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PubMed1996

Retrospective multicenter analysis of 3i endosseous dental implants placed over a five-year period.

Osseointegrated dental implants have now become an accepted form of treatment for patients with a fully or partially missing dentition. The purpose of this study was to evaluate the performance of 3i threaded and cylindrical implants. During a 5-year period, a total of 1969 3i endosseous implants were placed at 6 centers in the United States and 2 elsewhere in the edentulous and partially edentulous jaws of 653 consecutive patients ranging in age from 18 to 82 years. Of the total number of implants placed, 1341 were commercially pure titanium threaded implants and 628 were titanium plasma-sprayed implants with a cylindrical configuration. A total of 28 patients with 110 implants were lost to follow-up. Implants in these patients were considered neither a success nor a failure. Success was predicated on the osseointegration of each and every implant followed in this analysis rather than the persistence of prosthetic function. Confirmed bone anchorage was considered essential for success. A total of 625 patients with 1871 implants remain in the study with a follow-up period ranging from 6 to 60 months. A total of 93 implants (5.0% of the total implants followed) were considered as failures. A mean implant survival rate was 95.0% for both the threaded and the cylindrical implant was calculated. The success rate of threaded implants was 97.0% in the mandible and 93.8% in the maxilla. The success rate for the 3.3-mm cylindrical implants was 96.0% in the mandible and 95.5% in the maxilla, and the success rate of 4.0-mm-diameter cylindrical implants was 95% in the mandible and 92.0% in the maxilla. Causes of failure consisted of loss of osseointegration (2.3%), crestal bone loss requiring periodontal therapy after the first year of function (1.7%) had mechanical problems associated with the prosthesis (0.9%). This retrospective analysis of the 3i endosseous implant system is comparable to previous reports on other implant systems in terms of implant survival and prosthesis stability. It is demonstrated that 3i implants are predictable and can provide lasting osseointegration leading to improvement of oral function if the recommended surgical and restorative protocol is followed.

Adolescent↗
PubMed2002

Enhancement of primary stability of dental implants using cortical satellite implants.

PURPOSE: This study aims to assess the effect of satellite implants on the primary stability of dental implants placed in fresh extraction sites in vitro. METHOD: 34 titanium screw implants (3.75 mm x 10 mm; Bego, Bremen, Germany) were inserted in premolar- and molar-fresh extraction sites in domestic pig mandibles. Periotest (PT) values were assessed before and after insertion of one vestibular and one lingual 1.7-mm bone screw (Mondeal, Tuttlingen, Germany) as a satellite implant was connected to the implants with a 0.6-mm microplate welded to the implant abutment. RESULTS: The average PT values were 2.9 without satellite implants, -1.0 with one satellite implant, and -2.5 with two satellite implants during horizontal testing, and 3.0, 1.4, and 0.4, respectively, for vertical testing. CONCLUSION: Satellite implants increase the horizontal stability of implants in fresh extraction sites. Differences for horizontal PT assessment were significant on a 0.01 level of confidence. Implants in extraction sites may be loaded immediately, if vertical stabilization is provided by cortical bone and if horizontal PT values show sufficient stability after satellite implant insertion.

Animals↗
PubMed1995

The esthetic dental implant: letting restoration be the guide.

Dental implants originally were placed according to the availability of supportive bone structures. This article describes a new way of approaching implant placement: envisioning the ideal ultimate restoration and developing the treatment plan--and the implant site--to achieve that goal.

Alveolar Bone Loss↗
PubMed1992

Histomorphometry of bone apposition around three types of endosseous dental implants.

Three different types of commercially available dental implants (Nobelpharma, IMZ, and Integral) were implanted in the edentulous mandibles of seven adult mongrel dogs. Twenty-one implants were harvested with block sections after 12 weeks and embedded in polymethyl methacrylate resin. Undecalcified sections were prepared with the sectioning-grinding technique. The percentage of bone contacting the implant surface was measured with a self-designed histomorphometry method using a millimeter grid in a stereomicroscope. The results demonstrated a significantly higher percentage of bone along the hydroxyapatite-coated implant than that seen with the titanium-surfaced implant types.

Alveolar Process↗
PubMed1990

Tissue integration of A12O3-ceramic dental implants (Frialit)--a case report.

The tissue intraosseous integration of A12O3-ceramic dental implants (Frialit) is studied in a patient case, where an implant-fracture made it necessary to remove the implant from a patient's jaw. The surgical removing of the apical part of the implant with the use of a Trepan bur made it possible to examine and visualize histologically and microradiographically the tissue adjacent to the implant. The results of both the histological and microradiographical studies showed that a good healing and osseointegration of the ceramic dental implant (Frialit) was obtained. A direct contact was established between the implant and the surrounding alveolar bone and the induced bone tissue fitted exactly to the contour of the implant. No evidence was found of formation of a connective tissue capsule between the implant and the adjacent alveolar bone nor of any inflammatory reaction in the interface zone. In summary it was evident from the result of the present study that the biocompatibility properties of pure aluminoxide ceramics (A12O3) are excellent and can be recommended as an acceptable alternative among the many different implants, that now are available on the market.

Adult↗
PubMed1995

Finite element analysis of crestal bone loss around porous-coated dental implants.

Crestal bone loss is observed around various designs of dental implants. A possible cause of this bone loss is related to the stresses acting on periimplant bone. To investigate the relationship between stress state and bone loss, two-dimensional finite element models corresponding to bucco-lingual and mesio-distal sections of canine mandibles with one of two designs of porous-coated dental implants were analyzed. A fully porous-coated design consisting of a solid Ti6A14V core had a porous coating over the entire outer surface of the implant component, while a partially porous-coated design had the porous coating over the apical two-thirds of the implant surface only. Occlusal forces with axial and transverse components were assumed to act on the implant with interface bonding and effective force transfer at all porous coat-bone interfaces and no bonding for the non-porous-coated regions. The results of the analysis indicated that at most implant aspects (buccal, lingual, mesial, and distal), the equivalent stresses in crestal bone adjacent to the coronal-most, non-porous-coated zone of the partially porous-coated implants were lower than around the most coronal region of the fully porous-coated implants. The region of lower stress around the partially porous-coated implants corresponded to observed areas of crestal bone loss in animal studies, suggesting that crestal bone loss in this case was due to bone disuse atrophy. A number of parameters of the finite element models were varied to determine the effect on the resulting stress fields and, therefore, possible long-term bone remodeling. Based on differences in observed bone structures by histological examination and results of finite element analyses with fully and partially porous-coated implants, an equivalent stress equal to 1.6 MPa was determined to be sufficient to avoid bone loss due to disuse atrophy in the canine mandibular premolar region.

Alloys↗
PubMed2001

[Magnetic resonance tomography for planning dental implantation].

PROBLEM: Three-dimensional imaging diagnostics are increasingly recommended before inserting dental implants in high-risk areas and in cases of severe alveolar atrophy. Since patients are exposed to considerable radiation with computed tomography (CT), the possibilities of employing magnetic resonance imaging (MRI) of the jaw as a diagnostic imaging method before inserting dental implants were examined. MATERIAL AND METHOD: Twelve patients and three volunteers were examined by MRI with T1-weighted, fat-suppressed sequences and conventional T1-weighted sequences. The patients wore a diagnostic splint including markers--in the form of capillaries filled with 0.025 x 10(-2) M gadolinium solution (1.5 mm in diameter)--in the planned implant's position and axis. RESULTS: The presentation of relevant anatomic structures and the three-dimensional accuracy of the markers were judged. Metal artefacts were evaluated in vitro. The MRI of the jaw and midface represents the mandibular canal, the maxillary sinus, and other decisive anatomic structures by detailed representation of the connective tissue surrounding the bone. Artefacts of metallic fillings reduce the image quality. CONCLUSION: Obtaining clinical findings and planning before inserting dental implants with the help of MRI can certainly be applied with toothless patients and facilitates three-dimensional planning by representing the exact location and angle of the drill tubes. Local restrictions result from metal extinction artefacts in jaws with teeth and in controls after having inserted titanium implants.

Adolescent↗
PubMed2006

Identification of dental implants through the use of Implant Recognition Software (IRS).

AIM: To develop computer software to allow general dental practitioners and others to identify unidentified implants in patients' mouths using a range of criteria. METHODS: Internet searches for implant manufacturing companies worldwide in all languages using terms: dental implants, dental implant manufacturers and dental implant companies. Once identified, all relevant information including images regarding dental implant products was collected even that for discontinued products. A program was then devised using key design factors to enable identification of individual implants. RESULTS: The searches produced details for 87 implant manufacturers based in 21 countries with 231 different implant designs. The resultant program has been successfully trialled and used in both general dental practice and for forensic identification. CONCLUSION: The program developed provides a valuable adjunct to the identification of implant systems present in patients' mouths.

Dental Implants↗
PubMed1999

Contact angle measurement on dental implant biomaterials.

Wettability may be one of the surface factors to be considered when selecting dental implant biomaterials. Contact angles of dental implant surface preparations influence wettability and tissue adhesion. The contact angles of eight implant surface preparations were determined in this study. Contact angles were measured by a tele-microscope equipped with a protractor eyepiece. Groups 1 to 6 had a Ti6Al4V substrate. Group 1 was metallurgically polished, group 2 was blasted with 180 microns Al2O3, group 3 was blasted with 710 microns Al2O3, group 4 was hydroxyapatite (HA) blasted (125 microns), group 5 had a Calcitite HA plasma-sprayed coating, and group 6 was coated with plasma-sprayed MP-1 HA. Group 7 was metallurgically polished commercially pure (CP) titanium (grade 1), and group 8 was etched CP titanium (grade 1). Contact angles were measured 30 times for each group with distilled water and glycerol, and the determinations were statistically analyzed. Mean contact angles for groups 1 to 8 were 65.5, 65.3, 62.5, 67.9, 46.6, 81.7, 58.5, and 69.0, respectively, when tested with distilled water, and 70.7, 68.3, 81.6, 75.4, 67.1, 70.7, 62.3, and 82.5, respectively, when tested with glycerol. Analysis of variance and Tukey's Honestly Significant Difference test (p = 0.05) demonstrated significant differences between group 5 and all other groups when groups were tested with distilled water and demonstrated no significant differences between groups 5 and 7 when groups were tested with glycerol. Surface preparation of implant biomaterials affects wettability. In this study, Ti6Al4V coated with Calcitite HA had the lowest contact angles and the best wettability.

Alloys↗
PubMed1997

A comparative study of flexible (Polyactive) versus rigid (hydroxylapatite) permucosal dental implants. I. Clinical aspects.

Recently, an elastomeric polyethyleneoxide polybutylene-terephthalate (PEO:PBT) copolymer (Polyactive) was introduced, which exhibits bone-bonding characteristics. In contrast to ceramics, bioglass, titanium and other metals, PEO:PBT copolymers are flexible materials that could reduce undesirable peak stresses along the neck of a permucosal implant. The application of three types of Polyactive permucosal dental implants (one dense and two porous types) and one dense hydroxylapatite (HA) implant were clinically tested and compared during 30 weeks of loading in a dog experiment. With respect to the porous Polyactive implants, it was observed that the pore diameter had decreased to such an extent that optimal bone ingrowth was not achieved. Polyactive is known to expand due to water uptake, and, as a consequence, the sizes of the pores of the press-fit inserted implants had decreased to a large extent. This feature explained the high loss of the implants with the porous outer layer (6 out of 22). None of the dense Polyactive implants and only one of the HA implants were lost. Statistical analysis was performed solely on the dense Polyactive and the HA implants. At the lingual sites, plaque scores, gingiva indices, bleeding indices and corresponding pocket depths were statistically significantly lower for both implant types, when compared to the corresponding values at the buccal, mesial and distal sites, irrespective of the observation period. Differences between the dense Polyactive and the HA implants were not observed. A considerable difference in mobility was registered between the Polyactive and the hydroxylapatite implants, as measured by the Periotest. The dense Polyactive implants functioned adequately and had mobility resembling natural teeth. As such, these dense flexible materials showed a favourable clinical function and they seem promising for reducing undesired peak stresses when applied as a dental implant.

Analysis of Variance↗
PubMed1990

The influence of materials difference on stress distribution and bone remodeling around alumina and titanium dental implants.

The long-term complications of dental implants are associated with loosening of the implant-bone interface, due to bone resorption and subsequent connective tissue interposing at the implant-bone interface. Mechanical stresses, which are induced in the surrounding bone, play a key role in the interface bone remodeling. In the present study, it is investigated how local stress patterns are associated with local bone structure. For identical geometry alumina, and titanium implants, the stress patterns, determined in the finite element models with boundary conditions, are compared with the local bone structure found in animal experiments. The results indicate that there appears to be relationship between the stress patterns and the bone remodeling at the implant-bone interface independently on the materials properties in alumina and titanium.

Aluminum Oxide↗
PubMedDate not supplied

Radiologic study of marginal bone loss around 108 dental implants and its relationship to smoking, implant location, and morphology.

PURPOSE: To investigate peri-implant bone resorption around 108 ITI dental implants 1 year after prosthetic loading using extraoral panoramic, conventional intraoral periapical, and digital radiologic techniques. MATERIALS AND METHODS: A total of 108 implants were placed (59 in the maxilla and 49 in the mandible) in 42 patients (16 men and 26 women) with a mean age of 44.2 years (range 14 to 68 years). Orthopantomographic, conventional periapical, and digital radiographs were obtained at loading and again 1 year later. Bone loss was calculated from the difference between the initial and final measurements. RESULTS: Mean loss in alveolar bone height was determined to be 1.36 mm by extraoral panoramic radiography, 0.76 mm by intraoral periapical radiography, and 0.95 mm by digital radiography. The implants located in the maxilla and those placed in patients who smoked 11 to 20 cigarettes per day were associated with significantly greater bone loss. DISCUSSION: The results in relation to peri-implant bone loss in the first year after loading were similar to those published by other authors. CONCLUSION: Conventional periapical films and digital radiographs were more accurate than orthopantomography in the assessment of peri-implant bone loss. Smoking and implant location in the maxilla were associated with increased peri-implant marginal bone resorption.

Adolescent↗
PubMed1999

Clinical experience with one-stage, non-submerged dental implants.

This review article describes the scientific documentation of one-stage, non-submerged dental implants. In the past 25 years, numerous in vivo studies have demonstrated that non-submerged titanium implants achieve osseointegration as predictable as that of submerged titanium implants. This observation was confirmed in prospective clinical studies, mostly done with the ITI Dental Implant System. ITI implants have been widely documented for up to 10 years of prospective follow-up at various centers. All studies showed success rates well above 90%. In summary, the non-submerged approach is a true alternative to the original healing modality with submerged titanium implants. The non-submerged approach offers several clinical advantages: (i) the avoidance of a second surgical procedure and less chair time per patient, resulting in overall reduced treatment cost; (ii) the lack of microgap at the bone crest level, leading to less crestal bone during healing and resulting in a more favorable crown-to-implant length ratio; and (iii) a simplified prosthetic procedure, presenting an ideal basis for cemented implant restorations. Due to these significant clinical advantages, the non-submerged approach will become more important in implant dentistry in the near future, particularly in implant sites without esthetic priority.

Alveolar Process↗
PubMedDate not supplied

Numerical analysis of a dental implant system preloaded with a washer.

Gold screw loosening is a problem that frequently affects dental implants. The application of a preload has been the main means of preventing loosening. However, this measure has not been able to eliminate its occurrence. In this study the effect of a washer in a Brånemark-type implant on the loosening conditions of the retaining screw was investigated using a finite element simulation. The simulation indicated that a washer may significantly increase the tolerance of a screw against loosening. This is accomplished by increasing the tolerance of the implant against deformation. The addition of a customized washer to a dental implant system may offer a very simple and inexpensive solution for the persistent problem of screw loosening.

Dental Abutments↗
PubMed2004

Efficiency considerations for the purely tapered interference fit (TIF) abutments used in dental implants.

A tapered interference fit provides a mechanically reliable retention mechanism for the implant-abutment interface in a dental implant. Understanding the mechanical properties of the tapered interface with or without a screw at the bottom has been the subject of a considerable amount of studies involving experiments and finite element (FE) analysis. In this paper, approximate closed-form formulas are developed to analyze the mechanics of a tapered interference fit. In particular, the insertion force, the efficiency, defined as the ratio of the pull-out force to insertion force, and the critical insertion depth, which causes the onset of plastic deformation, are analyzed. It is shown that the insertion force is a function of the taper angle, the contact length, the inner and outer radii of the implant, the static and the kinetic coefficients of friction, and the elastic modulii of the implant/abutment materials. The efficiency of the tapered interference fit, which is defined as the ratio of the pull-out force to insertion force, is found to be greater than one, for taper angles that are less than 6 deg when the friction coefficient is 0.3. A safe range of insertion forces has been shown to exist. The lower end of this range depends on the maximum pull-out force that may occur due to occlusion in the multiple tooth restorations and the efficiency of the system; and the upper end of this range depends on the plastic deformation of the abutment and the implant due to interference fit. It has been shown that using a small taper angle and a long contact length widens the safe range of insertion forces.

Animals↗
PubMed1997

Impulse response of a dental implant in bone by numerical analysis.

The osseointegration process of titanium dental implants in bone has been simulated previously using natural frequency and impulse excitation. However, the impulse strength was arbitrarily chosen and may not have yielded the correct frequencies and displacements to be compared with those measured in a clinical situation. In this work the range of impulse excitation strengths applied to a dental implant osseointegrated in bone and the corresponding response have been examined using the finite element method. Both conditions of a dental pin only and a dental pin with attached cantilever integrated in the mandible have been examined. The dynamic analysis indicated that the frequency and displacement responses are indeed sensitive to impulse duration and direction but independent of impulse load. The analysis summarizes the proper impulse excitation values for a correct interpretation of clinically measured frequency response data.

Biomechanical Phenomena↗
PubMedDate not supplied

Finite element stress analysis of the influence of staggered versus straight placement of dental implants.

Bending moments resulting from non-axial overloading of dental implants may cause stress concentrations exceeding the physiologic supporting capacity of cortical bone, leading to various kinds of failures. The aim of this study was to evaluate the effect of staggered (offset, tripodization) implant placement configuration and placement of wider-diameter implants in a straight-line configuration in mandibular posterior edentulism. A mandibular Kennedy Class II partially edentulous finite element model was constructed. Seven different partial fixed prostheses supported by 3 implants were designed according to 2 main configurations: straight-line or staggered implant placement. In 5 of the designs, implants with various diameters and length were placed along a straight line. In the other 2 models, offset placement of the middle implant buccally and lingually was simulated. A 400 N static load was applied perpendicular to the buccal inclination of the buccal cusps on each unit. Tensile and compressive stress values on cortical bone in the cervical region of the implants were evaluated. Lower stress values were recorded for the configuration with wider implants placed in a straight line. Other configurations, including staggered implant placement, produced similar stress values. Despite the offset implant placement, the stresses were not decreased; however, straight placement of wider implants may decrease bending moments.

Compressive Strength↗