P e u l , S . ; O l i ~ D D ~ a R o g e r G. E t t e L D D S , M S , b a n d
Erwtn M, 8el~ffer, DDS, MSD c University of Minnesota, School of Dentistry, Minneapolis, Minn. he anterior region of ' a fixed prosthesis, rformanee. A b e v e l e d cially without leaving ,d to the adjaeent p, the implant a r e a w a s Lanent fixed ~ r t i a l the continued p r e s e n c e results h a v e b e e n ttients requiring
b-8.)
Bone resorption, trauma, oral surgery, periodontal disease, and developmental anomalies, when associated with tOoth loss,may result in irregulardefects of the alveolus.~ i d u a l ridp deformities can create esthetic, phonetic, and functional difficultiesfor patients. Adequate hygiene m a y also be a problem because of the irregularly shaped alveolus,Prostheticrestorationover deficientridges makes achieving proper pontic/tissue relationships challenging. The chronic inflammation frequently associated with pontics typicallyresults from a poor pontic/ridge relationship that allows for food impaction I and the accumulation of plaque.2 Ideally,pontics should restore masticalory function, be estheticaUy acceptable to the patient, ~Assistant Professor, Division of Fixed Prosthodontics. t'Clinical Assistant Professor, Division of Periodontics. ~Professor, Division of Periodontics. 0/1/25532
Fig. 1. Ridge defect.
minimize the accumulation of plaque and food debris, and allow for adequate oral hygiene. REVIEW
OF THE
LITERATURE
Until the advent of surgical ridge augmentation, pontic design was often compromised with respect to function and esthetics, s Surgical treatment for residual ridge defects was originally developed for edentulous patients and includes (1) vestibuloplasties, (2) autogenous bone grafts, (3) osteotomies, (4) implants, (5) soft tissue grafts, and (6) alloplastic augmentation. None of these approaches, however, have resulted in unqualified success for the edentulous patient. Recent advances in the treatment of periodontal bony defects have advanced the techniques used in the treatment of localized ridge deformities. These techniques include bone grafts, soft tissue grafts, and alloplastic implants. However, final ridge height following soft tissue grafting was unpredictable, and gingivoplasty was often
Fig. 2. Beveled incision.
IMPROVED PONTIC-RIDGE RELATIONSHIPS
Fig. 3. Alveolar defect uncovered.
Fig. 5. Block positioned on ridge.
Fig. 4. Shaping of HA block.
Fig. 6. Placement of additional particles of HA.
required to obtain optimal contour. Additional wounds (donor sites) resulted in prolonged healing, and the grafts tended to shrink postoperatively, despite deliberate overfill at the time of surgery. 4 Alloplastic augmentation using polymers, gelatin sponge, carbon-impregnated Teflon, plaster of paris, and calcium aluminate ceramics has been attempted. However, wound dehiscence, infection, extrusion or mobility of the implants during function, and resorption of the underlying bone have been reported,s Calcium hydroxyapatite, a biocompatible hydrated calcium phosphate, has been used in both block and particulate form for bone augmentation. Initially,there was some hope that particulate hydroxyapatite (HA) would unite with bone, but biopsies of implant sitesrevealed that particles are joined primarily by fibrous connective tissue,s Uncontrolled particlemigration during healing meant that final ridge height was unpredictable. Block forms of alloplasticmaterials such as ceramics also proved unsuccessful because they would not attach to bone, continued to be mobile, and wound dehiscence of the overlying mucosa was common. These blocks were also unsuitable for load-bear-
ing situations, as they would extrude or become mobile when used as onlays under complete dentures. 5 A porous implant material has been developed which, due to its uniform pore and interconnecting channel size, supports the ingrowth of connective tissue and lamellar bone. Replamine form HA (Interpore 200, Interpore International, Irvine, Calif.) is a pure HA replica of the coral genus Porites (coralline). This material has a uniform pore and pore interconnecting channel diameter of 190 to 230 ~m and a pore size that has been shown to permit maximum penetration and development of mature osteons within implants 7,s Histologic evidence of new bone formation throughout the channels and pores of replamine form HA grafts placed in surgically created defects in long bones of rats and dogs has been reported. 9"12Ettel et al.13 reported new bone, cementum, and a new periodontal ligament in sites grafted with replamine form HA and observed bone deposited on the surface of the implant as well as in the porous channels of the HA. Numerous investigators have reported on the consistent healing sequence following the use of replamine form HA implants as onlays or interpositional grafts in clog mandibles. 1417
THE J O U R N A L OF PROSTHETIC DENTISTRY
235
OLIN, ETTEL, AND SCHAFFER
Fig. 7 . Pontic-to-ridge relationship evaluated.
Fig. 9. Radiograph 1 week after the procedure.
Fig. 8. Flap sutured.
When coralline HA is implanted in bone, fibrovascular tissue proliferates throughout the implant within 1 to 2 weeks, woven bone is laid down within 6 to 8 weeks, and mature lamellar bone is deposited within 3 to 6 months. Is While no inflammatory or foreign body reaction to the implants has been observed, recent reports indicate that block form coralline HA is not suitable as an implant under complete dentures. Rooney et al. t9 reported wound dehiscence caused by trauma in 79% of 29 residual ridges augmented with porous block HA. He also reported that even when treated, dehiscence became a chronic problem with many patients. BothRooney et al. t9 and Peterson 2° reported that infection subsequent to wound dehiscence and mucosal ulceration were common and often resulted in the removal of some or all of the block.
PATIENT HISTORY REPORT Pstient 1 A 70-year-old woman had a ridge defect in the region of the maxillary right central and lateral incisors (Fig. I). Treatment planning included a localizedridge augmenta-
tion using porous coralline HA block to obtain an adequate pontic-to-ridge relationship. Anesthesia was infiltrated into the facial and palatal areas. A flap was designed as described by Allen et al) A Kirkland knife was used to place a bevel on the horizontal palatal incision (Fig. 2). Facial vertical incisions were extended apical to the mucogingival junction. A full thickness flapwas elevated and the alveolardefectwas evaluated (Fig. 3). A block of porous H A was placed in sterilesalineand was shaped to approximate the defect with a scalpelblade (Fig. 4).The shaped block of corallineH A was positioned on the ridge (Fig. 5) and additional particlesof H A were placed around the main block. A sterileamalgam carrier and a plastic instrument were used to achieve proper contours (Fig. 6). The flap was repositioned and the temporary fixed partial denture was replaced to permit visualizationof the pontic-to-ridgerelationship(Fig.7).Final modificationsto the graftcan be made at this time as needed. The flap was sutured with 3-0 and 5-0 silksutures (Fig.8). The temporary fixed partialdenture was cemented and a periodontal dressing was applied.Radiographs made at I week following the procedure indicated the continued presence of the H A block (Fig. 9). Clinical and radiographic examination at 3 years re-
IMPROVED P O N T I C - R I D G E R E L A T I O N S H I P S
Fig. 11. Three-year follow-up.
Fig. 10. Radiograph at 3 years.
vealed a healthy ridge and continued maintenance of ridge height (Figs. 10 and 11). Marginal gingivitiswas noted at this appointment and the patient received additional oral hygiene instruction.
Fig. 12. Ridge defect.
Patient 2 A 62-year-old man had a defect in the region of the maxillary left central incisor (Fig. 12). Surgical treatment and postoperative care proceeded as described for patient No. 1 (Fig. 13). Postoperative healing was uneventful and the implant region was healthy at the 21/2-year follow-up examination. Ridge contours had been maintained and palpation confirmed the presence of the block of coralline HA.
DISCUSSION Without a biopsy it is impossible to determine the exact histologic nature of the implant-bone interface. However, histologic studies of coralline HA onlays in animals have shown the implants to be infiltrated with host osseous tissue. There is limited evidence of bone growth into porous HA placed in human periodontal defects. 21 Previously reported problems of unstable ridge height and granules floating into soft tissue were avoided by using block form HA.
THE J O U R N A L OF P R O S T H E T I C D E N T I S T R Y
Fig. 13. Postoperative plac~ement of HA block. The beveled incision on the palate is advantageous because it permits the flap to be displaced coronofacially without leaving a surface of denuded bone or exposed graft material after flap margins are sutured to the adjacent palatal tissues. Extreme care must be taken to avoid overfill
237
OLIN, ETTEL, AND SCHAFFER
two patients an adequate pontie-to-ridge relationship. Appropriate incisions and of the graft. of denuded of [A 'as
not loaded,
REFERENCES L Stein S. Pontic-residual ridge relationship: a research report. J PROSTHET DENT 1966;16:251-85. 2. Carranza FA. ed. Gtickman's clinical periodontology. 6th ed. Philadelphia: WB SauncIers Co. 1984:928-32. 3. Allen EP, Gainza CS, Farthing GG. Newbold DA. Improved technique fo~ localized ridge augmentation: report of 21 cases. J Periodontol 1985;56:195-9. 4. Greensteln G. Jaflin RA, Hflsen KL. Berman CL. Repair of anterior gingival deformity with Durapatite: a case report. J Periodontol
1965;66:~00-3. 5. Frame j~T; I~fad~CL. The versatility of hydroxyapatite blocks in maxillofacial surgery. Br J Oral Maxillofac Surg 1987;25:452-64. 6. Happ JR. M~Kenna SJ. Use of porous hydroxylapatite blocks for augmentation of a~rophic mandibles. J Oral Maxillofac Surg 1988:46:53845. 7. HulbertSF, Young FA, Mathews RS, Klawitter JJ. Talbert CD. Stelling FH. Potential of ceramic materials as permanently implantable skeletal prosthesis. J Biomed Mater Res 1970;4:433-56. 8. Klawitter JJ. Hulbert SF. Application of porous ceramics tot the
10. Chiroff RT, White EW, Weber JN, Roy DM: Tissue ingrowth of replamine form implants. Biomed Mater Res Syrup 1975;6:29-45: ll. Mitchell OG, Singh IJ, Klein I, Roy DM. Histologic evaluation of porous hydroxylapatit.e implants in rat bone [Abstract]. J Dent Res 1976;55:B243. 12. Holmes RE, Mooney V, Bucholz R. Regeneration within canine radius defects treated by coralline implants and iiiax autografts. Trans Orthop Res Soc 198l;6:229.
13. Ettel RG, Schaffer EM, Bandt CL. Grafting in subcrestal periodontal defects in Rhesus monkeys [Abstract]. J Dent Res 1987;66:196. 14. Roser SM, Brady FAi McKel-~ B. Tissue ingrowth of hydroxylapatite replamineform impla.ntsinthe dog [Abstract],J Dent Res 1977;56:B [72. 15. Sayler K, Holmes R, Johns D. Replamine form porous hydroxyapatite as bone substitute in craniofaclal osseous reconstruction [Abstract]. J Dent Res 1977;56;B173. 16. Silvers MJ, Schaffer EM, Lamprecht EG, Bandt CL, Grafting with Interpore 200, hydroxyapatite in CaSO4 and CaOH, and controls [Abstract].J Dent Res 1988;67:352. 17. Holmes RE, Mooney V. Bone regeneration in canine radius defects treated by corallineimplants and iliacgrafts.Trans Soc Biomater 1984; 7:154. 18. Frame JW. Hydroxyapatite as a biomaterial for alveolar ridge augmentation. Int J Oral Maxillofac Surg 1987;16:242-55. 19. Rooney T, Berman S, Indresano AT. Evaluation of porous block hydroxylapatite for augmentation of alveolar ridges. J Oral Maxillofac Surg 1988;46:15-8. 20. Peterson LJ. Complications with porous hydroxylapatite blocks for ridge augmentation (Letter).J 0ral Maxillofac Surg 1987;45i996. 21. Kenney EB, Lekovic V, Sa Ferreira JC, Han T, Dimitrijevi~ B, Carranza FA. Bone formation within porous hydroxylapatite implants in human periodontal defects. J Periodontal 1986;57:76-83. Reprint requests to:
DR. PAUL S. OLIN SCHOOL OF DENTISTRY 9-450 MALCOLM MOOS HEALTH SCIENCES T O W E R UNIVERSITY OF MINNESOTA MINNEAPOLIS, MN 55455
Erwtn M, 8el~ffer, DDS, MSD c University of Minnesota, School of Dentistry, Minneapolis, Minn. he anterior region of ' a fixed prosthesis, rformanee. A b e v e l e d cially without leaving ,d to the adjaeent p, the implant a r e a w a s Lanent fixed ~ r t i a l the continued p r e s e n c e results h a v e b e e n ttients requiring
b-8.)
Bone resorption, trauma, oral surgery, periodontal disease, and developmental anomalies, when associated with tOoth loss,may result in irregulardefects of the alveolus.~ i d u a l ridp deformities can create esthetic, phonetic, and functional difficultiesfor patients. Adequate hygiene m a y also be a problem because of the irregularly shaped alveolus,Prostheticrestorationover deficientridges makes achieving proper pontic/tissue relationships challenging. The chronic inflammation frequently associated with pontics typicallyresults from a poor pontic/ridge relationship that allows for food impaction I and the accumulation of plaque.2 Ideally,pontics should restore masticalory function, be estheticaUy acceptable to the patient, ~Assistant Professor, Division of Fixed Prosthodontics. t'Clinical Assistant Professor, Division of Periodontics. ~Professor, Division of Periodontics. 0/1/25532
Fig. 1. Ridge defect.
minimize the accumulation of plaque and food debris, and allow for adequate oral hygiene. REVIEW
OF THE
LITERATURE
Until the advent of surgical ridge augmentation, pontic design was often compromised with respect to function and esthetics, s Surgical treatment for residual ridge defects was originally developed for edentulous patients and includes (1) vestibuloplasties, (2) autogenous bone grafts, (3) osteotomies, (4) implants, (5) soft tissue grafts, and (6) alloplastic augmentation. None of these approaches, however, have resulted in unqualified success for the edentulous patient. Recent advances in the treatment of periodontal bony defects have advanced the techniques used in the treatment of localized ridge deformities. These techniques include bone grafts, soft tissue grafts, and alloplastic implants. However, final ridge height following soft tissue grafting was unpredictable, and gingivoplasty was often
Fig. 2. Beveled incision.
IMPROVED PONTIC-RIDGE RELATIONSHIPS
Fig. 3. Alveolar defect uncovered.
Fig. 5. Block positioned on ridge.
Fig. 4. Shaping of HA block.
Fig. 6. Placement of additional particles of HA.
required to obtain optimal contour. Additional wounds (donor sites) resulted in prolonged healing, and the grafts tended to shrink postoperatively, despite deliberate overfill at the time of surgery. 4 Alloplastic augmentation using polymers, gelatin sponge, carbon-impregnated Teflon, plaster of paris, and calcium aluminate ceramics has been attempted. However, wound dehiscence, infection, extrusion or mobility of the implants during function, and resorption of the underlying bone have been reported,s Calcium hydroxyapatite, a biocompatible hydrated calcium phosphate, has been used in both block and particulate form for bone augmentation. Initially,there was some hope that particulate hydroxyapatite (HA) would unite with bone, but biopsies of implant sitesrevealed that particles are joined primarily by fibrous connective tissue,s Uncontrolled particlemigration during healing meant that final ridge height was unpredictable. Block forms of alloplasticmaterials such as ceramics also proved unsuccessful because they would not attach to bone, continued to be mobile, and wound dehiscence of the overlying mucosa was common. These blocks were also unsuitable for load-bear-
ing situations, as they would extrude or become mobile when used as onlays under complete dentures. 5 A porous implant material has been developed which, due to its uniform pore and interconnecting channel size, supports the ingrowth of connective tissue and lamellar bone. Replamine form HA (Interpore 200, Interpore International, Irvine, Calif.) is a pure HA replica of the coral genus Porites (coralline). This material has a uniform pore and pore interconnecting channel diameter of 190 to 230 ~m and a pore size that has been shown to permit maximum penetration and development of mature osteons within implants 7,s Histologic evidence of new bone formation throughout the channels and pores of replamine form HA grafts placed in surgically created defects in long bones of rats and dogs has been reported. 9"12Ettel et al.13 reported new bone, cementum, and a new periodontal ligament in sites grafted with replamine form HA and observed bone deposited on the surface of the implant as well as in the porous channels of the HA. Numerous investigators have reported on the consistent healing sequence following the use of replamine form HA implants as onlays or interpositional grafts in clog mandibles. 1417
THE J O U R N A L OF PROSTHETIC DENTISTRY
235
OLIN, ETTEL, AND SCHAFFER
Fig. 7 . Pontic-to-ridge relationship evaluated.
Fig. 9. Radiograph 1 week after the procedure.
Fig. 8. Flap sutured.
When coralline HA is implanted in bone, fibrovascular tissue proliferates throughout the implant within 1 to 2 weeks, woven bone is laid down within 6 to 8 weeks, and mature lamellar bone is deposited within 3 to 6 months. Is While no inflammatory or foreign body reaction to the implants has been observed, recent reports indicate that block form coralline HA is not suitable as an implant under complete dentures. Rooney et al. t9 reported wound dehiscence caused by trauma in 79% of 29 residual ridges augmented with porous block HA. He also reported that even when treated, dehiscence became a chronic problem with many patients. BothRooney et al. t9 and Peterson 2° reported that infection subsequent to wound dehiscence and mucosal ulceration were common and often resulted in the removal of some or all of the block.
PATIENT HISTORY REPORT Pstient 1 A 70-year-old woman had a ridge defect in the region of the maxillary right central and lateral incisors (Fig. I). Treatment planning included a localizedridge augmenta-
tion using porous coralline HA block to obtain an adequate pontic-to-ridge relationship. Anesthesia was infiltrated into the facial and palatal areas. A flap was designed as described by Allen et al) A Kirkland knife was used to place a bevel on the horizontal palatal incision (Fig. 2). Facial vertical incisions were extended apical to the mucogingival junction. A full thickness flapwas elevated and the alveolardefectwas evaluated (Fig. 3). A block of porous H A was placed in sterilesalineand was shaped to approximate the defect with a scalpelblade (Fig. 4).The shaped block of corallineH A was positioned on the ridge (Fig. 5) and additional particlesof H A were placed around the main block. A sterileamalgam carrier and a plastic instrument were used to achieve proper contours (Fig. 6). The flap was repositioned and the temporary fixed partial denture was replaced to permit visualizationof the pontic-to-ridgerelationship(Fig.7).Final modificationsto the graftcan be made at this time as needed. The flap was sutured with 3-0 and 5-0 silksutures (Fig.8). The temporary fixed partialdenture was cemented and a periodontal dressing was applied.Radiographs made at I week following the procedure indicated the continued presence of the H A block (Fig. 9). Clinical and radiographic examination at 3 years re-
IMPROVED P O N T I C - R I D G E R E L A T I O N S H I P S
Fig. 11. Three-year follow-up.
Fig. 10. Radiograph at 3 years.
vealed a healthy ridge and continued maintenance of ridge height (Figs. 10 and 11). Marginal gingivitiswas noted at this appointment and the patient received additional oral hygiene instruction.
Fig. 12. Ridge defect.
Patient 2 A 62-year-old man had a defect in the region of the maxillary left central incisor (Fig. 12). Surgical treatment and postoperative care proceeded as described for patient No. 1 (Fig. 13). Postoperative healing was uneventful and the implant region was healthy at the 21/2-year follow-up examination. Ridge contours had been maintained and palpation confirmed the presence of the block of coralline HA.
DISCUSSION Without a biopsy it is impossible to determine the exact histologic nature of the implant-bone interface. However, histologic studies of coralline HA onlays in animals have shown the implants to be infiltrated with host osseous tissue. There is limited evidence of bone growth into porous HA placed in human periodontal defects. 21 Previously reported problems of unstable ridge height and granules floating into soft tissue were avoided by using block form HA.
THE J O U R N A L OF P R O S T H E T I C D E N T I S T R Y
Fig. 13. Postoperative plac~ement of HA block. The beveled incision on the palate is advantageous because it permits the flap to be displaced coronofacially without leaving a surface of denuded bone or exposed graft material after flap margins are sutured to the adjacent palatal tissues. Extreme care must be taken to avoid overfill
237
OLIN, ETTEL, AND SCHAFFER
two patients an adequate pontie-to-ridge relationship. Appropriate incisions and of the graft. of denuded of [A 'as
not loaded,
REFERENCES L Stein S. Pontic-residual ridge relationship: a research report. J PROSTHET DENT 1966;16:251-85. 2. Carranza FA. ed. Gtickman's clinical periodontology. 6th ed. Philadelphia: WB SauncIers Co. 1984:928-32. 3. Allen EP, Gainza CS, Farthing GG. Newbold DA. Improved technique fo~ localized ridge augmentation: report of 21 cases. J Periodontol 1985;56:195-9. 4. Greensteln G. Jaflin RA, Hflsen KL. Berman CL. Repair of anterior gingival deformity with Durapatite: a case report. J Periodontol
1965;66:~00-3. 5. Frame j~T; I~fad~CL. The versatility of hydroxyapatite blocks in maxillofacial surgery. Br J Oral Maxillofac Surg 1987;25:452-64. 6. Happ JR. M~Kenna SJ. Use of porous hydroxylapatite blocks for augmentation of a~rophic mandibles. J Oral Maxillofac Surg 1988:46:53845. 7. HulbertSF, Young FA, Mathews RS, Klawitter JJ. Talbert CD. Stelling FH. Potential of ceramic materials as permanently implantable skeletal prosthesis. J Biomed Mater Res 1970;4:433-56. 8. Klawitter JJ. Hulbert SF. Application of porous ceramics tot the
10. Chiroff RT, White EW, Weber JN, Roy DM: Tissue ingrowth of replamine form implants. Biomed Mater Res Syrup 1975;6:29-45: ll. Mitchell OG, Singh IJ, Klein I, Roy DM. Histologic evaluation of porous hydroxylapatit.e implants in rat bone [Abstract]. J Dent Res 1976;55:B243. 12. Holmes RE, Mooney V, Bucholz R. Regeneration within canine radius defects treated by coralline implants and iiiax autografts. Trans Orthop Res Soc 198l;6:229.
13. Ettel RG, Schaffer EM, Bandt CL. Grafting in subcrestal periodontal defects in Rhesus monkeys [Abstract]. J Dent Res 1987;66:196. 14. Roser SM, Brady FAi McKel-~ B. Tissue ingrowth of hydroxylapatite replamineform impla.ntsinthe dog [Abstract],J Dent Res 1977;56:B [72. 15. Sayler K, Holmes R, Johns D. Replamine form porous hydroxyapatite as bone substitute in craniofaclal osseous reconstruction [Abstract]. J Dent Res 1977;56;B173. 16. Silvers MJ, Schaffer EM, Lamprecht EG, Bandt CL, Grafting with Interpore 200, hydroxyapatite in CaSO4 and CaOH, and controls [Abstract].J Dent Res 1988;67:352. 17. Holmes RE, Mooney V. Bone regeneration in canine radius defects treated by corallineimplants and iliacgrafts.Trans Soc Biomater 1984; 7:154. 18. Frame JW. Hydroxyapatite as a biomaterial for alveolar ridge augmentation. Int J Oral Maxillofac Surg 1987;16:242-55. 19. Rooney T, Berman S, Indresano AT. Evaluation of porous block hydroxylapatite for augmentation of alveolar ridges. J Oral Maxillofac Surg 1988;46:15-8. 20. Peterson LJ. Complications with porous hydroxylapatite blocks for ridge augmentation (Letter).J 0ral Maxillofac Surg 1987;45i996. 21. Kenney EB, Lekovic V, Sa Ferreira JC, Han T, Dimitrijevi~ B, Carranza FA. Bone formation within porous hydroxylapatite implants in human periodontal defects. J Periodontal 1986;57:76-83. Reprint requests to:
DR. PAUL S. OLIN SCHOOL OF DENTISTRY 9-450 MALCOLM MOOS HEALTH SCIENCES T O W E R UNIVERSITY OF MINNESOTA MINNEAPOLIS, MN 55455
