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.

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.

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.

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.

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.

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.

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 different repair techniques on the accuracy of repositioning the fractured denture base.

OBJECTIVE: This study investigated the efficacy of different techniques for the union of fragments of a denture before repair and on the accuracy of the reposition. MATERIALS AND METHODS: For this study, 20 maxillary dentures made with Lucitone 550 heat-cured resin were used. Points were determined with a scanner on the cusp of the teeth, as a measurement of the segments. After digitisation, each model was exported to the AUTOCAD R 14 program and two-dimensional measurements of the distances between the marked points were made. After the initial analysis, the dentures were fractured into two segments using an impact test machine. For the repair, maxillary dentures were divided into two groups; in the first, the repair was carried out using Kerr's sticky wax and in the second group, Super Bonder was used to join the fragments, with subsequent inclusion of DENTSPLY Repair Material resin. After the repair, the points of the maxillary dentures were measured again. The numerical values obtained were tabulated to compare the measurements before fracture and after the repair. For statistical analysis, analysis of variance was employed, using a single factor and double factor, followed by the Tukey test with a reliability of 95%. RESULTS: The results demonstrated a statistically significant difference between the materials used to join the dentures for repair, where the dentures were joined with sticky wax presented a larger variation in the distances between the points. CONCLUSION: The variation in distances between the points is influenced by the agent of repair.

Strength of denture base resins repaired with auto- and visible light-polymerized materials.

PURPOSE: Clinicians are still confused about the choice of repair method, which depends on factors such as the length of time required for processing, the mechanical strength of the repaired material, and the effect of stress concentration in the acrylic resins before the repair. The aim was to determine the impact and flexural strength characteristics, such as stress at yield, Young's modulus, and displacement at yield of denture base resins fractured and repaired by three methods using heat-, auto-, and visible light-polymerized acrylic resins. MATERIAL AND METHODS: For impact and flexural strength tests, 18 rectangular specimens measuring 50 x 6 x 4 mm(3) and 64 x 10 x 3.3 mm(3), respectively, were processed using Impact 2000, Lucitone 550, Impact 1500, and QC-20 acrylic resins. Fracture tests were performed according to ISO1567:1999. Afterward, all fractured specimens were stored in distilled water at 37 degrees C for 7 days, and then repaired with (1) the same acrylic resin used for specimen fabrication (n = 6), (2) an autopolymerized acrylic resin (TruRepair, n = 6), and (3) a visible light acrylic resin (Versyo.com, n = 6). The repaired specimens were again submitted to the same fracture tests, and the failures were classified as adhesive or cohesive. Data from all mechanical tests after repair by the different methods were submitted to two-way ANOVA, and mean values were compared by the Tukey test. RESULTS: All acrylic resins showed adhesive fractures after impact and flexural strength tests. Differences (p < 0.05) were found among repair methods for all acrylic resins studied, with the exception of displacement at yield, which showed similar values for repairs with auto- and visible light-polymerized acrylic resins. The highest values for impact strength, stress, and displacement at yield were obtained when the repair was made with the same resin the specimen was made of. CONCLUSION: Denture base acrylic resins repaired with the same resin they were made of showed greater fracture strength.

A resin acrylic and plaster solder index technique for realigning an ill-fitting fixed partial denture framework.

A resin acrylic and plaster solder index technique is a simple, accurate, secure, and cost-effective way to intraorally realign an ill-fitting fixed partial denture framework. Once the fixed partial denture framework is sectioned and segments are found to fit, an intraoral index preserves the correct relationship among segments and holds castings together securely enough to avoid separating until they can be embedded in solder investment and soldered in the dental laboratory. This technique is described here, together with a literature review and a discussion of the technique's advantages relative to other indexing techniques and materials.

A resin-bonded overcasting with highly filled composite resin to salvage a broken metal-ceramic fixed partial denture: a case report.

A resin-bonded overcasting made of a silver-palladium-copper-gold alloy with highly filled composite resin was fabricated to salvage a broken metal-ceramic fixed partial denture using a metal conditioner, a silane coupling agent, and an adhesive resin luting cement. This resin-bonded overcasting has been functioning satisfactorily for more than nine years without any problems. The longevity of the fixed partial denture was enhanced through the use of this treatment.

A comparison of acrylic and multilithic teeth bond strengths to acrylic denture base material.

AIM: Debonding of denture teeth from the denture base can be frustrating for both the clinician as well as his or her patients. The wear resistance of composite denture teeth has been well investigated since their introduction, but there have been few studies about the bonding of these teeth to acrylic denture base resins. The aim of this study was to compare the bond strengths of two brands of acrylic and one brand of multilithic denture teeth to acrylic denture base material. METHODS AND MATERIALS: In this experimental-laboratory study, three types of denture teeth--Yaghoot, Super Brilian, and Major--were used. After grinding the glossy ridge lap surfaces, the teeth were mounted on two sides of triangular-shaped wax models. Then the wax elimination and resin processing laboratory procedures were carried out as is done with the fabrication of a complete denture. Each of the specimens was tested using a universal testing machine with a cross head speed of 5 mm/min at an angle of 130 degrees to the long axis of the teeth. The data were analyzed using one-way ANOVA and Chi-square tests. RESULTS: The mean bond strength in the Yaghoot group was 717.43+/-293.59 N while in the Super Brilian group it was 578.40+/-395.38 and in the Major group, 547.95+/-296.75N. However, there was no significant difference between the three groups (p=0.194). CONCLUSION: Although the mean bond strength in the multilithic group was higher than in the other groups, no significant difference was found between the three groups. There was no significant difference between the three groups with regard to the prevalence and type of fracture site. CLINICAL SIGNIFICANCE: The bonding strength of multilithic denture teeth to denture base resins was found to be comparable to, and even slightly higher than, acrylic conventional denture teeth, making them a promising choice for clinicians in the fabrication of removable dentures.