The Endo Fix

Category: Deep Fix

Root Form Appropriate Instrumentation

Daily Fix, Deep Fix

Contextualizing with history here is kinda important. As many of the old timers are calling it quits, it may be of benefit to put this down for the next generation of pulp slaying tooth fixers. The story goes like this. There was an observation that failing endodontics was associated with poorly root filled teeth. The following Schilder inference follows, namely: “Inadequate obturation of the root canal invites failure.” So the focus laser beamed on the fill and it’s associated process centered outcome. In order to employ the warm gutta percha technique, the root canal must be shaped so that a continuously tapering funnel is created with its narrowest diameter at the periodontal ligament and its widest diameter at the coronal opening or access cavity.

Back then they were doing this shaping by hand with reamers. And they had these stainless heat pluggers that looked like a spreader that they heated to a “cherry” red before “sheparding’ the gutta percha into the canals with graded stainless pluggers. So in order to get the pluggers to fit, they had to shape the canal to fit the graded pluggers. “Whala”, the continuous taper was unleashed and the rotary revolution followed suit. “Deep shape” became a thing and a lot of root dentin went down the drain. Observationally, we saw some of these break and wondered if maybe all that shape was necessary. Not to mention the strip perf’s. The first to make a change was Buchannan with GT files which at least had a maximum flute diameter. SSW under the direction of Khademi made the biggest leap a decade ago with variable taper instruments. That made things soooo much easier.

Out went shaping, deep shape and in came dentin conservation. Because, well, did you ever find anything that got stronger by whittling on it? Me neither. And yet we still had length control and root filling to contend with and accomplish. That led to the idea of rootform appropriate instrumentation. The balance of not hogging the tooth, and still accomplishing what was necessary. The apical taper kept the fillings from going long and the variable taper kept from too much coronal hogging. Using imaging and knowledge of root anatomy to guide the instrumentation was central to this approach. Using a thoughtful approach to balancing necessary and sufficient notions of root dentin removal achieve the desired process centered outcomes of the operator is the grounding principle behind root-form appropriate instrumentation., Generally speaking as long as the teeth were of average length and didn’t have extreme curves the following could be somewhat prescriptive as long as the prior principle is kept in the forefront of one’s mind and the driver doesn’t fall asleep at the wheel.

So prescription wise there are a number of great instruments out there. What I kinda landed on were three different instruments of different tips and tapers. Namely 17.04V (grey) , 20.06V (yellow), and 20.07V (blue) the V standing for variable taper as none of these are continuous taper instruments. The 17.04 and 20.06 I use are heat treated SSWhite instruments the 20.7 is the F1 by Tulsa which can be obtained in heat treated as well in their gold line. There are lots of F1 substitutes out there if your not a Tulsa fan. The colors here refer to the final file used. Longer roots than the average will typically mean dropping back a size.

This was all a decade ago, before tech. What’s necessary for tech? Probably less; hopefully less, maybe even none one day. There’s some evidence that the move to lose some weight from the continuous taper days has had some benefit in outcomes at longer time frames ie less breaking failures. Are there diminishing returns for losing additional weight, and whittling even less? Harder to tell. Maybe. Harder to root fill? Definitely. The instrumentation appears to approach some conservative silver point preps from the age before rubber or even smaller, considerably smaller with tech ended instrumentation.

The left image is presented with permission from a Shilder trained endodontist. The right was what I was trying to accomplish at the time highlighting root-form appropriate instrumentation as a pillar of Restoratively Driven Endodontics a decade ago. There are still tons of continuous taper rotary systems being employed today, pleasing the dopamine release centers of those enamored with “the look”. Countering those emotions are our own visceral response when we see extraction pending teeth that were given the deep shape death sentence.

Precision Endodontics

Deep Fix

Precision endodontics was a concept John and I were planning to explore in more depth in the text Advanced CBCT for Endodontics: Technical Considerations, Perception, and Decision-Making (Khademi). Like many other noble concepts John wanted to bring to light in that work, the topic was edited bringing the focus back to CBCT by the editor. Still I think the topic is well worth exploring especially in terms of treatment planning and prognostication in endodontics. Wikipedia defines precision medicine as “a medical model that proposes the customization of healthcare with medical decisions, treatments, practices, or products being tailored to the individual patient.” It follows that precision endodontics is a dental model that proposes the customization of healthcare with endodontic decisions, treatments, practices, or products being tailored to the individual patient. In this model, diagnostic testing is often employed for selecting appropriate and optimal therapies based on the context of a patient’s  endodontic condition.

The context of precision endodontics is wide ranging as are the management strategies clinicians chose to prescribe and execute. Generally speaking in endodontic management, decisions are based on which teeth or roots of teeth are to be managed, and how they are to be managed.

In this case, precision endodontics refers to both which, and how the patient was managed. This patient presented with pain and swelling associated with this anterior bridge abutment. CBCT imaging suggested an apical finding limited to the mesial root only. Early in my career, I would retreat the entire tooth. In some instances we would see radiographic clearing of the problematic root only to see radiographic findings and develop on another root that previously presented without findings leading to symptoms. Sort of along the lines of if it ain’t broke, you can’t fix it. CBCT appears to give us better indications of what is “broke” and what isn’t. In this case, in determining whether to retreat the distal root we appreciated the screw post and the bridge that the core supported and realized there were significant associated risks with retreatment and little potential benefit. In this way, imaging diagnostics helped us tailor which tooth and which roots were to be managed. To this extent, we were able to address precision endodontics and further explored the idea as it pertains to interim CBCT’s and management of maxillary molars.

The concept of how to tailor care for patients based on similar case types has been around for a long time with it’s inception stemming from the observations about outcome failure. Humans are pattern generating machines by nature and as such clinicians categorize patients and their conditions and then assign probabilities of the success of their management strategies based on followups. Say for example a clinician has a patient who has significant swelling or drainage from a tooth. Perhaps the clinician, with experience, notes that if endodontic management of that patient type is performed in a single visit there may be an increase in complications, failure to resolve the condition, or subsequent failure to meet patient disease centered or patient centered outcomes. Alternative strategies including management with an interim medication such as calcium hydroxide with temporization is employed and perhaps an increased predictability is observed. Both the duration of time during which the medication is utilized and the frequency with which it is applied can be customized to the perceived needs of the patient. The idea of providing as little or as much therapy as deemed necessary has been referred to as a “titrated treatment”. Managing the case with as many or as few appointments as necessary has been referred to as an “N step” treatment. Both concepts are related to customizing treatment based on the need for varying degrees of time and or type medicament to achieve a favorable outcome.

Many cases are straightforward such as a tooth with caries to the pulp and can be predictably managed in a single visit. For many clinicians, resolution of symptoms offers a degress of predictability, and many teeth are amenable to 2 visit endodontics. However, there are degrees of case types that present as a problem in that they aren’t as predictable with single or even two visit endodontic management. These are loosely referred to as problem case types. For those problem case types in addition to resolution of symptoms we may value clinical features such as resolution of sinus tracts, resolution of deep probing depths, resolution of intraradicular drainage, decreased mobility, and radiographic clearing. Certainly the number of problem cases one may encounter is a function of both the spectrum of patients that are referred, as well as the inclination to evaluate outcomes at different time intervals. The conclusions are no doubt subject to confirmation bias among other cognitive problems that murky the waters of outcomes and thus endodontic decision making.

In this case, we employed calcium hydroxide medication over the course of 3-4 months. We waited for resolution of symptoms as well as the cessation of intraradicular drainage. Additionally, signs of radiographic clearing are evident at the obturation apppointment.

The concept of precision endodontics is important in both navigating a more current retreatment algorithm as well a comprehensive approach to endodontic treatment planning.

Parfocus in Endodontics

Deep Fix
Suffolk Endodontist

Simply put, parfocus in endodontics is where the object of interest is in focus for the endodontist, the scopeside assistant, and the camera. The lack of parfocus can lead to team incohesiveness, lack of efficiency, headaches, and poor documentation. I’ve seen a number of methods for parfocaling. This is mine; it’s worked for me when many other methods haven’t. There are two distinct parts of parfocaling the scope: parfocaling the rig and parfocaling the case.

Parfocaling the Rig

Step 1. Make sure all the components of the microscope are tight . With a fully loaded rig, there are many parts including spacers, beamsplitters, dual iris, and binoculars. You want to make sure each of these are completely aligned, seated, and tight. You may need an allen wrench or screwdriver depending on your setup.

Hampton Roads Endodontist

Step 2. Using either your dental chair, desk, or sliding backwall worksurface create a horizontal worksurface and place some fine print on it. Bring the scope around so that you can comfortably look into the scope and view the fine print under the microscope. Adjust the binocular inclination and interpupillary distance so that your comfortable and you see one circular image surrounded by a singular clear black ring. Set both of the oculars to zero (+/-). Bring the image into decent focus at first second to highest mag, then highest mag. It does not need to be in perfect focus at this point. Now, lock down all 6 knobs on the rig such that it can’t move at all in any plane.

Step 3. If you have a dual iris, open it all the way. If your camera adaptor has an iris, make sure it’s open all the way. Take a picture of a single letter of the fine print. Pull the captured image up to full size on your best monitor in the operatory. Then adjust the fine focus. And take another picture. It will be either better or worse just like at the optometrist. If it’s better, keep going in that direction. Worse, reverse it. Keep playing better or worse using the images on the monitor until you get perfect images. The body of the microscope and your camera are now parfocaled. Trouble at this stage means there is likely something not set up correctly in the microscope setup downstream of the beamsplitter.

Newport News Endodontist
Suffolk Endodontist
Once in focus, all lower mags will be in focus. Due to the open iris they will be overexposed.

Step 4. You have a decision to make here. Glasses or no glasses. I wear flat faced glasses for eye protection. But to each their own. If you typically wear glasses, put em on. Using just the right eye adjust the ocular as you look into the scope. Slowly adjust in the plus direction. Like before, if + is better keep going. If not reverse it. Keep going until things start to get worse. If After you finished dialing in the right eye, repeat with the left. Now go to the lowest setting and double check each on their own. If an adjustment needs to be made use the ocular adjustments at the lowest setting. Make note of your new ocular settings. Do it either mentally, or with a wax pencil. You don’t want anything permanent, because as we age things will change.

Step 5. With the rig still locked down, have your scopeside assistant adjust his/her ocular in the same way you just did. Your rig should now be parfocaled.

Parfocaling the Case

After adjusting the scope for comfort for both the endodontist and scopeside assistant, using the patient chair bring the cavosurface of the tooth into focus at first low, then medium, and finally high magnification. With the iris wide open, take a picture. The picture should be clear and in focus albeit over exposed. The case is now parfocaled. Depending on the depth of the chamber, the focus may need to be adjusted, but most of the case should be in focus throughout the rest of the procedure. Before taking pictures, bump the mag to high and fine-focus using your legs underneath the chair.

Resorption Classification for Clinicians

Deep Fix, Resorption

Historically, classifying systems for resorption have been insufficient to adaquitely guide the treating doctor and inform decision making in the clinical management of resorption . Words like inflammatory and replacement as identifiers are less than ideal as all resorption is inflammatory and all resorption involves replacement.  Identifiers using cervical when used to describe ECIR are not really accurate either and are really misleading as the resorption typically stems from the level of the crestal bone. For these reasons, based on more current models, I use a clinical model of classifying resorption, and subsequent management thereof:

Hampton Endodontist, www.endovirginia.com

The initial identifiers are based first on the derived process location- either external or internal. It’s important to note that the identifiers are derived from imaging, most often CBCT imaging.

Internal Resorption is derived from the pulp. The presentation can be with either a vital or necrotic pulp. Additionally, the resorption can be further classified by extent- namely non-perforating, or perforating. Internal Resorption that is perforating may require surgery to adequately manage the case. Often the process involves a vital pulp, however, occasionally, the pulp may be non-vital. From a prevalence perspective, internal resorption is low; its rare. With internal resorption, since the process is pulpally derived, the replaced tissue is radiolucent. There is not a bone deposition component to internal resorption.

Internal resorption with a necrotic pulp:

Suffolk Endodontist

Internal Resorption with Perforation:

Tidewater Endodontist

External resorption refers to the process of tooth structure being removed and replaced from the outside. Additional identifiers depict distinctions based on a mix of location, cause, and extent. External Crestal Resorption is by far the most common type of resorption. It originates at the level of the crestal bone. A mix of soft granulomatous tissue and hard boney tissue invade and replace the tooth. Additional identifiers include scooping or tunneling. Scooping refers to the pattern of extension by which it progresses in a relatively bowled out fashion as if the tooth removal was performed with a small ice cream scoop. Tunneling refers to a thin fingerlike progression, often many of them progressing axially. Finally, the extent of the External Crestal Resorption may be described. Mild refers to external resorption that doesn’t involve the pulpal space. Moderate is likely to involve the pulp space and will require endodontic therapy. Severe resorption is the extent whereby the tooth is usually no longer restorable. The determination of restorability is made via CBCT. One thing to keep in mind when determining the extent of the resorption is the hard tissue component invading the tooth. It’s easy to mistake tooth schema for invading bone or bone schema. Additionally, the pdl is not present in this area making the distinction more difficult. Sometimes, changing the scale of the imaging during viewing can help. that’s because the process of interpreting schemata is itself dependent on scale. For example, we understand that mouth is part of face, and lips are part of mouth, and vermilian border part of lips. Changing the scale helps with understanding features at all levels.

External Crestal Resorption, Moderate Scooping:

Suffolk Endodontist

External Crestal Resorption, Severe, Tunneling:

Tunneling Resorption presents challenges as the osseous tissue embeds itself axially. Aggressive removal weakens the tooth, however, leaving bone behind allows for resorptive progression.

External Apical Resorption:

Chesapeake Endodontist

External Apical Resorption can be a result of orthodontic force, root canal infection, or in some cases, unknown causal relation.

 

 

External Pressure Resorption:

Chesapeake Endodontist

Teeth and expansile growths such as cysts can cause pressure resorption. Depending on the restorability the extent may be mild, moderate, or severe.

External Axial Resorption:

Hampton Roads Endodontics

External Axial Resorption is identifiable by the radiolucent areas adjacent to root structures. Often this is sequela of trauma and accompanied by an infected tooth. This resorption may be arrested by endodontic therapy and medication with calcium hydroxide. The extent of the injury and development of the tooth determines the prognosis. Often injuries to these teeth include avulsion, lateral luxation, intrusion or extrusion. Depending on the extent of External Axial Resorption, External Ankylotic Resorption may follow over time.

 

External Ankylotic Resorption:

Newport Bews Endodontist

External Ankylotic Resorption may follow after External Axial Resorption. The difference is the lack of radiolucent areas adjacent to the root. As with other external resorption where bone deposition is involved, distinguishing between root and bone schemas can be difficult. The appropriate interpretive response is increased uncertainty. In the developing adolescent, when facial development is not complete, the management of External Ankylotic Resorption is decoronation. An alternative might include autotransplantation if there is a knowledgeable and skilled surgeon.

 

 

Rethinking Retreatment

Deep Fix

Suffolk Endodontist

Hampton Roads Endodontist

 

A more traditional approach to retreatment thinking was given to me courtesy of Ken Serota with this first algorithm. The focus of the decision making is on the quality of the root filling. Decision making with such a matrix often results in retreatment without necessarily improving patient centered outcomes. The second algorithm is restorativley driven with the expressed interest in improving patient centered outcomes and meeting treatment planning objectives. The other pillars of restoratively driven endodontics are present as well including conservation of tooth structure, and determination of restorability based on remaining tooth structure.

Restoratively Driven Endodontics

Deep Fix

It isn’t a new term. Restoratively Driven Endodontics that is. It’s not new. I came up with it in 2007/ 2008 during my endodontic residency at Albert Einstein making the term about 10 years old now. I came up with the term to help myself with a congnitive dissonance. That’s the term for that pesky feeling when you hold two ideas at the same time that go counter-current to each other.  The dissonance that I was experiencing was that endodontic therapy was a type of disease control that was distinct from the restorative process. Let me explain. See during the formation of our endodontic specialty, the founding fathers of endodontics thought it necessary (and maybe it was), to distinguish the practice of endodontics from restorative dentistry. In fact they went to great lengths to do so in order to create the specialty. However, some of these processes that would come to be common practice, often ran counter-current to restorative processes as I began to think about them 10 years ago. So, there I was looking at problem, and I needed some language to help myself out of it.

My program director, Fred Barnett is one of the finest educators I’ve ever known, and I have spent more than a ridiculous amount of getting educated. Due to his vision and progressiveness I was lucky enough to have implant courses which I readily soaked up. Additionally, I had a great lecture from my now buddy John Khademi, that centered mainly on “looking at things through the restorative lense.” Which as a restorative dentist practicing before my endo program, came naturally and made decision making easier. Many of the problems associated with implants at the time were associated with misplacement, issues with abutments, and occlusal spacee etc. So, the fix for their problem was that the model of implants needed to be restoratively driven. So, I made the leap, namely that those processes that were necessary and sufficient to rehabilitate compromised teeth with endodontics needing to be seen and guided through the restorative lens. And thus, Restoratively Driven Endodontics was born in my mind.

Here’s the definition as it sits today:

“Restoratively Driven Endodontics is the overarching philosophy that guides clinical decision making and strategic management to maximize the potential for favorable patient centered outcomes in the rehabilitation of compromised teeth. “

I gave the first iteration of Restoratively Driven Endodontics at Albert Einstein in 20011, and then the more updated version in 2012 in Carroll County. It continues to evolve as new evidence presents itself.

Chesapeake EndodontistHarbor View Endodontist

What’s interesting is what’s developed over the last decade. Certainly a great deal.

If Restorativley Driven Endodontics is the overarching philosophy there are some main ideas that act as pillars that support it. Those pillars of Restoratively Driven Endodontics include Conservation of Tooth Structure, Exacting Restorative Methodology, Dental Conditions Management, Hostility Management, and Restorative Treatment Planning. We will tackle these in time, and touch on them with cases as we go along.

As we tackle Restoratively Driven Endodontics the landscape of what we know and how we do it will undoubtedly change. The armamentarium of models guiding our thinking and the technology that guides our processes will hopefully drive better outcomes for our patients. With that in mind it is important that we realize that many concepts are linked. Such that it is hard to understand one area, without having knowledge of another.

Newport News Endodontist

To that end, the efforts of this blog will be to illuminate and elucidate the network of these mutually supporting ideas, concepts, practices, and philosophies in a coherent way.