Effect of precooling injection site and cold anesthetic administration on injection pain, onset, and anesthetic efficacy in maxillary molars with symptomatic irreversible pulpitis: a randomized controlled trial.

OBJECTIVE: This randomized controlled clinical trial assessed the analgesic and anesthetic effects of precooling the injection site and administration of refrigerated 2% lignocaine HCl with 1:100,000 epinephrine (LE) in maxillary molars with symptomatic irreversible pulpitis (SIP). MATERIALS AND METHODS: Sixty patients diagnosed with SIP (preoperative pain score ≥ 85 mm) in maxillary first molars were randomly allocated to two groups. In group I (control), topical gel was applied for a minute followed by conventional LE infiltration, whereas in group II (experimental), topical ice application for 15 s and refrigerated (4-6 °C) LE administration was done prior to endodontic treatment. The primary outcome measure was anesthetic efficacy that was defined as none to weak pain (≤ 36 mm) as measured on Heft Parker visual analog scale (HP-VAS) following access cavity preparation. Pain on injection and onset constituted the secondary outcome measures. The pain on injection was measured using HP-VAS, whereas the onset of anesthesia was assessed using an electric pulp tester (EPT) which was applied on the experimental tooth every minute until no response was elicited. Mann-Whitney U test was performed to analyze the data (p < 0.01). RESULTS: Experimental group reported a success rate of 86.6% when compared to control group (26.6%) and a statistically significant reduction on injection pain (20.0 mm vs 54.5 mm) (p < 0.01). The onset of anesthesia for experimental group was 2.4 min which was also significantly lower than control group (4.5 min) (p < 0.01). CONCLUSIONS: Cryotherapy can serve as an effective alternative to conventional anesthesia for achieving success, reduced pain, and faster onset during endodontic treatment of maxillary molars with SIP. CLINICAL RELEVANCE: Precooling the injection site and cold LE administration can result in effective pulpal anesthesia during endodontic management of maxillary molars in SIP patients.

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.

Current trend of restoration of endodontically treated teeth with extensive subgingival caries: A case series.

Endodontically treated teeth (ETT) are structurally and esthetically compromised. Conventionally, after endodontic therapy, the tooth is restored with full-coverage crowns to improve their fracture resistance and ensure their long-term success rate. However, the tooth preparation required for these restorations can result in the significant loss of enamel and dentin. The periodontal health will be affected if the margin of prosthesis is extended subgingival. Restoring ETT using minimally invasive methods is an effective way to preserve the remaining tooth structure. This case series show cases restoration of four endodontically treated mandibular first molars with extensive subgingival caries restored with short fiber-reinforced composite resin (everX Posterior, GC Europe N.V. Interleuvenlaan, Leuven), with 2-year follow-up.

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.

Depth of Penetration and Antimicrobial Activity of 5% and 10% Bamboo Salt, 2% Chlorhexidine Gel and Calcium Hydroxide Against Enterococcus faecalis - An In Vitro Study.

OBJECTIVE: E. faecalis is one of the most commonly found species in persistent and secondary infections associated with endodontic failure. This in vitro study aimed to evaluate the depth of penetration and antimicrobial efficacy of 5% and 10% bamboo salt (BS), 2% chlorhexidine gel (CHX) and calcium hydroxide (CH) against E. faecalis. METHODS: E. faecalis was inoculated in dentine blocks for 21 days following which the antibacterial efficacy of the experimental medicaments were quantatively assessed by harvesting the dentinal debris from depths of 200 µm and 400 µm from the block lumen on the 2nd and 7th day. The depth of penetration of the medicaments was measured using LIVE/DEAD BacLight stain under CLSM. RESULTS: Results showed that the medicaments had varying degrees of antimicrobial efficacy and depth of penetration. Among the medicaments, CHX showed the highest antimicrobial activity on both the time intervals (P<0.05), followed by 10% BS, 5% BS and the least efficacy was observed in CH group. CHX and 10% BS exhibited the highest depth of penetration, which was proximate to the penetration of E. faecalis. CONCLUSION: It can be concluded that 10% bamboo salt can serve as a viable natural antimicrobial in endodontic therapy.

Anti-inflammatory efficacy of petasin-incorporated zinc oxide eugenol sealer - An in vivo zebrafish study.

Background: The eugenol from zinc oxide eugenol (ZnOE) sealer tends to diffuse to the periapical region resulting in inflammation. Several modifications of ZnOE sealer have been formulated to minimize the inflammatory potential of the ZnOE sealer. Petasites hybridus contains petasin which possesses anti-inflammatory property used in treatment of migraine and allergic rhinitis. Aim: The aim of the study was to evaluate the anti-inflammatory property of petasin-incorporated ZnOE sealer on zebrafish. Materials and Methods: The study has been reviewed and approved by the Institutional Review Board (SRMU/MandHS/SRMDC/2018/S/025) and by the in-house Institutional Animal Ethics Committee (IAEC) of Pentagrit Research Lab and conducted with compliance to ICH harmonization and principles for animal housing and handling (IAEC Study No: 215/Go06/IAEC). The samples were implanted in the caudal portion of the zebrafish. The samples (n = 50) were divided into five groups (n = 10) - Group 1: incision only (negative control), Group 2: zinc oxide (ZnO) (positive control), Group 3: ZnO + eugenol and petasin in ratio of 10:1, Group 4: ZnO + eugenol and petasin in ratio of 5:1, and Group 5: ZnO + eugenol and petasin in ratio of 1:1. The experimental groups were further subdivided into two subgroups based on time intervals at 24 h and 48 h. The tissue samples were assessed using smear pathology test, and the percentage of inflammation was evaluated. The data were statistically analyzed using SPSS software version 22.0 with a significance level fixed as 5% (α = 0.05). Results: The presence of inflammatory cells and congestion of arterioles were taken as the criteria to assess inflammatory action. It was maximum in ZnOE sealer followed by ZnOE sealer modified with the addition of petasin to eugenol in the ratio of 10:1, 5:1, and 1:1, respectively. Conclusion: The addition of petasin extract to ZnOE reduces the inflammation potential of ZnOE sealers. ZnOE sealer containing eugenol and petasin in the ratio of 1:1 showed a maximal reduction in inflammation.

Push Out Bond Strength of a Glass Fibre Post to Root Dentine Pretreated with Proanthocyanidin and Phytosphingosine - An In Vitro Study.

OBJECTIVE: To evaluate the push out bond strength of a glass fibre post to root dentine pretreated with 6.5% proanthocyanidin (PAC) and 0.02% phytosphingosine (PHS). METHODS: Thirty-three freshly extracted single rooted human teeth were decoronated to a length of 14 mm. Root canals were prepared using rotary NiTi files and obturated with gutta percha and resin sealer. Post space was prepared using peeso reamers, retaining 5 mm of apical gutta percha. Following smear layer removal and acid etching of the post space, samples were randomly assigned to 3 groups based on the dentine pretreatment, namely the control (no pretreatment) group, 6.5% PAC group, and 0.02% PHS group. A glass fibre post was luted using a dual cure adhesive and luting cement. 1 mm thick root slices were sectioned from coronal, middle and apical levels of the post and their push out bond strength was evaluated using a universal testing machine. Data was analysed with one-way ANOVA and Games-Howell post hoc test (P<0.05). RESULTS: At all levels, PHS showed higher push out bond strength than PAC and control groups, with a significant difference between the experimental groups at the middle and apical thirds (P<0.05). The push out bond strength of PAC group was significantly higher than the control group in the coronal and apical thirds (P<0.05). CONCLUSION: Both PAC and PHS improved the push out bond strength of a glass fibre post to dentine.

Post-operative analgesia of 2% lignocaine with or without magnesium sulfate for inferior alveolar nerve block in symptomatic mandibular molars - a randomized double blind controlled clinical trial.

BACKGROUND: Single inferior alveolar nerve block is ineffective in achieving adequate pulpal anesthesia in 30-80% of patients due to anatomical variations, local tissue pH, central sensitization, and several factors. Various supplementary techniques and combination of adjuvants with lignocaine are used to overcome these failures. Magnesium sulfate (MgSO4), one such adjuvant, acts at the N-methyl-D-aspartate glutamate receptor resulting in effective anesthesia. The aim of this prospective, randomized, double-blind, clinical controlled trial was to evaluate the onset, anesthetic efficacy, duration and post-operative analgesia of 2% lignocaine with and without the addition of MgSO4 in patients with symptomatic irreversible pulpitis and apical periodontitis. METHODS: Fourty-two patients were randomly divided into three groups: 2% lignocaine (group 1) and 2% lignocaine with MgSO4 (75 mg) and (150 mg) in groups 2 and 3, respectively. Pre-operative vitals and Heft Parker-Visual Analogue Scale (HP-VAS) pain scores were recorded. The onset of anesthesia, anesthetic efficacy, and duration of anesthesia were evaluated post administration of the local anesthetic solution. The post-operative analgesia was examined at intervals of 2, 6, 12, 24, and 48 h. RESULTS: Administration of 150 mg MgSO4 hastens the onset of anesthesia (1.29 min) and produces better anesthetic efficacy (3.29 HP-VAS) compared to group 2 (2.07 min and 9.14 HP-VAS) and group 1 (3.29 min and 35.79 HP-VAS), respectively. The duration of anesthesia was significantly higher in group 3 (247.07 min) compared to that of groups 2 and 1 (190 min and 110.21 min) with P < 0.05. CONCLUSION: Combining 75 mg or 150 mg of MgSO4 with lignocaine is more effective than 2% lignocaine and 75 mg of MgSO4 is adequate for endodontic procedures.

Effect of Indigenously Developed Nano-Hydroxyapatite Crystals from Chicken Egg Shell on the Surface Hardness of Bleached Human Enamel: An In Vitro Study.

OBJECTIVE: The objective was to evaluate the effect of nano-hydroxyapatite (nHA) derived from chicken eggshell on bleached human enamel in comparison with commercial casein phophopeptide-amorphous calcium phosphate (CPP-ACP) paste using Vickers microhardness test. MATERIALS AND METHODS: nHA powder was prepared from chicken eggshell using combustion method. nHA slurry was prepared by mixing 1.8 g of nHA powder with 0.3 ml of distilled water. Forty intact maxillary anterior teeth were collected and decoronated, and the crowns were embedded in acrylic mold with the labial enamel surfaces exposed. Baseline microhardness evaluation was done (T0). The specimens were randomly divided into the following four groups (n = 10) based on the surface treatment of enamel: Group 1: no bleaching treatment; Group 2: bleaching with 30% hydrogen peroxide (HP) solution; Group 3: bleaching followed by the application of CPP-ACP; and Group 4: bleaching followed by the application of nHA. The specimens were stored in artificial saliva at 37°C for 2 weeks, after which they were subjected to Vickers microhardness test (T14). One-way ANOVA and Tukey's post hoc multiple comparison tests were used for statistical analysis (P < 0.05). RESULTS: Bleaching with HP significantly decreased the enamel microhardness. CPP-ACP and nHA derived from chicken eggshell increased the enamel microhardness significantly. There was no significant difference in microhardness values among the CPP-ACP and nHA groups. CONCLUSION: Nano-hydroxyapatite sourced from chicken eggshell was as effective as CPP-ACP in remineralizing and restoring the lost microhardness of bleached enamel.

Effect of proanthocyanidin and bamboo salt on the push-out bond strength of an epoxy resin sealer to sodium hypochlorite-treated root dentin: An in vitro study.

BACKGROUND: In endodontic therapy, final irrigation is often done with sodium hypochlorite (NaOCl). This jeopardizes the bond strength between the epoxy resin sealer, used subsequently in obturation and radicular dentin. This study aimed to analyze the effect of natural antioxidants, 6.5% proanthocyanidin (PA) and 25% bamboo salt (BS) on the reversal of NaOCl-induced reduced bond strength of an epoxy resin sealer to dentin. MATERIALS AND METHODS: Thirty-three single-rooted extracted human teeth were randomly divided into three groups based on the final irrigation protocol: group 1 (saline), Group 2 (6.5% PA), and Group 3 (25% BS). The canals were cleaned, shaped, and obturated with gutta-percha and AH Plus sealer. 1.5 mm-thick root slices made from coronal, middle, and apical thirds of the canal were subjected to push-out bond strength (PBS) testing. The data were statistically analyzed using Kruskal-Wallis and Dunn's post hoc test (P < 0.05). RESULTS: 5.25% NaOCl significantly decreased the bond strength of AH Plus to dentin (P < 0.05). Both 6.5% PA and 25% BS were capable of reversing the compromised PBS of AH Plus to NaOCl-treated dentin. CONCLUSION: Final irrigation with antioxidants such as PA and BS eliminates the risk of reduced bond strength of AH Plus to root canal walls, which ensues following the use of NaOCl as an irrigant.

Letter to the Editor.

Pain is an important aspect of pediatric dentistry. Phlenophobia or fear for needle is one of the significant factor for reduced apprehensiveness and decreased pain threshold in pediatric patients. How to cite this article: Balasubramanian SK, Gurucharan I, Sekar M. Letters to the Editor. Int J Clin Pediatr Dent, 2018;11(5):357-358.

Comparison of Acupuncture with Ibuprofen for Pain Management in Patients with Symptomatic Irreversible Pulpitis: A Randomized Double-Blind Clinical Trial.

Emergency pain management in symptomatic irreversible pulpitis commonly includes use of nonnarcotic analgesics. Acupuncture has been used in dentistry to alleviate pain after tooth extraction. The aim of this randomized, double-blind, placebo controlled clinical trial was to evaluate and compare the efficacy of acupuncture therapy and ibuprofen for pain management in such patients. A total of 157 patients participated in this study and were randomly assigned to three groups, Group I-classical acupuncture with placebo tablet, Group II-sham acupuncture with placebo tablet, and Group III-sham acupuncture with ibuprofen. Before commencement of the experiment, initial pain assessment was done using a HP-VAS scale. Treatment was done by first operator, while pain assessment was done by the second operator who was blinded to the procedure performed. Acupuncture needles were inserted for 15-20 minutes at acupoints for classical acupuncture and at nonacupoints for sham acupuncture. Posttreatment pain assessment was carried out at 15, 30, 45, and 60 minutes intervals. Follow-up analysis was recorded at 12, 24, and 48 hours using VAS verbal scale. The mean final HP VAS values for Group I showed statistically significant lower pain values when compared with groups II and III (p < 0.05), with no significant difference between groups II and III. Follow-up analysis showed Group I with higher percentage of no pain, which was statistically significant when compared with other two groups. It can be concluded that classical acupuncture is more effective in pain relief (faster and prolonged) than analgesics.

Comparison of the Effect of PRP, PRF and Induced Bleeding in the Revascularization of Teeth with Necrotic Pulp and Open Apex: A Triple Blind Randomized Clinical Trial.

INTRODUCTION: Treatment of a tooth with necrotic pulp and open apex is a special challenge to the clinicians. Apexification with calcium hydroxide and MTA barrier technique fails to induce continued root maturation which makes the tooth susceptible to root fracture. Hence, an ideal outcome for such a tooth should be regeneration of pulp like tissue into the root canal capable of continuing normal root maturation. AIM: This study aims to compare the effect of Platelet Rich Fibrin (PRF), induced bleeding technique and Platelet Rich Plasma (PRP) in the revascularization of tooth with necrotic pulp and open apex. The main objectives of the study were to: (a) Radiographically evaluate the continuation of root development, increase in the dentin wall thickness and narrowing of canal space, apical closure and resolution of the periapical lesion; and to (b) To clinically evaluate the response to pulp sensibility testing and response to percussion and palpation tests. MATERIALS AND METHODS: Sixty patients (6 to 28 years) with necrotic immature permanent tooth were randomly categorised into three groups after the root canal disinfection procedure. PRF as scaffolding material (Group A: n=20), revascularization with conventional induced bleeding technique (Group B: n=20), and PRP as the biomaterial (Group C: n=20). The primary outcome variable was measured using Periapical Index (PAI) (for periapical healing), Chen and Chen index (for apical responses), Schei's ruler (for root lengthening and root thickening) and other clinical parameters. The Chi-square test was used to interpret the data among the three groups at the end of 12 months for the variables root lengthening and lateral wall thickness. ANOVA test was performed to compare the mean of the PAI scores of the three groups at preoperative stage and 12 months. If statistically significant, Bonferroni test was done to compare the outcome among the three groups. The significant level was set at p<0.05. Kappa agreement was used to see whether the clinical criteria of success (asymptomatic) were in agreement with radiographic criteria. RESULTS: At the end of 12 months, patients presented with no pain and no signs of reinfection or no radiographic enlargement of the pre-existing apical pathosis in all the three groups. PRP was better than PRF and induced bleeding technique with respect to periapical wound healing when used in the regenerative endodontic procedures. The groups were comparable on grounds of root lengthening and lateral wall thickening. Type 3 apical response was the most common apical response in all the three groups. CONCLUSION: On analysing the pros and cons of the techniques performed, it is wise to establish induced bleeding technique as the standard endodontic procedure for revascularization of a non vital immature permanent tooth.

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.

Evaluation of dentinal tubule occlusion and depth of penetration of nano-hydroxyapatite derived from chicken eggshell powder with and without addition of sodium fluoride: An in vitro study.

AIM: This in vitro study evaluated the degree of dentinal tubule occlusion and depth of penetration of nano-hydroxyapatite (nHAp) derived from chicken eggshell powder with and without the addition of 2% sodium fluoride (NaF) using scanning electron microscope (SEM) and confocal laser scanning microscope (CLSM). MATERIALS AND METHODS: nHAp was synthesized and characterized using X-ray diffraction and SEM-energy dispersive spectroscopy. Dentin discs were obtained from extracted teeth, pretreated with 17% ethylenediaminetetraacetic acid for 5 min and were divided into four groups based on the experimental agents as follows: Group 1: Untreated (control), Group 2: 2% NaF, Group 3: nHAp, Group 4: Combination of nHAp and 2% NaF. The treatment protocol was carried out for 7 days, after which the specimens were viewed under SEM and CLSM. STATISTICAL ANALYSIS USED: One-way ANOVA and Tukey's post hoc multiple comparison tests (P < 0.05). RESULTS: All the experimental agents occluded the dentinal tubules, but to varying degrees and depths. Specimens treated with the combination of nHAp and 2% NaF showed complete dentinal tubular occlusion and significantly greater depth of penetration than those treated with nHAp and 2% NaF alone. CONCLUSION: The combination of nHAp and 2% NaF was the most effective in occluding dentinal tubules.

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.

Evaluation of post-surface conditioning to improve interfacial adhesion in post-core restorations.

AIM: To examine the influence of different post-surface treatments on the interfacial strength between epoxy resin-based fiber posts and methacrylate-based resin composites that are employed as core build-up materials. MATERIALS AND METHODS: Forty clear posts were divided into four groups of 10 each. The different surface treatments used were etching with alkaline potassium permanganate, 10% hydrogen peroxide, 37% phosphoric acid, and silanization alone. After etching and thorough rinsing, a single layer of silane was applied to the post surface. Then the post was placed in a rectangular plastic matrix and core bulid-up was done using Multi Core, a dual cured composite resin. A slab of uniform thickness, with the post in the center and the core build-up composite on either side was created. The specimens were cut so as to obtain microtensile sticks that were loaded in tension at a cross-head speed of 1 mm/min until failure. The statistical analysis was performed using two-way ANOVA and the paired T test for post-hoc comparisons. RESULTS: The results achieved with potassium permanganate had a significant influence on microtensile interfacial bond strength values with the tested material. CONCLUSION: Surface chemical treatments of the resin phase of fiber posts enhance the silanization efficiency of the quartz fiber phase, so that the adhesion in the post/core unit may be considered as a net sum of chemical and micromechanical retention.

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.