Maxillary sinus augmentation using deproteinized bovine bone (Bio-Oss) and Impladent Dental Implant System. Part I. Comparison between one-stage and two-stage procedure

This study was undertaken to compare implant survival after one- or two-stage sinus augmentation. Ninety-two maxillary sinuses in 77 patients were augmented with deproteinized bovine bone (Bio-Oss). These sinuses were sub-divided into two groups: Group 1 (n = 49) was operated on with a one-stage procedure, and Group 2 (n = 43) with a two-stage operation. A hundred and eighty-five implants were inserted in these augmented sinuses. Clinical and radiographical evaluations were performed and recorded according to certain criteria. The follow-up period was ranging from 16 to 44 months. Out of the implants inserted using the one-stage procedure, all survived. Two implants failed in the two-stage procedure group (98.91% implant survival). This study showed that no statistically significance was observed between the two surgical techniques (P < 0.05). Therefore, the authors concluded the type of surgical procedure (one- or two-stage) has no effect on implant survival.     

Evaluation of the success of beta-tricalciumphosphate and deproteinized bovine bone in maxillary sinus augmentation using histomorphometry: a review

Sinus lift operations have become a prerequisite for implantologists in the rehabilitation of atrophic posterior maxilla. Alloplasts and xenografts are the recent innovation in the world of grafting materials and have evolved in such a way as to compensate the need for autografts to be used in conjunction. In order to perfect the grafting materials, histomorphometry is the most often tool used to study the success of the augmentation. This article has tried to commemorate the importance of histomorphometry in maxillary antroplasty and also the success rate of beta-tricalciumphosphate and deproteinized bovine bone as an augmentation material in maxillary augmentation.     

Maxillary sinus augmentation with Bio-Oss particles: a light, scanning, and transmission electron microscopy study in man

Biological interactions occurring at the bone-biomaterial interface are critical for long-term clinical success. Bio-Oss is a deproteinized, sterilized bovine bone that has been extensively used in bone regeneration procedures. The aim of the present study was a comparative light, scanning, and electron microscopy evaluation of the interface between Bio-Oss and bone in specimens retrieved after sinus augmentation procedures. Under light microscopy, most of the particles were surrounded by newly formed bone, while in a few cases, at the interface of some particles it was possible to observe marrow spaces and biological fluids. Under scanning electron microscopy, in most cases, the particle perimeter appeared lined by bone that was tightly adherent to the biomaterial surface. Transmission electron microscopy showed that the bone tissue around the biomaterial showed all the phases of the bone healing process. In some areas, randomly organized collagen fibers were present, while in other areas, newly formed compact bone was present. In the first bone lamella collagen fibers contacting the Bio-Oss surface were oriented at 243.73 +/- 7.12 degrees (mean +/- SD), while in the rest of the lamella they were oriented at 288.05 +/- 4.86 degrees (mean +/- SD) with a statistically significant difference of 44.32 degrees (p < 0.001). In the same areas the intensity of gray value was 172.56 +/- 18.15 (mean +/- SD) near the biomaterial surface and 158.71 +/- 21.95 (mean +/- SD) in the other part of the lamella with an unstatistically significant difference of 13.79 (p = 0.071). At the bone-biomaterial interface there was also an electron-dense layer similar to cement lines. This layer had a variable morphology being, in some areas, a thin line, and in other areas, a thick irregular band. The analyses showed that Bio-Oss particles do not interfere with the normal osseous healing process after sinus lift procedures and promote new bone formation. In conclusion, this study serves as a better understanding of the morphologic characteristics of Bio-Oss and its interaction with the surrounding tissues.     

Development of dental implant movement (IM) checker for dental implant mobility assessment.

This study aimed at developing a dental implant movement (IM) checker for assessing quantitative dental implant mobility. The design of the instrument was based on the tooth mobility (TM) tester, which was previously developed by our group. The IM checker consists of a newly developed measuring probe which has the size of a typical dental drill so that it would be easy to measure at all regions of dental implants. The probe has a bimorph ceramics transducer for actuating an implant at constant frequency and force amplitude and for detecting acceleration response. A set of strain gauges were attached to the bimorph ceramics for detecting preload during measurement. A new digital data acquisition system was used to eliminate measurement artifacts mainly due to probe handling. The IM checker could discriminate the artificial dental implant models in the range of clinical tooth mobility M0 with variation less than 6%. The measuring time needed by five operators was less than 15 s. Accordingly, the IM checker has sufficient measuring reliability and therefore it could be introduced in dental clinics.     

Engineering of bone using porous calcium phosphate cement and bone marrow stromal cells for maxillary sinus augmentation with simultaneous implant placement in goats

The aim of this study was to explore the effects of maxillary sinus floor elevation and simultaneous dental implantation with a tissue-engineered bone complex of calcium phosphate cement (CPC) scaffolds combined with bone marrow stromal cells (BMSCs). A large animal goat model is used with the tissue engineering method. Eighteen bilateral maxillary sinus of nine goats were randomly allocated into three groups; the CPC/BMSC complex (n=6) was used to elevate maxillary sinus floor with a simultaneous implant placement; the effects were compared with those treated with CPC alone (n=6) or autogenous bone (n=6). After a healing period of 3 months, sequential triad-color fluorescence labeling, micro-CT, as well as histological and histomorphometric analyses indicated that the tissue-engineered BMSC/CPC complex could promote earlier bone formation and mineralization, and maximally maintain the volume and height of the augmented maxillary sinus. By comparison, CPC-alone or autogenous bone achieved less bone formation and later mineralization. Besides, the average bone-implant contact value reflecting the osseointegration was 35.63%±9.42% in the BMSCs/CPC group, significantly higher than 22.47%±4.28% in the CPC-alone group or 28.26%±8.03% in the autogenous bone group. In conclusion, CPC serves as a potential substrate for BMSCs for the maxillary sinus floor augmentation and simultaneous implantation. The tissue-engineered bone might enhance the stability of implants and thus be of great significance to achieve improved quality to restore the oral function in clinic.     

上颌窦内外提升不植骨替代材料同期种植牙：随访周围骨量及稳定性的变化

背景：研究已经证实,上颌窦黏膜具有促进成骨的能力,上颌窦内膜与种植体之间的空间随着时间的延长会有新生骨的形成。 目的：通过对两种上颌窦提升术不植骨同期种植牙的研究,明确不植骨对两种上颌窦提升后种植体成活状态的影响。 方法：将上颌后牙区骨量不足的50例患者随机分成上颌窦外提升和上颌窦内提升两组,分别在不植入骨替代材料的情况下同期进行种植体的植入,共植入种植体60个,外提升组25个植体,内提升组35个植体。 结果与结论：在不植骨的情况下,60个种植体经过12个月的观察,59个植体正常行使功能,1例外提升的种植体术后松动,治疗失败。内提升组手术时间和出血量均显著少于外提升组(P < 0.05)。两组患者的近期稳定性(术后12个月)比较差异无显著性意义(P > 0.05)。术后12个月外提升组种植体周围的骨量增加显著少于内提升组(P < 0.05)。结果说明不植骨在上颌窦的两种提升术中是可行的,而且能简化手术过程,减少治疗费用,但对种植体长期稳定性的影响有待进一步观察。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

The effect of alendronate (Fosamax) and implant surface on bone integration and remodeling in a canine model.

Patients at high risk for osteoporosis and its associated morbidity, including postmenopausal women, are being pharmacologically managed to stabilize and improve bone mass. Alendronate sodium (Fosamax) is a commonly used antiresorptive agent effective in osteopenic women for reducing bone resorption, increasing bone density, and decreasing fracture incidence. With the increased incidence of alendronate-treated women who are undergoing hip replacement or fracture repair by prosthesis placement, data are needed to predict how alendronate affects host bone integration with uncemented surfaces. The aim of this study was to determine the effect of alendronate on new bone formation and attachment to implant surfaces in a normal and simulated estrogen-deficient, calcium-deficient canine model, using an implantable bone growth chamber. Alendronate did not affect host bone integration to surfaces commonly used in uncemented total joint arthroplasty, but there were significant differences dependent solely on the type of surface.     

Characterization and biocompatibility of a titanium dental implant with a laser irradiated and dual-acid etched surface

The biological properties of commercial pure titanium (cp-Ti) dental implants can be improved by surface treatment. In this study, the cp-Ti surfaces were prepared to enable machined surfaces (TM) to be compared to the machined, sandblasted, laser irradiated and dual-acid etched surfaces (TA). The surface elements and roughness were characterized. The biocompatibility was evaluated by cell and organ culture in vitro. The removal torque was measured in rabbit implantation. Surface characterization revealed that TA surface was more oxidized than TM surface. The TA surface had micrometric, beehive-like coarse concaves. The average roughness (2.28 mum) was larger than that typical of acid-etched surfaces. Extracts of both materials were not cytotoxic to bone cells. The morphology of cells attached on the TA surface was superior to that on the TM surface. TA promoted cell migration and repaired damaged bones more effectively in organ culture. The formation of bone-like nodules on TA disk exceeded that on TM disk. Rabbit tibia implantation also proved that TA implant had greater removal torque value. These results suggested that TA had good osteoconductivity and was a potential material for dental implantation.     

Metal binding by pharmaceuticals. Part 1. Copper(II) and zinc(II) interactions following ethambutol administration

Formation constants for copper(II) and zinc(II) complexes of dextro-2,2-(ethylenediimino)-di-1-butanol (ethambutol) and its metabolic oxidation product, 2,2-(ethylenediimino)-dibutyric acid (EDBA) have been measured potentiometrically at 37°C, I=0.15 mol dm^–3 [NaCl]. The constants are used in computer models to assess the extent of the formation of these complexes in vivo. These simulations indicate that whereas ethambutol forms metal complexes only to a limited extent in vivo, EDBA competes effectively under physiological conditions for copper(II) and zinc(II). This study suggests that zinc(II) binding by EDBA may account for a number of side effects of ethambutol treatment.To whom correspondence should be sent.     

In vitro investigation of titanium and hydroxyapatite dental implant surfaces using a rat bone marrow stromal cell culture system

In this study, rat bone marrow cells (RBM) were used to evaluate different titanium and hydroxyapatite dental implant surfaces. The implant surfaces investigated were: a titanium surface having a porous titanium plasma-sprayed coating (sample code Ti-TPS), a titanium surface with a deep profile structure (sample code Ti-DPS), an uncoated titanium substrate with a machined surface (sample code Ti-ma) and a machined titanium substrate with a porous hydroxyapatite plasma-sprayed coating (sample code Ti-HA). RBM cells were cultured on the disc-shaped test substrates for 14 days. The culture medium was changed daily and examined for calcium and phosphate concentrations. After 14 days specimens were examined by light microscopy, scanning electron microscopy, energy dispersive X-ray analysis and morphometry of the cell-covered substrate surface. All test substrates facilitated RBM growth of extracellular matrix formation. Ti-DPS and Ti-TPS to the highest degree, followed by Ti-ma and Ti-HA. Ti-DPS and Ti-TPS displayed the highest cell density and thus seem to be well suited for the endosseous portion of dental implants. RBM cells cultured on Ti-HA showed a delayed growth pattern. This may be related to its high phosphate ion release.     

Enhanced bioactivity of a poly(propylene fumarate) bone graft substitute by augmentation with nano-hydroxyapatite

The bioactivity of a nano-hydroxyapatite-augmented, bioresorbable bone graft substitute made from the unsaturated polyester, poly(propylene fumarate), was analyzed by evaluating biocompatibility and osteointegration of implants placed into a rat tibial defect. Three groups of eight animals each were evaluated by grouting bone graft substitutes into 3-mm holes that were made into the anteromedial tibial metaphysis of rats. Thus, a total of 24 animals was included in this study. Two different formulations varying as to the type of hydroxyapatite were used: Group 1 - nano-hydroxyapatite, Group 2 - micron-hydroxyapatite, with a Group 3 control defect remaining unfilled. Animals of each of the three groups were sacrificed in groups of eight at postoperative week three. Histologic analysis revealed best superior biocompatibility and osteointegration of bone graft substitutes when nanohydroxyapatite was employed. At three weeks, there was more reactive new bone formation in this group when compared to the micron-hydroxyapatite group. The control group showed incomplete closure of the defect. This study suggested that nano-hydroxyapatite may improve upon the bioactivity of bone implant and repair materials. The model scaffold used in this study, poly(propylene fumarate), appeared to provide an osteoconductive pathway by which bone will grow in faster. Clinical implications of the use potential advantages of nano-hydroxyapatite on bone repair and orthopaedic implant design are discussed.     

A preliminary study of the dental implant therapy--initial osteogenesis of human mesenchymal stem (HMS0014) cells on titanium discs with different surface modifications

HMS0014 cells were GBR-engineered to proliferate and differentiate into mature osteoblast(Ob)-like cells, which initiated hard tissue matrix deposition in both monolayer and PuraMatrix 3-D cultures. Subsequently, the osteogenesis initiated with attachment/adhesion of HMS0014 cells on either Titanium (Ti) or Ti alloy discs modified with osteoconductive/ osteoinductive surface textures/substrates (e.g., Disc-AO, Disc-HA, Disc-SPI) was histologically assessed. The results obtained were as follows: 1) The HMS0014 cells actively proliferated and differentiated into mature Obs to initiate mineralisation of the ECM since day 1 in both monolayer and 3-D cultures; mineralization was prominently progressed between day 7 and day 14 of cultures. 2) The SEM of 60-minute(min)s specimens demonstrated a loose distribution of proliferating spherical-to-polygonal (10 to 40 microm in diameter, avg.) cells with a bulging cell body sending out many minute filopodia and some lamellipodia to attach with the substrate in the concavities. 3) In the 180-min specimens, the cultured HMS0014 cells actively proliferated and spread into flat, large polygonal cells with prominent lamellipodia and dendritic filopodia (30 microm x 90 microm to 100 microm x 200 microm, approx.) to employ cell-to-substrate and intercellular attachments. 4) On the other hand, the present immunohistochemistry of the attached HMS0014 cells demonstrated the co-expression of F-actin (actin filaments of the cytoskeleton) and CD51 (aV integrin) in both the 60-min and 180-min specimens. We concluded that the present GBR method enhanced HMS0014 cells to initiate an osteogenesis process with a direct bone-to-substratum contact on Ti discs which were subject to different surface modifications.     

Evaluation of a prereduced anaerobically sterilized medium (PRAS II) system for identification anaerobic microorganisms.

A prereduced, anaerobically sterilized system of tubed media (PRAS II; Scott Laboratories, Fiskeville, R.I.) was evaluated for accuracy in the identification of anerobic microorganisms. PRAS II was found to be a rapid and accurate identification system for obligate anaerobes which does not require the use of gas cannula inoculation or incubation in a special anaerobic environment.     

Characterization of implant materials in fetal bovine serum and sodium sulfate by electrochemical impedance spectroscopy. II. Coarsely sandblasted samples

Electrochemical impedance spectroscopy is used to investigate the corrosion resistance of coarsely sandblasted implant alloys, commercially pure titanium, Ti6Al4V, Ti6Al7Nb, and CoCrMo in 0.1M sodium sulfate and fetal bovine serum. Coarsely sandblasted samples have a heterogeneous surface constituted by a large number of protrusions and recessions. Impedance spectra collected in sodium sulfate present two time constants (maxima in the phase-angle of the bode plot) associated with the total surface and with the tips, respectively. In bovine serum, the two maxima in the impedance spectra cannot be distinguished because of the formation of an adsorption layer of organic molecules, which causes a decrease in the values of both the total and tips' capacitances as well as an increase in the polarization resistance. Ti6Al4V and Ti6Al7Nb show the highest corrosion rate both in serum and in sodium sulfate. Based on the capacitance values obtained in sodium sulfate, the real surface area of the coarsely sandblasted electrodes has been estimated relative to mechanically polished surfaces. The values of the effective electrode area correlate with the mechanical properties of the samples: in fact, the softest electrode (commercially pure titanium) shows the largest effective electrode area, whereas the hardest material (CoCrMo alloy) shows the smallest surface area.     

Metal binding by pharmaceuticals. Part 5. Interaction of Cd(II), Ni(II) and Pb(II) with the intracellular hydrolysis products of the anti-tumour agent ICRF 159 and its inactive homologue ICRF 192

Formation constants for the cadmium(II), nickel(II) and lead(II) complexes ofdl-NN-dicarboxamidomethyl-NN-dicarboxymethyl-1,2-diaminopropane (ICRF 198) and the 1,2-diaminobutane homologue (ICRF 226) have been measured potentiometrically at 37°C andI=150 mmol dm^–3 [NaCl]. In all titrations a competing ligand, known to complex strongly with the metal ion, and having its formation constants predetermined, was employed.The constants are used in computer simulation models to assess the relative efficacy of the agents in mobilizing these metals from plasma proteins into low-molecular-weight complexes and the results are compared to those for known chelating agents.It is shown that the lead mobilizing potential of the agents is greater than either EDTA ord-penicillamine; they are, however, less adept in the removal of cadmium and nickel than other established agents.Parts 1–4 are Refs [1–4].     

Preparation of betaTCP/HAP biphasic ceramics with natural bone structure by heating bovine cancellous bone with the addition of (NH(4))(2)HPO(4)

In this study, the calcined bovine bone (CBB)-removing the organic substance by a burning process-with addition of different quantities of ammonium phosphate [(NH(4))(2)HPO(4)] (AP) was heated to a high temperature to transform its crystalline phase constitution from hydroxyapatite (HAP) into a tricalcium phosphate (TCP)/HAP biphasic structure. Results revealed that the CBB without AP appeared to be mainly composed of an HAP type pattern when heated to 1300 degrees C. After adding doped AP to CBB, the HPO(4)(2-) ions of AP condensed into P(2)O(7)(4-) ions at temperatures of 400-600 degrees C. P(2)O(7)(4-) ions reacted with the OH(-) ions of HAP to form betaTCP at temperatures up to 600 degrees C. The conversion reaction of HAP to betaTCP finished at around 900 degrees C. With increasing AP in the CBB, HAP gradually converted into different phase compositions of TCP/HAP or TCP at high temperature. Mechanical testing results showed that there was no significant difference in sintered CBB with different quantities of AP. By heating calcined bovine cancellous bone with different quantities of AP, we obtained different crystalline phase compositions of bioceramics with a natural porous structure.     

Incorporation of perforated and demineralized cortical bone allografts. Part II: A mechanical and histologic evaluation

Laser perforated and partially demineralized cortical bone allografts were orthotopically transplanted into sheep tibiae. This paper reports results of the mechanical testing of the transplanted bones, which was done at nine months postoperatively. Animals were divided into three groups of eight according to the type of cortical allograft used: group 1, no treatment; group 2, laser hole grid; and group 3, laser hole grid and partial demineralization. Thus, changes in flexural rigidity of 24 transplanted whole tibiae were investigated. Starting in the anterior direction at the tibial tuberosity, the flexural rigidity was determined using a nondestructive 4-point bending test. The elliptical distribution of the flexural rigidity was compared to the untreated contralateral control bone of each animal. Mechanical parameters were defined as percentage rates for comparative analysis between groups. Flexural rigidity measurement showed that bones transplanted with untreated allografts were stiffer than contralateral control bones. Partial demineralization of allografts reduced the flexural rigidity of transplanted bones below the level of contralateral control bones. Flexural rigidities of test bones transplanted with laser perforated and partially demineralized allografts were higher than those seen in bones transplanted with partially demineralized allografts. These results were corroborated by the histologic analysis which showed that untreated allografts, although surrounded by a periosteal bone cuff that effectively increased their outer diameter. In contrast, excessive bone resorption was observed in partially demineralized allografts. Laser-perforated and partially demineralized allografts showed histologic evidence of complete incorporation into the host bone. Based on this mechanical evaluation, it was concluded that processing of cortical bone allografts by the combination of perforation and partial demineralization resulted in improved mechanical strength of the transplanted bones as compared to processing by partial demineralization alone.