VinceLombardi once eloquently stated that “practice is not perfect, only perfect practice makes perfect”. In other words, in the clinical setting, we are able to repeat a particular treatment over and over again, but may not achieve the desired outcome of success. In order to provide the most predictable treatment plan to our patients, we must continue to learn and progress in all disciplines of dentistry in order to have clinical success, and from the physician’s standpoint, the greatest variable in medicine is the human being himself. The criteria for evaluating the effectiveness of root canal treatment are inevitably interrelated with important changes in the equipment we use clinically.
From the day the first endodontic treatment was performed, the aim of endodontic treatment was constant, namely the prevention and treatment of periapical inflammation, the final result of endodontic treatment was the complete healing of the apical lesion and the elimination of inflammation, while the overall long-term treatment goal was the restoration of a clinically successful fixed denture and the preservation of tooth function.
There have been far more advances and changes in clinical endodontic techniques in the decade from 1985 to 1995 than in the last 100 years combined. The major technological advances in clinical endodontics in the last decade have been the emergence and development of four very important treatment techniques: the use of the dental operating microscope (DOM), the use of ultrasonic instruments and nickel-titanium rotary instruments, and the use of mineral trioxide agglomerates (MTA).
Background of previous clinical practice
Dental surgical microscopy
The use of the dental operating microscope (DOM) has enabled the practitioner to achieve superior visualization during clinical root canal treatment. Diagnostically, the dental operating microscope is an indispensable tool for locating cryptic fissures and tracing longitudinally fractured teeth. The use of a dental surgical microscope allows the practitioner to view the intricate structures within the root canal in greater detail, while more effectively examining the complex root canal system and performing root canal cleaning and root canal shaping.
The dental surgical microscope provides excellent resolution to assist the surgeon in bypassing the isolated root canal or removing calculus. The use of the microscope provides a more advanced microsurgical technique, allowing the surgeon to perform smaller debridements, prepare shallow bevels, and locate the isthmus and other irregular root canal anatomy with the help of the microscope, thus increasing the success rate of root canal treatment by an unprecedented 96.8%. The use of a dental surgical microscope significantly improved the localization and detection rate of MB-2 in the second root canal of the proximal mesiobuccal root of maxillary molars. The detection rate was only 52% without the aid of microscopic magnification.
Acoustics
The combination of piezoelectric ultrasound energy and a dental surgical microscope has enabled the use of micro-ultrasound (acoustic and ultrasonic) technology in root canal treatment, which is minimally invasive, effective and precise. Refinement of the pulp opening in a more controlled and predictable manner, precise localization of calcified root canals while reducing the risk of perforation, effective removal of pulp stones attached to the pulp chamber, removal of obstructions in the root canal (separated instruments, root canal stakes, silver tips and metal stakes), as well as removal of stains, biofilm in the root canal and residual infected debris are among the many functions of micro-ultrasonic techniques.
In endodontic surgery, the use of special forms of inverted preparation ultrasonic working tips allows for more effective inverted preparation of the root tip. Thus, during apical surgery, the surgeon is able to minimize the removal of apical tissue structures from the diseased root canal without creating a bevel in the surgical approach. The use of the fiberoptic ultrasonic apical inversion technique consequently reduces the number of exposed dentin tubules and minimizes apical leakage.
Nickel-titanium rotary instruments
Thanks to the advent of nickel-titanium rotary instruments (NiTi), root canal preparation has become more predictable and successful. NiTi is a superelastic alloy with morphological memory properties, so that root canal preparation with NiTi instruments can better maintain the original morphology of the root canal anatomy. Compared to the use of stainless steel files for root canal preparation, the use of nitinol files produces less debris introduction, while the cutting efficiency is enhanced and the time required for root canal shaping is reduced. Nickel-titanium instruments are biocompatible and corrosion resistant, and these properties are not diminished after sterilization. While the all-rotating Nitinol system has been the mainstay of Nitinol systems for many years, reciprocating handpiece motors have taken the market by storm, featuring less chip push-out, faster and smoother access to the root tip, and less instrument fatigue fracture.
Inorganic trioxide polymer MTA
The last of the remarkable technological advances in endodontics during this decade was the advent of the inorganic trioxide polymer MTA, a remarkable, biocompatible restorative material that has been able to become the standard for capping materials, and the use of MTA has saved countless teeth that were previously thought to be unpreserved. We have used MT as a direct capping agent to maintain pulp viability in viviparous pulp preservation treatment and have shown that after 5 months of MTA capping treatment, calcified bridges were formed beneath the capping agent and no inflammation was present in the area.
The results of the study confirmed that MTA is an ideal capping material for live pulpotomy, due to its ability to induce the formation of dentin bridges and to maintain the normal pulp morphology. In addition, MTA also performed well in the choice of inverse filling materials, as there was no inflammation in the apical region after inverse filling with MTA, and the bone structure was preserved, while hard tissue formation was induced. In addition, MTA can repair both perforations in the root divide and lateral root canal penetrations with a high success rate, and the clinician can use MTA inversion fillings from both the crown and root directions to seal defects resulting from internal and external resorption.
The treatment of necrotic teeth with open apical foramina has always been a challenge for dentists, and MTA can serve as a solid and effective apical barrier for such teeth, with open apical foramina and necrotic pulp.
Current status of clinical research
Root canal irrigants and irrigator delivery systems
In recent years, perhaps the greatest international research attention has focused on exploring methods to improve root canal disinfection of the root canal system in endodontic treatment. The properties required for root canal irrigants should include the ability to dissolve necrotic and pulpal tissue, bactericidal ability, broad antimicrobial spectrum, ability to penetrate deep into the dentin tubules, biocompatibility and non-toxicity, ability to dissolve inorganic materials and remove staining layers, ease of use and moderate cost. The combined use of sodium hypochlorite solution and EDTA root canal lubricant has gained worldwide acceptance as an effective disinfectant for the root canal system. Sodium hypochlorite solution is unique in its ability to dissolve necrotic tissue and organic components of the stained layer, in addition to destroying endodontic pathogenic infected tissue sequestered in biofilms. Studies have shown that no other root canal irrigant can meet all these requirements, even when used in conjunction with other methods, such as increasing temperature or adding surfactants to enhance the wetting effect of the irrigant.
Therefore, mineral removal components, such as ethylenediaminetetraacetic acid, are recommended as adjuvants for sodium hypochlorite solutions during root canal treatment, based on their ability to dissolve inorganic dentin particles produced during root canal preparation, while facilitating the removal of the staining layer. In clinical applications, it is very important to note that although sodium hypochlorite solution has excellent properties and meets most of the requirements of a root canal irrigation agent, it still has tissue toxicity and may damage adjacent tissues, including nerve damage, in the event of a sodium hypochlorite incident during root canal irrigation. Because of this, the use of rinse delivery equipment is very important, not only to allow efficient exchange of large amounts of rinse at the root tip, but also to ensure that the rinse is delivered in a safe and efficient manner without pushing it out of the apical foramen.
Root canal irrigation systems are routinely classified into two categories: manual delivery techniques and machine-assisted delivery techniques. Manual irrigation techniques consist of positive pressure push injection, often performed by a lateral opening syringe. Machine-assisted root canal irrigation includes sonic and ultrasonic types, as well as newer systems such as EndoVac (SybronEndo, USA), which features negative pressure (ANP) irrigation of the root tip and plastic rotary F files (PlasticEndo, Lincolnshire, IL); and other systems such as Vibringe (Vibringe BV, The Netherlands), which is a system that provides a high degree of pressure to the root tip. Vibringe BV, Netherlands), the RinsEndo system (Air Techniques Inc., USA) and the Endo-Activator system (DENTSPLY Tulsa Dental Specialties, USA). Of all the techniques listed above, only the Endo Vac system has been able to demonstrate, again and repeatedly, the ability to break the air plug in the apical zone (a column of air generated by the hydrolysis of organic tissue by a sodium hypochlorite solution 3 mm from the root canal), creating a stream of irrigant that removes debris and delivers a large amount of irrigant to the root tip without the risk of pushing the irrigant out of the apical foramen.
Laser
The integrated use of lasers is a viable addition to endodontic equipment, and the use of lasers in endodontic treatment is a potential tool to overcome difficult cases and challenges and achieve successful endodontic results. The special features of the laser are its ability to avoid the painful tremors during pulpotomy, even in pulp-filled teeth where local anesthesia is difficult, and its ability to remove pulp tissue, bacteria, staining layers and dentin debris from the root canal wall during root preparation in a three-dimensional direction through the energy and hydrolysis produced by the laser. In particular, the laser energy is able to penetrate to a depth of 1,000 microns into the dentin tubules. Studies have reported that bacteria can invade to a depth of 400 microns in the dentin tubules, whereas chemical rinses can penetrate to a depth of only 100 microns in the dentin tubules. What is likely to occur clinically is bacterial growth and microleakage. The results of root canal disinfection and the reduction in the amount of bacteria in the dentin tubules will have an unparalleled impact on the success of root canal treatment.
Digital imaging technology
The use of digital imaging technology significantly reduces the waiting time during root canal treatment and also significantly reduces the amount of radiation exposure compared to conventional films. High-resolution digital imaging images are produced instantly and are easy to manipulate to enhance the diagnostic performance of the x-ray images. Digital preservation of images is also very easy, facilitating rapid transmission and communication.
Cone beam computed tomography (CBCT)
What digital imaging technology currently offers us in terms of imaging images, cone beam CT (cone beam computed tomography) CBCT will take us into the future. CBCT technology has been around since the 1980s, but it is only recently that cone beam CT technology has just become a viable radiological examination in root canal therapy. The cone-beam technique uses a cone-shaped beam of radiation in a 360-degree rotation to obtain an overall scan of the irradiated object, similar to that of a curved tomogram. Cone beam CT offers significant advantages over conventional medical CT, including improved accuracy, higher resolution, reduced scan time and lower radiation dose. In the field of endodontics, cone beam CT is often, but not exclusively, used for the diagnosis of odontogenic and non-odontogenic cysts, the differential diagnosis of cysts and granulomas, the localization of missed untreated root canals and the diagnosis of certain root fissures.CBCT can also be used to accurately map the extent of internal resorption, external resorption and cervical resorption of teeth, as well as to accurately measure and evaluate intraoperative anatomical landmarks prior to surgical procedures.
Regenerative Endodontics
Regenerative endodontics has become an exciting possibility where stem cells found in the pulp will regenerate and replace infected tissue with healthy tissue, reviving the pulp. Vascularized regeneration using immature cells from the developing apices of necrotic teeth in the pulp is a very significant challenge for clinicians. Previously, clinical apical inductionplasty was able to maintain root length, but the remaining root canal walls were thin, thus leaving the possibility of tooth root fracture with a high risk. The application of recanalization provides the tooth with a root that not only grows linearly in length, but also thickens the dentin of the root canal wall, resulting in the preservation of the final structure of the natural tooth, thus avoiding the possibility of extraction and implant replacement restoration. At the same time, the recanalization technique is uncomplicated and easy to learn. Through the use of a specially designed mixture of three antibiotics, the induction of blood clots and the tight closure of the crown-side MTA, many pulpal necrotic, undeveloped extranodal teeth are now able to be preserved instead of the previous need for extraction.
Endodontics and Dental Implants
With the advent of implants, patients have been able to maintain their occlusal function and oral health in areas of missing teeth. Unfortunately, implants are also used to replace teeth that are still “viable”. If a tooth is intact but has both periodontal and restorative problems, root canal therapy should be the treatment option of choice. However, if the tooth is missing due to a restorative or anticipated periodontal problem, then we may have to consider dental implants. Treating root canals and conventional root canal retreatment as a first and second choice is more cost effective compared to dental implant treatment. For the current economic basis and cost effectiveness, dental implants are limited to a third treatment option.
The results of many studies support the ability of root canal treatment to achieve perfect clinical outcomes. a study by Kim and Iqbal reviewed the relative success rates of root canal treatment and termination of treatment. The results in the literature showed that the survival rate of single tooth implants and the survival rate of restored teeth after root canal treatment were the same. Both treatment options had an overall success rate of 94% and thus both provided predictable clinical outcomes. However, when compared in terms of use function, dental implants have a relatively long mean survival time and a longer median survival time, which means a high incidence of postoperative complications, i.e. indicating the need for additional and more therapeutic interventions.
Prospects for future developments
Scientific research will increase the peak of development that the specialty of endodontics deserves. The cornerstone of our specialty’s refinement and relevance must be built on a strong foundation of randomized controlled clinical trials and evidence-based endodontic research. The future of endodontics is bright as long as we continue to develop new technologies that allow us to perform painless endodontic treatment with predictable clinical outcomes, thus continuing to meet one of the primary goals of the dental profession, which is to preserve as much of the natural dentition as possible.