OWN - Quintessenz Verlags-GmbH
CI - Copyright Quintessenz Verlags-GmbH
OCI - Copyright Quintessenz Verlags-GmbH
TA - Int J Oral Maxillofac Implants
JT - The International Journal of Oral & Maxillofacial Implants
IS - 0882-2786 (Print)
IP - 3
VI - 36
PST - ppublish
DP - 2021
PG - 423-431
LA - en
TI - Cortical Thickness, Bone Density, and the Insertion Torque/Depth Integral: A Study
Using Polyurethane Foam Blocks
FAU - Di Stefano, Danilo Alessio
AU - Di Stefano D
FAU - Piattelli, Adriano
AU - Piattelli A
FAU - Iezzi, Giovanna
AU - Iezzi G
FAU - Orlando, Francesco
AU - Orlando F
FAU - Arosio, Paolo
AU - Arosio P
OT - bone density
OT - cortical thickness
OT - insertion torque
OT - primary stability
OT - torque-depth curve integral
AB - Purpose: Bone density and implant primary stability parameters have been introduced
that are based on calculating (1) the average of the instantaneous torque needed to
keep the rotation speed of a bone density probe constant while it descends into bone
or (2) the integral of the instantaneous torque-depth curve at implant insertion (I),
a quantity that is equal to the insertion energy multiplied by a constant. This study
aimed to determine how these two quantities are affected by the presence and
thickness of a cortical bone layer. Materials and methods: An instantaneous
torque-measuring micromotor was used to measure the density of six double-layer
polyurethane foam blocks mimicking different cortical/cancellous bone combinations.
Twenty measurements per block were collected, averaged, and compared. The insertion
torque and the integral (I) of the instantaneous torque-depth curve at implant
insertion were recorded when 20 3.75 × 12-mm cylindrical implants were inserted in
each of nine blocks, including three single-layer blocks simulating the absence of a
cortical layer, under three final cortical (countersink) preparations: 4.0, 3.7, and
3.5 mm. The relationship between the insertion torque, the integral of the
instantaneous torque-depth curve at implant insertion (I), cortical thickness, and
the final diameter preparation were investigated with regression and best-fit slope
analyses. Results: Bone density measurements showed that the average of the
instantaneous torque at probing allowed differentiation of five of six different bone
classes (hard-hard, hard-normal, hard-soft, normal-normal, normal-soft, soft-soft);
the post hoc analysis of variance (ANOVA) comparisons were all statistically
significant except for the hard-soft-normal-soft pair. The insertion torque and the
integral (I) of the instantaneous torque-depth curve at implant insertion increased
proportionally with cortical bone thickness (Pearson's r > 0.96 in all cases).
Conclusion: When the final preparation varied from 3.7 mm to 3.5 mm, the insertion
torque-thickness plot slope did not change significantly, while that of the
instantaneous torquedepth curve integral (I)-thickness plot did change, suggesting
that the torque-depth curve at implant insertion integral (I) may detect the increase
in implant stability consequent to slight anatomical changes or changes in the site
preparation protocol better than the insertion torque when measuring the cortical
bone layer stress while undergoing insertion. These findings concerning bone density
and primary stability should be investigated further using different experimental
settings. If confirmed, they might generate improvements in the predictability of
implant and prosthetic rehabilitation outcomes.
AID - 1579995