Removal of Root Canal Fillings in Curved Canals Using Either Mani GPR or HyFlex NT Followed by Passive Ultrasonic Irrigation.

This study compared the efficacy of HyFlex NT (HF; Coltene, New York, NY) and Mani GPR (MN; Mani Inc, Tokyo, Japan) systems followed by a supplementary approach with passive ultrasonic irrigation (PUI) in removing the filling material from curved root canals during retreatment. The mesial canals from 20 extracted mandibular molars with Vertucci type IV configuration were instrumented and obturated (N = 40). Each mesial canal was retreated using either HF or MN instruments, alternating the system used per canal from root to root. The final preparation size was 40/0.04 for both systems. The volume of canal filling material was assessed by means of micro-computed tomographic (micro-CT) imaging before and after retreatment, and the working time was recorded. Canals still showing remnants of filling material were subjected to a supplementary approach with PUI, and another micro-CT scan was taken. The percentage of filling material removed with MN instruments and HF was similar (95.5% and 92.7%, respectively) (P > .05). MN required significantly less time to remove the filling material (P < .05). The supplementary approach with PUI significantly enhanced the removal of filling material (P < .05). Both systems were equally effective in removing the root canal filling during retreatment. MN was faster than HF. The supplementary approach with PUI significantly improved filling material removal.

Influence of Surface Roughness on the Fatigue Life of Nickel-Titanium Rotary Endodontic Instruments.

INTRODUCTION: The goal of the present study was to evaluate the influence of surface grooves (peaks and valleys) resulting from machining during the manufacturing process of polished and unpolished nickel-titanium BR4C endodontic files on the fatigue life of the instruments. METHODS: Ten electropolished and 10 unpolished endodontic files were provided by the manufacturer. Specimens were from the same batch, but the unpolished instruments were removed from the production line before surface treatment. The instruments were evaluated with a profilometer to quantify the surface roughness on the working part of the instruments. Then the files were subjected to rotating bending fatigue tests. RESULTS: Analysis with the profilometer showed that surface grooves were deeper on the unpolished instruments compared with their electropolished counterparts. In the rotating bending fatigue test, the mean and standard deviation for the number of cycles until fracture (NCF) were greater for instruments with less pronounced grooves. Student t test revealed significant differences in all tests (P < .05). CONCLUSIONS: The results from the present study showed that the depth of the surface grooves on the working part affected the NCF of the instruments tested; the smaller the groove depth, the greater the NCF.

Fatigue Life of Reciproc and Mtwo instruments subjected to static and dynamic tests.

INTRODUCTION: This study evaluated the influence of flexibility and reciprocating movement on the fatigue life of endodontic instruments subjected to static and dynamic tests. METHODS: The rotary nickel-titanium instruments used in this study were Reciproc and Mtwo. The instruments were initially subjected to a cantilever-bending test and then to static and dynamic fatigue tests. Reciproc instruments were operated in reciprocating movement, whereas Mtwo instruments were worked in continuous rotation. RESULTS: The means of bending resistance (maximum load in grams) of the instruments were 274.9 for Reciproc and 429 for Mtwo. The mean times (in seconds) to fracture of the instruments subjected to static and dynamic tests were 214.5 (static) and 286.3 (dynamic) for Reciproc and 38.9 (static) and 99 (dynamic) for Mtwo. The Student's t test revealed significant differences in all tests (P < .05). CONCLUSIONS: The results of the present study showed longer fatigue life for instruments with higher flexibility, driven by reciprocating movement, and in the dynamic testing model. These findings reinforce the assumption that use of reciprocating movement is a means to prolong the fatigue life of rotary nickel-titanium endodontic instruments during instrumentation of curved canals.

Influence of the geometry of curved artificial canals on the fracture of rotary nickel-titanium instruments subjected to cyclic fatigue tests.

INTRODUCTION: This study evaluated the influence of different features of canal curvature geometry on the number of cycles to fracture of a rotary nickel-titanium endodontic instrument subjected to a cyclic fatigue test. METHODS: BioRaCe BR4C instruments (FKG Dentaire, La Chaux-de Fonds, Switzerland) were tested in 4 grooves simulating curved metallic artificial canals, each one measuring 1.5 mm in width, 20 mm in total length, and 3.5 mm in depth with a U-shaped bottom. The parameters of curvature including the radius and arc lengths and the position of the arc differed in the 4 canal designs. Fractured surfaces and helical shafts of the separated instruments were analyzed by scanning electron microscopy. RESULTS: The Student's t test showed that a significantly lower number of cycles to fracture values were observed for instruments tested in canals with the smallest radius, the longest arc, and the arc located in the middle portion of the canal. Scanning electron microscopic analysis of the fracture surfaces revealed morphologic characteristics of ductile fracture. Plastic deformation was not observed in the helical shaft of the fractured instruments. CONCLUSIONS: Curvature geometry including the radius and arc lengths and the position of the arc along the root canal influence the number of cycles to fracture of rotary nickel-titanium instruments subjected to flexural load.

Comparison of the mechanical properties of rotary instruments made of conventional nickel-titanium wire, M-wire, or nickel-titanium alloy in R-phase.

INTRODUCTION: This study compared the mechanical properties of endodontic instruments made of conventional nickel-titanium (NiTi) wire (K(3) and Revo-S SU), M-Wire (ProFile Vortex), or NiTi alloy in R-phase (K(3)XF). METHODS: The test instruments were subjected to mechanical tests to evaluate resistance to bending (flexibility), cyclic fatigue, and torsional load in clockwise rotation. Data were statistically evaluated by the analysis of variance test and the Student-Newman-Keuls test for multiple comparisons. RESULTS: In the bending resistance test, flexibility decreased in the following order: K(3)XF > Revo-S SU > ProFile Vortex > K(3). The ranking in the fatigue resistance test was the following: K(3)XF > K(3) > ProFile Vortex > Revo-S SU. In the torsional assay, the angular deflection at failure decreased in the following order: K(3)XF > Revo-S SU > K(3) > ProFile Vortex. For the maximum torque values, the ranking was K(3) > K(3)XF > ProFile Vortex > Revo-S SU. CONCLUSIONS: The results showed that the K(3)XF instrument, which is made of NiTi alloy in R-phase, had the overall best performance in terms of flexibility, angular deflection at failure, and cyclic fatigue resistance. In addition to the alloy from which the instrument is manufactured, the design and dimensions are important determinants of the mechanical performance of endodontic instruments.

Mechanical behavior of pathfinding endodontic instruments.

INTRODUCTION: This study compared the mechanical properties of 3 pathfinding endodontic instruments. METHODS: The test instruments were subjected to mechanical tests to evaluate resistance to bending (flexibility), buckling, cyclic fatigue, and torsional load in clockwise rotation. Data were statistically evaluated by analysis of variance and the Student-Newman-Keuls test for multiple comparisons. RESULTS: In the buckling resistance test, the highest values were observed for C-Pilot files (VDW, Munich, Germany) and the lowest for Scout RaCe (FKG Dentaire, La Chaux-de-Fonds, Switzerland) instruments. In the bending resistance test, the lowest flexibility was observed for the C-Pilot instrument, and no significant difference was observed between Scout RaCe and PathFile (Maillefer/Dentsply, Ballaigues, Switzerland) instruments. The ranking in the fatigue resistance test was the following: PathFile > Scout RaCe > C-Pilot, with statistically significant differences observed in the number of cycles to fracture between all the instruments. In the torsional assay, the angular deflection to fracture decreased in the following order: Scout RaCe > PathFile > C-Pilot. As for the maximum torque values, the ranking was as follows: C-Pilot > PathFile > Scout RaCe. CONCLUSIONS: Findings revealed that the stainless-steel C-Pilot instrument showed increased resistance to buckling but decreased flexibility and cyclic fatigue resistance when compared with nickel-titanium pathfinding instruments. PathFile instruments showed the highest resistance to cyclic fatigue, and Scout RaCe files exhibited the highest angular deflection to fracture. The different mechanical behavior of the instruments indicates that the combined use of stainless steel hand instruments and rotary nickel-titanium instruments during the exploration of narrow curved canals may be necessary to exploit the best performance of each pathfinding instrument.

Buckling resistance of pathfinding endodontic instruments.

INTRODUCTION: This study compared the buckling resistance of the following endodontic pathfinding instruments: C-Pilot file (VDW, Munich, Germany), C+ file (Maillefer/Dentsply, Ballaigues, Switzerland), and PathFile (Maillefer/Dentsply). METHODS: The test instruments were subjected to a devised buckling resistance test, which consisted of the application of an increasing load in the axial direction of the instrument by using a universal testing machine. The maximum load required to generate a lateral elastic displacement of 1 mm was recorded for each instrument. RESULTS: The results indicated that the buckling resistance decreased in the following order: C+ file > C-Pilot file > PathFile. The difference was statistically significant (P < .05). CONCLUSIONS: The stainless steel instruments (C+ and C-Pilot) were more resistant to buckling than the nickel-titanium instrument (PathFile). Considering that buckling resistance may influence the performance of instruments during the negotiation of constricted canals, the C+ files showed significantly better results than the other instruments tested.

Princípios biológicos do tratamento endodôntico de dentes com polpa viva / Biological principles of endodontic treatment of teeth with vital pulp

Na clínica endodôntica diuturna, o profissional se depara basicamente com três condições que requerem tratamento: polpas vitais, polpas necrosadas e casos de retratamento. O sucesso do tratamento endodôntico depende do reconhecimento das idiossincrasias de cada uma destas três condições. Canais radiculares contendo polpa viva são isentos de infecção, a qual geralmente se restringe à porção exposta da polpa coronária. O sucesso do tratamento endodôntico nestes casos então vai depender principalmente da manutenção da cadeia asséptica durante os procedimentos intracanais. Este artigo revisa os princípios biológicos do tratamento de dentes com polpa viva, visando fornecer ao clínico condições para melhorar o resultado do tratamento endodôntico destes casos.

Influence of different manufacturing methods on the cyclic fatigue of rotary nickel-titanium endodontic instruments.

INTRODUCTION: The aim of this study was to evaluate, by static and dynamic cyclic fatigue tests, the number of cycles to fracture (NCF) 2 types of rotary NiTi instruments: Twisted File (SybronEndo, Orange, CA), which is manufactured by a proprietary twisting process, and RaCe files (FKG Dentaire, La Chaux-de-Fonds, Switzerland), which are manufactured by grinding. METHODS: Twenty Twisted Files (TFs) and 20 RaCe files #25/.006 taper instruments were allowed to rotate freely in an artificial curved canal at 310 rpm in a static or a dynamic model until fracture occurred. RESULTS: Measurements of the fractured fragments showed that fracture occurred at the point of maximum flexure in the midpoint of the curved segment. The NCF was significantly lower for RaCe instruments compared with TFs. The NCF was also lower for instruments subjected to the static test compared with the dynamic model in both groups. Scanning electron microscopic analysis revealed ductile morphologic characteristics on the fractured surfaces of all instruments and no plastic deformation in their helical shafts. CONCLUSIONS: Rotary NiTi endodontic instruments manufactured by twisting present greater resistance to cyclic fatigue compared with instruments manufactured by grinding. The fracture mode observed in all instruments was of the ductile type.

Torsional resistance of retreatment instruments.

INTRODUCTION: This study compared the torsional resistance of two brands of rotary nickel-titanium (NiTi) instruments indicated for endodontic retreatment. METHODS: Mtwo retreatment instruments #15 and #25 (VDW, Munich, Germany) and ProTaper Universal retreatment instruments D2 and D3 (Maillefer/Dentsply, Ballaigues, Switzerland) were subjected to a torsional assay in clockwise rotation. The two parameters evaluated were maximum torque and angular deflection at failure. Fractured instruments had their fractured surfaces and helical shafts examined by scanning electron microscopy. RESULTS: The results indicated that the angular deflection at fracture decreased in the following order: Mtwo retreatment file #15 > Mtwo retreatment file #25 > ProTaper Universal retreatment file D2 > ProTaper Universal retreatment file D3. As for the maximum torque values, the results revealed the following descending order: ProTaper Universal file D2 > Mtwo retreatment file #25 > ProTaper Universal file D3 > Mtwo retreatment file #15. Scanning electron microscopic analysis revealed that plastic deformation occurred along the helical shaft of the fractured instruments. Fractured surfaces were of the ductile type. CONCLUSIONS: The instruments tested showed different torsional behavior depending on the parameter evaluated. If one considers that high angular deflection values may serve as a safety factor, then the Mtwo retreatment instruments showed significantly better results.

Torsional properties of pathfinding instruments.

INTRODUCTION: This study compared the torsional properties of 2 stainless steel endodontic pathfinding instruments: C-Pilot (VDW, Munich, Germany) and C(+) files (Maillefer/Dentsply, Ballaigues, Switzerland). Stainless steel conventional K-type instruments (KCC(+), VDW) were used as controls. METHODS: File sizes 10 were subjected to a torsional assay in clockwise rotation. The 2 parameters evaluated were maximum torque and angular deflection at failure. The fractured surfaces and the helical shafts of the fractured instruments were then examined by scanning electron microscopy (SEM). RESULTS: The results indicated that the angular deflection to fracture decreased in the following order: KCC(+) > C-Pilot > C(+). As for the maximum torque values, the results revealed the following descending order: C(+) > KCC(+) > C-Pilot. SEM analysis revealed that plastic deformation occurred along the helical shaft of the fractured instruments and that the fractured surfaces were of the ductile type. CONCLUSIONS: The instruments tested showed different torsional behavior depending on the parameter evaluated. Considering that high angular deflection values may serve as a safety factor for instruments used as pathfinders, the conventional K file showed significantly better results than both C-Pilot and C(+) files.

Comparison of some physical properties of finger spreaders made of stainless steel or nickel-titanium alloys.

The purpose of this study was to evaluate the flexibility, shape, and surface finishing of stainless steel (SS) and nickel-titanium (NiTi) finger spreaders as well as to compare the load required to insert these spreaders along a gutta-percha point adapted to the apical segment of curved or straight artificial canals. Instrument flexibility was investigated by using a universal testing machine in the cantilever-flexibility test. Scanning electron microscopy (SEM) was used to examine the shape and surface finishing of different sizes of SS and NiTi finger spreaders. Penetration load was evaluated only for spreaders size C by using the universal testing machine in a compressive test. As for flexibility, the load needed to bend the SS finger spreader sizes A, B, C, and D was approximately 167%, 146%, 102%, and 64% greater than the respective sizes of NiTi finger spreaders. SEM analysis revealed that the instrument tips were always tapered, but with different vertices. NiTi spreaders showed tips with circumferential grooves; whereas, those from SS spreaders exhibited longitudinal grooves. NiTi finger spreaders required a significantly higher penetration load than SS spreaders. This difference was probably related to the different shapes and surface finishing of the instrument tips. Different characteristics of finger spreaders may result in different clinical performance during the lateral compaction technique.

Effects of electropolishing surface treatment on the cyclic fatigue resistance of BioRace nickel-titanium rotary instruments.

INTRODUCTION: This study evaluated the influence of electropolishing surface treatment on the number of cycles to fracture of BioRace rotary nickel-titanium endodontic instruments. METHODS: BioRace size BR5C instruments with or without electropolishing surface treatment were used in an artificial curved canal under rotational speed of 300 rpm until fracture. Fractured surfaces and the helical shafts of fractured instruments were analyzed by scanning electron microscopy (SEM). RESULTS: Polished instruments displayed a significantly higher number of cycles to fracture when compared with nonpolished instruments (P < .001). Actually, the number of cycles to fracture of a polished BR5C instrument was 124% higher than that of a nonpolished instrument. SEM analysis showed that the fractured surface of both polished and nonpolished BR5C instruments had ductile morphologic characteristics. Evaluation of the separated fragments after cyclic fatigue testing showed the presence of microcracks near the fracture surface. Polished instruments exhibited fine cracks that assumed an irregular path (zigzag crack pattern), whereas nonpolished instruments showed cracks running along the machining grooves. CONCLUSIONS: Electropolishing surface treatment of BioRace endodontic instruments significantly increased the cyclic fatigue resistance.

Cyclic fatigue resistance of ProTaper Universal instruments when subjected to static and dynamic tests.

OBJECTIVE: This study evaluated the number of cycles to fracture of ProTaper Universal S2 instruments when subjected to static and dynamic cyclic fatigue tests. STUDY DESIGN: ProTaper Universal S2 instruments were used until fracture in an artificial curved canal under rotational speed of 300 rpm in either a static or a dynamic test model. Afterward, the length of the fractured segments was measured and fractured surfaces and helical shafts analyzed by scanning electron microscopy (SEM). RESULTS: The number of cycles to fracture was significantly increased when instruments were tested in the dynamic model (P<.001). Instrument separation occurred at the point of maximum flexure within the artificial canals, i.e., the midpoint of the curved canal segment. SEM analysis revealed that fractured surfaces exhibited characteristics of the ductile mode. Plastic deformation was not observed in the helical shaft of fractured instruments. CONCLUSIONS: The number of cycles to fracture ProTaper Universal S2 instruments significantly increased with the use of instruments in a dynamic cyclic fatigue test compared with a static model. These findings reinforce the need for performing continuous pecking motions during rotary instrumentation of curved root canals.

Estudo comparativo da resistência em flexão de instrumentos endodônticos de NiTi mecanizados / Comparative study of the bending resistance of engine-driven NiTi instruments

No presente trabalho avaliou-se e comparou-se a carga necessária para induzir uma determinada deformação elástica de instrumentos endodônticos de NiTi mecanizados de mesmo número e de quatro marcas comerciais. Nos ensaios mecânicos de flexão em cantilever os instrumentos foram fixados em uma das extremidades e a carga aplicada na extremidade oposta. Os resultados obtidos demonstraram que em termos de flexibilidade: TF > BioRace > K3 > ProTaper.

In the present study evaluated and compared the load required to induce a certain elastic deformation of NiTi endodontic instruments mechanized same number and four trademarks. In the mechanical cantilever bending the instruments were set at one end and the load applied at the opposite end. The results showed that in terms of flexibility: TF> BioRace> K3> ProTaper.

Comparison of the effectiveness of three irrigation techniques in reducing intracanal Enterococcus faecalis populations: an in vitro study.

INTRODUCTION: Several irrigation techniques have been recently introduced with the main objective of improving root canal disinfection. This in vitro study aimed at comparing the intracanal bacterial reduction promoted by chemomechanical preparation with 3 different irrigation techniques. METHODS: Root canals from extracted teeth were contaminated with Enterococcus faecalis ATCC 29212 for 7 days and then randomly distributed into 3 experimental groups of 20 teeth each: group 1, conventional irrigation with NaviTip needles inserted up to 3 mm short of the working length; group 2, same as group 1, but supplemented with final irrigant activation by the EndoActivator system; and group 3, irrigation with the EndoVac system. NaOCl and ethylenediaminetetraacetic acid (EDTA) were the irrigants used in all experimental groups. The overall preparation time was kept constant for the groups, but the total volume ranged from 20 mL (groups 1 and 2) to 43 mL (group 3). The control group was irrigated with saline solution (total volume, 43 mL). Samples taken before and after chemomechanical procedures were cultured, and the colony-forming units (CFUs) were counted. RESULTS: Reduction in the bacterial populations was highly significant for all groups. The 3 experimental groups with NaOCl and EDTA as irrigants were significantly more effective than the control group with saline in reducing CFU counts. There were no significant differences between the 3 techniques tested. CONCLUSIONS: There was no evident antibacterial superiority of any of the irrigation techniques evaluated in the present in vitro model.

Influence of rotational speed on the cyclic fatigue of rotary nickel-titanium endodontic instruments.

INTRODUCTION: During the preparation of curved canals, rotary nickel-titanium (NiTi) instruments are subjected to cyclic fatigue, which can lead to instrument fracture. Although several factors may influence the cyclic fatigue resistance of instruments, the role of the rotational speed remains uncertain. This study was intended to evaluate the effects of rotational speed on the number of cycles to fracture of rotary NiTi instruments. METHODS: ProTaper Universal instruments F3 and F4 (Maillefer SA, Ballaigues, Switzerland) were used in an artificial curved canal under rotational speeds of 300 rpm or 600 rpm. The artificial canal was made of stainless steel, with an inner diameter of 1.5 mm, total length of 20 mm, and arc at the end with a curvature radius of 6 mm. The arc length was 9.4 mm and 10.6 mm on the straight part. The number of cycles required to fracture was recorded. Fractured surfaces and the helical shafts of the fractured instruments were analyzed by scanning electron microscopy. RESULTS: The results showed approximately a 30% reduction in the observed number of cycles to fracture as rotational speed was increased from 300 to 600 RPM (p < 0.05). The morphology of the fractured surface was always of ductile type, and no plastic deformation was observed on the helical shaft of fractured instruments. CONCLUSIONS: The present findings for both F3 and F4 ProTaper instruments revealed that the increase in rotational speed significantly reduced the number of cycles to fracture.

Periradicular repair after two-visit endodontic treatment using two different intracanal medications compared to single-visit endodontic treatment.

The number of appointments necessary to treat infected root canals is one of the most controversial issues in endodontics. This study evaluated, in dogs, the response of the periradicular tissues to the endodontic treatment of infected root canals performed in a single visit or in two visits, using different interappointment dressings. Periradicular lesions were induced by inoculating Enterococcus faecalis in the root canals. After confirming that a periradicular lesion developed, the root canals were treated within one or two visits, using either ozonized oil or calcium hydroxide in camphorated paramonochlorophenol (CMCP) as an intracanal medication. After 6 months, the animals were sacrificed and the specimens were processed for histological and histobacteriological analysis. The root canals treated in a single visit showed a success rate of 46%. When a calcium hydroxide/CMCP-based interappointment intracanal medication was used, 74% of the cases were categorized as success. In cases where ozonized oil was used as the intracanal medication, a success rate of 77% was observed. These results of the present study demonstrated that the two-visit treatment offered a higher success rate compared to one-visit therapy. In addition, ozonized oil may potentially be used as an intracanal medication.

Eficácia antimicrobiana de diferentes medicamentos intracanais sobre Enterococcus faecalis, Candida albicans e Actinomyces radicidentis / Antimicrobial efficacy of different intracanal medicaments on Enterococcus faecalis, Candida albicans e Actinomyces radicidentis

O objetivo deste estudo in vitro foi investigar a eficácia de diferentes medicamentos intracanais contra Enterococcus faecalis, Candida albicans e Actinomyces radicidentis, três espécies microbianas detectadas em casos de fracasso da terapia endodôntica e com reconhecidos níveis de resistência ao hidróxido de cálcio. Os seguintes medicamentos foram testados: pasta de solução aquosa de clorexidina a 0,2% óxido de zinco e pastas de hidróxido de cálcio em glicerina, clorexidina a 0,2%, panamonoclorofenol, canforado/glicerina, iodeto de potássio iodetado ou iodo povidine. Os resultados demonstraram que a clorexidina associada ao óxido de zinco ou ao hidróxido de cálcio apresentou maior atividade antimicrobiana quando comparada aos outros medicamentos. Isso sugere que pastas contendo clorexidina podem ser consideradas para uso como medicamentação intracanal.

Periradicular repair after two-visit endodontic treatment using two different intracanal medications compared to single-visit endodontic treatment

The number of appointments necessary to treat infected root canals is one of the most controversial issues in endodontics. This study evaluated, in dogs, the response of the periradicular tissues to the endodontic treatment of infected root canals performed in a single visit or in two visits, using different interappointment dressings. Periradicular lesions were induced by inoculating Enterococcus faecalis in the root canals. After confirming that a periradicular lesion developed, the root canals were treated within one or two visits, using either ozonized oil or calcium hydroxide in camphorated paramonochlorophenol (CMCP) as an intracanal medication. After 6 months, the animals were sacrificed and the specimens were processed for histological and histobacteriological analysis. The root canals treated in a single visit showed a success rate of 46 percent. When a calcium hydroxide/CMCP-based interappointment intracanal medication was used, 74 percent of the cases were categorized as success. In cases where ozonized oil was used as the intracanal medication, a success rate of 77 percent was observed. These results of the present study demonstrated that the two-visit treatment offered a higher success rate compared to one-visit therapy. In addition, ozonized oil may potentially be used as an intracanal medication.

O número de sessões necessárias para tratar um canal radicular infectado é um dos assuntos mais controversos da endodontia. O objetivo deste estudo foi analisar, em cães, a resposta dos tecidos perirradiculares ao tratamento endodôntico de canais infectados em uma ou duas consultas, usando diferentes medicamentos entre as sessões. Lesões perirradiculares foram induzidas pela inoculação de Enterococcus faecalis nos canais. Após a confirmação do desenvolvimento de uma lesão perirradicular, os canais foram tratados em uma ou duas sessões, usando óleo ozonizado ou hidróxido de cálcio associado ao paramonoclorofenol canforado (PMCC) como medicação intracanal. Após 6 meses, os animais foram sacrificados e os espécimes processados para análise histológica e histobacteriológica. Os canais tratados em sessão única apresentaram uma taxa de sucesso de 46 por cento dos casos. Quando a medicação usada entre as sessões foi o hidróxido de cálcio associado com o PMCC, 74 por cento dos casos resultaram em sucesso. Nos casos em que o óleo ozonizado foi usado, uma taxa de sucesso de 77 por cento foi observada. Esses achados demonstraram que o tratamento em duas sessões oferece uma taxa de sucesso mais alta quando comparado à terapia em uma sessão. Além disso, o óleo ozonizado mostrou potencial para ser usado como medicação intracanal.