© Springer International Publishing AG 2018
Thomas Kvist (ed.)Apical Periodontitis in Root-Filled Teethdoi.org/10.1007/978-3-319-57250-5_4
Department of Endodontology, Institute for Postgraduate Dental Education, Jönköping, Sweden
Department of Endodontology, Institute of Odontology, The Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden
Persistent or emerging apical periodontitis is a common finding in root-filled teeth. The consequences thereof may have implications for the patient in terms of pain, tooth loss, spread of infection and additional costs. However, inconclusive data from several studies also suggests systemic effects of apical periodontitis. Obviously, these pathologies will correspondingly influence the everyday work of dentists. Also, it may have consequences for society and third-party payers. From a cost-benefit point of view, it is not unequivocal which should be the treatment of choice when a root-filled tooth is diagnosed with apical periodontitis.
Science is the knowledge of consequences, and dependence of one fact upon another.
Thomas Hobbes (1588–1679). English philosopher
Chapter 2 thoroughly reviewed the incidence and prevalence of apical periodontitis in root-filled teeth. From this it stands clear that, even though there may be many reasons to question the exact numbers in single studies, a great many root-filled teeth present with signs of apical periodontitis. Considering the great number of root-filled teeth in populations with access to dental care, the condition is found in every other adult. In this chapter we will scrutinize the consequences of apical periodontitis in root-filled teeth.
4.2 Different Types of Consequences and Different Stakeholders
A fact may have different consequences and affect different parties. Three main categories of consequences without clear boundaries between them may be identified in relation to apical periodontitis in root-filled teeth: biological, psychological and economic. Obviously, it seems most important to investigate the consequences for those directly affected by the condition, the patients. However, also their doctors, the dentists, will be affected, since the situation is supposed to be handled with in some way or the other. Thirdly, also third-party payers like reimbursement organizations, insurance companies or public and tax-funded health organizations are affected by apical periodontitis in root-filled teeth. In the following we will discuss the different categories of consequences from different point of views.
4.3 Consequences for Patients
184.108.40.206 Persistent Pain
Surprisingly little is known about the frequency of pain from root-filled teeth. From the obtainable data in follow-up studies from university or specialist clinics, in a systematic review, the frequency of persistent pain >6 months after endodontic therapy was estimated to be 5% . In this context it is also important to point out that a painful condition associated with a root-filled tooth not necessarily is due to the presence of apical periodontitis [2, 3].
220.127.116.11 Flare-Ups of Asymptomatic Lesions
The incidence and severity of exacerbation of apical periodontitis from root-filled teeth have met only scarce attention from researchers. A low risk of painful exacerbations (1–2%) was reported from a cohort of 1032 root-filled teeth followed over time by Van Nieuwenhuysen et al. . In a report from a university hospital clinic in Singapore where 127 patients with 185 non-healed root-filled teeth were recruited , flare-ups occurred only in 5.8% over a period of 20 years. Less severe pain was experienced by another 40% over the same time period. The incidence of discomforting clinical events was significantly associated with female patients, treatments involving a mandibular molar or maxillary premolar and preoperative pain.
18.104.22.168 Local Spread of Disease
It is well known that odontogenic infections may have the potential for life-threatening spread to other parts of the body . In a study from the United States approximately 61,000 hospitalizations of patients were primarily attributed to periapical abscesses during a 9-year study period . The mortality was reported to be approximately 1‰ (66 patients). In a study from Finland, Grönholm et al.  evaluated clinical and radiological findings in a group of 60 patients with hospital stay due to periapical periodontitis. They found that unfinished root canal treatment was the major risk factor for hospitalization. Root-filled teeth with apical periodontitis were the source only in 7 (12%) of the 60 cases. It has been calculated that the amount of root-filled teeth only in United States is about 420 million  and that approximately 36% of these present with signs of apical periodontitis . Pooling the information from these different sources would result in an estimated risk of severe event, requiring hospitalization, because of a root-filled tooth with apical periodontitis to be approximately 1 in 200,000 on a yearly basis.
22.214.171.124 Loss of Tooth
Two longitudinal studies in Scandinavian populations found that 12–13%, respectively, of the teeth that were root filled at the base-line examination were extracted at follow-up approximately 10 years later [11, 12]. In the Danish population, it was found that teeth with apical periodontitis (non-root filled and root filled) had a six times higher risk of being lost than teeth without apical periodontitis . In a selected Swedish population, the 20-year survival rate of root-filled teeth was 65% . The finding of apical periodontitis at baseline was among variables associated with low odds for tooth survival. However, it is difficult to tell whether the observed correlations are causative or a consequence of biased selection of cases for extraction. Observations from other studies suggest that other causes than apical periodontitis such as periodontal disease, caries or root fracture are frequently present when root-filled teeth are extracted [15, 16].
126.96.36.199 Systemic Effects
The possible association between systemic diseases and inflammatory processes of endodontic origin has been debated for more than 100 years. However, evidence is poor, and only a few scientific studies of good quality are available .
A possible correlation between apical periodontitis and cardiovascular disease (CVD) and coronary heart disease (CHD) , respectively, has been of certain focus. One study found an association between apical periodontitis and CHD in middle-aged and younger men (<40) over a 32-year period . In one cross-sectional study, an analysis of female patients demonstrated no increased risk of CHD among those with apical periodontitis, after adjustment for established risk factors . Yet another study comprised analysis of a large number of health professionals receiving medical care . A weak association to CHD was reported with respect to individuals with one or two root fillings.
One case-controlled clinical trial showed a positive association between the number of inflammatory lesions of endodontic origin with acute myocardial infarction or unstable angina compared with healthy controls . One study evaluated whole-body computed tomography examinations of 531 patients retrospectively. The atherosclerotic burden of the abdominal aorta was quantified using a calcium scoring method. Chronic apical periodontitis correlated positively with the aortic atherosclerotic burden. In regression models, apical lesions in teeth without endodontic treatment were found to be an important factor but so did not apical radiolucencies in root-filled teeth . One study investigated whether an association between chronic oral infections and the presence of an acute myocardial infarction exists. The results showed that patients, who have experienced a myocardial infarction, had more missing teeth and a higher number of inflammatory processes of endodontic origin than healthy individuals . In a retrospective study the presence of apical periodontitis and root-filled teeth was associated with long-term risk of incident cardiovascular events, including cardiovascular-related mortality . Finally, in a pair-matched, cross-sectional designed study, subjects with apical periodontitis were more likely to have CVD than subjects in the final adjusted logistic regression model .
Other systemic diseases that have attracted attention are diabetes mellitus, chronic liver disease and different types of blood disorders .
At present time the association between endodontic disease and different systemic conditions rests on shaky scientific ground. However, the thinkable biological mechanisms behind a link are present . It is obvious that relationships between endodontic infections and general health and well-being should be in focus of future research in endodontology.
4.3.2 Psychological Consequences
The psychological effects include aspects of knowledge, beliefs, attitudes, values, preferences, quality of life and satisfaction. Quality of life is concerned with the degree to which a person enjoys the important possibilities of life . Surprisingly few studies have addressed these “patient-centred” outcomes of endodontic treatments . Disease of pulpal origin negatively affects quality of life primarily through physical pain and psychological discomfort, and root canal treatment results in distinctive improvement .
The impact on daily life activities (eating, speaking, sleeping, contact with people, etc.) by painful exacerbations of persistent periapical lesions in root-filled teeth was reported in the previously mentioned study from Singapore . Among the 127 patients with apical periodontitis in a root-filled tooth recruited for the study only 33 patients (38 teeth) had experienced some kind of impact over a period 38 years. But only five patients reported substantial impact.
The attitudes towards asymptomatic persistent lesions among patients affected have only met scarce attention. In two studies value judgements towards an asymptomatic root-filled tooth with a periapical lesion were investigated by methods used in the context of expected utility theory [30, 31]. In both studies elicited subjective values towards asymptomatic apical periodontitis and root-filled teeth showed great variation.
4.3.3 Economic Aspects
A great many teeth with pulpitis and apical periodontitis, even in countries with well-developed dental care, often do not come under dental treatment. They remain unrecognized, because they are asymptomatic or are considered among the ordinary discomforts of daily living. Or, the patient may be suffering from both pain and other symptoms for a prolonged period of time but because of economic limitations has not been able to seek dental care . Cost is a significant barrier to receiving dental care and a very important factor in patients’ treatment choices. The “willingness to pay” for root canal treatment in order to save an asymptomatic nonvital lower first molar was studied in a population of 503 patients in England . Only, 53% of the sample wished to save the tooth with a mean “willingness to pay” of £373. The variation in willingness to pay was found to be substantial and influenced by income. Initial cost may capture patients’ attention, but that is only the beginning. The original cost of tooth retention through root canal treatment and restoration is usually considered to be lower than tooth replacement using implants or fixed dental prostheses . However, the lifetime cost model for different options should also include treatment failures. In a cost-effectiveness model from the United Kingdom, regarding a maxillary incisor, it was calculated that saving a tooth by root canal treatment, followed by non-surgical retreatment if indicated, was cost-effective. However, surgical retreatment was not found to be cost-effective . On the other hand, an American cost-effectiveness modelling study, for a root-filled treated molar in need of re-intervention, ranked surgical retreatment, non-surgical retreatment, replacement using a fixed dental prosthesis and replacement using an implant, from the greatest to smallest cost-effectiveness . There are several problems involved in using these data in a clinical situation for an individual patient’s point of view. First of all, the calculations are highly sensitive to different care providers’ fees for the interventions put into the algorithms. Secondly, it is possible that the benefits available under the prevailing dental care reimbursement system encourage one of the options at the expense of the other regardless of cost-effectiveness in the long term. Thirdly, cost-effectiveness analyses compare relative costs and outcomes but do not take into account individual patient values. One can, with good reason, assume that individuals who already paid for root canal treatment once are reluctant to pay for retreatment, in particular, if the tooth is asymptomatic. Data from the many epidemiological studies, showing that root-filled teeth with persistent apical periodontitis are very common, suggest that patients and their dentists, in many cases, assess the cost-benefit ratio to be too low to undertake any operation whatsoever.
4.4 Consequences for Dentists
The high prevalence of apical periodontitis among adult patients is a challenge for dentists in several ways. In the following, some important issues, from the dentist’s point of view, will be briefly mentioned. Most of these aspects are more thoroughly addressed in the other chapters of this book. Here, some aspects not covered elsewhere are discussed.
When a patient presents with a root-filled tooth causing pain and swelling or chronic clinical findings in the form of redness, tenderness and fistulas, it is usually relatively straightforward to diagnose a persistent, recurrent or arising apical periodontitis. However, the most common situation is that the root-filled tooth is both subjective and clinically asymptomatic but an X-ray reveals that bone destruction remains. It is difficult to determine how long is the time that may be required for such a healing process in a particular case. The diagnosis of periapical tissues based on intra-oral radiographs has repeatedly unmasked considerable inter- and intra-observer variation. Besides the time aspect and observer variation, there is also a problem of determining what should be considered as a sufficient healing of bone destruction to constitute successful endodontic treatment. And as a consequence also what establishes a “failure” and hence an indication for retreatment is far from unambiguous.
According to the limited data available in the literature, claims concerning endodontics are common among dental professional liability cases [37, 38]. The high prevalence of root fillings of poor quality, as pointed out in numerous studies, makes this hardly surprising. However not all claims are justified. All healthcare, including endodontics, need to weigh the benefits of various measures against the risks. The goal of all dental care is of course that it will be of benefit to those who receive it. But sometimes the procedures per definition are resulting in injuries or damage. Some “damage” is planned, as when the affected tooth is opened by removal of hard tissue in order to get access to the root canal system. Unnecessary injuries may occur as a result of incompetence, negligence or by a single mistake. Even the most skilful, well-educated and experienced dentist can make mistakes sometimes. Some endodontic treatments can also be very complicated, with more built-in risk for complications than others. These injuries are regrettable but are an inherent risk of endodontic procedures that one can seek to reduce over time through improved treatments, better education and more hands-on instruction. But injuries that occur because of carelessness, incompetence or because the caregiver has not complied with in the scientific and technological developments in the profession are avoidable in a completely different way and cannot be viewed as acceptable. And as a result of quality deficiencies in the primary endodontic treatment, a suspicion or accusation of malpractice may emerge when a persistent apical periodontitis is diagnosed in a root-filled tooth.
When treating diseases of infectious and inflammatory disease emanating from the pulp, unsuccessful outcome may occur despite professional excellence in every detail. It is of paramount importance to inform about the possible risks of the treatment procedures and explain that treatment may not always lead to a successful result, even though it is performed in accordance with all the rules. This should be a part of the informed consent procedure. A malpractice claim might be perceived as a criticism of the dentist’s competence and skills but also as a sign of a downfall in communication with the patient.
If a root canal treatment “failure” is diagnosed despite a reasonable high-standard treatment procedure, and the patient understands and accepts the situation, there is also little to argue about. The problem is limited to a decision-making problem if and how the pathology should be treated.