PubMed Health⌕ Search

Biomedical subjects

Adriano Piattelli

Publications and source records attributed to Adriano Piattelli.

At least 91 records · Page 5Linked to original sources
PubMed2004

Osseointegration in a sinus augmented with bovine porous bone mineral: histological results in an implant retrieved 4 years after insertion. A case report.

BACKGROUND: A subject of controversy in implant dentistry is what is the most appropriate material for sinus augmentation. Little is known about the healing pattern and the osseointegration processes at the interface of implants placed in different grafting materials in man. Bovine porous bone mineral (BPBM) is a xenogenic material similar to human cancellous bone with a high biocompatibility and osteoconductivity. METHODS: A 50-year-old patient presented a posterior left maxilla with an insufficient bone height for implant insertion. In January 1999, a sinus lifting procedure was performed and the left sinus was augmented with BPBM; in November 1999, three implants were inserted, and in July 2000 a fixed prosthetic restoration was positioned. In June 2003 the connecting screw of the middle implant fractured and it was decided to remove the implant using a 5 mm trephine bur. RESULTS: All BPBM particles were surrounded by newly formed bone. No BPBM particle was in direct contact with the implant surface, and between the implant surface and the particles there was newly-formed bone. BPBM seemed to undergo a very slow resorption; the particles constituted 36% +/- 3% of the peri-implant tissues. The bone-implant contact percentage was 72% +/- 4%. CONCLUSIONS: In our specimens, we found an intimate, direct contact between bone and implant without an interposition of the graft material particles. A very high bone-to-implant contact percentage was present. Our results show that the slow resorption of the graft particles did not jeopardize the osseointegration of the implant.

Animals↗
PubMed2003

Suppression of the functionally coupled cyclooxygenase-2/prostaglandin E synthase as a basis of simvastatin-dependent plaque stabilization in humans.

BACKGROUND: The clinical benefits of statins are attributed to changes in plaque composition that lead to reduced metalloproteinase (MMP) activity and plaque stabilization. However, the molecular mechanism of this effect is unclear. Recently, we demonstrated enhanced expression of isoforms of inducible cyclooxygenase (COX) and PGE synthase (COX-2/mPGES) in human symptomatic plaque and provided evidence that this is associated with MMP-induced plaque rupture. The aim of this study was to characterize the effect of simvastatin on inflammatory infiltration and the expression of COX-2/mPGES and MMPs in human carotid plaques. METHODS AND RESULTS: Seventy patients with symptomatic carotid artery stenosis were randomized to the American Heart Association Step 1 diet plus simvastatin (40 mg/d) or the American Heart Association Step 1 diet alone for 4 months before endarterectomy. Plaques were subjected to analysis of COX-1, COX-2, mPGES, MMP-2 and MMP-9, lipid and oxidized LDL (oxLDL) content, and collagen content by immunocytochemistry, Western blot, and reverse transcription-polymerase chain reaction, whereas zymography was used to detect MMP activity. Immunocytochemistry was also used to identify CD68+ macrophages, CD3+ T-lymphocytes, smooth muscle cells (SMCs), and HLA-DR+ inflammatory cells. Plaques from the simvastatin group had fewer (P<0.0001) macrophages, T-lymphocytes, and HLA-DR+ cells; less (P<0.0001) immunoreactivity for COX-2/mPGES and MMPs; reduced (P<0.0001) gelatinolytic activity; increased (P<0.0001) collagen content; and reduced (P<0.0001) lipid and oxLDL content. Interestingly, COX-2/mPGES inhibition by simvastatin was completely reversed by mevalonate in vitro. CONCLUSIONS: This study demonstrates that simvastatin decreases inflammation and inhibits COX-2/mPGES expression in plaque macrophages, and this effect in turn may contribute to plaque stabilization by inhibition of MMP-induced plaque rupture.

Aged↗
PubMed2003

Residual aluminum oxide on the surface of titanium implants has no effect on osseointegration.

The cleanliness of titanium dental implants surfaces is considered to be an important requirement for achieving osseointegration, and it has been hypothesized that the presence of inorganic contaminants could lead to lack of clinical success. Aluminum ions are suspected to impair bone formation by a possible competitive action to calcium. The objective of the present study was to describe the effects of residual aluminum oxide particles on the implant surface on the integration of titanium dental implants as compared to decontaminated implants in a rabbit experimental model. Threaded screw-shaped machined grade 3 c.p. titanium dental implants, produced with high-precision equipment, were used in this study. The implants were sandblasted with 100-120 microm Al2O3 particles at a 5atm pressure for 1min, then 24 implants (control implants) underwent ASTM F 86-68 decontamination process in an ultrasonic bath. The other 24 implants (test implants) were washed in saline solution for 15min. Both test and control implants were air-dried and sterilized at 120 degrees C for 30min. After sterilization the implants were inserted into the tibiae (two test and two control implants in each rabbit). Twelve New Zealand white mature male rabbits were used in this study. The protocol of the study was approved by the Ethical Committee of our University. No complications or deaths occurred in the postoperative period. All animals were euthanized, with an overdose of intravenous pentobarbital, after 4 weeks. A total of 48 implants were retrieved. The images were analyzed for quantitation of percentage of surface covered by inorganic particles, bone-implant contact, multinucleated cells or osteoclasts in contact with the implant surface and multinucleated cells or osteoclasts found 3mm from the implant surface. The differences in the percentages between the two groups have been evaluated with the analysis of variance. The implant surface covered by inorganic particles on test implants was significantly higher than that of control implants (p=0.0000). No statistically significant differences were found in the bone-implant contact percentages of test and control implants (p=0.377). No statistically significant differences were found in the number of multinucleated cells and osteoclasts in contact with the implant surface (p=0.304), and at a distance of 3mm from the implant surface (p=0.362). In conclusion, our histological results do not provide evidence to support the hypothesis that residual aluminum oxide particles on the implant surface could affect the osseointegration of titanium dental implants.

Aluminum Oxide↗
PubMed2003

Central granular cell odontogenic tumour: report of the first malignant case and review of the literature.

Granular cell odontogenic tumours (GCOT) are rare neoplasms that usually manifest a benign clinical behaviour. We document the first case of GCOT exhibiting clinico-pathological features of malignancy that occurred in the maxilla of a 40-year-old male. The lesion appeared as an intra-oral polypoid mass and, at CT scan, as a poorly demarcated radiolucency eroding the cortical plate. Histologically, the tumour consisted of clusters of granular cells, exhibiting nuclear pleomorphism, prominent nucleoli and mitotic figures, and spindle cells in a collagenous stroma containing cementicles and strands of odontogenic epithelium. Morphologic transition from fibroblast-like to granular cells was frequently detected. The tumour cells extensively invaded the oral and respiratory mucosae and the adjacent soft tissues and exhibited vimentin and CD 68 immunoreactivity and high (21%) Ki 67 immunolabeling but not cytokeratins, E.M.A. actin, desmin, myosin or S-100 protein positivity. The patient experienced tumour recurrence 16 months after radical surgery. While the histogenesis of GCOT remains to be clarified, we document the existence of a malignant counterpart of this tumour and propose the name of malignant GCOT or granular cell odontogenic sarcoma for such entity.

Adult↗
PubMed2003

Ridge preservation following tooth extraction using a polylactide and polyglycolide sponge as space filler: a clinical and histological study in humans.

BACKGROUND: The placement of different graft materials and/or the use of occlusive membranes to cover the extraction socket entrance are techniques aimed at preserving/reducing alveolar ridge resorption. The use of grafting materials in fresh extraction sockets has, however, been questioned because particles of the grafted material have been found in alveolar sockets 6-9 months following their insertion. AIM: The aims of the study were to (i). evaluate whether alveolar ridge resorption following tooth extraction could be prevented or reduced by the application of a bioabsorbable polylactide-polyglycolide sponge used as a space filler, compared to natural healing by clot formation, and (ii). evaluate histologically the amount and quality of bone tissue formed in the sockets, 6 months after the use of the bioabsorbable material. MATERIAL AND METHODS: Thirty-six patients, undergoing periodontal therapy, participated in this study. All patients were scheduled for extraction of one or more compromised teeth. Following elevation of full-thickness flaps and extraction of teeth, measurements were taken to evaluate the distance between three landmarks (mesio-buccal, mid-buccal, disto-buccal) on individually prefabricated stents, and the alveolar crest. Twenty-six alveolar sockets (test) were filled with a bioabsorbable polylactide-polyglycolide acid sponge (Fisiograft), while 13 sockets (controls) were allowed to heal without any filling material. The flaps were sutured with no attempt to achieve primary closure of the surgical wound. Re-entry for implant surgery was performed 6 months following the extractions. Thirteen biopsies (10 test and three control sites) were harvested from the sites scheduled for implant placement. RESULTS: The clinical measurements at 6 months revealed, in the mesial-buccal site, a loss of bone height of 0.2 mm (1.4 SD) in the test and 0.6 mm (1.1 SD) in the controls; in the mid-buccal portion a gain of 1.3 mm (1.9 SD) in the test and a loss of 0.8 mm (1.6 SD) in the controls; and in the distal portion a loss of 0.1 mm (1.1 SD) in the test and of 0.8 (1.5 SD) mm in the controls. The biopsies harvested from the test sites revealed that the new bone formed at 6 months was mineralized, mature and well structured. Particles of the grafted material could not be identified in any of the 10 test biopsies. The bone formed in the control sites was also mature and well structured. CONCLUSION: The results of this study indicate that alveolar bone resorption following tooth extraction may be prevented or reduced by the use of a bioabsorbable synthetic sponge of polylactide-polyglycolide acid. The quality of bone formed seemed to be optimal for dental implant insertion.

Adult↗
PubMed2003

Cyclic guanosine monophosphate phosphodiesterase activity in human gingival carcinoma.

BACKGROUND: Cyclic guanosine monophosphate (cGMP) is an essential second messenger metabolized by phosphodiesterases (PDEs). OBJECTIVES: We looked for a possible correlation of PDE activities in human oral squamous cell carcinoma (OSCC) with and without lymph node metastases. MATERIALS AND METHODS: The analysis of phosphodiesterase activity and the cGMP assay were done by reverse-phase HPLC on samples of fresh or frozen gingival tissues. Analysis of cGMP was confirmed with the enzyme-linked immunoabsorption assay. RESULTS AND CONCLUSIONS: cGMP PDE activity was 34.92 +/- 7.17 SD, 12.89 +/- 4.43 SD, and 35.88 +/- 8.76 SD (nmols/mg of protein), respectively, in controls, samples without lymph node involvement (N-), and specimens with lymph node metastases (N+). cGMP values were 1.97 +/- 0.63 SD, 3.30 +/- 1.47 SD, and 3.49 +/- 1.47 SD (nmols/mg of protein). Our data support the hypothesis of a role for cGMP and PDE in the progression of OSCC.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2003

Healing of transplanted composite bone grafts-implants: a pilot animal study.

This experimental pilot study was undertaken to evaluate healing of titanium implants transplanted with the surrounding bone into recipient osseous sites in the rabbit mandible. One short implant was inserted in the horizontal portion of the mandible in each of 10 New Zealand rabbits. Subsequently, and during the same session, the implant with 1.5-2.0 mm of bone circumferentially was removed using a trephine bur and immediately transplanted in a through-and-through hole prepared in the contralateral aspect of the mandible. Three months following the transplantation, the animals were sacrificed and the mandibles processed for histological evaluation. The healing pattern was assessed in relation to (1) bone bridging at the interface between the bone core and the surrounding recipient osseous tissue, (2) differences in bone density between the transplanted bone cylinder and the bone at the margins of the recipient site, and (3) bone-to-implant contact (BIC) at the interface. The transplanted graft-implant cores were integrated within the recipient sites in five out of the 10 specimens while the remaining five bone-implant cores showed fibrous encapsulation. Various patterns of resorption were observed within the peri-implant transplanted hard tissues. Percentage BIC ranged between 1% and 72% in the fibrous-encapsulated specimens and between 20% and 62% in the integrated transplants. Within the limits of this pilot study, the results suggest that immediate transplantation of endosseous implants with their surrounding bone into congruous recipient osseous sites cannot predictably yield graft-implant incorporation and osseointegration of the implants. This alternative surgical modality of immediately transplanting a composite bone graft-implant from highly cortical intraoral or extraoral sites to enhance bone quality and/or volume in implant recipient sites such as the maxillary sinus and tuberosity areas needs to be further investigated.

Animals↗
PubMed2003

Genetic profile of clear cell odontogenic carcinoma.

In the head and neck region, clear cell tumors are usually derived from salivary glands, odontogenic tissues, and metastasis. The World Health Organization has classified clear cell odontogenic tumor among benign tumors, but it is now recognized as a more sinister lesion, and current opinion is that it should be designated as a carcinoma. It is characterized by aggressive growth, recurrences, and metastasis. By using complementary DNA microarrays, several genes in clear cell odontogenic tumor were identified that are differentially regulated when compared with non-tumor tissue. In conclusion, the first genetic profiling of clear odontogenic carcinoma is reported. DNA microarrays can potentially help in identifying some genes whose products could be disease-specific targets for cancer therapy as well as a tool for better classifying odontogenic tumor.

Adenocarcinoma, Clear Cell↗
PubMed2003

Calretinin expression in odontogenic cysts.

Calretinin is a calcium-binding protein with a possible role as a calcium buffer, calcium-sensor, or regulator of apoptosis. Calretinin is expressed in neural tissue, is a specific marker of mesothelial cells, and has been demonstrated in the odontogenic epithelium during odontogenesis in rat molar tooth germs. Moreover, it has been found to be expressed in a high proportion of solid, unicystic, and multicystic ameloblastomas, whereas, on the contrary, no positive staining has been found in odontogenic keratocysts, residual cysts, and dentigerous cysts. The purpose of this study was to evaluate calretinin expression in radicular cysts, follicular cysts, orthokeratinized keratocysts, and parakeratinized keratocysts. A total of 70 odontogenic cysts, 24 radicular cysts, 24 follicular cysts, and 22 odontogenic keratocysts (10 orthokeratinized keratocysts, 12 parakeratinized keratocysts) were evaluated. All the radicular cysts, follicular cysts, and orthokeratinized keratocysts were negative. However in 8 of 12 parakeratinized keratocysts, there was a positivity to calretinin in the parabasal-intermediate layers of the cyst epithelium. This positivity to calretinin in the parabasal layers in parakeratinized keratocysts, similar to that found for other markers like PCNA and p53, could point to an abnormal control of the cell cycle and could help to explain the differences in the clinical and pathologic behavior of odontogenic keratocysts, in particular the differences found between orthokeratinized keratocysts and parakeratinized keratocysts.

Basement Membrane↗
PubMed2003

Direct capping with four different materials in humans: histological analysis of odontoblast activity.

Pulp inflammation in restored teeth is mainly due to the presence of bacteria or bacterial products introduced by microleakage around the restoration or to the material toxicity. Recent knowledge has permitted a precise identification of the risks for pulpal irritation associated with adhesive materials and procedures. The purpose of this work was to evaluate the cellular events that occur in direct pulp exposure capped using different materials. Twenty-four vital teeth without caries, scheduled for extraction for orthodontic reasons, were selected. After a control of the hemostasis, each pulp was directly capped with a different material. The samples were randomly divided into four groups of six specimens each: group I: dental-bonding agent (Solist) followed by resin composite (Ecusit); group II: dental adhesive (Prompt) and resin composite (Pertac II); group III: traditional calcium hydroxide (Dycal) plus resin composite (Ecusit); group IV: light-curing calcium hydroxide (Ultrablend Plus) and amalgam (Dentsply). After 15 days the teeth were extracted, immediately fixed in 10% buffered formalin, embedded in resin (7200 Technovit), and prepared for thin ground sections with Precise 1 System. In the specimens of all groups, there were active odontoblasts near the composite resins and no newly formed dentin. Small quantities of inflammatory cells were present. A 1- to 3-microm layer zone of necrosis was present. In conclusion, all materials tested in this study induced similar tissue responses.

Analysis of Variance↗
PubMed2003

Crestal bone remodeling in loaded and unloaded implants and the microgap: a histologic study.

PURPOSE: The aim of this study was to histologically evaluate the crestal bone response to loaded and unloaded implants in beagle dogs. MATERIALS AND METHODS: Sand-blasted and acid-etched implants (Bone System, Milano, Italy) were placed in the mandible of six beagle dogs. The two premolars and the first molars had been extracted 3 months previously. Each dog received 12 implants in the mandible, and a total of 72 implants were used in this study. Three months after implantation, second-stage surgeries were performed for placement of abutments or healing screws. Three dogs were killed after 6 months, and three dogs were killed after 12 months. All 72 implants were retrieved. RESULTS: No statistically significant differences were found in the amount of bone loss between test and control implants, both at 6 and 12 months. Statistically significant differences were found, in both groups, between the bone loss observed at 6 months and that found at 12 months. CONCLUSION: Loading does not seem to be a relevant factor in the peri-implant bone resorption observed during the first year of function. Our results support previous findings that bone crest level changes could depend on the location of the microgap.

Acid Etching, Dental↗
PubMed2003

Histologic analysis of clinically retrieved immediately loaded titanium implants: a report of 11 cases.

BACKGROUND: Several investigators have reported high survival rates for early or immediately loaded dental implants. PURPOSE: The aim of the present study was to analyze histologically the periimplant tissue reactions and the bone-titanium interface of clinically retrieved immediately loaded titanium implants. MATERIALS AND METHODS: Eleven implants were inserted in the posterior jaw regions of six patients, serving as the most distal abutments of fixed provisional bridges and subjected to immediate occlusal loading. After a 10-month loading period, all 11 implants were retrieved with a trephine. RESULTS: Mature bone was present at the interface of all implants. Some vertical bone loss was observed; this was more pronounced for cylindric implants. The bone-implant contact was approximately 60 to 65% for all implants. CONCLUSIONS: The results demonstrate that osseointegration of dental implants can occur during immediate loading.

Adult↗
PubMed2003

Bone healing around titanium and titanium nitride-coated dental implants with three surfaces: an experimental study in rats.

BACKGROUND: Titanium nitride (TiN) has been used in many fields as a coating of surgical instruments, with the purpose of creating materials more resistant to wear and corrosion and also reducing adhesion. PURPOSE: The aim of this study was to evaluate the biocompatibility of TiN-coated dental implants. MATERIALS AND METHODS: Forty-five rats were used in this study. One hundred eighty 2 mm x 2 mm implants (P.H.I. San Vittore Olona, Milano, Italy) were used. The implants were divided into the following three groups: Group 1 (n = 60): 30 machined and 30 machined coated with Group 2 (n = 60): 30 sandblasted and 30 sandblasted coated with Group 3 (n = 60): 30 titanium plasma sprayed, 30 titanium plasma sprayed and coated with TiN Four implants were placed in each rat, two implants coated with TiN on the right tibia and two uncoated implants on the left. The animals were killed after 5, 10, 20, 30, or 60 days. Another 18 implants were used for surface roughness analysis. RESULTS: The present study showed that the healing around the TiN-coated implants was similar to that observed around the uncoated surfaces. CONCLUSIONS: TiN coating demonstrated a good biocompatibility, did not have untoward effects on the periimplant bone formation, and did not change the surface roughness values.

Animals↗
PubMed2003

Periimplant bone in immediately loaded titanium implants: histologic and histomorphometric evaluation in human. A report of two cases.

BACKGROUND: In recent years, several investigations have demonstrated, in clinical and histologic studies, the practicality of the use of immediate loading in implant dentistry. PURPOSE: The aim of the present study was to analyze the periimplant responses to immediately loaded implants retrieved from two patients after a 6-month loading period. MATERIALS AND METHODS: Three immediately loaded implants (two hydroxyapatite [HA] coated, one with a sandblasted surface) were retrieved from two patients after a 6-month loading period. The implants were treated to obtain thin ground sections. RESULTS: Bone was present at the interface with all three implants. Bone-implant contact percentage was 80.6% +/- 4.7. Bone was present also in the thread concavities found at a distance from preexisting bone and in those concavities that were at the interface with the supracrestal tissues or with wide marrow spaces. No gaps or fibrous tissues were present at the interface. No inflammatory infiltrate was present at the interface. The mean of the sulcus depth in all three implants was 0.9 +/- 0.1 mm, the length of the junctional epithelium was 0.9 +/-0.05 mm, and the length of connective tissue contact was 1.1 +/-0.05 mm. CONCLUSIONS; Our results show that immediate loading of dental implants did not impede the formation of mineralized tissue at the interface, and it can probably be a viable alternative in implant dentistry.

Alveolar Process↗
PubMed2003

Immediately loaded bar-connected implants with an anodized surface inserted in the anterior mandible in a patient treated with diphosphonates for osteoporosis: a case report with a 12-month follow-up.

BACKGROUND: It has been suggested that tooth loss is greater in the osteoporotic patient population. Only a few cases have been reported in the literature about the use of dental implants in patients with osteoporosis. Diphosphonates are stable analogs of pyrophosphate, a physiologic regulator of calcification and bone resorption. Multiple implant failures have been reported in a patient undergoing treatment with diphosphonates. Recently, several clinical and experimental reports have shown that immediate loading of dental implants is possible in selected situations. PURPOSE: The aim of this case report was to present the clinical outcome of immediate loading of implants in a patient undergoing diphosphonate treatment for osteoporosis. MATERIALS AND METHODS: In a 65-year-old patient undergoing diphosphonate treatment for osteoporosis, four implants were inserted in the anterior mandible. The implants were connected with a bar supporting an overdenture and were then loaded the same day. RESULTS: No problems occurred in the postoperative period. At 1-year follow-up, all four of the implants appeared to be clinically osseointegrated, and no mobility was present. Minimal bone resorption was present around all implants. CONCLUSIONS: Our case report points to the fact that, contrary to what has been reported in the literature, it is possible to successfully insert and load immediately after surgery dental implants in a patient undergoing diphosphonate treatment for osteoporosis.

Aged↗
PubMed2003

Osteoclast activity around loaded and unloaded implants: a histological study in the beagle dog.

The mechanisms of bone loss around dental implants are poorly understood. The osteoclast is the most important bone-resorbing cell. Humoral factors seem able to stimulate the differentiation of osteoclasts from mononuclear phagocytes. Bacterial lipopolysaccharides seem to be directly involved in inflammatory bone loss by stimulation of the survival and fusion of preosteoclasts. Excessive load seems to be able to cause bone loss. The aim of this paper was to evaluate the presence and number of osteoclasts in peri-implant bone in control (unloaded) and test (loaded) implants in order to determine if loading per se could be a contributing factor in peri-implant bone resorption. Forty-eight implants were inserted in the mandibles of 4 beagle dogs. After 3 months, a prosthetic superstructure was inserted on 24 implants, whereas in 24 implants only the healing screws were positioned. Twenty-four implants (12 test and 12 control) were retrieved at 6 months, and 24 implants (12 test and 12 control) were retrieved at 12 months. All implants were osseointegrated. The number of osteoclasts found in the crestal bone in the first 3 mm from the implant surface was evaluated. The mean number of osteoclasts were the following: control implants (6 months), 5.66 +/- 0.81; control implants (12 months), 2.55 +/- 1.05; test implants (6 months), 5.25 +/- 1.55; and test implants (12 months), 2.5 +/- 1.0. No statistically significant differences were observed between the control and test implants. According to our data, loading does not seem to have a relevant importance on the osteoclast activation in peri-implant bone.

Alveolar Bone Loss↗
PubMed2003

Bone response to zirconia ceramic implants: an experimental study in rabbits.

This study analyzes the bone response to zirconia ceramic implants inserted in New Zealand white mature male rabbits. The implants were inserted into the tibia, and each rabbit received 4 implants. All the animals were euthanatized after 4 weeks. A total of 20 implants were retrieved. Implants and surrounding tissues were immediately fixed in 4% paraformaldehyde and 0.1% glutaraldehyde in 0.15 molar cacodylate buffer at 4 degrees C and pH 7.4 to be processed for histology. The specimens were processed to obtain thin ground sections with the Precise 1 Automated System. The slides were observed in normal transmitted light under a Leitz Laborlux microscope. A great quantity of newly formed bone was observed in close contact with zirconia ceramic surfaces; in some areas, many osteoblasts were present directly on the zirconia. Percentage of bone-implant contact was 68.4% +/- 2.4%. Mature bone, with few marrow spaces, was present. Small actively secreting osteoblasts were present in the most coronal and apical portions of the implant. No inflamed or multinucleated cells were present. This study concluded that these implants are highly biocompatible and osteoconductive.

Animals↗