Resonance frequency analysis of one-stage dental implant stability during the osseointegration period.

BACKGROUND: Currently, there is no available clinical tool to evaluate the amount of osseointegration and stability around dental implants. It has been recently suggested that changes in the stiffness of an implant in bone during healing may be monitored by using resonance frequency analysis (RFA). The aim of this study was to determine whether RFA can be integrated into the routine clinical evaluation of initial healing of dental implants. METHODS: Thirty-one patients (18 female and 13 male; mean age of 51.7 years) were included into this study. A total of 122 implants and three different, but comparable, implant designs were evaluated by using RFA. The specific transducer for each implant system was used. ISQ (implant stability quotient) readings were obtained for each implant at the time of surgery, 3 and 6 weeks postoperatively, and at the time of loading (3 or 6 months following surgery). Data were analyzed for different healing times, various anatomical locations, implant length, and type. Average time in function was 12 months. RESULTS: Two implants failed during healing. Implant stability was higher on the mandible compared to the maxilla for each implant system studied (Mann-Whitney test, P <0.01). ISQ readings decreased significantly at 3 and 6 weeks post-surgery compared to readings obtained at surgery (Wilcoxon matched pairs sign-rank tests, P <0.01). A recovery to the initial ISQ levels was noted at the time of implant loading. The possible effects of different types and lengths of implants to ISQ readings were examined. CONCLUSIONS: Results of this study support the need for a clinical tool to evaluate dental implant stability prior to loading, especially for implants placed in the maxilla. It appears that implant stability is weakest at 3 to 6 weeks in one-stage non-loaded dental implants. ISQ readings can be used to determine different healing phases and the stability of dental implants. However, it is difficult to define a general standardized range of ISQ readings for successful implant integration for various implant systems. Thus, RFA values/ISQ levels should be calibrated for each implant system separately. Further studies are needed to compare the early changes seen in immediately loaded dental implants and to determine whether there is any time in which the total recovery in ISQ levels may occur.

Radiographic evaluation of dental implants placed using an osteotome technique.

BACKGROUND: The osteotome technique has been successfully used for implant placement when a limited vertical height is available at posterior maxilla. However, it is not clear if new bone is formed at the apical portion of the implant placed by this technique without any bone graft. The aim of this study was to radiographically evaluate bone formation around dental implant surfaces exposed to the space created at the sinus floor without the presence of any graft material. METHODS: Forty patients (21 male, 19 female; mean age 46.7 years) who received a total of 75 dental implants together with indirect sinus lifting procedure were included. Initial and 6-month postoperative panoramic films were scanned and analyzed using a commercially available software program. Implants were divided into two groups: initial alveolar bone height <9 mm or > or =9 mm. This helped determine the effect of available bone and exposed implant surface on bone formation in a system where the shortest implant was 8 mm. RESULTS: The mean implant length placed at locations with <9 mm initial bone height (mean 7 +/- 1.3 mm, N = 29 implants) was 11 +/- 1.7 mm; gain in bone height was 3.9 +/- 1.9 mm. At locations where minimum bone height was 9 mm (mean 10.4 +/- 0.7 mm), 44 implants were placed with a 13.5 +/- 1.06 mm mean length. Mean gain in bone height was 2.9 +/- 1.2 mm at these sites. Two implants were lost at stage 2 surgery. The success rate after 25 months of loading was 97.3%. CONCLUSIONS: It is possible to radiographically observe a gain of approximately 3 to 4 mm of bone from the sinus floor to the implant apex. The amount of initial alveolar bone height, presence of sinus membrane perforation, and the amount of exposed implant surface appear to play a role in the presence or absence of radiopacity within the elevated sinus floor, following 6 months of healing.

Histological and clinical evaluation of 3 different grafting materials for sinus lifting procedure based on 8 cases.

BACKGROUND: The reconstruction of edentulous patients with adequate bone volume and density by using dental implants has become a viable treatment option with high predictability. However, initial stabilization is difficult to achieve in the posterior maxillary regions where cortical bone is thin or absent due to severely resorbed alveolar ridges. Maxillary sinus lift procedures applied with various grafting materials enable clinicians to place implant-supported prostheses even in cases with increased pneumatization of the maxillary sinus. METHODS: The purpose of this study was to evaluate histologically and clinically different grafting materials used in maxillary sinus floor augmentation. Deproteinized bovine bone granules (DBBG), demineralized freeze-dried bone powder (DFBP), and porous hydroxyapatite (PHA) were used as grafting materials. A total of 19 implants in 8 patients were placed into grafted sites. In 3 patients, a 2-stage approach was used wherein implants were inserted after a 6-month healing period following a sinus lift procedure. Specimens were taken with a trephine drill, and the site of the specimen was enlarged to accept an implant. For the remaining cases, a 1-stage approach, which included sinus lifting and implant placement, was used and bone biopsies were taken during the uncovering stage. After 6 months of healing, fixed prosthetic restorations were fabricated. RESULTS: The healing period progressed without any complications, and all implants were loaded. The mean functioning time was 12 months, varying from 9 to 24 months. CONCLUSION: The results indicate that DFBP resorbs earlier than PHA and DBBG in sinus lift procedures.

Histologic and histomorphometric comparison of immediately placed hydroxyapatite-coated and titanium plasma-sprayed implants: a pilot study in dogs.

The purpose of this pilot study was to make a histologic and histomorphometric comparison of hydroxyapatite-(HA) coated and titanium plasma-sprayed (TPS) root-form implants that were placed in 2 mongrel dogs immediately after extraction of mandibular premolars. After 8 weeks of healing, the implant-containing segments of the mandible were removed en bloc and bone blocks including implants were sectioned. Histologic and histomorphometric analyses were performed by evaluating bone sections. The mean bone contact percentage of HA-coated implants was 61.84 +/- 7.84%, with a range of 52.09% to 75.7%, and the mean bone contact percentage of TPS implants was 51.35 +/- 12.1%, with a range of 30.1% to 70.6%. This pilot study suggests that HA-coated implants placed into fresh extraction sockets can achieve better bone contact than TPS implants, but there was evidence that the surface of the HA layer can be resorbed, so long-term stability of HA coatings in immediate implantation must be investigated.