RESUMO
OBJECTIVE: To evaluate the effect of the labiolingual diameter and construction of an endodontically treated (ET) anterior tooth with crown restoration on stress distribution and biomechanical safety under occlusal loading. METHODOLOGY: Three-dimensional finite element models were generated for maxillary central incisors with all-ceramic crown restorations. The labiolingual diameters of the tooth, defined as the horizontal distance between the protrusion of the labial and lingual surfaces, were changed as follows: (D1) 6.85 mm, (D2) 6.35 mm, and (D3) 5.85 mm. The model was constructed as follows: (S0) vital pulp tooth; (S1) ET tooth; (S2) ET tooth with a 2 mm ferrule, restored with a fiber post and composite resin core; (S3) ET tooth without a ferrule, restored with a fiber post and composite resin core. A total of 12 models were developed. In total, two force loads (100 N) were applied to the crown's incisal edge and palatal surface at a 45° oblique angle to the longitudinal axis of the teeth. The Von Mises stress distribution and maximum stress of the models were analyzed. RESULTS: Regardless of the loading location, stress concentration and maximum stress (34.07~66.78MPa) in all models occurred in the labial cervical 1/3 of each root. Both labiolingual diameter and construction influenced the maximum stress of the residual tooth tissue, with the impact of the labiolingual diameter being greater. A reduction in labiolingual diameter led to increased maximum stress throughout the tooth. The ferrule reduced the maximum stress of the core of S2 models (7.15~10.69 MPa), which is lower compared with that of S3 models (19.45~43.67 MPa). CONCLUSION: The labiolingual diameter exerts a greater impact on the biomechanical characteristics of ET anterior teeth with crown restoration, surpassing the influence of the construction. The ferrule can reduce the maximum stress of the core and maintain the uniformity of stress distribution.
Assuntos
Resinas Compostas , Coroas , Análise do Estresse Dentário , Análise de Elementos Finitos , Incisivo , Dente não Vital , Dente não Vital/fisiopatologia , Humanos , Fenômenos Biomecânicos , Incisivo/anatomia & histologia , Incisivo/fisiologia , Resinas Compostas/química , Análise do Estresse Dentário/métodos , Técnica para Retentor Intrarradicular , Reprodutibilidade dos Testes , Estresse Mecânico , Valores de Referência , Força de Mordida , Imageamento Tridimensional/métodos , Planejamento de Prótese Dentária , Teste de Materiais , Coroa do Dente/anatomia & histologia , Coroa do Dente/fisiologiaRESUMO
BACKGROUND: Evaluate the fracture resistance of endodontically treated teeth after cervical preflaring and root canal preparation and to assess the volume of the root canal and the amount of remaining root dentin before and after cervical preflaring. METHODS: Forty-four mandibular incisors were selected using micro-CT scanning and distributed into 4 groups (n = 11) according to the instrument used for cervical preflaring: control group - no cervical preflaring; Gates Glidden - burs size #2 and #3; WXN - 25.07 Navigator instrument; and Easy - 25.08 ProDesign S instrument. Coronal opening was performed, and the canals were prepared with Wave One Gold Primary and filled with an epoxy-resin based sealer and gutta-percha cones. Micro-CT scans were performed before and after root canal instrumentation. All images were reconstructed and assessed for the thickness of mesial and distal root dentin at 3 mm and 5 mm from the cement -enamel junction and for the volume of cervical portion of the canal after preparation. Fracture resistance test was performed applying compressive loads at a crosshead speed of 0.5 mm/min, applied on the palatal aspect of specimens at 135° along the long axis of the tooth. The data were analyzed using ANOVA and Tukey's test (P = .05). RESULTS: Cervical preflaring and canal preparation reduced the dentin thickness (P < .05) and increased the canal volume (P < .05) in all groups at 3 mm an 5 mm. Cervical preflaring with Gates Gliden burs reduced the fracture resistance of endodontically treated teeth (P < .05). CONCLUSIONS: All instruments reduced the dentin thickness and increased the canal volume in the cervical at 3 mm and 5 mm. Gates Glidden reduced fracture resistance of mandibular incisors submitted to cervical preflaring, whereas NiTi instruments did not. CLINICAL RELEVANCE: Cervical preflaring assumes particular importance previously to the root canal preparation because it minimizes the occurrence of operative accidents, and permits more accurate determination of working length and the apical diameter.
Assuntos
Cavidade Pulpar/patologia , Guta-Percha/uso terapêutico , Materiais Restauradores do Canal Radicular/uso terapêutico , Preparo de Canal Radicular/instrumentação , Dente não Vital/fisiopatologia , Resinas Epóxi/uso terapêutico , Humanos , Preparo de Canal Radicular/métodos , Fraturas dos Dentes , Dente não Vital/diagnóstico por imagemRESUMO
This study evaluated the stress distribution in endodontically treated teeth, weakened (W) or not weakened (NW), restored with different materials of prosthetic crown using 3D-FEA. Models of a maxillary canine were constructed based on micro-CT images and divided into the groups: G1 (control) - sound tooth; G2 to G7 - endodontically treated teeth restored with glass fiber post (GFP); which G2 to G4 simulated NW root and G5 to G7 simulated W root. For crown material the teeth were restored with: G2 and G5: metallic coping and ceramic veneering, G3 and G6: zirconia coping and ceramic veneering, G4 and G7: alumina coping and ceramic veneering. Load of 180 N was applied at the incisal third of lingual surface at 45º. Models were supported by the periodontal ligament (x=y=z=0). The von Mises stress (VMS) values were calculated. The W teeth presented higher VMS at coping when compared to NW teeth and group G1 showed lower VMS value. For crown material, for both W or NW teeth, increasing VMS was found at metallic, zirconia and alumina coping, respectively. Metallic coping showed a better performance despite its unfavorable esthetics, suggesting as an appropriate material for prosthetic restoration of endodontically treated teeth.
Assuntos
Coroas , Análise do Estresse Dentário , Teste de Materiais , Dente não Vital/fisiopatologia , Análise de Elementos Finitos , Humanos , Dente não Vital/terapiaRESUMO
Abstract This study evaluated the stress distribution in endodontically treated teeth, weakened (W) or not weakened (NW), restored with different materials of prosthetic crown using 3D-FEA. Models of a maxillary canine were constructed based on micro-CT images and divided into the groups: G1 (control) - sound tooth; G2 to G7 - endodontically treated teeth restored with glass fiber post (GFP); which G2 to G4 simulated NW root and G5 to G7 simulated W root. For crown material the teeth were restored with: G2 and G5: metallic coping and ceramic veneering, G3 and G6: zirconia coping and ceramic veneering, G4 and G7: alumina coping and ceramic veneering. Load of 180 N was applied at the incisal third of lingual surface at 45º. Models were supported by the periodontal ligament (x=y=z=0). The von Mises stress (VMS) values were calculated. The W teeth presented higher VMS at coping when compared to NW teeth and group G1 showed lower VMS value. For crown material, for both W or NW teeth, increasing VMS was found at metallic, zirconia and alumina coping, respectively. Metallic coping showed a better performance despite its unfavorable esthetics, suggesting as an appropriate material for prosthetic restoration of endodontically treated teeth.
Resumo Este estudo avaliou a distribuição de tensão em dentes tratados endodonticamente, fragilizados (F) ou não fragilizados (NF), restaurados com diferentes materiais para a coroa protética utilizando 3D-FEA. Modelos de um canino maxilar foram construídos baseados em imagens de micro-CT e divididos em grupos: G1 (controle) - dente hígido; G2 a G7 - dentes tratados endodonticamente com pino de fibra de vidro (PFV), sendo que G2 a G4 simularam raízes NF e G5 a G7 simularam raízes F. Para o material das coroas os dentes foram restaurados com: G2 e G5: coping metálico e revestimento cerâmico, G3 e G6: coping de zirconia e revestimento cerâmico, G4 e G7: coping de alumina e revestimento cerâmico. Carregamento de 180 N foi aplicado na superfície lingual em seu terço incisal com 45 graus de inclinação. Os modelos foram suportados pelo ligamento periodontal (x=y=z=0). Os valores da tensão de von Mises (VMS) foram calculados. Os dentes F apresentaram maiores valores VMS para o coping quando comparados aos dentes NF, sendo que o G1 apresentou menores valores VMS. Para o material das coroas, ambos F ou NF aumentaram VMS no coping metálico, zirconia e alumina, respectivamente. Copings metálicos apresentaram melhor comportamento mecânico apesar de não favorecerem a estética, o que sugere ser um material apropriado para a restauração de dentes tratados endodonticamente.
Assuntos
Humanos , Coroas , Análise do Estresse Dentário , Dente não Vital/fisiopatologia , Análise de Elementos Finitos , Dente não Vital/terapiaRESUMO
Tissue repair is an essential process that reestablishes tissue integrity and regular function. Nevertheless, different therapeutic factors and clinical conditions may interfere in this process of periapical healing. This review aims to discuss the important therapeutic factors associated with the clinical protocol used during root canal treatment and to highlight the systemic conditions associated with the periapical healing process of endodontically treated teeth. The antibacterial strategies indicated in the conventional treatment of an inflamed and infected pulp and the modulation of the host's immune response may assist in tissue repair, if wound healing has been hindered by infection. Systemic conditions, such as diabetes mellitus and hypertension, can also inhibit wound healing. The success of root canal treatment is affected by the correct choice of clinical protocol. These factors are dependent on the sanitization process (instrumentation, irrigant solution, irrigating strategies, and intracanal dressing), the apical limit of the root canal preparation and obturation, and the quality of the sealer. The challenges affecting the healing process of endodontically treated teeth include control of the inflammation of pulp or infectious processes and simultaneous neutralization of unpredictable provocations to the periapical tissue. Along with these factors, one must understand the local and general clinical conditions (systemic health of the patient) that affect the outcome of root canal treatment prediction.
Assuntos
Tecido Periapical/fisiopatologia , Tratamento do Canal Radicular/métodos , Dente não Vital/fisiopatologia , Dente não Vital/terapia , Cicatrização/fisiologia , Cimentos Ósseos/uso terapêutico , Hidróxido de Cálcio/uso terapêutico , Humanos , Periodontite Periapical/terapia , Materiais Restauradores do Canal Radicular/uso terapêutico , Irrigantes do Canal Radicular/uso terapêutico , Resultado do TratamentoRESUMO
Abstract Tissue repair is an essential process that reestablishes tissue integrity and regular function. Nevertheless, different therapeutic factors and clinical conditions may interfere in this process of periapical healing. This review aims to discuss the important therapeutic factors associated with the clinical protocol used during root canal treatment and to highlight the systemic conditions associated with the periapical healing process of endodontically treated teeth. The antibacterial strategies indicated in the conventional treatment of an inflamed and infected pulp and the modulation of the host's immune response may assist in tissue repair, if wound healing has been hindered by infection. Systemic conditions, such as diabetes mellitus and hypertension, can also inhibit wound healing. The success of root canal treatment is affected by the correct choice of clinical protocol. These factors are dependent on the sanitization process (instrumentation, irrigant solution, irrigating strategies, and intracanal dressing), the apical limit of the root canal preparation and obturation, and the quality of the sealer. The challenges affecting the healing process of endodontically treated teeth include control of the inflammation of pulp or infectious processes and simultaneous neutralization of unpredictable provocations to the periapical tissue. Along with these factors, one must understand the local and general clinical conditions (systemic health of the patient) that affect the outcome of root canal treatment prediction.
Assuntos
Humanos , Tecido Periapical/fisiopatologia , Tratamento do Canal Radicular/métodos , Cicatrização/fisiologia , Dente não Vital/fisiopatologia , Dente não Vital/terapia , Periodontite Periapical/terapia , Materiais Restauradores do Canal Radicular/uso terapêutico , Irrigantes do Canal Radicular/uso terapêutico , Cimentos Ósseos/uso terapêutico , Hidróxido de Cálcio/uso terapêutico , Resultado do TratamentoRESUMO
INTRODUCTION: In order to understand the mechanical behavior of a weakened incisor, this study aimed to evaluate the stress distribution caused by different alveolar bone heights and cement layer thickness. METHODS: A finite element analysis was conducted for this investigation. An intact maxillary central incisor was initially modeled, and the bone of the models was modified in order to simulate 4 levels of bone height: BL0 (no bone loss), BL1 (1/3 bone loss), BL2 (1/2 bone loss), and BL3 (2/3 bone loss). These teeth models were remodeled with a fiber post at 2 different cement thicknesses and restored with a ceramic crown; "A" refers to the well-adapted fiber post (0.3 mm) and "B" to the nonadapted fiber post (1 mm), resulting in 12 models. RelyX ARC (3M ESPE, St Paul, MN) cement was simulated for the cementation of the crowns and fiber posts for all groups. Numeric models received a load of 100 N on the lingual surface. All materials and structures were considered linear elastic, homogeneous, and isotropic. Numeric models were plotted and meshed with isoparametric elements, and results were expressed in maximum principal stress. RESULTS: For fiberglass posts, cement, and dentin, the highest stress concentration occurred in the groups with increased bone loss. For cortical bone, the highest values were for the groups with 1/3 bone loss. A greater thickness of cement layer concentrates more stress. CONCLUSIONS: More bone loss and greater CLT were the influential factors in concentrating the stress.
Assuntos
Perda do Osso Alveolar/cirurgia , Cimentos Dentários/uso terapêutico , Incisivo/cirurgia , Dente não Vital/fisiopatologia , Perda do Osso Alveolar/fisiopatologia , Fenômenos Biomecânicos , Força Compressiva , Cimentos Dentários/efeitos adversos , Análise do Estresse Dentário , Análise de Elementos Finitos , Humanos , Imageamento Tridimensional , Incisivo/fisiopatologia , Maxila , Resistência à TraçãoRESUMO
OBJECTIVES: To evaluate the influence of restorative materials used on the rehabilitation of MOD cavities and loading type, on biomechanical behavior of wedge-shaped (WS) lesions in endodontically treated maxillary premolars. The investigation was conducted by 3D finite element analysis (FEA) and strain gauge test. MATERIALS AND METHODS: Six models were generated, with MOD cavities and endodontic treatment: A (MOD amalgam restoration), R (MOD composite restoration), AL (A + cervical lesion (L)), RL, ALR (A + cervical lesion restored with composite (LR)), and RLR. Each model underwent two compressive loading (100N): axial and oblique-45° angle to the long axis on the buccal cusp. The models were analyzed by von Mises criteria. For strain gauge test, 14 standardized maxillary premolars were treated according to the groups described for FEA. Two strain gauges were bonded on each sample submitted to compressive loading in a mechanical testing machine. RESULTS: A presented higher stress concentration and strain values than R. Oblique loading promoted highest stress concentration and strain rates for all groups. ALR and RLR presented similar stress-strain distribution pattern when compared to A and R. CONCLUSION: The interaction between MOD cavity restored with amalgam and oblique loading propitiated the highest stress concentration and strain values on cervical region and WS lesion. CLINICAL RELEVANCE: The MOD cavity restored with composite resin is a better option than amalgam to improve the biomechanical behavior of wedge-shaped lesion, avoiding dental failure. In addition, the occlusal interferences must be removed, allowing homogeneous contact distribution and preventing WS lesion progression.
Assuntos
Dente Pré-Molar/fisiopatologia , Resinas Compostas/química , Amálgama Dentário/química , Preparo da Cavidade Dentária/métodos , Materiais Dentários/química , Falha de Restauração Dentária , Restauração Dentária Permanente/métodos , Dente não Vital/fisiopatologia , Fenômenos Biomecânicos , Bis-Fenol A-Glicidil Metacrilato/química , Análise do Estresse Dentário , Módulo de Elasticidade , Análise de Elementos Finitos , Guta-Percha/química , Estresse MecânicoRESUMO
Durante muchos años se han utilizado los postes colados, considerados como un estándar en la odontología protésica, pero presentan limitantes técnicas y mecánicas, ya que exhiben altos módulos de elasticidad y, por lo mismo, imposibilitan la capacidad de disipar las fuerzas con efectividad, lo que significa concentrar tensiones dentro del conducto radicular. Literatura basada en evidencia científica describe a los postes de fibra de vidrio con módulos de elasticidad semejantes o próximos a la dentina, presentando propiedades anisotrópicas, en comparación con los postes tradicionales, que presentan propiedades isotrópicas. Se propone un concepto restaurador que involucra el poste, el cemento y la dentina, constituyendo un complejo homogéneo denominado ®monobloque¼ que permite un mejor comportamiento mecánico benéfico para el remanente dentario
For many years now, cast posts have been regarded as standard in prosthetics despite the technical and mechanical limitations caused by their high moduli of elasticity, which prevent the forces involved from being effectively dissipated and, therefore, concentrate stress within the root canal. Scientifi c evidence-based literature describes fi berglass posts with moduli of elasticity similar to or approaching that of dentin as having anisotropic properties, as opposed to the isotropic properties of traditional posts. We propose a restorative approach that involves the post, the cement, and the dentin, forming a homogeneous complex known as a ®monobloc¼ that enables enhanced mechanical behavior that benefits the remaining tooth structure.
Assuntos
Humanos , Fenômenos Biomecânicos , Dentina/fisiologia , Restauração Dentária Permanente/tendências , Técnica para Retentor Intrarradicular/tendências , Vidro/química , Cemento Dentário , Dente não Vital/fisiopatologia , Módulo de Elasticidade , Materiais Biocompatíveis/classificação , Resistência à TraçãoRESUMO
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.