Microbiological and SEM-EDS Evaluation of Titanium Surfaces Exposed to Periodontal Gel: In Vitro Study

Effectiveness of mechanical and chemical decontamination methods for the treatment of dental implant surfaces affected by peri-implantitis: A systematic review and meta-analysis

OBJECTIVE

To assess which decontamination method(s) used for the debridement of titanium surfaces (disks and dental implants) contaminated with bacterial, most efficiently eliminate bacterial biofilms.

MATERIAL AND METHODS

A systematic search was conducted in four electronic databases between January 1, 2010 and October 31, 2022. The search strategy followed the PICOS format and included only in vitro studies completed on either dental implant or titanium disk samples. The assessed outcome variable consisted of the most effective method(s)-chemical or mechanical- removing bacterial biofilm from titanium surfaces. A meta-analysis was conducted, and data was summarized through single- and multi-level random effects model (p < .05).

RESULTS

The initial search resulted in 5260 articles after the removal of duplicates. After assessment by title, abstract, and full-text review, a total of 13 articles met the inclusion criteria for this review. Different decontamination methods were assessed, including both mechanical and chemical, with the most common method across studies being chlorhexidine (CHX). Significant heterogeneity was noted across the included studies. The meta-analyses only identified a significant difference in biofilm reduction when CHX treatment was compared against PBS. The remaining comparisons did not identify significant differences between the various decontamination methods.

CONCLUSIONS

The present results do not demonstrate that one method of decontamination is superior in eliminating bacterial biofilm from titanium disk and implant surfaces.

The Impact of Mechanical Debridement Techniques on Titanium Implant Surfaces: A Comparison of Sandblasted, Acid-Etched, and Femtosecond Laser-Treated Surfaces

This study evaluated the effects of various mechanical debridement methods on the surface roughness (Ra) of dental implants, comparing femtosecond laser-treated surfaces with conventionally machined and sandblasted with large-grit sand and acid-etched (SLA) implant surfaces. The fabrication of grade 4 titanium (Ti) disks (10 mm in diameter and 1 mm thick) and the SLA process were carried out by a dental implant manufacturer (DENTIS; Daegu, Republic of Korea). Subsequently, disk surfaces were treated with various methods: machined, SLA, and femtosecond laser. Disks of each surface-treated group were post-treated with mechanical debridement methods: Ti curettes, ultrasonic scaler, and Ti brushes. Scanning electron microscopy, Ra, and wettability were evaluated. Statistical analysis was performed using the Kruskal-Wallis H test, with post-hoc analyses conducted using the Bonferroni correction (α = 0.05). In the control group, no significant difference in Ra was observed between the machined and SLA groups. However, femtosecond laser-treated surfaces exhibited higher Ra than SLA surfaces (p < 0.05). The application of Ti curette or brushing further accentuated the roughness of the femtosecond laser-treated surfaces, whereas scaling reduced the Ra in SLA surfaces. Femtosecond laser-treated implant surfaces, with their unique roughness and compositional attributes, are promising alternatives in dental implant surface treatments.

Impact of Er,Cr:YSGG Laser, Sandblast, and Acid Etching Surface Modification on Surface Topography of Biodental Titanium Implants

Introduction: Several techniques have been used to modify the surface of commercially pure titanium (CPTi) implants to improve osseointegration using lasers, sandblasts, sandblasts with acid etching, and other modalities. For implant-osseointegration, surface features like chemical composition of a surface, topography, and surface energy are essential. The present comparative study aimed to compare the impact of Er,Cr:YSGG laser, sandblasting, and acid etching implant surface modifications on the surface topography, roughness, and element chemical composition of the Ti dental implant. Methods: Thirty CPTi dental implants were divided into three groups according to the surface modification (n=10 for each group): Group A: Sandblasting with acid etching (SLActive), group B: Sandblasting, and group C: Er,Cr:YSGG laser surface modifications. The modified surfaces were analyzed using scanning electron microscopy (SEM), profilometer, and energy dispersive x-ray spectrometry (EDS). Results: One-way analysis of variance (ANOVA) showed that there were significant differences in the mean values of average roughness (Ra) of the three groups (P<0.05). Tukey's post hoc test showed that the average roughness (Ra) of laser-surface modification (group C) of the implant had the highest mean value (2.30 µm) among the different groups, while sandblasted surface modification (group B) of the implant had the lowest mean value (1.39 µm). The SLActive (group A) sandblast with acid etching had a mean value of 1.63 µm. SEM analysis showed that significantly modified surface topographies and different element concentrations were found within all modified groups. Conclusion: The Er,Cr:YSGG laser irradiation increased the implant surface roughness value after implant surface modification, compared to sandblasts and sandblasts with acid etching application. The observations for the SEM-EDS analysis revealed several elements with different concentrations, which were affected by the physical-chemical characteristics of the surface modification techniques. The SEM analysis showed a significant modification in implant surface topographies of the tested groups.

Periodontopathogens Porphyromonas gingivalis and Fusobacterium nucleatum and Their Roles in the Progression of Respiratory Diseases

The intricate interplay between oral microbiota and the human host extends beyond the confines of the oral cavity, profoundly impacting the general health status. Both periodontal diseases and respiratory diseases show high prevalence worldwide and have a marked influence on the quality of life for the patients. Accumulating studies are establishing a compelling association between periodontal diseases and respiratory diseases. Here, in this review, we specifically focus on the key periodontal pathogenic bacteria Porphyromonas gingivalis and Fusobacterium nucleatum and dissect their roles in the onset and course of respiratory diseases, mainly pneumonia, chronic obstructive pulmonary disease, lung cancer, and asthma. The mechanistic underpinnings and molecular processes on how P. gingivalis and F. nucleatum contribute to the progression of related respiratory diseases are further summarized and analyzed, including: induction of mucus hypersecretion and chronic airway inflammation; cytotoxic effects to disrupt the morphology and function of respiratory epithelial cells; synergistic pathogenic effects with respiratory pathogens like Streptococcus pneumoniae and Pseudomonas aeruginosa. By delving into the complex relationship to periodontal diseases and periodontopathogens, this review helps unearth novel insights into the etiopathogenesis of respiratory diseases and inspires the development of potential therapeutic avenues and preventive strategies.

In vitro release of silver ions and expression of osteogenic genes by MC3T3-E1 cell line cultured on nano-hydroxyapatite and silver/strontium-coated titanium plates

Attempts are ongoing to improve the surface properties of dental implants by application of different coatings, aiming to enhance osseointegration, and decrease the adverse effects of titanium and its alloys used in dental implants. Coating of implant surface with hydroxyapatite (HA) is one suggested strategy for this purpose due to its high biocompatibility and similar structure to the adjacent bone. This study aimed to quantify the release of silver ions and expression of osteogenic genes by MC3T3-E1 cells cultured on nano-HA and silver/strontium (Ag/Sr)-coated titanium plates via the electrochemical deposition method. Plates measuring 10 × 10 × 0.9 mm were fabricated from Ti-6Al-4 V alloy, and polished with silicon carbide abrasive papers before electrochemical deposition to create a smooth, mirror-like surface. After applying homogenous nano-HA coatings with/without silver/strontium on the surface of the plates, the composition of coatings was confirmed by energy-dispersive X-ray spectroscopy (EDS), and their morphological properties were analyzed by scanning electron microscopy (SEM). The coated specimens were then immersed in simulated body fluid (SBF), and the concentration of released sliver ions was quantified by spectroscopy at 7-14 days. The MC3T3-E1 osteoblastic cell line was cultured in osteogenic medium for 7-14 days, and after RNA extraction and cDNA synthesis, the expression of runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), and osteopontin (OPN); osteogenic genes was quantified by polymerase chain reaction (PCR) using SYBR Green Master Mix kit. The expression of genes and the released amount of silver ions were compared between the two groups using the Mann-Whitney U test. The two groups were not significantly different regarding silver ion release at 14 days (P > 0.05). However, silver ion release was significantly higher from nano-HA coatings with silver/strontium at 7 days (P = 0.03). The difference in expression of RUNX2 (P = 0.04), OPN (P = 0.04), and OCN (P = 0.03) genes was also significant between nano-HA coating groups with and without silver/strontium at 7 days, and the expressions were higher in nano-HA with silver/strontium group, but this difference was not significant at 14 days. Addition of silver and strontium to specimens coated with nano-HA increased the release of silver ions within the non-toxic range, and enhanced the expression of osteogenic genes particularly after 7 days.

Antimicrobial efficiency and cytocompatibility of different decontamination methods on titanium and zirconium surfaces

OBJECTIVES

The purpose of this study was to investigate the efficiency of different implant-decontamination methods regarding biofilm modification and potential cytotoxic effects. Therefore, the amount of biofilm reduction, cytocompatibility, and elementary surface alterations were evaluated after decontamination of titanium and zirconium surfaces.

MATERIAL AND METHODS

Titanium and zirconium disks were contaminated with a newly developed high-adherence biofilm consisting of six microbial species. Decontaminations were performed using titanium curette, stainless steel ultrasonic scaler (US), glycine (GPAP) and erythritol (EPAP) powder air-polishing, Er:YAG laser, 1% chlorhexidine (CHX), 10% povidone-iodine (PVI), 14% doxycycline (doxy), and 0.95% NaOCl solution. Microbiologic analysis was done using real-time qPCR. For assessment of cytocompatibility, a multiplex assay for the detection of cytotoxicity, viability, and apoptosis on human gingival fibroblasts was performed. X-ray photoelectron spectroscopy (XPS) was used to evaluate chemical alterations on implant surfaces.

RESULTS

Compared with untreated control disks, only GPAP, EPAP, US, and Er:YAG laser significantly reduced rRNA counts (activity) on titanium and zirconium (p < .01), whereas NaOCl decreased rRNA count on titanium (p < .01). Genome count (bacterial presence) was significantly reduced by GPAP, EPAP, and US on zirconium only (p < .05). X-ray photoelectron spectroscopy analyses revealed relevant re-exposure of implant surface elements after GPAP, EPAP, and US treatment on both materials, however, not after Er:YAG laser application. Cytocompatibility was impaired by CHX, PVI, doxy, and NaOCl. CHX and PVI resulted in the lowest viability and doxy in the highest apoptosis.

CONCLUSIONS

Within the limits of this in vitro study, air-polishing methods and ultrasonic device resulted in effective biofilm inactivation with surface re-exposure and favorable cytocompatibility on titanium and zirconium. Chemical agents, when applied on implant surfaces, may cause potential cytotoxic effects.

SEM-EDX Analysis of Metal Particles Deposition from Surgical Burs after Implant Guided Surgery Procedures

The preparation of the implant site in guided surgery procedure takes place without irrigation, which could lead to increased friction of the drills with the formation and release of debris or metal particles. The presence of metal particles in the peri-implant tissue could represent a trigger for macrophage activity, bone resorption processes, and consequent implant loss. According to the guided surgical protocol, the study aimed to evaluate the presence of metal particles deposited during implant site preparation. Twenty-five adult porcine ribs from the same adult individual were chosen due to their trabecular bone structure, similar to facial bones. The samples were all 8 cm (length) × 3 cm (depth) × 2 cm (width) and were further subdivided to obtain 50 elements of 4 cm × 3 cm × 2 cm. Plexiglass was used to create structures such as surgical guides so that their function could be mimicked, and the guided implant site preparation sequence could be performed with them. The drill kit used in this study is a guided surgery drill kit characterized by high wear resistance, high yield strength, and good corrosion resistance. This same kit was used 50 times in this way to prepare 50 different implant sites and evaluated at different edges and number of preparation (T0-neutral edge, T1-1 full preparation, T2-10, T3-20, T4-30, T5-40, and T6-50) by SEM-EDX to assess the presence of any metal deposition. The presence of metal residues in the implant site increased according to the cycles of use of the drills. We have observed that in the first three groups, there is no presence of metals. This is evident in groups T3 and T4. Finally, the presence of metal residues becomes significant in the study’s last two groups of samples. The study highlighted how the lack of irrigation in the work site leads the deposition of metal particles and in addition to a reduction in the efficiency of the drills, resulting in less precise cutting, altering the shape of the prepared site, and, lastly, reducing the primary stability of the implants.

3D Printed Buccal Films for Prolonged-Release of Propranolol Hydrochloride: Development, Characterization and Bioavailability Prediction

Gelatin-polyvinylpyrrolidone (PVP) and gelatin-poly(vinyl alcohol) (PVA) mucoadhesive buccal films loaded with propranolol hydrochloride (PRH) were prepared by semi-solid extrusion 3D printing. The aim of this study was to evaluate the effects of the synthetic polymers PVP and PVA on thermal and mechanical properties and drug release profiles of gelatin-based films. The Fourier-transform infrared spectroscopy showed that hydrogen bonding between gelatin and PVP formed during printing. In the other blend, neither the esterification of PVA nor gelatin occurred. Differential scanning calorimetry revealed the presence of partial helical structures. In line with these results, the mechanical properties and drug release profiles were different for each blend. Formulation with gelatin-PVP and PRH showed higher tensile strength, hardness, and adhesive strength but slower drug release than formulation with gelatin-PVA and PRH. The in silico population simulations indicated increased drug bioavailability and decreased inter-individual variations in the resulting pharmacokinetic profiles compared to immediate-release tablets. Moreover, the simulation results suggested that reduced PRH daily dosing can be achieved with prolonged-release buccal films, which improves patient compliance.

Assessment of Oral Microbiome Changes in Healthy and COVID-19-Affected Pregnant Women: A Narrative Review

During pregnancy, there are several metabolic changes and an alteration in the composition of microorganisms that inhabit the oral cavity, with an increase in pathogenic bacteria that promote the onset of gingival diseases. This review is based on research in reference to the PICO model (Problem/Intervention/Comparison/Outcome), related to changes in the oral microbiome of pregnant women and possible oral consequences in patients with COVID-19. The results showed a growth of some pathogenic bacteria in pregnant women, including Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum, and the selective growth of the Prevotella intermedia, Porphyromonas gingivalis and Tannerella species, probably due to the fact that these bacteria use progesterone as a source of nutrition. These same bacteria are implicated in the development of periodontal disease. Periodontal pockets have bidirectional interactions between the oral cavity and the systemic circulatory system through the peripheral gingival blood vessels. The affinity of the SARS-CoV-2 virus to specific membrane receptors is now clear, and could involve the internal and external epithelial lining or the fibroblasts of the periodontal ligament. According to the results of the present review, the control of oral microbiome changes during pregnancy would be welcomed. The use of probiotics could help clinicians manage pregnant patients, reducing inflammatory indexes. Future studies should focus not only on changes in the level of the oral microbiome in pregnancy or the correlation between periodontal disease and COVID-19, but also on oral changes induced by both clinical situations.

Professional Mechanical Tooth Cleaning Method for Dental Implant Surface by Agar Particle Blasting

Oral dysfunction due to peri-implantitis and shortened life of implants has become a major concern. Self-care and removal of oral biofilms by professional mechanical tooth cleaning (PMTC) are indispensable for its prevention. However, if the surface roughness of the implant is increased, it may result in the adhesion of biofilm in the oral cavity. Therefore, the PMTC method can serve for long-term implant management. Calcium carbonate (CaCO₃) has been used as a cleaning method for implant surfaces; however, there is concern that the implant surface roughness could increase due to particle collision. Therefore, in this study, to establish a blasting cleaning method that does not adversely affect the implant surface, a new blasting cleaning method using agar particles was devised and its practical application examined. When the simulated stains were blasted with white alumina (WA) abrasive grains and CaCO₃ particles, the simulated stains were almost removed, the surface roughness changed to a satin-finished surface—which was thought to be due to fine scratches—and the surface roughness increased. Most of the simulated stains were removed on the surface of the sample blasted with glycine particles and agar particles. Conversely, the gloss of the sample surface was maintained after cleaning, and the increase in surface roughness was slight.

Development and Evaluation of Thermosensitive Hydrogels with Binary Mixture of Scutellariae baicalensis radix Extract and Chitosan for Periodontal Diseases Treatment

Scutellaria baicalensis root displays anti-inflammatory and antibacterial properties due to the presence of flavonoids, particularly baicalin, baicalein, and wogonin. Our work aimed at developing thermosensitive hydrogels containing a binary mixture of S. baicalensis radix lyophilized extract and chitosan as a novel approach for periodontal diseases treatment. Two types of chitosan were employed in preliminary studies on binary mixtures with S. baicalensis radix lyophilized extract standardized for baicalin, baicalein, and wogonin. Thermosensitive hydrogels were prepared of poloxamer 407, alginate sodium, and cellulose derivatives and evaluated in terms of rheological and mucoadhesive behavior. The presence of chitosan altered the release profile of active compounds but did not affect their in vitro permeation behavior in PAMPA assay. The synergistic effects of S. baicalensis radix lyophilized extract and chitosan toward ferrous ion-chelating activity, inhibition of hyaluronidase, and pathogen growth were observed. The thermosensitive gelling system showed shear-thinning properties, gelation temperature between 25 and 27 °C, and favorable mucoadhesiveness in contact with porcine buccal mucosa, which was enhanced in the presence of binary mixture of S. baicalensis radix extract and chitosan. The release tests showed that baicalin and baicalein were liberated in a prolonged manner with a fast onset from hydrogel formulations.

Problems with identifying and distinguishing salivary streptococci: a multi-instrumental approach

Aim: The purpose of this study was to create an alternative protocol for the DNA-based identification of salivary microbiota focused on the distinguishing of Streptococcus species. Materials & methods: Salivary bacteria were identified using 16S rDNA sequencing and proteins and lipids profiling using MALDI-TOF/MS as well as FTIR analysis. Results: Most of the isolates belonged to streptococci - mostly the salivarious group indistinguishable by the molecular technique. In turn, MALDI analysis allowed for their fast and reliable classification. Although FTIR spectroscopy demonstrated the correct species classification, the spectra interpretation was time consuming and complicated. Conclusion: MALDI-TOF/MS demonstrated the biggest effectiveness in the identification and discrimination between the salivary streptococci, which could be easily incorporated in the workflow of routine microbiological laboratories.

Subinhibitory Antibiotic Concentrations Enhance Biofilm Formation of Clinical Enterococcus faecalis Isolates

Enterococcus faecalis is a microorganism that can be found in the oral cavity, especially in secondary endodontic infections, with a prevalence ranging from 24-70%. The increase in the ability to form biofilms in the presence of subinhibitory antibiotic concentrations is a phenomenon that is observed for a wide variety of bacterial pathogens and is associated with increased resistance. In this study, therefore, six E. faecalis isolates from an endodontic environment and two control strains were exposed to subinhibitory concentrations of Penicillin G, Amoxicillin, Doxycycline, Fosfomycin, Tetracycline and Vancomycin and examined for their biofilm formation abilities. The minimum inhibitory concentration (MIC) was determined for all E. faecalis isolates. A culture of the isolate was mixed with a serial dilution series of the respective antibiotic, incubated overnight and the biofilm formation was analyzed using a microtiter plate assay. All isolates were able to form biofilms in the absence of an antibiotic. A significant increase in biofilm formation of up to more than 50% was found in the isolates exposed to subinhibitory concentrations of various antibiotics. Most isolates showed a significant increase in Fosfomycin (7/8), Doxycycline (6/8) and Tetracycline (6/8). Three endodontic isolates showed a significant increase in five of the antibiotics examined at the same time. On exposure to Vancomycin, three endodontic isolates and the two control strains showed an increase. The increase in the ability to form biofilms extended over a concentration range from 1/2 to 1/64 of the MIC concentration. Antibiotics may reach certain niches in the oral cavity at subinhibitory concentrations only. This can increase the biofilm formation by enterococci, and in turn lead to decreased susceptibility of these taxa to antibiotics.

Photocatalytic enhancement of antibacterial effects of photoreactive nanohybrid films in an in vitro Streptococcus mitis model

OBJECTIVE

Bacterial adhesion and colonization on implanted devices are major etiological factors of peri-implantitis in dentistry. Enhancing the antibacterial properties of implant surfaces is a promising way to reduce the occurrence of inflammations. In this in vitro study, the antibacterial potential of two nanocomposite surfaces were investigated, as possible new materials for implantology.

MATERIAL AND METHODS

The structural and photocatalytic properties of the TiO₂ and Ag-TiO₂ (with 0.001 wt% plasmonic Ag content) photocatalyst containing polymer based composite layers were also studied and compared to the unmodified standard sandblasted and acid etched Ti discs (control). The presence of visible light induced reactive oxygen species was also verified and quantified by luminol based chemiluminescence (CL) probe method. The discs with adhered Streptococcus mitis were illuminated for 5, 10 and 15 min. The antibacterial effect was determined by the metabolic activities of the adhered and proliferated bacterial cells and protein assay at each time point.

RESULTS

The Ag-TiO₂ containing surfaces with obvious photocatalytic activity eliminated the highest amount of the metabolically active bacteria, compared to the control discs in the dark, after 15 min illumination.

CONCLUSIONS

The plasmonic Ag-enhanced and illuminated surface exhibits significantly better antibacterial activity under harmless visible light irradiation, than the control Ti or TiO₂ containing copolymer. The studied surface modifications could be promising for further, more complex investigations associated with dental research on infection prevention in connection with oral implantation.

Debonding and Clean-Up in Orthodontics: Evaluation of Different Techniques and Micro-Morphological Aspects of the Enamel Surface

There is currently no consensus on the best way to remove adhesive remnants from teeth following debonding. The main objective of this study is to evaluate and compare the effectiveness of four adhesive resin removal (clean-up) techniques, performed with or without the use of an operative microscope. Forty human teeth were duplicated using an epoxy resin for impregnation. Brackets were bonded to teeth and debonded from teeth. Then, the samples were randomly divided into two equal groups-the naked eye group and the magnification group-and further subdivided into four equal subgroups, in order to compare the different techniques used for the clean-up. Each subgroup was formed of five natural teeth with the respective pre- and post-bonding replicas. Macro- and micro-analysis by means of a stereomicroscope and scanning electron microscopy evaluated, qualitatively and quantitatively, the adhesive remnant index and the damage index of the enamel. Overall, the magnification improved the removal of resins compared to the naked eye (p < 0.001), and the use of magnification constantly reduced resin residual and surface damage. Enamel damage and adhesive residual from the clean-up procedures represent an ascertained risk in orthodontics. The use of a magnification system improves the quality of debonding and clean-up techniques in a significant way.

Effects of a derivative of reutericin 6 and gassericin A on the biofilm of Streptococcus mutans in vitro and caries prevention in vivo

It is known that Streptococcus mutans (S. mutans) is the leading cariogenic pathogen. Recently, an increasing number of antimicrobial peptides (AMPs) have been brought into consideration as anti-caries agents. Here, we designed and synthesized an AMP derived from reutericin 6 and/or gassericin A, named LN-7, and explored its effect on biofilm of S. mutans UA159 in vitro and development of dental caries in vivo. Antibacterial assays showed that LN-7 was more active against S. mutans (3.2 μM) than many peptide-based agents, capable of killing other types of Streptococci in oral cavity. In addition, LN-7 presented fast killing kinetics, with more than 97% S. mutans killed within 5 min. The mechanism of the antimicrobial activity mainly lies on the disruption of bacterial membrane. Effects of LN-7 on the biofilm formation and the viability of preformed biofilm were quantified by crystal violet staining, which showed that LN-7 could effectively inhibit the biofilm accumulation of S. mutans. Moreover, the biofilm of S. mutans treated with LN-7 displayed notable changes in bacterial viability and morphology, observed by confocal laser scanning microscopy and scanning electron microscopy. In addition, topical oral treatment with LN-7 could suppress the development of dental caries in vivo, reducing the occurrence of severe dental lesion in a rodent model. These results reveal a new peptide-based agent as a topical treatment for dental caries, opening the door to clinical studies to explore its potential for caries prevention.

Silk Fibroin-Based Hybrid Nanostructured Coatings for Titanium Implantable Surfaces Modification

This study proposes the development of new architectures that combine nanostructured titanium surface and biodegradable polymers as a promising approach to achieve a better performance after bioactive agent incorporation. The silk fibroin protein that was extracted from silkworm Bombyx mori cocoons is important due to the remarkable characteristics, such as biocompatibility, good mechanical properties, adjustable degradation and drug stabilizing capabilities. The titanium substrate was firstly nanostructurated with TiO2 nanotubes and then coated with silk fibroin using electrospinning and electrochemical deposition. The deposited silk film ability to become a bioactive implant coating with antibacterial properties after the encapsulation of the active agents such as CeO2 was investigated. Important features of the new implant coating were analysed: surface properties, electrochemical stability in physiological simulated electrolytes, and antibacterial action against Escherichia coli. The obtained results indicate that silk fibroin bioactive layers are a potential candidate for regenerative medicine.

Pre-Implantation Mouse Embryos Cultured In Vitro under Different Oxygen Concentrations Show Altered Ultrastructures

Assisted Reproductive Technologies routinely utilize different culture media and oxygen (O2) concentrations to culture human embryos. Overall, embryos cultured under physiological O2 tension (5%) have improved development compared to embryos cultured under atmospheric O2 conditions (20%). The mechanisms responsible for this remain unclear. This study aimed to evaluate the effect of physiologic (5%) or atmospheric O2 (20%) tension on the microscopic ultrastructure of pre-implantation mouse embryos using Transmission Electron Microscopy (TEM). Embryos flushed out of the uterus after natural mating were used as the control. For use as the control, 2-cells, 4-cells, morulae, and blastocysts were flushed out of the uterus after natural fertilization. In vitro fertilization (IVF) was performed using potassium simplex optimized medium (KSOM) under different O2 tensions (5% and 20%) until the blastocyst stage. After collection, embryos were subjected to the standard preparative for light microscopy (LM) and TEM. We found that culture in vitro under 5% and 20% O2 results in an increase of vacuolated shaped mitochondria, cytoplasmic vacuolization and presence of multi-vesicular bodies at every embryonic stage. In addition, blastocysts generated by IVF under 5% and 20% O2 showed a lower content of heterochromatin, an interruption of the trophectodermal and inner cell mass cell membranes, an increased density of residual bodies, and high levels of glycogen granules in the cytoplasm. In conclusion, this study suggests that in vitro culture, particularly under atmospheric O2 tension, causes stage-specific changes in preimplantation embryo ultrastructure. In addition, atmospheric (20%) O2 is associated with increased alterations in embryonic ultrastructure; these changes may explain the reduced embryonic development of embryos cultured with 20% O2.

The effects of decontamination methods of dental implant surface on cytokine expression analysis in the reconstructive surgical treatment of peri-implantitis

The aim of this trial was to analyze the effect of implant surface decontamination procedures combined with reconstructive surgical treatment (RST) of peri-implantitis on gene expression levels of selected biomarkers in peri-implant crevicular fluid (PICF). Forty patients diagnosed with peri-implantitis were treated with RST + decontamination of the implant surface using sterile saline and ozone therapy (ozone group) or sterile saline alone (control group). The gene expression levels of interleukin (IL)-6, IL-8, IL-17, vascular endothelial growth factor (VEGF), sclerostin (SOST) and osteoprotegerin (OPG) were evaluated by qPCR analysis at baseline and 6-month follow-up. Changes in cytokine mRNA expression levels were analyzed and compared with clinical/radiographic parameters. Both decontamination methods lead to the downregulations of the selected gene expressions. Ozone group showed significantly higher clinical attachment level (CAL) and radiographic defect fill (DF) values at 6 months compared to the control group (p = 0.026 and p = 0.011). The downregulation of SOST levels was significantly associated with probing depth reduction and radiographic DF (p < 0.05). Implant surface decontamination procedures applied with the RST contribute to a notable reduction in immuno-inflammatory response. The additional use of ozone therapy could have favorable effects in anti-infective regimens of peri-implantitis therapy. SOST, which was found to have significant relationship with both clinical and radiographic outcomes, could be a valuable indicator for the progression of peri-implantitis and may aid the development of new therapeutic strategies for bone gain in the RST of peri-implantitis.

Preparation, Microstructure, Mechanical Properties and Biocompatibility of Ta-Coated 3Y-TZP Ceramic Deposited by a Plasma Surface Alloying Technique

A Ta coating has been successfully fabricated on the surface of zirconia polycrystals ceramic (3 mol% yttria, 3Y-TZP) by a plasma surface alloying technique. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results showed that a α-Ta coating with a continuous and compact surface morphology which consisted of a deposited layer with a thickness of 390 nm and a diffusion layer with a thickness of 200 nm covered the 3Y-TZP. Due to the effect of inhabitation the t→m transformation by the deposited Ta coating, the biaxial flexural strength caused by the phase transformation during hydrothermal aging is reduced e.g. p < 0.05 after 20 h and/or 100 h. In addition, the Ta coating shows non-cytotoxicity and improved proliferation ability of osteoblasts.

Commercial oral hygiene products and implant collar surfaces: Scanning electron microscopy observations

BACKGROUND

The use of medicated mouthwashes and gels in the home care maintenance of dental implants is controversial due to the possibility of residue deposition on the implant collar. The aim of this in vitro study was to analyse, by means of scanning electron microscopy (SEM), the amount of residues on dental implant collars treated with various commercial home dental care products.

METHODS

Gel and mouthwash products were tested on 10 implants. The gels included sodium fluoride, amine fluoride, and sodium hyaluronate products. The mouthwashes tested contained triclosan, nimesulide, stannous fluoride, amine fluoride, and hexetidine-chlorobutanol. The SEM observations were performed at different magnifications in double modality SE (secondary electrons) and BSE (backscattered electrons) to qualitatively assess any residual products. The image quantitative analysis was performed by Image J^® software to assess areas occupied by residuals. All results were analysed by the same researcher with experience in electron microscopy.

RESULTS

The fluoride-based gel products left wider areas occupied by residuals than the mouthwash products. In particular the fluoride-based and hyaluronate products left the highest amount of residues. Among mouthwashes, fluoride-based and triclosan products showed the highest amount of residuals deposition.

DISCUSSION

Oral hygiene procedures and related professional products are fundamental to the prevention, treatment, and control of microorganisms. In the case of implants, mechanical and chemical plaque control strategies are even more important since the potentially harmful biofilm covers abiotic titanium surfaces. In situ fixture maintenance is crucial for dental implant therapy success. Correct recommendation of home care products for bacterial control is fundamental to the health of implants and their surrounding tissues.

CONCLUSIONS

Data from this experimental study showed that home care commercial products in gel formulation, especially those containing fluoride, leave more residuals on titanium smooth surfaces than mouthwash products. The longer permanence of the products may lead to a more effective plaque control than other products.

In Vitro Evaluation of Bacterial Adhesion and Bacterial Viability of Streptococcus mutans, Streptococcus sanguinis, and Porphyromonas gingivalis on the Abutment Surface of Titanium and Zirconium Dental Implants

Objective

To evaluate the in vitro adherence and viability of 3 bacterial species Streptococcus mutans (ATCC 25175), Streptococcus sanguinis (ATCC 10556), and Porphyromonas gingivalis (ATCC 33277) on the surfaces of dental implants of titanium, zirconium, and their respective fixing screws.

Methods

Two analysis groups were formed: group 1 with 3 titanium pillars and group 2 with 3 zirconium pillars, each with their respective fixing screws. Each of these groups was included in tubes with bacterial cultures of Streptococcus mutans (ATCC 25175), Streptococcus sanguinis (ATCC 10556), and Porphyromonas gingivalis (ATCC 33277). These samples were incubated at 37°C under anaerobic conditions. Bacterial adherence was assessed by measurement of the change in colony-forming units (CFU), and bacterial viability was evaluated with the colorimetric test of 3-(4,5-dimethylthiazol-2)-2,5 diphenyl tetrazolium bromide (MTT).

Results

The bacterial adhesion in the titanium abutments was higher for Streptococcus mutans (190.90 CFU/mL), and the viability was greater in Porphyromonas gingivalis (73.22%). The zirconium abutment group showed the highest adherence with Streptococcus mutans (331.82 CFU/mL) and the highest bacterial viability with the S. sanguinis strain (38.42%). The titanium fixation screws showed the highest adhesion with S. sanguinis (132.5 CFU/mL) compared to the zirconium fixation screws where S. mutans had the highest adhesion (145.5 CFU/mL). The bacterial viability of S. mutans was greater both in the titanium fixation screws and in the zirconium fixation screws 78.04% and 57.38%, respectively.

Conclusions

Our results indicate that there is in vitro bacterial adherence and viability in both titanium abutments and zirconium abutments and fixation screws for both. Streptococcus mutans is the microorganism that shows the greatest adherence to the surfaces of both titanium and zirconium and the fixing screws of the latter. On the contrary, bacterial viability is greater on the titanium abutments with P. gingivalis than on the zirconium abutments with S. sanguinis. With respect to the fixation screws, in both cases, the viability of S. mutans was greater with respect to the other bacteria. In general, the titanium abutments showed less adherence but greater bacterial viability.