Changes in proinflammatory gene expression in human whole blood after contact with UV-conditioned implant surfaces.

OBJECTIVES: The aim of this in vitro study was to assess changes in the gene expression of proinflammatory cytokines in human whole blood after contact with titanium implant surfaces conditioned by UV light. To this end, expression levels of proinflammatory cytokines were analyzed in vitro in human whole blood. MATERIALS AND METHODS: Dental implants made of grade 4 titanium were conditioned by UV light in a UV device and submerged in human whole blood. Unconditioned implants served as controls, and blood samples without implants served as the negative control group. Sampling was performed at 1, 8, and 24 h. Changes in the expression levels of interleukin-1ß (IL1B) and tumor necrosis factor alpha (TNF) were assessed using RT-qPCR at the mRNA level. RESULTS: The gene expression of IL1B was significantly suppressed in the test group over the observation period compared to the control group during the 1-8 h after having contact between the implant surface and the blood. The gene expression of TNF was not significantly altered by UV conditioning after 1 and 8 h of observation, but both cytokine expression levels were increased significantly after 24 h. CONCLUSIONS: Differences in the gene expression of proinflammatory cytokines after insertion of UV-conditioned titanium implants can be assessed using a human whole blood test. UV-conditioned implant surfaces apparently suppress the release of IL1B in vitro. CLINICAL RELEVANCE: The results of our publication demonstrate that modulation of the early inflammatory response in human whole blood is possible by surface treatment with UV light. In particular, the suppression of IL1B expression, especially after the initial contact of blood cells, may be beneficial in the osseointegration of titanium implants by positively influence the balance between rejection and acceptance of an implant.

Retention of zirconia on titanium in two-piece abutments with self-adhesive resin cements.

STATEMENT OF PROBLEM: Two-piece abutments consisting of a prefabricated titanium luting base and a zirconia abutment are used widely in implant restorations. Straightforward and reliable procedures for bonding titanium and zirconia are necessary for ensuring low failure rates in such restorations. PURPOSE: The purpose of this in vitro study was to evaluate the tensile load of zirconia copings on prefabricated titanium abutments using 4 different self-adhesive resin cements. MATERIAL AND METHODS: A total of 128 industrially manufactured partially yttria-stabilized zirconia ceramic copings were bonded to titanium abutments with a luting space of about 60 µm or 100 µm. The bonding surfaces were airborne-particle abraded with 50 µm alumina and cleaned ultrasonically. The zirconia copings were bonded with Panavia SA Cement Automix (SA), RelyX Unicem 2 Automix (RU), MaxCem Elite (ME), or SmartCem 2 (SC). Specimens from each cement group were randomly assigned to be stored either in distilled water (37°C) for 3 days or subjected to 37 500 thermocycles over 150 days. After debonding in tension, failure modes (adhesive or cohesive) were analyzed, and basic fuchsin dye penetration tests were performed using optical microscopy and scanning electron microscopy. Three-way ANOVA and Tukey HSD tests were used for statistical analysis (α=.05). RESULTS: Three-way ANOVA results determined that the luting resin used and the luting space had a significant effect (P≤.002), while the storage time did not have an overall effect (P>.05). The interaction between the luting resin used and storage time was significant (P<.001). After storage for 3 days, the retentive force of SA (1002 N) was highest, followed by that for RU (614 N), ME (550 N), and SC (346 N) (P≤.05); the forces for RU and ME were not significantly different (P>.05). However, after thermocycling, RU had the highest retentive force (848 N), followed by SA (646 N), ME (475 N), and SC (364 N) (P≤.05). Retentive forces for ME and SC were not significantly different (P>.05). The failure modes of the zirconia abutment surfaces were predominantly adhesive, while those of the titanium surfaces were mainly cohesive. The SA specimens showed the lowest dye penetration, followed by the RU, ME, and SC specimens. CONCLUSIONS: The greatest mean retention was found with Panavia SA Cement Automix and RelyX Unicem 2 Automix with a luting space of 60 µm when bonding zirconia copings to titanium.

Retention of bonded titanium copings fixed to implant abutments.

STATEMENT OF PROBLEM: Conical abutments can be laser welded to the abutment base to compensate for differing implant axes. As laser welding requires expensive equipment, alternative methods for bonding the conical abutment part with the abutment base should be considered. PURPOSE: The purpose of this in vitro study was to evaluate the retention of Ti-6Al-7Nb copings bonded adhesively to Ti-6Al-7Nb abutments and to compare it with the stability achieved by laser welding. MATERIAL AND METHODS: A total of 104 two-part Ti-6Al-7Nb specimens were prepared and divided into 13 groups with 8 specimens each. In this 2-part study, 3 luting resins (Panavia F 2.0 [PF]; Multilink Automix [MA]; Superbond C&B [SB]) were used with or without metal priming (PR). The laser welding group (LW) served as the control. After storage for 1 or 150 days (150 days with thermal cycling [TC]), push-out retention and welded joint stability were tested. The data were analyzed with ANOVA and the Tukey HSD multiple comparison tests. RESULTS: The choice of resin, thermal cycling, and metal priming had a significant effect on resin push-out retention. LW provided the strongest retention, followed by PF, MA, and SB. For PF and SB, TC decreased retention. PR did not lead to higher retention but provided better bonding stability when TC was applied. CONCLUSIONS: The retention values suggest that considering the maximum mastication forces, resin bonding is an appropriate substitute for the laser welding method.

Impact of vertical loading on the implant-bone interface.

OBJECTIVES: The main aim of this study was to evaluate the impact of vertical loading occurring during removal of cemented restorations on the implant-bone interface. METHODS: Thirty-six titanium implants (Camlog 4.3 × 9 mm) were placed 1 mm supraosseous in the frontal skull of four minipigs. After a 13 week healing period the implants were exposed and the implant stability was measured. Three implants per minipig were vertically loaded using 20 or 100 impulses, respectively with an 18 Ns impulse imitating a crown removal. Three implants were left unloaded as control. The animals were sacrificed after 13 or 18 weeks. The harvested specimens were analyzed using scanning electron microscopy (SEM), light and fluorescence microscopy. RESULTS: No post operative complications or deaths of the minipigs occurred. All implants osseointegrated. The average bone-implant contact area (BIC) was 78 ± 5.1%. No statistically significant difference could be found when comparing the BIC areas of the control and the experimental groups between the sacrificed animals at 13 weeks and 18 weeks (P > 0.05). Therefore, the results of each subgroup were pooled. No significant differences regarding the BIC area could be detected between the control and the experimental groups (P > 0.05). Except one failing implant no cracks due to vertical loading could be evaluated in the SEM. Fluorescence microscopy revealed a significantly higher bone remodeling activity in the vertically loaded groups. CONCLUSIONS: Removal of cemented implant restorations seems not to have an impact on the mechanical implant stability, but seems to increase bone remodeling activity.

Influence of peripheral enamel bonding and chlorhexidine pretreatment on resin bonding to dentin.

PURPOSE: To evaluate the influence of peripheral enamel bonding, chlorhexidine digluconate (CHX) pretreatment, and storage time on resin-dentin microtensile bond strength (µTBS) of a self-etching adhesive system and selfetching cement. MATERIALS AND METHODS: Fifty-six noncarious human third molars were coronally sectioned to provide a flat dentin surface; the circumferential enamel was removed from half of these and the other half was left intact. Pretreatment with 0.2% or 2% CHX or none (control) was performed before bonding composite blocks with Panavia F2.0 or RelyX Unicem to dentin. Specimens were stored in 0.5% chloramine for 3 days (control) or 6 months. Bonded specimens were sectioned into 1-mm2 dentin-only beams and a tensile load was applied until failure. The resulting 14 test groups, defined by control group/storage time/cement/CHX application mode/enamel bonding, were analyzed using two-way and three-way ANOVA, as well as Tukey's HSD post-hoc test (α = 0.05). Failure patterns of the specimens were observed and measured using scanning electron microscopy. RESULTS: The comparison of the control vs experimental subgroups with peripheral enamel bonding and without CHX pretreatment after six months found no significant differences regarding the µTBS between the cements (p > 0.05) but did for the storage time (p <= 0.05). When storing the specimens for six months, the absence of peripheral enamel bonding significantly decreased the µTBS (p <= 0.05). Panavia F2.0 specimens showed significantly higher µTBS values than RelyX Unicem specimens (p <= 0.05). CHX pretreatment, regardless the concentration, showed a significant influence on the µTBS (p <= 0.05). SEM revealed that peripheral enamel bonding reduced failures at the resin/dentin interface. CONCLUSIONS: The absence of peripheral enamel bonding and a longer storage time decrease the µTBS of twostep self-etching adhesive system and a one-step self-etching cement. CHX pretreatment of the dentinal surfaces seems to improve the durability of the bond to dentin.

Analysis of the intraimplant microflora of two-piece dental implants.

OBJECTIVE: Information about the spectrum of microorganisms in the intraimplant cavities of two-piece dental implants is scarce. The purpose of this study was to assess the intraimplant microflora of two-piece dental implants by conventional biochemical testing, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and 16 s rDNA gene sequencing. MATERIALS AND METHODS: Ten patients (six men and four women; average age = 66.7 years; age range = 58-78 years) received 35 two-piece titanium implants carrying ball attachments. Biofilm sampling was performed with sterile microbrushes, and nonadherent microbial samples were obtained by injection and reuptake of predefined volumes of NaCl solution. The samples were cultured and analyzed by conventional biochemical testing, MALDI-TOF MS, and 16 s rDNA gene sequencing. RESULTS: Of the 103 species detected, 27 and 33 were identified only in the biofilm and nonadherent microbial samples, respectively. Forty-three species were identified in both types of samples. CONCLUSIONS: Two-piece dental implants harbored a broad spectrum of gram-positive and gram-negative aerobes and anaerobes, especially rods and cocci. CLINICAL RELEVANCE: These findings confirm bacterial translocation from the oral cavity to intraimplant cavities. Microbiological methods as used in this study are necessary to reveal the complete vital microflora of intraimplant cavities.

Influence of cement film thickness on the retention of implant-retained crowns.

PURPOSE: The main goal of this study was to establish a new, high precision procedure to evaluate the influence of cement film thickness on the retention of cemented implant-retained crowns. MATERIALS AND METHODS: Ninety-six tapered titanium abutments (6° taper, 4.3 mm diameter, Camlog) were shortened to 4 mm. Computer-aided design was used to design the crowns, and selective laser sintering, using a cobalt-chromium alloy, was used to produce the crowns. This method used a focused high-energy laser beam to fuse a localized region of metal powder to build up the crowns gradually. Before cementing, preset cement film thicknesses of 15, 50, 80, or 110 µm were established. Glass ionomer, polycarboxylate, or resin cements were used for cementation. After 3 days storage in demineralized water, the retention of the crowns was measured in tension using a universal testing machine. RESULTS: The cement film thicknesses could be achieved with a high level of precision. Interactions between the factors cement and cement film thickness could be found (p ≤ 0.001). For all cements, crown retention decreased significantly between a cement film thickness of 15 and 50 µm (p ≤ 0.001). At 15 µm cement film thickness, the resin cement was the most retentive cement, followed by the polycarboxylate and then the glass ionomer cement (p ≤ 0.05). CONCLUSIONS: The results suggest that cement film thickness has an influence on the retentive strength of cemented implant-retained crowns.

Surface contamination of dental implants assessed by gene expression analysis in a whole-blood in vitro assay: a preliminary study.

AIM: We aimed at evaluating pyrogen contamination of dental implants made of titanium and zirconia by using gene expression analysis in a whole-blood in vitro assay. MATERIAL AND METHODS: Titanium and zirconia implants (five each) were incubated in human whole blood. Samples were assayed for gene expression levels of toll-like receptor 4 (TLR4), TLR9, interleukin (IL)-1ß, nuclear factor 'kappa-light-chain-enhancer' of activated B-cells (NF-kB), tumour necrosis factor (TNF)-α, and Fas-associated protein with death domain (FADD) as indicators of surface contamination resulting in lipopolysaccharides (LPS)-stimulated TLR- or TNF-mediated immune responses. Gene expression was assayed using real-time quantitative polymerase chain reaction (RT-qPCR). Non-stimulated blood from the same donor served as a negative control, and blood stimulated with LPS served as a positive control. After dry-heat treatment with dry heat, all implants were re-analysed as described above. RESULTS: Both implant systems contained surface contaminants evoking a pro-inflammatory response similar to that induced by LPS. After dry-heat treatment, gene expression was significantly decreased to levels similar to those of negative control samples. CONCLUSIONS: The results demonstrated LPS-like surface-bound contaminants in both tested implant systems. Depyrogenation with dry heat seems to be an effective means of reducing such contamination in dental implants.

In vitro influence of ultrasonic stress, removal force preload and thermocycling on the retrievability of implant-retained crowns.

OBJECTIVES: The main goals of this in vitro study were to evaluate the influence of thermocycling, ultrasonic stress and the removal force preload on the retrievability of cemented implant crowns using a clinical removal device (Coronaflex) and evaluating the tensile strength using a universal testing machine (UTM). METHODS: Thirty-six crowns were cast from a Co-Cr alloy for 36 tapered titanium abutments (5° taper, 4.3 mm diameter, 6 mm height, Camlog, Germany). The crowns were cemented with a glass-ionomer (Ketac Cem) or a polycarboxylate (Durelon) cement, followed by 3 days of storage in ionized water without thermocycling or 150 days of storage with 37,500 thermal cycles between 5°C and 55°C. Before removal, the crowns were subjected to ultrasonic stress for 0, 5 or 10 min with a contact pressure of either 50 or 500 g. The Coronaflex was used with a removal force preload of 50 or 400 cN, respectively, applied on the point of loading. Scanning electronic microscopy (SEM) was used to evaluate the impact of the removal on the abutment screws. RESULTS: Crowns cemented with the glass-ionomer cement were significantly easier to remove with the Coronaflex or the UTM than crowns cemented with the polycarboxylate cement (P≤0.05). Ultrasonic stress showed no significant impact on the retrievability regardless of the contact pressure or duration applied (P>0.05). No significant differences could be found for both cements when removed with the Coronaflex or the UTM (P>0.05) after thermocycling was applied. A removal force preload of 400 cN resulted in significantly reduced removal attempts in comparison with 50 cN for both cements (P≤0.05). CONCLUSIONS: Ultrasound and thermal cycling did not result in reduced cement strength, but to retrieve the crowns, the full impact of a removal instrument has to be applied. Ketac Cem can be used as a "semipermanent" solution, whereas Durelon might serve for permanent cementation. None of the abutment screws showed signs of wear caused by the removal process.

Microstructure analysis of dental castings used in fixed dental prostheses--a simple method for quality control.

The aim of this study was to evaluate the microstructural quality of noble alloy castings from commercial dental laboratories using the wiping-etching method as a simple method for quality control. In total, 240 castings from two noble alloys (AuAgCuPt and AuPtZn) were taken from a day's production of five different dental laboratories. The casting quality was evaluated by determining the grain size and by assessing the number and size of shrinkage cavities after acidic etching of the alloy surfaces. The AuAgCuPt alloy castings showed an acceptable quality in the microstructural analysis. The results of AuPtZn castings, however, were not satisfactory because 50.8% of the samples showed a remarkably poorer quality compared to the specifications made by the manufacturer. The proportion of the employed reclaimed alloy had no influence on the casting quality when AuAgCuPt alloy was used, but was influential when casting restorations with AuPtZn alloy. When determining the quantity and size of shrinkage cavities, none of the evaluated castings was of such a poor quality that a replacement of the castings had to be considered. The differences in grain size and quantity of shrinkage cavities were reflecting the individual laboratory process rather than the admixture of new/reclaimed alloy. The presented analysis can be used as a simple method for quality control of dental castings.

Patients' and dentists' perception of dental appearance.

The purpose of this study was to compare the patients' and dentists' perception of dental appearance. Based on internationally accepted guidelines about dental esthetics, a questionnaire was developed to measure "dental appearance" (QDA). Eleven items defined a QDA sum score (0 = "absolutely satisfied", 44 = "absolutely dissatisfied"). The QDA was completed by 16 patients (eight women, eight men, mean age 63 ± 9 years) before and after a complete oral rehabilitation. Forty-two dentists evaluated the esthetics before and after rehabilitation on a visual analog scale (VAS, 0 = "absolutely unesthetic", 100 = "absolutely esthetic"). The patients' quoting showed a significant esthetic improvement (QDA sum score) from 22 before treatment to 3.5 after treatment (P ≤ 0.001). Although most of the dentists judged an improvement in most of the patients dental appearances, no significant correlation could be found between patients' and dentists' judgment regarding dental appearance (r = -0.13-0.53, P > 0.05). When evaluating the influence of age, gender, and experience on rating dental appearance, no significant differences (P > 0.05) could be found.

Single-cell adhesion of human osteoblasts on plasma-conditioned titanium implant surfaces in vitro.

OBJECTIVES: This study aimed to demonstrate the effect of treating titanium-implant surfaces with plasma from two different sources on wettability and initial single-cell adhesion of human osteoblasts and to investigate whether aging affects treatment outcomes. METHODS: Titanium disks with sandblasted and acid-etched (SLA) surfaces were treated with atmospheric pressure plasma (APP) and low-pressure plasma (LPP). For wetting behavior of the specimens after plasma treatment, the water contact angle was measured. The single-cell detachment force and amount of work of detachment of human osteoblasts were determined with single-cell force spectroscopy (SCFS). To evaluate the aging effect in APP-treated specimens, SCFS was conducted 10 and 60 min after treatment. RESULTS: Significantly higher hydrophilicity was observed in the APP and LPP treatment groups than in the control group, but no significant difference was observed between the APP and LPP groups. No significant difference in cell-detachment force or work of detachment was observed, and there were no significant differences according to the conditioning mechanisms and storage time. SIGNIFICANCE: Conditioning of the titanium surfaces with APP or LPP was not a significant influencing factor in the initial adhesion of the osteoblasts.

Performance of ultrasonic devices for bone surgery and associated intraosseous temperature development.

PURPOSE: The purpose of this study was to evaluate and to compare the bone-cutting performance and intraosseous temperature development of three modern ultrasonic devices for bone surgery (UDBS). MATERIALS AND METHODS: The following UDBS and associated cutting tips (straight bone saws) were used in this study: (1) Piezosurgery II professional, tip OT 7 (Mectron); (2) Piezotome, tip BS 1 (Acteon); and (3) SurgySonic, tip ES007 (American Dental Systems/Gunther Jerney). In the experimental setup UDBS, handpieces were immobilized, and bone specimens from the middiaphysis of a bovine femur were moved in a longitudinal direction under the cutting tip to a standardized depth of 3.0 mm. Intraosseous temperature development was measured using a glass-fiber isolated thermocouple. The cutting performance was defined by the time required to reach the cutting depth of 3.0 mm. Statistical analysis was performed using the Wilcoxon rank sum test. RESULTS: The median increase (25th through 75th percentiles) of the local intraosseous temperature was 3.0 degrees C (2.2 degrees C to 4.2 degrees C) for the SurgySonic, 2.2 degrees C (1.8 degrees C to 3.2 degrees C) for the Piezosurgery II, and 1.1 degrees C (0.7 degrees C to 1.6 degrees C) for the Piezotome. The median cutting performance was 0.31 mm/s (0.11 to 0.46 mm/s) for the Piezotome, 0.25 mm/s (0.23 to 0.27 mm/s) for the Piezosurgery II, and 0.04 mm/s (0.03 to 0.05 mm/s) for the SurgySonic. CONCLUSIONS: Among the three tested UDBS, the Piezotome and the Piezosurgery II showed a significantly higher cutting performance than the SurgySonic. The Piezotome produced the smallest increase in intraosseous temperature.

Retrievability of implant-retained crowns following cementation.

OBJECTIVES: The purpose of this study was to assess the retrievability of cemented implant crowns using two different removal devices. The influence of five cement types and two cement application techniques was evaluated. METHODS: Forty copings were cast from a CoCr alloy for 40 tapered titanium abutments (5 degrees taper, 4.3 mm diameter, 6 mm height, Camlog, Germany). Twenty copings were modeled as single crowns, whereas 20 copings were modeled with an extension to simulate fixed partial dentures (FPDs). Before cementation, the inner surfaces of the copings were air-abraded (50 mum Al(2)O(3) particles at 2.5 bars), while the abutments were used as delivered with machined surfaces. Copings were cemented with eugenol-free zinc oxide (Freegenol), zinc phosphate (Harvard), glass ionomer (Ketac Cem), polycarboxylate (Durelon) and so-called self-adhesive resin (RelyX Unicem) cement. Cement was applied in a thin film band of 1 or 3 mm to the cervical margin of the inner surface of the copings, respectively. After cementation, specimens were stored in saline solution for 24 h. The Coronaflex and a standardized custom-made removal device were used to remove the copings from the abutments. RESULTS: Using the same cement, no statistically significant influence with regard to the type of restoration (crown/FDP), cement application mode and device was detected (P>0.05). Therefore, data of specimens cemented with the same cement were pooled. Median attempts to remove the copings were: zinc oxide: 3, self-adhesive resin: 3, zinc phosphate: 5, glass ionomer: 16 and polycarboxylate: 58. Four levels of significance (P<0.0001) were found: (1) zinc oxide/self-adhesive resin; (2) zinc phosphate; (3) glass ionomer; and (4) polycarboxylate. CONCLUSIONS: Zinc phosphate and glass ionomer cement might be suitable for a so-called 'semipermanent' (=retrievable) cementation, while polycarboxylate seems to provide the most durable cementation.

Effect of ultraviolet photofunctionalization of dental titanium implants on osseointegration.

OBJECTIVE: The aim of the current study was to evaluate the effect of ultraviolet (UV) photofunctionalization of dental titanium implants with exposure to the oral cavity on osseointegration in an animal model. METHODS: Forty-eight titanium implants (Camlog® Conelog® 4.3 mmx9.0 mm) were placed epicrestally into the edentulous jaws of three minipigs and implant stability was assessed by measuring the implant stability quotient (ISQ). Prior to implantation half of the implants were photofunctionalized with intense UV-light. After three months, the implants were exposed and ISQ was measured again. After six months of implant exposure, the minipigs were sacrificed and the harvested specimens were analyzed using histomorphometric, light, and fluorescence microscopy. MAIN RESULTS: Forty-two of 48 implants osseointegrated. The overall mean bone-implant contact area (BIC) was (64±22)%. No significant differences were found in BIC or ISQ value (multivariate analysis of variance (MANOVA), P>0.05) between implants with and without exposure to UV photofunctionalization. CONCLUSIONS: No significant effects were observed on osseointegration of dental titanium implants nine months after exposure of UV photofunctionalization.

Intraosseous Temperature Changes During Implant Site Preparation: In Vitro Comparison of Thermocouples and Infrared Thermography.

PURPOSE: Implant-supported dental prostheses are based on the principle of osseointegration, and the success of dental implantation depends on adequate formation of this intimate bone-to-implant contact. The application of heat during the drilling procedure leads to a rise in intraosseous temperature at the prospective implant site, which may result in various complications. The purpose of the present study was to compare the ability of thermocouples and infrared thermography to detect changes in intraosseous temperature during dental implant site preparation. MATERIALS AND METHODS: Standardized bovine costae bone blocks were used to simulate the cortical bone of the human mandible. Steel implant form drills with a diameter of 3.0 mm were used. Two types of irrigation systems were used (external cooling only and combined internal and external cooling). Drilling was performed at a constant speed (1,200 rpm). Changes in intraosseous temperature were evaluated using Type T Cu-CuNi thermocouples and an infrared thermography camera system at contact pressures of 5 and 20 N. RESULTS: Infrared thermography detected significantly greater increases in intraosseous temperature (ΔT) than thermocouples for all tested combinations of cooling system and contact pressure (P ≤ .0001). CONCLUSION: These results suggest that thermography more accurately reflects intraosseous temperature changes during implant site preparation than thermocouples.

Enhancing bone regeneration by combining mesenchymal stem cell sheets with ß-TCP/COL-I scaffolds.

The combination of bone marrow-derived mesenchymal stem cells (BMSCs) and biological scaffolds has been demonstrated to be a promising strategy for bone regeneration. However, this method does not result in satisfactory bone regeneration, because the BMSCs are dispersed in the biological scaffolds. The current study developed a new bone regeneration system, which combines synthetic porous three-dimensional scaffolds of ß-TCP/COL-I composite with cultured osteogenic sheets of BMSCs. Activity of alkaline phosphatase (ALP), a marker of bone regeneration, was assayed in vitro using enzyme-linked immunosorbent assays and quantitative real-time polymerase chain reaction. In vivo bone regeneration was assayed in male nude mice. The study samples were BMSC sheet, scaffold/scattered BMSCs, scaffold/BMSC sheet, and scaffold alone. The samples were implanted dorsally in the mice. In vitro analysis showed that ß-TCP/COL-I scaffold combined with BMSC sheets significantly upregulated both gene expression and protein levels of ALP, osteocalcin, and osteopontin. Histological and micro-computed tomography showed that the only implants that demonstrated new bone formation after 4 weeks were scaffold/BMSC sheet implants. These results underscore the crucial requirement of a synergistic effect of ß-TCP/COL-I scaffolds and BMSC sheets. This could be a promising novel strategy for bone tissue engineering. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2037-2045, 2018.

Wear of composite resin veneering materials and enamel in a chewing simulator.

OBJECTIVES: The purpose of this in vitro study was to evaluate the wear of six composite resins for the veneering of crowns compared with the wear of human and bovine enamel, tested in a dual-axis chewing simulator. METHODS: Eight specimens of six different composite resins (Targis I+II, Solidex, BelleglassHP, Estenia, Solidex) and of human and bovine enamel were prepared. Steatite ceramic balls served as antagonistic specimens. Specimens were dynamically loaded in a dual-axis chewing simulator with 49 N up to 1,200,000 loading cycles with additional thermal cycling between 5 and 55 degrees C. After 120,000, 240,000, 480,000, 840,000 and 1,200,000 loading cycles, an impression of the specimens' surface and the antagonistic specimen was taken using a polyvinylsiloxane impression material. The substance loss at the surface was measured with computer-aided laser profilometry. Data were analyzed using ANOVA and the Tukey test. RESULTS: The wear of the ultra fine compact filled composite resins Solidex and BelleglassHP was not statistically significantly different from that of human enamel. The other composite resins and bovine enamel showed a wear statistically significantly higher than human enamel. SIGNIFICANCE: Comparing six composite resins for the veneering of crowns, ultra fine compact filled composite resins BelleGlassHP and Solidex showed a wear not significantly different from the wear of human and bovine enamel.

Impact of Cleaning Procedures on Adhesion of Living Cells to Three Abutment Materials.

PURPOSE: To test the adhesion properties of live gingival fibroblasts to three different implant abutment materials after five different cleaning procedures. MATERIALS AND METHODS: Highly polished discs of lithium disilicate (LS), zirconium dioxide (Zr), and titanium alloy (Ti) were fabricated. The specimens were cleaned by one of five different methods: steam (S), argon plasma (AP), ultrasound and disinfection (UD), ultrasound and sterilization in an autoclave (UA), or photofunctionalization with high-intensity ultraviolet light (PF). Cell detachment force (adhesion) was measured by single-cell force spectroscopy, which is a method to quantify cell adhesion at the single cell level. Data were statistically analyzed using parametric tests (analysis of variance [ANOVA], t tests). RESULTS: Cell detachment forces in the low nN regime were recorded in all experiments. Significant differences in cell adhesion on the different materials were found as a function of the cleaning method (P ≤ .0001). For LS abutments, no significant differences between the cleaning methods could be found (P > .05). For Zr specimens, the AP method showed the highest cell detachment forces, followed by UD, PF, S, and UA (S/UD, S/UA, S/PF, AP/UD, and UD/PF were not significantly different from each other). For Ti abutments, UD showed the highest cell detachment forces, followed by S, AP, and UA/PF (S/UD, S/UA, S/PF, AP/U, and UA/PF were not significantly different from each other). CONCLUSION: All cleaning methods provided comparable cell detachment forces for LS abutments. AP/PF or ultrasonic cleaning were the most suitable methods for strong cell adhesion on Zr. UD provided the best cell adhesion for Ti.

BMP-2 plasmid DNA-loaded chitosan films - A new strategy for bone engineering.

OBJECTIVES: Bone defects are common in every area of medicine and remain a clinical challenge. Tissue engineering has led to promising new strategies in accelerating bone repair. Bone morphogenetic proteins (BMPs) play crucial roles in bone regeneration, but are required in supra-physiological doses, which are expensive and produce severe side effects. METHODS: To address these issues, we prepared BMP-2 plasmid DNA-loaded chitosan films, and examined their effects on mouse osteoblast-like MC3T3-E1 cell morphology, proliferation, and runt-related transcription factor 2 (RUNX2) expression. In vivo testing was performed using calvarial critical-sized defects and histomorphometry in 36 Sprague-Dawley rats. Unloaded chitosan films and empty defects served as controls. RESULTS: In contrast to the controls, cells grown on BMP-2 plasmid DNA-loaded chitosan films had well established filopodia and lamellipodia, significantly higher proliferation 2, 4, and 6 days post-seeding (P ≤ 0.05), and higher nuclear RUNX2 expression. In vivo, new bone growth was significantly greater in the BMP-2 group than in the control groups at 4, 8, and 12 weeks (P ≤ 0.01). CONCLUSIONS: Based on our study findings, BMP-2 plasmid DNA-loaded chitosan films provide an effective strategy for GBR, combining cellular compatibility with biocapability in vivo.