First clinical experience with a new non-indwelling voice prosthesis (Provox (R) NID (TM)) for voice rehabilitation after total laryngectomy

Conclusion. The new Provox(R) NID (TM) non- indwelling voice prosthesis investigated in this study provides a good option for laryngectomized patients using non- indwelling voice prostheses and can potentially improve safety and increase patients' satisfaction with their voice and speech. Objective. To investigate the feasibility of and patient satisfaction with the Provox NID non- indwelling voice prosthesis. Material and methods. Pre- and post- study questionnaires were used to evaluate the patients' former voice prosthesis and the Provox NID voice prosthesis. In addition, measurements of pull- out force, maximum phonation time and loudness were made for both voice prostheses. In vitro measurements of airflow characteristics were also made. Following a 6- week trial, all patients provided feedback on the new voice prosthesis and the results were used to further improve the Provox NID. This final version of the new voice prosthesis was subsequently trialled and evaluated by 10 patients 6 months later. Results. Overall results showed that patient satisfaction with the Provox NID non- indwelling voice prosthesis was favourable. The pull- out force for the new prosthesis was significantly higher than that for the formerly used prosthesis and its aerodynamic characteristics were better.

Effect of weathering and thickness on roughness of acrylic resin and ocular button

Purpose: The aim of this study was to evaluate the roughness of colorless ocular button and four brands of colorless acrylic resins designed to fabricate ocular prosthesis as a function of weathering (1008 h) and different thickness (1 and 3.5 mm). Materials and methods: One-hundred-and-twenty specimens were fabricated and distributed in 12 groups. The analysis was carried out by means of digital roughness meter. Results: Data were analyzed statistically by ANOVA and Tukey test at 1% significance. The results showed that there was no statistically significant difference after the weathering period. Both the Vipi Cril acrylic resin with 3.5 mm in thickness and ocular button with 1 mm in thickness presented the lowest roughness values (0.12. Ra). Conclusion: The roughness of the acrylic resins and the ocular button was not affect by the weathering of 1008 h. However, the thickness of the specimens proved to have a major influence on roughness property. © 2010.

Caracterização microestrutural e resistência à corrosão de ligas Co-Cr-Mo utilizadas em próteses dentárias

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise in vitro da proliferação celular e produção de mediadores inflamatórios por células da conjuntiva estimuladas por materiais utilizados na confecção de próteses oculares

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Técnicas de reembasamento para prótese total

Alveolar bone resorption is continuous throughout the life of edentulous patients, the prosthesis mismatch can generate during speech and chewing. An alternative to this would be to destabilize the denture reline, a maneuver which aims to readjust the denture base to the rim by the addition of a plastic film to the inner surface of the prosthesis material. This procedure may be direct, when performed in the clinic, or indirect when made in prosthetic laboratory. The aim this study is to demonstrate the technical of two reline for denture.

FINITE ELEMENT ANALYSIS OF MAXILLARY BONE STRESS CAUSED BY ARAMANY CLASS IV OBTURATOR PROSTHESES

Statement of problem. The retention of an Aramany Class IV removable partial dental prosthesis can be compromised by a lack of support. The biomechanics of this obturator prosthesis result in an unusual stress distribution on the residual maxillary bone. Purpose. This study evaluated the biomechanics of an Aramany Class IV obturator prosthesis with finite element analysis and a digital 3-dimensional (3-D) model developed from a computed tomography scan; bone stress was evaluated according to the load placed on the prosthesis. Material and methods. A 3-D model of an Aramany Class IV maxillary resection and prosthesis was constructed. This model was used to develop a finite element mesh. A 120 N load was applied to the occlusal and incisal platforms corresponding to the prosthetic teeth. Qualitative analysis was based on the scale of maximum principal stress; values obtained through quantitative analysis were expressed in MPa. Results. Under posterior load, tensile and compressive stresses were observed; the tensile stress was greater than the compressive stress, regardless of the bone region, and the greatest compressive stress was observed on the anterior palate near the midline. Under an anterior load, tensile stress was observed in all of the evaluated bone regions; the tensile stress was greater than the compressive stress, regardless of the bone region. Conclusions. The Aramany Class IV obturator prosthesis tended to rotate toward the surgical resection when subjected to posterior or anterior loads. The amount of tensile and compressive stress caused by the Aramany Class IV obturator prosthesis did not exceed the physiological limits of the maxillary bone tissue. (J Prosthet Dent 2012;107:336-342)

Effect of veneering material on the deformation suffered by implant-supported fixed prosthesis framework

The aim of this study was to evaluate the deformation suffered by cantilevered implant-supported fixed prostheses frameworks cast in silver-palladium alloy and coated with two occlusal veneering materials: acrylic resin or porcelain. Material and Methods: Two strain gauges were bonded to the inferior surface of the silver-palladium framework and two other were bonded to the occlusal surface of the prosthesis framework covered with ceramic and acrylic resin on each of its two halves. The framework was fixed to a metallic master model and a 35.2 N compression force was applied to the cantilever at 10, 15 and 20 mm from the most distal implant. The measurements of deformation by compression and tension were obtained. The statistical 2-way ANOVA test was used for individual analysis of the experiment variables and the Tukey test was used for the interrelation between all the variables (material and distance of force application). Results: The results showed that both variables had influence on the studied factors (deformation by compression and tension). Conclusion: The ceramic coating provided greater rigidity to the assembly and therefore less distortion compared with the uncoated framework and with the resin-coated framework. The cantilever arm length also influenced the prosthesis rigidity, causing higher deformation the farther the load was applied from the last implant.

Polymer optoelectronic structures for retinal prosthesis

This commentary highlights the effectiveness of optoelectronic properties of polymer semiconductors based on recent results emerging from our laboratory, where these materials are explored as artificial receptors for interfacing with the visual systems. Organic semiconductors based polymer layers in contact with physiological media exhibit interesting photophysical features, which mimic certain natural photoreceptors, including those in the retina. The availability of such optoelectronic materials opens up a gateway to utilize these structures as neuronal interfaces for stimulating retinal ganglion cells. In a recently reported work entitled ``A polymer optoelectronic interface provides visual cues to a blind retina,'' we utilized a specific configuration of a polymer semiconductor device structure to elicit neuronal activity in a blind retina upon photoexcitation. The elicited neuronal signals were found to have several features that followed the optoelectronic response of the polymer film. More importantly, the polymer-induced retinal response resembled the natural response of the retina to photoexcitation. These observations open up a promising material alternative for artificial retina applications.

Estudo da viabilidade do processo de reciclagem do material descartado do sistema Zirkonzanh® de produção de próteses dentárias

At present, the material of choice for performing aesthetic dental prosthetic work is in the ceramic. Among them, the ceramic base of stabilized zirconia with 3% yttria (3Y - TZP) stand out for having excellent physical and mechanical properties. During the machining of blocks of zirconia in the laboratory to prepare the various types of prostheses, much of the material is given off in the form of powder, which is subsequently discarded. The waste of this material results in financial loss, reflecting higher final cost treatment for patients, as well as damage to the environment, thanks to the processes involved in the manufacture and disposal of the ceramic. This research, pioneered the recycling of zirconium oxide powder obtained during milling of dental crowns and bridges, we highlight the social and environmental aspects and aims to establish a protocol for the reuse of waste (powder of zirconia Zirkonzahn® system) discarded to obtain a new block of compacted zirconia to maintain the same mechanical and microstructural properties of commercial high-cost imported material. To compare with the commercial material, samples were uniaxially (20 MPa) and isostatically (100 MPa), and its mechanical and microstructural characterization was performed through tests of density, porosity, dilatometry, X-ray diffraction (XRD), hardness, fracture toughness, resistance to fracture electron microscopy (SEM) and analysis of grain size. The results observed in the samples were isostatically pressed similiares those obtained with samples from the commercial material demonstrating the viability of the process

Nasalance and nasality at experimental velopharyngeal openings in palatal prosthesis: a case study

The use of prosthetic devices for correction of velopharyngeal insufficiency (VPI) is an alternative treatment for patients with conditions that preclude surgery and for those individuals with a hypofunctional velopharynx (HV) with a poor prognosis for the surgical repair of VPI. Understanding the role and measuring the outcome of prosthetic treatment of velopharyngeal dysfunction requires the use of tools that allow for documenting pre- and post-treatment outcomes. Experimental openings in speech bulbs have been used for simulating VPI in studies documenting changes in aerodynamic, acoustic and kinematics aspects of speech associated with the use of palatal prosthetic devices. The use of nasometry to document changes in speech associated with experimental openings in speech bulbs, however, has not been described in the literature. Objective: This single-subject study investigated nasalance and nasality at the presence of experimental openings drilled through the speech bulb of a patient with HV. Material and Methods: Nasometric recordings of the word "pato" were obtained under 4 velopharyngeal conditions: no-opening (control condition), no speech bulb, speech bulb with a 20 mm(2) opening, and speech bulb with 30 mm(2) opening. Five speech-language pathologists performed auditory-perceptual ratings while the subject read an oral passage under all conditions. Results: Kruskal-Wallis test showed significant difference among conditions (p=0.0002), with Scheffe post hoc test indicating difference from the no-opening condition. Conclusion: The changes in nasalance observed after drilling holes of known sizes in a speech bulb suggest that nasometry reflect changes in transfer of sound energy related to different sizes of velopharyngeal opening.

Implant-retained thumb prosthesis with anti-rotational attachment for a geriatric patient

This report presents the use of a dental implant with an anti-rotational attachment for the retention of a thumb prosthesis. A retention system was manufactured with an attachment (UCLA) screwed into the implant with a two-bar system that was cast in metallic silver palladium. A substructure made from heat-cured acrylic resin was joined to the retention system by clips to join the thumb to the finger (bar clip) in the cast with implant rejoinder. The silicone material, Silastic-MDX 44210, was used to achieve function and aesthetics. Following osseointegration, no skin problems were observed. Whilst the implant-retained digital prosthesis presented some motor limitations, it allowed the patient to return to entertainment and achieve social conviviality.

Effect of Metal-Ceramic or All-Ceramic Superstructure Materials on Stress Distribution in a Single Implant-Supported Prosthesis: Three-Dimensional Finite Element Analysis

Purpose: This three-dimensional finite element analysis study evaluated the effect of different material combinations on stress distribution within metal-ceramic and all-ceramic single implant-supported prostheses. Materials and Methods: Three-dimensional finite element models reproducing a segment of the maxilla with a missing left first premolar were created. Five groups were established to represent different superstructure materials: GP, porcelain fused to gold alloy; GR, modified composite resin fused to gold alloy; TP, porcelain fused to titanium; TR, modified composite resin fused to titanium; and ZP, porcelain fused to zirconia. A 100-N vertical force was applied to the contact points of the crowns. All models were fixed in the superior region of bone tissue and in the mesial and distal faces of the maxilla section. Stress maps were generated by processing with finite element software. Results: Stress distribution and stress values of supporting bone were similar for the GP, GR, TP, and ZP models (1,574.3 MPa, 1,574.3 MPa, 1,574.3 MPa, and 1,574.2 MPa, respectively) and different for the TR model (1,838.3 MPa). The ZP model transferred less stress to the retention screw (785 MPa) than the other groups (939 MPa for GP, 961 MPa for GR, 1,010 MPa for TP, and 1,037 MPa for TR). Conclusion: The use of different materials to fabricate a superstructure for a single implant-supported prosthesis did not affect the stress distribution in the supporting bone. The retention screw received less stress when a combination of porcelain and zirconia was used. Int J Oral Maxillofac Implants 2011;26:1202-1209

THE EFFECT of E-GLASS FIBERS and ACRYLIC RESIN THICKNESS on FRACTURE LOAD IN A SIMULATED IMPLANT-SUPPORTED OVERDENTURE PROSTHESIS

Statement of problem. Implant overdenture prostheses are prone to acrylic resin fracture because of space limitations around the implant overdenture components.Purpose. The purpose of this study was to evaluate the influence of E-glass fibers and acrylic resin thickness in resisting acrylic resin fracture around a simulated overdenture abutment.Material and methods. A model was developed to simulate the clinical situation of an implant overdenture abutment with varying acrylic resin thickness (1.5 or 3.0 mm) with or without E-glass fiber reinforcement. Forty-eight specimens with an underlying simulated abutment were divided into 4 groups (n=12): 1.5 mm acrylic resin without E-glass fibers identified as thin with no E-glass fiber mesh (TN-N); 1.5 mm acrylic resin with E-glass fibers identified as thin with E-glass fiber mesh (TN-F); 3.0 mm acrylic resin without E-glass fibers identified as thick without E-glass fiber mesh (TK-N); and 3.0 mm acrylic resin with E-glass fibers identified as thick with E-glass fiber mesh (TK-F). All specimens were submitted to a 3-point bending test and fracture loads (N) were analyzed with a 2-way ANOVA and Tukey's post hoc test (alpha=.05).Results. The results revealed significant differences in fracture load among the 4 groups, with significant effects from both thickness (P<.001) and inclusion of the mesh (P<.001). Results demonstrated no interaction between mesh and thickness (P=.690). The TN-N: 39 +/- 5 N; TN-F: 50 +/- 6.9 N; TK-N: 162 +/- 13 N; and TK-F: 193 +/- 21 N groups were all statistically different (P<.001).Conclusions. The fracture load of a processed, acrylic resin implant-supported overdenture can be significantly increased by the addition of E-glass fibers even when using thin acrylic resin sections. on a relative basis, the increase in fracture load was similar when adding E-glass fibers or increasing acrylic resin thickness. (J Prosthet Dent 2011;106:373-377)

An Implant-Transfer Technique Without Impression Material

Different transfer impression techniques for implant-supported prostheses have been suggested to obtain a working cast. This article describes and illustrates clinical and laboratory pros-thodontic procedures to transfer implant positions with splinted transfer copings and without impression material to form a laboratory analog transfer template. With this technique, a preliminary cast is modified to place the analogs according to a corrected position and obtain the master cast. Although this technique does not record adjacent tissues, it is a simple procedure, less time consuming, and easily performed.

Esthetic Interim Acrylic Resin Prosthesis Reinforced with Metal Casting

Fabrication of an interim prosthesis is an important procedure in oral rehabilitation because it aids in determining the esthetics, phonetics, and occlusal relationship of the definitive restoration. The typical material (acrylic resin) used in interim prostheses commonly fails due to fractures. During extended oral rehabilitation with fixed partial prostheses, high strength interim prostheses are often required to protect hard and soft tissues, avoid dental mobility, and to allow the clinician and patient a chance to evaluate cosmetics and function before the placement of the definitive prosthesis. Furthermore, a satisfactory interim prosthesis can serve as a template for the construction of the definitive prosthesis. The maintenance of this prosthesis is important during treatment for protection of teeth and occlusal stability. Procedures to reinforce interim prostheses help to improve performance and esthetics in long-term treatment. Due to the low durability of acrylic resin in long-term use, the use of reinforcing materials, such as metal castings or spot-welded stainless steel matrix bands, is indicated in cases of extensive restoration and long-term treatment. This paper describes an easy technique for fabricating a fixed interim prosthesis using acrylic resin and a cast metallic reinforcement.