Recently, I received these two questions from the same reader. The answers have clinical application for all clinicians who practice endodontics. These questions underscore the importance of understanding the causes of pulpal inflammation as well as the basic indications for endodontic therapy with a diagnosis of irreversible pulpitis (IP).
The onset of an IP is correlated with, amongst many mechanical, traumatic, erosive, and microbial insults:
1) the depth of the fillings
2) the number of fillings
3) the type of filling material
4) how much water spray was used in preparation
5) the type of bur used
6) periodontal disease and lost attachment
7) the pulp was exposed and how the exposed pulp was treated
8) the tooth has coronal fractures
9) the dentin was acid etched
10) an impression has been taken
11) chemicals and adhesives were used to treat/bond the dentin
12) there is occlusal trauma
13) a crown has been cemented.
This list is by no means exhaustive. In short, the greater the number of additive factors over time that have contributed to the cumulative pulpal trauma, the greater the chance that the pulp may become irreversibly inflamed.
Symptoms of IP include:
1) pain that is spontaneous
2) pain that is lingering to hot or cold
3) severe pain to hot or cold that may or may not linger
4) pain to chewing (most especially accompanied by pain to hot or cold).
"I... need your help... Lingering pain is described as irreversible pulpitis. Is there any cutoff value in terms of time duration that differentiates between reversible and irreversible pulpitis, i.e. pain lingering for 10 seconds might be irreversible pulpitis whereas if it lingers for less, it's reversible?"
"In addition to this, please respond to following related clinical scenario:
A male patient of 35 years presents with pain and sensitivity in his left maxillary first molar. The symptoms appear on taking cold only and remain for five minutes. The radiograph shows a deep carious lesion and no periapical pathology. Tooth is not tender to percussion. The patient is suffering from:
A- Reversible pulpitis
B- Irreversible pulpitis"
Answer to question 1
The short answer is no, there is not a "cutoff value."
The more expanded and clinically relevant answer is that symptoms from irreversible pulpitis (IP) do not occur in a vacuum and virtually all such cases have signs, symptoms and clinical findings that are part of a larger set of findings spread over time. Very often, for example, patients who have lingering pain to hot or cold, irrespective of how long the lingering, tend to have had recent fillings or crowns on the offending tooth at some point in the past 6-12 months. Commonly, after the restoration, there is often ongoing pain of varying intensity almost immediately after the placement of the restoration.
Answer to question 2
Conclusively, this is an IP. The presence or absence of periapical pathology is not directly relevant to the diagnosis in this case. A patient with deep caries has had bacterial insult to the pulp. Sensitivity to cold for 5 minutes is a certain indication that the pulp is irreversibly damaged and will not recover. The fact that the tooth is not sensitive to percussion only tells us that the inflammation has yet to spread to the periapical tissues. It must be remembered that pulps die in a coronal to apical direction. In this clinical case, the pulp within the canal is irreversibly inflamed but without complete necrosis and apical symptoms. If the pulp were left, it would eventually die and toxic byproducts of this breakdown enter the apical tissues, cause inflammation, and eventual infection.
In the clinical case cited, it is somewhat unusual for a patient to only have a chief complaint of lingering sensitivity to hot or cold. Hot and cold sensitivity is usually accompanied by other symptoms, spontaneous pain and/or pain to chewing. It is possible for the patient or clinician to be lured into a false sense of security, if after spontaneous pain, the tooth becomes comfortable. In the patient's mind, such comfort often means that they have healed.
If the symptoms of IP were to disappear without treatment, it is a virtual certainty that the pulp is becoming less vital or has lost vitality. In time, if left long enough, the patient will have some combination of the following: 1) obvious radiographic pathology 2) possible swelling, 3) pain (usually a deeper and more dull pain, unlike the sharper pain noted with an irreversible pulpitis).
It is my empirical observation that too often clinicians wait and delay treatment on teeth with obvious symptoms of IP. It is common, unproductive, and hopeful to wish that the pulp would heal in the presence of definitive IP symptoms. Unfortunately, in endodontic offices, often multiple times per day, patients present with IP who have been observed for some length of time. Often, there are symptoms of IP that are ignored either before, during and after a new restoration is cemented (Fig. 1). Patient trust can be lost when a new restoration has to be accessed. Early intervention can minimize the number of teeth that need access through new crowns or bridges risking their fracture or need for repair and/or replacement.
Leaving pulps that are stressed and irreversibly inflamed to smolder without treatment leads to calcified canals and pulp chambers as a protective mechanism. In chronic cases, location, negotiation and enlargement of the canal space is often much more difficult due to calcification that can arise from long-term neglect of a slowly dying pulp. Management of such challenging cases predisposes the clinician to a much higher possibility of iatrogenic outcomes in endodontic treatment.
Not all asymptomatic calcified canals require arbitrary treatment. The astute clinician will test teeth to cold periodically if it appears that the pulp is calcifying and be especially aware of pulpal health if the tooth needs a significant new restoration. If there is any doubt as to the health of the pulp and a strategic restoration is planned, it is usually wiser to perform the root canal rather than have to access through a new restoration later.
It is counterproductive to wait and hope that the patient will get better once these signs and symptoms of IP have been demonstrated. Many is the patient who has been denied treatment or had treatment delayed because their clinician "does not see anything on the x-ray." It must be remembered that IP is not manifest on an x-ray and as such must be diagnosed from the patient's symptoms and clinical examination. Usually, this is not challenging. At the stage of IP, the radiograph often does not show any changes, even subtle ones. Radiographic evaluation on a paper film from one angle is not as reliable as multiple digital images (DEXIS, DEXIS digital radiography, Alpharetta, GA, USA). In my empirical opinion, digital radiographs taken from multiple angles can provide the greatest degree of accuracy in determining if apical changes have taken place and aid in the diagnosis of IP.
The case illustrated in Figure 2 is a case in point. The patient was treated August 9th 2007 for a DO composite filling and subsequently developed severe and increasing pain to cold that lingered and within days became spontaneously painful. The occlusion was adjusted and the patient told that the tooth should improve. Endodontic treatment was never mentioned as an option. The pain continued until August 29th 2007 when the patient reported to my office with a chief complaint of severe pain to cold and nocturnal pain. RCT was carried out the same day and the patient's pain resolved immediately. It was clear within days after the restoration that the tooth needed a root canal, waiting simply kept the patient needlessly uncomfortable until treatment was rendered.
MANAGEMENT OF IP CLINICALLY
Anesthesia is often a challenge in severe cases of IP. Excellent and profound anesthesia is essential and must be without compromise. While a discussion of anesthetic techniques is beyond the scope of this article, whether it is through intra osseous techniques, waiting long enough for injections to effective, hitting correct landmarks, using the right volume of anesthetic, etc the patient must be profoundly numb to treat a true IP, especially on a lower molar. Use of an intra osseous anesthetic delivery system such as IntraFlow (Pro-Dex Motors, Santa, Ana, CA, USA) can be invaluable in quieting a recalcitrant tooth.
Adequate explanation of the procedure and consent from the patient are essential once a diagnosis and localization of the offending tooth has been accomplished through the required testing and history. It is essential to reproduce the patient's symptoms to make certain that the offending tooth is correctly identified. Reproducing the symptoms means that if the patient has pain to cold, that cold is used to elicit the same response as the one that is creating the patients chief complaint. For example, if the patient says that #30 is painful when drinking cold fluids and localizes the pain to that tooth, application of cold should elicit the same response as what the patient reports. The diagnosis should be verified by testing the teeth around #30 and the contra lateral tooth. The teeth should test within normal limits and #30 should respond in the manner reported.
Once a comprehensive assessment is made of the initial radiographs to determine the anatomical complexity of the tooth, access may begin. A rubber dam is mandatory. A surgical operating microscope provides optimal magnification and visualization of the entire process (Global Microscopes, Global Surgical, St. Louis, MO, USA). It is difficult to overstate the advantage the SOM gives the clinician in managing access, canal location, and obturation as part of the larger endodontic procedure.
As soon as the pulp chamber is unroofed and all the canal orifices are located, use of a viscous EDTA gel is advised (Endo-Eze, Ultradent, South Jordan Utah, USA). Endo-Eze acts as a lubricant and to hold the pulp in suspension and not allow tissue to be propelled apically as orifice openers and files begin coronal enlargement.
The K3 orifice "Shapers" are ideal instruments with which to perform early enlargement of the coronal aspect of the root to the first significant root curvature (SybronEndo, Orange, CA, USA). Pulpal necrosis occurs in a coronal to apical direction explaining the mechanism for pain relief in IP cases. Removal of the pulp from the chamber and coronal third eliminates by volume, a significant amount of the total pulp and predictably resolves the immediate symptoms of IP. The Shapers are used from larger tapers to smaller, .12 to .10 and .08 (the Shapers have a fixed tip size of 25) in a canal in which they are accepted passively. Passively is the key term. The Shapers should not ever be forced into an orifice or pushed apically where greater force is placed upon them than the clinician would put on a #2 pencil. It is axiomatic that the clinician should make sure that the canal is open, patent, and negotiable to at least a #15 hand file before Shaper insertion. Some narrow canals will require multiple short insertions to the point of greatest curvature in the root, some open and straight canals (an upper canine for example) may allow the Shapers into the apical third easily and do so in one pass of the instrument. In any event, for most teeth it is simple to remove the coronal third pulp with an orifice opener such as the Shaper (Fig. 3).
The K3 Shapers are relatively flexible given their taper, cut very well, and are quite durable. To power the K3 Shapers, the TCM III electric motor provides an excellent stand alone motor for corded electric motor needs (SybronEndo, Orange, CA, USA). The ELECTROtorque TLC (Kavo, Lake Zurich, Il, USA) is an excellent option for a comprehensive handpiece solution. It provides an electric high speed, low speed and endodontic motor function all wired into one box on the dental unit. Both of these units have the RPM and torque capabilities to maximize the function of the K3 Shapers and any RNT system. I rotate all of my K3 files (including the Shapers) at 900 RPM or higher depending on the clinical indication. Fig 4.
The final prepared taper at the orifice created by a .12 tapered Shaper is very well suited to the application of a flowable composite such as PermaFlo* which can be injected into the orifice of the coronal 1-2 mm of the canal with a Skini Syringe* and various needle tips (*Ultradent, South Jordan, UT, USA) (Fig. 5).
SINGLE VISIT TREATMENT FOR IRREVERSIBLE PULPITIS
Once the pulp chamber has been cleaned and the coronal third shaped, can a case be completed in one visit with a diagnosis of IP? If the root canal system can be cleansed, shaped, and obturated properly with a diagnosis of IP, there are no contraindications to completion in one visit. Completion in one visit leads to efficiencies in treatment. As a practical matter, if the clinician has anesthetized the patient and removed the coronal pulp down to the middle third of the root, it is often a relatively simple matter to finish the procedure if done correctly.
Cleaning and shaping should be carried out crown down, meaning that the coronal third should enlarged first, the middle third second and the apical third last. Once straight-line access has been accomplished and the coronal third enlarged ideally, subsequent shaping can proceed.
In summary, a comprehensive clinically relevant discussion of irreversible pulpitis has been presented which emphasizes early diagnosis and definitive treatment.