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.     

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.     

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,...     

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     

Biomechanical aspects of primary implant stability: a human cadaver study

Background: The quality of bone is an important factor in the successful implant treatment, and it is evident that higher implant failure is more likely in poor quality of bone. The primary stability of oral implants related to resistance to micromotion during healing is influenced by bone quality, surgical technique, and implant design.
Purposes: The aims of this biomechanical study were to explore the effect of bone quality on initial intraosseous stability of implants, and to determine the correlations between the bone quality and implant stability parameters.
Materials and Methods: Twenty-four implants (Neoss Ltd., Mölnlycke, Sweden) were placed into anterior and posterior regions of three human cadaver mandibles. The bone densities of implant recipient sites were preoperatively determined using computerized tomography (CT) in Hounsfield unit (HU). The maximum insertion torque values were recorded, and primary implant stability measurements were noninvasively performed by means of resonance frequency analysis (RFA).
Results: The bone density values ranged from −267 HU to 553 HU. It was found that mean bone density, insertion torque, and RFA values were 113 ± 270 HU, 41.9 ± 5 Ncm, and 70 ± 7 implant stability quotient (ISQ), respectively. Statistically significant correlations were found between bone density and insertion torque values ( r  = 0.690, p  < .001); bone density and ISQ values ( r  = 0.557, p  < .05); and insertion torque and ISQ values ( r  = 0.853, p  < .001).
Conclusion: CT is a useful tool to assess bone quantity and quality in implant recipient sites, and bone density has a prevailing effect on implant stability at placement.     

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     

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.     

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。     

Influence of bony defects on implant stability

Introduction: The purpose of this study was to analyze the evolution of implant mechanical stability in different types/sizes of bony defects using both Periotest and Osstell devices as “objective tools.” Materials and methods: Thirty‐two implants were randomly allocated to one of the four types of bone defects: marginal bone loss, peri‐apical bone defect, constant width dehiscence and constant length dehiscences. Periotest/Osstell measurements were completed before and during staged bone removal (to enlarge defect size). Results: Significant differences (P<0.05) with initial values were found after a 2 mm marginal bone removal (Osstell/Periotest); for a peri‐apical bone lesion, after removal of 5 mm (Osstell) or 8 mm (Periotest); for a 6‐mm‐long dehiscence, after removal up to 180° of the implant perimeter (Osstell/Periotest); for a 3‐mm‐wide dehiscence, after removal of 10 mm (Osstell) or 6 mm (Periotest). Conclusion: Periotest and Osstell are in general not very sensitive in the identification of peri‐implant bone destruction, except for marginal bone loss. To cite this article:
Merheb J, Coucke W, Jacobs R, Naert I, Quirynen M. Influence of bony defects on implant stability.
Clin. Oral Impl. Res. 21 , 2010; 919–923.
doi: 10.1111/j.1600‐0501.2010.01932.x     

Correlating implant stability to bone structure

Objectives: The aim of this study was to demonstrate a possible correlation between bone microarchitecture and primary implant stability.
Material and methods: Twenty-two implants (Ankylos^® and Straumann^®) were inserted into the maxillae and mandibles of human cadavers. Bone structure was determined by computed tomography in three specimens (male, age 53; female, 67; female, 80). A strict clinical protocol was used for implantation. Primary implant stability was measured by resonance frequency analysis (Osstell Mentor). The bone structure was analyzed by micro-computed tomography (CT). Bone histomorphometrical parameters were calculated and correlated to primary implant stability.
Results: Implant stability quotients (ISQ) ranged from 50 to 70% depending on the specimens and sites. Histomorphometry indicated differences in the bone microstructures of the specimens. However, ISQ values were not related to trabecular bone histomorphometrical parameters. The sole correlation was found between ISQ values and cortical bone thickness.
Conclusion: This study confirms the relevance for primary stability of cortical thickness around implants. The thickness of cortical bone can be assessed using a standard clinical CT.     

Assessment of dental implant stability in osseodistraction-generated bone: a resonance frequency analysis

Objective: To determine the implant stability in osseodistraction-generated (ODG) bone after a 2-month consolidation period, assessed by resonance frequency analysis (RFA).
Material and methods: Twenty healthy, non-smoker female patients received 71 dental implants, 39 placed in native bone and 32 in ODG bone, after an 8-week consolidation period. Primary and secondary stability of the implants was assessed by means of the Osstell^® mentor device. The average value of six measurements was considered for the statistical analysis at each time point.
Results: The age of the patients who received implants in ODG was not significantly different from that of those receiving implants in pristine bone (48.0±10.9); [ X =1.6; 95% confidence interval (CI)=−7.7–10.9].
Although implants placed in both bone types indicated good primary stability, a statistically significant difference in favour of implants placed in pristine bone could be identified in terms of osteogenic distraction (OD) ( X _i− X _j=3.4; 95% CI=1.7–5.8). After a 1.5-month integration period, none of the implants failed, but implant stability still recorded higher values for implants located in the pristine bone ( X _i− X _j=2.5; 95% CI=0.5–4.4).
A positive linear correlation could be established between the implant stability quotient (ISQ) values at implant placement (primary stability) and the post-integration ISQ score (secondary stability) for both bone types, but only 16% of the post-integration ISQ in the ODG bone could be attributed to the primary stability.
Conclusions: Within the limitations of this study, OD bone offers – after a 2-month consolidation period – high primary and secondary stabilities after implant placement.     

The primary stability of two dental implant systems in low-density bone

Primary stability in low-density bone is crucial for the long-term success of implants. Tapered implants have shown particularly favourable properties under such conditions. The aim of this study was to compare the primary stability of tapered titanium and novel cylindrical zirconia dental implant systems in low-density bone. Fifty implants (25 tapered, 25 cylindrical) were placed in the anterior maxillary bone of cadavers meeting the criteria of low-density bone. The maximum insertion (ITV) and removal (RTV) torque values were recorded, and the implant stability quotients (ISQ) determined. To establish the isolated influence of cancellous bone on primary stability, the implantation procedure was performed in standardized low-density polyurethane foam bone blocks (cancellous bone model) using the same procedure. The primary stability parameters of both implant types showed significant positive correlations with bone density (Hounsfield units) and cortical thickness. In the cadaver, the cylindrical zirconia implants showed a significantly higher mean ISQ when compared to the tapered titanium implants (50.58 vs 37.26; P < 0.001). Pearson analysis showed significant positive correlations between ITV and ISQ (P = 0.016) and between RTV and ISQ (P = 0.035) for the cylindrical zirconia implants; no such correlations were observed for the tapered titanium implants. Within the limitations of this study, the results indicate that cylindrical zirconia implants represent a comparable viable treatment option to tapered titanium implants in terms of primary implant stability in low-density human bone.     

下颌后牙区骨组织与种植体初期稳定性的相关性研究

目的:研究下颌骨后牙区骨组织结构对种植体初期稳定性的影响。方法:20名患者术前拍摄CT,通过软件SimPlant测量得到种植体周围平均骨密度及种植体颈部骨皮质厚度。共植入24枚种植体,术中植入后即刻用Osstell仪器测量得到种植体稳定系数(ISQ)。所有数据通过SPSS 17软件包进行统计学分析(P<0.05)。结果:种植体颈部骨皮质厚度与ISQ相关(P<0.05),颌骨后牙区骨密度与ISQ无相关关系(P>0.05),性别、年龄与ISQ无相关关系(P>0.05)。结论:术前对下颌骨后牙区骨密度的测量不能预测种植体初期稳定性,种植体初期稳定性与种植体颈部骨皮质厚度相关;与种植体初期稳定性相关的因素还需进一步研究。     

Influence of implant diameter on surrounding bone

OBJECTIVES: Implant osseointegration is dependent upon various factors, such as bone quality and type of implant surface. It is also subject to adaptation in response to changes in bone metabolism or transmission of masticatory forces. Understanding of long-term physiologic adjustment is critical to prevention of potential loss of osseointegration, especially because excessive occlusal forces lead to failure. To address this issue, wide-diameter implants were introduced in part with the hope that greater total implant surface would offer mechanical resistance. Yet, there is little evidence that variation in diameter translates into a different bone response in the implant vicinity. Therefore, this study aimed at comparing the impact of implant diameter on surrounding bone. MATERIAL AND METHODS: Twenty standard (3.75 mm) and 20 wide (5 mm) implants were placed using an animal model. Histomorphometry was performed to establish initial bone density (IBD), bone to implant contact (BIC) and adjacent bone density (ABD). RESULTS: BIC was 71% and 73%, whereas ABD was 65% and 52%, for standard and wide implants, respectively. These differences were not statistically different (P>0.05). Correlation with IBD was then investigated. BIC was not correlated with IBD. ABD was not correlated to IBD for standard implants (r2=0.126), but it was correlated with wide implants (r2=0.82). In addition, a 1 : 1 ratio between IBD and ABD was found for wide implants. It can be concluded, within the limits of this study, that ABD may be influenced by implant diameter, perhaps due to differences in force dissipation.