03. Custom Trays

Custom Trays • Individualized trays for making final impressions • Made on a diagnostic cast

Purpose of a Custom Tray • Improve retention (border molded) • Minimize: – Impression material distortion • Uniform thickness • Rigid tray

Purpose of a Custom Tray • Minimize: – Tissue distortion • Less viscous material • Accurately adapted tray

– Costs • less impression material used

Custom Material • Light-cure resins (Triad) • Auto polymerizing acrylic resin (e.g. SR-Ivolin) – Fume hood

• Vacuum-form poly vinyl • Thermoplastic materials

Monomer Hygiene • Autopolymerizing resins have a liquid monomer that should be used in a fume hood • Light cure materials for students

Extension • 3-4 mm short of the peripheral role • Diagnostic casts usually overextended (irreversible hydrocolloid)

Extension • Outline the depth of vestibule – vertical portion turns toward horizontal – Through hamular notches across vibrating line

• Provide room for frenal attachments

Block-Out Undercuts • Baseplate wax • Prevent tray from locking onto cast • Lubricate cast (Petroleum jelly or Alcote)

Wax Spacer • One thickness of base plate wax over the cast • Trim line in vestibule • Trim to“butterfly” configuration glandular tissue

Wax Spacer • Minimizes hydraulic pressures – Do not place relief over blockout – Already space from tissue

• Provides room for impression material

Triad Resin • Light-cure – Heat will melt wax spacer – Cure under water – Cures on exposure to ambient light

Triad Resin • Exposed surface has air inhibited layer – Air Barrier Coating • Cytotoxic • Must be thoroughly removed

– Cure under water

Triad Resin • Wear gloves to minimize exposure to material – Hypersensitivity potential minimal

Tru-Tray Material • Remove from wrapper • Adapt the resin over the spacer • Palatal area adapted first

Large Casts • Use portion of another sheet • Adapt well until seam is gone • Reclose material in wrapper, tape shut • Infection control

Tru-Tray Material • Trim excess with a scalpel, then readapt • Cut down through resin • Pulling blade will tear resin

Trimming the Tray Anterior , Maxillary Tray view Base of Cast

Lateral , Mandibular view Tray Auxillary handle

Land areaoftoo high makes Narrow notch Land area of to trimming acrylic and removal frenum for labial frenum fromficult cast difBroad buccal trimming removal ficult from

Handle Addition • Small vertical handle – Does not pull vestibule

• Add before curing

Auxiliary Handles Mandible • For stabilization • Orientation the tongue • Area of 2nd premolars / 1st molars

Curing in Water • Prevents wax meltdown • Water hazard • Ensure: – Top of container well sealed – Outer container surface dry

Cure Time • 4 minutes • Cooling effect of water may extend cure time

Finish • Arbor-bands and acrylic burs • Round and smooth edges • Mask and eye protection

Finish • Do not polish - adhesion • No holes until border molded

Tray for Border Molding with Partner • More difficult than edentulous border molding – Removal from teeth & undercuts – Easier to lock in place – Hybrid design

Tray Design ftoirsatlsopw aceerassh o u l d t a p e r a b i t t o w a r d th e o c c l u s a l yrem ovalfromthesecondspacer. N o t e l e n g t h o f p e r i p h e r y i s d i f f e r e n t . O eostihdeeriisslsohnogrtfoto rbaolrodw erem o ledring, trhen em a s i oval Acrylicresin 1stwaxspaceronlyoverteeth 2ndspacertovestibuleononeside