A Comparison of Under Drilling and Under Drilling with Osseodensification for the Improvement of the Implant Primary Stability
Joshua D Gold, DMD, Raphael Delgado-Ruiz, PhD, Tanya Somohano, DMD
Dept. of Prosthodontics and Digital Technology
Stony Brook University, School of Dental Medicine, Stony Brook, NY
Primary stability can be defined as a mechanical stability at the time of surgery1. There are multiple factors that contribute to the implant stability such as the bone quality and quantity, type of implant and technique used for placement2. Under drilling (implant bed preparation with a drill diameter narrower than the implant diameter)3 and Osseodensification (use of a special drill that increase bone density and expand the the osteotomy)4 techniques are frequently used for enhancing the primary stability in poor density bone.
But until now there is a lack of knowledge about the use of the under drilling method combined with the osseodensification technique in different experimental bone qualities.
To determine the primary stability of the combined technique (under drilling and osseodensification) for implants placed in porcine ribs.
The hypothesis of this study is that the combined technique would enhance the primary implant stability when compared with the under drilling technique alone.
The sample size was calculated as 20 per each experimental group using the online resource http://www.raosoft.com/samplesize.html, for a power of 95% and a 5% alpha error.
This was an experimental in-vitro study performed in porcine ribs (fresh from the butcher). All soft tissues were removed with a scalpel to expose bone before implant bed preparation (Figure 1a) Two different techniques were used for the preparation of the implant bed. Under preparation with Zimmer drills (Zimmer Biomet FL, USA), and under preparation + osseodensification with Versah drills (Versah LLC MI, USA).
Drilling protocol for Zimmer was followed (pilot drill, 2.3mmD, 2.8mmD, 3.4mmD all with clockwise rotation). Drilling protocol for Versah was followed (pilot drill, 2.3mmD, 3.0mmD, 3.5mmD all with counter clockwise rotation with the exception of the pilot drill). After the implant beds were prepared, Zimmer corevent implants (Zimmer Biomet FL, USA) with 4.1mm diameter were inserted until the implant platform was flush with the bone surface and the primary stability was measured with the perio test (Medizintechnik Gulden Modatautal, Germany) and the osstell (Osstell USA MD, USA) devices.
The perio test value (PTV) was obtained by positioning the tip of the instrument perpendicular to the implant transfer. The average of three consecutive measurements was obtained per each implant. The RFA (resonance frequency analysis) value was obtained with the Osstell device by inserting a smart pick into each implant and using the Osstell wand to record the RFA values (Figure 2). Once PTV and RFA values were documented statistical analysis was performed.
Implant stability evaluated by PTV (Figure 3 and Table 1) and ISQ values (Figure 4 and Table 2) showed higher mean stability for the under drilling by Zimmer drills compared to the under drilling with Versah drills.
With in the limitations of this in-vitro study, it can be concluded that under-drilling with Zimmer drills provided better primary stability then under drilling with Versah drills.