Long term bone level stability on Short Implants: A radiographic follow up study

Objectives: Placement of short endosseous implants represents a valid treatment in the setting of limited alveolar bone height. This study’s objectives were: to estimate the 5 year clinical survival of BiconTM short implant and to evaluate radiographic bone level changes around 6 x 5.7mm implants in comparison with longer non-6 x 5.7mm implants. Methods: A retrospective cohort study design was used. The cohort was composed of patients who had at least one 6 x 5.7mm implant placed for 5 years, at least one non 6 x 5.7mm implant, and who were willing to return to the dental office for radiographic evaluation. A total of 62 implants, 28 6 x 5.7mm (test group=short implant) and 34 non 6 x 5.7mm (control group=non short implant), were placed in 20 patients (12 males and 8 females). Mean length of non 6 x 5.7mm implants was 9.7 mm, ranging from 8mm to 14mm, while mean diameter was 4.30 mm (range: 3.5 to 5 mm). Bone loss, defined as the vertical difference in crestal bone level measurements, from the baseline (day of implant placement) to the 5 years follow-up, was digitally determined on periapical radiographs. Generalized linear mixed models were used for the statistical analysis. Result: Five years survival rates for test and control groups were 100.0% and 96.8% respectively, but this difference was marginally not statistically significant (p=0.35). There was no significant difference between the two groups with regard to mean changes of radiographic bone levels. Conclusion: Short implants with large diameter (6 x 5.7mm) have a long-term (>5-years) survival rate and crestal bone level maintenance similar to that observed for non 6 x 5.7mm implants. The results of this radiographic study support the hypothesis that 6 x 5.7mm implants can be successfully used in edentulous maxillary and mandibular areas with limited bone height.