individual tray

Individual Tray

國泰汐止分院牙科第一年住院醫師

楊舒涵

Object

Improves the accuracy of an elastometric impression by limiting the volume of the material

Opposite is true for reversible hydrocolloid

Tray material

1.Autopolymerizing acrylic resin

2.Thermoplastic resin

3.Photopolymerized resin

Autopolymerizing materials

Ostron Tray resin

Thermoplastic resin

Easy Tray:soften in water bath and adapted manually to the spaced cast

Vacuum formed tray:much more thicker and more rigid than those used for make provisional restorations

Light-polymerized materials

Triad VLC resin custom tray material:adapted to the spaced cast

Evaluation

Tray rigidity is important Resin thickness of 2~3mm are needed for adequate

rigidity Clearance of tray and the teeth should also be

2~3mm Greater clearance is necessary for the more rigid

polyether

Custom tray for FPD

Tray border

On diagnostic cast, using a pencil: approximately 5mm apically to the crest of the free gingiva

Maxilla:covering the entire palate is not necessary (but necessary if removable appliance is planned)

Posterior border should not extend farther than the junction of hard and soft palate

Space for impression material

Baseplate wax 2.5mm thick, trim wax margin back to pencil line just visible

Or dripping cast in molten wax 3~4 times

Stopper placement

Three stops maintain even space for the impression material

On non-centric cusp of teeth that will not be prepared

If all teeth are involved, use larger soft tissue stop: Crest of alveolar ridge; Center of the hard palate

Made by removing wax at an angle of 45 degrees to the occlusal surface

Tray fabrication

Tinfoil on wax prevent melt Gently adapt resin with

consistent thickness to the cast Handle made; buccal ridges

can also be added After polymerizing, trim with

bur

Evaluation Rigid; thickness 2~3mm 3~5mm cervical to gingival margin Shaped to allow frenum, muscle attachments Stable on cast; stoppers maintain impression

thickness 2~3 mm Handle fit between pt's lip Pressure to prevent lifting while setting Made 9 hours before using; or 5minutes in boiling

water then cool to room temperature

Custom tray for CD

Tray border

Preliminary impressionoutlined with marker on the preliminary impression or poured cast

impression material and tray

ZOE:close fitting tray

elastomer, alginate:Spaced custom tray

maxillary provide space :

(not used if ZOE as impression material)baseplate wax; 1 mm thick; within outlined border ;posterior seal should not covered by wax spacer

tray: 2-3 mm thick; a stepped handle at anterior region

Premise:all denture-bearing area reflected in the tray's extension

border molding – tray preparation

Wax left when border molding

Space for border moldingcustom tray reduced to 2mm shorter of the reflections

Tray contains hamular notch and extend 2mm posterior to the vibrating line

Border molding

Record all simultaneously - polyetherreduced insertion numberavoid errors

Record in sections – stick impression compound

Section:labial =>buccal vestibule=>posterior palatal area

Border molding with polyether

Adhesive留下 wax spacer, 但把靠近 border 的修掉混 polyether但 catalyst 少一點用 syringe 加在 border和 palatal seal( 用沾水的手塑型 ) lip 拉高 ,tray 放入檢查 border 如果材料不夠就用手沾口水把旁邊的材料移過來

Border molding with polyether(maxillary) 

@lip 上外下內拉@frenum 外下內前後拉@buccal flange 外下內拉@ 張大嘴 下頷左右動Setting後 tray 拿出檢查 border: 應為 rounded, 小缺陷以 polyether補 ,tray 的過度延伸會透出 polyether. 應調整

preparing tray for final impression

remove wax , excess material

Buccal frenum 間 , flange 厚不要超過2,5~3mm 進入 undercut 的也拿掉

最後除了 posterior area , 再均勻拿掉 0.5mm

Holes :palate of tray ( if soft tissue mobile, relief residual ridge)

Mandibular wax spacer:1 mm

below the mylohyoid ridge; on crest and slopes of the residual ridge

buccal shelf uncovered

Handles:

20 mm height

anterior teeth

1st molar region

border modeling

wax left

tray trim to 2 mm Shorter than limiting Structure

Movements,

lip: 外上內 buccal frenum : 外上內前後 Cheek 頰上內 閉口 舌 : 伸、頂 palate

開口

Evaluation

必須能舌舔 vermilion border 時 , tray 無明顯移位。

移除 wax 和修掉 0.5mm molding material

alveolar groove 和 retromolar pad 上每 10mm打洞

Custom tray for RPD

Diagnostic cast A new impressionA new impression in a rigid stock tray must be

made if extensive surgery and extractions were performed after making the diagnostic cast

A duplicate of the diagnostic castduplicate of the diagnostic cast should be made, on which the individual tray can be fabricated

maxillary Outline tray border

Wax spacer 2~3 m shorter than outlineno wax over posterior palatal sealexpose incisal edges of central incisorbevel wax

block undercut

If use alginate=>additional wax on teethIf rubber base or silicone=>省略

Release agent

maxillary Tray fabrication with handle

Peel wax out

rounding border of the tray

Holes:alginate:alginate:at 5 mm interval ; throughout tray except alveolar groove area (for lock material)mercaptan rubbers (polysulfide)mercaptan rubbers (polysulfide):only median raphe and incisive papilla (for relief)

mandibular

Wax spacer does not cover the buccal shelf region(these areas provide the primary support for the mandibular RPD)

Holes:alginatealginate=>throughout traymercaptan rubber(polysulfide)mercaptan rubber(polysulfide) =>only alveolar groove (for relief)

如果不使用 secondary impression technique,則使用 individual tray印模可視為做活動假牙的必要步驟

Tray design

British Dental Journal 187, 423 - 426 (1999);The design and use of special trays in prosthodontics: guidelines to improve clinical effectiveness