Laboratory 8 Flashcards
Custom trays are an important part of final impression techniques. Elastomeric impression materials are more accurate in uniform thin layers ____ thick. For this reason, stock trays should not be used because the unevenness of the impression material can lead to ____.8 The ____ the impression material, the more accurate the impression will be, provided that the material is not____ too greatly during removal. Large bulks of impression material are undesirable since they result in increased ____ during the setting reaction. Sufficient ____ is required to allow for elastic deformation, without permanent distortion during impression removal.
2.0-3.0mm distortion thinner strained polymerization shrinkage bulk
The custom impression tray may be made using either ____ or ____ light cured resin known as ____. We will be using a Triad material known as ____.
auto polymerizing methylmethacrylate resin
visible
triad VLC (Dentsply)
trutray
- With a pencil, outline the extensions of the tray by drawing a uniform line ____ mm apical from the gingival margin.
! o Soften and adapt 2 sheets of baseplate pink wax over the teeth and tissue area within the pencil outline. Two thicknesses of baseplate wax are used to achieve ____ mm of relief between the teeth and the tray. The purpose of the custom tray is to provide a uniform minimum thickness of material. Remove the excess wax by trimming. Note: In complete denture tray fabrication, no ____ layer is used and only the undercuts are blocked out.
2.0
2.0-3.0mm
relief
Create occlusal tray stops within the wax by cutting out a square, measuring about ____ mm over each of the second molars. Make a rectangle measuring
____ mm over the incisor area. (Figure 8-1)
- 0 x 2.0
1. 0 x 2.0
The purpose of the tray stops is to form solid ____ of the tray during the impression procedure and also to establish the proper thickness of impression material between the tray and the occlusal surfaces of the teeth. On the side where the prepared teeth are situated, the stop should be distal to the preparation. (DO NOT place your tray stop on the prepared tooth!)
positive seating
Paint a thin coating of Triad Model Releasing Agent (MRA) over the wax and stone cast. Wipe off any excess MRA. A ____ coating of the releasing agent is sufficient. (Figure 8-
! o This is a ____ layer between the wax and the tray material. A waxy layer on the inner surface of the tray will resist ____ by the impression material and can result in ____ of the impression.
thin
protective
adhesion
distortion
The Triad VLC TruTray Custom Tray Material is a pre-mixed sheet material which is highly stable when cured. The sheets should be protected from direct external light sources when not in use. It will be helpful to turn off your bright desk lamp and switch to the ____ light setting to give you more working time. This mode uses a medium intensity light setting and a non-reactive wavelength of light.
cure-life
- The full arch tray should end at the distal surface of the last tooth bilaterally. DO NOT OVERTHIN THE MATERIAL ON THE RIDGE PORTION OF THE CAST. The tray thickness should be sufficient for overall strength and rigidity to maintain the tray’s shape during impression procedures and when pouring the impression. From the remaining material, form a tray handle and attach this to the tray so that the handle is about ____ of an inch wide and ____ of an inch high at an angle of about ____ degrees.
3/4
3/4
70
Once you have completed tray formation, cure for ____ minutes while the tray is on
the cast.
Remove the cast from the turntable and gently separate the tray from the cast. Leaving the wax in the custom tray, place the custom tray back in the TRIAD unit and cure ____ minute with the up to secure tissue stops. It is important that your tissue stops do not come off of the tray!
Paint the entire tray with TRIAD Air Barrier Coating (ABC) (Figure 8-4). (Both inside and outside of tray). Place the tray on the turntable of the TRIAD Curing Unit tissue side up. Cure for a minimum of ____ minutes.
two
one
tissue side
four
Trim the acrylic borders using acrylic burs to eliminate any sharp areas or undesired thickness (Figure 8-5 and 8-6). Only trim the areas ____ as any smooth area adjusted with an acrylic bur will require further smoothing to return it to the proper finish of the material before adjustment.
needing adjustments
