Whether crown-to-root ratio is critical when it comes to dental implants is debatable; a more relevant topic regarding implant integration and survivability is the crown to surface area. Moreover, many clinical studies that compare implants in grafted sites versus short implants fail to address biting force, lateral excursion, and parafunctional habits of the patient. Biting force is a critical factor in determining the length of dental implants in the anterior region and the diameter of implants in the posterior. Since “form follows function,” patients with heavy biting force present with a mandibular plane angle (GoGn-SN) of less than 27 degrees (brachy-facial) with a heavy antegonial notch. This heavy bite presents with deep bite, limited interocclusal spaces, exostosis, flat cusps, and group function. Therefore, it is crucial to have long dental implants in the anterior to resist lateral force and wide-diameter implants in the posterior region.
These heavy biters often present with both a wide and denser quality of bone. Presence of canine guidance is critical for the survival of short implants, as they do not handle lateral excursive forces well. Reduction of cusp angles and flattening of both curves of Spee and Wilson allow the clinician control over the occlusal scheme. Finally, parafunctional habits of the patient should be considered. Shorts implants will not perform well in lateral bruxers. Protective occlusal schemes and nightguards are highly indicated for these patients.
In summary, I am not against wide-diameter (5 mm to 7 mm) short-length (5 mm to 6 mm) dental implants. Regular-diameter (4 mm) short-length (5 mm to 6 mm) implants need to show longer survival data in studies. A minimum 10-year success rate rather than survival rate should be guaranteed in private practice to satisfy patients. Short implants are a minimally invasive approach for patients with a compromised health status who have a favorable occlusal scheme (ie, canine guidance, flat cusp angles, GoGn-SN >37 degrees, and no parafunction). However, sinus lifts can now be performed relatively easily due to new, innovative sinus tools, resulting in decreased morbidity. Today’s sinus lift/augmentation techniques are minimally invasive and highly predictable, and can be learned easily (through educational organizations such as International Academy of Dental Implantology, www.ce4dentist.com).
About the Authors
Barry Levin, DMD, PC
American Board of Periodontology
Clinical Associate Professor
Department of Periodontics
University of Pennsylvania School of Dental Medicine
Private Practice limited to Periodontics and Implant Surgery
Barry Wagenberg, DMD
Director of Dental Education and Periodontics
Newark Beth Israel Department of Dentistry
Associate Clinical Professor Department of Periodontics and Implant Dentistry
New York University School of Dentistry
Livingston and Roselle Park, New Jersey
Samuel Lee, DDS, DMSc
International Academy of Dental Implantology
American Board of Oral Implantology/Implant Dentistry
Private Practice limited to Periodontics and Implant Dentistry
San Diego, California
Inventor of the crestal window sinus grafting technique
1. Valentini P, Abensur DJ. Maxillary sinus grafting with anorganic bovine bone: a clinical report of long-term results. Int J Oral Maxillofac Implants. 2003;18(4):556-560.
2. Yildirim M, Spiekermann H, Biesterfeld S, Edelhoff D. Maxillary sinus augmentation using xenogenic bone substitute material Bio-Oss in combination with venous blood. A histologic and histomorphometric study in humans. Clin Oral Implants Res. 2000;11(3):217-229.
3. Schincaglia GP, Thoma DS, Haas R, et al. Randomized controlled multicenter study comparing short dental implants (6 mm) versus longer dental implants (11-15 mm) in combination with sinus floor elevation procedures. Part 2: clinical and radiographic outcomes at 1 year of loading. J Clin Periodontol. 2015;42(11):1042-1051.
4. Renouard F, Nisand D. Short implants in the severely resorbed maxilla: a 2-year retrospective clinical study. Clin Implant Dent Relat Res. 2005; 7 suppl 1:S104-S110.
5. Felice P, Cannizzaro G, Barausse C, et al. Short implants versus longer im-plants in vertically augmented posterior mandibles: a randomised controlled trial with 5-year after loading follow-up. Eur J Oral Implantol. 2014;7(4):359-369.
6. Beumer J III, Faulkner RF, Shah KC, Moy PK. Fundamentals of Implant Dentistry, Volume 1: Prosthodontic Principles. Hanover Park, IL: Quintessence Publishing Co., Inc.; 2015.
7. Misch CE. Contemporary Implant Dentistry. 3rd ed. St. Louis, MO: Mosby Elsevier; 2008.