FACULDADE IMED
MESTRADO EM ODONTOLOGIA
ALÂNIA AGASSIS DO NASCIMENTO DALLA VALLE
PAPEL DA TÉCNICA DE PREPARO ENDODÔNTICO NA
FORMAÇÃO E PROPAGAÇÃO DE DEFEITOS
DENTINÁRIOS: REVISÃO SISTEMÁTICA
PASSO FUNDO
2018
ALÂNIA AGASSIS DO NASCIMENTO DALLA VALLE
PAPEL DA TÉCNICA DE PREPARO ENDODÔNTICO NA FORMAÇÃO E PROPAGAÇÃO DE DEFEITOS DENTINÁRIOS: REVISÃO SISTEMÁTICA
Dissertação apresentada ao Programa de Pós-Graduação em Odontologia da Faculdade IMED, como requisito parcial à obtenção do título de Mestre em Odontologia.
Professor orientador: Prof. Dr. Gabriel Kalil Rocha Pereira Professor co-orientador: Dr. Rafael Sarkis-Onofre
PASSO FUNDO 2018
CIP – Catalogação na Publicação D136p DALLA VALLE, Alânia Agassis do Nascimento
Papel da técnica de preparo endodôntico na formação e propagação de defeitos dentinários: revisão sistemática / Alânia Agassis do Nascimento Dalla Valle. – 2018.
68 f.; 30 cm.
Dissertação (Mestrado em Odontologia) – Faculdade IMED, Passo Fundo, 2018.
Orientador: Prof. Dr. Gabriel Kalil Rocha Pereira.
1. Tratamento endodôntico. 2. Formação de Microtrincas. 3.
Odontologia – Tratamento químico e mecânico. I. Pereira, Gabriel Kalil Rocha, orientador. II. Título.
CDU: 616.314-18
Dedico este trabalho à minha mãe, meus familiares, meus antepassados e meus nobres amigos.
AGRADECIMENTOS
Gratidão!
A DEUS pela oportunidade de estar cumprindo minha missão também na área profissional.
À Faculdade Meridional (IMED), representada pelo seu Diretor Geral Prof. Dr. Eduardo Capellari, o nosso agradecimento.
À Escola de Odontologia, representada pelo seu Diretor Prof. Mestre Leodinei Lodi, nosso agradecimento.
Ao Programa de Pós-Graduação em Odontologia, representada pela sua Coordenadora Prof. Dra. Graziela Oro Cericato Nunes de Souza, nosso agradecimento.
Ao meu orientador Prof. Dr. Gabriel Kalil Rocha Pereira e co-orientador Prof. Dr. Rafael Sarkis-Onofre pela confiança depositada em mim para enfrentar esse desafio frente aos enormes contratempos; pela orientação e apoio na execução deste trabalho e por todos os ensinamentos que me transmitiram neste período. A todos os demais professores do mestrado, nosso agradecimento.
Ao Professor Ataís Bacchi, colega e amigo pela sua simplicidade e discrição, mas sempre presente e prestativo quando dele precisei no apoio ao bom desenvolvimento do mestrado.
À Professora Juliana Jetelina de Camargo e Professor Ramiro Estacia Silveira, os quais em sua maravilhosa dedicação à profissão, me proporcionaram realizar estágio docente nas clínicas infantil I e II, reforçando a aplicação das evidências cientificas no setor clínico.
À secretaria do mestrado, representada pela funcionária Júlia Fragomeni Bicca. À Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (ARD - FAPERGS) e a Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (no: 88887.162452 / 2017-00 Capes - Brasil).
A minha mãe pelo exemplo humano de ser.
Aos meus demais familiares, pela condição que me dá e sempre deram de correr atrás dos meus sonhos e realizá-los. Em especial aos meus antepassados, que me transmitiram a mais nobre orientação de evolução espiritual e pessoal.
Aos meus nobres amigos, incansáveis em suas palavras de ânimo e superação e no seu carinho e amor diários transmitidos nesses anos de intensa dedicação ao estudo.
Aos colegas de classe: Carla, Elenusa, Gustavo, Kelly, Luíza, Manoela, Pedro, Rafaela, Ricardo, Rodrigo pelos dias de treinamento juntos.
“ É muito melhor ousar grandes empreendimentos, para obter triunfos gloriosos, ainda que com falhas, do que alinhar-se aos pobres de espírito que não se alegram e nem sofrem muito, porque vivem em crepúsculo que não conhece vitória ou derrota”. (Theodore Roosevelt)
NOTAS PRELIMINARES
O projeto de pesquisa relacionado à esta dissertação foi apresentado a banca de qualificação no dia 10 de maio de 2018 e aprovado pela Banca Examinadora composta pelos Professores Doutores Aloísio Oro Spazzin e Ataís Bacchi.
RESUMO
DALLA VALLE, Alânia Agassis do Nascimento. Papel da técnica de preparo
endodôntico na formação e propagação de defeitos dentinarios: revisão sistematica. 2018. 72 f. Dissertação (Mestrado em Odontologia) – Programa de
Pós-Graduação em Odontologia. Faculdade Meridional, Passo Fundo, 2018.
O efeito da técnica de instrumentação endodôntica em relação a iniciação e/ou propagação de microfissuras é uma questão controversa. Esta revisão sistemática teve como objetivo avaliar o papel da técnica de instrumentação endodôntica com diferentes cinemáticas de movimento em tais desfechos. Estudos in vitro comparando a influência de pelo menos duas diferentes técnicas de instrumentação endodôntica na introdução e propagação de microfissuras de dentina foram identificados nas bases de dados PubMed e SCOPUS até 05 de junho de 2018, sem restrição de idioma e período. Dois autores revisaram independentemente todos os títulos e resumos identificados para elegibilidade. Tabelas foram geradas para resumir os estudos incluídos, e estes foram avaliados para risco de viés. Cinquenta e três artigos preencheram nossos critérios de elegibilidade. Os resultados foram classificados de acordo com o método utilizado para avaliação de microfissuras, e a maioria dos estudos que utilizaram tomografias micro-computadorizadas não evidenciaram formação de novas trincas após a técnica de instrumentação. Em geral, quando os métodos de análise eram destrutivos, as técnicas de instrumentação, independentemente da cinemática de movimento induziam formação de microfissuras. Em relação à região do ápice, quando o comprimento de trabalho da instrumentação foi definido como o comprimento total do canal radicular, ou quando 1 mm foi subtraído deste, o risco de início de microfissura foi reduzido. A maioria dos estudos incluídos apresentou baixo risco de viés para todos os domínios avaliados.Técnicas de instrumentação endodôntica seguindo protocolos rígidos não causarão danos à estrutura dentária.
Palavras-chave: Tratamento endodôntico. Tratamento químico e mecânico.
Introdução de defeitos. Formação de microtrincas. Análise de tomografia computadorizada
ABSTRACT
DALLA VALLE, Alânia Agassis do Nasciment Papel da técnica de preparo
endodôntico na formação e propagação de defeitos dentinarios: revisão sistematica. 2018. 72 p. Dissertation (Master degree in Dentistry). Graduate Program
in Dentistry. Meridional Faculty, Passo Fundo, 2018.
The effect of endodontic instrumentation technique and microcrack initiation and/or propagation is a controversial issue. This systematic review aimed to assess the role of endodontic instrumentation technique with different kinematics on such outcomes.
In vitro studies comparing the influence of at least two different endodontic
instrumentation techniques on the initiation and propagation of dentin microcracks were searched in PubMed and SCOPUS up to 05 June 2018 without language and period restriction. Two authors independently reviewed all identified titles and abstracts for eligibility. Tables were generated to summarize the included studies, and the included studies were assessed for bias. Fifty-three articles met our eligibility criteria. The results were classified according to the method used for microcrack evaluation, and most studies that used nmicro-computed tomography to evaluate microcracks showed no formation of new cracks after the instrumentation technique. In general, when the methods were destructive, the instrumentation techniques irrespective of kinematics induced microcrack formation. In relation to the apex region, when the instrumentation working length was set as the total root canal length, or when 1 mm was subtracted, the risk of microcrack initiation reduces. The majority of the included studies had low risk of bias for all domains assessed. Endodontic instrumentation techniques following strict protocols will not cause damage to the dental structure.
Keywords: Endodontic treatment. Chemical and Mechanical treatment. Defect
SUMÁRIO
1. INTRODUÇÃO ... 13
2. OBJETIVO ... 17
3. HIPÓTESE ... 18
4. RELATÓRIO DO TRABALHO DE CAMPO ... 19
4.1 ALTERAÇÕES EXECUTADAS NO PROTOCOLO DURANTE EXECUÇÃO DA REVISÃO SISTEMÁTICA... 19
5. ARTIGO ... 20
6. CONSIDERAÇÕES FINAIS ... 61
1. INTRODUÇÃO
Os conceitos atuais de odontologia restauradora têm demonstrado que a preservação de estrutura dentária é um ponto fundamental para a sobrevivência e longevidade dentária frente a tratamentos restauradores. Neste sentido, considerando a reabilitação de dentes tratados endodonticamente, um dos fatores mais importantes seria o uso de técnicas endodônticas e restauradoras mais conservadoras possíveis e que evitem danos adicionais às estruturas dentárias (SARKIS-ONOFRE et al., 2017).
A terapia endodôntica tem por objetivo a limpeza e modelagem do conduto radicular para proporcionar condições biológicas e mecânicas para restauração de uma condição de saúde do elemento envolvido (SIQUEIRA et al., 1999). Tradicionalmente o preparo endodôntico era realizado através do uso de técnicas manuais, porém as diferentes cinemáticas e instrumentos utilizados evoluíram (YARED, 2008).
No ano de 1988 a liga de níquel-titânio, foi introduzida na endodontia para a confecção de instrumentos inicialmente manuais e posteriormente rotatórios. Observaram que limas manuais níquel-titânio apresentavam uma flexibilidade duas a três vezes maior que os instrumentos de aço inoxidável quando aplicadas forças de curvatura e torção, comportamento este que resultava em resistência superior a fratura por torção tanto quando aplicadas cargas no sentido horário quanto no anti-horário (WALIA et al., 1988).
YARED, em 2008, propôs pela primeira vez o uso de um único instrumento para o preparo do canal radicular por meio do uso de lima rotatórias níquel-titânio ProTaper F2 utilizando movimento reciprocante, o estudo utilizou motor elétrico Italiano ATR que se movimenta 1200 no sentido horário e 300 no sentido inverso. Os resultados mostraram menores índices de fratura, menor tempo de preparo e eficácia no preparo do canal radicular. Motivados por este estudo no ano de 2010, foi lançado no mercado o sistema Reciprocante. Este sistema tem a proposta de trabalhar em movimentação reciprocante, e, é fabricado com uma nova liga niquel-titânio denominada MWire, desenvolvida por um processo especial de tratamento térmico, que proporciona maior flexibilidade e resistência a fadiga cíclica que a liga convencional de niquel-titânio (VILASBOAS et al., 2013).
Outros diversos tipos de sistemas rotatórios estão no mercado: ProTaper (Dentsply Maillefer, Baillagues, Suíça), ProFile (Dentsply Maillefer), Race (FKG Dentaire, La-Chaux-de-Fonds, Switzerland), K3 (Dentsply Maillefer, Ballaigues, Switzerland), o BioRace (FKG Dentaire, La-Chaux-de-Fonds, Switzerland) (FREGNANI; HIZATUGU, 2012).
Destaca-se também sistemas de limas de “uso único” que foram introduzidos no mercado: WaveOne® (Dentsply Tulsa Dental Specialties, Dentsply Maillefer Baillagues, Suíca) e Reciproc® (VDW, Munich, Germany) que são instrumentos reciprocantes fabricados com uma nova liga de níquel-titâno (M-Wire), que proporciona uma ainda maior elasticidade e resistência à fratura que as tradicionais ligas de niquel-titânio, ocorrendo um alívio da tensão sobre o instrumento tornando mais segura sua utilização na rotina clínica, reduzindo o tempo de trabalho (YE e GAO, 2012; ROBINSON et al., 2013).
Também importante sistema introduzido no mercado é o Twisted File Adaptive System (TFA, SybronEndo; Orange, CA, EUA) que de acordo com o fabricante, quando as tensões são impostas ao instrumento TFA dentro do canal, o motor executa um movimento convencional no sentido horário, rotatório, permitindo eficiência de corte e remoção de detritos e quando há o aumento da tensão torcional, o movimento muda automaticamente em um modo reciprocante (VIEIRA et al., 2016).
Outro sistema reciprocante, especialmente utilizado nos casos de canais ovais e achatados, foi lançado no mercado, conhecido como o sistema Self-Adjusting File (SAF) o qual é composto por finas treliças de níquel-titânio recobertas em sua face externa por uma camada de material abrasivo (VILLAGRA, 2014).
Dentes com defeitos dentinários são observados em casos específicos e são potencialmente sintomáticos, sendo esta a razão reportada como o terceiro fator mais prevalente que resulta na perda dentária, superada apenas pelas taxas observadas em relação as doenças cárie e periodontal. As opções de tratamento para dentes endodonticamente comprometidos são comumente longas, de alto custo, e com algum potencial risco de morbidade para o elemento envolvido. Ainda assim, existe pouca evidência definitiva para apoiar o diagnóstico de defeitos dentinários requerendo intervenção ou a eficácia das intervenções (LANDRIGAN et al., 2010).
Estudos relataram que o uso de instrumentos de niquel-titânio provoca defeitos dentinários na dentina radicular (HIN et al., 2013, LIU et al., 2013, ASHWINKUMAR et al., 2014, KARATAS et al., 2016). Isso poderia acontecer devido a instrumentação
rotatória aumentar significativamente a tensão na dentina devido ao maior torque e ao aumento da conicidade proporcionada por estes instrumentos. Além disso, o próprio formato destes poderia contribuir para o aumento da tensão no ápice e concentrações de tensão durante a instrumentação do canal radicular. Assim, quando o instrumento rotatório é submetido alternadamente a forças de flexão, podem-se introduzir defeitos dentinários e, finalmente, fraturas neste substrato dentinário (ASHWINKUMAR et al., 2014).
No estudo de SHEMESH et al., em 2009 foi revelado pela primeira vez que a eficiência da instrumentação rotatória também pode ter um custo biomecânico criando defeitos dentinários. Desde este relato inicial, uma série de estudos sobre esse tema foram publicados corroborando essa afirmação (BIER et al., 2009; SHEMESH et al., 2011; ADORNO et al., 2011; YOLDAS et al., 2012; BARRETO et al., 2012; BURKLEIN et al., 2013; LIU et al., 2013; ASHWINKUMAR et al., 2014; KUMARAN et al., 2013; KANSAL et al., 2014; KARATAS et al., 2015; ABOU EL NASR et al., 2014 e POP et al., 2014). Tais defeitos dentinários poderiam eventualmente se propagar e levar a formação de fraturas na dentina radicular, quanto estes elementos fossem submetidos a função na cavidade oral, levando a perda do elemento dental (KFIR et al., 2017).
No entanto, estudos recentes têm levantado a hipótese de que essa simplificação da técnica (tanto considerando técnicas rotatórias quanto reciprocantes) poderia ter também um custo biomecânico alto, através da formação de defeitos dentinários na dentina radicular, que poderiam eventualmente propagar-se e levar a formação de uma fratura radicular vertical e assim resultar na extração do dente quando este elemento dentário é submetido a função no ambiente oral (DE-DEUS et al., 2014).
Ainda neste sentido, destacam-se que estudos pioneiros para avaliar essa temática baseavam-se em experimentos destrutivos que apresentam uma desvantagem notável relacionada à natureza destes experimentos atuais (não- destrutivos), já que estes eram todos baseados na avaliação óptica, com ou sem o auxílio de lupas cirúrgicas, microscópios, corantes e/ou transiluminação, definindo diferenças na avaliação metodológica dos defeitos dentinários (LANDRIGAN et al., 2010).
Técnicas de microtomografia computadorizada provaram-se úteis em uma ampla variedade de aplicações na pesquisa odontológica tanto para estudos in vitro como in vivo (SWAIN et al., 2009), fornecendo imagens de alta resolução, bem como
permitindo uma análise qualitativa e quantitativa do elemento envolvido (dente, osso e implantes). A microtomografia computadorizada mostrou confiabilidade tão parecida quanto a microscopia ótica na detecção de defeitos dentinários, acrescentando a possibilidade de avaliar todo o tecido dentinário, antes e depois do preparo do canal, e fornecendo uma visualização clara dos defeitos dentinários (DE-DEUS et al., 2016). Em relação aos estudos posteriores que utilizaram técnicas de avaliação por microtomografia computadorizada observa-se comumente que estes rejeitam a associação entre técnicas de instrumentação e inserção de defeitos dentários (BAYRAM et al., 2017; CASSIMIRO et al., 2017; DE OLIVEIRA et al., 2017; DE-DEUS et al.,2015; DE-DEUS et al., 2017., STRINGUETA et al., 2017; ZUOLO et al., 2017). Desta forma nota-se que existe uma ampla divergência na literatura a cerca desta temática o que encoraja a execução de uma revisão sistemática como uma alternativa para compilar e aprofundar o conhecimento científico sobre este tema.
2. OBJETIVO
Esse estudo teve por objetivo avaliar, através de uma revisão sistemática, a influência da técnica de preparo endodôntico e a formação e/ou propagação desses defeitos dentinários, levando em consideração o tipo de análise utilizada na detecção desses defeitos dentinários.
3. HIPÓTESE
Com base na falta de consenso apresentada na literatura a cerca desta temática adotamos uma hipótese nula onde técnicas de instrumentação endodôntica não atuariam na formação e/ou propagação dos defeitos e/ou de defeitos dentinários.
4. RELATÓRIO DO TRABALHO DE CAMPO
4.1 ALTERAÇÕES EXECUTADAS NO PROTOCOLO DURANTE EXECUÇÃO DA REVISÃO SISTEMÁTICA
Tendo em vista a alta heterogeneidade de metodologias empregadas nos diferentes estudos incluídos e as diferentes formas de reporte dos resultados utilizadas, a extração de dados referentes a percentagem total de micro-cracks identificados e a percentagem por grupo testado se mostrou inviável, de mesma forma estes fatores inviabilizaram o uso de metodologias quantitativas com base em meta-analises para qualquer desfecho e o acesso do potencial de viés de publicação observado. Portanto, foram executadas análises descritivas apenas dos resultados observados.
5. ARTIGO
Title: Influence of root canal preparation technique on the initiation and propagation of dentinal microcracks: a systematic review.
Authors A.D. Valle1 L. Dotto2 R.D. Morgental3 T. Pereira-Cenci4 G.K.R. Pereira1,3 R. Sarkis-Onofre1,4
1 Graduate Program in Dentistry, Meridional Faculty/IMED, Passo Fundo, Brazil 2 Meridional Center of Dental Studies/CEOM, Passo Fundo, Brasil
3 Graduate Program in Dentistry, Federal University of Santa Maria, Santa Maria, Brazil 4 Graduate Program in Dentistry, Federal University of Pelotas, Pelotas, Brazil
Running title: Root preparation and microcracks
Keywords: Endodontic treatment; dentinal microcracks; micro-computed tomography
analysis; root canal preparation; systematic review.
Corresponding author Dr. Rafael Sarkis-Onofre
Graduate Program in Dentistry, Meridional Faculty/IMED, 304, Senador Pinheiro Street, Passo Fundo, Brazil
Abstract
Background: The effect of root canal preparation technique on microcrack initiation and/or
propagation is a controversial issue.
Aim: This systematic review aimed to assess the role of root canal preparation techniques with
different kinematics (manual, rotary, reciprocating, adaptive, self-adjusting file) on such outcomes.
Data sources: Studies were identified by searching two electronic databases
(PubMed/MEDLINE and SCOPUS) without language and period restriction.
Study eligibility criteria, participants, and interventions: In vitro studies comparing the
influence of at least two different root canal preparation techniques on the initiation and propagation of dentin microcracks were searched Two authors independently reviewed all identified titles and abstracts for eligibility.
Study appraisal and synthesis methods: Tables were generated to summarize the included
studies, and the included studies were assessed for bias based on previous studies.
Results: Fifty-three (53) articles met the eligibility criteria. The results were classified
according to the method used for microcrack evaluation, and most studies that used micro-computed tomography showed no formation of new cracks after root canal preparation. In general, the instrumentation techniques induced microcrack formation when the methods were destructive, irrespective of kinematics. In relation to the apex region, when the preparation working length was set as the root canal length subtracted of 1 mm, the risk of microcrack initiation reduces. The majority of the included studies had low risk of bias for all assessed domains.
Conclusion: Root canal preparation following strict protocols will not cause damage to the
dental structure.
Introduction
Hand root canal preparation techniques were successfully employed for many years, with advances (e.g. nickel–titanium instruments) leading to alternative mechanized systems that employ different kinematics, optimizing the procedure, enhancing shaping ability and decreasing the risk of instrument fracture during treatment (Walia et al. 1988; Thompson 2000). Kinematics of engine-driven Ni-Ti instruments may be divided into rotary motion, rotational reciprocating motion, vertical vibration (vibrations on in-and-out motion for self-adjusting files), and rotary motion plus rotational reciprocating motion (adaptive motion) (Capar & Arslan 2016). Considering that these systems are operated under different kinematics and
parameters of use, these factors may potentially influence the efficacy of the instrumentation and its impact on the final performance of endodontically treated teeth. Recent studies suggested that mechanized instruments may present an increased biological cost leading to additional tooth structure removal and also inducing the formation and propagation of microcracks on dentinal root canal surface (Yoldas et al. 2012; Kfir et al. 2017; Pedulla et al. 2017).
It is known that a higher frequency of defects in a material exponentially increases the risk of stress concentration during mechanical loading and potentially impairs the mechanical performance of the restorative assembly leading to catastrophic fracture under lower loads than the conventional nominal resistance (Griffith 1921), and that microcracks induced by different root canal preparation techniques could compromise tooth mechanical performance during masticatory function (Missau et al. 2017). In contrast, many studies refute any causal relation between different preparation techniques and microcrack formation/propagation (De-Deus et
al. 2015; De-Deus et al. 2017; Stringheta et al. 2017; Zuolo et al. 2017). The existing high
heterogeneity of methodological aspects involved in the different in vitro studies together with the heterogeneity of various existing techniques, kinematics and parameters of use contributes to this lack of consensus.
There are two major fundamental methodologies to assess the presence of defects/microcracks on tooth structure. The first is based on destructive tests, where teeth are first visually inspected for the presence of defects, then instrumented; next, slices are made, and each slice is individually analyzed considering the presence or absence of defects (Yoldas et al. 2012; Kfir et al. 2017; Pedulla et al. 2017). Studies using this approach frequently use non-instrumented teeth as the baseline comparison condition, and it is possible that such a processing technique could induce defects (Swain & Xue 2009; Stringheta et al. 2017). The second approach is based on non-destructive techniques, usually employing micro-computed tomography (µCT) analysis, where the teeth are initially scanned for microcracks and are rescanned after instrumentation, and then the images superposed, which grants considerably higher accuracy, precision and more reliable data (Swain & Xue 2009; De-Deus et al. 2015; De-Deus et al. 2017; Stringheta et al. 2017; Zuolo et al. 2017). Thus, this systematic review aimed to assess the role of endodontic instrumentation techniques with different kinematics on microcrack initiation and/or propagation. In addition, we discussed the accuracy and validity for microcrack detection of the different implemented methods.
This systematic review followed the 4-phase flow diagram in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement (Moher et al. 2009) and the review report is based on the PRISMA Statement checklist (Moher et al. 2009).
Registration
We did not pre-register the methods of our systematic review of in vitro studies, as we are unaware of any registered research of this nature.
Eligibility criteria Inclusion criteria
We included published in vitro studies comparing the influence of at least two different root canal preparation techniques (manual, rotary, reciprocating, adaptive, self-adjusting file) on the initiation and propagation of dentin microcracks in teeth and evaluating the quantity and/or length of microcracks. We included studies independent of the implemented microcrack evaluation technique (destructive or non-destructive), the group of teeth evaluated or the definition of the presence or not of cracks. No language and publication date restrictions were imposed.
Exclusion criteria
We excluded articles reporting clinical evaluations and narrative/systematic reviews.
Information sources and search
Studies were identified by searching two electronic databases (PubMed/MEDLINE and SCOPUS) without language and period restriction. The search strategy was drafted based on the MeSH terms of PubMed/MEDLINE and related entry terms. Adapted terms were necessary for searching the SCOPUS database (Supplemental Material 1). The last search was run on 05 June 2018. Additionally, a manual search was performed in two endodontic journals (Journal of Endodontics and International Endodontic Journal) considering articles published in the last two years.
Study selection
Results of the literature searches were uploaded in the Endnote program (Thomson Reuters, New York, NY) and duplicate records were removed. Two reviewers independently screened all titles and abstracts and full-text copies of all studies that met the inclusion criteria
or were classified as uncertain (when there was insufficient information in the title/abstract). The same two reviewers independently assessed the full-text copies and the discrepancies were resolved through discussion between the reviewers. A third reviewer was consulted in case of disagreement.
Data collection process and Data items
We developed a standardized outline to extract the following data: Publication details: author, year of publication;
Endodontic treatment details: tested endodontic instrumentation techniques, substance used for root irrigation.
Methodological details: dental group, methodology used for microcrack evaluation, if that technique was based on a destructive or non-destructive method, and evaluation time (before and/or after root canal instrumentation).
Main findings.
All data items were initially discussed among four reviewers involved in the study and the data collection process was completed by 2 independent reviewers and verified by two others independently.
Risk of bias assessment
We assessed the risk of bias of included studies based on previous studies (Sarkis-Onofre et al. 2014; Isolan et al. 2018) and considering the judgment of the following items: teeth randomization, use of teeth with similar anatomy, blinding of microcracks assessment, independent microcracks assessment and care with maintenance of dental humidity. All data items were discussed among three reviewers and the ratings (unclear, high risk and low risk of bias) were completed by one member of the team and verified by another two members independently. Publication bias was not statistically assessed.
Data Synthesis
The primary outcome was the number of new microcracks observed after the root canal preparation only considering studies evaluating microcracks formation through micro-computed tomography. We decided to use that outcome because previous studies demonstrated that the use of destructive methods could introduce new microcracks during sample preparation (Swain & Xue 2009; Stringheta et al. 2017; Zuolo et al. 2017). However, a meta-analysis was
not possible based on the heterogeneity of the research designs. As such, studies were synthesized descriptively, and tables were separated by microcrack assessment method.
The data presented on the studies that used destructive methods were collected and synthesized descriptively as complementary data. Another important aspect is that some studies focused on the initiation and propagation of cracks on the external surface of apex teeth region, and those studies were also considered separately.
Results
Literature search
One hundred sixteen (116) of the 937 titles and abstracts screened were selected for full-text analysis, with 63 studies excluded and 53 studies meeting our eligibility criteria (Figure 1). The reasons for exclusion are reported in Figure 1 (Adorno et al. 2009; Bier et al. 2009; Adorno
et al. 2010; Milani et al. 2012; Yoldas et al. 2012; Burklein et al. 2013; Hin et al. 2013; Liu et al. 2013; Liu et al. 2013; Abou El Nasr & Abd El Kader 2014; Arias et al. 2014; Ashwinkumar et al. 2014; Kansal et al. 2014; Priya et al. 2014; Aydin et al. 2015; Çiçek et al. 2015; De-Deus et al. 2015; Garg et al. 2015; Helvacioglu-Yigit et al. 2015; Jalali et al. 2015; Karatas et al.
2015; Karatas et al. 2015; Karatas et al. 2015; Li et al. 2015; Monga et al. 2015; Pop et al. 2015; Rose & Svec 2015; Shori et al. 2015; Ustun et al. 2015; Zhou et al. 2015; Ceyhanli et al. 2016; Coelho et al. 2016; Kumari & Krishnaswamy 2016; Topçuoğlu et al. 2016; Bahrami et
al. 2017; Bayram et al. 2017; Cassimiro et al. 2017; de Oliveira et al. 2017; De-Deus et al.
2017; Devale et al. 2017; Harandi et al. 2017; Jain et al. 2017; Kesim et al. 2017; Kfir et al. 2017; Khirtika & Ramesh 2017; Pedulla et al. 2017; Saha et al. 2017; Stringheta et al. 2017; Zuolo et al. 2017; Borges et al. 2018; Cassimiro et al. 2018; Khoshbin et al. 2018; Li et al. 2018).
Study characteristics
Supplemental material 2 presents the characteristics of the included studies. Sixteen (16) studies (30.2%) compared rotary and reciprocating preparation techniques (Burklein et al. 2013; Abou El Nasr & Abd El Kader 2014; Kansal et al. 2014; Jalali et al. 2015; Karatas et al. 2015; Li et al. 2015; Pop et al. 2015; Ceyhanli et al. 2016; Coelho et al. 2016; Topçuoğlu et al. 2016; Cassimiro et al. 2017; De-Deus et al. 2017; Harandi et al. 2017; Pedulla et al. 2017; Stringheta et al. 2017; Cassimiro et al. 2018), 12 (20.6%) compared manual, rotary and reciprocating techniques (Bier et al. 2009; Ashwinkumar et al. 2014; Priya et al. 2014; Çiçek
Oliveira et al. 2017; Borges et al. 2018; Khoshbin et al. 2018; Li et al. 2018) and 8 studies (17%) tested manual and rotary techniques (Adorno et al. 2009; Adorno et al. 2010; Milani et
al. 2012; Liu et al. 2013; Garg et al. 2015; Shori et al. 2015; Kumari & Krishnaswamy 2016;
Devale et al. 2017; Jain et al. 2017). The most commonly used irrigating solutions were 2.5% sodium hypochlorite (n=14) (Yoldas et al. 2012; Abou El Nasr & Abd El Kader 2014; Ashwinkumar et al. 2014; Aydin et al. 2015; Çiçek et al. 2015; Jalali et al. 2015; Ustun et al. 2015; Ceyhanli et al. 2016; Topçuoğlu et al. 2016; Cassimiro et al. 2017; De-Deus et al. 2017; Saha et al. 2017; Stringheta et al. 2017; Cassimiro et al. 2018) and 1% sodium hypochlorite (n=13) (Adorno et al. 2009; Adorno et al. 2010; Milani et al. 2012; Kansal et al. 2014; Priya et
al. 2014; Li et al. 2015; Pop et al. 2015; Zhou et al. 2015; Bayram et al. 2017; de Oliveira et al. 2017; Kesim et al. 2017; Khirtika & Ramesh 2017; Borges et al. 2018). Mandibular incisors
were used in 17 studies (32.1%) (Milani et al. 2012; Burklein et al. 2013; Liu et al. 2013; Liu
et al. 2013; Arias et al. 2014; Priya et al. 2014; Helvacioglu-Yigit et al. 2015; Karatas et al.
2015; Ustun et al. 2015; Cassimiro et al. 2017; de Oliveira et al. 2017; Khirtika & Ramesh 2017; Pedulla et al. 2017; Zuolo et al. 2017; Cassimiro et al. 2018) and mandibular premolars in 15 studies (28.3%) (Adorno et al. 2009; Bier et al. 2009; Adorno et al. 2010; Hin et al. 2013; Kansal et al. 2014; Aydin et al. 2015; Garg et al. 2015; Jalali et al. 2015; Monga et al. 2015; Bayram et al. 2017; Devale et al. 2017; Jain et al. 2017; Kesim et al. 2017; Kfir et al. 2017; Saha et al. 2017). Most studies (n=38) used destructive techniques for microcracks evaluation (Bier et al. 2009; Milani et al. 2012; Yoldas et al. 2012; Burklein et al. 2013; Hin et al. 2013; Liu et al. 2013; Liu et al. 2013; Abou El Nasr & Abd El Kader 2014; Arias et al. 2014; Ashwinkumar et al. 2014; Kansal et al. 2014; Priya et al. 2014; Aydin et al. 2015; Çiçek et al. 2015; Garg et al. 2015; Helvacioglu-Yigit et al. 2015; Jalali et al. 2015; Karatas et al. 2015; Karatas et al. 2015; Karatas et al. 2015; Li et al. 2015; Monga et al. 2015; Rose & Svec 2015; Shori et al. 2015; Ustun et al. 2015; Coelho et al. 2016; Bahrami et al. 2017; Harandi et al. 2017; Jain et al. 2017; Kesim et al. 2017; Kfir et al. 2017; Khirtika & Ramesh 2017; Pedulla et
al. 2017; Saha et al. 2017; Zuolo et al. 2017; Borges et al. 2018; Cassimiro et al. 2018;
Khoshbin et al. 2018). Twenty-nine (29) studies (54.7%) evaluated the microcracks using a stereomicroscope (Bier et al. 2009; Yoldas et al. 2012; Burklein et al. 2013; Hin et al. 2013; Liu et al. 2013; Abou El Nasr & Abd El Kader 2014; Kansal et al. 2014; Priya et al. 2014; Aydin et al. 2015; Garg et al. 2015; Helvacioglu-Yigit et al. 2015; Jalali et al. 2015; Karatas et
al. 2015; Karatas et al. 2015; Karatas et al. 2015; Li et al. 2015; Monga et al. 2015; Shori et al.
2015; Ustun et al. 2015; Kumari & Krishnaswamy 2016; Topçuoğlu et al. 2016; Devale et al. 2017; Harandi et al. 2017; Jain et al. 2017; Kesim et al. 2017; Pedulla et al. 2017; Borges et al.
2018; Cassimiro et al. 2018; Khoshbin et al. 2018) and only 10 studies (20.7%) used the µCT (De-Deus et al. 2015; Pop et al. 2015; Ceyhanli et al. 2016; Bayram et al. 2017; Cassimiro et
al. 2017; de Oliveira et al. 2017; De-Deus et al. 2017; Stringheta et al. 2017; Zuolo et al. 2017;
Li et al. 2018).
Micro-computed tomography studies
Table 1 features the results of studies that used µCT to evaluate the microcracks (n=10). Seven studies demonstrated no formation of new cracks after root canal preparation (De-Deus
et al. 2015; Bayram et al. 2017; Cassimiro et al. 2017; de Oliveira et al. 2017; De-Deus et al.
2017; Stringheta et al. 2017; Zuolo et al. 2017), and the following studies revealed formation of new cracks after root canal preparation: Li et al. (Li et al. 2018) showed that the OneShape system (rotary system) resulted in increased microcracks; Ceyhanli et al. (Ceyhanli et al. 2016) compared two rotary systems (ProTaper Universal and RaCe) and one reciprocating system (Safesider) and the results revealed that all systems increased the number of microcracks, and ProTaper Universal generated more microcracks than the RaCe system; Pop et al., (Pop et al. 2015) tested ProTaper Universal (rotary) and WaveOne (reciprocating) and both systems induced microcracks.
Destructive methods
Table 2 features the results of the studies that used destructive methodologies to evaluate the microcrack initiation (n=38) (Bier et al. 2009; Milani et al. 2012; Yoldas et al. 2012; Burklein et al. 2013; Hin et al. 2013; Liu et al. 2013; Liu et al. 2013; Abou El Nasr & Abd El Kader 2014; Arias et al. 2014; Ashwinkumar et al. 2014; Kansal et al. 2014; Priya et al. 2014; Aydin et al. 2015; Çiçek et al. 2015; Garg et al. 2015; Helvacioglu-Yigit et al. 2015; Jalali et
al. 2015; Karatas et al. 2015; Karatas et al. 2015; Karatas et al. 2015; Li et al. 2015; Monga et al. 2015; Rose & Svec 2015; Shori et al. 2015; Ustun et al. 2015; Coelho et al. 2016; Bahrami et al. 2017; Harandi et al. 2017; Jain et al. 2017; Kesim et al. 2017; Kfir et al. 2017; Khirtika
& Ramesh 2017; Pedulla et al. 2017; Saha et al. 2017; Zuolo et al. 2017; Borges et al. 2018; Cassimiro et al. 2018; Khoshbin et al. 2018). In summary, the majority of these studies induced microcrack formation (23 studies in an undeniable way, 11 in a partial way, where some specific kinematics did not induce microcracks), thus only four studies rejected the hypothesis of microcrack initiation through root canal preparation (Arias et al. 2014; Rose & Svec 2015; Coelho et al. 2016; Bayram et al. 2017).
It is important to highlight that among these four studies that rejected the influence of root canal instrumentation, Coelho et al. (Coelho et al. 2016) did not observe microcracks formation after all instrumentation kinematics considered (Profile on rotary motion, TRUShape on rotary motion and WaveOne Gold on reciprocating motion), while Arias et al. (Arias et al. 2014) (considering Profile GT by hand motion, WaveOne on reciprocating motion) and Bahrami et al. (Bahrami et al. 2017) (considering Stainless steel K-Flexo files by hand motion, TRUShape on rotary motion, WaveOne Gold on reciprocating motion) observed absence of any defect and Rose & Svec did not observe microcrack formation considering WaveOne on reciprocating motion, ProTaper on rotatory motion and GT files by hand motion (Rose & Svec 2015).
Among the studies that partially support an instrumentation technique influence, hand (Bier et al. 2009; Yoldas et al. 2012; Çiçek et al. 2015; Garg et al. 2015; Monga et al. 2015; Ustun et al. 2015; Khoshbin et al. 2018), SAF (Yoldas et al. 2012; Liu et al. 2013; Kfir et al. 2017) or TFA (Zhou et al. 2015) kinematics were the employed techniques when no microcracks were observed. Moreover, Bier et al. (Bier et al. 2009) observed the use of a rotary instrument which did not induce microcracks (S-ApeX system), whereas the use of ProTaper, ProFile and SystemGT all on rotary motion lead to microcrack initiation.
Apex region
Table 3 features the results of the studies that considered the external apex region of teeth instrumented under different kinematics (n=9) (Adorno et al. 2009; Adorno et al. 2010; Liu et al. 2013; Liu et al. 2013; Rose & Svec 2015; Zhou et al. 2015; Kumari & Krishnaswamy 2016; Topçuoğlu et al. 2016; Devale et al. 2017). Five of these studies compared hand and rotary instrumentation (Adorno et al. 2009; Adorno et al. 2010; Liu et al. 2013; Kumari & Krishnaswamy 2016; Devale et al. 2017); one compared hand and rotary and reciprocating (Rose & Svec 2015); one compared rotary and reciprocating (Topçuoğlu et al. 2016); one compared rotary, reciprocating and TFA (Zhou et al. 2015); and one rotary, reciprocating and SFA (Liu et al. 2013).
In summary, these types of in vitro studies showed a positive relationship between instrumentation and defect introduction (irrespective of the employed kinematics - 7 supported microcrack formation (Adorno et al. 2009; Adorno et al. 2010; Liu et al. 2013; Zhou et al. 2015; Kumari & Krishnaswamy 2016; Topçuoğlu et al. 2016; Devale et al. 2017), 1 only showed one system (Liu et al. 2013) (Protaper on rotary motion), and 1 completely discarded
microcrack formation for any system (Rose & Svec 2015) (considering Profile GT on hand motion, ProTaper Universal on rotary motion and WaveOne on reciprocating motion).
Another important factor considered in the majority of these studies was the working length (WL) for instrumentation; only Liu et al. (2013), Topçuoglu et al., 2016 and Rose & Svec (2015) did not consider this factor (Liu et al. 2013; Rose & Svec 2015; Topçuoğlu et al. 2016). It seems consensual that when WL is set on total root canal length (RCL) or over this measurement the risk of microcrack initiation is increased, while when at least 1 mm WL for instrumentation is subtracted from the RCL the potential for microcrack initiation is decreased, irrespective of instrument kinematics. The only exception noticed was in Devale et al. (2017), wherein the WL set on RCL and RCL-1mm depicted similar microcrack formation using hand instruments, although they also depicted a significant decrease in such occurrence for the other considered systems (Race and K3 rotary instruments) (Devale et al. 2017).
Risk of bias
The majority of the included studies had a low risk of bias with regard to the following items: teeth randomization (66.1%), blinding of outcome assessment (54.7%), independent assessment (58.5%) and control of teeth moisture (96.2%), and all studies presented low risk of bias with regard to using teeth with similar anatomy (Figure 2). The review of the authors’ judgments on each risk of bias item for each included study are presented in Supplemental Material 3.
Discussion
Our systematic review is the first to our knowledge that synthesizes all studies assessing the influence of different root canal preparation techniques on microcrack initiation, and/or propagation in endodontically treated teeth. Clear evidence was found refuting any alleged influence of root canal preparation leading to microcrack initiation and/or propagation, as the majority of studies that used a reliable and accurate methodology showed no relationship between these factors.
The lack of consensus on the effect of the instrumentation technique on microcrack development was mainly motivated by the influence of the evaluation methods acting as confounders (Stringheta et al. 2017). Destructive methodologies such as stereomicroscope demonstrated that root canal preparation techniques lead to microcracks formation that were not present before the instrumentation (Stringheta et al. 2017). In contrast, studies using µCT analysis demonstrated no new microcrack formation after root canal preparation (De-Deus et
al. 2015; Bayram et al. 2017; Cassimiro et al. 2017; de Oliveira et al. 2017; De-Deus et al.
2017; Stringheta et al. 2017; Zuolo et al. 2017). The reason why this difference occurs is that µCT is the most reliable and accurate method.
A recent systematic review (Wei et al. 2017) evaluating the incidence of dentinal microcracks during the use of reciprocating and rotatory systems considering only destructive methods (teeth sectioned and examined with stereomicroscope or scanning electron microscopy - SEM) demonstrated that the ProTaper technique resulted in more dentinal microcracks compared to other systems. However, the problems related to the use of destructive techniques are that they do not consider the potential injury caused by the single interplay of different sources of stress on root canal dentin in the different treatment moments. Issues such as the effect of the NaOCl substance used during irrigation, the mechanical preparation itself, the sectioning methodology (Stringheta et al. 2017), the inherent dehydration caused by the difficulty of maintaining of an adequate condition during the time spent in executing such methodology (Shemesh et al. 2018), and the mandatory alcohol series dehydration that precedes scanning electron microscopy analysis are not considered. Also, destructive methods only allow assessing limited levels of the root canal length (Stringheta et al. 2017).
Micro-computed tomography analysis assesses all of the root canal length, allowing the accurate positioning of dentinal microcracks. The three-dimensional reconstruction can be performed at different stages of endodontic treatment permitting that the pre-existing microcracks can be observed as it is a non-destructive method (Swain & Xue 2009; De-Deus
et al. 2016). In regards to the effect of dehydration on microcrack initiation, Shemesh et al.
(Shemesh et al. 2018) states that even studies which use µCT analysis are susceptible to be biased/confounded by such a factor. In this sense, it may be highlighted that almost all studies included in the present systematic review allegedly took precautions to maintain teeth hydration.
Three studies using µCT (Pop et al. 2015; Ceyhanli et al. 2016; Li et al. 2018) demonstrated that instrumentation systems increased the number of microcracks. The variation of results could be associated to differences in the methodological aspects, the quality of tool used and the familiarity of the operator with hand techniques. For example, De-Deus et al. (De-Deus et al. 2016) pointed out several aspects that could interfere in the results of the study by Ceyhanli et al. 2016; only 10 sections of each specimen were evaluated (<1.5% of the total of obtained images) which did not permit the evaluating all of the root canal length; the results could be related to false-positive findings because the used method did not permit distinction
between microcracks and artefact/noise; and details about scanning and reconstruction were not reported, thus making it difficult to reproduce the study.
Another important consideration is the influence of the working length set for root canal preparation, irrespective of the implemented technique. Studies are almost unanimous that the subtraction of 1 mm to the root canal length should be performed to avoid damage (microcrack initiation/propagation) to the apex region, for all considered preparation techniques. However, a report of microcrack formation absence in the apex region exists in the literature and yet remains to be tested; i.e. the influence that the surrounding tissues may exert on teeth during instrumentation. Rose and Svec, was the only study that used a methodological approach where teeth were instrumented still attached to hemisected jaws under preservation of whole surrounding tissues, and this was the main reason claimed by the authors to explain the absence of any microcracks in any evaluated system (Rose & Svec 2015).
Strengths of our study include rigorous methods for study selection and data extraction including the risk of bias assessment. Also, most included studies presented low risk of bias in all domains. As a limitation of the present study, assessment of the impact of publication bias in the results of the systematic review was not possible. Although it seems clear that the root canal preparation technique is probably not related to microcrack development, the impact of various restorative strategies in the propagation of microcracks detected in pre-endodontic treatment and its behavior remains largely unknown. Also, the compliance of strict protocols from tooth extraction until final analysis should be taken and completely reported when published.
Conclusion
In conclusion, our results seem to indicate that the various root canal preparation techniques considered in this study will not cause damage to the dental structure when adequately employed.
Acknowledgments
The study is funded by a grant from the Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul (ARD – FAPERGS). RSO and GKRP are funded in part by Meridional Foundation (Passo Fundo – Brazil) and RSO in part by Coordination for the Improvement of Higher Education Personnel (no: 88887.162452/2017-00 Capes – Brazil), TPC is partially founded by National Council for Scientific and Technological Development (CNPq - Brazil).
The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript.
The authors deny any conflicts of interest related to this study.
References
Abou El Nasr HM, Abd El Kader KG (2014) Dentinal damage and fracture resistance of oval roots prepared with single-file systems using different kinematics. Journal of Endodontics 40, 849-851.
Adorno CG, Yoshioka T, Suda H (2009) The effect of root preparation technique and instrumentation length on the development of apical root cracks. Journal of Endodontics 35, 389-392.
Adorno CG, Yoshioka T, Suda H (2010) The effect of working length and root canal preparation technique on crack development in the apical root canal wall. International Endodontic Journal 43, 321-327.
Arias A, Lee YH, Peters CI, Gluskin AH, Peters OA (2014) Comparison of 2 canal preparation techniques in the induction of microcracks: a pilot study with cadaver mandibles. Journal of Endodontics 40, 982-985.
Ashwinkumar V, Krithikadatta J, Surendran S, Velmurugan N (2014) Effect of reciprocating file motion on microcrack formation in root canals: An SEM study. International Endodontic Journal 47, 622-627.
Aydin U, Aksoy F, Karataslioglu E, Yildirim C (2015) Effect of ethylenediaminetetraacetic acid gel on the incidence of dentinal cracks caused by three novel nickel-titanium systems. Aust Endod J 41, 104-110.
Bahrami P, Scott R, Galicia JC, Arias A, Peters OA (2017) Detecting Dentinal Microcracks Using Different Preparation Techniques: An In Situ Study with Cadaver Mandibles. Journal of Endodontics 43, 2070-2073.
Bayram HM, Bayram E, Ocak M, Uygun AD, Celik HH (2017) Effect of ProTaper Gold, Self-Adjusting File, and XP-endo Shaper Instruments on Dentinal Microcrack Formation: A Micro–computed Tomographic Study. Journal of Endodontics 43, 1166-1169.
Bier CA, Shemesh H, Tanomaru-Filho M, Wesselink PR, Wu MK (2009) The ability of different nickel-titanium rotary instruments to induce dentinal damage during canal preparation. Journal of Endodontics 35, 236-238.
Borges AH, Damiao MS, Pereira TM, Filho GS, Miranda-Pedro FL, Luiz de Oliveira da Rosa W et al. (2018) Influence of Cervical Preflaring on the Incidence of Root Dentin Defects. Journal of Endodontics 44, 286-291.
Burklein S, Tsotsis P, Schafer E (2013) Incidence of dentinal defects after root canal preparation: reciprocating versus rotary instrumentation. Journal of Endodontics 39, 501-504.
Capar ID, Arslan H (2016) A review of instrumentation kinematics of engine-driven nickel-titanium instruments. Int Endod J 49, 119-135.
Cassimiro M, Romeiro K, Gominho L, de Almeida A, Costa L, Albuquerque D (2017) Occurence of dentinal defects after root canal preparation with R-phase, M-Wire and Gold Wire instruments: a micro-CT analysis. BMC Oral Health 17, 93.
Cassimiro M, Romeiro K, Gominho L, de Almeida A, Silva L, Albuquerque D (2018) Effects of Reciproc, ProTaper Next and WaveOne Gold on Root Canal Walls: A Stereomicroscope Analysis. Iran Endod J 13, 228-233.
Ceyhanli KT, Erdilek N, Tatar I, Celik D (2016) Comparison of ProTaper, RaCe and Safesider instruments in the induction of dentinal microcracks: a micro-CT study. International Endodontic Journal 49, 684-689.
Çiçek E, Koçak MM, Saʇlam BC, Koçak S (2015) Evaluation of microcrack formation in root canals after instrumentation with different NiTi rotary file systems: A scanning electron microscopy study. Scanning 37, 49-53.
Coelho MS, Card SJ, Tawil PZ (2016) Light-emitting Diode Assessment of Dentinal Defects after Root Canal Preparation with Profile, TRUShape, and WaveOne Gold Systems. Journal of Endodontics 42, 1393-1396.
de Oliveira BP, Camara AC, Duarte DA, Heck RJ, Antonino ACD, Aguiar CM (2017) Micro-computed Tomographic Analysis of Apical Microcracks before and after Root Canal Preparation by Hand, Rotary, and Reciprocating Instruments at Different Working Lengths. Journal of Endodontics 43, 1143-1147.
De-Deus G, Belladonna FG, Silva EJ, Souza EM, Versiani MA (2016) Critical appraisal of some methodological aspects of using micro-CT technology in the study of dentinal microcracks in endodontics. Int Endod J 49, 216-219.
De-Deus G, Belladonna FG, Souza EM, Silva EJ, Neves Ade A, Alves H et al. (2015) Micro-computed Tomographic Assessment on the Effect of ProTaper Next and Twisted File Adaptive Systems on Dentinal Cracks. Journal of Endodontics 41, 1116-1119.
De-Deus G, Cesar de Azevedo Carvalhal J, Belladonna FG, Silva E, Lopes RT, Moreira Filho RE et al. (2017) Dentinal Microcrack Development after Canal Preparation: A Longitudinal in Situ Micro-computed Tomography Study Using a Cadaver Model. Journal of Endodontics 43, 1553-1558.
Devale MR, Mahesh MC, Bhandary S (2017) Effect of instrumentation length and instrumentation systems: Hand versus rotary files on apical crack formation – an in vitro study. Journal of Clinical and Diagnostic Research 11, ZC15-ZC18.
Garg S, Mahajan P, Thaman D, Monga P (2015) Comparison of dentinal damage induced by different nickel-titanium rotary instruments during canal preparation: An in vitro study. J Conserv Dent 18, 302-305.
Griffith AA (1921) The Phenomena of Rupture and Flow in Solids. Philosophical Transactions of the Royal Society of London. Series A, Containing Papers of a Mathematical or Physical Character 221, 163-198.
Harandi A, Mirzaeerad S, Mehrabani M, Mahmoudi E, Bijani A (2017) Incidence of Dentinal Crack after Root Canal Preparation by ProTaper Universal, Neolix and SafeSider Systems. Iran Endod J 12, 432-438.
Helvacioglu-Yigit D, Aydemir S, Yilmaz A (2015) Evaluation of dentinal defect formation after root canal preparation with two reciprocating systems and hand instruments: an in vitro study. Biotechnol Biotechnol Equip 29, 368-373.
Hin ES, Wu MK, Wesselink PR, Shemesh H (2013) Effects of self-adjusting file, Mtwo, and ProTaper on the root canal wall. Journal of Endodontics 39, 262-264.
Isolan CP, Sarkis-Onofre R, Lima GS, Moraes RR (2018) Bonding to Sound and Caries-Affected Dentin: A Systematic Review and Meta-Analysis. J Adhes Dent 20, 7-18. Jain A, Bhadoria K, Choudhary B, Patidar N (2017) Comparison of dentinal defects induced
by hand files, multiple, and single rotary files: A stereomicroscopic study. World Journal of Dentistry 8, 45-48.
Jalali S, Eftekhar B, Paymanpour P, Yazdizadeh M, Jafarzadeh M (2015) Effects of Reciproc, Mtwo and ProTaper Instruments on Formation of Root Fracture. Iran Endod J 10, 252-255.
Kansal R, Rajput A, Talwar S, Roongta R, Verma M (2014) Assessment of dentinal damage during canal preparation using reciprocating and rotary files. Journal of Endodontics 40, 1443-1446.
Karatas E, Arslan H, Alsancak M, Kirici DO, Ersoy I (2015) Incidence of Dentinal Cracks after Root Canal Preparation with Twisted File Adaptive Instruments Using Different Kinematics. Journal of Endodontics 41, 1130-1133.
Karatas E, Gunduz HA, Kirici DO, Arslan H (2015) Incidence of dentinal cracks after root canal preparation with ProTaper Gold, Profile Vortex, F360, Reciproc and ProTaper Universal instruments. International Endodontic Journal.
Karatas E, Gunduz HA, Kirici DO, Arslan H, Topcu MC, Yeter KY (2015) Dentinal crack formation during root canal preparations by the twisted file adaptive, ProTaper Next, ProTaper Universal, and WaveOne instruments. Journal of Endodontics 41, 261-264. Kesim B, Sagsen B, Aslan T (2017) Evaluation of dentinal defects during root canal preparation
using thermomechanically processed nickel-titanium files. Eur J Dent 11, 157-161. Kfir A, Elkes D, Pawar A, Weissman A, Tsesis I (2017) Incidence of microcracks in maxillary
first premolars after instrumentation with three different mechanized file systems: a comparative ex vivo study. Clin Oral Investig 21, 405-411.
Khirtika SG, Ramesh S (2017) Comparative evaluation of dentinal cracks and detachments after instrumentation with hand and rotary files at various instrumentation lengths: An in vitro study. Journal of Advanced Pharmacy Education and Research 7, 236-239. Khoshbin E, Donyavi Z, Abbasi Atibeh E, Roshanaei G, Amani F (2018) The Effect of Canal
Preparation with Four Different Rotary Systems on Formation of Dentinal Cracks: An In Vitro Evaluation. Iran Endod J 13, 163-168.
Kumari MR, Krishnaswamy MM (2016) Comparative Analysis of Crack Propagation in Roots with Hand and Rotary Instrumentation of the Root Canal -An Ex-vivo Study. J Clin Diagn Res 10, Zc16-19.
Li ML, Liao WL, Cai HX (2018) A micro-computed tomographic evaluation of dentinal microcrack alterations during root canal preparation using single-file Ni-Ti systems. Exp Ther Med 15, 494-499.
Li SH, Lu Y, Song D, Zhou X, Zheng QH, Gao Y et al. (2015) Occurrence of Dentinal Microcracks in Severely Curved Root Canals with ProTaper Universal, WaveOne, and ProTaper Next File Systems. Journal of Endodontics 41, 1875-1879.
Liu R, Hou BX, Wesselink PR, Wu MK, Shemesh H (2013) The incidence of root microcracks caused by 3 different single-file systems versus the ProTaper system. Journal of Endodontics 39, 1054-1056.
Liu R, Kaiwar A, Shemesh H, Wesselink PR, Hou B, Wu MK (2013) Incidence of apical root cracks and apical dentinal detachments after canal preparation with hand and rotary files at different instrumentation lengths. Journal of Endodontics 39, 129-132.
Milani AS, Froughreyhani M, Rahimi S, Jafarabadi MA, Paksefat S (2012) The effect of root canal preparation on the development of dentin cracks. Iran Endod J 7, 177-182. Missau T, De Carlo Bello M, Michelon C, Mastella Lang P, Kalil Pereira G, Baldissara P et al.
(2017) Influence of Endodontic Treatment and Retreatment on the Fatigue Failure Load, Numbers of Cycles for Failure, and Survival Rates of Human Canine Teeth. J Endod 43, 2081-2087.
Moher D, Liberati A, Tetzlaff J, Altman DG, Group P (2009) Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. BMJ 339, b2535. Monga P, Bajaj N, Mahajan P, Garg S (2015) Comparison of incidence of dentinal defects after
root canal preparation with continuous rotation and reciprocating instrumentation. Singapore Dent J 36, 29-33.
Pedulla E, Genovesi F, Rapisarda S, La Rosa GR, Grande NM, Plotino G et al. (2017) Effects of 6 Single-File Systems on Dentinal Crack Formation. Journal of Endodontics 43, 456-461.
Pop I, Manoharan A, Zanini F, Tromba G, Patel S, Foschi F (2015) Synchrotron light-based µCT to analyse the presence of dentinal microcracks post-rotary and reciprocating NiTi instrumentation. Clinical Oral Investigations 19, 11-16.
Priya NT, Chandrasekhar V, Anita S, Tummala M, Raj TB, Badami V et al. (2014) "Dentinal microcracks after root canal preparation" a comparative evaluation with hand, rotary and reciprocating instrumentation. J Clin Diagn Res 8, Zc70-72.
Rose E, Svec T (2015) An Evaluation of Apical Cracks in Teeth Undergoing Orthograde Root Canal Instrumentation. Journal of Endodontics 41, 2021-2024.
Saha SG, Vijaywargiya N, Saxena D, Saha MK, Bharadwaj A, Dubey S (2017) Evaluation of the incidence of microcracks caused by Mtwo and ProTaper Next rotary file systems versus the self-adjusting file: A scanning electron microscopic study. J Conserv Dent 20, 355-359.
Sarkis-Onofre R, Skupien JA, Cenci MS, Moraes RR, Pereira-Cenci T (2014) The role of resin cement on bond strength of glass-fiber posts luted into root canals: a systematic review and meta-analysis of in vitro studies. Oper Dent 39, E31-44.
Shemesh H, Lindtner T, Portoles CA, Zaslansky P (2018) Dehydration Induces Cracking in Root Dentin Irrespective of Instrumentation: A Two-dimensional and Three-dimensional Study. J Endod 44, 120-125.
Shori DD, Shenoi PR, Baig AR, Kubde R, Makade C, Pandey S (2015) Stereomicroscopic evaluation of dentinal defects induced by new rotary system: "proTaper NEXT". Journal of Conservative Dentistry 18, 210-213.
Stringheta CP, Pelegrine RA, Kato AS, Freire LG, Iglecias EF, Gavini G et al. (2017) Micro– computed Tomography versus the Cross-sectioning Method to Evaluate Dentin Defects Induced by Different Mechanized Instrumentation Techniques. Journal of Endodontics 43, 2102-2107.
Swain MV, Xue J (2009) State of the art of Micro-CT applications in dental research. Int J Oral Sci 1, 177-188.
Thompson SA (2000) An overview of nickel-titanium alloys used in dentistry. Int Endod J 33, 297-310.
Topçuoğlu HS, Düzgün S, Akpek F, Topçuoğlu G (2016) Effect of glide path and apical preparation size on the incidence of apical crack during the canal preparation using Reciproc, WaveOne, and ProTaper Next systems in curved root canals: A stereomicroscope study. Scanning 38, 585-590.
Ustun Y, Aslan T, Sagsen B, Kesim B (2015) The effects of different nickel-titanium instruments on dentinal microcrack formations during root canal preparation. Eur J Dent 9, 41-46.
Walia HM, Brantley WA, Gerstein H (1988) An initial investigation of the bending and torsional properties of Nitinol root canal files. J Endod 14, 346-351.
Wei X, Hu B, Peng H, Tang M, Song J (2017) The incidence of dentinal cracks during root canal preparations with reciprocating single-file and rotary-file systems: A meta-analysis. Dent Mater J 36, 243-252.
Yoldas O, Yilmaz S, Atakan G, Kuden C, Kasan Z (2012) Dentinal microcrack formation during root canal preparations by different NiTi rotary instruments and the self-adjusting file. Journal of Endodontics 38, 232-235.
Zhou X, Jiang S, Wang X, Wang S, Zhu X, Zhang C (2015) Comparison of dentinal and apical crack formation caused by four different nickel-titanium rotary and reciprocating systems in large and small canals. Dent Mater J 34, 903-909.
Zuolo ML, De-Deus G, Belladonna FG, Silva EJ, Lopes RT, Souza EM et al. (2017) Micro-computed Tomography Assessment of Dentinal Micro-cracks after Root Canal Preparation with TRUShape and Self-adjusting File Systems. Journal of Endodontics 43, 619-622.
Figures captions and tables.
Figure 2: Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages
Table 1. Results of studies using non-destructive methodologies to evaluate microcracks Author Preparation technique System Results Presence of microcracks on baseline Instrumentation inducing, forming or propagating cracks Bayram et al., 2017 Rotary, Self-Adjusting File
ProTaper Universal (rot), ProTaper Gold (rot), Self-Adjusting File, XP-endo
Shaper (rot) Yes Cassimiro et al., 2017 Rotary, Reciprocating
ProTaper Next (rot), K3XF
(rot), WaveOne Gold (rec) Yes
Ceyhanli et al., 2016
Rotary, Reciprocating
ProTaper Universal (rot),
RaCe (rot), Safesider (rec) Yes The ProTaper Universal (Rot) system generated more post-instrumentation dentinal microcracks than the RaCe
system (Rot) de Oliveira et al., 2017 Manual, Rotary, Reciprocating
ProTaper Universal for Hand Use (manual), HyFlex CM
(rot), Reciproc (rec) Yes
De-Deus et a., 2015
Rotary, Adaptive
ProTaper Next (rot), Twisted
File Adaptive (TFA) Yes
De-Deus et a., 2017
Rotary, Reciprocating
Reciproc (rec), ProTaper Universal (rot) Yes (only in ProTaper Universal group) Li et al., 2018 Manual, Rotary, Reciprocating
WaveOne (rec), OneShape (rot), Reciproc (rec), K-file
(manual)
Yes
The OneShape system (Rot) resulted in increased
microcracks
Pop et al., 2015
Rotary, Reciprocating
ProTaper (rot), WaveOne
(rec) Yes Both systems induced microcracks
Stringheta et al., 2017
Rotary, Reciprocating
Reciproc (rec), ProTaper Next (rot), WaveOne Gold (rec), ProDesign Logic (rot)
Yes Zuolo et al., 2017 Rotary, Reciprocating, Self-Adjusting File
TRUShape (rot), Self-Adjusting File, BioRace (rot),
Reciproc (rec)
Yes
rot - rotatory; rec - reciprocating; TFA - twisted file adaptive; - No formation of new microcracks; + Formation of new microcracks
Table 2. Results of studies that used destructive methodologies to evaluate the microcracks.
Author Preparation technique System
Non-prepared teeth as baseline comparison Results Presence of microcracks on
baseline Instrumentation inducing, forming or propagating cracks Arias et al.,
2014
Hand, Reciprocating
Profile GT (hand), WaveOne
(rec) Yes Yes
No indicatives of formation of microcracks in comparison to non-instrumented teeth
Aydin et al., 2015
Reciprocating , TFA
Reciproc (rec), WaveOne (rec),
TFA (adaptive motion) Yes
No (Non instrumented teeth show absence of microcracks)
Formation of microcracks regardless of instrumentation system used. Ashwinkum ar et al., 2014 Hand, Rotary, Reciprocating
NiTi K-files (manual); ProTaper (manual); ProTaper (rot);
WaveOne (rec)
Yes
No (Non instrumented teeth show absence of microcracks)
ProTaper rotary files were associated with significantly more microcracks than ProTaper hand files and WaveOne Primary reciprocating files. Ni–Ti hand K-files did not produce microcracks at any
levels inside the root canals.
Bahrami et al., 2017
Hand, Rotary, Reciprocating
Stainless steel K-Flexo files (hand), TRUShape (rot),
WaveOne Gold (rec)
Yes Yes
No indicatives of formation of microcracks in comparison to non-instrumented teeth.
(There was no relationship between the shaping kinematics (hand preparation, WaveOne reciprocation, and rotary TRUShape) and the
frequency of microcracks)
Bier et al.,
2009 Hand, Rotary
Flexofiles (hand), ProTaper (rot), ProFile (rot), SystemGT
(rot), S-ApeX (rot)
Yes
No (Non instrumented teeth show absence of microcracks)
Hand instrumentation and rotary instrumentation with S-ApeX system show absence of microcracks.
However, the use of other rotary NiTi instruments resulted in formation of microcracks. Borges et al., 2018 Hand, Rotary, Reciprocating
Stainless steel K-files (hand), ProTaper Universal (rot), ProTaper Next (rot), ProFile (rot), Reciproc (rec), WaveOne
(rec)
Yes
No (Non instrumented teeth show absence of microcracks)
All instruments lead to the formation of microcracks, regardless of the enlargement or not of the cervical portion.
Burklein et al., 2013
Rotary, Reciprocating
Mtwo (rot), ProTaper (rot),
Reciproc (rec), WaveOne (rec) Yes No
Formation of microcracks regardless of instrumentation system used.
