Comparative histological and histomorphometric results of six biomaterials used in two-stage maxillary sinus augmentation model after 6-month healing

To evaluate the performances of six different bone substitute materials used as graft in maxillary sinus augmentation by means of histological and histomorphometric analysis of bone biopsies retrieved from human subjects after a 6-month healing period. Materials and Methods. Six consecutive patients (3 males, 3 females, aged 50-72 years), healthy, nonsmokers, and with good oral hygiene, presenting edentulous posterior maxilla with a residual bone crest measuring ≤ 4 mm in vertical height and 3 to 5 mm in horizontal thickness at radiographic examination, were selected to receive sinus augmentation and delayed implant placement. Under randomized conditions, sinus augmentation procedures were carried out using mineralized solvent-dehydrated bone allograft (MCBA), freeze-dried mineralized bone allograft (FDBA), anorganic bovine bone (ABB), equine-derived bone (EB), synthetic micro-macroporous biphasic calcium-phosphate block consisting of 70% beta-tricalcium phosphate and 30% hydroxyapatite (HA-β-TCP 30/70), or bioapatite-collagen (BC). After 6 months, bone core biopsies were retrieved and 13 implants were placed. Bone samples were processed for histological and histomorphometric analysis. CT scans were taken before and after surgery. After 4 months of healing, patients were restored with a provisional fixed acrylic resin prosthesis, as well as after further 2-4 months with a definitive cemented zirconia or porcelain-fused-to-metal crowns. Results. There were no postoperative complications or implant failures. The histological examination showed that all biomaterials were in close contact with newly formed bone, surrounding the graft granules with a bridge-like network. No signs of acute inflammation were observed. The histomorphometry revealed 20.1% newly formed bone for MCBA, 32.1% for FDBA, 16.1% for ABB, 22.8% for EB, 20.3% for HA-β-TCP 30/70, and 21.4% for BC. Conclusions. Within the limitations of the present investigation, all the six tested biomaterials showed good biocompatibility and osteoconductive properties when used in sinus augmentation procedures, although the FDBA seemed to have a better histomorphometric result in terms of newly formed bone and residual graft material. This trial is registered with ClinicalTrials.gov Identifier (Registration Number): NCT03496688

Maxillary sinus augmentation in humans using cortical porcine bone: a histological and histomorphometrical evaluation after 4 and 6 months

Background: Bone substitutes, such as allografts, xenografts, and alloplasts, have been proposed in several augmentation procedures. Purpose: The aim of the present study was a histologic and histomorphometric evaluation of specimens retrieved 4 or 6 months after sinus augmentation using cortical porcine bone augmentation material. Materials and Methods: A total of 77 specimens, retrieved after 4 and 6 months from augmented sinuses, were used in this study. The specimens were processed to be observed under light microscopy. Histomorphometric measurements were presented as means 1 standard deviations. Results: Most of the particles were surrounded by newly formed bone with large osteocyte lacunae. Histomorphometry showed that, after 4months, the newly formed bone represented 28%, marrow spaces 36%, the residual graft material 37%, while, after 6 months, the newly formed bone represented 31%, marrow spaces 34%, while the residual graft material was 37%. Conclusion: The present results show that cortical porcine bone is a biocompatible, osteoconductive biomaterial that ca

The symmetric 3D organization of connective tissue around implant abutment: a key-issue to prevent bone resorption

Symmetric and well-organized connective tissues around the longitudinal implant axis were hypothesized to decrease early bone resorption by reducing inflammatory cell infiltration. Previous studies that referred to the connective tissue around implant and abutments were based on two-dimensional investigations; however, only advanced three-dimensional characterizations could evidence the organization of connective tissue microarchitecture in the attempt of finding new strategies to reduce inflammatory cell infiltration. We retrieved three implants with a cone morse implant–abutment connection from patients; they were investigated by high-resolution X-ray phase-contrast microtomography, cross-linking the obtained information with histologic results. We observed transverse and longitudinal orientated collagen bundles intertwining with each other. In the longitudinal planes, it was observed that the closer the fiber bundles were to the implant, the more symmetric and regular their course was. The transverse bundles of collagen fibers were observed as semicircular, intersecting in the lamina propria of the mucosa and ending in the oral epithelium. No collagen fibers were found radial to the implant surface. This intertwining three-dimensional pattern seems to favor the stabilization of the soft tissues around the implants, preventing inflammatory cell apical migration and, consequently, preventing bone resorption and implant failure. This fact, according to the authors’ best knowledge, has never been reported in the literature and might be due to the physical forces acting on fibroblasts and on the collagen produced by the fibroblasts themselves, in areas close to the implant and to the symmetric geometry of the implant itself

Xeno-Hybrid composite scaffold manufactured with CAD/CAM technology for horizontal bone-augmentation in edentulous atrophic maxilla: a short communication

Abstract: The present short communication described a new procedure for the reconstruction of the horizontal severely resorbed edentulous maxilla with custom-made deproteinized bovine bone block, fabricated using three-dimensional imaging of the patient and computer-aided design/computer-aided manufacturing (CAD/CAM) technology. The protocol consisted of three phases. In the diagnosis and treatment planning, cone-beam computed tomographic scans of the patient were saved in DICOM (digital imaging and communication in medicine) format, anatomic and prosthetic data were imported into a dedicated diagnostic and medical imaging software, the prosthetic-driven position of the implants, and the graft blocks perfectly adapted to the residual bone structure were virtually planned. In the manufacturing of customized graft blocks, the CAD-CAM technology and the bovine-derived xenohybrid composite bone (SmartBone® on Demand - IBI SA - Industrie Biomediche Insubri SA Switzerland) were used to fabricate the grafts in the exact shape of the 3D planning virtual model. In the surgical and prosthetic procedure, the maxillary ridge augmentation with custom-made blocks and implant-supported full-arch screw-retained rehabilitation were performed. The described protocol offered some advantages when compared to conventional augmentation techniques. The use of deproteinized bovine bone did not require additional surgery for bone harvesting, avoided the risk of donor site morbidity, and provided unlimited biomaterial availability. The customization of the graft blocks reduced the surgical invasiveness, shorting operating times because the manual shaping of the blocks and its adaptation at recipient sites are not necessary and less dependent on the clinician’s skill and experience

Comparative In Vitro Evaluation of the Primary Stability in D3 Synthetic Bone of Two Different Shapes and Pitches of the Implant Threads

Background: Implant primary stability can be affected by several factors related to implant macrogeometry, local anatomy, and surgical techniques. The aim of this research was to study primary stability on polyurethane foam sheets of wide‐threaded implant design compared to narrow‐threaded implants. Materials and methods: Two different implant designs were positioned on D3 density polyurethane blocks in a standardized environment: the wide‐threaded implant and the narrow‐threaded implant, for a total of 160 specimens. Moreover, for each group, two different sizes were considered: 3.8mm × 12mm and 4.8mm × 12 mm. The insertion torque (IT) values, the removal strength (RT), and the Periotest analyses were evaluated. Results: A significantly higher IT and RT was reported for wide‐threaded implants and two‐stage implants (p < 0.01), compared to the narrow‐threaded implants. The diameters seemed to provide a significant effect on the primary stability for both implants’ geometry (p < 0.01). A higher mean of the one‐stage implant was evident in the Periotest measurements (p < 0.01). Conclusions: Both of the implants showed sufficient stability in polyurethane artificial simulation, while the wide‐threaded implant design showed a higher primary stability on alveolar cancellous synthetic bone in vitro. Additionally, the prosthetic joint connection seemed to have a determinant effect on Periotest analysis, and the one‐stage implants seemed to provide a high stability of the fixture when positioned in the osteotomy, which could be important for the immediate loading protocol

A site-specific intraoperative measurement of bone-to-implant contact during implant insertion: A study on bovine ribs using a computerized implant motor

Background/purpose: The aim of the current in vitro study was to determine if there was a correlation between the integrals (I) of the function cutting resistance/depth, obtained using a computerized implant motor, and the bone-to-implant contact (BIC) percentages of dental implants inserted in bovine ribs. Materials and methods: Segments of bovine ribs were used, and a total of 21 perforations were performed. A total of 21 dental implants were inserted in the prepared bone sites. A computerized implant motor ("Torque Measuring Motor") was used to assess, before implant insertion, the values of the bone cutting resistance. The data of bone density obtained by the implant motor were statistically correlated with the BIC percentages. Results: A significant positive linear correlation was found between the integrals measured by the implant motor and the BIC assessed by histomorphometry (r = 0.78, n = 21, P < 0.0001). Indeed, the increase of the integral values recorded by the reader matched with the increase of BIC percentages measured by histomorphometry. Pearson correlation coefficient for linear regression (R2) between values assessed by the surgical motor and histomorphometry was 0.61 (P < 0.0001), indicating that 61% of the data points were aligned with the regression line. Conclusion: The instrument under testing seems to provide a reliable quantitative estimator, the integral, of the final BIC achieved at implant insertion, and therefore of the implant primary stability, and could represent a significant aid for a proper planning of rehabilitations with the use of dental implants

S100A8 calcium-binding expression in radicular and dentigerous cysts and in keratocystic odontogenic tumors

Introduction: Recently the term Keratocystic Odontogenic Tumor (KCOT) has been recommended for Odontogenic Keratocysts (OKC) to address the neoplastic nature of the lesion compared to radicular and dentigerous cysts. S100 are calcium-binding proteins involved in cell differentiation and inflammation, with a potential role in neoplastic transformation. Aim: The aim of this study was to evaluate whether S100A8 protein expression is different in KCOT compared to radicular cysts (RC) and dentigerous cysts (DC). Methods: A total of 84 consecutive odontogenic cysts, 34 RC, 25 DC, and 25 KCOT, were analyzed in this study. Results: Epithelial cells in KCOT cases were not immunoreactive for S100A8 except focally in cases associated with inflammation, while RC cases showed a variable positivity of all the epithelial layers from the basal to the superficial in 19/34 cases and DC cases showed a weak positivity of the intermediate and superficial layers in 7/25 cases. Conclusion: The lack of S100A8 protein expression seems to be observed more frequently in KCOT compared to RC and DC. This difference might be related to their neoplastic nature and a potential aggressive biological behavior for odontogenic cystic lesions

Histomorphometric and Clinical Analysis of Ridge Preservation Procedures in Extraction Sockets with Buccal Bone Defects (>5mm) Using an In Situ Hardening Biphasic Calcium Phosphate (HA/β-TCP) Graft and a Bioresorbable Matrix: A Human Study at 6 Months

Many biomaterials have been proposed for ridge preservation techniques to counteract fresh extraction socket resorption. The primary aim of this prospective single cohort study was to evaluate the histomorphometric outcomes of a synthetic biphasic calcium phosphate (60% HA/40% β-TCP) and a synthetic poly-lactic acid membrane, used to graft fresh extraction socket sites with a full or partial (>5mm) resorption of the buccal bone plate. Patients recruited were treated at one esthetic site with a ridge preservation procedure to receive an implant-supported prosthesis. After 6 months of healing, a bone biopsy was harvested. Outcome evaluations were: biological complications, histomorphometrical analysis, and alveolar horizontal and vertical bone loss (∆AHB, ∆AVB). Thirteen subjects were included in this study. Two cases of biological complication were recorded. All 13 patients received implant insertion. From histomorphometric analysis, a mean of 48.9 ± 11.9%, 29.0 ± 9.3%, and 22.0 ± 9.7% was recorded for soft tissues, new bone, and residual graft particles, respectively. From clinical analysis, a mean of 0.5 ± 1.0 mm (p-value < 0.05) and 0.9 ± 1.3 mm (p-value < 0.05) was recorded for alveolar horizontal and vertical bone loss, respectively. In conclusion, this prospective cohort study showed encouraging results in preserving alveolar ridge dimension. A moderate percentage of new bone and an acceptable alveolar ridge loss were achieved at a 6 month follow-up

Osteoblasts and Fibroblasts Interaction with a Porcine Acellular Dermal Matrix Membrane

The use of collagen membranes has remained the gold standard in GTR/GBR. In this study, the features and the biological activities of an acellular porcine dermis collagen matrix membrane applicable during dental surgery were investigated, and also by applying hydration with NaCl. Thus, two tested membranes were distinguished, the H-Membrane and Membrane, compared to the control cell culture plastic. The characterization was performed by SEM and histological analyses. In contrast, the biocompatibility was investigated on HGF and HOB cells at 3, 7, and 14 days by MTT for proliferation study; by SEM and histology for cell interaction study; and by RT-PCR for function-related genes study. In HOBs seeded on membranes, mineralization functions by ALP assay and Alizarin Red staining were also investigated. Results indicated that the tested membranes, especially when hydrated, can promote the proliferation and attachment of cells at each time. Furthermore, membranes significantly increased ALP and mineralization activities in HOBs as well as the osteoblastic-related genes ALP and OCN. Similarly, membranes significantly increased ECM-related and MMP8 gene expression in HGFs. In conclusion, the tested acellular porcine dermis collagen matrix membrane, mainly when it is hydrated, behaved as a suitable microenvironment for oral cells

In Vivo Regenerative Properties of Coralline-Derived (Biocoral) Scaffold Grafts in Human Maxillary Defects: Demonstrative and Comparative Study with Beta-Tricalcium Phosphate and Biphasic Calcium Phosphate by Synchrotron Radiation X-Ray Microtomography

Background: In recent years, there has been interest on the fabrication of systems using particulates or block-based approach for bone tissue engineering (TE) scaffolds, possessing porous interconnected structures. In fact, these particular morphologies greatly increase the surface area for more chemical and biological reactions to take place. Purpose: This study was designed to demonstrate the unique capability of the synchrotron radiation x-ray microtomography (micro-CT) in offering an advanced characterization of coralline-derived (Biocoral) biomaterials placed in human maxillary defects as it allows, in a nondestructive way, a complete, precise, and high-resolution three-dimensional analysis of their microstructural parameters. Moreover, the comparison between Biocoral and other biomaterials was explored to understand the mechanism of their biological behavior as bone substitute. Materials and Methods: Implant survival, bone regeneration, graft resorption, neovascularization, and morphometric parameters (including anisotropy and connectivity index of the structures) were evaluated by micro-CT in Biocoral and the other biomaterials after 6 to 7 months from implantation in human maxillary bone defects. Results: After the in vivo tests, a huge amount of bone was detected in the retrieved Biocoral-based samples, coupled with a good rate of biomaterial resorption and the formation of a homogeneous and rich net of new vessels. The morphometric parameters were comparable to those obtained in the biphasic calcium phosphate-based control, with the exception of the connectivity index for which this control exhibited the most well-connected structure. This last result, together with those referred to the poor performances of the b-tricalcium phosphate block-based sample, suggests that the particular scaffold morphology may play a role in the hunt the optimal scaffold structure to be implanted. Conclusion: In this limited study, implant success rate seems not strictly dependent on the biomaterial that is used, but on the scaffold morphology. Micro-CT technique was demonstrated to play a fundamental role in advanced characterization of bone TE constructs