Eriberto Bressan

Influence of abutment material on the gingival color of implant-supported all-ceramic restorations: a prospective multicenter study

PURPOSE The aim of this clinical research on implant-supported restorations is to analyze, through spectrophotometric digital technology, the influence of the abutment material on the color of the peri-implant soft tissue. MATERIAL AND METHODS Twenty patients received an endosseous dental implant in the anterior maxilla. At the time of each definitive prosthesis delivery, an all-ceramic crown has been tried on gold, titanium and zirconia abutment. After the insertion of each single abutment, the peri-implant soft tissue color has been measured through a spectrophotometer. Also, the thickness of the facial peri-implant soft tissue was measured at the level of the implant neck through a caliper. A specific software has been utilized to identify a specific tissue area and to collect the data before the statistical analysis in Lab* color space. The normality of the quantitative variables was verified by means of the Shapiro-Wilk test. Simple linear correlation between quantitative variables was evaluated by using Pearsons coefficient. The results on the performance of the abutment materials with regard to the color measurements and the overall measurement ΔE were described by computing the least-square means. The significance of differences among types of abutment was verified by means of the Scheffe test for multiple comparisons. RESULTS For all the abutments used, the color of the peri-implant soft tissue appeared to be significantly different from the one of the contra-lateral tooth (ΔE>8.5). Significantly higher (P<0.05) difference were present with the use of titanium abutments (11 ± 0.4) when compared with the results of gold (8.9 ± 0.4) and zirconia (8.5 ± 0.4) abutments. No correlation has been demonstrated between soft tissue thickness and degree of color difference (P>0.25). CONCLUSIONS Within the limitation of the present study, the peri-implant soft tissue color appears to be different from the soft tissue color around natural teeth, no matter which type of restorative material is selected. When titanium abutment was selected, significantly higher differences were present than those obtained with gold or zirconia abutments. The thickness of the peri-implant soft tissue did not appear to be a crucial factor in the abutment impact on the soft tissue color.

Graphene based scaffolds effects on stem cells commitment

Graphene is a flat monolayer of carbon atoms, arranged in a two-dimensional hexagonal structure, with extraordinary electrical, thermal, and physical properties. Moreover, the molecular structure of graphene can be chemically modified with molecules of interest to promote the development of high-performance devices. Although carbon derivatives have been extensively employed in industry and electronics, their use in regenerative medicine is still in an early phase. Study prove that graphene is highly biocompatible, has low toxicity and a large dosage loading capacity. This review describes the ability of graphene and its related materials to induce stem cells differentiation into osteogenic, neuronal, and adipogenic lineages.

Silver Nanoparticles and Mitochondrial Interaction

Nanotechnology has gone through a period of rapid growth, thus leading to the constant increase in the application of engineered nanomaterials in daily life. Several different types of nanoparticles have been engineered to be employed in a wide array of applications due to their high surface to volume ratio that leads to unique physical and chemical properties. So far, silver nanoparticles (AgNps) have been used in many more different medical devices than any other nanomaterial, mainly due to their antimicrobial properties. Despite the promising advantages posed by using AgNps in medical applications, the possible health effects associated with the inevitable human exposure to AgNps have raised concerns as to their use since a clear understanding of their specific interaction with biological systems has not been attained yet. In light of such consideration, aim of the present work is the morphological analysis of the intracellular behavior of AgNps with a diameter of 10 nm, with a special attention to their interaction with mitochondria.

Incidence of inter‐proximal papilla between a tooth and an adjacent immediate implant placed into a fresh extraction socket: 1‐year prospective study

BACKGROUND Implant single-tooth replacement with a natural appearance is a challenging and demanding procedure. The aim of this prospective study was to identify the factors affecting the presence of an inter-proximal papilla between a tooth and an implant. METHODS Forty-six patients with a total of 46 teeth scheduled for tooth extraction and immediate implant placement into fresh sockets were included in the study. Immediate implants were positioned after teeth removal. After 4 months of healing, the implants were restored with single crown fixed prostheses. The following parameters were assessed: (1) presence/absence of the inter-proximal papilla, (2) gingival index, (3) inter-implant-tooth distance (ITD) and (4) distance from the base of the contact point to the inter-dental bone (CPB). A computerized analysis was performed to determine ITD and CPB values after converting perioapical radiographs to digitalized images. Statistical analyses were performed to determine the effect of ITD and CPB on the presence or absence of the inter-proximal papilla. RESULTS All the implants were restored, so that a 100% of implant survival rate was observed after 12 months of function. Mean values were recorded for ITD and CPB parameters, respectively. When ITD was 3-4 mm, and CPB was 3-5 mm, the inter-proximal papilla was significantly present (P<0.05). CONCLUSIONS The recommended inter-proximal space dimensions are 3-4 mm between an implant and the adjacent tooth, and 3-5 mm between the base of the CPB. The interaction between the surgical and prosthetic plans represents the key factor to optimize the edentulous site for predictable anterior single-implant esthetics.

Hard tissue formation adjacent to implants of various size and configuration immediately placed into extraction sockets: an experimental study in dogs

OBJECTIVES To evaluate the influence of implant size and configuration on osseointegration in implants immediately placed into extraction sockets. MATERIAL AND METHODS Implants were installed immediately into extraction sockets in the mandibles of six Labrador dogs. In the control sites, cylindrical transmucosal implants (3.3 mm diameter) were installed, while in the test sites, larger and conical (root formed, 5 mm diameter) implants were installed. After 4 months of healing, the resorptive patterns of the alveolar crest were evaluated histomorphometrically. RESULTS With one exception, all implants were integrated in mineralized bone, mainly composed of mature lamellar bone. The alveolar crest underwent resorption at the control as well as at the test implants. This resorption was more pronounced at the buccal aspects and significantly greater at the test (2.7+/-0.4 mm) than at the control implants (1.5+/-0.6 mm). However, the control implants were associated with residual defects that were deeper at the lingual than at the buccal aspects, while these defects were virtually absent at test implants. CONCLUSIONS The installment of root formed wide implants immediately into extraction sockets will not prevent the resorption of the alveolar crest. In contrast, this resorption is more marked both at the buccal and lingual aspects of root formed wide than at standard cylindrical implants.

Powder-based 3D printing for bone tissue engineering

Bone tissue engineered 3-D constructs customized to patient-specific needs are emerging as attractive biomimetic scaffolds to enhance bone cell and tissue growth and differentiation. The article outlines the features of the most common additive manufacturing technologies (3D printing, stereolithography, fused deposition modeling, and selective laser sintering) used to fabricate bone tissue engineering scaffolds. It concentrates, in particular, on the current state of knowledge concerning powder-based 3D printing, including a description of the properties of powders and binder solutions, the critical phases of scaffold manufacturing, and its applications in bone tissue engineering. Clinical aspects and future applications are also discussed.

Nanostructured Surfaces of Dental Implants

The structural and functional fusion of the surface of the dental implant with the surrounding bone (osseointegration) is crucial for the short and long term outcome of the device. In recent years, the enhancement of bone formation at the bone-implant interface has been achieved through the modulation of osteoblasts adhesion and spreading, induced by structural modifications of the implant surface, particularly at the nanoscale level. In this context, traditional chemical and physical processes find new applications to achieve the best dental implant technology. This review provides an overview of the most common manufacture techniques and the related cells-surface interactions and modulation. A Medline and a hand search were conducted to identify studies concerning nanostructuration of implant surface and their related biological interaction. In this paper, we stressed the importance of the modifications on dental implant surfaces at the nanometric level. Nowadays, there is still little evidence of the long-term benefits of nanofeatures, as the promising results achieved in vitro and in animals have still to be confirmed in humans. However, the increasing interest in nanotechnology is undoubted and more research is going to be published in the coming years.

Adipose Tissue Regeneration: A State of the Art

Adipose tissue pathologies and defects have always represented a reconstructive challenge for plastic surgeons. In more recent years, several allogenic and alloplastic materials have been developed and used as fillers for soft tissue defects. However, their clinical use has been limited by further documented complications, such as foreign-body reactions potentially affecting function, degradation over time, and the risk for immunogenicity. Tissue-engineering strategies are thus being investigated to develop methods for generating adipose tissue. This paper will discuss the current state of the art in adipose tissue engineering techniques, exploring the biomaterials used, stem cells application, culture strategies, and current regulatory framework that are in use are here described and discussed.

Donor Age-Related Biological Properties of Human Dental Pulp Stem Cells Change in Nanostructured Scaffolds

The aim of the present work is to study how biological properties, such as proliferation and commitment ability, of human adult dental pulp stem cells (DPSCs) relate to the age of the donor. Human dental pulps were extracted from molars of healthy adult subjects aged 16 to >66 years. DPSCs were isolated and cultured in the presence of osteogenic, neurogenic, or vasculogenic differentiation medium. Proliferation ability was evaluated by determining doubling time, and commitment ability was evaluated by gene expression and morphological analyses for tissue-specific markers. The results confirm a well-defined proliferative ability for each donor age group at an early in vitro passage (p2). DPSCs from younger donors (up to 35 years) maintain this ability in long-term cultures (p8). Stem cells of all age donor groups maintain their commitment ability during in vitro culture. In vivo tests on the critical size defect repair process confirmed that DPSCs of all donor ages are a potent tool for bone tissue regeneration when mixed with 3D nanostructured scaffolds.

In Vitro Concurrent Endothelial and Osteogenic Commitment of Adipose-Derived Stem Cells and Their Genomical Analyses Through Comparative Genomic Hybridization Array: Novel Strategies to Increase the Successful Engraftment of Tissue-Engineered Bone Grafts

In the field of tissue engineering, adult stem cells are increasingly recognized as an important tool for in vitro reconstructed tissue-engineered grafts. In the world of cell therapies, undoubtedly, mesenchymal stem cells from bone marrow or adipose tissue are the most promising progenitors for tissue engineering applications. In this setting, adipose-derived stem cells (ASCs) are generally similar to those derived from bone marrow and are most conveniently extracted from tissue removed by elective cosmetic liposuction procedures; they also show a great potential for endothelization. The aim of the present work was to investigate how the cocommitment into a vascular and bone phenotype of ASCs could be a useful tool for improving the in vitro and in vivo reconstruction of a vascularized bone graft. Human ASCs obtained from abdominoplasty procedures were loaded in a hydroxyapatite clinical-grade scaffold, codifferentiated, and tested for proliferation, cell distribution, and osteogenic and vasculogenic gene expression. The chromosomal stability of the cultures was investigated using the comparative genomic hybridization array for 3D cultures. ASC adhesion, distribution, proliferation, and gene expression not only demonstrated a full osteogenic and vasculogenic commitment in vitro and in vivo, but also showed that endothelization strongly improves their osteogenic commitment. In the end, genetic analyses confirmed that no genomical alteration in long-term in vitro culture of ASCs in 3D scaffolds occurs.