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1.
Int Dent J ; 2024 Jul 23.
Artículo en Inglés | MEDLINE | ID: mdl-39043527

RESUMEN

INTRODUCTION AND AIMS: This study aimed to investigate the effects of a developed school-based online health education programme with a periodontal examination results sheet for high school students on their subjective oral symptoms, knowledge and attitudes regarding oral health, and oral health behaviours. METHODS: The participants were first- and second-year students aged 15 to 17 years (n = 847) at a high school in Japan. The students underwent a periodontal examination and were divided into periodontal condition (PC) and nonperiodontal condition (non-PC) groups. The students participated in the online oral health education programme, which included a periodontal examination results sheet after the examination. The data for identifying the effect of the programme were collected via questionnaire surveys at the periodontal examination (baseline), after 3 months, and after 1 year, and they were compared between baseline and 3 months later and between baseline and 1 year later by the chi-square test. Logistic regression analysis was used to determine the associations between the measured variables related to oral health at 3 months or 1 year and the presence/absence of periodontal conditions after adjustment for sex and variables at baseline. RESULTS: A total of 628 students (74.1%) participated in this study. The percentages of individuals with knowledge of how many teeth they had, knowledge of periodontal disease, and experience with toothbrushing instruction increased significantly after 1 year in both groups (p < .05). The awareness of gingival swelling and bleeding and the use of fluoride toothpaste at 3 months were positively associated with the presence of periodontal conditions. CONCLUSIONS: This study showed that an online oral health education programme contributed to improving oral health knowledge and behaviours among high school students and that the awareness of periodontal conditions according to the periodontal examination results sheet might improve the awareness of gingival swelling and bleeding at 3 months.

2.
J Prosthodont Res ; 2024 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-38644230

RESUMEN

PURPOSE: The purpose of this study is to compare the shear bond strength of ultraviolet (UV)-polymerized resin to 3D-printed denture materials, both with and without post-polymerization. Moreover, the effects of surface treatment and thermocycling on shear bond strength after post-polymerization were investigated. METHODS: Cylindrical 3D-printed denture bases and teeth specimens were prepared. The specimens are subjected to two tests. For Test 1, the specimens were bonded without any surface treatment or thermal stress for comparison with and without post-polymerization. In Test 2, specimens underwent five surface treatments: untreated (CON), ethyl acetate (EA), airborne particle abrasion (APA) with 50 µm (50-APA) and 110 µm alumina (110-APA), and tribochemical silica coating (TSC). A UV-polymerized resin was used for bonding. Half of the Test 2 specimens were thermocycled for 10,000 cycles. Shear bond strength was measured and analyzed using Kruskal-Wallis and Steel-Dwass tests (n = 8). RESULTS: In Test 1, post-polymerization significantly reduced shear bond strength of both 3D-printed denture materials (P < 0.05). No notable difference was observed between the denture teeth and the bases (P > 0.05). In Test 2, before thermocycling, the CON and EA groups exhibited low bond strengths, while the 50-APA, 110-APA, and TSC groups exhibited higher bond strengths. Thermocycling did not reduce bond strength in the latter groups, but significantly reduced bond strength in the EA group (P < 0.001). CONCLUSIONS: Post-polymerization can significantly reduce the shear bond strength of 3D-printed denture materials. Surface treatments, particularly APA and TSC, maintained bond strength even after thermocycling.

3.
BDJ Open ; 9(1): 29, 2023 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-37452032

RESUMEN

INTRODUCTION: This study aimed to investigate the prevalence of periodontal disease and the factors of the disease among high school students. METHOD: The participants were all students aged 15-18 years (n = 1202) at a high school in Japan. The data on oral health perceptions and behaviours were collected by a questionnaire survey. The prevalence of periodontal disease among them was investigated with the partial community periodontal index (PCPI). A logistic regression analysis was used to identify the factors associated with the PCPI. RESULTS: A total of 1069 students (88.9%) participated in this study. The prevalence of gingival bleeding, calculus, pocket depth of 4-5 mm, and pocket depth of 6 mm or more were 44.2%, 42.2%, 11.4%, and 1.6%, respectively. Approximately one-third of the students had a fear of dental treatment, and only 28.4% used dental floss. The results of logistic regression analysis, adjusted for sex and school year, showed that not visiting dentists regularly, not using dental floss, brushing teeth for less than 5 min, fear of dental treatment, and drinking sports drinks frequently were positively associated with periodontal conditions. CONCLUSION: This study identified a high prevalence of periodontal disease among Japanese high school students aged 15-18 years and its risk factors, such as poor oral health behaviours and fear of dental treatment.

4.
Dent Mater J ; 40(3): 657-663, 2021 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-33456030

RESUMEN

This research was conducted to investigate the bond strength between artificial teeth and a thermoplastic denture base resin for injection molding with different surface preparations for use in flexible resin removable partial dentures. Composite resin denture teeth and acrylic denture resin teeth were bonded to three types of thermoplastic denture base resins for injection molding (polyamide, polyester, and polycarbonate) and a conventional heat-polymerized polymethyl methacrylate (PMMA) resin (control). The ridge lap surfaces of the artificial teeth were classified into four groups based on the type of ridge lap surface treatment applied (n=10): no treatment, ethyl acetate, small T-shaped tunnel, and large T-shaped tunnel. The specimens were tested for bond strength. The results showed that the ethyl acetate treatment was ineffective for enhancing the bond strength (p>0.05) between the artificial teeth and thermoplastic denture base resin for injection molding, whereas the T-shaped tunnel was quite effective in this regard (p<0.05).


Asunto(s)
Recubrimiento Dental Adhesivo , Diente Artificial , Resinas Acrílicas , Bases para Dentadura , Ensayo de Materiales , Polimetil Metacrilato , Propiedades de Superficie
5.
J Mech Behav Biomed Mater ; 102: 103513, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31689576

RESUMEN

Cellulose nanofiber (CNF) made from wood-derived fiber is considered as a potential alternative reinforcing material to conventional fibers. The aim of this study was to investigate the effect of CNF on the flexural properties of CNF-reinforced, injection molded, polymethyl methacrylate (PMMA) denture base material. Test specimens were fabricated from a model thermoplastic denture base resin using the injection molding technique. The resin pellets were mixed with CNF (to obtain different weight percentages 5, 10, 15, and 23 wt%). PMMA without CNF served as the control (0 wt%). Prior to the testing, the test specimens (n = 12/group) were water-immersed at 37 °C water for 50 h. The flexural strengths and moduli of the specimens were determined using three-point bending tests. Statistical evaluation included a one-way analysis of variance and the Student-Newman-Keuls test (α = 0.05). The mean and standard deviation of flexural strengths with the addition of 0, 5, 10, 15 and 23% CNF were 49.4 (±0.7), 56.4 (±1.3), 63.5 (±2.0), 72.0 (±4.7), and 96.8 (±4.0) MPa, respectively. The mean and standard deviation of flexural modulus with the addition of the same concentrations of CNF were 1.31 (±0.02), 1.56 (±0.05), 1.99 (±0.14), 2.40 (±0.15), and 3.96 (±0.08) GPa, respectively. The flexural strengths and moduli of the CNF-reinforced PMMA were significantly higher than those of pure PMMA (p < 0.05). Hence, incorporation of CNF can significantly improve flexural properties of a thermoplastic PMMA denture base material.


Asunto(s)
Nanofibras , Polimetil Metacrilato , Resinas Acrílicas , Celulosa , Bases para Dentadura , Resistencia Flexional , Humanos , Ensayo de Materiales , Docilidad
6.
J Prosthet Dent ; 120(1): 9-12, 2018 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-29258692

RESUMEN

This clinical report describes the management of a patient who had a metal allergy and had difficulty sitting in a dental chair for an extended period. The presented treatment used an intraoral scanner and computer-aided design and computer-aided manufacturing (CAD-CAM) to fabricate a nonmetal clasp denture. The described procedure may reduce patient discomfort and chair-time.


Asunto(s)
Diseño Asistido por Computadora , Diseño de Dentadura/métodos , Dentadura Parcial Fija , Arcada Parcialmente Edéntula/rehabilitación , Anciano , Abrazadera Dental , Femenino , Humanos , Imagenología Tridimensional , Mandíbula
7.
Int J Prosthodont ; 30(3): 277-279, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28453003

RESUMEN

PURPOSE: The purpose of this study was to fabricate a prototype nonmetal clasp denture using computer-aided design/computer-assisted manufacture (CAD/CAM) technology. MATERIALS AND METHODS: A partially edentulous mandibular working cast was scanned using an optical scanner. A sectional denture separated by two parts was designed on the scanned cast. These parts were milled and combined, and adhered using an adhesive luting agent. RESULTS: The completed denture was delivered on the working cast and provided an excellent level of fitness. CONCLUSION: A prototype nonmetal clasp denture could be fabricated using CAD/CAM technology.


Asunto(s)
Diseño Asistido por Computadora , Diseño de Dentadura , Dentadura Parcial Removible , Arcada Parcialmente Edéntula/rehabilitación , Humanos , Técnicas In Vitro , Proyectos Piloto
8.
J Prosthodont Res ; 61(1): 67-72, 2017 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-27238884

RESUMEN

PURPOSE: This study evaluated the shear bond strength of a chairside autopolymerizing reline resin to injection-molded thermoplastic denture base resins. METHODS: Four kinds of injection-molded thermoplastic resins (two polyamides, a polyethylene terephthalate copolymer and a polycarbonate) and PMMA, as a control, were tested. The eight types of surface treatment: ((1) no treatment, (2) air abrasion, (3) dichloromethane, (4) ethyl acetate, (5) 4-META/MMA-TBB resin, (6) air abrasion and 4-META/MMA-TBB resin, (7) tribochemical silica coating, and (8) tribochemical silica coating and 4-META/MMA-TBB resin) were applied to each specimen. The chairside autopolymerizing reline resins were bonded to disks of the injection-molded thermoplastic denture base resins. All of the specimens were immersed in water for 4 months and then thermocycled for 10,000 cycles in water between 5 and 55°C. The shear bond strengths were determined. RESULTS: The shear bond strengths of the two polyamides treated using air abrasion, dichloromethane and ethyl acetate and no treatment were exceedingly low. The greatest bond strength was recorded for the polyethylene terephthalate copolymer specimens treated with tribochemical silica coating and 4-META/MMA-TBB resin (22.5MPa). The bond strengths of the other injection-molded thermoplastic denture base resins increased using 4-META/MMA-TBB resin. CONCLUSIONS: Tribochemical silica coating and 4-META/MMA-TBB resin were the most effective surface treatments among all denture base resins tested.


Asunto(s)
Recubrimiento Dental Adhesivo , Bases para Dentadura , Ensayo de Materiales , Polimerizacion , Polímeros , Resinas Sintéticas , Resistencia al Corte , Compuestos de Boro , Metacrilatos , Metilmetacrilatos , Nylons , Temperatura
9.
J Prosthodont ; 26(4): 302-308, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-26682773

RESUMEN

PURPOSE: To evaluate the effect of reinforcement on the flexural properties of injection-molded thermoplastic denture base resins. MATERIALS AND METHODS: Three injection-molded thermoplastic denture base resins (polyamide, polyester, polycarbonate) were selected for this study, and a conventional heat-polymerized denture base resin (PMMA) was used as a control. Continuous unidirectional glass fiber-reinforced composite (FRC) and metal wire were used for reinforcement. Reinforced bar-shaped specimens (65 mm long, 10 mm wide, 3.3 mm high) were fabricated (n = 10). The flexural strength at the proportional limit (FS-PL) and the elastic modulus were measured using a three-point bending test. RESULTS: All the denture base material specimens reinforced with FRC possessed a significantly higher FS-PL compared to those without reinforcement. The FS-PL of the polycarbonate specimens reinforced with metal wire was significantly higher than that without reinforcement, and there was no significant difference in the FS-PL between the polycarbonate specimens reinforced with FRC and those with metal wire. The order of the elastic modulus according to the denture base material, arranged in terms of statistical significance, was as follows: PMMA (3.46 ± 0.53 GPa) > polycarbonate (2.69 ± 0.48 GPa) > polyester (2.00 ± 0.39 GPa) > polyamide (1.14 ± 0.35 GPa). The order of the elastic modulus according to the reinforcement, arranged in terms of statistical significance, was as follows: metal wire (2.74 ± 0.96 GPa) > FRC (2.40 ± 0.89 GPa) > no reinforcement (1.82 ± 0.83 GPa). CONCLUSION: Continuous unidirectional glass fiber-reinforced composite (FRC) reinforcement had a satisfactory reinforcing effect for the injection-molded thermoplastic denture base resins.


Asunto(s)
Resinas Acrílicas/química , Bases para Dentadura , Diseño de Dentadura , Análisis del Estrés Dental , Módulo de Elasticidad , Vidrio , Humanos , Ensayo de Materiales , Estrés Mecánico
10.
Dent Mater J ; 35(2): 204-9, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27041009

RESUMEN

The purpose of this study was to investigate the effect of long-term water immersion or thermal shock on the mechanical properties of high-impact acrylic denture base resins. Two high-impact acrylic denture base resins were selected for the study. Specimens of each denture base material tested were fabricated according to the manufacturers' instructions (n=10). The flexural strength at the proportional limit, the elastic modulus and the impact strength of the specimens were evaluated. The flexural strength at the proportional limit of the high-impact acrylic denture base resins did not change after six months' water immersion or thermocycling 50,000 times. The elastic moduli of the high-impact acrylic denture base resins significantly increased after six months' water immersion or thermocycling 50,000 times. The impact strengths of the high-impact acrylic denture base resins significantly decreased after water immersion or thermocycling as described above.


Asunto(s)
Resinas Acrílicas , Bases para Dentadura , Módulo de Elasticidad , Ensayo de Materiales , Estrés Mecánico , Agua
11.
Acta Odontol Scand ; 74(1): 67-72, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-25953322

RESUMEN

OBJECTIVE: The aim of this study was to evaluate the effect of cycling deflection on the flexural behavior of injection-molded thermoplastic resins. MATERIALS AND METHODS: Six injection-molded thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethyl methacrylate) and, as a control, a conventional heat-polymerized denture based polymer of polymethyl methacrylate (PMMA) were used in this study. The cyclic constant magnitude (1.0 mm) of 5000 cycles was applied using a universal testing machine to demonstrate plasticization of the polymer. Loading was carried out in water at 23ºC with eight specimens per group (n = 8). Cycling load (N) and deformation (mm) were measured. RESULTS: Force required to deflect the specimens during the first loading cycle and final loading cycle was statistically significantly different (p < 0.05) with one polyamide based polymer (Valplast) and PMMA based polymers (Acrytone and Acron). The other polyamide based polymer (LucitoneFRS), polyester based polymers (EstheShot and EstheShotBright) and polycarbonate based polymer (ReigningN) did not show significant differences (p > 0.05). None of the materials fractured during the loading test. One polyamide based polymer (Valplast) displayed the highest deformation and PMMA based polymers (Acrytone and Acron) exhibited the second highest deformation among the denture base materials. CONCLUSION: It can be concluded that there were considerable differences in the flexural behavior of denture base polymers. This may contribute to the fatigue resistance of the materials.


Asunto(s)
Materiales Dentales/química , Bases para Dentadura , Plásticos/química , Resinas Acrílicas/química , Análisis del Estrés Dental/instrumentación , Humanos , Ensayo de Materiales , Nylons/química , Docilidad , Cemento de Policarboxilato/química , Poliésteres/química , Tereftalatos Polietilenos/química , Polimerizacion , Polímeros/química , Polimetil Metacrilato/química , Estrés Mecánico , Sulfonas/química , Propiedades de Superficie
12.
Acta Biomater Odontol Scand ; 2(1): 20-24, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28642907

RESUMEN

Objective This study evaluated the flexural strengths of reinforced denture base resins subjected to long-term water immersion. Materials and methods Acrylic denture base resin reinforced with metal wire or glass fiber-reinforced composite (FRC), and without reinforcement were tested. Bar-shaped specimens were fabricated. Half of the specimens were stored in 37 °C distilled water for 50 hours (h), the other half were stored in 37 °C distilled water for 180 days (d) before testing. Ten specimens were fabricated per group for each reinforcement/water immersion period combination. The ultimate flexural strength and flexural strength at the proportional limit of reinforced denture base resin were tested. Results The 180 d bulk specimen possessed significantly lower ultimate flexural strength compared with the 50 h bulk specimen (p < 0.05). The ultimate flexural strength of the 50 h metal, 50 h FRC, 180 d metal and the 180 d FRC reinforcement specimens were not significantly different from each other (p > 0.05). The 180 d bulk specimen had a significantly lower flexural strength at the proportional limit compared to the 50 h bulk specimen. The 180 d reinforced specimens of metal and FRC were not significantly different from each of the 50 h specimens. Conclusion The flexural strengths of a reinforced denture base resin did not change after long-term water immersion.

13.
Acta Biomater Odontol Scand ; 2(1): 31-37, 2016 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28642909

RESUMEN

Objective This study investigated the wear resistance of injection-molded thermoplastic denture base resins using nanoindentation instrument. Materials and methods Six injection-molded thermoplastic denture base resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate [PMMA]) and a PMMA conventional heat-polymerized denture-based polymer control were tested. Elastic modulus, hardness, wear depth, and roughness were calculated using a nanoindentation instrument. Results Elastic modulus and hardness of the injection-molded thermoplastic denture base resins were significantly lower than those of the PMMA conventional heat-polymerized denture-based polymer. Wear depth of polycarbonate and PMMA conventional heat-polymerized denture-based polymer were significantly higher than that of other injection-molded thermoplastic denture base resins. The roughness of injection-molded thermoplastic denture base resins was significantly more than that of PMMA conventional heat-polymerized denture-based polymer after testing. Conclusions Wear resistance of injection-molded thermoplastic denture base was low compared to PMMA conventional heat-polymerized denture-based polymers.

14.
Acta Biomater Odontol Scand ; 1(2-4): 81-85, 2015 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-28642906

RESUMEN

Objective: This study evaluated the reinforcing effect of glass fiber-reinforced composite (FRC) reinforcement on flexural strength at the proportional limit (FS-PL) of a repaired denture base resin. Materials and methods: Repaired denture base resins reinforced with metal and with FRC reinforcement, and that without reinforcement were tested. The ultimate flexural strength, the FS-PL and the elastic modulus of repaired denture base resins were tested. The joint efficiency (times) of the repaired denture base resins on the intact denture base resin was evaluated. Results: The repaired denture base resins reinforced with metal reinforcement and with FRC reinforcement had significantly higher ultimate flexural strength than the repaired denture base resin without reinforcement (p < 0.05) and were not significantly different from each other (p > 0.05). The FS-PL of a repaired denture base resin reinforced with the FRC reinforcement was similar to that with the metal reinforcement (p > 0.05), and these were significantly higher than the FS-PL of a repaired denture base resin without reinforcement (p < 0.05). The elastic modulus of the repaired denture base resin reinforced with the FRC reinforcement was significantly lower than that with metal reinforcement (p < 0.05) and was significantly higher than that without reinforcement (p < 0.05). The joint efficiency of the FRC reinforced specimen was 0.98. Conclusion: The FRC reinforcement had a reinforcing effect on the FS-PL of a repaired denture base resin.

15.
Acta Odontol Scand ; 72(8): 859-65, 2014 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-24850507

RESUMEN

OBJECTIVE: This study investigated the influence of water sorption on certain mechanical properties of injection-molded thermoplastic denture base resins. MATERIALS AND METHODS: Six thermoplastic resins (two polyamides, two polyesters, one polycarbonate, one polymethylmethacrylate) and a polymethylmethacrylate (PMMA) conventional heat-polymerized denture-based polymer, selected as a control, were tested. Specimens of each denture base material were fabricated according to ISO 1567 specifications and were either dry or water-immersed for 30 days (n = 10). The ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of the denture base materials were calculated. RESULTS: Water sorption significantly decreased the ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of one of the polyamides and the PMMAs. It also significantly increased the ultimate flexural strength of the polycarbonate. CONCLUSION: The mechanical properties of some injection-molded thermoplastic denture base resins changed after water sorption.


Asunto(s)
Materiales Dentales/química , Bases para Dentadura , Resinas Sintéticas/química , Agua/química , Absorción Fisicoquímica , Adsorción , Módulo de Elasticidad , Humanos , Inmersión , Ensayo de Materiales , Nylons/química , Docilidad , Cemento de Policarboxilato/química , Poliésteres/química , Polimerizacion , Polimetil Metacrilato/química , Estrés Mecánico , Factores de Tiempo
16.
Acta Odontol Scand ; 72(2): 139-44, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24255964

RESUMEN

OBJECTIVE: This study investigated the properties of injection-molded thermoplastic polyester denture base resins. MATERIALS AND METHODS: Two injection-molded thermoplastic polyester denture base resins (polyethylene terephthalate copolymer and polycycloalkylene terephthalate copolymer) were tested. Specimens of each denture base material were fabricated for flexural properties testing, Charpy impact testing and shear bond testing (n = 10). The flexural strength at the proportional limit, elastic modulus, Charpy impact strength and the shear bond strength of the two denture base materials were estimated. RESULTS: The polycycloalkylene terephthalate copolymer denture base resin had significantly lower flexural strength at the proportional limit, lower elastic modulus, higher impact strength and lower shear bond strength compared to the polyethylene terephthalate copolymer denture base resin. CONCLUSION: The properties of the injection-molded thermoplastic denture base resins composed of polyethylene terephthalate copolymer and polycycloalkylene terephthalate copolymer were different from each other. The polycycloalkylene terephthalate copolymer denture base resin had significantly lower flexural strength at the proportional limit, lower elastic modulus, higher impact strength and lower shear bond strength compared to the polyethylene terephthalate copolymer denture base resin.


Asunto(s)
Resinas Acrílicas , Bases para Dentadura , Poliésteres , Análisis de Varianza
17.
Acta Odontol Scand ; 71(5): 1250-4, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23339746

RESUMEN

OBJECTIVE: This study investigated the shear bond strength of an autopolymerizing repair resin to injection-molded thermoplastic denture base resins. MATERIALS AND METHODS: Four injection-molded thermoplastic resins (two polyamides, a polyethylene terephthalate copolymer and a polycarbonate) were used in this study. The specimens were divided into eight groups according to the type of surface treatment given: (1) no treatment, (2) air abrasion with alumina, (3) dichloromethane, (4) ethyl acetate, (5) 4-META/MMA-TBB resin, (6) alumina and 4-META/MMA-TBB resin, (7) tribochemical silica coating or (8) tribochemical silica coating and 4-META/MMA-TBB resin. Half of the specimens in groups 1, 5, 6 and 8 were thermocycled for 10,000 cycles in water between 5-55°C with a dwell time of 1 min at each temperature. The shear bond strengths were determined. RESULTS: The shear bond strengths to the two polyamides treated with alumina, dichloromethane and ethyl acetate and no treatment were very low. The greatest post-thermocycling bond strengths to polyamides were recorded for the specimens treated with tribochemical silica coating and 4-META/MMA-TBB resin (PA12: 16.4 MPa, PACM12: 17.5 MPa). The greatest post-thermocycling bond strengths to polyethylene terephthalate copolymer and polycarbonate were recorded for the treatment with alumina and 4-META/MMA-TBB resin (22.7 MPa, 20.8 MPa). CONCLUSION: Polyamide was exceedingly difficult to bond to an autopolymerizing repair resin; the shear bond strength improved using tribochemical silica coating followed by the application of 4-META/MMA-TBB resin. Both polyethylene terephthalate copolymer and polycarbonate were originally easy to bond to an autopolymerizing repair resin. However, with 4-META/MMA-TBB resin, the bond was more secure.


Asunto(s)
Dentaduras , Polímeros/química , Resinas Sintéticas , Ensayo de Materiales
18.
Acta Odontol Scand ; 71(3-4): 716-20, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-22900745

RESUMEN

OBJECTIVE: The aim of this study was to investigate the flexural properties of denture base resins subjected to long-term water immersion. MATERIALS AND METHODS: Four denture base resins (one conventional heat-processed, one microwave energy-processed and two pour-type autopolymerizing) were selected for this study. The specimens of each denture base material tested were fabricated according to the manufacturers' instructions (n = 10). The flexural properties of the denture base resins were measured according to ISO 20795-1. The ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of the specimens were evaluated. RESULTS: The ultimate flexural strengths of the heat-processed resin and the two pour-type autopolymerizing resins significantly decreased after 6 months water immersion. The flexural strength at the proportional limit of the heat-processed resin significantly decreased after 6 months water immersion, but the microwave energy-processed denture base resin and two pour-type autopolymerizing resins did not change after 6 months water immersion. The elastic moduli of the heat-processed resin, the microwave energy-processed denture base resin and one pour-type autopolymerizing resin significantly increased after 6 months water immersion. CONCLUSION: The flexural properties of denture base resins significantly changed after long-term water immersion.


Asunto(s)
Dentaduras , Resinas Sintéticas , Agua , Análisis de Varianza , Ensayo de Materiales
19.
Acta Odontol Scand ; 70(4): 297-302, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21793643

RESUMEN

OBJECTIVE: This study investigated the effect of thermal shock on the mechanical properties of injection-molded thermoplastic denture base resins. MATERIALS AND METHODS: Four thermoplastic resins (two polyamides, one polyethylene terephthalate, one polycarbonate) and, as a control, a conventional heat-polymerized polymethyl methacrylate (PMMA), were tested. Specimens of each denture base material were fabricated according to ISO 1567 and were either thermocycled or not thermocycled (n = 10). The flexural strength at the proportional limit (FS-PL), the elastic modulus and the Charpy impact strength of the denture base materials were estimated. RESULTS: Thermocycling significantly decreased the FS-PL of one of the polyamides and the PMMA and it significantly increased the FS-PL of one of the polyamides. In addition, thermocycling significantly decreased the elastic modulus of one of the polyamides and significantly increased the elastic moduli of one of the polyamides, the polyethylene terephthalate, polycarbonate and PMMA. Thermocycling significantly decreased the impact strength of one of the polyamides and the polycarbonate. CONCLUSIONS: The mechanical properties of injection-molded thermoplastic denture base resins changed after themocycling.


Asunto(s)
Análisis del Estrés Dental , Bases para Dentadura , Calor , Resinas Sintéticas , Módulo de Elasticidad , Ensayo de Materiales , Fenómenos Mecánicos , Nylons/química , Docilidad , Cemento de Policarboxilato/química , Tereftalatos Polietilenos/química , Resinas Sintéticas/química
20.
Acta Odontol Scand ; 69(2): 75-9, 2011 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-20873995

RESUMEN

OBJECTIVE: To investigate the mechanical properties of injection-molded thermoplastic denture base resins. MATERIAL AND METHODS: Four injection-molded thermoplastic resins (two polyamides, one polyethylene terephthalate, one polycarbonate) and, as a control, a conventional heat-polymerized polymethyl methacrylate (PMMA), were used in this study. The flexural strength at the proportional limit (FS-PL), the elastic modulus, and the Charpy impact strength of the denture base resins were measured according to International Organization for Standardization (ISO) 1567 and ISO 1567:1999/Amd 1:2003. RESULTS: The descending order of the FS-PL was: conventional PMMA > polyethylene terephthalate, polycarbonate > two polyamides. The descending order of the elastic moduli was: conventional PMMA > polycarbonate > polyethylene terephthalate > two polyamides. The descending order of the Charpy impact strength was: polyamide (Nylon PACM12) > polycarbonate > polyamide (Nylon 12), polyethylene terephthalate > conventional PMMA. CONCLUSIONS: All of the injection-molded thermoplastic resins had significantly lower FS-PL, lower elastic moduli, and higher or similar impact strength compared to the conventional PMMA. The polyamide denture base resins had low FS-PL and low elastic moduli; one of them possessed very high impact strength, and the other had low impact strength. The polyethylene terephthalate denture base resin showed a moderately high FS-PL, moderate elastic modulus, and low impact strength. The polycarbonate denture base resin had a moderately high FS-PL, moderately high elastic modulus, and moderate impact strength.


Asunto(s)
Materiales Dentales/química , Bases para Dentadura , Resinas Sintéticas/química , Resinas Acrílicas/química , Módulo de Elasticidad , Dureza , Humanos , Inyecciones , Ensayo de Materiales , Fenómenos Mecánicos , Nylons/química , Docilidad , Cemento de Policarboxilato/química , Tereftalatos Polietilenos/química , Polímeros/química , Polimetil Metacrilato/química , Sulfonas/química , Propiedades de Superficie
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