Giovanni Falisi

Mechanical influence of tissue culture plates and extracellular matrix on mesenchymal stem cell behavior: A topical review

Tissue engineering applications need a continuous development of new biomaterials able to generate an ideal cell–extracellular matrix interaction. The stem cell fate is regulated by several factors, such as growth factors or transcription factors. The most recent literature has reported several publications able to demonstrate that environmental factors also contribute to the regulation of stem cell behavior, leading to the opinion that the environment plays the major role in the cell differentiation. The interaction between mesenchymal stem cells (MSCs) and extracellular environment has been widely described, and it has a crucial role in regulating the cell phenotype. In our laboratory (Tecnologica Research Institute, Crotone, Italy), we have recently studied how several physical factors influence the distribution and the morphology of MSCs isolated from dental pulp, and how they are able to regulate stem cell differentiation. Mechanical and geometrical factors are only a small part of the environmental factors able to influence stem cell behavior, however, this influence should be properly known: in fact, this assumption must be clearly considered during those studies involving MSCs; furthermore, these interactions should be considered as an important bias that involves an high number of studies on the MSCs, since in worldwide laboratories the scientists mostly use tissue culture plates for their experiments.

Psychotropic drugs and bruxism

Introduction: Sleep and awake bruxism is defined as ‘a parafunctional activity including clenching, bracing, gnashing, and grinding of the teeth’. Some evidence suggests that bruxism may be caused by, or associated with, alterations in the CNS neurotransmission. Several classes of psychotropic drugs interfering with CNS activity may potentially contribute to bruxism. Thus, the purpose of this study was to examine relevant peer-reviewed papers to identify and describe the various classes of psychotropic substances that may cause, exacerbate or reduce bruxism as the result of their pharmacological action in CNS neurons. Areas covered: A literature search from 1980 to the present was performed using PubMed database. The term ‘bruxism’ was used in association with ‘psychotropic’, ‘dopamine (DA)’, ‘serotonin’, ‘histamine’, ‘antipsychotics’, ‘antidepressants’, ‘antihistaminergics’ and ‘stimulants’. Expert opinion: Studies on the effects of DA agonists (Levo-DOPA, psychostimulants) and antagonists (antipsychotics) identified a central role of DA in the pathogenesis of pharmacologically induced bruxism. Important information from studies on drugs acting on serotonin neurotransmission (antidepressants) was recognized. Other mechanisms involving different neurotransmitters are emerging. This is the case of antihistaminergic drugs which may induce bruxism as a consequence of their disinhibitory effect on the serotonergic system.

Epidemiological analysis on 2375 patients with TMJ disorders: basic statistical aspects

The aim of this work was to present data from a large sample of patients with Temporo-Mandibular Disorders (TMD) in order to clarify some aspects of the development of pathological conditions that affect large parts of the population. This preliminary work put in relation, through an epidemiological evaluation, anamnestic and clinical data collected from a sample of 2375 patients affected by TMD. Personal data were provided by questionnaire (age, sex, status, etc.), while clinical data were collected following a specific medical chart compiled in accordance with international criteria for TMD. An analysis of these data clearly showed that there were large quantities of variables involved in these disorders and which occur with a wide variety possible of clinical signs. This complexity, in accordance with the current knowledge that it is not able to clarify the etiology of these disorders, makes intricate both diagnostic then therapeutic aspects. You would find in front of a multi-factorial systemic disease that, interfering with the individual bioavailability, exposes him to the possibility of perceiving noxious stimuli which otherwise would not able to reach the pain threshold. To support this hypothesis is the data founded in this report that showed how many patients suffered, at the same time, by muscle and spinal pain associated to headache, pain that occur with high frequency from the same side. The presence of these painful conditions tends to underestimate the dysfunctional problems even if they occur with greater clinical prevalence. Further research should be carried out to clarify these controversial issues.

Innovative approach for the in vitro research on biomedical scaffolds designed and customized with CAD-CAM technology:

Introduction: Studies on biomaterials involve assays aimed to assess the interactions between the biomaterial and the cells seeded on its surface. However, the morphology of biomaterials is heterogeneous and it could be tricky to standardize the results among different biomaterials and the classic plastic plates. In this light, we decided to create, by means of computer-aided design (CAD) technology, a standardized sample model, with equal shape and sizes, able to fit into a classic shape of a 96-wells tissue culture plate (TCP). Methods: The design of this sample consists of a hole in the top in order to allow the injected cells to settle without them being able to slip from the sides of the sample to the bottom of the TCP wells. This CAD project is made using the software Pro-Engineer. The sample will totally fill the wells of the 96-well TCP. Dental pulp stem cells have been used to assess the ability of the different sample to support and promote the cell proliferation. Results: Twelve titanium, 12 gold–palladium, and 12 zirconium oxide customized samples were designed by means of the software cam powermill, by importing the .stl file created in Pro-Engineer software. The proliferation rate of the tested scaffolds showed to be similar to the control in the group with the customized shape. Conclusion: We think that our method can be useful to test different types of scaffolds when a greater accuracy of the measurements is desirable in order to verify the cell behavior of these scaffolds. Our innovative method can improve the standardization process in the evaluation of cell behavior on different biomaterials to open the way to more reliable tests on biomatrices functionalized with drugs or growth factors applied to the future regenerative medicine.

New Mandibular Advancement Device (BestMAD) in the Treatment of Obstructive Sleep Apnea: A Preliminary Study

Background: Oral appliances have emerged as an important alternative in treating patients with mild-moderate obstructive sleep apnea (OSA). They are effective, simple to use and well tolerated by the patient compared to other therapeutic solutions, such as continuous positive airway pressure (CPAP) or surgery of the upper airways. Aim: The aim of this preliminary study was to assess the effectiveness of a new mandibular advancement device, the BestMAD, in the treatment of OSA patients. Materials and methods: We selected 10 patients, 9 males and 1 female, with an average age of 51.5 years, affected by OSA, with a BMI (Body Mass Index) value ≤25 kg/m2. All patients used the BestMAD for at least 6 months. A control polysomnography was repeated after 6 months and a questionnaire was administered to assess the side effects eventually felt by the patient. Results: After treatment with BestMAD, a statistically significant improvement was found in AHI (p=0.0051), RDI (p=0.0051) and ESS (p=0.0049). With regard to adherence to the treatment, 8 patients claimed to have used the BestMAD for the entire duration of nocturnal rest, while the remaining 2 only for a few hours at night. Conclusions: BestMAD is a comfortable device which has proved effective in improving the polysomnographic parameters.

The effects of surgical preparation techniques and implant macro-geometry on primary stability: an in vitro study

Background The attainment of a good primary stability is a necessary condition to ensure the success of osseointegration in implantology. In type IV cancellous bone, however, it is possible that a reduced primary stability can lead to an increased rate of failure. The aim of this study was therefore to determine, with the help of the resonance frequency (Osstell mentor), which technique of implant site preparation (piezo surgery, conventional, under-preparation, bone compaction, osteodistraction) and macro-geometry is able to improve implant stability in type IV cancellous bone. Material and Methods 10 pig ribs were prepared with a surgical pre-drilled guide, calibrated for a correct implant positioning. On each rib, 5 implant sites (one for each technique) were prepared. Successively, 50 conical implants (Tekka Global D) were inserted and measured with the resonance frequency to evaluate the primary stability. Data collected were analyzed by analysis of variance (ANOVA) to test whether the Implant Stability Quotient (ISQ) values of the five techniques were significantly different. Results The results showed that no significant differences among the ISQ values of the five techniques used were found. Also, no significant differences in the macro-geometry of the two types of compared implants were observed. However, the macro-geometry of Tekka implants, characterized by a double condensing thread, seems to provide greater ISQ values than those of single thread implants when using the same technique. Conclusions In light of these preliminary data, it is conceivable that in cases of reduced stability, such as those occurring with a type IV bone, all means ameliorating the primary stability and accelerating the osseointegration can be utilized. Key words:Implant primary stability, resonance frequency analysis, implant site preparation.