Contemporary Restoration of Endodontically Treated Teeth. Nadim Z. Baba
It is therefore important for clinicians to recognize their own limitations when providing any type of dental care and to aim for the best treatment possible for the patient. Referring a patient to a specialist for RCT may provide the best foundation for a good outcome. The following are components of successful RCT that can provide a dependable basis for restoring an endodontically treated tooth.
Diagnosis and Treatment Planning
Successful RCT is based on numerous factors, starting with an accurate diagnosis and appropriate treatment plan. Each individual patient presents with a unique set of conditions that the clinician must manage in order to provide a better oral health status for that patient. The patient’s medical and dental histories provide the background for collecting the necessary information. Because this chapter is about the endodontic aspects of the overall treatment plan, the focus will be on diagnosis as it relates to the status of the pulp, the anatomy of the pulp and the roots, and the conditions affecting these tissues.
Assessment of the pulpal status
Pulpal status is conveniently described as normal pulp, reversible pulpitis, irreversible pulpitis, or pulpal necrosis. However, it can be a challenge to make diagnostic decisions when the examination findings overlap, and a clearcut diagnosis is difficult to make. It is beyond the scope of this chapter to go into detail about endodontic diagnosis; the interested reader will find excellent material in any current endodontic textbook. For practical purposes, we can say that endodontic treatment is indicated when the pulpal diagnosis is either irreversible pulpitis or pulpal necrosis; in some cases, however, it may be prudent to recommend RCT even in situations of normal pulp or reversible pulpitis (Fig 2-2). For example, RCT may be recommended in teeth with normal pulpal conditions or reversible pulpitis if the pulpal health might be compromised by the particular restorative or prosthetic procedure planned.
Fig 2-2 The deep caries lesion may not have invaded the pulp yet, but if placement of a prosthetic crown is planned, it may be prudent to recommend RCT before completion of the prosthetic treatment.
Anatomical considerations
Successful RCT requires a thorough knowledge of tooth anatomy and root canal morphology, both of which can be very diverse.8 Variations occur with respect to the number of roots, the number and shape of canals within these roots, and even the frequency of variations. Numerous factors can account for these variations, such as tooth location, age of the patient, ethnicity, gender, congenital conditions involving tooth development, and even the means of assessment or the definition of what constitutes a canal.9–11
When an endodontically treated tooth is assessed, careful attention should be given to the external root morphology, the number of roots, the shape of the root canal system, and the variations and anomalies that are particular to the tooth. When the internal morphology and obturation are evaluated and compared with the external anatomy, the filled canal shape should match the flow of the external anatomical outline. When endodontic procedures are performed correctly, the external and internal radiographic appearance of the root should be harmonious: The root canal filling should be centered in the root and correspond to the external shape of the root (Fig 2-3).
Fig 2-3 (a) The root canal fillings are centered in the roots, indicating careful attention to root canal morphology and root anatomy. (b) Wellprepared canals correspond to the shape of the root, even when multiple canals are present.
Schilder12 described five objectives for root canal preparation:
1. There is a continuously tapering funnel shape from the apex to the access cavity.
2. Cross-sectional diameters are narrower at every point toward the apex.
3. The root canal preparation flows with the shape of the original canals.
4. The apical foramen remains in its original position.
5. The apical opening is kept as small as practical.
In addition, Schilder12 named four biologic objectives for these preparations:
1. Treatment procedures are confined to the roots.
2. Necrotic debris is not forced beyond the apical foramina.
3. All pulp tissues are removed from the root canal space.
4. Sufficient space exists for intracanal medicaments and irrigants.
These objectives provide a basis for assessing the quality of the endodontic procedure prior to restoration of the tooth. Deviation from the original canal shape is referred to as transportation of the canal. The greater the transportation, the greater the likelihood of a poor endodontic outcome, resulting in the need for either endodontic retreatment or extraction of the tooth.
Root canal systems
The root canal system is complex (Fig 2-4), and its anatomy has been studied extensively for many years. Of special interest in the current context, Weine et al13 called attention to the frequent presence of two canals in the mesiobuccal roots of maxillary molars. Pineda and Kuttler14 and Vertucci15 developed classification systems for canal configurations in individual roots. Research in root canal morphology has led to descriptions of more than 20 canal configurations.11
Fig 2-4 (a) The complexity of the root canal system is well illustrated in these sections of maxillary molars. Note the variety of canal configurations in the mesiobuccal roots and in particular the location of the second mesiobuccal canal in the molar on the right. (b) A radiograph of a maxillary molar seems to show two palatal roots (arrows). (c) On the patient’s request, the tooth was extracted; two palatal roots were identified (arrows).
These considerations are important for the evaluation of a tooth that has undergone RCT. They also point to the challenges inherent to treating teeth with endodontic disease prior to restoration to full function. Achieving full function requires that the treatment-planning process be a teamwork process: RCT can be performed on almost any tooth, but restorability must be determined prior to the endodontic component of treatment. Communication among the various treating dentists before, during, and after RCT offers the best possibility of an optimal outcome.
Assessment of other conditions
Cracked/fractured teeth
Fracture lines involving cusps of teeth have been a problem in dentistry, probably throughout human history. The pain associated with such fracture lines was described by Gibbs,16 who termed it cuspal fracture odontalgia. Every dentist has probably had a patient who complains about pain on chewing and later shows up with the broken-off cusp, usually from a premolar tooth. Whether or not the pulp is directly involved (by exposure), it is usually necessary to complete RCT before the tooth is restored. Diagnosis of a fracture line under a cusp, before it breaks off, can be a challenge and will be discussed in the next section on infractions.
Teeth may develop cracks and fracture for a number of reasons, including trauma, excessive masticatory forces, and iatrogenic incidents. Regardless of etiology, when cracks or fractures develop in dental hard tissues it is not possible to repair them, except for a short period of time with bonding agents. In contrast, bone and cartilage routinely undergo repair following fracture. Although tooth fractures and cracks cannot be healed, it is possible in many cases to maintain such teeth for various periods of time following identification and diagnosis.
For