Original article / research
Evaluation of the Coefficient of Friction between Natural Teeth and Restorative Crown Materials: An In-vitro Study
ZC07-ZC11
Correspondence
Dr. Lokesh Sunkala,
Reader, Department of Maxillofacial Prosthodontics and Implantology Army
College of Dental Sciences, Hyderabad-500087, Telangana, India.
E-mail: drlokeshs@gmail.com
Introduction: The use of aesthetic restorative materials, particularly zirconia, has increased in modern dentistry due to their strength and aesthetics. Their frictional behaviour against opposing surfaces is a key factor influencing clinical performance and wear. However, comparative data on friction among enamel, metal-ceramic, and zirconia under standardised conditions is limited.
Aim: To evaluate and compare the Coefficient of Friction (COF) of natural teeth, metal-ceramic crowns, and zirconia crowns against different opposing materials under standardised in-vitro conditions.
Materials and Methods: The present in-vitro study was conducted in the Department of Prosthodontics, CKS Theja Institute of Dental Sciences, Tirupati, Andhra Pradesh, India, from July 2018 to December 2018. Ninety extracted human premolars meeting the inclusion criteria (caries-free, intact structure) were selected and randomly allocated into three groups (n=30): Group A (Natural teeth) Group B (Metal- ceramic) Group C (Zirconia). Each group was further subdivided based on opposing materials (metal, metal-ceramic, zirconia; n=10). Specimens were mounted in acrylic blocks and subjected to friction testing using a pin-on-disc tribometer under a constant load of 20 N for one hour at 37°C with continuous lubrication. The COF was calculated. Statistical analysis was performed using One-way Analysis of Variance (ANOVA) with significance set at p<0.05
Results: Natural teeth showed the lowest COF against metal discs (0.073±0.011) and highest against metal-ceramic discs (0.402±0.028). Zirconia discs showed intermediate values (0.343±0.021). Metal-ceramic crowns demonstrated lowest COF against metal (0.124±0.018) and highest against zirconia (0.338±0.027). Zirconia crowns showed lowest COF against metal (0.266±0.020) and highest against metal-ceramic (0.470±0.035).
Conclusion: Frictional behaviour varied significantly among materials. Metal surfaces demonstrated the most favourable performance, while zirconia provided a balance between aesthetics and acceptable properties.