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.

Using Functionalized Micron-Sized Glass Fibres for the Synergistic Effect of Glass Ionomer on Luting Material.

This laboratory experiment was conducted with the objective of augmenting the mechanical properties of glass ionomer cement (GIC) via altering the composition of GIC luting powder through the introduction of micron-sized silanized glass fibres (GFs). Experimental GICs were prepared through the addition of two concentrations of GFs (0.5% and 1.0% by weight) to the powder of commercially available GIC luting materials. The effect of GF in set GIC was internally evaluated using micro-CT while the mechanical attributes such as nano hardness (nH), elastic modulus (EM), compressive strength (CS), and diametral tensile strength (DTS) were gauged. Additionally, the physical properties such as water solubility and sorption, contact angle (CA), and film thickness were evaluated. Reinforced Ketac Cem Radiopaque (KCR) GIC with 0.5 wt.% GF achieved improved nH, EM, CS, and DTS without affecting the film thickness, CA or internal porosity of the set GIC cement. In contrast, both GF-GIC formulations of Medicem (MC) GIC showed the detrimental effect of the GF incorporation. Reinforcing KCR GIC with 0.5 wt.% silanized GFs could improve the physical and mechanical attributes of luting material. Silanized GF, with optimal concentration within the GIC powder, can be used as a functional additive in KCR GIC with promising results.

Utilizing an Oxidized Biopolymer to Enhance the Bonding of Glass Ionomer Luting Cement Particles for Improved Physical and Mechanical Properties.

This study aimed to determine the reinforcing effect of two weight ratios of Gum Arabic (GA) natural biopolymer, i.e., 0.5% and 1.0% in the powdered composition of glass ionomer luting cement. GA powder was oxidized and GA-reinforced GIC in 0.5 and 1.0 wt.% formulations were prepared in rectangular bars using two commercially available GIC luting materials (Medicem and Ketac Cem Radiopaque). The control groups of both materials were prepared as such. The effect of reinforcement was evaluated in terms of microhardness, flexural strength (FS), fracture toughness (FT), and tensile strength (TS). The internal porosity and water contact angle formation on the study samples were also evaluated. Film thickness was measured to gauge the effect of micron-sized GA powder in GA-GIC composite. Paired sample t-tests were conducted to analyze data for statistical significance (p < 0.05). The experimental groups of both materials containing 0.5 wt.% GA-GIC significantly improved FS, FT, and TS compared to their respective control groups. However, the microhardness significantly decreased in experimental groups of both cements compared to their respective control groups. The addition of GA powder did not cause a significant increase in film thickness and the water contact angle of both 0.5 and 1.0 wt.% GA-GIC formulations were less than 90o. Interestingly, the internal porosity of 0.5 wt.% GA-GIC formulations in both materials were observed less compared to their respective control groups. The significantly higher mechanical properties and low porosity in 0.5 wt.% GA-GIC formulations compared to their respective control group indicate that reinforcing GA powder with 0.5 wt.% in GIC might be promising in enhancing the mechanical properties of GIC luting materials.

Effectiveness of photodynamic therapy on clinical and biomarker related periodontal parameters and oral health related quality of life (OHRQoL) in Parkinson's disease patients with stage III periodontitis.

AIMS: To evaluate the clinical, radiographic, immune modulatory biomarkers and quality of life with the application of photodynamic therapy (PDT) as an adjunctive treatment to dental scaling and root planing (SRP) in patients with chronic periodontitis and Parkinson's disease. METHODOLOGY: Individuals who had a confirmed diagnosis of stage III periodontitis and stage 4 Parkinson's disease according to Hoehn and Yahr scale were involved in this study. The participants were divided into two groups: Group SRP (n = 25) received traditional dental scaling procedure including full-mouth debridement and disinfection, and Group PDT + SRP (n = 25) received both traditional cleaning procedures along with adjunctive chloro­aluminum phthalocyanine (CAPC) gel (0.005% concentration) mediated PDT. CAPC photosensitizer was activated using a diode laser (wavelength=640 nm, energy=4 J, 150 mW power, and overall power density of 300 J/cm2) for 60 s. The study measured clinical parameters such as plaque score (PI), bleeding on probing (BOP), probing depth (PD), clinical attachment loss (CAL), and radiographic alveolar bone loss (ABL). Proinflammatory cytokine levels such as interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α) and oral health related quality of life were also assessed. RESULTS: The mean age of patients in Group SRP was 73.3 years, while the mean age in Group PDT + SRP was 71.6 years. The PDT + SRP group showed a significant reduction in all clinical parameters at 6 and 12 months compared to the SRP group alone (p < 0.05). IL-6 and TNF-α levels were significantly reduced in the PDT + SRP group at 6 months compared to the SRP group alone (p < 0.05). However, at 12 months, both groups showed comparable TNF-α levels. The results showed that Group PDT + SRP had significantly lower OHIP scores compared to Group SRP, with a mean difference of 4.55 (95% confidence interval [CI]: 1.98 to 7.12) (p < 0.01). CONCLUSION: Combined SRP with PDT showed significant improvement compared to SRP alone in terms of clinical parameters, cytokine levels, and oral health-related quality of life in individuals diagnosed with stage III periodontitis associated with Parkinson's disease.

Oxidized Natural Biopolymer for Enhanced Surface, Physical and Mechanical Properties of Glass Ionomer Luting Cement.

This laboratory investigation aimed to synthesize and characterize micron-sized Gum Arabic (GA) powder and incorporate it in commercially available GIC luting formulation for enhanced physical and mechanical properties of GIC composite. Oxidation of GA was performed and GA-reinforced GIC in 0.5, 1.0, 2.0, 4.0 & 8.0 wt.% formulations were prepared in disc-shaped using two commercially available GIC luting materials (Medicem and Ketac Cem Radiopaque). While the control groups of both materials were prepared as such. The effect of reinforcement was evaluated in terms of nano hardness, elastic modulus, diametral tensile strength (DTS), compressive strength (CS), water solubility and sorption. Two-way ANOVA and post hoc tests were used to analyze data for statistical significance (p < 0.05). FTIR spectrum confirmed the formation of acid groups in the backbone of polysaccharide chain of GA while XRD peaks confirmed that crystallinity of oxidized GA. The experimental group with 0.5 wt.% GA in GIC enhanced the nano hardness while 0.5 wt.% and 1.0 wt.% GA in GIC increased the elastic modulus compared to the control. The CS of 0.5 wt.% GA in GIC and DTS of 0.5 wt.% and 1.0 wt.% GA in GIC demonstrated elevation. In contrast, the water solubility and sorption of all the experimental groups increased compared to the control groups. The incorporation of lower weight ratios of oxidized GA powder in GIC formulation helps in enhancing the mechanical properties with a slight increase in water solubility and sorption parameters. The addition of micron-sized oxidized GA in GIC formulation is promising and needs further research for improved performance of GIC luting composition.

Effectiveness of photodynamic therapy adjunct to oral debridement in improving clinical, microbiological, and pain in necrotizing ulcerative gingivitis.

To evaluate the efficacy of photodynamic therapy (PDT) as adjunctive to oral debridement (OD) in the improvement of clinical, microbiological, and pain in patients with necrotizing ulcerative gingivitis (NUG). Patients with NUG were split into two groups: Group-OD + PDT received PDT with OD, while Group-OD underwent OD alone. Clinical inflammatory parameters including full mouth plaque scores (FMPS), full mouth bleeding scores (FMBS), and probing depth (PD) were assessed. Fusobacterium nucleatum and Prevotella intermedia were analyzed using the polymerase chain reaction technique. Pain examination was done using various pain scales. Group PDT + OD showed more reduction in FMPS, FMBS, and greater reduction in F. nucleatum and P. intermedia count compared to group OD at 12 weeks follow up (p < 0.01). Group PDT + OD showed significantly lower pain scores at 12 weeks (p < 0.05). PDT was more effective in improving clinical parameters, and reducing bacterial counts and pain in NUG patients than dental scaling alone.

Effect of Nitrogen in Combination with Different Levels of Sulfur on Wheat Growth and Yield.

As macronutrients, management of nitrogen (N) and sulfur (S) is prime in importance when wheat is cultivated. Both have a significant impact on the improvement of growth and yield attributes. In addition, S and N also play an imperative role in the enhancement of seed protein contents. However, the need of the time is the selection of their optimum application rate for the achievement of maximum wheat productivity. That is why the current study was planned to examine the impact of variable application rates of S and N on wheat. There are 12 treatments, i.e., control (no nitrogen (0N) + no sulfur (0S)), 40 kg/ha N (40N + 0S), 80 kg/ha N (80N + 0S), 120 kg/ha N (120N + 0S), 30 kg/ha sulfur (30S), 40N + 30S, 80N + 30S, 120N + 30S, 60 kg/ha sulfur (60S), 40N + 60S, 80N + 60S, and 120N + 60S, applied in three replications. The results showed that plant height, grains/spike, spike/m2, and 1000 grain weight were significantly improved by the addition of 120N + 60S. A significant enhancement of grain N contents, N uptake, and protein contents of wheat validated the efficient role of 120N + 60S over 0N and 0S. In conclusion, 120N + 60S is a better treatment for the achievement of maximum wheat yield. More investigations under variable soil textures and climatic conditions are suggested under different climates to declare 120N + 60S as the best amendment for wheat growth and yield improvement.

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.

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.

Antimicrobial photodynamic therapy using chloro-aluminum phthalocyanine for treating advanced stage-III periodontitis in smoking patients.

PURPOSE: To evaluate the bacterial, clinical, and cytokine profile of adjunctive photodynamic therapy using chloro-aluminum phthalocyanine (CAP/aPDT) with root surface debridement (RSD) versus RSD alone in cigarette smokers (CS) and never-smokers (NS) during the period of 6 months. METHODS: Twenty-nine patients [CS - 14 and NS - 15] were recruited for the trial having stage-III periodontitis. All candidates from the study groups were subjected to a split-mouth treatment technique receiving CAP/aPDT + RSD and RSD alone. Periodontal parameters including plaque levels (PL), bleeding on probing (BP), probing depth (PD), clinical attachment loss (CAL), and marginal bone loss (MBL) were assessed. Polymerase chain reaction (qPCR) assay was used to analyze the copy numbers of Porphyromonas gingivalis (Pg) and Tannerella forsythia (Tf). Levels of tumor necrosis factor-alpha (TNF-α) interleukin (IL)-6 in the crevicular fluid were evaluated by enzyme-linked immunosorbent assay (ELISA). RESULTS: CAP/aPDT+RSD decreased BP in smokers after 6 months (p < .05). Probing depth and CAL reported statistically significant reductions within both CAP/aPDT+RSD and RSD groups and also within the NS and CS (p < .05). Pg and Tf stayed elevated in smokers at the 6-month evaluation period (p < .01). Only CAP/aPDT+RSD significantly decreased Pg and Tf at 3- and 6-month follow-up in smokers (p < .05). CAP/aPDT+RSD showed decreased IL-6 levels in the NS during the 6-month follow-up (p < .01). TNF-α levels were significantly reduced in the CS group with CAP/aPDT+RSD and RSD alone until 6 months (p < .01). CONCLUSION: CAP-mediated aPDT along with nonsurgical periodontal therapy helped to improve the bacteriological outcomes among smokers and never-smokers with stage-III CP patients.

Chloro-aluminum phthalocyanine-mediated photodynamic therapy in the treatment of stage-II chronic periodontitis among smokers.

PURPOSE: To assess the clinical periodontal, bacterial, and immunological outcomes of chloro-aluminum phthalocyanine-mediated photodynamic therapy (PDT) as an adjunct to dental scaling (DS) versus DS alone among cigarette smokers (CS) and never-smokers (NS). METHODS: A total of 26 patients (13 CS and 13 NS) with clinical and radiographic diagnosis of stage-II chronic periodontitis were recruited. Each patient from both groups were subjected with two parallel therapies (split-mouth): PDT + DS (test side) and DS alone (control side). Periodontal parameters were investigated by evaluating plaque scores (PS), bleeding on probing (BOP), probing depth (PD), clinical attachment loss (CAL), and alveolar bone loss (ABL). Subgingival plaque was collected to detect and quantify Porphyromonas gingivalis and Tannerella forsythia using real-time quantitative polymerase chain reaction (RT-qPCR) assay. Gingival crevicular fluid was sampled for the quantification of interleukin (IL)-1ß and tumor necrosis factor-alpha (TNF-α) using enzyme linked immunosorbent assay. All assessments were performed at baseline, 3 months, and 6 months. RESULTS: Bleeding on probing was significantly reduced at 6 months after PDT + DS in CS groups (p < .05). Mean PD and CAL significantly reduced after both PDT + DS and DS subgroups and among NS and CS groups (p < .05). At 6 months follow-up, the copy number of both P. gingivalis and T. forsythia remained significantly high in CS group (p < .01). Only PDT + DS subgroup in CS significantly reduced the counts of P. gingivalis and T. forsythia at 3 months and 6 months (p < .05). Only at 6 months did PDT + DS showed statistically significantly reduced IL-1ß levels in the NS group (p < .01). TNF-α levels significantly reduced in CS group with PDT + DS and DS alone at both 3 months and 6 months follow-up (p < .01). CONCLUSION: Chloro-aluminum phthalocyanine-mediated PDT helped to improve the non-surgical periodontal therapy outcomes among stage-II chronic periodontitis patients among smokers and never-smokers.

Mechanical Properties of the Modified Denture Base Materials and Polymerization Methods: A Systematic Review.

Amidst growing technological advancements, newer denture base materials and polymerization methods have been introduced. During fabrication, certain mechanical properties are vital for the clinical longevity of the denture base. This systematic review aimed to explore the effect of newer denture base materials and/or polymerization methods on the mechanical properties of the denture base. An electronic database search of English peer-reviewed published papers was conducted using related keywords from 1 January 2011, up until 31 December 2021. This systematic review was based on guidelines proposed by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The search identified 579 papers. However, the inclusion criteria recognized 22 papers for eligibility. The risk of bias was moderate in all studies except in two where it was observed as low. Heat cure polymethyl methacrylate (PMMA) and compression moulding using a water bath is still a widely used base material and polymerization technique, respectively. However, chemically modified PMMA using monomers, oligomers, copolymers and cross-linking agents may have a promising result. Although chemically modified PMMA resin might enhance the mechanical properties of denture base material, no clear inferences can be drawn about the superiority of any polymerization method other than the conventional compression moulding technique.

Minocycline incorporated cobalt oxide nanoparticles in dental sealants: An in vitro study.

The purpose of this study was to introduce antibacterial property to pits and fissure sealant (PFS) in order to mitigate the major clinical problems associated with PFS, such as microleakage and secondary caries. We prepared a pH reliant cobalt oxide nanoparticle incorporated with minocycline (MNC@CO) and characterized to investigate its antibacterial potential against Streptococcus sobrinus. The physiochemical, morphological, and drug release kinetics at different pH (7.4, 5.0, and 3.5) from nanoparticles were investigated. The MNC@CO were added at 2.5% and 5.0% into experimental PFS and characterized for their antibiofilm capacity, biocompatibility, and mechanical properties including compressive and flexural strength. The groups 2.5% and 5.0% has shown statistically significant antimicrobial capacity against S. sobrinus compared to control (p < .05). The highest percentage of MNC release at different pH (especially at pH 5.0 and 3.5) was observed from 5.0% MNC@CO doped PFS. The PFS doped with 2.5% MNC@CO showed a highest compressive strength (110 MPa) over a period of 70 days as compared to 5.0% MNC@CO (75 MPa) and control (80 MPa). The flexural strength of both experimental groups was lower for both time points (24 h and 30 days) than control. In conclusion, the present study found that 2.5% MNC@CO doped PFS showed considerable anti-biofilm potential without compromising mechanical properties.

Resin modified glass ionomer bonded to caries affected dentin disinfected with carbon dioxide laser, diode lasers, bee glue and photosensitizing agents: An estimation of bond strength.

AIM: The present in vitro study was carried out to evaluate the effect of different cavity disinfectants chlorhexidine (CHX), riboflavin (RF), diode laser (DL), carbon dioxide laser (CO2), and Propolis on the bond values of resin-modified glass ionomer cement (RMGIC) restoration bonded to caries affected dentin (CAD) MATERIALS AND METHODS: Forty multi-rooted mandibular molars were adapted in self-cure acrylic resin blocks up to the level of the cementoenamel junction so that only the crown portion of the tooth remained visible. Silicon carbide discs of 1200 and 600 grits were then used to remove infected dentin. However, CAD was left behind to use as a substrate for restoration. All samples were randomly divided into five groups based on the method of disinfection. group 1: Propolis, group 2: CHX, group 3:RF activated by PDT, group 4: CO2 laser, and group 5: DL. RMGIC restoration was then placed on these disinfected samples. Samples were kept in an incubator keeping humidity at 100 % and temperature at 37 °C for about 24 hrs. All samples were then placed in a Universal testing machine to measure SBS. Failure modes were identified using a stereomicroscope. ANOVA test was used to analyze intergroup comparison. Tukey HSD test was used to evaluate multiple group comparisons. The level of significance was set at a p < 0.05 value. RESULTS: Group 2 specimens disinfected with CHX established the highest SBS value (17.85±1.09 MPa). Whereas, Group 5 specimens in which CAD was disinfected with DL demonstrated the lowest SBS (10.36±0.33MPa). CONCLUSION: CO2 has the potential to be used as an alternate to CHX for caries-eaffected dentin disinfection. However, Riboflavin activated by photodynamic therapy; Diode laser, and Propolis as cavity disinfectant prior bond to resin-modified glass ionomer is not recommended and needs further probing.

Role of Riboflavin; Curcumin photosensitizers and Ozone when used as canal disinfectant on push-out bond strength of glass fiber post to radicular dentin.

AIM: To assess the efficacy of photosensitizers (CP, riboflavin) and gaseous ozone in comparison to the conventional radicular dentin disinfectant (NaOCl) on push-out bond strength (PBS) of PFRC post cemented to radicular dentin. MATERIAL AND METHOD: Human single-rooted teeth were collected, steriled implanted in polyvinyl pipes up to a cement-o-enamel junction and de coronated. Cleaning and shaping of the canal were performed using the crown down technique followed by obturation of the canal space. Canal space was prepared using peso reamers and samples were divided into four groups based on types of canal disinfectant protocols. Group 1: Riboflavin+ 17%EDTA; group 2: Curcumin Photosensitizer + 17% EDTA; group 3: Gaseous Ozone disinfection (O3) +17% EDTA and group 4 control 2.5% NaOCl +17% EDTA. Within the canal space, fiber post was cemented and cured, and thermocycled. PBS was evaluated using a Universal testing machine (UTM) and failure modes using a stereomicroscope at 40x magnification. One-way analysis of variance (ANOVA) was used to determine the mean and standard deviation of push-out bond strength (PBS). The Tukey multiple comparison tests (p = 0.05) was used to compare the means of PBS. RESULTS: The highest PBS was displayed in group 2 CP+ 17% EDTA at all three root levels, coronal (8.81±0.61), middle (7.77±0.55), and apical (5.25±0.61). The lowest PBS was revealed in group 4, disinfected with 2.5% NaOCl +17% EDTA (control) at coronal (6.12±0.54), middle (5.46±0.84), and apical (3.00±1.88) levels. The most prevailed fracture mode was an adhesive failure (cement-dentin interface). CONCLUSION: Radicular dentin disinfected with PDT using CP, riboflavin, and O3 displayed similar PBS at all root segments. NaOCl is a convenient, traditional, and commonly used disinfectant, and it's effects on PBS is still controversial.

Photodynamic therapy and other pretreatment methods on epoxy-based glass fiber post on the push-out bond strength to radicular dentin.

AIM: To assess the push-out bond strength (PBS) of glass fiber post (GFP) conditioned using different surface treatment regimens bonded to radicular dentin MATERIAL AND METHODS: Sixty central incisors and canine were collected and disinfected. Decoronation following working length was determined using K-file. Rotary file system was used for cleaning and shaping. Canals of all samples were dried with paper points and obturated with gutta percha. Canal space was prepared with peso reamers. Now samples were randomly allocated into six groups based on pretreatment of GFP. Post in group 1 treated with 9% HFA+ Silane, post in group 2 surface treated with silane only, Post in group 3 surface treated with airborne particle (50 µm), group 4 post conditioned with photodynamic therapy (PDT), group 5 post pretreatment was performed with MBP and in group 6 GFP was not treated. Conditioned and non-conditioned posts were positioned in canal space and cemented. Tooth were sectioned coronally, middle and apically. Sections were positioned in universal testing machine (UTM) and debonded surfaces were evaluated for failure modes. The means and standard deviations of PBS were examined using one-way analysis of variance (ANOVA). RESULTS: Coronal third of group 3 in which posts were sandblasted using airborne Al2O3 particle presented the highest PBS (11.21±0.64 MPa). Whereas, an apical section of group 4 in which posts were treated with PDT exhibited the lowest bond integrity. CONCLUSION: Sandblasting using airborne particles (50 µm) and hydrogen peroxide (H3PO4) conditioned with GFP exhibited significantly higher bond strength as compared to the control. However, PDT decreases the PBS of fiber post with the root dentin.

Effectiveness of photodynamic therapy on bonding strength and failure modes of fiber-posts in c-shaped treated root canals.

AIM: The present study aimed to assess the push-out bond strength (PBS) and failure modes of fiber-posts after photodynamic therapy (PDT) and Erbium yttrium scandium gallium garnet (Er,Cr:YSGG) in c-shaped canals. METHODS: Sixty molars with c-shaped root configuration were studied. The endodontic prepared teeth specimen were equally randomized into four groups: i) photodynamic therapy (PDT); ii) Er,Cr:YSGG; iii) chlorhexidine and; iv) control group. Post root filling, 10 mm space was prepared for insertion of post in the root canals. The push-out bond strength was evaluated using Universal testing machine. Modes of failure were evaluated as adhesive, cohesive and admixed. Mean values were computed between groups using Kruskal-Wallis test followed by Bonferroni post hoc test. Comparison between two thirds of root sections were analyzed using Friedman test. P-value was set at 0.05 or less. RESULTS: Specimens treated with PDT reported the highest mean PBS (8.56 ± 2.12 MPa), while the lowest PBS was observed in NaOCl group (6.92 ± 2.21 MPa). Thirteen failures were observed at the adhesive post interface, whereas 22 failures were found at the interface forming between the dentin surface and adhesive. Similarly, 9 failures were categorized as mixed. For PDT group, a sum of 3 failures and 4 failures were noted at the apical and cervical points. CONCLUSION: The specimens treated with PDT showed the highest push out bond strength with least number of failures.in c-shaped root canals.

Fascial space odontogenic infections: Ultrasonography as an alternative to magnetic resonance imaging.

BACKGROUND: The introduction of modern diagnostic tools has transformed the field of maxillofacial radiology. Odontogenic infection and fascial space involvement have been evaluated with many diagnostic tools, including ultrasonography (USG) and magnetic resonance imaging (MRI). AIM: To explore USG as an alternative model to MRI in the detection of fascial space spread of odontogenic infections. METHODS: Among 20 patients, 50 fascial spaces were clinically diagnosed with odontogenic infection and included in this prospective study. Fascial space infection involvement was examined by USG and MRI. Results were compared for both and confirmed by microbiological testing. RESULTS: Ultrasonography identified 42 (84%) of 50 involved fascial spaces. Whereas MRI identified all 50 (100%). USG could stage the infections from edematous change to cellulitis to complete abscess formation. CONCLUSION: MRI was superior in recognizing deep fascial space infections compared to USG. However, USG is a significant addition and has a definite role in prognosticating the stage of infection and exact anatomic location in superficial space infections.

Interfacial Adhesion of a Semi-Interpenetrating Polymer Network-Based Fiber-Reinforced Composite with a High and Low-Gradient Poly(methyl methacrylate) Resin Surface.

The research aimed to determine the tensile bond strength (TBS) between polymerized intact and ground fiber-reinforced composite (FRC) surfaces. FRC prepregs (a reinforcing fiber pre-impregnated with a semi-interpenetrating polymer network (semi-IPN) resin system; everStick C&B) were divided into two groups: intact FRCs (with a highly PMMA-enriched surface) and ground FRCs (with a low PMMA gradient). Each FRC group was treated with: StickRESIN and G-Multi PRIMER. These groups were further divided into four subgroups based on the application time of the treatment agents: 0.5, 1, 2, and 5 min. Next, a resin luting cement was applied to the FRC substrates on the top of the photo-polymerized treating agent. Thereafter, weight loss, surface microhardness, and TBS were evaluated. Three-factor analysis of variance (p ≤ 0.05) revealed significant differences in the TBS among the FRC groups. The highest TBS was recorded for the intact FRC surface treated with G-Multi PRIMER for 2 min (13.0 ± 1.2 MPa). The monomers and solvents of G-Multi PRIMER showed a time-dependent relationship between treatment time and TBS. They could diffuse into the FRC surface that has a higher PMMA gradient, further resulting in a high TBS between the FRC and resin luting cement.

Knowledge and attitude of dental professionals toward COVID-19 in Riyadh, Saudi Arabia: a cross-sectional survey.

Background: Coronavirus disease-2019 (COVID-19) is a life-threatening global pandemic. The dental profession is considered a high-risk group in the transmission of the responsible virus. Objective: To assess the knowledge and attitude among dental professionals in response to the COVID-19 pandemic. Methods: We conducted a cross-sectional study of dental graduates, interns, postgraduates, and dental faculty from May to July 2020. A standardized questionnaire was developed to assess knowledge and attitude of 650 participants. The questionnaire comprised 14 questions to assess general knowledge about COVID-19, 11 questions regarding knowledge about prevention of COVID-19 in dental practice, and 10 questions regarding the attitude toward preventing COVID-19. Results: Among the study population, only 376 (57.8%) knew the causative virus for COVID-19. Only 425 (65.3%) knew about rinsing the mouth with an antimicrobial solution or 1% hydrogen peroxide before the dental procedure. Regarding the hand hygiene guidelines, 357 (54.9%) had knowledge of the Centers for Disease Control and Prevention (CDC) and 377 (58.0%) about World Health Organization (WHO) guidelines. At the time of our survey, 72% of the participants showed sufficient knowledge, while 28% had low or insufficient knowledge about COVID-19. Conclusion: While there was a lack of knowledge among dental professionals in Riyadh, Saudi Arabia about COVID-19, there was an excellent positive attitude toward preventing disease. Greater awareness is needed to control the spread of this disease.