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Foraminal enlargement analysis

Drs. Carlos Henrique Ferrari, Frederico Canato Martinho, Ricardo Machado, and Leticia Aguiar analyze the benefits and risks of intentional foraminal enlargement, considering the impact both locally and systemically

n recent years, has seen a Iconsiderable paradigm shift as a result Educational aims and objectives of technical and scientific developments. This clinical article aims to make a critical analysis, based on the literature, to assess the However, the concept of shaping and advantages and disadvantages and the local and systemic risks related to the intentional enlargement of the . cleaning (Schilder, 1974) remains one of the pillars of the specialty especially when Expected outcomes dealing with infected canals. Endodontic Practice US subscribers can answer the CE questions on page XX to Historically, the literature has demon- earn 2 hours of CE from reading this article. Correctly answering the questions will strated how anatomical complexities make demonstrate the reader can: it so difficult to adequately shape and clean • Realize that there is no scientific evidence to support intentional foramen enlargement in humans. the system, especially the apical • Recognize that the methodological design of future studies for performing this procedure should be one-third (Paqué, et al., 2009; Paqué, et undertaken with caution, because the literature consulted in this paper reiterates that intentional foraminal al., 2010). Furthermore, in some cases, enlargement poses both local and systemic risks. endodontic infection extends beyond the limits of the apical constriction, for example, to the apical foramen or beyond (extraradical has postulated that apical patency can clear et al., 2000; Marroquín, et al., 2004; Abarca, biofilm) (Noiri, et al., 2002; Chavez De Paz, the apical foramen and promote micro- et al., 2014). 2007; Ricucci, Siqueira Jr, 2010). In these biological disruption in this area, using a Several clinical studies have shown situations, intentional foraminal enlargement small caliber instrument to lightly touch a high frequency of instrument fracture in may be performed to decrease the micro- the walls of the apical foramen (Buchanan, the apical third when anatomically complex bial load to levels more favorable for repair 1989; Cailleteau, Mullaney, 1997; Flanders, and narrow canals are present (Ehrhardt, et (Borlina, et al., 2010). Previous studies have 2002; Souza 2006; Coutinho–Filho, et al., al., 2012; Madarati, et al., 2013). Moreover, shown encouraging results for intentional 2012; Mounce, 2015). However, intentional especially when dealing with posterior teeth, foraminal enlargement, enabling more effi- foraminal enlargement is performed with the apical foramen may be located laterally to cient mechanical action of instruments and different techniques and instruments and the anatomical apex (Pineda, Kuttler, 1972), the chemical action of irrigating solutions (de consists of the mechanical enlargement and intentional foraminal enlargement may Souza Filho, et al., 1987). of the apical foramen for the purpose of predispose to weakening of the with a Therefore, the purpose of this paper decontamination by excising infected higher incidence of fracture. was to perform a critical literature review by and (Borlina, et al., 2010; Silva, Another factor limiting foraminal enlarge- analyzing the likely benefits and risks of inten- et al., 2013). Accurate intentional foraminal ment is the clinician’s inability to achieve tional foraminal enlargement, considering the enlargement requires the shape and diam- apical potency of the apical foramen in impact both locally and systemically. eter of the apical foramen to be accurately some situations. This may occur because assessed and measured. Clinically, this of abrupt curvatures, the existence of two or Local effects would seem to be impossible (Dummer, et more main apical foramina, apical deltas, or Anatomical considerations al., 1984; Abarca, et al., 2014). Conven- complete or incomplete isthmuses (Meder– Undeniably, necrosis and peri- tional endodontic instruments are unable Cowherd, et al., 2011; Verma, Love, 2011; radicular lesions are an indication that the to perform this, because of the oval shape Villas–Bôas, et al., 2011). entire length of the root canal is contami- of the apical foramen (Goldberg, Massone, Considering all the facts and appreciating nated (Ricucci, Siqueira Jr 2010, Tronstad, 2002; Marroquín, et al., 2004; Herrera, et al., that foraminal enlargement is a plausible idea et al., 1990; Nair, et al., 2005, Siqueira, 2011; Akisue, et al., 2014). Consequently, from a microbiological standpoint, it cannot Rôças 2008). For this reason, the literature adequate cleaning cannot be achieved (Wu, always be performed. In controlled clinical studies with robust samples and appropriate Carlos Henrique Ferrari, DDS, is a PhD endodontic student at São Jose dos Campos Dental School, State University of São Paulo inclusion and exclusion criteria (Imura, et al., – UNESP, São Jose dos Campos, São Paulo, Brazil. 2007; Ricucci, et al., 2011; Liang, et al., Frederico Canato Martinho, DDS, MSc, PhD, is a professor of endodontics at São Jose dos Campos Dental School, State 2013), there have been no reports of inten- University of São Paulo – UNESP, São Jose dos Campos, São Paulo, Brazil. tional foraminal enlargement in the clinical protocols adopted. Nonetheless, the success Ricardo Machado, DDS, MSc, PhD, is a professor of multidisciplinary clinic I and II and supervised stage in multidisciplinary clinic I (endodontics), Paranaense University – UNIPAR, Francisco Beltrão, Paraná, Brazil. rates of these studies are high even in cases of pulp necrosis with radiographically visible Leticia Aguiar is a graduate student from Paranaense University – UNIPAR, Francisco Beltrão, Paraná, Brazil. periradicular disease (Imura, et al., 2007; Ricucci, et al., 2011; Liang, et al., 2013).

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Extrusion of sodium hypochlorite, calcium cements (Strindberg, 1956; Engstrom, 1964; et al., 1995; Moinzadeh, et al., 2013). These hydroxide, and filling materials Yusuf, 1982; Nair, et al., 1990; Sjögren, et al., statements are based on bisphosphonates Sodium hypochlorite is the most widely 1990; Orstavik, Hörsted–Bindslev, 1993). interfering directly with the bone remodeling accepted and used irrigant solution world- It is important to consider the hypoth- process and inhibit the chemical mediators wide (Stojicic, et al., 2010; Zou, et al., 2010; esis that the greater the enlargement of the of the inflammatory process (Katz, 2005; Wong, et al., 2014; Guneser, et al., 2015). apical foramen, the greater the possibility of Edwards, et al., 2008). Nonetheless, it has a highly adverse effect after extrusion of any substance used in the root When considering the need for endo- extrusion into the periradicular tissues or maxil- canal (Hülsmann, Hahn, 2000). Neverthe- dontics in patients who are or have been using lary sinus, or when injected into the gingival less, more research is required to confirm bisphosphonates recently, it seems obvious mucosa (Pashley, et al., 1985; Gatot, et al., this hypothesis. that intentional foraminal enlargement is a 1991; Ehrich, et al., 1993; Kavanagh, et al., completely contraindicated procedure. 1998; Kleier, et al., 2008; de Sermeño, et al., Systemic effects 2009; Wang, et al., 2010; Kerbl, et al., 2012). Patients who are taking or have taken Patients with coagulation disorders or using The most common consequences of bisphosphonates recently anticoagulants this type of accident are the following: (Huls- Bisphosphonates are drugs used to treat Homeostasis in healthy patients is asso- mann, Hahn, 2000; Serper, et al., 2004). bone diseases and prevent tumour metas- ciated with four main factors: • severe pain tasis (Moinzadeh, et al., 2013). Their exten- • walls • instant inflammation of the affected sive use is directly related to osteonecrosis • Blood platelets area of the jaw after performing dental procedures • The coagulation system • swelling extended to the face, lips, (Katz, 2005; Sarathy, et al., 2005; Edwards, • The fibrinolytic system and infraorbital region et al., 2008; Moinzadeh, et al., 2013). Since Blood vessel constriction is the first • hemorrhage descending from the these drugs are widely used today, dentists stage, followed by platelet adhesion and root canal should be knowledgeable about some likely aggregation, and by fibrin deposition. In • interstitial hemorrhage with skin and effects that can influence the prognosis of the next stage, the coagulation process is mucosa bruising the treatment. regulated by physiological anticoagulants. • secondary infection, Specifically related to endodontics, some Activation of fibrinolysis is triggered by the • paresthesia important precautions should be borne in mind: presence of fibrin and tissue plasminogen The use of calcium hydroxide as an inter- • Antiseptics, such as chlorhexidine, activator-types at the site of fibrin formation, appointment dressing can have adverse conse- must be used to reduce the bacte- a process regulated by physiologic inhibitors quences if it is accidentally extruded beyond rial load of the oral cavity (Cousido, such as 2-antiplasmin, histidine-rich glyco- the apical foramen (Fava, 1993; Marais, Van et al., 2010) and the risk of bacte- protein, and plasminogen activator inhibitor Der Vyver, 1996). Fava (1993) as well as Marais raemia, due to possible injury to soft (DeLoughery, 1999; Scully, Wolff, 2002). and Van der Vyver (1996) reported cases of tissues during the course of treat- This process is completely different in calcium hydroxide extrusion into the maxillary ment (Moinzadeh, et al., 2013) patients with a coagulopathy or taking anti- sinus, causing acute pain and a foreign body • Anesthetics with vasoconstric- coagulants because of the risk of exces- reaction. Ahlgren, et al., (2003), reported a tors should be avoided because sive bleeding, even from a gentle stimulus. case of calcium hydroxide extrusion into the the vasculature is compromised, Gingival bleeding during tooth cleaning may mandibular canal with acute pain and pares- constituting a greater risk for osteo- cause these patients to neglect their oral thesia. Other adverse consequences associ- necrosis, as bisphosphonates exert health, thus increasing the risk of perio- ated with the extrusion of calcium hydroxide are an antiangiogenic effect (Tarassoff, dontal disease and caries. For this reason, neural injury (Olsen, et al., 2014), severe peri- Csermak, 2003; Soltau, et al., 2008; dentists should be knowledgeable about radicular inflammation requiring the extrac- Moinzadeh, et al., 2013). the impact of blood disorders or the use tion of the involved tooth (Hanson, Macluskey, • Special care must be taken to of anticoagulants in treating these patients 2013), and the persistence of periradicular reduce damage to the gingival (Johnson, Leary, 1988; Shapiro, McKown, lesions (Ionnidis, et al., 2010). tissue (Kyrgidis, Vahtsevanos, 2009; 1990; Gupta, et al., 2007). Certain filling materials (mainly solids) are Moinzadeh, et al., 2013) In patients with coagulation disorders also responsible for several extrusion-related • Filling techniques must be prioritized or taking anticoagulants, and needing tooth complications, such as radiographically to pose the lowest risk of overfilling extraction, conventional endodontic treatment visible foreign body reactions, flare-ups, and and overextension (Liang, et al., or retreatment should be the preferred option postoperative pain exacerbated by the acti- 2011; Moinzadeh, et al., 2013) whenever possible. However, the shaping vation of an inflammatory response (Oliet, According to Katz (2005) and Edwards, and cleaning process must be confined to 1983; Rowe, 1983; Georgopoulou, et al., et al., (2008), one of the main precautions in the limits of the root canal (Chohayeb, 1981), 1987; Siqueira, 2003; Nair, 2004; Saleh, et al., relation to patients who are making use or and intentional foraminal enlargement would 2004; Seltzer, Naidorf, 1985; Gluskin, 2005; have recently made use of this class of drug be completely contraindicated. Köseoglu, et al., 2006; González-Martín, et is to establish a working length near the apical al., 2010; Faria-Júnior et al., 2013; Alves, et constriction and to decrease the extrusion of Patients with a high risk of bacteremia al., 2014). All materials extruded beyond the debris and exacerbated inflammatory reac- Several systemic complications from apical foramen are irritating to the periradicular tions during and after treatment. Even foram- oral infections have been reported. Some of tissues to a greater or lesser extent. There is no inal patency should be avoided (Moinzadeh, the most common include bacterial endo- scientific evidence warranting the intentional et al., 2013) because it can considerably carditis; myocardial infarction; cerebral extrusion of irrigating solutions, pastes, and increase the chances of bacteremia (Debelian, abscess; bone, antral, and bloodstream

Volume 9 Number 1 Endodontic practice 27 CONTINUING EDUCATION

infections (Baumgartner, et al., 1976; frequently been shown, regardless of the between using manual and rotary instrumen- McGowan, 1982; Bender, Montgomery, systems and techniques used (Reddy, Hicks, tation were found in relation to the extruded 1986; Debelian, et al., 1994; Murray, Saun- 1998; Bürklein, Schäfer, 2012; Koçak, et al., debris. However, both techniques showed a ders, 2000; Scully, et al., 2003). 2013; Kirchhoff, et al., 2015). strong tendency to produce greater amounts During endodontic treatment, the Tinaz, et al., (2005) conducted a study of debris when the apical constriction and the shaping and cleaning procedure has the for the specific purpose of correlating debris apical foramen were intentionally enlarged. potential to contaminate the bloodstream extrusion and the apical limit of instrumen- Hence, instrumentation beyond the apical and the lymphatic system with bacteria tation. It compared the extrusion of debris foramen should be avoided in patients at high (Bender, et al., 1960; Baumgartner, et al., during manual and rotary instrumentation in risk for bacteremia, considering the greater 1976; Seymour, et al., 2000; Fouad, 2009). teeth that had intentionally enlarged apical risk of systemic spread of microorganisms Blood samples collected from patients constriction and apical foramen. Fifty-two (Debelian, et al., 1995; Seymour, et al., 2000; during and after endodontic treatment of teeth were divided into two groups with 26 Siqueira, Rôças, 2008; Hülsmann, Schäfer, teeth with pulp necrosis revealed the pres- specimens each, in accordance with the 2009; Baumann, Beer, 2011). ence of the same bacteria in both the root instrumentation technique used (manual canal system and the bloodstream (Heimdahl, instrumentation using K-files or rotary instru- Conclusion et al., 1990; Debelian, et al., 1995; Debelian, mentation using ProFile .04 taper series The difficulties in performing suitable et al., 1998; Savarrio, et al., 2005). Therefore, 29). The teeth were further divided into two shaping and cleaning of root canals, espe- microorganisms from the root canal can be subgroups, with intentional enlargement of cially in the final millimeters, has been proven carried to and then settle in locations distant the apical foramen by K-files No.15 and No. consistently (Paqué, et al., 2009; Paqué, et from their place of origin (Fouad, 2009). 30, 2 mm beyond the apical foramen. The al., 2010; Haapasalo, et al., 2005; Hulsmann, The extrusion of debris during shaping irrigating solution was 2.6% sodium hypo- et al., 2005; de Melo Ribeiro, et al., 2013; and cleaning of the root canal system has chlorite. No statistically significant differences Cruz, et al., 2014). Consequently, a wider

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variety of techniques have been recom- et al., 2010). Even considering the positive date, no randomized clinical trial has been mended to achieve more effective action results of these studies, there is no way to infer conducted with longitudinal follow-ups, from endodontic instruments (Olivieri, et al., that this procedure will have the same positive evaluating the success rates of endodontic 2014; Sant’Anna Júnior, et al., 2014) and biological responses in humans. treatments or retreatments where the apical irrigating solutions (van der Sluis, et al., 2007; According to the precepts of scientific limits of instrumentation were established for Brunson, et al., 2010). evidence-based , certain criteria the apical foramen or beyond. On the other There are occasions when endodontic must be respected and followed prior to any hand, high success rates have been reported infection extends beyond the limits of the interventions in humans. First, laboratory for apical limits of instrumentation established apical constriction — i.e., to the apical studies should be performed to construct a close to the apical constriction in controlled foramen or even beyond (extraradicular plausible hypothesis to be tested in vivo. Then clinical studies with robust samples and biofilm) (Noiri, et al., 2002; Chavez De Paz, in vivo animal studies should be performed appropriate inclusion and exclusion criteria 2007; Ricucci, Siqueira Jr, 2010). In these to observe any toxic or harmful potential of (Imura, et al., 2007; Ricucci, et al., 2011; situations, intentional foraminal enlargement the substances, drugs, or intervention. Ulti- Liang, et al., 2013). is designed to reduce the microbial load in mately, longitudinal, controlled clinical studies From a scientific perspective, it is obvious these areas to levels more favorable for repair are needed to observe the results and confirm that the impacts of intentional foraminal (Borlina, et al., 2010). possible advantages or disadvantages enlargement on the success of endodontic However, it must be pointed out that, to related to the previously considered hypoth- therapy should be evaluated. However, the date, there have been only animal studies esis (Seymour, et al., 2003; Miller, Forrest, methodology of these studies should be comparing the success rates between inten- 2009; Kwok, et al., 2012). even more carefully designed, insofar as the tional foraminal enlargement and conventional When it comes to the question of inten- literature reviewed in this paper reiterates that instrumentation limits (close to the apical tional foraminal enlargement, there is no this procedure poses both local and systemic constriction) (Holland, et al., 1979; Borlina, scientific evidence to support its use. To risks to the patient. EP

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