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08 April 2020

Endodontic retreatments: Interview with Prof. Shimon Friedman

Massimo Gagliani

Several milestone papers have been written in the last years on Endodontic Retreatments and some of the most important among them have been authored by Prof. Shimon Friedman, University of Toronto.

Prof. Friedman has been a worldwide recognized authority in this field for over thirty years.
For this simple reason Dentistry33, with Prof. Massimo Mario Gagliani, decided to ask Prof. Friedman some questions about this fundamental topic in everyday dentistry, not only for the Specialists but also for the General Practitioners.  

M.G.: Does Retreatment of root-filled teeth with endodontic disease still offer value to patients, or are these teeth increasingly replaced by implants? 
S.F.: This is an important question and a contemporary dilemma. Many respected authorities have argued in favour of replacing root-filled, diseased teeth with implants. The main argument supporting this approach is that the long-term prognosis of these teeth, if managed by orthograde retreatment or apical microsurgery, is compromised compared to the expected longevity of implant-supported crowns.   In my view, this approach is flawed because it prescribes interventions with disregard to the fundamental principles of case selection, that highlight the patient’s attributes and informed preferences, the specific site including the tooth, supporting bone and periodontal tissues, a detailed analysis of benefits and risks associated with all available treatment options, cost and the clinician’s expertise. In my experience, when patients are properly informed on all of the above, most of them opt to retain the teeth by means of retreatment or apical microsurgery. Thus, Retreatment has great value and is an indispensable treatment modality for all those patients who may consider it the best modality for their own root-filled teeth with endodontic disease. It also is important to note that indiscriminate replacement of teeth with implants has been questioned by noted authorities; for example, Prof. Jan Lindhe stated in a 2014 interview with the British Dental Journal that: “Many dentists find it easier to remove a tooth and place an implant than to use the data in the literature to treat the tooth for its conditions. Maybe there is an overuse of implants … and an underuse of teeth as targets for treatment.” As well, it would appear that some dentists nowadays take a step back from routine replacement of teeth with implants, in response to emerging knowledge on the long-term behaviour of implants and implant-supported crowns.      

M.G.: Will apical microsurgery become pore popular in treatment of root-filled teeth with endodontic disease?  
S.F.: The surgical approach to treatment of root-filled teeth presenting with endodontic disease has always been popular, more so in some countries than others. For example, a survey among USA endodontists published in the early 1990’s reported their primary preference for surgical management over orthograde retreatment for root-filled teeth with posts. Nevertheless, in the past two decades there have been many technological advances introduced to the surgical procedure that result both in reduction of risks and improved healing outcomes. Consequently, analysis of benefits and risks associated with retreatment and surgery is more often shifted in favour of the latter, compared to the past. Among these technological advances is Cone-beam CT imaging, that allows better mapping of the surgical site and planning of the approach. As well, it enables the manufacture of 3-dimensional guides that facilitate access. Other important technologies include dental microscopes that enhance precision of root-end management, ultrasonically-energized tips that enable the preparation of deeper and better aligned root-end cavities, and novel root-end filling materials that form a well-sealing barrier but also allow growth of cementum over the root tip to provide additional, biological barrier. As a result of all of the above, more clinicians now perform apical microsurgery than ever before and, overall, the quality of their surgical procedures is improved compared to the past.  

M.G.: Bacteria in endodontic disease – which is the state of the art on disinfection protocols?  
S.F.: Root canal disinfection has been a major focus of technological innovations in endodontics in the last two decades. While novel irrigation, medication and root-filling materials have been introduced that claim improved antibacterial activity, the main emphasis has been on enhancing irrigation by ultrasonic, sonic or laser energy, used either for agitation or activation of irrigation solutions. Many research publications have reported varying efficacies of all of the above, mainly in-vitro and occasionally in-vivo, but none have yet shown improved healing outcomes compared to the conventional method of irrigation with a syringe and fine-size needle. Thus, the state-of-the-art still remains syringe-needle irrigation, with many clinicians hoping to enhance disinfection by the use of the above technologies.   That said, the efforts to improve root canal disinfection have, in the past two years, been taken to a higher level by the introduction of the innovative GentleWave technology. Although the research and adoption of this technology are still in early stages, emerging data may be interpreted as suggesting improved healing dynamics or, possibly, improved healing outcomes.  

M.G.: Will CAD/CAM devices provide better restorative solutions for root-filled teeth?  
S.F.: Like most of the endodontists in North America, I am not very well informed on the emerging use of CAD/CAM restorations for root-filled teeth. Intuitively, this approach appears to be advantageous because it conserves tooth structure, compared to the conventional restoration with full-coverage crowns. It also appears to streamline the restorative procedure compared to the manufacture of posts, core buildups and crowns or onlays. Nevertheless, the research I have seen on CAD/CAM restorations has raised specific concerns regarding fracture and debonding. These concerns and others will have to be explored in longer-term outcome studies before emphatic arguments can be made for or against the adoption of CAD/CAM restorations as the preferred approach for root-filled teeth.       

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