ショートインプラントの上部構造体装着後の調査

抄録

Background: Bone augmentation treatment with bone grafts or sinus lift may be indicated for implant therapy in patients with insufficient bone height of the posterior. However, these procedures require invasive surgery and long healing times. Although the insertion of short implants is sometimes recommended in such cases, there has been no detailed study on the placement and prospect of short implants in Japan. Therefore, the purpose of this study was to assess the survival rate of short implants placed in the posterior region.
Methods: From April 1997 to March 2006, a total of 86 short implants with a diameter of 4.1 or 5.0 mm and length of 7.0 mm were placed in 43 patients with insufficient bone height of the posterior after connecting the superstructure. The follow-up period ranged from April 1997 to March 2011 (mean: 89.4±35.9 months). To elucidate the difference between successful and failed implants, we investigated the effect of such factors as bone quality (TypeⅠ to Ⅳ), implant location (first premolar, second premolar, first molar and second molar region), implant diameter (4.1 or 5.0 mm), type of superstructure (splinting or non-splinting) and crown-to-implant ratio.
Results: The overall survival rate of the 86 implants was 95.3%. The 46 implants in the posterior maxilla exhibited a survival rate of 95.7%, while the survival rate for the 40 implants in the posterior mandible was 95.0%. A total of 4 out of 86 implants were lost during the observation period. The bone quality and type of superstructure might not affect the implant survival rate. However, implants inserted at the distal end and those with large crown-to-implant ratios might exhibit a decreased survival rate.
Conclusion: Short implants could be used in cases of insufficient bone height of the posterior maxilla and mandible. However, consideration should be given to the clinical outcomes associated with the implant location, crown-to-implant ratio and preservation of mucosa.