Efecto de la co-inoculación de Burkholderia ubonensis y Rhizobium spp. en la nodulación de Pisum sativum

Las leguminosas tienen alto valor nutricional como fuente de proteínas y aminoácidos, además tienen la capacidad de restaurar o mantener la fertilidad de los suelos, siendo de vital importancia para ello, la asociación con su respectivo microbiota. Pisum sativum establece relaciones con bacterias consideradas promotoras del crecimiento vegetal, como es el caso de Burkholderia ubonensis, así también con proteobacterias del grupo de los rizobios para fijar el nitrógeno atmosférico. Con el objetivo de evaluar el efecto de la co-inoculación de B. ubonensis y Rhizobium spp. en la nodulación de P. sativum se diseñó un experimento con seis tratamientos distribuidos en bloques completamente randomizados. El tratamiento (T3) que mostró mayor número de nódulos radiculares de P. sativum fue cuando se inoculó solo Rhizobium spp., sin embargo, cuando se le co-inoculó con B. ubonensis (T6) disminuyó; un resultado distinto se obtuvo cuando se evalúo la masa seca de los nódulos, en ese caso la co-inoculación de Rhizobium spp. con B. ubonensis incrementó significativamente esta variable. Por lo tanto, se concluyó que la co-inoculación, de B. ubonensis y Rhizobium spp. no incrementa el número de nódulos de P. sativum, pero si incrementa la masa seca de los mismos

Evaluation of the primary stability in dental implants placed in low density bone with a new drilling technique, Osseodensification:an in vitro study

Primary stability is an important key determinant of implant osseointegration. We investigated approaches to improve primary implant stability using a new drilling technique termed osseodensification (OD), which was compared with the conventional under-drilling (UD) method utilized for low-density bones. We placed 55 conical internal connection implants in each group, in 30 low-density sections of pig tibia. The implants were placed using twist drill bits in both groups; groups Under Drilling (UD) and Osseodensification (OD) included bone sections subjected to conventional UD and OD drilling, respectively. Before placing the implants, we randomized the bone sections that were to receive these implants to avoid sample bias. We evaluated various primary stability parameters, such as implant insertion torque and resonance frequency analysis (RFA) measurements. The results showed that compared with implants placed using the UD technique, those placed using the OD technique were associated with significantly higher primary stability. The mean insertion torque of the implants was 8.87±6.17 Ncm in group 1 (UD) and 21.72±17.14 Ncm in group 2 (OD). The mean RFA was 65.16±7.45 ISQ in group 1 (UD) and 69.75±6.79 ISQ in group 2 (OD). The implant insertion torque and RFA values were significantly higher in OD group than in UD. Therefore, compared with UD, OD improves primary stability in low-density bones (based on torque and RFA measurements)

Influence of cortical bone and implant design in the primary stability of dental implants measured by two different devices of resonance frequency analysis : an in vitro study

This study aimed to evaluate the effect of the implant design and the presence of cortical bone in the primary stability, as well as analyze the differences between the stability measurements obtained by two different resonance frequency analysis (RFA) devices. A total of 80 Klockner implants of two different models [40 Essential Cone implants (group A) and 40 Vega implants (group B)] were used. The implants were placed in two polyurethane blocks that simulated the mechanical properties of the maxillary bone. One block featured a layer of cortical bone that was absent from the other block. The primary stability of all implants was measured by insertion torque and RFA using two different devices: Penguin RFA and Osstell IDX. Primary stability was superior in the cortical bone in both torque and RFA. In the block containing cortical bone, group A implants obtained a greater insertion torque than did group B. The insertion torque was lesser in the bone lacking cortex. Regarding the ISQ of the implants, group A presented higher values in the block with cortical bone, but the values were lower in the block without cortical bone. There were no significant differences between the values obtained from the Osstell IDX and Penguin RFA. The presence of cortical bone positively influences the primary stability of dental implants. The design of the implant also has a statistically significant influence on implant primary stability, although the impact depends on whether there is coronal cerclage or not. There were no statistically significant differences in the implant stability measurements obtained by two different devices

Biomechanical evaluation of oversized drilling technique on primary implant stability measured by insertion torque and resonance frequency analysis

Background: This study evaluated the influence of implant site preparation depth on primary stability measured by insertion torque and resonance frequency analysis (RFA). Material and Methods: Thirty-two implant sites were prepared in eight veal rib blocks. Sixteen sites were prepared using the conventional drilling sequence recommended by the manufacturer to a working depth of 10mm. The remaining 16 sites were prepared using an oversize drilling technique (overpreparation) to a working depth of 12mm. Bone density was determined using cone beam computerized tomography (CBCT). The implants were placed and primary stability was measured by two methods: insertion torque (Ncm), and RFA (implant stability quotient [ISQ]). Results: The highest torque values were achieved by the conventional drilling technique (10mm). The ANOVA test confirmed that there was a significant correlation between torque and drilling depth (p<0.05). However, no statistically significant differences were obtained between ISQ values at 10 or 12 mm drilling depths (p>0.05) at either measurement direction (cortical and medullar). No statistical relation between torque and ISQ values was identified, or between bone density and primary stability (p>0.05). Conclusions: Vertical overpreparation of the implant bed will obtain lower insertion torque values, but does not produce statistically significant differences in ISQ values

Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis

The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conventional (Ti-6Al-4V), and hyperelastic (Ti-Nb-Zr). A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP) transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone

Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis

The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conventional (Ti-6Al-4V), and hyperelastic (Ti-Nb-Zr). A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP) transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone

Monolithic and Minimally Veneered Zirconia Complications as Implant-Supported Restorative Material: A Retrospective Clinical Study up to 5 Years

Objective. Long-term clinical data on the success and complication rates of monolithic or minimally veneered zirconia implant-supported restorations are lacking. Hence, the purpose of this retrospective clinical study was to analyze the complications of monolithic or partially veneered zirconia implant-supported restorations up to 5 years follow-up. Material and Methods. Single crowns, bridges, and full-arch rehabilitations were included. The selection process was achieved by reviewing data from the prosthetic laboratory and excluding cases in which zirconium and full-ceramic coating restorations were used. A total of 154 restorations were included (82 monolithic and 72 with buccal ceramic stratification). All the complications encountered, and the solutions applied, were explained. Results. A total of 93 restorative units had a follow-up of between 24 and 60 months, and 61 restoration units had a follow-up of between 12 and 24 months. A total of 7 complications were encountered (14.58% of cases; 95.45% per prosthetic unit). The technical complication rate was 2.08% (one case of minor chipping in one prosthetic unit); regarding the mechanical complications, four decementations (8.33% of the cases) and two screw loosening (4.17% of the cases) were encountered. Conclusions. Considering the limitations of this study, it can be concluded that monolithic or partially veneered zirconia implant-supported restorations have a good clinical behavior during a follow-up period of up to 5 years