A RARE INCIDENT OF INTRAORAL FORMALIN INJECTION

Formalin is a hazardous chemical that needs careful handling and special storage. It is generally used in den�stry because of its disinfectant and ﬁxa�ve proper�es. Negligence on part of the dental professionals by accidentally injec�ng formalin rather than the original anesthe�c can lead to internal �ssue damage and also may induce a life threatening situa�on. The general prac�ce of storing formalin in the original anesthe�c bo�les and being supported by untrained assistants is the most common reason for this mishap to happen. The opera�ng den�st should be careful and apprehensive of the medicines and chemicals available in the operatory and re-check the solu�on being injected in the case as to not land up in complica�ons because of the negligence. Successful management can be done by cau�ous debridement and empirical medicine therapy.


INTRODUCTION
Formaldehyde, a simple aldehyde with molecular formula CH O at room temperature, is a colorless gas having 2 inflammable proper es with irrita ng pungent odor. It is a highly water-soluble reac ve chemical that has a short biologic half-life. The aqueous 35-40% solu on of formaldehyde mixed with water is known as formalin. Formalin contains a stabilizer usually 10-15% methanol and 48-50% water. Both formaldehyde and formalin have the 1 same chemical formula. Formalin is commonly used as a disinfectant and as a ssue fixa ve for preserving biological 2 specimens for histopathological examina ons. Local anesthe c injec on is delivered with standard protocols to 3 perform various dental procedures. This case report describes a case of accidental injec on of formalin instead of local anesthe c into the buccal mucosa in a 65-year-old man during long buccal nerve block for intralesional steroid injec ons.

CASE REPORT
A case of accidental formalin injec on instead of local anesthesia prior to performing an intralesional steroid injec on in pa ent with oral submucous fibrosis. A 65-yearold male clinically diagnosed with oral submucous fibrosis reported to the department of Oral Medicine and Radiology, College of Dental Surgery, B.P. Koirala Ins tute of Health Sciences (BPKIHS), Dharan, Nepal, for intralesional injec on with steroids. The informed consent regarding the procedure was obtained from the pa ent. Intralesional injec on was to be performed in the bilateral buccal mucosa under local anesthesia. Long buccal nerve block was given. Within a couple of minutes the pa ent started complaining of sharp burning pain sensa on and severe discomfort on the injec on site. The procedure was aborted and was reported to the faculty members. Pa ent was monitored. Blood pressure was 120/80mmHg, pulse was 75 beats/ minute, respiratory rate was 16 breath/minute and temperature was afebrile to touch. Pa ent was reassured. The vial of the local anesthe c agent was checked for the expiry date. Ini ally it was assumed that it was a case of hypersensi vity reac on to local anesthesia. An histaminic drug was given for one week and pa ent was recalled a er 1 week. A er some me while loading the local anesthesia from same vial for another procedure it was found that the seal of local anesthe c bo le was broken (Fig: 1). A er opening the rubber cup, it was found that the vial thought to contain a local anesthe c agent was actually pungent smelling clear liquid which was formalin. A er knowing that it was an accidental injec on of formalin, the pa ent was immediately traced and contacted.  On the next day the pa ent presented with bilateral swelling of the face near the angle of mandible. Swelling was diffuse with size of 4 cm*4 cm with normal overlying skin which was tender on palpa on with no any discharge. As the mouth opening of the pa ent was 20 mm due to preexis ng oral submucous fibrosis, intraoral examina on could not be done properly.   Systemic cor costeroid and an bio c therapy was given along with analgesics. Pa ent was given instruc ons to report the next day for periodic monitoring. On next followup, swelling of the face was decreased and on careful intraoral examina on there was a single well defined ulcer of size 5mm*3mm with slough and necrosis of surrounding ssues was found at the injec on site without pain, pus or blood discharge ( Fig:2, 3). Cure age was done thoroughly and irriga on was done with chlorhexidine mouthwash (0.2%). Pa ent was recalled daily for 1 week for irriga on and evalua on of the ulcer. At the end of one week swelling subsided and the size of the ulcer was decreased. Ulcer was completely healed in two weeks. Subsequent monitoring of the pa ent was conducted via phone for one month, during which there were no reported complaints.

DISCUSSION
Pa ents accidentally exposed to formalin into the intravascular compartment have developed acute hemolysis. In vitro studies revealed that formalin has direct oxida ve ac on on red blood cells. Though, cases of inten onal consump on have presented with fully different set of clinical features like orofacial, pharyngeal and gastrointes nal symptoms like corrosive gastri s with hematemesis, dysphagia and inhala onal pneumoni s with cough, dyspnea, cyanosis and cardiac arrhythmias. Humans exposed to excess of formaldehyde, show several symptoms including respiratory irrita on; watery, itchy eyes; itchy, 3 watery, or stuffy nose; dry or sore throat; and headache. In There should be one predefined area where only local anesthe c bo les are kept. 3. All chemicals that aren't used for injec on must be physically removed from clinical areas. 4. Prac ce of reusing empty local anesthe c bo les for storage of dental chemicals should be discouraged to discourage similar incidents.
5. Local anesthe c bo les, if at all to be reused, should not be used with labels. It should be removed instantly and must retain a new well-stressed label of chemical stored. 6. All the staff working in dental clinics should have a thorough introduc on and knowledge of dental drugs and chemicals used in the clinics and their severe side effects. 7. Clinicians should check and confirm the contents of the syringe before injec ng if it's loaded by the assistant or the den st himself should load the syringe. In future to circumvent similar circumstances, the specific protocols need to be cul vated by the dental prac oners, 5 which have been improved from the regre ul episode.
i) Original anesthe c bo les, if at all to be reused for conserving specimens, must retain a label. ii) Unskilled assistants shouldn't be entertained to work in a dental operatory. iii) It's extremely safe to keep the dental chemicals away from the clinical area, if they aren't indicated for injec on purpose.

CONCLUSION
In our case though accidental administra on of formalin occurred, the pa ent survived without any systemic complica ons. This could be because, the amount of formalin injected was very low. In developing countries, single use cartridges is not used generally due to financial reason. We generally use the original anesthe c solu on vial to store other solu ons. When the refilled solu on is clear, it creates confusion. In case we are reusing the vial, it should be well tagged about the content. Solu on not used for injec on should be kept away from clinical area and employing untrained staff as an assistant should not be done because a small mistake from their side can create a 6 great trouble to both clinician and pa ent. So to prevent similar incidence in future, dental assistants should be trained in handling dental drugs and chemicals. Dental students should be educated on drug safety and toxicity of chemicals used in dental opera ons. Con nuing dental educa on programs should be conducted for awareness among den sts regarding similar mishaps and 7 ways of avoiding the same incident.

PATIENT CONSENT
The wri en consent was obtained from the pa ent.

CONFLICT OF INTEREST
None