The DownPak device: Obturation with heat and vibration

Successful endodontic treatment depends on a proper diagnosis, a favorable prognosis assessment and proper cleaning, disinfection, shaping and obturation of the canals and their associated radicular spaces. Since countless studies have demonstrated that it may not be possible to thoroughly disinfect and clean all canal ramifications, obturation makes it possible to seal the roots internally to prevent leakage coronally or from periradicular tissues.¹ Presently, there is no ideal obturation material. Gutta-percha remains the primary obturation material in use today, although other obturation filling materials have gained some recent attention, including Resilon (Pentron Clinical Technologies) and ProRoot MTA (Dentsply Tulsa Dental). All of these materials have some limitation in their ability to three-dimensionally seal the main and accessory canals.

Nevertheless, it is important to obtain a homogenous mass of obturation material that will conform well to the interior walls of the canals when plasticized. Gutta-percha and Resilon are the most suitable materials. Heated gutta-percha changes its crystalline form from a beta phase, which is relatively solid, to an alpha phase, where it becomes a more plasticized and sticky material that adheres better to the canal walls.² In its alpha phase, gutta-percha can be compacted vertically and laterally, either by mechanical or rotary instruments. Resilon, a polyester- and methacrylate-based resin obturation material, has good flow when warmed. One study concludes that Resilon bonds to etched canal walls when heated, which may provide a tighter seal of the canal system while also strengthening the root system.³

Several techniques have been used to facilitate the placement of gutta-percha, including cold and warm lateral compaction, warm vertical compaction, injectable systems, carrier-based obturation and thermomechanical compaction. All of these techniques require various degrees of clinical proficiency, and, depending on the canal system that is to be obturated, certain techniques may be more appropriate than others. For example, when a tooth has a large internal resorption defect in the canal, cold lateral compaction may not adequately fill all of the canal space, whereas vertically compacting or injecting warm gutta-percha may provide a more three-dimensional obturation. Considering the multitude of canal ramifications in any given tooth, it may be impossible to fill these spaces three-dimensionally unless the gutta-percha is heated. In vitro studies have demonstrated that cold lateral compaction of gutta-percha is approximately 25 per cent less dense than warm lateral compaction; additionally, it has been shown that gutta-percha fills significantly more canal space when warm vertical compaction is used.^4-6 Even after heating and compacting gutta-percha or Resilon into a canal system, there still may be voids in the obturation. To minimize this problem, Martin developed a self-contained electronically heated spreader for warming and laterally compacting gutta-percha (Endotec, Medidenta International). This device significantly enhanced the compaction of gutta-percha.⁷

A 1993 study found that the Endotec device increased the density of the obturation by approximately 15 percent.⁸ Although this obturation device is no longer commercially available, it demonstrated that electrically induced heat on a spreader or plugger tip was an efficient way of delivering heat to gutta-percha, producing a denser obturation as a result. Subsequently designed obturation heating systems, the Touch ’n Heat (Sybron-Endo) and the System B (SybronEndo), expanded on this concept and were found to be successful for creating a more homogenous obturation of gutta-percha.⁹ The EndoTwinn (MDCL) is another such device that has been used throughout Europe for many years. Like the Endotec, the EndoTwinn is a hand-held, self-contained, heat-carrying instrument with spreader or plugger tips. Sonic vibration was also incorporated into this device to augment the compaction and obturation effectiveness of EndoTwinn’s heated tips.

Several studies have reported that by simultaneously combining the efficacy of heating the obturating material combined with sonic vibration to help the plasticized gutta-percha flow, the average percentage of gutta-percha in the canal space could increase significantly, especially in the more narrow tapered canals.^10-12 In early 2007, efforts to improve and refine the EndoTwinn led to the introduction of the DownPak (Hu-Friedy). The DownPak enables the clinician to employ variable temperature settings and to turn on or off the vibration feature, as desired.¹³ The variable temperature settings become useful when different obturation materials are used. For example, Resilon softens at a lower temperature than gutta-percha. The DownPak is cordless and lightweight, with an ergonomically balanced hand-held grasp; all of the switches and adjustments are easily accessible on the handle (Fig. 1).

Fig. 1: The DownPak is a self-contained device that transfers heat and vibration to a spreader or plugger tip. All of the controls are easily accessible on the handle.

Technique

The use of the DownPak is similar to a combined vertical and lateral compaction of gutta-percha, so the clinician familiar with these techniques should find the device very user-friendly. First, the appropriate DownPak tip is selected so that it reaches a depth in the canal that is 3.0–5.0 mm from the apical terminus. A silicone stop can be adjusted on the tip as a reference point for this measurement (Fig. 2a). Next, the canal walls are coated with sealer and a master gutta-percha (or Resilon) cone is placed in the canal to working length. Using the tip of the heated DownPak, excess coronal gutta-percha is removed to the level of the orifice (Fig. 2b). With a sustained push, the DownPak tip is introduced into the canal with the heat and vibration modes activated. The tip is then extended down the canal space to the predetermined binding point, 3.0–5.0 mm from the apical terminus (Fig. 2c). The tip is rotated rapidly two or three times 180 degrees clockwise/counterclockwise and heated for two to four seconds; at that time the tip is removed quickly along with any excess gutta-percha (Fig. 2d). Any remaining voids can be sealed coronally with additional accessory cones by applying vertical compaction as described above. Although radiographs are only two dimensional, the clinical cases depicted in Figures 3 and 4 give an indication of the clinical effectiveness when obturating canals with the DownPak.

Figs. 2a–2d: The appropriate DownPak tip is selected so that it extends 3.0–5.0 mm from the apical terminus. A silicone stop on the tip is adjusted as a reference point (Fig. 2a). Canal walls are coated with sealer and a master gutta-percha (or Resilon) cone is placed in the canal to working length. Using the tip of the heated DownPak, excess coronal gutta-percha is removed to the level of the orifice (Fig. 2b). The DownPak tip is introduced into the canal to the predetermined binding point with the heat and vibration modes activated for two to four seconds. The tip is rotated rapidly two or three times 180 degrees clockwise/counterclockwise and heated for two seconds (Fig. 2c). The tip is removed quickly along with any excess gutta-percha. Remaining voids are sealed coronally with additional accessory cones by applying vertical compaction as described above (Fig. 2d).

Figs. 3a–3c: Pre-operative radiograph of maxillary right second pre-molar. Note apical dilacerations and periradicular bone loss (Fig. 3a). Immediately after obturation. Note the lack of voids and the lateral canal filled on the mesial (Fig. 3b). Five months post-endodontic treatment. Note the remineralization in the area of the periradicular bone (Fig. 3c).

Figs. 4a–4d: Pre-operative radiograph of mandibular left first molar (Fig. 4a). Working length radiograph depicting four canals, each with a separate apical terminus (Fig. 4b). Immediately after obturation (Fig. 4c). Six months post-endodontic treatment. Note favorable periradicular bone healing (Fig. 4d).

Summary

The literature and this article have documented the benefits patients receive when clinicians employ plasticized gutta-percha and vertical compaction combined with vibration. The advent of cordless devices like the DownPak make it easier for the clinician to more effectively provide a three-dimensional obturation.

Editorial note: This article was originally published in Endo Tribune US, Vol. 3, Issue 7, 2008.

Contact info

Dr Cohen is on the advisory board of Hu-Friedy Co.  He can be reached at scohen@unionsquareendo.com.

Dr Berman may be contacted at Berman@AnnapolisEndodontics.com.

Dr Martin may be contacted at gmartin@endocordoba.com.