TG-O Modified TG Periodontal Chisel TG-O Modified TG Periodontal Chisel CTG-O The CTG-O Chisel is used for removing and recontouring bone with 3.2mm working ends. Where to Buy x Category Dealer PartnersSales RepresentativeStrategic MarketsSchools RepresentativeAccutron™ Equipment Sales Zip Code Find RepresentativeReset Select a category, input a zip code and click on Find Representative, or explore the complete list here.