Influence of Battery Levels in Cordless LED Light-curing Units on Properties of Resin Cement and Glass Fiber Post Retention.

PURPOSE: This study aimed to assess the impact of battery levels in single-peak and multi-peak light-curing units (LCUs) on irradiance, and their effects on glass fiber post push-out bond strength to root dentin and the degree of conversion of dual-cure universal resin cement. METHODS AND MATERIALS: Sixty bovine roots underwent endodontic treatment and were randomly distributed into 6 groups (n=10), formed by combining two LCUs (single-peak and multipeak) and three battery levels (100%, 50%, and 10%). A spectrophotometer measured irradiance (mW/ cm2) and spectral irradiance (mW/cm2/nm). Push-out bond strength (PBS) tests occurred at three root regions (cervical, middle, and apical), with optical and scanning electron microscopy for failure mode analysis. Degree of conversion (DC) was evaluated across the root regions. Data were analyzed using two-way repeated measures ANOVA and the Tukey HSD test. The Fisher exact test verified failure modes (α=0.05). RESULTS: As multipeak LCU battery levels decreased, emitted irradiance also diminished, with notable PBS reductions in the apical thirds. Failure modes were influenced by different conditions, primarily exhibiting mixed modes. Battery levels significantly impacted DC in the multipeak LCU, particularly in the cervical region, while the single-peak LCU exhibited DC reduction at the 10% battery level in the cervical region. CONCLUSIONS: Emitted irradiance, resin cement DC, and glass fiber post bond strength to root dentin may be influenced by varying cordless LCUs and battery levels.

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.

Evaluation of Intra Root Canal Er,Cr:YSGG Laser Irradiation on Prosthetic Post Adherence.

PURPOSE: In clinical prosthetics procedures, including endodontics and post fixation, the presence of a smear layer can reduce the post bond strength. An Er,Cr:YSGG laser, which emits at 2780 nm, can promote a smear-layer-free surface due to the ablation process. Considering these aspects, the purpose of this work was to evaluate the influence of Er,Cr:YSGG laser irradiation using either a radial or an axial fiber tip on the bond strength of three resin cements to the fiber-reinforced composite posts. MATERIALS AND METHODS: Ninety recently extracted single rooted human teeth had their root canal instrumented and were randomly distributed into nine experimental groups, in which three resin cements (total-etching Variolink II, self-etching Panavia F, and self-adhesive RelyX Unicem Aplicap) and three root canal treatments (no treatment, laser irradiation using the radial fiber tip, laser irradiation using the axial fiber tip) were used. Specimens were then sectioned into three sections (cervical, middle, and apical thirds) with two slices on each section. A push-out test was performed on each slice, and the values were recorded as MPa. The push-out data were analyzed by a Ryan-Joiner normality test followed by a two-way ANOVA test and Tukey pairwise comparison. The statistical analysis was performed on each third section separately, with a 5% significance level. RESULTS: Laser irradiation with axial fiber tip significantly increased the post bond strength of RelyX Unicem Aplicap on middle third of specimens (p < 0.001) when compared to other root canal treatments (unlased or irradiated with radial tip). Considering the Panavia resin cement, laser irradiation with either axial or radial tips promoted a significant increase on the post bond strength of middle third when compared to unlased specimens (p < 0.001); however, laser irradiation did not influence the post bond strength of Variolink resin cement. CONCLUSIONS: The use of the Er,Cr:YSGG laser for clinical prosthetics procedures enhances the post bond strength of Panavia and RelyX Unicem Aplicap resin cements, mainly at middle third of roots, and does not interfere with the bond strength of Variolink resin cement. For the RelyX Unicem Aplicap system, the use of axial tip is most advantageous and can be recommended for future clinical application.

The Influence of Post System Design and Material on the Biomechanical Behavior of Teeth with Little Remaining Coronal Structure.

PURPOSE: To evaluate the influence of different post systems on the biomechanical behavior of teeth with a severe loss of remaining coronal structure. MATERIALS AND METHODS: Fifty standardized bovine teeth (n = 10 per group) were restored with: cast post-and-core (CPC), prefabricated metallic post (PFM), parallel glass-fiber post (P-FP), conical glass-fiber post (C-FP), or composite core (no post, CC). The survival rate during thermomechanical challenging (TC), the fracture strength (FS), and failure patterns (FP) were evaluated. Finite element models evaluated the stress distribution after the application of 100 N. RESULTS: All specimens survived TC. Similar FS was observed among post-containing groups. Groups P-FP and CC presented 100% repairable fractures. The von Mises analysis showed the maximum stresses into the root canal in groups restored with metallic posts. Glass-fiber posts and CC presented the maximum stresses at the load contact point. Glass-fiber groups showed lower stresses in the analysis of maximal contact pressure; CPC led to the highest values of contact pressure. The modified von Mises (mvM) stress in dentin did not show differences among groups. Moreover, mvM values did not reach the dentin fracture limit for any group. CONCLUSIONS: The type of intracanal post had a relevant influence on the biomechanical behavior of teeth with little remaining coronal structure.

Influence of light transmission through fiber posts: Quantitative analysis, microhardness, and on bond strength of a resin cement.

CONTEXT: Light transmission (LT) into deeper areas of the dentin root is limited. AIM: The aim of this study is to perform a quantitative investigation of the radial transmission of light (LT) through different fiber posts and its influence on the Knoop hardness number (KHN) and bond strength (BS) of a dual-cure self-adhesive resin cement at 3 different depths. MATERIALS AND METHODS: Four types of fiber posts (2 translucent and 2 conventional) were used. LT and KHN analyses were performed in a specially designed matrix, which allowed measurements at 3 different depths. LT was measured using a volt-ampere meter while KHN tests were performed in a microhardness tester. For BS analysis, endodontically treated bovine roots were divided into 4 groups, each group receiving one type of post. After cementation, cross sections of the root were tested for resistance to displacement using a universal testing machine. STATISTICAL ANALYSIS USED:: Statistical analysis was performed by using this ANOVA and Tukey's test. RESULTS: For LT, translucent posts showed significantly higher values at all depths compared to the conventional ones. For all posts, LT decreased at the deeper depths. The KHN results showed no statistical differences among the different posts, regardless of depth. For BS, a translucent post showed the highest values, and comparative analyses between the different depths of posts also showed statistically significant differences while comparisons among the different depths of the same post showed no differences. CONCLUSIONS: LT depended on the type of post and on depth. The type of post did not significantly influence the cement KHN. A translucent post showed higher BS in pooled data.

Effect of CAD/CAM glass fiber post-core on cement micromorphology and fracture resistance of endodontically treated roots.

PURPOSE: To investigate the fracture resistance of weakened roots restored with prefabricated or CAD/CAM-customized posts and cores as well as the thickness of the cement film and the presence of voids in the cement. METHODS: The roots of 40 human premolars were weakened by removing internal dentin with a diamond bur (2.5 mm in the coronal third and 1.5 mm in the apical third) and restored with prefabricated posts (PPs) or customized posts (CPs) with or without a zirconia crown (n= 10). Posts and crowns were cemented with resin cement. Microtomography was used to determine the thickness of the cement film and whether voids were present. After fatigue testing (1 million cycles, 50 N, 5 Hz, 36.5°C), the specimens underwent compression testing with an oblique load (30°, 1 mm/minute) and fracture strengths were recorded (N). Fracture strength and film thickness were analyzed with ANOVA and the Games-Howell test; the variable presence of voids was analyzed with the Mann-Whitney test (α= 5%). RESULTS: Mean fracture strengths varied between 640.4 and 792.9 N and did not differ significantly between groups. The CP group had a thinner cement film and fewer voids than the PP group. There was a positive, statistically significant correlation (Spearman, R=0.488, P= 0.029) between these variables. CLINICAL SIGNIFICANCE: CAD/CAM-manufactured glass-fiber posts and cores do not affect the fracture strength of flared root canals or cause catastrophic failure of the root when used with zirconia crowns.

Desadaptação apical e cervical de núcleo metálico fundido em função do material e da técnica de moldagem indireta / Apical and cervical maladaptation of cast metal core due to the used material and the indirect impression technique

Avaliou-se, microscopicamente, a desadaptação cervical e, radiograficamente, a desadaptação apical de núcleos metálicos fundidos (NMFs) moldados com silicone de condensação e adição, comparando a utilização ou não de suporte intrarradicular. Por meio do corpo mestre foram obtidos 40 moldes divididos em quatro grupos: Silicone de condensação com suporte intrarradicular, Silicone de condensação sem suporte, Silicone de adição com suporte e Silicone de adição sem suporte. Sobre os modelos foram modelados pinos em resina Dencrilay e fundidos com liga de cobalto-cromo. A desadaptação cervical foi medida com microscópio comparador de dupla coordenada digital (30x). A desadaptação apical foi medida a partir de 40 radiografias digitais e análise em software, através da distância entre o ponto mais apical do núcleo até o início do material obturador. Pelo coeficiente de correlação intraclasse, o comprimento da porção intrarradicular do NMF ficou aquém do comprimento real do conduto para os quatro grupos estudados. A análise de variância e o teste de Tukey aplicados aos dados de desadaptação cervical revelaram que as técnicas com e sem suporte não diferiram entre si, quando usado silicone de condensação. Com o silicone de adição, a técnica com suporte ocasionou a maior desadaptação cervical. Quanto à região apical, constatou-se que a desadaptação não foi afetada pela utilização de suporte intrarradicular (p = 0,651), pelo material de moldagem (p = 0,322), nem pela interação de ambos (p = 0,180). Concluiu-se que a utilização de suporte intrarradicular durante a moldagem para a confecção de NMF para ambos os silicones torna-se dispensável (AU).

This study evaluated microscopically and radiographically, the cervical and apical maladaptation of cast metal cores obtained from molds with silicone polymerized by condensation and addition, comparing the need to use intra-radicular support. Through the master body, 40 molds were obtained and divided into four groups: Condensing silicon with, Condensing silicon without support, Silicone addition with support, and Silicone addition without support. The models were modeled in Dencrilay resin and cast with cobalt-chromium alloy. Cervical maladaptation was measured with double digital coordinate comparator microscope (30x). The apical maladaptation was measured from 40 digital radiographs and software analysis, through the gap between the most apical point of the core and the beginning of the filling material. According to the intraclass correlation coefficient, the length of the intra-radicular portion of the cast metal cores was below the actual length of the conduit for the four groups studied. The analysis of variance and Tukey's test applied to the data of cervical maladaptation revealed that the techniques with and without support did not differ from each other when using condensation silicone. With addition silicone, the technique with support caused most cervical maladjustment. As for the apical region, it was found that the maladaptation was not affected by the use of intra-radicular support (p = 0.651), by the molding material (p = 0.322) or by the interaction of both (p = 0.180). It was concluded that intra-radicular support during molding for the manufacture of cast metal cores, for both silicones, becomes dispensable (AU).

Randomized clinical trial of the influence of impression technique on the fabrication of cast metal posts.

STATEMENT OF PROBLEM: Direct and indirect techniques are used for intracanal impression and fabrication of cast metal posts. However, whether those techniques affect the accuracy of cast metal posts is unknown. PURPOSE: The purpose of this randomized clinical trial was to evaluate the accuracy of cast metal posts depending on tooth position and impression technique. MATERIAL AND METHODS: Endodontically treated teeth (anterior or posterior) planned to receive cast metal posts and complete crowns were randomized according to impression technique (direct or indirect). Impressions were made by 2 operators, and time for the impression was recorded. All impressions and cast metal posts were photographed to assess any possible differences between techniques in length of the cast metal post. RESULTS: All cast metal posts were shorter than the impressions. The mean reduction for the metal posts was 2.3% for direct in anterior teeth, 5.7% for direct in posterior teeth, 6.3% for indirect in anterior teeth, and 7.2% for indirect in posterior teeth (all P<.05). Statistically significant differences were found between time of technique and tooth position (P=.031), with the direct technique more time consuming than the indirect technique (P<.001) for both tooth positions. For the indirect technique, the impression times for both tooth groups were similar (P=.459). CONCLUSIONS: Both of the intracanal impression techniques resulted in cast posts that were shorter than the impressed post space. The discrepancy was greatest for the indirect technique. Nevertheless, all posts were considered clinically acceptable and were cemented.

Effect of Instrumentation Techniques, Irrigant Solutions and Artificial accelerated Aging on Fiberglass Post Bond Strength to Intraradicular Dentin.

OBJECTIVE: To evaluate the effect of instrumentation techniques, irrigant solutions and specimen aging on fiberglass posts bond strength to intraradicular dentine. MATERIALS AND METHODS: A total of 120 bovine teeth were prepared and randomized into control and experimental groups resulting from three study factors (instrumentation techniques, irrigant solutions, specimen aging). Posts were cemented with RelyX U100. Samples were submitted to push-out test and failure mode was evaluated under a confocal microscope. RESULTS: In specimens submitted to water artificial aging, nickel-titanium rotary instruments group presented higher bond strength values in apical third irrigated with NaOCl or chlorhexi-dine. Irrigation with NaOCl resulted in higher bond strength than ozonated water. Artificial aging resulted in significant bond strength increase. Adhesive cement-dentin failure was prevalent in all the groups. CONCLUSION: Root canal preparation with NiTi instruments associated with NaOCl irrigation and ethylenediaminetetra acetic acid (EDTA) increased bond strength of fiberglass posts cemented with self-adhesive resin cement to intraradicular dentine. Water artificial aging significantly increased post-Clinical significance: The understanding of factors that may influence the optimal bond between post-cement and cement-dentin are essential to the success of endodontically treated tooth 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.

Effect of two resin cements and two fiber post surface treatments on push-out bond strength between fiber post and root dentin.

AIM: To evaluate the effect of fiber post surface treatments on push-out bond strength between fiber post and root dentin. MATERIALS AND METHODS: Sixty bovine mandibular teeth (N=60) were sectioned (16 mm), prepared (12 mm), embedded with acrylic resin and then allocated into six groups (n=10): Gr1- Silane coupling agent (Sil)+Conventional resin cement AllC em (Al C); Gr2- Sil+Conventional resin cement RelyX ARC (ARC); Gr3- tribochemical silica coating (TBS)+AlC; Gr4- TBS+ARC; Gr5- No treatment (NT)+AlC; Gr6- NT+ ARC. Specimens were sectioned in four slices (2 mm) and submitted to push-out test. Fracture analyses were executed at x200. The values of the push-out bond strength were submitted to two-way ANOVA and Tukey test (α=0.05). RESULTS: Resincement did not affect the bond strength values (p=0.9674), fiber post surface treatment affected the push-out bond strength (p=0.0353), interaction between factors did not affected the values (p=0.338). Tukey test did not show differences between the groups. Adhesive failure between cement and dentin was predominantly. CONCLUSION: The fiber post surface treatment appears have no Influence on bond strength between fiber post and root dentin. CLINICAL SIGNIFICANCE: The tested fiber posts surface treatment appears do not Influence the fiber post bond behavior.

The Effect of Self-adhesive and Self-etching Resin Cements on the Bond Strength of Nonmetallic Posts in Different Root Thirds.

PURPOSE: The purpose of this study was to evaluate the effect of self-adhesive and self-etching resin cements on the bond strength of nonmetallic posts in different root regions. MATERIALS AND METHODS: Sixty single-rooted human teeth were decoronated, endodontically treated, post-space prepared, and divided into six groups. Glass-fiber (GF) posts (Exacto, Angelus) and fiber-reinforced composite (FRC) posts (EverStick, StickTeck) were cemented with self-adhesive resin cement (Breeze) (SA) (Pentral Clinical) and self-etching resin cement (Panavia-F) (SE) (Kuraray). Six 1-mm-thick rods were obtained from the cervical (C), middle (M), and apical (A) regions of the roots. The specimens were then subjected to microtensile testing in a special machine (BISCO; Schaumburg, IL, USA) at a crosshead speed of 0.5 mm/min. Microtensile bond strength data were analyzed with two-way ANOVA and Tukey's tests. RESULTS: Means (and SD) of the MPa were: GF/SA/C: 14.32 (2.84), GF/SA/M: 10.69 (2.72), GF/SA/A: 6.77 (2.17), GF/SE/C: 11.56 (4.13), GF/SE/M: 6.49 (2.54), GF/SE/A: 3.60 (1.29), FRC/SA/C: 16.89 (2.66), FRC/SA/M: 13.18 (2.19), FRC/SA/A: 8.45 (1.77), FRC/SE/C: 13.69 (3.26), FRC/SE/M: 9.58 (2.23), FRC/SE/A: 5.62 (2.12). The difference among the regions was statistically significant for all groups (p < 0.05). The self-adhesive resin cement showed better results than the self-etching resin cement when compared to each post (p < 0.05). No statistically significant differences in bond strengths of the resin cements when comparable to each post (p > 0.05). CONCLUSION: The bond strength values were significantly affected by the resin cement and the highest values were found for self-adhesive resin cement.

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.

Influence of the artefact reduction algorithm of Picasso Trio CBCT system on the diagnosis of vertical root fractures in teeth with metal posts.

OBJECTIVES: To assess the influence of the artefact reduction algorithm (AR) available on the Picasso Trio 3D(®) imaging system (Vatech, Hwaseong, Republic of Korea) on image quality [greyscale values, contrast-to-noise ratio (CNR) and artefact formation] and diagnosis of vertical root fractures (VRFs) in the teeth with intracanal metal posts. METHODS: 30 uniradicular teeth had their crowns removed and their roots endodontically treated to receive intracanal metal posts. In 20 teeth, both complete (n = 10) and incomplete (n = 10) VRFs were created. Each tooth was scanned twice, with and without AR activation. The mean and variation of greyscale values, as well as CNR, were calculated for all images. Subsequently, an evaluator compared the amount of artefact (cupping, white streaks and dark bands) in all images. Five evaluators rated for VRF presence using a five-point scale. RESULTS: Mean greyscale values and CNR were significantly decreased in images acquired with the AR. The usage of the algorithm promoted an overall reduction of image artefacts. Regarding the diagnosis of complete and incomplete VRFs, the use of the AR had an overall negative impact on specificity and accuracy. CONCLUSIONS: While indeed reducing artefact formation, the use of the AR, instead of improving the impact on the diagnosis of VRFs in teeth with intracanal metal posts, had a negative impact on the diagnosis.

Mechanical properties of components of the bonding interface in different regions of radicular dentin surfaces.

STATEMENT OF PROBLEM: The mechanical properties of the adhesive materials used in intraradicular treatments could vary according to the interaction between the restorative material and dentin substrate. An evaluation of these properties is essential to determine the success of the luting procedures performed on glass-fiber posts. PURPOSE: The purpose of this study was to evaluate the mechanical properties of dentin adhesives, resin cements, and the dentin that underlies the bonding interface in different thirds of intraradicular dentin. MATERIAL AND METHODS: Forty extracted, single-rooted human teeth were used in this study. After the endodontic treatment of the post spaces, the teeth were divided into 5 groups (n=8): Adper Single Bond 2 + RelyX ARC, Excite DSC + RelyX ARC, Adper SE Plus + RelyX ARC, RelyX Unicem, and Set. The hardness and elastic modulus values were measured at the adhesive interface in different thirds of the radicular dentin by using an ultramicrohardness tester. The data were subjected to 2-way ANOVA and the Fisher protected least significant difference test (α=.05). RESULTS: In the underlying dentin, the highest Martens hardness values were found in the apical region for all groups; the exceptions were the groups with the self-etching adhesive. In the adhesive layer, the highest Martens hardness values were obtained for the Adper SE Plus + RelyX ARC group; further, no statistical differences were found among the different regions for this group. RelyX ARC had the lowest Martens hardness and elastic modulus values in the apical regions when used with Adper Single Bond 2 and Adper SE Plus. No differences were found in the Martens hardness and elastic modulus values for the self-adhesive resin cement in the regions investigated. CONCLUSION: The mechanical properties of adhesive materials and the underlying dentin are influenced by the interaction between the two as well as by the depth of the analyzed intraradicular area.

Efficiency and effectiveness evaluation of three glass fiber post removal techniques using dental structure wear assessment method.

AIM: This study evaluated the efficiency and effectiveness of three glass fiber post removal techniques. MATERIALS AND METHODS: Forty-five extracted maxillary teeth were endodontically treated and cross-sectioned in thirds. Presence of cementing agent and dental structure wear were assessed by analyzing images taken before luting of glass fiber post and after removal procedure. Teeth were divided into 3 groups: Group 1 - diamond bur + Largo reamer; Group 2 - ultrasonic insert; Group 3 - carbide bur + ultrasonic insert. Time spent on removal procedures, dental structure wear and amount of remaining cement agent were recorded and results submitted to ANOVA, Kruskal Wallis and Tukey-Kramer tests. RESULTS: Group 1 - 16'46", 33.33% and 6.99%; Group 2 - 12'31", 40% and 7.86%; and Group 3 - 10'24", 80% and 8.14%. Group 3 presented the most effective removal of glass fiber posts. CONCLUSION: There was no significant difference in efficiency among the evaluated techniques.

Influence of cone-beam computed tomographic scan mode for detection of horizontal root fracture.

INTRODUCTION: The purpose of the present study was (1) to test the accuracy of a small-volume cone-beam computed tomographic (CBCT) device in detecting horizontal root fractures (HRFs) in teeth with and without an intracanal metallic post (IMP) and (2) to investigate the use of 2 different acquisition protocols of a CBCT device for HRF diagnosis. METHODS: Forty endodontically treated teeth with and without an IMP were examined using PreXion 3D CBCT scanner (Terarecon, San Mateo, CA) with a 5-cm high and 5-cm diameter cylinder at 0.10-mm voxel reconstruction. Two observers analyzed the samples to determine the presence and location of HRFs. RESULTS: Sensitivity values ranged from 0.40-0.80. The most favorable results were found for the samples with no IMP observed using the protocol of a higher number of x-ray projections (0.70-0.80). Accuracy in the groups with an IMP ranged from 75%-90% in the 1024 x-ray projection protocol (HI-HI group) versus 70%-85% for the same samples examined in the 512 x-ray projection protocol (HI-STD group). Intraobserver agreement ranged from relevant to perfect concordance for both protocols (HI-HI = Kappa: 0.60-1.00 and HI-STD = Kappa: 0.55-0.89). Interobserver agreement ranged from moderate to perfect concordance for both protocols (HI-HI = Kappa: 0.79-0.89 and HI-STD = Kappa: 0.42-0.76). CONCLUSIONS: Even though there are statistically significant differences for the protocol with the higher number of x-ray projections, we found high accuracy, sensitivity, sensibility, and intra- and interobserver agreement in detecting HRFs for both Prexion 3D protocols.

Effects of sonic application of adhesive systems on bonding fiber posts to root canals.

INTRODUCTION: Luting posts inside the root canal is still a challenge because of the difficulty of bonding adhesive materials in the apical third of roots. This study evaluated the effect of the application mode of 3 simplified etch-and-rinse adhesives on the push-out bond strength (PBS), nanoleakage (NL), and in situ degree of conversion (DC) of fiber posts in the root canal. METHODS: The roots of human premolars were endodontically prepared and divided into 6 groups according to the combination of the main factors: adhesive (Ambar, FGM, Joinville, SC, Brazil; Adper Single Bond 2, 3MESPE, St Paul, MN; and XP Bond+self-cure activator, DeTrey Dentsply, Konstanz, Germany) and application mode (manual or sonic). The posts were cemented and the PBS tested at 0.5 mm/min. The NL was evaluated by scanning electron microscopy after the immersion of specimens in 50% silver nitrate. Micro-Raman spectroscopy was used to measure the in situ DC. Root third was also considered in the statistical evaluation. Data were analyzed by 3-way repeated measures analysis of variance and Tukey tests (5%). RESULTS: Under sonic application, the PBS and the in situ DC increased, whereas NL decreased significantly for all groups in the middle and apical thirds (P < .05). CONCLUSIONS: The application of simplified adhesives by sonic mode in the root canal is a feasible tool to increase the fiber post bond to root canals.

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.