Influence of the orientation of the Osstell® transducer during measurement of dental implant stability using resonance frequency analysis: A numerical approach

Laser resonance frequency analysis of pedicle screw stability: A cadaveric model bone study

There is no evaluation method currently available to assess intraoperative pedicle screw fixation (PSF) strength. In this study, we established a laser-based resonance frequency analysis (RFA) system with high-speed, noncontact, quantitative measurements of PSF. Clinical investigations in the future can assess surgical failure risk of implants. We investigated the characteristics of the laser RFA and compared them with the conventional methods. We inserted a pedicle screw in the vertebral pedicle of human cadaver or model bone, followed by screw pull-out, peak torque, implant stability quotient (ISQ) value obtained by the magnetic dental RFA system, and fixation force of laser RFA. We compared the outcomes using best-fit linear or logarithmic approximations. For the model bone study, the resonance frequency (RF) versus peak torque/pull-out force (POF) demonstrated strong correlations using logarithmic approximation (vs. peak torque: R = 0.931, p < .001, vs. POF: R = 0.931, p < .001). RF strongly correlated with the ISQ value using linear approximation (R = 0.981, p < .001). For the cadaveric vertebrae study, the correlation coefficients between RF and the peak torque/POF were significant regardless of approximation method (peak torque: logarithmic: R = 0.716 vs. linear: R = 0.811; p < .001) (POF: logarithmic: R = 0.644 vs. linear: R = 0.548; p < .05). Thus, the results of this study revealed a constant correlation between RFA and conventional methods as a measurement validation, predicting favorable support for intraoperative PSF. RFA has the potential to be a new index for evaluating the implant fixation force.

Resonance frequency analysis with two different devices after conventional implant placement with ridge preservation: A prospective pilot cohort study

BACKGROUND

Primary and secondary implant stability is of high importance for survival and success of dental implants in the short and long term. Measurements of implant stability during healing provide the opportunity to monitor the course of the osseointegration process.

PURPOSE

To compare implant stability quotient (ISQ) by resonance frequency analysis (RFA), recorded with two different devices after implant placement.

MATERIALS AND METHODS

Patients with the need of single tooth extraction in posterior sites of the maxilla and the mandible were treated in a surgical center. All patients received additional augmentation with a bovine bone substitute and platelet-rich fibrin (PRF) after atraumatic tooth extraction. After a healing period of 10 weeks, 28 self-tapping titanium-implants were placed. Implant stability was recorded with two different devices (Osstell and Penguin) at the time of implant insertion (T0), 10 days later (T1), and after 7 (T2), or 17 weeks (T3).

RESULTS

No implant was lost, and no postoperative complication occurred during follow-up. Patient cohort comprised 9 female (32.1%) and 19 male patients (67.9%), with a mean age of 52.8 years, 64.3 years, respectively. Mean overall insertion torque was 43.6 Ncm at implant placement with no significant difference between implant location, age, or gender. No patient dropped out. During observation period, a significant increase in mean ISQ was recorded with both devices. Significant positive correlations between insertion torque and ISQ were recorded with both devices at T0, T2, and T3. No significant differences were observed in ISQ-values between both devices, and measuring directions at any point of measurement.

CONCLUSIONS

Within the limitations of this cohort study, both devices were suitable for RFA-measurement and revealed comparable results. Due to the cordless design, handling of the Penquin device was more comfortable. Reusability of the Penguin MultiPeg-transducers may offer an additional benefit with regard on ecological aspects.

Is It Possible to Monitor Implant Stability on a Prosthetic Abutment? An In Vitro Resonance Frequency Analysis

In order to apply the “one-abutment–one-time” concept, we evaluated the possibility of measuring resonance frequency analysis (RFA) on the abutment. This trial aimed to compare the Implant Stability Quotient (ISQ) values obtained by the Penguin^RFA when screwing the transducer onto the implant or onto abutments with different heights and angulations. Eighty implants (VEGA^®, Klockner Implant System, SOADCO, Les Escaldes, Andorra) were inserted into fresh bovine ribs. The groups were composed of 20 implants, 12 mm in length, with two diameters (3.5 and 4 mm). Five different abutments for screwed retained restorations (Permanent^®) were placed as follows: straight with 1, 2, and 3 mm heights, and angulated at 18° with 2 and 3 mm heights. The mean value of the ISQ measured directly on the implant was 75.72 ± 4.37. The mean value of the ISQ registered over straight abutments was 79.5 ± 8.50, 76.12 ± 6.63, and 71.42 ± 6.86 for 1, 2, and 3 mm height abutments. The mean ISQ over angled abutments of 2 and 3 mm heights were 68.74 ± 4.68 and 64.51 ± 4.53 respectively. The present study demonstrates that, when the ISQ is registered over the straight abutments of 2 and 3 mm heights, the values decrease, and values are lower for angled, 3 mm height abutments.

Kriging Surrogate Model for Resonance Frequency Analysis of Dental Implants by a Latin Hypercube-Based Finite Element Method

The dental implantation in clinical operations often encounters difficulties and challenges of failure in osseointegration, bone formulation, and remodeling. The resonance frequency (RF) can effectively describe the stability of the implant in physical experiments or numerical simulations. However, the exact relationship between the design variables of dental implants and RF of the system is correlated, complicated, and dependent. In this study, an appropriate mathematical model is proposed to evaluate and predict the implant stability and performance. The model has merits not only in the prediction reliability and accuracy but also in the compatibility and flexibility, in both experimental data and numerical simulation results. The Kriging surrogate model is proposed to present the numerical relationship between RF and material parameters of dental implants. The Latin Hypercube (LH) sampling method as a competent and sophisticated method is applied and combined with the finite element method (FEM). The methods developed in this paper provide helpful guidance for designers and researchers in the implantation design and surgical plans.

A study on the use of the Osstell apparatus to evaluate pedicle screw stability: An in-vitro study using micro-CT

Pull-out force and insertion torque have not been generally used as intraoperative measures for the evaluation of pedicle screw stability because of their invasiveness. On the other hand, resonance frequency analysis is a non-invasive and repeatable technique that has been clinically used in dentistry to evaluate implant stability e.g. by the Osstell apparatus. In this study, the characteristics of the implant stability quotient (ISQ) value obtained by the Osstell apparatus in the field of spinal surgery were investigated. Biomechanical test materials simulating human bone were used to provide a comparative platform for evaluating each fixation strength measure, including pull-out force, insertion torque, and the ISQ value. To perform pull-out force measurement and to repeat pedicle screw insertion and removal, loosening was artificially created, and its effect was investigated. The grade of loosening was quantified on a micro-CT image after pedicle screw removal. In the comparison of the 3 fixation strength measures, the correlations of the ISQ value with the pull-out force (R² = 0.339 p <0.0001) and the insertion torque (R² = 0.337 p <0.0001) were lower than the correlation between pull-out force and insertion torque (R² = 0.918 p <0.0001). On a micro-CT study, the material volume of the internal threads disappeared after destruction of its integrity due to repeated pedicle screw insertion and removal. Material integrity destruction of the internal threads decreased only the pull-out force and the insertion torque, but it did not affect the ISQ value. The ISQ value only decreased when the material volume of the internal threads disappeared, probably because the ISQ value reflects the resistance against a force in the perpendicular direction of the screw, unlike the conventional measures of fixation strength, such as pull-out force and insertion torque, which reflect axial load.

Effect of location on primary stability and healing of dental implants

PURPOSE

To study implant primary stability and bone healing using resonance frequency analysis in different anatomical locations 4 months after placement.

MATERIAL AND METHODS

Fifty-six partially edentulous patients restored by dental implants were included. Overall, 214 implants were placed without bone or soft tissue augmentation. All implants were placed with the same drilling protocol and implant insertion torque (35-40 N · cm).

RESULTS

The mean implant stability quotient (ISQ) value at baseline for all the locations was 75.4 mm (95% confidence interval, 74.20-76.59 mm). Higher ISQ values were found in the mandible. A significant difference between ISQ values of each location (P < 0.001) was identified. The mean values obtained showed an increase (3.4%) in all the locations, being greater in the posterior lower and upper maxillae (3.8%), whereas for the anterior maxilla, it was the least (1.5%) 4 months after healing. This increase was statistically significant in the posterior upper and lower maxillae (P < 0.001).

CONCLUSION

Higher implant stability was found in mandible compared with maxilla in both periods, immediately after insertion and 4 months later. Therefore, according to ISQ values, restoring implants immediately after insertion or after a healing period of 4 months represents safe time points.

Finite element simulation of ultrasonic wave propagation in a dental implant for biomechanical stability assessment

Dental implant stability, which is an important parameter for the surgical outcome, can now be assessed using quantitative ultrasound. However, the acoustical propagation in dental implants remains poorly understood. The objective of this numerical study was to understand the propagation phenomena of ultrasonic waves in cylindrically shaped prototype dental implants and to investigate the sensitivity of the ultrasonic response to the surrounding bone quantity and quality. The 10-MHz ultrasonic response of the implant was calculated using an axisymetric 3D finite element model, which was validated by comparison with results obtained experimentally and using a 2D finite difference numerical model. The results show that the implant ultrasonic response changes significantly when a liquid layer is located at the implant interface compared to the case of an interface fully bounded with bone tissue. A dedicated model based on experimental measurements was developed in order to account for the evolution of the bone biomechanical properties at the implant interface. The effect of a gradient of material properties on the implant ultrasonic response is determined. Based on the reproducibility of the measurement, the results indicate that the device should be sensitive to the effects of a healing duration of less than one week. In all cases, the amplitude of the implant response is shown to decrease when the dental implant primary and secondary stability increase, which is consistent with the experimental results. This study paves the way for the development of a quantitative ultrasound method to evaluate dental implant stability.

The effects of implant angulation on the resonance frequency of a dental implant

Dental implants are ideally placed in an orientation that allows vertical transfer of occlusal forces along their long axis. Nevertheless, optimal situations for implant placement are seldom encountered resulting in implants placement in angulated positions, which may affect their long-term success. The resonance frequency (RF) is an objective tool used to monitor stability of the implant tissue integration; however, little is known of the effect of the implant orientation in bone on the RF and its potential significance. The purpose of this research was to determine the relation between the dental implant orientation and the corresponding RF of implant. Three-dimensional (3D) modelling software was used to construct a 3D model of a pig mandible from computed tomography (CT) images. The RF of the implant was analysed using finite element (FE) modal analysis in software ANSYS (v.12). In addition, a cubical model was also developed in MIMICS to investigate the parameters affecting the relationship between RF and implant orientation in a simplified environment. The orientation angle was increased from 0 to 10 degrees in 1 degree increments and the resulting RF was analysed using correlation analysis and one-way ANOVA. Our analysis illustrated that the RF fluctuation following altering implant orientation was strongly correlated (r=0.97) with the contacting cortical to cancellous bone ratio (CCBR) at the implant interface. The most extreme RF change (from 9.81kHz to 10.07kHz) occurred when the implant was moved 0.5mm in positive z-direction, which resulted in the maximum change of CCBR from 52.9 to 54.8.

An ex vivo model in human femoral heads for histopathological study and resonance frequency analysis of dental implant primary stability

OBJECTIVE

This study was designed to explore relationships of resonance frequency analysis (RFA)-assessed implant stability (ISQ values) with bone morphometric parameters and bone quality in an ex vivo model of dental implants placed in human femoral heads and to evaluate the usefulness of this model for dental implant studies.

MATERIAL AND METHODS

This ex vivo study included femoral heads from 17 patients undergoing surgery for femoral neck fracture due to osteoporosis (OP) (n = 7) or for total prosthesis joint replacement due to severe hip osteoarthrosis (OA) (n = 10). Sixty 4.5 × 13 mm Dentsply Astra implants were placed, followed by RFA. CD44 immunohistochemical analysis for osteocytes was also carried out.

RESULTS

As expected, the analysis yielded significant effects of femoral head type (OA versus OA) (P < 0.001), but not of the implants (P = 0.455) or of the interaction of the two factors (P = 0.848). Bonferroni post hoc comparisons showed a lower mean ISQ for implants in decalcified (50.33 ± 2.92) heads than in fresh (66.93 ± 1.10) or fixated (70.77 ± 1.32) heads (both P < 0.001). The ISQ score (fresh) was significantly higher for those in OA (73.52 ± 1.92) versus OP (67.13 ± 1.09) heads. However, mixed linear analysis showed no significant association between ISQ scores and morphologic or histomorphometric results (P > 0.5 in all cases), and no significant differences in ISQ values were found as a function of the length or area of the cortical layer (both P > 0.08).

CONCLUSION

Although RFA-determined ISQ values are not correlated with morphometric parameters, they can discriminate bone quality (OP versus OA). This ex vivo model is useful for dental implant studies.

Comparison of implant primary stability between maxillary edentulous ridges receiving intramembranous origin block grafts

Purpose: The purposes of the present study were: to compare the resonance frequency analysis (RFA) values of implant placed in either ramus or calvaria block grafts; and to determine if implant diameter influences RFA implant stability quotient (ISQ) value. Material and Methods: This was a retrospective study that included 16 consecutives healthy patients treated with autogenous onlay block grafts for horizontal bone reconstruction in maxilla. Ten ramus and ten calvaria block graft treated patients were selected and compared. Results: Totally, 59 implants were placed, 35 (59.3%) were placed on the calvaria bone grafts and the remaining 24 (40.7%) were on the ramus bone graft. Of all the implants studied, 13 (22%), 35 (59.3%), and 11 (18.6%) were 10 mm, 11.5 mm and 13 mm in length respectively. Regarding the diameter, 4 (7%) were 3.3 mm, 3 (5%) were 3.5 mm, 20 (34%) were 3.7 mm and 32 (54%) were 4 mm. Mean ISQ value obtained by RFA was 73.06 ± 6.08, being 72.19 ± 6 and 74.47 ± 6.06 for the calvaria and ramus treated group respectively. No significant differences were noted between the two groups (p= 0.154). Implants were pooled and divided by their diameter. Mean ISQ value obtained for 3.3 mm was 80 ± 5.09, while for 4.0 mm was 72.5 ± 7.19. Again, no significant differences were found among the groups (p= 0.138). Conclusion: For RFA ISQ value, the bone graft origins (calvaria or ramus) or implant diameters did not influence the outcome.

Key words:Bone augmentation, dental implant, resonance frequency analysis, implant stability.