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Concept: Implant stability quotient


Background: There are a few prospective studies reporting on new implant systems. When a new implant is brought to market, prospective trials should be carried out to determine the predictability of that system. Purpose: This prospective study evaluates implant survival, Resonance Frequency Analysis (RFA), and crestal bone level changes for a new implant system (Neoss System, Bimodal surface, Neoss Ltd, Harrogate, UK). Materials and Methods: Seventy-six patients, 38 females (age ranging from 23 to 57 years) and 38 males (ranging in age from 17 to 85 years) received 100 Neoss implants. Patients were consecutively enrolled in the study if they were missing one or more teeth in either arch, or a single tooth was scheduled for removal and immediate implant replacement. Evaluated implants were 4, 4.5, or 5 mm wide and were 7, 9, 11, 13, or 15 mm long. A one-stage approach was followed. At first stage and prior to healing abutment placement RFA measurements were taken. Measurements were retaken at second stage. Fifty-one implants were placed for restoration of single missing teeth and 49 were for short span implant bridges. Results: The cumulative survival rate at 1- to 2-year interval was 93%. Average initial RFA measurement for all implants was 72.06, while the average final score was 72.58. These changes were not statistically significant. Changes in RFA scores for maxillary implants were insignificant. Forty-two paired mandibular RFA measurements were evaluated. Initial and final mean mandibular RAF measurements were 73.65 (SD 9.203) and 77.186 (SD 6.177), respectively. These changes were statistically significant (p = .02). Sixty-four paired radiographs were available for evaluation. Between examinations, there was an average -0.6 mm of bone loss, which was statistically significant (p = .03). On average, 4.0-mm-wide implants lost 0.1 mm of bone when compared with 5-mm-wide implants. These differences were insignificant (p = .86). Bone loss was adjusted for implant length, and tooth position and there were small, but clinically insignificant changes. Five-millimeter-wide implants lose 0.2 mm more than 4.0-mm-wide implants (p = .7). Maxillary incisors lose the least amount of bone 0.152 (p = .33). Conclusions: The implants tested in this study had initially high RAF readings, indicating good primary stability. RFA readings for implants placed in the mandible improved from baseline and the changes were statistically significant. Marginal bone levels revealed clinically insignificant bone loss from implant installation to second stage. Loss of seven implants with initially high RFA readings is surprising.

Concepts: Statistics, Teeth, Dental implant, Dentistry, Resonance, Resonance Frequency Analysis, Implant stability quotient, Electrical resonance


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.

Concepts: Male, Dental implant, Dentistry, Resonance, Resonance Frequency Analysis, Implant stability quotient


Many surgical procedures use metal implants in bone. The clinical results depend on the strength of the bone holding these implants. Our objective was to show that a drug released from the implant surface can improve parameters reflecting the quality or amount of this bone. Sixteen patients received paired dental titanium implants in the maxilla, in a randomized, double-blinded fashion. One implant in each pair was coated with a thin fibrinogen layer containing 2 bisphosphonates. The other implant was untreated. Fixation was evaluated by measurement of resonance frequency (implant stability quotient; ISQ) serving as a proxy for stiffness of the implant-bone construct. Increase in ISQ at 6months of follow-up was the primary variable. None of the patients had any complications. The resonance frequency increased 6.9 ISQ units more for the coated implants (p=0.0001; Cohen’s d=1.3). The average difference in increase in ISQ, and the effect size, suggested a clinically relevant improvement. X-ray showed less bone resorption at the margin of the implant both at 2months (p=0.012) and at 6months (p=0.012). In conclusion, a thin, bisphosphonate-eluting fibrinogen coating might improve the fixation of metal implants in human bone. This might lead to new possibilities for orthopedic surgery in osteoporotic bone and for dental implants.

Concepts: Osteoporosis, Improve, Surgery, Dental implant, Titanium, Dentistry, Resonance Frequency Analysis, Implant stability quotient


BACKGROUND: New implant designs are continuously introduced to the market. It is important to evaluate and report on their clinical performance when used in everyday practice. PURPOSE: The aim of the present study was to evaluate the clinical performance of a novel hydrophilic dental implant for 1 year. MATERIALS AND METHODS: A total of 49 patients previously treated with 102 hydrophilic dental implants (Neoss Proactive, Neoss Ltd, Harrogate, UK) were retrospectively evaluated with regard to survival rate and marginal bone loss. Fifty-four implants were installed in maxillae and 48 in mandibles to replace single teeth (n = 21), to support partial bridges (n = 26), total maxillary bridges (n = 2), or mandibular overdentures (n = 2). The majority of patients (n = 37) had implants placed in healed sites without any adjunctive procedures. In 12 patients, implants were immediately placed in extraction sockets or in conjunction with maxillary sinus floor augmentation. All implant sites had been classified according to the Lekholm and Zarb index. Baseline and 1-year intraoral radiographs were used to calculate marginal bone levels and bone loss. Implant stability quotient (ISQ) measurements had been taken at placement and after 3 to 4 months of healing RESULTS: The implants became rapidly covered with blood at the first contact. One implant was lost, giving a cumulative survival rate (CSR) of 99.0% after 1 year. The marginal bone loss amounted to 0.7 ± 0.6 mm with 3.5% of the implants showing more than 2 mm of bone loss and no implant more than 3 mm bone loss after 1 year. The primary stability was found to be 72.7 ± 7.5 ISQ, which slightly increased to 73.6 ± 7.2 ISQ (NS) after 3 to 4 months of healing. The stability was significantly higher in the mandible than in the maxilla at placement and after healing. CONCLUSION: In this limited clinical study, the use of a novel hydrophilic dental implant results in favorable short-term outcomes.

Concepts: Mandible, Implants, Dental implant, Titanium, Dentistry, Osseointegration, Implant stability quotient, Maxilla


This study aimed to compare the primary and secondary stability, measured by Resonance Frequency Analysis (RFA), in implants of different lengths installed in areas submitted to maxillary sinus lift. Correlation between RFA and implant insertion torque was also assessed. Twenty implants of 9 and 11 mm were inserted in areas submitted to maxillary sinus lift. The insertion torque was measured by the Bien Air® motor. Osstell®, through RFA, determined the ISQ (Implant Stability Quotient) at two times: the day of implant installation (T1) and 90 days after implant installation (T2). No differences were observed in the ISQ between T1 and T2 when the 20 implants were grouped, nor when the 9 mm implants were evaluated separately. In contrast, when the 11 mm values ​​were evaluated separately, the ISQ was significantly higher in T2 than in T1 (p <0.05). In T1, 9 mm implants had a higher ISQ than 11 mm ones (p <0.05), whereas in T2 the implants of 11 mm showed a higher ISQ than the 9 mm implants did (p <0.05). There was no difference in insertion torque between 9 and 11 mm implants (p> 0.05), nor was there a correlation between ISQ and insertion torque (p> 0.05). In conclusion, longer implants (11 mm) presented a significant increase in ISQ values ​​during the healing period when installed in areas previously submitted to maxillary sinus lift. This phenomenon was not observed for shorter implants (9 mm). Finally, no correlation was observed between ISQ and insertion torque.

Concepts: Resonator, Nuclear magnetic resonance, Dental implant, Maxillary sinus, Dentistry, Resonance, Resonance Frequency Analysis, Implant stability quotient


Histology is still regarded as the gold-standard to determine bone implant contact (BIC) as a parameter representing implant stability. As the further processing of cut slices for contact radiography (CR) to stained and polished histological sections is time consuming and error prone, our aim was to assess agreement between CR and Giemsa-eosin (GE) stained sections with regard to dental implants.

Concepts: Implants, Prosthetics, Anatomy, Dental implant, Dentistry, Osseointegration, Implant stability quotient, Per-Ingvar Brånemark


Resonance frequency analysis (RFA) is clinically used in dentistry to access the stiffness of dental implants in surrounding bone. However, the clear advantages and disadvantages of this method are still inconclusive. The aim of this study was to investigate and compare implant stability quotient (ISQ) values obtained from RFA with parameters obtained from a cone beam computed tomography (CBCT) scan of the same region.

Concepts: Wave, Dental implant, Sound, Dentistry, Resonance, Radio, Resonance Frequency Analysis, Implant stability quotient


The effect of platelet-rich fibrin (PRF) on bone healing around dental implants in areas of poor bone quality has not been studied. The aim of this study was to evaluate the stability of implants placed in the posterior maxilla, with or without the use of PRF, during the healing period. A split-mouth randomized clinical trial was performed. Twenty patients with missing teeth in the molar region of the maxilla, requiring bilateral implants, were included. PRF was used on one side (group 1); no PRF was used on the other (group 2). Implant stability was assessed by resonance frequency analysis (RFA) at 2, 4, and 6 weeks after placement. At 2 weeks, the mean ISQ was 60.60±3.42 in group 1 and 58.25±3.64 in group 2; at 4 weeks it was 70.30±3.36 in group 1 and 67.15±4.33 in group 2; at 6 weeks it was 78.45±3.36 in group 1 and 76.15±2.94 in group 2. Significant differences in RFA were found between the groups at 2 weeks (P=0.04), 4 weeks (P=0.014), and 6 weeks (P=0.027) after placement. The study results suggest that the use of PRF may enhance the post-insertion stability of dental implants placed in the posterior maxilla during the healing period.

Concepts: Clinical trial, Wave, Dental implant, Dentistry, Resonance, Radio, Resonance Frequency Analysis, Implant stability quotient



The influences of potential bone-to-implant contact (BIC) area (pBICA), BIC area (BICA), and three dimensional (3D) BIC percentage (3D BIC%; defined as BICA divided by pBICA) in relation to the implant length on initial implant stability were studied. Correlations between these parameters were also evaluated.

Concepts: Dental implant, C, Dentistry, Osseointegration, Implant stability quotient, Elementary arithmetic