The International Journal of Oral & Maxillofacial Implants, 04/2007

Purpose: The aim of this study was to compare, through histomorphometric analysis, the use of donor autogenous bone graft from calvarial or iliac sources for maxillary sinus lift procedures. Materials and Methods: Sixteen patients requiring maxillary sinus augmentation were included in this study. One group of 10 patients was alternatively selected to receive autologous calvarial bone particles, and another group of 6 patients received autologous iliac bone particles. Five months after surgery, bone biopsy specimens were obtained at the time of implant procedure and analyzed through histomorphometry. To compare mean values between the calvarial and iliac crest groups, the Student t test was performed. The level for statistical significance was set at P .05. Results: All patients completed the healing period following sinus augmentation procedure without complications. In the calvarial group, an average total bone volume (BV) of 73.4% ± 13.1% was found. Nonvital bone constituted an average of 5.5% ± 6.3% of the total tissue volume. The percentage of vital bone (VB) showed an average of 67.9% ± 16.1%. In the iliac group, the average total bone volume was 46.6% ± 17.4%, with an average of 12.6% ± 7.7% of NVB and an average of 34.0% ± 21.5% of VB. A significant difference was observed between calvarial and iliac bone grafts with respect to BV, VB, and NVB (P .05). Conclusion: From this present histomorphologic study, it might be concluded that grafted bone obtained from calvarial sources for sinus lift procedure presented a significantly higher degree of bone volume and vital bone volume in contrast to bone harvested from the iliac crest. Schlagwörter: autogenous bone, bone regeneration, maxillary sinus augmentation

Purpose: One strategy to improve implant osseointegration is to control the quality of the bone reaction at the implant-bone tissue interface using an implant coated with biologically active substances. The purpose of this study was to investigate the effect of a tetra-cell adhesion molecule (T-CAM) coating composed of 4 cell-adhesion molecules-an arginine-glycine-aspartic acid (RGD) sequence, a proline-histidine-serine-arginine-asparagine (PHSRN) sequence, a tyrosine-histidine sequence (YH), and a glutamic acid-proline-aspartic acid-isoleucine-methionine (EPDIM)-on the rough-surfaced titanium implant on peri-implant bone formation in the rabbit femur with poor local bone conditions and minimal primary stability. Materials and Methods: Seven T-CAM-coated (blasted/T-CAM) and uncoated (blasted) implants with a rough surface (hydroxyapatite-blasted; Ra = 1.8 µm) were placed in slightly oversized beds of the metaphyses of the right and left femurs of 7 New Zealand White rabbits with light tactile pressure, and minimal primary stability was obtained. To evaluate the effects of T-CAM coating on the peri-implant bone healing response, histomorphometric analysis was performed 8 weeks after surgery. The 2 groups were compared using the Student t test, with a significance level of P .05. Results: Compared to uncoated blasted implants at 8 weeks of healing, the blasted/T-CAM implants showed a significantly greater amount of bone-implant contact (BIC; P .01) and new bone formation in the zones 0 to 100 µm and 0 to 500 µm lateral to the implant surface (P .05) in the medullary space. Conclusion: The T-CAM coating on the rough-surfaced titanium implants significantly enhanced peri-implant bone formation in rabbit femurs with poor local bone condition. (More than 50 references) Schlagwörter: cell adhesion molecule, dental implants, osseointegration, poor bone quality, rough surface, titanium

Purpose: To investigate the effects of different chemically modified titanium surfaces on protein adsorption and the osteoblastic differentiation of human embryonic palatal mesenchymal (HEPM) cells. Materials and Methods: Three different surfaces were evaluated. The first, a machined surface (Ti-M), was considered a control. The second surface was acid etched (Ti-AE). The third surface was prepared by exposing the Ti-AE samples to sodium hydroxide (NaOH) solution (Ti-AAE). The surface characteristics of chemically modified titanium were investigated by means of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and profilometry. To evaluate the production of biomarkers, commercial kits were utilized. Results: Surface composition and morphology affected the kinetics of protein adsorption. Ti-AE surfaces manifested a greater affinity for fibronectin adsorption compared to Ti-M or Ti-AAE surfaces. It was observed that Ti-AE and Ti-AAE surfaces promoted significantly greater cell attachment compared to Ti-M surfaces. Statistically significant differences were also observed in the expression of alkaline phosphatase (ALP) activity, osteocalcin, and osteopontin on all 3 titanium surfaces. ALP activity and osteocalcin production up to day 12 suggested that differentiation of the cells into osteoblasts had occurred and that cells were expressing a bone-forming phenotype. Conclusions: It was thus concluded from this study that surface morphology and composition play a critical role in enhancing HEPM cell proliferation and differentiation into osteoblast cells. (More than 50 references) Schlagwörter: cell attachment, cell proliferation, differentiation and mineralization, fibronectin, osteoblast precursor cells, protein adsorption

Purpose: Stress analysis was performed for various implant designs using 3-dimensional finite element analysis approaches. Materials and Methods: Six implant designs were included: 3 parallel-sided implants (no thread, triangular thread, and squared thread), 2 stepped configurations (nonthread and triangular thread), and a tapered body of implant with squared thread. All threads had spiral characteristics. The mandibular model was constructed from computed tomographic (CT) images of a human mandible, and the material properties were anisotropic (different in different directions). A 100-N oblique force was applied at a 45-degree angle to the long axis of the implants at the buccal cusp as the loading condition. Results: Compared with cylindric implants, threaded implants (either triangular or squared) demonstrated increased peak stress at the crestal bone. The bone stress of stepped implants was decreased in the cortical region but was increased in the trabecular region. However, both threaded and stepped designs showed decreased interfacial stresses of bone near the valleys of the threaded and stepped areas. The tapered design decreased stresses by up to 32% in the cortical region and 17% in the trabecular region. Conclusions: Although threaded implants could not decrease the peak stress at the crestal bone, both threaded and stepped designs show an ability to dissipate the interfacial stresses of bone. The use of tapered implants could reduce peak stress in both cortical and trabecular bone. Schlagwörter: finite element analysis, implant designs, threads

Purpose: The aim of this study was to evaluate whether local application of platelet-rich plasma (PRP) would induce bone regeneration in cranial defects on rabbits. Materials and Methods: Twelve female New Zealand rabbits were used for this study. Two identical 10-mm-diameter bicortical cranial defects were created in each animal. One of the defects was grafted with PRP, while the contralateral was left unfilled as a negative control. Animals were sacrificed at 2, 4, 6, and 8 weeks after surgery, and biopsy specimens were evaluated histologically and histomorphometrically under light microscopy. Analysis of variance was used for statistical analysis. Results: The histomorphometric evaluation showed more regenerated bone after local administration of PRP at 2 weeks (P > .05), 4 weeks (P .05), and 6 weeks (P > .05). At week 8, new bone formation was comparable in both groups. Conclusion: In this animal model, local application of PRP in bone defects enhances healing significantly at 4 weeks. Schlagwörter: bone regeneration, platelet-rich plasma, rabbits

Purpose: To investigate the effects of thermal cycling and surface roughness of metal implant abutments and the intaglio surface of the copings on the retentive properties of 4 provisional luting agents commonly used in the cementation of implant-retained fixed partial dentures (FPDs). Materials and Methods: A 2-unit implant-retained FPD and a 4-unit implant-retained FPD were fabricated using gold-palladium alloy. The abutments used were 5 mm in height. The FPDs were cemented with 4 commonly used provisional luting agents and thermocycled for 700 cycles from 5°C to 36°C to 55°C and were then subjected to tensile strength testing. After thermal cycling, the intaglio surfaces of the same FPDs and the abutments were air-abraded with 50 µm Al2O3 particles. FPDs were cemented using the same provisional cements, and after 24 hours of storage in 100% humidity, tensile strength tests were performed. Descriptive statistics, 2-way analysis of variance, Friedman's 2-way ANOVA, and Tukey's HSD test (a = .05) were performed. Results: Both thermal cycling and air abrasion had a significant effect (P .001) on the retentive values of all cements tested. A noneugenol provisional cement (Nogenol) exhibited the lowest mean retentive value after both thermal cycling and air abrasion for both the 2-and 4-unit FPD models. The urethane resin provisional cement (Improv) exhibited the highest mean retentive strength for both the 2- and 4-unit FPDs after thermal cycling and air abrasion treatments. Conclusions: Thermal cycling had a detrimental effect on the retentive properties of all cements tested. Air abrasion significantly improved the cement failure loads of the provisional luting agents used in the study and seems to be an effective way of increasing the retention of implant-retained FPDs. Schlagwörter: air abrasion, dental cements, implant-supported prostheses, thermal cycling

Purpose: Misfit of implant components has been linked to restorative complications such as screw loosening. Although previous studies have shown a correlation between rotational misfit and screw loosening, the impact of casting procedures on rotational misfit is lacking. The aim of this in vitro study was to evaluate the effect of casting procedures on rotational misfit of cast abutments when compared to machined titanium abutments. Materials and Methods: Forty-eight external hexagonal implants and 48 abutments were placed in 4 groups of 12 samples each: (1) machined titanium abutments, (2) premachined palladium abutments cast-on with palladium, (3) plastic burnout abutments cast with nickel chromium, and (4) plastic burnout abutments cast with cobalt chromium. Rotational misfit between the external hexagon of the implant and the internal hexagon of the abutment was measured using standardized techniques and recorded in degrees. Mean values for each group were analyzed with analysis of variance and Tukey test. Results: The mean rotational misfit was 1.21 ± 0.57 degrees for machined titanium abutments, 1.77 ± 130 degrees for cast-on abutments, 1.98 ± 0.72 degrees for cast NiCr abutments, and 2.79 ± 1.13 degrees for cast CoCr abutments. Significantly greater rotational misfit was recorded with cast CoCr abutments when compared to machined titanium abutments (P .05). Conclusion: Rotational misfit was less than 2 degrees for all groups except for cast CoCr abutments, which demonstrated a significantly greater rotational misfit. Schlagwörter: abutments, implants, misfit, rotational misfit

Purpose: To report on the implant outcome of delayed, early, and immediate loading of implants in the edentulous mandible in a prospective controlled study. Materials and Methods: On a consecutive basis, the first 10 patients received an overdenture retained by 2 ball attachments 4 months after implant insertion (delayed), and the next 10 patients received an overdenture 1 week after implant surgery (early). The next 10 patients were treated with a fixed prosthesis on 3 implants (Brånemark Novum) either the day of or the day after surgery (immediate). All patients were followed for 1 year; half were followed for 2 years. Measures of assessment for this prospective clinical trial included monitoring of loading at prosthesis level (bite fork) as well as at the abutment level (strain gauges), 3-dimensional imaging of marginal bone remodeling, and implant stability. Results and Discussion: One patient in each OD group lost both implants. The losses occurred 6 months after loading in the delayed group and 1 month after loading in the early group. In the immediate group, 1 patient lost both distal implants 5 months after loading. In 2 other patients, 1 distal implant failed after 1 year of loading. Maximal bite forces increased over time for all groups. Marginal bone loss was the highest for the immediate group, while no differences in implants stability were observed between the 3 groups after 1 year of loading. Conclusions: According to this prospective controlled clinical trial, the results achieved with implants loaded early were comparable to those achieved with implants loaded after a delay. Distal implants are at higher risk for failure in the immediate loaded protocol. (Clinical Trial) Schlagwörter: early loading, immediate loading, occlusal bite forces, 3D imaging of bone remodeling

Purpose: This study investigates the pre- and posttreatment morphology of the mucosa around immediately loaded implants in the edentulous maxilla. Materials and Methods: Implants were placed and immediately loaded in edentulous maxillae; pre- and posttreatment impressions were obtained. The resulting casts were digitalized into 3-dimensional images, and the pre- and posttreatment images were superimposed. The width and height of the maxillary alveolar process were measured at central and interproximal implant sites in a vertical section of the superimposed holograms. For statistical analysis, the Delta value (d) was defined as the difference between the pre- and posttreatment images for all measurements. Results: Sixty-seven Straumann implants placed in 9 patients and immediately restored with provisional fixed restorations were analyzed. An increase in width at all measurement sites was observed after treatment. Width increased for both central implant (1.51 ± 1.16 mm, P .001) and interproximal implant sections (1.02 ± 1.21 mm, P .001). Mean d for height was found to be decreased at central implant sites (-1.21 ± 1.67 mm, P = .012) and at interproximal sections (-0.72 ± 1.68 mm, P = .098). Discussion and Conclusion: Clinically, it has been observed that the placement of an immediate provisional affects the peri-implant tissue morphology according to its emergence profile. The result after treatment was a wider contour of the peri-implant soft tissue, located in a more apical position than the original mucosal level. The most coronal part of the papillalike mucosa at interproximal sites would be nearest to the original mucosal level before treatment. The scalloped mucosal configuration obtained was consistent along the rehabilitated arch. Statistically significant dimensional changes of the peri-implant mucosa were observed with an immediate loading approach. (Clinical Trial) Schlagwörter: dental implants, edentulous maxilla, immediate loading, papilla-like mucosa, peri-implant soft tissue, scalloped mucosa, screw-retained provisional prostheses

Purpose: The aim of this study was to analyze the survival rate of endosseous implants placed in the partially dentate maxilla treated with sinus inlay block bone grafts. Materials and Methods: Seventeen patients were subjected to bone augmentation procedures prior to or in conjunction with implant placement. Bone volumes were regarded as insufficient for implant treatment unless a bone grafting procedure was performed. The patients were treated with sinus inlay block bone grafts and endosseous implants in a 1- or 2-stage procedure. A total of 69 implants were placed in the patients who were followed for 29 to 101 months (mean, 53.1 months). The retrospective patient group was also prospectively followed using a standardized clinical and radiographic study design. Results: The implant survival rate was 91.3% (63/69). All implants were lost during the period from abutment connection to connection of the definitive prosthesis. All bone grafts were stable. Bone grafts supported 48 implants, of which 5 failed (10.4%). In the residual bone, 21 implants were placed, of which 1 failed (4.8%). All patients received a fixed partial prosthesis, which was stable during the follow-up period. Conclusion: The results of this investigation revealed a satisfactory clinical outcome of implant placement in grafted partially dentate maxillae after a mean follow-up of 53.1 months. Schlagwörter: bone augmentation, bone graft, dental implants, endosseous implants, maxillary sinus, partially dentate maxillae

Purpose: This anatomic study was undertaken to examine the effects of atrophy on bone quantity and quality in the mandibular interforaminal region. Materials and Methods: Three sections were made from each jaw studied, and each section was measured by means of a morphometric software program (Artma-Biomed, Vienna, Austria). The mandibular specimens were grouped according to the classification of Cawood and Howell and also according to that of Lekholm and Zarb. Results: The macromorphometric measurements revealed that mandibular atrophy may cause the loss of up to 60% of the original bone mass. As the maximum width remained relatively consistent in all jaw sections, it can be assumed that the reduction in total area of each jaw section results from a reduction in mandibular height. The compact and cancellous bone portions were equally affected by resorption. The assessment of bone quality showed that most mandibles displayed a thick cortical compartment, especially inferiorly and lingually, with variations in the amount of cancellous bone. There was a clear predominance of bone types 2 and 3. Discussion and Conclusion: The interforaminal region of the mandible appears to be the site of choice for implantation, since it can be expected that the bone structure is well suited to provide the necessary stability even in severely atrophic mandibles. As the degree of alveolar ridge resorption does not depend on the patient's age but on the time elapsing postextraction, implants should be placed as soon as possible after tooth loss in order to avoid excessive resorption. Schlagwörter: atrophy, bone density, cancellous bone, compact bone, interforaminal region, mandible, residual ridge resorption

Purpose: Oral malignancy is often treated with a combination of surgery and radiation therapy (RT). The aim of this systematic review was to examine the effects of pre- and postimplantation RT on dental implant failure. Materials and Methods: The literature published from 1990 through 2006 was reviewed for studies assessing pre- and postimplantation RT. Potential studies were identified by searches of PubMed, SCIRUS, and the Cochrane Central Register of Controlled Trials (CENTRAL). The incidence of implant failure has been linked to the following variables: post- versus preimplantation RT, site of implant placement, RT dose, delay from RT to implant placement, and timing of implant failure after placement. Results: Similar failure rates were found for implants placed post-RT compared to those placed pre-RT (3.2% and 5.4%). In preimplantation RT, the implant failure rate was lower for the mandible (4.4%) in comparison to the maxilla (17.5%; OR = 4.63; 95% CI: 2.25 to 9.49). Other results did not reach statistical significance. No failures were observed in association with an RT dose lower than 45 Gy. All implant failures observed occurred within 36 months after RT, and most occurred between 1 and 12 months after placement. Conclusion: Notwithstanding the low number of implants evaluated, this review showed similar failure rate for implants placed post-RT and those placed pre-RT (3.2% and 5.4%, respectively). (Systematic Review) Schlagwörter: dental implants, oral cancer, radiation therapy

Purpose: To evaluate the changes in stability of immediately placed implants over a 6-month healing period relative to implants placed in native bone and to compare the stability of 2 different implant designs when placed as immediate implants in extraction sites. Materials and Methods: This prospective cohort study evaluated 3 implant patient populations. The control group (9 patients, 11 implants) required a single-stage, 1-piece, rough-surface implant (considered a "standard" implant) placed in nongrafted sites at least 6 months postextraction. The 2 experimental groups (25 patients, 28 implants) required extraction and immediate placement of either standard implants (12 patients) or tapered, self-tapping implants (13 patients). Immediate implant placement was carried out at the time of tooth extraction. Resonance frequency analysis (RFA), a measure of implant stability, was performed following implant placement at 2- to 4-week intervals for the first 16 weeks and at 24 weeks for immediate implants. Results: Placement protocol (control versus immediate placement) resulted in significant (P .001) differences in implant stability, even though there was no difference (P > .90) in initial, mechanical implant stability between these groups. The immediately placed implants had significantly greater reductions in stability, approximately 15%, from baseline to 4 weeks. Immediate implant stability was consistent with that of implants placed in native bone after 12 to 16 weeks. Implant design did not have a significant effect on stability. Conclusions: This study demonstrates that immediate placement protocols are viable options and that standard-design implants may provide levels of biologic stability similar to a tapered, self-tapping implant design in immediate placement protocols. Most importantly, this study documents high levels of metabolic activity in the supporting osseous tissue following immediate placement, which may extend time to restoration compared with traditional implant placement. (Clinical Trial) Schlagwörter: dental implants, implant stability, resonance frequency analysis, tooth extraction

Purpose: The aim of this study was to evaluate the 3-year success rates of wide-body implants with a regular- or wide-neck configuration and a sandblasted, large grit, acid-etched (SLA) surface. Materials and Methods: A total of 151 implants were consecutively placed in posterior sites of 116 partially edentulous patients in a referral clinic at the School of Dental Medicine, University of Bern. All implants were restored with cemented crowns or fixed partial dentures after a healing period of 6 to 8 weeks (for implants placed without simultaneous bone augmentation) or 10 to 14 weeks (for implants with simultaneous bone augmentation). All patients were recalled 36 months following implant placement for a clinical and radiographic examination. Results: One implant failed to integrate during healing, and 11 implants were lost to follow-up and considered dropouts. The remaining 139 implants showed favorable clinical and radiographic findings and were considered successfully integrated at the 3-year examination. This resulted in a 3-year success rate of 99.3%. Radiographic evaluation of 134 implants indicated stability of the crestal bone levels: During the study period, the crestal bone level changed less than 0.5 mm for 129 implants. Conclusion: Successful tissue integration was achieved with wide-body implants with a regular or a wide-neck configuration and an SLA surface with high predictability. This successful tissue integration was well maintained for up to 3 years of follow-up. (Case Series) (More than 50 references) Schlagwörter: clinical trials, dental implants, wide-body implants, wide-neck implants

Purpose: The aims of this study were to assess the treatment outcome of immediately loaded full-arch screw-retained prostheses with distal extensions supported by both upright and tilted implants for the rehabilitation of edentulous jaws and to compare the outcomes of upright versus tilted implants. Materials and Methods: At 4 study centers, 342 Osseotite NT implants were consecutively placed in 65 patients (96 implants were placed in 24 mandibles and 246 implants in 41 maxillae). The 2 distal implants were tilted by 25 to 35 degrees. Provisional full-arch restorations made of a titanium framework and acrylic resin teeth were delivered within 48 hours of surgery and immediately loaded. The final prosthesis was delivered after 3 months of healing. Results: Three implants failed during the first year and another 2 within 18 months of loading in the maxilla. The cumulative implant survival rate for the maxilla was 97.59% for up to 40 months of follow-up. No implant failure was recorded for the mandible. The prosthetic success rate was 100%. Marginal bone loss around upright and tilted implants was similar. Patients were satisfied of their esthetics, phonetics, and function. Conclusion: The preliminary results of this study suggest that immediate rehabilitation of the edentulous maxilla and mandible by a hybrid prosthesis supported by 6 or 4 implants, respectively, may represent a viable treatment alternative with respect to more demanding surgical procedures. The clinical results indicate that immediately loaded tilted implants may achieve the same outcome as upright implants in both jaws. (Clinical Trial) Schlagwörter: dental implants, edentulous jaw, immediate loading, tilted implants

Purpose: The purpose of this article is to describe the management of patients with extreme maxillary atrophy. Their treatment consisted of maxillary fixed prostheses supported by conventional implants placed in residual anatomic structures in conjunction with zygomatic implants positioned using the sinus slot technique of Stella and Warner. Materials and Methods: A retrospective chart review was conducted of all patients who received zygomatic implants between January 2000 and January 2005. The preoperative evaluations included panoramic digital radiographs and computed tomographic scan to identify the anatomic structures and detect the presence of pathology. All intra- and postoperative complications were recorded. Screw-fixed restorations were placed 4 to 6 months after implant placement. After prosthetic restoration, all patients received a minimum of 12 months' follow-up. Results: Twenty-one patients (11 women and 10 men) with severe maxillary atrophy underwent treatment with zygomatic implants placed using the sinus slot technique. Mean patient age was 54.1 years (range, 31 to 75 years). One patient presented with ectodermal dysplasia. A total of 89 conventional implants and 40 zygomatic implants were placed. During surgery, the sinus membrane was perforated in all cases; however, there were no significant postoperative complications. One patient presented with an ecchymosis. Two conventional implants failed; none of the 40 zygomatic implants failed. Mean follow-up after placement of the implants was 29 months, during which time the prostheses and implants remained stable and functional. Conclusion: Zygomatic implants, when positioned in conjunction with premaxillary implants, can facilitate the surgical rehabilitation of patients presenting with severe maxillary resorption, as an alternative to bone grafting. (Case Series) Schlagwörter: atrophic maxilla, dental implants, sinus slot technique, zygomatic implants

Purpose: The use of endosseous implants in the prosthetic restoration of edentulous patients with recessive dystrophic epidermolysis bullosa (RDEB) may provide improved outcomes when compared with traditional prosthetic methods. The aim of this study was to evaluate the feasibility of placing endosseous implants in patients with RDEB and to compare the treatment outcomes of fixed and removable implant-supported restorations in the edentulous maxilla or mandible with the main emphasis on patient response. Materials and Methods: Six patients with RDEB were treated with implants. All patients were completely edentulous in either the maxilla or mandible and had marked oral involvement, with alterations in the soft and hard tissues in all cases. Three patients were treated with fixed, screw-retained implant-supported prostheses, and 3 were treated with removable implant-supported prostheses. Six months after prosthetic restoration, patients were given a questionnaire to assess their psychologic well-being and satisfaction with the implant-supported restoration marked on a visual analog scale. Results: A total of 38 dental implants (21 maxillary, 17 mandibular) were placed in 6 patients. The implant success rate was 97.9%. The average follow-up from implant placement was 5.5 years (range, 1 to 9). The fixed and removable implant-supported prostheses were associated with improvements in comfort and retention, function, esthetics and appearance, taste, speech, and self-esteem. The level of satisfaction was slightly higher in patients with a fixed prosthesis. Conclusion: These findings suggest that endosseous implants can be successfully placed and provide support for prostheses in patients with RDEB. Patients with fixed prostheses and overdentures were satisfied with their implant-supported prostheses in the edentulous maxilla and mandible. (Case Series) Schlagwörter: dental implants, epidermolysis bullosa

Purpose: To evaluate the combination of surgical-grade calcium sulfate (SGCS) and platelet-rich plasma (PRP) for alveolar ridge preservation prior to implant placement. Materials and Methods: Five mongrel dogs were used as subjects. Four enlarged mandibular extraction sockets, 2 on each side, were created in each dog. According to a split-mouth design, the 2 anterior sockets received either SGCS/PRP (SGCS/PRPant) or were left unfilled, while the 2 posterior sockets received either SGCS/PRP (SGCS/PRPpost) or SGCS. Computerized tomographic (CT) scans were conducted at 1 day and 8 weeks postextraction to detect the change in ridge height. Bone scintigraphy was performed at 2, 4, and 6 weeks to investigate new bone formation activity. At 8 weeks, 1 dog was sacrificed for histologic and histomorphometric study. Meanwhile, implants were placed in the remaining 4 dogs. These 4 dogs were sacrificed after 3 months. Results: Less ridge resorption was observed in the anterior SGCS/PRP-filled sites compared to unfilled sites (P = .001), while no significant difference was found between the SGCS/PRPpost and SGCS groups (P = .544). Bone scintigraphy showed that sites filled with SGCS/PRP showed significantly higher count/pixel at 2 (P = .028), 4 (P = .009), and 6 weeks (P = .037) than the unfilled sites. Nevertheless, the SGCS/PRPpost group achieved significantly higher values than the SGSC group only at 2 weeks (P = .036). Histomorphometrically, the SGCS/PRPant group showed a significantly higher percentage of bone-implant contact than the unfilled group (P = .024), but no significant difference was detected between the SGCS/PRPpost and SGCS groups (P = .979). Conclusion: Grafting SGCS/PRP in fresh extraction sockets reduced alveolar ridge resorption and promoted the bone formation in this canine model. The addition of PRP to SGCS resulted in the enhancement of bone regeneration in the early phase of healing. (Pilot Clinical Trial) (More than 50 references) Schlagwörter: alveolar ridge preservation, calcium sulfate, dental implants, platelet-rich plasma, Tc-99m-MDP