Initial Stability Measurements of Implants Using a New Magnetic Resonance Frequency Analyzer With Titanium Transducers: An Ex Vivo Study

Acoustic resonance frequency analysis for evaluating prosthetic screw stability in splinted implant-supported fixed dental prostheses: An in vitro study

STATEMENT OF PROBLEM

Prosthetic screw loosening is a common mechanical complication of implant-supported fixed dental prostheses. Although techniques for detecting screw loosening in single implant-supported fixed dental prostheses have been reported, studies on the screw stability for splinted implant-supported fixed dental prostheses are lacking.

PURPOSE

The purpose of this in vitro study was to determine whether acoustic resonance frequency analysis using a newly developed system could detect prosthetic screw loosening in splinted implant-supported fixed dental prostheses.

MATERIAL AND METHODS

Maxillary and mandibular edentulous gypsum casts with screw-retained definitive fixed dental prostheses supported by 6 implants were used. A tapping simulation (0.2 N, 50 Hz) was directly applied to the buccal side of the tested screw, and a pickup device was used to collect the acoustic signals. The resonance peak frequencies of these signals were extracted by using time-frequency-domain analysis based on short-time Fourier transform. A 2-way mixed analysis of variance was performed to evaluate how jaw position and insertion torque affect resonance peak frequency. The Pearson correlation analysis was used to assess the relationship between the insertion torque and resonance peak frequency for each screw (α=.05).

RESULTS

Deviation from the insertion torque resulted in significant changes in the resonance peak frequency within 6 to 9 kHz. Additionally, significant positive correlation between the insertion torques and resonance peak frequencies was observed for all screws (P<.05). This correlation was affected by the position of the screw within the prosthesis. Specifically, screw loosening in the posterior and anterior regions had a greater influence on the resonance peak frequency than that in the central region.

CONCLUSIONS

The acoustic resonance peak frequency shifted leftward as the screw preload torque decreased, indicating a significant correlation with screw stability. These results suggest that acoustic resonance frequency analysis can be used to detect the stability status of a single prosthetic screw in a splinted implant-supported fixed dental prosthesis conveniently and with high sensitivity.

Resonance frequency analysis of dental implants in patients with vitamin D deficiency

OBJECTIVES

Vitamin D deficiency may influence dental implant osseointegration unfavourably. The aim of this study was to compare dental implant stabilities of patients with different levels of vitamin D and investigate the effects of vitamin D supplementation.

MATERIALS AND METHODS

One hundred and twenty-nine patients who underwent dental implantation were grouped regarding vitamin D levels and supplement use: Group A; vitamin D deficiency and supplement usage, Group B; insufficiency with supplement usage, Group C; insufficiency without supplements and Group D; vitamin D sufficiency. Resonance frequency analysis (RFA) measurements were performed at baseline and 3 months. Patients with vitamin D deficiency (Group A) and insufficiency (Group B) were prescribed supplements by specialists. Pearson correlation analysis was used to examine an association between vitamin D levels and implant stability.

RESULTS

Primary stability of Group D (76.34 ± 6.55) was significantly higher than Groups A, B and C at baseline (p < 0.05). At 3 months, Group C scored significantly lower than the other groups (p < 0.05). The results revealed a correlation between serum levels of vitamin D and RFA measurements at 3 months (p < 0.05).

CONCLUSION

It was observed that high vitamin D levels influenced implant stabilities positively, as evidenced by higher Implant Stability Quotient values. Low levels of vitamin D may be associated with a decrease in implant stability.

STATEMENT OF CLINICAL RELEVANCE

Vitamin D, concerning its impact on bone metabolism, is currently of particular interest in implant dentistry. The lower stability scores in patients with vitamin D deficiency reinforce the recommendation of Vitamin D supplementation when treating those patients with dental implants.

Correlation Between Implant Stability Quotient and Percussion Sound Frequency

OBJECTIVES

To determine the correlation between the primary implant stability quotient and the implant percussion sound frequency.

MATERIALS AND METHODS

A total of 14 pigs' ribs were scanned using a dental cone beam computed tomography (CBCT) scanner to classify the bone specimens into three distinct bone density Hounsfield units (HU) value categories: D1 bone: >1250 HU; D2: 850-1250 HU; D3: <850 HU. Then, 96 implants were inserted: 32 implants in D1 bone, 32 implants in D2 bone, and 32 implants in D3 bone. The primary implant stability quotient (ISQ) was analyzed, and percussion sound was recorded using a wireless microphone connected and analyzed with frequency analysis software.

RESULTS

Statistically significant positive correlations were found between the primary ISQ and the bone density HU value (r = 0.719; p < 0.001), and statistically significant positive correlations between the primary ISQ and the percussion sound frequency (r = 0.606; p < 0.001). Furthermore, significant differences in primary ISQ values and percussion sound frequency were found between D1 and D2 bone, as well as between D1 and D3 bone. However, no significant differences were found in primary ISQ values and percussion sound frequency between D2 and D3 bone.

CONCLUSION

The primary ISQ value and the percussion sound frequency are positively correlated.

Influence of Multiple Sterilization on Performance of Titanium Pegs When Measuring Implant Stability With Resonance Frequency Analyses

This in vitro study was conducted to investigate the repeatability of the implant stability quotients (ISQ) measured with multipegs after numerous sterilizations and to detect the exact time when the readings start to deviate. Multipegs were sterilized with 3 different methods (autoclaved, autoclaved + ultrasonic cleaner, chemical disinfection + autoclaved) and grouped according to the method applied. All specimens were put into the autoclave with sealed packages every time they were sterilized. Each specimen was sterilized 50 times according to the technique described in its group after an ISQ measurement was performed. Results of the 2-way analysis of variance showed that neither the sterilization method nor the cycles, nor their interaction, were statistically significant. A multipeg may be reused multiple times after sterilization procedures and may be more cost-effective than a disposable smartpeg for checking implant stability after confirming these results in further investigations.

A mathematical approach to estimate micro-displacement of a dental implant using electromagnetic Frequency Response Analysis

The aim of this paper is to formulate a mathematical model of dental prosthetic using single degree of freedom (SDOF) to assess the micro-displacement under electromagnetic excitation. Using Finite Element Analysis (FEA) and values from literature, stiffness and damping values of the mathematical model were estimated. For ensuring the successful implantation of dental implant system, monitoring of primary stability in terms of micro-displacement is crucial. One of the most popular techniques for the measurement of stability is the Frequency Response Analysis (FRA). This technique assesses the resonant frequency of vibration corresponding to the maximum micro-displacement (micro-mobility) of the implant. Among the different FRA techniques, the most common method is the Electromagnetic FRA. The subsequent displacement of the implant in the bone is estimated by equations of vibration. A comparison has been made to observe the variation in resonance frequency and micro-displacement due to varying input frequency ranges of 1-40 Hz. The micro-displacement and corresponding resonance frequency were plotted using MATLAB and the variation in resonance frequency is found to be negligible. The present mathematical model is a preliminary approach to understand the variation of micro-displacement with reference to electromagnetic excitation force and to obtain the resonance frequency. The present study validated the use of input frequency ranges (1-30 Hz) with negligible variation in micro-displacement and corresponding resonance frequency. However, input frequency ranges beyond 31-40 Hz is not recommended due to large variation in micromotion and corresponding resonance frequency.

In vivo osseointegration evaluation of implants coated with nanostructured hydroxyapatite in low density bone

OBJECTIVE

This in vivo study, aimed to biomechanically, histomorphometrically and histologically evaluate an implant surface coated with nanostructured hydroxyapatite using the wet chemical process (biomimetic deposition of calcium phosphate coating) when compared to a dual acid-etching surface.

MATERIAL AND METHODS

Ten sheep (2-4 years old) received 20 implants, 10 with nanostructured hydroxyapatite coating (HAnano), and 10 with dual acid-etching surface (DAA). The surfaces were characterized with scanning electron microscopy and energy dispersive spectroscopy; insertion torque values and resonance frequency analysis were measured to evaluate the primary stability of the implants. Bone-implant contact (BIC) and bone area fraction occupancy (BAFo) were evaluated 14 and 28 days after implant installation.

RESULTS

The HAnano and DAA groups showed no significant difference in insertion torque and resonance frequency analysis. The BIC and BAFo values increased significantly (p<0.05) over the experimental periods in both groups. This event was also observed in BIC value of HAnano group. The HAnano surface showed superior results compared to DAA after 28 days (BAFo, p = 0.007; BIC, p = 0.01).

CONCLUSION

The results suggest that the HAnano surface favors bone formation when compared to the DAA surface after 28 days in low-density bone in sheep.

Intra- and inter-operator concordance of the resonance frequency analysis. A cross-sectional and prospective clinical study

OBJECTIVE

Resonance frequency analysis (RFA) provides an evaluation of implant stability over time. This analysis is a non-invasive, precise, and objective method. Several studies compare the RFA system with other devices. However, few investigations analyze repeatability and reproducibility between different operators. The aim of this study was to evaluate the intra- and inter-operator concordance of the Osstell® ISQ.

MATERIAL AND METHODS

RFA measurements were performed with Osstell® ISQ in a total of 37 implants placed in 21 patients. At the time of implant placement, 6 measurements per implant were taken by three different experienced operators. Three measurements were carried out consecutively and three by removing and placing the SmartPeg-Osstell® to assess intra-operator and inter-operator agreement.

RESULTS

Intra-operator concordance according to the intraclass correlation coefficient (ICC) showed high concordance. The ICC values were higher than 0.9 (p < 0.0001) for consecutive measures and alternative measures, being almost perfect of Landis & Koch classification. For inter-operator concordance The ICC was 0.709 (p < 0.0001) and 0.670 (p < 0.0001) for consecutive and alternative measures, respectively, both estimates being in the substantial category. In torque and ISQ values, no statistically significant differences were observed when operators and measurements were compared.

CONCLUSIONS

Osstell® ISQ system was stable both in intra-operator and inter-operator measurements. This device has excellent repeatability and reproducibility, demonstrating reliability to measure the stability of dental implants.

CLINICAL RELEVANCE

Resonance frequency analysis (RFA) is a non-invasive, objective, and reliable diagnostic method to determine the ideal moment to load the implant, as well as to predict possible failures.

Evolution of anodised titanium for implant applications

Anodised titanium has a long history as a coating structure for implants due to its bioactive and ossified surface, which promotes rapid bone integration. In response to the growing literature on anodised titanium, this article is the first to revisit the evolution of anodised titanium as an implant coating. The review reports the process and mechanisms for the engineering of distinctive anodised titanium structures, the significant factors influencing the mechanisms of its formation, bioactivity, as well as recent pre- and post-surface treatments proposed to improve the performance of anodised titanium. The review then broadens the discussion to include future functional trends of anodised titanium, ranging from the provision of higher surface energy interactions in the design of biocomposite coatings (template stencil interface for mechanical interlock) to techniques for measuring the bone-to-implant contact (BIC), each with their own challenges. Overall, this paper provides up-to-date information on the impacts of the structure and function of anodised titanium as an implant coating in vitro and in/ex vivo tests, as well as the four key future challenges that are important for its clinical translations, namely (i) techniques to enhance the mechanical stability and (ii) testing techniques to measure the mechanical stability of anodised titanium, (iii) real-time/in-situ detection methods for surface reactions, and (iv) cost-effectiveness for anodised titanium and its safety as a bone implant coating.

Comparison of reliability of three resonance frequency analysis devices: An in vitro study

The purpose of the present study was to investigate the intra-observer and inter-observer reliability of three resonance frequency analysis (RFA) devices and to compare the implant stability quotient (ISQ) values according to implant macro design and diameter in two different bone densities. A total of 64 implants (Neoss Proactive) of varying diameters (3.5 and 4.0 mm) and implant macro design (tapered and straight) were placed in two artificial bone blocks (the density of type 2 and 3). The implant primary stability was measured using Osstell IDx, Osstell Beacon and Penguin RFA. The ISQ value of each implant was measured by two observers and recorded five times in two directions. The intra-observer and inter-observer reliability of RFA devices were evaluated. In addition to that, mean ISQ values were calculated for each RFA device to evaluate the effect of implant diameter, implant macro design, and bone density on ISQ values. ISQ values were significantly higher for implants placed within the type 2 bone than for the type 3 bone. The 4.0 mm diameter implants presented higher ISQ values than 3.5 mm diameter implants. The intra-class correlation coefficient (ICC) values for intra-observer reliability were above 0.85 for each observer and the ICC values for inter-observer reliability were 0.94, 0.93, 0.98 for Osstell IDx, Osstell Beacon and Penguin RFA, respectively. Although there was excellent inter-observer reliability with three RFA devices, the intra-observer reliability of Osstell Beacon and Penguin RFA were slightly better than Osstell IDx. Bone density and implant diameter were parameters affecting the primary stability of implants.

The Influence of Nanostructured Hydroxyapatite Surface in the Early Stages of Osseointegration: A Multiparameter Animal Study in Low-Density Bone

Background and Objective

The success rates of dental implants in low-density bone have been reported as a challenge, especially for early or immediate loading in the maxilla posterior area. Nanoscale architecture affects the roughness, surface area, surface energy of the implant and can enhance osseointegration. This study aimed to evaluate the implant-surface topography and biomechanical, histomorphometric, and histological bone responses to a new nanostructured hydroxyapatite surface placed in the iliac crest of sheep.

Methods

Ten female sheep (2–4 years) received 30 implants (n=10/group): HAnano^® coated (Epikut Plus^®, S.I.N. Implant System, Sao Paulo, SP, Brazil), SLActive (BLX^®, Straumann, Basel, Switzerland), and TiUnite (NobelActive^®, Nobel Biocare, Göteborg, Sweden) surfaces. Scanning electron microscopy with energy-dispersive spectroscopy evaluated the implant surface topography, the insertion torque value, and resonance frequency analysis evaluated the primary stability, bone-implant contact, and bone-area fraction occupancy were evaluated after 14 and 28 days after implant placement.

Results

The surface morphology was considerably comparable between the implant groups’; however, the TiUnite^® group presented a remarkable different surface. The SLActive^® and TiUnite^® groups presented an insertion torque average of 74 (±8.9) N/cm that was similar to that of HAnano^® 72 (±8.3) N/cm (p >0.05). The resonance frequency evaluated with Osstell^®/SmartPeg^® or Penguin^®/MulTipeg^® showed similar results when assessing implants from the same group. BIC and BAFO significantly increased (p<0.05) throughout the experimental periods to all groups, but BIC and BAFO values were similar among the implants at the same time point. After 4 weeks, bone-implant contact was higher than 80% of the total length analyzed. New bone occupies around 60% of analyzed area around the implants.

Conclusion

HAnano^® coated surface promoted comparable osseointegration as SLActive and TiUnite in the sheep model. The three tested surfaces showed comparable osseointegration at the early stages of low-density bone repair in the sheep model.