RESUMO
OBJECTIVES: The aim of this study was to evaluate the influence of ferule and the post type on the fracture strength and stress distribution in premolars. MATERIALS AND METHODS: Forty human mandibular premolars were decoronated, allocated in four groups, and restored as follows: CPC-NF: cast post-and-core and absence of ferule; CPC-F: cast post-and-core and presence of ferule; FPC-NF: glass-fiber posts and absence of ferule; FPC-F: glass-fiber posts and presence of ferule. The fracture strength (FS) and failure patterns were evaluated. Finite element analysis (FEA) evaluated the stress distribution. RESULTS: FS did not differ between CPCs and FPC either in presence or in absence of ferule. The presence of ferule increased FS with both post types. Mean values of FS for ferule groups were higher than functional or parafunctional loads reported in literature, which was not the case for FPC-NF when compared to parafunctional loads. FEA with a functional load showed slightly higher compressive stresses in dentin in the group CPC-NF, which was much lower than the compressive strength of dentin. Lower percentage of catastrophic failures was observed in nonferule groups irrespective of post type, which was explained by the stress concentration in the cervical root region when FEA with the FS load was simulated. CONCLUSION: Ferule effect was shown to be more important than post type in the analysis. Both posts showed potential to withstand functional loads irrespective of presence of ferule. However, the mean FS was lower than parafunctional loads for FPC in the absence of ferule.
Assuntos
Força Compressiva/fisiologia , Resistência à Flexão/fisiologia , Vidro/química , Fraturas dos Dentes/fisiopatologia , Dente Pré-Molar/fisiopatologia , Resinas Compostas/química , Materiais Dentários/química , Falha de Restauração Dentária , Análise do Estresse Dentário/métodos , Análise de Elementos Finitos , Humanos , Teste de Materiais/métodos , Cimentos de Resina/química , Estresse MecânicoRESUMO
AIM: The aim of this study was to evaluate the fracture resistance of teeth submitted to several internal bleaching protocols using 35% hydrogen peroxide (35HP), 37% carbamide peroxide (37CP), 15% hydrogen peroxide with titanium dioxide nanoparticles (15HPTiO2) photoactivated by LED-laser or sodium perborate (SP). MATERIALS AND METHODS: After endodontic treatment, fifty bovine extracted teeth were divided into five groups (n = 10): G1-unbleached; G2-35HP; G3-37CP; G4-15HPTiO2 photoactivated by LED-laser and G5-SP. In the G2 and G4, the bleaching protocol was applied in 4 sessions, with 7 days intervals between each session. In the G3 and G5, the materials were kept in the pulp teeth for 21 days, but replaced every 7 days. After 21 days, the teeth were subjected to compressive load at a cross head speed of 0.5 mm/min, applied at 135° to the long axis of the root using an eletromechanical testing machine, until teeth fracture. The data were submitted to ANOVA and Tukey tests (α = 5%). RESULTS: The 35HP, 37CP, 15HPTiO2 and SP showed similar fracture resistance teeth reduction (p > 0.05). All bleaching treatments reduced the fracture resistance compared to unbleached teeth (p < 0.05). CONCLUSION: All bleaching protocols reduced the fracture resistance of endodontically-treated teeth, but there were no differences between each other. CLINICAL SIGNIFICANCE: There are several internal bleaching protocols using hydrogen peroxide in different concentrations and activation methods. This study evaluated its effects on fracture resistance in endodontically-treated teeth.
Assuntos
Cavidade Pulpar/efeitos dos fármacos , Clareadores Dentários/uso terapêutico , Clareamento Dental/métodos , Fraturas dos Dentes/fisiopatologia , Animais , Boratos/uso terapêutico , Peróxido de Carbamida , Bovinos , Análise do Estresse Dentário/instrumentação , Peróxido de Hidrogênio/uso terapêutico , Terapia com Luz de Baixa Intensidade , Teste de Materiais , Nanopartículas , Peróxidos/uso terapêutico , Fármacos Fotossensibilizantes/uso terapêutico , Distribuição Aleatória , Tratamento do Canal Radicular/métodos , Estresse Mecânico , Fatores de Tempo , Titânio/uso terapêutico , Ureia/análogos & derivados , Ureia/uso terapêuticoRESUMO
OBJECTIVE: To evaluate the impact of the type of root canal preparation, intraradicular post and mechanical cycling on the fracture strength of roots. MATERIAL AND METHODS: eighty human single rooted teeth were divided into 8 groups according to the instruments used for root canal preparation (manual or rotary instruments), the type of intraradicular post (fiber posts- FRC and cast post and core- CPC) and the use of mechanical cycling (MC) as follows: Manual and FRC; Manual, FRC and MC; Manual and CPC; Manual, CPC and MC; Rotary and FRC; Rotary, FRC and MC; Rotary and CPC; Rotary, CPC and MC. The filling was performed by lateral compactation. All root canals were prepared for a post with a 10 mm length, using the custom #2 bur of the glass fiber post system. For mechanical cycling, the protocol was applied as follows: an angle of incidence of 45°, 37°C, 88 N, 4 Hz, 2 million pulses. All groups were submitted to fracture strength test in a 45° device with 1 mm/ min cross-head speed until failure occurred. RESULTS: The 3-way ANOVA showed that the root canal preparation strategy (p<0.03) and post type (p<0.0001) affected the fracture strength results, while mechanical cycling (p=0.29) did not. CONCLUSION: The root canal preparation strategy only influenced the root fracture strength when restoring with a fiber post and mechanical cycling, so it does not seem to be an important factor in this scenario.
Assuntos
Técnica para Retentor Intrarradicular/instrumentação , Preparo de Canal Radicular/instrumentação , Preparo de Canal Radicular/métodos , Fraturas dos Dentes/etiologia , Raiz Dentária/lesões , Análise de Variância , Resinas Compostas/química , Instrumentos Odontológicos , Análise do Estresse Dentário , Dentina/anatomia & histologia , Humanos , Teste de Materiais , Reprodutibilidade dos Testes , Estresse Mecânico , Propriedades de Superfície , Fraturas dos Dentes/fisiopatologia , Raiz Dentária/anatomia & histologiaRESUMO
PURPOSE: The aim of this study was to evaluate the mode of fracture and resistance of partial ceramic restorations of posterior teeth. MATERIALS AND METHODS: Thirty healthy upper premolars were selected and divided into three groups (n = 10): Group 1- control, healthy unrestored teeth, group 2-teeth restored with ceramic fragments; and group 3-teeth restored with ceramic overlays. The restorations were manufactured with feldspathic ceramic and cemented with RelyX ARC resin cement. After being stored in distilled water for 7 days, the teeth were subjected to axial compression mechanical testing with a universal testing machine. Force was applied to the long axis of the tooth at a speed of 0.5 mm/min until fracture. The data were analyzed with one-way ANOVA and Tukey's test (5%). The mode of fracture was scored according to the degree of involvement of the tooth structure and the type of restoration. RESULTS: A significant difference (p < 0.05) was showed between groups 2 (1155 N) and 3 (846.6 N), but there was no significant difference between group 1 and the other groups (1046 N), More extensive fractures were prevalent in the healthy teeth group (Group 1), which had no occlusal coverage; less severe fractures were found in groups 2 and 3. CONCLUSION: We conclude that teeth restored with ceramic fragments may offer greater resistance to fractures compared to teeth that have overlay restorations.
Assuntos
Cerâmica/química , Porcelana Dentária/química , Planejamento de Prótese Dentária , Falha de Restauração Dentária , Restaurações Intracoronárias , Condicionamento Ácido do Dente/métodos , Silicatos de Alumínio/química , Dente Pré-Molar/fisiopatologia , Bis-Fenol A-Glicidil Metacrilato/química , Força Compressiva , Análise do Estresse Dentário/instrumentação , Humanos , Ácido Fluorídrico/química , Teste de Materiais , Polietilenoglicóis/química , Ácidos Polimetacrílicos/química , Compostos de Potássio/química , Cimentos de Resina/química , Estresse Mecânico , Propriedades de Superfície , Fatores de Tempo , Fraturas dos Dentes/fisiopatologia , Água/químicaRESUMO
AIM: To evaluate the capability to reinforce tooth structure and sealing ability of temporary filling materials in premolars with MOD cavities. The hypothesis is that temporary filling materials can concomitantly prevent microleakage and increase fracture resistance. MATERIALS AND METHODS: Premolars received root canal treatment and MOD cavities. Cavities were restored with non- eugenol cement (CIM), glass ionomer cement (GIC) or light curable composite (BIO). Higid and without restoration were controls. Materials for flexual strength and teeth were tested for microleakage and compressive strength. RESULTS: GIC and Higid presented similar compressive strength, higher than other groups. Bio and GIC presented similar flexural strength higher than BIO. CIM and BIO showed similar micro- leakage lower than GIC. CONCLUSION: The hypothesis was rejected as filling materials tested failed to prevent microleakage and to increase fracture resistance concomitantly. CLINICAL SIGNIFICANCE: GIC may be considered to restore weakened teeth subjected to occlusal loads. BIO and CIM are better choices to microleakage in teeth not subjected to mechanical stresses.
Assuntos
Dente Pré-Molar/patologia , Colagem Dentária , Preparo da Cavidade Dentária/classificação , Cimentos Dentários/química , Restauração Dentária Temporária/métodos , Força Compressiva , Infiltração Dentária/classificação , Cimentos de Ionômeros de Vidro/química , Humanos , Umidade , Teste de Materiais , Maleabilidade , Cimentos de Resina/química , Materiais Restauradores do Canal Radicular/química , Tratamento do Canal Radicular/métodos , Estresse Mecânico , Temperatura , Fatores de Tempo , Fraturas dos Dentes/fisiopatologiaRESUMO
Horizontal root fractures (HRF) usually affect the anterior teeth as a result of trauma, and generally heal spontaneously, depending on the vitality of the pulp. Diagnosis based on clinical findings, sensitivity tests, and radiographic examination is important to determine the presence of a root fracture and to prevent a root fracture from passing unnoticed. Cone-beam computed tomography (CBCT) has been used successfully for diagnosis and prognosis imaging of root fractures and has proved to be superior to other radiographic methods. This study reports two cases of dental trauma caused by a collision and a sports accident. The patients suffered horizontal root fractures in the maxillary left central incisor and in the mandibular left central incisor. The diagnosis of root fracture was confirmed by cone-beam computed tomography (CBCT) images, which also demonstrated spontaneous healing of the fracture line. The repair occurred by interposition of connective tissue in the former case and by interposition of bone and connective tissue in the latter case. The final diagnoses of both cases were based on CBCT images, indicating the importance of a CBCT examination to reach a firm diagnosis and to follow the healing process of root fracture cases, avoiding unnecessary radical endodontic treatment.
Assuntos
Tomografia Computadorizada de Feixe Cônico/métodos , Incisivo/lesões , Fraturas dos Dentes/fisiopatologia , Raiz Dentária/lesões , Acidentes , Adulto , Traumatismos em Atletas/diagnóstico por imagem , Traumatismos em Atletas/fisiopatologia , Tecido Conjuntivo/diagnóstico por imagem , Diagnóstico Precoce , Seguimentos , Humanos , Incisivo/diagnóstico por imagem , Masculino , Planejamento de Assistência ao Paciente , Fraturas dos Dentes/diagnóstico por imagem , Raiz Dentária/diagnóstico por imagem , Cicatrização/fisiologiaRESUMO
Objective: To evaluate the impact of the type of root canal preparation, intraradicular post and mechanical cycling on the fracture strength of roots. Material and Methods: eighty human single rooted teeth were divided into 8 groups according to the instruments used for root canal preparation (manual or rotary instruments), the type of intraradicular post (fiber posts- FRC and cast post and core- CPC) and the use of mechanical cycling (MC) as follows: Manual and FRC; Manual, FRC and MC; Manual and CPC; Manual, CPC and MC; Rotary and FRC; Rotary, FRC and MC; Rotary and CPC; Rotary, CPC and MC. The filling was performed by lateral compactation. All root canals were prepared for a post with a 10 mm length, using the custom #2 bur of the glass fiber post system. For mechanical cycling, the protocol was applied as follows: an angle of incidence of 45°, 37°C, 88 N, 4 Hz, 2 million pulses. All groups were submitted to fracture strength test in a 45° device with 1 mm/ min cross-head speed until failure occurred. Results: The 3-way ANOVA showed that the root canal preparation strategy (p<0.03) and post type (p<0.0001) affected the fracture strength results, while mechanical cycling (p=0.29) did not. Conclusion: The root canal preparation strategy only influenced the root fracture strength when restoring with a fiber post and mechanical cycling, so it does not seem to be an important factor in this scenario. .
Assuntos
Humanos , Técnica para Retentor Intrarradicular/instrumentação , Preparo de Canal Radicular/instrumentação , Preparo de Canal Radicular/métodos , Fraturas dos Dentes/etiologia , Raiz Dentária/lesões , Análise de Variância , Resinas Compostas/química , Instrumentos Odontológicos , Análise do Estresse Dentário , Dentina/anatomia & histologia , Teste de Materiais , Reprodutibilidade dos Testes , Estresse Mecânico , Propriedades de Superfície , Fraturas dos Dentes/fisiopatologia , Raiz Dentária/anatomia & histologiaRESUMO
STATEMENT OF PROBLEM: It is unclear how the amount of remaining coronal dentin and the type of post and core rehabilitation affect the strain, stress distribution, and fracture resistance of endodontically treated teeth. PURPOSE: The purpose of this study was to evaluate the effects of the type of post, type of crown, and the amount of remaining coronal dentin on the biomechanical behavior of endodontically treated teeth. MATERIAL AND METHODS: The investigation was conducted by using 3-dimensional finite element analysis and laboratory tests. Three-dimensional models of a maxillary central incisor were generated: without remaining coronal dentin, with 1.0 mm of remaining coronal dentin, with 2.0 mm of remaining coronal dentin, and restored with a glass-fiber post or a cast post and core in combination with a metal crown or an alumina-reinforced ceramic crown. The results were evaluated by using the von Mises criterion and Maximum Principal Stress. One hundred twenty bovine incisors were selected and divided into 12 treatment groups (n=10). Specimens were loaded at a 135-degree angle to perform strain measurements and were then loaded until fracture. The strain and fracture resistance results were analyzed with 3-way analysis of variance and the Tukey honestly significant difference test (α=.05). RESULTS: The alumina-reinforced ceramic crowns and metal crowns associated with a glass-fiber post showed a homogeneous stress distribution within the root. The cast post and core concentrated higher stresses at the post-dentin interface. Significant differences were found among the mean fracture resistance values for all groups (P<.05). The presence of 2.0 mm of coronal remnants resulted in lower strains and higher fracture resistance for both the metal and ceramic crowns. Roots restored with glass-fiber posts exhibited more favorable fractures. CONCLUSIONS: The presence of 2 mm of remaining coronal dentin improved the mechanical behavior of the endodontically treated maxillary incisors. Teeth restored with glass-fiber posts and composite resin cores showed a homogeneous stress distribution within the root dentin.
Assuntos
Coroas/classificação , Dentina/patologia , Incisivo/fisiopatologia , Técnica para Retentor Intrarradicular/instrumentação , Dente não Vital/reabilitação , Óxido de Alumínio/química , Animais , Fenômenos Biomecânicos , Bovinos , Cerâmica/química , Simulação por Computador , Desenho Assistido por Computador , Ligas Dentárias/química , Planejamento de Prótese Dentária , Cavidade Pulpar/fisiopatologia , Módulo de Elasticidade , Análise de Elementos Finitos , Vidro/química , Humanos , Imageamento Tridimensional/métodos , Incisivo/patologia , Modelos Anatômicos , Modelos Biológicos , Estresse Mecânico , Fraturas dos Dentes/fisiopatologia , Raiz Dentária/fisiopatologia , Dente não Vital/fisiopatologiaRESUMO
STATEMENT OF PROBLEM: Endodontically treated teeth are known to have reduced structural strength. Glass fiber posts may influence fracture resistance and should be evaluated. PURPOSE: The purpose of this study was to evaluate the influence of glass fiber post length on the fracture resistance of endodontically treated teeth. MATERIAL AND METHODS: Forty intact human maxillary canines were selected and divided into 4 groups, the control group consisting of teeth restored with a custom gold cast post and core, with a length of two-thirds of the root. Other groups received prefabricated glass fiber posts in different lengths: group 1/3, removal of one-third of the sealing material (5 mm); group 1/2, removal of one-half of the sealing material (7.5 mm); and group 2/3, removal of two-thirds of the sealing material (10 mm). All the posts were cemented with resin cement, and the specimens with glass fiber posts received a composite resin core. All the specimens were restored with a metal crown and submitted to a compressive load until failure occurred. The results were evaluated by 1-way ANOVA, and the all pairwise multiple comparison procedures (Tukey honestly significantly difference test) (α=.05). RESULTS: The ANOVA showed significant differences among the groups (P<.002). The Tukey test showed that the control group presented significantly higher resistance to static load than the other groups (control group, 634.94 N; group 1/3, 200.01 N; group 1/2, 212.17 N; and group 2/3, 236.08 N). Although teeth restored with a cast post and core supported a higher compressive load, all of them fractured in a catastrophic manner. For teeth restored with glass fiber posts, the failure occurred at the junction between the composite resin core and the root. CONCLUSION: The length of glass fiber posts did not influence fracture load, but cast post and cores that extended two-thirds of the root length had significantly greater fracture resistance than glass fiber posts.
Assuntos
Materiais Dentários/química , Planejamento de Prótese Dentária , Vidro/química , Técnica para Retentor Intrarradicular/instrumentação , Fraturas dos Dentes/fisiopatologia , Dente não Vital/fisiopatologia , Cimentação/métodos , Resinas Compostas/química , Coroas , Dente Canino/fisiopatologia , Ligas Dentárias/química , Falha de Restauração Dentária , Análise do Estresse Dentário/instrumentação , Ligas de Ouro/química , Humanos , Teste de Materiais , Cimentos de Resina/química , Estresse Mecânico , Propriedades de Superfície , Raiz Dentária/lesões , Dente não Vital/terapiaRESUMO
The aims of this study were to evaluate the effect of root canal filling techniques on root fracture resistance and to analyze, by finite element analysis (FEA), the expansion of the endodontic sealer in two different root canal techniques. Thirty single-rooted human teeth were instrumented with rotary files to a standardized working length of 14 mm. The specimens were embedded in acrylic resin using plastic cylinders as molds, and allocated into 3 groups (n=10): G(lateral) - lateral condensation; G(single-cone) - single cone; G(tagger) - Tagger's hybrid technique. The root canals were prepared to a length of 11 mm with the #3 preparation bur of a tapered glass fiber-reinforced composite post system. All roots received glass fiber posts, which were adhesively cemented and a composite resin core was built. All groups were subjected to a fracture strength test (1 mm/min, 45°). Data were analyzed statistically by one-way ANOVA with a significance level of 5%. FEA was performed using two models: one simulated lateral condensation and Tagger's hybrid technique, and the other one simulated the single-cone technique. The second model was designed with an amount of gutta-percha two times smaller and a sealer layer two times thicker than the first model. The results were analyzed using von Mises stress criteria. One-way ANOVA indicated that the root canal filling technique affected the fracture strength (p=0.004). The G(lateral) and G(tagger) produced similar fracture strength values, while G(single-cone) showed the lowest values. The FEA showed that the single-cone model generated higher stress in the root canal walls. Sealer thickness seems to influence the fracture strength of restored endodontically treated teeth.
O objetivo deste estudo foi avaliar o efeito da técnica de obturação na resistência à fratura de raízes e analisar, por meio de análise de elementos finitos (AEF), a expansão do cimento endodôntico em duas diferentes técnicas de obturação. Trinta dentes humanos unirradiculares foram instrumentados com limas rotatórias, com um comprimento de trabalho padronizado (14 mm). Os espécimes foram embutidos em um cilindro plástico com resina acrílica, e distribuídos em 3 grupos (n=10): G(lateral) - condensação lateral; G(cone único) - cone único; G(tagger) - técnica híbrida de Tagger. Os canais radiculares foram preparados num comprimento de 11 mm com a broca de preparo do sistema de pinos de fibra reforçado por compósito. Todas as raízes receberam pinos de fibra de vidro, as quais foram adesivamente cimentadas, e a reconstrução do núcleo foi realizada com resina composta. Todos os grupos foram submetidos ao teste de resistência à fratura (1 mm/min, 45°). Os dados foram submetidos ao teste de análise de variância 1 fator. A AEF foi executada através de dois modelos: um simulou a técnica da condensação lateral e a técnica híbrida de Tagger, e o outro simulou a técnica do cone único. O último foi desenhado com a guta-percha duas vezes menor e com a espessura de cimento duas vezes maior que o primeiro modelo. Os resultados foram analisados usando o critério de tensão Von Mises. A análise de variância a um fator indicou que a técnica de obturação afetou a resistência à fratura (p=0.004). G(lateral) e G(tagger) obtiveram similares valores de resistência à fratura, enquanto G(cone único) apresentou os menores valores. A AEF mostrou que o modelo do cone único gerou um aumento de tensão nas paredes do canal radicular. A espessura do cimento pareceu influenciar a resistência à fratura dos dentes tratados endodonticamente e restaurados.