Albumin-impregnated bone granules modulate the interactions between mesenchymal stem cells and monocytes under in vitro inflammatory conditions

Bone regeneration around newly implanted biomaterials is a complex process, which in its early phases involves the interactions between Mesenchymal Stem Cells (MSCs) and immune cells. The response of these cells to the biomaterial depends both on the local microenvironment and on the characteristics of the inserted bone substitute. In this work, bone allografts impregnated with albumin are loaded with a co-culture of human MSCs and monocytes; bone granules without albumin are used for comparison. Co-cultures are contextually treated with pro-inflammatory cytokines to simulate the inflammatory milieu naturally present during the bone regeneration process. As revealed by microscopic images, albumin-impregnated bone granules promote adhesion and interactions between cells populations. Compared to control granules, albumin coating diminishes reactive species production by cells. This reduced oxidative stress may be attributable to antioxidant properties of albumin, and it is also reflected in the mitigated gene expression of mitochondrial electron transport chain complexes, where most intracellular reactive molecules are generated. MSCs-monocytes co-cultured onto albumin-impregnated bone granules additionally release higher amounts of immunomodulatory cytokines and growth factors. In summary, this work demonstrates that impregnation of bone granules with albumin positively modulates the interactions between MSCs and immune cells, consequently influencing their mutual activities and immunomodulatory functions

Crestal sinus lift using an implant with an internal L-shaped channel : 1-year after loading results from a prospective cohort study

Purpose: To evaluate the clinical and radiographic outcomes of a one-stage crestal sinus elevation procedure using a self-tapping endosseous implant system (iRaise, Maxillent, Herzliya, Israel) developed for sinus augmentation, 1 year after loading. Materials and methods: Patients needing restoration in the posterior maxilla with a residual alveolar crest of 3 to 8 mm in height and 5 mm in width distal to the canine as measured on CBCT scan were treated using the iRaise sinus lift system. Outcome measures were: implant and prosthetic failures, any complications, increased bone height (iBH), marginal bone loss (MBL), implant stability quotient (ISQ), radiographic tissue remodelling patterns using the sinus grafting remodelling index (SGRI), volumetric measurements of sinus graft, patient self-reported post-surgical swelling, consumption of pain medication and histological analysis. Results: A total of 30 consecutive participants with a mean age of 54.2 ± 9.4 years underwent a transcrestal elevation of the sinus membrane, insertion of bone graft, and implant placement. A total of 50 implants were placed (30 iRaise system implants and 20 adjunctive iSure implants, Maxillent). The mean follow-up was 15.8 ± 2.1 months after implant loading. One patient dropped out at the 1-year after loading follow-up examination. No implants and no prostheses failed during the entire follow-up. One patient experienced a small membrane tear. Before implant insertion, the mean residual alveolar ridge height was 4.64 ± 0.86 mm (range: 3.4-6.4 mm; 95% CI: 4.39-5.01 mm). One year after loading, the bone height was 16.86 ± 3.13 mm (95% CI 15.83-18.07 mm). At the 1-year after loading follow-up, the mean MBL was 0.19 ± 1.05 mm (95% CI 0.02-0.78 mm). The mean ISQ at implant placement was 65.2 ± 5.4 (95% CI 63.6-67.4) and increased during the healing period reaching the mean value of 73.6 ± 3.7 (95% CI 73.1-75.9; range 62-79). The difference was statistically significant (8.4 ± 5.3; 95% CI 5.9-39.7; P = 0.0000). One year after loading, SGRI score was evaluated in 23 implants. Overall, the mean SGRI value was 2.29 ± 2.41 mm (95% CI 1.22-2.98 mm). Bone volume at implant placement was 2.41 ± 0.25 CC (95% CI 2.22-2.48 CC). During the 6-month, submerged healing period, a slight bone contraction of 11.3% were observed. (2.13 ± 0.24 CC;95% CI 2.02-2.26; difference = 0.27 ± 0.25 CC; 95% CI 0.10-0.36; P = 0.0011). At the first year post-loading period, the bone graft remained stable (2.11 ± 0.22 CC; 95% CI 2.02-2.24). The difference was not statistically significant (0.02 ± 0.07 CC; 95% CI 0.01-0.04; P = 0.2166). From the patient's point of view, the mean pain value was 0.52 ± 0.74 (range 0-3); mean swelling value was 0.27 ± 0.52 (range 0-2); and the mean consumption of analgesic was 0.87 ± 4.94 tablets (range 0-4) 3 days after surgery. Morphological and histomorphometric analyses showed that all the samples had a normal structure without inflammatory infiltrate, six months after healing. The following fractions (%) were found: bone (immature bone + mature bone): 44.07 ± 4.91; residual biomaterial: 23.98 ± 2.64; medullary spaces: 31.95 ± 3.16. Conclusions: Sinus floor augmentation can be successfully accomplished with a transcrestal approach using a dedicated implant system. A physiologic contraction of 11.3% of the original volume of the bone graft was experienced during the first 6 months of healing; afterwards, no additional graft volume reduction was observed. Long-term clinical studies are needed to confirm these preliminary results

Three-Dimensional Assessment of Volumetric Changes in Sinuses Augmented with Two Different Bone Substitutes

Introduction. The bone volume of the posterior maxilla may not be appropriate for implant placement, due to factors such as pneumatized maxillary sinus. The purpose of this study was to evaluate the percentage of graft volume reduction following sinus floor elevation (SFE), with either slow resorbable bone substitute only or a composite of slow and fast resorbable bone substitutes, using cone beam computed tomography (CBCT). Materials and Methods. In this retrospective study, CBCT scans of SFE procedures were evaluated to determine the volume of grafted sinus with either deproteinized bovine bone (DBB) or a 2 : 1 mixture of biphasic calcium sulfate (CS) and DBB, as a composite. The volumetric changes of sinus augmentations were measured 2 weeks (V-I) and 6 months (V-II) after operation. Results. Thirty-three patients were included in this study. The average percentage volume reduction was 9.39±3.01% and 17.65±4.15% for DBB and composite grafts, respectively. A significant graft volume reduction was observed between V-I and V-II for both groups (p<0.01). The DBB group exhibited significantly less volume reduction than the composite group (p<0.01). Conclusions. Augmented sinus volume may change before implant placement. DBB offers greater volume stability during healing than composite grafts

Histologic and Radiographic Characteristics of Bone Filler Under Bisphosphonates

BACKGROUND: Dental implants and bone augmentation are well-established procedures used for oral rehabilitation. There is an increasing interest in biological mediators used topically for prevention of bone resorption maybe enhancement of osseointegration of dental implants. The purpose of the manuscript is to describe preliminarily the effect of bisphosphonates on the ossification pattern of bone grafts in a rat model. MATERIAL AND METHODS: Twenty Wistar-derived male rats were divided into 2 groups study and control. Bone substitute was added to mandibular defects and was covered by a resorbable collagen membrane. In the study group, the membrane was soaked with bisphosphonates suspension. In the control group, the membrane was soaked with saline solution. Radiographic and histomorphometric evaluation were performed. RESULTS: Radiographically, it was found that bone density was significantly higher in the study group. Histomorphometric analysis revealed a trend of higher bone volume fraction along with reduced bone substitute volume fraction in the study group, and increased number of osteoclasts and blood vessels in the control group. CONCLUSIONS: Within the limitations of our study it was found that there is a trend of increasing bone quantity and radiographic bone density by application of bisphosphonates

Histologic, Histomorphometric, and Clinical Analysis of the Effects of Growth Factors in a Fibrin Network Used in Maxillary Sinus Augmentation

This randomized controlled clinical trial evaluated the effect of mineralized plasmatic matrix (MPM), comprised of synthetic graft and platelet concentrates, on new bone formation and volume stability over time in maxillary sinus lifting (MSL). Unilateral MSL was performed in 20 patients with either beta-tricalcium phosphate (beta-TCP) or MPM grafts (10 sinuses each). Six months postsurgery, specimens were obtained with a trephine bur prior to implant placement in 39 cases. Volumetric changes in sinus augmentation were analyzed between 1 week (T-I) and 6 months (T-II) postsurgery. Histomorphometric and histological analyses of biopsy samples revealed mean new bone percentages of 35.40% +/- 9.09% and 26.92% +/- 7.26% and residual graft particle areas of 23.13% +/- 6.16% and 32.25% +/- 8.48% in the MPM and beta-TCP groups, respectively (p 0.05). Graft reductions between baseline and 6-months postprocedure in the beta-TCP and MPM groups were 17.12% +/- 13.55% and 14.41% +/- 12.87%, respectively, with significant graft volume reduction observed in both groups (p 0.05). Thus, MPM, representing growth factors in a fibrin network, increases new bone formation and has acceptable volume stability in MSL procedure

Transition from hopeless dentition to full-arch fixed-implant-supported rehabilitation by a staged extraction approach: rationale and technique.

Transition from a hopeless dentition to a fixed-implant-supported full-arch reconstruction can be difficult for patients if wearing a transitional removable denture is involved. In addition, an increased risk for trauma to bone augmentation areas and to the implant-bone interface exists when using a removable transitional complete denture during the implant healing period; such risk can compromise implant success or increase crestal bone loss around implants before the final restoration. This article describes a treatment approach that allows replacement of the hopeless dentition with an osseointegrated fixed prosthesis, without rendering the patient totally edentulous before the delivery of the final implant-supported prosthesis. A staged approach using a few hopeless teeth to support a provisional fixed restoration during the healing process can help avoid discomfort and improve implants' outcome. A treatment plan for a maxillary arch reconstruction is used to illustrate the staged approach protocol. This protocol addresses patients' psychologic need to remain dentate during partial or full-mouth rehabilitation, while providing good esthetics and function during restoration of a dental arch

Predictability of Mandibular Autorotation After Le Fort I Maxillary Impaction in Case of Vertical Maxillary Excess

A retrospective study of 20 patients treated for vertical maxillary excess between 2009 and 2010, solely by superior surgical repositioning of the maxilla. Clinical and radiological cephalometric parameters were analyzed statistically and their impact on achieving the predicted postoperative mandibular autorotation and on relapse. According to our study, patients presenting with an anterior open bite and a low occlusal plane angle might fail to achieve the predicted mandibular autorotation and are prone to postoperative relapse. No correlation was found between the extent of maxillary impaction and the presence of autorotation