type I = luting
* Type II = restorative
* Type III = base/liner
101
GIC composition
* Calcium or strontium alumino-fluoro-silicate glass powder (base)
* Polyacrylic acid (water soluble polymer) (acid)
* Calcium and aluminum ions bind to polyacrylic acid, initiating a gel phase. Fluoride is released.
102
Hardening reaction of glass ionomer involves what?
* Hardening reaction involves neutralization of acid groups by powdered glass base.
* Significant amounts of fluoride ions are released during the reaction
* Requires the presence of water
103
How does glass ionomer bond to dentin?
• Bond to dentin via free hydrophilic carboxyl groups in the cement forming hydrogen bonds at the tooth surface
104
What happens if glass ionomer cement is mixed too thick?
If cement is mixed too thick, insufficient water will be available to complete reaction and dentin sensitivity will be encountered as water is taken from dentin.
105
Evidence for GIC
* Based on systematic review and meta-analysis, conventional GI not recommended for class II restoration in primary molars
* Adhesion to tooth surface is greater than orthodontic bands or crowns. Roughening internal surfaces may improve retention.
106
Resin Modified Glass Ionomer (RMGI)
* Conventional glass ionomer formulation with addition of resin monomers or co-monomers of acrylic acid and a methacrylate such as hydroxyethyl methacrylate (HEMA)
* Acid-base polymerization supplemented by resin light cure polymerization
* Achieve same properties of conventional GI, with improved wear resistance and esthetics + command cure
107
RMGI demonstrate “triple hardening”
* Initial curing of light sensitive resin
* Chemical resin cure
* GI acid/base neutralization matures over time
108
Dentin conditioning and RMGI
After tooth preparation dentin conditioning varies according to manufacturer:
• Polyacrylic acid removal of smear layer
• Self-etching adhesive, with light cure
109
Sandwich technique for RMGI
```
GI or (usually) RMGI is used to replace dentin, composite is overlaid as a bonded enamel replacement
• Ionomer bonds adhesively to tooth, bonding agent bonds mechanically between ionomer and enamel
```
110
Advantages of sandwich technique with RMGI
* Decreased marginal leakage at margins
* Reduced post-op sensitivity
* Reduced effect of polymerization
* Improves esthetics over GI/RMGI only
111
Evidence for RMGI
* May be considered for class I and class II restorations in primary teeth
* Permanent teeth with class V lesions are ideally suited for RMGI
* Conditioning dentin may improve success rate
* Cavosurface beveling leads to high marginal fracture and is not recommended
* Insufficient evidence for long-term restorations in permanent teeth
* RMGI has less wear resistance and lower fracture strength than resin based composite
* RMGI placed without occlusal dovetail (box-only) more likely to show adhesive failure
112
Compomer (polyacid modified resin composite)
* 72% strontium fluorosilicate glass (average size 2.5 micrometers)
* Glass filler particles and dehydrated polyacid are incorporated into resin matrix, releasing fluoride (considerably less than GIC)
* Do not “recharge” with fluoride like GIC
* Not considered to be hydrophobic
* No bond to tooth structure (must be used with an adhesive)
113
Evidence for compomers
* May be an alternative to other primary tooth filling materials, but not enough data to compare compomers to other restorative materials
* According to manufacturers, enamel etching is not required when placing compomers, however lab studies show higher bond strength and better marginal adaptation when the enamel was acid etched
* Compomers are used in conjunction with methacrylate primers that bond to enamel, dentin, and compomer restorative material
* Mechanical properties: RBC > Compomers > GIC
114
What are bioactive materials (ACTIVA)?
* ACTIVA/BioActive restorative and ACTIVA BioActive Base/Liner
* Approval by FDA to be marketed as a RMGI filling material
115
Composition of BioActive Materials (ACTIVA)
* 56% filler restorative, base/liner 45%
* 21% bioactive glass filler
* BioActive ionic resin matrix (Embrace resin, which is “moisture friendly”)
* Rubberized resin (shock absorption)
116
Propertiies of Bioactive Materials (ACTIVA)
* Chemically bonds to teeth
* No Bis-GMA and no BPA derivatives
* Releases calcium, phosphate, and more fluoride than glass ionomers (per ACTIVA product info)
* Reportedly greater deflection to break than composite or RMGI
* Light cure (20 sec), chemical cure (2 min)
117
Technique for Bioactive Materials (ACTIVA)
* Etch prepared teeth for 10 sec
* Use a bonding agent in non-retentive cavity preparations
* Dispense directly into preparation and allow material to be in contact for 20-30 sec before curing
* May be applied in increments up to 4mm (20 sec cure between each layer)
* May be used in sandwich technique
118
Composition of stainless steel crowns
* Typically 316 stainless steel (surgical grade, as used in orthopedic surgery)
* Old generation up to 72% nickel, 8% iron (3M ion Ni-chro)
* New generation: iron (65-73%), 17-19% chromium, 9-12% nickel, < 2% manganese, silicon, and carbon (similar to orthobands/wires)
119
Indications for SSCs
* After pulp therapy
* Multisurface caries in high risk patients
* Proximal box that extends beyond line angles
* Fractured teeth
* Teeth with extensive wear
* As an abutment for a space maintainer
* For multisurface lesions when a restoration is expected/needed to last longer than 2 years or when the patient is younger than 6
120
Contraindications to SSCs
* Patients who will be undergoing magnetic resonance imaging of the head and neck
* Patients with nickel allergy (should 1st be seen by a dermatologist)
* Teeth exfoliating in 6-12 months should not receive an SSC
121
Indication of SSC in permanent teeth
* Interim restoration
* When finances do not allow a lab-fabricated crown
* Teeth with developmental defects
* A permanent tooth that requires full-coverage but is only partially erupted
122
Technique for SSCs in permanent teeth
* 1.5-2 mm reduction
* Preferable to check crown size before preparation, as there are fewer sizes available when compared with primary teeth
* Cannot be left in supraocclusion
* Original tooth morphology should be restored with a build-up before crown cement action
* BW radiograph is recommended at final try-in before cementation
* Adolescent patients with permanent molar SSCs have increased sulcular depth and gingivitis
123
Longevity and clinical success of SSCs
Many studies have compared SSC with amalgam and composite
• Generally SSCs are shown to have the highest success rates, with many studies showing significantly better results (95% survival compared to 50%)
• 2002 review concluded SSCs superior in durability and longevity to class II amalgam and composite
• The failure rate of class II amalgams ranged from 2-7 times that of SSCs, with amalgam restoration failure rate being a mean 4 times more than that of SSC restorations. There was a rate of 1.5-9 failed amalgams for every failed SSC.
Dentists spend approximately 50-60% of their time replacing restorations:
• Some studies suggest that cost-per-patient is lower when teeth are restored with SSCs due to fewer replaced restorations
• Main reasons for failure are crown loss and perforation
124
Gingival health around SSCs
* Crowns with poorly adapted margins show gingivitis
* Extension of crown not associated with gingival health
* Poor oral hygiene most associated with unhealthy gingiva around SSCs
125
Restoration after pulp treatment
* Studies have consistently shown SSCs demonstrate better long-term outcomes than composite restorations following pulp capping or pulpotomy
* Recently MTA has shown nearly equivalent results when used with bonded composite restorations
126
SSC technique
* Placement of wooden interproximal wedges to protect adjacent teeth and depress gingival tissues
* Occlusal reduction of 1.5 mm, maintaining occlusal contour (must allow for 1mm of clearance with the opposing tooth)
* Proximal reduction without ledges, ending slightly below gingivae in enamel in feature or knife edge margin
* Round all line angles
* Minimal buccal and lingual reduction, unless pronounced convexity is present or in space loss situations when smaller crowns must be fitted
* Crown should seat subgingivally about 0.5-1 mm
* 1-1.5 mm high in occlusion is acceptable
* All preparations should be completed with rubber dam, except the distal slice
127
Cementing SSCs
* Most evidence is from laboratory studies, which may not replicate real-world conditions
* Bonded resin cement has greater tensile strength and retention with least microleakage but may have practical drawbacks due to isolation concerns
* GI or RMGI acceptable (no significant difference in retention)
* RMGI may be used with bonding agent to increase retention
128
How to patch perforated crowns
Perforated crowns can be patched with composite, GI, or RMGI. Resin patches may have greater microleakage.
129
Luting cements for SSCs
* Zinc phosphate
* Polycarboxylate
* GIC
* Resin Cements
130
Zinc phosphate luting cement for SSC
* Phosphoric acid liquid + zinc oxide powder
| * Does not adhere to tooth structure or have anticariogenic effect
131
Polycarboxylate luting cement for SSC
* Zinc oxide + polyacrylic acid or a copolymer of that acid
| * Forms a chemical bond between cement liquid and calcium in the hydroxyapatite in tooth
132
GIC luting cement for SSC
* Acid has potential for bonding to calcium like polycarboxylate
* Fluoride release similar to silicate cement
* Type I GIC, liquid acid is freeze-fried and combined in the powder
* Accessible margins should be covered with varnish after placement
* Can cause post-op sensitivity due to low initial pH and relatively slow set
133
Resin Cements
* Can be viewed as lightly filled composites, similar to fit/fissure sealants
* Used extensively in all-ceramic crowns and inlays
134
Purpose of bases and liners
* Reduce marginal microleakage and prevent sensitivity
| * Minimum 0.5 mm needed to provide effective thermal insulation
135
Bases and liners: Calcium hydroxide
* Catalyst paste: Ca(OH)2, zinc oxide, zinc stearate in ethylene toluene sulfonamide
* Base paste: calcium tungstate, calcium phosphate, and zinc oxide in glycol salicylate
* Form an amorphous calcium dysalicylate
* Alkaline pH aids in preventing bacterial invasion
* May experience hydrolysis due to fluid contamination from dentinal tubules and microleakage
* After hydrolysis, gingival displacement of restoration may lead to restoration breakdown
* When Ca(OH)2 is used, a less soluble high-strength base should be placed
136
Bases and liners: cavity varnish
* Historically placed under amalgam restorations and before zinc phosphate cement to reduce microleakage and sensitivity
* Not placed under composite/GIC
137
Bases and liners: zinc oxide-eugenol (IRM)
• Powder: zinc oxide, rosin, and zinc acetate
• Liquid: preparation of eugenol
• Forms an amorphous chelate of zinc eugenolate
• Has a sedative effect
• Low compressive strength
• Polymer-reinforced zinc oxide-eugenol (poly-methyl- methacrylate) used for obliterating pulp chambers of primary tooth pulpotomy
*** Eugenol is an inhibitor for polymerizing resins and can interfere with cements, restorative materials, and even impression materials ***
138
The Hall Technique
* Typically provided with no caries removal, no local anesthesia, no preparation.
* Studies show better outcomes for HT crowns than intracoronal restorations
* No significant difference between success for HT crowns and traditional SSCs
* HT crowns open occlusion, but it returns to pre-treatment levels in 15-30 days. Likely due to intrusion of the molar and opposing tooth.
* More negative behavior in children who received conventional restorations.
* Noted by 2015 review as having good quality evidence and is a valid technique for SSC placement.
139
Alternative/atraumatic restorative technique (ART)
* Endorsed by the World Health Organization as a means of restoring and preventing caries in populations with little access to traditional dental care
* Typically used in situations that do not allow for follow-up care
140
Interim Therapeutic Restoration (ITR)
• May be used to restore, arrest, or prevent the progression of carious lesions in young patients, uncooperative patients, or patients with special health care needs or when traditional cavity preparation and/or placement of traditional dental restorations are not feasible or need to be postponed
141
ITR technique
* Fluoride releasing materials
* Anesthetic is usually not used
* Minimal tooth structure is removed
* Decay often remains
142
ITR vs ART differences and similarities
• Different therapeutic goals
- ART: restoring/preventing caries in populations without access to traditional care
- ITR: restore, arrest, or prevent progression of lesions (with anticipated follow-up)
• Shown to reduce levels of cariogenic oral bacteria (may return to pretreatment levels within 6 months)
• Employs hand or rotary instruments
• Caries removed from periphery of lesion, but may be left at the base
• Failure common with inadequate cavity preparation, lack of retention, and insufficient bulk of material
143
Benefits of rubber dam isolation when compared to alternative isolation systems such as Isolite, Dryshield, Mr. Thirsty
* Protection from debris and dropped instrument (++)
* Retracts gingival tissues (+)
* Reduces talking (++)
144
Benefits of alternative isolation systems such as Isolite, Dryshield, Mr. Thirsty
* Ability to isolate partially erupted teeth (++)
| * Saves time (++)
145
Esthetic dentistry/Prosthetic Replacement
* Space maintenance is not typically required for incisors
* Best to allow 6-8 weeks following tooth loss before appliance fabrication, however, may be placed on day teeth are extracted
* Bands, or preferably SSCs, on primary molars are abutment for anterior pontic teeth
E.g. Groper pediatric partial
146
Esthetic dentistry/Prosthetic Replacement: Diastema closure
* If the patient is in orthodontic treatment, dentist may advise orthodontist regarding optimal arrangement of teeth for closure. Patient then completes active treatment and placed in retention before closure.
* For some patients the best treatment may be partial diastema closure, or teeth may become excessively wide.
* Authors recommend restoration of one tooth to full contour followed by 2nd tooth to match
147
Microabrasion: esthetic treatment of hypoplasia
* Best for isolated brown/white areas in otherwise normal enamel
* Enamel micro abrasion: hydrochloric acid (6.6%) in slurry of silicon carbide microparticles (Ultradent). 1mm thick increments. Apply heavy pressure with slow speed using polishing cup.
* Follow with fluoride treatment.
148
Full coverage restoration of permanent teeth
* Reduction of all-ceramic restoration less than metal ceramic (e.g. 1.5mm vs 2.0mm incisal reduction)
* Posts and cores do not strengthen teeth. Indicated only when inadequate structure remaining for definitive restoration.
149
Veneers for permanent teeth
* May require removal of 0.3-1.0mm tooth structure depending on degree of stain and cosmetic masking
* Typically cemented with photopolymerized or dual-polymerized resins
150
Vital bleaching
* Peroxide diffuses through enamel to stained dentin
| * 10% carbide peroxide = 3.3% hydrogen peroxide
151
Vital bleaching at home
Home bleaching with milder carbamide peroxide (e.g. Ultradent Opalescence, 10%)
152
Vital bleaching in-office
In-office power bleaching: concentrated hydrogen peroxide (e.g. Ultradent Opalescence Boost 40%) with rubber dam, heated with electric lamp or laser (some manufacturers)
153
Dental implants
• Due to growth concerns, missing teeth in children are typically managed with partial coverage prosthesis (e.g. Maryland bridge), resin-bonded restorations, or removable prosthesis
- An implant behaves like an ankylosed tooth, and in the context of growth, may become buried because it doesn't erupt normally.
- When implants are placed before growth is complete, it is more predictable to restore larger edentulous areas than to place single-tooth implants
• Two main issues:
- Impact of growth on relative position of the implant
- Effect of the implant-supported prosthesis on dental and skeletal growth
• Implants have been placed in the anterior mandible as young as 5 years of age, which may decrease alveolar resorption caused by a removable prosthesis
154
Ectodermal dysplasia and implants
Young patients with ectodermal dysplasia may benefit from implants:
• Less saliva, mucosal drying --> poor retention of conventional prosthesis
• Absence of teeth --> less bone, potential need for grafting
155
Maxillary growth and implants
Transverse growth influenced by increasing width of cranial base and growth of median suture:
• Early placement of implant can give rise to a diastema
• Early placement of a prosthesis that crosses the midline can inhibit growth
Resorption occurs at the anterior surface of the maxilla, bringing it downward and forward:
• Early placement can result in loss of labial cortical bone
Natural teeth experience spontaneous mesial drift with growth, implants do not
Vertical growth is last to complete:
• Early placement can lead to implant in nasal floor after puberty when permanent teeth have moved down
156
Mandibular growth and implants
• Transverse growth of the mandible completes very early, with closure of the symphysis in the 1st year of life
• Posteriorly there is lingual resorption and buccal deposition
- Can lead to lingual positioning of the implant if placed too early
157
Average pubertal growth spurt
Wide range of pubertal growth spurt
• Boys 11-17 years
• Girls 9-15 years
158
Assessing growth
* Serial cephalometric tracings taken 6 months apart can be superimposed to ensure growth has taken place
* Hand wrist radiograph can determine when growth of long bones is complete, and facial growth also likely finished.
159
Screw retained implants
* Screw retained implant crowns may offer a benefit in a patient where it is not absolutely certain growth is finished
* Crowns can be removed easily
* If adjacent teeth continue to erupt, crown can be removed and porcelain added to the incisal edge
160
Problem with esthetic posterior SSCs
Consistently the major problem is chipping and loss of preveneered facings
161
Technique for esthetic posterior SSCs
```
• 1.5-2 mm occlusal reduction
• 1-1.5 mm circumferential reduction, including removal of bulges and heights of contour
• Avoid over tapered preparation
• Failure to seat to the height of the adjacent unprepared tooth:
- Inadequate occlusal reduction
- Excessive crown length
- Gingival ledge
- Inadequate M/D space
```
162
Class III restorations in primary incisors
* Small clinical crowns
* Large pulp chambers
* Thin enamel in close proximity to pulp
* May benefit from labial or lingual dovetail and veneering entire labial or lingual surface
163
Indications for full-coverage restorations in primary incisors
* Multiple carious surfaces
* Incisal edge involvement
* Extensive cervical decalcification
* Pulpal therapy
* Hypoplastic enamel
* Poor moisture or hemorrhage control
* Large single-surface lesions
* Very poor oral hygiene
* Discolored incisors that are esthetically unpleasing
164
Build-up after pulp therapy for primary incisors
May include composite into canal space, glass fiber-reinforced posts, orthodontic wire bent into an omega shape
165
Full coverage crown materials
Polycarbonate
• Heat-molded acrylic resin
• No long-term studies and very limited use in the US
Composite crowns first restorative choice of 46% of pediatric dentists for incisors
• Durability is a major concern
• Retention is 80% at 24-36 months
166
Advantages of Zirconia Crowns
* Highest strength of any pediatric crown type
* Biocompatible
* Color-stable
167
Cementation of zirconia crowns
1) Manufacturers recommend a high performance luting cement:
• Resin cement
• Resin modified glass ionomer
• Glass ionomer
2) Achieve hemostasis
3) Fill crown forms 3/4 full
4) Cement all crowns at same time
5) Remove excess cement
168
Most common cause of lower face swelling
Most commonly due to dental infection
169
Cause of upper face swelling
May have multiple causes
170
Odontogenic infections and antibiotic therapy
* Indicated for elevated temperature (102-104 deg F), facial cellulitis, difficulty breathing or swallowing, truisms, fatigue, nausea
* IV antibiotics, incision and drainage, and referral/consult with OS may be indicated
171
Complications of odontogenic infections
* Ludwig's angina: involves submandibular, submental, and sublingual spaces
* Cavernous sinus thrombosis
172
Canine space
* Maxillary canine
* First premolar
* Primary 1st molar
173
Buccal space
* Upper bicuspids
* Upper primary molars
* Lower molars
* Lower bicuspids
* Lower primary molars
174
Submasseteric space
* Lower 3rd molars
| * Fracture of angle of mandible
175
Pterygomandibular space
* Lower 3rd molars
| * Fracture of angle of mandible
176
Sublingual space
• Lower bicuspids
• Lower molars
• Direct trauma
** Contains sublingual glands, Wharton's ducts, lingual a.n., sublingual a.v., hypoglossal n.
177
Submandibular space
* Lower molars
| * Contains submandibular gland, facial a.v., lymph nodes
178
Submental space
* Lower anterior teeth
* Fracture of symphysis
* Lower bicuspids/molars
179
Danger space
• The danger space is a potential space located behind the true retropharyngeal space
• Boundaries:
- Superiorly by the skull base
- Anteriorly by the alar fascia
- Posteriorly by the prevertebral fascia
- Ends at the level of the diagphragm
180
Consequences of fractured primary roots
* Increased chances of infection
* Delayed eruption of permanent successor
* Removal can cause damage to succedaneous tooth
181
Recommendation regarding fractured primary roots
If root tip can be easily removed it should be. If it is very small, deep, or close to permanent tooth, unable to be retrieved after multiple attempts it should be left to be resorbed.
182
Most frequent unerupted/impacted teeth
3rd molars > maxillary canines
183
Should impacted 3rd molars be extracted?
No evidence to support or refute removal of disease-free impacted 3rd molars
184
Sector analysis for primary canines/laterals
* Extraction of primary canines indicated when permanent canines is mesial or overlapping lateral incisor root.
* If no improvement in canine position in 1 year, surgical/ortho treatment suggested.
185
Supernumerary teeth
* In 1/3 of cases a primary supernumerary is followed by a permanent supernumerary
* 3% in primary teeth, up to 15% in permanent teeth
* Males twice as likely as females
* 10 times more likely in maxillary arch than mandibular
* Frequency = mesiodens > paramolar (maxillary molar area)
186
How to determine location of supernumerary teeth
Location can be determined with Clark's rule/buccal object rule or CBCT
187
Percent of mesiodens that erupts spontaneously
25% of mesiodens erupt spontaneously (conical uninvited mesiodens best chance of eruption)
188
When to extract supernumerary?
Recommended extraction during the mixed dentition when 2/3 root formation complete to allow normal eruption of permanent teeth with least risk of developing teeth
189
Ankyloglossia
* Prevalence of 4-10.7%
* Frenectomy is supported by the literature as improving breastfeeding and reducing maternal nipple pain
* Speech therapy in conjunction with frenuloplasty of frenectomy can improve tongue mobility and speech
190
Maxillary frenum attachments
* Mucosal = attachment at mucogingival junction
* Gingival = insertion into attached gingiva
* Papillary = insertion into interdental papilla
* Papilla penetrating = insertion up to palatine papilla
191
Maxillary frenectomy indications
Tx suggested when:
- blanching occurs when upper lip is pulled
- >2mm diastema
- Generally not recommended before age 11-12, when permanent canines have erupted
192
Hemostasis
Absorbale gelatin sponge (Gelfoam), absorbed by body over 4-6 weeks
193
Suture -- Needles
Needles
• Reverse cutting needles for keratinized gingiva
• Tapering needles for non-keratinized gingiva
• Monofilament materials for skin, to minimize scarring/tissue reaction
194
Suture -- Materials
* Chromic gut = effective strength for 5 days in oral cavity
* Polyglycolic acid (vicryl) = good strength for 2 weeks, may accumulate plaque due to braided nature
* Monofilament nylon = very clean, but must be removed
* Silk = braided, must be removed, use decreased due to the availability of polyglycolic acid
