Shaping ability of three nickel-titanium rotary instruments in simulated L-shaped canals: OneShape, Hero Shaper, and Revo-S.

BACKGROUND: Shaping ability of a file plays an important role during instrumentation in an endodontic treatment. This study aimed to compare the shaping ability of OneShape (OS), Hero Shaper (HS), and Revo-S (RS) instruments in simulated L-shaped canals. METHODS: Forty-eight simulated L-shaped canals were prepared to an apical size of 25 using OS, HS, and RS (all from Micro-Mega SA, Besançon, France), (n = 16 canals/group) systems. The amount of resin removed after each canal's preparation was measured and compared after producing a composite image made from the superimposition of pre and post-instrumented canals. Canal aberrations and the preparation time were also recorded. The data were statistically analysed by using ANOVA, Tukey, and Chi-square tests. RESULTS: One file fractured during instrumentation in the RS group. A significant difference was found at the apical end of the prepared simulated canal between the groups, with RS showing the least amount of resin removal from the inner side of the canals and HS showing the highest amount of resin removal from the outer side (P < 0.05). Regarding the total width of the canals after preparation, a significant difference was found between the groups at the apical end and the straight portion of the canals, and RS removed the least amount of resin at the straight portion of the canals (P < 0.05). No statistically significant differences were found between the different instruments regarding canal aberrations' incidence (P > 0.05). CONCLUSIONS: All of the files showed a tendency to straighten the canals, whereas OS files maintained the original canal curvatures well.

Revascularization of a Permanent Tooth with Necrotic Pulp and Apical Periodontitis.

This case report details a pulp revascularization treatment administered to a mature permanent tooth exhibiting pulp necrosis. A 22-years old female patient complained of the recurrence of a sinus tract labial of the maxillary right central incisor; which was tender on biting. Diagnosis of pulp necrosis and symptomatic apical periodontitis. Preoperative periapical and CBCT radiographs showed root with wide apical foramen and large apical radiolucency. Pulp revascularization procedure was performed using 1.3% sodium hypochlorite irrigation, 17% Ethylenediaminetetraacetic acid irrigation, and calcium hydroxide intracanal dressing for 2 weeks. During the last visit, intentional bleeding was induced, collagen matrix was set over the blood clot, 2 mm of mineral trioxide aggregate and glass-ionomer filling was placed. A year of follow-up, the tooth showed no signs or symptoms and responded normally to the sensibility tests. Intra-oral periapical radiograph and the CBCT showed significant reduction in the periapical lesion's size, slight reduction in the apical foramen's size, and hard radiopaque material deposition at the root's middle third.

Impact of Access Cavity Design on Fracture Resistance of Endodontically Treated Maxillary First Premolar: In Vitro.

This study was designed to investigate the impact of access cavity designs on fracture resistance of endodontically treated maxillary first premolars. The study sample consisted of 72 intact maxillary first premolars, randomly divided into six groups (n = 12). A standardized proximal cavity preparation was prepared for all samples using standard bur. Groups I: control group with only standard proximal cavity and no endodontic access, group II: Truss access cavity, group III: Separated access to buccal and palatal canals without removal of dentine in between, group IV: Access to buccal and palatal canals with removal of dentine in between, group V: Traditional access cavity, group VI: Mesio-occlusal-distal cavity (MOD). For groups I and VI, only composite restoration was used to restore the proximal cavity, while for groups II- V, the access was prepared and endodontic treatment was performed on all teeth, then composite restoration was placed. The root canals were instrumented using nickel-titanium files, irrigated with sodium hypochlorite, and filled with AH plus sealer and gutta-percha using warm vertical condensation. All samples were then placed in an acrylic mold and underwent thermal aging for 10,000 cycles between 5 and 55°C. The samples were fixed in a universal testing machine with the long axis of the roots positioned at 20° to a load applied at a crosshead speed of 1 mm/min using a stainless steel semi-spherical indenter (Ø = 3 mm) until fracture occurred to determine the fracture resistance force in Newton. The normality test (Shapiro-Wilk) showed that data are normally distributed. Group II exhibited the highest mean fracture resistance, and group VI was the least likely to resist the fracture. No statistically significant differences between tested groups (p-value = 0.237). The MOD group showed a more unfavorable mode of fracture compared to other groups. No significant difference in fracture resistance between conservative and traditional access cavities. The missing marginal ridges, such as in MOD cavities played an important role in decreasing the fracture resistance of endodontically treated teeth.

Surface Properties and Wear Resistance of Injectable and Computer-Aided Design/Computer Aided Manufacturing-Milled Resin Composite Thin Occlusal Veneers.

OBJECTIVES: This study was conducted to investigate the microhardness, surface roughness (Ra), and wear behavior of thin occlusal veneers (TOV) fabricated from different injectable composite materials and compare them to a Computer-Aided Design (CAD)/Computer-Aided Manufacturing (CAM) resin-based material. MATERIALS AND METHODS: A 1-mm occusal veneer preparation was done in a mandibular right second molar typodont tooth. The prepared model was duplicated to fabricate 32 replicas and divided into four groups (n = 8). Standard TOV were fabricated either indirectly from Cerasmart blocks, Cerasmart, GC (CS), or directly from Beautifil Injectable X, Shofu (BF), G-ænial Universal injectable, GC (GU), or SonicFill 2, Kerr (SF) using the injection molding technique. All the specimens were subjected to both thermomechanical cyclic loading (TMC) in a chewing simulator. Wear measurement was conducted by three-dimensional (3D) scanning of the veneered models before and after TMC, and the difference in the volume of the sample was recorded as the volumetric material loss due to wear. Ra before and after TMC and Vickers microhardness (VHN) of the tested materials were measured using standardized samples (n = 8). Representative samples from each group were investigated under a stereomicroscope and a scanning electron microscope. STATISTICAL ANALYSIS: One-way analysis of variance (ANOVA) was applied to detect the effect of material on VHN and wear. Two-way ANOVA was utilized to examine the impact of material and TMC on Ra. Multiple comparisons between the groups were conducted using Tukey's post hoc test (α = 0.05). The Pearson's correlation coefficient was used to determine the relationship between hardness and wear and between roughness and wear (α = 0.05). RESULTS: CS exhibited the highest mean VHN (p ≤ 0.001), followed by GU and SF which were statistically similar (p = 0.883) but significantly higher than BF (p < 0.001). After TMC, GU revealed the lowest Ra and volumetric wear (VW), followed by CS, BF, and SF (p < 0.5). A highly significant correlation existed between Ra and VW (p = 0.001, R 2 = 0.9803). CONCLUSION: The effect of TMC on the surface properties and wear resistance of the investigated TOV is material-dependent. GU injectable TOV are less influenced by TMC than CS milled TOV. In contrast, BF and SF demonstrated significant VW and Ra which might limit their clinical use as TOV.

Fracture resistance and failure mode of layered translucent zirconia with different crown designs.

This study investigated the impact of different veneering design on the fracture resistance and failure mode of layered translucent zirconia crowns, compared to the full monolithic zirconia crowns. Ninety crowns with different designs were divided into six groups (n=15); one fully contoured monolithic crown (FMC), one fully veneered with porcelain (FVC), or four partially veneered designs. All crowns were thermo-cycled, and then loaded to failure in a universal testing machine. The fracture resistance (N) and fracture modes were assessed. One-way ANOVA was performed followed by Tukey's multiple comparison (α<0.05). Results demonstrated that all the tested partially veneered designs exhibited enhanced fracture resistances and were comparable to that of the full-contour monolithic translucent zirconia crowns.

An in-vitro comparison of fracture resistance of three CAD/CAM Ceramic materials for fabricating Veneer.

AIMS: This research aims to measure and compare the fracture resistance and modes of failure of the following three chemically varied computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic veneering materials: IPS e.max CAD, Vita Enamic, and Shofu HC. MATERIALS AND METHODS: Twenty-seven sound human upper premolars were collected and stored in saline at room temperature until the experiment started and were assigned to three groups at random (n = 9). Putty indices were prepared to ensure a standardized butt joint preparation. An InEos X5 scanner was used to scan all the samples, and the resulting data were transferred to a CAD/CAM milling machine for veneer fabrication based on the materials used. Twenty-seven machined ceramic veneers were milled from three different ceramic materials. The cementation process was conducted for each material according to the manufacturer's instructions. To quantify the fracture resistance, all the samples underwent 2000 water cycles in a thermocycler and were then mounted in a universal testing machine at a 90° angle at the occlusal part of the veneer. The modes of failure were determined under a stereomicroscope and grouped into type I, ceramic fracture; type II, combined ceramic and tooth fracture; and type III, root fracture. RESULTS: Shofu HC had the highest mean (±standard deviation) fracture resistance (480.8 ± 92.8 N), followed by IPS e.max CAD (415.9 ± 147.2 N) and Vita Enamic (372.3 ± 123.9 N). However, the results of a one-way analysis of variance did not reveal statistically significant differences among the experimental groups (p = 0.194). The different groups exhibited different modes of failure, with ceramic fracture being the most common type of failure. CONCLUSION: All the materials tested in this study exhibited strong fracture resistance values, thereby indicating their use as veneering materials for the upper premolars.

Debris and Smear Layer Removal from Oval Root Canals Comparing XP-Endo Finisher, EndoActivator, and Manual Irrigation: A SEM Evaluation.

OBJECTIVE: This study aimed to assess and compare XP-Endo Finisher (XP) cleaning efficiency with respect to the amount of remaining debris and smear layer versus Max-I-Probe needle (CI), EndoActivator device (EA), and combination of XP-Endo Finisher file with EndoActivator device (XP+EA) in oval root canals. MATERIALS AND METHODS: This in vitro study was performed on 36 extracted single root/canal mandibular premolars. Radiographic images were taken in buccolingual and mesiodistal projections to evaluate the shape of the root canal and determine whether it met exclusion criteria. All teeth were decoronated and prepared using Reciproc (R40). The samples were divided randomly into four groups: CI, EA, XP, and XP + EA. The root canals were irrigated with 5 mL of 17% EDTA and 2.5% NaOCl, respectively. Apart from the CI group, both solutions were activated by using the tested techniques for 1 minute.The teeth were split longitudinally, and the best visible identified sections of the roots were used as the representing samples for scanning electron microscope (SEM) evaluation. Each half was divided into the following three parts: 1 mm from the anatomic apex and a standardized photomicrograph with 500x and 1500x magnifications for debris and smear layer were obtained. A five-grade scoring system was utilized to quantify the results at the coronal, middle, and apical regions. Statistical analysis was performed by using the Kruskal-Wallis and Mann-Whitney U tests. RESULTS: Group differences in debris and smear layer scores were found statistically significant for all locations as well as for overall assessment, except for the coronal third. Intragroup comparison of debris and smear layer in CI, EA, and XP had the minimum score at the middle third, with no significant difference compared with the coronal and apical thirds. XP + EA had less debris and smear layer score at the coronal third, significantly different from apical third.CI and EA had less debris and smear layer compared with XP and XP + EA at all locations with a significant difference at the middle and apical third (p < 0.05). CONCLUSION: EA and CI showed less debris and smear layer than XP and XP + EA in the middle and apical third. The use of the XP in conjunction with the present irrigation protocol failed to have debris-free dentin surface in the apical portion of most of the root canals.

Evaluating Fracture Resistance And Failure Modes Of Root Filled Teeth Restored With CAD/CAM-Fabricated Post And Core.

OBJECTIVE: The aim of this study was to measure the fracture resistance and failure modes of root-filled teeth restored with three different computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated post and core assemblies. METHODS: Thirty extracted intact maxillary central incisors were used in the study, and the teeth were endodontically treated and sectioned to a root length of 16 mm. The samples were divided into three groups (n = 10) according to the mean of the dimensions at the cervical portion of the root. The posts and cores were fabricated with CAD/CAM technology using metal, zirconia, and polymer-infiltrated ceramic network (PICN) material. The posts were luted using resin cement, and then, metal crowns were fabricated, cemented, and then subjected to a compression to determine the fracture resistance force. Fracture of the post and core or fracture of the root above the level of the acrylic resin was considered as a favorable fracture, while nonfavorable fractures were those where the root fracture occurred below the level of the acrylic resin. Statistical analysis was carried out using SPSS software, and one-way analysis of variance was used to analyze root fracture resistance in Newton. The number of failure modes, post-core fractures and/or root fractures was calculated. The differences between study groups were revealed using the chi-square test. RESULTS: The results of ANOVA revealed a nonsignificant difference in the resistance to fracture among the study groups (P = 0.114). The failure modes were nonfavorable for all metal and zirconia samples and seven PICN samples. However, three PICN samples exhibited a favorable represented by core fracture without root fracture. CONCLUSION: There was no significant difference between metal and zirconia samples in terms of nonfavorable fracture, while few PICN samples exhibited a favorable fracture. PICN material can be used in the fabrication of post and core assemblies using CAD/CAM.

Impact of Access Cavity Design on Fracture Resistance of Endodontically Treated Maxillary First Premolar: In Vitro

Abstract This study was designed to investigate the impact of access cavity designs on fracture resistance of endodontically treated maxillary first premolars. The study sample consisted of 72 intact maxillary first premolars, randomly divided into six groups (n = 12). A standardized proximal cavity preparation was prepared for all samples using standard bur. Groups I: control group with only standard proximal cavity and no endodontic access, group II: Truss access cavity, group III: Separated access to buccal and palatal canals without removal of dentine in between, group IV: Access to buccal and palatal canals with removal of dentine in between, group V: Traditional access cavity, group VI: Mesio-occlusal-distal cavity (MOD). For groups I and VI, only composite restoration was used to restore the proximal cavity, while for groups II- V, the access was prepared and endodontic treatment was performed on all teeth, then composite restoration was placed. The root canals were instrumented using nickel-titanium files, irrigated with sodium hypochlorite, and filled with AH plus sealer and gutta-percha using warm vertical condensation. All samples were then placed in an acrylic mold and underwent thermal aging for 10,000 cycles between 5 and 55°C. The samples were fixed in a universal testing machine with the long axis of the roots positioned at 20° to a load applied at a crosshead speed of 1 mm/min using a stainless steel semi-spherical indenter (Ø = 3 mm) until fracture occurred to determine the fracture resistance force in Newton. The normality test (Shapiro-Wilk) showed that data are normally distributed. Group II exhibited the highest mean fracture resistance, and group VI was the least likely to resist the fracture. No statistically significant differences between tested groups (p-value = 0.237). The MOD group showed a more unfavorable mode of fracture compared to other groups. No significant difference in fracture resistance between conservative and traditional access cavities. The missing marginal ridges, such as in MOD cavities played an important role in decreasing the fracture resistance of endodontically treated teeth.

Resumo O objetivo deste estudo foi investigar o impacto do design da cavidade de acesso na resistência à fratura de primeiros pré-molares superiores tratados endodonticamente. MÉTODOS: A amostra do estudo consistiu em 72 primeiros pré-molares superiores intactos, divididos aleatoriamente em seis grupos (n = 12). Um preparo padronizado da cavidade proximal foi realizado para todas as amostras usando broca padrão. Grupos I: grupo de controle com apenas cavidade proximal padrão e sem acesso endodôntico, grupo II: cavidade de acesso Truss, grupo III: acesso separado aos canais vestibular e palatino sem remoção de dentina entre eles, grupo IV: acesso aos canais vestibular e palatino com remoção de dentina entre eles, grupo V: cavidade de acesso tradicional, grupo VI: cavidade mesio-oclusal-distal (MOD). Para os grupos I e VI, apenas a restauração de compósito foi usada para restaurar a cavidade proximal. Já nos grupos II e V, o acesso foi preparado e o tratamento endodôntico foi realizado em todos os dentes e, em seguida, foi colocada a restauração de resina composta. Os canais radiculares foram instrumentados com limas de níquel-titânio, irrigados com hipoclorito de sódio e preenchidos com AH plus sealer e guta-percha usando condensação vertical quente. Todas as amostras foram então colocadas em molde de acrílico e submetidas a envelhecimento térmico por 10.000 ciclos entre 5 e 55°C. As amostras foram fixadas em uma máquina de teste universal com o eixo longo das raízes posicionado a 20° para uma carga aplicada a uma velocidade de cruzeta de 1 mm/min usando indentador semiesférico de aço inoxidável (Ø = 3 mm) até que ocorresse a fratura para determinar a força de resistência à fratura em Newton. RESULTADOS: O teste de normalidade (Shapiro-Wilk) mostrou que os dados são normalmente distribuídos. O grupo II apresentou a maior resistência média à fratura, e o grupo VI foi o menos propenso a resistir à fratura. Não houve diferenças estatisticamente significativas entre os grupos testados (p-valor = 0,237). O grupo MOD apresentou um modo de fratura mais desfavorável em comparação com os outros grupos. CONCLUSÕES: Não houve diferença significativa na resistência à fratura entre as cavidades de acesso conservador e tradicional. A ausência de cristas marginais, como nas cavidades MOD, desempenhou um papel importante na diminuição da resistência à fratura dos dentes tratados endodonticamente.