Facultad de Ciencias de la Salud

This in vitro study aimed to evaluate the effect of different bonding strategies on the microshear bond strength ( SBS) of luting agents to CAD–CAM composites. Surface scanning electron microscopy (SEM) and spectroscopy by energy-dispersive X-ray spectroscopy (EDS) were performed to analyze the surfaces of the composite before and after bonding treatment. Three CAD–CAM composites were evaluated: Lava Ultimate restorative (LU), Brava Blocks (BR), and Vita Enamic (VE). The LU and BR surfaces were sandblasted using aluminum oxide, while the VE surfaces were etched using a 5% hydrofluoric acid gel according to the manufacturers’ recommendations. All surfaces were subjected to the following bonding strategies (n = 15): adhesive with silane and MDP (ScotchBond Universal, 3M Oral Care, St Paul, MI, USA); adhesive with MDP (Ambar Universal, FGM, Joinville, Brazil); adhesive without silane or MDP (Prime&Bond Elect, Dentsply Sirona, Charlotte, NC, USA), pure silane without MDP (Angelus, Londrina, Brazil), and pure silane with MDP (Monobond N, Ivoclar Vivadent, Schaan, Liechtenstei). Afterwards, tygons were filled with RelyX Ultimate (3M Oral Care), AllCem (FGM), or Enforce (Dentsply Sirona), which were light-cured and subjected to the SBS test. Data were analyzed using two-way ANOVA and Bonferroni’s post hoc test ( = 0.05). Additional blocks (n = 15) were subjected to scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) before and after the surface treatment. The SBS values on VE surfaces were higher than those observed on LU and BR surfaces (p < 0.001). Silane without MDP (Allcem) promoted the highest SBS values, while silane with MDP (RelyX Ultimate) provided the highest values among all bonding strategies (p < 0.001). Enforce promoted no significant difference in SBS values. SEM and EDS analyses detected noticeable changes to the surface morphology and composition after the surface treatment. The effectiveness of the bonding strategy may vary according not only to the CAD–CAM composite but also to resin cement/bonding agent/silane used.

To evaluate the biomodification ability of lignin used as pre-treatment in human dentin before the application of an etch-and-rinse adhesive. Experimental hydroethanolic solutions with different cross-linking agents were used: 6.5% proanthocyanidins (PAC, from grape-seed extract); 2% cardanol (CARD, from cashew-nut shell liquid); lignin (LIG, from eucalyptus) at 1, 2 or 4% concentrations. The negative control (NC) was ethanol 50 v%. Extracted molars were prepared, and dentin microtensile bond strength ( TBS) was evaluated after 24 h water storage or 10,000 thermocycling aging. Further specimens were processed for SEM nanoleakage, micropermeability confocal microscopy evaluation and in situ degree of conversion (DC) through micro-Raman spectroscopy. Demineralized dentin sticks were submitted to a three-point bending test to evaluate the elastic modulus (E) before and after 1 min biomodification using the tested solutions. Moreover, it was also evaluated the mass changes and hydroxyproline (HYP) release after 4-weeks of water storage. Vibrational collagen crosslinking identification was evaluated through micro-Raman spectroscopy. The results were analyzed by analysis of variance (ANOVA) and Tukey’s test ( = 0.05). A significant reduction in TBS was observed in groups NC (p < 0.001) and CARD (p = 0.026). LIG-4% showed no significant reduction in TBS after aging (p = 0.022). Nanoleakage micrographs showed hybrid layer protection with all agents, but reduced micropermeability was attained only with lignin. Polymerization was negatively affected in the presence of all tested cross-linking agents, except LIG-1%. Lignin and cardanol increased the dentin E values, but only lignin reduced the mass loss in dentin specimens. Effective collagen crosslinking (1117 cm􀀀1 and 1235 cm􀀀1) was detected for all agents. HYP release was significantly lower with LIG-1% than NC (p < 0.001). Lignin was able to perform collagen cross-linking and prevent the degradation of unprotected dentin collagen, thereby improving the bonding performance of the composite restorations performed in this study.

Dental trauma may have a severe impact on the social and psychological wellbeing of a patient. Most cases of dental injuries involve anterior teeth, especially the maxillary upper incisors. Crown fractures, with or without pulp exposure, are the most common trauma in permanent dentition. There are many methods of management, in which the initial state of the pulp, the time since the injury, and the presence of an accompanying injury play a key role. This case report aimed at showing a possible conservative treatment after complicated tooth fracture that consisted of partial pulpotomy followed by adhesive reattachment of the tooth fragment using a technique based on heated resin composite. Such a specific procedure represents a conservative approach to traumatic coronal lesions, providing a suitable opportunity to maintain the tooth vitality, aesthetics, and function. Indeed, reattachment of tooth fragment using a composite/adhesive is a simple technique to achieve excellent results in terms of aesthetic and function.

The aim of the present study was to evaluate the influence of several experimental pretreatment crosslinker solutions on the resin polymer–dentine interface created using a representative universal adhesive system, by means of microtensile bond strength testing ( TBS), nanomechanical properties and ultramorphology confocal laser scanning microscopy (CLSM). Five experimental solutions containing different flavonoids were applied as dentine pretreatment after acid etching. A control pretreatment group containing no flavonoid was also employed. A representative modern universal adhesive was then applied, followed by a 3 mm thick composite built up. Specimens were sectioned into sticks and submitted to a TBS test or nanoindentation analysis along the interface (24 h or 25,000 thermocycles). The ultramorphology of the polymer–resin interface was also evaluated using CLSM. The results were analyzed using two-way ANOVA and Bonferroni’s post hoc test ( = 0.05). All flavonoids improved short- and long-term TBS values (p < 0.01), while only some specific such solutions improved the nanomechanical properties (p < 0.05) and preserved the structural morphology of the interface after aging. Pretreatment of acid-etched dentine using specific flavonoid-containing solutions may be a promising approach to improve both the nanomechanical properties and the durability of modern universal adhesive systems.

This study investigated the antibacterial activity, bond strength to dentin (SBS), and ultra-morphology of the polymer–dentin interface of experimental adhesive systems doped with pyrogallol (PY), which is a ubiquitous phenolic moiety that is present in flavonoids and polyphenols. A universal adhesive containing 4-META and 10-MDP was used in this study. PY behaves as an antioxidant and anti-cancerogenic agent and it was incorporated into the adhesive at different concentrations (0.5 and 1 wt.%). The antibacterial activity and SBS were analyzed and the results were statistically analyzed. The ultra-morphology of the polymer–dentin interface was assessed using scanning electron microscopy (SEM). At 24 h, a lower antibacterial activity was observed for the control adhesive compared to those with 0.5% and 1% PY. No difference was seen in SBS between the three groups at 24 h. After 6 months, the SBS of the 0.5% PY adhesive was significantly lower than the other tested adhesives. The specimens created with 1% PY adhesive presented a higher bond strength at six months compared with that found at 24 h. No morphological differences were found at the polymer–dentin interfaces of the tested adhesives. Pyrogallol may be incorporated into modern universal adhesive systems to preserve the polymer–dentin bonding interface and confer a certain degree of antibacterial activity.

This study evaluated the influence of an aqueous propolis-based solution (PROP) on gap formation and bond strength of posts bonded to root canal dentin using resin cements. Endodontically-treated bovine incisors received different irrigation protocols: 1) 2.5% sodium hypochlorite (NaOCl)/17% EDTA/NaOCl; 2) saline solution (NaCl)/EDTA/0.12% chlorhexidine (CHX); 3) NaOCl/PROP/ NaOCl; 4) NaCl/PROP/CHX; 5) NaCl/PROP/NaCl. Posts were then bonded with cements: RelyX ARC; Panavia F2.0; or RelyX U200 (n=10). The specimens were cross-sectioned. Gaps were assessed and performed the push-out bond strength test. Surface roughness of dentin fragments was also evaluated. Statistical analysis was performed (5%). RelyX U200 exhibited greater gap-free interfaces. Bond strength varied as a function of cements and irrigation protocols. PROP irrigation had no negative effect on the bond strength (p>0.05). Roughness increased significantly after NaOCl/EDTA/NaOCl, but remained unaltered after PROP irrigation protocols. Propolis-based irrigation protocols do not interfere in the bonding performance of posts cemented to root canal dentin.

La mejora en la resistencia adhesiva en dentina y la reducción de la degradación de la capa híbrida, que suele acontecer en los sistemas adhesivos simplificados, puede lograrse mediante la aplicación múltiple de capas adhesivas hidrófobas. Sin embargo, todavía existe cierta controversia sobre si con esta estrategia podemos mejorar o no la adhesión de los adhesivos universales de última generación, cuando se utilizan con la técnica de grabado total. Presentamos un estudio «in vitro», donde se evaluó una nueva técnica adhesiva simultánea utilizando un sistema adhesivo universal autopolimerizable junto a un composite fluido. Se utilizaron veinte terceros molares sanos extraídos. Los dientes se dividieron aleatoriamente en dos grupos, según la aplicación del adhesivo (n = 10): Grupo A: aplicación por instrucciones del fabricante [CTR]; Grupo B: aplicación adhesiva simultánea del adhesivo junto a un composite ultrafluido [ADS]. Toda la muestra se almacenó durante 24 horas y se seccionó para obtener especímenes/barritas con un grosor de ≈ 1mm2. El 50% (barritas) se asignó a la evaluación de la fuerza de microtracción (μTBS) inmediata, y el otro 50% se almacenó en saliva artificial durante 8 meses. Se realizó un análisis fractográfico con microscopio electrónico de barrido (MEB) e igualmente se prepararon 3 dientes más por grupo para un análisis bajo microscopía confocal. Los resultados obtenidos se pueden clasificar en: - Microtensión: la técnica de adhesión simultánea [ADS] ofreció valores más elevados y menor pérdida de fuerza adhesiva con el envejecimiento que la técnica convencional [CTR]. La reducción de la fuerza adhesiva en el grupo CTR fue estadísticamente significativa (p<0,05), la del grupo ADS no (p>0,05). - Microscopía electrónica de barrido: el grupo A [CTR] presenta una infiltración parcial del colágeno a las 24 horas y una degradación total de la matriz resinosa a 8 meses con tags de resina expuestos. El grupo B [ADS], por el contrario, presentaba una dentina totalmente recubierta y protegida por resina a 24 horas. A ocho meses, solo se observó una degradación parcial en la matriz resinosa. - Microscopía confocal: el grupo A [CTR] reveló a 8 meses un aumento de la micropermeabilidad caracterizada por la presencia de degradación y gaps. En el grupo B [ADS], observamos únicamente un aumento de la permeabilidad con el envejecimiento, pero en una interfaz dentina-adhesivo totalmente íntegra y sin evidencia de degradación y gaps. La técnica de adhesión simultánea podría tener un efecto favorable sobre la adhesión inmediata y a largo plazo de nuestras restauraciones, mejorando la práctica diaria de la Odontología Restauradora Adhesiva.

Purpose: The aim of this study was to evaluate the chemomechanical properties, antibacterial activity, and cytotoxicity of an experimental adhesive resin containing halloysite nanotubes (HNT), doped with alkyl trimethyl ammonium bromide (ATAB). Materials and Methods: A filler of HNT doped with ATAB was obtained (ATAB:HNT) and incorporated (5 wt%) into a resin blend made of bisphenol A glycerolate dimethacrylate, 2-hydroxyethyl methacrylate and a photoinitiator/co-initiator system (GATAB:HNT). The same resin blend without ATAB:HNT was used as control (Ctrl). The ATAB:HNT filler was assessed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The two tested adhesives were evaluated for degree of conversion (DC) in vitro and in situ, softening in alcohol, dentin microtensile bond strength (μTBS), antibacterial activity, and cytotoxicity (n = 5). Results: SEM showed that the nanotubes had a characteristic tubular-needle morphology, while the TEM analysis confirmed the presence of ATAB inside the lumens of HNT. The incorporation of ATAB:HNT induced no reduction (p > 0.05) of the DC either in situ or in vitro. No difference was encountered after the softening challenge test (p > 0.05) and no difference was found in μTBS between the two adhesives, both at 24 h (p > 0.05) and after 6 months of storage in distilled water (p > 0.05). However, ATAB:HNT reduced Streptococcus mutans viability (p < 0.05) without a cytotoxic effect on pulp cells (p > 0.05). Conclusions: GATAB:HNT adhesive demonstrated appropriate polymerization without significant differences in softening after solvent immersion, while concomitantly maintaining reliable bond strength after 6 months of water aging. Moreover, the ATAB:HNT filler can provide antibacterial activity to the adhesive resin without affecting pulp cell viability.

Introduction: This study compared bacterial percolation and sealer penetration of a novel obturation technique with the ones of warm vertical condensation technique. Methods and Materials: A bacterial percolation test was carried out with 80 single rooted human teeth divided into 5 groups; A (n=20): warm vertical condensation and AH-Plus, B (n=20): CPoint with AH-Plus, C (n= 20): CPoint with EndoSequence BC, +ve Control (n=10): teeth with no canal obturation, -ve Control (n=10): teeth with no access cavity. The samples were inoculated with a multispecies bacterial incoulum. Bacterial percolation was evaluated by turbidity. Confocal laser scanning microscopy (CLSM) was used to observe the presence of gaps and voids. Further 48 extracted human mandibular single-canal premolars were used to determine the sealer penetration. Slices of the samples were observed by CLSM to evaluate tubules penetration of the sealer. Kaplan Meyer survival, ANOVA one way and Tuckey HSD test and a Wilcoxon signed-rank test were utilised. Results: A Kaplan-Meier test showed no significant difference overall (P>0.05) between groups A, B and C. At 43 days, the group B showed a significantly inferior ability to prevent bacterial passage (P<0.05). The group C showed a deeper sealer penetration than group A and B with statistically significant differences (P<0.05) for the total penetration (ANOVA one way and Tukey HSD). A Wilcoxon signed-rank test showed statistically significant differences for the penetration in the middle-and apical third of the 3 groups. Conclusion: Based on this in vitro study, the single polymer-cone obturation technique with a resin based- and bioceramic based-sealer behaved similarly to the warm vertical obturation technique in preventing bacterial passage. The bioceramic sealer showed the deepest penetration but did not fully prevent bacterial leakage.