Elimination of E. faecalis with NaOCl versus chlorhexidine gluconate from primary molar root canal systems: an ex vivo model study.

OBJECTIVES: This ex vivo human study aimed to evaluate the efficacy of NaOCl and chlorhexidine gluconate (CHG) irrigations in eliminating Enterococcus faecalis from the RCS of primary molars. MATERIALS AND METHODS: Disinfected extracted primary molars were inoculated with E. faecalis for 24 h. Then, the RCS samples were then irrigated with either 2.5% NaOCl, 0.2% and 2% CHG, or sham saline. The samples were collected immediately after irrigation; and 24 h later, the bacterial viability and counts were measured using blood agar and qRT-PCR, respectively. Histological sections were used to measure E. faecalis penetration and viability in dentin tubules using fluorescence microscopy. RESULTS: The recovery of viable E. faecalis after the irrigation of the primary molars showed more significant bactericidal effects of NaOCl and 0.2% and 2% CHG than of saline. Immediately after the irrigation, the NaOCl group showed the greatest reduction in E. faecalis; and 24 h later, all the groups had lower viable E. faecalis than the saline control. The bacterial penetration was also lowest in the NaOCl group, although there was no difference in bacterial viability in the tubules between the groups. CONCLUSION: In primary teeth, NaOCl and CHG showed similar degrees of bacterial elimination efficacy in terms of E.faecalis. CLINICAL RELEVANCE: Within the limitations of this study, NaOCl and CHG have the similar ability to perform endodontic irrigation of primary ex vivo teeth regarding the elimination of E.faecalis, but NaOCl penetrates dentin tubules better.

The effect of root canal preparation tapers on planktonic bacteria and biofilm reduction in the apical third: A correlative microtomography and microbiological laboratory study.

AIM: To evaluate the influence of different preparation tapers on the reduction in planktonic bacteria and biofilms of Enterococcus faecalis and Candida albicans in the apical third (4 mm) of the mesial roots of mandibular molars, correlating decontamination with canal shape. METHODOLOGY: After microtomography analysis for morphological standardization of the canals, 48 mandibular molar roots, each containing two canals (96 canals), were contaminated with E. faecalis and C. albicans and divided into four groups (n = 11) for canal instrumentation using ProDesign Logic 2 files with different tapers G (.03): # 25.03; G (.04): # 25.04; G (.05): # 25.05; and G (.06): # 25.06 and irrigation with 2.5% sodium hypochlorite. Four roots were examined under a scanning electron microscope (SEM) to qualitatively assess biofilm formation. Eight roots were used as the negative control group (samples were not contaminated). Bacteriological samples were taken exclusively from the apical third of the roots before and after chemical-mechanical preparation and bacterial counts were determined (CFU/mL). The final micro-CT scan was used to quantify the volume variation and unprepared canal area in the apical third. Statistical analysis was performed using the Kruskal-Wallis, Student-Newman-Keuls and Wilcoxon tests for analysis of microbiological data. anova and the Tukey or Games-Howell test were used for analysis of micro-CT data and Spearman's test for correlations (α = 5%). RESULTS: All groups showed a significant reduction in bacteria (p < .05), with no statistically significant difference between groups. There was no significant difference in per cent volume increase between groups. The unprepared area (Δ%) was affected by the file used (p = .026) and was significantly lower for G (.06) compared to G (.03). There was no statistically significant correlation among bacterial reduction, volume and unprepared area (p > .05). CONCLUSION: The different preparation tapers influenced root canal shaping in the apical third but did not improve decontamination in this region.

Assessment of the endodontic microbiota of abscessed primary teeth using microarray technology.

CONTEXT: Knowledge of the microbial composition of abscessed primary tooth is limited. AIM: The aim was to investigate the presence of 10 oral bacterial species in samples from abscessed primary tooth root canals using microarray technology and to determine their association with clinical findings. SUBJECTS AND METHODS: The samples were collected from root canals of 20 primary molars with acute primer infection. The bacterial composition of the samples was semi-quantitatively defined using a microarray system (ParoCheck®). Clinical parameters included the presence of spontaneous pain, mobility, percussion sensitivity and swelling. STATISTICAL ANALYSIS: Data were statistically analyzed by Student' t-test, Fisher's exact Chi-square test, Freeman-Halton-Fisher's exact test, and Spearman's rho correlation analysis. RESULTS: All the tested species were detected in the samples. Fusobacterium nucleatum was the most frequent bacterium (100%), followed by Parvimonas micra (65%), Provetella intermedia (45%), and Treponema denticola (45%). According to paired bacterial combinations, F. nucleatum was significantly positively correlated with P. intermedia and P. micra (P < 0.05). T. denticola was significantly positively correlated with Porphyromonas gingivalis, Tannerella forsythia, Campylobacter rectus, and P. micra, while it was negatively correlated with Eikenella corrodens (P < 0.05). No statistically significant relationships were found between the presence of any bacteria and clinical findings. CONCLUSION: Microarray technology used in this study has demonstrated the presence of various bacteria with varying proportions in the root canals of abscessed primary teeth. The results regarding the high rate of certain bacterial combinations suggest the enhanced pathogenicity due to additive or synergistic effects of these microbial combinations.

Microbial Load After Selective and Complete Caries Removal in Permanent Molars: a Randomized Clinical Trial.

The aim of this randomized clinical trial was to compare the remaining microbial load after treatments based on complete and selective caries removal and sealing. Patients with active carious lesions in a permanent molar were randomly allocated into 2 groups: a test group (selective caries removal-SCR; n=18) and a control group (complete caries removal - CCR; n=18). Dentin samples were collected following the excavation and three months after sealing. Streptococcus species, Streptococcus mutans, Lactobacillus species, and total viable microorganisms were cultured to count the viable cells and frequency of species isolation. CCR resulted in significant lower total viable microorganisms counts (p≤0.001), Streptococcus species (p≤0.001) and Lactobacillus species (p≤0.001) initially. However, after sealing, a decrease in total viable microorganisms, Streptococcus species, and Lactobacillus species in the SCR resulted in no difference between the groups after 3 months. In conclusion, selective caries removal is as effective as complete caries removal in reducing dentin bacterial load 3 months after sealing.

Antimicrobial Photodynamic Therapy as an Adjunct for Clinical Partial Removal of Deciduous Carious Tissue: A Minimally Invasive Approach.

This study aimed to evaluate the use of antimicrobial photodynamic therapy (aPDT) as an adjunct for minimally invasive treatment (partial removal of carious tissue-PRCT) of deciduous carious tissue evaluating its efficacy in reducing microorganisms. For that, a clinical study was design including children with deciduous molars with active deep caries lesions (DCL). PRCT was performed and remaining dentin was treated with 100 µg mL-1 methylene blue solution (5 min) and than irradiated with a low power laser emitting red light (InGaAIP-indium gallium aluminum phosphide; λ = 660 nm; 100 mW; 300 J cm-2 ; 90 s; 9 J). The colony forming units (CFU) count after PRCT and after PRCT + aPDT/mg of dentin were compared for total microorganisms, including Candida spp., the mutans streptococci group, Streptococcus spp. and Lactobacillus spp. The dentin was classified (color, consistency and humidity). The microbial reduction varied from 69.88% to 86.29% and was significantly observed for total microorganisms, mutans streptococci, Streptococcus spp. and Lactobacillus spp (P < 0.001). The dentin type did not influence reduction of microorganisms (P > 0.05). The aPDT presents a promising future for clinical use as an adjunct for the reduction of microorganisms in PRCT of DCL in all kinds of dentin.

Ex vivo assessment of synergic effect of chlorhexidine for enhancing antimicrobial photodynamic therapy efficiency on expression patterns of biofilm-associated genes of Enterococcus faecalis.

BACKGROUND: It has clearly been demonstrated that Enterococcus faecalis, as a persistent microorganism, is the major agent in the etiopatogeny of endodontic infections. Recently, the limitations of conventional endodontic therapy have given rise to many attempts to introduce antimicrobial photodynamic therapy (aPDT) as an alternative treatment. The aim of this study was to analyze the ex vivo effect of aPDT in combination with 2.0% chlorhexidine (CHX) as a conventional therapy on colony count and expression patterns of genes associated with biofilm formation of E. faecalis. MATERIALS AND METHODS: A total of 125 extracted human single-rooted teeth were divide into six groups (A-F; n = 20) and were incubated with E. faecalis. Group A- photosensitizer (indocyanine green [ICG]); B- diode laser; C- aPDT; D- 2.0% CHX; E- aPDT with photosensitizer modified by 2.0% CHX; and F- control group (no procedure was performed). Five remaining teeth were used to confirm the presence of E. faecalis biofilm via scanning electron microscope. Counts of colony forming units (CFUs) in each group were evaluated separately and quantitative real-time PCR (qRT-PCR) was then applied to monitor genes expression of fsrC, efa, and gelE involved in E. faecalis biofilm. RESULTS: The results showed that none of the tested groups achieved eradication or inhibition of biofilm. On the other hand, aPDT + 2.0% CHX, 2.0% CHX, and ICG- mediated aPDT groups showed significantly less CFU/mL than ICG and diode laser groups. The group with the lowest CFU/mL count was the aPDT + 2.0% CHX, being statistically different from all other groups that could decrease the expression levels of efa, gelE, and fsrC genes 6.8-, 8.3-, and 12.1-fold, respectively. CONCLUSION: Based on the results, the synergism effect of ICG-aPDT with 2.0% CHX leads to modulation of the virulence of E. faecalis strains biofilm model by suppressing the expression of the genes associated with biofilm formation.

Microbial load after selective and complete caries removal in permanent molars: a randomized clinical trial

Abstract The aim of this randomized clinical trial was to compare the remaining microbial load after treatments based on complete and selective caries removal and sealing. Patients with active carious lesions in a permanent molar were randomly allocated into 2 groups: a test group (selective caries removal-SCR; n=18) and a control group (complete caries removal - CCR; n=18). Dentin samples were collected following the excavation and three months after sealing. Streptococcus species, Streptococcus mutans, Lactobacillus species, and total viable microorganisms were cultured to count the viable cells and frequency of species isolation. CCR resulted in significant lower total viable microorganisms counts (p≤0.001), Streptococcus species (p≤0.001) and Lactobacillus species (p≤0.001) initially. However, after sealing, a decrease in total viable microorganisms, Streptococcus species, and Lactobacillus species in the SCR resulted in no difference between the groups after 3 months. In conclusion, selective caries removal is as effective as complete caries removal in reducing dentin bacterial load 3 months after sealing.

Resumo O objetivo deste ensaio clínico randomizado foi comparar os microrganismos remanescentes após tratamentos baseados em remoção total de tecido cariado e selamento e a remoção seletiva de tecido cariado e selamento. Pacientes com lesões de cárie ativas em molares permanentes foram divididos aleatoriamente em dois grupos: grupo teste (remoção seletiva de tecido cariado-SCR; n=18), e grupo de controle (remoção total de tecido cariado-CCR; n=18). Amostras de dentina foram obtidas após a remoção da tecido cariado e após 3 meses de selamento das cavidades. Streptococcus spp., Streptococcus mutans, Lactobacillus spp. e microrganismos viáveis totais foram cultivados para contagem de células e frequência de isolamento de espécies. CCR resultou em menores contagens totais de microorganismos viáveis (p≤0,001), Streptococcus spp. (p≤0,001) e Lactobacillus spp. (p≤0,001) inicialmente. Entretanto, após o selamento, uma redução significativa nas contagens totais de microrganismos viáveis, Streptococcus spp. e Lactobacillus spp. resultou em nenhuma diferença entre os grupos após 3 meses. Conclui-se que a remoção seletiva de cárie é tão seletiva quanto a remoção completa de cárie na redução da infecção dentinária após três meses com selamento da lesão.

Biological response to self-etch adhesive after partial caries removal in rats.

OBJECTIVES: The purposes of this study were to evaluate a model of slow caries progression and to investigate the performance of a self-etch adhesive system for partial caries removal. MATERIALS AND METHODS: Rat molars were infected with Streptococcus sobrinus 6715 culture. Different time points were analyzed: days 78, 85, and 95 (± 2). After this, the samples were processed for morphological analysis. Additionally, the first molars were restored with zinc oxide and eugenol (IRM™; Dentsply; Brazil) or adhesive system (Clearfil SE Bond™; Kuraray Medical; Japan) 78 days after caries induction. After, 3 or 15 days post-treatment, the animals were euthanized, and their mandibles were processed for morphological analysis, classified by means of scores, and submitted to statistical analysis. Subsequently, immunohistochemical analysis was performed for osteonectin (OSN) and transforming growth factor-ß1 (TGF-ß1) expression. RESULTS: According to the caries induction model used, on day 95 greater inflammatory infiltration (p < 0.001), and more extensive degradation of secondary/primary dentin were demonstrated than on day 78 (p < 0.05). Furthermore, the restorative materials presented similar performance (p > 0.05) and proved to be fundamental to control the carious lesion. The TGF-ß1 and OSN were shown to be active during the caries process. CONCLUSIONS: The slow caries lesion model was feasible for morphological analysis of the dentin-pulp complex. The self-etch adhesive system triggered no acute inflammatory infiltration or pulp necrosis, instead it seemed to stimulate early pulp repair. CLINICAL RELEVANCE: Clearfil SE Bond™ applied directly on caries-affected dentin did not predispose to pulp inflammation; instead, it appeared to provide early biological benefits.

Microbiological Evaluation of Ozone on Dentinal Lesions in Young Permanent Molars using the Stepwise Excavation.

AIM: To assess the microbial effect of ozone gas on dentinal lesions in young permanent molars using the stepwise excavation. STUDY DESIGN: An experimental, controlled clinical trial was performed. The sample included 80 immature first permanent molars, showing deep occlusal carious cavities that were indicated for stepwise excavation. Following first step of dentin excavation, the sample was divided into test (ozone gas) and control (calcium hydroxide (Ca(OH)2) base material) groups. One half of the cases in each group were evaluated for microbiological changes after 6 months, and the other half after 12 months. RESULTS: Mutans streptococci (MS), Lactobacilli, and Candida counts were significantly reduced immediately after ozone application in the test group (P ≤0.05). At the final assessment period, MS and Lactobacilli were significantly reduced in the test group (P ≤0.05). Meanwhile, the Candida counts were significantly reduced only in the test group of the 6 and 12 month-cases (P ≤0.05). Regarding the control group, the significant reduction in microbial count was observed with MS after 6 and 12 months (P ≤0.05). No significant differences were observed between test and control groups at different evaluation periods (P >0.05). CONCLUSIONS: Ozone gas had a significant antimicrobial effect in deep class I carious lesions.

The in vitro effect of Antimicrobial Photodynamic Therapy on dental microcosm biofilms from partially erupted permanent molars: A pilot study.

BACKGROUND: Antimicrobial Photodynamic Therapy (aPDT) could enhance the prevention of dental caries lesions in pits and fissures of partially erupted molars, by killing microorganisms from complex dental biofilms. This pilot study aimed to evaluate the effect of Antimicrobial Photodynamic Therapy (aPDT) on the viability of specific microorganism groups of dental microcosm biofilms from occlusal surfaces of first permanent molars in eruption. METHODS: Dental microcosm biofilms grown on bovine enamel blocks, from dental plaque collected on occlusal surfaces of a partially erupted lower right first permanent molar, with McBain medium plus 1% sucrose in anaerobic condition at 37 °C for 72 h. The experiments were performed in eight groups: L-P- = no treatment (control), L18.75P- = 18.75 J/cm2 LED, L37.5P- = 37.5 J/cm2 LED, L75P- = 75 J/cm2 LED, L-P+ = 200 mM TBO, L18.75P+ = 200 mM TBO + 18.75 J/cm2 LED, L37.5P+ = 200 mM TBO + 37.5 J/cm2 LED, and L75P+ = 200 mM TBO + 75 J/cm2 LED. The counts of total microorganisms, total streptococci and mutans streptococci were determined on selective media agar plates by colony-forming units per mL. The log-transformed counts were analyzed by Kruskal-Wallis and post-hoc Dunn's test (P < 0.05). RESULTS: The counts of all microorganisms treated in the group L75P+ were statistically lower than those treated in L-P-. The aPDT promoted a significant reduction of microorganisms, with a trend of dose-dependent effect. CONCLUSION: TBO-mediated aPDT was effective in reducing the viability of specific microbial groups in dental microcosm biofilms originated from occlusal of permanent molars in eruption.

Antibacterial effect and physical properties of chitosan and chlorhexidine-cetrimide-modified glass ionomer cements.

AIMS: To compare antibacterial effect and physical properties of chitosan (CH) modified glass ionomer cement (GIC) (10% v/v), chlorhexidine-cetrimide (CHX-CT) modified GIC (2.5/2.5% w/w) and conventional GIC. MATERIALS AND METHODS: A total of fifty healthy children of age 7-12 years were selected and randomly assigned to class A and B for in vivo analysis. Slabs of CH modified GIC (Group II) along with slabs of conventional GIC (Group I, control) were cemented on buccal surfaces of maxillary molars (split-mouth technique) for class A children. Similarly, slabs of CHX-CT modified GIC (Group III) were cemented against control (Group I, control) in class B children. Slabs were assessed after 48 h for microbial load of Streptococcus mutans and Lactobacillus (LB) on mitis salivarius-bacitracin and Man Rogosa Sharpe agar media, respectively. Agar diffusion test was done to access the antibacterial effect of each group against Streptococcus muatns and LB. Slabs and cylinders of GICs were made for in vitro evaluation of compressive and flexure strength in each group. RESULTS: Comparison was done by nonparametric Kruskal-Wallis analysis followed by Dunn's multiple comparison test. Categorical groups were compared by Chi-square test. The increase in antibacterial activity (Group II > III > I) (P < 0.001) and marked increase in compressive and flexure strength (Group II > I > III) were observed. CONCLUSIONS: In the view of findings, it is concluded that CH modified GIC would be effective in inhibiting the bacteria associated with dental caries along with improved physical properties when compared with CHX-CT modified GIC and conventional GIC.

[Effect of molar ligation and local Porphyromonas gingivalis inoculation on alveolar bone loss in the mouse].

OBJECTIVE: To compare the extent and time course of alveolar bone loss and osteoclast activation in two murine models of periodontal disease: molar ligation and Porphyromonas gingivalis (P. gingivalis) oral inoculation. METHODS: A split-mouth design was applied to two groups of mice (C57BL6, 6-8 weeks old, n=24 in both groups), resulting in four treatment groups: (1) Control group: unligated upper right 2nd molars receiving CMC only, (2)Ligature group: ligation of a 9-0 suture around the upper left 2nd molar, (3) P. gingivalis group: unligated upper right 2nd molar receiving P. gingivalis challenge only, (4)Ligature+P.gingivalis group: ligation of the upper left 2nd molar in combination with oral inoculation with 109 colony-forming units(CFU) P. gingivalis. Alveolar bone loss was measured as the cementoenamel junction and alveolar bone crest (CEJ-ABC) distance. In the study, 48 C57BL6 mice were designed and treated as described above, and osteoclasts were counted on histological sections following tartrate-resistant acid phosphatase (TRAP) staining and counts were normalized to alveolar bone surface distance. Then 36 C57BL6 mice were investigated, of which 30 were ligated a 9-0 silk ligature around the 2nd molar in the left maxillary quadrant and 6 were not ligated. After ligation for 1 week, the ligatures in 12 mice were taken off for either 1 week or 2 weeks. The CEJ-ABC distance of the 6 mice without ligation was baseline. The CEJ-ABC distances were measured and analyzed. The data were analyzed with one-way ANOVA. RESULTS: Molar ligation induced marked alveolar bone loss after 3, 6, 9 and 12 weeks [(0.16±0.04) mm, (0.16±0.02) mm, (0.18±0.03) mm, (0.17±0.02) mm], vs. corresponding controls [(0.09±0.03)mm,(0.10±0.01)mm,(0.12±0.04)mm,(0.12±0.01)mm] and P. gingivalis group [(0.09±0.03)mm, (0.12±0.01)mm,(0.12±0.02)mm,(0.10±0.01)mm], P<0.05. Combined treatment with molar ligation and P. gingivalis did not further increase the CEJ-ABC distance. Evidence for osteoclast activation was found one day after molar ligation, and TRAP-positive cell numbers peaked on day 3 (12±4 vs. control 2±2, P<0.01). After taking off ligature following ligation for 2 weeks, it showed significantly regrowth of alveolar bone compared with that before removal of the ligature on day 7 [(0.07±0.02)mm vs. (0.13±0.01)mm, P<0.01]. CONCLUSION: Molar ligation is a rapid and effective way to induce periodontal bone loss in mice. Osteoclast activation occurs within 24 hours of ligature placement, and the extent of bone loss well exceeds that of the P.gingivalis-induced bone loss. Removing ligature after periodontal disease might help bone regeneration by regrowth of the alveolar bone.

Photodynamic Inactivation of Cariogenic Pathogens Using Curcumin as Photosensitizer.

OBJECTIVE: This investigation assessed the susceptibility of Streptococcus mutans and Lactobacillus acidophilus to Photodynamic Therapy (PDT) when grown simultaneously in dentine carious lesions. BACKGROUND DATA: PDT is a technique that utilizes light to activate photosensitizers in the presence of oxygen to produce reactive radicals. MATERIALS AND METHODS: A culture medium of 1% glucose, 2% sucrose, 1% young primary culture of L. acidophilus 108 CFU/mL, and S. mutans 108 CFU/mL was utilized to inoculate the bacterial induced caries on human dentine slabs. Different concentrations of the photosensitizer (0.75, 1.5, 3.0, 4.0, and 5.0 g/L) were activated through exposure to the light-emitting diode source with a central wavelength of 450 nm and a fluency of 5.7 J/cm2. Two light intensities (19 and 47.5 mW/cm2) were tested. Four different groups were analyzed: L-D- (control group), L-D+ (drug group), L+D+1 (PDT group 1, light intensity of 19 mW/cm2), and L+D+2 (PDT group 2, light intensity of 47.5 mW/cm2). ANOVA/Tukey tests were utilized to compare groups (α = 5%). RESULTS: Both light intensities required 5.0 g/L of curcumin for significant bacterial reduction (p < 0.05). No significant effect was found for L-D+, thus proving the absence of a potential inherent toxicity. CONCLUSIONS: Curcumin has a toxic effect on microorganisms at appreciable concentrations upon photoactivation. However, it was required to use the maximum concentration of the drug for a successful procedure.

Adjunctive Steps for Disinfection of the Mandibular Molar Root Canal System: A Correlative Bacteriologic, Micro-Computed Tomography, and Cryopulverization Approach.

INTRODUCTION: This study evaluated the disinfecting ability of chemomechanical preparation with rotary nickel-titanium instruments, followed by 2 distinct adjunctive procedures in the root canals of extracted mandibular molars by means of a correlative analytical approach. METHODS: Twenty-two extracted mandibular molars were selected and anatomically matched between groups on the basis of micro-computed tomographic analysis. In the first phase of the experiment, root canals were contaminated with Enterococcus faecalis and subjected to chemomechanical preparation with BT RaCe instruments and 2.5% NaOCl irrigation. Then either XP-Endo Finisher instrument or passive ultrasonic irrigation was used to supplement disinfection. Micro-computed tomography was used to show whether the percentage of unprepared areas correlated to bacterial counts. In the second phase, the same teeth were contaminated once again, and the adjunctive procedures were used. Samples from the isthmus area of mesial roots and the apical 5-mm fragment of distal roots were obtained by cryopulverization. Samples taken before and after treatment steps in both phases were evaluated by quantitative polymerase chain reaction and statistically analyzed. RESULTS: In phase 1, preparation in both groups resulted in substantial decrease of bacterial counts (P < .001). The adjunctive approaches led to a further small bacterial reduction, which was significant for XP-Endo Finisher (P < .05). No significant differences were observed between groups for persisting bacterial counts. Correlative analysis revealed no statistically significant relationship between bacterial reduction and the percentage of unprepared areas (P > .05). In phase 2, both methods had significant antibacterial effects in the main canal, but none of them could predictably disinfect the isthmus/recess areas. CONCLUSIONS: Both XP-Endo Finisher and passive ultrasonic irrigation exhibited antibacterial effectiveness, but only the former caused a significant reduction in the bacterial counts after chemomechanical preparation. None of them were effective in predictably disinfecting the isthmus/recess areas.

The effect of a chlorhexidine-fluoride varnish on mutans streptococci counts and laser fluorescence readings in occlusal fissures of permanent teeth: A split-mouth study.

OBJECTIVE: To evaluate the effect of a new chlorhexidine-fluoride varnish on mutans streptococci (MS) counts and laser fluorescence (LF) readings in fissures of permanent molars. METHOD AND MATERIALS: The study group consisted of 57 healthy schoolchildren (7 to 14 yrs) that volunteered after informed consent. A double-blind split-mouth design was employed and 87 pairs of non-cavitated permanent molars were randomly assigned to treatments with either chlorhexidine-fluoride varnish (CHX-F) or chlorhexidine-thymol varnish (CHX-T, Cervitec Plus) as active control. The varnishes were topically applied at baseline and every sixth week throughout the 24-week study period. Endpoints were MS counts (CRT test) and occlusal LF readings (DIAGNOdent pen) registered regularly during follow-up. RESULTS: At baseline, > 50% of the occlusal fissures harbored high MS counts (≥ 105 CFU), but a significant decrease (P < .05) was found after treatment with both varnishes. After 24 weeks, less than 5% exhibited high counts. There were no significant differences between the varnishes at any time point. The mean LF values were similar in both treatment groups at baseline, but a significant reduction (P < .05) was scored in the CHX-F group after 12 and 24 weeks. A similar reduction was found also in the CHX-T group after 24 weeks. No adverse events were reported. CONCLUSION: There were no significant differences between the CHX-F and CHX-T varnishes in terms of MS suppression after four applications over 24 weeks. Both varnishes also reduced the LF readings significantly compared with baseline, but further long-term studies are needed to confirm a caries-preventive effect.

Efficacy of 4 Irrigation Protocols in Killing Bacteria Colonized in Dentinal Tubules Examined by a Novel Confocal Laser Scanning Microscope Analysis.

INTRODUCTION: The aim of this study was to determine the efficiency of 4 irrigation systems in eliminating bacteria in root canals, particularly in dentinal tubules. METHODS: Roots of human teeth were prepared to 25/04, autoclaved, and inoculated with Enterococcus faecalis for 3 weeks. Canals were then disinfected by (1) standard needle irrigation, (2) sonically agitating with EndoActivator, (3) XP Endo finisher, or (4) erbium:yttrium aluminum garnet laser (PIPS) (15 roots/group). The bacterial reduction in the canal was determined by MTT assays. For measuring live versus dead bacteria in the dentinal tubules (4 teeth/group), teeth were split open and stained with LIVE/DEAD BackLight. Coronal, middle, and apical thirds of the canal dentin were scanned by using a confocal laser scanning microscope (CLSM) to determine the ratio of dead/total bacteria in the dentinal tubules at various depths. RESULTS: All 4 irrigation protocols significantly eliminated bacteria in the canal, ranging from 89.6% to 98.2% reduction (P < .001). XP Endo had the greatest bacterial reduction compared with other 3 techniques (P < .05). CLSM analysis showed that XP Endo had the highest level of dead bacteria in the coronal, middle, and apical segments at 50-µm depth. On the other hand, PIPS had the greatest bacterial killing efficiency at the 150-µm depth in all 3 root segments. CONCLUSIONS: XP Endo appears to be more efficient than other 3 techniques in disinfecting the main canal space and up to 50 µm deep into the dentinal tubules. PIPS appears to be most effective in killing the bacteria deep in the dentinal tubules.

Correlation Between Bacterial Endotoxin Levels in Root Canals of Primary Teeth and the Periapical Lesion Area.

PURPOSE: The purposes of this study were (1) to assess the endotoxin levels in root canals of primary teeth with necrotic pulps and periapical lesions; and (2) to evaluate the correlation of endotoxin levels with the periapical lesion size. METHODS: Twenty primary molars with necrotic pulps and periapical lesions were selected. Standardized radiographs were obtained and the lesions were measured. Material from each root canal was collected to quantify the bacterial endotoxin. The results were analyzed using Pearson's correlation, student's t test, and Fisher's exact test (α equals five percent). RESULTS: The initial amount of bacterial endotoxin in the root canals ranged from 0.089 to greater than 50.00 endotoxin units (EU)/mL and was detected in 100 percent of the samples. A positive but not significant correlation was observed between the amount of endotoxin and periapical lesion size in primary molars. CONCLUSION: Endotoxin was observed in 100 percent of root canals of primary teeth with a periapical lesion. However, there was no statistical significance between bacterial endotoxin levels and the periapical lesion area.

[Observation of oral Streptococcus oligofermentans colonization in rats].

OBJECTIVE: To study the colonization ability of Streptococcus oligofermentans (S. oligofermentan) in the condition of high sucrose in oral cavity of rats. METHODS: In this study, 48 SPF-SD rats aged 21 days were selected. From 24th to 27th days, the rats were fed with water of antibiotic and fed with high glucose diet continuously. On the 28th day, the rats were divided into four groups randomly, 12 rats per group. From the 28th day to 30th day, the first group (SM group) was inoculated with S. mutans, the second group (SO group) with S. oligofermentan, the third group (SO+SM group) with mixture of S. mutans and S. oligofermentan, the control group not with any bacteria. On the next day and the 10th day after inoculation of bacteria, the samples of dental plaque of the rats were acquired by scrubbing occlusal, buccal and lingual surfaces of bilateral mandibular molars with sterile swabs. The samples of SM group were inoculated on MSB and BHIS, of SO group on MSAE, of SO+SM group on MSB, MSAE and BHIS,of the control group on MSB and MSAE. S. mutans were screened and calculated on MSB, the suspected colonies of S. oligofermentan were screened and identified by the analysis of 16S rDNA. RESULTS: On the next day, the detection rate of S. oligofermentan was 33.3% (4/12) in the group of SO; in the group of SO+SM, the detection rate of S. oligofermentan was 0, the detection rate of S. mutans 100.00%, and the proportion of S. mutans 14.70%±4.53%; in the group of SM, the detection rate of S. mutans was 100.00%, the proportion of S. mutans 12.42%±4.27%. On the 10th day, in the group of SO, the detection rate of S. oligofermentan was 0; in the group of SO+SM, the detection rate of S. oligofermentan was 0, the detection rate of S. mutans 100.00%, and the proportion of S. mutans 15.78%±5.10%; in the group of SM, the detection rate of S. mutans was 100.00%,and the proportion of S. mutans 17.08%±5.75%. CONCLUSION: In the condition of the experiment where high glucose was maintained in the oral cavity in rats, S. oligofermentan appeared transiently and couldn't colonize in the rats.

Improved secondary caries resistance via augmented pressure displacement of antibacterial adhesive.

The present in vitro study evaluated the secondary caries resistance potential of acid-etched human coronal dentin bonded using augmented pressure adhesive displacement in conjunction with an experimental antibacterial adhesive. One hundred and twenty class I cavities were restored with a commercial non-antibacterial etch-and-rinse adhesive (N) or an experimental antibacterial adhesive (A) which was displaced by gentle air-blow (G) or augmented pressure air-blow (H). After bonding and restoration with resin composite, the resulted 4 groups (N-G, N-H, A-G and A-H) were exposed to Streptococcus mutans biofilm for 4, 8, 15, 20 or 25 days. The development of secondary caries in the bonding interface was then examined by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Data acquired from 15, 20 and 25 days of artificial caries induction were analyzed with three-way ANOVA at α = 0.05. The depth of the artificial carious lesions was significantly affected by "adhesive type" (Single Bond 2 vs experimental antibacterial adhesive p = 0.003), "intensity of adhesive displacement" (gentle vs augmented-pressure adhesive displacement; p < 0.001), as well as "artificial caries induction time" (p < 0.001). The combined use of augmented pressure adhesive displacement and experimental antibacterial adhesive reduces the progression of secondary caries.

Favourable effects of Bacillus subtilis and Bacillus licheniformis on experimental periodontitis in rats.

OBJECTIVES: The purposes of this study were to evaluate, in rats: i) the effects of Bacillus species on the development of experimental periodontitis (EP) via microtomographic, immunological and hematological assays (Experiment 1-E1); ii) the effects of Bacillus species as adjuncts to scaling and root planing (SRP) for the treatment of EP via histomorphometric and immunohistochemical analyses (Experiment 2-E2). METHODS: In E1, 24 rats were divided into groups C1 (control), PROB1, EP1 and EP-PROB1. In groups with EP, the mandibular first molar of each animal received a ligature for 14 days. In groups PROB1, animals received Bacillus species for 44 days, starting 30 days before EP induction in Group EP-PROB1. In E2, 24 rats were assigned to groups C2 (control), PROB2, EP-SRP2 and EP-SRP-PROB2. In groups with SRP, EP was induced as described in E1. The ligatures were removed after 14 days and SRP was performed. In groups PROB2, animals received Bacillus species for 15 days, starting after SRP in Group EP-SRP-PROB2. RESULTS: In E1, Group EP1 presented bone loss (BL) and eosinophil numbers greater than Group EP-PROB1 (P<0.05). In Group EP-PROB1, the receptor activator of nuclear factor-kB ligand (RANKL)/osteoprotegerin (OPG) ratio was similar to that of groups without EP. In E2, Group EP-SRP-PROB2 presented fewer TRAP-positive osteoclasts, lower immunolabeling pattern for a proinflammatory cytokine and decreased BL and attachment loss than Group EP-SRP2 (P<0.05). CONCLUSIONS: Bacillus species supplementation provided a protective effect against BL and enhanced the effects of SRP in the treatment of EP in rats.