Closed Repair Technique: Innovative Surface Design for Polymethylmethacrylate Denture Base Repair.

PURPOSE: This study aimed to evaluate the repair strength of a newly introduced repair technique involving zero-gap repair width. MATERIALS AND METHODS: A total of 36 rectangular prism specimens with dimensions of 64 × 10 × 3.3 mm were prepared from heat-polymerized acrylic resin. Nine specimens were kept intact. The other specimens were sectioned into halves and modified to create repair gaps of 2.5-mm beveled (2.5B) as control, 0-mm beveled (ZB), and 0-mm inverse bi-beveled (ZIBB). The ZIBB group was prepared with a V-shaped internal groove on both halves (repair tunnel), while the intaglio and cameo surfaces were kept intact except for two small holes at the cameo surface for repair resin injection. The 2.5B and ZB groups were repaired conventionally while the ZIBB group was repaired by injecting repair resin into the tunnel through one of the holes until excess material oozed from the other hole. Repaired specimens were thermally cycled at 5 and 55°C for 10,000 cycles with 1 min dwell time. A 3-point bending test was conducted using a universal testing machine for flexural strength and elastic modulus measurement. Kruskal-Wallis/Mann-Whitney tests and ANOVA/post hoc Tukey tests were applied for data analysis (α = 0.05). RESULTS: The flexural strength of repaired specimens was substantially lower than that of intact specimens, and significant differences were present between repaired groups (p ˂ 0.05). ZB and ZIBB had higher flexural strength (p ˂ 0.001) and elastic modulus (p ˂ 0.05) than 2.5B. Among the ZB and ZIBB groups, ZB showed the highest flexural strength, and ZIBB had the highest elastic modulus. CONCLUSION: The closed repair technique improved the flexural strength and elastic modulus of repaired acrylic denture base.

Influence of Different Repair Acrylic Resin and Thermocycling on the Flexural Strength of Denture Base Resin.

Background and Objectives: Fractured acrylic denture base is a common occurrence in clinical practice. The effective denture repair procedure is cost-effective, time conserving, and results in lesser time without denture for the patient. Along with various reinforcements and surface modifications; different acrylic resins are investigated in improving the flexural strength of the fractured site. The aim of this study was to evaluate the flexural strength of a polymethyl methacrylate (PMMA) denture base repaired with heat-polymerized (HPA), auto-polymerized (APA) and light-polymerized acrylic (LPA) resins after thermocycling. Materials and Methods: Forty rectangular shaped (50 mm × 25 mm × 3mm) PMMA specimens were fabricated. Group 1 specimens (n = 10) were kept as controls and the remaining 30 samples were sectioned at the center with a repair site dimension of 3 mm. The samples from three groups (n = 10) were repaired with HPA, APA, and LPA resins, respectively. The specimens were thermocycled for 5000 cycles and subjected to a three-point flexural test. The maximum load required to fracture the specimens was recorded, and further analyzed with ANOVA and the Games-Howell Post hoc test at the significance level p = 0.05. Results: The average maximum load and flexural strength of the control group was 173.60 N and 13.02 Mpa and corresponding values for denture repaired with HPA was 87.36 N and 6.55 Mpa. The corresponding values for APA resin and LPA resins were 62.94 N, 57.51 N, and 4.72 Mpa, 4.06 Mpa, respectively. Conclusions: The PMMA specimens repaired with HPA resins resulted in a significantly higher load to fracture compared to APA resin and LPA resin.

Implant Placement under Existing Removable Dental Prostheses and the Effect on Follow-Up and Prosthetic Maintenance.

PURPOSE: The aim of this prospective clinical study was to compare the maintenance interventions required for solely implant-retained overdentures (I-OD) with that of overdentures retained by a combination of telescopic crowns and implants (T/I-OD). MATERIALS AND METHODS: The participants in this study were 22 patients who initially presented either with a removable complete denture (n = 11) or with an overdenture retained by 1 to 2 telescopic crowns on natural teeth (n = 11). Subsequently, the total number of abutments was increased to 5 to 6 (maxilla) or 4 to 5 (mandible) by placing implants in strategically advantageous regions, generating two distinct groups: I-OD and T/I-OD. Ball attachments were connected to the implants and integrated into the existing denture. The maintenance aspects were analyzed according to the type of treatment (preventive, biological, and technical) and to the severity of treatment (minimal, moderate, and extensive). RESULTS: During a mean observation time of 6.5 years, the tooth survival rate was 89% (T/I-OD) and the implant survival rate 100% (both groups). The survival rates of the overdentures ranged from 90.9% (I-OD) to 100% (T/I-OD). A mean number of 0.6 (I-ODs) and 2.0 (T/I-OD) treatments were performed for biological reasons; and 8.2 (I-ODs) and 9.6 (T/I-OD) for technical reasons, per patient, during the observation time. From biological aspects, significantly more extensive maintenance was found to be necessary in the T/I-OD group than in the I-OD group. CONCLUSIONS: The therapeutic concept of implant placement under existing prostheses was promising when performed in indicated cases.

Comparative Evaluation of the Strength of Denture Base Resin repaired with Glass Fiber-reinforced Acrylic Resin: An in vitro Study.

AIM: The present study aimed at evaluating and comparing the transverse strength of heat polymerizing acrylic resin samples repaired using glass fiber-reinforced autopolymerizing acrylic resin with varying gap widths at the fracture site. MATERIALS AND METHODS: Heat polymerizing acrylic resin samples of dimensions 65 * 10 * 2.5 mm each were fabricated. Ten of these were used as control. In the rest of samples, two grooves were fabricated and surface treated with ethyl acetate. The repair gap width was standardized at 4, 3, 2, and 1 mm. Totally, 80 samples were equally divided into these four groups. Glass fiber-reinforced autopolymerizing acrylic resin was used to repair these samples. The repaired samples and the control groups were subjected to three-point bending test, and the findings were analyzed statistically. RESULTS: It was observed that with increase in gap width, their transverse strength decreased. Most of the fractures occurred at the joint interface of parent and repair material. The fracture within the repaired material occurred highest in the group that had 4 mm gap, followed by groups that had 3 and 2 mm gaps. In the group with 1 mm gap, there was no occurrence of fracture within the repaired material. CONCLUSION: To achieve optimum repair strength of a repaired denture, the gap width should not be greater than 1 mm. CLINICAL SIGNIFICANCE: The study will aid in determining the ideal gap width for denture repair to prevent fracture and also the clinical application of glass fiber-reinforced autopolymerizing acrylic resin.

Modification of clinically short Locator abutments using laser welding.

As dental implants continue to survive longer, managing and maintaining implant prostheses can be complicated by the lack of compatible parts or the discontinuation of implant systems. This report describes a laser welding procedure for the management of clinically short Locator abutments (Zest Anchors Inc) that lacked a commercially available, compatible alternative.

Restauración de molares endodonciados, con resina híbrida sobre muñón de amalgama. A propósito de un caso / Restoration of endodontic molars with hybrid resin over amalgam stump. About a case

Introducción: En la actualidad la restauración funcional y estética de dientes endodonciados con gran pérdida de tejido dentario, es efectuada a través del método indirecto; sin embargo, la construcción de muñones de amalgama como elemento de sustitución de metal es una opción terapéutica viable. Objetivo: Mostrar la viabilidad de la restauración estética y funcional de molares endodonciados y con gran pérdida de tejido dentario, por vía directa mediante resina híbrida sobre muñón de amalgama. Presentación del caso: Tratamiento impuesto a un paciente de 35 años con antecedentes de traumatismo dentario condicionantes de fracturas complicadas de corona en 36 y 37, tratados con endodoncias radicales de 2 años de evolución. Acudió a la consulta presentando pérdidas de más de dos tercios del tejido coronal en ambos casos. Luego de comprobar que ambos molares cumplían con los requerimientos, se realizó la preparación de las cavidades, seguida de la confección de muñones de amalgama, sobre los cuales pasadas las 48 horas, se realizó la restauración definitiva con resina híbrida nano composite. Conclusiones: El tratamiento cosmético con nano composite sobre muñón de amalgama, resulta una alternativa terapéutica viable en la restauración estética y funcional por vía directa, aun en molares con gran pérdida de tejido dentario y tratamiento pulporadicular radical(AU)

Introduction: Nowadays functional and aesthetic restoration of endodontic teeth with a great loss of dental tissue, is performed by means of an indirect method, however the construction of amalgams stumps as an element for the metal substitution is a viable therapeutic option. Objective: To show the viability of endodontic molars aesthetic and functional restoration with a great loss of dental tissue, through direct method with resin on amalgam stump. Case Presentation: Treatment applied to a 35-year-old patient with antecedents of traumatism conditioning complicated fractures of crown in 36 and 37, treated with radical endodontic therapy 2 years ago. Arrived to the consulting room presenting losses of more than two thirds of the coronal tissues in both cases. After verifying that both molars met the requirements, the cavities were prepared, followed by the conformation of amalgams stumps over which after 48h, was applied a nano hybrid resin for the definitive restoration. Conclusions: The cosmetic treatment with Nano composite resin over the amalgam stump is an alternative and viable therapy for the functional and aesthetic restoration by means of a direct procedure, even in molars with great loss of dental tissue and subjected to radical endodontic therapy(AU)

Completely digital approach to fabricating a crown under an existing partial removable dental prosthesis by using an intraoral digital scanner in a single appointment.

Retrofitting a crown to an existing partial removable dental prosthesis (PRDP) is difficult, labor intensive, and time consuming. This article presents an alternative technique for fabricating a crown under an existing PRDP by using an intraoral digital scanner and computer-assisted design and computer-aided manufacturing (CAD/CAM) technology. This technique involves less human error and provides a well-fitting restoration.

An in vitro study of the effect of design of repair surface on the transverse strength of repaired acrylic resin using autopolymerizing resin.

STATEMENT OF PROBLEM: The fracture of complete denture is a common occurrence in the field of prosthodontics. Often if all other criteria are met such as good aesthetics, occlusion, and functionality; denture repair is acceptable. Once denture fractures, we would want the joint surface strength to be as good as original. PURPOSE: The purpose of this study was to determine the effect of different repair surface design on the transverse strength of repaired acrylic denture resin. MATERIALS AND METHODS: Sixty specimens of heat-cured acrylic resin of dimension 65 mm × 20 mm × 2.5 mm were prepared using a special die. Transverse strength of 15 samples was calculated which serves as a control group. Three different types of joint surface contours were prepared each having 15 samples each as butt, round, and rabbet joint. Transverse strength of three joint contours was then compared with control group and also they were compared with each other and result was statistically analyzed with one-way analysis of variance (ANOVA) and Post-hoc ANOVA Tukey's HSD test at 5% level of significance. Z-test of proportion was also done for types of failures. RESULT: Transverse strength of original specimen was higher than that of repaired specimens. Transverse strength of round joint was higher than the butt and rabbet joint. CONCLUSION: Methods of repair have significant effect on strength of repaired denture. Round joint design of repair technique was far superior.

Alternativa estética con la utilización de resinas compuestas ante la pérdida de un diente: presentación de un caso / Aesthetic alternative using composite resin to replace a missing tooth: a case report

Frecuentemente, en los casos de trauma dentario donde se pierde definitivamente un diente, los pacientes son rehabilitados protésicamente por cualquiera de sus variantes. Pero no es muy común que un paciente sea rehabilitado con resina compuesta ante la pérdida de un diente. Se presenta el caso de una paciente que años antes había perdido un incisivo central superior, cuyo espacio había sido tomado por el incisivo lateral; a partir del agrandamiento del mismo se conformó el incisivo faltante, mediante la técnica de restauración directa por estratificación o capas, utilizando la resina Brilliant New Line. El objetivo de este trabajo es demostrar una alternativa más económica y fácil de realizar en nuestras consultas por los estomatólogos, con el objetivo de restaurar la estética de un paciente con pronóstico desfavorable(AU)

Patients who experience dental trauma resulting in permanent tooth loss are often prosthetically rehabilitated through any of its variants. However, it is uncommon to rehabilitate a patient using composite resin when a tooth is lost. The case of a patient who had lost a maxillary central incisor years ago and its space had been occupied by the lateral incisor is presented. The missing tooth was built up through the enlargement of the lateral incisor using the layering technique or stratification with Brilliant New Line resin. This paper aims at demonstrating a more economical and simpler alternative for restoring the aesthetics of a patient with unfavorable prognosis(AU)

Comparison of joint designs for laser welding of cast metal plates and wrought wires.

The purpose of the present study was to compare joint designs for the laser welding of cast metal plates and wrought wire, and to evaluate the welded area internally using X-ray micro-focus computerized tomography (micro-CT). Cast metal plates (Ti, Co-Cr) and wrought wires (Ti, Co-Cr) were welded using similar metals. The specimens were welded using four joint designs in which the wrought wires and the parent metals were welded directly (two designs) or the wrought wires were welded to the groove of the parent metal from one or both sides (n = 5). The porosity and gap in the welded area were evaluated by micro-CT, and the maximum tensile load of the welded specimens was measured with a universal testing machine. An element analysis was conducted using an electron probe X-ray microanalyzer. The statistical analysis of the results was performed using Bonferroni's multiple comparisons (α = 0.05). The results included that all the specimens fractured at the wrought wire when subjected to tensile testing, although there were specimens that exhibited gaps due to the joint design. The wrought wires were affected by laser irradiation and observed to melt together and onto the filler metal. Both Mo and Sn elements found in the wrought wire were detected in the filler metal of the Ti specimens, and Ni was detected in the filler metal of the Co-Cr specimens. The four joint designs simulating the designs used clinically were confirmed to have adequate joint strength provided by laser welding.

Reinforcement of an existing implant-retained complete dental prosthesis for use in compensatory techniques by a patient missing an upper limb.

The purpose of this article is to describe the adaptation of a method suggested for prevention of fractures of partial removable dental prostheses to the reinforcement of an existing implant-retained fixed complete dental prosthesis (IRFCDP). The patient, an upper limb amputee, had subjected the original IRFCDP to parafunctional forces generated from use as a replacement hand in a compensatory technique commonly taught in rehabilitation. Advantages of the technique are that it provides an alternative to remaking the entire prosthesis, which was otherwise satisfactory; it adapts to a variety of situations involving anterior tooth reinforcement; and it offers a potential solution to anterior prosthetic tooth damage caused by other types of parafunction. It may also be adaptable to the reinforcement of other types of prostheses. A disadvantage is the possible need to provide a new interim prosthesis or modify an existing one while laboratory repair procedures are completed. Following reinforcement of the IRFCDP, no tooth damage was evident after one year of use. (J Prosthet Dent 2012;107:343-345).

Effect of ridge-lap surface treatments on the bond of resin teeth to denture base.

PURPOSE: To test in vitro the shear bond strength of resin teeth to an acrylic resin denture base given different ridgelap surface treatments. MATERIALS AND METHODS: Ninety rectangular dies were made with wax and traditionally invested in metallic or plastic flasks. The stone molds were covered with silicone, in which were included an acrylic molar with a wax stick fixed on the ridge lap surface. After deflasking, the wax sticks were removed, the teeth were cleaned with detergent, the ridge lap surface was submitted to different treatments (unmodified, bur-cut grooves, aluminum oxide particle sandblasting, monomer swelling, and primer swelling), and the teeth were replaced in the silicone molds. Metallic flasks were placed in a thermopolymerizing unit to polymerize heat-curing denture-base polymer, and plastic flasks were placed in a domestic microwave oven at 900 W to polymerize microwaveable denture base polymer. After deflasking, the specimens were submitted to the shear bond test in an Instron machine at a cross-speed of 1 mm/min. Results were submitted to ANOVA and Tukey's test (5%). RESULTS: Shear bond strength values were influenced by the ridge-lap surface treatments only in the microwaved polymer. Sandblasting + monomer swelling and sandblasting + primer swelling interactions yielded lower strengths for microwaved polymer. Only the unmodified surfaces presented a significant difference when the resins were compared, where the microwaved polymer showed a higher value. CONCLUSION: Different tooth ridge-lap surface treatments promoted different strengths of the tooth/resin bond.

Flexural strength of acrylic resin repairs processed by different methods: water bath, microwave energy and chemical polymerization.

UNLABELLED: Denture fractures are common in daily practice, causing inconvenience to the patient and to the dentists. Denture repairs should have adequate strength, dimensional stability and color match, and should be easily and quickly performed as well as relatively inexpensive. OBJECTIVE: The aim of this study was to evaluate the flexural strength of acrylic resin repairs processed by different methods: warm water-bath, microwave energy, and chemical polymerization. MATERIAL AND METHODS: Sixty rectangular specimens (31x10x2.5 mm) were made with warm water-bath acrylic resin (Lucitone 550) and grouped (15 specimens per group) according to the resin type used to make repair procedure: 1) specimens of warm water-bath resin (Lucitone 550) without repair (control group); 2) specimens of warm water-bath resin repaired with warm water-bath; 3) specimens of warm water-bath resin repaired with microwave resin (Acron MC); 4) specimens of warm water-bath resin repaired with autopolymerized acrylic resin (Simplex). Flexural strength was measured with the three-point bending in a universal testing machine (MTS 810 Material Test System) with load cell of 100 kgf under constant speed of 5 mm/min. Data were analyzed statistically by Kruskal-Wallis test (p<0.05). RESULTS: The control group showed the best result (156.04±1.82 MPa). Significant differences were found among repaired specimens and the results were decreasing as follows: group 3 (43.02±2.25 MPa), group 2 (36.21±1.20 MPa) and group 4 (6.74±0.85 MPa). CONCLUSION: All repaired specimens demonstrated lower flexural strength than the control group. Repairs with autopolymerized acrylic resin showed the lowest flexural strength.

Flexural strength of acrylic resin repairs processed by different methods: water bath, microwave energy and chemical polymerization

Denture fractures are common in daily practice, causing inconvenience to the patient and to the dentists. Denture repairs should have adequate strength, dimensional stability and color match, and should be easily and quickly performed as well as relatively inexpensive. OBJECTIVE: The aim of this study was to evaluate the flexural strength of acrylic resin repairs processed by different methods: warm water-bath, microwave energy, and chemical polymerization. MATERIAL AND METHODS: Sixty rectangular specimens (31x10x2.5 mm) were made with warm water-bath acrylic resin (Lucitone 550) and grouped (15 specimens per group) according to the resin type used to make repair procedure: 1) specimens of warm water-bath resin (Lucitone 550) without repair (control group); 2) specimens of warm water-bath resin repaired with warm water-bath; 3) specimens of warm water-bath resin repaired with microwave resin (Acron MC); 4) specimens of warm water-bath resin repaired with autopolymerized acrylic resin (Simplex). Flexural strength was measured with the three-point bending in a universal testing machine (MTS 810 Material Test System) with load cell of 100 kgf under constant speed of 5 mm/min. Data were analyzed statistically by Kruskal-Wallis test (p<0.05). RESULTS: The control group showed the best result (156.04±1.82 MPa). Significant differences were found among repaired specimens and the results were decreasing as follows: group 3 (43.02±2.25 MPa), group 2 (36.21±1.20 MPa) and group 4 (6.74±0.85 MPa). CONCLUSION: All repaired specimens demonstrated lower flexural strength than the control group. Repairs with autopolymerized acrylic resin showed the lowest flexural strength.

Aesthetic rehabilitation of an existing PFM bridge.

It is not always possible to simply replace a defective restoration in every clinical situation. In certain cases, replacement of a restoration may not be an acceptable choice. As this case demonstrated, it is possible to replace a lost tooth, mask a discoloration, and add to existing porcelain restorations. Adhesive bonding chemistry has allowed dentists to become innovators in restoration and rehabilitation of a compromised restoration.

Effect of surface treatments and cyclic loading on the bond strength of acrylic resin denture teeth with autopolymerized repair acrylic resin.

STATEMENT OF PROBLEM: Fracture of denture teeth from the denture base is a common problem associated with dental prostheses. Fractured tooth surfaces treated with chemical agents and mechanical features have the potential for improved repair strength. PURPOSE: The purpose of this study was to compare bond strengths of denture teeth to autopolymerized repair acrylic resin after various surface treatments, before and after cyclic loading. MATERIAL AND METHODS: Mandibular lateral incisor denture teeth were selected and ground on the ridge-lap portion using a standardized jig. Specimens with a ground surface were used as controls. The experimental groups included: ground plus airborne-particle abraded, ground plus diatoric recess, and ground plus an experimental bonding agent. The teeth were affixed by an autopolymerized repair acrylic resin to denture bases. Specimens (n=10) were subjected to compression testing (5 mm/min) at a 135-degree angle, before and after 14,400 loading cycles at 2 Hz and 22 N. Peak load to dislodgement was recorded and statistically analyzed (2-way ANOVA, Tukey HSD, alpha=.05). The specimens were then examined using x10 magnification, and fractures were categorized as adhesive, cohesive, or mixed. RESULTS: The mean bond strengths ranged from 26.3 N to 44.2 N. There were no significant differences in fatigue versus nonfatigue strength values within each group (P=.244). Significant strength differences were found (P<.001) between the ground control, diatoric recess, and bonding agent groups. Microscopic examination revealed that the bonding agent group obtained the highest percentage of mixed-type fractures. CONCLUSIONS: The use of a bonding agent and the placement of a diatoric recess in the denture tooth resulted in higher bond strengths than grinding alone. Cyclic loading had no significant impact on the bond strength of denture teeth to the autopolymerized repair acrylic resin.

A modified method for rebasing implant-retained overdentures.

There is a constant need for rebasing implant-retained overdentures because of the inevitable continuous absorption of the underlying residual ridge, which results in a lack of proper occlusion and possible rotation of the denture around the retentive components. This step-by-step article describes all of the clinical and laboratory procedures needed for rebasing a mandibular implant overdenture retained with a bar on two implants, securing an accurate fit. This procedure can be applied successfully for rebasing overdentures with different superstructures (ball attachments or magnets), and for replacing worn or damaged retentive components and matrices.