Dental implant placement to support fixed and removable prosthesis has become a routine procedure with predictable out comes in the new era of dentistry. There are number of factors affecting the success rate of implants. Some are considered biological/anatomical factors like the amount of bone, bone density, implant angulation where some are called biomechanical, mostly related to the length, diameter and design of implant.
Design of implant platform, the coronal part of actual implant connecting to the implant abutment, is an important part when the masticatory loads transferred to implant body and ultimately to the surrounding bone. Failure to design this part can result in rotational movements of prosthesis, Implant fracture or bone loss. In most cases, Peri-implant bone loss is expected to occur after implant insertion (0.9 mm in the first year and 0.1 mm subsequently).1 But when the implant is loaded, 1.5 to 2 mm of bone loss is observed.2
In comparing Implants to natural tooth, lack of biological width, lack of periodontal tissue, presence of gap between implant any prosthetic abutment and location on fulcrum on the bone crest can increase inflammation on crestal bone causing bone loss. Additionally, excursion, lateral and rotational forces may cause abutment instability, in which can be reduced by considering the platform design.
As one of the earliest platform designs, external hexagon was implemented to rotation of abutment and to facilitate insertion of abutment. Due to reduced hexagon size, this system is showing some micromovements. This results in the evidence of some gaps which increase the chance of bone resorption. For this reason, this is not a system of choice in the overloaded cases.3
In contrast to external hexagon, internal hexagon creats a better distribution of stress around the implant and a reduced amount of stress around crestal bone. This is due to tapered shape of the hexagon socket and also transferring fulcrum to the more apically position away fronm crestal bone.This system is advantageous when immediate loading of implant is required.
In this system, the abutment is joined to the implant through an internal taper connection without a retention screw. This connection locks the system because of the mechanical friction between the external wall of the abutment and internal wall of the implant, and no rotation of the abutment is observed.4 In the Morse cone connection, the screw junction is more resistant than that from the external hexagon, because the junction in the former is deeper and has internal walls with a convergent angle from 8 to 11 degrees. The internal wall of the implant supports the abutment and decreases the stress. As a result, 30% of higher force is necessary to disassemble the retention screw when compared with force is necessary to assemble it.5,6,7.
This system consists of the placement of smaller-diameter prosthetic components on wider-diameter implants which improves the stress distribution and decreases the peri-implant bone loss. It also promote more soft tissue coverage around the neck of implant which provide better seal, increase biological width and improve the esthetic. The use of this system is advantageous in esthetic zone when the papillary preservation is a must.7
There are many researches to improve bio mechanic and bio compatibility of dental implants. In term of implant platform, one that can be develop is to combining different system to achieve a better one. Using platform switching with a modified “deep” morse cone can improve esthetic and at the same time transfer fulcrum to the mid-section of implant body and away from crestal bone, close to where fulcrum in natural tooth locates.
1. Goodacre CJ, Bernal G, Rungcharassaeng K, et al. Clinical complications with implants and prostheses. Prosthet Dent 2003;90:121Y132
2. Lo´pez-Marı´ L, Calvo-Guirado JL, Martı´n-Castellote B, et al. Implant platform switching concept: an update review. Med Oral Patol Oral Cir Bucal 2009;14:450Y454
3. Maeda Y, Satoh T, Sogo M. In vitro differences of stress concentrations for internal and external hex implant-abutment connections: a short communication. Oral Rehabil 2006;33:75Y78
4. Salvi GE, Lang NP. Changing paradigms in implant dentistry. Crit Rev Oral Biol Med 2001;12:262Y272
5. Hunt PR, Gartner JL, Norkin FJ. Choice of a dental implant system. Compend Contin Educ Dent 2005;26:239Y248
6. Sutter F, Weber H-P, Sorensen J, et al. The new restorative concept of the ITI dental implants system: design and engineering. Int J Periodontics Restorative Dent 1993;13:408Y431
7. Pita M S, Anchieta R B. Prosthetic Platforms in Implant Dentistry. The J Craniofacial Surgery. 2011;22:20327Y2331