The evaluation of peri‐implant sulcus fluid osteocalcin,osteopontin, and osteonectin levels in peri‐implant diseases

1 Background

Peri‐implant mucositis is an inflammation of the soft tissues surrounding an implant. Peri‐implantitis refers to a process characterized by peri‐implant bone loss along with an inflammation of the soft tissues. Osteocalcin, osteopontin, and osteonectin proteins are related to bone remodeling. The aim of the present study was to investigate peri‐implant sulcus fluid (PISF) osteocalcin, osteopontin, and osteonectin levels in peri‐implant mucositis and peri‐implantitis.

2 Methods

Fifty‐two implants with peri‐implantitis, 46 implants with peri‐implant mucositis, and 47 control implants were included in the study. Clinical parameters including probing depth, modified sulcus bleeding index and modified plaque index were recorded. PISF osteocalcin, osteopontin, and osteonectin levels were analyzed by ELISA kits.

3 Results

There were no significant differences in PISF osteocalcin, osteopontin, and osteonectin total amounts between healthy controls, peri‐implant mucositis and peri‐implantitis groups (P > 0.05). Probing depths were not correlated with PISF osteocalcin, osteopontin, and osteonectin levels in the study groups (P > 0.05).

4 Conclusions

Soft tissue inflammation around dental implants does not cause a change in osteocalcin, osteopontin, and osteonectin levels in PISF. Also, peri‐implantitis does not seem to give rise to an increase in PISF levels of osteocalcin, osteopontin, and osteonectin.     

Analysis of cathepsin-K activity at tooth and dental implant sites and the potential of this enzyme in reflecting alveolar bone loss

Background: Cathepsin‐K is an enzyme involved in bone metabolism which may make this feature important for both natural teeth and dental implants. The aims of the present study are to comparatively analyze the gingival crevicular fluid (GCF)/peri‐implant sulcus fluid (PISF) cathepsin‐K levels of natural teeth and dental implants, and to assess the potential relationship between this biochemical parameter and alveolar bone loss around natural teeth and dental implants. Methods: Probing depth, bleeding on probing, gingival index, and plaque index clinical parameters were assessed, and GCF/PISF samples were obtained from natural teeth/dental implants presenting with either clinical health, gingivitis/peri‐implant mucositis, or chronic periodontitis/peri‐implantitis. Cathepsin‐K activity levels of 42 GCF samples and 54 PISF samples were determined, and marginal bone loss (MBL) measures were calculated from digitalized standardized intraoral periapical radiographs obtained from natural teeth and dental implants by using cemento‐enamel junction and the actual distance between two consecutive threads of the dental implant as reference points for natural teeth and dental implants, respectively. Results: Comparing the natural teeth group with dental implant group with regard to MBL measure, cathepsin‐K activity, and GCF/PISF volume revealed no significant differences. In both natural teeth and dental implant groups, despite higher MBL measures, cathepsin‐K activity, and GCF/PISF volumes with the presence of inflammation, it was the presence of alveolar bone loss that lead to significantly higher values for these parameters. Conclusion: We suggest cathepsin‐K as a biochemical parameter for monitoring periodontal/peri‐implant alveolar bone loss.     

Evaluation of gingival crevicular fluid and peri‐implant sulcus fluid levels of periostin: A preliminary report

1 Background

Periostin is a protein present in alveolar bone and periodontal ligament whose function is related to response to external forces. The aims of this study are to detect levels of periostin in peri‐implant sulcular fluid (PISF) and gingival crevicular fluid (GCF) and to evaluate the relationship between periostin, pyridinoline cross‐linked carboxyterminal telopeptide of Type I collagen (ICTP), and C‐terminal cross‐linked telopeptide of Type I collagen (CTX) levels and clinical inflammatory symptoms and duration of functional loading.

2 Methods

The study population comprised nine women and four men with mean age 43.23 ± 12.48. Twenty “bone‐level designed” dental implants (DIs) placed in molar or premolar sites, without any signs of peri‐implant bone loss and with a restoration in function for at least 12 months, were included in the study with 20 contralateral natural teeth (NT) as controls. Clinical parameters and restoration dates of the implants were recorded. PISF, GCF, ICTP, CTX, and periostin levels were evaluated using enzyme‐linked immunosorbent assay.

3 Results

ICTP, CTX, and periostin levels were similar between DI and NT groups. There were no statistically significant differences between PISF and GCF values. When implants were grouped as healthy (gingival index [GI] = 0) and inflamed (GI ≥0), ICTP levels and PISF volume were lower in healthy implants compared with the inflamed group. Both periostin and CTX levels were negatively correlated with functioning time, suggesting less bone remodeling around DIs at later stages of functioning.

4 Conclusion

Findings of this study suggest collagen breakdown products may be used as markers to evaluate peri‐implant metabolism.     

Tenascin-C and matrix metalloproteinase-9 levels in crevicular fluid of teeth and implants

Background: The role of and interaction between bacterial infection and biomechanical impact in the development of peri‐implant inflammatory processes is not clear. Objective: To determine the amount and concentration of tenascin‐C (TNC) in gingival crevicular fluid (GCF) around teeth and in peri‐implant sulcus fluid from healthy implants and implants with peri‐implantitis, and to correlate it with matrix metalloproteinase‐9 (MMP‐9) levels. Materials and Methods: Seven control individuals and 18 patients with 41 implants with/without peri‐implantitis were included. GCF was collected with filter strips and volumes were measured with a Periotron device. The amount of serum albumin per sample was quantified by densitometric analysis of Coomassie‐stained sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Relative activity of MMP‐9 was determined from the densitometry of zymograms. Amounts and concentrations of TNC were evaluated by ELISA. Results: Relative MMP‐9 activity was increased in peri‐implantitis. A tendency was observed to measure higher TNC concentrations at teeth than at implants. The amount of TNC in GCF collected from healthy implant sites and the peri‐implantitis sites was significantly different. Based on immunoblotting, TNC in GCF seemed degraded. In contrast to TNC, MMP‐9 was significantly related to the PD and the volume of GCF. Conclusion: TNC is known to be induced in inflammation. The increase found in peri‐implantitis was less than expected. In the context of peri‐implantitis, TNC might be a marker of bone remodelling rather than inflammation and infection. A possible proteolytic degradation of TNC during peri‐implantitis needs to be studied.     

Prevalence and Predictive Factors for Peri‐Implant Disease and Implant Failure: A Cross‐Sectional Analysis

Background: Long‐term studies worldwide indicate that peri‐implant inflammation is a frequent finding and that the prevalence of peri‐implantitis correlates with loading time. Implant loss, although less frequent, has serious oral health and economic consequences. An understanding of predictive factors for peri‐implant disease and implant loss would help providers and patients make informed decisions. Methods: A cross‐sectional study was performed on 96 patients with 225 implants that were placed between 1998 and 2003. Implant placement data were collected from patient records, and patients presented for a clinical and radiographic follow‐up examination. Implant status and periodontal status were determined, the data were analyzed to determine the prevalence of peri‐implant disease or implant loss, and a predictive model was tested. Results: The mean follow‐up time for the patients was 10.9 years. The implant survival rate was 91.6%. Peri‐implant mucositis was found in 33% of the implants and 48% of the patients, and peri‐implantitis occurred in 16% of the implants and 26% of the patients. Individuals with peri‐implantitis were twice as likely to report a problem with an implant as individuals with healthy implants. Peri‐implantitis is associated with younger ages and diabetes at the time of placement and with periodontal status at the time of follow‐up. Implant loss is associated with diabetes, immediate placement, and larger‐diameter implants. Conclusions: One in four patients and one in six implants have peri‐implantitis after 11 years. The data suggest that periodontal and diabetes status of the patient may be useful for predicting implant outcomes.     

Surgical treatment of peri‐implantitis: Prognostic indicators of short‐term results

Aim

To evaluate the clinical and radiographic short‐term (6 months) effect of surgical treatment of peri‐implantitis, and to identify prognostic indicators affecting the outcome using a multilevel statistical model.

Materials & Methods

A total of 143 implants (45 patients) with a diagnosis of progressive peri‐implantitis (progressive bone loss (PBL) ≥2.0 mm and bleeding on probing (BoP)/suppuration) received surgical treatment. Clinical and radiographic parameters were assessed 6 months postoperatively. Potential prognostic indicators on subject, implant and site level prior to surgery were analysed to evaluate the effect on individual and composite outcomes using multilevel logistic regression analysis.

Results

At the 6‐month evaluation, none of the implants demonstrated PBL and 14% of the implants were registered with the absence of bleeding and no pocket probing depth ≥6 mm. Multilevel regression analysis identified, among others, suppuration, pocket probing depth >8 mm, bone loss >7 mm and the presence of plaque as criteria associated with the outcome.

Conclusion

Resective peri‐implantitis surgery seemed to reduce the amount of peri‐implant inflammation. However, most of the sites continued to have BoP/suppuration. Thus, long‐term maintenance and evaluation is warranted. The effect of treatment was reduced by some prognostic indicators such as the presence of suppuration prior to interception and peri‐implant bone loss exceeding 7 mm.     

Composition of supra- and subgingival biofilm of subjects with healthy and diseased implants

Objectives: The purpose of this study was to compare the microbial composition of supra‐ and subgingival biofilm in subjects with and without peri‐implantitis. Material and methods: Forty‐four subjects (mean age 48.9 ± 13.51 years) with at least one implant restored and functional for at least 2 years were assigned to two groups: a peri‐implantitis group (n=22), consisting of subjects presenting peri‐implant sites with radiographic defects >3 mm, bleeding on probing and/or suppuration; and a control group (n=22), consisting of subjects with healthy implants. The clinical parameters evaluated were plaque index, gingival bleeding, bleeding on probing, suppuration, probing depth and clinical attachment level. Supra‐ and subgingival biofilm samples were taken from the deepest sites of each implant and analyzed for the presence of 36 microorganisms by checkerboard DNA–DNA hybridization. Results: Higher mean counts of Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia were observed in the peri‐implantitis group, both supra‐ and subgingivally (P<0.05). The proportions of the pathogens from the red complex were elevated, while host‐compatible beneficial microbial complexes were reduced in diseased compared with healthy implants. The microbiological profiles of supra‐ and subgingival environments did not differ substantially within each group. Conclusion: Marked differences were observed in the composition of supra‐ and subgingival biofilm between healthy and diseased implants. The microbiota associated with peri‐implantitis was comprised of more periodontal pathogenic bacterial species, including the supragingival biofilm.     

Increased Levels of Dissolved Titanium Are Associated With Peri‐Implantitis – A Cross‐Sectional Study

Background: Peri‐implantitis represents a disruption of the biocompatible interface between the titanium dioxide layer of the implant surface and the peri‐implant tissues. Increasing preclinical data suggest that peri‐implantitis microbiota not only triggers an inflammatory immune response but also causes electrochemical alterations of the titanium surfaces, i.e., corrosion, that aggravate this inflammatory response. Thus, it was hypothesized that there is an association between dissolution of titanium from dental implants, which suggests corrosion, and peri‐implantitis in humans. The objective of this study is to compare levels of dissolved titanium in submucosal plaque collected from healthy implants and implants with peri‐implantitis. Methods: Submucosal plaque from 20 implants with peri‐implantitis and 20 healthy implants was collected with sterile curets from 30 participants. Levels of titanium were quantified using inductively coupled plasma mass spectrometry and normalized for mass of bacterial DNA per sample to exclude confounding by varying amounts of plaque per site. Statistical analysis was performed using generalized estimated equations to adjust for clustering of implants per participant. Results: Implants with peri‐implantitis harbored significantly higher mean levels of titanium (0.85 ± 2.47) versus healthy implants (0.07 ± 0.19) after adjusting for amount of plaque collected per site (P = 0.033). Conclusions: Greater levels of dissolved titanium were detected in submucosal plaque around implants with peri‐implantitis compared with healthy implants, indicating an association between titanium dissolution and peri‐implantitis. Factors triggering titanium dissolution, as well as the role of titanium corrosion in the peri‐implant inflammatory process, warrant further investigation.     

Myeloperoxidase as a measure of polymorphonuclear leukocyte response in inflammatory status around immediately and delayed loaded dental implants: a randomized controlled clinical trial

Background: As well as gingival crevicular fluid (GCF), peri‐implant sulcus fluid (PISF) may have a potential diagnostic value for the early identification of metabolic and destructive processes. Purpose: The aim of this study was to analyze the potential impact of inflammation and loading on PISF myeloperoxidase (MPO) levels, in comparison with GCF. Materials and Methods: A total of 220 sites, dental implant (immediately [IL] or delayed loaded [DL]), and natural tooth, either healthy/noninflamed or gingivitis/inflamed, were classified. Clinical parameters were recorded, and GCF/PISF samples were obtained. GCF/PISF MPO levels were spectrophotometrically determined. Results: Clinical parameters demonstrated increases with the presence of gingival/peri‐implant inflammation. Total MPO levels were higher at inflamed tooth and implant sites compared to noninflamed/healthy sites (p < .05). Although they did not reach a significance level, inflamed IL sites had higher total MPO levels than inflamed DL sites (p = .401). Gingival index and total MPO levels exhibited significant correlations (p < .05). Conclusion: Using implants and natural teeth in the same study design, the findings of the present study support the close relationship between MPO production and inflammation, and may speculate a potential for loading of dental implants, contributing to the MPO content of PISF.     

Diagnostic accuracy of clinical parameters to monitor peri‐implant conditions: A matched case‐control study

1 Background

The aim of this case‐control study was to estimate the diagnostic accuracy of the standard clinical parameters in diagnosing healthy peri‐implant tissues, peri‐implant mucositis, and peri‐implantitis.

2 Methods

A case‐control study was designed to compare the clinical parameters used in the diagnosis of peri‐implant diseases such as: probingdepth (PD), bleeding on probing (BOP), mucosal redness (MR), suppuration (SUP), and plaque index (PI). Furthermore, the influence of patient‐ (sex, age) and implant‐related variables (implant neck configuration, time in function after loading) were evaluated to investigate the association with the clinical findings. The inferential analysis consisted of estimation by generalized estimating equations (GEE) of multilevel logistic regression models.

3 Results

In total, 1,572 sites were evaluated around 262 implants from 141 patients. Sites with implant mucositis showed significant levels of BOP (OR = 3.56), MR (OR = 7.66) and PD (OR = 1.48) compared to healthy sites. The specificity was 90.3% while the sensitivity was only 43.6%. Likewise, sites exhibiting peri‐implantitis showed significant levels of BOP (OR = 2.32), MR (OR = 7.21), PD (OR = 2.43) and SUP (OR = 6.81) compared to healthy sites. Again, the multiple logistic regressions showed high specificity (92.1%) but modest sensitivity (52.5%). PD was the only diagnostic marker displaying significance comparing peri‐implant mucositis and peri‐implantitis sites (OR = 1.76). Moreover, tissue‐level compared to bone‐level implants were less associated with SUP+ (OR = 0.20), and PI (OR = 0.36) and demonstrated statistical significance. In addition, age, sex, and function time significantly influenced the tested clinical parameters.

4 Conclusions

The diagnosis of peri‐implant diseases cannot rely solely upon individual clinical parameters but rather require a combination of criteria. The clinical parameters, particularly probing depth, might accurately discern between diagnoses among peri‐implant conditions. Nevertheless, the specificity of the clinical parameters surpasses the sensitivity in the detection of peri‐implant diseases, validating its potential use as a diagnostic tool.     

The Peri‐Implant Sulcus Compared with Internal Implant and Suprastructure Components: A Microbiological Analysis

Purpose: A recent in vivo study has shown considerable contamination of internal implant and suprastructure components with great biodiversity, indicating bacterial leakage along the implant‐abutment interface, abutment‐prosthesis interface, and restorative margins. The goal of the present study was to compare microbiologically the peri‐implant sulcus to these internal components on implants with no clinical signs of peri‐implantitis and in function for many years. Checkerboard DNA‐DNA hybridization was used to identify and quantify 40 species. Material and Methods: Fifty‐eight turned titanium Brånemark implants in eight systemically healthy patients (seven women, one man) under regular supportive care were examined. All implants had been placed in the maxilla and loaded with a screw‐retained full‐arch bridge for an average of 9.6 years. Gingival fluid samples were collected from the deepest sulcus per implant for microbiological analysis. As all fixed restorations were removed, the cotton pellet enclosed in the intra‐coronal compartment and the abutment screw were retrieved and microbiologically evaluated. Results: The pellet enclosed in the suprastructure was very similar to the peri‐implant sulcus in terms of bacterial detection frequencies and levels for practically all the species included in the panel. Yet, there was virtually no microbial link between these compartments. When comparing the abutment screw to the peri‐implant sulcus, the majority of the species were less frequently found, and in lower numbers at the former. However, a relevant link in counts for a lot of bacteria was described between these compartments. Even though all implants in the present study showed no clinical signs of peri‐implantitis, the high prevalence of numerous species associated with pathology was striking. Conclusions: Intra‐coronal compartments of screw‐retained fixed restorations were heavily contaminated. The restorative margin may have been the principal pathway for bacterial leakage. Contamination of abutment screws most likely occurred from the peri‐implant sulcus via the implant‐abutment interface and abutment‐prosthesis interface.     

Treatment Outcome in Patients With Peri‐Implantitis in a Periodontal Clinic: A Retrospective Study

Background: The number of placed implants has grown during the past decade, and the prevalence of peri‐implantitis has increased. The purpose of the present study is to investigate the treatment outcome of peri‐implantitis and to identify factors influencing the treatment success rate. Methods: The study was conducted as a retrospective longitudinal study on a referral population. The material included 382 implants with peri‐implantitis in 150 patients. Peri‐implantitis was defined as presence of pocket depths ≥5 mm, bleeding at probing and/or suppuration, and the presence of implant radiographic bone loss ≥3 mm or bone loss comprising at least three threads of the implant. Variance analyses, χ² analyses, and logistic regression analysis were used for data analyses. Results: The mean age of the participants at baseline was found to be 64 years (range: 22 to 87 years). The mean ± SD follow‐up time was 26 ± 20 months, and the mean time between implant installation and baseline was 6.4 years (range: 1 to 20 years). Periodontal flap surgery with osteoplasty was the most common type of therapy (47%), and regenerative surgery procedures with bone substitute materials were chosen in 20% of the cases. The mean success rate at patient level was 69%. The results of the logistic regression analyses showed that the success rate was significantly lower for individuals with the diagnosis of severe periodontitis, severe marginal bone loss around the implants, poor oral hygiene, and low compliance. Conclusion: The effectiveness of the peri‐implantitis therapy was impaired by severe periodontitis, severe marginal bone loss around the implants, poor oral hygiene, and low compliance.     

Outcome of surgical treatment of peri-implantitis: results from a 2-year prospective clinical study in humans

Aim: The aim of the present study was to evaluate the outcome of a surgical procedure based on pocket elimination and bone re‐contouring for the treatment of peri‐implantitis. Material and methods: The 31 subjects involved in this study presented clinical signs of peri‐implantitis at one or more dental implants (i.e. ≥6 mm pockets, bleeding on probing and/or suppuration and radiographic evidence of ≥2 mm bone loss). The patients were treated with a surgical procedure based on pocket elimination and bone re‐contouring and plaque control before and following the surgery. At the time of surgery, the amount of bone loss at implants was recorded. Results: Two years following treatment, 15 (48%) subjects had no signs of peri‐implant disease; 24 patients (77%) had no implants with a probing pocket depth of ≥6 mm associated with bleeding and/or suppuration following probing. A total of 36 implants (42%) out of the 86 with initial diagnosis of peri‐implantitis presented peri‐implant disease despite treatment. The proportion of implants that became healthy following treatment was higher for those with minor initial bone loss (2–4 mm bone loss as assessed during surgery) compared with the implants with a bone loss of ≥5 mm (74% vs. 40%). Among the 18 implants with bone loss of ≥7 mm, seven were extracted. Between the 6‐month and the 2‐year examination, healthy implants following treatment tended to remain stable, while deepening of pockets was observed for those implants with residual pockets. Conclusion: The results of this study indicated that a surgical procedure based on pocket elimination and bone re‐contouring and plaque control before and following surgery was an effective therapy for treatment of peri‐implantitis for the majority of subjects and implants. However, complete disease resolution at the site level seems to depend on the initial bone loss at implants. Implants with no signs of peri‐implantitis following treatment tended to remain healthy during the 2‐year period, while a tendency for disease progression was observed for the implants that still showed signs of peri‐implant disease following treatment. To cite this article:
Serino G, Turri A. Outcome of surgical treatment of peri‐implantitis: results from a 2‐year prospective clinical study in humans.
Clin. Oral Impl. Res. 22 , 2011; 1214–1220.
doi: 10.1111/j.1600‐0501.2010.02098.x     

Radiographic evaluation of modern oral implants with emphasis on crestal bone level and relevance to peri‐implant health

Implant stability and maintenance of stable crestal bone level are prerequisites for the successful long‐term function of oral implants, and continuous crestal bone loss constitutes a threat to the longevity of implant–supported prosthetic constructions. The prevalence/incidence and reasons for crestal bone loss are under debate. Some authors regard infection (i.e. peri‐implantitis) as the cause for virtually all bone loss, while others see crestal bone loss as an unavoidable phenomenon following surgery and implant loading. Irrespective of the cause of continuous crestal bone loss, correct usage and scientifically sound interpretation of radiographs are of utmost importance for evaluation of oral implants. The periapical radiographic technique is currently the preferred method for evaluating implant health based on bone loss, and digital radiographs allow easy standardization of the image contrast. It is suggested that baseline radiographs should be taken at the time the transmucosal part pierces the mucosal tissues and annually thereafter. The number of unreadable radiographs should be presented in scientific publications to give insights into the quality of the radiographic examination. It is suggested that not only mean values, but also the range of bone levels, should be presented to describe the proportion of implants that show continuous crestal bone loss. In the absence of other clinical symptoms, bleeding on probing around implants seems to be a weak indicator of ongoing or future loss of crestal bone. According to recent longitudinal studies on modern implant surfaces peri‐implantitis defined as ‘infection with suppuration associated with clinically significant progressing crestal bone loss’ occurs with a prevalence of less than 5 % in implants with 10 years in function.     

Correlation between different genotypes of human cytomegalovirus and Epstein-Barr virus and peri-implant tissue status

Background: The purpose of this study was to estimate the prevalence of different genotypes of human cytomegalovirus (HCMV) and Epstein‐Barr virus (EBV) in peri‐implantitis and mucositis sites, and to evaluate the correlation between herpesvirus presence and clinical parameters. Methods: A total of 80 dental implants (mean time of loading, 4.16 ± 1.8 years) were evaluated during the course of the study (30 peri‐implantitis, 25 mucositis and 25 healthy peri‐implant sites). The following clinical parameters were assessed: visible plaque index, bleeding on probing, suppuration and probing depth. A polymerase chain reaction (PCR) assay was used to identify the presence of different HCMV and EBV genotypes in peri‐implant tissue plaque samples. Results: HCMV‐2 was detected in 53.3% and EBV‐1 in 46.6% of the 30 peri‐implantitis sites evaluated. By contrast, HCMV‐2 was not detected in healthy periodontal sites and EBV‐1 was detected in one healthy site. A statistically significant correlation was found between the presence of HCMV‐2 and EBV‐1 genotypes and clinical parameters of peri‐implantitis. Conclusions: The results from the present study confirmed the high prevalence of HCMV‐2 and EBV‐1 in the peri‐implant tissue plaque of peri‐implantitis sites and suggests a possible active pathogenic role of the viruses in peri‐implantitis.     

A Cross‐Sectional Assessment of Biomarker Levels Around Implants Versus Natural Teeth in Periodontal Maintenance Patients

Background: Recent studies point to the clinical utility of using peri‐implant sulcular fluid (PISF) as a valuable diagnostic aid for monitoring peri‐implant tissue health. The objectives of this study are to determine the levels of key biomarkers in PISF in periodontal maintenance participants and compare them with their corresponding levels in gingival crevicular fluid (GCF) obtained from the same participants. Methods: PISF and GCF were collected from an implant and a contralateral natural tooth after the clinical examination of 73 participants. The levels of interleukin (IL)‐1α, IL‐1β, IL‐6, IL‐8, IL‐10, IL‐12, IL‐17A, tumor necrosis factor (TNF)‐α, C‐reactive protein, osteoprotegerin, leptin, and adiponectin were determined using multiplex proteomic immunoassays. The correlation of biomarker concentrations between GCF versus PISF, within GCF or PISF, and with several covariates (age, brushing frequency, days since professional cleaning, probing depth [PD], and plaque index) were also determined. Results: Significantly higher levels of IL‐17A (P = 0.02) and TNF‐α (P = 0.03) were noted in PISF when compared with their levels in GCF. Significant positive correlations were noted between the concentrations of cytokines in PISF versus their levels in GCF. Among the covariates, a significant positive correlation was noted between mean PDs around implants and levels of IL‐1β (P <0.05) and IL‐8 (P <0.05) in PISF. Conclusion: The results of this study point to the differential expression of specific biomarkers in GCF versus their levels in PISF in periodontal maintenance patients, which is critical information before establishing PISF as a diagnostic fluid to monitor peri‐implant health.     

A Novel Rat Model of Polymicrobial Peri‐Implantitis: A Preliminary Study

Background: Peri‐implantitis is a complex polymicrobial biofilm‐induced inflammatory osteolytic gingival infection that results in orofacial implant failures. To the best knowledge of the authors, there are no preclinical in vivo studies in implant dentistry that have investigated the inflammatory response to known microbial biofilms observed in humans. The aim of this study is to develop a novel peri‐implant rat model using an established model of polymicrobial periodontitis. Methods: Wistar rats were used for the study of experimental peri‐implantitis. One month after extraction of maxillary first molars, a titanium mini‐implant was inserted. Two months after implant healing, implants were uncovered, and abutment fixing was done using cyanoacrylate to prevent abutment loosening. Rats were separated into two groups (group A: polymicrobial‐infected and group B: sham‐infected). One week after healing of abutments, rats were infected with Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia for 12 weeks. Bacterial colonization, bone resorption, and implant inflammation were evaluated by polymerase chain reaction (PCR), microcomputed tomography, and histology, respectively. Results: Three rats with four implants in the infection group and two rats with three implants in the sham‐infection group were analyzed. PCR analysis revealed presence of bacterial genomic DNA, and infection elicited significant immunoglobulin (Ig)G and IgM antibody responses, indicating bacterial colonization/infection around implants. Infection induced an enhanced mean distance from implant platform to the first bone‐to‐implant contact, extensive peri‐implantitis with advanced bone resorption, and extensive inflammation with granulation tissue and polymorphonuclear leukocytes. Conclusions: To the best knowledge of the authors, this is the first study to develop a novel rat model of polymicrobial peri‐implantitis. With modifications to improve implant retention it could offer significant advantages for studies of initiation and progression of peri‐implantitis.     

Molecular tools for preventing and improving diagnosis of peri‐implant diseases

Peri‐implantitis is an inflammatory disease of tissues surrounding osseointegrated dental implants. Inflammation affecting soft and hard peri‐implant tissues can cause alveolar bone resorption and subsequent implant loss. Clinical surveillance and early diagnosis are of paramount importance to reduce clinical failures and improve implant survival. Current diagnosis of implants is based on clinical and radiological signs. Molecular tests are an emerging diagnostic methodology, which potentially can help to detect and prevent early peri‐implantitis and monitor the efficacy of therapy as well. A plethora of potential biomarkers are potentially available to support the clinical diagnosis of peri‐implantitis. However, conflicting diagnostic conclusions have been reached, probably related to weak statistical results due to limited sample size or disease heterogeneity. The present paper reviews candidate diagnostic biomarkers for peri‐implantitis, including infective agents, genetic susceptibility factors, and key proteins related to inflammation and tissue remodeling.     

Long‐Term Effect of Surface Roughness and Patients' Factors on Crestal Bone Loss at Dental Implants. A Systematic Review and Meta‐Analysis

Publications from 2011 to 2015 were selected to evaluate effect of implant surface roughness on long‐term bone loss as surrogate for peri‐implantitis risk. 87 out of 2,566 papers reported the mean bone loss after at least 5 years of function. Estimation of the proportion of implants with bone loss above 1, 2, and 3 mm as well as analysis the effect of implant surface roughness, smoking, and history of periodontitis was performed. By means of the provided statistical information of bone loss (mean and standard deviation) the prevalence of implants with bone loss ranging from 1 to 3 mm was estimated. The bone loss was used as a surrogate parameter for “peri‐implantitis” given the fact that “peri‐implantitis” prevalence was not reported in most studies or when reported, the diagnostic criteria were unclear or of dubious quality. The outcome of this review suggests that peri‐implant bone loss around minimally rough implant systems was statistically significant less in comparison to the moderately rough and rough implant systems. No statistically significant difference was observed between moderately rough and rough implant systems. The studies that compared implants with comparable design and different surface roughness, showed less average peri‐implant bone loss around the less rough surfaces in the meta‐analysis. However, due to the heterogeneity of the papers and the multifactorial cause for bone loss, the impact of surface roughness alone seems rather limited and of minimal clinical importance. Irrespective of surface topography or implant brand, the average weighted implant survival rate was 97.3% after 5 years or more of loading. If considering 3 mm bone loss after at least 5 years to represent the presence of “peri‐implantitis,” less than 5% of the implants were affected. The meta‐analysis indicated that periodontal history and smoking habits yielded more bone loss.     

Estimation of Bone Loss Biomarkers as a Diagnostic Tool for Peri‐Implantitis

Background: The aims of this study are to estimate the profile of bone loss biomarkers in peri‐implant tissues and to identify potential prognostic biomarkers of peri‐implantitis. Methods: Peri‐implant crevicular fluid samples collected from 164 participants (52 patients with peri‐implantitis, 54 with mucositis, and 58 with healthy peri‐implant tissues) were analyzed using enzyme‐linked immunosorbent assays to evaluate concentrations of the receptor activator of nuclear factor‐κB (RANK), soluble RANK ligand (sRANKL), osteoprotegerin (OPG), cathepsin‐K, and sclerostin. Results: Concentrations of RANK, sRANKL, OPG, and sclerostin were significantly increased in patients with peri‐implantitis compared with patients with healthy peri‐implant tissues. Comparisons between peri‐implantitis and mucositis demonstrated significantly higher values of sclerostin in peri‐implantitis samples. Comparisons between mucositis and healthy peri‐implant tissues showed significantly increased levels of RANK and cathepsin‐K in mucositis. Conclusion: These results are suggestive of a role of sRANKL, OPG, and sclerostin as prognostic biomarkers in peri‐implantitis.