Dear Thejokrishna:

Few months ago, I read a review at International Endodontics Journal conducted by a group of New Zealand. They exposed that with the electronic apex locators, assessment of working length has become more predictable and may prevent unintentional over-instrumentation. But EALs can affected by multiple factors like the diameter of the apical foramen, the apical constriction and the size of file used and other that I can´t remember clearly. Interesting topic.

thanks, Dr Cristina Benavides

Hi,

yes, interesting topic.

Is there any information about the type of teeth they used in that study?

Front teeth? Lateral teeth? Already resorbed or not yet?

Background:

I do transplantations of primary canines (in case of loss of upper incisors due to trauma).

The resorption of primary canines is very asymmetric: While the labial aspect of the roots may be still have original root length the lingual aspect may be nearly completely resorbed, thus revealing a steep oblique, mostly curved, concave outline of the lingual aspect of the root.

Thus, if a rct is done, the "apical foramen" (as defined by the most apical borderline which the instruments reached) changes its vertical position: at the lingual aspect it moves in the coronal direction. Widening of the rc increases this effect. The buccal

This reveals some questions:

1. How can we define the apical foramen, resp. the working length? Shall the palatal or labial aspect be used as reference landmark? Is a 3D-radiograph needed?

2. How is such a situation considered in the measuring devices? Do they use the palatal or labial value?

3. Is this a problem of just the primary canines? Whats about the situation of primary incisors, molars? Are there differences between upper and lower jaw?

Hello,

since ur doing transplantation, you can do the root canal first or outside the mouth and then transplant.

Good afternoon from Spain

Determination of working length for teeth with wide or immature apices: a review. Kim YJ, Chandler NP.

This is the paper I referred, but it´s a review.

This review examines multiple articles. In one, (Clinical evaluation of the measuring accuracy of ROOT ZX in primary teeth. Kielbassa AM, Muller U, Munz I, Monting JS.) they use all type of tooth and statistical analysis didn`t show any influence of the type of tooth (34 molars, 37 incisors) on the results of the EALs measurements. Also no differences between resorbed and nonresorbed roots could be evaluated. Others articles included in the review are with primary molars with and without resorption, but was in agreement and concluded that the EAls had high accuracy irrespective of presence or absence of root resorption.

Also, the review include laboratory studies that compared the ability of conventional and digital radiography and EALs in determining working lengths in primary teeth with or without resorption, with varied results.

Regarding your questions, I´m not an expert in this topic, but you can access and remove pulp tissue and determine with the electronic apex locator the root canal lenght, then extract primary canine and determinate the “real” length. With this data you can determinate the EALs' error and without radiography.

Interesting topic. Have a good day.

Dear Shashirekha Govind,

thank you for your hint. That is what we do: extraoral endo. You may want to read our papers on that presenting a fast and reliable method for endo treatment plus allowing the elongation of the transplants, if necessary: Insertion of titanium posts from a retrograde direction...

You seem to do such a treatment as well? I would like to get some more information about your experiences...

My comment was not intended to explain our method for transplanting teeth, but to offer my knowledge from these treatments (and which most probably not many dentists have) to help colleagues who want to do any orthograde endo.

Dear Cristina Benavides,

thanks a lot for your information. Will have a close look to the mentioned article.

Yes, following your proposals could clear the issue. Unfortunately - you could not know that - I can't use my transplants because I want to have a non-injured crown: this seems to be a decisive factor that we haven't seen any fracture in our teeth which we replanted or transplanted and in which we did our endo treatment with the posts from a retrograde direction. The integrity of the crown is (most probably) decisive. Another issue: A crown without any filling cannot lose its coronal seal... Thus, I can't measure the root length by the device.

Good reason and excellent approach.

Thanks for share it.

When you do transplantations of primary canines, do you soak the tooth in sodium fluoride or products such as emdogain?

Hi, Christina,

thank you for your question.

The answer is for both substances: No.

Fluoride would not be good for the cells which we need in best circumstances for the (re-)establishment of a functional PDL. (We call it functional, since it functions as a PDL should function, that means anchoring the tooth by fibres, not hindering the alveolar growth, ...; I don't like the expression 'normal', because after a severe damage it would be 'normal' that the PDL does not (re-)gain the typical properties but would show ankylosis instead...)

No, we don't use Emdogain; we did many years ago but did not find this would be necessary; also without Emdogain the teeth healed in with a functional PDL predictively.... We are not yet clear whether we should use topical glucocorticoids and/or tetracyclines. They are relatively cheap (compared to Emdogain), and thus...

I learned that fluoroapatite is more resistant to ankylosis than hydroxyapatite and shown to reduce significantly the risk of resorption. And this was the cause whereby a tooth that has been avulsed for greater than 60 minutes with dry storage were soak in fluoride. But the remaining PDL should be removed previously so I supposed you would not use this.

However with emdogain, I expected better results. So thanks for this information, it´s so useful (emdogain price is considerable).

One more question (I'm sorry to be annoying): do you splint it?

Thanks a lot Yango, I'm learning a lot.

Hi, Christina,

you are right, in teeth with a dead PDL: take the PDL off, and apply flouride.

But: in transplants we expect to not have a dead PDL; if that would be the case, I would never transplant in growing patients; this would cause severe infrapositions; in contrast, ankylosed teeth are the indication for transplants: take out the tooth with a non-functional (=dead) PDL and replace it by a tooth with such a functional PDL... allowing growth of the alveolar process again...

Emdogain needs viable specialized cells, it can help these in regenerating, in attaching, in migrating. But it can't produce new specialized cells from precursor cells, at least not in sufficient numbers.... All PDL cells dead? Emdogain can't help getting new ones...

In our studies we observed exactly that. Thus, for avulsed teeth it is crucial to rescue them immediately in best circumstances, to loose as few cells as possible. Therefore we equip every school here in Germany, in Austria and Switzerland with tooth rescue boxes, which contain a complete cell culture medium (shelf life at room temp: 3years (!)). And in statistics it was this immediate rescue which allowed the maintenance of an unknown high number of teeth, outreaching every other study in the field significantly.. The emdogain (plus corticoids & tetracyclin) had a positive effect, but only in cases which were not hopeless (PDL dead) but also not rescued optimally. And not predictably, you get a 50:50 chance, but we take it... We can't replace the rescue by treatment, not yet....

Thanks Dr. Yango Pohl

Hi, Christina, and all

Yango would be ok.... if you don't mind. At least, don't use the "Dr." when addressing me...

Dear friends,

This is an interesting topic, and I would like to share with you this article I have published in IEJ this month. Hopefully, it will answer your question!.

Best regards,

HMA Ahmed.

Article Anatomical challenges, electronic working length determinati...