Study of two bovine bone blocks (sintered and non-sintered) used for bone grafts: physico-chemical characterization and in vitro bioactivity and cellular analysis

High-temperature compression and electron backscatter diffraction (EBSD) techniques were used in a systematic investigation of the dynamic recrystallization (DRX) behavior and texture evolution of the Inconel625 alloy. The true stress–true strain curves and the constitutive equation of Inconel625 were obtained at temperatures ranging from 900 to 1200 °C and strain rates of 10, 1, 0.1, and 0.01 s−1. The adiabatic heating effect was observed during the hot compression process. At a high strain rate, as the temperature increased, the grains initially refined and then grew, and the proportion of high-angle grain boundaries increased. The volume fraction of the dynamic recrystallization increased. Most of the grains were randomly distributed and the proportion of recrystallized texture components first increased and then decreased. Complete dynamic recrystallization occurred at 1100 °C, where the recrystallized volume fraction and the random distribution ratios of grains reached a maximum. This study indicated that the dynamic recrystallization mechanism of the Inconel625 alloy at a high strain rate included continuous dynamic recrystallization with subgrain merging and rotation, and discontinuous dynamic recrystallization with bulging grain boundary induced by twinning. The latter mechanism was less dominan

Evaluation of the Success Criteria for Zirconia Dental Implants : A Four-Year Clinical and Radiological Study

Objectives. The aim was to evaluate survival and success rates, soft tissue health, and radiographic marginal bone loss (MBL) of zirconia implants placed in the esthetic and posterior areas of the jaws and in association with multiple or single implant restorations after at least 6 months of definitive restoration. Material and Methods. 35 one-piece zirconium implants were utilized for single or partially edentulous ridges rehabilitation. All implants received immediate temporary restorations and six months after surgery were definitively restored. Every 6 months after implant placement, a clinical-radiographic evaluation was performed. For each radiograph, the measurements of MBL were calculated. Results. The results showed that the mean MBL at 48-month followup was 1.631\u2009mm. The mean MBL during the first year of loading was not more significant for implants placed in the first molar regions than for those positioned in other areas. Moreover, no differences in marginal bone level changes were revealed for multiple and single implants, whereas MBL in the first year was observed to be slightly greater for implants placed in the maxilla than for those placed in the mandible. Conclusion. Zirconia showed a good marginal bone preservation that could be correlated with one-piece morphology and characteristics of zirconia implants

Biomechanical and histological analysis of titanium (machined and treated surface) versus zirconia implant materials: an in vivo animal study

This article belongs to the Special Issue Clinical Implants and the Biocompatibility of Biodegradable BiomaterialsObjectives: The aim of this study was to perform an in vivo histological comparative evaluation of bone formation around titanium (machined and treated surface) and zirconia implants. For the present study were used 50 commercially pure titanium implants grade IV, being that 25 implants with a machined surface (TiM group), 25 implants with a treated surface (TiT group) and, 25 implants were manufactured in pure zirconia (Zr group). The implants (n = 20 per group) were installed in the tibia of 10 rabbits. The implants distribution was randomized (n = 3 implants per tibia). Five implants of each group were analyzed by scanning electron microscopy and an optical laser profilometer for surface roughness characterization. Six weeks after the implantation, 10 implants for each group were removed in counter-torque for analysis of maximum torque value. The remaining samples were processed, included in historesin and cut to obtain non-decalcified slides for histomorphological analyses and histomorphometric measurement of the percentage of bone-implant contact (BIC%). Comparisons were made between the groups using a 5% level of significance (p < 0.05) to assess statistical differences. The results of removal torque values (mean ± standard deviation) showed for the TiM group 15.9 ± 4.18 N cm, for TiT group 27.9 ± 5.15 N cm and for Zr group 11.5 ± 2.92 N cm, with significant statistical difference between the groups (p < 0.0001). However, the BIC% presented similar values for all groups (35.4 ± 4.54 for TiM group, 37.8 ± 4.84 for TiT group and 34.0 ± 6.82 for Zr group), with no statistical differences (p = 0.2171). Within the limitations of the present study, the findings suggest that the quality of the new bone tissue formed around the titanium implants present a superior density (maturation) in comparison to the zirconia implants

Marginal bone level around conical connection tapered implants with platform switching: A multicenter retrospective study at 14 months follow-up

Aim The long-term success of dental implants mainly depends on marginal bone stability around the fixtures. The development of prosthetic abutments with reduced width in relation to the implant prosthetic platform (platform switching) and/or tighter implant/abutment connections seem to have a potential in reducing crestal bone resorption. The aim of the present study was to examine the effect of platform switching and conical connection design, on marginal bone loss around newly designed dental implants. Materials and Methods Subjects who underwent implant therapy in three different centers, were enrolled in the present retrospective study. Patients were rehabilitated with tapered platform-switched dental implants. To evaluate marginal bone level changes over time, the mesial and distal bone height was radiographically evaluated on the day of implant placement (baseline) and 14 months post-implantation. Results One hundred and twelve conical tapered platform-switched implants were placed in three different centers in 37 patients, with mean age of 53 years. The survival rate was 100% after an average follow-up of 14 months. During the first year, marginal bone loss was 0.67±0.45mm. No statistically significant differences were recorded between the different centers. Conclusions Within the limitations of the present retrospective study, limited marginal bone loss and 100% implant survival rate were observed over 14 months of follow-up. The results showed high crestal bone stability around the newly designed conical tapered platform-switched implants

Platform switching in the treatment of Cleidocranial Dysplasia: a case report

Background Cleidocranial dysplasia is a very rare occurrence, its incidence being 1: 1,000,000.Case report This report describes the treatment of a 31-year-old woman with cleidocranial dysplasia treated with expanded platform implants. All mandibular and maxillary teeth were extracted and porcine collagenized bone was used to cover the bone defects in both arches. Six months later, four expanded platform implants were used to restore the mandibular arch, but one of them failed before the prosthesis was placed. In the maxillary arch a complete denture was relined and placed in the maxilla. The definitive mandibular restoration was delivered 3 months after surgery.Conclusion Since early diagnosis of cleidocranial dysplasia is essential for choosing the appropriate treatment approach, clinicians should be aware of its characteristic features

Mechanical, histological and histomorphometric evaluation of modified by femtosecond laser zirconia implants versus titanium implants. An experimental study in dogs at three months

Aim The present study was aimed at quantifying implant´s stability and elemental composition by Periotest® and evaluating bone to implant contact (BIC) and crestal bone loss of modified by femtosecond laser zirconia and titanium implants.Materials and methods Forty-eight implants were divided into 2 groups: titanium (control) and modified by femtosecond laser zirconia (test) and then inserted in 6 American Foxhound dogs. Primary stability and secondary stability were measured by Periotest, BIC was evaluated by histomorphometry at 1 and 3 months, elemental composition of the surrounding bone in both groups after 1 and 3 months was assessed.Results Differences between groups regarding primary stability and secondary stability were not significant (p>0.05). The Carbon ratio at zirconia (12.529%) was significantly lower (p0.05) regarding BIC for titanium vs modified zirconia were observed. Crestal bone loss at 3 months was significantly (p<0.05) lower (0.07 ±0.34 mm) in titanium group than in zirconia (1.25 ± 1.73 mm).Conclusion Surface treatment by using femtosecond laser equalizes osseointegration of zirconia implants