Comparison of Primary Stability of Tapered and Parallel Walled Implants in Poor Quality Bone: An in vitro study

ABSTRACT Objectives: Obtaining primary stability upon placement is crucial for predictable healing and long-term success of dental implants. Primary stability is very difficult and challenging to achieve in poorer quality bone. Currently, two of the more common dental implant designs are tapered and parallel walled dental implants. The objective of this study was to determine if there was a difference in the primary stability of tapered and parallel dental implants in poor quality bone. The null hypothesis of this study was that there is no difference in the primary stability of tapered and parallel walled dental implants in poor quality bone. Material and Methods: Two implant designs (tapered and parallel walled dental implants) were evaluated for the primary stability in a medium that represented poor bone quality (Balsa wood). Twenty-four 4.3 x 11.5 mm HahnTM tapered implants (Glidewell Dental Laboratories, Newport Beach, CA) along with a twenty-four 4.3 mm x 11.5 mm parallel walled prototype HahnTM implants (Glidewell Dental Laboratories, Newport Beach, CA) were used. All implants had identical surface texture, diameter, length, thread design, and pitch thereby eliminating extraneous variables. The only difference between the two dental implants was the taper. After implant placement in the poor quality bone medium, resonance frequency analysis was recorded for each implant using the Penguin RFA (Aseptico®, Woodinville, WA). The ISQ scores were uploaded into Stata 16 (StataCorp, College Station, TX) and evaluated. A two-sample t-test was calculated to determine if there was a statistically significant difference in the primary stability between the two implant designs. Results: In the evaluation of 24 tapered and 24 parallel walled implants, the average ISQ value for the tapered was 67.125 +/- 1.974 and the parallel walled was 64.813 +/- 0.93. The 2-sample ttest yielded a p-value = 0.0000. Since the p-value <0.05, there was a statistically significant difference between the ISQ scores of the two implant designs. The null hypothesis was rejected. Conclusion: The results of this in vitro study concluded that the tapered implant design provides greater primary stability than parallel walled implants in poor quality bone