A new method for recording and reproducing cast orientation on a surveytable

Herman B. Dumbrigue, DDM,a and Marianne I. Chingbingyong, DDM, MS, DScb

Baylor College of Dentistry, Texas A&M University System Health Science Center, Dallas, Texas

Cast position on a survey table is determined with an inclinometer, allowing tilt to be measured in1-degree increments in the frontal and sagittal planes. With this device, cast reorientation is simplifiedand tilt modifications can be accomplished accurately because of direct visualization of tilt measure-ments in the 2 planes. (J Prosthet Dent 2003;89:76-8.)

Surveying diagnostic casts is an important step in thefabrication of removable partial dentures (RPD). After asuitable path of insertion is determined, the orientationof the cast needs to be recorded to allow repositioning ofthe cast in the same orientation at subsequent times. Theability to accurately record, communicate, and repro-duce cast orientation is critical to the laboratory fabrica-tion of an RPD framework with the same path of inser-tion as that determined by the dentist. Clinicalverification of the laboratory product can be achieved ifthe master cast can be reoriented accurately.

Conventional methods for recording cast position re-quire marking the cast in several areas to establish a planeof orientation. Tripodization is accomplished by placinghorizontal marks on 3 divergent anatomic areas on thecast.1 These marks define a plane of orientation for re-positioning the cast. The scoring method involves mak-ing 3 vertical marks along the base of the cast on theposterior and lateral areas.1,2 The analyzing rod of asurveyor is aligned with all 3 marks to reorient the cast.

The tripodization and scoring methods are simpleand do not require additional instrumentation. How-ever, use of these methods only allows reorientation ofthe cast on which marks have been placed. Duplicatecasts cannot be oriented to the position of the originalcast accurately unless the marks are captured in somemanner during the duplication process.

Several devices have been described to facilitate therecording and reproduction of cast orientation. Kaloy-annides3 developed a geometric technique for recordingcast orientation that involves using a protractormounted on a surveyor. Knapp et al4 and Bezzon et al5described similar methods in which a pin is attachedvertically to the cast as a means of reorienting the cast ona surveyor. Steas6 developed a device consisting of 3adjustable arms attached to a surveyor that contact thecast at 3 divergent points. Ansari7 described the use of aU-shaped plastic impression tray with a vertical stylus

attached to a surveyor. The tray was indexed to theocclusal surface of a cast with silicone putty material.

The pin method4,5 allows quick and accurate reori-entation of a cast on a surveyor.8 However, like con-ventional methods, cast orientation cannot be repro-duced on duplicate casts. Other devices enable theorientation of duplicate casts but require attachmentof the device to a surveyor.3,6,7 This article describes anew device and method for recording and reproduc-ing cast orientation.

TECHNIQUE

The cast angle tool (CAT) (Patent pending, TexasA&M University Technology Licensing Office, CollegeStation, Texas) consists of an inclinometer (Pitch & An-gle Locator; Johnson Level and Tool Mfg Co, Mequon,Wis.) mounted on the center of a 3.5- � 3.5-inch metalplate with a spring-loaded swivel mechanism (Fig. 1).

aAssociate Professor and Assistant Program Director, Advanced Ed-ucation in General Dentistry, Baylor College of Dentistry.

bPrivate Practice, Carrollton, Texas

Fig. 1. CAT consists of inclinometer that swivels aroundmetal plate.

76 THE JOURNAL OF PROSTHETIC DENTISTRY VOLUME 89 NUMBER 1

The inclinometer rotates about the center of the metalplate to 2 terminal positions that are perpendicular toeach other. Metal stops limit the rotation of the incli-nometer to these 2 terminal positions. The inclinometerprovides tilt measurements in 1-degree increments. Themetal plate has elevated index markers on its undersur-face arranged in an arch configuration that allow index-

ing of the device to the occlusal surface of a cast (Fig. 2,A).

Procedure for recording cast orientation1. Index the CAT to the cast by applying vinyl polysi-

loxane (VPS) occlusal registration material (ImprintSBR; 3M Dental Products, St. Paul, Minn.) to its

Fig. 2. A, Indexing markers on undersurface of metal plate. B, VPS occlusion registration material used to index occlusalsurfaces of cast to CAT.

Fig. 3. Measurement of cast orientation. A, Frontal plane. B, Sagittal plane.

DUMBRIGUE AND CHINGBINGYONG THE JOURNAL OF PROSTHETIC DENTISTRY

JANUARY 2003 77

undersurface and seating the occlusal aspect of thecast into the VPS (Fig. 2, B). After the VPS indexhas set, remove the device from the cast.

2. Secure the cast on a survey table, and use a surveyorto adjust the tilt until the desired path of insertion isobtained.

3. Replace the CAT on the cast by use of the VPSindex, and record the angle of the cast in the frontalplane. Designate the measurement as (�) or (�) todescribe the position of the gauge needle relative tozero degrees (Fig. 3, A).

4. Rotate the inclinometer counterclockwise to its ter-minal position, and record the angle of the cast inthe sagittal plane. Designate the measurement as(�) or (�) (Fig. 3, B).

5. Remove the VPS index from the CAT, and store itwith the patient’s casts. The VPS index can be easilyreplaced on the device for subsequent cast reorien-tation. Record the measurements for cast orienta-tion in the frontal and sagittal planes in the patient’schart as a permanent record of the planned path ofinsertion.

Cast reorientation1. To reorient a cast to the planned path of insertion,

secure the cast on the survey table, and loosen thelocking screw that holds the table in position.

2. Attach the VPS index to the undersurface of theCAT, and place it in the appropriate position on thecast.

3. With the inclinometer in the frontal position, tiltthe survey table laterally until the predeterminedfrontal plane orientation is obtained. Lightlytighten the locking screw of the survey table.

4. Rotate the inclinometer counterclockwise to its ter-minal position, loosen the locking screw, and care-fully tilt the survey table anteroposteriorly to thepredetermined sagittal plane position. Lightlytighten the locking screw.

5. Rotate the inclinometer clockwise to its terminalposition, and verify that the frontal plane angulationhas not been altered. Tighten the locking screwafter frontal and sagittal plane orientations havebeen verified.

DISCUSSION

The CAT is a new device that allows measurement ofcast orientation in the frontal and sagittal planes. Castreorientation with the VPS index is simplified since only

2 positions are being aligned, compared to 3 marks withthe conventional methods. The CAT can orient dupli-cate casts with the same VPS index and is used indepen-dent of a surveyor. Modifications to cast angulation inthe frontal or sagittal planes may be made precisely andmeasured in 1-degree increments with this device.

Disadvantages of this method include the additionalcost for the CAT, because both dentist and laboratorywill need to have one. The VPS index, which is transfer-able between CAT devices, also presents an additionalexpense. The recorded measurements are only valid inconjunction with the VPS index used to record castorientation.

Research is currently being conducted to comparethe accuracy of the CAT method of cast reorientationwith the conventional methods of tripodization andscoring. Results from this study will be presented in asubsequent article.

SUMMARY

A new device that is simple to use and that allows castorientation to be recorded and reproduced has beendescribed.

REFERENCES1. McGivney GP, Carr AB. McCracken’s removable partial prosthodontics.

10th ed. St. Louis: Mosby; 1999. p. 212-3.2. Applegate OD. Essentials of removable partial denture prostheses. 3rd ed.

Philadelphia: WB Saunders; 1966. p. 108-10.3. Kaloyannides TM. Reproduction of tilt of a cast on a surveyor. J Prosthet

Dent 1973;30:465-7.4. Knapp JG, Shotwell JL, Kotowicz WE. Technique for recording dental

cast-surveyor relations. J Prosthet Dent 1979;41:352-4.5. Bezzon OL, Ribeiro RF, Pagnano VO. Device for recording the path of

insertion for removable partial dentures. J Prosthet Dent 2000;84:136-8.6. Steas AD. Recording and reproducing the tilt of a cast on a surveyor. J

Prosthet Dent 1987;57:121-5.7. Ansari IH. A procedure for reorienting a cast on a surveyor. J Prosthet Dent

1994;72:104-7.8. Wagner AG, Forgue EG. A study of four methods of recording the path of

insertion of removable partial dentures. J Prosthet Dent 1976;35:267-72.

Reprint requests to:DR HERMAN B DUMBRIGUE

BAYLOR COLLEGE OF DENTISTRY

TEXAS A & M UNIVERSITY SYSTEM HEALTH SCIENCE CENTER

3302 GASTON AVENUE, ROOM 601DALLAS, TX 75246TEL: (214) 828-8347FAX: (214) 828-8952E-MAIL: hdumbrigue@tambcd.edu

Copyright © 2003 by The Editorial Council of The Journal of ProstheticDentistry.

0022-3913/2003/$30.00 � 0

doi:10.1067/mpr.2003.7

THE JOURNAL OF PROSTHETIC DENTISTRY DUMBRIGUE AND CHINGBINGYONG

78 VOLUME 89 NUMBER 1