Biology of teeth and implants: Host factors - pathology, regeneration, and the role of stem cells

In chronic periodontitis and peri-implantitis, cells of the innate and adaptive immune systems are involved directly in the lesions within the tissues of the patient. Absence of a periodontal ligament around implants does not prevent a biologic process similar to that of periodontitis from affecting osseointegration. Our first focus is on factors in the biology of individuals that are responsible for the susceptibility of such individuals to chronic periodontitis and to peri-implantitis. Genetic factors are of significant importance in susceptibility to these diseases. Genetic factors of the host affect the composition of the oral microbiome in the same manner that they influence other microbiomes, such as those of the intestines and of the lungs. Our second focus is on the central role of stem cells in tissue regeneration, in the functioning of innate and adaptive immune systems, and in metabolism of bone. Epithelial cell rests of Malassez (ERM) are stem cells of epithelial origin that maintain the periodontal ligament as well as the cementum and alveolar bone associated with the ligament. The tissue niche within which ERM are found extends into the supracrestal areas of collagen fiber-containing tissues of the gingivae above the bony alveolar crest. Maintenance and regeneration of all periodontal tissues involves the activity of a variety of stem cells. The success of dental implants indicates that important groups of stem cells in the periodontium are active to enable that biologic success. Successful replantation of avulsed teeth and auto-transplantation of teeth is comparable to placing dental implants, and so must also involve periodontal stem cells. Biology of teeth and biology of implants represents the biology of the various stem cells that inhabit specialized niches within the periodontal tissues. Diverse biologic processes must function together successfully to maintain periodontal health. Osseointegration of dental implants does not involve formation of cementum or collagen fibers inserted into cementum - indicating that some stem cells are not active around dental implants or their niches are not available. Investigation of these similarities and differences between teeth and implants will help to develop a better understanding of the biology and physiologic functioning of the periodontium.

Biology of teeth and implants: The external environment, biology of structures, and clinical aspects

For the past several thousand years, until development of the titanium dental implant, only a few missing teeth were replaced successfully in a very small number of individuals. Nowadays, placement of dental implants has become sufficiently commonplace that there is a need to interchange information between what we know about periodontal health and disease and what we know about health and disease involving dental implants. This review discusses the similarities and differences between teeth and dental implants with regards to anatomy, biology, physiology, and pathologic processes. The concept of biologic width is discussed in the context of interaction of periodontal and peri-implant tissues with microbial products produced by periodontal biofilms. The periodontal microbiome is discussed as networks of organisms interacting not only with periodontal and peri-implant tissues, but also with each other as networks of competing organisms. Overall, the transfer of biologic knowledge from what we know about peri-implantitis and what we know about periodontitis should help to develop new directions for biologic understanding about both health and disease of teeth and dental implants.

Can extra-short dental implants serve as alternatives to bone augmentation? A preliminary longitudinal randomized controlled clinical trial

OBJECTIVE

A randomized trial to assess clinical and radiographic outcomes of short versus standard dental implants placed with concomitant vertical bone augmentation.

METHOD AND MATERIALS

Patients requiring dental implants were randomized to receive either 6-mm implants (experimental) or 10-mm implants with vertical augmentation (control). Custom load-bearing healing abutments were connected to allow for indirect resonance frequency analysis measurements. Standardized radiographs were taken at implant placement (baseline), and at 3 and 12 months. Implants were restored at 3 to 6 months, and final measurements were taken at 12 months.

RESULTS

Fifty patients with 25 implants per group were included. Five implants failed, four experimental and one control (84% and 96% cumulative survival rate, respectively). Short implants required significantly less surgical time (51.6 ± 23 versus 68.5 ± 35 minutes, P = .05). Implant stability quotients at baseline (67.9 ± 8.3 experimental and 70.8 ± 7.6 control, P = .215) and 12 weeks (70.17 ± 7.4 and 72.03 ± 5.9, respectively, P = .513) were similar and unchanged. Positive correlation was found between the two measurement methods (r2 = .6, P = .025). One-year average marginal bone loss was slightly lower for the experimental group (0.6 ± 0.16 mm) compared to the control group (0.86 ± 0.19 mm); however, this was not statistically significant (P = .287).

CONCLUSION

Short dental implants may offer an alternative for implant placement in an atrophic jaw; however, they are associated with reduced first-year survival rate. Short dental implants should be used judiciously in light of this potential predicament, and alternatives assessed.

Radiologic evaluation of bone loss at implants with biocide coated titanium abutments: a study in the dog

The objective of the present study is to evaluate bone loss at implant abutments coated with a soda-lime glass containing silver nanoparticles subjected to experimental peri-implantitis. Five beagle dogs were used in the experiments, 3 implants were installed in each quadrant of the mandibles. Glass/n-Ag coted abutments were connected to implant platform. Cotton floss ligatures were placed in a submarginal position around the abutment necks and the animals were subject to a diet which allowed plaque accumulation, and after 15 weeks the dogs were sacrificed. Radiographs of all implant sites were obtained at the beginning and at the end of the experimentally induced peri-implantitis. The radiographic examination indicated that significant amounts of additional bone loss occurred in implants without biocide coating, considering both absolute and relative values of bone loss. Percentages of additional bone loss observed in implants dressed with a biocide coated abutment were about 3 times lower (p<0.006 distal aspect; and p<0.031 at mesial aspect) than the control ones. Within the limits of the present study it seems promising the use of soda-lime glass/nAg coatings on abutments to prevent peri-implant diseases.

A comprehensive and critical review of dental implant prognosis in periodontally compromised partially edentulous patients

OBJECTIVES

The outcome of implant treatment in periodontally compromised partially edentulous patients has not been completely clarified. Therefore, the aim of the present study was to perform, applying a systematic methodology, a comprehensive and critical review of the prospective studies published in English up to and including August 2006, regarding the short-term (<5 years) and long-term (>or=5 years) prognosis of osseointegrated implants placed in periodontally compromised partially edentulous patients.

MATERIAL AND METHODS

Using The National Library Of Medicine and Cochrane Oral Health Group databases, a literature search for articles published up to and including August 2006 was performed. At the first phase of selection the titles and abstracts and at the second phase full papers were screened independently and in duplicate by the three reviewers (I. K. K., S. K., I. F.).

RESULTS

The search provided 2987 potentially relevant titles and abstracts. At the first phase of evaluation, 2956 publications were rejected based on title and abstract. At the second phase, the full text of the remaining 31 publications was retrieved for more detailed evaluation. Finally, 15 prospective studies were selected, including seven short-term and eight long-term studies. Because of considerable discrepancies among these studies, meta-analysis was not performed.

CONCLUSIONS

No statistically significant differences in both short-term and long-term implant survival exist between patients with a history of chronic periodontitis and periodontally healthy individuals. Patients with a history of chronic periodontitis may exhibit significantly greater long-term probing pocket depth, peri-implant marginal bone loss and incidence of peri-implantitis compared with periodontally healthy subjects. Even though the short-term implant prognosis for patients treated for aggressive periodontitis is acceptable, on a long-term basis the matter is open to question. Alterations in clinical parameters around implants and teeth in aggressive periodontitis patients may not follow the same pattern, in contrast to what has been reported for chronic periodontitis patients. However, as only three studies comprising patients treated for aggressive periodontitis were selected, more studies, specially designed, are required to evaluate implant prognosis in this subtype of periodontitis. As the selected publications exhibited considerable discrepancies, more studies, uniformly designed, preferably longitudinal, prospective and controlled, would be important.

A systematic review of the effectiveness of bone collectors

PURPOSE

Bone collectors are used to harvest bone debris for grafting procedures during implant surgery. The particulate bone debris gathered through filtration has been frequently used in minor regenerative surgical procedures. Nevertheless, the biological potency of such grafts is still unclear. The objective of this study was to systematically review the use of bone collectors in implant dentistry, focusing on the quantity, quality, and bacterial contamination of the bone collected.

MATERIALS AND METHODS

Following the production of a detailed protocol, screening and quality assessment of the literature were conducted in duplicate and independently. The outcome measures that were assessed were: (1) quantity of collected debris, (2) quality of the collected bone debris, and (3) bacterial contamination.

RESULTS

There is a limited amount of information on the nature of bone obtained through collectors. Eleven studies satisfied the inclusion criteria. Bone collectors are able to retain a small amount of bone for minor surgical procedures. The presence of vital bone cells has not been demonstrated routinely, while consistent bacterial contamination has been observed.

DISCUSSION

Bone collected through bone filters appears to be sufficient for small regenerative procedures. Clinicians should bear in mind that presence of bacterial pathogens is always shown with the use of bone collectors. Presurgical chlorhexidine oral rinsing and a strict aspiration protocol must be used to minimize the bacterial contamination of the debris collected.

CONCLUSIONS

Although bone collectors are capable of amassing small amounts of bone, the vitality of this bone could not be consistently demonstrated and the collected debris was always contaminated by bacteria. Therefore, the bone debris amassed in bone collectors is not an ideal grafting material and should be utilized with caution.

Neodymium:yttrium aluminum garnet laser irradiation with low pulse energy: a potential tool for the treatment of peri-implant disease

Bacterial contamination may seriously compromise successful implant osteointegration in the clinical practice of dental implantology. Several methods for eliminating bacteria from the infected implants have been proposed, but none of them have been shown to be an effective tool in the treatment of peri-implantitis. In the present study, we investigated the efficacy of pulsed neodymium:yttrium aluminum garnet laser irradiation (Nd:YAG) in achieving bacterial ablation while preserving the surface properties of titanium implants. For this purpose, suspensions of Escherichia coli or Actinobacillus (Haemophilus) actinomycetemcomitans were irradiated with different laser parameters, both streaked on titanium implants, and in broth medium. It was found, by light and atomic force microscopy, that Nd:YAG laser, when used with proper working parameters, was able to bring about a consistent microbial ablation of both aerobic and anaerobic species, without damaging the titanium surface.

Prosthodontic management of edentulous patient with limited oral access using implant-supported prostheses: A clinical report

Limited oral access presents a unique challenge to prosthodontic treatment. An edentulous patient who developed microstomia after a maxillary lip resection is presented. The clinical procedure and the rationale for the treatment approach using implanted-supported overdentures are discussed.

Feasibility and Influence of the Microgap of Two Implants Placed in a Non-Submerged Procedure: A Five-Year Follow-Up Clinical Trial

BACKGROUND

The aim of this study was to evaluate the feasibility of using a two-piece implant system in a non-submerged procedure and to study the impact of the microgap between the implant and abutment.

METHODS

Sixty edentulous patients (Cawood Class V-VI) participated in this study. After randomization, 20 patients received two two-piece implants placed in a non-submerged procedure, 20 patients received two two-piece implants placed in the traditional submerged procedure, and 20 patients were treated with two one-piece dental implants placed in the traditional non-submerged procedure. The implants were placed in the mandible for overdenture treatment. A standardized clinical evaluation was performed and radiographs were taken immediately after denture insertion and yearly up to 5 years. Peri-implant samples were collected 12, 36, and 60 months after loading with sterile paper points and analyzed for the presence of putative periodontal pathogens using culture techniques.

RESULTS

One two-piece implant of the non-submerged group and one two-piece implant of the submerged group were lost after 6 and 12 months, respectively. After 5 years of functioning, no significant clinical, radiological, or microbiological differences were found between the three groups. No association was found between the level of the microgap and the amount of bone loss.

CONCLUSIONS

The results of this study indicate that dental implants designed for a submerged implantation procedure can also be used in a non-submerged procedure and may be as predictable as when used in a submerged procedure or as one-piece implants. The microgap at the crestal level in two-piece implants does not appear to have an adverse effect on the amount of peri-implant bone loss.

Mit Knochenkollektor bei dentaler Implantation gewonnenes Knochenmaterial

BACKGROUND

Simultaneous implantation and augmentation using autogenous bone collected during implant surgery is a well-established procedure in oral implantology. The aims of this study were (1) to identify any bacterial contamination of bone obtained with a bone collector, and (2) to verify the antimicrobial effect of rinsing the bone collector with a 0.1% chlorhexidine solution prior to augmentation.

MATERIAL AND METHODS

A total of 39 patients undergoing a simultaneous implantation and augmentation procedure were examined. All patients rinsed their mouths with a 0.1% chlorhexidine solution for 2 min prior to surgery. Bone was collected with the Osseous Coagulum Trap, while saliva was collected with a separate suction tip. Once bone collection was complete a microbiological swab was taken from the bone collector (sample 1); before the bone was taken from it 200 ml of a 0.1% chlorhexidine solution was aspirated into the collector, after which the bone was removed and the collector sieve was (sample 2) sent for microbiological analysis which included aerobic and anaerobic cultivation of microorganisms and their identification and semiquantitative assessment of microbial growth.

RESULTS

Before the collector was rinsed with chlorhexidine microbial contamination was found in 34 (82.7%) of the 39 samples, and 37 different microbial species were identified in cultures. When the collector had been rinsed with 200 ml 0.1% chlorhexidine a significantly lower rate of microbial contamination was found: 66.7% of the samples were sterile.

CONCLUSIONS

Despite separate suction techniques for bone dust and saliva and preoperative use of a chlorhexidine mouthwash, bacterial contamination of bone obtained from the mouth with a bone collector has to be anticipated. Not only the physiological bacteria of the oral flora, but also the microorganisms frequently associated with implant failure can be found. Rinsing the bone collector with 200 ml of a 0.1% chlorhexidine solution significantly reduces microbial contamination. The effects on bone vitality must be studied before routine rinsing with chlorhexidine can be recommended.

Long-term follow-up of osseointegrated titanium implants using clinical, radiographic and microbiological parameters

The aim of this study was to longitudinally follow up osseointegrated titanium implants in partially dentate patients by clinical, radiographic and microbiological parameters in order to evaluate possible changes in the peri-implant health over time. Fifteen individuals treated with titanium implants, ad modum Brånemark, and followed for ten years were included in the study. Before implant placement ten years previously, the individuals had been treated for advanced periodontal disease and thereafter been included in a maintenance care program. The survival rate of the implants after ten years was 94.7%. The bone loss was 1.7 mm when using the abutment-fixture junction as a reference point. Of the individuals, 50% were positive for plaque at the implants. Bleeding on sulcus probing was present at 61% of the implant surfaces. Ten years previously, the individuals had been carriers of putative periodontal pathogens, such as Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, Capnocytophaga spp. and Campylobacter rectus, and were also carriers of these species at the current examination. The results of the present study suggest that the presence of these putative periodontal pathogens at implants may not be associated with an impaired implant treatment. These species are most likely part of the normal resident microbiota of most individuals and may therefore be found at random at both stable and progressing peri-implant sites.

The effects of an immediately pre-surgical chlorhexidine oral rinse on the bacterial contaminants of bone debris collected during dental implant surgery

Dental implant surgery produces bone debris that can be used in the "simultaneous augmentation" technique. Although this debris is contaminated with oral bacteria, a stringent aspiration protocol has been shown to reduce the levels of contamination. Chlorhexidine mouthrinse is a well-proven antibacterial rinse that has been shown to reduce infectious complications associated with dental implants. This study examined the effect of pre-operative rinsing with a 0.1% chlorhexidine digluconate mouthrinse on the bacterial contaminants present in collected bone debris bone (CBD). Twenty partially edentate patients were randomly allocated into equal groups and underwent bone collection using the Frios Bone Collector (FBC) during the insertion of two dental implants. In group T a pre-operative chlorhexidine rinse was used, whilst in group C sterile water was used. For both groups, a stringent bone collection protocol was used. Bone samples were immediately transported for microbial analysis. Colonial and microscopic morphology, gaseous requirements and identification kits were utilised for identification of the isolated microbes. Thirty-nine species were identified including a number associated with disease, in particular Actinomyces odontolyticus, Clostridium bifermentans, Prevotella intermedia, and Propionibacterium propionicum. Samples from group T (chlorhexidine mouthrinse) yielded significantly fewer organisms (P < 0.001) than in group C (sterile water mouthrinse). Gram-positive cocci dominated the isolates from both groups. It is concluded that if bone debris is to be used for the purpose of immediate simultaneous augmentation, a preoperative chlorhexidine mouthrinse should be utilised in conjunction with a stringent aspiration protocol to reduce further the bacterial contamination of CBD.

[The clinico-microbiological evaluation of the efficacy of using new drug forms of chlorhexidine--Corsodyl and Eludril--for the prevention of infectious complications in operations for endosseous implantation]

Prevention of infectious inflammatory complications of intraosseous implantation is a pressing problem. Chlorohexidine dosage forms Corsodyl and Eludril were used for this purpose. In the control group, furacillin was used. Microbiological studies showed that instillations of Corsodyl and Eludril solutions during the postoperative period did not modify normal oral microflora and led to disappearance of the most aggressive anaerobic bacteria in 1-3 days. These drugs are more effective that Listerine, and they are recommended for prevention of infectious inflammatory complications after intraosseous implantation.

Long-term evaluation of osseointegrated dental implants in the treatment of partly edentulous patients

AIM

The aim of this study was to evaluate the clinical, radiographic and microbiological status of implants after 10 years of functional load in patients treated for partial edentulism.

METHOD

15 patients, each successfully treated with 2-6 implants ad modum Brånemark placed in free-standing fixed prostheses, were included in the study.

RESULTS

Clinical evaluation revealed similar degrees of inflammation around teeth and implants. The probing pocket depth (PPD) was significantly greater around implants than around teeth. The mean marginal bone loss during 10 years of functional load was comparable to that found at the time of the 5-year follow-up. 74% of the implants remained free of marginal bone loss exceeding 1 mm. Marginal bone loss exceeding 2 mm, was found at only 5 sites. No marked differences in bacteria were present between teeth and implants. T. denticola, S. intermedia and P. micros were the commonest organisms detected around teeth and implants. The periodontal pathogens A. actinomycetemcomitans, P. gingivalis, P. intermedia, B. forsythus, and T. denticola, were found at implants with a marginal bone loss of more than 2 mm.

CONCLUSION

Our study shows that the long-term results with implants in partially dentate patients are similar to those seen in edentulous patients and that no significant change occurred after 5-year follow-up over an additional period of 5 years.

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.

Microleakage at the abutment-implant interface of osseointegrated implants: a comparative study

Microleakage can occur at the abutment-implant (A-I) interface in osseointegrated implants and may cause malodor and inflammation of peri-implant tissues. The degree of microleakage at the A-I interface of 5 implant systems was comparatively assessed at varying closing torques. Using colored tracing probes driven by a 2-atm pressure system, the interface microleakage of Brånemark, Sulzer Calcitek, 3i, ITI, and Steri-Oss implants was determined spectrophotometrically. Microleakage through the A-I interface occurred in all systems, with variability between systems, samples, and closing torques. As closing torque increased from 10 Ncm to 20 Ncm to manufacturers' recommended closing torques, microleakage decreased significantly (P < .005) for all systems. Analysis of variance showed significant interaction between closing torques and the time course of microleakage, and between systems and the time course of microleakage (P < .001). The results indicate that fluids and small molecules are capable of passing through the interface of all the A-I assemblies studied. Presumably in an in situ situation, fluids containing bacterial byproducts and nutrients required for bacterial growth may pass through the interface gap, contributing in part to clinically observed malodor and peri-implantitis.

Microbial colonization of the peri-implant environment and its relevance to long-term success of osseointegrated implants

PURPOSE

This article provides a critical examination of the literature on the colonization of the peri-implant environment and its impact on clinically significant infection, in the context of a comparison with the microbial etiology of periodontitis.

MATERIALS AND METHODS

Previous journal article bibliographies and MEDLINE searches provided comprehensive access to current literature on this topic. References that provided significant or novel advancements in knowledge were included in this review. Since it was prepared for a workshop that would examine this issue critically, this review offers provocative commentary.

RESULTS

There are many similarities in peri-implant and periodontal microbiology, both in health and in infection leading to progressive deterioration. Periodontal pockets serve as reservoirs for the colonization of implants by periodontal pathogens in partially edentulous patients. Implant design and material composition affect the colonization of implant surfaces. Infections around implants can be treated by similar strategies used for periodontitis. Investigators are beginning to adopt research designs used in periodontology to study the pathogenesis and treatment of peri-implant infections. Research in this area is impeded by the lack of surrogate variables for crestal bone resorption.

CONCLUSION

Some implants fail as a result of infection, but the frequency of failure by infection or any other cause is unknown. This paper suggests areas where much more additional research is needed, including critical consideration of strategies that have led to the past few decades' advancements in the pathogenesis of periodontitis.

[The comprehensive assessment of studies of the microbiological and cytological indices of the implant-epithelial area]

Microbiological and cytological study of the subgingival deposit at the site of introduction of intraosseous cylindrical nickelide-titanium dental implants and comparison of the findings with similar values for the adjacent teeth showed that such studies help assess the status of the implant-epithelial zone.

In vivo and in vitro study of fungal presence and growth on three tissue conditioning materials on implant supported complete denture wearers

In this study three type of tissue conditioning materials were used in vitro and in vivo to investigate the presence and growth of Candida albicans, considered to be the pathogenic member of the genus. In vitro test results of different tissue conditioners showed that they have a tendency to have an inhibiting effect on C. albicans at the third day of incubation. For the in vivo tests tissue conditioners were placed in existing maxillary prosthesis of 21 patients who had been treated with endosseous dental implants (seven in each group). The results showed that yeast forms were observed after 3 days in two patients' dentures which were relined with Fitt. Yeasts forms were also seen in three patients' dentures after 6 days, two of them relined with Fixo-gel and the other one relined with Visco-gel. The hyphal form of Candida was seen in four patients' dentures, relined with Fitt, and also in three patients' dentures, relined with Fixo-gel and Visco-gel.

Succession of putative peri-implant pathogens after root-form and plate-form implant placement in partially dentate adult monkeys

This report describes the succession of putative peri-implant pathogens in partially dentate monkeys after dental implantation and prosthetic reconstruction. Tooth and implant (6 root-end form, 4 blade-vent implants) sites in eight monkeys were monitored microbiologically and clinically during the pre-implant stage, abutment connection stage, bridge placement stage, and three and six months after the bridge placement stage. Tooth and implant sites were cleaned monthly post-extraction. Microbiological studies included dark field microscopy, selective and non-selective culture, and primary phenotypic characterization of culture isolates. After implant surgery, the median proportion of several putative peri-implant pathogens studied were significantly elevated. Following fixture placement, P. intermedia replaced P. melaninogenica as the predominant Black Pigmented Anaerobic Bacilli (BPAB) in the mouth. After abutment connection stage, levels of P. intermedia, A. actinomycetemcomitans, F. nucleatun, Haemophilus sp. and spirochetes were significantly elevated at implant and tooth sites. Three months after bridge installations, P. intermedia and A. actinomycetemcomitans remained significantly elevated at implant sites. At six months after bridge installation, levels of P. intermedia, F. nucleatum and A. actinomycetemcomitans declined significantly relative to levels at three months. Porphyromonas sp. and spirochetes were not significantly elevated although their levels correlated with gingival redness. P. intermedia, Porphyromonas sp. and spirochetes levels correlated significantly with probing depth. Correlation was detected between P. gingivalis and spirochetes; and between A. actinomycetemcomitans and F. nucleatum. Our studies show a transitional increase in levels of several organisms resembling putative pathogens of human peri-implant infection, associated with implant placements in partially edentulous mouths and supports early prophylactic interventions to control their levels.

Clinical and microbiological status of osseointegrated implants

Peri-implantitis, an inflammatory response around implants, has a poorly defined etiology and pathogenesis. To better understand the role of specific microorganisms in this disease process, clinical and microbiological parameters were examined in 24 patients with 98 osseointegrated implants. Sites were evaluated for probing depth (PD), plaque/calculus index (PI), gingival bleeding index (GBI), mobility, and crevicular fluid flow rate (CFFR). Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia in subgingival plaque were identified by latex agglutination assays. Clinically, a statistically significant correlation (P < 0.001) was observed between probing depth and the length of time an implant was present. Mobility was also significantly greater (P < 0.001) in the maxillary than in the mandibular implants. Subgingival sites harboring one of the three microorganisms had significantly greater PD, GBI, and CFFR than non-colonized sites. Implants in partially edentulous patients more frequently were colonized with P. gingivalis/P. intermedia than edentulous patients. The incidence of these microorganisms also correlated with fixture longevity. Implants present for 3 to 4 years had a significantly greater frequency of test microorganisms than implants present for 1 to 2 years. These findings suggest that microbial pathogens associated with periodontitis occur more commonly around implants exhibiting gingival inflammation (GBI) and may contribute to peri-implantitis.