title: Influence of CAD/CAM tool and material on tool wear and roughness of dental prostheses after milling.
abstract: BACKGROUND
  Computer-aided design/computer-aided manufacturing (CAD/CAM) machining influences the surface roughness of dental restorations and tool wear. Roughness must be suitable to meet clinical requirements, and the tool must last as long as possible.
  
  
  OBJECTIVE
  The purpose of this pilot study was to investigate the influence of the CAD/CAM tool-material couple on tool wear and surface roughness after milling.
  
  
  METHODS
  Three tools (Lyra conical tool Ø1 mm; GACD SASU, Lyra conical tool Ø1.05 mm; GACD SASU, and Cerec cylinder pointed tool 12S; Sirona Dental Systems GmbH) and 3 CAD/CAM materials (Lava Ultimate; 3M ESPE, Mark II; VITA Zahnfabrik H. Rauter GmbH, and Enamic; VITA Zahnfabrik H. Rauter GmbH) were tested. The tool wear of 6 tool-material couples at a feed rate of 2 m/min was analyzed before and after 8 minutes of flank and climb milling with optical and scanning electron microscopy (SEM) observations and tool weighing. The surface roughness after milling was observed for 9 tool-material couples for flank and climb milling. Feed rates of 1, 2, 3, and 4.8 m/min were used for each couple. Ra, Rt, Rz, Sa, Sq, and Sz roughness criteria were measured. A paired comparison of tool-material couples was conducted with the Kruskal-Wallis test.
  
  
  RESULTS
  The Mark II material led to more severe tool wear. Milling of Lava Ultimate resulted in chip deposits on the tool grit. The Cerec cylinder pointed tool 12S was less worn for each material tested. The Cerec cylinder pointed tool 12S and the Lyra conical tool Ø1.05 mm provided similar roughness measurements for the 3 materials tested. The Lyra conical tool Ø1.05 mm tool provided better roughness than the Lyra conical tool Ø1 mm tool for the Enamic material.
  
  
  CONCLUSIONS
  Tool lifetime calculated by volume of milled material removed should be the measure provided by CAD/CAM manufacturers instead of a number of blocks. This tool lifetime should be provided for the milling conditions associated with the material milled. Material hardness and tool grit are key factors for achieving a given roughness.
authors.affiliation: Senior Lecturer, Department of Biomaterials, Faculty of Dental Surgery, Paris-Descartes University, Paris, France. Electronic address: lebon@iutsd.univ-paris13.fr.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Lebon
authors.affiliation: Senior Lecturer, Department of Biomaterials, Faculty of Dental Surgery, Paris-Descartes University, Paris, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Tapie
authors.affiliation: Professor, Laboratory of Soil Mechanics, Structures and Materials, Chatenay Malabry, France.
authors.forename: Elsa
authors.initials: E
authors.lastname: Vennat
authors.affiliation: Professor and Senior Lecturer, Department of Biomaterials, Faculty of Dental Surgery, Paris-Descartes University, Paris, France.
authors.forename: Bernardin
authors.initials: B
authors.lastname: Mawussi
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D017076:Computer-Aided Design / Q000295:instrumentation*; D003764:Dental Materials / Q000737:chemistry*; D003776:Dental Porcelain / Q000737:chemistry; D017266:Dental Prosthesis; D017267:Dental Prosthesis Design / Q000295:instrumentation*; D018130:Diamond / Q000737:chemistry; D006244:Hardness; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008422:Materials Testing; D008853:Microscopy; D008855:Microscopy, Electron, Scanning; D053761:Nanocomposites / Q000737:chemistry; D010865:Pilot Projects; D017680:Potassium Compounds / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors
chemical_list: D000538:Aluminum Silicates; D003188:Composite Resins; D003764:Dental Materials; D017680:Potassium Compounds; C082340:Vita Mark II; D003776:Dental Porcelain; C016447:feldspar; D018130:Diamond