About stem cell research in dentistry: many doubts and too many pitfalls still affect the regenerative dentistry

Histological and immunohistochemical characteristic of the gingival stroma in the portion of the third molars in children of various age

OBJECTIVE

Aim: To evaluate the state of the gingival stromal elements in the portion of the third molars requiring extraction of these teeth due to orthodontic indications considering the stage of tooth germ formation.

PATIENTS AND METHODS

Materials and Methods: The surgery to extract third molars due to orthodontic indications was performed on 95 children aged 11 to 18 years. The three groups of observation were isolated according to clinical-radiological signs: І (n=30) - children aged 11-13 years; ІІ (n=35) - children aged 13-16 years, and ІІІ (n=30) - children aged 16-18 years. During surgery, the samples of gums were taken from the adjacent areas for examination. The samples were fixed, dehydrated, paraffinized for further histological processing. Immunohistochemical methods were used according to the protocols supplied by a producer. In particular, by means of immunohistochemical method, Ki-67, CD-34 antigens and vimentin with primary antibodies against them were determined. The primary antibodies were visualized by the polymeric visualization system with diaminobenzidine giving a brown color to the places of location of the antigens examined. The data obtained were statistically processed.

RESULTS

Results: The results of the study showed that specific gravity of the vascular bed in the gingival papillary layer of children was the most variable. It ranges from (12,7±0,09) % at the stage of "D" root formation to (54,8±0,17) % at the "H" stage. Lower concentrations of CD-34 antigens and vimentin are found in the endotheliocytes of children aged 13-16 and 16-18 years, compared to the children aged 11-13 years (p<0,05). No changes were found in the specific volume of the blood vessels, CD-34 antigens and vimentin in the reticular gingival layer of children from the groups of observation.

CONCLUSION

Conclusions: Therefore, the conducted histological and immunohistochemical study of the connective gingival tissues in the portion of the third molars in children enables to draw a conclusion that in the process of formation of the root of this tooth a number of changes occur in the gingival stroma. They include an increase of the blood flow volume in the papillary gingival layer on the background of a decreased concentration of CD-34 genes and vimentin, a longer stage of development of the third molar root. The specific volume of the islets of neoangiogenesis of the papillary gingival layer is the largest in children aged 13-16 years.

Comparative in vitro study on biomechanical behavior of zirconia and polyetheretherketone biomaterials exposed to experimental loading conditions in a prototypal simulator

Zirconia and polyetheretherketone (PEEK) are two biomaterials widely investigated as substitute for metals in oral prosthetic rehabilitation. To achieve a proper biomechanical behavior, the prosthetic biomaterials must ensure a good resistance to loads, as this is a crucial characteristic enabling their use in dental applications. The aim of this study was to investigate differences in the fracture resistance of different biomaterials in an experimental environment: fixed partial dentures (FPDs) screwed in a prototype of biomimetic mandible. 10 Samples of FPDs were allocated in 2 groups (A and B): Group A (n=5) involved FPDs in zirconia-ceramic, and Group B (n=5) involved FPDs in PEEK-composite. The samples were loaded by means of a three-point bending mechanical test, and the load to fracture has been evaluated generating a point-by-point graphics (speed/load and time/deformation). The samples were further analyzed by micro-computed tomography (micro-CT) and described under experimental loading conditions. Zirconia-ceramic FDPs were the samples reporting the worst results, showing a lower value of vertical displacement with respect to PEEK-based samples. The micro-CT results have further confirmed the preliminary results previously described. This in vitro study aims to give analytic data on the reliability of PEEK as a reliable and strong biomaterial for prosthetic treatments.

Antibiotic Abuse and Antimicrobial Resistance in Hospital Environment: A Retrospective Observational Comparative Study

Background and Objectives: Antimicrobial resistance represents a serious problem, and it may be life-threatening in the case of severe hospital-acquired infections (HAI). Antibiotic abuse and multidrug resistance (MDR) have significantly increased this burden in the last decades. The aim of this study was to investigate the distribution and susceptibility rates of five selected bacterial species (E. coli, K. pneumoniae, P. aeruginosa, S. aureus and E. faecium) in two healthcare settings located in the Apulia region (Italy). Materials and Methods: Setting n.1 was a university hospital and setting n.2 was a research institute working on oncological patients. All the enrolled patients were diagnosed for bacterial HAI. The observation period was between August and September 2021. Clinical samples were obtained from several biological sources, in different hospital wards. Bacterial identification and susceptibility were tested by using the software VITEC 2 Single system. Results: In this study, a higher incidence of multi-drug-resistant K. pneumoniae was reported (42,2% in setting n.1 and 50% in setting n.2), with respect to the Italian 2019 statistics report (30.3%). All the isolates of E. faecium and S. aureus were susceptible to linezolid. All the bacterial isolates of P. aeruginosa and most of K. pneumoniae were susceptible to ceftazidime–avibactam. Amikacin and nitrofurantoin represented a good option for treating E. coli infections. Multidrug-resistant (MDR) P. aeruginosa, methicillin-resistant S. aureus (MRSA) and vancomycin-resistantE. faecium (VRE) had a lower incidence in the clinical setting, with respect to E. coli and K. pneumoniae. Conclusions: The data obtained in this study can support clinicians towards a rational and safe use of antibiotics for treating the infections caused by these resistant strains, to enhance the overall efficacy of the current antibiotic protocols used in the main healthcare environments.

The Dental-BIOfilm Detection TECHnique (D-BioTECH): A Proof of Concept of a Patient-Based Oral Hygiene

To date, no strong long-term data have been reported about new innovative clinical protocols to manage oral hygiene. An improper management of oral hygiene may lead to an increase in dental implant failure, and to an increase in infective complications in prosthetic rehabilitation. Personalized techniques are strongly required in dentistry and dental hygiene. A customized and personalized approach to oral hygiene is crucial in ensuring not only effective treatment, but also a careful analysis of the general health status of the patient involved in the therapeutic process. D-BioTECH is an acronym for Dental BIOfilm Detection Technique: it is based on a tailored approach to patients, ensuring that the operator actively interacts with the patient and their specific needs, especially during the domiciliary therapy. D-BioTECH is an approach to preventive care: in D-BioTECH, both dental hygienists and dentists play a central role. The use of a personalized approach to oral hygiene is the first step towards increasing implant and prosthesis survival rate; moreover, personalized medicine is strategic for managing and preventing the biological complications associated with several dental risk factors.

Cells: Are They (Still) Essential for Dental Regeneration?

Tissue regeneration in dentistry has demonstrated impressive progress over during the last decades compared to other medical sciences [...].

Strategic Tools in Regenerative and Translational Dentistry

Human oral-derived stem cells can be easily obtained from several oral tissues, such as dental pulp, periodontal ligament, from gingiva, or periapical cysts. Due to their differentiation potential, oral-derived mesenchymal stem cells are promising for tissue engineering and regenerative medicine. The regenerative ability showed by some oral tissues strongly depends on their sleeping adult stem cell populations that are able to repair small defects and to manage local inflammation. To date, researchers are working on effective and efficient methods to ensure safe and predictable protocols to translate stem cell research into human models. In the last decades, the challenge has been to finally use oral-derived stem cells together with biomaterials or scaffold-free techniques, to obtain strategic tools for regenerative and translational dentistry. This paper aims to give a clear point of view on state of the art developments, with some exciting insights into future strategies.

Osteogenic potential of mesenchymal stem cells from rat mandible to regenerate critical sized calvarial defect

Although bone marrow–derived mesenchymal stem cells (MSCs) have been extensively explored in bone tissue engineering, only few studies using mesenchymal stem cells from mandible (M-MSCs) have been reported. However, mesenchymal stem cells from mandible have the potential to be as effective as femur-derived mesenchymal stem cells (F-MSCs) in regenerating bone, especially in the orofacial regions, which share embryonic origin, proximity, and accessibility. M-MSCs were isolated and characterized using mesenchymal stem cell–specific markers, colony forming assay, and multi-potential differentiation. In vitro osteogenic potential, including proliferation, osteogenic gene expression, alkaline phosphatase activity, and mineralization, was examined and compared. Furthermore, in vivo bone formations of F-MSCs and M-MSCs in rat critical sized defect were evaluated using microCT and histology. M-MSCs from rat could be successfully isolated and expanded while preserving their MSC’s characteristics. M-MSCs demonstrated a comparable proliferation and mineralization potentials and in vivo bone formation as F-MSCs. M-MSCs is a promising cell source candidate for craniofacial bone tissue engineering.