Background and Aim: Maintaining the primary TORQUE of the abutment screw is a common problem related to implant-supported restorations; a failure in this respect often leads to screw loosening. The abutment screw plays a critical role in the longterm stability of restorations. This study aimed to assess the effect of two abutment connection types with and without cyclic loading on REMOVAL TORQUE value (RTV). Materials and Methods: A total of 24 abutments and fixtures were evaluated in this in-vitro experimental study. Two abutments with internal and external connections were tightened to fixtures using a digital TORQUE-meter according to the manufacturer’ s instructions. Half of the samples were subjected to cyclic loading with a 100-N mechanical load at a 1-Hz frequency (500, 000 cycles) applied at 23± 1° C with 50± 5% humidity. Next, the RTV was measured for each abutment. Two-way analysis of variance (ANOVA) was used to assess the effect of the abutment system and cyclic loading on RTV. Results: The highest RTV belonged to the internal connection abutment without cyclic loading (22 Newton-centimeter (Ncm)), while the lowest RTV was noted with the external connection abutment subjected to cyclic loading (14 Ncm; P<0. 01). There was no statistically significant interaction effect between the two variables (the abutment system and cyclic loading; P=0. 839). The RTV in the internal hexagon abutments was significantly higher than that in the external hexagon abutment system (P<0. 001). Cyclic loading significantly reduced the RTVs in both abutments (P<0. 001). Conclusion: According to the results, internal connection abutments experience less screw loosening.

Background and Aim: Facial growth pattern is one of the important factors in orthodontic treatment planning. The aim of this study was to compare the inclination of the posterior teeth in subjects with a normal and vertical growth pattern.Materials & Methods: Fifty 16 to 20 year old individuals having no history of orthodontic treatment, dental extraction, spacing and crowding in posterior teeth were selected for this case - control study. These individuals were divided into two groups of vertical and normal growth patterns based on SN-MP and jarabak Index. Study casts provided for these patients were trimmed from anterior to the second premolar and from posterior to the first molar.Lateral surfaces of casts were trimmed perpendicular to the occlusal surface tangential to the most prominent cusps of these 4 or at least 3 (two molars and one premolar) teeth. The angle between lateral surface of the cast and the occlusal surface of each tooth was considered as axial inclination. The results were statistically analyzed using Mann Whitney U and t tests.Results: The mean age of the studied group was 18.3±1.6 The mean axial inclination of maxillary first permanent molar with normal growth pattern was 27.5±16.8 (right side) and 26.2±14.7 (left side). The amount of this variable with vertical growth pattern was 23.4±11.9 (right side) and 24.8±14.7 (left side). The mean axial inclination of mandibular first permanent molar with normal growth pattern was 27.24±15.2 (right side) and 27.44±14.8 (left side) and with vertical growth pattern was 23.8±13.9 (right side) and 23.5±14.3 (left side).Conclusion: Buccolingual inclination of the teeth has no effect on orthodontic treatment planning.

Introduction: Usually osseointegration takes between three to six months after implant placement but patients are interested to have early loading. There are no definitive criteria for measuring bone mineral density (BMD), insertion TORQUE (IT) (final TORQUE force) and resonance frequency analysis (RFA) (primary implant stability) to determine exact loading time based on the relationship between the above-mentioned parameters. The aim of this study was to determine the relationship between IT, RFA and BMD in screw-type implants.Materials and Methods: This clinical trial was conducted on 18 patients who were candidates for ITI implant placement. Written consent was taken and jaw bone density was determined via a digital radiography technique before surgery. After implant placement, RFA and IT were measured. Fifty-five ITI implants of the total 62 implants placed were evaluated; the implants were 12 mm long with a diameter of 4.1 mm. Data was analyzed with Pearson’s test using SPSS.15 software (a=0.05).Results: There was a significant relationship between IT, RFA and BMD. Pearson’s test showed a correlation coefficient of 0.872 to 0.789 between the three parameters, indicating a strong relationship between them. The mean bone density was 1.468±0.042 g/cm2; the mean RFA was 66.01±2.2 ISQ and the mean IT was 34.62±3.33 N/cm2.Conclusion: Based on the results of the present study there is a significant relationship between, IT, RFA and BMD (p value=0.001).

Introduction: Some clinicians use a handheld screw driver instead of a TORQUE wrench to definitively tighten abutment screws. The aim of this study was to compare the REMOVAL TORQUE of one-piece and two-piece abutments tightened with a handheld driver and a TORQUE control ratchet.Methods: 40 ITI implants were placed in acrylic blocks and divided into 4 groups. In groups one and two, 10 ITI one-piece abutments (Solidâ) and in groups three and four, 10 ITI two-piece abutments (Synoctaâ) were placed on the implants. In groups one and three abutments were tightened by 5 experienced males and 5 experienced females using a handheld driver. In groups two and four abutments were tightened using a TORQUE wrench with TORQUE values of 10, 20 and 35 N.cm. Insertion TORQUE and REMOVAL TORQUE values of the abutments were measured with a digital TORQUE meter.Results: The insertion TORQUE values (ITVs) of males in both abutments were significantly higher than those of females. ITVs in both Solidâ and Synoctaâ abutments tightened with a handheld screwdriver were similar to the TORQUE of 20 N.cm in the TORQUE wrench. REMOVAL TORQUE values (RTVs) of solidâ abutments were higher than those of synoctaâ abutments.Conclusion: The one- piece abutments (solidâ) showed higher RTVs than the two-piece abutments (synoctaâ). Hand driver does not produce sufficient preload force for the final tightening of the abutment.

The angle of long axis of tooth crown is called tip in mesiodostal and TORQUE in faciolingual direction. Both have special importance for producing an ideal occlusion. The aim of the present study was determination of the average tip and TORQUE of each permanent tooth in well treated patients with edgewise system compare to control group with normal occlusion. In this study, 19 well treated cases through standard edgewise technique with non extraction strategy and 20 students of pre-university schools with normal occlusion according to IOTN were selected. Reference points and lines were marked on facial surface of each tooth on casts. Special device was designed for measuring the faciolingual and mesiodistal inclination of crowns. After 3 times measuring the tip and TORQUE of teeth, student t-test and Kruskal – Wallis analysis were used for statistical analysis.The mean age of control group was 18.8 ± 0.5 year and in treated group was 20.3 ± 0.8. There was significant difference between mean of TORQUE in control group and treated group for upper lateral incisor (4.75±5.21, 8.76±5.82 respectively, p<0.03). Also a significant difference was seen in average TORQUE of lower second premolar between control group and treated one (-23.48±5.99, -26.66±4.64 respectively, p<0.05). There were no significant differences in tip of teeth between two groups. In comparison with Andrews study, in normal occlusion group, upper canine & first molar and lower lateral & first premolar had more buccal root TORQUE. Except the TORQUE of upper lateral incisor and lower 2nd premolar, TORQUE and tip of other teeth had no significant difference.

TORQUE, speed, and power as mechanical variables are associated with the functional performance of any rotating machinery. The real-time performance and the efficiency of a machine can be determined with on-line measurement of these parameters. In this investigation a rotary TORQUE meter (transducer) was constructed from strain gauge sensors for measuring the TORQUE of rotating shafts. The system converts the TORQUE of rotating shaft into voltage signals, based on the principle of strain gauge resistance. The signals are then amplified and converted into digital signals. These digital signals are sent to a RF receiver circuit for displaying and storage. Results of static calibration and a series of dynamic tests confirmed a satisfactory operation of the designed apparatus in various conditions. Also, the TORQUE measuring range, resolution and the accuracy were from 3 to 700 N m, 3 N m and 1%, respectively.

In this paper, a stator-flux-reference frame control method is proposed in order to control the speed and TORQUE of an Interior Permanent Magnet Synchronous Machine (IPMSM) in different loads condition. Direct TORQUE Control method (DTC) based on Space Vector Modulation (SVM) is used for control of IPMSM. In the proposed control method, conventional PI controller is used for controlling the stator flux, and TORQUE of the motor. Also, a fuzzy controller is considered to improve the dynamic performance of DTC technique for speed control. In comparison to the conventional reference flux controller methods, this method, in addition, improves the TORQUE profile of the motor drive. Moreover, it reduces copper losses. Simulation results for a 240V, 120A, 2500rpm, IPMSM confirm the appropriate performances of the method.

Conventional energy sources like fossil fuels are no longer viable due to their limitations and environmental impact. The demand for cleaner, more efficient energy solutions has led to the development of electric machines with smaller volumes and higher output. The family of permanent magnet Vernier motors have high TORQUE output at very low speeds while being very small in volume. In conventional SVPM, the core losses are high, which leads to heating and reducing the efficiency of the motor, and the power factor of the motor is also low, and the TORQUE can increase in relation to the motor volume. The reluctance TORQUE theory, along with the normal output TORQUE of the motor, increases the final TORQUE of the motor. In addition, the toothing of the rotor reduces the cross-sectional area and weight of the rotor. With the reduction of the cross-sectional area, the eddy currents in the core are reduced, the power factor increases and the efficiency of the motor improves. Therefore, in this paper, a spoke-type permanent magnet Vernier motor with a rotor similar to the reluctance rotor has been designed, which has higher TORQUE, lower losses, and higher power factor compared to conventional spoke-type permanent magnet Vernier motors.