Local and systemic conditions potentially compromising osseointegration. Consensus report of Working Group 3.
Explore the source record for details and available documents.
Alveolar Ridge Augmentation↗
SEARCH · Search PubMed
Results for “Prosthesis Retention”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Periodontal aspects of osseointegrated fixtures supporting an overdenture. A 4-year retrospective study.
196 Brånemark implants in 86 consecutive patients rehabilitated by means of overdentures (6 upper jaws, 80 lower jaws) were observed longitudinally. In each jaw, only 2 implants were used to anchor the overdenture. 2 implants in the lower jaw showed some mobility at the abutment installation and were removed immediately. During the loading period (mean loading time 19.1 months ranging from 4 to 48 months), none of the implants showed any signs of non-integration. The marginal tissue reaction and plaque accumulation were monitored using conventional indices. Clinical methods and standardized radiographs were used to evaluate the bone level and density. The numbers of approximal surfaces without plaque (40%) or with gingival inflammation (55%) were almost constant throughout the study. The probing pocket depths remained within the range of 2.7 to 3.2 mm during the observation time, whereas the distance of the gingival margin from the top of the abutment clearly increased (from 1.8 to 2.9 mm). For loaded lower jaw implants connected to each other with a straight bar, a radiographic bone loss of 0.8 mm was observed during the first postsurgical year followed by a mean annual bone loss of less than 0.1 mm. For the "sleeping" fixtures, 50% less bone loss was recorded. For loaded but not interconnected implants in the upper jaw, the bone loss during the first 6 months reached 2.0 mm. The loss in marginal bone height did not clearly correlate with parameters such as the plaque index, the gingivitis index, the presence or absence of gingiva around the abutment, or the implant length. The present data, with an observation time up to 4 years, showed that the failure rate for Brånemark implants supporting overdentures in the lower jaw can be limited to 1%. However, the use of 2 unconnected fixtures in the upper jaw cannot presently be advocated since considerable bone loss was observed.
Adult↗
Probing depth at implants and teeth. An experimental study in the dog.
The aim of the present investigation was to assess the resistance offered by the gingiva at teeth and the peri-implant mucosa at osseointegrated titanium implants to mechanical probing. 5 beagle dogs were used in the experiment. The 2nd and 3rd premolars and the 1st molars of the right and left mandibular dentition were extracted. 2 titanium implants were installed in the edentulous right and left premolar- and molar-regions. Abutment connection was performed 3 months later. The remaining premolar in the left jaw (P4) was exposed to "experimental periodontitis" during a 4-month period and, thus, the 4th premolar in the right jaw (4P) was representing healthy periodontium. The inflamed soft tissues at P4 were treated using a flap procedure. Following 2 weeks of healing, the main experiment was started, i.e., day 0. During the subsequent 360 days, the teeth and abutment parts of the implants were regularly exposed to plaque control (3 x/week). Radiographs of 4P-, P4- and the implant-regions were obtained on days 0 and 360. Mobility measurements were performed on days 0 and 360. Biopsies of the experimental teeth and the implants were sampled at the end of the study. The results of the present experiment demonstrated that differences in terms of tissue composition, organization and attachment between the gingiva and the root surface on one hand and between the peri-implant mucosa and the implant surface on the other, make the conditions for probing depth measurements at teeth and implants different.(ABSTRACT TRUNCATED AT 250 WORDS)
Alveolar Process↗
Factors related to Periotest values in endosseal implants: a 9-year follow-up.
Periotest values (PTV) of successful endosseal implants of 2 one-stage implant systems. TPS and ITI, were followed from 3 months to 9 years in order to determine the factors that contribute to the values. 128 TPS screw implants were inserted in the lower jaw of 34 subjects, (mean age 55 years), for retaining overdentures. 108 ITI implants were inserted in the upper and lower jaws in 50 subjects (mean age 42 years), for retaining overdentures, crowns and bridges. PTVs were first measured after the osseointegration period and thereafter annually. First of all there was a difference between the 2 implant systems. Mean PTVs of TPS bicortical screws were significantly lower (P < 0.05) than those of ITI implants (screws, hollow-screws, hollow-cylinders). Factors which significantly contributed to PTVs of ITI implants were jaw (upper/lower), implant length and region of the jaw in which the implant was inserted. PTVs of ITI implants in the lower jaw were lower than in the upper jaw (P < 0.05). The length of implant had no effect on PTVs in the lower jaw, but in the upper jaw, PTVs of ITI 8-10-mm implants were lower than 12-mm implants (P < 0.05). PTVs of implants inserted in the anterior region of the upper jaw were higher than those in the posterior region (P < 0.05). In conclusion, bone quality and implant length had a statistically significant effect on implant mobility in long-term follow-up. PTVs of various implant systems, however, differ, a fact that must be taken into account in evaluating the success of implants.
Adult↗
Clinical parameters for the evaluation of dental implants.
Explore the source record for details and available documents.
Dental Implants↗
Astra Tech and Brånemark System implants: a prospective 5-year comparative study. Results after one year.
BACKGROUND: Endosseous dental implants are used frequently, and many implant systems are available. The scientific documentation of the implant system presents a great variation, and it is often difficult to compare studies of different systems. PURPOSE: The aim of this study was to compare two Swedish implant systems (Astra Tech and Brånemark System implants), in a prospective randomized study. MATERIALS AND METHODS: Sixty-six patients were equally distributed between the two implant systems; 184 Astra Tech and 187 Brånemark System implants were used. The patients have been followed annually with clinical and radiographic examinations. The results after 1 year are reported. RESULTS: The abutment procedure was found to be easier and less time-consuming with Astra Tech than with Brånemark implants. The operation times in minutes (mean +/- SEM) were for the respective implant 35 +/- 4.0 and 51 +/- 4.8 in the maxilla and 32 +/- 3.8 and 43 +/- 2.4 in the mandible. The differences in both cases were significant: p < .02 and p < .05, respectively. The failure rate for Astra Tech implants was 0.5% and for Brånemark implants 4.3%. The difference was significant (p < .05); however, taking into account that five of the eight implant losses in the Brånemark implant group occurred in one patient, an intraindividual correlation cannot be excluded. Therefore, this result should be interpreted with caution. The marginal bone level changes were examined already from the fixture installation. The major bone loss was found between fixture installation and baseline. This bone loss was several times greater than the bone loss between the baseline and the 1-year follow-up. The total bone loss during the observation period did not differ significantly between the systems, but they had different resorption patterns. The bone loss in the upper jaw between baseline and 1-year follow-up was 0.22 +/- 0.14 and 0.03 +/- 0.09 mm for the Astra Tech and Brånemark implants, respectively. In the lower jaw, the loss was -0.31 for both systems. The frequency of plaque accumulation and bleeding on probing did not differ between the implant systems. CONCLUSIONS: Abutment connection with Astra Tech implants was simpler than the corresponding surgery with Brånemark System implants and the survival rate of Astra Tech implants was higher than that of Brånemark system implants.
Adult↗
Five-year evaluation of implants placed at extraction and with dehiscences and fenestration defects augmented with ePTFE membranes: results from a prospective multicenter study.
BACKGROUND: Barrier membranes have been used to promote bone ingrowth on implants with dehiscences and fenestrations. Membranes also have been used to protect defects adjacent to implants placed at the time of extraction. The concept of guided bone regeneration relates to preferentially allowing cells from bone to migrate into various defects while excluding fibrous tissue and epithelium. The purpose of these procedures is to enhance bone-to-implant contact at the treated sites and to prevent mucosal complications. PURPOSE: The purpose of this article is to report clinical outcomes for implants placed at the time of extraction and augmented with expanded polytetrafluoroethylene (ePTFE) and followed for 5 years. The outcomes for implants with dehiscences and fenestrations augmented with ePTFE barriers and followed up to 5 years also are reported. METHODS AND MATERIALS: Four treatment centers participated in this study (Tucson, Gothenburg, Spokane, and Leuven). In the extraction group, teeth were removed for varying reasons, and Brånemark implants were placed and stabilized within the host bone. Defects present at the coronal implant aspect were covered with ePTFE barrier membranes. Flaps were rotated to cover the membrane-treated sites. If exposure of the material occurred prior to second-stage surgery, the membranes were removed. Barriers remaining unexposed were removed at second-stage surgery. The implants were followed up to 5 years. In the fenestration and dehiscence group, implants with exposed threads were augmented with ePTFE barrier membranes. The barriers were removed at appropriate intervals, and the patients were followed up to 5 years. Radiographic measurements were made from nonstandardized periapical radiographs at abutment connection and 1, 3, and 5-year follow-up visits. RESULTS: Forty patients participated in the extraction group. They received a total of 49 implants. Three implants failed prior to loading. The 5-year cumulative survival rates for implants placed at the time of extraction were 93.9% and 93.8%, respectively, for maxillary and mandibular implants. The average maxillary mesial and distal marginal bone loss (1-5 yr) was 0.3 mm (standard deviation [SD] = 1.5) and 0.3 mm (SD = 1.0). In mandibles, the average mesial and distal bone loss (1-5 yr) was -0.2 mm (SD = 0.5) and -0.05 mm (SD = 0.6), respectively. The dehiscence and fenestration group included 44 patients. Twenty-six were followed for up to 5 years. Eight patients experienced total implant failure. For dehiscences and fenestrations, the cumulative survival rates were 76.8% and 83.8% for maxillary and mandibular implants, respectively. The average maxillary mesial and distal bone loss (1-5 yr) was 0.4 mm (SD = 0.8) and 0.2 mm (SD = 0.9), respectively. In mandibles, the average mesial and distal marginal bone loss was 0.3 mm (SD = 0.9) and 0.3 mm (SD = 0.8), respectively. CONCLUSIONS: Implants placed at the time of extraction and augmented with ePTFE barrier membranes have favorable long-term predictability. On the other hand, long-term evaluation of implant dehiscences and fenestrations augmented with barrier membranes indicates that they have less favorable 5-year survival rates. Membrane augmentation of these may be questioned.
Adolescent↗
Implant stability measurements using resonance frequency analysis in the grafted maxilla: a cross-sectional pilot study.
BACKGROUND: High failure rates have been presented for implants placed in grafted bone. The bone graft-implant interface constitutes a most complex healing situation, where the time scale for osseointegration and development of implant stability currently is not known. PURPOSE: The aim of the study was to measure the stability of implants placed in grafted bone after various follow-up periods. METHODS: Implant stability measurements by means of resonance frequency analysis were performed in 10 patients previously treated with a Le Fort I osteotomy and interpositional bone grafts. The implants were placed 3 to 4 months after the grafting procedure. Sixty-seven Brånemark implants were subjected to resonance frequency analysis measurements at fixture placement and up to 5.5 years after implant surgery. Periapical radiographs were used for assessment of marginal bone levels. RESULTS: The radiographic examinations showed marginal bone loss with time during the 5.5-year follow-up. The resonance frequencies varied from 5860 to 8440 Hz. When accounting for abutment length and marginal bone level, there was a tendency of increasing resonance frequency with time. Two implants with low resonance frequencies failed during the prosthetic phase. CONCLUSION: The results indicate an increased implant stability with time, which may reflect bone formation, remodeling, and maturation at the implant interface.
Aged↗
On cutting torque measurements during implant placement: a 3-year clinical prospective study.
BACKGROUND: Evaluation of jaw bone quality at implant placement is mainly based on preoperative radiographic assessments and subjective hand registrations during implant site preparation. An objective technique with cutting torque measurements has been introduced, presenting an objective bone quality or bone hardness value of individual implant sites. PURPOSE: The purpose of this study was to evaluate cutting torque measurements during implant placement and to compare these values in different regions in mandibles and maxillae. The objective was to identify implants at risk for failing at implant placement. MATERIAL AND METHODS: Cutting torque measurements were performed during placement of Mk II self-tapping implants (Brånemark System) in 105 patients, comprising 72 edentulous (40 maxillae) and 34 partially edentulous (22 maxillae) jaws. A total of 523 implants were inserted, of which 420 were of the Mk II design and of which 412 were subjected to cutting torque measurements. Statistical analyses were performed by comparing cutting torque values of maxillae and mandibles and of different jaw regions. Cutting torque values were also correlated with radiographically and clinically assessed bone quality scores. Patients were followed clinically for a minimum of 3 years. RESULTS: A statistically significant difference in cutting torque values of maxillae and mandibles was seen, although not when comparing anterior and posterior regions within the same jaws or of different jaws. Significant correlations were found between values of cutting torque and bone quality. The majority of failures were seen in bone of medium to high density, whereas implants inserted in bone of poor density presented a better outcome, perhaps due to an adapted surgical protocol and an extended healing period. The overall implant survival rate at 3 years was 95%, and when analyzing different jaw categories, survival rates of 92.0% and 99.4% were seen for edentulous maxillae and mandibles, respectively. The corresponding figures for partially edentulous jaws were 95.4% and 97.6%. CONCLUSION: It was not possible to identify sites at risk for future implant losses or to determine a lower limit value of cutting torque in order to achieve successful implant integration.
Adolescent↗
Implant success versus survival.
Explore the source record for details and available documents.
Dental Implants↗
Anchorage of titanium implants with different surface characteristics: an experimental study in rabbits.
PURPOSE: To compare the anchorage of titanium implants with different surface roughness and topography and to examine histologically the peri-implant bone after implant removal. MATERIALS AND METHODS: Screw implants with five different surface topographies were examined: (1) turned ("machined"), (2) TiO2-blasted with particles of grain size 10 to 53 microns; (3) TiO2-blasted, grain size 63 to 90 microns; (4) TiO2-blasted, grain size 90 to 125 microns; (5) titanium plasma-sprayed (TPS). The surface topography was determined by the use of an optical instrument. Twelve rabbits, divided into two groups, had a total of 120 implants inserted in the tibiae. One implant from each of the five surface categories was placed within the left tibia of each rabbit. By a second operation, implants were installed in the right tibia, after 2 weeks in group A and after 3 weeks in group B. Fluorochrome labeling was performed after 1 and 3 weeks. Removal torque (RMT) tests of the implants were performed 4 weeks after the second surgery in group A and 9 weeks after the second surgery in group B. Thus, in group A, two healing groups were created, representing 4 and 6 weeks, respectively. The corresponding healing groups in group B were 9 and 12 weeks. The tibiae were removed, and each implant site was dissected, fixed, and embedded in light-curing resin. Ground sections were made, and the peri-implant bone was analyzed using fluorescence and light microscopy. RESULTS: The turned implants had the lowest Sa and Sy values, whereas the highest scores were recorded for the TPS implants. The corresponding Sa and Sy values for the TiO2-blasted implants were higher when a larger size of grain particles had been used for blasting. At all four observation intervals, the TPS implants had the highest and the turned implants the lowest RMT scores. The differences between the various TiO2-blasted implants were, in general, small, but the screws with the largest Sa value had higher RMT scores at 6, 9, and 12 weeks than implants with lower Sa values. The histologic analysis of the sections representing 6, 9, and 12 weeks revealed that fractures or ruptures were present in the marginal, cortical peri-implant bone. In such sections representing the TPS and TiO2-blasted implant categories, ruptures were frequently found in the zone between the old bone and the newly formed bone, as well as within the newly formed bone. CONCLUSIONS: The present study demonstrated that a clear relation exists between surface roughness, described in Sa values, and implant anchorage assessed by RMT measurements. The anchorage appeared to increase with the maturation of bone tissue during healing.
Animals↗
Proposed method for the standardized measurement of marginal bone height on periapical radiographs with the Brånemark System.
BACKGROUND: Strict criteria have been stipulated to evaluate success and failure of dental implants. Periapical radiographs are considered an important means of evaluation. However, there is a lack of standardized and reproducible readily available methods to carry this out. PURPOSE: The purpose of this article is to describe the manufacturing and clinical use of a simple device that enables the clinician to take parallel and reproducible periapical radiographs of dental implants. MATERIALS AND METHODS: Commercially available implant prosthetic components and film holder for periapical radiographs were modified and used clinically. RESULTS: Clinically, the device works effectively and does not require significantly more time. CONCLUSIONS: The described device is a simple appliance with an uncomplicated method to overcome problems with taking parallel and reproducible radiographs of dental implants, which is especially important when measuring marginal bone height.
Alveolar Process↗
A prospective multicenter clinical trial comparing one- and two-stage titanium screw-shaped fixtures with one-stage plasma-sprayed solid-screw fixtures.
BACKGROUND: Brånemark fixtures were originally placed in two stages, whereas titanium plasma-sprayed (TPS) solid-screws are placed in one stage. Long-term survival rates for both types of implants are excellent. Excellent survival rates have also been reported for machined screw-shaped (MS) titanium implants placed in one stage. A small number of studies have compared different implant systems and methods of implant placement. PURPOSE: The purpose of this study is to report clinical outcomes from a prospective longitudinal, multicenter study comparing Brånemark MS fixtures (Nobel Biocare, Yorba Linda, California, USA) placed in either one or two stages with a one-stage TPS system (ITI Straumann, Waldenburg, Switzerland). METHODS: A protocol was designed to compare implant survival rates, changes in crestal bone for titanium MS fixtures placed in one and two stages, and plasma-sprayed solid-screw fixtures placed in one surgical stage. Twenty-nine patients ranging in age from 24 to 82 years received MS fixtures in one stage. The average age for males was 58 years (n = 11), whereas the ages for females (n = 18) ranged from 15 to 84 years (average 58 years). Twenty-nine patients received machined titanium fixtures placed in two stages. There were 20 females ranging in age from 23 to 74 years (average 54 years) and 9 females ranging from 24 to 74 years (average 46 years). Twenty-five patients received TPS fixtures. There were 15 males, ranging in age from 57 to 79 (average 70), and 10 females, ranging in age from 40 to 83 years (average 62 years). Bone quality and quantity were determined from radiographs and during site preparation. Patient age, sex, location of implant placement according to jaw, length of fixtures, and number of lost fixtures were entered onto computer code sheets and continuously entered into a locked computer system. For one- and two-stage MS fixtures, nonstandardized periapical radiographs were taken at abutment connection and follow-up. Solid screws were x-rayed at prostheses connection and follow-up. The average time between implant restoration and radiographic follow-up was 15 months. The x-rays were scanned into a computer, and a program designed to measure radiographs was used to determine changes in crestal bone. Measurements for one- and two-stage MS fixtures were made from the top of the implant shoulder to the first bone to implant contact mesial and distally. Plasma-sprayed screws were measured from the bottom of the implant to the coronal most bone to implant contacts mesial and distally. Mesial-distal radiographic measurements were averaged and changes were compared using the t-test for related samples. RESULTS: This report presents data from the 2- to 3-year follow-up examinations. Twenty-nine patients received 80 one-stage MS fixtures. Between 0 and 1 year, two fixtures were lost, resulting in a 97.5% cumulative survival rate (CSR). The CSR remained unchanged through the 2- to 3-year follow-up. Twenty-eight patients received 78 two-stage MS fixtures. One implant was lost prior to loading and two were lost between 0- and 1-year follow-up, yielding a 96.2% CSR at the end of 1 year. The CSR remained unchanged through the 2- to 3-year follow-up. Twenty-three patients received 78 solid-screw plasma-sprayed screws. One implant was lost prior to loading and one between the 0- to 1-year follow-up, accounting for a 97.4% CSR at the 2- to 3-year follow-up. Changes in bone crest measurements for one-stage titanium threaded fixtures were insignificant (-0.11 mm, p = .08, maxillary; 0.07 mm, p = .42, mandibular). For two-stage MS fixtures, crestal bone loss was insignificant in maxillae (-0.16 mm, p = .92) and significant in mandibles (-0.43 mm, p = .000). There was significant bone loss for TPS implants in maxillae and mandibles (maxillae, 1.31 mm, p = .04; mandibles, 0.98 mm, p = .000). CONCLUSIONS: Cumulative survival rates for MS fixtures placed in one and two stages as well as one-stage TPS screws up to the 2- to 3-year follow-up examination were similar, indicating excellent clinical results. Radiographic measurements for changes in crestal bone loss were clinically insignificant for fixtures placed in one stage. For two-stage fixtures, maxillary changes were insignificant, whereas mandibular bone loss was statistically significant but clinically insignificant. Changes in crestal bone loss for TPS implants were statistically significant.
Adolescent↗
Histopathologic observations on late oral implant failures.
BACKGROUND: Despite good success rates of osseointegrated oral implants, failures do occur. To minimize losses, failure mechanisms should be elucidated. PURPOSE: This study sought to describe the morphology of tissues surrounding late failed Brånemark implants in relation to their clinical and radiographic findings to acquire a better understanding of the etiologic factors. MATERIAL AND METHODS: Ten failed implants and their surrounding tissues were consecutively retrieved from nine patients after prosthesis placement (late losses). On radiographs, a radiolucent line was visible around nine clinically mobile implants. Tightening of the abutment screw evoked pain at seven mobile implants. Clinically, no other visual inflammatory sign or symptom was manifest. A fistula originated from one stable implant, surrounded on radiographs by a diffuse bone rarefaction. Retrieved implants were electrochemically dissolved. Intact tissue-implant thin (1 micron) and ultrathin (70-80 nm) sections were analyzed with light and transmission electron microscopy. RESULTS: Peri-implant marginal tissues displayed moderate inflammatory infiltrates located adjacent to and beneath the junctional epithelium. One patient affected by oral lichen planus displayed an intense lymphocyte/plasma cell-dominated immune reaction. Deep peri-implant tissues surrounding mobile implants consisted of a dense, fibrous tissue capsule with minimal inflammation. Epithelial downgrowth was observed around four implants. Small areas of nonmineralized bone in contact with the implant were noticed in the apical portion of two implants. One implant was almost entirely colonized by bacterial plaque with the exception of its apical portion, where bone-implant contact was observed. The stable implant was characterized by bone-implant contact. CONCLUSION: Altogether clinical, radiographic, and histologic findings indicated that two major etiologic factors might have been implicated in the failure process of the investigated implants: excessive occlusal load in relation to the bone-supporting capacity and, in two cases, infection.
Aged↗
A clinical, radiographic, and microbiologic comparison of Astra Tech and Brånemark single tooth implants.
BACKGROUND: The soft tissues around single tooth implants differ fundamentally from the gingiva around natural teeth. There are very limited data comparing soft tissues around different implant systems. AIM: To assess whether the design characteristics of dental implants, particularly the implant-abutment junction, may affect the dimensions and health of the peri-implant soft tissues and radiographic bone levels. SUBJECTS AND METHOD: Fifteen Astra Tech and 15 Brånemark single tooth implants that had been in function for a minimum of 2 years in 30 partially dentate subjects were examined for plaque accumulation, probing depth, and bleeding on probing and compared to contralateral healthy teeth. Standardized radiographs were taken to measure the most coronal bone to implant contact on the mesial and distal surfaces. In addition, samples of subgingival plaque were taken on paper points and examined by darkfield microscopy. RESULTS: Significantly higher mean probing depths (p < .001) and higher mean percentage of spirochetes (p = .003) were found at implants compared to teeth. In this sample, the Brånemark implants had significantly higher probing depths than the Astra Tech implants (median and interquartile range: Astra Tech 2.7 mm [2-3], Brånemark 3.3 mm [3-3.7] p = .026) and the most coronal bone to implant contact was closer to the implant-abutment junction in the Astra Tech implants (Astra Tech 0.6 mm [0.2-0.9], Brånemark 1.6 mm [1.4-2.0]. p < .001). CONCLUSION: Although there were statistically significant differences between the two implant systems, the clinical differences were small and probably reflect differences in the biologic width in relation to the location and design of the implant-abutment junction.
Adult↗
Measurements comparing the initial stability of five designs of dental implants: a human cadaver study.
BACKGROUND: A number of different dental implant designs are currently in clinical use. A successful outcome of implant placement is thought, at least in part, to be due to the primary stability of an implant after placement. Few data are available for comparing the primary stability characteristics of different implant designs. PURPOSE: This investigation compared the primary stability of five types of endosseous dental implant of varying geometry and surface topography. MATERIALS AND METHODS: Comparison was made between a standard threaded commercially pure titanium implant (Nobel Biocare AB, Göteborg, Sweden), the Mark II self-tapping implant (Nobel Biocare AB, Göteborg, Sweden), the Mark IV tapered self-tapping implant (Nobel Biocare AB, Göteborg, Sweden), the Astra Tioblast (AstraTech AB, Mölndahl, Sweden), and the 3i Osseotite (3I [Implant Innovations Incorporated], Palm Beach, Florida, USA). Fifty-two fixtures were placed in the maxillary bone of nine unembalmed human cadavers. Implant stability as a function of peak insertion torque and resonance frequency values was recorded for each fixture site after placement. Removal torque was also measured 1-hour postinsertion. Assessment of bone quality at each site was made. RESULTS: All of the implants tested demonstrated good primary stability in type 2 and 3 bone. The Standard, Mark II, Osseotite, and Tioblast were less stable when placed into bone type 4. The Mark IV implants appeared to maintain a high primary stability even in Type 4 bone. CONCLUSION: When looking across all bone qualities, the Mark IV implant develops a significantly higher insertion torque than the Standard, Mark II, and Osseotite implant types, and a significantly higher resonance frequency value than the Standard implant, indicating a higher interfacial stiffness at the implant-bone interface.
Aged↗
Augmentation of exposed implant threads with autogenous bone chips: prospective clinical study.
BACKGROUND: Autogenous bone chips can be harvested during drilling of implant sites and may be used as a graft material for bone augmentation and coverage of exposed implant threads. PURPOSE: The aim of this prospective study was to evaluate the possibility of augmenting exposed implant threads with autogenous bone chips. MATERIALS AND METHODS: Twenty-one consecutive patients treated with screw-shaped oral implants with exposed threads due to buccal fenestration or marginal defects were augmented with autogenous bone harvested with a bone trap during drilling of the implant site. Both marginal (9 sites) and fenestration defects (12 sites), with 4 to 14 exposed implant threads, were registered clinically and with photography. The number of exposed implant threads was measured before and at second-stage surgery 6 months after augmentation. RESULTS: Complete bone coverage of the exposed implant threads was seen in 12 of the 21 implant sites. Six sites showed one to two remaining exposed threads, two showed about 40% coverage, and one showed flattening of the defect but with eight of nine exposed threads at 6 months follow-up. The mean bone gain was 81% in patients with a marginal defect and 82% in patients with a fenestration defect. CONCLUSION: The results from this clinical study show that it is possible to gain bone over exposed implant threads by augmentation with autogenous bone chips.
Adolescent↗
Interaction of force-fitting and surface roughness of implants.
BACKGROUND: Increased surface roughness may increase installation torque and thus appear to increase the initial stability of an implant. However, it is not immediately clear if the increased torque is attributable to an increase in the effective diameter of the implant or to increased resistance of the bone because of the greater roughness. PURPOSE: Force-fitting stresses arise when an implant is placed into a predrilled hole of smaller-diameter in bone. The purpose of this report is to discuss the interaction of force-fitting stresses and surface roughness effects and to develop some general guidelines as to clinical procedures based on this theory. MATERIALS AND METHODS: Solutions for the force-fitting stresses are derived from well-known equations of elasticity. RESULTS: Substantial force-fitting stresses on the order of several tens of MPa can be generated when a titanium cylinder is placed into a hole in bone, the diameter of which is only 100 microns smaller. CONCLUSION: When a hole slightly smaller than the implant diameter is prepared for implant placement, force-fitting stress increases installation torque and stability can be induced. Thus, large surface roughness of implants should not be viewed as an exclusive mechanism for providing a desirable level of initial fixity. Smaller roughness with the same mean diameter is equally effective.
Bone and Bones↗