Daniela Carmagnola

Oral implants placed in bone defects treated with Bio‐Oss®, Ostim®‐Paste or PerioGlas: an experimental study in the rabbit tibiae

OBJECTIVES To compare the histological features of bone filled with Bio-Oss, Ostim-Paste or PerioGlas placed in defects in the rabbit tibiae by evaluating bone tissue composition and the integration of titanium implants placed in the grafted bone. MATERIAL AND METHODS Two cylindrical bone defects, about 4 mm in diameter and 6 mm in depth, were created in the tibiae of 10 rabbits. The defects were filled with either Bio-Oss, PerioGlas, Ostim-Paste or left untreated, and covered with a collagen membrane. Six weeks later, one titanium sandblasted and acid-etched (SLA) implant was inserted at the centre of each previously created defect. The animals were sacrificed after 6 weeks of healing. RESULTS Implants placed in bone previously grafted with Bio-Oss, PerioGlas or Ostim-Paste obtained a larger extent of osseointegration, although not statistically significant, than implants placed in non-grafted bone. The three grafting materials seemed to perform in a similar way concerning their contribution towards implant osseointegration. All grafting materials appeared to be osteoconductive, thus leading to the formation of bridges of mineralized bone extending from the cortical plate towards the implants surface through the graft scaffold. CONCLUSIONS Grafting with the above-mentioned biomaterials did not add any advantage to the osseointegration of titanium SLA implants in a self-contained defect.

Dental and periodontal history of oncologic patients on parenteral bisphosphonates with or without osteonecrosis of the jaws: A pilot study

OBJECTIVES We tested the hypothesis that patients on bisphosphonates with ONJ might have a poorer dental and periodontal history than non-ONJ patients. Our aim was to retrospectively compare medical and oral history of patients on bisphosphonates with and without ONJ. STUDY DESIGN A total of 39 oncologic patients on bisphosphonates were interviewed, examined, and had a panoramic radiograph taken. DMFT values and residual bone levels were calculated and compared for ONJ and non-ONJ patients. RESULTS Twenty of 39 patients had ONJ. No statistical differences in caries or residual bone level as well as dental extractions were detected, although twice as many patients with ONJ underwent dental extractions. ONJ patients had received statistically more administrations of bisphosphonates compared to non-ONJ patients. CONCLUSION A long history of bisphosphonate administration might represent a risk for ONJ onset.

Histological findings on jaw osteonecrosis associated with bisphosphonates (BONJ) or with radiotherapy (ORN) in humans.

Abstract Objective. To describe the histological features of bone tissue harvested from patients affected by jaw osteonecrosis associated with bisphoshponates (BONJ) or with radiotherapy (ORN), in undecalcified ground sections. Materials and methods. Sixteen bone tissue samples from 14 patients with BONJ and two patients with ORN were processed in order to obtain both ground, undecalcified sections and decalcified sections. The sections underwent histometric and morphometric analysis. Results. Bone tissue samples obtained from patients with BONJ or ORN of the jaws shared some histological characteristics. Common histological features included the loss of bone architecture, the absence of a proper Haversian system and proper marrow spaces, the presence of necrotic spots of non-mineralized tissue, areas of empty osteocytic lacunae next to areas of hypercellularity, the presence of resorption pits with rare osteoclast-like cells and the presence of bacteria and of an inflammatory infiltrate. A violet rib of tissue characterized by large resorption pits facing was frequently observed between the mineralized bone and the inflammatory infiltrate. Conclusions. The histological features of BONJ and ORN are similar and resemble those of osteomyelitis. Even though it is not clear whether infection is the cause or consequence of bone exposure, inflammatory cells, bacteria or their products may have a massive, direct lytic effect on bone tissue challenged by bisphosphonates.

Iliac Crest Fresh-Frozen Allografts Versus Autografts in Oral Pre-Prosthetic Bone Reconstructive Surgery : Histologic and Histomorphometric Study

Purpose:The aim of this work was to compare histologically bone biopsies obtained during dental implant placement in atrophic jaws reconstructed with fresh-frozen bone (FFB) or autologous bone blocks. Materials and Methods:Twenty partially or totally edentulous patients were treated either with iliac crest FFB grafts (14 patients; group A) or with iliac crest autografts (6 patients; group B). Seven to 9 months later, dental implants were placed in the reconstructed jaws and bone biopsies were harvested. Results:The reconstructive procedure was uneventful in 9 patients of group A and in all patients of group B. Samples from both groups did not show relevant differences concerning the proportion of lamellar bone, newly formed bone, and bone marrow. In group A, the decreasing proportion of blood vessels from the apical to the coronal portion, the larger amount of lacunae in the apical portion, and the fewer vessels in the coronal portion than in group B evoke an effort of the host bone to “integrate” the graft from the apical portion. Conclusions:FFB cannot be considered as successful and safe in alveolar bone reconstruction as autogenous bone grafting.

Histologic and immunohistochemical description of early healing at marginal defects around implants.

This study reports on the histologic characteristics of the early phases of implant osseointegration, focusing on osteopontin concentrations in the coronal area of implants placed with marginal defects and in control sites without defect preparation. In the mandibular right area of 12 dogs, two recipient sites were prepared and the margins were widened to obtain a gap of 0.5 mm at one site (small defect) and 1.25 mm at another site (large defect). Implants were placed and allowed a fully submerged healing. The procedure was subsequently performed in the left side in such a way as to obtain healing times of 5, 10, 20, and 30 days. Paraffin sections were stained with osteopontin antibodies and analyzed. At control implants, scarcely organized collagen fibers were observed in the space between the pristine bone and implant and were quickly replaced by mineralized tissue. In the small and large defects, the collagen fibers were organized in a layer that ran parallel to the implant at day 10 and became denser and thicker with time. Osteopontin was evenly distributed in the peri-implant tissue at control implants, while it was mainly located in the collagen bundle section around the implants placed in the defects.The complexity and labor-intensive nature of making implant-level impressions may inhibit some clinicians from recommending dental implant treatment. This paper describes a simplified impression technique for fabricating anatomical, cement-retained abutments without removing or inserting implant components. Using digitally coded healing abutments, this protocol bridges the gap between traditional impressions and computer-aided abutment manufacturing. Basic logistic considerations are reviewed, as well as other biomechanic and esthetic advantages, that should optimize overall treatment outcomes.

Histological evaluation of the peri-implant tissues of three human-retrieved Straumann implants

The most frequently-used histological parameters to define dental implant osseointegration include bone-to-implant contact and quantitative and qualitative assessments of the surrounding tissue (rate of mineralized/non-mineralized tissue and proportion of lamellar and woven bone compared to soft tissue or bone marrow). The aim of this paper was to present the histological features of the bone tissue surrounding three well-functioning Straumann SLA and SLActive implants placed in two patients after 12 and 60 months of loading. The percentage of osseointegration ranged from 66.4% and 71.9% for SLA surfaces, to 88.3% for the SLActive implant. Such results confirm that osseointegration occurs with high rates of bone-to-implant contact in humans, and that implants can be similarly clinically successful, although they show different bone-to-implant contact values.

Dental treatment of a rare case of pyoderma gangrenosum with aggressive periodontal disease

BACKGROUND AND OVERVIEW Pyoderma gangrenosum (PG) is a rare neutrophil-mediated autoinflammatory dermatosis that can involve the oral mucosa. Dental surgery is a potential triggering factor for the onset of PG lesions. The authors describe and discuss the dental management of a rare case of aggressive periodontitis in a patient with PG, from multiple tooth extractions to prosthetic rehabilitation, including administration of systemic steroid prophylaxis before surgery to prevent the potential onset of PG-related lesions. CASE DESCRIPTION A 22-year-old man who had a diagnosis of PG and who had aggressive periodontal disease underwent dental extractions, gingivoplastic surgery, and prosthetic rehabilitation. The patient received 8 milligrams of betamethasone intramuscularly 20 minutes before the oral surgery. The tissues healed perfectly, and no adverse effects were reported. CONCLUSIONS AND PRACTICAL IMPLICATIONS For minor oral surgery, prophylactic corticosteroids might help reduce the risk of developing PG-related lesions. The clinician should plan the prosthetic devices to be as atraumatic as possible.

Engineered scaffolds and cell-based therapy for periodontal regeneration

Background The main objective of regenerative periodontal therapy is to completely restore the periodontal tissues lost. This review summarizes the most recent evidence in support of scaffold- and cell-based tissue engineering, which are expected to play a relevant role in next-generation periodontal regenerative therapy. Methods A literature search (PubMed database) was performed to analyze more recently updated articles regarding periodontal regeneration, scaffolds and cell-based technologies. Results Evidence supports the importance of scaffold physical cues to promote periodontal regeneration, including scaffold multicompartmentalization and micropatterning. The in situ delivery of biological mediators and/or cell populations, both stem cells and already differentiated cells, has shown promising in vivo efficacy. Conclusions Porous scaffolds are pivotal for clot stabilization, wound compartmentalization, cell homing and cell nutrients delivery. Given the revolutionary introduction of rapid prototyping technique and cell-based therapies, the fabrication of custom-made scaffolds is not far from being achieved.

Histomorphometrical evaluation of the effects of Aminogam® gel in oral healing process of post-surgical soft tissue

Wound healing is a dynamic process that involves a complex interaction of inflammatory cells, cytokines and mediators of extracellular matrix [1]. One of the processes that occur during tissue regeneration is angiogenesis and it is considered to have a pivotal role in wound repair. Previous studies have shown that a topical application of proteins and sodium hyaluronate to wounds can expedite the repair of damaged tissue [2]. The aim of this preliminary study is to evaluate the efficacy of Aminogam® gel (A®) (ErreKappa Euroterapici SpA, Milano), a topical medication which contains 4 amino acids (glycine, leucine, proline, lysine) and sodium hyaluronate, used to improve and accelerate gingival flap healing following molar extraction by analyzing collagen fibers amount, orientation and microvascular distribution (MVD). Ten patients (mean age 49ys) were included in the study. Two teeth (38 and 48) were extracted at an interval of 30 days. The “test” site (AM) was treated with A® while the “control” site (no AM) was not. Dental extraction was performed and the flaps were sutured with a consequent excess of tissue for histological processing (T0). A® had been applied only at the AM site for 10 days post-extraction. At suture removal, a gingivoplasty was performed and the exceeding tissue was histologically analysed (T1). Paraffin blocks were cut and slides were stained with haematoxylin-eosin and Sirius Red. No signs of inflammatory infiltrate or necrosis were observed. Sirius Red staining highlighted a lower degree of organized collagen fibers at T1 vs T0. At T0 the fibers were organized in closely packed and well-oriented bundles. At T1-no AM fibers were thin and formed a disorganized grid. At T1-AM fibers appeared thicker and the tissue appeared more mature compared to T1-no AM. Immunohistochemistry against CD31 was performed to mark endothelial cells and to calculate MVD by stereological method [3]. MVD resulted highest at T1-AM. The T1 data normalized on T0 presented a statistically significant difference (p=0.012) between AM and no AM group. In conclusion, A® gel seems to increase new blood vessels formation and to promote collagen deposition and organization.

Human Adipose-Derived Stem Cells on Rapid Prototyped Three-Dimensional Hydroxyapatite/Beta-Tricalcium Phosphate Scaffold

Abstract In the study, we assess a rapid prototyped scaffold composed of 30/70 hydroxyapatite (HA) and beta-tricalcium-phosphate (&bgr;-TCP) loaded with human adipose-derived stem cells (hASCs) to determine cell proliferation, differentiation toward osteogenic lineage, adhesion and penetration on/into the scaffold. In this in vitro study, hASCs isolated from fat tissue discarded after plastic surgery were expanded, characterized, and then loaded onto the scaffold. Cells were tested for: viability assay (Alamar Blue at days 3, 7 and Live/Dead at day 32), differentiation index (alkaline phosphatase activity at day 14), scaffold adhesion (standard error of the mean analysis at days 5 and 18), and penetration (ground sections at day 32). All the hASC populations displayed stemness markers and the ability to differentiate toward adipogenic and osteogenic lineages. Cellular vitality increased between 3 and 7 days, and no inhibitory effect by HA/&bgr;-TCP was observed. Under osteogenic stimuli, scaffold increased alkaline phosphatase activity of +243% compared with undifferentiated samples. Human adipose-derived stem cells adhered on HA/&bgr;-TCP surface through citoplasmatic extensions that occupied the macropores and built networks among them. Human adipose derived stem cells were observed in the core of HA/&bgr;-TCP. The current combination of hASCs and HA/&bgr;-TCP scaffold provided encouraging results. If authors’ data will be confirmed in preclinical models, the present engineering approach could represent an interesting tool in treating large bone defects.