The evaluation of cytotoxicity and cytokine IL-6 production of root canal sealers with and without the incorporation of simvastatin: an invitro study.

BACKGROUND: Freshly mixed root canal sealers when proximate the periapical tissues, trigger varying degrees of cytotoxicity/inflammatory reactions. Simvastatin, a class of the drug statin, is a widely used cholesterol-lowering agent with additional anti-inflammatory activities. This study assessed the effects of simvastatin on cytotoxicity and the release of IL-6 (Interleukin-6) production when incorporated in zinc oxide eugenol and methacrylate resin-based sealers. METHODS: Experimental groups consisted of conventional zinc oxide eugenol and methacrylate based-EndoREZ sealers (ZE & ER respectively) and 0.5 mg/mL simvastatin incorporated sealers (ZES & ERS). L929 mouse fibroblast cells were exposed to freshly mixed experimental sealers and evaluated for cytotoxicity (MTT assay) and inflammation levels (inflammatory marker IL-6 for ELISA) at various time intervals (0h, 24h and 7th day). The values were compared to the cell control (CC; L929 cells alone) and solvent control (SC; L929 cells + DMSO) groups. All the experiments were conducted in triplicates and subjected to statistical analysis using IBM SPSS Statistics software. Non parametric tests were conducted using Kruskal-Wallis and Friedman tests for inter-group and intra-group comparisons respectively. Pairwise comparison was conducted by post hoc Dunn test followed by Bonferroni correction. P values < 0.05 were considered statistically significant. RESULTS: All the experimental groups (ZE, ER, ZES, ERS) exhibited varying degree of cytotoxicity and IL-6 expression compared to the control groups CC and SC. The cell viability for ZE and ER decreased on day 7 as compared to 24 h. ZES and ERS had higher viable cells (75.93% & 79.90%) compared to ZE and ER (54.39% & 57.84%) at all time periods. Increased expression of IL-6 was observed in ZE & ER (25.49 pg/mL & 23.14 pg/mL) when compared to simvastatin incorporated ZE & ER (ZES-12.70 pg/mL & ERS-14.68 pg/mL) at all time periods. Highest level of cytotoxicity and inflammation was observed in ZE compared to all the other groups on day 7. CONCLUSIONS: Addition of 0.5 mg/mL of simvastatin to the sealers (ZES and ERS) decreased the cytotoxicity in the freshly mixed state and reduces their inflammatory effect.

Fracture Resistance of Endodontically Treated Premolars Restored with Flowable Short Fibre-Reinforced Resin Composite-An In Vitro Study.

OBJECTIVE: This in vitro study aimed to evaluate the fracture resistance of endodontically treated premolar teeth restored with flowable short fibre-reinforced resin composite (FSFRRC) at varying depths within the root canals. METHODS: Fifty freshly extracted human single-rooted premolars were divided into 5 Groups (n=10), Group I (IN) intact teeth, Group II (P) restored coronally with resin composite only, Group III, IV and V (FSFRRC2, FSFRRC4, FSFRRC6) based on post space preparation to the respective depths of 2, 4 and 6 mm. Root canal treatment was performed for all the samples of Group II, III, IV, V and the teeth were decoronated 2 mm above cementoenamel junction. Following decoronation, post space preparation was done to the depths of 2, 4, and 6 mm (Group III, IV, V). Teeth were restored with FSFRRC (Groups III-V) intra-radicularly and coronally sealed using resin composite. All the teeth were subjected to fracture strength test using Universal testing machine, and mode of failure was analysed. Kruskal-Wallis test followed by Dunn Post-hoc test was conducted for statistical analysis. Statistical significance was set at P<0.05. RESULTS: All FSFRRC groups showed higher fracture resistance than teeth restored only with resin composite. FSFRRC4 and FSFRRC6 showed significantly (P<0.05) higher fracture resistance than intact teeth and other experimental groups. CONCLUSION: Intra-radicular placement of FSFRRC increased the fractured resistance significantly and may serve as a promising alternative to conventional post systems to rehabilitate endodontically treated teeth.

Identification of a novel bacterium Scardovia wiggsiae in high caries risk adolescence: A metagenomic and melt curve analysis.

Background: Mutans streptococci which comprise only 2% have long been presumed to be the specific pathogen responsible for caries. A novel caries associated bacterium namely Scardovia wiggsiae is recognized to be ecologically competitive in active caries lesions. The actual pathogen needs to be identified, so as to specifically target and reduce the prevalence of caries in a given community. Aim: The aim of the study is to evaluate the presence of S. wiggsiae in combination with other bacteria in caries risk adolescence. Methods: Sixty adolescent subjects were screened. Phase I-to determine the prevalence of S. wiggsiae in saliva, plaque and dentinal caries samples of low and high caries risk individuals (n = 30 each) using polymerase chain reaction (PCR); Phase-II-to identify its presence by 16SrRNA metagenomic analysis and quantitatively evaluate the cariogenic pathogen using high-resolution melt curve analysis and real-time PCR. Results: Highest prevalence of S. wiggsiae was observed in dentinal caries followed by plaque and saliva samples of high caries risk individuals under PCR analysis. Metagenomic analysis showed two-fold statistically increased presence of Lactobacilli and Bifidobacteriaceae (S. wiggsiae) in dentinal samples compared to plaque samples (P = 0.05). Mutans streptococcus recorded the minimum. Conclusion: Scardovia wiggsiae is identified as one of the predominant microorganism.

Ultramorphological characterization of the resin dentin interface--an in vitro analysis of nanoleakage patterns of dentin adhesives.

AIM AND DESIGN: The requirements of an effective dentin adhesive system include the ability to thoroughly infiltrate the collagen network and partially demineralized zone, to encapsulate the collagen and hydroxyapatite crystallites, to produce a well polymerized durable hybrid layer with high bond strengths. Microleak-age and marginal percolation are the most detrimental factors thwarting the success of any restoration. However the presence of leakage pathways, called nanoleakage have been observed in the hybrid layer, even in the absence of microleakage. The nanoleakage patterns of four dentin adhesives (Prime & Bond NT, AdheSE, Clearfil S3 bond and Fuji Bond LC) was compared using Scanning electron microscopy and Energy Dispersive Spectroscopy, by the silver nitrate penetration method. RESULTS AND CONCLUSION: The results indicated that etch and rinse adhesives showed the maximum nanoleakage followed by the self etch systems. The glass ionomer based bonding agents showed the least nanoleakage. It is extremely important to take nanoleakage as a consideration while choosing dentin adhesives, to ensure success of the restoration.

Fracture Resistance of Endodontically Treated Teeth Restored with 2 Different Fiber-reinforced Composite and 2 Conventional Composite Resin Core Buildup Materials: An In Vitro Study.

INTRODUCTION: The purpose of this in vitro study was to comparatively evaluate the fracture resistance of endodontically treated teeth restored with 2 fiber-reinforced composite resins and 2 conventional composite resin core buildup materials. METHODS: Sixty noncarious unrestored human maxillary premolars were collected, endodontically treated (except group 1, negative control), and randomly divided into 5 groups (n = 10). Group 2 was the positive control. The remaining 40 prepared teeth were restored with various direct core buildup materials as follows: group 3 teeth were restored with dual-cure composite resin, group 4 with posterior composite resin, group 5 with fiber-reinforced composite resin, and group 6 with short fiber-reinforced composite resin. Fracture strength testing was performed using a universal testing machine. The results were statistically analyzed by 1-way analysis of variance and the post hoc Tukey test. Fracture patterns for each sample were also examined under a light microscope to determine the level of fractures. RESULTS: The mean fracture resistance values (in newtons) were obtained as group 1 > group 6 > group 4 > group 3 > group 5 > group 2. Group 6 showed the highest mean fracture resistance value, which was significantly higher than the other experimental groups, and all the fractures occurred at the level of enamel. CONCLUSIONS: Within the limitations of this study, a short fiber-reinforced composite can be used as a direct core buildup material that can effectively resist heavy occlusal forces against fracture and may reinforce the remaining tooth structure in endodontically treated teeth.

Effect of Green and White Tea Pretreatment on Remineralization of Demineralized Dentin by CPP-ACFP-An Invitro Microhardness Analysis.

INTRODUCTION: Mechanical performance of dentine is of major significance for the overall function of the teeth. Remineralization of carious dentine is the ultimate goal in re-establishing the functionality of the affected tissue so as to regain and maintain the mechanical properties of dentine. Functional remineralization of the affected dentin involves stabilization of both inorganic and organic component, but Caesin Phosphopeptide Amorphous Calcium Flurophosphate (CPP-ACFP) stabilizes only inorganic content. Hence to stabilize organic content and to bring in functional remineralization the use of anticollagenolytic and antielastastic agent was considered for this study. AIM: To assess and compare the remineralization of artificial carious dentin pre treated with white and green tea, before and after application of CPP-ACFP using microhardness test. Null hypothesis was that both teas did not have any effect on remineralization potential of CPP ACFP. MATERIALS AND METHODS: Forty specimens were subjected to artificial caries lesions and were randomly divided into 4 groups based on the application of tea extract followed by CPP-ACFP (groups A & B) and CPP-ACFP followed by tea extracts (groups C & D). All the specimens were subjected to two pH cycling regimen. The specimens were subjected to Vickers microhardness test to obtain the microhardness values. The values were statistically analysed using one-way ANOVA and multiple comparisons with Tukey's HSD procedure. RESULTS: After the 1(st) and 2(nd) pH cycling in groups A and B, Group B showed significant increase in microhardness values (35.79± 3.12 VHN). But after the pH cycling regimen in groups C and D, microhardness values increased in 1(st) pH cycling (50.03± 3.64 VHN); (50.03±3.64 VHN), respectively but decreased during the 2(nd) pH cycling, (33.94±6.45 VHN); (33.11±6.11 VHN) respectively with the level of significance <0.05. CONCLUSION: The results of this study rejects the hypothesis tested and showed that both the tea extracts increased the microharness values when used prior to the application of remineralizing agent. However, 10% white tea showed better microhardness indicating stabilization of collagen in dentine resulting in functional remineralization.

Effect of various antioxidants on the shear bond strength of composite resin to bleached enamel: An in vitro study.

OBJECTIVE: The aim of this in vitro study was to evaluate and compare the effect of 10% sodium ascorbate, 6.5% proanthocyanidin, and 5% lycopene on the bond strength of composite resin to bleached enamel. MATERIALS AND METHODS: Labial enamel surfaces of 100 extracted human maxillary central incisors were used in this study. Twenty teeth served as group I (control) and received no bleaching treatment. The remaining 80 teeth were randomly divided into four groups of 20 teeth each, based on the antioxidant used as follows: group II- bleaching with 35% carbamide peroxide gel for 30 min without the use of an antioxidant, group III- bleaching followed by use of 10% sodium ascorbate solution, group IV- bleaching followed by use of 6.5% proanthocyanidin, and group V- bleaching followed by use of 5% lycopene. These groups were further subdivided into two subgroups of 10 teeth each, based on whether composite buildup was done immediately (subgroup A) or after a delay of 2 weeks (subgroup B) post bleaching. Shear bond strength of the specimens was tested under universal testing machine. The data were tabulated and statistically analyzed. RESULTS: Significantly higher shear bond strength values were observed in teeth treated with control group prior to bonding, followed by sodium ascorbate group. CONCLUSION: Within the limitations of this study, it can be concluded all the antioxidants used in this study increased the bond strength of bleached enamel. Among the antioxidant groups, sodium ascorbate showed significantly higher bond strength compared to proanthocyanidin and lycopene.

An in vitro evaluation of the effect of deep dry cryotreatment on the cutting efficiency of three rotary nickel titanium instruments.

CONTEXT: Cryogenic methods have been used to increase the strength of metals. AIM: The aim of this study was to evaluate the effect of deep dry cryotherapy on the cyclic fatigue resistance of rotary nickel titanium instruments. MATERIALS AND METHODS: Twenty K3, RaCe and Hero Shaper nickel titanium instruments, size 25, 0.06 taper, were taken for this study. Ten files were untreated (control group) and 10 files were deep dry cryogenically treated. Both the untreated and cryotreated files were subjected to cyclic fatigue evaluation. Cyclic fatigue was evaluated as the number of cycles it took for fracture of the instrument within a stainless steel shaping block of specific radius and angle of curvature. STATISTICAL ANALYSIS: Mean values were compared between different study groups by using one-way analysis of variance (ANOVA) with P < 0.05 considered as the level of significance. RESULTS: The results showed a significant increase in the resistance to cyclic fatigue of deep dry cryotreated NiTi files over untreated files. CONCLUSIONS: It may thus be concluded that deep cryotherapy has improved the cyclic fatigue of NiTi rotary endodontic files.

Degree of conversion of two dentin bonding agents with and without a desensitizing agent using fourier transform infrared spectroscopy: An in vitro study.

OBJECTIVE: This in vitro study investigated the effect of a desensitizer on the degree of conversion of two bonding resins using Fourier transform infrared (FTIR) spectroscopy. MATERIALS AND METHODS: An etch-and-rise bonding resin and a self-etching adhesive resin were selected for the study. Vivasens (Ivoclar Vivadent) was used as a desensitizing agent. Grouping was done as follows: Group I: Adper Single Bond (n=10), Group II: Adper Single Bond + Vivasens (n=10), Group III: AdheSE One (n=10), Group IV: AdheSE One + Vivasens (n=10). The bonding resin alone was light cured for 20 seconds in groups I and III. For groups II and IV, 1 ml each of the bonding resin and the desensitizer was mixed in a vial and light cured for 20 seconds. The specimens were analysed using FTIR spectroscopy. RESULTS: Group II (Adper Single Bond + Vivasens) showed a significantly higher degree of conversion compared to Group I (Adper Single Bond). Comparing Groups III and IV, Group IV (AdheSE One + Vivasens) showed a significantly higher degree of conversion compared to Group III (AdheSE One). CONCLUSIONS: The degree of conversion is increased when a dentin bonding agent is used along with a desensitizer. Hence, this combination can be recommended to effectively control postoperative sensitivity.

Duration-dependent susceptibility of endodontic pathogens to calcium hydroxide and chlorhexidene gel used as intracanal medicament: an in vitro evaluation.

The aim of this study was to evaluate the effective duration of antimicrobial activity of a calcium hydroxide-based medicament (Apex Cal) and 2% chlorhexidene gluconate gel against selected endodontic pathogens (Enterococcus faecalis, Candida albicans, Porphyromonas gingivalis, and Prevotella intermedia). The agar diffusion test was used to determine the antimicrobial activity. Chlorhexidene gluconate gel showed the largest inhibitory zones. The antimicrobial action of both medicaments decreased significantly with time, with calcium hydroxide showing no antimicrobial action after 72 hours. In conclusion, 2% chlorhexidene gel showed better antimicrobial activity than calcium hydroxide, and the effective antimicrobial action of both medicaments decreased after 48 hours.