Crestal strain of two-implant mandibular overdentures with implants placed at different positions: An in vitro 3D printed simulation study.

STATEMENT OF PROBLEM: The 2-implant mandibular overdenture (2IMO) is a popular treatment for patients with mandibular edentulism. However, information on the influence of implant positions on crestal strain is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the crestal strain around 2 implants to support mandibular overdentures when placed at different positions. MATERIAL AND METHODS: Edentulous mandibles were 3-dimensionally (3D) designed separately with 2 holes for implant placement at similar distances of 5, 10, 15, and 20 mm from the midline, resulting in 4 study conditions. The complete denture models were 3D designed and printed from digital imaging and communications in medicine (DICOM) images after scanning the patient's denture. Two 4.3×12-mm dummy implants were placed in the preplanned holes. Two linear strain gauges were attached on the crest of the mesial and distal side of each implant (CH1, CH2, CH3, and CH4) and connected to a computer to record the electrical signals. Male LOCATOR attachments were attached, the mucosal layer simulated, and the denture picked up with pink female nylon caps. A unilateral and bilateral force of 100 N was maintained for 10 seconds for each model in a universal testing machine while recording the maximum strains in the DCS-100A KYOWA computer software program. Data were analyzed by using 1-way analysis of variance, the Tukey post hoc test, and the paired t test (α=.05). RESULTS: Under bilateral loading, the strain values indicated a trend with increasing distance between the implants with both right and left distal strain gauges (CH4 and CH1). The negative (-ve) values indicated the compressive force, and the positive (+ve) values indicated the tensile force being applied on the strain gauges. The strain values for CH4 ranged between -166.08 for the 5-mm and -251.58 for the 20-mm position; and for CH1 between -168.08 for the 5-mm and -297.83 for the 20-mm position. The remaining 2 mesial strain gauges for all 4 implant positions remained lower than for CH4 and CH1. Under unilateral-right loading, only the right-side distal strain gauge CH4 indicated the increasing trend in the strain values with -147.5 for the 5-mm, -157.17 for the 10-mm, -209.33 for the 15-mm, and -234.75 for the 20 mm position. The remaining 3 strain gauges CH3, CH2, and CH1 ranged between -28.33 and -107.17. For each position for both implants, significantly higher (P<.05) strain values were observed on the distal strain gauge channels CH4 and CH1 than on the mesial channels CH3 and CH2 under bilateral loading and on the right side under unilateral loading. CONCLUSIONS: Peri-implant crestal strains in the 2IMO increased by increasing the distance of the implants from the midline. The stress values progressively increased from 5 to 10 mm to 15 to 20 mm from midline, represented as lateral incisor, canine, and premolar positions. The distal side of the implants exhibits higher strains than the mesial side of the implants.

Stress and strain patterns of 2-implant mandibular overdentures with different positions and angulations of implants: A 3D finite element analysis study.

STATEMENT OF PROBLEM: The 2-implant mandibular overdenture is a popular treatment for the edentulous mandible, but information on optimum implant positions and/or angulations and their stress and strain patterns is lacking. PURPOSE: The purpose of this finite element analysis study was to evaluate stress and strain distribution patterns in 2-implant mandibular overdentures with different positions and angulations of implants under unilateral and bilateral loading. MATERIAL AND METHODS: A cone beam computed tomography (CBCT)-based, 3-dimensional (3D) model of the mandible and an intraoral scanning-based 3D model of the denture were developed in the Mimics software program. A 3D model of a standard-sized implant with a low-profile overdenture attachment (LOCATOR) was developed in the Solidworks software program. Two implants were inserted in the 3D model of the mandible, with implants placed at different positions, 5, 10, 15, and 20 mm from the midline, and different distal angulations, 0-5, 0-10, 0-15, 5-5, 10-10, and 15-15 degrees (at 10-mm distance), in the 3Matics software program. Unilateral and bilateral vertical loads of 100 N were applied on the first molars in the ANSYS software program to record maximum von Mises stresses and strain values. RESULTS: The stresses in the implants were maximum when placed at a 20-mm distance (4.18 MPa under unilateral and 4.2 MPa under bilateral loading), while for the implants placed at 5 mm, 10 mm, and 15 mm, the indicated stresses were less than 2.46 MPa following an increasing trend with an increase in the distance. The stresses in the implants were maximum when placed at 15-15-degree angulations (0.93 under unilateral and 0.92 MPa under bilateral loading). For lower angulations, the stresses on the implants ranged from 0.05 to 0.87 MPa. No specific trend was observed in stresses and strains with 0-5-, 0-10-, and 0-15-degree angulations, but an increasing trend was observed with 5-5-, 10-10-, and 15-15-degree angulations under unilateral loading. Under bilateral loading, the stresses and strains on the implants and the mandible showed negligible variations across all 6 angulations. CONCLUSIONS: The most posterior position of implants (20 mm) exhibited the highest stresses and strains on the implants and the mandible under both loading conditions. Implants placed with 15-15-degree angulations exhibited the highest stresses. Stresses and strains were similar in implants with lower angulations.

Correlation of implant position and crestal bone loss in 2-implant mandibular overdentures with immediate loading protocols: A prospective clinical study.

STATEMENT OF PROBLEM: The 2-implant mandibular overdenture (2IMO) is a popular treatment for patients with an edentulous mandible, but information on the effect of the optimum implant position on the peri-implant crestal bone level with immediate loading protocols is lacking. PURPOSE: The purpose of this prospective clinical study was to evaluate correlations between different implant positions and crestal bone loss and between interimplant distance and the crestal bone loss in patients with 2IMOs with immediate loading protocols at 1-year follow-up. MATERIAL AND METHODS: A total of 24 participants (13 men, 11 women, mean ±standard deviation age 63.25 ±10.76 years) were treated with 2IMOs (48 Ti-Zr implants) by a single operator between August 2015 and October 2020. The implant diameters (3.3 mm or 4.1 mm) and lengths (10 mm or 12 mm) were selected based on the crestal bone width, and the implants were placed, if possible, in the canine regions. Implant positions and interimplant distance (mm) were measured intraorally with dividers. Prefabricated mandibular dentures were immediately loaded with the LOCATOR-attachments by using a direct intraoral pickup procedure. Crestal bone-level changes were measured with a software program on the mesial and distal sides of each implant from periapical radiographs made with a paralleling technique (at baseline and 1-year follow-up). The measurement values were normalized. The Spearman rho correlation test and paired samples t tests were used for data analysis (α=.05). RESULTS: The mean ±standard deviation position of the implants from the midline was 8.78 ±2.25 mm (9.00 ±2.22 mm right side, 8.56 ±2.31 mm left side), and the mean interimplant distance was 16.94 ±4.03 mm. At 1-year follow-up, the mean ±standard deviation crestal bone loss was 0.50 ±0.47 mm (n=48) (0.57 ±0.65 mm mesial, 0.43 ±0.53 mm distal). The mean ±standard deviation crestal bone loss was 0.46 ±0.4 mm with Ø3.3-mm implants (n=42) and 0.9 ±0.8 mm with Ø4.1-mm implants (n=6) (P=.005). Implant positions were negatively correlated (rs=-0.37) with the crestal bone loss, and the correlation was significant (P=.009). Interimplant distances were also negatively correlated with crestal bone loss (rs=-0.60; P=.002). Bone loss on the mesial side was positively correlated with that on the distal side rs=0.20; however, the correlation was not significant (P=.16). CONCLUSIONS: A weak and negative correlation was found between the implant position from the midline and the crestal bone loss and also between the interimplant distance and crestal bone loss in patients provided with 2IMOs with immediate loading protocols.

Different implant diameters and their effect on stress distribution pattern in 2-implant mandibular overdentures: A 3D finite element analysis study.

STATEMENT OF PROBLEM: The edentulous mandible is commonly treated with a 2-implant overdenture. A change in diameter of the implants may affect the biomechanical behavior of the overdenture, but information on these effects is lacking. PURPOSE: The purpose of this 3D finite element analysis study was to evaluate the biomechanical behavior of 2-implant mandibular overdentures (2IMO) and their individual components by using implants of different diameters. MATERIAL AND METHODS: A 3D mandibular model was obtained from the cone beam computed tomography (CBCT) images of a 59-year-old edentulous man, and a 3D denture model was developed from intraoral scanning files in the Mimics software program. A 3D model of different diameters of implants (2.5 mm, 3.0 mm, 3.5 mm, and 4.0 mm) with a LOCATOR attachment was developed in the Solidworks software program. Two same-sized implants were inserted in the mandibular model at 10 mm from the midline in the 3Matics software program. A vertical load of 100 N was applied on the first molar region on the right side or both sides in the ANSYS software program. The maximum von Mises stresses and strains were recorded and analyzed. RESULTS: Stresses within the implants decreased with an increase in diameter (from 2.5 mm to 3 mm, 3.5 mm, and 4.0 mm) of the implants. The highest stresses were observed with 2.5-mm-diameter implants (0.949 MPa under unilateral and 0.915 MPa under bilateral loading) and the lowest with Ø4-mm implants (0.710 MPa under unilateral and 0.703 MPa under bilateral loading). The strains on the implants ranged between 0.0000056 and 0.0000097, and those on the mandible ranged between 0.0000513 and 0.0000566 across all diameters of the implants without following a specific trend. CONCLUSIONS: In 2IMO, the stresses in the implants and mandible decreased with an increase in the diameter of the implants. The implants of lesser diameter (2.5 mm) exhibited the highest stresses and strains, and the implants of the largest diameter (4 mm) exhibited the lowest stresses and strains under unilateral and bilateral loading conditions.

Validation of a 'Work Readiness Scale' for health professional (HP) graduates.

BACKGROUND: There is a continuing concern about how graduate work readiness (WR) reflects on the success of universities meeting the requirements of employment. This study is to establish a valid and reliable instrument measuring WR in health professions (HP) graduates of medicine, pharmacy and dentistry. METHODS: The study from March 2016 to April 2017 was conducted to validate the 'Work Readiness Scale' (WRS; Deakin University) using Principal Component Analysis and Cronbach - α for internal consistency. It was modified to a four-item even-point scale and distributed as an online survey to 335 final year students of the three programs. RESULTS: A reduction from 64 to 53 items provided good internal consistency in all factors: WC 0.85, OA 0.88, SI 0.88 and PC 0.71. The PC domain had the greatest item reduction from 22 to 6, whilst the SI domain increased in items from 8 to 19. These changes may be associated with difference in understanding or interpretation of the items in the SI domain. CONCLUSION: The modified WRS can be used to evaluate job readiness in HP graduates. However, it needs further refinement and validation in specific educational and employment contexts.

Biomechanical behavior of mandibular overdenture retained by two standard implants or 2 mini implants: A 3-dimensional finite element analysis.

STATEMENT OF PROBLEM: Mini implants (<3 mm in diameter) are being used as an alternative to standard implants for implant-retained mandibular overdentures; however, they may exhibit higher stresses at the crestal level. PURPOSE: The purpose of this finite element analysis study was to evaluate the biomechanical behavior (stress distribution pattern) in the mandibular overdenture, mucosa, bone, and implants when retained with 2 standard implants or 2 mini implants under unilateral or bilateral loading conditions. MATERIAL AND METHODS: A patient with edentulous mandible and his denture was scanned with cone beam computed tomography (CBCT), and a 3D mandibular model was created in the Mimics software program by using the CBCT digital imaging and communications in medicine (DICOM) images. The model was transferred to the 3Matics software program to form a 2-mm-thick mucosal layer and to assemble the denture DICOM file. A 12-mm-long standard implant (Ø3.5 mm) and a mini dental implant (Ø2.5 mm) along with the LOCATOR male attachments (height 4 mm) were designed by using the SOLIDWORKS software program. Two standard or 2 mini implants in the canine region were embedded separately in the 3D assembled model. The base of the mandible was fixed, and vertical compressive loads of 100 N were applied unilaterally and bilaterally in the first molar region. The material properties for acrylic resin (denture), titanium (implants), mucosa (tissue), and bone (mandible) were allocated. Maximum von Mises stress and strain values were obtained and analyzed. RESULTS: Maximum stresses of 9.78 MPa (bilaterally) and 11.98 MPa (unilaterally) were observed in 2 mini implants as compared with 3.12 MPa (bilaterally) and 3.81 MPa (unilaterally) in 2 standard implants. The stress values in the mandible were observed to be almost double the mini implants as compared with the standard implants. The stresses in the denture were in the range of 3.21 MPa and 3.83 MPa and in the mucosa of 0.68 MPa and 0.7 MPa for 2 implants under unilateral and bilateral loading conditions. The strain values shown similar trends with both implant types under bilateral and unilateral loading. CONCLUSIONS: Two mini implants generated an average of 68.15% more stress than standard implants. The 2 standard implant-retained overdenture showed less stress concentration in and around implants than mini implant-retained overdentures.

Molecular Dynamic Simulation Search for Possible Amphiphilic Drug Discovery for Covid-19.

To determine whether quaternary ammonium (k21) binds to Severe Acute Respiratory Syndrome-Coronavirus 2 (SARS-CoV-2) spike protein via computational molecular docking simulations, the crystal structure of the SARS-CoV-2 spike receptor-binding domain complexed with ACE-2 (PDB ID: 6LZG) was downloaded from RCSB PD and prepared using Schrodinger 2019-4. The entry of SARS-CoV-2 inside humans is through lung tissues with a pH of 7.38-7.42. A two-dimensional structure of k-21 was drawn using the 2D-sketcher of Maestro 12.2 and trimmed of C18 alkyl chains from all four arms with the assumption that the core moiety k-21 was without C18. The immunogenic potential of k21/QA was conducted using the C-ImmSim server for a position-specific scoring matrix analyzing the human host immune system response. Therapeutic probability was shown using prediction models with negative and positive control drugs. Negative scores show that the binding of a quaternary ammonium compound with the spike protein's binding site is favorable. The drug molecule has a large Root Mean Square Deviation fluctuation due to the less complex geometry of the drug molecule, which is suggestive of a profound impact on the regular geometry of a viral protein. There is high concentration of Immunoglobulin M/Immunoglobulin G, which is concomitant of virus reduction. The proposed drug formulation based on quaternary ammonium to characterize affinity to the SARS-CoV-2 spike protein using simulation and computational immunological methods has shown promising findings.

Unsplinted Attachment Systems and Peri-implant Outcomes in Two-implant-retained Mandibular Overdentures: A Systematic Review of Randomized Controlled Trials.

AIM: The purpose of this review is to compare randomized clinical trials evaluating the peri-implant tissue outcomes using different unsplinted attachment systems in two implant-retained mandibular overdentures. BACKGROUND: Literature lacks information on various unsplinted attachment systems and their effect on peri-implant tissue health. A focus question (as per PICOS) was set as follows: Does one particular unsplinted attachment system (I) compared with another (C) results in better peri-implant outcomes (O) in two implant-retained mandibular overdentures (P) using randomized controlled trials (RCTs) (S)? The literature search was conducted in the PubMed, MEDLINE and Cochrane Central Register of Controlled Trials (CENTRAL) databases between January 2011 and December 2021. The keywords used were "denture, overlay," "denture," "overlay" AND "dental prosthesis, implant supported," "dental implants," "dental implant abutment design" AND "jaw, edentulous," "mouth, edentulous" AND "mandible." Only RCTs on two implant-retained mandibular overdentures using unsplinted attachment systems measuring peri-implant tissue outcomes with minimum 1-year follow-up were selected. In total, 224 studies were identified in initial search, and 25 were shortlisted for full-text evaluation. Four studies were included for systematic review upon considering inclusion and exclusion criteria. The risk of bias was evaluated using Cochrane Risk of Bias Tool 2.0 (RoB 2.0). REVIEW RESULTS: A total of 41 patients received ball attachments (in 3 studies), 36 patients received low-profile attachments (in 3 studies), 16 patients received magnet attachments (in 1 study), and 13 patients received telescopic attachments (in 1 study). All four studies used standard sized implants, however, differed in implant manufacturers. Two studies which compared ball attachments low-profile attachments revealed-similar peri-implant tissue health parameters but differed in crestal bone-level changes. One study compared ball with telescopic attachments and revealed similar results in crestal bone-level changes and all four peri-implant tissue health parameters. Single study compared magnets with low-profile attachments and shown lesser bone loss with magnet attachments. Single study was judged to have low risk of bias, single with some concerns, and remaining two to have high risk of bias. CONCLUSION: Gingival index and bleeding index of the patients were not influenced by any of the unsplinted overdenture attachment (stud, magnet, telescopic) system. Inconclusive results found among the studies evaluated comparing crestal bone loss and plaque index. CLINICAL SIGNIFICANCE: This review manuscript has simplified comparative analysis of different unsplinted attachment systems used in two implant mandibular overdentures to help clinicians choose correct system in such situation.

Crestal bone-level changes and patient satisfaction with mandibular overdentures retained by one or two implants with immediate loading protocols: A randomized controlled clinical study.

STATEMENT OF PROBLEM: Single-implant-retained overdentures are an alternative treatment option for an edentulous mandible. However, evaluation of their clinical performance with an immediate loading protocol is lacking. PURPOSE: The purpose of this prospective randomized controlled clinical study was to evaluate crest bone-level changes and patient satisfaction with mandibular overdentures retained by 1 or 2 titanium-zirconium (Ti-Zr) implants with immediate loading protocols after 1 year. MATERIAL AND METHODS: Thirty-six Ti-Zr implants were placed in 24 participants (single central implant in 12 participants and 2 interforaminal implants in 11 participants) by a single operator. LOCATOR attachments were used to retain the mandibular overdentures with an immediate loading protocol, and observations were made at 1 month and 1 year. Changes to the crestal bone level were evaluated with digital periapical radiographs. A 100-mm visual analog scale (VAS) was used to evaluate patient satisfaction. The Mann-Whitney U test was used to analyze the data. RESULTS: At 1 month, the mean crestal bone loss was 0.23 mm in the 2-implant group (n=22) and 0.39 mm (P=.181) in the single-implant group (n=11). At 1 year, the bone loss was 0.67 mm in the 2-implant group and 0.88 mm (P=.248) in the single-implant group. The mean VAS score for patient satisfaction level increased from 38.3% to 49.7% for single-implant participants and from 40.5% to 54.8% for 2-implant participants 1 month after implant placement (P=.250) and from 38.3% to 54.5% for single-implant participants and from 40.5% to 58.9% for 2-implant participants after 1 year (P=.341). CONCLUSIONS: Single-implant-retained mandibular overdentures with an immediate loading protocol may represent a viable treatment option considering crestal bone-level changes and patient satisfaction compared with 2-implant-retained mandibular overdentures after 1 year of follow-up.

Pivoting Dental Practice Management during the COVID-19 Pandemic-A Systematic Review.

Background and Objectives: The aims of this systematic review were to identify additional infection control measures implemented in dental practice globally to prevent cross-infection and evaluate the psychological impacts of the pandemic among dental professionals. Materials and Methods: A sequential systematic literature search was conducted from December 2019 to 30 April 2020 through PubMed, CINAHL, Scopus, Google Scholar, Embase, and Web of Science databases. The search yielded the following results: "COVID-19" (n = 12,137), "Novel corona virus" (n = 63), "COVID-19 and dentistry" (n = 46), "COVID-19 and oral health" (n = 41), "Novel Corona virus and Dentistry" (n = 0), "dental health and Novel Coronavirus" (n = 26), and "dental practice and Novel Coronavirus" (n = 6). Results: After a careful review and eliminating articles based on inclusion and exclusion criteria, the final review included 13 articles. Management of infection control is discussed extensively in the literature and remains the main theme of many Coronavirus Disease 2019 (COVID-19) articles on dentistry. Telephone triage using a questionnaire, hand hygiene, personal protective equipment (PPE) for clinical and nonclinical staff, a preprocedural mouth rinse, and aerosol management have been discussed and implemented in few countries. Three studies recommended that elective treatments for patients with a temperature of >100.4 F or 38 °C should be postponed or performed in an airborne infection isolation room (AIIR) or negative-pressure room. Limiting the number of patients in the waiting area, the removal of shared objects, proper ventilation, and physical distancing were highly recommended. Psychological distress among dental professionals in relation to existing medical conditions and self-efficacy has been discussed. Conclusions: Although the COVID-19 pandemic has had a substantial impact on the dental profession worldwide, our review highlights many practice management approaches to adopt the new norm. More research highlighting evidence-based safety practices and multisectoral collaboration is required to help dental professionals make informed decisions and make the profession safe, both for the patient and dental professionals.

Factors associated with faculty participation in research activities in dental schools.

BACKGROUND: To quantify participation in dental research activities in Malaysia, and investigate its association with socio-demographic and professional characteristics, and perceptions of research and development (R&D) culture. MATERIALS AND METHODS: Dental academics in Malaysian dental schools were invited to complete a questionnaire by email and post. The survey comprised questions on research activities in the past 12 months, socio-demographic and professional characteristics, and the R&D Culture Index. Principal components factor analysis was carried out to confirm the factor structure of the R&D Culture Index. Chi-square test was used to identify association of research activities with R&D culture, and socio-demographic and professional characteristics. Binary logistic regression was carried to identify predicators of research activities. RESULTS: Of 256 potential participants contacted, 128 (50%) useable responses were returned. Three R&D Culture factors accounting for 57.4% of variance were extracted. More positive perception of R&D Support was associated with Malaysians (0.025) and those employed in Government schools (0.017). R&D Skills and Aptitude were associated with older respondents (0.050), PhD qualification (0.014) and more years in academia (0.014). R&D Intention was associated with any of the socio-demographic characteristics. Thirty (23.4%) respondents reported a peer-review research publication in the past 12 months, which was associated with having a PhD (OR 12.79, CI 1.28-127.96), after adjustment in regression analyses. DISCUSSION: Postgraduate research training should be encouraged to promote participation in research activities. R&D culture did not appear to impact on research productivity. Other factors such as individual attitudinal interests should be studied.

Antimicrobial FiteBac® K21 promotes antimicrobial Potency and wound healing.

Objectives: Successful root canal therapy is dependent on the efficacy of complete instrumentation and adequate use of chemical irrigant to eliminate the biofilm from dentin surface. The aim of the study was to examine antibiofilm and antimicrobial effectiveness of newly formulated Quaternary ammonium silane (QAS/also codenamed K21; against Fusobacterium nucleatum (F. nucleatum) and Enterococcus faecalis (E. faecalis) biofilm on radicular dentin with evaluation of the anti-inflammatory consequence in vivo. Methods: Fourier Transform Infrared Spectroscopy (FTIR) was performed after complete hydrolysis of K21 solution. Human teeth were inoculated with biofilms for 7-days followed by treatment with various irrigants. The irrigant groups were Sodium hypochlorite [NaOCl (6%)], Chlorhexidine [CHX (2%)], K21 (0.5%), K21 (1%) and Saline. Scanning electron microscopy (SEM) was performed for biofilm and resin-dentin penetration. Transmission Electron Microscopy (TEM) of biofilms was done to evaluate application of K21. For in vivo evaluation, Albino wistar rats were injected subcutaneously and sections were stained with haematoxylin/eosin. Macrophage, M1/M2 expression were evaluated along with molecular simulation. Raman measurements were done on dried biofilms. Results: FTIR K21 specimens demonstrated presence of ethanol/silanol groups. Raman band at 1359 cm-1 resemble to -CH2- wagging displaying 29Si atoms in Nuclear Magnetic Resonance (NMR). 0.5%K21 showed cells exhibiting folded membranes. SEM showed staggering amount of resin tags with 0.5% K21 group. TEM showed membrane disruption in K21-groups. K21 groups were initially irritant, which subsided completely afterwards showing increased CD68. K21 and MMP/collagen complex was thermodynamically favourable. Conclusion: K21 root canal irrigant was able to penetrate bacterial wall and can serve as a potential irrigant for therapeutic benefits. Expression of M2 polarized subsets showed K21 can serve in resolving inflammation and potentiate tissue repair.

Unsplinted Attachments and Patient-Reported Outcome Measures (PROMs) in 2-Implant-Retained Mandibular Overdentures: A Systematic Review.

Introduction: The purpose of this review is to compare randomized clinical trials evaluating the patient-reported outcome measures (PROMs) using different unsplinted attachment systems in 2-implant-retained mandibular overdentures (2IRMODs). A focus question (as per PICOS) was set as follows: does one particular unsplinted attachment system (I) compared with another (C) result in better patient-reported outcomes (O) in two-implant-retained mandibular overdentures (P) using randomized controlled trials (S)? Materials and Methods: A literature search was conducted in the PubMed MEDLINE and Cochrane Central Register of Controlled Trials (CENTRAL) databases between November 2010 and October 2020. Only randomized controlled trials (RCTs) on 2IRMOD using unsplinted attachment systems measuring patient-centered outcomes were selected. A total of 171 studies were identified in initial search, and 27 studies were shortlisted for full-text evaluation. A total of 5 studies were included for a systematic review. The risk of bias was evaluated using Cochrane Risk of Bias Tool 2.0 (RoB 2.0). Meta-analysis could not be performed as different studies evaluated different patient-reported outcomes, namely, satisfaction, quality of life, complications, preferences, or combinations of these. Results: A total of 23 patients received low-profile (self-aligning) attachments (in 2 studies), 69 patients received standard ball attachments (in 5 studies), 25 patients received telescopic (or conus) attachments (in 2 studies), and 20 patients received mini-ball attachments (in 1 study). Two studies compared ball attachments and low-profile attachments and revealed similar satisfaction and quality of life (QoL). Two studies compared ball attachments with telescopic attachments and revealed less patient satisfaction in telescopic attachments. A single study compared mini-ball attachments with standard ball attachments and showed no difference in patient-reported outcomes. Three studies were found to have a low risk of bias, and the remaining two studies had a high risk of bias. Conclusions: The standard ball, mini-ball, and low-profile attachments have no influence on PROMs in the normal interarch space. Inconclusive results were found in studies that evaluated PROMs using ball attachments versus telescopic attachments.

Effect of Implant Positions and Angulations on Retentive Strength of 2-Implant Mandibular Overdentures: An In Vitro Study with the New 3D-Printed Simulation Method.

Objectives: To evaluate the retentive strength of overdenture attachments in 2-implant mandibular overdenture (2IMO) with implants placed at different positions and angulations. Materials and Methods: Edentulous mandibular models were 3D-printed using CBCT images and Materialise Mimics software and the denture models using the intraoral scanner. Two standard implants were placed parallel at different positions from midline (5, 10, 15, and 20 mm) with 0-0 degree angulations and with different distal angulations (0-5, 0-10, 0-15, 5-5, 10-10, and 15-15 degrees) at 10±mm from midline representing 10 study groups. Low-profile male attachments were attached to the implants and the female pink attachments were picked up in the denture. A total of 4 simulated overdenture model sets for each of the 10 study groups were subjected to the universal testing machine thrice to measure a peak load (N) to disengage the attachments vertically. Data were analyzed using one-way ANOVA and Tukey's post hoc test at 0.05 significance level. Results: Varying implant positions had a statistically significant effect on the retentive strengths of the attachments (F = 5.61, P = 0.002). Peak load-to-dislodgement values (in increasing order) were 49.64 ± 8.27 N for 5 mm, 53.26 ± 11.48 N for 10 mm, 60.24 ± 12.31 N for 15 mm, and 64.80 ± 6.78 N for 20 mm groups. The retentive strength of the 20 mm group was significantly higher than 5 mm (P = 0.003) and 10 mm (P = 0.03) groups. Varying implant angulations had a significant effect on the retentive strengths of the attachments (F = 7.412, P = 0.000). The peak load-to-dislodgement values (in increasing order) were 48.20 ± 15.59 N for 5-5 degrees, 53.26 ± 11.48 N for 0-0 degrees, 54.96 ± 8.25 N for 0-5 degrees, 57.71 ± 7.62 N for 10-10 degrees, 66.00 ± 17.54 N for 15-15 degrees, 66.18 ± 14.09 N for 0-10 degrees, and 77.38 ± 10.33 N for 0-15 degrees. Retentive strength of 0-15 degrees was significantly (P < 0.05) higher than those of 0-0, 0-5, 5-5, and 10-10 degrees and that of 5-5 degrees was significantly (P < 0.05) lower than those of 0-10, 0-15, and 15-15 groups. Conclusions: Retentive strength of the 2IMO increased with increase in distance of implants from midline and increased with increase in distal angulations.

Synthesis and Incorporation of Quaternary Ammonium Silane Antimicrobial into Self-Crosslinked Type I Collagen Scaffold: A Hybrid Formulation for 3D Printing.

Novel 3D-biomaterial scaffold is constructed having a combination of a new quaternary ammonium silane (k21) antimicrobial impregnated in 3D collagen printed scaffolds cross linked with Riboflavin in presence of d-alpha-tocopheryl poly(ethyleneglycol)-1000-succinate. Groups of "0.1% and 0.2% k21", and "0.1% and 0.2% Chlorhexidine (CHX)" are prepared. k21/CHX with neutralized collagen is printed with BioX. Riboflavin is photo-activated and examined using epifluorescence for Aggregatibacter actinomycetemcomitans (7-days). Collagen is examined using TEM and measured for porosity, and shape-fitting. Raman and tandem mass/solid-state are performed with molecular-docking and circular-dichroism. X-ray diffractions, rheological tests, contact angle, and ninhydrin assay are conducted. k21 samples demonstrated collagen aggregates while 0.1% CHX and 0.2% CHX showed irregularities. Porosity of control and "0.1% and 0.2% k21" scaffolds show no differences. Low contact angle, improved elastic-modulus, rigidity, and smaller strain in k21 groups are seen. Bacteria are reduced and strong organic intensities are seen in k21 scaffolds. Simulation shows hydrophobicity/electrostatic interaction. Crosslinking is observed in 0.2% CHX/79% and 0.2% k21/80%. Circular dichroism for k21 are suggestive of triple helix. XRD patterns appear at d = 5.97, 3.03, 2.78, 2.1, and 2.90 A°. 3D-printing of collagen impregnated with quaternary ammonium silane produces a promising scaffold with antimicrobial potency and structural stability.

Biochemical changes and macrophage polarization of a silane-based endodontic irrigant in an animal model.

Silane-based/fully hydrolyzed, endodontic irrigant exhibiting antimicrobial properties, is prepared, and is hypothesized to control macrophage polarization for tissue repair. Albino wistar rats were injected with 0.1 ml root canal irrigant, and bone marrow cells procured. Cellular mitochondria were stained with MitoTracker green along with Transmission Electron Microscopy (TEM) performed for macrophage extracellular vesicle. Bone marrow stromal cells (BMSCs) were induced for M1 and M2 polarization and Raman spectroscopy with scratch assay performed. Cell counting was used to measure cytotoxicity, and fluorescence microscopy performed for CD163. Scanning Electron Microscopy (SEM) was used to investigate interaction of irrigants with Enterococcus faecalis. K21 specimens exhibited reduction in epithelium thickness and more mitochondrial mass. EVs showed differences between all groups with decrease and increase in IL-6 and IL-10 respectively. 0.5%k21 enhanced wound healing with more fibroblastic growth inside scratch analysis along with increased inflammation-related genes (ICAM-1, CXCL10, CXCL11, VCAM-1, CCL2, and CXCL8; tissue remodelling-related genes, collagen 1, EGFR and TIMP-2 in q-PCR analysis. Sharp bands at 1643 cm-1 existed in all with variable intensities. 0.5%k21 had a survival rate of BMSCs comparable to control group. Bacteria treated with 0.5%k21/1%k21, displayed damage. Antimicrobial and reparative efficacy of k21 disinfectant is a proof of concept for enhanced killing of bacteria across root dentin acquiring functional type M2 polarization for ethnopharmacological effects.

Development of an Online Asynchronous Clinical Learning Resource ("Ask the Expert") in Dental Education to Promote Personalized Learning.

This article describes the development and testing of an online asynchronous clinical learning resource named "Ask the Expert" to enhance clinical learning in dentistry. After the resource development, dental students from years 3 and 4 were randomly allocated to two groups (Group A-"Ask the Expert" and L-"lecturer-led"). All the students attempted a pre-test related to replacement of teeth in the anterior aesthetic zone. Group A (33 students) underwent an online case-based learning session of 60 minutes' duration without a facilitator, while Group L (27 students) concurrently underwent a case-based learning session of 60 minutes' duration with a lecturer facilitating the session. An immediate post-test was conducted followed by a retention test after one week. Student feedback was obtained. There was a significant increase in the test scores (maximum score 10) for both groups when comparing the pre-test (Group A-5.61 ± 1.34, Group L-5.22 ± 1.57) and immediate post-test scores (Group A-7.42 ± 1.34, Group L-8.04 ± 1.22; paired t-test, p < 0.001). However, no significant difference was observed in the test scores when comparing Group A to Group L for both the immediate post-test as well as the retention test (Group A-5.36 ± 1.29, Group L-5.33 ± 1.39 (independent sample t-test, p > 0.05). To conclude, adequately structured online asynchronous learning resources are comparable in their effectiveness to online synchronous learning in the undergraduate dental curriculum.

Oral health-related quality of life of patients using single or two-implant mandibular overdentures with immediate loading protocols: A randomized controlled trial.

Aim: Single implant-retained mandibular overdentures (1IMO) is a viable alternative to 2 implant-retained overdentures (2IMO) in edentulous patients. However, literature lacks in the quality of life (QoL) of these patients when treated with immediate loading protocols. The purpose of this study was to compare oral health-related QoL (OHRQoL) of patients using 1IMO or 2 IMO with immediate loading protocols at 1 month and 1 year. Settings and Design: Randomized Controlled Trial. Materials and Methods: Fifty-two edentulous participants treated with mandibular overdentures using either single implant (n = 26) or two implants (n = 26) with immediate loading protocol by a single operator. The low-profile stud-attachments (LOCATOR; Zest Anchors) were attached to the implants and female attachments were picked up within 0-7 days of implant placement. The OHRQoL was recorded using Oral Health Impact Profile-14 (OHIP-14) questionnaire either in English or in the Malay language before treatment and 1 month and 1 year after treatment. Statistical Analysis Used: Kruskal Wallis test was used to find out significant difference amongst 3 timepoints and 7 OHIP-14 domains and Mann-Whitney-U test to compare 1IMO or 2IMO groups. Results: Compared to baseline OHIP-14 scores, participants had a statistically significant decrease in total OHIP-14 at 1 month and 1 year after-treatment time points in both 1IMO and 2IMO groups (P < 0.05). The difference between 1 month and 1 year after-treatment total and subscale scores were also found to be statistically significant (P < 0.05). The overall QoL improvement was comparatively higher in 2IMO group than 1IMO group. The OHIP-14 scores were statistically different within seven domains (P < 0.05). Overall total scores between 1IMO and 2IMO groups were also found to be statistically significant (P < 0.05) at baseline and insignificant (P > 0.05) at 1 month and 1 year. Conclusions: Mandibular single and 2IMO improve the QoL of elderly edentulous Malaysian participants at 1 month of immediate loading and 1 year of recall. 1IMO may provide comparable QoL with the elderly patients using 2 implants.

Antimicrobial and self-crosslinking potential of experimentally developed dioctadecyldimethyl ammonium bromide and riboflavin dentin adhesive.

The aim of the study is to investigate a new formulation, based on dioctadecyldimethyl ammonium-bromide (QA) and riboflavin (RF), combining antimicrobial activities and protease inhibitory properties with collagen crosslinking without interference to bonding capabilities in a rabbit model. Quaternary ammonium riboflavin (QARF) experimental adhesives modified with dioctadecyldimethyl ammonium-bromide and riboflavin were bonded (0.5/1.0/2.0%) to rabbit dentin to investigate for pulpal-histology, interfacial-morphology, transmission electron microscopy, mechanical properties, collagen crosslinking, micro-Raman analysis, antimicrobial, and anti-protease activities. Collagen type-I molecules were generated using molecular-docking. Odontoblasts appeared with normal histology, were seen in controls with no inflammatory cells detected in 0.5% specimens at day 7 and mild inflammatory response at day 30. In QARF 2.0%, inflammatory cells were not detected at day 7 and 30 (p < .05). Dentinal tubules are seen with intact collagen surface in 1% specimens. Resin penetrated inside 1% adhesive specimens with few irregularly funnel-shaped tags. Transmission electron microscopy showed thinner collagen in all specimens except 1% QARF specimens. Biofilms were influenced by QARF adhesives. Elastic moduli were significantly higher in 1.0% and 2.0% QARF adhesive specimens with a significant increase in total crosslinks. Stable amide groups with anti-protease activity was observed in QARF groups. Charged residues were seen in the triple helix hCOL3A1, Gly489-Gly510 after stabilisation with formulation. The 1% QARF modified adhesives improved biochemical and biomechanical properties of rabbit dentin.

Guidelines for innovation in dental education during the coronavirus disease 2019 pandemic.

During the current coronavirus disease 2019 (COVID-19) pandemic, dental education and training requiring face-to-face interaction must prioritize infection prevention and the safety of students, staff, and patients. In July 2020, the Association for Dental Education, Asia Pacific (ADEAP) published safety guidelines for safe dental education during the COVID-19 pandemic. These guidelines summarize ADEAP recommendations for classroom-based courses, reopening of simulated training courses and dental clinics, and provision of clinical skills training courses in dentistry during the COIVID-19 pandemic. They have been formulated to ensure the safety of students and teaching staff, dental auxiliary staff, and patients. However, the present guidelines are considered appropriate only when the number of COVID-19 epidemic cases has been significantly reduced, i.e. when the epidemiological curve has flattened in the area concerned. The criteria for lifting restrictions on activities should be consistent with relevant jurisdictional guidelines.