Tuesday, October 16, 2007

Endodontic solutions

Dr Richard Mounce answers some common questions that crop up in relation to reading radiographs and their clinical implications.

Knowing what clinical challenges one will be confronted with in a case is essential. Radiographs provide the information to visualise anatomy which otherwise obviously would not be seen.

Reading the radiograph properly and interpreting all the information present is an essential skill. Ideally, the clinician will take three radiographs pre-operatively before beginning treatment, one from the mesial, one from the distal and one from the buccal (straight on). Doing so can give the clinician the best possible visualisation of the tooth in terms of mapping the canal system and determining the challenges that it will present.

Having a digital radiography programme like Dexis (Dexis Digital Radiography, Alpharetta, GA, USA) can make a significant difference in gathering information rapidly and accurately without the delays of processing, and also gives the added benefit of being able to manipulate the images with software to obtain the optimal diagnostic information. Bearing this in mind, there are common clinical questions that general practitioners often have regarding radiographs whose answers have clinical application:

Immediate treatment?
1) If a tooth has a pathologic lesion and is asymptomatic (no pain, swelling, tissue changes, etc), does it need treatment immediately?

Empirically, I am confident the vast majority of endodontists would say yes, that once the tooth has a clearly defined periapical lesion, and a diagnosis of non-vital pulp is made and confirmed with cold testing and other objective tests as needed, the tooth should be treated as soon as possible.

Such a tooth, even though it is asymptomatic now, can become severely painful and the patient swollen quite rapidly, often without warning. Management in such an urgent scenario is often more complex than otherwise might have been needed had the tooth been treated comprehensively at the initial visit where the lesion was observed and the diagnosis of non-vital pulp confirmed while the patient was asymptomatic. Most often, these clinical cases will and should be treated in two visits. Two-visit management is beyond the scope of this article.

Lesions present?
2) What if the radiograph is unclear and I am not sure a lesion exists but I suspect one? If the patient is asymptomatic, what are the clinical considerations of such a finding?

Before answering the question directly, it must be advised to have the clinician look along the entire attachment apparatus for evidence of pathology. Lesions form opposite the portals of exit (lateral canals) and it is certainly possible that lesions can be found mid root at the lateral root surface and also in the furcation. In other words, clinicians must assure themselves that they have evaluated the totality of the radiograph.

This question should be broken down into its component parts. First off, the pulpal status of the tooth must be defined to the best of the clinician’s ability. The tooth must be tested to percussion, palpation, mobility, probing, cold, hot and EPT as needed. In addition, the presence of caries, coronal fractures, deep fillings, wear patterns due to bruxism, etc, must be considered. The periododontal status of the tooth must be addressed. How much bone support is available, are there mucogivingival defects, and are there boney defects, etc?

The restorability of the tooth should also be evaluated. How much coronal tooth structure is present? Is the tooth tipped? Is the tooth a strategic and vital tooth for future restorative treatment plans? The canal needs also to be evaluated. Is the pulp space calcified? Are there pulp stones in the chamber? Is the bone sclerosed apically even though their presence or absence of a periapical lesion cannot be confirmed?

In essence, these questions can collectively form the basis of a comprehensive evaluation of the tooth’s status. As such, it can tell the clinician if the tooth should have root canal treatment and makes the periapical radiograph often an ancillary instead of primary piece of evidence, which in fact, it is. In the most general terms, if the tooth is restorable, has strategic significance, and there is real and confirmed doubt as to the health of the pulp, especially if the tooth is to be restored with a crown or be made a bridge abutment, it should be treated.

Many is the tooth that has been watched for so long that the entirety of the pulp space has been obliterated until the canal or canals are no longer negotiable even with the smallest hand files. Many is the new bridge or crown that has been accessed after its placement when clear signs and symptoms were present before its placement. In my opinion, this is supervised neglect. It happens all too often as some clinicians may delay treatment or referral with the misguided wisdom that ‘if it aint broke, don’t fix it.’

It should also be remembered that lesions can be present in bone without being radiographically visible. The bone destruction must perforate the cortical plate to be
radiographically visible; the radiographic absence of a lesion does not mean that one is not there. In summary, if the tooth is non-responsive to cold and the pulp space is narrowing and the other strategic importance and value factors are present, most often serious consideration should be given to treat the tooth to preserve its long-term value to the patient and restorability, irrespective of the appearance of the radiograph.

Indicator of difficulty?
3) The canal appears calcified, what does that tell me about how challenging the endodontic procedure might be? Does the degree of calcification really translate to a harder endodontic procedure?

Under a surgical microscope such as the Global SOM (Global Surgical, St. Louis, MO, USA), identifying the canals after making a straight-line access is not generally difficult. How wide the orifice of such a canal is made is far more a factor with regard to how challenging the tooth will be rather than how narrow the canal is initially.

Said differently, a canal that is relatively wide open can be blocked rapidly if it is mishandled and the debris present in the canal is pushed apically rather than being lifted apically. In essence, the radiographic appearance of the canal is an indicator of potential difficulty but it is not in and of itself an assurance of a clinically challenging case.

Inherent in such cases is the extreme importance of moving down the canal gently and slowly with small hand files such as #6 and 8 hand K files and only taking these files down the canal to the level where they will be easily accepted. The Pathfinder CS files are excellent for this initial negotiation (SybronEndo, Orange, CA, USA).

An RNT file is not to be placed into such a canal until the canal is open, negotiable and a glide path has been created. Patience is the watchword as clearly defining the canal path and its negotiation is key for utilising the RNT to its greatest efficiency.

Once a canal can be negotiated fully to its greatest apical extent (i.e. the estimated or true working length) with a hand K file such as a 6, 8 or 10, it can be attached to an M4 reciprocating handpiece (SybronEndo, Orange, CA, USA). With a 1-2 mm amplitude, the M4 can, with reciprocating movement of the file, rapidly enlarge a narrow and calcified canal easily and safely, reducing hand fatigue and saving substantial time. As a precursor a RNT file system like K3 (SybronEndo, Orange, CA, USA), enlargement of canals with a hand K file with an M4 reciprocating hand file can go far toward efficiently and quickly creating the needed glide path for RNT enlargement.

M4 use is enhanced through the use of a viscous EDTA solution like File-Eze (Ultradent, South Jordan, UT, USA), which can hold the pulp in suspension as the canal is enlarged and lubricate the canal. After each use of the M4, the File-Eze can be flushed out with sodium hypochlorite, the canal recapitulated and the File-Eze reapplied.
I welcome your feedback.

Author : Richard Mounce

Dr Richard Mounce lectures globally and is widely published. He is in private endodontic practice in Vancouver, Washington, USA. Amongst other appointments, he is the endodontic consultant for the Belau National Hospital Dental Clinic in the Republic of Palau, Micronesia. He can be reached at RichardMounce@MounceEndo.com. Dr Mounce has no commercial interest in any products of any kind.