Cytotoxicity effects of nanohybrid, bulk-fill, and ormocer composites on dental pulp stem cells and human gingival fibroblast cells.

Background: Despite significant improvements in the physical and esthetic properties of modern composite resins, there are still concerns about their biocompatibility. The aim of the current study was to evaluate the toxicity of X-tra fil, Grandio, and Admira Fusion composites on dental pulp stem cells (DPSCs) and human gingival fibroblast (HGF) cells. Materials and Methods: In this in vitro experimental study, 48 composite disks were made using Grandio, Admira Fusion (2 mm high and 4 mm in diameter), and X-tra fil (4 mm high and 4 mm in diameter) composites and cured for 40 s. The composite blocks were then crushed with a sterile mortar and dissolved in phosphate saline buffer solution. Tetrazolium salt (3-(4,5-dimethyl thiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT_, neutral red (NR) assay, flow cytometry, and quantitative real-time polymerase chain reaction (RT-PCR) tests (n = 5) were used to evaluate the toxicity of the composites on two cell types (HGF, DPSCs). Data were analyzed using one-way ANOVA test followed by Newman-Keuls test. Level of significance was set at P < 0.05. Results: According to the results of MTT test, only Grandio showed a significant cytotoxicity in DPSCs, but in HGF cells, Grandio and X-tra fil both showed a significant cytotoxicity. In NR test, Grandio and X-tra fil composites showed a significant cytotoxicity on both HGF and DPSC cells. RT-PCR test results on both DPSC and HGF cells indicated that bax gene expression in the Grandio composite was significant. In this test, the nonexpression of the bcl2 gene in DPSCs was significant in Grandio (100 and 200 µg/ml) and in X-tra fil (200 µg/ml). All of the tests performed in this study showed no significant toxicity of Admira fusion. Conclusion: Admira Fusion is suitable for oral cells in terms of biocompatibility and can be used as a suitable restorative material for deep restorations near the pulp or adjacent to the gums.

Evaluating the antibacterial effect of synthesized herbal toothpastes and their efficacy for dentine tubule occlusion: Scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis.

The tubule occlusion of two newly developed herbal toothpastes was examined. They were prepared based on the mixture of pomegranate peel and Equisetum arvense extracts with strontium acetate. The antimicrobial activity of pomegranate peel and E. arvense were determined using minimum inhibitory concentration (MIC). Then, 30 mid-coronal dentin discs from the human third molars were etched for 30 s with the lemon juice (pH = 2.4). The specimens divided into the three groups. While the control group had 6 specimens, Groups 1 and 2 were including 12 specimens. Group 1 brushed with toothpaste containing 10% strontium acetate and 5% hydroalcoholic extracts of pomegranate peel, and Group 2 brushed with 5% strontium acetate, 5% hydroalcoholic extracts of E. arvense, and 5% hydroalcoholic extracts of pomegranate peel. Brushing was simulated for 6 months with 2 N loading. Then, 50% of discs in each group were immersed in lemon juice for 1 min. Moreover, specimens in control group were brushed with distilled water. Finally, all 30 discs were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDXS). The occluded dentin tubules were counted and statistically evaluated. It was found that the number of open dentin tubules decreases significantly after brushing with both tested toothpastes compared with control group (p < .001). Moreover, a significant difference was observed between two toothpastes before and after acid immersion process (p < .001). The SEM micrographs confirmed the dentin tubule occlusion of both herbal dentifrices. Besides, EDXS analysis approved the strontium and silica presence on the dentin tubules for the toothpaste which was based on E. arvense.

Assessing the Knowledge of Students about Dental Bleaching in Shahid Bahonar University of Kerman, Iran.

STATEMENT OF THE PROBLEM: An attractive smile and white teeth give self-confidence and provide impression of health, which help individuals for social and interpersonal success. Increasing demand for tooth bleaching and lack of relevant information on the other hand, necessitate a new investigation to assess the knowledge of the students about dental bleaching in Kerman. PURPOSE: This study was designed to assess the overall knowledge of the students of Shahid Bahonar University of Kerman regarding dental bleaching and their tendency to perform it. MATERIALS AND METHOD: This cross-sectional study enrolled 384 students who were selected by simple random sampling. A valid and reliable self-administered researcher-made questionnaire was employed to collect data about demographic information, health behavior, tooth bleaching, and the tendency to perform . This tool contained 8 questions with the focus on the knowledge of dental bleaching. Data were analyzed by using SPSS version 21 and regression analysis at a significant level of 0.05. RESULTS: Overall, 59.55% of participants were male and 40.45% were female students. Most likely, the source for gaining information was internet. In this regard, 29 individuals were dissatisfied with tooth color, 27 ones with the appearance of teeth, 13.5% have done tooth bleaching, and 69% had tendency to do that. The preferred knowledge was about the difference between scaling and root planning (SRP) and bleaching. There was no significant difference between age, gender, and marital status variables with the knowledge of dental bleaching. Tooth color satisfaction increased the tendency to do bleaching about 1.87 times. CONCLUSION: The study highlights that 69 % of the students had a tendency to do the bleaching, their knowledge was moderate, and there was no statistical relationship between knowledge, gender, and marital variables. Color variable had an overall positive effect on the tendency to do the bleaching.

Dentists' Knowledge and Clinical Experience towards Molar-Incisor-Hypomineralization in Iran

ABSTRACT Objective: To determine the knowledge and clinical experience of dentists regarding MIH in Kerman/Iran. Material and Methods: In this cross-sectional study, a census sampling method was used, and all dentists registered in Kerman medical council were asked to participate in the study. A validated and reliable researcher administered questionnaire was used to determine participants' demographic characteristics, knowledge, and clinical experience. The association between knowledge score and demographic variables was determined using an independent t-test and ANOVA. The level of significance was set as 0.05. Results: Overall, 400 specialized and general dentists in Kerman completed the questionnaire. The mean knowledge score of dentists was 6.6±1.9 of 11. Female dentists' knowledge was higher than male dentists (p<0.05). General dentists had a higher level of knowledge regarding MIH compared to specialists (p<0.05). Overall, 79.5 % had been faced with MIH during their practice years. After confronting MIH teeth, 48.8% of dentists referred patients to specialists for treatment. Providing aesthetics was considered the most difficult part of treatment (43.2%). Resin composite was the most favorable dental material for treating MIH (60.9%). Conclusion: Although most dentists in Kerman had encountered MIH defects during their clinical practice, they did not have enough knowledge of the defect and required education on all aspects of MIH diagnosis and management. Younger dental practitioners, general dentists and females presented higher knowledge of MIH.

Histological Evaluation of Human Pulp Response to Direct Pulp Capping with MTA, CEM Cement, and Biodentine.

STATEMENT OF THE PROBLEM: Direct pulp capping (DPC) is an established method in which the exposed pulp is coated with a suitable material to prevent further damage and to help its repair and healing. Different proposed materials may have different impact on pulp response during this treatment. PURPOSE: The purpose of this study was to compare the response of human dental pulp after DPC with calcium-enriched mixture (CEM), mineral trioxide aggregate (MTA) cement, and Biodentine. MATERIALS AND METHOD: In this clinical trial study, class V cavities were prepared on the buccal surfaces of 30 human premolar teeth, until the pulps were mechanically exposed. Then, teeth were randomly pulp capped with MTA, CEM cement and Biodentine, followed by resin modified glass ionomer filling. The fourth group was the control group (n= 10), in which the teeth were extracted without any prior intervention. Six weeks after the intervention, the teeth were extracted and prepared for histological evaluation in terms of the type and degree of pulp inflammation, dentin bridge formation and the presence of necrosis. Data were analyzed using Kruskal-Wallis and Mann Whitney U tests. RESULTS: In all groups, necrosis was not observed and inflammation was chronic. The Biodentine group exhibited significantly more pulpal inflammation compared with the other groups (p= 0.001). There were no significant differences among CEM cement, MTA and Biodentine in terms of the dentine bridge formation. The thickness of the dentin bridge formed in the Biodentine group was significantly higher than MTA and control group (p= 0.035 and p= 0.011, respectively). CONCLUSION: Although the dentin bridge formation and the thickness of dentin bridge formed in the Biodentine group were higher than the other groups, pulp showed greater inflammation compared to CEM cement and MTA. The results of this study suggested that MTA and CEM cement performed better when employed as the direct pulp capping material.

Prevention of secondary caries by a new antibacterial compound.

BACKGROUND: Since secondary caries is one of the main problems of dental composites. The creation of an antibacterial property in these composites is essential. The objective of this study was to synthesize 3-(2, 5-dimethylfuran-3-yl)-1H-pyrazole-5(4H)-one and check its biocompatibility and antibacterial properties in flowable dental composites. MATERIALS AND METHODS: In this animal study, the antibacterial activity of flowable resin composites containing 0-5 wt% 3-(2,5-dimethylfuran-3-yl)-1H-pyrazole-5(4H)-one was investigated by using agar diffusion and direct contact tests on the cured resins. Statistical analysis was performed using one-way ANOVA test (P < 0.001). Thirty male albino Wistar rats were used, weighing 200-250 g. Animals were randomly divided into three groups of ten; each animal received three implants, 3-(2, 5-dimethylfuran-3-yl)-1H-pyrazole-5(4H)-one, penicillin V, and an empty polyethylene tube. A pathologist, without knowing the type of material tested and the timing of the test, examined the samples. Statistical analysis was performed using Kruskal-Wallis test (P < 0.001). RESULTS: According to our findings, although the agar diffusion test reveals no significant difference between the groups, the direct contact test demonstrates that, by increasing the 3-(2,5-dimethylfuran-3-yl)-1H-pyrazole-5(4H)-one content, the bacterial growth was significantly diminished and the 3-(2,5-dimethylfuran-3-yl)-1H-pyrazole-5(4H)-one has a good biocompatibility (P < 0.05). CONCLUSION: Incorporation of 3-(2,5-dimethylfuran-3-yl)-IH-pyrazole-5(4H)-one into flowable resin composites can be useful to prevent Streptococcus mutans activity.

Comparative study of different cytotoxicity of bonding systems with different dentin thickness on L929 cell line: An experimental study.

BACKGROUND: Dentin-bonding agents should have good biocompatibility as they come into close and prolonged contact with vital dentin. The present study aimed to evaluate and compare the cytotoxicity of total etch and self-etch dentin bonding systems with two different dentin thickness on L929 cell line. MATERIALS AND METHODS: In this in vitro study 80 Class I cavities were prepared on the occlusal surfaces. The teeth were randomly divided to two groups of 40 each based on two RDT 0.5 mm and 1.5 mm. Samples were further subdivided into four subgroups of 10. Group 1: Adper Scotch bond Multi-Purpose (SBMP), Group 2: Adper Single Bond Plus (SBP), Group 3: Adper Scotch bond SE (SSE) and Group 4: Adper Easy One (EO). Group 1 and 2 were total-etch and Group 3 and 4 were self-etch. The cavities were sealed after applying of dentin bonding. Then crowns were immersed in culture medium for 24 hours and the cytotoxicity of resultant toxic extraction was measured with 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in 4 serial dilutions (neat,1/2 ,1/10 ,1/100). Data were analyzed by Two-way ANOVA and t-test. RESULTS: For all the dilutions, cytotoxicity was significantly higher with 0.5 mm remaining dentin thickness (RDT) relative to 1.5 mm RDT (P ≤ 0.05). In neat dilution for both RDTs, cytotoxicity was different among all the four dentin bondings. Expression in decreasing order of cytotoxicity was SBP > SBMP > SSE > EO for both RDTs in neat dilution (P < 0.05). For all the dilutions, cytotoxicity was significantly lower for self-etch bonding systems in comparison with total-etch bonding systems (P < 0.05). CONCLUSION: In the present study, lower cytotoxicity was found with an increase in the dilution of toxic extract and also cytotoxicity decreased with an increased dentin thickness. The adhesive systems had degrees of cytotoxic effects on cultured L929 compared to the control, except for the EO group.

Antibacterial, physical and mechanical properties of bonding agent containing synthesized Zinc Dimethacrylate.

BACKGROUND: The aim of this study includes synthesis of zinc dimethacrylate ionomer (ZDMA) by a new method, incorporate it into resin bonding and evaluate its antibacterial, physical and mechanical properties. MATERIAL AND METHODS: Resin adhesives containing 0 to 5% wt of ZDMA was produced and the following tests were accomplished: A: Antibacterial test: 1.Direct contact test. 2.Material aging; in both of them the bacterial colony counting were performed. B: Physical test: 1.Degree of conversion (D.C). 2.Evaluating the amount of released Zinc ion release in aqueous medium. C: Mechanical test: 1.Compressive strength test. 2.Shear bond test (enamel and dentine separately). The obtained results were statistically analyzed using One Way ANOVA and LSD post hoc test (α=0.05). RESULTS: The anti-bacterial test revealed that all the ZDMA containing groups significantly reduced the amount of Streptococcus Mutans bacteria. Moreover, the D.C in all ZDMA groups was enhanced. Furthermore, ion release analysis revealed noticeable stability of Zn2+ in samples, as in the 5wt.% group it was even after nine cycle of 24h wash. On the other hand, the compressive strength was significantly reduced just in the 5% ZDMA group while the other groups were superior comparing to the control. In addition, there was no significant difference among the enamel shear bond strength of the groups. However, about the dentine shear bond strength, only the 5% ZDMA group was significantly higher than the control. CONCLUSIONS: Low percentages of ZDMA in adhesive could impart anti-bacterial efficacy without challenging its mechanical and physical properties. Key words:Dental Resin Bonding, Zinc, Streptococcus mutans, Degree of conversion, Compressive strength.

Thermal Scanning of Dental Pulp Chamber by Thermocouple System and Infrared Camera during Photo Curing of Resin Composites.

INTRODUCTION: Due to thermal hazard during composite restorations, this study was designed to scan the pulp temperature by thermocouple and infrared camera during photo polymerizing different composites. METHODS AND MATERIALS: A mesio-occlso-distal (MOD) cavity was prepared in an extracted tooth and the K-type thermocouple was fixed in its pulp chamber. Subsequently, 1 mm increment of each composites were inserted (four composite types were incorporated) and photo polymerized employing either LED or QTH systems for 60 sec while the temperature was recorded with 10 sec intervals. Ultimately, the same tooth was hemisected bucco-lingually and the amalgam was removed. The same composite curing procedure was repeated while the thermogram was recorded using an infrared camera. Thereafter, the data was analyzed by repeated measured ANOVA followed by Tukey's HSD Post Hoc test for multiple comparisons (α=0.05). RESULTS: The pulp temperature was significantly increased (repeated measures) during photo polymerization (P=0.000) while there was no significant difference among the results recorded by thermocouple comparing to infrared camera (P>0.05). Moreover, different composite materials and LCUs lead to similar outcomes (P>0.05). CONCLUSION: Although various composites have significant different chemical compositions, they lead to similar pulp thermal changes. Moreover, both the infrared camera and the thermocouple would record parallel results of dental pulp temperature.

Telescopic Dental Needles versus Conventional Dental Needles: Comparison of Pain and Anxiety in Adult Dental Patients of Kerman University of Medical Sciences-A Randomized Clinical Trial.

INTRODUCTION: Pain felt during dental injections is dependent on dental anxiety. Patients feel increased pain if anxiety in the treatment environment is high, and therefore it is important to reduce anxiety during treatment to reduce pain. The purpose of this study was to compare pain and anxiety levels experienced during injections using a newly invented telescopic-coated dental needle that covers the conventional needle and also has the capability of applying topical anesthesia through its unique design with the conventional dental injection needle. METHODS: Dental injection anxiety questionnaires were completed by 60 adult patients who were randomly assigned to either the telescopic (a newly invented telescopic-coated dental needle that covers the needles) or the conventional group. Patients also completed visual analog scales to rate their pain perception during injection, their overall experience, and their future anticipated anxiety. Wilcoxon, Mann-Whitney, and Student t tests were used for statistical analysis. Statistical significance was defined as P < .05. RESULTS: A total of 25 men and 35 women with an age range of 19-55 years (mean age of 38.7 ± 2.31 years) participated in this study. Pain levels reported during the injection using the telescopic-coated needle (4.13 ± 1.37) were significantly lower than those using the conventional needle (5.63 ± 1.57), with statistically significant differences between the 2 groups (P < .05). Patients experienced significantly lower overall postinjection anxiety (P < .05) and had more positive overall experience ratings with the telescopic-coated needles. CONCLUSIONS: A new telescopic-coated dental needle was superior to a conventional injection system in pain perception and in reducing postinjection dental anxiety.

Prevalence of Upper Extremity Musculoskeletal Disorders in Dentists: Symptoms and Risk Factors.

AIM: The purpose of the present research was to examine the factors that lead to musculoskeletal disorders in dentists by assessing their posture using RULA method. MATERIALS AND METHODS: In this cross-sectional study, 130 dentists (84 male and 46 female) participated. The posture of the subjects during their normal workload was recorded by using the RULA method, and the range of musculoskeletal pains by using the Nordic Musculoskeletal Questionnaire (NMQ), and individual and professional data was assessed by a demographics questionnaire. All tests were performed at the P < 0.05 level. RESULTS: Assessment of the physical status of the subjects showed that 82.8% of subjects were at high risk of musculoskeletal disorders. The majority of musculoskeletal pains were in the neck (55.9%) and the shoulder (43.8%). Moreover, 68.9% of the subjects had experienced pain at least once over the last year. Significant relationships were observed between musculoskeletal pain and daily work hours (P = 0.07) and number of patients (P = 0.02), but the pain was not significantly associated with BMI and experience. CONCLUSION: The present findings showed that unsuitable posture of dentists during work has a considerable effect on musculoskeletal disorders. Therefore, further investigation is required to avoid the detrimental effects of wrong posture.

Histological assessment of pulpal responses to resin modified glass ionomer cements in human teeth.

BACKGROUND: The biocompatibility of resin-modified glass ionomers (RMGIs) as a lining material is still under question. The present study evaluated the response of the pulp-dentin complex following application of resin-modified glass-ionomer cement, calcium hydroxide and conventional glass-ionomer in deep cavities prepared in human teeth. MATERIALS AND METHODS: In this controlled clinical trial, 30 deep class V buccal cavities (3 mm × 2 mm × 2 mm) were prepared in human premolars treatment planned to be extracted for orthodontic reasons and divided into 3 groups. Groups were lined by a RMGI (Vivaglass), conventional glass Ionomer (Ionocid) and calcium hydroxide respectively. The cavities were subsequently filled with amalgam. Each group was then divided into two sub-groups according to time intervals 5 and 30 days. The patients were referred to Kerman Dental School and in accordance with orthodontic treatment plan; premolars were extracted and then prepared for histological assessment. The sections were stained with hematoxylin and eosin and periodic acid Schiff techniques. All of the samples were examined using a number of criteria including odontoblastic changes, inflammatory cells response, reactionary dentin formation and presence of microorganisms. The data were analyzed by Kruskal-Wallis and Mann-Whitney tests. P < 0.05 was considered as significant. RESULTS: There was no significant difference among odontoblastic changes, reactionary dentin, presence of bacteria and inflammatory cells response of the groups (P > 0.05). CONCLUSION: Ionocid and Vivaglass resin-modified glass ionomers can be used as lining materials in human teeth.

A comparative study on dental pulp response to calcium hydroxide, white and grey mineral trioxide aggregate as pulp capping agents.

CONTEXT: Vital pulp therapy has been known as one of the treatment options to preserve pulp after being exposed by trauma or caries. AIM: To investigate human pulpal response to white and grey mineral trioxide aggregate (WMTA, GMTA) and Dycal (MTA) as pulp capping agents. SETTING AND DESIGN: Human volunteers were participated in this randomized clinical trial. MATERIALS AND METHODS: This study was conducted on 90 intact first and second premolars of human maxillary and mandibular teeth. The teeth were randomly assigned into three groups of 30 each. Under local anesthesia, teeth were exposed and capped either with GMTA, WMTA, or Dycal. After 30, 60, and 90 days 10 teeth of each group were extracted and prepared for histologic observation. STATISTICAL ANALYSIS: Histopathologic data were analyzed by χ(2), Kruskal Wallis and Mann Whitney tests. RESULTS: the calcified bridge in teeth that were capped with GMTA was significantly thicker than Dycal at 30 and 60 days (P= 0.015 and P=0.002, respectively); whereas WMTA showed significantly thicker calcified bridge than Dycal at 90 days (P=0.02). In addition, GMTA specimens showed significantly less inflammation compared to Dycal samples at 90 days interval (P=0.019). No significant difference was found between GMTA and WMTA in terms of calcified bridge thickness and pulp inflammatory response to the capping materials (P>0.05). CONCLUSIONS: Based on the result of this study, both types of MTA can be suggested as the materials of choice for direct pulp capping procedure instead of Dycal as hard setting calcium hydroxide cement.

Maturogenesis of a complicated crown fracture: a case report with 8 years follow-up.

This report describes a case of a 7 years old girl who suffered from complicated crown fracture of right mandibular central incisor because of a bicycle accident. For the tooth partial pulpotomy with calcium hydroxide, capping was performed in order to achieve apexogenesis and the tooth was restored with a double-seal of glass ionomer cement and composite resin. The patient was reviewed over 8 years. The tooth showed continued root development and complete apex formation.

SEM evaluation of neodentinal bridging after direct pulp protection with mineral trioxide aggregate.

The purpose of this study was to observe the basic morphology and determine the chemical composition of neodentinal bridges adjacent white mineral trioxide aggregate (WMTA) when used as a direct pulp capping material. The experimental procedures were performed on six intact dogs' teeth. The pulps were exposed and cavities were filled with WMTA. After 2 weeks, neodentinal bridge formation was evaluated by scanning electron microscope (SEM) of cross-sections of the specimens and electron probe microanalysis (EPMA) of the pulpal surfaces. Results of SEM observation showed that the most characteristic reaction of pulp cells was the intimate connection of cell processes and secreted extracellular fibres with the crystals of the pulp capping material. Results of EPMA indicated that the mineralisation of neodentinal bridge formation occurred progressively from the periphery to the central area. Based on these results, it appears that WMTA has the potential to be used as a direct pulp capping material during vital pulp therapy.