Histologic and histomorphometric evaluation of the bone response around a hydroxyapatite-coated implant retrieved after 15 years

Concerns have been raised about the degradation of hydroxyapatite (HA) coatings on dental implants over time. It has been speculated that the resorption of HA could produce a space between implant and bone, resulting in mechanical instability and implant failure. A screw-shaped HA-coated implant was retrieved after the abutment had fractured after a loading period of 15 years, and was evaluated histologically. At the interface with the implant, compact mature bone, with small marrow spaces, was present. Higher magnification showed that only a few osteoblasts were present. No multinucleated giant cells were present. Bone remodeling was evidenced by the presence of many secondary osteons close to the implant surface and many reversal lines. No fibrous or granulation tissues were present at the interface. The HA coating had been completely resorbed, and just 5.1% +/- 2.3% of the implant surface was covered by the HA coating. The bone-implant contact percentage was 77.6% +/- 5.1%. The almost complete resorption of the HA coating did not appear to have interfered with osseointegration. The implant was osseointegrated and was still providing adequate function; thus the HA coating resorption probably had little clinical significance.

Histologic evaluation of a provisional implant retrieved from man 7 months after placement in a sinus augmented with calcium sulphate: a case report

Little is known about the in vivo healing processes at the interface of implants placed in different grafting materials. For optimal sinus augmentation, a bone graft substitute that can regenerate high-quality bone and enable the osseointegration of load-bearing titanium implants is needed in clinical practice. Calcium sulphate (CaS) is one of the oldest biomaterials used in medicine, but few studies have addressed its use as a sinus augmentation material in conjunction with simultaneous implant placement. The aim of the present study was to histologically evaluate an immediately loaded provisional implant retrieved 7 months after simultaneous placement in a human sinus grafted with CaS. During retrieval bone detached partially from one of the implants which precluded its use for histologic analysis. The second implant was completely surrounded by native and newly formed bone, and it underwent histologic evaluation. Lamellar bone, with small osteocyte lacunae, was present and in contact with the implant surface. No gaps, epithelial cells, or connective tissues were present at the bone-implant interface. No residual CaS was present. Bone-implant contact percentage was 55% +/- 8%. Of this percentage, 40% was represented by native bone and 15% by newly formed bone. CaS showed complete resorption and new bone formation in the maxillary sinus; this bone was found to be in close contact with the implant surface after immediate loading.

Peri-Implant Bone Regeneration With Calcium Sulfate: A Light and Transmission Electron Microscopy Case Report

BACKGROUND

Calcium sulfate is a simple, biocompatible material with a very long, safe clinical history in several different fields of medicine. It is a rapidly resorbing material that leaves behind calcium phosphate lattice, which promotes bone regeneration.

OBJECTIVE

The aim of this study was a histological and ultrastructural evaluation of the tissues in a peri-implant site regenerated with calcium sulfate.

MATERIALS AND METHODS

The specimens were processed for observation under light and transmission electron microscopes.

RESULTS

In light microscopy, trabecular bone was present. No remnants of calcium sulfate were present. Transmission electron microscopy showed, in the areas of the interface with the implant surface, features of mature bone with many osteocytes. An amorphous layer and/or osteoid seam separated this mature bone from the metal surface.

CONCLUSION

The results confirm the high biocompatibility and rapid resorption of calcium sulfate.

Histologic Evaluation of a Provisional Implant Retrieved From Man 7 Months After Placement in a Sinus Augmented With Calcium Sulphate: A Case Report

Little is known about the in vivo healing processes at the interface of implants placed in different grafting materials. For optimal sinus augmentation, a bone graft substitute that can regenerate high-quality bone and enable the osseointegration of load-bearing titanium implants is needed in clinical practice. Calcium sulphate (CaS) is one of the oldest biomaterials used in medicine, but few studies have addressed its use as a sinus augmentation material in conjunction with simultaneous implant placement. The aim of the present study was to histologically evaluate an immediately loaded provisional implant retrieved 7 months after simultaneous placement in a human sinus grafted with CaS. During retrieval bone detached partially from one of the implants which precluded its use for histologic analysis. The second implant was completely surrounded by native and newly formed bone, and it underwent histologic evaluation. Lamellar bone, with small osteocyte lacunae, was present and in contact with the implant surface. No gaps, epithelial cells, or connective tissues were present at the bone–implant interface. No residual CaS was present. Bone–implant contact percentage was 55% ± 8%. Of this percentage, 40% was represented by native bone and 15% by newly formed bone. CaS showed complete resorption and new bone formation in the maxillary sinus; this bone was found to be in close contact with the implant surface after immediate loading.

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.

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.

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.

Maxillary sinus augmentation using granular calcium sulfate (surgiplaster sinus): radiographic and histologic study at 2 years

The main goal of sinus augmentation is the formation of vital bone to allow tissue integration of endosseous implants to support prosthetic rehabilitation. The aim of the present investigation was to evaluate the radiographic and histologic results when granular medical-grade calcium sulfate hemihydrate was used as a grafting material in sinuses. Forty implants plus grafting material were placed in 10 patients, representing 15 sinuses, using a one-stage technique. Radiographs were taken prior to sinus augmentation, monthly until 6 months postoperatively, 9 and 12 months after implant placement, and annually thereafter. Bone biopsies were harvested from all patients for histologic and histomorphometric evaluation.

Medial-grade calcium sulfate hemihydrate (surgiplaster) in healing of a human extraction socket--histologic observation at 3 months: a case report

PURPOSE

Following tooth extraction, wound healing is characterized by remodeling and resorption of the alveolar bone at the extraction site. This produces reduction in ridge volume. Medical-grade calcium sulfate hemihydrate (MGCSH) has been proposed as a graft material for extraction sockets to minimize the reduction in ridge volume. The aim of this study was to investigate the influence of MGCSH on the histopathologic pattern of intrasocket regenerated bone and to evaluate histologically the healed MGCSH-grafted extraction socket site at 3 months postextraction.

MATERIALS AND METHODS

MGCSH was grafted in a fresh human extraction socket, and at 3 months a cylindric tissue specimen, 2.5 mm in diameter, was trephined from the previously grafted site and an implant was placed. Non-decalcified specimens were sectioned at a horizontal plane and stained for histologic and histomorphometric evaluation.

RESULTS

The mean trabecular area was 58.6% +/- 9.2% in the coronal sections, 58.1% +/- 6.2% in the middle sections, and 58.3% +/- 7.8% in the apical sections. The differences in mean trabecular area between sections were not statistically significant.

DISCUSSION

It is significant that the MGCSH underwent complete resorption and replacement by newly formed bone because the most important negative attribute of other graft materials is the resorption time. Moreover, calcium sulfate shows great potential for guided bone regeneration in surgical sites.

CONCLUSION

MGCSH seems to be an acceptable graft material for extraction socket bone regeneration because it is completely resorbable and allows new trabecular bone arrangement in a limited 3-month period.

Medical grade calcium sulfate hemihydrate in healing of human extraction sockets: clinical and histological observations at 3 months

BACKGROUND

Following tooth extraction, remodeling and resorption of the alveolar bone at the extraction site characterize wound healing. This produces a reduction in ridge volume and difficulties in delayed placement of implants in an ideal position. Medical grade calcium sulfate hemihydrate (MGCSH) has been proposed as a graft material in extraction sockets to minimize the reduction in ridge volume. The aim of the present study was to investigate the influence of MGCSH on the histopathologic pattern of intrasocket regenerated bone and to evaluate histologically the healed MGCSH grafted extraction socket site 3 months postextraction

METHODS

MGCSH was grafted in 10 fresh human extraction sockets in 10 patients. Five post-extraction sockets were used as controls. At 3 months a cylindrical tissue specimen, 2.5 mm in diameter, was trephined from the previously grafted site followed by implant placement. Non-decalcified specimens were sectioned at a cross-horizontal plane and stained with fast green, toluidine blue, and Van Kossa stains for histological and histomorphometrical examination.

RESULTS

Histologically, MGCSH was not observed in most of the specimens. Newly formed bone with lamellar arrangements was identified in all the horizontal sections with no difference between apical, medium, and coronal areas. The mean trabecular area in the coronal sections was 58.6% +/- 9.2%; in the medium sections, 58.1% +/- 6.2%; and in the apical sections, 58.3% +/- 7.8%. The differences were not statistically significant.

CONCLUSION

MGCSH seems to be an ideal graft material in extraction socket bone regeneration because it is almost completely resorbable, and it allows a new trabecular bone arrangement at 3 months.

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.

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.

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.

The use of calcium sulphate in the surgical treatment of a 'through and through' periradicular lesion

AIM

This randomized, controlled, clinical study was designed to evaluate the adjunctive effect of calcium sulphate grafts on the surgical treatment of through and through periradicular lesions.

METHODOLOGY

Twenty patients each with one tooth showing evidence radiologically of a periradicular lesion wider than 10 mm, with lack of both buccal and lingual cortical bony plates and an indication for surgery were selected for the study. Ten teeth were treated with apicectomy, root-end filling and grafting of the bone defect with calcium sulphate prior to suturing (test group). The other 10 teeth received the same surgical therapy but no grafting with calcium sulphate (control group). The outcome of the healing process was evaluated at 6 and 12 months radiographically following the criteria reported by Rud and Andreasen.

RESULTS

At the six- and 12-month evaluation the test group had seven teeth with complete healing and two with incomplete healing, whilst the control group showed three teeth with complete healing, five with incomplete healing and one with unsatisfactory healing. One tooth in each group had to be extracted because of a vertical fracture that occurred during the follow-up period.

CONCLUSIONS

The results of the study demonstrate that the addition of calcium sulphate as a bone graft during the conventional surgical treatment of through and through lesions improves the clinical outcome. Histological analysis is desirable to investigate the quality of tissues formed using the two surgical procedures.

Bone regeneration with a calcium sulfate barrier

OBJECTIVES

Bone defects are a challenge for the dental clinician. As widely accepted in guided tissue regeneration, physically halting soft connective tissue proliferation into bone allows for bone regeneration. This concept is the "osteopromotion principle." The aim of this study was to assess the osteopromoting effect of calcium sulfate as a barrier.

STUDY DESIGN

Forty male Sprague-Dawley rats were used. Mucoperiosteal flaps were raised bilaterally at buccal and lingual aspects of the mandible to expose the angles. Next, 5 mm through-and-through bony defects were created bilaterally. On the test side, sterile medical grade prehardened calcium sulfate disks were applied both lingually and buccally to cover the defect. The control side defects were left uncovered. All flaps were sutured closed. Observation times were 3, 9, 18, and 22 weeks.

RESULTS

Histologic analysis demonstrated that at 3 weeks all test sites showed partial or complete bone healing. Similar findings were reported for all observation times. The control group showed no bone growth at 3 and 9 weeks and partial bone healing at 18 and 22 weeks.

CONCLUSIONS

This study indicates that calcium sulfate barriers can exclude connective tissues, allowing bone regeneration during healing.

Barrier membrane techniques in endodontic microsurgery

The ultimate goal in endodontic microsurgery is the predictable regeneration of periapical tissues. One of the main concerns in treating an endodontically treated tooth which has a through-and-through osseous defect is that incomplete bone healing may be inevitable. This article reviews the use of different barrier membranes for bone regeneration. In addition, the indications, techniques, and prognosis of calcium sulfate in guided bone regeneration are presented.

New directions in surgical endodontics; immediate implantation into an extraction site

Endodontic surgical procedures may reveal compromising factors that indicate a modification of the treatment (e.g. tooth extraction, root amputation, etc.). To take advantage of the osseous height and width, as well as the natural tooth angulation, immediate placement of implants after extraction is a reasonable alternative treatment. In this study, 32 titanium alloy implants were inserted immediately after extraction of teeth diagnosed during endodontic surgery as having root fractures, perforations, or endodontic-periodontal complications. After 4 to 6 months of osseointegration, only one implant failed to integrate, and the remaining implants were prosthetically restored. Sixteen months after occlusal loading, bone loss was approximately 1.5 mm for the 31 implants remaining. It seems that the immediate placement of implants following tooth extraction due to endodontic complications is a reliable procedure.

The guided tissue regeneration principle in endodontic surgery: one-year postoperative results of large periapical lesions

Twenty patients with large endodontic lesions, which failed to respond to conventional endodontic therapy, were selected for this study. The lesions had a radiographic diameter of at least 10 mm, were removed by periradicular surgery, before retrofilling the apices with either super EBA or dessicated zinc oxide-eugenol. In 10 test sites large e-PTFE membranes (Gortex) were placed to cover the lesions, while at the control sites the lesions were not covered before resuturing. Radio-graphic analysis of the lesions at 3, 6, 9 and 12 months revealed that lesions covered with the membranes healed quicker than the control lesions, and that the quality and quantity of the regenerated bone was superior when membranes were used. Results of the study indicate that guided tissue regeneration (GTR) principles can be effectively applied to the healing of large periapical lesions, especially in through-and-through lesions.

Guided tissue regeneration around dental implants in immediate extraction sockets: comparison of e-PTFE and a new titanium membrane

To evaluate the efficacy of guided tissue regeneration around exposed implant threads, 16 implants were placed into fresh extraction sockets in beagle dogs. Polytetrafluoroethylene (e-PTFE) membranes and titanium membranes were used to cover the defects around implants. A control group did not receive any membranes. Results were evaluated histologically. The average gain in bone height was 2.1 mm for e-PTFE sites, 0.8 mm for titanium membranes, and 2.9 mm for control sites. The greatest gain in bone levels was seen for two sites that received e-PTFE membranes and remained covered for the entire evaluation interval. Within the limits of this study, clinical and histologic evidence demonstrated that, when primary coverage is maintained, the use of e-PTFE membranes can significantly enhance bone regeneration around implants.

Use of dental operating microscope in endodontic surgery

Endodontic surgery is an alternative therapeutic approach to endodontic treatment. The outcome of the technique is affected by several factors, some of which can be eliminated by the use of a dental operating microscope. The microscope was used during the performance of 50 apicoectomies, with or without retrograde fillings. For clinical evaluation cases treated with the dental operating microscope were compared to cases treated without it. The postoperative evaluation showed a reduced incidence of symptoms in the cases treated with the dental operating microscope. More important, the dental operating microscope enhanced and facilitated each phase of endodontic surgery. Its use is highly recommended.