9.record base and wax rim fabrication

9.9.Record Base and Wax Rim FabricationRecord Base and Wax Rim Fabrication Michael Hamada, DDS andMichael Hamada, DDS andJohn Beumer III, DDS, MSJohn Beumer III, DDS, MS

Division 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 This program of instruction is protected by copyright ©. No portion of this program of instruction may be reproduced, recorded or of this program of instruction may be reproduced, recorded or

transferred by any means electronic, digital, photographic, mechanical transferred by any means electronic, digital, photographic, mechanical etc., or by any information storage or retrieval system, without prior etc., or by any information storage or retrieval system, without prior

permission.permission.

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.

Record Base – An interim denture baseRecord Base – An interim denture base

Used to support wax rimsUsed to support wax rims


• Used for making centric relation recordsUsed for making centric relation records


• Used in making trial denturesUsed in making trial dentures

Characteristics of an Ideal Record BaseCharacteristics of an Ideal Record Base

Strength and rigidityStrength and rigidity Accuracy Accuracy

• The record base should not rock on the castThe record base should not rock on the cast

Smooth, rounded well polished bordersSmooth, rounded well polished borders Thickness of borders and palate must resemble Thickness of borders and palate must resemble

those of the finished denturesthose of the finished dentures• Palate must be 1-2 mm thickPalate must be 1-2 mm thick• Thickness and contour of the denture borders are Thickness and contour of the denture borders are

defined by the land of the master cast. The record base defined by the land of the master cast. The record base must not extend onto the land of the castmust not extend onto the land of the cast

Materials Used for Record BasesMaterials Used for Record Bases

Tray resin Tray resin Brittle but very accurateBrittle but very accurate

Autopolymerizing acrylic resin Autopolymerizing acrylic resin Strong but less accurateStrong but less accurate

Light cure resin Light cure resin Accurate but brittle and expensiveAccurate but brittle and expensive

Fabrication of Record Bases and Wax RimsFabrication of Record Bases and Wax Rims

Separating medium Baseplate wax Wax spatula Hanau torch Hot plate Cloth polishing wheel Large camel’s hair brush Red handle knife Celluloid mm rule Bunsen burner Autopolymerizing acrylic resin

Instruments and MaterialsInstruments and Materials

Procedures*Procedures* Blocking out the Master Casts*

– Undercuts– Frenum areas– Rugai– Irregular surfaces– Redundant tissue areas Mark areas of block out Mark areas of block out

withwith a red pencila red pencil

Flow a thin layer of wax over the outlined areas with baseplate wax

ProceduresProcedures

Blocking out the master casts Block out frenum and

other irregularities

Wax should be thin enough to see through

ProceduresProcedures

Blocked out master casts coated with Alcote tin-foil substitute

Maxillary Record Base FabricationMaxillary Record Base Fabrication

Sprinkle-on technique of resin additionSprinkle-on technique of resin addition


Build up labial flange by alternating polymer and monomer addition

Maxillary Record Base FabricationMaxillary Record Base Fabrication Sprinkle on a thin consistent layer

over the palate


Reinforce the ridge crest to prevent slumpingReinforce the ridge crest to prevent slumping

•Keep the surface moist with Keep the surface moist with monomer to prevent porositymonomer to prevent porosity

•Keep ridge lap areas thin to Keep ridge lap areas thin to facilitate tooth placementfacilitate tooth placement

Mandibular Record Base FabricationMandibular Record Base Fabrication

Manipulate the cast to prevent slumping Build up the flanges

Mandibular Record Base FabricationMandibular Record Base Fabrication

Reinforce the lingual portion of the flange and ridge crest

Record Base PolymerizationRecord Base Polymerization Process acrylic resin in Pressure Pot

– 20 psi– 110 degrees water– 10 to 15 minutes

In absence of a pressure pot, place casts under an over-turned rubber mixing bowl

Record Base PreparationRecord Base Preparation

Then, gently pry the record bases from the master cast

Soak the polymerized record base and casts in hot water to soften the block-out wax


Remove wax which may prevent seating of record base from tissue surface

Gently remove all block-out wax from master cast without damaging surface

Record Base Preparation MaxillaRecord Base Preparation Maxilla

Areas requiring modification Areas requiring modification on unfinished record baseson unfinished record bases

Land

FlashFlash

Record Base Preparation - MaxillaRecord Base Preparation - Maxilla

Trim excess flash

Trim the excess acrylic resin Trim the excess acrylic resin that extends onto the land of that extends onto the land of the cast (flash) as shownthe cast (flash) as shown herehere..

Note: The only portion of the record base that is highly polished is the periphery.

Record Base Preparation - MandibleRecord Base Preparation - Mandible


Thin ridge lap portion of denture base Ridge Lap portion Ridge Lap portion

must be thin must be thin enough to enough to accommodate the accommodate the anterior teethanterior teeth

Record Base Contouring/FinishingRecord Base Contouring/Finishing

Palate should be consistent 1-2mm thick to facilitate speech. Thick record bases may also precipitate gagging.

Pumice the oral (tongue) side of the palate and flanges for patient comfort

Thick maxillary record Thick maxillary record bases and convex contours bases and convex contours of mandibular record of mandibular record bases impinge upon the bases impinge upon the tongue space and prevent tongue space and prevent the patient from articulating the patient from articulating speech sounds in a normal speech sounds in a normal fashionfashion. .

ResultResult – vertical dimension of occlusion and centric – vertical dimension of occlusion and centric relation records made from such record bases may be relation records made from such record bases may be inaccurate.inaccurate.

The “s” sound is particularly The “s” sound is particularly useful when determining the useful when determining the vertical dimension of occlusionvertical dimension of occlusion

Patient in the “S” positionPatient in the “S” position

Completed Record Bases ChecklistCompleted Record Bases Checklist

Palate should be consistent 1-2 mm thick and well adapted

Lingual of ridge of mandible reinforced but concave

Retromolar pad area covered

Thin areas labial to ridge

Roughened ridge areas


No porosity or voids on tissue No porosity or voids on tissue surfacesurface

Flanges smooth and roundedFlanges smooth and rounded

Tissue surfaces well adapted


No excess flash on land area of master casts

Record bases do not rock on master casts and are reasonably retentive

Wax Occlusion Rims - PurposeWax Occlusion Rims - Purpose

Serve as a means of transfer of face bow Serve as a means of transfer of face bow transfer recordstransfer recordsAid in orientation of the incisors and the Aid in orientation of the incisors and the occlusal plane when properly contouredocclusal plane when properly contouredAid in developing contours of the lips and Aid in developing contours of the lips and cheek when properly contouredcheek when properly contouredUsed in developing the vertical dimension Used in developing the vertical dimension of occlusionof occlusionUsed in making tentative centric relation Used in making tentative centric relation recordsrecordsServe as a general aid in selection of teethServe as a general aid in selection of teeth

Instruments and MaterialsInstruments and Materials

• Baseplate waxBaseplate wax• Kingsly scraperKingsly scraper• Wax spatulaWax spatula• Occlusal plane former Occlusal plane former

(hot plate(hot plate)

a)a) Place maxillary record base on Place maxillary record base on the cast.the cast.

b)b) Heat a sheet of baseplate wax in Heat a sheet of baseplate wax in the Bunsen burner until the wax the Bunsen burner until the wax is very pliable.is very pliable.

c)c) Roll the wax into long tube.Roll the wax into long tube.d)d) Starting at the tuberosity, press Starting at the tuberosity, press

the roll of wax against the crest the roll of wax against the crest of the ridge.of the ridge.

e)e) Seal the wax to the record base Seal the wax to the record base with a hot wax spatula. If with a hot wax spatula. If necessary,necessary, fill in the voids with fill in the voids with additional wax.additional wax.

Technical ProceduresTechnical Procedures

f) Heat the occlusal plane former in a f) Heat the occlusal plane former in a flame and carefully form the occlusal flame and carefully form the occlusal aspect of the rim. Catch the melted wax in aspect of the rim. Catch the melted wax in a paper towel.a paper towel.g) Form the buccal and labial contours g) Form the buccal and labial contours with the hot plate in a similar manner. If with the hot plate in a similar manner. If there are voids fill them with wax and there are voids fill them with wax and repeat the process.repeat the process.

Technical ProceduresTechnical Procedures

Maxillary Wax Rim Check ListMaxillary Wax Rim Check List

The occlusal portion of the rim should have the following thickness

a) Molar region - 8 mm b) Premolar region - 6 mm c) Anterior region - 3 mm

As viewed from the lateral perspective the rim should project anteriorly to just beyond the outer edge of the land of the cast.

Lingual contours must not impinge on the tongue space.

Anterior region

Posterior region

Maxillary Wax Rim Check ListMaxillary Wax Rim Check List

The labial and lingual surfaces must be smooth and free of voids

The posterior section of the rim should be tapered to avoid the retromolar pad

The curvature of the anterior portion must simulate the curvature of the edentulous arch

The mandibular wax rim is The mandibular wax rim is fabricated in a similar fabricated in a similar manner, however, the rim manner, however, the rim should be centered over the should be centered over the crest of the ridge.crest of the ridge.

Lingual contours must not Lingual contours must not impinge on the tongue space.impinge on the tongue space.

Mandibular Wax RimMandibular Wax Rim

Completed Wax RimsCompleted Wax Rims

a.a. Face Bow Transfer RecordFace Bow Transfer Record

The face bow bite fork is The face bow bite fork is attached to the wax rim attached to the wax rim and this apparatus is and this apparatus is positioned intra-orally. The positioned intra-orally. The face bow apparatus is face bow apparatus is attached and appropriately attached and appropriately adjusted and transferred to adjusted and transferred to the articulator, permittingthe articulator, permittingproper mounting of the proper mounting of the maxillary cast on the upper maxillary cast on the upper

member of the articulatormember of the articulator..

a. Facebow Transfer Recorda. Facebow Transfer Record

The mounting is carefully The mounting is carefully smoothed and sanded. smoothed and sanded. When you are finished When you are finished allall your mountings must look your mountings must look like this one.like this one.

b.b. Determine Incisor Position and Occlusal PlaneDetermine Incisor Position and Occlusal Plane

Record base and wax rim is Record base and wax rim is placed into position and a placed into position and a “Fox”“Fox” occlusal plane can be used to occlusal plane can be used to verify the proper level and verify the proper level and angulation of the occlusal plane.angulation of the occlusal plane.

If the wax rim does not conform If the wax rim does not conform to the landmarks indicating the to the landmarks indicating the proper plane of occlusion proper plane of occlusion (Camper’s plane) the was rim is (Camper’s plane) the was rim is altered until it does conform.altered until it does conform.

When the wax rim is ideally contoured and mounted and the lower cast mounted on the When the wax rim is ideally contoured and mounted and the lower cast mounted on the on the articulator with a centric relation record, the plane of occlusion is readily seen.on the articulator with a centric relation record, the plane of occlusion is readily seen.

The three determinants of the occlusal plane are readily seen:a) The incisal edge of the central incisorb) The middle third of the retromolar pads bilaterally

b. Determine Incisor Position and Occlusal Planeb. Determine Incisor Position and Occlusal Plane

cc.. Aid in developing contour of the lips and cheeksAid in developing contour of the lips and cheeks ..

Wax rim is contoured with the rim former until the desired lip and cheek contours are developed

d. Determine the Proper Vertical Dimension of d. Determine the Proper Vertical Dimension of OcclusionOcclusion

The wax rims aid the clinician in determining the proper vertical dimension of occlusion.

Wax rims are used as an aid to determine Wax rims are used as an aid to determine the proper vertical dimension of occlusion the proper vertical dimension of occlusion and making centric relation records and and making centric relation records and transferring them to the articulator.transferring them to the articulator.

e. Used to Make Centric Relation Recordse. Used to Make Centric Relation Records

ee.. Used to Make Centric Relation RecordsUsed to Make Centric Relation Records

“VDR”“VDO”

VDO = The length of the face when the teeth are in contact and the mandible or the teeth are in centric relation

f.f. Serves as a General Aid in Tooth SelectionServes as a General Aid in Tooth Selection

The position of the corners of the mouth are marked on the wax rims and the distance between these two marks can serve as a guide to tooth selection.

A wax rim properly contoured in the anterior region A wax rim properly contoured in the anterior region (arrows) aids in positioning the anterior teeth.(arrows) aids in positioning the anterior teeth.

Anterior maxillary teeth are arranged according to the Anterior maxillary teeth are arranged according to the labial contours developed in the patient.labial contours developed in the patient.

f. Maxillary Record Base and Wax Rimf. Maxillary Record Base and Wax Rim

Technology

9.record base and wax rim fabrication