Implant therapy has substantially changed in the past decades from indications for fully edentulous patients to single-tooth sites. In addition, implant dimensions in terms of length and diameter changed and further increased the spectrum of indications. Based on 124 partially edentulous patients treated in same University setting, the mean implant length gradually changed from 12 mm (implants placed between 2002 and 2005; Gamper et al., 2017) to 10 mm (implants placed in 2009; Ebler, Ioannidis, Jung, Hammerle, & Thoma, 2016) within 5 years.

Aim: To compare the implant survival rate between short dental implants and standard-length implants placed in combination with bone grafting at 5 years of loading. 

Methods: This multicentre study enrolled 101 patients (137 implants) with a posterior maxillary bone height of 5–7 mm. Patients randomly received either short implants (6 mm; GS) or long implants (11–15 mm) with sinus grafting (GG). Six months later, implants were loaded with single crowns and patients re-examined at 1, 3 and 5 years of loading. Outcomes included: implant survival, marginal bone levels (MBLs), biological and technical parameters and patient-reported outcome measures (OHIP49 = Oral Health Impact Profile). Statistical analysis was performed using a nonparametric approach. 

Results: This multi-centre randomized controlled clinical trial demonstrated no differences between the two treatments based on implant survival rates, marginal bone levels, marginal bone level changes, patient-reported outcome measures as well as biological and technical outcomes 5 years after placement of final reconstructions.  At 5 years, 90 patients (124 implants; GS: 60; GG: 64) were re-examined (drop-out rate 10%). Patient-level implant survival rates were 98.5% (GS; 1 implant failure) and 100% (GG; p = 0.49). Mean MBLs were 0.54 mm ± 0.87 (GS) and 0.46 mm ± 1.00 (GG; p = 0.34). Biological and technical parameters were not significantly different (p > 0.05). Median overall OHIP-49 scores improved significantly up to 5 years in both groups (GS: p = 0.03; GG: p = 0.00; intergroup comparison p = 0.11). 

Conclusions: Both treatment modalities can be considered suitable for implant therapy in the atrophied posterior maxilla rendering no differences in terms of survival rates, marginal bone levels (changes), patientreported outcome measures as well as technical and biological complications up to 5 years following loading with final single-tooth implant-borne reconstructions.

References 

Albrektsson, T., Zarb, G., Worthington, P., & Eriksson, A. R. (1986). The long-term efficacy of currently used dental implants: A review and proposed criteria of success. International Journal of Oral and Maxillofacial Implants, 1, 11–25.

Bechara, S., Kubilius, R., Veronesi, G., Pires, J. T., Shibli, J. A., & Mangano, F. G. (2017). Short (6-mm) dental implants versus sinus floor elevation and placement of longer (>/=10-mm) dental implants: A randomized controlled trial with a 3-year follow-up. Clinical Oral Implants Research, 28, 1097–1107. https://doi. org/10.1111/clr.12923

Quaranta, A., Piemontese, M., Rappelli, G., Sammartino, G., & Procaccini, M. (2014). Technical and biological complications related to crown to implant ratio: A systematic review. Implant Dentistry, 23, 180–187. https://doi.org/10.1097/ID.0000000000000026

Wallace, S. S., Tarnow, D. P., Froum, S. J., Cho, S. C., Zadeh, H. H., Stoupel, J., … Testori, T. (2012). Maxillary sinus elevation by lateral window approach: Evolution of technology and technique. The Journal of Evidence-based Dental Practice, 12, 161–171. https://doi.org/10.1016/ S1532-3382(12)70030-1