Peak Insertion Torque Research Articles

Fracture Resistance of Commonly Used Self-drilling Mini-implants of Various Diameters

Context: Self-drilling mini-implants are commonly used in orthodontic treatment procedures, but there is limited information regarding their fracture resistance in areas of high-density bone without predrilling. Aims: The objective of this study is to compare and evaluate the maximum insertion torque and fracture resistance of 3 commonly used self-drilling mini-implants in India, and to assess the influence of variation in diameter in torque generation. Materials and methods: 90 mini-implants from 3 different manufacturers with 2 different diameters were drilled into acrylic blocks using a dial indicating torque screwdriver. All mini-implants were drilled at the rate of 20-30 rotations/min, implants were drilled until they fractured. Torque generated at the point of fracture is shown on the dial of the screwdriver. Measurements of the peak insertion torque value for each manufacturer were recorded separately. Statistical analysis: Analysis of variance, post hoc Bonferroni test. Results: Analysis of variance test showed a significant difference among all the manufacturers in both the diameters with P < .05. Implants of 1.6 mm diameter of Ancer group have the highest fracture resistance value when compared with the same diameter of JJ Orthodontics and SK Surgicals. Implants with higher diameter have more resistance than those with lower diameter. Conclusions: The observed highest fracture resistance is 47 Ncm by Ancer and least fracture resistance is 16 Ncm by JJ Orthodontics. The values are higher than the torque required to place mini-implants intraorally. Ancer mini-implants have the highest peak fracture torque, thus more than SK Surgicals and JJ Orthodontics.

The Effect of Osseodensification Technique on Primary Stability of Dental Implants

Purpose: To evaluate the primary and secondary stability when using densah bur in comparison to conventional drilling technique.Methodology: This experimental study was conducted on four dogs using split-mouth fashion so that each side will receive two implants with two different implant-site preparation techniques. In the study group, Densah Bur was used to osseodesify the osteotomy site where conventional cutting drills were used in the control group. The Peak Insertion Torque was used as an evaluation method of primary stability while the Resonance Frequency Analysis was used for both primary and secondary stability.Results: In this study, we collected our measurements via two methods. First, regarding the Peak Insertion Torque, the primary stability was (41 ± 1.2) in the study group, while in the control group, it was (35 ± 1.3) which reveals that the primary stability of the Densah Bur group outweighs the control group with a P-value of (0.003).Second, concerning the Resonance Frequency Analysis, the primary stability of the study group was (85 ± 2.2) while in the control group, the result was (75 ± 1.16) and the P-value of this test (0.0012). On the other hand, the secondary stability was measured by the same device and revealed (85 ± 3.5) of the study group while it shows (71 ± 3.17) in the control group with a P-value of (0.005).Conclusion: From the resulted data, this study verified that the use of osseodensification technique would increase primary stability this could be attributed to the enhancement of bone quality and bone-implant contact by preserving the bulk of bone.

Enhancing primary implant stability by undersizing implant site preparation: A human cadaver study

IntroductionThe aims of this human cadaver study were to analyze the primary stability of dental implants inserted by using different methods of preparation and to explore correlations among the bone density, peak insertion torque and resonance frequency analysis values. Materials and methodsForty-eight implants were placed into six human cadaver mandibles. The bone density of each implant recipient site was preoperatively measured by using computerized tomography (CT) in Hounsfield Units (HU). Three test groups were created according to the final drill size. The diameters of the final twist drills were 3 mm, 3.4 mm, and 3.8 mm in group T1, group T2, and group T3, respectively. The peak insertion torque and resonance frequency analysis values were recorded. ResultsThe mean bone density, insertion torque, and RFA values were 285 ± 90 HU, 42.8 ± 5 Ncm, and 74 ± 6 ISQ for all 48 implants, respectively. Statistically significant correlations were noted between bone density and insertion torque values (P < 0.05), bone density and RFA values (P < 0.01), and insertion torque and RFA values (P < 0.001). When considering the three test groups, the mean insertion torque, and RFA values were 47.1 ± 3 Ncm, and 83.1 ± 6 ISQ in Group T1, and 43.4 ± 5 Ncm and 73.4 ± 6 ISQ in Group T2, and 37.9 ± 6 Ncm, and 65.3 ± 5 ISQ in Group T3. ConclusionThe results of this study suggest that undersized implant site preparations may be helpful in enhancing primary implant stability and that there are significant correlations among bone density, maximum insertion torque, and RFA values.

Correlation of cone beam CT-derived bone density parameters with primary implant stability assessed by peak insertion torque and periotest in the maxilla

PurposePrimary implant stability is crucial to osseointegration. The aim of this study was to assess correlation of preoperative radiologic parameters with intraoperatively obtained biomechanical tests in the maxilla. Materials and methodsA total of 259 implants were inserted in the maxilla of 99 patients. Cone-beam computed tomography (CBCT)-derived Hounsfield units (HU), voxel grey values and computed tomography mental index (CTMI) performed preoperatively were correlated with insertion torque and Periotest (obtained intraoperatively and 12 weeks later) to assess their prognostic value for primary implant stability. ResultsVoxel grey values and insertion torque showed a low correlation (r = 0.329, p = 1.055×10−7 ). Likewise, a low correlation was found between HU measured preoperatively and insertion torque as well as intraoperative Periotest values (r = 0.297, p = 4×10−6 and r = − 0.234, p = 4.35×10−4, respectively). A moderate correlation could, however, be assessed between insertion torque and intraoperative as well as Periotest values 12 weeks later. (r = −0.555, p = 1.022×10−20 and −0.465. p = 1.150×10−13). On contrast, a high correlation was observed between the voxel grey values of CBCT and related HU (r = 0.710, p = 6.486×10−37 ) so that a conversion from grey values into HU could be suggested. According to regression analysis, an intraoperative negative Periotest value could be expected at an insertion torque of 40 N/cm upwards. ConclusionCBCT-based bone density parameters correlate with each other and allow conversion of grey scales into HU preoperatively. Both insertion torque and Periotest showed a significant correlation which enables regression analysis to predict implant stability for related insertion torque. On contrast, for HU the distribution curves do not allow a reliable assignment into certain Periotest values.

Practice-Based Clinical Evaluation of Dental Implants Placed with Immediate or Delayed Loading Protocols: One-Year Follow-Up.

We evaluate bone remodeling and prostheses survival of immediately provisionalized with occlusal loading and delayed loading (DL) single implants placed in the posterior region after 1-yr follow-up in dental practices. Included in the study are patients selected to receive one regular implant (4 × 10 mm) for single tooth replacement in healed ridge sockets in the mandible and maxilla. Implants are immediately loaded or delayed functionally loaded with metal ceramic crowns, depending on peak insertion torque value. All implants are clinically and radiographically evaluated at T1, immediately postoperatively; T2, 60 d; T3, 180 d; and T4, 360 d. Measurements between implant platform and top of alveolar bone crest at distal and mesial areas are performed using periapical radiographs. Data are statistically evaluated through two-way repeated measures of analysis of variance following post hoc comparisons using the Tukey test (p < 0.05). Ten specialists working in ten different practices treat 36 patients who receive one implant each with internal conical connection (hybrid implant system, 4 × 10 mm) (Emfils; Itu, Brazil). Results show that bone-level alterations in immediate (IM; 0.56 mm; confidence interval [CI]: ± 0.21 mm) and delayed (0.65 mm; CI: ± 0.19 mm) groups are not significantly different (p = 0.515) during the course of the 1-yr observation period. In both groups, statistically significant progressive bone-level remodeling occurs through the evaluated follow-up time points (p < 0.047). All prostheses are rated "alpha," presenting 100% success at 1-yr follow-up. The loading method does not influence bone-remodeling levels around IM or DL at the posterior region after 1-yr follow-up. No prostheses complications are reported.

Determination of Implant Primary Stability : A Comparison of the Surgeon’s Tactile Sense and Objective Measurements

Background: Evaluation and measurement of primary stability could be achieved by several methods, including the resonance frequency analysis (RFA) and implant insertion torque (IT) values. The need for a sufficient primary stability, guaranteed by an adequate insertion torque and implant stability quotient values, increased its importance mainly in one stage implants or in immediate loading protocols. The aims of this study was to find if there is a correlation between the peak insertion torque (PIT) and ISQ values of implants inserted in the jaws of different bone quality which regarded as two important clinical determinant factors for prediction of implant primary stability, and to evaluate and compare whether an experienced clinician could precisely predict the primary stability of an implant on insertion with different surgical procedures using his own tactile perception. Materials and methods: A total of (60) Iraqi adult patients, (28) males and (32) females, age ranged (22-66) years old were enrolled in this clinical prospective study. The maximum torque value recorded on implant insertion using calibrated manual torque ratchet adopting three categories: low (10 to 30 N/cm), medium (30 to 50 N/cm), and high insertion torque (50 to 70 N/cm). The oral surgeon was asked to indicate the perceived ISQs values according to his perception then Implant stability quotient were measured by Osstell ™. Bone density (type) was determined according to subjective bone resistance encountered while drilling as proposed by Lekohlm and Zarb. Results: A total of 160 implants were inserted. The mean peak IT value was 49 ± 2.61N/cm. The mean ISQ value was 71.7 ± 8.86. Statistical analysis show a significant correlation between ISQ values and PIT values (P

Influence of Stepped Osteotomy on Primary Stability of Implants Inserted in Low-Density Bone Sites: An In Vitro Study.

The aims of this study were to evaluate the ability of a stepped osteotomy to improve dental implant primary stability in low-density bone sites and to investigate possible correlations between primary stability parameters. The study was performed on fresh humid bovine bone classified as type III. The test group consisted of 30 Astra Tech EV implants inserted following the protocol provided by the manufacturer. The first control group consisted of 30 Astra Tech EV implants inserted in sites without the underpreparation of the apical portion. The second control group consisted of 30 Astra Tech TX implants inserted following the protocol provided by the manufacturer. Implant insertion was performed at the predetermined 30 rpm. The insertion torque data were recorded and exported as a curve; using a trapezoidal integration technique, the area underlying the curve was calculated: this area represents the variable torque work (VTW). Peak insertion torque (pIT) and resonance frequency analysis (RFA) were also recorded. A Mann-Whitney test showed that the mean VTW was significantly higher in the test group compared with the first control and second control groups; furthermore, statistical analysis showed that pIT also was significantly higher in the test group compared with the first and second control groups. Analyzing RFA values, only the difference between the test group and second control group showed statistical significance. Pearson correlation analysis showed a very strong positive correlation between pIT and VTW values in all groups; furthermore, it showed a positive correlation between pIT and RFA values and between VTW and RFA values only in the test group. Within the limitations of an in vitro study, the results show that stepped osteotomy can be a viable method to improve implant primary stability in low-density bone sites, and that, when a traditional osteotomy method is performed, RFA presents no correlation with pIT and VTW.

Intraoral radiographs texture analysis for dental implant planning

Background and ObjectivesComputer vision extracts features or attributes from images improving diagnosis accuracy and aiding in clinical decisions. This study aims to investigate the feasibility of using texture analysis of periapical radiograph images as a tool for dental implant treatment planning. MethodsPeriapical radiograph images of 127 jawbone sites were obtained before and after implant placement. From the superimposition of the pre- and post-implant images, four regions of interest (ROI) were delineated on the pre-implant images for each implant site: mesial, distal and apical peri-implant areas and a central area. Each ROI was analysed using Matlab® software and seven image attributes were extracted: mean grey level (MGL), standard deviation of grey levels (SDGL), coefficient of variation (CV), entropy (En), contrast, correlation (Cor) and angular second moment (ASM). Images were grouped by bone types—Lekholm and Zarb classification (1,2,3,4). Peak insertion torque (PIT) and resonance frequency analysis (RFA) were recorded during implant placement. Differences among groups were tested for each image attribute. Agreement between measurements of the peri-implant ROIs and overall ROI (peri-implant + central area) was tested, as well as the association between primary stability measures (PIT and RFA) and texture attributes. ResultsDifferences among bone type groups were found for MGL (p = 0.035), SDGL (p = 0.024), CV (p < 0.001) and En (p < 0.001). The apical ROI showed a significant difference from the other regions for all attributes, except Cor. Concordance correlation coefficients were all almost perfect (ρ > 0.93), except for ASM (ρ = 0.62). Texture attributes were significantly associated with the implant stability measures. ConclusionTexture analysis of periapical radiographs may be a reliable non-invasive quantitative method for the assessment of jawbone and prediction of implant stability, with potential clinical applications.

Correlation between resonance frequency, insertion torque and bone-implant contact in self-cutting threaded implants.

The aim of this study was to evaluate the correlation between resonance frequency analysis (RFA) values and the histomorphometric bone-implant contact (BIC) immediately after insertion of the implant. Additionally, it was examined to define which extent peak insertion torque (PIT) was correlated with the latter measurements. 15 Xive® S plus root from dental implants were inserted in fresh porcine frontal bones. The insertion torque was measured with the Kavo Intrasurg 300 surgical unit. RFA connector was coupled to the implants and the mean value of 20 consecutive RFA measurements was calculated via Osstell® ISQ device. The implants were removed with the adjacent bone with a band saw. The blocks were processed for undecalcified histology. Two perpendicular longitudinal middle sections of the implant were made and stained with toluidine blue and the BIC was assessed by histomorphometry. The correlation coefficient (Spearman) between RFA and BIC was R=0.579 (p=0.026, F test). The correlation between PIT and BIC (0.33, p>0.05) and PIT and RFA (0.153, p>0.05) was not statistically significant. The present data confirmed a moderate and statistically positive correlation between RFA and BIC. No correlation between BIC and PIT and PIT and RFA was observed. Further studies considering different bone qualities would be beneficial in understanding the relation between RFA and BIC.

A Randomized Case-Series Study Comparing the Stability of Implant with Two Different Surfaces Placed in Fresh Extraction Sockets and Immediately Loaded.

Background. Hydrophilic and moderately rough implant surfaces have been proposed to enhance the osseointegration response. Aim. The aim of this study was to compare early changes of stability for two implants with identical macrodesign but with different surface topographies. Materials and Methods. In 11 patients, a total of 22 implants (11 bimodal (minimally rough, control) and 11 proactive (moderately rough and hydrophilic, test), Neoss Ltd., Harrogate, UK) were immediately placed into fresh extraction sockets and immediately loaded. The peak insertion torque (IT) was measured in Ncm at placement. Resonance Frequency Analysis (RFA) measurements were made at baseline and 2, 4, 6, and 12 weeks after surgery. Results. The two implant types showed similar IT and RFA values at placement (NS). A dip of RFA values after 2 weeks followed by an increase was observed, where the test implant showed a less pronounced decrease and a more rapid recovery than the control implant. The test implants were significantly more stable than the control ones after 12 weeks. Conclusions. The results from the present study indicated that the hydrophilic and rougher test implant was more resistant to immediate loading and showed a significantly higher stability than the smoother control implant after 12 weeks.

Can we predict the insertion torque using the bone density around the implant?

The purpose of this study was to examine the correlation between initial stability and bone density in patients undergoing implant treatment. Twenty-five screw-type dental implants were inserted in 12 patients. All patients underwent multi-detector computed tomography (CT) examination prior to implant insertion. The implant sockets were prepared according to the drilling protocol, and peak insertion torque values were measured. CT values around the implants were measured using preoperatively scanned CT data, which were combined with actual implant positions. Spearman's rank correlation coefficient was used to investigate the correlation between insertion torque values and CT values (in Hounsfield units, HU). Twenty-three implants (8 or 10mm in length) were inserted in the mandibular molar region and two (10mm length) in the maxillary molar region. The mean CT value of the 8-mm implants was 508.6±187.0HU and mean insertion torque was 27.2±12.1N·cm; for the 10-mm implants, these values were 579.6±224.3HU and 28.1±14.6N·cm, respectively. Statistical analysis revealed a strong positive correlation between the insertion torque and mean CT values (r=0.699, 8mm; r=0.771, 10mm). The results revealed that bone density around the implant is a useful index. This study indicates that preoperative CT may enable the prediction of initial implant stability.

Early loading of splinted implants supporting a two‐unit fixed partial denture in the posterior maxilla: 13‐month results from a randomized controlled clinical trial of two different implant systems

The aim of this study was to evaluate early-loaded implants supporting a two-unit fixed dental prosthesis in the posterior maxilla and to compare the clinical and radiological outcomes of two different implant systems in terms of success rates, implant stability quotient (ISQ) values, and peri-implant parameters. Thirty patients with the unilateral loss of two consecutive maxillary posterior teeth were randomly assigned to two different implant systems: SLActive Bone level implant (Institut Straumann AG, Basel, Switzerland) in the control group and CMI IS-II active implant (Neobiotech Co., Seoul, Korea) in the experimental group. The patients received provisional and definitive two-unit fixed prostheses at 4weeks and 6months after implant surgery, respectively. The peak insertion torque was recorded at surgery. The stability of each implant was evaluated during surgery and at 2, 3, and 4weeks and 6 and 13months after implant placement by means of ISQ values. In addition, periapical radiographs and peri-implant parameters were taken throughout the trial. Overall, comparable results were obtained between the control and experimental groups in terms of insertion torque, ISQ values, marginal bone loss, and peri-implant soft tissue parameters. All 60 implants had 100% of success rate. The average insertion torque was 36.83 ± 6.09 (control) and 35.33 ± 3.20 (test) Ncm. The ISQ values remained steady until 4weeks and then increased with statistical significance during 4weeks to 13months after surgery. Both groups exhibited no stability dip during the early phase of healing. The average marginal bone loss from the baseline of implant placement for the control and experimental groups was 0.38 and 0.45mm after 4weeks and 0.98 and 0.61mm after 13months. All of the soft tissue parameters were within normal limits. The results of this study indicate that the concept of early loading at 4weeks after placement in the posterior maxilla can be an effective treatment option, even in the areas of low bone density, when implants satisfy the inclusion criteria of minimum insertion torque and ISQ of 30Ncm and 65, respectively.

Correlation between Initial BIC and the Insertion Torque/Depth Integral Recorded with an Instantaneous Torque-Measuring Implant Motor: An in vivo Study.

Quantitative intraoperative evaluation of bone quality at implant placement site and postinsertion implant primary stability assessment are two key parameters to perform implant-supported rehabilitation properly. A novel micromotor has been recently introduced allowing to measure bone density at implant placement site and to record implant insertion-related parameters, such as the instantaneous, average and peak insertion torque values, and the insertion torque/depth integral. The aim of this study was to investigate in vivo if any correlation existed between initial bone-to-implant contact (BIC) and bone density and integral values recorded with the instrument. Twenty-five patients seeking for implant-supported rehabilitation of edentulous areas were consecutively treated. Before implant placement, bone density at the insertion site was measured. For each patient, an undersized 3.3 × 8-mm implant was placed, recording the insertion torque/depth integral values. After 15 minutes, the undersized implant was retrieved with a 0.5 mm-thick layer of bone surrounding it. Standard implants were consequently placed. Retrieved implants were analyzed for initial BIC quantification after fixation, dehydration, acrylic resin embedment, sections cutting and grinding, and toluidine-blue and acid fuchsine staining. Correlation between initial BIC values, bone density at the insertion site, and the torque/depth integral values was investigated by linear regression analysis. A significant linear correlation was found to exist between initial BIC and (a) bone density at the insertion site (R = 0.96, explained variance R(2) = 0.92) and (b) torque/depth integral at placement (R = 0.81, explained variance R(2) = 0.66). The system provided quantitative, reliable data correlating significantly with immediate postinsertion initial BIC, and could therefore represent a valuable tool both for clinical research and for the oral implantologist in his/her daily clinical practice.

The Influence of Tactile Perception on Classification of Bone Tissue at Dental Implant Insertion.

Various ways of using the Lekholm and Zarb (L&Z) classification have added to the lack of scientific evidence of the effectiveness of this clinical method in the evaluation of implant treatment. The study aims to assess subjective jawbone classifications in patients referred for implant treatment, using L&Z classification with and without surgeon's hand perception at implant insertion. The association between bone type classifications and quantitative parameters of primary implant stability was also assessed. One hundred thirty-five implants were inserted using conventional loading protocol. Three surgeons classified bone quality at implant sites using two methods: one based on periapical and panoramic images (modified L&Z) and one based on the same images associated with the surgeon's tactile perception during drilling (original L&Z). Peak insertion torque and implant stability quotient (ISQ) were recorded. The modified and original L&Z were strongly correlated (rho = 0.79; p < .001); Wilcoxon signed-rank test showed no significant difference in the distribution of bone type classification between pairs using the two methods (p = .538). Spearman correlation tested the association between primary stability parameters and bone type classifications (-0.34 to -0.57 [p < .001]). Tactile surgical perception has a minor influence on rating of subjective bone type for dental implant treatment using the L&Z classification.

The effect of implant design and bone quality on insertion torque, resonance frequency analysis, and insertion energy during implant placement in low or low- to medium-density bone.

This study investigated the effect of implant design and bone quality on insertion torque (IT), implant stability quotient (ISQ), and insertion energy (IE) by monitoring the continuous change in IT and ISQ while implants were inserted in artificial bone blocks that simulate bone of poor or poor-to-medium quality. Polyurethane foam blocks (Sawbones) of 0.16 g/cm³ and 0.32 g/cm³ were respectively used to simulate low density and low- to medium-density cancellous bone. In addition, some test blocks were laminated with a 1-mm 0.80 g/cm³ polyurethane layer to simulate cancellous bone with a thin cortical layer. Four different implants (Nobel Biocare Mk III-3.75, Mk III-4.0, Mk IV-4.0, and NobelActive-4.3) were placed into the different test blocks in accordance with the manufacturer's instructions. The IT and ISQ were recorded at every 0.5-mm of inserted length during implant insertion, and IE was calculated from the torque curve. The peak IT (PIT), final IT (FIT), IE, and final ISQ values were statistically analyzed. All implants showed increasing ISQ values when the implant was inserted more deeply. In contrast to the ISQ, implants with different designs showed dissimilar IT curve patterns during the insertion. All implants showed a significant increase in the PIT, FIT, IE, and ISQ when the test-block density increased or when the 1-mm laminated layer was present. Tapered implants showed FIT or PIT values of more than 40 Ncm for all of the laminated test blocks and for the nonlaminated test blocks of low to medium density. Parallel-wall implants did not exhibit PIT or FIT values of more than 40 Ncm for all of the test blocks. NobelActive-4.3 showed a significantly higher FIT, but a significantly lower IE, than Mk IV-4.0. While the existence of cortical bone or implant designs significantly affects the dynamic IT profiles during implant insertion, it does not affect the ISQ to a similar extent. Certain implant designs are more suitable than others if high IT is required in bone of poor quality. The manner in which IT, IE, and ISQ represent the implant primary stability requires further study.

Estimation of pedicle screw fixation strength from probe indentation force and screw insertion torque: a biomechanical study on bone surrogates of various densities.

Posterior pedicle screw fixation is commonly used for patients with spinal disorders. However, failure of fixation is reported in many cases and surgeons have only little information. The objective of this study was to assess the correlation between the probe indentation force, screw insertion torque and the pullout force using bone surrogates of different densities. The indentation force and insertion torque were measured using a custom made test bench during screw insertion into polyurethane foam blocks. The two variables were significantly correlated to pullout force and to density. A high correlation was also found between indentation force and the peak insertion torque. The proposed methods for measuring indentation force and screw insertion torque were reproducible. This study suggests that the peak screw insertion torque and the indentation force can predict the screw fixation strength in synthetic bone models. Additional tests should be performed on animal and human specimens to confirm and to translate these findings to clinical applications.

Evaluation of a Novel Cone Beam Computed Tomography Scanner for Bone Density Examinations in Preoperative 3D Reconstructions and Correlation with Primary Implant Stability

Bone density examination (BDE) using preoperative cone beam computed tomography (CBCT) might be used to predict primary implant stability in implant patients. The aim of the study was to validate a novel CBCT scanner in vitro with regard to BDE in preoperative scans and to analyze the in vivo correlation of CBCT scan results with primary implant stability measurements. A CBCT scanner was validated in vitro with regard to spatial uniformity and linearity of CT numbers (Hounsfield units, HU) by using a series of phantoms and plastic and hydroxyapatite specimens of various densities. Forty-nine patients (27 female and 22 male, mean age 55.6 ± 9.8) were scanned prior to and 1 to 6 months after the placement of 155 dental implants of different lengths and diameters. Mean and peak insertion torque (IT) in Ncm were registered during implant placement. Resonance frequency analysis (RFA) measurements in ISQ units were performed after placement. The second scan was used to export and superimpose the exact positions of bone and implants into the first scan. Virtual probes with the same length as the actual implant were automatically placed at the implant sites, and mean HU values were measured in a 1 mm-wide circular corridor from the tip of the threads and out. The in vitro validation showed high uniformity and linearity of CT numbers (HU). The clinical study showed significant correlations between bone density and ISQ, mean IT, and peak IT, respectively. The WhiteFox CBCT scanner measures bone density with high accuracy. There is a correlation between bone density and primary implant stability as assessed with IT and RFA measurements. The findings suggest that BDE may be used as an additional feature in treatment-planning software to estimate primary stability at predetermined implant sites.

Peak insertion torque values of five mini-implant systems under different insertion loads

To assess the effect of 1 and 3 kg insertion load on five makes of self-drilling mini-implants on peak insertion torque values to establish risk factors involved in the fracture of mini-implants. Two different loads were applied during insertion of 40 mini-implants from five different manufacturers (Dual Top(™) (1·6×8 mm), Infinitas(™) (1·5×9 mm), Ortho Easy(™) (1·7×8 mm), Spider Screw(™) (1·5×8 mm) and Vector TAS(™) (1·4×8 mm)) into acrylic blocks at 8 rev/min utilizing a Motorized Torque Measurement Stand. Peak insertion torque values for both loads were highest for Vector TAS followed by Ortho Easy and Dual Top and were nearly three times higher than Infinitas (original version) and Spider Screws(TM). The log-rank test showed statistically significant differences for both loads for Vector TAS, Ortho Easy and Spider Screws. Unlike other designs tested, both tapered mini-implant designs (Spider Screw and Infinitas) showed a tendency to buckle in the middle of the body but fractured at the tip. Non-tapered mini-implants fractured at significantly higher torque values compared to tapered designs under both loads. Increased pressure resulted in slightly higher maximum torque values at fracture for some of the mini-implant designs, although this is unlikely to be of clinical relevance. Tripling insertion pressure from 1 to 3 kg increased the risk of bending tapered mini-implants before fracture.

T1 Intralaminar Screws: An Anatomic, Morphologic Study of 112 Cadaveric Specimens and the Feasibility of T1 Intralaminar Screw Placement

Laminar screw placement is generally reserved for use as a salvage or alternative technique when pedicle screw placement is contraindicated in the setting of a complex revision, tumor, or anomolous anatomy. Pedicle screws have proven to be the most biomechanically stable screws, but laminar screws are a reliable alternative when necessary. The mean pullout forces between laminar and pedicle screws are similar; however, the mean lamina screw peak insertion torque is lower than the mean index pedicle screw peak insertion torque. Advantages of laminar screw placement as opposed to pedicle screws include a decrease in possible neurovascular complications secondary to the proximity of these structures to the pedicle. Another important advantage of laminar screw fixation is that the use of a fluoroscope or navigation system is no longer necessary because the screw can be placed under direct vision of the outer cortex of the lamina and all relevant structures. Tactile feedback can also defer violation of the spinal canal.

Bone quality assessment in routine dental implant treatment amongBrazilian andSwedish specialists

To investigate the interpretation and assessment of bone quality among Brazilian and Swedish specialist performing implant treatment. A questionnaire was developed containing open and closed questions on attitudes, knowledge, and understanding of diagnostic methods for bone quality assessment. The questionnaire was sent by mail to dental implant specialists in Brazil while the Swedish version was Web-based and sent to specialists in periodontology and maxillofacial surgery. The response rate in the Brazilian group was 15.4% and in the Swedish group 36.5%. Most respondents in both groups considered bone quality to be an important parameter for implant treatment outcome. Among Swedish specialists, bone quality, however, was considered to be of low relevance. The most popular method for assessing bone quality among Swedish specialists was the hand-felt perception of drilling resistance followed by radiography. The Brazilian specialists more often used peak insertion torque. Most respondents classified bone quality, and both groups used the classification proposed by Lekholm & Zarb (Tissue-Integratedprosthesis: Osseointegration in Clinical Dentistry, 1985, Quintessence, Chicago) most frequently. Specialists in both countries considered bone quality to be an important parameter for implant treatment outcome, but there was no consensus neither on what bone quality means nor on how to assess bone quality.