Final answer:
The features of onlay preparation include the preservation of tooth structure, achieving marginal integrity, ensuring retention and resistance form, providing proper occlusal clearance, attaining proper taper of the walls, and finessing finish lines for a precise fit of the onlay.
Step-by-step explanation:
The features of onlay preparation in dentistry involve preparing a tooth for receiving a custom-made restoration that fits within the contours of the tooth. Key elements include:
- Preservation of tooth structure: Onlays allow for more conservation of the natural tooth compared to crowns because less tooth material needs to be removed.
- Retention and resistance form: The preparation must provide sufficient retention to prevent dislodgment of the onlay from chewing forces, and resistance form to prevent dislodgment from lateral or oblique forces.
- Marginal integrity: The margins of the preparation must be precisely defined so that the onlay can fit seamlessly, preventing plaque accumulation and secondary caries.
- Proper occlusal clearance: There must be sufficient space for the restorative material to withstand occlusal forces without fracture.
- Proper taper of the walls: Adequate tapering of the cavity walls is necessary for the onlay to sit properly on the tooth and for ease of fabrication.
- Finessed finish lines: The finish lines of the preparation should be smooth to ensure a proper fit and finish of the onlay.
Ultimately, the onlay preparation should follow the principles of conservative dentistry while providing a strong foundation for the onlay to restore the tooth's function and aesthetics.