Influence of sonic vibration and cement type on the bond strength of fiberglass posts after aging / Influencia de la vibración sónica y el tipo de cemento en la fuerza de unión de los postes de fibra de vidrio después del envejecimiento

Introduction: This study evaluated the influence of sonic vibration and thermocycling on the bond strength of fiberglass posts using conventional dual-cured and self-adhesive resin cements. Material and Methods: Ninety-six single-rooted endodontically treated teeth were divided randomly into eight groups according to the cement used (dual-cured or self-adhesive resin cement), use of sonic vibration during post accommodation, and aging conditions (24h in distilled water or 5,000 thermal cycles). The fiberglass posts (White Post DC1, FGM) were cleaned with alcohol, treated with silane and cemented with dual-cured (Allcem Core, FGM) or with self-adhesive resin cement (seT, SDI). For groups in which sonic vibration was used, the posts were accommodated, and sonic vibration was applied for 10 s using a special tip placed on top of the post (Sonic Smart Device, FGM). Pull-out tests were performed after storage in distilled water for 24h at 37°C or after thermocycling (5000 cycles, at 5°C and 55°C). The results were evaluated using three-way ANOVA and Tukey's test (α=0.05). Results: Significant differences were not observed between the bond strengths of dual-cured (87.93±41.81 N) and self-adhesive cement (82.53±41.43 N). Bond strength for the sonic vibration groups (100.36±42.35 N) was significantly higher than for groups without sonic vibration (70.13±34.90 N). There were significant differences between specimens subjected to thermocycling (98.33±39.42 N) and those stored for 24h in distilled water (72.16±39.67 N). Conclusion: It can be concluded that both sonic vibration and thermocycling significantly improved bond strength of fiberglass posts with the two evaluated resin cements.

Introducción: Este estudio evaluó la influencia de la vibración sónica y el termociclado en la fuerza de unión de los postes de fibra de vidrio utilizando cementos de resina autoadhesivos y de curado dual convencionales Material y Métodos: Se dividieron aleatoriamente noventa y seis dientes tratados endodónticamente de raíz única en ocho grupos según el cemento utilizado (cemento de resina de curado dual o autoadhesivo), el uso de vibración sónica durante la acomodación posterior y las condiciones de envejecimiento (24 horas agua destilada o 5.000 ciclos térmicos). Los postes de fibra de vidrio (White Post DC1, FGM) se limpiaron con alcohol, se trataron con silano y se cementaron con cemento de curado dual (Allcem Core, FGM) o con cemento de resina autoadhesivo (seT, SDI). Para los grupos en los que se utilizó vibración sónica, se acomodaron los postes y se aplicó la vibración sónica durante 10 s utilizando una punta especial colocada en la parte superior del poste (Sonic Smart Device, FGM). Las pruebas de extracción se realizaron después del almacenamiento en agua destilada durante 24 horas a 37ºC o después del termociclado (5000 ciclos, a 5ºC y 55ºC). Los resultados se evaluaron mediante ANOVA de tres vías y la prueba de Tukey (α = 0.05). Resultados: No se observaron diferencias significativas entre las resistencias de adhesión del cemento de curado dual (87,93 ± 41,81 N) y el cemento autoadhesivo (82,53 ± 41,43 N). La fuerza de unión para los grupos de vibración sónica (100,36 ± 42,35 N) fue significativamente mayor que para los grupos sin vibración sónica (70,13 ± 34,90 N). Hubo diferencias significativas entre los especímenes sometidos a termociclado (98,33 ± 39,42 N) y los almacenados durante 24 h en agua destilada (72,16 ± 39,67 N). Conclusión: Se puede concluir que tanto la vibración sónica como el termociclado mejoraron significativamente la fuerza de unión de los postes de fibra de vidrio con los dos cementos de resina evaluados.

Stress analysis of maxillary central incisors endodontically -treated with varying ferrule heights and three different post dowel materials - a finite element analysis / Análisis de tensión de los incisivos centrales superiores tratados endodónticamente con diferentes alturas de férula y tres materiales diferentes de clavija posterior: un análisis de elementos finitos

Statement of problem : fracture of endodontically treated teeth is reduced by the use of a post with ferrule, but the effect of different ferrule configurations and dowel materials is not clear. Purpose: to evaluate the effect of ferrules with different configurations and heights on the stress of endodontically treated teeth restored with three different post and dowel materials. Materials and Methods: fifteen models of maxillary central incisors restored with porcelain fused to metal crowns were obtained using pro engineer software. the models were divided into three groups, each consisting of five models with ferrule heights of 0mm, 2mm, 4mm, 2mm with oblique fracture, 4mm with oblique fracture, the models under group GFR were restored with fiberglass reinforced post (GFR) and composite core build-up, group NiCr with a custom cast post metal alloy (NiCr), and group Zr with zirconia post (Zr) and composite core build-up. an oblique load of 100N and 150N at an angle of 135 degrees was applied to the palatal surface of the tooth, a vertical load of 100N and 150N at an angle of 90 degrees was applied to the incisal tip of the tooth. The maximum principal stress and the von mises stress was calculated for the remaining tooth structure and post apex using the finite element analysis (FEA) software. Results: the maximum von misses stress was observed in the apex of the post (p<0.05). Group Zr showed the highest mean stress (6.39Mpa) followed by group NiCr (5.65Mpa). There was a significant difference between post and between NiCr and Zr post for 2mm and 4mm ferrule height, while for 0mm ferrule there was a significant difference between the GFR and NiCr groups (p<0.05). Under oblique load, the maximum mean stress was observed in remaining tooth structures while for vertical load, it was observed at the apex of the post. Regarding ferrule heights, there were significant differences between 0mm-2mm, and 0mm-4mm uniform ferrule in post apex in the case of NiCr posts (p<0.05). Absence of ferrule resulted in higher stress for the NiCr group. Conclusion: higher loads that led to fracture were observed only at the apex of the post. Zirconia posts (group Zr) had higher fracture loads, whereas absence of ferrule resulted in higher fracture load with custom cast posts (group NiCr). Fracture thresholds were high on the remaining tooth structure for all the dowel systems especially for composite core build up irrespective of ferrule height and configuration. Clinical implications: appropriate selection of post and dowel materials in different configurations of ferrule heights ensures clinical success.

Indicación del problema: la fractura de los dientes tratados endodónticamente se reduce mediante el uso de un poste con férula, pero el efecto de diferentes configuraciones de férula y materiales de clavija no está claro. Propósito: evaluar el efecto de los casquillos con diferentes configuraciones y alturas sobre el estrés de los dientes tratados endodónticamente restaurados con tres materiales diferentes de postes y tacos. materiales y métodos: quince modelos de incisivos centrales superiores restaurados con porcelana fundida a coronas de metal se obtuvieron con el software Pro Engineer. Los modelos se dividieron en tres grupos, cada uno de los cuales consta de cinco modelos con alturas de casquillo de 0mm, 2mm, 4mm, 2mm con fractura oblicua, 4mm con fractura oblicua. los modelos del grupo GFR fueron restaurados con poste reforzado con fibra de vidrio (GFR) y acumulación de núcleo compuesto, grupo nicr con una aleación de metal de poste fundido personalizado (NiCr) y grupo Zr con poste de zirconia (Zr) y acumulación de núcleo compuesto. se aplicó una carga oblicua de 100N y 150N en un ángulo de 135º a la superficie palatina del diente. se aplicó una carga vertical de 100N y 150N en un ángulo de 90º a la punta incisal del diente. la tensión principal máxima y la tensión de von mises se calcularon para la estructura dental restante y después del vértice utilizando el software de análisis de elementos finitos (FEA). Resultados: el estrés máximo de von falta se observó en el vértice de la publicación (p<0.05). El grupo Zr mostró el mayor estrés medio (6.39Mpa) seguido del grupo NiCr (5.65Mpa). Hubo una diferencia significativa entre la publicación NiCr y Zr para la altura de la férula de 2mm y 4mm, mientras que para la férula de 0mm hubo una diferencia significativa entre los grupos GFR y NiCr (p<0,05), bajo la carga oblicua, la tensión media máxima en las estructuras dentales restantes, mientras que para la carga vertical, se observó en el vértice del poste. En cuanto a las alturas de la férula, hubo diferencias significativas entre la férula uniforme de 0mm-2mm y de 0mm-4mm en el post-apex en el caso de los postes de NiCr (p<0.05), la ausencia de férula dio como resultado un mayor estrés para el grupo NiCr. Conclusión: las cargas más altas que llevaron a la fractura se observaron solo en el vértice del poste; Los postes de zirconia (grupo Zr) tuvieron mayores cargas de fractura, mientras que la ausencia de férula dio como resultado una mayor carga de fractura con postes moldeados personalizados (NiCr de grupo). Los umbrales de fractura fueron altos en la estructura dental restante para todos los sistemas de clavijas, especialmente para la acumulación de núcleos compuestos independientemente de la altura y configuración de la férula. Implicaciones clínicas: la selección adecuada de materiales de postes y tacos en diferentes configuraciones de alturas de férulas asegura el éxito clínico.

Clinical observation of the restoration of computer aided designed and manufactured one-piece zirconia posts and cores: a 5-year prospective follow-up study / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the effect of computer aided design and computer aided manufacture (CAD/CAM) one-piece zirconia posts and cores for the restoration of defective teeth.@*METHODS@#In the study, 72 defective teeth of 47 patients who had proper root canal therapy were restored with CAD/CAM one-piece zirconia posts and cores. All the ceramic crowns were finally used to restore contour and function of the teeth. The defective teeth were divided into two groups on the basis of the teeth defect degree. Group A: 39 defective teeth presented with three or four coronal residual walls, and group B: 33 defective teeth presented with less than two coronal residual walls. During the clinical observation period, the stability, dislocation of posts and the occurrence of fractures in either teeth or posts and cores were assessed and analyzed with a paired t test(α=0.05). Meanwhile shade matching was conducted between the restored teeth and normal reference teeth, the marginal fitness of the restored teeth were recorded according to the standard of United States Public Health Service (USPHS) and analyzed with descriptive statistics.@*RESULTS@#The average follow up was (65.0±4.8) months. During the observation period, the restorations were examined both clinically and with periapical radiograph. No incidence of teeth fracture or posts and cores complications were observed in both groups, and all CAD/CAM one-piece zirconia posts and cores remained intact with restored teeth. There were no post and core dislodgement or fracture. There was no difference between group A and group B (P>0.05). The restorative effect of CAD/CAM one-piece zirconia posts and cores with all the ceramic crowns were assessed according to the standard of USPHS, and the number of the restored tooth shade matching with level A was 67, and 5 with level B. The rate of shade matching was 93.06%. As the marginal fitness, 64 restored teeth were level A, and 8 with level B. The rate of restorative teeth marginal fitness was 88.89%.@*CONCLUSION@#CAD/CAM one-piece zirconia posts and cores were successfully used to restore defective teeth and received excellent clinical effect. So, it can be a good choice for defective teeth which need post-cores and crowns restoration.

Does the Moment of Fiber Post Cutting Influence on the Retention to Root Dentin?

Despite several advantages associated with pre-fabricated glass-fiber posts, the coronal portion of these posts must be cut to allow their use in various clinical situations. However, cutting the cemented post can generate stress on the bonding interface and affect the bond strength. The aim of this study was to investigate the effect the of fiber post cutting on the bond strength of root canals. Sixty bovine incisor roots were included in resin cylinders with simulated periodontal ligaments. Glass-fiber posts were luted using regular resin cement RelyX ARC (3M ESPE) or self-adhesive cement RelyX Unicem (3M ESPE). The posts were cut prior to cementation, immediately after luting or after building up the core (n=10). After storage for 24 h, the samples were cut and subject to push-out testing using a mechanical testing machine (EMIC DL 2000). Data were analyzed using two-way ANOVA (resin cement x moment of post cutting) and Tukey's post hoc test (α=0.05). The moment of fiber post cutting did not affect the bond strength when Unicem was used. However, the bond strength was reduced when ARC was used and when the post was cut immediately. In conclusion, the moment of fiber post cutting may affect the retention of root canal posts when a regular resin cement is used.

Apesar das diversas vantagens associadas aos pinos de fibra de vidro pré-fabricados, o corte da sua porção coronária deve ser realizado para permitir seu uso em algumas situações clínicas. Entretanto, o corte do pino cimentado pode gerar tensões na interface adesiva e afetar a resistência de união. O objetivo deste estudo foi avaliar o efeito do momento do corte do pino na resistência de união ao canal radicular. Sessenta raízes de incisivos bovinos foram incluídas em cilindros de resina com simulação do ligamento periodontal. Pinos de fibra de vidro foram cimentados utilizando um cimento resinoso convencional RelyX ARC (3M ESPE) ou autoadesivo RelyX Unicem (3M ESPE). Os pinos foram cortados previamente à cimentação, imediatamente após a cimentação, ou após a reconstrução do núcleo de preenchimento (n=10). Após o armazenamento por 24 h, as amostras foram seccionadas e submetidas ao ensaio de cisalhamento por extrusão utilizando máquina de ensaio mecânico (EMIC DL 2000). Os dados foram analisados por ANOVA dois fatores (cimento resinoso x momento do corte do pino) e teste de Tukey (=0,05). O momento do corte do pino de fibra de vidro não afetou a resistência de união quando o RelyX Unicem foi utilizado. No entanto, o corte do pino imediatamente após a cimentação reduziu os valores de resistência de união quando o RelyX ARC foi utilizado. Em conclusão, o momento do corte do pino pode afetar a resistência de união ao canal radicular quando o cimento resinoso convencional for utilizado.

Effect of root canal preparation, type of endodontic post and mechanical cycling on root fracture strength

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. .

Reorientation simplified: A device for recording and reproducing the path of insertion for removable partial dentures.

Aim: The record of path of insertion on the dental cast is part of the dentist's work authorization to the dental laboratory technician. The path of insertion record enables the dental technician to replace the cast on a surveyor in the same position that the dentist selected. Analysis of factors that influence the path of insertion should determine a path of insertion that will reduce the potential for dislodgement and promote stability of removable partial denture (RPD). Materials and Methods: The recording of the relation of a cast to a dental surveyor and the transfer of this relationship to the dental laboratory may be done by tripodization, by scoring the base of the cast, or by cementing a reference pin on the cast. Conclusion: Recording the established path of insertion can be difficult when the procedure uses a cemented pin and the casts are mounted in an articulator. This article describes a procedure for innovative dowel pin and sleeve device to record the path of insertion of RPDs, which serves the same purpose as the cemented pin but can be easily removed and replaced.

Tensile Strength of Glass Fiber Posts Submitted to Different Surface Treatments

The aim of this in vitro study was to evaluate the tensile strength of glass fiber posts submitted to different surface treatments. Forty-eight maxillary canines had their crowns sectioned and root canals endodontically treated. The roots were embedded in acrylic resin and distributed into 3 groups according to the surface treatment: Group I: the posts were treated with silane agent for 30 s and adhesive; Group II: the posts were cleaned with alcohol before treatment with silane agent and adhesive; Group III: the posts were submitted to conditioning with 37% phosphoric acid for 30 s before treatment with silane agent and adhesive. Each group was divided into 2 subgroups for adhesive polymerization or not before insertion into the canal: A - adhesive was not light cured and B - adhesive was light cured. All posts were cemented with Panavia F and the samples were subjected to tensile strength test in a universal testing machine at crosshead speed of 1 mm/min. Data were submitted to one-way ANOVA and Tukey's test at 5% significance level. There was statistically significant difference (p<0.01) only between group GIII-B and groups GI-A and GI-B. No significant difference was found among the other groups (p>0.05). It was concluded that the products used for cleaning the posts influenced the retention regardless of adhesive light curing.

O objetivo deste estudo in vitro foi avaliar a resistência à tração de pinos de fibra de vidro submetidos a diferentes tratamentos de superfície. Quarenta e oito caninos superiores tiveram suas coroas seccionadas e as raízes tratadas endodonticamente. As raízes foram incluídas em resina acrílica e distribuídas em 3 grupos de acordo com o tratamento de superfície aplicado aos pinos: Grupo I: os pinos receberam agente silano por 30 s e adesivo; Grupo II: os pinos foram limpos com álcool e então receberam o agente silano e adesivo; Grupo III: os pinos foram submetidos ao condicionamento com ácido fosfórico a 37% por 30 s, seguido de agente silano e adesivo. Cada grupo foi dividido em 2 subgrupos de acordo com fotoativação do adesivo antes da inserção do pino no interior do canal: A – adesivo não foi fotoativado, B: o adesivo foi fotoativado. Todos os pinos foram cimentados com Panavia F e as amostras foram submetidas a teste de tração utilizando máquina universal de ensaios, com velocidade de 1 mm/min. Os dados obtidos foram submetidos à ANOVA a um critério e ao teste de Tukey com nível de significância de 5%. Houve diferença estatisticamente significante (p<0,01) entre o grupo GIII-B e os grupos GI-A e GI-B. Os demais grupos não apresentaram diferenças significantes entre si (p>0,05). Pode-se concluir que as substâncias utilizadas para a limpeza dos pinos interferiram em sua retenção, independente da fotopolimerização do adesivo.

Influence of Endodontic Sealer Composition and Time of Fiber Post Cementation on Sealer Adhesiveness to Bovine Root Dentin

This study aimed to assess the influence of the type of endodontic sealer (salicylate resin-based sealer vs. two endodontic sealers) and the time of fiber post cementation after root filling on the post adhesion to bovine root dentin. Sixty bovine roots were assigned to six groups (n=10), considering an experimental design with two factors (factorial 3x2): endodontic sealer factor in three levels [epoxy resin-based sealer (AH Plus), eugenol-based sealer (Endofill), and salicylate resin-based sealer plus mineral trioxide aggregate - MTA (MTA Fillapex)] and time for post cementation factor in two levels (immediate post cementation or 15 days after root canal filling). After post cementation, 2-mm-thick slices were produced and submitted to push-out test. The failure modes were analyzed under a 40× stereomicroscope and scored as: adhesive at cement/dentin interface; adhesive at cement/post interface; cement cohesive; post cohesive; dentin cohesive; or mixed. Data were analyzed using two-way ANOVA and Tukey's post-hoc tests (α=0.05). When the fiber posts were cemented immediately after the root canal filling, the bond strengths were similar, independent of the endodontic sealer type. However, after 15 days, the epoxy resin-based sealer presented higher bond strength than the other sealers (p<0.05). Comparison between each sealer in different experimental times did not reveal any differences. The main failure type was adhesive at dentin/cement interface (89.4%). The time elapsed between the root canal filling and post cementation has no influence on post/root dentin adhesion. On the contrary, the type of endodontic sealer can influence the adhesion between fiber posts and root dentin.

Este estudo objetivou avaliar a influência do tipo de cimento endodôntico (um cimento à base de resina de salicilato e dois cimentos endodônticos) e do tempo decorrido entre a obturação do conduto e a cimentação do pino de fibra na adesão de pinos de fibra à dentina radicular bovina. Sessenta dentes bovinos foram divididos em seis grupos (n=10), considerando um desenho experimental de dois fatores (3x2): cimento endodôntico em três níveis [à base de resina epóxica (AH Plus), eugenol (Endofill) e resina de salicilato e MTA (MTA Fillapex)] e o tempo para cimentação em dois níveis (cimentação imediata e 15 dias pós a obturação). Após cimentação do pino de fibra, fatias com 2 mm de espessura foram obtidas e submetidas ao teste de push-out. Os padrões de falha foram analisados em estereomicroscópio (40×) e classificados em: adesiva na interface cimento/dentina, adesiva cimento/pino, coesiva do cimento, coesiva do pino, coesiva da dentina e mista. Os dados foram analisados através dos testes de ANOVA a dois fatores e post hoc de Tukey (α=0,05). Quando os pinos de fibra foram cimentados imediatamente após a obturação dos condutos, a resistência adesiva foi similar, independentemente do tipo de cimento endodôntico. Entretanto, após 15 dias, os dentes obturados com cimento resinoso à base de resina epóxica apresentaram os maiores valores de resistência adesiva (p<0,05). Os valores de resistência adesiva do mesmo cimento nos diferentes tempos experimentais não foram alterados. O principal tipo de falha foi adesiva na interface cimento/dentina (89,4%). O tempo decorrido entre a obturação dos condutos e a cimentação do pino não influenciou a adesão do pino de fibra à dentina radicular. Por outro lado, o tipo de cimento endodôntico influencia a adesão entre dentina radicular e pinos de fibra.

Fracture resistance of bovine incisors restored with different glass fiber posts: Effect of the diameter of fiber post.

Aim: Compare the effect of three post designs on the fracture resistance and failure modes of composite core - fiber post - crownless tooth sets. Materials and Methods: Ninety bovine incisors were selected and divided into nine groups of 10 specimens. The teeth were assigned to three groups based on the post design: Cylindrical, tapered, and double-tapered. Each group was subdivided into three subgroups in accordance with the diameter of the post: Small (No.1), medium (No.2), and large (No.3). The Panavia F system was used for post cementation. The specimens were mounted in acrylic resin blocks with a layer of silicone rubber covering the roots. A universal testing machine compressively loaded the specimens from the palatal side at a crosshead speed of 1 mm/min and at an angle of 135Ί to the long axis of the teeth, until failure occurred. The failure mode was determined by a stereomicroscope inspection of all the specimens. Data were analyzed by one-way ANOVA and the Tukey test (P < 0.05). Results: The fracture resistance was affected by the type of post (P < 0.0001). A narrower diameter for all of the post systems allowed for higher resistance. The main failure mode in the large cylindrical group was catastrophic fractures, while the main failures in the other eight groups were favorable. Conclusion: Narrower diameter posts showed higher fracture resistance. The dominant failure pattern was repairable fracture, except for those with large cylindrical groups.

Comparative evaluation of the regional micro-push-out bond strength of custom-made resin post system with a prefabricated resin post: An in vitro study.

Aim : The purpose of the study is to compare the regional micro-push-out bond strength of custom-made resin post and a prefabricated resin post luted using self-etch adhesive and/or etch and rinse adhesive system at various regions. Materials and Methods : Forty freshly extracted human maxillary central incisors were selected for this study; 1.5-2-mm coronal to the cemento-enamel junction was removed with a diamond disk using a slow speed handpiece under cooling water. Working lengths were established, root canals were sequentially enlarged upto the apex until ISO size 50-K-file and obturated using gutta-percha and AH plus sealer by cold lateral compaction. Post spaces were prepared to a depth of 10 mm using paeso-reamer upto size #3. After preparation, each specimen was embedded in chemically cured acrylic resin. The roots were randomly assigned to four groups: Group I: Custom-made resin post+Self-etch adhesive, Group II: Glass FRC post+Self-etch adhesive, Group III: Custom-made resin post+Etch and Rinse adhesive, Group IV: Glass FRC post+Etch and Rinse adhesive. Fabrication of custom-made resin post was done. All the posts were cemented using a dual cure resin luting cement. Each root was sectioned perpendicular to the long axis using a microtome and subjected to micro-push-out bond strength. Results: The micro-push-out bond strength in the coronal region, in Group I 13.5±1.66 MPa, Group II 12.08±0.8 MPa, Group III 11.15±1.06 MPa, Group IV 11.81±1.11 MPa. In the middle third region: Group I 11.43±0.740 MPa, Group II 10.584±0.504 MPa, Group III 10.0582±0.830 MPa, Group IV 10.35±0772 MPa. In the apical third: Group I 10.38±0.878 MPa, Group II 9.59±1.06 MPa, Group III 9.34±0.73o MPa, Group IV 8.77±1.02 MPa. Conclusion : Within the limitations of the study, amongst all the four groups tested, custom-made resin post luted with self-etch system (CMPR-SE) showed higher micro-push-out bond strength values in all regions when compared to the other groups.

Adaptación e integridad del cementado de endopostes de fibra de cuarzo con la técnica de inyectado en conductos radiculares amplios / Adaptation and integrity of luted fiber posts in wide root canals with injected tecnhique

La presente investigación estudió la adaptación e integridad existente entre el cemento, poste de fibra y la dentina radicular en dientesbovinos, analizando la presencia de burbujas en las interfaces involucradas en la fijación de este tipo de retenedores intra-radiculares ydiferentes medios de fijación resinosos, dependientes de un sistema adhesivo auto-acondicionante, auto-adhesivos, e ionoméricos. Semodificaron los protocolos de cementación a manera de propuesta para la mejor adaptación del agente cementante al substrato radiculary al poste de fibra.El presente estudio ha evidenciado que factores como el acondicionamiento del conducto y la técnica de inserción del poste de fibrasimultáneamente con el medio de fijación influyen notablemente en los resultados.Fue cuestionada la técnica de embadurnado del poste y del empleo de ácido fosfórico como acondicionador de la dentina radicular; por elcontrario se propone la técnica de inyectado y el empleo de EDTA para medios de fijación resinosos dependientes de sistemas adhesivos,como también el empleo de ácido poliacrílico como acondicionador previo al uso de cemento de ionómero vítreo modificado con resina.

This research studied the adaptation and integrity between the cement, the fiber post and the root dentin in bovine teeth by analyzing thepresence of bubbles in the interfaces involved in the luting of posts, different self-etch dependent resin type luting agents, self-adhesiveresin luting agents and resin modified glass ionomer luting cement. Protocols were modified by way of cementing proposal for thebetter adaptation of luting agent to dentin substrate and fiber post. This study has shown that factors such as conditioning of the rootcanal dentin and the insertion technique of the fiber post with the luting agent significantly affect the results. Smeared post techniqueand the use of phosphoric acid as root dentin conditioner was questioned; on the other hand, an injection technique and the use of EDTAfor dependent adhesive systems luting agents are proposed as well as the use of polyacrylic acid as a conditioner prior the use of resinmodified glass ionomer cement.

Cementado de postes de fibra con cementos híbridos de ionómero vítreo: estudio de las interfases por microscopía electrónica de barrido (MEB) / Cementing fiber posts with hybrid glass-ionomer cements: an SE evaluation of the post-cement-root dentin interfaces

Estudio de las interfases poste de fibra-cemento de ionómero híbrido-dentina evaluando dos cementos.Objetivos: El objetivo de este estudio fue analizar las interfases, la estructura y el sellado entre la dentina radicular y los postes de fibra.Las interfases se obtuvieron cementando los postes con dos marcas comerciales de cemento previo acondicionamiento de la dentinacon acondicionador dentinario (Cavity Conditioner, GC Corp). Las interfases fueron evaluadas en su continuidad entre poste, cementoy dentina. La estructura del cemento también fue evaluada.Método: Se realizó la endodoncia en veinte dientes uniradiculares extraídos por razones periodontales que fueron separados al azar endos grupos de 10 dientes cada uno: grupo 1: Fuji Plus (GC); grupo 2: Meron Plus (VOCO). Luego del tallado del canal para el poste yaplicación del acondicionador dentinario cada espécimen recibió un poste de fibra de cuarzo translúcido y radiopaco Macro-Lock (RTD)que se cementó con uno de los dos cementos híbridos de acuerdo a las indicaciones del fabricante. Luego de ser almacenadas por 48horas a temperatura ambiente en suero fisiológico, 10 raíces fueron seccionadas transversalmente en 3 partes y 10 longitudinalmente enmitades. Se realizó la preparación de los especímenes para microscopía electrónica de barrido (MEB) con el fin de observar las interfasesy de realizar el análisis por Energía Dispersiva de Rayos X (EDX) de algunas estructuras identificadas por MEB en las mismas.Resultados: El examen por MEB reveló una interfase perfecta entre el ionómero y la pared radicular. Por otra parte la interfase postecementomostró zonas sin adhesión.La MEB también reveló numerosas burbujas de aire con cuerpos esféricos en su interior en el espesor del cemento. Los análisis porEDX mostraron una periferia densa con un contenido de Al y Si mayor que la matriz del ionómero circundante.Conclusiones: los cementos híbridos de ionómero de vidrio proveen una...

Morphological study of fiber post/hybrid glass ionomer cement/dentin interface by evaluation of two cements.Objectives: The aim of the study was to analyze the interfaces, the structure and the seal between root dentin and cemented fiber posts.The interfaces were obtained by cementing the posts with two brands of cements both used after application of polyacrilic acid (CavityConditioner, GC Corp). . The interfaces were evaluated by SEM observation of the continuity between the fiber posts, the cement andthe root dentin. The structure of the cements were also evaluated.Method: Twenty single rooted teeth extracted for periodontal reasons were treated endodontically and then randomly separated into twogroups of 10 teeth each: group 1: Fuji Plus (GC); group 2: Meron Plus (VOCO). After preparation of the root canal and application ofthe cavity conditioner (Cavity Conditiones GC Co) each specimen received a Macro-Lock Post (RTD), a serrated, translucent radiopaquequartz fiber post that was cemented with one of the two hybrid cements according to the manufacturer’s instructions. After storage at roomtemperature for 48 hours in physiological saline solution, 10 roots were sectioned transversally into 3 pieces and 10 roots longitudinally.The specimens were then prepared for SEM observation of the structure and continuity of the interfaces and EDX of various structuralphases identified by SEM along the interfaces.Results: SEM revealed a perfectly sealed interface between glass ionomer and root dentin. In the other hand, the fiber post-cementinterface was the fiber post-cement interfase evidence zones of no-adhesion.SEM also revealed numerous air voids with spherical bodies inside within the RMGI matrix. EDX analyses of the spherical body showedan electron dense perifery with a higher Al and Si content than the surrounding ionomer.Conclusion: Hybrid glass ionomer cements provide a perfectly sealed interface with root dentin...

Distribuição das tensões relacionadas ao uso de retentores em dentes tratados endodonticamente utilizando o método dos elementos finitos / Stress distribution related to the use of retainers in endodontically treated teeth using the finite element method

A restauração dos dentes tratados endodonticamente, com grande fragilidade de suas estruturas, traz dúvidas ao clínico quanto à melhor forma de atuar nesses elementos. Os retentores intrarradiculares, sejam núcleos metálicos fundidos ou pré-fabricados, são geralmente necessários para a restauração destes elementos. Cada um desses materiais imprime uma força diferente nas estruturas adjacentes, sendo o entendimento destas uma necessidade para a melhor escolha e aplicação clínica do retentor. Objetivo: A proposta do presente trabalho é analisar e avaliar a distribuição de tensões no complexo dente-periodonto pelo método dos elementos finitos bidimensional com a utilização de diferentes tipos de retentores. Método: Este estudo tem por base modelos matemáticos de um canino superior tratado endodonticamente com a utilização de retentores intrarradiculares metálicos fundidos em NiCr, metálicos pré-fabricados em titânio. Os modelos foram submetidos a uma carga de 100 N por palatina em um ângulo de 45º. A análise e avaliação das tensões foram realizadas para cada um dos modelos e seus diferentes tipos de pinos. Resultados: A maior concentração de tensões se deu com o uso do pino metálico pré-fabricado de titânio, com valores de tração que oscilam entre 1.207 MPa a 4.878 MPa e de compressão entre -9.806 MPa a -2.464 MPa. O pino metálico fundido imprimiu tensões de menores valores, mais homogêneas e uniformes, tendo seus valores de tração variando de 1.287 MPa a 4.919 Mpa e seus valores de compressão variando de -9.607 MPa a 2.344 Mpa. Conclusão: Os pinos intrarradiculares metálicos pré-fabricados de titânio geram forte estresse no sistema dente-periodonto, sendo o menos indicado clinicamente. O mais indicado para uso clínico foi o pino metálico fundido, cuja tensão se manifestou de maneira mais uniforme no elemento dentário.

The restoration of endodontically treated teeth with great structure fragility challenges the clinician about the best way to proceed on these elements. The use of intracanal retainers, either post and core systems of prefabricated posts, is usually necessary to restore this kind of teeth. Each one of these materials exerts a different force on the adjacent structures and understanding these forces is mandatory for a better choice and clinical application of intracanal retainers. Objective: The purpose of this study was to analyze and evaluate the stress distribution in the tooth-periodontium complex by the two-dimensional finite element method, using different types of retainers. Methods: This study was based on mathematical models of an endodontically treated maxillary canine, using a NiCr cast intracanal posts and a prefabricated titanium post. The models were subjected to a 100 N load directed palatally at a 45º angle. The strains for each of the models and different types of post were analyzed and evaluated. Results: The highest stress concentration occurred with the use of the prefabricated titanium post, with traction values ranging from 1207 MPa to 4878 MPa and compression values between -9806 and -2464 MPa. The NiCr cast post exhibited lower tension values, with a more homogeneous and uniform distribution, traction values ranging from 1287 MPa to 4919 MPa and compression values ranging from -9607 MPa to 2344 MPa. Conclusion: Prefabricated titanium intraradicular posts induced strong stress to the tooth-periodontium complex and is less indicated clinically. The metal cast post appears more adequate cast for clinical use, as the resulting tension was distributed more uniformly along the tooth.

A finite element thermal analysis of various dowel and core materials.

Aim: Thermal analysis of the temperature and stress distribution of parallel sided, threaded and non-threaded dowels and core materials under thermal loading within a maxillary central incisor using a three dimensional finite element study. Materials and Methods: 3D models of endodontically treated maxillary central incisor with parallel sided, threaded and non- threaded post and core materials were simulated using the ANSYS software. Materials simulated were parallel sided cast gold post and core, parallel sided fibre reinforced composite (FRC) post and core, and parallel sided, threaded, prefabricated stainless steel post and amalgam core. Thermal loads simulating hot (60 degree C/ 333K) and cold (15 degree C/288K) liquid were applied for 15 seconds at the incisal edge. The temperature changes at the selected nodes were obtained on the various post and core materials, interface between post and dentin, interface between core and dentin, within the dentin and within the cement layer. Results: Temperature and stress distribution pattern were represented in numerical and color coding and results interpreted. Thermal stresses arises as a result of temperature changes. A decreased temperature gradient of the metallic dowels and core (T1 hot - 0.002K, T3 hot - 1.071K, T1 cold -0.99K, T3 cold - 0K) were obtained than that of the FRC dowel and core of 1.982K(hot) and1.55K(cold) respectively due to the higher thermal conductivity of the metals. Higher thermal stress values of 3.567 Mpa(hot) and 3.092 Mpa(cold) respectively were obtained for the FRC dowels and higher stress values of 39.679 Mpa(hot) and 57.855 Mpa(cold) respectively were also obtained for the FRC cores. These values indicated that thermal stresses of the FRC dowel and core were greater than that of cast gold dowel and core and prefabricated stainless steel dowel and amalgam core due to its high coefficient of thermal expansion. Maximum stress values of the FRC dowel and core of 1.87 Mpa(hot) and 2.57 Mpa(cold) respectively were also generated in the cement layer, core and metal ceramic crown. The junction of the metal ceramic crown and dentin demonstrated the maximum stress. Higher thermal stress values of 59.162 ± 10 Mpa were obtained in the restoration and the coronal portion of the dentin than the stress levels of .0039 ± 10Mpa in the supporting bone due to an increased thermal expansion. Conclusion: Non-metallic dowel and core materials such as fibre reinforced composite dowels (FRC) generate greater stress than metallic dowel and core materials. This emphasized the preferable use of the metallic dowel and core materials in the oral environment.

Comparison of different ultrasonic vibration modes for post removal

This in vitro study compared different ultrasonic vibration modes for intraradicular cast post removal. The crowns of 24 maxillary canines were removed, the roots were embedded in acrylic resin blocks, and the canals were treated endodontically. The post holes were prepared and root canal impressions were taken with self-cured resin acrylic. After casting, the posts were cemented with zinc phosphate cement. The samples were randomly distributed into 3 groups (n=8): G1: no ultrasonic vibration (control); G2: tip of the ultrasonic device positioned perpendicularly to core surface and close to the incisal edge; and G3: tip of the ultrasonic device positioned perpendicularly to core surface at cervical region, close to the line of cementation. An Enac OE-5 ultrasound unit with an ST-09 tip was used. All samples were submitted to the tensile test using an universal testing machine at a crosshead speed of 1 mm/min. Data were subjected to one-way ANOVA and Tukey's post-hoc tests (α=0.05). Mean values of the load to dislodge the posts (MPa) were: G1 = 4.6 (± 1.4) A; G2 = 2.8 (± 0.9) B, and G3= 0.9 (± 0.3) C. Therefore, the ultrasonic vibration applied with the tip of device close to the core's cervical area showed higher ability to reduce the retention of cast post to root canal.

Este estudo in vitro comparou diferentes modos de vibração ultra-sônica na remoção de pinos intra-radiculares fundidos. As coroas de 24 caninos superiores foram removidas, as raízes foram incluídas em blocos de resina acrílica e tratadas endodonticamente. Os espaços para os pinos intra-radiculares foram preparados e depois moldados com resina acrílica autopolimerizável. Após a fundição, os pinos intra-radiculares foram cimentados com cimento de fosfato de zinco. As amostras foram distribuídas aleatoriamente em três grupos (n=8): G1: sem vibração ultra-sônica (controle), G2: ponta do aparelho ultra-sônico posicionada perpendicularmente à superfície do núcleo e perto da borda incisal e G3: ponta do aparelho ultra-sônico posicionada perpendicularmente à superfície do núcleo na região cervical, perto da linha de cimentação. Uma unidade de ultra-som Enac OE-5 com uma ponta ST-09 foi usada. Todas as amostras foram submetidas ao teste de tração utilizando máquina universal de ensaios a uma velocidade de 1 mm/min. Os dados foram submetidos aos testes ANOVA e Tukey post-hoc (α = 0,05). Os valores médios de carga para deslocar os pinos (MPa) foram: G1 = 4,6 (± 1,4) A; G2 = 2,8 (± 0,9), B e G3 = 0,9 (± 0,3) C. Portanto, a vibração ultra-sônica aplicada com a ponta do dispositivo perto da zona cervical do núcleo apresentou maior capacidade de reduzir a retenção de pinos metálicos fundidos no canal radicular.

Effect of light-activation with different light-curing units and time intervals on resin cement bond strength to intraradicular dentin

The aim of this study was to assess the bond strength of a resin cement to intraradicular dentin varying the light-curing unit and the moment at which the light was applied. Post spaces of endodontically treated canines were prepared. The roots were distributed into 6 groups (n=10) according to the light-curing unit and the moment of light exposure: I) Quartz tungsten halogen-600 mW/cm² (QTH) + immediate light activation (t0); II) QTH + light activation after 10 min (t10); III) Light-emitting diodes (LED)-800 mW/cm² (LED-800)+ t0; IV) LED-800 + t10; V) LED-1,500 mW/cm² (LED-1500)+ t0; VI) LED-1500 + t10. After post cementation, slices from coronal, middle and apical post/root regions were submitted to the push-out test and failure evaluation. It was verified that LED-800 (4.40 ± 3.00 MPa) and LED-1500 (4.67 ± 3.04 MPa) provided bond strength statistically superior to QTH (3.13 ± 1.76 MPa) (p<0.05), and did not differ from each other (p>0.05). There was no significant difference between t0 and t10 (p>0.05). Coronal post/root region (4.75 ± 3.10 MPa) presented significantly higher bond strength than the apical (3.32 ± 2.30 MPa) (p<0.05) and middle regions (4.14 ± 2.99 MPa) showed intermediate values. Adhesive failures were predominant when using QTH. Adhesive and mixed failures occurred more frequently in the apical region. Higher adhesion of the resin cement to intraradicular dentin was observed in the coronal region with LED light-activation, regardless of the moment of light exposure.

O objetivo deste estudo foi avaliar a resistência de união do cimento resinoso à dentina intrarradicular em função da fonte fotoativadora e do momento de aplicação da luz. Os espaços para cimentação dos pinos foram preparados em caninos tratados endodonticamente. As raízes foram distribuídas em seis grupos (n = 10) de acordo com a fonte fotoativadora e momento de exposição à luz: I) Luz halógena (LH) com densidade de potência 600 mW/cm² + fotoativação imediata (t0); II) LH + fotoativação após 10 min (t10); III) LED com densidade de potência 800 mW/cm² (LED-800)+ t0; IV) LED-800 + t10; V) LED com densidade de potência 1.500 mW/cm² (LED-1500)+ t0; VI) LED-1500 + t10. Após a cimentação dos pinos, slicesdas regiões cervical, média e apical foram submetidos ao teste de push-out e avaliação das falhas. Verificou-se que LED-800 (4,40 ± 3,00 MPa) e LED-1500 (4,67 ± 3,04 MPa) proporcionaram resistência de união estatisticamente superior à LH (3,13 ± 1,76 MPa) (p<0,05), e não diferiram entre si (p>0,05).Não houve diferença estatisticamente significante da resistência de união entre t0 e t10 (p>0,05). A região cervical (4,75 ± 3,10 MPa) apresentou maiores valores de resistência de união que a apical (3,32 ± 2,30 MPa) (p<0,05) e a região média (4,14 ± 2,60 MPa) mostrou valores intermediários. Falhas adesivas foram predominantes no grupo LH, independentemente da região pino/canal. A parte apical apresentou predomínio de falhas adesivas e mistas. Concluiu-se que a resistência de união do cimento resinoso à dentina intrarradicular foi maior no terço cervical,com fotoativação com LED, independente do momentode exposição à luz.

Flexural properties, morphology and bond strength of fiber-reinforced posts: influence of post pretreatment

The aim of this study was to assess the influence of surface pretreatments of fiber-reinforced posts on flexural strength (FS), modulus of elasticity (ME) and morphology of these posts, as well as the bond strength (BS) between posts and core material. Fifty-two fiber posts (smooth and serrated) were assigned to 4 groups (n=13): no treatment (control), 10% hydrogen peroxide (HP) for 10 min (HP-10), 24% HP for 1 min (HP-24) and airborne-particle abrasion (Al2O3). To evaluate FS and ME, a 3-point bending test was performed. Three posts of each group were examined by scanning electron microscopy. Composite resin was used as the core build-up and samples were sectioned to obtain microtensile sticks. Data were analyzed by ANOVA and Tukey's test (α=0.05). For FS, significant differences were observed between posts type and surface pretreatment (p<0.05), with the highest means for the smooth posts. Al2O3 provided higher FS than HP-24. Al2O3 promoted higher ME than HP-24 and control. SEM images revealed partial dissolution of the resin matrix in all treated groups. The smooth posts had higher BS and FS than serrated posts (p<0.05). Mechanical properties of the glass fiber posts and the bond strength between posts and composite material were not altered by the surface treatments, except for airborne-particle abrasion that increased the post elastic modulus.

O objetivo deste estudo foi avaliar a influência do pré-tratamento de superfície dos pinos de fibra de vidro na resistência à flexão (RF), módulo de elasticidade (ME) e morfologia, bem como a resistência de união (RU) entre os pinos e o núcleo de preenchimento. Cinqüenta e dois pinos de fibra de vidro (lisos e serrilhados) foram divididos em 4 grupos (n=13): sem tratamento (controle), peróxido de hidrogênio a 10% por 10 min (HP-10), peróxido de hidrogênio 24% por 1 min (HP-24) e jato de óxido de alumínio (Al2O3). Para avaliar a RF e ME, o ensaio de flexão de 3 pontos foi realizado. Três pinos de cada grupo foram examinados em MEV. Resina composta foi utilizada como núcleo de preenchimento e as amostras foram seccionadas para obter palitos de microtração. Os dados foram analisados por ANOVA e teste de Tukey (α=0,05). Na RF, observou-se diferença estatisticamente significante entre os pinos e tipo de pré-tratamento de superfície (p<0,05), com as maiores médias para os pinos lisos. Al2O3 proporcionou maior RF que HP-24. Al2O3 promoveu maior ME que HP-24 e grupo controle. MEV revelou dissolução parcial da matriz de resina em todos os grupos tratados. Os pinos lisos tiveram a maior RU (p<0,05). Os pinos lisos apresentaram RF e RU superior aos pinos serrilhados (p<0,05). As propriedades mecânicas dos pinos de fibra de vidro e a resistência de união entre os pinos e o material resinoso não foram alterados pelos tratamentos de superfície, com exceção do jato de óxido de alumínio que aumentou o módulo de elasticidade dos pinos.

Microtensile bond strength of quartz fiber posts to different composite cores

The aim of this in vitro study was to assess the microtensile bond strength of quartz fiber posts to different composites, and to composite combinations used as core materials. Thirty fiber posts were treated with a 24 percent hydrogen peroxide solution and silanized. The posts were divided into 5 groups according to the resin composite used as follows (n = 6): G1 - Ælite Flow (Bisco, Inc), G2 - Filtek Z250 (3M ESPE), G3 - Biscore (Bisco, Inc), G4 - Ælite Flow + Filtek Z250, G5 - Ælite Flow + Biscore. The resin composites were placed around the posts to produce cylindrical specimens. Two 1-mm² thick sticks containing the post in the center and composite cores on both ends were provided from each cylinder and tested for microtensile strength with a crosshead speed of 0.5 mm/min. One-way ANOVA and Tukey HSD tests were used for statistical analysis. Fractured surfaces were observed using a stereomicroscope with 20× magnification. Scanning electron microscopy (SEM) was used to evaluate the interface of the fractured sticks. The results showed that G2 had the highest bond strength values, and the lowest values were seen with G3. There were significant differences between groups 1, 2, 4 and groups 3, 5 (p < 0.05). Under the stereomicroscope, most of the failures were adhesive between the post and core material. Under SEM, Ælite and Z250 had smoother surfaces than Biscore, containing less porosities and voids.

Influence of remaining coronal structure and finish line on the fracture strength of roots restored with metallic posts

The purpose of this study was to evaluate the fracture strength of roots that were prosthetically restored with metallic posts with or without any remaining coronal structure and with different finish lines. Sixty bovine incisors were sectioned below the cementoenamel junction, endodontically treated, and randomly divided into six experimental groups (n = 10) containing teeth with or without any remaining coronal structure, and with a beveled shoulder, a bevel, or a shoulder finish line design. The metallic posts were luted with dual-cured resin cement. The cores were made with composite resin, and metal crowns were cemented with zinc phosphate cement. The specimens were subjected to a tangential compressive load (135º angle) at a crosshead speed of 0.5 mm/min until failure, using a universal testing machine. The fracture strength data were analyzed using the ANOVA and LSMeans (least square means) tests (α= 0.05). The data indicated that the teeth with 2 mm of remaining coronal structure showed the highest fracture strength values when compared with the teeth without any remaining structure (p < 0.05). As to the different finish line designs, the highest fracture strength values were obtained for the beveled shoulder, followed by the bevel and then by the shoulder designs (p < 0.05). It may be concluded that, to increase fracture strength, a beveled shoulder and 2 mm of remaining coronal structure are the ideal conditions.

An interdisciplinary approach to reconstruct a fractured tooth under an intact all ceramic crown: Case report with four years follow up.

Trauma causing the fracture of a restored tooth with the extracoronal full coverage prosthesis remaining intact is a common occurrence in dental practice. Reconstruction of the damaged tooth foundation and recementation of the crown can pose quite a challenge for the restorative dentist. This case report describes an innovative interdisciplinary chairside technique for the recementation of an all-ceramic crown on a fractured maxillary central incisor. The course of care described is effective, affordable, and saves time in comparison with other treatment options for such clinical situations.