The International Journal of Oral & Maxillofacial Implants, 01/2003

Purpose: In the present study the time course of local bone formation following the application of PRP during implant placement was evaluated histomorphometrically and histologically. Materials and Methods: The mandibular premolars of 12 adult minipigs were removed surgically and 72 sites were prepared for implant placement. Before the implants (MK III, Replace, and MK III TiUnite) were placed, autogenous PRP (8×10⁵; to 10×10⁵ platelets/µL) was instilled into the host sites on the left side. The animals were sacrificed at 3, 6, and 12 weeks, and undecalcified ground sections were prepared. Results: The histomorphometric evaluation showed significantly more bone-to-implant contact after topical PRP application in the early healing phase (6 weeks), which varied as a function of the distance from the implant surface (controls = 24.2% versus PRP = 44.21%; P = .013). At 12 weeks, the extent of osteoneogenesis was comparable in the 2 groups (controls = 51.3% versus PRP = 44.2%; P = .251). Statistical analysis revealed no significant interaction between implant surface type and PRP. Discussion: Topical PRP application significantly increased the activity of bone regeneration at implant host sites during early healing. Conclusion: In the present study PRP was found to have a time- and sitedependent effect on peri-implant bone healing.

Purpose: This study was undertaken to evaluate clinically, histologically, and immunohistochemically the use of a new porous hydroxyapatite (HA) (B. Agra, Cabon, Milan, Italy) as a grafting material for maxillary sinus augmentation with simultaneous implant placement. Materials and Methods: A total of 28 titanium implants were placed in 12 patients with an average of 4.5 mm of bone on the sinus floor. HA granules were packed around the implants in the sinus cavity. After a healing period of 5 to 6 months, second-stage surgery was carried out. In 5 patients, bone cores were harvested from grafted areas and processed for histology and immunocytochemistry. Results: All implants were clinically stable at second-stage surgery and were followed for an average of 3 years. The histology showed newly formed bone in direct contact with the HA granules. Immunohistochemistry showed the presence of large quantities of bone sialoprotein and osteopontin in and around the granules of HA. Discussion and Conclusion: This study suggests that a new porous HA accommodated sinus floor augmentation in patients with 3 to 5 mm of bone height preoperatively. By possibly attracting circulating biocomponents at sites of tissue repair, it may promote bone regeneration.

Purpose: This 1-year prospective study evaluated the implant success rate, peri-implant tissue response, and esthetic outcome of immediately placed and provisionalized maxillary anterior single implants. Materials and Methods: Thirty-five patients (8 men, 27 women) with a mean age of 36.5 years (range 18 to 65) were included in this study. Thirty-five threaded, hydroxyapatite-coated implants were placed and provisionalized immediately after each failing tooth had been removed. The definitive restoration was placed 6 months later. The patients were evaluated clinically and radiographically at implant placement and at 3, 6, and 12 months after implant placement. Results: At 12 months, all implants remained osseointegrated. The mean marginal bone change from the time of implant placement to 12 months was -0.26 ± 0.40 mm mesially and -0.22 ± 0.28 mm distally. No significant differences in the Plaque Index scores were noted at different time intervals. The mean midfacial gingival level and mesial and distal papilla level changes from pretreatment to 12 months were -0.55 ± 0.53 mm, -0.53 ± 0.39 mm, and -0.39 ± 0.40 mm, respectively. All patients were very satisfied with the esthetic outcome and none had noticed any changes at the gingival level. Discussion: Although marginal bone and gingival level changes were statistically significant from pretreatment to 12 months of follow-up, they were well within clinical expectations. Conclusion: The results of this study suggest that favorable implant success rates, peri-implant tissue responses, and esthetic outcomes can be achieved with immediately placed and provisionalized maxillary anterior single implants.

Purpose: To analyze the surface composition of 34 different commercially available titanium dental implants. Materials and Methods: Surface composition was evaluated by x-ray photoelectron spectroscopy (XPS). Samples were divided into 4 groups, depending on their surface topography (machined, sandblasted, acid etched, or plasma sprayed). Results: Statistical analysis of the data showed a clear relationship between surface composition and topography, which can be easily accounted for by the chemical effects of the surface treatment performed. On average, acid-etched and plasma-sprayed surfaces had higher titanium and lower carbon concentration than machined surfaces. Discussion and Conclusion: Current studies aimed at the evaluation of implants with different topography should not implicitly assume that topography is the only variable controlling the biologic response. Rather, when comparing different topographies, it should be taken into account that surface chemistry may be a variable as well.

Purpose: To determine, in vitro, cytotoxicity and cell adhesion on 3 different implant surfaces. Materials and Methods: All samples had machined surfaces, but they were subjected to different cleaning procedures, which produced 3 different surface chemistries. One of the samples was "as-produced" from the machining tools. The other samples were subjected to partial and total cleaning routines. Cytotoxicity was evaluated using mouse fibroblast cultures, and cell adhesion was evaluated with osteoblast-like SaOS-2 cells. Results: The "as-produced" sample showed a pronounced surface contamination by lubricating oils. For partially and totally cleaned samples, an increasing amount of titanium and a decreasing carbon/titanium ratio was observed as cleaning became more complete. Discussion: Differences in surface chemistry such as those normally found on titanium implant surfaces (see part 1 of this series) can lead to those same effects which, in in vitro experiments, are normally accounted for in terms of surface topography alone. Conclusion: Effects related to surface chemistry can operate over and above surface topography, making it impossible, without proper characterization, to make definite statements about the role of topography alone.

Purpose: The aim of this study was to compare a bovine bone substitute (Bio-Oss) to autogenous bone with respect to its value as a material for sinus augmentation. Materials and Methods: In 10 beagle dogs 12 months of age, the 3 maxillary premolars were extracted on both sides. Six weeks later, 2 cavities of predefined size were produced in the region of the nasal cavity. The antral window was 25 mm long and had a vertical extension of 7 mm. Two Frialit-2 implants (3×8 mm) were placed in each bone defect (n = 20). Every implant was primarily stable because of fixation in native bone. In each maxilla, 1 bone defect was filled with autogenous bone harvested from the mandible and 1 was filled with Bio- Oss (material selected at random). The animals were sacrificed at 90 and 180 days, and histologic specimens were examined and the results subjected to statistical analysis by the WiIcoxon test for paired observations. Results: No healing problems were observed. Histologically, after 90 days the volume of the augmentation showed a reduction of 14.6 ± 4.4% within the Bio-Oss group and 3.8 ± 2.5% in the group with autogenous bone. Bone-implant contact of 52.16 ± 13.15% in the Bio-Oss group and 60.21 ± 11.46% in the autogenous bone group was observed. At 180 days, the Bio-Oss group showed bony ingrowth of the substitute, whereas in the autogenous group a differentiation from original bone could no longer be made. The volume reduction was 16.5 ± 8.67% in the Bio-Oss group and 39.8 ± 16.14% in the autogenous group. Bone-implant contact of 63.43 ± 19.56% in the Bio-Oss group and 42.22 ± 12.80% in the autogenous bone group was measured. Discussion and Conclusion: The results indicated that because of the nonresorptive properties of the bone substitute Bio-Oss, regeneration of the defects is achievable. It was demonstrated that the bone substitute seemed to behave as a permanent implant. The volume of the area augmented by autogenous bone decreased over the observation period.

Purpose: Questions exist as to the potential advantages of bicortical stabilization of implants in the mandible through engagement of the lingual cortical plate. The purpose of this investigation was to determine photoelastically the effect of lingual cortical plate engagement on implant load transfer. Materials and Methods: Composite photoelastic models of an edentulous posterior segment of a mandible were fabricated using plastics of different modulus to simulate cortical and trabecular bone. One model included a 3.75×15-mm threaded implant that engaged the simulated lingual cortical plate, while in the other model the implant was centrally located within the simulated trabecular bone. A metal superstructure was cast using an abutment cylinder. Simulated vertical occlusal loads were applied to the superstructure over the implant and at fixed buccal cantilever lengths. Stresses that developed within the model were monitored photoelastically and recorded photographically. Periimplant defects were then formed in the models and the loading and recording procedures were repeated. Results: Lingual cortical plate engagement generated the highest stresses at the lingual cortical plate and the buccal crestal cortical layer at the implant neck. Stress intensity within the buccal plate at the implant neck was lower than that in the centrally placed implant. In the presence of a periimplant defect, for all load conditions, more load was borne by the trabecular bone. Increasing cantilever lengths caused asymmetric load transfer with higher maximum stresses. Discussion: For both implant placements, a large portion of the applied load was taken by the crestal cortical bone simulant. Engagement of the lingual cortical plate reduced maximum stress in the crestal cortical bone by approximately 25%. With peri-implant defects, the simulated trabecular bone provided the main support of the applied load. Longer buccal cantilever lengths increased maximum stresses for all placement and crestal bone conditions. Conclusions: The results of this investigation do not indicate a clear load transfer advantage to apical engagement of the lingual cortical plate in this model.

Purpose: This study was undertaken to investigate the action of bisphosphonate on bone reactions after the placement of titanium screw implants into the tibiae of ovariectomized rats. Materials and Methods: Twelve-week-old female Wistar rats were divided into 4 groups of 18 animals each. The first group (Sham) was sham-operated, the second group (OVX) was ovariectomized only, the third group (Estrogen) was ovariectomized and received continuous estrogen with a 17ß-estradiol pellet, and the fourth group (YM-175) was ovariectomized and received bisphosphonate at a dose of 10 µg/kg of body weight. Titanium screw implants were placed in the proximal metaphyses of the tibiae 168 days after surgery. The animals were sacrificed 7, 14, and 56 days after implant placement. Undecalcified sections were prepared and evaluated by light microscopy. Histomorphometric measurements were obtained with a computer-based image analyzer to quantify the unit bone mass around the implant and the rate of implant-bone contact. Results: Ovariectomies significantly reduced implant-bone contact and the bone volume around the implants. However, in the YM-175 group, only slight differences in both bone contact and bone volume were noted compared with the Sham and Estrogen group. The woven structure of new bone in the YM-175 group was also replaced by mature lamellar bone, as in the other groups. Discussion and Conclusion: These results suggested that bisphosphonate preserved the implant-bone contact and bone volume around the implants.

Purpose: Current literature has revealed that surface etching of endosseous implants can improve bone-implant contact. The aim of this study was to evaluate the differences in bone-implant contact (BIC) between sandblasted/acid-etched and machined-surface implants. Materials and Methods: Thirty-two Sprague-Dawley rats were used in this study. Two implant surfaces, Ecotek (sandblasted/ acid-etched) and machined, were used with 1 implant placed in each tibia of the animals. A total of 64 implants were placed. BIC was evaluated at 5, 15, 30, and 60 days. Histomorphometry of the BIC was evaluated statistically. Results: The sandblasted/acid-etched surface demonstrated a greater BIC percentage than the machined surface. This difference was statistically significant only at 30 and 60 days after healing. Discussion and Conclusion: The sandblasted/acid-etched surface demonstrated a stronger bone response than the machined one at a later period of healing.

Purpose: Controversy over the long-term clinical effectiveness of hydroxyapatite (HA) -coated dental implants still persists, despite numerous clinical studies documenting high survival rates. The Ohio State University College of Dentistry undertook a 5-year prospective study of 429 HA-coated cylindric implants placed into 121 patients to determine the long-term clinical performance of the implants. Materials and Methods: All study subjects were patients screened and evaluated in the university's dental clinic by one of the principal investigators and one member of the surgical team. A total of 429 HA-coated implants were placed in 121 patients. The Ohio State University Human Subjects Committee approved and reviewed this study. Results: At the time of this report, 375 implants had completed 5 years of clinical follow-up. Beyond the 5-year limit of the study, 282 implants had completed 6 years and 114 implants had completed 7 years of clinical monitoring. The cumulative survival rate was 96% at 5 years and 95% at 7 years of follow-up. Mean combined mesial/distal bone loss was 1.2 mm in the mandible and 1.4 mm in the maxilla after 5 years of functional loading. Implant failures were most commonly associated with short implants or angled abutments. Discussion: Prospective clinical data are extremely valuable for clinicians evaluating the reliability of dental implant systems. In the present study, the implants achieved 100% osseointegration with minimal marginal bone loss, and 96% of the implants remained in function at 5 years. Conclusion: The HA-coated cylindric implants in this study provided a predictable means of oral rehabilitation.

Guided bone regeneration is an accepted surgical method employed in implant dentistry to increase the quantity and quality of the host bone in areas of localized alveolar defects. The lack of predictability in osseous regenerative procedures with various grafting materials suggests that improvement in the osteoinductive properties of these materials is highly desirable. Platelet-rich plasma (PRP), a modification of fibrin glue made from autologous blood, is being used to deliver growth factors in high concentration to sites requiring osseous grafting. Growth factors released from the platelets include platelet-derived growth factor, transforming growth factor ß, platelet-derived epidermal growth factor, platelet-derived angiogenesis factor, insulin-like growth factor 1, and platelet factor 4. These factors signal the local mesenchymal and epithelial cells to migrate, divide, and increase collagen and matrix synthesis. PRP has been suggested for use to increase the rate of bone deposition and quality of bone regeneration when augmenting sites prior to or in conjunction with dental implant placement. Only 6 human studies using PRP have been found in the dental implant literature and 5 were case series or reports. Thus, there is clearly a lack of scientific evidence to support the use of PRP in combination with bone grafts during augmentation procedures. This novel and potentially promising technique requires well-designed, controlled studies to provide evidence of efficacy.

Purpose: Conventional implant dentistry implies 2 surgical stages. In this context, pain is often present in the second stage, despite the fact that it is comparatively less aggressive for the patient. The present pilot study proposes application of Erbium:YAG (Er:YAG) laser for second-stage implant surgery. Materials and Methods: Twenty patients were studied with a total of 50 implants in which osseointegration was complete. The subjects were divided into 2 groups: a control group (10 patients with 25 implants), subjected to conventional second-stage surgery; and a group of 10 subjects (also with 25 implants) treated with the Er:YAG laser at second-stage implant surgery. Results: The use of Er:YAG laser obviated the need for local anesthesia and minimized postoperative pain and time needed before starting the second stage. With regard to surgical duration, quality of hemostasis, and success in implant treatment, no differences were reported. Discussion: In the second stage of implant surgery, different types of laser have been used, taking advantage of their bacteridal effect; disadvantages arise from inducing damage to the implant surface and adverse thermal effects. Conclusion: The advantages afforded by laser treatment include technical simplicity, the possibility of obviating local anesthesia, absence of postoperative pain and edema, and complete tissue healing by day 5, thus facilitating rapid prosthetic rehabilitation. The technique described can be used in all cases except situations where esthetic considerations prevail in anterior areas, or in the event of a lack of keratinized gingiva surrounding the implant.

Purpose: Dental implants are accepted as a successful alternative to conventional fixed and removable prostheses for the treatment of partial or complete edentulism. However, there have been few studies of the success of implants from the patients' perspective. The purpose of this study was to assess patient overall satisfaction with the outcome of treatment with maxillary anterior implants. Materials and Methods: A self-administered mailed questionnaire, which was developed for this project, and a data abstraction form, which was designed based on information available from the corresponding dental records of 123 eligible subjects, were utilized to survey implant patients. Results: Seventy-eight of 123 eligible subjects responded to the mailed, self-administered, structured questionnaire. Twelve of the 24 questionnaire variables demonstrated statistically significant bivariate associations with the dependent variable "overall patient satisfaction." Five variables-implant position, definitive restoration shape, appearance, effect on speech, and chewing capacity-were strongly associated with overall satisfaction. No demographic or treatment-related, dental record-abstracted variable, of the 25 that were examined, was statistically significant. Discussion: The practitioner who provides implant restorations should be aware of the multidimensional aspects of patient satisfaction with implant treatment. This study suggests that patient satisfaction with key elements influences the overall acceptance of maxillary anterior implant prostheses, which are esthetically critical. Communication between dentist and patient is important to achieve optimal results that will be satisfactory to both. Discussion of treatment limitations may also help patients to develop realistic expectations of the final result. Conclusions: In this limited investigation, patient satisfaction with implant position, restoration shape, overall appearance, effect on speech, and chewing capacity were critical for patient overall acceptance of the dental implant treatment.

Purpose: This study tests the possibility of using synchrotron radiation (SR) x-ray micro-imaging as a new method to evaluate osseointegration. Materials and Methods: A simple imaging setup with primarily unmonochromatic SR was used to study the interface of a dental implant in contact with bone. The samples were prepared by sectioning the undecalcified specimen of a titanium screw implanted in the tibia of a New Zealand white rabbit. Radiographs of the interface between surrounding tissues and dental titanium implant were imaged using the SR imaging system at PLS (Pohang Light Source) 5C1 beamline, a micro-computed tomography (µCT) system (SkyScan-1072), and a conventional dental x-ray system (Siemens Heliodent MD). Results: The image quality of the osseointegrated titanium implant was compared among the 3 imaging systems. The SR imaging technique showed greater details than other radiographic modalities for evaluation of the healing stage of bone-implant contact. Discussion: The evaluation was especially focused on the image quality of the osseous contact at the bone-to-implant interfaces. Conclusions: This SR imaging technique provides finer details and can be expected to make an impact in the clinical study of osseointegration.

Purpose: To evaluate the quality-of-life aspect of treatment outcome following functional jaw reconstruction and dental implants in the maxilla or mandible. Materials and Methods: This cross-sectional study used a questionnaire interview of 28 rehabilitated patients who received autogenous bone grafts from the ilium and endosseous implants (14 maxillary and 14 mandibular cases; 134 implants) for functional jaw reconstruction between 1988 and 1999. A questionnaire was developed to assess the quality-of-life outcome for those patients who had finished their rehabilitation at least 6 months prior to the interview. Responses to the questions were recorded by means of visual analog scales. Results: In general, patients gave positive comments on the restoration of their orofacial appearance and function (mastication and speech). The majority (85.7%) found no problem in various daily social activities, including dining in public. Discussion: The overall level of satisfaction with the treatment outcome and the degree of recommendation of the treatment to others were both favorable (mean scores 8.6 and 8.7 out of 10, respectively). Conclusion: Oral rehabilitation using functional jaw reconstruction can reach a satisfactory level of esthetics, function, and psychosocial well being of patients, thus improving their quality of life.

Purpose: The aim of the article was to introduce a new subantroscopic laterobasal sinus augmentation (SALSA) technique as a minimally invasive approach to maxillary peri-implant surgery. Materials and Methods: The SALSA technique consists of the following steps: (1) microsurgical opening of the subantral space (SAS) with detachment of the sinus membrane (SM) under supported videoendoscopy; (2) enlargement of the SAS by laterobasal tunnelling; (3) subantroscopic examination of the SAS with (4) optional reinforcement or repair of the SM; (5) implant site preparation with subantroscopic identification of the cavities; and (6) precise stepwise placement of graft material under endoscopic control. Results: Since 1996, 118 sinus augmentations have been performed on 83 patients using particulate alloplastic augmentation material (tricalcium phosphate) with various amounts of autogenous bone and blood. Mean augmentation height was 8.6 mm (range, 1 to 15 mm). Twentyeight perforations of sinus mucosa were observed without further complication (1 case of sinusitis was treated and re-augmented endoscopically). Of 211 titanium screw-type implants placed, 11 failures were observed. Discussion: SALSA is a predictable surgical technique. With this minimally invasive method, adequate bone height can be achieved. Conclusion: SALSA may offer advantages related to lower morbidity, conservation of bone volume and blood supply, optimized view of the surgical field, and high acceptance by patients.