Introduction: The aim of this in vitro study was to determine the influence of two glide path preparation methods on the fracture rate of the Primary 25/08 WaveOne reciprocating instrument. The number of simulator Endo-Training-Blocks in each group were calculated at the time of instrument fracture and compared to determine the influence of glide path preparation on the failure rate of the Primary 25/08 WaveOne reciprocating instrument. Preparation times for different glide path methods and total time for root canal preparation, with or without glide path, was also calculated. Materials and Methods: Simulator Endo-Training-Blocks (n = 300) were selected and randomly divided into 3 groups (n = 100). The 3 groups were then sub-divided into 5 smaller groups (n = 20). Root canal preparation was done with new primary 25/08 WaveOne instruments allocated to each group (5 in total for each group, 1 for each sub-group) following different methods for glide path preparation. Group 1: no glide path (control); Group 2: glide path preparation with stainless-steel hand files (size 10 K-File followed by size 15 K-File and finally size 20 K-File until loose fitting); and Group 3: glide path preparation with rotary PathFiles (size 10 K-File until loose fitting followed by PathFile no.1 (ISO 13 tip), PathFile no.2 (ISO 16 tip) and finally PathFile no. 3 (ISO 19 tip)). The Primary 25/08 WaveOne reciprocating instrument was used with the WaveOne endodontic motor in “WaveOne All “mode with a brushing motion on the outstroke. Simulated root canals were irrigated with sterile water and Glyde was used as lubricating agent. The outcome was measured by recording how many simulators could be prepared with one instrument before instrument breakage occurred. The preparation protocol was repeated 5 times. The time it took to prepare the glide path and the total preparation time was also calculated. The data of the different parts of the project were collected and statistically analysed using the ANOVA / Bonferroni test. Results: Glide path preparation with PathFiles was significantly faster (13.3 s ± 2.60 s) than with hand files (25.1 s ± 1.70 s) (P < 0.001). The highest number of simulators could be prepared after glide path preparation was performed with PathFiles (19.2 ± 0.84) (P < 0.001). Pairwise comparisons at the Bonferroni adjusted significance level of 0.017 demonstrated that there were statistical significant differences (P < 0.001) when PathFiles (19.2 ± 0.84) and hand files (17.6 ±1.14) were compared to the no glide path group (7.4 ± 0.89). There was no statistical significant difference between PathFiles and hand files groups. Total Preparation time was significantly shorter (P < 0.001) when an initial glide path was prepared with PathFiles (12.7 ± 0.22 s). The longest preparation time (P < 0.001) was calculated in group 1 where no glide path (21.2 ± 0.20 s) was present and the Endo-Training-Blocks were left undisturbed. Conclusion: Initial glide path preparation with PathFiles resulted in shorter preparation time (glide path and total preparation) and allowed a higher number of simulators prepared before failure of the WaveOne instrument. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Odontology / unrestricted

O controle da extrusão apical durante a reintervenção endodôntica é essencial para o sucesso do novo tratamento. Nesse contexto, o presente estudo teve como objetivo comparar a quantidade de material sólido extruído na desobturação de canais radiculares variando-se a técnica de esvaziamento e o limite de obturação. Foram utilizados 40 incisivos inferiores previamente tratados divididos em dois grupos de acordo com o limite de obturação estabelecido. Cada grupo foi subdividido em dois subgrupos levando-se em conta a técnica de desobturação empregada; manual (subgrupos A1 e B1) e mecânico-rotatória com limas de Ni-Ti (Quantec LX) (subgrupos A2 e B2). O material sólido extruído foi coletado por meio do sistema de filtração Millipore, levado à secagem em dessecador de sílica e pesado em balança analítica de precisão. Os resultados obtidos foram submetidos a ANOVA para dois fatores de variação sendo em seguida empregado o Teste de Tukey (&#945; = 5%). A técnica de desobturação mecânico-rotatória produziu menor extrusão (0,66mg) que a manual (1,11mg), havendo diferença estatística significante entre elas (p < 0,05). Os canais preenchidos até o vértice radiográfico apresentaram maior quantidade de extrusão (1,38mg) do que os obturados 1 mm aquém do forame (0,39mg), observando-se diferença estatística significante entre eles (p < 0,05). A menor quantidade extrusão foi observada no subgrupo A2 (0,20mg), em que foi empregada a técnica rotatória de desobturação em canais obturados 1mm aquém do forame apical, sendo constatada diferença estatisticamente significante deste subgrupo com os demais (p < 0,05). A extrusão de material sólido durante a desobturação de canais radiculares é influenciado pela técnica empregada e pelo limite apical de obturação. / The apical extrusion control during the endodontic retreatment is essential for the success of the new treatment. The purpose of this study was to compare the quantity of solid apically extruded material during filling removal according the gutta-percha removal technique and root filling limit. Forty mandibular incisors with a single straight canal were selected. The canals were previously endodontically treated and then divided into two groups according the filling level. Each group was subdivided in two groups considering the retreatment technique: stainless steel hand files (subgroups A1 and B1) versus niquel-titanium rotatory instruments (subgroups A2 and B2). The extruded solid material was collected by Millipore filtration system, dried in silica desiccators and weighed in an eletrobalance. The results were analyzed using ANOVA with two variation factors and Tukey Test (&#945; = 5%). The niquel-titanium rotatory instruments produced less extrusion (0,66mg) than the stainless steel hand files (1,11mg), with significant statistical difference between them (p < 0,05). The canals filled until the radiographic apex showed larger amount of extruded material (1,38mg) than those filled 1 mm beyond the foramen (0,39mg). It was observed significant statistical difference between them (p < 0,05). The smaller extruded debris amount was observed in subgroup A2 (0,20mg), in which one the rotary technique was used to remove the gutta-percha of canals filled 1mm beyond the apical foramen. It was verified significant statistical difference of this subgroup with the other ones (p < 0,05). The extrusion of solid material during the gutta-percha removal is influenced by the technique as well as the apical filling limit.

O controle da extrusão apical durante a reintervenção endodôntica é essencial para o sucesso do novo tratamento. Nesse contexto, o presente estudo teve como objetivo comparar a quantidade de material sólido extruído na desobturação de canais radiculares variando-se a técnica de esvaziamento e o limite de obturação. Foram utilizados 40 incisivos inferiores previamente tratados divididos em dois grupos de acordo com o limite de obturação estabelecido. Cada grupo foi subdividido em dois subgrupos levando-se em conta a técnica de desobturação empregada; manual (subgrupos A1 e B1) e mecânico-rotatória com limas de Ni-Ti (Quantec LX) (subgrupos A2 e B2). O material sólido extruído foi coletado por meio do sistema de filtração Millipore, levado à secagem em dessecador de sílica e pesado em balança analítica de precisão. Os resultados obtidos foram submetidos a ANOVA para dois fatores de variação sendo em seguida empregado o Teste de Tukey (&#945; = 5%). A técnica de desobturação mecânico-rotatória produziu menor extrusão (0,66mg) que a manual (1,11mg), havendo diferença estatística significante entre elas (p < 0,05). Os canais preenchidos até o vértice radiográfico apresentaram maior quantidade de extrusão (1,38mg) do que os obturados 1 mm aquém do forame (0,39mg), observando-se diferença estatística significante entre eles (p < 0,05). A menor quantidade extrusão foi observada no subgrupo A2 (0,20mg), em que foi empregada a técnica rotatória de desobturação em canais obturados 1mm aquém do forame apical, sendo constatada diferença estatisticamente significante deste subgrupo com os demais (p < 0,05). A extrusão de material sólido durante a desobturação de canais radiculares é influenciado pela técnica empregada e pelo limite apical de obturação. / The apical extrusion control during the endodontic retreatment is essential for the success of the new treatment. The purpose of this study was to compare the quantity of solid apically extruded material during filling removal according the gutta-percha removal technique and root filling limit. Forty mandibular incisors with a single straight canal were selected. The canals were previously endodontically treated and then divided into two groups according the filling level. Each group was subdivided in two groups considering the retreatment technique: stainless steel hand files (subgroups A1 and B1) versus niquel-titanium rotatory instruments (subgroups A2 and B2). The extruded solid material was collected by Millipore filtration system, dried in silica desiccators and weighed in an eletrobalance. The results were analyzed using ANOVA with two variation factors and Tukey Test (&#945; = 5%). The niquel-titanium rotatory instruments produced less extrusion (0,66mg) than the stainless steel hand files (1,11mg), with significant statistical difference between them (p < 0,05). The canals filled until the radiographic apex showed larger amount of extruded material (1,38mg) than those filled 1 mm beyond the foramen (0,39mg). It was observed significant statistical difference between them (p < 0,05). The smaller extruded debris amount was observed in subgroup A2 (0,20mg), in which one the rotary technique was used to remove the gutta-percha of canals filled 1mm beyond the apical foramen. It was verified significant statistical difference of this subgroup with the other ones (p < 0,05). The extrusion of solid material during the gutta-percha removal is influenced by the technique as well as the apical filling limit.