Biomedical subjects

Giovanna Iezzi

Publications and source records attributed to Giovanna Iezzi.

At least 19 recordsLinked to original sources

PubMed2007

Influence of implant surface topography on early osseointegration: a histological study in human jaws.

The purpose of this study was to evaluate the influence of the oxidized surface on bone-to-implant contact (BIC%), the bone density in the threaded area (BA%), as well as the bone density outside the threaded area (BD%) in human jaws after 2 months of unloaded healing. Thirteen subjects (mean age 42.61 +/- 6.15 years) received two microimplants (2.5 mm diameter and 6 mm length) each, during conventional mandible or maxilla implant surgery. The microimplants with commercially pure titanium surfaces (machined) and oxidized surfaces served as the control and test surfaces, respectively. After 2 months, the microimplants and the surrounding tissue were removed and prepared for histomorphometric analysis. All microimplants, except two machined and one oxidized microimplant surfaces, were found to be clinically stable after the healing period. Histometric evaluation indicated that the mean BIC% was (21.71 +/- 13.11)% and (39.04 +/- 15.75)% for machined and oxidized microimplant surfaces, respectively. The BD% was higher for the oxidized surface, although there was no difference for maxilla and mandible. The oxidized surface impacted the BA% for the type-IV bone. Data suggest that the oxidized surface presented a higher bone-to-implant contact rate compared with machined surfaces under unloaded conditions, after a healing period of 2 months.

Adult↗

PubMed2007

Wide-diameter implants: analysis of clinical outcome of 304 fixtures.

BACKGROUND: In the last decade, the use of wide-diameter implants (WDIs; diameter >3.75 mm) has increased. Although good clinical outcomes have been reported in recent literature, there are few reports on this topic. Thus, we planned a retrospective study on a large series of WDIs to evaluate the clinical outcome. METHODS: From October of 1996 to December of 2004, 205 patients were operated on, and 304 WDIs were inserted. The mean postloading follow-up was 30 months. Implant diameter and length ranged from 5.0 to 6.5 mm and from 8.0 to 15 mm, respectively. Because only five of 304 implants were lost (i.e., a survival rate of 98.4%) and no statistical differences were detected among the studied variables, no or reduced crestal bone resorption (CBR) was considered an indicator of success to evaluate the effect of several host-, surgery-, and implant-related factors. A general linear model (GLM) was performed to detect variables that were associated statistically with CBR. RESULTS: Only five of 304 WDIs were lost, and no differences were detected among the studied variables. On the contrary, the GLM showed that distal teeth (i.e., premolars and molars), small implant diameter (i.e., 5.0 and 5.5 mm), and short implant length (i.e., <13 mm) correlated with a statistically significant lower CBR. CONCLUSION: The use of WDIs is a viable treatment option, and it may provide benefits in posterior regions for long-term maintenance of various implant-supported prosthetic rehabilitations.

Adolescent↗

PubMed2006

Comparative evaluation of the peri-implant bone tissue mineral density around unloaded titanium dental implants.

OBJECTIVE: The mechanical properties of bone are greatly influenced by the percentages of organic and mineral constituents. Nevertheless, the information about the mineral content on a microscopic scale in peri-implant bone is scarce. The aim of this work was to analyze the bone mineral density of peri-implant bone under different techniques. DESIGN: Five unloaded titanium dental implants with a micro-structured surface (three XiVE plus and two Frialit 2, DENTSPLY-Friadent, Mannheim, Germany) were retrieved from the mandible of five patients after a 6-month period. scanning electron microscopy with backscattered electron signal (BSE), light microscopy (LM) with a double staining technique, fluorescence microscopy and confocal laser microscopy were used for measuring microscopic mineral content variations in peri-implant bone. Histomorphometry and image intensity (grey level) were evaluated using a software package for image analysis. RESULTS: The low mineral density index (LMDI) for LM was of 29.2+/-3.1 (mean+/-S.D.), while the high mineral density index (HMDI) was of 88.2+/-3.6 (mean+/-S.D.). The one-way ANOVA analysis showed a significant difference (P<0.001) among the groups. The pairwise Holm-Sidak test identified the differences among HMDI indexes for both LM and SEM values and also for cross-evaluation of the LMDI and HMDI values. The comparison between LMDI indexes for both SEM and LM did not show any significance. The fluorescence microscopy analysis showed clearly the difference between old (high mineralized) and new (low mineralized) bone tissue near the implant surface. Under confocal laser microscopy the same sections showed the area of bone modelling closest to implant surface. CONCLUSION: In this study it was found that bone around unloaded implants showed a low mineral density index under all the investigation methods used. It was also found that the conventional LM technique with the double staining method was able to intensely stain the bone area with a low mineral content.

Analysis of Variance↗

PubMed2006

Collagen fiber orientation near a fractured dental implant after a 5-year loading period: case report.

PURPOSE: Fracture of an implant is one of the possible complications of dental implants. It is a quite rare event but of high clinical relevance. Nevertheless, it represents an important opportunity for evaluating the peri-implant bone-tissue response to implant overloading in human beings. The aim of the present study was a scanning electron microscopy evaluation of a screw-shaped implant retrieved because of fracture and a birefringence analysis of the tissue near the fractured implant. MATERIALS AND METHODS: There was 1 fractured screw-shaped implant retrieved from a patient with a trephine bur, and it was processed for histology. The specimen was analyzed under both scanning electron microscopy and circularly polarized light microscopy. RESULTS: The scanning electron microscopy fractography analysis showed the typical signs of a fatigue-fracture, with large plastic deformations on the implant. The fracture seemed to start from the internal coil of the implant. Under circularly polarized light microscopy investigation, a bone-implant contact percentage of 81.6% +/- 1.5% (mean +/- standard deviation) was found. The amount of the transverse collagen fibers was of 68.3%, and the amount of the longitudinal collagen fibers was of 31.7%. The difference was statistically significant for z = 2.247 (P = 0.025). CONCLUSION: The fracture of the implant was most probably correlated to a fatigue of the material mainly associated to a lesion of the internal coil. The high level of bone-implant contact percentage was correlated to a predominant transverse collagen fiber orientation of the collagen fibers in the peri-implant bone.

Bone Remodeling↗

PubMed2006

Maxillary sinus augmentation with different biomaterials: a comparative histologic and histomorphometric study in man.

OBJECTIVE: Rehabilitation of the edentulous posterior maxilla with dental implants can be difficult because of insufficient bone volume caused by pneumatization of the maxillary sinus and crestal bone resorption. Different biomaterials have been used for sinus augmentation. The aim of the study was to compare different materials in maxillary sinus augmentation in man. METHODS: A total of 94 patients participated in this study. Inclusion criteria were maxillary partial (unilateral or bilateral) edentulism involving the premolar/molar areas, and the presence of 3-5-mm crestal bone between the sinus floor and alveolar ridge. A total of 362 implants were inserted. There were 9 biomaterials used in the sinus augmentation procedures. Each patient underwent 1 biopsy after 6 months. A total of 144 specimens were retrieved. RESULTS: None of the 94 patients had complications. All implants were stable, and x-ray examination showed dense bone around the implants. Mean follow-up was 4 years. There were 7 implants that failed. Histologic resultsshowed that almost all the particles of the different biomaterials (i.e., autologous bone, demineralized freeze-dried bone allograft Biocoral [Inoteb, St. Gonnery, France], Bioglass [US Biomaterials, Alachua, FL], Fisiograft [Ghimas, Bologna, Italy], PepGen P-15 [Dentsply Friadent CeraMed, Lakewood, CO], calcium sulfate, Bio-Oss [Geistlich Pharma AG, Wohlhusen, Switzerland], and hydroxyapatite) were surrounded by bone. Some biomaterials were more resorbable than others. Included are the histomorphometry clarified features of the newly formed bone around the different grafted particles. CONCLUSION: All biomaterials examined resulted in being biocompatible and seemed to improve new bone formation in maxillary sinus lift. No signs of inflammation were present. The data are very encouraging because of the high number of successfully treated patients and the good quality of bone found in the retrieved specimens.

Aged↗

PubMed2006

Histologic evaluation of 3 retrieved immediately loaded implants after a 4-month period.

OBJECTIVE: To perform a histologic and histomorphometric analysis of the peri-implant tissue reactions and bone-titanium interface in 3 immediately loaded (provisional loaded) titanium implants retrieved from a man after a loading period of 4 months. MATERIALS & METHODS: A 35-year-old patient with a maxillary partial edentulism did not want to wear a provisional removable prosthesis during the healing period. It was decided to insert 3 definitive implants and use 3 provisional implants for the transitional period. The provisional implants were loaded the same day with a resin prosthesis in occlusal contact. During the second surgical phase, after 4 months, the provisional prosthesis was removed, and the provisional implants were retrieved with a trephine bur. Before retrieval, all implants appeared to be clinically osseointegrated. The specimens were processed for observation under light microscopy. RESULTS: At low magnification, it was possible to observe that bone trabeculae were present around the implant. Areas of bone remodeling and haversian systems were present near the implant surface. Under polarized-light microscopy, it was possible to observe that in the coronal aspect of the thread, the lamellar bone showed lamellae that tended to run parallel to the implant surface, while in the inferior aspect of the thread, the bone lamellae ran perpendicular to the implant surface. CONCLUSIONS: Histologic data pertaining to these 3 immediately loaded implants, and retrieved after a 4-month loading period, show that immediate loading did not produce untoward effects on peri-implant bone healing.

Adult↗

PubMed2006

Correlation between implant stability quotient and bone-implant contact: a retrospective histological and histomorphometrical study of seven titanium implants retrieved from humans.

BACKGROUND: Primary stability has a relevant role in the long-term success of dental implants. A quantitative method for the measurement of implant stability has been introduced (resonance frequency analysis [RFA]). Information about the significance of RFA measurements and about the relationship between RFA values and their association with implant osseointegration, success, or failure is important from a clinical point of view. PURPOSE: The aim of the present histological and histomorphometric study was to see if a correlation existed between the bone-implant contact (BIC) percentage of retrieved human implants and RFA values. MATERIALS AND METHODS: Seven implants inserted in the posterior mandible, with a sandblasted and acid-etched surface and retrieved after a 6-month period, were evaluated in the present study. These seven implants had been retrieved for different causes. All these implants were submerged and were retrieved with a 5-mm trephine bur and immersed in 10% buffered formalin to be processed for histology. RESULTS: A statistically significant correlation could be detected between implant stability quotient and BIC (p=.016). CONCLUSIONS: Even if the relationship between bone structure and RFA is still not fully understood, in our study, a statistically significant correlation was found between RFA and BIC values. Further studies are needed to evaluate a correlation of RFA and BIC in human implants retrieved after a range of healing periods.

Dental Implantation, Endosseous↗

PubMed2006

Preferred collagen fiber orientation human peri-implant bone after a short- and long-term loading period: a case report.

Immediate loading of dental implants offers treatment cost advantages to patients and avoids the functional and psychological problems caused by the wearing of provisional dentures. There is evidence that the amount of transverse collagen fiber orientation in bone is influenced by mechanical stresses and strains. Two osseointegrated dental implants in humans were used in the present study. Two implants inserted in the maxilla were analyzed: 1 short-term implant (implant A) immediately loaded and retrieved after 4 months of loading and 1 long-term implant (implant B) immediately loaded and retrieved after 12 years. We hypothesized that the bone functional strain caused by immediate loading correlated well with the collagen fiber organization occurring after both short- and long-term functional healing. Circularly polarized light (CPL) was used to assess the area fraction extension related to the transverse collagen fiber orientation in the bone matrix. After evaluating a total of 68 digitized images taken at x50 magnification, birefringence measurements were performed all around the implant surfaces by using 2 central sections from each implant. The results showed that the bone-to-implant contact (BIC) percentage for implant A was 67.9% +/- 9.5% (mean +/- SD), whereas the BIC percentage for implant B was 74.6% +/- 11.2% (mean +/- SD). The area fraction extension was 2.7% +/- 1.4 % (mean +/- SD) for implant A, whereas the area fraction extension was 4.7% +/- 1.2% (mean +/- SD) for implant B. The CPL measurements of the birefringence for transverse collagen fibers of implant A vs implant B indicated that the bone fraction area difference was not high. In the bone near both dental implants, no differences were found in the amount of transverse collagen fibers. Immediate loading seemed to determine and maintain the collagen fiber's orientation over a long period.

Adult↗

PubMed2006

Immediately loaded blade implant retrieved from a after a 20-year loading period: a histologic and histomorphometric case report.

Immediate loading of root-form dental implants has shown promising results and offers treatment cost and convenience advantages to patients. Although blade implants have been immediately loaded for over 2 decades, the ability of this implant design to achieve osseointegration has been debated. The aim of the present study was to histologically evaluate the peri-implant tissues of an immediately loaded blade implant retrieved for abutment fracture after a 20-year loading period. Histologic samples were prepared and examined by light microscope. Compact, cortical, mature bone with well-formed osteons was present at the interface of the implant. Bone-to-implant contact was 51% +/- 6%. The histologic data showed that osseointegration was obtained in an immediately loaded blade implant inserted into the mandible, and that mineralized tissues were maintained at the interface over a long period (20 years).

Blade Implantation↗

PubMed2006

Maxillary sinus augmentation using an engineered porous hydroxyapatite: a clinical, histological, and transmission electron microscopy study in man.

Porous hydroxyapatite (HA) is a calcium-phosphate-based material that is biocompatible, nonimmunological, and osteoconductive, and has a macroporosity of about 200 to 800 microm. The pores seem to be able to induce migration, adhesion, and proliferation of osteoblasts inside the pore network and to promote angiogenesis inside the pore system. The aim of this study was to evaluate the clinical behavior and the histological and ultrastructural aspects of porous HA in maxillary sinus augmentation procedures. Twenty-four patients (19 men, 5 women; average age 53.4 years) in good general physical and mental health and with partially or completely edentulous maxillae were selected for this study. Six months after sinus floor elevation, at the time of dental implant placement, biopsies were carried out under local anesthesia. These bone cores were cut in half and were processed for light and transmission electron microscopy. After a mean 3 years after implantation, all implants are clinically in function and no surgical or prosthetic complications have occurred. Under light microscopy, newly formed bone was 38.5% +/- 4.5%, whereas the residual biomaterial represented 12% +/- 2.3% and the marrow spaces represented 44.6% +/- 4.2%. In addition, in the majority of cases, the biomaterial particles were in close contact with the bone, which appeared compact with the characteristic features of well-organized lamellar bone. A cement-like line was slightly visible at the bone-biomaterial interface, but there were no gaps or interposed connective tissue in between. A high quantity (about 40%) of newly formed bone was present. Bone was closely apposed to the biomaterials particles as shown in light microscopy and transmission electron microscopy. Moreover, no signs of inflammatory cell infiltrate or foreign body reaction were present. Also, most of the biomaterial was resorbed and only a small quantity (a little more than 10%) was still present. The results of our study show that porous HA can be a suitable synthetic material for bone regeneration in maxillary sinus augmentation procedures.

Absorbable Implants↗

PubMed2006

Histological evaluation, in rabbit tibiae, of osseointegration of mini-implants in sites prepared with Er:YAG laser versus sites prepared with traditional burs.

OBJECTIVE: The aim of this study was to evaluate the different bone reactions in rabbit tibiae after the insertion of mini-implants by using two different techniques of site preparation: the superpulsed Er:YAG laser (VPS system) versus the traditional technique with burs. METHODS: One mm wide and 2 mm long implant sites were made in the tibiae of 12 rabbits (8 for each tibia): the authors used an Er:YAG laser with a sapphire tip on a contra-angle hand piece with a 1.0 mm diameter in a VPS mode (with 200 mJ and 30 Hz) to make 4 bone sites and a calibrated traditional bur to drill the other 4 sites in each tibia. The authors inserted a threaded mini-implant, with a sandblasted and acid-etched surface, in the 2 laser implant sites and in the 2 drilled sites of each tibia. The other sites were used as controls. At 0, 7, 15, 30, 45, and 60 days from the surgery, 2 animals each were euthanized, and the retrieved specimens were evaluated. RESULTS: No implant was lost, and the osseointegration was comparable in all implant sites. Histologically, in the 7- and 15-day postoperative specimens, the laser sites showed some amorphous tissue caused by the carbonization of bone during the laser procedure. The sites without implants showed good regeneration of the bone: it was faster in the drill defects because in the laser ones there was some carbonized amorphous tissue. After 30 days postoperatively, the regeneration was the same in all sites. CONCLUSIONS: In comparison with the traditional drilling procedures, Er:YAG laser can be considered efficient in surgery of the bone without inducing irreversible damages, even if it is possible to observe the presence of some carbonized amorphous tissue in the early part of the healing process. This tissue is progressively resorbed in a way similar to a bone graft and doesn't impede the bone formation and osseointegration processes. Further clinical and histological studies are necessary to better define this amorphous tissue and an efficient and safe operative protocol in the surgery of bone with an Er:YAG laser.

Animals↗

PubMed2006

Histologic evaluation of early human bone response to different implant surfaces.

BACKGROUND: Studies have demonstrated that roughened dental implant surfaces show firmer bone fixation and an increased percentage of bone-to-implant contact (BIC%) compared to commercially pure titanium-surface (machined) implants. Therefore, the purpose of this study was to evaluate the influence of implant-surface topography on human bone tissue after 2 months of unloaded healing. METHODS: Fourteen subjects with a mean age of 46.87 +/- 9.45 years received two microimplants each (2.5 mm in diameter and 6 mm in length), one test (sandblasted acid-etched surface) and one control (machined surface), either in the mandible or in the maxilla. After a healing period of 2 months, the microimplants and surrounding tissues were removed with a trephine bur and prepared for histologic analysis. RESULTS: All microimplants, except for one of the controls, were clinically stable after the healing period. Histometric evaluation indicated that the mean BIC% was 23.08% +/- 11.95% and 42.83% +/- 9.80% for machined and rough microimplant surfaces, respectively (P = 0.0005). The bone area within the threads was also higher for sandblasted-surface implants (P = 0.0005). The mean percentage of bone density did not differ between the two groups (P = 0.578). CONCLUSION: Data from the present histological study suggest that the sandblasted acid-etched implant provides a better human bone tissue response than machined implants under unloaded conditions after a healing period of 2 months.

Acid Etching, Dental↗

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

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

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↗

PubMed2004

Bone-defect healing with calcium-sulfate particles and cement: an experimental study in rabbit.

Calcium sulfate (CaS) has been shown to be a reasonable alternative to autogenous bone graft for treating bone lesions in dentistry. The aim of this work was an histological study of the bone healing of defects treated with calcium sulfate in the form of cement or beads, in animal. Eight New Zealand rabbits, weighing about 2.5 Kg were used in this study. In each rabbit, four 6 mm bone defects were created in the tibial metaphysis. The 2 defects in the right tibia were filled with calcium sulfate as cement, while the 2 defects in the left one were filled with calcium sulfate as beads. Four rabbits were killed after respectively 2 and 4 weeks, with an intravenous injection of Tanax, and the block sections, containing the bone defects, were retrieved. A total of 16 defects filled by cement and a total of 16 defects filled by beads were retrieved. The specimens were processed to obtain thin ground sections with the Precise 1 Automated System. In the first phases of healing it was possible to observe an intense osteoblastic activity, and in some areas osteoid matrix was present. After two weeks the calcium sulfate (both cement and beads) was still present, and biological fluids and cells were present inside the material. Newly formed bone surrounded the calcium sulfate and filled about 10% of the defect. After four weeks the calcium sulfate was almost completely resorbed and substituted by new bone. Approximately 34% of the defects were filled by newly formed bone. BEI and XRM evaluations showed the structural components of the filled defects. In none of the specimens were inflammatory cells present. No significant differences were found using both calcium sulfate as cement and beads, and they both have shown a high biocompatibility, appearing to promote newly bone formation in the rabbit model, and they did not induce any untoward effect on the bone regeneration processes.

Absorptiometry, Photon↗