This work reports on the effect of the amount (0, 10, and 30 wt %) and type of HA powder incorporated into an acrylic bone cement on the tensile properties, compression properties, and fracture toughness. The three different types of HA powders used were synthesized in the laboratory and coated with a silane agent prior to incorporation into the cement powder, and differed in particle size, water content, surface area, and crystallinity. It was found that the inclusion of any type of HA powder led to an increase in the tensile modulus (ET), but all the other mechanical properties of the cement decreased (relative to the values of the unfilled cement). The increase in ET is attributed to the good adhesion between the filler and the cement matrix, which is due to the silane coating agent. The decrease in the other mechanical properties may be a consequence of HA powder agglomeration and porosity. Hydroxyapatite morphology and crack-growth mechanisms were analyzed by scanning electronic microscopy (SEM).

Objectives. The purpose of this work was to determine the influence of residual alumina after sand blasting treatment in titanium dental implants. This paper studied the effect of alumina on physico-chemical surface properties, such as: surface wettability, surface energy. Osseointegration and bacteria adhesion were determined in order to determine the effect of the abrasive particles. Materials and Methods. Three surfaces were studied: (1) as-received, (2) rough surface with residual alumina from sand blasting on the surface and (3) with the same roughness but without residual alumina. Roughness was determined by white light interferometer microscopy. Surface wettability was evaluated with a contact angle video-based system and the surface free energy by means of Owens and Wendt equation. Scanning electron microscopy equipped with microanalysis was used to study the morphology and determine the chemical composition of the surfaces. Bacteria (Lactobacillus salivarius and Streptococcus sanguinis) were cultured in each surface. In total, 110 dental implants were placed into the bone of eight minipigs in order to compare the osseointegration. The percentage of bone-to-implant contact was determined after 4 and 6 weeks of implantation with histometric analysis. Results. The surfaces with residual alumina presented a lower surface free energy than clean surfaces. The in vivo studies demonstrated that the residual alumina accelerated bone tissue growth at different implantation times, in relation to clean dental implants. In addition, residual alumina showed a bactericidal effect by decreasing the quantity of bacteria adhering to the titanium. Conclusions. It is possible to verify the benefits that the alumina (percentages around 8% in weight) produces on the surface of titanium dental implants. Clinical relevance. Clinicians should be aware of the benefits of sand-blasted alumina due to the physico-chemical surface changes demonstrated in in vivo tests.

Articles on the prevalence of peri-implant diseases showed that 90% of peri-implant tissues had some form of inflammatory response and a prevalence of peri-implantitis from 28% to 51% according to various publications. Objective: To provide an overview of how risk factors can be related with peri-implantitis. Methods: A retrospective longitudinal study including 555 implants placed in 132 patients was evaluated based on the presence of peri-implantitis following the criteria of Renvert et al. 2018. Results: In total, 21 patients (15.9%) suffered peri-implantitis (PPG) and 111 patients (84.1%) did not suffer peri-implantitis (NPG). The results reveal that smokers have a high incidence of peri-implantitis (72.7%) compared to non-smokers (27.3%) (p < 0.0005). Another variable with significant results (p < 0.01) was periodontitis: 50% PPG and 23.9% NPG suffered advanced periodontitis. Systemic diseases such as arterial hypertension, diabetes mellitus, osteoporosis, and cardiovascular diseases do not show a statistically significant influence on the incidence of peri-implantitis. Patients who did not attend their maintenance therapy appointment had an incidence of peri-implantitis of 61.4%, compared to 27.3% in those who attend (p < 0.0001). From the results obtained, we can conclude that relevant factors affect peri-implantitis, such as tobacco habits, moderate and severe periodontitis, and attendance in maintenance therapy.

Aim: (PRIMARY) Assess the changes in bone level (6 and 12 months after implant placement) between the test (definitive abutment (DEF)) and control (healing abutment (HEA)) groups. (SECONDARY) Assess the changes in bone level (6 and 12 months after implant placement) between the 1 mm high abutment group and 2 mm abutment group. Evaluate changes in implant stability recorded with analysis of the resonance frequency (RFA) Osstell system, at 6 and 12 months after implant placement, between the control group (HEA) and test (DEF). For the DEF group, the abutment was placed at the time of the surgery and was never removed. For the HEA group, the abutment was removed three times during the manufacture of the crowns. The abutments used were 1 mm high (Subgroup A) and 2 mm high (Subgroup B). Materials and methods: A total of 147 patients were selected between 54.82 ± 11.92 years old. After implant placement, patients were randomly distributed in the DEF and HEA group. After the implant placement, a periapical radiograph was taken to assess the peri-implant bone level; the same procedure was carried out 6 and 12 months post-placement. To compare the qualitative variables between the groups (HEA/DEF), the Chi-square test was used; for quantitative (MANOVA). Results: After a year, the accumulated bone loss was 0.48 ± 0.71 mm for the HEA group and 0.36 ± 0.79 mm for the DEF group, without statistical significance. Differences were only found due to timing (time) between 0 and 6 months (=0.001) and 0 and 12 months (0.001), with no differences attributable to the study groups (DEF and HEA). The accumulated bone loss (1 year) was 0.45 ± 0.78 mm for the 1 mm abutment group and 0.41 ± 0.70 mm for the 2 mm abutment group (p = 0.02). No differences were observed in implant stability between groups. Conclusions: The “One Abutment—One Time” concept does not reduce peri-implant bone loss compared to the connection–disconnection technique. The height of the abutment does influence bone loss: the higher the abutment, the lower the bone loss.

Surface topography and physical-chemical properties usually play a key-role in both osseointegration improvement and bacterial colonization reduction over the surface of dental implants. The aim of this study is to compare the chemical and bacteriological behavior of two different acid passivation surface treatments on titanium c.p. grade 3 used for dental implant manufacturing. Surface roughness was evaluated using White Light Interferometry (WLI) in order to determine different roughness parameters such as average roughness (Sa), the spacing parameter (Sm) and the hybrid parameter of surface index area (SIA). Contact angle (CA) and surface free energy (SFE) were evaluated in order to establish the surface wettability of the different groups of samples. Titanium ion-release from the different samples was also been analyzed in Hank’s solution medium at 37 °C by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) at different immersion times. Bacterial viability adhesion assays were done using S. sanguinis (CECT 480, Spain) as a bacterial strain model of primary colonizer in oral biofilm formation. The bacteria attachment and morphology on Ti surfaces were determined using a live/dead staining method after 4 h of incubation and further analyzed by scanning electron microscope (SEM). Acid passivation surface treatments produced a statistically-significant (p < 0.05) roughness increase in all the evaluated parameters (Sa, Sm, SAI). The treatment with citric acid decreased the static contact angle (CA) and caused an increase in surface free energy (SFE) with a high polarization and oxidizing character. These physical-chemical surface characteristics obtained by means of citric acid passivation caused the bactericidal behavior as it has been proved in bacterial studies.