Dental implants are currently well accepted as a safe and effective means for tooth replacement.1 One common application of implant rehabilitation is the replacement of a single missing tooth. Despite the excellent outcomes typically obtained, many patients are hesitant to accept treatment. One reason for this resistance is the amount of time required to replace a missing tooth with an implant restoration compared to fabricating a three-unit fixed bridge. The commonly accepted treatment protocol includes a waiting period following implant placement of 3 months in the mandible and 6 months in the maxilla prior to exposure and restoration.2 While the period of integration results in highly predictable outcomes, patients object to this prolonged treatment time. Clearly, increased case acceptance can be anticipated for any protocol that includes safe and effective treatment that is completed quickly and does not interfere with the patient’s daily activities.
Preliminary reports in the literature support the feasibility of eliminating the waiting period between single-tooth implant placement and the delivery of the restoration. In describing the results of 14 consecutively placed implants (nine TPS-coated and five HA-coated Steri-Oss implants, Nobel Biocare) that received immediate provisional restoration, Wohrle3 reported all implants to be osseointegrated and in function after 12 months. Good soft tissue height was maintained around the implant crown in most cases, with a loss of soft tissue height greater than 1 mm in only two patients. Similar results have been reported for 12 immediately restored implants followed for a 24-month period.4
Another report of 17 implants (Frialit-2 implants, Friadent) immediately restored with provisional crowns following implant placement, noted two implants lost for an overall success rate of 88.2%.5 The author felt that using his protocol, narrow diameter implants (3.8 mm) increased the risk for nonintegration. However, in describing immediate restoration results in two groups of patients implanted either immediately after tooth extraction or in mature edentulous sites, Chaushu et al6 reported a success rate of 100% for the subset of nine consecutive single-tooth implants placed in mature alveolar sites using hydroxyapatite-coated cylindrical implants (six Steri-Oss HA-coated implants, Nobel Biocare, and three Alpha Bio HA-coated implants, Petah-Tikva, Israel) with diameters of 3.8 and 4 mm and lengths of 12 and 16 mm.
|Figure 1. Site selected for single-tooth implant placement and immediate restoration. Note presence of teeth on either side of selected site.|
At the University of Chicago, we have been immediately restoring single-tooth implants for more than 3 years. Patients are selected for this treatment protocol if they have mature single edentulous tooth sites located between healthy functional teeth (Figure 1). Adequate bone volume to permit the placement of an appropriate sized implant is required, or bone graft augmentation of the site prior to implant placement is performed.
On the day of surgery, the patient is pre-medicated with an oral antibiotic (1 g penicillin VK or 300 mg clindamycin) and an anti-inflammatory medication (600 mg ibuprofen) followed by two 1-minute oral rinses with chlorhexidine. Profound prolonged local anesthesia is obtained by using 2% lidocaine with 1:100,000 epinephrine and 0.5% bupivacaine with 1:200,000 epinephrine introduced via infiltration.
The soft tissue is reflected using a conservative papilla-sparing flap design. Alternatively, if sufficient attached mucosa is present, a tissue punch technique is utilized using a 4-mm latch handle punch mounted on a handpiece. The selection of either of these techniques is based on the goal of creating the best final soft tissue architecture for crown emergence profile and interdental papillary form while limiting tissue trauma.
|Figure 2. Implant placed into prepared site.|
The exposed site is scored with a round bur, permitting stable introduction of a 2-mm disposable pilot drill that is used to penetrate the bone to a depth of 10 mm. A periapical radiograph is taken with the pilot drill in place to verify the desired angulation and to check that implant placement will not encroach upon any important anatomical structures. After confirmation of proper position, the pilot drill is used to establish the final depth corresponding to the anticipated implant length. The bony site is then sequentially enlarged to the desired implant diameter. In maxillary sites where the bone is not dense (type 3 and 4),2 the final diameter can also be obtained using osteotomes. Sites are tapped only in denser bone (types 1 and 2).2 The implant is introduced to the prepared site and seated to the level of the crestal bone using a hand ratchet driver (Figure 2). Copious irrigation is utilized throughout the bone preparation phase, including the seating of the implant. Stability of the implant is assessed by the application of reverse torquing pressure to 35 Ncm using a hand-held torque wrench.
|Figure 3. Temporary implant abutment cylinder prepared in the mouth to receive the provisional resin crown.|
|Figure 4. Provisional resin crown cemented in place.||Figure 5. Periapical x-ray of implant with resin crown in place.|
Fabrication of the immediate provisional restoration begins by first screwing a temporary implant abutment cylinder into the implant. The abutment cylinder is then prepared using a high-speed handpiece and copious irrigation to create the proper occlusal clearance for placement of a provisional resin crown (Figure 3). The resin crown is fabricated in advance on a preoperative cast using a denture tooth of the appropriate shade that is hollowed to accommodate the implant abutment. Alternatively, a polycarbonate crown form can be used. The prefabricated resin crown is placed over the implant abutment in the mouth to confirm seating. It is then luted to the abutment using autopolymerizing tooth-shaded resin while retaining the access hole to the screw. The crown is unscrewed and adjusted to establish the desired occlusal and interproximal contacts. Revision is made as needed to maximize marginal fit to the temporary abutment, soft tissue support, and the emergence profile. The resin crown is polished and then finally screwed into place (Figures 4 and 5). The access hole is sealed with a temporary restorative material to facilitate ease of removal at a later date (Fermit temporary restorative material, Ivoclar Vivadent). Alternatively, the crown can be prepared as a cementable restoration and placed using a provisional luting agent (Improv Temporary Cement, Nobel Biocare).
|Figure 6. Postoperative healing following suture removal.|
Postoperative medications include oral antibiotics (500 mg penicillin VK qid for 1 week or 150 mg clindamycin qid for 1 week), oral analgesics as needed, and a chlorhexidine oral rinse (tid for 2 weeks). Patients are instructed to avoid masticating on this implant resin crown for 6 to 8 weeks, and then to chew only soft foods until the fabrication of the final restoration. They are further instructed not to brush the site for 2 weeks. Light brushing and flossing should then commence, with a return to routine brushing and flossing 4 weeks post-operatively. Patients are seen 2 weeks after surgery for follow-up evaluation. If sutures were placed, they are removed at this time (Figure 6). The patient is then scheduled for fabrication of the definitive restoration.
|Figure 7. Final ceramometal crown in place.||Figure 8. Aesthetic appearance with definitive restoration in place.|
In the original protocol, fabrication of the definitive implant crown began at 3 months (for the mandible) or 6 months (for the maxilla) following surgery. Based on experience, the protocol has been revised, and final crown fabrication begins about 8 weeks postoperatively in most cases. This ceramometal restoration is made in the standard fashion using either cement or screw-retention in order to maximize the aesthetic result (Figures 7 and 8). Care is taken at this time to lessen occlusal contacts on the restoration relative to the adjacent dentition using articulating ribbon and 8 µm shimstock.
RECENT CLINICAL EXPERIENCE: PRELIMINARY RESULTS
Based on our successes with immediate restoration of single-tooth implants, we decided to investigate this protocol in a controlled fashion. A prospective clinical trial has been initiated to assess the long-term safety and effectiveness of immediately restored implants over time as compared to the standard waiting periods for osseointegration. A total of 50 subjects with unrestored single-tooth edentulous sites are planned for enrollment (25 maxillary sites, 25 mandibular sites) in accordance with institutional review board guidelines and after obtaining informed written consent. Each subject is to undergo implant placement using a commercially available endosseous dental implant (Replace Select hydroxyapatite-coated implant, Nobel Biocare) with same day placement of a provisional resin crown.
To date, 38 subjects have been enrolled into this clinical trial, with implant placement and restoration of 23 maxillary sites and 15 mandibular sites. The most commonly treated maxillary sites have been first and second premolars, with the first molar site being most commonly treated in the mandible. The implants most commonly used in the maxilla have been 3.5 and 4.3 mm in diameter and 13 mm in length. Implants of 5 mm in diameter and 13 mm in length have been the most commonly used in the mandible.
At the time of this report, all 38 implants are in place and stable. The range of follow-up is 2 to 18 months (mean of 8.2 months). One soft tissue complication has been observed in one patient (peri-implant tissue hyperplasia). This complication was successfully treated by excising the hyperplastic tissue and reinforcing oral hygiene practices. No crestal bone loss was observed radiographically for this subject.
Twenty-five of these 38 subjects have had a ceramometal fixed restoration placed, with 12 subjects having returned for the first 6-month follow-up. Bone height has been maintained in all cases as assessed by peri-implant probing and periapical radiographs. All 25 implant-retained ceramometal crowns currently remain in function without complication. Soft tissue aesthetic form has been well maintained. All subjects will continue to be examined at 6-month intervals over a 3-year period to assess integration maintenance and function of the restoration. Patients have subjectively rated the results, indicating that immediate restoration was a valuable benefit when compared with the restoration delay that occurs with the standard protocol.
Hydroxyapatite-coated implants were selected for use in this study with the intention of enhancing the potential for rapid integration, however, we anticipate that this protocol will show equally good results with the use of implants having other surface types. Good implant stability at the time of placement appears to be the best predictor of success for immediate restoration. We have employed this protocol in our clinical practices using implants with machined titanium surfaces and have achieved the same level of results.
Based on the results to date, we anticipate that immediate restoration of single-tooth implants will become a standard treatment option for eligible patients, with the placement of a provisional crown on the day of implant surgery. The fabrication of a definitive crown will occur after adequate soft tissue healing. Further studies are now planned to examine combining immediate restoration of single implants with immediate implant placement on the same day that the single tooth is extracted. This will further reduce the overall time required for treatment.
1. Misch CE. Contemporary Implant Dentistry. 2nd ed. St. Louis, Mo: CV Mosby; 1999:3-12.
2. Branemark P-I, Zarb GA, Albrektsson T. Tissue-Integrated Prostheses. Osseointegration in Clinical Dentistry. Chicago, Ill: Quintessence Publishing Co, Inc; 1987:202, 214-228.
3. Wohrle PS. Single tooth replacement in the aesthetic zone with immediate provisionalization: fourteen consecutive case reports. Pract Periodont Aesthet Dent. 1998;10:1107-1114.
4. Kan JY, Rungcharassaeng K. Immediate placement and provisionalization of maxillary anterior single implants: a surgical and prosthodontic rationale. Pract Periodont Aesthet Dent. 2000;12:817-824.
5. Johnson MW. Criteria for immediate anterior implant placement and early provisionalization. Academy News (Academy of Osseointegration quarterly publication). 2000;11:1-8.
6. Chaushu G, Chaushu S, Tzohar A, et al. Immediate loading of single-tooth implants: immediate versus non-immediate implantation. A clinical report. Int J Oral Maxillofac Implants. 2001;16:267-272.
Dr. Toljanic is a prosthodontist and an associate professor at the University of Chicago, Section of Dentistry where he is also the director of research. He has conducted clinical trials and published a number of articles in the area of implant rehabilitation. Dr. Toljanic maintains a part-time private practice with a focus on implant prosthodontics.
Dr. Baer is an assistant professor at the University of Chicago as well as the founder and academic director of The Chicago Center for Advanced Dentistry in Moscow, Russia, a training center for implantology. Dr. Baer has lectured extensively on all aspects of implantology.
Disclosure: The clinical trial referred to in this report is supported by a grant from Nobel Biocare, Yorba Linda, Calif.