Insertion Torque Values Research Articles

Recommendations for standardised screw pull-out from polyurethane foam - The influence of density variations of the test foam and the insertion method

Insertion and pull-out tests of synthetic test material are well established for the initial laboratory evaluation of screws. However, not all test parameters are sufficiently described. The influence of small density deviations of the test material, of tapping or of manual or machine insertion has not been fully examined. The aim of the present study was to examine the influence of these specimen preparation parameters on the measurement results in order to increase the reproducibility and reliability of screw pull-out tests. For this purpose, a commercial polyurethane foam and a clinically used type of screw are evaluated with insertion and pull-out tests. Within a foam apparent density grade, small deviations in apparent density led to significant and relevant differences in the measured values of insertion torque and pull-out strength. Furthermore, an influence on the measurement results was found during tapping and during manual or machine insertion of screws. For these reasons, specimens with the same apparent density should be used as far as possible and evenly distributed among the test groups. In addition, the reproducibility of the results can be increased by machine insertion of the screws.

Are the Insertion Torque Value and Implant Stability Quotient Correlated, and If So, Can Insertion Torque Values Predict Secondary Implant Stability? A Prospective Parallel Cohort Study.

Primary stability is the most important prognostic index for predicting osseointegration. It is generally thought that to achieve high primary stability, it is necessary to insert an implant with a high insertion torque (IT). To date, it has not yet been determined whether IT and implant stability quotient (ISQ) values are correlated. The primary aim of the study was to determine the correlation between IT and ISQ values at the time of implant insertion (T0); at 2 months, the time of healing (T1); and at 6 (T2) and 12 months (T3) after loading. The secondary aims were to determine the influence of different macroscopic implant designs and of a different insertion arch on this correlation; and to assess whether implants inserted with a high IT, that is, > 50 Ncm, had higher levels of implant stability at 2-, 6-, and 12-month follow-ups. STROBE guidelines were followed. Partially or monoedentulous patients were randomly assigned to receive taper thread on straight-body implants with microthreads (group A) or without microthreads (group B). At implant insertion, IT and ISQ values were recorded. At 2-, 6-, and 12-month follow-ups, the ISQ values were recorded. A spring-style torque wrench was used to assess the IT. The Osstell device was used to determine the ISQ values. Descriptive statistics, Pearson correlation, and t test were used. P was set at ≤ .005. Two hundred fifty subjects were assessed; 142 were included. Two hundred sixty-eight implants were inserted (group A, 137 implants; group B, 131 implants). No subject dropped out, and no implant failed. A statistically significant correlation between ISQ and IT was determined at the time of implant insertion (T0; P = .000). The implant morphology and arch did not influence the correlation. An IT > 50 did not determine a higher secondary stability. There is a strong correlation between IT and primary stability, but IT is not correlated with the secondary stability. A different implant macroscopic design and a different arch of insertion did not influence this correlation. Moreover, implants inserted with IT > 50 Ncm do not result in greater secondary stability.

Peri-İmplant Kemik Defekti Tipinin Yerleştirme Torku ve Rezonans Frekans Analizi Üzerine Etkisi: İn Vitro Çalışma

Objective: The aim of the present study is to investigate the effects of different peri-implant bone defects on primary stability and the correlation between insertion torque (IT) and resonance frequency analysis (RFA) measurements. Material and Methods: Fourty implant beds were prepared in artificial bone blocks using the 3D surgical guide. Implant osteotomies were divided into 5 groups (n=8) according to defect type: i) no peri-implant bone defect (control), ii) a dehiscence defect, iii) a fenestration defect on the middle part, iv) a fenestration defect on the apical part and v) a circumferential defect. Implants were inserted by using a surgical drilling unit with torque control and RFA measurement were done. Results: IT values for the control group were significantly higher than the other groups (p<0.001). The results of IT measurements for dehiscence defect group were significantly greater when compared to fenestration and circular defect groups (p<0.01). Implant stability quotient (ISQ) values for the control group were significantly higher than other groups (p<0.05). In addition, the ISQ values for the dehiscence defect group were significantly lower when compared to fenestration defect groups (p<0.001), and ISQ values for the circular defect group were significantly lower than any other groups (p<0.001). IT values and, ISQ values are moderately correlated (p=0.013, r=0.388). Conclusion: The location of peri-implant bone defect affects RFA measurements more than IT. However, IT seems to be correlated with bone implant contact. Therefore, in the case of peri-implant bone defect, IT measurement may be preferred for evaluation of primary stability.

The Effect of Bone Density Measured by Cone Beam Computed Tomography and Implant Dimensions on the Stability of Dental Implants.

The aim of this study was to evaluate the effect of bone density value in Hounsfield unit derived from cone beam computed tomography (CBCT), and implant dimensions in relation to implant stability parameters namely the resonance frequency analysis and the insertion torque (IT) value. It included 24 patients who received 42 dental implants (DI). The bone density of the planned implant site was preoperatively measured using cone beam computed tomography. The implant stability was measured using Osstell implant stability quotient (ISQ). The ISQ values were recorded immediately postoperatively and after 16 weeks. The IT value was categorized as 35 N/cm or > 35 N/cm. The mean (standard deviation) primary stability was 79.58 (5.27) ISQ, which was significantly higher than the secondary stability 74.31 (6.34) ISQ ( P < 0.0001). There was a significant moderate positive correlation of bone density with primary stability ( r = 0.4, P = 0.0099) and no correlation with secondary stability ( r = 0.003, P = 0.9867). The bone density of DI with 35 N/cm IT was significantly lower than with > 35 N/cm IT ( P = 0.0390). Better stability was recorded with wider implants. Whereas the length of the DI showed a nonsignificant correlation with primary and secondary stability ( P = 0.7633 and 0.4670, respectively). The DI dimensions showed a nonsignificant correlation with the IT. Cone beam computed tomography may be considered as a reliable method to assess bone density and predict the implant stability. The diameter of DI affected the implant stability favorably, whereas DI length showed no effect.

Influence of Cortical Layer and Surgical Techniques on the Primary Implant Stability in Low-density Bone:An In Vitro Study

This study aimed at evaluating the influence of cortical layer and surgical techniques on the primary stability of implants in low-density bone. Two solid rigid polyurethane blocks with a density equivalent to 0.32 g/cm3 simulating cancellous bone were used. A short fiber-filled epoxy resin sheet of 2 mm was layered to one block to simulate cortico cancellous bone. A total of 40 implants were used in this study (n = 40). Twenty implants each (n = 20) were inserted in cancellous (Group 1) and cortico-cancellous bone (Group 2), of which 10 implants each (n = 10) were placed using undersized preparation technique with surgical drills-A and osteotomes-B, in both the groups. Insertion torque (IT) and implant stability quotient (ISQ) for each implant placed were assessed to determine the primary stability of each implant using a digital torque meter and resonance frequency analyzer, respectively. The values were statistically analyzed using an independent t-test (p < 0.05). Pearson's correlation analysis was performed to correlate between IT and ISQ. Technique B resulted in significantly higher IT and ISQ values in Group 1 (27.69 ± 1.2 N cm; 52.5 ± 1.05 ISQ) and Group 2 (38.8 ± 0.87 N cm; 70.1 ± 1.04 ISQ) compared to those with technique A (22.40 ± 1.62 N cm; 41.75 ± 1.20 ISQ and 33.24 ± 0.67 N cm; 63.72 ± 1.33 ISQ), respectively. Group 2 exhibited significantly higher IT and ISQ values as compared to Group 1 irrespective of the surgical technique employed (p < 0.05). The presence of the cortical layer significantly influenced the primary stability and preparing low-density bone with an undersized preparation technique using osteotomes that significantly increased the IT and ISQ. Undersizing the preparation site considerably will help achieve a significant increase in primary stability in the poor quality bone as in the posterior maxilla, thereby contributing to the success of the implant.

Mechanical stability of orthodontic miniscrew depends on a thread shape

Background/purposePrimary stability of orthodontic miniscrew system is of great importance in maintaining stable anchorage during a treatment period. Thus, this study aimed to examine whether the thread shape of orthodontic miniscrew had an effect on its mechanical stability in bone. Materials and methodsThree different types of miniscrews (type A and B with a regular thread shape; type C with a novel thread shape) were placed in artificial bone block with different artificial cortical bone thickness of 1.5, 2.0 and 3.0 mm. Values of maximum insertion torque (MIT), removal torque (RT), torque ratio (TR), screw mobility, static stiffness (K), dynamic stiffness (K∗) and energy dissipation (tan δ) ability were assessed for each miniscrew system. ResultsThe MIT, RT, TR and K of type C miniscrew were significantly greater than those of type A and B miniscrews when the miniscrews were placed in the thinner artificial bone. Furthermore, the TR value of type C miniscrew was more than 1, indicating the MRT value was larger than the MIT value in the novel miniscrew. The values of K∗ and tan δ were almost similar among the three types of miniscrews. ConclusionThe miniscrew with a novel thread shape showed a higher initial stability compared to those with a regular thread shape. Thus, in order to obtain a sufficient initial stability, it is important to select the type of screw thread that is appropriate for the thickness of the cortical bone.

Accuracy and primary stability of tapered or straight implants placed into fresh extraction socket using dynamic navigation: a randomized controlled clinical trial.

To compare the accuracy and primary stability of tapered and straight implants undergoing immediate implant placement with dynamic navigation. Patients with compromised anterior teeth in maxilla were recruited and allocated randomly into (1) tapered implant group (TI group) and (2) straight implant group (SI group). Implants were inserted into fresh sockets with dynamic navigation. Three-dimensional platform deviation, apex deviation, angular deviation, insertion torque value (ITV) and implant stability quotient (ISQ) were recorded. Twenty patients with 20 implants were included. The overall platform, apex, and angular deviation were 0.87 ± 0.35mm, 0.81 ± 0.34mm, and 2.40 ± 1.31°, respectively. The accuracy was 0.86 ± 0.26mm, 0.76 ± 0.33mm, and 2.49 ± 1.54° for TI, and 0.89 ± 0.44mm, 0.88 ± 0.36mm, and 2.31 ± 1.01° for SI, with no significant difference (p = 0.85, 0.45, 0.76). Sagittal root position classification (SRP) class I may obtain greater error in numerical values in straight implants (0.97 ± 0.47mm vs. 0.6 ± 0.16mm, 0.92 ± 0.36mm vs. 0.73 ± 0.36mm, 2.48 ± 1.19° vs. 1.71 ± 0.14°). The overall ISQ was 60.74. ISQ was 60.48 for TI and 60.96 for SI, with no significant difference. Acceptable ITV (> 15Ncm) was achieved in most of the included patients (SI 7/10, TI 9/10). High accuracy and primary stability of immediate implant placement could be achieved both in tapered and straight implants with dynamic navigation systems. Tapered and straight implants did not reach a consensus on which was better in immediate implant regarding to accuracy and primary stability. Our study demonstrated implant macrodesign did not affect accuracy and primary stability in immediate implant using dynamic navigation.

Evaluation of clinical parameters for the stability of 2 types of miniscrews

The purpose of this research was to compare insertion techniques and effects on mechanical and clinical parameters between 2 types of miniscrews. Forty-four consecutive patients whose orthodontic treatment involved the use of miniscrews (miniscrew A [MA] and miniscrew B [MB]) for anchorage were included in this study. Miniscrews were placed with predrilling or self-drilling; peak maximum insertion torque (MIT) and Periotest values were measured. Cone-beam computed tomography was performed after the insertion of miniscrews and root proximity determination; cortical bone thickness was also analyzed. Periotest values were measured after the application of orthodontic force. Self-drilling produced higher Periotest values (P<0.01) for MA and higher MIT (P<0.01) for MB with closer root proximity (P<0.05). MB had higher MIT and Periotest values with drilling compared with MA (P<0.05); MB also showed closer root proximity (P<0.05). Successful miniscrews had lower MIT (P<0.05) for MB and lower Periotest values (P<0.01) for both MA and MB, with significantly more distant root proximity (P<0.01). Self-drilling produced higher Periotest values at the time of placement (P<0.01) and after 4 weeks (P<0.05) in MA. Drilling produced higher Periotest values for MB at the time of placement (P<0.05). MIT had positive correlations with Periotest values for MB with self-drilling (P<0.01) and with root proximity for MA with drilling (P<0.01). Periotest values had negative correlations with root proximity for MA and the MB group with drilling (P<0.01). For miniscrews with larger diameters, higher MIT may result in more mobility (higher Periotest values). Drilling can avoid root contact and enhance primary stability, thus producing lower Periotest values.

Correlation between insertion torque and peri-implant bone strain during placement of orthodontic mini-implants: A finite element study

Insertion torque is the amount of torque exerted on the implant to tighten into the bone. We investigated whether insertion torque values could be correlated with the strain level in the peri-implant cortical bone resulting from mini-implant insertion. The insertion of a standard size mini-implant (φ1.4mm×7mm) into maxillary alveolar bone was simulated using the finite element method. A total of 3600 calculation steps were employed to numerically reproduce the mini-implant insertion process and analyze the insertion torque and strain distribution in bone. Special attention was given to the relationship between insertion torque values and strain level in the cortical bone at the final tightening. The strain level was quantified using the following 3 strain parameters: (1) average insertion strain, (2) peak insertion strain recorded near the mini-implant thread tips, and (3) the size of the damage zone in the cortical bone. Correlations between the insertion torque values and these 3 parameters were analyzed using linear regression. Direct proportionality and strong correlation were found between the insertion torque values and each of the 3 strain parameters: average insertion strain (r2=0.91), peak insertion strain (r2=0.91), and the size of damage zone (r2=0.90) in the peri-implant cortical bone. The results of this finite element method study demonstrated that insertion torque could serve as a reliable indicator of the strain level in the peri-implant cortical bone resulting from mini-implant insertion.

Can the design of the instruments used for undersized osteotomies influence the initial stability of implants installed in low-density bone? An in vitro pilot study.

ObjectivesThe aims of this study were to compare the initial implant stability obtained using four different osteotomy techniques in low-density synthetic bone, to evaluate the instrument design in comparison to the implant design, and to determinate a possible correlation between the insertion torque and initial stability quotient (ISQ).Materials and methodsFour groups were identified in accordance with the osteotomy technique used (n = 10 implants per group): group G1, osteotomy using the recommended drilling sequence; group G2, osteotomy using an undersized compactor drill; group G3, osteotomy using an undersized drill; and group G4, osteotomy using universal osseodensification drills. Two polyurethane blocks were used: block 1, with a medullary portion of 10 pounds per cubic foot (PCF 10) and with a 1 mm cortical portion of PCF 40, and block 2, with a medullary of PCF 15 and with a 2 mm cortical portion of PCF 40. Tapered implants of 4 mm in diameter and 11 mm in length were used. The insertion torque (IT) and ISQ were measured. The dimensions of the final instrument used in each group and the dimensions of the implant were used to calculate the total area of each part, and these data were compared.ResultsDifferences between the four groups were found for IT and ISQ values depending on the technique used for the osteotomy in the two synthetic bone models (p < 0.0001). All groups showed lower values of initial stability in block 1 than in block 2.ConclusionsUndersized osteotomies with instruments designed according to the implant body significantly increased the initial stability values compared to beds prepared with universal drills and using the drilling sequence standardized by the manufacturer.

Staged Sinus Floor Elevation Using Novel Low-Crystalline Carbonate Apatite Granules: Prospective Results after 3-Year Functional Loading.

The aim of this study was to evaluate clinical outcomes of staged sinus floor elevation (SFE) using novel low-crystalline carbonate apatite (CO3Ap) granules. Patients who needed SFE for implant placement were recruited into this clinical trial. A staged procedure (lateral window technique using CO3Ap granules, followed by implant placement after 7 ± 2 months) was employed in 13 patients. Bone-height increase and insertion torque values (ITVs) were assessed along with histological evaluation. The survival and success rates of 3-year functioning implants were also evaluated. Mean of bone-height increase after SFE using CO3Ap granules was 7.2 ± 2.5 mm and this increase allowed implant placement in all cases (17 implants). Mean of ITV was 25.1 ± 13.2 Ncm and primary stability was achieved successfully in all cases. Histological analyses revealed mature new bone formation (36.8 ± 17.3%) and residual CO3Ap granules (16.2 ± 10.1%) in the compartment after SFE. The survival and success rates after 3-year functional loading were 100% and no complications were found. These results clearly indicate the clinical usefulness of CO3Ap granules for SFE.

Are Lower Insertional Torque Values Associated with Increased Early Dental Implant Failures?

Statement of the problemThe purpose of this retrospective cohort study was to determine whether low insertional torque vales < 30-Ncm were associated with increased early dental implant failures. Materials and methodsA retrospective cohort study was conducted to evaluate dental implants placed in 2015 at the VA North Texas Health Care System in Dallas. The following inclusion criteria were defined: 1) patients who were not lost to follow-up within the first 6 months of implant placement; 2) cases with sufficient medical records, including pre-surgical and post-surgical evaluation. Patients were excluded as study subjects if: 1) they had inadequate medical records; 2) they were a current tobacco smoker or were undergoing treatment for systemic conditions such as bisphosphonate use, head and neck radiation, and chemotherapy. The primary predictor variable was dental implant insertional torque, measured at the time of implant placement as: < 30-Ncm, 30-39-Ncm, 40-49-Ncm, 50-59-Ncm, 60-69-Ncm, and > 60-Ncm. The primary outcome variable was early implant failure, defined chronologically as implant failure necessitating explantation within 6 months of placement.1 Secondary predictor variables were age ≥ 65 years and sex, defined as male or female. Descriptive, bivariate, and multiple logistic regression analyses were performed with P < .05 used to determine statistical significance. Results and outcomesThirty-three subjects and 69 implants met the defined inclusion and exclusion criteria. The average age of the cohort was 65 years. Sixty-two implants were placed in males, and 7 were placed in females. There was a total of 5 early failures (7%). Four occurred in males, and 1 occurred in a female. Four occurred in subjects ≥ 65, and 1 occurred in a subject < 65. Two early failures occurred with an insertional torque < 30-Ncm, 1 occurred with an insertional torque of 30-39-Ncm, and 2 occurred with an insertional torque of 50-59-Ncm. Analysis of the predictor variable and primary outcome variable revealed that decreased insertional torque values resulted in an increase in early dental implant failures and was statistically significant (P = .034). Specifically, insertional torque values below the threshold of 30-Ncm resulted in a 14-fold increase in early failures (OR 14.66; 95% CL 1.74-123.51). Analysis of the secondary predictor variables, age and sex, revealed no statistically significant differences with P = 1.00 and P = .4242, respectively. Discussion and conclusionThe results of this retrospective cohort study suggest that decreased insertional torque values of dental implants below 30-Ncm increase early failure rates within 6 months of dental implant placement. A systematic review by Oliveira et al found that there was not strong enough evidence to conclude that insertional torque < 30-Ncm established enough primary stability between the implant and surrounding bone. They concluded that this decreased primary stability decreased overall implant survival.2 The results of this present study suggest that a low insertional torque value < 30-Ncm decreases the primary stability of the implant in the surrounding bone, thereby increasing the rate of early dental implant failure. Future prospective studies by this group will be performed to further elucidate the association between insertional torque and early dental implant failure.

An In Vitro Analysis on Polyurethane Foam Blocks of the Insertion Torque (IT) Values, Removal Torque Values (RTVs), and Resonance Frequency Analysis (RFA) Values in Tapered and Cylindrical Implants

Background: Several different dental implant microgeometries have been investigated in the literature for use in low-density bone sites. The polyurethane solid rigid blocks represent an optimal in vitro study model for dental implants, because their composition is characterized by symmetrical linear chains of monomers of hexa-methylene sequences producing a self-polymerization process. The aim of the present investigation was to evaluate the primary stability of cylindrical and tapered implants positioned into low-density polyurethane solid rigid blocks. Materials and Methods: Two different macrogeometries, cylindrical (4 mm diameter and 10 mm length) and tapered dental implants (4.20 mm diameter and 10 mm length), were investigated in the present study. The implants were inserted into 10 PCF and 20 PCF polyurethane blocks, with and without an additional cortical layer. The insertion torque (IT) values, the removal torque values (RTVs), and the resonance frequency analysis (RFA) values were measured and recorded. Results: A total of 80 sites were tested, and a significant increased primary stability (PS) was detected in favour of tapered dental implants when compared to cylindrical implants in all experimental conditions (p < 0.05). Higher IT, RT, and RFA values were measured in tapered implants in 10 and 20 PCF polyurethane blocks, both with and without the additional cortical layer. Conclusions: Both implants showed sufficient primary stability in poor density substrates, while, on the other hand, the tapered microgeometry showed characteristics that could also lead to clinical application in low-density posterior maxillary sites, even with a drastically decreased bone cortical component.

Influences of screw design features on initial stability in immediate implant placement and restoration

BackgroundSelf-tapping screws have been extensively used for dental implants. Their biomechanical behavior is highly associated with their clinical success, particularly for screws used for immediate implant placement and restoration, because occlusal forces can directly affect the loading transfer at the bone–implant interface after implantation. The effect of implant design on the initial stability of self-tapping screws remains unclear. This study explored the biomechanical behaviors of implant stability in standardized implants with different design features. MethodsSix types of dental implants were designed using computer-aided design/computer-aided manufacturing technology, including three types of cutting flute shapes (spiral, straight, and non–self-tapping) combined with two types of screw features. Peak insertion torque values were first recorded; initial stability levels were subsequently evaluated in terms of the maximum force and resistance to lateral loads using an electrodynamic test system. FindingsThe peak insertion torque values, maximum force, and resistance to lateral loads of the non–self-tapping groups were higher than those of the self-tapping groups by 17%–90% (p < 0.01). The peak insertion torque values of the Straumann implant with a spiral flute was higher than that of the original straight flute by 20% (p < 0.001). However, compared with the original spiral flute, the Nobel Biocare implant with straight flute had a 23% higher maximum force (p = 0.016) and 24.5% higher resistance (p = 0.012) under lateral loading. InterpretationChanging the flute design would affect initial implant stability. Non–self-tapping implants exhibited superior initial stability than did self-tapping implants.

Correlation between bone volume fraction in posterior implant area and initial implant stability

Bone volume fraction (BV/TV) was used as a quantitative indicator of bone mineral density (BMD) in the posterior dental implant area, and the relationship between it and the initial stability of the implant was analyzed. 53 patients with posterior dental implantation were selected. Remove the bone fragments from the planting area and put them in the formalin solution. Then, the implant was placed after the operator prepared the hole step by step. Peak Insertion torque value (ITV) and Implant stability quotient (ISQ) were recorded. The BV/TV of the bone fragments was measured by Image pro Plus6.0. The correlation between it and ITV and ISQ was analyzed. BV/TV was correlated with ITV and ISQ in the posterior dental planting area (r=0.862, r=0.832, P < 0.05). The correlation of the parameters in the posterior part of maxilla was higher than that in the mandible. There were significant differences in BV/TV, ITV, and ISQ between the mandible and maxilla, and the implant area of the mandible was higher than that of the maxilla. BV/TV can provide an objective index for BMD in the implant area, which has an important influence on the evaluation of the initial stability of the implant.

Comparative Evaluation of Implant Stability, Insertion Torque, and Implant Macrogeometry in Different Bone Densities Using Resonance Frequency Analysis

Evaluation and comparison of insertion torque (IT) and the implant stability of two different implant macrogeometry in different bone densities using resonance frequency analysis. A total of 48 implants (with two implant types having regular and novel macrogeometry) were classified into 4 groups with 12 samples in each group. Group A regular implant without surface treatment, group B regular implant with surface treating, group C novel implant deprived of surface treating, and group D was new dental implant with surface treatment were used. Implant stability quotient (ISQ), implant IT, removal torque (RT) percentage, and torque reduction percentage were calculated. The mean ± SD ISQ value of bone 1 in group A was 56.7 ± 3.2, in group B was 58.6 ± 2.4, in group C was 57.1 ± 3.5, and in group D was 59.3 ± 2.9. In bone 2, the value was 57.8 ± 1.4, 59.5 ± 1.5, 58.2 ± 2.6, and 59.5 ± 2.4 among A, B, C, and D groups correspondingly. In bone 3, it was 59.4 ± 2.4, 60.3 ± 2.3, 60.4 ± 2.8, and 62.7 ± 2.5 among A, B, C, and D groups correspondingly. In bone 4, it was 67.2 ± 3.4, 69.5 ± 2.7, 68.7 ± 2.4, and 69.4 ± 2.3 among A, B, C, and D groups correspondingly. There was a substantial difference in IT and nonsignificant difference in RT in different groups. There was a low IT value with new implant macrogeometry as compared to regular implant macrogeometry. There was absence of association between IT and implant stability. Calculation of torque insertion score helps in implant placement. Higher bone density scores produce a higher option of decreasing the initial torque. Low IT of new implant types is useful to reduce failure.

HEAT GENERATION DURING IMPLANT PLACEMENT IN HIGH-DENSITY BONE: EFFECT OF DIFFERENT DRILLING TECHNIQUES

ABSTRACT Introduction: A precise drilling-sequence-protocol is essential for long-term dental implant success in high bone density (mandibular cortical bone of D1-quality). Cone beam computed tomography (CBCT) radiographic imaging and CBCT-based construction of surgical guides have been substantial for diagnosis and treatment planning. Objectives: The study aimed to measure the effect of different guided drilling techniques on the amount of heat generated during implant placement in high density. Materials and Methods: Twenty-four osteotomies for implant placement, divided equally into three groups, to test the effect of the three drilling techniques Undersized Drilling (UD), Undersized Drilling + Ridge Spreader size 4 (UD+RS4) and Undersized Drilling + counter sink size 4 (UD+CS4) techniques. Heat generation was assessed using K-type thermocouple. Drilling and thermocouple canals were guided by the surgical template. Bone assessment, virtual planning of the implants and surgical guide construction were based on radiographic CBCT-imaging and software-based processing. Insertion torque values (ITVs) were recorded from readings of a geared motor. Results: The thermocouple results showed the least significant difference at 10 mm depth. At 5mm depth, a significant decrease in the temperature difference of the UD+RS4 group and UD+CS4 group compared to UD group was observed. At 1mm depth, there was a significant difference between the UD group and the two other groups. The UD group showed the maximum peak ITV. Conclusion: the results suggest possible advantages when self-tapping implants are inserted into high density cortical bone of D1-quality by a countersink drill since it provides lesser temperature increase at insertion.

COMPARATIVE EVALUATION OF OSSEODENSIFICATION EFFECT ON PERI-IMPLANT STRAIN WHILE LOADING A FOUR UNIT CERAMIC FIXED PARTIAL DENTURE (IN VITRO STUDY)

Introduction: Primary stability and bone quality are key factors in implant success in early stages of placement while osseointegration comes further on. Objectives: The aim of this study was to compare the effect of osseodensification on peri-implant strain during functional loading of a 4-unit monolithic zirconia bridge as well as its effect on primary stability and insertion torque. Materials and Methods: Sixteen IS-II active implants were used in this study, the implants were divided into 2 groups. Group (A) were placed in conventionally drilled osteotomy sites with progressive subtractive enlargement and Group (B) were placed in osseo-densified osteotomy sites. All implants were inserted in unicortical polyurethane test blocks mimicking medium quality bone while recording insertion torque and implant stability quotient (ISQ) using Osstell for all implants. Each block contained two parallel implants carrying a 4-unit fixed partial denture (FPD). FPD were cemented then thermocycled for 5000/cycle and mechanically loaded at 100N, 2.5×10*5 cycles. A load of 400N and 600N and 800N was applied at connector areas in FPD. Strain gauges were connected to strain meter to record the peri-implant strain for both implants in all groups. Results: Regarding insertion torque and peri-implant insertion torque strain Group (A) had significantly lower values than group B (p < 0.05) while insignificant Osstell values. Concerning peri-implant strain after loading group A had significantly higher strain values than Group (B) (p < 0.05). Conclusions: Osseodensification drilling protocol increased insertion torque values and peri-implant insertion torque strain in comparison to conventional drilling protocol while decreasing peri-implant strain after loading.

Comparative In Vitro Evaluation of the Primary Stability in D3 Synthetic Bone of Two Different Shapes and Pitches of the Implant Threads

Background: Implant primary stability can be affected by several factors related to implant macrogeometry, local anatomy, and surgical techniques. The aim of this research was to study primary stability on polyurethane foam sheets of wide-threaded implant design compared to narrow-threaded implants. Materials and methods: Two different implant designs were positioned on D3 density polyurethane blocks in a standardized environment: the wide-threaded implant and the narrow-threaded implant, for a total of 160 specimens. Moreover, for each group, two different sizes were considered: 3.8 mm × 12 mm and 4.8 mm × 12 mm. The insertion torque (IT) values, the removal strength (RT), and the Periotest analyses were evaluated. Results: A significantly higher IT and RT was reported for wide-threaded implants and two-stage implants (p &lt; 0.01), compared to the narrow-threaded implants. The diameters seemed to provide a significant effect on the primary stability for both implants’ geometry (p &lt; 0.01). A higher mean of the one-stage implant was evident in the Periotest measurements (p &lt; 0.01). Conclusions: Both of the implants showed sufficient stability in polyurethane artificial simulation, while the wide-threaded implant design showed a higher primary stability on alveolar cancellous synthetic bone in vitro. Additionally, the prosthetic joint connection seemed to have a determinant effect on Periotest analysis, and the one-stage implants seemed to provide a high stability of the fixture when positioned in the osteotomy, which could be important for the immediate loading protocol.

Reduction of Insertion Torque on Orthodontic Mini-screw Implant by means of Reduced Friction

In this article, the reduction of insertion torque on the orthodontic mini-screw implants (OMI) was studied. Three types of diamond-like carbon (DLC) films (DLC, Si-DLC, and F-DLC) were deposited on the OMIs by plasma-based ion implantation technique. The maximum insertion torque (MIT) value was measured using a physiodispenser during insertion on a mandibular pig jaw. Ten OMIs of each condition were used to evaluate the MIT values compared to the Ti-6Al-4V typed OMI. The statistical analysis of data was analyzed by One-way analysis of variance (ANOVA) and Tukey HSD. The results indicated that the Ti-6Al-4V showed the highest MIT but not significantly different from the F-DLC (P &gt;0.05). DLC and Si-DLC showed a significant reduction in MIT comparing to the Ti-6Al-4V (P &lt;0.05). However, the Si-DLC showed the lowest MIT among groups (P &lt;0.05). This phenomenon was due to the decreasing friction coefficient during OMI's insertion on a mandibular pig jaw. Therefore, the DLC coating, especially Si-DLC, could reduce the MIT value of OMI. It is thought that the lowering friction coefficient yields the lowering of MIT value. Keywords: Diamond-like carbon, Friction, Insertion torque, Mini-screw implant