Influence of mouth rinses on the surface hardness of dental resin nano-composite

In Vitro Effect of Mouthrinses on the Microhardness of Three Different Nanohybrid Composite Resins

Introduction

Daily use of different mouthrinses at home or in the dental office can alter the properties of resin hardness. The present study aimed to compare Vickers microhardness (VHN) in vitro of nanohybrid composite resins (NCRs) immersed in mouthrinses.

Materials and Methods

In total, 120 discs (10 ⨯ 2 mm) were prepared from three NCR shade A2 (n = 40/group) with FiltekTM Z350 XT (Z350XT), Tetric EvoCeram (TEC), and Polofil NHT (PNHT). The specimens were incubated in artificial saliva (37°C ⨯ 24 hr). Specimens were distributed into four mouthrinses (n = 10/group) of artificial saliva (control), chlorhexidine (CHX 0.12%, pH 5.6), cetylpyridine chloride (CPC 0.075%, pH 5.84), and CHX 0.12% + CPC 0.05% (pH 6.2) (2 times/day, 2' ⨯ 12 hr). The VHN (300 gf/10") was measured after 24 hr, 14, and 21 days. Data were analyzed by three-way analysis of variance, followed by post hoc Tukey analysis at 0.05 level of significance.

Results

The results revealed a global effect of the interaction of the mouthrinses ⨯ time between NRC evaluated (P=0.001). Baseline VHN in PNHT and Z350XT was higher than TEC. Within each group of NCR, VHN of CHX + CPC > other mouthrinses (PNHT/14 days; Z350XT/21 days), and >CPC (Z350XT/14 days). In mouthrinses-intragroups, VHN of PNHT and Z350XT decreased at 14 days (CHX, CPC) and was maintained over time in NCR (CHX + CPC). VHN-TEC was similar among groups.

Conclusion

Microhardness showed differences due to the interaction of the type of NCR, the composition of the mouthrinses, and time. VHN decreased after 14 days and was more affected in composite resins with lower filler content and in mouthrinses with a lower pH.

Surface, mechanical and chemical properties of modified denture resin using natural biopolymer

Objective

This laboratory study determined the surface, mechanical and chemical properties of polymethyl methacrylate (PMMA) denture resin reinforced with micron-sized Gum Arabic (GA) powder in different weight ratios.

Methods

This laboratory study was conducted at the Dental Health Department of the College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia from November 2022 to February 2023. Three experimental denture resins were prepared by incorporating GA powder in heat-polymerized PMMA powder using different wt.% (5, 10, and 20 wt.%). While pristine PMMA served as the control group. A total of ten bar-shaped specimens with dimensions of 65 mm × 10 mm × 3.5 mm were prepared for each study group. The surface properties (micro CT and SEM evaluation), mechanical properties (Nanohardness, elastic modulus and flexural strength) and chemical properties (FTIR) were conducted. The data were statistically analyzed using the one-way analysis of variance and Tukey's post hoc tests (p<0.05).

Results

The surface and bulk properties of experimental GA-reinforced PMMA resin materials deteriorated while the mechanical properties were also negatively altered using GA-based PMMA denture resin. A linear correlation was observed between weak mechanical properties and increasing wt.% of GA in denture resin.

Conclusions

The incorporation of GA powder in denture resin might not be a viable option. The surface and mechanical properties of experimental PMMA composites were adversely affected compared to the control group.

Fiber-reinforced composites in dentistry - An insight into adhesion aspects of the material and the restored tooth construct

OBJECTIVE

This review aimed to highlight the insight into adhesion aspects within the components of the glass FRC (i.e., fiber and matrix) and between resin luting material and the glass FRC construction.

METHODS

The fundamentals of semi-interpenetrating polymer network (semi-IPN) based FRCs and their advantages in forming a solid adhesive interface with indirect FRC restoration, dental adhesive, and luting cement are elaborated. The important resin matrix systems and glass fibers used in FRCs are discussed. This is principally based on a survey of the literature over Medline/PubMed, Web of Science, and Scopus databases and a review of the relevant studies and publications in scientific papers in international peer-reviewed journals for the specific topic of biomaterials science. The keywords used for the search approach were: adhesion, fiber-reinforced composite, glass fiber, and semi-interpenetrating polymer network.

RESULTS

The polymer matrix systems of semi-IPN-based FRCs and formation of secondary-IPN layer are pivotal for bonding of multiphasic indirect dental constructs and repair. Additionally, describing areas of indication for FRCs in dentistry, explaining the adhesion aspects of FRC for the cohesion of the material itself, and for obtaining durable adhesion when the FRC construct is luted to tooth and remaining dentition. Current progress in the field of FRC research and future directions are summarized and presented.

SIGNIFICANCE

By understanding the isotropic-anisotropic nature of fibers and the interfacial adhesion within the components of the FRC; between resin cement and the FRC construction, the clinically successful FRC-based multiphasic indirect tooth construct can be achieved. The interfacial adhesion within the components of the FRC and between resin luting material and the FRC construction play a key role in adhesion-based unibody dental restorations.

Mechanical and Biomimetic Characteristics of Bulk-Fill Resin Dental Composites Following Exposure in a Simulated Acidic Oral Environment

During the last 10 years, various companies have marketed different "bulk-fill" resin dental composites for the restoration of posterior stress-bearing teeth; however, the impact of acidic conditions on these relatively newer materials has not been thoroughly investigated. Therefore, an attempt was made to evaluate the effect of acidic beverages on the mechanical biomimetic characteristics of four bulk-fill and one conventional nanohybrid resin-based dental composites (RBCs). The specimens of each RBC were stored in two acidic beverages namely 'Orange Juice' and 'Coca-Cola', whereas 'dry' and 'distilled water' storage of specimens served as controls. After 1 week of storage, flexural and surface hardness properties of specimens were determined using a universal testing machine and Vickers hardness tester, respectively. In general, the 'Coca-Cola' beverage caused the greatest degradation of flexural strength, flexural modulus, and surface hardness characteristics in all RBCs in contrast to the 'dry', 'distilled water' controls and 'Orange Juice' storage conditions. However, the overall mechanical biomimetic performance of nanohybrid RBCs was relatively better than all other bulk-fill RBCs and may, therefore, be considered a suitable candidate for the restoration of posterior stress-bearing permanent dentition.

Effect of Gum Arabic powder on the mechanical properties of denture base acrylic

Objective

This study aimed to improve the mechanical properties of denture base material using various concentrations of natural biopolymer, i.e., Gum Arabic (GA).

Methods

This experimental study was conducted at the Dental Health Department of the College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia from May 2022 to July 2022. After obtaining exemption from the institutional review board, the powdered GA was added in ratios of weight 5, 10, and 20% to PMMA heat-cured acrylic powder to produce bar-shaped samples (65 × 10 × 30 mm3 in dimensions). While the control group was prepared as such. Micro hardness (n=10/group) and fracture toughness (n=10/group) were evaluated. One-way analysis of variance method was used to statistically analyze the results (p<0.05) using SPSS version 23.

Results

Significant differences were observed for micro hardness (p<0.001) and fracture toughness (p=0.007) between the means of the different study groups. The control group exhibited the highest micro hardness (22.5±0.6 VHN) and fracture toughness (1.25±0.11 MPa.m1/2) value among the study groups. While 20 wt. % GA and 10 wt. % GA groups showed the lowest micro hardness and fracture toughness values, respectively.

Conclusions

GA powder might not be an appropriate reinforcing material for denture base or the higher filler loading of GA in denture base acrylic might be detrimental to the mechanical properties.

Symptom remission and functional outcome in an Egyptian sample of patients with schizophrenia

Background

The ultimate treatment goal of schizophrenia is regaining patients’ pre-morbid function.

Results

Ninety-three outpatients with schizophrenia, diagnosed according to the criteria of Diagnostic and Statistical Manual of Mental Disorders—fourth edition (DSM-IV), were recruited, of whom 35 patients (37.6%) had achieved the remission severity criteria, whereas 58 patients (62.4%) failed to fulfill the criteria for remission. The functional aspects were examined by the Global Assessment of Functioning scale (GAF) and the Social Functioning Questionnaire (SFQ). Predictors of outcome were examined by applying binary logistic regression analysis. Patients who fulfilled those specific criteria for remission showed a favorable outcome in the assessed areas, regarding GAF and social functioning in society. Lack of judgment or insight item of PANSS showed significantly good functional outcomes.

Conclusion

The results suggest that the remission concept has important implications for the treatment of schizophrenia. Remission seems to be associated with better functional capabilities. However, this does not necessarily mean that remitted patients have “adequate” functioning, especially regarding the social skills domain.

Readiness to deliver person-focused care in a fragile situation: the case of Mental Health Services in Lebanon

BACKGROUND

Evidence suggests wide variability in the provision of mental healthcare across countries. Countries experiencing fragility related risks suffer from a high burden of mental-ill health and additionally have limited capacity to scale up mental health services given financial and human resource shortages. Integration of mental health services into routine primary care is one potential strategy for enhancing service availability, however little is known about the experiences of currently active health care providers involved in mental health and psychosocial support service (MHPSS) provision at primary care level. This study aims to determine how healthcare providers offering MHPSS services at primary care levels in Lebanon perceive mental health and the health system's ability to address the rising mental ill-health burden with a view to identify opportunities for strengthening MHPSS service implementation geared towards integrated person focused care model.

METHODS

A qualitative study design was adopted including 15 semi-structured interviews and 2 participatory group model-building workshops with health care providers (HCPs) involved in mental healthcare delivery at primary care level. Participants were recruited from two contrasting fragility contexts (Beirut and Beqaa). During workshops, causal loop diagrams depicting shared understandings of factors leading to stress and mental ill health, associated health seeking behaviors, and challenges and barriers within the health system were elicited. This research is part of a larger study focused on understanding the dynamics shaping mental health perceptions and health seeking behaviours among community members residing in Lebanon.

RESULTS

Findings are organized around a causal loop diagram depicting three central dynamics as described by workshop participants. First, participants linked financial constraints at household levels and the inability to secure one's livelihood with contextual socio-political stressors, principally referring to integration challenges between host communities and Syrian refugees. In a second dynamic, participants linked exposure to war, conflict and displacement to the occurrence of traumatic events and high levels of distress as well as tense family and community relations. Finally, participants described a third dynamic linking cultural norms and patriarchal systems to exposure to violence and intergenerational trauma among Lebanon's populations. When describing help-seeking pathways, participants noted the strong influence of social stigma within both the community and among health professionals; the latter was noted to negatively affect patient-provider relationships. Participants additionally spoke of difficulties in the delivery of mental health services and linked this to the design of the health system itself, noting the current system being geared towards patient centered care, which focuses on the patient's experiences with a disease only, rather than person focused care where providers and patients acknowledge broader structural and social influences on health and work together to reach appropriate decisions for tackling health and other social needs. Barriers to delivery of person focused care include the lack of coherent mental health information systems, limited human capacity to deliver MHPSS services among primary health care staff and inadequate service integration and coordination among the many providers of mental health services in our study contexts. Critically however, provider accounts demonstrate readiness and willingness of health professionals to engage with integrated person focused care models of care.

CONCLUSIONS

Mental ill health is a major public health problem with implications for individual health and wellbeing; in a fragile context such as Lebanon, the burden of mental ill health is expected to rise and this presents substantive challenges for the existing health system. Concrete multi-sectoral efforts and investments are required to (1) reduce stigma and improve public perceptions surrounding mental ill health and associated needs for care seeking and (2) promote the implementation of integrated person focused care for addressing mental health.

Effect of over the counter mouthwashes with and without alcohol on sorption and solubility of bulk fill resins

Background

Composites sorption and solubility can be precursors of several chemical and physical processes, which lead to deleterious effects on the polymer structure. This study evaluated the effect of mouthwashes with and without alcohol on the sorption and solubility of conventional and low viscosity bulk fill resins.

Material and Methods

Four types of Bulk Fill resins (Filtek™ Bulk Fill, X-tra Fil, Filtek™ Bulk Fill Flow and X-tra Base) were submitted to the following mouthwashes: Listerine Cool Mint and Periogard (containing alcohol) and Listerine Zero and Periogard (alcohol-free). The specimens were stored in the mouthwashes for seven days. Solubility and sorption tests were performed according to ISO 4049. Data were analyzed using two-way-ANOVA, followed by Tukey Test. The data were grouped, and a paired t-test was performed to evaluate the effect of alcohol on the properties studied. The p was fixed at 5%.

Results

Resins immersed in alcohol-containing mouthwashes had higher values of sorption and solubility, with the highest sorption rate for X-Tra Base in Listerine Cool Mint treatment (p<0.05). Flow type resins showed higher sorption than conventional viscosity resins, irrespective of the mouthwash used (p<0.05).

Conclusions

Alcohol-containing mouthwashes affected sorption and solubility of bulk fill resins and the composites that presented worse and better performance regarding the studied properties were X-Tra Base and Filtek™ Bulk Fill, respectively.

Key words:Solubility, Sorption, Mouthwashes, Bulk-fill composites.

Effect of home and in-office bleaching systems on the nanomechanical properties of tooth enamel

Objectives

The purpose of this in vitro laboratory study was to gauge the nanomechanical properties of the tooth enamel surface using home and in-office bleaching products.

Methods

Thirty-six extracted lower lateral incisor teeth (sound and without caries, cracks or restorations) were selected. A silicone mould was used to affix the samples in resin after cutting away the roots. Next, the samples were indiscriminately divided into three treatment groups, i.e., 12 teeth in each study group (control, Opalescence Home, and Opalescence Boost), and treated according to their respective group procedures. Surface topography, nano-indentation, and visual analyses were performed. Data were examined statistically using one-way analysis of variance (p < 0.05).

Results

Both experimental bleaching products enhanced the surface roughness when compared to the samples in the control group. However, the control and Opalescence Boost groups showed insignificant differences. The lowest mean nanohardness (GPa) was observed in the Opalescence Boost group (1.56 GPa ± 0.68 GPa). In contrast, the highest mean nanohardness (GPa) was perceived in the control group (3.53 GPa ± 1.06 GPa). The modulus of elasticity was highly affected using Opalescence Boost (182.63 GPa ± 109.13 GPa) when compared to Control (322.69 GPa ± 168.24 GPa). On visual examination, pronounced roughness was observed in both the Opalescence Home and Opalescence Boost groups.

Conclusion

Both teeth whitening products damaged the enamel surface either by roughening the tooth surface or by affecting the nanomechanical properties. Therefore, teeth whitening products may be used, but with great caution.

Depression Illness Representations Among Arabs in Israel: a Qualitative Study Comparing Younger and Older Adults

There has been a noticeable increase in the number of studies assessing perceptions regarding depression (illness representations) among people diagnosed with the disorder. However, these studies have examined mainly younger adults (ages 18 to 65), and very little is known about older adults. This study examined illness representations among younger and older Israeli Arabs with depression based on the Self-Regulation Model (SRM). A total of 12 Israeli Arabs (six younger adults aged 18-64 and six older adults aged 65+) diagnosed with depression took part in semi-structured, in-depth interviews. The majority of the participants in the younger group were female and married, compared to the older group which has a gender equal ratio, half of which are married. The data were analyzed thematically, guided by the SRM illness representations' dimensions (identity; timeline; cause; consequences; control/cure; cyclical and coherence; and emotional representations). Differences between younger and older adults were found in some of the illness representations. Older adults described depression as a chronic illness associated with somatic symptoms, and did not believe in psychological treatment. Younger adults did not perceive depression as chronic, reported cognitive and emotional symptoms, and believed in the efficacy of psychological treatment. Our findings indicated that participants' perceptions about depression appeared to be associated with their age, along with their unique cultural background as they are traditional but undergoing processes of modernization. This study stress the importance of illness representations in intervention programs tailored for different age groups, and considering their specific cultural needs.