Occlusal fissures in equine cheek teeth: µCT and histological findings.

Fissures on the occlusal surface of equine cheek teeth are commonly encountered during oral examination. Generally, their presence is considered abnormal but their aetiopathogenesis and clinical impact on pulp disease is still undetermined. The aims of this research were to study the extent of occlusal cheek teeth fissures using high-resolution X-ray computed tomography (µCT) imaging and their histological characteristics. Twenty-seven teeth (of 15 horses) were scanned using µCT imaging to analyse fissure extent. Histological examination of a subset of teeth (n=7) was performed. Forty-three type 1 fissures (35 type 1a, eight type 1b) were identified. The mean length of the fissure of type 1a and type 1b on the occlusal surface was 3.47+/-1.60mm and 13.64+/-7.40mm, respectively. Their mean depth was 13.22+/-10.76mm and 7.42+/-6.42mm, respectively. Potential risk factors associated with fissure depth were identified using a multivariable mixed model The location of the fissure and Triadan number were significantly associated with fissure depth. Fissures could be identified on histological sections with the presence of organic material inside the fissure, microorganisms in the continuation of the fissure extending into the dentinal tubules and the presence of reactionary dentine. This study suggests that fissures can provide a pathway for microorganisms to enter the dentinal tubules, potentially resulting in local pulpal inflammation. It appears that in healthy teeth, vital odontoblasts react by producing reactionary (tertiary) dentin, which lacks patent tubules and thus provides a proper seal.

Synergy of brushing mode and antibacterial use on in vivo biofilm formation.

OBJECTIVES: Orthodontic, multi-strand retention-wires are used as a generalized model for oral retention sites to investigate whether biofilm left-behind after powered toothbrushing in-vivo enabled better penetration of antibacterials as compared with manual brushing. METHODS: 2-cm multi-strand, stainless-steel retention-wires were placed in brackets bonded bilaterally in the upper arches of 10-volunteers. Volunteers used NaF-sodium-lauryl-sulphate-containing toothpaste and antibacterial, triclosan-containing toothpaste supplemented or not with an essential-oils containing mouthrinse. Opposite sides of the dentition including the retention-wires, were brushed manually or with a powered toothbrush. Health-care-regimens were maintained for 1-week, after which wires were removed and oral biofilm was collected. RESULTS: When powered toothbrushing was applied, slightly less bacteria were collected than after manual brushing, regardless whether an antibacterial-regimen was used or not. Powered-toothbrushing combined with antibacterial-regimens yielded lower biofilm viability than manual brushing, indicating better antibacterial penetration into biofilm left-behind after powered brushing. Major shifts in biofilm composition, with a decrease in prevalence of both cariogenic species and periodontopathogens, were induced after powered brushing using an antibacterial-regimen. CONCLUSION: Oral biofilm left-behind after powered brushing in-vivo enabled better penetration of antibacterials than after manual brushing. CLINICAL SIGNIFICANCE: Mechanical removal of oral biofilm is important for prevention of dental pathologies, but biofilm is always left-behind, such as in fissures, buccal pits, interproximal areas and gingival margins and around orthodontic appliances. Use of antibacterial toothpastes or mouthrinses can contribute to removal or killing of biofilm bacteria, but biofilm structure hampers antibacterial penetration. A synergy between brushing mode and antibacterial-regimen applied exists with clinically demonstrable effects.

Molecular studies of the structural ecology of natural occlusal caries.

Microbiological studies of occlusal dental biofilms have hitherto been hampered by inaccessibility to the sampling site and demolition of the original biofilm architecture. This study shows for the first time the spatial distribution of bacterial taxa in vivo at various stages of occlusal caries, applying a molecular methodology involving preparation of embedded hard dental tissue slices for fluorescence in situ hybridization (FISH) and confocal microscopy. Eleven freshly extracted teeth were classified according to their occlusal caries status. The teeth were fixed, embedded, sectioned and decalcified before FISH was performed using oligonucleotide probes for selected abundant species/genera associated with occlusal caries including Streptococcus, Actinomyces, Veillonella, Fusobacterium, Lactobacillus and Bifidobacterium. The sites showed distinct differences in the bacterial composition between different ecological niches in occlusal caries. Biofilm observed along the entrance of fissures showed an inner layer of microorganisms organized in palisades often identified as Actinomyces, covered by a more loosely structured bacterial layer consisting of diverse genera, similar to supragingival biofilm. Biofilm within the fissure proper seemed less metabolically active, as judged by low fluorescence signal intensity and presence of material of non-bacterial origin. Bacterial invasion (often Lactobacillus and Bifidobacterium spp.) into the dentinal tubules was seen only at advanced stages of caries with manifest cavity formation. It is concluded that the molecular methodology represents a valuable supplement to previous methods for the study of microbial ecology in caries by allowing analysis of the structural composition of the undisturbed biofilm in caries lesions in vivo.

Comparative evaluation of chlorhexidine varnish and fluoride varnish on plaque Streptococcus mutans count--an in vivo study.

AIM: The aim of the study was to assess and compare the effect of chlorhexidine varnish and fluoride varnish application on Streptococcus mutans counts in plaque of occlusal pits and fissures of permanent mandibular first molars. MATERIALS AND METHODS: The study was an in vivo comparative study, conducted among 50 schoolchildren aged 7-8 years under a field setting. The 50 subjects were randomly allocated into two groups. Baseline plaque samples were collected from all the subjects followed by the application of two varnishes, Cervitec and Duraphat. The varnish was applied to pit and fissures of occlusal surface of mandibular first molar. The varnish application was carried out on the first day, fifth day and tenth day after baseline plaque sampling. Subsequent plaque samples were collected at the end of 1 month and at the end of 3 months after the varnish application. RESULTS: The Cervitec varnish has shown a statistically significant reduction at the end of 1 month and at the end of 3 months (P < 0.05). Duraphat varnish did not show a statistically significant difference in reducing the plaque S. mutans count at the end of 1 month and third month (P > 0.05). CONCLUSION: Cervitec varnish was found to be effective in reducing S. mutans count for a 3-month period, when compared to Duraphat varnish.

Effect of topical applications of a novel chlorhexidine-thymol varnish formula on mutans streptococci and caries development in occlusal fissures of permanent molars.

OBJECTIVE: To evaluate the effect of a new formula of a chlorhexidine-thymol varnish on mutans streptococci (MS) colonization and fissure caries development. METHODS: The study group consisted of 58 healthy adolescents (12-17 years old) undergoing orthodontic treatment with fixed appliances. A double-blind split-mouth design was applied, and 116 pairs of molar teeth were randomly assigned to topical varnish applications with either the new Cervitec Plus or its predecessor Cervitec. Both varnishes contained 1% CHX and 1% thymol (CHX/T) as active ingredients, but differed with respect to adhesive properties. The varnishes were applied in the fissures at baseline, and then every sixth week throughout the 48-week study period. Endpoints were MS colonization (CRT test) and occlusal laser fluorescence (LF, DIAGNOdent) recordings carried out regularly during follow-up. RESULTS: A significant reduction in the levels of MS in the fissures after the initial treatment was displayed with both varnishes (p < 0.05), and the levels remained consistently suppressed throughout the follow-up period. A non-significant but clear tendency was noted in favor of the new formula after six and 12 weeks, with fewer teeth harboring high counts (> or = 10(5) CFU) of MS (6w:12% vs. 24%, 12w:16% vs. 26%). No new lesions were registered in any subject, and the mean LF recordings did not change significantly over time in the groups. CONCLUSION: There were no statistically significant differences between the CHX/T varnishes in terms of bacterial growth and caries prevention. For MS suppression, a tendency towards an initially superior effect was displayed with the new formula.

Genotypes of Streptococcus mutans in saliva versus dental plaque.

OBJECTIVE: The aim of this study was to investigate whether genotypes of Streptococcus mutans strain can be detected as effectively in saliva samples as in plaque samples from buccal surfaces and occlusal surface fissures of permanent first molars. DESIGN: The study included 20 school children aged 6-7 years who were positive for mutans streptococci. Samples of stimulated saliva and of dental plaque on buccal surfaces and occlusal surface fissures of permanent first molars were collected. Samples were cultivated in MSB agar. Up to nine isolates compatible with mutans streptococci were obtained and identified by means of biochemical tests. All isolates identified as S. mutans were genotyped by arbitrarily primed polymerase chain reaction. RESULTS: A total of 28 genotypes of S. mutans were isolated: 23 in saliva samples, 23 in buccal surface plaque samples, and 16 in plaque samples from occlusal surface fissures. CONCLUSIONS: Although, saliva sampling did not reveal all genotypes isolated, it was equally as effective as plaque sampling from the buccal surfaces of permanent first molars, and more effective than plaque sampling from fissures on their occlusal surfaces.

Mutans streptococci colonization and longitudinal caries detection with laser fluorescence in fissures of newly erupted 1st permanent molars.

OBJECTIVE: To longitudinally apply a laser fluorescence (LF) device (DIAGNOdent) in newly erupted 1st permanent molars over a 3-year period and to relate the findings to mutans streptococci (MS) colonization, fissure morphology, and caries development. MATERIAL AND METHODS: The material consisted of 101 consecutive 5 to 6-year-old children attending a Public Dental Clinic and who volunteered after ethical approval and informed consent had been given. Only fully erupted molars with clinically sound fissures were included. At baseline, the fissures were subjectively categorized as "shallow" or "deep", and, prior to the LF readings, a plaque sample was collected and cultivated for MS using a chair-side kit. The registrations were repeated annually and the microbial samplings after 2 years. The total drop-out rate was 12%. RESULTS: The mean LF values increased significantly (p<0.05) with increasing age from 8.2 to 12.4 in the teeth that remained sound. Thirty-five teeth were decayed or filled during the follow-up and their mean LF values increased from 13.4 to 40.7. The LF readings were significantly higher in molars with "deep" fissures (p<0.05) at all visits. MS colonization at baseline was associated with an increased risk for caries (OR = 11.6, p<0.05) and significantly elevated LF readings. Baseline LF readings > or =12 were not diagnostic for dentin caries or fillings over the study period (sensitivity 0.57; specificity 0.86). CONCLUSION: LF readings could be used to some extent to monitor fissure morphology and caries development in fissures of newly permanent molars over time, but elevated initial values were not predictive for caries development.

Chlorhexidine-containing glass ionomer cement. A clinical investigation on the fissure caries inhibiting effect in first permanent molars.

UNLABELLED: Glass ionomer cement with addition of chlorhexidine used as a varnish on tooth surfaces has been shown to reduce the number of interproximal mutans streptococci (ms). The effect of a single application of such a varnish containing 2.5% chlorhexidine on occlusal caries development of the first permanent molars on 6-year-old children in a high caries incidence area was investigated. The children were examined according to WHO criteria and 262 children with 2 caries free contra-lateral molars were selected for treatment. Salivary ms samples were collected using the Strip-mutans (SM) method. After brushing the occlusal surfaces with a toothbrush and pumice in water slurry, rinsing and drying with a cotton roll, glass ionomer cement containing chlorhexidine (GI-CHX) and glass ionomer (GI) were applied randomly with a micro brush and the varnish was covered with occlusal wax. At baseline, the mean defs was 18.18 and DMFS was 0.25 and after one year 18.24 and 0.83 respectively. The salivary ms scores were high or very high (SM 2 and 3) in 85.6% at baseline. At the one-year follow up, the GI-CHX and GI materials could not be detected in the fissures. Also, a large number of fissure sealants had been placed in the molars outside the study protocol; thus 4% of the GI-CHX and GI, and 70% of the untreated were sealed at year one. Overall, there was no significant difference between the caries-reducing effect of GI-CHX and GI, but a trend towards a higher effect was seen for GI-CHX. Excluding the sealed molars the reduction was 74% in the GI-CHX-group, and 71% in the GI-group. CONCLUSION: Addition of 2.5% chlorhexidine to glass ionomer did not seem to increase the caries-reducing effect of the varnish in this high caries incidence population.

Pit and fissure sealing. Bonding of bulk-cured, low-filled, light-curing resins to bacteria-contaminated uncut enamel in high c-factor cavities.

PURPOSE: To examine the ultrastructure of bonding to occlusal enamel fissures using phosphoric acid etching in combination with a pit and fissure sealant (Clinpro Sealant), a total-etch single-bottle adhesive (One-Step) followed by the fissure sealant, and two single-step self-etch adhesives (Adper Prompt and Xeno III) followed by the fissure sealant. METHODS: Sections of bonded enamel fissures retrieved from specimens bonded in vivo were polished, and rinsed with phosphoric acid to bring surfaces into relief. They were examined, first under non-dehydrated conditions with field emission-environmental SEM, to evaluate the marginal integrity of the bonds. The same specimens were then re-examined under dehydrated conditions with conventional SEM to capture more detailed ultrastructural features. Extent of resin penetration into etched enamel was further evaluated by TEM examination of sections taken from undemineralized unstained bonded specimens. These sections were further examined after HCl demineralization and staining. RESULTS: All occlusal fissure walls examined were lined with remnant aprismatic enamel. Full penetration of resins into the bottom of the fissures, and gap-free interfaces were not observed in any of the specimens, irrespective of whether total-etch or self-etch adhesives were used with the sealant. Phosphoric acid did not penetrate well into the fissures and although hybridization of the etched aprismatic enamel was observed with or without the use of the total-etch adhesive, etching was inconsistent and gaps were frequently observed. Entrapment of bacteria within the fissure walls was frequently seen. The more aggressive self-etch adhesive Adper Prompt created etching in aprismatic enamel that approached that of phosphoric acid etching. The moderately aggressive self-etch adhesive Xeno III produced 1 mm thick hybrid layers in the aprismatic enamel fissure wall.

Consistency of DIAGNOdent instruments for clinical assessment of fissure caries.

DIAGNOdent (KaVo, Biberach, Germany) has shown high diagnostic accuracy and intra-operator agreement for caries detection, both in vitro and in vivo. The aims of this study were to compare DIAGNOdent with visual examination (VI) and bitewing radiographs (BW) for clinical assessment of occlusal fissures, and to evaluate inter-device consistency of clinical recording using four different DIAGNOdent instruments; secondly, to correlate DIAGNOdent readings with microbial culture of the measured site. The subjects were young adults, the material comprising 34 occlusal fissures, scheduled for restorative treatment at the Dental School Clinic of the University of Iceland. Two examiners conducted visual and radiographic assessments. One examiner measured each site with four DIAGNOdent instruments in random order. The fissure was then opened and lesion depth was classified on a 4-point scale. Bacterial samples were taken from the fissure before and after opening. Intra-operator agreement was high (r = 0.85-0.98). Inter-device correlation for the four DIAGNOdent instruments was significant in all cases (r = 0.81-0.92). However, a common cut-off point could not be determined. There was weak but significant correlation between DIAGNOdent readings and all three classes of lesion depth. Level of infection showed very weak correlation with the DIAGNOdent readings. It was concluded that DIAGNOdent is more reliable in detecting dentinal caries if a proper cut-off point is used than in indicating actual lesion depth. Readings from the different instruments were not directly comparable, however, owing to the lack of a common cut-off point.

Mutans streptococci and lactobacilli in saliva after the application of fissure sealants.

Because dental fissures may serve as reservoirs for mutans streptococci, preventive measures should be taken to control microbial concentrations at these sites. This study estimated the influence that sealing permanent first molars would have on the levels of mutans streptococci and lactobacilli in saliva of healthy seven-year-old schoolchildren. Permanent first molars were sealed in 31 children without caries (NC group) and in 32 children with caries (C group). None of the children had caries in their permanent first molars. Conventional methods were used to count mutans streptococci and lactobacilli in saliva before applying the sealant and again at 4 and 12 weeks after application. Baseline counts of lactobacilli and mutans streptococci were significantly higher in the C group. A significant reduction in mutans streptococci was observed in the NC group at 4 and 12 weeks. It was concluded that fissure sealants in permanent first molars can help reduce salivary levels of mutans streptococci in children without caries.

Microleakage and penetration depth of three types of materials in fissure sealant: self-etching primer vs etching: an in vitro study.

Clinical preventive procedures must be done after a risk assessment. One of the risk factors is the occlusal morphology of the posterior teeth. These caries-free fissures must be sealed. This first in vitro experimentation of the study evaluated the microleakage and the penetration depth of three types of materials by Vivadent: Helioseal F, Tetric, Tetric Flow. The teeth were etched with phosphoric acid and bonded using a one bottle bonding in order to determine the best material for the sealing of the fissure. The depth of penetration of fuschine dye as well as that of the tested material was measured with a grid. The results, compared to the depth of the fissures, are expressed in percentage of penetration. The results were as follows: penetration of fuschine dye: 0% for the 2 composites, 100% for Helioseal F; penetration of the materials: 96.90% for Helioseal F, 70.82 for Tetric and 86.10 for Tetric Flow (significant difference, Wilcoxon test = 0.0105). In this first in vitro study, Tetric Flow shows no microleakage and is more efficient when compared to Helioseal F and Tetric in obturating deep fissures of non carious bicuspids. The second experiment of the study evaluated the microleakage and the penetration depth of Tetric Flow when it is bonded by two different methods: Group 1: total etch (phosphoric acid) and Scotch-bond 1 (3M), and Group 2: self-etching primer with Prompt (Espe). There was no significant difference (p > 0.03) between classical bonding vs self-etching primer. The self-etching primer Prompt is very efficient vs phosphoric acid in obturating the fissures of non carious bicuspids with Tetric Flow. It is concluded that for prevention by sealing, using a flowable ceromer (Tetric Flow) with the self-etching (Prompt), is a really good technique.

The value of salivary bacterial counts as a supplement to past caries experience as caries predictor in children.

This study aimed to determine whether salivary mutans streptococci and lactobacilli counts could add any value to a combination of caries experience variables that was recently presented for the prediction of caries. Sixty-nine children at the age of 7.5 yr participated in this longitudinal study. Microbiological data were obtained at the ages of 7.5, 9.5 and 11.5 yr and caries data at the ages of 7.5. 9.5. 11.5, 13.5 and 15.5 yr. Spearman's correlation coefficients were computed, and forward multiple regression analyses were carried out using bacterial counts and caries experience parameters as explanatory variables and caries increment as a dependent variable. The explained variance (adjusted R2 value) was the measure used to assess the additional value of bacterial counts to the caries predictive potential of the combined parameters of the past caries experience. Correlation coefficients between bacterial counts and 4-yr caries increment were from 0.22 tip to 0.54. In all cases, the simultaneous streptococcus mutans-lactobacilli counts showed a statistically non-significant additional adjusted R2 value of <0.06. The results do not lend support to the concept that these salivary bacterial counts are useful additional caries predictors for the mixed dentition, when a combination of caries experience parameters is used.

The influence of specific foods and oral hygiene on the microflora of fissures and smooth surfaces of molar teeth: A 5-day study.

A group of 20 students, harbouring >10(4) mutans streptococci per millilitre of saliva, was enrolled into the study. Models for sampling, reproducibly, the dental plaque present in specific sites (fissure and smooth surface) on the dentition were developed and validated. Withdrawal of normal oral hygiene procedures for only 1 day resulted in approximately 10-fold increases in the number of micro-organisms recovered from both sites. The effect of supplementing the subjects' diets with particular food items given 5 times per day [lemonade (5.8% w/v sugars, 250 ml), biscuits (digestive biscuits, 67.6% w/w carbohydrate of which 22% w/w was sugars and 45.6% w/w was starch), caramel toffees and sugar lumps] on the number of micro-organisms recovered and on the composition of the flora at both sites was determined. Dental plaque samples were taken after 5 days and it was found that supplementation of the diet with toffee and sugar lumps resulted in significantly more micro-organisms at both sampling sites. The supplementation of the diets with lemonade or biscuits did not significantly alter the numbers of micro-organisms recovered from either site. The percentage composition of the plaque samples from both dental sites remained relatively unaffected by oral hygiene although there were lower levels of mutans streptococci which might be related to the use of an antimicrobial toothpaste containing fluoride, triclosan and zinc citrate. This study suggests that the cariogenicity of certain sucrose-containing foods may, in part, be due to the enhancement of plaque accumulation in addition to other effects on the percentage composition of the plaque which may become manifest on prolonged usage of these dietary foodstuffs. These observations are consistent with dietary survey findings which often find consumption of confectionery related to caries experience or incidence.

Prediction of caries development for molar fissures with semiquantitative mutans streptococci test.

Risk-specific caries prevention requires validated and simple parameters for a caries risk assessment. The aim of the study was to evaluate the validity of a site-specific chair-side mutans streptococci (MS) test for the prediction of caries incidence in fissures. In 230 6- to 7-yr-old children, occlusal plaque samples of teeth 16 and 36 were cultured with Dentocult SM tests at 37 degrees C for 24 hr. Caries (DMFS), initial caries, sealants, and a plaque index (QHI) were recorded and oral hygiene habits were assessed. Not erupted, carious, filled and sealed teeth were excluded from the analysis (n = 154). After 2 yr, the status of the fissures was re-examined, and a fluoride history was recorded with a questionnaire filled out by the children's parents. Sealed teeth were excluded again (n = 54). With a classification of MS score 0 or 1 as low and MS score 2 or 3 as high caries risk, 92% agreement was reached by two independently working examiners. The MS scores and caries incidence correlated significantly. Seventy-eight % of the caries progression in fissures was prognosed correctly. Sensitivity was 50%, specificity 82%, positive predictive value 29%, and negative predictive value 92%. Children with caries progression tended to have lower fluoride scores. Low MS scores were most likely to be associated with low caries incidence, while high mutans streptococci scores seem to be partially compensated by other parameters.

Association of salivary mutans streptococci with discoloured pits and fissures.

Experimental studies have demonstrated that mutans streptococci play a major role in caries etiology. Several previous epidemiologic studies found a positive association of salivary mutans streptococci with caries prevalence. The present epidemiologic study aimed at detecting a possible association of salivary mutans streptococci with brown discoloured pits and fissures, supposing that discolouration indicates caries. In the Canton of Zurich 1035 schoolchildren, aged 6.5-12.5, were examined with regard to caries prevalence and presence of discolourations in pits and fissures. A commercially available, semi-quantitative test was used to estimate the salivary level of mutans streptococci in each child. The salivary level (low/high) of mutans streptococci was significantly associated with the presence of slightly brown discoloured (C1), clearly brown discoloured (C2) and cavitated (C3) pits and fissures. The odds ratios were 1.5 (P<0.01) for C1, 2.5 (P<0.001) for C2 and 5.0 (P<0.001) for C3 pits and fissures. The findings are consistent with the hypothesis that brown discolouration indicates caries. Furthermore, the findings suggest that this type of discolouration at elementary school age indicates increased caries activity.

Structural analyses of plaque and caries in relation to the morphology of the groove-fossa system on erupting mandibular third molars.

Using 22 erupting human third mandibular molars, this study investigated: (1) the relationship between the morphology of the interlobal groove and the histological features of caries, (2) the ultrastructural features of the interlobal groove contents, and (3) whether the morphology of interlobal grooves influences the viability of the microorganisms. Posteruption time was classified as (1) < 3 months (7 teeth), (2) 3-12 months (8 teeth) and (3) > 12 months but < 18 months (7 teeth). The teeth were pre- and postfixed, and buccolingual sections were prepared. The mesial/distal interlobal groove on 116 sections was classified as fissure-like or groove-like. All sections were embedded and ground, and microradiographs were made. The interlobal groove contents were analyzed on two sections from each tooth, one with a fissure-like and one with a groove-like morphology, giving a total of 44 sections. Eighteen teeth (82%) had evidence of caries. Severity of caries was associated with length of posteruption time. 'Fissures' were not more prone to caries than 'grooves'. In about 70% of the 'fissures' caries had penetrated deepest at the entrance rather than in the deeper parts. LM and TEM examinations from 1 tooth disclosed erythrocytes, enamel organ cells and pioneers of microorganisms in the interlobal grooves. All other interlobal grooves were occupied by microorganisms, mainly gram-positive coccoids and small rods. Viable microorganisms were seen at the entrance as well as at the bottom part of the 'grooves'. In 'fissures' viable microorganisms were primarily observed at the entrance, while in deeper parts the microorganisms were less viable or dead. A moderate association was observed between the viability of the microorganisms and differences in the depths of caries penetration in the fissures. Thus, the internal morphology of the interlobal grooves influenced the conditions for bacterial growth and this determined the location for caries progression within the groove-fossa system.

Hidden caries: what is it? Does it exist? Does it matter?

Hidden caries is a term used to describe occlusal dentine caries that is missed on a visual examination, but is large enough and demineralised enough to be detected radiographically. The detection rate of such lesions will depend upon the prevalence of caries in the population and the frequency with which bitewing radiographic examinations are performed. Whether 'hidden caries' is a distinct clinical entity, reflecting a particular anatomical fissure topography or a different bacterial aetiology, is unknown. It is possible that an improved visual examination, with careful cleaning and drying of teeth, may improve occlusal caries detection to the point where 'hidden caries' no longer exists. However, this possibility has yet to be tested clinically and until it is, practising dentists would be wise to examine bitewing radiographs carefully for occlusal demineralisation. The authors would treat such hidden lesions by removing soft caries and placing sealant restorations.

Salivary mutans streptococci and dental caries patterns in pre-school children.

Recent studies have suggested that the identification of caries as discrete patterns may be valuable in describing and predicting caries experience on an individual basis. The purpose of this study was to assess the association between levels of salivary mutans streptococci and the prevalence, incidence and distribution of caries patterns in the primary dentition. A cohort of pre-school children (n = 146, mean age 3.8 yr) were examined for dental caries and sampled for salivary mutans streptococci (SMS) at baseline and once annually for 2 yr. Children's tooth surfaces were categorized into four patterns: pit/fissure, maxillary anterior, posterior proximal, and buccal/lingual smooth surface. Salivary mutans streptococci were enumerated using a tongue blade technique, and were categorized as low (0 CFU), moderate (1-50 CFU) and high (> 50 CFU). At year 2, children with high baseline SMS had the 1) highest prevalence of caries (87%) and the highest dmfs (9.15); 2) highest prevalence of each pattern, and 3) greatest number of patterns. Among children with the pit/fissure pattern, those with high baseline SMS had the greatest pit/fissure dmfs after 2 yr. Results show that baseline SMS levels were associated with both cross-sectional and longitudinal caries experience, numbers of caries patterns, and the prevalence and severity of those patterns.

A study into the prevention of fissure caries using an antimicrobial varnish.

The aim of this study, performed in Bangkok, was to evaluate the possibility of reducing fissure caries development using an antimicrobial varnish, Cervitec. Children aged 7-8 years and 12-13 years, 251 in each age group, with at least 2 sound contra-lateral permanent molars, were selected. A split mouth method was used with one test and one control tooth within the same jaw. At baseline and after two years all children were investigated for DMFS and DMFT. In addition, the size of any cavities was estimated. From 200 children, plaque samples of test and control occlusal surfaces were collected at baseline and after one year and processed to estimate the number of mutans streptococci. Mutans streptococci in saliva were estimated by the Strip mutans method. Cervitec varnish, containing 1 per cent chlorhexidine and thymol was applied at baseline, after 3-4 and after 8-9 months. The results showed that: Cervitec varnish reduced fissure caries development significantly; the levels of salivary mutans streptococci at baseline were significantly correlated with caries status at baseline and with total caries increment over the two-year period; caries development in a fissure was significantly correlated to the level of plaque mutans streptococci at that same site; three months after the last varnish application, a certain reduction of mutans streptococci in plaque could be seen in the test teeth; comparing the size of the lesions, more large cavities were found in the untreated teeth. It is concluded that varnishes should be considered as further options for prevention of fissure caries, possibly in more individualised programmes or in combination with already established methods.