Pages 383, Language: EnglishLaney, William R.Pages 391-398, Language: EnglishClelland, N. L. / Ismail, Y. H. / Zaki, H. S. / Pipko, D.The three-dimensional finite element stress analysis method was used to determine the pattern and concentration of stresses within the Screw-Vent endosseous implant and its supporting tissues. For this commercially pure titanium implant, maximum stresses were located within the implant collar immediately below the bony crest. These stresses were at least 18 times less than the endurance limit of commercially pure titanium (259.90 MPa). Maximum stresses (19.57 MPa) in the bone were lingual to the superior portion of the collar. Previous longitudinal radiographic studies of a similar implant have revealed bone loss mesial and distal to the implant. For the Screw-Vent, mesial and distal stresses (maximum 0.38 MPa) were much lower than those buccal and lingual to the implant. The clinical significance of the stress transfer to the bone buccal and lingual to the implant has yet to be determined.
Keywords: bone, endosseous implant, stress transfer, three-dimensional finite element method
Pages 399-404, Language: EnglishGottlander, Magnus / Albrektsson, TomasThreaded hydroxylapatite-coated implants of commercially pure (CP) titanium were inserted in the rabbit tibial metaphysis. Uncoated CP titanium screw implants inserted in the contralateral leg served as controls. After 6 weeks and 1 year postinsertion, the semiloaded implants were histomorphometrically analyzed. While not significant, there was more direct bony contact with the hydroxylapatite-coated implants after 6 weeks of follow-up. One year after insertion, there was significantly more direct bone-to-implant contact with the uncoated CP titanium controls.
Keywords: histomorphometry, hydroxylapatite, threaded implants, titanium
Pages 405-412, Language: EnglishBuser, Daniel / Weber, Hans Peter / Brägger, Urs / Balsiger, ChristianThis study examined the tissue integration of one-stage, nonsubmerged ITI implants over a period of 3 years. Fifty-four implants were placed in 38 partially edentulous patients. Following healing (at least 3 months), all 54 implants were free of peri-implant infections and revealed no detectable mobility. Radiographs showed no signs of peri-implant radiolucencies, and the implants were in favorable positions for prosthetic restoration. Following incorporation of fixed partial dentures, patients were enrolled in a hygiene recall program with 3-month intervals and were examined once a year. Based on predefined criteria, each implant was classified as successful or failing. After the 3-year observation period, 51 of 53 implants (96.2%) were considered successfully integrated. (One patient with one implant dropped out of the study.) Two implants exhibited recurrent peri-implant infections and were classified as late failures. These results indicate that one-stage ITI implants can achieve successful tissue integration on a predictable basis and that it can be maintained over a period of at least 3 years.
Keywords: criteria of success, ITI implants, long-term study, one-stage implants, tissue integration
Pages 413-417, Language: EnglishJemt, Torsten / Carlsson, Lennart / Boss, Anders / Jörnéus, LarsLoad was measured in vivo on a single terminal abutment cylinder by means of a strain gauge technique. The clinical measurements were made on one female patient (age 62) provided with six implants in the edentulous maxilla. A fixed prosthesis was tested initially, followed by an overdenture supported by a bar connected to the implants. The results indicated that a significant force could be introduced when connecting the framework. Furthermore, measurements showed that compression/tension forces were lower in the overdenture situation. However, the preliminary data also indicated relatively higher bending moments on the implant when the overdenture was loaded.
Keywords: bending moment, compression/tension force, load, overdenture
Pages 418-426, Language: EnglishBurchard, W. Brent / Cobb, Charles M. / Drisko, Connie L. / Killoy, William J.This study evaluated, in vitro, the attachment of gingival fibroblasts to dental implants of differing surface character treated with 0.12% chlorhexidine, 1.64% stannous fluoride, or sterile saline. Specimens were divided into three groups, each composed of 18 dental implants. Each group featured a different implant surface texture, ie, smooth titanium, hydroxylapatite plasma-spray, or titanium plasma-spray. Following adsorption of salivary pellicle, six implants from each group were treated with chlorhexidine, stannous fluoride, or sterile saline. They were then cultured with fibroblasts for 24 hours and photographed by scanning electron microscopy. Cell counts were then performed. Analysis of results showed a significantly greater number of fibroblasts attached to specimens treated with saline or chlorhexidine than to those treated with stannous fluoride. Furthermore, fibroblasts were more likely to attach to rough-surfaced than to smooth-surfaced specimens.
Keywords: dental implants, chlorhexidine, fibroblasts, implant maintenance, stannous fluoride
Pages 427-436, Language: EnglishTolman, Dan E. / Keller, Eugene E.Seven patients who had previously received mandibular endosseous implants sustained mandibular fractures and were treated. Three patients had advanced bone resorption and developed stress fractures through previous endosseous implant sites. Two patients sustained fractures through implant sites via trauma. Two patients sustained fractures anatomically separated from the implants, which caused an alteration in the dental occlusion. This report describes the treatment approach for these seven patients and reviews the treatment philosophy and procedures involved. A conservative treatment approach is advised when the fracture transverses through a stable or a recently failed implant site.
Keywords: endosseous implants, mandibular fractures
Pages 437-441, Language: EnglishJohansson, Carina B. / Sennerby, Lars / Albrektsson, TomasScrew-shaped commercially pure (CP) titanium and Vitallium® implants were inserted in the rabbit tibial metaphysis. After a healing period of 3 months, it was demonstrated that a higher torque was needed to remove the CP titanium implants (average 24.9 Ncm) compared to Vitallium implants (average 11.7 Ncm). The histomorphometric part of the study revealed more bone-to-metal contact for the CP titanium implants (average 34.7%) compared to the Vitallium implants (average 21.7%). The results obtained in this study could be explained by differences in the topography or in biocompatibility of the metals, or a combination of these two factors.
Keywords: biocompatibility, commercially pure titanium, surface topography, Vitallium®
Pages 442-447, Language: EnglishUeda, Minoru / Matsuki, Masanori / Jacobsson, Magnus / Tjellström, AndersInsertion torque and removal torque of fixtures were measured using human cadaver temporal bone and human living bone. The torque level for fracturing the threads of the bone was also measured. The maximum insertion torque exerted without causing a break in bone threads was 70.0 Ncm in bicortical bone and 50.0 Ncm in unicortical bone. The relationship between insertion torque and removal torque indicated a positive correlation between both sites. However, removal torque was lower than insertion torque in all measurements. The fracture points of bone threads were 77.0 Ncm in bicortical bone and 57.7 Ncm in unicortical bone by mean. Microfractures were observed mainly in the thread bases and were directed upward in the histologic specimens examined.
Keywords: insertion torque, removal torque, osseointegrated implants, temporal bone, titanium
Pages 448-455, Language: EnglishCarr, Alan B.Production of an accurate dental cast framework that meets the implant objective of passive fit demands an understanding of potential processing errors. Working casts fabricated from impressions using two different transfer copings as provided by a leading implant manufacturer, were investigated for differences in accuracy. A five-implant mandibular model was used to produce seven casts by both the indirect and direct transfer coping techniques. Comparison was made by using a dental cast framework fitted to the master cast. Differences in distances measured between each group and the master cast were analyzed to establish differences between methods. For the model used, the direct technique produced more accurate working casts. A concern for potential impression distortion given the specific clinical situation underscores the method of choice.
Keywords: direct transfer, impression distortion, impression technique transfer method, indirect transfer, transfer coping
Pages 456-462, Language: EnglishLum, Lawrence B. / Beirne, O. Ross / Curtis, Donald A.It has been suggested that the long-term success of blade implants could be improved by placing the implants using a two-stage surgical protocol to allow the implant to develop a direct bony interface instead of a fibrous tissue interface. This study compared the implant interfaces of delayed and immediately loaded blade implants in nonhuman primates. A second objective was to compare the effects of hydroxylapatite coating on delayed and immediate loading applications. The delayed loaded uncoated titanium and hydroxylapatite-coated blade implants did osseointegrate. This study also suggests that hydroxylapatite-coated blade implants may form a direct bony interface even when they are loaded immediately after implantation, provided that they are splinted to a firm natural tooth.
Keywords: blade implants, functional loading, histologic evaluation, hydroxylapatite coating
Pages 463-469, Language: EnglishBarnes, Caren M. / Fleming, Lisa S. / Mueninghoff, Leonard A.This investigation was conducted to determine the effects of an air abrasive polishing system on various implant surfaces. Four each of the following types of implants were obtained from the manufacturer: Stryker DB (a titanium alloy implant), Denar Steri-Oss (a pure titanium implant), IMZ (pure titanium polished collar/plasma-sprayed body), and IMZ transmucosal implant extensions (highly polished pure titanium). Four samples of each type of implant material were placed in a group to be treated with an air-abrasive polishing system for 0.5, 1, 5, or 10 seconds, for a total of 16 samples. Scanning electron photomicrographs taken of each sample before and after treatment were analyzed by three examiners who were blind to the treatment conditions. They determined if the abrasion on the treated surface was greater than, equal to, or less than the pretreatment control. No perceptible difference was noted between the pretreatment and posttreatment photomicrographs regarding the surface integrity of the implant material surfaces.
Keywords: air-abrasive polishing, implant surfaces, plaque removal, stain removal, tooth surface polishing
Pages 470-474, Language: EnglishKent, Gerry / Johns, RichardForty-seven patients participated in a longitudinal study on the psychological effects of the Brånemark implant technique. They were asked to complete questionnaires measuring their psychological well-being and symptom level on two occasions. The first occasion was shortly after the initial prosthetic assessment. Although 29 patients were subsequently accepted for implant treatment, 18 were found to be unsuitable at the later surgical assessment. Both groups of patients were again given the questionnaires approximately 2 years later. The implants were associated with a clinically significant improvement on measures of symptoms and psychological distress, but there was no change in self-esteem. By contrast, the only change in the untreated comparison group was that their level of distress had risen.
Keywords: osseointegrated implants, psychological effects, self-esteem, symptoms
Pages 475-480, Language: EnglishHulterström, Matti / Nilsson, UlfSixty-six consecutive patients treated at the Prosthodontic Clinic in Uppsala, Sweden, received implant-supported fixed prostheses of the Brånemark type. The prosthesis frameworks were made of cobalt-chromium alloys. Different techniques for attaching the gold cylinders to the frameworks were used. Mechanical attachment with self-curing polymethyl methacrylate (PMMA), partial soldering combined with PMMA attachment, and soldering only were used. No abnormal tissue reactions were seen. Radiographic examination of the fixtures was performed at the time of prosthesis placement and at the 1- and 3-year follow-ups. A few cases of minor bone loss were detected but not related to the materials used in the superstructures.
Keywords: alloys, Brånemark implants, design, framework, osseointegration, prosthodontics, soldering
Pages 481-484, Language: EnglishChristiansen, Robert L.This article concerns one of the major problems of all implants: the risk for latent potential infections. A case report involving latent infection of a mandibular implant is presented.
Keywords: debridement, hygiene, infection, osteomyelitis
