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Viene effettuata una rassegna degli innesti ossei

Background: Quantitative intraoperative evaluation of bone quality at implant placement site and postinsertion implantprimary stability assessment are two key parameters to perform implant-supported rehabilitation properly. A novelmicromotor has been recently introduced allowing to measure bone density at implant placement site and to recordimplant insertion-related parameters, such as the instantaneous, average and peak insertion torque values, and the insertiontorque/depth integral.Purpose: The aim of this study was to investigate in vivo if any correlation existed between initial bone-to-implant contact(BIC) and bone density and integral values recorded with the instrument.Materials and Methods: Twenty-five patients seeking for implant-supported rehabilitation of edentulous areas were consecutivelytreated. Before implant placement, bone density at the insertion site was measured. For each patient, anundersized 3.3 × 8-mm implant was placed, recording the insertion torque/depth integral values. After 15 minutes, theundersized implant was retrieved with a 0.5 mm-thick layer of bone surrounding it. Standard implants were consequentlyplaced. Retrieved implants were analyzed for initial BIC quantification after fixation, dehydration, acrylic resin embedment,sections cutting and grinding, and toluidine-blue and acid fuchsine staining. Correlation between initial BIC values, bonedensity at the insertion site, and the torque/depth integral values was investigated by linear regression analysis.Results: A significant linear correlation was found to exist between initial BIC and (a) bone density at the insertion site(R = 0.96, explained variance R2 = 0.92) and (b) torque/depth integral at placement (R = 0.81, explained varianceR2 = 0.66).Conclusions: The system provided quantitative, reliable data correlating significantly with immediate postinsertion initialBIC, and could therefore represent a valuable tool both for clinical research and for the oral implantologist in his/her dailyclinical practice.

The aim of the investigation was to evaluate the effects of surface mechanical treatments of all-Y-TZP restorations. In order to do that, surface roughness (Rs), fractal dimension (Df), fracture toughness (Ft), Vickers hardness (Hv), crack length (Cl), and opening (Co) were determined. MATERIALS AND METHODS: Y-TZP bar-shaped specimens (n = 30) were subdivided into three groups: as received by milling center (M), after coarse polishing (CP), and after fine polishing (FP). The specimens were examined under both confocal laser and electron scanning microscopes. One-way ANOVA and post hoc tests were used to analyze the data (α = 0.05). RESULTS: The FP group showed a significantly lesser amount of Rs (P

PURPOSE: The surface chemical and physical properties of materials used for implants have a major influence on blood clot organization. This study aims to evaluate the blood clot extension (bce) on zirconia and titanium. bce was measured in association to surface roughness (Ra) and static contact angle (θ).MATERIALS AND METHODS: Forty disk-shaped samples of sandblasted yttria tetragonal zirconia polycrystal (sb-YTZP), machined titanium (m-Ti), and sandblasted, high-temperature, acid-etched titanium (p-Ti) were used in the present study. About 0.2 mL of human blood, immediately dropped onto the specimen's surface and left in contact for 5 minutes at room temperature, was used to measure the bce. Specimens were observed under confocal scanning laser and scanning electron microscopes.RESULTS: The bce (mean × 10(7) ± standard deviation [SD] × 10(6) μm(2) ) was 2.97 ± 6.68 for m-Ti, 5.64 ± 6.83 for p-Ti, and 3.61 ± 7.67 for sb-YTZP. p-Ti samples showed a significantly higher bce. Ra (mean ± SD [μm]) was 0.56 ± 0.7 for m-Ti, 3.78 ± 0.8 for p-Ti, and 2.68 ± 0.6 for sb-YTZP. The difference was not significant between sb-YTZP and p-Ti. θ (mean ± SD) was 55.6 ± 5.6 for m-Ti, 48.7 ± 2.8 for sb-YTZP, and 38.0 ± 2.2 for p-Ti. The difference was not significant between m-Ti and sb-YTZP.CONCLUSIONS: The sb-YTZP demonstrated a significantly lesser amount of bce compared with p-Ti specimens, notwithstanding that any significant difference was present between Ra and θ.

Objectives: Aim of the paper was to make a revision on the bone microstructure adaptive mechanisms and function around dental implants and biomaterials. Materials and methods: The bone architecture was compared on the basis of ten years of histological evaluations made in both human and animal models. The following were treated in detail: immediate loading effect on bone collagen fiber orientation; osseointegration of dental implants in presence of biomaterials simultaneously placed with implants; bone microstructure differences between humans and animal models usually used in dental research. Results: Immediate loading procedure improves the peri-implant bone matrix organization. Likewise, the prevalent transverse collagen fibers orientation increases bone strength to compressive loads. Moreover, under an adequate mechanical stimulus the peri-implant bone became compact. A prevalent de novo bone formation around biomaterial's particles and a peri-implant "focal" osseintegration could be seen in the case of simultaneous placement of biomaterial and implants. Compared to humans, the bone microstructure and physiology of the most used animal models for in vivo studies appear to be significantly different. Conclusions: In implants with an adequate primary stability, immediate loading procedure improves the quality of osseointegration. Progressive loading procedure should be used after the second stage surgery in implants simultaneously inserted with a biomaterial. In in vivo animal research, both objectives of the studies and ethical considerations should be considered to choose the animal model

In this study we investigated the in vitro behaviour, morphostructure and extracellular matrix synthesis of human dental follicular stem cells (hDFSCs) isolated from human dental bud, which resulted to be positive for mesenchymal markers (CD29, CD90, CD146 and CD166) by FACS analysis. Cells were analysed by light and electronic microscopy to evaluate their biological response either at week 1, that is before differentiation, or at weeks 3-6, when they had been cultured in osteogenic medium onto a highly porous natural scaffold material (Bio-Oss). Microscopy analysis of primary culture cells showed they had a mesenchymal stem cell-like morphostructure, spindle shaped, similar to the culture of mesenchymal stem cells derived from adult bone marrow. Also, after osteogenic differentiation, these analyses indicate typical osteoblast morphostructure and reveale a tri-dimensional organization of the cells and deposition of extracellular matrix (ECM) in close contact with biomaterial. This approach would allow to personalize the scaffold for bone tissue engineering in order to accelerate the process of osteogenesis.

Objectives. The present in vitro study aimed at evaluating the fracture resistance of both implant-supported screw- and cement-retained porcelain fused to metal (PFM) single crowns. A scanning electron microscope (SEM) evaluation of the mode of failure of the spec- imens was also performed. Methods. Forty PFM premolar-shaped identical single crowns were realized. The restorations were divided into two groups: cement-retained (group 1) and screw-retained (group 2) pros- theses. Compressive loading tests and SEM fractographic analyses were performed. The data were statistically analysed by means of the Student’s t-test, with a confidence interval of 95%. Results. The mean fracture load value was 1657 (±725) N in group 1 and 1281 (±747) N in group 2; the statistical analysis pointed out no significant differences between the two groups (p = 0.115). The mean work at maximum load value was 0.775 (±0.619) J in group 1 and 0.605 (±0.526) J in group 2; the statistical analysis pointed out no significant differences between the two groups (p = 0.355). All the samples were affected by cohesive fractures of the porcelain. Screw-retained crowns showed microcracks at the level of the occlusal access to the screw and extensive fractures in the whole thickness of the ceramics. On the contrary, cement-retained restora- tions were affected by less wide paramarginal fractures of the porcelain. Significance. A stronger implant-prosthetic connection was noticed in cemented restora- tions group than in screw-retained single crowns. Even though negatively influenced by the presence of the occlusal access to the screw, the metal–ceramics bond can be considered predictable in both the implant-prosthetic connection systems analysed.