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Jihad Saade,1 Hasan Skienhe,1 Hani F Ounsi,2 Jukka P Matinlinna,3 Ziad Salameh4 1Department of Prosthodontics, Faculty of Dental Medicine, Lebanese University, Beirut, Lebanon; 2Department of Restorative Dentistry and Endodontics, Faculty of Dental Medicine, Lebanese University, Beirut, Lebanon; 3Department of Restorative Dentistry and Endodontics, Faculty of Dental Medicine, Siena University, Siena, Italy; 4Department of Dental Materials Science, Faculty of Dentistry, University of Hong Kong, Pokfulam, Hong KongCorrespondence: Jihad SaadeFaculty of Dental Medicine, Lebanese University, Beirut, LebanonTel +961 3 763 404Email jihadsaade00@gmail.comPurpose: The purpose of this study was to evaluate the effect of surface treatments on zirconia-resin bonding and the effect of aging on bond durability for one year.Method: Three hundred and twenty zirconia blocks were divided into 4 equal study groups. Group 1 (control): as-sintered, group 2: (GB): grit-blasted, group 3: (LAS): laser-etched, group 4: (SIE): selective infiltration etching. Composite cylinders were bonded to the zirconia with resin cement and ceramic primer. Aging was performed following 3 different aging protocols: thermocycling, storage in distilled water, or storage in an enzymatic esterase solution. Micro-shear bond strength test (μSBS) was recorded using a universal testing machine. μSBS values were analyzed using two-way Analysis of Variance followed by Tukey post-hoc tests. Level of significance was set at 0.05.Results: GB, LAS and SIE groups showed significantly higher values when compared to control. Groups GB, LAS and SIE reported a significant decrease up to 50% in μSBS after water storage and enzymatic degradation, while control group reported a 90% decrease. Failure analysis showed mainly adhesive failure for control group, while the percentage of cohesive failure in resin cement was higher in SIE group compared to GB and LAS groups.Conclusion: Water aging and esterase solutions played a significant role by increasing bond degradation. A minimum of one-year water and esterase storage medium should be used to evaluate the durability of the bond between resin cement and zirconia.Keywords: air abrasion, laser, MDP primer, resin cement, aging

Jihad Saade,1 Hasan Skienhe,2 Hani Ounsi,3 Jukka P Matinlinna,4 Ziad Salameh51Faculty of Dental Medicine, Lebanese University, Beirut, Lebanon; 2Department of Prosthodontics, Faculty of Dental Medicine, Lebanese University, Beirut, Lebanon; 3Department of Restorative Dentistry and Endodontics, Faculty of Dental Medicine, Lebanese University, Beirut, Lebanon; 4Dental Materials Science, Faculty of Dentistry, University of Hong Kong, Sai Ying Pun, Hong Kong; 5Research Center, Faculty of Dental Medicine, Lebanese University, Beirut, LebanonPurpose: The purpose of this laboratory study was to evaluate the effect of different surface treatment combinations on resin zirconia bonding.Materials and methods: One hundred and five pre-sintered zirconia quadrangles were prepared out of zirconia blocks, polished, then sintered and divided into five groups (n=21). Group I (control): samples were untreated, group II: grit-blasting with 50 μm alumina particles, group III: grit-blasting with 100 μm alumina particles, group IV: Er,Cr:YSGG laser, and group V: selective infiltration etching technique. Microstructural analysis was performed using scanning electron microscopy, atomic force microscopy, a diffractometer, and a profilometer. Cylinders of composite resin were luted with Panavia resin composite cementand Clearfil ceramic primer. Shear bond strength (SBS) was determined using a universal testing machine.Results: SBS results were analyzed using one-way ANOVA followed by Tukey post hoc tests for multiple comparisons. The level of significance was set to 0.05. SBS values of the studied groups II, III, IV, and V were 16.2±1.8 MPa, 15.7±3.7 MPa, 14.8±3.4 MPa, and 16.8±3.0 MPa, respectively. All values were significantly higher than the control group (10.48±1.80 MPa), but without a significant difference between them. Group III exhibited the roughest surface, and Group I had a more significantly reduced surface roughness value than any other group. Group III presented the highest significant increase of tetragonal to monoclinic phase transformation (13%).Conclusion: The use of grit-blasting with greater particles size enhanced SBS with resin composite cement, but induced a higher amount of monoclinic phase transformation. The use of primer based on adhesive monomer with the resin cement is required to enhance the bonding efficiency. The use of laser enhanced the surface roughness and the bonding ability to zirconia.Keywords: air abrasion, laser, MDP primer, resin cement

The study aimed to investigate the influence of H 2 O 2 -based and H 2 O 2 -free in-office bleaching on the surface and mechanical attributes of CAD/CAM composite blocks. CAD/CAM composite blocks from five different composite materials (CC1, CC2, CC3, CC4, and CC5) were randomly divided into two groups according to bleaching application (H 2 O 2 -based and H 2 O 2 -free). The surface topography, morphology, nanohardness, elastic modulus, flexural strength, and fracture toughness were measured. A paired and unpaired sample t-tests gauged the effect of pre- and post-bleaching on the substrates. The estimated mean differences (before-after bleaching) suggested an increase in surface roughness for two materials CC2 and CC4, and a significant decrease in nanohardness for material CC4 and in elastic modulus for materials CC2 and CC4 with H 2 O 2 -based bleaching, whereas H 2 O 2 -free bleaching resulted in changes compatible with no change in these properties. Flexural strength and fracture toughness showed no evidence of changes, irrespective of the bleaching gel used. Scanning electron microscopic analysis revealed erosive effects and micropore formation due to H 2 O 2 -based bleaching. H 2 O 2 -based bleaching deteriorates the surface of CAD/CAM composite materials while H 2 O 2 -free bleaching gel had an insignificant effect on both surface and bulk properties. The clinician should carefully evaluate the potential effects of H 2 O 2 -based bleaching on the surface properties of CAD/CAM composites., (© 2024 Scandinavian Division of the International Association for Dental Research. Published by John Wiley & Sons Ltd.)

This study aims to investigate whether toothbrushes with fluoride-infused bristles have any (re)mineralisation effects on bovine enamel. Bovine incisors (N = 160) were extracted, and the buccal side of the crown was cut into dimensions of ~5 mm × 5 mm with a low-speed saw. These specimens were randomly allocated into four groups: half (80 teeth) were stored in demineralising solution (DM), and the other half were stored in deionised water (DW) for 96 h. Then, they were brushed with a force of 2.0 ± 0.1 N for five min with a manual toothbrush with either fluoride-infused (TF) or regular (TR) bristles. Microhardness (Vickers), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) were used to investigate the surfaces of the bovine enamel specimens before and after brushing. Two-way ANOVA was used to analyse the hardness data, and the pairwise comparison method was used to analyse the Ca/P ratio, for each group at α = 0.05. The results show that brushing with either of these toothbrushes increased the Vickers microhardness on DM and DW enamel ( p < 0.001), whereas hydroxyapatite was revealed in all groups by XRD. The DM samples showed a significant increase ( p < 0.05) in the Ca/P ratios after brushing with TR and TF. Conversely, under DW conditions, these ratios decreased significantly after brushing. In terms of the F atomic%, TF increased significantly. SEM revealed mineral deposition in the DM groups after toothbrushing. To conclude, toothbrushing effectively induces the microhardness of sound and demineralised enamel, while fluoride-infused bristles might be able to retain fluoride on the enamel surface.

This study aims to develop multi-functional bio-safe dental resin composites with capabilities for mineralization, high in vitro biocompatibility, and anti-biofilm properties. To address this issue, experimental resin composites consisting of UDMA/TEGDMA-based dental resins and low quantities (1.9, 3.8, and 7.7 vol%) of 45S5 bioactive glass (BAG) particles were developed. To evaluate cellular responses of resin composites, MC3T3-E1 cells were (1) exposed to the original composites extracts, (2) cultured directly on the freshly cured resin composites, or (3) cultured on preconditioned composites that have been soaked in deionized water (DI water), a cell culture medium (MEM), or a simple HEPES-containing artificial remineralization promotion (SHARP) solution for 14 days. Cell adhesion, cell viability, and cell differentiation were, respectively, assessed. In addition, the anti-biofilm properties of BAG-loaded resin composites regarding bacterial viability, biofilm thickness, and biofilm morphology, were assessed for the first time. In vitro biological results demonstrated that cell metabolic activity and ALP expression were significantly diminished when subjected to composite extracts or direct contact with the resin composites containing BAG fillers. However, after the preconditioning treatments in MEM and SHARP solutions, the biomimetic calcium phosphate minerals on 7.7 vol% BAG-loaded composites revealed unimpaired or even better cellular processes, including cell adhesion, cell proliferation, and early cell differentiation. Furthermore, resin composites with 1.9, 3.8, and 7.7 vol% BAG could not only reduce cell viability in S. mutans biofilm on the composite surface but also reduce the biofilm thickness and bacterial aggregations. This phenomenon was more evident in BAG7.7 due to the high ionic osmotic pressure and alkaline microenvironment caused by BAG dissolution. This study concludes that multi-functional bio-safe resin composites with mineralization and anti-biofilm properties can be achieved by adding low quantities of BAG into the resin system, which offers promising abilities to mineralize as well as prevent caries without sacrificing biological activity.

Objectives: The aim of present study was to examine the effect of Porphyromonas gingivalis (P.g.) adhesion on dental zirconia by characterizing the physical and chemical properties., Methods: Eighty polished-sintered zirconia discs were prepared and randomly distributed to 5 groups (n = 16): Zirconia cultured with - Group 1: broth containing P.g. for - 3 days; Group 2: 7 days; Group 3: broth (alone) for - 3 days; Group 4: 7 days; and Group 5: dry discs (negative control). After experimental period, broths were analyzed for pH and Zr release with inductively coupled plasma-optical emission spectroscopy (ICP-OES). The zirconia surface was evaluated by scanning electron microscope (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), water contact angle (WCA), and biaxial flexural strength (BFS)., Results: The mean pH with zirconia adhesion to P.g. group was significantly higher than the broth control (p < 0.05). As per ICP-OES, Zr ion/particulate release with P.g. adhesion to zirconia were significantly higher than the controls (p < 0.05). Post-experimental incubation, no defects were found on zirconia surfaces; tetragonal phase remained constant with no transformation to monoclinic phase but lower peak intensities were identified in experimental groups. WCA of zirconia surfaces with P.g. bacteria for 3 days (12.04° ± 2.05°) and 7 days (15.09° ± 2.95°) were significantly higher than zirconia surfaces immersed with broth (only) for 3 days (7.17° ± 1.09°) and 7 days (7.55° ± 0.65°), respectively (p < 0.05). BFS values of zirconia with P.g. for 3 days (632.57 ± 119.96 MPa) and 7 days (656.17 ± 100.29 MPa) were significantly lower than zirconia incubated in broth alone (765.01 ± 20.12 MPa) conditions (p < 0.05)., Significance: Under the conditions of present study, it can be concluded that P.g. adhesion on zirconia leads to structural alterations of dental zirconia further contributing to zirconia degradation., (Copyright © 2023 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Metals subjected to the oral environment are prone to corrosion over time and this can be harmful. Metallic restoration components such as dental subgingival implant abutments are exposed to pH changes and different ions while in contact with saliva. The aim of the study was to evaluate the corrosion resistance of titanium dental implant abutments and to compare and contrast the surface characteristics of these alloys before and after corrosion. The corrosion examination (E corr , j corr , OCP, polarization curve) of two implant abutments (TiDesign EV, Astra Tech, Dentsply, York, PA, USA; Individual Titanium Abutment, Apollo Implants Components, Pabianice, Poland) was performed in 0.9% NaCl and 5% HCl. Moreover, specimens were investigated using SEM-EDS before and after the corrosion test. The value of j corr in NaCl was higher for Astra (34.2 × 10 -8 ± 2.5 × 10 -8 A/cm 2 ) than for Apollo (8.8 × 10 -8 ± 2.5 × 10 -8 A/cm 2 ). Whereas, in HCl, the opposite relationship was observed (Astra 2.9 × 10 -4 ± 0.8 × 10 -4 A/cm 2 and Apollo 62.7 × 10 -4 ± 9.3 × 10 -4 A/cm 2 ). An average reactive anodic current density in NaCl for Astra amounted up to ~0.2 × 10 -5 -1.5 × 10 -5 A/cm 2 , while for Apollo-up to ~3.3-9.7 × 10 -7 A/cm 2 . The composition of both alloys after corrosion in NaCl demonstrated some changes: a decrease in the Ti, and Al and an increase in oxygen content. Hence, both alloys after corrosion in HCl demonstrated some minor changes in the elemental composition. Based on the results it can be concluded that: 1. Astra and Apollo abutments revealed good corrosion resistance and a passivation layer on the surface. 2. Apollo abutments exhibited better corrosion resistance in a neutral environment, suggesting that Astra abutments were found to be more resistant to corrosion in an acidic medium.

In-office bleaching, using hydrogen peroxide, is effective to remove dental enamel stains. However, bleaching agents can deteriorate surface properties of CAD-CAM materials. This in vitro study aimed to investigate the effect of in-office bleaching agents on Vickers hardness and surface topography of polished and unpolished dental CAD-CAM composite materials (Grandio blocs, Lava Ultimate, BRILLIANT Crios, Cerasmart), and a polymer-infiltrated ceramic network block (Vita Enamic). The specimens were randomly divided into two groups: unpolished or polished. The micro-hardness and surface topography of each group were measured before bleaching, after a 60 min bleaching period, and 24-h and one-month post-bleaching. In-office bleaching significantly influenced the Vickers hardness of both the polished and unpolished CAD/CAM composite blocks, with Vita Enamic exhibiting the least hardness stability among all groups. Furthermore, in-office bleaching significantly influenced the surface roughness of unpolished CAD/CAM composite blocks. There was a significant difference in hardness reduction between the polished and unpolished specimens for most of the investigated materials at different time points. The bleaching did not influence the surface roughness of the investigated polished group, except for Vita Enamic and Lava Ultimate. However, it did influence the surface roughness of the investigated materials in the unpolished group., (© 2023. Springer Nature Limited.)

Background: One of the crucial factors influencing the longevity of anterior aesthetic dental restorations is the colour stability of resin composites. Bleaching and whitening have become popular methods for enhancing dental aesthetics. Home whitening techniques, such as special pens, are widely available commercially. This in vitro study aimed to determine the efficiency of a whitening pen in removing tea stains from resin composite by measuring colour differences (ΔE 00 ). Additionally, the study aimed to evaluate the variations in colour parameters measured by extra-oral and intra-oral spectrophotometers., Methods: A total of 45 disc-shaped resin composite specimens were randomly divided into three groups; Group 1: stored in artificial saliva (control), Group 2: stored in artificial saliva followed by a whitening pen application, and Group 3: stored in tea followed by a whitening pen application. Colour measurements were taken three times for each specimen using two spectrophotometers (extra-oral and intra-oral devices); T1: before storage (baseline), T2: after storage in artificial saliva or tea for 6 days; and T3: after one week of whitening pen application in groups 2 and 3. The data were statistically analyzed using one-way ANOVA followed by the Tukey post hoc test ( p ≤ 0.05). The independent sample t -test was also employed. The equation of CIEDE2000 (ΔE 00 ) was used to calculate the colour difference between the dry, as-prepared specimens (baseline), and those after storage or bleaching. The colour changes exceeding the acceptability threshold (∆E 00 = 1.8) were considered unacceptable., Results: After whitening, the colour of the specimens stored in brewed tea (Group 3) remained unacceptable, as indicated by both the extra-oral and intra-oral spectrophotometers (ΔE 00 = 4 and 2.9, respectively). Groups 1 and 2 exhibited lower ΔE 00 values than Group 3 ( p = 0.01 *). No significant difference was observed between Group 1 (stored in artificial saliva) and Group 2 (stored in artificial saliva and then bleached) ( p = 0.3). Significant differences were consistently observed between the data obtained from the extra-oral spectrophotometer and the intra-oral one., Conclusions: The whitening pen proved ineffective in removing tea stains from resin composites. Although significant differences were found between the values obtained by the two spectrophotometers (extra-oral and intra-oral), both devices confirmed the unacceptable colour of the tea-stained resin composites after whitening.

Poly (methyl methacrylate) (PMMA), is an acrylic polymer substance that is mostly used for denture base applications. The purpose of this laboratory study was to investigate the effect of adding 0.05 wt.% Ag-doped carbon nanotubes (CNT) to PMMA-based (PMMA and MMA) denture base material on the impact strength, microhardness, and antimicrobial activity. A total of 60 heat-cured acrylic resin specimens were prepared. The specimens were randomly divided into two main groups ( n = 30/group), according to the powder used: (a) control group, using heat-cured PMMA; (b) treatment group, using a powder prepared by blending 0.05 wt.% silver-doped CNT nanoparticles with heat-cured PMMA. The impact strength, microhardness and anticandidal activity for each group were assessed via the Charpy, Vickers and agar diffusion tests, respectively ( n = 10/test for each subgroup). Data were analyzed using independent-sample t -tests ( p ≤ 0.05). The results of the impact strength test revealed that the treated heat-cured PMMA-MMA with Ag-doped CNT (2.2 kJ/mm 2 ) was significantly higher than that of the control heat-cured PMMA (1.6 kJ/mm 2 ). Similarly, the Vickers microhardness of the treatment group (52.7 VHN) was significantly higher than that of the control group (19.4 VHN). Regarding the agar diffusion test, after 24 h of incubation, the treated heat-cured PMMA with the Ag-doped CNT exhibited significantly higher anticandidal activity than that of the control group. Therefore, Ag-doped carbon nanotubes could be considered as promising fillers for the dental heat-cured acrylic resin to improve the resistance of the resultant denture against sudden fractures, scratching, and candida invasion.

This study investigated the diagnostic accuracy of CBCT for detection of accessory mental foramina (AMFs) in dry mandibles using two different devices and three different CBCT imaging modalities. A total of 40 dry mandibles (20 per group) were selected to generate corresponding CBCT images, each with three different CBCT imaging modalities (high, standard, and low doses), using ProMax 3D Mid (Planmeca) and Veraview X800 (J. Morita). The presence, count (n), location, and diameter of the AMFs were measured on both dry mandibles and CBCT scans. The Veraview X800 with different imaging modalities showed the highest accuracy (97.5%), while the ProMax 3D Mid in low-dose imaging modality exhibited the lowest accuracy (93.8%). The most common AMF sites on dry mandibles were anterior-cranial and posterior-cranial, while anterior-cranial was the most frequent on CBCT scans. As for AMF diameter, the mean mesiodistal and vertical diameters on dry mandibles were 1.89 mm and 1.47 mm, respectively, which were greater or equal to the values obtained from CBCT scans. The overall diagnostic accuracy for assessing AMFs exhibited good results, but some caution is warranted when using a low-dose imaging modality with a large voxel size (400 μm).

Quaternary ammonium compounds (QACs) have been widely used due to their excellent antimicrobial activity. However, using the technology where nanomaterials are employed as drug carriers to deliver QAC drugs has not been fully explored. In this study, mesoporous silica nanoparticles (MSNs) with short rod morphology were synthesized in a one-pot reaction using an antiseptic drug cetylpyridinium chloride (CPC). CPC-MSN were characterized via various methods and tested against three bacterial species ( Streptococcus mutans , Actinomyces naeslundii , and Enterococcus faecalis ), which are associated with oral infections, caries, and endodontic pathology. The nanoparticle delivery system used in this study prolonged the release of CPC. The manufactured CPC-MSN effectively killed the tested bacteria within the biofilm, and their size allowed them to penetrate into dentinal tubules. This CPC-MSN nanoparticle delivery system demonstrates potential for applications in dental materials.

Objectives: This study utilised an Artificial Intelligence (AI) method, namely 3D-Deep Convolutional Generative Adversarial Network (3D-DCGAN), which is one of the true 3D machine learning methods, as an automatic algorithm to design a dental crown., Methods: Six hundred sets of digital casts containing mandibular second premolars and their adjacent and antagonist teeth obtained from healthy personnel were machine-learned using 3D-DCGAN. Additional 12 sets of data were used as the test dataset, whereas the natural second premolars in the test dataset were compared with the designs in (1) 3D-DCGAN, (2) CEREC Biogeneric, and (3) CAD for morphological parameters of 3D similarity, cusp angle, occlusal contact point number and area, and in silico fatigue simulations with finite element (FE) using lithium disilicate material., Results: The 3D-DCGAN design and natural teeth had the lowest discrepancy in morphology compared with the other groups (root mean square value = 0.3611). The Biogeneric design showed a significantly (p < 0.05) higher cusp angle (67.11°) than that of the 3D-DCGAN design (49.43°) and natural tooth (54.05°). No significant difference was observed in the number and area of occlusal contact points among the four groups. FE analysis showed that the 3D-DCGAN design had the best match to the natural tooth regarding the stress distribution in the crown. The 3D-DCGAN design was subjected to 26.73 MPa and the natural tooth was subjected to 23.97 MPa stress at the central fossa area under physiological occlusal force (300 N); the two groups showed similar fatigue lifetimes (F-N curve) under simulated cyclic loading of 100-400 N. Designs with Biogeneric or technician would yield respectively higher or lower fatigue lifetime than natural teeth., Significance: This study demonstrated that 3D-DCGAN could be utilised to design personalised dental crowns with high accuracy that can mimic both the morphology and biomechanics of natural teeth., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

This review aims to provide a comprehensive analysis of the characterizations of bioactive glass (BAG)-loaded dental resin-based composite materials. Online databases (Web of Science, PubMed, and Science Direct) were used to collect data published from January 2011 to January 2022. Only BAG-containing resin adhesive and resin restorative composites are discussed in this narrative review. BAG-loaded resin composites exhibit excellent mineralization ability reflecting enhanced ion release, pH elevation, and apatite formation, especially regarding high BAG loading. This aids the anti-demineralization and remineralization of teeth. Furthermore, BAG-loaded resin composites demonstrated in vitro biocompatibility and antibacterial performance. It has been suggested that BAG fillers with small particle sizes and no more than 20 wt% in terms of loading amount should be used to guarantee the appropriate mechanical properties of resin composites. However, most of these studies focused on one or some aspects using different resin systems, BAG types, and BAG amounts. As such, this makes the comparison difficult, and it is essential to find an optimal balance between different properties. BAG-loaded resin composites can be regarded as bioactive materials, which present major benefits in dentistry, especially their capability in the bacterial inhibition, cell biocompatibility, anti-demineralization, and remineralization of teeth.

Purpose: This study explores novel solutions other than standard SBF for biomimetic evaluations of mineralization particularly for resin composites containing bioactive glass (BAG)., Methods: Experimental UDMA/TEGDMA resin composites with 0.0, 1.9, 3.8 or 7.7 vol% of 45S5 BAG fillers were prepared. Besides simulated body fluid (SBF) as control, the specimens were immersed in three other solutions either with bicarbonate which are Hank's balanced salt solution (HBSS) and cell culture medium (MEM), or without bicarbonate which is a novel Simple HEPES-containing Artificial Remineralization Promotion (SHARP) solution, for 3, 7 and 14 days. These solutions were then analyzed by ICP-OES and pH meter, and the surfaces of the BAG composites were analyzed by SEM, XRD and FTIR., Results: ICP-OES revealed Ca and P concentration continuously decrease, while Si concentration increases with time in the solutions other than SBF, which showed almost unchanged elemental concentration. Only SHARP solution is able to maintain a constant pH over the immersion time. SEM, together with XRD and FTIR, showed nano-sized octacalcium phosphate (OCP) nanospheres formation on 3.8 and 7.7 vol% BAG composites after 14 days immersion in HBSS (500-600 nm) and MEM (300-400 nm). SHARP solution enabled OCP formation after 3 days and then self-assembled into urchin-like carbonated hydroxyapatite (CHA) microspheres encompassed with nanorods of 100 nm width and 8 µm length after 14 days of immersion for 7.7 vol% BAG composites., Conclusion: This study suggests SHARP solution can evaluate mineralization biomimetically whereas CHA microspheres can be formed on BAG-containing resin composites.

Purpose: Measurement of bacterial adhesion has been of great interest for different dental materials. Various methods have been used for bacterial counting; however, they are all indirect measurements with estimated results and therefore cannot truly reflect the adhesion status. This study provides a new direct measurement approach by using a simple artificial intelligence (AI) method to quantify the initial bacterial adhesion on different dental materials using Scanning Electron Microscope (SEM) images. Materials and Methods: Porphyromonas gingivalis ( P.g. ) and Fusobacterium nucleatum ( F.n. ) were used for bacterial adhesion on dental zirconia surfaces, and the adhesion was evaluated using SEM images at time points of one, seven, and 24 h(s). Image pre-processing and bacterial area measurement were performed using Fiji software with a machine learning plugin. The same AI method was also applied on SEM with Streptococcus mutans ( S.m. ) inoculated PMMA nano-structured surface at 1, 24, 72, and 168 h(s), and then further compared with the CLSM method. Results: For both P.g. and F.n. initiation adhesion on zirconia, a new linear correlation (r 2 > 0.98) was found between bacteria adhered area and time, such that: b acteria   adhered   area   ( m m 2 ) ∝ log ⁡ ( time ) For S.m. on PMMA surface, live/dead staining CLSM method and the newly proposed AI method on SEM images were strongly and positively associated (Pearson's correlation coefficient r  > 0.9), i.e. both methods are comparable. Conclusions: SEM images can be analyzed directly for both morphology and quantifying bacterial adhesion on different dental materials' surfaces by the simple AI-enabled method with reduced time, cost, and labours., Competing Interests: No potential conflict of interest was reported by the author(s)., (© 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)

Objectives: To evaluate the biocompatibility and mechanical properties of experimental bis -phenol-A and bis -GMA free E-glass fiber-reinforced composites (FRCs) prepared with hexanediol dimethacrylate (HDDMA) based resin., Methods: Two ratios of HDDMA/TEGDMA resin were evaluated: exp-1 (70/30 wt.%) and exp-2 (50/50 wt.%) with two bis -GMA resin control groups ( bis -GMA/MMA and bis -GMA/TEGDMA resins, both 70/30 wt.%). E-glass fibers were embedded into the resins to prepare FRCs specimens. Biocompatibility was assessed for cytoviability and biofilm formation with Streptococcus mutans , Streptococcus sanguinis , Enterococcus faecalis, and Candida albicans . Mechanical properties were evaluated for flexural strength and hardness (24 h, water storage 1 and 28 days), water sorption (1, 7, 14, and 28 days), contact angle, and surface roughness. The data were analyzed statistically by one-way and two-way ANOVA (p < 0.05)., Results: Cytoviability of the experimental groups was significantly higher than the control groups (p < 0.05). The exp-1 cytoviability (98.2 ± 1.3%) met the ISO 10993-5 standard requirement for noncytotoxic materials. The adherence of bacteria to the experimental FRCs was visibly less than the controls, while Candida albicans adhered visibly more to the experimental groups than the controls (p < 0.05). Flexural strength showed slightly higher values for controls than for the experimental groups. The exp-1 hardness value was significantly higher in the control groups for all storage conditions (p < 0.05). The water sorption of the experimental groups was significantly higher than the controls. The surface roughness indicated no significant difference (p = 0.87). The exp-1 showed a higher contact angle with the control groups., Conclusion: The experimental HDDMA/TEGDMA-based FRCs might be potential alternatives for bis -GMA-based FRCs., Clinical Significance: The HDDMA/TEGDMA E-glass FRCs might provide biocompatible restorations., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors.)

The present dry-mandible study evaluated the presence of the mental (MF), lingual (LF), and retromolar (RMF) foramina to assess the accuracy of CBCT in detecting these anatomical structures. In total, 38 human dry mandibles were analyzed (30 men, 8 women; mean age: 61.9 ± 13.7 years). CBCT scans were taken using low-dose parameters, and LF, MF, and RMF were assessed visually and radiographically. Both the presence (yes/no) and the count (n) of each foramen were compared between CBCTs and visual assessment. For the presence assessment, only RMF exhibited a significant difference between CBCT and visual inspection (P = .035). For count, the RMF (P = .049) and paramedian LF (P = .003) exhibited differences between the two methods. The agreement between CBCT and visual inspection was excellent for the MF, moderate-excellent for the LF, and low-moderate for the RMF. Intra- and interassessor agreement varied from excellent (MF), to moderate-excellent (LF), and low-moderate (RMF). The LF and RMF represent challenging structures to identify on CBCT images due to their limited dimension. False negative findings in CBCTs in the assessment of foramina, especially LF, might lead to surgical complications during implant surgery.

Guided tissue regeneration (GTR) membranes are used for treating chronic periodontal lesions with the aim of regenerating lost periodontal attachment. Spatially designed functionally graded bioactive membranes with surface core layers have been proposed as the next generation of GTR membranes. Composite formulations of biopolymer and bioceramic have the potential to meet these criteria. Chitosan has emerged as a well-known biopolymer for use in tissue engineering applications due to its properties of degradation, cytotoxicity and antimicrobial nature. Hydroxyapatite is an essential component of the mineral phase of bone. This study developed a GTR membrane with an ideal chitosan to hydroxyapatite ratio with adequate molecular weight. Membranes were fabricated using solvent casting with low and medium molecular weights of chitosan. They were rigorously characterised with scanning electron microscopy, Fourier transform infrared spectroscopy in conjunction with photoacoustic sampling accessory (FTIR-PAS), swelling ratio, degradation profile, mechanical tensile testing and cytotoxicity using human osteosarcoma and mesenchymal progenitor cells. Scanning electron microscopy showed two different features with 70% HA at the bottom surface packed tightly together, with high distinction of CH from HA. FTIR showed distinct chitosan dominance on top and hydroxyapatite on the bottom surface. Membranes with medium molecular weight showed higher swelling and longer degradation profile as compared to low molecular weight. Cytotoxicity results indicated that the low molecular weight membrane with 30% chitosan and 70% hydroxyapatite showed higher viability with time. Results suggest that this highly segregated bilayer membrane shows promising potential to be adapted as a surface layer whilst constructing a functionally graded GTR membrane on its own and for other biomedical applications.

Purpose To seek a simple solution that can recycle and regenerate dental CAD/CAM zirconia green blanks from its waste residuals.Methods Waste residuals (3M® Lava™ Plus HT) were pulverized after dry milling and cutting, and subsequently sieved before pickling in a 0.5 M nitric acid. These powders were then dry-pressed and pre-sintered into blocks at seven different temperatures in the range 800-1100 °C. New zirconia blocks flagged with the same batch numbers were used as control. These blocks were cut into bars before subjected them to manufacturer-recommended sintering at 1450 °C. Crystalline phases (by XRD), elemental compositions (by EDX), surface morphologies (by SEM), machinability, linear shrinkage rate, relative density, and Knoop microhardness were evaluated before and after sintering, and four-point flexural strengths were also evaluated for the sintered zirconia bars.Results Only tetragonal phases were found in both pre- and fully-sintered recycled zirconia blocks. SEM results showed that pre-sintered samples at 950 °C had smooth and flat surfaces with evenly distributed particles. Recycled and control zirconia blocks had similar elemental compositions. Results from machined surface, linear shrinkage rate, relative density, and Knoop microhardness established that 950 °C and 1000 °C were suitable pre-sintering temperatures for recycling zirconia. Pre-sintered recycled zirconia had no significant differences in flexural strengths, however, samples pre-sintered at 1000 °C exhibited the closest value (897 MPa) compared to that of the control (904 MPa).Conclusions Dental CAD/CAM zirconia can be recycled and reused from its waste residuals by adopting a simple method that requires a pre-sintering at 950 or 1000 °C.

The purpose of the study was to measure the cement thickness obtained when ceramic rods were luted to dentin and to analyze the relation between cement thickness and the previously published tensile bond strength of similar test specimens. In addition, the ISO standard 4049:2019 method was used to determine the film thickness of the used cements. Zirconia (n = 100) and lithium disilicate (n = 50) rods were cemented to bovine dentin using one of five different resin-based cements. The ceramic-dentin test specimens were cut into two slices and the cement thickness was measured using a scanning electron microscope and compared to the bond strength values of similar specimens already published. The mean cement thickness recorded for ceramic rods cemented to dentin was in the range 20-40 μm, which was larger than the cement film thickness found by the ISO method. The cement film thickness determined according to ISO standard methods did not concur with the results obtained when cementing ceramic rods to dentin. For cementing ceramic restorations, a cement thickness in the range 25-35 μm seems to be favorable for the bond strength., (© 2021 The Authors. European Journal of Oral Sciences published by John Wiley & Sons Ltd on behalf of Scandinavian Division of the International Association for Dental Research.)

Objective: This literature research aimed to compare, contrast and quantify the innovations in the most commonly used dental biomaterials., Methodology: Original research articles based on experimental dental biomaterials published between 2007 and 2019 were retrieved and reviewed. A search of electronic databases, PubMed, Scopus, and Web of Science indexed dental/biomaterials journals, has been conducted. The inclusion criteria in this research were: synthesis of experimental dental materials, whereas commercial dental materials, review articles, and clinical trials (case reports) were excluded., Results: It was found that the amount of publications related to dental subgingival implants, computer-aided modeling ceramics, aesthetic restorative materials, adhesives cements, ceramics, bioceramics, endodontic materials, bioactive scaffolds, stem cells, and guided-tissue membranes had increased significantly from 2007. At the same time, the number of publications related to dental cements, silver amalgam, and dental alloys has decreased. For characterization of dental materials it was noted that mechanical properties were tested mostly for restorative materials. On the other hand, biological properties were most assessed for dental subgingival implants and endodontic materials, however, physical properties predominantly for bioceramics., Conclusion: It is concluded that to meet clinical demands there was more focus on restorative materials that provided better aesthetics, including resin composites, adhesive resin composites (luting cements), zirconia, and other ceramics. The boost in laboratory and animal research related to bioceramics was attributed to their regenerative potential. This current literature study will help growing researchers to consider and judge the direction to which research might be guided in order to plan prospective research projects., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 The Authors.)

Enterococcus faecalis as an important nosocomial pathogen is critically implicated in the pathogenesis of endocarditis, urinary tract, and persistent root canal infections. Its major virulence attributes (biofilm formation, production of proteases, and hemolytic toxins) enable it to cause extensive host tissue damage. With the alarming increase in enterococcal resistance to antibiotics, novel therapeutics are required to inhibit E. faecalis biofilm formation and virulence. Trans -cinnamaldehyde (TC), the main phytochemical in cinnamon essential oils, has demonstrated promising activity against a wide range of pathogens. Here, we comprehensively investigated the effect of TC on planktonic growth, biofilm formation, proteolytic and hemolytic activities, as well as gene regulation in E. faecalis . Our findings revealed that sub-inhibitory concentrations of TC reduced biofilm formation, biofilm exopolysaccharides, as well as its proteolytic and hemolytic activities. Mechanistic studies revealed significant downregulation of the quorum sensing fsr locus and downstream gelE , which are major virulence regulators in E. faecalis . Taken together, our study highlights the potential of TC to inhibit E. faecalis biofilm formation and its virulence.

Purpose: To test the hypothesis that surface roughening and polishing of ceramics have no effect on their surface roughness and biofilm adhesion., Materials and Methods: Feldspathic ceramic Vitablocks™ TriLuxe forte (VTF), lithium disilicate glass IPS e.max Press™ (IPS) and zirconia reinforced lithium silicate Vita Suprinity™ (VS) ceramic blocks (n = 27 per group) were prepared from sintered CAD blocks using a water-cooled saw. They were further subdivided into 3 subgroups according to the surface treatment protocols (n = 9): as prepared, roughened and polished. The surface roughness of the ceramic blocks was measured using an electro-mechanical profilometer. The ceramic sections were inoculated with Streptococcus mutans and incubated for 48 hours to form a biofilm. The ceramic surfaces with the biofilms were analyzed using Confocal Laser Scanning Microscopy to calculate the percentage of live bacteria and substratum coverage by the biofilm, and further visualized using scanning electron microscopy. Statistical analysis was done with SPSS software using two-way ANOVA, followed by post hoc Bonferroni test to identify significant differences between the groups. The level of significance was set at p = 0.05., Results: As prepared VTF showed significantly higher mean surface roughness values than as prepared IPS and VS. The mean percentage of live bacteria and biofilm coverage of the substrate were significantly higher in the roughened ceramic blocks than the as prepared and polished blocks for all three ceramic types (p < 0.05). Polished specimens of VS significantly lower percentage of biofilm coverage than the other groups (p < 0.05)., Conclusions: This study sheds new light that adjustments of ceramic restorations prior to cementation increases the likelihood for formation and adhesion of microbial biofilms on the surface. Polished zirconia reinforced lithium disilicate ceramics demonstrated the lowest bacterial adhesion among the evaluated ceramics., (© 2020 by the American College of Prosthodontists.)

Despite the widespread observations on the osteogenic effects of magnesium ion (Mg 2+ ), the diverse roles of Mg 2+ during bone healing have not been systematically dissected. Here, we reveal a previously unknown, biphasic mode of action of Mg 2+ in bone repair. During the early inflammation phase, Mg 2+ contributes to an upregulated expression of transient receptor potential cation channel member 7 (TRPM7), and a TRPM7-dependent influx of Mg 2+ in the monocyte-macrophage lineage, resulting in the cleavage and nuclear accumulation of TRPM7-cleaved kinase fragments (M7CKs). This then triggers the phosphorylation of Histone H3 at serine 10, in a TRPM7-dependent manner at the promoters of inflammatory cytokines, leading to the formation of a pro-osteogenic immune microenvironment. In the later remodeling phase, however, the continued exposure of Mg 2+ not only lead to the over-activation of NF-κB signaling in macrophages and increased number of osteoclastic-like cells but also decelerates bone maturation through the suppression of hydroxyapatite precipitation. Thus, the negative effects of Mg 2+ on osteogenesis can override the initial pro-osteogenic benefits of Mg 2+ . Taken together, this study establishes a paradigm shift in the understanding of the diverse and multifaceted roles of Mg 2+ in bone healing.

Objectives: The objectives of the study were (1) to develop a novel multi-element-doped porous 58S bioactive glass coating for titanium implants and (2) to investigate the physiochemical, cell cytotoxic and antibacterial properties of this novel coating for titanium implants., Methods: This study employed the sol-gel method to develop a silver-, cobalt (II) oxide- and titanium dioxide-doped 58S bioactive glass coating. The surface topography and in vitro bioactivity of the new bioactive glass-coated implants were studied using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy. The surface nanohardness and coating degradation were evaluated using atomic force microscopy (AFM) and inductively coupled plasma atomic emission spectroscopy (ICP-AES), respectively. The cell cytotoxicity was assessed using cell viability of osteoblast-like mouse cells. The antibacterial property was examined using colony-forming units (CFUs) of the implant coating against Porphyromonas gingivalis ., Results: The multi-element-doped porous 58S bioactive glass-coated titanium implant was synthesized. SEM showed that calcium phosphate was formed on the novel coating but not on the 58S bioactive glass coating. The mean surface nanohardness of the novel coating and the 58S coating were 124 ± 24 and 50 ± 17 MPa, respectively ( p < 0.001). ICP-AES showed that the releases of Si, Ca and P ions of the novel coating were significantly higher than that of a 58S bioactive glass-coated implant. No significant difference in cell cytotoxicity was found between the novel coating and the 58S coating ( p > 0.1). The mean CFUs of the novel coating and the conventional coating were 120 × 10 6 and 49 × 10 6 /mL., Conclusion: A novel multielement-doped porous bioactive glass coating for titanium implants was developed. The coating displays promising biocompatibility and antibacterial activity., Clinical Significance: the coating can be used to improve the clinical success of dental implants for patient care if it shows success in clinical trials.

Objective: The effects of saliva on demineralized dentin and silver diamine fluoride (SDF) were investigated in vitro., Methods: Dentin samples stored in deionized water (DIW), buffer solution (BS), basal medium mucin (BMM), and unstimulated whole saliva (UWS) were demineralized for 3 days and immersed in the same storage media. SDF as a 38 mass% solution was applied to the dentin samples for 3 minutes after they had been replaced in their respective medium. Surfaces were analyzed by scanning electron microscopy, energy-dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD)., Results: Scanning electron microscopy showed various surface deposits and coatings, including occlusion of dentinal tubules. DIW resulted in the thinnest coating, whereas BMM resulted in the thickest. EDX and XPS showed the formation of metallic silver and silver compounds in all four media, with the greatest formation in BS. XRD indicated that the main product was silver chloride except in DIW. Sulphur was found in BMM and UWS. EDX and XPS detected fluoride and XRD detected calcium fluoride and fluorohydroxyapatite in BS, BMM, and UWS., Conclusion: The interaction between SDF and demineralized dentin was dependent upon the storage medium. BMM provided an outcome most similar to human saliva.

Objectives: To use both absolute anteroposterior maxillary complex length (APMCL) and relative APMCL to investigate the relationship between the maxillary complex, its individual bony segments, and their association to the anterior cranial base. In addition, the relationship between length and position of the maxillary complex was analyzed., Materials and Methods: Sixty human skulls were analyzed using cone beam computed tomography. The maxillary complex length was measured between anterior and posterior nasal spine (ans-pns), and the average was used as the cut-off to identify a high- and a low-length group based on absolute APMCL. The length ratio between the maxillary complex and the anterior cranial base (ans-pns/SN) was used to identify the two groups based on relative APMCL. The anterior cranial base length and the lengths of the maxillary complex bones were compared between the high- and low-length groups., Results: Based on absolute APMCL, individuals with shorter maxillary complex had shorter anterior cranial base (P = .003), representing normal proportions. Based on relative APMCL, individuals with shorter maxillary complex had longer anterior cranial base and vice versa (P = .014), indicating disproportions. Individuals with shorter maxillary complex exhibited shorter maxilla (Δ = -1.5 mm, P = .014)., Conclusions: When skeletal deformity of the midface is suspected, individual disproportions in the anteroposterior length of the maxillary complex in relation to the anterior cranial base (relative measurements) should be assessed through radiological imaging. A shorter maxillary complex may be associated with a shorter maxilla, and not with a shorter premaxilla or palatine bone., (© 2021 by the EH Angle Education and Research Foundation, Inc.)

Purpose: Fiber-reinforced composites (FRCs) have received considerable attention, owing to their potential use in dental prostheses or bone fracture fixation applications. The aim of this systematic review was to analyze and report the biological properties of FRCs reported in the existing literature., Study Selections: A systematic search of four databases (PubMed/MEDLINE, Scopus, Web of Science, and Cochrane library) was performed to identify all relevant studies published between 1962 and 2019. The search was limited to laboratory-based studies published in English. Citation mining was also performed through cross-referencing of included studies and hand searching of relevant journals., Results: A total of 1283 potentially relevant articles were initially identified, and thirty-three articles were full-text screened. In the final ten studies included for review, four investigated bacterial adhesion and growth abilities on FRCs, four investigated the fibroblastic cytotoxicity of different surface-treated FRCs, and two investigated the osseointegration between bone and FRCs. Owing to the heterogeneity of fiber types, FRC-coating, and lack of standardized testing protocols, a meta-analysis was not feasible. The included studies indicated that glass fibers, and in particular E-glass fibers, are superior to ceramics and other FRCs in terms of bacterial adherence, fibroblast cytotoxicity, and cell viability., Conclusions: Glass-fiber-reinforced composites are cytocompatible materials that possess satisfactory biological properties and can be used in dental prosthesis and craniofacial implants. Further research is necessary to regulate the matrix ion release/degradation of FRCs to prolong the initially demonstrated properties.

This aim was to assess the biomechanical and biocompatibility properties of novel glass fibre-reinforced composites (FRCs) with a fluorinated urethane dimethacrylate (FUDMA) resin. Three ratios of FUDMA/TEGDMA (30/70 wt%, 50/50 wt%, 70/30 wt%) and two ratios of control FRCs with bis-GMA/TEGDMA (50/50 wt% and 70/30 wt%) containing long silanized E-glass fibres were prepared. Despite 70 wt% bis-GMA-FRC showed a significantly higher flexural strength (p < 0.05), 50 wt% FUDMA- and bis-GMA-FRCs were not differ from each other. The greatest surface hardness and weight increase after water storage were found in 70 wt% and 30 wt% FUDMA-FRCs, respectively. No significant difference was found in water sorption and solubility among all groups. Average surface roughness was 1.80 ± 0.05 μm, while 70 wt% FUDMA-FRC exhibited the greatest contact angle (p > 0.05). Viabilities and ALP activities of MC3TC-E1 cells in all FUDMA-FRCs were higher than bis-GMA-FRCs after 5 days. To conclude, the novel FUDMA-FRCs are potential substitutes that exhibited superior cytocompatibility properties but comparable biomechanical properties to bis-GMA-FRCs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Objective: Proteolytic and demineralizing agents have a profound influence on the dentin ultrastructure, which plays a key role in the mechanical integrity of the tooth and integrity of dentin-biomaterial interfaces. In-depth characterization of dentin treated with a novel root canal irrigation protocol comprising sodium hypochlorite (NaOCl) and etidronate (HEDP) is lacking. This study comprehensively characterized and compared the effects of the continuous chelation (NaOCl/HEDP) and sequential chelation (NaOCl/EDTA) protocols on dentin., Methods: Dentin blocks, dentin powder and root canals of mandibular premolars were distributed into Group 1, Saline (control); Group 2, NaOCl/EDTA; and Group 3, NaOCl/HEDP. Ultrastructural characteristics of the treated dentin were investigated using electron microscopy and light microscopy, while the surface roughness was analyzed using atomic force microscopy. Chemical compositional changes were characterized using Fourier transform infrared spectroscopy (FTIR) and energy-dispersive-X-ray spectroscopy (EDS), while collagen degradation was determined using ninhydrin assay. Data were statistically analyzed using multiple-factor one-way ANOVA and Tukey HSD tests (P = 0.05)., Results: NaOCl/HEDP resulted in partially degraded, yet mineralized collagen fibers, with minimal alteration to the subsurface matrix. Conversely, NaOCl/EDTA dissolved the hydroxyapaptite encapsulation, exposing collagen fibre bundles. There was no significant difference in the surface roughness between the two protocols (P > 0.05). NaOCl/HEDP resulted in homogenous distribution of organic and inorganic components on the treated surface., Significance: This study highlighted that continuous chelation (NaOCl/HEDP) resulted in a frail surface collagen layer while sequential chelation (NaOCl/EDTA) exposed bare collagen fibres. These surface and sub-surface effects potentially contribute to structural failures of dentin and/or dentin-biomaterial interfacial failures., (Copyright © 2020 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Technological advances have made it possible to examine dental resin composites using 3D nanometer resolution. This investigation aims to characterize existing dental nano-hybrid and micro-hybrid resin composites through comparing and contrasting nano-computed tomography (nano-CT) with micro-CT and high-resolution SEM images. Eight commercially available and widely used dental resin composites, 2 micro-hybrid and 6 nano-hybrid were researched. Cured samples were examined and characterized using nano-CT (resolution 450 nm) and compared with micro-CT images (resolution 2 µm). Acquired images were reconstructed and image analysis was carried out to determine porosity and pore morphology. A comprehensive comparison of scanning micrograph images unsurprisingly revealed that the nano-CT images displayed greater detail of the ultrastructure of cured dental resin composites. Filler particle diameters and its volumes were lower when measured using nano-CT, porosity being higher where analysed at higher resolution. There were large variations between the examined materials. Fewer voids were found in Tetric EvoCeram and IPS Empress Direct, the smallest pores being found in Universal XTE and Tetric EvoCeram. Nano-CT was successfully used to investigate the morphology of dental resin composites and showed that micro-CT gives a lower porosity and pore size but overestimates filler particle size. There were large discrepancies between the tested composites. Evidence of porosities and pores within a specimen is a critical finding and it might have a detrimental effect on a material's clinical performance.

Zirconia (ZrO 2 ) ceramic is widely used in dentistry as a clinical dental biomaterial. In this review, we are focusing on and summarizing the biological performance of zirconia under different surface characteristics. We have included an initial tissue cell attachment study on zirconia and bacterial adhesion on zirconia. Our results suggest that surface modifications applied on zirconia may change the interfacial surface characteristics e.g. surface roughness, surface free energy, and chemistry of zirconia. The modifications also result in advanced biological performance of zirconia, including enhanced tissue cell attachment and reduction of bacterial adhesion. The recent laboratory research has provided many interesting modification methods and showed clinically interesting and promising outcomes. A few of the outcomes are validated and have been applied in clinical dentistry.

To study the antimicrobial effects of quaternary ammonium silane (QAS) exposure on Streptococcus mutans and Lactobacillus acidophilus bacterial biofilms at different concentrations. Streptococcus mutans and Lactobacillus acidophilus biofilms were cultured on dentine disks, and incubated for bacterial adhesion for 3-days. Disks were treated with disinfectant (experimental QAS or control) and returned to culture for four days. Small-molecule drug discovery-suite was used to analyze QAS/Sortase-A active site. Cleavage of a synthetic fluorescent peptide substrate, was used to analyze inhibition of Sortase-A. Raman spectroscopy was performed and biofilms stained for confocal laser scanning microscopy (CLSM). Dentine disks that contained treated dual-species biofilms were examined using scanning electron microscopy (SEM). Analysis of DAPI within biofilms was performed using CLSM. Fatty acids in bacterial membranes were assessed with succinic-dehydrogenase assay along with time-kill assay. Sortase-A protein underwent conformational change due to QAS molecule during simulation, showing fluctuating alpha and beta strands. Spectroscopy revealed low carbohydrate intensities in 1% and 2% QAS. SEM images demonstrated absence of bacterial colonies after treatment. DAPI staining decreased with 1% QAS (p < 0.05). Fatty acid compositions of dual specie biofilm increased in both 1% and 2% QAS specimens (p < 0.05). Quaternary ammonium silane demonstrated to be a potent antibacterial cavity disinfectant and a plaque inhibitor and can be of potential significance in eliminating caries-forming bacteria.

Despite the vast literature on the effects of root canal irrigants on the dentin characteristics, the precise effects of clinically relevant irrigation sequences remain unclear. In this review, we systematically dissect the role of different sequential irrigation approaches that are used in clinical endodontics. Using a systematic search strategy, we attempt to answer the question: 'Which irrigating sequence has the most deleterious effects on dentin structure and properties?' The effect of irrigants on the dentin composition and mechanical properties have been reviewed. A wide variety of concentrations, duration and techniques have been employed to characterize the effects of chemicals on dentin properties, thus making it impossible to draw guidelines or recommendations of irrigant sequences to be followed clinically. It was apparent that all the studied irrigation sequences potentially result in some deleterious effects on dentin such as decrease in the flexural strength, microhardness, modulus of elasticity and inorganic content and organic-inorganic ratio of the dentin. However, the literature still lacks comprehensive investigations to compare the deleterious effect of different irrigation sequences, using a wide variety of qualitative and quantitative methods. Such investigations are essential to make clinical recommendations and strategize efforts to minimize chemically-induced damage to dentin characteristics., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported., (Copyright © 2020. The Korean Academy of Conservative Dentistry.)

Objectives: To evaluate transesterification based dissolution of dimethacrylate and epoxy polymers, the former containing ester groups. Polymer substrates were treated with an adhesive resin (Stick™ Resin) and an organic catalyst-alcohol solution (ethylene glycol and triazabicyclodecene). The surface was chemically and nanomechanically analyzed with Fourier Transform-Infrared (FTIR) spectroscopy, surface profile peak (R p ) and nanohardness and modulus of elasticity., Methods: A total of 100 specimens each of light-cured dimethacrylate polymer and heat-cured diepoxy polymer were prepared. 20 specimens were randomly selected and used as control group (0s). The remaining specimens were randomly divided into 40 each for treatment with an Stick™ resin and ethylene glycol+triazabicyclodecene. Within each group the 40 specimens were randomly subdivided into 20 each for treatment at 5min and 24h, with 10 specimens for FTIR and nanohardness and modulus of elasticity, and the other 10 for SEM and surface R p analyses., Results: Dimethacrylate polymer showed a reduction in the nanohardness and modulus of elasticity, R p values and SEM also showed significant topographical changes after being treated with either Stick™ resin or ethylene glycol+triazabicyclodecene, whereas epoxy resin substrate did not. FTIR analyses affirmed changes in the intensity of ester groups., Significance: Ester group containing dimethacrylate polymer showed a reduction in NMP within 5min of exposure to the treatment agents with softening by solution ethylene glycol+triazabicyclodecene associated to the reduction of ester groups in the polymer structure by transesterification. Epoxy polymer without ester groups was not affected by surface softening with treatment agents. Adhesive resin caused surface swelling., (Copyright © 2020 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Zirconia has become an excellent choice of dental implants because of its excellent mechanical strength, aesthetic, and biocompatibility. Although some studies have shown ultraviolet (UV) irradiation is effective to photofunctionalize dental zirconia that can improve osteoblastic function, the scattered information has not identified the most effective exposure time and wavelength of UV. Herein, this study has investigated the effects of UV irradiation on zirconia after UV-A (365 nm) or UV-C (243 nm) photofunctionalization for different times (15 min, 3 and 24 h). After irradiation, the zirconia surface was analyzed by color spectrophotometry, scanned electron microscopy (SEM), energy-dispersive X-ray spectrometry, water contact angle (WCA) with goniometer, and X-ray diffraction. Osteoblastic (MC3T3-E1) cells were cultured on zirconia discs and evaluated with a CCK-8 test kit for cell proliferation (3 h and 1 day) and with alkaline phosphatase (ALP) activity (14 days). Significant color change (Δ E ) was observed by irradiating with UV-C for 15 min (1.99), 3 h (1.92), and 24 h (3.35), whereas only minute changes were observed with UV-A (respectively, Δ E : 0.18, 0.14, 0.57). No surface textural changes were observed nor a monoclinic phase was detected on both the UV-A and UV-C irradiated samples. UV-C significantly decreased the C/Zr ratios and WCA, with irradiating for 24 h presenting the lowest values, and it was the only condition to give significantly higher ALP activity at 14 days ( p < 0.05) and CCK-8 values for 1 day culture ( p < 0.05). It is concluded that UV-C (but not UV-A) irradiation can significantly change the aesthetic in color, and only prolonged 24 h UV-C irradiation can enhance MC3T3-E1 cell adhesion on zirconia by photofunctionalization., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Titanium and its alloys are widely used in biomedical devices, e.g. implants, due to its biocompatibility and osseointegration ability. In fact, fungal ( Candida spp.) infection has been identified as one of the key reasons causing the failure of the device that is inevitable and impactful to the society. Thus, this study evaluated the surface morphology, surface chemical composition and Candida albicans adhesion on specimens of 16 binary Ti-alloys (∼5 wt% of any one of the alloy elements: Ag, Al, Au, Co, Cr, Cu, Fe, In, Mn, Mo, Nb, Pd, Pt, Sn, V and Zr) compared with cp-Ti, targeting to seek for the binary Ti-alloys which has the lowest C. albicans infection. Candida albicans cultures were grown on the specimens for 48 h, and colony forming units (CFUs) and real-time polymerase chain reaction (RT-PCR) were used to evaluate the biofilm formation ability. Scanning electron microscopy and confocal laser scanning microscopy confirmed the formation of C. albicans biofilm on all specimens' surfaces, such that CFU results showed Ti-Mo, Ti-Zr, Ti-Al and Ti-V have less C. albicans formed on the surfaces than cp-Ti. RT-PCR showed Ti-Zr and Ti-Cu have significantly higher C. albicans DNA concentrations than Ti-Al and Ti-V ( P < 0.05), whereas Ti-Cu has even showed a statistically higher concentration than Ti-Au, Ti-Co, Ti-In and Ti-Pt ( P < 0.05). This study confirmed that Ti-Mo, Ti-Zr, Ti-Al and Ti-V have lower the occurrence of C. albicans which might be clinically advantageous for medical devices, but Ti-Cu should be used in caution., (© The Author(s) 2020. Published by Oxford University Press.)

Aim: To investigate the null hypothesis that neither the surface conditioning (collagen, serum, saliva) of hydroxyapatite (HA) discs, nor the biofilm age (3 days vs. 21 days) has a significant effect on the cellular and matrix composition of biofilms, using Enterococcus faecalis as the model organism., Methodology: Sterile HA discs were conditioned with collagen, saliva or serum, and inoculated with E. faecalis to form 3-day and 21-day-old biofilms. Unconditioned discs served as controls. The biofilms were analysed using culture-dependent and independent (confocal microscopy and biochemical analysis) methods, to determine the colony-forming units and the biofilm matrix composition (polysaccharides and proteins), respectively. Statistical analyses were performed using appropriate parametric and nonparametric tests (P = 0.05)., Results: Collagen conditioning significantly increased the number of CFUs in the 21-day biofilms, compared to the 3-day biofilms (P < 0.05). Although the biochemical analysis revealed that surface conditioning had no significant effect on the total carbohydrate content in the 21-day biofilms, confocal microscopic analysis revealed that collagen and saliva conditioning selectively increased the polysaccharide content of 21-day biofilms, compared to the 3-day biofilms (P < 0.05)., Conclusions: The results of this study raise an important methodological concern that the substrate conditioning substances and biofilm age differentially influence the cellular and extracellular matrix components of E. faecalis biofilms., (© 2019 International Endodontic Journal. Published by John Wiley & Sons Ltd.)

The aim of the current study was to synthesize a fast-setting ion-doped calcium silicate bioceramic by the sol-gel method and to characterize its in vitro apatite-forming ability and cell viability. Calcium silicate (CS), doped calcium silicate with zinc and magnesium, with Ca/Zn molar ratios of 6.7:1 (DCS1), and 4.5:1 (DCS2), were synthesized by the sol-gel method. Matreva white MTA (WMTA, Matreva, CA, Egypt) was used as a control. The synthesized powders were characterized by x-ray diffraction. Setting time was measured using the Gilmore needle indentation technique. The in vitro apatite-forming ability of the materials was evaluated by scanning electron microscope and energy dispersive X-ray. NIH3T3-E1 cells viability was tested using MTT assay. The ion release of Ca, Si, Zn, and Mg was measured using inductive coupled plasma-optical emission spectroscopy (ICP-OES). One-way ANOVA was used to analyze setting time results. The Tukey's HSD post hoc test was used to establish significance (p < 0.001). For nonparametric data, the Kruskal-Wallis H test with Dunn's correction for post hoc comparison was used (p < 0.05). CS, DCS1, and DCS2 showed a significant decrease in setting time 33 ± 1.63 min, 28 ± 1.63 min, and 41.75 ± 2.87 min, respectively, compared to WMTA 91 ± 3.16 min (p < 0.001). DCS1 showed the highest apatite-forming ability and cell viability compared to the other groups. Ca and Si ions release decreased in both DCS1 and DCS2. The physical and biological properties of CS can be successfully improved by the sol-gel synthesis and ions doping. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 108B:56-66, 2020., (© 2019 Wiley Periodicals, Inc.)

Sutures are greatly involved in both normal craniofacial growth and developmental anomalies. Having clear parameters for defining their morphology is fundamental to properly investigate their physiological or pathological development. However, the current literature is lacking of well-defined methods for the assessment of these structures. This study performed a comprehensive microcomputed tomography (μCT) analysis of a swine model evaluating morphological variation of sutures in different skull regions. Seventy-two suture samples were removed from one swine (Sus scrofa), approximately 9-12-month-old. Each sample was analyzed with μCT in the parallel (PAR) and perpendicular (PER) plane with respect to the bone surface. Suture width (S w ), linear obliteration index (LOI), and linear interdigitation index (LII) were calculated in each of the two reference planes, and sutures were categorized in four types (S t ). Parameters were compared among the facial, craniofacial, and cranial region. Description of the main morphological parameters was provided, and differences were found between the parallel and perpendicular planes. S t varied depending on the skull region, with simple sutures more represented in the cranial region. LII in the perpendicular plane decreased from facial to craniofacial and cranial region. S w in the parallel plane decreased from facial and craniofacial to cranial region. In the swine model, the sutural width, linear interdigitation, and suture type were related to distinct skull regions. The suture type was introduced to allow a better morphological characterization of sutures as 3D structures. Clear definition of sutural parameters is important for appropriate description of these complex structures. Anat Rec, 302:2156-2163, 2019. © 2019 American Association for Anatomy., (© 2019 American Association for Anatomy.)

Reconstruction of long-bone segmental defects (LBSDs) has been one of the biggest challenges in orthopaedics. Biomaterials for the reconstruction are required to be strong, osteoinductive, osteoconductive, and allowing for fast angiogenesis, without causing any immune rejection or disease transmission. There are four main types of biomaterials including autograft, allograft, artificial material, and tissue-engineered bone. Remarkable progress has been made in LBSD reconstruction biomaterials in the last ten years., The Translational Potential of This Article: Our aim is to summarize recent developments in the divided four biomaterials utilized in the LBSD reconstruction to provide the clinicians with new information and comprehension from the biomaterial point of view., (© 2019 Published by Elsevier (Singapore) Pte Ltd on behalf of Chinese Speaking Orthopaedic Society.)

Aim of the Study: The aim of this laboratory study was to evaluate the effect of ethanol treatment on the surface roughness (S a ), nano-mechanical properties (NMP) and surface characterization of dental fiber reinforced composite (FRC) with semi-interpenetrating polymer network (IPN)., Materials and Methods: A total of 240 FRC specimens with bisphenol A-glycidyl methacrylate - triethyleneglycol dimethacrylate - Poly (methylmetahcrylate) (bis-GMA-TEGDMA-PMMA) IPN matrix system were light cured for 40 s and divided into 2 groups (L and LH). The group LH was further post-cured by heat at 95 °C for 25 min. The specimens were exposed to 99.9%, 70% and 40% for 15, 30, 60 and 120 s respectively. The treated specimens were evaluated for S a using non-contact profilometer. NMP were determined using nanoindentation technique and chemical characterization was assessed by Fourier Transform-Infrared (FTIR) spectroscopic analyses. Scanning electron microscopic (SEM) images were made to evaluate the surface topographical changes., Results: Both the L and LH group showed changes in the S a and NMP after being treated by different concentrations of ethanol and at different time interval. The highest S a was observed with L-group (0.733 μm) treated with 99.9% ethanol for 120 s. Specimens in LH-group treated with 99.9% ethanol for 120 s (1.91 GPa) demonstrated increased nano-hardness, and group treated with 40% ethanol for 120 s demonstrated increased Young's modulus of elasticity (22.90 GPa). FTIR analyses revealed changes in the intensity and bandwidth in both the L and LH groups., Conclusion: The present study demonstrated that both light-cured and heat post-cured FRC were prone for ethanol induced alteration in the surface roughness (S a ), nano-mechanical properties (NMP) and chemical characterization. The interphase between the glass fibers and the organic matrix was affected by ethanol. The changes were considerably less in magnitude in the heat post-cured FRC specimens., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Objective: To analyze effect of NaOCl+2% quaternary ammonium silane (QAS)-containing novel irrigant against bacteria impregnated inside the root canal system, and to evaluate its antimicrobial and mechanical potential of dentine substrate., Methods: Root canal was prepared using stainless steel K-files™ and ProTaper™ and subjected to manual and ultrasonic irrigation using 6% NaOCl+2% CHX, 6% NaOCl+2% QAS and saline as control. For confocal-microscopy, Raman spectroscopy and SEM analysis before and after treatment, Enterococcus faecalis cultured for 7 days. Raman spectroscopy analysis was done across cut section of gutta percha/sealer-dentine to detect resin infiltration. Indentation of mechanical properties was evaluated using a Berkovich indenter. The contact angle of irrigants and surface free energy were evaluated. Mineralization nodules were detected through Alazarin red after 14 days., Results: Control biofilms showed dense green colonies. Majority of E. faecalis bacteria were present in biofilm fluoresced red in NaOCl+2% QAS group. There was reduction of 484cm -1 Raman band and its intensity reached lowest with NaOCl+2% QAS. There was an increase in 1350-1420cm -1 intensity in the NaOCl+2% CHX groups. Gradual decrease in 1639cm -1 and 1609cm -1 Raman signal ratios were seen in the resin-depth region of 17μm>, 14.1μm> and 13.2μm for NaOCl+2% QAS, NaOCl+2% CHX and control groups respectively. All obturated groups showed an intact sealer/dentine interface with a few notable differences. 0.771 and 83.5% creep indentation distance for NaOCl+2% QAS ultrasonic groups were observed. Highest proportion of polar component was significantly found in the NaOCl+2% QAS groups which was significantly higher as compared to other groups. Mineralized nodules were increased in NaOCl+2% QAS., Significance: Favorable antimicrobial and endodontic profile of the NaOCl+2% QAS solution might suggest clinical use for it for more predictable reduction of intracanal bacteria., (Copyright © 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

The aim of this in vitro study was to evaluate the adhesion strength of two new fiber post systems (FiberSite™ Post and Cytec™ Blanco Post) cemented with two different adhesive resin cements (Panavia™ SA and Maxcem™ Elite). Root canals of sixty extracted human mandibular premolars were prepared using ProTaper Universal™ rotary files (Dentsply Sirona Endodontics, York, PA, USA). The root canals were irrigated with 5.25% sodium hypochlorite (NaOCl) during instrumentation. After root canal preparation, the canals were irrigated with 2 mL of 17% EDTA (1 min), followed by 2 mL of 5.25% (5 min) NaOCI, and 2 mL saline. The root canals were dried with paper points and divided randomly into two study groups ( n = 30) according to the type of post system: Group 1, FiberSite™ Post (MegaDental, Partanna, Italy); and group 2, Cytec™ Blanco Post (Hahnenkratt, Königsbach-Stein, Germany), with one of the two adhesive resin cements: Subgroup A, Panavia™ SA Cement Plus Automix (Kuraray, Osaka, Japan); subgroup B, Maxcem™ Elite (Kerr, Orange, CA, USA). Following thermocycling, the adhesion strength was evaluated using the push-out adhesion (bond) strength test. Fractographic analysis was performed using stereomicroscope. The data were analyzed using two-way analysis of variance ( p = 0.05). The adhesion strength values of both the posts were significantly higher when cemented with subgroup B (Maxcem™ Elite). The highest adhesion strength value was demonstrated by group 1B (FiberSite™ post cemented with Maxcem™ Elite cement). The type of post did not have a significant impact on the bond strength values for either cement material.