1. Drilling Technique for Optimal Performance Joel Gillard Karsten Zuendel Randy Huebner Portland, Oregon USA SIGN Conference 2009

2. Drilling Performance Factors 1.Cutting edge geometry for material drilling into: bone vs metal 2.Cutting edge retention: hardness vs. toughness WoodBoneMetal Cutting Edge

3. Drilling Performance Factors

4. 3.Drilling technique: feed & speed Tool life & Bone temperature Above 47 o C for over 1 minute bone necrosis Eriksson et al 1984 Scand J Plast Reconstr Surg 18:261–268

5. Drill Testing Outcomes Feed & Speed for 3.5mm SIGN drill – Tool Life & Temp Practical drilling techniques Ideas for improving SIGN drill

6. Methods 2 speeds: 400 & 1100 RPM 2 feeds: 7 lbs (3 kg) & 17 lbs (8 kg) Synthetic bone & pig femur 3.5mm SIGN drill Commercial general purpose 3.5mm drill Record time & temperature Note wear of cutting edge

7. Results

8. New400 - 71100 - 7400 - 171100 - 17Bullet

9. Key article comparison Bullet SIGN

10. Discussion Highest temperature 96 o C recorded for the highest speed lowest force 2900 RPM / 2 Kg

11. Discussion

13. RPM = 800 Bullet drill performs better than ortho equivalent drills, producing significantly less temperatures

14. Higher Temp with Higher RPMs (1100 – 1400) Lower Temp with Higher Feed Rates

15. Conclusion Push on the drill (17 lbs / 8 kg): more is better than less Faster RPM (1100) cuts quicker, but only if you push hard (17 lbs, 8 Kg), otherwise temp drill dulls Pulse or Peck every 2 – 3 sec Clears debris Reminder to push

16. Conclusion Some irrigation is better than none Drill a small (2mm) hole first followed by 3.5mm All drills will eventually become dull, but the can be resharpened, find a craftsman Drills need to be properly used, cared for and maintain to have a long life