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Abstract
Today, implant treatment is widely used and the survival rate is high in noncompromised situations. However, there are some scenarios that still remain challenging. One example is the posterior maxilla, where the possibility to place implants can be limited due to reduced bone quality and quantity. Bone grafting is commonly used to increase the bone volume in these situations.
Even if sinus augmentation procedures can offer important benefits such as a high implant success rate, these treatments can be affected by potential surgical complications, i.e. including membrane perforation, damage to the surrounding blood vessels, local infection, post-operative swelling, maxillary sinusitis, and upper lip paresthesia and increased mobidity.
The current literature suggests that placement of short dental implants could be a valid option to grafting procedures especially in the lower jaw. The advantages of using short implants are many; it saves time, lowers the treatment costs and reduces the rehabilitation time, as well as eliminating the complications associated with grafting procedures.
Historically, clinical studies reported on low survival rates for short implants in the maxilla. However, in these studies the surgical procedures utilized short implants with machined surfaces and involved implant placement in restricted anatomic sites with poor bone density. Generally, most implant failures occur in the maxillary molar region, which frequently has poor bone quality.
In order to overcome the limitations presented with extensive bone augmentation and to simplify the clinical procedure, short implants (from 6 to 8mm long) and ultra-short implants (less than 6mm long) were developed but have rarely been used in clinical studies Thus far, a distinctive linear relationship between survival rate and implant length has not been scientifically established. The lack of studies using shorter implants is primarily due to speculation regarding the mechanical nature of shorter implants, such as the concern of an unfavorable crown to implant ratio and the risk of loss of osseointegration due to mechanical overload.
However, despite this speculation, studies have shown that the greater crown to implant ratio of short implants did not result in higher failure rates, greater extent of marginal bone loss, or increased number of biological complications.According to a systematic review by Garaicoa-Pazmiño et al, within the range of 0.6/1 to 2.36/1, the higher the crown-to-implant ratio, the less the peri-implant marginal bone loss will occur. Hence, high crown-to-implant ratio of implantsupported restorations may even provide a protective effect on peri-implant marginal bone level.
