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1.
Niger J Clin Pract ; 23(8): 1073-1078, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32788484

RESUMO

Aims: The aim of this study was to compare the retention of different luting agents used with implant-supported restorations. Materials and Methods: A total of 90 custom metal frameworks and copings were prepared and divided into six different luting agent groups (n = 15/group): polycarboxylate cement (PC), resin-modified glass-ionomer cement (RMGIC), two self-adhesive resin cements (SARC), copper-ion zinc-phosphate cement (CZPC), and non-eugenol temporary resin cement (TRC). After sandblasting with 50 µm Al2O3, the copings were cemented on frameworks and stored in artificial saliva for 48 h at 37°C and thermocycled between 5-55°C for 37,500 cycles. Samples were subjected to tensile testing by a universal testing machine, and data were statistically analyzed. Results: The differences between the retention values of types of cement were significant (P < 0.05). The maximum retention value was calculated for CZPC (755,12 ± 55 MPa) while the lowest value was for TRC (311,7 ± 61 Mpa). Conclusion: Neither of the tested cement had superiority over another to ensuring retention. The types of cement presented were meant to be a discretionary guide for the clinician in deciding the amount of the desired retention between castings and abutments.


Assuntos
Implantes Dentários , Retenção em Prótese Dentária , Cimentos de Ionômeros de Vidro/química , Cimento de Policarboxilato/química , Cimento de Fosfato de Zinco/química , Cimentação , Cimentos Dentários , Retenção em Prótese Dentária/métodos , Prótese Dentária Fixada por Implante , Análise do Estresse Dentário/instrumentação , Humanos , Teste de Materiais , Cimentos de Resina , Propriedades de Superfície , Óxido de Zinco
2.
Av. odontoestomatol ; 36(2): 89-97, mayo-ago. 2020. ilus, tab, graf
Artigo em Espanhol | IBECS | ID: ibc-194690

RESUMO

INTRODUCCIÓN: La conexión implante-pilar ha sido sugerida como crucial para el éxito a largo plazo de las restauraciónes sobre implantes oseointegración y para prevenir futuras complicaciónes biológicas y mecánicas. El objetivo de este estudio fué evaluar la influencia del test de fatiga cíclica en el comportamiento de las conexiones internas implante-pilar. MÉTODOS: 36 pilares mutiposición de implantes de titanio de conexión interna fueron divididos en 2 grupos: 18 pilares slim o curvos y 10 pilares rectos con diferentes alturas. Los pilares fueron apretados con una llave de torque a 30 Ncm. Una carga cíclica entre 175 N y 100 N fué aplicada con 30º de inclinación axial al sistema de implantes durante 5 millones de ciclos. RESULTADOS: Los tests biomecánicos muestran una fractura de los implantes y de los tornillos de retención a una carga límite de 100 N de los pilares slim curvos y de 130 N en los pilares rectos. La fracturas aparecieron en la zona de unión entre el cuello y el cuerpo del implante y en los tornillos protéscios. No se han encontrado fracturas en los pilares multiposición. CONCLUSIONES: Este estudio indican que los tests de fatiga cíclica son importantes para analizar la respuesta biomecánica de los diferentes pilares en las conexiones implante-pilar de los sistemas de implantes


INTRODUCTION: The connection implant-abutment has been suggested to be crucial for the long-term success of implant restorations and to prevent future biological and mechanic complications. The aim of this study was to evaluate the influence of fatigue cyclic test in the behavior of internal connection implant-abutments. METHODS: Thirty six titanium abutments of internal connection implants were divided in two groups: 18 slim and 18 right multiunit abutments with different length. Abutments were tightened to 30 Ncm with a torque controller. A cyclic load between 175 N and 100 N according to different implant abutments at a 30-degree angle to the long axis was applied to the implants for a 5 million cycles. RESULTS: Biomechanical testing showed implant and screw retention fracture in a limit load of 100 N of slim implant abutments and 130 N of right implant abutments. Fracture cracks were located in the area between neck and body of implants and screw retention. No abutment fractures were found. CONCLUSIONS: This study indicate that fatigue cyclic test are very important to analize the biomechanical behavior of different abutments in connection implant-abutment of implants systems


Assuntos
Implantes Dentários , Projeto do Implante Dentário-Pivô , Instrumentos Odontológicos , Análise do Estresse Dentário/instrumentação , Análise de Falha de Equipamento/métodos , Titânio , Dente Suporte , Estresse Mecânico
3.
Int Orthod ; 17(3): 469-477, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31383599

RESUMO

OBJECTIVE: The aim of this study was to evaluate the effect of intraoral aging and sterilization on the physical properties of rectangular Nickel-Titanium (NiTi), Beta-Titanium and Cooper NiTi (Cu-NiTi) arch wires. METHODS: Three types of preformed 0.018×0.025 inch wires: super elastic NiTi wire, Beta-Titanium wire and Cu-NiTi wire (20 of each type) were divided into 4 groups: as-received (T0), autoclave (T1), intra oral aging after sterilization (T2) and intra oral aging (T3). Specimens in T2 and T3 groups were used in oral environment of 30 participants for 8 weeks. In the next step a length of 30mm was cut from both ends of each arch wire, and 120 straight specimens were achieved and tested by Instron for evaluating their load deflection properties. Data were analysed by means of One-way ANOVA and Tukey's (honestly significant difference) HSD tests. RESULTS: In NiTi wire, all conditions led to a significant decrease in deactivation mean load compared with control in most deflections (P=0.000). In Cu-NiTi wire, all conditions led also to a significant decrease in deactivation mean load compared with the control (P=0.000). In Beta-Titanium wire, sterilization had no significant effect on the load deflection properties; but significant increase was observed in T2 (in all deflections) and T3 (in 1.8-1mm) compared with the control. CONCLUSIONS: After all conditions, NiTi wire in spite of reduction in stiffness presented a mean load which stayed in category of heavy force. The Cu-NiTi wires saw an improvement in light physiologic force. In contrast, the Beta-Titanium stiffness increased after clinical usage, and the force level remained in the range of heavy force.


Assuntos
Ligas Dentárias/química , Teste de Materiais , Níquel/química , Fios Ortodônticos , Esterilização , Titânio/química , Ligas , Análise de Variância , Análise do Estresse Dentário/instrumentação , Temperatura Alta/efeitos adversos , Humanos , Fenômenos Mecânicos , Esterilização/métodos , Estresse Mecânico , Resistência à Tração
4.
Biomed Mater Eng ; 30(3): 279-285, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30988236

RESUMO

The objective of this study was to evaluate the effect of sodium hypochlorite and chlorhexidine solutions and their inactivating agents on the push-out bond strength of mineral trioxide aggregate (MTA). One hundred fifty root slices were prepared and their root canal spaces were enlarged using diamond burs. MTA was prepared and compacted to root canal spaces. The samples were randomly separated to 4 groups that would be immersed into the selected solutions (5.25% sodium hypochlorite (NaOCl), 5.25% NaOCl and sodium thiosulfate, 2% chlorhexidine (CHX), 2% CHX and a mixture of Tween 80 and 0.3% L-alfa-lecithin) and a control group (n = 30). Push-out bond strength of each specimen was tested with universal testing machine. The data was analyzed by one-way analysis of variance and Tukey tests. There were no significant differences between the push-out bond strength values of the irrigation groups and the control group. A significant difference was found between the push-out bond strength values of NaOCl-Sodium thiosulfate and CHX-L-alpha-lecithin groups. Contact with NaOCl and its neutralizing agent with MTA after 10 minutes of setting period increased the push-out bond strength of MTA. On the other hand, any contact with CHX alone or with subsequent application using L-alfa-lecithin should be avoided since that might decrease the push-out bond strength of freshly mixed MTA.


Assuntos
Compostos de Alumínio/química , Compostos de Cálcio/química , Clorexidina/química , Materiais Dentários/química , Óxidos/química , Irrigantes do Canal Radicular/química , Silicatos/química , Hipoclorito de Sódio/química , Análise do Estresse Dentário/instrumentação , Combinação de Medicamentos , Desenho de Equipamento , Humanos , Lecitinas/química , Teste de Materiais/instrumentação , Polissorbatos/química , Irrigação Terapêutica
5.
Biomed Tech (Berl) ; 64(5): 555-562, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-30875315

RESUMO

The aim of this study was to investigate the retention forces of secondary telescopic crowns made of polyetherketoneketone (PEKK) in combination with primary crowns made of four different dental alloys and to determine whether the retention forces change in the course of up to 5000 simulated wear cycles. A total of four groups of telescopic crowns were investigated: group 1: 10 primary crowns made of a gold alloy (NEOCAST®3), group 2: 10 primary crowns made of a non-precious metal alloy (Girobond NB), group 3: 10 primary crowns made of zirconium (Cercon®base) and group 4: 10 primary crowns made from PEKK (Pekkton®ivory). The corresponding secondary crowns were made from PEKK in all the four groups. Each pair was fixed axially in a wear simulator specifically designed for the study. Overall, 10,000 joining and separating cycles were performed for each group. To simulate intraoral conditions, a saliva substitute served as a lubricant. Force transducers were used to record the retention forces and after completing 10,000 cycles, the surface of each primary crown was examined using a scanning electron microscope (SEM). All groups showed an increase in the retention force for the first 2000 cycles which stayed constant for the remaining 8000 cycles. The Pekkton®ivory/Pekkton®ivory and NEOCAST®3/Pekkton®ivory combinations displayed mean retention force values of 16 N after a slight increase in the retention force. The Cercon®base/Pekkton®ivory and Girobond NB/Pekkton®ivory combinations displayed an initially high increase in the retention force and then showed a mean retention force of up to 29 N. All primary crowns displayed surface wear. Zirconium primary crowns showed the least wear compared to PEKK and the gold and non-precious metal alloys.


Assuntos
Análise do Estresse Dentário/instrumentação , Ligas de Ouro/química , Coroas , Ligas Dentárias , Humanos , Zircônio
6.
J Oral Rehabil ; 46(5): 468-474, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30702766

RESUMO

BACKGROUND: Some occlusal detection products are designed for use on dry teeth, but this is not always achieved. Others are suited for dry and wet applications. OBJECTIVE: The objective of this study is to assess the combined effects, on occlusal contact forces, of two previously studied affecting variables-occlusal detection products and saliva. METHODS: We used a full-arch dentiform with three occlusal detection products (an articulating film, an articulation paper and T-Scan) in combination with human (HS) and an artificial saliva. The maxillary arch assembly, weighing ~54 N (the maximum bite force), was lowered onto (occlusion) and lifted off (disclusion) of the mandibular arch through 10 cycles by a mechanical testing machine. The forces and moments acting on the mandibular arch were continuously recorded by a load cell that supported it. RESULTS: The maximum values of Flateral (the in-occlusal plane component of the occlusal contact force) were analysed by occlusion/disclusion separately using one-way ANOVA, with factor for group type to identify the significant effect of salivas on products, effect of products, effect of salivas with products, effect of human saliva. A difference in occlusion and/or in disclusion was considered different. Statistical differences (P < 0.0001) in Flateral were found in: dry product vs product + HS, dry product vs product + artificial saliva (with articulating film and T-Scan) and HS vs product + HS (with articulation paper and T-Scan). CONCLUSION: All products were affected by the salivas, except articulation paper by artificial saliva.


Assuntos
Força de Mordida , Articuladores Dentários , Análise do Estresse Dentário/instrumentação , Saliva/química , Análise de Variância , Fenômenos Biomecânicos , Modelos Dentários , Humanos , Registro da Relação Maxilomandibular/métodos , Reprodutibilidade dos Testes , Estresse Mecânico , Propriedades de Superfície
7.
Am J Orthod Dentofacial Orthop ; 155(1): 98-107, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30591174

RESUMO

INTRODUCTION: Many factors influence the force changes of clear aligners. The purpose of this study was to identify the various factors that influence the force changes generated by polyethylene terephthalate glycol-modified (PET-G) materials. Therefore, a force measurement system based on a flexible thin-film pressure sensor was established. METHODS: A series of clear aligners with 2 material properties and different activations at the maxillary central incisor, maxillary second premolar, and maxillary permanent first molar was designed and fabricated. The first material was conventional PET-G; the second material was modified PET-G with a higher modulus of elasticity and greater abrasion resistance. Several models, including teeth and aligners, were produced. Then, a force change detection device, including a thin-film pressure sensor, a signal acquisition circuit board, and a computer, was applied to measure changes in the forces delivered by the conventional and modified PET-G materials with increased frequencies of appliance removal. Finally, the forces were repeatedly measured to detect the force changes over 48 hours. RESULTS: The forces of both materials decreased similarly over time. These forces also decreased when the aligner removal frequency increased, but the forces decreased differently. The modified PET-G, with a higher modulus of elasticity and greater abrasion resistance, showed a more stable and lower force change than did the conventional PET-G. CONCLUSIONS: The forces delivered by both materials were within the orthodontic force range. Force changes were apparent when the appliance removal frequency increased. Compared with the conventional material, the modified PET-G material showed better stability. Therefore, the modified PET-G is a promising and applicable material with advantages for both orthodontists and patients.


Assuntos
Análise do Estresse Dentário/instrumentação , Aparelhos Ortodônticos Removíveis , Polietilenoglicóis , Análise do Estresse Dentário/métodos , Elasticidade , Humanos , Teste de Materiais , Desenho de Aparelho Ortodôntico , Polietilenotereftalatos , Estresse Mecânico , Fatores de Tempo
8.
J Prosthodont ; 28(2): e666-e674, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29143403

RESUMO

PURPOSE: To evaluate the effect of distal implant inclination on axial and nonaxial retentive forces of different Locator attachments used to retain mandibular overdentures. MATERIALS AND METHODS: Four duplicate mandibular edentulous acrylic models received 2 implants in the canine areas with 0°, 5°, 10°, and 20° distal inclinations. Experimental overdentures were connected to the implants with Locator extra light retention (Le), Locator light retention (Ll), and Locator medium retention (Lm). For the 20° model, extended range Locator extra-light retention (Lee) and Locator medium retention (Lem) were used. Axial and nonaxial (anterior, posterior, lateral) retentive forces were measured initially and after 540 cycles of denture insertion and removal. Three-way mixed ANOVA was used to analyze axial and nonaxial retentive forces RESULTS: After wear simulation, 20° angulation showed the highest axial retention for Le and Ll while 5° showed the highest retention for Lm; 0° and 5° showed the highest anterior and posterior retention for Lm; 20° showed the highest lateral retention for Le and Ll. For all implant inclinations, Lm showed the highest axial and nonaxial retention, and Le and Lee showed the lowest retention for 10° and 20° inclined implants, respectively. CONCLUSIONS: Axial and nonaxial retention of Locator attachments for implant-retained overdentures are significantly affected by the degree of distal implant inclination and the type of nylon inserts. Lm is recommended to retain overdentures when implants have 5° or 10° distal inclination, and Le and Ll are recommended with 20° inclination to maintain high axial and nonaxial retention after wear.


Assuntos
Prótese Dentária Fixada por Implante , Revestimento de Dentadura , Prótese Dentária Fixada por Implante/métodos , Análise do Estresse Dentário/instrumentação , Análise do Estresse Dentário/métodos , Planejamento de Dentadura , Retenção de Dentadura/métodos , Humanos , Técnicas In Vitro , Mandíbula
9.
Biomed Tech (Berl) ; 64(1): 103-110, 2019 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-29420301

RESUMO

Poor stability of a complete denture is a common problem due to bone atrophy of the edentulous ridge. The aim of the present study was to analyze denture stability after receiving implants and to study the biomechanical properties of denture implants and the bone bed using conventional or mini implants. Five models based on computed tomography (CT) data of edentulous patients were created. The overdentures' connection to the implants was assured by means of ball head abutments and rubber rings. In three models, the denture was supported by two to four conventional implants and in two models, the overdenture was supported by three to five mini implants. The dentures were loaded according to the individual biting forces which was clinically measured by means of pressure sheets. After implantation, the biting forces and displacements of overdentures increased in comparison to complete dentures. Displacements and stresses were higher with mini implants than with conventional ones. Stress in the implants was markedly below the yield stress of titanium grade 5 (880 MPa). An increase in the stress in the bone around the implants was noticed as compared to the situation with complete dentures which was below the physiological range of bone loading (<4 MPa).


Assuntos
Implantes Dentários , Análise do Estresse Dentário/instrumentação , Mandíbula/fisiopatologia , Força de Mordida , Análise do Estresse Dentário/métodos , Retenção de Dentadura , Prótese Total , Revestimento de Dentadura , Humanos
10.
Int J Oral Maxillofac Implants ; 33(6): 1279-1286, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30427958

RESUMO

PURPOSE: The aim of this study was to investigate the influence of the abutment material and the connection geometry on deformation and wear at the internal implant-abutment connection area (IAC), using an optical scanner. MATERIALS AND METHODS: Thirty-two internal conical titanium implants, and two types of prefabricated abutments (zirconia or titanium), each (n = 8) with different connection geometries (hexagon or nonhexagon) were prepared. The inner surfaces of the implants were optically scanned before and after loading for 100,000 cycles in a simulated wet environment. The scanned data were superimposed to calculate potential three-dimensional (3D) deviations. Surfaces of the two respective implants in each group were examined using scanning electron microscopy to observe fretting wear patterns. A two-way analysis of variance (ANOVA) was used for the statistical analysis. RESULTS: The 3D deviation (deformation) was detected at the IAC in relation to the loading direction. The average 3D positive deviation and maximum positive and negative deviations at the IAC were significantly higher with zirconia abutments than with titanium abutments, regardless of connection geometries (all P < .05). However, the average 3D negative and standard 3D deviations were similar between the two materials (both P > .05). The effect of connection geometry was not significant (P > .05). After cyclic loading, an irregular wave-pattern furrow was observed on the connection area of the implant with the titanium abutment, whereas a long and straight groove was detected on that with the zirconia abutment. CONCLUSION: Based on this analysis, the deformation and the wear at the IAC could be significantly affected by the material of the prefabricated abutment.


Assuntos
Projeto do Implante Dentário-Pivô , Materiais Dentários , Desgaste de Restauração Dentária , Titânio/química , Zircônio/química , Fenômenos Biomecânicos , Dente Suporte , Análise do Estresse Dentário/instrumentação , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura
11.
Int J Oral Maxillofac Implants ; 33(4): 770­778, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29894547

RESUMO

PURPOSE: Recently, a torque-measuring micromotor that calculates the integral (I) of torque-depth curve at implant insertion was developed. This device was used to investigate the correlation between (I) and mechanical stress in photoelastic resin blocks with the density of D1 bone. MATERIALS AND METHODS: Using the micromotor, 40 implants (3.75 × 12 mm) were placed in 40 D1 blocks that had been prepared in four different ways. Four groups of 10 blocks each were prepared according to tunnel length (12 or 14 mm) and debris removal (yes or no). After insertion, peri-implant mechanical stress and its correlation with (I) were assessed by photoelastic and linear regression analysis, respectively. Analysis of variance (ANOVA) and Kruskal-Wallis tests investigated differences in mechanical stress patterns and dynamic parameters among the groups. RESULTS: (I) significantly correlated with mechanical stress in D1 resin under all conditions, except for 12-mm implant sites still containing debris. The correlation was significant concerning the whole dataset (r = 0.979) and separately for the coronal (r = 0.940), middle (r = 0.964), and apical (r = 0.948) portions of the implants. Peak torque did not correlate significantly with peri-implant mechanical stress. Longer implant sites and debris removal were significantly associated with lower peri-implant mechanical stress. CONCLUSION: (I) provides a reliable measure of mechanical stress in D1 bone during implant placement. Preparation of longer osteotomies and routine removal of all debris might reduce peri-implant bone stress significantly.


Assuntos
Interface Osso-Implante/fisiologia , Implantação Dentária Endo-Óssea , Implantes Dentários , Análise do Estresse Dentário/instrumentação , Estresse Mecânico , Análise de Variância , Planejamento de Prótese Dentária , Humanos , Análise de Regressão , Torque
12.
Niger J Clin Pract ; 21(4): 525-530, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29607869

RESUMO

Purpose: To compare fracture resistance force (FRF) and failure types of crowns milled from resin nanoceramic (Lava Ultimate)-, and modified polymethylmethacrylate (PMMA) (Vita computer-aided design (CAD)-Temp)-, and PMMA (Telio CAD)-based CAD/computer-assisted manufactured (CAM) blocks. Materials and Methods: Three experimental groups of 10 milled crowns were arranged: Group-1 (Lava Ultimate), Group-2 (Vita CAD-Temp), and Group-3 (Telio CAD). Crowns were machined in sizes similar to a primary second molar stainless steel crown (SSC) and stored in water at 37°C for 30 days. The crowns were seated on Cr-Co dies. Their FRFs were measured using a universal test machine until fracture. FRFs and failure types were recorded and statistically analyzed (P < 0.05). Results: There were statistically significant differences among the groups for both FRFs and failure types. The sources of significant differences for FRFs and failure types were Group-3 and Group-1, respectively. Conclusion: Crowns milled from different chemical structural CAD/CAM blocks may be used for restoration of primary molar teeth.


Assuntos
Desenho Assistido por Computador , Coroas , Materiais Dentários/química , Porcelana Dentária/química , Planejamento de Prótese Dentária , Resinas Compostas/química , Falha de Restauração Dentária , Análise do Estresse Dentário/instrumentação , Humanos , Teste de Materiais , Dente Molar , Cimentos de Resina/química
13.
Niger J Clin Pract ; 21(3): 367-374, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29519988

RESUMO

Objectives: The aim of the present study was to evaluate the effects of self-etch and self-adhesive resin cements on the shear bond strength of ceramic core materials bonded to dentin. Materials and Methods: Extracted, caries-free, human central maxillary incisor teeth were selected, and the vestibule surfaces were cut flat to obtain dentin surfaces. Ceramic core materials (IPS e.max Press and Prettau Zirconia) were luted to the dentin surfaces using three self-etch adhesive systems (Duo-Link, Panavia F 2.0, and RelyX Ultimate Clicker) and two self-adhesive resin systems (RelyX U200 Automix and Maxcem Elite). A shear bond strength test was performed using a universal testing machine. Failure modes were observed under a stereomicroscope, and bonding interfaces between the adhesive resin cements and the teeth were evaluated with a scanning electron microscope. Data were analyzed with Student's t-test and one-way analysis of variance followed by Tukey's test (α = 0.05). Results: The type of adhesive resin cement significantly affected the shear bond strengths of ceramic core materials bonded to dentin (P < 0.05). Significant differences were noted between the ceramic core materials when the specimens were luted with self-adhesive resin cements (P < 0.05). The specimens luted with RelyX Ultimate Clicker had the highest shear bond strengths. Conclusion: The self-etch adhesive resin cements exhibited better shear bond strength than the self-adhesive resin cements, except for Panavia cement in the IPS e.max Press group. However, shear bond strengths of the self-adhesive resin cements were dependent on the nature of the ceramic core materials.


Assuntos
Cerâmica , Colagem Dentária , Adesivos Dentinários/química , Cimentos de Resina/química , Condicionamento Ácido do Dente/métodos , Adesivos , Colagem Dentária/métodos , Cimentos Dentários , Análise do Estresse Dentário/instrumentação , Cimentos de Ionômeros de Vidro/química , Humanos , Resistência ao Cisalhamento , Propriedades de Superfície , Zircônio
14.
Dental Press J Orthod ; 23(6): 64-72, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30672987

RESUMO

OBJECTIVE: To assess the short-term effect of two in vitro erosive challenge protocols on the bond strength of metal orthodontic brackets on bovine enamel. METHODS: Sixty bovine incisors were selected and randomly divided into six groups: AS7 (artificial saliva - 7 days, Control Group); CC7 (Coca-Cola™ - 7 days); LJ7 (lime juice - 7 days); AS30 (artificial saliva - 30 days, Control Group); CC30 (Coca-Cola™ - 30 days); LJ30 (lime juice - 30 days). Microhardness testing was performed prior to the erosive challenge to verify the standardization of samples. Immersion was performed 4x/day for five minutes, for either 7 or 30 days. After immersions were concluded, the brackets were bonded and shear bond strength was assessed after 48 hours. The Adhesive Remnant Index (ARI) was also assessed. Data were analyzed by two-way ANOVA, followed by Tukey's post-hoc and Student's t test for paired samples, and the Kruskal-Wallis non-parametric test (α = 5%). RESULTS: The mean and standard deviation of microhardness testing of total samples were 281.89 ± 44.51 KHN. There was no statistically significant difference in shear bond strength for the time factor (7 or 30 days; F5.54= 0.105; p  = 0.901). However, there was a statistically significant difference for the solution factor (F5.54= 6.671; p  = 0.003). These differences occurred among solutions of Saliva x Coca-Cola™ (p  = 0.003) and Coca-Cola™ x Lime Juice (p = 0.029). The assessment of the Adhesive Remnant Index showed no significant difference between groups. CONCLUSIONS: The immersion time used in the erosion protocols did not affect the bond strength of brackets to teeth. Coca-Cola™ induced significantly higher shear bond strength values than lime juice and artificial saliva. However, the short term effects of 7/30 days in this in vitro study may not be extrapolated for in vivo ones. Clinical studies should be conducted, substantiating the laboratory results.


Assuntos
Bebidas/efeitos adversos , Colagem Dentária/métodos , Esmalte Dentário , Braquetes Ortodônticos , Animais , Bovinos , Ligas Dentárias/química , Análise do Estresse Dentário/instrumentação , Sucos de Frutas e Vegetais/efeitos adversos , Dureza , Concentração de Íons de Hidrogênio , Incisivo , Teste de Materiais , Cimentos de Resina/química , Saliva Artificial/química , Resistência ao Cisalhamento , Propriedades de Superfície , Fatores de Tempo , Erosão Dentária/patologia
15.
Int J Oral Maxillofac Implants ; 32(6): 1333-1337, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29140377

RESUMO

PURPOSE: Manufacturers have inserted a prosthetic index, an internal hexagon to guide prosthetic components inside Morse taper implants. However, it is still unclear if this mechanism could decrease the mechanical strength of Morse taper implants. The aim of this study was to evaluate the influence of the prosthetic index inside Morse taper implants on fracture resistance compared with nonindexed implants. MATERIALS AND METHODS: Fifty-seven Morse taper implants, with 11.5-degree angulation of the internal conical portion, were divided into three groups: implants without the prosthetic index and solid Morse taper universal post (group 1), implants with the prosthetic index and solid Morse taper universal post (group 2), and implants and abutments with the prosthetic index (group 3). All groups were modeled for finite element stress analysis (FEA), simulating force application of a perpendicular load to the abutments. Fracture resistance (n = 10) was determined under the same condition. Dynamic loading (n = 9) was also performed. The statistical analysis was performed using one-way analysis of variance (ANOVA), and the Tukey test was applied (α = .05). The metallographic analysis was used to identify the fracture distribution and the microstructure of the titanium alloy. RESULTS: There was no statistically significant difference between the values of all tested groups. According to the FEA, the prosthetic index region was out of stress. The mean fracture resistances and loading test were 353.7 N and 200 N for group 1, 397.3 N and 170 N for group 2, and 372.0 N and 160 N for group 3, respectively. Metallographic analysis showed a macroscopic failure pattern just as demonstrated by FEA. CONCLUSION: The presence of the prosthetic index on Morse taper implants did not decrease its resistance to fracture for the tested implants.


Assuntos
Projeto do Implante Dentário-Pivô/normas , Implantes Dentários , Análise do Estresse Dentário/instrumentação , Titânio/química , Dente Suporte , Implantes Dentários/normas , Planejamento de Prótese Dentária , Análise de Elementos Finitos , Humanos , Teste de Materiais , Fenômenos Mecânicos , Estresse Mecânico
16.
J Dent ; 67: 94-101, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29031995

RESUMO

OBJECTIVE: To compare bonding of dental adhesive to hypomineralized enamel (HE) after pre-treatment with either 5% sodium hypochlorite (NaOCl) solution or papain-based papacarie gel. METHODS: Normal enamel (NE) and HE obtained from hypomineralized first permanent molars were acid-etched with 32% phosphoric acid and randomly allocated into no deproteinization, deproteinization using 5% NaOCl, or deproteinization usping papacarie gel groups. Subsequently, the specimens were bonded, packed with composite resins and subjected to micro-shear bond strength (MSBS) testing and the data analysed using 2-way ANOVA and Tukey tests. Furthermore, specimens from all groups were subjected for qualitative analysis using scanning electron microscope. RESULTS: Two way-ANOVA showed that the factor "enamel substrate" was significant (p<0.001), "enamel pre-treatment" was not significant and interaction of the two factors was significant (p=0.005). HE produced inferior bonding with dental adhesive compared to NE. Enamel pre-treatment with deproteinization agents enhanced bonding to HE. No significant difference in MSBS was evident between the two deproteinization agents (p>0.05). Qualitative analysis of acid-etched moderate HE showed barely visible enamel rods with irregular etching pattern. Following acid etching and deproteinization, Type I and II etching patterns were observed in moderate HE; while a porous enamel surface with more profound etching patterns in severe HE. CONCLUSIONS: Papain-based papacarie could be an alternative deproteinization agent for bonding dental adhesive to HE. CLINICAL SIGNIFICANCE: Papain-based papacarie, a natural deproteinization agent and a proven chemo-mechanical caries removal agent could be an alternative to NaOCl for enhancement of bond durability of adhesive restorations to HE.


Assuntos
Condicionamento Ácido do Dente/métodos , Resinas Compostas/química , Colagem Dentária/métodos , Cimentos Dentários/farmacologia , Proteínas do Esmalte Dentário/efeitos dos fármacos , Esmalte Dentário/efeitos dos fármacos , Adesivos Dentinários/farmacologia , Cimentos Dentários/química , Esmalte Dentário/ultraestrutura , Análise do Estresse Dentário/instrumentação , Adesivos Dentinários/química , Humanos , Teste de Materiais , Dente Molar , Papaína/química , Papaína/farmacologia , Ácidos Fosfóricos/química , Desnaturação Proteica , Cimentos de Resina/química , Resistência ao Cisalhamento , Hipoclorito de Sódio/química , Hipoclorito de Sódio/farmacologia , Propriedades de Superfície
17.
Braz Oral Res ; 31(suppl 1): e62, 2017 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-28902242

RESUMO

Polymerization shrinkage stress of resin-based materials have been related to several unwanted clinical consequences, such as enamel crack propagation, cusp deflection, marginal and internal gaps, and decreased bond strength. Despite the absence of strong evidence relating polymerization shrinkage to secondary caries or fracture of posterior teeth, shrinkage stress has been associated with post-operative sensitivity and marginal stain. The latter is often erroneously used as a criterion for replacement of composite restorations. Therefore, an indirect correlation can emerge between shrinkage stress and the longevity of composite restorations or resin-bonded ceramic restorations. The relationship between shrinkage and stress can be best studied in laboratory experiments and a combination of various methodologies. The objective of this review article is to discuss the concept and consequences of polymerization shrinkage and shrinkage stress of composite resins and resin cements. Literature relating to polymerization shrinkage and shrinkage stress generation, research methodologies, and contributing factors are selected and reviewed. Clinical techniques that could reduce shrinkage stress and new developments on low-shrink dental materials are also discussed.


Assuntos
Resinas Compostas/química , Análise do Estresse Dentário/métodos , Polimerização , Cimentos de Resina/química , Luzes de Cura Dentária , Análise do Estresse Dentário/instrumentação , Teste de Materiais
18.
Braz. oral res. (Online) ; 31(supl.1): e62, Aug. 2017. graf
Artigo em Inglês | LILACS | ID: biblio-889457

RESUMO

Abstract Polymerization shrinkage stress of resin-based materials have been related to several unwanted clinical consequences, such as enamel crack propagation, cusp deflection, marginal and internal gaps, and decreased bond strength. Despite the absence of strong evidence relating polymerization shrinkage to secondary caries or fracture of posterior teeth, shrinkage stress has been associated with post-operative sensitivity and marginal stain. The latter is often erroneously used as a criterion for replacement of composite restorations. Therefore, an indirect correlation can emerge between shrinkage stress and the longevity of composite restorations or resin-bonded ceramic restorations. The relationship between shrinkage and stress can be best studied in laboratory experiments and a combination of various methodologies. The objective of this review article is to discuss the concept and consequences of polymerization shrinkage and shrinkage stress of composite resins and resin cements. Literature relating to polymerization shrinkage and shrinkage stress generation, research methodologies, and contributing factors are selected and reviewed. Clinical techniques that could reduce shrinkage stress and new developments on low-shrink dental materials are also discussed.


Assuntos
Resinas Compostas/química , Análise do Estresse Dentário/métodos , Polimerização , Cimentos de Resina/química , Luzes de Cura Dentária , Análise do Estresse Dentário/instrumentação , Teste de Materiais
19.
J Oral Rehabil ; 44(10): 791-799, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28681442

RESUMO

Studies have explored occlusal marking interpretation, repeatability and accuracy. But, when an occlusion detection product is interposed between teeth, direct tooth-tooth occlusal contact relationships are replaced by tooth-material-tooth structures. Thus, the marks cannot reflect the original contacts. This has been shown for single tooth pair contacts. The purpose of this laboratory study was to similarly examine full dentitions. A dentiform was set into Class I centric occlusion with the mandible supported by a load cell. The maxillary arch was guided by precision slides. As the weighted (~52 N) upper assembly was lowered onto and raised off the mandibular arch, the loads on the mandible were measured. With and without (control) occlusal marking material, the steps were as follows: (cleaning - control 1 - material 1) … (cleaning - control 6 - material 6). The six materials were as follows: Accufilm I and II, Rudischhauser Thick and Thin, Hanel Articulating Silk and T-Scan. Then, the six sets of (cleaning - control - material) measurements were repeated with the mandibular assembly shifted, in turn, by 0·1 mm in the Anterior, Posterior, Right and Left directions. The five (Centric and four 0·1 mm shifted) occlusal relationships produced grossly different tooth-tooth (control) load profiles. And, in general, these controls were affected, in different ways, by the marking products. Among the five conventional products, the Rudischhausers fared the worst and the electronic T-Scan was an extreme outlier. Thus, in general, popular occlusal detection products alter the occlusal contact forces, and therefore, their markings cannot characterise the actual occlusion.


Assuntos
Modelos Dentários , Oclusão Dentária , Análise do Estresse Dentário/instrumentação , Força de Mordida , Articuladores Dentários , Dentição , Humanos , Registro da Relação Maxilomandibular/métodos , Reprodutibilidade dos Testes
20.
Dent Mater J ; 36(6): 731-739, 2017 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-28652553

RESUMO

The purpose was to describe a novel simple experimental model of injured teeth for developing dental trauma splints (DTS), and to test various splints by combining use of this model and the Periotest® device. Rubber O-rings and spring washers were used to simulate and modify injured tooth mobility. Splinting effects were assessed among three kinds of DTS, including a composite splint and two wire-composite splints (1: rectangular orthodontic wire 0.533×0.635 mm, 2: cobalt-chromium alloy wire Φ0.9 mm). The Periotest values were measured three times for each tooth before and after splint insertion. The splinting effect was defined as the change in tooth mobility. Splinting effects significantly increased in the order wire-composite splint 1

Assuntos
Planejamento de Prótese Dentária , Contenções Periodontais , Traumatismos Dentários/terapia , Ligas de Cromo , Modelos Dentários , Análise do Estresse Dentário/instrumentação , Humanos , Modelos Teóricos , Fios Ortodônticos , Maleabilidade , Reprodutibilidade dos Testes , Mobilidade Dentária/prevenção & controle
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