Composite Resins: Types, Composition & Characteristics

Composite Resin

• Belongs to the 5th lecture, the topic focuses on composite resins, their types, composition, and different characteristics

Table of Contents

• Introduction is found on Page 2
• Composite composition is found on Page 5
• Composite classification is found on Page 15
• Traits that should be available in composite are found on Page 30
• Clinical application of composite are found on Page 37
• Repair of composite restorations are found on Page 46

Introduction

• Dental restorative materials have evolved over time
• There is a pursuit of the ideal material that provides good esthetics and high resistance to various stresses
• Composite stands out as a result of the development of esthetic materials
• Composite is known for it's high aesthetic qualities
• Work has been done to improve the durability of the material inside the prepared cavity and increase its resistance to occlusal forces
• Work has been done to secure a strong bond with the tooth structure

Composite Material Timeline

• 1904: Silicates were developed as the first esthetic resin cement by Sleinbock, but not widely used due to leakage and harm to pulp
• 1943: Self-curing unfilled dental resins were developed by Kultzer, but they were soft and not resistant to pressure
• 1959: The first filled acrylic resin known as Bis-GMA appeared by Bowen
• 1962: The first resin with glass filler particles appeared
• Acid etching evolved in 1970 with 35-37% phosphoric acid, creating mechanical micro-retention between the restorative material and tooth surface
• Composite resins that harden by light appeared in 1970, depending on ultraviolet rays to harden eg Light-Cured Composite
• 1972: These resins evolved to depend on white visible light to harden
• 1975: Glass Ionomer Cement (GIC) appeared, discovered by Mclean and Wilson, and has been modified several times to improve it

Composite Composition

• Composite resins are composed of resin matrix, filler, and a coupling agent
• Resin matrix is composed of organic materials
• It does not vary much in it's formula compared to fillers
• It’s main responsibility involves setting shrinkage resulting from the formation of polymer chains

Composite Matrix Formulas

• Two main formulas are Urethane Di Metha Crylat (UDMA), and Bis-GMA

Bis-GMA

• Is found in most types of composite
• Bowen determined that it is made of two main materials: Bisphenol A, and Glycidyl methacrylate
• The equation for Bis-GMA is Bis phenol A + Glycidyl methacrylate ⇨ Bis-GMA

UDMA

• Is found in some types of composite
• Characterized by a resin matrix which has a high viscosity, while also being resistant to solvents, and easy to clean clinically

Composite Matrix Information

• Thri Ethelene Glycole Di metha Crylate (TEGDMA( has also appeared, but is not widely used
• The primary factor for setting shrinkage in composite is the resin matrix
• Fillers reduce setting shrinkage and improve mechanical properties

Filling Particles

• They are inorganic materials in glass crystal shape consisting of lithium, aluminum silicate, silicates, and quartz
• Provide radiopacity, containing heavy metals to absorb radiation like barium Ba, strontium Sr, and zirconium Zr
• Added atoms should have a high atomic weight like iodine

Filling Particles Note

• Radiopacity helps define the potential for recurrent decay (caries)

Filling Particle Roles

• Filling particles are important in composite restorations because they help the material to resist occlusal stresses clinically, taking on basic role to improve mechanical qualities of resin matrix which include
  • Wear Resistance
  • Tensile and compressive strength
  • Stiffness to the material
  • Low coefficient of thermal expansion for resin
  • Reduce polymerisation shrinkage of resin
  • Reduced water absorption of resin

Filling Particles Info

• By themselves, the particles tend to not be condensable in the prepared cavity
• When combined with the resin and bonding material, they give viscosity to the composite that allows it to reach all the prepared cavity details
• The amount of filling particles ranges between 70-80% volume

Filling Particles Size and Quality in Composites

• The composition of composite material is heavily influenced by the filling materials
• Composites with a higher percentage of filling materials have correspondingly less resin matrix
• Each composite can be catergorized by size, with nano being smallest to macro being largest

Contraction and Expansion

• Setting contraction depends significantly on the filler materials, where larger amounts of filler material relate to increased contraction in the resin matrix portion
• Quartz is present in traditional composite, a type of filler which is hard, difficult to finish, not radiopaque, but has good aesthetics, low aesthetics, and offers good bonding to the material
• Silica is in microfiller, the filling is very smooth, but also employs Silica Oxide and silicate barium, as well as pure types of colloids

Glassy Fillers

• Helpful in boosting radiopacity.
• Benefit scanning radiopacity.
• Composites are classified based on filler material composition
  • Ultra Low Fill with the composition being <50% filler with relatively weak resistance and good for regions not subject to high occlusal forces (66% weight)
  • Low Fill has 50 - 74% filler materials, strong, and helpful in regions where the restoration will come into contact with occlusive forces (75- 80% weight)
  • Compact has the composition being >75% filler, high resistance (Greater than 74% weight)
• Filler particle size varies between 1-10 microns, however the more recent attempts have worked to have them in as small a size as possible for optimized aesthetics

Small and Large Particles

• The increased bulk of volume corresponds to improved strength in the composite
• Smoother surfaces reduce wear and tear of teeth, so smaller particles will have better results from polishing and abrasion
• Large particles may be useful for increasing the size of the composite
• Smaller particles have greater beauty, emulate enamel, and are more translucent

Material Integration

• It is critically important to have diverse particles of filling material to increase material strength
• Small integrated particles help establish good bonding and reinforcement to the teeth

Matrix Binders

• The primary job is to promote linking of ingredients.
• Vinyl Silane bonds the materials that are resin based, which are non organic
• They make sure that the molecules involved form bonds
• 3-Methoxy Silane and Thri Methoxy compounds help integrate the parts

Binders vs Fillers

• Bonding, where one joins with the next

Composite Categories

• Size of granules

Type I - Traditional Composite

• Granules of 10-15 microns

Type II - Small Particle Composite

• Granules that range from 1-5 microns

Hybrids and Composites

• Have materials that fuse the elements together
• The mix contains hybrid composites of a wide array of materials

Nanocomposites

• Great aesthetic with 0.0.1-0.004 micron measurements

Filler Classification

• Chemically Activated
• Light Activated, which sets better and stronger, and comes in several materials
• Composites are found in two containers, which are placed into a dental syringe for injecting

Application

• Materials are applied in equal measure, mixed with an applicator, and pasted onto a paper for mixing.

Placement

• Once mixed, the composite is applied to an area and left to dry for 3 minutes

Considerations

• Chemical compounds should not be touched, or used with other materials

Light-Activated Composites

• Use a light curing technology, alpha di ketones

Dark vs Light

• When it comes to color, there is a need for longer lasting color
• Enamel requires longer curing
• Dual hardening fills in any gaps
• Single molecule composites bind together

Factors to Consider

• Shade: The most ideal factor should be esthetically pleasing
• Consistency
• Longevity
• Strong mechanical nature

Quality Considerations

• They can be rated from 5-10 years, depending on the patient and the work done

Considerations for Clinical Use

• Good Biocompatiility
• Acid etching may cause irritation
• Shrinkage
• Bond strength

Factors of Application

• Application of a rubber dam
• Cleaning of a site
• The base is set with water
• Dry the tooth

Filling Implementation Notes

• Bevel is only needed when there is a requirement for it
• Etch for some time

Important steps to restore:

• Avoid saliva
• Implement for 20-30s and then for cleaning, for enamel and dentin

Restoration

• The composition requires the right materials at the proper level

Quality Components

Important for the overall long-term results:

• Good shade
• Easy to work with

Restoration

• The teeth should be clean prior to repairs so they will bond

Components of Decay

• Bacteria can impact integrity of the parts
• Materials breakdown and the restoration requires repairs
• Composite with old components should be replaced

Explore composite resins as dental restorative materials, focusing on their evolution, aesthetic qualities, and durability. Learn about their composition, classification, and clinical applications. Understand the pursuit of the ideal material that balances aesthetics with resistance to stresses and strong bonding with tooth structure.