The International Journal of Oral & Maxillofacial Implants, 06/2002

Purpose: Initial adhesion of cells to implant surfaces and subsequent behavior of the cells are important determinants for biocompatibility of the implants. It was previously reported that both adhesion of MC3T3-E1 osteoblast-like cells to titanium (Ti) plates and their differentiation into more mature cells on the plates were stimulated by treatment of the plates with glow discharge plasma (GDP). However, the mechanisms of these processes have not yet been identified. In this study, the adhesion and differentiation mechanism of osteoblast-like cells to Ti with and without GDP were investigated. Materials and Methods: The adhesion and differentiation mechanism of MC3T3-E1 osteoblast-like cells to Ti, with and without GDP, were investigated by cultivation in serum-free medium and use of a competitive inhibition test to examine the influence of extracellular matrix proteins contained in the serum and to identify cell binding proteins. In addition, the amount of fibronectin adsorption on each Ti plate was investigated by enzyme-linked immunosorbent assay and fluorescein isothiocyanate labeling. Furthermore, the stress fiber formation and morphology of cells on each plate were evaluated microscopically. Results: Adherent cells on Ti plates, with and without GDP, were significantly reduced in serum-free conditions and the presence of RGDS (Arg-Gly-Asp-Ser) peptides. Fibronectin adsorption on titanium plates was increased by GDP. Furthermore, stress fiber formation of cells was extremely progressive on the Ti plates treated with GDP and was not observed on the cells inhibited by RGDS peptide. Discussion: These results suggest that RGDS containing serum proteins have a major role in regulating specific adhesion of cells to Ti, and GDP promoted cell adhesion and differentiation on Ti by increasing the adsorption of proteins. Conclusion: According to this study, the adhesion and differentiation mechanism of osteoblast-like cells to Ti, with and without GDP, can be obtained.

Purpose: The aim of the present study was to evaluate whether hormone replacement therapy (HRT) and calcitonin (CT) administration could influence bone healing around implants placed in ovariectomized (OVX) rats. Materials and Methods: One screw-type titanium implant was placed bilaterally in OVX rats. The animals were assigned to one of the following groups: group 1 (n = 15), sham surgeries; group 2 (n = 15), OVX rats; group 3 (n = 14), OVX rats administered CT 4 days/week (16 IU/kg); group 4 (n = 14), OVX rats administered 17 estradiol daily (20 µg/kg). After 60 days, the animals were sacrificed and undecalcified sections obtained. Bone-to-implant contact (BIC) and bone area (BA) around the implants were determined separately for the cortical (zone A) and cancellous (zone B) bone areas. Results: In zone A, intergroup analysis did not reveal a significant difference regarding BIC. In contrast, the HRT group (group 4) presented greater BA than groups 2 and 3 (P .05). Data from zone B revealed that HRT eliminated the negative effect of the ovariectomy on BIC and BA (P .05), while CT had no effect (P > .05). Discussion: It was the first study to evaluate and demonstrate the impact of HRT and CT on bone around titanium implants in an estrogen-deficient model. Conclusion: Within the limits of the present study, it may be concluded that HRT may prevent the influence that estrogen deficiency exerts on bone healing around titanium implants.

Purpose: The microbial colonization of new ceramic materials developed for abutment manufacturing was assessed. Materials and Methods: The materials used in these experiments were disks of "asfired" and "rectified" ceramic material made of tetragonal zirconia polycrystals stabilized with yttrium (Y-TZP) and commercially pure grade 2 titanium (Ti) with corresponding eluates. They were tested in vitro with the following bacteria: Streptococcus mutans, S sanguis, Actinomyces viscosus, A naeslundii, and Porphyromonas gingivalis. Proliferation was evaluated on plates by inhibitory halos around pits, previously inoculated with eluates obtained from the materials. Bacterial adhesion on materials was quantified by spectrophotometric evaluation of the slime production by the same bacteria. Moreover, early bacterial adhesion was evaluated in human volunteers and observed with SEM. Results: No inhibition of bacterial proliferation using eluates was observed. In vitro as-fired and rectified Y-TZP showed significantly more adherent S mutans than did Ti disks, while S sanguis seemed to adhere easily to Ti specimens. No differences were noted for Actinomyces spp and P gingivalis. In vivo Y-TZP accumulated fewer bacteria than Ti in terms of the total number of bacteria and presence of potential putative pathogens such as rods. No differences were observed between rectified and as-fired Y-TZP. Discussion: Overall, Y-TZP accumulates fewer bacteria than Ti. Conclusion: Y-TZP may be considered as a promising material for abutment manufacturing.

Purpose: The aim of this longitudinal study was to gain 5-year clinical documentation of the 1-stage surgical technique in connection with ITI solid-screw implants used in the edentulous mandible. Materials and Methods: One hundred patients with totally edentulous mandibles were treated with barretained overdentures supported by a total of 340 consecutively placed ITI solid-screw implants. The patients were followed at annual intervals for at least 5 years to evaluate implant success, longitudinal reactions of the peri-implant hard and soft tissues, and incidences of biologic and mechanical complications. Results: During the trial period, a total of 4 implants failed, all prior to loading, and 51 implants were lost to follow-up, resulting in a cumulative survival rate of 98.8% after 5 years of functional service. The success analysis included additional strictly defined events (either "first occurrence of marginal bone loss >= 4 mm" or "first occurrence of pocket depth >= 4 mm" and "first occurrence of crevicular fluid flow rate >= 2.5 mm") and resulted in a cumulative 5-year success rate of 95.7%. The median marginal bone loss experienced between implant placement and prosthetic treatment was 0.5 mm, followed by an annual bone level change of 0.1 mm for the functional period of 5 years. The increasing incidence of remarkable plaque deposits from 19% to 50% represented the difficulties of the patients in maintaining a high level of oral hygiene, particularly for the lingual surfaces. Sulcus Bleeding Index, probing depth, attachment level, and crevicular fluid flow rate were used to describe the health of the peri-implant soft tissues and remained almost within acceptable standards. Discussion: Survival and success rates of implants, amount of marginal bone loss, and periodontal indices of peri-implant soft tissues were consistent with those reported in the literature regarding implants with the submerged healing concept. Conclusion: With a cumulative survival rate of 98.8%, a cumulative success rate of 95.7%, and a median marginal bone loss of 0.5 mm during the healing period, followed by an annual rate of 0.1 mm after loading, non-submerged ITI solid-screw implants confirm the good clinical outcome of implant-supported treatment concepts for the rehabilitation of totally edentulous patients in a medium-term perspective.

Purpose: Although no currently available technique for the measurement of osseointegration is entirely satisfactory, 3 clinical variables can be reasonably associated with the process: probing depth, micromobility, and crestal bone height. Micromobility can be quantified to some extent with the use of the Periotest, a commercially available instrument. In this investigation, the influence of surface characteristics and geometry upon Periotest value (PTV) and probing depth measurements was studied. Materials and Methods: In a multicenter trial, 120 healthy edentulous patients received 5 or 6 implants in the anterior mandible and were followed for 3 years. A total of 634 implants were placed. Every patient received at least 1 implant of each of 3 types: threaded titanium plasma-sprayed (TPS), threaded hydroxyapatite-coated (HA), and cylindric HA-coated. A randomization schedule assured that approximately equal numbers of each type of implant were placed and that they were uniformly distributed over the arch. Results: Of the 4 tested combinations of dependent and independent variables, the only statistically significant (P .05) effect was that of coating on PTV. At 1 year after prosthetic restoration, the mean PTV for HA-coated threaded implants was -5.36 ± 1.24, compared with -4.86 ± 1.70 for TPS implants. This difference steadily declined in magnitude and significance, until, after 3 years, the groups were indistinguishable. Discussion: This study agrees with the previous observations that HA coating tends to accelerate the initial rate of osseointegration. The absence of a difference between threaded and cylindric implants confirms that the PTV responds to micromobility near the surface, on a scale much smaller than such gross geometric features. Conclusion: On the basis of these results, one may conclude that HA-coated implants exhibit a more rapid decrease in micromobility than do TPS implants of identical geometry.

Purpose: The present study evaluated the effect of smoking on achieving initial osseointegration when surface-modified dental implants were used. Materials and Methods: During an 18-month period in a private practice setting, 1,183 implants were placed in 461 patients. The group of smokers consisted of patients who smoked a half pack or more of cigarettes per day. Results: The overall success rate for smokers and non-smokers in achieving osseointegration was 98.1%. Ninety-seven percent of the implants placed in smokers osseointegrated successfully, and 98.4% of implants placed in non-smokers osseointegrated successfully (P .05). Discussion: The surface of an implant may be a critical determinant for achieving osseointegration in patients who smoke. Conclusion: It appears from this short-term retrospective study that smoking does not play a significant role in achieving the osseointegration of surface-modified dental implants.

Purpose: The purpose of this prospective multicenter study was to evaluate the efficacy of 3i threaded implants for the treatment of edentulous patients in a 1- to 5-year period. This article reports the total data and global results of 3 threaded designs of 3i implants: self-tapping, ICE, and Osseotite. Materials and Methods: A total of 1,583 implants (619 ICE, 545 Osseotite, and 419 self-tapping) were placed between 1995 and 1999 in 528 patients at 13 European clinical centers. The average age of the patients was 53.6 years. Clinical and radiographic evaluations were performed annually for up to 5 years. Results: Of the total implants, 707 were placed in the maxilla and 876 in the mandible. A total of 1,162 implants were placed in posterior segments. Forty-eight implants were lost to follow-up and 55 were failures. The most frequent prosthetic indication was the short-span fixed prosthesis (440 cases), followed by 172 single-tooth replacements, 56 long-span prostheses, and 4 overdentures. Radiographic evaluation after 6, 12, and 24 months of implant loading showed, respectively, mean crestal bone loss of 0.04 ± 1.3 mm, 0.12 ± 1.6 mm, and 0.2 ± 1.7 mm. A cumulative survival rate of 96.5% was observed 5 years after implant placement, with 97.2% survival in the maxilla and 95.8% in the mandible. The survival rate was similar in anterior (96.7%) and posterior (96.5%) segments. Discussion: A total of 55 failures were reported in this study with 47 early failures and 8 late failures. The rate of late failures is of utmost importance for the restorative dentist. Conclusion: This clinical study gives evidence of very high success rates using 3 threaded designs of 3i implants.

Although high success rates for root-form endosseous implants have been reported, failures occasionally occur, and these implants must be removed. At least 10% of the failures have been suggested to be the result of peri-implantitis. There is some evidence that periodontal pathogens, mainly those belonging to the group of Gram-negative anaerobic rods, play a role in the etiology of peri-implantitis. This article provides an overview of the literature associated with common peri-implant microbiology and an assessment as to whether bacteria associated with periodontitis exert a possible risk for periimplant tissue breakdown. The peri-implant area is colonized by a large variety of oral microbial complexes. The microflora of the oral cavity prior to implant placement determines the composition of the microflora in the peri-implant area. Implants involved in peri-implantitis are colonized with large amounts of Gram-negative anaerobic bacteria, including Fusobacteria, spirochetes, Bacteroides forsythus, and "black-pigmented bacteria" such as Prevotella intermedia, Prevotella nigrescens, and Porphyromonas gingivalis. Also, Actinobacillus actinomycetemcomitans can be isolated from these lesions. Thus, the microflora of peri-implantitis lesions resembles that of adult or refractory periodontitis. However, the presence of periodontal pathogens does not always lead to a destructive process. Therefore, the etiologic role of specific microorganisms in implant failure related to infection is still not resolved. Controversy remains as to whether organisms recovered from the original microflora cause the failure (and if so to what extent) or merely result from the infection. Nevertheless, there is accumulating evidence that bacteria cause the disease, while the individual's genetic makeup and environmental influences determine the severity of the disease.

osseointegration of conventional implants while a patient was provided with immediate esthetics and function. The purpose of this study was to evaluate the removal torque values of immediately loaded transitional implants in human subjects. Materials and Methods: Thirty-one 1.8-mm-diameter transitional implants were placed in 4 patients to support provisional restorations and were subjected to immediate loading. Removal torque values were recorded using a modified ITI torque driver, which was calibrated on an Instron test machine. Torque values were subjected to analysis of variance and post hoc comparisons of means (P .05). Results: Twenty-six implants were removed intact with torque values between 10.5 and 22.9 Ncm, while 5 fractured at the bone crest at values between 27.1 and 35.4 Ncm. Mean torque values increased with time in function. These values were significantly lower in the maxilla (16.1 ± 4.8 Ncm) than in the mandible (24.0 ± 7.3 Ncm). Discussion: Results suggest that these transitional implants may be safely removed from the maxilla after 7 to 15 months, but there is a risk of implant fracture during removal from the mandible after 10 months. Conclusion: Removal torque levels for these implants indicate varying degrees of integration even though they were subjected to immediate loading.

Purpose: The purpose of this study was to determine the prevalence, size, location, and morphology of maxillary sinus septa in dentate, partially dentate, and edentulous maxillae. Materials and Methods: Data from 312 sinuses were analyzed from reformatted computerized tomograms utilizing SlM/Plant software. The sample consisted of 156 patients (106 women and 50 men, with ages ranging between 24 and 86 years and a mean age of 55.4 years) who were being treatment-planned to receive implantsupported restorations. Results: A total of 75 septa were found in 312 maxillary sinuses (24%), which corresponded to 32.7% of the patients (51 of 156). Completely edentulous patients presented with 33.3% of the total septa, while 66.7% of the septa were identified in partially edentulous patients. Analysis of the anatomic location of the septa within the sinus revealed that 18 (24.0%) septa were located in the anterior region, 31 (41.0%) were in the middle, and 26 (35.0%) were in the posterior region. Measurements of height of the septa varied among different areas. The lateral area ranged from 0 to 15.7 mm (with a mean of 3.54 ± 3.35 mm), the middle area ranged from 0 to 17.3 mm (with a mean of 5.89 ± 3.14 mm), and the medial area ranged from 0 to 20.6 mm (with a mean of 7.59 ± 3.76 mm). A total of 20 septa (26.7%) were located in the immediate apical region of teeth. The remaining 55 septa (73.3%) were related to edentulous areas. Discussion: Septa may arise in any of the 3 regions of the maxillary sinus irrespective of the degree of dentulism or edentulism present. Conclusion: To avoid unnecessary complications during sinus augmentation procedures, adequate and timely identification of the anatomic structures inherent to the maxillary sinus are required.

The Brånemark Zygomaticus implant was used in conjunction with premaxillary standard implants for the reconstruction of resorbed edentulous maxillae. A total of 44 zygomatic implants and 80 premaxillary implants were placed in 22 patients. All implants were stabilized at phase II surgery using a rigid bar. After soft tissues had healed, implant-supported fixed prostheses were fabricated. This article presents a preliminary report on 22 patients followed for 34 months, with a 100% success rate for the zygomatic implants and a 91.25% success rate for the premaxillary implants.

Development of gingival contours found in healthy natural dentitions enhances the esthetic results achieved with implant-supported fixed prostheses. However, this endeavor is frequently difficult to achieve, especially in the completely edentulous patient. Edentulous patients with optimal hard and soft tissue can be treated with a specially designed removable prosthesis that will develop gingival contours prior to implant placement. By means of a transitional complete removable prosthesis with ovate pontics and no labial flange, a natural-looking soft tissue profile can be developed prior to dental implant placement. A minimally invasive tissue punch surgical technique is used to place the implants, which are immediately restored with a 1-piece, cross-arch, provisional fixed prosthesis. This article presents the prosthodontic and surgical protocols utilized to improve the appearance of the definitive implant rehabilitation.

Restoration of the atrophied posterior mandibular alveolus has been a surgical challenge in the past. Many treatment options have been published, each with unique shortcomings. This study will review and compare these techniques to a new type of implant, the transverse alveolar maxillary/mandibular implant (TAMMI). Using modified Nobel Biocare Brånemark System zygomatic implants that were shortened to 11.5, 13, 15, 18, 20, 22.5, or 25 mm, the authors reconstructed atrophied posterior mandibles. These TAMMIs were placed at a 45-degree angle, engaging both the crest of the ridge and the buccal cortex. Using TAMMIs, atrophied posterior mandibular alveoli as small as 9 mm have been successfully restored without complication to the inferior alveolar nerve.