Comparison of the Effects of Tissue Processing on the Physicochemical Properties of Bone Allografts.

Purpose: To address the hypothesis that the tissue processing methods of solvent dehydration and freeze-drying would differentially affect the physicochemical characteristics of four commercially available bone allografts and the adhesion and differentiation of human bone marrow-derived mesenchymal stromal cells (hBMSCs) on such substrates in vitro. Materials and Methods: The surface morphology, surface area, and elemental composition of four commercially available cancellous bone allografts were examined using SEM, Brunauer-Emmett-Teller (BET) gas adsorption, and inductively coupled plasma (ICP) analyses. SEM was also employed to compare the allograft surfaces to that of human bone exposed by in vitro osteoclastic resorption. The allografts were seeded with hBMSCs, and the number of adhered cells was assessed at 3 and 7 days. Alkaline phosphatase (ALP) activity was quantified as a measure of osteogenic differentiation after 21 days. Results: Marked differences were seen between the physicochemical characteristics of the solvent-dehydrated and freeze-dried allografts, as well as between their resulting bone microarchitectures and that of osteoclast-resorbed human bone. Increased hBMSC adhesion and differentiation were observed on the solvent-dehydrated allografts compared to freeze-dried allografts, which suggests a higher putative osteogenic potential. The latter was attributed to better preservation of the bone collagen microarchitecture integrity, which may provide not only a more complex substrate architecture, but also a more favorable microenvironment to allow nutrients and oxygen to flow to the adhered cells. Conclusion: Commercially available cancellous bone allografts significantly differ in their physicochemical characteristics, stemming from differences in tissue processing and sterilization methods undertaken by tissue banks. These differences impact the response of MSCs in vitro and may alter the biologic performance of the grafts in vivo. Therefore, it is important to consider these characteristics when choosing a bone substitute for clinical application, as the physicochemical properties of the grafts play a crucial role in their interactions with the biologic environment and subsequent incorporation into the native bone.

Early Bone Healing on Hydroxyapatite-Coated and Chemically-Modified Hydrophilic Implant Surfaces in an Ovine Model.

Implant topography affects early peri-implant bone healing by changing the osteoconduction rate in the surrounding biological environment. Implant surfaces have been designed to promote faster and stronger bone formation for rapid and stable prosthesis loading. Early peri-implant bone healing has been observed with a sandblasted, acid-etched implant that was chemically modified to be hydrophilic (cmSLA). The present study investigates whether early peri-implant bone healing extends to a rough surface implant with a high crystalline hydroxyapatite surface (TSV MP-1 HA). Three implants were randomly placed in porous trabecular bone within both medial femoral condyles of 10 sheep. Early peri-implant bone stability was measured at 3- and 6-weeks healing time following implant insertion. Results indicated a similar implant stability quotient between the implants at insertion and over time. The significant increase over time of reverse torque values with respect to insertion torque (p < 0.001) did not differ between the implants. However, the bone-to-implant contact of TSV MP-1 HA was significantly higher than that of cmSLA implants at 6 weeks (p < 0.01). These data validate previous findings of a hydrophilic implant surface and extend the observation of early osseointegration to a rough surface implant in porous trabecular bone.

In vitro assessment of connection strength and stability of internal implant-abutment connections.

BACKGROUND: Various connections have been machined to improve the fit between the dental abutment and implant. In vivo, the instability created by imprecisely fitting components can cause soft tissue irritation and bacterial colonization of the implant system. The aim of this study was to quantify abutment stability under in vitro force applications. METHODS: Abutment stability and fit were quantitatively measured after application of rotational, vertical, and horizontal forces. FINDINGS: The abutment connection held by friction (Friction-Fit) was the only group to have 0° angular rotation. A significantly greater vertical force was required to pull the abutment from the implant for the Friction-Fit connection as compared to all other experimental groups. The abutment connection held by a mechanically locking friction-fit with four grooves (CrossFit) and Friction-Fit demonstrated significantly lower lateral movement as compared to all other connections. The remaining connections evaluated included two hexagon connections that rely on screw placement for abutment fit (Conical + Hex #1 and Conical + Hex #2), one connection with protruding slots to align with recessed channels inside the implant (Conical + 6 Indexing Slots), and an internal connection that allows for abutment indexing every 120° (Internal Tri-Channel). INTERPRETATION: Internal connection geometry influenced the degree of abutment movement. Friction-Fit and CrossFit connections exhibited the lowest rotational and horizontal motions. Significant differences were found between Friction-Fit and CrossFit following the application of a vertical force, with the Friction-Fit requiring a significantly greater pull force to separate the abutment from the implant.

Vitro culture of axe-head glochidia in pink heelsplitter Potamilus alatus and mechanism of its high host specialists.

The basal media M199 or MEM was utilized in the classical method of vitro culture of glochidia where 1-5% CO2 was required to maintain stable physiological pH for completion of non-parasitic metamorphosis. The classical method encounters a great challenge to those glochidia which undergo development of visceral tissue but significantly increase in size during metamorphosis. The improved in vitro culture techniques and classical methods were firstly compared for non-parasitic metamorphosis and development of glochidia in pink heelsplitter. Based on the improved method, the optimal vitro culture media was further selected from 14 plasmas or sera, realizing the non-parasitic metamorphosis of axe-head glochidia for the first time. The results showed that addition of different plasma (serum) had significant effect on glochidial metamorphosis in pink heelsplitter. Only glochidia in the skewband grunt and red drum groups could complete metamorphosis, the metamorphosis rate in skewband grunt was 93.3±3.1% at 24±0.5°C, significantly higher than in marine and desalinated red drum. Heat-inactivated treatment on the plasma of yellow catfish and Barbus capito had significant effect on glochidia survival and shell growth. The metamorphosis rate also varied among different gravid period, and generally decreased with gravid time. Further comparison of free amino acid and fatty acid indicated that the taurine of high concentration was the only amino acid that might promote the rapid growth of glochidial shell, and the lack of adequate DPA and DHA might be an important reason leading to the abnormal foot and visceral development. Combined with our results of artificial selection of host fish, we tentatively established the mechanism of its host specialists in pink heelsplitter for the first time. This is the first report on non-parasite metamorphosis of axe-head glochidia based on our improved vitro culture method, which should provide important reference to fundamental theory research of glochidia metamorphosis and also benefit for better understand of mechanism of host specialists and generalists of Unionidae species.

New bone formation and trabecular bone microarchitecture of highly porous tantalum compared to titanium implant threads: A pilot canine study.

AIM: This study evaluated new bone formation activities and trabecular bone microarchitecture within the highly porous region of Trabecular Metal™ Dental Implants (TM) and between the threads of Tapered Screw-Vent® Dental Implants (TSV) in fresh canine extraction sockets. MATERIALS AND METHODS: Eight partially edentulated dogs received four implants (4.1 mmD × 13 mmL) bilaterally in mandibular fresh extraction sockets (32 TM, 32 TSV implants), and allowed to heal for 2, 4, 8, and 12 weeks. Calcein was administered to label mineralizing bone at 11 and 4 days before euthanasia for dogs undergoing all four healing periods. Biopsies taken at each time interval were examined histologically. Histomorphometric assay was conducted for 64 unstained and 64 stained slides at the region of interest (ROI) (6 mm long × 0.35 mm deep) in the midsections of the implants. Topographical and chemical analyses were also performed. RESULTS: Histomorphometry revealed significantly more new bone in the TM than in the TSV implants at each healing time (p = .0014, .0084, .0218, and .0251). Calcein-labeled data showed more newly mineralized bone in the TM group than in the TSV group at 2, 8, and 12 weeks (p = .045, .028, .002, respectively) but not at 4 weeks (p = .081). Histologically TM implants exhibited more bone growth and dominant new immature woven bone at an earlier time point than TSV implants. The parameters representing trabecular bone microarchitecture corroborated faster new bone formation in the TM implants when compared to the TSV implants. TM exhibited an irregular faceted topography compared to a relatively uniform microtextured surface for TSV. Chemical analysis showed peaks associated with each implant's composition material, and TSV also showed peaks reflecting the elements of the calcium phosphate blasting media. CONCLUSIONS AND CLINICAL IMPLICATIONS: Results suggest that the healing pathway associated with the highly porous midsection of TM dental implant could enable faster and stronger secondary implant stability than conventional osseointegration alone; however, prospective clinical studies are needed to confirm these potential benefits in patients with low bone density, compromised healing, or prior implant failure.

Immediate mechanical stability of threaded and porous implant systems.

BACKGROUND: Primary stability of a dental implant system is an essential factor to maintain its long-term success. Thus, the objective of this study was to examine whether primary stability is different between threaded and porous dental implant systems placed in artificial bone blocks and human cadaveric mandibular bone. MATERIALS AND METHODS: Forty-two threaded and 42 highly porous dental implants were placed in artificial polyurethane bone foams with 7 different thicknesses (3.5 to 12mm). In addition, 11 threaded and 11 porous implants were installed in 8 edentulous mandibles of human cadavers. Implant stability quotient values, insertion torque, static and dynamic stiffness, and viscoelastic tan δ of each implant system were measured. Mean gray values were obtained at the implantation sites in the human mandible. FINDINGS: The porous implant group had substantially lower implant stability quotient values and insertion torque values than the threaded implant group that were equal or >5.5mm in thickness of the artificial bone block (p<0.026) with the exception of 8.5mm thickness, while static and dynamic stiffness values were not different between the two implant groups greater than 5.5mm in thickness (p>0.132). Static and dynamic stiffness values of the porous group were significantly greater than the thread group in the human mandibular bone (p<0.015). INTERPRETATION: The porous layer supports axial loading better than lateral and shear loading of the dental implant system. This result indicates that trabecular shaped architecture of the porous layer may provide sufficient anchorage compromising reduction of the axial primary stability of the porous implant system to be comparable with the threaded implant system.

Population Susceptibility to Insecticides and the Development of Resistance in Bactrocera cucurbitae (Diptera: Tephritidae).

Excessive insecticide applications are commonly used to manage Bactrocera cucurbitae Coquillett in China. Resistance status, resistance development trends, and patterns of cross-resistance to insecticides in B. cucurbitae were investigated. Among 21 populations from Hainan Island, two populations expressed high resistance to beta-cypermethrin; seven, eight, and ten populations expressed intermediate resistance to spinosad, avermectin, and beta-cypermethrin, respectively; four, six, one, five, and four populations expressed low resistance to spinosad, avermectin, trichlorfon, beta-cypermethrin, and fipronil, respectively; and the remaining populations exhibited either minor resistance or remained susceptible. Analysis of the development of resistance showed that resistance levels to spinosad and avermectin were readily developed at 40.68- and 18.42-fold, respectively, and a spinosad-resistant strain also showed relative positive cross-resistance to beta-cypermethrin and avermectin, but relative negative cross-resistance to trichlorfon and fipronil. These data represent the most extensive survey of insecticide resistance conducted in B. cucurbitae to date, and the level of insecticide resistance in populations should be considered when designing control measures and pest management strategies.

Associations of Resonance Frequency Analysis with Dynamic Mechanical Analysis of Dental Implant Systems.

BACKGROUND: Resonance frequency analysis (RFA) has been introduced as a noninvasive method to clinically estimate the stability of dental implant systems. PURPOSE: The objective of this study was to examine whether implant stability quotient (ISQ) values of RFA can account for mechanical stability of the dental implant system, which is assessed using dynamic mechanical analysis (DMA). MATERIALS AND METHODS: Fifty-seven screw-type titanium dental implants were placed in artificial polyurethane foams with seven different thicknesses (3.5 to 12 mm) and eight edentulous mandibles of human cadavers (four men and four women, 79.11 ± 13.48 years). After the ISQ values, insertion torque, and static stiffness of each implant system were measured, the DMA was performed to assess dynamic stiffness and viscoelastic tan δ. RESULTS: The ISQ value had strong positive correlations with thickness, insertion torque, static and dynamic stiffness, and a negative correlation with tan δ of implant systems in artificial bone blocks (r = 0.769 to 0.992, p < .043). However, the ISQ value was correlated with only the insertion torque of implant systems in human mandibles (p < .049). CONCLUSION: The ISQ values could reflect mechanical stability of the dental implant system under the controlled condition of homogeneous density in simple dimensions.

Evaluation of Different Implant Designs in a Ligature-Induced Peri-implantitis Model: A Canine Study.

PURPOSE: Peri-implantitis is a challenging situation that leads to tissue destruction and eventual implant failure. The purpose of this study was to evaluate and compare, clinically and histologically, the influence of ligature-induced peri-implantitis on two implant designs in a canine extraction socket model. MATERIALS AND METHODS: Sixty-four implants (4.1 × 13 mm) were placed bilaterally in eight dogs immediately after extraction of the mandibular premolars (P3, P4) and molars (M1, M2). Thirty-two conventional threaded implants (group A) and 32 tantalum-based porous implants (group B) were placed. After 12 weeks of normal healing, experimental peri-implantitis was induced in four dogs via the placement of ligatures subgingivally around the implant necks in the treatment group; the control group remained ligature-free. Two dogs in each group were euthanized after 12 or 26 weeks of plaque accumulation (control group dogs received regular cleanings). Clinical evaluations were conducted during the observation period and histologic sections were obtained for histologic and histomorphometric assessments. RESULTS: All the implants exhibited clinical and histologic osseointegration. The treatment group showed significant loss of peri-implant tissue from the induced peri-implantitis. Pocket probing depths for the treatment groups were significantly greater than those of the control groups. Mean bone-to-implant-contact values were not statistically different for control vs treatment groups or for group A vs group B. In the treatment group, group B implants exhibited mean bone ingrowth of 28.4% to 36.3% and achieved more bone formation along the length of the implant than group A implants in the treatment group. CONCLUSION: Implant design did not influence the tissue response or histomorphometric findings under induced peri-implantitis in the canine extraction socket.

Outcome after placement of tantalum porous engineered dental implants in fresh extraction sockets: a canine study.

PURPOSE: This study evaluated the stability and histologic proof of osseoincorporation of Trabecular Metal (TM) dental implants, which feature a tantalum-based porous midsection. MATERIALS AND METHODS: A total of 48 TM implants (test group) and Tapered Screw-Vent implants (control group) were immediately placed bilaterally into mandibular extraction sockets in dogs. Resonance frequency analysis was performed at weeks 0, 2, 4, and 12 after implant placement. Histologic and histomorphometric evaluations of the implant interface were performed. RESULTS: Changes in mean implant stability quotients (ISQ) revealed no statistical differences between the test and control groups. Histologic analysis showed bone ingrowth into the porous tantalum structure of all test group implants. Histomorphometric analysis revealed an increased percentage of bone-to-implant contact between 4 and 8 weeks in both test and control groups. The porous sections of the test group exhibited significantly more new bone inside the pores at week 12 in comparison to weeks 2 and 4. No correlation was observed between ISQ and histomorphometric parameters. CONCLUSION: In a canine immediate extraction socket model, both test and control implants demonstrated comparable implant stability and bone-to-implant contact. Bone ingrowth was evident within the tantalum porous section of the test implants during the early healing.

Bone ingrowth and initial stability of titanium and porous tantalum dental implants: a pilot canine study.

PURPOSE: To investigate if a dental implant system with a midsection covered by 3-dimensionally porous tantalum material would exhibit stability comparable with a traditional threaded titanium alloy implant system and whether bone would grow into the porous section. METHODS: Three experimental and 3 control implants were placed in the individual mandibles of 8 dogs. Resonance frequency analysis assessed implant stability at 0, 2, 4, 8, and 12 weeks of healing. Histomorphometric and backscattered scanning electron microscopic analyses examined the presence of bone ingrowth into the experimental implant's porous section and bone-to-implant contact along the titanium surfaces of both implants. RESULTS: Implant stability did not significantly differ during 0 to 12 weeks of healing. Progressive tissue mineralization developed inside porous sections from weeks 2 to 12. Porous implants exhibited a combination of progressive osseointegration along their titanium surfaces and bone ingrowth inside their porous tantalum sections. CONCLUSIONS: Cortical and apical implant threads, combined with the porous section, were able to stabilize the experimental implant to the same degree as the fully threaded control implant.

Age-stage, two-sex life table of Brontispa longissima (Gestro) (Coleoptera: Hispidae) feeding on four palm plant varieties.

The life history of Brontispa longissima (Gestro) (Coleoptera: Hispidae), reared under laboratory conditions on leaves of coconut (Cocos nucifera L.), royal palm [Roystonea regia (Kunth) O.F.Cook], bottle palm [Hyophorbe lagenicaulis (L. Bailey) H.E.Moore], and fishtail palm (Caryota ochlandra Hance) was analyzed using age-stage, two-sex life table. Means and standard errors of population growth parameters were calculated using the jackknife method. Moreover, survival rate and fecundity data were applied to project the population for revealing the different stage structure. The mean intrinsic rates of population growth when reared on each respective leaf type were 0.032, 0.031, 0.019, and 0.044. Individuals reared on C. nucifera achieved the highest net reproduction rate at 114.5 offspring per female. The mean generation times of B. longissima ranged from 93.2 d (reared on C. ochlandrai) to 161.5 d (reared on H. lagenicaulis). Projections from survival rate and fecundity data indicated that B. longissima populations can row considerably faster on C. ochlandra than on the other three host plants. The results validate the two-stage life history approach taken, providing an essential tool for developing and testing future control strategies.

Differential susceptibilities of Brontispa longissima (Coleoptera: Hispidae) to insecticides in Southeast Asia.

To present the susceptibility of Brontispa longissima (Gestro) (Coleoptera: Hispidae) to insecticides, 22 populations were collected in Southeast Asia from 2007 to 2010. Moreover, the laboratory susceptible strain was maintained. The results demonstrated that the lethal concentration50 value of the susceptible strain to avermectin, beta-cypermethrin, and acetamiprid was 0.034, 0.024, and 1.843 mg liter(-1), respectively. Compared with the susceptible strain, 10 populations developed a medium level of resistance to avermectin (10.8-fold < resistance ratio [RR] < 34.7-fold) and 11 populations had low or minor resistance (3.6-fold < RR < 9.6-fold), only one population from Qionghai still remained susceptible (RR = 2.04-fold). The Zhangjiang population expressed high resistance (RR = 46.1-fold), five populations expressed medium resistance (10.6-fold < RR < 18.1-fold), and 12 populations had low resistance (5.36-fold < RR < 9.66-fold) for beta-cypermethrin, only four populations maintained low resistance or susceptibility (2.08-fold < RR< 3.49-fold). All populations were susceptible to acetamiprid (1.65-fold < RR < 2.89-fold), except for the Jakarta population that developed minor resistance (4.33-fold). This study shows that the resistance to beta-cypermethrin and avermectin in B. longissima is widespread. However, most populations remain susceptible to acetamiprid. Acetamiprid may be considered an available option for the control of B. longissima and should be considered when designing pest management programs.

A hybrid coating of biomimetic apatite and osteocalcin.

A novel hybrid coating of biomimetic apatite(BAp) and osteocalcin (OC) was prepared by incubating BAp-coated Ti6A14V coupons in an osteocalcin-containing medium. A significant amount (up to 1.0 wt %) of OC was adsorbed by the BAp coating within 3 h of incubation as demonstrated by high-performance liquid chromatography. Characterizations of the hybrid coating with environmental scanning microscopy and X-ray diffraction indicated that protein adsorption does not alter the microstructure of the coating. The presence of OC in the hybrid coating was visualized with fluorescence microscopy using an immuno-labeling procedure. The affinity of OC to the BAp coating was examined using a 20-h elution test in phosphate-buffered saline and only a minimal amount (<10%) of the loaded OC was eluted out. When the coating was fully dissolved in hydrochloric acid solution after elution, about 78% of the loaded OC could be recovered. Enzyme-linked immunosorbent assay and peptide sodium dodecylsulfate-polyacrylamide gel electrophoresis confirmed the integrity and activity of OC molecules throughout the tests. The preliminary cell culture tests showed a significant effect of OC on the attachment and proliferation of osteoblasts. The quick loading profile and high affinity of OC to the BAp coating make it an ideal candidate for the hybrid coating preparation in clinical environment.