Podcast
Questions and Answers
What are the two main parts of an impression tray?
What are the two main parts of an impression tray?
What distinguishes stock trays for dentulous patients from those for edentulous patients?
What distinguishes stock trays for dentulous patients from those for edentulous patients?
What type of impression tray is used to make a final impression?
What type of impression tray is used to make a final impression?
Which material is NOT mentioned as being used to create stock trays?
Which material is NOT mentioned as being used to create stock trays?
Signup and view all the answers
A perforated stock tray is specifically used with which type of impression material?
A perforated stock tray is specifically used with which type of impression material?
Signup and view all the answers
Which feature of the handle in an impression tray is designed to avoid interference with the lip during procedures?
Which feature of the handle in an impression tray is designed to avoid interference with the lip during procedures?
Signup and view all the answers
Which tray type can be reused for multiple patients?
Which tray type can be reused for multiple patients?
Signup and view all the answers
What is the notable design difference between the upper tray and lower tray in impression making?
What is the notable design difference between the upper tray and lower tray in impression making?
Signup and view all the answers
What is the purpose of the four stoppers in the finger adapted dough method?
What is the purpose of the four stoppers in the finger adapted dough method?
Signup and view all the answers
Which step is crucial for the close fit special tray construction?
Which step is crucial for the close fit special tray construction?
Signup and view all the answers
What is the minimum thickness required for the tray in the sprinkle-on acrylic technique?
What is the minimum thickness required for the tray in the sprinkle-on acrylic technique?
Signup and view all the answers
Why should the impression tray borders be under-extended by 2 mm?
Why should the impression tray borders be under-extended by 2 mm?
Signup and view all the answers
During the sprinkle-on acrylic technique, what should be done just before the final polymerization?
During the sprinkle-on acrylic technique, what should be done just before the final polymerization?
Signup and view all the answers
What feature does the acrylic resin handle provide in a close fit special tray?
What feature does the acrylic resin handle provide in a close fit special tray?
Signup and view all the answers
What is the consequence of making the tray too thick?
What is the consequence of making the tray too thick?
Signup and view all the answers
What is the primary reason for using a non-perforated stock tray with alginate impression material?
What is the primary reason for using a non-perforated stock tray with alginate impression material?
Signup and view all the answers
What is the correct process for eliminating undercuts on the cast in the sprinkle-on acrylic technique?
What is the correct process for eliminating undercuts on the cast in the sprinkle-on acrylic technique?
Signup and view all the answers
Which factor is NOT relevant when selecting a stock tray for an impression?
Which factor is NOT relevant when selecting a stock tray for an impression?
Signup and view all the answers
What is a significant advantage of using a special tray over a stock tray?
What is a significant advantage of using a special tray over a stock tray?
Signup and view all the answers
Which material is most commonly used for constructing special trays?
Which material is most commonly used for constructing special trays?
Signup and view all the answers
Why are special trays considered to be less bulky than stock trays?
Why are special trays considered to be less bulky than stock trays?
Signup and view all the answers
What is the purpose of using stoppers in a spaced special tray?
What is the purpose of using stoppers in a spaced special tray?
Signup and view all the answers
Which of the following methods is NOT typically used for constructing special trays?
Which of the following methods is NOT typically used for constructing special trays?
Signup and view all the answers
What feature of special trays aids in better retention of dentures?
What feature of special trays aids in better retention of dentures?
Signup and view all the answers
Study Notes
Complete Denture Impression Trays
- Two impressions are required for complete denture prostheses: a primary impression and a final (secondary) impression.
- Impression trays are essential for carrying, confining, and controlling impression material in the patient's mouth.
- Impression trays facilitate the insertion and removal of impression material from the patient's mouth.
Parts of the Impression Tray
- Body: This consists of a floor and flanges.
- Handle: The handle extends from the union of the floor and labial flange in the midline, shaped like an 'L' to avoid interference with the lip during impression taking.
- Upper trays are used for maxillary impressions, while lower trays are used for mandibular impressions. Upper trays have a palatal portion (the vault), while lower trays have lingual flanges.
Types of Trays
-
Stock Trays: Used for primary impressions.
- Can be used for multiple patients.
- Made from various materials like aluminum, stainless steel, tin, brass, or plastic.
- Come in various shapes and sizes to fit different mouths.
- Dentulous stock trays have long flanges, wide and flat floors, while edentulous stock trays have short flanges, oval and narrow floors.
- Combination flat and oval-floored trays can be used for partial denture work.
-
Special Trays (Individual or Custom Trays): Used for final impressions:
- Constructed from primary casts.
- Advantages:
- More economical with impression material.
- Provide a more accurate impression.
- Provide even thickness of impression material, minimizing tissue displacement and dimensional changes.
- Easier and quicker to use than modified stock trays.
- More accurately adapted to the oral vestibules, leading to better denture retention.
- Less bulky than stock trays, providing more patient comfort.
Special Tray Construction Materials
- Cold-cure acrylic resin (self-cure or auto-polymerizing) is most common.
- Visible light-cured acrylic resin (VLC) is also used.
- Shellac base plate and impression compound can be used occasionally.
- Heat-cured acrylic resin is rarely used.
Types of Special Trays
- Spaced special trays: These can be with or without stoppers.
- Closed fitted special trays
Techniques for Special Tray Construction
-
Finger adapted dough method
- With stoppers: Four stoppers are placed — two at the anterior area (canine area) and two at the posterior area (first molar area) on both sides.
- Without stoppers: A baseplate wax sheet is adapted on the cast and a layer of self-cure acrylic resin is applied. The space left after the wax is removed creates an even distance from the cast, similar to the effect of stoppers.
-
Sprinkle-on acrylic method:
- Undercuts on the cast are eliminated with a thin coat of wax.
- The cast is painted with separating medium (cold mold seal).
- Acrylic resin powder (polymer) is sprinkled over the border area, then mixed with a monomer.
Criteria for Special Tray Construction
- The impression tray must not impinge upon movable structures.
- The borders must be under-extended (2 mm).
- The posterior limits of the impression tray should be slightly over-extended to ensure inclusion of the posterior detail for development of the post-dam area (upper tray).
- The tray should be rigid and of sufficient thickness to prevent fracture during use.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz explores the components and types of impression trays used in complete denture prostheses. Understand the significance of primary and final impressions, as well as the anatomy of the tray. Test your knowledge on the different types of trays and their applications in dental practice.
