Stability measurements of 1-stage implants in the edentulous mandible by means of resonance frequency analysis

OBJECTIVE: Resonance frequency analysis (RFA) is a method of measuring implant stability. However, little is known about RFA of implants with long loading periods. The objective of the present study was to determine standard implant stability quotients (ISQs) for clinical successfully osseointegrated 1-stage implants in the edentulous mandible. MATERIALS AND METHODS: Stability measurements by means of RFA were performed in regularly followed patients who had received 1- stage implants for overdenture support. The time interval between implant placement and measurement ranged from 1 year up to 10 years. The short-term group comprised patients who were followed up to 5 years, while the long-term group included patients with an observation time of > 5 years up to 10 years. For further comparison RFA measurements were performed in a matching group with unloaded implants at the end of the surgical procedure. For statistical analysis various parameters that might influence the ISQs of loaded implants were included, and a mixed-effects model applied (regression analysis, P <.0125). RESULTS: Ninety-four patients were available with a total of 205 loaded implants, and 16 patients with 36 implants immediately after the surgical procedure. The mean ISQ of all measured implants was 64.5 +/- 7.9 (range, 58 to 72). Statistical analysis did not reveal significant differences in the mean ISQ related to the observation time. The parameters with overall statistical significance were the diameter of the implants and changes in the attachment level. In the short-term group, the gender and the clinically measured attachment level had a significant effect. Implant diameter had a significant effect in the long-term group. CONCLUSIONS: A mean ISQ of 64.5 +/- 7.9 was found to be representative for stable asymptomatic interforaminal implants measured by the RFA instrument at any given time point. No significant differences in ISQ values were found between implants with different postsurgical time intervals. Implant diameter appears to influence the ISQ of interforaminal implants.     

Resonance frequency analysis in immediate loading of dental implants

Immediate loading of dental implants aims to shorten treatment time. Stability at implant insertion is critical to success. The aim of this prospective study is to compare primary implant stability, measured by insertion torque (IT) with resonance frequency analysis (RFA) expressed as ISQ. Patients requiring implant therapy were treated by teeth extractions, placement of 1-9 MIS implants, bone augmentation as needed and fixed provisional restorations. We measured IT and ISQ for non-submerged loaded (NSL), non-submerged non loaded (NSNL) and submerged (S) implants. 14 patients, aged 34-79 years, were recruited. 53 implants were inserted (38 maxillary & 15 mandibular). 30 implants, 18 in fresh extraction sites, were immediately loaded. ISQ was 63.3 +/- 2.8 (S.E.), 67.2 +/- 3.5 (S.E.) and 58.8 +/- 2.7 for the NSL, NSNL and S groups, respectively (p = 0.0459). IT was 40.4 +/- 1.8 Ncm, 46 +/- 4.0 and 35.3 +/- 2.1 (p = 0.0646). ISQ and IT were not statistically different between extraction vs. non-extraction and augmented vs. non-augmented sites. We found a significant difference in IT between maxillary & mandibular sites, and a significant correlation between ISQ & IT and between ISQ & implant diameter. These data suggest that ISQ is correlated to IT and is influenced mainly by implant diameter and not by implant length, location or bone level. Finally, a case including immediate implants, bone augmentation and immediate provisional restoration is presented.     

ITI种植体早期负重与传统负重稳定性的比较

目的：应用共振频率分析评价早期负重种植体的稳定性,为种植体早期负重的可行性提供客观依据。方法：50例牙列缺损患者共植入104颗ITISLA表面实心螺纹种植体,随机分为2组,实验组为早期负重组,于术后6周修复;对照组为无负重组,于术后12周修复。在种植体植入术后当天、1周、4周、6周、8周、12周使用无线共振频率分析仪（Osstell Mentor）测定2组种植体的稳定性,所得参数为种植体稳定值（ISO）。采用Minitab统计软件对数据进行t检验．得出各时段2组ISQ值的P值。结果：术后12周,2组种植体的留存率均为100％,2组种植体在各时间段的ISQ值均无显著差异（P〉0．05）,整体变化趋势相同：表现为初期稳定性均较高,于第1周至第4周下降,第6周逐步上升,其后稳定性基本保持不变或略有上升。随访期（修复后6个月）间,2组种植体的留存率均为100％。结论：ITISLA表面种植体早期负载是可行的。     

Resonance frequency analysis of stability on ITI implants with osteotome sinus floor elevation technique without grafting: a 5-month prospective study

Objective: The aim of the present study was to (1) monitor the stability changes of ITI implants placed in atrophic posterior maxillary ridges with osteotome sinus floor elevation (OSFE) without grafting during the first 5 months of healing utilizing resonance frequency analysis (RFA) and (2) determine the factors that affect the implant stability quotient (ISQ) at placement and healings. Material and methods: Forty‐two ITI implants were placed in the posterior maxilla in 32 patients with OSFE without bone grafting. The residual vertical bone height ranged from 4 to 8 mm (average 6.36 mm). Bone type was classified into one to four groups according to the Lekholm and Zarb index. ISQ was tested on the day of surgery and consecutively at 2, 4, 6, 8, 12, 16, and 20 weeks by RFA. Results: The 40 osseointegrated implants represented a survival rate of 95.2%. All the 40 implants achieved good primary stability and reached a comparably high stability at 16 weeks postoperation with a dip between 2 and 6 weeks in the stability curve. There was no significant difference of ISQ between type3 and type4 bone at implant placement and follow‐up. The mean ISQ and its changing pattern did not demonstrate a statistically significant difference according to the pretreatment vertical bone height and implant length. Conclusions: The findings of this study indicated that uneventful osseointegration may be predictable applying OSFE alone with no grafting in atrophic posterior maxilla. Residual bone height (RBH), implant length, and bone type did not seem to affect the implant stability in this clinical situation.     

Conventional and early loading of unsplinted ITI implants supporting mandibular overdentures

The aim of this study was to compare the success rates after 1 and 2 years of conventionally and early loaded pairs of unsplinted ITI implants supporting mandibular overdentures in edentulous patients. Twenty-four participants (age range 55-80 years) were randomly allocated with maximum concealment to two treatment groups. In the first group, the implants were allowed to heal for 12 weeks before being functionally loaded (control) and the second group had 6 weeks of healing with identical loading. All participants had new conventional complete maxillary and mandibular dentures prior to the study. Two sandblasted large-grit acid-etched (SLA) surface ITI implants were placed in the mandibular interforaminal area, following a standardized nonsubmerged surgical protocol. After 6 or 12 weeks of healing, matrices were processed into the fitting surface of the pre-existing mandibular dentures and the implants loaded. Implant success was determined using mobility tests and radiographs taken at baseline and 52 and 104 weeks after surgery. Clinical peri-implant parameters were also documented. Results showed all implants successfully osseointegrated, according to accepted criteria, after 2 years. Mean loss of crestal bone height after 1 year was 0.35 +/- 0.22 mm (control) vs. 0.27 +/- 0.18 mm (test). After 2 years this reduced to 0.09 +/- 0.06 mm (control) vs. 0.12 +/- 0.17 mm (test). The mean Periotest value after 1 year was -4.9 (control) vs.-3.78 (test). After 2 years, the mean resonance frequency value for the control implants was 6797 Hz [mean implant stability quotient (ISQ) = 64.77] and for the test implants 6670 Hz (mean ISQ = 62.0). Shortened loading periods for these ITI implants did not cause any statistically significant differences in osseointegration or peri-implant parameters. We conclude that pairs of unsplinted SLA-surface ITI implants can be successfully loaded with mandibular overdentures 6 weeks after surgery.     

Ninety percent success in palatal implants loaded 1 week after placement: a clinical evaluation by resonance frequency analysis

To investigate the behaviour of early loaded palatal implants when observed with resonance frequency analysis (RFA). Twenty patients (seven males and 13 females, mean age 26.4 years) received one palatal implant each (length: 4 mm, diameter: 3.3 mm; Orthosystem) for maximum orthodontic anchorage. The implants' stability was observed by RFA. Measurements were carried out at the time of surgery, after first orthodontic loading and subsequently once a week over a period of 12 weeks. Two palatal implants were lost. The other 18 remained stable. The average period from insertion to first loading was 6.7+/-0.8 days. The mean orthodontic force applied was 272.2+/-73.2 cN. The implant stability quotient (ISQ) value at the time of surgery averaged 69.4+/-3.9. The mean ISQ value 6.7 days after insertion was 69.8+/-3.6. Twelve weeks post-surgery the mean ISQ value was 69.8+/-3.5. A statistically significant decrease in stability was observed after 2 and 3 weeks post-surgery (P=0.005 and 0.04). The behaviour of early loaded palatal implants showed an initial decrease of the ISQ values. From 6 weeks post-surgery onward the ISQ values increased. Within the limitations of this study, the results suggest that the healing time of palatal implants reported in the literature (12 weeks) should be discussed. An orthodontic loading of palatal implants 6 weeks post-surgery with a force up to 400 cN seems to be justified. Yet further investigations are necessary to evaluate the behaviour of early loaded palatal implants considering observation periods of over 12 weeks.     

Resonance frequency analysis measurements of implants at placement surgery

PURPOSE: The knowledge of what levels of primary stability can be obtained in different jawbone regions and of what factors influence primary stability is limited. The objective of this study was to evaluate primary stability by resonance frequency analysis (RFA) measurements of implants placed according to a surgical protocol that aimed for high primary stability. The aim was also to correlate RFA measurements with factors related to the surgical technique, the patient, and implant design. MATERIALS AND METHODS: A total of 905 Br?nemark dental implants used in 267 consecutive patients were measured with RFA at the time of placement surgery. RESULTS: A mean ISQ value of 67.4 (SD 8.6) was obtained for all implants. Univariate analyses with the implant or patient as unit showed higher ISQ values in men compared with women, in mandibles compared with maxillae, in posterior compared with anterior sites, and for wide-platform implants in comparison with regular/narrow-platform implants. There was a correlation between bone quality and primary stability, with lower ISQ values obtained for implants placed in softer bone. A lower stability was seen with increased implant length. A stepwise multiple regression analysis using the patient as unit showed that jaw type and gender had independent effects on primary stability. CONCLUSION: The results suggest that factors related to bone density and implant diameter/length may affect the level of primary implant stability. Furthermore, greater stability was observed in male than in female patients. High primary implant stability was achieved in all jaw regions, although the use of thinner drills and/or tapered implants cannot fully compensate for the effect of soft bone. The research design does not permit conclusions regarding long-term treatment outcome with implants.     

亲水性大颗粒喷砂酸蚀表面种植体骨愈合期的共振频率分析及早期负荷临床探讨

目的:应用共振频率分析仪检测Straumann亲水性大颗粒喷砂酸蚀表面(SLActive)种植体骨愈合期内稳定性变化及种植体早期负荷临床探讨。方法:49例患者共计植入68颗Straumann SLActive种植体,分别在植入即刻、术后1、3、6、10、12周测量种植体稳定性,种植体稳定商值(ISQ)>65的种植体于术后6周早期负荷。结果:术后1周ISQ呈小幅增长,术后3周下降至最低,之后逐渐上升。经方差分析在术后12周时ISQ的增长具有显著性差异,其余时点无显著性差异。放射片显示种植体周围边缘骨吸收小于1 mm,术后12周时种植体留存率达100%。种植体颌位对ISQ有显著影响(P<0.05),种植体直径、长度对ISQ无显著影响。结论:Straumann SLAc-tive种植体早期负荷具有较高的临床可预期性,临床中可以显著缩短治疗周期,共振频率分析是监测种植体稳定性变化的有效手段。     

Implant stability measurement of delayed and immediately loaded implants during healing

The purpose of the present study was (1) to measure the primary stability of ITI implants placed in both jaws and determine the factors that affect the implant stability quotient (ISQ) determined by the resonance frequency method and (2) to monitor implant stability during the first 3 months of healing and evaluate any difference between immediately loaded (IL) implants and standard delayed loaded (DL) implants. The IL and DL groups consisted of 18 patients/63 implants and 18 patients/43 implants. IL implants were loaded after 2 days; DL implants were left to heal according to the one-stage procedure. The ISQ was recorded with an Osstell apparatus (Integration Diagnostics AB, Gothenburg, Sweden) at implant placement, after 1, 2, 4, 6, 8, 10 and 12 weeks. Primary stability was affected by the jaw and the bone type. The ISQ was higher in the mandible (59.8+/-6.7) than the maxilla (55.0+/-6.8). The ISQ was significantly higher in type I bone (62.8+/-7.2) than in type III bone (56.0+/-7.8). The implant position, implant length, implant diameter and implant deepening (esthetic plus implants) did not affect primary stability. After 3 months, the gain in stability was higher in the mandible than in the maxilla. The influence of bone type was leveled off and bone quality did not affect implant stability. The resonance-frequency analysis method did not reveal any difference in implant stability between the IL and DL implants over the healing period. Implant stability remained constant or increased slightly during the first 4-6 weeks and then increased more markedly. One DL and IL implant failed; both were 8 mm long placed in type III bone. At the 1-year control, the survival rate of the IL and the DL implants was 98.4% and 97.7%, respectively. This study showed no difference in implant stability between the IL and DL procedures over the first 3 months. IL short-span bridges placed in the posterior region and full arch rehabilitation of the maxilla with ITI sandblasted-and-etched implants were highly predictable.     

Stability measurements of osseointegrated implants using Osstell in partially edentulous jaws after 1 year of loading: a pilot study

Background: The introduction of resonance frequency analysis (RFA) as a commercially available technique has made it possible to measure implant stability in implant stability quotient (ISQ) units at any time during the course of implant treatment and loading. However, no information on normal ISQ levels can be found in the literature. Purpose: The aim of this pilot study was to measure the stability of clinically successful implants in partially edentulous patients after 1 year of loading and to study the influence of jaw, anterior/posterior position, implant length, and marginal bone level on implant stability. Materials and Methods: Fourteen partially edentulous patients previously treated with 45 implants were subjected to clinical and radiographie evaluations and RFA measurements using Osstell (Integration Diagnostics, Sävedalen, Sweden) after 1 year of loading. Results: All 45 implants were stable, and implant stability levels were in the range of 57 to 82 ISQ units with a mean of 69 ± 6.5 ISQ after 1 year of loading. Mandibular implants were more stable than were maxillary ones. There were no differences between anterior and posterior implants. No correlation could be found between implant length and stability. Only minor marginal bone resorption was observed. Conclusions: The results from this limited material showed that successfully integrated implants have ISQ levels from 57 to 82 ISQ with a mean of 69 ISQ after 1 year of loading. Mandibular implants are more stable than are maxillary ones. High implant stability can be achieved with short implants and placement in posterior regions.     

Early loading of ITI implants supporting maxillary fixed full-arch prostheses

Objective: To evaluate the predictability of the early‐loaded sand‐blasted, large‐grit and acid‐etched (SLA) implants supporting maxillary‐fixed full‐arch prostheses. Material and methods: Ninety‐one ITI SLA implants were placed in 12 edentulous maxillae. The impressions were taken at 4 weeks post‐surgery. The abutments were tightened and the final fixed prostheses were cemented at 6 weeks after implant placement. Resonance frequency analysis (RFA) was conducted on the day of the surgery, at 4 and 6 weeks post‐surgery. Panoramic radiographs were taken immediately after surgery, at 4 weeks post‐surgery, immediately after prostheses attachment (baseline) and at the yearly follow‐ups. Results: The survival rate of implants was 98.90%. The success rate of prostheses was 100% during the follow‐ups. The radiographic result showed no radiolucency around the implants and the marginal bone level revealed no significant resorption compared with the baseline. The marginal bone level remained coronally beyond the first thread. The RFA results revealed Implant Stability Quotient (ISQ) values of 63.44±4.32, 57.14±4.25 and 66.43±3.78 for the three time points. Conclusions: The findings of this study indicated that early loading of ITI implants supporting maxillary fixed full‐arch prostheses should be predictable.     

A 1‐Year Controlled Clinical Trial of Immediate Implants Placed in Fresh Extraction Sockets: Stability Measurements and Crestal Bone Level Changes

Purpose: The aim of this study was to measure stability and crestal bone level changes of implants placed in fresh extraction sockets in elderly patients. Methods: Thirty‐five patients who were in need of tooth extractions were recruited for this study. They received a total of 65 implants in both jaws to support fixed or removable prostheses. The teeth were carefully extracted, the implants set directly in the root socket, and resonance frequency analysis (RFA) measurements were simultaneously performed (Time 1 = T1). After a healing time of 6 to 10 weeks the measurements were repeated (Time 2 = T2). Orthograd periapical radiographs were taken when the new prostheses were fabricated and after 1 year of loaded period. The distance between the first visible bone implant contact (BIC) and the implant‐shoulder was measured and crestal bone loss was calculated (ΔBIC). Mean RFA and BIC were compared for various subgroups (p < .05). By means of a fixed effects model, the impact of the parameters gender, jaw, and prosthetic indication on RFA measurements was analyzed (p < .016). Results: The mean implant stability quotient (ISQ) values were 64.4 ± 6.7 at T1 and 64.0 ± at 8.6 T2, with a trend to higher values for male patients. The mixed model showed that only the jaw had a statistically significant impact on ISQ values, with higher values for the mandible. Mean crestal bone loss was small with 0.49 ± 0.81 mm, ranging form 0.1 to 2.4 mm. Twenty percent of the implant sites lost more than 1‐mm crestal bone. No differences were found in subgroups. Conclusions: Good primary and secondary stability of the implants was reached in both jaws. Crestal bone loss was small but may not be fully predictable for a single site. This treatment modality can be applied successfully in elderly patients and can be suggested for various prosthetic indications in both jaws.     

Predicting osseointegration by means of implant primary stability

The purpose of the present clinical study was (1) to evaluate the Osstell as a diagnostic tool capable of differentiating between stable and mobile ITI implants, (2) to evaluate a cut-off threshold implant stability quotient (ISQ) value obtained at implant placement (ISQitv) that might be predictive of osseointegration, (3) to compare the predictive ISQitv of immediately loaded (IL) implants and implants loaded after 3 months (DL). Two patient groups were enrolled, 18 patients received 63 IL implants and 18 patients were treated with 43 DL implants. The ISQ was recorded at implant placement, after 1, 2, 4, 6, 8, 10 and 12 weeks. All implants passed the 1-year loading control. Two implants failed, one DL implant with ISQ at placement (ISQi) of 48 and one IL implant with ISQi of 53. The resonance-frequency analysis (RFA) method was not a reliable diagnostic tool to identify mobile implants. However, implant stability could be reliably determined for implants displaying an ISQ> or =47. After 1 year of loading, all DL implants with an ISQi> or =49 and all IL implants with an ISQi> or =54 achieved and maintained osseointegration. By the end of 3 months, implants with ISQi<60 had an increase of stability. Implants with ISQi 60-69 had their stability decrease during 8 weeks before returning to their initial values. Implants with ISQ>69 had their stability decrease during the first 4 weeks before remaining stable. Although preliminary, these data might orient the practitioner to choose among various loading protocols and to selectively monitor implants during the healing phase.     

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.     

Report of a case receiving full-arch rehabilitation in both jaws using immediate implant loading protocols: a 1-year resonance frequency analysis follow-up

Background: Immediate occlusal implant loading has been documented as a viable treatment option for various indications. However, documentations related to full‐arch rehabilitation are usually limited to treatment of one jaw at a time, thereby leaving the opposing dentition unchanged. Furthermore, clinical documentation using traditional, well‐accepted measuring techniques may not be adequate when it comes to short‐term evaluation of the success or failure of implants subjected to immediate occlusal loading. Purpose: The purpose of this case report is to (1) present an implant stability follow‐up of a patient receiving an immediate, implant‐supported full‐arch rehabilitation in both jaws and (2) evaluate the patient's acceptance of this rehabilitation. Materials and Methods: A 68‐year‐old patient scheduled for implant treatment was selected for an immediate implant loading protocol in both jaws. During two surgical events 3 weeks apart, eight maxillary and four mandibular Brånemark System® Mk IV TiUnite^TM fixtures (Nobel Biocare AB, Göteborg, Sweden) were inserted and subsequently used to immediately support a cross‐arch fixed prosthesis in the maxilla and a bar‐retained overdenture in the mandible. Implant stability was recorded from the day of surgery periodically during a 1‐year follow‐up using resonance frequency analysis (RFA). Results: At the 1‐year follow‐up, based on clinical, RFA, and radiographic evaluations, all implants and the reconstructions were classified as successful. All maxillary implants showed a decrease in the implant stability quotient (ISQ) value from the measurement at the time of surgery to the first follow‐up, whereas two of four mandibular implants revealed an initial drop in stability. Irrespective of a specific ISQ level measured at implant surgery (ISQ range 53–74) and despite an initial decrease in stability, measurements recorded at the 12‐month follow‐up indicated similar stability levels for all maxillary implants (ISQ range 64–68) or the group of mandibular implants (ISQ range 72–75) but with a higher ISQ level for mandibular implants. Furthermore, the patient's acceptance of the immediate full‐arch rehabilitation in both jaws was high. Conclusions: The present case report demonstrates that a slightly staged approach for full‐arch rehabilitation in both jaws using immediate implant loading protocols is a realistic treatment option. Furthermore, RFA follow‐up indicates that immediately occlusally loaded implants placed in reduced bone quality and quantity are more prone to loose stability in the early healing period compared with implants placed in dense bone quality.     

Human ex vivo bone tissue strains around immediately loaded implants supporting maxillary overdentures

PURPOSE: To evaluate ex vivo bone tissue strains around maxillary implants supporting immediately loaded bar-retained overdentures. MATERIAL AND METHODS: Ninety degree two-element rosette strain gauges were bonded on the labial bone of four ITI dental implants placed in the maxillary anterior region of four completely edentulous maxilla of fresh human cadavers. The installation torque value (ITV) of each implant was measured by a custom-made torque wrench and resonance frequency analyses (RFAs) were undertaken. A bar-retained overdenture was fabricated for each cadaver, and two miniature load cells were integrated in the first molar region of the overdentures for controlled loading experiments. Strain measurements were performed at a sample rate of 10 kHz and under a maximum load of 100 N, simultaneously monitored from a computer connected to a data acquisition system. Finally, removal torque values (RTVs) of the implants were measured. RESULTS: RFA values did not mirror ITVs, while RTVs of implants were slightly lower than the ITVs. Any correlation could not be obtained between RFA values and ITVs or RTVs. Maximum strains around loaded implants ranged between -100 and -550 microepsilon under 25-100 N. The axial and lateral strain values of posterior implants of both sides were higher than those of anterior implants under all loads (P<0.05). CONCLUSION: Because occlusal forces in humans tend to decrease because of age-related factors, maximum strains around immediately loaded implants supporting maxillary overdentures fall within physiologic levels.     

Reliability and validity of the instrumental assessment of implant stability in dry human mandibles

Summary  The aim of this study was to determine the intra- and interobserver reliability and validity of the instrumental assessment of primary dental implant stability, using resonance frequency analysis (RFA). Sixteen tapered implants and 16 cylindrical implants were installed in eight unfixed dry human mandibles (Cawood classification IV/V). Implant stability quotients (ISQ; the outcome variable of RFA) and peak removal torque were determined. Both the intra-observer reliability and the interobserver reliability of the RFA measurements were fair-to-good, while no significant correlations between the ISQ values and removal torque were found. The removal torque of the cylindrical implants was higher than that of the tapered implants. The smallest detectable difference was almost nine ISQ units. Within the limitations of the present dry cadaver study, it was concluded that (i) primary dental implant stability can be assessed reliably with RFA measurements, (ii) the concurrent validity between RFA measurements and removal torque is poor, (iii) cylindrical implants may be more stable than tapered ones and (iv) two subsequent readings of RFA measurements need to differ at least nine ISQ units before the difference between the two measurements can be considered statistically significant. More research is needed to see whether these conclusions can be extrapolated to the clinical situation, including the assessment of implants during function (secondary stability).     

Resonance frequency analysis assessment of implant stability in labial onlay grafted posterior mandibles: a pilot clinical study

PURPOSE: The objectives of this study were (1) to compare the stability, evaluated by means of resonance frequency analysis (RFA), of implants placed posterior mandibles augmented with autogenous bone harvested from the mandibular symphysis with that of implants placed in nongrafted edentulous posterior mandibles and (2) to compare peri-implant marginal bone height changes and implant failure for the 2 groups. MATERIALS AND METHODS: Eight patients with thin posterior mandibular ridges (buccolingual crestal width less than 4 mm) underwent labial onlay alveolar grafting with symphyseal bone blocks 4 months prior to placement of 17 implants. Seven nongrafted patients received 18 implants in the edentulous posterior mandible; these patients served as a control group. RFA was performed the day of implant placement (baseline), 1 month postplacement, 4 months postplacement (after prosthesis delivery), and 12 months postloading. Peri-implant bone height changes at a level of 0.01 mm were assessed using periapical radiographs at baseline, the 1-month follow-up, and the 4-month follow-up. Analysis of variance was used to evaluate statistical differences within the groups, and t test was used to make comparisons between groups. RESULTS: None of the patients presented postoperative complications or implant failure. Mean implant stability quotient (ISQ) was 63.0+/-6.0 to 70.2 +/-3.5 for the grafted group and 64.1+/-4.1 ISQ to 70.1+/-3.9 for the nongrafted group. No significant difference was found in mean ISQ between the grafted and nongrafted groups at baseline, the 1-month follow-up, 4 months postplacement, or 12 months postloading (P = .211, P = .873, P = .925, P = .735, respectively). Mean peri-implant bone loss was 0.16 +/- 0.04 mm mesially and 0.16 +/- 0.05 mm distally. CONCLUSION: RFA revealed no difference in implant stability between mandibular ridges augmented with autologous bone grafts at baseline or after loading.     

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.     

Parameters of resonance frequency measurement values: a retrospective study of 385 ITI dental implants

OBJECTIVES: There is no proven clinical tool to evaluate the amount of osseointegration and stability around dental implants. Therefore, the aim of this retrospective clinical study was to evaluate resonance frequency analysis values of 385 ITI solid screw implants. MATERIAL AND METHODS: Both at implant placement and after healing, implant stability quotients (ISQs) were determined. For statistical analysis, Pearson's correlation coefficients, Welch's two-sample t-tests and paired samples t-tests were computed at a level of significance of alpha=0.05. RESULTS: ISQ values ranged from 39 to 86 at implant placement and from 35 to 89 after healing, showing a significant increase. The highest ISQ values at both stages were obtained in the posterior mandible (P < or = 0.002). After healing, ISQ values in the anterior mandible were significantly higher than in the anterior maxilla (P=0.005). Implant length had a significant influence on ISQ in the anterior mandible (P=0) at insertion and in the anterior (P=0.005) and posterior mandible (P=0.036) after healing. Implant diameter and ISQ at insertion correlated in the anterior mandible (P=0.037). After healing, a significant influence was found for all regions, except the posterior maxilla (P=0.795). With the exception of the anterior maxilla (P=0.542), ISQ at placement had a significant influence on ISQ after healing. In the anterior maxilla (P=0.002) and in the posterior mandible (P=0.007), healing time significantly influenced ISQ after healing. CONCLUSIONS: It appears that only repeated ISQ measurements of a specific implant have some diagnostic benefit, although the parameters influencing the absolute values still remain unclear.