Influence of modification in core building procedure on fracture strength and failure patterns of premolars restored with fiber post and composite core

PURPOSE: The influence of the modified process in the fiber-reinforced post and resin core foundation treatment on the fracture resistance and failure pattern of premolar was tested in this study. MATERIALS AND METHODS: Thirty-six human mandibular premolars were divided into 4 groups (n = 9). In group DCT, the quartz fibre post (D.T. Light-post) was cemented with resin cement (DUO-LINK) and a core foundation was formed with composite resin (LIGHT-CORE). In group DMO and DMT, resin cement (DUO-LINK) was used for post (D.T. Light-post) cementation and core foundation; in group DMO, these procedures were performed simultaneously in one step, while DMT group was accomplished in separated two steps. In group LCT, the glass fiber post (LuxaPost) cementation and core foundation was accomplished with composite resin (LuxaCore-Dual) in separated procedures. Tooth were prepared with 2 mm ferrule and restored with nickel-chromium crowns. A static loading test was carried out and loads were applied to the buccal surface of the buccal cusp at a 45 degree inclination to the long axis of the tooth until failure occurred. The data were analyzed with MANOVA (alpha = .05). The failure pattern was observed and classified as either favorable (allowing repair) or unfavorable (not allowing repair). RESULTS: The mean fracture strength was highest in group DCT followed in descending order by groups DMO, DMT, and LCT. However, there were no significant differences in fracture strength between the groups. A higher prevalence of favorable fractures was detected in group DMT but there were no significant differences between the groups. CONCLUSION: The change of post or core foundation method does not appear to influence the fracture strength and failure patterns.

Influence of modification in core building procedure on fracture strength and failure patterns of premolars restored with fiber post and composite core

PURPOSE: The influence of the modified process in the fiber-reinforced post and resin core foundation treatment on the fracture resistance and failure pattern of premolar was tested in this study. MATERIALS AND METHODS: Thirty-six human mandibular premolars were divided into 4 groups (n = 9). In group DCT, the quartz fibre post (D.T. Light-post) was cemented with resin cement (DUO-LINK) and a core foundation was formed with composite resin (LIGHT-CORE). In group DMO and DMT, resin cement (DUO-LINK) was used for post (D.T. Light-post) cementation and core foundation; in group DMO, these procedures were performed simultaneously in one step, while DMT group was accomplished in separated two steps. In group LCT, the glass fiber post (LuxaPost) cementation and core foundation was accomplished with composite resin (LuxaCore-Dual) in separated procedures. Tooth were prepared with 2 mm ferrule and restored with nickel-chromium crowns. A static loading test was carried out and loads were applied to the buccal surface of the buccal cusp at a 45 degree inclination to the long axis of the tooth until failure occurred. The data were analyzed with MANOVA (alpha = .05). The failure pattern was observed and classified as either favorable (allowing repair) or unfavorable (not allowing repair). RESULTS: The mean fracture strength was highest in group DCT followed in descending order by groups DMO, DMT, and LCT. However, there were no significant differences in fracture strength between the groups. A higher prevalence of favorable fractures was detected in group DMT but there were no significant differences between the groups. CONCLUSION: The change of post or core foundation method does not appear to influence the fracture strength and failure patterns.

Evaluation of different post systems: finite element method / Evaluación de diferentes sistemas de postes: método de elementos finitos

The aim of this study was to analyse the stress distribution in maxillary canines restored with different post systems and definitive crowns. The models of restored teeth with glass fiber, quartz fiber, titanium posts and crownswere developed with the Finite Element Method (FEM) in order to analyse their stress distribution when subjected to external compressive loads. Von Mises stress distribution values, which are considered potential fracture indicator, showed that natural tooth and glass fiber post-restored tooth, under a load of 550 N, presented similar stress values. The behaviour of a glass fiber post-restored tooth is similar to that of a natural tooth, since it produces an appropriate stress distribution, and inthis investigation, they have the best biomechanical performance.

El próposito de este estudio fue analizar la distribución de tensiones en caninos superiores restaurados con diferentes sistemas de postes y coronas definitivas. Los modelos de dientes restaurados con postes defibra de vidrio, fibra de cuarzo y titanio y coronas fueron desarrollados con el Método de Elementos Finitos (FEM) para analizar la distribución de tensiones cuando fueron sometidos a cargas compresivas externas. Valores de distribución de stress de Von Mises, que fueron considerados como potenciales indicadores de fracturas, mostraron que los dientes naturales, y los dientes resturados con postes de fibra de vidrio, bajo una carga compresiva de 550N, presentaron valores semejantes. El comportamiento de los dientes restaurados con postes de fibra de vidrio fue similar al de los dientes naturales, mostrando una homogénea y más uniforme distribución del stress, y en esta investigación, presentaron una mejor performance biomecánica.

In vitro evaluation of the effect of different diameters of quartz fiber posts on fracture resistance of dental roots / Avaliação in vitro do efeito de diferentes diâmetros de pinos de fibras de quartzo na resistência à fratura de raízes dentais

OBJECTIVES: One of the controversial factors in fracture resistance of endodontically treated teeth that are reconstructed with fiber posts is the diameter of these posts. The aim of this study is to evaluate the effect of three different sizes of quartz fiber post (#0.5- #2 - #3) on fracture resistance of dental root. MATERIAL AND METHOD: In this in vitro study, 30 mandibular premolars were selected, sectioned from CEJ, endodontically treated and randomly assigned to three groups (n=10). Post spaces were prepared and quartz fiber posts) D.T. Light-Post™ (with three different sizes (#0.5-#2 - #3) were seated respectively in three groups. All posts were cemented with Panavia F 2.0 dual cure resin bonding and cement. Composite resin cores were built up using a preformed polyester matrix. Specimens were embedded in acrylic resin blocks with a layer of elastic polyether Impergum around roots as PDL. A compressive load at a crosshead speed of 1mm/min was applied axially to the central fossa of each specimen using a Universal Testing Machine, until the occurrence of root fracture. Data were analyzed using one-way analysis of variance. RESULTS: There was no significant statistical difference in fracture resistance among three groups (P>0.05). Mean fracture load was 1010±250.95 N for group A with post #0.5 and 934.4± 295.18 N for group B with post #2 and ±1001301.42 N forgroup C with post #3. CONCLUSIONS: According to the findings, larger sizes of fiber posts do not decrease the fracture resistance of the root structure. Larger diameters have higher fracture resistance and furthermore by increasing the bonding area between post and root canal wall and core material, they can improve the unity within root structure and provide more stability for core material. Unlikelarger sizes of metal posts, fiber posts with larger diameters adhere to the root structure more efficiently. As a result, they will not reduce the fracture resistance of root...

OBJETIVOS: Fator controverso na resistência à fratura de dentes endodonticamente tratados, reconstruídos com pinos de fibra, é o diâmetro destes pinos. O objetivo deste estudo é avaliar o efeito de três diferentes tamanhos de pinos de fibras de quartzo (#0,5 – #2 - #3) na resistência à fratura de raízes dentárias. MATERIAL E MÉTODO: Neste estudo in vitro, 30 pré-molares mandibulares foram selecionados, seccionados, tratados endodonticamente e designados aleatoriamente em três grupos (n=10). Condutos foram preparados e pinos de fibras de quartzo (D.T. Light – Post TM) com três diferentes tamanhos (#0.5- #2 - #3) foram fixados, respectivamente em três grupos. Todos os pinos foram cimentados com cimento Panavia F 2.0. Pinos de resina foram construídos usando uma matriz pré-formada de poliéster. Os corpos de prova foram embebidos em blocos de resina acrílica com uma camada de ImpregumTM ao redor das raízes. Cargas compressivas na razão de 1 mm/min foram aplicadas axialmente na fossa central de cada corpo de prova, usando uma máquina universal de testes até a ocorrência de fratura radicular. Os dados foram submetidos à análise de variância. RESULTADOS: Não houve diferenças estatisticamente significantes na resistência à fratura entre os três grupos (P>0,05). A carga média de fratura foi 1010+-250.95 N para o grupo C, com o pino # 3. CONCLUSÕES: De acordo com os achados, tamanhos maiores de pinos de fibra não diminuem a resistência da estrutura radicular. Maiores diâmetros têm mais resistência à fratura e, além disso, pelo incremento da área de cimentação entre o pino e a parede da raiz, podem melhorar a união dentro da estrutura radicular e proporcionar mais estabilidade para o material de núcleo. Ao contrário de pinos metálicos de maior tamanho, os pinos de fibra de maior diâmetro aderem à estrutura radicular com mais eficiência. Como resultado, não reduzirão a resistência à fraturada raiz. Assim sendo, quando restaurarem-se dentes endodonticamente...

Mechanical Properties of Quartz Fiber Post / 대한치과보철학회지

The post core system has been used for reconstructon of severely damaged crown by caries or trauma.But problems such as crown exfoliation,post core fracture and root fracture have been reported. Ideal mechanical properties of the post require high fracture strength,high elastic limit and high resistance against fatigue and corrosion.Modulus of elasticity of the post should be similar with that of dentine.Low hardness is also required for the convenience of post removal in failure.Furthermore, the post itself must be translucent for the esthetical purpose.Several types of the post have been developed to satisfy the criteria above mentioned. The purpose of this study was to find out the mechanical properties of quartz fiber post by comparing with those of gold post and zirconia post. The results of this study were as follows : 1.Maximal fracture strength and stiffness of quartz fiber post were similar with those of gold post and zirconia post. 2.Young's modulus and hardness of quartz fiber post were lower than those of gold post and zirconia post. Mechanical property of quartz fiber post against post fracture was similar with that of gold post and zirconia post.Mechanical property of quartz fiber post against root fracture was higher than that of gold post and zirconia post.Quartz fiber post could be removed easily due to low hardness.