Journal of Conservative Dentistry
Home About us Editorial Board Instructions Submission Subscribe Advertise Contact e-Alerts Login 
Users Online: 1655
Print this page  Email this page Bookmark this page Small font sizeDefault font sizeIncrease font size

Table of Contents   
Year : 2023  |  Volume : 26  |  Issue : 1  |  Page : 3-11
Factors influencing the occurrence and progress of sodium hypochlorite accident: A narrative and update review

Department of Conservative Dentistry and Endodontics, Faculty of Dentistry, Manipal University College Malaysia, Jalan Batu Hampar, Bukit Baru, 75150 Melaka, Malaysia

Click here for correspondence address and email

Date of Submission22-Jul-2022
Date of Decision12-Aug-2022
Date of Acceptance23-Aug-2022
Date of Web Publication08-Dec-2022


Sodium hypochlorite (NaOCl) is one of the most commonly used irrigant because of its several advantages. However, it is highly cytotoxic and can lead to severe tissue damage. NaOCl accident occurs when it is extruded beyond root confines into periapical or periradicular tissues. It is an irrigant mishap which can be life threatening and/or cause residual or long term or permanent consequences with malpractice and medico-legal implications. There are many factors which can influence the occurrence and progress of NaOCl accident. These factors can be broadly categorized as patient (host)-, tooth-, operator-, and NaOCl-related factors. They can be further categorized as predisposing and extent factors. It is vital for a clinician to thoroughly understand and identify various influencing factors to prevent NaOCl accident with its associated consequences including any potential medico-legal issues. The purpose of this article is to provide a narrative review on various factors which predispose to the occurrence of NaOCl accident and influence its extent and/or outcome.

Keywords: Accident; complication; endodontics; extrusion; factor; irrigant; sodium hypochlorite

How to cite this article:
Vivekananda Pai A R. Factors influencing the occurrence and progress of sodium hypochlorite accident: A narrative and update review. J Conserv Dent 2023;26:3-11

How to cite this URL:
Vivekananda Pai A R. Factors influencing the occurrence and progress of sodium hypochlorite accident: A narrative and update review. J Conserv Dent [serial online] 2023 [cited 2023 Dec 7];26:3-11. Available from:

   Introduction Top

Sodium hypochlorite (NaOCl) has been the most popular and main irrigant in endodontics because of its advantageous properties. Therefore, it is widely preferred as a primary irrigant.[1],[2],[3] However, its cytotoxicity with damaging effects at cellular and tissue level has been a major concern.[4] NaOCl accident is an irrigant mishap with grave effects.[5] It mainly refers to the extrusion of NaOCl beyond the confines of root into periapical or periradicular tissues and/or tissue spaces of the oral cavity with subsequent consequences.[5],[6] From clinician or practitioner perspective, it also has malpractice and medico-legal implications.[7],[8] Although a recent study reported that the frequency of NaOCl extrusion and NaOCl accident were 0.89% and 0.18%, respectively, it is stated that many practitioners would have experienced it at least once in their career.[9],[10],[11] Therefore, it is very important for a clinician to identify the influencing factors and prevent NaOCl accident with its serious consequences including life threatening situations and potential medico-legal issues. The purpose of this article is to provide an overview on various factors influencing the occurrence and progress and/or outcome of NaOCl accident.

   Discussion Top

The factors influencing the occurrence and progress of NaOCl accident can be broadly categorised as patient (host)-, tooth-, operator-, and NaOCl-related factors. They can be further categorized as predisposing and extent factors. A predisposing factor mainly poses the risk for the occurrence of NaOCl accident, and it could be either a major or a minor one. A major factor directly poses the risk for NaOCl accident. Whereas a minor factor predisposes to the occurrence of a major factor and/or indirectly poses the risk for NaOCl accident. When NaOCl accident occurs, an extent factor mainly influences the progress or severity and/or outcome of NaOCl accident.

Patient (host)-related factors


Females are more prone to NaOCl accident than males.[10] This is attributed to lesser density and thickness of bone in females.[10] Furthermore, being more conscious about oral health and care than males, females are more among the patients undergoing endodontic treatment which can also increase the probability of NaOCl accident.[7],[12]


Although NaOCl accidents can occur in patients of any age group, younger patients are more vulnerable due to the presence of primary and/or young permanent tooth with wide or open apex.[13],[14] With aged patients, the risk of NaOCl extrusion into the maxillary sinus is higher as alveolar bone generally becomes thinner and root tips projecting into the sinus would have only a thin bone with overlying membrane as a barrier which offers minimal resistance to extrusion of NaOCl.[15],[16] Also, aged patients generally have a compromised medical status, reduced body resistance, and less repair potential. This can influence the extent of NaOCl accident in them compared to younger patients.[17],[18]

Position on the dental chair

Since NaOCl accident occurs when the apical pressure extruding NaOCl exceeds venous pressure in the surrounding vasculature and extruded NaOCl is infused into the vasculature, patient position on the dental chair can predispose to NaOCl accident because venous pressure changes with patient position on the dental chair.[5] In maxillary teeth with close proximity to sinus, patient's position on the dental chair may lead to stagnation of NaOCl along the thin bony wall of the maxillary sinus. The stagnated NaOCl can eventually seep through the overlying membrane into the sinus.[19] On the other hand, when NaOCl accident occurs, patient position on the dental chair can influence its progress or outcome, particularly in a maxillary tooth. Reclined or upright position may relieve some pressure from the head and reduce the extent of swelling.[6] But this may not be useful once swelling appears.[20] However, changing to a reclined position may still aid in better drainage from the sinus due to the anatomy of maxillary sinus and its openings.[21]

Degree of alveolar bone calcification

Highly calcified/hyperplastic bone with reduced marrow space/volume offers more resistance to infusion of fluids.[5] Since cortical bone is more calcified and is not affected by NaOCl even at a concentration of 5.25%, a dense or thicker cortical bone and/or alveolar bone with less marrow space would exhibit a low-compliance behaviour and reduce the risk for NaOCl accident.[4],[11]

Dental treatment

Patients with orthodontic treatment involving root movement, particularly in an anterior tooth, can pose a risk for NaOCl accident because the root movement can lead to apical bony fenestration and/or apical root resorption which predispose to NaOCl accident.[22]

Medical status and/or treatment

The extent of NaOCl accident with associated complications would be more in an immunocompromised patient when compared with a patient having normal medical status.[10] NaOCl accident in an immunocompromised patient can be life threatening due to extensive systemic involvement and lack of response to any form of intervention including hospitalization.[23] Bisphosphonate therapy is generally recommended in postmenopausal females with osteoporosis and in cancer patients. However, it can predispose to infection with osteonecrosis. Therefore, it can influence the severity of NaOCl accident in such patients. But this risk depends on whether the bisphosphonate is administered orally or systemically. Recent case reports have shown uneventful outcome following NaOCl accident in patients with oral bisphosphonate therapy.[24],[25] Mentally challenged patients may fail to communicate the symptoms of NaOCl accident to immediately alert the clinician. This can also influence the extent of NaOCl accident.[26]


Other host factors such as proximity of vital structures and specific location of venous vasculature with associated tissues can also influence the manifestation and extent of NaOCl accident.[5],[17],[27]

Tooth-related factors

Type of teeth

Although NaOCl accidents are mostly reported with adult permanent teeth, a young permanent tooth is also prone to NaOCl accident due to shorter and immature root with open apex.[18] A primary tooth poses a similar risk as more emphasis is placed on irrigation to compensate for the limited canal shaping due to anatomical reasons related to complicated, curved, and tortuous root canals and/or because of immature or open apex[13],[27] or shorter root with wide apex due to physiologic root resorption.[14],[17] Cases of NaOCl accident in primary teeth,[13],[27],[28],[29],[30],[31],[32] including in a retained one,[33] have been reported.

Group of teeth

Maxillary teeth are more susceptible to NaOCl accident than the mandibular teeth. The higher risk with maxillary teeth is due to the thinness of cortical bone surrounding the buccal roots of maxillary teeth, apical root fenestration, proximity to maxillary sinus, and fast spreading of NaOCl into the surrounding soft tissues.[5],[10],[22],[34] Among the maxillary teeth, premolar and molar teeth have a relatively higher risk compared to anterior teeth. This is because maxillary posteriors have greater prevalence of apical root fenestration and are close to maxillary sinus.[10],[22] Among the mandibular teeth, posterior teeth[7],[14],[35],[36],[37],[38],[39],[40],[41] have been reported with more NaOCl accident than anterior teeth[42],[43],[44],[45],[46] despite the former being less susceptible to such an accident due to their anatomical position within the mandible.[10],[17]

Size and morphology of teeth

Smaller teeth such as mandibular incisors and teeth with danger zones or constricted cervical anatomy such as mandibular premolars are prone to iatrogenic errors such as poorly designed access preparation and perforation which predispose to NaOCl accident.[17],[43],[47]

Anatomical position of teeth

The position of tooth in relation to alveolar bone is a risk factor for NaOCl accident. Since the buccal roots of maxillary premolar and molar teeth are close to overlying bone with thin cortical plate, these teeth are prone to NaOCl accident.[10],[17] Mandibular teeth, particularly premolars and molars, are at a lesser risk because they are encased in a denser cortical plate and their apices are more centrally located within the body of the mandible.[10],[17]

Proximity to maxillary sinus

Cases of NaOCl accident in maxillary sinus have been reported.[16],[19],[21],[35],[48],[49],[50],[51] A tooth closer to maxillary sinus has a higher risk for NaOCl accident because of thinner bone around its root apex.[15],[16],[51] However, since maxillary sinus is not an enclosed space, extruded NaOCl may get evacuated through the nostrils with limited duration of tissue contact in the sinus. This influences the manifestation, extent, and outcome when compared with extrusion of NaOCl into periradicular tissues.[16],[19],[21],[48],[49],[50],[52]

Presence of root defects

A widened apical foramen[33] or root perforation due to physiologic or pathologic resorption,[31],[45],[53],[54] or root fenestration,[24],[25],[55],[56] or root fracture[57] increases the potential for NaOCl accident.[5],[38],[42] A recent study by Souza et al.[22] confirmed that the presence of a root fenestration is a significant risk factor for NaOCl accident due to direct communication of the apical foramen with the overlying mucosa or tissue spaces. This risk is greater in maxillary premolars as they have higher prevalence of root fenestration.

Root canal system

The presence of multiple roots and/or canals can increase the probability of NaOCl accident. Also, a tooth with complex root canal system has higher chances of iatrogenic errors such as ledging and perforation which predisposes to NaOCl accident.[43]

Type of root apex

An immature or open apex[18],[27],[28] or a widened apex due to resorption[31],[33],[45],[53],[54] or faulty endodontic treatment[23],[58],[59] increases the risk for NaOCl accident when compared to a matured or closed apex.

Apical patency

A patent apical foramen increases the potential for NaOCl accident.[49] Extrusion of NaOCl was found significantly higher when filing was taken to the apical foramen as it leads to inadvertent widening of apical constriction.[38],[49] Greater the size of apical patency file, higher the risk for NaOCl accident.[60] The presence of an apical plug minimizes this risk.[61]

Pulpal and periapical status

Most of the reported cases have occurred in nonvital teeth with and without a periapical lesion when compared to vital teeth or teeth with unknown pulpal status and no periapical lesion.[10],[34],[52] Although pulp extirpation mostly precedes major part of the irrigation step, any vital pulp tissue or its remnants in the root canal including lateral canals can resist extrusion of NaOCl.[60],[61],[62] Furthermore, when NaOCl comes in contact with any tissue remnants or organic material in the canal, it gets disintegrated into nontoxic products (Na+ and Cl).[35] On the contrary, a root canal of a nonvital or pulpless tooth may act as a dead space and a pathway for easy extrusion of NaOCl.[60],[62] Moreover, it would need more amount of NaOCl for effective canal disinfection, thus increasing the risk for NaOCl accident when compared with a tooth having vital pulp.[62]

Like vital pulp tissue, intact periapical tissues might provide a natural barrier, offer significant back pressure, and react with low compliance to resist NaOCl extrusion.[11],[62] The back pressure offered by periapical tissues depends on their anatomy and compliance level.[10],[11],[34],[63] On the other hand, a periapical lesion may facilitate NaOCl extrusion due to negative tissue pressure.[38] Once NaOCl is extruded, the periapical lesion can act as a container for extruded NaOCl and prevents its drainage back through the canal and allows it to leach into adjacent tissues or increases the chance of direct contact between NaOCl and the surrounding tissues.[26],[60] However, a periapical lesion may minimize the potential for NaOCl accident because it can dissipate the pressure which causes NaOCl extrusion and prevent intravenous infusion of extruded NaOCl due to lack of blood supply.[5],[10] Moreover, a periapical lesion entirely surrounded by cortical bone can minimize NaOCl extrusion because the cortical bone is resistant to degrading effects of NaOCl and there is low compliance to apical irrigation force due to significant back pressure from the surrounding tissues.[11] However, a periapical lesion leads to bone resorption which eventually causes a bony fenestration or dehiscence and communication with a fascial space.[10] This creates high compliance to apical irrigation pressure due to lack of adequate back pressure from surrounding tissues with potential for significant extrusion of NaOCl.[11] Therefore, a nonvital or pulpless tooth with a large or extensive periapical lesion is a significant predisposing factor for NaOCl accident.[5],[10],[11],[58],[64],[65]

Presence of sinus tract

Although cases of NaOCl accident in the presence of a sinus tact have been reported,[45],[64] presence of a sinus tract would provide a pathway into the oral cavity rather than into a tissue space and can minimize the risk for NaOCl accident.[10] However, based on the compliance theory, a sinus tract with an opening can increase the compliance of the periapical lesion due to reduced or lack of back-pressure.[11],[63] This can be a concern because more NaOCl would get extruded into oral cavity, if not into the periradicular tissues, through the sinus tract and can cause damage to the oral mucosa.

Periodontal status

Periodontal conditions, including endodontic-periodontal lesions, can be a potential risk factor as there could be patent lateral or accessory canals which can act as an additional pathway for NaOCl extrusion.[66],[67]

Operator-related factors


Gender of the operator plays a role in the pressure exerted on the dental syringes. Although scientific evidence is limited, female operators when compared with male operators are shown to deliver NaOCl with lesser pressure and lower flow rate which reduce the risk for NaOCl accident.[68]

Type of operator

The risk for NaOCl accidents could be higher with dental graduates or postgraduates and general practitioners when compared with endodontists due to lesser extent of awareness, knowledge, or experience. However, this could be overshadowed by the fact that endodontists more often treat posterior teeth, which have relatively higher risk for NaOCl accident than anterior teeth, when compared with the dental graduates or postgraduates and general practitioners.[10],[52] Moreover, such accidents by the latter may go more often unreported when compared with the former.[67]


Although experience of the operator was negatively correlated to parameters related to NaOCl accident, it can be presumed that more the experience of the operator, the lesser the risk for NaOCl accident. An inexperienced operator may lack confidence or awareness on factors influencing NaOCl irrigation which increases the risk for NaOCl accident.[68]

Clinical skill, reaction time and speed of referral

Faster the operator diagnoses and manages as per the protocol or refers a NaOCl accident case, lesser would be its extent.[45] Poor management or delayed referral can lead to life threatening situation[23] or airway obstruction[37],[44] or carry the risk of residual damage or long-term effects[69] such as neurological deficit,[51],[58],[65],[70] ocular damage,[51] hypertrophied or excessive granulation tissue and fibrosis,[19],[71],[72] mucosal or facial tissue scarring,[43],[56] facial atrophy,[70],[73] facial discoloration,[74] and cosmetic deformity.[35],[40],[72],[75]

Method of anesthesia

Local anesthesia may delay the early diagnosis of an irrigant related mishap.[76] The potential for NaOCl accident to go unnoticed is even higher when a patient is under general anesthesia because of factors such as surgical draping of patient's face and lack of patient response to alert clinician about immediate signs and symptoms of NaOCl accident.[27],[28] This can affect early identification and management and influence the extent of NaOCl accident.[26],[27]

Site of access preparation and number of scheduled visits

Preparing access at wrong site of tooth has higher potential for iatrogenic errors such as perforation which predispose to NaOCl accident. However, in an anterior tooth, unconventional access prepared through incisal or labial surface could reduce the risk of perforation and NaOCl accident when compared with a traditional access prepared through lingual or palatal surface.[43] It is also reported that the probability of NaOCl accident may increase with increase in the number of visits.[9]

Motion of root canal instruments

The filing action of the instrument can act as a piston or plunger in a root canal and generate hydrostatic pressure to push NaOCl into periapical tissues.[11],[21],[26],[61] However, the risk for NaOCl accident would depend on the amount of NaOCl present in the canal at the time of filing and patency of apical foramen.[49],[60]

Apical canal diameter or width

The risk of NaOCl accident becomes higher as apical canal is enlarged to a file size no. 30 or greater.[60],[62],[77] Although extrusion of NaOCl could occur without apical enlargement, the risk of extrusion increases once canal is enlarged even to a smaller extent and when NaOCl is deposited at the canal orifice without any pressure.[60] The apical preparation with a lesser size showed significantly lower frequency of extrusion when compared to one with a greater size. The apical preparation size also significantly influenced the differences in the frequency of extrusion by various irrigation methods. When the apical preparation size was smaller, there were significant differences in the frequency of extrusion shown by various irrigation methods which were based on syringe and needle (positive pressure), sonic and ultrasonic activation, and negative pressure techniques. The negative pressure-based method showed less risk and lowest frequency of extrusion. However, when the apical preparation size was greater, the differences in the frequency of extrusion among these methods became insignificant with negative pressure-based method also showing higher frequency of extrusion.[77],[78]

Selection of irrigation technique

Employing syringe or manual, manual-dynamic, laser-activated, and positive pressure irrigation techniques have higher risk for NaOCl accident when compared with sonic or ultrasonic activation or negative pressure irrigation techniques.[11],[34],[77],[78],[79],[80],[81] It is interesting to know that laser activation is capable of creating pressure waves and fluid movement within the root canal that is sufficient enough to extrude NaOCl, particularly when the apical foramen is larger and the laser is used in a pulsed mode.[79] However, a recent study reported that laser assisted irrigation caused less extrusion compared to conventional needle irrigation.[82] The irrigation technique can influence both the frequency and extent of NaOCl extrusion. Among the various irrigation techniques such as syringe and needle (positive pressure), sonic and ultrasonic activation, and negative pressure techniques, the syringe and needle technique showed the most frequency and extent of NaOCl extrusion irrespective of the apical preparation size. With the remaining techniques, the frequency and extent of NaOCl extrusion were less but varied depending on the apical preparation size. The negative pressure technique showed the most favourable results considering frequency and extent of extrusion and the apical preparation size.[77]

Selection of irrigation syringe and needle

Although the size of irrigation needle in NaOCl accidents has varied from 16G to 30G,[25],[34],[68],[83] selecting an improper or a larger capacity syringe and/or wide-bored, nonbeveled, and open-ended or end lumen irrigation needle predispose to NaOCl accident.[5],[34],[68],[79]

Level of positioning and amount of binding of the irrigation needle

Positioning the irrigation needle apically or deeper into the canal or closer to working length and tightly binding (i.e., wedging or locking) the needle in the canal pose a greater risk for NaOCl accident.[34],[42] Needle binding is an important factor as no needle design, including safer side vented needle, could prevent high apical irrigation pressure in the presence of binding.[84] NaOCl accident with closed-ended or side vented needle due to needle binding have also been reported.[16],[45],[66]

Irrigation force applied on the syringe

Higher irrigation force applied on the plunger of the syringe predisposes to NaOCl accident.[11],[34] Irrigation force applied on the plunger of the syringe depends on gender of the operator, the part of the hand or the finger used for applying the force, needle diameter, and syringe size. Irrigation force would be higher with a male operator, use of thumb for applying the force, smaller diameter needle, and larger capacity syringe.[34],[68]

Apical irrigation pressure

Higher apical irrigation pressure increases the risk of NaOCl accident.[68] The apical pressure depends on size of apical preparation, irrigation force applied on the syringe, irrigant flow rate, and type of needle and irrigation technique. The irrigation pressure becomes higher when a canal is enlarged to a size 30 and larger, irrigant is delivered with higher or inappropriate force, irrigant flow rate is higher, an open-ended needle or a needle without safety features is used, and a positive-pressure irrigation technique is employed.[11],[34],[80],[81],[85] However, apical irrigation pressure leads to NaOCl accident only when it exceeds the threshold of back pressure offered by surrounding tissues depending on their anatomy and compliance level.[11],[34],[63],[80],[81]

Irrigant flow rate

Irrigant flow rate is influenced by gender of the operator, irrigation technique, irrigation force and pressure, needle design, needle diameter, and syringe capacity.[34],[68],[85] Higher flow rate of NaOCl increases the potential for its extrusion.[80],[81] Irrigant flow rate is higher with a male operator, positive pressure technique, higher irrigation force, use of an open-ended needle, use of a needle with a larger diameter, and use of a larger capacity syringe which has a tendency to deliver larger volume of NaOCl even with a small movement of plunger.[68] Although irrigant flow rate is lower when a needle with a smaller diameter is used, the risk for NaOCl accident is still higher because such a needle offers more resistance to delivery of NaOCl and has an increased tendency to get blocked with sodium chlorite crystals.[38],[68] Thus, a needle with a smaller diameter needs higher pressure on the syringe plunger, which leads to delivery of NaOCl at a higher velocity, increasing the risk for NaOCl accident.[38],[68]

Iatrogenic errors

Any iatrogenic error such as carrying out endodontic treatment without initial or preoperative radiograph, insufficient or poorly designed access opening, faulty working length, copious or forced irrigation, inadvertent or accidental irrigation beyond apical foramen, intentional irrigation through the apical foramen for periapical disinfection, over prepared or over instrumented root apex, over insertion of irrigation needle beyond apical foramen, destruction of apical constriction, apical or lateral root perforation, use of compressed air, and faulty nonsurgical or surgical treatment increase the risk for NaOCl accident.[10],[28],[34],[42],[52],[86]

Sodium hypochlorite-related factors

Chemical composition

The manifestation and extent of NaOCl accident is attributed to the chemical composition of NaOCl with its properties such as high cytotoxicity due to causticity, hyperosmolarity, proteolytic effect, and oxidant action.[5]

Physical form

Physical form of NaOCl can influence its extrusion.[87] NaOCl in gel form has lesser tendency for periapical extrusion when compared with NaOCl in solution form.[88] NaOCl gel showed significantly less extrusion compared to NaOCl solution when the apical diameter was ≤2.5 mm.[89] The risk of extrusion can be further reduced, especially in case of larger apical diameter or wider apex, if NaOCl gel could be coated or carried into the canal rather than injected.


Most of the NaOCl accidents have been reported with a concentration ranging from 2.5% to 5.25%.[10],[34],[52] Since NaOCl at a concentration ≥0.25% becomes significantly toxic to tissues, concentration as low as 1% has also led to NaOCl accident.[28],[31],[40],[45],[90],[91] Although studies are lacking, concentration of NaOCl with its available chlorine can influence the extent of NaOCl accident because cytotoxicity of NaOCl is directly proportional to its concentration.[3],[10],[11],[27],[34],[52],[90]


The volume of extruded NaOCl can influence the occurrence and extent of NaOCl accident.[87],[90] The volume of NaOCl used at the time of accident has been reported to range from 0.1 to 30 mL.[34],[67] Studies are lacking on the minimum volume of extruded NaOCl that can lead to tissue damage and on the relationship between volume of extruded NaOCl and extent of NaOCl accident.[27] However, since extrusion of even a small amount of NaOCl can cause severe tissue damage, volume of extruded NaOCl can influence the extent of NaOCl accident.[10],[11],[34],[52],[69]


The pH of NaOCl can influence the extent of NaOCl accident. Unbuffered NaOCl with higher pH (12.9) is more cytotoxic and can lead to greater tissue damage when compared with buffered NaOCl.[75]


The use of preheated NaOCl has been reported with NaOCl accident.[49] Although temperature of NaOCl has been attributed as a factor, there is no evidence to indicate that temperature aggravates the damaging effect of NaOCl.[87],[90] Moreover, temperature of NaOCl may not significantly influence the extent of NaOCl accident as the temperature equilibrium is attained rapidly.[3]


Nature and duration of NaOCl contact with tissues can influence the extent of NaOCl accident.[87] Provided the time of contact with NaOCl is minimal, the extent of damage on contact with the tissue surface is different compared to contact within the tissues.[21] The spatial location of NaOCl introduction and speed of NaOCl spread and its elimination would also influence the extent of NaOCl accident.[17],[90]

The discussed factors are summarized in [Table 1], [Table 2], [Table 3], [Table 4]. When NaOCl accident occurs under the influence of these factors, its management includes immediate measures in the form of stopping NaOCl irrigation, informing the patient, staying calm and composed, immediately aspirating and/or diluting the extruded NaOCl, allowing bleeding through the root canal, controlling swelling with ice packs in the initial 24 h, leaving the tooth open, controlling pain with local anesthetics and analgesics, prescribing antibiotics to prevent secondary infection, and prescribing medications such as steroids and antihistamines for controlling symptoms.[52],[91],[92],[93] In case of compromised airway or other complications, patient must be immediately referred to oral and maxillofacial surgery unit or hospitalized for emergency or intensive care.[33],[40] After 24 h, warm compresses and warm saline rinses must be advised.[6],[47],[72],[92],[93] Incision and drainage or surgical decompression can be considered when fascial spaces are involved.[20],[33],[37],[53],[72] Surgical debridement is recommended in case of soft or hard tissue necrosis.[26],[33],[40],[75],[92] Lasers can be considered for adjunctive therapy to facilitate healing.[24],[41],[46],[94] Tooth left open should be closed, and the patient must be regularly reviewed.[93] Subsequently, RCT can be completed using irrigants preferably other than NaOCl.[10],[27],[54],[93] In case of persistent pain and/or poor prognosis, extraction of the involved tooth could be the last resort.[33],[54],[73],[86] Referral to a specialist would be required for long-term effects such as neurological and ophthalmological complications.[93] Cosmetic surgical procedures can be considered for correcting any facial deformity subsequent to healing of damaged tissues.[40],[73],[93]
Table 1: Patient (host)-related factors influencing the occurrence and extent of sodium hypochlorite accident

Click here to view
Table 2: Tooth-related factors influencing the occurrence and extent of sodium hypochlorite accident

Click here to view
Table 3: Operator-related factors influencing the occurrence and extent of sodium hypochlorite accident

Click here to view
Table 4: Sodium hypochlorite-related factors influencing the occurrence and extent of sodium hypochlorite accident

Click here to view

   Conclusion Top

Although NaOCl accident is mainly an iatrogenic mishap, operator-related factors along with various factors related to patient (host), tooth, and NaOCl play an important role in influencing the occurrence and extent of NaOCl accident. A clinician must ensure thorough pre-endodontic evaluation of the patient to identify the predisposing factors and avoid any iatrogenic error during the endodontic treatment which can predispose to NaOCl accident. This would assist a clinician to prevent NaOCl accident with its consequences including any potential medico-legal issues.


The author thanks Dr. Vinita V. Pai for her valuable assistance during manuscript preparation and verification.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Kandaswamy D, Venkateshbabu N. Root canal irrigants. J Conserv Dent 2010;13:256-64.  Back to cited text no. 1
[PUBMED]  [Full text]  
Gopikrishna V, Pare S, Pradeep Kumar A, Lakshmi Narayanan L. Irrigation protocol among endodontic faculty and post-graduate students in dental colleges of India: A survey. J Conserv Dent 2013;16:394-8.  Back to cited text no. 2
[PUBMED]  [Full text]  
Zehnder M. Root canal irrigants. J Endod 2006;32:389-98.  Back to cited text no. 3
Kerbl FM, DeVilliers P, Litaker M, Eleazer PD. Physical effects of sodium hypochlorite on bone: An ex vivo study. J Endod 2012;38:357-9.  Back to cited text no. 4
Zhu WC, Gyamfi J, Niu LN, Schoeffel GJ, Liu SY, Santarcangelo F, et al. Anatomy of sodium hypochlorite accidents involving facial ecchymosis – A review. J Dent 2013;41:935-48.  Back to cited text no. 5
Becker GL, Cohen S, Borer R. The sequelae of accidentally injecting sodium hypochlorite beyond the root apex. Report of a case. Oral Surg Oral Med Oral Pathol 1974;38:633-8.  Back to cited text no. 6
Givol N, Rosen E, Bjørndal L, Taschieri S, Ofec R, Tsesis I. Medico-legal aspects of altered sensation following endodontic treatment: A retrospective case series. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;112:126-31.  Back to cited text no. 7
Swanljung O, Vehkalahti MM. Root canal irrigants and medicaments in endodontic malpractice cases: A nationwide longitudinal observation. J Endod 2018;44:559-64.  Back to cited text no. 8
Özdemir O, Hazar E, Koçak S, Sağlam BC, Koçak MM. The frequency of sodium hypochlorite extrusion during root canal treatment: An observational clinical study. Aust Dent J 2022. doi: 10.1111/adj.12924. Epub ahead of print. PMID: 35707880.  Back to cited text no. 9
Kleier DJ, Averbach RE, Mehdipour O. The sodium hypochlorite accident: Experience of diplomates of the American Board of Endodontics. J Endod 2008;34:1346-50.  Back to cited text no. 10
Psimma Z, Boutsioukis C. A critical view on sodium hypochlorite accidents. ENDO EPT 2019;13:165-75.  Back to cited text no. 11
Umanah A, Osagbemiro B, Arigbede A. Pattern of demand for endodontic treatment by adult patients in Port-Harcourt, South-South Nigeria. J West Afr Coll Surg 2012;2:12-23.  Back to cited text no. 12
Hong SY, Kim JW, Kim JY, Mah YJ, Ahn BD. Complications of sodium hypochlorite during re-endodontic treatment of maxillary primary central incisor: A case report. J Korean Acad Pediatr Dent 2012;39:186-91.  Back to cited text no. 13
Goswami M, Chhabra N, Kumar G, Verma M, Chhabra A. Sodium hypochlorite dental accidents. Paediatr Int Child Health 2014;34:66-9.  Back to cited text no. 14
Hauman CH, Chandler NP, Tong DC. Endodontic implications of the maxillary sinus: A review. Int Endod J 2002;35:127-41.  Back to cited text no. 15
Zairi A, Lambrianidis T. Accidental extrusion of sodium hypochlorite into the maxillary sinus. Quintessence Int 2008;39:745-8.  Back to cited text no. 16
Hargreaves KM, Cohen S, Berman LH. Cohen's Pathways of the Pulp. 11th ed. St. Louis, MO: Mosby Elsevier; 2011.  Back to cited text no. 17
Poommak S. Management of endodontic patient associated with sodium hypochlorite accident in Chaiyaphum hospital: A case report. J Health Sci 2014;23:564-74.  Back to cited text no. 18
Sleiman P. Irrigation for the root canal and nothing but the root canal. Roots 2012;4:32-3.  Back to cited text no. 19
Behrents KT, Speer ML, Noujeim M. Sodium hypochlorite accident with evaluation by cone beam computed tomography. Int Endod J 2012;45:492-8.  Back to cited text no. 20
Ehrich DG, Brian JD Jr., Walker WA. Sodium hypochlorite accident: Inadvertent injection into the maxillary sinus. J Endod 1993;19:180-2.  Back to cited text no. 21
Souza EM, Campos MG, Rosas Aguilar R. Mapping the periapex anatomical pattern of teeth involved in sodium hypochlorite accidents: A cross-sectional quasi-experimental study. Int Endod J 2021;54:1212-20.  Back to cited text no. 22
da Fonseca Wastner B, de Souza Lessa M, Sassi LM, Pianovski MA. Life-threatening reaction of a pediatric cancer patient to sodium hypochlorite. Res Soc Dev 2021;10:1-6.  Back to cited text no. 23
Magallon HC, Alonso DH, Zaragoza DE, Valdiosera FE. Low-level laser therapy as a coadjuvant in sodium hypochlorite extrusion management. J Dent Oral Sci 2020;2:1-10.  Back to cited text no. 24
Coaguila-Llerena H, Denegri-Hacking A, Lucano-Tinoco L, Mendiola-Aquino C, Faria G. Accidental extrusion of sodium hypochlorite in a patient taking alendronate: A case report with an 8-year follow-up. J Endod 2021;47:1947-52.  Back to cited text no. 25
Lee J, Lorenzo D, Rawlins T, Cardo VA Jr. Sodium hypochlorite extrusion: An atypical case of massive soft tissue necrosis. J Oral Maxillofac Surg 2011;69:1776-81.  Back to cited text no. 26
Klein U, Kleier DJ. Sodium hypochlorite accident in a pediatric patient. Pediatr Dent 2013;35:534-8.  Back to cited text no. 27
Wright KJ, Derkson GD, Riding KH. Tissue-space emphysema, tissue necrosis, and infection following use of compressed air during pulp therapy: Case report. Pediatr Dent 1991;13:110-3.  Back to cited text no. 28
Greene AE, Roosevelt GE, Grubenhoff JA, Klein U. Little boy black and blue. Pediatr Emerg Care 2011;27:758-9.  Back to cited text no. 29
Chaugule VB, Panse AM, Gawali PN. Adverse reaction of sodium hypochlorite during endodontic treatment of primary teeth. Int J Clin Pediatr Dent 2015;8:153-6.  Back to cited text no. 30
Kim M, Kim J, Lim S. Accidental extrusion of sodium hypochlorite during endodontic treatment in a primary tooth. J Korean Acad Pediatr Dent 2015;42:264-9.  Back to cited text no. 31
Santos ML, Silva H, Afonso A, Patraquim C. Hypochlorite accident: Fortunately a rare case in paediatric patients. BMJ Case Rep 2021;14:e233206.  Back to cited text no. 32
Mehra P, Clancy C, Wu J. Formation of a facial hematoma during endodontic therapy. J Am Dent Assoc 2000;131:67-71.  Back to cited text no. 33
Boutsioukis C, Psimma Z, van der Sluis LW. Factors affecting irrigant extrusion during root canal irrigation: A systematic review. Int Endod J 2013;46:599-618.  Back to cited text no. 34
Becking AG. Complications in the use of sodium hypochlorite during endodontic treatment. Report of three cases. Oral Surg Oral Med Oral Pathol 1991;71:346-8.  Back to cited text no. 35
Gernhardt CR, Eppendorf K, Kozlowski A, Brandt M. Toxicity of concentrated sodium hypochlorite used as an endodontic irrigant. Int Endod J 2004;37:272-80.  Back to cited text no. 36
Bowden JR, Ethunandan M, Brennan PA. Life-threatening airway obstruction secondary to hypochlorite extrusion during root canal treatment. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006;101:402-4.  Back to cited text no. 37
Hülsmann M, Rödig T, Nordmeyer S. Complications during root canal irrigation. Endod Topics 2009;16:27-63.  Back to cited text no. 38
Wang SH, Chung MP, Cheng JC, Chen CP, Shieh YS. Sodium hypochlorite accidentally extruded beyond the apical foramen. J Med Sci 2010;30:61-5.  Back to cited text no. 39
Chaudhry H, Wildan TM, Popat S, Anand R, Dhariwal D. Before you reach for the bleach. Br Dent J 2011;210:157-60.  Back to cited text no. 40
Yamamoto-Silva FP, Silva LR, de Lima KL, Silva MA, Estrela C, de Freitas Silva BS. Low-level laser therapy as adjunctive treatment for a sodium hypochlorite accident: A case report. Gen Dent 2019;67:63-6.  Back to cited text no. 41
Hülsmann M, Hahn W. Complications during root canal irrigation-literature review and case reports. Int Endod J 2000;33:186-93.  Back to cited text no. 42
Doherty MA, Thomas MB, Dummer PM. Sodium hypochlorite accident – A complication of poor access cavity design. Dent Update 2009;36:7-12.  Back to cited text no. 43
Al-Sebaei MO, Halabi OA, El-Hakim IE. Sodium hypochlorite accident resulting in life-threatening airway obstruction during root canal treatment: A case report. Clin Cosmet Investig Dent 2015;7:41-4.  Back to cited text no. 44
Patel E, Gangadin M. Managing sodium hypochlorite accidents: The reality of toxicity. S Afr Dent J 2017;72:271-4.  Back to cited text no. 45
Piazza B, Vivan RR, Alcalde MP, Duarte MA, de Andrade FB, Guimarães BM, et al. Laser therapy as an adjunct in the treatment of sodium hypochlorite extrusion through a root perforation: A case report. Gen Dent 2018;66:69-72.  Back to cited text no. 46
Balto H, Al-Nazhan S. Accidental injection of sodium hypochlorite beyond the root apex. Saudi Dent J 2002;14:36-8.  Back to cited text no. 47
Kavanagh CP, Taylor J. Inadvertent injection of sodium hypochlorite into the maxillary sinus. Br Dent J 1998;185:336-7.  Back to cited text no. 48
Bengs B. Irrigation incident during treatment of a maxillary premolar: A case report. Endodontie 2013;22:135-42.  Back to cited text no. 49
Laverty DP. A case report of accidental extrusion of sodium hypochlorite into the maxillary sinus during endodontic retreatment and review of current prevention and management. J Res Dent 2014;2:96-100.  Back to cited text no. 50
  [Full text]  
Costa T, Ferreira E, Antunes L, Dinis PB. Antral bony wall erosion, trigeminal nerve injury, and enophthalmos after root canal surgery. Allergy Rhinol (Providence) 2016;7:99-101.  Back to cited text no. 51
Guivarc'h M, Ordioni U, Ahmed HM, Cohen S, Catherine JH, Bukiet F. Sodium hypochlorite accident: A systematic review. J Endod 2017;43:16-24.  Back to cited text no. 52
Tegginmani VS, Chawla VL, Kahate MM, Jain VS. Hypochlorite accident – A case report. Endodontology 2011;23:89-94.  Back to cited text no. 53
  [Full text]  
Bosch-Aranda ML, Canalda-Sahli C, Figueiredo R, Gay-Escoda C. Complications following an accidental sodium hypochlorite extrusion: A report of two cases. J Clin Exp Dent 2012;4:e194-8.  Back to cited text no. 54
Başer Can ED, Karapınar Kazandağ M, Kaptan RF. Inadvertent apical extrusion of sodium hypochlorite with evaluation by dental volumetric tomography. Case Rep Dent 2015;2015:247547. doi: 10.1155/2015/247547.  Back to cited text no. 55
Al Fouzan K. Neurological complication and facial skin scarring following inadvertent extrusion of sodium hypochlorite and calcium hydroxide during root canal treatment-report of a case. ENDO 2016;10:45-9.  Back to cited text no. 56
Braitt AH, Lins SM, Vieira PD, Braitt GR, Martin AS, Bueno CE. Accidental extrusion of hypochlorite during endodontic treatment of tooth with fractured root. Rev Assoc Paul Cir Dent 2010;64:55-8.  Back to cited text no. 57
Pelka M, Petschelt A. Permanent mimic musculature and nerve damage caused by sodium hypochlorite: A case report. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;106:e80-3.  Back to cited text no. 58
Lirios MR, Batista RT, Viña MD. Accident by diffusion of sodium hypochlorite during endodontic treatment. Acta Odontol 2010;7:50-5.  Back to cited text no. 59
Camoes IC, Salles MR, Fernando MV, Freitas LF, Gomes CC. Relationship between the size of patency file and apical extrusion of sodium hypochlorite. Indian J Dent Res 2009;20:426-30.  Back to cited text no. 60
[PUBMED]  [Full text]  
Brown DC, Moore BK, Brown CE Jr., Newton CW. An in vitro study of apical extrusion of sodium hypochlorite during endodontic canal preparation. J Endod 1995;21:587-91.  Back to cited text no. 61
Salzgeber RM, Brilliant JD. An in vivo evaluation of the penetration of an irrigating solution in root canals. J Endod 1977;3:394-8.  Back to cited text no. 62
Psimma Z, Boutsioukis C, Vasiliadis L, Kastrinakis E. A new method for real-time quantification of irrigant extrusion during root canal irrigation ex vivo. Int Endod J 2013;46:619-31.  Back to cited text no. 63
Witton R, Henthorn K, Ethunandan M, Harmer S, Brennan PA. Neurological complications following extrusion of sodium hypochlorite solution during root canal treatment. Int Endod J 2005;38:843-8.  Back to cited text no. 64
Perotti S, Bin P, Cecchi R. Hypochlorite accident during wndodontic therapy with nerve damage – A case report. Acta Biomed 2018;89:104-8.  Back to cited text no. 65
Pereira KF, de Souza Mello ML, Arashiro FN, Estrela C. Application of low-level laser as auxiliary therapeutic of swelling areas caused by apical accidental extrusion of sodium hypochlorite: Case report. Rev Odontol Bras Central 2014;23:202-6.  Back to cited text no. 66
Alves FR, Marceliano-Alves MF, Souza AC, Campello AF. Mucosal fenestration after 2% chlorhexidine extrusion used in substitution of sodium hypochlorite: A case report. Eur J Dent 2020;14:511-6.  Back to cited text no. 67
Boutsioukis C, Lambrianidis T, Kastrinakis E, Bekiaroglou P. Measurement of pressure and flow rates during irrigation of a root canal ex vivo with three endodontic needles. Int Endod J 2007;40:504-13.  Back to cited text no. 68
Abramson A, Sabag E, Nahlieli O. Surgical approach to a severe case of sodium hypochlorite accident: A case report and review of the literature. Quintessence Int 2021;52:806-10.  Back to cited text no. 69
Nichols L. Hypochlorite injuries. Br Dent J 2020;229:761.  Back to cited text no. 70
Juárez RP, Lucas ON. Complications caused by accidental infiltration with a sodium hypochlorite solution. Rev Assoc Dent Mex 2001;58:173-6.  Back to cited text no. 71
Lam TS, Wong OF, Tang SY. A case report of sodium hypochlorite accident. Hong Kong J Emerg Med 2010;17:173-6.  Back to cited text no. 72
Markose G, Cotter CJ, Hislop WS. Facial atrophy following accidental subcutaneous extrusion of sodium hypochlorite. Br Dent J 2009;206:263-4.  Back to cited text no. 73
Faras F, Abo-Alhassan F, Sadeq A, Burezq H. Complication of improper management of sodium hypochlorite accident during root canal treatment. J Int Soc Prev Community Dent 2016;6:493-6.  Back to cited text no. 74
Gatot A, Arbelle J, Leiberman A, Yanai-Inbar I. Effects of sodium hypochlorite on soft tissues after its inadvertent injection beyond the root apex. J Endod 1991;17:573-4.  Back to cited text no. 75
Patterson CJ, McLundie AC. Apical penetration by a root canal irrigant: A case report. Int Endod J 1989;22:197-9.  Back to cited text no. 76
Mitchell RP, Baumgartner JC, Sedgley CM. Apical extrusion of sodium hypochlorite using different root canal irrigation systems. J Endod 2011;37:1677-81.  Back to cited text no. 77
Mitchell RP, Yang SE, Baumgartner JC. Comparison of apical extrusion of NaOCl using the EndoVac or needle irrigation of root canals. J Endod 2010;36:338-41.  Back to cited text no. 78
George R, Walsh LJ. Apical extrusion of root canal irrigants when using Er:YAG and Er, Cr:YSGG lasers with optical fibers: An in vitro dye study. J Endod 2008;34:706-8.  Back to cited text no. 79
Khan S, Niu LN, Eid AA, Looney SW, Didato A, Roberts S, et al. Periapical pressures developed by nonbinding irrigation needles at various irrigation delivery rates. J Endod 2013;39:529-33.  Back to cited text no. 80
Park E, Shen Y, Khakpour M, Haapasalo M. Apical pressure and extent of irrigant flow beyond the needle tip during positive-pressure irrigation in an in vitro root canal model. J Endod 2013;39:511-5.  Back to cited text no. 81
Jezeršek M, Jereb T, Lukač N, Tenyi A, Lukač M, Fidler A. Evaluation of apical extrusion during novel Er:YAG laser-activated irrigation modality. Photobiomodul Photomed Laser Surg 2019;37:544-50.  Back to cited text no. 82
Aguiar B, Gomes F, Ferreira C, de Sousa BC, Costa FW. Hypochlorite-induced severe cellulitis during endodontic treatment: Case report. South Bras Dent J 2014;11:199-203.  Back to cited text no. 83
Bradford CE, Eleazer PD, Downs KE, Scheetz JP. Apical pressures developed by needles for canal irrigation. J Endod 2002;28:333-5.  Back to cited text no. 84
Boutsioukis C, Verhaagen B, Versluis M, Kastrinakis E, Wesselink PR, van der Sluis LW. Evaluation of irrigant flow in the root canal using different needle types by an unsteady computational fluid dynamics model. J Endod 2010;36:875-9.  Back to cited text no. 85
Tenore G, Palaia G, Ciolfi C, Mohsen M, Battisti A, Romeo U. Subcutaneous emphysema during root canal therapy: Endodontic accident by sodium hypoclorite. Ann Stomatol (Roma) 2017;8:117-22.  Back to cited text no. 86
Rutala WA, Weber DJ. Uses of inorganic hypochlorite (bleach) in health-care facilities. Clin Microbiol Rev 1997;10:597-610.  Back to cited text no. 87
Karatas E, Ozsu Kirici D, Arslan H. Postoperative pain after the use of sodium hypochlorite gel and solution forms: A randomized clinical study. Eur Endod J 2021;6:34-7.  Back to cited text no. 88
Nesser SFA, Bshara NG. Evaluation of the apical extrusion of sodium hypochlorite gel in immature permanent teeth: An in vitro study. Dent Med Probl 2019;56:149-53.  Back to cited text no. 89
Reeh ES, Messer HH. Long-term paresthesia following inadvertent forcing of sodium hypochlorite through perforation in maxillary incisor. Endod Dent Traumatol 1989;5:200-3.  Back to cited text no. 90
Paschoalino Mde A, Hanan AA, Marques AA, Garcia Lda F, Garrido AB, Sponchiado EC Jr. Injection of sodium hypochlorite beyond the apical foramen – A case report. Gen Dent 2012;60:16-9.  Back to cited text no. 91
Mehdipour O, Kleier DJ, Averbach RE. Anatomy of sodium hypochlorite accidents. Compend Contin Educ Dent 2007;28:544-50.  Back to cited text no. 92
Farook SA, Shah V, Lenouvel D, Sheikh O, Sadiq Z, Cascarini L, et al. Guidelines for management of sodium hypochlorite extrusion injuries. Br Dent J 2014;217:679-84.  Back to cited text no. 93
Bramante CM, Duque JA, Cavenago BC, Vivan RR, Bramante AS, de Andrade FB, et al. Use of a 660-nm laser to aid in the healing of necrotic alveolar mucosa caused by extruded sodium hypochlorite: A case report. J Endod 2015;41:1899-902.  Back to cited text no. 94

Correspondence Address:
Dr. A R Vivekananda Pai
Department of Conservative Dentistry and Endodontics, Faculty of Dentistry, Manipal University College Malaysia, Jalan Batu Hampar, Bukit Baru, 75150 Melaka
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcd.jcd_422_22

Rights and Permissions


  [Table 1], [Table 2], [Table 3], [Table 4]


    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Email Alert *
    Add to My List *
* Registration required (free)  

    Article Tables

 Article Access Statistics
    PDF Downloaded117    
    Comments [Add]    

Recommend this journal