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     

Assessment of correlation between computerized tomography values of the bone, and maximum torque and resonance frequency values at dental implant placement

summary The aim of this study was to determine the bone density in the designated implant sites using computerized tomography (CT), the fastening torque values of dental implants, and the implant stability values using resonance frequency analysis. Further aim was to evaluate a possible correlation between bone density, fastening torque and implant stability. Eighty‐five patients were treated with 158 Brånemark System implants. CT machine was used for preoperative evaluation of the jawbone for each patient, and bone densities were recorded in Hounsfield units (HU). The fastening torque values of all implants were recorded with the OsseoCare equipment. Implant stability measurements were performed with the Osstell machine. The average bone density and fastening torque values were 751·4 ± 256 HU and 39·7 ± 7 Ncm for 158 implants. The average primary implant stability was 73·2 ± 6 ISQ for seventy implants. Strong correlations were observed between the bone density, fastening torque and implant stability values of Brånemark System TiUnite MKIII implants at implant placement (P < 0·001). These results strengthen the hypothesis that it may be possible to predict and quantify initial implant stability and bone quality from pre‐surgical CT diagnosis.     

Sensitivity of resonance frequency analysis method to assess implant stability

The aim of this human cadaver study was to determine the correlation between bone quality and implant stability parameters, and the relationship between resonance frequency value and peri-implant bone loss. Thirty-two implants were placed into four human cadaver mandibles. The bone density of the implant recipient site was determined using computerized tomography (CT) in Hounsfield units (HU). The peak insertion torque values were recorded. The resonance frequency (RF) measurements were performed immediately following implant insertion and also after one, two and three turns of the implant in a counterclockwise direction, representing peri-implant bone loss. The mean bone density, insertion torque and RFA values of all implants were 152 +/- 264 HU, 41.7 +/- 6 Ncm and 69.7 +/- 9 ISQ. Statistically significant correlations were found between bone density and insertion torque values, bone density and ISQ values, and insertion torque and ISQ values. A significant influence of the peri-implant bone loss on ISQ value was also observed. The findings from this study illustrate significant correlation between bone density and implant stability parameters, and a linear relationship between peri-implant bone levels and resonance frequency value.     

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.     

Implant stability and bone density: assessment of correlation in fresh cadavers using conventional and osteotome implant sockets

Objective: To compare the primary stability of implants placed in conventional and osteotome sites and to evaluate the level of correlation between cutting torque measurements, resonance frequency analysis (RFA), and bone density. Materials and methods: Eight human femoral heads were scanned with computed tomography for bone density measurements as Hounsfield units (HU), and individualized computed tomography‐based surgical stents were prepared for placement of implants. Five implant sockets were prepared in each collum (CoF), caput (CaF), and trochanter (Tr‐MM) section of the femoral heads using the conventional drilling technique or by a combination of drilling and use of an osteotome. Cutting‐torque values (CTV) of the implants were measured by a manual torque wrench, followed by determination of implant stability quotients (ISQ) by RFA. Results: The CTVs of implants were similar in the conventional group, but different in the osteotome group (P<0.05). There was a general tendency toward achieving higher CTV and ISQ values in CoF than CaF and Tr‐MM (P<0.05), and measurements in CaF and Tr‐MM were comparable (P>0.05). The mean HU of sites were similar, although CoF had higher HU values (P>0.05). CTV of implants in CaF and Tr‐MM and ISQ values in CoF in the conventional groups were higher than those in the osteotome groups (P<0.05). The correlation between CTV and HU in Tr‐MM was significant in the osteotome group, although no other correlations between CTV, ISQ, and HU could be detected (P>0.025). Conclusions: Conventional placement led to higher implant stability than the drilling and osteotome technique used in the study. No correlation could be found between CTV, RFA, and bone density.     

Influence of factors related to implant stability detected by wireless resonance frequency analysis device

Summary Resonance frequency analysis (RFA) was introduced as a method for measuring implant stability more than a decade ago. Implant stability quotient (ISQ) values obtained using a recently introduced wireless RFA device have made it possible to evaluate stability in a non‐invasive technique; however, there are few studies of the factors that affect ISQ values determined using this device. The aim of the present study was to evaluate the association between ISQ values determined by wireless RFA and various factors related to dental implant stability using a pig cortical bone model. Dental implants (Replace^® Select Tapered implants) with a length of 10 mm were placed into pig cortical bone samples, then, ISQ values were determined using wireless RFA under various conditions (probe orientation, diameter of implant, insertion torque and peri‐implant bone loss). The results of this study showed that ISQ values were not affected by the direction of the probe from parallel to perpendicular to the long axis of the pig bone or to the smart peg. In addition, the diameter of the implant did not have a significant effect on the measured ISQ values. Statistically significant correlations were found between insertion torque and ISQ values (Spearman’s test, P < 0·05), and lower ISQ values were observed for deeper peri‐implant vertical defects (Mann–Whitney U‐test, P < 0·05). A wireless RFA device appears to be useful for measuring implant stability within the limits of the present in vitro study.     

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.     

后牙区骨密度对种植体骨结合稳定性的影响

目的应用锥束CT三维重建影像技术对后牙种植区骨密度进行定量测量,同时结合OS—STEL种植体稳定系数（ISQ）,分析表示骨密度的豪森菲尔德单位（HU）值及种植体稳定系数（ISQ）值对植入种植体稳定性的影响。方法对32名（男14人,女18人）后牙种植修复患者的49枚种植体进行术前测量种受植部位HU值,记录植入最大扭矩（Ncm）,在种植初期及5个月后进行共振频率分析（RFA）。结果49枚后牙区种植体全部存留;植入区HU值：477．76±129．88;植入时最大扭矩：35．82±10．275;初期ISQ：77．55±6．84;骨结合后ISQ：78．78±6．25。植人最大扭矩与初期ISQ（P=0．851）、植入区HU值与初期ISQ（P=0．721）未检出相关性,而植入区HU值与骨结合后ISQ值则有显著相关性（P〈0．01）。结论骨密度与种植体骨结合后稳定性密切相关,骨密度HU值越高,预后的种植体稳定性越高。     

Role of Clinician's Experience and Implant Design on Implant Stability. An Ex Vivo Study in Artificial Soft Bones

Objectives: Clinical experience in implant placement is important in order to prevent implant failures. However, the implant design affects the primary implant stability (PS) especially in poor quality bones. Therefore, the aim of this study was to compare the effect of clinician surgical experience on PS, when placing different type of implant designs. Methods: A total of 180 implants (90 parallel walled‐P and 90 tapered‐T) were placed in freshly slaughtered cow ribs. Bone quality was evaluated by two examiners during surgery and considered as ‘type IV’ bone. Implants (ø 5 mm, length: 15 mm, Osseotite, BIOMET 3i, Palm Beach Gardens, FL, USA) were placed by three different clinicians (master/I, good/II, non‐experienced/III, under direct supervision of a manufacturer representative; 30 implants/group). An independent observer assessed the accuracy of placement by resonance frequency analysis (RFA) with implant stability quotient (ISQ) values. Two‐way analysis of variance (ANOVA) and Tukey's post hoc test were used to detect the surgical experience of the clinicians and their interaction and effects of implant design on the PS. Results: All implants were mechanically stable. The mean ISQ values were: 49.57(± 18.49) for the P‐implants and 67.07(± 8.79) for the T‐implants. The two‐way ANOVA showed significant effects of implant design (p < .0001), clinician (p < .0001), and their interaction (p < .0001). The Tukey's multiple comparison test showed significant differences in RFA for the clinician group I/II (p = .015) and highly significant (p < .0001) between I/III and II/III. The P‐implants presented (for I, II, and III) mean ISQ values 31.25/49.18/68.17 and the T‐implants showed higher ISQ values, 70.15/62.08/68.98, respectively. Clinicians I and II did not show extreme differences for T‐implants (p = .016). In contrast, clinician III achieved high ISQ values using P‐ and T‐implants following the exact surgical protocol based on the manufacturer guidelines. T‐implants provided high stability for experienced clinicians compared with P‐implants. Conclusion: T‐implants achieved greater PS than the P‐implants. All clinicians consistently achieved PS; however, experienced clinicians achieved higher ISQ values with T‐implants in poor quality bone.     

Is there a lower threshold value of bone density for early loading protocols of dental implants?

This clinical study aimed to determine the bone density in dental implant recipient sites using computerized tomography (CT) and to establish a lower threshold value of bone density for early loading protocols. The study group was composed of 100 early loaded implants in 42 patients. A total of four groups were established according to the loading time and implant sites. The bone density of each recipient site for implant placement was determined using CT. The maximum insertion torque values were recorded with torque controlling machine. Implant stability measurements were performed with resonance frequency analyser. The bone density values varied from 528 to 1231 HU. It was found that mean bone density, insertion torque and resonance frequency analysis values were 887 +/- 180 HU, 41.2 +/- 6 Ncm, and 73.7 +/- 4 ISQ, respectively. Strong correlations were found between these three parameters. CT may be a useful tool for assessing the bone density of recipient areas before implant placement, and the early loading of dental implants may be possible in the implant sites where bone density is over 528 HU.     

Influence of cortical bone anchorage on the primary stability of dental implants

Purpose

This retrospective chart review study assessed patient records to determine implant insertion torque (IT) and implant stability quotient (ISQ) values during implant placement to evaluate the correlation with cortical bone anchorage (mono- or bicortical).

Methods

Primary stability data (IT during implant placement surgery and ISQ values immediately after implant placement) and cone beam computed tomography of 33 patients (165 implants) were assessed. Patients were divided into the following groups: G1, implants with apical cortical bone contact; G2, implants with bicortical bone contact (apical and cervical regions); and G3, implants with cervical cortical bone contact.

Results

Sixty-eight implants were excluded due to cortical bone contact on regions other than implant apical or cervical. Ninety-seven implants were therefore assessed for this study. No implant failure was found after a mean 70.42-month follow-up time. Implants with bicortical anchorage (G2) showed higher IT (64.1 Ncm) during implant placement and higher ISQ values (76) (p?<?0.05). Monocortical implants (G1, apical, and G3, cervical) showed similar IT (G1 52.3 and G3 54.3) and ISQ values (G1 71.9 and G3 73) (p?>?0.05). No correlation (Pearson correlation coefficient) was found between the two stability measurement devices for the different cortical bone anchorages that were analyzed (G1 0.190, G2 0.039, and G3 ??0.027) (p?>?0.05).

Conclusions

Insertion torque values and implant stability quotients were influenced by cortical bone contact. No significant correlation was found between IT and ISQ values—higher insertion torque values do not necessarily lead to higher implant stability quotients.

     

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.     

A comparison between insertion torque and resonance frequency in the assessment of torque capacity and primary stability of Brånemark system implants

summary The aim of this study was to determine primary stability and insertion torque of Brånemark System implants placed in the anterior mandible, and to evaluate a possible correlation between primary stability and insertion torque. Thirty edentulous patients were treated with 60 Brånemark System implants using a one‐stage technique. The insertion torque values of all implants were recorded with the Osseocare equipment. Immediately after implant placement, each implant was connected to the transducer of an Osstell machine to measure the primary implant stability. The average insertion torque and resonance frequency values were 41·5 ± 5·8 and 74·1 ± 3·8 for 30 implants. The correlation between insertion torque and resonance frequency values indicated a statistical significance (P < 0·001). The difference between mean insertion torque values for female and male patients was statistically significant (P < 0·001). No significant difference (P > 0·05) was found between younger and older patients with mean insertion torque values of 43·1 ± 4·7 and 40·1 ± 6·5 respectively. The results of this study showed a strong correlation between the primary stability and insertion torque values of Brånemark System TiUnite MKIII implants at the time of implant placement.     

Primary stability and self-tapping blades: biomechanical assessment of dental implants in medium-density bone

Aim: The aim of this biomechanical study was to assess the influence of self‐tapping blades in terms of primary implant stability between implants with self‐tapping blades and implants without self‐tapping blades using five different analytic methods, especially in medium‐density bone. Materials and methods: Two different types of dental implants (4 × 10 mm) were tested: self‐tapping and non‐self‐tapping. The fixture design including thread profiles was exactly the same between the two groups; the only difference was the presence of cutting blades on one half of the apical portion of the implant body. Solid rigid polyurethane blocks with corresponding densities were selected to simulate medium‐density bone. Five mechanical assessments (insertion torque, resonance frequency analysis [RFA], reverse torque, pull‐out and push in test) were performed for primary stability. Results: Implants without self‐tapping blades showed significantly higher values (P<0.001) in four biomechanical assessments, except RFA (P=0.684). However, a statistically significant correlation could not be detected between insertion torque values with the four different outcome variables (P>0.05). Conclusions: The outcomes of the present study indicate that the implant body design without self‐tapping blades has a good primary stability compared with that with self‐tapping blades in medium‐density bone. Considering the RFA, a distinct layer of cortical bone on marginal bone will yield implant stability quotient values similar to those in medium‐bone density when implants have the same diameter. To cite this article:
Kim Y‐S, Lim Y‐J. Primary stability and self‐tapping blades: biomechanical assessment of dental implants in medium‐density bone.
Clin. Oral Impl. Res. 22 , 2011; 1179–1184.
doi: 10.1111/j.1600‐0501.2010.02089.x     

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.     

Does bone mineral density influence the primary stability of dental implants? A systematic review

Objective: The aim of this systematic review was to investigate the influence of bone mineral density on the primary stability of dental implants. Material and methods: A search of health science databases (Cochrane Library, MEDLINE‐PubMed, ISI Web of Knowledge, EMBASE, LILACS) and grey literature was performed, including papers published until January 2011. The main key words used were “bone density” (MeSH/DeCS), “dental implant” (MeSH/DeCS), “implant stability”, “implant stability quotient”, “ISQ”, “resonance frequency analysis”, “RFA”, “Osstell”, “Periotest value”, “PTV”, “Periostest”, “insertion torque”, “placement torque”, “cutting torque”. The inclusion criteria comprised observational clinical studies performed in patients who received dental implants for rehabilitation; studies that evaluated the association between bone mineral density and implant primary stability; bone density assessment performed by measurement of Hounsfield units using cone beam computed tomography; and dental implant primary stability evaluated by ISQ value, PTV value or insertion torque measurement. The articles selected were carefully read and classified as low, moderate and high methodological quality, and data of interest were tabulated. Results: Ten articles met the inclusion criteria, but only seven were included because of overlapping patients. They were classified as low or moderate methodological quality and control of bias, and presented positive association between primary stability and bone density. Conclusions: There is a positive association between implant primary stability and bone mineral density of the receptor site. However, the methodological quality and control of bias of the studies should be improved to produce stronger evidences. To cite this article:
Marquezan M, Osório A, Sant'Anna E, Souza MM, Maia L, Does bone mineral density influence the primary stability of dental implants? A systematic review.
Clin. Oral Impl. Res. 23 , 2012; 767–774.
doi: 10.1111/j.1600‐0501.2011.02228.x     

Predicting primary stability of orthodontic mini‐implants,according to position,screw‐size,and bone quality,in the maxilla of aged patients: a cadaveric study

This study aimed to evaluate the effect of implant size and bone condition on primary stability of orthodontic mini‐implants with a view to predict the primary stability before insertion. Four‐hundred and forty mini‐implants of two different diameters (2.0 and 2.3 mm) and lengths (7 and 12 mm) were inserted at 11 different positions in human cadaver maxillae. Before placement of mini‐implants, cone beam computed tomography (CBCT) scans were performed to measure bone density and cortical thickness and, after mini‐implant placement, implant stability quotient (ISQ) values were determined by resonance frequency analysis and cofactors were analyzed to determine their influence on the primary stability. Additionally, an equation was developed to predict the expected stability based on implant size and bone quality. Bone density varied between 433 (SD 122) and 587 (SD 249) Hounsfield units (HU), and cortical thickness varied between 0.49 (SD 0.42) and 0.98 (SD 0.60) mm. The lowest ISQ value, of 15.50 (SD 7.29) (bone density: 531 (SD 219) HU; cortical thickness: 0.65 (SD 0.58) mm), was found for a mini‐implant of 2.0 × 7 mm and the highest ISQ value, of 46.30 (SD 8.69) (bone density: 587 (SD 249) HU; cortical thickness: 0.98 (SD 0.60) mm), was found for a mini‐implant of 2.3 × 11 mm. Statistically significant influences of the cofactors on primary stability were demonstrated. To visualize the predictive power of the model, the observed values versus the predicted values of primary stability were compared and the model fit was represented by residual plots. The expected primary stability can be estimated by a linear regression model comprising the radiologically determined bone density, cortical thickness, implant length and diameter, and placement position.     

Comparison of implant stability by means of resonance frequency analysis for flapless and conventionally inserted implants

Background: Resonance frequency analysis (RFA) is a noninvasive technique for the quantitative assessment of implant stability. Information on the implant stability quotient (ISQ) of transmucosally inserted implants is limited. Purpose: The aim of this investigation was to compare the ISQ of conventionally inserted implants by raising a muco‐periostal flap with implants inserted using a flapless procedure. Materials and Methods: Forty elderly patients with complete edentulous maxilla were consecutively admitted for treatment with implant‐supported prostheses. A computer tomography was obtained for the computer‐assisted implant planning. One hundred ten implants were placed conventionally in 23 patients (flap‐group) and 85 implants in 17 patients by means of the flapless method (flapless‐group) using a stereolithographic template. RFA measurements were performed after implant placement (baseline) and after a healing time of 12 weeks (reentry). Results: All implants exhibited clinically and radiographically successful osseointegration. Bone level did not change significantly neither for genders nor type of surgical protocol. Mean ISQ values of the flapless‐group were significantly higher at baseline (p < .001) and at reentry (p < .001) compared with the flap‐group. The ISQ values were significantly lower at reentry compared with baseline for the flap‐group (p = .028) but not for the flapless‐group. This group showed a moderate, but insignificant increase. RFA measurements of males resulted in ISQ values that were thoroughly higher as compared with females at both time‐points in both groups. Correlation between RFA and bone level was not found. Conclusions: The flapless procedure showed favorable conditions with regard to implant stability and crestal bone level. Some changes of the ISQ values that represent primary (mechanical) and secondary (bone remodeling) implant stability were observed in slight favor of the flapless method and male patients. In properly planned and well‐selected cases, the minimal invasive transmucosal technique using a drill‐guide is a safe procedure.     

In Vitro Assessment of Primary Stability of Straumann® Implant Designs

Background: Primary implant stability (PS) is one of the main factors influencing implant survival rate. Several methods to determine the PS have been used, such as Periotest values (PVs) and resonance frequency analysis (RFA) with implant stability quotient (ISQ) values. Purpose: The aim of this study was to compare different implant designs in regard to PS assessed by Periotest and RFA in vitro. Materials and Methods: A total of 90 implants were placed in freshly slaughtered cow ribs. The implants (Straumann®, Institute Straumann AG, Basel, Switzerland; length 10 mm, ø3.3 mm) had the following three designs: Bone Level (BL, 30 implants), Standard Plus (SP, 30 implants), and Tapered Effect (TE, 30 implants). Before implant placement, the investigator was calibrated for every design according to the manufacturer's instructions. An independent observer, blinded to the study, assessed the accuracy of placement. RFA based on the Osstell device and PVs were performed after abutment connection. One‐way analysis of variance and Tukey's post hoc test were used for statistical evaluation. Results: All implants were mechanically stable. The mean PV for BL was ?4.67(± 1.18), for SP, ?6.07(± 0.94), and for TE, ?6.57(± 0.57). The mean ISQ values were 75.02(± 3.65), 75.98(± 3.00), and 79.83(± 1.85), respectively. The one‐way ANOVA showed significant difference among three implant designs in PV (p < .0001) and for the ISQ between BL/TE or SP/TE implants (p < .0001). In addition, the Tukey's (pair‐wise comparison) test showed significant differences in PV and RFA between the BL/TE (p < .0001). Conclusion: Within the limitations of this study, higher implant stability was found for tapered designed implants.     

Factors influencing resonance frequency analysis assessed by Osstell™mentor during implant tissue integration: I. Instrument positioning,bone structure,implant length

Aim: To monitor longitudinally the development of implant stability of SLA Straumann^® tissue‐level implants using resonance frequency analysis (RFA) and to determine the influence of instrument positioning, bone structure and implant length on the assessment of RFA. Material and methods: Thirty‐two healthy adult patients received either 8 mm, ?4.1 mm Straumann^® Standard Plus tissue‐level implants (n=16: Group A) or 10 mm, ?4.1 mm Straumann^® Standard Plus tissue‐level implants (n=16: Group B). During healing, RFA was performed on Weeks 0,1, 2, 3, 4, 5, 6, 8 and 12. The implants were restored after 10 weeks (impression taking) and 12 weeks. In addition, probing depth, presence of plaque and bleeding on probing were assessed. Implant stability quotient (ISQ) values of Groups A and B were compared using unpaired t‐tests and longitudinally applying paired t‐tests between Week 0 and the subsequent time points. Results: Positioning of the Osstell^?mentor device did not affect the ISQ values. Generally, ISQ values increased continuously during healing from a mean of 65.1 (SD 16.97) to 74.7 (SD 5.17) (significantly from Week 0 to Weeks 6, 8 and 12). Lower bone density (Type III or IV) resulted in significantly lower ISQ values up to Week 8. Implant length affected the increase in ISQ values over time. While no significant increase was observed with 10 mm implants, ISQ values of 8 mm implants increased significantly from Week 0 to Weeks 6, 8 and 12. Conclusions: Using Osstell^?mentor, ISQ values are reproducible irrespective of instrument positioning. ISQ values are affected by the bone structure and implant length. Hence, no predictive values can be attributed to implant stability. To cite this article:
Sim CPC, Lang NP. Factors influencing resonance frequency analysis assessed by Osstell^?mentor during implant tissue integration: I. Instrument positioning, bone structure, implant length.
Clin. Oral Impl. Res. 21 , 2010; 598–604.
doi: 10.1111/j.1600‐0501.2009.01878.x