Bone Damage Related to Miniscrew Implants in Maxilla and Mandible

Objectives:  The use of miniscrew implants (MSI) as part of orthodontic treatment is a common practice.  Bone damage drives remodeling which is crucial for implant adaptation and long-term success. The goal of this study was to quantify the amount of bone damage caused by two types of MSIs, self-drilling (SD) and non-self drilling (ND), just after implantation.

Methods:  Once IACUC approval was attained, two types of MSIs (Tomas, Dentaurum, USA), SD (n=10) and ND (n=12), were inserted into the maxilla and mandible of four adult, male, Beagle dogs after sacrifice.  The MSIs were placed in the posterior mandible, anterior mandible, and posterior maxilla.  Bone blocks containing the MSI were cut, bulk stained with basic fuchsin, and embedded in methyl methacrylate, sectioned, and mounted onto slides.  Standard histomorphometric methods were used to calculate percent microdamage (%MDx) and percent diffuse damage (%DDx).  The damage was measured at the following distances from the implant-bone interface: 0-0.5 mm, 0.5-1.0 mm, and 1.0-1.5 mm. Data were analyzed using a repeated measures ANOVA and Tukey-Kramer procedure.

Results:  Mean %MDx values ranged from 0-4% and those for %DDx from 10.4-59.0%.  When analyzing %DDx, ANOVA revealed a significant (p=0.0001) effect based on distance from implant but no significant (p=0.83) effect for type of implant, or the interaction between type and distance (p=0.58). When analyzing %MDx, ANOVA showed no significant effect (p=0.13) based on the implant type, distance from implant (p=0.14), or their interaction (p=0.11).

Conclusion:  Insertion of both types of implants produces severe localized damage of bone.  When measuring all bone damage after implantation, similar levels of damage were caused by both SD and ND MSIs.  However, the damage diminished as a function of distance from the implant interface, with bone closest to the implant being most damaged.