Spline™ Implant Prospective Multicenter Study: Interim Report on Prosthetic Screw Stability in Partially Edentulous Patients

Abstract

Loosening of implant abutment and prosthesis screws during functional loading is an industry-wide phenomenon that is especially well documented with the external hexagon implant connection. Although numerous efforts to reduce or eliminate screw loosening have been attempted, the problem still persists, especially with implant restorations in the partially edentulous patient. In 1992, the spline was developed as an alternative to the external hexagon implant-abutment connection. A prospective multicenter study was begun in 1996 to evaluate the abutment and prosthesis screw joint stability of Spline dental implants (Centerpulse Dental Division, Carlsbad, California) over 5 years of post-loading clinical follow-up. From October 1996 to December 2000, 73 partially edentulous patients were consecutively treated with 113 Spline implants placed in two private dental practices. Three patients with 1 implant each withdrew from the study for various reasons; of the remaining 110 implants in 70 patients who continued in the study, 82% (n = 90) were placed between 1997 and 1998. No cases of abutment or prosthesis screw loosening occurred with up to 54 months (mean = 38.95 mo; range, 3-54 mo; mode, 20 mo) of post-loading clinical follow-up. These interim findings of the ongoing study suggest that Spline dental implants may provide a stable prosthetic connection in partially edentulous cases during short-term clinical follow-up.

Screw Loosening for Standard and Wide Diameter Implants in Partially Edentulous Cases: 3- to 7-Year Longitudinal Data

“…12 It has also been suggested by manufacturers that the use of torque drivers should minimize or prevent this screw loosening. Vogel and Davliakos 13 have recently reported that there was no screw loosening from 3 to 54 months when the Spline implant and prosthetic components (Centerpulse Dental Division, Carisbad, CA) were used. The purpose of this prospective study was to longitudinally compare the frequency of screw loosening in standard diameter, (3.75 and 4.0 mm) implant prostheses to that of wide diameter, (5.0 and 6.0 mm) implant prostheses that have been hand torqued, and to see if using a torque driver could prevent, or minimize, the reoccurrence of this loosening.…”

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“…However, growth in reception and subsequent demand of dental implant phenomena have put forth considerations for shorter healing periods and better esthetics in last the decade or two [6,7]. Therefore, 1P system is returning to the spotlight only after many studies [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] found 1P and immediate loading implants superior in terms of implant-bone interface (IBI), surgical protocol, and elimination of potential structural drawbacks of 2P implant in two-stage protocol. Regardless of the piece-count, primary stability and long-term success is the driving force behind the dramatic evolution of the implant design.…”

Abutment rotational freedom on five implant systems with different internal connections

“…7 Before tightening the abutment screw, an abutment can be partially rotated back and forth in horizontal micromovements within the dimensions of the interfacial void between the antirotational elements. 8 This phenomenon corresponds to rotational freedom, leading to horizontal misfit, and has mainly been studied for external connections. [9][10][11][12][13][14][15][16][17][18][19] A linear correlation has been reported between the rotational freedom and screw loosening with such connections.…”

“…Long-term clinical data and in vitro mechanical evaluations have demonstrated that, although external hexagon implant-abutment connections are more susceptible to abutment screw loosening and fracture than implants with internal connections, the same problems can occur with any screw-retained abutment and prosthesis. 8,[20][21][22][23][24][25][26] Rotational displacement of the abutment influences the fit of the prosthetic superstructure compared with the neighboring teeth, antagonist dentition, and periodontium and may adversely affect prosthesis insertion if the abutments are angled. 27 Errors in the rotational positioning of components can result in the need to adjust proximal contacts chairside.…”