Replacement of a fixed partial denture secondary to abutment fracture
Michael S. Block, DMD,
Paulino Castellon, DDS and
Julio Zavala, CDT
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ABSTRACT
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Background. The authors present a case that demonstrates the efficient replacement of a fixed prosthesis after a patient’s abutment tooth fractured and required extraction. The fractured tooth had a local infection, and the maxillary bone was low-density and limited in height.
Case Description. The authors removed the tooth and grafted the site with particulate bone, while concurrently placing two implants in the edentulous region. After four months, they placed one additional implant and secured a fixed provisional prosthesis within one week.
Clinical Implications. The patient wanted to minimize the time that she would have to be without a fixed prosthesis. The authors met her expectations by using an accelerated treatment plan.
Key Words: Bone grafting; dental implants; fixed prosthesis; infection
A common treatment for partial edentulism is a fixed partial denture that spans the gap of missing teeth, using teeth as abutments to stabilize the partial denture. When a patient’s abutment tooth fractures, clinicians often place implant-supported prostheses.
In this article, we describe the treatment of a patient who fractured her anterior abutment tooth and wanted to minimize the time that she was without a fixed prosthesis.
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CASE DESCRIPTION
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We saw a 55-year-old woman who had fractured her maxillary left first premolar, which resulted in her not being able to use a fixed prosthesis spanning to the second molar. Her medical history was unremarkable, and she was not taking any medication. Her general dental condition was healthy; she had no other areas of caries or periodontal disease.
When we conducted an intraoral evaluation, we found that she had a fractured, nonrestorable, abscessed maxillary left first premolar, with loss of labial bone. Her edentulous span involved the second premolar and the first molar in the maxillary left quadrant. We also determined that she might have had low-density bone secondary to her postmenopausal condition.
We took a panoramic radiograph that indicated a bone height of 12 millimeters for implant placement in the second premolar site and 10 mm in the first molar site. The second premolar and first molar sites had excellent ridge width. We made models of the patient’s maxilla and mandible for further treatment planning.
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TREATMENT PLAN
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As the patient’s bone quality was less than ideal and the placement of the implant in the first molar site required elevation of the sinus floor, immediate provisionalization would not be a successful option.
For prosthetic treatment, we planned to replace the patient’s fixed partial denture with three porcelain-fused-to-metal restorations placed on implants. As we developed the treatment plan, we considered the presence of a localized infection and a large labial bone defect around the fractured abutment tooth, as well as the patient’s desire to minimize the amount of time that she would have to be without a fixed prosthesis. We considered two treatment options. Both protocols initially included managing the infection preoperatively with antibiotic therapy.
The first treatment option involved extracting the fractured abutment tooth and grafting the socket site. After waiting four months for the graft to consolidate, we would place the three implants in the edentulous region. As the patient’s bone quality was less than ideal and the placement of the implant in the first molar site required elevation of the sinus floor, we decided that immediate provisionalization would not be a successful option, and the patient would have to spend an additional four months using a removable temporary prosthesis.
The second treatment option involved placing two implants in the edentulous region distal to the fractured abutment at the time of the extraction and grafting the socket. After waiting four months for the graft to consolidate, we would place the third implant and take transfer impressions, allowing for the placement of a fixed provisional prosthesis within one week of the third implant placement.
Originally, the patient wanted to have a fixed provisional prosthesis placed at the time of the tooth extraction. After we explained the risks of infection and mechanical overload of the posterior implants, she accepted the second treatment option.
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TREATMENT
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Tooth extraction and implant placement.
We used a diagnostic setup based on the patient’s maxilla and mandible models to fabricate a vacuum form to use as a surgical guide stent. After the patient received a five-day regimen of topical chlorhexidine treatment and antibiotics, we extracted the fractured tooth and performed immediate particulate grafting of the labial bone defect.1,2 We made an incision within the sulcus of the fractured tooth that was combined with a crestal incision that extended posteriorly. We extended the incision into the sulcus of the canine but made no vertical incisions in the esthetic zone. We used a posterior vertical release incision to allow for access to the edentulous ridge and to allow for tension-free closure after we placed the graft and implants. We performed a full-thickness mucoperiosteal reflection, exposing the fractured tooth and alveolar crest (Figure 1
). We removed the tooth using a gentle technique to preserve the remaining bone. We removed the granulation tissue within the socket.
After we extracted the tooth, we prepared the implant sites. We used a stent to position the implants so we would avoid placing them in the embrasures. To identify the implant sites, we placed a round bur through the stent in predrilled holes to mark the bone in the correct position. We used a 2.3-mm diameter pilot drill to depth on the second premolar site and to 8 mm on the first molar site. We used the drill on the second molar site according to the manufacturer’s instructions. Because of the limited vertical height in the first molar site, we used osteotomes to elevate the floor of the sinus in the molar site. We placed implants that measured 4 mm in diameter and 11.5 mm in length at the alveolar crest level without countersinking them owing to the limited vertical bone height. We placed cover screws into the implants.
With the internal connection sealed by the cover screws we approximated the flap over the extraction site. To close this site primarily, we released the periosteum by using scissors at the base of the flap. We firmly compacted approximately 0.5 cubic centimeters of mineralized human bone from the University of Miami Tissue Bank (particle size, 350 to 500 micrometers) into the site. After the graft was placed, we used a tapered needle to close the incisions with 4-0 chromic sutures (Figure 2). We sent the patient home with a prescription for a seven-day course of antibiotics and liquid diet instructions. We delivered a temporary removable prosthesis to the patient after one week of healing for esthetic purposes.
We used a two-stage technique because we placed the posterior implant with an endosseous sinus elevation using osteotomes, and the maxillary bone had low density with a radiofrequency index of 59. At three months after the first surgical procedure, we took a panoramic radiograph that indicated excellent ridge height at the first premolar site. The ridge was adequate to palpation for implant placement. At four months, we performed the second surgical procedure while the patient was under local anesthesia.
Exposure of two implants and implant placement in first premolar site.
Our goals for the second surgery included exposure and abutment placement on the two previously placed implants in the second premolar and molar sites, implant placement in the first premolar site, abutment connection, abutment-level impression of the implant sites in preparation for laboratory fabrication of a fixed provisional prosthesis and elimination of the removable temporary prosthesis. Immediate provisionalization of single and multiple units can be successful if the clinician can control the occlusal load carefully and if the patient’s bone quality at the implant site is excellent.3,4
Before the second surgery, we ordered nonprepared abutments (abutments that do not need to be prepared before placement), snap-on transfer copings, abutment analogs and plastic comfort caps for the surgeon (M.S.B.) to use at the second surgical visit. Because the tissue thickness was 2 mm, we selected abutments that had 2-mm gingival collar heights with 6-mm abutment heights. Using these abutments let us leave at least 2 mm between the abutment and the opposing occlusion, which allowed for adequate interocclusal space for fabrication of the provisional prosthesis and final prostheses.
After administering local anesthetic to the patient, we used a 3.5-mm diameter tissue punch to expose the previously placed implants. We placed the nonprepared abutments and secured them to the implants with screws. At the proposed first premolar implant site, we used a tissue punch to remove a circular patch of gingiva (Figure 3). We performed the tissue punch in the planned implant site before elevating the tissue, allowing for a smooth transition around the abutment that also was circular. We made sulcular incisions around the anterior tooth to allow for a minimal flap reflection to visualize the bone thickness at the previously grafted site.
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Figure 3. Tissue punch used in the intended implant site after exposure of the two posterior implants with abutment connection.
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We positioned the implant to allow 2.5 mm between the edges of the implant and the tooth. Implant orientation was parallel to the previously placed implants. We placed the implant approximately 3 mm apical to the proposed gingival margins of the final restoration. A radio frequency index of 76 indicated that we achieved excellent implant stability at placement. Because the index was greater than 60, we could perform immediate provisionalization of the implant.5–7
We placed a nonprepared abutment into the implant immediately after it was placed. We snapped transfer copings over the three abutments (Figure 4) and took a closed-tray impression. After we removed the impression, we placed plastic comfort caps over the abutments. We sent the patient home with a prescription for a five-day course of antibiotics and instructions to take nonnarcotic analgesics for five days.
Laboratory procedure.
We sent the impression to the laboratory. The laboratory technician (J.Z.) snapped abutment analogs into the transfer copings and poured the impression in stone. He snapped plastic comfort caps onto the abutment analogs and used them as waxing sleeves to improve the marginal adaptation of the three-unit fixed provisional prosthesis, which he fabricated using acrylic. While we relieved the occlusion to prevent contact on the canine implant, we allowed occlusion on the two integrated implants.
Placement of the fixed provisional prosthesis.
One week after we placed the implant, the patient returned. We removed the sutures and placed the fixed provisional prosthesis. We were able to remove the plastic comfort caps from the abutments easily. We placed the three-unit fixed temporary prosthesis over the abutments and snapped it into place (Figure 5). Next, we adjusted the occlusion to allow for centric contacts only on the posterior two integrated implants without contact on the first premolar. We used a thin layer of temporary cement owing to the tight fit of the plastic comfort caps.
Final prosthesis fabrication.
We allowed the first premolar implant to integrate for four months. Then we removed the provisional prosthesis and inspected the abutments. We noted that part of the platform of the second premolar implant site was exposed supragingivally. We prepared the abutment on this site according to conventional fixed prosthodontic guidelines (Figure 6). We torqued the abutment screws to 20 newton centimeters. We packed retraction cord around the second premolar site, placed snap-on transfer copings over the first premolar and molar sites, and took a routine impression.
An alternate plan would have been to change the abutment on the second premolar site for one with a shorter collar height, place snap-on transfer copings over all remaining abutments, take an impression and pour a new model similar to the impression we took to fabricate the provisional prosthesis.
In the laboratory, the technician placed abutment analogs over the first premolar and first molar sites and poured acrylic resin on the second premolar site to increase the strength of the die. He poured the model in die stone and fabricated three single porcelain-fused-to-metal crowns.
Final prosthesis delivery.
On the day of the final prosthesis delivery, we removed the fixed provisional prosthesis. We cleaned the abutments with pumice. We delivered the final crowns and cemented them to the abutments within 10 days of the final restoration (Figure 7). The patient used the provisional prosthesis until we delivered the final crowns.
Treatment outcome.
The patient now functions without pain and chews a normal textured diet. She is able to clean around the crowns without compromise. A follow-up radiograph indicated satisfactory crestal bone levels (Figure 8).
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DISCUSSION
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This case demonstrates the efficient restoration of the patient’s maxillary left posterior quadrant. As the patient had an infection and extensive bone loss in the first premolar site, we could not place an implant there at the time of tooth extraction. Because we needed to elevate bone within the sinus in the first molar site and because of the low-density bone in the maxilla, we decided not to fabricate an immediate provisional prosthesis with anterior cantilever of a first premolar pontic. We required that there be sufficient bone quality and at least 10 mm of intact bone height to perform immediate provisionalization after implant placement. The bone in the second premolar location was low in density, with a radiofrequency index of 59 after implant placement, indicating marginal bone implant interfacial strength.
Investigators have shown that placing a graft into an infected, vertically fractured tooth site is effective.1 If the fractured tooth is the cause of the infection, removing an infected tooth can eliminate the infection. Investigators have observed that a particulate mineralized allograft, without membrane coverage, results in preservation of the socket’s width and can allow for bone formation when labial bone is lost.1,8 If the site is not grafted, then a secondary graft would be necessary, resulting in increased morbidity and a questionable chance of success. As long as the patient’s adjacent bone appears healthy and does not have radiolucencies or obvious changes from the local infection, the clinician can place the implants into adjacent bone sites. Assessing the health of the overlying gingiva is important. If the gingiva is pink and does not have signs of infection such as erythema or swelling, then the implant site can be covered with healthy tissue, as was the situation with our patient.8 By placing the implants into the adjacent sites, clinicians have more options to provide patients with a fixed rather than removable provisional prosthesis.
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CONCLUSIONS
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The two-step technique we used provided the patient with the result she desired: an accelerated therapy to provide a fixed prosthesis in the wake of a fractured abutment tooth. By performing the tooth removal and grafting procedures concurrently with the placement of implants, we saved the patient four months of wearing a removable temporary prosthesis. The outcome was good, as demonstrated by the patient’s freedom from pain and ability to resume a normal diet.
Clinicians who have patients in need of expeditious implant therapy, even in the face of infection and low bone density, may be able to apply this technique successfully as we did. Placing grafts at extraction sites is an accepted modality for optimizing implant placement after bone has formed in the socket. Implant placement in adjacent sites that have sufficient bone provide exceptional stability for a provisional prosthesis, because the implant will become integrated over the period during which bone forms in the extraction site. We have found that patients respond well to this approach, because it allows them to have a fixed temporary prosthesis with less functional compromise.
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FOOTNOTES
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Dr. Block is a professor, Department of Oral and Maxillofacial Surgery, Louisiana State University Health Sciences Center School of Dentistry, 1100 Florida Ave., New Orleans, La. 70119, e-mail "mblock{at}lsuhsc.edu". Address reprint requests to Dr. Block.
Dr. Castellon is an associate professor, Department of Prosthodontics, Louisiana State University Health Sciences Center School of Dentistry, New Orleans.
Mr. Zavala is a laboratory technician, Department of Prosthodontics, Louisiana State University Health Sciences Center School of Dentistry, New Orleans.
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REFERENCES
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- Block MS, Finger I, Lytle R. Human mineralized bone in extraction sites before implant placement: preliminary results. JADA 2002;133(12): 1631–8.
- Block MS, Degen M. Horizontal ridge augmentation using human mineralized particulate bone: preliminary results. J Oral Maxillofac Surg 2004;62(9 supplement 2):67–72.[Medline]
- Block M, Finger I, Castellon P, Lirettle D. Single tooth immediate provisional restoration of dental implants: technique and early results. J Oral Maxillofac Surg 2004;62(9):1131–8.[Medline]
- Castellon P, Casadaban M, Block M. Techniques to facilitate provisionalization of implant restorations. J Oral Maxillofac Surg 2005;63(9 supplement 2):72–9.[Medline]
- Ostman PO, Hellman M, Wendelhag I, Sennerby L. Resonance frequency analysis measurements of implants at placement surgery. Int J Prosthodont 2006;19(1):77–83.[Medline]
- Zix J, Kessler-Liechti G, Mericske-Stern R. Stability measurements of 1-stage implants in the maxilla by means of resonance frequency analysis: a pilot study. Int J Oral Maxillofac Implants 2005;20(5): 747–52.[Medline]
- Balshi SF, Allen FD, Wolfinger GJ, Balshi TJ. A resonance frequency analysis assessment of maxillary and mandibular immediately loaded implants. Int J Oral Maxillofac Implants 2005;20(4):584–94.[Medline]
- Block MS. Immediate placement of implants at the time of tooth extraction. In: Block MS, ed. Color atlas of dental implant surgery. 2nd ed. St. Louis: Saunders/Elsevier; 2007:189–209.
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ABSTRACT
CASE DESCRIPTION
