In this report, a case is presented in which a patient received eight implants 10 months after tooth extraction and socket preservation. The implants were placed in both arches (maxilla = 4, mandible = 4) and immediately loaded using fixed partial restorations; they remained functional over 5 years. No changes in bleeding on probing or plaque index were observed; however, a 1.5-mm probing attachment level loss was observed during the first 3 years (mean: 0.25 mm/year) with no subsequent changes.
The field of implant dentistry has expanded recently due to progress in regenerative procedures and bone biology research, as well as the development of new biomaterials. Dentists and their patients are not only concerned with the functionality and esthetics of implant restorations, but also with the timing of implant loading and care of the implants. The successful immediate loading of dental implants with fixed restorations to restore completely or partially edentulous maxillae and mandibles has been demonstrated.1,2
Due to successful preventative and educational programs, preservation of dentition and esthetics have become important motivators for young adults to seek dental treatment. Older adults are often confronted with advanced periodontal disease and tooth loss.
Alveolar ridge resorption following tooth extraction is a frequently observed phenomenon that can impair dental implant placement. The advent of guided bone regeneration has provided clinicians with a method to limit this condition.3 Current methods of preventing ridge resorption include the use of particulate autografts, allografts, alloplasts, xenografts, and resorbable or nonresorbable membranes manufactured from various materials.4–8 While the successful use of these techniques to preserve sufficient bone to allow for implant placement has been demonstrated,8 limited data exist to determine the degree to which implant survival may be impaired in regenerated extraction sockets or the best timing for implant loading in these cases.
In the case reported here, implants were placed into sites after socket preservation with nonresorbable membrane barriers. The implants were immediately loaded with fixed restorations, and implant success was monitored over a 5-year span.
The patient (female, 54 years old, nonsmoker, no systemic diseases) presented in July 2004 with severe pain and spontaneous gingival bleeding, halitosis, and multiple periodontal abscesses. The intraoral examination was limited by the severe pain caused by palpation of the teeth and gingiva. Significant soft and hard deposits were present (Figure 1a through c). Generalized severe bone loss was observed radiologically in both the maxilla and the mandible (Figure 1d).
The patient reported that she had been treated with a removable telescopic crown-retained partial mandibular denture about 2 years earlier and indicated that she had not removed the denture during daily tooth care since the time of insertion, as recommended by her dentist. The remaining maxillary teeth were used as abutments for fixed partial dentures (FPDs). Teeth numbered 2, 3, and 6 as well as teeth numbered 12 and 14 were used as abutments for FPDs, while teeth numbered 7–11 were restored with individual crowns (Figure 1a through c). In the mandible, a telescopic crown-retained removable denture had been placed, with teeth numbered 18–20, 22, 23, 26–28, and 31 used as abutments (Figure 1d).
Surgery, augmentation, and provisional restoration
Full-thickness access flap surgery was performed simultaneously with extractions and socket preservation in the maxilla and mandible. As requested by the patient, surgical treatment was conducted under full anesthesia. Probing pocket depth (range 8 to >12 mm) and bleeding on probing (BOP, 100%) were intraoperatively measured and recorded.
In the maxilla, teeth numbered 2 and 12–15 were extracted, and teeth numbered 3 and 6–11 were preserved. The vertical bone defect on the mesial site tooth number 3 was regenerated with a 1:1 mixture of xenograft, (Bio-Oss spongiosa 0.25–1 mm, Geistlich Biomaterials, Wolhusen, Switzerland) and autogenous spongiosa, harvested from the retromolar pad, then covered with an absorbable barrier (Bio-Gide, Geistlich Biomaterials).7
After removing the mandibular restoration, teeth numbered 22, 23, 26–28, and 31 were extracted (Figure 2a), and endodontic treatment was performed on tooth number 20, while teeth numbered 18–20 were preserved. Two immediate provisional implants (IPIs, Nobel Biocare, Cologne, Germany) were placed in area number 24 and area number 30 to support the temporary removable restoration (Figure 2b).
Socket preservation was performed as previously described.8,9 Briefly, an intrasulcular incision extending to the adjacent teeth was made, and a full-thickness flap was elevated. No vertical releasing incisions were made. The teeth were extracted, and the socket was carefully debrided and irrigated with sterile saline solution. The socket was then covered with a nonresorbable dense polytetrafluoroethylene (dPTFE) membrane (Cytoplast, Osteogenics Biomedical Inc, Lubbock, Tex) that covered at least 50% of the buccal and lingual bone plate of the extraction socket in the vertical plane. The dPTFE membrane was applied alone without the use of soft or hard tissue grafts, and no further steps were taken to secure it in place. The membrane covering the temporary implant site was pierced with a scalpel in the area in which the implant was to be placed. The flap was repositioned and sutured in place with interrupted sutures (Figure 2c and d).
The patient received temporary removable restorations 1 day after surgery (Figure 3a through d). A partial removable denture was fabricated for the maxilla. The base of the prosthesis had no direct contact with the soft tissue in regions numbered 12–14 during the first 10 weeks to prevent masticatory pressure on the augmented area (Figure 3b). In the mandible, the suprastructure was retained with primary and secondary telescopic crown attachments in regions numbered 18–20 and prosthetic teeth from numbers 21–30 (Figure 3a through d; Figure 4). To prevent any significant pressure on the augmented area, the interim prosthesis was also supported on the IPIs.
Five months after the initial surgery, the gingival recessions in areas numbered 6–11 were covered with a connective tissue graft according to the trap-door approach described by Edel.10
Four months after coverage of the gingival recessions (ie, 9 months after socket preservation), the patient fractured teeth numbered 10 and 11 in a domestic accident. As a result, these 2 teeth were extracted. A screw cylinder dental implant (Straumann, Waldenburg, Switzerland) was immediately inserted in area number 10 (Table). The socket number 11 was augmented using the socket augmentation procedure described above.8,9 An immediate implant placement in area number 11 was not performed because of a fracture of the buccal alveolar wall.
Sinus augmentation and simultaneous implant placement were performed 10 months after socket augmentation. Sinus augmentation was performed in area number 13 using a 1:1 mixture of xenograft, (Bio-Oss, Geistlich Biomaterials) and autogenous spongiosa, and the access window was covered with an an absorbable barrier (Bio-Gide, Geistlich Biomaterials).11 Seven screw cylinder dental implants (Straumann) were placed (maxilla N = 3, mandible N = 4) using a 1-stage surgical approach (Table). Following full-thickness flap elevation, implant site preparation was performed at 875 rpm, and implants were manually placed at a torque of 35 Ncm. After an impression was taken (see below), healing caps were placed on the implants.
Medication and postoperative care
Clindamycin (ratiopharm, Ulm, Germany), 600 mg once daily for 6 days, as well as diclofenac as an analgesic (Novartis Pharma, Nürnberg, Germany), 100 mg once daily for 4 days were administered starting 1 day before surgery. In addition, the patient was advised to use a 0.1% chlorhexidine digluconate rinse (Chlorhexamed Fluid, GlaxoSmithKline, Buehl, Germany) twice daily for 4 weeks.
Sutures and membranes were removed 10 days and 4 weeks, respectively, after surgery. The prosthesis base was relined using a soft vinyl polysiloxane liner (GC reline soft, Leuven, Belgium) 10 weeks after surgery.
From the time of membrane removal until prosthetic restoration, the patient was enrolled in a monthly supportive periodontal therapy program.
Following implant insertion and repositioning of the soft tissue, teeth were prepared with a chamfer, and impressions were taken of the natural teeth and implants. A closed tray impression technique with a polyether impression material (Impregum, 3M ESPE, Neuss, Germany) and pick-up impression parts was used (Straumann).
Customizable parts (SynOcta, Straumann) were used to fabricate gold implant abutments (Portadur P4, Au 68.50%, Wieland, Pforzheim, Germany). After casting, the implant abutments were ground and polished.9 Each abutment's screw opening was filled with a single-component light-cured resin (Fermit, Ivoclar Vivadent, Schaan, Liechtenstein) (Figure 5). A CoCrMo alloy (Ankatit Laser, Ankatit-Anka Guss, Waldaschaff, Germany) was used for casting of the suprastructure, and porcelain (Vintage, Shofu Dental, Ratingen, Germany) was used for veneering.
Five days after implant placement, the natural teeth and implants were loaded with FPDs that were placed in centric occlusion and fixed using a temporary cement (TempBond, Kerr, Bioggio, Switzerland).
In the maxilla, the area of teeth numbered 3–5 was restored with an FPD on implant number 5 and natural tooth number 3. For the natural abutment tooth, a protective electroformed gold coping with a thickness of 0.25 mm was fabricated (AGC Galvanogold, Wieland) as previously described,12,13 placed on the abutment, and permanently fixed using a zinc phosphate cement (Harvard Cement, Harvard Dental, Berlin, Germany). The FPD connecting the natural tooth number 3 and the implant number 5 was placed using a temporary cement (TempBond, Kerr, Orange, Calif). The teeth numbered 6–9 were restored with single crowns. The implants numbered 10, 12, and 13 were restored with an FPD having a cantilever of 1 premolar width in area number 14 (Figure 6a through d).
In the mandible, the natural teeth numbered 18–20 were restored with single crowns, and the implants numbered 21, 28, 30, and 31 were restored with an FPD.
The patient was enrolled in a postoperative maintenance program consisting of semi-annual follow-up appointments. At the follow-up visits, oral hygiene instructions were given and subgingival and supragingival debridement were performed. The first maintenance visit (BSL) was performed 3 months after restoration placement.
BOP, probing attachment level (PAL), and clinical attachment level (CAL) were measured using the same periodontal probe (UNC 15, Hu-Friedy, Leimen, Germany). PAL and CAL were recorded for the 4 sites of implants and natural teeth, respectively, and were averaged. PAL was defined as the distance (mm) between the deepest point of the peri-implant pocket and the smooth neck section of the implants. CAL was defined as the distance (mm) between the deepest point of the pocket and the cementoenamel junction or the FPD margin. The presence or absence of plaque14 was measured with a plaque revelator (Mira-2-Ton, Hager & Werker, Duisburg, Germany). Measurements are reported for BSL and at 1, 2, 3, and 5 years after loading.
All 8 implants remained functional throughout the 5-year observation period. Statistical analysis of the clinical measurements was not performed due to the small number of implants. However, no major changes were found between examinations (BSL to 5 years) in BOP or plaque index values (range: 2% to 4% for both parameters). Radiographic evaluation showed stable bone levels for all implants and teeth. PAL outcomes for the 8 implants showed a deterioration from BSL (mean = 0.5 mm) of 1.5 mm during the observation period (1 mm at 1 year and 1.5 mm at 3 years). No changes in PAL outcomes were observed between years 1 and 2 or between years 3 and 5. Further analysis of the data showed PAL losses of 1 mm during year 1 and between years 1 and 3, yielding a mean PAL loss of 0.25 mm per year. After the third year, no further PAL loss could be determined based on the method of measurement used. CAL outcomes of natural teeth were stable (range: 2 mm to 2.5 mm) during the 5-year observation period (Figure 7).
Bone regeneration and immediate implant loading have been extensively studied in recent years.1,2,4–6,8,9,15 Although many positive results have been published, several clinical issues remain unresolved. Clinicians would benefit from knowing whether it is appropriate to place implants in regenerated bone and what the optimal time to do so might be; the timing and methods of implant loading and care are also important factors to be considered.
The results of the case presented here correspond with those of a recently published case study that used a delayed loading protocol and restoration with telescopic crowns as attachments.9 Our results also agree with those of a prospective clinical study that evaluated the 5-year survival (100%) and success rates (98.3%) of 66 implants placed in bone that had been previously augmented with autografts and nonresorbable barrier membranes.16 In the case reported here, barrier membranes were used without additional graft material. This resulted in sufficient preservation of bone volume to allow for implant placement. The use of nonresorbable dPTFE membranes for socket preservation has been described previously.8,9,17 In the first study mentioned, it was demonstrated both clinically and histologically that the use of these membranes alone without any graft material leads to the formation of a sufficient amount of vital bone.8 It was demonstrated in a recent study that implant survival and success rates inserted into bone regenerated in this manner are similar to implants placed in native bone irrespective of the loading protocol used.16,17 It was demonstrated in a recent study17 that survival and success rates of implants inserted into bone regenerated in this manner are similar to those of implants placed in native bone irrespective of the loading protocol used. All 8 implants in the present case remained successfully integrated after 5 years, with survival and success rates of 100% and PAL loss comparable to that of implants placed in healed bone and and loaded at a later time point.17,18
The major disadvantage of the method of socket preservation used in this case study is the relatively long time necessary before implant placement and subsequent loading is possible.
Bone regenerated using nonresorbable dPTFE membranes alone without the use of soft or hard tissue grafts has a load-bearing capacity similar to nonregenerated healed bone, and osseointegration of implants placed therein can be expected. Implants placed into bone regenerated using this protocol and immediately occlusally loaded with FPDs have a success rate comparable to that of implants loaded according to a nonocclusal loading protocol.