The impact of clinical use on the torsional behavior of Reciproc and WaveOne instruments

Torsional overload is a fracture representative parameter for instruments in single-file techniques. Objective The aim of this study was to assess the influence of clinical use, in vivo, on the torsional behavior of Reciproc and WaveOne instruments considering the possibility that they degraded with use. Material and Methods Diameter at each millimeter, pitch length, and area at 3 mm from the tip were determined for both types of instruments. Twenty-four instruments, size 25, 0.08 taper, of each system were divided into two groups (n=12 each): Control Group (CG), in which new Reciproc (RC) and WaveOne Primary (WO) instruments were tested in torsion until rupture based on ISO 3630-1; and Experimental Group (EG), in which each new instrument was clinically used to clean and shape the root canals of one molar. After clinical use, the instruments were analyzed using optical and scanning electron microscopy and subsequently tested in torsion until fracture. Data were analyzed using one-way analysis of variance at a=.05. Results WO instruments showed significantly higher mean values of cross-sectional area A3 (P=0.000) and smaller pitch lengths than RC instruments with no statistically significant differences in the diameter at D3 (P=0.521). No significant differences in torsional resistance between the RC and WO new instruments (P=0.134) were found. The clinical use resulted in a tendency of reduction in the maximum torque of the analyzed instruments but no statistically significant difference was observed between them (P=0.327). During the preparation of the root canals, two fractured RC instruments and longitudinal and transversal cracks in RC and WO instruments were observed through SEM analysis. Conclusion After clinical use, no statistically significant reduction in the torsional resistance was observed

In vitro assessment of torque and force generated by novel ProTaper Next Instruments during simulated canal preparation.

INTRODUCTION: The purpose of this study was to assess torque and force for simulated canal preparation with a new root canal instrument, ProTaper Next. METHODS: Six sets of ProTaper Next Instruments (X1-X5) were used to prepare 36 artificial canals. Files were divided into 6 groups. Different settings of rotations per minute (250, 300, and 350 rpm) and numbers of in-and-out movements to reach working length (3 or 4 insertions [ins]) were applied in each group (250 rpm/3 ins, 250 rpm/4 ins, 300 rpm/3 ins, 300 rpm/4 ins, 350 rpm/3 ins, and 350 rpm/4 ins) by using an automated torque bench. Peak torques (Ncm) as well as positive and negative forces (N) were registered. Analysis of variance and Tukey post hoc tests were applied. Preliminary data for angle and stationary torque at failure were also obtained and compared with peak torque for each instrument. RESULTS: Significant differences in peak torque (P \u3c .0001), positive force (P \u3c .002), and negative force (P \u3c .0001) were found for ProTaper Next instruments overall. X2 showed the highest torque with all settings. X5 showed the highest positive force in all groups. X1 and X2 showed the highest negative forces for all groups except for 350 rpm/4 ins. Significantly lower torque (P \u3c .0001) and positive force (P \u3c .007) were measured in the group 350 rpm/4 ins for all instruments except for X4. In contrast, X1 showed a significantly lower negative force for 350 rpm/4 ins. Torque at failure according to American Dental Association no. 28/ISO 36030-1 was lower for X1, X2, and X3 than torque during simulated canal preparation (P \u3c .0001). CONCLUSIONS: Under the conditions of this study, using ProTaper Next at 350 rpm and with 4 in-and-out movements resulted in lowest levels of peak torque as well as positive and negative forces

AVALIAÇÃO DE TRATAMENTOS ENDODÔNTICOS REALIZADOS POR ALUNOS DE GRADUAÇÃO- um estudo de seguimento. EVALUATION OF ENDODONTIC TREATMENTS PERFORMED BY GRADUATION STUDENTS- a cohort study

Objetivo: Realizar análises clínica e radiográfica dos dentes tratadosendodonticamente por alunos de graduação da Faculdade de Odontologiada Universidade Federal da Bahia (FOUFBA). Material e Métodos:Realizou-se um estudo de coorte retrospectivo, com os prontuáriosdos pacientes atendidos na Disciplina de Endodontia Clínica daFOUFBA no período de Março de 2013 a Março de 2015 e novo exameem 2017. Foram avaliadas as condições socioeconômicas e característicasclínicas dos elementos dentais. Resultados: Na análise descritiva,os pacientes estavam entre as idades de 12 a 72 anos. Quanto aogênero, de um total de 70 pacientes, 68,57% (n = 48) eram do gênerofeminino e 31,43% (n = 22) do masculino. Cerca da metade dos pacientesestudou até o Ensino Médio (57,14%; n = 40) e a maioria apresentourenda de 1 a 2 salários mínimos (74,29%; n = 52). Houve associação estatisticamentesignificativa entre a variável de desfecho necrose pulpare regressão da lesão periapical (P = 0,050). A variável independenterenda foi mais preditora do que a escolaridade dos pacientes e mostrou-se associada à exodontia (P = 0,052). A maioria dos pacientes quetiveram atendimentos posteriores externos à Faculdade realizou exodontiado dente em questão (88,89%), sendo esta associação estatisticamentesignificativa (P = 0,052). Conclusão: Observou-se um bompercentual de sucesso do tratamento realizado em ambiente acadêmico,como regressão de lesões periapicais, reconhecimento das indicaçõesde tratamentos posteriores como restaurações ou exodontiasfornecendo subsídios para o desenvolvimento de novas práticas noserviço da Faculdade de Odontologia da UFBA.ABSTRACTObjective: To carry out clinical and radiographic analysis of teeth endodonticallytreated by undergraduate students of the Faculty of Dentistryof the Federal University of Bahia (FOUFBA). Material and Methods:A retrospective cohort study was conducted using the medicalrecords of the patients treated in the Endodontic Clinical Disciplineof FOUFBA from March 2013 to March 2015 and a new examination in2017. The socioeconomic conditions and clinical characteristics of thedental elements were evaluated. Results: In descriptive data, patientswere between the ages of 12 to 72 years. Regarding gender, out of a totalof 70 patients, 68.57% (n = 48) were of the female gender and 31.43%(n = 22) were male. About half of the patients studied until high school (57.14%, n = 40) and the majority presented income of 1 to 2 minimumwages (74.29%, n = 52). There was a statistically significant associationbetween the outcome variable pulp necrosis and periapical lesionregression (P = 0.050). The independent variable income was morepredictive than the schooling of the patients and was associated withthe exodontia (P = 0.052). The majority of the patients who had posteriorcare outside the Faculty performed tooth extraction (88.89%),being this association statistically significant (P = 0.052). Conclusion: Asignificant percentage of treatment success was observed in the academicsetting, such as regression of periapical lesions, recognition ofindications for subsequent treatments like restorations or exodontia,providing subsidies for the development of new practices in the UFBASchool of Dentistry

Behavior of nickel-titanium instruments manufactured with different thermal treatments.

INTRODUCTION: The purpose of this study was to investigate if nickel-titanium instruments with similar designs manufactured by different thermal treatments would exhibit significantly different in vitro behavior. METHODS: Thirty-six instruments each of ProTaper Universal (PTU F1; Dentsply Maillefer, Ballaigues, Switzerland), ProFile Vortex (PV; Dentsply Tulsa Dental Specialties, Tulsa, OK), Vortex Blue (VB, Dentsply Tulsa Dental Specialties), and TYPHOON Infinite Flex NiTi (TYP; Clinician\u27s Choice Dental Products, New Milford, CT) (all size 25/.06) were evaluated. Bending resistance, torsion at failure, and dynamic torsional tests were performed with the instruments (n = 12). Analysis of variance and Tukey post hoc tests were applied. RESULTS: Flexibility was significantly higher for TYP compared with the other 3 groups (P \u3c .0001). With respect to the maximum torque at failure, PV group showed the highest resistance to twisting (torsional strength) among the analyzed instruments followed by VB, TYP, and PTU. The TYP group exhibited greater angular deflection at failure compared with the other groups (P \u3c .0001). The mean dynamic torque scores during simulated canal preparation were highest for TYP (3.01 ± 0.71 Ncm) and lowest for PV (1.62 ± 0.79 Ncm). However, no significant differences were observed comparing groups PTU with TYP and VB and VB with PV (P \u3e .05). The highest mean forces were recorded with PTU (7.02 ± 2.36 N) and the lowest with TYP (1.22 ± 0.40 N). CONCLUSIONS: TYP instruments were significantly more flexible than the other instruments tested. The PV group had the highest torsional strength and TYP, despite being the most flexible, showed similar torsional moments to the other instruments, whereas its angular deflection was the highest among the groups

PERFIL EPIDEMIOLÓGICO DOS PACIENTES E TRATAMENTOS REALIZADOS NA DISCIPLINA DE ENDODONTIA / EPIDEMIOLOGICAL PROFILE OF PATIENTS AND TREATMENTS PERFORMED IN THE ENDODONTIC CLINIC

Objetivo: Este trabalho teve como objetivo verificar o perfil epidemiológicoda população atendida e dos tratamentos realizados na disciplinade Endodontia da Faculdade de Odontologia da Universidade Federal daBahia (FOUFBA). Materiais e Métodos: Foi realizado um estudo ObservacionalRetrospectivo com a análise de prontuários de pacientes atendidosna disciplina no período de 2014 a 2017, constituindo uma amostrade 373 prontuários. Foram coletados os seguintes dados: gênero, idade,etiologia da alteração pulpar, queixa principal, elemento dentário tratadoendodonticamente e diagnóstico. Resultados: Os resultados demonstrarammaior ocorrência do gênero feminino (62%), na faixa etária de 31 a40 anos (n=74), sem diferença estaticamente significante entre ambos ossexos. A etiologia da alteração pulpar, na maior parte dos casos, foi relacionadacom a doença cárie (n=327), seguido de traumatismos dentários(n=40) e em menor parte por outros motivos, incluindo finalidade protética(n=6), acometendo indistintamente indivíduos de ambos os gêneros(P<0,05). Os dentes mais acometidos foram os pré-molares (n=178), seguidospelos incisivos (n=117) (P<0,05). Quanto ao diagnóstico, as patologiaspulpares e periapicais encontradas foram em ordem decrescente: PulpiteIrreversível Sintomática (40%), Periodontite Apical Assintomática (29,5%),Necrose Pulpar sem lesão periapical (25,7%) e 4,8% Retratamentos devidoà reinfecção do canal radicular. A dor foi a queixa principal mais relatada(70,5%), seguida de encaminhamentos de outras disciplinas (26,2%), oucom finalidade protética sem sinal ou sintoma de alteração pulpar (2,9%).Conclusões: Observou-se a importância de traçar metas para prevençãodas doenças pulpares nos pacientes e melhoria dos tratamentos endodônticosrealizados na FOUFBA.Objective: This study aimed to verify the epidemiological profile of thepopulation served and the treatments performed in the Endodonticsdiscipline of the Faculty of Dentistry of the Federal University of Bahia(FOUFBA). Materials and Methods: A Retrospective Observational studywas carried out with the analysis of medical records of patients attendedin the discipline from 2014 to 2017, constituting a sample of 373 medicalrecords. The following data were collected: gender, age, etiology ofpulpal alteration, main complaint, endodontically treated dental elementand diagnosis. Results: The results showed a greater occurrence of thefemale gender (62%), in the age group of 31 to 40 years (n=74), withoutstatistically significant difference between both sexes. The etiology ofpulpal alteration was, in most cases, related to caries disease (n=327), followedby dental trauma (n=40), and to a lesser extent by other reasons, includingprosthetic purpose (n=6). indistinctly individuals of both genders(P<0.05). The most affected teeth were the premolars (n=178), followed bythe incisors (n=117) (P<0.05). As to the diagnosis, the pulp and periapicalpathologies found were in descending order: Symptomatic IrreversiblePulpitis (40%), Asymptomatic Apical Periodontitis (29.5%), Pulp Necrosiswithout periapical lesion (25.7%) and 4.8% Retreatment due to reinfectionof the root canal. Pain was the most reported major complaint (70.5%),followed by referrals from other disciplines (26.2%), or with prostheticpurpose with no sign or pulp alteration symptom (2.9%). Conclusions: Inconclusion, it was observed the importance of establishing goals for theprevention of pulp diseases in patients and improvement of endodontictreatments performed at FOUFBA

Validated finite element analyses of WaveOne Endodontic Instruments: a comparison between M-Wire and NiTi alloys.

AIM: To validate torsional analysis, based on finite elements, of WaveOne instruments against in vitro tests and to model the effects of different nickel-titanium (NiTi) materials. METHODOLOGY: WaveOne reciprocating instruments (Small, Primary and Large, n = 8 each, M-Wire) were tested under torsion according to standard ISO 3630-1. Torsional profiles including torque and angle at fracture were determined. Test conditions were reproduced through Finite Element Analysis (FEA) simulations based on micro-CT scans at 10-μm resolution; results were compared to experimental data using analysis of variance and two-sided one sample t-tests. The same simulation was performed on virtual instruments with identical geometry and load condition, based on M-Wire or conventional NiTi alloy. RESULTS: Torsional profiles from FEA simulations were in significant agreement with the in vitro results. Therefore, the models developed in this study were accurate and able to provide reliable simulation of the torsional performance. Stock NiTi files under torsional tests had up to 44.9%, 44.9% and 44.1% less flexibility than virtual M-Wire files at small deflections for Small, Primary and Large instruments, respectively. As deflection levels increased, the differences in flexibility between the two sets of simulated instruments decreased until fracture. Stock NiTi instruments had a torsional fracture resistance up to 10.3%, 8.0% and 7.4% lower than the M-Wire instruments, for the Small, Primary and Large file, respectively. CONCLUSION: M-Wire instruments benefitted primarily through higher material flexibility while still at low deflection levels, compared with conventional NiTi alloy. At fracture, the instruments did not take complete advantage of the enhanced fractural resistance of the M-Wire material, which determines only limited improvements of the torsional performance

Influence of clinical use on physical-structural surface properties and electrochemical potential of NiTi endodontic instruments.

AIM: To investigate the surface morphology and electrochemical potential of superelastic (SE), M-Wire (MW) and shape memory technology (SMT) NiTi instruments before and after single clinical use in vivo. METHODOLOGY: A total of 60 ProTaper Universal F2 (PTU-SE), ProTaper Next X2 (PTN-MW), Typhoon (TYP), Hyflex (HF) and Vortex Blue (VB), the last three SMT, and size 25, .06 taper (n = 6 of each type) files were examined. Scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS) and electrochemical potential analysis were employed before and after clinical use. Statistical analysis was performed with one-way analysis of variance and Bonferroni\u27s post hoc test. Significance was determined at the 95% confidence level for both tests. RESULTS: SEM observations of new instruments indicated the presence of marks left by the machining process during manufacturing and EDS revealed the existence of an oxide coating on shape memory instruments. After clinical use, the five types were associated with propagation of transverse cracks 3 mm from the tip. The surface oxide layer of TYP, HF and VB instruments had microcracks in multiple directions, whilst TYP and HF had fragmentation in chip form of the oxide layer. EDS analysis demonstrated a significant reduction of the oxide layer in shape memory instruments, except for VB. Electrochemical potentials were higher for shape memory instruments than for M-Wire and superelastic NiTi instruments, respectively (P \u3c 0.05). CONCLUSIONS: It appears that shape memory technology NiTi instruments have a dysfunctional oxide layer after clinical use. Additionally, they featured higher electrochemical potential relative to NiTi instruments manufactured from M-Wire, and conventional superelastic NiTi alloy

Mechanical behavior of M-Wire and conventional NiTi wire used to manufacture rotary endodontic instruments.

OBJECTIVE: Comparison of physical and mechanical properties of one conventional and a new NiTi wire, which had received an additional thermomechanical treatment. METHODS: Specimens of both conventional (NiTi) and the new type of wire, called M-Wire (MW), were subjected to tensile and three-point bending tests, Vickers microhardness measurements, and to rotating-bending fatigue tests at a strain-controlled level of 6%. Fracture surfaces were observed by scanning electron microscopy and the non-deformed microstructures by transmission electron microscopy. RESULTS: The thermomechanical treatment applied to produce the M-Wire apparently increased the tensile strength and Vickers microhardness of the material, but its apparent Young modulus was smaller than that of conventionally treated NiTi. The three-point bending tests showed a higher flexibility for MW which also exhibited a significantly higher number of cycles to failure. SIGNIFICANCE: M-Wire presented mechanical properties that can render endodontic instruments more flexible and fatigue resistant than those made with conventionally processed NiTi wires