Biomedical subjects
Adriano Piattelli
Publications and source records attributed to Adriano Piattelli.
Zebra XXV, Part 2. Cemento-ossifying fibroma.
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Microvessel density in alveolar ridge regeneration with autologous and alloplastic bone.
PURPOSE: The purpose of this study was to conduct a comparative immunohistochemical evaluation of microvessel density (MVD) in alveolar sites augmented with autologous bone or Bio-Oss. MATERIALS AND METHODS: Eighteen patients participated in this study. All patients presented maxillary ridge defects. These defects were filled in a random fashion with autologous bone or Bio-Oss. Endosseous implants were inserted after a mean of 3 months in the sites augmented with autologous bone and after a mean of 6 months in the sites augmented with Bio-Oss. As part of the implant site preparation, a trephine was used to harvest bone cores. As control, bone cores retrieved in nonaugmented sites were used. The mean value of MVD in control bone was 25.6 +/- 3.425. In the sites augmented with autologous bone, the MVD was 29.8 +/- 4.4, while in the sites regenerated with Bio-Oss, the MVD was 29.7 +/- 2.4. The statistical analysis showed that the difference in MVD between control bone and autologous bone (P = 0.057) and between control bone and Bio-Oss (P = 0.023) was statistically significant. The difference between the sites regenerated with autologous bone and those regenerated with Bio-Oss was not significant (P = 0.6889). CONCLUSIONS: Our results show that both sites augmented with autologous bone and Bio-Oss presented a higher and statistically significant quantity of microvessels compared with control specimens. No significant differences were found when comparing the MVD of the sites regenerated with autologous bone and those regenerated with Bio-Oss. The retrieval time was, however, a mean of 3 months for the autologous bone sites and a mean of 6 months for the Bio-Oss sites. These data could support the hypothesis of faster healing for the sites augmented with autologous bone.
Histologic evaluation of a human immediately loaded titanium implant with a porous anodized surface.
BACKGROUND: Several researchers have demonstrated, in the past decade, in clinical and histologic studies, that immediate loading can be successfully used in implant dentistry. Many factors are thought to be of importance in obtaining mineralized tissues at the interface. One of these factors is the implant surface characteristics. Recently, an implant with a new porous anodized surface has been introduced in the market. PURPOSE: The goal of this study was to histologically evaluate a clinically retrieved immediately loaded implant with a porous anodized surface. MATERIALS AND METHODS: After a 6-month loading period, an immediately loaded implant with a porous anodized surface that had been inserted in the posterior maxilla was retrieved. RESULTS: Histology showed that mineralized tissue was present at the interface and the bone-implant contact percentage was about 60%. No gaps or fibrous tissue or inflammatory infiltrate were present at the interface. CONCLUSIONS: Results show that immediate loading of dental implants has no untoward effects on the formation of mineralized tissues at the interface. Immediate loading is a possible alternative in implant dentistry. key words: dental implants, histology, immediate loading, oxide coating, porous surface
Bone response to machined and resorbable blast material titanium implants: an experimental study in rabbits.
The aim of the present study was a comparison of implants' responses to a machined surface and to a surface sandblasted with hydroxyapatite (HA) particles (resorbable blast material [RBM]). Threaded machined and RBM, grade 3, commercially pure, titanium, screw-shaped inplants were used in this study. Twenty-four New Zealand white mature male rabbits were used. The inplants were inserted into the articular femoral knee joint according to a previously described technique. Each rabbit received 2 inplants, 1 test (RBM) and 1 control (machined). A total of 48 implants (24 control and 24 test) were inserted. The rabbits were anesthetized with intramuscular injections of fluanisone (0.7 mg/ kg body weight) and diazepam (1.5 mg/kg b.wt.), and local anesthesia was given using 1 mL of 2% lidocaine/adrenalin solution. Two rabbits died in the postoperative course. Four animals were euthanatized with an overdose of intravenous pentobarbital after 1, 2, 3, and 4 weeks; 6 rabbits were euthanatized after 8 weeks. A total of 44 implants were retrieved. The specimens were processed with the Precise 1 Automated System to obtain thin ground sections. A total of 3 slides were obtained for each implant. The slides were stained with acid and basic fuchsin and toluidine blue. The slides were observed in normal transmitted light under a Leitz Laborlux microscope, and histomorphometric analysis was performed. With the machined implants, it was possible to observe the presence of bone trabeculae near the implant surface at low magnification. At higher magnification many actively secreting alkaline phosphatasepositive (ALP+) osteoblasts were observed. In many areas, a not yet mineralized matrix was present. After 4 to 8 weeks, mature bone appeared in direct contact with the implant surface, but in many areas a not yet mineralized osteoid matrix was interposed between the mineralized bone and implant surface. In the RBM implants, many ALP+ osteoblasts were present and in direct contact with the implant surface. In other areas of the implant perimeter it was possible to observe the formation of an osteoid matrix directly on the implant surface. Mature bone with few marrow spaces was present after 4 to 8 weeks. Beginning in the third week, a statistically significant difference (P < .001) was found in the bone-implant contact percentages in machined and RBM implants. It must be stressed that these results have been obtained in a passive, nonloaded situation.
Bone regeneration with calcium sulfate: evidence for increased angiogenesis in rabbits.
Autologous bone is the preferred bone graft material because it carries proteins as bone-enhancing substrates, minerals, and vital bone cells. Calcium sulfate (CS) is a well-tolerated, biodegradable, osteoconductive bone graft substitute and is a reasonable alternative to autogenous bone graft. Blood vessels are an important component of bone formation and maintenance. The process of vascular induction is called angiogenesis, and it plays a key role in all regenerative processes. Bone tissue differentiation is related to the local presence of blood vessels. One method to evaluate the presence of blood vessels in a tissue is to count the microvessels to evaluate microvessel density (MVD). The aim of the present study was to conduct a comparative evaluation of microvessel density in sites treated with CS and autologous bone in rabbits, with or without e-PTFE nonresorbable membranes (Gore-Tex, Flagstaff, Ariz). Nine New Zealand rabbits, each weighing about 2.5 kg, were used in this experiment. Three 6-mm wide defects were created in each tibial metaphysis. The defects were filled in a random way. The defects of group 1 (3 rabbits) were filled with CS granules (Surgiplaster, Classimplant, Rome, Italy) and covered with e-PTFE membranes. The defects in group 2 (3 rabbits) were filled with CS granules (Surgiplaster). The defects in group 3 (3 rabbits) were filled with autologous bone. A total of 54 defects were filled (18 with CS and e-PTFE membranes, 18 with CS alone, and 18 with autologous bone). No postoperative deaths or complications occurred. All nine animals were sacrificed at 4 weeks. MVD results were as follows: in the first group, 9.88 +/- 4.613; in the second group, 7.92 +/- 1.998; and in the third group, 5.56 +/- 1.895. P = .000 was highly significant. Statistically significant differences were found between groups 1 and 3, 1 and 2, and 2 and 3. The presence of more blood vessels in the sites treated with CS could help to explain the good results reported in the literature with the use of CS.
Vertical distraction osteogenesis of fibular free flap in mandibular prosthetic rehabilitation: a case report.
A 17-year-old boy underwent three cycles of chemotherapy and a subsequent mandibular resection for a Ewing's sarcoma of the left body and ramus. The mandible was immediately reconstructed with a microvascular osteomuscular fibular flap. One year after the mandibular reconstruction, distraction osteogenesis of the anterior portion of the fibula was performed using a Martin distractor according to the Hoffmeister technique. Bone lengthening was achieved at a rate of 1 mm/day by turning the device twice each day for 12 days. Subsequently, we waited for 70 days for bone consolidation to occur. After 6 additional weeks, five Maestro implants were placed into the distracted fibula. Bone specimens were retrieved with a trephine bur during implant placement. Mature bone was present after 70 days and after 6 months. The bone height increase was 12 mm.
Identification of differentially expressed genes in human salivary gland tumors by DNA microarrays.
Differentially expressed genes among different benign and malignant salivary gland tumors were identified by use of cDNA microarrays containing 19,000 human expressed sequence tags. Tumors were classified by using a subset of 486 genes. Benign Warthin's tumor and pleomorphic adenoma showed very distinctive gene expression patterns. One hundred and thirty-three genes differentiated the single malignant clear cell carcinoma from non-tumor salivary glands (P < 0.01), whereas only 16 genes separated it from the highly related benign pleomorphic adenoma (P < 0.01). Fifty-seven cDNAs were associated with mucoepidermoid carcinoma (P < 0.01). The identified genes might help to disclose the molecular mechanisms and processes underlying malignant salivary gland tumors.
WNT-1 expression in basal cell carcinoma of head and neck. An immunohistochemical and confocal study with regard to the intracellular distribution of beta-catenin.
BACKGROUND: The WNT gene family is a group of developmental genes involved in cell growth regulation, differentiation and organogenesis in both vertebrates and invertebrates. These genes are also involved in oncogenesis: beta-catenin, a component of the WNT pathway, has been reported to be involved in the genesis of numerous human cancers. WNT-1 pathway signaling is mediated via interactions between beta-catenin, a multifunctional protein playing an important role in cell-to-cell adhesion and gene expression, and members of the LEF-1/TCF family of transcription factors. The WNT signal stabilizes beta-catenin protein and determines its accumulation in the cytoplasm and nucleus. MATERIALS AND METHODS: In order to evaluate the role of WNT-1 in the neoplastic progression of basal cell carcinoma (BCC), an immunohistochemical and confocal study of its expression and its correlation with beta-catenin distribution was performed in 46 selected cases of BCCs of the head and neck region. RESULTS: While normal skin showed a WNT-1-positive staining only of the cutaneous annexa and a few cells in the basal/parabasal layers, the areas of de-differentiated BCCs showed a high granular positive staining (50-80% of cells). On the other hand, normal skin was characterized by an intense membranous staining for beta-catenin, with a progressive displacement of the signal toward the periphery of the cells. In BCC the absence of membrane localization and cytosolic staining for beta-catenin were detected in de-differentiated cases. A significant correlation (by Pearson's analysis) between overexpression of WNT-1 and free pools of beta-catenins was observed in these tumors. CONCLUSION: According to these data, the potential role of the WNT-1 gene in BCC seems to correlate with its ability to induce elevated cytoplasmic beta-catenin levels, suggesting that the WNT-1 gene can activate an intracellular signaling pathway involved in the process of cell transformation.
Sandblasted and acid-etched dental implants: a histologic study in rats.
PURPOSE: Current literature has revealed that surface etching of endosseous implants can improve bone-implant contact. The aim of this study was to evaluate the differences in bone-implant contact (BIC) between sandblasted/acid-etched and machined-surface implants. MATERIALS AND METHODS: Thirty-two Sprague-Dawley rats were used in this study. Two implant surfaces, Ecotek (sandblasted/ acid-etched) and machined, were used with 1 implant placed in each tibia of the animals. A total of 64 implants were placed. BIC was evaluated at 5, 15, 30, and 60 days. Histomorphometry of the BIC was evaluated statistically. RESULTS: The sandblasted/acid-etched surface demonstrated a greater BIC percentage than the machined surface. This difference was statistically significant only at 30 and 60 days after healing. DISCUSSION AND CONCLUSION: The sandblasted/acid-etched surface demonstrated a stronger bone response than the machined one at a later period of healing.
Histologic evaluation of autogenous calvarial bone in maxillary onlay bone grafts: a report of 2 cases.
Bone augmentation for implant dentistry has become a necessary procedure for a number of edentulous patients. Calvarial bone grafting constitutes an important tool in achieving maxillary augmentation and sinus elevation. Much effort has been directed toward improving graft survival and volumetric maintenance. The purpose of the present study was to evaluate the histologic results of the calvarial onlay graft for maxillary reconstruction before implant placement. Two patients underwent maxillary augmentation using autogenous calvarial onlay grafts. After a 4-month healing period, biopsies of the augmented regions were performed and implants were placed. The implants were loaded after 5 months and then clinically examined after 15 months of function. Biopsies showed that calvarial onlay grafts were well incorporated into the preexisting bone after a 4-month period. Histologic and histomorphometric findings demonstrated a living bone that showed features characteristic of mature and compact osseous tissue. The restored Implants were stable and osseointegrated after a 15-month period of follow-up. The use of calvarial onlay grafts can be a predictable and successful method to achieve maxillary augmentation, allowing appropriate placement of implants and stable prosthetic restorations.
Immediate loading of dental implants placed in distracted bone: a case report.
A 40-year-old female patient presented for rehabilitation of an edentulous mandible with endosseous implants. Radiologic examination showed evidence of moderate atrophy in the intraforaminal area and an even more pronounced level of bone resorption in the posterior mandible. The patient desired a fixed rehabilitation with re-establishment of the posterior occlusal plane. From an esthetic standpoint, it was necessary to provide a restoration with crowns the same height as the original teeth while avoiding an unfavorable biomechanical situation. Vertical distraction of the complete mandible was performed using a Martin distractor according to the Hoffmeister technique. At the end of the period of activation and consolidation, the distractor was removed and 8 Frialit-2 Synchro-type implants were placed in predetermined sites and immediately loaded with a cemented transitional prosthesis. Ten months later the definitive restoration was delivered. The absence of any pathologic symptoms or negative radiologic findings 12 months after the surgery suggests a satisfactory result in the short term.
Comparative analysis study of 702 dental implants subjected to immediate functional loading and immediate nonfunctional loading to traditional healing periods with a follow-up of up to 24 months.
PURPOSE: The aim of this study was to clinically evaluate immediate functionally loaded (IFL) and immediate nonfunctionally loaded (INFL) implants for various indications compared to a control group with a conventional healing period. MATERIALS AND METHODS: Two hundred fifty-three patients took part in the study. A total of 702 XiVE implants (Dentsply/Friadent, Mannheim, Germany) were placed: 253 IFL implants, 135 INFL implants, and 314 controls. RESULTS: In each of the 3 groups, 2 implants failed. For all the other implants involved, from a clinical and radiographic point of view, osseointegration was successful. DISCUSSION: As long as the prerequisites are fulfilled, immediate functional loading and immediate nonfunctional loading are predictable techniques, not only in completely edentulous patients but also in partially edentulous patients. CONCLUSION: Immediate functional loading and immediate nonfunctional loading appear to be techniques that can provide satisfactory implant success rates in selected cases.
Clinical outcome of 802 immediately loaded 2-stage submerged implants with a new grit-blasted and acid-etched surface: 12-month follow-up.
PURPOSE: The aim of this study was to evaluate the clinical outcome of delayed or immediately loaded implants of 3 different implant macrodesigns. The hypothesis was that no significant differences in implant success would be observed between immediately and delayed loaded implants. MATERIALS AND METHODS: Between July 2003 and December 2003, 321 patients were consecutively enrolled for this study. Immediate loading was performed in cases where the implant stability quotient (ISQ) values were > 60 (as determined by resonance frequency analysis) and implant insertion torque was > 25 Ncm. In the case of delayed loading, a submerged technique (2-stage) or a single-stage procedure was used. The following variables were statistically analyzed with logistic regression: implant length, implant diameter, implant type, implant site, insertion torque, ISQ, and type of loading (immediate or delayed). RESULTS: Eight hundred two implants were placed. Immediate loading was chosen for 423 implants and delayed loading for 379 implants. All implants were followed up for a minimum of 12 months after prosthetic loading. Only 3 implants were lost, with an overall success rate of 99.6%. No statistically significant differences were found for any variables between the failures in the 2 groups (immediate loading protocol versus delayed loading). Implants with a crestal bone loss greater than 0.2 mm during the first year of observation (69 cases) were evaluated as a group; within this subset, only ISQ value (P < .004), implant length (P < .002), and implant type (P < .049) had a statistically significant effect on crestal bone resorption. CONCLUSIONS: Based upon this study of 802 implants, no significant differences in implant success were observed between the 2 groups.