Podcast
Questions and Answers
What is a significant issue commonly associated with polymerisation in composite resins?
What is a significant issue commonly associated with polymerisation in composite resins?
Which type of resins is noted for being the most commonly used in composite restorations?
Which type of resins is noted for being the most commonly used in composite restorations?
What primary characteristic distinguishes ORMOCER® resins from acrylic resins?
What primary characteristic distinguishes ORMOCER® resins from acrylic resins?
Which additive is used to control viscosity in ORMOCER® resins?
Which additive is used to control viscosity in ORMOCER® resins?
Signup and view all the answers
Which of the following types of resins is developed primarily to minimize polymerisation shrinkage?
Which of the following types of resins is developed primarily to minimize polymerisation shrinkage?
Signup and view all the answers
What polymerisation method is commonly initiated by blue light in dental composite materials?
What polymerisation method is commonly initiated by blue light in dental composite materials?
Signup and view all the answers
What is the role of filler particles in composite resins?
What is the role of filler particles in composite resins?
Signup and view all the answers
Which monomers are commonly blended into acrylic resins to improve their flowability?
Which monomers are commonly blended into acrylic resins to improve their flowability?
Signup and view all the answers
What is the polymerisation shrinkage percentage of silorane-based resins compared to acrylic-based composites?
What is the polymerisation shrinkage percentage of silorane-based resins compared to acrylic-based composites?
Signup and view all the answers
Which type of polymerisation occurs with silorane-based resins?
Which type of polymerisation occurs with silorane-based resins?
Signup and view all the answers
Which of the following factors does NOT influence the stress of silorane-based resins during polymerisation?
Which of the following factors does NOT influence the stress of silorane-based resins during polymerisation?
Signup and view all the answers
What is a significant advantage of ring-opening polymerisation in silorane-based resins?
What is a significant advantage of ring-opening polymerisation in silorane-based resins?
Signup and view all the answers
Which of the following statements about ORMOCER® resins is FALSE?
Which of the following statements about ORMOCER® resins is FALSE?
Signup and view all the answers
Which polymerisation process is characterized by low shrinkage and is light-initiated in silorane-based resins?
Which polymerisation process is characterized by low shrinkage and is light-initiated in silorane-based resins?
Signup and view all the answers
What is one reason silorane-based resins are less frequently used in clinical practice compared to acrylic resins?
What is one reason silorane-based resins are less frequently used in clinical practice compared to acrylic resins?
Signup and view all the answers
Which property is mainly associated with acrylic-based composites that has been improved in modern formulations?
Which property is mainly associated with acrylic-based composites that has been improved in modern formulations?
Signup and view all the answers
What is the primary result of polymerisation shrinkage during the formation of a polymer?
What is the primary result of polymerisation shrinkage during the formation of a polymer?
Signup and view all the answers
Which type of polymerisation primarily occurs in the curing of dental polymers?
Which type of polymerisation primarily occurs in the curing of dental polymers?
Signup and view all the answers
What is the effect of increasing the degree of conversion (DC) on polymerisation shrinkage?
What is the effect of increasing the degree of conversion (DC) on polymerisation shrinkage?
Signup and view all the answers
Which component is primarily responsible for the shaping and adaptation of dental composites before hardening?
Which component is primarily responsible for the shaping and adaptation of dental composites before hardening?
Signup and view all the answers
Which of the following monomers is most commonly used in the formulation of dental composite resins?
Which of the following monomers is most commonly used in the formulation of dental composite resins?
Signup and view all the answers
What is a key characteristic of dimethacrylate-based resins after curing?
What is a key characteristic of dimethacrylate-based resins after curing?
Signup and view all the answers
What role do flexible low molecular weight monomers play in the formulation of dental composites?
What role do flexible low molecular weight monomers play in the formulation of dental composites?
Signup and view all the answers
Which of the following monomers possesses a more flexible backbone compared to bis-GMA?
Which of the following monomers possesses a more flexible backbone compared to bis-GMA?
Signup and view all the answers
What is a common property observed in high molecular weight resin components?
What is a common property observed in high molecular weight resin components?
Signup and view all the answers
Which type of polymer is specifically noted for having lower polymerisation shrinkage than traditional methacrylate-based resins?
Which type of polymer is specifically noted for having lower polymerisation shrinkage than traditional methacrylate-based resins?
Signup and view all the answers
Study Notes
Non-Acrylic Resins
- ORMOCER® resins are inorganic-organic copolymers, combining reactive organic species with a siloxane network.
- Polymerisation occurs through addition reactions, allowing for low shrinkage and superior aesthetics.
- TEGDMA serves as a viscosity controller, balancing the viscosity similar to bis-GMA.
- Filler particles are necessary to enhance strength in ORMOCER composites.
Dental Composite Resins
- Organic resin enables flow and shaping within cavities until polymerisation.
- Blue light facilitates free radical polymerisation, turning composite resin into a rigid solid.
- Common dimethacrylate monomers include bis-GMA, UDMA, TEGDMA, and bis-EMA.
- Larger, rigid monomers in resins increase viscosity; flexible, low molecular weight monomers improve flowability.
- Modified dimethacrylate monomers have been created to minimize polymerisation shrinkage and stress.
Polymer Science
- Polymers are large macromolecules formed by repeating covalent links of monomers.
- Characteristic properties are influenced by the chemical structure, including the types of monomers and their organization.
- Addition polymerisation (chain-growth) and condensation polymerisation (step-growth) are the two main reaction types.
- Polymerisation shrinkage results in volume reduction and internal contraction stress, exacerbated by higher degrees of conversion and lower molecular weight monomers.
Silorane-Based Resins
- Silorane monomers undergo ring-opening polymerisation, which reduces volumetric shrinkage to less than 1%.
- Utilizes light-initiated and cationic polymerisation, eliminating unreacted layers that can trap oxygen.
- Comparable strength to acrylic resins, but less frequently used due to advancements in stress-reducing acrylics.
ORMOCER® Resins
- Stand for ORganically MOdified CERamic, functioning as "all-ceramic direct fillings."
- Designed to minimize issues like microleakage and secondary caries, hence no traditional monomers are present.
Resin Matrix in Dental Composites
- The resin matrix surrounds filler particles and is a fluid mixture of monomers that harden upon activation.
- Dimethacrylate-based resins dominate, providing the chemically active component for shaping before curing.
Acrylic Resins Chemistry
- Difunctional monomers in acrylic resins can link with multiple other monomers forming crosslinked structures during curing.
- Crosslinking increases molecular weight and rigidity, enhancing wear resistance but also limiting polymerisation.
Commonly Used Monomers
- Bis-GMA is the primary monomer due to its high viscosity and strength, necessitating blending with other monomers for workability.
- EGDMA and TEGDMA, flexible low molecular weight monomers, are incorporated to reduce viscosity and improve handling, though they contribute to higher shrinkage.
- Current formulations often include UDMA and bis-EMA, which offer similar strength with better flow properties due to their molecular structure.
Desired Properties of Dental Composite Resins
- Focus on achieving low shrinkage, adequate strength, optimal flowability, and resistance to wear.
- Aim for minimal microleakage and high aesthetic quality in restorative applications.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
