Maxillary bone necrosis following the use of formaldehyde containing paste – case report

Igor Radović1, Lado Davidović1, Smiljka Cicmil2, Slavoljub Tomić2, Dragan Ivanović3, Ljiljana Bjelović1 University of East Sarajevo, Faculty of Medicine, Department of Dental Pathology, Foča, Republika Srpska, Bosnia and Herzegovina; University of East Sarajevo, Faculty of Medicine, Department of Oral Rehabilitation, Foča, Republika Srpska, Bosnia and Herzegovina; University of East Sarajevo, Faculty of Medicine, Department of Pediatric and Preventive Dentistry and Orthodontics, Foča, Republika Srpska, Bosnia and Herzegovina


INTRODUCTION
Successful local anesthesia and performing pain-free root canal treatment may be a challenge for dentists. Cohen et al. reported that 39% of patients who had irreversible pulpitis of the mandibular molar remained sensitive to a cold test after administration of an inferior alveolar nerve block with 2% lidocaine [1]. In cases of acute symptomatic pulpitis, particularly in the mandibular molar, where profound anesthesia was previously difficult to achieve because of technical or anatomical problems, dental clinicians used arsenic or paraformaldehyde paste to devitalize inflamed painful pulp. Pulp necrotizing agents are toxic and exhibit non-selective action. Effect of paraformaldehyde paste is not confined to the pulp but it also affects surrounding tissues if it comes into contact, directly or by diffusion through dentin. If not placed correctly, it may lead to local complications such as damage to interdental papilla, destruction of periodontal ligament, or the formation of periapical, interradical and lateral damage of periodontal bone tissue [2,3].
The purpose of this article is to present the complications caused by inadequate application of paraformaldehyde-based pulp devitalizer on periodontal and bone tissues and its treatment.

CASE REPORT
A 23 year old male patient visited our clinic asking for advice and complained about pain in upper first right molar region. He reported that root canal treatment has been started by his dentist 3 month earlier. Due to extreme pain during access preparation caused by ineffective anesthesia, the patient was told that the pulp devitalizing paste was applied. It was later confirmed (by phone) that it was a paraformaldehyde paste (Depulpin, Voco, GmbH, Cuxhaven, Germany). Shortly after the placement of the paraformaldehyde paste, the patient experienced pain and this feeling persisted even after endodontic treatment was completed. The patient called his dentist and he was told to take some antibiotics and analgesics. However, the patient's complaints did not resolve and he came to our clinic for further evaluation and management.
Clinical examination revealed a crater-like lesion located on the interdental gingiva between upper right second premolar and first molar (tooth #15 and 16), as well as periodontal pocket in the same region ( Figure 1). Second class composite fillings (mesio-occlusal) were observed on both teeth. A radiograph revealed incomplete root canal treatment of tooth 16 (only the palatal canal was obturated) and severe intraosseous defect between teeth 15 and 16 ( Figure 2). Sensitivity of the tooth 15 to the electric pulp test was absent.
Disinfection of the mouth was performed with chlorhexidine 0,2%, and under local anaesthesia, the full thickness periodontal flap was raised both buccally and palatally, necrotic bone was removed and curettage of the cavity was carried out (Figure 3, 4, 5). The surgical site was irrigated with sterile physiological saline. After curettage and irrigation of the area, the defect was filled with xenograft of bovine origin ( Figure 6). The flap was sutured in place and periodontal dressing was given (Figure 7). The patient was prescribed antibiotics for seven days (amoxicillin 500 mg 3×1 and metronidazole 400 mg 3×1).
After three months, endodontic treatment was performed on tooth 15, as well as retreatment on tooth 16 ( Figure 8). After surgical procedure and endodontic treatment completion all symptoms disappeared.

DISCUSSION
Dentists often face difficulties during endodontic treatment, when there is failure of anesthesia in teeth diagnosed with irreversible pulpitis. Various agents are used to devitalize extremely painful pulps prior to extirpation. Paraformaldehyde-containing products are commonly used for this purpose. Paraformaldehyde leads to coagulation and denaturation of cell wall proteins, which results in the arrest of all vital cell functions. The tissue becomes "fixed, " and this state of fixation is irreversible [3,4]. Despite of its clinical benefit, the use of paraformaldehyde containing paste in such circumstances may lead to many noxious effects on the host tissue. In addition to damage of interdental papilla, these agents can diffuse deeper into the bone and with their effect, lead to circulatory disorders and consequent necrosis. These changes may create a precondition for bone infection or localized osteomyelitis [5][6][7][8]. Caution should be exercised during     its use, by properly isolating surrounding tissues from the tooth. Proper application implies complete removal of all carious masses and application of the agent directly to the previously made dental pulp microperforation at a distance of at least 2 mm from the edge of the cavity, for a period not longer than two weeks. In order to prevent microleakage and eliminate the possibility of diffusion of the devitalizing agent towards the gingiva, the application of temporary filling needs to be carried out in layers.
In the case described here, depulpin was probably in direct contact with alveolar bone or soft tissue because of an inadequate temporary restoration. This resulted in severe complications, such as pain, loss of sensitivity of tooth 15, gingival necrosis and bone necrosis. This case required surgical treatment to remove necrotic alveolar bone and sequestrum in order to maintain circulation of the supporting tooth structure.
A study by Ozgöz et al. reported cases of complications occured after the application of paraformaldehyde-based paste during endodontic treatment. Clinical and radiological findings indicated pain, gingival necrosis, and enlargement of the periodontal ligament and loss of lamina dura. Inadequate molar anesthesia was reported as the most common cause of devitalization agents aplication [9]. Similar changes after devitalization of the upper molar were reported in case report by Srivastava et al.
where, in addition to the changes described, the resulting periodontal pocket, 11 mm in depth, was diagnosed [3]. A study by Stabholz and Blush and another study by Di Felice and Lombardi reported necrotic bone and gingiva that resulted from paraformaldehyde containing paste used during root canal treatment [10,11]. Similar cases of paraformaldehyde -related tissue necrosis are occasionally reported, with severe consequences [12,13].
A study by Hülsmann et al. reported that marginal leakage of temporary filling material may result in diffusion of paraformaldehyde containing paste into the periodontal tissues [14]. Tortorici et al. reported three cases of maxillary bone necrosis following the use of formaldehyde containing paste. Each of these three cases resulted in significant damage to periodontal and bone tissues and tooth loss in the affected region [4]. Lee et al. described two cases of osteomyelitis after the use of paraformaldehyde containing paste. In the first case, the clinician applied Depulpin on the perforation site inside the pulp chamber, and in the second case Depulpin was in direct contact with soft tissue [8].
Although effective, the use of paraformaldehyde is not without risk as there may be unfavorable adverse effects on soft tissues and bone. Unfortunately, sometimes unintentional leakage may occur. This may not only lead to superficial mucosal injuries but may also penetrate deeper into the bone and cause its necrosis. Such toxic chemical agents should be used very cautiously in the oral cavity,