RESUMO
The maxillary sinus grafting procedure has proven to be an acceptable modality for bone augmentation to provide a base for endosseous implants, routinely used for the rehabilitation of posterior maxilla. Perforation of the membrane is the most common complication in this type of procedure. This paper presents a technique for repairing a perforated Schneiderian membrane with a conjunctive connective tissue graft harvested from the palate and shows the histological and radiographic evaluation of the results. Ten consecutives cases with the occurrence of membrane perforation were included in this study. All were repaired with a flap of tissue removed from the palatine portion near to the surgical site. The technique is demonstrated through a clinical case. The results showed successful integration of 88.8% of the implants after 12 months from prosthesis installation. Histological evaluation of the samples showed that the use of nanocrystalized hydroxyapatite showed an adequate stimulation of boné neoformation within 6 months. Radiographic evaluation revealed a small apical implant bone loss, not compromising their anchorages and proservation. Thus, it can be concluded that the use of conjunctive technique with collected palate flap for sealing the perforation of the membrane of the sinus may have predictable result.
RESUMO
AIM: Occlusal loading has to be considered a key factor influencing bone resorption due to the stress transmitted to surrounding tissues by the implant-abutment structure. The aim of this study was to evaluate, through a photo-elastic investigation, the patterns of tensions distribution of two different implant shapes, which were cylindrical and conical. METHODS: A 100N load was applied to two implant-abutment structures (with and without a metal-ceramic crown) incorporated in photo-elastic resin. Modification in light refraction were recorded and analyzed through a computerized software. Measurements of stripe extension and position were evaluated. RESULTS: Stress distribution around tapered implant was evaluated to be more uniform than in cylindrical one which demonstrated a high stress concentration at the more cervical region and in the apical region. The presence of a metal-ceramic crown caused an increase in tensions at the implant-resin interface. CONCLUSION: Conical implants distributed stresses to a larger and well-defined volume of resin and this can cause a decrease of forces acting at the interface. This could be due to the "wedge effect" of this fixture shape which could be considered superior in terms of stress distribution than cylindrical one.