Edentulous gnathologic recordings utilizing “vacustatics”

Edentulous

gnathologic

recordings

utilizing

“vacustatics” Gary C. Hunt, D.M.D., San Mateo, Cdif.

and James N. Yoxsimer,

D.D.S.

U

tilization of a pantograph for accurate recordings requires rigid fixation of the clutches to the upper and lower jaws. In complete dentures, where dentists are concerned with movable, unstable edentulous ridges, difficulty in stabilizing the pantograph has always been a potential source of error. Various methods have been suggested to stabilize recording clutches while developing jaw relation records and to facilitate the location of the hinge axis. The Almore clamp’ in combination with zinc oxide/eugenol paste as a cementing medium has been relatively successful with the Almore hinge-axis locator, but the Almore clamp, used in extraoral pantography to record mandibular movement, was found to be entirely inadequate to stabilize the recorder. BuffingtorP* suggested that the “vacustatic” technique could be utilized for the stabilization of recorders such as the Stuart and Denar pantographs,t but he gave no technique for the dentist to follow. The pantograph serves the dentist best when it can be used to diagnose the essential character of lateral and protrusive mandibular movements-their paths and sometimes unique curvatures. If the edentulous patient has an immediate sideshift of the mandible at the beginning of the lateral excursive movement, it is essential that the cusps which form the occlusal contacting surfaces of the dentures have a small surface in which they can move without contacting one another. If provision is not made for this movement in the restored occlusion, there will be constant interference on the working and balancing sides. Destructive occlusal forces are expressed biologically in the rapid breakdown of the residual alveolar crest, temporomandibular joint symptoms, and soft-tissue ulcerations. The mechanical display of this overloading is observed in rapid wear of acrylic resin teeth or frequent breaking or chipping of porcelain teeth. The purpose of this article is to explain a simplified vascustatic technique for Read before the California table clinic at the International *Procedure

manual, APM-Sterngold,

tPersona1 communication:

588

Dental Association, San Francisco, Calif., and presented Academy of Gnathology, Mexico City, Mexico. B. Buffington,

San Mateo, April,

Calif.

1974.

as a

Volume Number

Edentulous

35 5

Fig. 1. Clutches are attached vertical relation of occlusion.

gnathologic

to recording

recordings

bases with

using vacustatics

autopolymerizing

589

resin at the correct

Fig. 2. Polyurethane tubes are attached to the recording bases in the second premolar Opposite ends of the tubes are attached to a saliva ejector-adaptor.

region.

clutches to edentulous ridges and obtaining accurate pantographic recordings. The stability of vacustatic clutches is evidenced by the ability to repeat the pantographic border movements an indefinite number of times. This technique can be used as an adjunct for the patient who has had a history of unsuccessful dentures. Most dentists agree that occlusion is one of the factors, if not the most important for successful restorative procedures.

securing

VACUSTATIC Impressions

RECORDING

( 1) Use the technique Mounting

on

Whip-Mix*

TECHNIQUE of choice to develop the master casts. or suitable

type

of articulator

(1) Make a face-bow transfer using the Whip-Mix Quick-Mount face-bow. (2) Mount the maxillary cast on the articulator. (3) Establish and transfer centric and vertical relationships to the instrument with maxillary and mandibular occlusion rims. (4) Mount the mandibular cast on the articulator. Clutch

fabrication

( 1) Remove the occlusion rims from the mounted casts. (2) Draw an outline with an indelible pencil on the border of the maxillary master cast 2 mm. short of the mucobuccal fold and from hamular notch to hamular notch. The distal extension of the posterior region should be drawn from notch to notch about 2 to 3 mm. posterior to the fovea palatini. (3) Draw an outline on the border of the mandibular master cast 2 mm. short *Whip-Mix

Corporation,

Louisville,

Ky.

590

Hunt

J. Prosthet. Dent. May, 1976

and Yoxsimer

Fig. 3. Interconnecting channels are cut across the tissue surface of the maxillary recording base with a large, round carbide bur. The channels are cut from the connector intake along both sides of the ridges and across the palate to create equal distribution of vacuum forces. Fig. 4. A channel is cut in the tubing base with a No. 558 carbide bur.

embedded

on the tissue surface of the lower

recording

of the mucobuccal fold from the buccal side of the retromolar pad on one side to the same point on the other side and similarly on the lingual side from the mucolingual fold to mucolingual fold. (4) Block out undercuts on the casts with wax or wet asbestos strips. (5) Make the upper and lower bases on the casts with any tray acrylic resin. Bend a Coralite plastic saliva ejector, + heated in hot water, and adapt it to the ridge of the lower cast. The saliva ejector is adapted and fused to the base material with autopolymerizing acrylic resin. (6) Trim the recording bases to the outline drawn on the casts. (7) Using the previously established vertical relation from the articulator, attach plastic Denar clutches? for edentulous mouths to the bases with autopolymerizing acrylic resin (Fig. 1). The upper recording clutch has a flat plane. The lower recording clutch provides a central bearing pin at the established vertical relation of OCL elusion. (8) On the maxillary base, make a hole in the buccal flange in the region of the second premolar to accept a clear piece of polyurethane tubing,$ 3/{s inch in diameter and about 6 inches long. The urethane tubing acts as a connector and joins the resin base to the rubber tubing of the vacustatic controls. Complete a similar procedure for the lower arch. Both connectors should exit from the second premolar region, otherwise they will interfere with the recording clutches and recorder *Harry

J. Bosworth

Company,

tDenar

Corporation,

Anaheim,

Chicago,

Ill.

Calif.

$This tubing was that used for aquariums.

Volume 35 Number 5

Edentulous gnathologic

recordings using vacustatics

Fig. 5. Border molding material is added to the border and posterior maxillary

recording

palatal

591

seal area of the

base with a plastic syringe.

Fig. 6. The vacustatic

machine

is set at 10 inches of mercury

pressure

(5 p.s.i.).

crossarms during recording movements. Bend the connectors to join a Y-shaped saliva ejector-adaptor. * Bending the connectors to correct angulation can be expedited by using hot water (Fig. 2). (9) Open the central bearing screw about 2 to 3 mm. to allow for tissue resiliency. (10) With a No. 10 round carbide bur, cut channels on the tissue surface of the upper base from the connector intake along both sides of the ridges and interconnecting channels across the palate to give better distribution of vacuum forces (Fig. 3). Cut a channel in the tubing embedded in the inner side of the lower base from the first molar to first molar with a No. 558 carbide bur (Fig. 4) . Border

molding

with

vacustaticG-

3

(1) Add border material+ or sapphire powder and liquidx to the border of the maxillary resin base and the posterior palatal seal area with a plastic syringe (Fig. 5). Insert the base in the mouth, and attach the tray to the vacustatic machine.t Set the vacuum level at 10 inches of mercury pressure (5 p.s.i.) (Fig. 6). (2) Instruct the patient to go through border-molding exercises of sucking, grinning, kissing, moving the jaw from side to side, and the like while the vacuum is at 10 inches of mercury. Have the patient say “ah” and attempt to blow through the nose with fingers compressing the nostrils to flex and perfect the posterior palatal seal. (3) After 3 minutes, remove the tray and examine the borders for overextension. *Johnson & Johnson, East Windsor, N. J. tAPM--Sterngold, San Mateo, Calif. $Harry J. Bosworth Company, Chicago, Ill.

592

.I. Prosthet. Dent. May, 1976

Hunt and Yoxsimer

Fig. 7. Border seal.

molding

material

is added to the maxillary

Fig. 8. Border molding with a plastic syringe.

material

is added to the border

Fig. 9. Border seal.

molding

material

is added to the mandibular

Fig. 10. Both clutches are placed in the mouth cury pressure (5 p.s.i.) .

base until of lower

there is an atmospheric

mandibular

base until

recording

base

there is an atmospheric

and secured by a vacuum

at 10 inches of mer-

(4) Add border writing material until an adequate seal is developed (Fig. 7). (5) Add border writing material or sapphire powder and liquid to the border of the lower base with a plastic syringe, and insert the base m the mouth (Fig. 8). Attach the tray to the vacustatic machine, and set the vacuum at 10 inches of mercury pressure (5 p.s.i.) (Fig. 6). (6) Instruct the patient to go through border-molding exercises, such as sucking, grinning, moving the jaw from side to side, touching the sides of the cheeks, and wetting the borders of the lips with the tongue, to help create an atmospheric seal and stabilize the lower base.

Volume 35 Number 5

Edentulous

Fig. 11. Hinge-axis

Fig. 12. Left anterior

recording

gnathologic

flags and locators

recordings

using vacustatics

593

are assembled and attached.

plate,

Fig. 13. Left posterior vertical and horizontal traced three times to verify the record.

recording

plates. The recordings

have been re-

(7) After 3 minutes, remove the tray and examine the borders for overextension. (8) Add border writing material until an adequate seal is developed with no evidence of overextension (Fig. 9) . Making

the pantographic

recording

( 1) Place both clutches in the mouth, and secure them with the vacuum at 10 inches of mercury pressure (5 p.s.i.) (Fig. 10). (2) Test for noninterference in centric and eccentric positions by having the patient move the mandible forward, backward, and laterally while maintaining the

594

Hunt

and Yoxsimer

J. Prosthet. Dent. May, 1976

central bearing pin on the central bearing plate. This procedure also helps to rid the patient of proprioceptive memory. (3) Attach and assemble the Denar hinge-axis locators and flags (Fig. 11) . (4) Locate the right and left hinge-axis points. Tattoo both locations on the skin for future reference. (5) Attach and assemble the pantograph to the clutches in the mouth using the hinge-axis locations. Proceed with pantographic recordings using established methods. Recording plates should be retraced three times to insure stability of the clutches (Figs. 12 and 13).

ADVANTAGES AND DISADVANTAGES OF VACUSTATIC TECHNIQUE Advantages. (1) Clutches have better stability during all border movements of the mandible. (2) There is greater accuracy of hinge-axis location as evidenced by split-cast checks using two to four thicknesses of wax when making centric registrations. (3) Clutches can be resecured easily if they become loose. When a cemented clutch comes loose, old cement must be removed and recementing done which is time-consuming. (4) There is better retention with poor mandibular ridges. (5) Clamps which can be cumbersome and uncomfortable in securing lower clutches are not necessary. Disadvantages. ( 1) There am additional expenses for vacustatic equipment. (2) Additional time is spent in border molding and fabricating special clutches for pantographic recording. (3) There is an additional financial commitment for the patient.

CONCLUSION AND SUMMARY Securing clutches to edentulous ridges by vacustatics for a pantographic recording is useful for effecting a desirable result. This technique is a possible answer for those edentulous patients with occlusal problems who have never known comfort while wearing dentures. A procedure has been described utilizing a modification of the vacustatic technique to obtain accurate pantographic recordings on edentulous patients. These recordings enable the dentist to develop a gnathologic-oriented occlusion for the problem denture patient in an attempt to eliminate destructive loading forces on the residual ridges.

References 1. Lauritzen, A. G.: Atlas of Occusal Analysis, Boulder, Colo., 1974, Johnson Publishing Company, pp. 170-176. 2. Buffington, B. C.: Stabilizing Record Bases With Controlled Subatmospheric Pressure, J. PROSTHET. DENT. 21: 14-18, 1969. Pres3. Kubalek, M. V., and Buffington, B. C.: Impressions by the Use of Subatmospheric sure, J. PROSTHET. DENT. 16: 213-223, 1966. 351 N. SAN MATEO DR. SAN MATEO, CALIF. 94401