Radiolucencies

For a dental professional who looks at dental radiographs frequently, coming face to face with a radiolucent lesion in the alveolar bone of our patients is an extremely common occurrence. Most often, these lesions are associated with teeth that are in need of endodontic treatment.  In fact, according to a recent article in the Journal of Endodontics,* over 90% of radiolucent lesions associated with teeth are either a cyst, apical granuloma, or an abscess.  Sometimes these lesions are affectionately referred to as LEOs (Lesions of Endodontic Origin). 

While it is clear that most radiolucent jaw lesions are LEOs, the literature is anything but clear on the distribution of the various types.  For example, different studies have reported the incidence of cysts to be anywhere from 6% to 55% and that of granulomas to be anywhere from 46% to 94%.  Such wide ranges make it difficult to predict with any accuracy the exact nature of a radiolucent lesion.  However, does it really matter whether the lesion in question is a cyst, granuloma or abscess?  Historically, this question may have been more pressing because most experts believed that surgical enucleation of cysts was necessary in addition to non-surgical root canal treatment, whereas teeth with associated granulomas could be effectively treated with root canal treatment alone.  

However, recent data suggest that even some cysts can resolve with proper non-surgical root canal treatment utilizing stringent infection control.* But what should be done when the lesion doesn’t heal (i.e. the lesion is still present radiographically with or without accompanying symptoms)?  A non-healing lesion should be followed closely to assure no changes take place over time.  If the lesion remains unchanged and the tooth remains asymptomatic, close follow-up without additional treatment may be justified.    However, it is also important to bear in mind that while they are the most common, LEOs are only one entity in a long list of entities that can cause radiolucent lesions in the jaws.   The aforementioned article in the Journal of Endodontics describes a study which utilized data from the Department of Oral Pathology at the University of Minnesota School of Dentistry. The data in this study came from biopsy samples that were analyzed over a period of 15 years representing a total of 9,723 radiolucent lesions in the jaws.  Lesions that were on the ramus or angle of the mandible were excluded.  

The researchers found a wide variety of diagnoses associated with these lesions.  In fact, 30 distinct entities were identified.In the final analysis, 73% of the biopsy samples analyzed were diagnosed as either a cyst or granuloma.  While this seems to contradict the statement made earlier that over 90% of radiolucencies are LEOs, it is important to remember that these samples were from mostly non-healing lesions.  This would result in fewer LEOs because many LEOs resolve following root canal treatment.                       

So what type of lesions made up the other 27% of biopsy samples?  Keratocystic odontogenic tumors (KOT, formerly known as odondogenic keratocyst or OKC) were the most common, making up 8.8% of the samples. Other lesions occurring in the 1-2% range included Central Giant Cell Lesions (CGCL), ameloblastomas and cemento-osseous dysplasia.  Metastatic lesions were identified in less than  1% of the samples.  As mentioned above, many other types of lesions were identified but most at less than 1%.  In summary, it is important to remember that most radiolucent lesions associated with teeth are of endodontic origin.  

However, many other entities exist and must be considered in the differential diagnosis.  Sensibility testing (percussion, palpation, thermal testing) should be performed on all teeth with associated radiolucent lesions.  An abnormal relationship between pulpal diagnosis and radiographic appearance may help identify an entity as not of endodontic origin (e.g. a vital tooth with a large radiolucency).  Non-healing lesions or lesions which don’t seem consistent with pulpal diagnosis should be followed closely and considered for biopsy.     

*Frequency and Distribution of Radiolucent Jaw Lesions: A Retrospective Analysis of 9,723 Cases.  Journal of Endodontics, Volume 38, Issue 6, Pages 729-732, June 2012.

Root End Surgery

Though it pains us to admit it, we here at Mountain View Endodontics have to concede that Root Canal Treatment is not always 100% successful. While it is difficult to quantify success rates due to significant variations in how “success” is defined, multiple studies over various decades have established that well-performed non-surgical root canal therapy is highly successful. With regard to the small minority of cases that do not achieve long term success, the causes of failure are many and varied. Some causes such as inadequate length or density of the obturation (often indicative of inadequate chemo-mechanical debridement), contamination during treatment due to improper isolation, or crown-down leakage can be effectively addressed via endodontic re-treatment followed by placement of a new, high-quality coronal restoration. 

Certain other causes of failure, or for certain restorative reasons, endodontic microsurgery may be a better choice.Historically, endodontic surgery (aka root end surgery, apicoectomy) has not had success rates comparable to traditional non-surgical root canal therapy. However, in the last decade or so, advances in equipment and technique have resulted in excellent success. The Fall 2010 Edition of the Colleagues for Excellence newsletter (www.aae.org/colleagues) addresses this topic and lists some of the enhancements that have led to increased success rates. Principal among these are the use of the dental operating microscope to identify previously unidentified and untreated canals, fins or isthmuses, the use of specially designed ultrasonic tips that permit accurate and well-centered retro-preps, and advanced bio-ceramic materials such as Mineral Tri-oxide Aggregate (MTA) that provide an excellent and biocompatible root-end seal. The result of these improvements is that endodontic microsurgery, with proper case selection and technique, results in success rates reported in the mid-to- high nineties whereas traditional root-end surgery resulted in success rates closer to 50%. 

The following report illustrates a clinical scenario in which apical surgery was indicated: The patient reported to the general dentist for new crowns on #’s 8 and 9.

The all-porcelain crowns were over-contoured and were in supra-occlusion.  The crown on #9 split vertically and the pieces were re-cemented by the general dentist.  The teeth had been previously treated endodontically, and upon clinical testing, both had palpation and percussion tenderness. The pre-op radiograph revealed that both teeth had fiber posts and root filling material that had been extruded beyond the apex.

An initial attempt was made to treat the case non-surgically. The fiber posts were removed from both teeth as well as the obturation material in #8 via non-surgical root canal re-treatment.  However, attempts to remove the extruded gutta percha from #9 from an orthograde (through the coronal access) approach were unsuccessful.

Via apical surgery, the extruded material on #9 was removed, both root ends were resected and the roots were sealed apically with bioceramic material.

The patient had minimal post-op pain following the procedure and the natural dentition has been retained thereby avoiding the well-known challenges of implants in the esthetic zone.

#8 following restoration with a new fiber post, core and crown

#9 following restoration