Implant positioning when replacing the four maxillary incisors: a platform-switched treatment option

Patients do not view dental implants as an object of desire but seek a way to replace teeth that will be as cost-effective and minimally traumatic as possible. Nowadays, anterior fixed partial dentures can provide an esthetic result that is difficult to distinguish from the natural dentition. Consequently, any implant-supported prosthesis will be compared to the esthetic and functional standards set by conventional tooth-supported restorations. The restoration of the four maxillary incisors by means of an implant-supported prosthesis is one of the most challenging situations in implant dentistry. The questions of how many implants should be placed and where they should be positioned are especially important for achieving a superior end result. This article proposes and describes the placement of two platform-switched implants in the central incisor positions as a means of achieving the correct biomechanical behavior of the prosthesis, along with the best possible esthetic results.

Biomechanical repercussions of bone resorption related to biologic width: a finite element analysis of three implant-abutment configurations

Most biomechanical studies of implant-supported restorations have not taken into account the biologic changes that occur following exposure of the implants to the oral environment. Therefore, the present finite element analysis study was designed to compare the biomechanical response of three types of implant-abutment configurations both before and after establishment of a new biologic width. The three functional units studied were: a 5-mm implant platform connected with an external hexagon to a 5-mm-diameter abutment (type 1), a 5-mm implant platform connected with an external hexagon to a 4.1-mm-diameter abutment (type 2), and a 4.8-mm implant platform connected with an internal hexagon to a 4.1-mm-diameter abutment (type 3). The type 3 design, which combined platform switching with an internal connection, exhibited the smallest distortions in stress distribution after bone modeling, and the stress was distributed over the entire contact surface most smoothly and uniformly. Bone resorption following creation of the biologic width changes the biomechanical behavior of a restoration. In this study, the two implant-abutment designs featuring a smaller-diameter abutment on a larger-diameter implant platform achieved better results than the implant featuring the same-diameter implant platform and abutment, even though their initial bio?mechanical load potential was lower. (Int J Periodontics Restorative Dent 2009;29:479-487.).

The effect of interimplant distance on the height of the interimplant bone crest when using platform-switched implants

A distance of more than 3 mm between two adjacent standard implants has been shown to preserve the interproximal bone peak, resulting in only 0.45 mm of resorption. The purpose of this study was to determine whether use of the platform-switching technique would change the bone resorption patterns between adjacent implants placed less than 3 mm apart. Radiographic studies of bone resorption around 41 pairs of implants placed less than 3 mm apart in 37 patients were carried out. Mean vertical bone resorption was 0.62 mm, and the mean horizontal component was 0.60 mm. The bone peak that extended coronally beyond an imaginary line connecting the two implant-abutment interfaces was measured, and the mean bone height preservation above this interimplant line was 0.24 mm.

Benefits of an Implant Platform Modification Technique to Reduce Crestal Bone Resorption

PURPOSE

The alveolar bone resorption that occurs around a 2-piece implant following abutment attachment is a well-documented observation. Several investigators propose that crestal bone loss is a response to the invasion of the biologic width by secondary bacterial colonization and micromovements at the implant-abutment interface. This study proposes the creation of a difference between the diameter of the implant platform and diameter of the abutment (implant platform modification), shifting the implant-abutment interface medially to minimize invasion of the biologic width.

MATERIAL AND METHODS

We present a series of 30 control cases and 30 study cases using the platform-modification technique. Interproximal bone resorption on the medial and distal of each implant was assessed using digital radiography at 1, 4, and 6 months after abutment attachment.

RESULTS

The mean value of bone resorption observed in the mesial measurement for the control group was 2.53 mm, whereas for those patients included in the study group, it was 0.76 mm. The mean value of bone resorption observed in the distal measurement for patients in the control group was 2.56 mm, whereas for those included in the study group, it was 0.77 mm.

CONCLUSIONS

All patients in the study group had a significant reduction of bone loss in comparison to the control group (P < 0.0005).