Why use a custom tray? Better fit than stock trays Less impression material needed More accurate impression because of better fit

Are there any disadvantages to using custom trays? Yes Cost of laboratory processing Staff time Staff training

What types of procedures warrant the use of a custom tray? Final impressions for full dentures Final impressions for partial dentures Final impressions for multiple crowns Final impressions for bridgework Final impressions for multiple implants

What procedures do not require a custom tray? Orthodontic evaluation Bleaching tray construction Sports guard construction Night guard construction Treatment planning Single crown construction (Dr’s option)

Criteria for an acceptable custom tray: Tray must be sufficiently rigid to hold and support materials needed during tray placement and removal Tray must fit and adapt well to the arch and must maintain patient comfort without impinging on surrounding tissues. Tray must provide accurate adaptation to an edentulous or a partially edentulous arch. Tray must maintain an even distribution of 3 to 4 mm of impression material between itself and teeth.

Criteria for an acceptable custom tray: The completed maxillary tray must cover the teeth and hard palate and extend slightly beyond the gingival margin (but not into muccobuccal fold). The primary materials used to construct custom trays are self-curing acrylic resin, light-cured resin, and thermoplastic material. Regarless of the material used in construction of the tray, a diagnostic model must be prepared first, in accordance with specific guidelines.

Common custom tray materials Self cure resin Light cure resin Thermoplastic (Tak balls) Thermoplastic (Easy Tray) Thermoplastic (Vacuum former sheets)

Steps in construction of custom tray? *Some steps will vary depending on material used in construction Outlining – pencil where the margins of the tray will go

Filling up undercuts Undercuts – recessed areas on a model must be filled in prior to making a custom trays or it will be difficult to remove or place impression tray

Spacer/ Wax Relief Spacer/ wax relief – material used to hold space for impression material, baseplate wax or tissue. When using wax, soften wax over flame or in water bath. Then adapt to model, keep within outline, using wax knife trim excess, when happy with wax use a hot instrument to lute wax to model Spacer stops- prevent tray from overseating, cut 3mm ● or ▲ holes out of spacer. For edentulous place one stop on each 1st molar area and cuspid area. For tray on natural teeth, place stop near tooth but not on it

Spacer/ Wax Relief

Steps continued: Separator- placed on spacer and model to allow easy removal of tray. Petroleum jelly, Coe-sep and Al-cote can be used as a separator. All these materials can be placed with a cotton tipped applicator

Self curing resins steps: Prepare resin material – read instructions for each material before using it For self curing resin: measure out full tray amount of liquid and powder, mix in wax cup or glass jar with tongue depressor Lubricate hands with petroleum jelly When mix has reached doughy stage, remove from cup

Self curing steps continued: For upper tray form the resin into a patty shape (approx. size of spacer) adapt to cast, extend slightly posterior from spacer, trim excess with lab knife For lower model form material in a hot dog shape and proceed as above Use excess material to form handle, place a drop of monomer on handle and on tray, attach handle so it extends out of mouth in center of tray and is parallel to occlusal surfaces, hold handle until material becomes firm.

Finishing custom trays: Some materials require extended curing time for final cure to take place Rough areas can be adjusted using sandpaper rolls on the lathe or acrylic burs on the lab handpiece All areas should be checked for sharpness; and eliminated to prevent tissue injury Final smoothing is done with rag wheel, pumice and water on the lathe