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A technique for the adjustment of castings in a remount procedure
. OPERATIVE
FIXED PROSTHODONTICS SECTION
GORDON SAMUEL
DENTISTRY
EDITORS
H. WILLIAM
J. CHRISTENSEN E. GUYER
WILLIAM
GILMORE
LEFKOWITZ
WILLIAM
F. I’. MALONE
A technique for the adjustment of castings in a remount procedure I’. M. Walker, D.D.S., University
of Southern
M.S.Ed.*
California,
School of Dentistry,
Los Angeles,
lh e o b’jective of this procedure is to correct casting errors of restorations made on an articulator by fitting them in the mouth and then transferring them back to the articulator for final adjustments. The advantages of the procedure are that ridge and groove direction, occlusal anatomy, and the selected vertical dimension of occlusion are all maintained without disturbing the functional (stamp) cusps. This technique is based on the assumption that centric relation is the beginning of any lateral interference. Therefore, correction of eccentric jaw relations and interferences are performed first, and centric jaw relation corrections are made last. The ease with which this may be accomplished is surprising and gratifying.
TECHNIQUE For this technique only type III (preferably hardened) gold alloy should be used for the cast restorations. When cast restorations are first mounted on the articulator, it is not uncommon to find gross interferences that create a large opening in the region of the anterior teeth (Fig. 1). This should not be too disturbing since 1 mm closure at the second molars will be approximately 2.5 mm closure at the central incisors. After the incisal pin is set at the desired vertical dimension, the posterior castings are grossly adjusted with burs and finishing stones until the pin is approximately 1.5 mm from the incisal guide table. Mandibular and maxillary casts are removed from the articulator. The final occlusal anatomy of the castings is now shaped, detailed, and refined with i/4 round, % round, and inverted cone burs. All surfaces of the occlusal anatomy, including the grooves, are *Assistant Professor and Chairman,
0022-3913/81/090263
+ 08$00.80/00
Fixed Prosthodontics.
1981 The C. V. Mosby Co.
Calif.
polished to a low luster finish with small rubber Burlew* s&i disks. The casts are placed back on the articulator, final adjustments are refined using Burlew sulci disks only, and the castings are polished to a high luster with Dixont wire brush wheels. An abrasive polishing compound should not be used. Upon replacing the casts on the articulator, it is usually found that very little opening of the vertical dimension of occlusion remains. When the adjustment of the casting is completed, the incisal pin and the posterior teeth should hold mylar strips 0.0005 inch thick. When completed, the six anterior teeth should offer only slight resistance to the Mylar strip being pulled through. The following rules should be followed for all adjustments.
CORRECT PROTRUSIVE MOVEMENT Protrusive adjustment procedures 1. Place marking ribbon over all castings on the mandibular casts. Move the anterior teeth to an edge-to-edge position on the articulator and slide back to centric occlusion (CO), not centric relation (CR). With different colored marking ribbon, articulate the CR to CO centric slide positions on the teeth by sliding from CR to CO. 2. Whenever possible, protrusive interferences should be removed by recarving and reshaping tooth structure from the buccal cusps of the maxillary and lingual cusps of the mandibular posterior teeth. This is called the BULL rule. 3. Remove all indicated interferences by grinding the distal inclines of the maxillary and the mesial inclines of the mandibular posterior teeth. Do not grind the CR or CO position markings; these will be adjusted later. *J. F. Jelenko and Co., New Rochelle, NY. ?Buffalo Dental, Brooklyn, NY.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
263
WALKER
Fig. 1. Excessiveopening of anterior teeth due to prematurities of posterior teeth before adjustment.
Fig. 2. Direction and location that grooves must be placed to allow for portrusive movement on a tilted lower molar.
Fig. 3. Heavy shaded area on mesial cusp slope of mandibular first premolar is desired contact area against disto-lingual cusp slope of maxillary canine in protrusive movement.
NW Fig. 4. Most mesial portion of CO and most distal portion of CR when grinding in nonworking (NW) ridge and groove direction on maxillary molar.
Exceptions to the protrusive rule 1. If Class II, division I or Class III types of angle occlusion exist, group posterior function is indicated and must be adjusted accordingly. 2. If a mandibular molar is tilted to the mesial of an opposing molar, a groove must be made in the distal surface for the maxillary lingual cusp to pass through (Fig. 2). 3. Contact: of the distal lingual cusp slopes of the maxillary canines and the mesial cusp slopes of the mandibular first premolars is normal (Fig. 3). Do not remove those contacting surfaces in protrusive movement. 4. If markings appear on the mesial inclines of the maxillary and distal inclines of the mandibular posterior teeth in protrusive movement, do not be
264
concerned. These will be corrected in the other movements. 5. If a protrusive interference exists between the CR and CO positions, remove the interference by grinding in ridge and groove directions leaving the most distal portion of CR and the most mesial portion of CO on the maxillary posterior teeth. Leave the most mesial portion of CR and the most distal portion of CO on the manbidular posterior teeth (Fig. 4). It is important that CR and CO be maintained for the vertical dimension of occlusion and reciprocating stops in final closure. 6. If there is evidence of traumatism and fremitus on the individual anterior teeth in protrusive movement, it may be desirable to do minimal, judicial
SEPTEMBER
1981
VOLUME
46
NUMBER
3
ADJUSTMENT
OF CASTINGS
IN REMOUNT
PROCEDURE
NW Fig. 6. Graphic illustration (overall shaded surfaces) of similarity between CR to CO or lateral excursive interference markings.
Fig. 5. Stippled surfacescan be carefully adjusted to create horizontal overlap (overjet) and freedom of movement for anterior teeth.
removal of tooth structure on the lingual aspect of the maxillary teeth and on the labial aspect of the mandibular anterior teeth (Fig. 5). This creates more concavity or horizontal overlap (overjet), allows more freedom of movement, and brings as many anterior teeth as possible into group function.
CORRECT LATERAL MOVEMENTS Lateral adjustment procedures 1. Lateral working and nonworking, or balancing, adjustments must be made simultaneously. 2. Place marking ribbons over all the mandibular posterior castings, and move the articulator into right and left lateral movements. Be sure that all movements follow the border movements set into the articulator completely. Mark the CR to CO position with a different colored ribbon. It will be noted that the CR to CO mark very nearly duplicates the lateral excursion mark (Fig. 6). 3. All adjustments for lateral movements must be made in the direction of the ridges and grooves. Grooves must be the pathways of the functioning cusps to provide clearance (at least 1.5 mm) for the cusps in lateral movement (Figs. 6 and 7). 4. Adjust the mesial inclines of the maxillary posterior teeth and the distal inclines of the mandib-
THE JOURNAL
OF PROSTHETIC
DENTISTRY
ular posterior teeth. This is the reverse of the protrusive rule (Fig. 8). 5. Apply BULL rule where possible. 6. Nearly all lateral adjustments will be made through the two ends of the CR to CO marks. Again, save the two ends as described in step No. 5 of the protrusive rules (Fig. 9). 7. All lateral movements are made from the CR position. The grooves must be the pathways of the functioning cusps for clearance in function. The buccal grooves (nonworking) on the mandibular posterior teeth will be in a distobuccal direction. The lingual grooves (working) of the mandibular posterior teeth will be in a distolingual direction but more mesial than the nonworking grooves. Buccal grooves (working) of the m,axillary posterior teeth will be in a mesiobuccal direction. The lingual grooves (nonworking) or the maxillary posterior teeth will be in a mesiolingual direction but more mesial than the buccal grooves, (Fig. 10). The dentist will observe that where adjustment is required for lateral excursions it will be necessary to move the grooves on the maxillary posterior teeth more distally and the grooves on the mandibular posterior teeth more mesially. Again, be sure to maintain the mesial and distal ends of the slide marks from CR to CO on the maxillary and mandibular posterior teeth (Fig. 11). All excursive movements must be repeated until only the end marks from CR to CO remain. When only the end marks of CR to CO remain, the occlusal stops in bipodization and tripodization start becoming quite evident (Fig. 12).
265
WALKER
E’ig. 7. Adjustment of interference on distal aspect of inner incline. Note position of stone for ridge and groove direction. CO = Centric occlusion or most intercuspal position; CR’ = Centric relation; and CR” = centric occlusion and centric relation coincide after final occlusal adjustment.
M = Mesial. D = Distal. 0 = Outer, I = Inner
Fig. 8. Inclines most commonly adjusted. PRO7 = Protrusive; A4 = mesial; D = distal; 0 = outer; and I = inner.
Fig. 9. Two ends of slide from CR to CO on maxillary and mandibular teeth.
8. Do not grind functioning (stamp) an interference exists on a cusp tip, opposing incline or deepen the fossa. 9. In a Class II relationship, it may be grind distal inclines of the maxillary
inclines This is rule. 10. If working
cusp tips. If adjust the necessary to and mesial
of the mandibular posterior teeth (Fig. 13). especially true when applying the BULL an interference occurs between the noncusps and the axial surfaces of the opposing
SEPTEMBER
1981
VOLUME
46
NUMBER
3
ADJUSTMENT
OF CASTINGS
IN REMOUNT
PROCEDURE
NW
Fig. 10. Direction
of working (W) and nonworking (NW) grooves on maxillary and mandibular teeth.
Fig. 13. Relationship of cusps in lateral function in Class II relation.
Fig. 11. Remaining centric stops of CR to CO slide (interference) after grinding protrusive and lateral in maxillary right first bicuspid.
Fig. 14. Do not remove strippled area for working interference. Relieve buccal cusp of maxillary premolar following the BULL rule.
Fig. 12. Tripodization and bipodization appear as final centric stops in maxillary right first bicuspid. Refinement is completed in centric relation. teeth, adjust the nonworking cusps, not the axial surfaces (BULL rule) (Fig. 14). 11. When all lateral interferences are removed, and only the CR to CO marks remain, there is normally very little centric slide remaining. Centric relation is now ready to be corrected.
CORRECT CENTRIC POSITIONING Centric adjustment procedures 1. Place marking ribbon on the mandibular posterior teeth and move articulator from CR to CO.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 15. Ideal location and size of the points of contact at completion of procedure in mandibular right first molar. Dots indicate final centric after grinding.
2. Again, wherever possible, the BULL rule applies. 3. Refine centric stops by adjusting the mesial slopes of the outer inclines of the upper posterior teeth and the distal slopes of the inner inclines of the lower posterior teeth (Fig. 8). 4. Centric contacts (CR and CO) are refined to small pin-point dots (Fig. 15). 5. Refine the stops toward the central portion of
267
WALKER
Fig. 16. Areas of contact are moved toward center of this mandibular right first molar as procedure progresses. Remaining centric stops after grinding protrusive and lateral.
Fig. 18. Ideal bipodization tion of buccal and lingual imperative.
and tripodization. Reciprocapoints of contact in CR is
Fig. 17. Condyle will not displace after final adjustment as shown CR’ and CO will now coincide at CR’. the tooth, away from the outer perimeter (Fig. 16). 6. If metal shows through the center of the stop, it is striking tots hard and should be lightly refined with a Burlew disk until a solid ribbon mark is obtained. 7. If a large stop remains, correct by removing from the lingual, buccal, and center portions. Save the mesial and distal ends. 8. When all centric slide has been removed, CO becomes the same as CR, which becomes CR’ (Fig. 17). 9. Until the final refinement of CR, CR and CO portions reta.ined appear more as crescents or large dots (Fig. 16). The crescents or dots are now refined and reduced to minimum points of contacts or dots. If the operator has been judicious in his adjustment, he will have little difficulty in obtaining bipodization and tripodization of the functioning cusps in opposing teeth (Fig. 18). 10. Place a high luster on occlusal surfaces with a Dixon wire brush wheel, again using no abrasives.
ANTERIOR
TEETH
1. When the procedure has been completed, posterior teeth should firmly hold 0.0005 inch mylar (Fig. 19), and the six anterior teeth should allow the mylar to slip through with only slight resistance. 268
Fig. 19. Final occlusion and holding ability is tested with 0.0005 inch mylar strip.
2. All centric stops are carefully removed from the six anterior teeth in normal situations. 3. Excursive movement may require grinding to create lingual concavities on the lingual surfaces of the six maxillary anterior teeth and to give a smooth, comfortable, and optimal disclusion of the posterior teeth. 4. Anterior teeth do not act as stops in CO. 5. Anterior teeth touch (preferably a group function) in all excursive movements. Posterior teeth touch only in CO. Canines are the primary teeth of disclusion. SEPTEMBER
1981
VOLUME
46
NUMBER
3
ADJUSTMENT
OF CASTINGS
IN REMOUNT
PROCEDURE
Fig. 20. Occlusal contacts (centric or excursive) should never occur on posterior teeth in stippled wxs.
6. The more Bennett movement, the greater the amount of concavity required on maxillary anterior teeth. The lingual areas of function on the maxillary anterior teeth are not straight or convex but concave. 7. For proper function, maxillary anterior teeth require horizontal and vertical overlap. They cannot be tightly approximated. DISCUSSION One of the most common interferences found in the posterior region is a balancing interference between the distobuccal cusp of the mandibular second and third molars and the mesiolingual cusp of the opposing maxillary molars. It is for this reason that the mandibular molars are made as five cusp teeth. This creates a distobuccal groove for the mesiolingual cusp of the maxillary molars to pass through in a nonworking movement. Buccal cusps of maxillary posterior teeth and lingual cusps of mandibular posterior teeth are nonfunctioning cusps. Thus they can be adjusted and reshaped without too much concern for function. The maxillary posterior teeth should not have contact at any time within a 2 to 3 mm zone lingual to the buccalocclusal transitional line angles. Similar, the mandibular lingualocclusal zone should not have any contacts (Fig. 20). There is a tendency to make the lingual cusps of the mandibular posterior teeth too high, too close together mesiodistally, and too close to the lingual IHE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 21. Top, the upward and forward deflective movement of condyle, jaw, and teeth with first prematurity occurring at CR. Bottom, CO now occurs at CR with deflection removed. Solid radius line represents original displacement.
surfaces of the opposing maxillary te’eth. The same is true where the buccal cusps of the maxillary molar teeth are too close to the buccal axia.1 surfaces of the opposing mandibular teeth. These cusps must have clearance without contact and must have horizontal overlap. This is just as important as the vertical and horizontal overlap of the anterior teeth. The final occlusal adjustments must be made with a Burlew wheel, and the final luster must be placed with Dixon wire brush wheels. Polishing compounds, even rouge, are too abrasive and will abrade away the stops that have been tediously accomplished. Polishing compounds are acceptablle only for axial surfaces. It has been said that the end result of this technique is a “long centric relation.” If the dentist
WALKER
has been judicious in this procedure and has followed the sequence carefully, this is not the case. It is impossible to have bipodization or tripodization with long CR. The dentist must remember that he is adjusting on an incline. The jaw does not move straight upward as it closes. Rather, it rotates around its axis and moves upward and forward on an arc. This allows leaving the most mesial and distal portions of CR and CO. Because of the upward and forward movement of the jaw, it is surprising to find so little change in the position of the mandibular cusp tips (distally) when CO coincides with CR after final adjustment, it is equally surprising that there is no forward displacement of the condyles (Fig. 21).
The importance of maintaining ridge and groove direction, the desired occlusal anatomic form, vertical dimension of occlusion, and proper function without disturbing the functional cusps has been stressed. Acknowledgment and credit for the original development of the techniques and procedures described in this article are due to Dr. Charles Stuart, Ventura, Calif., and to Dr. Peter K. Thomas, Beverly Hills, Calif.
Reprint requeststo: DR.
P. M. WALKER
5538 E. BOBOLINK LN. FRESNO,
CA 93727
SUMMARY A technique for the adjustment (by grinding) of castings in remount procedures has been presented.
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Effect of self-curing fluid volume
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Patrick H. Garvin, D.D.S., M.S., William F. P. Malone, D.D.S., MS., Ph.D, Patrick D. Toto, D.D.S., M.S., and Boleslaw Mazur, D.D.S., M.S.
A comparative evaluation
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13. Patrick Hoag, D.D.S., M.Ed., and Thomas G. Dwyer, D.D.S., MSc.
Flexure fatigue of ten commonly
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Parameters of open-close-clench !3tuart D. Josell, D.M.D., 270
cycles in children
M.Sc.D., Thomas Gay, Ph.D., and James A. Yaeger, D.D.S., Ph.D. SEPTEMBER
1981
VOLUME
46
NUMBER
3
FIXED PROSTHODONTICS SECTION
GORDON SAMUEL
DENTISTRY
EDITORS
H. WILLIAM
J. CHRISTENSEN E. GUYER
WILLIAM
GILMORE
LEFKOWITZ
WILLIAM
F. I’. MALONE
A technique for the adjustment of castings in a remount procedure I’. M. Walker, D.D.S., University
of Southern
M.S.Ed.*
California,
School of Dentistry,
Los Angeles,
lh e o b’jective of this procedure is to correct casting errors of restorations made on an articulator by fitting them in the mouth and then transferring them back to the articulator for final adjustments. The advantages of the procedure are that ridge and groove direction, occlusal anatomy, and the selected vertical dimension of occlusion are all maintained without disturbing the functional (stamp) cusps. This technique is based on the assumption that centric relation is the beginning of any lateral interference. Therefore, correction of eccentric jaw relations and interferences are performed first, and centric jaw relation corrections are made last. The ease with which this may be accomplished is surprising and gratifying.
TECHNIQUE For this technique only type III (preferably hardened) gold alloy should be used for the cast restorations. When cast restorations are first mounted on the articulator, it is not uncommon to find gross interferences that create a large opening in the region of the anterior teeth (Fig. 1). This should not be too disturbing since 1 mm closure at the second molars will be approximately 2.5 mm closure at the central incisors. After the incisal pin is set at the desired vertical dimension, the posterior castings are grossly adjusted with burs and finishing stones until the pin is approximately 1.5 mm from the incisal guide table. Mandibular and maxillary casts are removed from the articulator. The final occlusal anatomy of the castings is now shaped, detailed, and refined with i/4 round, % round, and inverted cone burs. All surfaces of the occlusal anatomy, including the grooves, are *Assistant Professor and Chairman,
0022-3913/81/090263
+ 08$00.80/00
Fixed Prosthodontics.
1981 The C. V. Mosby Co.
Calif.
polished to a low luster finish with small rubber Burlew* s&i disks. The casts are placed back on the articulator, final adjustments are refined using Burlew sulci disks only, and the castings are polished to a high luster with Dixont wire brush wheels. An abrasive polishing compound should not be used. Upon replacing the casts on the articulator, it is usually found that very little opening of the vertical dimension of occlusion remains. When the adjustment of the casting is completed, the incisal pin and the posterior teeth should hold mylar strips 0.0005 inch thick. When completed, the six anterior teeth should offer only slight resistance to the Mylar strip being pulled through. The following rules should be followed for all adjustments.
CORRECT PROTRUSIVE MOVEMENT Protrusive adjustment procedures 1. Place marking ribbon over all castings on the mandibular casts. Move the anterior teeth to an edge-to-edge position on the articulator and slide back to centric occlusion (CO), not centric relation (CR). With different colored marking ribbon, articulate the CR to CO centric slide positions on the teeth by sliding from CR to CO. 2. Whenever possible, protrusive interferences should be removed by recarving and reshaping tooth structure from the buccal cusps of the maxillary and lingual cusps of the mandibular posterior teeth. This is called the BULL rule. 3. Remove all indicated interferences by grinding the distal inclines of the maxillary and the mesial inclines of the mandibular posterior teeth. Do not grind the CR or CO position markings; these will be adjusted later. *J. F. Jelenko and Co., New Rochelle, NY. ?Buffalo Dental, Brooklyn, NY.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
263
WALKER
Fig. 1. Excessiveopening of anterior teeth due to prematurities of posterior teeth before adjustment.
Fig. 2. Direction and location that grooves must be placed to allow for portrusive movement on a tilted lower molar.
Fig. 3. Heavy shaded area on mesial cusp slope of mandibular first premolar is desired contact area against disto-lingual cusp slope of maxillary canine in protrusive movement.
NW Fig. 4. Most mesial portion of CO and most distal portion of CR when grinding in nonworking (NW) ridge and groove direction on maxillary molar.
Exceptions to the protrusive rule 1. If Class II, division I or Class III types of angle occlusion exist, group posterior function is indicated and must be adjusted accordingly. 2. If a mandibular molar is tilted to the mesial of an opposing molar, a groove must be made in the distal surface for the maxillary lingual cusp to pass through (Fig. 2). 3. Contact: of the distal lingual cusp slopes of the maxillary canines and the mesial cusp slopes of the mandibular first premolars is normal (Fig. 3). Do not remove those contacting surfaces in protrusive movement. 4. If markings appear on the mesial inclines of the maxillary and distal inclines of the mandibular posterior teeth in protrusive movement, do not be
264
concerned. These will be corrected in the other movements. 5. If a protrusive interference exists between the CR and CO positions, remove the interference by grinding in ridge and groove directions leaving the most distal portion of CR and the most mesial portion of CO on the maxillary posterior teeth. Leave the most mesial portion of CR and the most distal portion of CO on the manbidular posterior teeth (Fig. 4). It is important that CR and CO be maintained for the vertical dimension of occlusion and reciprocating stops in final closure. 6. If there is evidence of traumatism and fremitus on the individual anterior teeth in protrusive movement, it may be desirable to do minimal, judicial
SEPTEMBER
1981
VOLUME
46
NUMBER
3
ADJUSTMENT
OF CASTINGS
IN REMOUNT
PROCEDURE
NW Fig. 6. Graphic illustration (overall shaded surfaces) of similarity between CR to CO or lateral excursive interference markings.
Fig. 5. Stippled surfacescan be carefully adjusted to create horizontal overlap (overjet) and freedom of movement for anterior teeth.
removal of tooth structure on the lingual aspect of the maxillary teeth and on the labial aspect of the mandibular anterior teeth (Fig. 5). This creates more concavity or horizontal overlap (overjet), allows more freedom of movement, and brings as many anterior teeth as possible into group function.
CORRECT LATERAL MOVEMENTS Lateral adjustment procedures 1. Lateral working and nonworking, or balancing, adjustments must be made simultaneously. 2. Place marking ribbons over all the mandibular posterior castings, and move the articulator into right and left lateral movements. Be sure that all movements follow the border movements set into the articulator completely. Mark the CR to CO position with a different colored ribbon. It will be noted that the CR to CO mark very nearly duplicates the lateral excursion mark (Fig. 6). 3. All adjustments for lateral movements must be made in the direction of the ridges and grooves. Grooves must be the pathways of the functioning cusps to provide clearance (at least 1.5 mm) for the cusps in lateral movement (Figs. 6 and 7). 4. Adjust the mesial inclines of the maxillary posterior teeth and the distal inclines of the mandib-
THE JOURNAL
OF PROSTHETIC
DENTISTRY
ular posterior teeth. This is the reverse of the protrusive rule (Fig. 8). 5. Apply BULL rule where possible. 6. Nearly all lateral adjustments will be made through the two ends of the CR to CO marks. Again, save the two ends as described in step No. 5 of the protrusive rules (Fig. 9). 7. All lateral movements are made from the CR position. The grooves must be the pathways of the functioning cusps for clearance in function. The buccal grooves (nonworking) on the mandibular posterior teeth will be in a distobuccal direction. The lingual grooves (working) of the mandibular posterior teeth will be in a distolingual direction but more mesial than the nonworking grooves. Buccal grooves (working) of the m,axillary posterior teeth will be in a mesiobuccal direction. The lingual grooves (nonworking) or the maxillary posterior teeth will be in a mesiolingual direction but more mesial than the buccal grooves, (Fig. 10). The dentist will observe that where adjustment is required for lateral excursions it will be necessary to move the grooves on the maxillary posterior teeth more distally and the grooves on the mandibular posterior teeth more mesially. Again, be sure to maintain the mesial and distal ends of the slide marks from CR to CO on the maxillary and mandibular posterior teeth (Fig. 11). All excursive movements must be repeated until only the end marks from CR to CO remain. When only the end marks of CR to CO remain, the occlusal stops in bipodization and tripodization start becoming quite evident (Fig. 12).
265
WALKER
E’ig. 7. Adjustment of interference on distal aspect of inner incline. Note position of stone for ridge and groove direction. CO = Centric occlusion or most intercuspal position; CR’ = Centric relation; and CR” = centric occlusion and centric relation coincide after final occlusal adjustment.
M = Mesial. D = Distal. 0 = Outer, I = Inner
Fig. 8. Inclines most commonly adjusted. PRO7 = Protrusive; A4 = mesial; D = distal; 0 = outer; and I = inner.
Fig. 9. Two ends of slide from CR to CO on maxillary and mandibular teeth.
8. Do not grind functioning (stamp) an interference exists on a cusp tip, opposing incline or deepen the fossa. 9. In a Class II relationship, it may be grind distal inclines of the maxillary
inclines This is rule. 10. If working
cusp tips. If adjust the necessary to and mesial
of the mandibular posterior teeth (Fig. 13). especially true when applying the BULL an interference occurs between the noncusps and the axial surfaces of the opposing
SEPTEMBER
1981
VOLUME
46
NUMBER
3
ADJUSTMENT
OF CASTINGS
IN REMOUNT
PROCEDURE
NW
Fig. 10. Direction
of working (W) and nonworking (NW) grooves on maxillary and mandibular teeth.
Fig. 13. Relationship of cusps in lateral function in Class II relation.
Fig. 11. Remaining centric stops of CR to CO slide (interference) after grinding protrusive and lateral in maxillary right first bicuspid.
Fig. 14. Do not remove strippled area for working interference. Relieve buccal cusp of maxillary premolar following the BULL rule.
Fig. 12. Tripodization and bipodization appear as final centric stops in maxillary right first bicuspid. Refinement is completed in centric relation. teeth, adjust the nonworking cusps, not the axial surfaces (BULL rule) (Fig. 14). 11. When all lateral interferences are removed, and only the CR to CO marks remain, there is normally very little centric slide remaining. Centric relation is now ready to be corrected.
CORRECT CENTRIC POSITIONING Centric adjustment procedures 1. Place marking ribbon on the mandibular posterior teeth and move articulator from CR to CO.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 15. Ideal location and size of the points of contact at completion of procedure in mandibular right first molar. Dots indicate final centric after grinding.
2. Again, wherever possible, the BULL rule applies. 3. Refine centric stops by adjusting the mesial slopes of the outer inclines of the upper posterior teeth and the distal slopes of the inner inclines of the lower posterior teeth (Fig. 8). 4. Centric contacts (CR and CO) are refined to small pin-point dots (Fig. 15). 5. Refine the stops toward the central portion of
267
WALKER
Fig. 16. Areas of contact are moved toward center of this mandibular right first molar as procedure progresses. Remaining centric stops after grinding protrusive and lateral.
Fig. 18. Ideal bipodization tion of buccal and lingual imperative.
and tripodization. Reciprocapoints of contact in CR is
Fig. 17. Condyle will not displace after final adjustment as shown CR’ and CO will now coincide at CR’. the tooth, away from the outer perimeter (Fig. 16). 6. If metal shows through the center of the stop, it is striking tots hard and should be lightly refined with a Burlew disk until a solid ribbon mark is obtained. 7. If a large stop remains, correct by removing from the lingual, buccal, and center portions. Save the mesial and distal ends. 8. When all centric slide has been removed, CO becomes the same as CR, which becomes CR’ (Fig. 17). 9. Until the final refinement of CR, CR and CO portions reta.ined appear more as crescents or large dots (Fig. 16). The crescents or dots are now refined and reduced to minimum points of contacts or dots. If the operator has been judicious in his adjustment, he will have little difficulty in obtaining bipodization and tripodization of the functioning cusps in opposing teeth (Fig. 18). 10. Place a high luster on occlusal surfaces with a Dixon wire brush wheel, again using no abrasives.
ANTERIOR
TEETH
1. When the procedure has been completed, posterior teeth should firmly hold 0.0005 inch mylar (Fig. 19), and the six anterior teeth should allow the mylar to slip through with only slight resistance. 268
Fig. 19. Final occlusion and holding ability is tested with 0.0005 inch mylar strip.
2. All centric stops are carefully removed from the six anterior teeth in normal situations. 3. Excursive movement may require grinding to create lingual concavities on the lingual surfaces of the six maxillary anterior teeth and to give a smooth, comfortable, and optimal disclusion of the posterior teeth. 4. Anterior teeth do not act as stops in CO. 5. Anterior teeth touch (preferably a group function) in all excursive movements. Posterior teeth touch only in CO. Canines are the primary teeth of disclusion. SEPTEMBER
1981
VOLUME
46
NUMBER
3
ADJUSTMENT
OF CASTINGS
IN REMOUNT
PROCEDURE
Fig. 20. Occlusal contacts (centric or excursive) should never occur on posterior teeth in stippled wxs.
6. The more Bennett movement, the greater the amount of concavity required on maxillary anterior teeth. The lingual areas of function on the maxillary anterior teeth are not straight or convex but concave. 7. For proper function, maxillary anterior teeth require horizontal and vertical overlap. They cannot be tightly approximated. DISCUSSION One of the most common interferences found in the posterior region is a balancing interference between the distobuccal cusp of the mandibular second and third molars and the mesiolingual cusp of the opposing maxillary molars. It is for this reason that the mandibular molars are made as five cusp teeth. This creates a distobuccal groove for the mesiolingual cusp of the maxillary molars to pass through in a nonworking movement. Buccal cusps of maxillary posterior teeth and lingual cusps of mandibular posterior teeth are nonfunctioning cusps. Thus they can be adjusted and reshaped without too much concern for function. The maxillary posterior teeth should not have contact at any time within a 2 to 3 mm zone lingual to the buccalocclusal transitional line angles. Similar, the mandibular lingualocclusal zone should not have any contacts (Fig. 20). There is a tendency to make the lingual cusps of the mandibular posterior teeth too high, too close together mesiodistally, and too close to the lingual IHE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 21. Top, the upward and forward deflective movement of condyle, jaw, and teeth with first prematurity occurring at CR. Bottom, CO now occurs at CR with deflection removed. Solid radius line represents original displacement.
surfaces of the opposing maxillary te’eth. The same is true where the buccal cusps of the maxillary molar teeth are too close to the buccal axia.1 surfaces of the opposing mandibular teeth. These cusps must have clearance without contact and must have horizontal overlap. This is just as important as the vertical and horizontal overlap of the anterior teeth. The final occlusal adjustments must be made with a Burlew wheel, and the final luster must be placed with Dixon wire brush wheels. Polishing compounds, even rouge, are too abrasive and will abrade away the stops that have been tediously accomplished. Polishing compounds are acceptablle only for axial surfaces. It has been said that the end result of this technique is a “long centric relation.” If the dentist
WALKER
has been judicious in this procedure and has followed the sequence carefully, this is not the case. It is impossible to have bipodization or tripodization with long CR. The dentist must remember that he is adjusting on an incline. The jaw does not move straight upward as it closes. Rather, it rotates around its axis and moves upward and forward on an arc. This allows leaving the most mesial and distal portions of CR and CO. Because of the upward and forward movement of the jaw, it is surprising to find so little change in the position of the mandibular cusp tips (distally) when CO coincides with CR after final adjustment, it is equally surprising that there is no forward displacement of the condyles (Fig. 21).
The importance of maintaining ridge and groove direction, the desired occlusal anatomic form, vertical dimension of occlusion, and proper function without disturbing the functional cusps has been stressed. Acknowledgment and credit for the original development of the techniques and procedures described in this article are due to Dr. Charles Stuart, Ventura, Calif., and to Dr. Peter K. Thomas, Beverly Hills, Calif.
Reprint requeststo: DR.
P. M. WALKER
5538 E. BOBOLINK LN. FRESNO,
CA 93727
SUMMARY A technique for the adjustment (by grinding) of castings in remount procedures has been presented.
ARTICLES TO APPEAR IN FUTURE ISSUES Cranioplasty
of the difficult
frontal region
David N. Firtell, D.D.S., M.A., and Richard J. Grisius, D.D.S., M.A.
Treatment with esthetic periodontal
prosthesis
I?. G. Gallon, D.C.D., Roberto Garcia, D.D.S., M.S., Raul G. Caffesse, D.D.S., MS., and Gerald T. Charbeneau, D.D.S., M.S.
Effect of self-curing fluid volume
acrylic resin treatment restorations on the crevicular
Patrick H. Garvin, D.D.S., M.S., William F. P. Malone, D.D.S., MS., Ph.D, Patrick D. Toto, D.D.S., M.S., and Boleslaw Mazur, D.D.S., M.S.
A comparative evaluation
of three post and core techniques
13. Patrick Hoag, D.D.S., M.Ed., and Thomas G. Dwyer, D.D.S., MSc.
Flexure fatigue of ten commonly
used denture base resins
Edward P. Johnston, D.D.S., Jack I. Nicholls, Ph.D., and Dale E. Smith, D.D.S., M.S.D.
Parameters of open-close-clench !3tuart D. Josell, D.M.D., 270
cycles in children
M.Sc.D., Thomas Gay, Ph.D., and James A. Yaeger, D.D.S., Ph.D. SEPTEMBER
1981
VOLUME
46
NUMBER
3