The use of toxic materials should be avoided, and even common sealers that do not release formaldehyde can result in paraesthesia when in contact with surrounding neural tissues. Gross overextension of root canal filling material and/or sealer is potentially harmful, particularly when in contact with vital structures such as the inferior alveolar nerve or maxillary sinuses. Gutta-percha points cannot be sterilised by traditional means, but rapid disinfection before use by placing the cones with 70 % isopropyl alcohol, 2 % chlorhexidine or 1–5 % NaOCl is effective. Therefore, the nominal diameter and taper values as listed by the manufacturer may vary greatly and still be in accordance with the ‘standards’. For example, a size #30 cone has an allowable tip diameter of 0.23–0.37 mm. Such tolerance means that cones of one size can theoretically span more than one size above and/or below the stated size. However, even if the manufacturers are following the current standards, the accepted diameter tolerance levels vary from 0.05 to 0.07 mm, depending on the cone size. As clinicians we expect that the diameter and tapers of GP cones to be accurate with no variability. Feather-tipped points permit individual and specific cone fitting to the prepared root canal. Greater taper points are available in 4 % and 6 % taper to match modern rotary preparation techniques. Accessory points have fine tips and variable taper to facilitate and improve lateral compaction. Gutta-percha points are manufactured in various forms including standardised points that match the ISO sizes and have a 2 % taper. Gutta-percha cones consist of approximately 20 % gutta-percha, 65 % zinc oxide, 10 % radiopacifiers and 5 % plasticisers.
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