Hua xi kou qiang yi xue za zhi = Huaxi kouqiang yixue zazhi = West China journal of stomatology最新文献

Objectives: This work aimed to evaluate the effect of artificial aging on the translucency and color difference (ΔE) of ultra-translucent zirconia and provide a reference for clinical application.

Methods: The discs of ultra-translucent zirconia from six brands (Wieland, 3M ESPE, Amann Girrbach, Kuraray Noritake, Upcera, and Besmile) were cut and sintered according to each manufacturer's product instructions; the experimental groups were named ZNT, LVP, AG, KAT, UPC, and BSM, respectively. IPS e.max Press was used as the control group (PLT). The specimens (n=6) were prepared with a diameter of 14 mm and a thickness of 1 mm. The specimens were subjected to artificial aging treatment according to the following conditions: in an autoclave at 134 ℃ at 0.2 MPa for 4, 8, and 12 h. According to the CIE1976Lab system, the CIE L*, a*, and b* values of the specimens before and after aging were measured by a co-lorimeter. The translucency parameter (TP) and ΔE were calculated.

Results: The mean TP values of each group before aging inorder were PLT>KAT>AG>ZNT>BSM>UPC>LVP. We found no significant difference in translucency in all experimental groups after aging for 4 and 8 h compared with those before aging. After 12 h of aging, the TP values of the KAT and ZNT groups were not significantly different from those before aging, but the TP values of the AG, BSM, LVP, and UPC groups were significantly lower than those before aging (P<0.05). The TP value of the control group was significantly higher than that of the other experimental groups at different stages (P<0.05). ΔE=3.3 was considered the visible color difference, and ΔE was less than 3.3 in all groups after 4 h of aging. After aging for 8 h, ΔE of the UPC group was slightly higher than 3.3. ΔE of the BSM and UPC groups was greater than 3.3 after 12 h of aging.

Conclusions: The TP and ΔE of different brands of ultra-translucent zirconia may change after various aging times. The translucency of some zirconia showed a decreasing trend and the color difference showed an increasing trend with the aging time.

Objectives: This test aimed to investigate the factors affecting the locking force between the implant and abutment and the amount of abutment subsidence in pure Morse taper connection implant systems.

Methods: With reference to the Bicon implant abutment connection design, different types of implant specimens and their corresponding types of abutments were fabricated. The implant-abutment locking taper was uniformly 1.5°. The locking depths were 1.0, 2.0, and 3.0 mm. The diameters of the locking column were 2.5, 3.0, and 3.5 mm. The thicknesses of the outer wall of the implant were 0.15 and 0.30 mm. The loading forces of the testing machine were 200, 300, and 400 N. At least 10 specimens of each group of implant-abutment were used. All specimens were loaded in the same manner using a universal testing machine (finger pressure + specified loading force, five times). The total height of the implant-abutment was measured before finger pressure, after finger pressure, and after the testing machine was loaded for five times to calculate the amount of sinking of the abutment. Finally, the implant and abutment were pulled apart using the universal testing machine, and the subluxation force was observed and recorded.

Results: The test loading force, locking depth, and locking post diameter had an effect on the implant-abutment locking force and abutment subsidence. The implant-abutment locking force increased with the increase in the test loading force, locking depth, and locking post diameter (R=0.963, 0.607, and 0.372, respectively), with the test loading force having the most significant effect. Abutment subsidence increased with the increase in test loading force (R=0.645) and decreased with the increase in locking depth and locking post diameter (R=-0.807 and -0.280, respectively), with locking depth having the most significant effect on abutment subsidence. No significant correlation was found between the thickness of the outer wall of the implant and the change in the magnitude of the implant-abutment locking force. However, an increase in the thickness of the outer wall of the implant decreased the amount of abutment subsidence, which was inversely correlated.

Conclusions: The locking force of the implant-abutment can be increased by adjusting the design of the pure Morse taper connection implant⁃abutment connection, increasing the locking depth and locking post diameter, and increasing the amount and number of times the abutment is loaded during seating. Problems, such as loosening or detachment of the abutment, can be reduced. The recommended abutment to be loaded should be no less than five times during seating to prevent the abutment from sinking and causing changes in the occlusal relationship in the later stages. Preliminary occlusal adjustments should only be conducted in the early stages of the use of temporary restorations, and

Objectives: This study aims to compare the accuracy of self-developed universal implant guide (SDG), 3D printed digital guide (DG), and free hand (FH) simulated implantation in the posterior tooth area of dental models.

Methods: Ten junior dentists were selected to place three implants in the 35, 37, and 46 tooth sites of the mandibular models (35, 36, 37, and 46 missing teeth) by using SDG, DG, and FH, and the process was repeated again to take the average value. Cone beam computed tomography (CBCT) was used to evaluate the global coronal deviation, global apical deviation, depth deviation, and angular deviation between the actual position and preoperative planned position.

Results: The coronal deviation and apical deviation of the three implant sites in the SDG group were not significantly different from those in the two other groups (P>0.05). The depth deviation and angular deviation in the SDG group were smaller than those in the DG group (P<0.05) and FH group (P<0.05), respectively. All deviations at site 37 in the SDG group were not different from those at site 35 (P>0.05), while the depth and angular deviation at site 37 in the DG group were higher than those at site 35 (P<0.05).

Conclusions: The precision of the self-developed universal dental implant guide can meet the requirements of clinical posterior implantation.

Objectives: This retrospective study explored the incidence of independent distal-lingual root (DLR) in mandibular first molars and the morphologic features of distal furcations through cone beam computed tomography (CBCT) in Beijing population.

Methods: A total of 401 CBCT images of both mandibular first molars existed were included. The sex of the patients, the incidence of DLR, the distal root trunk length (DRT), the locations of distal furcation entrance (DFE), and the separation angle of distal furcation (ADF) were recorded.

Results: The incidence rates of DLR were 33.2% on the subject level and 26.8% on the tooth level. The incidence of DLR was not different between genders but was higher on the right sides. The DRT values were 4.15 mm±1.02 mm. The ADF was 65.56°±11.56°. The DFE was located lingually, and 97.2% DFE was located more apically than buccal/lingual furcations.

Conclusions: A high incidence of DLR was found in the Beijing population. The DRT was longer than buccal and lingual sites. The DFE was located lingually with a wide separation. Understanding the morphological features of distal furcation can help clinicians to make proper treatment plans.

Objectives: This work aimed to study the correlation between FOXN3-SIN3A complex expression and non-syndromic oral clefts (NSOC) in Xinjiang.

Methods: In this study, 60 patients with NSOC attending the People's Hospital of Xinjiang Uygur Autonomous Region were recruited into the case group, including 30 cleft lip with or without cleft palate (NSCL/P), 30 cleft palate only (CPO), and 30 healthy children in the control group. The expression levels of FOXN3, SIN3A, and NEAT1 in peripheral blood of each group were detected by high-throughput second-generation sequencing technology and quantitative reverse transcription polymerase chain reaction (RT-qPCR). Receiver operating characteristic (ROC) curve and area under the curve (AUC) were used to analyze the diagnostic efficiency of NSOC.

Results: The comparison of the NSOC and control groups showed that FOXN3, SIN3A, and NEAT1 genes increased compared with the control group. The differences were all statistically significant (P<0.05). The AUCs of FOXN3, SIN3A, and NEAT1 in the NSCL/P group were 0.933 [95%CI=(0.864, 1.000)], 0.822 [(95%CI=(0.713, 0.932)], and 1.000[95%CI= (1.000, 1.000)], respectively. The AUCs of FOX-N3, SIN3A, and NEAT1 in the CPO group were 0.891 [95%CI=(0.806, 0.976)], 0.688 [95%CI=(0.552, 0.824)], and 1.000 [95%CI=(1.000, 1.000)], respectively.

Conclusions: The results showed a correlation between the rising gene expression of FOXN3, SIN3A, and NEAT1 in peripheral blood and the occurrence of NSOC in Xinjiang. This work provides a theoretical basis for further study of the FOXN3-SIN3A complex as biomarkers to facilitate the early screening, disease prediction, and early prevention of NSOC.