Introduction

The use of dental implants for the treatment of edentulous and partially dentate patients with fixed prostheses has increased in recent years.1 However, despite a high rate of success, some implants fail. The incidence of dental implant fractures is between 0.16% and 1.15%.2 Implant fracture has 2 main causes. First is the adverse occlusal load that may result in mechanical complications.3 Overloading can be a consequence of patient physiologic alterations (eg, parafunctional activity, bruxism) or can have a prosthetic origin, for example, an inadequate occlusion, the presence of distal extensions or cantilevers in implant-supported prostheses, and lack of passive fit of the prosthesis over the implants.

The other cause of implant fracture is peri-implant vertical bone loss, attributable to both chronic peri-implant inflammation and occlusal trauma.4 

The authors used the apicoectomy approach to retrieve implant fragments not visible in the alveolar arch and to preserve as much bone as possible for the placement of new implants. Creation of a lateral bone breach similar to a window permitted good visualization of the bone condition while avoiding excessive destruction of the maxillary bone, which is usually a consequence of other techniques.

The apicoectomy technique is a surgical root approach used to preserve the tooth any time this is possible. To complete a good procedure of primary importance, one must have anatomic knowledge because all depends on correct localization of the root apex. Radiography can help to localize the apex. Then, a full-thickness flap is used to achieve the best location and isolation of the operatory field, and the detachment is executed. The location of the apex is easy to locate after the detachment has been performed, especially when fenestrations or bone swelling is present; in other cases, it is necessary to use the drill to take away the cortical bone above the lesion.5 The basic surgical procedure includes resection of the root tip (apicoectomy) and periapical curettage. The root canal is exposed and may be treated from the apical, retrograde direction. In this way, it is also possible to remove a cyst or granuloma, with management of the apex during retrograde filling in amalgam.

Apicoectomy and retrograde root end filling are performed in the presence of periapical pathosis when conventional root canal treatment has failed. The aim of the procedure is to separate the contaminated internal environment of the root canal from the external environment, thus allowing healing to take place.6,7 

The technique of retrograde canal treatment can be used always when the orthograde procedure is unsuccessful, or when it is necessary to remove a granuloma or a cyst that developed around the tooth apex through the same opening, and otherwise in cases in which the apical part of the root canal is inaccessible for conservative treatment. Surgery offers the possibilities of removing inflamed periapical tissue and, more important, of improving the cleaning, shaping, and sealing of the apical portion of the root canal.

In this case, the apicoectomy technique was performed to get the apexes of fractured implants, avoiding big destruction of maxillary bone useful for new immediate implant rehabilitation.

Case Report

A 72-year-old male presented with an implant-anchored maxillary prosthesis that had become unstable. This had been constructed by his previous dentist, who had placed 7 implants into the maxilla and had cemented the patient's existing prosthesis (3 pieces) over the newly placed implants. The patient, not understanding the reason for the problem, complained of loss in retention of the prosthesis. This instability was caused by bone resorption leading to consequent implant fractures.

Inadequate rehabilitation using the previous prosthesis fixed by resin gave rise to an incorrect occlusal load and chronic periodontal disease, with consequent implant fractures and subsequent abscesses. The procedure utilizing the previous prosthesis was incorrect because occlusal forces were not well imparted on the implants and were overloaded in some points, and the acrylic resin stabilizing the prosthesis created fissures between gingiva and prosthesis where the hygiene was too difficult and the bacteria could grow up. In this way, both the bad occlusal load and periodontal infection contributed to the implant failure. In fact, malocclusion due to an inadequate prosthesis cemented with acrylic resin and the difficulty of dental hygiene by reason of overflowed resin material caused cooperation of bacterial infections and bad occlusal load—the 2 main factors causing implant failure.

The first step consisted of removal of the fixed prosthesis and fractured implants, leaving the osseointegrated implant apexes in the maxillary bone. The patient, having had a past experience of surgical complications, did not want to undergo more surgical treatment. For this reason, the author decided to try a removable prosthesis, but the patient wore this for 3 months with poor compliance. Moreover, many cases of recurrent sinusitis were due to an implant apex in the maxillary sinus.

Therefore, the program was to remove the old implants and insert new ones. Before surgery, the prosthesis was taken off and the patient was given suitable antibiotic treatment (amoxicillin 875 mg + clavulanic acid 125 mg; tablet 1 g twice a day for 7 days). A preoperative orthopantomography (OPT) was performed (Figure 1).

Figures 1–6.

Figure 1. Preoperative orthopantomography with osseointegrated implant apexes, one of which is positioned inside the right maxillary sinus. Figure 2. Implant apex inside the maxillary sinus. Figure 3. The bone window is used (fixed with 1.2-mm-diameter microscrew) to establish a partition wall between the maxillary sinus and the new implants. Figure 4. New implant replacement. On the left, the sinus membrane was unbroken. Figure 5. Fixed prosthesis and esthetic resin cover on #24. Figure 6. Postoperative orthopantomography after 1 year. On the right is the microscrew used for bone fixation.

Figures 1–6.

Figure 1. Preoperative orthopantomography with osseointegrated implant apexes, one of which is positioned inside the right maxillary sinus. Figure 2. Implant apex inside the maxillary sinus. Figure 3. The bone window is used (fixed with 1.2-mm-diameter microscrew) to establish a partition wall between the maxillary sinus and the new implants. Figure 4. New implant replacement. On the left, the sinus membrane was unbroken. Figure 5. Fixed prosthesis and esthetic resin cover on #24. Figure 6. Postoperative orthopantomography after 1 year. On the right is the microscrew used for bone fixation.

Surgical treatment under general anesthesia was performed to remove the 7 implant fragments, while preserving the bone and inserting 8 implants at the same time. We performed a mucosal incision on the alveolar maxillary crest and raised a mucoperiosteal flap, then created 2 bone lateral breaches (one on the right and other on the left) to get directly at the fractured implants.

On the right, the patient presented with recurrent sinusitis due to an implant apex as a foreign body perforating the sinus membrane. The Schneiderian membrane was broken during the first operation 7 years before, and, because of chronic sinusitis, it was fragile and adherent to the bone. To restore the sinus and increase bone height, we reconstructed a bone floor under the right sinus using the bone-like window created at the beginning and inserted bone chips to increase alveolar height (Figure 2). The bone window was utilized in a different place to establish a partition wall between the maxillary sinus and the new implants, adding horse hydroxyapatite (BONITmatrix synthetic resorbable bone graft materials, 0.6 × 4 mm; Competence Network BalticNet-PlasmaTec, Greifswald, Germany) and a resorbable membrane (Hypro-Sorb F collagenous resorbable membranes type I; Hypro Ortrokovice, sro, Pristavni, Česká Republica) to cover the same opening (Figure 3). Consequently, we were able to avoid apexes inside the sinus, because the Schneiderian membrane was broken from the previous fractured implant.

The maxillary sinus membrane on the left was undamaged, so after the apicoectomy approach was used, it was possible to remove the pieces of implants, insert new implants with hydroxyapatite and resorbable membrane, and put back the bone opened like a window in the original place; the breach on the apex of the new implant was then closed (Figure 4). A small piece of bone was first pulled up to get to the fractured implant apex. At the end of this procedure, the position of this piece of bone was possible in the same place, covering the apex of the new implant.

The apicoectomy approach allowed us to find the fragments and obtain a broad view from which to manage the membrane laceration of the right maxillary sinus and the amount of available bone. Moreover, this technique, instead of the other methods usually employed, enabled us to preserve the large quantity of bone necessary for the placement of new implants.

We used the Stryker TPS drill (Stryker, Kalamazoo, Mich) and a ready-made surgical splint as a guide to place 8 Camlog implants (Camlog US, Carlsbad, Calif) with an acid-etched surface in the maxillary arch. This splint was constructed using a wax model and reproducing the occlusion to produce a resin device as a surgical guide.

The implants were 4 on the right and 4 on the left, with the following dimensions: the first implant was 4.3 × 11 in the #8 site, the second was 4.3 × 13 in the #6 site, and 2 implants were 4.3 × 9 in the right posterior region. On the left, an implant was 3.8 × 11 in the #9 region, another was 4.3 × 11 in the #11 site, and 2 implants were 4.3 × 9 and 4 × 11 in the posterior region. Approximately 2 cm3 of hydroxyapatite small pieces (BONITmatrix) were inserted in both sides.

After experimental studies published by Boyne and James8 and Tatum9 regarding grafts in the maxilla, several new procedures and studies have documented the use of different implants and grafting materials.10,11 Even if autogenous bone is considered the gold-standard reconstructive material in bone augmentation, because of its osteoinductive and osteoconductive properties, more complex surgeries, including bone harvesting done intraorally and extraorally, are not suitable in all patients. In fact, several disadvantages are known, including donor site morbidity, limping if the graft is taken from the iliac crest, prolonged healing, the need for general anesthesia and hospitalization, increased cost of treatment, and unpredictable resorption of the graft. Many bone substitutes have been tried to find a good alternative to autografts, but even the best among them are only osteoconductive materials (eg, hydroxyapatite, allografts, xenografts, alloplastic materials). These materials maintain the original volume during the substitution process.12,13 Alloplastic bone graft materials such as porous hydroxyapatite, tricalcium phosphate, and bioactive glass have shown promising results in the sinus augmentation procedure.14 However, bone formation takes several months and is delayed in comparison with autologous bone owing to the osteoconductive—but not osteoinductive—properties of these materials. Anyway, although bone substitutes show only minimal osteoinductive potential, they may act as a scaffold for bone growth.15,16 Hydroxyapatite ceramics have the ability to induce mesenchymal cells to differentiate toward osteoblasts, rendering hydroxyapatite as a potential scaffold material for bone tissue engineering.17 

At the end, a hermetic suture of the mucosal wound by single resorbable stitches was performed (Ethicon Vicryl resorbable suture 4-0; Ethicon Inc, Somerville, NJ). In this phase, we made a provisional prosthesis, modified every 15 to 20 days, so a normal social life was possible for the patient. It was a removable resin prosthesis modified by soft material.

We later uncovered the implants using a crestal incision and put in the healing screws. A vestibular placement flap was made to keep implants in the attached gingivae on the right side; the other part was sutured around every implant. After mucosal healing was complete, we took an impression. We later carried out an esthetic test using a provisional prosthesis to get an idea of the shape of the teeth. For this procedure, we used the Whip Mix articulator (Whip Mix Corporation, Louisville, Ky). The fixed palladianum prosthesis with an external surface in composite material was later used. Palladianum was chosen because it is less expensive than gold. The composite material was chosen for reasons of occlusal impact, because it is less abrasive; the patient suffers from bruxism and did not want the lower arch to be restored. Dental porcelain has been described as wear resistant but extremely hard and abrasive against opposing enamel and other restorative materials. Rough-ground porcelain surfaces produce excessive antagonistic tooth wear. Porcelain is more abrasive than gold, amalgam, composite resin, and enamel.18,19 For this reason, we chose the composite material prosthesis for this patient affected by bruxism.

Finally, we completed treatment with a resin metal-free crown on #24 (Figure 5). The OPT after 1 year from surgical treatment shows good osseointegration of the 8 implants, which coincides with the clinical presentation of a good surgical outcome (Figure 6).

Conclusion

In the literature, 2 main treatment modalities have been proposed for the removal of foreign bodies in the sinuses20: (1) an intraoral approach with the creation of a bony window in the anterior-lateral wall of the maxillary sinus,21 which can be used endoscopically22 as well; and (2) a transnasal approach with functional endoscopic sinus surgery.23 In our case, the endoscopic approaches could not manage an implant apex that perforated the sinus because a portion was osseointegrated. For this reason, we created on the right a bony window in the lateral wall of the sinus to get to the implant apex and remove it. Moreover, to manage the other fractured implants, we needed to get to the maxillary bone under the sinus and remove the osseointegrated apexes. So we had to find another technical solution.

The standard way to remove unsuccessful implants involves the probing technique, which utilizes a circular drill bigger than the implant diameter to remove the osseointegrated device. If the aim is to place a new implant in the same location, the external diameter of the drill must be taken into account, to insert an implant with a larger diameter and thus ensure primary stability. The problem is that this technique removes copious quantities of bone while trying to overcome the force of osseointegration, leading to the destruction of bone surrounding the implant and making the placement of new implants often impossible. The other limit of this procedure is the difficulty of removal when the implants are not visible on the alveolar crest. Another solution consists of removal of the coronal component of the fractured implant, while leaving the remaining apical fragment integrated within the bone. If additional implants prove necessary, they can be placed elsewhere in accordance with existing anatomic possibilities.2426 

In this case, it was important to remove several fractured implants while keeping the bone suitable to plan an immediate implant rehabilitation.27 Moreover, the fractured apexes were invisible by intraoral examination, and removal by drill would have destroyed a big quantity of bone. The implants could have been left in situ in the absence of symptoms, but this would have prevented the scheduled rehabilitation. The apicoectomy technique allowed a good visual field to get to fractured implants without destruction of the alveolar bone below and to evaluate the state of the bone for placement of new implants. Moreover, this approach permitted removal of the implant in the sinus and management of the perforated sinus membrane. Immediate rehabilitation with 8 new implants and insertion of hydroxyapatite and resorbable membrane was performed.

Abbreviation

     
  • OPT

    orthopantomography

References

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