individual tray
DESCRIPTION
individual tray fabrication of FPD,RPD,CDTRANSCRIPT
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