[Research on the influence of different implant site on the implant-bone-interface stress distribution in zygomatic implant denture].

OBJECTIVE: To probe the implant-bone-interface stress distribution of zygomatic implant denture concerning different implant sites. METHODS: Three-dimensional finite element model for severe atrophy maxillary posterior-tooth area was established biomechanically in this study by computer technique and zygomatic implant was simulated into the model in the first-maxillary-premolar region, the second-maxillary-premolar region, the first-maxillary-molar region and the second-maxillary-molar region respectively. Vertical loading, buccal (30 degrees) loading and lingual (30 degrees) loading were preformed, 100 N. Then these load cases were calculated and analyzed. RESULTS: 1) When the implant site was placed in the first-maxillary-premolar region, the buccal side of zygomatic implant exposed out of the bone and didn't meet the clinical request. 2) As far as the tensile stress peak value in the maxillary posterior-tooth area was concerned, the highest value was recorded when the implant was placed in the second-maxillary-molar region, and then the medium value was recorded when the implant was placed in the second-maxillary-premolar region, and the smallest was recorded when the implant in the first-maxillary-molar region. As far as the compressive stress peak value in the maxillary posterior-tooth area was concerned, the highest value was recorded when the implant was placed in the second-maxillary-molar region, and then the medium was recorded when the implant was in the first-maxillary-molar region, and the smallest value was presented when the implant was in the second-maxillary-premolar region. As far as the tensile and compressive stress peak values in the zygomatic area were concerned, the highest value was recorded when the implant was in the second-maxillary-premolar region, and then the medium value when the implant was in the first-maxillary-molar region, and the smallest when the implant was in the second-maxillary-molar region. CONCLUSION: The first-maxillary-molar region is the best implant site of zygomatic implant denture.

[A retrospective study of infection after onlay graft].

OBJECTIVE: To investigate the treatment and prevention of infection after alveolar crest onlay bone graft. METHODS: From January 2006 to May 2010, 11 infection cases after onlay graft on alveolar crest were reviewed to evaluate the infection time, clinical situation, treatment measure, and therapeutic effect. RESULTS: The infection of all 11 cases occurred about 15 days after bone graft, which showed either soft tissue fistulae or bone graft exposure in the oral cavity. Three cases failed because of persistent infection. The infection of the other 8 cases was controlled after a series of comprehensive therapy, and most of the bone graft was reserved and implant restoration finally completed. CONCLUSIONS: After the effective and comprehensive therapy, infected bone graft can be reserved. But to ensure the survival rate of bone graft, the most important thing is to prevent infection in perioperative period.

[Effects of alveolar bone resorption on stress of tooth/implant-supported restoration connected by precision attachment].

OBJECTIVE: To investigate the effects of alveolar bone resorption on stress of tooth/implant-supported restoration connected by precision attachment using three-dimensional finite element(FEM) approach. METHODS: The FEM was applied to analyze the stress distribution of tooth/implant-supported restoration connected by precision attachment under various loading conditions when the alveolar bone was absorbed to different level. RESULTS: The stress values of the tooth, implant and their surrounding bone increased when their surrounding bone decreased by bone absorption. CONCLUSION: The stress values of the tooth, implant and their surrounding bone were closely related with the bone resorption.