Polishing methods for composites restoration: the influence on human gingival fibroblasts behaviour.

BACKGROUND: Carious/Non-carious cervical lesions with gingival recessions may require both dental and periodontal reconstructive therapy, where flaps/grafts may be placed in contact with a dental filling material. Human Gingival Fibroblasts (HGF-1) response during the early phase of healing could vary according to the procedures employed to cure the dental composite. Moreover, oxygen diffusion into dental composite inhibits the polymerization reaction, creating an oxygen-inhibited layer (OIL) that presents residual unreacted monomers. The aim of this study was to assess the effect of different polishing techniques and OIL on HGF-1. METHODS: Composite discs polished with different techniques (diamond rubber, abrasive discs and tungsten carbide burr) were used. An additional not polished smooth group obtained with and without OIL was used as control. Samples were physically characterized through the analysis of their hydrophilicity and surface topography through contact angle measurement and SEM, respectively; afterwards the biologic response of HGF-1 when cultured on the different substrates was analyzed in terms of cytotoxicity and gene expression. RESULTS: The finishing systems caused alterations to the wettability, even if without a proportional relation towards the results of the proliferation essay, from which emerges a greater proliferation on surfaces polished with one-step diamond rubber and with abrasive discs as well as a direct effect of the glycerin layer, confirming that surface roughness can heavily influence the biological response of HGF-1. CONCLUSIONS: Surfaces wettability as well as cellular behavior seem to be affected by the selection of the finishing system used to lastly shape the restoration. Especially, the presence of OIL act as a negative factor in the regards of human gingival fibroblasts. The present study may provide the first clinical instruction regarding the best polishing system of composite material when the restoration is placed directly in contact with soft tissue cells. Understanding HGF-1 behavior can help identifying the polishing treatment for direct restoration of carious/non-carious cervical lesions associated with gingival recessions.

Combined photographic and ultrasonographic measurement of the ANB angle: a pilot study.

OBJECTIVE: This study was performed to evaluate the feasibility of noninvasive measurement of the ANB angle using photographic and ultrasonographic methods. METHODS: Twenty consecutive orthodontic patients were evaluated. The ANB angle and soft tissue thickness covering the N, A, and B cephalometric points were measured by lateral teleradiography; these measurements were made by two expert operators. The soft tissue thickness covering the N, A, and B cephalometric points was measured by ultrasonography; these measurements were also made by two expert operators. On a 1:1 photographic profile print on which the ultrasonographic points were marked, the ANB ultrasonographic angle was measured. The following comparisons were considered: averaged and single measurements of N, A, and B points by first versus second ultrasonographer; averaged and single ultrasonographic versus radiographic soft tissue thickness covering the N, A, B points; and averaged and single ultrasonographic versus radiographic measurements of ANB angle. RESULTS: High correlation and concordance of the averaged and single measurements, but no significant difference, was found between the two ultrasonographers. No statistically significant difference was found between the two methods for measuring averaged soft tissue thickness, but a 20% difference was found for the single measurements. High correlation and concordance between the ultrasonographic and radiographic measurements, but no significant difference, was found between the single and averaged ANB angle measurements. CONCLUSION: Ultrasonography seems to be a noninvasive and reliable technique for measurement of the ANB angle and may replace radiographic measurement in some cases.

Photogrammetric method to measure the discrepancy between clinical and software-designed positions of implants.

STATEMENT OF PROBLEM: The position of dental implants placed with software-guided systems should be highly accurate in order to ensure safety and a passive fit of the immediate prosthesis. PURPOSE: The purpose of this study was to measure the discrepancy between the clinical and software-planned position of dental implants by applying a photogrammetric method. MATERIAL AND METHODS: Two casts were obtained, 1 from the surgical template and 1 from the actual position of the implants on the alveolar ridge of a patient. Photogrammetry was then applied to precisely locate the position of each implant on the casts. Because this mathematical technique required the identification of image points and of the relative spatial coordinates, 4 marks were drilled on the implant screw. The position of the implants was then identified as the geometric center of the 4 marks, while the orientation of the implant axis was represented by a vector normal to the plane fitting the points. A series of 16 convergent images all around the object was made using a high-resolution digital camera. A mathematical method called "rototranslation" was used to superimpose the cast images for the comparison. RESULTS: The tests performed on the casts resulted in an average precision level of 4 µm for the locations and less than 1 degree for the axis of the implants. A series of empirical and numerical tests were performed to assess the performance of the procedure and of the measurement protocol. CONCLUSIONS: The photogrammetric method is reproducible and can be used to measure the discrepancy between the software-planned and the real position of dental implants. Considering that the average precision level required for an implant-based prosthesis is approximately 50 µm, the error associated with this method can be considered as negligible.

Awareness and attitude among general dentists and orthodontists toward obstructive sleep apnea in children.

Aim: This study aimed to investigate Italian dentists' knowledge of and attitudes toward obstructive sleep apnea (OSA) in children. Methods: An anonymous questionnaire was prepared using Google Forms and sent to dentists in Italy through private social platforms. The first part of the questionnaire contained basic demographic data questions, and the second part included items about pediatric OSA. Results: A total of 125 responses were collected within 1 month. The interviews revealed gaps in undergraduate and post-graduate training on OSA, and consequently, low self-evaluation of knowledge and self-confidence in managing young patients with OSA. Dentists showed unfavorable attitudes and poor knowledge of the general findings, risk factors, and consequences of pediatric OSA but demonstrated good knowledge of the beneficial effects of rapid maxillary expansion. Orthodontists showed a more favorable attitude and better recognition of the craniofacial features associated with OSA. In addition, a comparison was made between dentists who had graduated more than 5 years ago and new graduates, and differences were found in undergraduate education, which was better for new graduates, and a small number of questions were better answered by experienced dentists. Conclusion: This study showed a lack of knowledge about pediatric OSA and its management among Italian dentists, revealing the need to update the dentistry curriculum and organize educational interventions.

Thermal-induced hydrophilicity enhancement of titanium dental implant surfaces.

Titanium surface characteristics, including microtopography, chemical composition, and wettability, are essential features to achieve osseointegration of dental implants, but the choice of a particular surface topography is still a debated topic among clinicians. An increased level of implant surface hydrophilicity has been demonstrated to ameliorate osseointegration and shorten healing times. The aim of this work is to develop and test a suitable thermal-based method to enhance titanium surface wettability without modifying other characteristics of the implant surface. For this function, titanium discs with different surface topography have been thermally treated by testing different temperatures and excluding those that led to evident chromatic and morphological modifications. The selected surface gain in wettability after the treatment was assessed through contact angle measurement, chemistry modifications through x-ray photoelectron spectroscopy (XPS) analysis, and microtopography through scanning electron microscopy (SEM). Results showed a great enhancement in hydrophilicity on the tested surfaces without any other modification in terms of surface chemical composition and topography. A possible limitation of this method could be the persistent, although relatively slow, biological aging of the surfaces after the treatment. The present findings indicate that the described treatment could be a safe and effective method to enhance dental titanium hydrophilicity and thus its biological performance.

Osteoblasts preferentially adhere to peaks on micro-structured titanium.

The aim of the study was to investigate cell adhesion to micro-structured titanium. Osteoblastic MC3T3 cells were cultured on smooth (P) or sand-blasted/acid-etched (SLA) titanium discs and were observed at scanning electron microscope/focused ion beam (SEM/FIB). Myosin II and actin microfilaments were labelled for epifluorescence microscopy. FIB revealed that cell adhesion initiated centrally and expanded to the cell periphery and that cells attached on the substrate by bridging over the titanium irregularities and adhering mostly on surface peaks. Gaps were visible between concave areas and cytoplasm and areas around ridges represented preferred attachment points for cells. A different myosin distribution was observed between samples and myosin inhibition affected cell responses. Taken together our data indicate that cells attach on micro-rough titanium by bridging over its irregularities. This is likely mediated by myosin II, whose distribution is altered in cells on SLA discs.

Applicability of tooth derived stem cells in neural regeneration.

Within the nervous system, regeneration is limited, and this is due to the small amount of neural stem cells, the inhibitory origin of the stem cell niche and often to the development of a scar which constitutes a mechanical barrier for the regeneration. Regarding these aspects, many efforts have been done in the research of a cell component that combined with scaffolds and growth factors could be suitable for nervous regeneration in regenerative medicine approaches. Autologous mesenchymal stem cells represent nowadays the ideal candidate for this aim, thank to their multipotency and to their amount inside adult tissues. However, issues in their harvesting, through the use of invasive techniques, and problems involved in their ageing, require the research of new autologous sources. To this purpose, the recent discovery of a stem cells component in teeth, and which derive from neural crest cells, has came to the light the possibility of using dental stem cells in nervous system regeneration. In this work, in order to give guidelines on the use of dental stem cells for neural regeneration, we briefly introduce the concepts of regeneration and regenerative medicine, we then focus the attention on odontogenesis, which involves the formation and the presence of a stem component in different parts of teeth, and finally we describe some experimental approaches which are exploiting dental stem cells for neural studies.

Comparison of Environmental Scanning Electron Microscopy in Low Vacuum or wet mode for the investigation of cell biomaterial interactions.

AIM: The aim of the present study was to investigate the efficacy of environmental scanning electron microscopy (ESEM), in low vacuum mode (LV-ESEM) and in wet mode (wet-ESEM) in the assessment of cell-material interactions. METHODS: Mouse calvaria MC3T3 cells (ATCC) were seeded on commercially pure machined titanium discs of 10 mm diameter in Dulbecco modified MEM, 10% Fetal Bovine Serum, 1% Penicillin and Streptomycin and 1% Glutamine. Samples were then processed for microscope observation by rinse in Phosphate Buffer saline and fixation in 4.5% Glutaraldehyde. Samples were then rinsed in Sodium Cacodylate buffer and observed or dehydrated in alcohol prior to LV-ESEM observation. Fresh samples in 0.9% NaCl solution were observed in wet- ESEM. RESULTS: No significant loss of detail was observed when dehydrated or non dehydrated samples were analysed at LV-ESEM.The observation of fresh samples in wet-ESEM however proved difficult for the need to eliminate water which forms a layer covering the sample, thus hiding cell surface details. When reducing the vapor pressure in the chamber, the layer evaporated and NaCl immediately started to precipitate and cells collapsed, thus no further investigation was possible. CONCLUSIONS: The use of low vacuum-ESEM after cell fixation, but without dehydration or gold sputter coating proved a viable alternative to traditional high vacuum SEM observation.

Stanozolol promotes osteogenic gene expression and apposition of bone mineral in vitro

Abstract Stanozolol (ST) is a synthetic androgen with high anabolic potential. Although it is known that androgens play a positive role in bone metabolism, ST action on bone cells has not been sufficiently tested to support its clinical use for bone augmentation procedures. Objective: This study aimed to assess the effects of ST on osteogenic activity and gene expression in SaOS-2 cells. Material and Methods: SaOS-2 deposition of mineralizing matrix in response to increasing doses of ST (0-1000 nM) was evaluated through Alizarin Red S and Calcein Green staining techniques at 6, 12 and 24 days. Gene expression of runt-related transcription factor 2 (RUNX2), vitamin D receptor (VDR), osteopontin (SPP1) and osteonectin (ON) was analyzed by RT-PCR. Results: ST significantly influenced SaOS-2 osteogenic activity: stainings showed the presence of rounded calcified nodules, which increased both in number and in size over time and depending on ST dose. RT-PCR highlighted ST modulation of genes related to osteogenic differentiation. Conclusions: This study provided encouraging results, showing ST promoted the osteogenic commitment of SaOS-2 cells. Further studies are required to validate these data in primary osteoblasts and to investigate ST molecular pathway of action.

The effect of age, gender, and insertion site on marginal bone loss around endosseous implants: results from a 3-year trial with premium implant system.

OBJECTIVES: The goal of this study was to evaluate bone changes around endosseous implants in partially edentulous patients. MATERIALS AND METHODS: A total of 632 two-stage implants were placed in 252 patients. The implants had straight emergence profile, ZirTi surface, 3.3 to 5 mm diameter, and 8.5 to 13 mm length. Bone levels were assessed on orthopantomography immediately after surgery and after 36 months and marginal bone loss (MBL) was calculated from their difference. RESULTS: Cumulative survival rate was 98.73%. Overall MBL was 0.8 mm ± 0.03 (mean ± SEM). Higher MBL was observed around implants in the maxilla than in the mandible (P < 0.007). A relation between implant diameter and MBL (P < 0.0001) was observed in male and, more limitedly, female patients. Older patients had higher MBL in the maxilla, but not in the mandible (P < 0.0001). MBL progressively increased with age in male patients, but reached a peak already in the 50-60 years age group in the female subset (P < 0.001). CONCLUSIONS: The overall MBL is consistent with the available literature. Site difference and patient age and gender appear to significantly affect MBL, representing important factors to be considered during implant placement.

Fresh-frozen bone blocks for horizontal ridge augmentation in the upper maxilla: 6-month outcomes of a randomized controlled trial.

PURPOSE: This randomized controlled trial compared fresh-frozen versus autologous bone blocks for maxillary horizontal ridge augmentation in patients with Cawood and Howell class IV atrophies. MATERIALS AND METHODS: Twenty-four patients were allocated to the autologous and fresh-frozen groups in a 1:1 ratio. Patients underwent computed tomography scans 1 week and 6 months after surgery for graft volume and density analysis. Doxycycline was administered at day 120 and day 150 to label new bone formation. Biopsy for histologic and histomorphometric analyses was performed at reentry for implant insertion, 6 months after grafting. RESULTS: Fresh-frozen grafts had lower density than autologous bone. Autologous and fresh-frozen grafts lost, respectively, 25% and 52% of their initial volume (p = .0041). Histology revealed the presence of newly formed bone within both graft types, but clear signs of inflammation were present in fresh-frozen blocks. CONCLUSIONS: According to these 6-month results, autologous bone blocks are preferable to fresh-frozen bone grafts.

Correlation between density and resorption of fresh-frozen and autogenous bone grafts.

TRIAL DESIGN: This analysis compared the outcome of fresh-frozen versus autologous bone block grafts for horizontal ridge augmentation in patients with Cawood and Howell class IV atrophies. METHODS: Seventeen patients received autologous grafts and 21 patients received fresh-frozen bone grafts. Patients underwent CT scans 1 week and 6 months after surgery for graft volume and density analysis. RESULTS: Two autologous and 3 fresh-frozen grafts failed. Autologous and fresh-frozen grafts lost, respectively, 28% and 46% of their initial volume (P = 0.028). It is noteworthy that less dense fresh-frozen blocks lost more volume than denser grafts (61% versus 16%). CONCLUSIONS: According to these 6-month results, only denser fresh-frozen bone graft may be an acceptable alternative to autologous bone for horizontal ridge augmentation. Further studies are needed to investigate its behaviour at longer time points.