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).

Background: Titanium miniscrews are used at an ever‑ increasing rate to provide orthodontic anchorage. The aim of this study was to evaluate the mechanical performance of miniscrews after dry and steam sterilization. Materials and Methods: In this experimental study, a total of 72 miniscrews from two different manufacturers with a diameter of 1. 6 mm and height of 8 mm were divided into six groups (n = 12). One group of screws from each manufacturer was considered as the control group; the second underwent steam sterilization; and the last group was subjected to dry sterilization. Insertion and fracture Torques of each miniscrew were assessed by a Torque tester. Data were analyzed using the Kruskal– Wallis and Mann– Whitney tests (P < 0. 05). Results: For Jeil miniscrew, no statistically significant differences were detected between the steam‑ sterilized and control groups in their Insertion Torques (P > 0. 05). There was a statistically significant difference between the steam sterilized, dry sterilized and control groups with respect to their fracture Torque (P < 0. 001). For Hubit miniscrew, there were no significant differences between steam sterilized, dry sterilized and control groups in their Insertion Torque (P > 0. 05) and between steam sterilized and control groups with respect to their fracture Torque (P > 0. 05). There were significant differences in the mean values of Insertion and fracture Torques between the two different manufacturers (P < 0. 001). Conclusion: Steam sterilization had no detrimental effects on Torque values of miniscrews, but dry heat sterilization affected their mechanical properties.

Objective: The present study aimed to determine the Insertion Torque and fracture resistance of infra-zygomatic crest (IZC) screws as critical factors influencing primary stability. Methods: A total of 40 stainless steel IZC mini-screw implants (MSIs) were obtained from two different manufacturers (Bio-Ray, Taiwan, and S. K. Surgicals, India). Each group comprised 20 MSIs of identical dimensions (2 ×14 mm). To simulate a clinical scenario, a customized jig was utilized to embed these screws into human maxillary bone blocks for evaluation of maximum Insertion Torque (MIT), and into polyacrylic glass blocks for assessment of fracture resistance. A digital Torque gauge was used to obtain precise Torque measurements. Results: There were significant differences in MIT between the groups at the tip and neck areas of the screws (P<0. 05). The Bio-Ray IZC screws manifested significantly greater Insertion Torque at the tip and significantly lower Insertion Torque at the neck compared to the S. K. Surgicals group (P<0. 05). However, the two groups demonstrated no significant difference in terms of fracture resistance (P=0. 484). Conclusions: The evaluated mini-implants displayed a diverse range of Insertion Torques at various parts of the screws (increasing from tip to mid and neck regions). It is imperative to consider various Torque values during screw Insertion to mitigate the risk of tissue damage and screw breakage. The present findings revealed no significant difference in fracture resistance between the two brands of mini-implants, suggesting that the fracture Torque was primarily influenced by factors beyond the manufacturer of the MSIs.

Background. This study aimed to compare Insertion Torque (IT) and implant stability quotient (ISQ) values immediately and three months after surgery with standard drilling (SD) and osseodensification (OD) drilling methods. Methods. In this prospective study, 39 implants with the same diameter and length were placed in 21 patients using SD (23 implants) and OD (16 implants) methods in the posterior maxilla. The amounts of IT after surgery and ISQ after surgery and three months later were evaluated. The data were extracted and statistically analyzed with PASS2 software. The difference between IT and ISQ was determined by the two-way repeated-measures ANOVA at a significance level of 0. 001. Results. Immediately after surgery, the amount of IT using the OD drilling method was 37% higher than the SD drilling (P<0. 001). ISQ values after surgery did not show a significant difference between SD and OD (P1<0. 176). Three months after surgery, the ISQ values in both groups were not significantly different. ISQ values for all OD and SD group experimental parameters remained above the threshold value of 68. IT values showed a positive correlation with ISQ values at baseline. Conclusion. In the present study, the OD technique provided a higher IT rate after surgery compared to the SD method,however, no difference was seen between the two groups regarding ISQ value either after surgery or three months later.

Back pain is a common medical problem. There is no clear cause for the back pain problem so far, but in most cases, spinal instability can be noted. Lumbar spine fixation is performed to treat the problems of low back pain. Spinal fixation can be done with or without surgery. One of the surgical methods is the use of spinal screws in which the strength and stability of the screw are of great importance. The strength and stability of the screw in the bone reduces the time and cost of treatment, reduces the amount of bleeding and accelerates the patient's treatment. In this study, screws were inserted using a digital Torque meter. An impact was applied using an impact hammer and resonated sound was recorded using a microphone. The vibration mode of the screw was obtained by processing the signal generated by MATLAB R2017 software and plotting the fast Fourier transform. Finally, tensile test was performed to obtain the ultimate pull-out force. The innovation of this study was to use modal analysis method and to correlate its results with that of the ultimate pull-out force and peak Insertion Torque. In this study, five screws with different screw depth, and screw thread crest thickness were examined. Also, the effect of self-tapping was investigated. The peak Insertion Torque, ultimate pull-out strength and natural frequency occurred at 182 Nm, 992 N and 1916 Hz, respectively, for the cylindrical pedicle screw. By comparing the obtained data, results showed a linear relationship between Insertion Torque and pull-out force of the screws. Due to the lack of significant difference between natural frequency and pull-out force of the self-drilling and non-self-drilling tip screws (comparing between screws number 3 and 4 and between 1 and 5), the use of self-tapping screws can be advantageous. The trend of the dependent parameters in all three methods i. e. Insertion Torque, pull-out force and natural frequency are the same, indicating the non-destructive advantage of modal analysis in in-vivo surgical application.

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.

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.