Influence of abutment materials on the implant-abutment joint stability in internal conical connection type implant systems

PURPOSE: This study evaluated the influence of abutment materials on the stability of the implant-abutment joint in internal conical connection type implant systems. MATERIALS AND METHODS: Internal conical connection type implants, cement-retained abutments, and tungsten carbide-coated abutment screws were used. The abutments were fabricated with commercially pure grade 3 titanium (group T3), commercially pure grade 4 titanium (group T4), or Ti-6Al-4V (group TA) (n=5, each). In order to assess the amount of settlement after abutment fixation, a 30-Ncm tightening torque was applied, then the change in length before and after tightening the abutment screw was measured, and the preload exerted was recorded. The compressive bending strength was measured under the ISO14801 conditions. In order to determine whether there were significant changes in settlement, preload, and compressive bending strength before and after abutment fixation depending on abutment materials, one-way ANOVA and Tukey's HSD post-hoc test was performed. RESULTS: Group TA exhibited the smallest mean change in the combined length of the implant and abutment before and after fixation, and no difference was observed between groups T3 and T4 (P>.05). Group TA exhibited the highest preload and compressive bending strength values, followed by T4, then T3 (P<.001). CONCLUSION: The abutment material can influence the stability of the interface in internal conical connection type implant systems. The strength of the abutment material was inversely correlated with settlement, and positively correlated with compressive bending strength. Preload was inversely proportional to the frictional coefficient of the abutment material.

Comparison of metal wire reinforcement and glass fiber reinforcement in repaired maxillary complete denture / 대한치과보철학회지

PURPOSE: This study compared fracture strength and fracture modes between metal wire reinforcement and glass fiber reinforcement in repaired maxillary complete denture. MATERIALS AND METHODS: In this study, fracture was reproduced on center of maxillary complete dentures and the denture was repaired with auto-polymerizing resin. The experimental groups (n = 10) were subjected to the following condition: without reinforcing material (control group), reinforcing with metal wire (W group), reinforcing with glass fiber pre-impregnated with light-curing resin (SES MESH, INNO Dental Co., Yeoncheon, Korea, G group). The fracture strength and fracture modes of a maxillary complete denture were tested using Instron test machine (Instron Co., Canton, MA, USA) at a 5.0 mm/min crosshead speed. The flexure load was applied to center of denture with a 20 mm diameter ball attachment. When fracture occurred, the fracture mode was classified based on fracture lines. The Kruskal-wallis test and the Mann-whitney U test were performed to identify statistical differences at alpha=.05. RESULTS: W group showed the highest value of fracture strength, there was no significant difference (P>.05) between control group and G group. Control group and W group showed anteroposterior fracture mainly, group W showed adhesive fracture of denture base and reinforcing material. CONCLUSION: In limitation of this study, the glass fiber did not improve the fracture strength of repaired maxillary complete denture, and adhesive failure was occurred along the lines of glass fiber.

Effect of immobilization of the recombinant human bone morphogenetic protein 2 (rhBMP-2) on anodized implants coated with heparin for improving alveolar ridge augmentation in beagle dogs: Radiographic observations / 대한치과보철학회지

PURPOSE: The aim of this study was to evaluate the effect of immobilization of the recombinant human bone morphogenetic protein 2 (rhBMP-2) on anodized titaum implants coated with heparin to enhance the vertical alveolar ridge augmentation in the supraalveolar peri-implant defect region. MATERIALS AND METHODS: 18 pure titanium implants (7.0 mm in length, 3.5 mm in diameter) were manufactured for this study. All implants were anodized and designed insertion reference line marked with laser at the apical 2.5 mm from the fixture platform. Implantation of 6 noncoated anodized implants (Control group), 6 anodized implants physically adsorbed with rhBMP-2 by dip and dry method (BMP group) and 6 anodized implants chemically immobilized 3,4-dihydroxyphenylalanine (DOPA)-heparin/rhBMP-2 (Hep-BMP group) was performed in the both mandibular of three male adult beagle dogs using split-mouth design. Radiologic examinations were performed immediately after implant placement and 4 and 8 weeks after implant placement. The amount of mesio-distal bone augmentation was evaluated by measuring the vertical distance from the platform to the marginal bone. Statistical analysis was performed using one-way analysis of variance (SPSS version 18.0) and multiple comparison analysis of The Kruskal-Wallis test and the Mann-Whitney U test. Statistical significance was established at the 5%significant level. RESULTS: At the 4 weeks vertical alveolar ridge augmentation of Control group, BMP group and Hep-BMP group is 0.09 +/- 0.22 mm, 1.02 +/- 0.72 mm, and 1.29 +/- 0.51 mm, At the 8 weeks 0.11 +/- 1.26 mm, 1.11 +/- 0.58 mm, 1.59 +/- 0.79 mm according to radiographic observations. The two experimental groups showed a significantly increasing in vertical bone height compared with the control group (P.05). CONCLUSION: The rhBMP-2 coated implants were enhanced the vertical bone growth in the supraalveolar peri-implant defect area. However, there is no significant difference between chemically and physically coating method.

Effect of location of glass fiber pre-impregnated with light-curing resin on the fracture strength and fracture modes of a maxillary complete denture / 대한치과보철학회지

PURPOSE: This study evaluated the effect of glass fiber pre-impregnated with light-curing resin on the fracture strength and fracture modes of a maxillary complete denture. MATERIALS AND METHODS: Maxillary acrylic resin complete dentures reinforced with glass fiber pre-impregnated with light-curing resin (SES MESH, INNO Dental Co., Yeoncheon-gun, Korea) and without reinforcement were tested. The reinforcing material was embedded in the denture base resin and placed different regions (Control, without reinforcement; Group A, center of anterior ridge; Group B, rugae area; Group C, center of palate; Group D, full coverage of denture base). The fracture strength and fracture modes of a maxillary complete denture were tested using Instron test machine (Instron Co., Canton, MA, USA) at a 5.0 mm/min crosshead speed. The flexure load was applied to center of denture with a 20 mm diameter ball attachment. When fracture occurred, the fracture mode was classified based on fracture lines. The data were analyzed with one-way ANOVA at the significance level of 0.05. RESULTS: There were non-significant differences (P>.05) in the fracture strength among test groups. Group A showed anteroposterior fracture and posterior fracture mainly, group B, C and control group showed partial fracture on center area mostly. Most specimen of group D showed posterior fracture. CONCLUSION: The location and presence of the fiber reinforcement did not affect the fracture strength of maxillary complete denture. However, reinforcing acrylic resin denture with glass fiber has a tendency to suppress the crack.

Study of heat transfer to the implant-bone interface induced by grinding of occlusal surface of implant gold prosthesis / 대한치과보철학회지

PURPOSE: The purpose of this study was to analyze temperature change along the implant-bone interface induced by grinding the occlusal surface of implant gold prosthesis and to compare the temperature generated by grinding of prosthesis with different cooling methods. MATERIALS AND METHODS: The experimental gold prostheses were fabricated with dental gold alloy and castable abutment. The prostheses had 3 cylindrical protrusions on the occlusal surface with 1mm in height. Temperature was measured using 16 thermocouple wires attached to the implant fixture surface and the fixture was embedded in an acrylic resin block inside the 37degrees C water bath. Cylinders were grinded for a period of 30 second with a low-speed handpiece with green stone point. One cylindrical protrusion was grinded without cooling, the second one was grinded with air blow, and the third one was grinded with water-spray. RESULTS: The mean maximum temperature was measured more than 47degrees C of the implant and the maximum temperature was measured at the cervical portion of the implant in the group without cooling. There was statistically significant difference between the group without cooling and the groups with cooling (P.05). CONCLUSION: The results of this study support that the grinding of implant gold prosthesis without cooling may damage the peri-implant tissue. The continuous use of air blow and water-spray adjacent to prosthesis during the grinding of implant gold prosthesis may prove to be beneficial for cooling of the implant.

Pleomorphic Xanthoastrocytoma: Report of 3 Cases

Pleomorphic xanthoastrocytoma(PXA) is a rare neoplasm with favorable prognosis despite of its aggressive histological features. The authors report three cases of pleomorphic xanthoastrocytomas. The masses were in the temporal or parietal lobe of children or adolscence and presented as complex partial seizures. Total removal of mass was performed in all three cases and the seizure was abscent postoperatively. It is important to differentiate of pleomorphic xanthoastrocytoma from other malignant brain tumors and identify this type of glioma as a distinct entity.