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New device for accurately recording centric relation
CRANIOMANDIBULAR
FUNCTION
AND DYSFUNCTION
SECTION EDITOR
GEORGE A. ZARB
New device for accurately
recording
centric relation
J. B. Woelfel, D.D.S.* Ohio State University, College of Dentistry, Columbus, Ohio
D
entists have used many methods and devices in an attempt to precisely locate and record the centric relation position of the mandible.lTz2 No single method has become universally accepted23-26although several techniques have achieved varying degrees of popularity. These include needlepoint tracing devices*; holding the tip of the tongue back in the soft palate; telling the patient to swallow while closing; having the patient pull the lower jaw back24or “stick the upper jaw out;” having the patient relax the mandible and let the dentist manipulate it upward and posteriorly’s “a 12,21,27,28; and telling the patient to relax and close naturally.24 More precise but less popular methods use clutches and a pantographic recording of mandibular border movements 3-5*“2 ‘6,29-33 an acrylic resin jig (Lucia jig)‘, ‘I, ‘8,2’ (Fig. ;), cotton ro11,12tongue blade,‘O popsickle stick,2’,24 narrow strip of soft metal,9*1’*24firtn wax,2’ or a leaf gauge anteriorly (Fig. 2) to exert an upward and posterior guidance during closure.1° The least accurate and most unreliable methods are the functional chewin,2p34the use of electromyographic recording, the MyoMonitor (Myo-tronics Research, Seattle, Wash.),24 Boos power points (Boos Dental Laboratory, Minneapolis, Minn.), True-Centric device (Ticonium Co., Albany, N.Y.), and others. Neuromuscular relaxation is an integral part of a physiologically sound and scientific recording method. Patients can be conditioned by wearing an acrylic resin maxillary occlusal splint (bite plane) for a short time, or until the mandible has assumed a stable comfortable position before making a centric relation jaw registration.6s“9 I932’,33,35-39This applies to different types of prosthodontic treatment. 19,2’,28,39*4o Otherwise, the dentist should at least determine the extent of occlusal discrepancies in mandibular dysfunction patients by testing the existent occlusal error by means of a leaf gauge. ‘“,22,26*4’-44 Research has shown that when a patient bites firmly on a leaf gauge between the incisors, the condyles appear to seat in the most superior and comfortable posterior position.20 This narrow anterior vertical stop forms a tripod effect between the anterior teeth and the condyles9F”,24 as the patient’s closing musculature functions freely without conflicting proprioceptive guidance caused by deflective tooth contacts.“, I2915,2’, 34,45Observing, recording, and eliminating undesirable tooth interferences is dependent on precise *Professor, Division of Prosthodontics.
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Fig. 1. Front and side views of Lucia jig, which increases vertical dimension minimally. It provides a narrow ramp inclined toward palate. Mandible is guided posteriorly as lower incisors slide easily on ramp.
and repeatable neuromuscularly relaxed closures of the mandible in the centric relation arc. It is of paramount importance that existing occlusal discrepancies be eliminated before, or in conjunction with, any relatively extensive restorative dental treatment. This is best accomplished by mounting accurate diagnostic casts on an articulator (Fig. 3) by using a face-bow and a verifiable centric relation record to determine the degree and location of the interfering cusps. When a diagnostic equilibrationI is done on the dental stone casts, the final result can be analyzed before any enamel is removed in the mouth.‘5~2*~4’,42 Many materials and carrying media (Figs. 4 and 5) are advocated for recording and transferring centric relation to an articulator.‘, 2,6,“s 2’*24,45-47Clutch frames, bite frames (Fig. 4)‘9,24,46face-bow forks, impression compound, hard wide portions of wax (Fig. 5),“’ and central bearing plates actually produce posterior interferences. Dental impression compound, plaster,24s46denDECEMBER
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Fig. 2. A, Commercially available plastic leaf gauge with numbered leaves (Huffman Leaf Gauges, Columbus, Ohio). B, Disposable paper leaf gauge booklet (right) designed by Dr. Woelfel and four different thicknesses of leaf gauges that have been separated from a booklet. As shown in Fig. 8, each color designates a specific thickness in increments of 0.5 mm. C, Leaf gauge properly angled between incisors. Mnimal separation of posterior teeth is required to permit physiologic reorientation of temporomandibular joints.
Fig. 3. Above, Hand-occluded casts of a 24year-old man who had experienced trismus and limited maximal incisor opening (35 mm) for 2 years. He was also unable to incise food except with canines. After wearing a maxillary occlusal splint with an anterior ramp for 15 months, his jaw stabilized in a more posterior position, as seen below. Belot, A centric relation mounting made with a 5.8 mm leaf gauge anteriorly to barely prevent grossly premature contact of mesiolingual cusp of upper left second molar with mesiobuccal cusp on mandibular molar. This relationship could not be corrected by an equilibration or by making eight molar crowns. Patient elected to 2 years of orthodontic treatment instead of oral surgery. His treatment was successful in achieving a harmony between centric relation and centric occlusion with incisor coupling and normal incisor opening (50 mm).
tal stone, zine oxide-eugenol paste,“, 19,“3 *Z 24,45,46 polysulfide rubber-,45 silicone rubber,45,47 polyether rubber45B48 (Fig. 6), self-activating acrylic resin,46 dental cement, and many varieties of wax have been used as recording THE JOURNAL
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media. These materials are sometimes carried to the mouth with a jig,’ a metal’P~“~46 or plastic frame holding thin gauze, fiberglass formulator mesh,“,2’ or polyahelene sheet (Fig. 4, B). Other carriers such as a bite fork, 717
WOELFEL
Fig. 4. Four types of frames designed for recording centric relation. A, coat hanger wire bent with a pliers supporting formulator mesh (0.17 mm thick) that is held only with soft wax; B, Freese frame (Odontic Co., Columbus, Ohio) a wire frame with straight sides onto which a preformed polyethylene sheet (0.02 mm thick) is securely held by two pockets that slide over the wire; C, Coe (Coe Laboratories, Inc. Chicago, Ill.) plastic bite frame, which adjusts to three arch widths by snapping the handle together. Thin gauze (0.06 mm thick) is supported by the posterior curved plastic arms; D, the Jones bite frame (Kerr Mfg. Co. Romulus, Mich.), is metal and has a lock screw anteriorly for arch width of posterior segments. Preformed cloth gauze squares (0.23 mm thick) each have a pocket that slides over open lingual wire frame with free edge extending buccally over other wire.
a soft metal” or wax sheet (Fig. 5),11~21~24~45 and modeling compound, have been advocated. Materials may be applied directly on the teeth with a tongue blade or cement spatula. Most of the carriers are bulky, clumsy, and cumbersome to use, seem messy and uncomfortable to the patient, and often provide substantial barriers for accurate closure of the jaw in the terminal hinge position (Figs. 4 and 5). Millstein et a1.36stated, “The interocclusal record is the most critical record obtained in restorative dentistry.” An accurate centric relation record must be as thin as possible: 2’ yet devoid of any posterior tooth contacts or interferences.9, “s 12,21,34,“3 42
Fig. 5. Four types of frameless carrying vehicles: A, Panadent (Panadent Corp., Grand Terrace, Calif.) metal wafer (0.36 mm thick); 5, Double thickness Moyco 56590 (J. B. Moyer Co., Philadelphia, Pa.) pink wax with tinfoil between layers (3.0 mm thick); C, Coprwax bite wafer (Columbus Dental Manufacturing, St. Louis, MO.) with tinfoil in middle (4.8 mm thick); D, Aluwax (Aluwax Dental Products, Grand Rapids, Mich.) waxed cloth forms (1.8 mm thick) with gauze in middle. 718
The new centric relation system to be describedis free from all of the previously listed problems. A thin flexible wafer (Fig. 7), is quickly customized. Used with its leaf gauge (Figs. 8, 9, and 10, A), it helps to guide the jaw posteriorly20 and to maintain the desired minimum vertical opening. l2 Maintaining the correct vertical separation in centric relation registrations is a common problem. 9,11This System is accurate, ineXpSiVej and adaptable to most occlusal relationships (Figs. 7 through 15). The material and device used are pleasant for the patient and serve as an aid in accurately mounting the casts (Fig. 14). DECEMBER
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Fig. 6. A, Leaf wafer assembly with polyether check-bite medium (Ramitec, Premier Co., Norristown, Pa.) is held in place correctly as patient maintains firm (not forceful) closure on leaf gauge until material is sufficiently set to permit removal without distortion (60 to 90 seconds). B, Side view of polyether check-bite made with pink 2M mm leaf gauge. C, Superior aspect of three polyether check-bites made on same patient by using different wafer configurations and varied-thickness leaf gauges. Apparent cusp penetrations to surface of wafer do not indicate unwanted opposing tooth contact but merely that the freely floating wafer is touching some of the maxillary posterior cusps (see insert in Fig. 13).
Fig. 7. O.S.U. Woelfel leaf wafer configuration and thicknesses. Three shapes are made in four thicknesses (cross-section of wafer C shown above). Wafer design A is useful in enormous dentition, centers itself, and is adaptable for use with Lucia jig (Fig. 1 and 15). Wafer B is for very broad arches, centers itself, and can be used for lateral check-bites. Wafer C is a nearly universal size and shape. Rich wafer consists of an inner index-card type material covered on each side by a 3%micrometer layer of Mylar. THE JOURNAL
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719
Fig. 8. Above, Disposable paper leaf-gauge booklet bound on one end. Ten groups color coded pages are arranged to designate a specific thickness from 0.5 mm (cherry) 5 mm (salmon) by increments of 0.5 mm. Brackets indicate additional thicknesses combining adjacent color groups. Below, technique used to separate desired thickness leaf gauge from booklet to @reserve bound end. 720
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Fig. 9. A, Patient’s head is tipped back to stretch anterior neck muscukture while closing on a leaf gauge that is inclined toward palate (30 to 40 degrees above occlusal plane). B, Sharp knife is used to separate one or two of perforations on each side of slot. Tab is bent downward away from printing. Maxillary incisors contact wafer directly anterior to this slot. C, Inserting paper leaf gauge into wafer from below (no printing). Note that tab is bent downward lingual to leaf gauge. Lower incisors contact this tab. Thus, anterior portion of wafer compensates for its thickness twice to ensure sufficient clearance posteriorly for check-bite material and wafer.
Fig. 10. A, Wafer is positioned according to closure on preselected leaf gauge within slot while midline and labial edge of maxillary incisors :is marked. B, Leaf gauge is removed from marked wafer. Excess length or width can be trimmed with a scissors at this time. C, Wafer alone is replaced in mouth, oriented by marks made in A, and patient closes firmly in centric occlusion, deforming wafer as shown in Fig. 11.
The new system, the O.S.U. Woelfel Leaf Wafer,* uses a thin (0.15 to 0.32 mm), anatomically-shaped, *Filed with United States Patent and Trademark 1985, and assigned serial No. 742,760. THE JOURNAL
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Office, June 10,
partially perforated paper card (Fig. 7) laminated on both sides with 0.0015 inch Mylar (DuPont Co., Wilmington, Del.). The blue wafer (Fig. 7) is 20 micxvmeters thinner than formulator mesh (Fig. 4, A>.‘9,24Each wafer has a combination slot handle for hokiing a new 721
WOELFEL
Fig. 11. Wafer as deformed by centric occlusion closure (Fig. 10, C): A, Upper surface; B, inferior surface; C, side-view; D, left, wafer before custom conforming of its occlusal surface (A, B, C), removed leaf gauge above, and cuspal indentations on deformed wafer (righf). E, leaf gauge (D center) is reinserted into custom conformed and air-dried wafer, which is then ready to have check-bite medium placed over these cuspal indentations.
type of narrow disposable leaf gauge of the appropriate thickness (Figs. 2, B, and 8). The slot tab, when bent down (Figs. 9, C and 10, B), provides the necessary vertical separation for the wafer posteriorly in addition to the amount produced by the leaf gauge. The recording media used is at the discretion of the dentist. The author’s first choice is polyether (Fig. 6).‘*,“’ The next best material is zinc oxide-eugenol paste,“, I992’,24,45,46 which requires the use of a polyether tray adhesive.
SEQUENTIAL PROCEDURES AND TECHNIQUE Before centric relation is recorded, a determination is made with a leaf gauge of the minimum incisor separation necessary to prevent posterior tooth contact and thus negate an adaptive closure pattern (engram).‘“~ ‘*****26 The incisors will usually be apart 1 to 3 mm when the occlusal prematurities are barely separated (Figs. 2, C and 13). Their separation is mandatory so that the proprioceptors in the peridontal ligaments of the prematurely contacting teeth will not, by reflex (engram), 722
adaptively guide the mandible into the undesired centric ~clusion psition.“s 1%15, 21s 349 * The patient’s head is tipped back (Figs. 2, C and 9, A) to stretch the suprahyoid and infrahyoid muscles.3*‘, ‘*, ‘S “-19 A leaf gauge of predetermined appropriate thickness paper is inserted in the slot of the wafer (Fig. 9, B and c> and both are positioned in the mouth so that the leaf gauge is centered at a 45-degree posterior upward slope between the incisors (Fig. 10, A). The patient is instructed to close in the back and hold the leaf gauge firmly. A felt marker or sharp explorer is used to mark the midline and labial extent of the maxillary incisors on the top side of the wafer (Fig. 10, A). Once it is removed, excess width or posterior length is trimmed off the wafer with a scissors while the patient is instructed again to tip the head back and keep the teeth apart. The leaf gauge is removed from its slot (Fig. 10, B), the wafer alone is again placed in the mouth,
*Regenos J, Wilkes R: Personal communication, 1984. DECEMBER
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Fig. 12. A thin layer of check-bite medium (polyether or zinc oxide-eugenol) is quickly spread over cuspally indented regions of wafer (Fig. 11). Anterior portion of wafer and lower surface of leaf gauge provide a clean secure handle for positioning assembly in mouth (Fig. 6, A).
loaded
Tongue
Fig. 13. Inferior view of check-bite (leff) and enlarged cross-sectional view of minimally separated opposing cusps with custom deformed wafer floating freely although nearly touching mandibular buccal and maxillary lingual cusps. This selected and necessary
separation of posterior teeth is maintained by leaf gauge thickness between incisors, supplemented
by wafer handle and tab thickness
oriented by the marks, and stabilized while the patient closes firmly in centric occlusion (Fig. 10, C). Because the Mylar-covered wafer is soft internally, its flat shape readily deforms to all irregularities in the oeelusal plane (Figs. 11 and 15, B, C, and 0). The cuspal indentations on the wafer (Fig. 11) show exactly where to apply the check-bite medium (Fig. 12) once the moisture is removed and the leaf gauge has been reinserted into the slot (Fig. 11, E). The patient should be &sing gently on an additional leaf gauge, cotton i-o&‘2 or saliva ejector to keep the teeth THEJ~URNALOFPR~~TH~ICDENTISTRY
(Fig. 9, B and C legend).
separated while the small quantity of cheek-bite medium (20 mm strips) is being mixed. The recording medium is quickly divided into four portions and applied on both sides of the wafer (Fig. 12), covering the centric occlusion indentations (Fig. 11). The wafer-leaf gauge assembly is then positioned in the mouth according to the midline and in&al edge mark (Figs. 6, A and 10, A) and the dentist guides the mandible until the lower incisor engages the tab on the wafer beneath the leaf gauge (Fig. 9, C). The patient is instructed to close and hold firmly until further notice (Fig. 6, A). 723
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Fig. 14. Maxillary cast, previously mounted is securely and accurately oriented to mandibular cast in centric relation position with entire leaf wafer check-bite assembly interposed between occlusal and incisal surfaces. Sticky wax is mandatory to maintain relationship while mounting mandibular cast.
The leaf wafer assembly and technique maintain the desired vertical dimension and retruded jaw position without tooth interference (insert, Fig. 13) while the check-bite media sets. The entire record is removed in one piece (Figs. 6, B and C, and 13) and inspected for accuracy, recording of the necessary tooth indentations, and lack of any opposing tooth contacts (rarely found). The properly trimmed, bubble-free opposing casts are assembled into the check-bite and inspected for complete seating with the slightly indented leaf gauge intentionally left in place while the sticky wax is applied, to give extra anterior stability during the mounting of the mandibular cast (Fig. 14). If a duplicate centric relation record is desired, a second wafer is trimmed and marked exactly as the first one or copied from it and occlusally indented from a centric occlusion closure without the leaf gauge (Fig. 10, C). The same thickness of color-coded paper leaf gauge (Figs. 2, B, 8, and 11, D) is then inserted (Fig. 11, E), and the recording medium is applied. Modification of one of the large wafers for use with an anterior acrylic resimjig is seen in Fig. 15. Storage of any type of recording medium for more than 15 minutes is undesirable because of shinkage, warpage, or with zinc oxide-eugenol, its brittle nature. 724
Fig. 15. Modification of one of the wafers (Fig. 7, A) for use with a Lucia jig (Figs. 1 and 15, A).7,11~18,21 A, Left, portion to be cut out is drawn; right, Lucia jig (palatal side down) rests on upper side of modified wafer. B, C, and D, show superior, inferior, and side view of wafer after patient closed on it in centric occlusion without the Lucia jig. Midline of maxillary incisors was marked on handle while patient closed on wafer. Portion of wafer distal to cuspal indentations can be trimmed with a scissors. Checkbite medium is applied directly over these irregularities on both sides, Lucia jig is replaced, and wafer is oriented according to midline mark (B and D) as patient closes firmly on lingual slope of acrylic resin jig (Fig. 1).
The advantages of this new leaf wafer technique are summarized in Table I. For lateral and protrusive excursive records, the O&U. Woelfel leaf wafer is used primarily to carry the check-bite medium without a leaf gauge. A wide wafer (Fig. 7, A and B) is first centered against the maxillary teeth and then indented by the cusps, with the mandible in the appropriate eccentric jaw position. The exact amount of jaw excursion” is controlled for the check-bite as well as learning from the tooth indentations (similar to Figs. 11 and 15) where the main quantity of recording medium should be applied. A brief description of the use of a leaf gauge and the advantages to be gained by its use is included in this article because of the integral role of the leaf wafer and to add clarity to its entire realm of usefulness. Only the color coding, disposable type, and narrower width leaves DECEMBER
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Table I. Advantages of O.S.U. Woelfel leaf wafer technique anatomically designed, accurate, easy to use, self-contained unit, readily adaptable to varied situations, mouths, and dentists’ needs. 2. Wafers are made in three shapes, four thicknesses (one thinner than formulator mesh), and are easy to modify with scissors and %I inch paper punch (Fig. 7). 3. Disposable, narrow, firm, color-coded leaf gauges (Fig. 8) guide and hold the mandible naturally in centric relation at the desired vertical separation of the tee&%X, 22.14
Table II. Using leaf gauge between incisors: Equivalent first molar separation (mm)*
1. Economical,
4. Eliminates sterilization delays, bite frame interferences, use of fiberglass mesh@,*” (Fig. 4, A), and gagging problems. 5. Laminated surface wafer readily conforms to irregularities in the occlusal plane (Figs. 11 and 15) and compensates for its own thickness anteriorly as it floats freely between the minimally separated opposing cusps (Fig. 13). 6. Duplicate centric relation check-bites’* are easily made by using exactly the same type of wafer and thickness of leaf gauge. 7. Lateral and protrusive check-bites can be made with the wafer, which is custom indented at the desired jaw position, thus showing exactly where to load the checkbite material. 8. Additional stability during mounting casts is achieved by leaving paper leaf gauge in the wafer assembly (Fig. 14). 9. The disposable leaf gauge can be given to patients to close on periodically for short periods of time as instructed to possibly alleviate temporomandibular joint pain caused by spasms of the superior heads of the lateral pterygoid muscles.“~” 10. The color-coded varied thickness leaf gauge (Fig. 8) facilitates wider use of this valuable diagnostic aid for patient records during orthodontic treatment and for adjustments of minor centric relation prematurities.
are innovations by the author. Numerous authors’O320,2b.4’*42s 44 and The American Academy of Restorative Dentistry43 have recognized the value of a leaf gauge diagnostically and how it deprograms cuspguided closures and guides the condyles neuromuscularly into their most superior position.20 Table II lists the exact amounts of opening for the incisor and first molar regions for reference while using any leaf but can be used as a guide when a gauge,10~21~22~26~4’-43 certain amount of molar separation is desired or to indicate how far apart the opposing first molars would be when a given thickness of leaf gauge or anterior jig is in place.
Using a leaf gauge 1. Predetermine the approximate magnitude of centric relation-centric occlusion error, for instance, a severe slide forward or to one side,2’ a slight hit and slide, or no apparent discrepancy. THE JOURNAL
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0.05 1 .o I.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 1.36 2.72 4.07 5.4:3 6.79
0.37 0.74 1.10 1.47 1.84 2.21 2.58 2.95 3.31 3.68 1.00 2.00 3.00 4.00 5.00
‘Data derived from reference Nos. 39 and 49.
2. Place sufiicient leaves between the upper and lower incisors at a 45-dtgree aregulation toward the palate (Figs. 2, C and 10, A) to prevent p&or tooth contact. Verify this by asking the patient iF any teeth are touching. If so, add several more leaves. Each time, the patient should retrude the jaw and dose until the incisors touch the leaf gauge. The closure should the? be held firmly. 3. Wait 30 seconds or longer to make sure that one or more posterior teeth do not come into contact’5~‘9.2’*26~28 ‘*.” as a result of shift or relaxation in the musculature and joints. If the patient does feel a tooth touch, add several more leaves and wait an additional minute. 4. For centric registration procedures, the vertical dimension should be opened by the leaf gauge 2 to 4 leaves beyond the first premature tooth contact (margin of error). 5. For adjustment of premature tooth contact, two plastic or three paper leaves are removed each time until the patient notices the first tooth contac?” “. 2*.“.*2 while tapping on the leaf gauge several times with the jaw retruded. This premature tooth contact can be tested for verification with shim stock (The Artus Corp., Englewood, N.J.) or can be marked with articulating Mylar or located with soft thin occlusal wax interposed on the offending side as the incisors close on the leaf gauge. 6. After the first prematurity is eliminated (through grinding on the appropriate cusp slope or incline), remove one or more leaves until another tooth touches. Verify and mark this tooth, with the patient again tapping on the leaf gauge while you place articulating Mylar held with a MiIler forceps or thin wax on the side of the interference. This process is continued until several posterior teeth on each side will simultaneously 725
hold shim stock with the minimal thickness leaf gauge in place. The leaf gauge is ineffective in prognathic relationships and it may be necessary to use a very thick one (5 to 8 mm) in severe malocclusion (Fig. 3) and in retrognathic relationships. When a large error in centric relation to centric occlusion (more than 2% mm of incisor separation as in Fig. 3), is discovered by using the leaf gauge, it may not be possible to eliminate the discrepancies without some orthodontic treatment, placement of several crowns or onlays, or surgical intervention. The leaf gauge is an invaluable aid in equally distributing centric relation contacts between natural teeth and works well with distal-extension removable partial dentures. A leaf gauge may also be used to measure for adequate occlusal tooth reduction during full line crown preparations.
Significant
advalitages of a leaf gauge
1. The patient’s own musculature seats the condyles into centric relation, thus avoiding the need for manipulation by the dentist.12s‘O,28,35 2. Periodontal ligament proprioception is eliminated
*A very similar device, the Buhnergraph, 44.
prematu~ty*ll,
12,21,28,34
4. Firm incisor contact on the leaf gauge continually for 1 to 5 minutes may allow jaw muscle relaxation, sometimes relieving pain and usually permitting the jaw to retrude naturally, assuming a more comfortable position. 10,15,20-22,26,41-43
SUMMARY AND CONCLUSION A new system for recording jaw relations has been described. It is easy to learn to use correctly, is pieasant to the patient while assisting the patient’s neuromusculature into the desired retruded closure at the specific vertical dimension preselected by the dentist, and it uses minimal amounts of recording media. Duplicate records can be quickly made for verification, various recording media may be used, improved stability during mounting is obtained, and the method is applicable in most dentulous and partially edentulous situations. Two elements are used, a dental arch-shaped, partially perforated, thin, waterproof wafer and a disposable paper leaf gauge. The paper leaf gauge is narrower and more solid than the plastic leaf gauge and thus forms a better anterior leg of the tripod with the two condyles on patient-guided terminal hinge closures.9s“3 24 The leaf gauge of preselected thickness is inserted into a slot in the wafer that has been deformed exactly like the occlusal plane by a previous centric occlusion closure. The system
is described in reference
REFERENCES 1. 2.
3. 4. 5. 6. 7. 8.
11,G 15,31,34
3. Patient concentrates biting toward or onto the leaf gauge, not toward the side where the articulating paper or wax is placed or by reflex action away from the
726
is quick, economical, and less complex than most methods presently used. Even so, it accurately reproduced six check-bites on one patient according to comparisons on the Veri-check instrument (Denar Corp., Anaheim, Calif.).*
9. 10. 11. 12. 13. 14. 15.
16.
17. 18. 19. 20.
21.
22.
23.
Boos RH: Vertical, centric and functional dimensions recorded by gnathodynamics. J Am Dent Assoc 59~682, 1959. Mann AW, Pankey LD: Concepts of occlusion-the P-M philosophy of occlusal rehabilitation. Dent Clin North Am 7:621, 1963. Stuart CE: Oral Rehabilitation and Occlusion. San Francisco, 1972, University of California, vol 1 and 4. McCollum BB, Stuart CE: A Research Report. Ventura, Calif, 1955, Scientific Press. Posselt U: The Physiology of Occlusion and Rehabilitation. Philadelphia, 1962, FA Davis Co. DePietro AJ: Concepts of occlusion-a system based on rotational centers of the mandible. Dent Clin North Am 7:607, 1963. Lucia VO: A technique for recording centric relation. J PROSTHET DENT 14~492, 1964. El-Aramany MA, George AW, Scott RH: Evaluating the needle-point tracing as a method for determining centric relation. J PROSTHET DENT 15~1043, 1965. Wirth CG, Aplin AW: An improved interocclusal record for centric relation. J PROSTHET DENT 25279, 1971. Long JH: Locating centric relation with a leaf gauge. J PROSTHET DENT 29:608, 1973. Kornfield M: Mouth Rehabilitation. Clinical and Laboratory Procedures, ed 2. St Louis, 1974, The CV Mosby Co. Dawson PE: Evaluation, Diagnosis, and Treatment of Occlusal Problems. St Louis, 1974, The CV Mosby Co, pp 48-70. The Denar Mark II System-Technique Manual. Anaheim, Calif, 1975, Denar Corporation. Mahan PE: The Physiology of Occlusion, Clinical Dentistry. Hagerstown, 1977, Harper & Row Publishers Inc, vol 2. Guichet NF: Biologic laws governing functions of muscles that move the mandible: Part I: Occlusal programming. J PROSTHET DENT 37:648, 1977. Lundeen HC, Shrvock EF. Gibbs CH: An evaluation of mandibular border movements-Their character and significance. J PROSTHET DENT 40~442, 1978. Dawson PE: Centric relation: Its effect on occlusomuscle harmony. Dent Clin North Am 23~169, 1979. Lucia VO: Principles of articulation. Dent Clin North Am 23~199, 1979. Huffman RW, Regenos JW, Taylor RR: Principles of Occlusion, ed 8. Columbus, Ohio, 1980, H & R Press. Williamson EH, Steinke RM, Morse PK, Swift TR: Centric relation-A comparison of muscle determined position and operator guidance. Am J Orthod 77~133, 1980. Wise MD: Occlusion and restorative dentistry for the general practitioner. London, 1982, Professional Scientific Publications Ltd BMA House. Williamson EH: The role of craniomandibular dysfunction in orthodontic diagnosis and treatment planning. Dent Clin North Am 27~531, 1983. Atwood DA: A critique of research of the posterior limit of the mandibular position. J PROSTHET DENT 20~21, 1965. DECEMBER
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24.
Strohaver RA: A comparison of articulator mountings made with centric relation and myocentric position records. J PROSTHET DENT 28~379, 1972. 25. Mongini F: Anatomic and clinical evaluation of the relationship between the temporomandibular joint and occlusion. J PROSTHET DENT 38:539, 1977. 26. McHorris WH: Gnathological Conference presentation. Columbus, Ohio, April 25, 1985. 27. Guichet NF: Biologic laws governing functions of muscles that move the mandible. Part IV: Degree of jaw separation and potential for maximum jaw separation. J PROSTHET DENT 38:310, 1977. 28. Martel MH: When-why-how to ad,just occlusion. Report 2129, Quintessence Int 19:933, 1982. 29. Gibbs CH, Lundeen HC, Mahan PE, Fujimoto J: Chewing movements in relation to border movements at the first molar. J PROSTHET DENT 46:308,
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Clayton JA, Crispin BJ, Shields JM, Myers GE: A pantographic reproducibility index (PRI) for detection of TMJ dysfunction. J Dent Res 55~161, 1976. Posselt 17: An analyzer for mandibular positions. J PROSTHET
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Woelfel JB: Dental Anatomy: Its Correlation with Dental Health Sel*vice, ed 3. Philadelphia, 1984, I,ea & Febiger, pp 296, 341, 348, 365. Lederman KH, Clayton JA: Patients with restored occlusions. Part III: The effect of occlusal splint therapy and occlusal adjustments on TMJ dysfunction. .J PXOSTHE'TDEKT 50:95, 1983. Shankland WE, Ralston SJ: The fabrication and use of a leaf gauge to locate centric relation. Ohio Dent .J 57~43. 1983. Golsen LF, Shaw AF: Use of leaf gauge in diagnosis and therapy. Quintessence Int 6:611, 1984. Phillips RW, Hamilton IA, Jendresen MD, McHorris WH, Schallhorrl RG: Report of the Committee on Scientific tnvesrigation of the American Academy of Restorative Dentistry. ~J PROSTHET DENT 53:844,
1985.
Long JH: Location of the terminal hinge avis by intraoral means. J PROSTHW DENT 23~11, 1970. 45. Mullick SC, Stackhouse JA, Vincent GR: A study of inten,c.c.lusal record materials. J PROSTHEX DENT 4S:304, 1981. 46. Skurnik H: Accurate interocclusal rccord~. J PROSTHET DEWI 44.
21:154.
1969.
47.
1957.
Stuart CE: The contributions of gnathology to prosthodontics. J PRWTHET DENT 30~607, 1973. McMillen LB: Border movements of the human mandible. J PROSTHET DENT 27:524,
39.
1972.
34.
Guichet NF: Applied gnathology: Why and how. Dent Clin North Am 13:687, 1969. 35. Wirth CH, Aplin AW: An improved interocclusal record for centric relation. J PROSTHET DENT 25:279, 1971. 36. Millstein PL, Kronman JH, Clark RE: Hydroptic measuring system for testing the accuracy of interocclusal recording mediums. J Dent Res 49~462, 1970. 37. Williamson EH, Evans DL, Barton WA, Williams BH: The effect of bite plane use on terminal hinge axis location. Angle Orthod 47:25, 1977. 38. Shankland WE: Biteplane therapy: Theory and fabrication. Ohio Dent J 54:40, 1980.
Millstein I?L, Clark RE, Myerson RL: Differential accuracy of silicone-body interocclusal records and associated weight loss due to volatile:. J PROSTHETDENT 33:649, 19'5. 48. Lassila V: Comparison of five interocclusal recording materials. J PROSTHETDENT. 55:215,1986. 49. Woelfel JB, Igarashi T, Winter CM’: Increase in vertical dimension caused by gnathological clutches. ,J Dent Res 50(Special issue): 163, 197 1 (Abstr No. 44 1.
&pm
reque.rtJ to:
DR. JULIAN B. WOELFEL
OHIO STATE UNIVERSITY COLLEGEOF DENTISTRY COLUMBIT. OH 41210
ch to the dif#krmtM
d
Terry T. Tanaka, D.D.S.* University of California, San Diego, Medical Center, San Diego, Calif.
R
heumatologic diseases present major diagnostic and management challenges to the dentist treating temporomandibular joint (TMJ) disorders. Because of their chronicity, variability of symptoms, and tendency to Presented at the Pacific Coast Society of Prosthodontists, Vancouver, B.C., Canada. *Associate Clinical Professor, Department of Surgery, School of Medicine; Director, Facial Pain and TMJ Clinic. THE JOURNAL
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painfully exacerbate and remit, the complexity of these disorders can confuse and frustrate the patient and the dentist. Successful managment requires understanding and differentiation of these disorders early in the diagnostic process. The ability to separate signs and symptoms and assign importance to their relative ciinkal significance is called differential diagnosis. Experience at the Facial Pain Clinic at the University 727
FUNCTION
AND DYSFUNCTION
SECTION EDITOR
GEORGE A. ZARB
New device for accurately
recording
centric relation
J. B. Woelfel, D.D.S.* Ohio State University, College of Dentistry, Columbus, Ohio
D
entists have used many methods and devices in an attempt to precisely locate and record the centric relation position of the mandible.lTz2 No single method has become universally accepted23-26although several techniques have achieved varying degrees of popularity. These include needlepoint tracing devices*; holding the tip of the tongue back in the soft palate; telling the patient to swallow while closing; having the patient pull the lower jaw back24or “stick the upper jaw out;” having the patient relax the mandible and let the dentist manipulate it upward and posteriorly’s “a 12,21,27,28; and telling the patient to relax and close naturally.24 More precise but less popular methods use clutches and a pantographic recording of mandibular border movements 3-5*“2 ‘6,29-33 an acrylic resin jig (Lucia jig)‘, ‘I, ‘8,2’ (Fig. ;), cotton ro11,12tongue blade,‘O popsickle stick,2’,24 narrow strip of soft metal,9*1’*24firtn wax,2’ or a leaf gauge anteriorly (Fig. 2) to exert an upward and posterior guidance during closure.1° The least accurate and most unreliable methods are the functional chewin,2p34the use of electromyographic recording, the MyoMonitor (Myo-tronics Research, Seattle, Wash.),24 Boos power points (Boos Dental Laboratory, Minneapolis, Minn.), True-Centric device (Ticonium Co., Albany, N.Y.), and others. Neuromuscular relaxation is an integral part of a physiologically sound and scientific recording method. Patients can be conditioned by wearing an acrylic resin maxillary occlusal splint (bite plane) for a short time, or until the mandible has assumed a stable comfortable position before making a centric relation jaw registration.6s“9 I932’,33,35-39This applies to different types of prosthodontic treatment. 19,2’,28,39*4o Otherwise, the dentist should at least determine the extent of occlusal discrepancies in mandibular dysfunction patients by testing the existent occlusal error by means of a leaf gauge. ‘“,22,26*4’-44 Research has shown that when a patient bites firmly on a leaf gauge between the incisors, the condyles appear to seat in the most superior and comfortable posterior position.20 This narrow anterior vertical stop forms a tripod effect between the anterior teeth and the condyles9F”,24 as the patient’s closing musculature functions freely without conflicting proprioceptive guidance caused by deflective tooth contacts.“, I2915,2’, 34,45Observing, recording, and eliminating undesirable tooth interferences is dependent on precise *Professor, Division of Prosthodontics.
716
Fig. 1. Front and side views of Lucia jig, which increases vertical dimension minimally. It provides a narrow ramp inclined toward palate. Mandible is guided posteriorly as lower incisors slide easily on ramp.
and repeatable neuromuscularly relaxed closures of the mandible in the centric relation arc. It is of paramount importance that existing occlusal discrepancies be eliminated before, or in conjunction with, any relatively extensive restorative dental treatment. This is best accomplished by mounting accurate diagnostic casts on an articulator (Fig. 3) by using a face-bow and a verifiable centric relation record to determine the degree and location of the interfering cusps. When a diagnostic equilibrationI is done on the dental stone casts, the final result can be analyzed before any enamel is removed in the mouth.‘5~2*~4’,42 Many materials and carrying media (Figs. 4 and 5) are advocated for recording and transferring centric relation to an articulator.‘, 2,6,“s 2’*24,45-47Clutch frames, bite frames (Fig. 4)‘9,24,46face-bow forks, impression compound, hard wide portions of wax (Fig. 5),“’ and central bearing plates actually produce posterior interferences. Dental impression compound, plaster,24s46denDECEMBER
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Fig. 2. A, Commercially available plastic leaf gauge with numbered leaves (Huffman Leaf Gauges, Columbus, Ohio). B, Disposable paper leaf gauge booklet (right) designed by Dr. Woelfel and four different thicknesses of leaf gauges that have been separated from a booklet. As shown in Fig. 8, each color designates a specific thickness in increments of 0.5 mm. C, Leaf gauge properly angled between incisors. Mnimal separation of posterior teeth is required to permit physiologic reorientation of temporomandibular joints.
Fig. 3. Above, Hand-occluded casts of a 24year-old man who had experienced trismus and limited maximal incisor opening (35 mm) for 2 years. He was also unable to incise food except with canines. After wearing a maxillary occlusal splint with an anterior ramp for 15 months, his jaw stabilized in a more posterior position, as seen below. Belot, A centric relation mounting made with a 5.8 mm leaf gauge anteriorly to barely prevent grossly premature contact of mesiolingual cusp of upper left second molar with mesiobuccal cusp on mandibular molar. This relationship could not be corrected by an equilibration or by making eight molar crowns. Patient elected to 2 years of orthodontic treatment instead of oral surgery. His treatment was successful in achieving a harmony between centric relation and centric occlusion with incisor coupling and normal incisor opening (50 mm).
tal stone, zine oxide-eugenol paste,“, 19,“3 *Z 24,45,46 polysulfide rubber-,45 silicone rubber,45,47 polyether rubber45B48 (Fig. 6), self-activating acrylic resin,46 dental cement, and many varieties of wax have been used as recording THE JOURNAL
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media. These materials are sometimes carried to the mouth with a jig,’ a metal’P~“~46 or plastic frame holding thin gauze, fiberglass formulator mesh,“,2’ or polyahelene sheet (Fig. 4, B). Other carriers such as a bite fork, 717
WOELFEL
Fig. 4. Four types of frames designed for recording centric relation. A, coat hanger wire bent with a pliers supporting formulator mesh (0.17 mm thick) that is held only with soft wax; B, Freese frame (Odontic Co., Columbus, Ohio) a wire frame with straight sides onto which a preformed polyethylene sheet (0.02 mm thick) is securely held by two pockets that slide over the wire; C, Coe (Coe Laboratories, Inc. Chicago, Ill.) plastic bite frame, which adjusts to three arch widths by snapping the handle together. Thin gauze (0.06 mm thick) is supported by the posterior curved plastic arms; D, the Jones bite frame (Kerr Mfg. Co. Romulus, Mich.), is metal and has a lock screw anteriorly for arch width of posterior segments. Preformed cloth gauze squares (0.23 mm thick) each have a pocket that slides over open lingual wire frame with free edge extending buccally over other wire.
a soft metal” or wax sheet (Fig. 5),11~21~24~45 and modeling compound, have been advocated. Materials may be applied directly on the teeth with a tongue blade or cement spatula. Most of the carriers are bulky, clumsy, and cumbersome to use, seem messy and uncomfortable to the patient, and often provide substantial barriers for accurate closure of the jaw in the terminal hinge position (Figs. 4 and 5). Millstein et a1.36stated, “The interocclusal record is the most critical record obtained in restorative dentistry.” An accurate centric relation record must be as thin as possible: 2’ yet devoid of any posterior tooth contacts or interferences.9, “s 12,21,34,“3 42
Fig. 5. Four types of frameless carrying vehicles: A, Panadent (Panadent Corp., Grand Terrace, Calif.) metal wafer (0.36 mm thick); 5, Double thickness Moyco 56590 (J. B. Moyer Co., Philadelphia, Pa.) pink wax with tinfoil between layers (3.0 mm thick); C, Coprwax bite wafer (Columbus Dental Manufacturing, St. Louis, MO.) with tinfoil in middle (4.8 mm thick); D, Aluwax (Aluwax Dental Products, Grand Rapids, Mich.) waxed cloth forms (1.8 mm thick) with gauze in middle. 718
The new centric relation system to be describedis free from all of the previously listed problems. A thin flexible wafer (Fig. 7), is quickly customized. Used with its leaf gauge (Figs. 8, 9, and 10, A), it helps to guide the jaw posteriorly20 and to maintain the desired minimum vertical opening. l2 Maintaining the correct vertical separation in centric relation registrations is a common problem. 9,11This System is accurate, ineXpSiVej and adaptable to most occlusal relationships (Figs. 7 through 15). The material and device used are pleasant for the patient and serve as an aid in accurately mounting the casts (Fig. 14). DECEMBER
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Fig. 6. A, Leaf wafer assembly with polyether check-bite medium (Ramitec, Premier Co., Norristown, Pa.) is held in place correctly as patient maintains firm (not forceful) closure on leaf gauge until material is sufficiently set to permit removal without distortion (60 to 90 seconds). B, Side view of polyether check-bite made with pink 2M mm leaf gauge. C, Superior aspect of three polyether check-bites made on same patient by using different wafer configurations and varied-thickness leaf gauges. Apparent cusp penetrations to surface of wafer do not indicate unwanted opposing tooth contact but merely that the freely floating wafer is touching some of the maxillary posterior cusps (see insert in Fig. 13).
Fig. 7. O.S.U. Woelfel leaf wafer configuration and thicknesses. Three shapes are made in four thicknesses (cross-section of wafer C shown above). Wafer design A is useful in enormous dentition, centers itself, and is adaptable for use with Lucia jig (Fig. 1 and 15). Wafer B is for very broad arches, centers itself, and can be used for lateral check-bites. Wafer C is a nearly universal size and shape. Rich wafer consists of an inner index-card type material covered on each side by a 3%micrometer layer of Mylar. THE JOURNAL
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719
Fig. 8. Above, Disposable paper leaf-gauge booklet bound on one end. Ten groups color coded pages are arranged to designate a specific thickness from 0.5 mm (cherry) 5 mm (salmon) by increments of 0.5 mm. Brackets indicate additional thicknesses combining adjacent color groups. Below, technique used to separate desired thickness leaf gauge from booklet to @reserve bound end. 720
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Fig. 9. A, Patient’s head is tipped back to stretch anterior neck muscukture while closing on a leaf gauge that is inclined toward palate (30 to 40 degrees above occlusal plane). B, Sharp knife is used to separate one or two of perforations on each side of slot. Tab is bent downward away from printing. Maxillary incisors contact wafer directly anterior to this slot. C, Inserting paper leaf gauge into wafer from below (no printing). Note that tab is bent downward lingual to leaf gauge. Lower incisors contact this tab. Thus, anterior portion of wafer compensates for its thickness twice to ensure sufficient clearance posteriorly for check-bite material and wafer.
Fig. 10. A, Wafer is positioned according to closure on preselected leaf gauge within slot while midline and labial edge of maxillary incisors :is marked. B, Leaf gauge is removed from marked wafer. Excess length or width can be trimmed with a scissors at this time. C, Wafer alone is replaced in mouth, oriented by marks made in A, and patient closes firmly in centric occlusion, deforming wafer as shown in Fig. 11.
The new system, the O.S.U. Woelfel Leaf Wafer,* uses a thin (0.15 to 0.32 mm), anatomically-shaped, *Filed with United States Patent and Trademark 1985, and assigned serial No. 742,760. THE JOURNAL
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Office, June 10,
partially perforated paper card (Fig. 7) laminated on both sides with 0.0015 inch Mylar (DuPont Co., Wilmington, Del.). The blue wafer (Fig. 7) is 20 micxvmeters thinner than formulator mesh (Fig. 4, A>.‘9,24Each wafer has a combination slot handle for hokiing a new 721
WOELFEL
Fig. 11. Wafer as deformed by centric occlusion closure (Fig. 10, C): A, Upper surface; B, inferior surface; C, side-view; D, left, wafer before custom conforming of its occlusal surface (A, B, C), removed leaf gauge above, and cuspal indentations on deformed wafer (righf). E, leaf gauge (D center) is reinserted into custom conformed and air-dried wafer, which is then ready to have check-bite medium placed over these cuspal indentations.
type of narrow disposable leaf gauge of the appropriate thickness (Figs. 2, B, and 8). The slot tab, when bent down (Figs. 9, C and 10, B), provides the necessary vertical separation for the wafer posteriorly in addition to the amount produced by the leaf gauge. The recording media used is at the discretion of the dentist. The author’s first choice is polyether (Fig. 6).‘*,“’ The next best material is zinc oxide-eugenol paste,“, I992’,24,45,46 which requires the use of a polyether tray adhesive.
SEQUENTIAL PROCEDURES AND TECHNIQUE Before centric relation is recorded, a determination is made with a leaf gauge of the minimum incisor separation necessary to prevent posterior tooth contact and thus negate an adaptive closure pattern (engram).‘“~ ‘*****26 The incisors will usually be apart 1 to 3 mm when the occlusal prematurities are barely separated (Figs. 2, C and 13). Their separation is mandatory so that the proprioceptors in the peridontal ligaments of the prematurely contacting teeth will not, by reflex (engram), 722
adaptively guide the mandible into the undesired centric ~clusion psition.“s 1%15, 21s 349 * The patient’s head is tipped back (Figs. 2, C and 9, A) to stretch the suprahyoid and infrahyoid muscles.3*‘, ‘*, ‘S “-19 A leaf gauge of predetermined appropriate thickness paper is inserted in the slot of the wafer (Fig. 9, B and c> and both are positioned in the mouth so that the leaf gauge is centered at a 45-degree posterior upward slope between the incisors (Fig. 10, A). The patient is instructed to close in the back and hold the leaf gauge firmly. A felt marker or sharp explorer is used to mark the midline and labial extent of the maxillary incisors on the top side of the wafer (Fig. 10, A). Once it is removed, excess width or posterior length is trimmed off the wafer with a scissors while the patient is instructed again to tip the head back and keep the teeth apart. The leaf gauge is removed from its slot (Fig. 10, B), the wafer alone is again placed in the mouth,
*Regenos J, Wilkes R: Personal communication, 1984. DECEMBER
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Fig. 12. A thin layer of check-bite medium (polyether or zinc oxide-eugenol) is quickly spread over cuspally indented regions of wafer (Fig. 11). Anterior portion of wafer and lower surface of leaf gauge provide a clean secure handle for positioning assembly in mouth (Fig. 6, A).
loaded
Tongue
Fig. 13. Inferior view of check-bite (leff) and enlarged cross-sectional view of minimally separated opposing cusps with custom deformed wafer floating freely although nearly touching mandibular buccal and maxillary lingual cusps. This selected and necessary
separation of posterior teeth is maintained by leaf gauge thickness between incisors, supplemented
by wafer handle and tab thickness
oriented by the marks, and stabilized while the patient closes firmly in centric occlusion (Fig. 10, C). Because the Mylar-covered wafer is soft internally, its flat shape readily deforms to all irregularities in the oeelusal plane (Figs. 11 and 15, B, C, and 0). The cuspal indentations on the wafer (Fig. 11) show exactly where to apply the check-bite medium (Fig. 12) once the moisture is removed and the leaf gauge has been reinserted into the slot (Fig. 11, E). The patient should be &sing gently on an additional leaf gauge, cotton i-o&‘2 or saliva ejector to keep the teeth THEJ~URNALOFPR~~TH~ICDENTISTRY
(Fig. 9, B and C legend).
separated while the small quantity of cheek-bite medium (20 mm strips) is being mixed. The recording medium is quickly divided into four portions and applied on both sides of the wafer (Fig. 12), covering the centric occlusion indentations (Fig. 11). The wafer-leaf gauge assembly is then positioned in the mouth according to the midline and in&al edge mark (Figs. 6, A and 10, A) and the dentist guides the mandible until the lower incisor engages the tab on the wafer beneath the leaf gauge (Fig. 9, C). The patient is instructed to close and hold firmly until further notice (Fig. 6, A). 723
WOELFEL
Fig. 14. Maxillary cast, previously mounted is securely and accurately oriented to mandibular cast in centric relation position with entire leaf wafer check-bite assembly interposed between occlusal and incisal surfaces. Sticky wax is mandatory to maintain relationship while mounting mandibular cast.
The leaf wafer assembly and technique maintain the desired vertical dimension and retruded jaw position without tooth interference (insert, Fig. 13) while the check-bite media sets. The entire record is removed in one piece (Figs. 6, B and C, and 13) and inspected for accuracy, recording of the necessary tooth indentations, and lack of any opposing tooth contacts (rarely found). The properly trimmed, bubble-free opposing casts are assembled into the check-bite and inspected for complete seating with the slightly indented leaf gauge intentionally left in place while the sticky wax is applied, to give extra anterior stability during the mounting of the mandibular cast (Fig. 14). If a duplicate centric relation record is desired, a second wafer is trimmed and marked exactly as the first one or copied from it and occlusally indented from a centric occlusion closure without the leaf gauge (Fig. 10, C). The same thickness of color-coded paper leaf gauge (Figs. 2, B, 8, and 11, D) is then inserted (Fig. 11, E), and the recording medium is applied. Modification of one of the large wafers for use with an anterior acrylic resimjig is seen in Fig. 15. Storage of any type of recording medium for more than 15 minutes is undesirable because of shinkage, warpage, or with zinc oxide-eugenol, its brittle nature. 724
Fig. 15. Modification of one of the wafers (Fig. 7, A) for use with a Lucia jig (Figs. 1 and 15, A).7,11~18,21 A, Left, portion to be cut out is drawn; right, Lucia jig (palatal side down) rests on upper side of modified wafer. B, C, and D, show superior, inferior, and side view of wafer after patient closed on it in centric occlusion without the Lucia jig. Midline of maxillary incisors was marked on handle while patient closed on wafer. Portion of wafer distal to cuspal indentations can be trimmed with a scissors. Checkbite medium is applied directly over these irregularities on both sides, Lucia jig is replaced, and wafer is oriented according to midline mark (B and D) as patient closes firmly on lingual slope of acrylic resin jig (Fig. 1).
The advantages of this new leaf wafer technique are summarized in Table I. For lateral and protrusive excursive records, the O&U. Woelfel leaf wafer is used primarily to carry the check-bite medium without a leaf gauge. A wide wafer (Fig. 7, A and B) is first centered against the maxillary teeth and then indented by the cusps, with the mandible in the appropriate eccentric jaw position. The exact amount of jaw excursion” is controlled for the check-bite as well as learning from the tooth indentations (similar to Figs. 11 and 15) where the main quantity of recording medium should be applied. A brief description of the use of a leaf gauge and the advantages to be gained by its use is included in this article because of the integral role of the leaf wafer and to add clarity to its entire realm of usefulness. Only the color coding, disposable type, and narrower width leaves DECEMBER
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Table I. Advantages of O.S.U. Woelfel leaf wafer technique anatomically designed, accurate, easy to use, self-contained unit, readily adaptable to varied situations, mouths, and dentists’ needs. 2. Wafers are made in three shapes, four thicknesses (one thinner than formulator mesh), and are easy to modify with scissors and %I inch paper punch (Fig. 7). 3. Disposable, narrow, firm, color-coded leaf gauges (Fig. 8) guide and hold the mandible naturally in centric relation at the desired vertical separation of the tee&%X, 22.14
Table II. Using leaf gauge between incisors: Equivalent first molar separation (mm)*
1. Economical,
4. Eliminates sterilization delays, bite frame interferences, use of fiberglass mesh@,*” (Fig. 4, A), and gagging problems. 5. Laminated surface wafer readily conforms to irregularities in the occlusal plane (Figs. 11 and 15) and compensates for its own thickness anteriorly as it floats freely between the minimally separated opposing cusps (Fig. 13). 6. Duplicate centric relation check-bites’* are easily made by using exactly the same type of wafer and thickness of leaf gauge. 7. Lateral and protrusive check-bites can be made with the wafer, which is custom indented at the desired jaw position, thus showing exactly where to load the checkbite material. 8. Additional stability during mounting casts is achieved by leaving paper leaf gauge in the wafer assembly (Fig. 14). 9. The disposable leaf gauge can be given to patients to close on periodically for short periods of time as instructed to possibly alleviate temporomandibular joint pain caused by spasms of the superior heads of the lateral pterygoid muscles.“~” 10. The color-coded varied thickness leaf gauge (Fig. 8) facilitates wider use of this valuable diagnostic aid for patient records during orthodontic treatment and for adjustments of minor centric relation prematurities.
are innovations by the author. Numerous authors’O320,2b.4’*42s 44 and The American Academy of Restorative Dentistry43 have recognized the value of a leaf gauge diagnostically and how it deprograms cuspguided closures and guides the condyles neuromuscularly into their most superior position.20 Table II lists the exact amounts of opening for the incisor and first molar regions for reference while using any leaf but can be used as a guide when a gauge,10~21~22~26~4’-43 certain amount of molar separation is desired or to indicate how far apart the opposing first molars would be when a given thickness of leaf gauge or anterior jig is in place.
Using a leaf gauge 1. Predetermine the approximate magnitude of centric relation-centric occlusion error, for instance, a severe slide forward or to one side,2’ a slight hit and slide, or no apparent discrepancy. THE JOURNAL
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0.05 1 .o I.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 1.36 2.72 4.07 5.4:3 6.79
0.37 0.74 1.10 1.47 1.84 2.21 2.58 2.95 3.31 3.68 1.00 2.00 3.00 4.00 5.00
‘Data derived from reference Nos. 39 and 49.
2. Place sufiicient leaves between the upper and lower incisors at a 45-dtgree aregulation toward the palate (Figs. 2, C and 10, A) to prevent p&or tooth contact. Verify this by asking the patient iF any teeth are touching. If so, add several more leaves. Each time, the patient should retrude the jaw and dose until the incisors touch the leaf gauge. The closure should the? be held firmly. 3. Wait 30 seconds or longer to make sure that one or more posterior teeth do not come into contact’5~‘9.2’*26~28 ‘*.” as a result of shift or relaxation in the musculature and joints. If the patient does feel a tooth touch, add several more leaves and wait an additional minute. 4. For centric registration procedures, the vertical dimension should be opened by the leaf gauge 2 to 4 leaves beyond the first premature tooth contact (margin of error). 5. For adjustment of premature tooth contact, two plastic or three paper leaves are removed each time until the patient notices the first tooth contac?” “. 2*.“.*2 while tapping on the leaf gauge several times with the jaw retruded. This premature tooth contact can be tested for verification with shim stock (The Artus Corp., Englewood, N.J.) or can be marked with articulating Mylar or located with soft thin occlusal wax interposed on the offending side as the incisors close on the leaf gauge. 6. After the first prematurity is eliminated (through grinding on the appropriate cusp slope or incline), remove one or more leaves until another tooth touches. Verify and mark this tooth, with the patient again tapping on the leaf gauge while you place articulating Mylar held with a MiIler forceps or thin wax on the side of the interference. This process is continued until several posterior teeth on each side will simultaneously 725
hold shim stock with the minimal thickness leaf gauge in place. The leaf gauge is ineffective in prognathic relationships and it may be necessary to use a very thick one (5 to 8 mm) in severe malocclusion (Fig. 3) and in retrognathic relationships. When a large error in centric relation to centric occlusion (more than 2% mm of incisor separation as in Fig. 3), is discovered by using the leaf gauge, it may not be possible to eliminate the discrepancies without some orthodontic treatment, placement of several crowns or onlays, or surgical intervention. The leaf gauge is an invaluable aid in equally distributing centric relation contacts between natural teeth and works well with distal-extension removable partial dentures. A leaf gauge may also be used to measure for adequate occlusal tooth reduction during full line crown preparations.
Significant
advalitages of a leaf gauge
1. The patient’s own musculature seats the condyles into centric relation, thus avoiding the need for manipulation by the dentist.12s‘O,28,35 2. Periodontal ligament proprioception is eliminated
*A very similar device, the Buhnergraph, 44.
prematu~ty*ll,
12,21,28,34
4. Firm incisor contact on the leaf gauge continually for 1 to 5 minutes may allow jaw muscle relaxation, sometimes relieving pain and usually permitting the jaw to retrude naturally, assuming a more comfortable position. 10,15,20-22,26,41-43
SUMMARY AND CONCLUSION A new system for recording jaw relations has been described. It is easy to learn to use correctly, is pieasant to the patient while assisting the patient’s neuromusculature into the desired retruded closure at the specific vertical dimension preselected by the dentist, and it uses minimal amounts of recording media. Duplicate records can be quickly made for verification, various recording media may be used, improved stability during mounting is obtained, and the method is applicable in most dentulous and partially edentulous situations. Two elements are used, a dental arch-shaped, partially perforated, thin, waterproof wafer and a disposable paper leaf gauge. The paper leaf gauge is narrower and more solid than the plastic leaf gauge and thus forms a better anterior leg of the tripod with the two condyles on patient-guided terminal hinge closures.9s“3 24 The leaf gauge of preselected thickness is inserted into a slot in the wafer that has been deformed exactly like the occlusal plane by a previous centric occlusion closure. The system
is described in reference
REFERENCES 1. 2.
3. 4. 5. 6. 7. 8.
11,G 15,31,34
3. Patient concentrates biting toward or onto the leaf gauge, not toward the side where the articulating paper or wax is placed or by reflex action away from the
726
is quick, economical, and less complex than most methods presently used. Even so, it accurately reproduced six check-bites on one patient according to comparisons on the Veri-check instrument (Denar Corp., Anaheim, Calif.).*
9. 10. 11. 12. 13. 14. 15.
16.
17. 18. 19. 20.
21.
22.
23.
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NEW DEVICE
FOR RECORDING
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Millstein I?L, Clark RE, Myerson RL: Differential accuracy of silicone-body interocclusal records and associated weight loss due to volatile:. J PROSTHETDENT 33:649, 19'5. 48. Lassila V: Comparison of five interocclusal recording materials. J PROSTHETDENT. 55:215,1986. 49. Woelfel JB, Igarashi T, Winter CM’: Increase in vertical dimension caused by gnathological clutches. ,J Dent Res 50(Special issue): 163, 197 1 (Abstr No. 44 1.
&pm
reque.rtJ to:
DR. JULIAN B. WOELFEL
OHIO STATE UNIVERSITY COLLEGEOF DENTISTRY COLUMBIT. OH 41210
ch to the dif#krmtM
d
Terry T. Tanaka, D.D.S.* University of California, San Diego, Medical Center, San Diego, Calif.
R
heumatologic diseases present major diagnostic and management challenges to the dentist treating temporomandibular joint (TMJ) disorders. Because of their chronicity, variability of symptoms, and tendency to Presented at the Pacific Coast Society of Prosthodontists, Vancouver, B.C., Canada. *Associate Clinical Professor, Department of Surgery, School of Medicine; Director, Facial Pain and TMJ Clinic. THE JOURNAL
OF PROSTHETIC
DENTISTRY
painfully exacerbate and remit, the complexity of these disorders can confuse and frustrate the patient and the dentist. Successful managment requires understanding and differentiation of these disorders early in the diagnostic process. The ability to separate signs and symptoms and assign importance to their relative ciinkal significance is called differential diagnosis. Experience at the Facial Pain Clinic at the University 727