A comparative study on the effect of three methods of instrumentation on the shape of root canal (an in-vitro study).

This study compared the ability of three types of engine driven instrumentation techniques to negotiate and prepare small, slightly curved root canals. Forty five mesial roots of extracted maxillary and mandibular first permanent molars were classified into three groups. Group (I) was prepared by Canal Leader system, group (II) was prepared by Nickel Titanium files and group (III) was prepared by Canal Master technique. Radiographs of the root canal space before and after preparation was carried out by the aid of an experimental model. Enlarged photographic prints obtained from radiographs were scored for shaping effectiveness of the three techniques in respect to canal course, position & width of apical constriction and lack of ledge formation. The results indicated that the Canal Leader system was an efficient technique in maintaining canal curvature, absence of zipping, transportation or ledge formation in almost all of the specimen tested, followed by the Nickel Titanium files and then the Canal Master technique which produced more straightening and destruction of apical constriction.

Effectiveness of two rotary instrumentation techniques for cleaning the root canal.

An in vitro study was undertaken to compare the efficiency of two rotary endodontic devices for cleaning the root canal wall(s). Only mesial roots of mandibular first molar were used. Forty roots were classified into two equal groups. Group (I) was instrumented using the Canal Finder system, Group (II) was instrumented using Nickel Titanium files. In both groups half of the specimens received a final flush of 17% EDTA and 5.25% NaOCl solutions. Roots were sectioned longitudinally and Scanning Electron Micrographs were taken at three levels (Coronal, Middle and Apical) of each section of the prepared roots. Statistical analysis of the results showed that the Canal Finder system produced a clean canal surface when 17% EDTA and 5.25% NaOCL were used as an irrigating solutions, while Nickel Titanium files had a superior cleaning efficiency than the Canal Finder with either irrigating solution.

Dentin wall adaptation of multiphase versus temperature thermoplasticized gutta-percha. A scanning electron microscopic study.

An in-vitro study was designed to compare dentin wall adaptation of Multiphase gutta-percha root canal obturation technique versus high temperature thermoplasticized gutta-percha (Obtura) in the presence and absence of smear layer. Forty single rooted teeth with straight canals were used. After decapitation roots were divided into two equal groups. Group (I) received final irrigation with EDTA and Sodium hypochlorite (NaOCI) to remove the smear layer, while roots in Group (II) were irrigated with NaOCI alone. Each group was then subdivided into two subgroups to represent the two filling techniques. Teeth were sectioned longitudinally and viewed under scanning electron microscope. Multiphase gutta-percha showed excellent adaptation to canal wall, specially in the absence of smear layer and displayed a homogeneous mass with little amount of voids than the Obtura system.

Comparative sealability study on root canal obturation using multiphase gutta percha and lateral condensation technique.

An in-vitro dye leakage study was performed to compare the apical microleakage of recently introduced multiphase obturation system to lateral condensation technique using methylene blue dye. Thirty single rooted human teeth were divided randomly into two equal groups. Group A were filled with multiphase technique using Tubliseal sealer and group B were filled with lateral condensation technique using the same sealer (control). Root canal preparation of both groups were carried out with nickel titanium files. Statistical analysis revealed that multiphase technique exhibited lower mean leakage (0.6) than lateral condensation technique (1.72). In addition some specimen filled with multiphase technique showed zero degree leakage.

The antibacterial effect of SPAD.

The antibacterial effect of SPAD, a root canal obturation paste containing paraformaldehyde, was examined and compared with that of calcium hydroxide apexification paste (Pulpdent). Both materials were either immediately placed in cultures containing streptococci group D, isolated from infected root canals, stored in an incubator for 3, 7 and 15 days before their testing, Evaluation of the antibacterial effect was carried out by measuring the diameter of bacterial inhibition zone after incubation of the materials in cultures, for 24, 48 and 27 hours. Wide inhibition zones formed around SPAD, denoting it's strong antibacterial effect, were recorded. This effect decreased with time as a result of the decrease in the amount of formaldehyde released from the hardened material into culture. On the contrary, calcium hydroxide was unable to cause inhibition of bacterial growth throughout the period of the study.