Microbiological and Imaging-Based Evaluations of Photodynamic Therapy Combined with Er:YAG Laser Therapy in the In Vitro Decontamination of Titanium and Zirconia Surfaces.

The oral cavity's soft and hard tissues create a conducive environment for microbial proliferation and biofilm development, facilitating the colonization of prosthodontic and implant materials such as titanium (Ti) and zirconia (Zr). This study aimed to compare the efficacy of conventional decontamination methodologies (i.e., chemical and mechanical, using 0.12% digluconate chlorhexidine (CHX) solution-treatment and airflow) to adjunctive laser-based interventions on Ti and Zr substrates inoculated with Staphylococcus (S.) aureus ATCC 25923. Additionally, this investigation sought to elucidate the impact of these treatments on temperature variations and surface integrity, analyzing the laser irradiation effects on these prevalent dental materials. Experimental configurations were delineated for both Ti and Zr samples across four groups: (1) a conventional treatment group (CV); (2) a photodynamic therapy group (PDT); (3) an Er:YAG laser treatment group (Er); (4) a combined PDT and Er:YAG treatment group (PDTEr). Also, a negative control group (C) that received no treatment was considered. The decontamination of the inoculated disc samples was evaluated by quantifying the microbial colonies in colony-forming units per milliliter (CFU/mL). Temperature variations on the surface of the samples were determined during laser treatments. Surface modifications were investigated using scanning electron microscopy (SEM) and optical coherence tomography (OCT). For statistical analysis, Fisher 95% confidence intervals, Hsu's MCB method, and the Kruskal-Wallis test were applied. With regard to the 105 CFU/mL of the negative control group, results indicated average values equal for each study group to (1) 2.66 CFU/mL for Ti and 2 CFU/mL for Zr for the CV group; (2) 0.33 CFU/mL for Ti and 1 CFU/mL for Zr for the PDT group; (3) 1.25 CFU/mL for Ti and 0 CFU/mL for Zr for the Er group; (4), and 0 CFU/mL for both Ti and Zr for the PDTEr group. Therefore, the combined PDT and Er:YAG treatment (PDTEr) and the singular PDT modality outperformed conventional decontamination methods in eradicating S. aureus biofilms from both Ti and Zr surfaces. Notably, the PDTEr regime achieved a comprehensive elimination of microbial colonies on treated substrates. Surface examination employing OCT demonstrated discernible alterations in the surface morphology of samples subjected to Er:YAG and combined PDT and Er:YAG treatments. Temperature checks during treatments showed no major changes, suggesting the applied laser methods are safe. In conclusion, PDTEr and PDT eliminated bacteria more effectively, but Zr surfaces were more resilient, making them better for microbe-controlling applications. Also, the study demonstrated that the (less costly but lower resolution) OCT method can replace SEM for such investigations.

Human Periapical Odontogenic Granulomas: Aspects of Microvessel Density (MVD), Heterogeneity of Blood Vessels and Mast Cells Density (MCD).

Periapical odontogenic granulomas are among the most encountered pathology that involve the alveolar bone, with severe consequences such as bone resorption, the presence of inflammatory infiltrate and the formation of abnormal vascularization. The present study aimed to quantify the existence of the microvessel density (MVD), mast cell density (MCD) and heterogeneity of the encountered blood vessels. A total of 37 patients diagnosed with odontogenic periapical granulomas were included, and the gender distribution, age and localization of the pathological lesions was assessed. After the surgical removal of the periapical odontogenic granuloma, the collected tissue was fixed in 10% buffered formalin. Primary processing, morphological analysis and immunohistochemical staining was performed in order to characterize the altered tissue. The results outlined the presence of a high number of mast cells, especially in the area of the inflamed tissue; the high heterogeneity of the blood vessels; and increased MVD with positive CD34. The conclusions of the study focus on the key role of the mast cells and their implication in the initiation and development of the angiogenesis process, triggering the inflammatory response of the host. Nevertheless, periapical odontogenic granulomas develop as an inflammatory response to the interaction between the host's immune system and microbial invasion.

Associated Bacterial Coinfections in COVID-19-Positive Patients.

Background and Objectives: The aim of this study was to identify specific rhino- and oropharyngeal microbiological pathogens as well as associated comorbidities that favor SARS-CoV-2 infection and corelate them. Materials and Methods: This prospective clinical study enrolled 61 patients (28 COVID-19-positive and 33 controls) who were tested for other comorbidities and co-existence of associated oral pathogenic microbiota. Results: A total of 247 bacterial isolates were identified in the bacterial cultures in both groups. Viral hepatitis type A was more prevalent in the COVID-19-positive group (p = 0.026), as was the presence of oral candidiasis (p = 0.006). In the control group, a moderate direct relationship was observed between the Beta hemolytic streptococcus group G and dermatitis, and strong direct relationships were observed between the Beta hemolytic streptococcus group G and external otitis, Streptococcus pyogenes and dental alveolitis, and Streptococcus pyogenes and chronic lymphocytic leukemia. In the test group, strong direct relationships were observed between Hemophilus influenzae and pulmonary thromboembolism; Staphylococcus aureus and autoimmune thyroiditis; post-viral immunosuppression, chronic coronary syndrome, and hypernatremia; Beta hemolytic streptococcus group C and rheumatoid polyneuropathy; Beta hemolytic streptococcus group G and hyperkalemia, hypothyroidism, secondary anemia, and splenomegaly; and active oral candidiasis and SARS-CoV-2 viral pneumonia. The following relationships were strong, but inverse: Beta hemolytic streptococcus group G and acute respiratory failure, and active oral candidiasis and SARS-CoV-2 viral bronchopneumonia. Conclusions: Briefly, COVID-19-positive patients have the predisposition to build up associated comorbidities and coinfections, which can be the expression of the immune burden that this virus generates to the host.

Attitude of Romanian Medical Students and Doctors toward Business Ethics: Analyzing the Influence of Sex, Age, and Ethics Education.

This study investigated the attitude of Romanian medical students and doctors toward business ethics by measuring the preference for a particular ethical philosophy, namely, the preference for Machiavellianism, moral objectivism, social Darwinism, ethical relativism, and legalism. At the same time, this study aimed to explore the influence of sex, age, and ethics education on the attitude toward business ethics. The data collection was performed using a voluntary self-administered online survey including the Attitudes Toward Business Ethics Questionnaire (ATBEQ) instrument. Our findings show that the values based on which Romanian medical students and doctors make business decisions belong predominantly to the moral objectivism philosophy, which is grounded on rational actions based on a set of objective moral standards.

Heterogeneity of Blood Vessels and Assessment of Microvessel Density-MVD in Gingivitis.

Gingivitis is a very common oral disease highly prevalent in adults that, if left untreated, can progress to periodontitis. It involves a complex and slow interaction between the host response and the oral microbiome represented by the dental plaque. The inflammation of the gingiva is associated with the activation of pathological angiogenesis and the existence of a high number of newly formed blood vessels quantified as microvessel density (MVD). The present study includes a number of 51 gingival biopsies from patients with different gingival indexes (GI): GI = 0, n = 12; GI = 1, n = 15; GI = 2, n = 16; and GI = 3, n = 8, processed and stained with the routine hematoxylin-eosin method. The inflammatory infiltrate was scored, the blood vessels were detected with anti-CD34 antibody, and MVD was determined. Inflammatory changes were observed in 39 of the 51 cases included in our study. CD34 + vessels with normal morphological appearance were observed in all 12 cases of health gingiva. In cases of inflammatory lesions, the morphology of the blood vessels showed changes with the evolution of gingival lesions. In severe inflammation, a particular aspect was observed in the vessels, such as the presence of the phenomenon of intussusception. MVD increases with the severity of gingival lesions, with the highest density being observed in severe inflammation.

A Comparative Analysis Regarding the Osseointegration of Immediate Loaded Implants Using Two Different Implant Site Preparations: Erbium:Yttrium-Aluminum-Garnet Laser Versus Surgical Conventional Way-An In Vivo and Histological Animal Study.

Objective: The aim of the study is to evaluate the possibility of preparing the implant site using the erbium:yttrium-aluminum-garnet (Er:YAG) laser scanner prototype and to reduce and/or eliminate time between primary (mechanical) stability and secondary (biological) stability, looking to the immediate occlusal loading in a single implant. Background: A prerequisite for successful osseointegration is the establishment of direct bone-to-implant contact without interposition of nonbone or connective tissue. In recent years, the use of laser radiation was presented as an alternative/adjunctive treatment for bone tissue ablation due to vaporization of the tissues in the absence of a smear layer. Methods: The experimental protocol included six minipigs, which underwent tooth extraction, followed (after 2 months) by implant bed preparation in two methods: using a conventional bur kit and using an Er:YAG laser scanner (X runner) protocol. Four implants were placed in positions 34, 37, 44, and 47 on each animal. The animals underwent the second surgical procedure for bone sample collection (including the implant) before their sacrifice at 45-60-90-120 days. The newly formed bone was evaluated on the bone samples using histological examination and quantitative evaluations of different histological parameters based on microscopical analysis. Results: The results that we obtained allow some interesting comparison in terms of different bone composition, depending on the method of implant site preparation and on healing periods. Moreover, it was possible to compare the bone composition, at different time stages, of implant sites prepared in the same way. Conclusions: Our research allowed us to demonstrate that the use of Er:YAG laser compared with traditional drill leads to the presence of a greater share of lamellar bone and a lower necrotic share in the implant site. We also showed the possibility of applying immediate occlusal loading on an in vivo animal model.

Osteogenic Potential of Bovine Bone Graft in Combination with Laser Photobiomodulation: An Ex Vivo Demonstrative Study in Wistar Rats by Cross-Linked Studies Based on Synchrotron Microtomography and Histology.

BACKGROUND: Alveolar bone defects are usually the main concern when planning implant treatments for the appropriate oral rehabilitation of patients. To improve local conditions and achieve implant treatments, there are several methods used for increasing bone volume, among which one of the most successful, versatile, and effective is considered to be guided bone regeneration. The aim of this demonstrative study was to propose an innovative analysis protocol for the evaluation of the effect of photobiomodulation on the bone regeneration process, using rat calvarial defects of 5 mm in diameter, filled with xenograft, covered with collagen membrane, and then exposed to laser radiation. METHODS: The animals were sacrificed at different points in time (i.e., after 14, 21, and 30 days). Samples of identical dimensions were harvested in order to compare the results obtained after different periods of healing. The analysis was performed by cross-linking the information obtained using histology and high-resolution synchrotron-based tomography on the same samples. A comparison was made with both the negative control (NC) group (with a bone defect which was left for spontaneous healing), and the positive control (PC) group (in which the bone defects were filled with xenografts and collagen membrane without receiving laser treatment). RESULTS: We demonstrated that using photobiomodulation provides a better healing effect than when receiving only the support of the biomaterial. This effect has been evident for short times treatments, i.e., during the first 14 days after surgery. CONCLUSION: The proposed analysis protocol was effective in detecting the presence of higher quantities of bone volumes under remodeling after photobiomodulation with respect to the exclusive bone regeneration guided by the xenograft.

Quantitative assessment of rat bone regeneration using complex master-slave optical coherence tomography.

BACKGROUND: The need for hard and soft tissues in oral implantology determined the development of methods and techniques to increase bone volume and their quality with different alternative materials used as substituents of patient's natural bone. In addition, laser radiation can be used to accelerate the repair of fractures and to produce an increased volume of formed callus, as well as an increased bone mineral density. METHODS: The aim of this work is to evaluate the capability of an in-house developed multimodal complex master slave (CMS) enhanced swept source (SS) optical coherence tomography (OCT) imaging instrument to analyze the increase in the quantity and the improvement of the quality of newly-formed bone using low level laser therapy (LLLT). Bone formation is quantitatively assessed in 5 mm cylindrical defects made in the calvaria part of the skull of living rats. Samples are divided in three study groups: A, a negative control group, for which the natural healing process of the defect is investigated; B, a positive control group, for which bovine graft is used to stimulate bone formation, and C, a study group, in which bovine graft is added to the created defects and LLLT is applied throughout the entire healing period. The animals are sacrificed after 14, 21, and 30 days, and the samples are imaged using the multimodal CMS/SS-OCT instrument. RESULTS: The method allows for the simultaneous monitoring of the bone tissue via two perpendicular cross-sections and nine en-face images taken at adjustable depths into the sample. A global image with course axial resolution allows for the positioning of the field-of-view of the system on the area of interest on the tissue. The quantitative assessment of the process of bone formation is completed using the differences in brightness between the native bone, the artificial bone graft, and the newly-formed bone. CONCLUSIONS: Group C is demonstrated to have a higher volume of newly-formed bone than Group B, which is better from this point of view than Group A. By analyzing the evolution of this volume of new bone in time, the most significant difference was after 21 days, therefore approximately after two thirds of the total time interval analyzed. After 30 days, the volumes of bone tend to move closer, as they begin to fill the available gap. The study demonstrates that OCT can assess quantitatively the positive impact of LLLT on bone regeneration.

Effect of the laser beam on implant site preparation: a preliminary pilot study.

The aim of this preliminary study is to histologically evaluate the effects of erbium-doped yttrium aluminum garnet (Er:YAG) laser on soft and hard tissues during implant bed preparation, in comparison with bur and cutter in order to observe the following aspects: (i) the shape of the cavity, (ii) the presence of debris, and (iii) structural modification of the cell architecture. Bone temperature changes during the preparation of the implant bed were also measured in order to evaluate thermal damage on soft and hard tissues. Er:YAG laser, Fotona X-Runner scanner and circular cutter of 5 mm diameter were compared using an in vitro model. Implant bed preparations were performed in bovine rib bone (hard tissue) and tongue muscle (soft tissue) tissues. Results of the study show that in all bur samples were present more debris and more blood cells than in laser samples, which, according to the rules of healing processes, can be a negative factor for the osseointegration process. Regarding the thermal effects on soft tissue, they were present when using MAX mode, but absent when using quantum square pulse (QSP) mode. A preliminary conclusion emphasizes the use of laser to prepare the implant site without debris formation. Nowadays, is not still present a laser device that can overtake the technical limitations of the laser scanner (i.e., deepness control and scanner movement during the preparation of the holes, etc.).

Scanning electron microscopy evaluation of the root canal morphology after Er:YAG laser irradiation.

The current limits of the endodontic disinfection strategies are not only a result of bacterial biofilm growth mode inside the root canals, they are equally due to the anatomical complexity of the root canal system, of its structure, of the dentin composition and of the factors associated with chemical disinfectants. One of the major problems is the fact that a great part of the endodontic anatomy remains uninstrumented after conventional treatment and even the accessible parts of the root canals are covered in smear layer, which results as a by-product of the instrumentation and acts as a barrier for irrigants, medication and even influencing the quality of the endodontic filling. Therefore, strategies in advanced disinfection in endodontics are developed and tested in order to meet these challenges. The present study aims to assess the possibility of improving the debridement of the root canals by using erbium-doped yttrium-aluminum-garnet (Er:YAG) laser radiation. We used extracted teeth, which were subjected to the conventional treatment protocol and then divided into three study groups: the negative control group and two other groups, which were exposed to laser radiation using two energy levels. Scanning electron microscopy (SEM) revealed the efficiency of the laser aided treatment versus the conventional methods of cleaning and disinfection of root canals.