Is PEIR a causal factor for non-eruption?

Published: January 2017

Bulletin #62, January 2017

Is PEIR a causal factor for non-eruption?

Pre-eruption intracoronal resorption (PEIR) is an uncommon condition or, putting it a different way, it is a condition which is rarely recognized by anyone apart from pediatric dentists. It is still largely confused with caries and it goes by a whole host of names, including “occult” or “hidden” or “pre-eruptive” caries or “pre-eruptive intra-coronal translucencies”. The July 2013 bulletin newsletter on this website1 discusses the subject in some considerable detail and I noted that “….. there is no evidence to assume that pre-eruptive intracoronal resorption has any adverse effect on the normal eruption mechanism and, indeed there are cases in which an effete lesion will only be discovered many months or years after the tooth has erupted ……………….. and be misdiagnosed as caries! Nevertheless, Fate has a curious penchant for accompanying the next patient to sit in my operating chair, exhibiting something that I had said does not occur or does not exist. In this instance, it was a patient with two PEIR-affected, impacted canines, thereby offering contrasting anecdotal evidence that perhaps the lesion was the cause of the non-eruption.

Permit me to relate the story……..

In April 2012, I received an e-mail from the mother of a young boy regarding his impacted canines, although no radiographs accompanied the request. I replied to the e-mail but not further contact was established until 2 years later, when I received a second e-mail to the “Clinical Consultation” feature on my website. The son was now 16 years of age and the family was located on the other side of the world – 10 time zones away from me, here in Jerusalem. Mother had serendipitously come across my website in a search for a solution to her son’s orthodontic problems, specifically to the non-resolution of the impaction of his maxillary and mandibular canines of the right side. Mother (whom we shall call Dr. Marten) is a medically qualified internist and, with this academic and clinical background, she had quickly gained a deep understanding of the biology of tooth movement. She easily finds her way around the internet and runs a website of her own, which is how she came across me. She had read all of the monthly newsletter bulletins on this website and much of the content of my published articles and textbook. Several references that I had made to PEIR had caught her attention.

Her son’s medical history was non-contributory, although he (we shall call him Jeff) is an active youth with a history of an isolated traumatic incident to the right side of his face, when he fell in the bath at home, at the age of 8 years.

62Fig._1a__b 62Fig._1c__d

Fig. 1a-d. Intra-oral views of the teeth from the front, showing alignment and space opening for the impacted canines. A cant in the occlusal planes on the right side in March 2014, is the result of anchorage loss (intrusion), following 2 years of active orthodontic treatment, which included extrusive traction on the 2 canines.

It transpired that Jeff had by now been in orthodontic treatment for 2 years and had already had surgery performed twice on each of these canines and an open bite had developed on the right side (Fig. 1) – a sure sign of anchorage loss caused by the reactive force actually intruding the adjacent anchor teeth. Attachments had been bonded to the exposed teeth during the first round of exposures and extrusive traction had been applied in each instance – all to no avail.


Fig. 2a. Panoramic view of the dentition showing right canine impaction in both arches and delayed eruption of the left mandibular second permanent molar.

Fig. 2b. A panoramic view taken a year later showing full maxillary and mandibular fixed appliances, with space opening and attachment bonding to the impacted canines.

On the radiographs and photographs that Dr. Marten sent me, I discerned the presence of gold chains and steel ligatures exiting the repositioned and healed closed surgical flaps (Fig. 2a, b). Traction had been applied to each tooth, from the full thickness rectangular archwires in both jaws, yet follow-up radiographs taken over the subsequent months showed no apparent progress of the two canines.


Fig. 3. A series of radiographs over a 4 year period showing the PEIR resorption (arrows) of the cusp tip in the maxilla. Note how the bonded eyelet attachment has been placed on the thin undermined enamel surrounding the lesion.


Fig. 4. A parallel series of radiographs to show the similarity of the condition in the mandibular canine and how the eyelet has been similarly placed on the thin undermined enamel surrounding the lesion.

The only abnormality that I could detect on these radiographs was that each of the two canines exhibited a PEIR lesion affecting the tip of its cusp and that this lesion could be seen on the pre-treatment panoramic radiograph that had been taken in 2010, becoming progressively larger on all subsequent films until 2013 (Fig. 3, 4). This was not recorded in the orthodontists’ nor surgeons’ notes, suggesting that they had not noticed it or had not considered it relevant. However, Dr. Marten had noticed it and had even asked about it– hence her interest in what she saw in my website publications and her motivation in contacting me.

When the initial and prolonged attempt at eruption failed in 2012, the orthodontist advised that the canines be extracted – a decision that Dr. Marten refused to accept. She took Jeff for a second opinion and subsequent treatment to another orthodontist and another surgeon elsewhere. She became very dissatisfied at the absence of progress with the canines there, too, and so Dr. Marten contacted me.


Fig. 5. A panoramice view of the dentition taken pre-operatively in 2014, in Jerusalem. The apparent improvement of the location of the canine is likely due to intrusion of the adjacent teeth, rather than actual extrusion.

I questioned whether Jeff’s attendance for treatment had been regular, as directed by the orthodontists and was informed that he had been cooperative throughout. The series of radiographs and photographs referred to above were sent to me and these indicated that the attachments had been properly placed, the bonded gold chain was correctly drawn towards the main archwire and the direction of traction was appropriate in relation to the location of each of the two teeth. I thus concluded that there was every reason to believe that the approach to treatment and its execution had been in line with the best standards of practice. The follow-up radiograph (Fig. 5), taken in early 2014 shows what appears to be some eruptive progress of the mandibular canine, but this encouraging observation is more likely to have been the result of the intrusion of the adjacent anchor teeth, following the long period of fruitless extrusive traction.

What then could be the reason that these two teeth would not respond to orthodontic forces?

To the best of my knowledge PEIR is not a cause of non-eruption of the affected tooth.2 This condition has never been thoroughly investigated with disciplined studies and, while appearing frequently in the literature, the articles relate to prevalence or to single or multiple descriptive case reports highlighting its treatment.3-7 As a general rule, PEIR-affected teeth continue to develop their root apices, quite regardless of the severity of the resorption and they remain vital. Their eruption is not usually delayed and, with their appearance in the mouth, the resorptive lesion loses its nutritive source (apparently the intra-follicular fluid) and the progress of the resorption abruptly ceases.

A glance at the series of radiographs revealed an irregular contour of the maxillary right canine as early as 2010 (Figs. 3, 4). In the later radiographs, obvious destruction of the tips of the crowns of both right cuspids could be clearly seen, with radiolucent dentine immediately behind them. Eventually, the lesions were seen and noted by the orthodontists, but only after 2 years of failed orthodontic treatment and, even then, they were not considered important enough to eliminate and restore.

An expert radiologist was also consulted on the reasons for failure of the case, specifically in regard to PEIR. He saw the cone beam CT and he noted that the maxillary canine showed crown resorption which “….. may correspond to PEIR; however, surgical microtrauma to the dental structure cannot be ruled out as an origin for the crown resorption”. In fairness, he had not been appraised of the fact that the PEIR was present before treatment commenced. However, he added “ …. the biomechanic direction of the forced eruption should be considered as a contributor factor for the slow eruption process” and “…. no suggestive signs of pathology and/or ankyloses were noted.” No mention was made of the PEIR lesion in the mandibular canine and, therefore, presumably it went unnoticed!

It is inconceivable that the PEIR lesions would not have been seen during the two surgical procedures that had been performed to expose each of these two canines and yet they did not attract sufficient attention or perhaps the gravity of their destructive potential was not comprehended sufficiently to warrant treatment. Even assuming that PEIR has no adverse effect on eruptive potential, the fact of the presence of an extensive resorption defect should have been recognized by the surgeon as something that needed treatment at the exposure visit. An open exposure would have arrested the PEIR. 2 A closed procedure would still be a reasonable surgical approach, provided the resorptive lesions were sealed and isolated from the surrounding tissues. This was not done and resuturing the flap had clearly re-established a nutritive source to enable the lesion to return to its destructive path for many more months.

In general, it is understood that right and left canines in the same jaw are developmentally related, but this is not true for canines in opposite jaws. These are not developmentally related. For this reason, I saw it as decidedly odd that the right side maxillary and mandibular canines were the only teeth in the entire dentition which were impacted and that both teeth were afflicted with PEIR. They were also the only teeth that had steadfastly resisted orthodontic force application, despite the fact that the surgery and orthodontic traction seem to me to have been impeccable. This could not possibly be a freak occurrence, when all other teeth had erupted naturally and had subsequently, routinely and predictably been biomechanically re-arranged into normal alignment, by responding to orthodontic forces. Coincidence is out of the question!

In the absence of any other pathological entity, it seems logical, therefore, that suspicion must fall on the PEIR lesions in these teeth as the only obvious factor which remained unexamined and, in the absence of any other likely cause, may indeed have been responsible for the failure of the teeth to erupt. It is also open to speculation that the cause of the PEIR was the trauma inflicted on the right side of his face at age 8 years. Nevertheless and whatever the cause, the fact was that only the right side maxillary and mandibular canines had developed PEIR and both had resisted all attempts to erupt them.

It was on this line of argument that an empirical working diagnosis was determined, namely that the PEIR was responsible for the resistance of the teeth to respond to the extrusive traction forces. Accordingly, I quoted the July 2013 bulletin on my website in the e-mail in which I replied to Dr. Marten, as follows:-

“…..Comparisons of radiographs taken by different methods - panoramic compared with periapical views and even periapical views compared with other periapical views - is notoriously misleading, since the angle of the x-ray cone is not usually standardized and movement of the teeth may well be more virtual than actual. From the series of views that you have sent me, I see little or no movement in either tooth.

As far as my July 2013 bulletin is concerned, I do believe that both canines have undergone pre-eruptive intracoronal resorption and it is entirely possible that this was due to the 2006 trauma. As I wrote in the bulletin, it is generally believed (but not certain) that the resorptive initiation is through an enamel defect in the crown formation which, when it occurs (which is rarely), it is likely to affect the tips of the crowns of permanent canines - as we see here and as I illustrated in the bulletin. Having noted that, does PEIR stop eruption? Apparently not, at least not in my limited experience. Furthermore, having surgically exposed the tooth, the lifeline of the lesion will have been interrupted. However, re-closing off the surgical wound completely, without at least filling the resorbed area, will then likely re-ignite the resorption process. This means that the resorption process may still be eating away at the inside of the crown of the tooth. Nevertheless, it is unlikely to affect the dental pulp - as explained in the bulletin.

From the orthodontic point of view, space has been provided adequately for both teeth and traction has clearly been applied with little complexity. Furthermore, the direction of traction appears to have been correct.

So, in the absence of any other explanation why the teeth have not moved, I have to go with the idea that pre-eruptive intracoronal resorption may indeed prevent movement, in some instances. That being the case, we now have to look at the latest renewed exposure adventure a little differently. I use the word adventure, because the entire raison d’etre or modus vivendi of the advice here is based on this questionable assumption …..etc. etc


Fig. 6a. A wide surgical flap has been raised and the resorption crater of the maxillary resorptive lesion (arrow). The original bonded eyelet detached during the procedure and a new one was bonded in its place.

Fig. 6b. The closed exposure flap has been resutured and only twisted and hooked steel ligature from the eyelet is visible. An elastic chain was placed under minimal tension on the two brackets of the 2 adjacent teeth.

Fig. 6c. The middle of the elastic chain is raised with a tweezer and loaded on to the hook, to provide a light and measurable continuous extrusive force to the canine.

In her reply to me, Dr. Marten asked that I write my detailed surgical operative recommendations in a letter to the latest and very senior orthodontist with whom she was now in contact, together with recommendations to the surgeon with whom he would work. My advice to the surgeon, therefore, was as follows:-

“…..1. expose the two canines (Fig. 6a), check the adequacy of the bond and remove any adhesions of tissue (possibly scar tissue) from the crowns of the teeth, but not to extend the exposure into the CEJ indent listindent marginarea.

2. identify and superficially clean the mush from the resorbed area of the crown - but not to extend the cavity excavation deeper. Most important: absolutely to leave the deeper area of mush untouched, for fear of exposing the vital pulp. Restore the crown with composite material, to seal off the cavity from the surrounding tissues. While I have no problem with the surgeon checking for mobility of the tooth at this stage, I would argue strongly against his/her pushing elevators down the PDL along the root surface, since this will almost certainly cause an ankylosis, if not already present (there are no signs at present).

3. re-suture the full flap back into place (Fig. 6 & 7). As the orthodontist, I would want to be present at the surgery, to apply immediate traction to both teeth simultaneously, as before, and directing the patient in using vertical intermaxillary elastics to support the anchorage and, thereby, avoid intrusion of adjacent teeth.

4. Depending on the method of traction and its power range will depend how frequently Jeff should be seen, which is a decision for the orthodontist.

5. I would expect to see positive results within 3-4 months (Fig. 8). If nothing happens, then the teeth should be which case, I would like you to have them photographed and sent to me (please!) - or, better still, place them in formalin and send them to me for further examination. If they do move, please tell me. It may help someone else, since I will have learned something new!”


Fig 7. A view of the right side of the mouth showing the two similar extrusion mechanisms.

The senior orthodontist contacted several surgeons, none of whom accepted this approach nor the reasoning behind it and they all declined to treat Jeff.

At this point and frustrated at not being able to obtain the treatment recommended, Dr. Marten decided to have the surgery performed here, in Israel. I advised her that she and Jeff would need to stay within easy access of Jerusalem for an approximately 4-week period, during which they would spend a 24 hour period in hospital and 2-4 short visits to my orthodontic office.

The short and concentrated visit took place in March 2014, when the teeth were re-exposed by the then head of the Department of Oral and Maxillofacial Surgery , Professor Refael Zeltzer. He identified the PEIR lesions in each tooth and, while he maintained hemostasis, I carefully excavated the resorption mush superficially and filled the freshened cavity with glass ionomer cement, leaving the deeper (sterile) debris enclosed. I re-applied active traction to each tooth before the patient was awakened and transferred to the recovery room.

Jeff and family remained in Israel for only 3 weeks, continuing his orthodontic treatment when he returned home. The mandibular canine finally erupted into the mouth about 6 months later (Fig. 8).


Fig. 8. Views from the buccal and lingual aspects of the right side of the jaw, following resolution of the mandibular canine. The maxillary canine is seen here after the failed apicotomy procedure.

In contrast, the maxillary canine still refused to budge! Where should we look for answers? Why did this tooth fail to respond?

One possible clue is that during the surgery we found the resorptive lesion to have become more extensive than expected and access was restricted, particularly on the palatal side. Accordingly, it is possible that the restoration that I placed was not as sealed and impermeable as I had hoped for, which may have permitted the resorption process to re-generate.

Another potential cause dates back to the first two surgical episodes. In an answer to a question from the first orthodontist, the surgeon at the time wrote in the surgery notes “….. once I expose the crown, I do give it a slight “nudge” with the curette to check mobility…….. there was no apparent sign of ankylosis.” I have stated elsewhere8 that, when the orthodontist is not present at the exposure of an unerupted tooth, the surgeon will tend to err on the side of more radical bone and soft tissue removal and will extend the exposure more widely, to prevent the tissues from healing over. The surgeon may even loosen up the tooth with an elevator pushed down the PDL beyond the CEJ, to assist the orthodontist in the resolution of the impaction.

In the present case, the orthodontist considered that the maxillary canine had a hooked root apex and that perhaps this was the reason for failure. As I have pointed out in relation to dilacerated central incisors and to hook-ended roots in general, distorted root shape is generally the result of an extraneous factor that is not permitting the tooth to erupt, thereby reducing the height of alveolar bone available for the development of a normal root. The root then develops in a restricted space, bound by the lower border of the mandible, the maxillary sinus, the floor of the nose, periosteum elsewhere or the inferior alveolar nerve. Elimination of the extraneous factor will permit the tooth to respond to eruptive forces, natural or applied.

Notwithstanding, Jeff was referred to another surgeon, who performed an apicotomy. This is a procedure in which the hooked apex of a maxillary canine is tooth is amputated, without adjunctive root canal treatment. Apicotomy is not a well known procedure, but is claimed to offer a good chance of success in suitable cases.9 To the best of my knowledge, the efficacy of the method has never been properly tested and its appearance in the literature is represented only in the form of case reports and descriptions of the technique. For young Jeff Marten the method failed to move the tooth.

I know of no published journal articles which describe PEIR as an etiologic or associated feature of tooth impaction and the evidence, such as it is, indicates that the affected teeth erupt naturally. Nevertheless, from the entirely anecdotal evidence that is offered in this single case report, it seems that PEIR should be considered as an unlikely but possible etiologic factor in disturbance of the eruption mechanism of a tooth.

It has been my specific purpose to bring a possible relationship between PEIR and non-eruption to your attention, by publishing it on this website.


1. Bulletin #23 July 2013. Pre-eruptive intracoronal resorption

2. Becker A, Chaushu S. Impacted teeth and the 6 incarnations of resorption. (Les six formes de résorption associées à l’inclusion dentaire). L’Orthodontie Francaise 2015;86:277–286.

3. Davidovich E, Kreiner B, Peretz B. Treatment of Severe Pre-eruptive Intracoronal Resorption of a Permanent Second Molar. Pediatric Dentistry 2005;27:1

4. Seow WK. Pre-eruptive intracoronal resorption as an entity of occult caries. Pediatric Dentistry 2000;22:370-375.

5. Holan G, Eidelman E, Mass E. Pre-eruptive coronal resorption of permanent teeth: Report of three cases and their treatments. Pediatric Dentistry 1994;16:373-377

6. Seow WK, Lu PC, MacAllan LH. Prevalence of pre-eruptive intracoronal dentin defects from panoramic radiographs. Pediatric Dentistry 1999;21:332-339.

7. Kupietzky A. Treatment of preeruptive intracoronal radiolucency. Pediatric Dentistry 1999;21:369-372.

8. Becker A, Chaushu S. A chapter entitled: Surgical treatment of impacted canines: what the orthodontist would like the surgeon to know. Editor Michael Kleiman, in: Oral and Maxillofacial Surgery Clinics of North America. New York: Elsevier Inc. 2015;27:449-458.

9. Puricelli E. Apicotomy: a root apical fracture for surgical treatment of impacted upper canines. Head Face Med. 2007;3:33. DOI: 10.1186/1746-160X-3-33