ISSN:1056-6163    

出版商:OVID    

年代:2000

数据来源: OVID

ISSN:1056-6163    

出版商:OVID    

年代:2000

数据来源: OVID

ISSN:1056-6163    

出版商:OVID    

年代:2000

数据来源: OVID

ISSN:1056-6163    

出版商:OVID    

年代:2000

数据来源: OVID

ISSN:1056-6163    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

&NA;Occlusal overload may contribute to the extensive crestal bone loss often noted around late‐failure dental implants. A particularly high risk of traumatic overload occurs with the posterior single‐unit implant restoration because the restoration itself is usually wider than the implant, creating the potential for a cantilever effect with high bending moments. The objective of this study was to evaluate the simulated effects of axial and off‐axial vertical loads on stress gradients at the implant/bone interface of a single‐unit osseointegrated root‐form endosseous dental implant. A two‐dimensional finite element model was generated. A 490‐N load was applied at 0, 2, 4, and 6 mm from the vertical axis of the implant. Off‐axis loading resulted in greatly increased compressive stresses within the crestal cortical bone on the side to which the load was applied and similarly increased tensile stresses on the side opposite the load. These stresses increased considerably with each mm increase off axis of the applied load. These data suggest that offaxis loading of single‐unit implant restorations provides a significant contribution to increased stresses at the implant/cortical bone interface. The distance off axis at which the load is applied is also significant. (Implant Dent 2000;9:207‐218)

ISSN:1056-6163    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

&NA;The aim of the study was to evaluate the mechanical performance and the structure of neoformed bone around hydroxyapatite‐coated titanium fixtures according to guided bone regeneration techniques. Ten hydroxyapatitecoated titanium fixtures were inserted in the femurs of five rabbits, in which a cortical defect was created and after the insertion of the fixture, covered with a resorbable membrane obtained from bovine Achilles tendon collagen Type I (A implant). In the same femur, a second fixture was inserted in similar cavities without application of the membrane (B implant). After 60 days, the animals were sacrificed, and block sections of the femoral bone con taining the implants were embedded in polymethylmetacrylate and subjected to tensile shear‐stress at break testing. After the detachment of the implants from the bone, their surfaces were examined with a scanning electron microscope. Tensile shear‐stress values for A and B implant specimens were comparable to some extent, but the former had a lower performance. In this regard, scanning electron microscope observations showed that the neoformed cortical bone present cervically around implant A was much thicker than around implant B. (Implant Dent 2000;9:219‐225)

ISSN:1056-6163    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

&NA;Studies concerning natural and synthetic graft materials that have been used in different medical procedures have focused on freezedried bone, coral, hydroxylapatite, and tricalcium phosphate. This study histologically investigates the effects of these materials on the healing of bone defects. The experiments were performed on 30 albino rabbits. Cavities were drilled in the posterior right tibias of rabbits and were filled with coral, freeze‐dried bone, hydroxylapatite, or calcium hydroxide. One cavity was left unfilled as a control. The bone in which the materials were implanted was excised at 7, 15, 30, 45, and 60 days. After the histological staining procedures, the prepared materials were observed using a light microscope. Although all materials showed good bone remodeling at the end of 60 days, coral and hydroxylapatite materials could be seen in the bone structure. The most effective materials within bone defect improvement were freeze‐dried bone and calcium hydroxide. (Implant Dent 2000;9: 226‐235)

ISSN:1056-6163    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

&NA;The reuse of transgingival healing abutments has been advocated by several implant manufacturers, but cleaning and sterilization procedures to yield clean and optimal surfaces have yet to be developed. The objective of thisin vitroproject was to investigate various cleaning and sterilization regimens for the removal of biological debris to support reattachment of subgingival connective tissue. Simulated clinical healing abutment surfaces were exposed to culture medium with serum for 1 hour to simulate biological exposure. Simulated healing abutment surfaces not contaminated by serum were used to represent the “as‐is” healing abutment surface without priorin vivouse. The discs were cleaned with detergent before sterilization by ultraviolet light (UV) or steam autoclaving (AC) both with and without 1‐ and 5‐minute plasma cleaning (PC). A series of surface analytical techniques (XPS, AES, and surface contact angles) andin vitroanalysis of cell attachment and spreading using gingival fibroblasts were performed. After exposure to the simulated biological conditions, clinical cleaning followed by UV resulted in contaminated surfaces and relatively high levels of cell attachment. PC before UV treatment enhanced surface energetics but did not affect cell attachment and spreading. AC increased surface wetting angles; which were decreased somewhat by previous PC. Cell attachment was significantly reduced by AC. Although some increase in cell attachment after longer plasma cleaning was noted in the AC group, no difference in cell spreading was seen in any AC group. Cell spreading seemed to be less for all AC groups compared with all UV, as‐is, and control groups. Although certain cleaning (PC) and sterilization (UV) procedures can be effective for cleaning transgingival healing abutments, those using AC are questionable due to their propensity for organic and inorganic contamination and unfavorable surface alteration. (Implant Dent 2000;9:236‐246)

ISSN:1056-6163    

出版商:OVID    

年代:2000

数据来源: OVID

摘要:

&NA;Between 1994 and 1999, 50 patients were treated with either profound parodontopathy (30) or periimplantitis (20). Half of each of the two groups of patients was treated conventionally, and the other half was treated with laser support. Before the operation, microbiological examinations were carried out, in addition to registering the clinical findings and taking x‐rays. These procedures were repeated after the operation, and again after 6, 12, 24, 36, 48, and 60 months. The surgical part of therapy for each half of the patient groups included surface decontamination with diode laser light (1‐watt output, maximum of 20 seconds) in addition to conventional procedures. The values of the laser‐supported therapy were lower than those specified in the relevant literature. The relapse rate of the two diseases (13% for the periimplantitis and 23% for the parodontopathy group) after 5 years was lower than the comparative values of researched literature where decontamination was not included in the therapy. We think that integrating diode laser light decontamination in the approved treatment schemes for periimplantitis and parodontitis contributes considerably to the success of this therapy. (Implant Dent 2000;9:247‐251)

ISSN:1056-6163    

出版商:OVID    

年代:2000

数据来源: OVID