This is the case of dental negligence which falls within the ambit of medical negligence. Leaving of instruments during the canal procedures is termed as an endodontic procedure which attracts second highest number of malpractice claims in medical negligence. Negligence constitutes:
Duty of care
Breach of such duty, and
The Consumer Protection Act, 1986: You are entitled to compensation under the Consumer Protection Act, 1986.
However, this protection is subject to a personal contract of service between you and the medical practitioner. If there were any terms/agreements/waivers that you were informed of or were made to sign any document regarding the same, you will not be entitled to any compensation.
In a case otherwise, you fall within the ambit of the definition of a consumer under the said Act
and can claim compensation.The Supreme Court
has observed that under the civil law, victims of negligence can get relief in the form of compensation from a civil court or the consumer forum
Proof of damage:
In order to claim any kind of compensation, the onus is on you to prove that the practitioner has failed to adhere to the reasonable standards of dental practice resulting into the damage caused to you.
Filing of complaint: You can file a complaint against the concerned dentist in the District Forum under Section 12 of the CPA with a nominal fee of Rs. 200.
You do not need any legal representative for this; you may represent your own case. The limitation period for filing the case with the District Forum is 2 years.
The decision of the District Forum is appealable and the appeal can go all the way to the Supreme Court with a limitation period of 30 days for each of the preceding forums.
The quantum of compensation is subject to the assessment of damage by the Consumer Forum.
Section 2 (1) (o) of the Consumer Protection Act (CPA), 1986; see Indian Medical Association v. V.P. Shantha and ors. [AIR (1996) SC 550) 
Section 2(1) (d) of the CPA, 1986  Jacob Mathew v. State of Punjab
2005 SSCl.COM 456 Criminal Appeal No. 144-145 (2005)  Kanhaiya Kumar Singh v. Park Medicare Research Centre (2000) NCJ (NC) 12 
Section 24 (A), CPA. 
Sections 15, 19 and 23, CPA. 
Rebecca Samervel, Consumer Forum Tells Dentist to Pay Rs. 2 Lakhs for faulty Treatment
[TOI, Oct. 12, 2015]