Perda óssea marginal em implantes distais em próteses fixas implantossuportadas : desenvolvimento metodológico para estudo prospectivo radiográfico

Abstract

Previous biomechanical studies show a great stress concentration at the distal region of implants adjacent to the cantilever in fixed implant-supported complete dentures (FISCD). Thus, it is necessary to evaluate the marginal bone levels in this region by means of intraoral radiographs. The objectives of this study were: 1) to develop a specific methodological approach for the radiographic evaluation of marginal bone loss (MBL) around the most distal implants adjacent to prosthetic cantilever in FISCD, 2) to investigate possible correlation between MBL, cantilever extension and mesio-distal inclination of the distal implants. Seven patients with 10 FICSD (n=20 implants) were accompanied during one year at the clinics of Faculty of Dentistry of PUCRS. Measurements of the cantilever extension of the metallic infrastructures were carried out during the prosthetic rehabilitation. The mesio-distal inclinations of the implants relative to the occlusal plane were defined through the cone beam computer tomography (CBCT). Intra-oral digital radiographs were obtained by customized positioning devices following delivery of the prostheses (baseline) and one year after the delivery. Cantilever extension, inclination and MBL of the distal implants were analyzed descriptively and inferentially: the correlation between MBL, cantilever extension and inclination of the implants were evaluated by Spearman‟s correlation coefficient with significance level of 5%. The mean values and their variability were; cantilever extension 9,80± 3,69 mm, distal inclination 2,50 (1,00; 10,50) degrees, mesial inclination -3,00(-5,00; -1,00) degrees, mesial MBL -0,08 (-0,28; 0,05) mm and distal MBL -0,04(-0,35; 0,09) mm. No statistical correlation was detected neither between MBL and cantilever extension nor between MBL and inclination of the distal implants. The proposed radiographic and methodological technique used in this study was reliable and reproducible. The findings of MBL after 1 year of follow-up were in accordance with the literature.