Influence of defect depth on resonance frequency analysis and insertion torque values for implants placed in fresh extraction sockets: a human cadaver study

Background: Clinical studies show promising outcomes with implants inserted at the time of extraction. However, this often results in an initial bone defect at the marginal region which preferably should heal for an optimal function. Therefore, monitoring of these implants is vital.
Purposes: The aims of this study were to determine the initial stability of implants placed into fresh extraction sockets, and to explore the correlations between the peri-implant bone levels and implant stability parameters.
Materials and Methods: Six human cadaver mandibles including all natural teeth were selected for this study. All natural teeth were gently extracted, and 84 implants were immediately placed into fresh extraction sockets with five different implant depths. The maximum insertion torque values were recorded, and primary implant stability measurements were performed by means of resonance frequency analysis (RFA). The vertical distance between implant/abutment junction and the first bone–implant contact was recorded using a periodontal probe.
Results: It was found that the insertion torque and RFA were 28.9 ± 7 Ncm and 65.6 ± 9 implant stability quotient (ISQ), respectively, for 420 measurements from all 84 implants. Statistically significant correlation was found between insertion torque and ISQ values ( r  = 0.86; p  < .001) for all implants. Both insertion torque and ISQ values dramatically decreased when the amount of peri-implant vertical bone defect increased.
Conclusion: The results of this study demonstrated a linear relationship between peri-implant vertical bone defect depth and RFA value. It is proposed that the RFA method is sensitive to detect changes of the marginal bone level and may be used to monitor healing of peri-implant bone defects.     

Relations between the bone density values from computerized tomography, and implant stability parameters: a clinical study of 230 regular platform implants

Aims: The objective of this study was to determine the relationship between bone density, insertion torque, and implant stability at implant placement. Materials and Methods: One‐hundred and eight patients were treated with 230 Brånemark System implants. A computerized tomography (CT) machine was used for pre‐operative evaluation of the jaw bone for each patient. The maximum insertion torque values were recorded with the OsseoCare equipment. Implant stability measurements were performed with the Osstell machine for only 142 implants. Results: The mean bone density and insertion torque values were 721±254 Hounsfield unit (HU) and 39.1±7 N cm for 230 implants, and the correlation was significant (r=0.664, p<0.001). The mean bone density, insertion torque, and resonance frequency analysis values were 751±257 HU, 39.4±7 Nc m, and 70.5±7 implant stability quotient (ISQ), respectively, for 142 implants. Statistically significant correlations were found between bone density and insertion torque values (p<0.001); bone density and ISQ values (p<0.001); and insertion torque and ISQ values (p<0.001). Conclusion: The bone density values from pre‐operative CT examination may provide an objective assessment of bone quality, and significant correlations between bone density and implant stability parameters may help clinicians to predict primary stability before implant insertion.     

Biomechanical aspects of initial intraosseous stability and implant design: a quantitative micro-morphometric analysis

PURPOSE: The objective of this biomechanical study was to explore the effect of bone micro-morphology on initial intraosseous stability of implants with different designs. MATERIAL AND METHODS: Straumann and Astra Tech dental implants were placed into anterior and posterior regions of completely edentulous maxilla and mandible of a human cadaver. Experiments were undertaken to quantify initial implant stability and bone micro-morphology. Installation torque values (ITVs) and implant stability quotients (ISQs) were measured to determine initial intraosseous implant stability. For quantification of relative bone volume and micro-architecture, sectioned implant-bone and bone core specimens of each implant placement site were consecutively scanned and trabecular bone was analyzed in a micro-computed tomography (micro-CT) unit. Experimental outcomes were evaluated for correlations among implant designs, initial intraosseous implant stability and bone micro-structural parameters. RESULTS: ITVs correlated higher with bone volume fraction (BV/TV) than ISQs, at 88.1% and 68.9% levels, respectively. Correlations between ITVs and micro-morphometric parameters were significant at the 95% confidence level (P<0.05) while ISQs were not. Differences in ITVs, ISQs and BV/TV data in regards to implant designs used were not significant at the 95% confidence level (P>0.05). CONCLUSION: Bone micro-morphology has a prevailing effect over implant design on intraosseus initial implant stability, and ITV is more sensitive in terms of revealing biomechanical properties at the bone-implant interface in comparison with ISQ.     

Osstell ISQTM监测种植体稳定性的临床研究

目的：分析种植体初期稳定系数（ISQi）与植入扭矩值（ITv）在评估初期稳定性中的关系;分析不同初期稳定性种植体在骨愈合期种植体稳定系数（ISQ）的变化趋势。方法：选择牙缺失患者34例,共55枚种植体。应用Osstell ISQTM共振频率分析仪于种植体植入时测量ISQ和记录ITv,并于植入后4周、8周、12周监测ISQ变化。结果： ISQi与ITv存在强正相关性。低初期稳定性组种植体植入后ISQ呈持续上升过程,高初期稳定性组ISQ则呈先降后升趋势,4周降至最低点。结论： Osstell ISQTM能良好评价和监测种植体稳定性, ISQi与ITv均为评价种植体初期稳定性的客观指标,种植体稳定性的变化趋势与初期稳定性范围相关。     

Two alternative surgical techniques for enhancing primary implant stability in the posterior maxilla: a clinical study including bone density, insertion torque, and resonance frequency analysis data

Background: The primary stability of dental implants associated with resistance to micromotion during healing is affected by surgical technique and implant design, which are important especially in the soft bone, where implant failures are more likely. Purposes: This study was designed to compare the parameters associated with implant insertion using two different methods of enhancing implant primary stability and to identify any relationship between these parameters at implant insertion. Materials and Methods: A total of 60 implants were placed in the maxillary posterior regions of 22 patients. The bone densities at the implant sites were recorded using a computerized tomography machine in Hounsfield unit (HU). The maximum insertion torque data were recorded with the Osseocare™ (Nobel Biocare AB, Göteborg, Sweden) equipment, while resonance frequency analysis (RFA) measurements were taken using an Osstell™ (Integration Diagnostics AB, Göteborg, Sweden) machine at implant surgery. Comparisons including HU, Ncm, and implant stability quotient were made between two control groups (C1 and C2), and corresponding four test groups (T1–T4) using thinner drills to enhance primary implant stability. Results: Two implants were lost, meaning an overall implant survival rate of 96.6% after 3 ± 1 years. When compared to control groups, significantly higher mean maximum insertion torque and RFA values were found for corresponding test groups. In addition, strong correlations were observed between the bone density and insertion torque, and implant stability values at implant placement. Conclusion: The results of this study suggest that using thinner drills for implant placement in the maxillary posterior region where bone quality is poor may improve the primary implant stability, which helps clinicians to obtain higher implant survival rates.     

Measurements comparing the initial stability of five designs of dental implants: a human cadaver study

Background: A number of different dental implant designs are currently in clinical use. A successful outcome of implant placement is thought, at least in part, to be due to the primary stability of an implant after placement. Few data are available for comparing the primary stability characteristics of different implant designs. Purpose: This investigation compared the primary stability of five types of endosseous dental implant of varying geometry and surface topography. Materials and Methods: Comparison was made between a standard threaded commercially pure titanium implant (Nobel Biocare AB, Göteborg, Sweden), the Mark II self‐tapping implant (Nobel Biocare AB, Göteborg, Sweden), the Mark IV tapered self‐tapping implant (Nobel Biocare AB, Göteborg, Sweden), the Astra Tioblast (AstraTech AB, Mölndahl, Sweden), and the 3i Osseotite (3I [Implant Innovations Incorporated], Palm Beach, Florida, USA). Fifty‐two fixtures were placed in the maxillary bone of nine unembalmed human cadavers. Implant stability as a function of peak insertion torque and resonance frequency values was recorded for each fixture site after placement. Removal torque was also measured 1‐hour postinsertion. Assessment of bone quality at each site was made. Results: All of the implants tested demonstrated good primary stability in type 2 and 3 bone. The Standard, Mark II, Osseotite, and Tioblast were less stable when placed into bone type 4. The Mark IV implants appeared to maintain a high primary stability even in Type 4 bone. Conclusion: When looking across all bone qualities, the Mark IV implant develops a significantly higher insertion torque than the Standard, Mark II, and Osseotite implant types, and a significantly higher resonance frequency value than the Standard implant, indicating a higher interfacial stiffness at the implant–bone interface.     

Influence of surgical technique,implant shape and diameter on the primary stability in cancellous bone

Summary Achievement of primary stability during surgical placement of dental implants is one of the most important factors for successful osseointegration depending on various anatomical, surgical and implant‐related factors. Resonance frequency analysis (RFA) has been shown as a non‐invasive and objective technique for measuring the stability of implants. The aim of this study was to evaluate the effect of some surgical and implant‐related factors in enhancing primary stability and to estimate a correlation between RFA and insertion torque (IT) in proximal regions of cow ribs representing cancellous bone. Fifteen implant beds were prepared in the most proximal region of six fresh cow ribs. Ninety implants with three different shapes and two different diameters were placed with two different surgical techniques, and the primary stability was compared using RFA and IT. Significantly higher RFA and IT values were achieved when under‐dimensioned drilling was used as the surgical method (P < 0·01); significantly higher IT values were obtained with the use of wider implants (P < 0·01) and partially conical Astra Tech implants showed the highest IT values (P < 0·01). When all the implants were considered, significant correlations between the IT and RFA values were noted (%40·6, P < 0·05). Partially conical implants with a wide diameter to be placed with the modified surgical technique proposed appear to be useful in enhancing the primary stability in cancellous bone.     

Implant design and intraosseous stability of immediately placed implants: a human cadaver study

Objective: The objective of this study was to explore effects of implant macrodesign and diameter on initial intraosseous stability and interface mechanical properties of immediately placed implants. Material and method: Mandibular premolars of four fresh‐frozen human cadavers were extracted. Ø 4.1/4.8 mm ITI® TE®, Ø 4.1 and 4.8 mm solid screw synOcta® ITI® implants were placed into freshly prepared extraction sockets. Resonance frequency analysis was conducted to quantify primary implant stability quotient (ISQ). Installation torque value (ITV) and removal torque value (RTV) of the implants were measured using a custom‐made strain‐gauged torque wrench connected to a data acquisition system at a sample rate of 10,000 Hz. The vertical defect depth around the collar of each implant was measured directly by an endodontic spreader. The bone–implant contact was determined in digitalized images of periapical radiographs and expressed as percentage bone contact. Results: The ISQ values of the TE® implant was higher than the Ø 4.1 mm implant (P<0.01), and comparable with the Ø 4.8 mm implants (P>0.05). ITVs and RTVs of TE® and Ø 4.8 mm implants were higher than the Ø 4.1 mm implant, although the differences between groups were statistically insignificant (P>0.05). The vertical defect depths around all types of implants were similar. In the radiographic analyses, percentage bone–implant contact of the TE® and Ø 4.8 mm implants were comparable at the marginal bone region and both were higher than that of the Ø 4.1 mm ITI® implant. Nonparametric correlations between groups revealed a significant correlation between ITV and RTV (r=0.838; P<0.001), but not between ISQ values and ITVs and RTVs (P>0.05). Conclusion: Immediately placed ITI® TE® implant leads to initial intraosseous stability and interface mechanical properties comparable with a wide diameter implant.     

Evaluation of primary stability in modified implants: Analysis by resonance frequency and insertion torque

Background

Changes in the macrogeometry of dental implants are known to influence primary stability and the osseointegration process.

Purpose

The purpose of the present in vitro study was to evaluate the mechanical behavior of geometric changes in the apex region of dental implants.

Methods

Thirty‐five cylindrical dental implants (Titamax Ti; Neodent) were machined at the apical third to reproduce the experimental groups: without apical cut (Wc), apical bi‐split cut, apical tri‐split cut, apical quadri‐split cut (Qs). One (control group) (Titamax Ti Ex) (n = 7) without any modifications was added. The implants had the same final dimensions (4.1 x 11 mm²). All implants were inserted into artificial bone blocks and were evaluated by insertion torque and resonance frequency by ISQ values (Osstell). Two‐tailed analysis of variance (One‐way ANOVA) and Tukey's post‐test (P < .05).

Results

Control and Qs implants showed a significant increase of the insertion torque (P < .001). For the resonance frequency, Wc and (control) implants had the greatest ISQ values. However, there's no significant difference between (control) and Qs for the ISQ values (P < .001).

Conclusion

Within the limitations of the present study, the proposed geometries at the apical third of dental implants greatly influenced its insertion torque and primary stability in vitro.     

Implant stability and histomorphometry: a correlation study in human cadavers using stepped cylinder implants

The aim of the present study was to determine the correlation between the primary stability of dental implants placed in edentulous maxillae and mandibles, the bone mineral density and different histomorphometric parameters. After assessing the bone mineral density of the implant sites by computed tomography, 48 stepped cylinder screw implants were installed in four unfixed human maxillae and mandibles of recently deceased people who had bequeathed their bodies to the Anatomic Institute I of the University of Erlangen-Nuremberg for medical-scientific research. Peak insertion torque, Periotest values and resonance frequency analysis were assessed. Subsequently, histologic specimens were prepared, and bone-to-implant contact, the trabecular bone pattern factor (TBPf), the density of trabecular bone (BV/TV) and the height of the cortical passage of the implants were determined. The correlation between the different parameters was calculated statistically. The mean resonance frequency analysis values (maxilla 6130.4+/-363.2 Hz, mandible 6424.5+/-236.2 Hz) did not correlate with the Periotest measurements (maxilla 13.1+/-7.2, mandible -7.9+/-2.1) and peak insertion torque values (maxilla 23.8+/-2.2 N cm, mandible 45.0+/-7.9 N cm) (P=0.280 and 0.193, respectively). Again, no correlations could be found between the resonance frequency analysis, the bone mineral density (maxilla 259.2+/-124.8 mg/cm(3), mandible 349.8+/-113.3 mg/cm3), BV/TV (maxilla 19.7+/-8.8%, mandible 34.3+/-6.0%) and the TBPf (maxilla 2.39+/-1.46 mm-1, mandible -0.84+/-3.27 mm-1) (P=0.140 and 0.602, respectively). However, the resonance frequency analysis values did correlate with bone-to-implant contact of the oral aspect of the specimens (maxilla 12.6+/-6.0%, mandible 35.1+/-5.1%) and with the height of the crestal cortical bone penetrated by the implants in the oral aspect of the implant sites (maxilla 2.1+/-0.7 mm, mandible 5.1+/-3.7 mm) (P=0.024 and 0.002, respectively). The Periotest values showed a correlation with the height of the crestal cortical bone penetrated by the implants in the buccal aspect of the implant sites (maxilla 2.5+/-1.2 mm, mandible 5.4+/-1.2 mm) (P=0.015). The resonance frequency analysis revealed more correlations to the histomorphometric parameters than the Periotest measurements. However, it seems that the noninvasive determination of implant stability has to be improved in order to give a more comprehensive prediction of the bone characteristics of the implant site.     

Initial stability and bone strain evaluation of the immediately loaded dental implant: an in vitro model study

Objectives: The aim of this study was to evaluate the effects of cortical bone thickness and trabecular bone elastic modulus on the strain in the bone surrounding an immediately loaded implant. We also examined the correlations between bone structure and the following indices of primary implant stability: insertion torque value (ITV), Periotest value (PTV), and implant stability quotient (ISQ). Material and methods: The ITV, PTV, and ISQ were measured in 24 artificial jaw bone models representing cortical bone with four thicknesses (0, 1, 2, and 3 mm) and trabecular bone with four elastic moduli (137, 47.5, 23, and 12.4 MPa). Two loading conditions were applied (force of 130 N applied vertically and at 45° laterally), and the strains in the crestal region were measured by rosette strain gauges with a data acquisition system. Results: When the cortical bone thickness and the elastic modulus of trabecular bone decreased, the bone strains increased by 10.3–52.1% and 39–73.1%, respectively, for vertical loading and by 35–62% and 42.4–56.2% for lateral loading. The cortical bone thickness has a stronger correlation (R²=0.95–0.71) with ITV, PTV, and ISQ than the elastic modulus of trabecular bone (R²=0.89–0.59). Conclusions: The initial stability at the time of implant placement is influenced by both the cortical bone thickness and the elastic modulus of trabecular bone; however, these parameters are not totally linearly correlated with ITV, PTV, and ISQ. The placement of an immediately loaded implant in cases with thin cortical bone and/or weak trabecular bone can induce extreme bone strains and may increase the risk of implant failure. To cite this article:
Huang H‐L, Chang Y‐Y, Lin D‐J, Li Y‐F, Chen K‐T, Hsu J‐T. Initial stability and bone strain evaluation of the immediately loaded dental implant: an in vitro model study.
Clin. Oral Impl. Res. 22 , 2011; 691–698
doi: 10.1111/j.1600‐0501.2010.01983.x     

The relationship between implant stability quotient values and implant insertion variables: a clinical study

Summary The aim of this study was to determine whether resonance frequency analysis can be integrated into the routine clinical evaluation of the initial healing of dental implants. In addition, this study was designed to verify whether there was a correlation between implant stability quotient (ISQ) values, maximum insertion torque values, angular momentum and energy, and to evaluate the importance of different clinical factors in the determination of ISQ values and maximum insertion torque values at implant insertion. Two different implant designs of 81 dental implants in 41 patients were evaluated using ISQ values. Maximum insertion torque values were obtained during the placement procedure. Two new methods were used to calculate the angular momentum developed due to implant installation as well as the energy absorbed by the bone. A linear correlation between ISQ values and maximum insertion torque values at the initial implant surgery was found (P < 0·01). There was a correlation between ISQ values and angular momentum (P < 0·05), although ISQ values and energy did not show a significant linear correlation at the initial surgery (P > 0·05). There was a correlation between maximum insertion torque values, each part’s angular momentum, and their energies during installation (P < 0·01). The sequence of the variables that influenced ISQ values was implant location, design, diameter, and gender of the patient. The results of this experiment suggest that both ISQ values and new methods to calculate angular momentum and energy can help to predict implant stability.     

Relationship between the bone density estimated by cone-beam computed tomography and the primary stability of dental implants

Objectives: The aims of this study were to objectively assess bone quality with density values obtained by cone‐beam computed tomography (CBCT) and to determine the correlations between bone density and primary stability of dental implants. Material and methods: Eighteen Straumann implants were inserted into 18 fresh femoral heads of swine. The bone densities of implant recipient sites were preoperatively determined by the density value using CBCT. The maximum insertion torque value of each implant was recorded using a digital torque meter. Resonance frequency, which represented a quantitative unit called the implant stability quotient (ISQ), was measured using an Osstell^® Mentor immediately after the implant placement. Spearman's correlation coefficient was calculated to evaluate the correlations among density values, insertion torques, and ISQs at implant placement. Results: The density values ranged from 98 to 902. The mean density value, insertion torque, and ISQ were 591±226, 13.4±5.2 Ncm, and 67.1±8.1, respectively. Statistically significant correlations were found between the density values and insertion torque (r_s=0.796, P<0.001), density values and ISQ (r_s=0.529, P=0.024), and insertion torque and ISQ (r_s=0.758, P<0.001). Conclusions: The bone quality evaluated by specific CBCT showed a high correlation with the primary stability of the implants. Hence, preoperative density value estimations by CBCT may allow clinicians to predict implant stability. Whether the density values obtained by the CBCT device used in the present study could be applied to other devices requires further elucidation. To cite this article:
Isoda K, Ayukawa Y, Tsukiyama Y, Sogo M, Matsushita Y, Koyano K. Relationship between the bone density estimated by cone‐beam computed tomography and the primary stability of dental implants.
Clin. Oral Impl. Res. 23 , 2012; 832–836
doi: 10.1111/j.1600‐0501.2011.02203.x     

种植初期稳定性的意义及其参数标准

通过文献复习,梳理明确种植初期稳定性的性质、意义、测试、参数以及影响因素.种植初期稳定性即种植体-骨界面的锚固力,是一种纯粹的机械现象,其意义在于维持种植体静立不动状态,使新骨不受干扰地生长附着在种植体表面,避免纤维组织生长,最终达到骨整合.临床比较常见的初期稳定性测试方法有植入扭力(insertion torque,...     

Clinical study on the insertion torque and wireless resonance frequency analysis in the assessment of torque capacity and stability of self-tapping dental implants

Summary  Resonance frequency (RF) analysis is a non-invasive, objective and sensitive technique developed for implantology where it measures the stability of the implant in osteotomy site. Although many studies were performed by the previous electronic version of RF analyzer, a very limited number of studies were carried out with the new magnetic wireless version. The aim of the study was to evaluate the relation between insertion torques, primary and secondary stability of self-tapping tapered implant systems. Thirteen subjects were treated with 42 endosseous implants using two-stage surgical procedure. The maximal insertion torque values were recorded prior to RF analysis during surgery. Six months after surgery, the secondary stability values were measured by the RF analysis. The average maximal insertion torque and primary and secondary magnetic RF values were 33 ± 11 N cm and 66 ± 12 ISQ and 71·9 ± 6 ISQ for 42 implants respectively. The correlation between insertion torque and RF values were indicated to be statistically significant ( P  < 0·01). Significantly higher maximal insertion torque, and primary and secondary magnetic RF values were achieved in mandibular sites compared with maxillary areas ( P  < 0·01). No significant differences were measured for all parameters when both systems were compared with each other ( P  > 0·05). There was a strong correlation between the insertion torque, primary and secondary magnetic RF values of self-tapping tapered endosseous implant used. Further studies are needed to understand the impact of the wireless magnetic RF analysis technique in clinics.     

Implant stability during osseointegration in irradiated and non-irradiated minipig alveolar bone: an experimental study

Objectives: Primary implant stability is related to local bone density. After insertion of an implant, implant stability is subject to changes due to bone remodeling. In patients who have undergone radiotherapy in the head and neck region, implant stability is impaired because irradiation reduces bone vitality. The current study was designed to monitor and test implant stability immediately after implant placement and during osseointegration in irradiated and non‐irradiated minipig alveolar bone. Materials and methods: All maxillary and mandibular premolars and molars of six adult Göttingen minipigs were extracted. The maxilla and mandible of three minipigs received three irradiation exposures at a total dose of 24 Gy. After irradiation, five initial implant holes were drilled in the residual alveolar ridge of each edentulous site. In order to assess bone vascularity, laser Doppler flowmetry recordings were carried out in the initial holes. A total of 120 implants were placed in the six minipigs. Subsequently, and at 8, 16, and 24 weeks after implant placement, implant stability was recorded by resonance frequency analysis (RFA). RFA values were expressed as an implant stability quotient (ISQ). Results: ISQ values recorded immediately after implant placement showed no differences between irradiated and non‐irradiated minipigs. Repeated measurements at the four recording moments showed a decrease of ISQ values in all minipigs, being more pronounced in irradiated bone, when compared with non‐irradiated bone. The results at the third and fourth recording moments showed a stabilization or even a slight increase of ISQ values. Conclusions: The results document the negative effect of irradiation on bone vascularity and hence on implant stability.     

Clinical study on the primary stability of two dental implant systems with resonance frequency analysis

Primary stability has a major impact on the long-term success of dental implants. The aim of this study was to investigate the correlation of resonance frequency analysis (RFA) and insertion torque of self-tapping and non-self-tapping implants and their respective differences in primary stability. A group of 263 patients were treated with a total of 602 conically formed dental implants: 408 non-self-tapping Ankylos and 194 self-tapping Camlog. The maximum insertion torque during implant placement was recorded. Resonance frequency, measured as the implant stability quotient (ISQ), was assessed once immediately after insertion and twice 3 months later. Torque values of the non-self-tapping implants were significantly higher than those in the self-tapping group (p = 0.023). RFA did not show differences between the 2 groups (p = 0.956), but a correlation between ISQ values after implantation and 3 months after implant placement was measured (r = 0.712). Within the implant systems, no correlation between insertion torque and resonance frequency values could be determined (r = 0.305). Our study indicates that the ISQ values obtained from different implant systems are not comparable. The RFA does not appear suitable for the evaluation of implant stability when used as a single method. Higher insertion torque of the non-self-tapping implants appeared to confirm higher clinical primary stability.