Scanning electron microscope study of the formation of dental plaque

Biocompatibility and Antimicrobial Activity of Reynoutria elliptica Extract for Dental Application

This study was conducted to determine whether nature-derived Reynoutria elliptica extracts exhibit biocompatibility and antimicrobial effects against oral pathogens such as Streptococcus mutans and Candida albicans. Fine particles of Reynoutria elliptica extract were used to probe for biocompatibility and antimicrobial activity toward these pathogens, and results were evaluated with an MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay, spectrophotometric growth inhibitory assay, the total number of colony-forming units (CFU), an agar disk diffusion test, and scanning electron microscopy (SEM). In addition, UV/VIS spectroscopy was used to determine the levels of flavonoid and polyphenol in experimental solutions. Several experimental groups showed cell viability higher than 70%, and the antimicrobial activity toward both S. mutans and C. albicans was significantly higher than was that seen for the control group. In CFU and agar disk diffusion tests with C. albicans, increases in the concentration of Reynoutria elliptica extract led to significantly increased antimicrobial effects. Additionally, SEM results showed that Reynoutria elliptica extract changed the morphology and density of S. mutans and C. albicans. The results of this research can be applied to the use of Reynoutria elliptica extracts for the development of oral products that are biologically friendly and can control oral diseases such as dental caries and candida-associated denture stomatitis.

Microbiome of dental implants and its clinical aspect

Although dental implants are most common prosthetic treatment used to replace missing tooth, it gained considerable importance over a decade owing to the availability of advanced imagery techniques that can help in achieving a greater success rate and much better osseointegration. However, the chances that the implanted tooth can be rejected due to inflammation caused by oral microflora still persist. This review gives the viewers an overall idea of the dental implants, role of advanced imaging in implantation and instances of peri-implantitis that occur after implantation process. This review also entails the latest research on the different treatment modalities against peri-implantitis documented in peer-review journals.

The Oral Microbiota

The oral microbiota represents an important part of the human microbiota, and includes several hundred to several thousand diverse species. It is a normal part of the oral cavity and has an important function to protect against colonization of extrinsic bacteria which could affect systemic health. On the other hand, the most common oral diseases caries, gingivitis and periodontitis are based on microorganisms. While (medical) research focused on the planktonic phase of bacteria over the last 100 years, it is nowadays generally known, that oral microorganisms are organised as biofilms. On any non-shedding surfaces of the oral cavity dental plaque starts to form, which meets all criteria for a microbial biofilm and is subject to the so-called succession. When the sensitive ecosystem turns out of balance - either by overload or weak immune system - it becomes a challenge for local or systemic health. Therefore, the most common strategy and the golden standard for the prevention of caries, gingivitis and periodontitis is the mechanical removal of this biofilms from teeth, restorations or dental prosthesis by regular toothbrushing.

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

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.

In vitro inhibition of oral streptococci binding to the acquired pellicle by algal lectins

AIMS

The initial colonization of the tooth by streptococci involves their attachment to adsorbed components of the acquired pellicle. Avoiding this adhesion may be successful in preventing caries at early stages. Salivary mucins are glycoproteins that when absorbed onto hydroxyapatite may provide binding sites for certain bacteria. Algal lectins may be especially interesting for oral antiadhesion trials because of their great stability and high specificity for mucins. This work aimed to evaluate the potential of two algal lectins to inhibit the adherence of five streptococci species to the acquired pellicle in vitro.

METHODS AND RESULTS

The lectins used were extracted from Bryothamnion triquetrum (BTL) and Bryothamnion seaforthii (BSL). Fluorescence microscopy was applied to visualize the ability of fluorescein isothiocyanate-labelled lectins to attach to the pellicle and revealed a similar capability for both lectins. Streptococcal adherence assays were performed using saliva-coated microtitre plates. BSL inhibited more than 75% of Streptococcus sanguis, Streptococcus mitis, Streptococcus sobrinus and Streptococcus mutans adherence, achieving 92% to the latter. BTL only obtained statistically significant results on S. mitis and S. sobrinus, whose adherence was decreased by 32.5% and 54.4%, respectively.

CONCLUSION

Algal lectins are able to inhibit streptococcal adherence.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results support the proposed application of lectins in antiadhesion therapeutics.

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.

Effect of two toothcleaning frequencies on periodontal status in patients with advanced periodontitis

OBJECTIVE

To compare the effect of once a day toothcleaning with once in 2 days toothcleaning in patients with advanced periodontitis.

MATERIAL AND METHODS

Twenty-two patients, aged 34-54 years were given intensive oral hygiene (OH) and half their mouth root planed with re-assessment 6 weeks later. The patients were randomised into either a once a day toothcleaning group or a once in 2 days toothcleaning group. The effects of the two cleaning regimens were assessed during a 6-week follow-up period. Two patients were excluded from the study. Analysis of covariance was used to test the difference between the two groups at baseline and at 6 weeks.

RESULTS

There was a statistically significant difference between the two groups in plaque reduction (p=0.01) and reduction of probing pocket depth >6 mm (p=0.05) in the OH-only sites. No significant difference was found between the two cleaning regimens in the combined oral hygiene with root planing sites.

CONCLUSION

The present study demonstrated that in patients with advanced periodontitis, once a day toothcleaning is more effective than once in 2 days toothcleaning in otherwise untreated sites.

Plaque development in relation to the periodontal condition and bacterial load of the saliva

AIM

To investigate the influence of the oral bacterial load on plaque development in various groups of periodontitis patients and in healthy subjects.

MATERIAL AND METHODS

This study included subjects with a healthy periodontium, a healthy reduced periodontium after treatment, an inflamed reduced periodontium after treatment and untreated periodontitis. At the start of the study, subjects were instructed to rinse with 10 ml reduced transport fluid (RTF) for 10 s in order to evaluate the oral bacterial load. The microbiological evaluation included anaerobe culture and phase-contrast microscopy. Next, the amount of plaque and the clinical condition were evaluated. Thereafter, all supragingival plaque was removed and patients were instructed to refrain from all oral hygiene procedures for 19 h. Subsequently, the rinsing procedure and the evaluation of the amount of plaque were repeated.

RESULTS

The amount of plaque that developed in 19 h was significantly higher in the untreated periodontitis group as compared with the two healthy groups. In case of an inflamed reduced periodontium, sites with deep pockets developed more plaque in 19 h than sites with shallow pockets. The number of bacteria present in the rinsing samples of the two inflamed groups was considerably higher than of the two periodontally healthy groups. A significant correlation was found between the bleeding index at intake and the plaque index at 19 h. No correlations were found between gingival recession and the bacterial counts at intake, and the plaque index at 19 h.

CONCLUSION

The present findings support the concept that the periodontal condition is the dominating factor in relation to the rate of plaque formation. The number of bacteria present in the oral cavity as ascertained by means of a rinsing sample does not seem to play a role.

Protein adsorption at polymer-grafted surfaces: comparison between a mixture of saliva proteins and some well-defined model proteins

Grafting a dense layer of soluble polymers onto a surface is a well-established method for controlling protein adsorption. In the present study, polyethylene oxide (PEO) layers of three different grafting densities were prepared, i.e. 10-15 nm2, 5.5 nm2 and 4 nm2 per polymer chain, respectively. The adsorption of different proteins on the PEO grafted surfaces was measured in real time by reflectometry. Furthermore, the change of the zeta-potential of such surfaces resulting from adsorption of the proteins was determined using the streaming potential method. Both the protein adsorption and the zeta-potential were monitored for 1 h after exposure of the protein solution to the surface. The adsorption pattern for a mixture of saliva proteins was compared to those observed for a number of well-defined model-proteins (lysozyme, human serum albumin, beta-lactoglobulin and ovalbumin). The results of the adsorption kinetics and streaming potential measurements indicate that the effect of the PEO layer on protein adsorption primarily depends on the size and the charge of the protein molecules. The saliva proteins are strongly blocked for adsorption, whereas the change in the zeta-potential is larger than for the other proteins (except lysozyme). It is concluded that positively charged protein molecules, having dimensions larger than those of lysozyme, are involved in the initial stage of adsorption from saliva onto a negatively charged surface.

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.

Comparative professional plaque removal study using 8 branded toothbrushes

BACKGROUND AND AIM

Considerable interest has been shown in the plaque removal properties of modern toothbrush designs. The primary aim of the study was to compare the plaque removal properties of 8 relatively recent designs of manual toothbrush using a professional tooth brusher and within a commonly used time frame. A secondary aim was established to utilise the data to observationally appraise plaque accumulation together with the patterns of removal as a consequence of using the timed professional tooth brusher.

METHOD

The method was an 8-period, single-examiner, randomized, blind cross-over study involving 24 healthy volunteers, balanced for residual effects. Subjects accumulated plaque over a 4 day no oral hygiene period. On day 4, the accumulated plaque was scored by plaque index at the mesial, mid and distal sites of each of the buccal and lingual surfaces of the assessed teeth. Subjects were then removed from the assessment area where they received a professional brushing timed to last 48 s. Brushing was completed according to pre-study training without toothpaste and was followed by a re-scoring of the remaining plaque. A washout period of 3 days was then allowed prior to the next period during which normal oral hygiene was resumed.

RESULTS

Similar quantities of plaque accumulated in each arch, although the difference between the buccal and lingual surfaces was of the order of 30%. The professional toothbrusher removed approximately 40% of the accumulated plaque in the 48 s allocated. The buccal surfaces were most effectively cleaned (approximately 45%) compared with the lingual (approximately 25%), with the plaque removal in the mesial and mid sections approaching 40% and 60% respectively. The difference in performance between the test brushes corresponded to 5% of the residual plaque values with none being significantly more efficient overall. Pair wise site comparisons did produce differences of the order of 10% (p=0.004) at the mesio-buccal, and 8% (p=0.030) at the mid-buccal sites respectively in favour of 2 brushes compared to one other brush.

CONCLUSIONS

These data derived from a standardized brushing method support the contention of many researchers that there is no one superior design of manual toothbrush. The minor and few site differences in favour of some brushes are unlikely to be of clinical significance to gingival health. This leaves uncontested the conclusion that the user is by far the most significant variable. Perhaps methods such as used in the present study could be more gainly employed to set a minimum standard of toothbrush efficacy.

Evaluation of the dentogingival area during early plaque formation

BACKGROUND

The aims of this investigation were to evaluate the pattern of supragingival plaque formation in the dentogingival area within 96 hours after abstinence from mechanical plaque control and to clinically analyze the gingival inflammatory response observed.

METHODS

Six male volunteers, 20 to 23 years of age, had their upper incisors and cuspids polished. Four independent periods of no mechanical plaque control--24, 48, 72, and 96 hours--were instituted. In each period, plaque was disclosed and standardized individual photographs were taken. Impressions were taken and replicas were analyzed by scanning electron microscopy. Gingival crevicular fluid (GCF) was collected at baseline and 96 hours. The height of the gingival papilla was measured at baseline, 24, and 96 hours.

RESULTS

Results showed the presence of a plaque-free zone (PFZ) along the gingival margin up to 72 hours. After 96 hours, there was a significant reduction in the presence of PFZ in the proximal thirds of the buccal surface when compared to the other experimental periods. At the end of the study, there was a significant increase in the GCF flow as well as edema of the interdental papilla, when compared to baseline values.

CONCLUSIONS

The PFZ observed during the initial phase was less apparent at the 96-hour period. At this time, there was an increase in the gingival inflammatory response, represented clinically by increased GCF flow and edema.

Compositional analysis of human acquired enamel pellicle by mass spectrometry

Relatively little is known about the formation of the acquired enamel pellicle other than that it involves the selective adsorption of specific proteins from oral fluids. Previous studies on the identification of pellicle components have relied largely on immunological or enzymatic detection and have been hampered by the fact that only minute quantities of pellicle can be removed from tooth surfaces. The present work describes an improved method of harvesting pellicle that combines mechanical and chemical removal; this approach was used to investigate systematically the desorption of in vitro pellicle components with different solutions. Eleven major in vitro pellicle proteins were identified by using a combination of electrophoretic separation and matrix-assisted laser desorption/ionization-reflectron time-of-flight mass spectrometry. A similar analysis of in vivo-formed pellicle revealed the presence of intact statherin, lysozyme, albumin and amylase. Further analysis of in vivo pellicle by liquid chromatography-electrospray ionization mass spectrometry suggested the presence of numerous low molecular-weight fragments of precursor proteins. The protein composition of in vitro whole-salivary pellicle adsorbed to hydroxyapatite and that of in vivo enamel pellicle differed for proline, the result of a reduction in the content of acidic proline-rich proteins in the in vivo samples. Unique features of the oral environment such as enzymatic activities or mineral surface properties may account for these differences between in vivo and in vitro pellicle formation.

Oral hygiene in the prevention of caries and periodontal disease

While some periodontal disease may be as old as mankind itself, caries as a public health problem appeared with the development of flour and sugar mills, and the universal access to fermentable carbohydrates. As a consequence, during the last 500 years caries and periodontal disease have been the most common diseases afflicting the human mouth. Together, these two diseases have been responsible for untold pain and suffering, and for excessive destruction and loss of people's teeth. With improving social circumstances in most industrialised nations, increased availability and affordability of modern oral health care, and the promotion of conservative treatment concepts, the 20th century saw significant progress in eliminating pain and tooth loss. Moreover, during the last 50 years advances in the oral health sciences and in technology, have not only increased our understanding of the nature of these diseases and their causes, but also introduced and tested new approaches to their prevention.

Reduced plaque accumulation on hydrocarbon thin film deposited on restorative acrylic polymers

The deposition of a thin polymeric film from ethylene plasma was used to modify the surface properties of acrylic teeth, commonly used in the dental practice for crown and bridge restorations. The effects of the surface modification process on the surface composition, morphology, and energetics were evaluated by electron spectroscopy for chemical analysis, atomic force microscopy, and contact angle measurement respectively. Plaque accumulation on the plasma-coated and untreated material was evaluated in in vivo experiments, in which the same patient received conventional and plasma-coated restorations. The hydrocarbon-like surface of the plasma-coated restoration remained remarkably free from plaque, even in the absence of brushing. On the other hand, plaque accumulation was observed on the unmodified restoration. Results are discussed according to recent theories on bioadhesive phenomena.

The influence of anatomic and iatrogenic root surface characteristics on bacterial colonization and periodontal destruction: a review

PERIODONTITIS IS A MULTIFACTORIAL infectious disease affecting primarily a subset of subjects and a subset of sites. Recent microbiological data have acknowledged that before disease progression can occur, a susceptible host and site are required, in addition to the presence of pathogenic bacteria. This review discusses factors affecting periodontal disease progression and focuses in particular on the influence of anatomic and iatrogenic root surface characteristics. Retrospective studies clearly suggest a strong association between anatomic aberrations and periodontal attachment loss. Cemental tear seems to have the potential to initiate an aseptic, rapid, site-specific periodontal breakdown in a non-infected environment, illustrating the complexity of the attachment loss process. Recent experimental findings, furthermore, demonstrate a significant influence of root surface instrumentation roughness upon subgingival plaque formation and gingival tissue reactions, as well as a significant and positive relationship between subgingival plaque accumulation and inflammatory cell mobilization. These results indicate that subgingivally located irregularities may form stagnant sites or ecological niches which favor both retention and growth of organisms. Such events in addition to the progressive inflammatory changes may critically influence the subgingival environment by turning a stable site into an unstable or active periodontitis site. Thus, local anatomic and iatrogenic root surface characteristics may have a more profound effect on gingival health than previously assumed, particularly on a site level.

Medications as risk factors for periodontal disease

As the United States population ages, people will be taking more medications which may benefit their general health but not necessarily their periodontal health. The effects of medications have been grouped into six categories as follows: behavioral alteration of oral hygiene methods, alteration of plaque composition, effect on gingival tissues, effect on alveolar bone, effect on gingival crevicular fluid, and effect on salivary flow. Although most medications discussed in this paper increase the risk for periodontal disease, a few may actually decrease the risk. These include the effect of phenytoin on alveolar bone, the antibacterial effect of antibiotics, the anticollagenolytic effects of tetracyclines, and the effect of non-steroidal anti-inflammatory drugs on decreasing alveolar bone resorption.

Root end filling materials: a review

When non-surgical attempts prove unsuccessful or are contraindicated, surgical endodontic therapy is needed to save the tooth. The procedure usually consists of exposure of the involved area, root end resection, root end preparation and insertion of a root end filling material. Numerous materials have been suggested as root end filling materials. This article is a review of the literature on the suitability of various root end filling materials based on their leakage assessment, marginal adaptation, cytotoxicity, and usage test in experimental animals and humans.

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

Three clinical trials were carried out to evaluate the effects of mouthrinses containing 5n-octanoyl-3'-trifluormethylsalicylanilide (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 x 4 days (study 1), 3 x 18 days (study 2) and 3 x 14 days (study 3). They rinsed, 2 x 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% salifluor 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.

Topographic distribution of subgingival plaque along root surfaces of human periodontally diseased teeth. A descriptive study

The purpose of this study was to characterize the topographical distribution and organization of subgingival plaque in periodontally diseased teeth. 26 extracted teeth were fixed and processed for undecalcified histological evaluation. The sections were cut perpendicular to the long axis of the tooth and analyzed by phase-contrast microscopy. The coronal portion of the analyzed roots showed a dense accumulation of filamentous forms, fusiform rods, coccoid forms and loosely aggregated spirochetes. The middle and apical portions showed a non-uniform distribution of the microflora, with microorganisms representing all the known morphotypes. Furthermore, plaque was detected below undisturbed periodontal fibers, indicating that plaque not only forms apically, but also in a lateral direction, penetrating and colonizing below areas where periodontal fibers are inserted into the root surface.

Effect of localized experimental gingivitis on early supragingival plaque accumulation

Previous investigations have reported increased plaque formation in the presence of gingival inflammation as compared with gingival health. In these investigations, experimental gingivitis has been induced by total abolition of oral hygiene such that increased levels of salivary bacteria could contribute to the increased plaque formation. In the present study, experimental gingivitis was localized to 2 selected teeth whilst maintaining normal oral hygiene measures in the rest of the mouth. The aim of this study was to investigate whether the mass of plaque accumulating in a 3-day period is influenced by the inflammatory status of the adjacent gingival margins. Following scaling, prophylaxis and a period of optimal hygiene to establish gingival health, "plaque-guards" were worn during routine oral hygiene performance to prevent any cleaning on the buccal surfaces of teeth 14 and 15 from days 0 to 3. On day 3, accumulated plaque was removed from a 1.5 mm zone on the buccal surfaces of 14 and 15 adjacent to the gingival margins and weighed immediately. Subjects continued to wear their plaque-guards during oral hygiene until day 14 to induce experimental gingivitis around the experimental teeth. At day 14, all plaque was cleaned from the buccal surfaces of the experimental teeth and the mass of plaque accumulating over the next 3 days weighed on day 17. Comparison of plaque weights showed that the wet-weight of 3 day-old plaque was higher in the presence of experimental gingivitis than in the presence of gingival health (p = 0.02). This observation suggests that the inflammatory status of the marginal gingiva has an important effect on early, supragingival plaque accumulation.

Influence of tooth instrumentation roughness on gingival tissue reactions

Histological studies have demonstrated a relationship between the amount of subgingival plaque and the magnitude and extension of gingival tissue reactions. The objective of the present study was to evaluate inflammatory reactions in the gingival tissues facing plaque accumulation at a diamond and curet-instrumented root surfaces. Experimental, deep periodontal defects were established at buccal surfaces of mandibular and maxillary canine teeth in 5 beagle dogs. The root surfaces were instrumented by a flame-shaped, fine-grained. rotating diamond point, or by a sharp curet. Next, the dogs were fed a plaque-inducing diet for 70 days. The animals were then sacrificed, and tissue blocks of the experimental sites including teeth, alveolar bone, and gingival tissues were secured. The gingival soft tissue was processed for histomorphometric analyses at 3 levels. Epithelium and connective tissue area measurements showed no differences between the two instrumentations. Junctional epithelium (JE) cell point counts exhibited a higher proportion of inflammatory cells (IC)in specimens facing diamond compared to curet-instrumented defects. A higher proportion of IC was present within the coronal compared to the apical aspect of the JE for both instrumentations (P < 0.05). A significant difference in IC density between instrumentations was detected for non-infiltrated (P < 0.05), as well as for infiltrated (P < 0.01) connective tissue. The infiltrated connective tissue (ICT) inflammatory cell density was significantly (P < 0.01) and positively correlated to the JE inflammatory cell density (r = 0.75), and to area measurements of ICT (r = 0.55). The overall results demonstrate that the character of subgingival root instrumentations significantly affects gingival inflammatory reactions, most likely by influencing subgingival plaque formation.

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

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 prophylaxis 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.

Microbial vitality of supragingival dental plaque during initial stages of experimental gingivitis in humans

Although vital plaque micro-organisms are part of the natural ecosystem in the oral cavity they are also the key factor in the development of diseases induced by the human dental plaque. In a previous study (9) the portion of vital bacteria related to the total number of plaque micro-organisms (i.e. the microbial vitality) appeared low in small plaque samples. The objective of this investigation was to determine the exact relationship of microbial vitality and age of supragingival plaque during the early phases of human dental plaque formation. Between intervals of optimal oral hygiene, thirteen participants refrained from all oral hygiene measures for periods of 1, 2, 4, 8, 24 and 72 h. Plaque was completely sampled from a defined area situated on the vestibular surface of the teeth 13, 14, 15, 23, 24 and 25. The pooled plaque from these areas was immediately processed. Total bacterial counts (BC) as enumerated by darkfield microscopy, and colony-forming units (CFU) were recorded. The microbial vitality was calculated indirectly as plating efficiency (PE = CFU per BC) and directly assessed using a vital fluorescence (VF) technique. In the 1 h old plaque samples the median values of PE and VF were 29% and 18%, respectively. Thereafter, the microbial vitality increased significantly with plaque age. The 24 h old plaque samples yielded values of 77% (PE) and 62% (VF). It was concluded that the microbial vitality of the early dental plaque investigated was considerably lower compared to that of a more mature plaque.

Microbial generation time during the early phases of supragingival dental plaque formation

The objective of this investigation was to determine the microbial generation time during early human supragingival plaque formation. On 2 occasions, 13 participants refrained from all oral hygiene measures for periods of 1, 2, 4, 8, 24 and 72 h. Plaque was sampled from defined areas of the teeth 13, 14, 15, 23, 24 and 25. Two independent methods were used to estimate the total number of viable cells: colony-forming units BCVF, total bacterial counts (BC) as enumerated by microscopic examination, and the percentage of vital bacteria using a vital fluorescence technique (VF) were recorded. The total number of vital microorganisms was calculated by BCVF (= BC x VF). The generation time based on either colony-forming units or BCVF increased significantly with plaque age. During the first interval (1-4 h), the microbial multiplication took slightly less than 1 h. After the establishment of a more mature plaque (24-72 h), the replicating time was between 12.5 h (BCVF) and 14.8 h (colony-forming units). It was concluded that the microbial generation time recorded at the initial stages of plaque formation is considerably lower than that found in older plaque.

Plaque formation at healthy and inflamed gingival sites in young individuals

The present investigation was performed to evaluate the influence of gingivitis on the amount of de novo plaque that forms during a 24-h period of no oral hygiene. 292 fully dentate subjects participated in the study. The condition of the gingiva and the presence of supragingival plaque were examined at 4 surfaces of each tooth at a baseline examination. Following this examination, the participants were subjected to a comprehensive mechanical tooth cleaning and instructed to refrain from tooth cleaning measures during the subsequent 24 h. The plaque examinations were repeated at the end of the 24-h period. The results from the clinical trial revealed that during a 24-h period of no tooth cleaning, subjects with naturally occurring overt gingivitis, in general, formed more plaque than young individuals with healthy gingivae. Furthermore, plaque in all parts of the dentition, formed more frequently on tooth surfaces adjacent to sites with gingivitis than at healthy sites. It was concluded that the condition of the gingiva plays an important role for de novo plaque formation.

The influence of gingival inflammation on de novo plaque formation

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 (PlI = 0.93 and 0.82) than at sites with GI > 0 (PlI = 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.

Copper plate replica SEM of developing dental plaque in monkeys (Macaca fascicularis)

The aim of the study was to examine the development of dental plaque in macaque monkeys (Macaca fascicularis). Copper plate replicas were constructed from impressions of the labial surface of one of the upper central incisor teeth after tooth cleaning and when plaque had accumulated for 12, 24 and 48 h in each of five animals. Scanning electron microscope examination of the replicas showed that bacteria were present on the tooth surface as scattered individual cells, which after 24 h had formed a continuous layer. Both coccoid and filamentous bacteria were visible in 48-hour-old plaque. Such a rapid accumulation of potentially periodontopathic dental plaque emphasizes the importance of regular and meticulous oral hygiene.

Dental bacterial plaques. Nature and role in periodontal disease

Antony van Leeuwenhoek first described oral bacteria. However, not until almost 200 years later was the famous Koch postulate introduced. Since then, research has extensively been performed regarding the development and microbiology of dental plaques. In spite of the complexity of the developing flora of supragingival plaque, culture studies have shown a remarkably orderly succession of organisms. Lately, the concept of microbial specificity in the etiology of periodontal diseases has been widely suggested, i.e., that different forms of periodontal disease are associated with qualitatively distinct dental plaques. Cross-sectional and longitudinal studies of the predominant cultivable microflora reveal that only a small number of the over 300 species found in human subgingival plaques are associated with periodontal disease. Among the commonly mentioned are: Actinobacillus actinomycetemcomitans, Bacteroides gingivalis, Bacteroides intermedius, Capnocytophaga sp., Eikenella corrodens, Fusobacterium nucleatum, and Wolinella recta, as well as certain gram-positive bacteria such as Eubacterium species. Anti-infective therapy for many systemic infections equals the use of antimicrobial drugs. However, for localized infections like periodontal diseases, treatment may consist of a combination of mechanical wound debridement and the application of an antimicrobial agent. The general effectiveness of mechanical anti-infective therapy and successful oral hygiene in the management of periodontal disease is well established in the literature and has met the test of success in clinical practice for most cases of periodontitis in adults. The definition of periodontal pathogens as either opportunistic pathogens, or as exogenous pathogens carries with it significant implications.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of gingival inflammation, tooth type, and timing on the rate of plaque formation

The undisturbed supragingival plaque formation was recorded twice over a 100 hours period in 14 healthy dental students; first after induction of gingival inflammation and a second time starting from a healthy gingiva. During each experimental segment plaque formation was recorded on 42 randomly selected and clean teeth at the start and after 6, 12, 24, 30, 36, 48, 54, 60, 72, 84, and 96 hours. Four hours later all teeth up to the first molars were examined. The presence of disclosable plaque was calculated planimetrically as percent of the total labial surface area of the tooth. The rate of plaque formation was found to be significantly greater (P = 0.001) in the presence of gingival inflammation (+ 29.0%). Moreover, this study indicates an important variation in the plaque growth rate within the dentition; the highest scores were found for the upper premolars, the upper molars, and the lower front teeth. Finally, the rate of plaque formation was found to decrease during the night.

Discriminating power of five plaque indices

Since plaque plays a major role in the development of periodontal inflammation, special attention is paid to its composition and quantity. Several indices have been designed for the quantification of the supragingival plaque. The aim of the present study was to compare the utility and discriminating power of five such plaque indices. In 14 subjects, three teeth were selected randomly on which the undisturbed plaque formation was studied over a period of 96 hours. This examination was performed twice, the first time after induction of gingivitis and a second time starting with a healthy gingiva. It is known that in the presence of gingival inflammation, the plaque growth rate slightly increases. Plaque formation was estimated at several visits with the following indices: Harrap index, Quigley and Hein index, Navy index modified by Clemmer and Barbano, Navy index modified by Hancock and Wirthlin, and a planimetrical plaque scoring system. The path of the plaque growth curve was found to depend on the selected plaque index, going from an exponential curve (planimetry) over an sigmoidal curve (Harrap index, Navy index modified by Hancock and Wirthlin) to a nearly linear relation (Quigley and Hein, Navy index modified by Clemmer and Barbano). By comparing the plaque scores on patients with healthy gingiva with those from patients with inflamed gingiva, it was found that the planimetrical plaque index had a clearly higher discriminating power. It was concluded that the choice of an index for the measurement of the plaque extension depends on the goals of the study.

Secretory IgA adsorption and oral streptococcal adhesion to human enamel and artificial solid substrata with various surface free energies

In this paper, secretory IgA adsorption from a single component sIgA solution and from human whole saliva onto human enamel and artificial solid substrata with various surface free energies was studied as a function of time. ELISA indicated that screening or displacement of adsorbed sIgA by other salivary proteins occurred only on low surface free energy substrata, not on high surface free energy substrata such as enamel. In addition, the adhesion of three oral streptococcal strains (Streptococcus mitis BMS, S. sanguis 12, and S. mutans NS), also having widely different surface free energies, to sIgA-coated surfaces was studied. The adhesion of all three streptococcal strains was significantly reduced in the presence of a sIgA coating. However, ranking the adhesion data with respect to the various substrata revealed a similar order to that in the case of uncoated substrata, indicating that substratum properties were at least partly transferred by the adsorbed protein film to the interface with adhering micro-organisms. For S. sanguis 12 and S. mitis BMS, adhesion decreased proportionally with the amounts of sIgA detected by ELISA, but for S. mutans NS such relations with the amounts of sIgA detected on the protein-coated substrata were not found. Thus, for S. mutans NS a specific antibody effect seems to exist in addition to a non-specific protein effect like that observed for S. sanguis 12 and S. mitis BMS.

Scanning electron microscopic investigation of changes in the dentogingival area during experimental gingivitis

The purpose of this study was to investigate the changes that occur in the dentogingival area during experimental gingivitis using a replication technique and scanning electron microscopy (SEM). The upper 1st premolars of 20 subjects were examined prior to plaque accumulation, after plaque had become clinically visible and after 3 weeks plaque accumulation. 3 distinct zones were examined: the tooth surface and its integuments, the gingival crevice and the oral gingiva. Surface features such as perichymata, pits, depressions and cracks were rapidly covered by plaque deposits. These had a raised globular surface with occasional embedded desquamated epithelial cells. Raised plaque colonies were frequently seen by the end of the study. Initially, the gingival crevice presented a layered undulating appearance. With plaque accumulation many desquamating epithelial cells were seen and variations occurred in the width of the crevice. These changes were mirrored in the oral gingiva. The junctional epithelium was initially smooth with occasional pores and emigrating leucocytes. As plaque accumulated, the presence of pores and leucocytes increased and considerable disruption by desquamating epithelial cells was noted. No subject proved resistant to the influence of plaque-induced changes.

[Scanning electron microscopic research on the clinical use of interdental stripping]

The morphology of approximal enamel that has been stripped for therapeutic reasons was evaluated under the scanning electron microscope (SEM) twelve weeks and one year after treatment. In part one of the study the teeth were extracted before evaluation, in the second part replica were taken. For comparative reasons the morphology of the natural approximal enamel surface was evaluated under the SEM, too. After twelve weeks the edges of the furrows were seen to be smoother and plaque accumulations were found in the depths of the furrows. One year after there was found essentially no difference. In some of the specimens there was found a certain levelling of the edges in the approximal contact area, but not in the cervical region of the artificially abraded tooth surface. The natural enamel surface of the contact area showed excavations of similar size as the furrows that remain after stripping and finishing. But our study shows that the therapeutic approximal abrasion leaves furrows in the cervical region that even after one year had not undergone repair. The question is discussed, if thus predispositions for periodontal pathologies and caries could be created.

A rationale for comparison of plaque-retaining properties of crown systems

The sequence of the initiation, formation, development, and maturation of dental plaque was reviewed. The gingival response to plaque formation was identified to control plaque growth for prolonged gingival health. A strong implication has been established between rough, overcontoured metal ceramic restorations and periodontal disease. Unsightly soft tissue around crowns result from increased plaque accumulation. In comparing esthetic crowns, three critical variables are considered. The factors that mediate plaque accumulation and influence gingival health at the tissue-restoration interface are (1) surface roughness, (2) marginal fit, and (3) contour. Minimizing plaque accumulation is crucial for gingival health.

[The results of scanning electron microscopy research on interdental stripping in vitro]

In an in-vitro study the abrasive qualities of different orthodontic finishing strips were evaluated on the enamel surfaces of human teeth by means of a scanning electron microscope. As a result we can state that even the use of the finest finishing strip cannot eliminate the deep furrows that resulted from prior abrasion with a strip that is more coarse. The remaining furrows caused by the abrasive procedure are so deep and wide, that plaque accumulation may well be expected therein, and thus be predisposing for caries and periodontal pathology.

The effects of pellicle formation on streptococcal adhesion to human enamel and artificial substrata with various surface free-energies

The influence of a pellicle on streptococcal adhesion was studied. A "ripened" two-hour salivary pellicle and an "early" five-minute salivary pellicle were formed on human enamel and artificial solid substrata with varying surface free-energies. Three strains of oral streptococci, also with widely different surface free-energies, were used for adhesion studies. Pellicle formation and streptococcal adhesion took place at a constant shear rate of 21 s-1. Adhesion of S. mitis BMS to bare and pellicle-covered enamel was low and not significantly affected by the presence of a pellicle (0.7 x 10(6) and 0.6 x 10(6) cells.cm-2, resp.), whereas the numbers of S. sanguis 12 and S. mutans NS adhering to bare enamel (4.2 x 10(6) cells.cm-2 and 13.8 x 10(6) cells, cm-2, resp) were significantly reduced by the presence of a pellicle. This reduction was almost complete after only five minutes of salivary protein adsorption (1.9 x 10(-6) and 1.1 x 10(6) cells.cm-2 for S. sanguis and S. mutans, resp.) but further reduced for S. sanguis adhering to a ripened pellicle (0.7 x 10(6) cells.cm-2). The numbers of streptococci adhering at equilibrium to bare enamel could be fitted to a thermodynamically based model, which was previously described for bacterial adhesion to homogenous artificial substrata. Streptococcal adhesion to artificial substrata exposed to saliva was low, and the differences among uncoated materials were markedly reduced even after only five minutes' exposure to saliva.

Plaque accumulations caused by interdental stripping

Human enamel surfaces were stripped with orthodontic grinding and finishing materials, and evaluated with the scanning electron microscope (SEM). Even under in vitro conditions with the finest finishing strips, it was not possible to produce an enamel surface free of the furrows that result from the initial abrasion caused by the coarse strip. Enamel surfaces stripped gradually from coarse to superfine were left in the mouths of patients for 12 weeks and evaluated with the SEM. The edges of the furrows were found to be smoother but the furrows remained wide and deep enough to facilitate more plaque accumulations than those on untreated surfaces. The use of dental floss did not result in prevention of plaque accumulations along the bottom of the furrows.

Scanning electron microscopy of early microbial colonization of human enamel and root surfaces in vivo

This study describes the pattern of microbial colonization in six dental students, who carried test pieces of enamel and root surface in intraoral acrylic appliances for 4, 8, 12, 24, and 48 h, respectively. Oral hygiene was discontinued during the experimental periods. The results showed that oral microorganisms colonized enamel and root surfaces individually. The pattern of colonization mimicked the surface structure of the tooth; on enamel surfaces the first bacteria appeared in pits and surface irregularities followed by proliferation along the perikymata, while on root surfaces bacterial colonization was characterized by a haphazard distribution. Within the initial 24-h period root surfaces were more heavily colonized than were enamel surfaces. This pattern was characteristic irrespective of differences in the intra- and interindividual rates of bacterial coverage. It is concluded that early microbial colonization in vivo is determined by the surface structure of the tooth. Consequently, natural tooth surfaces should not be replaced by artificial surfaces in structural studies of microbial deposits in the oral cavity.

Rate of plaque formation--some clinical and biochemical characteristics of "heavy" and "light" plaque formers

The purpose of the present study was to give a clinical and biochemical characterization of two groups of individuals with different rates of plaque formation. From 133 individuals, 9 "heavy" and 10 "light" plaque formers were selected. The mean plaque index after 3 days of plaque accumulation, on buccal surfaces of premolars and first molars, was 2.6 for the "heavy" and 0.6 for the "light" plaque formers. The following variables were determined: periodontal status, DFS, dietary habits, salivary secretion rate and buffer effect, S. mutans and lactobacillus counts in saliva, salivary content of IgA, lactoferrin, lactoperoxidase and lysozyme, saliva-induced aggregation of certain oral streptococci, gel electrophoresis of saliva, amino acid composition of saliva and the acquired pellicle and retention depth of the dentogingival area. Comparing the two groups of plaque formers, statistically significant differences were found for the following three variables: parotid saliva-induced aggregation of a strain of S. sanguis, content of glutamic acid in the acquired pellicle and retention depth of the dentogingival area for maxillary premolars. Large variations for all studied variables were found, both within and between the groups. Several factors may be involved in plaque formation and none of the studied variables alone could explain the large difference in the amount of plaque formed after 3 days between the "heavy" and "light" plaque formers.

Evaluation of replica techniques for the surface ultrastructure of rodent and human palatal mucosa

Two replicating techniques currently used for scanning electron microscopy were investigated qualitatively and quantitatively. The most accurate and reliable replicating material was an epoxy resin; this was superior to copper plating as the model material, despite some dimensional inaccuracies. The selected method was then used to obtain accurate elastomeric replicas of rodent and human palatal mucosa. Salivary-duct openings, epithelial cell boundaries, desquamating cells and cell-surface micropits were identified. In some areas, coccal organisms could be seen colonizing the epithelial surface.

The early bacterial colonization of acrylic palates in man

Adhesive tape applied to the fitting surface was used to study the early colonization of acrylic palates in six subjects. Streptococci were major constituents of the plaque accumulated on the tape over the first 3 days. Bacterial colonization of the tape discs was selective in that dextran-producing streptococci constituted a greater proportion of the total streptococcal count after 15 min compared with that of the initial sample and saliva, while the converse was true for Streptococcus salivarius. Scanning electron microscopy showed that denture plaque development started in grooves and depressions on the surface of the tape, and became more extensive with time. Comparison of the colonization of tape and acrylic discs in one individual demonstrated that the tape was a suitable model for in vivo colonization of dentures or orthodontic appliances.