[Effect of periodontal surgery on the subgingival periodontal microbiota in artificial class III furcation defects: an experimental study in monkeys]

OBJECTIVE

This study was to longitudinally evaluate the change of prevalence of five periodontal putative pathogens in the subgingival plaque of artificial class III furcation defects at the three time-points, including before the establishment of furcation defects, before and 6 months after periodontal surgery.

METHODS

Eighteen chronic infected class III FI defects were created at the mandibular first molars, second molars and second premolars of three adult male Macaca fascicularis. The samples of subgingival plaque were obtained from the subgingival area of furcation defects in buccal and lingual sites before the establishment of furcation defects, before and 6 months after periodontal surgery. 36 samples were obtained at one time-points. Five periodontal putative pathogens, including Porphyromonas gingivalis (Pg), Tannerella forsythensis (Tf), Treponema dinticola (Td), Actinobacillus actinomycetemcomitans (Aa) and Fusobacterium nucleatum (Fn), were detected with 16SrRNA based PCR.

RESULTS

1. The prevalence of Pg, Tf, Td and Fn was gradually increased, from 58.3% to 69.4% to 88.9%, 47,2% to 69.4% to 83.3%, 13.9% to 36.1% to 61.1% (P<0.01), and 69.4% to 91.7% to 91.7% (P<0.05), respectively during the experimental period. The prevalence of Fn was higher than Pg, Tf and Td. The prevalence of Aa was the lowest and no obvious difference among the three samplings(from 25.9% to 13.9% to 33.3%)was detected. 2. The prevalence of more than 3 species simultaneously detected was increased from 38.9% to 61.1% to 83.3% (P <0.01). The red complex (Pg + Tf + Td) was detected from 8.3% to 27.8% to 44.4% (P<0.01) at the different time point. 3. The combined detection frequency of red complex in the inflammatory sites (87.5%), which were histologically defined as inflammatory cells infiltrated in furcation area 6 months post-surgery, and the same sites pre-surgery (62.5%) was more than that in pre-creation of furcation defects (P<0.01). But there were no significant differences compared to that in non inflammatory area (60.0%, 40.0%), respectively.

CONCLUSION

The prevalence of periodontal pathogenic bacteria correlated with the severity of local inflammation. The increase of coexistent rate of red complex at the second and third sampling times suggests that the red complex play important role in the pathogenesis of periodontitis. Fn may be a resident bacteria in the subgingival plaque, play a bridge role on the biofilm formation and maturation. Aa may not be a major causative bacteria in the clinical periodontitis.

Effect of two different approaches for root decontamination on new cementum formation following guided tissue regeneration: a histomorphometric study in dogs

BACKGROUND AND OBJECTIVE

The aim of the present study was to evaluate comparatively the effect of two different approaches for root decontamination on new cementum formation following guided tissue regeneration (GTR).

MATERIAL AND METHODS

Nine mongrel dogs were used to obtain bilateral chronic class III furcation defects by placing cotton ligatures around both third mandibular premolars. The teeth were randomly assigned to receive one of the following treatments: scaling and root planing, by means of hand and rotatory instruments, in order to remove soft and hard deposits as well as all root cementum (group A); or removal of only soft microbial deposits, by polishing the root surface with rubber cups and polishing paste, aiming for maximum root cementum preservation (group B). Both groups were treated with GTR, with the use of resorbable polyglycolic-lactic acid membranes (RESOLUT XT).

RESULTS

Four months later, data analysis showed that a superior length (mm) (3.59 +/- 1.67 and 6.20 +/- 2.26 for groups A and B, respectively; p = 0.004) and a thicker layer (microm) (18.89 +/- 9.47 and 52.29 +/- 22.48 for groups A and B, respectively; p = 0.001) of new cementum was achieved by keeping the root cementum in place during root decontamination (group B). Regardless of the treatment modality, the new cementum was predominantly of a reparative, cellular extrinsic and intrinsic fiber type.

CONCLUSION

Within the limits of the present study, it may be concluded that root cementum preservation may affect the new cementum formation following GTR in class III furcation defects, and the treatment modality did not influence the type of newly formed cementum.

Systemic release of endotoxins induced by gentle mastication: association with periodontitis severity

BACKGROUND

Periodontitis has recently been identified as a potential risk factor for systemic pathologies such as cardiovascular disease, the hypothesis being that periodontal pockets could release pro-inflammatory bacterial components, for instance endotoxins, into the bloodstream. It is known that the oral cavity can be a source of circulating bacteria, but this has never been shown for bacterial endotoxins, and no evidence exists so far that the risk of systemic injury is related to the severity of periodontitis. The aim of the present study was to test the influence of gentle mastication on the occurrence of endotoxemia in patients with or without periodontal disease.

METHODS

A total of 67 subjects were periodontally examined and grouped according to their periodontal status. This classification was based on an original index of severity of periodontal disease (periodontal index for risk of infectiousness, PIRI) aimed at reflecting the individual risk of systemic injury from the periodontal niches. Thus, the patients were classified into 3 risk groups: low, PIRI = 0; n = 25; moderate, 1 < or = PIRI < or = 5, n = 27; and high 6 < or = PIRI < or = 10, n = 15. Blood samples were collected before and 5 to 10 minutes after a standardized session of gentle mastication for detection of circulating endotoxins. Blood samples were tested with a chromogenic limulus amoebocyte lysate assay.

RESULTS

Overall, blood levels of endotoxin after mastication were found to be significantly higher than before mastication (0.89 +/- 3.3 pg/ml versus 3.0 +/- 5.8 pg/ml; P= 0.0002). Likewise, the incidence of positive endotoxemia rose from 6% before mastication to 24% after mastication (P = 0.001). When accounting for the PIRI index, endotoxin levels and positive endotoxemia proved to be significantly higher in patients with severe periodontal disease than in the subjects with low or moderate periodontitis.

CONCLUSIONS

Gentle mastication is able to induce the release of bacterial endotoxins from oral origin into the bloodstream, especially when patients have severe periodontal disease. This finding suggests that a diseased periodontium can be a major and underestimated source of chronic, or even permanent, release of bacterial pro-inflammatory components into the bloodstream.

The influence of sulfate-reducing bacteria colonization of 2 different bioresorbable barrier membranes for GTR. An 18-month case-controlled microbiologic and clinical study

The purpose of the present microbiologic and case-controlled clinical study was to examine the colonization of 2 different resorbable barrier membranes by sulfate-reducing bacteria (SRB). The barrier membranes tested were Guidor matrix barrier and Resolut regenerative material. Ten patients exhibiting 3 Class II furcation defects and 7 intrabony defects were included in the study. The probing depth and the clinical attachment level at 4 surfaces per tooth were taken at the beginning of the study. Microbiologic samples were taken from the experimental sites and from the approximal sites of the adjacent teeth. Both types of resorbable membranes were positive for SRB colonization. The detection of SRB in 2 of 7 intrabony defects and in all defects with furcation involvement before the membrane placement indicated that these organisms are a common inhabitant of sites showing periodontal destruction and are associated with guided tissue regeneration (GTR). According to the clinical criteria for healing tendencies used in this study, the GTR procedures were less successful in the presence of SRB. There were no significant clinical effects of different resorbable membrane materials or membrane layout on attachment level changes for either the intrabony defect or furcation groups after 18 months. There were no statistical differences for sites that became exposed to SRB when compared to sites that remained unexposed after 18 months. The numeric significance of SRB in relation to the total microbial count needs to be determined to gain insight into the ecologic role of membrane resorption rates.

Semi-automated measurement of motility of human subgingival microflora by image analysis

The purpose of this investigation was to quantitatively estimate bacterial motility by image analysis, and to apply this method for the measurement of motility of human subgingival microflora. We developed a semi-automated method for the quantification of bacterial motility using video microscopy, digitization and image processing. Moving images of both authentic bacterial samples and clinical samples were recorded using a phase contrast microscope with a high speed (1/100 s) shutter camera. The motility was evaluated by measuring the total number of pixels remaining after the subtraction of 2 serial video images. The total number of pixels was significantly correlated with both the sum of the velocity of each bacterial cell and the number of motile bacteria on the same original images. Motility of subgingival microflora from 140 clinical samples tested was measured at 0 pixels to 3600 pixels, whereas the effect of Brownian movement was less than 150 pixels. The motility of subgingival microflora estimated with this image analysis system did not differ much from objective judgments by the naked eyes of experts. These results suggest that a semi-automated image analysis system may be useful in the evaluation of the motility of human subgingival microflora.

The effect of an absorbable collagen membrane on the subgingival microflora

The purpose of this study was to determine the effect of use of an absorbable collagen membrane in guided tissue regeneration (GTR) therapy upon the subgingival microflora. The study group consisted of 12 systemically healthy patients with bilateral mandibular furcation defects with attachment loss > or = 6 mm; one site was randomly assigned for GTR treatment while the contralateral site received surgical flap debridement only. Subgingival plaque samples were collected by paper point on the day of surgery and at 2, 4 and 6 months post-surgery. Three sites were sampled in each patient: a collagen membrane site, a control surgical site, and an unoperated control site. Plaque samples were transported in a non-phosphated buffer solution and examined by phase-contrast microscopy. Cocci, rods, spirochetes, fusiforms, curved rods, and total bacteria were recorded per 10 high-power fields. Following statistical analysis utilizing the Bonferroni (Dunn) t test, no differences in total bacterial counts were found among the sites at any of the time intervals examined. Total bacterial counts were found lower at both the collagen membrane and control surgical sites post-surgery as compared to unoperated control sites, but these differences were not statistically significant (P > .05). In addition, no significant differences were detected in bacterial profiles between sites or individual time points. Results from this 6-month limited clinical trial suggest that the placement of an absorbable collagen membrane as part of a standard surgical regimen for GTR therapy does not alter the local microflora.

Perforation repair comparing mineral trioxide aggregate and amalgam using an anaerobic bacterial leakage model

The purpose of this study was to evaluate the ability of mineral trioxide aggregate (MTA) and amalgam to seal furcal perforations in extracted human molars using an anaerobic bacterial leakage model. Furcal perforations were made in 39 maxillary and mandibular human molars with a high-speed bur. These were randomly divided into two experimental groups of 18, with the remaining three teeth used as positive controls. Experimental group 1 was repaired with MTA and group 2 with amalgam. Three additional teeth without perforations served as negative controls. A dual chamber anaerobic bacterial leakage model was assembled. Brain heart infusion broth with yeast extract, hemin, menadione, and the chromogenic indicator bromcresol purple was used as the culture broth for Fusobacterium nucleatum. Eight of 18 amalgam samples leaked, whereas none of the 18 MTA samples leaked. MTA was significantly better than amalgam in preventing leakage of F. nucleatum past furcal perforation repairs.

The effect of supragingival plaque control on the subgingival microflora in human periodontitis

The aim of the present trial was to study if carefully practiced supragingival plaque control influenced the subgingival microbiota at periodontal sites with suprabony, infrabony, or furcation pockets. 12 subjects, 5 males and 7 females aged 44 to 69 years (mean age 55 years) participated in the study. None of the participants had during the last 12 months received periodontal therapy, and none of the subjects had used antibiotics during a 3-month period preceding the study. Following a screening examination, 6 to 8 sites per subject were selected which had a probing depth of > or = 5 mm. Among these sites, 1-3 sites had a suprabony location, 1-3 sites had an infrabony location, and 1-3 sites were associated with a furcation defect. The selected sites were exposed to a baseline examination at which the following parameters were recorded: plaque, gingivitis, probing pocket depth and probing attachment level. A bacterial sample was obtained from each of the selected sites: 2 sterile paper points were inserted into the pocket and kept in place for 30 seconds. The paper point samples were removed, placed in a vial containing an anaerobically prepared transport medium, and processed using routine procedures. Following the baseline examination, each subject was given a case presentation, received thorough supragingival scaling and was instructed to practice proper plaque control with the use of toothbrush and dentifrice. During the subsequent 30 weeks they were recalled 2-3xper week for professional tooth cleaning. Each session was handled by a dental hygienist and required about 15 min. Re-examinations were performed after 30 weeks. The findings indicated that professionally delivered and frequently repeated supragingival tooth cleaning, combined with careful self-performed plaque control had a marked effect on the subgingival microbiota of moderate to deep periodontal pockets. Thus, at sites with suprabony and infrabony pockets, as well as at furcation sites, the meticulous and prolonged supragingival plaque removal reduced the total number of microorganisms that could be harvested, as well as the % of sites with P. gingivalis.

Long-term stability of Class II furcation defects treated with barrier membranes

The present longitudinal study was designed to explore the long-term efficacy of guided tissue regeneration (GTR) in Class II furcation defects and establish the factors that might be responsible for modifying this response. Subjects with two or more mandibular molars, one of which had Class II furcation defects, received the hygienic phase of therapy followed by baseline clinical measurements and subgingival plaque sampling. GTR procedure was performed in furcation defect sites using expanded polytetrafluoroethylene (ePTFE) membranes, while the other non-furcated molars received only scaling and root planning. Twenty-eight subjects (13 females, 15 males) aged 27 to 66 were included in this longitudinal analysis. Post-surgical treatment included routine home care supplemented with daily chlohexidine rinse and systemic tetracycline. Membranes were retrieved 4 to 6 weeks after surgery. During the first year, patients were initially seen bi-weekly and subsequently monthly for professional prophylaxis. At the end of this year, clinical measurements and samples were obtained. For the next 2 years, patients were seen bi-annually for maintenance visits. Clinical measurements and microbiological samples were then repeated. Next, a tighter maintenance protocol was established and patients were seen quarterly for scaling and oral hygiene reinforcement. Final measurements and samples were taken again 1 year later (4 years postoperative). Significant probing reduction (3.00 mm) and gain in horizontal attachment (2.59 mm) were obtained 1 year postsurgery for the GTR sites. These changes were maintained over 4 years with a slight decline at the end of year 3. Changes in probing depth (PD) from year 1 to 4 served to dichotomize the sites into stable (delta PD < or = 0.9 mm), and unstable (PD increase > or = 1 mm). Of the 54 sites available for this analysis only 5 (9.3%) were unstable while 49 (90.7%) were stable or even further improved. Sites which exhibited minimal or no plaque (plaque index [PI] < or = 1) over the tight maintenance period had a further decrease in mean probing depth (0.43 mm) compared with a slight increase (-0.06 mm) in mean probing depth in sites with PI > or = 2 mm (P = 0.0235). The same phenomenon was observed for changes in relative attachment level (RAL): mean gain in RAL was 0.61 mm compared to 0.25 mm for the 2 groups, respectively (P = 0.07). Actinobacillus actinomycetemcomitans was only isolated from 2 sites at year 3, and none at year 4, compared to 21.45% of the sites at baseline. Porphyromonas gingivalis positive sites showed a continual decline over the years: 14.28% at baseline, 10.71% at year 1, and 5.1% at year 4. On the contrary, Prevotella intermedia (Pi) and Bacteroides forsythus (Bf) infected sites remained at approximately the same rate throughout the 4 years of the study (40% to 50% and 30% to 40% for Pi and Bf, respectively). Of these, Pi-infected sites exhibited less favorable clinical results compared to sites which were not infected with this microorganism. In summary, furcation defects treated with membrane barriers can be maintained in health for at least 4 years; however, good oral hygiene and frequent recall visits as part of a complete anti-infective therapy are essential. Finally, once treated, these teeth are comparable to similar molar teeth with no previous history of furcation pathosis.

Systemic antimicrobial treatment and guided tissue regeneration. Clinical and microbiological effects in furcation defects

The purpose of this investigation was to study the microbiota associated with furcation-involved teeth before and after treatment by the guided tissue regeneration procedure (GTR) with non-resorbable ePTFE membranes, and to evaluate the benefit of additional systemic antimicrobial therapy (ornidazole). Each of 10 patients contributed 1 pair of bilateral mandibular molars with comparable furcation defects. 5 defects were treated with a membrane and the active drug, 5 were treated without a membrane but with the active drug, 5 were treated with a membrane and a placebo, and 5 were treated with neither a membrane nor the active drug. Considerable differences were found in the healing response of furcation defects treated with or without the antimicrobial agent. More horizontal attachment gain and increase in bone density was obtained in patients receiving the active drug than in patients receiving the placebo. With 1 exception, all sites with increasing horizontal probing depth were found in patients of the placebo group. Treatment with membrane plus ornidazole resulted in 0.7 mm mean recession and -1.2 mm mean decrease in horizontal probing depth. Sites treated with membranes generally tended to be positive for 15 target micro-organisms more often than sites treated without a membrane. This was particularly evident for Fusobacterium, Prevotella intermedia and Actinomyces odontolyticus. Whereas GTR-treated sites were often already positive upon removal of the membrane, re-emergence of target organisms seemed to be more delayed in the conventionally-treated sites.

Clinical, microbiological, and histological factors which influence the success of regenerative periodontal therapy

The primary objectives of this double-blind, controlled clinical trial were to assess factor(s) which affect the success of guided tissue regeneration (GTR) procedures in mandibular Class II buccal furcation defects. Thirty subjects, with mandibular Class II furcation defects, were randomly assigned to one of two treatment groups; patients in Group A received oral hygiene instructions with scaling and root planing, while subjects in Group B received similar treatment but without subgingival scaling and root planing at the affected site. After initial oral hygiene instructions and scaling and root planing, GTR surgery was performed using ePTFE barrier membranes. Membranes were retrieved at 6 weeks and subjected to histological examination. Twelve months after regenerative therapy, clinical measurements and re-entry surgical measurements were repeated. Probing reduction (2.61 mm), horizontal probing attachment gain (2.59 mm), and vertical probing attachment gain (0.95 mm) were all significantly better compared to baseline. Likewise, significant improvements in furcation volume (8.0 microliters) and in bone measurements were observed at re-entry. There was no discernible difference between subjects for whom complete anti-infective therapy was deferred to the time of the surgery (Group B) compared to subjects in whom complete anti-infective therapy was performed as part of the hygienic phase of therapy (Group A). Pre-operative pocket depth was directly correlated with the magnitude of attachment gain as well as the amount of new bone formation in the furcation area. Subjects who maintained good oral hygiene and who had minimal gingival inflammation throughout the study demonstrated consistently better regenerative response.(ABSTRACT TRUNCATED AT 250 WORDS)