Do different time intervals in placement of restorative materials over calcium silicate cements, affect interface microhardness of different restorative materials?

Objectives: The type of materials and application time of final restorations on calcium silicate cements (CSCs) are important factors which influence the interfacial properties. The aim of this study was to investigate the effect of different placement time of RMGI (Resin Modified Glass Ionomer), composite resin and amalgam over different CSCs on the surface microhardness of these restorative materials.Methods: Each CSCs material (Biodentine, MTA, CEM cement) was mixed and carried into a hole (6mm diameter ×4 mm thickness) in the center of 270 molds (n=90 /each CSC). Then these molds were randomly divided into three main experimental groups (n=30) in regard of restorative materials (Amalgam, RMGI, Composite) that were placed in the other molds with the same hole size to make restorative materials and CSCs in contact together. Afterwards, each experimental group was divided into three subgroups according to the time interval of restoration placement that was immediately, after 24h and after 72h (n=10). Two molds were separated from each other after one week storage in incubator with 100% humidity in 37 °C, in order to evaluate the Vickers microhardness of restorative materials in CSC-restorative material interface. Statistical analysis included two-way Anova followed by Post hoc Dunnett T3 in cases with lack of homogeneity and Tukey HSD in cases with homogeneity.(p=0.05)Results: The microhardness of all restorative materials was neither significantly influenced by the CSCs materials (p>0.05) nor by the timing of final restoration (p>0.05) except in RMGI in immediate contact with CEM cement. (p<0.001)Conclusion: Restorative materials hardness in interface with studied CSCs may not affect. This in vitro study found no evidence against immediate definitive restoration over CSCs.

The Effects of Various Restorative Techniques on the Fracture Resistance of Pulpotomized Permanent Premolars

Aim. This study aimed to evaluate the effects of various restorative techniques on the fracture resistance of pulpotomized premolars with mesioocclusodistal (MOD) cavities treated with mineral trioxide aggregate (MTA) or calcium enriched mixture (CEM) cement. Materials and Methods. One hundred and eight sound extracted maxillary premolars were randomly assigned to nine experimental groups (n = 12). The teeth in group 1 did not receive any preparation. Class II MOD cavities were prepared in the other experimental groups. In groups 2, 4, 6, and 8, tooth-colored MTA was used for pulpotomy. In groups 3, 5, 7, and 9, CEM cement was used for pulpotomy. Groups 2 and 3 were left unrestored. Groups 4 and 5 were restored with amalgam. Groups 6 and 7 were restored with a conventional composite resin, and groups 8 and 9 were restored with bulk-fill giomers. Fracture resistance was measured, the fracture pattern of each specimen was assessed, and the results were statistically analyzed. Results. The fracture resistance of group 1 was significantly higher than those of the other groups ( p < 0.05 ). The fracture resistance of group 2 (MTA + amalgam) was statistically lower than those of all experimental groups ( p values < 0.05) except groups 3, 4, and 5 ( p values > 0.05). No statistically significant differences were found between the groups restored with amalgam, conventional composite resin, and bulk-fill giomer (groups 4, 5, 6, 7, 8, and 9) ( p values < 0.05). The highest rate of mode 1 fracture (restorable fracture) was observed in group 1 followed by groups 8 and 9. Conclusion. No significant differences were found among the fracture resistances of the restored teeth using various restorative techniques. Bulk-fill giomers followed by conventional composite resin were better able to prevent unfavorable fractures compared to amalgam. Therefore, they seem to be more reliable for the restoration of pulpotomized teeth with MOD cavities.

Effects of various liquid-to-powder ratios on the compressive strength of calcium enriched mixture: Original research

Background. Calcium-enriched mixture (CEM) cement has been introduced and marketed as a biomaterial for use in furcal perforation repair and apexogenesis procedures, in which the compressive strength that indicates the material’s resistance against crushing is of utmost importance. This study evaluated the effect of various liquid-to-powder ratios on CEM cement’s compressive strength. Methods. One gram of the cement was mixed with 0.5, 0.34, and 0.25 mL of demineralized water and transferred to stainless steel molds (6 and 4 mm in height and diameter, respectively). Five cells in the mold were considered for each group. The compressive strength test was conducted using the universal testing machine after incubating for seven days under 95% humidity at 37°C. One-way ANOVA was applied for data analysis at P≤0.05 significance level. Results. The mean compressive strength in the liquid-to-powder ratios of 0.5, 0.34, and 0.25 were 3.4456, 3.2960, and 3.3485, respectively, with no significant differences between them. Conclusion. Under this study’s limitations, changing the liquid-to-powder ratio did not affect CEM cement’s compressive strength.

Short-term Effect of Four Root Filling Materials on the Flexural Strength of Human Root Dentin

Background: This study aimed to assess the effects of calcium hydroxide, Biodentine, calcium-enriched mixture (CEM) cement, and mineral trioxide aggregate (MTA) on root dentin flexural strength after a 30-day exposure period. Methods: This in vitro experimental study evaluated 25 freshly extracted sound human incisors with no caries or restorations. The apical 5 mm and the coronal two-thirds of the crowns were cut such that all samples had 10 mm length. Dentin samples (n=20 in each group) were then exposed to 2 mm thickness of calcium hydroxide, Biodentine, CEM cement, MTA, or saline (control) in petri dishes for 30 days. Finally, dentin samples were subjected to a three-point bending test after the intervention, and the flexural strength data were analyzed using one-way ANOVA, Tukey’s test, and t test. Results: Thirty-day exposure to all four biomaterials decreased the flexural strength of root dentin (P<0.05). The four groups were significantly different in terms of the flexural strength of root dentin (P=0.001). The flexural strength of root dentin was significantly lower following exposure to calcium hydroxide (P=0.003), Biodentine (P=0.011), CEM cement (P=0.001), and MTA (P=0.007) compared to saline. The reduction in strength following exposure to calcium hydroxide was higher than that in Biodentine, CEM cement, and MTA groups (P<0.05) while the latter three were not significantly different in this respect (P>0.05). Conclusions: In general, all four tested biomaterials decrease the dentin strength although this reduction is more prominent by calcium hydroxide.

Comparison of MTA, CEM Cement, and Biodentine as Coronal Plug during Internal Bleaching: An In Vitro Study

Background. Internal bleaching is a choice of treatment in discolored endodontically treated teeth. Cervical root resorption is one of the important complications of this treatment. A suggested procedure to prevent this type of resorption is using a coronal barrier under the bleaching materials. The aim of the study was to compare the microleakage of mineral trioxide aggregate (MTA), calcium-enriched mixture (CEM) cement, and Biodentine. Materials and Methods. In this in vitro study, a total of 60 single canal incisors were included. They were randomly divided into three experimental groups (n = 16), one positive control group (n = 6), and one negative control group (n = 6). Coronal portion of the canals in the experimental groups was sealed with 3 mm of MTA, CEM cement, or Biodentine as a coronal barrier. After 3 days, specimens were bleached. A fresh Enterococcus faecalis suspension was added to the samples. The culture tubes were observed for 45 days, and the daily turbidity was recorded. Statistical analysis was accomplished by the Kaplan–Meier test and SPSS 22. Results. All positive samples showed turbidity, whereas none of the negative samples allowed bacterial leakage. Results showed no significant difference between MTA, CEM cement, and Biodentine groups. ( P value = 0.304, 0.695, and 0.217). The bacterial microleakage for the two groups also did not show significant differences. Conclusions. CEM cement and Biodentine showed promising results as coronal plug, and clinical studies are needed to test these materials with MTA for avoiding microleakage in internal bleaching treatment.

Evaluation of the adhesion of human dental pulp stem cells to differentendodontic biomaterials before and after setting

Background. Stem cell-based treatment modalities have been potential strategies for tissue regenerationin many conditions. Several studies have evaluated the biologic properties of DPSCs and their efficacyin the treatment of a variety of diseases. The present study was undertaken to evaluate the adhesionbehavior of DPSCs on different endodontic materials before and after setting. Methods. The crowns of the selected teeth were removed, and the root canals were prepared andobturated with gutta-percha and AH26 sealer. A retrograde cavity was prepared at root ends. Differentmaterials were placed in the cavities. Then the samples were attached to the wells with the use of achemical glue. Dental pulp stem cells were allowed to proliferate to reach a count of 2 million andtransferred to -12well plates in association with a culture medium. Finally, the samples attached to thewells were exposed to the stem cells immersed in the culture medium before and after setting. Thenadhesion of the stem cells was evaluated using SEM. Results. The SEM results showed cellular adhesion in the samples containing CEM cement both beforeand after setting. The samples containing MTA Angelus and ProRoot MTA exhibited cellular adhesionbefore setting, with no cellular adhesion after setting. The samples containing AH26 and MTA Fillapexsealers exhibited cellular adhesion after setting, with no adhesion before setting. The samples containingsimvastatin exhibited no cellular adhesion before setting; this material had dissolved in the culturemedium after setting evaluation. Conclusion. The results of the present study showed that of all the materials tested, CEM cement hadthe highest capacity for dental pulp stem cell adhesion.

Chemical modification of MTA and CEM cement to decrease setting time and improve bioactivity properties by adding alkaline salts

Background . Mineral trioxide aggregate (MTA) and Calcium-enriched Mixture (CEM) cement are used for pulp capping since they induce the formation of a dentinal bridge. Long setting time is a shortcoming of these types of cement. This study aimed to assess the effect of the incorporation of some alkaline salts to MTA and CEM cement on their setting time, ion release profile, pH, and surface morphology. Methods. In this in vitro experimental study, 5% calcium chloride (CaCl2), calcium oxide (CaO), sodium fluoride (NaF), and calcium nitrate [Ca(NO3)2] were separately added to MTA and CEM cement. The primary and final setting times of the cements were measured using a Gillmore needle apparatus. The samples were immersed in simulated body fluid (SBF) for one, seven, and 14 days and subjected to x-ray diffraction (XRD) and scanning electron microscopy (SEM) for phase identification and surface morphology assessment. The change in the pH of solutions was studied, and the calcium ion release profile was determined using inductively coupled plasma atomic emission spectroscopy (ICP-AES). The data were analyzed with ANOVA, followed by post hoc tests. Results. CaCl2 and CaO decreased the setting time of MTA, and Ca(NO3)2 decreased the setting time of CEM cement. The incorporation of the salts increased the pH and calcium ion release from both cements, and hydroxyapatite deposits were noted to cover the surface of the samples (observed by SEM and confirmed by EDXA). Conclusion. The incorporation of CaCl2 and CaO into MTA and Ca(NO3)2 into CEM cement decreased their setting time and increased their pH and calcium ion release.

Fracture Resistance of Immature Incisors Following Root Filling with Various Bioactive Endodontic Cements Using an Experimental Bovine Tooth Model

Objective The aim of this study was to compare the fracture resistance of immature bovine roots when using ProRoot MTA, CEM Cement, and Biodentine as root filling materials. Materials and Methods An immature bovine tooth model was developed by removing the coronal and apical portions of 70 bovine incisors 8 mm above and 12 mm below the cementoenamel junction (CEJ). The specimens were then divided into five groups: ProRoot MTA, CEM Cement, Biodentine, gutta-percha/AH26 sealer, and control. All groups received a 5-mm apical plug with a temporary restorative material. Then, the remaining root canal space was filled with one of the afore-mentioned materials. After setting, the specimens were mounted in acrylic resin. Then, 3 mm coronal to the CEJ from the buccal side of the teeth and at a 135°angle to the long axis, the specimens were loaded until fracture. Results The specimens in the Biodentine (2196 N) and ProRoot MTA (2103 N) groups had significantly greater fracture resistance in comparison to the control group (p = 0.01). No significant difference was found between CEM Cement, gutta-percha and sealer AH26, and control groups. No significant differences occurred between the four experimental groups (p = 0.45). Conclusion Filling the root canal space with ProRoot MTA and Biodentine contributed to higher fracture resistance values.