Effect of Periodontal Treatment on Reducing Chronic Inflammation in Systemically Healthy Patients With Periodontal Disease.

BACKGROUND: We determined the effects and an accurate marker of periodontal treatment on serum interleukin (IL)-6 and high-sensitivity C-reactive protein (HsCRP) levels in systemically healthy individuals with periodontal disease. METHODS: This multicenter study included systemically healthy individuals with periodontal disease who received initial periodontal treatment and had no periodontal treatment history. Periodontal parameters, including periodontal inflamed surface area, masticatory efficiency, and periodontal disease classification; serum IL-6 and HsCRP levels; and serum immunoglobulin (Ig)G titers against periodontal pathogens were evaluated at baseline and after treatment. Subjects were classified as low or high responders (group) based on periodontal inflamed surface area changes. RESULTS: There were 153 participants. Only periodontal inflamed surface area changes were markedly different between low and high responders. Periodontal treatment (time point) decreased both serum IL-6 and HsCRP levels. The interaction between group and time point was remarkable only for serum IL-6 levels. Changes in serum immunoglobulin (Ig)G titers against periodontal pathogens were not associated with IL-6 changes in high responders. We analyzed the indirect effect of serum anti-Porphyromonas gingivalis type 2 IgG titer changes using mediation analysis and found no significance. However, the direct effect of group (low or high responder) on IL-6 changes was considerable. CONCLUSIONS: Periodontal treatment effectively decreased serum IL-6 levels, independent of periodontal pathogen infection, in systemically healthy individuals with periodontal disease.

Utility of a haemoglobin test of gingival crevicular fluid: A multicentre, observational study.

OBJECTIVE: The purpose of this study was to verify the accuracy and utility of clinical parameters (plaque index, gingival crevicular fluid volume, probing depth, clinical attachment level, bleeding on probing and gingival index) and biochemical parameters (aspartate aminotransferase, protein and haemoglobin) in a longitudinal analysis during the supportive periodontal therapy period. SUBJECTS AND METHODS: A total of 279 test sites of 128 patients were investigated clinically and biochemically. After the first examination of clinical and biochemical parameters, periodontal support treatments were administered immediately and performed once every three months up to the second examination. RESULTS: All of the clinical and biochemical parameters were significantly lower at the second examination than at the first, except for the plaque index and bleeding on probing. Of these parameters, in particular, aspartate aminotransferase and haemoglobin in the gingival crevicular fluid were significantly reduced compared to those of the first examination in both the ≤4 and ≥5 mm probing depth groups, and they clearly suggested that periodontitis tended to recover. CONCLUSION: Adding the haemoglobin test to the bleeding on probing test strongly improves the accuracy of measurement of clinical parameters after periodontal treatment.

Differences in periodontal parameters between SPT patients who regularly and irregularly visited the dental clinic analyzed at tooth level: a 14-year retrospective cohort study.

The purpose of this study was to evaluate the periodontal status of patients who routinely did SPT, when compared to patients that did not SPT. This retrospective cohort study was conducted at a general dental office from 2001 to 2019. Patients aged 18 to 81 years who visited the dental office over a 10-year period were assigned into two groups: an SPT group, which included patients who continually visited the dental office for SPT one or more times every year, and an irregular group, consisting of patients who did not visit the dental office at least once a year. A total of 7307 teeth (SPT group) and 4659 teeth (irregular group) were evaluated, and the periodontal conditions were compared between the first and latest visits. Multiple regression analysis was used to analyze the results. The mean follow-up time was 13.74 years. The risk factors for improvements in probing pocket depth included age, sex, smoking, diabetes mellitus, molar tooth, and irregular SPT group (p < 0.001), and that for a positive bleeding on probing site was the irregular group (odds ratio 2.94; 95% confidence interval 2.63-3.29). This study showed that lack of routine in attending the SPT program significantly decreased the periodontal parameters, thus highlighting the importance of continuing with the program to maintain the periodontal health.

Periodontal disease-related nonalcoholic fatty liver disease and nonalcoholic steatohepatitis: An emerging concept of oral-liver axis.

Periodontal disease, a chronic inflammatory disease of the periodontal tissues, is not only a major cause of tooth loss, but it is also known to exacerbate/be associated with various metabolic disorders, such as obesity, diabetes, dyslipidemia, and cardiovascular disease. Recently, growing evidence has suggested that periodontal disease has adverse effects on the pathophysiology of liver disease. In particular, nonalcoholic fatty liver disease, a hepatic manifestation of metabolic syndrome, has been associated with periodontal disease. Nonalcoholic fatty liver disease is characterized by hepatic fat deposition in the absence of a habitual drinking history, viral infections, or autoimmune diseases. A subset of nonalcoholic fatty liver diseases can develop into more severe and progressive forms, namely nonalcoholic steatohepatitis. The latter can lead to cirrhosis and hepatocellular carcinoma, which are end-stage liver diseases. Extensive research has provided plausible mechanisms to explain how periodontal disease can negatively affect nonalcoholic fatty liver disease and nonalcoholic steatohepatitis, namely via hematogenous or enteral routes. During periodontitis, the liver is under constant exposure to various pathogenic factors that diffuse systemically from the oral cavity, such as bacteria and their by-products, inflammatory cytokines, and reactive oxygen species, and these can be involved in disease promotion of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis. Also, gut microbiome dysbiosis induced by enteral translocation of periodontopathic bacteria may impair gut wall barrier function and promote the transfer of hepatotoxins and enterobacteria to the liver through the enterohepatic circulation. Moreover, in a population with metabolic syndrome, the interaction between periodontitis and systemic conditions related to insulin resistance further strengthens the association with nonalcoholic fatty liver disease. However, most of the pathologic links between periodontitis and nonalcoholic fatty liver disease in humans are provided by epidemiologic observational studies, with the causal relationship not yet being established. Several systematic and meta-analysis studies also show conflicting results. In addition, the effect of periodontal treatment on nonalcoholic fatty liver disease has hardly been studied. Despite these limitations, the global burden of periodontal disease combined with the recent nonalcoholic fatty liver disease epidemic has important clinical and public health implications. Emerging evidence suggests an association between periodontal disease and liver diseases, and thus we propose the term periodontal disease-related nonalcoholic fatty liver disease or periodontal disease-related nonalcoholic steatohepatitis. Continued efforts in this area will pave the way for new diagnostic and therapeutic approaches based on a periodontologic viewpoint to address this life-threatening liver disease.

Prospective Longitudinal Changes in the Periodontal Inflamed Surface Area Following Active Periodontal Treatment for Chronic Periodontitis.

Periodontal disease is a chronic inflammatory disease of the periodontal tissue. The periodontal inflamed surface area (PISA) is a proposed index for quantifying the inflammatory burden resulting from periodontitis lesions. This study aimed to investigate longitudinal changes in the periodontal status as evaluated by the PISA following the active periodontal treatment. To elucidate the prognostic factors of PISA, mixed-effect modeling was performed for clinical parameters, tooth-type, and levels of periodontal pathogens as independent variables. One-hundred-twenty-five patients with chronic periodontitis who completed the active periodontal treatment were followed-up for 24 months, with evaluations conducted at 6-month intervals. Five-times repeated measures of mean PISA values were 130+/-173, 161+/-276, 184+/-320, 175+/-417, and 209+/-469 mm2. Changes in clinical parameters and salivary and subgingival periodontal pathogens were analyzed by mixed-effect modeling. Plaque index, clinical attachment level, and salivary levels of Porphyromonas gingivalis were associated with changes in PISA at the patient- and tooth-level. Subgingival levels of P. gingivalis and Prevotella intermedia were associated with changes in PISA at the sample site. For most patients, changes in PISA were within 10% of baseline during the 24-month follow-up. However, an increase in the number of bleeding sites in a tooth with a deep periodontal pocket increased the PISA value exponentially.

Estimation of the Periodontal Inflamed Surface Area by Simple Oral Examination.

The periodontal inflamed surface area (PISA) is a useful index for clinical and epidemiological assessments, since it can represent the inflammation status of patients in one contentious variable. However, calculation of the PISA is difficult, requiring six point probing depth measurements with or without bleeding on probing on 28 teeth, followed by data input in a calculation program. More simple methods are essential for screening periodontal disease or in epidemiological studies. In this study, we tried to establish a convenient partial examination method to estimate PISA. Cross-sectional data of 254 subjects who completed active periodontal therapy were analyzed. Teeth that represent the PISA value were selected by an item response theory approach. The maxillary second molar, first premolar, and lateral incisor and the mandibular second molar and lateral incisor were selected. The sum of the PISAs of these teeth was significantly correlated with the patient's PISA (R2 = 0.938). More simply, the sum of the maximum values of probing pocket depth with bleeding for these teeth were also significantly correlated with the patient's PISA (R2 = 0.6457). The simple model presented in this study may be useful to estimate PISA.

Optimal Examination Sites for Periodontal Disease Evaluation: Applying the Item Response Theory Graded Response Model.

Periodontal examination data have a complex structure. For epidemiological studies, mass screenings, and public health use, a simple index that represents the periodontal condition is necessary. Periodontal indices for partial examination of selected teeth have been developed. However, the selected teeth vary between indices, and a justification for the selection of examination teeth has not been presented. We applied a graded response model based on the item response theory to select optimal examination teeth and sites that represent periodontal conditions. Data were obtained from 254 patients who participated in a multicenter follow-up study. Baseline data were obtained from initial follow-up. Optimal examination sites were selected using item information calculated by graded response modeling. Twelve sites-maxillary 2nd premolar (palatal-medial), 1st premolar (palatal-distal), canine (palatal-medial), lateral incisor (palatal-central), central incisor (palatal-distal) and mandibular 1st premolar (lingual, medial)-were selected. Mean values for clinical attachment level, probing pocket depth, and bleeding on probing by full mouth examinations were used for objective variables. Measuring the clinical parameters of these sites can predict the results of full mouth examination. For calculating the periodontal index by partial oral examination, a justification for the selection of examination sites is essential. This study presents an evidence-based partial examination methodology and its modeling.

Clinical and microbiological effect of frequent subgingival air polishing on periodontal conditions: a split-mouth randomized controlled trial.

The objective of this study was to evaluate the clinical effects of repeated subgingival debridement by air polishing during supportive periodontal therapy. A double-blind, randomized controlled trial of 6 months in duration was conducted on 19 recall patients who were previously treated for chronic periodontitis. Three sites with probing pocket depths (PPD) of 4-9 mm in each of the patients were randomly assigned to the following treatments: Glycine powder/air polishing every 30 days (group 1), glycine powder/air polishing at baseline and on day 90 (group 2), or water irrigation every 30 days (group 3). Clinical parameters were recorded and microbiological sampling was performed at 0, 90, and 180 days post-treatment. Subgingival samples were analyzed using real-time PCR methods for Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola. Between baseline and 90 days, group 1 showed significantly more PPD reduction compared to group 3 and no significant differences with group 2. Between baseline and 180 days, group 1 displayed a significant increase in clinical attachment level compared with group 3. No differences were observed among the groups in numbers of total bacteria or percentage of investigated bacteria at any time point. This study revealed that routine subgingival air polishing at 30-day intervals had significant clinical effects in moderately deep pockets in patients who underwent supportive periodontal therapy.

Current status of periodontal disease in adults in Takahagi, Japan: a cross-sectional study.

BACKGROUND: To date, a few studies have documented the detailed periodontal conditions of a Japanese population. It is important to know if the awareness of Japanese nationals and dentists regarding oral hygiene and prevention of periodontal disease have improved when compared with the past in Japan for the development of future scenarios regarding prevention. The aim of this study was to investigate the severity, prevalence, and extent of periodontal disease in the adult population of the city of Takahagi, Japan. Results were also compared with those of an epidemiological study performed in Japan in the 1980s. METHODS: A total of 582 (aged 20 to 89 years) randomly sampled Takahagi residents answered a comprehensive questionnaire and participated in clinical examinations. RESULTS: The mean percentages of tooth surfaces harboring plaque and exhibiting BOP were 59.5 ± 20.9% and 31.1 ± 21.1%, respectively. The mean PPD and CAL were 2.5 ± 0.5 mm and 2.9 ± 1.0 mm, respectively. Compared with results of the 1980s survey, the mean percentages of plaque and bleeding on probing were lower in the current population. The mean CAL and prevalence of attachment loss of ≥5 mm in some age groups were higher in the present study than in the 1980s study. There were no statistically significant differences with respect to mean probing depth between the 1980s and current age groups. CONCLUSIONS: Periodontal disease was still prevalent in the current Japanese population, even though some improvement occurred. Proper public health programs therefore need to be established.

Site-level progression of periodontal disease during a follow-up period.

Periodontal disease is assessed and its progression is determined via observations on a site-by-site basis. Periodontal data are complex and structured in multiple levels; thus, applying a summary statistical approach (i.e., the mean) for site-level evaluations results in loss of information. Previous studies have shown the availability of mixed effects modeling. However, clinically beneficial information on the progression of periodontal disease during the follow-up period is not available. We conducted a multicenter prospective cohort study. Using mixed effects modeling, we analyzed 18,834 sites distributed on 3,139 teeth in 124 patients, and data were collected 5 times over a 24-month follow-up period. The change in the clinical attachment level (CAL) was used as the outcome variable. The CAL at baseline was an important determinant of the CAL changes, which varied widely according to the tooth surface. The salivary levels of periodontal pathogens, such as Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans, were affected by CAL progression. "Linear"- and "burst"-type patterns of CAL progression occurred simultaneously within the same patient. More than half of the teeth that presented burst-type progression sites also presented linear-type progression sites, and most of the progressions were of the linear type. Maxillary premolars and anterior teeth tended to show burst-type progression. The parameters identified in this study may guide practitioners in determining the type and extent of treatment needed at the site and patient levels. In addition, these results show that prior hypotheses concerning "burst" and "linear" theories are not valid.

Correlation Between Gingival Crevicular Fluid Hemoglobin Content and Periodontal Clinical Parameters.

BACKGROUND: Probing depth (PD) and bleeding on probing (BOP) are essential clinical parameters used for periodontal diagnosis. This study investigated whether detection of hemoglobin (Hb) in gingival crevicular fluid (GCF), along with PD and BOP, would improve diagnostic accuracy. METHODS: After plaque index (PI) was measured, GCF was collected from the gingival sulci of 401 anterior teeth in the maxilla and mandible from 184 patients who had entered periodontal maintenance therapy. Clinical parameters (gingival index [GI], PD, clinical attachment level [CAL], and BOP) were recorded. Hb values in GCF were assessed by immunochromatography. Moreover, cutoff values for PI, GI, and CAL based on the degree of PD and amount of GCF were created and analyzed. RESULTS: Hb was detected in 64.8% of GCF samples in 105 BOP-negative (-) sites in the periodontally stable group out of 107 sites that were less than all cutoff values. There were 71 BOP(-) sites in the periodontal-management-required group out of 122 sites that were more than all cutoff values, although no improvement in periodontal disease was observed. Hb was detected in 88.7% of GCF samples from these 71 BOP(-) sites. CONCLUSIONS: Hb was observed in more than 60% of GCF samples in BOP(-) gingival sulci in both periodontally stable and periodontal-management-required groups. These results suggest inspection of Hb derived from microbleeding in gingival sulci may serve as an index for preclinical diagnosis.

Evaluation of bleeding on probing and gingival crevicular fluid enzyme activity for detection of periodontally active sites during supportive periodontal therapy.

This study aimed to analyze the enzyme activity in gingival crevicular fluid (GCF) and its association with clinical parameters, especially bleeding on probing (BOP), and thus reconsider the significance and accuracy of recording BOP. A total of 184 patients who had entered supportive periodontal therapy were selected and GCF was collected from 401 sites before recording the clinical parameters, probing pocket depth (PPD), BOP, clinical attachment level, gingival index and plaque index. The enzyme activity of neutrophil elastase and aspartate aminotransferase and amount of protein in GCF were also analyzed. In the clinical parameters for biochemical data, amount of GCF showed the most correlation. A cut-off value for BOP and PPD were determined by the ROC curve and Youden index. Analysis was performed with all clinical parameters and biochemical data. Of the 401 sites, 51 were less than the cut-off value and were BOP-negative. On the other hand, 29 sites had values more than the cut-off value, with 14 BOP-negative sites and 15 BOP-positive sites. A conclusion is as follows: twenty-nine sites with values more than the cut-off value were diagnosed as sites requiring periodontal management, however, 14 of these were BOP-negative. These results suggest that combining other biochemical tests with examination of BOP and PPD may improve the validity of periodontal disease diagnosis. In future studies, it will be essential to find a marker that can precisely detect periodontal disease activity, and to develop a diagnostic tool for chair-side use.

Influence of a mandibular fixed orthodontic retainer on periodontal health.

OBJECTIVE: To investigate the impact of bonded mandibular orthodontic retainers on local periodontal health. METHODS: Two groups of subjects were recruited and designated Group F+, individuals who were provided with a fixed wire lingual retainer in the mandibular anterior area following orthodontic treatment and Group F-, individuals with no fixed wire and no clear sign of mandibular anterior malalignment. A clinical examination, a biochemical analysis, and a bacteriological analysis were performed at commencement baseline (BL) and at 1 week (T1), 4 weeks (T2), and at 8 weeks (T3) following retainer placement. The vertical position of the fixed wire relative to the clinical crown height in Group F+ was recorded and the subjects assigned to Subgroups Wi or Wg (the wire nearer or farther from the incisal edge, respectively). RESULTS: Significant increases were found in gingival crevicular fluid (GCF) quantity, elastase activity, and protein content between T1 and T3 for both Group F+ and Group F-. A significant increase in F-Hb concentration was also found in Group F+. A comparison of the two groups identified significant differences for T3-BL in elastase activity and protein content. A Group Wi and Wg comparison showed significant baseline changes only in the F-Hb concentration at T2 and T3. CONCLUSIONS: There was no difference in the status of the periodontal tissue between individuals with and without fixed retainers. In addition, the vertical position of the fixed retainer wire did not appear to influence periodontal health. The result, however, was obtained in subjects who possessed good oral hygiene. Attention should be paid to a patient's oral hygiene when employing the fixed retainer.

Correlations between pentraxin 3 or cytokine levels in gingival crevicular fluid and clinical parameters of chronic periodontitis.

The gingival crevicular fluid (GCF) contains various biomarkers, such as interleukin (IL)-1ß, IL-6, IL-8, tumor necrosis factor-α (TNF-α), and IL-10, among others. These cytokines have been reported to correlate with gingival inflammation and periodontal status. Therefore, the analysis of GCF may be useful for the diagnosis of periodontal status. Pentraxin 3 (PTX3) is the first identified long pentraxin, and is released by several cell types in response to proinflammatory signals. The aim of this study was to determine the levels of IL-1ß, IL-6, IL-8, TNF-α, IL-10 and PTX3 in GCF from diseased and healthy sites in patients with chronic periodontitis. Cross-sectional clinical data were obtained from 50 patients with chronic periodontitis. GCF samples were collected with paper strips from one periodontal diseased site and one periodontally healthy site per subject. The levels of IL-1ß, IL-6, IL-8, IL-10 and TNF-α were determined using a multiplexed bead immunoassay, and the PTX3 level was measured using an enzyme-linked immunosorbent assay. Mean clinical parameters were significantly higher at diseased sites (P < 0.01) as compared to healthy sites, and the mean levels of PTX3, IL-1ß, IL-6, IL-8, IL-10 and TNF-α were higher in diseased sites (P < 0.01) than in healthy sites. There were strong correlations between PTX3 or IL-1ß and periodontal status. These results suggest that GCF PTX3 levels might be useful as a diagnostic marker for periodontal disease.

The effect of a mouth rinse containing phenolic compounds on plaque formation and developing gingivitis.

BACKGROUND: The clinical effect of Listerine, a mouth rinse containing a mixture of phenolic compounds, is ascribed to its bactericidal properties. However, phenolic compounds are also known to interfere with the inflammatory process. OBJECTIVE: The purpose of this clinical trial was to evaluate the effect of regular mouth rinsing with Listerine on plaque and gingivitis during a 2-week period of no mechanical oral hygiene. MATERIAL AND METHODS: Twenty-one subjects were recruited for the study. On Day 0 of each 2-week experimental period, the participants were told to abstain from all mechanical plaque-control measures but to rinse twice a day with 10 ml of the assigned solution (test: Listerine, positive control:0.1% chlorhexidine (CHX), negative control: saline) for 60 s. Each experimental period was preceded by a 2-week period including oral hygiene instruction, scaling and professional mechanical tooth cleaning. Examinations included assessments of plaque and gingivitis (Days 0 and 14), sampling of plaque and collection of gingival crevicular fluid (GCF) (Days 0, 7 and 14). From the supragingival plaque samples, six different morphotypes of bacteria were counted using dark-field microscopy. The GCF collected was analysed with respect to the content of lactoferrin and albumin. RESULTS: During the experimental periods, it was observed that significantly less plaque formed and less gingivitis developed when the participants rinsed with the Listerine mouthwash than with saline solution. However, significantly more plaque formed during the Listerine than during the CHX rinse period, while there was no significant difference in the development of gingival bleeding between the Listerine and the CHX rinse regimens. Significantly smaller proportions of motile rods and fusiforms were found in the List and CHX groups than in the control (Ctrl) group. The increase of the lactoferrin/albumin ratio in the List group was significantly smaller than that in the Ctrl group but significantly larger than in the CHX group. CONCLUSION: It was suggested that the effect of Listerine on gingivitis is more pronounced than on plaque formation. This indicates that the phenolic compound may have anti-inflammatory effects.

The effect of systemic administration of ibuprofen in the experimental gingivitis model.

BACKGROUND: Studies in humans have indicated that systemically administered flurbiprofen and ibuprofen may reduce gingivitis. De novo plaque formation is enhanced at tooth surfaces adjacent to inflamed gingivae. OBJECTIVE: The aim of the present clinical trial was to evaluate the effect of systemic administration of ibuprofen on gingivitis and plaque build-up. MATERIAL AND METHODS: Eleven subjects were recruited for the study and were given oral hygiene instruction, scaling and professional mechanical tooth cleaning (PTC). At the end of a preparatory period (Day 0), the participants were told to abstain from all mechanical plaque control measures during a 2-week experimental period but to rinse with an assigned mouth rinse (positive control: 0.1% chlorhexidine digluconate; negative control: saline) or administer ibuprofen (tablets of 200 mg twice daily). Mouth rinsing was performed twice a day (after breakfast and in the evening), for 60 s with 10 ml. Re-examination was performed after 14 days of experiment. After a 2-week "wash-out" period, the participants received a new PTC and a second 14-day experimental period was initiated. The experimental and "wash-out" periods were repeated until all volunteers had been involved in all three regimens. Dental plaque was scored using the Quigley & Hein Plaque Index system and gingivitis according to the Gingival Index (GI) system. Supragingival plaque was collected and prepared for dark-field microscopy. One hundred bacterial cells were counted and classified into six different groups: coccoid cells, straight rods, filaments, fusiforms, spirochetes and motile rods. Gingival crevicular fluid (GCF) was collected from the same sites that were sampled for plaque. The volume of GCF collected in each strip was measured and analysed regarding content of lactoferrin and albumin. RESULTS: During the period when the panelists rinsed with saline they accumulated large amounts of plaque and developed marked signs of gingivitis. When they rinsed with chlorhexidine digluconate, small amounts of plaque formed and few sites received GI score > or =2. After the 2 weeks of ibuprofen administration, the panelists presented with significantly fewer sites that scored GI > or =2 but had formed similar amounts of plaque as during the negative control period. CONCLUSION: It is suggested that ibuprofen administered via the systemic route has an effect on gingivitis but not on de novo plaque formation.

The effect of a chlorhexidine regimen on de novo plaque formation.

OBJECTIVE: To evaluate the effect of a pretreatment regimen that combined meticulous mechanical tooth cleaning with the daily use of chlorhexidine (rinse, gargle and tongue application) on de novo plaque formation and on the recolonization of various microbiological species in plaque and saliva during a 4-day period of no oral hygiene. MATERIAL AND METHODS: Ten subjects aged 24-36 years with gingivitis were recruited. The study was designed as a double blind cross-over clinical trial including two phases. Each experimental phase comprised one preparatory period of 7 days and one plaque accumulation period of 4 days. During the preparatory period, the volunteers (i) performed meticulous mechanical tooth cleaning using toothbrush and dentifrice and (ii) were, in addition, given two sessions of professional tooth cleaning (PTC) The final PTC was delivered after bacterial sampling had been made on Day 0. In the Control group, no additional plaque control measures were included. In the Test group, the participants in addition to the mechanical measures (i) rinsed twice daily, for 60 s each time with a 0.2% chlorhexidine solution, (ii) gargled twice daily for 10 s with the chlorhexidine preparation, and finally (iii) brushed the dorsum of the tongue for 60 s, twice daily, with a 1.0% chlorhexidine gel. During the 4-day plaque accumulation period, the participants abstained from all mechanical and chemical plaque control measures. On Days 0, 1, 2 and 4 the quantity and quality of plaque formed was assessed by clinical means and by DNA probe techniques. The microbiota of the saliva was studied in samples obtained on Days 0 and 4. RESULTS: It was demonstrated that chlorhexidine used as a mouthrinse combined with gargling and tongue application during the preparatory period significantly retarded the amount of plaque that formed on tooth surfaces during the following 4 days of no oral hygiene. Further, the number of microorganisms present in the biofilm representing Days 0, 1 and 2 of the "plaque accumulation period" was apparently affected by the use of the antiseptic. Among the microorganisms influenced by the chlorhexidine regimen, a substantial number belonged to the genus Actinomyces. It was also observed that the adjunctive use of chlorhexidine reduced the number of bacteria present in saliva at the end of the preparatory period (i.e. on Day 0). After 4 days of no oral hygiene, the microbiota of the newly formed plaque in the Test and Control groups had many features in common. CONCLUSION: Habitat is critical in controlling the bacterial composition of the dental biofilm. The microbiota will tend to go back to the one that is characteristic of a given subject, once chemical antimicrobial means are withdrawn.

Tissue reactions to abutment shift: an experimental study in dogs.

BACKGROUND: Standard protocols for the clinical use of dental implants often include the placement of healing abutments prior to standard or custom-made abutments. The tissue response to a single shift from a healing abutment to a permanent abutment has not been studied. PURPOSE: The aim of the present experiment was to study tissue reactions that may occur following the removal of a healing abutment and the placement of a permanent abutment. MATERIALS AND METHODS: In six beagle dogs, all mandibular premolars were extracted. Three months later three fixtures of the Astra Tech Implants Dental System (Astra Tech AB, Mölndal, Sweden) were installed in each edentulous premolar region. An additional 3 months later, the first abutment connection was performed. In two sites on each side of the mandible, healing abutments were placed; in the remaining site, a Uni-abutment (Astra Tech AB) was used. The two healing abutments were removed 2 weeks later, and one Uni-abutment and one prepable abutment were placed. A plaque-control period was initiated, and 6 months later block biopsies were obtained. The biopsies were prepared for histometric and morphometric examination. Radiographs were obtained at fixture placement, 2 weeks after the first abutment connection, and 6 months later. RESULTS: The length of the barrier epithelium, the height of the connective tissue attachment, and the level of the marginal bone did not differ between the three abutment groups. The major part of the radiographic bone loss during the experiment took place prior to or immediately after abutment connection; only small bone level alterations occurred during the subsequent 6-month period. CONCLUSIONS: The shift from a healing abutment to a permanent abutment resulted in the establishment of a transmucosal attachment, the dimension and quality of which did not differ from those of the mucosal barrier formed to a permanent abutment placed during a second-stage surgery.

Effect of various chlorhexidine regimens on salivary bacteria and de novo plaque formation.

AIM: The aim of the present experiment was to study the effect of different chlorhexidine regimens on the number of bacteria in saliva, and on de novo plaque formation. MATERIAL AND METHODS: Ten subjects with gingivitis, but no signs of destructive periodontitis, were recruited. Following a screening examination, the volunteers were given oral hygiene instruction, meticulous scaling and professional mechanical tooth cleaning (PTC). The PTC was repeated once every 3 days during a 2-week period to establish healthy gingival conditions. The study was designed as a double-blind cross-over clinical trial including three phases. Each experimental phase comprised one preparatory period of 7 days and one plaque accumulation period (no oral hygiene measures) of 4 days. During all preparatory periods, the volunteers (i) performed mechanical tooth cleaning using a toothbrush and dentifrice and (ii) were, in addition, given two sessions of PTC. The final PTC was delivered after bacterial sampling had been made on Day 0. Preparatory period A: the participants continued the self-performed plaque control regimen that employed only mechanical means. Preparatory period B: the participants were in addition instructed to rinse and gargle, twice daily, with a 0.2% chlorhexidine mouthrinse. Preparatory period C: in addition to the above, the participants were instructed to brush the dorsum of the tongue for 60 s, twice daily, with a 1.0% chlorhexidine gel. Following each plaque accumulation period, there was a 10-day washout interval. The presence and amount of dental plaque (QHI) was scored after 1, 2 and 4 days of no oral hygiene. Samples of saliva were obtained on Day 0 and after 1 and 2 days. The samples were placed on Brucella agar plates and incubated (anaerobically) for 5 days. The total number of colony-forming units was determined and used to estimate the density of bacteria in saliva. RESULTS: In period A, the mean QHI increased from 1.0 (Day 1) to 1.4 (Day 2) and 2.1 (Day 4). The corresponding scores for periods B and C were 0.5, 0.8, 1.6 and 0.3, 0.8, 1.2, respectively. At all re-examination intervals more plaque formed during period A than during periods B and C. Further, during period C, less plaque formed than that during period B. Saliva samples from Day 0 in period A contained a larger number of TVC than the baseline samples in periods B and C. There was no significant difference in TVC among the groups on Day 2. CONCLUSION: The daily use of chlorhexidine as an adjunct to mechanical tooth cleaning markedly reduced the number of microorganisms that could be detected in saliva. The number of salivary bacteria may have influenced the amount of plaque that formed during an early phase of no oral hygiene.

Bacterial colonization during de novo plaque formation.

OBJECTIVE: To determine microbial changes that occur during plaque formation in a dentition free of gingival inflammation. MATERIAL AND METHODS: Ten subjects were recruited. The study included one preparatory period (2 weeks) and a plaque accumulation period (4 days). The volunteers exercised proper tooth cleaning methods, were scaled and received repeated professional mechanical tooth cleaning during the preparatory period. During the plaque accumulation period, the participants abstained from plaque control measures. Plaque was scored on the approximal surfaces of maxillary and mandibular premolars on Days 0, 1, 2 and 4 using a scale from 0 to 5 and according to the criteria of the Quigley and Hein Plaque Index (QHI). Supragingival plaque samples were obtained from the same intervals and surfaces and evaluated using a checkerboard DNA-DNA hybridization technique. RESULTS: The mean QHI increased from 0 to 1.6 (Day 4). The total number of organisms on Day 0 averaged 140 x 10(5) and increased to about 210 x 10(5) after 4 days without oral hygiene. The most dominant species on Day 0 were members of the genus Actinomyces. These organisms comprised almost 50% of the microbiota evaluated. None of the Actinomyces species increased significantly during the 4 days. Some Streptococcus species increased significantly over time as well as species of the genera Capnocytophaga, Campylobacter, Fusobacteria and Actinomyces actinomycetemcomitans. CONCLUSION: In the present investigation, the preparatory phase established a situation with minimal gingival inflammation and close to zero amounts of dental plaque. The Day 0 plaque samples exhibited high proportions of Actinomyces species. During the 4 days of no oral hygiene, there was a small increase in total numbers of organisms as well as a modest increase in the proportion of "disease-associated" taxa such as species of the "orange complex" species.