Comparison of various plaque parameters in individuals with poor oral hygiene

Interexaminer reproducibility of ordinal and interval-scaled plaque indices

BACKGROUND

Although many plaque scoring indices have been proposed for clinical or research purposes, only few of them are commonly used in the dental literature. Owing to the ordinal nature of these established indices, only nonparametric tests can be performed, while statistical analysts usually prefer parametric methodologies. Furthermore, these indices do not discriminate between the proximal and the broad surfaces of the teeth.

AIMS

The aim of this study was to assess the interexaminer reproducibility for one established ordinal plaque index and two recently proposed interval-scaled indices.

METHOD

Six subjects received a professional tooth cleaning and stopped all oral hygiene measures during 48-62 h. Accumulated plaque was disclosed and separately scored on all teeth except third molars by two examiners using the visual plaque index (VPI), the axial plaque extension index (APEI) and the proximal plaque extension index (PPEI). In total, 168 teeth (48 molars, 48 premolars, 24 canines and 48 incisors) were scored.

RESULTS

Statistically significant differences were found between the means of buccal VPI (p<0.05, Wilcoxon test), mesiobuccal, mesiolingual and distolingual APEI, and distobuccal, mesiolingual and distolingual PPEI (p<0.05, t-test). Spearman correlation values between the duplicate VPI measurements were 0.84 for buccal and 0.64 for lingual VPI, while Pearson correlation values varied between 0.51 and 0.83 for APEI and between 0.48 and 0.74 for PPEI. For VPI, 71% of the buccal (kappa=0.60) and 74% of the lingual (kappa=0.53) scores were identical. For APEI and PPEI scores, a linear regression was found with slopes ranging between 0.50 and 0.80. Mean measurement errors were 7.7% for buccal and 0.4% for lingual VPI, and ranged between 0.9% and 46.1% for APEI and PPEI.

CONCLUSION

The interexaminer reproducibility of all three indices showed fair to good agreement. Buccal VPI and buccal APEI in particular showed good agreement.

A plaque index for occlusal surfaces and fissures. Measurement of repeatability and plaque removal

Plaque indices have largely been developed for buccal and lingual tooth surfaces. There has been minimal interest in plaque accumulation on occlusal surfaces despite the predilection for caries at these sites. A numerical plaque index (0-5) is described based on the presence and distribution of plaque in the fissures and over the occlusal surfaces of permanent molar and premolar teeth. The repeatability of a single examiner in scoring the index was performed using 4 groups of 10 subjects. Each group of volunteers suspended tooth cleaning for 48 h and the index scored after disclosing plaque deposits. The index was rescored 60-90 min later. Plaque area was also determined by drawing the outline of plaque onto grids. Except for one condition of repeatability for one group, the 4 conditions of repeatability in scoring the index were met for all 4 groups of subjects. The sensitivity of the index and area recordings to detect plaque removed by brushing was then evaluated. A group of 10 subjects had plaque scored by index and area after suspending toothcleaning for 48 h. Subjects were then randomly allocated to brush or not brush their teeth and plaque rescored. The experiment was then repeated and brushing or not brushing crossed over. Highly significant differences between brushing and no brushing plaque indices and areas were determined. In conclusion, the occlusal fissure plaque index was easy to apply, repeatable and sufficiently sensitive to detect plaque removed by brushing. The index could find use as an additional measure of oral hygiene, in clinical trials on plaque control and possibly epidemiological studies relating to caries.

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.

Patterns and rates of growth of microcosm dental plaque biofilms

Rates of growth in wet weight and changes in them over time were established for microcosm dental plaques cultured from the mixed salivary bacteria in an artificial mouth. Standardized conditions included a continuous supply of medium containing 0.25% mucin and 1.5 ml of 5% w/v sucrose in 6 min every 8 h. Plaques were weighed daily. Plaque wet weight and total protein were highly correlated. Plaque doubling times were 3-7 h over day 1 and 9-21 h over day 2, which is similar to in vivo plaques. Subsequently, growth curves were either linear or between a linear and exponential increase. Evidence was obtained for plaque blooms. Methyl paraben (0.2%) applied for 15 min (3.75 ml) 6 times daily inhibited growth but only for 3 days, after which the rate was similar to control plaques, indicating that selection for resistance had occurred. It was concluded that the regulation of plaque growth rates is complex and does not conform to simple growth pattern models. Detailed studies of plaque growth and the effects of antiplaque agents can be carried out using this experimental system.

Comparability and discriminating power of 4 plaque quantifications

This study was designed for analysis of the discriminating power of 4 different quantifications of supragingival plaque: (1) plaque wet weight (PWW); (2) the plaque index (PlI); (3) the PLQ index measuring the coronal extension of plaque; (4) the area % of stained plaque. Different quantities of plaque were produced by adding chlorhexidine acetate (CHX), hydrogen peroxide (H2O2), or sucrose to experimental chewing gums. Total mean scores of 12 subjects in each of 3 test groups revealed that chewing of CHX gum resulted in the lowest plaque scores with all 4 quantifications and that the highest scores were recorded for the PWW or PlI of the sucrose gum users. Chewing of the H2O2 gum produced as much plaque as the sucrose gum when evaluated according to the PLQ index and exceeded the sucrose gum scores when evaluated according to the area % index. The PWW discriminated best between low, medium and high plaque scores after chewing of both CHX, H2O2 and sucrose gums. PlI scores 1 and 3 remained stable whereas the frequency of PlI score 0 strongly decreased and that of score 2 strongly increased when going from gums producing low (CHX) and medium (H2O2) to large (sucrose) amounts of plaque. The PLQ index discriminated well between low and medium but poorly between medium and large amounts of plaque. The area % index functioned well when subjects with low (CHX) and medium (H2O2) plaque scores were subgrouped into those with < 30%, 30-70% or > 70% of their tooth surfaces covered with stained plaque.(ABSTRACT TRUNCATED AT 250 WORDS)

Computerized planimetric method for clinical plaque measurement

A computerized planimetric method for plaque area measurement has been developed. Using a computerized image analysis system (CIAS), the plaque area and tooth area on color slides were digitized and the number of pixels automatically counted. The proposed Plaque Percent Index (P% Index) expresses plaque area as a percentage of tooth area. The reproducibility of this method was tested and the influence of photographic technique on the P% Index was determined. The association of the Turesky modified Quigley-Hein plaque index (Q-H Index) and the P% Index was assessed. The present method was highly reproducible for the P% Index with an intraexaminer variation of 0.28% and intraexaminer correlation coefficient of 0.99. The results show that highly reproducible P% Index values with an error of less than 3.0% were obtained when the photographs were taken under the following conditions. For the buccal surfaces of anterior teeth, the slides were photographed within a 20-degree range in the horizontal plane and a 30-degree range in the vertical plane; and for the lingual/palatal surfaces of anterior teeth and the buccal or lingual/palatal surfaces of posterior teeth, the slides were photographed with an image of the whole tooth surfaces in the photographic mirrors. The comparison of the Q-H Index and the P% Index revealed that for each score of the Q-H Index the corresponding values of P% Index were wide with a significant crossover value, although a strongly positive correlation was found between the Q-H Index and the P% Index (r = 0.92, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of plaque by image analysis

The uneven distribution and pattern of staining, revealed on root-planed, periodontally-involved root surfaces by the application of a plaque-disclosing solution, precludes the use of conventional plaque scoring indices or other methods of assessment based on planimetric and gravimetric techniques. A method has been developed and evaluated to quantify stained areas using image analysis. The method is reproducible, with an error factor of 1.32%, and represents a comparatively simple, yet effective technique for quantifying plaque on irregular root surface areas.

Effects of cigarette smoking on the rate of plaque formation

In 2 separate studies, plaque was harvested (i) from 15 smokers and 15 non-smokers after a 48-h period without oral hygiene, and (ii) from 15 smokers and 12 non-smokers after a 48 h hygiene-free period following complete plaque removal by toothbrushing. No significant association emerged between wet weight of accumulated plaque and cigarette smoking, in either study. In the second study, the mean plaque calcium concentration was raised in smokers compared with non-smokers, and significantly raised in 7 heavy smokers relative to non-smokers. In both instances, calcium concentration was significantly raised relative to (total) phosphorus concentration, which may indicate that the additional calcium was not in mineral deposits. These results may reflect an association between calcium concentration of plaque and tobacco consumption.

A comparison of antimicrobial activity of four disclosant dyes

Four disclosant dyes were tested for antimicrobial activity against 27 oral reference strains and five non-oral human pathogens. Erythrosine and fluorescein inhibited most gram-positive and gram-negative organisms associated with dental plaque, and were bactericidal to selected strains. Fast green and brilliant blue demonstrated little antimicrobial activity.

Comparative effects of xylitol- and sucrose-sweetened chew tablets and chewing gums on plaque quantity

The effects of chewing gums and chew tablets sweetened with sucrose or xylitol on the quantity and adhesivity of dental plaque were studied with 14 volunteer dental students (mean age 23.2). The subjects participated in a four-phase study in which one of four different test products was used during each period. The 3-d periods were interspaced with 4-d normalization phases. The following four experimental products were tested: chewing gums (CG) and chew tablets (CT), sweetened with sucrose (s) or xylitol (x). The amount of plaque was determined through an automatic planimetric procedure on teeth treated with Dentotest. The total plaque areas before brushing were significantly larger in the CTs group compared with the CTx group. After brushing, the plaque areas remained larger in the CTs group. In the determination of the thick plaque areas, the use of CTx was associated with significantly smaller plaque scores than the use of CTs. In the adhesivity studies CGx consistently yielded the lowest plaque scores, but the differences between x and s were not significant. The comparison between CT and CG suggested that CTx produced significantly smaller plaque scores than CGx before brushing, but not after. This finding was considered to result from the differences involved in the texture and chemical composition between tablets and chewing gums. The present study showed that the use of CGx and CTx was associated with clinically more advantageous plaque effects than the use of corresponding products sweetened with sucrose.

Bacteriology of human experimental gingivitis: effect of plaque and gingivitis score

The plaque flora isolated from discrete dentogingival sites during a human gingivitis experiment was analyzed as a function of the plaque score and of the gingivitis score. When the gingivitis score was plotted as a function of the plaque score, a nonbleeding gingivitis was associated with a proportional increase in the Actinomyces sp. at the expense of the Streptococcus sp. In particular, the percentage of Actinomyces israelii increased significantly, while the percent Streptococcus sanguis decreased significantly. A. israelii also increased significantly when a bleeding gingivitis developed. When the plaque score was plotted as a function of the gingivitis score, A. israelii increased significantly as the nonbleeding gingivitis developed, but A. viscosus and Bacteroides melaninogenicus increased significantly when the bleeding gingivitis developed. The availability of a sufficient number of plaques with a plaque score of 2.0 permitted the examination of the interrelationship of gingivitis and flora minus the effect of plaque biomass. The bacteriological profile showed that when bleeding occurred, the levels and proportions of A. viscosus and B. melaninogenicus increased significantly. These findings raise the possibility that proportional changes in the gingival plaque flora may uniquely contribute to the development of gingival inflammation in this experimental model.

Associations between the total fluoride content of dental plaque and individual caries experience in Australian children

Individual caries experience (DMFT) and the total fluoride content of dental plaque were determined for 72 schoolchildren, aged 9.7-13.0 years, lifelong residents in one of three New South Wales towns, where the fluoride levels of the reticulated water supplies were: Katoomba, less than 0.1 parts/10(6); Sydney, 1.0 parts/10(6) for 4 years; and Yass, 1.0 parts/10(6) for 16 years, prior to sampling. The mean fluoride content of plaque in Sydney (22.6, s.d. = +/- 16.8 parts/10(6)) and Yass (25.6, s.d. = +/- 16.4 parts/10(6)) differed significantly (t = 2.27, P less than 0.05 and t = 3.30, P less than 0.02, respectively) from that in Katoomba (13.5, s.d. = +/- 8.3 parts/10(6)). Significant inverse associations were demonstrated between total plaque fluoride and individual caries experience (DMFT) in Sydney (r = -0.45, P less than 0.025) and overall (r = -0.28, P less than 0.010). Inverse trends were established between plaque quantity (dry weight of plaque collected) and fluoride levels. No associations could be demonstrated between fluoride treatment (dentifrice, tablets or topical application) and plaque fluoride, DMFT or plaque quantity.

Effect on plaque of a xylitol-containing chewing-gum. A clinical and biochemical study

The effects on plaque induced by single or repeated use of xylitol- and sucrose-containing chewing-gums were studied on twenty subjects refraining from tooth-brushing for three days. Mechanical removal of plaque by chewing during a single period was shown to yield no significant differences between gravimetric values obtained before and after chewing. Daily use of a xylitol-containing chewing-gum reduced by 47% the weight of plaque formed in comparison to a sucrose-containing product, and by 20--41% in comparison to conditions when no chewing-gum was used. The use of a xylitol chewing-gum induced a lower invertase-like activity in plaque extra cellular phase. Results at variance with the gravimetric data were obtained by using a stained plaque scoring system; the eventual inadequacy of such plaque scoring systems was discussed.

Effect of a xylitol chewing gum on plaque quantity and quality

The aim of the present study was to further investigate the plaque-reducing effect of a xylitol-containing chewing gum. Ninety-six dental students were divided randomly into three groups: a sucrose group (n = 32), a xylitol group (n = 36) and a control group (n = 28), using a sucrose-containing chewing gum, a xylitol-containing chewing gum, or no chewing gum, respectively, during a three-day experimental plaque growth period with restricted oral hygiene. The fresh weight of plaque collected in the xylitol group was 40% lower than in the sucrose group, along with a significantly lower mean plaque index. The use of the xylitol chewing gum induced low invertase-like activity in plaque extra-cellular phase together with low carbohydrate content. These results concur to indicate advantageous effects through the use of a xylitol-containing chewing gum.