Low Primary Stability Research Articles

Management of Advanced Peri-Implantitis by Guided Bone Regeneration in Combination with Trabecular Metal Fixtures, Two Months after Removal of the Failed Implants: Two-Year Results of a Single-Cohort Clinical Study

Background: Implant replacement is among the treatment options for severe peri-implantitis. The aim of this single-cohort study was to evaluate the feasibility of replacing compromised implants affected by advanced peri-implantitis with new implants with a porous trabecular metal (TM) structure. Materials and Methods: Patients with one or more implants in the posterior region showing a defect depth >50% of implant length, measured from the residual crest, were consecutively included. Two months after implant removal, patients received a TM implant combined with a xenograft and a resorbable membrane. The implant stability quotient (ISQ) was measured at placement and re-assessed five months later (at uncovering), then after 6, 12, and 24 months of function. Marginal bone loss was radiographically evaluated. Results: Twenty consecutive cases were included. One patient dropped out due to COVID-19 infection, and nineteen cases were evaluated up to 24 months. At placement, the mean ISQ was 53.08 ± 13.65 (standard deviation), which increased significantly to 69.74 ± 9.01 after five months of healing (p < 0.001) and to 78.00 ± 7.29 after six months of loading (p < 0.001). Thereafter, the ISQ remained stable for up to 24 months (80.55 ± 4.73). All implants successfully osseointegrated and were restored as planned. After two years, the average marginal bone level change was −0.41 ± 0.38 mm (95% confidence interval −0.60, −0.21), which was limited yet significantly different from the baseline (p < 0.05). Conclusions: The treatment of advanced peri-implant defects using TM implants inserted two months after explantation in combination with guided bone regeneration may achieve successful outcomes up to two years follow-up, even in the presence of low primary stability.

Tissue-engineered bone construct promotes early osseointegration of implants with low primary stability in oversized osteotomy

ObjectivesTo evaluate the histological parameters and bone mechanical properties around implants with low primary stability (PS) in grafted bone substitutes within an oversized osteotomy.Materials and methodsAn oversized osteotomy penetrating the double cortical bone layers was made on both femora of 24 New Zealand white rabbits. Bilaterally in the femur of all animals, 48 implants were installed, subdivided into four groups, corresponding to four prepared tissue-engineering bone complexes (TEBCs), which were placed between the implant surface and native bone wall: A: tricalcium phosphate β (TCP-β); B: autologous adipose derived-stem cells with TCP-β (ASCs/TCP-β); C: ASCs transfected with the enhanced-GFP gene with TCP-β (EGFP-ASCs/TCP-β); D: ASCs transfected with the BMP-2 gene with TCP-β (BMP2-ASCs/TCP-β). Trichrome fluorescent labeling was conducted. Animals were sacrificed after eight weeks. The trichromatic fluorescent labeling (%TFL), area of new bone (%NB), residual material (%RM), bone-implant contact (%BIC), and the removal torque force (RTF, N/cm) were assessed.ResultsASCs were successfully isolated from adipose tissue, and the primary ASCs were induced into osteogenic, chondrogenic, and adipogenic differentiation. The BMP-2 overexpression of ASCs sustained for ten days and greatly enhanced the expression of osteopontin (OPN). At eight weeks post-implantation, increased %NB and RTF were found in all groups. The most significant value of %TFL, %BIC and lowest %RM was detected in group D.ConclusionThe low PS implants osseointegrate with considerable new bone in grafted TEBCs within an oversized osteotomy. Applying BMP-2 overexpressing ASCs-based TEBC promoted earlier osseointegration and more solid bone mechanical properties on low PS implants. Bone graft offers a wedging effect for the implant with low PS at placement and promotes osteogenesis on their surface in the healing period.

Cortical bone microdamage affects primary stability of orthodontic miniscrew.

The aim of this study was to investigate the effects of orthodontic miniscrew pitch and thread shape on microdamage in cortical bone. The relationship between the microdamage and primary stability was also examined. Ti6Al4V orthodontic miniscrews and 1.0-mm-thick cortical bone pieces from fresh porcine tibia were prepared. The orthodontic miniscrews had custom-made thread height (H) and pitch (P) size geometries, and were classified into three groups: control geometry; HCPC (HC; thread height=0.12 mm, PC; pitch size=0.60 mm), geometry with a narrower pitch; HCPN (HC; thread height=0.12 mm, PN; pitch size=0.30 mm), and geometry with a taller thread height; HTPC (HT; thread height=0.36 mm, PC; pitch size=0.60 mm). The orthodontic miniscrews were inserted into a pilot hole in the cortical bone, and maximum insertion torque and Periotest value were measured. After insertion, the samples were stained with basic fuchsin. Histological thin sections were obtained and the bone microdamage parameters, i.e., total crack length and total damage area, and insertion state parameters, i.e., orthodontic miniscrew surface length and bone compression area were calculated. The orthodontic miniscrews with the taller thread height resulted in lower primary stability with minimal bone compression and microdamage; however, the narrower thread pitch led to maximum bone compression and extensive bone microdamage. A wider thread pitch reduced microdamage, and decreased thread height resulted in increased bone compression, ultimately resulting in increased primary stability.

Effect of Implant Length and Insertion Depth on Primary Stability of Short Dental Implant

Purpose: To evaluate the effect of insertion depth, bone type, and implant diameter on the primary stability of short implants. Materials and Methods: Commercial dental implants with different lengths (6 and 8 mm; BLX, Straumann) were inserted into artificial bone specimens of good and poor quality at three different depth positions: equicrestal, 1-mm subcrestal, and 2-mm subcrestal. Insertion torque values were recorded spontaneously during the implant procedure. Both maximum insertion torque values (MITVs) and final insertion torque values (FITVs) were recorded. Subsequently, Periotest values (PTVs) and implant stability quotients (ISQs) were measured for all specimens. Results: The mean MITVs of all groups ranged from 31.8 to 46.2 Ncm. However, the mean FITVs of all groups ranged from 8.8 to 29 Ncm. Torque values decreased significantly when the implants were inserted into their final positions. When insertion depth was increased, the PTV and ISQ decreased. Long implants and implants inserted into good-quality bone yielded greater primary stability, and bone quality appeared to have a greater effect on primary stability. Conclusion: When 6-mm short implants are inserted in a subcrestal position, low primary stability may be yielded, particularly in poor-quality bone.

Patient factors related to early implant failures in the edentulous jaw: A large retrospective case-control study.

Dental implants provide anchorage for dental prostheses to restore functions for individuals with edentulous jaws. During the healing phase, proper osseointegration is required to prevent early implant failure. More knowledge is needed regarding factors related to early failure of dental implants. The aim of the present study was to identify possible risk factors for early implant failure, with respect to anamnestic and clinical parameters. All patients with edentulous jaws with early implant failure (n=408) from one referral clinic were compared with a matched control group (n=408) with no implant failure. Early implant failure was identified during the first year of prosthetic function. Matching was performed on age, gender, year of surgery, type of jaw, and type of implant surface. In addition, data on anamnestic and clinical parameters were collected. The data were analyzed with a multivariable logistic regression model using early implant failure as the binary outcome. Five anamnestic factors were statistically significant with respect to higher probability for early implant failure: systemic disease, allergies in general, food allergies, smoking, and intake of analgesic medication. Four clinical conditions (i.e., implants in the opposing jaw, low primary stability, reduced bone volume, and healing complications) were also related to higher probability for early implant failure. This study identified nine factors associated with early implant failure, several related to patient's general health. Further investigations are needed to fully understand the causality between the obtained variables and early implant failure.

Clinical osseointegration of bone level implants with conical shape and textured surface with low primary stability

Evidence shows lower chance for osseointegration of implants without sufficient primary stability. The present retrospective study observed bone level conical screw implants with textured surface without primary stability. Twenty-six Stark conical screw implants, with V-Blast (Vanish Blast) surface treatment were placed with low primary stability, (insertion torque lower than 10 N/cm and visible mobility at lateral load of 250 g). A soft diet was prescribed. osseointegration was assessed applying 30 Ncm of reverse torque 6 months after placement. The 26 implants that did not achieve primary stability still had a survival rate of 96% after the observation period and were classified as successful according with ICOI Pisa consensus conference success, survival, failure classification .96% of the implants showed clinical osteointegration and were successfully restored. After 12 months, all implants remained functional. It can be concluded that bone-level implants with V-Blast surface in absence of functional loading are able to achieve osteointegration, even with low primary stability.

A retrospective study evaluating the survival and radiographic outcome of implants with low primary stability

A retrospective study evaluating the survival and radiographic outcome of implants with low primary stability

Mathematical equations for dental implant stability patterns during the osseointegration period, based on previous resonance frequency analysis studies.

Total stability of dental implant can be obtained from resonance frequency analysis (RFA) device, but without primary and secondary stability values. To formulate mathematical equations for dental implant stability patterns during the osseointegration period. An online systematically search of the literature between January 1996 and December 2017 was performed for all prospective clinical trials that measured implant stability using RFA device during the osseointegration period. Initial mathematical function with adjustable parameters were created. Then curve-fitting was performed using a computerized program to formulate mathematical equations stability patterns. Nine publications (24 study groups) were included in the mathematical analysis. Curve fitting with low sum of squared errors could be applied in all studies, except one. The stability has been divided into high, medium, and low stability. The curve fitting showed stability dip areas and intersection point which predict the returning of the stability to reach the primary stability. The study groups with low primary stability showed the poorest results, the high and medium stability group showed the stability pattern following the assumed primary stability pattern according to the mathematic equations. The model of primary and secondary stability could be predicted from the proposed equations.

A retrospective case series evaluating the outcome of implants with low primary stability.

There is a need of more studies on whether low primary implant stability would negatively influence the success of implant therapy. Therefore, this retrospective study analyses outcomes of implants placed with low primary stability and factors that may be related to implant failures. This retrospective study included 156 patients, restored with 169 implants that presented manual rotation within an observed follow-up time of a minimum of 34days and a maximum of 9.28years. Descriptive statistics, survival analyses (life tables and Kaplan-Meier estimates) and radiographic assessment based on marginal bone level measurements were performed. This original study was adherent to STROBE guidelines. Seven implants failed in seven patients, rendering cumulative survival rates of 94.74% (95% CI: 89.11-97.50) and 94.33% (95% CI: 88.30-97.30) at implant and patient levels, respectively. Kaplan-Meier estimates showed implant loss was found only in advanced surgery group (7 implant loss in 82 implants) when compared with simple surgery group (no implant loss in 87 implants; p=0.005). Within the limitations of this retrospective study, implant placement with low primary stability might not negatively affect either the survival rates or marginal bone level changes of implants provided that a protected and unloaded healing is guaranteed.

The influence of bone graft procedures on primary stability and bone change of implants placed in fresh extraction sockets

BackgroundThis study was to evaluate the effect of bone graft procedure on the primary stability of implants installed in fresh sockets and assess the vertical alteration of peri-implant bone radiographically.MethodsTwenty-three implants were inserted in 18 patients immediately after tooth extraction. The horizontal gap between the implant and bony walls of the extraction socket was grafted with xenografts. The implant stability before and after graft procedure was measured by Osstell Mentor as implant stability quotient before bone graft (ISQ bbg) and implant stability quotient after bone graft (ISQ abg). Peri-apical radiographs were taken to measure peri-implant bone change immediately after implant surgery and 12 months after implant placement. Data were analyzed by independent t test; the relationships between stability parameters (insertion torque value (ITV), ISQ abg, and ISQ bbg) and peri-implant bone changes were analyzed according to Pearson correlation coefficients.ResultsThe increase of ISQ in low primary stability group (LPSG) was 6.87 ± 3.62, which was significantly higher than the increase in high primary stability group (HPSG). A significant correlation between ITV and ISQ bbg (R = 0.606, P = 0.002) was found; however, age and peri-implant bone change were not found significantly related to implant stability parameters. It was presented that there were no significant peri-implant bone changes at 1 year after bone graft surgery.ConclusionsBone graft procedure is beneficial for increasing the primary stability of immediately placed implants, especially when the ISQ of implants is below 65 and that bone grafts have some effects on peri-implant bone maintenance.

The Use of Photofunctionalized Implants for Low or Extremely Low Primary Stability Cases.

The objective of this study was to examine the success rate and development of implant stability of photofunctionalized implants with low and extremely low primary stability. Primary implant stability was evaluated by measuring implant stability quotients (ISQs) at placement (initial ISQ). Of 301 consecutive implants placed over 2 years, 55 implants (in 38 patients) with initial ISQs less than 60 were included. All implants were photofunctionalized by chairside treatment with ultraviolet light for 15 minutes using a photo device immediately prior to placement, and the generation of superhydrophilicity and hemophilicity was confirmed. The rate of implant stability development was evaluated by calculating the osseointegration speed index (OSI), defined as the ISQ increase per month. Most of the 55 implants (90.9%) were in complex cases and placed in site-developmental sites with simultaneous or staged guided bone regeneration and/or sinus elevation or fresh extraction sites. The success rate was 98.2% after 2 to 3 years of follow-up. The ISQ for all implants was 50.4 ± 7.7 at placement and 74.3 ± 5.7 at stage-two surgery (P < .001) after an average of 7.1 months of healing. All ISQ values were greater than 60 at the stage-two surgery. ISQ increases were inversely correlated with initial ISQ (R = 0.789) and resulted in consistently high ISQs at the stage-two surgery regardless of the degree of the initial ISQ. Implants with absent primary stability for which ISQ measurement was not possible at placement also attained ISQs of 75 or greater at the stage-two surgery. The OSIs of low initial stability (55 or lower) implants ranged from 3.9 to 4.7, which was considerably higher than the OSIs of as-received implants reported in the literature (0.36 to 2.8). Photofunctionalized implants placed with low, extremely low, or absent primary stability showed a high success rate, which was corroborated with a rapid increase in implant stability during the healing. Photofunctionalization was more effective for implants with lower primary stability, indicating that the technology was particularly effective in mitigating the challenging conditions.

FGF-2 promotes initial osseointegration and enhances stability of implants with low primary stability.

ObjectivesThe aim of this study was to examine the effect of basic fibroblast growth factor (FGF‐2) on osseointegration of dental implants with low primary stability in a beagle dog model.Materials and methodsCustomized titanium implants that were designed to have low contact with the existing bone were installed into the edentulous mandible of beagle dogs. To degrade the primary stability of the implants, the diameters of the bone sockets exceeded the implant diameters. FGF‐2 (0.3%) plus vehicle (hydroxypropyl cellulose) or vehicle alone was topically applied to the sockets in the FGF‐2 and control groups, respectively. In Study 1, the new bone area and length of new bone‐to‐implant contact (BIC) were evaluated at 4, 8, and 12 weeks after installation using histomorphometry and scanning electron microscopy. In Study 2, the implant stability quotient (ISQ) values were sequentially measured for 16 weeks using an Osstell system.ResultsThe histomorphometric analysis revealed that the new bone area and length of BIC in the FGF‐2 group were significantly larger than those in the control group at 4 weeks. Electron microscopic observation showed intimate contact between the mature lamellar bone and the implant surfaces, osseointegration, in both groups. The ISQ values in the FGF‐2 group were significantly increased from 6 to 16 weeks compared with those in the control group.ConclusionsTaken together, our study demonstrates that FGF‐2 promoted new bone formation around the dental implants and subsequent osseointegration, resulting in promotion of stability of implants with low primary stability.

Mechanical Quantification of Local Bone Quality in the Humeral Head: A Feasibility Study

Objectives:Surgical treatment of proximal humerus fractures can be challenging due to osteoporosis. The weak bone stock makes stable implant anchorage difficult, which can result in low primary stability. Accordingly, significant failure rates, even with modern locking plates, are reported in the literature. Intraoperative knowledge of local bone quality could be helpful in improving results. This study evaluates the feasibility of local bone quality quantification using breakaway torque measurements.Materials and Methods:A torque measurement tool (DensiProbe™) was developed to determine local resistance to breakaway offered by the cancellous bone in the humeral head to quantify local bone quality. The tool was adapted to a standard locking plate (PHILOS, Synthes), allowing measurement in the positions of the six humeral head screws, as provided by the aiming device of the plate. Two hundred and seventy measurements were performed in 44 fresh cadaveric human humeri.Results:Handling of the tool was straight forward and provided reproducible results for the six different positions. The method allows discrimination between the respective positions with statistical significance, and thus provides reliable information on the local distribution of bone quality within the humeral head.Discussion:This study introduces a new method using breakaway torque to determine local bone quality within the humeral head in real time. Because DensiProbe is adapted to a standard locking plate, there is the potential for intraoperative application. The information provided could enable the surgeon to improve fixation of osteoporotic proximal humerus fractures.

Photofunctionalized Dental Implants: A Case Series in Compromised Bone

Ultraviolet (UV) light treatment of titanium, or photofunctionalization, has been shown to enhance its osteoconductivity in animal and in vitro studies, but its clinical performance has yet to be reported. This clinical case series sought to examine the effect of photofunctionalization on implant success, healing time, osseointegration speed, and peri-implant marginal bone level changes at 1 year after restoration. Four partially edentulous patients were included in the study. Seven implants with identical microroughened surfaces were photofunctionalized with UV light for 15 minutes. Osseointegration speed was calculated by measuring the increase in implant stability quotient (ISQ) per month. Marginal bone levels were evaluated radiographically at crown placement and at 1 year. All implants placed into fresh extraction sockets, vertically augmented bone, simultaneously augmented sinuses, or the site of a failing implant remained functional and healthy at 1 year, even with an earlier loading protocol (2.1 to 4.5 months). ISQs of 48 to 75 at implant placement had increased to 68 to 81 at loading. In particular, implants with low primary stability (initial ISQ < 70) showed large increases in ISQ. The speed of osseointegration of photofunctionalized implants was considerably greater than that of as-received implants documented in the literature. Mean marginal bone levels were -0.35 ± 0.71 mm at crown placement and had significantly increased to 0.16 ± 0.53 mm at 1 year, with coronal gains in marginal bone level that surpassed the implant platform. No implants showed marginal bone loss. Within the limits of this study, photofunctionalization expedited and enhanced osseointegration of commercial dental implants in various clinically challenging/compromised bone conditions. Photofunctionalization resulted in preservation--and often a gain--of marginal bone level, and long-term large-scale clinical validation is warranted.

Implants Inserted with Low Insertion Torque Values for Intraoral Welded Full‐Arch Prosthesis: 1‐Year Follow‐Up

The aim of the present study is to evaluate the osteointegration and crestal bone remodeling after 1 year around implants for intraoral welded immediate full-arch prosthesis inserted with low insertion torque (IT) values. The study was conducted from June 2008 to September 2010. Patients were eligible for the study if they needed an immediate intraoral welded implant-supported full-arch fixed prosthesis and received three or more implants with an IT ≤ 20 Ncm and two or more implants with IT ≥ 25 and ≤ 50. For each implant, peak IT was recorded during insertion surgery; periapical x-rays were taken at the time of surgery and again after 12 months. Finally, it was recorded whether an implant was lost or removed (within 12 months from insertion surgery). Thirteen patients were included in the study; the prosthesis presented the following number of implants: nine with six implants and four with seven implants. A totand al of 82 implants were inserted: 51 implants presented an IT ≤ 20 Ncm (test group), 31 implants presented an IT ≥ 25 and ≤ 50 Ncm (control group). Each prosthesis presented at least three test implants and two control implants. The survival rate after 1 year was 98% for the test and 100% for the control group. The mean distance between the fixture-abutment junction and the bone crest was 0.1 ± 0.8 mm for test and 0.2 ± 0.5 mm for control group at implant insertion. After 12 months, it was 0.7 ± 0.9 mm for test group and 0.8 ± 0.6 mm for control group. The differences were not statistically significant. Within the limitations of this study, the results suggested that rigid framework splinting can be a viable technique to improve success rate of implants with low primary stability using immediate loading protocols for full-arch prosthesis.

Influence on early osseointegration of dental implants installed with two different drilling protocols: a histomorphometric study in rabbit

to evaluate early osseointegration of dental implants installed with two different drilling protocols. thirty-six cylindrical shape Mozo Grau implants, with a diameter of 3.75 and 11 mm long, were placed into the distal condyle (submerged) of each femur of 18 New Zealand rabbits. In the control group, a 3.3 mm diameter drill was used as the last one prior implant installation (standard protocol). In the test group, the same procedure was carried out but an additional 3.5 mm drill was used as the final one (oversized protocol) Thus, we could obtain different primary stability at day 0 between groups. Sacrifice of the animals was after 2, 4 and 8 weeks. Histomorphometric analysis (bone-to-implant contact ratio [BIC%]) and implant stability quotient (ISQ) values (Ostell ) were registered at each sacrifice time. the ISQ values were statistically significant different between groups at day 0 (control: 69.65; test: 64.81); and after 2 weeks (control: 77.93; test: 74). However, after 4 and 8 weeks the results were similar. BIC% showed a similar tendency, with 58.69% for the control group and 40.94% for the test group after 2 weeks, this difference being statistically significant. At 4- and 8-week interval, BIC% was similar. at 2-week interval (early healing), osseointegration had been influenced by different primary stability at implant installation, being slower in the oversized protocol (lower primary stability), which could be especially risky in challenging clinical situations, such as soft bone (class 3 and 4) and early/immediate loading. However, from 4 week on, these differences disappeared. Nevertheless, we have to consider that a direct transfer of the results of this animal study (time bone repair mechanisms) into clinic has to be done with caution.

Arthroscopic reconstruction of the anterior cruciate ligament with paired semitendinosus tendon. Experimental results of a new fixation method

The major problem of reconstructing the anterior cruciate ligament (ACL) with the semitendinosus tendon (STT) is the low primary stability of the STT graft fixation techniques. On 10 cadaver knees a surgical procedure for arthroscopic reconstruction of the ACL with the double looped STT was performed. The femoral attachment was achieved with an "U-formed" tendon wrapped around a bone-plug, which then was blocked in a single-staged femoral bone tunnel. The tibial fixation was attained using a bone-plug and an interference-screw. Anatomic studies were performed on the STT of the cadaver knees. Isometrical determinations were performed intraoperatively for precise anatomical placement of the tendon. We compared these measurements with the postoperative position of the STT-transplant. The tibial and the femoral attachment was tested separately for primary stability and stiffness. The mode of failure of the fixation methods was determined. The average length of the STT was 29.4 cm (SD +/- 3.6 cm, 24-33). With comparing the measured intraoperative and postoperative isometrical values we found a high correlation. The primary stability of the attaching methods in the pullout-testing amounted for the femoral attachment to 448.2 N (SD +/- 76.5 N, 322-560 N) and for the tibial attachment to 440.0 N (SD +/- 72.5 N, 316-538 N). The average stiffness of the femoral fixation was 29.23 N/mm (SD +/- 1.64 N/mm; 26.6-32.1 N/mm). The average stiffness of the tibial fixation measured 28.31 N/mm (SD +/- 1.55 N/mm, 25.1-30.4 N/mm). The presented method provides an economical and easy to perform autologous STT-fixation technique with a high level of primary stability.

In Vitro Stabilizing Effect of a Transforaminal Compared With Two Posterior Lumbar Interbody Fusion Cages

An in vitro biomechanical flexibility test on different lumbar interbody fusion cages using monosegmental lumbar spine specimens. To investigate the stabilizing effect of a transforaminal lumbar interbody fusion (TLIF) cage compared with two established posterior lumbar interbody fusion (PLIF) cages. TLIF using interbody fusion cages is gaining more and more popularity in the treatment of degenerative disc disease. However, only little is known on its biomechanical behavior. Eighteen intact human lumbar spine segments were tested for flexibility in a specially designed spine tester. Pure moments were applied in the three main planes, and range of motion and neutral zone were determined. Then, TLIF using the sickle-shaped MOON cage (AMT AG), PLIF using the cubic Stryker cages (Stryker Orthopaedics), or PLIF using the threaded BAK cages (Zimmer Spinetech) was carried out and the specimens tested again. The stability after implantation of the MOON TLIF cage did not significantly differ from that after implantation of the cubic Stryker PLIF cages (P > 0.05). In contrast, the threaded BAK PLIF cages had a significantly higher primary stability than both the MOON TLIF and the Stryker PLIF cages in lateral bending, flexion, and extension (P < 0.05) but not in axial rotation (P > 0.05). In terms of its stabilizing effect, TLIF using the MOON cage can be recommended as an alternative to PLIF using the cubic Stryker cages. Compared with the threaded BAK PLIF cages, however, the MOON TLIF cage provides a lower primary stability in lateral bending, flexion, and extension.

Monitoring of implant stability in grafted bone using resonance frequency analysisA clinical study from implant placement to 6 months of loading

The aim of this prospective study was to compare implants placed in grafted and normal non-grafted maxilla by means of resonance frequency analysis (RFA), clinical stability and implant failure. Twenty-nine patients with severe atrophy of the edentulous maxilla were treated with autogenous bone grafts as onlay (24 patients) or as interpositional grafts in conjunction with a Le Fort I osteotomy (five patients) 6 months prior to placement of 222 implants. Ten non-grafted patients treated with 75 Brånemark implants in the edentulous maxillae served as a control group. RFA was performed at implant placement, abutment connection and after 6 months of bridge loading. Seventeen (8%) implants were lost in the grafted bone and one (1%) in normal bone. RFA revealed a similar pattern in both grafted and normal maxillae, i.e. increasing resonance frequency (RF) with time (Wilcoxon Signed Rank test for paired data). Twenty implants that were rotation mobile (low primary stability) at the time of insertion showed a significantly lower value at implant placement according to RFA (Mann–Whitney U-test, P=0.020). The RF for the failed implants revealed a tendency towards lower values (Mann–Whitney U-test, P=0.072), compared to the successful implants. It is concluded that implants placed in grafted bone when using a two-stage technique achieve a stability similar to that of implants placed in normal non-grafted bone.

Monitoring of implant stability in grafted bone using resonance frequency analysis: A clinical study from implant placement to 6 months of loading

The aim of this prospective study was to compare implants placed in grafted and normal non-grafted maxilla by means of resonance frequency analysis (RFA), clinical stability and implant failure. Twenty-nine patients with severe atrophy of the edentulous maxilla were treated with autogenous bone grafts as onlay (24 patients) or as interpositional grafts in conjunction with a Le Fort I osteotomy (five patients) 6 months prior to placement of 222 implants. Ten non-grafted patients treated with 75 Brånemark implants in the edentulous maxillae served as a control group. RFA was performed at implant placement, abutment connection and after 6 months of bridge loading. Seventeen (8%) implants were lost in the grafted bone and one (1%) in normal bone. RFA revealed a similar pattern in both grafted and normal maxillae, i.e. increasing resonance frequency (RF) with time (Wilcoxon Signed Rank test for paired data). Twenty implants that were rotation mobile (low primary stability) at the time of insertion showed a significantly lower value at implant placement according to RFA (Mann–Whitney U-test, P=0.020). The RF for the failed implants revealed a tendency towards lower values (Mann–Whitney U-test, P=0.072), compared to the successful implants. It is concluded that implants placed in grafted bone when using a two-stage technique achieve a stability similar to that of implants placed in normal non-grafted bone.