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Clinical evaluation of the mandibular staple bone plate
MAXILLOFACIAL
PROSTHETICS
l
DENTAL IMPLANTS
SECTION EDITORS
I. KENNETH
ADISMAN
RONALD
I’. DESJARDINS
Clinical evaluation of the mandibular bone plate Robert E. McKinstry,
staple
D.M.D.,* and Mohamed A. Aramany, D.M.D., M.S.**
University of Pittsburgh, School of Dental Medicine, and Eye and Ear Hospital of Pittsburgh, Pittsburgh, Pa.
T
he mandibular staple bone plate is a prosthesis used in the treatment of the atrophic edentulous mandible and the congenitally, traumatically, or surgically deformed mandible.’ It provides retention to the inferior border of the mandible in the symphysis region with communication to the oral cavity by two transosteal pins, which serve as a stabilizing device for the prosthesis.
IMPLANT
PLACEMENT
A major problem with the mandibular staple bone plate is the proper placement of the implant. The transosteal pins must enter the oral cavity at approximately the crest of the, ridge and through attached gingiva. The transosteal pins must be 2 to 3 mm medial to the mental foramen to prevent nerve injury. It is recommended that a clear acrylic. resin template be constructed in the shape of an occlusion rim. The labial and lingual margins should be extended fully to the labial and lingual borders of the cast so that the template will present a broad and flat occlusal surface. The mental nerves are located by palpation and marked with gentian violet or a felt-tipped marking pencil. The clear acrylic resin template is seated, and a scratch mark is made in the template on each side at the exact location of the mark locating each mental foramen. The template is then placed on the stone cast and the position of the nerves transferred to the stone cast. The staple is selected by use of a marking guide for the position of the transosteal pins. If the marks are 3 mm or more from the mental nerve position, a regular or modified seven-pin staple should be used. If the marks are 2 mm or less from the mental nerves, then a modified seven-pin staple or a five-pin staple should be used. Drill guide holes are then placed in the template to correspond to the location of the transosteal pins. *Resident, Maxillofacial Prosthetics. **Professor, Department of Prosthodontics; Director, Maxillofacial Center.
374
Fig. 1. Improperly placed staple. Transosteal pins labial to crest of ridge.
Fig. 2. Anteroposterior position of maxillary anterior teeth relative to crest of mandibular ridge is marked on template.
The position of the template relative to the drill guide can lead to misplacement. In some patients, the transosteal pins will be located correctly relative to the mental nerves but will enter the oral cavity either labial or lingual to the crest of the ridge and the maxillary dentition (Fig. 1). The labial or lingual inclination of the transosteal pins presents a difficult problem in
SEPTEMBER
1983
VOLUME
50
NUMBER
3
MANDIBULAR
STAPLE
BONE PLATE
Fig. 3. Properl;, placed staple implant. Note transosteal posts coming through attached gingiva. prosthodontic management. One way to prevent improper angulation is to place the patient’s old denture in the mouth either at the time of surgery or when marking the location of the mental foramen. The position of the maxillary anterior teeth relative to the crest of the ridge is then marked on the mandibular template (Fig. 2). In this manner, the angulation of the transosteal pins can be corrected by making sure they are lingual to the position of the maxillary anterior teeth (Fig. 3). It should be noted that when improper angulation of the transosteal pins occurs, there is little room to place the mandibular anterior teeth over the framework. In some patients, improper angulation of the transosteal pins may result from an uneven inferior border of the mandible. If this situation is observed by the surgeon, the inferior border of the mandible can be leveled by surgical burs. A groove or recess may be cut into the bone, enabling proper seating and angulation of the staple implant.
MANAGEMENT OF THE IMPROPERLY PLACED IMPLANT If the staple implant has been improperly placed so that the pins are angled too far labially to allow placement of teeth over the framework, two alternatives become manifest. The first alternative is to remove the staple and place a new one in the proper position. This treatment may not be possible in many patients owing to difficulty in removing the staple, too little remaining bone left for placement of a new staple implant, and the cost of a second surgical procedure. In determining whether too little bone remains for replacement of the implant, remember that 9 mm of bone height are required in the parasymphysis region.’
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 4. Mucogingival graft placed around left transosteal post in management of chronic gingival inflammatory reaction. (Photograph courtesy of Dr. Andrejs Baumhammers.)
Fig. 5. Mucogingival graft around right transosteal post. (Photograph courtesy of Dr. Andrejs Baumhammers.) This determination is best done by measuring from a lateral preoperative cephalometric radiograph. The second alternative is to remove the fasteners and prepare the transosteal pins as in a crown preparation. The posts are reduced occlusogingivally and buccolingually. Care must be exercised in preparing the post in order to prevent its fracture. A hemostat clamped on the gingival tissue of the transosteal pins will aid in reducing the possibility of fracture during preparation. The operator must avoid preparing the post with steel burs. The contact of the two different metals may generate different electrochemical potentials which will make the metal of the posts active and subject to attack by chloride ions in the tissues.3 Any destruction or removal of the oxide layer renders the metal active and thereby subject to attack by the chloride ions. This corrosion can set up an inflammatory tissue response that may be difficult to control.
375
McKINSTRY
GINGIVAL
MANAGEMENT
The labial placement of the transosteal posts into alveolar mucosa may lead to an inflammatory gingival reaction. The tissue may be managed by a mucogingival graft around the posts (Figs. 4 and 5). Minor inflammation around the posts can be controlled with local treatment, steroids to control edema, and antibiotic coverage. A persistent gingival hyperplasia may be controlled by excision followed by mucogingival grafting.
MANAGEMENT OF COMPRESSION LOADING OF THE IMPLANT A final concern is the recognition and prevention of compression loading. The cause of this phenomenon is either misuse or abuse by the patient or overloading of the implant with the prosthesis. The patient should be instructed on the proper placement of the denture. It is possible for some patients to place the denture improperly, unknowingly placing compressive force on the staple until loosening occurs. The application of excessive masticatory force in the first 8 to 12 weeks can also cause loosening because the bone is osteoid during this period. Dense, calcified bone around the implant probably is not formed for 3 to 4 months. One clue to stress loosening is the impingement of the connecting bar on the gingiva. Overloading of the prosthesis can be prevented by proper block out during processing and through the use of a clear acrylic resin ridge portion of the denture base. Pressure-indicating paste will also disclose compressive loading under the denture. The implant can be unloaded by relining the flange and distal extension bases with soft tissue conditioner and
AND
ARAMANY
removing the Ceka attachments (Jelenko Dental Health Products, Armonk, N.Y.). This procedure will lift the denture from the underlying framework. The implant should become firm in 3 to 6 months.
SUMMARY Some of the problems in the use of the mandibular staple bone plate are improper placement of the implant labiolingually, gingival reaction around the pins, and compression loading of the implant. The use of the patient’s denture to determine proper angulation and the preparation of the transosteal posts can eliminate improper placement. Mucogingival grafting can be used to treat the inflammatory gingival reaction around the posts, and compression loading can be controlled by proper recognition during processing, placement, and patient education. Mucogingival grafting as shown in Figs. 4 and 5 was performed by Dr. Andrejs Baumhammers, Professor of Periodontics, University of Pittsburgh, School of Dental Medicine. REFERENCES 1. Small, I. A.: Survey of experiences with the mandibular staple bone plate. J Oral Surg 36~604, 1978. 2. Small, I. A.: Use of the mandibular staple bone plate in the deformed mandible. J Oral Surg 37~26, 1979. 3. Williams, D. F., and Roaf, R.: Implants in Surgery. Philadelphia, 1973, W. B. Saunders Co. Reprint requests LO: DR. MOHAMED A. ARAMANY EYE AND EAR HOSPITAL OF PITTSBURGH 230 LOTHROP ST. PITTSBURGH, PA 15213
Bound volumes available to subscribers Bound volumes of the JOURNALQF PROSTHETIC DENTISTRY are available to subscribers (only) for the 1983 issues from the publisher at a cost of $39.60 ($49.60 international) for Vol. 49 (January-June) and Vol. 50 (July-December). Shipping charges are included. Each bound volume contains a subject and author index, and all advertising is removed.Copiesare shipped within 30 days after publication of the last issue in the volume. The binding is durable buckram with the journal name, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact Mr. Deans Lynch at The C. V. Mosby Co., 11830 Westline Industrial Drive, St. Louis, MO 63146, USA. Subscriptions must be in force to qualify. Bound volumes are not available in place of a regular JOURNAL subscription.
376
SEPTEMBER
1983
VOLUME
50
NUMBER
3
PROSTHETICS
l
DENTAL IMPLANTS
SECTION EDITORS
I. KENNETH
ADISMAN
RONALD
I’. DESJARDINS
Clinical evaluation of the mandibular bone plate Robert E. McKinstry,
staple
D.M.D.,* and Mohamed A. Aramany, D.M.D., M.S.**
University of Pittsburgh, School of Dental Medicine, and Eye and Ear Hospital of Pittsburgh, Pittsburgh, Pa.
T
he mandibular staple bone plate is a prosthesis used in the treatment of the atrophic edentulous mandible and the congenitally, traumatically, or surgically deformed mandible.’ It provides retention to the inferior border of the mandible in the symphysis region with communication to the oral cavity by two transosteal pins, which serve as a stabilizing device for the prosthesis.
IMPLANT
PLACEMENT
A major problem with the mandibular staple bone plate is the proper placement of the implant. The transosteal pins must enter the oral cavity at approximately the crest of the, ridge and through attached gingiva. The transosteal pins must be 2 to 3 mm medial to the mental foramen to prevent nerve injury. It is recommended that a clear acrylic. resin template be constructed in the shape of an occlusion rim. The labial and lingual margins should be extended fully to the labial and lingual borders of the cast so that the template will present a broad and flat occlusal surface. The mental nerves are located by palpation and marked with gentian violet or a felt-tipped marking pencil. The clear acrylic resin template is seated, and a scratch mark is made in the template on each side at the exact location of the mark locating each mental foramen. The template is then placed on the stone cast and the position of the nerves transferred to the stone cast. The staple is selected by use of a marking guide for the position of the transosteal pins. If the marks are 3 mm or more from the mental nerve position, a regular or modified seven-pin staple should be used. If the marks are 2 mm or less from the mental nerves, then a modified seven-pin staple or a five-pin staple should be used. Drill guide holes are then placed in the template to correspond to the location of the transosteal pins. *Resident, Maxillofacial Prosthetics. **Professor, Department of Prosthodontics; Director, Maxillofacial Center.
374
Fig. 1. Improperly placed staple. Transosteal pins labial to crest of ridge.
Fig. 2. Anteroposterior position of maxillary anterior teeth relative to crest of mandibular ridge is marked on template.
The position of the template relative to the drill guide can lead to misplacement. In some patients, the transosteal pins will be located correctly relative to the mental nerves but will enter the oral cavity either labial or lingual to the crest of the ridge and the maxillary dentition (Fig. 1). The labial or lingual inclination of the transosteal pins presents a difficult problem in
SEPTEMBER
1983
VOLUME
50
NUMBER
3
MANDIBULAR
STAPLE
BONE PLATE
Fig. 3. Properl;, placed staple implant. Note transosteal posts coming through attached gingiva. prosthodontic management. One way to prevent improper angulation is to place the patient’s old denture in the mouth either at the time of surgery or when marking the location of the mental foramen. The position of the maxillary anterior teeth relative to the crest of the ridge is then marked on the mandibular template (Fig. 2). In this manner, the angulation of the transosteal pins can be corrected by making sure they are lingual to the position of the maxillary anterior teeth (Fig. 3). It should be noted that when improper angulation of the transosteal pins occurs, there is little room to place the mandibular anterior teeth over the framework. In some patients, improper angulation of the transosteal pins may result from an uneven inferior border of the mandible. If this situation is observed by the surgeon, the inferior border of the mandible can be leveled by surgical burs. A groove or recess may be cut into the bone, enabling proper seating and angulation of the staple implant.
MANAGEMENT OF THE IMPROPERLY PLACED IMPLANT If the staple implant has been improperly placed so that the pins are angled too far labially to allow placement of teeth over the framework, two alternatives become manifest. The first alternative is to remove the staple and place a new one in the proper position. This treatment may not be possible in many patients owing to difficulty in removing the staple, too little remaining bone left for placement of a new staple implant, and the cost of a second surgical procedure. In determining whether too little bone remains for replacement of the implant, remember that 9 mm of bone height are required in the parasymphysis region.’
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 4. Mucogingival graft placed around left transosteal post in management of chronic gingival inflammatory reaction. (Photograph courtesy of Dr. Andrejs Baumhammers.)
Fig. 5. Mucogingival graft around right transosteal post. (Photograph courtesy of Dr. Andrejs Baumhammers.) This determination is best done by measuring from a lateral preoperative cephalometric radiograph. The second alternative is to remove the fasteners and prepare the transosteal pins as in a crown preparation. The posts are reduced occlusogingivally and buccolingually. Care must be exercised in preparing the post in order to prevent its fracture. A hemostat clamped on the gingival tissue of the transosteal pins will aid in reducing the possibility of fracture during preparation. The operator must avoid preparing the post with steel burs. The contact of the two different metals may generate different electrochemical potentials which will make the metal of the posts active and subject to attack by chloride ions in the tissues.3 Any destruction or removal of the oxide layer renders the metal active and thereby subject to attack by the chloride ions. This corrosion can set up an inflammatory tissue response that may be difficult to control.
375
McKINSTRY
GINGIVAL
MANAGEMENT
The labial placement of the transosteal posts into alveolar mucosa may lead to an inflammatory gingival reaction. The tissue may be managed by a mucogingival graft around the posts (Figs. 4 and 5). Minor inflammation around the posts can be controlled with local treatment, steroids to control edema, and antibiotic coverage. A persistent gingival hyperplasia may be controlled by excision followed by mucogingival grafting.
MANAGEMENT OF COMPRESSION LOADING OF THE IMPLANT A final concern is the recognition and prevention of compression loading. The cause of this phenomenon is either misuse or abuse by the patient or overloading of the implant with the prosthesis. The patient should be instructed on the proper placement of the denture. It is possible for some patients to place the denture improperly, unknowingly placing compressive force on the staple until loosening occurs. The application of excessive masticatory force in the first 8 to 12 weeks can also cause loosening because the bone is osteoid during this period. Dense, calcified bone around the implant probably is not formed for 3 to 4 months. One clue to stress loosening is the impingement of the connecting bar on the gingiva. Overloading of the prosthesis can be prevented by proper block out during processing and through the use of a clear acrylic resin ridge portion of the denture base. Pressure-indicating paste will also disclose compressive loading under the denture. The implant can be unloaded by relining the flange and distal extension bases with soft tissue conditioner and
AND
ARAMANY
removing the Ceka attachments (Jelenko Dental Health Products, Armonk, N.Y.). This procedure will lift the denture from the underlying framework. The implant should become firm in 3 to 6 months.
SUMMARY Some of the problems in the use of the mandibular staple bone plate are improper placement of the implant labiolingually, gingival reaction around the pins, and compression loading of the implant. The use of the patient’s denture to determine proper angulation and the preparation of the transosteal posts can eliminate improper placement. Mucogingival grafting can be used to treat the inflammatory gingival reaction around the posts, and compression loading can be controlled by proper recognition during processing, placement, and patient education. Mucogingival grafting as shown in Figs. 4 and 5 was performed by Dr. Andrejs Baumhammers, Professor of Periodontics, University of Pittsburgh, School of Dental Medicine. REFERENCES 1. Small, I. A.: Survey of experiences with the mandibular staple bone plate. J Oral Surg 36~604, 1978. 2. Small, I. A.: Use of the mandibular staple bone plate in the deformed mandible. J Oral Surg 37~26, 1979. 3. Williams, D. F., and Roaf, R.: Implants in Surgery. Philadelphia, 1973, W. B. Saunders Co. Reprint requests LO: DR. MOHAMED A. ARAMANY EYE AND EAR HOSPITAL OF PITTSBURGH 230 LOTHROP ST. PITTSBURGH, PA 15213
Bound volumes available to subscribers Bound volumes of the JOURNALQF PROSTHETIC DENTISTRY are available to subscribers (only) for the 1983 issues from the publisher at a cost of $39.60 ($49.60 international) for Vol. 49 (January-June) and Vol. 50 (July-December). Shipping charges are included. Each bound volume contains a subject and author index, and all advertising is removed.Copiesare shipped within 30 days after publication of the last issue in the volume. The binding is durable buckram with the journal name, volume number, and year stamped in gold on the spine. Payment must accompany all orders. Contact Mr. Deans Lynch at The C. V. Mosby Co., 11830 Westline Industrial Drive, St. Louis, MO 63146, USA. Subscriptions must be in force to qualify. Bound volumes are not available in place of a regular JOURNAL subscription.
376
SEPTEMBER
1983
VOLUME
50
NUMBER
3