Flavia Iaculli

Osteocyte density in the peri-implant bone of implants retrieved after different time periods (4 weeks to 27 years).

Bone tissue is characterized by a constant turnover in response to mechanical stimuli, and osteocytes play an essential role in bone mechanical adaptation. However, little to no information has been published regarding osteocyte density as a function of implantation time in vivo. The aim of this retrospective histological study was to evaluate the osteocyte density of the peri-implant bone in implants retrieved because of different reasons in a time period from 4 weeks to 27 years. A total of 18 samples were included in the present study. Specimens were divided into 3 groups depending on the loading history of the implants: loading between 4 weeks and 7 months (group 1); loading between 1 and 5 years (group 2); loading between 14 and 27 years (group 3). All the samples were histologically evaluated and osteocyte density was obtained using the ratio of the number of osteocytes to the bone-area (mm(2) ). The osteocyte density values significantly increased in the Group 2 (1-5 years) compared with Group 1 (4 weeks-7 months), and significantly decreased in the Group 3 (14-27 years) compared to Group 2. No significant differences were detected between Group 1 and Group 3. The decrease in osteocyte density observed in samples that were in vivo for long periods of time under loading is possibly because of the fact that once the bone structure is well aligned and biomechanically competent, a lower number of osteocytes are necessary to keep the tissue homeostasis under loading.

Relationship between the surface energy and the histologic results of different titanium surfaces.

AbstractThe aim of this study was to evaluate, through in vitro and in vivo studies, the existence of a relationship between surface energy, for wettability, and the clinical behavior of dental implants with different surfaces, one with a surface treated by sandblasting with titanium oxide microparticles followed by acid-etching treatment (experimental group) and another with a machined surface (control group). For the in vitro tests, a total of 30 titanium disks (15 disks for each group) were evaluated by scanning electron microscopy and dispersive energy spectroscopy and for surface roughness and wettability. For the in vivo tests, a total of 24 implants (12 implants for each group) were inserted in the tibiae of 6 rabbits and were removed after 30 and 60 days for histologic analysis. The results showed that the implants with the experimental surface presented a low wettability, and it also resulted in highly stimulated new bone formation in vivo, when compared with the control group dental implant. As for the bone formation, differences between the different surfaces seemed evident, both in quantity and in quality, as implants from the experimental group showed a higher new bone deposition than that from the control group. Thus, in vitro and in vivo tests demonstrated an excellent biologic response of the surfaces treated by sandblasting with microparticles of titanium oxide followed by acid etching.

Microleakage of bacteria in different implant-abutment assemblies: an in vitro study

Purpose The aim of the present in vitro study was to evaluate the leakage observed for 2 different microbial species at the level of the implant–abutment (I-A) interface, and the marginal fit and size of microgap at the I-A interface in 2 different implant connections. Methods Ten specimens of each group were tested. The inner parts of 5 implants per group were inoculated with 0.1 μL of a viable Enterococcus faecalis suspension and 5 implants per group with Aggregatibacter actinomycetemcomitans. All of the vials containing the control specimens were incubated at 37°C under aerobic condition for E. faecalis and 37°C in presence of 5% CO2 for A. actinomycetemcomitans. They were maintained for 14 days, and the possible penetration of bacterial suspension into the surrounding solution was determined by the observation of turbidity of the broth. The I-A interface was evaluated for size of microgap and measured under SEM. Five implants of each group were evaluated. The marginal fit between implant and abutment was measured at 8 random locations in each assembly, under different magnifications at the interface. Results No leakages through the I-A interface were demonstrated for either type of connection evaluated. The microgap values of all I-A interfaces ranged from 0.008 to 2.009 μm; the differences between the 2 systems were statistically significant. Conclusions The present study demonstrated that a good marginal fit of implant components seemed to be able to prevent bacterial leakage.

Dental pulp stem cells grown on dental implant titanium surfaces: An in vitro evaluation of differentiation and microRNAs expression.

The surface roughness of dental implants influences the proliferation and differentiation rate of adult mesenchymal stem cells (MSCs). The aim of the present study was to evaluate whether specifically treated titanium implant surfaces influenced human dental pulp stem cells (DPSCs) differentiation in an osteogenic pattern through modulation of microRNAs expression. The degree of differentiation was evaluated after 7, 14, and 21 days, through the expression of microRNAs characterizing the osteogenesis (miR-133 and miR-135), of Runx2 and Smad5 (key factor transcriptions associated with osteoblast differentiation) and Osteocalcin, marker for the bone formation process. DPSCs were cultured on sandblasted and acid-etched titanium disks, with (Test) or without the presence of ions (Control). Early differentiation of DPSCs cultured on titanium could be detected at all the evaluated time points, respect to cells grown alone. Moreover, the Test surfaces seemed to induce a more marked cells differentiation. The obtained results demonstrated that microRNAs played a pivotal role in the differentiation of MSCs and could be used as marker of osteogenic differentiation. Furthermore, the evaluated ionized sandblasted and acid-etched surface seemed to markedly enhance the development of osteoblast cells. A faster osseointegration could be achieved in the presence of specifically treated implant surfaces, promising encouraging clinical outcomes.

Sealing capability of implant-abutment junction under cyclic loading: a toluidine blue in vitro study

Purpose The aim of the present in vitro study was to evaluate the leakage observed in external hexagon (EH) and cone Morse (CM) tapered implant-abutment connections, using toluidine blue. Methods A total of 60 implants, 30 with a screw-retained EH abutment and 30 with a CM taper internal connection, were used. Toluidine blue was placed into the deepest portion of the internal compartment of the 2 different implant systems, and cyclic loading was applied for each group as follows: 10 samples underwent 1 × 106 loading cycles, 10 samples underwent 3 × 106 cyclic loading and the least 10 samples underwent 6 × 106 cyclic loading. Results No significant differences between the EH and CM groups were detected when the lowest loading cycles were applied (p = 0.2624), while differences were found when the samples were loaded with 3 x 106 and 6 x 106 cycles (p = 0.00124), with significantly lower toluidine leakage in CM group. Conclusions In conclusion, the results of the present in vitro study demonstrated that flow of the toluidine blue to the external portion of the implant-abutment assembly occurred in both types of implant-abutment connections, with very different percentages. Indeed, the CM taper internal connection seems to be more resistant to the leakage of dyes when compared with EH connections.

Degree of bacterial microleakage at the implant-abutment junction in Cone Morse tapered implants under loaded and unloaded conditions

Purpose Different results have been reported on the internal colonization of Cone Morse connections under in vitro dynamic loading. The aim of the present in vitro study was to evaluate the bacterial leakage in Cone Morse implant-abutment connections, both under loaded and unloaded conditions. Methods A total of 20 implants with a Cone Morse taper internal connection were used in this study. Ten were loaded under a special testing equipment (Test Group), while 10 were left unloaded (Control Group). The inner part of all implants was inoculated with 0.1 μl of a viable Enterococcus faecalis suspension. A force of 120 N was applied to the loaded implants, for a total of 500,000 cycles at 1 Hz. All the samples were checked daily, for a total of 14 days, and presence or absence of turbidity recorded. Results In the unloaded assemblies, bacterial contamination was found in 2 out of 10 implant-abutment junctions, on the 12th and 13th days. In the loaded implant-abutment connections, bacterial contamination was found in 2 out of 10 implant-abutment assemblies, on the 13th and on the 14th days. Conclusions The resistance of the Cone Morse implant-abutment junction reported in the literature and confirmed in the present study, where no differences in the percentages of microbial leakage were found in assemblies unloaded and in those subjected to a dynamic loading procedure, could help to explain the histological results in man of a lack of peri-crestal bone resorption in Cone Morse implants, placed below the level of the alveolar crest.

3D X-RAY MICROSCOPIC ANALYSYS ON A PROSTHETICALLY LOADED IMPLANT WITH PLATFORM-SWITCHING AND CONICAL CONNECTION: A CASE REPORT

The histological and histomorphometrical examination were the gold standard in the qualitative and quantitative analyses of the peri-implant tissue around the implant. In recent years, the field of microscopy has witnessed a considerable enhancement of the performance of microscopes that have very high resolution performance and allowing very sophisticated analysis even larger than traditional preparations. The possibility to have an affordable analyses of whole implant with the surrounding different tissues (soft and hard tissues) without the traditional pre-treatment necessary for the histological analysis may represent a goal to describe material properties and behaviors or simply to visualize structural details. The aim of the present study were to evaluate a 3D X-ray microscopic analysis of peri-implant tissue compared to a traditional histological and histomorphometrical analysis of the peri-implant tissues around an implant with a conical connection associated with platform-switching in order to assess the validity of the new analysis technique.

Histological and Histomorphometrical Analysis on a Loaded Implant With Platform-Switching and Conical Connection: A Case Report

&NA; The association of Morse taper implant‐abutment design with the use of a smaller abutment diameter (platform switching) may improve dental implant success rate and prevent peri‐implant bone loss. The aim of the present study was to histologically and histomorphometrically evaluate the behavior of peri‐implant tissues around an implant with a conical connection associated with platform switching. A platform‐switched Morse‐cone connection implant was inserted in the left posterior mandible of a 61‐year‐old patient. The implant was inserted at the level of the alveolar crest. After 11 months from placement and 6 months of loading, the implant was retrieved for psychological reasons and processed for histological evaluation. The retrieved implant was wholly surrounded by bone tissue, except for a small area in the apical portion. At higher magnification, in the coronal portion of the implant, it was possible to observe bone directly at the implant platform level. No resorption of the coronal bone was present, except for 0.2 mm on the vestibular aspect. Crestally, bone remodeling with areas of newly formed bone was detected; the bone‐implant contact was 73.9%. Apposition of bone was detected even upon the platform. Peri‐implant crestal bone preservation can be achieved with the combination of Morse taper conical internal implant‐abutment connection with the use of a smaller abutment diameter (platform‐switching).