Experimental study on central location ability and clearance rate of three nickel-titanium instruments for root canal retreatment / 口腔疾病防治

Objective@# Comparision of the central location ability and clearance rate of ProTaper retreatment, Fengdu O-file and M3-RT three kinds of nickel-titanium instruments and hand stainless instruments K-file, H-file. Observe the form of the root canal wall. To provide experimental basis and reference for the clinical application of nickel-titanium instruments for root canal retreatment.@*Methods @#40 simulated resin blocks with the same specification were randomly divided into four groups (n=10). Each group was separately prepared with hand stainless instruments K-file and H-file (group A1), ProTaper retreatment (group B1), Fengdu O-file (group C1), and M3-RT (group D1). Using scanner to obtain the pre- and post-operative images and overlapping the images through Photoshop. Measuring the root canal inner and outer wall resin removal with Image J, compared the central location ability of the four group. A total of 60 mandibular single canal premolars extracted due to orthodontics were collected. The teeth were randomly divided into four groups (n=15) after filling the root canal. Use hand stainless instruments K-file,H-file(group A2), ProTaper retreatment (group B2), Fengdu O-file(group C2) , M3-RT(group D2) to remove the filling materials. The roots were longitudinally sectioned, and the image of the root surface was photographed under the 10 × magnification microscope. The software was used to trace the area of the root canal wall and residual root filling, and the root filling clearance rate of each group was calculated. Two teeth were randomly selected in each group and observed under scanning electron microscope.@*Results@#Within 9 mm from the root tip hole, the central location ability of group B1, C1, D1 was better than that of group A1(P ＜ 0.05). At 4 mm from the root tip hole, group D1 has the best central location ability(P ＜ 0.05). There was no difference of the four instruments at a distance of 10 mm from the root tip hole（P ＞ 0.05）. There were various degree of filling material remained in the root canal after the four groups of instruments for retreatment canal preparation. There was no significant difference between group B2, C2, D2（P ＞ 0.05）, and both were higher than group A2(P ＜ 0.05). Scanning electron microscope observation results shown that the root canal wall prepared by group B2, C2, D2 was more smooth and continuous than group A2, and the residual filling material was less. @*Conclusion @#The central location ability of three kinds of nickel-titanium root canal retreatment instruments were significantly better than that of hand stainless instruments. ProTaper retreatment, Fengdu O-file and M3-RT three kinds of nickel-titanium root canal retreatment instruments showed good performance, the central location ability of M3-RT was slightly better. Nickel-titanium root canal retreatment instruments are more efficient than traditional hand stainless instruments in removing root fillings and the root canal wall after preparation is smoother and has good continuity.

Obturation Over an S1 ProTaper Instrument Fragment in a Mandibular Molar with Three Years of Follow-up

This case report describes root canal filling performed over a large S1 ProTaper file fragment in a second mandibular molar with irreversible pulpitis. An S1 ProTaper file was fractured during the instrumentation of the mesiobuccal canal. Approximately 10 mm of file fragment remained in the apical and middle thirds of the canal. The obturation was performed over this fragment using thermomechanically compacted gutta-percha and sealer. Radiographic findings and the absence of clinical signs and symptoms at 3-year follow up indicated successful treatment. Cone-beam computed tomography images revealed absence of periapical lesion and details of intracanal file fragment related to root fillings and apex morphology. In this case, the presence of a large intracanal fractured instrument did not have a negative impact on the endodontic prognosis during the follow up evaluation period.

Este relato de caso descreve a obturação do canal radicular realizada sobre um grande fragmento da lima ProTaper S1 em um segundo molar inferior com pulpite irreversível. Uma lima ProTaper S1 fraturou durante a instrumentação do canal mésio-vestibular. Aproximadamente 10 mm de remanescente do fragmento da lima permaneceu nos terços apical e médio do canal. A obturação foi realizada sobre este fragmento usando guta-percha compactada termomecanicamente e cimento endodôntico. Achados radiográficos e ausência de sinais e sintomas clínicos após 3 anos de acompanhamento indicaram o sucesso do tratamento. Imagens de tomografia computadorizada de feixes cônicos revelaram a ausência de lesão periapical e detalhes do fragmento da lima intracanal relacionados à obturação do canal radicular e à morfologia do ápice. Neste caso, a presença de grande instrumento fraturado intracanal não teve impacto negativo no prognóstico endodôntico durante o período de acompanhamento.

Comparison of the centering ability of Wave.One and Reciproc nickel-titanium instruments in simulated curved canals

OBJECTIVES: The aim of this study was to evaluate the shaping ability of newly marketed single-file instruments, Wave.One (Dentsply-Maillefer) and Reciproc (VDW GmbH), in terms of maintaining the original root canal configuration and curvature, with or without a glide-path. MATERIALS AND METHODS: According to the instruments used, the blocks were divided into 4 groups (n = 10): Group 1, no glide-path / Wave.One; Group 2, no glide-path / Reciproc; Group 3, #15 K-file / Wave.One; Group 4, #15 K-file / Reciproc. Pre- and post-instrumented images were scanned and the canal deviation was assessed. The cyclic fatigue stress was loaded to examine the cross-sectional shape of the fractured surface. The broken fragments were evaluated under the scanning electron microscope (SEM) for topographic features of the cross-section. Statistically analysis of the data was performed using one-way analysis of variance followed by Tukey's test (alpha = 0.05). RESULTS: The ability of instruments to remain centered in prepared canals at 1 and 2 mm levels was significantly lower in Group 1 (p < 0.05). The centering ratio at 3, 5, and 7 mm level were not significantly different. CONCLUSIONS: The Wave.One file should be used following establishment of a glide-path larger than #15.

Influência de instrumentos de níquel-titânio na qualidade tridimensional da modelagem radicular em molares superiores e inferiores / Influence of nickel-titanium instruments on tridimentional quality of root canal preparation in maxillary mandibular molars

Estudou-se a morfologia interna radicular de molares superiores e inferiores posterior a modelagem cominstrumentos de níquel-titânio em rotação contínua. Oitenta molares superiores e inferiores de humanosforam aleatoriamente distribuídos em quatro grupos, de acordo com os elementos dentais e os diferentes tipos de instrumentos: K , ProTaper, ProFile e K-FlexoFile. Posterior à instrumentação dos canais radiculares valendo-se de uma técnica de preparo com avanço progressivo cérvico-apical, realizou-se a moldagem com Aquasil ULV. A seguir, os dentes foram submetidos à desmineralização em ácido clorídrico a 35%, obtendo-se assim o molde correspondente à cavidade preparada. Estes foram analisados quanto à qualidade da morfologia interna por três examinadores. Os resultados foram tabulados e submetidos à análise estatística. Nos molares superiores pode-se observar 94,3% de formas regulares cônicas afuniladas, enquanto que, nos molares inferiores superfícies regulares cônicas foram verificadas em 86,95% das amostras analisadas. De um modo geral, os instrumentos de níquel-titânio influenciaram positivamente na qualidade da forma regular cônica afunilada cérvico-apical, com destaque para os instrumentos K e Protaper

The aim of the present study was to analyze the quality of the internal morphology of the root canals of maxillary molars, subsequent to the cleaning and shaping with nickel-titanium instruments with continuous rotation. Forty maxillary molar human teeth, were distributed on the basis of different types of endodontic instruments: K , ProTaper, ProFile e K-FlexoFile (control). The molding of the prepared root canals was carried out with Aquasil ULV impression material. The teeth were submitted to demineralization with chloridric acid at 35%. For the verification of the quality of the internal morphology three examiners analyzed the moldings. The technique used with ProTaper instruments showed a preparation with greater regularity index, considering the three thirds of the root canal. In maxillary molars it was observed 94,30% of regular conic form; in mandibular molar were verified surface with conic regular form in 86,95% of samples. K and Protaper showed a preparation with greater regularity index