60 years of dentistry review
60 years of dentistry review
Directed dentin protection (DDC) refers to the preservation of dentin structure, which may play an important role in improving the survival rate of endodontic teeth. Dynamic navigation uses data from CBCT scans to provide real-time visual feedback during cavity preparation. Since the 1990s, the head-up display (HUD) technology of surgical operating microscopes has been used in different medical fields and is reported to improve ergonomics during surgical procedures.
This case report describes the use of dynamic navigation and surgical microscope HUD for modern access cavity preparation and optimal DDC during non-surgical endodontic treatment. It also describes the importance of DDC and the potential advantages and limitations of dynamic navigation and HUD technology for surgical microscopes.
DDC refers to the preservation of selective dentin structure. Clark and Khademi1 suggested that maintaining a high-value selective dentin structure can promote the optimal strength of endodontic teeth (ETT). Valuable dentin areas include cervical dentin (PCD), "soffit" and "truss". PCD includes dentin 4 mm above and below the bone ridge.
It has been suggested that PCD plays a vital role in transmitting occlusal force along the tooth root, and maintaining a complete PCD can be said to be the most important factor in achieving long-term retention of ETT. 2 "Soffit" is the tissue left after the lips of the occluding dentin enter the cavity at the level of the top of the pulp cavity.
A "truss" is a set of dentin at the top of the pulp cavity that supports the buccal and lingual structures of the teeth and improves resistance to tensile and compressive forces. Both soffits and trusses may contribute to the overall strength of ETT.3
The use of preoperative CBCT scans to determine the root canal convergence curve was previously described to plan the orifice-oriented approach to maintain maximum PCD, soffit, and truss. 3
Dynamic Navigation (DN) uses data from CBCT scans to guide clinicians during dental surgery. The overhead stereo camera tracks the position of the markers attached to the dental handpiece and the patient's chin. The position of the tip of the instrument is displayed on the virtual dentition of the patient on the screen interface of the system. When the clinician moves the instrument in the clinic, the virtual representation of the instrument moves on the screen to provide real-time guidance.
Gambarini et al. describe more details about the DN workflow. 4 In the past few years, DN was mainly used to improve the accuracy of dental implants. Recently, the potential benefits of DN in improving the accuracy and efficiency of non-surgical and surgical endodontic surgery have been studied.
For decades, the high magnification and high illumination of the surgical operating microscope (SOM) has been a valuable tool in different medical fields and endodontics. Carr and Murgel5 discussed the benefits of SOM in dentistry, including improved ergonomics and photo documentation.
Over the years, SOMs used in different medical fields have evolved to incorporate HUD technology. In the 1990s, the first microscope with HUD function was introduced to facilitate image-guided neurosurgery. 6 HUD in SOM involves injecting virtual images into the clinical field of view seen through binoculars.
The injected superimposed image includes patient data, such as preoperative imaging of interest or data from a navigation system. Combining HUD is believed to improve ergonomics during medical surgery, because clinicians can visualize valuable information through superimposed virtual images and directly visualize the surgical area itself. 7 As far as the author knows, the clinical use of HUD in the field of SOM has never been reported in dentistry.
A 62-year-old woman with no medical history presented to the author's clinic with the main complaint of chewing pain in the upper right posterior area that began a month ago. Clinically, the No. 3 tooth adopts an occlusal composite resin restoration, showing leakage and crack lines at the mesial and distal ridges (Figure 1a). Two-dimensional imaging interpretation showed that there was no convincing root apex discovery and deep repair, indicating that the coronal fissure is a potential cause (Figure 1b).
The patient was referred for a small-field CBCT scan. The interpretation of the CBCT volume revealed the periapical findings at the top of the palatal root of tooth 3 (Figures 1c and 1d). The third tooth was diagnosed with pulp necrosis and symptomatic apical periodontitis. The treatment plan was discussed, and the patient agreed to use the Navident system (ClaroNav) for non-surgical endodontic treatment under the guidance of DN.
In order to maintain as much PCD and dental pulp top dentin as possible, Navident software was used to plan 3 independent entry cavities according to the root canal convergence profile: one to the distal (DB) root canal and one to the palatal (P) root canal Mouth, one to the proximal cheek (MB1) root canal opening (Figure 1e to 1g).
After local anesthesia, complete the DN registration and calibration procedure: After placing the rubber dam for isolation, place the Navident fiducial mark on the maxilla and register the dentition so that the CBCT data can be incorporated into the actual clinical field.
Then calibrate the mobile phone and bur according to the Navident protocol. The entry cavity using DN is prepared under SOM, and the experimental HUD prototype (Zumax Medical Co, Ltd) (Figure 2a and 2b) is used, and the #859.31.010 needle cone diamond bur (Brasseler USA) is used.
Figure 2c shows the access cavity preparation and simultaneous DN of the DB tube observed through SOM binoculars. After completing the preparations for the linear pathways of the MB1, DB, and P canals, the pre-planned digital pathway of the MB1 canal was readjusted to the angle towards the MB2 canal (Figure 3).
Then use DN and SOM HUD to enter the MB2 canal in the same way. The Ryder S3 electronic vertex locator (MedicNRG) was used to obtain the glide path and working length. Use the DCTaper Rotary File System (SS White Dental) to perform instrument inspection on #20.06 in the buccal canal and #25.06 in the palatal canal. Use full strength (8%) sodium hypochlorite and EndoActivator (Dentsply Sirona) to complete the disinfection. Dry the root canal with a paper tip and administer calcium hydroxide.
Temporary cavity filling material (3M) and composite resin restoration were used to temporarily repair the entry cavity on the coronal surface. The patient returned after 4 weeks and the teeth were completely asymptomatic and functioning normally. Use AH Plus sealant (Dentsply Sirona) to warm and vertically compact the gutta-percha, re-enter and close the canal. Figures 4a to 4c show 3 separate orifice guided entry cavities with maintenance of the dental pulp top dentin. After applying 37% etching agent, use Futurabond DC (VOCO) and LuxaCore Z Dual (DMG America) to permanently restore the teeth.
Proposals for indirect restoration of onlays are put forward. Figure 4d shows the postoperative X-ray, showing conservative access to the cavity, preservation of the PCD, and truss (black arrow).
Although it has aroused the interest of clinicians all over the world, the minimally invasive method of preparing the endodontic cavity is still a controversial topic. The conclusions of in vitro studies are often cited against minimally invasive endodontic treatment. 8 Unfortunately, the inherent limitations of these in vitro studies using mechanical failure experiments make it very unreliable to translate the results of bench-top experiments into clinical situations. 9
Decades ago, the medical profession's long-term concern about the necessity of surgical invasiveness led to the eventual acceptance of minimally invasive treatment. 10 In fact, the removal or manipulation of additional human tissue during various surgical procedures should be justified by a provably and convincingly high level. Level of evidence. In endodontics, the responsibility for demonstrating benefits should be borne by those who advocate the removal of more dentin during the preparation of the cavity rather than those who advocate less.
Randomized controlled trials are the most powerful source of evidence to guide clinicians to make decisions for different clinical interventions. 11 Unfortunately, no such clinical studies have shown that the minimally invasive approach to cavity preparation may have advantages over traditional methods or vice versa.
On the other hand, the evaluation of the next best available evidence, including observational clinical studies with medium and long-term follow-up periods, shows that this is not the case. 12-21 These studies consistently report that the main reasons for extracting ETT usually include recurrent dental caries or restorative, structural or periodontal failures, with the least reported failures of true pulp origin.
These findings indicate that DDC should be one of the main goals of endodontic treatment to achieve longevity of teeth. With the advent of new technologies, such as heat-treated rotary burrs, CBCT, DN, and improved irrigation and containment methods, it is now possible to overcome the limitations of traditional access cavity design requirements in the past.
The experimental HUD prototype used in this case report includes a display device that superimposes the mirror image of the Navident computer screen (Figure 4e) directly into the clinical field of view in real time, such as using a customized SOM optical module. Future applications of HUD in SOM include injecting apex locators to read data or preoperative imaging of interest, and using artificial intelligence and image processing to cover virtual 3D models of tooth structures.
This case report also demonstrates the use of DN to obtain the best DDC. DN allows the planning and execution of an ideally designed entry cavity to maintain as much PCD and pulp crest as possible while still achieving the biological goals of endodontic treatment. Based on the root canal convergence profile, each root canal orifice has a separate linear path, which allows the use of heat-treated NiTi rotary files for safe instrument operation.
Although an experienced clinician can usually achieve the same procedural results using bare hands to enter the cavity preparation, DN has the potential to simplify the process and significantly reduce treatment time and frustration.
Another guided endodontic treatment method involves the use of 3D printed static guidance. Potential limitations of static guides in endodontics include the lack of occlusal spacing to accommodate longer drill bits, the inability to use high-speed drills or burs, and the waiting time involved in manufacturing static guides, which makes the same-day endodontic treatment. The need to manufacture multiple guides to access all root canals of multiple teeth, and the inability to easily change the treatment plan based on new clinical information or challenges during the guidance process is also a limiting factor. twenty two
DN usually does not have these restrictions. In fact, an access cavity can be planned within a few minutes, making DN an ideal choice for emergency treatment. The Navident system can be used with many different instrument tips, including high- and low-speed burs, ultrasonic tips, or piezoelectric surgical tips. In addition, DN allows immediate changes to the treatment plan during surgery (Figure 3).
The accuracy of DN for endodontic treatment has never been evaluated in vivo. The summary results of in vitro studies in the field of dental implants and endodontics and the results of in vivo studies of dental implants show that the current error range of DN is about 0.5 to 1 mm. 23-29
Although DN provides tremendous benefits in improving the accuracy of different clinical procedures, its current margin of error is still high for endodontic applications. In addition, in accordance with the recommendations of the manufacturing company, the current workflow of DN involves the clinician's attention being completely focused on the computer screen interface of the system, which is located far away from the surgical area.
Because the clinician is fully focused on the DN during the preparation of the cavity entry, other valuable information such as direct visual feedback from the dentin map is not accessible. With HUD, clinicians can use DN as an auxiliary tool without having to look away from the surgical area. This freedom allows clinicians to selectively focus on different valuable information without any compromise, and can help improve the accuracy of cavity preparation with the best DDC, rather than using DN alone.
In addition, for clinicians who are accustomed to seeing the surgical field through SOM, having to look up at the computer screen during DN surgery may feel unnatural.
At the same time, combining the advantages of DN and SOM can also minimize wasted actions and time, and maximize ergonomics.
This case report demonstrates the potential of DN to efficiently and safely prepare the pulp into the cavity with maximum DDC. SOM HUD further demonstrated the enhanced ergonomic design. Future clinical studies are needed to determine the accuracy of DN for pulp access cavity preparation.
The author would like to thank Drs. Thanks to Viraj Vora and Dale Jung for helping review the manuscript.
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Dr. Nadeau graduated from Dalhousie University with a degree in DDS and a master of science degree in endodontics from the University of Toronto. He has a special interest in the dynamic navigation of endodontics, the ergonomics of microscope dentistry, restoration-driven endodontics and clinical decision-making. Dr. Nadeau is in full-time private practice in Kingston, Ontario, Canada. You can contact him at bnadeau29@gmail.com.
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