Physico-Mechanical Properties of Commercially Available Tissue Conditioner Modified with Synthesized Chitosan Oligosaccharide.

This study aims to compare the hardness, sorption and solubility of commercially available tissue conditioner [TC] modified with chitosan [CS] and synthesized chitosan oligosaccharide [COS] in antifungal concentration. COS was synthesized by acid hydrolysis and characterized by FTIR and XRD. Experimental materials were formulated by incorporating each per gram of TC powder with effective antifungal concentration of chitosan 1.02 mg (Group 1: TC-CS) and 0.51 mg COS (Group 2: TC-COS). A commercially available TC was used as control (Group 0: CTC). Shore A hardness test was performed according to ASTM D 2240-05 (2010) standards on samples stored in dry environment, distilled water (DW) and artificial saliva (AS) at 37 °C (n = 5 per group). Percent weight changes (n = 5 per group) after storage in DW and AS was used to record sorption and solubility. One-way Anova with post hoc Tukey's test was applied. FTIR and XRD confirmed low molecular weight and amorphous nature of COS. Experimental groups had higher Shore A hardness values; however, these changes were not significant. Greatest variations in durometer values (p ≤ 0.05) were observed during the first 24 h. Experimental groups had higher (p ≤ 0.05) percentage sorption and solubility. Samples stored in DW had significantly higher (p = 0.019) sorption, whereas material had higher (p = 0.005) solubility in AS. Mean solubility values in both immersion mediums was highest for Group 2, followed by group 1 and group 0. In addition, significant (p ≤ 0.05) increase in solubility upon aging was noted for each material. Experimental tissue conditioner had higher hardness, sorption and solubility. However, these changes are not substantial to interfere with their tissue healing property. Therefore, these materials may be considered and explored further as potential antimicrobial drug delivery agent for denture stomatitis patients.

Low-temperature flow-synthesis-assisted urethane-grafted zinc oxide-based dental composites: physical, mechanical, and antibacterial responses.

A novel way was adopted to graft zinc oxide (ZnO) with urethane-modified dimethacrylate (UDMA) in order to utilize them as reinforcing agents in resin-based dental composites. Experimental novel composites were synthesized having UDMA-grafted and nongrafted ZnO, at a concentration of 0 wt.%, 5 wt.%, and 10 wt.%. The same concentrations of ZnO were also incorporated in Filtek Z250 XT (3 M ESPE, USA). The antibacterial behavior was evaluated against Streptococcus mutans by direct-contact test at one, three, and seven days of incubation. The compressive strength and Vickers microhardness were tested as per ISO 9917 and ISO/CD6507-1, respectively. For abrasive wear resistance, mass loss and roughness average after tooth-brushing cycles of 24,000 at custom-made tooth-brushing simulator were evaluated using noncontact profilometer. Data analysis was carried out using post hoc Tucky's test and nonparametric Kruskal-Wallis test. Direct contact test revealed that the antibacterial potential of novel and commercial composites was increased with an increase in the concentration of grafted ZnO as compared with nongrafted, whereby the potential was the highest at day seven. There was a significant decrease in compressive strength and Vickers hardness of commercial composites on addition of grafted ZnO while there was no significant difference in the strength of experimental novel composite. The abrasive wear of commercial and experimental composites was within clinical limits. Low-temperature flow-synthesis method was successfully employed to synthesize grafted and nongrafted ZnO. The UDMA-grafted ZnO can be incorporated into dental composites without decreasing their strength and these composites can be used to combat secondary caries.

Effectiveness of Thymoquinone and Fluoridated Bioactive Glass/Nano-Oxide Contained Dentifrices on Abrasion and Dentine Tubules Occlusion: An Ex Vivo Study.

OBJECTIVES: Dentin hypersensitivity (DH) is mainly due to the loss and replenishment of minerals from tooth structure, where the lost minerals can be rehabilitated with a biomimetic approach. The objectives were to determine the relative dentin abrasivity (RDA) of experimental (EXT) dentifrices and to determine the efficacy to occlude dentinal tubules. MATERIALS AND METHODS: Experimental dentifrices contained nano-fluoridated bioactive glass (n-FBG: 1.5 wt.% [EXT-A], 2.5 wt.% [EXT-B], and 3.5 wt.% [EXT-C]), nano-zinc oxide (n-ZnO), and thymoquinone as active agents. Bovine dentin blocks were subjected to brushing treatments as per groups, that is, distilled water; commercial dentifrice (control, CT); EXT toothpastes; and EXT-D without active agents. Samples were tested for three-dimensional (3D) abrasion analysis according to ISO-11609:2010 (International Organization for Standardization [ISO]). The roughness average (Ra), RDA, surface topography, and elemental compositions were investigated. STATISTICAL ANALYSIS: One-way analysis of variance (ANOVA) with post-hoc Tukey's and Tamhane's test was performed for characterizations using Statistical Package for the Social Sciences (SPSS) version 21. The result was considered significant with p-value ≤ 0.05. RESULTS: Comparisons of Ra differed significantly between all groups with p < 0.05 except CT and EXT-A. The RDA values of EXT-A, EXT-B, and EXT-C were calculated as 74.04, 84.26, and 116.24, respectively, which were well within the acceptable limit set by international standards. All n-FBG containing dentifrices demonstrated uniform occlusion of dentinal tubules; however, highly concentrated EXT dentifrices showed more occlusion. CONCLUSIONS: Acceptable range of RDA and superior occlusion of tubules by novel dentifrices suggest that it may be recommended for treating DH.

In-vitro antifungal efficacy of tissue conditioner-chitosan composites as potential treatment therapy for denture stomatitis.

Tissue conditioners are commonly used to improve the adaptation of ill-fitting dentures. These materials are easily colonized by Candida albicans (C. albicans), resulting in "denture stomatitis". Chitosan and its derivative possess inherent antifungal activity. This study aims to formulate a chitosan-based tissue conditioner and assess its anti-fungal efficacy against C. albicans over time. A chitosan oligosaccharide (COS) was synthesized from commercially purchased chitosan and was characterized by Fourier Transform Infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD). The minimum inhibitory concentration (MIC) of COS and commercial chitosan against C. abicans was evaluated using broth micro-dilution assay (n = 3). Next, it was incorporated into tissue conditioners and two experimental groups i.e. tissue conditioner modified by chitosan (TC-CH) and tissue conditioner modified by COS (TC-COS) were prepared. The in-vitro antifungal activity of experimental group was compared with a control group (chitosan-free tissue conditioner) by counting numbers of colony forming units (CFUs) (n = 3). The antifungal potential of experimental formulations over time in a simulated oral environment was also evaluated using a spectrophotometry (n = 3). A potent in-vitro antifungal activity against C. albicans was observed. The minimum inhibitory concentration (MIC) of pure commercial chitosan and COS was 0.625 mg/ml and 0.3125 mg/ml respectively. Compared to the control group, experimental groups showed a reduction in number of CFUs of C. albicans density. Once immersed in saliva, the TC-CH retained its inhibitory effect for 24 h, while TC-COS exhibited improved inhibition until the third day, beyond which a gradual reduction in the inhibitory effect was observed. Experimental formulations showed a reduction in C. albicans density compared to the control group. Thus, a novel combination of chitosan and tissue conditioners is a promising alternative for prevention and treatment of denture stomatitis.

Comparison Of Two Intracanal Medicaments In Resolution Of Apical Radiolucency.

BACKGROUND: As a gold standard, calcium hydroxide has always been used as a root canal medicament against root canal pathogens but its combination with chlorhexidine is not being employed in routine despite its documented efficacy and results. The objective of the study is to compare calcium hydroxide and combination of calcium hydroxide with 2% CHX on the basis of radiographic evidence of resolution of periapical radiolucency when they are used as an interappointment dressing /intracanal medicament for 14 days.. METHODS: A total of 60 patients of either gender was included in the study. The age range was 15-60 years with the radiographic evidence of radiolucency of 2-4 mm in size. Both maxillary and mandibular teeth till first molar were selected. Teeth with previous endodontic treatment mentally handicapped and terminally ill patients were excluded. Selected patients were placed randomly into Group 1 (calcium hydroxide alone) and in Group 2 (calcium hydroxide in combination with 2% chlorhexidine gel). Obturation and permanent filling was done at 14th day. The patient was recalled after 90 days of obturation and a radiograph was taken. Final outcome was measured at the end of 90thday of obturation. RESULTS: The mean of percentage reduction in size of apical radiolucency at 3 months was 91.03% for group 1 and 97.26% for group 2 with p-value 0.13 (not significant). The results suggested equivalent results after medication with 2%chlorhexidine with calcium hydroxide but 2% chlorhexidine still showed better results than the group without CHX in terms of healing. CONCLUSIONS: This study concluded that calcium hydroxide in combination with 2% chlorhexidene as intracanal medicament results in better resolution of periapical radiolucency in terms of percentage resolution of periapical radiolucency.

Comparison of frequency of post-obturation pain of single versus multiple visit root canal treatment of necrotic teeth with infected root canals. A Randomized Controlled Trial.

OBJECTIVE: To determine the pain of single versus multiple visit endodontic treatment after obturation in teeth with necrotic pulps and infected canals. METHODS: The randomized controlled study was conducted from January to June 2016 at Shaheed Zulfiqar Ali Bhutto Medical University, Islamabad, Pakistan. Dental patients aged 18-60 years of either gender were selected who were subjected to computer-generated randomisation. Both maxillary and mandibular single rooted teeth till second premolar were included. Single visit endodontic treatment to Group-I subjects was carried out by gaining access to canals, cleaning, shaping and obturation at same visit whereas in Group-II patients, who underwent multiple visits, cleaning and shaping was followed by placement of intra-canal medicament, while obturation was done 5 days later. Patients were recalled within 48 hours after obturation to record the pain score using visual analogue scale.. RESULTS: Of the 60 patients, 30(50%) were in each of the two groups. There was no significant difference in post-operative pain in the two groups (p=0.8). The frequency of post-operative pain was not significant either (p>0.05). The post-operative mean pain score was 2.23±1.736 in Group-I and 2.38±1.94 in Group-II (p=0.8).. CONCLUSIONS: Treatment carried out in single visit or multiple visits showed no difference in pain frequency.

Microwave-assisted synthesis and in vitro osteogenic analysis of novel bioactive glass fibers for biomedical and dental applications.

Glass fiber-based materials have gained interest for use in biomedical and dental applications. The aim of this study was to make E-glass fiber bioactive by a novel method using the microwave irradiation technique. Industrial E-glass fibers were used after surface activation with the hydrolysis method. The ratio of calcium and phosphorous precursors was set at 1.67. After maintaining the pH of the calcium solution, E-glass fibers in two ratios, i.e. 30% (nHA/E30) and 50% (nHA/E50) wt/wt, were added. The phosphorous precursor was added later and the solution was irradiated in a microwave to obtain nano-hydroxyapatite (nHA) particles on E-glass fibers. The structural, physical and in vitro biocompatibility analyses of the resulting materials were conducted. The expression of osteopontin (OPN) and collagen (Col) type 1 was measured by reverse transcription polymerase chain reaction (RT-PCR) and comparison was made between all the groups. Fourier transform infrared spectroscopy and x-ray diffraction showed characteristic peaks of nHA, and a change in the peak intensities was observed with an increase in the concentration of E-glass fibers. Scanning electron microscopic (SEM) images confirmed the homogenous adhesion of nHA spherical particles all over the fibers. Cell viability with mesenchymal stem cells showed growth, proliferation, and adhesion. All the materials were able to upregulate the expression of the OPN and Col, where gene expression was highest in nHA followed by nHA/E30 and nHA/E50. The bioactive glass fibers were synthesized in the shortest time and showed osteogenic properties. These materials have the potential for use in bone tissue engineering, dental prosthesis, and tooth restoration.

Comparative abrasive wear resistance and surface analysis of dental resin-based materials.

OBJECTIVE: The objective of this study was to assess the surface properties (microhardness and wear resistance) of various composites and compomer materials. In addition, the methodologies used for assessing wear resistance were compared. MATERIALS AND METHODS: This study was conducted using restorative material (Filtek Z250, Filtek Z350, QuiXfil, SureFil SDR, and Dyract XP) to assess wear resistance. A custom-made toothbrush simulator was employed for wear testing. Before and after wear resistance, structural, surface, and physical properties were assessed using various techniques. RESULTS: Structural changes and mass loss were observed after treatment, whereas no significant difference in terms of microhardness was observed. The correlation between atomic force microscopy (AFM) and profilometer and between wear resistance and filler volume was highly significant. The correlation between wear resistance and microhardness were insignificant. CONCLUSIONS: The AFM presented higher precision compared to optical profilometers at a nanoscale level, but both methods can be used in tandem for a more detailed and precise roughness analysis.