Dpto. Odontología

This narrative review will focus on a number of contemporary considerations relating to the restoration of root filled teeth and future directions for research. Clinicians are now more than ever, aware of the interdependence of the endodontic and restorative aspects of managing root filled teeth, and how these aspects of treatment are fundamental to obtaining the best long-term survival. To obtain the optimal outcomes for patients, clinicians carrying out endodontic treatment should have a vested interest in the restorative phase of the treatment process, as well as an appreciation for the structural and biomechanical effects of endodontic-restorative procedures on restoration and tooth longevity. Furthermore, the currently available research, largely lacks appreciation of occlusal factors in the longevity of root filled teeth, despite surrogate outcomes demonstrating the considerable influence this variable has. Controversies regarding the clinical relevance of minimally invasive endodontic and restorative concepts are largely unanswered with respect to clinical data, and it is therefore, all too easy to dismiss these ideas due to the lack of scientific evidence. However, conceptually, minimally invasive endodontic-restorative philosophies appear to be valid, and therefore, in the pursuit of improved clinical outcomes, it is important that the efficacies of these treatment protocols are determined. Alongside an increased awareness of the preservation of tooth structure, developments in adhesive bonding, ceramic materials and the inevitable integration of digital dentistry, there is also a need to evaluate the efficacy of new treatment philosophies and techniques with well-designed prospective clinical studies.

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.

Minimally invasive (MI) concepts in restorative dentistry in the year 2020 request from the practitioner, not only a scientifically supported rational for carious tissue removal/excavation and defect-oriented, biological cavity preparation, but also a deep understanding of how to ensure a biomechanically stable and durable restoration in different clinical situations by applying different restorative options. Bio-reactive materials play an increasingly relevant role, as they not only replace diseased or lost tissue but also optimise tissue mineral recovery (among other properties) when used in restorative and preventive dentistry. Indeed, this is of certain interest in MI restorative dentistry, especially in those cases where gap formation jeopardises the integrity of the margins along resin composite restorations, causing penetration of bacteria and eventually promoting the formation of secondary caries. Recently, the interest on whether ion-releasing materials may reduce such biofilm penetration into margin gaps and reduce such a risk for development and propagation of secondary caries is growing significantly among clinicians and scientists. The aim of this article was to explore mechanisms involved in the process that allow mineral deposition at the interface between such materials and dentine and describe how conventional “bioactive” restorative materials currently available on the market may beneficial treatments in MI Dentistry.

Background: The objective was to evaluate the e ciency of ProTaper Gold (PTG) and Reciproc Blue (RB) NiTi files in obturation material removal from straight root canals assessed by micro-computed tomography. Methods: Fifty-two anterior human teeth were shaped with a PTG rotary system until F2 (25/.08). Specimens were obturated with a continuous wave of condensation technique. For retreatment, specimens were randomly distributed in two experimental groups: PTG group (F4 file) and RB (R40 file). Micro-CT scans were performed before and after retreatment procedures. The percentage of the remaining obturation material compared to the original volume was calculated, as well as the retreatment time. The presence of separated files was recorded. A descriptive analysis was carried out, and nonparametric tests were employed. Results: The mean percentages of remaining obturation material in the PTG group and the RB group were 4.14 4.30% and 4.18 4.29%, respectively. The mean retreatment times for the PTG and RB groups were 144 51 and 163 88 s, respectively. There were no statistically significant di erences, neither in removal e ciency (p > 0.05) nor in retreatment time (p > 0.05), between the two groups. The coronal and middle thirds presented significantly more remaining obturation material than the apical third (p < 0.05). No file separation occurred. Conclusions: ProTaper Gold and Reciproc Blue present with comparable e ciency in removing the obturation material, with a similar mean retreatment time.

To investigate the influence of pre-endodontic coronal wall restoration on smear layer removal during di erent root canal irrigation strategies, single-root premolars were prepared with a mesio-occlusal cavity. Half were left untreated (G1), while the mesial walls of the remaining half were reconstructed using a resin composite (G2). The specimens were divided into control (ctrl) groups, which used the conventional needle irrigation method, and four experimental subgroups according to irrigation strategy: Sonic activation using the Endoactivator, sonic activation using the EQ-S, mechanical activation using the XP-Endo finisher, and ultrasonic activation using the EndoUltra. Smear layer removal was assessed through SEM and the results were statistically analyzed. At the coronal and middle thirds, no significant di erence (p > 0.05) was detected for G1 and G2, except for the control subgroups (G1ctrl vs G2 ctrl) at the middle third. At the apical third, the smear layer removal was significantly greater for G2 than G1. In G1, both at the middle and apical level, EQ-S and EndoUltra showed greater smear layer removal (p < 0.05) compared to the others G1 subgroups. In G2, at the apical level, the EQ-S and EndoUltra were the most e ective in smear layer removal. Pre-endodontic coronal wall restoration may improve the smear layer removal during root canal irrigation.

The aim of the present study was to formulate dental adhesives with di erent concentrations of LiNbO3 and to evaluate their physicochemical and antibacterial properties. A dental adhesive was formulated using methacrylate monomers and photoinitiators and used as a control filler-free group. Subsequently, three experimental adhesives doped with LiNbO3 at di erent concentrations (1 wt.%, 2 wt.%, and 5 wt.%) were also formulated. All the experimental adhesives were assessed to evaluate the degree of conversion (DC), softening in solvent, immediate and long-term microtensile bond-strength ( -TBS), radiopacity, ultimate tensile strength, and antibacterial activity. The incorporation of 1 wt.% of LiNbO3 had no negative e ect on the DC of the adhesive resin compared to the control group (p > 0.05). We observed a decrease in the percentage of softening in solvent in the group LiNbO3 at 1 wt.% (p < 0.05). The addition of LiNbO3 increased the radiopacity at a concentration above 2 wt.%, and there was also an increase in cohesive strength (p < 0.05). The immediate -TBS increased for LiNbO3 at 5 wt.% (p < 0.05), and there was no statistical di erence for the other groups compared to the control (p > 0.05). After six months, the group with 5 wt.% still presented the highest -TBS (p < 0.05). The adhesives showed no antimicrobial activity (p > 0.05). LiNbO3 was successfully incorporated in dental adhesives, increasing the radiopacity and their resistance to degradation. Although LiNbO3 o ered no antibacterial properties, the reliability of LiNbO3 incorporation in the adhesive encourages new tests to better investigate the antimicrobial action of LiNbO3 through temperature variation.

The aim of this study is to analyze and compare the e cacy of three non-surgical endodontic retreatment techniques in removing a carrier-based root canal filling material from straight root canal systems. The study was performed on 99 single-rooted extracted teeth using the ProTaper Gold endodontic rotary system up to the F2 file (Dentsply Maillefer, Baillagues, Switzerland), which were sealed with GuttaCore (Dentsply Maillefer, Ballaigues, Switzerland) and AH plus epoxy resin sealer (Dentsply DeTrey, Konstanz, Germany) and randomly assigned to the following non-surgical retreatment techniques: ProTaper Retreatment endodontic rotary instruments (D1–D3 files, Dentsply Maillefer, Ballaigues, Switzerland; n = 33, PTR), Reciproc Blue endodontic reciprocating instrument (R50, VDW, Munich, Germany; n = 33, RCB50), and a combined root canal retreatment technique between Gates-Glidden drills (sizes #3 and #2, Dentsply Maillefer, Ballaigues, Switzerland) and Hedstrom files (file size 35, 30, and 25, Dentsply Maillefer, Ballaigues, Switzerland; n = 33; H-GG). All of the teeth were submitted twice to a micro-computed tomography (micro-CT) scan, before and after non-surgical endodontic retreatment procedures. The volume of root canal filling material (mm3), volume of remaining root canal filling material (mm3), non-surgical endodontic retreatment working time (min), proportion of remaining root canal filling material (%), and e cacy of root canal filling material removal between the non-surgical endodontic retreatment techniques were analyzed using ANOVA one-way statistical analysis. Statistically significant di erences were observed between the proportions of remaining root canal filling material of PTR and H-GG (p = 0.018), between the non-surgical endodontic retreatment working times (min; p < 0.001), and between the e cacies of root canal filling material removal by the non-surgical endodontic retreatment techniques (p = 0.009). However, the non-surgical endodontic retreatment systems allow for similar carrier-based root canal filling material removal.

The aim of this study was to compare the physicochemical properties, filling ability, and antibacterial activity of a premixed calcium silicate-based sealer to those of a powder–liquid bioceramic sealer. Ceraseal (CS) and BioRoot (BR) materials were analyzed using scanning electron microscopy and energy-dispersive X-ray spectroscopy at 7 and 14 d of immersion in distilled water. The filling ability of the two sealers as well as the water contact angle, solubility, flow, roughness, crystalline microstructure, pH, and compressive strength were also evaluated. The antibacterial activity was assessed through an agar di usion as well as through direct tests. All the results were statistically analyzed using one-way or two-way analysis of variance tests. Statistically significant lower void percentages were observed for CS at 2 and 8 mm from the working length (WL) compared to those for the BR group, whilst no significant di erence was observed at 5mmfrom the WL. BR sealer showed higher alkaline pH, rougher surface, lower water contact angle values, lower flowability, and higher solubility compared to CS. BR showed globular and needle-like crystalline microstructure, whilst CS had globular and flower-like crystalline microstructure up to 72 h. No statistical di erence was found for the compressive strength between the two sealers. BR and CS showed no antibacterial e ect against Enterococcus faecalis after 3 h, whilst both sealers showed antibacterial capacity after 24 and 72 h. BR demonstrated higher antibacterial activity after 24 h. In conclusion, the use of bioceramic sealers may play an important role in controlling bacterial growth. Moreover, CS may have superior filling ability and lower solubility than the BioRoot sealer due to its specific chemical composition and mixing method.

Quaternary ammonium compounds and calcium phosphates have been incorporated into dental materials to enhance their biointeractivity and preventive e ects. This study aimed at evaluating the physical and chemical properties and e ects against Streptococcus mutans of a dental sealant containing 1,3,5-tri acryloyl hexahydro-1,3,5-triazine (TAT) and -tricalcium phosphate ( -TCP). A methacrylate-based dental sealant was initially formulated. -TCP and TAT (G -TCPTAT) were added to the experimental sealant at 2 wt.% each. One group was formulated without -TCP and TAT and used as control (GCTRL). All tested resins were analyzed for polymerization kinetics and degree of conversion (DC %), Knoop hardness (KHN), softening in solvent (DKHN%), ultimate tensile strength (UTS), the contact angle with water or with -bromonaphthalene, surface free energy (SFE) and antibacterial activity against Streptococcus mutans in biofilm and in planktonic cells. The polymerization kinetic was di erent between groups, but without statistical di erences in the DC % (p < 0.05). KHN and DKHN% did not change between groups (p > 0.05), but G -TCPTAT presented greater UTS compared to GCTRL (p < 0.05). No di erences were found for contact angle (p > 0.05) or SFE (p > 0.05). G -TCPTAT showed greater antibacterial activity in comparison to GCTRL (p < 0.05). The formulation of dental sealants containing TAT and -TCP can be characterized by improved mechanical and antibacterial properties.

The aim of this study was to determine whether the residual presence of eugenol in coronal dentin may compromise the bond strength of resin-based restorative materials. A search was performed on MEDLINE/Pubmed, Scopus, and by hand search for relevant papers. No restriction was applied for language and publication date. The studies selected for analysis tested specimens with reduced size (micro-shear bond strength ( SBS) and micro-tensile bond strength ( TBS)) of adhesive systems and resin-based restorative materials applied to coronary dentin “contaminated” with eugenol-based materials. The search provided 335 articles, but only 10 studies met the inclusion criteria. The pooled global analysis showed a significant influence of eugenol, as it negatively influenced the bond strength of resin-based restorations (5.79 (3.31–8.28) MPa, p < 0.00001). The subgroup analyses for conventional etch-and-rinse (p = 0.003) and self-etch (p < 0.0004) adhesive systems, as well as for SBS (p = 0.01) and TBS (p < 0.0001), showed a negative influence of eugenol on the bond strength. Data were statistically heterogeneous. However, it was possible to observe that eugenol could negatively a ect the bonding of resin-based restorative materials to dentin. Further evidence is necessary in order to acquire more accurate information about this issue and confirm that the residual presence of eugenol in dentin compromises the bond strength of resin-based materials.