Resonance frequency analysis of one-stage dental implant stability during the osseointegration period

Evaluation of safety and efficacy of locally developed dental implants: A noninferiority randomized controlled trial

STATEMENT OF PROBLEM

Various dental implants are available in India, but imported devices are expensive; an affordable locally produced dental implant system would be beneficial.

PURPOSE

The purpose of this noninferiority randomized controlled trial was to compare the safety and efficacy of a locally developed dental implant system to those of an established imported dental implant system with similar microsurface characteristics.

MATERIAL AND METHODS

A total of 136 participants with 201 partially edentulous sites, aged 18 to 65 years, were enrolled in the trial, with 134 sites receiving test implants and 67 sites control implants (n ratio, 2:1). The implants received a delayed submerged healing protocol and were loaded 3 to 6 months after surgery. Maximum insertion torque (IT) was recorded during the implant surgery, and the implant stability quotient (ISQ) was evaluated on the day of surgery and at the second-stage procedure. The mean crestal bone loss (MCBL) was measured on periapical radiographs at prosthetic placement (baseline) and at 6 months and 12 months after loading. The primary measure of outcome was the implant survival rate, and the secondary measure of evaluation was the intergroup difference in MCBL at baseline, 6 months, and 12 months.

RESULTS

A total of 127 test and 61 control implant sites were available for follow-up 1 year after prosthesis placement. At the end of 12 months, the test and control implant groups demonstrated a survival rate of 97% and 100%, respectively. The MCBL difference was significant between the 2 groups at baseline (P<.05). However, at 6 and 12 months, the difference between the test and control groups was not significantly different (P>.05).

CONCLUSIONS

The survival rate of the test group fell within the previously assumed 10% noninferiority margin. Therefore, the null hypothesis was accepted for the trial, and the locally developed implants were noninferior to the imported implants at a sample allocation ratio of 2:1.

Evaluation of different surface treated implants after provisionalization: A 6-month prospective study

Background

Replacing missing teeth with dental implants has become the best treatment option; therefore, clinicians need to understand the predictability of the treatment. Surface treatment of implants is one of the methods to improve osseointegration, thus improving the quality of treatment. Increasing esthetic awareness among patients has led to the popularity of immediate provisionalization of dental implants. This study investigated the effect of surface treatment on implant stability when loaded with immediate non-functional temporary prostheses and compared the superiority of one surface treatment over the other in terms of osseointegration by evaluating implant stability quotient (ISQ).

Methods

Twenty implants with different surface treatments were placed, i.e., resorbable blast media (RBM) surface and alumina blasted/acid-etched (AB/AE) surfaces. All the implants were non-functionally loaded, and ISQ was measured immediately after implant placement and 6 and 12 weeks after non-functional loading. Crestal bone levels, mPI, mSBI, and peri-implant probing depths were compared for both groups at 1, 3, and 6 months.

Results

At 12 weeks, all the implants showed desirable ISQ, indicating successful osseointegration. The increase in ISQ at 12 weeks was significantly higher for RBM implants compared to baseline, indicating a more predictable course of osseointegration. Crestal bone levels recorded at 1, 3, and 6 months did not significantly differ between the groups. All other parameters showed comparable values for both groups at all intervals.

Conclusion

Replacing missing teeth with dental implants with immediate non-functional restorations is a predictable treatment option.

Crestal sinus augmentation in a head back position: Retrospective case series

Objectives

To evaluate the clinical efficacy of Crestal Sinus Augmentation (CSA) in a head back position (CSA-HBP) for maxillary sinus mucosa elevation.

Materials and Methods

We enrolled 209 patients, 246 maxillary sinuses, 348 sites in this study. Complications, maxillary sinus mucosal perforation rate and cumulative survival rate (CSR) data were collected to evaluate the clinical efficacy of CSA-HBP. Maxillary sinus mucosal elevation height (EH) and new bone height (NH) were measured by cone-beam computerized tomography and standard periapical radiographs. The implantation sites of residual bone height (RBH) ≤5 mm and RBH >5 mm were marked as Groups A (n = 81) and B (n = 267), respectively. The implantation sites of the second and third molar sites were marked as Group C (n = 134), and the remaining sites were marked as Group D (n = 214).

Results

The RBH before implant placement was 6.63 ± 2.10 mm (95% confidence interval [CI] 6.41- 6.85 mm). The mucosal EH was 4.04 ± 1.86 mm (95% CI 3.85 - 4.24 mm). The NH was 2.36 ± 1.20 mm (95% CI 3.85-4.24 mm). No other complications were found except three cases of postoperative swelling and one case of nasal blood secretions. The overall mucosal perforation rate was 1.44% (5/348, 95% CI 0.2%-2.7%) and the rate of RBH ≤ 5 mm (Group A) was 1.49% (2/134, 95% CI 0%-3.50%). The 8-year CSR was 99.71% (347/348, 95% CI 99.2%-100.0%). Mucosal EH and NH were higher in RBH ≤5 mm (Group A) than in RBH >5 mm (Group B) (P = 0.001 and P = 0.001, Mann-Whitney U-test). There were no significant differences in mucosal EH and perforation rate between second and third molar sites (Group C) and other sites (Group D) (P = 0.77, Mann-Whitney U-test, and P = 0.16, Yates' Chi-square independence test).

Conclusions

CSA-HBP is a minimally invasive and reliable technique.

Surface Modifications of Commercial Dental Implant Systems: An Overview

The aim of this review was to perform a comprehensive overview of evidence pertaining to the influence of various surface modifications on the surface roughness, bone implant contact, and the success and complication rates of the implants. Modified sandblasted, large-grit, acid-etched (SLA) implants (SLActive implants) have a higher implant stability quotient compared with conventional SLA implants. Also, when compared between the implant surfaces from various manufacturers, Biomet 3i Nanotite implants were shown to have a relatively higher implant stability quotient compared to Straumann implants as well as the Biomet Osseotite implants. Only one study reports the insertion torque values as obtained by the various implant surfaces, with the findings being statistically similar for all the types, and a higher mean value for Biomet 3i Nanotite implants. Among SLA and SLActive surfaces, the latter was found to have a lower marginal bone loss, and among Astratech implants, the marginal bone loss levels were similar for Osseospeed and Tioblast surfaces. When Osseospeed, TiUnite and SLActive surfaces were compared, Osseospeed was found to have the minimum bone loss while TiUnite was found to have the highest. The bone implant contact percentages are similar and satisfactory for most of the implant surface modifications that are available currently. Upon assessing the recent literature on the survival rates for implants with various surface modifications, it was found that among Nobel Biocare implants, the survival rate was higher for TiUnite implants, compared with the turned surfaces. Surprisingly, among the Straumann implant surfaces, the survival rates were found to be higher for the SLA implants when compared to the modified SLA implants. Only one of the included studies evaluated the survival rate for Astratech implant surfaces and found a 100% survival rate for both the Osseospeed and Tioblast surface implants. Therefore, major advancements have been made in developing novel surfaces of dental implants. The numerous innovations set the stage for rehabilitating patients with high success and predictable survival rates even in challenging conditions.

Modelling the resonant frequency associated with the spatio-temporal evolution of the bone-dental implant interface

Dental implant stability is greatly affected by the mechanical properties of the bone-implant interface (BII), and it is key to long-term successful osseointegration. Implant stability is often evaluated using the Resonant Frequency Analysis (RFA) method, and also by the quality of this interface, namely the bone-implant contact (BIC). True to this day, there is a scarcity of models tying BIC, RFA and a spatially and mechanically evolving BII. In this paper, based on the contact/distance osteogenesis concept, a novel numerical spatio-temporal model of the implant, surrounding bone and evolving interface, was developed to assess the evolution of the interfacial stresses on the one hand and the corresponding resonant frequencies on the other. We postulate that, since the BIC percentage reaches saturation over a very short time, long before densification of the interface, it becomes irrelevant as to load transmission between the implant and the bone due to the existence of an open gap. Gap closure is the factor that provides continuity between the implant and the surrounding bone. The results of the calculated RFA evolution match and provide an explanation for the multiple clinical observations of a sharp initial decline in RFA, followed by a gradual increase and plateau formation. STATEMENT OF SIGNIFICANCE: A novel three-dimensional numerical model of an evolving bone-dental implant interface (BII) is presented. The spatio-temporal evolution of the bone-implant contact (BIC) and the BII, based on contact/distance (CO/DO) osteogenesis, is modeled. A central outcome is that, until BII maturation into a solid continuous bone (no open gap between CO-DO fronts), the bone-implant load transfer is hampered, irrespective of the BIC. The resonant frequencies' evolution of the jawbone-BII-implant is calculated to reproduce the well-established implant stability analysis based on the Resonant Frequency Analysis. The results resemble those reported clinically, and here too, the determinant transition occurs only after interfacial gap closure. Those results should motivate clinicians to re-consider structural continuity of the BII rather than the BIC only.

Fixture Length and Primary Stability: An In Vitro Study on Polyurethane Foam

(1) Background: Recently, novel dental implants that are characterized by different levels of surface roughness in the distinct parts of the fixture’s body have been introduced in the market. These surface characteristics could affect the primary stability of the implants. The aim of this in vitro study was to compare the primary stability of short and long implants, characterized by multiscale surface roughness, inserted on polyurethane blocks. The secondary aim was to understand if the implant length could be a crucial factor in the decision-making in immediate or rather than delayed loading protocol in the different bone densities. (2) Methods: A total of 20 cylindrical dental implants with a diameter of 5.0 mm were tested for the lengths 6.0 mm (short implants) versus 13.0 mm (long implants) on two different solid rigid polyurethane blocks (20 and 30 PCF). The primary stability was evaluated by measuring the insertion torque value (ITV), the removal torque (RTV), and the resonance frequency analysis RFA. (3) Results: The values of ITV, RTV, and RFA showed the same trend in all measurements. Long implants showed a significantly higher primary stability on 30 PCF blocks that present mechanical properties similar to high-density bone. On the contrary, no relevant differences were found on 20 PCF blocks, which mimic trabecular bone density. (4) Conclusions: The impact of fixture length on the primary stability of implants with multiscale surface roughness is significant in 30 PCF polyurethane corresponding to higher bone density, but not in lower ones.

Assessment of dental implant stability using resonance frequency analysis and quantitative ultrasound methods

Purpose Quantitative ultrasound (QUS) and resonance frequency analyses (RFA) are promising methods to assess the stability of dental implants. The aim of this in vivo preclinical study is to compare the results obtained with these two techniques with the bone-implant contact (BIC) ratio, which is the gold standard to assess dental implant stability.Methods Twenty-two identical dental implants were inserted in the tibia and femur of 12 rabbits, which were sacrificed after different healing durations (0, 4, 8 and 13 weeks). For each implant, the ultrasonic indicator (UI) and the implant stability quotient (ISQ) were retrieved just before the animal sacrifice using the QUS and RFA techniques, respectively. Histomorphometric analyses were carried out to estimate the bone-implant contact ratio.Results UI values were found to be better correlated to BIC values (R²=0.47) compared to ISQ values (R²=0.39 for measurements in one direction and R²=0.18 for the other direction), which were shown to be dependent on the direction of measurements. Errors realized on the UI were around 3.3 times lower to the ones realized on the ISQ.Conclusions QUS provide a better estimation of dental implant stability compared to RFA. This study paves the way for the future clinical development of a medical device aiming at assessing dental implant stability in a patient-specific manner. Clinical studies should confirm these results in the future.

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.

How Do Parameters of Implant Primary Stability Correspond with CT-Evaluated Bone Quality in the Posterior Maxilla? A Correlation Analysis

The aim of the present study was to evaluate correlations between bone density and implant primary stability, considering various determinants such as age, gender, and geometry of implants (design, diameter). Bone density of edentulous posterior maxillae was assessed by computed tomography (CT)-derived Hounsfield units, and implant primary stability values were measured with insertion torque and resonance frequency analysis (RFA). A total of 60 implants in 30 partially edentulous patients were evaluated in the posterior maxilla with two different types of dental implants. The bone density evaluated by CT-derived Hounsfield units showed a significant correlation with primary stability parameters. The bone quality was more influenced by gender rather than age, and the type of implant was insignificant when determining primary stability. Such results imply that primary stability parameters can be used for objective assessment of bone quality, allowing surgical modifications especially in sites suspected of poor bone quality.

Factors Influencing Primary and Secondary Implant Stability—A Retrospective Cohort Study with 582 Implants in 272 Patients

The success rate of dental implants depends on primary and secondary stability. We investigate predictive factors for future risk stratification models. We retrospectively analyze 272 patients with a total of 582 implants. Implant stability is measured with resonance frequency analysis and evaluated based on the implant stability quotient (ISQ). A linear regression model with regression coefficients (reg. coeff.) and its 95% confidence interval (95% CI) is applied to assess predictive factors for implant stability. Implant diameter (reg. coeff.: 3.28; 95% CI: 1.89–4.66, p < 0.001), implant length (reg. coeff.: 0.67, 95% CI: 0.26–1.08, p < 0.001), and implant localization (maxillary vs. mandibular, reg. coeff.: −7.45, 95% CI: −8.70–(−6.20), p < 0.001) are significant prognostic factors for primary implant stability. An increase in ISQ between insertion and exposure is significantly correlated with healing time (reg. coeff.: 0.11, 95% CI: 0.04–0.19). Patients with maxillary implants have lower ISQ at insertion but show a higher increase in ISQ after insertion than patients with mandibular implants. We observe positive associations between primary implant stability and implant diameter, implant length, and localization (mandibular vs. maxillary). An increase in implant stability between insertion and exposure is significantly correlated with healing time and is higher for maxillary implants. These predictive factors should be further evaluated in prospective cohort studies to develop future preoperative risk-stratification models.

Reliability of the Resonance Frequency Analysis Values in New Prototype Transepithelial Abutments: A Prospective Clinical Study

Resonance frequency analysis (RFA) requires abutment disconnection to monitor implant stability. To overcome this limitation, an experimental transepithelial abutment was designed to allow a SmartPeg to be screwed onto it, in order to determine the prototype abutments repeatability and reproducibility using Osstell ISQ and to assess whether implant length and diameter have an influence on the reliability of these measurements. RFA was conducted with a SmartPeg screwed directly into the implant and onto experimental abutments of different heights of 2, 3.5 and 5 mm. A total of 32 patients (116 implants) were tested. RFA measurements were taken twice for each group from mesial, distal, buccal and palatal/lingual surfaces. Mean values and SD were calculated and Intraclass Correlation Coefficients (ICC) (p < 0.05, IC 95%). The implant stability quotient (ISQ) mean values were 72.581 measured directly to implant and 72.899 (2 mm), 72.391 (3.5 mm) and 71.458 (5 mm) measured from the prototypes. ICC between measurements made directly to implant and through 2-, 3.5- and 5-mm abutments were 0.908, 0.919 and 0.939, respectively. RFA values registered through the experimental transepithelial abutments achieved a high reliability. Neither the implant length nor the diameter had any influence on the measurements' reliability.

Implant stability and survival rates of a hydrophilic versus a conventional sandblasted, acid-etched implant surface: Systematic review and meta-analysis

BACKGROUND

Modifying the implant surface via enhancing the wettability (hydrophilicity) improves osseointegration, reducing the healing period. In this study, the authors aimed to evaluate the stability and survival rates of implants with a hydrophilic surface compared with those with a sandblasted, acid-etched surface.

TYPES OF STUDIES REVIEWED

The included studies (randomized controlled trials) were identified through searches of PubMed, ScienceDirect, and Cochrane Library databases without date of publication restrictions. Quality assessment was performed using the Cochrane Collaboration tool. For primary outcome, confidence intervals were set at 95%; weighted means across the studies were calculated using a fixed-effects model or risk ratios and their 95% confidence intervals for secondary outcome.

RESULTS

The authors included 5 randomized controlled trials (246 dental implants) in the systematic review, which compared a hydrophilic with conventional sandblasted, acid-etched implant surface. The implant stability (primary outcome) was measured at baseline and 3, 6, and 8 weeks, and implant survival rates were measured as a secondary outcome. Overall, compared with the control groups, no clinically significant differences in implant stability or survival rates were identified for the hydrophilic surface groups.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The results did not show any clinically significant effect of a hydrophilic surface on improving implant stability or survival rates. However, these findings must be analyzed carefully owing to the limitations of this review, such as the small samples size and some differences among the included studies.

Relationship between Implant Length and Implant Stability of Single-Implant Restorations: A 12-Month Follow-Up Clinical Study

Background and Objectives: Implant stability in vivo is contingent on multiple factors, such as bone structure, instrument positioning and implant surface modifications, implant diameter, and implant length. Resonance-frequency analysis is considered a non-invasive, reliable, predictable, and objective method by which to evaluate implant stability, due to its correlation with bone-to-implant contact. The purpose of this study was to evaluate the effect of implant length on the primary and secondary stability of single-implant crown rehabilitations, as measured by resonance-frequency analysis at different times. Materials and Methods: Implants of 10 and 11.5 mm were placed, and the resonance frequency was measured at the time of surgery (T0), as well as at 3 (T1), 6 (T2), and 12 (T3) months post-surgery. Results: A total of 559 implants were placed in 195 patients. Significant differences were observed when comparing the implant stability quotient (ISQ) values at T1, with values for 10-mm implants being greater than those for 11.5-mm implants (p = 0.035). These differences were also observed when comparing ISQ values for buccal and lingual areas. At T0, T2, and T3, no significant differences in ISQ values were observed. The use of 10-mm implants in the anterior maxilla yielded significantly greater values at T0 (p = 0.018) and T1 (p = 0.031) when compared with 11.5-mm implants. Significant differences in measurements were observed only for buccal areas (p = 0.005; p = 0.018). When comparing the sample lengths and sex, women with 11.5-mm implants showed significantly lower results than those with 10-mm implants (p < 0.001). Conclusions: There is a direct relationship between implants of a smaller length and greater ISQ values, with this relationship being most evident in the maxilla and in women.

Use of resonance frequency analysis to evaluate the effects of surface properties on the stability of different implants

OBJECTIVES

We performed a randomized clinical study evaluating the stability of implants with different surfaces (alkali-modified or sandblasted) via resonance frequency analysis (RFA).

MATERIALS AND METHODS

Fourteen patients who were bilaterally edentulous in terms of their mandibular molars were enrolled. Implants with alkali-modified (bioactive) and sandblasted surfaces were randomly placed in either hemi-arch; the 50 implants used were identical in terms of diameter and length. RFA was used to measure the implant stability quotient (ISQ) immediately after placement (to assess primary stability) and 2, 6, and 12 weeks later.

RESULTS

The average RFA value for alkali-modified implants was significantly higher than that for sandblasted implants immediately after implantation, but the ISQs fell rapidly and were similar in the two groups at 2 and 6 weeks (p > .05); ISQ values were the same in the two groups at 3 months (p > .05).

CONCLUSIONS

Implants with alkali-modified surfaces were more stable than implants with sandblasted surfaces at all times after placement. The ISQs of bioactive implants exhibiting high-level primary stability fell to greater extents than did those of implants with sandblasted surfaces at 2 and 6 weeks postoperatively; both types of implant yielded similar clinical results at 12 weeks postoperatively.

Porous Titanium Granules for Sinus Floor Augmentation: A Case Series Study

Background:

Sinus grafting with autogenous bone and other bone substitutes has been shown to be a safe technique with high predictability of success, but it has not been determined which of these materials provide better osteogenic potential. The aim of the present study was to clinically and radiographically evaluate the use of Natix™ grafting material in maxillary sinus elevation procedures with simultaneous implant placement in humans.

Materials and Methods:

Fifteen patients (6 women and 9 men) requiring augmentation of the maxillary sinus before implant placement were voluntarily enrolled in this study. After the sinus graft procedure, a bone augmentation material of porous titanium granules (Natix™, TigranTecnologies, Malmö, Sweden) was placed into the sinus cavity. The primary stability of the fixtures was measured at baseline and 6 months following the implantation. Panoramic x-rays for objective measurements of bone height at the floor of sinus were repeated at 18 months, and 36 months postoperatively.

Results:

The 15 patients had in total 20 implants installed. Panoramic radiographs made 6 months post-insertion showed a radio-opaque area around the implants.Also at 6 months post-placement, all 18 implants were clinically stable and abutments were connected. Bone biopsies were taken from 1 grafted site in 1 patient. Excluding the one implant failing to achieve primary stability at baseline, the cumulative implant survival rate in this pilot study was 94.7%.

Conclusion:

The results of the study showed that maxillary sinus augmentation with porous titanium granules provided predictable survival of implants in 36 months.

Evaluations of miniscrew type-dependent mechanical stability

BACKGROUND

Miniscrew has been widely used as an absolute anchorage in orthodontic treatment. Types of miniscrew with different diameter, length, shape, and thread dimensions may have a substantial effect on mechanical stability of the miniscrew system. Thus, the objective of this study was to evaluate miniscrew type-dependent mechanical stability to assess mechanical properties of miniscrew systems in various thickness of artificial bone block using different measurement tools.

METHODS

Two types of miniscrews (15 Tomas and 15 AbsoAnchor) were placed in artificial bone block with different thickness of 1.5, 2.0, 3.0 mm. Values of maximum insertion torque, removal torque, Periotest, implant stability quotient, static stiffness, dynamic stiffness, and energy dissipation ability were assessed for each miniscrew system.

FINDINGS

The maximum insertion torque, removal torque, implant stability quotient, static and dynamic stiffness values significantly increased when the miniscrews were placed in thicker bone block while Periotest values decreased. The static stiffness, Periotest and implant stability quotient values were significantly correlated each other and also with other mechanical properties (p < 0.001) except tan δ (p > 0.35). However, the slopes of some correlations and absolute values of measurement were significantly different dependent on the miniscrew types (p < 0.025).

INTERPRETATION

The current findings suggest that miniscrew type-dependent calibrations are required to estimate mechanical stability of the miniscrew systems despite the utilization of same measurement tool.

Resonant frequency analysis of dental implants

Dental implant stability influences the decision on the determination of the duration between implant insertion and loading. This work investigates the resonant frequency analysis by means of a numerical model. The investigation is done numerically through the determination of the eigenfrequencies and performing steady state response analyses using a commercial finite element package. A peri-implant interface, of simultaneously varying stiffness, density and layer thickness is introduced in the numerical 3D model in order to probe the sensitivity of the eigenfrequencies and steady state response to an evolving weakened layer, in an attempt to identify the bone reconstruction around the implant. For the first two modes, the resonant frequency is somewhat insensitive to the healing process, unless the weakened layer is rather large and compliant, like in the very early stages of the implantation. A "Normalized Healing Factor" is devised in the spirit of the Implant Stability Quotient, which can identify the healing process especially at the early stages after implantation. The sensitivity of the resonant frequency analysis to changes of mechanical properties of periprosthetic bone tissue seems relatively weak. Another indicator considering the amplitude as well as the resonance frequency might be more adapted to bone healing estimations. However, these results need to be verified experimentally as well as clinically.

Positive modulation of osteogenesis on a titanium oxide surface incorporating strontium oxide: An in vitro and in vivo study

Surface chemistry and topography can determinatively affect the osseointegration of dental implants. Strontium (Sr) has a significant effect on the promotion of bone formation and inhibitation of bone resorption. The emphasis of this study lies on the evaluation of a new surface treatment that aims to improve the early osseointegration of dental implantation both in vitro and in vivo. A hydrothermal method was used to prepare an SrTiO₃ incorporation on sandblasted large-grit double acid-etched (SLA) titanium surfaces in SrCl₂ solution. The composition and morphology of the SrTiO₃ doped surface were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy，and scanning electron microscopy. In addition, the external release figure of Sr was examined by inductively coupled plasma mass spectrometry. The proliferation, adhesion and differentiation of MC3T3-E1 cells on this surface were evaluated in vitro and presented a significant increase in SLA-Sr group compared with that in SLA group. An in vivo study in 24 New Zealand rabbits indicated a remarkable growth in the volume of direct bone-to-implant contact and peri-implant bone in SLA-Sr group, which were compared with SLA group after 3 and 6 weeks, and removal torque tests exhibited a higher torque removal value of SLA-Sr implants. The study gave the result that the biological effect of SLA-Sr implants was significantly superior to that of the SLA implants at the early stage of osseointegration.

Relationship between cortical bone thickness and implant stability at the time of surgery and secondary stability after osseointegration measured using resonance frequency analysis

Purpose

It has been suggested that resonance frequency analysis (RFA) can measure changes in the stability of dental implants during osseointegration. This retrospective study aimed to evaluate dental implant stability at the time of surgery (primary stability; PS) and secondary stability (SS) after ossseointegration using RFA, and to investigate the relationship between implant stability and cortical bone thickness.

Methods

In total, 113 patients who attended the Tohoku University Hospital Dental Implant Center were included in this study. A total of 229 implants were placed in either the mandibular region (n=118) or the maxilla region (n=111), with bone augmentation procedures used in some cases. RFA was performed in 3 directions, and the lowest value was recorded. The preoperative thickness of cortical bone at the site of implant insertion was measured digitally using computed tomography, excluding cases of bone grafts and immediate implant placements.

Results

The mean implant stability quotient (ISQ) was 69.34±9.43 for PS and 75.99±6.23 for SS. The mandibular group had significantly higher mean ISQ values than the maxillary group for both PS and SS (P<0.01). A significant difference was found in the mean ISQ values for PS between 1-stage and 2-stage surgery (P<0.5). The mean ISQ values in the non-augmentation group were higher than in the augmentation group for both PS and SS (P<0.01). A weak positive correlation was observed between cortical bone thickness and implant stability for both PS and SS in all cases (P<0.01).

Conclusions

Based on the present study, the ISQ may be affected by implant position site, the use of a bone graft, and cortical bone thickness before implant therapy.

Combination Use of BMP2 and VEGF165 Promotes Osseointegration and Stability of Titanium Implants in Irradiated Bone

Background

Clinical data demonstrated that failure rate of titanium implant in irradiated bone was 2-3 times higher than that in nonirradiated bone and it is difficult to get the ideal results in irradiated bone.

Purpose

The aim of the study was to investigate the effects of HBO, BMP2, VEGF165, and combined use of BMP2/VEGF165 on osseointegration and stability of titanium implant in irradiated bone.

Materials and Methods

Sixty rabbits were randomly assigned to 5 groups (control group, HBO group, VEGF165 group, BMP2 group, and BMP2/VEGF165 group) after receiving 15 Gy radiation. Implant surgery was performed on tibias eight weeks later. They were sacrificed at two or eight weeks after operation. Implant stability, calcium, and ALP activity in serum, the ratio of bone volume to total volume, the rate of bone growth, and gene expression were assessed.

Result

There was no mortality and no implants failed during the experiment. Implant stability was significantly compromised in the control group compared to the other four experimental groups, and the BMP2/VEGF165 group had the highest implant stability. HBO, BMP2, and VEGF165 significantly increased BV/TV and the rate of bone growth, while the BMP2/VEGF165 showed the best effect among groups. The expression of RUNX2 in HBO, BMP2, and VEGF165/BMP2 group was higher than that in the VEGF165 and control groups at two weeks. The expression of OCN in HBO, BMP2, VEGF165, and VEGF165/BMP2 groups was higher than that in the control group, and the gene expression of CD31 was higher in HBO, VEGF165, and BMP2/VEGF165 groups than that in control and BMP2 groups.

Conclusion

HBO, BMP2, and VEGF165 could increase bone formation around the implant and improved the implant stability in irradiated bone. The combination use of BMP2 and VEGF165 may be promising in the treatment of implant patients with radiotherapy.

Clinical Assessment of Dental Implant Stability During Follow-Up: What Is Actually Measured, and Perspectives

The optimization of loading protocols following dental implant insertion requires setting up patient-specific protocols, customized according to the actual implant osseointegration, measured through quantitative, objective methods. Various devices for the assessment of implant stability as an indirect measure of implant osseointegration have been developed. They are analyzed here, introducing the respective physical models, outlining major advantages and critical aspects, and reporting their clinical performance. A careful discussion of underlying hypotheses is finally reported, as is a suggestion for further development of instrumentation and signal analysis.

Evaluation of dental implant stability in bone phantoms: Comparison between a quantitative ultrasound technique and resonance frequency analysis

BACKGROUND

Resonance frequency analyses and quantitative ultrasound methods have been suggested to assess dental implant primary stability.

PURPOSE

The purpose of this study was to compare the results obtained using these two techniques applied to the same dental implants inserted in various bone phantoms.

MATERIALS AND METHODS

Different values of trabecular bone density and cortical thickness were considered to assess the effect of bone quality on the respective indicators (UI and ISQ). The effect of the implant insertion depth and of the final drill diameter was also investigated.

RESULTS

ISQ values increase and UI values decrease as a function of trabecular density, cortical thickness and the screwing of the implant. When the implant diameter varies, the UI values are significantly different for all final drill diameters (except for two), while the ISQ values are similar for all final drill diameters lower than 3.2 mm and higher than 3.3 mm. The error on the estimation of parameters with the QUS device is between 4 and 8 times lower compared to that made with the RFA technique.

CONCLUSIONS

The results show that ultrasound technique provides a better estimation of different parameters related to the implant stability compared to the RFA technique.

Comparison of Resonance Frequency Analysis and of Quantitative Ultrasound to Assess Dental Implant Osseointegration

Dental implants are widely used in the clinic. However, there remain risks of failure, which depend on the implant stability. The aim of this paper is to compare two methods based on resonance frequency analysis (RFA) and on quantitative ultrasound (QUS) and that aim at assessing implant stability. Eighty-one identical dental implants were inserted in the iliac crests of 11 sheep. The QUS and RFA measurements were realized after different healing times (0, 5, 7, and 15 weeks). The results obtained with the QUS (respectively RFA) method were significantly different when comparing two consecutive healing time for 97% (respectively, 18%) of the implants. The error made on the estimation of the healing time when analyzing the results obtained with the QUS technique was around 10 times lower than that made when using the RFA technique. The results corresponding to the dependence of the ISQ versus healing time were significantly different when comparing two directions of RFA measurement. The results show that the QUS method allows a more accurate determination of the evolution of dental implant stability when compared to the RFA method. This study paves the way towards the development of a medical device, thus providing a decision support system to dental surgeons.

Graphene onto medical grade titanium: an atom-thick multimodal coating that promotes osteoblast maturation and inhibits biofilm formation from distinct species

The time needed for the osseointegration of titanium implants is deemed too long. Moreover, the bacterial colonization of their surfaces is a major cause of failure. Graphene can overcome these issues but its wet transfer onto substrates employs hazardous chemicals limiting the clinical applications. Alternatively, dry transfer technique has been developed, but the biological properties of this technique remain unexplored. Here, a dry transfer technique based on a hot-pressing method allowed to coat titanium substrates with high-quality graphene and coverage area >90% with a single transfer. The graphene-coated titanium is cytocompatible, did not induce cell membrane damage, induced human osteoblast maturation (gene and protein level), and increased the deposition of mineralized matrix compared to titanium alone. Moreover, graphene decreased the formation of biofilms from Streptococcus mutans, Enterococcus faecalis and even from whole saliva on titanium without killing the bacteria. These findings confirm that coating of titanium with graphene via a dry transfer technique is a promising strategy to improve osseointegration and prevent biofilm formation on implants and devices.

Study to assess the relationship between insertion torque value and implant stability quotient and its influence on timing of functional implant loading

Purpose:

One of the crucial requirements for the success of implants is to achieve good stability. Two well-accepted quantitative methods to assess implant stability, the insertion torque value (ITV), and resonance frequency analysis (RFA) can be a valuable adjunct to radiological and clinical examination. This study was conducted to assess the relationship between ITVs and implant stability quotient (ISQ) and its influence on timing of functional implant loading, as well as to determine the effect of some of the factors on the stability of implants.

Materials and Methods:

Forty implants were inserted in 37 patients in the posterior mandibular region according to conventional protocol and allowed to heal by placing a healing abutment at the time of placement. For each implant, ITV was measured at the time of the implant placement by manual torque wrench (Nobel Biocare), and the ISQ value was measured by using resonance frequency analyzer (Osstell-ISQ; Integration Diagnostics) at the baseline levels, 3^rd week, 7^th week, 11^th week, and 15^th week interval.

Results:

The correlation between ITV and ISQ was found to be moderately positive and significant (r = 0.399) (P = 0.000). The correlation of ITV value at baseline and ISQ values recorded at the subsequent weeks was also found to be statistically significant at week 3 (r = 0.376) (P = 0.000) and week 7 (r = 0.327) (P = 0.000).

Conclusion:

It can be concluded from this study that there is a positive and statistically significant correlation between the ITV and ISQ values.

Immediate mechanical stability of threaded and porous implant systems

BACKGROUND

Primary stability of a dental implant system is an essential factor to maintain its long-term success. Thus, the objective of this study was to examine whether primary stability is different between threaded and porous dental implant systems placed in artificial bone blocks and human cadaveric mandibular bone.

MATERIALS AND METHODS

Forty-two threaded and 42 highly porous dental implants were placed in artificial polyurethane bone foams with 7 different thicknesses (3.5 to 12mm). In addition, 11 threaded and 11 porous implants were installed in 8 edentulous mandibles of human cadavers. Implant stability quotient values, insertion torque, static and dynamic stiffness, and viscoelastic tan δ of each implant system were measured. Mean gray values were obtained at the implantation sites in the human mandible.

FINDINGS

The porous implant group had substantially lower implant stability quotient values and insertion torque values than the threaded implant group that were equal or >5.5mm in thickness of the artificial bone block (p<0.026) with the exception of 8.5mm thickness, while static and dynamic stiffness values were not different between the two implant groups greater than 5.5mm in thickness (p>0.132). Static and dynamic stiffness values of the porous group were significantly greater than the thread group in the human mandibular bone (p<0.015).

INTERPRETATION

The porous layer supports axial loading better than lateral and shear loading of the dental implant system. This result indicates that trabecular shaped architecture of the porous layer may provide sufficient anchorage compromising reduction of the axial primary stability of the porous implant system to be comparable with the threaded implant system.

Secondary implant stability outcome of immediate versus late placed variable-thread implants in the maxilla. A retrospective cohort study

Background

The healing of xenograft augmentated intra-alveolar gaps following immediate implant placement (IMIP) after tooth extraction is likely to differ in time and density compared to the native bone part that directly contacts the implant.

Material and Methods

Secondary implant stability (SIS) data recorded 2-3 months following a late implant placement protocol (LIP) (n= 43) and 6-8 months following an immediate implant placement protocol (IMIP) (n=33) of variable-thread implants (Nobel Active™) in the maxilla were retrospectively collected from files of 63 patients (42 females, 21 males). Statistical analysis was performed using a generalized estimating equation model (GEE). Data split-up according to implant diameter (RP, Ø= 4.3mm) , narrow platform (NP, Ø= 3.5mm) was adopted.

Results

For NP implants, the mean ISQ (±SD) values were 70.84 (±4.86) in LIP group and 72.41 (±3.89) in the IMIP group. For RP implants, mean ISQ (±SD) values were 73.45 (±8.77) in the LIP group and 75.93 (±5.73) in the IMIP group. Significant effect of treatment modus in favour of the IMIP and gender in favour of males and implant position was noted (p<0.05).

Conclusions

SIS following a IMIP protocol after 6-8 months is comparable to LIP protocol after 2-3 months. A minor ISQ outcome difference in favour of the IMIP protocol can be attributed to a difference in hard tissue alteration during healing of the xenograft part.

Key words:Secondary implant stability, RFA, Osstell Mentor, variable thread implants, Nobel Active, Bio-Oss, immediate implant placement, late implant placement, non-submerged healing, gap.

The rate and stability of mandibular block bone graft in recent 5 years

Background

The purposes of the present study were to compare implant stabilities of mandibular block bone graft and bovine bone graft and to evaluate influencing factors for implant stability in mandibular block bone (MBB) graft.

Methods

This retrospective study investigated 1224 cases and 389 patients treated by one surgeon in the Department of Oral and Maxillofacial Surgery of Pusan National University Dental Hospital (Yangsan, Korea) between January 2010 and December 2014. Proportions that MBB graft cases constitute in all implant restoration cases and in all bone graft cases were measured. Implant stability quotient (ISQ) values were achieved by the same surgeon before loading. The average ISQ values of the experimental groups were compared. In addition, ISQ values of influencing factors, such as age, sex, implant size, and implant placement site, were compared within the MBB group using Osstell^TM Mentor (Osstell®, Göteborg, Sweden). Paired t test and ANOVA were conducted for statistical analysis with a significance level of 0.05.

Results

Fifty-five percent of all implant restoration cases performed bone graft while MBB cases constituted 34% of all implant restoration cases and 61% of all bone graft cases. Comparing ISQ values according to bone graft materials, the MBB group manifested sufficient implant stability by presenting comparable ISQ value to that of the experimental group without bone graft. Among the reviewed factors, females, mandibular molar regions, and implants in larger diameter displayed greater implant stabilities.

Conclusions

Satisfactory implant stability was accomplished upon administration of MBB graft. Within the limitation of this study, gender, implant site, and implant diameter were speculated to influence on implant stability in MBB graft.

Resonance frequency analysis of dental implants placed at the posterior maxilla varying the surface treatment only: A randomized clinical trial

BACKGROUND

Chemical modifications of the dental implant surface that improve the wettability result in a faster and better osseointegration.

PURPOSE

The aim of this randomized clinical trial was to evaluate the implant stability quotient (ISQ) of implants with similar designs, treated with 2 surfaces, sandblasted acid-etched (SAE) and hydrophilic SAE, within the initial 16 weeks of healing.

MATERIAL AND METHODS

A total of 64 implants (32 SAE-control group and 32 modified SAE-test group) with the same design, length, and diameter (conical and compressive, 4.3 × 10 mm) were inserted into the posterior maxillae of 21 patients partially edentulous. The ISQ values were collected at post-surgery (T0), 1 week (T1), 2 weeks (T2), 3 weeks (T3), 5 weeks (T4), 8 weeks (T5), 12 weeks (T6), and 16 weeks (T7).

RESULTS

None of the implants failed. Test group presented ISQ values higher than the control group (ANOVA-P < .01) from T5 to T7. When comparing groups regarding the amount of time required to achieve ISQ ≥ 70 as a reference, there was a statistically significant difference (cox regression-P < .01), and a hazard ratio of 2.24 (CI 1.62-3.11). At the 1-year follow-up, there was a drop out of 1 patient, and 2 implants were no longer evaluated. Survival rate for both groups was 100% at the 1-year follow-up.

CONCLUSIONS

The current study suggests that implants with hydrophilic surface (modified SAE) integrate faster than implants with SAE surface. The stability gain of the test group was 2.24 times faster than the control group after 5 weeks of evaluation at the posterior region of the edentulous maxillae.

Correlation between Implant Stability Quotient (ISQ) with Clinical and Histological Aspects of Dental Implants Removed for Mobility

Dental implants are a successful treatment modality for missing teeth; however, failures do occur. These failures can occur early in the healing process after primary stability has been achieved at the time of implant placement, or after initial bone remodeling and new bone growth have taken place. The ability to detect implants that are failing or will fail is still not possible. The aim of the present study is to see if correlations exist between RFA values and histologic and histochemical evaluation of the human retrieved implants for failure. In a 5 year period, 37 root form implants were retrieved because of mobility and underwent histological examination. Thin ground sections were obtained from each implant. All the implants had been removed with a 5 mm trephine. In all cases a peri-implant radiolucency was present. Before implant retrieval, the implant stability was evaluated with Osstell (Integration Diagnostics AB, Gothenburg, Sweden). All the implants were not osseointegrated clinically and mobility was present. Radiographically, bone loss was observed around the implants and the mean ISQ values was 37 (+/- 2.7). A scarce inflammatory cell infiltrate was present in the connective tissue of some specimens. In about 10 percent of specimens, the epithelium tended to surround the total perimeter of the implant. These data suggest that implants with an ISQ<40 are irretrievably lost and there is no possibility to save them. A statistically significant correlation was found between an ISQ<36 and irretrievably failed implants.

A resonance frequency analysis of sandblasted and acid-etched implants with different diameters: a prospective clinical study during the initial healing period

Purpose

The possibility of immediate or early loading has become popular in implant dentistry. A prerequisite for the immediate or early loading of an implant prosthesis is the achievement of initial stability in the implant. Moreover, in response to clinicians' interest in verifying clinical stability to determine the optimal time point for functional loading, a non-invasive method to assess implant stability has been developed on the basis of resonance frequency analysis (RFA). The primary objective of this study was to monitor the stability of sandblasted, large-grit, and acid-etched (SLA) implants with different diameters during the early phases of healing by RFA. The secondary objective was to evaluate how the initial stability of implants varied depending on different surface modifications and other contributing factors.

Methods

Thirty-five implants (25 SLA implants and 10 resorbable blasting media [RBM] implants) placed in 20 subjects were included. To measure implant stability, RFA was performed at baseline and at 1, 2, 3, 4, 6, and 10 weeks after surgery.

Results

The longitudinal changes in the implant stability quotient (ISQ) values were similar for the SLA implants with different diameters and for the RBM implants. During the initial healing period, the ISQ decreased after installation and reached its lowest values at 1 week and 2 weeks, respectively. The mean ISQ values in the SLA implants were significantly higher in Ø 5.0 mm implants than in Ø 4.0 mm implants. Men showed a higher ISQ than women. Mandibular sites showed a higher ISQ than maxillary sites.

Conclusions

All implants used in this study are suitable for immediate or early loading under appropriate indications. A wider diameter and SLA surface treatment of implants could improve the stability, if the implant is fixed with at least 30 Ncm of insertion torque.

Evaluation of the osseointegration of dental implants coated with calcium carbonate: an animal study

In an attempt to overcome the limitations of titanium in dental and orthopaedic clinical applications, a new method has been developed to prepare calcium carbonate coatings on sandblasted and acid-etched (SA) titanium implants. The purpose of this study was to investigate the effect of calcium carbonate-SA (CC-SA) implants on osseointegration in vivo. The surfaces of SA and CC-SA implants were characterised for surface morphology and surface chemistry. Subsequently, these two kinds of implants were implanted in the femoral condyles of rabbits. The implants were retrieved and prepared for histological and histomorphometric evaluation 1, 2, 4, 8 and 12 weeks after implantation. Significantly higher values of bone-to-implant contact of the entire implant except the gap area (BIC_ALL) and the bone-to-implant contact of the gap area (BIC_GAP) were found in animals with the CC-SA implants than in those with the SA implants at 4 weeks. Higher values of total gap bone were found in those with the CC-SA implants than in those with the SA implants at 1, 2 and 4 weeks. In conclusion, the current findings demonstrate that the calcium carbonate coating can improve and accelerate the early ingrowth of bone and osseointegration at the early healing phase. This may reduce clinical healing times and thus improve implant success rates.

Monitoring the Changes of Material Properties at Bone-Implant Interface during the Healing Process In Vivo: A Viscoelastic Investigation

The aim of this study was to monitor the changes of viscoelastic properties at bone-implant interface via resonance frequency analysis (RFA) and the Periotest device during the healing process in an experimental rabbit model. Twenty-four dental implants were inserted into the femoral condyles of rabbits. The animals were sacrificed immediately after implant installation or on day 14, 28, or 56 after surgery. Viscoelastic properties at bone-implant interface were evaluated by measuring the implant stability quotient (ISQ) using RFA and by measuring the Periotest values (PTVs) using the Periotest device. The bone/implant specimens were evaluated histopathologically and histomorphometrically to determine the degree of osseointegration (BIC%). The BIC% values at different time points were then compared with the corresponding ISQ values and PTVs. The mean ISQ value increased gradually and reached 81 ± 1.7 on day 56, whereas the mean PTV decreased over time, finally reaching −0.7 ± 0.5 on day 56. Significant correlations were found between ISQ and BIC% (r = 0.701, p < 0.001), PTV and BIC% (r = −0.637, p < 0.05), and ISQ and PTV (r = −0.68, p < 0.05). These results show that there is a positive correlation between implant stability parameters and peri-implant-bone healing, indicating that the RFA and Periotest are useful for measuring changes of viscoelastic properties at bone-implant interface and are reliable for indirectly predicting the degree of osseointegration.

Customized SmartPeg for measurement of resonance frequency of mini dental implants

Background

One-piece narrow diameter implants (NDIs) have been recommended as “Single-tooth replacements in the anterior zones, single posterior, multiple-unit fixed dental prosthesis (FDP), edentulous jaws to be rehabilitated with FDP, and edentulous jaws rehabilitation with overdentures in situations with reduced mesiodistal space or reduced ridge width.” (ITI consensus 2013). Since NDIs can be immediately loaded, it is important to be able to carry out stability testing. We developed and validated a customized SmartPeg for this type of implant to measure the Implant Stability Quotient (ISQ). The ISQ of mini dental implants (MDIs) was measured and compared with the stability of standard and in a rabbit model.

Objective

The aim of the study is to test the feasibility of a customized SmartPeg for resonance frequency measurement of single-piece mini dental implants and to compare primary stability of a standard and the mini dental implant (3M™ESPE™ MDI) in a rabbit model after 6 weeks of healing.

Methods

Eight New Zealand white rabbits were used for the study. The protocol was approved by the McGill University Animal Ethics Review Board. Sixteen 3M™ESPE™ MDI and equal number of standard implants (Ankylos® Friadent, Dentsply) were inserted into the tibia/femur of the rabbits and compared. Each rabbit randomly received two 3M™ESPE™ MDI and two Ankylos® implants in each leg. ISQ values were measured with the help of an Osstell ISQ device using custom-made SmartPegs for the MDIs and implant-specific SmartPegs™ (Osstell) for the Ankylos®. Measurements were obtained both immediately following implant placement surgery and after a 6-week healing period. Each reading was taken thrice and their average compared using Wilcoxon matched pairs signed-rank tests.

Results

The median ISQ and interquartile range (IQR) values were 53.3 (8.3) at insertion and 60.5 (5.5) at 6 weeks for the 3M™ESPE™MDI and, respectively, 58.5 (4.75) and 65.5 (9.3) for the Ankylos® implant. These values also indicate that both types of implants achieved primary and secondary stability, and this is supported by histological data. ISQ values of both 3M™ESPE™ MDI and Ankylos® increased significantly from the time of insertion to 6 weeks post-insertion (p < 0.05).

Conclusions

The new custom-made SmartPeg is suitable for measuring the Implant Stability Quotient of 3M™ESPE™MDIs. The primary stability of 3M™ESPE™MDIs is similar to the primary stability attained by standard implants in the rabbit tibia.

Relation between the stability of dental implants and two biological markers during the healing period: a prospective clinical study

OBJECTIVES

The purposes of this study were to examine the correlation between the stability of dental implants and bone formation markers during the healing period and to monitor the stability of dental implants using the resonance frequency analysis (RFA) method. The null hypothesis of the study is no correlation between the stability of dental implant and bone formation markers.

METHODS

The study is a prospective clinical study during the 3-month healing period of implant. At implant placement (PW Plus, Nakhon Pathom, Thailand) and after 1, 2, 3, 4, 6, 8, 10, and 12 weeks, RFA assessments were performed and gingival (GCF)/peri-implant crevicular fluids (PICF) were collected from ten patients. The level of osteocalcin (OC) was measured by using ELISA kits, and the level of alkaline phosphatase (ALP) activity was measured by colorimetric analysis. Repeated measures analysis of variance, the Friedman test, the Mann-Whitney U test, and the Pearson correlation were performed for data analysis.

RESULTS

There was a statistical decrease in the mean implant stability quotient (ISQ) values between 1 and 3 weeks (P < 0.05). The ISQ values recovered to the initial values at 4 weeks. There was no statistical difference in the ALP level at each measurement, while there was a statistical increase in the OC level at 6, 8, 10, and 12 weeks when compared with 1 week (P < 0.05). There was a significant correlation between ALP levels and ISQ values (r = 0.226, P < 0.05). There was a statistically significant correlation between OC levels and ISQ values at 1-12 weeks (r = 0.245, P < 0.05).

CONCLUSIONS

The ISQ values were weakly correlated with both ALP and OC. The three-thread-design implant showed a high stability through healing period.

Immediate vs non-immediate loading post-extractive implants: a comparative study of implant stability quotient (ISQ)

PURPOSE

This study aims to evaluate differences in implant stability between post-extractive implants vs immediately placed post-extractive implants by resonance frequency analysis (RFA).

MATERIALS AND METHODS

Patients were grouped into two different categories. In Group A 10 patients had an immediate post-extractive implant, then a provisional, acrylic resin crown was placed (immediate loading). In Group B (control group) 10 patients only had an immediate post-extractive implant. Both upper and lower premolars were chosen as post-extractive sites. Implant Stability Quotient (ISQ) was measured thanks to RFA measurements (Osstell®). Five intervals were considered: immediately after surgery (T0) and every four weeks, until five months after implant placement (T1, T2, T3, T4,T5). A statistical analysis by means of Student's T-test (significance set at p<0.05) for independent sample was carried out in order to compare Groups A and B.

RESULTS

The ISQ value between the two groups showed a statistically significant difference (p<0.02) at T1. No statistically significant difference in ISQ was assessed at T0, T2, T3, T4 and T5.

CONCLUSIONS

After clinical assessment it is possible to confirm that provisional and immediate prosthetic surgery in post-extraction sites with cone-shaped implants, platform-switching abutment and bioactive surface can facilitate osseointegration, reducing healing time.

Assessment of implant stability following sinus lift procedures with different grafting materials

OBJECTIVE

The objective of this research was to evaluate implant stability following sinus lift with two grafting materials, and to compare it with the results obtained for the implants placed in a pristine posterior maxilla.

MATERIALS AND METHODS

The study included 44 healthy patients with an existing indication for sinus lift procedure (test group). 46 implants were placed following sinus lift with a pure-phase beta-tricalcium phosphate, while 39 implants were placed following augmentation with 60% hydroxyapatite with 40% beta-tricalcium phosphate material. The control group consisted of 48 healthy patients who were treated with 85 implants but without bone augmentation in posterior maxilla. Astra Tech OsseoSpeed implants were placed in all subjects. Resonance frequency analysis was used in both groups for determining implant stability 4 months after insertion. A mean implant stability quotient (ISQ) was calculated on the basis of 3 measurements.

RESULTS

No statistical difference was observed in ISQ values of implants placed with and without augmentation procedure (p=0,789). Statistically significant difference was not found when ISQ values of implants placed following particular grafting material were compared with ISQ values of corresponding implants in a pristine bone (p=0.697 and p=0.402).

CONCLUSIONS

This study demonstrated that the implant stability is comparable among implants placed in the posterior maxilla regardless of sinus lift and grafting procedure. Implants placed in the grafted posterior maxilla can be predictably loaded as the implants placed in a non-grafted, pristine maxilla.

The evaluation of prepared microgroove pattern by femtosecond laser on alumina-zirconia nano-composite for endosseous dental implant application

Ceramic dental materials, especially alumina (20 %vol)-yttrium stabilized tetragonal zirconia poly crystal (A-Y-TZP20), have been considered as alternatives to metals for endosseous dental implant application. For increasing the bone-to-implant contact as well as the speed of bone formation, a new surface modification can be effective. The aim of this study was to design microgroove patterns by femtosecond laser on A-Y-TZP20 nano-composite disks for endosseous dental implant application. The phase composition and the morphology of the A-Y-TZP20 nano-composite samples were characterized using X-ray diffraction and Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy techniques. Statistical analysis was submitted to Kolmogorov-Smirnov test and Student's t test for independent variables, with a 5 % significance level. EDAX analysis revealed a significant decrease in the relative content of contaminants like carbon (p < 0.05) in laser surface-treated group as compared to non surface-treated group. X-ray diffraction did not show any change in the crystalline structure induced by laser processing. It was concluded that the femtosecond laser is a clean and safe method for surface modification of A-Y-TZP20.

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.

The Effect of Flapless and Full-thickness Flap Techniques on Implant Stability During the Healing Period

Purpose : When soft tissue flaps are reflected for implant placement, the blood supply from the periosteum to the bone is disrupted. The aim of this study was to compare the effects of the flapless (FL) and full-thickness flap (FT) techniques on implant stability. Methods : Nine patients received 22 implants. The implants were placed using the FL technique on the contralateral side of the jaw; the FT technique was used as the control technique. Resonance frequency analysis (RFA) was performed at the time of implant placement and at 6 and 12 weeks after implant placement. RFA values were compared between the FL and FT groups and between time intervals in the same group. Results : The median (interquartile range [IQR]) RFA values at the time of implant placement were 75.00 (15.00) for the FL technique and 75.00 (9.00) for the FT technique. At 6 weeks, the median (IQR) values were 79 (3.30) for the FL technique and 80 (12.70) for the FT technique. At 12 weeks, the median (IQR) values were 82.3 (3.30) for the FL technique and 82.6 (8.00) for the FT technique. There were no significant differences between the 2 techniques at the time of implant placement, after 6 weeks or after 12 weeks, with p values of 0.994, 0.789, and 0.959, respectively. There were significant differences between the RFA values at the time of implant placement and after 6 weeks for the FL technique (p=0.028) but not for the FT technique (p=0.091). There were also significant differences between the RFA values at 6 weeks and the RFA values at 12 weeks for the FL technique (p=0.007) and for the FT technique (p=0.003). Conclusion : Periosteum preservation during the FL procedure will speed up bone remodeling and result in early secondary implant stability as well as early loading.

Osstell Resonance Frequency Measurement Values as a Prognostic Factor in Implant Dentistry

Resonance frequency analysis (RFA) using the Osstell device (Osstell AB, Gothenburg, Sweden) has been advocated for quantifying implant stability on a relative scale of implant stability quotients (ISQ). It was the goal of this prospective clinical study to evaluate whether a certain ISQ level, at the time an implant is placed, correlates with successful osseointegration as some have claimed. Four hundred ninety-five implants (Straumann AG, Basel, Switzerland), varying in length and diameter, were placed in a private practice, strictly adhering to the implant manufacturer's surgical protocol. After placement and after healing periods of 42 days in the mandible and 56 days (implant manufacturer's protocol) in the maxilla, implant stability was measured using RFA. After healing, implants were torqued forward at 35 Ncm and allowed to heal further if the patients felt discomfort. Statistical analysis of the data obtained was based on Welch tests and Kolmogorov-Smirnow tests (level of significance α = 0.05). Results showed that 432 implants were osseointegrated after the predefined healing periods while 8 implants were lost and, in 55 cases, healing was prolonged. Both at insertion (P = .025) and after healing (P &lt; .001), successful implants showed significantly different ISQ values as compared to implant failures or implants with prolonged healing. However, overlapping ISQ distributions at implant insertion demonstrated that there was no correlation among the data that could be used to predict successful osseointegration. Within the limits of this study, the prognostic value of ISQ values appears to be ambiguous.

Impact of Bone Quality and Implant Type on the Primary Stability: An Experimental Study Using Bovine Bone

The purpose of this in vitro study was to compare the primary stability and removal torque of bone level and tissue level implants in different bone qualities. Twenty tissue level and bone level implants (3.3 × 10 mm and 4.1 × 10 mm) were used for assessing the stability in type II and type IV bone. Forty bovine rib blocks were used in this study. The primary stability of the implant was measured by the resonance frequency using an Osstel device. The removal torque values (RTV) of the implants was assessed using a digital torque gauge instrument. The implant stability quotient (ISQ) values and the RTV showed a marginally higher stability with bone level implants as compared to tissue level implants. However, these differences were not statistically significant in both type of bone used (P &gt; 0.05). On the other hand, compared to type IV, type II bone showed significant differences in the ISQ (P &lt; 0.01) and RTV (P &lt; 0.001) of bone level and tissue level implants. The study concluded that bone quality is an important factor in establishing primary stability than the implant dimension. Bone level and tissue level implants of same dimensions can be selected based on the esthetic demands since they showed similar mechanical properties.

Associations of Resonance Frequency Analysis with Dynamic Mechanical Analysis of Dental Implant Systems

BACKGROUND

Resonance frequency analysis (RFA) has been introduced as a noninvasive method to clinically estimate the stability of dental implant systems.

PURPOSE

The objective of this study was to examine whether implant stability quotient (ISQ) values of RFA can account for mechanical stability of the dental implant system, which is assessed using dynamic mechanical analysis (DMA).

MATERIALS AND METHODS

Fifty-seven screw-type titanium dental implants were placed in artificial polyurethane foams with seven different thicknesses (3.5 to 12 mm) and eight edentulous mandibles of human cadavers (four men and four women, 79.11 ± 13.48 years). After the ISQ values, insertion torque, and static stiffness of each implant system were measured, the DMA was performed to assess dynamic stiffness and viscoelastic tan δ.

RESULTS

The ISQ value had strong positive correlations with thickness, insertion torque, static and dynamic stiffness, and a negative correlation with tan δ of implant systems in artificial bone blocks (r = 0.769 to 0.992, p < .043). However, the ISQ value was correlated with only the insertion torque of implant systems in human mandibles (p < .049).

CONCLUSION

The ISQ values could reflect mechanical stability of the dental implant system under the controlled condition of homogeneous density in simple dimensions.

Ag-plasma modification enhances bone apposition around titanium dental implants: an animal study in Labrador dogs

Dental implants with proper antibacterial ability as well as ideal osseointegration are being actively pursued. The antimicrobial ability of titanium implants can be significantly enhanced via modification with silver nanoparticles (Ag NPs). However, the high mobility of Ag NPs results in their potential cytotoxicity. The silver plasma immersion ion-implantation (Ag-PIII) technique may remedy the defect. Accordingly, Ag-PIII technique was employed in this study in an attempt to reduce the mobility of Ag NPs and enhance osseointegration of sandblasted and acid-etched (SLA) dental implants. Briefly, 48 dental implants, divided equally into one control and three test groups (further treated by Ag-PIII technique with three different implantation parameters), were inserted in the mandibles of six Labrador dogs. Scanning electron microscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma optical emission spectrometry were used to investigate the surface topography, chemical states, and silver release of SLA- and Ag-PIII-treated titanium dental implants. The implant stability quotient examination, Microcomputed tomography evaluation, histological observations, and histomorphometric analysis were performed to assess the osseointegration effect in vivo. The results demonstrated that normal soft tissue healing around dental implants was observed in all the groups, whereas the implant stability quotient values in Ag-PIII groups were higher than that in the SLA group. In addition, all the Ag-PIII groups, compared to the SLA-group, exhibited enhanced new bone formation, bone mineral density, and trabecular pattern. With regard to osteogenic indicators, the implants treated with Ag-PIII for 30 minutes and 60 minutes, with the diameter of the Ag NPs ranging from 5–25 nm, were better than those treated with Ag-PIII for 90 minutes, with the Ag NPs diameter out of that range. These results suggest that Ag-PIII technique can reduce the mobility of Ag NPs and enhance the osseointegration of SLA surfaces and have the potential for future use.

Assessment of in vitro dental implant primary stability using an ultrasonic method

Dental implants are used for oral rehabilitation. However, there remain risks of failure that depend on the implant stability. The objective of this study is to investigate whether quantitative ultrasound technique can be used to assess the amount of bone in contact with dental implants. Ten implants are first inserted in the bone samples. The 10 MHz ultrasonic response of each implant is measured using a dedicated device and an indicator I is derived based on the amplitude of the signal. Then, the implant is unscrewed by 2 π radians and the measurement is realized again. A statistical analysis of variance was carried out and revealed a significant effect of the amount of bone in contact with the implant on the values of I (p value < 10⁻⁵). The results indicates the feasibility of quantitative ultrasound techniques to assess implant primary stability in vitro.

The effects of elevated hemoglobin A(1c) in patients with type 2 diabetes mellitus on dental implants: Survival and stability at one year

BACKGROUND

The authors conducted a prospective cohort study to determine whether poor glycemic control is a contraindication to implant therapy in patients with type 2 diabetes.

METHODS

The study sample consisted of 117 edentulous patients, each of whom received two mandibular implants, for a total of 234 implants. Implant-retained mandibular overdentures were loaded after a four-month healing period and followed up for an additional one year. The authors assessed implant survival and stability (by means of resonance frequency analysis) relative to glycated hemoglobin A1c (HbA1c) levels, with baseline levels up to 11.1 percent and levels as high as 13.3 percent over one year.

RESULTS

Implant survival rates for 110 of 117 patients who were followed up for one year after loading were 99.0 percent, 98.9 percent and 100 percent, respectively, for patients who did not have diabetes (n = 47), those with well-controlled diabetes (n = 44) and those with poorly controlled diabetes (n = 19). The authors considered the seven patients lost to follow-up as having had failed implants; consequently, their conservative estimates of survival rates in the three groups were 93.0 percent, 92.6 percent and 95.0 percent (P = .6510). Two implants failed at four weeks, one in the nondiabetes group and the other in the well-controlled diabetes group. Delays in implant stabilization were related directly to poor glycemic control.

CONCLUSIONS

The results of this study indicate that elevated HbA1c levels in patients with type 2 diabetes were not associated with altered implant survival one year after loading. However, alterations in early bone healing and implant stability were associated with hyperglycemia.