Management of Partially Obliterated Root Canals –Report of Two Cases

Introduction

Pulp canal obliteration is defined as “a pulpal response to trauma characterized by rapid deposition of hard tissue within the canal space” by the American Association of Endodontists. It is also known as calcific metamorphosis, dystrophic calcification and calcific degeneration.¹ Pulp canal obliteration occurs due to dental trauma, caries, abfraction, abrasion, pulp capping, occlusal imbalance, orthodontic treatment, harmful oral habits, any of which may manifest as a chronic low grade stimulus.²

The primary objective of endodontic therapy is to reduce or eliminate microorganisms and their by-products from the root canal system. This can be achieved to a great extent by thorough chemo-mechanical debridement, disinfection and obturation of the root canal system. However, this procedure may be difficult to achieve if the pulpal space is obliterated, narrow or calcified. In root canals of teeth in which calcific deposits have blocked access to the canals, treatment efforts are often difficult.

An effort to locate the residual canal may remove large amounts of dentin and there is a risk of perforating or fracturing the root.³

This article presents management of two cases with partially obliterated root canals due to dental caries and ageing with second generation rotary glide path instrument ProGlider to create effective glide path before using NiTi rotary shaping instruments, thereby achieving the major objectives of endodontic therapy.

Case Report 1

A 44-year-old female patient reported with a chief complaint of pain for duration of one week in the upper left first molar. On clinical examination, dental caries was noted in 26 and pain on percussion was present. Diagnostic radiograph was taken and endodontic treatment was advised. Radiographic examination showed partial root canal obliteration which may be due to dental caries acting as a low-grade stimulus. (Figure 1)

Rubber dam was placed and stabilized with widgets. A standard access cavity preparation was initiated with high speed round bur. DG -16 explorer was used to locate the root canal orifices. #8 size k file was used along with 17% EDTA to explore the canals. The file was introduced in the canal and resistance was felt at approximately middle third of the canal. Now No.10 size k file was used up to the working length. Later ProGlider (DENTSPLY) was used with 300 rpm at 2N along with 17% EDTA and a glide path was created at the calculated working length. Frequent inspection of the file was done to avoid iatrogenic errors and frequent irrigation of the canals was done with saline and 5% Sodium hypochlorite. Then NiTi rotary instruments i.e. orifice sharpener and 20 -4% instrument of Hyflex CM (Coltene Whaledent) was used for cleaning and shaping of the canals. Master cone IOPA was taken (Figure 2 & 3) and the canals were obturated with 20-4% gutta percha.

Case Report 2

A 68-year-old male patient reported for restoration of missing tooth in the lower anterior region. On clinical examination, 31 was found missing and 41 was found to be having grade 3 mobility. Patient was advised for extraction of 41 and crown and bridge was planned with 32 and 42 as abutment. Intentional endodontic treatment was advised for 32 and 42 followed by crown and bridge.

Radiographic examination showed partially obliterated root canal (Figure 4). A standard access cavity preparation was initiated with high speed round bur and the working length was calculated as 25 mm. No.8 size K file along with 17% EDTA was used to explore the canal in 32 and 42 till resistance was felt. Then 25 mm ProGlider was used according to the manufacturer’s instructions followed by orifice sharpener and Hyflex CM NiTi rotary instruments and obturation was done. (Figure 5 & 6)

Frequent and alternate irrigation with saline and sodium hypochlorite was done. All the files were regularly inspected for irregularities after use.

Discussion

The success of endodontic treatment of partially obliterated canals depends on careful location of orifice, creating a glide path, proper biomechanical preparation and obturation of root canal system. The etiology of pulp canal obliteration is not well understood but it is often attributed to age, deep restorations, long term standing trauma.⁴

Certain systemic conditions such as Osteodystrophy, Atherosclerosis, Marfan Syndrome and some orthodontic cases where intrusive movements can cause compression of the apical vessels can also cause pulp canal obliteration.⁵

Diagnostic radiograph plays an important role in the management of these root canals. Radiographic obliteration of pulp canal space can be classified as: ⁶

1. Partial obliteration- the pulp chamber is not visible and the canal is markedly narrowed but visible.⁷

2. Total obliteration- the pulp chamber and canal is hardly or not visible.

The above two case reports had partial obliteration where the pulp chamber is not visible and the canal is markedly narrow on radiographic examination. There are a wide range of glide path instruments available to be used in different motions and techniques, which can be broadly categorized under three categories viz., manual, rotary and reciprocating glide path instruments.⁸

Even though manual glide path preparation with stainless K files have excellent tactile sensation, cost effective when compared to other glide path files and no specific handpiece required during their use,^9,10 Piston action of K files with push and push motion results in increased apical debris extrusion¹¹ and time consuming during preparation of glide path and also results in hand fatigue.¹²

When using hand files in reciprocating handpiece, although time required is less for glide path preparation, it requires special handpiece¹⁰ and has increased chance of apical debris extrusion, if handpiece is inserted apically with force.¹³

Studies using Micro- CT analysis have evaluated the variation in canal anatomy after creating a glide path both manually and mechanically. One such study confirmed that a mechanical glide path (PathFiles) preserves the original anatomy of the canal with significantly improved results and fewer canal abnormalities when compared to manual glide path.¹⁴ But NiTi instruments despite their excellent quality, pose a risk of unexpected fracture. So next generation NiTi glide path rotary instrument was developed with M wire technology and R phase which is the intermediate phase with rhomboid structure that forms during the transformation from martensite to austenite and vice versa.

ProGlider15 is a single-file, single-use glide path file with diameter 0.16 mm at D0 and 0.82 mm at D16 and increasing taper from 2% to over 8% along its active position, made up of M-wire alloy and has square cross section with semi active tip. A progressively tapered design over the active portion of a single file reduces the potential for taper lock and screw effect.

These two cases were managed with No.8 size and No.10 size k files to the working length followed by using ProGlider to create the glide path, followed by NiTi rotary shaping instruments and final obturation was done with gutta-percha.

Conclusion

The cases presented here are examples of management of radiographically partially obliterated canals with absence of distinct pulp chamber and a markedly narrow canal. The endodontic glide path is the key to endodontic success and also increases the longevity of rotary NiTi instruments. When done properly, it reduces the possibility of instrument separation and other procedural errors which can happen during the use of rotary shaping instrument. Good knowledge of internal anatomy of tooth to be operated and a skilled operator with proper armamentarium are the key factors in nonsurgical management of these canals.

Disclaimer

The author has not received any monetary benefits from the trademark companies to which the instruments mentioned in this article belong to.

Conflict of Interest

None.