Parameters associated with active caries lesions assessed by two different visual scoring systems on occlusal surfaces of primary molars – a multilevel approach

Braga MM, Martignon S, Ekstrand KR, Ricketts DNJ, Imparato JCP, Mendes FM. Parameters associated with active caries lesions assessed by two different visual scoring systems on occlusal surfaces of primary molars – a multilevel approach. Community Dent Oral Epidemiol 2010; 38: 549–558. © 2010 John Wiley & Sons A/S Abstract – Objective: The aim of this in vivo study was to evaluate the association between several parameters related to children and to their teeth, and the presence of active carious lesions assessed by two different visual indices on occlusal surfaces of primary molars. Methods: Occlusal surfaces of 757 primary molars in 139 children (3–12 years old) were classified as sound, or having inactive or active carious lesions using the Nyvad criteria (NY) and the International Caries Detection and Assessment System (ICDAS‐II) and a supplemental lesion activity assessment system (ICDAS‐LAA). Several parameters related to the tooth and to the child were recorded. Associations between these parameters and the presence of active carious lesions on occlusal surfaces were evaluated using logistic multilevel analysis. Results: Second primary molar teeth and children with high caries experience were more frequently with active occlusal carious lesions compared to sound and inactive occlusal carious lesions classified by both visual scoring systems. Teeth with a mature dental plaque on the occlusal surface and younger children had more active caries than inactive occlusal carious lesions (excluding sound teeth in the analysis). A previous visit to a dentist was related to a lower frequency of active occlusal carious lesions classified by NY only, and upper primary molars presented with higher numbers of active occlusal carious lesions classified by ICDAS‐LAA. Conclusions: Presence of mature dental plaque and tooth type are tooth‐related variables associated with active carious lesions on occlusal surfaces of primary teeth, as well as anterior caries experience and age are variables related to the child.     

Dental caries among children from Solntsevsky – a district in Moscow, 1993

Abstract In order to provide a baseline for planning a caries preventive program for children in a district in Moscow, samples of 6-, 8-, 10-, 12-, and 14-yr-old children were examined. The initial examination included recording of plaque on selected surfaces using a classification from 0 to 2 (thick plaque). After supervised tooth brushing, the children were examined for caries. Each tooth surface was examined and classified in progressive stages of caries involving opaque enamel lesions, increasing stages of cavity formation, fillings with and without caries and extractions due to caries. Gingival status in selected locations was classified from 0 to 2 (severe inflammation). More than 2/3 of the children had surfaces covered with thick plaque (score 2). Gingivitis was observed in one or more places in 2/3 of the children. Caries experience in the primary dentition was high, and low to moderate in the permanent dentition. However, the average number of surfaces with deep dentin cavitation, indicating pulpal involvement in 14-yr-olds, was 1.7. Caries on primary molar teeth accounted for about 80% of the accumulated caries experience among the 8-yr-olds. Caries on permanent first molars accounted for about 70% of the accumulated caries experience among the 14-yr-olds. The occlusal surface on permanent first molars was the most prone to caries in the permanent dentition.     

Long-term follow-up of inactive occlusal caries lesions: 4-5-year results

Objective

To assess the clinical behavior of inactive caries lesion on the occlusal sites of permanent molars over 4–5 years and to estimate the risk for progression of caries-inactive sites compared with sound ones.

Methods

Clinical examinations were conducted at baseline (n = 258) and after 4–5 years and included the recording of dental plaque and dental caries at the occlusal surfaces and the eruption stage of each permanent molar.

Results

One hudred ninety-three schoolchildren were followed (response rate of 74.8%), totalizing 1152 teeth. Of the children, 30.6% (n = 59) presented at least one molar containing an active lesion, filling, or that had been extracted; according to the activity criterion, inactive lesions presented around a twofold increased risk for caries progression than sound surfaces (OR = 2.34 95%CI = 1.51–3.62). Thirteen percent (n = 25) of the children presented at least one molar progressing to dentine cavity, filling, or extraction; according to the severity criterion, inactive caries lesions presented a significantly higher risk for progression when compared with sound surfaces (OR = 2.69, 95% CI = 1.50–4.83).

Conclusion

The vast majority of lesions (85–90%) identified as inactive enamel caries at baseline did not progress over 4–5 years. Despite this fact, it was possible to detect an increased risk for caries progression in caries-inactive occlusal sites compared with the sound ones.

Clinical relevance

Considering the low progression rates, inactive caries lesions do not need a specific caries-controlling treatment and should be monitored longitudinally in the same manner as sound surfaces.

     

Effect of sugarcane chewing on plaque pH in rural Kenyan children.

In 5 rural Kenyan children, the effect of sugarcane chewing on plaque pH was compared with the effect of a mouthrinse with 10% sucrose at various intraoral sites. They all had poor oral hygiene and at least two carious cavities in occlusal surfaces of molars. pH measurements were conducted under field conditions using paladium touch microelectrodes connected to a battery-operated pH meter. There was a marked difference in pH response of non-carious approximal sites between maxilla and mandible, with the lowest values in the maxilla. However, the pH recovery following the instantaneous drop occurred in parallel even if most pH values had not returned to baseline values 30 min after the sucrose rinse. Following the sugarcane chewing, the pH fall was less pronounced on all sites, and within 5-10 min the values had returned to resting pH and even exceeded this. In carious cavities, a similar pattern was observed, although the acidity in these sites was more pronounced, also reflected in a lower resting mean pH. The main conclusion from this study is that sugarcane chewing yields a less pronounced pH drop and a quicker pH recovery in dental plaque than is seen following a mouthrinse with 10% sucrose. This difference probably results from stimulation of salivary flow associated with the chewing.     

Prevalence and distribution of dental caries in a late medieval population in Finland.

The aim was to document the late medieval material and to compare the results with findings in other medieval populations and present-day Finns. The sample consisted of the remains of 410 individuals and included 4581 permanent and 600 deciduous teeth. Age determination was based on the stage of dental development and on the attrition pattern in the molar region. Scoring the presence and location of caries was done visually with the aid of a dental probe. In the younger age groups, caries was most prevalent in the occlusal fissures, but the proportion of cavities at these sites declined with age, possibly because occlusal attrition progressed more rapidly than did caries. In the permanent dentition, carious lesions were most frequently observed at the cementum-enamel junction, particularly on the approximal surfaces. The prevalence of caries was lower than among modern populations of similar ages. In addition, the relative distribution of caries was strikingly different, with root caries being the most common type.     

Use of palladium touch microelectrodes under field conditions for in vivo assessment of dental plaque pH in children.

The aim of this study was to assess the applicability of palladium touch microelectrodes, connected to battery-run pH meters, for in vivo plaque pH measurements in children. The pH was assessed in 20 7-year-old and in 19 14-year-old caries-active and caries-inactive rural Kenyan children. The resting pH was measured at non-carious interproximal and occlusal sites and in open dentine cavities. Independent repeated measurements were performed at given sites at intervals of 15 s and 5 min and on different days. The resting plaque pH varied widely among the children, and there was no significant difference between caries-active and caries-inactive groups. The most striking feature was the considerable erratic fluctuations of pH at a given site with time, both in resting and in sucrose-challenged plaque. These fluctuations were sensitively recorded by palladium touch microelectrodes. After a sucrose rinse, not all sites in the same mouth behaved in a similar fashion, and thus the classical 'Stephan curve' was not always apparent. In conclusion, the palladium touch microelectrodes are highly applicable for plaque pH measurements in children, even under extreme field conditions.     

Multivariate survival analysis for the identification of factors associated with cavity formation in permanent first molars

This investigation used a multivariate survival model, which allowed for dependent caries data with possible censoring, to analyse the impact of timing of tooth emergence, gender and several reported oral hygiene and dietary habits on the incidence of cavity formation in permanent first molars (PFM) in young children. A 6-yr prospective oral health screening project in Flanders, Belgium, provided clinical and questionnaire data on 4,468 children. The results revealed that PFM in children who reported frequent brushing, who had no visible caries experience in the primary dentition, and who presented without occlusal plaque on the PFM had the best survival estimates. Girls had a higher incidence than boys of cavity formation in mandibular molars. The multiple survival analysis confirmed the major impact of the caries status of the deciduous dentition and self-reported oral hygiene habits on the incidence of cavities in permanent first molars.     

Occlusal caries detection in permanent molars according to WHO basic methods, ICDAS II and laser fluorescence measurements

This epidemiological study aimed to compare the diagnostic outcome of the WHO criteria, ICDAS II criteria, laser fluorescence measurements, presence of plaque and roughness as activity scores on occlusal fissures and buccal/palatal pits of the first permanent molars. The study involved 311 children between 8 and 12 years of age from the Ennepe-Ruhr District in North Rhine-Westphalia, Germany. The surface-related caries status was registered according to the WHO basic method criteria (1997). Additionally, pit and fissure sealants, the ICDAS II visual criteria, the DIAGNOdent reading, plaque retention and surface roughness were documented. Caries experience was 1.0 (+/-2.5) DMFS. About 70% of the examined students had no obvious dentin caries in the permanent dentition (DMFS = 0). Sealants were registered on 1.4 (+/-1.7) occlusal fissures and 0.4 (+/-0.9) palatal/buccal pits. Noncavitated caries lesions were recorded as ICDAS II score 1-4 on 1.8 (+/-1.6) fissures and 1.5 (+/-1.4) pits. The comparison of the diagnostic methods suggests a relationship between higher ICDAS II scores/DIAGNOdent values and a proportional increase in the occurrence of plaque as well as in the number of rough surfaces. In conclusion, this study showed the diagnostic potential of the ICDAS II criteria in comparison to the traditional WHO criteria by means of the noncavitated caries lesions additionally detected. The DIAGNOdent use in field studies that already apply detailed visual criteria seems to bring limited additional information. While the presence of plaque provides information for the caries activity assessment more work is required to provide information about the contribution of surface roughness.     

Prevalence of noncavitated and cavitated carious lesions in 5-year-old head start schoolchildren in Alachua County, Florida

PURPOSE: The diagnosis of early carious lesions is essential for nonsurgical management of dental caries. This report describes the prevalence of early noncavitated and cavitated carious lesions in the primary dentition of 5-year-old Head Start schoolchildren in Alachua, Fla. METHODS: As part of the Fluoride Varnish Study conducted at the University of Florida, modified caries diagnostic criteria-which differentiated caries lesion activity and severity-were developed for the primary teeth. Dental examinations were conducted on 221 children ages 5 years by 2 calibrated examiners. RESULTS: Overall, 86% of the children had experienced noncavitated or cavitated caries lesions in the primary dentition. Prevalence of cavitated dentinal lesions was 48%, and prevalence of active noncavitated enamel lesions was 71%. The mean number of active noncavitated enamel lesions (mean +/- SEM: 2.91 +/- 0.21) was slightly higher than the mean number of cavitated dentinal lesions (2.52 +/- 0.31). The mean number of restored surfaces was 1.24 (+/- 0.42), and only 8% of the children had 1 or more restored surfaces. Noncavitated lesions were most common on occlusal surfaces, especially in mandibular second molars. African-American children had a higher prevalence of noncavitated lesions (81%) than whites (69%) or others (33%; P<.0001). Prevalence of cavitated lesions was 49% for African Americans, 46% for whites, and 48% for others. CONCLUSIONS: This study shows that noncavitated enamel and cavitated dentinal lesions are common in this study population's primary dentition. There is a need for preventive measures and treatment of decay in these children living in low-income families.     

Results after 1 year of non-operative occlusal caries treatment of erupting permanent first molars

The aim of this study was to evaluate a treatment program designed to control occlusal caries on the basis of intensive patient education and professional toothcleaning. The sample consisted of 56 6-8-yr-old children with their permanent right first molars in different stages of eruption. Data from the program were compared with previous data recorded in a similar sample of children. After 1 yr the majority of children in the study group had their permanent right first molars in full occlusion. A significant decrease of surfaces with easily detectable plaque and an increase of surfaces without plaque was observed. The proportion of arrested lesions increased and active enamel lesions decreased. Fissure sealing was only needed in two teeth in contrast to more than 2/3 of molars in a comparable sample of children. The program proved to be an efficient alternative to fissure sealing in preventing occlusal caries in erupting teeth.     

Microbiological assessment of occlusal brown-spot lesions in primary molars

Conventional cultural methods were used to compare the plaque flora and the level of infection of the dentine underlying 51 occlusal brown-spot lesions and 21 sound occlusal sites on the primary dentition. Freshly extracted primary molar teeth were used, and occlusal brown-spot lesions and sound occlusal sites were identified using laser fluorescence (LF) and clinical visual methods. A standardized plaque sample was taken from each site, and an LF score was recorded for one discrete site per tooth. The teeth were carefully opened at each predetermined site to determine the clinical status of the underlying dentine, and samples were collected using a sterile bur. The microbiota of the plaque and dentine samples were enumerated and identified. The mean LF scores for the sound sites and brown-spot lesions were 1.2 and 30.5 (p < 0.001), and all the sound sites exhibited hard sound dentine, but 6 out of 51 brown spots exhibited softened dentine. Overall there was no significant (p > 0.1) difference between the level of infection of the dentine of the sound and brown-spot sites, although some sites in the brown-spot lesions yielded high numbers of bacteria. However, the numbers of bacteria as log10(CFU per sample + 1) +/- SE recovered from the plaque above the brown-spot lesions were significantly greater than above the sound sites, i.e. 2.89 +/- 0.24 and 0.89 +/- 0.33, respectively. These data indicate that brown-spot lesions may be more plaque retentive than sound sites and that they are either arrested or arresting lesions, which may require preventive intervention.     

Relationship among mutans streptococci, "low-pH" bacteria, and lodophilic polysaccharide-producing bacteria in dental plaque and early enamel caries in humans

Multiple interactions occur among major determinants of dental caries. We have studied the bacterial flora and pH-lowering capacity of the same dental plaques in relation to caries. The findings on the plaque flora are reported here. The buccal surfaces of upper teeth in each subject were selected for study. A low-caries group had no "white spot" caries (ws) in the selected dentition area; a higher-caries group averaged 4.1 ws in this area. The latter group was divided into subjects with 2, 3, or 4 ws and subjects with 5, 6, or 7 ws. Enumerated organisms in plaque samples (sound and ws sites) from all subjects were: (1) mutans streptococci (MS) on mitis-salivarius-bacitracin and mitis-salivarius agar; (2) non-mutans streptococci (non-MS) on mitis-salivarius agar; (3) organisms that were categorized according to their minimum pH in sugar broth, i.e., the predominant undifferentiated total flora on blood agar or the predominant non-MS flora on mitis-salivarius agar; and (4) iodophilic polysaccharide-storing organisms on trypticase-yeast extract-salts agar. Plaques covering ws lesions contained generally only low proportions (< 0.1%) of MS. The plaque proportions of all the above 4 bacterial groups were increased in the higher-caries group but were similar for s and ws sites in this group. Over half of the total plaque flora in subjects with 5, 6, or 7 ws consisted of "low-pH"-type organisms (minimum pH < 4.4). Many of these were neither MS nor "low-pH" non-MS. The numerical emergence of MS in plaque appeared to be preceded often by other types of "low-pH" bacteria, including the non-MS. Caries development in the absence or presence of MS as well as different bacterial successions in plaque can be explained readily by the dynamic and positive relationship among the factors carbohydrate consumption, plaque flora composition, plaque acidogenic potential, and caries activity.     

Mutans streptococci and lactobacilli in breast-fed children with rampant caries.

This study aimed to investigate the prevalence of selected components of the oral microflora in breast-fed children who developed rampant caries (resembling nursing caries) under hitherto unexplained circumstances. Dental plaque and saliva samples were collected from breast-fed children, aged between 1 and 2.5 years, with and without rampant caries. Mutans streptococci and lactobacilli were isolated from dental plaque of all children with rampant caries and from most caries-free children. None of the colonies of mutans streptococci resembled those of Streptococcus sobrinus. The mean counts of the mutans streptococci and lactobacilli were 100-fold higher in plaque samples from children with rampant caries as compared with caries-free children. No difference could be found between the numbers of mutans streptococci in plaque overlaying cavities and that from adjacent sound enamel. In contrast, the counts of lactobacilli in plaque were approximately 100-fold higher from cavities than from sound surfaces. The levels of mutans streptococci in saliva were directly related to the presence of rampant caries. The results show that caries-free and caries-active breast-fed children, aged 1 to 2.5 years, harbour mutans streptococci and lactobacilli on their teeth. Rampant caries in these children can occur in the absence of nursing bottles or any other feeding abuse during weaning and in the presence of an aciduric plaque microflora, as has been reported for children with nursing bottle caries.     

Association between clinical parameters and the presence of active caries lesions in first permanent molars

The aim of the present study was to evaluate the association between clinical parameters and the presence of active caries lesions on the occlusal surface of first permanent molars. Forty eight children (5.8-13.8 years-old) with at least one first permanent molar present were selected. The clinical parameters evaluated were gender, age, DMF-T and dmf-t, presence of active white spots in other teeth, general plaque index, tooth's dental arch (upper or lower), tooth's side (right or left), presence of visible plaque and eruption degree of the first permanent molars. The first permanent molars were evaluated through visual inspection by two examiners in order to assess the presence of active or inactive caries lesions on the occlusal surface. Univariate and multivariate analyses for determination of the association between clinical parameters and the presence of active caries lesions in these teeth were performed. The presence of active white spots in other teeth was associated with the presence of active caries lesions in the first permanent molars, in both univariate and multivariate analyses (Odds ratio = 8.8 and 1.9, respectively). The presence of abundant visible plaque on the occlusal surface of the first permanent molars (Odds ratio = 3.5 in the univariate analysis, and 3.9 in the multivariate one) also presented a significant association. In conclusion, the presence of active white spots in other teeth and the presence of considerable visible plaque were associated with the presence of active caries lesions on the occlusal surfaces of first permanent molars.     

Dental plaque and caries on occlusal surfaces of first permanent molars in relation to stage of eruption

The occlusal surfaces of partly and fully erupted first right permanent molars were examined with respect to the occurrence and distribution of plaque and dental caries in a group of 57 six- to eight-year-old children. The children were classified into four groups ranging from one tooth partially erupted to full occlusion. Occlusal plaque was recorded at two levels of examination: (1) visible plaque and (2) detailed mapping by means of a plaque detector system. Dental caries was recorded after professional cleaning. The recording of plaque was repeated after 48 hr without oral hygiene. The findings showed a significant reduction in the easily detectable plaque in fully erupted teeth, compared with the three groups representing partly erupted teeth. The detailed mapping of plaque showed a clear pattern of preferential locations related to the macromorphology of the occlusal surfaces, and revealed reduction in the frequency of thick plaque accumulation in the fully erupted teeth. The proportion of active lesions was reduced in fully erupted teeth, and arrested lesions were mainly observed in the same group. This indicated that erupting teeth are more likely to develop dental caries, due to favorable conditions for plaque accumulation. Functional usage of teeth in addition to improved access for toothbrushing promoted arrestment of lesions initiated during eruption.     

The pH of dental plaque in its relation to early enamel caries and dental plaque flora in humans

Dental caries appears to result from the action of multiple, interrelated factors. A companion study dealt with the plaque-flora/caries relationship (van Ruyven et al., 2000). The plaque-pH/caries relationship is the subject of this study. Since both studies involve the same subjects, plaques, and tooth surfaces, data on the examined factors have also been integrated. In vivo plaque pH determinations (microelectrode) were done on buccal sound (s) and "white-spot" (ws) caries surfaces in a selected dentition area in a low-caries (no ws) and higher-caries subject group. The pH response to sugar was evaluated before and after a sugar rinse, a local sugar application, or sucking on a sugary lozenge. pH profiles with sugar rinsing and normal or limited salivary flow conditions, showed progressively decreasing plaque pH values at various time points in the order of: low-caries subjects (s sites), higher-caries subjects (s sites), higher-caries subjects (s + ws sites), and higher-caries subjects (ws sites). The minimum pH values showed the same trend. Analyses of all data indicated only a statistical difference for minimum values for s sites in low-caries subjects vs. ws sites in higher-caries subjects, and for s and ws sites in the latter. Local sugar application and sucking on a sugary lozenge induced smaller pH drops than sugar rinsing; such suboptimal sugar exposure caused a disappearance of the difference between the minimum pH values for s and ws sites observed with sugar rinsing in the higher-caries subjects. Initial plaque pH values were similar regardless of subject or tooth caries status. The values were also not correlated with the plaque levels of strongly iodophilic polysaccharide-storing bacteria. Collectively, both studies indicate that increasing subject caries status is characterized by increasing plaque levels of highly-acid-tolerant, acidogenic bacteria and an increasing plaque-pH-lowering potential and support the dynamic relationship between these parameters.     

Caries levels and patterns in head start children in fluoridated and non-fluoridated, urban and non-urban sites in Ohio, USA

The purpose of the study was to determine caries levels and prevalences of previously identified caries patterns in low income children in the primary dentition in Ohio, USA. Children were examined from urban fluoridated (n = 505), urban non-fluoridated (n = 395), non-urban optimal fluoride (n = 183), and non-urban suboptimal fluoride (n = 227) sites. Caries scores were similar for the two sites having optimal fluoride; scores from fluoridated sites were lower than scores from the two suboptimal fluoride sites. Children from all four sites were caries-free ranging from 36% in the urban non-fluoridated site to 50% in the non-urban optimally fluoride site. More children in the suboptimal fluoridated sites had smooth surface lesions than in the optimally fluoridated sites. More children with defect associated lesions had fewer than six (chi 2 = 222; P less than 0.01) carious surfaces than did children with smooth surface lesions.     

Dental plaque and caries on permanent first molar occlusal surfaces in relation to sagittal occlusion

This study examines the influence of sagittal occlusion on occlusal plaque formation in permanent first molars (PFM) in 72 7–10-yr-olds before loss of primary second molars. Of a total of 288 PFM, 140 (49%) were sealed and 23 (8%) filled. Occlusal plaque was recorded at two levels of examination: 1) visible plaque on the entire surface and 2) detailed macromorphologic mapping. Enamel caries was recorded after professional tooth cleaning. After 48 h without tooth brushing, plaque examinations were repeated. Stone models were used for 1) identification of interocclusal contact areas and 2) classification of sagittal molar occlusion. The detailed mapping of plaque on unfilled surfaces showed a clear pattern of preferential locations related to the macromorphology of the occlusal surfaces. Active caries was restricted to those anatomic structures where plaque accumulated. 48-h median plaque values on mandibular molars in normal and with one cusp distal occlusion were significantly lower ( P < 0.01) compared to surfaces in 1/4, 1/2 and 3/4 distal molar occlusion. Maxillary molars with normal and with 1 cusp distal occlusion had lower median plaque values than other sagittal occlusion categories. In general, however, plaque scores were higher in maxillary teeth because more than 2/3 of these teeth were without occlusal contact in the distal part. Mandibular occlusal surfaces in normal and with one cusp distal occlusion had significantly fewer active lesions than teeth with 1/4, 1/2 and 3/4 cusp distal occlusion. The significant influence of variations in sagittal molar relation on occlusal plaque formation and caries initiation occurring in fully erupted PFM before loss of primary second molars thus supports the view that physical forces operating during mastication are an important factor for colonization and growth of bacteria with cariogenic potential.     

Risk factors for dental caries in children with cerebral palsy

This study was conducted to examine the oral condition and the salivary and microbiological parameters associated with dental caries in 62 children with cerebral palsy, who came from households of low socioeconomic status (Study Group). This group had mixed (6 to 11 years old) and permanent (11 to 16 years old) dentition. Dental examinations were performed to measure dental caries, plaque index, salivary levels of mutans streptococci and lactobacilli, salivary flow rate, pH of stimulated saliva, and buffer capacity of saliva. A group of 67 non-handicapped children from similar socioeconomic backgrounds also were examined using these parameters (Control Group). Data were analyzed statistically by non-parametric tests and by correlation. The results showed that children with cerebral palsy who had permanent dentitions had a higher mean decayed, missing and filled surfaces index, as well as a higher plaque index for both sexes. Microbiological examination revealed higher levels of mutans streptococci among Study Group subjects with mixed dentition than in the Control Group. Also, lactobacillus counts were higher in the Study Group, regardless of sex or dentition. With respect to salivary flow rate, pH and buffering capacity, lower mean values were obtained for the Study Group.     

Association of the microbial flora of dental plaque and saliva with human root-surface caries

Dental plaque was obtained from one or two sound root surfaces of subjects with different degrees of root-surface caries experience. From subjects with root-surface caries, plaque samples were also obtained from either one incipient or one more advanced lesion. Proportions of the total flora were determined for total streptococci and different streptococcal species, total and different Actinomyces species, and lactobacilli. A sample of saliva was obtained from about one-third of the subjects for determination of the concentrations of mutans streptococci and lactobacilli. The main observations were: (1) Subjects without root-surface caries or restorations (group I), as compared with subjects with root-surface caries with or without restorations (group II), were characterized by having a lower prevalence and proportion of mutans streptococci and a higher prevalence and proportion of A. naeslundii in plaque on sound root surfaces; (2) subjects in group I also tended to have a lower salivary concentration of mutans streptococci and lactobacilli than subjects in group II; (3) dental plaque on sound surfaces in group II subjects contained a lower proportion of mutans streptococci than plaque associated with incipient or advanced lesions; and (4) the prevalence and proportion of lactobacilli in plaque associated with sound as well as carious root surfaces were very low. The data reinforce findings from other studies and indicate that, as for coronal caries, the plaque and saliva populations of mutans streptococci specifically are correlated positively with the presence of root-surface caries.