Nicola M Grande | Università Cattolica del Sacro Cuore (Catholic University of the Sacred Heart) (original) (raw)

Papers by Nicola M Grande

Journal of Biomedical Graphics and Computing, 2013

The 3D images of dental specimens were obtained by means of micro-Computed Tomography (µCT) befor... more The 3D images of dental specimens were obtained by means of micro-Computed Tomography (µCT) before and after therapeutic intervention. A suite of software tools has been developed to assess the efficacy of dental treatment as revealed by µCT scans. Endodontic root canal and restorative therapy were selected as model procedures to test and optimize the developed tools. Non destructive µCT imaging allows repeated scans of the same tooth and might provide quantitative information about specimen modifications over time. Preliminary literature has suggested that anatomical characterization and detailed evaluation of dental therapies would considerably benefit from the coupling between detailed 3D imaging and custom software. However, the main drawbacks reside in time consuming pipeline for scanner-time of the specimens and absence of efficient software for accurate data analysis and direct comparison of a set of 3D dental structures.

Registro della Stampa -Tribunale di Roma n. 131/88 del 1° marzo 1988 Redazione: Paola De Castro, ... more Registro della Stampa -Tribunale di Roma n. 131/88 del 1° marzo 1988 Redazione: Paola De Castro, Sara Modigliani e Sandra Salinetti La responsabilità dei dati scientifici e tecnici è dei singoli autori. © Istituto Superiore di Sanità 2005 Istituto Superiore di Sanità Valutazione delle caratteristiche a flessione di diversi tipi di perni endocanalari. Rossella Bedini, Raffaella Pecci, Nicola Maria Grande, Gianluca Plotino 2005, 32 p. Rapporti ISTISAN 05/7

Journal of oral & maxillofacial research, 2014

To compare the influence of type and dimensions of the apical preparation on the cleanliness of t... more To compare the influence of type and dimensions of the apical preparation on the cleanliness of the apical area in molars. A total of 120 root canals (MB and DB root canals from 30 maxillary molars and mesial root canals from 30 mandibular molars) were instrumented with Mtwo NiTi rotary instruments to a size 25/0.06 taper and were equally divided into three different experimental groups depending on the subsequently apical root canal preparation: Group 1: no further apical preparation, Group 2: apical preparation with Mtwo files to a size 40/0.04 taper, Group 3: apical preparation with Mtwo Apical Files. All root canals were observed through scanning electron microscopy (SEM). Presence of superficial debris and smear layer was evaluated using a score system. Data were statistically analysed using the Kruskal-Wallis and Bonferroni tests with a level of significance set at P < 0.05. Kruskal-Wallis test revealed no differences among groups in the middle and coronal third (P > 0.0...

Journal of endodontics, 2007

During the past few decades endodontic treatment has benefited from the development of new techni... more During the past few decades endodontic treatment has benefited from the development of new techniques and equipment, which have improved outcome and predictability. Important attributes such as the operating microscope and ultrasonics (US) have found indispensable applications in a number of dental procedures in periodontology, to a much lesser extent in restorative dentistry, while being very prominently used in endodontics. US in endodontics has enhanced the quality of treatment and represents an important adjunct in the treatment of difficult cases. Since its introduction, US has become increasingly more useful in applications such as gaining access to canal openings, cleaning and shaping, obturation of root canals, removal of intracanal materials and obstructions, and endodontic surgery. This comprehensive review of the literature aims at presenting the numerous uses of US in clinical endodontics and emphasizes the broad applications in a modern-day endodontic practice.

Dental Materials, 2007

ObjectivesTo evaluate the flexural modulus and flexural strength of different types of endodontic... more ObjectivesTo evaluate the flexural modulus and flexural strength of different types of endodontic post in comparison with human root dentin.

The aim of the present study was to investigate whether cyclic fatigue resistance is increased fo... more The aim of the present study was to investigate whether cyclic fatigue resistance is increased for nickeltitanium instruments manufactured by using new processes. This was evaluated by comparing instruments produced by using the twisted method (TF; SybronEndo, Orange, CA) and those using the M-wire alloy (GTX; Dentsply Tulsa-Dental Specialties, Tulsa, OK) with instruments produced by a traditional NiTi grinding process (K3, SybronEndo). Tests were performed with a specific cyclic fatigue device that evaluated cycles to failure of rotary instruments inside curved artificial canals. Results indicated that size 06-25 TF instruments showed a significant increase (p Ͻ 0.05) in the mean number of cycles to failure when compared with size 06-25 K3 files. Size 06-20 K3 instruments showed no significant increase (p Ͼ 0.05) in the mean number of cycles to failure when compared with size 06-20 GT series X instruments. The new manufacturing process produced nickel-titanium rotary files (TF) significantly more resistant to fatigue than instruments produced with the traditional NiTi grinding process. Instruments produced with M-wire (GTX) were not found to be more resistant to fatigue than instruments produced with the traditional NiTi grinding process. (J Endod 2008;34: 1003-1005

Introduction: Fractured rotary nickel-titanium (NiTi) instruments have been classified into those... more Introduction: Fractured rotary nickel-titanium (NiTi) instruments have been classified into those that fail as a result of cyclic flexural fatigue or torsional failure or a combination of both. Clinically, NiTi rotary instruments are subjected to both torsional load and cyclic fatigue, and ongoing research aims to clarify the relative contributions of both factors to instrument separation. Methods: To date, there is no specification or international standard to test cyclic fatigue resistance of endodontic rotary instruments. As a consequence, several devices and methods have been used to investigate in vitro cyclic fatigue fracture resistance of NiTi rotary endodontic instruments. In nearly all studies reported in the endodontic literature, the rotating instrument was either confined in a glass or metal tube, in a grooved block-and-rod assembly, or in a sloped metal block. Results: There has been no mention of the ''fit'' of the instrument in the tube or groove. As the instrument is likely to be fitting loosely, the description of the radius of curvature in those studies is likely to be overstated (ie, the file was actually bent less severely than reported, adding a variability in the amount of flexural stress). Conclusions: This review analyzed several devices that have been used in endodontic literature for cyclic fatigue testing and found that differences in the methodology affected the fatigue behavior of rotary instruments and, consequently, the outcome of these studies. An international standard for cyclic fatigue testing of NiTi rotary instruments is required to ensure uniformity of methodology and comparable results. (

The aim of the present study was to evaluate the bending properties of Hyflex instruments, which ... more The aim of the present study was to evaluate the bending properties of Hyflex instruments, which exhibit a lower percent in weight of nickel (52 Ni %wt) and compare them with other commercially available nickel-titanium (NiTi) rotary instruments. Methods: Ten instruments with tip size 25, 0.06 taper of each of the following NiTi rotary instrumentation techniques were selected for the study: Hyflex, EndoSequence, ProFile, Hero, and Flexmasters. All instruments from each group were tested for stiffness by comparing their bending moment when they attained a 45-degree bend. Experimental procedures strictly followed testing methodology described in ISO 3630-1. All data were recorded and subjected to statistical evaluation by using analysis of variance test. Statistical significance was set at P < .05). Results: Statistical analysis of the data revealed that Hyflex files were found to be the most flexible instruments, with a significant difference (P < .05) in comparison with the other instruments. Among the other files, a significant difference has been reported for EndoSequence instruments compared with ProFile, Hero, and FlexMaster (P < .05), whereas no significant differences have been reported among those 3 files (P > .05). Conclusions: Results of the present study have illustrated an increased flexibility of the new NiTi alloy over conventional NiTi alloy, and they highlight the potential of the new manufacturing process. (J Endod 2011;-:1-3)

ABSTRACT Objectives Aim of this study was to evaluate the cyclic fatigue resistance of two types ... more ABSTRACT Objectives Aim of this study was to evaluate the cyclic fatigue resistance of two types of new nickel-titanium endodontic instruments Materials and methods 80 instruments divided into 4 groups (20 each group), GTX 30/.06, GTX 40/.04, Twisted Files 30/.06, Twisted Files 40/.04. All the instruments were tested in two different artificial canals, one with a single curvature and the other with a double curvature. All instruments were rotated until fracture and the number of cycles to fracture (NCF) was then calculated, Results Twisted Files instruments resisted longer in rotation in the different canals. The size of the instrument (30.06, 40.04) did not have a statistically significant influence. Conclusions The instruments Twisted Files were more resistant to cyclic fatigue compared to the GTX.

Journal of Endodontics, 2008

The aim of this study was to compare the effectiveness of the Mtwo R (Sweden & Martina, Padova, I... more The aim of this study was to compare the effectiveness of the Mtwo R (Sweden & Martina, Padova, Italy), ProTaper retreatment files (Dentsply-Maillefer, Ballaigues, Switzerland), and a Hedström manual technique in the removal of three different filling materials (gutta-percha, Resilon [Resilon Research LLC, Madison, CT], and EndoRez [Ultradent Products Inc, South Jordan, UT]) during retreatment. Ninety single-rooted straight premolars were instrumented and randomly divided into 9 groups of 10 teeth each (n ϭ 10) with regards to filling material and instrument used. For all roots, the following data were recorded: procedural errors, time of retreatment, apically extruded material, canal wall cleanliness through optical stereomicroscopy (OSM), and scanning electron microscopy (SEM). A linear regression analysis and three logistic regression analyses were performed to assess the level of significance set at p ϭ 0.05. The results indicated that the overall regression models were statistically significant. The Mtwo R, ProTaper retreatment files, and Resilon filling material had a positive impact in reducing the time for retreatment. Both ProTaper retreatment files and Mtwo R showed a greater extrusion of debris. For both OSM and SEM logistic regression models, the root canal apical third had the greatest impact on the score values. EndoRez filling material resulted in cleaner root canal walls using OSM analysis, whereas Resilon filling material and both enginedriven NiTi rotary techniques resulted in less clean root canal walls according to SEM analysis. In conclusion, all instruments left remnants of filling material and debris on the root canal walls irrespective of the root filling material used. Both the engine-driven NiTi rotary systems proved to be safe and fast devices for the removal of endodontic filling material. (J Endod 2008;34:466 -469)

Journal of Endodontics, 2008

Tooth discoloration varies in etiology, appearance, localization, severity, and adhesion to tooth... more Tooth discoloration varies in etiology, appearance, localization, severity, and adhesion to tooth structure. It can be defined as being extrinsic or intrinsic on the basis of localization and etiology. In this review of the literature, various causes of tooth discoloration, different bleaching materials, and their applications to endodontically treated teeth have been described. In the walking bleach technique the root filling should be completed first, and a cervical seal must be established. The bleaching agent should be changed every 3-7 days. The thermocatalytic technique involves placement of a bleaching agent in the pulp chamber followed by heat application. At the end of each visit the bleaching agent is left in the tooth so that it can function as a walking bleach until the next visit. External bleaching of endodontically treated teeth with an in-office technique requires a high concentration gel. It might be a supplement to the walking bleach technique, if the results are not satisfactory after 3-4 visits. These treatments require a bonded temporary filling or a bonded resin composite to seal the access cavity. There is a deficiency of evidence-based science in the literature that addresses the prognosis of bleached nonvital teeth. Therefore, it is important to always be aware of the possible complications and risks that are associated with the different bleaching techniques. (J Endod 2008; 34:394 -407)

Journal of Endodontics, 2012

Introduction: The purpose of this study was to evaluate the effect of autoclave sterilization on ... more Introduction: The purpose of this study was to evaluate the effect of autoclave sterilization on cyclic fatigue resistance of rotary endodontic instruments made of traditional and new nickel-titanium (NiTi) alloys. Methods: Four NiTi rotary endodontic instruments of the same size (tip diameter 0.40 mm and constant .04 taper) were selected: K3, Mtwo, Vortex, and K3 XF prototypes. Each group was then divided into 2 subgroups, unsterilized instruments and sterilized instruments. The sterilized instruments were subjected to 10 cycles of autoclave sterilization. Twelve files from each different subgroup were tested for cyclic fatigue resistance. Means and standard deviations of number of cycles to failure (NCF) and fragment length of the fractured tip were calculated for each group, and data were statistically analyzed (P < .05). Results: Comparing the results between unsterilized and sterilized instruments for each type of file, differences were statistically significant (P < .05) only between sterilized and unsterilized K3XF files (762 versus 651 NCF). The other instruments did not show significant differences (P > .05) in the mean NCF as a result of sterilization cycles (K3, 424 versus 439 NCF; Mtwo, 409 versus 419 NCF; Vortex, 454 versus 480 NCF). Comparing the results among the different groups, K3 XF (either sterilized or not) showed a mean NCF significantly higher than all other files (P < .05). Conclusions: Repeated cycles of autoclave sterilization do not seem to influence the mechanical properties of NiTi endodontic instruments except for the K3 XF prototypes of rotary instruments that demonstrated a significant increase of cyclic fatigue resistance. (J Endod 2012;38:222-225)

Journal of Endodontics, 2011

Introduction: The purpose of this study was to assess the resistance to cyclic fatigue of three n... more Introduction: The purpose of this study was to assess the resistance to cyclic fatigue of three nickel-titanium (NiTi) files after the immersion in sodium hypochlorite (NaOCl) solution in conditions similar to those used in clinical practice. Methods: A total of 150 new Twisted Files (SybronEndo, Orange, CA), Revo S SU files (Micro Mega, Besancon, France), and Mtwo files (Sweden and Martina, Padova, Italy), size 25.06, were tested. Fifty files of the same brand were randomly assigned to five groups (n = 10) and submitted to the following immersion protocol in 5% NaOCl at 37 C for 16 mm: no immersion (control), 5 minutes statically, 1 minute statically, 5 minutes dynamically (300 rpm/min), and 1 minute dynamically. Resistance to cyclic fatigue was determined by counting the numbers of cycles to failure in a 60 curve with a 5-mm radius. Data were analyzed by two-way analyses of variance. Results: Resistance to cyclic fatigue of the same NiTi file was not significantly affected by immersion in NaOCl (P > .05). The Twisted File showed a higher resistance in all groups than Revo S SU (P < .001). The comparison between the same groups of Twisted Files and Mtwo files or between Mtwo and Revo S files did not show significant differences (P > .05) except for two cases: group 2 of the Twisted Files and Mtwo files and group 5 of the Mtwo and Revo S SU files (P < .05). Conclusions: Static or dynamic immersion in NaOCl for 1 minute or 5 minutes did not reduce the cyclic fatigue resistance of NiTi significantly. However, the type of instrument influences cyclic fatigue resistance. In our study, Twisted Files were more resistant followed by Mtwo and Revo S SU files. (J Endod 2011;37:1139-1142

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2008

Objective. The aims of this in vitro study were to measure root and canal diameters, root and can... more Objective. The aims of this in vitro study were to measure root and canal diameters, root and canal diameter ratios, mean taper of the root canal and of each root canal section, and radicular wall thickness at different levels in premolars with long oval root canals. Study design. Thirty human premolars, with single long oval canals were selected for this study. The specimens were analyzed with micro-computerized tomography. The cross-sections corresponding to 1, 2, 3, 4, 5, 7, 9, 11, and 13 mm from the radiologic apex were analyzed to measure the mesiodistal (MD) and buccolingual (BL) diameters of the canals and the thickness of the root and the walls. The BL/MD ratios of the canal (⌬C) and the root (⌬R) diameters were calculated, as was as the mean taper in both a BL and an MD dimension. Multiple logistic regression analyses were performed with a level of significance of P ϭ .05. Results. At all levels of analysis, the BL diameter was greater than the MD diameter for both the canal and the root. Generally, ⌬C and ⌬R increased coronally. Buccal and lingual wall thicknesses were greater than mesial and distal at all levels. Canal diameters at 1 mm from the apex were Ͼ0.30 mm in the shorter-oval diameter and Ͼ0.40 mm in the longer-oval diameter. In all root segments the BL taper was greater than the MD taper.

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2009

Objective. The objective of this study was to investigate the trajectory of NiTi rotary instrumen... more Objective. The objective of this study was to investigate the trajectory of NiTi rotary instruments of the same size but different design in an artificial root canal manufactured for cyclic fatigue test. Study design. Eight groups of instruments with tip size 25, 0.06 taper with different design were tested in a simulated root canal with an angle of curvature of 60 degrees and radius of curvature of 5 mm milled in a stainless steel block with a tapered shape corresponding to the dimensions of the instruments tested. Geometric analysis of the trajectory that each instrument followed inside the artificial canal was performed on digital images, determining 3 parameters: angle and radius of the curvature and the position of the center of the curvature. Mean values were then calculated for each group. Data were analyzed using 1-way ANOVA and Holm t test to determine any statistical difference (P Ͻ .05).

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2007

Objective. The objective of this study was to evaluate the influence of the moment when reduced p... more Objective. The objective of this study was to evaluate the influence of the moment when reduced pressure is applied on dye penetration patterns. Study design. Nine hundred and sixty glass capillary tubes of different inner diameter (0.3 mm and 0.8 mm), divided into 48 groups, were submerged into dye in 3 different positions (horizontally, opening upwards, and opening downwards) under different vacuum conditions (passive, 5 kPa, 35 kPa, 70 kPa reduced pressure). When reduced pressure was applied half of the groups were submerged into dye before and half of the groups after the application of reduced pressure. Linear dye penetration was measured. Univariate analysis was performed with Mann-Whitney U test and Kruskal-Wallis test to select variables to be included in the regression model. A multiple logistic regression analysis with backward elimination was performed to assess the influence of different covariates on linear dye penetration. Results. The multivariate linear regression showed that the moment of vacuuming had the greatest positive effect on linear dye penetration value (␤ ϭ 10.6, P Ͻ .0001). Also the level of pressure reduction had a positive effect on the outcome variable (␤ ϭ 0.2, P Ͻ .0001) while the vertical positioning of the tubes has negatively affected the outcome variable both for the open end upside (␤ ϭ Ϫ1.01, P ϭ .024) and the open end downside (␤ ϭ Ϫ1.05, P ϭ .019). Diameter of the tubes (P ϭ .442) and immersion time (P ϭ .727) had no effect on the outcome of linear dye penetration. Conclusions. Even minimum air pressure reduction applied before immersion of the specimens allowed the dye to extensively penetrate the voids. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103:289-94) a Professor,

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2007

To determine whether the shaping of oval-shaped root canals using 2 different preparation techniq... more To determine whether the shaping of oval-shaped root canals using 2 different preparation techniques resulted in significant morphologic differences. Study design. Forty lower premolars with oval-shaped root canals were divided into group A, instrumented with the Anatomic Endodontic Technology (AET) system, and group B, treated with ProTaper instruments. A modified Bramante technique was used to analyze changes in root canal diameters (⌬D), changes in surface area (⌬A), and the change in buccolingual and mesiodistal ratio (⌬R). The data were subjected to a Student t test at a significance level of P Ͻ 0.05. Results. Statistically significant differences were found between the 2 groups at coronal and middle levels. There was no statistically significant difference at the apical level. Conclusions. The 2 techniques produced a significant difference in the ultimate shape of the coronal and middle portions of oval-shaped root canals, with the AET system removing more tooth structure at these levels. However, no differences were observed at the apical third.

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2010

Objective. The aim of this study was to investigate the influence of the shape of 3 different art... more Objective. The aim of this study was to investigate the influence of the shape of 3 different artificial canals on the trajectory followed by different nickel-titanium rotary instruments. Study design. Ten ProFile and Mtwo instruments, tip sizes 20 and 25, taper .06, were tested in 3 simulated root canals with an angle of curvature of 60°and radius of curvature of 5 mm but with different shapes. Geometric analysis of the trajectory that each instrument followed inside the 3 different artificial canals was performed on digital images, determining 3 parameters: angle and radius of the curvature and the position of the center of the curvature. Mean values were then calculated for each instrument size in all of the artificial canals. Data were analysed using 1-way analysis of variance, Holm t test, and Student t test to determine any statistical difference (P Ͻ .05). Results. In all instrument sizes, a statistically significant difference was noted among the artificial canals for the radius and angle of curvature. No statistically significant difference was noted between instruments of the same size for the radius and angle of curvature and the position of the center of the curve when measured in the canal constructed on the dimension of the instruments. Conclusions. Different instruments follow different trajectories in artificial canals constructed with the same parameters of curvature but different shapes, depending on their different bending properties. All of the instruments respected the established parameters of curvature only when the artificial canal is designed on the dimension of the instruments.

Medical Science Monitor, 2014

The purpose of the present study was to introduce a new device specifically designed to evaluate ... more The purpose of the present study was to introduce a new device specifically designed to evaluate the cutting efficiency of mechanically driven endodontic instruments.

Journal of Endodontics, 2006

Recent studies detected erosion of the dentinal walls following the use of EDTA as a final flush.... more Recent studies detected erosion of the dentinal walls following the use of EDTA as a final flush. Several authors have studied degradation of EDTA and it appears to be caused by an oxidation reaction. The objective of this paper was to verify through nuclear magnetic resonance (NMR) analysis if the oxidizing property of sodium hypochlorite inactivates EDTA. Solutions of sodium hypochlorite and EDTA were analyzed. EDTA tracing and the appearance of new signals indicative of by-products of the reaction, were studied at different time intervals with a NMR analysis. The tracings of NMR analysis confirmed that the reaction between sodium hypochlorite and EDTA lead to a very slow but progressive degradation of this compound. Mindful of the limitations of an in vitro study, the results of this study nevertheless demonstrated that a final flush with sodium hypochlorite cannot limit the chelating effects of EDTA in a clinically realistic time period. (J Endod 2006;32:460 -464)

Journal of Biomedical Graphics and Computing, 2013

The 3D images of dental specimens were obtained by means of micro-Computed Tomography (µCT) befor... more The 3D images of dental specimens were obtained by means of micro-Computed Tomography (µCT) before and after therapeutic intervention. A suite of software tools has been developed to assess the efficacy of dental treatment as revealed by µCT scans. Endodontic root canal and restorative therapy were selected as model procedures to test and optimize the developed tools. Non destructive µCT imaging allows repeated scans of the same tooth and might provide quantitative information about specimen modifications over time. Preliminary literature has suggested that anatomical characterization and detailed evaluation of dental therapies would considerably benefit from the coupling between detailed 3D imaging and custom software. However, the main drawbacks reside in time consuming pipeline for scanner-time of the specimens and absence of efficient software for accurate data analysis and direct comparison of a set of 3D dental structures.

Registro della Stampa -Tribunale di Roma n. 131/88 del 1° marzo 1988 Redazione: Paola De Castro, ... more Registro della Stampa -Tribunale di Roma n. 131/88 del 1° marzo 1988 Redazione: Paola De Castro, Sara Modigliani e Sandra Salinetti La responsabilità dei dati scientifici e tecnici è dei singoli autori. © Istituto Superiore di Sanità 2005 Istituto Superiore di Sanità Valutazione delle caratteristiche a flessione di diversi tipi di perni endocanalari. Rossella Bedini, Raffaella Pecci, Nicola Maria Grande, Gianluca Plotino 2005, 32 p. Rapporti ISTISAN 05/7

Journal of oral & maxillofacial research, 2014

To compare the influence of type and dimensions of the apical preparation on the cleanliness of t... more To compare the influence of type and dimensions of the apical preparation on the cleanliness of the apical area in molars. A total of 120 root canals (MB and DB root canals from 30 maxillary molars and mesial root canals from 30 mandibular molars) were instrumented with Mtwo NiTi rotary instruments to a size 25/0.06 taper and were equally divided into three different experimental groups depending on the subsequently apical root canal preparation: Group 1: no further apical preparation, Group 2: apical preparation with Mtwo files to a size 40/0.04 taper, Group 3: apical preparation with Mtwo Apical Files. All root canals were observed through scanning electron microscopy (SEM). Presence of superficial debris and smear layer was evaluated using a score system. Data were statistically analysed using the Kruskal-Wallis and Bonferroni tests with a level of significance set at P < 0.05. Kruskal-Wallis test revealed no differences among groups in the middle and coronal third (P > 0.0...

Journal of endodontics, 2007

During the past few decades endodontic treatment has benefited from the development of new techni... more During the past few decades endodontic treatment has benefited from the development of new techniques and equipment, which have improved outcome and predictability. Important attributes such as the operating microscope and ultrasonics (US) have found indispensable applications in a number of dental procedures in periodontology, to a much lesser extent in restorative dentistry, while being very prominently used in endodontics. US in endodontics has enhanced the quality of treatment and represents an important adjunct in the treatment of difficult cases. Since its introduction, US has become increasingly more useful in applications such as gaining access to canal openings, cleaning and shaping, obturation of root canals, removal of intracanal materials and obstructions, and endodontic surgery. This comprehensive review of the literature aims at presenting the numerous uses of US in clinical endodontics and emphasizes the broad applications in a modern-day endodontic practice.

Dental Materials, 2007

ObjectivesTo evaluate the flexural modulus and flexural strength of different types of endodontic... more ObjectivesTo evaluate the flexural modulus and flexural strength of different types of endodontic post in comparison with human root dentin.

The aim of the present study was to investigate whether cyclic fatigue resistance is increased fo... more The aim of the present study was to investigate whether cyclic fatigue resistance is increased for nickeltitanium instruments manufactured by using new processes. This was evaluated by comparing instruments produced by using the twisted method (TF; SybronEndo, Orange, CA) and those using the M-wire alloy (GTX; Dentsply Tulsa-Dental Specialties, Tulsa, OK) with instruments produced by a traditional NiTi grinding process (K3, SybronEndo). Tests were performed with a specific cyclic fatigue device that evaluated cycles to failure of rotary instruments inside curved artificial canals. Results indicated that size 06-25 TF instruments showed a significant increase (p Ͻ 0.05) in the mean number of cycles to failure when compared with size 06-25 K3 files. Size 06-20 K3 instruments showed no significant increase (p Ͼ 0.05) in the mean number of cycles to failure when compared with size 06-20 GT series X instruments. The new manufacturing process produced nickel-titanium rotary files (TF) significantly more resistant to fatigue than instruments produced with the traditional NiTi grinding process. Instruments produced with M-wire (GTX) were not found to be more resistant to fatigue than instruments produced with the traditional NiTi grinding process. (J Endod 2008;34: 1003-1005

Introduction: Fractured rotary nickel-titanium (NiTi) instruments have been classified into those... more Introduction: Fractured rotary nickel-titanium (NiTi) instruments have been classified into those that fail as a result of cyclic flexural fatigue or torsional failure or a combination of both. Clinically, NiTi rotary instruments are subjected to both torsional load and cyclic fatigue, and ongoing research aims to clarify the relative contributions of both factors to instrument separation. Methods: To date, there is no specification or international standard to test cyclic fatigue resistance of endodontic rotary instruments. As a consequence, several devices and methods have been used to investigate in vitro cyclic fatigue fracture resistance of NiTi rotary endodontic instruments. In nearly all studies reported in the endodontic literature, the rotating instrument was either confined in a glass or metal tube, in a grooved block-and-rod assembly, or in a sloped metal block. Results: There has been no mention of the ''fit'' of the instrument in the tube or groove. As the instrument is likely to be fitting loosely, the description of the radius of curvature in those studies is likely to be overstated (ie, the file was actually bent less severely than reported, adding a variability in the amount of flexural stress). Conclusions: This review analyzed several devices that have been used in endodontic literature for cyclic fatigue testing and found that differences in the methodology affected the fatigue behavior of rotary instruments and, consequently, the outcome of these studies. An international standard for cyclic fatigue testing of NiTi rotary instruments is required to ensure uniformity of methodology and comparable results. (

The aim of the present study was to evaluate the bending properties of Hyflex instruments, which ... more The aim of the present study was to evaluate the bending properties of Hyflex instruments, which exhibit a lower percent in weight of nickel (52 Ni %wt) and compare them with other commercially available nickel-titanium (NiTi) rotary instruments. Methods: Ten instruments with tip size 25, 0.06 taper of each of the following NiTi rotary instrumentation techniques were selected for the study: Hyflex, EndoSequence, ProFile, Hero, and Flexmasters. All instruments from each group were tested for stiffness by comparing their bending moment when they attained a 45-degree bend. Experimental procedures strictly followed testing methodology described in ISO 3630-1. All data were recorded and subjected to statistical evaluation by using analysis of variance test. Statistical significance was set at P < .05). Results: Statistical analysis of the data revealed that Hyflex files were found to be the most flexible instruments, with a significant difference (P < .05) in comparison with the other instruments. Among the other files, a significant difference has been reported for EndoSequence instruments compared with ProFile, Hero, and FlexMaster (P < .05), whereas no significant differences have been reported among those 3 files (P > .05). Conclusions: Results of the present study have illustrated an increased flexibility of the new NiTi alloy over conventional NiTi alloy, and they highlight the potential of the new manufacturing process. (J Endod 2011;-:1-3)

ABSTRACT Objectives Aim of this study was to evaluate the cyclic fatigue resistance of two types ... more ABSTRACT Objectives Aim of this study was to evaluate the cyclic fatigue resistance of two types of new nickel-titanium endodontic instruments Materials and methods 80 instruments divided into 4 groups (20 each group), GTX 30/.06, GTX 40/.04, Twisted Files 30/.06, Twisted Files 40/.04. All the instruments were tested in two different artificial canals, one with a single curvature and the other with a double curvature. All instruments were rotated until fracture and the number of cycles to fracture (NCF) was then calculated, Results Twisted Files instruments resisted longer in rotation in the different canals. The size of the instrument (30.06, 40.04) did not have a statistically significant influence. Conclusions The instruments Twisted Files were more resistant to cyclic fatigue compared to the GTX.

Journal of Endodontics, 2008

The aim of this study was to compare the effectiveness of the Mtwo R (Sweden & Martina, Padova, I... more The aim of this study was to compare the effectiveness of the Mtwo R (Sweden & Martina, Padova, Italy), ProTaper retreatment files (Dentsply-Maillefer, Ballaigues, Switzerland), and a Hedström manual technique in the removal of three different filling materials (gutta-percha, Resilon [Resilon Research LLC, Madison, CT], and EndoRez [Ultradent Products Inc, South Jordan, UT]) during retreatment. Ninety single-rooted straight premolars were instrumented and randomly divided into 9 groups of 10 teeth each (n ϭ 10) with regards to filling material and instrument used. For all roots, the following data were recorded: procedural errors, time of retreatment, apically extruded material, canal wall cleanliness through optical stereomicroscopy (OSM), and scanning electron microscopy (SEM). A linear regression analysis and three logistic regression analyses were performed to assess the level of significance set at p ϭ 0.05. The results indicated that the overall regression models were statistically significant. The Mtwo R, ProTaper retreatment files, and Resilon filling material had a positive impact in reducing the time for retreatment. Both ProTaper retreatment files and Mtwo R showed a greater extrusion of debris. For both OSM and SEM logistic regression models, the root canal apical third had the greatest impact on the score values. EndoRez filling material resulted in cleaner root canal walls using OSM analysis, whereas Resilon filling material and both enginedriven NiTi rotary techniques resulted in less clean root canal walls according to SEM analysis. In conclusion, all instruments left remnants of filling material and debris on the root canal walls irrespective of the root filling material used. Both the engine-driven NiTi rotary systems proved to be safe and fast devices for the removal of endodontic filling material. (J Endod 2008;34:466 -469)

Journal of Endodontics, 2008

Tooth discoloration varies in etiology, appearance, localization, severity, and adhesion to tooth... more Tooth discoloration varies in etiology, appearance, localization, severity, and adhesion to tooth structure. It can be defined as being extrinsic or intrinsic on the basis of localization and etiology. In this review of the literature, various causes of tooth discoloration, different bleaching materials, and their applications to endodontically treated teeth have been described. In the walking bleach technique the root filling should be completed first, and a cervical seal must be established. The bleaching agent should be changed every 3-7 days. The thermocatalytic technique involves placement of a bleaching agent in the pulp chamber followed by heat application. At the end of each visit the bleaching agent is left in the tooth so that it can function as a walking bleach until the next visit. External bleaching of endodontically treated teeth with an in-office technique requires a high concentration gel. It might be a supplement to the walking bleach technique, if the results are not satisfactory after 3-4 visits. These treatments require a bonded temporary filling or a bonded resin composite to seal the access cavity. There is a deficiency of evidence-based science in the literature that addresses the prognosis of bleached nonvital teeth. Therefore, it is important to always be aware of the possible complications and risks that are associated with the different bleaching techniques. (J Endod 2008; 34:394 -407)

Journal of Endodontics, 2012

Introduction: The purpose of this study was to evaluate the effect of autoclave sterilization on ... more Introduction: The purpose of this study was to evaluate the effect of autoclave sterilization on cyclic fatigue resistance of rotary endodontic instruments made of traditional and new nickel-titanium (NiTi) alloys. Methods: Four NiTi rotary endodontic instruments of the same size (tip diameter 0.40 mm and constant .04 taper) were selected: K3, Mtwo, Vortex, and K3 XF prototypes. Each group was then divided into 2 subgroups, unsterilized instruments and sterilized instruments. The sterilized instruments were subjected to 10 cycles of autoclave sterilization. Twelve files from each different subgroup were tested for cyclic fatigue resistance. Means and standard deviations of number of cycles to failure (NCF) and fragment length of the fractured tip were calculated for each group, and data were statistically analyzed (P < .05). Results: Comparing the results between unsterilized and sterilized instruments for each type of file, differences were statistically significant (P < .05) only between sterilized and unsterilized K3XF files (762 versus 651 NCF). The other instruments did not show significant differences (P > .05) in the mean NCF as a result of sterilization cycles (K3, 424 versus 439 NCF; Mtwo, 409 versus 419 NCF; Vortex, 454 versus 480 NCF). Comparing the results among the different groups, K3 XF (either sterilized or not) showed a mean NCF significantly higher than all other files (P < .05). Conclusions: Repeated cycles of autoclave sterilization do not seem to influence the mechanical properties of NiTi endodontic instruments except for the K3 XF prototypes of rotary instruments that demonstrated a significant increase of cyclic fatigue resistance. (J Endod 2012;38:222-225)

Journal of Endodontics, 2011

Introduction: The purpose of this study was to assess the resistance to cyclic fatigue of three n... more Introduction: The purpose of this study was to assess the resistance to cyclic fatigue of three nickel-titanium (NiTi) files after the immersion in sodium hypochlorite (NaOCl) solution in conditions similar to those used in clinical practice. Methods: A total of 150 new Twisted Files (SybronEndo, Orange, CA), Revo S SU files (Micro Mega, Besancon, France), and Mtwo files (Sweden and Martina, Padova, Italy), size 25.06, were tested. Fifty files of the same brand were randomly assigned to five groups (n = 10) and submitted to the following immersion protocol in 5% NaOCl at 37 C for 16 mm: no immersion (control), 5 minutes statically, 1 minute statically, 5 minutes dynamically (300 rpm/min), and 1 minute dynamically. Resistance to cyclic fatigue was determined by counting the numbers of cycles to failure in a 60 curve with a 5-mm radius. Data were analyzed by two-way analyses of variance. Results: Resistance to cyclic fatigue of the same NiTi file was not significantly affected by immersion in NaOCl (P > .05). The Twisted File showed a higher resistance in all groups than Revo S SU (P < .001). The comparison between the same groups of Twisted Files and Mtwo files or between Mtwo and Revo S files did not show significant differences (P > .05) except for two cases: group 2 of the Twisted Files and Mtwo files and group 5 of the Mtwo and Revo S SU files (P < .05). Conclusions: Static or dynamic immersion in NaOCl for 1 minute or 5 minutes did not reduce the cyclic fatigue resistance of NiTi significantly. However, the type of instrument influences cyclic fatigue resistance. In our study, Twisted Files were more resistant followed by Mtwo and Revo S SU files. (J Endod 2011;37:1139-1142

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2008

Objective. The aims of this in vitro study were to measure root and canal diameters, root and can... more Objective. The aims of this in vitro study were to measure root and canal diameters, root and canal diameter ratios, mean taper of the root canal and of each root canal section, and radicular wall thickness at different levels in premolars with long oval root canals. Study design. Thirty human premolars, with single long oval canals were selected for this study. The specimens were analyzed with micro-computerized tomography. The cross-sections corresponding to 1, 2, 3, 4, 5, 7, 9, 11, and 13 mm from the radiologic apex were analyzed to measure the mesiodistal (MD) and buccolingual (BL) diameters of the canals and the thickness of the root and the walls. The BL/MD ratios of the canal (⌬C) and the root (⌬R) diameters were calculated, as was as the mean taper in both a BL and an MD dimension. Multiple logistic regression analyses were performed with a level of significance of P ϭ .05. Results. At all levels of analysis, the BL diameter was greater than the MD diameter for both the canal and the root. Generally, ⌬C and ⌬R increased coronally. Buccal and lingual wall thicknesses were greater than mesial and distal at all levels. Canal diameters at 1 mm from the apex were Ͼ0.30 mm in the shorter-oval diameter and Ͼ0.40 mm in the longer-oval diameter. In all root segments the BL taper was greater than the MD taper.

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2009

Objective. The objective of this study was to investigate the trajectory of NiTi rotary instrumen... more Objective. The objective of this study was to investigate the trajectory of NiTi rotary instruments of the same size but different design in an artificial root canal manufactured for cyclic fatigue test. Study design. Eight groups of instruments with tip size 25, 0.06 taper with different design were tested in a simulated root canal with an angle of curvature of 60 degrees and radius of curvature of 5 mm milled in a stainless steel block with a tapered shape corresponding to the dimensions of the instruments tested. Geometric analysis of the trajectory that each instrument followed inside the artificial canal was performed on digital images, determining 3 parameters: angle and radius of the curvature and the position of the center of the curvature. Mean values were then calculated for each group. Data were analyzed using 1-way ANOVA and Holm t test to determine any statistical difference (P Ͻ .05).

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2007

Objective. The objective of this study was to evaluate the influence of the moment when reduced p... more Objective. The objective of this study was to evaluate the influence of the moment when reduced pressure is applied on dye penetration patterns. Study design. Nine hundred and sixty glass capillary tubes of different inner diameter (0.3 mm and 0.8 mm), divided into 48 groups, were submerged into dye in 3 different positions (horizontally, opening upwards, and opening downwards) under different vacuum conditions (passive, 5 kPa, 35 kPa, 70 kPa reduced pressure). When reduced pressure was applied half of the groups were submerged into dye before and half of the groups after the application of reduced pressure. Linear dye penetration was measured. Univariate analysis was performed with Mann-Whitney U test and Kruskal-Wallis test to select variables to be included in the regression model. A multiple logistic regression analysis with backward elimination was performed to assess the influence of different covariates on linear dye penetration. Results. The multivariate linear regression showed that the moment of vacuuming had the greatest positive effect on linear dye penetration value (␤ ϭ 10.6, P Ͻ .0001). Also the level of pressure reduction had a positive effect on the outcome variable (␤ ϭ 0.2, P Ͻ .0001) while the vertical positioning of the tubes has negatively affected the outcome variable both for the open end upside (␤ ϭ Ϫ1.01, P ϭ .024) and the open end downside (␤ ϭ Ϫ1.05, P ϭ .019). Diameter of the tubes (P ϭ .442) and immersion time (P ϭ .727) had no effect on the outcome of linear dye penetration. Conclusions. Even minimum air pressure reduction applied before immersion of the specimens allowed the dye to extensively penetrate the voids. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;103:289-94) a Professor,

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2007

To determine whether the shaping of oval-shaped root canals using 2 different preparation techniq... more To determine whether the shaping of oval-shaped root canals using 2 different preparation techniques resulted in significant morphologic differences. Study design. Forty lower premolars with oval-shaped root canals were divided into group A, instrumented with the Anatomic Endodontic Technology (AET) system, and group B, treated with ProTaper instruments. A modified Bramante technique was used to analyze changes in root canal diameters (⌬D), changes in surface area (⌬A), and the change in buccolingual and mesiodistal ratio (⌬R). The data were subjected to a Student t test at a significance level of P Ͻ 0.05. Results. Statistically significant differences were found between the 2 groups at coronal and middle levels. There was no statistically significant difference at the apical level. Conclusions. The 2 techniques produced a significant difference in the ultimate shape of the coronal and middle portions of oval-shaped root canals, with the AET system removing more tooth structure at these levels. However, no differences were observed at the apical third.

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2010

Objective. The aim of this study was to investigate the influence of the shape of 3 different art... more Objective. The aim of this study was to investigate the influence of the shape of 3 different artificial canals on the trajectory followed by different nickel-titanium rotary instruments. Study design. Ten ProFile and Mtwo instruments, tip sizes 20 and 25, taper .06, were tested in 3 simulated root canals with an angle of curvature of 60°and radius of curvature of 5 mm but with different shapes. Geometric analysis of the trajectory that each instrument followed inside the 3 different artificial canals was performed on digital images, determining 3 parameters: angle and radius of the curvature and the position of the center of the curvature. Mean values were then calculated for each instrument size in all of the artificial canals. Data were analysed using 1-way analysis of variance, Holm t test, and Student t test to determine any statistical difference (P Ͻ .05). Results. In all instrument sizes, a statistically significant difference was noted among the artificial canals for the radius and angle of curvature. No statistically significant difference was noted between instruments of the same size for the radius and angle of curvature and the position of the center of the curve when measured in the canal constructed on the dimension of the instruments. Conclusions. Different instruments follow different trajectories in artificial canals constructed with the same parameters of curvature but different shapes, depending on their different bending properties. All of the instruments respected the established parameters of curvature only when the artificial canal is designed on the dimension of the instruments.

Medical Science Monitor, 2014

The purpose of the present study was to introduce a new device specifically designed to evaluate ... more The purpose of the present study was to introduce a new device specifically designed to evaluate the cutting efficiency of mechanically driven endodontic instruments.

Journal of Endodontics, 2006

Recent studies detected erosion of the dentinal walls following the use of EDTA as a final flush.... more Recent studies detected erosion of the dentinal walls following the use of EDTA as a final flush. Several authors have studied degradation of EDTA and it appears to be caused by an oxidation reaction. The objective of this paper was to verify through nuclear magnetic resonance (NMR) analysis if the oxidizing property of sodium hypochlorite inactivates EDTA. Solutions of sodium hypochlorite and EDTA were analyzed. EDTA tracing and the appearance of new signals indicative of by-products of the reaction, were studied at different time intervals with a NMR analysis. The tracings of NMR analysis confirmed that the reaction between sodium hypochlorite and EDTA lead to a very slow but progressive degradation of this compound. Mindful of the limitations of an in vitro study, the results of this study nevertheless demonstrated that a final flush with sodium hypochlorite cannot limit the chelating effects of EDTA in a clinically realistic time period. (J Endod 2006;32:460 -464)