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Comparing Short with Long Implants with Grafting

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This content is based on the article "Short Implants An Answer to a Challenging Dilemma?" published in Dental Clinics of North America (April 2020)

Over the years, multiple studies have been published using an intrabony implant length of 8 mm or less as the definition of a short dental implant and has been gaining acceptance worldwide.

  • The article reviews the efficacy of using the currently available short implants with enhanced macrosurface and microsurface technology and abutment interfaces allowing their placement in cases previously thought ill-advised.
  • This allows implant treatment in a potentially faster, less expensive, less complicated manner, with decreased morbidity and comparable success rates with long/standard length implants with concomitant bone augmentation procedures.
  • Short implants (<8 mm) have been promoted as a treatment option in many clinical scenarios with limited bone volume where long/standard length implants were otherwise contraindicated if not for complex, sophisticated and costly bone augmentation procedures that would have been required.

Studies Comparing Short Implants with Long Implants with Grafting

Posterior Maxilla

A randomized controlled multicenter study comparing 6-mm implants with 11- to 15-mm implants with sinus graft procedures found equal success at 1-year after loading. However, the 6-mm implant group had a substantially shorter surgical time and cost less than 50% as the long implant plus graft group.

A similar study, using the same 6-mm (short) and 11- to 13-mm (long) implants found that short implants can be used successfully in the posterior maxilla and that they decrease the need for complicated adjunctive procedures, thereby decreasing patient postoperative pain and morbidity.

The European Academy of Osseointegration Consensus Conference found predictably high implant survival for both short implants and long implants with their corresponding sinus grafting procedures. However, given the added number of biological complications, and the increased cost, surgical time, and morbidity associated with longer implants in grafted sinuses, “shorter implants may represent the preferred alternative.”

A systematic review concluded that there was no difference in the survival rate between short (5–8 mm) implants and long (>8 mm) implants with simultaneous lateral window sinus grafts. Complication rates, cost and operating time were all less compared with short implants.

Another systematic review of 3 randomized controlled trials comparing short (≤8 mm) with long (≥8 mm) implants with lateral window maxillary sinus grafts with follow-up periods for at least 3 years found no significant difference between the 2 techniques in regards to implant survival, marginal bone loss and patient satisfaction.

Posterior Mandible

A systematic review that included 4 articles, comparing long implants placed in vertically augmented bone with short implants in native non-augmented sites, concluded that the implant and prosthetic survival rates were comparable for both techniques. Nonetheless vertical augmentation using interpositional inlay block grafts is costlier, lengthens treatment time and increases complications.

A meta-analysis using 4 studies, evaluating long (>8 mm) implants with various vertical augmentation techniques with short (≤8 mm) dental implants in ungrafted bone with at least 1 year of follow-up after final prosthesis insertion, found a 97% versus 92.6% implant survival rate for short and long implants with grafting, respectively. Moreover, there was an increased trend of complications with bone augmentation procedures and long implants. They determined, owing to the decreased incidence of surgical complications, that short implants should be preferred when adequate bone is present.

A 5-year retrospective study comparing clinical and radiographic findings comparing short (6 mm) and standard (9 mm) length implants that were placed after vertical ridge augmentation with autogenous bone blocks. Although there were no statistically significant differences in the number of implant or prostheses failures, prosthetic or biological complications, the number of surgical complications was greater in the standard length implants with augmentation. Plus, the short implants had statistically significant less marginal bone loss than the long implants.

A randomized controlled trial comparing 5-mm length (short) implants with 10-mm length (standard) implants placed in sites augmented with anorganic bovine xenograft bone blocks using the interpositional vertical grafting technique. They found no statistically significant differences in implant or prosthetic failures or biological or prosthetic complications. There was a statistically significant difference in marginal bone loss over the 5-year study, with short implants loosing less bone than the standard length implants. The conclusion was that both techniques provided acceptable results up to 5 years, but that treatment with short implants less costly and quicker.

We hope you you find the conversation interesting and helpful. We always look forward to hearing your thoughts and receiving your questions and/or suggestions about this post and other topics. Leave a comment in the box below or send us your feedback by email.

Until next time!
CDA Oasis Team

2 Comments

  1. Murray Arlin March 12, 2020

    readily available references would be good including some studies that have shown a higher failure rate with lengths of 6 mm and shorter compared to longer implants.

    Reply
  2. Murray Arlin March 12, 2020

    In the studies quoted one should note that the comparisons of the short implants to the longer implants were limited to longer implants placed in association with various grafting procedures. The comparison of these 2 clinical situations is a fair reflection of the clinical choices one may have, and based on the included studies described one would conclude that one may expect equivalent implant survival rates comparing these 2 approaches.

    However one should NOT extrapolate that short implants should be expected to have equivalent survival or success rates to longer implants in general i.e. longer implants placed in pristine bone. In fact several studies and my own clinical research has shown roughly double the long-term failure rate comparing implants of 6.0mm or shorter length compared to 8.0mm or longer i.e. about 90% v.s.95%.

    So in summary, when confronted with a patient with limited bone in the vertical dimension, short implants may be a simpler approach with similar results compared to augmentation and longer implants. However I would suggest that very short implants (6.0mm or shorter) should be expected to have a higher long-term failure rate v.s. longer implants placed in pristine bone.

    Reply

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