Clinical outcomes of 6-mm implants compared with 10-mm implants in Japanese patients: A retrospective study

Objective

This study aimed to compare the clinical outcomes of 6-mm implants with those of 10-mm implants in Japanese patients, particularly on cumulative survival rates and associated risk factors.

Methods

This study included patients from Tokyo Dental College Suidobashi Hospital who received 6-mm implants from January 2014 to August 2020 and 10-mm implants from January 2014 to December 2016. Data collection continued until August 2021. Patient demographics, implant locations, implant widths, cumulative survival rates, and conditions of lost implants were also analyzed.

Results

A total of 69 patients received 95 6-mm implants, and 416 patients received 607 10-mm implants. The cumulative survival rate up to 7 years was 94.0 % for patients who received 6-mm implants and 98.8 % for patients who received 10-mm implants, indicating a significantly lower survival rate for patients with shorter implants. The hazard ratio for implant loss was 4.07, indicating a higher risk among patients with 6-mm implants. Most failures in the 6-mm implant group occurred postprosthetic placement, particularly in the maxillary molar region, whereas most 10-mm implant losses occurred prerestoration.

Conclusions

Although 6-mm implants have a slightly lower cumulative survival rate compared with 10-mm implants, they are a viable alternative to bone augmentation. Therefore, careful consideration of patient-specific factors such as bone quality and occlusal forces is crucial, particularly in the maxillary molar region. Furthermore, long-term studies and investigation of the risk factors are necessary to optimize treatment planning for short implants.