What occlusion and disoclusion standard we should use in complete dentures supported by implants? Literature review

Abstract

In 2000, Becker and Kaiser analyzed the compressive stresses and tensile stresses on implants installed in the edentulous jaws. At first only four implants were used in the mental, pre - foramen, with a bilateral free end with a length of 8 mm. A vertical load of 100 N and horizontal 10 N was applied in distal extensions. The result showed that the first implant suffered compressive tensions, while the second suffered tensile stresses. Increasing the length of the distal extension free for 16 mm, tensions have risen considerably. Prostheses with bilateral free end are acceptable, but may not exceed this length twice the width of premolar teeth. Even with the use of more implants, this length is still an unfavorable condition promoting, maintaining the compressive stress in the distal implant [11]. A model of jaw with implant-supported prosthesis was simulated using the 3D FEM analysis. The input variables in this study included: density of bone, implants and intermediate length, length of the cantlever, arrangement and number of implants, the degree of curvature of the jaw and turns the metal structure. A tension of 100 N was applied in the vertical direction. The authors concluded that the stress distribution showed improved in a bone with prosthetic intermediate and long implants free end [12]. The effects of variations in the length of the free ends were investigated by evaluating clinical cases, with distribution of load applied vertically to the implants. Were investigated obtaining models of clinical cases, introducing the arc geometry, location of implants and the maximum length allowed for calculation of the cantlever. The results showed that when the occlusal load was applied to the cantlever region of the first implant, the most distal (closest to the load), has compressive tensions and other implants, suffer tensile stress. Excessive stresses always occur when the occlusal load is applied to the distal regions of the cantlever. When we analyzed the distribution of the implants in the front area view and observe a distance of 11.1mm is possible to establish sufficient to provide esthetic, phonetic and biomechanical function without major complications with distal extension. The maximum length from the tip calculated by the model varied linearly with this distance of the implants, but always the compressive stresses are concentrated at the implant more distal region [13]. Tensions of masticatory forces acting on dental implants can generate compressive tensions, which are undesirable in the adjacent bone structures, may cause bone defects and eventual failure of the implant. The influence of the length and diameter of the implant in stress distribution was evaluated using the 3D FEM. Models simulating implants placed in vertical positions in the region of mandibular molars, with variations in the diameter and length of these were made. The masticatory load was simulated, perpendicular to the occlusal plane. The values of stresses were computed in ossoimplante interface. The areas of maximum stresses were localized around the neck area of the implants. The authors concluded that an increase in the diameter of the implant has a more satisfactory result that increasing the length of it in relation to the reduction of maximum tensions [14]. With the aid of computed tomography and (Cad/Cam - surgical template) computer program, clinical outcomes were analyzed in immediate loading guided surgery, implants as having four pillars that support a complete denture supportedby implants were installed in 23 patients with clinical follow-up 6-21 months. Bone insertion, suppuration, patient discomfort, infection and mobility were evaluated. The results showed that the success rate was 92.7% in the