Influence of postpolymerization methods and artificial aging procedures on the fracture resistance and flexural strength of a vat-polymerized interim dental material.

STATEMENT OF PROBLEM: The influence of postpolymerization methods and artificial aging procedures on the fracture resistance and flexural strength of additively manufactured interim polymers remains unclear. PURPOSE: 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. MATERIAL AND METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.

Influence of postprocessing rinsing solutions and duration on flexural strength of aged and nonaged additively manufactured interim dental material.

STATEMENT OF PROBLEM: 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. PURPOSE: 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. MATERIAL AND METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.

Expedited Digital-Analog Hybrid Method to Fabricate a 3D-Printed Implant Overdenture.

The present case report describes a technique to convert an interim mandibular complete dental prosthesis into a digitally designed and additively manufactured implant overdenture prosthesis. A patient had two dental implants placed, an interim complete denture, and a soft reline procedure completed. After implant osseointegration, existing healing abutments were removed, a functionally generated reline impression with polyvinyl siloxane impression material was made. Using an intraoral scanner, a 360-degree optical scan was obtained of the relined interim prosthesis. A new prosthesis was digitally designed using the optical scan, additively manufactured, and housings picked-up intraorally to create an implant-retained overdenture.

Workflow for a metal-resin-zirconia fixed complete denture: A dental technique.

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.

Radiopaque dental impression method for radiographic interpretation, digital alignment, and surgical guide fabrication for dental implant placement.

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.

Comparison of retention and stability of two implant-retained overdentures based on implant location.

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).

Stabilization of a computer-aided implant surgical guide using existing dental implants with conversion of an overdenture to a fixed prosthesis.

This clinical report describes a technique to stabilize a computer-aided dental implant surgical guide to existing implants. A patient requested conversion of her existing mandibular implant-assisted overdenture into a fixed complete denture. The surgical procedure was planned virtually, and the two existing dental implants were integrated into the surgical plan as a means to fixate the surgical guide. The implants were placed, and the patient's prosthesis was converted into an interim fixed complete denture.

CAD/CAM guided surgery in implant dentistry: a brief review.

Advanced imaging and CAD/CAM technologies and their applications in enhancing treatment outcomes in implant dentistry have gained widespread interest. Guided implant surgery utilizing these advanced technologies has significant applications in implant dentistry. This article provides information on some of the perceived advantages and disadvantages for planning guided versus conventional implant surgery as well as basic steps involved in the fabrication of guided surgical templates (GST).

CAD/CAM guided surgery in implant dentistry. A review of software packages and step-by-step protocols for planning surgical guides.

Three-dimensional radiographic imaging for dental implant treatment planning is gaining widespread interest and popularity. However, application of the data from 30 imaging can be a complex and daunting process initially. The purpose of this article is to describe features of three software packages and the respective computerized guided surgical templates (GST) fabricated from them. A step-by-step method of interpreting and ordering a GST to simplify the process of the surgical planning and implant placement is discussed.

Adapting the Digital Reference Denture Technique for Full-Arch Cases Using a Novel Fixed Attachment System.

Digital technology has tremendously impacted implant dentistry and particularly the production of full-arch reconstructions. The use of digital methods to fabricate removable and fixed complete dental prostheses with implants offers many benefits, yet for some clinicians a hybrid method that combines analog and digital techniques for full-arch restorations may be beneficial. This article describes a combination analog-digital method that utilizes the patient's existing removable prosthesis to guide fabrication of a fixed full-arch restoration using a novel stud-style abutment system with a contemporary housing and insert combination.

Dual-Arch Implant Overdenture Treatment Protocols.

Patients who require transitioning from natural teeth to dental implants present a unique challenge to clinicians. When evaluating decisionmaking processes, clinicians must determine the best restorative treatment options for the patient. Fixed and removable treatment options may both become ideal possibilities for a patient, depending on the patient's clinical presentation. Patients who are interested in fixed options but may not have the financial resources to be able to afford this more expensive alternative often may choose removable overdenture solutions. This article discusses ideal treatment planning strategies for patients interested in dual-arch overdenture restorations and reviews a clinical case describing this treatment.

An accelerated clinical chairside technique for casting overdenture attachment copings.

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.

Managing Angulation Challenges With Implant Overdentures.

Proper treatment planning is critical to achieving a successful outcome when treating patients with implant overdenture restorations. Key factors related to success include the number, location, and distribution of implants and choice of abutment. Contemporary design of stud-style abutment systems for overdentures is aimed at accommodating patients who present with challenges such as anatomical limitations or poor dexterity hampering insertion and removal of prostheses. This article describes the effective management of excessive angulation to achieve an enhanced outcome with implant overdenture treatment, even with a less-than-ideal clinical presentation.

A comparison of results from two mycology laboratories for the diagnosis of onychomycosis: a study of 85 cases in a geriatric population.

An investigative study was performed to compare the results from two mycology laboratories for the diagnosis of onychomycosis in a geriatric population and to determine the possible pharmacologic treatments based on the two laboratories' results. In this study, 85 cases of suspected onychomycosis involving men and women 65 years and older from a nursing home setting in South Florida were used. Samples were taken from the hallux toenail and sent to two different mycology laboratories for fluorescent potassium hydroxide preparation and microscopic examination of a fungal culture. Of the 85 cases studied, the two mycology laboratories reported similar potassium hydroxide preparation results for 58.8% of the patients and similar fungal culture results for genus and species identification for 37.6% of the patients. When the potassium hydroxide preparation and fungal culture results were combined, the two mycology laboratories reported similar results for only 27.1% of the patients. As a result of the two mycology laboratories' findings, the possible US Food and Drug Administration-approved pharmacologic treatments may differ for 43.5% of the patients studied. The discrepancy between the two independent laboratories leaves physicians to question the reproducibility of fluorescent potassium hydroxide preparation and fungal culture analysis in a geriatric patient population for the diagnosis of onychomycosis.