Knowledge, Attitude, and Practices toward the Novel Coronavirus Infection in Dental Laboratories in the Kingdom of Saudi Arabia: Cross-Sectional Study.

This study aimed to assess dental technologists/technicians knowledge, attitudes, and practice during the COVID-19 pandemic in Saudi Arabia. This cross-sectional study was conducted among workers in dental laboratories in Saudi Arabia. A validated questionnaire was developed based on previous literature and distributed online. The questionnaire assessed the study population's knowledge, attitude, and practice regarding infection control protocol for COVID-19. Descriptive statistics of categorical variables were conducted. The response rate was 58.3%, where most respondents are male at a rate of 97%. Most of the participants (82%) were aware of the various infection control measures for COVID-19 in a dental laboratory. Forty-eight participants showed a level of knowledge range between 80 and 100%, while 27 and 30 participants reported moderate and low level of knowledge, respectively. Only 67% of the participants strongly agree that dental cast and fabricated/repaired restorations should be transferred in a very close and protective package to control infection. About 70% of participants indicated they always wear protective gear/goggles and should be warned while working in the dental laboratory. As the pumice slurry was utilized frequently to clean and polish the prostheses, 66% of participants agreed that pumice slurry should be always changed regularly. Regarding COVID-19 infection control procedures, dental technologists/technicians showed good knowledge, attitude, and practice; however, considering how infectious the virus is, more measures should be taken into consideration. Effective communication and collaboration between the laboratory and the dental clinic are essential for infection control.

Psychological impact of COVID-19 lockdown period on students of healthcare colleges.

Background: The coronavirus disease 2019 (COVID-19) pandemic globally caused depression, anxiety, and post-traumatic stress. Mental health was affected by social separation, curfews, school and business closures, economic deterioration, and government objectives. This study intends to assess the influence of the post-COVID-19 lockdown period on the psychological health of students enrolled in health colleges at King Saud University, Saudi Arabia. Materials and Methods: A cross-sectional study was conducted among students of healthcare colleges at King Saud University. We used a validated questionnaire of the Generalized Anxiety Disorder Assessment (GAD-7) and the Perceived Stress Scale (PSS-10). The questionnaire was sent to participants via google forms link through WhatsApp, e-mail, and other social media platforms. A total of 311 participants responded to the questionnaire. Descriptive analysis and a Chi-square test were performed for qualitative data analysis. Results: Among study participants, males were 50.4% and females were 49.6%. About 63% of the students attended a training session on COVID-19 prevention strategies. About 37% of the participants were from the College of Medicine, 27% were from the College of Dentistry, 21% from the College of Pharmacy, 5% from the College of Applied Medical Sciences, and 10% from the College of Nursing. The average anxiety score was 9.84, and the perceived stress score (PSS) was 23.95. 44.1% of students reported mild anxiety, and 1.6% suffered severe anxiety. High stress was perceived by 24.1% of the students, and 75.2% perceived a moderate stress level. No significant association was reported between gender, stress, and anxiety. Similarly, no association was found between stress and the year of study. However, a significant association was found between the year of study and anxiety (P = 0.015). Conclusion: To the limitation of the study, the analysis revealed that COVID significantly influences students' psychological health. Such findings can be used to develop psychological interventions and susceptible populations and execute appropriate mental health policies and programs targeting student communities.

Evaluation of medical equipment maintenance and skilled manpower requirement among private dental centres in Riyadh, Saudi Arabia: A pilot study.

BACKGROUND: Adequate equipment maintenance is necessary to ensure efficient dental care facilities and satisfactory medical equipment performance. OBJECTIVE: This study aimed to assess maintenance practices and manpower adequacy in private dental centres (DCs) across Riyadh, Saudi Arabia. METHODS: A questionnaire was designed to evaluate equipment maintenance and manpower strength based on international and national standards. Thirty-three private DCs were visited in-person with the designed questionnaire to conduct the study. The Chi-square test and t-test were performed. RESULTS: Only 21 dental centres had a scheduled maintenance plan for medical equipment, whereas the rest had no plan. Furthermore, only 22 DCs maintained equipment maintenance records, while 11 DCs did not have any records. Additionally, the study found a lack of trained personnel to handle medical equipment and overall inadequate maintenance practices. Significant differences were observed between the responses for many questions (p< 0.05). CONCLUSION: These findings increase health risks to both the patient and the user. To address these issues, DC administrators should implement stricter measures to adhere to local DCs standards and hire qualified personnel who can periodically maintain and repair medical equipment.

Knowledge of the monkeypox 2022 outbreak among dental hygienists and students in Saudi Arabia: A cross-sectional study.

OBJECTIVE: This study aimed to assess the knowledge of monkeypox infection among dental hygiene professionals and students in Saudi Arabia. METHODS: A cross-sectional study was conducted among a convenience sample of dental hygiene professionals (n = 259). The questionnaire was developed based on previous literature, and descriptive analysis and a Chi-square test were performed. RESULTS: A total of 159 dental hygienists responded to the questionnaire. Results indicated that only 1.7% had good knowledge, 7.7% had moderate knowledge and 90.6% had low knowledge of the monkeypox outbreak. The mean knowledge scores varied among dental hygiene students, practitioners and faculty members. Significant group differences were observed for some questions (p < 0.05). CONCLUSION: Our study concludes that dental hygienists had moderate to low level of knowledge of the monkeypox infection and its implications for oral health and patient care, indicating a need for more education on the subject.

The Effect of Femtosecond Laser Surface Patterns on the Effectiveness of Resin Composite to Zirconia Bonding.

This laboratory study aimed to evaluate the effect of different surface patterns using femtosecond laser treatment on the enclosed mold shear bond strength (EM-SBS) of resin composite to zirconia (ZrO2) surfaces and to contrast it with the widely used tribochemical silica coating (TBC) surface conditioning method. A set of fifteen rectangular ZrO2 blocks were randomly divided into five groups according to surface pretreatment: Control G0-no treatment; G1-TBC with silane application; G2-femtosecond laser irradiation with horizontal lines 30 µm apart; G3-femtosecond laser irradiation with horizontal lines 15 µm apart; and G4-femtosecond laser irradiation with cross lines 30 µm apart. The pretreated surfaces were characterized by a surface profilometer, tensiometer and scanning electron microscope. The EM-SBS of resin composite stubs to ZrO2 was measured followed by fractographic analysis. The surface roughness and water contact angle were observed to be statistically higher among the femtosecond laser groups compared to the TBC and control groups. The G4 group exhibited the highest EM-SBS among all the groups, irrespective of the ageing conditions used. At the end of 5000 thermocycles, G4 exhibited EM-SBS of 14.05 ± 4.21 MPa compared to 13.80 ± 3.01 MPa in G1 and 5.47 ± 0.97 MPa in G0. The two-way ANOVA revealed a significant effect of both study groups and ageing conditions on the EM-SBS (p < 0.001). Utilization of femtosecond laser technology holds promise as a potential and alternative mechanical retention approach for enhancing the bonding strength of the resin composite to ZrO2.

Trueness, Flexural Strength, and Surface Properties of Various Three-Dimensional (3D) Printed Interim Restorative Materials after Accelerated Aging.

Various 3D printing systems for interim fixed dental restorations are commercially available. This study aimed to evaluate the physical and mechanical properties of 3D printed resins used for interim restorations fabricated using various 3D printing systems and printing angulations after accelerated aging. Three different interim restorative materials were provided and printed using their specific 3D printing systems (A: NextDent; B: Asiga; C: Nova3D), and the testing specimens from each system were printed at two building angles: (1) 0° and (2) 90°. The six groups were A1, A2, B1, B2, C1, and C2, with sixteen specimens per group. Half of the specimens in each group (N = 8) were subjected to accelerated aging, including simulated brushing and thermocycling. Three-point bending, surface roughness, and Vickers microhardness tests were performed. Two-way ANOVA and Fisher's multiple tests were used for statistical analyses. The most accurate systems were found in groups C1 and C2 for length, A1 and B1 for width, and A1 and C1 for height. The specimen trueness only changed after aging for groups B1, B2, and C1. The flexural strength of the A2 group (151 ± 7 MPa) before aging was higher than that of the other groups, and the strength decreased after aging only for groups A1 and A2. The flexural strength, microhardness, and surface roughness of the 3D printed interim resins after aging varied depending on the material, system used, and printing angle.

Andersen health care utilization model: A survey on factors affecting the utilization of dental health services among school children.

BACKGROUND: Children's quality of life, academic performance, and future achievement can all be negatively affected by poor dental health. The present study aimed to assess the need for dental health services and the factors influencing their utilization using the Andersen health care utilization model among school children. METHODS: The current cross-sectional study was conducted among schoolchildren aged 13 to 15 in Bangalore, India (n = 1100). A questionnaire was developed using the concepts of the Andersen healthcare usage model. The parents of the children filled out the questionnaire. The factors were investigated using bivariate analysis and multivariate logistic regression analysis. RESULTS: About 78.1% of the children did not utilize dental health services. Regarding the reasons for not visiting a dentist, 65.8% said they did not have a dental problem, and 22.2% said they could not afford it. Bivariate analysis showed that age, gender, education level, occupation of the family's head of household, monthly family income, socioeconomic status, perceived oral health problems, accessibility of dental health facilities, and parental attitudes toward their children's oral health were significantly associated with using dental health services (p<0.05). Multiple regression analysis showed dental health service utilization was directly related to age (OR = 2.206), education, family size (OR = 1.33), and brushing frequency twice a day (OR = 1.575) with no significant relationship between distance to reach the dental facility, the number of dental visits, and socioeconomic status. CONCLUSION: Dental health service utilization was low in the past year. The age, number of family members, parent's education level, travel time to the dental facility, the child's oral health behaviors, and positive parental attitude all play a role in a children's utilization of dental health service.

Study of Streptococcus mutans in Early Biofilms at the Surfaces of Various Dental Composite Resins.

BACKGROUND: Biofilm deposit on the composite restoration is a common phenomenon and bacterial growth follows the deposition. The study aims to evaluate Streptococcus mutans (S. mutans) early biofilm formation on the surfaces of various dental composite resins by using the real-time quantitative polymerase chain reaction (qPCR) technique. MATERIALS AND METHODS: Thirty-two discs, where eight discs were in each group of Filtek Supreme Ultra (FSU; 3M, St. Paul, MN), Clearfil AP-X (APX; Kuraray Noritake Dental Inc., Tokyo, Japan), Beautifil II (BE2; Shofu, Inc., Kyoto, Japan), and Estelite Sigma Quick (ESQ; Tokuyama Dental, Tokyo, Japan), were fabricated and subjected to S. mutans biofilm formation in an oral biofilm reactor for 12 hours. Contact angles (CA) were measured on the freshly fabricated specimen. The attached biofilms underwent fluorescent microscopy (FM). S. mutans from biofilms were analyzed using a qPCR technique. Surface roughness (Sa) measurements were taken before and after biofilm formation. Scanning electron microscopy (SEM), including energy dispersive X-ray spectrometer (EDS) analysis, was also performed for detecting relative elements on biofilms. RESULTS: The study showed that FSU demonstrated the lowest CA while APX presented the highest values. FM revealed that condensed biofilm clusters were most on FSU. The qPCR results indicated the highest S. mutans DNA copies in the biofilm were on FSU while BE2 was the lowest (p < 0.05). Sa test signified that APX was significantly the lowest among all materials while FSU was the highest (p < 0.05). SEM displayed areas with apparently glucan-free S. mutans more on BE2 compared to APX and ESQ, while FSU had the least. Small white particles detected predominantly on the biofilms of BE2 appeared to be Si, Al, and F extruded from the resin. CONCLUSION: Differences in early biofilm formation onto various composite resins are dependent on the differences in material compositions and their surface properties. BE2 showed the lowest quantity of biofilm accumulation compared to other resin composites (APX, ESQ, and FSU). This could be attributed to BE2 proprieties as a giomer and fluoride content.

Coffee Staining and Simulated Brushing Induced Color Changes and Surface Roughness of 3D-Printed Orthodontic Retainer Material.

This in vitro study evaluated the influence of combined coffee staining and simulated brushing-induced color changes and surface roughness on 3D-printed orthodontic retainers. Specimens measuring 10 × 10 × 0.75 mm3 were obtained either by conventional vacuum forming or 3D printing at four print angulations (0°, 15°, 30°, and 45°) (n = 10). The prepared specimens were immersed in a coffee beverage and then mechanically brushed using a simulating device. The specimen's color difference (ΔE) and surface roughness (Ra) were quantified using a spectrophotometer and a non-contact profilometer, respectively. The highest and lowest mean ΔE values were recorded for the 3D-printed-45° (4.68 ± 2.07) and conventional (2.18 ± 0.87) groups, respectively. The overall mean comparison of ΔE between the conventional and 3D-printed groups was statistically significant (p < 0.01). After simulated brushing, all groups showed a statistically significant increase in the Ra values (p < 0.01). The highest Ra was in the 3D-printed-45° (1.009 ± 0.13 µm) and conventional (0.743 ± 0.12 µm) groups, respectively. The overall ΔE of 3D-printed orthodontic retainers was not comparable to conventional VFRs. Among the different angulations used to print the retainers, 15° angulations were the most efficient in terms of color changes and surface roughness and were comparable to conventional VFRs.

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.

Surface Characteristics and Adhesion of Veneering Composite Resin to PAEK-Based Substructure Restorative Materials.

PURPOSE: To evaluate and compare the shear bond strength (SBS) of composite veneering material to polyetherketoneketone (PEKK), polyetheretherketone (PEEK), zirconia (YZ), and nickel-chromium alloy (NiCr) substructure restorative materials. MATERIALS AND METHODS: Forty samples (12 × 2 mm) were prepared from four materials: PEKK, PEEK, zirconia, and NiCr alloy (n = 10). The Vickers hardness was evaluated before preparing the surface for bonding by shot-blasting using 110 µm Al2 O3 particles. The surface roughness (Ra) of each sample was determined using a noncontact optical profilometer. The veneering resin was bonded onto each sample following primer application. The prepared samples were then subjected to an SBS test using a universal testing machine at 0.5 mm/min crosshead speed. Failure modes and surface topography following debonding were assessed. The data were statistically analyzed using ANOVA and Tukey's post-hoc comparison test (p < 0.05).  RESULTS: The highest and lowest mean surface roughness was observed in PEEK (3.45 ±0.13 µm) and NiCr (1.87 ±0.07 µm) materials, respectively. A significant difference in roughness values was observed between the materials except for NiCr and YZ (p = 0.547). Concerning SBS, PEEK and NiCr exhibited the highest (16.23 ±0.96 MPa) and lowest (10.1 ±0.63 MPa) values. The mean difference in SBS indicated a statistically significant difference between the material groups (p < 0.01). CONCLUSIONS: PEKK materials demonstrated significantly lower SBS than PEEK and significantly higher SBS values than conventional zirconia and alloy materials. A positive and significant correlation between mean roughness and SBS was observed, but the causality could be either intrinsic to the material or the roughness.

Adhesion concepts and techniques for laboratory-processed indirect dental restorations.

The purpose of this review was to analyze the existing literature on surface conditioning of the veneering surface of substructure restorative materials in dental laboratories. New technologies are constantly improving the treatment options for fabricating dental restorations, and new materials and adhesion procedures are being offered to clinicians and dental technologists. To establish a reliable adhesion between the veneer and substructure in the dental laboratory, various surface treatment procedures and adhesion promoters are employed. The composition of a material influences the adhesion approach selected, and implementing a reliable adhesion strategy is critical for the predictability of veneered indirect dental restorations. However, surface treatment of a wide range of available material options can be challenging. Therefore, understanding various adhesion processes for different restorative materials may assist dental technologists in selecting the best and appropriate surface conditioning protocol for each dental restorative material category.

Perception of COVID-19 Booster Dose Vaccine among Healthcare Workers in India and Saudi Arabia.

Background: COVID-19 vaccines were made available to the public by the end of 2020. However, little is known about COVID-19 booster dose (CBD) vaccine perception among healthcare workers (HCW) worldwide. The present study aims to assess the perception of CBD vaccines among healthcare workers in India and Saudi Arabia (SA). Methods: A cross-sectional study was conducted among HCWs in two countries, India and SA. Data were gathered through the use of a self-administered questionnaire. A convenience sampling technique was utilized to collect the data. Results: A total of 833 HCW responses were collected from the two countries, with 530 participants from India and 303 participants from SA responding to the questionnaire. Among them, 16% from India and 33% from SA were unwilling to take a CBD (p < 0.005). The primary reasons for not being willing were concerns about whether the vaccine would be effective (32%) and concerns about probable long-term side effects (31%). Concerns about not knowing enough about the vaccination (30%) and the possibility of long-term side effects (28%) were the primary concerns in SA. Regression analysis showed that males, urban residents, and post-graduates were more willing to take the CBD. Conclusion: There is a good perception of CBD and some hesitancy in receiving the booster dose among HCWs in both countries. The introduction of personalized education, risk communication, and deliberate policy could help to reduce the number of people who are unwilling to take a booster shot.

Topographical changes and bactericidal efficacy of antimicrobial photodynamic therapy on titanium implant surface.

BACKGROUND: reExtensive rsearch has been done on various disinfection modalities used to achieve an aseptic implant surface. However, the bacterial efficacy and the topographical alterations resulting from the use of these techniques have never been compared. OBJECTIVE: This study aimed to evaluate and compare the disinfection efficacy and surface changes on a bacteria contaminated titanium block following application of various disinfectants. METHOD: Ultrasonically cleaned titanium blocks were contaminated with Porphyromonas gingivalis and Tannerella forsythia. The infected titanium implants were randomly divided into four experimental groups and decontaminated using antimicrobial photodynamic therapy (aPDT), laser therapy, chlorhexidine and hydrogen peroxide. Bacterial viability and surface changes following decontamination were analyzed. RESULT: Bacterial viability decreased in all the groups, with aPDT having the highest reduction. Surface roughness remained unchanged whereas the contact angle lessened in the aPDT group. CONCLUSION: aPDT could possibly be a suitable alternative to other disinfection regimen to treat periimplantitis.

Antimicrobial efficacy and topographical alterations of photodynamic therapy versus conventional antimicrobials on contaminated zirconia ceramic in vitro.

PURPOSE: The aim of this in vitro study was to assess the efficacy of antimicrobial photodynamic therapy (aPDT), neodymium-doped yttrium aluminium garnet (Nd:YAG) laser, and two other disinfecting agents against P. gingivalis and T. forsythia that colonized over zirconia ceramics and to evaluate if the disinfecting protocols result in zirconia surface alteration. MATERIALS AND METHODS: The experiment was conducted on pre-sintered, commercially available Yttria Stabilized Zirconia (Y-TZP) ceramic blocks. The bacterial strains of P. gingivalis and T. forsythia were used to contaminate the zirconia specimens. The infected zirconia specimens were randomly divided into 4 groups (n=20/group): aPDT, Nd:YAG laser, hydrogen peroxide (H2O2), and chlorhexidine groups. The viability of bacteria was assayed using the MTT protocol. The surface roughness (Ra) of all zirconia specimens was estimated using a profilometer and a drop-shape analyzer was used to evaluate the contact angle using a special sessile drop method. RESULTS: A statistically significant reduction by the aPDT group is noticed for P. gingivalis and T. forsythia species compared to other disinfection methods (p<0.05). The second highest reduction was seen for chlorhexidine followed by Nd:YAG laser. The least reduction was demonstrated for the hydrogen peroxide group. Statistically, there was no significant difference in Ra scores between the four groups. However, the contact angles were significantly reduced from the zirconia specimens after the aPDT method which indicates a hydrophilicity increase compared to other groups. The SFE scores of all decontamination protocols from highest to lowest were aPDT (41.68), chlorhexidine (39.83), Nd:YAG (34.52), and H2O2 (29.88). CONCLUSIONS: Antimicrobial photodynamic therapy demonstrated a high antibacterial efficacy over zirconia ceramic surface without altering surface topography.

Assessment of effect of accelerated aging on interim fixed dental materials using digital technologies.

PURPOSE: This study assessed the physical and mechanical properties of interim crown materials fabricated using various digital techniques after accelerated aging. MATERIALS AND METHODS: Three groups of interim dental restorative materials (N = 20) were tested. The first group (CO) was fabricated using a conventional manual method. The second group (ML) was prepared from prefabricated resin blocks for the milling method and cut into specimen sizes using a cutting disc. The third group (3D) was additively manufactured using a digital light-processing (DLP) 3D printer. Aging acceleration treatments using toothbrushing and thermocycling simulators were applied to half of the specimens corresponding to three years of usage in the oral environment (N = 10). Surface roughness (Ra), Vickers microhardness, 3-point bending, sorption, and solubility tests were performed. A 2-way analysis of variance (ANOVA) and Fisher's multiple comparison test were used to compare the results among the groups. RESULTS: The mean surface roughness (Ra) of the resin after accelerated aging was significantly higher in the CO and ML groups than that before aging, but not in the 3D group. All groups showed reduced hardness after accelerated aging. The flexural strength values were highest in the 3D group, followed by the ML and CO groups after accelerated aging. Accelerated aging significantly reduced water sorption in the ML group. CONCLUSION: According to the tested material and 3D printer type, both 3D-printed and milled interim restoration resins showed higher flexural strength and modulus, and lower surface roughness than those prepared by the conventional method after accelerated aging.

Fatigue behavior and damage modes of high performance poly-ether-ketone-ketone PEKK bilayered crowns.

OBJECTIVES: To evaluate and compare the fatigue behavior (fatigue limit and fatigue life) and damage modes of high-performance poly-ether-ketone-ketone (PEKK), zirconia and alloy bilayered crowns. MATERIALS AND METHODS: A total of 110 crowns (n = 50 for fatigue limit and n = 60 for fatigue life) were fabricated and used in this study. Pekkton® ivory discs, yttrium stabilized zirconia blanks and NiCr casting alloy were used to produce the respective PEKK, zirconia and alloy copings for crown fabrication. The prepared crowns were veneered with composite resin and subjected to fatigue tests. The fatigue limit was evaluated using the staircase method and the fatigue life of the samples was evaluated by subjecting the crowns to a load lower than the fatigue limit of that particular group, and also with an intermediate load of 522 N. A graphical plot was generated from the shape parameter (ß) and life parameter (α) values obtained through the Weibull analysis method. Kruskal-Wallis and Mann-Whitney tests were applied to determine the significance differences in the recorded fracture mode between the study groups. The damage modes of the samples were assessed using Burke's classification. RESULTS: The recorded fatigue limits of the groups were 442.8 ± 42.1 N, 608.7 ± 7.6 N, and 790.4 ± 29.2 N for zirconia, NiCr and PEKK, respectively. A significant difference in the fatigue limit of the groups was observed (p < 0.05). PEKK samples demonstrated the highest survival cycles of 1,170,000 and the lowest survival cycles was observed with zirconia samples at 100,000 under 522 N loading. The fracture modes in PEKK samples were largely distributed between code 1 and 2 whereas the fracture modes in NiCr group was distributed between code 1 and 4 and YZ crowns exhibited more of code 5 fractures. The difference in fracture modes among the groups was statistically significant (p < 0.05). CONCLUSION: The PEKK group demonstrated better results compared to zirconia and NiCr based crowns. The PEKK group demonstrated high fatigue limit and survived the highest fatigue life cycles among the tested groups.

Bond strength of root canal filling with radicular dentin previously treated with either photobiomodulation or photodynamic therapy: Effect of disinfection protocols.

PURPOSE: The aim of the present study was to establish an assessment regarding the efficacy of final disinfection protocols and sealers on the bond strength (BS) of root canal (RC) filling materials on root dentin which has already been treated with photobiomodulation (PBT) or photodynamic therapy (PBT) respectively. METHODS: One-hundred and twenty root canals were included in the present study. The selected teeth were cleaned and shaped to accept the obturation. The prepared specimens were subjected to laser therapy (PBT and PDT) and were randomized into three groups (n = 20/group) on the basis of irrigation technique: Group 1: distilled water (DW) + ultrasonic irrigation (UI); Group 2: 17 % EDTA; Group 3: 0.2 % Chlorhexidine digluconate (CHx) respectively. Each specific group was further divided into two subgroups (n = 10), based on endodontic sealing agent incorporated during obturation: AH Plus or MTA Fillapex. The push-out test was used to gauge the BS, whereas the evaluation was done with the help of two-way ANOVA which was followed by a subsequent Tukey post-hoc test. The chi-square test was used to calculate the mode of failure in the selected specimens (α = 5%). RESULTS: The final irrigation protocols of 17 % EDTA and CHX helped to enhance the BS of RC filling material with either sealer agent used (p < 0.05), whereas, AH Plus reported an increase in the values of BS as compared to its counterpart, MTA Fillapex (p < 0.05). Increased values of cohesive failure were associated with all the groups, irrespective of the tested final irrigation protocols and RC sealer agents (p < 0.05). There was no significant difference between the laser therapies among all the groups (p < 0.05). CONCLUSIONS: The use of 17 % EDTA and CHX and sealing material AH Plus increased the BS of the obturation on radicular dentin previously subjected to either of the mentioned laser therapies. Furthermore, no significant effect on the BS was observed with the use of lasers in the study.

Comparing the optical and mechanical properties of PEKK polymer when CAD/CAM milled and pressed using a ceramic pressing furnace.

The aim was to optimise the hot pressing parameters for processing PEKK polymer using a standard ceramic pressing furnace and compare the optical and mechanical properties of pressed samples to PEKK samples produced via CAD/CAM milling. The samples were compared using a spectrophotometer to determine the CIE L*a*b* colour values and ΔE colour difference. A universal testing machine was used for biaxial flexural strength testing and Vickers Hardness machine for measuring the hardness. It was concluded that hot pressed and milled PEKK samples showed no significant difference in the colour values, biaxial flexural strength or hardness.

Fracture resistance of zirconia-composite veneered crowns in comparison with zirconia-porcelain crowns.

The objectives were to evaluate the fracture resistance and stress concentration in zirconia/composite veneered crowns in comparison to zirconia/porcelain crowns using occlusal fracture resistance and by stress analysis using finite element analysis method. Zirconia substructures were divided into two groups based on the veneering material. A static load was applied occlusally using a ball indenter and the load to fracture was recorded in Newtons (N). The same crown design was used to create 3D crown models and evaluated using FEA. The zirconia/composite crowns subjected to static occlusal load showed comparable results to the zirconia/porcelain crowns. Zirconia/composite crowns showed higher stress on the zirconia substructure at 63.6 and 50.9 MPa on the zirconia substructure veneered with porcelain. In conclusion, zirconia/composite crowns withstood high occlusal loads similar to zirconia/porcelain crowns with no significant difference. However, the zirconia/composite crowns showed higher stress values than the zirconia/porcelain crowns at the zirconia substructure.