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Statement of problem Little is known about whether the misfit level of implant-supported screw-retained prostheses can be tolerated when different combinations of engaging and nonengaging titanium bases are used. Purpose The purpose of this in vitro study was to simulate prosthetic workflow distortions (horizontal and vertical) and to evaluate the fit (passive and active) of 2-implant-supported screw-retained zirconia frameworks with 3 different combinations of abutments: both engaging, engaging and nonengaging, and both nonengaging. Material and methods The fit of both engaging (n=10), engaging and nonengaging (n=10), and both nonengaging (n=10) 2-implant-supported zirconia frameworks was evaluated on control and definitive casts simulating 50-, 100-, and 150-μm vertical and 35-, 70-, 100-μm horizontal misfit levels. Stereomicroscopy was used to assess the passive fit (1 screw tightened) and active fit (both screws tightened) of the zirconia frameworks. Vertical deviations in the implant and abutment connection (the implant-abutment gap measured vertically) between the implant platform and reference line on the titanium base were measured. The Kruskal-Wallis and Mann-Whitney U tests (α=.05) were used to compare different implant-supported zirconia specimens on each definitive cast. Results When 1 screw was tightened, both engaging specimens had higher vertical deviations (ranging from 40.1 to 131.1 μm) in 35- and 70-μm horizontal misfit levels, as compared with engaging and nonengaging (19.8 to 85.1 μm) and both nonengaging (6.6 to 14.3 μm) specimens. Comparing medians of the 100-μm misfit in horizontal (engaging and nonengaging 140.4 μm; both nonengaging 151.6 μm) and vertical (engaging and nonengaging 49.8 μm; both nonengaging 42.6 μm) directions, the horizontal misfits caused larger vertical deviations. When both screws were tightened in 50-, 100-, and 150-μm vertical misfit groups, the vertical gap increase in the engaging and nonengaging specimens was significantly higher than that in both the nonengaging specimens (P

OBJECTIVES: The main objective of the study was to compare the accuracy of full-arch digital implant impressions for fixed dental prosthesis under in vitro and in vivo conditions. MATERIALS AND METHODS: Eight patients (five women and three men) with at least one edentulous arch and with 4-6 osseointegrated implants participated in this study. For each edentulous arch (n = 10), experimental screw-retained titanium bar with attached four scan bodies was fabricated. The bar containing four scan bodies was screw-retained intraorally on implants and scanned with Trios 3 intraoral scanner eight times (IOS group, in vivo). Then, the bar was attached to the master cast and scanned eight times again with the same intraoral scanner (MIOS group, in vitro). Finally, the bar with scan bodies was scanned 8 times with a laboratory scanner (reference). Precision and trueness were calculated for 3 distances and 3 angles between the scan bodies (1-2, 1-3, and 1-4) in IOS and MIOS groups. RESULTS: Precision and trueness for the largest distance (1-4) were found to be 44 ± 18 µm and 32 ± 19 µm for the IOS group and 31 ± 16 µm and 30 ± 14 µm for MIOS group, respectively. Precision and trueness for the angle between the most distant scan bodies (1-4) were 0.22 ± 0.14° and 0.18 ± 0.10° for the IOS group and 0.16 ± 0.11° and 0.07 ± 0.05° for MIOS group, respectively. CONCLUSIONS: Intraoral conditions moderately affected the precision and trueness of Trios 3 (3Shape) intraoral scanner. Results of in vitro accuracy studies cannot be directly transferred to the clinical field.

UV photofunctionalization of Zirconia-based materials for abutment fabrication is a promising approach that might influence the formation of a sound peri-implant seal, thus promoting long-term soft and hard tissue implant integration. This study aimed to evaluate the effect of UV treatment of test specimens made by two different ZnO2-based ceramic materials on the hydrophilicity, cell cytotoxicity, and proliferation of human gingival fibroblasts (HGFs). Two Zirconia-based materials, high-translucent and ultra-translucent multi-layered Zirconia (Katana, Kuraray Noritake, Japan), were used to prepare a total of 40 specimens distributed in two equally sized groups based on the material (n = 20). The same surface finishing protocol was applied for all specimens, as suggested by the manufacturer. Half the specimens from each group were treated with UV-C light for 48 h. Water contact angle (WCA), fibroblast cytotoxicity, and proliferation were investigated. The WCA values for the high-translucent Zirconia ranged from 69.9° ± 6.4° to 73.7° ± 13.9° for the treated/non-treated specimens and from 79.5° ± 12.8° to 83.4° ± 11.4° for the ultra-translucent multi-layered Zirconia, respectively. However, the difference was insignificant (F(16) = 3.50, p = 0.292). No significant difference was observed for the fibroblast cytotoxicity test. The results for proliferation revealed a significant difference, which was material-dependent (F(8) = 9.58, p = 0.005). We found that UV surface photofunctionalization of ZrO2-based materials alters the human gingival fibroblast cell viability, which might produce favourable results for cell proliferation.

To facilitate artificial bone construct integration into a patient's body, scaffolds are enriched with different biologically active molecules. Among various scaffold decoration techniques, coating surfaces with cell-derived extracellular matrix (ECM) is a rapidly growing field of research. In this study, for the first time, this technology was applied using primary dental pulp stem cells (DPSCs) and tested for use in artificial bone tissue construction.Rat DPSCs were grown on three-dimensional-printed porous polylactic acid scaffolds for 7 days. After the predetermined time, samples were decellularized, and the remaining ECM detailed proteomic analysis was performed. Further, DPSC-secreated ECM impact to mesenchymal stromal cells (MSC) behaviour as well as its role in osteoregeneration induction were analysed.It was identified that DPSC-specific ECM protein network ornamenting surface-enhanced MSC attachment, migration and proliferation and even promoted spontaneous stem cell osteogenesis. This protein network also demonstrated angiogenic properties and did not stimulate MSCs to secrete molecules associated with scaffold rejection. With regard to bone defects, DPSC-derived ECM recruited endogenous stem cells, initiating the bone self-healing process. Thus, the DPSC-secreted ECM network was able to significantly enhance artificial bone construct integration and induce successful tissue regeneration.DPSC-derived ECM can be a perfect tool for decoration of various biomaterials in the context of bone tissue engineering.

The better understanding of the clinically important behavioral features of new instrument systems has an important significance for the clinical endodontics. This study aimed to investigate the shaping and centering ability as well as cyclic fatigue resistance of HyFlex CM (CM), HyFlex EDM (EDM) and EdgeFile (EF) thermally treated nickel&ndash, titanium (NiTi) endodontic instrument systems. Sixty curved root canals of the mesial roots of mandibular molars were randomly assigned into three groups (n = 20) and shaped using CM, EDM and EF files up to the size 40 and taper 04 of the instruments. &micro, CT scanning of the specimens before and after preparation was performed and the morphometric 2D and 3D parameters were evaluated in the apical, middle and coronal thirds of root canals. In each group, 40.04 instruments (n = 20) were subjected to the cyclic fatigue resistance test in artificial root canals at 37 &deg, C temperature until fractures occurred, and the number of cycles to failure (NCF) was calculated. The fractographic analysis was performed using a scanning electron microscope, evaluating topographic features and surface profiles of the separated instruments. The one-way analysis of variance with post hoc Tuckey&rsquo, s test was used for statistical analysis of the data, the significance level was set at 5%. All systems prepared the comparable percentage of root canal surface with the similar magnitude of canal transportation in all root thirds (p &gt, 0.05), but demonstrated significantly different resistance to cyclic fatigue (p &lt, 0.05). The most resistant to fracture was EF, followed by EDM and CM. The length of the fractured fragments was not significantly different between the groups, and fractographic analysis by SEM detected the typical topographic features of separated thermally treated NiTi instrument surfaces.

Background The literature has not yet validated the use of intraoral scanners (IOSs) for full-arch (FA) implant impression. Hence, the aim of this in vitro study was to assess and compare the trueness of 12 different IOSs in FA implant impression. Methods A stone-cast model of a totally edentulous maxilla with 6 implant analogues and scanbodies (SBs) was scanned with a desktop scanner (Freedom UHD®) to capture a reference model (RM), and with 12 IOSs (ITERO ELEMENTS 5D®; PRIMESCAN® and OMNICAM®; CS 3700® and CS 3600®; TRIOS3®; i-500®; EMERALD S® and EMERALD®; VIRTUO VIVO® and DWIO®; RUNEYES QUICKSCAN®). Ten scans were taken using each IOS, and each was compared to the RM, to evaluate trueness. A mesh/mesh method and a nurbs/nurbs method were used to evaluate the overall trueness of the scans; linear and cross distances between the SBs were used to evaluate the local trueness of the scans. The analysis was performed using reverse engineering software (Studio®, Geomagics; Magics®, Materialise). A statistical evaluation was performed. Results With the mesh/mesh method, the best results were obtained by CS 3700® (mean error 30.4 μm) followed by ITERO ELEMENTS 5D® (31.4 μm), i-500® (32.2 μm), TRIOS 3® (36.4 μm), CS 3600® (36.5 μm), PRIMESCAN® (38.4 μm), VIRTUO VIVO® (43.8 μm), RUNEYES® (44.4 μm), EMERALD S® (52.9 μm), EMERALD® (76.1 μm), OMNICAM® (79.6 μm) and DWIO® (98.4 μm). With the nurbs/nurbs method, the best results were obtained by ITERO ELEMENTS 5D® (mean error 16.1 μm), followed by PRIMESCAN® (19.3 μm), TRIOS 3® (20.2 μm), i-500® (20.8 μm), CS 3700® (21.9 μm), CS 3600® (24.4 μm), VIRTUO VIVO® (32.0 μm), RUNEYES® (33.9 μm), EMERALD S® (36.8 μm), OMNICAM® (47.0 μm), EMERALD® (51.9 μm) and DWIO® (69.9 μm). Statistically significant differences were found between the IOSs. Linear and cross distances between the SBs (local trueness analysis) confirmed the data that emerged from the overall trueness evaluation. Conclusions Different levels of trueness were found among the IOSs evaluated in this study. Further studies are needed to confirm these results.

Topography of the scaffold is one of the most important factors defining the quality of artificial bone. However, the production of precise micro- and nano-structured scaffolds, which is known to enhance osteogenic differentiation, is expensive and time-consuming. Meanwhile, little is known about macro-patterns (larger than cell diameter) effect on cell fate, while this kind of structures would significantly facilitate the manufacturing of artificial skeleton. Therefore, this research is focused on polylactic acid scaffold's macro-pattern impact on rat's dental pulp stem cells (DPSCs) morphology, proliferation, and osteogenic differentiation. For this study, two types of scaffolds were 3D printed: wavy and porous. Wavy scaffolds consisted of 188 μm wide joined threads, meaning that cells might have been curved on the filament as well as compressed in the groove. Porous scaffolds were designed to avoid groove formation and consisted of 500 μm threads, arranged in the woodpile manner, forming 300 μm diameter pores. We found that both macro-surfaces influenced DPSC morphology compared to control. As a consequence, enhanced DPSC proliferation and increased osteogenic differentiation potential was registered in cells grown on these scaffolds. Finally, our results showed that the construction of an artificial bone did not necessarily require the precise structuring of the scaffold, because both types of macro-topographic PLA scaffolds were sufficient enough to induce spontaneous DPSC osteogenic differentiation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 174-186, 2019.

BACKGROUND Long-term success of implant-supported restorations can be affected by the accuracy of the prosthodontic workflow which may differ between conventional and digital techniques. PURPOSE The purpose was to compare the fit of two-implant-supported restorations, fabricated using conventional and digital workflows and to assess the influence of distance and angulation between the implants on the passive fit of the prosthesis. The SR test was selected to evaluate the fit of two-implant-supported zirconia restorations. MATERIALS AND METHODS Forty-eight zirconia two-implant-supported restorations were fabricated according to conventional (group C, n = 24) and digital (group D, n = 24) workflows. The SR parameter was calculated as a difference of rotation angles of each screw in passive and nonpassive situations. SR values between groups C and D were compared by performing measurements intraorally, on master and control casts. RESULTS SR intraorally in group C (16.25 ± 15.52°) was higher than it was in group D (13.85 ± 10.78°), but the difference was not statistically significant (P = .557). While measuring SR on the master cast, group C SR (6.04 ± 7.43°) had lower values than group D (13.12 ± 13.86°) (P = .0039). No statistically significant correlations were found between SR measurements and inter-implant distance or angulation. Restorations with inter-implant angle higher than 10° differed significantly from those with less than 10° angulation. CONCLUSIONS Digital restorations had a better fit on the control cast, which was used as a reference in this study. Angulation of more than 10° between the implants could negatively affect the passive fit of the digitally fabricated restorations intraorally.

3D printing of polylactic acid (PLA) and hydroxyapatite (HA) or bioglass (BG) bioceramics composites is the most promising technique for artificial bone construction. However, HA and BG have different chemical composition as well as different bone regeneration inducing mechanisms. Thus, it is important to compare differentiation processes induced by 3D printed PLA + HA and PLA + BG scaffolds in order to evaluate the strongest osteoconductive and osteoinductive properties possessing bioceramics. In this study, we analysed porous PLA + HA (10%) and PLA + BG (10%) composites' effect on rat's dental pulp stem cells fate in vitro. Obtained results indicated, that PLA + BG scaffolds lead to weaker cell adhesion and proliferation than PLA + HA. Nevertheless, osteoinductive and other biofriendly properties were more pronounced by PLA + BG composites. Overall, the results showed a strong advantage of bioceramic BG against HA, thus, 3D printed PLA + BG composite scaffolds could be a perspective component for patient-specific, cheaper and faster artificial bone tissue production.

In complex clinical conditions when physiological bone regeneration is insufficient, there is a need to develop synthetic material-based scaffolds. The morphologic properties of porous scaffolds are of crucial importance. The dimensional accuracy of 3D printed scaffolds can be affected by a variety of factors.Three groups of 3D printed scaffolds were investigated: PLA1 (pure polylactic acid) printed with an FDM Ultimaker Original printer, PLA2 and composite PLA/hydroxyapatite (PLA/HAp) scaffolds printed with a Pharaoh XD 20. PLA/HAp filament was created with hot-melt extrusion (HME) equipment. The morphology of the prepared scaffolds was investigated with SEM, micro-CT and superimposition techniques, gravimetric and liquid displacement methods.Layer heights of PLA1 scaffolds varied the most. PLA1 scaffold volume statistically significantly differed from PLA2 (p 0.001) and PLA/HAp (p 0.01) groups. Filament composition had no effect on the volumes of the scaffolds printed with the Pharaoh XD 20 printer (p 0.05). The total porosity of printed PLA/HAp scaffolds deviated the least from the original STL model.This study showed that PLA/10% HAp filament fabricated with HME and printed with FFF 3D printer produced equal or even better accuracy of printed scaffolds than scaffolds printed with pure PLA filament. Further research is needed to analyze the effect of HAp on 3D scaffold morphology, accuracy, mechanical and biologic properties.

Purpose The newest technologies for digital implant impression (DII) taking are developing rapidly and showing acceptable clinical results. However, scientific literature is lacking data from clinical studies about the accuracy of DII. The aim of this study was to compare digital and conventional dental implant impressions (CII) in a clinical environment. Materials and methods Twenty-four fixed zirconia restorations supported by 2 implants were fabricated using conventional open-tray impression technique with splinted transfers (CII group) and scan with Trios 3 IOS (3Shape) (DII group). After multiple verification procedures, master models were scanned using laboratory scanner D800 (3Shape). 3D models from conventional and digital workflow were imported to reverse engineering software and superimposed with high resolution 3D CAD models of scan bodies. Distance between center points, angulation, rotation, vertical shift, and surface mismatch of the scan bodies were measured and compared between conventional and digital impressions. Results Statistically significant differences were found for: a) inter-implant distance, b) rotation, c) vertical shift, and d) surface mismatch differences, comparing DII and CII groups for mesial and dist al implant scan bodies (P≤.05). Conclusion Recorded linear differences between digital and conventional impressions were of limited clinical significance with two implant-supported restorations.

Dental implant abutment and prosthetic materials, their surface treatment, and cleaning modalities are important factors for the formation of a peri-implant soft tissue seal and long-term stability of bone around the implant. This study aimed to investigate the influence of a polymeric material surface cleaning method on the surface roughness, water contact angle, and human gingival fibroblasts (HGF) proliferation. Polymeric materials tested: two types of milled polymethylmethacrylate (PMMA-Ker and PMMA-Bre), three-dimensionally (3D) printed polymethylmethacrylate (PMMA-3D), polyetheretherketone (PEEK), and polyetherketoneketone (PEKK). Titanium (Ti) and zirconia oxide ceramics (ZrO-HT) were used as positive controls. A conventional surface cleaning protocol (CCP) was compared to a multi-step research cleaning method (RCP). Application of the RCP method allowed to reduce Sa values in all groups from 0.14&ndash, 0.28 &micro, m to 0.08&ndash, 0.17 &micro, m (p &lt, 0.05 in PMMA-Ker and PEEK groups). Moreover, the water contact angle increased in all groups from 74&ndash, 91&deg, to 83&ndash, 101&deg, (p &lt, 0.05 in the PEKK group), except ZrO-HT&mdash, it was reduced from 98.7 &plusmn, 4.5&deg, to 69.9 &plusmn, 6.4&deg, 0.05). CCP resulted in higher variability of HGF viability after 48 and 72 h. RCP application led to higher HGF viability in PMMA-3D and PEKK groups after 48 h, but lower for the PMMA-Ker group (p &lt, 0.05). After 72 h, no significant differences in HGF viability between both cleaning methods were observed. It can be concluded that the cleaning method of the polymeric materials affected surface roughness, contact angle, and HGF viability at 48 h.

Topography of the scaffold is one of the most important factors defining the quality of artificial bone. However, the production of precise micro- and nano-structured scaffolds, which is known to enhance osteogenic differentiation, is expensive and time-consuming. Meanwhile, little is known about macro-patterns (larger than cell diameter) effect on cell fate, while this kind of structures would significantly facilitate the manufacturing of artificial skeleton. Therefore, this research is focused on polylactic acid scaffold's macro-pattern impact on rat's dental pulp stem cells (DPSCs) morphology, proliferation, and osteogenic differentiation. For this study, two types of scaffolds were 3D printed: wavy and porous. Wavy scaffolds consisted of 188 μm wide joined threads, meaning that cells might have been curved on the filament as well as compressed in the groove. Porous scaffolds were designed to avoid groove formation and consisted of 500 μm threads, arranged in the woodpile manner, forming 300 μm diameter pores. We found that both macro-surfaces influenced DPSC morphology compared to control. As a consequence, enhanced DPSC proliferation and increased osteogenic differentiation potential was registered in cells grown on these scaffolds. Finally, our results showed that the construction of an artificial bone did not necessarily require the precise structuring of the scaffold, because both types of macro-topographic PLA scaffolds were sufficient enough to induce spontaneous DPSC osteogenic differentiation. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 174-186, 2019.

The study aimed to 1) evaluate the cytotoxicity of luting cements: Hoffmann's Zinc Phosphate (Hoffmann's ZP), GC Fuji Plus Resin Modified Glass Ionomer (Fuji Plus RMGI) and 3M ESPE RelyX Unicem Resin Cement (RelyX Unicem RC) and 2) test if pre-washing reduces the cements' cytotoxicity. In vitro human gingival fibroblast (HGF) culture model was chosen. The cytotoxicity was evaluated by MTT test, the cell viability -by staining the cells with AO/EB dye mixture. The means±SD of Cell Survival Ratio (CSR%) were compared among different cement types under two testing conditions, with or without cement pre-washing. The CSR%s were compared by ANOVA and linear multiple regression (LMR). Hoffmann's ZPC was less cytotoxic, while Fuji Plus RMGIC and RelyX Unicem RC were more cytotoxic (ANOVA, p

The aim of this study was to evaluate wear effects on overdenture resilient attachments. Six commercially available attachments were investigated: ERA orange and white (EO and EW), Locator pink, white and blue (LRP, LRW and LRB) and OP anchor (OP). Five specimens were used for wear simulation while other two specimens served as controls. Fifteen thousands insertion-removal cycles were simulated. Dimensional changes and surface characteristics were evaluated using light microscopy and SEM, respectively. Sudden decrease of retentive force was characteristic for EO and EW attachments. Retentive force of Locator attachments fluctuated throughout the wear simulation period. Dimensional changes and surface wear was more expressed on plastic cores than on plastic rings of attachment males. Based on SEM analysis, some of the specimens obtained smoother surface after wear simulation. Mechanism of retention loss of resilient overdenture attachments can be only partially explained by dimensional changes and surface alterations.

The study aimed to 1) evaluate the cytotoxicity of luting cements: Hoffmann's Zinc Phosphate (Hoffmann's ZP), GC Fuji Plus Resin Modified Glass Ionomer (Fuji Plus RMGI) and 3M ESPE RelyX Unicem Resin Cement (RelyX Unicem RC) and 2) test if pre-washing reduces the cements' cytotoxicity. In vitro human gingival fibroblast (HGF) culture model was chosen. The cytotoxicity was evaluated by MTT test, the cell viability -by staining the cells with AO/EB dye mixture. The means±SD of Cell Survival Ratio (CSR%) were compared among different cement types under two testing conditions, with or without cement pre-washing. The CSR%s were compared by ANOVA and linear multiple regression (LMR). Hoffmann's ZPC was less cytotoxic, while Fuji Plus RMGIC and RelyX Unicem RC were more cytotoxic (ANOVA, p0.001). The type of cement and cement pre-washing jointly explained 90% of cell survival (LMR, p0.001, adjusted squared R=0.889). The commonly used luting cements such as Hoffmann's ZP, Fuji Plus RMGI and RelyX Unicem RC may have a cytotoxic potential.

Transferring the implant position from the mouth to the definitive cast is one of the most critical steps in implant prosthodontics. To achieve a passive fit of the prosthesis, an accurate implant impression is crucial because discrepancies can induce both biologic and technical complications. Analysis of available research data suggests that a direct (pick-up) impression technique with splinted copings is the technique of choice, particularly for multiple implants. However, the traditional method of splinting the copings with autopolymerizing acrylic resin is a technique-sensitive and time- consuming procedure. This report describes a straightforward method of splinting impression copings with light-polymerizing acrylic resin, with minimal amount of autopolymerizing acrylic resin. The method also can be used to verify splinting accuracy.

The aim of this preliminary laboratory study was to evaluate the effects of 5- and 25-degree implant angulations in simulated clinical casts on an impression's accuracy when using different impression materials and tray selections. A convenience sample of each implant angulation group was selected for both open and closed trays in combination with one polyether and two polyvinyl siloxane impression materials. The influence of material and technique appeared to be significant for both 5- and 25-degree angulations (P.05), and increased angulation tended to decrease impression accuracy. The open-tray technique was more accurate with highly nonaxially oriented implants for the small sample size investigated.

To assess qualitative and quantitative cytotoxicity effect on permanent prosthetic materials to human gingival fibroblasts.Human gingival tissues were collected (with informed consent) from patients undergoing periodontal surgical procedures and fibroblasts were cultured in vitro. Cell type was determined by performing proteomic analysis. Selected prosthetic materials including titanium, feldspathic ceramic, gold and chrome-cobalt alloy specimens (5×2 mm) were fabricated. The toxicity of prepared specimens was tested by exposing them to cell culture medium for 48, 72, 96 and 120 hours at 37°C under sterile conditions. Cell viability was estimated using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. The data concerning cell viability were statistically analyzed using two-way ANOVA test and Tukey multiple comparison test.Results obtained after 48 hours showed no toxic effect of titanium compared to control group. Cytotoxic effect was observed in gold alloy and feldspathic ceramic, however, it was not significant compared to control group. Chrome-cobalt alloy significantly reduced cell viability compared to control group (p≤0.001). Cytotoxicity diminished with increasing incubation time of specimens. After 120 hours of incubation all tested materials, except chrome-cobalt alloy, had no cytotoxicity.Titanium proved to be non-toxic. Gold alloy and feldspathic ceramic had short-term cytotoxic effect. Chrome-cobalt alloy had highest cytotoxic effect on fibroblast cells.

The main objective was to investigate the effects of different polishing techniques on the color stability of provisional prosthetic materials upon exposure to different staining agents by mimicking the oral environment in vitro. Fifty-six cylindrical specimens were prepared for each type of material: bis-acryl and light-polymerized composite resins, and methyl methacrylate- and ethyl methacrylatebased resins. The specimens were polished using seven different polishing techniques and then immersed in four different staining agents. Color was measured with a spectrophotometer before and after immersion, and color changes (DeltaE) were calculated. The effects of the type of provisional material, polishing procedure, staining agent, and their interactions on color stability were significant (p

OBJECTIVES. To investigate repolishing effect of stained provisional prosthetic materials in vitro. METHODS. Thirty two cylindrical specimens (10 x 2 mm) were prepared for each of light-polymerized composites (Revotek LC, Rx-Create), bis-acryl composites (Structur Premium, Protemp Garant3, Luxatemp Fluorescence), methyl-methacrylate (UnifastTRAD) and ethyl-methacrylate (DentalonPlus) based provisional material using a mould. The specimens were divided into 4 groups (n=8) according to different repolishing techniques. The specimens were stored for 24 hours at 37 degrees C in distilled water, and then transferred into 4 different staining agents. The colour was measured with a spectrophotometer (Vita Easyshade) before exposure and after repolishing procedures, and colour changes (DeltaE) were calculated.three-way ANOVA, Tukey HSD post-hoc test (p0.05). RESULTS. The influence of type of provisional material, polishing procedure, food colorants and combinations of them on colour change was significant (p0.05). After the repolishing procedures, all the specimens stored in distilled water achieved an unnoticeable colour change (DeltaE3.7), except Dentalon Plus, Rx Create, Unifast TRAD. A similar tendency was observed in artificial food colourant solution following subsequent repolishing of the specimens. As for the red wine, all repolished specimens attained unnoticeable colour change (DeltaE3.7), except Dentalon Plus using Rx polishing paste, Enhance polishing set or repeated glazing procedure. CONCLUSION. Repolishing was found to be an effective way to improve aesthetic appearance for provisional prosthetic materials by partially removing staining observed on the surface of the restorations.

The aims of the presented study were to define the fracture rate of implant-supported metal-ceramic restorations delivered in private practice, and to identify if a restoration's contact during eccentric mandible movements has any influence on ceramic fracture rates.Within the period from 2005 to 2008, 251 patients, namely 105 men (42%) and 146 women (58%), received 775 dental implants which later were restored with metal-ceramic restorations. Data was gathered and analyzed in the form of a specially-designed electronic questionnaire. In total, 251 patients were rehabilitated with 350 prostheses consisting of 151 single crowns, 208 fixed partial dentures of various extents and 21 full-arch restorations. The method for retention of prostheses included cement-, screw-, or hybrid cement-screw retained prosthetic devices. The patients were recalled and examined for the presence of mechanical complications, namely ceramic fractures. Fractures were distinguished as adhesive or co-adhesive. The follow-up time was registered.The mean ceramic fracture rate was 6.7%, as fracture occurred in 24 restorations. In the single crown group, the fracture rate was 1.3%, in the fixed partial denture division it was 6.7%, and the full-arch metal-ceramic restorations experienced 38.1% chipping. The mean follow-up period of prostheses was 9.5 months, ranging from 1 to 42 months. The analysis revealed that 66 prostheses had contact in protrusive and/or lateral mandibular movements, constituting 17.4% of all restorations; while 13 restorations had ceramic fractures, composing 19.7% of all guiding prostheses.Within the limitations of this trial, it can be noted that ceramic veneer fracture rate was 6.7% in 380 restorations, and a conclusion that a restoration's contact during eccentric excursions may significantly enlarge fracture rates can be made.

Implant loading time is considered to influence the treatment outcomes. Number of experimental studies have shown that implant loading up to 3 months can produce equally satisfactory results. However, research results in this area are not consistent. The purpose of the study was to investigate the influence of conventional and early loading of two-implant supported mandibular overdentures on treatment outcomes.The articles from 1985 to 2007 in English related to the topic were identified. Totally 221 (214 online and 7 printed) primary articles were detected. Eight articles were selected for data extraction. Implant survival and success rates, periimplant parameters, prosthetic maintenance and patient satisfaction were considered.Implant success rate ranged from 83% to 100% in conventional loading group and from 71% to 100% in early loading group. During the first year in conventional group, the marginal bone loss ranged from 0.35 to 0.91 mm, during the second year--from zero to 0.2 mm, whereas in early loading group these intervals were 0.12-1 mm and 0-0.15 mm, respectively. Comparing averaged probing depth values at different time periods, it could be noticed that around conventionally loaded implants probing depth slightly decreased (from 1.62 mm to 1.56 mm), while around early loaded implants--increased from 1.7 mm to 1.82 mm.Considering implant success rates and peri-implant parameters early loading protocol produces equal outcomes as with conventional loading. More well designed studies are needed to further substantiate the early loading protocol.

A traditional concept is that apical periodontitis is the result of pathogenic effects of the microorganisms colonizing the root canal system and the response of the host defence system. The composition of the microflora of root canals differs in primary endodontic treatment and retreatment cases. Persistent disease in the periapical region after root canal treatment presents a more complex situation as it was thought earlier. Scientific evidence indicates that unsatisfactory outcome of cases in which treatment has followed the highest technical standards mainly is associated with microbial factors, comprising extraradicular and/or intraradicular infections.

UNLABELLED The aims of this study were: (i) to evaluate and compare retention of two-teeth (implant) supported mandibular overdenture with either stud or magnetic attachments during linear (axial) and rotational (paraxial) dislodgements; (ii) to compare retentive properties before and after wear simulation. The test group consisted of five magnetic and four stud overdenture attachments (n = 12 specimens for each attachment type). Retention in axial direction was evaluated on one-tooth (implant) model by measuring maximum retentive force (N) and range of retention (mm) during the linear dislodgement. Retention in the paraxial direction was evaluated on mandibular-overdenture model by measuring the maximum retentive force (N) during three types of rotational dislodgements - anterior, lateral and posterior. The minimum number of cycles required to simulate wear was determined by special wear test. Afterwards, the wear was simulated in the test group, and retention in axial and paraxial directions was measured again. STATISTICAL ANALYSIS one-way anova, Scheffe post hoc and paired-samples t-tests (P < 0.05). Initially, studs had higher retention (4-11 N) than magnets (4.5-6 N) in axial direction. After the wear simulation, it had decreased from 76% to 48% for some of the studs and had become similar to the retention of magnetic attachments. Magnets had lower retention range (0.2-0.3 mm) than studs (0.5-1.1 mm). Studs provided similar or higher retention in paraxial directions than magnetic attachments both before and after wear simulation. Retentive properties of magnets decreased mostly with posterior rotational dislodgement. Retentive properties of stud overdenture attachments were less constant.

Summary form only given. We present direct laser fabrication of 3D microstructured scaffolds consisting out of a few polymeric materials owning different biological properties. Direct laser writing in photo/thermo-sensitive materials using ultra short light pulses of high repetition laser provides unmatched flexibility in controllable 3D microstructuring in a variety of bio-materials [1], as well as manufacturing throughput empowers overall structure size of more than 1 mm3, making it an attractive method to fabricate scaffolds for cell studies and tissue engineering applications [2, 3]. In this work, a femtosecond direct laser writing system was supplemented by a machine vision [4] to relocate the sample between different fabrication steps.