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.     

Effect of RGD peptide coating of titanium implants on periimplant bone formation in the alveolar crest. An experimental pilot study in dogs

The aim of the present study was to analyse the effect of organic coating of titanium implants on periimplant bone formation and bone/implant contact. Three types of implants were used: (i) Ti6Al4V implants with polished surface (control 1) (ii) Ti6Al4V implants with collagen coating (control 2) (iii) Ti6Al4V implants with collagen coating and covalently bound RGD peptides. All implants had square cross-sections with an oblique diameter of 4.6 mm and were inserted press fit into trephine burr holes of 4.6 mm in the mandibles of 10 beagle dogs. The implants of five animals each were evaluated after a healing period of 1 month and 3 months, during which sequential fluorochrome labelling of bone formation was performed. Bone formation was evaluated by morphometric measurement of the newly formed bone around the implant and the percentage of implant bone contact. After 1 month there was only little bone/implant contact, varying between 2.6 and 6.7% in the cortical bone and 4.4 and 5.7% in the cancellous bone, with no significant differences between the three types of implants. After 3 months, implants with polished surfaces exhibited 26.5 and 31.2% contact in the cortical and cancellous bone, respectively, while collagen-coated implants had 19.5 and 28.4% bone contact in these areas. Implants with RGD coating showed the highest values with 42.1% and 49.7%, respectively. Differences between the surface types as such were not significant, but the increase in bone/implant contact from 1 to 3 months postoperatively was significant only in the group of RGD-coated implants (P = 0.008 and P = 0.000). The results of this pilot study thus provide only weak evidence that coating of titanium implants with RGD peptides in the present form and dosage may increase periimplant bone formation in the alveolar process. The results therefore require further verification in a modified experimental setting.     

Histologic results from a human implant retrieved due to fracture 5 years after insertion in a sinus augmented with anorganic bovine bone

BACKGROUND: Little is known about the healing pattern and the osseointegration processes at the interface of implants placed into different grafting materials in man. Anorganic bovine bone (ABB) is a xenogenic material with a high biocompatibility and osteoconductivity. METHODS: A 47-year-old patient underwent a monolateral sinus-augmentation procedure using 100% ABB. Two titanium dental implants were inserted at the same time as the grafting procedure. After 6 months, a fixed prosthetic restoration was placed. After a 5-year loading period, the distal implant fractured, and the implant was removed with a 5-mm trephine bur. RESULTS: At low magnification, in the peri-implant bone in the grafted area, many particles of ABB were still present. Bone was always interposed between the ABB particles and the metal surface, and in no case were the graft particles in contact with the implant. No acute or chronic inflammatory cell infiltrate or foreign body reactions were present around the particles or at the bone-implant interface. The tissues around the implant were composed of 40% +/- 2.4% bone, 12% +/- 2.9% ABB particles, and 50% +/- 6.2% marrow spaces. The percentage of bone-to-implant contact was 48.6% +/- 3.7%. CONCLUSIONS: A high percentage (~50%) of direct contact between bone and implant, without the interposition of graft material particles, was present. ABB had enabled implant integration to take place, which had remained stable for 5 years.     

Postmortem histologic evaluation of mandibular titanium and maxillary hydroxyapatite-coated implants from 1 patient.

Postmortem examination of human specimens is an extremely important aspect of evaluating the relative compatibility and long-term success of endosseous implant surfaces. The bone-implant interface of 5 commercially pure titanium screw-type mandibular implants after 85 months of service and 2 hydroxyapatite- (HA) coated maxillary implants after 38 months of service were examined. All implants were stable at the time of the patient's death. The mandibular implants had an average of 65% contact with bone and the maxillary implants had an average of 47% contact. The HA coating had separated from the maxillary implants in some areas and was free within surrounding connective tissue or surrounded by invaginating sulcular epithelium. The arrangement and pattern of bone contact appeared different between HA-coated and titanium implant surfaces.     

3D打印和CAD/CAM氧化锆种植体骨结合性能的动物实验评价

目的 比较3D打印和计算机辅助设计与制造(CAD/CAM)氧化锆种植体与纯钛种植体在动物体内的骨结合和成骨效果的差异,评价氧化锆种植体骨结合性能.方法 分别将3D打印氧化锆、CAD/CAM种植体和钛种植体各20枚随机植入6只Beagle犬的胫骨内,8周后观察氧化锆种植体的成功率和骨结合能力,并与钛种植体进行比较,观察指...     

Immediate loading with complete implant-supported restorations in an edentulous heavy smoker: histologic and histomorphometric analyses

The clinical case presented is that of an edentulous female patient, a heavy smoker, who received implant-supported complete restorations in the maxilla and mandible using the immediate loading concept according to the Ankylos implant system. The patient received 12 commercially pure titanium (grade 2) Ankylos implants, 6 in the maxilla and 6 in the mandible. The implants were loaded immediately after surgery with temporary acrylic resin prostheses fabricated chairside using a prefabricated customized splint. The definitive ceramometal restorations were seated 4 months after surgery. Clinical and radiologic evaluation at 7 months after implant placement indicated functional bone anchorage of all implants, despite the patient being a smoker and having poor bone quality. The patient died 7 months after implant placement because of lung cancer; however, there was no known disease at the time of implant placement. After her death, the implants with the surrounding tissues were removed en bloc and examined histologically and histomorphometrically using undecalcified cut and ground sections. All implants were osseointegrated to some extent and surrounded by lamellar bone. However, around the upper, nonthreaded parts of the implants, much of the bone had been resorbed. In this region, fibrous connective tissue was in close contact with the titanium surface. Epithelial proliferation with pocket formation could not be observed in any of the implants. The histomorphometric evaluation of bone-implant contact in threads demonstrated a mean of approximately 51% of the available surface and a mean bone volume of approximately 52%, with a tendency toward greater contact and volume around the implants in the maxilla. If the nonthreaded cylindric portions of the implants were included, mean bone-implant contact was 46% and mean bone volume was 47%.     

Clinical and histologic findings for microimplants placed in one stage and loaded for three months: a case report

Background: Implants are placed in either one or two stages. There is an absence of histologic human evidence relating to implant integration after loading. Purpose: The purpose of this case report was to present clinical and histologic findings for smooth‐surfaced titanium turned microimplants placed in one stage and loaded after healing. Materials and Methods: Five one‐piece microimplants were placed in a fully edentulous mandible. Three microimplants (tests) were placed in one stage and extended through the keratinized mucosa for 3 mm. Two additional microimplants (controls) were placed even with the mucosa. After 3 months of healing, three test implants were loaded for an additional 3 months. At this time, three loaded implants and one control were removed en bloc. Results: Histologic and histometric evaluations were made. For all specimens, there was excellent bone‐to‐implant contact. The loaded implants had from two to four exposed threads. Using marginal bone levels as the reference, the highest percentage of bone‐to‐implant contact was noted with the unloaded control implant (92.2%). One nonaxially loaded implant had 66.9% bone‐to‐implant contact, whereas the axially loaded implants (n = 2) had 77.8% bone‐to‐implant contact. Conclusions: Within the limits of this case report, smooth‐surfaced, titanium threaded microimplants placed in one stage and loaded for 3 months demonstrated excellent osseointegration, with varying bone‐to‐implant contact. The amount of bone‐to‐implant contact may be related to axial implant loading.     

Comparison of chemically and pharmaceutically modified titanium and zirconia implant surfaces in dentistry: a study in sheep

Advanced surface modifications and materials were tested on the same implant geometry. Six types of dental implants were tested for osseointegration after 2, 4 and 8 weeks in a sheep pelvis model. Four titanium implant types were treated with newly developed surface modifications, of which two were chemically and two were pharmacologically modified. One implant was made of zirconia. A sandblasted and acid-etched titanium surface was used as reference. The chemically modified implants were plasma-anodized or coated with calcium phosphate. The pharmacological coatings contained either bisphosphonate or collagen type I with chondroitin sulphate. The implants were evaluated using macroscopic, radiographic and histomorphometric methods. All implants were well osseointegrated at the time of death. All titanium implants had similar bone implant contact (BIC) at 2 weeks (57-61%); only zirconia was better (77%). The main BIC increase was between 2 and 4 weeks. The pharmacologically coated implants (78-79%) and the calcium phosphate coating (83%) showed similar results compared with the reference implant (80%) at 8 weeks. There were no significant differences in BIC. Compared with previous studies the results of all implants were comparatively good.     

Bioactive glass and calcium carbonate granules as filler material around titanium and bioactive glass implants in the medullar space of the rabbit tibia

The effect of bioactive glass (BG) and calcium carbonate (CC) granules on bone formation around titanium and BG implants projecting into the medullary space of rabbit tibia was studied. The bone marrow tissue was removed and the medullary space was filled either with BG or CC (Biocoral®) granules (0 630μ800 –m). Conical titanium and BG implants were inserted into the holes drilled in compact bone using the press fit technique. Histomorphometry was used to measure the bone‐biomaterial area in a 1.O mm wide zone around the head of the implant and the contact between formed bone and implant. Significantly larger bone-biomaterial area was obtained around titanium implants using BG than CC granules while no difference was found in connection of BG implants. Better bone‐implant contact was achieved with BG implants than with titanium implants regardless of the type of granules used. The results indicate that BG may prove to be useful as filler and coating material in connection of implants projecting into bone cavities.     

Long-lasting osseointegration of immediately loaded, bar-connected TPS screws after 12 years of function: a histologic case report of a 95-year-old patient.

The present case report provides histologic findings on four titanium plasma-sprayed screw implants after 12 years of incorporation and functional load in a 95-year-old patient. At the time of implant placement, the four implants were immediately connected with a bar and functionally loaded with a bar-supported overdenture. The histologic analysis demonstrated excellent osseointegration in either cortical or cancellous bone for all implants. The histomorphometric analysis showed direct bone-implant contact of approximately 70% to 80% at the interface. Close to the implant surface, signs of ongoing bone remodeling activities were present. The present histologic case report confirms the validity of the applied treatment concept--to immediately load titanium implants with a titanium plasma-sprayed surface in the anterior region of the mandible--if a minimum of four implants can be inserted and if the four implants are splinted with a bar.     

钛膜和胶原膜联合应用引导种植体周骨缺损骨再生的临床研究

目的：评价钛膜与胶原膜联合应用引导种植体骨缺损骨再生的临床效果。方法：将34颗种植体植入30例患者的狭窄形牙槽嵴或唇颊骨壁缺损拔牙窝,所有种植体的唇、颊侧面部分暴露,种植体周骨缺损空间维持能力较差。测量种植暴露部分的最大长度,将羟基磷灰石珊瑚骨粉置于骨缺损处,采用钛膜覆盖稳定骨移植材料,然后将胶原膜覆盖于钛膜表面,无张力缝合伤口,术后6个月行Ⅱ期手术,取下钛膜,检查骨缺损骨再生的状况,再次测量种植暴露部分的最大长度。结果：2例患者于手术3个月左右因钛膜局部暴露,将钛膜取出。钛膜暴露率为6.6%。术后6个月Ⅱ期手术时见,所有种植体暴露部分完全被再生骨覆盖,种植体暴露部分长度为0。结论：在空间维持能力较差的骨缺损处,钛膜和胶原膜联合应用引导骨再生可获得理想结果。钛膜和胶原膜联合应用可显著降低钛膜的暴露率,延迟发生膜暴露的时间,从而使引导骨再生的结果更加具有可预测性。     

Influence of nicotine administration on different implant surfaces: a histometric study in rabbits

BACKGROUND: This study investigated the influence of implant surface on osseointegration around titanium implants inserted in the tibiae of rabbits administered with nicotine. METHODS: Thirty-two (32) New Zealand rabbits were included in the study. After anesthesia, the tibia surface was exposed and 2 screw-shaped commercially available pure titanium implants 7.0 mm in length and 3.75 mm in diameter were placed bilaterally. A total of 128 implants were inserted: 64 blasted with Al2O3 particles (Group 1) and 64 with a machined surface finish (Group 2). The animals were randomly assigned to 1 of 4 treatment subgroups, and daily subcutaneous injections of nicotine were administered: A) saline solution; B) 0.37 mg/kg; C) 0.57 mg/kg; and D) 0.93 mg/kg. In order to label regenerated bone, a 2% calcein green solution was administered by intramuscular injection at 0, 7, and 15 days after implant insertion. After 42 days, the animals were sacrificed and undecalcified sections were prepared. The degree of bone contact with the implant surface, the bone area, and the intensity of bone labeling were measured into the limits of the implant threads. RESULTS: Statistical analysis (2-way ANOVA) revealed no significant difference regarding the effect of nicotine on bone healing around the implants (P>0.05). However, a significant influence of the implant surface on the degree of bone-to-implant contact was detected in groups C (30.13 +/- 4.97 and 37.85 +/- 8.85, for machined and Al2O3-blasted surfaces, respectively) and D (27.79 +/- 3.93 and 33.13 +/- 8.87, for machined and Al2O3-blasted surfaces, respectively) (P<0.05). CONCLUSIONS: Although nicotine administration may not statistically influence bone healing around titanium implants, implant surface design may enhance osseointegration after nicotine administration.     

Quantitative study on the interface between bone tissue and Blade-vent implants using the image processing system

Undecalcified histopathologic sections of two titanium blade-vent implants (which had survived for five years in a dog) were made, and image analyses of the bone-implant interface were determined. One implant was inserted conventionally in the right mandible, and the other was inserted shallower than usual in the left mandible, so that the shoulder was located at the same level as the residual bone ridge. Using an image analysis technique, we observed, on the deeper implant, a 0-56% rate of bony contact around the implant and a 71-84% rate of bone-vent occupancy in the vents. With the shallower implant, a 0-46% rate of bony contact and a 26-60% rate of bone-vent occupancy were observed. When the two implants were compared, the deeper implant showed relatively higher bony contact and bone-vent occupancy than its less-submerged control in the five-year study.     

Increased bone contact to a calcium-incorporated oxidized commercially pure titanium implant: an in-vivo study in rabbits

The aim of this study was to evaluate the bone response to an oxidized titanium implant (Ox) and a calcium-incorporated oxidized titanium implant (Ca). A blasted titanium implant (Bl) was used as control. The implants were topographically characterized using an optical interferometer and placed: one in each distal femoral metaphysis and two in each proximal tibial metaphysis in rabbits. The rabbits were killed 12 weeks after implant insertion, and the implants and their surrounding tissues were removed en bloc for histomorphometrical evaluations. Topographical evaluation revealed three different surfaces: average height deviation (S(a), microm) values for Ca:Ox:Bl implants were 0.3:0.6:0.9, developed surface area ratios (%) 17:44:31, number of summits per microm(2) 208:136:118, and core fluid retention index values 1.33:1.33:1.38. The mean percentages of bone contact to the implants placed in the tibia (Ca:Ox:Bl) were 47:30:34 and to the implants placed in the femur (Ca:Ox) 32:20. The mean percentages of surrounding bone area for the implants placed in the tibia were 40:47:37 and for the implants placed in the femur 43:46. A significant increase in bone contact was found for smooth (S(a) <0.5 microm) but more densely peaked calcium-incorporated oxidized implants when compared to slightly rougher (S(a)=0.5-1.0 microm) oxidized or blasted implants.     

Biomechanical and histological behavior of zirconia implants: an experiment in the rat

Objective: This study aimed at evaluating the integration of zirconia implants in a rat femur model.
Material and methods: Zirconia implants with two distinct surface topographies were compared with titanium implants with similar topographies. Titanium and zirconia implants were placed into the femurs of 42 male Sprague–Dawley rats. Four groups of implants were utilized: machined zirconia implants, zirconia implants with a rough surface, machined titanium implants, and titanium implants with an electrochemically roughened surface. After a healing period of 28 days, the load-bearing capacity between the bone and the implant surface was evaluated by a push-in test. Additionally, after a healing period of 14 and 28 days, respectively, bone tissue specimens containing the implants were processed and histologically analyzed.
Results: The mean mineralized bone-to-implant contact showed the highest values after 14 and 28 days for the rough surfaces (titanium: 36%/45%; zirconia: 45%/59%). Also, the push-in test showed higher values for the textured implant surfaces, with no statistical significance between titanium (34 N) and zirconia (45.8 N).
Conclusions: Within the limits of the animal investigation presented, it was concluded that all tested zirconia and titanium implant surfaces were biocompatible and osseoconductive. The presented surface modification of zirconia implants showed no difference regarding the histological and biomechanical results compared with an established electrochemically modified titanium implant surface.     

Comparison of zirconia and titanium implants after a short healing period. A pilot study in minipigs

The aim of this animal study was to investigate and compare the osseointegration of zirconia and titanium dental implants. 14 one-piece zirconia implants and 7 titanium implants were inserted into the mandibles of 7 minipigs. The zirconia implants were alternately placed submerged and non-submerged. To enable submerged healing, the supraosseous part was removed, using a diamond saw. The titanium implants were all placed submerged. After a healing period of 4 weeks, a histological analysis of the soft and hard tissue and a histomorphometric analysis of the bone–implant contact (BIC) and relative peri-implant bone-volume density (rBVD; relation to bone-volume density of the host bone) was performed. Two zirconia implants were found to be loose. All other implants were available for evaluation. For submerged zirconia and titanium implants, the implant surface showed an intimate connection to the neighbouring bone, with both types achieving a BIC of 53%. For the non-submerged zirconia implants, some crestal epithelial downgrowth could be detected, with a resultant BIC of 48%. Highest rBVD values were found for submerged zirconia (80%), followed by titanium (74%) and non-submerged zirconia (63%). The results suggest that unloaded zirconia and titanium implants osseointegrate comparably, within the healing period studied.     

A histologic and histomorphometric evaluation of two types of retrieved human titanium implants

This study analyzed the interfacial human bone response to retrieved implants that had been functionally loaded in the human environment. A solid-screw titanium plasma-sprayed (TPS) implant was removed 5 years after implantation because of a fracture at the joint between the implant and the crown. A sand-blasted acid-etched titanium implant (SLA) was used as an anchorage for orthodontic treatment. At the end of the treatment, the SLA implant was removed. Both types were functionally loaded without any symptoms expressed by the patients. Histology showed bone contact between the TPS or the SLA implant and surrounding bone, but the SLA implant revealed much more interfacial bone contact. The contact microradiograms showed that the bone surrounding the TPS and SLA implants was highly calcified. The measured percentage of bone-implant contact around the SLA implant was significantly higher (P <.05) than that around the TPS implant.     

Structure of the bone‐titanium interface in retrieved clinical oral implants

7 clinically stable, "osseointegrated", titanium implants, inserted in human jaws for l–16 years, were retrieved for morphological analysis of the bone‐titanium interface, using 3 different preparation techniques. The bone‐titanium interface varied as judged from light microscopy of ground sections. The threads of the implants were well filled 79–95% with dense lamellar bone as quantified with morphometry. A large fraction of the implant surface (56–85%) appeared to be in direct contact with the mineralized bone. In general, the non‐boric areas consisted of pockets with osteocytes, bone marrow tissue and/or vessels. Sections were prepared for light microscopy and transmission electron microscopy using a fracture technique. where the implant was separated from the embedded tissue before sectioning, and an electropolishing technique, where the bulk part of the implant was electrochemically removed. In areas judged as direct mineralized bone‐titanium contact in the light microscope. the interfacial structure varied at the ultrastructural level. In areas along the interface, unmineralized tissue was present either as a narrow 0.5–l μm wide zone containing collagen fibril or as deeper pockets containing osteocytes or vessels. In areas with mineralized bone contact. an amorphous granular layer (100–400 nm wide) with no mineral was observed in the innermost interface bordering the mineralized bone, with an electron‐dense lamina limitans‐like line (approximately 50 nm thick). It is concluded that the bone‐titanium interface of the 7 clinically retrieved titanium oral implants examined in the present study bone was heterogenous. In areas of a direct mineralized bone‐titanium contact at the ultrastructural level. mineralized bone reached close to the implant surface, but was separated by an amorphous layer. 1 being 100–400 nm thick.     

Effect of hydroxyapatite on bone formation around exposed heads of titanium implants in rabbits

Dense hydroxyapatite (HA)--collagen was placed around the protruding heads of titanium and titanium alloy implants in the femurs of 38 rabbits. After 6 months, bone apposition was evaluated by gross examination and scanning electron microscopy. Although bone was observed in direct contact with the implant heads, the extremities of the implant heads were surrounded by connective tissue. Compared with the control animals, packing dense HA-collagen around the implant heads did not increase the area of osteogenesis. When the implants penetrated into bone through previously placed HA-collagen blocks, there was a decrease in the amount of bone attached to the body of the implants compared with the controls. The results of this study suggest that the use of dense HA does not increase the amount of bone tissue formed around titanium implants.     

Dual-etched implants loaded after 1- and 2-month healing periods: a histologic comparison in baboons

The purpose of this study was to evaluate the effect of early loading of Osseotite dual acid-etched commercially pure titanium dental implants in an established baboon model. Implant sites were prepared by removal of premolars and first molars at maxillary and mandibular sites in 10 adult female baboons (Papio anubis). The resultant edentulous ridges were allowed to heal for 6 weeks. Following the placement of 80 implants, 2-mm healing abutments were placed on each implant and protruded through the mucosa after flap closure. Each implant was functionally loaded with a single crown after either 1 month (n = 40) or 2 months (n = 40) of implant healing. All implants were removed in block section after 3 months of functional loading and prepared for histologic evaluation. Photographs of histologic slides were digitized for data collection. The amount of osseous tissue contact along the implant surface in the buccolingual plane was determined using image analysis. The fraction of direct bone-tissue contact along a standardized region of each implant perimeter was calculated and compared using analysis of variance. Implants loaded after 1 month of healing had a mean of 76.6% + 14.4% bone contact, and implants loaded after 2 months of healing had a mean of 77.2% +/- 12.2% bone contact. Statistically, the 1- and 2-month groups were similar (P = .81). No implant failures were observed in either treatment group. Reducing the surgical healing time from 2 months to 1 month did not statistically affect the amount of bone observed at the tissue-implant interface in baboons under functionally loaded conditions.