No abstract

Aims of this work were to examine lateral canals in extracted teeth, to propose a new technique to produce artificial lateral canals, and to compare two obturation techniques. Cleared roots were examined to record measure and shape of lateral canals. Artificial lateral canals were prepared on human demineralized teeth before final clearing. Specimens were divided in two groups: canals of group 1 were filled with Schilder's technique, canals of group 2 were filled with vertical compaction with apical backfilling. Stereomicroscopic analysis of lateral canal filling revealed lower filling rates in apical canals compared to coronal ones and higher filling rates with "vertical compaction with apical backfilling" compared to Schilder's group. The tested procedure appears to be a reliable technique to obtain standardized lateral canals and to compare filling procedures. (5), other studies demonstrated a their potential pathogenicity after healing of periradicular lesions in relation with full filling of lateral canals (6 -8). Key WordsThe capability of an endodontic filling technique to ensure obturation and sealing of thin and irregular ramifications is an important clinical parameter, and may represent a favorable aspect of the filling technique. Among different techniques proposed over the years, the Schilder's technique has been shown to effectively fill lateral canals (9). Brothman (10) demonstrated that vertical compaction of warm gutta-percha approximately doubled number of filled lateral canals if compared to gutta-percha lateral compaction. Recently, the capability of filling lateral canals of a new obturation technique (11, 12) has also been investigated.Several in vitro models have been proposed to compare results of different filling techniques. For this purpose artificial lateral canals were created using various methods and resulting in different shape and size. Wong et al. (13) and Tagger and Gold (14) used a split and hinged hard metal model containing a main canal with extensions mimicking lateral canals, while other authors proposed resin blocks with a main curved canal with lateral ramifications (15-17). Tooth embedded in acrylic block was also proposed (18 -21): the resin block containing the tooth was longitudinally sectioned and root canal irregularities were subsequently produced with a one-half round bur, before re-approximate and secure the two halves. Goldberg et al. (22) created simulated lateral ramifications with reverse taper in human teeth by using a #15 engine reamer to drill into the center of the canal. Similarly Dulac et al. (16) used a #20 K file to fabricate lateral canals in epoxy resin blocks in which simulated root curved canals had been previously mechanically prepared. All these models of lateral canals have diameters greater than natural ones. In fact previous studies showed that 61.3% lateral branches in mandibular incisors and 70.1% in maxillary central incisors had thickness less than #10 reamer (23,24).Considering the high number of in vitro techniques proposed ov...

The modified tooth-clearing technique allowed observation of fine morphological details in all specimens. Effective gutta-percha filling was evident in most of the wide coronal lateral canals whilst the apical narrow ramifications were often incompletely filled by cement. Overall AH-Plus demonstrated better diffusion into lateral accessory canals compared to Pulp Canal Sealer.

Under the five different clinical situations both EALs revealed accurate measurements. Apex Finder was negatively influenced by NaOCl in the root canal. The Root ZX was more frequently unable to reveal stable measurements in low conductivity canals.

The use of the System-B Heat Source on root canals maintained at a constant body temperature by a thermostatic bath revealed that the increase of temperature of the gutta-percha at the apical third of the canal was negligible and that the compaction of the mass of the gutta-percha close to the apex was performed at body temperature. Minor changes in temperature of the outer surface of the root canals occurred, suggesting no danger for the periradicular tissues.