An In Vitro Model to Investigate Filling of Lateral Canals

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...

Filling of simulated lateral canals with gutta-percha or thermoplastic polymer by warm vertical compaction

“…10 Such small diameters, together with their location within the root canal system, may affect the filling of lateral canals. In this study, #8 and #10 K-files were used to create the simulated lateral canals.…”

“…In this study, #8 and #10 K-files were used to create the simulated lateral canals. Venturi et al 10 and Venturi 23 observed that natural apical ramifications were often left incompletely filled after warm vertical compaction. However, the technique used in this study proved safer, by promoting less extrusion of filling material than the Termafil technique.…”

“…The working length (WL) was established by subtracting 1mm from the entire length. After the root canals were prepared, the teeth were subjected to a tooth decalcification and clearing procedure using a technique described by Venturi et al 10,18 First, the specimens were decalcified in a solution of 5% hydrochloric acid (Hexis Científica S/A, Jundiaí, Brazil), which was changed every 24 hours for approximately 5 days, until the teeth became rubber-like in texture. Afterwards, #8 and #10 K-files were inserted through the labial and lingual root surfaces at 2, 5, and 8 mm from the WL up to the main root canal, creating the simulated lateral canals.…”

“…9 Warm compaction of filling materials using the Touch'n Heat system has demonstrated its ability to seal simulated lateral canals. 9,10 Resilon was proposed in 2004 as a solid core root canal filling material (Resilon Research, LLC, North Branford, USA). This material is a thermoplastic synthetic polymer containing bioactive glass, bismuth oxychloride, and barium sulfate.…”

“…Simulated lateral canals can be made in artificial 14,15 or natural teeth. 16,17 Root canal fillings may be evaluated using radiographic examination, 16 tooth decalcification and clearing methods, 10 or by an association of methods. 17 The effectiveness of the warm vertical compaction technique depends on the thermal plasticization property of the material to be used.…”