Questions and Answers
When preparing the outline form of the Class IV direct composite preparation, what is removed?
Weakened, friable enamel
What primarily dictates the extensions of the Class IV direct composite preparation?
The extent of the caries lesion, fracture, or failed restoration
What is the primary purpose of bevel placement on accessible enamel margins in Class IV tooth preparation?
To mask the restoration margin
What is the recommended angle for preparing the bevel on accessible enamel margins?
Signup and view all the answers
What is the primary mechanism of retention for most Class IV direct composite restorations?
Signup and view all the answers
In what situation may additional mechanical retention be obtained through groove-shaped or other forms of undercuts?
Signup and view all the answers
What is the recommended depth for preparing the gingival retention groove?
Signup and view all the answers
In which area of the tooth is a retentive undercut usually not needed?
Signup and view all the answers
What is the primary objective of the initial tooth preparation in conservative tooth preparation?
Signup and view all the answers
What is the typical axial wall depth of Class III preparations in primary caries?
Signup and view all the answers
Why is an enamel bevel sometimes incorporated into the tooth preparation?
Signup and view all the answers
What is the recommendation for undermined enamel in nonocclusal stress areas?
Signup and view all the answers
What is the approach to preparing the tooth walls perpendicular to the enamel surface?
Signup and view all the answers
What is the goal of the initial tooth preparation in terms of dentinal support?
Signup and view all the answers
What is the primary consideration when deciding on the extension of the outline form?
Signup and view all the answers
What is the characteristic of the axial preparation walls in conservative tooth preparation?
Signup and view all the answers
What is the primary objective of Class V tooth preparation for small or moderate lesions or defects?
Signup and view all the answers
What is the recommended approach for preparing the enamel margin in Class V tooth preparations?
Signup and view all the answers
In areas with hypermineralized (sclerotic) dentin, what is required for successful bonding?
Signup and view all the answers
What is the recommended tool for removing carious tissue in dentin during Class V tooth preparation?
Signup and view all the answers
What is the purpose of extending the preparation into dentin during Class V tooth preparation?
Signup and view all the answers
What type of tooth defects are ideal for small Class V tooth preparations?
Signup and view all the answers
Why are enamel bevels not typically used on the cervical margin of the preparation?
Signup and view all the answers
What is the result of the Class V tooth preparation technique on the axial surface?
Signup and view all the answers
Study Notes
Class IV Direct Composite Preparation
- The extension of the preparation is determined by the extent of the caries lesion, fracture, or failed restoration being replaced.
- The outline form is prepared to include weakened, friable enamel, and all weakened enamel is removed.
- The initial axial wall depth is established, and the preparation is done at high speed with air-water coolant.
Key Steps in Preparation
- Selective carious tissue removal (if present)
- Pulp protection (if needed)
- Bevel placement on accessible enamel margins
- Final procedures of cleaning and inspecting
Beveling
- Bevels are prepared at a 45-degree angle to the external tooth surface with a lame-shaped or round diamond instrument.
- The width of the bevel should be 0.5 to 2 mm, depending on the amount of tooth structure missing and the retention needed.
- A scalloped, nonlinear bevel can be used to mask the restoration margin.
Retention
- Retention is provided primarily by bonding of the composite to enamel and dentin.
- Additional mechanical retention may be obtained by groove-shaped or other forms of undercuts, dovetail extensions, or a combination of these.
- A gingival retention groove is prepared using a round bur, 0.2 mm inside the DEJ at a depth of 0.25 mm.
Preparation Walls
- No effort is made to prepare walls that are perpendicular to the enamel surface.
- For small preparations, the walls may diverge externally from the axial depth, resulting in a beveled marginal design.
- For larger preparations, the preparation walls may not be as divergent from the axial wall.
Objective of Initial Tooth Preparation
- The objective is to prepare the tooth as conservatively as possible by extending the outline form just enough to include the peripheral extent of the lesion.
- The extension should be minimal, including only the tooth structure that is compromised by the extent of the caries lesion or defect.
Class V Tooth Preparation
- The objective is to restore the lesion or defect as conservatively as possible.
- No effort is made to prepare the walls as butt joints, and usually no secondary retentive features are incorporated.
- The lesion or defect is conservatively prepared, resulting in a form that may have a divergent wall configuration and an axial surface that usually is not uniform in depth.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
