Infiltration of Natural Caries Lesions in Relation to Their Activity Status and Acid Pretreatment in vitro

This study aimed at testing how active and inactive enamel caries lesions differ by their degree of resin infiltration, and whether the choice of acid pretreatment plays a crucial role. Four examiners assessed 104 human molars and premolars with noncavitated enamel lesions and classified them as 'active' or 'inactive' using the Nyvad criteria. Forty-five teeth were included in this study after independent unanimous lesion activity assessment. Lesions were cut perpendicularly into 2 halves. Each half lesion was pretreated with either 15% hydrochloric acid or 35% phosphoric acid. The lesions were infiltrated after staining with rhodamine isothiocyanate. Thin sections of 100 µm were prepared and the specimens were bleached with 30% hydrogen peroxide. The specimens were then counterstained with sodium fluorescein, subjected to confocal laser scanning microscopy and analyzed quantitatively. Outcome parameters were maximum and average infiltration depths as well as relative penetration depths and areas. In active lesions no significant difference of percentage maximum penetration depth and percentage average penetration depth between lesions pretreated with hydrochloric or phosphoric acid could be observed. In inactive lesions, however, phosphoric acid pretreatment resulted in significantly lower penetration compared to hydrochloric acid pretreatment. Surface conditioning with hydrochloric acid led to similar infiltration results in active and inactive lesions. Moreover, inactive lesions showed greater variability in all assessed infiltration parameters than did active lesions. In conclusion, caries lesion activity and acid pretreatment both influenced the infiltration. The use of phosphoric acid to increase permeability of the surface layer of active lesions should be further explored.

Evaluation of cavitations in proximal caries lesions at various magnification levels in vitro

OBJECTIVES: The aim of this study was to evaluate the cavitation rate of proximal caries using different magnification aids in vitro. METHODS: Radiographs of 285 extracted teeth were taken and the proximal surfaces were graded to the criteria R0 (no radiolucency), R1 (radiolucency confined to the outer half of enamel), R2 (inner half of enamel) and R3 (outer half of dentin). Subsequently, the proximal surfaces were checked for the presence of cavitations with the naked eye (NE), and by using 4.3 x magnification eyeglasses (ME), a stereo microscope (SM, 10x), or a scanning electron microscope (SEM, up to 2000 x magnification). RESULTS: In surfaces with R3 caries, cavitations were visible in 56 of 59 cases with the naked eye. When using SEM, all surfaces revealed cavitations (100%). Regarding the surfaces with R2 lesion, 36 of 46 cases showed cavitations (NE); the corresponding values were 39/46 (ME), 41/46 (SM), and 46/46 (SEM); in the latter, in most cases deep defects could be observed. With regard to R1 lesions, 36/60 (NE), 43/60 (ME), 45/60 (SM), and 58/60 (SEM) cases revealed cavitations. A breakdown of radiographically sound surfaces (R0) was present in some 10% of the examined surfaces (24/261, NE; 33/261, SEM). CONCLUSIONS: Cavitations (defined as breakdown of the surface) are present in significantly more cases than previously reported. This might be an explanation why even small radiolucencies tend to progress, albeit slowly. Thus, close follow-ups should strongly be recommended when considering a preventive treatment regimen with small radiolucencies.

Clinical performance of a new laser fluorescence device for detection of occlusal caries lesions in permanent molars

OBJECTIVES: To determine the clinical performance of a laser fluorescence device (DIAGNOdent pen, KaVo) to discriminate between different occlusal caries depths (D(0)-D(1-4); D(0-2)-D(3,4)) in permanent molars. METHODS: In this prospective, randomized two-centre-study 120 sound/uncavitated carious sites in 120 patients were measured after visual and radiographic caries assessment. In cases of operative intervention (n=86), the lesion depths after caries removal were recorded (reference). In cases of preventive intervention (n=34), the sites were reassessed visually/radiographically after 12 months to verify the status assessed before (reference). The discrimination performance was determined statistically (Mann-Whitney test, Spearman's rho coefficient, and areas under the receiver operating characteristic curves (AUCs)). Sensitivities (SE) and specificities (SP) were plotted as a function of the measured values and cut-off values for the mentioned thresholds suggested. RESULTS: Sound sites (n=13) had significantly minor fluorescence values than carious sites (n=107) (P<0.0001) as had sites with no/enamel caries (n=63) compared to dentinal caries (n=57). The AUCs for the same discriminations were 0.92 and 0.78 (P<0.001). For the D(0)-D(1-4) threshold, a cut-off at a value of 12 (SE: 0.88, SP: 0.85) and for the D(0-2)-D(3,4) threshold at 25 (SE: 0.67, SP: 0.79) can be suggested. A moderate positive correlation between the measurements and the caries depths was calculated (rho=+0.57, P=0.01). CONCLUSION: Within this study, the device's discrimination performance for different caries depths was moderate to very good and it may be recommended as adjunct tool in the diagnosis of occlusal caries.

Influence of dental materials used for sealing caries lesions on laser fluorescence measurements

The aim of this study was to determine the influence of thickness and aging on the intrinsic fluorescence of sealing materials and their ability to block fluorescence from the underlying surface as assessed using a laser fluorescence device. Cavities of 0.5 mm and 1 mm depth were drilled into acrylic boards which were placed over two surfaces with different fluorescence properties: a low-fluorescence surface, to assess the intrinsic fluorescence of the sealing materials, and a high-fluorescence surface, to assess the fluorescence-blocking ability of the sealing materials. Ten cavities of each depth were filled with different sealing materials: Adper Scotchbond Multi-Purpose, Adper Single Bond 2, FluroShield, Conseal f and UltraSeal XT Plus. Fluorescence was measured with a DIAGNOdent pen at five different time points: empty cavity, after polymerization, and 1 day, 1 week and 1 month after filling. The individual values after polymerization, as well as the area under the curve for the different periods were submitted to ANOVA and the Tukey test (p < 0.05). At 0.5 mm, Scotchbond, FluroShield and UltraSeal showed insignificant changes in intrinsic fluorescence with aging and lower fluorescence after polymerization than Single Bond and Conseal. At 1 mm, Scotchbond and FluroShield showed the lowest intrinsic fluorescence, but only Scotchbond showed no chagnes in fluorescence with aging. At both depths, Scotchbond blocked significantly less fluorescence. All sealing materials blocked more fluorescence when applied to a depth of 1 mm. At 0.5 mm, fissure sealants blocked more fluorescence than adhesives, and did not show significant changes with aging. Scotchbond had the least affect on the fluorescence from the underlying surface and would probably have the least affect on the monitoring of sealed dental caries by laser fluorescence.

Different bacterial models for in vitro induction of non-cavitated enamel caries-like lesions: microhardness and polarized light miscroscopy analyses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Isolated development of inner (wall) caries like lesions in a bacterial-based in vitro model

The study conducted in a bacterial-based in vitro caries model aimed to determine whether typical inner secondary caries lesions can be detected at cavity walls of restorations with selected gap widths when the development of outer lesions is inhibited. Sixty bovine tooth specimens were randomly assigned to the following groups: test group 50 (TG50; gap, 50 microm), test group 100 (TG100; gap, 100 microm), test group 250 (TG250; gap, 250 microm) and a control group (CG; gap, 250 microm). The outer tooth surface of the test group specimens was covered with an acid-resistant varnish to inhibit the development of an outer caries lesion. After incubation in the caries model, the area of demineralization at the cavity wall was determined by confocal laser scanning microscopy. All test group specimens demonstrated only wall lesions. The CG specimens developed outer and wall lesions. The TG250 specimens showed significantly less wall lesion area compared to the CG (p < 0.05). In the test groups, a statistically significant increase (p < 0.05) in lesion area could be detected in enamel between TG50 and TG250 and in dentine between TG50 and TG100. In conclusion, the inner wall lesions of secondary caries can develop without the presence of outer lesions and therefore can be regarded as an entity on their own. The extent of independently developed wall lesions increased with gap width in the present setting.

Different bacterial models for in vitro induction of non-cavitated enamel caries-like lesions: Microhardness and polarized light miscroscopy analyses

The aim of this study was to compare different bacterial models for in vitro induction of non-cavitated enamel caries-like lesions by microhardness and polarized light microscopy analyses. One hundred blocks of bovine enamel were randomly divided into four groups (n = 25) according to the bacterial model for caries induction: (A) Streptococcus mutans, (B) S. mutans and Lactobacillus acidophilus, (C) S. mutans and L. casei, and (D) S. mutans, L. acidophilus, and L. casei. Within each group, the blocks were randomly divided into five subgroups according to the duration of the period of caries induction (4-20 days). The enamel blocks were immersed in cariogenic solution containing the microorganisms, which was changed every 48 h. Groups C and D presented lower surface hardness values (SMH) and higher area of hardness loss (ΔS) after the cariogenic challenge than groups A and B (P < 0.05). As regards lesion depth, under polarized light microscopy, group A presented significantly lower values, and groups C and D the highest values. Group B showed a higher value than group A (P < 0.05). Groups A and B exhibited subsurface caries lesions after all treatment durations, while groups C and D presented erosion-type lesions with surface softening. The model using S. mutans, whether or not it was associated with L. acidophilus, was less aggressive and may be used for the induction of non-cavitated enamel caries-like lesions. The optimal period for inducing caries-like lesions was 8 days.

PAR-2 Regulates Dental Pulp Inflammation Associated with Caries

Protease-activated receptors (PARs) are G-protein-coupled receptors that are activated enzymatically by proteolysis of an N-terminal domain. The cleavage and activation of PARs by serine proteases represent a novel mechanism by which such enzymes could influence the host inflammatory response. The aim of this study was to determine whether PAR-2 expression and activation were increased in dental caries. Using immunohistochemistry, we showed PAR-2 to be localized to pulp cells subjacent to caries lesions, but minimally expressed by healthy pulp tissue. Trypsin and the PAR-2 agonist (PAR2-AP) activated PAR-2 in an in vitro functional assay. Endogenous molecules present in pulp cell lysates from carious teeth specifically activated PAR-2, but those from healthy teeth failed to do so. The activation of PAR-2 in vitro was shown to increase the expression of the pro-inflammatory mediator cyclo-oxygenase-2 (COX-2), providing a mechanism whereby PAR-2 could modulate pulpal inflammation.

Caries incidence following tooth replacement for partially dentate elders

Objective: To compare caries incidence following two different tooth replacement strategies for partially dentate older patients; namely functionally orientated treatment according to the principles of the Shortened Dental Arch (SDA) and conventional treatment using Removable Partial Dentures (RPDs). Method:A randomised controlled clinical trial (RCT) was conducted of partially dentate patients aged 65 years and older. Patients were randomly allocated to two different treatment groups: the RPD group and the SDA group. Each member of the RPD group was restored to complete arches with cobalt-chromium RPDs used to replace missing teeth. Patients in the SDA group were restored to a shortened arch of 10 occluding pairs of natural and replacement teeth using adhesive bridgework. All of the operative treatment was completed by a single operator. Caries incidence was measured over a 2-year period following treatment intervention and recorded using the International Caries and Detection System (ICDAS). Result:In total, 89 patients completed the RCT (45 SDAs and 44 RPDs). Patients in the RPD group recorded a significantly higher incidence of new carious lesions (p<0.001) and recurrent carious lesions (p<0.001) compared to the SDA group. A mixed model of covariance (ANCOVA) revealed that treatment group (p<0.001) and co-morbidity (p<0.001) were significant predictors of caries incidence. Conclusion:Two years after provision of prosthodontic treatment there was a significantly higher incidence of new and recurrent caries lesions in subjects provided with RPDs compared with SDA treatment. This will have a significant impact on the ongoing maintenance costs for these two treatment groups.

Dental caries prevalence in children up to 36 months of age attending daycare centers in municipalities with different water fluoride content

This study determined the prevalence of cavitated caries lesions (CCL) and early childhood caries (ECC), and the contribution of some variables in children up to 36 months of age attending daycare centers in municipalities with different fluoride levels in the water supply: AFC (adequate fluoride content) and LFC (low fluoride content). After approval of the Ethics Committee, the parents were interviewed. The children were clinically examined using the same codes and criteria established by the WHO (World Health Organization) and the ADA (American Dental Association). Fisher's exact test (p<0.05) was applied for statistical analysis of data. The dmft indices calculated in the LFC and AFC municipalities were 0.57 and 0.68, respectively. Considering all children examined, 17.6% presented CCL and 33.8% ECC. The economic classification, mother's education level and duration of breastfeeding were considered statistically significant with regards to CCL prevalence. The age group, duration of the habit of drinking milk before bedtime and age at which oral hygiene started were considered statistically significant with regards to ECC prevalence.

Socio-behavioral factors influence prevalence and severity of dental caries in children with primary dentition

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

In vivo evaluation of laser fluorescence performance using different cut-off limits for occlusal caries detection

The aim of this in vivo study was to evaluate the performance of laser fluorescence (LF) comparing different cut-off limits for occlusal caries detection. One hundred and thirty first permanent molars were selected. Visual examination and LF assessments were performed independently. The extent of caries was assessed after operative intervention. New cut-off limits were established and compared with those proposed by the manufacturer and by Lussi et al. (Eur J Oral Sci 109:14-19, 2001). Similar sensitivity and higher specificity was found at D(2) (considering as disease only dentin caries) when the LF cut-off limits proposed by Lussi et al. and the new one were compared. At the D(3) threshold (considering as disease only deep dentin caries), no statistically significant difference among the cut-off limits for sensitivity was found. However, the new cut-off limits showed higher specificity. The LF device provided good ability to detect dentin caries lesions. Furthermore, the new cut-off limits and the values proposed by Lussi et al. could be suggested for the in vivo detection of occlusal caries.

Reproducibility and accuracy of the ICDAS-II for occlusal caries detection

Objectives:The aim of this in vitro study was to assess the inter- and intra-examiner reproducibility and the accuracy of the International Caries Detection and Assessment System-II (ICDAS-II) in detecting occlusal caries.Methods:One hundred and sixty-three molars were independently assessed twice by two experienced dentists using the 0- to 6-graded ICDAS-II. The teeth were histologically prepared and classified using two different histological systems [Ekstrand et al. (1997) Caries Research vol. 31, pp. 224-231; Lussi et al. (1999) Caries Research vol. 33, pp. 261-266] and assessed for caries extension. Sensitivity, specificity, accuracy and area under the ROC curve (A(z)) were obtained at D(2) and D(3) thresholds. Unweighted kappa coefficient was used to assess inter- and intra-examiner reproducibility.Results:For the Ekstrand et al. histological classification the sensitivity was 0.99 and 1.00, specificity 1.00 and 0.69 and accuracy 0.99 and 0.76 at D(2) and D(3), respectively. For the Lussi et al. histological classification the sensitivity was 0.91 and 0.75, specificity 0.47 and 0.62 and accuracy 0.86 and 0.68 at D(2) and D(3), respectively. The A(z) varied from 0.54 to 0.73. The inter- and intra-examiner kappa values were 0.51 and 0.58, respectively.Conclusions:ICDAS-II presented good reproducibility and accuracy in detecting occlusal caries, especially caries lesions in the outer half of the enamel.

Artificial methods of dentine caries induction: A hardness and morphological comparative study

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Validity and reproducibility of a laser fluorescence system for detecting the activity of white-spot lesions on free smooth surfaces in vivo

The aim of the study was to determine the reproducibility and validity of DIAGNOdent in detecting active and arrested caries lesions on free smooth surfaces. Volunteers were selected from state schools of Piracicaba, São Paulo, Brazil. Overall, 220 lesions were clinically examined. Two specially trained ('calibrated') examiners performed both clinical and laser evaluations independently, and after a 1-week interval, the examinations were repeated, the intra-examiner agreement for the laser evaluation was substantial (kappa(ex1) = 0.79, kappa(ex2) = 0.71). There was almost perfect agreement between the two examiners for the clinical examination (kappa(ex1) = 0.95, kappa(ex2) = 0.85). The inter-examiner agreement showed substantial reproducibility (kappa = 0.77) for the laser examination and almost perfect agreement (kappa = 0.85) for the clinical evaluation. The validation criterion was the clinical examination of white spots, recorded as active or arrested. The sensitivity was 0.72 and the specificity was 0.73, which indicates that the DIAGNOdent was a good auxiliary method for detecting incipient caries lesions on free smooth surfaces. The utilization of both methods can improve the efficacy of caries diagnosis. Copyright (C) 2002 S. Karger AG, Basel.