The ARTUS device: the first feasibility study in human cadavers.

INTRODUCTION: The aim was to perform a feasibility study of the new artificial sphincter device ARTUS in human cadavers. ARTUS is a new electro-mechanical device, which may prevent urethral damage due to a new working principle which is to perform only sequential pressure on successive parts of the urethra. MATERIAL AND METHODS: The implantation of the ARTUS device was performed in six cadavers (3 males, 3 females) with different body mass indices. Subsequently the basic operation data (operation time, cuff size, length of wires, complication) were assessed. RESULTS: The implantation of the ARTUS device is performed easily by the same technique which is commonly used for the AMS 800 implantation. The mean operation time was 20 minutes. The mean cuff size was 4.5 cm in male and 6 cm in female cadavers. The average length of the wires was 12 cm. The necessary subcutaneous pouch had to be bigger than the space used for the tubes of the AMS 800 device. The study is limited by its preclinical setting. CONCLUSIONS: Our results demonstrate that this new artificial urinary sphincter device can be easily implanted. The technical and surgical approaches are similar to those which are applied in the case of the AMS 800 device. Therefore experienced surgeons will be able to adapt their technique easily.

Biomechanical evaluation of a microstructured zirconia implant by a removal torque comparison with a standard Ti-SLA implant.

OBJECTIVES: The purpose of this study was to evaluate the biomechanical bone tissue response to novel microstructured zirconia implants in comparison to sandblasted and acid-etched (SLA) titanium implants through the analysis of removal torque (RTQ) measurements. MATERIALS AND METHODS: Ti-SLA implants with a sandblasted, large-grit and acid-etched surface were compared with zirconia implants with an acid-etched surface. All implants had the same shape, a diameter of 4.1 mm and a length of 10 mm. A total of 136 implants were placed in the maxillae of 17 miniature pigs. Six animals were sacrificed after both 4 and 8 weeks and five animals were sacrificed after 12 weeks, thus providing a total of 102 implants for RTQ testing (34 implants were reserved for future histological analysis). The RTQ analysis was successfully performed, using a mixed model regression with P-values calculated using the nonparametric Brunner-Langer method, on 100 of the 102 implants, two were excluded from the analysis. RESULTS: The adjusted mean RTQ values for Ti-SLA implants were 131 Ncm (95% CI: 107-155) at 4 weeks, 128 Ncm (108-148) Ncm at 8 weeks, and 180 Ncm (153-207 Ncm) at 12 weeks of healing, whereas RTQ values for the zirconia implants were 110 Ncm (86-134), 97 Ncm (76-118) and 147 Ncm (121-174) at the corresponding time intervals. A comparison of the implant materials resulted in P-values of P = 0.114 at 4 weeks, P = 0.034 at 8 weeks and P = 0.105 at 12 weeks (significance set at P < 0.05). CONCLUSIONS: Within the limits of the present study, it could be confirmed that the biomechanical bone-tissue response of the investigated zirconia implants is non-inferior to that of the well-documented, roughened titanium surface, at each time point, within the set tolerance. There were no statistically significant differences between the two materials after a healing period of 4 and 12 weeks. The RTQ values of both implant types increased significantly from the 8-week to the 12-week time point.

Influence of frequent clinical probing during the healing phase on healthy peri-implant soft tissue formed at different titanium implant surfaces: a histomorphometrical study in dogs.

OBJECTIVES: To investigate (i) the impact of different titanium implant surfaces on soft tissue integration over 6 months, and (ii) the influence of frequent clinical probing during the healing phase on the established mucosal seal. MATERIAL AND METHODS: Standardized clinical probing was randomly performed (12 dogs, probing versus control) at different transmucosal surfaces [machined (M), sand-blasted/acid-etched (SLA), and chemically modified acid-etched (modA), modSLA] at 2, 4, 8, and 12 weeks (i.e. 1 x , 2 x , 3 x , and 4 x). Histomorphometrical analysis (e.g. mucosal margin (PM) - apical extension of the junctional epithelium (aJE), PM - coronal level of bone-to-implant contact (CBI) was performed at 4, 8, 12, and 24 weeks. RESULTS: While M and SLA groups revealed a split formation, epithelial cells and connective tissue were in close contact to modA and modSLA surfaces. Frequent clinical probing (i.e. 3 x and 4 x) increased mean pocket depths, PM-aJE, and aJE-CBI values in all groups and markedly disrupted the epithelial and connective tissue attachment. CONCLUSIONS: It was concluded that irrespective of the surface characteristics, a frequent clinical probing at short intervals during the healing phase was associated with dimensional and structural changes of the mucosal seal.

Impact of guided bone regeneration and defect dimension on wound healing at chemically modified hydrophilic titanium implant surfaces: an experimental study in dogs.

OBJECTIVES: The aim of the present study was to evaluate the impact of guided bone regeneration and defect dimension on wound healing at chemically modified titanium implant surfaces (modSLA). MATERIALS AND METHODS: ModSLA implants were placed at chronic-type lateral ridge defects of different heights (H1-H4: 2, 4, 6 and 8 mm) and randomly allocated to either (a) GBR (polyethylene glycol membrane + biphasic calcium phosphate) or (b) untreated control. At 2 and 8 weeks (n=6 dogs each), dissected blocks were processed for histomorphometrical analysis [e.g., percentage linear fill (PLF), regenerated area (RA)]. RESULTS: At 8 weeks, both groups revealed comparable mean PLF (%) [ CONTROL: H1 (26.1 +/- 5.8)-H4 (60.4 +/- 11.8); GBR: H1 (8.3 +/- 5.3)-H4 (50.7 +/- 23.1)] and RA (mm(2)) [ CONTROL: H1 (2.5 +/- 0.4)-H4 (7.4 +/- 4.1); GBR: H1 (1.8 +/- 1.0)-H4 (10.8 +/- 5.9)] values. A significant difference was observed for the mean PLF values at H1 defects. CONCLUSION: It was concluded that (i) modSLA titanium implants supported bone regeneration and osseointegration at H1-H4 defects and (ii) the present GBR procedure did not seem to improve the outcome of vertical bone regeneration, but tended to increase the mean RA values.

Surface alterations of polished and sandblasted and acid-etched titanium implants after Er:YAG, carbon dioxide, and diode laser irradiation.

PURPOSE: Laser treatment has become a popular method for resolving peri-implantitis, but the full range of its effects on implant surfaces is unknown. The purpose of the present investigation was to analyze the influence of different clinically applicable erbium:yttrium-aluminum-garnet (Er:YAG), carbon dioxide (CO2), and diode laser parameters on titanium surfaces that were either polished or sandblasted, large-grit, acid-etched (SLA). MATERIALS AND METHODS: Six polished and six SLA titanium disks were irradiated at nine different power settings (n = 54 polished, 54 SLA) with Er:YAG, CO2, or diode lasers. The CO2 and diode lasers were used in continuous wave mode, and the Er:YAG laser was used in a pulsed manner. The surface of each disk was analyzed by scanning electron microscopy and confocal white light microscopy. Each disk was irradiated on six circular areas of 5 mm in diameter with the same specific laser setting for 10 seconds. RESULTS: Within the chosen parameters, the CO2 and diode laser did not cause any visible surface alterations on either the polished or SLA disks. In contrast, both polished and SLA disks showed surface alterations when irradiated with the pulsed Er:YAG laser. The SLA surfaces showed alteration after 10 seconds of irradiation with Er:YAG laser at 300 mJ/10 Hz. The surfaces of the polished disks did not show alteration with the Er:YAG laser until they were irradiated at the higher energy of 500 mJ/10 Hz for 10 seconds. The results of confocal white light microscopy were in agreement with scanning electron micrographs. CONCLUSION: In contrast to continuous-wave diode and CO2 laser irradiation, pulsed Er:YAG laser irradiation caused distinct alterations with power settings beyond 300 mJ/10 Hz on the SLA surface and 500 mJ/10 Hz on the polished surface. Thus, it is only safe to use the Er:YAG laser for implant surface irradiation with settings no higher than 300 or 500 mJ/10 Hz.

Bone response to loaded implants with non-matching implant-abutment diameters in the canine mandible.

BACKGROUND: One way to evaluate various implant restorations is to measure the amount of bone change that occurs at the crestal bone. The objective of this study was to histologically evaluate the alveolar bone change around a bone-level, non-matching implant-abutment diameter configuration that incorporated a horizontal offset and a Morse taper internal connection. METHODS: The study design included extraction of all mandibular premolars and first molars in five canines. After 3 months, 12 dental implants were placed at three levels in each dog: even with the alveolar crest, 1 mm above the alveolar crest, and 1 mm below the alveolar crest. The implants were submerged on one side of the mandible. On the other side, healing abutments were exposed to the oral cavity (non-submerged). Gold crowns were attached 2 months after implant placement. The dogs were sacrificed 6 months postloading, and specimens were processed for histologic and histometric analyses. RESULTS: Evaluation of the specimens indicated that the marginal bone remained near the top of the implants under submerged and non-submerged conditions. The amount of bone change for submerged implants placed even with, 1 mm below, and 1 mm above the alveolar crest was -0.34, -1.29, and 0.04 mm, respectively (negative values indicate bone loss). For non-submerged implants, the respective values were -0.38, -1.13, and 0.19 mm. For submerged and non-submerged implants, there were significant differences in the amount of bone change among the three groups (P <0.05). The percentage of bone-to-implant contact for submerged implants was 73.3%, 71.8%, and 71.5%. For non-submerged implants, the respective numbers were 73.2%, 74.5%, and 76%. No significant differences occurred with regard to the percentage of bone contact. CONCLUSIONS: Minimal histologic bone loss occurred when dental implants with non-matching implant-abutment diameters were placed at the bone crest and were loaded for 6 months in the canine. The bone loss was significantly less (five- to six-fold) than that reported for bone-level implants with matching implant-abutment diameters (butt-joint connections).

The challenges in artificial muscle research to treat incontinence.

Sphincters to guarantee continence are in principal the simplest muscles, because only two states (closed and open) seem to be important. The healthy urinary sphincter, however, provides dynamic components. During the filling phase the increase in tonus prevents urinary loss. The sphincter rapidly responds to pressure pulses caused, for example, by coughing. Contemporary artificial sphincters, however, merely generate two states and often induce atrophy and erosion. Hence the success of commercially available, continually improved implants is still limited. This communication reviews two physical principles, shape memory alloys and electrically activated polymer nanostructures, for applications in artificial sphincters which adapt the pressure acting on the urethra and react to stress situations such as coughing. The application of these principles allows intermittent reduction of pressure on the urethra, thus involving significantly less atrophy. The fabrication of reliably working nanostructures, however, is ambitious and will need time-consuming, high-level engineering.

Bone regeneration in dehiscence-type defects at non-submerged and submerged chemically modified (SLActive) and conventional SLA titanium implants: an immunohistochemical study in dogs.

OBJECTIVES: The aim of the present study was to evaluate bone regeneration in dehiscence-type defects at non-submerged and submerged titanium implants with chemically modified (mod) and conventional sandblasted/acid-etched (SLA) surfaces. MATERIAL AND METHODS: Standardized buccal dehiscence defects were surgically created following implant site preparation in both the upper and lower jaws of 12 beagle dogs. Both types of implants were randomly assigned to either a non-submerged or a submerged healing procedure. After 1, 2, 4, and 8 weeks, dissected blocks were processed for histomorphometrical [e.g. new bone height (NBH), per cent linear fill (PLF), percentage of bone to implant contact (BIC-D), area of new bone fill (BF)] and immunohistochemical analysis. RESULTS: At 8 weeks, non-submerged and submerged SLA implants revealed significantly lower mean NBH (1.1+/-0.8-1.9+/-1.2 mm), PLF (27.7+/-20.3-46.0+/-28.5%), BIC-D (26.8+/-10.4-46.2+/-16.2%), and BF (1.3+/-0.9-3.4+/-2.8 mm(2)) values than respective modSLA implants [NBH (2.6+/-0.8-4.3+/-0.1 mm), PLF (64.2+/-19.4-107.2+/-4.7%), BIC-D (67.5+/-18.8-82.1+/-14.8%), BF (2.9+/-1.0-6.7+/-1.1 mm(2))]. Within modSLA groups, significantly highest BF values were observed at submerged implants. CONCLUSION: It was concluded that (i) modSLA titanium surfaces promoted bone regeneration in acute-type buccal dehiscence defects and (ii) a submerged healing procedure improved the outcome of healing additionally.

Differentiation and cytokine synthesis of human alveolar osteoblasts compared to osteoblast-like cells (MG63) in response to titanium surfaces.

OBJECTIVES: The aim of this study was to investigate the influence of different implant surface topographies and chemistries on the expression of differentiation/proliferation markers on MG63 cells and primary human alveolar osteoblasts. METHODS: Hydrophobic acid-etched (A) and hydrophobic coarse-grit-blasted, acid-etched (SLA) surfaces and hydrophilic acid-etched (modA) and hydrophilic coarse-grit-blasted (modSLA) surfaces were produced. Thereby, modA and modSLA surfaces were rinsed under nitrogen protection and stored in a sealed glass tube containing isotonic NaCl solution at pH 4-6. Tissue culture plates without specimens served as controls. The behavior of MG63 cells and primary human alveolar osteoblasts (AOB) grown on all surfaces was compared through determination of alkaline phosphatase (ALP) activity, cell proliferation ((3)H-thymidin incorporation, MTT colorimetric assay) and expression of osteocalcin (OC), osteoprotegerin (OPG), transforming growth factor-beta1 (TGF-beta(1)) and vascular endothelial growth factor (VEGF), detected with commercial available test kits. RESULTS: Proliferation of MG63 and primary cells was highest on controls, followed by A surfaces, modA and SLA surfaces being almost on the same level and lowest on modSLA surfaces. modSLA surfaces exhibited highest ALP and OC production, followed by SLA, modA and A surfaces. Proliferation and OC production were comparable for MG63 cells and AOB. OPG, TGF-beta(1) and VEGF produced on primary cells showed a slightly different rank order on different surfaces compared to MG63 cells. modSLA still showed the highest production of OPG, TGF-beta(1) and VEGF, but was followed by modA, SLA and A. Statistical significance was checked by ANOVA (p<0.0035). SIGNIFICANCE: MG63 cells and primary human alveolar osteoblasts showed similar proliferation and differentiation characteristics on different titanium surfaces. Only modA surfaces showed enhanced expression of OPG, TGF-beta(1) and VEGF on MG63 cells compared to primary human alveolar osteoblasts. Overall, the lowest proliferation rates and the highest expressions of differentiation markers and growth factor productions were observed on modSLA.

The initial attachment and subsequent behavior regulation of osteoblasts by dental implant surface modification.

The aim of this study was to investigate the influence of hydrophobic acid-etched (A) and coarse-blasted large-grit and acid-etched (SLA) surfaces as well as hydrophilic modified acid-etched (modA) and modified coarse-blasted large-grit and acid-etched (modSLA) surfaces on the behavior of MG63 cells grown on these surfaces through determination of cell attachment and cell proliferation, time-lapse microscopy of fluorescence-labeled cells, and determination of gene expression by reverse transcription-polymerase chain reaction (RT-PCR). No significant difference of cell attachment on various titanium surfaces was found. Increased cell proliferation was observed on the A surface and the SLA surface compared with the modA surface and the modSLA surface. After 2 days of incubation, on modSLA and modA surfaces a tendency of formation of cell clusters has been observed, which was most pronounced on modSLA surface. On the A and the SLA surface, cell cluster formation started after longer incubation periods. The expression level of the bone-associated genes (alkaline phosphatase, osteocalcin, type-I-collagen, osteoprotegerin, and glyceraldehyde-3-phosphate-dehydrogenase) detected by RT-PCR was highest on the modSLA surface. In conclusion it has been demonstrated that the modSLA surface results in an enhanced cluster formation of osteoblasts grown on this surface and in an increased expression of key osteogenic regulatory genes in osteoblasts.

Effects of surface hydrophilicity and microtopography on early stages of soft and hard tissue integration at non-submerged titanium implants: an immunohistochemical study in dogs.

BACKGROUND: The aim of the present study was to investigate the effects of surface hydrophilicity and microtopography on soft and hard tissue integration at non-submerged titanium implants. METHODS: Implantation of conventional sand-blasted large grit and acid-etched (SLA) and chemically modified SLA (modSLA) titanium implants with differently structured transmucosal surfaces (SLA implants: machined [M-SLA] or SLA [SLA-SLA]; modSLA implants: mod acid-etched [modA] [modA-modSLA] or modSLA [modSLA-modSLA]) was performed bilaterally in the upper and lower jaws of 15 beagle dogs. The animals were sacrificed after 1, 4, 7, 14, or 28 days. Tissue reactions were assessed histomorphometrically and immunohistochemically using monoclonal antibodies to transglutaminase II (angiogenesis) and osteocalcin. RESULTS: Although the junctional epithelium commonly was separated from M-SLA and SLA-SLA implants by a gap, the epithelial cells appeared to be in close contact with modA-modSLA surfaces after 14 days of healing. Moreover, modA-modSLA and modSLA-modSLA groups showed a well-vascularized subepithelial connective tissue exhibiting collagen fibers that started to extend and attach partially perpendicular to the implant surface. The highest and statistically significant mean bone-to-implant contact areas were observed in the modA-modSLA and modSLA-modSLA groups at days 7, 14, and 28. CONCLUSION: Within the limits of this study, it may be concluded that soft and hard tissue integration was influenced mainly by surface hydrophilicity rather than by microtopography.

Integrin beta1 silencing in osteoblasts alters substrate-dependent responses to 1,25-dihydroxy vitamin D3.

Surface microroughness increases osteoblast differentiation and enhances responses of osteoblasts to 1,25-dihydroxyvitamin D3 [1alpha,25(OH)2D3]. The observations that beta1 integrin expression is increased in osteoblasts grown on Ti substrates with rough microarchitecture, and that it is regulated by 1alpha,25(OH)2D3 in a surface-dependent manner, suggest that beta1 may play a role in mediating osteoblast response. To test this hypothesis, we silenced beta1 expression in MG63 human osteoblast-like cells using small interfering RNA (siRNA) and examined the responses of the beta1-silenced osteoblasts to surface microtopography and 1alpha,25(OH)2D3. To better understand the role of beta1, MG63 cells were also treated with two different monoclonal antibodies to human beta1 to block ligand binding. beta1-silenced MG63 cells grown on a tissue culture plastic had reduced alkaline phosphatase activity and levels of osteocalcin, transforming growth factor beta1, prostaglandin E2, and osteoprotegerin in comparison with control cells. Moreover, beta1-silencing inhibited the effects of surface roughness on these parameters and partially inhibited effects of 1alpha,25(OH)2D3. Anti beta1 antibody AIIB2 had no significant effect on cell number and osteocalcin, but decreased alkaline phosphatase; MAB2253Z caused dose-dependent decreases in cell number and alkaline phosphatase and an increase in osteocalcin. Effects of 1alpha,25(OH)2D3 on cell number and alkaline phosphatase were reduced and effects on osteocalcin were increased. These findings indicate that beta1 plays a major and complex role in osteoblastic differentiation modulated by either surface microarchitecture or 1alpha,25(OH)2D3. The results also show that beta1 mediates, in part, the synergistic effects of surface roughness and 1alpha,25(OH)2D3.

Synergistic interaction of topographic features in the production of bone-like nodules on Ti surfaces by rat osteoblasts.

The objective of this study was to study the responses of osteoblast-like cells to rough Titanium (Ti)-coated epoxy surfaces of differing topographic complexity. Four topographies were studied: polished (PO), coarse-blasted (CB), acid-etched (AE) and coarse-blasted+acid-etched (SLA). Rat osteoblasts were cultured on these surfaces and their morphology, thickness as well as the number and size of bone-like nodules measured. To determine cell shape and cell thickness, fluorescein-5-thiosemicarbazide was used to stain the cell components including the cell membrane, the stained cells were optically sectioned using epifluorescent microscopy and the optical sections were computationally reconstructed to obtain three-dimensional images in which cell volume and cell thickness could be determined. Similarly optical sections of bone-like nodules labeled with tetracycline were also reconstructed to determine their size. The different surface topographies were found to alter the thickness and morphology of osteoblasts cultured on these surfaces. Osteoblasts produced significantly more and larger nodules on SLA compared to other surfaces. Nevertheless and perhaps surprisingly, given the evidence in various cell populations that cell shape can affect cell differentiation, cell thickness was not directly correlated with an increase in bone-like nodule formation. Data were analyzed by factorial analysis of variance. In this way the primary effect of each surface treatment ( i.e. blasting and acid etching) could be assessed as well as their interaction. Both the acid etching and blasting processes significantly affected the number and size of bone-like nodules cultured on Ti surfaces. Moreover there were significant interaction effects indicating that surface topographic features can act synergistically to enhance bone formation. This result suggests that a useful approach to the optimization of surfaces for bone production could involve systematic investigation of combinations of processes each of which produces distinct surface topographical features.

Surface reactions of 4-aminothiophenol with heterobifunctional crosslinkers bearing both succinimidyl ester and maleimide for biomolecular immobilization.

Surface reactions of 4-aminothiophenol (4-ATP) with a series of heterogeneous crosslinkers containing both maleimide and succinimidyl ester groups were investigated with infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS). Two types of surface reactions exist: (1) for most crosslinkers, a dominant reaction of amine and succinimidyl ester gave homogeneous maleimide-pendant surfaces; (2) for other crosslinkers, a side reaction between amine and maleimide, accompanying the main reaction, yielded heterogeneous surfaces with two linking groups, maleimide and succinimidyl ester. A typical example for the second case is the reaction of surface amines with N-succinimidyl-6-maleimidylhexanoate (SMH). Finally, a peptide, H-Gly-Arg-Gly-Asp-Ser-Pro-Cys-OH (GRGDSPC), was immobilized on the SMH-derived surface as a bridging structure through two linkages, cysteine thioether and glycine amide.

Polyspecies biofilm formation on implant surfaces with different surface characteristics.

OBJECTIVE: To investigate the microbial adherence and colonization of a polyspecies biofilm on 7 differently processed titanium surfaces. MATERIAL AND METHODS: Six-species biofilms were formed anaerobically on 5-mm-diameter sterilized, saliva-preconditioned titanium discs. Material surfaces used were either machined, stained, acid-etched or sandblasted/acid-etched (SLA). Samples of the latter two materials were also provided in a chemically modified form, with increased wettability characteristics. Surface roughness and contact angles of all materials were determined. The discs were then incubated anaerobically for up to 16.5 h. Initial microbial adherence was evaluated after 20 min incubation and further colonization after 2, 4, 8, and 16.5 h using non-selective and selective culture techniques. Results at different time points were compared using ANOVA and Scheffé post hoc analysis. RESULTS: The mean differences in microorganisms colonizing after the first 20 min were in a very narrow range (4.5 to 4.8 log CFU). At up to 16.5 h, the modified SLA surface exhibited the highest values for colonization (6.9±0.2 log CFU, p<0.05) but increasing growth was observed on all test surfaces over time. Discrepancies among bacterial strains on the differently crafted titanium surfaces were very similar to those described for total log CFU. F. nucleatum was below the detection limit on all surfaces after 4 h. CONCLUSION: Within the limitations of this in vitro study, surface roughness had a moderate influence on biofilm formation, while wettability did not seem to influence biofilm formation under the experimental conditions described. The modified SLA surface showed the highest trend for bacterial colonization.

Submicron scale-structured hydrophilic titanium surfaces promote early osteogenic gene response for cell adhesion and cell differentiation.

BACKGROUND AND PURPOSE: Titanium (Ti) surface roughness and surface hydrophilicity are key factors to regulate osteogenic cell responses during dental implant healing. In detail, specific integrin-mediated interactions with the extracellular environment trigger relevant osteogenic cell responses like differentiation and matrix synthesis via transcriptions factors. Aim of this study was to monitor surface-dependent osteogenic cell adhesion dynamics, proliferation, and specific osteogenic cell differentiation over a period of 7 days. MATERIALS AND METHODS: Ti disks were manufactured to present smooth pretreatment (PT) surfaces and rough sandblasted/acid-etched (SLA) surfaces. Further processing to isolate the uncontaminated TiO(2) surface from contact with atmosphere provided a highly hydrophilic surface without alteration of the surface topography (modSLA). Tissue culture polystyrene (TCPS) served as control. Human osteogenic cells were cultivated on the respective substrates. After 24 hours, 48 hours, 72 hours, and 7 days, cell morphology on the Ti substrates was visualized by scanning transmission electron microscopy. As a marker of cellular proliferation, cell count was assessed. For the analysis of cell adhesion and differentiation, specific gene expression levels of the integrin subunits ß1 and αv, runx-2, collagen type Iα (COL), alkaline phosphatase (AP), and osteocalcin (OC) were obtained by real-time RT-PCR for the respective time points. Data were normalized to internal controls. RESULTS: TCPS and PT surfaces preserved a rather immature, dividing osteogenic phenotype (high proliferation rates, low integrin levels, and low specific osteogenic cell differentiation). SLA and especially modSLA surfaces promoted both cell adhesion as well as the maturation of osteogenic precursors into post-mitotic osteoblasts. In detail, during the first 48 hours, modSLA resulted in lowest cell proliferation rates but exhibited highest levels of the investigated integrins, runx-2, COL, AP, and OC. CONCLUSION: Our results revealed a strong synergistic effect between submicron-scale roughness and surface hydrophilicity on early osteogenic cell adhesion and maturation.

Initial attachment, subsequent cell proliferation/viability and gene expression of epithelial cells related to attachment and wound healing in response to different titanium surfaces.

OBJECTIVES: A tight seal between the epithelium and the dental implant surface is required to prevent bacterial inflammation and soft tissue recession and therefore to demonstrate a long-term success. Surface hydrophilicity was recently shown to promote osseointegration. The aim of this study was to investigate the influence of surface hydrophilicity in combination with surface topography of Ti implant surfaces on the behavior and activation/differentiation of epithelial cells using a set of in vitro experiments mimicking the implant-soft tissue contact. METHODS: Hydrophobic acid-etched (A) and coarse-grit-blasted, acid-etched (SLA) surfaces and hydrophilic acid-etched (modA) and modSLA surfaces were produced. The behavior of an oral squamous cell carcinoma cell line (HSC-2) grown on all surfaces was compared through determination of cell attachment and proliferation/viability (CCK-8 and MTT assay), time-lapse microscopy of fluorescence labeled cells and determination of gene expression by real time polymerase chain reaction. RESULTS: Within the surfaces with similar wettability cell spreading and cell movements observed by time-lapse microscopy after one day of incubation were most pronounced on smoother (A and modA) surfaces compared to rougher (SLA and modSLA) surfaces. Within the surfaces with similar roughness the hydrophilic surfaces (modA and modSLA) showed more cell spreading and cell activity compared to the hydrophobic surfaces (A and SLA). The relative gene expressions of cytokeratin14, integrin α6, integrin ß4, vinculin, transforming growth factor (TGF)-ß, TGF-ß1, and TGF-ß3 were decreased in HSC-2 on all four types of Ti surfaces compared to control surfaces (tissue culture polystyrene; p<0.01) and there was no significant difference of gene expression on the four different implant-surfaces. SIGNIFICANCE: We have demonstrated that for proliferation and spreading of HSC-2 cells the smoother and hydrophilic surface is optimal (modA). These results suggest that surface hydrophilicity might positively influence the epithelial seal around dental implants. All tested titanium surfaces downregulate cell attachment, cell proliferation, expression of adhesion promoters, and cytokines involved in wound healing in HSC-2 cells compared to control surfaces.

Primary stability of a hybrid self-tapping implant compared to a cylindrical non-self-tapping implant with respect to drilling protocols in an ex vivo model.

BACKGROUND: Modifications of implant design have been intending to improve primary stability. However, little is known about investigation of a hybrid self-tapping implant on primary stability. PURPOSES: The aims of this study were to evaluate the primary stability of two hybrid self-tapping implants compared to one cylindrical non-self-tapping implant, and to elucidate the relevance of drilling protocols on primary stability in an ex vivo model. MATERIALS AND METHODS: Two types of hybrid self-tapping implants (Straumann® Bone Level implant [BL], Straumann® Tapered Effect implant [TE]) and one type of cylindrical non-self-tapping implant (Straumann® Standard Plus implant [SP]) were investigated in the study. In porcine iliac cancellous bones, 10 implants each were inserted either using standard drilling or under-dimensioned drilling protocol. The evaluation of implant-bone interface stability was carried out by records of maximum insertion torque, the Periotest® (Siemens, Bensheim, Germany), the resonance frequency analysis (RFA), and the push-out test. RESULTS: In each drilling group, the maximum insertion torque values of BL and TE were significantly higher than SP (p=.014 and p=.047, respectively). In each group, the Periotest values of TE were significantly lower than SP (p=.036 and p=.033, respectively). The Periotest values of BL and TE were significantly lower in the group of under-dimensioned drilling than standard drilling (p=.002 and p=.02, respectively). In the RFA, no statistical significances were found in implants between two groups and between implants in each group. In each group, the push-out values of BL and TE were significantly higher than SP (p=.006 and p=.049, respectively). CONCLUSION: Hybrid self-tapping implants could achieve a high primary stability which predicts them for use in low-density bone. However, there is still a debate to clarify the influence of under-dimensioned drilling on primary stability.

The roles of Wnt signaling modulators Dickkopf-1 (Dkk1) and Dickkopf-2 (Dkk2) and cell maturation state in osteogenesis on microstructured titanium surfaces.

Osteoblast differentiation on tissue culture polystyrene (TCPS) requires Wnt/beta-catenin signaling, regulating modulators of the Wnt pathway like Dickkopf-1 (Dkk1) and Dkk2. Osteoblast differentiation is increased on microstructured titanium (Ti) surfaces compared to TCPS; therefore, we hypothesized that surface topography and hydrophilicity affect Dkk1 and Dkk2 expression and that their roles in osteoblast differentiation on Ti differs depending on cell maturation state. Human osteoblast-like MG63 cells, normal human osteoblasts (HOBs), and human mesenchymal stem cells (MSCs), as well as MG63 cells stably silenced for Dkk1 or Dkk2 were grown for 6 days on TCPS and Ti surfaces (PT [Ra<0.2 microm], SLA [Ra=4 microm], modSLA [hydrophilic-SLA]). Dkk1 and Dkk2 mRNA and protein increased on SLA and modSLA for all cell types, but exogenous rhDkk1 and rhDkk2 affected MSCs differently than MG63 cells and HOBs. Silencing Dkk1 reduced MG63 cell number on TCPS and PT, but increased differentiation on these substrates. Silencing Dkk2 reduced stimulatory effects of SLA and modSLA on osteoblast differentiation; Dkk2 but not Dkk1 restored these effects. Antibodies to Dkk1 or Dkk2 specifically blocked substrate-dependent changes caused by the proteins, demonstrating their autocrine action. This indicates major roles for Dkk1 and the canonical Wnt pathway in early-stage differentiation, and for Dkk2 and Wnt/Ca2+-dependent signaling in late-stage differentiation on microstructured and hydrophilic surfaces, during osseointegration.

A comparison study of the osseointegration of zirconia and titanium dental implants. A biomechanical evaluation in the maxilla of pigs.

OBJECTIVES: The purpose of the present study was to investigate the osseointegration of microstructured zirconia implants in comparison with sandblasted and acid-etched (SLA) titanium implants in a biomechanical study. MATERIALS: Zirconia implants (4.1 mm in diameter, 10 mm in length) were produced using a new low pressure injection molding technique. After that the implants were acid-etched with hydrofluoric acid. Standard Ti-SLA implants of the exact same shape served as controls. Six months after extraction of incisors 2 and 3, 16 adult pigs received a total of 64 implants in the maxillae. After 4, 8, and 12 weeks the animals were sacrificed, and 59 implants could be analyzed to removal torque (RTQ) testing. RESULTS: The mean RTQ values for zirconia implants were 42.4 Ncm at 4 weeks, 69.6 Ncm at 8 weeks, and 69.3 Ncm at 12 weeks of healing, whereas RTQ values for the Ti-SLA implants were 42.1 Ncm, 75.0 Ncm, and 73.1 Ncm at corresponding time intervals. There is no statistical difference in RTQ values between Ti-SLA and zirconia implants at 8 weeks. CONCLUSIONS: Within the limits of the present study it was concluded that acid-etching of zirconia implants enhances bone apposition resulting in RTQ values which were equivalent to that of Ti-SLA.