Reliability of periodontal diagnostic tools for monitoring peri‐implant health and disease

The prevalence, causes and consequences of crestal bone loss at dental implants are a matter of debate. In recent years, a high prevalence of peri‐implant soft‐tissue inflammation, associated with peri‐implant bone loss, has been reported and the need for treatments similar to those offered for natural teeth affected by periodontitis has been proposed. This suggestion is based on the assumption that periodontal indices, such as probing pocket depth and bleeding on probing, are reliable indicators of the peri‐implant tissue conditions and good predictors of future bone loss. However, based on a critical review of the literature in the present paper, it is concluded that periodontal indices are not reliable either for identifying peri‐implant disease or for predicting future risk for peri‐implant crestal bone loss and implant failure. The long‐term experiences with dental implants, presented in the literature, indicate that the presence of bleeding on probing, probing pocket depths much larger than 4 mm and some bone loss seem to reflect, in most instances, normal conditions of well‐functioning dental implants, bearing in mind that healing of dental implants is the result of a foreign body reaction with the formation of scar tissue. Therefore, the use of probing pocket depth and bleeding on probing assessments may lead to over‐diagnosis and possibly to over‐treatment of assumed biofilm‐mediated peri‐implantitis lesions. It is the opinion of the authors of this review that a treatment should only be initiated when a clinical problem is present based on patient's symptoms (discomfort, pain), the presence of swelling, redness and pus, and significant crestal bone loss over time (as verified with radiographs). The treatment should aim at resolving the infection, which could include removal of the implant.     

Role of epigenetics in alveolar bone resorption and regeneration around periodontal and peri‐implant tissues

Periodontitis and peri‐implantitis are multifactorial diseases characterized by alveolar bone destruction mediated by the host response to a microbial challenge. Alveolar bone resorption mediated by epigenetics could be one of the mechanisms responsible for this destruction of alveolar bone. The relationship between epigenetic modifications and bone metabolism has been thoroughly investigated in bone remodeling, cancer, and rheumatoid arthritis, but evidence is low regarding the relationship between epigenetic modifications and alveolar bone loss related to periodontal and peri‐implant diseases. Therefore, we conducted a review of the pertinent literature based on a priori‐formulated focused questions and a screening strategy, in an attempt to comprehend the role of different epigenetic mechanisms in alveolar bone loss and to determine the current state with respect to their possible therapeutic applications in regenerative medicine. The review showed that the roles of DNA methylation, histone modifications, and non‐coding RNAs in bone loss have been investigated. The results indicate that epigenetic mechanisms can participate in periodontal and peri‐implant alveolar bone breakdown, suggesting their potential as therapeutic targets in alveolar bone regeneration. However, there is still only preliminary information regarding the possible therapeutic utility of these epigenetic mechanisms, suggesting a need for basic and translational research to assess the potential of such mechanisms in promoting alveolar bone regeneration.     

Lasers in minimally invasive periodontal and peri‐implant therapy

Laser therapy has the potential to be an effective, minimally invasive procedure in periodontal therapy. The aim of the present review was to survey the relevant literature on the clinical application of lasers as a minimally invasive treatment for periodontitis and peri‐implant disease. Currently, there are a large number of published clinical studies and case reports that evaluate the adjunctive use of diode, carbon dioxide, neodymium‐doped yttrium aluminium garnet (Nd:YAG), erbium‐doped yttrium aluminium garnet (Er:YAG) and erbium, chromium‐doped: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) lasers or antimicrobial photodynamic therapy for nonsurgical and minimally invasive surgical treatment of periodontal pockets. These procedures are expected not only to control inflammation but also to provide biostimulation effects with photonic energy. Recent meta‐analyses did not show statistically significant differences in pocket reduction and clinical attachment gain compared with mechanical debridement alone, although limited positive effects of adjunctive laser therapy were reported. At present, systematic literature approaches suggest that more evidence‐based studies need to be performed to support the integration of various laser therapies into the treatment of periodontal and peri‐implant diseases. The disparity between previous statistical analyses and individual successful clinical outcomes of laser applications might reveal the necessity of developing optimal laser‐treatment modalities of different wavelengths and better‐defined indications for each protocol.     

Animal models for periodontal regeneration and peri‐implant responses

Translation of experimental data to the clinical setting requires the safety and efficacy of such data to be confirmed in animal systems before application in humans. In dental research, the animal species used is dependent largely on the research question or on the disease model. Periodontal disease and, by analogy, peri‐implant disease, are complex infections that result in a tissue‐degrading inflammatory response. It is impossible to explore the complex pathogenesis of periodontitis or peri‐implantitis using only reductionist in‐vitro methods. Both the disease process and healing of the periodontal and peri‐implant tissues can be studied in animals. Regeneration (after periodontal surgery), in response to various biologic materials with potential for tissue engineering, is a continuous process involving various types of tissue, including epithelia, connective tissues and alveolar bone. The same principles apply to peri‐implant healing. Given the complexity of the biology, animal models are necessary and serve as the standard for successful translation of regenerative materials and dental implants to the clinical setting. Smaller species of animal are more convenient for disease‐associated research, whereas larger animals are more appropriate for studies that target tissue healing as the anatomy of larger animals more closely resembles human dento‐alveolar architecture. This review focuses on the animal models available for the study of regeneration in periodontal research and implantology; the advantages and disadvantages of each animal model; the interpretation of data acquired; and future perspectives of animal research, with a discussion of possible nonanimal alternatives. Power calculations in such studies are crucial in order to use a sample size that is large enough to generate statistically useful data, whilst, at the same time, small enough to prevent the unnecessary use of animals.     

Management of peri‐implant mucositis and peri‐implantitis

Peri‐implant diseases are defined as inflammatory lesions of the surrounding peri‐implant tissues and include peri‐implant mucositis (an inflammatory lesion limited to the surrounding mucosa of an implant) and peri‐implantitis (an inflammatory lesion of the mucosa that affects the supporting bone with resulting loss of osseointegration). This review aims to describe the different approaches to manage both entities and to provide a critical evaluation of the evidence available on their efficacy. Therapy of peri‐implant mucositis and nonsurgical therapy of peri‐implantitis usually involve mechanical debridement of the implant surface using curettes, ultrasonic devices, air‐abrasive devices or lasers, with or without the adjunctive use of local antibiotics or antiseptics. The efficacy of these therapies has been demonstrated for mucositis: controlled clinical trials show an improvement in clinical parameters, especially in bleeding on probing. For peri‐implantitis, the results are limited, especially in terms of probing pocket‐depth reduction. Surgical therapy of peri‐implantitis is indicated when nonsurgical therapy fails to control the inflammatory changes. Selection of the surgical technique should be based on the characteristics of the peri‐implant lesion. In the presence of deep circumferential and intrabony defects, surgical interventions should aim to provide thorough debridement, implant‐surface decontamination and defect reconstruction. In the presence of defects without clear bony walls or with a predominant suprabony component, the aim of the surgical intervention should be the thorough debridement and the repositioning of the marginal mucosa to enable the patient to perform effective oral‐hygiene practices, although this aim may compromise the esthetic result of the implant‐supported restoration.     

Animal models for peri‐implant mucositis and peri‐implantitis

The treatment of infectious diseases affecting osseointegrated implants in function has become a demanding issue in implant dentistry. Since the early 1990s, preclinical data from animal studies have provided important insights into the etiology, pathogenesis and therapy of peri‐implant diseases. Established lesions in animals have shown many features in common with those found in human biopsy material. The current review focuses on animal studies, employing different models to induce peri‐implant mucositis and peri‐implantitis.     

Effects of modified abutment characteristics on peri‐implant soft tissue health: A systematic review and meta‐analysis

Objectives

The purpose of this systematic review was to evaluate the impact of the abutment characteristics on peri‐implant tissue health and to identify the most suitable material and surface characteristics.

Methods

A protocol was developed aimed to answer the following focused question: “Which is the effect of the modification of the abutment design in regard to the maintenance of the peri‐implant soft tissue health?” Further subanalysis aimed to investigate the impact of the abutment material, macroscopic design, surface topography and surface manipulation. Randomised controlled trials (RCTs) with a follow‐up of at least 6 months after implant loading were considered as inclusion criteria. Meta‐analyses were performed whenever possible.

Results

Nineteen final publications from thirteen investigations were included. The results from the meta‐analysis indicated that zirconia abutments (Zi) experienced less increase in BOP values over time [n = 3; WMD = ?26.96; 95% CI (?45.00; ?8.92); p = .003] and less plaque accumulation [n = 1; MD = ?20.00; 95% CI (?41.47; 1.47); p = .068] when compared with titanium abutments (Ti). Bone loss was influenced by the method of abutment decontamination [n = 1; MD = ?0.44; 95% CI (?0.65; ?0.23); p < .001]. The rest of the studied outcomes did not show statistically significant differences.

Conclusions

The macroscopic design, the surface topography and the manipulation of the implant abutment did not have a significant influence on peri‐implant inflammation. In contrast, the abutment material demonstrated increased BOP values over time for Ti when compared to Zi abutments.

     

Clinical approaches to treat peri‐implant mucositis and peri‐implantitis

Therapies proposed for the treatment of peri‐implant diseases are primarily based on the evidence available from treating periodontitis. The primary objective is elimination of the biofilm from the implant surface, and nonsurgical therapy is a commonly used treatment. A number of adjunctive therapies have been introduced to overcome accessibility problems or difficulties with decontamination of implant surfaces as a result of specific surface characteristics. It is now accepted that following successful decontamination, clinicians can attempt to regenerate the bone that was lost as a result of infection. The ultimate goal is re‐osseointegration, and a number of regenerative techniques have been introduced. By reviewing the existing evidence, it seems that peri‐implant mucositis is reversible when appropriately treated. Additionally, a combined therapy (mechanical therapy with local antimicrobials as adjuncts) can serve as an alternative to surgical intervention when treating peri‐implantits in cases not suitable for surgery. Surgical therapy is an effective method for treating peri‐implantitis, and various degrees of success of the use of regenerative procedures have been reported, regardless of whether or not radiographic evidence of defect fill has been achieved. Finally, no matter which therapy is employed, a prerequisite for the long‐term stability of treatment results obtained is the ability of the patient to maintain good oral hygiene.