Short and reduced diameter implants
There is currently a global trend towards the use of minimally invasive procedures, and it is perhaps the most discussed topic in the field of implant dentistry.
In cases where limited bone is available (both in terms of width and depth), there is the option of using short and small-diameter implants instead of bone augmentation, which are associated with morbidity and potential risk of complications.
In the 1st EAO Consensus Conference in 2006, short implants were defined as a device with a designed intra bony length of ≦ 8mm and narrow implants as one in which the stated diameter was ≦ 3.5mm (Renouard & Nisand. 2006). It was also pointed out that short and narrow implants are mostly used in cases involving reduced bone volume and must therefore be compared to standard implants associated with bone augmentation procedures.
“Bone augmentation was associated with greater morbidity than short and narrow implants.”
Where are we now?
The most recent systematic reviews comparing short implants with standard implants plus bone augmentation (Nielsen et al. 2018; Pommer et al. 2016; Tolentino et al. 2018; Palacios et al. 2017; Dias et al. 2018; Starch-Jensen et al. 2017; Uehara et al. 2018; Rokn et al. 2018) had the following conclusions:
- implant and reconstruction survival rates are similar in both options
- short implants have favourable treatment time, cost, morbidity and patient-related outcomes
However, more long-term follow-up clinical studies are needed (ten years post-loading). Further investigation of the impact of implant diameter and the design of prosthetic reconstructions on the survival rate is also recommended.
“Short implants have favourable treatment time, cost, morbidity and patient-related outcomes”
Although several clinical studies have used narrow-diameter implants in almost all clinical scenarios, RCTs comparing them with standard implants (plus lateral bone augmentation) are still lacking.
As a consequence, there is currently insufficient evidence-based information and clinical recommendations for the indication of narrow-diameter implants in posterior zones with reduced bone volume.
“However, more long-term follow-up clinical studies are needed”
Compared to standard implants, short and narrow-diameter implants seem to behave similarly regarding peri-implantitis and prosthetic complications. On the other hand, very scarce data is available regarding the behaviour of implants placed in augmented bone with respect to peri-implantitis.
The key factors for preventing biological complications are: prosthetically driven implant placement, and soft tissue management to ensure adequate thickness of keratinised tissue.