Comparison of the Effect for Fracture Resistance of Different Coronally Extended Post Length with Two Different Post Materials.

AIMS AND OBJECTIVES: To compare the effect for fracture resistance of different coronally extended post length with two different post materials. MATERIALS AND METHODS: One hundred and sixty endodontically treated maxillary central incisors embedded in acrylic resin with decoronated root portion were taken for the study. The postspaces were prepared according to standard protocol. The samples were divided into two groups according to the post material: glass-fiber post and Quartz fiber post. These groups were further subdivided on the basis of coronal extension of 4 and 6 mm for glass fiber and Quartz fiber posts, respectively. The posts were then luted with dual-polymerizing resin cement followed by core buildup. Samples were subjected to increasing compressive oblique load until fracture occurred in a universal testing machine. Data were analyzed with one-way ANOVA and independent Student's t-test. Analysis was done using SPSS version 15 (SPSS Inc., Chicago, IL, USA) Windows software program. RESULTS: Glass fiber post with coronal extension of 4 mm (182.8 N) showed better results than with 6-mm length (124.1 N). Similarly, in quartz fiber posts group, 4-mm postlength (314 N) was better when compared with 6 mm (160 N). The 4-mm coronal extension of quartz fiber post displayed superior fracture resistance. CONCLUSIONS: Glass fiber posts showed better fracture resistance than Quartz fiber posts. 4-mm coronal length showed more fracture resistance than 6 mm.

The effect of incomplete crown ferrules on fracture resistance and failure modes of endodontically treated maxillary incisors restored with quartz fiber post, composite core, and crowns.

AIM: To investigate the fracture resistance of restored endodontically treated teeth (RETT) with fiber posts, cores, and crowns with limited ferrules. MATERIALS AND METHODS: Sixty maxillary anterior teeth were endodontically treated and decoronated 2 mm above the cemento-enamel junction, and then divided into 6 groups of 10 teeth each; Group circumferential ferrule (2FR), Group ferrule in the labial, mesial, and palatal region (2FR-LaMPa), Group ferrule in the labial, and palatal region (2FR-LaPa), Group 2FR-Pa and 2FR-La respectively, and Group 0FR (no ferrule). All 60 prepared teeth were then restored with quartz fiber posts, resin composite cores, and metal crowns. The specimens were subjected to load until failure occurred. Data were analyzed using one-way analysis of variance and Tukey's tests (α = 0.05). The mode of failure was determined under a stereoscope. RESULTS: A statistical significant difference was found among groups 2FR-LaMPa, 2FR-Pa, 2FR-LaPa, and 2FR from the group 2FR-La, and from the group 0FR (P < 0.01). The predominant mode of failure was an oblique palatal to labial root fracture for the groups with remaining ferrules. CONCLUSION: For RETT that have incomplete crown ferrules, the location of the ferrules may affect their fracture resistance.

Evaluation of surface roughness and bond strength of quartz fiber posts after various pre-treatments.

PURPOSE: Debonding at the post-adhesive interface is a major problem for quartz fiber posts. The objective of this study was to evaluate surface roughness and bond strength of quartz fiber posts after various surface treatments. MATERIALS AND METHODS: Sixty-six quartz fiber posts were randomly divided into six experimental groups (n = 11) including group C, untreated (control); group SB, sandblasted; group SC, silica coated; group HF, hydrofluoric acid-etched; group N, Nd:YAG laser irradiated; group E, Er:YAG laser irradiated. Surface roughness of the posts was measured before and after pre-treatment. They were then bonded to resin cement and tensile bond strength was determined in a universal testing machine. Furthermore, two-way ANOVA and post hoc comparison tests (α = 0.05) were performed on all data. RESULTS: The highest mean force value was observed in group SB and followed by group E. Tukey's HSD test showed that there was no statistical difference between group SB and group E (p = 0.673). The highest mean roughness value was observed in group SB and a significant difference was found between group SB and all other groups (p < 0.001). This study reveals that sandblasting and Er:YAG laser irradiation provided a significant increase in bond strength between quartz fiber posts and resin cement. CONCLUSIONS: Sandblasting or Er:YAG laser-irradiation of the surface of the quartz fiber post before cementation is recommended for increasing retention.

Investigation of the effect of different prefabricated intracanal posts on fracture resistance of simulated immature teeth.

AIM: The aim of this study was to assess fracture resistances of simulated immature single-rooted teeth whose roots have been backfilled using 3 different post systems after a 4 mm apical mineral trioxide aggregate (MTA) placement. MATERIALS AND METHODS: Forty-eight maxillary anterior teeth were assigned into four groups. The lengths of each root were standardized by cutting off the coronal and apical portions to obtain 13 ± 1 mm samples and root canals were enlarged. The #6 Peeso reamers were allowed to protrude 1 mm beyond apex to simulate immature teeth. Apical 4 mm of each tooth was filled using MTA. The remaining portions were treated as follows: Group 1 (Control): AH Plus + Gutta-percha cold lateral compaction. Group 2: Glass fiber posts (FRC Postec Plus post) cemented using self-adhesive resin cement. Group 3: Quartz fiber posts (D.T. Light post) cemented using self-adhesive resin cement. Group 4: Zirconia posts (Cosmopost) were placed using self-adhesive resin cement. Specimens were embedded in self-curing acrylic. A compressive load was applied lingually at a crosshead speed of 1 mm/min at an angle of 45º until fracture in a universal testing machine. RESULTS: The mean fracture resistances were 823.17 ± 188.80, 1155.50 ± 190.37, 1208.00 ± 254.32, and 1153.25 ± 195.71 Newtons for Groups 1, 2, 3, and 4, respectively. All experimental groups had significantly higher fracture resistance compared with the control group (P < 0.01). No statistically significant difference was noted between the experimental groups (P > 0.05). CONCLUSIONS: All post systems exerted a similar reinforcing effect to a simulated immature tooth and may be preferred specifically in situations which require additional reinforcement.

Comparison of resilon and gutta-percha filling materials on root canal fracture resistance following restoring with quartz fiber posts.

OBJECTIVE: Bacterial leakage and root fractures are the most important reasons of root canal treatment failure. Due to the lack of adhesion of gutta percha to the canal walls, Resilon has been introduced as a root-filling material able to bond to the root walls. Metal posts may predispose the tooth walls to oblique and vertical fracture which usually leads to tooth loss; whereas, fiber posts may reinforce the remaining tooth structure. The purpose of this study was to compare the effect of Resilon and gutta-percha on the fracture resistance of root canal following restoring with quartz fiber posts. MATERIALS AND METHODS: Forty-four maxillary incisor root canals were chemo-mechanically prepared, then randomly divided into three groups: 1-Control group (n=20), 2-Experimental group (n=20) and a negative control group (n=4). Root filled teeth were restored with quartz fiber posts and composite resin cores. Four teeth with a conservative prepared access cavities and without any further post preparation were used as a negative control group. After simulating the clinical situation, specimens were loaded in the Universal Testing Machine for compressive strength test. All data were statistically analyzed by the T-test. RESULTS: The mean compressive strengths for group 1 was 535.8 ± 155.23 N and 645.93 ± 182.98N for group 2, which were statistically significant (p-value= 0.047). CONCLUSION: Root canals filled with Resilon were significantly more resistant than that of gutta-percha, following restoration with quartz fiber posts.

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 (α = .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...