24 Questions
What is the fabrication method of semi precision attachment?
All of the above
What is the function of the mortise in precision attachment?
To act as a keyway for the female component
What is the contraindication for non-rigid connector if the abutment presents?
Significant mobility
What is the benefit of using non-rigid connector in terms of esthetics?
Improved esthetics with porcelain
What is the purpose of the occlusal rest in fixed supported bridges?
To rest on a class II inlay or full coverage restoration
What is the prerequisite for using a non-rigid connector?
Abutment preparation with conservative reduction
What is the potential risk of using a non-rigid connector?
Probability of key unseating from keyway
What is the limitation of using a non-rigid connector if the span between the abutments is longer than one tooth?
Stresses transferred to the abutment tooth would be destructive
What is the primary function of a nonrigid connector in a fixed partial denture?
To decrease the forces on the connector
When is a nonrigid connector typically used in a fixed partial denture?
When the abutments are not parallel and require an attachment for independent seating of the crown and/or bridge
What is the advantage of using a nonrigid connector when the prognosis of the distal abutment is questionable?
It solves the problem of repeating restoration of remaining abutments
What is the classification of precision attachments based on their fabrication method?
Precision and semi-precision
What is the characteristic of precision attachments that provides retention?
The frictional fit between the components
What is the primary advantage of using a precision attachment in a fixed partial denture?
It exhibits high surface adaptation and frictional fit
What is the classification of attachments based on their relationship to the abutment teeth?
Intra-coronal and extra-coronal
What is the primary indication for using a nonrigid connector in a fixed partial denture?
When joining implants with natural teeth
What is the main disadvantage of directing occlusal forces along the long axis of the abutment?
Excessive removal of tooth structure
What is the primary challenge in maintaining oral hygiene around extra-coronal attachments?
Difficult access to retainer contours
What is the purpose of soldering in dentistry?
To join similar or dissimilar metals
What is the minimum requirement for the size of a retainer in terms of distortion or fracture?
Large enough to prevent distortion or fracture
What is the recommended shape of the proximal attachment in terms of retainer design?
Circular or elliptical
What is the primary advantage of directing occlusal forces along the long axis of the abutment?
Occlusal forces directed along the long axis of the abutment
What is the primary concern during the process of soldering in dentistry?
Temperature control above 450°C
What is the purpose of using sectioned models in dentistry?
To increase the chance of inaccuracy
Study Notes
Types of Attachments
- Laboratory made types (Semi precision attachment): fabricated by direct casting of plastic, wax, or refractory patterns, incorporated with hand-waxed inserts, invested, eliminated, and casted in metal.
- Prefabricated types (Precision attachment): consist of precision-milled male-female assembly, fabricated in metal using high precision manufacturing technique.
Characteristics of Semi-precision Attachment
- Gently tapering walls for ease of fabrication.
- Less intimate fit between male and female components.
Characteristics of Precision Attachment
- Long, parallel walls and high surface adaptation.
- High frictional fit between highly fitting components.
- Main advantage: occlusal forces are directed along the long axis of the abutment.
- Disadvantages: excessive removal of tooth structure, non-resilient attachments.
Classification of Attachments
- Based on method of fabrication and tolerance of fit: Precision and Semi-precision attachments.
- Based on relationship to the abutment teeth: Intra-coronal (Internal attachment) and Extra-coronal (External attachment).
Non-rigid Connectors
- Acts as a stress breaker between retainer and pontic to decrease the forces on the connector.
- Used when abutments are not parallel and require an attachment for independent seating of the crown and/or bridge.
- Indications: joining implants with natural teeth, reduction of forces, questionable prognosis of the distal abutment, short edentulous span, and inlay presence.
Contraindications for Non-rigid Connectors
- Abutment presents significant mobility.
- Span between the abutments is longer than one tooth.
- Posterior retainer and pontic are opposed by a removable partial denture or an edentulous ridge.
Soldering
- Process of joining two similar or dissimilar metals or alloys by melting and flowing an intermediate metal alloy between and around the adjacent heated but unfused parts.
- Used in: construction of long span FPD, joining components of long span fixed partial denture, building up proximal contacts, and repairing casting voids or broken joints.
Requirements for Soldering
- Large enough to prevent distortion or fracture during function.
- Completely concave in peripheral attachment.
- Not blocking the embrasures or interproximal space.
- Circular or elliptical in proximal view.
- Centralized by the contact area.
This quiz covers the fabrication of semi-precision attachments in dental laboratory procedures, including direct casting of plastic, wax, or refractory patterns and the use of hand waxed inserts and tapered metal mandrels.
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