8. Boxing Impressions and Making Casts8. Boxing Impressions and Making Casts

John Beumer III, DDS, MSJohn Beumer III, DDS, MSandand

Robert Duell, DDSRobert Duell, DDSDivision of Advanced Prosthodontics, Division of Advanced Prosthodontics, Biomaterials and Hospital DentistryBiomaterials and Hospital Dentistry

UCLA School of DentistryUCLA School of Dentistry

This program of instruction is protected by copyright ©. No portion of This program of instruction is protected by copyright ©. No portion of this program of instruction may be reproduced, recorded or transferred this program of instruction may be reproduced, recorded or transferred by any means electronic, digital, photographic, mechanical etc., or by by any means electronic, digital, photographic, mechanical etc., or by any information storage or retrieval system, without prior permission.any information storage or retrieval system, without prior permission.

ProceduresProcedures

Box impressions Pour master casts in stone Trim and index cast

Boxing Master Impressions and Boxing Master Impressions and Making Master CastsMaking Master Casts

• Purpose - Fabricate a cast thatPurpose - Fabricate a cast that• Preserves the peripheral rolePreserves the peripheral role• Provides a protective rim around the cast Provides a protective rim around the cast

(land). This rim (land) must be 4-6 mm (land). This rim (land) must be 4-6 mm wide.wide.

• Produce a dense cast of vacuum mixed Produce a dense cast of vacuum mixed stone of the proper dimension (10- 15 mm stone of the proper dimension (10- 15 mm thick) to permit flasking.thick) to permit flasking.

Boxing the Maxillary Master ImpressionBoxing the Maxillary Master Impression

Two methodsTwo methods• Pumice and plaster methodPumice and plaster method• Bead and box with wax rods and Bead and box with wax rods and

sheet stripssheet strips

Boxing - Beading and Boxing with WaxBoxing - Beading and Boxing with Wax

1) Apply a layer of sticky wax around the the 1) Apply a layer of sticky wax around the the impression 3 mm below the periphery as impression 3 mm below the periphery as shown.shown.

Maxillary impression

Boxing – Beading and Boxing with WaxBoxing – Beading and Boxing with Wax

2) Apply and seal Apply and seal rods of beading wax rods of beading wax to the sticky wax on to the sticky wax on the impression to form the impression to form the land. the land.

Boxing – Beading and Boxing with WaxBoxing – Beading and Boxing with Wax

3) Wrap a sheet of red boxing wax around the beading wax to form a container. All joints must be sealed with hot wax to prevent stone from leaking through.

Boxing -Plaster and Pumice MethodBoxing -Plaster and Pumice Method

1)1) Draw a line around the impression 3 Draw a line around the impression 3 mm up from the periphery. mm up from the periphery.

2)2) Set impression in a 1:1 mixture of Set impression in a 1:1 mixture of plaster and pumice.plaster and pumice.

3)3) Push impression halfway into the Push impression halfway into the mix.mix.

4)4) Push the mix up around the Push the mix up around the impression with a spatula to create impression with a spatula to create a land at the level of the line drawn a land at the level of the line drawn on the impression.on the impression.

5)5) When the mix is set, trim on the When the mix is set, trim on the model trimmer to create a 4-6 mm model trimmer to create a 4-6 mm land.land.

Boxing – Plaster Pumice MethodBoxing – Plaster Pumice Method

6) Wrap the impression in sheet wax and seal it to the plaster pumice boxing with hot wax

7) Brush a light layer of vaseline onto the plaster land area so that the stone of the cast does not stick to the land

8) The container made from the wax sheet must be at least one half inch above the highest point of the impression to create an adequate base to the cast.

Prepare a dense mix of yellow stone using your vacuum Prepare a dense mix of yellow stone using your vacuum mixer and vibrate the stone into the boxed impression. Be mixer and vibrate the stone into the boxed impression. Be careful to avoid entrapment of air bubbles. careful to avoid entrapment of air bubbles.

Pouring the CastPouring the Cast

Boxing the Mandibular ImpressionBoxing the Mandibular Impression

Apply a layer of rubber base adhesive or hot sticky wax to the impression as shown.

This layer should about 3 mm above the height of the border of the impression.

Boxing the ImpressionBoxing the Impression

•Apply a strip of red beading wax to the sticky wax layer to Apply a strip of red beading wax to the sticky wax layer to form the land of the cast.form the land of the cast.•Close the lingual tongue area of the impression with a Close the lingual tongue area of the impression with a sheet of wax or with pumice and plaster.sheet of wax or with pumice and plaster.

Boxing the ImpressionBoxing the Impression

•Wrap a layer of boxing wax around the impression to Wrap a layer of boxing wax around the impression to form a wax container.form a wax container.•All joints must be sealed to prevent seepage of stone All joints must be sealed to prevent seepage of stone into undesirable areasinto undesirable areas

The same result can be The same result can be achieved by boxing the achieved by boxing the entire impression with a entire impression with a mixture of plaster and mixture of plaster and pumice (to form the land pumice (to form the land area) and boxing wax to area) and boxing wax to create the enclosure.create the enclosure.

If you use this method be sure to coat the plaster pumice If you use this method be sure to coat the plaster pumice mixture with vaseline before you pour stone into mixture with vaseline before you pour stone into impression so that cast will separate from this mixture.impression so that cast will separate from this mixture.

Boxing the ImpressionBoxing the Impression

Pouring the CastPouring the Cast

•Vacuum mix the yellow stoneVacuum mix the yellow stone

•Carefully vibrate the stone into the impression. Carefully vibrate the stone into the impression. Start on the buccal of one side and progress to Start on the buccal of one side and progress to other side.other side.

Before you pour the cast Before you pour the cast make sure the boxing is make sure the boxing is sufficient to permit the sufficient to permit the fabrication of a cast at fabrication of a cast at least 10 mm thickleast 10 mm thick.

Remove the Cast from the ImpressionRemove the Cast from the Impression::

• Wait 1 hour for the stone to setWait 1 hour for the stone to set

• Immerse the cast-impression into hot water for 5 minutes Immerse the cast-impression into hot water for 5 minutes to soften the compound border molding before separating to soften the compound border molding before separating the cast from the impression.the cast from the impression.

After heating the compound in a water bath, carefully separate the cast from the impression

Retrieving the CastRetrieving the Cast

• With a model trimmer flatten the base so that the base is parallel to the ridge. The cast should be ½ inch thick.

• Trim the sides of the cast so that there is an even 4-6 mm of land around the cast.

• Trim the land with a burr or sharp knife and reduce so that the depth of the peripheral roll is 2-3 mm throughout.

Trimming the CastTrimming the Cast

Trim master casts. Trim master casts. The base should be no The base should be no thicker than 15-20 mm.thicker than 15-20 mm.

If the base is too thick the If the base is too thick the cast will not fit within the cast will not fit within the confines of the denture flask. confines of the denture flask. The land of the cast must The land of the cast must be at the same level as the be at the same level as the edge of the lower member of edge of the lower member of the flask.the flask.

Trimming the Master CastTrimming the Master Cast

Completed Master CastCompleted Master Cast

Land Land (4-6mm (4-6mm thick)thick)

Base (15-20 mm thick)Base (15-20 mm thick)

Depth of peripheral Depth of peripheral roll (2-3 mm)roll (2-3 mm)

The base for this cast was insufficient and eventually it The base for this cast was insufficient and eventually it fractured necessitating remaking of the impressionfractured necessitating remaking of the impression

Trimming the Master CastTrimming the Master Cast

Master CastsMaster Casts

These casts have These casts have been properly been properly trimmed and marked. trimmed and marked.

Place rounded notches (arrows) Place rounded notches (arrows) on the bottom of the master cast. on the bottom of the master cast. These notches will later be used to These notches will later be used to remount the processed denture remount the processed denture back onto the articulator.back onto the articulator.

The notches should be placed on the back and on the sides of the casts.The notches should be placed on the back and on the sides of the casts.

Anterior land

Cast Landmarks - MaxillaCast Landmarks - Maxilla

Midline

Incisive papilla

Lines indicating the crest of the ridge

Cast Landmarks -MandibleCast Landmarks -MandibleMidpoint of

retromolar pad

Land Mark on land indicating the midpoint of the retromolar pad