Influence of CAD/CAM tool and material on tool wear and roughness of dental prostheses after milling.

STATEMENT OF PROBLEM 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. PURPOSE 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. MATERIAL AND 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. CONCLUSION 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.

[1]  Richard van Noort,et al.  The future of dental devices is digital. , 2012 .

[2]  Ling Yin,et al.  Surface integrity and removal mechanism in simulated dental finishing of a feldspathic porcelain. , 2006, Journal of biomedical materials research. Part B, Applied biomaterials.

[3]  Stephen Bayne,et al.  FDI World Dental Federation: clinical criteria for the evaluation of direct and indirect restorations—update and clinical examples , 2010, Clinical Oral Investigations.

[4]  J A Sorensen,et al.  A rationale for comparison of plaque-retaining properties of crown systems. , 1989, The Journal of prosthetic dentistry.

[5]  M. Tuntiprawon,et al.  Effect of tooth surface roughness on marginal seating and retention of complete metal crowns. , 1999, The Journal of prosthetic dentistry.

[6]  Han Huang,et al.  Ceramic Response to High Speed Grinding , 2004 .

[7]  Z. Pálmai,et al.  Proposal for a new theoretical model of the cutting tool's flank wear , 2013 .

[8]  S D Heintze,et al.  Surface roughness and gloss of dental materials as a function of force and polishing time in vitro. , 2006, Dental materials : official publication of the Academy of Dental Materials.

[9]  J. Gardeniers,et al.  The effect of surface roughness on direct wafer bonding , 1999 .

[10]  Ling Yin,et al.  Micro-fine finishing of a feldspar porcelain for dental prostheses. , 2008, Medical engineering & physics.

[11]  M S Scurria,et al.  Surface roughness of two polished ceramic materials. , 1994, The Journal of prosthetic dentistry.

[12]  Ling Yin,et al.  Abrasive machining of porcelain and zirconia with a dental handpiece , 2003 .

[13]  Heike Rudolph,et al.  CAD/CAM-machining effects on Y-TZP zirconia. , 2004, Dental materials : official publication of the Academy of Dental Materials.

[14]  Albert Mehl,et al.  Wear characteristics of current aesthetic dental restorative CAD/CAM materials: two-body wear, gloss retention, roughness and Martens hardness. , 2013, Journal of the mechanical behavior of biomedical materials.

[15]  M. Nouari,et al.  Experimental analysis and optimisation of tool wear in dry machining of aluminium alloys , 2003 .

[16]  S. Liang,et al.  Predictive modeling of surface roughness in grinding , 2003 .

[17]  A. Mehl,et al.  New CAD/CAM materials and blocks for chairside procedures. , 2013, International journal of computerized dentistry.

[18]  P. Ashworth,et al.  Psychological effects of aesthetic dental treatment. , 1998, Journal of dentistry.

[19]  Ji-hua Chen,et al.  Effect of different grit sizes of diamond rotary instruments for tooth preparation on the retention and adaptation of complete coverage restorations. , 2012, The Journal of prosthetic dentistry.

[20]  Albert J Feilzer,et al.  The fracture resistance of a CAD/CAM Resin Nano Ceramic (RNC) and a CAD ceramic at different thicknesses. , 2014, Dental materials : official publication of the Academy of Dental Materials.

[21]  C. Fagnano,et al.  Raman spectroscopy in the study of biocompatibility. , 1992, Clinical materials.

[22]  Saskia Preissner,et al.  Clinical Performance of a New Biomimetic Double Network Material , 2013, The open dentistry journal.

[23]  S D Heintze,et al.  Crown pull-off test (crown retention test) to evaluate the bonding effectiveness of luting agents. , 2010, Dental materials : official publication of the Academy of Dental Materials.

[24]  Jean-Pierre Kruth,et al.  Machining of steel with sialon ceramics : influence of ceramic and workpiece composition on tool wear , 1995 .

[25]  F. W. Taylor.  The Art of Cutting Metals , 1907 .

[26]  P Lambrechts,et al.  Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: a review of the literature. , 1997, Dental materials : official publication of the Academy of Dental Materials.