The effects of off-axial loading on peri-implant marginal bone loss in a single implant : a 1-year retrospective study after loading

Abstract

The aim of this study was to evaluate the influence of crown width/fixture width ratioon crestal bone loss around Astra single dental implants placed in the first molar area.Forty-four subjects (19 males and 25 females; age range: 25 to 75 years; mean age: 54years) were selected from patients who were treated with single-tooth implants betweenMarch 2001 and December 2009 at the Department of Periodontology, Gangnam Severance Dental Hospital.The marginal bone level change and gingival parameters (modified plaque index andmodified sulcus bleeding index) of the peri-implant soft tissue were assessed one yearafter functional loading. The perpendicular distances from the center of each fixture tothe most distal (dW) and most mesial (mW) were measured in the periapical radiographicview (Cr = mW + dW, Cr’ = mW or dW , I=fixture width, I’=fixture width/2).Pearson correlation analysis was used to determine the correlation between crownwidth/fixture width ratio and crestal bone loss; no statistically significant relationshipwas found between crown width/fixture width ratio and 1-year bone level change(p=0.156).No statistically significant differences in marginal bone level change were foundbetween axial and non-axial loading implants (Mann-Whitney U-test ; p=0.57).The bone level change at the surface adjacent and distant to the cantilever werecompared to determine the cantilever effect on the marginal bone loss. Bone level changefor the surface adjacent and distant to the cantilever was not statistically significant(Wilcoxon’s signed rank test; p=0.08).Peri-implant soft tissues were clinically healthy and revealed low modified plaque index(mPI) and modified sulcus bleeding index (mSBI).From this study, it may be concluded that off-axial loading resulting from a high crownwidth/fixture width ratio does not increase the risk for peri-implant marginal bone lossduring functional loading.