This is a dental malpractice action against Mrs. Elkins' longtime dentist, based upon allegations that plaintiff suffered severe periodontal disease resulting in the loss of four teeth and other injuries due to defendant's failure to properly diagnose or treat her condition or timely refer her to a periodontist. When this matter was previously before us ( 253 A.D.2d 601), we reversed the jury's verdict in favor of plaintiffs and dismissed the complaint on the ground that there was simply no valid line of reasoning and permissible inferences that could possibly have led to the conclusion that plaintiffs demonstrated any malpractice on defendant's part. The Court of Appeals disagreed and has reversed our order and remitted the matter to us for consideration of all other issues within our plenary intermediate appellate authority. In so ruling, the Court found that "[t]he evidence, when viewed in the light most favorable to the plaintiff, is legally sufficient to support the jury's verdict". ( 93 N.Y.2d 938, 939.)

Since we previously stated that, were we not dismissing the complaint, we would have ordered a new trial because of the trial court's failure to instruct the jury, as requested, as to the issue of comparative negligence, we now do so.

It was the crux of the defense that plaintiff bore a major responsibility for the development of her periodontal disease due to her heavy use of prescription drugs and tobacco, her failure to furnish a complete and accurate medical history and her undue delay of treatment after defendant's discovery of tb periodontal condition. The principle of comparative negligenc is applicable to medical or dental malpractice ( see, Suria Shiffman, 67 N.Y.2d 87; Bellas v. Kurpis, 182 A.D.2d 542) and under the facts of thiscase, it was reversible error not to chary comparative negligence.