SECTION
EDITOR
esign
ra S. N. White, University
BDentSc,
of Southern
for bone-anchore
MS, MA,a and S. G. Lewis,
California,
School
of Dentistry,
DMD’
Los Angeles,
Fixed implant-supported restorations for edentulous function, but can often be difficult to maintain. Design to enable the patient to maintain optimal oral hygiene enhancing the structural integrity of the prosthesis. 264-S.)
Calif.
patients provide excellent considerations are important while complementing and
(J PROSTHETDENT 1992;67:
ong-term successful use of implants for fixed restorations in edentulous patients was first reported by Branemark et al.’ Centers throughout the world have followed these concepts and achieved successful results.’ However, common prosthodontic-associated complications include inadequate oral hygiene, resulting in gingivitis and gingival hyperplasia, and prosthesis fracture, which must be taken into consideration3 This article shows how these problems can be avoided for most patients with osseointegrated prostheses, provided certain design principles are followed.
flange. Tall gold cylinders 4 mm long are used instead of the 3 mm long cylinders (Fig. 1) to provide more space for cleaning the joint between the abutment cylinder and the gold cylinder. The tall abutment cylinders will also position the junction of the cylinder framework relatively high above the soft tissue, creating more access for cleaning the adjacent surfaces. Because esthetics and phonetics are less affected by the hygiene space in the mandible, larger spaces can be created beneath the mandibular restorations than in maxillary restorations.
METHODS
1. Replace the transfer copings with 4 mm long gold abutment cylinders 2. Make record bases on the master casts of acrylic resm, incorporating the gold cylinders. Do not use a labial flange. 3. Make accurate jaw relation records. When the record bases are in the mouth, it is usually necessary to use one or two gold screws or guide pins to gain stability for each record base. 4. Use the jaw-relation records to mount the casts in a suitable articulator. r 0. Select the artificial teeth to be used. 6. Remove the record bases from the casts. Clean the acrylic resin of all wax and other recording residual. Replace the record bases and, using the acrylic resin and gold coping portion of the record bases, arrange and wax the teeth for a trial fitting in the mouth (Fig. 2). Do not use a labial flange. Fasten each trial base in the mouth with one or two screws. Verify that the gold copings fit into the abutments accurately and proceed with the try-in. When the necessary adjustments are made to the try-in, remove the trial bases from the mouth.
aster
casts
In making casts for an implant prosthesis, the tuberosities and retromolar pads must be included to use as landmarks for positioning the teeth and in establishing the occlusal plane. 1. Place transfer copings in the mouth and make the impressions in the usual manner. 2. Place the abutment analogs in the transfer coping and pour the impressions in dental stone. 3. Remove the impression and transfer copings from the casts; trim and index the base of the casts. ecord
bases
and trial
dentures
The record bases and trial dentures should be made without anterior flanges, to aid the dentist in evaluating the fit of the gold cylinders into the abutment cylinders and to avoid being misled about the soft tissue support and esthetics of the final prosthesis, which will not have a labial
Presented before the Academy of Denture Prosthetics meeting, Palm Springs, Calif. “Assistant Professor, Department of Restorative Dentistry, Director of Restorative Research. “Assistant Professor, Department of Removable Prosthodontics, University of California, School of Dentistry, Los Angeles, Calif. 10/1/33596
264
Procedures
Matrix
,or index
Cut notches in the facial land of the casts (Fig. 2). 2. Lubricate the stone surface and, with the trial dentures in place on the cast, make and apply matrix material to
1.
the
facial
surface
of the
FEBRUARY
teeth.
Wax
1992
the
trial
VOLUME
67
base
NUMBER
and
2
FRAMEWORK
FOR
&ONE-ANCHORED
FPD
Fig. 1. Tab 4 mm gold cylinder on left; short 3 mm gold cylinder on right. Note difference in length of collars on gold cylinders (arrows).
Fig. 3. Teeth on trial denture stone patty to make index.
Fig. 2. Trial denture, similar to conventional trial denture for complete denture application, but contains gold cylinders and has no labial flange.
Fig. 4. Stone index with denture teeth attached, mounted in articulator. Trial denture base and wax have been removed.
notched portion of the cast. The abutments should be blocked out, with wax before the material is applied. The matrix may be made of plaster or a layer of silicone elastomeric material covered with plaster. 3. Remove the matrix and trial dentures from the casts. 4. Remove the teeth from the trial bases and clean the teeth thoroughly. 5. Recover the gold cylinders from the acrylic resin of the trial bases and discard the remainder of the trial bases.
2. Immediately seat the occlusal third of the teeth on each trial denture in a boxed mix of stone (Fig. 3). 3. When the stone matrices have set, remove the boxing wax and index the base of each of the matrices. 4. Seat a trial base and matrix on its respective cast. In most instances, it will be necessary to trim the posterior occlusal portion of each matrix to permit the matrices and the trial bases to seat accurately on the cast. 5. Remove the opposing cast from the articulator, use another mounting ring, and mount the occlusal matrix and trial denture in the articulator (Fig. 4). 6. Remove the trial base and remove and thoroughly clean the teeth. Recover the gold copings from the acrylic resin portion of the trial base and discard the base. 7. Place the cleaned teeth in the matrix (Fig. 4). It may be necessary to hold them in place with a spot of sticky wax on each tooth. 8. Repeat steps 5 through 7 for the other denture.
Alternate
method
Some dentists and technicians index instead of a facial matrix. procedure is suggested:
prefer to use an occlusal Therefore, this alternate
1. Make two boxing wax containers mix of dental stone.
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
and fill them with
a
partially
submerged
in
265
WHITE
Fig. 5. Wax framework developed with respect to teeth and to give adequate hygiene access.
Fig. 6. Convex tissue surface of wax framework is narrow, especially in anterior region between cylinders (1). Framework made buikier and higher immediately distal to distal abutment (2). Facial and lingual finish lines (3). Adequate hygiene access is provided around fixtures.
This alternate method allows better visual access. However, either method allows an optimal framework design because of the exact reproduction of the final position of the denture teeth (Fig. 4).
position
and contour
Because the bottom part of the 4 mm gold cylinder is taller than that of the 3 mm gold cylinder (Fig. l), it is easier to keep wax away from the lower 2 mm of the gold cylinders when waxing the framework. Should wax be placed near the base of the cylinders, the metal may flow to the undersurface of the gold cylinders at the time of casting. This unwanted metal is almost impossible to remove and will prevent the gold cylinders from seating on the abutment cylinders. The surface of the framework over the tissue on the crest of the ridge should be as narrow as possible, especially be266
AND
LEWIS
Fig. 7. Framework with high lingual finish line allowing placement of screw access holes in metal, and strength at distal abutment.
tween the gold cylinders (Figs. 5 and 6). This tissue surface facing the ridge should be convex in a facial-lingual dimension and should be concave in a mesiodistal direction. The surface facing the ridge should always be made of highly polished metal, not acrylic resin. The metalacrylic resin finish line should be placed as far coronally on the lingual surface as possible (Figs 6 and 7). Metal surfaces are more easily cleaned and maintained than acrylic resin surfaces. Plaque tends to accumulate at the metal-acrylic resin junction. Therefore, placing the junction as far coronally as possible will make it further away from the soft tissue on the ridge and will facilitate cleaning the restoration. Screw access holes should be placed in metal whenever possible (Fig. 7). It makes them easier to seal and eliminates cracking of acrylic resin around them. The distal cantilevers should follow the contours of the crest of the ridge, leaving a space of approximately 3 mm for hygiene access (Fig. 8). This space prevents impaction of the bolus between the framework and the ridge, promotes patient comfort, and allows the tongue to function properly. Too large a space under the distal extension causes the tongue to function underneath the prostheses instead of against it. When the prosthesis is too far from the ridge, not only will food accumulate under it, but there will be less room for metal, which affects the strength and rigidity of the prosthesis. In addition, less available space for the placement of teeth compromises the gingival contours of the acrylic resin
Framework
dimensional
form
Whereas access for hygiene is promoted by designing the restoration to be small and narrow, it may well compromise the strength of the prosthesis. Certain minimum dimensions and design principles are necessary to obtain adequate strength and stiffness in the prosthesis. The faciolingual width at the abutment cylinders should be apFEBRUARY
1992
VOLUME
67
NUMBER
2
FRAMEWORK
FOR
BONE-ANCHORED
FPD
proximately 5.5 mm for strength and castability. The faciolingual width between cylinders may be narrower when there is sufficient occlusogingival thickness for rigidity (Fig. 5). The height of the framework should be a minimum of 3 mm between cylinders, but preferably higher to maximize stiffness and strength (Figs. 6 and 8). Stiffness is proportional to the cube of the height, but only directly proportional to the width according to the law of beams. Therefore, it is desirable to increase the height of the framework as much as possible. The height of the framework can be increased on the lingual surface without compromising esthetics, and at the same time provide a smooth, more hygienic metal surface (Figs. 8 and 9). Posteriorly, it is possible to increase the height of the framework both facially and lingually to make a trough-like configuration (Fig.
10).
It is important that the height of the framework be increased at the distal aspect of the distal abutment where the cantilever begins, because this is a common place for fractures to occur (Fig. 6). The maximum length of the cantilever should be 20 mm in the mandibular arch and 10 mm in the maxillary arch. The optimum length of the cantilever arm is dependent on the quality of the bone, the opposing occlusion, and the number, length, and relative position of the fixtures.
axing, casting, framework
and finishing
Fig. 8. Wax framework
showing distal cantilever following ridge contour, high lingual finish line, retentive elements, and relationship of wax to ridgelaps of teeth. Wax is kept 2 mm away from joint between gold cylinders and abutment analogs.
the
1. Attach the 4 mm gold cylinders to the abutment analogs in the casts.
2. Wax the framework
according to the instructions under framework position, contour, and dimensional form in the two preceding sections. Keep the wax at least 2 mm away from the lower part of the gold cylinders. 3. Develop a troughlike design with 18-gauge round retention wires positioned as shown in Figs. 8 and 10. In some instances it may be necessary to add additional retentive loops and crystals or beads for more retention. 4. Sprue, cast and finish the frameworks. Be certain to protect the gold cylinders with metal caps or abutment analogs during the finishing process. r 0. Use 50 pm aluminum oxide and sandblast the internal aspects of the framework.
Processing framewor
the acrylic
resin
on the
Although the outside of the framework must be highly polished, the sandblasted inside will provide micromechanical retention. A silane coupling agent may be used on this side to provide additional chemical bonding of the acrylic resin to the framework. 1. Clean the metal castings thoroughly and seat them on their respective casts. 2. Examine the joints between the gold cylinders and the abutments critically to verify that they fit exactly. If they do not fit, corrective procedures must be done at this time. 3. Attach the frameworks to their respective casts and use THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 9. Anterior view of wax framework shows relationship to teeth, high lingual finish line, and lower facial finish line and shows space and contour around abutments.
4.
5. 6. 7. 8. 9.
the matrix or the ocelusal index to position the teeth on their respective frameworks. Examine the ridge-lap portion of the teeth for contact with the framework. When contact occurs, adjust the tooth or teeth. Wax the teeth in position and carve the wax to the desired form and contours (Fig. 11). Place both waxed dentures in the articulator and adjust the occlusion. Remove the waxed dentures from the casts and place caps or abutment analogs over the gold cylinders. Invest, boil out, pack, recover, and finish the acrylic resin in the usual manner, and retouch the polished metal surface (Fig. 12). Remove the caps or abutment analogs from the gold cylinders and replace the completed dentures on the master casts. 267
WHITE
Fig. 10. Complete waxup of framework shows troughlike construction, retention bars, and abutment location. Denture teeth transferred from stone index to wax on metal framework. High lingual finish line and metal screw access boles are shown.
AND
LEWIS
Fig. 12. Right side of denture with processed acrylic resin on finished polished framework.
Fig. 13. Completed mandibular denture in mouth demonstrates excellent fit of coping to abutment and adequate space for keeping abutments and denture base clean. Fig. Il. Completed waxup showing right side of denture. Cantilever follows soft tissue contour, metal is highly polished, and there is adequate space for hygiene access.
10. Adjust the occlusion and the sturdy, aesthetic implant dentures are ready for the patient. The mandibular denture especially will have ample space to permit adequate cleansing of the abutments, surrounding denture base, and soft tissues (Fig. 13).
Implant-supported fixed restorations for the edentulous patient provide exceptional function and comfort, with well-documented long-term success. The most common complication with this restoration is the patient’s inability to maintain oral hygiene. Certain design considerations that enhance hygienic form and provide exceptional structural integrity have been discussed. Factors enhancing hy-
268
gienic form and strength are mutually interdependent, and the value, longevity, and comfort of implant-supported restorations are enhanced considerably when these factors are incorporated in the prostheses. REFERENCES 1. Adell R, Lekholm U, Rockier B, Branemark PI. A X-year study of osseointegrated implants in the treatment of the edentuious jaw. Int J Oral Surg 1981;10:387-416. 2. Albrektsson T. A multicenter report on osseointegrated oral implants. J PROSTHET DENT 1988;60:75-84. 3. Worthington P, Bolender CL, Taylor TD. The Swedish system of osseointegrated implants: problems and complications encountered during a I-year time period. Int J Oral Maxillofac Implants 198777.84. Reprint
requests
to:
DR. SHANE N. WHITE SCHOOL OF DENTISTRY UNIVERSITY OF SOUTHERN CALIFORNIA Los ANGELES, CA 90089-0641
FEBRUARY
8992
VOLUME
67
NUMBER
2
EDITOR
esign
ra S. N. White, University
BDentSc,
of Southern
for bone-anchore
MS, MA,a and S. G. Lewis,
California,
School
of Dentistry,
DMD’
Los Angeles,
Fixed implant-supported restorations for edentulous function, but can often be difficult to maintain. Design to enable the patient to maintain optimal oral hygiene enhancing the structural integrity of the prosthesis. 264-S.)
Calif.
patients provide excellent considerations are important while complementing and
(J PROSTHETDENT 1992;67:
ong-term successful use of implants for fixed restorations in edentulous patients was first reported by Branemark et al.’ Centers throughout the world have followed these concepts and achieved successful results.’ However, common prosthodontic-associated complications include inadequate oral hygiene, resulting in gingivitis and gingival hyperplasia, and prosthesis fracture, which must be taken into consideration3 This article shows how these problems can be avoided for most patients with osseointegrated prostheses, provided certain design principles are followed.
flange. Tall gold cylinders 4 mm long are used instead of the 3 mm long cylinders (Fig. 1) to provide more space for cleaning the joint between the abutment cylinder and the gold cylinder. The tall abutment cylinders will also position the junction of the cylinder framework relatively high above the soft tissue, creating more access for cleaning the adjacent surfaces. Because esthetics and phonetics are less affected by the hygiene space in the mandible, larger spaces can be created beneath the mandibular restorations than in maxillary restorations.
METHODS
1. Replace the transfer copings with 4 mm long gold abutment cylinders 2. Make record bases on the master casts of acrylic resm, incorporating the gold cylinders. Do not use a labial flange. 3. Make accurate jaw relation records. When the record bases are in the mouth, it is usually necessary to use one or two gold screws or guide pins to gain stability for each record base. 4. Use the jaw-relation records to mount the casts in a suitable articulator. r 0. Select the artificial teeth to be used. 6. Remove the record bases from the casts. Clean the acrylic resin of all wax and other recording residual. Replace the record bases and, using the acrylic resin and gold coping portion of the record bases, arrange and wax the teeth for a trial fitting in the mouth (Fig. 2). Do not use a labial flange. Fasten each trial base in the mouth with one or two screws. Verify that the gold copings fit into the abutments accurately and proceed with the try-in. When the necessary adjustments are made to the try-in, remove the trial bases from the mouth.
aster
casts
In making casts for an implant prosthesis, the tuberosities and retromolar pads must be included to use as landmarks for positioning the teeth and in establishing the occlusal plane. 1. Place transfer copings in the mouth and make the impressions in the usual manner. 2. Place the abutment analogs in the transfer coping and pour the impressions in dental stone. 3. Remove the impression and transfer copings from the casts; trim and index the base of the casts. ecord
bases
and trial
dentures
The record bases and trial dentures should be made without anterior flanges, to aid the dentist in evaluating the fit of the gold cylinders into the abutment cylinders and to avoid being misled about the soft tissue support and esthetics of the final prosthesis, which will not have a labial
Presented before the Academy of Denture Prosthetics meeting, Palm Springs, Calif. “Assistant Professor, Department of Restorative Dentistry, Director of Restorative Research. “Assistant Professor, Department of Removable Prosthodontics, University of California, School of Dentistry, Los Angeles, Calif. 10/1/33596
264
Procedures
Matrix
,or index
Cut notches in the facial land of the casts (Fig. 2). 2. Lubricate the stone surface and, with the trial dentures in place on the cast, make and apply matrix material to
1.
the
facial
surface
of the
FEBRUARY
teeth.
Wax
1992
the
trial
VOLUME
67
base
NUMBER
and
2
FRAMEWORK
FOR
&ONE-ANCHORED
FPD
Fig. 1. Tab 4 mm gold cylinder on left; short 3 mm gold cylinder on right. Note difference in length of collars on gold cylinders (arrows).
Fig. 3. Teeth on trial denture stone patty to make index.
Fig. 2. Trial denture, similar to conventional trial denture for complete denture application, but contains gold cylinders and has no labial flange.
Fig. 4. Stone index with denture teeth attached, mounted in articulator. Trial denture base and wax have been removed.
notched portion of the cast. The abutments should be blocked out, with wax before the material is applied. The matrix may be made of plaster or a layer of silicone elastomeric material covered with plaster. 3. Remove the matrix and trial dentures from the casts. 4. Remove the teeth from the trial bases and clean the teeth thoroughly. 5. Recover the gold cylinders from the acrylic resin of the trial bases and discard the remainder of the trial bases.
2. Immediately seat the occlusal third of the teeth on each trial denture in a boxed mix of stone (Fig. 3). 3. When the stone matrices have set, remove the boxing wax and index the base of each of the matrices. 4. Seat a trial base and matrix on its respective cast. In most instances, it will be necessary to trim the posterior occlusal portion of each matrix to permit the matrices and the trial bases to seat accurately on the cast. 5. Remove the opposing cast from the articulator, use another mounting ring, and mount the occlusal matrix and trial denture in the articulator (Fig. 4). 6. Remove the trial base and remove and thoroughly clean the teeth. Recover the gold copings from the acrylic resin portion of the trial base and discard the base. 7. Place the cleaned teeth in the matrix (Fig. 4). It may be necessary to hold them in place with a spot of sticky wax on each tooth. 8. Repeat steps 5 through 7 for the other denture.
Alternate
method
Some dentists and technicians index instead of a facial matrix. procedure is suggested:
prefer to use an occlusal Therefore, this alternate
1. Make two boxing wax containers mix of dental stone.
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
and fill them with
a
partially
submerged
in
265
WHITE
Fig. 5. Wax framework developed with respect to teeth and to give adequate hygiene access.
Fig. 6. Convex tissue surface of wax framework is narrow, especially in anterior region between cylinders (1). Framework made buikier and higher immediately distal to distal abutment (2). Facial and lingual finish lines (3). Adequate hygiene access is provided around fixtures.
This alternate method allows better visual access. However, either method allows an optimal framework design because of the exact reproduction of the final position of the denture teeth (Fig. 4).
position
and contour
Because the bottom part of the 4 mm gold cylinder is taller than that of the 3 mm gold cylinder (Fig. l), it is easier to keep wax away from the lower 2 mm of the gold cylinders when waxing the framework. Should wax be placed near the base of the cylinders, the metal may flow to the undersurface of the gold cylinders at the time of casting. This unwanted metal is almost impossible to remove and will prevent the gold cylinders from seating on the abutment cylinders. The surface of the framework over the tissue on the crest of the ridge should be as narrow as possible, especially be266
AND
LEWIS
Fig. 7. Framework with high lingual finish line allowing placement of screw access holes in metal, and strength at distal abutment.
tween the gold cylinders (Figs. 5 and 6). This tissue surface facing the ridge should be convex in a facial-lingual dimension and should be concave in a mesiodistal direction. The surface facing the ridge should always be made of highly polished metal, not acrylic resin. The metalacrylic resin finish line should be placed as far coronally on the lingual surface as possible (Figs 6 and 7). Metal surfaces are more easily cleaned and maintained than acrylic resin surfaces. Plaque tends to accumulate at the metal-acrylic resin junction. Therefore, placing the junction as far coronally as possible will make it further away from the soft tissue on the ridge and will facilitate cleaning the restoration. Screw access holes should be placed in metal whenever possible (Fig. 7). It makes them easier to seal and eliminates cracking of acrylic resin around them. The distal cantilevers should follow the contours of the crest of the ridge, leaving a space of approximately 3 mm for hygiene access (Fig. 8). This space prevents impaction of the bolus between the framework and the ridge, promotes patient comfort, and allows the tongue to function properly. Too large a space under the distal extension causes the tongue to function underneath the prostheses instead of against it. When the prosthesis is too far from the ridge, not only will food accumulate under it, but there will be less room for metal, which affects the strength and rigidity of the prosthesis. In addition, less available space for the placement of teeth compromises the gingival contours of the acrylic resin
Framework
dimensional
form
Whereas access for hygiene is promoted by designing the restoration to be small and narrow, it may well compromise the strength of the prosthesis. Certain minimum dimensions and design principles are necessary to obtain adequate strength and stiffness in the prosthesis. The faciolingual width at the abutment cylinders should be apFEBRUARY
1992
VOLUME
67
NUMBER
2
FRAMEWORK
FOR
BONE-ANCHORED
FPD
proximately 5.5 mm for strength and castability. The faciolingual width between cylinders may be narrower when there is sufficient occlusogingival thickness for rigidity (Fig. 5). The height of the framework should be a minimum of 3 mm between cylinders, but preferably higher to maximize stiffness and strength (Figs. 6 and 8). Stiffness is proportional to the cube of the height, but only directly proportional to the width according to the law of beams. Therefore, it is desirable to increase the height of the framework as much as possible. The height of the framework can be increased on the lingual surface without compromising esthetics, and at the same time provide a smooth, more hygienic metal surface (Figs. 8 and 9). Posteriorly, it is possible to increase the height of the framework both facially and lingually to make a trough-like configuration (Fig.
10).
It is important that the height of the framework be increased at the distal aspect of the distal abutment where the cantilever begins, because this is a common place for fractures to occur (Fig. 6). The maximum length of the cantilever should be 20 mm in the mandibular arch and 10 mm in the maxillary arch. The optimum length of the cantilever arm is dependent on the quality of the bone, the opposing occlusion, and the number, length, and relative position of the fixtures.
axing, casting, framework
and finishing
Fig. 8. Wax framework
showing distal cantilever following ridge contour, high lingual finish line, retentive elements, and relationship of wax to ridgelaps of teeth. Wax is kept 2 mm away from joint between gold cylinders and abutment analogs.
the
1. Attach the 4 mm gold cylinders to the abutment analogs in the casts.
2. Wax the framework
according to the instructions under framework position, contour, and dimensional form in the two preceding sections. Keep the wax at least 2 mm away from the lower part of the gold cylinders. 3. Develop a troughlike design with 18-gauge round retention wires positioned as shown in Figs. 8 and 10. In some instances it may be necessary to add additional retentive loops and crystals or beads for more retention. 4. Sprue, cast and finish the frameworks. Be certain to protect the gold cylinders with metal caps or abutment analogs during the finishing process. r 0. Use 50 pm aluminum oxide and sandblast the internal aspects of the framework.
Processing framewor
the acrylic
resin
on the
Although the outside of the framework must be highly polished, the sandblasted inside will provide micromechanical retention. A silane coupling agent may be used on this side to provide additional chemical bonding of the acrylic resin to the framework. 1. Clean the metal castings thoroughly and seat them on their respective casts. 2. Examine the joints between the gold cylinders and the abutments critically to verify that they fit exactly. If they do not fit, corrective procedures must be done at this time. 3. Attach the frameworks to their respective casts and use THE
JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 9. Anterior view of wax framework shows relationship to teeth, high lingual finish line, and lower facial finish line and shows space and contour around abutments.
4.
5. 6. 7. 8. 9.
the matrix or the ocelusal index to position the teeth on their respective frameworks. Examine the ridge-lap portion of the teeth for contact with the framework. When contact occurs, adjust the tooth or teeth. Wax the teeth in position and carve the wax to the desired form and contours (Fig. 11). Place both waxed dentures in the articulator and adjust the occlusion. Remove the waxed dentures from the casts and place caps or abutment analogs over the gold cylinders. Invest, boil out, pack, recover, and finish the acrylic resin in the usual manner, and retouch the polished metal surface (Fig. 12). Remove the caps or abutment analogs from the gold cylinders and replace the completed dentures on the master casts. 267
WHITE
Fig. 10. Complete waxup of framework shows troughlike construction, retention bars, and abutment location. Denture teeth transferred from stone index to wax on metal framework. High lingual finish line and metal screw access boles are shown.
AND
LEWIS
Fig. 12. Right side of denture with processed acrylic resin on finished polished framework.
Fig. 13. Completed mandibular denture in mouth demonstrates excellent fit of coping to abutment and adequate space for keeping abutments and denture base clean. Fig. Il. Completed waxup showing right side of denture. Cantilever follows soft tissue contour, metal is highly polished, and there is adequate space for hygiene access.
10. Adjust the occlusion and the sturdy, aesthetic implant dentures are ready for the patient. The mandibular denture especially will have ample space to permit adequate cleansing of the abutments, surrounding denture base, and soft tissues (Fig. 13).
Implant-supported fixed restorations for the edentulous patient provide exceptional function and comfort, with well-documented long-term success. The most common complication with this restoration is the patient’s inability to maintain oral hygiene. Certain design considerations that enhance hygienic form and provide exceptional structural integrity have been discussed. Factors enhancing hy-
268
gienic form and strength are mutually interdependent, and the value, longevity, and comfort of implant-supported restorations are enhanced considerably when these factors are incorporated in the prostheses. REFERENCES 1. Adell R, Lekholm U, Rockier B, Branemark PI. A X-year study of osseointegrated implants in the treatment of the edentuious jaw. Int J Oral Surg 1981;10:387-416. 2. Albrektsson T. A multicenter report on osseointegrated oral implants. J PROSTHET DENT 1988;60:75-84. 3. Worthington P, Bolender CL, Taylor TD. The Swedish system of osseointegrated implants: problems and complications encountered during a I-year time period. Int J Oral Maxillofac Implants 198777.84. Reprint
requests
to:
DR. SHANE N. WHITE SCHOOL OF DENTISTRY UNIVERSITY OF SOUTHERN CALIFORNIA Los ANGELES, CA 90089-0641
FEBRUARY
8992
VOLUME
67
NUMBER
2
