Influence of Connection Types and Implant Number on the Biomechanical Behavior of Mandibular Full-Arch Rehabilitation

Abstract

To evaluate the influence of different implant numbers and connection types on the biomechanical behavior of mandibular full-arch implant-supported rehabilitation. Materials and Methods: Computed tomography-based finite element models comprising a totally edentulous mandible and 3.8 × 13-mmdiameter implants, abutments, abutment screws, bar retaining screw, and bar were constructed. Different implant numbers (three, four, and five implants) and loading conditions (symmetrical/balanced, unilateral, and posterior with diverse loading magnitudes) were simulated for both external hex and Morse-taper connections. The peak equivalent strain (EQV strain) in the bone and the peak of von Mises stress (EQV stress) in the abutment screw and bar retaining screw were evaluated. Results: Lower strain values were observed for a symmetrical loading distribution. Considering the same loading conditions, significantly higher bone strain levels were observed for external hex, compared with the Morse-taper connection. The number of implants had no significant influence on strain levels in bone, irrespective of the connection types. Compared with the external hex connection, the Morse-taper connection type presented significantly lower EQV stress values in abutment screws, but significantly higher stress in the bar retaining screw. Increasing the number of implants significantly reduced the EQV stress in the abutment screw and bar retaining screw. Conclusion: The Morse-taper connection type significantly decreased the strain levels in peri-implant bone, while increasing the stress in bar retaining screws. A smaller number of implants in an inferior full-arch rehabilitation slightly increased the stress in the abutment and bar retaining screws. Balanced adjustments of the loading improve the biomechanics of a mandibular full-arch rehabilitation.

Clinical Behavior and Complications of Mandibular Full-Arch Fixed Dental Prostheses Supported by Three Dental Implants. A Systematic Review and Meta-Analysis

“…Rehabilitation of the edentulous mandible with three implants can reduce the economic costs of surgical and prosthetic phases, and so make treatment more acceptable to the patient [19]. Notwithstanding, and according to scientific literature, the number of implants have effect on the peri-implant stress distribution, reporting that a lower number of implants can slightly increase the stress in abutment and screws [17,18]. However, and taking into account the obtained results, the use of three dental implants for mandibular full-arch fixed dental prostheses showed similar outcomes and complication rates in comparison with mandibular ISFCDP on more than three implants [30][31][32][33].…”

“…Despite the advantages described in the literature [17,18], this treatment modality requires specific conditions and rigid clinical characteristics [19,20]. In this sense, anatomical conditions play an important role due to the location and characteristics of the implants used, since in many cases, these patients present limited ridges with deep concavities in the anterior mandible [19,20].…”

“…In this sense, anatomical conditions play an important role due to the location and characteristics of the implants used, since in many cases, these patients present limited ridges with deep concavities in the anterior mandible [19,20]. Although the number of implants has effect on the peri-implant stress distribution; it has been reported that a lower number of implants can slightly increase the stress in abutment and screws [17,18]; however, the use of frameworks and abutments may compensate these biomechanical weaknesses [17][18][19].…”

Influence of fibromucosa height and loading on the stress distribution of a total prosthesis: a finite element analysis

“…The use of total prostheses for edentulous patients is the treatment of choice to improve masticatory capacity and their oral health, restoring aesthetics, and patient satisfaction in an accessible manner [4][5]. However, adapting the mandibular prosthesis is more difficult than the upper one, since bone remodeling of the lower arch mainly occurs in the vertical direction, thus hindering functioning of the prosthesis that rests on the residual border [6]. A suitable occlusal surface is necessary in order to obtain good prosthesis retention and stability, as well as to prepare occlusal adjustments that correctly guide the masticatory loads [7].…”

“…There are several forms of occlusion in edentulous patients, in which bilateral balanced occlusion is the most used, and seeks to provide better mastigatory performance and improve the patient quality of life [8][9]. Excursive movements are avoided as in the anterior guidance, in which the posterior teeth perform horizontal excursive movements and vertical overlap of the jaw [9][10]; as well as, the unilateral loadings, where the teeth are contacted in a disocclusion pattern reducing the stability [6].…”