03 02 lower special tray construction

Week 3 Session 2Anatomy Quiz & Lower Special Tray

Construction

Unit 6ADT4305

Part 1

A short quiz of upper oral anatomy and terminology

PLEASE PUT ALL NOTES AWAY

C

D

B

A

E

Identify the zones lettered A-ENOT THE STRUCTURES

FGHI

Identify the CUSPS lettered F > I

MESIAL

DISTAL

PALATAL

JKLMN

Identify the oral structures lettered J > N

Answers

What did you remember?

Answers A to G

A. LabialB. BuccalC. PalatalD. LingualE. BuccalF. Mesiobuccal cuspG. Mesiopalatal cusp

Answers H to N

H. Distobuccal cuspI. Distopalatal cuspJ. Upper labial frenumK. RougaeL. Upper right buccal frenum (Just ‘buccal

frenum’ does not count)M. Hard palateN. Tuberosity

Part 2

Making an edentulous lower special tray for ZOE (Zinc Oxide Eugenol)

Mark line of the ridges and outline of the sulcus

Identify location for rests, in the second premolar/first molar region

Posterior margin to be

just above the retromolar pad

Identify areas of undercut e.g. below retromolar pad and block

out with wax

Carefully adapt a sheet of light cure polymer

Do not over thinIf the cast shows through add

more material

Initial adaptation

Initial trimming

Push the material into the sulcus ensuring the material fully

extends into it

Using a sharp tool carefully trim the material to the marked

extension.

Trim all around the sulcus to the extension identified

Make a handle approximately 20mm long, 15mm wide and 5mm thick taper towards the tip.

Flare the base of the handle to ease adaption to the base material.

Side view

Position the handle in the midline of the anterior ridge.

The handle should be between 22mm and 25 mm from the depth of the

sulcus.It should be vertical but a slight anterior

tilt may be acceptable.When correctly positioned the flared

edges are blended into the base material.

Rests

• The rest is made in the same way as the handle although slightly shorter.

• The base is flared and the rest positioned centrally on the ridge approximately in the position of the second premolar/first molar.

• The rest should be a maximum of 15 mm from the depth of the sulcus.

• If the rest is placed too far lingually it will restrict the tongue, too far buccally will distort the cheeks.

Rests

• When both rests are completed the tray is checked and then smoothed with petroleum jelly. This smoothes the material and acts to seal the material to reduce surface inhibition of the set by oxygen in the atmosphere.

• The tray is placed in a light curing box and cured for 3 minutes. When cured the tray is removed from the cast, the tray is turned over and the fitting surface cured