Zirconia ceramic combined with CAD/CAM fabrication procedures allow the production of large and complex restorations as a superstructure for tooth abutments, bridge frameworks and dental implants. A new generation of zirconia ceramic with better mechanical properties is emerging and is indicated for use in implant abutment. To establish the clinical application of this new zirconia ceramic (C-Pro NANOZR:ceria-stabilized tetragonal zirconia polycrystal alumina nanocomposite), we examined the flexural strength of C-Pro NANOZR for three kinds of round-shaped specimens in different burning methods.
Full-, middle- and pre-sintered C-Pro NANOZR were used in this study. Specimens were assigned to four groups of cross-sectional shape(R=0, R=0.5, R=1.0 and R=1.7). The three-point bending test of specimens was performed according to ISO 6872 in a universal testing machine at the cross head speed of 1 mm/min and with a support span length of 30 mm. After fracture, the obtained values were subjected to statistical analysis (ANOVA and Fisher's PLSD test, p＜0.05). After the three-point bending test, the fractured surface of the specimen was observed by a scanning electron microscope (SEM) at 150× magnification to determine the mode of failure.
The following means in MPa were found for the different groups of full-, middle- and pre-sintered C-Pro NANOZR:R=0(906.0, 740.0, 997.4), R=0.5(918.2, 883.1, 1,101.3), R=1.0 (995.0, 988.5, 1,174.1), R=1.7 (1,212.6, 1,011.4, 1,275.9). The flexural strength was significantly different between the full-, middle- and pre-sintered C-Pro NANOZR in R=0, R=0.5, R=1.0 and R=1.7. Large corner radius exhibited significantly higher flexural strength values than small corner radius in the round-shaped blocks. Pre-sintered blocks showed the highest flexural strength values. From SEM images of the fractured surface of C-Pro NANOZR, the middle- and pre-sintered CPro NANOZR exhibited sharp fracture of the corner, however, the full-sintered C-Pro NANOZR indicated blunt fracture. The full-sintered C-Pro NANOZR showed crack-blunting from the edge of the radius.
Based on the methodology employed, it was concluded that the corner radius of the round-shaped blocks and the difference in burning method had a significant influence on flexural strength values.
In this study, the use of Er:YAG irradiation to firmly adhere carbonate apatite calcined at 500℃ (CA) particles, which were thought to remain, to the surface of the implant was evaluated in vitro. A CA slurry was applied to the surface of pure Ti and CaTiO3-coated Ti substrates before Er:YAG irradiation. The degree of CAparticle adhesion to the Er:YAG lased substrates was evaluated by EPMA, IR and SEM after three-way syringe washing and ultrasonic treatment. The substrates were immersed for two days and seven days in a bodysimulating fluid, and the form of the crystals deposited on their surfaces was observed by SEM, elemental and state analyses of Ca and P atoms were conducted using EPMA, and the samples were examined for deposition of a bone-similar apatite phase. They were also examined to determine whether CA could be made to adhere under irradiation conditions in which the temperature remained below 53℃, a threshold value at which a bony irreversible change occurs. The results of SEM, EPMA, and IR examination after Er:YAG laser irradiation showed that CA adhered to the titanium substrates. SEM and EPMA observations revealed that a bone-similar apatite phase was deposited during immersion in the body-simulating fluid. Under appropriate irradiation conditions, in which the temperature due to laser irradiation was lower than 53℃, CA particles were successfully attached to both pure Ti and CaTiO3-coated Ti substrates.
The present report describes abnormal bone hyperplasia at the alveolar crest between implants placed around the mandibular molar area in three patients who have been medicated with bisphosphonate for osteoporosis. All three patients were female, and were aged 66, 68 and 67 years old. They complained of difficulty of brushing beneath the superstructure of implants. Dental radiography showed a band-like radiopacity at the alveolar bone crest between the mandibular molar implants. They were diagnosed with bone hyperplasia in the mandible. The lesion was surgically resected under local anesthesia after removing the superstructure in 2 of 3 patients, and sclerosis and normal bone tissue were observed histologically. These findings highlight the need for clinicians to monitor patients receiving bisphosphonate therapy.
The first requirement of implant treatment is to obtain sufficient bone quantity in the implant placement area. We have developed a method to obtain new bone and bone apposition nonsurgically using minor tooth movement (MTM) before insertion of implants. Here, we report two cases treated using this approach that both had satisfactory outcomes.
Case 1 was a 46-year-old woman with insufficient vertical bone quantity in the area where the maxillary right first molar was lost. There was some distance between the root apex of the second premolar and maxillary sinus. In this case, the maxillary second premolar was distally moved to the area of tooth loss using MTM. The period of orthodontic treatment was 13 months. An implant was inserted in the original area in which the second premolar had been present. The superstructure was then placed on the implant. Four years have passed since this treatment and the outcome is satisfactory.
Case 2 was a 29-year-old man with insufficient vertical bone quantity in the area where the maxillary right first molar had existed. The root apex of the second premolar touched the maxillary sinus. The maxillary second premolar was distally moved using MTM. The period of orthodontic treatment was 10 months. An implant was inserted into the newly made space and the superstructure was placed on the implant. Metamorphosis was observed in the remodeled bone wall of the maxillary sinus attached to the distal part of the moved maxillary second premolar. After three years and two months, the outcome is favorable.
These two cases show that the MTM approach makes it possible to obtain new bone and bone apposition and to insert an implant in the newly made space in the original bone.