Biomedical subjects

Giovanna Iezzi

Publications and source records attributed to Giovanna Iezzi.

35 records · Page 2Linked to original sources

PubMed2004

Maxillary sinus augmentation with a synthetic cell-binding peptide: histological and histomorphometrical results in humans.

Bone substitutes should be used when sufficient amounts of autologous bone cannot be harvested from intraoral donor sites. P-15 is a highly conserved linear peptide with a 15 amino acid sequence identical to the sequence contained in the residues 766 to 780 of the alpha-chain of type I collagen. PepGen P-15 (Dentsply Friadent, Mannheim, Germany) is a combination of the mineral component of bovine bone (Osteograf/N 300) with P-15. Bio-Oss (Geistlich, Mannheim, Germany) is a deproteinized sterilized bovine bone with 75% to 80% porosity and a crystal size of approximately 10 microm in the form of cortical granules. The purpose of the present histological and histomorphometrical study was to compare maxillary sinus augmentation procedures in humans performed with PepGen P-15 with procedures associated with Bio-Oss and autologous bone. Seven patients participated in this study (3 men and 4 women; ages between 48 and 69 years, mean of 58 years) and were categorized into 3 groups. In group 1, a mixture of 50% autologous bone from an intraoral source and 50% Bio-Oss was used. In group 2, the graft materials used were 50% Bio-Oss and 50% PepGen P-15. In group 3, 50% autologous bone and 50% PepGen P-15 were used. Group 1 histomorphometry showed that the percentage of newly formed bone was 38.7% +/- 3.2%, marrow spaces represented 45.6% +/- 5%, and residual graft particles constituted the remaining 14.4% +/- 2.1%. Group 2 histomorphometry showed that newly formed bone represented 36.7% +/- 3.3%, marrow spaces represented 39.7% +/- 3.4%, and residual graft particles represented 19.6% +/- 2.1%. In group 3, newly formed bone represented 32.2% +/- 3.2%, marrow spaces represented 38% +/- 2.5%, and residual graft particles represented 28.8% +/- 1.1%. Non-statistically significant differences were found in the percentage of newly formed bone in the different groups (P = .360). Statistically significant differences were found in the percentage of residual graft materials among the different groups (group 1 vs groups 2 and 3) (P = .0001). These data demonstrate that the use of bone-replacement materials, without the addition of autologous bone, could be an alternative in sinus augmentation procedures. Such treatment would increase patient satisfaction, decrease surgical complications, and save the clinician substantial operating time.

Aged↗

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

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

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

Cortical bone regeneration with a synthetic cell-binding peptide: a histologic and histomorphometric pilot study.

PepGen P-15 is a combination natural anorganic bovine-derived hydroxyapatite matrix (ABM) coupled with a synthetic cell-binding peptide (P-15). This material has been reported to enhance bone formation in periodontal osseous defects. The aim of this study was to assess the effect of ABM/P-15 on the healing of cortical bone defects in rabbits. Five New Zealand rabbits were used. Two 8-mm bone defects were created in each tibia. Eight defects were filled with PepGen P-15, 8 defects with PepGen P-15 Flow, and 4 defects were used as a control group. A total of 20 defects were created. All rabbits were killed at 4 weeks. Block sections containing the defects were retrieved and the specimens processed for light microscopy examination. Newly formed bone was present in both test groups, whereas, in the control-group, only a scarce quantity of newly formed bone was present and the cortical defects had not been filled by the regenerated bone. Statistical evaluation showed that there were statistically significant differences between control sites and sites treated with P-15 and P-15 Flow (P = 0.0001), and also between sites treated with P-15 and P-15 Flow (P = 0.0001), respectively. No acute inflammatory infiltrate cells were visible in both of these groups. Both PepGen P-15 and PepGen P-15 Flow enhanced new bone formation in the cortical drilled defects, whereas control defects showed very little newly formed bone.

Animals↗

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

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 contact around acid-etched implants: a histological and histomorphometrical evaluation of two human-retrieved implants.

The surface characteristics of dental implants play an important role in their clinical success. One of the most important surface characteristics of implants is their surface topography or roughness. Many techniques for preparing dental implant surfaces are in clinical use: turning, plasma spraying, coating, abrasive blasting, acid etching, and electropolishing. The Osseotite surface is prepared by a process of thermal dual etching with hydrochloric and sulfuric acid, which results in a clean, highly detailed surface texture devoid of entrapped foreign material and impurities. This seems to enhance fibrin attachment to the implant surface during the clotting process. The authors retrieved 2 Osseotite implants after 6 months to repair damage to the inferior alveolar nerve. Histologically, both implants appeared to be surrounded by newly formed bone. No gaps or fibrous tissues were present at the interface. The mean bone-implant contact percentage was 61.3% (+/- 3.8%).

Acid Etching, Dental↗

PubMed2003

Role of the microgap between implant and abutment: a retrospective histologic evaluation in monkeys.

BACKGROUND: It has been hypothesized that a certain width of the peri-implant mucosa is required to enable a proper epithelial-connective tissue attachment and, if this soft tissue dimension is not adequate, bone resorption will occur to ensure the establishment of attachment with an appropriate biological width. The reason for the accelerated bone loss around submerged 2-piece implants in the first year after the restoration is not known, but one possibility is that the gap between components plays a role in this process. Recent studies have shown that for all 2-part implants, the bone crest level changes appeared dependent on the location of the microgap. METHODS: The aim of the present study was a retrospective histologic evaluation in monkeys of the bone response to implants inserted 1 to 2 mm above the alveolar crest (group 1, 15 implants), at the level of the alveolar crest (group 2, 12 implants), or 1 to 1.5 mm below the alveolar crest (group 3, 13 implants). These implants had been early loaded, immediately loaded, and inserted immediately postextraction. RESULTS: In group 1, a 0.13 +/- 0.12 mm bone increase in a coronal direction was seen. In group 2, a 2.1 +/- 0.29 mm vertical bone loss was present. In group 3, a mean 3.6 +/- 0.46 mm vertical bone loss extending in an apical direction was observed. Statistically significant differences were observed between all 3 groups. CONCLUSIONS: Our results confirm data published previously that if the microgap was moved coronally away from the alveolar crest, less bone loss would occur and if the microgap was moved apical to the alveolar crest, greater amounts of bone resorption were present. This remodeling is not dependent on early and immediate loading of the implants or on immediate postextraction insertion.

Alveolar Bone Loss↗

PubMed2003

Clinical and histologic aspects of dental implants removed due to mobility.

BACKGROUND: Implant failures are rare but do occur. Mechanical factors are certainly important in implant failures; so are biologic, iatrogenic, and functional factors. Mobility is the cardinal sign of implant failure. Three major etiologic factors have been suggested for implant failures: infection, impaired healing, and overload. The aim of the present study was to histologically and histochemically evaluate the fibrous connective tissue found around failed dental implants removed due to mobility. METHODS: In a 5-year period, 51 root-form implants were retrieved because of mobility and underwent histological examination. Thin ground sections were obtained from each implant. RESULTS: Almost all implants had been inserted in posterior (premolar-molar) regions of both jaws. In all specimens, there was the presence of a 600 to 1,100 microm thick connective tissue between implants and surrounding bone. In every case, the surrounding bone was compact and highly mineralized, with well-structured Haversian canals and few areas of remodeling. No bacteria were found in the most coronal portion of the implants. A scarce inflammatory cell infiltrate was present in the connective tissue of some specimens. In about 10% of specimens, the epithelium tended to surround the perimeter of the implant. CONCLUSION: Our histological results are consistent with the hypothesis that late failures of osseointegrated implants can be caused by a combination of poor bone quality, mechanical trauma to bone, and overloading forces.

Alveolar Process↗

PubMed2002

Intraduct papilloma of the palate. Report of a case.

Salivary gland papillomas are rare tumours arising from ductal epithelium. Intraduct papillomas are the most rare of all duct papillomas. Only four intraduct papillomas have been described in a review of nearly 3100 epithelial salivary tumours. Intraduct papillomas are located almost exclusively in the excretory ducts of the minor salivary glands. However, also the major salivary glands may be affected. Microscopically, the tumour consists of fibrovascular papillae covered by a columnar or cuboidal epithelium. The authors describe an intraduct papilloma of the palate in a 74-year-old woman. The excision of the lesion was curative.

Aged↗

PubMed2002

Prevalence of p53, bcl-2, and Ki-67 immunoreactivity and of apoptosis in normal oral epithelium and in premalignant and malignant lesions of the oral cavity.

PURPOSE: Loss of normal p53 is correlated to the progression of several preneoplastic lesions to neoplasms, and overexpression of bcl-2 determines an alteration of programmed cell death. There is an increased awareness of the importance of apoptosis in cancerogenesis, and a strong correlation of Ki-67 with high tumor grade has been reported. MATERIALS AND METHODS: The aim of our study was to investigate immunohistochemically the expression and relationship of p53, bcl-2, MIB-1, and the apoptotic index (AI) in normal oral epithelium, leukoplakia, dysplasia, and oral squamous cell carcinoma. RESULTS: A strong correlation was found between p53 overexpression and cell proliferation (MIB-1) and the AI. An inverse relationship was found between bcl-2 expression and MIB-1 and AI. A significant inverse relationship was found between p53 and bcl-2. A good positive correlation was present between AI and MIB-1 expression. CONCLUSIONS: Apoptosis could be important to help to understand oral carcinogenesis.

Apoptosis↗

PubMed2002

CD1a-positive cells in odontogenic cysts.

Langerhans cells (LC) are bone marrow-derived cells that have a CD1a-positive immunophenotype and are an important portion of the cell-mediated immune response. The aim of this study was an immunohistochemical evaluation of CD1a positive cells in different types of oral cysts. Fifty-five cysts were studied: 18 odontogenic keratocysts (OKC), of which five were orthokeratotic and 13 parakeratotic; 19 radicular cysts; and 18 dentigerous cysts. Positive LC was 80% for orthokeratotic OKC, 33% for parakeratotic OKC, approximately 35% for radicular cysts, and approximately 20% for dentigerous cysts. The results show that OKC with well-differentiated epithelial linings presented a greater number of LC than the other cysts. However, when the cyst wall was inflamed there were no differences in LC expression in the different types of cysts. The data confirm that LC distribution seems to be associated with the degree of differentiation of the epithelia.

Adult↗

PubMed2002

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

Benzenesulfonates↗

PubMed2002

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.

Alkaline Phosphatase↗

PubMed2002

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.

Analysis of Variance↗