Background: The adhesive connection between titanium base and zirconia coping of two-part abutments may be responsible for the failure rate. A high mechanical stability between both components is essential for the long-term success.

To investigate whether there are differences in patients' denture satisfaction when an implant placed in the midline of the edentulous mandible is loaded either immediately or three months later, after second-stage surgery. One hundred and fifty-eight edentulous patients received a single implant in the midline of the mandible. After randomisation, it was loaded either immediately after implant placement (N = 81, group A) or three months later, after a submerged healing phase and a second-stage surgery (N = 77, group B). Patients' denture satisfaction aspects were assessed, using visual analogue scales (VAS), before treatment, one month after implant placement during the submerged healing phase (only group B) and one and four months after implant loading. The statistical analysis was performed using the Wilcoxon signed-rank and rank-sum tests. One month after loading, a significant improvement in comfort, function and stability of the mandibular denture could be observed in both groups (P ≤ 0·05). A slight but not significant improvement was found between one and four months after loading. Patients with second-stage surgery and delayed loading rated the stability and fit of the mandibular denture as significantly better than patients who had immediate loading. A single implant in the edentulous mandible significantly increased patients' denture satisfaction. After four months, stability and fit of the mandibular denture were considered better when a delayed loading protocol had been followed. A single mandibular implant in the edentulous mandible significantly increases patients' denture satisfaction, regardless of the loading protocol.

Objectives The aim of this study was to evaluate volume, vitality and diversity of biofilms on the abutment materials zirconia and titanium as a function of time using an in vivo model for the biofilm formation. Materials and methods The development of biofilms on zirconia and titanium grade 4 test specimens in the human oral cavity over time was analysed. After pretreatment, a total of 96 titanium and 96 zirconia discs were fixed on 12 composite splints, which were worn by 12 volunteers. After 6 hr, 24 hr, 3 days and 5 days, biofilms on 48 specimens of each material were analysed with confocal laser scanning microscopy (CLSM). The microbiota composition on the other 48 test specimens was examined using full‐length 16S sequence analysis. Statistical analysis was performed by SPSS and R, and level of significance was set at 0.05. Results Confocal laser scanning microscopy analysis of the biofilms revealed significant changes in volume over time on zirconia and titanium. The material did not significantly influence the volume or live/dead ratio at the individual time points. The composition of the microbiome was influenced by the age of the biofilm, but not by the material of the test specimen. The most frequently found bacteria were Streptococcus spp., followed by Neisseria spp., Rothia spp., Haemophilus spp., Gemella spp. and Abiotrophia spp. Conclusions On both materials, the quantity and diversity of the microbiome increased over time. Apart from a slight difference in Veillonella abundance at one time point, there were no significant differences between zirconia and titanium.

Objectives Two‐part abutments consist of titanium base and ceramic coping. Their long‐term success is largely determined by the mechanical stability. The aim of the present study was to investigate the retention forces of two‐part implant abutments. The study included zirconia and lithium disilicate ceramics copings, with different surface treatments and resin‐based luting agents. Material and Methods The analysis of retention forces was based on a total of 70 test specimens. Seven surface modifications and three resin‐based luting agents were employed for the bonding of components in the seven groups (n = 70). All surfaces of titanium bases—except for a control—were pretreated with aluminum oxide blasting, either alone or in combination with surface activating primers. Surfaces of ceramic copings were also treated mechanically by sandblasting, either alone or with acid etching or different primers. All specimens underwent thermal aging (104 cycles, 5°C/55°C). The retention forces between the two parts were measured with a pull‐off test. The results were analyzed by two‐way ANOVA statistics. Fracture patterns were evaluated by light and scanning electron microscopy. Results No mechanical pretreatment of the titanium (group 2) base resulted in the lowest retention. The combination with Monobond plus leads to the highest pull‐off forces for both ceramic materials. Conclusions Surface modifications and resin‐based agents influence the retention of components of two‐part abutments. Lithium disilicate ceramic copings reached comparable results of retention to the typically used zirconia copings.

The use of zirconia-reinforced lithium silicate ceramic for molar nonprep table tops should be uncomplicated according to the high load-at-fracture values. Mechanical stability of either ceramic is not compromised by aging.

Abstract:Background: The aim of the study was to evaluate the antibacterial effect of a drug releasing poly (3-hydroxybutyrate) (P(3HB)) implant coating in comparison to pure titanium on Aggregatibacter actinomycetemcomitans as a model periodontopathogen to prevent biofilm formation on implant surfaces. Methods: Titanium discs were coated with P(3HB) containing 5% (w) and 10% (w) of metronidazole, either with and without a P(3HB) topcoat. The biofilm formation was evaluated after 1, 4 and 9 days in a dynamic flow chamber system. Microbial adherence was quantified by determination of bacterial surface coverage. Results: The evaluated formulations of P(3HB)/metronidazole showed an antibacterial effect especially in the first 24 h. Prolonged incubation for 9 days showed reduced bacterial adhesion only on polymer coatings loaded with 10% (w) of metronidazole both with and without topcoat. Conclusions:The evaluated coating formulations can provide protection from an Aggregatibacter actinomycetemcomitans in vitro biofilm formation for the time period which was evaluated.

PURPOSE. The purpose of this in vitro study was to evaluate the fitting accuracy of single crowns made from a novel presintered Co-Cr alloy prepared with a computer-aided design and computer-aided manufacturing (CAD/ CAM) technique, as compared with crowns manufactured by other digital and the conventional casting technique. Additionally, the influence of oxide layer on the fitting accuracy of specimens was tested. MATERIALS AND METHODS. A total of 40 test specimens made from Co-Cr alloy were investigated according to the fitting accuracy using a replica technique. Four different methods processing different materials were used for the manufacture of the crown copings (milling of presintered (Ceramill Sintron-group_cer_sin) or rigid alloy (Tizian NEM-group_ti_nem), selective laser melting (Ceramill NPL-group_cer_npl), and casting (Girobond NB-group_gir_ nb)). The specimens were adapted to a resin model and the outer surfaces were airborne-particle abraded with aluminum oxide. After the veneering process, the fitting accuracy (absolute marginal discrepancy and internal gap) was evaluated by the replica technique in 2 steps, before removing the oxide layer from the intaglio surface of the crowns, and after removing the layer with aluminum oxide airborne-particle abrasion. Statistical analysis was performed by multifactorial analysis of variance (ANOVA) (α=.05). RESULTS. Mean absolute marginal discrepancy ranged between 20 μm (group_cer_npl for specimens of Ceramill NPL) and 43 μm (group_cer_sin for crowns of Ceramill Sintron) with the oxide layer and between 19 μm and 28 μm without the oxide layer. The internal gap varied between 33 μm (group_ti_nem for test samples of Tizian NEM) and 75 μm (group_gir_nb for the base material Girobond NB) with the oxide layer and between 30 μm and 76 μm without the oxide layer. The absolute marginal discrepancy and the internal gap were significantly influenced by the fabrication method used (P<.05). CONCLUSION. Different manufacturing techniques had a significant influence on the fitting accuracy of single crowns made from Co-Cr alloys. However, all tested crowns showed a clinically acceptable absolute marginal discrepancy and internal gap with and without oxide layer and could be recommended under clinical considerations. Especially, the new system Ceramill Sintron showed acceptable values of fitting accuracy so it can be suggested in routine clinical work.

INTRODUCTION Oral diseases are the most prevalent chronic infections in the world (1); in most cases tooth decay and periodontitis are reasons for that (2, 3). Most of the oral disorders are bacterial biofilm driven. Biofilm formation is a natural occurring process in the oral cavity and so far more than 700 different bacteria have been shown to cooperate in oral microbial communities (4). In sessile microbial communities, the cells are embedded in a matrix of self-secreted polymeric substances, such as DNA, proteins or polysaccharides which forms a diffusion barrier against antimicrobial substances, predation and host immune response (5), and adapt metabolic activity to the biofilm lifecycle. As a consequence, antibiotic resistance may increase by several hundred folds and renders drug treatment often ineffective (6, 7). These days, the use of copper as an antibacterial compound has gained increasing attention (8-13), e.g. copper and copper alloys have been registered as the first solid antimicrobial material by U.S. Environmental Protection Agency in 2010 (8). Several mechanisms of antibacterial actions of copper ions have been proposed: a) formation of hydroxyl radicals (14), b) oxidative crosslinking of thiol residues in proteins (8) and c) competition between copper-and other metal ions for protein binding sites (15, 16). The use of calcium hydroxide as a disinfectant agent in dentistry was introduced in the 1920 by B.W. Hermann (17). Since then, it has become one of the major antiseptic preparations in endodon-Objective: This study aimed to assess the efficacy of Cupral®, a Ca(OH) 2 and Cu 2+ based materials used in endodontics, against biofilms of the oral species Streptococcus oralis, Streptococcus gordonii and Aggregatibacter actinomycetemcomitans at different maturation stages. Methods: Biofilms of the bacterial target species were grown in brain heart infusion (BHI) medium for 1 and 5 days on titanium disks (titanium, grade 4) to collect microbial communities at different stages of biofilm maturation. Biofilms were subjected to different Cupral® concentrations (4-, 15-and 50-fold dilution) to assess the antimicrobial-and biofilm dissolving effect. 0.2% chlorhexidine gluconate (CHX) solution was used as a positive control. Biovolume and antibacterial efficacy were analyzed by live/dead staining in combination with confocal laser scanning microscopy (CLSM) to quantify biofilm detachment and antibacterial efficacy. Results: All tested Cupral® concentration showed a strong antibacterial effect on tested bacterial species at all biofilm maturation stages. Efficacy of biofilms detachment was concentration dependent, i.e. higher Cupral® concentrations generally led to increased biofilm detachment. The antibacterial efficacy of tested Cupral® concentration was at least equal to CHX treatment (P=0.03). Conclusion: Cupral® shows a strong anti-biofilm efficacy and may be applied for oral biofilm treatment and control in dental disciplines other than endodontics.