The aim of this in vitro study was to evaluate the effect of air polishing on the implant abutment surface using different abrasive powders: sodium bicarbonate and amino acid glycine. Fifteen grade III machined surface titanium disks with 8-mm diameter and 2-mm thickness were divided in 3 groups of 5 samples each and subjected to air polishing for 20 seconds with an Ultrajet Flex air-abrasive device and a distinct prophylaxis protocol: air and water (G1); air, water, and sodium bicarbonate (G2); and air, water; and amino acid glycine (G3). After the air polishing, the average roughness (Ra) of the samples was measured using an optical profilometer, and the obtained data were statistically analyzed. We found that G1 and G3 had similar Ra, while Ra values for G2 were significantly higher. This study demonstrated that air-polishing powders containing glycine had less of an effect on the roughness of the surface of titanium disks compared with sodium bicarbonate powders. Future in vivo studies will be conducted to investigate the clinical relevance of the present results.
OBJECTIVES: This study investigated the effect of porcelain firing on the misfit of implantsupported frameworks and analyzed the influence of preheat treatment on the dimensional alterations. MATERIALS AND METHODS: Four external-hex cylindrical implants were placed in polyurethane block. Ten frameworks of screw-retained implant-supported prostheses were cast in Pd-Ag using 2 procedures: (1) control group (CG, n = 5): cast in segments and laser welded; and test group (TG, n = 5): cast in segments, preheated, and laser welded. All samples were subjected to firing to simulate porcelain veneering firing. Strain gauges were bonded around the implants, and microstrain values ( = 10 ) were recorded after welding (M1), oxidation cycle (M2), and glaze firing (M3). Data were statistically analyzed (2-way analysis of variance, Bonferroni, = 0.05). RESULTS: The microstrain value in the CG at M3 (475.2 ) was significantly different from the values observed at M1 (355.6 ) and M2 (413.9 ) ABSTRACT (189 WORDS)Objectives: This study investigated the effect of porcelain firing on the misfit of implant-supported
STATEMENT OF PROBLEM An imprecise fit between frameworks and supporting dental implants in loaded protocols increases the strain transferred to the periimplant bone, which may impair healing or generate microgaps. PURPOSE The purpose of this study was to investigate the microstrain between premachined 1-piece screw-retained frameworks (group STF) and screw-retained frameworks fabricated by cementing titanium cylinders to the prefabricated framework (group CTF). This procedure was developed to correct the misfit between frameworks and loaded implants. MATERIAL AND METH-ODS Four internal hexagon cylindrical implants were placed 10 mm apart in a polyurethane block by using the surgical guides of the corresponding implant system. Previously fabricated titanium frameworks (n=10) were divided into 2 groups. In group STF, prefabricated machined frameworks were used (n=5), and, in group CTF, the frameworks were fabricated by using a passive fit procedure, which was developed to correct the misfit between the cast titanium frameworks and supporting dental implants (n=5). Both groups were screw-retained under torque control (10 Ncm). Six strain gauges were placed on the upper surface of the polyurethane block, and 3 strain measurements were recorded for each framework. Data were analyzed with the Student t test (=.05). RESULTS The mean microstrain values between the framework and the implants were significantly higher for group STF (2517 m) than for group CTF (844 m) (P<.05). CONCLUSIONS Complete-arch implant frameworks designed for load application and fabricated by using the passive fit procedure decreased the strain between the frameworks and implants more than 1 piece prefabricated machined frameworks. Precision of fit between frameworks and supporting dental implants in immediately loaded protocols reduces the strain transfered to the peri-implant bone that may impair healing or generate micro-gaps. Purpose. This study investigated the microstrain between premachined one-piece screw-retained frameworks (STF) and screw-retained frameworks constructed by the procedure of cementing titanium cylinders to the pre-fabricated framework (CTF), which has been developed for correction of misfit between framework and immediately loaded implants. Material and methods. Four internal hex cylindrical implants were placed 10 mm distant to each other in a polyurethane block, using surgical guides of the corresponding implant system. Previously fabricated titanium frameworks (N=10) were distributed into 2 groups. While in group STF, pre-fabricated machined frameworks were used (n=5), in group CTF, the frameworks were constructed by a passive fit procedure, which has been developed for correction of misfit between cast titanium frameworks and supporting dental implants (n=5).CTF system was cemented first in the final cast and then screw retained to the implants. Both groups were screw-retained under torque control (10 N/cm). Six strain gauges were placed on the upper surface of the polyurethane block and 3 strain measurements...
PURPOSE: To analyze the torque application on prosthetic abutment screws using different maintenance times, to determine an influence on the removal torque values. MATERIALS AND METH-ODS: A total of 40 external hexagon implants, 40 titanium screws, and 40 customized abutments were used. In group 1, the screws received a torque of 30 N·cm by instant torque application; in groups 2, 3, and 4, torque of 30 N·cm was applied and maintained for 10, 20, and 30 seconds, respectively. Removal torque was performed 10 minutes after torque application. Data were statistically analyzed using 1-way ANOVA and Tukey HSD test ( = 0.05). RESULTS: The mean and standard deviation (±SD) of removal torque values found were 11.61 ± 1.43 N·cm for group 1; 18.64 ± 1.71 N·cm for group 2; 21.62 ± 0.97 N·cm for group 3; and 21.48 ± 1.55 N·cm for group 4. Groups 3 and 4 exhibited statistically higher values than group 2, which demonstrated significantly higher values than group 1 (P < 0.05). CONCLU-SIONS: A torque of 30 N·cm applied for 20 seconds seemed to be the best option when considering the removal torque values of external hexagon implants. DOI: https://doi.org/10.1097/ID.0b013e31829e548dPosted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-89919 Accepted Version Originally published at: Sella, Gustavo Castellazzi; Lopes Pereira Neto, Armando Rodrigues; Maziero Volpato, Cláudia Angela; de Vasconcellos, Diego Klee; Pekkan, Gurel; Özcan, Mutlu (2013). Influence of different maintenance times of torque application on the removal torque values to loosen the prosthetic abutment screws of external hexagon implants. Implant Dentistry, 22 (5) ABSTRACT: (178 WORDS)Purpose: To analyze the torque application on prosthetic abutment screws using different maintenance times, to determine an influence on the removal torque values. Materials and Methods:A total of 40 external hexagon implants, 40 titanium screws and 40 customized abutments were used. In group 1, the screws received a torque of 30 Ncm by instant torque application; in groups 2, 3 and 4, torque of 30 Ncm was applied and maintained for 10, 20 and 30 seconds, respectively. Removal torque was performed 10 minutes after torque application.Data were statistically analyzed using one-way ANOVA and Tukey's HSD test (α = .05). Results:The mean and standard deviation (±SD) of removal torque values found were 11.61±1. The screw loosening may be related to several factors, including: screw tightening, quality of the prosthetic components, screw design, plastic deformation of contact surfaces and lack of passive fit. [10][11][12][13][14][15][16] To prevent this problem, a number of modifications have been used, including modification of the implant body abutment interface (external or internal hexagon or octagon), use of gold screws, torque-controlling devices, screw cements, and the use of a silicone obturator and washers between the prostheses and screws. 1,5,7,8,17,18 Also, centering the occlusal contact, flattening cuspal inclin...
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