Reversible and Irreversible Peri-implant Lesions: Report and Etiopathogenic Analysis of 7 Cases

Occlusal Schemes for Implant Restorations: Best Evidence Consensus Statement

PURPOSE

Numerous studies have focused on the various complications with implant-retained restorations and a common thread in these publications is the potential for occlusal overload. The purpose of this Best Evidence Consensus Statement on implant occlusal schemes was to review the literature to determine the level of scientific evidence upon which the articles are based.

MATERIALS AND METHODS

Limiting the search to Clinical trials, Randomized Controlled Trials, Systematic Reviews, Meta-analyses, the key words: dental implants, occlusion, found no citations. Expanding the search to Journal articles found 1,483 results, 20 of which pertained to the question. Doing a similar search including Journal Articles, the key words: dental implants and occlusal scheme found 47 citations, 17 of which were pertinent to the question.

RESULTS

After eliminating duplicates and non-relevant articles, 15 were included in the review. Nineteen additional articles were culled by going through the reference lists in the aforementioned articles.

CONCLUSIONS

There is a lack of scientific evidence regarding the occlusal scheme utilized with implant restorations that will minimize or eliminate complications. In light of this lack of scientific evidence, the style of occlusion a practitioner utilizes with tooth or mucosal supported prostheses may be used with implant-supported restorations until compelling evidence dictates otherwise.

Degenerative and regenerative morphological aspects in peri-implantitis

The purpose of this study was to describe the tissues surrounding two early failed dental implants morphologically and ultrastructurally. In the first case, the implant's surface was analyzed by scanning electron microscopy (SEM) using an environmental scanning electron microscope and the surrounding tissues were analyzed by light microscopy (LM) and transmission electron microscopy. In the second case we used only LM. By SEM analysis, very thin connective tissue was seen at the implant's apex; in the middle part, highly vascularized connective tissue and poorly mineralized areas were found, and there were fewer mineralized areas at the implant's base. Histologically and ultrastructurally, we identified a heterogeneous cellular population including fibroblast-like cells and osteoblasts with abundant amorphous extracellular matrix, as well as a number of inflammatory cells, predominantly neutrophils. In a small area around the implant, microorganisms classified as Actinomyces were identified. In this case, degenerative aspects were predominantly caused by infection. In the second case, our observations focused on recruitment of mesenchymal stem cells, their proliferation and differentiation into epithelial cells with keratinocyte phenotype, and formation of de novo capillaries from mesenchymal progenitors of endothelial cells. These regenerative events were accompanied by multiple areas of mineralization, culminating in bone formation around the implant. Correlative microscopic observations are necessary to conduct in future studies, in various clinical conditions and post-operative stages, to better define the cellular events involved in healing and osseointegration; our observations clearly depict significant regenerative aspects despite the degenerative ones.

Histopathological spectrum of bone lesions associated with dental implant failure: osteomyelitis and beyond

Early or late post-implant placement complications are usually localized infectious/inflammatory processes and treated accordingly. If the healing process does not take place within a reasonable timeframe, the possibility of a pathologic process beyond localized infection/inflammation should be suspected. We describe a radiological/histopathological spectrum of bony lesions ranging from inflammatory to malignant lesions surrounding failed dental implants. Five cases of mandibular dental implant failure that clinically, radiologically and histopathologically appeared to be inflammatory processes are presented. The failure of the dental implants was immediate in two cases and late in the remaining three. The radiological features were essentially similar for all five, and they included radiolucent or mixed radiolucent-radiopaque lesions with poorly defined borders. Three lesions were limited to the area of the failed implant, while the other two extended to a large part of the mandible. The histopathological findings ranged from acute osteomyelitis and chronic osteomyelitis with features of a fibro-osseous-like lesion and occasional rimming of atypical osteoblasts to osteogenic sarcoma that was admixed with a component of osteomyelitis (diagnosis of the latter was achieved only after a series of biopsies). In-depth investigative procedures are imperative in order to establish an accurate diagnosis whenever the histopathological diagnosis is inconsistent with persisting clinical signs and symptoms in bone lesions associated with failed dental implants.

Occlusal overload and bone/implant loss

AIM

The aim of this search was to assess the biological consequences that overload might have on already osseointegrated oral implants through a systematic screening of the scientific literature.

METHOD

Detailed searches through PUBMED, OVID, EMBASE and LILACS databases were made. Articles published up to December 2011 and those reported on the clinical, radiographic and/or histological outcome of oral implants subjected to so-called overload were considered eligible for inclusion. Identified studies were assessed by one non-blinded reviewer according to well-defined inclusion and exclusion criteria. When doubt arose, the co-authors were counselled until final agreement was obtained. The PICO questions formulated was:"what is the effect of overload vs. no overload on bone/implant loss in clinically stable implants?"

RESULTS

The database searches as well as additional hand searching, resulted in 726 potentially relevant titles. Eventually, 16 clinical and 25 animal studies were considered relevant to the topic. After inclusion/exclusion criteria assessment, all clinical studies and all but three animal studies and one systematic review were considered at high risk of bias and excluded. The included animal studies did not reveal an association between overload and peri-implant bone loss in the absence of peri-implant inflammation, whereas in its presence, overload seemed to aggravate the peri-implant tissue breakdown.

CONCLUSIONS

The effect of implant overload on bone/implant loss in clinically well-integrated implants is poorly reported and provides little unbiased evidence to support a cause-and-effect relationship. The PICO question remained unanswered. At the animal level, "overload", mimicked by supra-occlusal contacts acting in an uninflamed peri-implant environment, did not negatively affect osseointegration and even was anabolic. In contrast, supra-occlusal contacts in the presence of inflammation significantly increased the plaque-induced bone resorption.

Bone Grafting Procedures for Osseous Defects Associated with Dental Implants

The purpose of this study was to clinically and radiographically evaluate the use of bone grafting therapy for treatment of osseous defects before implant surgery. After bone graft reconstruction, implants may be placed in previous areas of osseous defect with the expectation of long-term positive results.