Discussion

Several surgical procedures for the treatment of peri-implantitis could be found in literature. Nonsurgical therapy might be effective in the treatment of peri-implant mucositis. Furthermore, the adjunctive use of antimicrobial mouth rinses may enhance the outcome of the mechanical debridement in case of peri-mucositis. In peri-implantitis lesions however, nonsurgical therapy was found to be less effective. For this reason, surgical therapy and adjunctive local or systemic antibiotics may cooperate in the reduction of BOP and PD parameters [17]. Attempts have been made to determine the optimal conservative, regenerative, or resective surgical protocol to achieve the complete resolution of peri-implantitis, including the regeneration of lost tissues and the hypothetical reestablishment of osseointegration along previously contaminated implant surfaces, as described in the present case report. In these terms, bone defect configuration seems to play a key role concerning the clinical outcome following a surgical regenerative approach of peri-implantitis lesions, as suggested by Schwarz et al. [12]. Defects characterized by a deep vertical component with the buccal and lingual bone plates preserved have a more predictable outcome following regenerative therapy, as confirmed by the present case

In this report, topical application of tetracycline solution for implant surface decontamination has proven to be an effective treatment option when coupled with bone regenerative procedures, as demonstrated by the long-term follow-up. Tetracyclines are broad-spectrum agents, exhibiting activity against a wide range of gram-positive and gram-negative bacteria, inhibiting protein synthesis by preventing the attachment of aminoacyl-tRNA to the ribosomal acceptor (A) site. The favourable antimicrobial properties of these agents and the absence of major adverse side effects have led to their extensive use in the therapy of human infections [18]. On the other hand, it was demonstrated that the development of resistance mechanisms may reduce the effectiveness of the molecule [19]. Even if tetracyclines in dentistry can be administrated systemically, recent trials indicated that locally delivered antimicrobials might enhance the effects of periodontal surgical therapy and reduce the signs of peri-implantitis [20]. The topical use in previously infected natural pockets has to be preferred, in order to reduce the probability of exogenous reinfection during the healing period [21]. Tetracyclines are released at effective concentrations over 7 days, and significant reductions in anaerobic pathogens up to 60% could be sustained for 6 months posttreatment [22]. Tetracycline fibers were originally applied topically in the treatment of periodontal diseases: affected sites had fibers placed to the depth of periodontal pockets, maintained in place by superficial applying of cyanoacrylate adhesive. Subsequently, the local use of tetracycline showed positive effects on clinical and microbiological parameters in the treatment of peri-implantitis [23]. Actually, this class of antibiotic showed improved clinical results when involved in the treatment of peri-implantitis in conjunction with bone grafts filled into the defect-24-

The choice of the graft material deserves some words to be spent. A wide selection has been used over the years for the treatment of peri-implantitis. The majority of peri-implantitis cases found in literature and treated with graft materials alone were located in the mandible. Although some failures were reported, most of the treatments generally resulted in improved clinical results. The studies by Behneke et al. included multiple defects approached by means of autogenous bone grafts with observation intervals extending for some cases up to 3 years [13, 25, 26]. Notable reductions of PD coupled with significant radiographic bone fill were reported. Out of the 25 consecutive lesions treated, failure and graft removal was reported only for two lesions. Other four lesions showed flap dehiscences within 2-3 weeks after grafting, which healed following chlorhexidine rinses or osteoplasty [13]. Guided bone regeneration may constitute a predictable way to treat osseous peri-implant defects improving soft tissues condition as well. Most of the studies concerning the treatment of peri-implantitis comprehended those in which a combination of grafts and barrier membranes was used. The submerged approach was used in half of these studies to allow for undisturbed healing and to reduce the risk of infection. From the results it was evident that the submerged approach was not always successful in practice, as the most common complication was the membrane exposure. A comparative study published by Khoury and Buchmann evaluated the use of autogenous bone grafts alone or associated with both bioabsorbable and nonresorbable membranes in a submerged approach. The results showed no significant differences between the groups in terms of treatment outcome after 3 years; however complications quite often occurred when membranes were used-14-

A study by Schwarz et al. evaluated the healing of intrabony peri-implant defects following application of a nanocrystalline hydroxyapatite paste or DBBM in combination with resorbable collagen membranes. Clinical parameters were recorded at baseline and after 6 months. Results showed that both treatments led to improved clinical conditions [27]. Recently, a study by Roos-Jansåker et al. compared two surgical techniques using a bone substitute with or without the application of bioabsorbable membranes adopting a nonsubmerged approach. According to Khoury et al. no significant differences were observed between either group [14, 15]. It could be concluded that the placement of membranes in addition to bone grafting does not provide any adjunctive effect. Considering the present case report, at the time of intervention much of this knowledge was still unknown; however it could be assumed that the presence of a bioabsorbable membrane may have promoted an undisturbed graft remodelling, permitting a new bone formation due to the creation of a secluded space over the graft against the ingrowth of soft tissue cells surrounding the defect. Moreover, differently from nonresorbable membranes, the bioabsorbable collagen membrane used in the present clinical case may have decreased the risk of membrane exposure, allowing an uneventful healing as demonstrated by the 6-month recall visit

Peri-implant disease treatment is still a controversial topic, as several authors provided different therapeutic solutions [28]. A correct diagnosis represents the first and most important step in order to schedule an adequate treatment and its relevance is univocally acknowledged. In 2004 Lang et al. published important guidelines based on a diagnostic-therapeutic algorithm [29]. In presence of a severe level of the disease, in addition to the implant surface decontamination and antibiotic therapy, a surgical approach should be performed. When regenerative treatment is chosen, the use of a barrier membrane technique, even in combination with bone substitutes like DBBM, is recommended

Conclusion

The results obtained in the present report stressed the importance of a combined antibiotic and mechanical decontamination associated with a regenerative procedure in the treatment of seriously compromised implants. This treatment led to positive effects on the clinical and radiological parameters over a long-term follow-up timespan

References