Table 3 Comparisons of concavity depth (CD, mm), concavity angle (CA, degree), torque (degree), and deep bone thickness (dBT, mm) at different levels (0, 5, and 10 mm) in the “perforation” and “non-perforation” sites of investigated teeth in anterior mandibular region

 Concavity depth (CD)

4.44 (1.96)

4.2 (3.0)

5.59 (1.93)

5.6 (2.9)

4.12 (1.85)

3.8 (2.6)

< 0.001

 Cavity angle (CA)

144.95 (7.36)

145.4 (9.4)

140.53 (7.13)

142.1 (9.0)

146.17 (6.95)

146.7 (8.8)

< 0.001

 dBT (0)

8.20 (2.02)

8.0 (2.7)

6.87 (1.67)

6.6 (2.6)

8.57 (1.95)

8.4 (2.8)

< 0.001

 dBT (5)

9.41 (2.04)

9.3 (2.6)

8.01 (1.79)

8.0 (2.8)

9.80 (1.93)

9.7 (2.6)

< 0.001

 dBT (10)

10.84 (2.00)

10.8 (2.5)

9.77 (1.96)

10.0 (2.0)

11.14 (1.90)

11.0 (2.6)

< 0.001

 Torque (T)

161.40 (8.62)

161.9 (12.1)

166.29 (7.94)

167.4 (11.3)

160.05 (8.32)

160.8 (10.9)

< 0.001