PURPOSE: The purpose of this study is to compare the removal torque between prefabricated and customized implant abutment screw. MATERIALS AND METHODS: Three types of implant system (Osstem, Astra, Zimmer) were used. For each system, prefabricated abutment screw (control group) and customized abutment screw (test group) were used to connect the fixture and the abutment (n = 6). Digital torque gauze was used to control the tightening torque and the screws were tightened under each manufacturer's recommendation. 10 minutes after the connection the same tightening torque was applied, and 5 minutes after the second connection, the removal torque was measured. This procedure was repeated 10 times. In the cyclic loading test, 10 minutes after the first connection to the 6 groups (n = 3), the same tightening torque was applied, and a total of 1,000,000 time loading was applied at 30 degree angle to long axis with 50 N load. Repeated measures of ANOVA test (alpha=.05) was used as statistics to evaluate the effect of repeated loading number on the removal torque. Independent t-test was used to evaluate the difference in removal torque after cyclic loading. RESULTS: The removal torque significantly decreased as the number of loading repetition increased (P<.05). In the 10 time repetition test, there was no significant difference between the prefabricated and customized implant abutment screw of the 3 implant system (P<.05). Also in the cyclic loading test, there was no significant difference between the prefabricated and customized implant abutment screw of the 3 implant system (P<.05). CONCLUSION: Within the limitation of this study, there was no significant difference in the removal torque between the prefabricated abutment screw and customized abutment screws.
Axis, Cervical Vertebra ; Dental Implants ; Torque

PURPOSE: The aim of this study was to evaluate the improvement of osteogenic potential of biphasic calcium phosphate (BCP) bone substitute coated with synthetic cell-binding peptide sequences in a standardized rabbit sinus model. METHODS: Standardized 6-mm diameter defects were created bilaterally on the maxillary sinus of ten male New Zealand white rabbits, receiving BCP bone substitute coated with synthetic cell binding peptide sequences on one side (experimental group) and BCP bone substitute without coating (control group) on the other side. Histologic and histomorphometric analysis of bone formation was carried out after a healing period of 4 or 8 weeks. RESULTS: Histological analysis revealed signs of new bone formation in both experimental groups (4- and 8-week healing groups) with a statistically significant increase in bone formation in the 4-week healing group compared to the control group. However, no statistically significant difference in bone formation was found between the 8-week healing group and the control group. CONCLUSIONS: This study found that BCP bone substitute coated with synthetic cell-binding peptide sequences enhanced osteoinductive potential in a standardized rabbit sinus model and its effectiveness was greater in the 4-week healing group than in the 8-week healing group.
Artificial Cells ; Bone Regeneration ; Bone Substitutes ; Calcium ; Durapatite ; Humans ; Hydroxyapatites ; Male ; Maxillary Sinus ; Oligopeptides ; Osteogenesis ; Rabbits

PURPOSE: The aim of this study was to determine whether biphasic calcium phosphate (BCP) bone substitute with two different concentrations of Escherichia coli-expressed recombinant human bone morphogenetic protein 2 (ErhBMP-2) enhances new bone formation in a standardized rabbit sinus model and to evaluate the concentration-dependent effect of ErhBMP-2. METHODS: Standardized, 6-mm diameter defects were made bilaterally on the maxillary sinus of 20 male New Zealand white rabbits. Following removal of the circular bony windows and reflection of the sinus membrane, BCP bone substitute without coating (control group) was applied into one defect and BCP bone substitute coated with ErhBMP-2 (experimental group) was applied into the other defect for each rabbit. The experimental group was divided into 2 subgroups according to the concentration of ErhBMP-2 (0.05 and 0.5 mg/mL). The animals were allowed to heal for either 4 or 8 weeks and sections of the augmented sinus and surrounding bone were analyzed by microcomputed tomography and histologically. RESULTS: Histologic analysis revealed signs of new bone formation in both the control and experimental groups with a statistically significant increase in bone formation in experimental group 1 (0.05 mg/mL ErhBMP-2 coating) after a 4-week healing period. However, no statistically significant difference was found between experimental group 1 and experimental group 2 (0.5 mg/mL ErhBMP-2 coating) in osteoinductive potential (P<0.05). CONCLUSIONS: ErhBMP-2 administered using a BCP matrix significantly enhanced osteoinductive potential in a standardized rabbit sinus model. A concentration-dependent response was not found in the present study.
Animals ; Bone Morphogenetic Protein 2 ; Bone Morphogenetic Proteins ; Bone Regeneration ; Bone Substitutes ; Calcium ; Durapatite ; Escherichia coli ; Humans ; Hydroxyapatites ; Male ; Maxillary Sinus ; Membranes ; Osteogenesis ; Rabbits ; X-Ray Microtomography

PURPOSE: Among available biomaterials, bioceramics have drawn special interest due to their bioactivity and the possibility of tailoring their composition. The degradation rate and formulation of bioceramics can be altered to mimic the compositions of the mineral phase of bone. The aim of this study was to investigate the bone formation effect of amorphous calcium phosphate glass cement (CPGC) synthesized by a melting and quenching process. METHODS: In five male beagle dogs, 4 x 4 mm 1-wall intrabony defects were created bilaterally at the mesial or distal aspect of the mandibular second and fourth premolars. Each of the four defects was divided according to graft materials: CPGC with collagen membrane (CM), biphasic calcium phosphate (BCP) with CM, CM alone, or a surgical flap operation only. The dogs were sacrificed 8 weeks post-surgery, and block sections of the defects were collected for histologic and histometric analysis. RESULTS: There were significant differences in bone formation and cementum regeneration between the experimental and control groups. In particular, the CPGC and BCP groups showed greater bone formation than the CM and control groups. CONCLUSIONS: In conclusion, CPGC was replaced rapidly with an abundant volume of new bone; CPGC also contributed slightly to regeneration of the periodontal apparatus.
Animals ; Bicuspid ; Biocompatible Materials ; Bone Substitutes ; Calcium ; Calcium Phosphates ; Collagen ; Dental Cementum ; Dogs ; Freezing ; Glass ; Humans ; Hydrazines ; Hydroxyapatites ; Male ; Membranes ; Osteogenesis ; Regeneration ; Surgical Flaps ; Transplants

Background/Aims: Ledipasvir/sofosbuvir (LDV/SOF) shows high efficacy and safety in patients with genotype 1-hepatitis C virus (HCV). We aimed to investigate the efficacy and safety of LDV/SOF in real-world Mongolian patients. Methods: Between 2015 to 2019, 23 (0.5%) and 5,005 patients (99.5%) with genotype 1a and 1b HCV, respectively, were treated with a fixed-dose tablet containing 90 mg ledipasvir and 400 mg sofosbuvir for 12 weeks, and 81 patients (1.6%) with previous experience of interferon (IFN)-based treatment received additional 1,000 mg ribavirin. HCV RNA was measured at 4, 12, and 24 weeks after the first dose to determine rapid virologic response, end of treatment response (ETR), and sustained virologic response at 12 weeks after end of treatment (SVR12). Results: Most patients (n=5,008; 99.6%) achieved ETR and SVR12 without virologic relapse. Patients with genotype 1a showed low rates of ETR and SVR12 in only 16 patients (69.6%). There was no significant difference in SVR12 rate between patients regardless of IFN experience (n=81; 1.6%), cirrhosis (n=1,151; 22.9%), HCV RNA >6×106 IU/mL (n=866; 17.2%), or liver stiffness >9.6 kPa (n=1,721; 34.2%) (100.0%, 99.3%, 99.4%, and 99.4%, respectively). No severe adverse events (AEs) were reported, and there was no dose reduction or interruption due to AE. The most common AEs were headache (n=472; 9.4%), fatigue (n=306; 6.2%), abdominal discomfort (n=295; 5.9%), and skin rash (n=141; 2.8%). Conclusions LDV/SOF showed high efficacy and safety for patients with genotype 1, especially 1b HCV, in Mongolia. The real-world data might be applicable to patients in other Asian-Pacific countries.