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Additive manufacturing procedures for fabricating interim restorations include rinsing postprocessing procedures. However, the impact of different rinsing solutions and times on flexural strength is unknown. The purpose of this in vitro study was to assess the influence of the rinsing solutions and duration, as well as accelerated aging (thermocycling) procedures, on the flexural strength and Weibull characteristics of an additively manufactured interim dental material. A bar design (25×2×2 mm) file was used to fabricate all the specimens with 3D printing and an interim material (Nextdent C&B MFH). Five groups were created based on the rinsing solution used during the postprocessing procedures: 91% isopropyl alcohol (IPA) (control or IPA-91), 99% IPA (IPA-99 group), bio-ethyl alcohol 100% (BE group), tripropylene glycol monomethyl ether (TPM) 100% (TPM group), and water miscible formula (Resinaway) (RA group). Each group was divided into 4 subgroups depending on the total rinsing time: 5, 6, 7, and 8 minutes (5, 6, 7, and 8 subgroups). Additionally, each subgroup was distributed between nonaged and aged thermocycling procedures (n=10). Flexural strength measurements were made by using a universal testing machine. Two-parameter Weibull distribution values, including the Weibull modulus, scale (m), and shape (0), were calculated. Three-way ANOVA and pairwise multiple comparison Tukey tests were used to analyze the data (α=.05). Three-way ANOVA showed that the rinsing solution (P <.001), rinsing time (P =.004), and thermocycling procedures (P <.001) were significant predictors of the flexural strength values obtained. The IPA-91 and IPA-99 groups obtained the highest flexural strength, while the RA, TPM, and BE groups obtained the lowest flexural strength. The 7- and 8-minute subgroups obtained the highest flexural strength, while the 5-minute subgroup obtained the lowest flexural strength. The nonaged specimens obtained significantly higher mean flexural strength values than the aged specimens. The vat-polymerized additively manufactured interim dental material tested with differing rinsing solutions and times demonstrated significant differences in the flexural strength values measured. Accelerated artificial aging procedures significantly decreased the flexural strength of the vat-polymerized interim dental material tested. [ABSTRACT FROM AUTHOR]

The influence of postpolymerization methods and artificial aging procedures on the fracture resistance and flexural strength of additively manufactured interim polymers remains unclear. The purpose of this in vitro study was to evaluate the effect of the conditions (dry and water- and glycerin-submerged) and time (25, 30, 35, 40, and 45 minutes) of postpolymerization methods with and without artificial aging procedures on the fracture resistance and flexural strength of an additively manufactured interim material. Bar specimens (25×2×2 mm) were manufactured from an interim resin (NexDent C&B MFH N1) with a 3-dimensional printer (NexDent 5100) as per the manufacturer's recommendations. Three groups were created based on the postpolymerization condition: dry (D group) and submerged in a container with water (W group) or glycerin (G group) inside the ultraviolet polymerization machine (LC-3DPrint Box). Each group was divided into 5 subgroups (D1 to D5, W1 to W5, and G1 to G5) depending on the polymerizing time (25, 30, 35, 40, and 45 minutes) (n=20). Each subgroup was divided into nonaged and aged subgroups. The aged groups were treated in a mastication simulator. Fracture strength was measured on a universal testing machine. The flexural strength was calculated as per International Organization for Standardization (ISO) 10477-2018. The Kolmogorov-Smirnov test demonstrated that data were normally distributed. The 3-way ANOVA test was used to analyze the data (α=.05). A significant main effect was found on the fracture strength analysis for each of the 3 factors: postpolymerization condition (F[2, 449]=81.00, P <.001), treatment duration (F[4, 449]=2.84, P =.024), and aging procedure (F [1, 449] =7.62, P =.006). The only significant 2-way interaction was between postpolymerization condition and treatment duration (F[8, 449]=3.12, P =.002). Furthermore, a significant main effect was found on the flexural strength for each of the 3 factors including postpolymerization condition (F[2, 449]=82.55, P <.001), treatment duration (F[4, 449]=2.85, P =.024), and artificial aging procedure (F[1, 449]=6.72, P =.010). The only significant 2-way interaction was between postpolymerization condition and treatment duration (F[8, 449]=3.33, P =.001). Dry postconditions at 25 minutes and nonaged procedures obtained the significantly highest fracture resistance and flexural strength values. Postpolymerization conditions and duration time affected the fracture resistance and flexural strength of the additively manufactured interim material assessed. Artificial aging procedures significantly decreased the fracture resistance and flexural strength of the additively manufactured interim dental material. [ABSTRACT FROM AUTHOR]

The hard- and soft-tissue replacement materials in the traditional workflow for an implant fixed complete denture are acrylic resin and conventional resin denture teeth supported by a rigid substructure. A novel technique is described combining a modified digital complete denture workflow with analog components and systems, allowing the use of multicolored zirconia and 3D-printed resin. In combination with an appropriate metal substructure, a high-quality prosthesis can be fabricated with reduced effort and cost. [ABSTRACT FROM AUTHOR]

Adequate visualization of existing/proposed tooth position, denture base contours, and prosthetic space is critical to treatment planning of dental implants. Multiple techniques exist for fabricating radiographic guides; many involve duplicating the patient’s existing prosthesis or fabricating a new diagnostic template. This article describes a technique that provides anatomic and restorative information by using an existing prosthesis and a radiographic impression method without the need to fabricate a duplicate or new template. [ABSTRACT FROM AUTHOR]

Statement of problem The location of dental implants and the choice of retentive attachments for implant-retained overdentures are selected based on clinician preference, expert opinion, or empirical information. Limited information is available regarding implant position and the effect on the retention and stability of 2-implant mandibular implant overdentures. Purpose The purpose of this investigation was to evaluate the effect of implant location on the in vitro retention and stability of a simulated 2-implant-supported overdenture and to examine the differences among different attachment systems. Material and methods A model that simulates a mandibular edentulous ridge with dental implants in positions that approximate tooth positions, and a cobalt-chromium cast framework attached to a universal testing machine was used to measure the peak load (N) required to disconnect the attachments. Four different types of attachments (Ball/Cap, ERA, Locator, and O-Ring) were used in sequence in various positions on the model to evaluate the effect of implant location on the retention and stability of a simulated 2-implant-retained overdenture. Means were calculated, and differences among the systems, directions, and groups were identified by using a repeated measured ANOVA (α=.05). For differences observed between measurements, the Bonferroni post hoc method at the 5% level of significance was used to determine the location and magnitude of difference. Results The interactions between the attachment system, direction of force, and implant location were statistically significant (P =.01). The vertical retention and horizontal stability of a simulated overdenture prosthesis increased with the distal implant location up to the second premolar, and the anteroposterior stability increased with distal implant location. The attachment type affected retention and stability differently by location. Ball attachments produced the highest levels of retention and stability, followed by Locator (pink), O-Ring, and ERA (orange). Conclusions The retention and stability of a 2-implant simulated overdenture prosthesis is significantly affected by implant location ( P =.01) and abutment type ( P =.01). [ABSTRACT FROM AUTHOR]

An accelerated technique for casting a direct-pattern post and core restoration for use in fixed prosthodontics has been previously described. Similar techniques for use in removable prosthodontics show potential for clinical use, specifically for the fabrication of radicular stud overdenture attachments and their corresponding copings. The procedure uses a chairside technique and readily available components to fabricate a direct, acrylic resin pattern combining the elements of a cast coping with a fixed radicular attachment. This pattern can subsequently be invested, cast, finished and polished, luted, and attached to the removable prosthesis in a single clinical appointment. [Copyright &y& Elsevier]