Antonio Scarano

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-15TM [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.

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.

High-precision, cost-effective cutting system for producing thin sections of oral tissues containing dental implants

A new high-precision, cost-effective cutting system, able to produce thin (20-30 microns) sections of oral tissues, containing dental implants, is presented. With this system the authors have been able to obtain, in a reproducible and consistent way, thin slides containing biomaterials and biological tissues. Very high cellular detail was possible, even at high magnifications (x 1200). Histochemical reactions (e.g. acid and alkaline phosphatases) have also been obtained in a reproducible way, without sputter ground staining. The time involved in specimen cutting was significantly reduced, and about five slides per specimen were obtained with minimal loss of tissue. In almost all cases it has been possible to eliminate the grinding process with its inherent problems, such as formation of ledging at the bone-titanium interface. With this system it was also possible to obtain thin slides of soft tissue lesions (i.e. benign mucous membrane pemphigoid).

Comparison of bone regeneration with the use of mineralized and demineralized freeze-dried bone allografts: a histological and histochemical study in man

Mineralized (FDBA) and demineralized freeze-dried bone allografts (DFDBA) have been proposed as substitutes for autologous bone in oral surgery. The demineralization process has been shown, in rodents, to determine osteoinduction in tissues other than bone. Other investigators have reported poor clinical results, in man, with the use of DFDBA. The aim of the present study was a comparative light microscopical and histochemical analysis of bone regeneration processes, in man, with the use of FDBA and DFDBA. Our histological results showed that in DFDBA only the particles near the host bone were involved in the mineralization processes, while in FDBA even the particles that were farthest from the host bone were lined by osteoblasts, actively secreting osteoid matrix and newly formed bone. These results probably point to a more osteoconductive effect of FDBA. No osteoinduction was observed with FDBA or DFDBA.

Clinical and histologic aspects of biphasic calcium phosphate ceramic (BCP) used in connection with implant placement.

A granulate of biphasic calcium phosphate ceramic (BCP), composed of 50% hydroxyapatite and 50% beta-tricalcium phosphate, was used, in man, to fill defects resulting from cyst enucleation. The defects were covered with e-PTFE membranes, and at the re-entry procedure after six months, it was possible to see that the defects were filled by a newly formed tissue with the macroscopic features of mature bone. Smooth titanium implants were inserted in the newly regenerated tissue. Histological examination of this tissue showed that most of the particles were lined by newly formed bone. Some particles were undergoing resorption processes and were being gradually substituted by newly formed bone. No inflammatory infiltrate was present. Our results point, in conclusion, to a good biocompatibility and osteoconductivity of this material.

Bacterial adhesion on titanium nitride-coated and uncoated implants: An in vivo human study

Titanium nitride (TiN) has been used in many fields as a surgical instrument coating that makes the surgical materials more resistant to wear and corrosion. The aim of the present study was an in vivo evaluation of the bacterial adhesion to TiN-coated (test) and uncoated (control) titanium implants. Six patients aged between 21 and 25 years and in excellent systemic health participated in the study. All of the participants gave their informed consent. The participants were selected on the basis of good periodontal health and no signs of mouth breathing. In each of the 6 participants, a removable acrylic device was adapted to the molar-premolar region of each quadrant of the jaws. One 4 x 13 mm titanium implant was glued to the buccal aspect of each device. The plasma spray covered 11.5 mm of the body of the implant, whereas the neck was machined titanium. Test implants were glued to the right devices and control implants were glued to the left devices. After 24 hours, the implants were removed from each device and processed for scanning electron microscopy for evaluation of the machined portion of the implant covered by bacteria. A total of 24 implants were used in this study, 12 test and 12 control. Surface characterization of the machined portion of the neck of the implant was performed on an additional 10 implants (5 test and 5 control). On test implants the implant surface covered by bacteria was significantly lower compared with that of control implants (P = .0001). The surface roughness was similar in both groups. TiN surfaces showed a significant reduction of the presence of bacteria, and this fact could probably be important in the decrease of the inflammation of the peri-implant soft tissues.

Clinical and histological results in alveolar ridge enlargement using coralline calcium carbonate.

A very important parameter during the insertion of dental implants is the amount of bone present in a site. A regenerative procedure to increase the width and the height of bone is proposed with the use of occlusive barrier membranes and biomaterials. The authors used, in six patients with deficient alveolar ridges, prior to implant insertion, Biocoral gel particles in connection with expanded polytetrafluoroethylene membranes. After 6 months it was observed that a tissue similar to mature bone had regenerated under the membrane and microscopically it was observed that the Biocoral particles were still present and almost all were completely surrounded by mature bone.

Evaluation of guided bone regeneration in rabbit tibia using bioresorbable and non-resorbable membranes

The aim of this study was an evaluation of the possibility of bone regeneration in connection with implant placement, using a new bioresorbable membrane (Guidor Matrix Barrier) used previously in periodontal tissues regeneration. The study compared the bone regeneration obtained around Bonefit-ITI implants inserted in rabbit tibia using Guidor membranes, Gore-Tex membranes and in control sites. Microscopic analysis was performed after 6, 9 and 12 weeks. It was possible to see that the amount of bone around implants covered by Guidor and Gore-Tex membranes was roughly equivalent in all experimental sites at the 6-, 9- and 12-week time intervals. Also, all control sites healed completely. It could be concluded from this study that: (1) rabbit tibia cannot be recommended in research connected with guided bone regeneration, as all control sites healed in the same way as the test sites; (2) in no case did the presence or the degradation of the resorbable membrane prevent the formation of new bone; (3) no inflammatory reaction was present around the bioresorbable and the non-resorbable membranes; (4) bone formed in all cases on the outer surface of the non-resorbable membranes; (5) large Guidor membrane fragments were present in the 6-week specimens, while in the 12-week specimens only small fragments were recognizable; (6) Guidor membranes can be used in guided bone regeneration.

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.

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.