Today, successful dentistry can mean multidisciplinary treatment of care, or at least a multidisciplinary approach, with the help of current technology. We have all witnessed how an outstanding endodontic therapy can mean nothing if the restorative plan has not been done properly, or has been delayed. After endodontic therapy, tooth temporization has proven to be one of the weakest links in the longevity of the treated tooth. With CBCT, ultrasound, CAD/CAM and the operating microscope (OM) as weapons of choice, today’s dentists have the ability to turn an endo visit into a single-visit, endo-restorative treatment.

Objectives

At the end of this program, participants will:
1. Understand how microscopes help in endodontics,
2. Understand what advantages CBCT brings to endodontics,
3. Understand the factors involved in determining the best restoration for endodontically treated teeth,
4. Learn how ceramic restorations can be fabricated at the same appointment as the endontic appointment.

Introduction

What’s biology without technology? We want to achieve more, to understand more, to comprehend more, and we ask technology to live up to our expectations regarding these goals. I ask, “Why do today’s children not wear watches?” It’s not because they don’t like wearing watches. The reason they don’t wear them is because a watch is a single-function device, unlike the phone you use, or perhaps the car you drive. We are in a multitasking era, where only time matters. Let’s discuss how we currently use technology in saving a tooth that needs a root canal and subsequent restoration from start to finish. We want to see what we are doing, so we’ll start with the dental operating microscope. Imagine life without magnification. Imagine looking at the earth from space without the ability to see what’s happening beyond the surface. Details are important. We have to observe them before we can understand them. The science of investigating small objects using such an instrument is called microscopy. Any device that enhances or improves a clinician’s resolving power is extremely beneficial in producing precision dentistry.

Dr. Harvey Apotheker introduced the dental OM in 1981. The first OM was poorly configured and ergonomically difficult to use and only capable of one magnification of 8x.
In 1999, Dr. Gary Carr1-3 introduced an OM that had Galilean optics and was ergonomically configured for dentistry. It also had several advantages that allowed for easy use of the scope in nearly all endodontic and restorative procedures. Today, many dentists practicing endodontics rely on an OM to achieve top results.

Despite the use of an OM, there are times when a clinician still will not find a certain canal. In the case below, the DB and the MB2 are obliterated. Despite magnification from the microscope and despite ample effort from the clinician, they are not visible.

Does the dentist keep digging until the fl oor is perforated and he or she ruins the prognosis? Or should the dentist act wisely and send the patient for a CBCT? Obviously, a dentist would use this technology to compensate for limits. The case below gives an example of what a dentist who uses CBCT during endodontics can see. It’s highly doubtful that these canals would be found without the use of a CBCT.

CBCT

What exactly is CBCT? It is a diagnostic imaging modality that provides high-quality, 3D representations of the osseous elements of the maxillofacial skeleton. CBCT systems are available that provide small fi eld-of-view images at low dose with sufficient spatial resolution for applications in endodontic diagnosis,treatment guidance and post-treatment evaluation.4 The pioneering efforts of those using conventional computed tomography (CT) and micro-CT, and the introduction of maxillofacial CBCT in 1996 allowed for the first clinically practical technology which demonstrated the application of 3D imaging for endodontic treatment.5 CBCTs are useful both preoperatively and postoperatively in enododontics.

Preoperative assessment

Imaging achieves visualization of dental and alveolar hard-tissue morphology and pathologic alterations, aiding in correct diagnosis. Imaging provides information on the morphology of the tooth, including location and number of canals, pulp- chamber size and degree of calcification, root structure, direction and curvature, fractures, iatrogenic defects, and the extent of dental caries.
The effects of periradicular and periapical disease can be determined, including the degree of root resorption and characteristics of periapical osteolysis. Larger lesions, only determined by imaging, may necessitate adjunctive surgical procedures in addition to conventional intracanal therapy. Diagnostic radiographs help predict the potential for complications, permit root-fracture detection, and demonstrate periapical lesions.4

Postoperative

A postoperative radiograph immediately after root-canal obturation is made to assess the sealing condensation and containment of the root-canal filling material within the root- canal system. In cases where periradicular healing is incomplete, it acts as a baseline for the assessment of healing in the medium to long term. Imaging is important in evaluating the results of previous therapy, delayed healing, evaluating potential obstacles to retreatment, as well as surgical considerations.6 Success in endodontics is assessed in the healing of the periapical bone adjacent to obturated canals. Research has shown that in evaluating the healing of periapical lesions using 2D periapical radiographs, there was only 47 percent agreement between six examiners. Goldman et al. also reported that when those same examiners evaluated the same films two different times, they had only 19 percent to 80 percent agreement between the two evaluations.

With CBCT, ultrasound, CAD/CAM, and the operating microscope as weapons of choice, today’s dentists have the ability to turn an endo visit into a single-visit, endo-restorative treatment.

The most common pathologic conditions that involve teeth are the inflammatory lesions of the pulp and periapical areas. Dr. Sara Lofthag-Hansen compared the accuracy of three observers using high-resolution, limited-FOV CBCT to intraoral radiographic paralleling technique using two images, one with a horizontal tube-shift difference of about 10 degrees for the diagnosis of periapical pathology on 46 teeth.

While CBCT and intraoral radiographs identified 53 roots with lesions, CBCT identified an additional 33 roots with lesions. Observers agreed that additional clinically relevant material was provided by CBCT imaging in 32 of the 46 (69.5 percent) of teeth imaged. Drs. Andreas Stavropoulos and Ann Wenzel compared CBCT to digital- and fi lm-based intraoral periapical radiography for the detection of periapical bone defects on 10 frozen pig mandibles by four calibrated examiners. They reported that CBCT provides greater diagnostic accuracy (61 percent) compared with digital (39 percent) and conventional radiographs (44 percent).10 The CBCT is an important piece of technology in successful endodontics. So now we have reached the point where the endo is great, thepatient feels great, and everybody’s happy. Now, it’s time for the restoration. Coronal restorations must be considered carefully even before endodontic therapy begins. Very often, what seems to be successful endodontic treatment turns into an extraction because of preexisting unsatisfactory periodontal and restorability situations. All caries and existing dubious restorations must be removed before endodontic treatment, to allow inspection for tooth cracks and the location of sound cavity margins. Something we should keep in mind is that restorative materials, cusp coverage and artificial crowns with ferrules are factors that might significantly influence the subsequent fracture resistance of endodontically treated teeth.

Do we have to cover all the cusps in endodontically treated teeth? What are the limits of the direct technique? All those questions are hard to answer, as there are not enough long-term studies that cover all factors. Many details relevant to the restoration of endodontically treated teeth have been discussed elsewhere.17-18 Increasing the width of the occlusal isthmus, the depth of the preparation, as well as the presence—or lack of—sound enamel, have significant influence on tooth fracture.

Furthermore, the choice of materials selected for the restoration of endodontically treated teeth plays an important role in tooth longevity. Post-endodontic tooth fractures might occur due to loss of tooth structure and induced stresses caused by access cavity preparation, instrumentation, unnecessary cervical dentin removal, irrigation of the root canal, obturation of the instrumented root canal, post-space preparation, and post selection. Coronal restorations, as well as inappropriate selection of tooth abutments for a prostheses, are also factors.12 Although the long-term functional survival of endodontically treated permanent teeth was reported as 97 percent after eight years in a very large epidemiologic survey, coronal and/or radicular tooth fractures continue to remain important reasons for post- endodontic tooth repairs and extractions.13-15 The prevalence of cusp fractures increased significantly with the number of restored surfaces present, and the age of the patients, in particular those over age 55. Failure to replace interim (temporary or provisional) restorations with more-permanent restorations after endodontic treatment resulted in very high tooth losses of 66 percent during a mean follow-up time of three years.

Now what about the question of direct restorations or crowns on posterior endodontically treated teeth?

Many excellent dentists are using direct restoration to restore endodontically treated teeth. Fig. 7 shows a fi rst molar that was restored with resin in this manner. There are many systematic reviews regarding this topic, but nevertheless it’s shown that most of them are retrospective and, as with all retrospective studies, there cannot be a standard clinical study methodology or reporting methodology that will contribute to effective analysis of results. According to the systematic review by Dr. Petros Koidis and others, the results show that teeth that have had root canals and are covered with crowns have a higher long-term survival rate (89 percent).

Why is enhanced vision necessary in dentistry? Any device that enhances or improves a clinician’s resolving power is extremely beneficial in producing precision dentistry.

Now we are going to restore the tooth right after the root canal. Single-visit dentistry is a great service to our patients. This can be done directly with resin, or with the merger of technology and biology—it can be with the use of CAD/CAM technology. CAD/CAM dentistry was developed in 1980 for creating dental restorations. This process allows dentists to construct, produce and insert individual ceramic restorations directly at the point of treatment in a single appointment, rather than multiple appointments with additional lab work. The fi rst applications were successfully carried out on patients in 1985. This technology makes it possible to produce and integrate ceramic restorations in a single appointment. Unlike other materials such as amalgam or gold, ceramic has better aesthetic qualities. In addition, digital impressions can be more comfortable for patients than traditional impressions.

Further clinical studies reveal that the success rate of CAD/CAM restorations is 95.5 percent following a period of nine years, and 84 percent after 18 years.22 The digital mapping technology of CAD/CAM that charts the inside of the patient’s mouth completely accurately and down to the last detail ensures that there are no issues with inaccurate dental impressions, and also cuts down on the negative patient experience of bulky impressions and unnecessary debris in the mouth. In conclusion, technology is playing a significant role in how we treat teeth that need endodontics and their subsequent restorations. Below is a case from start to finish showing technology in dentistry at its best.