The Influence of Crown-to-Implant Ratio on Short Implant Marginal Bone Loss

Purpose: There is a need for more studies evaluating the marginal bone loss (MBL) of rehabilitations in the posterior regions of extremely resorbed maxillae and mandibles supported by short-length dental implants with a high crown/implant ratio (C/I-R). The aim of this study was to evaluate the influence of the C/I-R in implants on MBL considering dental implants with 4 mm of width and 7 mm of length. Materials and Methods: This retrospective cohort study included 59 patients (mean age of 52.8 years) rehabilitated with at least one implant 4 mm in width and 7 mm in length, with an anodically oxidized surface and external connection on the premolar or molar positions, supporting a fixed prosthesis, and in function for a period of 36 months. Periapical radiographs at 36 months were used to calculate the C/I-R and MBL. The Spearman correlation coefficient was used to test the correlation between C/I-R and MBL. The level of significance was set at 5%. Results: One hundred eighteen implants from 59 patients were evaluated. The mean ± SD MBL was 0.67 ± 0.63 mm. The C/I-R mean ± SD was 2.53 ± 0.79 mm. Thirty implants presented a C/I-R ≤ 2, while 88 implants had a C/I-R > 2. A weak nonsignificant inverse correlation (r = -0.081; P = .383, Spearman) was registered between C/I-R and MBL. Conclusion: Within the limitations of this study, it is possible to conclude that implant-supported fixed prostheses with C/I-R > 2 do not correlate positively with MBL. Keywords: crown-to-implant ratio, marginal bone loss, short implant