Livia Nastri

Human gingival fibroblast functions are stimulated by oxidized nano-structured titanium surfaces

OBJECTIVES The aim of this study was to analyze the features of an oxidized titanium implant surface and to evaluate its effects on the response of human gingival fibroblasts. METHODS 10mm×10mm×1mm turned (control) and oxidized (test) titanium samples (P.H.I. s.r.l., Italy) were examined by scanning electron microscopy and atomic force microscopy and characterized by height, spatial and hybrid roughness parameters. Primary cultures of human gingival fibroblasts were seeded on titanium samples, and cell morphology, adhesion, proliferation and extracellular matrix deposition, in terms of type I collagen synthesis, were evaluated. RESULTS Control and test surfaces appeared considerably different at the microscopic analyses: turned samples were grooved, whereas oxidized surfaces showed a more complex micro- and nano-scaled texture, as evidenced by roughness parameters. Cell adhesion and proliferation rate, as well as collagen synthesis, were greater on oxidized vs turned surfaces. CONCLUSIONS Although both control and test samples were in the range of average roughness proper of smooth surfaces, they exhibited significantly different topographic properties in terms of height and, mostly, hybrid parameters. Furthermore, oxidized surfaces enhanced human gingival fibroblast adhesion, proliferation and extracellular matrix deposition, and this could be due to the different structure at micro- and nano-scale levels. CLINICAL SIGNIFICANCE Oxidized nanostructured titanium surfaces could have a significant clinical utilization in virtue of their affinity for soft tissue attachment at the implant neck and/or at the transmucosal portion of the prosthetic abutment.

Bacterial inactivation/sterilization by argon plasma treatment on contaminated titanium implant surfaces: In vitro study.

Background Surface treatment by argon plasma is widely used as the last step of the manufacturing process of titanium implant fixtures before their sterilization by gamma rays. The possibility of using such a technology in the daily clinical practice is particularly fascinating. The aim of the present study was to assess the effects of the argon plasma treatment on different titanium implant surfaces previously exposed In vitro to bacterial contamination. Material and Methods Sterile c.p. titanium implant discs with turned (T, Sa: 0.8 µm ), sandblasted/acid-etched (SAE, Sa: 1.3 µm) and titanium plasma sprayed (TPS, Sa: 3.0µm) surface were used in this study. A strain of Aggregatibacter actinomycetemcomitans ATCC3718 was grown at 37°C under anaerobic conditions for 24 h and then transferred on six discs for each of the three surface types. After 24 hours, a half of the contaminated discs (control group) were directly used to evaluate the colony forming units (CFUs). The other half of the contaminated discs (test group) were treated in an argon plasma chamber for 12 minutes at room temperature prior to be analyzed for CFU counting. All assays were performed using triplicate samples of each material in 3 different experiments. Results When the CFU counting was carried out on control discs, a total of 1.50x106±1.4x105, 1.55x106±7.07x104 and 3.15x106±2.12x105 CFU was respectively assessed for T, SAE and TPS discs, without statistically significant differences among the three surfaces. On the contrary, any trace of bacterial contamination was assessed for titanium discs treated in the argon plasma chamber prior to be analyzed, irrespectively to the implant surface tested. Conclusions Within the limit of this study, reported data suggested that the argon plasma technology could be efficiently used to decontaminate/sterilize previously infected titanium implant surfaces. Key words:Argon plasma, titanium implant surface, Aggregatibacter actinomycetemcomitans.

Poly-D-L-lactic acid membranes for bone regeneration

Purpose:To histologically and histomorphometrically evaluate the biocompatibility and the biological properties of perforated and nonperforated poly-D-L-lactic acid (PDLLA) resorbable membranes, using a model of calvarial monocortical bone defects in domestic pigs. Methods:A total of 6 10 × 10 × 10 mm circular calvarial bone defects were prepared in each of the 3 adult female large white domestic pigs and assigned to the following experimental groups: negative control, nonperforated membrane only, perforated membrane only, bone only, bone + nonperforated membrane, and bone + perforated membrane. The PDLLA membranes were fixed by PDLLA pins by means of an ultrasonic device. After 40 days, bone blocks containing the defects were harvested and histologically processed. Results:A close contact between the PDLLA devices and the surrounding bone was found, and no trace of inflammatory tissue or signs of infection were detected. Bone regeneration occurred from the preexisting bone with a centripetal pattern. Incomplete bone filling was found in empty defects, whereas all sites filled with bone showed a complete bone formation, irrespectively of the presence and the type of membrane used. Conclusion:PDLLA membranes and pins showed to be highly biocompatible toward bone tissue and to do not interfere with the bone healing process of monocortical calvaria defects in domestic pigs. No adjunctive effect of PDLLA membranes, irrespectively of their perforated/nonperforated structure, could be evidenced in terms of bone regeneration under the present experimental conditions. Further studies are needed to investigate the regenerative potential of such devices in other clinically relevant models.

Vitamin D reduces the inflammatory response by Porphyromonas gingivalis infection by modulating human β-defensin-3 in human gingival epithelium and periodontal ligament cells

Abstract Periodontitis is a multifactorial polymicrobial infection characterized by a destructive inflammatory process. Porphyromonas gingivalis, a Gram‐negative black‐pigmented anaerobe, is a major pathogen in the initiation and progression of periodontitis; it produces several virulence factors that stimulate human gingival epithelium (HGE) cells and human periodontal ligament (HPL) cells to produce various inflammatory mediators. A variety of substances, such as vitamin D, have growth‐inhibitory effects on some bacterial pathogens and have shown chemo‐preventive and anti‐inflammatory activity. We used a model with HGE and HPL cells infected with P. gingivalis to determine the influence of vitamin D on P. gingivalis growth and adhesion and the immunomodulatory effect on TNF‐&agr;, IL‐8, IL‐12 and human‐&bgr;‐defensin 3 production. Our results demonstrated, firstly, the lack of any cytotoxic effect on the HGE and HPL cells when treated with vitamin D; in addition, vitamin D inhibited P. gingivalis adhesion and infectivity in HGE and HPL cells. Our study then showed that vitamin D reduced TNF‐&agr;, IL‐8, IL‐12 production in P. gingivalis‐infected HGE and HPL cells. In contrast, a significant upregulation of the human‐&bgr;‐defensin 3 expression in HGE and HPL cells induced by P. gingivalis was demonstrated. Our results indicate that vitamin D specifically enhances the production of the human‐&bgr;‐defensin 3 antimicrobial peptide and exerts an inhibitory effect on the pro‐inflammatory cytokines, thus suggesting that vitamin D may offer possible therapeutic applications for periodontitis. HighlightsVitamin D inhibits Porphyromonas gingivalis infectivity in human gingival epithelium and periodontal ligament cellsVitamin D reduces TNF‐&agr;, IL‐8, IL‐12 production in infected cells with Porphyromonas gingivalisVitamin D enhances the production of the human‐&bgr;‐defensin 3 in infected cells with Porphyromonas gingivalis

The Role of Autologous Platelet Concentrates in Alveolar Socket Preservation: A Systematic Review

Prevention of alveolar bone resorption after tooth extraction may be useful for implant rehabilitation of the edentulous site minimizing the future need for bone augmentation procedures. A number of studies have investigated the efficacy of autologous platelet concentrates for the preservation of the alveolar bone volume after tooth extraction. Although encouraging results have been published, the available data are still controversial. The aim of the present systematic review was to assess the effect of platelet concentrates on alveolar socket preservation after tooth extraction. A literature search was carried out up to September 2017 for prospective controlled trials in which a test group using exclusively a platelet concentrate was compared with a control group in which extraction sockets were left to heal spontaneously. Seven controlled clinical trials published between 2010 and 2016 were included. A total of 320 extractions (170 tests and 150 controls) in 190 patients was considered. A great heterogeneity was found in terms of study design, methodological aspects, and outcome evaluation. For this reason, a quantitative analysis followed by meta-analysis was not possible, and only a descriptive analysis on the role of platelet concentrates in alveolar socket preservation was carried out. There is growing evidence that platelet concentrates may be advantageously used in postextraction sites, mainly to improve soft tissue healing and to reduce postoperative symptoms. Data about their potential in preserving the alveolar bone volume are still scarce and controversial, although recently encouraging results have been presented using more reliable and accurate evaluation technologies, such as the computed tomography. Further, well-designed and methodologically standardized investigations are strongly demanded to reach a higher level of evidence on this topic.

The Use of Poly-d,l-lactic Acid (PDLLA) Devices for Bone Augmentation Techniques: A Systematic Review

Poly-d,l-lactic acid (PDLLA) has been proposed in dentistry for regenerative procedures in the form of membranes, screws, and pins. The aim of this review was to evaluate the efficacy of bone augmentation techniques using PDLLA devices. A literature search was carried out by two independent and calibrated reviewers. All interventional and observational studies assessing the efficacy of bone augmentation techniques using PDLLA devices were included. Six studies were included. The relevant variability of design and methods impeded any qualitative or quantitative comparison. Ease of handling, absence of a re-entry phase, moldability of foils, and good soft-tissue response were appreciated characteristics of PDLLA devices. Some drawbacks such as the risk of membrane exposition, a prolonged adsorbability, and a tendency to a fibrous encapsulation of the PDLLA devices have been described, although the clinical significance of these findings is unclear. Clinical data about PDLLA devices for bone regeneration are very scarce and heterogenous. Well-designed randomized controlled trials comparing the use of PDLLA foils and pins with conventional membranes for bone regeneration are strongly encouraged in order to understand the real clinical benefits/drawbacks of this technique.

Alternative Treatment Approaches in Chronic Periodontitis: Laser Applications

Periodontal disease is initiated by pathogenic plaque biofilm and characterized by bacteriainduced inflammatory destruction of tooth-supporting structures and alveolar bone (Lui & Corbet, 2011). With a constant bacterial challenge, the periodontal tissues are continuously exposed to specific bacterial components that have the ability to alter many local functions. The role of the inflammatory process is to protect the host and limit the pathogenic effect of biofilm, thus determining some tissue destruction as a collateral effect of the defence. The extent and severity of damage vary among individuals and over time (Offenbacher, 1996;Kinane et al., 2005; Karlsson et al., 2008), mainly influenced by individual’s immune and inflammatory responses to microbial challenge. In some patients gingivitis progresses to periodontitis, with a slower or faster progression, that is characterized by the destruction of the supporting structures of the teeth, including periodontal ligament and bone, and cementum alterations, that may in turn ultimately cause tooth loss (Kinane, 2001). Unfortunately, little and still uncertain is the possibility to interfere with individual response, to redirect inflammatory and immune defences or, as it is commonly defined, to perform a “host modulation”. The rationale behind this approach is to aid the host in its fight against infectious agents by supplementing the natural defence mechanism or to modify its responses by changing the course of inflammatory systems. Therefore, pharmaceutical inhibition of host response with an anti-inflammatory mechanism may prove to be an effective strategy for treating periodontal diseases. Current research has focused on the use of subantimicrobial dose of doxycycline (SDD) as a treatment modality, and SDD is the only systemically used host modulatory drug approved by the United States Food and Drug Administration. (Deo et al., 2010) (Figure 1).