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Questions and Answers
What is the primary purpose of resistance form in cavity preparation?
What is the primary purpose of resistance form in cavity preparation?
- To remove unsupported enamel to prevent fracture
- To restrict the extension of the walls for strong cusp and ridge support
- To shape the cavity walls to withstand the force of mastication without fracture (correct)
- To create a smooth pulpal floor to resist restoration movement
Why should the pulpal floor be flat and perpendicular to the long axis in cavity preparation?
Why should the pulpal floor be flat and perpendicular to the long axis in cavity preparation?
- To allow for easy removal of unsupported enamel
- To reduce stress concentration at internal line angles
- To resist restoration movement and prevent wedging action on the tooth (correct)
- To prevent the spread of caries in dentin
What is the significance of slightly curved (rounded) internal line angles in cavity preparation?
What is the significance of slightly curved (rounded) internal line angles in cavity preparation?
- To restrict the extension of the walls for strong cusp and ridge support
- To reduce the spread of caries in dentin
- To allow for easy removal of unsupported enamel
- To prevent stress concentration and fracture of tooth structure (correct)
Why should unsupported enamel be removed during cavity preparation?
Why should unsupported enamel be removed during cavity preparation?
What should be restricted by controlling the width of the cavity in cavity preparation?
What should be restricted by controlling the width of the cavity in cavity preparation?
What is the typical depth of the cavity when caries is present in the pulpal floor or axial wall or both?
What is the typical depth of the cavity when caries is present in the pulpal floor or axial wall or both?
What instrument should be used to remove caries when present in the pulpal floor or axial wall or both?
What instrument should be used to remove caries when present in the pulpal floor or axial wall or both?
How can caries dentin be detected?
How can caries dentin be detected?
What can result from removing all of the pulpal floor due to caries?
What can result from removing all of the pulpal floor due to caries?
What are the objectives of finishing the cavity walls?
What are the objectives of finishing the cavity walls?
What factors must be considered in the finishing of enamel walls and margins?
What factors must be considered in the finishing of enamel walls and margins?
What is the purpose of toilet of the cavity?
What is the purpose of toilet of the cavity?
How should toilet of the cavity be performed?
How should toilet of the cavity be performed?
What should be used to detect caries dentin?
What should be used to detect caries dentin?
What is the result of removing all pulpal floor?
What is the result of removing all pulpal floor?
What should be used to remove caries when present in pulpal floor or axial wall?
What should be used to remove caries when present in pulpal floor or axial wall?
What must be considered in finishing enamel walls and margins?
What must be considered in finishing enamel walls and margins?
What is the aim of the retention form in restorative dentistry?
What is the aim of the retention form in restorative dentistry?
Why should the width of the cavity be 1/4 of the intercuspal distance?
Why should the width of the cavity be 1/4 of the intercuspal distance?
What is the purpose of a smooth pulpal floor in cavity preparation?
What is the purpose of a smooth pulpal floor in cavity preparation?
Why should the mesial and distal walls of the cavity be made parallel or slightly diverge?
Why should the mesial and distal walls of the cavity be made parallel or slightly diverge?
What is the minimum thickness of amalgam required to withstand the load applied without being fractured?
What is the minimum thickness of amalgam required to withstand the load applied without being fractured?
What is the purpose of box form in cavity preparation?
What is the purpose of box form in cavity preparation?
What is the aim of convenience form in restorative dentistry?
What is the aim of convenience form in restorative dentistry?
What is the recent trend in conservative restorative dentistry regarding retention?
What is the recent trend in conservative restorative dentistry regarding retention?
What is the function of an axial groove in restorative dentistry?
What is the function of an axial groove in restorative dentistry?
What is the purpose of reverse bevel in gold inlays?
What is the purpose of reverse bevel in gold inlays?
Why should convergence of buccal and lingual (palatal) walls be about 50 degrees?
Why should convergence of buccal and lingual (palatal) walls be about 50 degrees?
What is the advantage of reducing dependence on mechanical interlocking for retention?
What is the advantage of reducing dependence on mechanical interlocking for retention?
Study Notes
Cavity Preparation
- Primary purpose of resistance form is to prevent fracture of tooth structure.
- Pulpal floor should be flat and perpendicular to the long axis to allow for even distribution of stress and reduce the risk of fracture.
Cavity Design
- Slightly curved (rounded) internal line angles help to reduce stress concentrations and prevent fracture.
- Unsupported enamel should be removed to prevent fracture and ensure structural integrity.
Width and Depth of Cavity
- Width of cavity should be restricted to 1/4 of the intercuspal distance to prevent excessive removal of tooth structure.
- Typical depth of cavity when caries is present in pulpal floor or axial wall is 0.5-1.5 mm.
Caries Removal
- Caries dentin can be detected using a caries detector dye.
- Excavators or round burs should be used to remove caries when present in pulpal floor or axial wall.
Finishing the Cavity
- Objectives of finishing the cavity walls are to provide a smooth surface, remove any sharp edges, and ensure a tight seal.
- Factors to consider when finishing enamel walls and margins include beveling, smoothing, and polishing.
Toilet of the Cavity
- Purpose of toilet of the cavity is to remove any debris or residue, ensuring a clean surface for restoration.
- Toilet of the cavity should be performed using a soap and water followed by an alcohol rinse.
Retention Form
- Aim of retention form is to provide mechanical interlocking between the tooth and the restoration.
- Width of the cavity is restricted to allow for adequate retention without excessive removal of tooth structure.
Other Considerations
- Smooth pulpal floor helps to reduce stress concentrations and prevent fracture.
- Mesial and distal walls of the cavity should be made parallel or slightly divergent to allow for even distribution of stress.
- Minimum thickness of amalgam required to withstand the load applied without being fractured is 1.5 mm.
- Box form provides additional retention through mechanical interlocking.
- Convenience form provides easy access for restoration placement and removal.
Trends in Restorative Dentistry
- Recent trend in conservative restorative dentistry is to reduce dependence on mechanical interlocking for retention.
- Axial groove serves as a guide for the placement and removal of the restoration.
- Reverse bevel in gold inlays helps to increase the strength of the restoration.
- Convergence of buccal and lingual (palatal) walls should be about 50 degrees to allow for easy removal of the restoration.
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Description
Learn about the resistance form and the shaping and placement of cavity walls to withstand mastication force. Understand the importance of a flat pulpal floor in preventing restoration movement and tooth fracture.
