Which is an example of a direct restorative dental material for a class I restoration?

Recommended textbook solutions

Pharmacology and the Nursing Process

7th EditionJulie S Snyder, Linda Lilley, Shelly Collins

388 solutions

Clinical Reasoning Cases in Nursing

7th EditionJulie S Snyder, Mariann M Harding

2,512 solutions

Exercise Physiology: Theory and Application to Fitness and Performance

11th EditionEdward Howley, John Quindry, Scott Powers

593 solutions

Health: The Basics

11th EditionRebecca J. Donatelle

249 solutions

Recommended textbook solutions

Pharmacology and the Nursing Process

7th EditionJulie S Snyder, Linda Lilley, Shelly Collins

388 solutions

Clinical Reasoning Cases in Nursing

7th EditionJulie S Snyder, Mariann M Harding

2,512 solutions

Brunner and Suddarth's Textbook of Medical-Surgical Nursing

14th EditionJanice L Hinkle, Kerry H Cheever

440 solutions

Medical Assisting: Clinical Procedures

7th EditionKathryn A Booth, Leesa Whicker, Terri D Wyman

861 solutions

Generally made up of an organic polymerizable resin matrix, inorganic filler material and a coupling agent,1, 4-6 resin composite restorative materials were developed as an esthetic alternative to amalgam by providing a tooth-colored filling. Durability, strength, and cost issues have prevented composites from entirely replacing the need for amalgam fillings, despite efforts to scale-back the use of mercury-based amalgam driven largely by environmental concerns. Many resin materials need to be light-cured, and adhesion to tooth structure requires “intermediary agents containing highly reactive chemicals”7 as well as relatively expensive curing devices which require protective equipment.4

Composites are a heterogeneous group and are often classified by resin type, particle filler size or curing type,4, 8, 9 although these classifications are nonexclusive and often overlap.4 The evolution of resin composite materials has involved modifications in curing type, filler particles, and resin composition.5 Increased depth of cure and reduction of shrinkage and curing time have driven contemporary research in composite technology.4, 10, 11

Resin Matrix

Highly-viscous bisphenol A glycidyl methacrylate (BisGMA) began to be incorporated as a matrix following its patenting in the early 1960s,10 and urethane dimethacrylate in the 1970s,4, 12 while other monomers (such as triethylene glycol methacrylate, or TEGDMA) were eventually added to reduce the viscosity and allow easier manipulation and a wider variety of filler materials.4, 8, 12, 13 Methacrylate polymerization naturally results in shrinkage5 and thus may lead to marginal gaps and weakening of the bond between the composite and the tooth structure.4, 11 More recently, alternatives to methacrylate-based resins have been developed to avoid polymerization shrinkage, including the replacement of TEGDMA with BisEMA,14 and an epoxy known as silorane (from the combination of siloxane and oxirane) has been introduced by 3M ESPE.6, 15, 16

Filler Particle Classifications

In the 1950s, silica was introduced as a filler to polymer matrix composites as a reinforcing material, although issues with shrinkage and bonding persisted.8, 17 Polishability and wear-resistance were problems with “traditional” or macro-filled composites throughout the 1970s, when mid-and micro-filled composites began to appear.4, 18 Micro-fillers (containing particles between 0.01 and 0.1 µm4, 9, 18) were developed for better polishability but the lower filler load resulted in weak mechanical properties,5 until hybrids were developed in the in the 1980s, which combined macro- with micro-fillers allowing better mechanical properties along with polishablitiy.4, 5, 18 and nano-fillers (5-10 nm)7 in the 2000s.5, 18 Hybrids contain both nanoparticles (1 to 100 nm)7 and microparticles (≤1 µm), allowing a highly polished surface and gloss.4, 19

Composites are traditionally incrementally filled (in stages of around 2mm), but bulk fill composites have allowed a single-step fill of 4mm or more.6 Bulk filled composites eliminate a step and provide an alternative to amalgam fillings,20 although according to this ADA ACE Panel Report, among responding dentists,
the incremental technique is preferred for posterior composite restorations, who tend to be concerned with inadequate cure of depth and polymerization shrinkage.

Composites can further be classified according to filler density. Decreasing the density of the fill results in lower viscosity and improvement in manipulation characteristics including ease and uniformity of flow and adaptation to cavity structure; these flowable resins, however, have and increased susceptibility to wear and polymerization shrinkage compared to higher-density, or packable, composites.4, 12 Packable composites are suitable for large posterior restorations; flowable composites are typically used as a liner or base, or limited to low-stress-bearing posterior restorations.21

Curing type

Traditional composites were self-cured, meaning they required hand-mixing of the matrix and monomer along with the filler particles.4, 5 Light-curing was introduced in the 1970s, providing better predictability and stability of the preparation.5 Early light-curing required UV light which not only was a hazard to eyes and oral mucosa, but also only provided a shallow depth of cure for the composite.5 A safer and more effective alternative to UV-cured composites was developed by the late 1970s, utilizing visible light on a camphorquinone initiator.4, 5

Light curing, however, still has limitations on light penetration, and light-cured composites must be placed incrementally when they exceed a depth of around 2 mm.4Dual-cure resins have been developed for deeper applications where light penetration may be limited, and combines light-curing with the chemical reaction between benzoyl peroxide and an aromatic tertiary amine, resulting in more rapid polymeriztion.4, 10

Properties of Resin Composites

ADA Specification No.27 stipulates requirements for resin-based filling materials, and includes standards and testing requirements, with shade, color stability, flexural strength, and radiopacity among them.22, 23 Table 2, below, lists common properties of types of composite resin materials.

Table 2. Some properties of Composite Materials.4, 6

Which is an example of a direct restorative dental procedure?

What is a Class 1 restoration?

Which restorative material is selected for the permanent restoration of a Class 1 lesion?

How many tooth surfaces does Class I restoration involve?