Roughness and SEM Analysis of Manual and Ultrasonic Instrumentation over Different Crown Materials for Dental Implants Restorations.

The use of new prosthetic materials makes it necessary to establish adequate hygienic protocols. It was decided to make prosthetic crowns from four different materials: composite, lithium disilicate, metal ceramic, and zirconium, and to evaluate the effects on the surfaces of four different instruments through SEM and roughness analysis: manual steel curette, manual titanium curette, ultrasonic steel insert, and ultrasonic peek insert. Forty crowns were made, ten of each type of material. For each material, five crowns were manually instrumented with steel inserts (curette 11-12, PDT, Missoula, MT, USA) and titanium (Wingrove 3-4, PDT, Missoula, MT, USA) on the lingual and buccal surfaces, respectively, and the other five crowns were instrumented with an ultrasonic peek insert (ICS-IC1, Mectron, Carasco, Italy) on the buccal surface and steel (PS, EMS, Nyon, Switzerland) on the lingual surface. At this point, surface roughness analysis was carried out. The data were analyzed with a Kolmogorov-Smirnov test. Therefore, it was decided to conduct two analyses with a Kruskal-Wallis test and Bonferroni post hoc test. Then, the instrumented crowns were analyzed by SEM. The analysis of the data shows that the highest average roughness was within the composite group, while the best material appeared to be disilicate. Significant differences existed between the groups, between the materials, and between the different instruments (p-value < 0.05). In the qualitative analysis carried out by SEM, the classic steel insert eliminated the residues of golden finishing. The peek insert created alterations on all tested surfaces. The steel curette did not create particular problems, with the exception of zirconium, where it was possible to observe some scratch lines. Instrumentation with the titanium curette created deeper incisions than the steel curette in the composite and disilicate. The best results came from the ultrasonic steel insert, while the best material appeared to be disilicate.

A Response Surface Methodology Approach to Improve Adhesive Bonding of Pulsed Laser Treated CFRP Composites.

In this work, a response surface-designed experiment approach was used to determine the optimal settings of laser treatment as a method of surface preparation for CFRP prior to bonding. A nanosecond pulsed Ytterbium-doped-fiber laser source was used in combination with a scanning system. A Face-centered Central Composite Design was used to model the tensile shear strength (TSS) of adhesive bonded joints and investigate the effects of varying three parameters, namely, power, pitch, and lateral overlap. The analysis was carried out considering different focal distances. For each set of joints, shear strength values were modeled using Response Surface Methodology (RSM) to identify the set-up parameters that gave the best performance, determining any equivalent conditions from a statistical point of view. The regression models also allow the prediction of the behavior of the joints for not experimentally tested parameter settings, within the operating domain of investigation. This aspect is particularly important in consideration of the process optimization of the manufacturing cycle since it allows the maximization of joint efficiency by limiting the energy consumption for treatment.

Functionalization of Neutral Polypropylene by Using Low Pressure Plasma Treatment: Effects on Surface Characteristics and Adhesion Properties.

Polyolefins are considered among the most difficult polymeric materials to treat because they have poor adhesive properties and high chemical barrier responses. In this paper, an in-depth study is reported for the low pressure plasma (LPP) treatment of neutral polypropylene to improve adhesion properties. Changes in wettability, chemical species, surface morphology and roughness of the polypropylene surfaces were evaluated by water contact angle measurement, X-ray photoelectron spectroscopy and, furthermore, atomic force microscopy (AFM). Finally, the bonded joints were subjected to tensile tests, in order to evaluate the practical effect of changes in adhesion properties. The results indicate that plasma is an effective treatment for the surface preparation of polypropylene for the creation of bonded joints: contact angles decreased significantly depending on the plasma-parameter setup, surface morphology was also found to vary with plasma power, exposure time and working gas.

Influence of Adhesive in FSW: Investigation on Fatigue Behavior of Welded, Weld-Bonded, and Adhesive-Bonded Joints in Aluminum AA 6082 T6.

Friction stir welding (FSW) is a solid-state technique, which has assumed an increasingly important role in automotive, naval, and aeronautical industry over the years. Nowadays, thanks to its several benefits, FSW is used to weld any type of metallic, polymeric, or composite material. In recent decades, adhesive bonding has also enhanced relevance due to a request for much lighter structures to increase performance without increasing fuel consumption. From a mechanical perspective, welding has a high tensile strength despite a low fatigue resistance through the lack of joint elasticity. Therefore, the aim of this study is to investigate and compare static and dynamic behavior of welded, weld-bonded, and adhesive-bonded joints. After choosing the most suitable adhesive, surface preparation, consisting of sandblasting, was carried out. First of all, on the basis of previous experience in FSW, the process parameters of hybrid welding were determined. Both quasi-static and dynamic behavior of welded, adhesive-bonded, and weld-bonded joints, made in overlapped configuration, were then compared. Experimental tests showed that the adhesive limits the negative effect, due to the presence of the structural notch of FSW overlapped joints.

Evaluation of a New Ultrasonic Insert for Prosthodontic Preparation.

PURPOSE: This paper describes a new ultrasonic instrument (tipholder DB1 with crown prep tip inserts) designed to optimize prosthodontic margin repositioning and finishing. MATERIALS AND METHODS: The insert movement was assessed, and it was demonstrated that tipholder DB1 provides its inserts with an elliptical-like movement, making the entire insert surface able to cut. Then, 20 extracted teeth were prepared using tipholder DB1, sonic instruments, and traditional drills. Dental surface roughness produced using each of the three tools was measured using a roughness tester. Results were compared using univariate analysis of variance and Bonferroni post hoc test. RESULTS: The roughness produced using tipholder DB1 with crown prep insert presented no statistically significant differences compared to the roughness produced using sonic instruments and traditional drills. CONCLUSION: Tipholder DB1 with crown prep inserts is a promising treatment for margin repositioning and finishing.