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Biomedical subjects

Adriano Piattelli

Publications and source records attributed to Adriano Piattelli.

At least 55 records · Page 3Linked to original sources
PubMed2005

p63 overexpression associates with poor prognosis in head and neck squamous cell carcinoma.

p63 belongs to a protein family that includes 2 structurally related proteins, p53 and p73. The aim of this study was to investigate the biologic role of p63 in oral tumorigenesis and its possible role as prognostic marker in oral cancer. Ninety-four cases of oral squamous cell carcinoma and 10 cases of normal mucosa were analyzed for p63 expression by immunohistochemistry. Normal oral mucosa showed a basal and parabasal expression of p63. Five (5.3%) cases of oral cancer showed less than 10% of positive tumor cells; in 33 (35.1%) cases the positive tumor cells comprised between 10% and less than 30%, in 36 (38.3%) cases the positive tumor cells comprised between 30% and less than 50%, and in 20 (21.3%) cases the positive tumor cells were more than 50%. There was also a statistically significant correlation between p63 expression and tumor differentiation: p63 expression was amplified in poorly differentiated tumors (P < .05). When analyzed for prognostic significance, patients with perineural infiltration had poorer survival rates than the group with no perineural infiltration (P < .05) and patients with increased p63 expression had poorer survival rates than the group with reduced p63 expression (P < .05). The statistical analysis showed no significant correlation between p63 expression, sex, age, tumor size, staging, recurrence, and metastasis. Cases with diffuse p63 expression were more aggressive and poorly differentiated and related to a poorer prognosis. These data suggest that p63 expression may be useful to identify cases of oral squamous cell carcinoma with more aggressive and invasive phenotype providing novel diagnostic and prognostic information on individual patient survival with oral cancers.

Adolescent↗
PubMed2005

Genetic portrait of mild and severe lingual dysplasia.

Squamous cell carcinoma is the most frequent malignant tumor of the oral cavity and often arises from premalignant lesions. Traditional methods used by the pathologist are subjective and lack the sensitivity to predict accurately which precancers may progress with time. Therefore, it is important to search for markers that may identify progression of premalignant lesions. Microarray technology can be use with this aim. Here, we define the genetic expression profile of lingual dysplasia (DS) progression. By using cDNA microarray containing 19.2K clones and a baseline of 11 normal tissues, we compared 5 mild and 4 severe DS. We identified 270 genes differentially expressed in normal tissue vs. mild DS (i.e. 161 up- and 109 down-regulated) and 181 genes differentially expressed in mild vs. severe DS (i.e. 63 up- and 118 down-regulated). The described genes cover a broad range of functional activities: (a) anti-oxidative, (b) DNA-repair, (c) inflammatory response, (d) cell-adhesion/mobility, (e) extracellular matrix depolymerization, and (f) cell-cycle regulation. The data reported better define DS progression and can help in classifying premalignant lesions.

Adult↗
PubMed2005

An in vitro model for dissecting distraction osteogenesis.

Distraction osteogenesis (DO) is a mechanotransduction process capable of generating viable osseous tissue by the gradual separation of osteotomized bone edges. Several variables are implicated in DO: magnitude of mechanical strain, distraction rate, and type of distracted bone. The combination of these factors acts on different types of cells inducing apoptosis, cell proliferation, and differentiation. The elucidation of the molecular mechanisms has important clinical implications because it may facilitate the use of recombinant proteins or gene therapy to accelerate bone regeneration. Previous reports have analyzed several molecules such as extracellular matrix proteins, cytokines, bone morphogenetic proteins, hormones, and angiogenic factors. Moreover, a single protein can have multifunctional roles. With such a huge number of mechanical, histologic, cellular, and molecular variables, there is the need to have a cell culture model that enables the selection of the effect of a specific strength to a single cell type at different time points and with or without cytokines. The analysis of the genetic profiling of a cell line cultured on an equibiaxial stretch device has such characteristic. Because there is a recruitment and commitment of preosteoblastic cells during bone lengthening and no previous report has focus on them, the authors used a preosteoblast MC3T3-E1 cell line to detect the early molecular effects of distraction on mesenchymal cells. By using DNA microarrays containing 15,000 clones, the authors identified several genes the expression of which was significantly up- or down-regulated. The differentially expressed genes cover a broad range of biological processes: cell growth, metabolism, morphogenesis, cell communication, response to stress, and cell death. The data reported are the first genetic portrait of stretched preosteoblasts. They can be relevant in the better understanding of the molecular mechanism of DO and as a model for comparing the effect of distraction on different cell lines and primary cultures, rate and strength of distraction, and with or without cytokines.

3T3 Cells↗
PubMed2005

Maxillary sinus augmentation using a synthetic cell-binding peptide: a histologic and transmission electron microscopy case study in man.

PepGen P-15 is a combination natural anorganic bovine-derived hydroxyapatite matrix coupled with a synthetic cell-binding peptide (P-15). This material has improved bone formation in periodontal osseous defects and bone regenerative procedures. There were 3 specimens retrieved 18 months after a sinus lifting procedure using PepGen P-15. These specimens were treated to be observed under light microscopy and transmission electron microscopy. Light microscopy showed that most of the particles were surrounded by newly formed bone. In some areas, osteoid matrix was present. No acute inflammatory infiltrate was present. In transmission electron microscopy, all phases of bone formation (i.e., osteoid matrix, woven bone, and lamellar bone) were observed in the newly formed bone around the biomaterial particles. In some regions, this newly formed bone seemed to present interdigitations connecting to or entering into the particle surface. To our knowledge, this is the first report presenting data on transmission electron microscopy of PepGen P-15 used in a sinus augmentation procedure in man. Our results confirm previous reports on the clinical effectiveness of this material.

Alveolar Ridge Augmentation↗
PubMed2005

Genetic profiling of central giant cell granuloma of the jaws.

Central giant cell granuloma (CGCG) of the jaws is a central osteolytic lesion characterized histologically by multinucleated giant cells in a background of ovoid to spindle-shaped mesenchymal cells. Whether CGCG is a reactive lesion or a truly benign neoplasm remains undetermined, and the mechanism determining the onset of the disease remains unknown. To have more information regarding the genetic events involved in CGCG, the authors decided to perform an expression profile. Samples were derived from two surgically resected CGCG of the mandible. RNA extracted from a pool of three normal bone tissues was used as control. By using DNA microarrays containing 19,200 genes, the authors identified several genes whose expression was significantly up- or down-regulated. The differentially expressed genes cover a broad range of functional activities: cell cycle regulation; signal transduction; and vesicular transport. It was also possible to detect some genes whose function is unknown. The authors believe the data reported to be the first genetic portrait of CGCG of the jaws. Several markers have been identified that can potentially help in identifying some biological behavior (ie, quiescent versus aggressive lesions), as well as genes whose products could be potentially disease-specific targets for therapy. However, the authors think that more cases are needed, especially those comparing quiescent and aggressive lesions, before the exact profile of CGCG is known.

Gene Expression↗
PubMed2005

Haemangiopericytoma of the maxillary gingiva: report of a case.

AIM: Haemangiopericytoma (HPC) represents approximately 3% of all tumours in the head and neck. This tumour is a soft tissue tumour derived from mesenchymal cells with pericytic differentiation. We present the clinicopathological findings of a case. MATERIALS AND METHODS: A 69-year-old man was referred to our Department for a mass located on the right pre-molar maxillary gingiva; this mass caused problems during chewing, but was otherwise asymptomatic. RESULTS: Clinical examination revealed a nodular, pink lesion, 3.5 cm in diameter, which was lined with normal mucosa. The lesion was mobile in relation to the deep and superficial tissues. Microscopic analysis of the neoplasm showed a vascular rich pattern, constituted by vessels covered with flat endothelium and surrounded by abundant spindly cells. On the basis of these histological and immunohistochemical findings, the final diagnosis was HPC. CONCLUSIONS: HPC is an uncommon vascular tumour for which the biological behaviour is difficult to predict. In our patient, no recurrences or distant metastases were present at a 4 years follow-up.

Aged↗
PubMed2005

Alveolar ridge augmentation: a comparative longitudinal study between calvaria and iliac crest bone grafrs.

Insertion of endosseous implants is often difficult because of lack of supporting bone. In the case of severe atrophy of the jaws, a large volume of autogenous bone can be harvested from the iliac crest and calvaria. Both grafts undergo partial resorption with time, but the rate of bone loss has not been fully elucidated. The aim of this study was to evaluate the alveolar bone height gain (ABHG) obtained with iliac crest and calvaria bone grafts. Twenty-five patients had mandibular bone grafts, 32 had maxillary bone grafts, and 11 had both mandibular and maxillary bone grafts. Measures were made on preoperative, postoperative, and follow-up radiographs. A general linear model was used to evaluate the rate of ABHG plotted against months elapsed from the time of the operation to the time of follow-up. General linear model output showed a statistically significant effect for only the type of donor bone graft (P =.004), with a better ABHG for calvaria. The iliac crest bone grafts lost most of the ABHG in the first 6 months, whereas calvaria bone grafts lost ABHG over a greater interval of time. The type of bone graft is the strongest predictor of ABHG, and calvaria bone graft had a higher stability than did iliac bone graft. However, the gap in ABHG between the 2 grafts tended to decrease over time.

Adult↗
PubMed2005

Bone remodeling in immediately loaded and unloaded titanium dental implants: a histologic and histomorphometric study in humans.

Remodeling is thought to prevent microdamage accumulation caused by repetitive loading and to increase the fatigue life of bone. The bone remodeling rate (BRR) is the period of time needed for new bone to replace the existing bone and to allow for the adaptation of bone to its environment. BRR is expressed as a percentage or volume of new bone within a specific time period. The aim of the present study was to evaluate bone remodeling events on submerged and immediately loaded dental implants. Twelve patients with edentulous mandibles participated in this study. All patients were rehabilitated with fixed mandibular prostheses, with 10 dental implants per patient. An additional implant was inserted in the most distal posterior mandibular jaw region. In 6 patients, these additional implants were loaded with a fixed provisional prosthesis the same day of the implant surgery and loaded. In the other 6 patients, the additional implants were left submerged and not loaded. After 6 months, all the additional implants were retrieved with a trephine. The percentage of woven and lamellar bone, number of osteoclasts and osteoblasts, and percentage of bone labeled by tetracycline at 0.5 mm and 2 mm from the implant surface were evaluated. The percentage of lamellar bone, number of osteoblasts, and percentage of bone tetracycline labeling was significantly higher in the loaded implants than in the unloaded implants (P =.0001). Also in the loaded implants, the percentage of woven and lamellar bone, number of osteoclasts and osteoblasts, and percentage of bone tetracycline labeling was significantly higher at 0.5 mm than at 2 mm from the implant surface (P =.0001). No such differences were found in unloaded implants (P =.377). In conclusion, we found that (1) loading appeared to stimulate bone remodeling at the interface, (2) a higher percentage of lamellar bone was found in loaded implants, (3) the percentage of bone labeling was higher at the interface of loaded implants, (4) no differences were found in the BRRs between immediately loaded and unloaded implants, and (5) immediate loading had not interfered on the lamellar bone formation at the interface and had not produced formation of woven bone at the interface.

Adult↗
PubMed2005

7-year follow-up of 93 immediately loaded titanium dental implants.

Recently, several experimental and clinical investigations found that immediately loaded implants obtained satisfactory levels of osseointegration with high success percentages. Only a few long-term studies of immediately loaded implants have been reported in the literature. The aim of this study was a 7-year clinical and radiographic follow-up of 93 immediately loaded dental implants in human patients. Eleven patients were consecutively enrolled in this study. A total of 7 full and 9 partial edentulous arches were rehabilitated. Patients presented a completely edentulous mandible (n=6), a completely edentulous maxilla (n=1), mandibular posterior edentulous areas (n=5), or a posterior maxillary edentulous area (n=1). Patients were rehabilitated with a bar and an overdenture (n=4), a provisional prosthesis of 3 to 12 elements (n=11), or a metal-ceramic bridge of 10 elements (n=1). A total of 93 implants were inserted and loaded within a 24-hour time frame. Six implants failed in the first year after loading. No more failures were observed in the following 6 years, and all the other implants were well integrated from a clinical and radiographic point of view. The cumulative success rate at 7 years was 93.5%, and the prostheses survival rate was 98.5%. The mean marginal bone loss was 0.6 mm after the first year and 1.1 mm at the 7-year evaluation. Primary stability is one of the most important parameters in immediately loaded implants because it avoids micromotion at the bone-implant interface. Four of the 6 failures in our patients occurred in partially edentulous patients; an excessive load applied to these small bridges could be the reason for the failure. Also, the bone quality is important, for 3 of our failed implants had been inserted in D3 bone. Our clinical and radiographic results have shown that these immediately loaded implants have remained osseointegrated for a long period. Our results point to the possibility of using the immediate loading technique in selected and well-informed cases.

Adult↗
PubMed2005

Bone response to submerged, unloaded implants inserted in poor bone sites: a histological and histomorphometrical study of 8 titanium implants retrieved from man.

An important parameter that influences the long-term success of oral implants is the bone quality of the implant bed. Posterior areas of the jaws have been avoided in implant dentistry because of their poor bone quality, higher chewing forces, and presumed higher implant failure rates. Several researchers have deemed soft bone implant sites to be a great potential risk situation, and most failures have been found in sites where the bone density was already low. The inferior success rates in the posterior maxilla have been attributed to a lower bone density and a lesser bone-implant interface. The aim of the present study was a histological and histomorphometrical analysis of the bone response to submerged implants inserted in posterior areas of the human jaws and retrieved, for different causes, after healing periods varying from 6 weeks to 12 months. Eight submerged implants that had been retrieved for different causes after different healing periods were evaluated in the present study. All implants were submerged and unloaded. Three implants had been removed for inadequate patient adaptation, 2 for inability of the implant to meet changed prosthetic needs, 1 for not optimal position from esthetic and hygiene aspects, and the last 2 for pain and dysesthesia. All the implants were retrieved with a 5-mm trephine bur. Newly formed peri-implant bone was found in all implants even after shorter healing periods. The bone-implant contact percentage varied from 30% to 96%. In conclusion, some surfaces have an improved characteristic of contact osteogenesis in soft bone, with coverage of the implant surface with a bone layer as a base for intensive bone formation and remodeling. We documented osseointegration of implants with a rough surface even after an insertion period of less than 2 months, both in the mandible and in the maxilla. From these results, we tentatively extrapolate that these implants might be carefully loaded after 2 months of healing, even when inserted in soft bone. A higher removal torque value might lead to a more predictable use of shorter implants, to a support of a prosthesis with fewer implants, or to shorter healing periods.

Alveolar Bone Loss↗
PubMed2005

Screw- vs cement-implant-retained restorations: an experimental study in the Beagle. Part 1. Screw and abutment loosening.

The causes of implant failures can be biological or mechanical. The mechanical causes include fracture of the implant, fracture of the abutment, and loosening of the abutment. Numerous studies show that abutment loosening constitutes one of the marked implant postsurgery complications requiring clinical intervention. The aim of the present study was to evaluate the incidence of the screw loosening in screwed or cemented abutments. Six adult male Beagles were used. In each dog, the first molars and 2 premolars were extracted. The sutures were removed after 7 days. After 3 months, 10 implants were placed in each dog, 5 in the right mandible and 5 in the left mandible. The abutments either were screwed in (n=30) by applying a total strength of 30 N/cm or were cemented (n=30). After 12 months, 8 (27%) loosened screws were present in screwed abutments, whereas no abutment loosening was observed in cemented abutments (P = .0001). Screwed abutments are often submitted to nonaxial loads that determine screw and abutment loosening.

Animals↗
PubMed2005

Histologic analysis of an immediately loaded implant retrieved after 2 months.

Human biopsy of immediately loaded implants is the most important way to determine the occurrence of osseointegration. Implants inserted in sites with poor bone quality have been associated with lower success rates. The aim of this study is to document the early healing processes in a man around an immediately loaded implant retrieved after a 2-month loading period. An implant was inserted in the mandible of a 32-year-old patient and was loaded into a nonfunctional loading mode with a fixed provisional prosthesis the same day of the implant surgery. After 2 months, because the patient had difficulty accepting the implant, the implant was retrieved with a 5-mm trephine drill. Before retrieval, the implant appeared to be clinically osseointegrated, and no mobility was present. The preexisting bone quality was type D4. The implant was surrounded by newly formed bone lamellae with a width of 200 to 400 microm. In many areas it was possible to observe osteoblasts producing osteoid matrix directly on the implant surface. Bone-to-implant contact percentage was 71% +/- 3.2%. Even in a poor bone site and after a healing period of only 2 months, we observed a high bone-to-implant contact percentage. We can confirm that immediately loaded implants placed in soft spongy bone after a 2-month healing period can present mineralized tissue at the interface.

Adult↗
PubMed2005

A 16-year study of the microgap between 272 human titanium implants and their abutments.

A microgap has been described at the level of the implant-abutment connection. This microgap can be colonized by bacteria, and this fact could have relevance on the remodeling of the peri-implant crestal bone and on the long-term health of the peri-implant tissues. The authors report on 272 implants with screw- or cement-retained abutments retrieved from humans for different causes during a 16-year period. In the implants with screw-retained abutments, a 60-microm microgap was present at the level of implant-abutment connection. In some areas the titanium had sheared off from the surface and from the internal threads. The contact between the threads of the implant and those of the abutment was limited to a few areas. Bacteria were often present in the microgaps between implant and abutment and in the internal portion of the implants. In implants with cement-retained abutments, a 40-microm microgap was found at the level of the implant-abutment connection. No mechanical damage was observed at the level of the implant or of the abutment. All the internal voids were always completely filled by the cement. No bacteria were observed in the internal portion of the implants or at the level of the microgap. The differences in the size of the microgap between the two groups were statistically significant (P < .05). In conclusion, in screw-retained abutments the microgap can be a critical factor for colonization of bacteria, whereas in cement-retained abutments all the internal spaces were filled by cement. In these retrieved implants, the size of the microgap was markedly variable and much larger than that observed in vitro.

Bacteria↗
PubMed2005

Histologic and histomorphometric analysis of an immediately loaded implant retrieved from man after 14 months of loading.

OBJECTIVE: The aim of this study was a histologic and histomorphometric analysis of the peri-implant tissue reactions and the bone/titanium interface in an immediately loaded titanium implant inserted in a soft bone site and retrieved, in man, after a 14-month loading period. METHODS. A 65-year-old patient presented with a partial edentulism in the left posterior mandible. The patient was rehabilitated with three dental implants inserted in the left first, second, and third molar sites. All these implants were immediately put into a nonfunctional loading mode and joined with the other implants that supported the temporary restorations. After 14 months, the most distal implant and surrounding tissues were retrieved because of psychological problems of the patient. RESULTS: Newly formed, strongly stained, compact, mature cortical bone with few marrow spaces was observed around the implant, especially in the coronal portion. No inflammatory infiltrate was present around the implant. No gaps or dense fibrous connective tissue were found at the bone/metal interface. No apical epithelial migration was found. In the cortical portion, bone remodeling areas were present with many newly formed Haversian canals. Only in a few areas of the interface was it possible to observe an osteoblast rim. In the apical portion, newly formed bone trabeculae were present; these were composed mostly by woven bone, and only a small quantity of preexisting lamellar bone was present. Histomorphometric evaluation showed that the bone/implant contact percentage was 72.6% (+/-2.7%). CONCLUSIONS: We found that, in immediately loaded implants inserted in soft tissue sites, it was possible to find a high percentage of bone-to-implant contact and that osseointegration was maintained for more than 1 year. This fact could be partly explained with the use of an implant with a rough surface.

Aged↗
PubMed2005

Collagen fiber orientation in human peri-implant bone around immediately loaded and unloaded titanium dental implants.

BACKGROUND: The main factor in determining the mechanical properties of bone is the collagen configuration. METHODS: This study investigated the birefringence in human bone around loaded and unloaded titanium dental implants to evaluate the collagen fiber orientation using circularly polarized light (CPL) and scanning electron microscopy (SEM). A total of 10 titanium dental implants, five immediately loaded and five unloaded, were used. The birefringence measurements were performed on digitized images of both loaded and unloaded implants. All images detected at 50x were measured using a software image analysis. RESULTS: In the bone around loaded implants, the transverse collagen fiber area was 45,481+/-3,037 pixel2 (mean+/-SD), while the area of longitudinal collagen fibers was 13,676+/-2,232 pixel2 (mean+/-SD). In the unloaded implants, the transverse collagen fiber area was 32,174+/-2,554 pixel2 (mean+/-SD), while the area of longitudinal collagen fibers was 89,073+/-1,960 pixel2 (mean+/-SD). The CPL measurements of the birefringence for transverse collagen fibers of loaded versus unloaded implants indicated that the differences were statistically significant (P <0.05). The results for the longitudinal collagen fibers of loaded versus unloaded implants were also statistically significant (P <0.05). CONCLUSIONS: In the bone around loaded dental implants, transverse collagen fibers were more abundant, while in the unloaded implants, collagen fibers run more longitudinally. The load seemed to determine the collagen fiber orientation.

Biocompatible Materials↗
PubMed2005

Histologic and histomorphometric findings from retrieved, immediately occlusally loaded implants in humans.

BACKGROUND: The immediate loading treatment concept can be successfully used in implant dentistry. Bone cells migrate onto the implant surface and establish a stable anchorage on the titanium surface. When implants are loaded immediately after surgery, there is a high long-term success rate of the implant-supported reconstruction. Based on histologic observations from different animal studies, the interface of immediately loaded implants can have a direct bone-to-implant connection without any fibrous tissue formation. Mature bone formation is dependent on the loading period. The aim of this study was to demonstrate a histologic analysis of retrieved, clinically stable immediately loaded implants with different implant designs and surfaces. An objective demonstration of the bone-implant interface was presented for the implant systems used. METHODS: A total of 29 implants with different implant designs and surfaces were retrieved from patients who were treated with implants using an immediate loading protocol and fixed immediate restorations placed the same day after surgery. The loading period was between 2 and 10 months. The bone-implant interface was examined histologically and histomorphometrically. RESULTS: A high bone-to-implant percentage of 66.8% (+/-8.9%) was found in the examined retrieved implants. Some marginal bone resorption was observed in the crestal part of the implants. CONCLUSION: According to the present histologic and histomorphometric evaluation of retrieved, clinically stable implants, immediate occlusal loading can present a high level of bone-to-implant contact in humans.

Alveolar Process↗
PubMed2005

Immediate functional loading of edentulous maxilla: a 5-year retrospective study of 388 titanium implants.

BACKGROUND: Immediate functional loading is a new surgical-prosthetic technique that can be used extensively in implant placement. Because of a lack of experimental reports regarding edentulous maxilla, we decided to evaluate the survival rate of immediately loaded dental implants in this area. METHODS: Forty-three patients (44.4% male) with a median age of 55 years receiving 388 implants (mean 9.0 per case) were enrolled in this study. Cross-arch acrylic provisional restorations were performed in the same stage. Data were analyzed by Kaplan-Meier product limit estimation. Stratification of implants survival was performed for the available variables of interest, and comparisons were analyzed by a log rank test. Cox algorithm was used for multivariable analysis. RESULTS: At 5-year follow-up, the crude survival rate (overall survival not stratified according to any available variable) was 98%. All failures occurred within 6 months from loading. We found differences in survival relating to: 1) implant diameter (99.37% for diameter < or =5.25 mm and 93.75% for diameter >5.25 mm); 2) number of implants (99.29% for < or =10 implants and 96.30% for >10); and 3) gender (97.08% and 99.54% for males and females, respectively). Cox regression analysis showed that diameter of implants adjusted for patient age and gender was associated to an average risk of failure (hazard rate) of 3.13 (P value = 0.042, 95% confidence interval 1.04 to 9.43) per mm (from 3 to 6.5). CONCLUSIONS: Immediate functional loading is a reliable surgical-prosthetic procedure in edentulous maxillae. Implants with wider diameter are associated with a higher risk of failure.

Adult↗