Maximum Insertion Torque Values Research Articles

In-vitro evaluation of the effects of insertion and sterilization procedures on the mechanical and surface characteristics of mini screws

The aim of the present study was to investigate the effects of insertion and sterilization on primary stability and to examine the mechanical and surface characteristics of mini screws. 140 miniscrews (70 Dual-Top; 70 Ortho-Easy) were divided into 3 groups. Group 1: control group, 10 miniscrews of each brand, evaluated without any primary procedure. Group 2: 30 miniscrews of each brand, each inserted into the sawbone once, then sterilized and tested. Group 3: 30 miniscrews of each brand, each inserted into the sawbone twice, sterilized after each insertion and then tested. The miniscrews were evaluated for changes in primary stability, mechanical and surface characteristics with scanning electron microscopy (SEM) analysis, torsion tests, maximum insertion-removal torques and vertical-horizontal pull out strength tests. The maximum insertion torque values of the unused miniscrews (Group 1) were found to be significantly higher than those of the reused (Groups 2, 3) mini screws (p<0.05). Removal torque, vertical-horizontal pull-out strength and torsional strength value changes were found to be statistically insignificant. In SEM analysis, wear and atrophy were seen on the threads of used miniscrews especially in the apical region and the oxide layer was seen to have disappeared from some regions of the coated miniscrews. Although wear and atrophy were detected in SEM analysis of used miniscrews, the overall primary stability and fracture torque resistance tests did not show any significant changes after the first and second insertion and sterilization procedures.

In vitro assessment of maximum insertion and removal torque with three different miniscrews on artificial maxilla and mandible

ObjectiveThe aim of this study was to measure and correlate the values of maximum insertion and removal torques of miniscrews in artificial posterior maxilla and posterior mandible. This study also aimed at assessing the effect of bone density and screw design on these values. MethodsThree groups of self-drilling miniscrews obtained from three different manufacturing companies, having same diameters (1.4 mm) and lengths (8 mm) were used. All screws were inserted in artificial bone samples (Sawbones) and the maximum insertion and removal torque values were recorded with digital torque sensor. ResultsThere were significant differences, statistically, between maximum insertion and removal torque values of different groups of miniscrews. Insertion torque values in the posterior mandible were significantly higher than those in the posterior maxilla and the maximum insertion and removal torques were directly proportional to each other. ConclusionIt is suggested to perform a pre-insertion drilling due to the higher insertion torque in the posterior mandible, to maintain an acceptable range of maximum insertion torque and achieve primary stability without unnecessary bone damage. It is concluded that the screw design as well as bone characteristics have significant effects on the stability of the screw.

The influence of miniscrew insertion torque.

The aim of this in vitro study was to evaluate the progressive development of surface microdamage produced following the insertion of orthodontic miniscrews (OMs) into 1.5 mm thick porcine tibia bone using maximum insertion torque values of 12 Ncm, 18 Ncm, and 24 Ncm. Aarhus OMs (diameter 1.5 mm; length 6 mm) were inserted into 1.5 mm porcine bone using a torque limiting hand screwdriver set at 12 Ncm, 18 Ncm, and 24 Ncm. A custom rig equipped with a compression load cell was used to record the compression force exerted during manual insertion. A sequential staining technique was used to identify microdamage viewed under laser confocal microscopy. Virtual slices were created and stitched together to form a compressed two-dimensional composition of the microdamage. Histomorphometric parameters, including total damage area, diffuse damage area, maximum crack length, maximum damage radius, and maximum diffuse damage radius, were measured. Kruskal-Wallis Tests and Wilcoxon Rank-Sum Tests were used to analyse the generated data. All OMs inserted using 12 Ncm failed to insert completely, while partial insertion was observed for two OMs inserted at 18 Ncm. Complete insertion was achieved for all OMs inserted at 24 Ncm. Histomorphometrically, OMs inserted using 24 Ncm produced a significantly larger diffuse damage area (P < 0.05; P < 0.05) and maximum diffuse damage radius (P < 0.05; P < 0.05), for both the entry and exit surfaces, respectively, compared with the 12 Ncm and 18 Ncm groups. Insertion torque can influence the degree of OM insertion and, subsequently, the amount of microdamage formed following insertion into 1.5 mm thick porcine tibia bone. An increase in insertion torque corresponds with greater insertion depth and larger amounts of microdamage.

The Effects of Implant Design, Bone Quality, and Insertion Process on Primary Stability of Dental Implants: An In-vitro Study

The aim of this study was to analyse the maximum insertion torque (MIT) with respect to the implant thread face angle, bone quality and the insertion process. Two implants were designed and made: one with high face angle (HFA) and the other with low face angle (LFA). Bovine bones were classified, and then the MIT values of the implants were measured per round using standard protocol. Finally, three-way ANOVA was used to interpret the MIT values. For the main effects, MIT values (mean and standard error) of LFA (17.4 ± 0.7 N cm) and HFA implants (20.8 ± 0.7 N cm) were significantly different. The MIT values for the D4 (9.4 ± 0.6 N cm), D3 (19.1 ± 0.7 N cm), and D2 (28.8 ± 1.1 N cm) bones were significantly different. Considering the higher primary stability as an essential provision for immediate load implants, it is recommended to use implants featured with higher thread face angles.

Effect of vertical placement angle on the insertion torque of mini-implants in human alveolar bone.

ABSTRACTObjective: The aim of the present ex-vivo study was to evaluate the effect of the vertical placement angle of mini-implants on primary stability by analyzing maximum insertion torque (MIT). Methods: Mini-implants were placed in 30 human cadavers, inserted at either a 90° or 60° angle to the buccal surface of the maxillary first molar. Out of 60 self-drilling mini-implants used, half were of the cylindrical type and half were of the conical type. Primary stability was assessed by means of measuring the MIT. Data were subjected to analysis of variance (ANOVA) and Newman-Keuls tests. A significance level of 5% was adopted. Results: The MIT was higher for both mini-implant types when they were placed at a 90° angle (17.27 and 14.40 Ncm) compared with those placed at a 60° angle (14.13 and 11.40 Ncm). Conclusions: MIT values were differed according to the vertical mini-implant placement angle in the maxillary posterior area. Regardless of the type of mini-implant used, placement at a 90° angle resulted in a higher MIT.

Integrative Performance Analysis of a Novel Bone Level Tapered Implant.

Primary mechanical stability, as measured by maximum insertion torque and resonance frequency analysis, is generally considered to be positively associated with successful secondary stability and implant success. Primary implant stability can be affected by several factors, including the quality and quantity of available bone, the implant design, and the surgical procedure. The use of a tapered implant design, for instance, has been shown to result in good primary stability even in clinical scenarios where primary stability is otherwise difficult to achieve with traditional cylindrical implants-for example, in soft bone and for immediate placement in extraction sockets. In this study, bone-type specific drill procedures are presented for a novel Straumann bone level tapered implant that ensure maximum insertion torque values are kept within the range of 15 to 80 Ncm. The drill procedures are tested in vitro using polyurethane foam blocks of variable density, ex vivo on explanted porcine ribs (bone type 3), and finally in vivo on porcine mandibles (bone type 1). In each test site, adapted drill procedures are found to achieve a good primary stability. These results are further translated into a finite element analysis model capable of predicting primary stability of tapered implants. In conclusion, we have assessed the biomechanical behavior of a novel taper-walled implant in combination with a bone-type specific drill procedure in both synthetic and natural bone of various types, and we have developed an in silico model for predicting primary stability upon implantation.

EFFECT OF ANGLED INSTALLATION OF ORTHODONTIC MINI-IMPLANTS ON PRIMARY STABILITY

AIM: The aim of this work was evaluate the insertion and removal torque for orthodontic mini-implants inserted in different inclination. MATERIALS AND METHODS: Ten self-drilling mini-implants from the brand SIN (Sistema de Implantes Nacional, São Paulo/SP, Brazil), and the surgical kit for their insertion were used. Two plaques of synthetic bone of 120 mm x 170 mm x 41,5 mm were used (Sawbones, Pacific Research Laboratories Inc, Vashon, Wash), with 1,5 mm height, simulating the cortical bone (density 40 pcf) and 40 mm simulating the medullary bone (density 15 pcf). In each block, five areas were demarcated for each mark, totalizing ten areas. The ten mini-implants were inserted by the same operator, previously calibrated; five of them at 900 and five at 600, using the manual key kit. After the insertion of all the mini-implants, the final threading and the reading of insertion torque value were carried out with a manual torque wrench digital Lutron TQ-8800 (Lutron Electronic Enterprise Co., Ltd, Taipei, Taiwan) until the trans-mucosal profile achieve the cortical bone. The maximum insertion torque value was registered in N/cm. After all the implants inserted, the measurement of removal torque was started, performed in the same way of insertion, but in the opposite anticlockwise. The results were submitted to the T test (parametric) and to a Mann-Whitney test (non-parametric). RESULTS: The results demonstrated that the insertion torque was lower than the removal one in both insertion degrees, with statistically significance. Despite insertion torque at 90 degrees had been lightly higher than that inserted at 60 degrees, they were not statistically significant. CONCLUSION: In view of the results, it was possible conclude that insertion at 60º angulation does not offer advantages to the primary stability for orthodontic mini-implants.

Biologic evaluation of a hollow-type miniscrew implant: An experimental study in beagles

The aims of this study were to assess the biologic stability of a newly designed hollow (H-type) miniscrew compared with conventional (C-type) miniscrews through histomorphometric and histologic analysis. Both types of miniscrews were placed into the maxillae and the mandibles of 12 beagles. Maximum insertion torque, Periotest (Siemens AG, Bensheim, Germany) value, bone-implant contact, and bone volume were measured. The overall success rates of the H-type were 78.3% in the maxilla and 60.0% in the mandible. Mean maximum insertion torque values of the H-type were 14.2 N-cm in the maxilla and 20.9 N-cm in the mandible. The Periotest values of the H-type were -1.5 in the maxilla and -6.4 in the mandible. Mean maximum insertion torque and Periotest values of the H-type were higher than those of the C-type. In the maxilla, the bone-implant contact values of the H-type were 37.3% and 32.3% at 3 and 12 weeks, respectively. In the mandible, the bone-implant contact values were 31.4% and 18.5% at 3 and 12 weeks, respectively. Considering the lower success rate and the insufficient bone-implant contact and bone volume of the H-type in the mandible, the clinician should choose a suitable combination of miniscrews depending on local bone quality and implantation site, such as an H-type in the maxilla and a C-type in the mandible.

Is there a difference between the primary stability of anodized and non-anodized mini-screws subjected to repeated cycles of autoclave sterilization?

Objective: To determine if autoclave sterilization has any deleterious effects on the clinical stability of anodized versus non-anodized mini-screws. Materials and Methods: Thirty anodized and thirty non-anodized Aarhus System mini-screws (American Orthodontics, Sheboygan, WI) were utilized. Each group was divided into three test groups. In each group, mini-screws that were sterilized once using a steam autoclave (Statim 5000, SciCan USA, Canonsburg, Pa) served as the control group (n=10). The other two test groups involved mini-screws that were subjected to a repeated cycles of sterilization for five (n=10) and ten (n=10) times. All sixty mini-screws were inserted at a 90 ° angle into custom-designed synthetic blocks that simulated the average mandible of a healthy adult. The maximum insertion torque and the lateral displacement at 0.025, 0.05, 0.1, 0.25, 0.5, and 1 mm were recorded for each sample and subjected to statistical testing. A two-way ANOVA, and a three-way mixed ANOVA were used for statistical analyses. Results: Maximum insertion torque values displayed significant differences between the anodized and non-anodized groups (p<0.001) as well as the sterilization cycles (p<0.001). No significant group and cycle interaction was observed. No significant differences were found between the groups and sterilization cycles in the evaluation of the lateral displacement test. However, there was a significant group/cycle/displacement interaction (p<0.001). Conclusion: Surface treatment of mini-screws with anodization produced differences when compared to standard surface mini-screws following autoclave sterilization. The differences between the two types of mini-screws did not indicate a potential stability concern.

A correlation between bone (B), insertion torque (IT), and implant stability (S): BITS score

Although criteria for assessing bone quality have been reported, an overall score that correlates bone quality with the primary stability and secondary stability of implants is not yet available. The purpose of this article was to propose a scoring index that will establish a correlation among the bone density values from computed tomography, maximum insertion torque values, and resonance frequency analysis in different phases of implant treatment. In this study, 60 implant sites were evaluated to assess bone density (Hounsfield units), insertion torque values (Ncm), and primary stability and secondary stability (implant stability quotient values obtained by using resonance frequency analysis). On the basis of computed tomography data, the bone was classified as D1 to D4. The insertion torque was noted and classified into 2 groups, A and B. The implant stability quotient values obtained from resonance frequency analysis depicting primary stability and secondary stability were classified into 5 groups. The primary score noted was a result of the values obtained for the 3 parameters at the time of implant placement. The secondary score was obtained by considering the values of the bone density and resonance frequency analysis recorded at different time intervals. Bone densities of D2, D3, and D4 were noted, dividing the bone type into 3 groups. The maximum torque noted in the study was 40 Ncm. The difference between various insertion torque values and bone types was found to be statistically nonsignificant. Higher mean implant stability quotient values were obtained for primary and secondary stability for the D2 bone than for D3 and D4 bone. When analyzed according to the time of insertion, the mean values increased at second stage surgery in all bone types. The difference in mean values among all bone types was found to be statistically significant (P<.001). A comparison of primary and secondary implant stability quotient values in all bone types did not find any statistical significance (P=.780). A score was recorded at the time of implant placement and at the time of second stage surgery, and the prosthetic treatment was planned accordingly. The score highlights the importance of considering the association of bone quality, insertion torque values, and stability as denoted by implant stability quotient throughout treatment. Based on the variation in the score noted at recall visits, alterations in the treatment plan can be made with respect to the healing period and prosthetic design.

Geometrical design characteristics of orthodontic mini-implants predicting maximum insertion torque.

ObjectiveTo determine the unique contribution of geometrical design characteristics of orthodontic mini-implants on maximum insertion torque while controlling for the influence of cortical bone thickness.MethodsTotal number of 100 cylindrical orthodontic mini-implants was used. Geometrical design characteristics of ten specimens of ten types of cylindrical self-drilling orthodontic mini-implants (Ortho Easy®, Aarhus, and Dual Top™) with diameters ranging from 1.4 to 2.0 mm and lengths of 6 and 8 mm were measured. Maximum insertion torque was recorded during manual insertion of mini-implants into bone samples. Cortical bone thickness was measured. Retrieved data were analyzed in a multiple regression model.ResultsSignificant predictors for higher maximum insertion torque included larger outer diameter of implant, higher lead angle of thread, and thicker cortical bone, and their unique contribution to maximum insertion torque was 12.3%, 10.7%, and 24.7%, respectively.ConclusionsThe maximum insertion torque values are best controlled by choosing an implant diameter and lead angle according to the assessed thickness of cortical bone.

Effects of a newly designed apparatus on orthodontic skeletal anchorage.

Objective:An appliance was designed to increase the cortical bone surface contact area of miniscrew implants (MSIs). The purpose of this in vitro study was to evaluate the effects of this appliance on the anchorage force resistance and the stability of orthodontic MSIs.Materials and Methods:A total of 48 MSIs were placed into bone specimens prepared from the ilium of bovines. Half were placed with the newly designed apparatus and half were placed conventionally. All the specimens were subjected to tangential force loading perpendicular to the MSI with lateral displacement of 0.6 mm, using an Instron Universal Testing machine. The maximum removal torque of each tested specimen was also recorded. Both study and control groups were divided into two subgroups based on whether they had thin and thick cortical bone.Results:The test group had statistically higher force anchorage resistance and maximum insertion torque values than the control group (P < 0.001). The results were found to be more significant in cases in which the cortical bone was thin (P < 0.001).Conclusions:Within the limits of this in vitro study, the present findings suggest that the newly designed apparatus might have a favorable effect on MSI stability in patients presenting with thin cortical bone. Clinical studies are necessary to confirm the results that were observed in vitro.

Insertion torque and orthodontic mini-implants: A systematic review of the artificial bone literature

This article systematically reviewed the literature to (1) identify variables that were associated with maximum insertion torque values during the insertion of orthodontic mini-implants into artificial bone, (2) quantify such associations and (3) assess adverse effects of this procedure. Computerized and manual searches were conducted up to 24 February 2012. Selection criteria included studies that (1) recorded maximum insertion torque during the insertion of orthodontic mini-implants into artificial bone, (2) used sample sizes of five screws or more, (3) assessed maximum insertion torque with electronic torque sensors, and (4) used orthodontic mini-implants with a diameter smaller than 2.5 mm. ASTM Standards F543-07(ε1) and F1839-08(ε1) and the Cochrane Handbook for Systematic Reviews were used as guidelines for this systematic review. Quality assessments were rated according to the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. A total of 23 studies were selected, many of which were multiple publications of the same study. Many domains in the risk of bias assessments were scored as "high" or "unclear" risk of bias. A wide variety of implant, test block, and insertion procedure-related associations with maximum insertion torque were recorded. The quality of most outcomes was classified as "moderate." Outcomes could not be combined in a meta-analysis because of high risk of bias, poor standardization, high heterogeneity, or inconsistency in direction of outcomes within or between studies. Adverse effects were only assessed in one study. Future studies should control publication bias, consult existing standards for conducting torque tests, and focus on transparent reporting.

The Influence of Cortical Width of Sheep Bone on the Primary Stability of Dental Implants: An In Vitro Study

To explore the relationship between primary implant stability and cortical bone thickness. Twenty-three implants were inserted into fresh sheep bone. The cortical width of implant recipient sites was determined using cone-beam computed tomography (CBCT). The maximum insertion torque value of each implant was recorded. Implant stability was measured using an Osstell system. Spearman's correlation coefficient was used to evaluate the correlations among variables. The cortical width and Hounsfield unit mean values were 3.3 ± 1.0 (mm) and 1468.5 ± 272.3, respectively. The correlation between cortical bone thickness and Osstell value was not statistically significant (p > 0.01). The cortical bone thickness evaluated using CBCT had no correlation with the primary stability of dental implants.

Effects of insertion angle and implant thread type on the fracture properties of orthodontic mini-implants during insertion

To determine the effects of insertion angle (IA) and thread type on the fracture properties of orthodontic mini-implants (OMIs) during insertion. A total of 100 OMIs (self-drilling cylindrical; 11 mm in length) were allocated into 10 groups according to thread type (dual or single) and IA (0°, 8°, 13°, 18°, and 23°) (n = 10 per group). The OMIs were placed into artificial materials simulating human tissues: two-layer bone blocks (Sawbones), root (polymethylmethacrylate stick), and periodontal ligament (Imprint-II Garant light-body). Maximum insertion torque (MIT), total insertion energy (TIE), and peak time (PT) were measured and analyzed statistically. There were significant differences in MIT, TIE, and PT among the different IAs and threads (all P < .001). When IA increased, MIT increased in both thread groups. However, TIE and PT did not show significant differences among 0°, 8°, and 13° IAs in the dual-thread group or 8°, 13°, and 18° IAs in the single-thread group. The dual-thread groups showed higher MIT at all IAs, higher TIE at 0° and 23° IAs, and longer PT at a 23° IA than the single-thread groups. In the 0°, 8°, and 13° IA groups, none of the OMIs fractured or became deformed. However, in the 18° IA group, all the OMIs were fractured or deformed. Dual-thread OMIs showed more fracturing than deformation compared to single-thread OMIs (P < .01). In the 23° IA group, all OMIs penetrated the artificial root without fracturing and deformation. When OMIs contact artificial root at a critical contact angle, the deformation or fracture of OMIs can occur at lower MIT values than those of penetration.

Insertion torque and success of orthodontic mini-implants: A systematic review

In this systematic review, we analyzed whether recommended maximum insertion torque values of 5 to 10 Ncm were associated with higher success rates of orthodontic mini-implants compared with mini-implants inserted with maximum insertion torque values beyond this range. Objective assessments of stability, variables that influence maximum insertion torque values, and adverse effect of interventions were also assessed in the studies selected for our PICO (patient problem or population, intervention, comparison, and outcomes) question. Computerized and manual searches of the literature were conducted up to February 24, 2012, for human studies that assessed these objectives. Our eligibility criteria selected studies that (1) used sample sizes of 10 or more, (2) recorded maximum insertion torque during the insertion of orthodontic mini-implants, (3) inserted implants with a diameter smaller than 2.5 mm, and (4) applied orthodontic forces for a minimum duration of 4 months. Confounding was assessed through the analysis of risk of bias, and the validity of outcomes was rated according to the GRADE approach. The Cochrane Handbook for Systematic Reviews of Interventions was our main guideline for the methodology. Seven nonrandomized studies met the eligibility criteria. All associations between specific maximum insertion torque values and success were based on literature rated as having low quality. The reasons for these judgments included subjective definitions of success, poor-quality torque sensors, and high risks for selection, performance, detection, and reporting biases. A risk of multiple publication bias was also suspected. All associations between maximum insertion torque and factors related to implant, patient, location, and surgery were rejected; few studies reported on adverse effects. Currently, no evidence indicates that specific maximum insertion torque levels are associated with higher success rates for orthodontic mini-implants. Additional research on this topic is therefore necessary. The following guidelines for future studies are suggested: (1) systematically review the animal and laboratory literature, (2) perform maximum insertion torque tests on artificial bone, (3) test associations in animal studies before conducting clinical trials, (4) test associations between maximum insertion torque and the stability of orthodontic mini-implants with objective quantitative recordings rather than subjective qualitative measures, (5) measure maximum insertion torque with digital sensors rather than with mechanical devices, (6) assess the stability of orthodontic mini-implants at preestablished times, (7) consult our risk-of-bias analysis, and (8) analyze the adverse effects of interventions.

Heat generation during implant placement in low‐density bone: effect of surgical technique, insertion torque and implant macro design

The study aimed to investigate the effect of surgical technique, implant macrodesign and insertion torque on bone temperature changes during implant placement. In the in vitro study, 144 self-tapping (blueSKY(®) 4×10mm; Bredent) and 144 non-self-tapping (Standard implant(®) 4.1×10mm; Straumann) were placed in osteotomies prepared in pig ribs by lateral bone condensing or bone drilling techniques. The maximum insertion torque values of 30, 35 and 40Ncm were used. Real-time bone temperature measurement during implant placement was performed by three thermocouples positioned vertically, in tripod configuration around every osteotomy, at a distance of 5mm from it and at depths of 1, 5 and 10mm. Data were analysed using Kruskal-Wallis, Mann-Whitney U-tests and Regression analysis. Significant predictor of bone temperature at the osteotomy depth of 1mm was insertion torque (P=0.003) and at the depth of 10-mm implant macrodesign (P=0.029), while no significant predictor at depth of 5mm was identified (P>0.05). Higher insertion torque values as well as non-self-tapping implant macrodesign were related to higher temperatures. Implant placement in sites prepared by bone drilling induced significantly higher temperature increase (P=0.021) compared with bone condensing sites at the depth of 5mm, while no significant difference was recorded at other depths. Compared with 30Ncm, insertion torque values of 35 and 40Ncm produced significantly higher temperature increase (P=0.005; P=0.003, respectively) at the depth of 1mm. There was no significant difference in temperature change induced by 35 and 40Ncm, neither by implant macrodesign at all investigated depths (P>0.05). Placement of self-tapping implants with low insertion torque into sites prepared by lateral bone condensing technique might be advantageous in terms of thermal effect on bone.

Angled-predrilling depth and mini-implant shape effects on the mechanical properties of self-drilling orthodontic mini-implants during the angled insertion procedure

To investigate the effects of orthodontic mini-implant (OMI) shape and angled-predrilling depth on the mechanical properties of OMIs during the angled insertion procedure. A total of 30 OMIs (self-drilling type, 7 mm in length) were allocated into six groups according to the OMI shape (cylindrical or tapered) and angled-predrilling depth (control, 1.5-mm and 4.0-mm angled-predrilling; predrilled with 1-mm-diameter drill-bit), as follows: C-con, C-1.5, C-4.0, T-con, T-1.5, and T-4.0 groups (N = 5 per group). The OMIs were installed at an angle of 60° in double-layer artificial bone blocks that simulated the cortical and cancellous bone (Sawbone(®)). Total insertion time (TIT), maximum insertion torque (MIT), total insertion energy (TIE), and inclination of the time-torque graph (INC) were measured. Within the same shape group, angled-predrilling had a shorter TIT than did the control (control vs 1.5; control vs 4.0; all P < .05). MIT and TIE decreased in the order of control, 1.5-mm, and 4.0-mm angled-predrilling (control vs 1.5; 1.5 vs 4.0; all P < .05), but INC increased from control to 1.5-mm angled-predrilling and decreased from 1.5-mm to 4.0-mm angled-predrilling within the same shape group (control vs 1.5, 1.5 vs 4.0; all P < .05). The MIT of the tapered group was greater than that of the cylindrical group (C-con vs T-con, C-1.5 vs T-1.5; all P < .05, C-4.0 vs T-4.0; P < .01). In the same angled-predrilling depth, no differences were observed in TIE between the cylindrical and tapered groups (C-1.5 vs T-1.5, C-4.0 vs T-4.0; all P > .05). In angled-predrilling insertion of OMIs into thick cortical bone, tapered OMIs might be a better choice than cylindrical OMIs for increasing primary stability because of higher MIT and similar TIE values.

Thread shape factor: evaluation of three different orthodontic miniscrews stability

The thread shape factor (TSF) to evaluate the relationships between geometrical characteristics and mechanical properties of the temporary anchorage devices (TADs) has recently been introduced. This in vitro experimental study evaluated in 30 different tests with three TADs: ORTHOImplant (1.8 mm diameter and 10 mm length; 3M Unitek), Tomas (1.6 mm diameter and 10 mm length; Dentaurum), and Orthoeasy (1.7 mm diameter and 10 mm length; Forestadent). Scanning electron microscopy images were acquired for each TAD to measure the TSF; afterwards, the maximum insertion torque (MIT) was evaluated and thereafter pull-out tests on two differently designed organic bone analogs were carried out using a testing machine with a crosshead speed of 2 mm/minute being applied. One-way analysis of variance with group as factor was performed. Post hoc multiple comparisons Bonferroni test was used. Rank-transformed data were used when asymmetry of data was shown. To assess correlation between characteristics, load, and MIT, Spearman's rank correlation coefficient was used. A P-value of 0.05 was considered statistically significant. Significant direct correlations were found between TSF and depth and both load and MIT. Particularly, a correlation of 0.90 (P < 0.001) was found between depth and MIT for 2.2 mm cortical thickness. The authors conclude that MIT and maximum load values of pull-out test are statistically related to depth of the thread of the screw and to TSF.

Undersized Implant Site Preparation to Enhance Primary Implant Stability in Poor Bone Density: A Prospective Clinical Study

Achieving primary implant stability in areas with poor bone density is often challenging to the clinician. Previous research has suggested that modified surgical protocols might be beneficial in such situations. The objective of the present clinical study was to evaluate the survival rate of implants placed using undersized implant site preparation in areas with poor bone density. A total of 52 implants were placed in 29 patients. Of the 52 implants, 26 were surgically placed according to the standard drilling protocol (control group) and 26 were placed in low-density bone using an adapted bone drilling method (test group). The maximum insertion torque values and resonance frequency analysis measurements were also recorded. All implants were examined clinically and radiographically at follow-up visits during the study period. Oral hygiene status, bleeding on probing, peri-implant probing depth, and implant survival rate were assessed. According to the survival criteria used in the present study, no failure was recorded, and the overall survival rate was 100% for both groups after 12 months. The mean probing depth was 2.75 ± 0.75 mm in the test group and 2.87 ± 0.79 mm in the control group. The mean insertion torque value was 35.19 ± 4.79 Ncm in the test group and 34.62 ± 5.82 Ncm in the control group. The resonance frequency analysis value was 68.58 ± 4.81 implant stability quotient and 66.69 ± 5.41 implant stability quotient in the test and control groups, respectively. The observed differences were not statistically significant (P > .05). The results of the present study suggest that placement of implants by an adapted drilling technique in sites with poor bone density is beneficial in enhancing primary implant stability and improving the implant survival rate.