Reversibility of experimental peri-implant mucositis compared with experimental gingivitis in humans

Objective: To monitor clinical, microbiological and host‐derived alterations occurring around teeth and titanium implants during the development of experimental gingivitis/mucositis and their respective healing sequence in humans. Material and methods: Fifteen subjects with healthy or treated periodontal conditions and restored with dental implants underwent an experimental 3‐week period of undisturbed plaque accumulation in the mandible. Subsequently, a 3‐week period with optimal plaque control was instituted. At Days 0, 7, 14, 21, 28, 35 and 42, the presence/absence of plaque deposits around teeth and implants was assessed, (plaque index [PlI]) and the gingival/mucosal conditions were evaluated (gingival index[GI]). Subgingival/submucosal plaque samples and gingival/mucosal crevicular fluid (CF) samples were collected from two pre‐determined sites around each experimental unit. CF samples were analyzed for matrix‐metalloproteinase‐8 (MMP‐8) and interleukin‐1beta (IL‐1β). Microbial samples were analyzed using DNA–DNA hybridization for 40 species. Results: During 3 weeks of plaque accumulation, the median PlI and GI increased significantly at implants and teeth. Implant sites yielded a greater increase in the median GI compared with tooth sites. Over the 6‐week experimental period, the CF levels of MMP‐8 were statistically significantly higher at implants compared with teeth (P<0.05). The CF IL‐1β levels did not differ statistically significantly between teeth and implants (P>0.05). No differences in the total DNA counts between implant and tooth sites were found at any time points. No differences in the detection frequency were found for putative periodontal pathogens between implant and tooth sites. Conclusion: Peri‐implant soft tissues developed a stronger inflammatory response to experimental plaque accumulation when compared with that of their gingival counterparts. Experimental gingivitis and peri‐implant mucositis were reversible at the biomarker level. Clinically, however, 3 weeks of resumed plaque control did not yield pre‐experimental levels of gingival and peri‐implant mucosal health indicating that longer healing periods are needed. To cite this article:
Salvi GE, Aglietta M, Eick S, Sculean A, Lang NP & Ramseier CA. Reversibility of experimental peri‐implant mucositis compared with experimental gingivitis in humans.
Clin. Oral Impl. Res. 23 , 2012; 182–190.
doi: 10.1111/j.1600‐0501.2011.02220.x     

Peri‐implant parameters in head and neck reconstruction: influence of extraoral skin or intraoral mucosa

Objective: This study is designed to assess dental implants supporting overdentures in edentulous patients with operated head and neck malignancies using parameters to detect peri‐implant disease. Material and methods: Thirty‐four implants supporting overdentures in 34 oral cancer patients were examined. Clinical parameters [plaque index, probing depth, bleeding on probing (BOP), origin of peri‐implant soft tissue, and amount of irradiation] were recorded, and microbiological identification of periodontal pathogens was carried out by DNA–DNA hybridization. To identify yeast species, the samples were cultivated on Sabouraud agar plates and subsequently identified by API 20C AUX plates. An implant site showing BOP, probing pocket depth (PPD)≥5 mm and radiographic vertical bone loss was considered to have peri‐implant disease. Results: Colonization by periodontal pathogens was found on 15 implants, while yeast species were found in 14 cases. Using a univariate analysis, none of the investigated parameters (microbiologic sign, detection of yeast, origin of peri‐implant soft tissue and irradiation) were significantly correlated to signs of peri‐implant disease. In the multivariate analysis, yeast [odds ratio (OR) 12.32, P=0.033] and periodontal pathogen (OR 9.88, P=0.046) were significant predictor variables for peri‐implant disease. Yeasts were less frequently detected around implants placed in re‐vascularized skin flaps if irradiation was set as a confounder (P=0.019). Conclusions: With respect to the pilot study nature of the study peri‐implant soft tissue origin and irradiation had little influence on the development of peri‐implant disease. Yeast and periodontal pathogen were explanatory variables for the development of peri‐implant disease. Considering the effect of irradiation on the prevalence of yeast, yeast was less frequently observed in peri‐implant soft tissue of the skin. Based on these data, future studies on the role of yeast and soft tissue in peri‐implant disease should be encouraged. To cite this article:
Kwon Y‐D, Karbach J, Wagner W, Al‐Nawas B. Peri‐implant parameters in head and neck reconstruction: influence of extraoral skin or intraoral mucosa.
Clin. Oral Impl. Res. 21 , 2010; 316–320.
doi: 10.1111/j.1600‐0501.2009.01763.x     

Clinical follow-up of unilateral, fixed dental prosthesis on maxillary implants

Aims/Background: The aims of the present study were to evaluate (1) the success rate of unilateral maxillary fixed dental prosthesis (FDPs) on implants in patients at a periodontal clinic referred for periodontal treatment, (2) the prevalence of varying mechanical and biological complications and (3) effects of potential risk factors on the success rate. Material and methods: Fifty consecutive patients were invited to participate in a follow‐up. The patients had received FDPs on implants between November 2000 and December 2003 after treatment to achieve optimal peridontal health, and the FDPs had been in function for at least 3 years. A questionnaire was sent to the patients before the follow‐up examination. Forty‐six patients with 116 implants were examined. The follow‐up comprised clinical and radiographic examinations and evaluations of treatment outcome. Results: Before implant treatment, 13% of the teeth were extracted; of these, 80% were extracted due to periodontal disease. No implants had been lost before implant loading. One implant in one patient fractured after 3 years of functional loading and three implants in another patient after 6.5 years. The most frequent mechanical complications were veneer fractures and loose bridge screws. Patients with peri‐implant mucositis had significantly more bleeding on probing around teeth and implants. Patients with peri‐implantitis at the follow‐up had more deep periodontal pockets around their remaining teeth compared with individuals without peri‐implantitis, but these differences were not significant. Smokers had significantly fewer teeth, more periodontal pockets ≥4 mm and a tendency towards greater marginal bone loss at the follow‐up, compared with non‐smokers. Conclusion: In the short term, overloading and bruxism seem more hazardous for implant treatment, compared with a history of periodontitis. To cite this article:
Wahlström M, Sagulin G‐B, Jansson LE. Clinical follow‐up of unilateral, fixed dental prosthesis on maxillary implants
Clin. Oral Impl. Res. 21 , 2010; 1294–1300.
doi: 10.1111/j.1600‐0501.2010.01948.x     

Microbiologic diagnostics at titanium implants

Background: The microbiota found at periimplant lesions have been shown to contain putative periodontal pathogens as well as opportunistic species such as Staphylococcus spp, enterics, and Candida spp. Therefore, a microbiologic diagnosis may be of value as guidance before treatment of such lesions. Purpose: The aim of this study was to evaluate the prevalence of some putative pathogens associated with long‐term fol‐lowed‐up cases using two different microbiologic procedures. Malerials and Methods: Fifteen subjects contributed with plaque samples from teeth and implants; these were analyzed with respect to 18 putative periimplant pathogens using cultural methods and a deoxyribonucleic acid DNA‐DNA hybridization technique. Results: The number of individuals positive for the analyzed pathogens was similar in samples taken from teeth and implants when analyzed with the DNA‐DNA hybridization technique. When comparing detection frequency by culture procedure and by “checkerboard” technique at implants, the number of individuals positive for these species was lower with the traditional culture technique than with the checkerboard analyses. Using a higher cutoff point (4) with the checkerboard technique, the number of positive individuals was generally lower than that found with the culture technique. When comparing the techniques on an implant site level, the prevalence obtained by culture was lower for all analyzed species. If the specific species were present in the samples analyzed by the checkerboard technique, they were present only in every second sample analyzed with the culture technique. The high specificity values showed that if the checkerboard technique did not detect any Porphyromonas gingivalis, Prevotla intermedia, Actinobadllus actinomycetem‐comitans, or Fusobacterium nudeatum, the bacteria were also undetectable by the culture technique. The two methods therefore did not overlap but did supplement each other. Conclusions: Based on the current results it is recommended that the technique used when analyzing microbiota around titanium implants should be a combination of the two protocols mentioned as they seem to give the most comprehensive outcome when used together.     

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.     

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.     

Peri-implant bone alterations in relation to inter-unit distances. A 3-year retrospective study

Abstract: The aim of the present retrospective study was to evaluate longitudinal alterations in radiographic bone topography at proximal sites of three‐unit implant‐supported fixed partial prostheses during the first 3 years after bridge installation, in relation to vertical and horizontal inter‐unit distances. The subjects were partially dentate patients who had received implant‐supported fixed partial prostheses during the year 1995 at the Brånemark Clinic, Göteborg, Sweden. For inclusion in the study, the patient had to have a three‐unit bridge construction supported by three implants in the posterior area of the jaw. Twenty‐eight patients having 35 screw‐retained prostheses on Brånemark standard implants fulfilled the inclusion criteria. Radiographs obtained at bridge installation and at 1‐ and 3‐year follow‐ups were assessed for implant positions, contact point level, bone level at implants and adjacent tooth and mid‐proximal bone crest level. The data were analysed with respect to two proximal units: tooth/implant units (n=35) and implant/implant units (n=70). Multiple regression analyses were used to evaluate the influence of various factors on the peri‐implant and periodontal bone level changes during the 3 years of follow‐up. At the tooth/implant units, the mean bone loss over the 3 years was 0.5 mm at the implant and 0.4 mm at the tooth. Multiple regression analysis failed to identify significant explanatory factors for the peri‐implant/periodontal bone level changes at the tooth/implant units (R²=0.28). At the implant/implant units, the peri‐implant bone loss was 0.6–0.7 mm and was significantly influenced by the vertical inter‐implant distance (P<0.01), the difference in bone level at baseline between two neighbouring implants (P<0.001) and the bone level changes at the opposed implant surface (P<0.001) (R²=0.49). Furthermore, the magnitude of apical displacement of the inter‐implant bone crest level during the 3 years of follow‐up was negatively associated with the horizontal inter‐implant distance (P<0.05). The results of the study demonstrated that both vertical and horizontal differences in implant positions might influence bone alterations in the inter‐implant area during the first 3 years of loading, while the data failed to show corresponding relationships for the bone changes at the proximal area between the implant and the neighbouring tooth.     

IL-1RN gene polymorphism is associated with peri-implantitis

Objectives: Interleukin (IL)‐1α, IL‐1β and their natural specific inhibitor IL‐1 receptor antagonist (IL‐1ra) play a key role in the regulation of the inflammatory response in periodontal tissues. Polymorphisms in the IL‐1 gene cluster have been associated with severe adult periodontitis. We aimed to investigate the IL‐1 gene cluster polymorphisms in patients with peri‐implantitis. Material and methods: The study included 120 North Caucasian individuals. A total of 71 patients (mean age 68 years, 76% smokers) demonstrating peri‐implantitis at one or more implants as evidenced by bleeding and/or pus on probing and bone loss amounting to >3 threads on Brånemark implants and 49 controls (mean age 66 years, 45% smokers) with clinical healthy mucosa and no bone loss around the implants were recruited for the study. The titanium implants, ad modum Brånemark, had been in function for at least 2 years. Mouthwash samples were collected and used for genotyping of the bi‐allelic polymorphisms IL‐1A^?889, IL‐1B⁺³⁹⁵³, IL‐1B^?511 and a variable number of tandem repeat IL‐1RN gene polymorphisms using PCR technique. Results: Significant differences were found in the carriage rate of allele 2 in the IL‐1RN gene between peri‐implantitis patients and controls (56.5% vs. 33.3%, respectively; odds ratios (OR) 2.6; 95% confidence interval (CI) 1.2–5.6; P=0.015). Logistic regression analysis taking smoking, gender and age into account confirmed the association between the IL‐1RN allele 2 carriers and peri‐implantitis (OR 3; 95% CI 1.2–7.6; P=0.02). Conclusions: Our results provide evidence that IL‐1RN gene polymorphism is associated with peri‐implantitis and may represent a risk factor for this disease.     

Development of an animal model for Aggregatibacter actinomycetemcomitans biofilm-mediated oral osteolytic infection: a preliminary study

Background: Biofilm‐induced inflammatory osteolytic oral infections, such as periodontitis and peri‐implantitis, have complex etiology and pathogenesis. A significant obstacle to research has been the lack of appropriate animal models where the inflammatory response to biofilms can be investigated. The aim of this study is to develop a novel animal model to study the host response to Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans)–biofilm colonizing titanium implants. Methods: Titanium implants were inoculated in vitro with A. actinomycetemcomitans, establishing a biofilm for 1 to 3 days. Biofilm‐inoculated and control implants were transmucosally placed into rat hard palate or alveolar ridge. Analysis included documentation of clinical inflammation, polymerase chain reaction, and culture detection of A. actinomycetemcomitans and microcomputed tomography quantitation of peri‐implant bone volume. Results: Viable A. actinomycetemcomitans biofilm was successfully established on titanium implants in vitro, detected by confocal laser scanning microscopy. An inflammatory response characterized by clinical inflammation, bleeding, ulceration, hyperplasia, and necrosis was observed around biofilm‐inoculated implants. A. actinomycetemcomitans was detected by polymerase chain reaction and culture analysis on 100% of biofilm‐inoculated implants for up to 3 weeks and 25% for up to 6 weeks. Microcomputed tomography analysis demonstrated significantly lower bone volume (P <0.05) around biofilm‐inoculated implants (29.6% ± 7.6%) compared to non‐inoculated implants (50.5% ± 9.6%) after 6 weeks. Conclusions: These results describe a novel animal model where A. actinomycetemcomitans biofilm was established in vitro on titanium implants before placement in rat oral cavity, leading to an inflammatory response, osteolysis, and tissue destruction. This model may have potential use for investigation of host responses to biofilm pathogens and antibiofilm therapy.     

The Current Weight of Evidence of the Microbiologic Profile Associated With Peri‐Implantitis: A Systematic Review

Background: There is currently no consensus regarding microorganisms that may be considered true peri‐implant pathogens. Therefore, the aim of this systematic review is to determine the weight of evidence for microorganisms related to peri‐implantitis based on results of association studies. Methods: This review was performed following the Preferred Reporting Items for Systematic Reviews and MetaAnalyses (PRISMA). Two independent researchers searched PubMed/Medline, Embase, and Cochrane Library databases up to August 4, 2015, for studies comparing microbiologic outcomes of subgingival biofilm samples from healthy implants and implants with peri‐implantitis. Results: A total of 799 titles was identified and 11 studies were included in this review. All data were extracted using a predefined form. Microorganisms found in increased count/abundance/frequency in peri‐implantitis belonged to Bacteria domain and viruses, and included a total of six bacterial phyla, 17 bacterial genera, 23 bacterial species, and two genera of viruses. The main bacterial species associated with peri‐implantitis are recognized as periodontal pathogens. Conclusion: Results of this systematic review suggest moderate evidence supporting association of Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia and some evidence supporting association of Prevotella intermedia and Campylobacter rectus with the etiology of peri‐implantitis.     

Peri-implant health around screw-shaped c.p. titanium machined implants in partially edentulous patients with or without ongoing periodontitis

Abstract: The relationship between periodontitis and peri‐implantitis remains a matter of debate. The present study compared, “within” randomly chosen partially edentulous patients (n=84 subjects, 97 jaws), the marginal bone loss around teeth and implants during 5 years (range 3 to 11 years) following the first year of bone remodelling. The patients had all been rehabilitated by means of screw‐shape c.p. titanium implants with a machined surface (Brånemark system^®). During the 5 years observation interval, periodontal parameters (marginal bone and attachment loss, the latter for teeth only) were collected together with data on confounding factors (smoking, oral hygiene, tooth loss). Marginal bone loss was measured through long‐cone intra‐oral radiographs. The mean “interval” bone loss was significantly (P=0.0001) higher around teeth (0.48±0.95 mm) than around implants (0.09±0.28 mm). The corresponding data for the “worst” performing tooth (0.99±1.25 mm) and implant (0.19±0.32 mm) per subject showed the same tendency. Neither attachment nor bone loss around teeth correlated with marginal bone loss around implants. This study indicated that the rate of bone loss around screw‐shape c.p. titanium implants with a machined surface (Brånemark system^® implants) was not influenced by the progression rate of periodontal destruction around the remaining teeth within the same jaw.     

Comparison of peri‐implant clinical and radiographic status around short (6 mm in length) dental implants placed in cigarette‐smokers and never‐smokers: Six‐year follow‐up results

Background

It is hypothesized that peri‐implant clinical and radiographic inflammatory parameters (probing depth [PD], bleeding on probing [BOP] and plaque index [PI]; and radiographic (crestal bone loss [CBL]) are worse among cigarette‐smokers (CS) compared with never‐smokers (NS) with short implants.

Purpose

The present 6‐year follow‐up retrospective study compared the peri‐implant clinical and radiographic parameters in CS and NS with short dental implants (6 mm in length).

Materials and methods

Fifty‐six male individuals were included. These individuals divided into 2 groups as follows: (a) Group‐1: 29 self‐reported systemically healthy CS with 48 short‐implants; and (b) Group‐2: 27 self‐reported systemically healthy NS with 43 short implants. Peri‐implant PD, PI, BOP, and CBL were measured. Group comparisons were done using the Kruskal‐Wallis test and sample size was estimated. Level of significance was set at P values < .05.

Results

In groups 1 and 2, the follow‐up durations were 6.2 ± 0.1 years and 6.1 ± 0.3 years, respectively. A cigarette smoking history of 8.9 ± 3.6 pack years was reported by individuals in Group‐1. At follow‐up, scores of peri‐implant PD, BOP, PI, and mesial and distal CBL were comparable around short implants in both groups.

Conclusion

Under strict oral hygiene maintenance protocols, short dental implants can remain functionally stable in CS in a manner similar to NS.     

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.     

Implant-supported fixed prostheses in the edentulous maxilla: 8-year prospective results

Objective: The purpose of this prospective study was to evaluate the long‐term survival and success rates of implants and screw‐retained, full‐arch prostheses placed in edentulous maxillae over 8 years of function. Materials and methods: A total of 106 Astra Tech implants were placed in the maxillae of 17 edentulous patients in a one‐stage surgical approach. After a healing period of 6 months, the patients received fixed screw‐retained bridges. Follow‐up visits, including clinical and radiographic examinations, were performed after 6 months and at yearly intervals. Implant survival, implant success, and marginal bone‐level changes were defined as the primary outcome variables. The secondary aims were to report periodontal pathogens at 5 years' follow‐up and patients' satisfaction at the 8‐year follow‐up. Results: The overall observation time was 8 years. One patient died during the study and one implant failed during the healing period, yielding an 8‐year cumulative implant survival rate of 99%. The prosthetic survival rate was 100%. The mean crestal bone loss amounted to 0.3 ± 0.72 mm. Patients' subjective evaluations demonstrated an overall high level of satisfaction. In all cases, except for one, microbiologic probing of the peri‐implant sulcus after 5 years showed no higher incidence of periodontal pathogens. Conclusions: Screw‐retained, full‐arch restorations on six implants in an edentulous maxilla are a predictable and highly successful treatment concept as observed throughout this study with an observation period of 8 years of function, in particular with respect to low crestal bone loss and high patient satisfaction. To cite this article:
Mertens C, Steveling HG. Implant‐supported fixed prostheses in the edentulous maxilla: 8‐year prospective results.
Clin. Oral Impl. Res. 22 , 2011; 464–472
doi: 10.1111/j.1600‐0501.2010.02028.x     

Food Impaction and Periodontal/Peri‐Implant Tissue Conditions in Relation to the Embrasure Dimensions Between Implant‐Supported Fixed Dental Prostheses and Adjacent Teeth: A Cross‐Sectional Study

Background: Food impaction and periodontal/peri‐implant tissue conditions were evaluated in relation to the embrasure dimensions between implant‐supported fixed dental prostheses (FDPs) and adjacent teeth. Methods: A total of 215 embrasures of 150 FDPs in 100 patients (55 males and 45 females, aged 27 to 83 years; mean age: 56 years) were included in the study. Clinical assessments of the periodontal/peri‐implant mucosal conditions, radiographic assessments of embrasure dimensions, and overall patient satisfaction were used as explanatory variables for the food impaction and periodontal/peri‐implant tissue conditions adjacent to implant‐supported FDPs in the generalized estimating equation (GEE) analysis. Results: Food impaction was reported in 96 (44.7%) of 215 embrasures between implant‐supported FDPs and adjacent teeth. Food impaction was reported more frequently in the embrasures with proximal contact loss than in those with tight contact (P = 0.009). Overall patient satisfaction was influenced negatively by food impaction in the proximal embrasures (P = 0.01). Among embrasure dimensions, only the embrasure surface area (ESA) significantly influenced food impaction (P = 0.03). Significant influences of various embrasure dimensions on the periodontal/peri‐implant mucosal conditions and bone level at the implant were found in the univariate and multivariate GEE analyses. Conclusions: Food impaction between implant‐supported FDPs and adjacent teeth occurred more frequently when proximal contact was lost and ESA increased. Food impaction negatively affected overall patient satisfaction. Embrasure dimensions influenced the periodontal/peri‐implant mucosal conditions and bone level at the implant.     

Microbiota around teeth and dental implants in periodontally healthy,partially edentulous patients: is pre‐implant microbiological testing relevant?

Meijndert L, van der Reijden WA, Raghoebar GM, Meijer HJA, Vissink A. Microbiota around teeth and dental implants in periodontally healthy, partially edentulous patients: is pre‐implant microbiological testing relevant? Eur J Oral Sci 2010; 118: 357–363. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci This study aimed to assess the prevalence of seven periodontal marker pathogens, before implant placement and 1 yr after loading, in periodontally healthy individuals and to assess the long‐term effectiveness of pre‐implant reduction of pathogens to below threshold levels. In 93 individuals needing single tooth replacement, pooled subgingival microbiological samples from standard sites were cultured and analyzed before implant treatment and 1 yr after loading. Threshold levels commonly used in periodontology to predict periodontal breakdown were applied. Subjects with levels of pathogens above these thresholds received initial periodontal treatment including systemic antibiotics when indicated. At baseline, 49.5% of periodontally healthy subjects harboured one or more marker pathogens above threshold levels. Periodontal treatment reduced the pathogen levels below threshold values in 78.3% of these initially colonized subjects. In all cases Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis were reduced to below threshold. At 1 yr after loading, periodontal pathogens were present above threshold levels in 74.1% of all subjects. It is concluded that in almost half of periodontal healthy individuals the subgingival biofilm harbours periodontal pathogens above threshold values. Long‐term effectiveness of pre‐implant reduction of the selected marker pathogens appeared limited in our patient population, making pre‐implant reduction unpredictive for post‐implant levels of these pathogens. Thus, considering the applied microbiological criteria, generalized pre‐implant microbiological testing is not contributory in periodontally healthy subjects.     

Microbial Characteristics of Peri‐Implantitis: A Case‐Control Study

Background: The aim of this case‐control study is to compare oral microbiologic characteristics of patients with healthy peri‐implant conditions and patients with peri‐implantitis and to explore the influence of various patient‐ and implant‐related factors on microbiologic characteristics. Methods: Peri‐implant submucosal microbial samples were collected from 85 patients with peri‐implantitis (cases) and from 69 patients with only implants with healthy peri‐implant conditions (controls). Samples were analyzed using culturing techniques. Multivariable logistic regression was used to explore the association of disease status and various patient‐ and implant‐related factors (sex, patient age, smoking, number of remaining teeth, percentage of teeth with bone loss, implant function time, implant surface, and presence of plaque) with microbiologic characteristics. Results: Peri‐implant disease status was significantly associated with the submucosal presence of Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Tannerella forsythia (Tf), and Fusobacterium nucleatum (Fn). The association with disease status was most obvious for Pi (odds ratio [OR]: 15.1; 95% confidence interval [CI]: 5.1 to 45.3) and Tf (OR: 13.3; 95% CI: 5.4 to 32.5). The prevalence of Aggregatibacter actinomycetemcomitans and Staphylococcus species was very low. Conclusions: The periodontal pathogens Pg, Pi, Tf, and Fn are associated with peri‐implantitis. A. actinomycetemcomitans and Staphylococcus species do not seem to play an important role in peri‐implantitis.     

Investigation of the Association Between Cement Retention and Prevalent Peri‐Implant Diseases: A Cross‐Sectional Study

Background: The aim of this study is to examine the association between retention type (cement‐retained versus screw‐retained restorations) and prevalence of peri‐implant diseases in a German university‐treated population. Methods: Data were analyzed from individuals that underwent clinical and radiographic peri‐implant examinations as part of a university‐based cross‐sectional study from September 2011 to October 2012. Results: Data from 139 individuals (mean age: 57.59 years) having 394 implants were analyzed: 192 implants supporting single crowns and 202 fixed partial dentures. Overall, 11.9% of the participants had peri‐implantitis, whereas 68.9% had peri‐implant mucositis. Crude odds ratios (95% confidence intervals) for peri‐implantitis and peri‐implant mucositis for cement‐ versus screw‐retained restorations were 1.43 (0.45, 4.60) and 0.89 (0.53, 1.48), respectively. Results remained non‐significant in multivariable models adjusting for type of restoration and smoking (all P values >0.50). There was also no effect of splinting restorations on disease prevalence in adjusted analyses (P values >0.32). Conclusions: In this university‐treated sample, there is no association between the type of prosthesis retention and peri‐implant diseases. Current findings show that, when appropriate selection and removal of cement is performed, cement retention is not a risk indicator for peri‐implant diseases.