Reciprocating kinematics leads to lower incidences of postoperative pain than rotary kinematics after endodontic treatment: A systematic review and meta-analysis of randomized controlled trial.

BACKGROUND: Extrusion of infected debris into the periapical tissue has been cited as the major cause of postoperative pain, regardless of instrumentation technique. AIM: Comprehensively review two different kinematics of instrumentation (reciprocating and rotary) and association to the postoperative pain after endodontic treatment. METHODS: Two investigators performed a systematic review with meta-analysis. MEDLINE/PubMed, Cochrane Library, and Scopus supplied relevant data from studies published until February 2018 to answer the PICO question. Primary outcome was overall postoperative pain, and the secondary outcomes were nature of the pain (mild, moderate, and severe) at 12, 24, and 48 h. RESULTS: Ten randomized clinical trials fulfilled eligibility criteria, and five of them were submitted in the meta-analysis. Primary outcome indicated that reciprocating system results in less postoperative pain compared to rotary system (P < 0.05). As a secondary outcome, there was no statistical difference for mild, moderate, and severe pain after 12 and 24 h using reciprocating or rotary systems (P > 0.05). However, the reciprocation system showed less severe pain after 48 h (P < 0.05). CONCLUSION: Rotary motion had a negative impact on postoperative pain after endodontic treatment. Furthermore, after 48 h, more patients presented severe pain under rotary motion. More randomized clinical studies would be helpful.

Cyclic Fatigue Resistance of Heat-Treated Nickel-Titanium Instruments.

INTRODUCTION: This study compared the cyclic fatigue resistance (CFR) of new instruments manufactured by heat-treated nickel-titanium wire. METHODS AND MATERIALS: Ninety-six new instruments from HyFlex CM (HF), Edge File (EF), Pro Design S (PDS/L) and Mtwo (MT) (20/0.06 and 25/0.06) (n=12) systems were evaluated. A stainless steel device was used and time and number of cycles to fracture (NCF) were observed. Fragments were measured and fracture surface was evaluated using scanning electron microscope (SEM). ANOVA and Tukey's tests were applied with the level of significance set at 0.05. RESULTS: PDS 20/0.06 and PDL 25/0.06 instruments presented the highest CFR. MT 20/0.06 and MT 25/0.06 showed the lowest CFR (P<0.05). The length of fragments was similar for 25/0.06 instruments and HF presented the highest one for 20/0.06 instruments. SEM analyses showed morphology suggestive of ductile fracture. CONCLUSION: Heat treatment increased resistance to cyclic fatigue differently for each type of instrument. PDS 20/0.06 and PDL 25/0.06 present higher cyclic fatigue resistance.

Mechanical Preparation Showed Superior Shaping Ability than Manual Technique in Primary Molars - A Micro-Computed Tomography Study

Abstract The aim of the study was to evaluate canal preparation in primary molars with hand files, ProTaper Next and Self-Adjusting File (SAF) by 2D and 3D micro-computed tomography (micro-CT) analysis. Canals of 24 primary molars were prepared with hand files (HF), ProTaper Next (PTN) and SAF (n=8/group). The teeth were scanned before and after root canal preparation and the pre- and postoperative micro-CT images were reconstructed. Changes in 2D (area, perimeter, roundness, minor and major diameter) and 3D [volume, surface area, structure model index (SMI)] morphological parameters, as well as canal transportation and lateral perforations were evaluated (Kruskal-Wallis and ANOVA; a=0.05). SAF presented smaller changes in minor diameter, volume and surface area compared with HF and PTN (p<0.05). PTN presented more circular canals after preparation. 3D analysis revealed greater transportation in HF. PTN and SAF presented more centered canal preparation, especially in curved areas. SAF and HF presented, respectively, the lowest (0.05±0.02 and 0.07±0.04) and highest (0.14±0.11 and 0.29±0.17) apical transportation. There were fewer lateral perforations in SAF (4.2%) and PTN (7.7%) than in HF (47.8%) (p<0.05). In primary molars, mechanical preparation showed better shaping ability than hand files, promoting more centered preparations and lower occurrence of lateral perforations and canal transportation. Clinical Relevance: Manual instrumentation is still reported as the main choice in the primary teeth preparation; however, studies have shown limitations in its use. The morphological characteristics of primary teeth and the limited knowledge of shaping procedures in these teeth using mechanical preparation become a challenge for clinical practice and might impair the predictability of endodontic treatment.

Resumo Este estudo avaliou o preparo do canal radicular em molares decíduos com sistema manual e mecanizado [ProTaper Next e Self-Adjusting File (SAF)], por meio de parâmetros morfológicos bi (2D) e tridimensionais (3D) em microtomografia computadorizada (micro-CT). Canais radiculares de 24 molares decíduos foram preparados com limas manuais (M), ProTaper Next (PTN) e SAF (n=8/grupo). Os dentes foram escaneados antes e após o preparo do canal radicular e as imagens de micro-CT pré e pós-operatória foram reconstruídas. As mudanças nos parâmetros morfológicos 2D (área, perímetro, circularidade, menor e maior diâmetro) e 3D [volume, área de superfície, índice de estrutura do modelo (SMI)], bem como o transporte do canal radicular e a presença de perfurações laterais foram avaliadas (Kruskal-Wallis and ANOVA; a=0.05). SAF apresentou menores mudanças no diâmetro menor, volume e área de superfície quando comparado com M e PTN (p<0.05). PTN mostrou canais mais circulares após o preparo. A análise 3D revelou maior transporte para o grupo M. PTN e SAF mostraram maior centralização do preparo do canal radicular, especialmente em áreas de curvatura. SAF e M apresentaram, respectivamente, o menor (0,05±0,02 e 0,07±0,04) e o maior (0,14±0,11 e 0,29±0,17) transporte apical. Foi possível observar menor porcentagem de perfurações laterais para os grupos SAF (4,2%) e PTN (7,7%) comparados ao grupo M (47,8%) (p<0.05). Conclui-se que o preparo mecanizado dos canais radiculares em molares decíduos, apresentou melhor capacidade de modelagem do que as limas manuais, promovendo preparos mais centralizados e menor ocorrência de perfurações laterais e transporte do canal.

Negotiability of Second Mesiobuccal Canals in Maxillary Molars Using a Reciprocating System.

The aim of this prospective case series report was to assess the frequency in which the Reciproc R25 instrument (VDW, Munich, Germany) is able to scout and reach the full working length (WL) in second mesiobuccal (MB2) canals from maxillary molars. Conventional hand file negotiation was used as the reference technique for comparison. Maxillary molars (270 first molars and 71 second molars) were included in this study. After local anesthesia, the tooth was isolated with a rubber dam, and traditional straight-line access was made. After locating both first mesiobuccal and MB2 canals, patients were randomly assigned to one of the experimental groups (conventional hand filing preparation or R25 Reciproc preparation). All cases in which the hand files (G1) and R25 instrument (G2) were able to reach the fully electronically determined WL were classified as "reaching full WL" (RFWL). All cases in which the hand files (G1) and R25 instrument (G2) were unable to negotiate the full-length canal were classified as "not reaching full WL" (NRFWL). The number of root canals classified as RFWL and NRFWL from both groups were recorded and tabulated on an Excel data sheet (Microsoft, Redmond, WA). The frequency distributions (%) of root canals classified as RFWL and NRFWL were compared with overall-treated canals and for each treatment approach (hand file and R25 instrument) using a Pearson chi-square test. In group 1, the hand file approach reached the full WL in 57.48% of cases, whereas in group 2 the R25 instrument reached the full WL in 85.63% of cases. Three file separations occurred in each group while negotiating the MB2 canal. According to this study, the R25 instrument was 32% more effective when compared with hand files in scouting and negotiating MB2 canals in maxillary first and second molars. There was no difference with regard to file separation when comparing both preparation techniques.

Apical extrusion of debris in flat-oval root canals after using different instrumentation systems.

INTRODUCTION: The purpose of this study was to evaluate the amount of apically extruded debris in flat-oval root canal systems during cleaning and shaping with different instrumentation systems. METHODS: Seventy-two mandibular incisors were randomly assigned to 4 groups (n = 18) according to the instrumentation system to be used: the ProTaper Next rotary system (PTN; Dentsply Tulsa Dental, Tulsa, OK), the WaveOne reciprocating system (WO, Dentsply Tulsa Dental), the Twisted File Adaptive (TFA; SybronEndo, Orange, CA) rotary/reciprocating system, and the Self-Adjusting File (SAF) system (ReDent-Nova, Ra'anana, Israel). Debris extruded during the instrumentation was collected and dried in preweighed Eppendorf tubes. Three consecutive weights were obtained for each tube, and the average was calculated. The data were analyzed using the t test and analysis of variance (Games-Howell test). RESULTS: The SAF produced significantly more debris compared with the other systems (P < .05). No significant difference was noted amongst the PTN, WO, and TFA (P > .05). CONCLUSIONS: Regardless of the instrumentation system used, apical extrusion of debris was exhibited at some level, regardless of the instrumentation system used. The SAF was associated with the highest amount of debris extrusion compared with PTN, WO, and TFA.

In vitro comparative study of manual and mechanical rotary instrumentation of root canals using computed tomography

This in vitro study compared, using computed tomography (CT), the amount of dentin removed from root canal walls by manual and mechanical rotary instrumentation techniques. Forty mandibular incisors with dental crown and a single canal were selected. The teeth were randomly assigned to two groups, according to the technique used for root canal preparation: Group I - manual instrumentation with stainless steel files; Group II - mechanical instrumentation with RaCe rotary nickel-titanium instruments. In each tooth, root dentin thickness of the buccal, lingual, mesial and distal surfaces in the apical, middle and cervical thirds of the canal was measured (in mm) using a multislice CT scanner (Siemens Emotion, Duo). Data were stored in the SPSS v. 11.5 and SigmaPlot 2001 v. 7.101 softwares. After crown opening, working length was determined, root canals were instrumented and new CT scans were taken for assessment of root dentin thickness. Pre- and post-instrumentation data were compared and analyzed statistically by ANOVA and Tukey's post-hoc test for significant differences (p=0.05). Based on the findings of this study, it may be concluded that regarding dentin removal from root canal walls during instrumentation, neither of the techniques can be considered more effective than the other.

Este estudo in vitro avaliou comparativamente, por meio de tomografia computadorizada (TC), a quantidade de dentina removida das paredes do canal radicular utilizando-se as técnicas de preparo manual e automatizada de instrumentação rotatória. Foram selecionados 40 incisivos inferiores com coroa dental e um único canal. Os dentes foram divididos aleatoriamente em 2 grupos, de acordo com a técnica empregada para o preparo dos canais radiculares: Grupo I - técnica manual com limas manuais de aço inoxidável e Grupo II - técnica automatizada de movimentos rotatórios RaCe com limas de níquel-titânio. Em cada dente, procedeu-se à mensuração (em mm) da espessura da dentina radicular nas faces vestibular, lingual, mesial e distal dos terços apical, médio e cervical por meio de tomografia computadorizada multislice (Siemens Emotion, Duo). Os dados coletados foram armazenados utilizando-se os softwares SPSS versão 11.5 e SigmaPlot 2001 v. 7.101 (SPSS Inc.). Após a abertura coronária, o comprimento de trabalho foi estabelecido, os canais radiculares foram instrumentados e novas tomadas de tomografia computadorizada foram realizadas para mensuração da espessura das paredes dentinárias radiculares. Os dados obtidos antes e após o preparo biomecânico dos canais foram comparados. Os resultados foram estatisticamente por meio de análise de variância (ANOVA) com localização de diferenças post hoc de Tukey (p=0,05). Com base nos achados desse estudo, pode-se concluir que: com relação à remoção de dentina das paredes dos canais radiculares durante a instrumentação nenhuma das técnicas avaliadas pode ser apontada como mais efetiva que a outra.