Intro to Direct and Indirect Restorations Flashcards
What are the basic principles of a restoration?
- Retention of the material with the tooth structure (within harsh environment)
- Ability to maintain function and protect from further mechanical failure (needs to maintain function of original tooth)
- Prevent formation of recurrent caries
- Perform under occlusal load
- Aesthetics
What do we need to think about when selecting a material?
Analyse problems, think of requirements for that resotation based on location, think of available materials
What 3 things vary significantly in the oral environment?
- Temp (due to food taken in, exposure of environment to these temp, changes are transient and large) usually between 32-37 but hot drink can go up to 56
- pH (due to what is eaten, difference in individuals)
- Cyclic stresses (have to pick which material based on compressive and tensile forces)
What can materials replace?
Can replace lost or damaged tooth tissue. They are used to maintain or improve quality of life through replacement or alteration of tooth structure.
What are the main types of material?
Temporary, intermediate and permanent.
Direct and indirect.
What are some details on direct restorations?
All such procedures involve chairside treatment.
The materials must adhere to the tooth structure and be able to flow. The materials must be set in a desired time post placement in the oral environment.
The need for restoration may arise due to trauma, dental caries, abrasion or dietary habits.
Restoration may vary in size, shape and location in the mouth - choice of material is governed by this.
Some materials may set in a moist environment and other may not.
What are some details of indirect restorations?
Procedures carried out in the dental laboratory.
Fabrication can be done at a higher temperatures and or high pressure.
It is essential that these fixtures are then bonded to the tooth structure.
Indirect - carried out in lab, fixture are made in the lab but instructions are given by clinician.
Material will be prepared as for requirement under specific conditions
What are the requirements for direct filling materials?
- Durability of a restoration governs the success of a restorative material
- Durability depends on: physical, mechanical and biological properties
Any material should not undergo any changes due to these factors.
What are the 3 main requirements for dental materials in general?
- Stable in the oral environment
- Withstand masticatory forces
- Aesthetics
Give some differences in properties between permanent and temporary fillings
Permanent:
- Biocompatible
- Adequate strength for mechanical function and durable over a long period of time
- Bond permanently to tooth structure
- Match the natural appearance of tooth structure and other visible tissues
- Exhibit properties similar to those of tooth tissues (enamel and dentine)
- Initiate tissue repair or regeneration of missing or damaged tissues
Temporary:
- Biocompatible
- Adequate strength to last a few weeks, but weak enough to be dislodged easily
- Easy to place and remove
- Provide adequate sealing
- Possess antibacterial properties
- Therapeutic effects such as pain relief, healing.
- Cariostatic properties
What are the 4 main types of material in dentistry?
- Glasses
- Composites
- Metals
- Porcelain and resin
What properties of materials do we use to characterise them?
- Storage
- Setting
- Mixing
- Properties of material
What do we need to be away of during mixing and setting?
- Method of dispensation (mixing of pastes, automixing)
- Rate of set (working and setting time)
- Viscosity (flow properties)
- Temp rise on setting
- Dimensional changes
(If setting time Is too long, the material can deform and the patient will have their mouth open for a long time. Should set quickly.
Viscosity affects flow, too viscous = difficult to place, little viscosity = splashing everywhere.
Material undergo reactions when setting = temperature increase, leads to the temperature increase in pulp or soft tissue which causes damage.
Can undergo changes in dimension, may expand or shrink.)
What do we need to be aware of with set material?
- Mechanical properties
- Physical properties
- Thermal properties
- Chemical properties
- Biological properties
- Adhesion
(Physical - interacting with oral environment, changes when subjected to oral fluids
Thermal - expand/contact with temp change
Chemical - what happens when interaction with oral fluids, any reactions occurring
Biological - compatible with tissues, no release of chemicals that could be toxic
Adhesion - for retention of the material)
What are the ideal requirements for chemical and thermal properties?
Chemical - filling material should be resistant to the hostile oral environment and withstand dissolution, degradation and erosion
Thermal - filling materials should be good insulators protecting the pulp from hot/cold. They should ideally match the thermal expansion/contraction of enamel and dentine.
