Implant Stability After Motor-Driven Graftless Sinus Elevation: a Cohort Study

Objectives: The aim of this study is to evaluate stability of implants installed using motor-driven drills simultaneously with graftless crestal sinus elevation.
Methods: This is a prospective cohort study with the following inclusion criteria: Patients requesting implant treatment in the posterior maxilla with residual ridge height of 6mm or more, elevated height does not exceed 3mm, controlled diabetic patients and mild smokers were included. All implants were installed using motor-driven drills simultaneously with a graftless crestal sinus elevation. All implants used were Straumann BLT implants. Implant stability was measured at baseline using resonance frequency analysis (RFA) and before final restoration. The average implant stability quotient (ISQ) was calculated and compared to a known clinically acceptable value of 65 using a single sample t-test.
Results: Twenty-nine patients (17 males and 12 females) with 34 implants were included in this study. Mean age was 53 (29-65). Mean duration between the baseline RFA reading and pre-restoration was 16 weeks (6-32). Mean implant length was 9.4 (8-12) and mean implant width was 4.4 (3.3-4.8). Mean baseline RFA was 72.7 ISQ (48.5-83.5) and the mean pre-restoration RFA was 76.9 (68.5-85). The mean RFA difference between baseline and pre-restoration was +4.3 ISQ (-8–25). The mean RFA value pre-restoration was significantly higher than the clinically acceptable value of 65 ISQ (p <.001). There was a significant increase in implant stability between baseline and pre-restoration (p=.019). The baseline RFA values were positively correlated with the pre-restoration RFA values (p=.019). Duration did not significantly influence the RFA difference between baseline and pre-restoration (p=.166). Implant length (p=.935) and width (p=.147) were not correlated with RFA difference.
Conclusions: Within the limitations of this study, there is evidence to suggest that implants installed using graftless motor-driven crestal sinus elevation achieved clinically acceptable stability as represented by RFA values. Implants stability increased after surgery however duration of healing after the mean healing time in this study did not impact the RFA difference. Furthermore, implant length and width did not influence RFA values measured.