Pre- and post-implantation microbiota of the tongue, teeth, and newly placed implants

Clinical and Radiological Characterization of the Long-Term Association between Unaffected/Minimally Affected Implants and History of Severe Periodontitis: A Retrospective Study

OBJECTIVES

The objectives of this research were to compare, retrospectively, the clinical and radiographic modifications of periodontal parameters and peri-implant conditions and to analyze the relationship between the changes in periodontal parameters and peri-implant conditions over a mean follow-up period of 7.6 years in a treated population with progressive/uncontrolled periodontitis and at least one unaffected/minimally affected implant.

MATERIALS AND METHODS

Nineteen partially edentulous patients having 77 implants inserted, with a mean age of 54.84 ± 7.60 years, were matched for age, gender, compliance, smoking status, general health, and implant characteristics. Periodontal parameters were evaluated in the remaining teeth. Means per teeth and implants were used when making comparisons.

RESULTS

Statistically significant differences were observed between baseline and final examination in teeth for tPPD, tCAL and MBL. Furthermore, at 7.6 years, statistically significant differences existed between implants and teeth with regard to iCAL and tCAL (p = 0.03). Multiple regression analyses were performed and revealed a significant association regarding iPPD and CBL with smoking and periodontal diagnosis. In addition, FMBS was significantly associated with CBL. Unaffected/minimally affected implants were found more frequently in the posterior mandible, with longer lengths (>10 mm) and small diameters (<4 mm), including in screwed multi-unit bridges.

CONCLUSIONS

The study results appear to reflect minimally affected mean crestal bone-level loss around implants in comparison to the marginal bone-level loss around teeth when exposed to uncontrolled severe periodontal disease over a mean period of observation of 7.6 years, while the unaffected/minimally affected implants seemed to benefit from a combination of clinical factors, including posterior mandibular position, smaller diameters, and screwed multi-unit restorations.

Comparison between flapless-guided and conventional surgery for implant placement: a 12-month randomized clinical trial

OBJECTIVES

The study was aimed at comparing implants installed with guided and conventional surgery.

MATERIAL AND METHODS

Twenty-nine total edentulous patients were selected, and maxillary contralateral quadrants were randomly assigned to static computer-aided implant surgery (S-CAIS): flapless computer-guided surgery, and conventional surgery (CS): flap surgery with conventional planning. Tomography scans were performed at baseline and 10 days after the surgery for deviation measurement, and radiography was done at baseline and after 6 and 12 months, for peri-implant bone level (PIBL) analysis. Peri-implant fluid and subgingival biofilm were collected to evaluate bone markers and periodontal pathogens.

RESULTS

S-CAIS showed less linear deviation at the apical point and the midpoint and less angular deviation (p < 0.05), with greater depth discrepancy in the positioning of the platform (p < 0.05). Higher values of vertical PIBL were observed for the S-CAIS group at baseline (p < 0.05), while lower values of horizontal PIBL were observed for CS (p < 0.05). Bone markers and Tf presented higher levels in CS (p < 0.05). Flapless S-CAIS allowed smaller linear and angular deviations than the conventional technique.

CONCLUSION

However, PIBL was higher in S-CAIS; the conventional technique led to a greater angiogenic and bone remodeling activity by elevating the angiogenic levels and bone markers.

CLINICAL RELEVANCE

Evaluating the different implant insertion techniques can guide clinical and surgical regarding the accuracy, the release pattern of bone markers, and the peri-implant bone level.

TRIAL REGISTRATION

ReBEC-RBR-8556fzp.

Effects of Bacterial Contamination on Dental Implants During Surgery: A Systematic Review

INTRODUCTION

Contamination during surgery negatively influences the prognosis of orthopaedic implants; however, it has not been proven whether contamination influences the success of dental implant treatment. The aim of the systematic review was to investigate if there exists evidence in the literature whether contamination of dental implants during surgery affects osseointegration and clinical success.

MATERIALS AND METHODS

Four data bases were used for the literature search. Primary studies and reviews regarding both clinical and preclinical research were eligible. Rating of the summarized quality of the evidence was performed.

RESULTS

Five preclinical studies were included. Because of the estimated high risk of bias in all included studies and extensive differences in study design between the included studies, meta-analysis was not performed and no reliable aggregated data could be extracted.

CONCLUSIONS

It is suggested that the scientific evidence with regard to the current topic is insufficient. Further controlled studies are warranted.

Adhesion of Porphyromonas gingivalis and Tannerella forsythia to dentin and titanium with sandblasted and acid etched surface coated with serum and serum proteins - An in vitro study

OBJECTIVE

To evaluate the adhesion of selected bacterial strains incl. expression of important virulence factors at dentin and titanium SLA surfaces coated with layers of serum proteins.

METHODS

Dentin- and moderately rough SLA titanium-discs were coated overnight with human serum, or IgG, or human serum albumin (HSA). Thereafter, Porphyromonas gingivalis, Tannerella forsythia, or a six-species mixture were added for 4h and 24h. The number of adhered bacteria (colony forming units; CFU) was determined. Arg-gingipain activity of P. gingivalis and mRNA expressions of P. gingivalis and T. forsythia proteases and T. forsythia protease inhibitor were measured.

RESULTS

Coating specimens never resulted in differences exceeding 1.1 log10 CFU, comparing to controls, irrespective the substrate. Counts of T. forsythia were statistically significantly higher at titanium than dentin, the difference was up to 3.7 log10 CFU after 24h (p=0.002). No statistically significant variation regarding adhesion of the mixed culture was detected between surfaces or among coatings. Arg-gingipain activity of P. gingivalis was associated with log10 CFU but not with the surface or the coating. Titanium negatively influenced mRNA expression of T. forsythia protease inhibitor at 24h (p=0.026 uncoated, p=0.009 with serum).

CONCLUSIONS

The present findings indicate that: a) single bacterial species (T. forsythia) can adhere more readily to titanium SLA than to dentin, b) low expression of T. forsythia protease inhibitor may influence the virulence of the species on titanium SLA surfaces in comparison with teeth, and c) surface properties (e.g. material and/or protein layers) do not appear to significantly influence multi-species adhesion.

Increase in receptor activator of nuclear factor κB ligand/osteoprotegerin ratio in peri-implant gingiva exposed to Porphyromonas gingivalis lipopolysaccharide

Background/purpose

The prevalence of peri-implant diseases, including peri-implant mucositis and peri-implantitis, is increasing. The aim of this study was to elucidate the pathological mechanisms of inflammation and alveolar bone resorption in peri-implant tissues. To do this, we fabricated inflamed gingiva around mini-implants in the palatine processes of rats using lipopolysaccharide derived from Porphyromonas gingivalis (P.g-LPS).

Materials and methods

Pure titanium mini-implants were implanted into the palatine processes of rats, and then intermittent injections of P.g-LPS were made into the gingival tissues surrounding the mini-implants. The expression patterns of tumor necrosis factor-α, interleukin-1β, chemokine (C-C motif) ligand 2, receptor activator of nuclear factor κB ligand (RANKL), and osteoprotegerin (OPG) in the tissues were examined using real-time reverse transcriptase polymerase chain reaction or enzyme-linked immunosorbent assays. Immunohistochemical analysis was also performed to compare the T and B cells expressing RANKL.

Results

P.g-LPS increased the expressions of tumor necrosis factor-α, interleukin-1β, chemokine (C-C motif) ligand 2, and RANKL in the gingival tissues surrounding the mini-implants. In contrast, the expression of OPG in the P.g-LPS samples was decreased. Consequently, the RANKL/OPG ratio was significantly increased. Moreover, cells stained positively for both anti-CD3 and anti-RANKL antibodies were only found in the samples treated with P.g-LPS.

Conclusion

These data revealed that P.g-LPS injections increased the RANKL/OPG ratio in the gingival tissues surrounding mini-implants in the rat model. In addition, the CD3-positive cells in the gingival tissues injected with P.g-LPS expressed RANKL. This suggests that the activated T cells capable of infiltrating gingival tissues affected by P.g-LPS may be one of the sources of RANKL and may also be involved in the disease progression from peri-implant mucositis to peri-implantitis.

Microbiome of peri-implant infections: lessons from conventional, molecular and metagenomic analyses

Osseointegrated dental implants are now a well-established treatment option in the armament of restorative dentistry. These technologically advanced devices are designed to functionally and esthetically replace missing teeth. Despite the revolutionary advances that implants have incurred, they have also provided the oral cavity with new artificial surfaces prone to the formation of oral biofilms, similarly to the hard tissue surfaces of natural teeth. Biofilm formation on the implant surface can trigger the inflammatory destruction of the peri-implant tissue, in what is known as peri-implantitis. The mixed microbial flora of peri-implant infections resembles that of periodontal infections, with some notable differences. These are likely to expand with the ever increasing application of metagenomics and metatrascriptomics in the analysis of oral ecology. This review presents the wealth of knowledge we have gained from microbiological methods used in the characterization of peri-implant microflora and sheds light over potential new benefits, as well as limitations, of the new sequencing technology in our understanding of peri-implant disease pathogenesis.

Oral prophylaxis and its effects on halitosis-associated and inflammatory parameters in patients with chronic periodontitis

OBJECTIVE

A controlled clinical trial was conducted to evaluate the effects of oral prophylaxis on halitosis-associated, immunological and microbiological parameters.

METHODS

Thirty subjects were included in this controlled clinical trial (patients with generalized chronic periodontitis and controls without clinical attachment loss; each n = 15). Before oral prophylaxis and 14 days after (including tongue cleaning) volatile sulphur compounds (VSC), organoleptic scores and a tongue coating index were evaluated. The levels of IL-1β, IL-8, IL-10 and MMP-8 were measured in GCF, and also major periodontal pathogens were detected. Data were statistically analysed using anova and paired t-test.

RESULTS

Supragingival plaque and calculus removal with combined tongue cleaning was able to reduce significantly (P < 0.05) the VSC values in both groups (no significant differences between both groups). Two weeks after periodontal debridement, the VSC values were observed in the periodontitis group, but not in the control group, similar to the baseline values. The difference between the groups was statistically significant (P < 0.05). Only a repeated prophylaxis session in the periodontitis group was able to reduce VSC values significantly in comparison with baseline (P < 0.05). Organoleptic scores (10 and 30 cm) were significantly different (P < 0.05) between both groups before and after the treatment. Periodontal pathogens and host-derived markers were not significantly affected by a single prophylaxis session.

CONCLUSIONS

Oral prophylaxis may result in a significant decrease in VSC values. However, in periodontal diseases, a more complex treatment seems to be necessary.

RCT comparing minimally with moderately rough implants. Part 2: microbial observations

BACKGROUND

Most current implants have a moderately rough surface (compared with older minimally rough "turned" implants) to facilitate osseointegration. This randomized controlled trial (RCT), with split-mouth design, examined whether this increased surface roughness influenced the initial subgingival plaque formation.

MATERIAL AND METHODS

Ten fully edentulous and eight partially edentulous patients, all with a history of severe periodontitis, received 4-6 implants (mandible or maxilla). Per jaw, both minimally (turned) and moderately rough (TiUnite) implants (MKIII; Nobel Biocare) were alternated. Also, the healing and final abutments had similar surface characteristics. Subgingival biofilm formation was followed up for 1 year, and samples were analyzed by culture technique, qPCR and checkerboard

RESULTS

Over the entire period, no statistically significant differences could be detected in subgingival microbiota between the minimally and moderately rough surfaces. In partially edentulous patients, the biofilm matured to a higher concentration of pathogens when compared with fully edentulous patients. The subgingival implant composition and concentration in partially edentulous patients were comparable to the subgingival microbiota along teeth.

CONCLUSION

The roughness of the more modern implants did not influence the biofilm formation during the first year of implant loading.

Early bacterial colonization and soft tissue health around zirconia and titanium abutments: an in vivo study in man

AIM

To compare the early bacterial colonization and soft tissue health of mucosa adjacent to zirconia (ZrO(2)) and titanium (Ti) abutment surfaces in vivo.

MATERIALS AND METHODS

Twenty edentulous subjects received two endosseous mandibular implants. The implants were fitted with either a ZrO(2) or a Ti abutment (non-submerged implant placement, within-subject comparison, left-right randomization). Sulcular bacterial sampling and the assessment of probing pocket depth, recession and bleeding on probing were performed at 2 weeks and 3 months post-surgery. Wilcoxon matched-pairs, sign-rank tests were applied to test differences in the counts of seven marker bacteria and the clinical parameters that were associated with the ZrO(2) and Ti abutments, at the two observation time points.

RESULTS

ZrO(2) and Ti abutments harboured similar counts of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Peptostreptococcus micros, Fusobacterium nucleatum and Treponema denticola at 2 weeks and 3 months. Healthy clinical conditions were seen around both ZrO(2) and Ti abutments at all times, without significant differences in most clinical parameters of peri-implant soft tissue health. Mean probing depths around Ti abutments were slightly deeper than around ZrO(2) abutments after 3 months (2.2 SD 0.8 mm vs. 1.7 SD 0.7 mm, P=0.03).

CONCLUSIONS

No difference in health of the soft tissues adjacent to ZrO(2) and Ti abutment surfaces or in early bacterial colonization could be demonstrated, although somewhat shallower probing depths were observed around ZrO(2) abutments after 3 month.

Effectiveness of a new toothbrush design versus a conventional tongue scraper in improving breath odor and reducing tongue microbiota

For centuries, specific instruments or regular toothbrushes have routinely been used to remove tongue biofilm and improve breath odor. Toothbrushes with a tongue scraper on the back of their head have recently been introduced to the market. The present study compared the effectiveness of a manual toothbrush with this new design, i.e., possessing a tongue scraper, and a commercial tongue scraper in improving breath odor and reducing the aerobic and anaerobic microbiota of tongue surface. The evaluations occurred at 4 moments, when the participants (n=30) had their halitosis quantified with a halimeter and scored according to a 4-point scoring system corresponding to different levels of intensity. Saliva was collected for counts of aerobic and anaerobic microorganisms. Data were analyzed statistically by Friedman's test (p<0.05). When differences were detected, the Wilcoxon test adjusted for Bonferroni correction was used for multiple comparisons (group to group). The results confirmed the importance of mechanical cleaning of the tongue, since this procedure provided an improvement in halitosis and reduction of aerobe and anaerobe counts. Regarding the evaluated methods, the toothbrush's tongue scraper and conventional tongue scraper had a similar performance in terms of breath improvement and reduction of tongue microbiota, and may be indicated as effective methods for tongue cleaning.

Subgingival and tongue microbiota during early periodontitis

Periodontal infections have a microbial etiology. Association of species with early disease would be useful in determining which microbes initiate periodontitis. We hypothesized that the microbiota of subgingival and tongue samples would differ between early periodontitis and health. A cross-sectional evaluation of 141 healthy and early periodontitis adults was performed with the use of oligonucleotide probes and PCR. Most species differed in associations with sample sites; most subgingival species were associated with subgingival samples. Few species were detected more frequently in early periodontitis by DNA probes. Porphyromonas gingivalis and Tannerella forsythia (Tannerella forsythensis) were associated with early periodontitis by direct PCR. In conclusion, the microbiota of tongue samples was less sensitive than that of subgingival samples in detecting periodontal species, and there was overlap in species detected in health and early periodontitis. Detection of periodontal pathogens in early periodontitis suggests an etiology similar to that of more advanced disease.

Tongue coating and tongue brushing: a literature review

The present paper reviews the role of the tongue as a habitat for oral microorganisms and the potential need for tongue cleaning as part of daily oral hygiene. In addition tongue coating is described. Many microorganisms have been found colonizing the dorsum of the tongue. Some studies find a positive effect to tongue brushing on bacterial counts on the tongue. On the other hand there are also studies that do not find any differences in bacterial counts before or after tongue brushing. Bacteria colonizing the tongue and periodontal pockets play an important role in the production of volatile sulphur compounds in periodontal health and disease. These compounds can be the cause of oral malodour. The amount of tongue coating in patients complaining of halitosis was significantly greater than in patients without halitosis. Tongue brushing on a regular basis, particular aiming at removing the coating on the dorsum of the tongue, has been found to be fruitful in reducing oral malodour. Studies investigating the role of tongue brushing and plaque accumulation or gingival inflammation show conflicting results. It is clear that the tongue forms the largest niche for microorganims in the oral cavity. However, on the basis of literature, there appears to be no data to justify the necessity to clean the tongue on a regular basis. One exception would be oral malodour.

Early colonization of non-submerged dental implants in patients with a history of advanced aggressive periodontitis

The aim of the study was to evaluate the early colonization of non-submerged implants over a 6-month period in partially edentulous patients treated for advanced aggressive periodontal disease. In 22 patients treated for advanced aggressive periodontitis and in a supportive maintenance program for a period between 12 and 240 months at implant surgery, a total of 68 non-submerged dental implants were installed. Patients had a plaque score below 20%, and less than 20% of the pockets around the teeth were bleeding on probing (BOP). Using DNA-probes (micro-IDent), the presence and concentration of five periodontal pathogens (Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Tannerella forsythensis (Tf) and Treponema denticola (Td)) were determined in the five deepest pockets of the rest dentition pre-operatively and after 6 months as well as five places around each implant 10 days, 1 month, 3 months and 6 months after surgery. In each patient, a test to determine the genotype interleukin-1 (IL-1) was performed (PST - micro-IDent). After 6 months, no difference in microbial composition as compared with baseline was found around the teeth in five patients, in 12 minute differences and in five patients important differences were observed. Ten days after surgery, three patients had a complete similar bacterial composition between teeth and implants. In 14 patients, the composition was fairly similar, while large differences in composition and concentration occurred in five patients. This microbiota around the implants remained almost unchanged over a 6-month period and did not hamper the clinical and radiographic osseointegration and did not lead to peri-implantitis, mucositis or initiation of bone destruction.

Dynamics of initial subgingival colonization of ‘pristine’ peri-implant pockets

BACKGROUND

Periodontitis and peri-implantitis are linked to the presence of several key pathogens. The treatment of these infectious processes therefore involves the reduction/eradication of bacteria associated with periodontitis.

METHODS

This prospective, split-mouth, single-blind study followed the colonization of 'pristine' sulci created in 42 partially edentulous patients during implant surgery (e.g. abutment connection). The hypothesis was that the composition of the maturing subgingival plaque in these 'fresh' peri-implant pockets would soon (within 2 weeks) be comparable to the subgingival microbiota of teeth with similar clinical parameters (reference sites), including the presence of bacteria associated with periodontitis. Per patient, four subgingival plaque samples were taken from shallow and medium pockets around implants (test sites), and teeth within the same quadrant (undisturbed microbiota as control sites), 1, 2, 4, 13, 26 and 78 weeks after abutment connection, respectively. The samples were analysed by either checkerboard DNA-DNA hybridization, or cultural techniques, or real-time polymerase chain reaction (PCR) for intra-subject comparisons (teeth vs. implant, for comparable probing depths).

RESULTS

Checkerboard DNA-DNA hybridization and real-time PCR revealed a complex microbiota (including several pathogenic species) in the peri-implant pockets within 2 weeks after abutment connection. After 7 days, the detection frequency for most species (including the bacteria associated with periodontitis) was already nearly identical in samples from the fresh peri-implant pockets (5% and 20% of the microbiota belonging to red and orange complex, respectively) when compared with samples from the reference teeth. Afterwards (e.g. between weeks 2 and 13), the number of bacteria in peri-implant pockets only slightly increased (+/-0.1 log value), with minor changes in the relative proportions of bacteria associated with periodontitis (8% and 33% of the microbiota belonging to red and orange complex, respectively). Although small differences were seen between teeth and implants at week 2 with cultural techniques, a striking similarity in subgingival microbiota was found with this technique from month 3 on, with nearly identical detection frequencies for bacteria associated with periodontitis for both abutment types.

CONCLUSIONS

This study indicates that the initial colonization of peri-implant pockets with bacteria associated with periodontitis occurs within 2 weeks.

Distribution of selected bacterial species on intraoral surfaces

BACKGROUND/AIM

To examine the proportions of 40 bacterial species in samples from 8 oral soft tissue surfaces and saliva in systemically healthy adult subjects and to compare these microbiotas with those of supra- and subgingival plaque.

METHODS

Microbial samples were taken from 8 oral soft tissue surfaces of 225 systemically healthy subjects using a "buccal brush". Saliva was taken by expectoration. Forty-four of these subjects provided additional supra- and subgingival plaque samples. Samples were individually evaluated for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. The percentage of total DNA probe count was determined for each species, at each sample location and averaged across subjects. The significance of differences among the proportions of the 40 test species at different sample locations was sought in the 225 and 44 subjects separately using the Quade test and adjusted for multiple comparisons. Cluster analysis was performed using the proportions of the 40 species at the different sample locations using the minimum similarity coefficient and an average unweighted linkage sort. The proportions of each species were averaged across subjects in the resulting cluster groups and the significance of differences was tested using the t-test and ANOVA.

RESULTS

Microbial profiles differed markedly among sample locations in the 225 subjects, with 34 of 40 species differing significantly. Proportions of Veillonella parvula and Prevotella melaninogenica were higher in saliva and on the lateral and dorsal surfaces of the tongue, while Streptococcus mitis and S. oralis were in significantly lower proportions in saliva and on the tongue dorsum. Cluster analysis resulted in the formation of 2 clusters with >85% similarity. Cluster 1 comprised saliva, lateral and dorsal tongue surfaces, while Cluster 2 comprised the remaining soft tissue locations. V. parvula, P. melaninogenica, Eikenella corrodens, Neisseria mucosa, Actinomyces odontolyticus, Fusobacterium periodonticum, F. nucleatum ss vincentii and Porphyromonas gingivalis were in significantly higher proportions in Cluster 1 and S. mitis, S. oralis and S. noxia were significantly higher in Cluster 2. These findings were confirmed using data from the 44 subjects providing plaque samples. The microbial profiles of supra- and subgingival plaque differed from the other sample locations, particularly in the increased proportions of the Actinomyces species. Species of different genera exhibited different proportions on the various intraoral surfaces, but even within the genus Streptococcus, there were differences in colonization patterns. S. oralis, S. mitis and S. constellatus colonized the soft tissues and saliva in higher proportions than the samples from the teeth, while the other 4 streptococcal species examined colonized the dental surfaces in proportions comparable to the soft tissue locations and saliva.

CONCLUSIONS

Proportions of bacterial species differed markedly on different intraoral surfaces. The microbiota of saliva was most similar to that of the dorsal and lateral surfaces of the tongue. The microbiotas of the soft tissues resembled each other more than the microbiotas that colonized the teeth both above and below the gingival margin.

Similarity of the oral microbiota of pre-school children with that of their caregivers in a population-based study

This study evaluated the similarity between the oral microbiota of young children and that of their adult caregivers. Oral samples from children (174 dentate and 18 pre-dentate) aged 6-36 months and their caregivers in Saipan were assayed using a DNA probe assay. Many species including Streptococcus mutans, Streptococcus sobrinus, Actinomyces species, Campylobacter rectus, Fusobacterium nucleatum, Prevotella intermedia, and Porphyromonas gingivalis were detected in dentate and pre-dentate children, whereas Bacteroides forsythus was detected only in dentate children. A higher percentage of children were positive for the detection of an individual species if the caregiver was also positive. There were significant relative risks of species detection between dentate children and their caregivers. By logistic regression, there were significant positive associations between species detection in caregiver and in child, but not between species detection and child age or maternal education level. In conclusion, dental pathogens were detected in young, including pre-dentate, children. The microbial profiles of children were strongly associated with the microbiota of their caregivers.

Conventional and early loading of unsplinted ITI implants supporting mandibular overdentures

The aim of this study was to compare the success rates after 1 and 2 years of conventionally and early loaded pairs of unsplinted ITI implants supporting mandibular overdentures in edentulous patients. Twenty-four participants (age range 55-80 years) were randomly allocated with maximum concealment to two treatment groups. In the first group, the implants were allowed to heal for 12 weeks before being functionally loaded (control) and the second group had 6 weeks of healing with identical loading. All participants had new conventional complete maxillary and mandibular dentures prior to the study. Two sandblasted large-grit acid-etched (SLA) surface ITI implants were placed in the mandibular interforaminal area, following a standardized nonsubmerged surgical protocol. After 6 or 12 weeks of healing, matrices were processed into the fitting surface of the pre-existing mandibular dentures and the implants loaded. Implant success was determined using mobility tests and radiographs taken at baseline and 52 and 104 weeks after surgery. Clinical peri-implant parameters were also documented. Results showed all implants successfully osseointegrated, according to accepted criteria, after 2 years. Mean loss of crestal bone height after 1 year was 0.35 +/- 0.22 mm (control) vs. 0.27 +/- 0.18 mm (test). After 2 years this reduced to 0.09 +/- 0.06 mm (control) vs. 0.12 +/- 0.17 mm (test). The mean Periotest value after 1 year was -4.9 (control) vs.-3.78 (test). After 2 years, the mean resonance frequency value for the control implants was 6797 Hz [mean implant stability quotient (ISQ) = 64.77] and for the test implants 6670 Hz (mean ISQ = 62.0). Shortened loading periods for these ITI implants did not cause any statistically significant differences in osseointegration or peri-implant parameters. We conclude that pairs of unsplinted SLA-surface ITI implants can be successfully loaded with mandibular overdentures 6 weeks after surgery.

Role of Treponema denticola in periodontal diseases

Among periodontal anaerobic pathogens, the oral spirochetes, and especially Treponema denticola, have been associated with periodontal diseases such as early-onset periodontitis, necrotizing ulcerative gingivitis, and acute pericoronitis. Basic research as well as clinical evidence suggest that the prevalence of T denticola, together with other proteolytic gram-negative bacteria in high numbers in periodontal pockets, may play an important role in the progression of periodontal disease. The accumulation of these bacteria and their products in the pocket may render the surface lining periodontal cells highly susceptible to lysis and damage. T. denticola has been shown to adhere to fibroblasts and epithelial cells, as well as to extracellular matrix components present in periodontal tissues, and to produce several deleterious factors that may contribute to the virulence of the bacteria. These bacterial components include outer-sheath-associated peptidases, chymotrypsin-like and trypsin-like proteinases, hemolytic and hemagglutinating activities, adhesins that bind to matrix proteins and cells, and an outer-sheath protein with pore-forming properties. The effects of T. denticola whole cells and their products on a variety of host mucosal and immunological cells has been studied extensively (Fig. 1). The clinical data regarding the presence of T. denticola in periodontal health and disease, together with the basic research results involving the role of T. denticola factors and products in relation to periodontal diseases, are reviewed and discussed in this article.

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.

Periodontal pathogen detection in gingiva/tooth and tongue flora samples from 18- to 48-month-old children and periodontal status of their mothers

Few studies have detected periodontal pathogens in young children, and when detected the prevalence has been relatively low. In this epidemiological study, we determined the prevalence of periodontal pathogen colonization in young children and examined the relationship between periodontitis in mothers and detection of periodontal pathogens in their children aged 18-48 months. Children were selected and enrolled randomly into the study; tongue and gingival/tooth plaque samples were harvested and analyzed by DNA probe checkerboard assay for Porphyromonas gingivalis and Bacteroides forsythus. Clinical measurements included a gingival bleeding score in the children and a periodontal screening and recording (PSR) score in the mothers. Mothers having one or more periodontal sites with probing depths > 5.5 mm were classified as having periodontitis. In this population, 71% (66/93) of the 18- to 48-month-old children were infected with at least one periodontal pathogen. Detection rates for children were 68.8% for P. gingivalis and 29.0% for B. forsythus. About 13.8% (11/80) of children had gingival bleeding in response to a toothpick inserted interproximally. Children in whom B. forsythus was detected were about 6 times more likely to have gingival bleeding than other children. There was no relationship between bleeding and detection of P. gingivalis. 17.0% (16/94) of the mothers had periodontitis. When all mother-child pairs were considered, the periodontal status of the mother was found not to be a determinant for detection of periodontal pathogens in the floral samples from the children. However, the odds ratio that a daughter of a mother with periodontitis would be colonized was 5.2 for B. forsythus. A much higher proportion of children in this population were colonized by P. gingivalis and/or B. forsythus than has been previously reported for other populations. A modest level of association between manifestations of periodontitis in mothers and detection of B. forsythus in their daughters was observed.

Infectious risks for oral implants: a review of the literature

The use of oral implants in the rehabilitation of partially and fully edentulous patients is widely accepted even though failures do occur. The chance for implants to integrate can for example be jeopardised by the intra-oral presence of bacteria and concomitant inflammatory reactions. The longevity of osseointegrated implants can be compromised by occlusal overload and/or plaque-induced peri-implantitis, depending on the implant geometry and surface characteristics. Animal studies, cross-sectional and longitudinal observations in man, as well as association studies indicate that peri-implantitis is characterised by a microbiota comparable to that of periodontitis (high proportion of anaerobic Gram-negative rods, motile organisms and spirochetes), but this does not necessarily prove a causal relationship. However, in order to prevent such a bacterial shift, the following measures can be considered: periodontal health in the remaining dentition (to prevent bacterial translocation), the avoidance of deepened peri-implant pockets, and the use of a relatively smooth abutment and implant surface. Finally, periodontitis enhancing factors such as smoking and poor oral hygiene also increase the risk for peri-implantitis. Whether the susceptibility for periodontitis is related to that for peri-implantitis may vary according to the implant type and especially its surface topography.

The microbiota of young children from tooth and tongue samples

This study determined the frequency with which 38 microbial species were detected in 171 randomly selected children from 6 to 36 months of age. Children were sampled and dental caries measured. Oral samples were assayed by means of a checkerboard DNA probe assay. The detection frequencies from tongue samples in children under 18 mos were: S. mutans 70%, S. sobrinus 72%, P. gingivalis 23%, B. forsythus 11%, and A. actinomycetemcomitans 30%, with similar detection frequencies in children over 18 mos. Thus, S. mutans and the periodontal pathogens, P. gingivalis and B. forsythus, were detected even in the youngest subjects. Species associated with caries included S. mutans (children ages 18-36 mos) and A. israelii (children ages < 18 mos), the latter species possibly reflecting increased plaque in children with caries. Species detection from tooth and tongue samples was highly associated, with most species detected more frequently from tongue than from tooth samples in children under 18 mos, suggesting that the tongue was a potential microbial reservoir.

Tongue coating and salivary bacterial counts in healthy/gingivitis subjects and periodontitis patients

BACKGROUND

The papillary structure of the dorsum of the tongue forms a unique ecological site that provides a large surface area favoring the accumulation of oral debris and microorganisms. These micro-organisms of the tongue may be of influence on the flora of the entire oral cavity. The normal appearance of the dorsum of the tongue is either pinkish or has a thin white coating. For the present study a scoring method was developed to describe the appearance of the dorsum of the tongue in relation to the extent of color and thickness of tongue coating.

AIM

The purpose of this study was to investigate the discoloration and coating of the tongue in healthy/gingivitis subjects and periodontitis patients. Furthermore, to determine the relationship between the appearance of the tongue and the bacterial load in salivary samples.

MATERIAL AND METHODS

2 groups of patients were studied, 70 healthy/gingivitis subjects and 56 periodontitis patients. After scoring of the tongue a salivary sample of each patient was taken and analyzed using a phase-contrast microscope.

RESULTS

This investigation showed that most discoloration was found on the distal part of the tongue. The mean number of bacteria per ml sample in relation to a pink, white and yellow appearance of the tongue was 948, 855 and 900 (x 10(6)) respectively. The mean number of bacteria per ml sample in relation to no, thin and thick coating was 948, 863, and 895 (x 10(6)), respectively. Analysis did not reveal a relationship between discoloration, coating thickness and total bacterial load. The mean number of bacteria per ml in healthy/gingivitis subjects was 860 and in periodontitis patients 918 (x 10(6)).

CONCLUSION

No relationship between the appearance of the tongue and salivary bacterial load could be detected. There was no difference in bacterial load between the healthy/gingivitis and the periodontitis group within the present study population.