Fracture load of 4-unit interim fixed partial dentures using 3D-printed and traditionally manufactured materials.

STATEMENT OF PROBLEM: How the fracture strength of recently introduced 3-dimensionally (3D) printed interim materials compares with that of conventional materials is unclear. PURPOSE: The purpose of this in vitro study was to compare the fracture load of 4-unit interim fixed partial dentures made from 3 different materials before and after mastication simulation. MATERIAL AND METHODS: Based on a master model of a 4-unit fixed partial denture with maxillary left first premolar and second molar abutment teeth, interim restorations were fabricated from 3 different materials (3D-printed, Temporary CB Resin, milled, PMMA for brain, and manually manufactured, Luxatemp Plus). The fixed partial dentures (n=30 for each material) were cemented on 3D-printed model abutment teeth that were connected via a thin latex layer to a polyurethane base block. The fracture load of 15 fixed partial dentures of each material was tested without aging. Another 15 fixed partial dentures of each material were tested after thermomechanical aging. RESULTS: The mean fracture load was between 186 N and 661 N, and all materials showed significant lower fracture loads after aging. Before and after aging (before/after ±standard deviation) milled (661 ±59/568 ±52 N) achieved the highest loads before manually manufactured (621 ±100/478 ±96 N) and 3D-printed (294 ±83/186 ±70). CONCLUSIONS: The 3D-printed interim restoration material and the inherent manufacturing process show significant lower fracture loads than the tested alternatives. However, as the influence of geometric differences could not be quantified, whether this remains true after correcting for geometric differences remains unclear. For the tested interim materials, thermocycling and mastication simulation significantly reduced fracture loads over time, even at loads as low as 50 N.

Antimicrobial agents in dental restorative materials: Effect on long-term drug release and material properties.

The present study reports on the long-term drug release and mechanical properties of bioactive dental filling materials based on chlorhexidine diacetate (CHX) or octinidine (di)hydrochloride (ODH) incorporated in a composite based on dimethacrylates or an ormocer. CHX or ODH were added to a nano-hybrid ormocer (O) and a nano-hybrid composite (C) with the amount of 2 wt% to achieve four matrix-drug combinations: O-CHX, O-ODH, C-CHX, and C-ODH. Drug extraction and release were measured using high-performance liquid chromatography with diode-array detection (HPLC-DAD), while drug distribution was assessed by using energy dispersive X-ray spectroscopy (EDX). Drug release in water at 37°C was observed over 87 d. To determine the material properties, the water absorption, water solubility, flexural strength and hardness were measured and compared to the reference materials. Persistent drug release over 87 d was observed for both ODH-based systems and both ormocer-systems, with the longest duration of activity seen for the O-ODH combination. Persistent drug release was achieved via the loosening of the polymer network indicated via decreasing polymerization enthalpies, enhanced water absorption, and water solubility. As a consequence, the flexural strengths of the materials were reduced. However, surface hardness was hardly reduced. ODH seems to be more adequate than CHX for the design of bioactive dental filling materials based on nano-hybrid ormocer and composites.

Antimicrobial agents in dental restorative materials: Effect on polymerization, short-term drug release and biological impact.

With the aim to design bioactive dental restorative material, the present study investigated the influence of the antimicrobial agents chlorhexidine diacetate (CHX) and octinidine (di)hydrochloride (ODH) when incorporated in two different materials. Selected parameters were polymerization enthalpy, short-term drug release, and the effect on Streptococcus mutans as well as human gingival fibroblasts. Samples were made by mixing a nano-hybrid ormocer (O) and a methacrylate-based nano-hybrid composite (C), each with a mass fraction of 2% CHX or ODH. Release profiles and concentrations of active agents from the resins were assessed, and the cell proliferation of human gingival fibroblasts as well as Streptococcus mutans cultured with the eluates were evaluated. The influence on polymerization was assessed by means of differential scanning calorimetry. Both drugs, especially ODH, showed a decreasing effect on polymerization enthalpies associated with a lowered crosslinking degree. At the same time ODH appeared to be released more persistently than CHX. Moreover, ODH was more efficient with regard to bacteria growth inhibition but also more cytotoxic in terms of reduction of cell viability. ODH is deemed more appropriate for application in a dental resin-based drug delivery system, because of the more persistent drug release than seen for CHX.

The effect of adjuvant oral irrigation on self-administered oral care in the management of peri-implant mucositis: A randomized controlled clinical trial.

OBJECTIVES: This single-blinded randomized clinical trial evaluated the effect of adjuvant oral irrigation in addition to self-administered oral care on prevalence and severity of peri-implant mucositis. MATERIAL & METHODS: After randomization, patients suffering from peri-implant mucositis were assigned to the following: Group 1 (control) received oral hygiene instruction following a standardized protocol, including a sub- and supramucosal mechanical debridement. Group 2 and 3 additionally were instructed to use an oral irrigator with either water or 0.06% CHX solution. One implant per patient was considered for examination. Clinical examinations included Probing Depth, Bleeding on Probing (BOP-positive sites), and Modified Plaque and Gingival Index. A surrogate variable (mucositis severity score) was applied measuring severity of disease. Statistical analysis included linear regression models and sensitivity analysis. RESULTS: Sixty periodontally healthy patients were examined for presence and severity of peri-implant mucositis. 70% of all patients reached complete resolution of disease after 12 weeks. The prevalence of peri-implant mucositis after 12 weeks was 50% in group 1, 35% in group 2, and 5% in group 3. Average BOP-positive sites were reduced in all groups after 12 weeks (mean change from baseline: group 1: -1.5; group 2: -1.8; group 3: -2.3). CONCLUSION: Within the limits of the study, adjuvant use of an oral irrigator with 0.06% CHX in addition to mechanical biofilm removal and oral hygiene instruction can reduce the presence and severity of peri-implant mucositis after 12 weeks.

Introducing a semi-coated model to investigate antibacterial effects of biocompatible polymers on titanium surfaces.

Peri-implant infections from bacterial biofilms on artificial surfaces are a common threat to all medical implants. They are a handicap for the patient and can lead to implant failure or even life-threatening complications. New implant surfaces have to be developed to reduce biofilm formation and to improve the long-term prognosis of medical implants. The aim of this study was (1) to develop a new method to test the antibacterial efficacy of implant surfaces by direct surface contact and (2) to elucidate whether an innovative antimicrobial copolymer coating of 4-vinyl-N-hexylpyridinium bromide and dimethyl(2-methacryloyloxyethyl) phosphonate (VP:DMMEP 30:70) on titanium is able to reduce the attachment of bacteria prevalent in peri-implant infections. With a new in vitro model with semi-coated titanium discs, we were able to show a dramatic reduction in the adhesion of various pathogenic bacteria (Streptococcus sanguinis, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis), completely independently of effects caused by soluble materials. In contrast, soft tissue cells (human gingival or dermis fibroblasts) were less affected by the same coating, despite a moderate reduction in initial adhesion of gingival fibroblasts. These data confirm the hypothesis that VP:DMMEP 30:70 is a promising antibacterial copolymer that may be of use in several clinical applications.

Automated Remodelling of Connectors in Fixed Partial Dentures.

In this study, an approach for automated parametric remodelling of the connector cross-sectional area in a CAD model of a given fixed partial denture (FPD) geometry was developed and then applied to a 4-unit FPD. The remodelling algorithm was implemented using Rhinoceros and the Grasshopper plugin. The generated CAD models were used to perform a finite element analysis with Ansys to analyse the stress distribution in an implant-supported 4-unit FPD for different connector designs. The results showed that the type of connector adjustment matters and that the resulting stress can be significantly different even for connectors with the same cross-sectional area. For tensile stresses, a reduction in the connector cross-sectional area from the gingival side showed the highest influence on each connector type. It can be concluded that the developed algorithm is suitable for automatic connector detection and adjustment.

Semi-automated generation of bone loss defects around dental implants and its application in finite element analysis.

This study aimed to develop an algorithm for modelling bone loss defects in a given mandibular geometry, with a user-defined depth, width, place, and defect type. The algorithm was implemented using Grasshopper and models with different bone loss types and depths around a dental implant were built. The models were used in a finite element analysis (FEA) to predict the stresses in peri-implant bone. The FEA showed that the stresses in peri-implant bone depend primarily on the depth of bone loss, whereas the type of bone loss showed no major influence.

The effect of surface treatments on the adhesive bond in all-ceramic dental crowns using four-point bending and dynamic loading tests.

The aim of this study was to determine the effect of sandblasting, grinding and plasma treatment on the adhesive bond strength between framework ceramic (Y-TZP) and veneering ceramic (feldspar ceramic). Therefore, four-point bending specimens (n = 180) were cut from densely sintered 3Y-TZP blanks. Subsequently, 80 of these samples received surface treatment by sandblasting and 80 samples by grinding. A reference group (20 samples) was not processed. Half of the specimens that received a surface treatment were additionally exposed to an oxygen plasma treatment. After processing, all specimens were manually veneered with feldspar ceramic and examined with a four-point bending test to evaluate the strain energy release rate G. The surface treatment parameters that achieved the highest and lowest G were transferred to real geometries of a posterior crown (n = 45). The crowns' ceramic framework was sandblasted and veneered by hand. The all-ceramic crowns were tested in a dynamic loading test and Wöhler curves were evaluated. Four-point bending samples blasted at an angle of 90° at 6 bar and a working distance of 1.5 cm without plasma treatment achieved the highest energy release rate. Samples blasted at an angle of 90° at 2 bar and a working distance of 1 cm with plasma treatment achieved the lowest energy release rate. Overall, plasma treatment did not improve bond strength. In the dynamic loading test, the group blasted with 2 bar showed the best results.

Fracture Resistance of Repaired 5Y-PSZ Zirconia Crowns after Endodontic Access.

This study analyzed the fracture load before and after a chewing simulation of zirconia crowns that were trepanned and repaired using composite resin. Overall, 3 groups with 15 5Y-PSZ crowns in each group were tested. For group A, the fracture load of the unmodified crowns was evaluated. For group B, the crowns were trepanned and repaired using composite resin, also followed by a fracture test. For group C, crowns were prepared like in group B but received thermomechanical cycling before the final fracture tests. Furthermore, scanning electron microscopy (SEM) and X-ray microscopy (XRM) analysis were performed for group C. The mean fracture loads and standard deviation were 2260 N ± 410 N (group A), 1720 N ± 380 N (group B), and 1540 N ± 280 N (group C). Tukey-Kramer multiple comparisons showed a significant difference between groups A and B (p < 0.01) and groups A and C (p < 0.01). After ageing, surface fissures were detected via SEM, but no cracks that reached from the occlusal to the inner side of the crown were detected via XRM. Within the limitations of this study, it can be stated that trepanned and composite-repaired 5Y-PSZ crowns show lower fracture loads than 5Y-PSZ crowns without trepanation.

Influence of VAC Therapy on Perfusion and Edema of Gracilis Flaps: Prospective Case-control Study.

The gracilis muscle flap is a popular choice in reconstructive surgery to repair soft tissue defects or for functional restoration. Little is known on the influence of postoperative application of VAC (vacuum-assisted closure; Kinetic Concepts Inc., San Antonio, Tex.) therapy on perfusion and postoperative flap edema of free gracilis muscle flaps. Methods: In total, 26 patients with soft tissue defects of lower extremity underwent gracilis muscle flap reconstruction. The study group (VAC, n = 13) was supplied with postoperative negative pressure therapy as a dressing; the control group (NVAC, n = 13) was supplied with conventional fat gauze dressing. Postoperative measurements of micro- and macroperfusion were performed intraoperatively, on postoperative day (POD) 3 and POD 5. Flap edema measurement was performed intraoperatively, on POD 5 and 2 weeks after operation. Results: The VAC group showed significantly better macroflow during intraoperative VAC treatment, as well on POD 3 and POD 5. Venous outflow was also better with lower hemoglobin levels. Microflow was better in the NVAC group with higher measured oxygen levels. All gracilis muscle flaps of the VAC group showed significantly less flap edema compared with the control group. Conclusions: VAC application on free gracilis muscle flaps leads to significantly less postoperative flap edema, improved arterial macroflow, and improved venous outflow. VAC therapy can be used without any danger for patient's safety, as flap survival is not endangered, and presents an easy to handle and pleasant dressing regimen for nursing staff and patients.

Effect of titanium implants along with silver ions and tetracycline on type I interferon-beta expression during implant-related infections in co-culture and mouse model.

Type I interferon-beta (IFN-ß) is a crucial component of innate and adaptive immune systems inside the host. The formation of bacterial biofilms on medical implants can lead to inflammatory diseases and implant failure. Biofilms elicit IFN-ß production inside the host that, in turn, restrict bacterial growth. Biofilms pose strong antibiotic resistance, whereas surface modification of medical implants with antibacterial agents may demonstrate strong antimicrobial effects. Most of the previous investigations were focused on determining the antibacterial activities of implant surfaces modified with antibacterial agents. The present study, for the first time, measured antibacterial activities and IFN-ß expression of titanium surfaces along with silver or tetracycline inside co-culture and mouse models. A periodontal pathogen: Aggregatibacter actinomycetemcomitans reported to induce strong inflammation, was used for infection. Silver and tetracycline were added to the titanium surface using the heat evaporation method. Macrophages showed reduced compatibility on titanium surfaces with silver, and IFN-ß expression inside cultured cells significantly decreased. Macrophages showed compatibility on implant surfaces with tetracycline, but IFN-ß production significantly decreased inside seeded cells. The decrease in IFN-ß production inside macrophages cultured on implant surfaces with silver and tetracycline was not related to the downregulation of Ifn-ß gene. Bacterial infection significantly upregulated mRNA expression levels of Isg15, Mx1, Mx2, Irf-3, Irf-7, Tlr-2, Tnf-α, Cxcl-1, and Il-6 genes. Notably, mRNA expression levels of Mx1, Irf7, Tlr2, Tnf-α, Cxcl1, and Il-6 genes inside macrophages significantly downregulated on implant surfaces with silver or tetracycline. Titanium with tetracycline showed higher antibacterial activities than silver. The in vivo evaluation of IFN-ß expression around implants was measured inside transgenic mice constitutive for IFN-ß expression. Of note, the non-invasive in vivo imaging revealed a significant decrease in IFN-ß expression around subcutaneous implants with silver compared to titanium and titanium with tetracycline in sterile or infected situations. The histology of peri-implant tissue interfaces around infected implants with silver showed a thick interface with a significantly higher accumulation of inflammatory cells. Titanium implants with silver and tetracycline remained antibacterial in mice. Findings from this study unequivocally indicate that implant surfaces with silver decrease IFN-ß expression, a crucial component of host immunity.

Abrasion Behavior of Different Charcoal Toothpastes on Human Dentin When Using Electric Toothbrushes.

The aim of this study was to investigate abrasion on human dentin after brushing with activated charcoal toothpastes. A self-designed brushing machine was used to brush five groups (Group A: Water, Group B: Sensodyne Pro Schmelz, Group C: Splat Blackwood, Group D: Curaprox Black is White, and Group E: Prokudent Black Brilliant) with electrically powered toothbrushes for 4 h. The abrasive dentin wear was calculated using profilometry data. Furthermore, thermogravimetric analyses and scanning electron microscopy were used to analyze the composition of the toothpastes. Mean dentin loss by brushing were (71 ± 28) µm (Splat Blackwood), (44 ± 16) µm (Curaprox Black is White), (38 ± 13) µm (Prokudent Black Brilliant), (28 ± 14) µm (Sensodyne Pro Schmelz), and (28 ± 13) µm (Water). Groups A/B/D/E and group C each lie in one subset, which is statistically different from the other subset according to a post hoc Tukey test (p = 0.05). Within the limitations, it can be concluded that the content of activated charcoal in charcoal toothpastes had little influence on the observed abrasive behavior, although one of the charcoal toothpastes showed the highest abrasion on dentin.

Bacterial-Specific Induction of Inflammatory Cytokines Significantly Decreases upon Dual Species Infections of Implant Materials with Periodontal Pathogens in a Mouse Model.

Cytokine profiles are often perturbed after infections of medical implants. With a non-invasive in vivo imaging system, we report in a mouse model that interferon expression after infection of subcutaneous implants with Streptococcus oralis, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, and Treponema denticola (alone or as a combination) was species-specific, persisted longer in the presence of implants, and notably decreased upon dual species infections. This type I interferon expression disappeared within two weeks; however, histology of implant-tissue interface indicated high recruitment of immune cells even after three weeks. This was suggestive that biomaterial-associated infections could have prolonged effects, including the systemic stimulation of inflammatory cytokines. The present study investigated the systemic impact of this chronic peri-implant inflammation on the systemic expression of inflammatory cytokines (23) using a multiplex assay. Initially, the cytokine measurement in murine fibroblasts exposed to periodontal pathogens remained limited to the expression of five cytokines, namely, IL-6, G-CSF, CXCL-1/KC, MCP-1 (MCAF), and IL-12 (p40). The systemic determination of cytokines in mice increased to 19 cytokines (IL-1α, IL-2, IL-3, IL-5, IL-6, IL-9, IL-12 (p40), IL-12 (p70), IL-13, IL-17A, CCL-11/Eotaxin, G-CSF, IFN-γ, CXCL1/KC, MCP-1 (MCAF), MIP-1α/CCL3, MIP-1ß/CCL4, CCL5/RANTES, and TNF-α). Systemic induction of cytokines was species-specific in the mouse model. The cytokine induction from infected implants differed significantly from sole tissue infections and sterile implants. Notably, systemic cytokine induction decreased after infections with dual species compared to single species infections. These findings describe the systemic effect of chronic peri-implant inflammation on the systemic induction of inflammatory cytokines, and this effect was strongly correlated to the type and composition of initial infection. Systemic modulations in cytokine expression upon dual species infections exhibit an exciting pattern that might explain the complications associated with biomaterial-related infection in patients. Moreover, these findings validate the requirement of multispecies infections for pre-clinical studies involving animal models.

Fracture stability of anterior zirconia crowns with different core designs and veneered using the layering or the press-over technique.

In the current in vitro study, the fracture stability of anterior crowns with zirconia cores of different designs was investigated after applying different veneering techniques. Four groups of zirconia cores (n = 10 in each group) were produced using a computer-aided design/computer-aided manufacturing (CAD/CAM) process. Cores with a standard cervical design were veneered using the layering technique (CCL) or the press-over technique (CCP). Further cores were designed with a porcelain shoulder, where the cervical margin of the zirconia core was reduced by 1 mm. These cores were also veneered using the layering technique (PSL) or the press-over technique (PSP). All crowns were cemented onto metal teeth and loaded until fracture in a universal testing machine. Chipping or fracture of the core was found to occur for CCL at 919±265 N (mean ±SD), for CCP at 798±226 N, for PSL at 739±184 N, and for PSP at 734±209 N. anova did not show significant differences between the four groups. For CCL and CCP, fracture lines ran in a mesio-distal orientation. For PSL and PSP, fracture lines ran into the porcelain shoulder. In summary, the use of a porcelain shoulder can be recommended with zirconia crowns in combination with either the layering or the press-over veneering technique.

Abrasion Behaviour of Different Charcoal Toothpastes When Using Electric Toothbrushes.

OBJECTIVES: The purpose of this in vitro study was to compare the abrasion behaviour of different charcoal toothpastes when brushing with electric toothbrushes on human enamel. MATERIALS AND METHODS: A self-designed brushing machine was built using six commercially available electric toothbrushes in abrasion chambers. Each chamber was constantly supplied with a toothpaste-water mix. Pieces of human enamel, which were embedded in PMMA, were brushed for 4 h. Before and after brushing, profilometer measurements were performed in order to determine the substance loss due to brushing. RESULTS: The following calculated mean removal values (mean ± SD) were found: (4.6 ± 0.6) µm (Group C: Splat Blackwood), (3.2 ± 0.9) µm (Group D: Curaprox Black is White), (2.3 ± 0.7) µm (Group B: Sensodyne Pro Schmelz), (1.7 ± 0.6) µm (Group A: Water), (1.4 ± 0.6) µm (Group E: Prokudent Black Brilliant). A post hoc Tukey HSD test (p = 0.05) showed that the results for Group A/B/E, Group B/D and Group C each lie within subsets that differ statistically significantly from the other subsets. CONCLUSIONS: Within the limitations of this in vitro study, it can be stated that some charcoal toothpastes lead to significantly higher abrasion on human enamel, when brushing with electric brushes. CLINICAL RELEVANCE: As low-abrasion toothpaste is generally advisable, and some charcoal toothpastes should be viewed critically with regard to their abrasive properties.

Non-Invasive Luciferase Imaging of Type I Interferon Induction in a Transgenic Mouse Model of Biomaterial Associated Bacterial Infections: Microbial Specificity and Inter-Bacterial Species Interactions.

The performance of biomaterials is often compromised by bacterial infections and subsequent inflammation. So far, the conventional analysis of inflammatory processes in vivo involves time-consuming histology and biochemical assays. The present study employed a mouse model where interferon beta (IFN-ß) is monitored as a marker for non-invasive rapid detection of inflammation in implant-related infections. The mouse model comprises subcutaneous implantation of morphologically modified titanium, followed by experimental infections with four taxonomically diverse oral bacteria: Streptococcus oralis, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Treponema denticola (as mono culture or selected mixed-culture). IFN-ß expression increased upon infections depending on the type of pathogen and was prolonged by the presence of the implant. IFN-ß expression kinetics reduced with two mixed species infections when compared with the single species. Histological and confocal microscopy confirmed pathogen-specific infiltration of inflammatory cells at the implant-tissue interface. This was observed mainly in the vicinity of infected implants and was, in contrast to interferon expression, higher in infections with dual species. In summary, this non-invasive mouse model can be used to quantify longitudinally host inflammation in real time and suggests that the polymicrobial character of infection, highly relevant to clinical situations, has complex effects on host immunity.

The effect of different occlusal contact situations on peri-implant bone stress - A contact finite element analysis of indirect axial loading.

Implant restoration is one of the basic treatments in dentistry today, yet implant loss from occlusal overload is still a problem. Complex biomechanical problems such as occlusal overload are often analyzed by means of the finite element method. This numerical method makes it possible to analyze in detail the influence that different loading situations have upon implants and tissues, which is a key element in optimizing these dental procedures. This study was designed to investigate the stress distribution in peri-implant bone of a single-tooth implant crown using the finite element method. The load was applied indirectly via an occluding tooth through a three and five contact setup into the implant crown. The friction coefficient values between the crown and antagonist were varied between 0.1 and 1.0. Additionally, three crowns with cusp inclinations of 20°, 30° and 40° were modeled. Non-linear contact computations indicated that an increase in friction changed the direction and magnitude of contact forces, which also led to reduced stresses in the bone. Furthermore, the stress magnitudes were higher when cusps of a greater inclination were used. The intensity of stress alterations was strongly dependent on the distribution and number of contacts, and the contact force vector. In maximum intercuspation, a resulting axial load due to well-distributed contacts prevented high stresses in bone even with high cusp inclinations and low friction. Therefore for long-term clinical success, particular attention should be paid to occlusal adjustment so as to prevent oblique loading onto dental implant restorations.

Survival rate of modern all-ceramic FPDs during an observation period from 2011 to 2016.

PURPOSE: In literature, many studies compare survival rates of different types of FPDs. Most of them compared restorations, which originated from one university, but from different clinicians. Data about restoration survival rates by only one experienced dentist are very rare. The aim of this study was to evaluate the survival rate of allceramic FPDs without the blurring effects of different clinicians. MATERIALS AND METHODS: 153 veneeredzirconia FPDs were observed for follow-up. 22 patients received 131 single crowns and 22 bridges. Because of the different bridge lengths, one unit was defined as a restored or replaced tooth. In total, 201 units were included. Only the restorations performed by the same clinician and produced in the same dental laboratory from 2011 to 2016 were included. Considered factors were defined as "type of unit", "type of abutment", "intraoral region", and "vitality". Modified UHPHS criteria were used for evaluation. Statistical analysis was performed using cox-regression. RESULTS: 189 units (94.0%) showed no kind of failure. 5 chippings (2.4%) could be corrected by intraoral polishing. 4 units (1.9%) exhibited spontaneous decementation. These polishable and recementable restorations are still in clinical use. Chippings or decementations, which lead to total failure, did not occur. One unit was completely fractured (0.5 %). Biological failures (caries, periodontitis or periimplantitis) did not occur. The statistical analysis of the factors did not reveal any significant differences. CONCLUSION: Modern all-ceramic FPDs seem to be an appropriate therapy not only for single restorations but for complex occlusal rehabilitations.

Influence of nonthermal argon plasma on the shear bond strength between zirconia and different adhesives and luting composites after artificial aging.

PURPOSE: Plasma activation of hydrophobic zirconia surfaces might be suitable to improve the bond strength of luting materials. The aim of this study was to analyze the influence of nonthermal argon-plasma on the shear bond strength (SBS) between zirconia and different combinations of 10-MDP adhesive systems and luting composites after artificial aging. MATERIALS AND METHODS: Two hundred forty Y-TZP specimens were ground automatically with 165 µm grit and water cooling. Half of the specimens received surface activation with nonthermal argon-plasma. The specimens were evenly distributed into three groups according to the adhesive systems ([Futurabond U, Futurabond M, Futurabond M + DCA], VOCO GmbH, Germany, Cuxhaven) and into further two subgroups according to the luting materials ([Bifix SE, Bifix QM], VOCO GmbH). Each specimen underwent artificial aging by thermocycling and water storage. SBS was measured in a universal testing machine. Statistical analysis was performed using ANOVA and Scheffè procedure with the level of significance set to 0.05. RESULTS: Surface activation with nonthermal plasma did not improve the bond strength between zirconia and the tested combinations of adhesive systems and luting materials. The plasma-activation trended to reveal higher bond strength if the self-etch luting material (Bifix SE) was used, irrespective of the adhesive system. CONCLUSION: Plasma-activation seems to be suitable to improve bond strength between zirconia and self-etch resin materials. However, further research is necessary to identify the influence of varying plasma-parameters.

Polish of interface areas between zirconia, silicate-ceramic, and composite with diamond-containing systems.

PURPOSE: Fractures, occlusal adjustments, or marginal corrections after removing excess composite cements result in rough surfaces of all-ceramic FPDs. These have to be polished to prevent damage of the surrounding tissues. The aim of this study was to evaluate the roughness of zirconia, silicate-ceramic, and composite after polish with different systems for intraoral use. MATERIALS AND METHODS: Each set of 50 plates was made of zirconia, silicate-ceramic, and composite. All plates were ground automatically and were divided into 15 groups according to the treatment. Groups Zgrit, Sgrit, and Cgrit received no further treatment. Groups Zlab and Slab received glaze-baking, and group Clab was polished with a polishing device. In the experimental groups Zv, Sv, Cv, Zk, Sk, Ck, Zb, Sb, and Cb, the specimens were polished with ceramic-polishing systems "v", "k", and "b" for intraoral use. Roughness was measured using profilometry. Statistical analysis was performed with ANOVA and Scheffé-procedure with the level of significance set at P=.05. RESULTS: All systems reduced the roughness of zirconia, but the differences from the controls Zgrit and Zlab were not statistically significant (P>.907). Roughness of silicate ceramic was reduced only in group Sv, but it did not differ significantly from both controls (P>.580). Groups Cv, Ck, and Cb had a significantly rougher surface than that of group Clab (P<.003). CONCLUSION: Ceramic materials can be polished with the tested systems. Polishing of interface areas between ceramic and composite material should be performed with polishing systems for zirconia first, followed by systems for veneering materials and for composite materials.