In Vitro Evaluation of Mechanical Properties of Cention N and Its Comparison with Resin Modified Glass Ionomer Cement (RMGIC) Restorative Material as Used in Primary Teeth.

Methods: 22 specimens prepared with Cention and RMGIC were embedded in primary teeth mounted in acrylic for analysing shear bond strength. Shear bond strength was analysed using a universal testing machine. The modes of failure in samples were observed under a stereomicroscope and scanning electron microscope. 22 customised samples of Cention N and RMGIC were prepared and categorised as group A and group B, respectively. The flexural and compressive strengths of these samples were evaluated using a universal testing machine. Results: The shear bond strength of RMGIC was higher than that of Cention N, whereas the compressive and flexural strengths of Cention N were significantly higher than those of RMGIC. The modes of failure were predominantly adhesive followed by mixed failures. Conclusion: The results of this study suggest that Cention N demonstrated superior mechanical properties compared with RMGIC and can therefore be recommended for restorations in primary posterior teeth. Cention N being a smart, esthetic, self-cured, or dual-cured material with better mechanical properties offers a wide range of applicability in primary teeth.

Effect of in-office bleaching agent on the surface roughness and microhardness of nanofilled and nanohybrid composite resins.

Background: To compare the surface roughness and microhardness of Ceram.x® SphereTEC™ one and Filtek Z350 XT after in-office bleaching with Pola office. Methods: Twenty samples each of (10 mm diameter and 2 mm height) Ceram.x® SphereTEC™ one and Filtek Z350 XT were prepared. The samples were subjected to three bleaching sessions with 35% hydrogen peroxide (Pola office) with a seven-day interval between each session. Surface roughness and microhardness of the prepared samples prior to and after the bleaching regimen were measured using a profilometer and Vickers hardness tester, respectively. Results: A significant reduction (p <0.001) in the surface hardness of Filtek Z350 XT from 27.67 ± 2.10 to 17.83 ± 1.36 Vickers hardness number (VHN) was observed after the bleaching whereas no significant reduction in surface hardness was observed with Ceram.x® SphereTEC™ one. The adjusted mean (estimated marginal mean) microhardness after bleaching for Ceram.x ® SphereTEC™ one (35.79 ± 1.45) was significantly higher than Filtek Z350 XT (19.54 ± 1.45) (p < 0.001). However, in-office bleaching of these materials did not significantly alter their surface roughness. Conclusions: In office-bleaching with 35% hydrogen peroxide can reduce the microhardness of nanofilled composite. However, the surface roughness was not influenced by the bleaching procedure in both nanohybrid and nanofilled composite resin materials.

LASER as a tool for surface modification of dental biomaterials: A review.

In recent years, the application of lasers for modifying the surface topography of dental biomaterials has received increased attention. This review paper aims to provide an overview of the current status on the utilization of lasers as a potential tool for surface modification of dental biomaterials such as implants, ceramics, and other materials used for restorative purposes. A literature search was done for articles related to the use of lasers for surface modification of dental biomaterials in English language published between October 2000 and March 2023 in Scopus, Pubmed and web of science, and relevant articles were reviewed. Lasers have been mainly used for surface modification of implant materials (71%), especially titanium and its alloys, to promote osseointegration. In recent years, laser texturing has also emerged as a promising technique to reduce bacterial adhesion on titanium implant surfaces. Currently, lasers are being widely used for surface modifications to improve osseointegration and reduce peri-implant inflammation of ceramic implants and to enhance the retention of ceramic restorations to the tooth. The studies considered in this review seem to suggest laser texturing to be more proficient than the conventional methods of surface modification. Lasers can alter the surface characteristics of dental biomaterials by creating innovative surface patterns without significantly affecting their bulk properties. With advances in laser technology and availability of newer wavelengths and modes, laser as a tool for surface modification of dental biomaterials is a promising field, with excellent potential for future research.

Effect of Real-Time Environment on Mechanical Properties of Preformed Stainless Steel Archwires: An In Vivo Study.

Introduction: Clinicians should be aware of any effect the oral environment may have on archwires. Laboratory models fail to closely imitate intraoral conditions. The aim was to evaluate the change in mechanical properties of preformed stainless steel archwires after 15 weeks of exposure to the oral environment. Methods: Three commercially manufactured 0.019 × 0.025″ stainless steel archwires were evaluated. Young's modulus, yield strength, spring factor, and hardness were studied. The unexposed distal end cuts (control samples) and archwires were tested after 15 weeks of intraoral exposure (test samples). Tension tests, Vickers microhardness tests, and nanoindentation tests were carried out. Results: Normality was tested using the Shapiro-Wilk test. Statistical analyses included the paired t-test for intragroup comparisons and Kruskal-Wallis ANOVA with the post hoc Dunn test for comparison of mean percentage reduction in values. At T15, Young's modulus showed a statistically significant decrease. Changes in yield strength and spring factor were not significant for groups other than American Orthodontics wires. The reduction in hardness was significant in 3M Unitek. Vickers, tension, and nanoindentation tests demonstrated an expansive range between hardness and Young's modulus so determined. Conclusion: 3M Unitek archwires showed the highest difference in Young's modulus. Yield strength values increased in Ortho Organizers archwires. Spring factor decreased only in 3M Unitek archwires. Hardness values obtained from various tests did not produce identical results.

Effect of shape of titanium dioxide nanofillers on the properties of dental composites.

The main objective of the present study was to evaluate the effect of the morphology of titanium dioxide nanofillers on the flexural strength and shear bond strength of the dental composite. Spherical and rhombic-shaped nano titanium dioxide fillers were synthesized via solvothermal method and were characterized. Subsequently, these fillers were incorporated into a flowable composite (Filtek™ Z350 XT Flowable Restorative) at 0.5 wt.% and 1.5 wt.% and the prepared specimens were stored in water for 24 h. The specimens were then evaluated for flexural strength using a universal testing machine. Similarly, the shear bond strength of modified composites to the tooth was evaluated and bond failures were analyzed using stereomicroscope magnification. Incorporation of nanofillers significantly enhanced the flexural strength of flowable composite (p = 0.009) with a significant increase at 0.5wt.% of spherical (p = 0.015) and rhomboidal-shaped fillers (p = 0.010). However, no statistically significant difference in flexural strength was observed among the different shapes of nanofillers. The results of our study did not show a significant effect on the shear bond strength of the composites. Thus the reinforcing ability of titanium dioxide nanofillers on dental composite was confirmed in this study, although the effect of using nanofillers with different morphology was not significant.

An in vitro study of a custom-made device for thermoregulation of the mixing slab on the setting properties of zinc oxide eugenol impression paste.

Aim: The present study was aimed to investigate the functional relationship between the mixing temperature and properties of a commercially available zinc oxide eugenol impression paste (ZnOE paste). Settings and Design: In-vitro study. Materials and Methods: A custom-made simulated mixing device was indigenously designed to maintain different mixing temperatures, simulating cold, ambient, and hot weather. A commercially available ZnOE paste was mixed according to the manufacturer's instructions in the simulated mixing device at the temperatures ranging from 10°C to 50°C. Initial setting time and consistency were measured according to A. D. A. Specification No. 16 (n = 8). A stainless-steel die having 25, 50, and 75 µm lines was used for surface detail reproduction. Detail reproduction of the stone casts of the impressions was evaluated with a stereomicroscope at 30 magnification (n = 8). The shear bond strength of ZnOE paste to self-cure acrylic tray resin was measured by using the UTM at a crosshead speed of 0.5 mm/min (n = 8). Statistical Analysis Used: Data were analyzed by using one-way analysis of variance (ANOVA) and Tukey's post hoc tests at a confidence interval of 95% (alpha =0.05). Results: Initial setting time, consistency, and detail reproduction of the ZnOE paste were affected by the mixing temperature (P < 0.001). Mixing ZnOE paste at a lower temperature of 10°C and higher temperatures of 40°C and 50°C resulted in shorter initial setting time, thicker consistency, and poor detail reproduction. However, no significant difference was obtained in the shear bond strength among the different mixing temperatures evaluated (P > 0.05). Conclusion: Based on this in vitro study, it is advisable to perform the manipulation of ZnOE paste at a clinical/laboratory temperature of 30°C for optimum performance. The simulated mixing device used in this study can be an alternative for extreme climatic conditions.

Synthesis, characterization, and evaluation of quaternary ammonium-based polymerizable antimicrobial monomers for prosthodontic applications.

The present study aims to synthesize and characterize two quaternary ammonium (QAM) based monomers such as - dimethyl-hexadecyl-methacryloxyethyl-ammonium iodide (DHMAI) and 2-dimethyl-2-dodecyl-1-methacryloxyethyl ammonium iodine (DDMAI) and assess their cytotoxicity and antimicrobial properties. The study also aims to incorporate the optimized concentration of these monomers as copolymerizing monomers into conventional Polymethyl methacrylate (PMMA) denture base resin and evaluate their suitability for prosthetic applications. DHMAI and DDMAI monomers were synthesized through a Menschutkin reaction and their chemical structure was characterized using FT-IR and 1H-NMR spectroscopy. Cytotoxicity was determined using Methyl Thiazolyl Tetrazolium (MTT) assay whereas antimicrobial activity was assessed using the agar-disc diffusion method. Subsequently, optimized concentrations of DHMAI or DDMAI, based on the cytotoxicity results, were added to conventional PMMA resin. Antimicrobial activity, cytotoxicity, surface hardness, and water sorption of PMMA denture base rein incorporated with DHMAI or DDMAI were evaluated. FT-IR and 1H-NMR results confirmed the structure of monomers and copolymerization of DHMAI and DDMAI with PMMA resin. DHMAI and DDMAI monomers were found to be cytocompatible with mouse fibroblast cells up to a concentration of 5 µg/mL and 20 µg/mL respectively. In addition, incorporation of DHMAI or DDMAI at 5 µg/mL and 20 µg/mL respectively into PMMA denture base material did not affect their cytocompatibility. PMMA denture base resin incorporated with DHMAI or DDMAI significantly reduced the adhesion of microbes. Further, an increase in the surface hardness and a reduction in the water sorption was observed. Hence DHMAI and DDMAI can be considered as potential candidates for imparting antimicrobial activity to polymeric denture base materials.

Effect of Different Surface Treatments on the Micro-Shear Bond Strength and Surface Characteristics of Zirconia: An In Vitro Study.

Purpose: To study the effect of different surface treatments on the micro-shear bond strength and surface characteristics of zirconia. Methods: Two types of zirconia ceramics were tested: opaque (O) and translucent (T). Each type of zirconia was further allotted into four groups based on the type of surface treatment method. The four groups were: control (C), air abrasion with 110 µm Al2O3 particles (A), etching with Zircos-E Etching solution for 2 hours (E), and a combination of air abrasion and etching (AE). After the surface treatment, all specimens were ultrasonically cleaned and 10 resin cement cylinders were attached to the zirconia discs in each group. A micro-shear bond strength test was performed in a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture surfaces were assessed under a compound microscope. SEM, EDAX, and AFM analyses were done for the zirconia specimens after being subjected to surface treatment. Statistical analysis for the bond strength test was done using the Shapiro-Wilk test, one-way analysis of variance (ANOVA), and Post hoc Tukey test. Results: The micro-shear bond strength values for the groups were as follows in megapascals (MPa): OC 18.96 (5.54), OA 22.66 (2.51), OE 28.48 (4.50), OAE 28.63 (4.53), TC 22.82 (5.46), TA 25.36 (5.17), TE 28.12 (4.76), and TAE 32.00 (3.47). The one-way analysis of variance (ANOVA) and post hoc Tukey HSD tests were done which showed significant results in the groups. In opaque zirconia, significant differences were seen in the etching and air abrasion with etching groups when compared with the control and air abrasion groups. There was no difference between the etching and air abrasion with etching groups. For translucent zirconia, the only significant difference was seen in the air abrasion with etching group in comparison with the control and air abrasion groups. The mode of failure was majorly adhesive. The surface topography and surface roughness showed significant differences between the groups. The EDAX results showed material loss that occurred due to sandblasting in the air abrasion groups. Conclusions: Etching with Zircos-E Etching solution significantly increased the bond strength of zirconia to resin cement when compared with other surface treatment methods. In translucent zirconia, the best results can be achieved by combining etching with air abrasion.

Comparative evaluation of a bioactive restorative material with resin modified glass ionomer for calcium-ion release and shear bond strength to dentin of primary teeth-an in vitro study.

OBJECTIVES: This study aimed to evaluate the release of calcium ions from a bioactive restorative material and its shear bond strength (SBS) to primary dentin. STUDY DESIGN: Occlusal surface of extracted non-carious primary molars were flattened, onto which 2 × 2 mm cylinders of ACTIVA™ BioActive Restorative (PULPDENT® Corporation, Watertown MA) or Fuji II LC (GC Corporation, Tokyo, Japan) were prepared using a polypropylene straw mould. SBS of the materials to primary dentin was tested using a universal testing machine. The mode of bond failure was assessed using stereomicroscopy. 10 mm × 2 mm disks of each material were prepared and immersed in Milli-Q water for 1, 7, 14 and 21 days. The released calcium ions in the immersion media were quantified using Atomic Absorption Spectroscopy. RESULTS: ACTIVA™ BioActive Restorative showed a mean SBS of 4.29 ± 0.65 MPa to primary dentin and calcium ion release of 0.76 ± 0.12 ppm over 21 days. CONCLUSION: ACTIVA™ BioActive Restorative showed a significantly higher mean SBS to primary dentin, and significantly higher calcium ion release compared to Fuji II LC.

Effect of Chelating Agents on Push-Out Bond Strength of NeoMTA Plus to Root Canal Dentin

ABSTRACT Objective To evaluate and compare the effect of 17% Ethylenediaminetetraacetic Acid (EDTA), 9% Etidronic acid (HEDP), and 7% Maleic acid (MA) on the push-out bond strength of NeoMTA Plus sealer to the coronal, middle, and apical thirds of root canal dentin. Material and Methods Forty single-rooted human maxillary central incisors were selected and decoronated to 12 mm long root fragments. Working length was established and root canals were then enlarged up to rotary Protaper F3. After each instrumentation, the root canal was irrigated with 2.5% NaOCl. For the final irrigation regimen, the specimens were divided into 4 groups (n=10) and treated with EDTA, HEDP, MA or Saline. Root canals were coated with NeoMTA Plus sealer, and obturation was done with single cone obturation technique. Subsequently, three horizontal sections were taken from the coronal, middle and apical thirds of each specimen, and POBS was measured using a universal testing machine. The type of bond failures was assessed under a stereomicroscope. Statistical analysis was done with One-way ANOVA with Tukey's Post hoc analysis. Results MA and EDTA showed the highest POBS. There was no significant difference in bond strength between MA and EDTA (p>0.05). HEDP and Saline showed lower POBS. Among all the four groups, the coronal third showed the highest values, followed by middle and apical thirds. Conclusion The type of chelating agent used during the root canal treatment significantly affects the bond strength of NeoMTA Plus to the root canal dentin.

The effect of acid concentration and etch time on morphology and tensile bond strength of primary dentin: An in vitro study.

BACKGROUND: There are conflicting results concerning the ideal time for etching primary dentin and its effect on the bond strength of adhesive restorative materials. AIM: To assess in vitro, the effect of varied acid concentration and etch time on the morphological features and tensile bond strength of primary dentin. MATERIALS AND METHODS: Forty healthy primary molars were prepared by exposing the dentin of the occlusal surface, creating a smear layer. A 3 mm × 3 mm test indow was demarcated, and specimens were randomly allocated to four groups (n = 10): Group 1A 10% phosphoric acid, 7 s; Group 1B 10% phosphoric acid, 15 s; Group 2A 37% phosphoric acid, 7 s and Group 2B 37% phosphoric acid, 15 s. Surface analysis was done using atomic force microscope and scanning electron microscope. For tensile bond strength evaluation, 24 specimens prepared as mentioned were mounted in acrylic blocks and allocated to four groups according to the prescribed etching protocol. Resin rods were bonded and tested in tension after 24 h (n = 6). Data were analyzed statistically using unpaired t-test. RESULTS: Etching of primary dentin using 37% phosphoric acid for 7 s produced the highest tensile bond strength of 9.51 ± 2.19 MPa. CONCLUSION: Etching time of 7 s may improve the adhesion of resin restorative materials with primary dentin.

Simvastatin in polymer bioscaffold for bone regeneration. An in vitro and in vivo analysis.

OBJECTIVE: The study aimed to fabricate and test the biocompatibility of a polylactic-co-glycolic acid (PLGA) based guided tissue regeneration membrane impregnated with 'simvastatin' to promote sustained drug delivery near osseous defects and evaluate the regenerative potential of the membrane histologically. MATERIALS AND METHODS: We tested the mechanical properties and cytotoxicity of an indigenously fabricated PLGA membrane incorporated with simvastatin (1 mg/cm2). An animal study evaluated the regenerative potential of the membrane. Twenty-four adult Wistar rats, approximately 175 g in weight, were used in this study. The rats were divided randomly into four groups based on the postoperative healing periods into ten days, 1, 3, and 6 months. Within each time group, six rats were divided into three subgroups: Subgroup A - sham surgery controls; Subgroup B - PLGA without Simvastatin; Subgroup C - PLGA with simvastatin tests. The radiographic examination intervals were ten days, 1 and 3 months, while the histological assessment was around 1, 3, and 6 months. RESULTS: Simvastatin content was distributed uniformly in all the prepared membranes and was equivalent to 1 mg/cm2. 100 mg PLGA membrane with simvastatin demonstrated uniform drug release over time, excellent mechanical properties, and biocompatibility. The rat models in Subgroup C had better bone tissue formation radiographically and histologically. CONCLUSION: The study suggested that 'PLGA with Simvastatin' has the requisite properties to serve as a third-generation barrier membrane with the potential for local drug delivery.

Effect of polishing technique and immersion in beverages on color stability of nanoceramic composites.

BACKGROUND: Polishing of dental composite restorations to achieve a highly smooth and reflective surface not only enhances esthetics but also their color stability and improves resistance to staining. The objective of this study was to evaluate the effect of beverages on the color stability of nanoceramic composites polished using different techniques. METHODS: 80 samples of ceram. X SphereTEC one were prepared by condensing the material into a stainless-steel split mold and divided randomly into two groups. Group I was subjected to polishing using Sof-Lex system™ disks, and Group II was kept unpolished. Each group was subdivided into four sub-groups of 10 samples each. Each subgroup samples were immersed into designated beverages (Tropicana orange juice, Coco-cola, Nescafe coffee, and distilled water) for a duration of 15mins/day for 15 days. The color of all specimens before immersion, one day, and 15 days after immersion was measured using a Spectrophotometer. RESULTS: Significant staining of the material was found with cola drinks and coffee compared to orange juice and distilled water. Polished material showed better resistance to staining by various beverages compared to control group. CONCLUSION: Nanoceramic composites exhibited superior color stability after polishing with Sof-Lex system™. Among the beverages, coco-cola significantly altered the color of the composite.

Effect on Physical and Mechanical Properties of Conventional Glass Ionomer Luting Cements by Incorporation of All-Ceramic Additives: An In Vitro Study.

INTRODUCTION: Glass ionomer cements (GICs) are commonly used for cementation of indirect restorations. However, one of their main drawbacks is their inferior mechanical properties. AIM: Compositional modification of conventional glass ionomer luting cements by incorporating two types of all-ceramic powders in varying concentrations and evaluation of their film thickness, setting time, and strength. Material & Methods. Experimental GICs were prepared by adding different concentrations of two all-ceramic powders (5%, 10, and 15% by weight) to the powder of the glass ionomer luting cements, and their setting time, film thickness, and compressive strength were determined. The Differential Scanning Calorimetry analysis was done to evaluate the kinetics of the setting reaction of the samples. The average particle size of the all-ceramic and glass ionomer powders was determined with the help of a particle size analyzer. RESULTS: A significant increase in strength was observed in experimental GICs containing 10% all-ceramic powders. The experimental GICs with 5% all-ceramic powders showed no improvement in strength, whereas those containing 15% all-ceramic powders exhibited a marked decrease in strength. Setting time of all experimental GICs progressively increased with increasing concentration of all-ceramic powders. Film thickness of all experimental GICs was much higher than the recommended value for clinical application. CONCLUSION: 10% concentration of the two all-ceramic powders can be regarded as the optimal concentration for enhancing the glass ionomer luting cements' strength. There was a significant increase in the setting time at this concentration, but it was within the limit specified by ISO 9917-1:2007 specifications for powder/liquid acid-base dental cements. Reducing the particle size of the all-ceramic powders may help in decreasing the film thickness, which is an essential parameter for the clinical performance of any luting cement.

Comparison of shear bond strength of light cure mineral trioxide aggregate and light cure calcium hydroxide with nanofilled composite: A stereomicroscopic and scanning electron microscope analysis.

OBJECTIVE: The quest for ideal pulp capping materials has given rise to the development of newer materials such as light cure mineral trioxide aggregate (MTA). The bond strength of the pulp capping materials with overlying restoration is one among the several factors that are critical for the success of vital pulp therapy. Hence, we conducted this study to evaluate and compare the shear bond strength (SBS) of light cure MTA and light cure calcium hydroxide with nanofilled composite. MATERIALS AND METHODS: Thirty acrylic blocks each with a central hole were prepared to uniform dimensions and randomly distributed into two equal groups. In Group I, light cure MTA, and in Group II, light cure calcium hydroxide was used as pulp capping materials. After the application of adhesive system, nanofilled composites were applied onto the pulp capping material using a cylindrical plastic matrix. The SBS was tested on a universal testing machine (Instrom 3366, UK) at a crosshead speed of 0.5 mm/min. The samples were examined under stereomicroscope and scanning electron microscope to analyze different modes of failure. RESULTS: The results were statistically analyzed using independent sample t-test. Light cure MTA attained the mean SBS of 6.54 MPa and light cure calcium hydroxide attained the mean SBS of 6.56 MPa. There was no significant difference statistically in SBS of both the materials (P < 0.05). The modes of failure were predominantly mixed failure followed by cohesive failure within the restorative material in both Group I and II. CONCLUSION: The results of the study suggest that the SBS of light cure MTA and light cure calcium hydroxide is comparable. The modes of failure analyzed in both light cure MTA and light cure calcium hydroxide are not significantly different statistically. Hence, both materials can be successfully used as pulp capping material with nanofilled composite.

Comparative evaluation of the depth of cure and surface roughness of bulk-fill composites: An in vitro study.

BACKGROUND: Composites are in great demand due to the esthetic needs of the patients, which explains a wide variation in the types of available composites. However, the mechanical strength of the materials is questionable. Therefore, the mechanical properties of the newly available bulk-fill composites have been tested. OBJECTIVES: The main objective of the study was to compare the depth of cure (DOC) and surface roughness of 3 different bulk-fill composites: X-tra fil® (XTF), Tetric EvoCeram® Bulk Fill (TEC) and Beautifil® Bulk Restorative (BBR). MATERIAL AND METHODS: Fifty-seven (n = 19 in each group) samples were made using brass molds. All samples were subjected to Vickers hardness testing and profilometry. The one-way analysis of variance (ANOVA) test was used for the data analysis, followed by Tukey's post hoc test. RESULTS: The differences in the mean surface microhardness values of the materials were statistically significant (p < 0.001), with XTF showing the highest value. The TEC composite showed a higher surface roughness as compared to BBR and XTF. CONCLUSIONS: The results of the present study indicate that variations in the filler size and amount significantly influence the DOC and surface roughness of dental composites. Among the tested composites, the multi-hybrid composite exhibited superior DOC (XTF), whereas the nanohybrid composite exhibited superior surface finish (TEC).

The effects of recasting on the cytotoxicity of dental base metal casting alloys.

AIM AND OBJECTIVES: In dentistry, base metal casting alloys are extensively used for the fabrication of inlays, onlays, crowns, bridges, partial dentures, etc. During the casting of these alloys, excess amount of material used than needed will be collected as sprue buttons at the end, which is either added to the fresh alloy during casting and reused or disposed of. MATERIALS AND METHODS: The aim of the present in vitro experimental study was to investigate the effect of the complete recasting of four commercially available cobalt-chromium (Co-Cr) and nickel-chromium (Ni-Cr) base metal casting alloys on their cytotoxicity. During the study, four groups of alloys were subjected to complete recasting up to twenty times without the addition of new alloy. The cytotoxicity assessment of the selected alloys after recasting (Co-Cr and Ni-Cr alloys) was carried out using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. RESULTS: The results indicated that Co-Cr alloys exhibit superior cell viability compared to Ni-Cr alloys, and cytotoxic potential of the alloys increased with repeated casting and led to increased cell death. The recasting of alloys in the present study did not show high cytotoxicity even after the 20th recasting. CONCLUSION: From the results of the present study, it can be concluded that the alloys generated as a waste in the dental laboratory can be safely reused up to five times or at least once before they can be disposed, which reduces the cost of the treatment and also helps in conserving the natural resources.

Effect of Thermocycling on the Colour Stability of Aesthetic Restorative Materials: An in-vitro Spectrophotometric Analysis

Abstract Objective: To compare the color stability of Cention N, Fuji IX GP Extra, and Fuji IX GP after thermocycling. Material and Methods: Ten discs of each material of dimension 10 x 1 mm were prepared using a split mold. The preparations of the specimens were done according to the powder/liquid ratio as recommended by the manufacturers [4.6:1, 3.4:1 and 3.6:1 for the groups I, II, and III, respectively]. After setting, the samples were retrieved, and the thickness of each specimen was measured using a micrometer at five different locations. The specimens with variations in thickness, porosity or cracks were discarded and thus not included in the study. The selected specimens were stored in distilled water for 24 hours prior to testing. The prepared specimens were thermocycled at 5°C and 55°C, with a dwell time of 15 seconds for 250 or 500 cycles. Subsequently, the color parameters of the discs were measured using a spectrophotometer. The data were analyzed using two way ANOVA test, and a p-value <0.001 was considered. Results: Thermocycling resulted in changes in the color of both Glass Ionomer cement and Cention N (p<0.001). Among the materials tested, Cention N showed superior color stability. Conclusion: Cention N exhibited better color stability compared to Glass ionomer cements.

Fracture resistance of teeth obturated with two different types of mineral trioxide aggregate cements / Resistência à fratura de dentes obturados com dois tipos diferentes de cimentos agregados de trióxido minera

Objective: Endodontically obturated teeth have lower fracture resistance depending on the obturating material and technique. The purpose of this study was therefore to evaluate the influence of ProRoot MTA (Dentsply Sirona, Tulsa Division) and OrthoMTA III (BioMTA, Daejeon, Korea) as an obturating material on the fracture resistance of endodontically treated teeth. Material and Methods: Thirty extracted human maxillary central incisors were decoronated and instrumented using Protaper instruments (size F5). Irrigation was performed with 2.5% sodium hypochlorite between each instrument change followed by 7% maleic acid for one minute. Finally, canals were flushed with 5 ml of PBS solution for one minute. Samples were then divided into three groups. Group I- positive control (no root canal filling); Group II- obturation with ProRoot MTA; Group III- obturation with OrthoMTA III. Ten teeth were randomly selected as a negative control in which no treatment was performed. All the specimens were then subjected to fracture strength testing using universal testing machine. For evaluation of biomineralization, six maxillary central incisors were divided into two groups. Group I obturated with ProRoot MTA and group II obturated with OrthoMTA III. These samples were subjected to SEM analysis. Results: Positive control group demonstrated the least fracture resistance, while OrthoMTA III group showed the highest fracture resistance. There was no significant difference between negative control group and ProRoot MTA groups (p=0.821). OrthoMTA III group showed better tubular biomineralization when compared to ProRoot MTA. Conclusions: Root canals obturated with OrthoMTA III had better fracture resistance and increased tubular biomineralization compared to ProRoot MTA. Since root canals obturated with OrthoMTA III had better fracture resistance, it can be used as a promising obturating material.(AU)

Objetivo: Dentes obturados endodonticamente apresentam menor resistência à fratura, dependendo do material e da técnica de obturação. Portanto, o objetivo deste estudo foi avaliar a influência do ProRoot MTA (Dentsply Sirona, Tulsa Division) e OrthoMTA III (BioMTA, Daejeon, Coréia) como material obturador na resistência à fratura de dentes tratados endodonticamente. Material e Métodos: Trinta incisivos centrais superiores humanos extraídos foram decoronados e instrumentados com instrumentos Protaper (tamanho F5). A irrigação foi realizada com hipoclorito de sódio a 2,5% entre cada troca de instrumento, seguida por ácido maleico a 7% por um minuto. Finalmente, os canais foram lavados com 5 ml de solução de PBS por um minuto. As amostras foram então divididas em três grupos. Grupo I - controle positivo(sem preenchimento do canal radicular); Grupo II - obturação com ProRoot MTA; Grupo III -obturação com OrthoMTA III. Dez dentes foram selecionados aleatoriamente como controle negativo, no qual nenhum tratamento foi realizado. Todas as amostras foram então submetidas atestes de resistência à fratura usando uma máquina de teste universal. Para avaliação da biomineralização, seis incisivos centrais superiores foram divididos em dois grupos: grupo Iobturado com ProRoot MTA e grupo II obturado com OrthoMTA III. Essas amostras foram submetidas à análise SEM. Resultados: O grupo controle positivo demonstrou a menor resistência à fratura, enquanto o grupo OrthoMTA III apresentou a maior resistência à fratura. Não houve diferença significativa entre o grupo controle negativo e os grupos ProRoot MTA (p= 0,821). O grupo OrthoMTA III apresentou melhor biomineralização tubular quando comparado ao ProRoot MTA. Conclusões: Os canais radiculares obturados com OrthoMTA III apresentaram melhor resistência à fratura e maior biomineralização tubular em comparação como ProRoot MTA. Como os canais radiculares obturados com OrthoMTA III apresentaram melhor resistência à fratura, podendo ser utilizado como um material obturador promissor.(AU)

Effect of silver diamine fluoride-potassium iodide and 2% chlorhexidine gluconate cavity cleansers on the bond strength and microleakage of resin-modified glass ionomer cement.

BACKGROUND: Disinfection of the prepared cavity can be a crucial step in the longevity of restorations. The objective of this study was to compare the antimicrobial action (AMA) of silver diamine fluoride-potassium iodide combination (SDF-KI) with 2% chlorhexidine gluconate (CHX) and to compare the alteration in bond strength and microleakage while using SDF-KI and CHX as cavity cleansers in resin-modified glass ionomer cement (RMGIC) restorations. MATERIALS AND METHODS: Samples were grouped as follows: Group 1: Polyacrylic acid (PAA), Group 2: CHX, Group 3: SDF-KI, and Group 4: Distilled water (CTRL). AMA was assessed by measuring the zone of inhibition of the above-mentioned materials by dispensing them into the punch hole prepared on agar plates with an inoculum of Streptococcus mutans. For assessing the effect of the cavity cleansers on the bond strength of RMGIC, they were applied to the dentinal samples prepared from freshly extracted noncarious molars. After the surface was treated, cylindrical restoration of RMGIC was placed and allowed to set. The shear bond strength was then evaluated using a universal testing machine. Rhodamine-B dye penetration was viewed under a fluorescent microscope to evaluate the microleakage of RMGIC following surface treatment of the standardized cavities prepared on the cervical third of freshly extracted noncarious premolars. RESULTS: SDF-KI (34 ± 0.8 mm) showed potent AMA followed by CHX (23.9 ± 0.7 mm) and PAA (12.7 ± 0.8 mm). SDF-KI showed a drastic increase in the bond strength when compared to the PAA, CHX, and CTRL groups. Although the application of SDF-KI showed the least microleakage among all the groups, it was not statistically significant. CONCLUSION: The application of SDF-KI and CHX is useful against S. mutans in an in vitro study. Although SDF-KI group showed the least microleakage among the groups, it was not statistically significant. SDF-KI application has shown a drastic increase in the bond strength of RMGIC although further research is required for the suitable reasoning of the phenomenon.