Resin-based restorative materials Flashcards
What is the most used restorative material?
composite
What is organic resin matrix disperesed by?
inorganic fillers bound to the resin by a silane coupling agent and an initiator-accelerator system
What are the different resin matrixes?
- Bis-GMA
- UDMA
- TEGDMA
What are the benefits of filler particles?
- Reinforcement of resin matrix
- DECREASED polymerization shrinkage
- DECREASED thermal expansion and contraction
- Viscosity control
- DECREASED water sorption
- INCREASED radiopacity
What in the filler increases the radiopacity?
Barium
Strontium
Zirconium
________ filler amount reduces the thermal expansion and contraction coefficients
Higher
The reduced shrinkage is proportional to the filler ________
volume
What is the coupling agent?
silane
The interfacial bridge forms between what?
the resin matrix and the filler
What is the point of the coupling agent/interfacial bridge?
✓ Better stress distribution between resin matrix and filler particles
✓ Improvesthe mechanical properties
✓ Decreased watersorption along filler-resin interface
Composites require that monomers to coverted into
polymers
What triggers the composite convertion from monomers to polymers?
free radicals
What is the activator for chemical/self-cure composite?
tertiary amine
What is the initiator for chemical/self-cure composite?
Benzoyl peroxide
What is the reaction for a chemical/self-cure composite?
What is the activator for light-cured composite?
blue light (465 nm)
What is the initator for light-cured composite?
- camphoroquinone (photosensitizer)
- DMAEMA (amine)
What are the characteristics of regular (conventional/packable) composite?
- 80-85% filler
- many applications, versatile, laying technique, more esthetic
What are the characteristics of flowable composite?
- 40-60% filler
- polymerization shrinkage
- under regular comp class II
What are the three classification by handling characteristics?
- regular
- flowable
- bulk fill
What are the characteristics of bulk fill composite?
✓ Developed to enable restoration in single increment built up to 4-5 mm
✓ Increased depth of cure
✓ Reduced polymerization shrinkage stress
✓ Improved adaptation to the surface of the cavity
✓ Simplified placement technique compared to regular composites (incremental)
How do bulk fill composites achieve a depth of cure (polymerization)?
- Reduced filler amount
- Increased filler particle size
- Alternative photoinitiators
How do bulk fill composites achieve modulate the polymerization reaction?
- Altered filler particles
- Presence of stress-relieving monomer
What are the filler particles for bulk fill composites like?
- Lower amount of filler particles
- Pre-polymerized filler particles (similarly to microparticules comp)
- Low elastic modulus = help to absorb stresses
- Added larger filler size particles
What are the monomers for bulk fill composites?
- UDMA
- Modified UDMA (adding aromatic groups)
- Fragmentation dimethacrylate monomers
What is the typical path of polymerization of methacrylate?
- pre-gel phase (elastic deformation)
- gel phase (converting to solid)
- solid (polymerization shrinkage)
What is flowable bulk fill?
- Flowable consistency
- Lower elastic modulus and reduced wear resistance (mechanical properties)
- Base for regular composites as the occlusal increment
- Dentin replacement only
- Better adaptation on the surfaces of the cavity
What is full body bulk fill?
- Suitable wear resistance (better mechanical properties)
- Replace dentin and enamel
- Possibility of sculpture
- Single increment (up to 4-5 mm)
Where are the clinical applications of bulk fill composite?
- posterior restorations (class I and II)
- some specific class III cases
What is the process for bulk-fill flow?
- Filling the cavity (~2 mm to regular comp.)
- Wait the flowability of the material
- Light-cure
- Place and sculpt using regular composites
- Light cure
- Finishing
- Polishing
What is a sonic activated bulk fill?
- Rheological modifiers react to the sonic energy applied during placement
- Cavity adaptation keeping the mechanical properties
What is the dual cure bulk fill?
- Dual cure system: chemical (two pastes – automix) and light-cure
- Single increment (class I and II)
Why is finishing and polishing bulk fill composites good?
*Decrease the coefficient of friction = reduced rate of wear
*Less bacterial adhesion = less marginal leakage = less possibility of secondary caries
* Color stability = reduce staining (body and marginal)
Majority of contouring and finishing of a bulk fill composite should be completed…
PRIOR TO LIGHT CURING
What are the advantages of bulk fill composite?
- Simplification of the restorative technique
- Reduced chair time
- Better flowability = cavity surface adaptation
- Suitable mechanical properties
- Reduced polymerization shrinkage stress
What are the disadvantages of bulk fill composite?
- Overall, bulk fill are more translucent than regular composites
- Indicated for posterior restorations
- Cannot mimic the natural layering of tooth
What is a resin-modified glass ionomer (RMGI)?
Acid- base, self-adhesive materials, combining fluoro-aluminosilicate glass powder and polyacrylic acid liquid.
What are the fluoride properties of resin-modified glass ionomer (RMGI)?
Fluoride recharging when exposed to oral environment, “theoretically” indicating their use in patients with high caries risk (minimal esthetic demand)
What is the reaction for resin-modified glass ionomer (RMGI)?
- Ionization of polyacrylic acid in water
- Light cure
- Initial setting (gelation; salt bridge formation)
- Light cure
- Final setting
- Light cure
- Maturation
What is the triple cure system for RMGI?
Acid-base reaction
+
Light cure (free radicals by light activation)
+
Free-radical by chemical activation
✓ HEMA redox (catalysts)
What are the properties of RMGI?
✓ Fluoride release and recharge
- Interact with aggregation of biofilm
- Increase release in acidic situations
-Increase the pH
✓Bioactive / Biointeractivity
- Release of Na, PO ions, SiO
✓ Improved working and setting times (compared to conventional GIs)
✓ Mechanical properties
- Low cohesive strength
- Limited strength and wear resistance
- Lower to CR and higher to conventional GIs
✓ Esthetic properties
- Lower to CR and higher to conventional GIs
What are the applications of resin-modified glass ionomer (RMGI)?
- Liner material
- Base material (under amalgam, gold, ceramic, and composite restorations)
- Low-stress areas (not typical for Class I, II or IV rest.)
- Where caries is a concern
- Root-surface caries lesions (primary indication)
- Slot like Class II or III cervical locations (not proximal contact)
- Non-carious cervical lesions Class V (if esthetic is not critical)
What are noninvasive resin infiltrants?
microinvasive surgery
- Microinvasive: barriers to prevent further dissolution of enamel by acids from cariogenic bacteria
What do you do use resin infiltrants on?
✓ Pre-eruptive enamel defects:
Molar-Incisor
Hypomineralization (MIH)
Fluorosis
Post-traumatic hypomineralization
✓ White spot lesions
✓ Proximal noncavitated enamel lesions
What causes the visual effect in white spot lesions?
Differences between refractive index (RI) in sound and white spot lesion in enamel (WSL)
What are the objectives of resin infiltration technique?
✓ Replacing air into the hollow spaces in WSL with a low-viscosity light-cured resin with a RI (1.52) similar to that of hydroxyapatite
✓ To mask the WSL by preventing the light scattering inside the WSL.
What are the steps of resin infiltration technique?
- Acid etching (15% HCl) Create “access” to the porous areas of the enamel through corrosion to allow resin penetration
- Drying the surface (alcohol) Removing water, allowing the resin infiltration
- Resin infiltration To replace the air by resin into the porous structure
- Light cure the resin
What layer of the tooth has resin infiltration been demonstrated to be effective?
into 1/3 of the dentin
What are the pieces for resin infiltration?
- Etchant (Icon-Etch; DMG): 15% hydrochloric acid, water, pyrogenic silica, surfactant, pigment
- Drier (Icon-Dry; DMG): ethanol
- Resin infiltrant (Icon-Infiltrant; DMG): TEGDMA-based resin, initiators and stabilizers
____________ is the most prevalent disease in the world
Dental caries
_____________________ foremost reason for resin-based restoration failure and life span reduction
Secondary caries (recurrent caries)
Where are the areas with the highest prevalence for recurrent caries?
Gingival margin in Class II and V (plaque accumulation and deficient adaptation of restorative material)
What is the current dental restorative perspective about bioactivity?
anticaries approaches at the material level
What are the roles of the combinatory/multimodal bioactive materials?
- antimicrobial
- tissue regeneration
- remineralization
- enhanced bioactivity
What are some commercially available bioactive adhesive materials?
Clearfil SE Protect Bond (Kuraray) – Adhesive system
*MDP/MDP-B (monomer)
*Bactericidal mechanism
*Fluor release
What are some commercially available bioactive restorative materials?
- Activa (Pulpdent)
- Cention N (Ivoclar Vivadent)
- Re-gen (Vista Apex)
- Surefil one (Dentsply Sirona)
What does activa (pulpdent) do?
✓ Different shades
✓ Ionic Resin technology
✓ Preservation of the pulp vitality
✓ Release calcium, phosphate and fluoride
What does cention N (ivoclar vivadent) do?
✓ Different shades, light-curable or not, used in association with adhesive systems
✓ Alkasite material
✓ Fillers: barium aluminum silicate glass, ytterbium trifluoride, isofiller, calcium barium aluminum fluorosilicate glass
✓ Higher fluoride release and mechanical properties compared to RMGIs (in some studies)
✓ Several studies IN VITRO
What is re-gen (vista apex)?
✓ Flowable composite liner
✓ Bulk fill
What is surefill one (dentsply sirona)?
✓ Self-Adhesive
✓ Bulk fill Composite Hybrid
✓ Dual-Cure Activators
What are teh overall characteristics of commercially available bioactive restorative materials?
✓ Characteristics between GIs and composite resin (CRs)
✓ Higher mechanical properties than GIs
✓ Lower properties compared to CRs
✓ Release calcium, phosphate and fluoride
✓ Same indications of RMGIs
✓ Long-term efficacy and bond strength require further investigations
✓ Limited evidence in terms of clinical effectiveness
Bioactive materials are designed to elicit a desired what kind of response?
therapeutic or
beneficial response
What does the term bioactive mean?
indiscriminately applied to include all simple chemistry, and most effects are indirect results from biological defensive response
