Canal projection using gutta-percha points: A novel technique for pre-endodontic buildup of grossly destructed tooth.

The use of Projector Endodontic Instrument Guidance System (PEIGS) during endodontic treatment of grossly mutilated tooth facilitates projection of canal orifices from the floor of the pulp chamber to the cavosurface, providing direct visualization and access to the projected canals. Alternatives, such as hypodermic needles as sleeves, were tried successfully with similar outcome. The aim of this case report is to describe a simpler, easily available, economical, yet an effective alternative technique to conventional PEIGS during the pre-endodontic management of grossly destructed tooth. These case reports demonstrate the use of greater tapered gutta-percha points that are easily available and more economical than PEIGS for the successful management of a badly destructed tooth.

INTRODUCTION

With increased awareness of patient safety, technique-sensitive dental materials, infection control, and meticulous operative conditions, isolation of teeth is mandatory in contemporary dentistry. Currently, the rubber dam is the “Standard of Care” for isolation during endodontic treatment and restorative procedures should be employed whenever possible.[12]

Grossly mutilated tooth often pose problems to endodontic treatment during rubber dam clamp placement. Isolation can be effectively done in these cases with the help of gingivally approaching clamps; clamps with serrated jaws are known as tiger clamps and special clamps, for instance, Silker-Glickman (S-G) clamps.[3] Maintaining root canal patency while isolating grossly destructed tooth with open pulp chamber is a great challenge to an endodontist, without blocking the root canals with restorative material. This can be effectively achieved by canal projectors suggested by Gerald N Glickmann and Roberta Pileggi in which tapered plastic sleeve is used to maintain the canal patency.[4] Due to limited worldwide availability of the original canal projection system, alternatives, such as hypodermic needles as sleeves, were tried successfully.[5]

This article describes a much simpler, easily available, economical, yet an effective alternative technique to conventional projection system during pre-endodontic management of grossly destructed tooth with open pulp chamber, without resulting in any canal blockage.

Alternative technique

The following section describes an indigenous alternative technique to the original PEIGS[6] and two case reports of endodontic management of a grossly destructed tooth by using greater tapered gutta-percha points as canal projectors.

The indigenous technique is as follows: After access preparation under suitable isolation, root canal orifices are located and the patency of canals is verified with size 10 K file. Coronal 4-5 mm of orifices is enlarged with greater tapered orifice shapers such as Protaper SX. Greater tapered gutta-percha of suitable sizes is selected and placed into the orifices such that each gutta-percha point extends at least 4 mm into the root canal. If any small gap exists between the canal orifice and gutta-percha point, it has to be closed by softening gutta-percha with a heated plugger, adjusting it close to the walls of root canal, such that none of the restoring material flows into the canal and blocks it. One or more gutta-percha points with different sizes and tapers may be needed to close the orifice, for dumbbell-shaped canals. A circumferential matrix system, such as tofflemire, should be applied to the remaining tooth structure to serve as an artificial, temporary wall during the buildup. This is not needed in cases where all the walls are intact and sound. Acid etching and bonding should be performed according to the manufacturer's recommendations. Flowable resin may be used to build the initial layers and subsequent layers with hybrid composite. Following final curing, the gutta-percha projectors can be removed by slight watch wind motion. If there is any difficulty in removal of gutta-percha projector, a heated H file or a gutta-percha solvent may be used effectively to remove it. The adjustment of occlusal surface may be needed to provide ideal endodontic reference points. The final result of this pre-endodontic buildup is a stable coronal structure with straight-line access into each canal from the occlusal table allowing effective rubber dam isolation similar to the result that can be achieved using the original canal projection system.

CASE REPORTS

Case report 1

A 40-year-old male patient was referred to an endodontist by a general dentist after unsuccessful attempt to locate root canals of mandibular first molar. After removal of temporary restoration from access cavity, necessary modification of access preparation was done to locate root canal orifices under cotton role isolation [Figure 1a]. Patency of root canals was confirmed with size 10 K file after rubber dam placement [Figure 1b]. Coronal 4 mm of orifices were enlarged with orifice shapers such as Protaper SX (Dentsply Maillefer, Ballaigues, Switzerland). Greater tapered gutta-percha of suitable sizes were selected and placed into the orifices such that each gutta-percha point extended at least 4 mm into the root canal. In this case, F2, F3, and F4 Protaper gutta-percha points (Dentsply Maillefer, Ballaigues, Switzerland) were selected for mesiobuccal, mesiolingual, and distal canal orifices, respectively. Small gaps between the canal orifices and gutta-percha points were closed by softening the gutta-percha with a hot plugger and adapting it to canal walls with a cold plugger. A matrix system was not needed in this case since all the walls, nevertheless thin, were intact. Acid etching of entire pulp chamber with 37% phosphoric acid (Scotchbond Etchant gel; 3M ESPE, St Paul, MN, USA) was done to etch the exposed dentine and enamel. After 30 s, rinsing and drying were accomplished. Dentin bonding (Adper Single Bond, 3M ESPE, St Paul, MN, USA) was applied according to the manufacturer's recommendations and was light cured. Dual cured flowable resin (Filtek™ Z350XT Flowable Restorative, 3M ESPE, St Paul, MN, USA) was used to build the initial layers, and subsequent layers were built with hybrid composite (Filtek™ Z350XT Universal Restorative, 3M ESPE, St Paul, MN, USA) [Figure 1c]. Following the composite curing, the gutta-percha projectors were removed by a heated H file. A high speed diamond bur was used to level the occlusal surface to provide ideal endodontic reference points [Figure 1d]. The final result of this pre-endodontic buildup was a stable coronal structure with straight-line access into each canal from the occlusal table [Figure 1e] with maximum structural reinforcement allowing easier and effective rubber dam isolation with a stable four point contact of rubber dam clamp. Working length was determined and pulpectomy was done [Figure 1f]. Integrity of the composite buildup was maintained throughout the treatment, allowing the easier and effective rubber dam isolation during subsequent visits of shaping, obturation, and 12 month follow-up [Figure 1g–i].

Figure 1

(a) Access preparation of mandibular first molar showing root canal orifices (b) Radiograph showing rubber dam clamp placement on mandibular first molar (c) Protaper gutta-percha points as indigenous canal projectors and composite buildup (d) Composite buildup after removal of indigenous canal projectors (e) Radiograph showing composite buildup after removal of indigenous canal projectors (f) Working length radiograph of mandibular first molar under rubber dam isolation (g) Master cone radiograph of mandibular first molar under rubber dam isolation (h) Postobturation radiograph of mandibular first molar under rubber dam isolation (i) Twelve-month follow-up radiograph of mandibular first molar

Case report 2

Access preparation of mandibular right first molar of a 32-year-old female patient under cotton roll isolation resulted in a subgingival extension into free gingiva on lingual surface, making it difficult for rubber dam isolation [Figure 2a]. After coronal enlargement of orifices with orifice shapers, greater tapered gutta-percha of suitable sizes were placed into the orifices such that each gutta-percha point extended at least 4 mm into the root canal. An ultrathin metal matrix band was placed to replace the lost lingual wall, extending atraumatically into the free gingiva [Figure 2b]. Any gaps between the canal orifices and gutta-percha points were closed by softening the gutta-percha. After acid etching, rinsing, and drying, dentin bonding was applied and light cured. Dual cured flowable resin was used to build the initial layers, and subsequent layers were built with hybrid composite [Figure 2c and d]. After curing the last increment, the gutta-percha projectors were removed by a heated H file. Occlusal surface was made flat to provide ideal endodontic reference points [Figure 2e]. This pre-endodontic buildup resulted a stable coronal structure with a straight-line access into each canal and allowed easier and effective rubber dam isolation. Working length was determined under rubber dam isolation and further treatment was carried on [Figure 2f].

Figure 2

(a) Access preparation of mandibular first molar showing root canal orifices (b) Matrix band placement and selection of indigenous canal projectors (c) Protaper guttapercha points as indigenous canal projectors and composite buildup (d) Radiograph showing indigenous canal projectors and composite buildup (e) Composite buildup after removal of indigenous canal projectors (f) Working length radiograph of mandibular first molar under rubber dam isolation

DISCUSSION

The preservation of a grossly destructed tooth by endodontic treatment, if possible, is a superior and universally preferred mode of treatment to tooth extraction and replacement.[7] This preservation has to be done under rubber dam isolation since it reduces aerosol contamination and cross infection by up to 98.5%.[8]

Grossly mutilated teeth with subgingival carious lesion, tooth with little cervical tooth structure, and deep carious teeth with open pulp chamber are often challenging to endodontist, due to difficulties in isolation of tooth under rubber dam, maintaining canal patency, restoring the lost tooth structure, and controlling salivary leakage in between appointments. Techniques, such as “split dam technique,” using a clamp with prongs inclined gingivally; gingivectomy; crown lengthening procedures; and clamp stabilization by placing it on attached gingiva, are some of the methods used to isolate the tooth in these conditions. However, these methods will not provide the same level of moisture control, safety, and comfort to the patient that a rubber dam can provide.

Pre-endodontic buildup of lost coronal structure following caries removal provides a strong core, good coronal seal, and a reservoir for irrigating solutions during canal instrumentation, as well as simplifies atraumatic placement of rubber dam clamps during the subsequent visits. Pre-endodontic buildup may be performed with variety of materials such as amalgam, composites, or glass ionomer cements. This can be facilitated by the application of copper bands, orthodontic bands, or temporary crown forms. If any minor leakage occurs, it can be managed by sealing it with Cavit, Oraseal, or “liquid dam.”[9] Surgical exposure of subgingival tooth structure to aid clamp placement, usage of serrated clamps, clamps with gingivally oriented prongs are helpful during isolation of severely destructed tooth. Usage of orthodontic bands, pin retained amalgam, and adhesive restorations are also advocated.[10] But these methods have some inherent disadvantages such as difficulty to master, technique sensitivity, inferior sealing ability, and poor retention of coronal buildup.

Pre-endodontic buildup of grossly destructed tooth with open orifices, at times, may result in blockage of root canal orifices as some amount of restorative material may be pushed unintentionally into the root canal, which compromises thorough cleaning and shaping of root canal system, resulting in suboptimal outcome. Canal projection system minimizes these kinds of mishaps to a greater extent by closing the canal orifices, thereby no restorative material displaces into the canals during the pre-endodontic buildup. In addition to these advantages, the canal projection system provides added advantages such as better sealing of chamber floor, proper orientation, and easier insertion of rotary instruments into the canals, especially in the case of smaller tooth where the canal orifices are closely located and also in cases where the dentinal mapping is lost because of iatrogenic nicking of pulp chamber floor. It also aids in sealing of the furcal perforation and its maintenance during subsequent visits, recontouring the irregularities on chamber floor and walls, lengthening the root canal, thereby resulting in better hydraulic condensation during warm vertical compaction.

This indigenous technique of canal projection with greater tapered gutta-percha points offers all the benefits of conventional PEIGS, without any extra learning curve. This novel alternative method is an easily available, economical, yet equally effective alternative for original canal projection technique using PEIGS.

CONCLUSION

Rubber dam isolation of grossly destructed teeth with minimal supragingival structure is a challenging task during the endodontic treatment. The indigenous canal projector system not only provides perfect isolation but also offers other advantages such as easier orientation of files to canals, serves as good foundation restoration, facilitates reconstruction of the lost walls and floors, and acts as “hydraulic chamber” of each canal, offering advantages during the hydraulic condensation of obturating materials. These case reports demonstrate the use of gutta percha (GP) as a canal projector which is an effective alternative to PEIGS.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.