Oral bacterial colonization on dental implants restored with titanium or zirconia abutments: 6-month follow-up.

OBJECTIVE: This investigation aimed to characterize in a 6-month follow-up the microbial profile of implants restored with either titanium or zirconia abutments at the genus or higher taxonomic levels. METHODS: Twenty healthy individuals indicative for implant-retained single restorations were investigated. Half of participants were restored with titanium and half with zirconia abutments. Biofilm was collected from the implant-related sites after 1, 3, and 6 months of loading. The 16S rDNA genes were amplified and sequenced with Roche/454 platform. RESULTS: A total of 596 species were identified in 360 samples and grouped in 18 phyla and 104 genera. Titanium- or zirconia-related sites as well as teeth showed similar total numbers of operational taxonomic units (OTUs) colonizing surfaces over time. Firmicutes, Proteobacteria, Fusobacteria, Bacteroidetes, and Actinobacteria were the most prevalent phyla with significant differences between different surfaces and time point. Unclassified genera were found in lower levels (1.71% up to 9.57%) on titanium and zirconia samples when compared with teeth, with no significant differences. CONCLUSION: Titanium- and zirconia-related surfaces are promptly colonized by a bacterial community similar to those found in the remaining adjacent teeth. Results suggest a selective adhesion of different bacterial genotypes for either titanium or zirconia surfaces. Data also indicate a significant interaction between the relative effects taxa, time point, and sampling site. CLINICAL RELEVANCE: The present study disclosed a wider spectrum of microorganisms colonizing either titanium- or zirconia-related microbiomes in very early stage of implant colonization, revealing differences and suggesting a probably specific mechanism for selective bacterial adhesion.

Randomized controlled clinical pilot study of all-ceramic single-tooth implant reconstructions: clinical and microbiological outcomes at one year of loading.

OBJECTIVE: To test whether or not pink veneering of the submucosal part of zirconia abutments influences clinical, microbiological and histological outcomes of cemented implant-supported single crowns (ISSC). MATERIALS AND METHODS: A total of 20 patients with one single-tooth implant in the esthetic zone were included. Implants were randomly restored with either pink-veneered zirconia abutments (test group; n = 10) or non-veneered white zirconia abutments (control group; n = 10) and with adhesively cemented all-ceramic crowns. At the 6-month follow-up, soft tissue biopsies were prepared for histological evaluation and microbiological samples were collected around abutments and the respective contra-lateral teeth (in 10 of 20 patients). One year after the initiation of loading, clinical parameters were assessed. Robust linear mixed model and cumulative linked mixed model analyses were performed to investigate the effect of group and time-point on clinical and biological outcomes. RESULTS: Clinical evaluations revealed stable peri-implant soft tissues in terms of probing pocket depth, but a high BOP index (87.5% control; 80.0% test). No statistically significant differences were observed between the test and control group for any outcome measure (P > 0.05). No major biological complications occurred during the observation period. Histological samples revealed a remarkable degree of inflammation in both groups without clear differences in qualitative histological features. Microbiological evaluation demonstrated a slightly higher bacterial count at implants compared to natural teeth at one year of loading without marked differences between groups. CONCLUSION: Limited by a small sample size and a relatively short observation period, pink-veneered zirconia abutments exhibited similar clinical, histological and microbiological outcomes as non-veneered zirconia abutments supporting cemented single crowns.

Comparison of Clinical and Radiographic Outcomes of Platform-Switched Implants with a Rough Collar and Platform-Matched Implants with a Smooth Collar: A 1-Year Randomized Clinical Trial.

PURPOSE: The aim of this study was to evaluate and compare the clinical and radiographic outcomes of single implants with a platform-switched rough collar (PSRC) and a platform-matched smooth collar (PMSC). MATERIALS AND METHODS: Twenty-six patients missing a tooth in the anterior maxilla (through the premolars) were randomly assigned to the PSRC or the PMSC group. All implants were placed in a flapless approach and restored with an early loading protocol. Clinical measurements were performed at surgery, loading, and at 3, 6, and 12 months after loading. In addition, radiographic evaluations were carried out using standardized periapical radiographs and cone beam computed tomography. Patient satisfaction surveys were completed, and microbial analysis with DNA probes was performed. RESULTS: The implant survival rate was 100% for both groups. The mean marginal bone level (MBL) was significantly higher in the PSRC group compared to the PMSC group at all time points. From the 2-week postoperative visit to 1 year postloading, the mean MBL change in the PSRC group was 0.21 ± 0.56 mm and in the PMSC group it was 0.74 ± 0.47 mm. Soft tissue profiles were stable over time, with no significant differences between groups. There were no significant differences between groups in the number of microbial species seen. Patients in both groups were highly satisfied with postoperative and postprosthetic experiences. CONCLUSION: In this study, the PSRC method preserved marginal bone by a mean of 0.53 mm more than the standard PMSC protocol. Within the limitations of the present study, it can be concluded that the PSRC protocol may be beneficial in marginal bone preservation. Longitudinal studies are needed to verify the long-term effects of this approach.

Long-term follow-up of turned single implants placed in periodontally healthy patients after 16 to 22 years: microbiologic outcome.

BACKGROUND: Survival rates in implant dentistry today are high, although late failures do occur for many reasons, including peri-implant infections. The primary objective of this study is to investigate microbiota around single turned implants after 16 to 22 years. Secondary objectives are to compare teeth and implants and to correlate microbiologic, radiographic, and clinical parameters. METHODS: A total of 46 patients with single implants were invited for a clinical examination. Clinical data were collected from implants and contralateral natural teeth. Radiographic bone level was measured around implants. Microbiologic samples were taken from implants, contralateral teeth, and the deepest pocket per quadrant. Samples were analyzed with DNA-DNA hybridization including 40 species. Statistical analysis was performed using Wilcoxon signed-rank tests, McNemar tests, and Spearman correlation coefficients with a 0.05 significance level. RESULTS: Mean follow-up was 18.5 years (range 16 to 22 years). Tannerella forsythia (1.5 × 10(5)) and Veillonella parvula (1.02 × 10(5)) showed the highest concentrations around implants and teeth, respectively. Porphyromonas gingivalis, Prevotella intermedia, and T. forsythia were significantly more present around implants than teeth. Mean counts were significantly higher around implants than teeth for Parvimonas micra, P. gingivalis, P. intermedia, T. forsythia, and Treponema denticola. Total DNA count was correlated to interproximal bleeding index (r = 0.409) and interproximal probing depth (r = 0.307). No correlations were present with plaque index or radiographic bone level. CONCLUSIONS: In the present study, bacterial counts around single implants in periodontally healthy patients are rather low. Although pathogenic bacteria are present, some in higher numbers around implants than teeth (five of 40), the majority of implants present with healthy peri-implant tissues without progressive bone loss.

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

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.

The microbiota associated with implants restored with platform switching: a preliminary report.

BACKGROUND: It was demonstrated that implants restored according to a platform-switching concept presented less crestal bone loss than implants restored with standard protocols. The aim of this study is to examine differences between the composition of the peri-implant microbiotas associated with implants restored with the platform-switching approach and implants restored with a standard internal connection protocol. METHODS: A total of 48 implants were examined in 18 subjects: 33 implants were restored with platform switching, and 15 implants were restored using the traditional approach. Thirty-six months after prosthetic loading, subgingival plaque samples were taken from the mesio- and disto-buccal aspects of each implant and from one tooth adjacent to one of the implants in each subject. The levels of 40 subgingival species were measured using checkerboard DNA-DNA hybridization. Microbiologic parameters were averaged within each subject and across subjects in each clinical group (platform switching versus control) and site category (implants versus teeth) separately. The significance of differences between clinical groups and site categories was determined using the Mann-Whitney test and the Wilcoxon test, respectively. RESULTS: There were no statistically significant differences between groups for any of the species. The platform-switching group showed a small trend for lower levels of early colonizer members of the Actinomyces, purple and yellow complexes, Campylobacter species, Tannerella forsythia (previously T. forsythensis), and Porphyromonas gingivalis. Teeth and implants presented similar microbial profiles. CONCLUSION: The results of the study suggest that the difference in bone crest resorption between implants restored with platform switching compared to traditionally restored implants is not associated with differences in the peri-implant microbiota.

Internal decontamination of dental implants: an in vivo randomized microbiologic 6-month trial on the effects of a chlorhexidine gel.

BACKGROUND: Microbial penetration inside an implant's internal cavity results in a bacterial reservoir that has been associated with an area of inflamed connective tissue facing the fixture-abutment junction. The aim of the present clinical trial was to evaluate the effectiveness of a 1% chlorhexidine gel on the internal bacterial contamination of implants with screw-retained abutments. METHODS: Thirty subjects (age range: 27.3 to 54.2 years) underwent single implant restoration. Three months after prosthodontic restoration, the modified sulcus bleeding index, modified plaque index, full-mouth plaque score, and full-mouth bleeding score were recorded. Microbiologic samples were also collected from the internal part of each fixture. Subjects were then divided into two equal groups: control and test groups (CG and TG, respectively). The CG had the abutment screwed and the crown cemented without any further intervention. Conversely, the TG had the internal part of the fixture filled with a 1% chlorhexidine gel before the abutment placement and screw tightening. Six months later, microbiologic and clinical procedures were repeated in both groups. Total bacterial count and multiplex polymerase chain analysis were performed to detect specific pathogens. RESULTS: Clinical parameters remained stable throughout the study. From baseline to the 6-month examination, the total bacterial counts underwent a significant reduction in the TG (P<0.05). Detection of the single pathogen species did not show any significant differences. However, periopathogens were detected more frequently in the CG. CONCLUSION: The application of a 1% chlorhexidine gel seemed to be an effective method to reduce bacterial colonization of the implant cavity over a 6-month period.

Early soft tissue healing around one-stage dental implants: clinical and microbiologic parameters.

BACKGROUND: Despite the potential significance of early soft tissue healing to long-term outcomes, this aspect of one-stage dental implants has not been investigated. The purpose of this prospective study was to characterize clinical and microbiologic parameters of early soft tissue healing around dental implants placed following a one-stage protocol. METHODS: Twenty-one patients (11 females and 10 males, aged 18 to 78 years; two smokers) needing a single implant were included. Clinical parameters included probing depth, buccal flap thickness, papilla height, and bleeding on probing. Subgingival plaque samples were obtained pre- and postoperatively and analyzed using molecular techniques. RESULTS: The newly formed peri-implant sulcus probing depth remained fairly stable from 4 to 12 weeks (P > 0.05). There was no statistically significant association between flap thickness or papillary height and number of implant bleeding sites at 12 weeks (P > 0.05). Detection of known periodontal pathogens was rare. Fusobacterium nucleatum was present in 17 patients prior to surgery, and 71% of them became carriers of this bacterium at the implant site by the second postoperative week. The number of F. nucleatum-positive subjects around the implant was significantly lower than the number of F. nucleatum-positive subjects around teeth (P < 0.05). CONCLUSIONS: Peri-implant soft tissue clinical maturity may be established as early as 4 weeks following implant placement by a one-stage surgical protocol; neither preexisting flap thickness nor papillary height seemed to influence newly forming peri-implant sulcus depth or bleeding on probing prevalence. For the most part, the newly created peri-implant crevices were colonized by specific bacteria within 2 weeks.

[Microbiological study on the prognosis of immediate implant and periodontal disease]. / Mikrobiologische Untersuchung zur Ermittlung des Erfolges der Sofortimplantation im parodontal geschädigten Gebiss.

AIM: The aim of the present study was to investigate the prevalence of periodontal marker organisms and specific interleukin-1 (IL-1) gene polymorphisms (which show a close association with periodontitis) and their effect on the success of immediate implant placement postextraction in the patient with periodontal disease. PATIENTS AND METHODS: A group of 59 patients (22 men and 37 women aged 20-81 years, median age 55 years, 18 smokers) with chronic adult periodontitis participated in the study which included a 1-year observation period postoperatively. Prior to tooth extraction two DNA samples were obtained for the microbiological diagnosis of five anaerobic gram-negative pathogens (Haemophilus actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythensis, Prevotella intermedia sensu stricto, Treponema denticola) and to identify the IL-1 gene polymorphisms. Patients were treated with a total of 95 immediate dental implants (26 Ankylos/Friadent and 69 Camlog Root-Line/Camlog Biotechnologies) placed into extraction sites, 78 of which were loaded immediately. After 1 year four failures were observed; all of these patients were smokers. RESULTS: None of these patients showed a positive IL-1 genotype; periodontal marker organisms were only found in one patient. No significant difference was seen in the microbiological pathogens between smokers and nonsmokers. Of 59 patients, 23 (39%) tested positive for IL-1 genotype polymorphism. Smoking was shown to increase the risk of implant failure. No association was observed between failures and the IL-1 gene polymorphisms or pathogens. CONCLUSION: In conclusion, our study shows that periodontally infected sites do not seem to be a contraindication for immediate implantation.

In vitro evaluation of bacterial leakage along the implant-abutment interface of different implant systems.

PURPOSE: Microbial leakage and colonization between implants and their abutments may cause inflammatory reactions in the peri-implant tissues. This study evaluated microbial leakage at the implant-abutment interface with a new in vitro model. MATERIALS AND METHODS: Bacterial leakage was tested during dynamic loading in a 2-axis chewing simulator. The authors theorized that dynamic loading would decrease the stability of the implant-abutment connections and thereby lead to bacterial penetration along the gap. Five different implant systems with 8 standard implant-abutment combinations for single molar crowns were tested. The internal aspects of the implants were inoculated with a bacterial suspension and connected to the superstructure with the recommended torque. The specimens were immersed in a nutrient solution and loaded with 1,200,000 cycles of 120 N in the chewing simulator. RESULTS: Statistically significant differences (P < or = .05) between implant systems with respect to number of chewing cycles until bacterial penetration were found. DISCUSSION: The degree of penetration in a specific implant system presumably is a multifactorial condition dependent on the precision of fit between the implant and the abutment, the degree of micromovement between the components, and the torque forces used to connect them. CONCLUSION: It was concluded that the newly developed test model is a sensitive tool for the detection of differences between current implant systems with respect to their ability to prevent bacterial penetration at the implant-abutment interface under dynamic loading conditions.

Microbiota of successful osseointegrated dental implants.

BACKGROUND: The long-term survival of dental implants depends, in part, on control of bacterial infection in the peri-implant region. Periodontal pathogens colonized implants symptomatic through infection, whereas the microbiota of successful implants was similar to that of periodontal health. This study examined the impact on the peri-implant microbiota of crown restorations; implant type; length of time of loading; history of implant or periodontal infections; and whether implants replaced single or multiple teeth. It was of particular interest to evaluate implant colonization by species in a newly described red complex of periodontal pathogens, Porphyromonas gingivalis and Bacteroides forsythus. METHODS: This study sampled 43 partially edentulous subjects with successfully osseointegrated titanium root-form dental implants. Eighty-one (81) non-submerged and 20 submerged asymptomatic implants, 83 crowned, and 36 uncrowned teeth were sampled from peri-implant or subgingival sites. The microbiota of samples was evaluated using whole genomic DNA probes in a checkerboard assay to 23 subgingival species. RESULTS: Implants were colonized principally by oral streptococci, capnocytophagae, Veillonella parvula, Peptostreptococcus micros, and Fusobacterium nucleatum. The periodontal species, P. gingivalis, B. forsythus, Prevotella intermedia, Prevotella nigrescens, and Campylobacter rectus were detected in a few subjects. The microbiota around crowned implants and crowned teeth was similar. Streptococcus oralis, P. intermedia, and Selenomonas noxia were elevated in samples from uncrowned teeth compared to crowned teeth and implants. Microbial complexity increased as loading time increased, but colonization by periodontal pathogens, including red complex species, was higher in subjects with previous periodontal disease. No differences were observed in the microbiota of 1- and 2-stage implants, or between implants supporting single or multiple restorations. CONCLUSIONS: While presence of crowns had only a minor impact on the peri-implant microbiota, microbial changes were observed the longer the implants had been in function and in those patients with a history of periodontal or peri-implant infections. A history of periodontitis had a greater impact on the peri-implant microbiota than implant loading time. The major influence on the peri-implant microbiota was, however, the microbiota on remaining teeth. P. gingivalis and B. forsythus, red complex periodontal pathogens, colonized several implants, although all implants were successfully osseointegrated.

Bacterial leakage into and from prefabricated screw-retained implant-borne crowns in vitro.

A mean gap of less than 4 microm following laboratory procedures and continuous loading was demonstrated in prefabricated crowns of the Ha-Ti implant system in earlier studies. The clinical relevance of such high precision in maintaining inflammation free marginal mucosa is yet to be determined. In this present investigation, the complete assembly of Ha-Ti implants including prefabricated screw-retained crowns was tested for bacterial leakage under controlled conditions in vitro. The gaps were shown not to be a barrier for Staphylococcus aureus which were used as test bacteria. Bacterial leakage through these gaps from the environment to the interior of the assembly and vice versa was observed within 24-120 h. The main path of bacterial penetration was possibly found to be through the transversal screw hole and not through the marginal gap of the prefabricated crowns.

Endodontic pathology leading to implant failure--a case report.

This case report documents both the placement of a single implant into an alveolar ridge site and the failure of the implant due to bacterial contamination from an endodontic lesion. After placement of the fixture using osteotomes, the adjacent bicuspid developed periapical pathology following prior crown preparation. This root-end inflammatory process proceeded to involve the mesial surface of the implant. Although endodontic therapy on the devitalized tooth was performed within one week, an osteitis developed around the implant. One month after placement, the fixture had to be removed to prevent additional sequela. The osteotomy site appeared to heal uneventfully, allowing for the placement of a tooth-supported, fixed, partial prosthesis.