Caries arresting effect of silver diamine fluoride on dentine carious lesion with S. mutans and L. acidophilus dual-species cariogenic biofilm

Objectives: This in vitro study investigated the effects of silver diamine fluoride (SDF) on dentine carious lesion with cariogenic biofilm. Study Design: Thirty human dentine blocks were inoculated with Streptococcus mutans and Lactobacillus acidophilus dual-species biofilm to create carious lesion. They were equally divided into test and control group to receive topical application of SDF and water. After incubation anaerobically using micro-well plate at 37oC for 7 days, the biofilms were evaluated for kinetics, morphology and viability by colony forming units (CFU), scanning electron microscopy (SEM), and confocal microscopy (CLSM), respectively. The carious lesion underwent crystal characteristics analysis, evaluation of the changes in chemical structure and density of collagen fibrils using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and immune-labeling. Results: The log CFU of S. mutans and L. acidophilus in the test group was significantly lower than control group. SEM and CLSM showed confluent biofilm in control group, but not in test group. XRD showed the loss of crystallinity of dentine due to the dissolution of hydroxyapatite crystal structure in test group was less than control group. FTIR showed that log [Amide I: HPO42-] for test vs. control group was 0.31±0.10 vs. 0.57±0.13 (p<0.05). The gold-labeling density in test vs. control group was 8.54±2.44/µm2 vs. 12.91±4.24/µm2 (p=0.04). Conclusions: SDF had antimicrobial activity against the cariogenic biofilms and reduced demineralization of dentine. Key words:Caries, caries arrest, dentine, silver, silver diamine fluoride, fluoride, biofilm,cariogenic.     

Mutans streptococci strains prevalence before and after cavity preparation during Atraumatic Restorative Treatment

Critics argue that all carious dentine is not removed from the hand-prepared cavity during the Atraumatic Restorative Treatment (ART) procedure, and that the caries process is soon resumed. The aim of this study was to determine the effectiveness of ART in removing carious tissue, by investigating the numbers of mutans streptococci and lactobacilli, with emphasis on the prevalence of Streptococcus mutans and Streptococcus sobrinus strains before, and after ART treatment of dental caries. Two microbiology samples were collected. The first sample was removed from the centre of the carious lesion at the enamel-dentine junction, and the second was collected from the centre of the hard cavity wall above the pulp, after the soft infected dentine had been manually removed. A total of 71 mutans streptococci isolates from 31 children and 40 carious teeth were subcultured, biochemically characterised and genotyped by the arbitrarily primed polymerase chain reaction (AP-PCR). Results showed a significant decrease in TVC (P<0.0001), mutans streptococci (P < 0.0001) and lactobacilli (P = 0.0002) after cavity preparation. AP-PCR identified S. mutans strains that were undetectable during biotyping, and divided clinical isolates into two main clusters. In all, 63% (45/71) of isolates from the carious lesions comprised S. mutans strains. After cavity preparation, this was reduced to 35% (25/71), of which 30% (21/71) were S. mutans and the remaining 6% (4/71) S. sobrinus strains. The number of mutans streptococci strains was below detectable levels in 19 of the prepared cavities. The significant decrease in bacteria after manual cavity preparation demonstrates the reliability of a standardized ART technique, yet the presence of S. mutans strains shows that the effectiveness of the ART procedure can vary during treatment and between dental practitioners.     

The predominant microflora of nursing caries lesions.

The predominant microflora recovered from infected dentine of 52 carious teeth from 14 children with nursing caries was determined using both selective and non-selective media for the isolation of specific genera and acidified media (pH 5.2) to isolate the predominant aciduric microorganisms, and compared with the microflora of sound enamel surfaces in caries-free children. Streptococcus mutans formed a significantly greater proportion of the lesion flora while Streptococcus oralis, Streptococcus sanguis and Streptococcus gordonii formed a significantly greater proportion of the plaque flora from sound tooth surfaces. The proportions of Actinomyces naeslundii and Actinomyces odontolyticus were significantly greater in the plaque samples than in the lesion samples. Actinomyces israelii formed 18.2% of the flora from the lesions, but was not isolated from the plaque samples. The proportions of Candida albicans, Lactobacillus spp. and Veillonella spp. were also significantly greater in the carious dentine than in the plaque samples. The most frequently isolated lactobacilli were Lactobacillus casei, Lactobacillus fermentum and Lactobacillus rhamnosus. The predominant aciduric flora was S. oralis, S. mutans and A. israelii and these taxa were also isolated from a similar proportion of the lesions at pH 7.0. Strains of S. mutans, L. casei, L. fermentum and L. rhamnosus isolated from individual carious teeth were genotyped using PCR-based methods. Each species was genotypically heterogeneous and different genotypes were recovered from different carious teeth in the same child. These data indicate that the microflora of lesions in the same child is microbiologically diverse and support a non-specific aetiology for nursing caries in which the physiological characteristics of the infecting flora, not its composition, is the major determinant underlying the disease process.     

Inhibition of cultivable bacteria by chlorhexidine treatment of dentin lesions treated with the ART technique

The aim of this study was to examine the changes in the cultivable microflora of carious dentin before and after atraumatic restorative treatment (ART) and investigate the inhibitory effect of chlorhexidine-gluconate-based cavity disinfectant in the microflora. Using a split mouth design, 35 primary molar pairs with class II carious lesions in 35 patients (mean age 7.31+/-0.47 years) were selected. The total viable counts (TVC), Streptococcus mutans and lactobacilli were first measured in the center of the infected demineralized lesion and then from the hard dentine after caries removal by the ART technique. Chlorhexidine-gluconate (2%)-based cavity disinfectant was applied to one of the molar pairs and the other molar received no disinfectant treatment. Thereafter, all of the teeth were restored with glass ionomer cement (GIC). Cavities were reassessed after 6 months and again dentine samples were microbiologically investigated. Removal of carious dentine by ART significantly reduced TVC, S. mutans and lactobacilli. After 6 months, application of chlorhexidine exhibited a greater significant reduction in TVC (p=0.013), and a significant reduction in S. mutans compared to the nondisinfected group (p<0.001). A significant reduction in lactobacilli counts was observed in both groups after 6 months, but the difference between the disinfected and nondisinfected groups was not significant (p=0.056). ART was found to be effective in reducing the cultivable microflora and chlorhexidine-gluconate-based cavity disinfectant might serve as a suitable additional agent in inhibiting the residual bacteria in the dentine.     

Conventional caries removal and sealed caries in permanent teeth: a microbiological evaluation

Objectives

The aim of this study was to compare microbiological infection after conventional carious dentine removal with incomplete carious dentine removal and sealing.

Methods

Eighty-seven patients (12–50 years of age) under treatment at the Dental Clinics of the Federal University of Rio Grande do Sul (UFRGS), Brazil, participated in the study. The patients presented 90 posterior permanent teeth with primary caries. The lesions were coronal, active, and reached at least the middle third of the dentine. None of the teeth exhibited spontaneous pain, sensitivity to percussion or apical pathology (detected through radiographic exams). Pulp sensibility was confirmed by the cold test. The lesions were divided into 2 experimental groups: complete caries removal (CCR) based on hardness criteria (n = 60 lesions) and incomplete caries removal (ICR) and sealing (n = 32 lesions). Microbiological samples were obtained from the initial demineralized dentine, after CCR and after ICR-Seal.

Results

The number of anaerobic and aerobic bacteria, lactobacilli, and mutans streptococci decreased at the end of treatment (p < 0.05). Significantly less anaerobic bacteria (p < 0.01), aerobic bacteria (p = 0.02), and mutans streptococci (p < 0.01) growth was observed after ICR-Seal compared to CCR. The difference in lactobacilli was insignificant (p = 0.08). The amount of bacteria detected after conventional caries removal was higher than that which remained in sealed caries lesions.

Conclusions

The results suggest it is not necessary to remove all carious dentine before the restoration is placed because over time, sealing of carious dentine results in lower levels of infection than traditional dentine caries removal.

Clinical significance

The results of this study indicate that sealed carious dentine was less infected than the remaining dentine left after conventional caries removal and sealing. Our results support treatment of deep carious lesions in one session with incomplete removal of carious dentine.     

Clinical and microbiological performance of resin-modified glass-ionomer liners after incomplete dentine caries removal

The aims of this study were to evaluate clinically and microbiologically the effects of two resin-modified glass-ionomer cements (RMGICs) used as liners after incomplete dentine caries removal and to identify Streptococcus mutans and Streptococcus sobrinus strains isolated from dentine samples, before and after indirect pulp treatment. Twenty-seven primary molars with deep carious lesions, but without signs and symptoms of irreversible pulpitis, were submitted to indirect pulp treatment. Treatment consisted of incomplete excavation of the carious dentine, application of one of the RMGICs (Vitrebond or Fuji Lining LC) or calcium hydroxide cement (Dycal), and sealing for 3 months. Clinical evaluation (consistency, color, and wetness of dentine) and carious dentine collects were performed before temporary sealing and after the experimental period. Microbiological samples were cultivated in specific media for subsequent counting of mutans streptococci (MS) and lactobacilli (LB). MS colonies were selected for identification of S. mutans and S. sobrinus by polymerase chain reaction. After 3 months, the remaining dentine was hard and dry, and there was a significant decrease in the number of MS and LB, in all groups, although complete elimination was not achieved in 33% and 26% of the teeth for MS and LB, respectively. From 243 MS colonies selected, 216 (88.9%) were identified as S. mutans and only 2 (0.8%) as S. sobrinus. The use of resin-modified glass-ionomer liners after incomplete caries removal, as well as a calcium hydroxide cement, promoted significant reduction of the viable residual cariogenic bacteria in addition to favorable clinical changes in the remaining carious dentine.     

Inhibitory effect of silver diamine fluoride on dentine demineralisation and collagen degradation

Objective

To investigate the inhibitory effects of 38% silver diamine fluoride (SDF) on demineralised dentine.

Methods

Human dentine blocks were demineralised and allocated to four groups: SF, F, S and W. The blocks in group SF received a topical application of 38% SDF solution (253,900 ppm Ag, 44,800 ppm F), group F received a 10% sodium fluoride solution (44,800 ppm F), group S received a 42% silver nitrate solution (253,900 ppm Ag) and group W received deionised water (control). They were subjected to pH cycling using demineralisation solution (pH 5) and remineralisation solution (pH 7) for 8 days. The surface morphology, crystal characteristics, lesion depth and collagen matrix degradation of the specimens were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-CT testing and spectrophotometry with a hydroxyproline assay.

Results

The surface morphology under SEM showed evident demineralisation with exposed collagen in groups S and W, but not in group SF. Clusters of granular spherical grains were observed in the cross-sections of specimens in groups SF and F. XRD revealed precipitates of silver chloride in groups SF and S. The mean lesion depths (±SD) of groups SF, F, S and W were 182 ± 32 μm, 204 ± 26 μm, 259 ± 42 μm and 265 ± 40 μm, respectively (SDF, F < S, W; p < 0.01). Groups SF and S had significantly less hydroxyproline liberated from the dentine matrix than groups F and W (p < 0.01).

Conclusion

The use of 38% SDF inhibited demineralisation and preserved collagen from degradation in demineralised dentine.

Clinical significance

SDF application positively influences dentine remineralization.     

Partial elimination of Streptococcus mutans from selected tooth surfaces after restoration of carious lesions and SnF2 prophylaxis.

This study examined the prevalence of Streptococcus mutans in dental plaque from carious and noncarious sites before and after routine dental treatment in five young men in the US Navy. S mutans was isolated in 96.3% of the samples from carious sites and in 63.3% of the samples from noncarious sites before treatment. After all carious lesions had been restored, the prevalence of S mutans was significantly reduced, but many of the carious and noncarious sites still had detectable levels of S mutans. A further reduction in S mutans was observed after conventional 8.9% stannous fluoride paste prophylaxis and 10% stannous fluoride topical application; however, in no instance was the organism completely eliminated. About 12 to 18 months after the initial examination, new carious lesions were seen in four men who were available for reexamination. Plaque samples of new lesions had high levels of S mutans. Therefore the restorations of lesions and the stannous fluoride prophylaxis treatments given under the conditions of the study were effective but incomplete measures for eliminating S mutans from the tooth surfaces of Navy personnel and were inadequate procedures for arresting the carious process.     

老年人桩核冠修复前后龈沟内致龋菌变化的比较研究

目的 研究老年人桩核冠修复前后不同时期根面菌斑中主要致龋菌定植数量变化。方法 以单纯随机法选择下颌第一磨牙无咬合功能的患者30人,将一侧需行桩核冠修复的第一磨牙和对侧健康第一磨牙分为受试牙和对照牙。受试牙预备前、预备后 72 h、预备后 1周及冠修复后 1个月,分别采集受试牙与对照牙根面菌斑,然后进行厌氧培养、分离,通过菌落形态学检查、生化特征及聚合酶链反应（ PCR）对其中变异链球菌、内氏放线菌和黏性放线菌进行鉴定和菌落计数。结果 受试牙变异链球菌预备前、预备后 72 h、预备后 1周、修复后 1个月菌落计数的变化差异有统计学意义（ P<0.05）。受试牙黏性放线菌菌落计数在预备前、预备后 72 h、预备后 1周、修复后 1个月的变化差异有统计学意义（ P<0.05）。受试牙内氏放线菌菌落计数在预备前、预备后 72 h及1周、修复后 1月的变化差异有统计学意义（P<0.05）。结论 变异链球菌、内氏放线菌及黏性放线菌在预备后1周菌落计数增加,修复后1个月菌落计数降低。以上结果提示在牙体预备后初期,应指导患者进行菌斑控制。     

Effects of four anticaries agents on lesion depth progression in an in vitro caries model.

PURPOSE: This study compares four chemotherapeutic regimens used for inhibiting carious lesion progression: silver nitrate (AgNO3); silver fluoride/stannous fluoride (AgF/SnF2); silver diammine fluoride (SDF); and chlorhexidine (CHX). METHODS: For this study, a bacterial model system containing Mutans streptococci (MS) and Lactobacilli casei (L) was used to generate carious lesions on 85 extracted sound permanent third molars which were randomly assigned to four test groups and one control group. At week two, the four treatment regimens were applied to the lesions (one treatment per test group). RESULTS: Six weeks later, lesions treated with a single AgF/SnF2 or AgNO3 application demonstrated 29% and 19% less lesion progression, respectively, than did the control group (P < 0.05). SDF and CHX did not differ significantly from the control. CONCLUSION: AgF/SnF2 and AgNO3 may be useful in slowing down carious lesion depth progression.     

Impact of <Emphasis Type="Italic">Streptococcus mutans</Emphasis> on the generation of fluorescence from artificially induced enamel and dentin carious lesions in vitro

The purpose of this study was to examine whether Streptococcus mutans is implicated in the generation of fluorescence detected in carious lesions. Enamel surfaces and dentin cavities of extracted human teeth were subjected to artificial caries generation by exposing them either to a culture medium containing S. mutans or to a lactic acid buffer for 2 weeks. Fluorescence from the lesions was detected with confocal laser scanning microscopy or fluorescence microscopy at various excitation wavelengths, and maximum fluorescence radiance was computed using imageanalyzing software. Culture media of S. mutans were also examined for fluorescence generation. The results demonstrated that S. mutans-induced enamel and dentin lesions exhibited increased fluorescence in the red and green spectral regions, with the signal stronger in the red region. In the blue region, however, fluorescence signals in the corresponding area were below the background level. Significantly weaker or virtually no fluorescence was detected in lactic acid-demineralized lesions at all excitation wavelengths. Neither bacterial cells nor culture media generated any fluorescence. These results indicate that, although the presence of S. mutans may be a prerequisite for the emission of fluorescence from carious lesions, some interaction of S. mutans with exposed tooth matrix elements may also be required for the generation or unmasking of fluorophores.     

Pulp responses to two strains of bacteria isolated from human carious dentine (L. plantarum) (NCTC 1406) and S. mutans (NCTC 10919)

A series of studies has been conducted in which monoinfected gnotobiotic rats were used to study the responses of the dental pulp to micro-organisms isolated from carious lesions in dentine. In this study pulp responses to L. plantarum (formerly odontolyticus) (NCTC 1406) in pure culture and in combination with S. mutans (NCTC 10919) are reported. The incidence of inflammation/necrosis/dentine bridge formation observed in animals monoinfected with L. plantarum was similar to that reported in previous germ-free studies. There was a greater incidence of dentine bridge formation in rats monoinfected with L. plantarum compared with those monoinfected with S. mutans. When the two organisms were combined, periapical inflammation was observed in 14% of the teeth examined after 28 days, but there was no significant difference in the incidence of dentine bridge formation. Considerable variation in the density of staining of the two microorganisms in histological sections was observed.     

An ex vivo study of arrested primary teeth caries with silver diamine fluoride therapy

Objectives

This ex vivo study compared the physico-chemical structural differences between primary carious teeth biannually treated with silver diamine fluoride (SDF) and carious teeth without such treatment.

Method

Twelve carious primary upper-central incisors were collected from 6-year-old children. Six teeth had arrested caries after 24-month biannual SDF applications and 6 had active caries when there was no topical fluoride treatment. The mineral density, elemental contents, surface morphology, and crystal characteristics were assessed by micro-computed tomography (micro-CT), energy-dispersive X-ray spectrometry (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

Results

Micro-CT examination revealed a superficial opaque band approximately 150 μm on the arrested cavitated dentinal lesion. This band was limited in the active carious lesion. EDX examination detected a higher intensity of calcium and phosphate of 150 μm in the surface zone than in the inner zone, but this zone was restricted in the active cavitated dentinal lesion. SEM examination indicated that the collagens were protected from being exposed in the arrested cavitated dentinal lesion, but were exposed in the active cavitated dentinal lesion. TEM examination suggested that remineralised hydroxyapatites were well aligned in the arrested cavitated dentinal lesion, while those in the active cavitated dentinal lesion indicated a random apatite arrangement.

Conclusions

A highly remineralised zone rich in calcium and phosphate was found on the arrested cavitated dentinal lesion of primary teeth with an SDF application. The collagens were protected from being exposed in the arrested cavitated dentinal lesion.

Clinical significance

Clinical SDF application positively influences dentine remineralisation.     

Proportions of Streptococcus mutans, lactobacilli and Actinomyces spp in root surface plaque

Abstract – The incidence of Streptococcus mutans, lactobacilli and Actinomyces was examined in root surface dental plaque from 24 subjects with root surface caries and in 24 subjects with exposed root surfaces as a consequence of periodontitis but without root surface caries. Plaque was collected from the most posterior teeth in each quadrant: in the caries group from carious lesions and in the periodontitis group from buccal root surfaces. There were significantly higher proportions of S. mutans and lactobacilli in dental plaque samples taken from subjects suffering from root surface caries than in samples from subjects without root surface caries. The level of the group A. viscosus/naeslundii in the periodontitis group was higher than that found in the root surface caries group, but the difference was not statistically significant.     

Identification of bacteria in association with immune components in human carious dentin

Actinomyces viscosus, A. naselundii, Streptococcus mutans serotype "c" and S. mutans serotype "d/g" were identified in human carious dentin using histological and immunofluorescent techniques. A. viscosus was most frequently found in association with patient's immunoglobulins and complement, followed by S. mutans serotype "d/g", S. mutans serotype "c", and A. naeslundii.     

Identification of bacteria in association with immune components in human carious dentin

Actinomyces viscoxus, A. naselundii. Streptococcus mutans serotype "c" and S. mutans serotype "d/g" were identified in human carious dentin using histological and immunofluorescent techniques. A. viscosus was most frequently found in association with patient's immnoglobulins and complement, followed by S. mutans serotype "d/g", S. mutans serotype "c", and A. naeslundii .     

Microbial flora associated with presence of root surface caries in periodontally treated patients

Abstract — Examination of saliva and dental plaque was carried out in 35 adults who had been treated for periodontal disease 3 yr earlier. Plaque samples were collected from approximal and buccal sound and carious root surfaces. The samples were analyzed for the presence and proportions of members of Streptococcus, Lactobacillus and Actinomyces. The results showed a low prevalence of root surface caries and a low level of salivary mutans streptococci and lactobacilli. From subjects with root caries there was a not statistically significant tendency to higher proportional levels of mutans streptococci in plaque from carious root surfaces than from caries-free surfaces. An inverse significant relationship between noncarious and carious root surfaces was noted for S. sanguis. The population of A. viscosus and A. naeslundii was similar in plaque samples from sound and carious sites but showed elevated levels in the subjects with five or more new root surface lesions.     

Microbial flora associated with presence of root surface caries in periodontally treated patients

Examination of saliva and dental plaque was carried out in 35 adults who had been treated for periodontal disease 3 yr earlier. Plaque samples were collected from approximal and buccal sound and carious root surfaces. The samples were analyzed for the presence and proportions of members of Streptococcus, Lactobacillus and Actinomyces. The results showed a low prevalence of root surface caries and a low level of salivary mutans streptococci and lactobacilli. From subjects with root caries there was a not statistically significant tendency to higher proportional levels of mutans streptococci in plaque from carious root surfaces than from caries-free surfaces. An inverse significant relationship between noncarious and carious root surfaces was noted for S. sanguis. The population of A. viscosus and A. naeslundii was similar in plaque samples from sound and carious sites but showed elevated levels in the subjects with five or more new root surface lesions.     

Efficacy of diode laser application versus silver diamine fluoride (SDF) as a modification of Hall technique in primary teeth

BackgroundThe Hall technique is a new technique aimed at depriving bacteria of any substrate, thereby limiting the progression of caries. Silver diamine fluoride (SDF) and diode laser are documented to have an antibacterial effect on carious enamel and dentin by eradicating bacteria such as Streptococcus mutans.AimThe current study aimed to increase the success rate of the Hall technique in carious primary molars by eradicating bacteria present in carious lesions using SDF or diode laser in combination with the Hall technique.Materials and methodsA total of 159 children aged 4–8 years were randomly divided into three equal groups: Group I, application of the Hall technique; Group II, SDF with Hall technique; Group III, diode laser with Hall technique. Children were recalled at regular intervals over a year. Results: At the end of the follow-up period, Group III showed the highest clinical success rate (94.3 %), followed by Group II (96.2 %), while Group I showed the lowest clinical and radiographic success rates (88.7 % and 86.8 %, respectively); however, these differences were statistically non-significant.ConclusionTreatment of carious lesions using SDF or Diode Laser increased the success rate of the Hall technique in primary teeth.     

Proportions of Streptococcus mutans, lactobacilli and Actinomyces spp in root surface plaque

The incidence of Streptococcus mutans, lactobacilli and Actinomyces was examined in root surface dental plaque from 24 subjects with root surface caries and in 24 subjects with exposed root surfaces as a consequence of periodontitis but without root surface caries. Plaque was collected from the most posterior teeth in each quadrant: in the caries group from carious lesions and in the periodontitis group from buccal root surfaces. There were significantly higher proportions of S. mutans and lactobacilli in dental plaque samples taken from subjects suffering from root surface caries than in samples from subjects without root surface caries. The level of the group A. viscosus/naeslundii in the periodontitis group was higher than that found in the root surface caries group, but the difference was not statistically significant.