Comparison of the elastic recovery and strain-in-compression of commercial and novel vinyl polysiloxane impression materials incorporating a novel crosslinking agent and a surfactant.

This study aims to formulate experimental vinylpolysiloxane (VPS) impression materials and compare their elastic recovery and strain-in-compressions with three commercial VPS materials (Aquasil, Elite, and Extrude). Five experimental materials (Exp), two hydrophobic (Exp-I and II) and three hydrophilic (Exp-III, IV and V) were developed. Exp 1 contained vinyl-terminated poly-dimethyl siloxane and a conventional cross-linking agent (poly methylhydrosiloxane), while Exp- II contained a novel cross-linking agent that is tetra-functional dimethyl-silyl-ortho-silicate (TFDMSOS). Exp III-V (hydrophilic materials) were formulated by incorporating different concentrations of non-ionic surfactant (Rhodasurf CET-2) into Exp II formulation. Measurement of elastic recovery and strain-in-compression for commercial and experimental materials were performed according to ISO4823 standard using the calibrated mechanical testing machine (Tinius Olsen). One-way analysis of variance (one-way ANOVA) and Tukey's post-hoc (HSD) test were used for statistical analysis and a p-value of ≤ 0.05 was considered significant. Exp-I has statistically similar values to commercial VPS. The Exp-II showed the highest elastic recovery, while % elastic recovery was reduced with the addition of the non-ionic surfactant (Rhodasurf CET-2). The % reduction was directly related to the concentration of Rhodasurf CET-2. In addition, Exp II had significantly higher strain-in-compression values compared to Exp-I and commercial materials. These values were further increased with the addition of a non-ionic surfactant (Rhodasurf CET-2) was added (Exp-III, IV and V).

Surface Microhardness Of Microhybrid And Nanocomposite After Storage In Mouth Washes.

BACKGROUND: Dental composites are aesthetic direct restorative material. However, the effect of mouthwashes on the durability of the material is controversial. This study evaluated and compared the influence of mouthwash composition on the surface hardness of nanofilled (Z350XT) and microhybrid (P60) resin composites. METHODS: Comparative in-vitro study was conducted over 6 months at Multan Medical & Dental College. Sixty-four disc-shape specimens of each {nanofilled (Z350XT) and microhybrid (P60)} resin composite were prepared and stored in distilled water at 37°C for 24 hours. The baseline microhardness reading (To) was recorded by Vickers micro-hardness tester. Samples were then randomly divided into four groups (n=16) and stored in Listerine Cool Mint, Colgate Plax, Clinica and distilled water (control). The hardness test was repeated after 12 hours and 24 hours of storage. RESULTS: Nanocomposite (Z350XT) had statistically (p<0.01) higher surface hardness. A significant reduction (p≤0.05) in microhardness was observed after immersion of samples in mouthwashes. The reduction in surface hardness was dependent on the immersion time and composition of mouthwashes. Listerine Cool Mint (alcohol-based mouthwash) had greatest degradation effect. CONCLUSIONS: Mouth rinses negatively impacted the surface microhardness of the tested resin-based materials. Alcohol-based mouthwashes had greater potential for reducing microhardness. Microhybrid composite appears to be a more suitable material for restoring teeth in patients accustomed to using regular mouthwashes.

Synthesis, characterization, and evaluation of the antifungal properties of tissue conditioner incorporated with essential oils-loaded chitosan nanoparticles.

PURPOSE: This study aims to investigate new tissue conditioner (TC) formulations involving chitosan nanoparticles (CSNPs) and essential oils (EO) for their antifungal potential, release kinetics, and hardness. MATERIALS AND METHODS: CSNPs were synthesized, and the separate solutions of CSNP were prepared with two types of EO, i.e., Oregano oil and Lemongrass. The EO was loaded separately in two concentrations (200 µL and 250 µL). The blank and EO-loaded CSNPs were screened against Candida albicans (C. albicans), and their minimum inhibitory concentration was established. GC Reline™ (GC corporation, USA) TC was considered a control group, whereby the four experimental groups were prepared by mixing CSNPs/EO solutions with TC powder. The antifungal effectiveness (C. albicans) and release kinetics behavior (1-6 h, 24 h, 48 h, and 72 h) was investigated. The Shore A hardness of control and experimental groups was evaluated in dry and wet modes (deionized water and artificial saliva). For statistical analysis, SPSS version 22 was used to do a one-way ANOVA post-hoc Tukey's test. RESULTS: Compared to the control group, TCs containing blank CSNPs and CSNPs loaded with EO showed 3 and 5 log reductions in C. albicans growth, respectively. A significantly high antifungal effect was observed with TC containing lemongrass essential oil (200 µL). The continuous release of EO was detected for the first 6 hours, whereas completely stopped after 48 hours. Mean hardness values were highest for dry samples and lowest for samples stored in artificial saliva. The statistically significant difference within and between the study groups was observed in mean and cumulative essential oils release and hardness values of TCs over observed time intervals irrespective of storage media. CONCLUSION: TCs containing essential-oil-loaded CSNPs seem a promising alternative treatment of denture-induced stomatitis, however, a further biological analysis should be taken.

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.

Dimensional changes of commercial and novel polyvinyl siloxane impression materials following sodium hypochlorite disinfection.

BACKGROUND: Dental impressions are used to record anatomy of teeth and surrounding oral structures. Impression materials become contaminated with saliva and blood requiring disinfection, which may have negative impact on dimensional stability of materials. OBJECTIVE: Comparatively evaluate linear dimensional changes of synthesized Tetra-functional (dimethylsilyl) orthosilicate (TFDMOS) containing Polyvinylsiloxane (PVS) impressions following sodium hypochlorite disinfection. METHODS: Percentage dimensional changes of three commercial PVS (Elite HD Monophase, Extrude and Aquasil Ultra Monophase) and five experimental PVS impression materials were measured. Experimental material contained novel cross-linking agent (TFDMOS) and a non-ionic surfactant (Rhodasurf CET-2) that is Exp-A (without TFDMOS), Exp-B (with TFDMOS), Exp-C (TFDMOS+ 2% Rhodasurf CET-2), Exp-D (TFDMOS+ 2.5% Rhodasurf CET-2) Exp-E (TFDMOS+ 3% Rhodasurf CET-2). Samples were made using rectangular stainless-steel molds (40 × 10 × 3 mm3) and linear dimensional changes were measured using a calibrated travelling microscope at 10× magnification after immersion in distilled water (D.W) and 1% Sodium Hypochlorite solution at two different time intervals i.e., 30 min and 24 h. RESULTS: Samples immersed in 1% NaOCl showed significant (p < 0.05) dimensional changes after 30 min of immersion. Exp-E showed significantly greater dimensional changes than their control (Exp-A and Exp-B). In distilled water, there were no significant difference among the tested materials. Aquasil exhibited highest expansion (0.06%) in both solutions. At 24 h, among the commercial materials, Extrude had the greatest expansion followed by Aquasil and Elite in DW while Aquasil showed the greatest expansion followed by Extrude and Elite in NaOCl. CONCLUSION: Experimental PVS had linear dimensional changes within the ISO 4823; 2015 recommended range. However, extended immersion can negatively affect the linear dimensions.

Determination of Shear Bond Strength of Nanocomposite to Porcelain and Metal Alloy

Abstract Objective: To compare porcelain and metal repair done with both nanocomposite and conventional composite. Material and Methods: A total of 30 cylinders were fabricated from Porcelain (I), Porcelain fused to metal (II), and metal (III) substrate each. Control group (A) was bonded with conventional micro-hybrid composite and experimental group (B) was bonded with nanocomposite in a 2 mm thickness. All specimens were thermocycled and stored in distilled water at 37 °C for 7 days. A universal testing machine was used to measure the Shear bond strength (SBS). The difference between bond strengths of the groups was compared using an independent t-test. Results: In all three groups, the SBS was higher in the experimental group as compared to the control group. The use of nanocomposite of metal alloy presented maximum shear bond strength, followed by samples of porcelain fused to metal and finally porcelain, showing the lowest values of SBS. Conclusion: Porcelain and alloys bonded with nanocomposite exhibit enhanced adhesiveness as well as aesthetic and mechanical properties. This subsequently would translate into providing higher clinical serviceability and durability and hence a cost-effective and accessible repair option for human welfare (AU).

Patient's perspective and awareness of materials used in dentistry.

OBJECTIVE: To assess patients' knowledge and attitude towards different dental materials used in private and public dental facilities in an urban setting. METHODS: The cross-sectional study was conducted at the Islamabad Dental and Medical College, Islamabad, Pakistan, from February to July 2019, and comprised individuals at private dental clinics and teaching hospitals. Data was collected using a pre-validated structured questionnaire that recorded socio-demographic information as well as patients' perception on evidence-based dentistry using visual analogue, trust on the dentist, quality of materials and the source of information. Data was analysed using SPSS 21. RESULTS: Of the 269 participants, 151(56.1%) were females with a mean age of 33.87±12.63 years, and 118(43.9%) were males with a mean age of 33.28±13.71 years. Overall, 208(77.3%) respondents were in favour of using materials with long-term scientific data; 201(74.7%) recognised a difference in quality of materials used at private clinics and teaching hospitals; 128(63.7%) believed that poor quality materials were used in teaching hospitals; 229(85%) trusted their dentists for using high-quality materials; and 108(40%) identified dentists as the source of information. There was a significant relationship between patient's education level and realising the importance of using dental materials supported by scientific evidence (p≤0.01). CONCLUSIONS: Majority of subjects believed that poor quality materials were used in teaching hospitals compared to private dental facilities.

Oral assessment of children with autism spectrum disorder in Rawalpindi, Pakistan.

Comparison of oral health status, dental needs and dietary habits of children with autism and their healthy siblings. In this cross-sectional study, oral hygiene measures, sugar consumption and dental examination of 58 Pakistani children with autism spectrum disorder were assessed and compared to 27 of their siblings without autism spectrum disorder. Questionnaires were distributed to their parents regarding oral hygiene measures, dietary habits and past dental experiences. Clinical examination for the presence of dental caries, periodontal disease or parafunctional habits was carried out and findings were associated with the mother's education. Children with autism had a higher incidence of caries (50%) as compared to their healthy siblings (22.2%). Significant differences were observed between the groups regarding frequency of brushing and independent brushing. Dental plaque was observed on anterior teeth in 24% children with autism spectrum disorder as compared to 14% in the control group. Trauma due to self-injurious behaviour and bruxism was also recorded and compliance during clinical examination was noted in children with autism spectrum disorder. There was no significant difference in sugar consumption between children with autism spectrum disorder and their healthy siblings. Children with autism had greater dental needs and were more prone to developing dental problems as compared to their healthy siblings.

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.