Does implant site preparation technique affect ISQ trends, bone loss for varying implant lengths?

Abstract

Background Bone expansion has been used for implant site preparation in the posterior maxilla as it involves compression of trabecular bone thereby enhancing bone-to-implant contact and primary implant stability. This study used a split mouth design to compare conventional drilling and bone expansion techniques by evaluating the ISQ trends upto implant loading and progressive crestal bone loss. It also analyzed the effect of these techniques when implants of different lengths were used. Aim/Hypothesis (a) Which of the 2 site preparation techniques-Conventional drilling or bone expansion showed favorable initial and progressive ISQ trends and minimal bone loss. (b) Which of the above mentioned techniques performed better when implants of different length were placed. Material and Methods 30 patients who required replacement of a single tooth bilaterally in the posterior maxilla were recruited. In all, 60 implant sites were assessed for bone density by undergoing Cone Beam Computed tomography. Using random allocation, each patient received an implant using drilling protocol (Control site) on one side and using expansion technique on the contralateral side (Test site). The implants placed in the Control and Test site were of the same brand, length and diameter. After a load free healing period of 3 months, the implants were restored using screw retained porcelain-fused to metal restorations. The following parameters were evaluated- (a) Implant Stability Quotient (ISQ) values -ISQ at implant placement (ISQi) and at commencement of functional loading (ISQf) was recorded using Osstell ISQ. (b) Crestal bone loss. - Periapical radiographs were taken immediately after implant placement and at the time of placement of the definitive restoration. Results A highly statistically significant difference was noted between the Test and the Control group when ISQi , ISQf and Crestal bone loss were compared. For implants of length > 10 mm, the Test group presented with statistically significant higher mean ISQi & ISQf (59.76 ± 4.33 & 62.56 ± 4.08) values in comparison to Control group (55.46 ± 3.66 & 58.60 ± 4.01). A statistically significant higher mean crestal bone loss was noted in the Control group (−0.37 mm ± 0.09 mm) as compared to the Test group (−0.19 mm ± .06 mm). For implants <10 mm in length, a higher (not significant) mean ISQi & ISQf (62.23 ± 2.38 & 65.60 ± 2.72 ) values were noted for the Test group in comparison to Control group (60.56 ± 4.12 & 64.05 ± 4.01). A higher (not significant) mean crestal bone loss was noted in the Test group (−0.32 mm ± 0.09 mm) as compared to Control group (−0.30 mm ± 0.14 mm). Conclusions and Clinical Implications The bone expansion technique resulted in higher initial and final ISQ values, lesser bone loss compared to the conventional drilling technique in the posterior maxilla. When implants longer than 10 mm were used, bone expansion technique showed a more favorable ISQ trends and reduced bone loss.