Orlando Limongi

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 Tukeys 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.

Flexibility of K3 and ProTaper universal instruments

This study used a mechanical test to evaluate the flexibility of instruments from the K3 (conicity 0.04) and the ProTaper Universal systems when they were new and after 5 uses in simulated canals. Five sets of instruments of each system were tested: K3 (15, 20, 25, 30, 35, 40 and 45) and ProTaper Universal (S1, S2, F1, F2, F3, F4 and F5). Each set of instruments was used to prepare a simulated canal and the same set of instruments was used 5 times (50 canals). The number of each subgroup represented the number of uses: 0 (control), 1, 3 and 5 uses. Before and after each use, the instruments were submitted to a mechanical flexibility test performed in a Versat 502 universal testing machine. Interactions between the instrument and the number of uses were analyzed by ANOVA and Tukeys test at a 5% level of significance. Instruments from both systems presented lower flexibility after the third use compared to the flexibility obtained after uses 0 and 1 (p<0.05), and maintained the same flexibility after the fifth use. The flexibility of instruments from the K3 system decreased with the increase of diameter, irrespective of the number of uses. Among the instruments from the ProTaper Universal system, the shaping files presented greater flexibility than the finishing files. F2 and F3 were the least flexible instruments, and F4 and F5 presented flexibility values similar to those of F1.

Wear promoted in the apical third of simulated canals after instrumentation with protaper universal system

Objective: This study evaluated the wear in the apical third of simulate canals after preparation with ProTaper Universal Rotary System. Material and Methods: 24 sets of instruments were used in 24 simulated canals in transparent epoxy resin blocks with degree of curvature of either 20°or 40°. The canals were photographed preoperatively and after preparation of the apical stop with ProTaper F3, F4 and F5 instruments. The initial and final images were exported to Adobe Photoshop® software and superimposed to detect the root canal wall differences (in mm) between them, in two points located 1 (A) and 5 (B) mm from the point where the working length was established. Data were subjected to analysis of variance to verify the existence of interaction among the factors: canal curvature, instrument size and curve location. Significant level was set at 5%. Results: Regardless of the location and the canal curvature, F4 and F5 instruments produced the greatest wear (p<0.05). Conclusions: There was a deviation from the original pathway towards the outside of the root curvature in both analyzed points. All instruments produced canal transportation, but the F4 and F5 instruments produced more than the other instruments, and should thus be used with care in curved canals.

Análise do desgaste produzido no preparo de canais radiculares com o sistema oscilatório em três diferentes velocidades

Introducao: Este estudo avalia, in vitro, a quantidade de desgaste produzido por instrumentos endodonticosde aco inoxidavel, acionados a um sistema automatizado de movimento oscilatorio, em tres diferentesvelocidades: 6.000, 8.000 e 10.000 rotacoes por minuto. Metodos: Para isso, foram utilizadas 18 raizespalatinas de molares superiores, que foram distribuidas aleatoriamente em tres grupos experimentais eindividualmente pesadas em uma balanca digital analitica, antes e depois do preparo endodontico. Resultadoe Conclusao: A comparacao entre as medias de pesagem obtidas em cada grupo possibilitou concluirque nao houve diferenca estatistica significativa quanto a quantidade de desgaste produzido entre as tresvelocidades testadas Introduction: This study evaluates, in vitro, the amount of produced consuming for stainless steel endodonticinstruments, defendant in an automatized system of oscillatory movement, in three different speeds:6.000, 8.000 and 10.000 rotations per minute. Methods: For this, 18 palatines root canals of superior molarsuperiors had been used, that had been randomly distributed in three individually weights in experimentalgroups and in an analytical digital scale before and after the endodontic preparation. Result and Conclusion:The comparison between the averages of weight in each group made possible to conclude that there were nosignificant statistical difference to the amount of consuming produced among of the three tested speeds