Magnitude and distribution of occlusal forces on oral implants supporting fixed prostheses: an in vivo study

Abstract

Since loading is increasingly believed to be a determining factor in the treatment outcome with oral implants, there is a need to expand the knowledge related to the biomechanics of oral implants. The aim of this study is to gain insight in the distribution and magnitude of occlusal forces on oral implants carrying fixed prostheses. This is done by in vivo quantification and qualification of these forces, which implies that not only the magnitude of the load but also its type (axial force or bending moment) will be registered. A total of 13 patients with an implant supported fixed full prosthesis were selected. Occlusal forces on the supporting implants were quantified and qualified during controlled load application of 50 N on several positions along the occlusal surface of the prostheses and during maximal biting in maximal occlusion by use of strain gauged abutments. The test was conducted when the prostheses were supported by all (5 or 6) implants and was repeated when the prostheses were supported by 4 and by 3 implants only. Despite considerable inter-individual variation, clear differences in implant loading between these test conditions were seen. Loading of the extension parts of the prostheses caused a hinging effect which induced considerable compressive forces on the implants closest to the place of load application and lower compressive or tensile forces on other implants. On average, higher forces were observed with a decreasing number of supporting implants. Bending moments were highest when 3 implants only were used.

Stress analysis of different configurations of 3 implants to support a fixed prosthesis in an edentulous jaw

“…According to Duyck et al, 18 the distal and central implants receive the greatest loads, regardless of the number of implants between them or the total number of implants. Such findings suggest that it is not necessary to use a large number of implants to support a mandibular fixed implantsupported prosthesis.…”

“…The reduction in the number of implants could be a risk factor facilitating screw loosening or fracture. 18 A decrease in the number of implants with maintenance of the implant diameter led to a relevant increase in stress in the prosthetic components. Similar studies evaluating the quantity and arrangement of implants did not evaluate prosthetic components.…”

Prosthodontic Perspective to All- On-4 ® Concept for Dental Implants

“…When a vertical load was applied to the first premolar of the tilted implant, the two neighboring implants mostly shared the load, as the prosthesis was loaded between the mesial and distal implants load was distributed to both supporting implants through the prosthesis, the tilted implant configuration did not show over loading or bending [11].…”

A comparison of the masticatory function between two different types of implant supported prostheses and complete denture for fully edentulous patients

“…3,4 Distribution and magnitude of occlusal forces on implants carrying fixed prostheses was investigated while supported by 5 -6 and 3 -4 implants. 5 Higher forces were observed with a decreasing number of implants.…”

“…6 Regardless of its design, an implant-prosthesis complex transmits occlusal forces to the peri-implant bone. 5 Therefore, the force absorption quotient of the prosthesis material has been a topic of research interest. Skalak 7 envisaged that the use of acrylic resin teeth would be useful for shock protection on implants and recommended the use of acrylic resin as the material of choice for the occlusal surfaces of implant prostheses.…”