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Intraoral repair of fixed partial dentures
Fixed partial dentures
Intraoral Thaxter
repair H. Miller,
University
of
of fixed D.D.S.,
MS.,*
partial
dentures
and
E. Thayer,
Keith
D.D.S.,
MS.**
Iowa, College of Dentistry, Iowa City, Iowa
1. hrough th e use of pin retainers, fixed partial dentures can often be repaired without removing them from the mouth. Fractured joints (Figs. 1 and 2)) fractured porcelain surfaces, and uncemented or carious abutments can be repaired or replaced without destroying the rest of the prosthesis. Parallel drilling devices for pin retainers were originally introduced for use in drilling into root canals in endodontically treated teeth. Later, with their aid, parallel preparations were made in vital teeth. The “Pontostructor”+ was introduced in 1941 and was used to assureparallelism of retentive pins. The Spirko drill for the Pontostructorl provided the impetus to increased use of the parallel pin technique. Other devices have been used for drilling parallel holes2 One consistsof a drilling guide in a round eccentrically located plastic disc which is attached, with modeling compound and a metal frame, to the teeth. Another device consistsof a hinged arm which is connected to a metal support which in turn is attached with modeling compound to the anterior teeth. A third method is the “Ney Parallel Pin Technic.“+ The drive assemblyof the Ney Kit depends on bushings incorporated in a cold-curing acrylic resin splint to guide the direction and depth when drilling the parallel pin holes either in the cast or in the tooth. The exposed length of the drill beyond the bushings determines the depth of the hole that can be drilled. Courtade, Sanell, and Mann6 described the criteria for an ideal paralleling device. They also indicated that certain engineering principles should be considered when preparing pin retainers. Twice as much surface retention is gained with pinholes as is gained with grooves for the same depth and diameter. Becauseof less frictional retention, less force is required to dislodge a tapered or groove-ridge casting than a casting retained by parallel pins. Greater resistanceto occlusal stress is gained by placing the pins in positions similar to the legs of a table, i.e., at the four corners. *AssistantProfessor,Departmentof Denture Prosthesis. **Professorand Head,Departmentof Crown and Bridge. TJ. F. Jelenkoand Co., Inc., New Rochelle,N. Y. $J. M. Ney Company,Bloomfield,Conn. 382
Fig.
1
Fig.
1. The
joint
between
the two central
Fig.
2. The
joint
between
the two premolar
Kg. 3. The porcelain I?ig. 4. A preparation
is completely on the
incisor
removed
lingual
side
pontics
from of the
pontics
has broken.
has broken.
the metal
base.
teeth
a premolar
for
repair.
The following is a detailed description of the technique of intraoral examples of some of the more common failures of fixed partial dentures may be applied. CONSTRUCTION
OF A SPECIAL
IMPRESSION
repair and to which it
TRAY
An impression of the dental arch containing the fractured fixed partial denture is made in an irreversible hydrocolloid and a stone cast is obtained. A tray for making the final impression in an elastic impression material is constructed of coldIcuring acrylic resin on the cast. The tray should extend to the mesiodistal width of at least one tooth on either side of the fracture. (If the abutments are mobile enough 150 that the pressure of making the final impression for the repair of the fracture ,separates the joint, finger pressure exerted toward the fracture on the exposed teeth will maintain contact between the fractured surfaces.) PREPARATION
OF THE AREA
FOR THE PARALLEL
PIN REPAIR
Mounted stones of various shapes and sizes are used to remove the porcelain or gold from the gingival third of the lingual surface of the fractured area (Figs. 3 and 4). The depression created should be about 4 mm. wide, concave occlusogin-
384
Miller
and
Fig. 5. Using (arrow).
an
Fig.
6. A matrix
Fig.
7. The
Thayer
elastic
containing
pinholes
are
impression
material,
the parallel drilled
by hand
bushings in the
an impression
was
made
of the
prepared
area
is constructed. cast on which
the repair
is to be constructed.
givally, and should extend, if possible, to two teeth on either side of the fractured joint to a maximum depth of 1.5 to 2 mm. in the center of the concave area. The bridge should not be weakened further by grinding the depression too deep. The pinholes are not drilled at this time.
THE IMPRESSION An impression is made in the previously constructed tray in an elastic impression material. The impression covers the prepared area, including the fractured joint (Fig. 5). A maxillomandibular jaw relationship record and an opposing cast are made in the usual manner. After the master cast is obtained from the elastic impression, the amount of available space for the parallel pins is determined. If the pins are to be placed in abutment teeth, care must be taken to locate them so they do not penetrate the pulp. If the pins are to be placed in pontics, they are evenly spaced with as many as four pins used in each pontic. A small round bur (e.g. a No. 2 bur) is used to indicate the location of each pinhole. Factors that determine the number of pins to be used, as well as the depth and position of the pins, are the size of the pins, the size of the area prepared for the splint, and the labiolingual or mesiodistal diameter of the pontics or the proximity to the pulp.
Intraoral
repair
of
fixed
Fig. 8. The same matrix is used to drill the holes in the prepared mouth.
partial
dentures
385
region on the teeth in the
FABRICATION OF THE REPAIR On a duplicate model of the master cast the bushings are placed by using a mandrel to position them one at a time at the points indicated for the pinholes. Sticky wax is used to hold the bushings parallel to one another and in line with the path of insertion. All bushings are then rigidly fixed by making a matrix of a 1:hin layer of cold-curing resin. The matrix is extended to include two teeth on I:ither side of the prepared area and over the incisal edge or occlusal surface (Figs. 13 and 7). The matrix should not engage any undercuts. This amount of coverage Igives maximum stability to the matrix when it is placed on broken fixed partial ‘denture in the mouth. After the resin has cured, it is removed from the duplicate cast, the excess is trimmed away, and then is placecl on the master cast to check its accuracy. Using the drills supplied in the Ney Kit, the parallel pinholes are drilled by hand in the master cast. A drill is inserted in one of the bushings and carefully twisted, by hand, to cut the hole to the depth of the hub on the drill. The other holes are drilled in like manner. Stone dust is cleared away from the drill frequently to prevent chipping of the cast. After all the holes have been drilled, the matrix with the bushings attached is removed from the master cast. The stone cast is lubricated. Pins, a little longer than the depth of the holes, are selected and are inserted in the holes. A thin layer of cold-curing acrylic resin is brushed on the cast to join the pins in a common matrix. The resin is kept clear of the margins of the prepared area. Before the resin has completely set, parallelism is tested by lifting the matrix and pin assembly off the cast and reseating it to be sure that it will draw easily. Inlay wax is then used to finish the pattern to the margins of the prepared area. The pattern consisting of the pins held by resin and inlay wax is removed, sprued,
386
Miller
and Thayer
J. Prosth. Dent. April, 1971
Fig. 9. The repair casting is cemented in place. Fig. 10. A lingual repair is cemented in place.
Fig. 11. The porcelain has been fractured from the left central incisor pontic. Fig. 12. Porcelain has been replaced by using an intraoral pin repair.
invested, and cast in a type C gold by the usual method. The casting is cleaned and carefully placed back on the master cast. It is then finished, polished, and prepared for cementation in the mouth. FITTING AND CEMENTATION The matrix containing the parallel bushings is properly placed on the patient’s teeth over the prepared area. Drilling the pinholes is done by using the Ney Parallel Pin Drive Assembly (Fig. 8) in a belt-driven contra-angle handpiece run at slow speed. The holes are drilled, using the bushings as guides, to the depth as controlled by the hub on the drill. The pinholes in the prepared area correspond to the holes drilled in the stone master cast. After completing the pinhole preparations, the cast matrix repair is cemented to place using a zinc phosphate cement (Figs. 9 and 10). ADAPTATION TO OTHER PROBLEMS Replacement of a broken porcelain surface of a porcelain-fused-to-metal restoration can be accomplished without removing the restoration from the mouth (Figs. 11 and 12). A diagnostic cast is obtained and a cold-curing resin tray covering the labial surfaces of the fractured area and two teeth on either side is constructed. The num-
Volume Number
25 4
Intraoral repair of fixed partial dentures 387
Fig.
Fig.
Fig.
ber of parallel pins that can be placed in the restoration for retention depends upon the type of restoration. Because there is no danger of pulp involvement, more pins can be used to repair a pontic than a crown. Preparation of the part to be repaired is accomplished as previously described. IJsing the prepared resin tray, an impression with an elastic impression material is made and a master cast obtained. A resin matrix containing the parallel bushings is constructed on a duplicate of the master cast. This matrix should cover the prepared area, one tooth on either side, and over the incisal edge or occlusal surface but not to engage any undercuts. The matrix is placed on the master cast and the parallel pinholes are drilled. Pins are properly placed and a thin metal casting is made to which porcelain is fused. The pins, casting, and fused porcelain veneer are then cemented on the restoration. Replacing or recementing a crown which is part of a fixed prosthesis can also be accomplished without removing the prosthesis (Figs. 13, 14, and 15). The fixed prosthesis is sectioned on the mesial and distal sides of the loose crown, the adjacent lingual surfaces are reduced, and an impression is made of the abutment and the adjacent area for the construction of a repair. The repair casting is constructed in the previously described manner. The pinholes are drilled in the teeth and the repair is cemented in the usual manner. CONCLUSIONS It is sometimes desirable to repair a broken joint in a fixed prosthesis or to replace one loose crown in a multiple unit splint by using a parallel pin repair rather than to attempt to remove the prosthesis and risk the possibility of destroying the entire restoration or damaging abutment teeth.
14
15
388
Miller
and Thayer
J. Prosth. Dent. April,1971
References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
13. 14. 15.
Karlstrijm, S.: The Pontostructor Method for the Construction of Fixed Bridges, Crowns, and Inlays, Stockholm, 1955, A. B. Nordiska Bokhandeln. Prothero, J. H.: Prosthetic Dentistry, ed. 4, Chicago, 1928, Medico-Dental Publishing Company, pp. 980-98 1. Hinman, T. D.: Gold Inlays and Hoods, Pacif. Dent. Gaz. 16: 81-91, 1908. Shooshan, E. D.: A Pin-ledge Casting Technic-Its Application in Periodontal Splinting, D. Clin. N. Amer., pp. 189-206, 1960. Baum, L.: New Cast Gold Restorations for Anterior Teeth, J. Amer. Dent. Ass. 61: l-8, 1960. Courtade, G. L., Sanell, C., and Mann, A. W.: The Use of Pins in Restorative Dentistry. Part II, J. PROSTH. DENT. 15: 691-703, 1965. Markham, S.: Plaster Impression for Crown and Bridge, Dent. Dig. 70: 500-503, 1964. Arnold, M. L.: A Method to Incorporate a Fixed Horizontal Pin Splint with a Veneer Crown as a Single Splint, Dent. Dig. 71: 350-353, 1965. Sanell, C., Mann, A. W., and Courtade, G. L.: The Use of Pins in Restorative Dentistry. Part III. The Use of Paralleling Instruments, J. PROSTH. DENT. 16: 286-296, 1966. Courtade, G. L.: Pin Pointers. I. New Instruments, J. PROSTH. DENT. 16: 748-750, 1966. Courtade, G. L.: Pin Pointers. II. Venting and Cross Pinning, J. PROSTH. DENT. 16: 978-980, 1966. Mann, A. W., Courtade, G. L., and Sane& C.: The Use of Pins in Restorative Dentistry. Part I. Parallel Pin Retention Without Using Paralleling Devices, J. PROSTH. DENT. 15: 502-516, 1965. Moffa, J. P., and Phillips, R.: Retentive Properties of Parallel Pin Restorations, J. PROSTH.DENT. 17: 387-400,1967. MSllersten, L.: An Impression Technique for Teeth Prepared for ParaBel Pins, J. PROSTH. DENT. 18: 579-582, 1967. Johnston, J. F.: The Application and Construction of the Pin-ledge Retainer, J. PROSTH. DENT. 4: 559-567, 1953.
DRS. MILLER AND THAYER: COLLEGE OF DENTISTRY THE
UNIVERSITY
IOWA
CITY,IOWA
OF IOWA
52240
Intraoral Thaxter
repair H. Miller,
University
of
of fixed D.D.S.,
MS.,*
partial
dentures
and
E. Thayer,
Keith
D.D.S.,
MS.**
Iowa, College of Dentistry, Iowa City, Iowa
1. hrough th e use of pin retainers, fixed partial dentures can often be repaired without removing them from the mouth. Fractured joints (Figs. 1 and 2)) fractured porcelain surfaces, and uncemented or carious abutments can be repaired or replaced without destroying the rest of the prosthesis. Parallel drilling devices for pin retainers were originally introduced for use in drilling into root canals in endodontically treated teeth. Later, with their aid, parallel preparations were made in vital teeth. The “Pontostructor”+ was introduced in 1941 and was used to assureparallelism of retentive pins. The Spirko drill for the Pontostructorl provided the impetus to increased use of the parallel pin technique. Other devices have been used for drilling parallel holes2 One consistsof a drilling guide in a round eccentrically located plastic disc which is attached, with modeling compound and a metal frame, to the teeth. Another device consistsof a hinged arm which is connected to a metal support which in turn is attached with modeling compound to the anterior teeth. A third method is the “Ney Parallel Pin Technic.“+ The drive assemblyof the Ney Kit depends on bushings incorporated in a cold-curing acrylic resin splint to guide the direction and depth when drilling the parallel pin holes either in the cast or in the tooth. The exposed length of the drill beyond the bushings determines the depth of the hole that can be drilled. Courtade, Sanell, and Mann6 described the criteria for an ideal paralleling device. They also indicated that certain engineering principles should be considered when preparing pin retainers. Twice as much surface retention is gained with pinholes as is gained with grooves for the same depth and diameter. Becauseof less frictional retention, less force is required to dislodge a tapered or groove-ridge casting than a casting retained by parallel pins. Greater resistanceto occlusal stress is gained by placing the pins in positions similar to the legs of a table, i.e., at the four corners. *AssistantProfessor,Departmentof Denture Prosthesis. **Professorand Head,Departmentof Crown and Bridge. TJ. F. Jelenkoand Co., Inc., New Rochelle,N. Y. $J. M. Ney Company,Bloomfield,Conn. 382
Fig.
1
Fig.
1. The
joint
between
the two central
Fig.
2. The
joint
between
the two premolar
Kg. 3. The porcelain I?ig. 4. A preparation
is completely on the
incisor
removed
lingual
side
pontics
from of the
pontics
has broken.
has broken.
the metal
base.
teeth
a premolar
for
repair.
The following is a detailed description of the technique of intraoral examples of some of the more common failures of fixed partial dentures may be applied. CONSTRUCTION
OF A SPECIAL
IMPRESSION
repair and to which it
TRAY
An impression of the dental arch containing the fractured fixed partial denture is made in an irreversible hydrocolloid and a stone cast is obtained. A tray for making the final impression in an elastic impression material is constructed of coldIcuring acrylic resin on the cast. The tray should extend to the mesiodistal width of at least one tooth on either side of the fracture. (If the abutments are mobile enough 150 that the pressure of making the final impression for the repair of the fracture ,separates the joint, finger pressure exerted toward the fracture on the exposed teeth will maintain contact between the fractured surfaces.) PREPARATION
OF THE AREA
FOR THE PARALLEL
PIN REPAIR
Mounted stones of various shapes and sizes are used to remove the porcelain or gold from the gingival third of the lingual surface of the fractured area (Figs. 3 and 4). The depression created should be about 4 mm. wide, concave occlusogin-
384
Miller
and
Fig. 5. Using (arrow).
an
Fig.
6. A matrix
Fig.
7. The
Thayer
elastic
containing
pinholes
are
impression
material,
the parallel drilled
by hand
bushings in the
an impression
was
made
of the
prepared
area
is constructed. cast on which
the repair
is to be constructed.
givally, and should extend, if possible, to two teeth on either side of the fractured joint to a maximum depth of 1.5 to 2 mm. in the center of the concave area. The bridge should not be weakened further by grinding the depression too deep. The pinholes are not drilled at this time.
THE IMPRESSION An impression is made in the previously constructed tray in an elastic impression material. The impression covers the prepared area, including the fractured joint (Fig. 5). A maxillomandibular jaw relationship record and an opposing cast are made in the usual manner. After the master cast is obtained from the elastic impression, the amount of available space for the parallel pins is determined. If the pins are to be placed in abutment teeth, care must be taken to locate them so they do not penetrate the pulp. If the pins are to be placed in pontics, they are evenly spaced with as many as four pins used in each pontic. A small round bur (e.g. a No. 2 bur) is used to indicate the location of each pinhole. Factors that determine the number of pins to be used, as well as the depth and position of the pins, are the size of the pins, the size of the area prepared for the splint, and the labiolingual or mesiodistal diameter of the pontics or the proximity to the pulp.
Intraoral
repair
of
fixed
Fig. 8. The same matrix is used to drill the holes in the prepared mouth.
partial
dentures
385
region on the teeth in the
FABRICATION OF THE REPAIR On a duplicate model of the master cast the bushings are placed by using a mandrel to position them one at a time at the points indicated for the pinholes. Sticky wax is used to hold the bushings parallel to one another and in line with the path of insertion. All bushings are then rigidly fixed by making a matrix of a 1:hin layer of cold-curing resin. The matrix is extended to include two teeth on I:ither side of the prepared area and over the incisal edge or occlusal surface (Figs. 13 and 7). The matrix should not engage any undercuts. This amount of coverage Igives maximum stability to the matrix when it is placed on broken fixed partial ‘denture in the mouth. After the resin has cured, it is removed from the duplicate cast, the excess is trimmed away, and then is placecl on the master cast to check its accuracy. Using the drills supplied in the Ney Kit, the parallel pinholes are drilled by hand in the master cast. A drill is inserted in one of the bushings and carefully twisted, by hand, to cut the hole to the depth of the hub on the drill. The other holes are drilled in like manner. Stone dust is cleared away from the drill frequently to prevent chipping of the cast. After all the holes have been drilled, the matrix with the bushings attached is removed from the master cast. The stone cast is lubricated. Pins, a little longer than the depth of the holes, are selected and are inserted in the holes. A thin layer of cold-curing acrylic resin is brushed on the cast to join the pins in a common matrix. The resin is kept clear of the margins of the prepared area. Before the resin has completely set, parallelism is tested by lifting the matrix and pin assembly off the cast and reseating it to be sure that it will draw easily. Inlay wax is then used to finish the pattern to the margins of the prepared area. The pattern consisting of the pins held by resin and inlay wax is removed, sprued,
386
Miller
and Thayer
J. Prosth. Dent. April, 1971
Fig. 9. The repair casting is cemented in place. Fig. 10. A lingual repair is cemented in place.
Fig. 11. The porcelain has been fractured from the left central incisor pontic. Fig. 12. Porcelain has been replaced by using an intraoral pin repair.
invested, and cast in a type C gold by the usual method. The casting is cleaned and carefully placed back on the master cast. It is then finished, polished, and prepared for cementation in the mouth. FITTING AND CEMENTATION The matrix containing the parallel bushings is properly placed on the patient’s teeth over the prepared area. Drilling the pinholes is done by using the Ney Parallel Pin Drive Assembly (Fig. 8) in a belt-driven contra-angle handpiece run at slow speed. The holes are drilled, using the bushings as guides, to the depth as controlled by the hub on the drill. The pinholes in the prepared area correspond to the holes drilled in the stone master cast. After completing the pinhole preparations, the cast matrix repair is cemented to place using a zinc phosphate cement (Figs. 9 and 10). ADAPTATION TO OTHER PROBLEMS Replacement of a broken porcelain surface of a porcelain-fused-to-metal restoration can be accomplished without removing the restoration from the mouth (Figs. 11 and 12). A diagnostic cast is obtained and a cold-curing resin tray covering the labial surfaces of the fractured area and two teeth on either side is constructed. The num-
Volume Number
25 4
Intraoral repair of fixed partial dentures 387
Fig.
Fig.
Fig.
ber of parallel pins that can be placed in the restoration for retention depends upon the type of restoration. Because there is no danger of pulp involvement, more pins can be used to repair a pontic than a crown. Preparation of the part to be repaired is accomplished as previously described. IJsing the prepared resin tray, an impression with an elastic impression material is made and a master cast obtained. A resin matrix containing the parallel bushings is constructed on a duplicate of the master cast. This matrix should cover the prepared area, one tooth on either side, and over the incisal edge or occlusal surface but not to engage any undercuts. The matrix is placed on the master cast and the parallel pinholes are drilled. Pins are properly placed and a thin metal casting is made to which porcelain is fused. The pins, casting, and fused porcelain veneer are then cemented on the restoration. Replacing or recementing a crown which is part of a fixed prosthesis can also be accomplished without removing the prosthesis (Figs. 13, 14, and 15). The fixed prosthesis is sectioned on the mesial and distal sides of the loose crown, the adjacent lingual surfaces are reduced, and an impression is made of the abutment and the adjacent area for the construction of a repair. The repair casting is constructed in the previously described manner. The pinholes are drilled in the teeth and the repair is cemented in the usual manner. CONCLUSIONS It is sometimes desirable to repair a broken joint in a fixed prosthesis or to replace one loose crown in a multiple unit splint by using a parallel pin repair rather than to attempt to remove the prosthesis and risk the possibility of destroying the entire restoration or damaging abutment teeth.
14
15
388
Miller
and Thayer
J. Prosth. Dent. April,1971
References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.
13. 14. 15.
Karlstrijm, S.: The Pontostructor Method for the Construction of Fixed Bridges, Crowns, and Inlays, Stockholm, 1955, A. B. Nordiska Bokhandeln. Prothero, J. H.: Prosthetic Dentistry, ed. 4, Chicago, 1928, Medico-Dental Publishing Company, pp. 980-98 1. Hinman, T. D.: Gold Inlays and Hoods, Pacif. Dent. Gaz. 16: 81-91, 1908. Shooshan, E. D.: A Pin-ledge Casting Technic-Its Application in Periodontal Splinting, D. Clin. N. Amer., pp. 189-206, 1960. Baum, L.: New Cast Gold Restorations for Anterior Teeth, J. Amer. Dent. Ass. 61: l-8, 1960. Courtade, G. L., Sanell, C., and Mann, A. W.: The Use of Pins in Restorative Dentistry. Part II, J. PROSTH. DENT. 15: 691-703, 1965. Markham, S.: Plaster Impression for Crown and Bridge, Dent. Dig. 70: 500-503, 1964. Arnold, M. L.: A Method to Incorporate a Fixed Horizontal Pin Splint with a Veneer Crown as a Single Splint, Dent. Dig. 71: 350-353, 1965. Sanell, C., Mann, A. W., and Courtade, G. L.: The Use of Pins in Restorative Dentistry. Part III. The Use of Paralleling Instruments, J. PROSTH. DENT. 16: 286-296, 1966. Courtade, G. L.: Pin Pointers. I. New Instruments, J. PROSTH. DENT. 16: 748-750, 1966. Courtade, G. L.: Pin Pointers. II. Venting and Cross Pinning, J. PROSTH. DENT. 16: 978-980, 1966. Mann, A. W., Courtade, G. L., and Sane& C.: The Use of Pins in Restorative Dentistry. Part I. Parallel Pin Retention Without Using Paralleling Devices, J. PROSTH. DENT. 15: 502-516, 1965. Moffa, J. P., and Phillips, R.: Retentive Properties of Parallel Pin Restorations, J. PROSTH.DENT. 17: 387-400,1967. MSllersten, L.: An Impression Technique for Teeth Prepared for ParaBel Pins, J. PROSTH. DENT. 18: 579-582, 1967. Johnston, J. F.: The Application and Construction of the Pin-ledge Retainer, J. PROSTH. DENT. 4: 559-567, 1953.
DRS. MILLER AND THAYER: COLLEGE OF DENTISTRY THE
UNIVERSITY
IOWA
CITY,IOWA
OF IOWA
52240