Flexural strength of repaired denture base materials manufactured for the CAD-CAM technique.

PURPOSE: To evaluate the flexural properties of repaired poly(methylmethacrylate) (PMMA) denture base materials for computer-aided design/computer-aided manufacturing (CAD-CAM) and to compare them with heat-activated polymerized PMMA. METHODS: A total of 288 specimens (65 × 10 × 2.5 mm) were prepared using both CAD-CAM and conventional blocks and repaired using autopolymerizing and visible-light polymerizing (VLC) materials. Microwave energy, water storage and hydroflask polymerization were applied as additional post-polymerization cycles after the repair process. The flexural strength (FS) of the specimens was evaluated using the three-point bending test. Data were evaluated statistically using 2-way ANOVA followed by Bonferroni's correction to determine the significance of differences between the groups (P ≤ 0.05). RESULTS: The FS of the denture base materials for CAD-CAM was significantly higher than that for the heat-activated group (P ≤ 0.05). The FS was significantly highest when microwave energy was used for the post-polymerization cycle. The FS values for all groups repaired with VLC resin were significantly lower than for the autopolymerization group (P ≤ 0.05). CONCLUSION: The flexural properties of denture base materials for CAD-CAM repaired using autopolymerizing acrylic resins can recover by 50-70%. Additional post-polymerization cycles for autopolymerizing repair resin can be suggested to improve the clinical service properties of repaired dentures.

The effects of different surface treatments applied to milled PMMA denture base material on repair bond strength.

The high cost of CAD/CAM systems and materials is a severe economic burden. Therefore, repair of CAD/CAM PMMA, selecting appropriate repair materials, and surface modifications are clinically important. This study aims to evaluate the shear bond strength of PMMA repair materials after various surface treatments on CAD/CAM PMMA denture base material. For this purpose, a total of 480 CAD/CAM PMMA denture base test specimens were manufactured. Then all test specimens were divided into 6 groups, and different surface treatments were applied. Group A: sandblasting, Group B: 4% hydro fluoric acid, Group C: tungsten carbide bur, Group D: dichloromethane + methyl methacrylate mixture, Group E: dichloromethane and methyl methacrylate, Group F: no surface treatment. Each group is then divided into 4 different subcategories; repair processes were performed using; heat-cured acrylic resin (n:20), auto-polymerized acrylic resin (n:20), gingiva composite (n:20), and CAD/CAM PMMA tooth material (n:20). After repairs, thermal aging was applied to half of the test specimens in each subcategory. The shear bond strength value was measured with a universal test device. Sandblasting group showed the highest surface roughness value in all test specimens (p < 0.001). Heat-cured acrylic resin with sandblasting exhibited the highest bond strength, while the untreated gingiva composite resin exhibited the lowest value. Thermal aging decreased bond strength in all repair materials (p < 0.001). Among the surface treatment groups, sandblasting with Al2O3 particles exhibited the highest surface roughness value and repair bond strength. The application of organic solvents to the surface increased the surface roughness and repair bond strength. Applying dichloromethane and methyl methacrylate monomer separately is more effective than applying it as a mixture. The ideal bonding among repair materials was obtained with heat-cured acrylic resin.

Effect of different mechanical surface treatments on flexural strength of repaired denture base / Efecto de diferentes tratamientos superficiales mecánicos sobre la resistencia a la flexión de la base de la dentadura reparada

Aim: To assess the effect of different mechanical surface treatments on flexural strength of repaired denture base. Material and Methods: Sixty bar-shaped specimens of heat-polymerized acrylic resin were fabricated, and divided into six groups (n=10). All specimens, except the positive control group (group PC), were sectioned into halves to create a 1-mm clearance. A negative control group with no surface treatment (group NC) was also considered. Other groups underwent different surface treatments: group Laser; treated with erbium: yttrium-aluminum-garnet (Er:YAG) laser, group APA; airborne-particle abrasion (APA), group APA plus Laser; a combination of laser and APA, and group Bur; bur grinding. After measuring surface roughness (Ra) with a profilometer, all sectioned specimens were repaired by auto-polymerizing acrylic resin, and thermocycled afterward. Three-point bending test was performed by a universal testing machine. Data were statistically analyzed (α=0.05). Results: The mean surface roughness of all experimental groups were significantly higher than that of group NC (p<0.05). The mean flexural strength of all groups was significantly lower than that of group PC (p<0.05). Group B had significantly higher flexural strength than the other surface-treated groups (p<0.05). Group Laser had significantly higher flexural strength than groups APA (p=0.043) and APA plus Laser (p=0.023). No significant difference was found between groups APA and APA plus Laser (p=0.684). Conclusion: All surface treatments increased the surface roughness and flexural strength compared with the untreated group. The highest flexural strength was observed in specimens treated by bur grinding and then laser, however, it was still significantly lower than intact specimens.

Objetivo: Evaluar el efecto de diferentes tratamientos superficiales mecánicos sobre la resistencia a la flexión de la base de la prótesis reparada. Material y Métodos: Se fabricaron sesenta especímenes en forma de barra de resina acrílica termo-polimerizada y se dividieron en seis grupos (n=10). Todas las muestras, excepto el grupo de control positivo (grupo PC), se seccionaron en mitades para crear un espacio libre de 1 mm. También se consideró un grupo de control negativo sin tratamiento superficial (grupo NC). Otros grupos se sometieron a diferentes tratamientos superficiales: grupo Láser; tratados con láser de erbio: itrio-aluminio-granate (Er:YAG), grupo APA; abrasión por partículas en el aire (APA), grupo APA más láser; una combinación de láser y APA, y grupo Bur; molienda de fresas. Después de medir la rugosidad de la superficie (Ra) con un perfilómetro, todas las muestras seccionadas se repararon con resina acrílica de autopolimerización y se sometieron a termociclado. La prueba de flexión de tres puntos se realizó con una máquina de prueba universal. Los datos se analizaron estadísticamente (α=0,05). Resultados: La rugosidad superficial media de todos los grupos experimentales fue significativamente mayor que la del grupo NC (p<0,05). La resistencia media a la flexión de todos los grupos fue significativamente menor que la del grupo PC (p<0,05). El grupo B tenía una resistencia a la flexión significativamente mayor que los otros grupos tratados en la superficie (p<0,05). El grupo Láser tuvo una resistencia a la flexión significativamente mayor que los grupos APA (p=0,043) y APA más Láser (p=0,023). No se encontró diferencia significativa entre los grupos APA y APA más Láser (p=0,684). Conclusión: Todos los tratamientos superficiales aumentan la rugosidad de la superficie y la resistencia a la flexión en comparación con el grupo sin tratar. La resistencia a la flexión más alta se observó en las muestras tratadas con fresado y luego con láser; sin embargo, aún era significativamente más baja que las muestras intactas.

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.

Fibre-reinforced and repaired PMMA denture base resin: Effect of placement on the flexural strength and load-bearing capacity.

OBJECTIVES: To measure the effect of placement of glass fibre mesh on the flexural strength and load bearing capacity of repaired polymethylmethacrylate (PMMA) denture base resin. MATERIALS AND METHODS: A total of 150 heat-polymerised acrylic resin specimens were fabricated with dimensions of 5 × 30 × 50 mm for flexural strength testing. Specimens were divided into 5 groups according to repair width and placement of the fibre mesh. Three groups (n = 90) had a repair width of 20 mm (including the control group), and two groups (n = 60) had a narrower repair width of 16 mm. Fibre mesh was either embedded at the neutral (bottom of the repair area) or tension (top of the repair area) zone of the specimen when subjected to flexural strength testing. Half of the specimens from each group were subjected to artificial ageing by thermocycling (5 °C and 55 °C, 30s dwell time) for 10,000 cycles to stimulate 12 months in vivo. All the specimens were stored in distilled water at 37 °C for 24 h prior to testing. The flexural strength of the specimen was obtained by three-point bend testing, and data were statistically analysed using ANOVA and post-hoc analysis (SPSS; significance level p < 0.05). Probability of failure was calculated using Weibull analysis. Scanning electron microscopy analysis was used to identify the mode of failure. RESULTS: Specimens repaired with the 20 mm fibre mesh placed in the tension zone showed the highest mean flexural strength (101.33 ± 12.66 MPa) with statistical significance (p = 0.05) to the other groups except for the specimens repaired with the 16 mm fibre mesh placed in the tension zone (p = 0.072). The highest Weibull modulus was found in the thermal cycling group of the specimens with 20 mm repair width repaired with the fibre mesh embedded at the neutral zone (10.01). The lowest Weibull modulus was found in the non-thermal cycling group of the control group (3.15). CONCLUSION: Placing fibre mesh in the tension zone of a PMMA specimen significantly improved the flexural strength of the repair. Placing the fibre mesh in the neutral zone or the fibre mesh width was short of the lower support rollers resulted in no significant increase in flexural strength compared to the non-reinforced control group. Ageing via thermal cycling resulted in a decrease in flexural strength across all sample groups. This study highlights the importance of recognising the valid repair region and to have the mesh embedded in certain dimensions, otherwise it will have no significant contribution towards the repair and increase of flexural strength of the denture.

Alternativas clínicas para el uso de composites Bulk-Fill compactables y fluidos: Reporte de un caso paso a paso / Clinical Alternatives for the Use of Compactable and Flowable Bulk-Fill Composites: A Step-by-Step Case Report

Resumen: El uso de resinas compuestas Bulk-Fill para la restauración de dientes posteriores ha sido masificada en los últimos años en las diferentes disciplinas clínicas de la Odontología. Esto puede deberse principalmente a la simplicidad en la técnica de aplicación de este material ya que requiere de su inserción dentro de la preparación cavitaria en espesores de resina compuesta de hasta 4-5mm, lográndose una reducción considerable de tiempo de trabajo clínico. Ante la existencia de diferentes viscosidades de este tipo de resinas compuestas, ciertas dificultades han sido identificadas ante la selección de cada material Bulk-Fill en relación a las posibles combinaciones que se pueden realizar entre las diferentes marcas disponibles en el mercado, inclusive cuando se usan junto con resinas compuestas convencionales. El objetivo del siguiente reporte de caso, es mostrar dos posibilidades clínicas paso a paso utilizando inicialmente resinas Bulk-Fill compactable en un solo incremento para un segundo molar superior, y luego, a través de la combinación de resinas compuestas Bulk-Fill del tipo fluidas, junto a resinas compuestas Bulk-Fill compactables y resinas compuestas convencionales de estratificación para esmaltes de alto índice de refracción para un primer molar superior.

Abstract: The use of Bulk-Fill composite resins to perform posterior restorations has been massified in recent years in the different clinical disciplines of Dentistry. This may be due mainly to the simplicity in the application technique of this material as it requires its insertion into the cavity preparation in 4-5mm of composite resin thickness, achieving a considerable reduction of clinical working time. Given the existence of different viscosities of this type of composite resins, certain difficulties have been identified before the selection of each Bulk-Fill material related to the possible combinations that can be made between the different brands available in the market, even when they are used with conventional composite resins. The purpose of the following case report, is to present two step-by-step clinical possibilities using initially, compactable Bulk-Fill composite resin in a single increment for the restoration of a second upper molar, and later, through the combination of Bulk-Fill flowable composite resin together with compactable Bulk-Fill composite resin and a high- refractive-index enamel-like conventional composite resin, for a first upper molar.

Evaluation of Transverse Strength of Heat Cure Denture Bases Repaired with Different Joint Surface Contours: An In Vitro Study.

AIM: The present in vitro study aimed to evaluate the transverse strength of heat cure acrylic denture base resins repaired with three different joint surface designs, repair material being the glass-fiber-reinforced self-cure repair material along with surface pretreatment. MATERIALS AND METHODS: A total of 40 heat cure resin specimens were fabricated and finished to a size of 64 mm × 10 mm × 2.5 mm. These specimens were divided into four groups of 10 each, with butt, round, and bevel repair surface joints, respectively, along with the control group. After the specimens were cut in the middle for the repair procedure to proceed, the aforementioned joint surface contours were prepared for groups I, II, and III, respectively, treated with dimethyl chloride for 30 seconds, and the repair was done with E-glass-fiber-reinforced self-cure repair material. RESULTS: The mean transverse strength of the control group was 100.37 N, which was highest (significant p value of <0.05), followed by group III (bevel joint) 54.23 N, group I (butt joint) 53.93 N, and group II (round joint) 44.55 N. CONCLUSION: Distribution of stresses evenly in the repair region will be achieved by the proper selection of the joint surface contour, and this study showed that the 45° bevel joint was an appropriate selection along with promising repair material and surface pretreatment. CLINICAL SIGNIFICANCE: Clinically, in the event of repairing a broken denture, a rapid and economically convenient material with superior physical and mechanical properties is important to maintain the adequate transverse strength of the repaired denture. Glass-fiber-reinforced autopolymerizing resin, with a 45° bevel joint design of the broken surfaces and surface pretreatment proved to reduce stress concentration, improving the transverse strength of the repaired heat cure denture base resins.

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.

Comparative Effect of Glass Fiber and Nano-Filler Addition on Denture Repair Strength.

PURPOSE: To evaluate and compare the effects of glass fiber (GF), Zirconium oxide nanoparticles (nano-ZrO2 ), and silicon dioxide nanoparticles (nano-SiO2 ) addition on the flexural strength and impact strength of repaired denture base material. MATERIALS AND METHODS: Heat-polymerized acrylic resin specimens were fabricated. All specimens were sectioned centrally and beveled creating 2.5 mm repair gap except for 10 controls. Specimen grouping (n = 10/group) was done according to filler concentration of 0%, 0.25%, 0.5%, and 0.75% of auto-polymerized acrylic powder. Modified resin was mixed, packed in the repair gap, polymerized, finished and polished. Three-point bending test and Charpy type impact testing were done. Data were analyzed using one-way-ANOVA and Post-Hoc Tukey test (α = 0.05). RESULTS: All additives significantly increased flexural strength and impact strength (p < 0.05). Within the modified subgroups, no significant differences were found for GF. Significant increase for nano-ZrO2 and significant decrease for nano-SiO2 as the concentration of additive increased were noted for both flexural strength and impact strength. Highest flexural strength was found with 0.75%-nano-ZrO2 (69.59 ± 2.52MPa) and the lowest was found with 0.75%-nano-SiO2 (53.82 ± 3.10MPa). The 0.25%-nano-SiO2 showed the highest impact strength value (2.54 ± 0.21 kJ/m2 ) while the lowest impact strength value was seen with 0.75%-nano-SiO2 (1.54 ± 0.17 kJ/m2 ). CONCLUSION: Nano-filler effect was concentration dependent and its addition to repair resin increased the flexural and impact strengths. The incorporation of 0.75%-ZrO2 or 0.25%-SiO2 into repair resin proved to be a promising technique to enhance repair strength and avoid repeated fractures.

Impact of Surface Treatment with Different Repair Acrylic Resin on the Flexural Strength of Denture Base Resin: An In Vitro Study.

AIM AND OBJECTIVE: The aim and objective of the present study was to assess the flexural strength of denture base resin based on surface treatment with different acrylic resin repair materials. MATERIALS AND METHODS: Totally, 120 heat-polymerized polymethyl methacrylate denture base resin materials which are rectangular shaped with the size of 65 mm × 10 mm × 2.5 mm were fabricated. 150 µm-sized alumina used for surface treatment. All the 120 heat-cured, surface-treated acrylic denture base resin samples were randomly divided into three groups. Group I: glass-fiber-reinforced auto-polymerizing acrylic resin, group II: auto-polymerizing acrylic resin, and group III: light-cured acrylic resin. A universal testing machine was used to test the flexural strength of the repaired specimens. RESULTS: A highest mean flexural strength (88.96 ± 0.31) was demonstrated by group I, followed by group II (72.18 ± 1.86) and group III (66.30 ± 1.02). ANOVA demonstrated a statistically significant inter-group difference. On multiple comparisons, using Tukey's post hoc test a statistically significant difference between groups I and II and between groups I and III was found. CONCLUSION: After considering the limitations, the present study concluded that the highest flexural strength is shown by glass-fiber-reinforced auto-polymerizing acrylic resin than by auto-polymerizing acrylic resin and light-cured acrylic resin. CLINICAL SIGNIFICANCE: Denture repair comprises of joining two fractured parts of a denture with a denture repair material. The success of denture repair depends on the adhesion phenomenon. The treatment of the surface can be accomplished using a suitable material which changes chemically and morphologically and thus promotes better adhesion.

Effect of Repair Gap Width on the Strength of Denture Repair: An In Vitro Comparative Study.

PURPOSE: To evaluate the effect of repair gap width on the flexural strength and impact strength of a repaired acrylic denture with and without thermal cycling. MATERIALS AND METHODS: A total of 240 heat-polymerized acrylic resin specimens were fabricated in dimensions of 65 × 10 × 2.5 ± 0.2 mm and 55 × 10 × 10 ± 0.2 mm for flexural strength and impact strength testing, respectively. All specimens were sectioned into halves then divided into 6 groups according to repair gap width (n = 10). The repair gap of the control group was 2.5 mm at the base, while the repair gaps of the test groups were prepared as 2.0, 1.5, 1.0, 0.5, and 0 mm at the base. All specimens were prepared with a 45° bevel joint. Each specimen was placed into the mold that retained the original length of the specimen and modified only the repair gap, which was packed with repair resin. After polymerization, specimens were finished and polished, and half of the specimens were thermal cycled for 5000 cycles. Three-point bending test and Charpy impact test were used to determine the flexural strength and impact strength, respectively. ANOVA and Tukey's HSD test were used for statistical analysis, where α was set at 0.05. RESULTS: Decreasing repair gap significantly increased the flexural strength in comparison to control group (p < 0.05); 0.5-mm repair gap showed the highest flexural strength values. Changing the repair gap significantly increased the impact strength of groups 2.0- and 1.5-mm (p < 0.05). Thermal cycling significantly decreased the flexural strength of all tested groups as well as impact strength for groups with wide repair gaps (2.5-, 2.0-, and 1.5-mm) (p < 0.05), while other tested groups had nonsignificant effect on impact strength (p > 0.05). CONCLUSION: Decreasing repair gap increased the flexural and impact strengths of repaired acrylic resin. A repair gap of 0-, 0.5-, or 1.0-mm with beveled repair surface is recommended to improve repair strength and overcome the drawbacks of increased amounts of autopolymerized repair 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.

Longitudinal Assessment of Denture Maintenance Needs in an Overdenture Population.

PURPOSE: To evaluate the longitudinal denture maintenance needs of a tooth-supported overdenture population. MATERIALS AND METHODS: This prospective cohort study was composed of patients who had received tooth-supported overdentures from 1974 to 1994 in the Department of Prosthodontics, University of Iowa. There were 272 persons with 662 abutments who fulfilled the inclusion criteria. To simplify analysis and reduce the number of confounding variables, only those participants wearing complete maxillary dentures and opposing complete mandibular overdentures supported by teeth #22 and #27 were included in this analysis. The denture maintenance needs of these participants were identified and related to age, gender, length of time wearing overdentures, number of medications, and denture-wearing habits. Descriptive statistics and bivariate analyses were used for the statistical analysis (α = 0.05). RESULTS: Of the 91 participants (mean age = 59.5 ± 10.1 years; 63.7% male) who fulfilled the inclusion criteria at baseline, 48.4% took 1 to 3 medications daily, and 84.6% wore their dentures day and night. The percentages of participants who needed one or more of the following denture treatments were: 91.2% denture base adjustments, 76.9% laboratory processed relines, 61.5% denture remakes, 33% laboratory remount and occlusal adjustment, 22% repaired bases, and 19.8% needed denture teeth replaced. Bivariate analyses indicated that participants who were 65 years and older needed more denture adjustments than patients younger than 65 years (p = 0.0343). Participants who had worn overdentures for more than 5 years were more likely to require denture remakes (p = 0.0304). Participants who wore their dentures only during the day were less likely to require repairs (p = 0.0403). Participants who did not take any medications were significantly less likely to require denture base repairs (p = 0.0258). For the 35 participants who returned for recalls at all 4 time points, males were more likely to need denture teeth repaired or replaced (p = 0.0335) and those aged 50 to 64 were more likely to need 2 or more adjustments (p = 0.0311). No overdenture abutments were lost by the participants in this study. CONCLUSIONS: According to the results of this study, age, medication usage, denture-wearing habits, and age of the overdentures were significant factors associated with denture maintenance needs. Persons wearing overdentures need regular recalls, because they have continuing maintenance needs.

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.

Survey of Denture Repair Cases: Denture Reinforcement Makes Patients Able to Use Their Dentures for Longer Periods.

PURPOSE: To evaluate the long-term effects of preventive measures against denture fracture using clinical surveys of denture fracture cases from 1984 and 2009. MATERIALS AND METHODS: This study included 128 patients who presented with a chief complaint of denture fracture and received denture repair treatment in 2009. The following data were collected: denture repair procedure; location of denture base fracture (with or without reinforcement); and period of denture use from insertion to repair. Significant differences in characteristics between patients treated in 1984 and 2009 were determined using the chi-square test (P < .05). RESULTS: In 2009, denture fractures comprised 55.5% of all repair cases. The most frequent location of denture fracture was around the clasp and metal in the denture base. Approximately 45% of all dentures were reinforced. The mean period from denture insertion to repair was 37 months. The number of denture fractures significantly decreased between 1984 and 2009 (P < .05), and the number of dentures with reinforcement significantly increased (P < .05). The mean period from denture insertion to repair also increased. CONCLUSION: These findings suggest that denture reinforcement as a preventive measure is effective against denture fracture, allowing patients to use their dentures more effectively.

Diagnosis and treatment of orofacial pain in a patient with unserviceable complete dentures: A clinical report.

An ill-fitting complete denture has the potential to create pain and discomfort as well as conceal or confound the diagnosis of other primary sources of orofacial pain such as trigeminal neuralgia. Guidelines of the American Academy of Orofacial Pain offer an evidence-based approach for the assessment, diagnosis, and management of orofacial pain. A complete and accurate differential diagnosis is paramount to the success of treatment as well as to the circumvention of unnecessary therapy. The purpose of this clinical report was to emphasize an evidence-based approach to the diagnosis and treatment of orofacial pain in a patient with edentulism and a history of prolonged denture wear.

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.

Inhibitory effect of zirconium oxide nanoparticles on Candida albicans adhesion to repaired polymethyl methacrylate denture bases and interim removable prostheses: a new approach for denture stomatitis prevention.

BACKGROUND: Despite drawbacks, cold-cured acrylic resin is still the most common material used in denture repair. Zirconia nanoparticles were among the reinforcements added to increase the strength of the resin. The effect on Candida due to the addition of zirconia nanoparticles to the resin has not been investigated. PURPOSE: The aim of this study was to evaluate the effect of zirconia nanoparticles added to cold-cured acrylic resin on Candida albicans adhesion. MATERIALS AND METHODS: A total of 120 acrylic resin specimens with dimensions measuring 22×10×2.5 mm3 were prepared and divided into two equal groups. One group (repair) comprised heat-polymerized specimens that were sectioned at the center and prepared to create a 2 mm repair area that was repaired with cold-cured resin reinforced with 0% wt, 2.5% wt, 5% wt, and 7.5% wt zirconia nanoparticles. The second group contained intact cold-cured acrylic resin specimens reinforced with 0% wt, 2.5% wt, 5% wt, and 7.5% wt zirconia nanoparticles. Specimens were incubated at 37°C in artificial saliva containing C. albicans, and the effect of zirconia nanoparticles on C. albicans was assessed using two methods: 1) a slide count method and 2) a direct culture test. Variations in the number of living Candida were observed in relation to the different concentrations of zirconia nanoparticles. Analysis of variance (ANOVA) and post hoc Tukey's tests were performed for data analysis. If the P-value was ≤0.05, then the difference was considered as statistically significant. RESULTS: It was found that C. albicans adhesion to repaired specimens was significantly decreased by the addition of zirconia nanoparticles (P<0.00001) in comparison with the control group. Intact cold-cured groups and groups repaired with cold-cured resin reinforced with 7.5% wt zirconia nanoparticles showed the lowest Candida count. Tukey's test showed a significant difference between the repaired group and the intact cold-cured group, while the later demonstrated a lower Candida count. CONCLUSION: The addition of zirconia nanoparticles to cold-cured acrylic resin is an effective method for reducing Candida adhesion to repaired polymethyl methacrylate (PMMA) denture bases and cold-cured removable prosthesis. CLINICAL SIGNIFICANCE: Based on the results of the current study, zirconia nanoparticles have an antifungal effect, which could be incorporated in the repair material for repairing denture bases and in PMMA removable prostheses as a possible approach for denture stomatitis prevention.

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)