TAD failure
- TAD failure rate 5%
- Main cause due to root contact 80%
Which teeth to TADs contact and fail? Hee-Moon 2006
- Maxilla: contact is usually with the distal tooth:
- Mandible: RHS contact with distal teeth
- Mandible: LHS contact with mesial teeth
How to avoid root contact?
- Increase oblique path – 30 o
- TAD further apical – greater root divergence
- Greater cortical plate engagement = more stable
Root proximity from radiograph
- TADs appearing to contact the roots were likely to be successful – 83%
- If TADs did not appear to contact root surface, success rate higher 98%
Greater failure in mandible
- Potential microcrack due to insertion torque
- Torque 15Nm = crack in bone, 10Nm no crack
Sinus perforation
- In 10% of cases
Root fracture
- Possible with self drilling TADs
Increase midpalatal TAD success suggestions
- Avoid mid-palatal suture
- Place anterior to 1st molar
- Embedded depth should be 4.5mm +
- 2mm screw with pre drilling
- Larger torque improves stability up to 30Nm
