The possibility of measuring plaque growth in vivo within 24 hours

Digital plaque monitoring: An evaluation of different intraoral scanners

OBJECTIVES

Intraoral scanners (IOS) display disclosed plaque, and the scientific literature has reported that plaque levels can be monitored on intraoral scans using one IOS system (Dexis 3800; control IOS). This study aimed to investigate whether this is also possible with other IOS systems (i700, Primescan, Trios 5; test IOS).

MATERIALS AND METHODS

Ten participants (29.6 ± 5.5 years) were enrolled. After plaque accumulation and subsequent toothbrushing, intraoral scans were performed with the control IOS and the three test IOS. All scans were aligned and the vestibular/oral surfaces of the Ramfjord teeth (16, 21, 24, 36, 41, 44) were analysed with automated planimetry using a predefined threshold value. The proportion of pixels assigned to plaque-covered areas was expressed as a percentage of the total number of pixels (P%). We then assessed whether the planimetrically determined plaque-covered areas corresponded to those identified visually. This revealed that a threshold correction (P%corr) was required for approximately 20 % (i700 and Trios 5) to over 65 % (Primescan) of the images.

RESULTS

Bland-Altman analysis showed no significant systematic bias and limits of agreement ranging from approximately -20 to +20 P% units, with a tendency towards lower values at higher plaque coverage. Manual correction improved the agreement and halved the limits of agreement. All test IOS could detect a reduction in plaque after brushing, as well as the typical site-dependant plaque distribution patterns.

CONCLUSIONS

All test IOS appeared to be suitable for plaque monitoring. Planimetric methods must be adapted to the colour representation of the IOS.

CLINICAL SIGNIFICANCE

Plaque monitoring using IOS opens a new field of application in preventive dentistry.

Visualization of dental plaque with a 3D-intraoral-scanner-A tool for whole mouth planimetry

Planimetry is a reliable method for detecting and monitoring plaque. Until now, this method has mainly been applied to conventional-camera images, which is difficult and time-consuming in relation to the entire dentition. Today, 3D-intraoral-scans are well suited for imaging the entire dentition and are therefore an efficient and feasible alternative. 3D-intraoral-scans have already proven successful for the quantification of plaque based on a plaque index. Therefore, aim of this study was to investigate whether images from 3D-intraoral-scans are also suitable for valid planimetric plaque measurements and monitoring; intraoral-camera images served as a reference. Twenty subjects (27.5±1.2 years) were included. Plaque was disclosed at three different time points: habitual plaque (T1), after 72 h without oral hygiene (T2) and after subsequent tooth brushing (T3) and quantified using 3D-intraoral-scans and intraoral-camera images (intraoral-camera CS 1500, intraoral-scanner CS 3600; Carestream Dental, Germany). The percentage of the plaque-covered surface of the total surface area (P%) was determined with a software specially programmed for this purpose using images from 3D-intraoral-scans of the oral and vestibular surfaces of the Ramfjord teeth (16, 21, 24, 36, 41, and 44); the intraoral-camera images of the vestibular surfaces of 16 and 36 served as reference. P% from images of the 3D-intraoral-scan and the intraoral-camera revealed a very good correlation (r = 0.876; p ≤ 0.001); the Bland-Altmann analysis showed a good agreement with no proportional and a very minor systematic bias with slightly higher values from images of the 3D-intraoral-scan. Further, P% measurements of the images of the 3D-intraoral-scan were able to detect changes in plaque levels, showing a 47% (p ≤ 0.001) increase in P% from T1 to T2 and a 43% (p ≤ 0.001) decrease after toothbrushing (T3). Planimetry using images of the 3D-intraoral-scan seems to be a suitable tool for whole mouth planimetry to record and monitor dental plaque.

Comparison of Quantitative light-induced fluorescence-digital (QLF-D) images and images of disclosed plaque for planimetric quantification of dental plaque in multibracket appliance patients

The purpose of the present cross-sectional clinical study was to check the ability of plaque detection and quantification by QLF-D against conventional digital photographs of disclosed plaque in multibracket appliance (MB) patients. 20 patients were included according to the following criteria: (1) upper and lower jaw treated by MB appliance, (2) patients being 16 years of age or older, (3) all central and lateral incisors as well as canines in situ, (4) absence of developmental defects, carious lesions, surface fillings, prosthetic restorations or recessions greater than 1/3 of root length in central/lateral incisors and canines as well as (5) declaration of consent. QLF-D and conventional photographs were analyzed planimetrically regarding plaque coverage on buccal and oral surfaces of central/lateral incisors and canines. The conventional photographs of stained plaque served as gold standard. On average, in QLF-D pictures 20.7% ± 17.4 of the tooth surfaces were covered with plaque, while the conventional photographs of disclosed plaque presented a mean plaque-covered area of 36.2% ± 23.5. The Bland-Altman plot for both imaging modalities showed a very large inconsistent scattering with both negative and positive deviations. The method discrepancy increased with increasing plaque coverage, thus indicating a systematic method error. On average, the deviation of the methods from the optimal line of accordance was -15.5%. In patients wearing MB appliances, there was no clinical significant agreement regarding the plaque-covered tooth surface depicted by QLF-D respectively conventional images of disclosed plaque. Due to the large method discrepancy, QLF-D is currently not reliable for precise plaque quantification in MB patients.

Short-term anti-plaque effect of two chlorhexidine varnishes

BACKGROUND

Chlorhexidine (CHX) varnishes have been mainly used for the prevention of caries in high-risk populations. Reports regarding their anti-plaque effect on a clinical level are limited to non-existing as opposed to their microbiological impact on plaque formation.

AIM

The aim of this preliminary investigation was to evaluate the anti-plaque effect of two CHX varnishes applied on sound enamel in relation to a positive control, a negative control and to one another.

METHODS

Sixteen healthy subjects volunteered for this randomized-controlled, single-blind, four-treatment-four-period crossover-designed clinical trial. A 3-day plaque re-growth model was used to determine de novo plaque accumulation following CHX rinsing, Cervitec application, EC40 application and no therapy. The amount of plaque was measured using the Quigley and Hein plaque index and "automatic image analysis" (AIA).

RESULTS AND CONCLUSIONS

Varnish treatment resulted in significantly higher plaque levels than CHX rinsing irrespective of the varnish that was used (p< or =0.002), implying that the latter is likely to remain the gold standard as an anti-plaque agent. However, highly significant differences were also found in favour of both varnish systems when compared with no therapy (p<0.001), which indicates that varnish treatment is an effective means of inhibiting plaque formation in a short time span. Cervitec exhibited slightly, yet significantly, higher plaque levels in comparison with EC40 as determined by AIA (p=0.006). Large-scale trials with a longer observation period are necessary to substantiate these results.

Quantification of dental plaque on lingual tooth surfaces using image analysis: reliability and validation

AIM

The aim of this study was to increase the versatility and further validate the method reported by Smith et al. (2001) by testing the reliability of plaque measurement against two well-known dental plaque quantification methodologies using image analysis in a clinical trial.

METHOD

The teeth of 40 subjects were disclosed before digital images of the labial and lingual surfaces of their upper and lower incisors were acquired. The amount of plaque present was quantified using a modification of the method described by Smith et al. (2001). The method was modified for obtaining images of the lingual surfaces by incorporating the use of orthodontic occlusal mirrors and 5-mm pieces of moistened blue articulating paper used to enable calibration. Plaque measurements were made from 320 upper and lower anterior teeth from the 40 subjects by two operators. Fliess' coefficient of reliability was used to assess intra- and inter-operator reliability and the independent sample t test was used to assess statistical significance between test and control groups after checking the data for normality. For validation, measurements were recorded using the Turesky et al. (1970) (modification of the Quigley & Hein (1962) plaque index and the Addy et al. (1983) plaque area index. The results were compared with the image analysis method using Pearson's correlation coefficient.

RESULTS

The results for reliability were within Fliess' range of "excellent" for both intra-operator repeatability and inter-operator reproducibility. Pearson's correlation coefficients showed highly significant values indicating the close similarity between all three methods.

CONCLUSIONS

This method for the measurement of dental plaque on lingual surfaces of anterior teeth proved reliable. The combined results from the labial and lingual surfaces of anterior teeth using image analysis produced trial conclusions comparable with the alternate plaque quantification methods used, with less clinician time and further producing a permanent database of images for future use.

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.

Intra-examiner reproducibility of 4 dental plaque indices

BACKGROUND, AIMS

The aim of the present study was to assess the intra-examiner reproducibility for 2 established ordinal plaque indices and 2 newly proposed interval plaque indices.

METHOD

15 subjects received a professional tooth cleaning and interrupted all oral hygiene measures for 48 to 62 hours. Plaque accumulation was scored 2x for all canines, premolars and 1st and 2nd molars in the 1st and 3rd quadrants with the visual plaque index (VPI), the modified navy plaque index (mNPI), the axial plaque extension index (APEI) and the proximal plaque extension index (PPEI). 147 teeth (57 molars, 60 premolars, 30 canines) were scored.

RESULTS

No statistically significant differences were found for duplicate measurements with all indices, except for buccal and lingual VPI (p < 0.05. Wilcoxon test) and for buccal APEI (p < 0.01, t-test). High correlations existed between all duplicate measurements with r-values ranging from 0.76 to 0.94. For the VPI, 78% of buccal (kappa = 0.70) and 89% of lingual (kappa = 0.75) scores were identical, whereas this was the case for 88% of buccal (kappa = 0.81) and for 73% of lingual (kappa = 0.62) mNPI scores. For APEI and PPEI scores a linear regression was found with slopes ranging between 0.76 and 1.00. For these indices, the mean measurement error ranged between 0.4 and 9.1%. Results were comparable for VPI, mNPI and PPEI, whereas APEI appeared slightly less reproducible.

CONCLUSION

In conclusion, a high intra-examiner reproducibility was found for all plaque indices tested, both the ordinal and the interval indices.

Scanning electron microscopy of microbial colonization of 'rapid' and 'slow' dental-plaque formers in vivo

The aim was to investigate the morphological features of supragingival plaque development in 'rapid' and 'slow' plaque formers using scanning electron microscopy (SEM). Forty-nine healthy volunteers were screened for their plaque-formation rate after 3 days of oral hygiene abstinence using the Plaque Index (PI). Five with the highest and six with the lowest mean PI were selected as 'rapid' and 'slow' plaque formers, respectively. Six enamel blocks measuring 2 x 2 x 1 mm were bonded onto the buccal surfaces of the upper left canine, premolars and first molar of each selected participant after a series of prophylaxes and oral hygiene instruction to ensure clinical gingival health. A 14-day period with no oral hygiene began thereafter. An enamel block was removed at 3 hr, 6 hr, 1 day, 3 days, 7 days and 14 days from each individual, fixed, and processed for SEM. Quantitatively, more bacteria were observed on the 3-hr to 1-day enamel blocks of the 'rapid' plaque formers. The day-1 specimens of the 'rapid' group showed a more complex supragingival plaque structure than those of the 'slow' group. From days 3 to 14, during the maturation period of supragingival plaque, there were no discernible differences between the two groups except that intermicrobial matrix was more prominent in the 'rapid' group. In general, the development of supragingival plaque followed known patterns. These observations indicate that morphological features of supragingival plaque in 'slow' and 'rapid' plaque formers differ, especially in the early developmental phases.

Efficacy on supragingival plaque control of cetylpyridinium chloride in a slow-release dosage form

To evaluate the relative efficacy of a non-degradable osmotic slow-release dosage form containing 6.6 mg cetylpyridinium chloride (MOTS [Mucosal Oral Therapeutic System] CPC) to inhibit new plaque formation and gingivitis, a single-blind, randomised, parallel group pilot study was set up. 52 healthy volunteers were assigned to receive one of the following treatments for 18 days of non-brushing: holding 1 MOTS CPC 2 x daily for 2 h intra-orally, or rinsing 30 s with 15 ml Peridex 2 x daily, or dissolve Cepacol (each 1.6 mg CPC) lozenges 2 x daily unsupervised. Before the test period, the subjects received a thorough tooth cleaning followed by tooth polishing 1 x a week for 3 weeks to achieve clinical gingival health. After the start of therapy, the subjects were examined at day 4, 7 (+/- 2), 14 (+/- 2) and 18 (2 +/-). Relative efficacy was assessed by the modified Navy plaque index, the Quigley and Hein index, the planimetric plaque index, as well as the papillary marginal gingival index. There was an increase in both plaque formation and gingivitis over the 18 +/- 2 day period of nonbrushing for all subjects in the study. Peridex was the most effective in inhibiting plaque and gingivitis formation over that period of time. There was no difference between MOTS CPC and Cepacol at any time point in plaque accumulation and gingivitis intensity. Peridex was considered more convenient than MOTS CPC. Cepacol resulted in more staining at 18 days than MOTS CPC and Peridex.

Effect of a new pre-brushing rinse on dental plaque removal

Non-prescription prebrushing rinses to facilitate dental plaque removal have been advertised in recent years. The purpose of the present study was to determine the plaque removal effectiveness of Plax (Colgate) prebrushing rinse by comparing it to a placebo solution. 19 dental students volunteered for this double blind study which consisted of 2 experimental periods. The following procedure was followed: 3 weeks after scaling and polishing, the participants abstained from oral hygiene for 3 days to allow dental plaque to accumulate. After plaque disclosing, the 4 mandibular incisors were photographed using a strictly defined technique, as described by Quirynen et al. Then the volunteers mouthrinsed for 30 s with 15 ml of a solution provided to them. Neither the volunteers nor the examiners knew which solution (test or control) was used. After mouthrinsing, the participants were allowed to brush their teeth and the remaining plaque was photographed again. During the 2nd experimental period, the same procedure was followed, and the 2nd solution was used for mouthrinsing. The effectiveness of the solutions was evaluated by comparing the proportion of dental plaque removed during the 2 experimental periods. The area of dental plaque was measured by an electronic high-precision device (planimeter). The proportion of plaque removed after rinsing with Plax was 0.40 +/- 0.23 and after rising with placebo 0.42 +/- 0.24, of the tooth surface (p = 0.962). Analysis of data by means of paired t-test between the 2 experimental periods revealed no beneficial effect regarding plaque removal when Plax was used.

Relationship between bacterial counts, microbial vitality and the accumulation of supragingival dental plaque in humans

Comparisons between plaque index (PlI) and bacterial counts have been made already; however, these did not take into account the area used for plaque sampling. The objective of the present study was to determine the correlation between the PlI score, the number of bacteria and the bacterial plaque vitality when dental plaque was repeatedly sampled from the same area in each subject during early plaque accumulation. Between intervals of optimal oral hygiene, 10 participants refrained from all oral hygiene measures for periods of 1, 2, 3, 4 and 5 days. The PlI was recorded on the vestibular surface of all first premolars as local PlI:LS. For statistical reasons, the scores of the independent variable LS were added for each subject giving LS* values ranging from 0 to 8. The plaque sampled from this specific surface was circumscribed by the marginal gingiva and an acrylic splint, giving reproducible areas for plaque collection. Total microscopic bacterial counts (BC), colony forming units of anaerobes (CFUan) and aerobes (CFUae), and proportions of vital bacteria (VF) were compared with LS* values. BC and LS* values were strongly correlated. CFUan and CFUae increased significantly with LS*, but this increase was higher for LS* 0 to 4 than for LS* 4 to 8. The ratio between vital and dead microorganisms, assessed by two different methods, was low when an LS* of 0 was recorded, with higher ratios registered for LS* values 4 and 8.

Comparative antiplaque activity of sanguinarine and chlorhexidine in man

This clinical investigation examined the effect of a sanguinarine extract on bacterial plaque growth in man. Three different mouthrinses were examined: (i) Veadent containing 0.03% sanguinarine and 0.2% zinc chloride (test rinse); (ii) a vehicle solution containing all the excipients of Veadent except the 0.03% sanguinarine (control rinse); (iii) Hibident a 0.2% chlorhexidine digluconate formulation (positive control rinse). The trial in which 12 dental students participated, was designed as a single-blind, cross-over study. During 3 experimental periods of 18 days, the participants refrained from mechanical oral hygiene and rinsed twice a day with one of the above mentioned solutions. Between experimental phases, a wash-out period of 11 days was instituted. In each subject, 4 teeth were randomly selected for assessment. Clinical evaluations were performed at days 1 (0, 4, 8, 12 hours), 2, 4, 11 and 18. The plaque on the buccal surfaces of the selected teeth was disclosed with neutral red 0.05% and colour slides taken. The % of the tooth surface covered with plaque was calculated planimetrically from these colour slides. The present results show an excellent anti-plaque effect with Hibident, a very small effect with Veadent and a negligible effect with the vehicle solution without the sanguinarine. These findings would suggest that the Veadent mouthrinse would have at most only a limited role as a plaque inhibitor.

The influence of surface free energy and surface roughness on early plaque formation. An in vivo study in man

Previous in vivo studies suggested that a high substratum surface free energy (s.f.e.) and an increased surface roughness facilitate the supragingival plaque accumulation. It is the aim of this clinical trial to explore the "relative" effect of a combination of these surface characteristics on plaque growth. 2 strips, one made of fluorethylenepropylene (FEP) and the other made of cellulose acetate (CA) (polymers with surface free energies of 20 and 58 erg/cm2, respectively) were stuck to the labial surface of the central incisors of 16 volunteers. Half the surface of each strip was smooth (Ra +/- 0.1 microns) and the other half was rough (Ra +/- 2.2 microns). The undisturbed plaque formation on these strips was followed over a period of 6 days. The plaque extension at day 3 and 6 was scored planimetrically from color slides. Finally, of 6 subjects samples were taken from the strips as well as from a neighbouring smooth tooth surface (s.f.e. 88 erg/cm2; Ra +/- 0.14 microns). These samples were analysed with a light microscope to score the proportion of coccoid cells, and small, medium, and large rods or fusiform bacteria. At day 3, a significant difference in plaque accumulation was only obtained when a rough surface was compared with a smooth surface. However, at day 6, significantly less plaque was recorded on FEP smooth (19.4%) when compared with CA smooth (39.5%). Between FEP rough (96.8%) and CA rough (98.2%), no significant difference appeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Direct measurement of the bactericidal effect of chlorhexidine on human dental plaque

The purpose of the present study was to determine by means of a fluorescence test the ratio between vital and dead bacteria in dental plaque before and after 0.1% chlorhexidine rinses. Plaque was stained by fluoresceindiacetate (FDA), which gave a green color to the living micro-organisms, and by ethidiumbromide (EB), which introduced a red color into the nucleic acids of the dead bacteria. 1-, 2- and 3-day-old undisturbed plaque harbored 80 to 85% living micro-organisms. 1 h after chlorhexidine use, this % was reduced to a plateau of 19 to 34% of vital bacteria present in the sampled plaque. Between 6 and 8 h later, this % rose towards its original value. This study has shown that FDA/EB staining provides a method for direct measurement of bacteria vitality in dental plaque and, as such, can be of great value for testing the efficacy of various antiplaque agents.

Is early plaque growth rate constant with time?

Early plaque growth and plaque topography were studied in 15 young adults with a healthy periodontium during a 4-day period of no oral hygiene. After perfect tooth-cleaning, the recolonisation of the buccal surfaces of 48 teeth (front teeth and premolars) was recorded at the start and after 6, 12, 24, 30, 36, 48, 54, 60, 72, 84 and 96 h. At each visit, reproducible colour slides of the buccal tooth surfaces were taken after plaque disclosure. Plaque extension was calculated planimetrically as a % of the total surface area of the tooth. At the end of the experimental period, an average of 27.7% of the surface area was covered by plaque. The early plaque growth followed an exponential curve with a slight tendency for saturation at 96 h. During the night, the plaque growth rate decreased by up to 50%. Clear differences in plaque growth rate were observed between types of teeth, and the plaque growth pattern seemed to be closely correlated to irregularities of the tooth surface. The discontinuity in plaque growth and the influence from the tooth surface roughness have important implications for oral hygiene planning.

The influence of surface free-energy on planimetric plaque growth in man

The purpose of this study was to examine the change in plaque area over nine days in vivo on four materials with different surface free-energies (s.f.e.). Twelve healthy dental students participated in a cross-over, split-mouth, double-blind study. Supragingival plaque formation was recorded over a nine-day period, on four different materials: fluorethylenepropylene (Teflon) (FEP), parafilm (PAR), cellulose acetate (CA), and enamel (E) with s.f.e. of 20, 26, 57, and 88 erg/cm2, respectively. Strips made from the first three materials were stuck to the buccal surface of an upper incisor. The remaining incisor was carefully polished and served as an enamel surface. The increase in plaque was evaluated after three, six, and nine days. A planimetrical analysis was used so that the plaque area could be expressed as a percentage of the total buccal tooth surface. This procedure was repeated on each subject, so that at the end, each pair of central or lateral incisors received the four tested materials. The results indicated that the adherence of micro-organisms on pellicle-coated substrata was influenced by the material's s.f.e.; there was an association between the s.f.e. of the substrata and the supragingival plaque extension in vivo. High surface free-energy substrata in the oral cavity attracted more micro-organisms than did low energetic materials. Additionally, the bacterial adhesion seemed very weak on surfaces with a low s.f.e.

Plaque removing effect of a convex-shaped brush compared with a conventional flat brush

The plaque-removing effect of a convex-shaped multitufted brush was compared with that of a conventional flat multitufted brush. Two group (five and seven dental students, respectively), well instructed in the modified Bass technique, participated in a blind, splitmouth, crossover study during two consecutive experimental periods of 96 hours of undisturbed plaque growth. After each of these periods, a supervised brushing session was performed, followed by toothpick utilization. Plaque removal was evaluated using the modified Navy Plaque Index (MNPI) and planimetry. A 4% erythrosin solution was used as a disclosing agent. Planimetrically, the flat Oral B brush appeared significantly more effective than the convex shaped Ph brush (P less than 0.001). This superiority was even enhanced after the use of toothpicks (P less than 0.0005). The differences between the brushes, however, were too small to be detected by the less discriminating MNPI. Although it has been claimed that the convex brush could assure approximal plaque control, the results indicate that for the convex-shaped, as well as for the flat brush, an approximal aid is essential for good plaque control. The hypothesis that the design of the convex-shaped brush could facilitate the modified Bass technique for the average patient could not be proven in this study.