The influence of gingival inflammation on de novo plaque formation

Abstract The aim of the present clinical trial was to examine the influence of gingival inflammation on de novo plaque formation. In addition, the effect of a varying number of salivary bacteria on early plaque formation was evaluated. 10 subjects were recruited for the trial which was designed to establish 2 different starting points for de novo plaque formation. 1 in a healthy dentition and 1 in a gingivitis dentition. On Day 0 and at regular intervals during a 5-week period, the panelists were examined with respect to gingivitis, plaque and number of salivary bacteria. The findings from the study demonstrated that the condition of the marginal gingiva plays an important role in the early stages of plaque formation. Thus, in both phases of the study, it was observed that at sites with initially healthy gingival units, less plaque formed (PII=0.93 and 0.82) than at sites with G1 > 0 (PII= 1.24 and 1.28) at the 2 different starting points. The number of salivary bacteria seemed to be less important than the state of the gingiva for the amount of plaque that formed during a 4-day period of no active mechanical tooth cleaning.     

Patterns of de novo plaque formation in the human dentition

The objective of the present clinical trial was to carefully assess the pattern of de novo plaque formation in the human dentition. 10 subjects aged 24-29 years were recruited for the study. None of the participants showed signs of destructive periodontitis. At the start of the preparatory period, they were given a thorough dental prophylaxis and oral hygiene instruction. For the next 2 weeks, the participants were carefully monitored and 1 x every 2 days examined with respect to plaque and gingivitis. At the re-examinations, they were also given professional tooth cleaning and instruction in proper plaque control measures. Towards the end of this 2-week period, the Day 0 examination was performed which revealed that the gingival tissues of all participants were in excellent clinical health. Following the Day 0 examination, all 10 subjects were exposed to professional tooth cleaning. During the next 14 days, they abolished all mechanical tooth cleaning efforts but were examined with respect to plaque on Days 1, 4, 7 and 14. The amount of plaque formed was examined using the criteria of the Plaque Index system (PlI). Each of 6 surfaces of each tooth in the dentition was given a score from 0 to 3. The results from the re-examinations demonstrated that in humans with clean teeth and normal gingiva, the abolishment of mechanical tooth cleaning rapidly resulted in de novo plaque formation. Most plaque, as assessed by the plaque index system, formed during the first 4 days of no tooth cleaning after which moderate additional amounts of plaque formed. It was observed that the mean PlI values for individuals, for groups of teeth and tooth surfaces, provide a proper overall estimation of plaque build up. The dynamics of plaque formation between examinations and in different parts of the dentition were more easily disclosed by the data describing % distributions of different score categories and the transition between scores from one examination to the next. The total amount of plaque formed on various tooth surfaces was best presented by so called "plaque pattern displays". The results also revealed that (i) the mandibular dentition harbored more plaque than the maxillary dentition, (ii) there was a difference in the mean PlI scores between the molar and the anterior tooth regions in the maxilla, but in the mandible such a difference could not be observed (except on Day 1), (iii) plaque accumulated most at the approximal surfaces and least at the palatal surfaces, and that (iv) differences in PlI scores between groups of teeth and tooth surfaces observed on Day 4 persisted through the Day 14 examination.     

The effect of age on the development of gingivitis

Abstract In the present “experimental gingivitis” study, the response of the marginal gingiva to plaque formation was studied in one group of young subjects, 20-25 years of age, and in one group of older subjects, aged 65-80 years. During a 4-week period, all subjects received a series of professional tooth cleaning to establish healthy gingival conditions. A baseline examination (Day 0) included assessments of plaque and gingivitis. Sites that were examined (the experimental sites) included the mesiopalatal, palatal, and dislopalatal surfaces of all teeth present in the 15. 25 tooth region. Among the experimental sites, microbial sampling and gingival fluid assessment were performed and one gingival biopsy harvested from each subject. Following the baseline examination, the participants abolished mechanical tooth cleaning measures in the palatal and approximal surfaces of 15, 25. The clinical examination and the gingival fluid measurement were repeated on days 7, 14 and 21 of no oral hygiene. The microbiological sampling and the biopsy procedure were repeated on days 7 and 21. The data collected demonstrated that old subjects, during a 3-week period of oral hygiene abstention, formed similar amounts of plaque as the young subjects, but developed more gingivitis than young subjects. Thus, the clinical gingivitis assessments, the gingival fluid measurements and morphometric determinations made in the biopsy samples documented that the gingival lesion which formed in the old individuals was more pronounced and contained more inflammatory cells than the corresponding lesion in the young subject sample.     

The effects of antimicrobial mouthrinses on de novo plaque formation at sites with healthy and inflamed gingivae

Abstract The objective of the present investigation was to evaluate to what extent mouthrinses containing triclosan and chlorhexidine may modify the amount of de novo plaque that forms on tooth surfaces adjacent to healthy and inflamed gingival units. 10 volunteers were recruited. On day 0, gingival crevicular fluid (GCF) was obtained at predetermined sites and gingivitis (GI) was assessed. A careful oral profylaxis was given to each of the volunteers who subsequently abstained from all mechanical plaque control measures for the following 18 days. During the first 4 days (rinse phase I), they rinsed with either 0.12% chlorhexidine. 0.06% triclosan or placebo solution. Clinical examinations (GCF, GI) were repeated and the amount of plaque formed determined on days 4, 7 and 14. On day 14, the participants received a new professional tooth cleaning after which rinse phase II was initiated. During this 2nd phase, the participants rinsed for 4 days with the same mouthwash preparation and in the same manner as during rinse phase I. The examinations were repeated on day 18. Each participant received a comprehensive oral prophylaxisis and was instructed to perform meticulous mechanical plaque control during the following 4 weeks. A 2nd experimental period was then initiated. A total of 3 experimental periods were repeated until all subjects had rinsed with the 3 different mouthwash preparations. The results demonstrated (i) that significantly more plaque formed at sites with gingivitis than at surfaces adjacent to healthy gingival units and (ii) pre-existing gingivitis significantly increased the amount of de novo plaque that formed in subjects who rinsed with mouthwash preparations containing chlorhexidine and triclosan.     

Plaque and gingivitis in the deciduous and permanent dentition

Abstract The aim of the present investigation was to monitor de novo plaque formation and associated alterations of the gingival conditions in the deciduous, mixed and permanent dentition in man. 31 volunteers, divided into 3 study groups participated in the trial. Group 1 was made up of 11 subjects, 4–6 years of age (deciduous dentition), group 2 comprised of 10 subjects, 8–9 years of age (mixed dentition) and group 3 included 10 subjects, 14–16 years of age (permanent dentition). After a screening examination, each participant received detailed instruction in a proper oral hygiene technique and was subjected to professional tooth cleaning. The professional debridement and the oral hygiene instruction were repeated after 1 week. After another week, a given day was termed Day 0 and a baseline examination was performed. This examination included assessments of plaque and gingivitis. Each subject received an additional, comprehensive professional tooth cleaning and was asked to abstain from all mechanical oral hygiene measures. Re-examinations were performed after 3 and 7 days. The findings demonstrated that: (i) during a 7-day period of no active oral hygiene, subjects with a mixed or a permanent dentition formed visible amounts of plaque and developed modest signs of gingivitis; (ii) during the 7 days of the trial, young subjects with a fully erupted deciduous dentition formed less plaque than the older subjects, and failed to respond to de novo plaque formation with enhanced signs of gingivitis; (iii) in subjects with a mixed dentition, the amount of plaque formed during the 7 days of experiment and the matching gingivitis development were similar in the deciduous and permanent tooth segments of the dentition.     

Differences in the inflammatory response in young and old human subjects during the course of experimental gingivitis

The aim of the present experiment was to study changes in (i) the composition of the inflammatory cell infiltrates and (ii) levels of alpha 2-macroglobulin, lactoferrin and IgG subclasses in gingival crevicular fluid in young and old individuals during 3 weeks of plaque formation. To establish healthy gingival conditions, all subjects received professional tooth cleaning during a 4 week pre-experimental period. The experimental sites included the mesio-palatal, palatal, and disto-palatal surfaces of all teeth present in the 15...25 tooth region. At baseline (day 0) assessments of plaque and gingivitis, microbial sampling and gingival fluid assessment were performed and one gingival biopsy harvested from each subject. Following the baseline examination, the participants abolished mechanical tooth cleaning measures in the palatal and approximal surfaces of 15...25. The clinical examination and the gingival fluid measurement were repeated on days 7, 14 and 21 of no oral hygiene. The microbiological sampling and the biopsy procedure were repeated on days 7 and 21. The gingival crevicular fluid samples harvested from the old individuals had higher levels of alpha 2-macroglobulin and IgG3 compared to young subjects. The immunohistochemical analyses of the biopsies demonstrated that the gingival lesion representing the old individuals harbored a higher proportion of B-cells and a lower density of PMN cells compared to the infiltrate in the young group of subjects. It is suggested that differences exist in the inflammatory response to de novo plaque formation in young and old individuals.     

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 metronidazole on the development of plaque and gingivitis in the beagle dog

The present investigation was performed in order to assess if the administration of metronidazole changed the composition of developing plaque in dogs, which at the start of the study were free from signs of gingivitis. Five beagle dogs were used. Throughout the observation period the animals were fed a diet which favored plaque accumulation. A baseline examination involved assessments of plaque, gingivitis and gingival exudate. Gingival biopsies were sampled and the tissue examined by a point counting procedure. The composition of the subgingival bacterial flora was assessed by dark-field microscopy. The bacteria were characterized into the following types: coccoid cells, straight rods, filaments, fusiforms, motile and curved rods and spirochetes. Following the baseline examination the teeth of the right jaws were allowed to accumulate plaque. A careful tooth cleaning program was maintained in the left jaw quadrants. Plaque and gingivitis assessments were repeated and biopsies sampled in the right jaws after 7, 14 and 28 days of no tooth cleaning. On experimental day 28 the second part of the study was initiated. A baseline examination was performed in the left jaws, after which the tooth cleaning program also in this part of the dentition was terminated. During the subsequent 28-day period each animal was given a dosage of 20 mg metronidazole/kilogram bodyweight/day. Clinical examinations and biopsies were repeated after 7, 14 and 28 days. The results demonstrated that metronidazole administered via the systemic route during a 28-day period can effectively decrease plaque and gingivitis development in dogs. The bacterial flora from subgingival sites of healthy gingiva was dominated by coccoid cells and straight rods. During the phase of developing gingivitis the percentage of coccoid cells and rods tended to decrease, while motile rods and spirochetes increased. During the 28 days of metronidazole treatment the subgingival plaque flora maintained its "healthy" composition, i.e. a gradual influx of motile rods and spirochetes was prevented.     

The effect of periodontal treatment on the salivary bacterial load and early plaque formation

AIM: The purpose of the present study was to investigate in periodontitis patients the relationship between the number of bacteria in the saliva and the amount of de novo plaque formation before and after treatment. METHODS: At baseline, before any treatment was provided, patients rinsed with 10 ml sterile saline. After professional tooth cleaning the patients were instructed to abolish all tooth cleaning procedures for the subsequent 24 h. After this period, the rinsing procedure was repeated and the amount of de novo plaque was assessed. Three months after the initial periodontal therapy was completed the experiment was repeated. The microbiological evaluation of the rinsing samples was carried out by means of phase contrast microscopy and anaerobic culturing. RESULTS: After treatment the amount of de novo plaque was less compared to before treatment, 0.40 and 0.65 respectively. Both before and after treatment more de novo plaque was present at sites with inflammation than at healthy sites. In order to evaluate the contribution of the numbers of salivary bacteria to the amount of de novo plaque formation an analysis was carried out for healthy sites. This analysis included only healthy sites as determined before treatment and the same sites after treatment. The results showed a significant reduction in the de novo plaque formation after treatment (0.49 before and 0.22 after treatment). Phase contrast microscopic evaluation showed that the number of bacteria in the rinsing samples after treatment was less than before treatment. After treatment also a reduction was found in the prevalence of Prevotella intermedia, Tannerella forsythensis and Peptostreptococcus micros in the rinsing samples. CONCLUSION: The present study confirms the observation in the literature that the periodontal condition is of major importance in the rate of de novo plaque formation. In addition, the results suggest that the number of bacteria in the saliva may play a role.     

Soft tissue reaction to de novo plaque formation on implants and teeth. An experimental study in the dog

The aim of the present investigation was to assess the effect of de novo plaque formation on the gingiva and masticatory mucosa around teeth and implants. The study was performed in 5 beagle dogs which at the initiation of the experiment were 15 months old. During a preparatory period, the mandibular right premolars were extracted, 3 fixtures installed, abutment connection performed and a 4-month period of plaque control completed. A clinical examination was performed and biopsies of the second mandibular premolar (P2) and the contralateral implant site (2P) were sampled. The dogs were allowed to form plaque during a period of 3 weeks. The clinical examination was repeated and biopsies harvested from the 2 remaining implants and the contralateral tooth sites. The tissue samples were prepared for histometric and morphometric analysis. Both the masticatory mucosa at implants and the gingiva responded to de novo plaque formation with the development of an inflammatory lesion. The size as well as the composition of the lesions in the 2 tissues had many features in common. It was concluded that the mucosa around implants and the gingiva around teeth had a similar potential to respond to early plaque formation.     

Dental biofilms at healthy and inflamed gingival margins

Objectives: The increased plaque formation observed in gingival inflammation is not fully understood. Receptor proteins in the dental pellicle might influence bacterial adhesion and subsequent plaque formation. The purpose of the present study was to examine proteins and microorganisms in dental biofilms, at healthy and inflamed gingival margins. Material and methods: To see whether marginal inflammation affects the composition of the pellicle and the early dental plaque, samples were taken from the gingival and incisal parts of teeth in periodontally healthy subjects, both in gingival health and during experimental gingivitis. Pellicle proteins were analysed using gel-electrophoresis, immunoblotting and image analysis. Bacteria were analysed by culturing and the PCR technique. Results: During gingivitis, the rate of plaque formation increased significantly. The semiquantitative amounts of proteins and the numbers of bacteria varied considerably between individuals and surfaces. The amount of total and individual pellicle proteins and the total numbers of bacteria were, however, increased during gingivitis and the increase in proteins was statistically significant on the incisal parts of tooth surfaces. Compared to a healthy gingiva, reduced numbers for Actinomyces spp. (incisal parts only) and streptococci and increased numbers of periodontopathogens in the 4 h dental biofilms were seen at the inflamed gingiva. Conclusion: Increased gingival crevicular fluid flow during gingivitis affects pellicle formation and increased plasma proteins in the pellicle may modify bacterial attachment and early dental plaque composition.     

Some effects of mouthrinses containing salifluor on de novo plaque formation and developing gingivitis

Abstract Three clinical trials were carried out to evaluate the effects of mouth-rinses containing 5n-oetanoyl-3’trifluormethylsalieylanilide (salifluor) on plaque and gingivitis. Each trial was performed as a double-blind, randomised and cross-over designed study (studies 1. 2 and 3). In each study, 10 young individuals with healthy gingiva abolished all means of mechanical plaque control during the course of the experimental period including 6 × 4 days (study 1), 3 × 18 days (study1) and 3 × 14 days (study 2). They rinsed, 2 × daily, with various mouthwash preparations for 4 days (study 1), for the last 4 days of a 18 day period (study 2) or for 14 days (study 3), 6 (control, vehicle control, 0.08%. 0.12% and 0.2% salifluor and 0.12% chlorhexidine), 3 (control, 0.12% salifluor and 0.12% chlorhexidine) and 3 (control, 0.12% salifluor and 0.12% chlorhexidine) mouthwash preparations were tested in studies 1, 2 and 3 respectively. The findings of study 1 indicated that (i) mouthrinses containing salifluor were significantly more effective than control rinses and that (ii) the salifluor mouthrinses were equally effective as the 0.12% chlorhexidine mouthrinse, in retarding 4-day de novo plaque formation. The findings of study 2 indicated that (i) the mouthrinse containing 0.12% salifluor retarded de novo plaque formation to the same extent as the 0.12% chlorhexidine mouthrinse at healthy as well as at inflamed sites but that (ii) the anti-plaque effects of the salifluor and chlorhexidine mouthrinses were significantly smaller at sites with inflamed than with healthy gingiva. In study 3, it was observed that there was no significant difference between the 0.12% salifiuor and 0.12% chlorhexidine mouthrinses in retarding de novo plaque formation and the development of gingivitis during a 14-day period of no mechanical plaque control. Thus, the results of the 3 clinical trials demonstrated the potential of salifluor as an effective anti-plaque and anti-inflammatory agent.     

Effects of cyclosporine A on plasma cells in experimental gingivitis in dogs

Abstract The aim of the present investigation was to evaluate the effect of Cyclosporine A (CsA) on the inflammatory lesion formed in the gingival tissues during de novo plaque formation. 5 beagle dogs were used. On day 0, all teeth of the 5 dogs were scaled and polished. A 6-week period of plaque control including daily tooth cleaning with toothbrush and dentifrice was initiated. A clinical examination regarding plaque and gingivitis was performed, and the plaque control measures were abandoned on the right side of mandible. 3 weeks later, the clinical examination was repeated, samples of subgingival plaque harvested and biopsies obtained from the 3rd and 4th right mandibular premolar regions. The tooth cleaning measures on the left side of the mandible were terminated at this interval. During the following 3 weeks, the animals formed plaque in the lower left premolar regions, and received, 1 × daily, a subcutaneous injection of CsA. At the end of this 2nd plaque formation period (test), the clinical examination was repeated, subgingival plaque was sampled and biopsies from the 3rd and 4th left mandibular premolar regions harvested. The biopsies were prepared for histometric and morphometric analyses. The clinical and histological examinations demonstrated that plaque formation resulted in a gingival lesion (ICT) which, in the 2 periods, had similar size and apical extension. The ICT formed during the CsA administration period, however, harbored an increased number of plasma cells and a reduced macrophage density than the control lesion. It is suggested that CsA administration may result in a Th-2 (T-helper 2-cell) dependent activation of B-lymphocytes.     

Histologic characteristics of experimental gingivitis in the juvenile and adult beagle dog

Abstract An earlier study (Matsson & Attström 1979) revealed an unexplained difference between juvenile and adult dogs in the propensity to develop clinical signs of gingivitis. The aims of the present investigation were to depict the structural composition of clinically normal gingiva and to analyze the histologic changes in the gingiva during plaque development in juvenile and adult dogs. Six beagle dogs were used. Two periods of discontinued oral hygiene were studied, the first at 3 and the second at 12 months of age. Biopsies were sampled on days 0, 4, 7, 14, 21 and 28 of each period. Sections from the biopsies were analyzed at two levels of magnification. Compared to adult dog gingiva, juvenile gingiva seemed to display: 1) a thicker keratinized layer of the oral epithelium, 2) a junctional epithelium that structurally resembles the oral epithelium, 3) a cuticular structure at the surface of the junctional epithelium, 4) a limited mononuclear inflammatory cell response during experimental gingivitis, and 5) a delayed establishment of an infiltrated connective tissue portion during experimental gingivitis. In addition, during experimental gingivitis, subgingival plaque formed along the tooth surfaces to a lesser extent in the juvenile stage compared to adult dogs.     

A model for studying the effects of mouthrinses on de novo plaque formation.

The aim of the present study was to describe a 4-day no oral hygiene model to assess the pattern of de novo plaque formation and to use this model to appraise the potential of some mouthwash preparations to retard or inhibit plaque formation in the human dentition. 10 subjects were recruited for the trial. During a preparatory period, the participants were exposed to repeated professional plaque control and given oral hygiene instruction to eliminate signs of gingivitis. At the end of the preparatory period, each participant received a final professional tooth cleaning and was subsequently told to abstain from mechanical plaque control efforts for the next 4 days. They were asked to rinse twice daily for 60 s with 10 ml varying test solutions. On Day 4, the volunteers were exposed to a new clinical examination and the presence and amount of plaque were examined by the use of the plaque index system (P1I). The participants were subsequently given a professional tooth cleaning and asked to exercise proper self performed plaque control during the next 10 days. A new test period was then initiated. 6 different mouthwash preparations were tested in each subject namely, (1) placebo (a negative control rinse), (2) Veadent mouthrinse, (3) Listerine mouthrinse, (4) 0.06% triclosan + polyvinyl phosphonic acid (PVPA), (5) 0.06% triclosan + phenolic flavor and (6) 0.12% chlorhexidine digluconate (a positive control rinse). The results from the study revealed that the mean P1I values for individuals, groups of teeth and tooth surfaces provide an adequate but gross overall estimation of the potential of a given mouthrinse to retard/inhibit plaque build up. More detailed information on the effects of the test rinses could be obtained by data describing the % distribution of different P1I score categories; a high frequency of score 0 describes the potential of a mouthrinse to maintain tooth surfaces free from plaque while a low frequency of score 2/3 describes the ability of a treatment to retard/prevent gross plaque formation. The plaque pattern displays finally allowed assessment of the magnitude of plaque prevention, in comparison to the positive and negative controls, that could be achieved by a given compound in various parts and surfaces of the dentition. In this model, all test rinses (i) were significantly more effective than the placebo rinse in retarding de novo plaque build up and (ii) had a minor effects on plaque build up in the maxillary molars and at the approximal surfaces.(ABSTRACT TRUNCATED AT 400 WORDS)     

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.     

Experimental gingivitis in immunized dogs

The present experiment was performed to study the clinical and histopathological features of developing gingivitis in eight dogs, of which four were repeatedly immunized with plaque antigens prior to the start of a defined plaque accumulating period. The dogs were, after weaning, fed a soft diet but also twice daily subjected to meticulous tooth cleaning. When they were 10 months old and their gingiva were in excellent health, all tooth cleaning procedures were terminated and dental plaque was allowed to accumulate for 4 weeks. Clinical examinations and gingival biopsy sampling were performed during this period. The biopsies were analyzed morphometrically.
In the injected dogs the levels of specific serum antibodies, as determined by an immunoradiometric assay (IRMA), were raised 3–4 fold. No antibody increase was observed in the controls. After the termination of the tooth-cleaning period, the immunized dogs seemed to accumulate dental plaque at the same rate as non-immunized controls. The gingiva of the immunized animals reacted to initial plaque formation with symptoms such as redness, swelling and bleeding in a manner very similar to the controls. The degree of gingival exudation and the size of the gingival connective tissue lesion was, however, less pronounced in the immunized dogs compared to the non-immunized controls.
The results indicate that raised immunity to plaque antigens may have a protective function in the dento-gingival tissues during the development of plaque induced gingivitis.     

Measuring plaque in clinical trials: index or weight?

AIM: To explore the possibility of using plaque weight rather than plaque index as a more objective, clinical outcome measure in periodontal clinical trials. MATERIALS AND METHODS: The study initially recruited 12 healthy volunteers who abstained from tooth cleaning for 24 h on each of the three occasions and then for 48 h on each of a further three occasions to accumulate plaque. On a further three visits, the subjects abstained from tooth cleaning for 24 h and then brushed with a powered toothbrush for 2 min. A split-mouth design with target teeth was adopted and plaque was first scored separately on each side of the mouth using the Turesky modification of the Quigley and Hein plaque index. Post-brushing residual plaque was also scored after tooth cleaning. Inter-proximal plaque was dried, removed, pooled and weighed: on one side of the mouth from the entire inter-proximal surfaces; and from beneath the contact points on the contra-lateral side. RESULTS: Discriminant validity showed the index to have an advantage over weight in discerning between 24- and 48-h plaque deposits, and between 24-h plaque and post-brushing plaque. Test-retest validity confirmed that for repeated plaque growth, variability within subjects was greater than the variability between subjects. There was an association between plaque weight and plaque index although the regression lines were non-linear. CONCLUSION: There appears to be no significant advantage in using plaque weight in periodontal clinical trials.     

Pellicle and early dental plaque in periodontitis patients before and after surgical pocket elimination

Abstract Objective. Gingival inflammation may affect the composition of the dental pellicle and initial acquisition of bacteria, which in turn could affect the healing of the periodontal pocket. The aim of this study was to examine the dental pellicle and early supragingival biofilms in periodontitis patients with an established subgingival infiltrate before and after surgical pocket elimination. Materials and methods. Eleven patients with remaining pockets were selected. Samples were taken before and after surgical pocket elimination and after subsequent experimental gingivitis. Pellicle proteins were analyzed by SDS-PAGE, immunoblotting and image analysis and 4-h supragingival plaque by culturing. Results. The inflammatory status affected to a greater extent the concentration of plasma proteins than salivary proteins in the dental pellicle. The highest plasma protein concentrations were observed at remaining periodontal pockets where also the highest bacterial counts were found. The TVC was reduced on the gingival tooth surfaces (p < 0.05) after pocket elimination and increased slightly during experimental gingivitis. The finding of streptococci was highest on the incisal tooth surfaces and increased after surgery. Gram-negative anaerobes were sparse but seen more often before than after pocket elimination and on gingival than on incisal surfaces. Conclusions. This study suggests that increased amounts of plasma proteins in the pellicle formed in the presence of remaining periodontal pockets may foster the acquisition of bacteria, including proteolytic Gram-negative species. This, in turn, results in an increased de novo plaque formation rate.     

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.