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The effect of surface macrotexture on the mechanical and histologic characteristics of hydroxylapatite-coated dental implants.

The interface attachment strength and histology of HA-coated endosseous dental implants with surface texturing added to allow for mechanical interlocking of the implant to bone were evaluated in the canine mandibular model. Twenty-two adult mongrel dogs received eight implants (four per side) placed into healed extraction sites. Fifteen weeks post-implantation, the implants were evaluated mechanically by axial pull-out and torsional testing. Following testing, the specimens were evaluated quantitatively for histologic parameters of bone apposition, HA-coating thickness, and mode of interface failure. The addition of surface macrotexture (threads, grooves, and dimples) was not found to have a significant effect on axial pull-out strength compared with smooth implant controls. Similarly, mechanical testing in torsion failed to reveal any significant effect on implant-bone interface attachment due to surface macrotexture. Interface failure occurred primarily at the HA/substrate interface in all implant designs. Examination of HA-coating thickness revealed non-uniform coatings, particularly in the surface-textured designs. Although bone growth into the surface textures was observed in some cases, often only minimal or a thin osseous layer on the HA coating was observed. This factor most likely contributed to the lack of significant additional interface attachment strength in the textured designs. The reduction in areas of complete implant incorporation may also have exposed the HA coating to high interfacial loads and may be responsible for the greater HA coating break-up and presence of particles observed in the textured designs.

Animals↗

Biodegradable dental implants of ciprofloxacin beta-cyclodextrin inclusion complex in the treatment of periodontitis.

Dental implants of ciprofloxacin beta-cyclodextrin inclusion complex were formulated using poly (epsilon-caprolactone), a biodegradable polymer and evaluated. Clinical evaluation was carried out in ten patients with acute peridontitis. Various clinical parameters, viz. gingival index, plaque score, attachment gain, reduction in pocket depth were evaluated at 10, 20, 30, 40 days of treatment and compared with placebo as control. A significant (P < 0.0001) improvement in the healing of periodontal pockets treated with ciprofloxacin beta-cyclodextrin implant was observed in most of the clinical parameters. Estimation of gingival crevicular fluids (GCF) for the drug content revealed that drug levels above the minimum inhibitory concentration (10.2 micrograms/mg) for many of the periodontal pathogens were maintained throughout the period of study (40 days). This confirms the clinical efficacy of the dose and the duration of the study. It was found that biodegradable carrier was better accepted than the non-biodegradable carriers reported earlier.

Adult↗

Properties of titanium dental implants produced by electro-discharge compaction.

Highly porous dental implants of a cylindrical shape were fabricated from commercial grade titanium REP-atomized powders by EDC. They were intended to have the maximum porosity for maximum osseointegration, but to maintain the minimum mechanical properties functionally required. Two level full factorial experiments were conducted with respect to the sample weight, capacitance, input energy and electrode configuration. All samples were X-rayed prior to tests to ascertain the presence, extent and distribution of internal macroscopic voids. Torque and compression tests were conducted to evaluate the yield or ultimate strengths (34-90 cm N and 205-502 MPa, respectively). These results indicate that macroscopic void-free, highly porous implants can be fabricated.

Dental Implants↗

Kaplan-Meier analysis of dental implant survival: a strategy for estimating survival with clustered observations.

The study's purposes were to estimate dental implant survival in a statistically valid manner and to compare three models for estimating survival. We estimated survival using three different statistical models: (1) randomly selecting one implant per patient; (2) utilizing all implants, assuming independence among implants from the same subject; and (3) utilizing all implants, assuming dependence among implants from the same subject. The cohort was composed of 660 patients who had 2286 implants placed. Due to the high success rates of implants, the five-year survival point and standard error estimates varied little among the three models. Patients at high risk for implant failure (smokers) manifested greater variation in the standard error estimates among the three models, 8.2%, 4.0%, and 5.6%, respectively. To obtain statistically valid survival confidence intervals when performing Kaplan-Meier survival analyses, we recommend adjusting for dependence when there are multiple observations within the same subject.

Dental Implantation, Endosseous↗

Changes in patient screening for a clinical study of dental implants after increased awareness of tobacco use as a risk factor.

Independent external monitoring committees are an important part of scientific clinical trials. They monitor patient safety, study progress, investigators' performance, and accurate interpretation/reporting of the study data. Data trends observed by a study monitoring committee detected a change in the pattern of patient screening by investigators after an increased awareness that tobacco use could directly compromise the osseointegration of root-form dental implants. This increased awareness is believed to have altered the number of active smokers accepted into a multicenter prospective dental implant study. Recent data analyses indicate that the success ratios were improved by alterations in this discretionary inclusion-exclusion criterion.

Data Interpretation, Statistical↗

Improved method using a bubble-free adhesion technique for the preparation of semi-serial undecalcified histologic sections containing dental implants.

The preparation technique, with the minimum of artifacts for the semi-serial undecalcified histologic sections containing dental implants, is presented in this study. The sections enabled finer light-microscopic observations to be made. A formalin-fixed tissue block containing a dental implant was dehydrated in ethanol and acetone, and then embedded in polyester resin under 76 cm Hg reduced pressure. The embedded block was trimmed by a cutter and ground by abrasive paper. In a 1.5 Kg f/cm2 pressurized chamber, its polished surface was bonded to a methacrylate slide by means of ethylcyanoacrylate used in an adhesion loading device. This meant that no bubbles could arise in the interface between the slide and the block. The slide-block was then attached to an adsorptive specimen-holder of a hard-tissue cutting machine and cut to a thickness of approximately 50 microns, with use of a diamond blade. The slide-section was ground to 15-40 microns with wet-type abrasive paper and film on a polishing table. Etching with weak acid and surface staining with toluidine blue and methylene blue/basic fuchsin/light green were performed on the section.

Acrylic Resins↗

Variability of hydroxyapatite-coated dental implants.

Uniformity, surface roughness, and chemical phase structure are all important features of implant coatings. While the first two variables are important for implant placement, the phase structure affects implant fixation. This study examined the coating morphology and the amount, size, and distribution of crystalline regions of press-fit and screw-type dental implants. Implants obtained from five commercial vendors were sectioned sagittally, mounted, and polished to reveal the coating microstructure. The crystalline phase content varied depending on the implant supplier; however, general trends were observed. Amorphous regions were predominantly found at the metal interface and decreased toward the outside of the coating, producing a crystallinity graded coating. The distal end of the implant, where heat build-up was more likely during the coating procedure, displayed a higher crystalline content and larger crystalline regions. Similarly, the thread apex consisted of more of a crystalline phase. The results of this study of coating microstructure may be used to improve the quality and performance of implants and may help to explain different in vivo responses to the many available varieties of hydroxyapatite-coated dental implants.

Coated Materials, Biocompatible↗

A radiographic evaluation of bone healing around submerged and non-submerged dental implants in beagle dogs.

BACKGROUND: The rehabilitation of the oral cavity with dental implants has become a predictable treatment modality. However, there have been only a few direct comparisons evaluating the submerged and nonsubmerged placement techniques. The purpose of this study was to characterize radiographic peri-implant bone changes following the insertion of submerged and nonsubmerged implants in the beagle dog. METHODS: At the end of the extraction healing phase, 19 submerged and 19 nonsubmerged implants were randomly placed in a split-mouth study design and observed over an 18-week period. For submerged implants, a second stage surgery and transmucosal abutment attachment was performed at week 12. Standardized dental radiographs taken at baseline, week 12, and week 18 were used to measure peri-implant bone changes. The radiographs were analyzed with a simple computer assisted method. RESULTS: A total of 43 standardized radiographs were exposed to evaluate the 38 implants. During the study period, all submerged and nonsubmerged implants demonstrated peri-implant bone loss. At baseline, both submerged and nonsubmerged implants had similar bone levels (P > or = 0.05). When the mean peri-implant bone levels for submerged and nonsubmerged implants were compared from baseline to week 12, nonsubmerged implants had a significantly greater amount and rate of bone resorption than submerged implants (P < or = 0.05). Following week 12, the initially submerged implant had a significantly higher rate and amount of peri-implant bone loss than the nonsubmerged implants (P < or = 0.05). However, by the end of the study period, week 18, both submerged and nonsubmerged implants had comparable bone levels (P > or = 0.05). CONCLUSIONS: The study indicates that, although the temporal patterns of peri-implant bone resorption differed, there were no differences between submerged and nonsubmerged implants in the overall amount and rate of peri-implant bone loss.

Alveolar Process↗

Dental implants in the esthetic zone. Considerations for form and function.

Successful esthetic results of dental implant placement in the esthetic zone require knowledge of various concepts and techniques. Careful preoperative treatment planning, augmentation of hard and soft tissues, and attention to the details of implant surgical and prosthetic techniques are areas that must be addressed when treating the anterior maxilla. This article will address the fundamental considerations related to implant treatment in the anterior maxillary esthetic zone, using both theory and case examples.

Bone Transplantation↗

Simplifying management of the posterior maxilla using short, porous-surfaced dental implants and simultaneous indirect sinus elevation.

This article describes the use of short, porous-surfaced root-form dental implants and an indirect, simultaneous, osteotome-mediated sinus elevation procedure to restore the posterior maxilla when as little as 3 mm of bone remain below the sinus floor. Results with 16 patients who are part of an ongoing prospective clinical trial using the Endopore implant show 100% success (using established criteria) with a mean implant length of 6.9 mm and a mean functional time of 11.1 months. This treatment approach greatly simplifies the management of the posterior maxilla with minimal bone height below the sinus floor.

Bone Density↗

[Study on method for examining bone quality for dental implant. Relationship between cutting force and bone mineral content].

A number of factors, including, for example, patient jawbone condition, influence prognosis of dental implants. At present, X-ray and intraosseous punctures are employed as means of examining bone quality. But lack of definite criteria makes objective evaluation difficult. In order to develop a more reliable method for making objective evaluations of bone quality for dental implant, this study quantitatively measured the cutting force at an intraosseous puncture and investigated its relation to bone mineral content, a parameter of bone condition. Methods One side of each of 4 mandibles obtained from adult Japanese cadavers was fixed with formalin. The mandibles were free of deformity and injury to the jaw or face but lacked molars (these materials were the property of the Department of Anatomy, the Tokyo Dental College). Drilling tests were made in 5 samples taken from each of the 4 mandibles (20 in all), and bone mineral content was measured. Prior to the drilling test, the dental engine was remodeled to produce an experimental test machine permitting quantitative measurement of the cutting force (cutting torque) exerted on cutting instrument in the direction of rotation. The device was fitted to a universal testing machine and constant-feed-speed drilling tests were performed. Cutting force on the cutting instrument produced during drilling was divided into cutting torque (cm-g) in the direction of rotation and cutting load (gf) in the direction of feeding. Densitometry and image analysis were used to measure bone mineral content. X-ray photograph were taken from each sample with an aluminum reference, the density of which was digitalized and measured. The density value was then image analyzed, and bone mineral content of the drilled site was obtained as relative value calculated in aluminum equivalent (mmAl). Comparative examinations of cutting torque, cutting load, and bone mineral content were made through the same drilled site at every 1.0 mm-depth from surface. Results and Conclusions 1. The experimental test machine permitted quantitative measurements of the cutting force exerted on the cutting instrument in the direction of rotation (cutting torque). 2. Quantitative measurements on the cutting force during drilling produced the following values: cutting torque--0.4 to 56.5 cm-g with an average of 8.7 cm-g; cutting load--1.7 to 1419.7 gf with an average of 169.3 gf. 3. Bone mineral content at the drilled site ranged from 0 to 0.67 mmAl and averaged 0.19 mmAl.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

Dynamics of dental implants and orthodontics in today's periodontal prosthesis.

Periodontal prosthesis refers to multidisciplinary efforts to stop disease progression, correct deformities created by dental diseases, and establish a therapeutic occlusion to restore the form and function of the masticatory system. These efforts are critical for the long-term prognosis and maintenance of the guarded teeth and the overall prosthesis. This article presents a functionally and esthetically challenging case, which illustrates a multidisciplinary approach--specifically implantology and orthodontics--and how they impact on each other during treatment. The role and importance of dental implants and orthodontics in setting up a case is illustrated in this article.

Alveolar Bone Loss↗

Osseointegrated dental implants in conjunction with bone grafts.

This paper relates to the experience with 12 patients who received osseointegrated dental implants of the Branemark design associated with bone grafts. 4 patients had iliac crest grafts, 2, of which were inserted together with the implants. Two had metatarsal reconstruction of the anterior mandible with the implants installed at a later date. 2 patients had particulate marrow grafts with immediate installation of the implants. Of the remainder, 1 had a late implantation of a myo-osseous flap utilizing the clavicle and the other delayed implantation of a split rib graft. The mean age of the patients in this series is 49.5 years. The mean loading time for completed cases is 18 months. 7 patients have had their dentition successfully restored, 3 lost the initial implants, 2 of which have been re-operated. One patient died prior to loading and one awaits the final surgical procedure. The results of the particulate marrow and split rib grafts were disappointing. The remainder suggest that osseointegrated dental implants may be utilized with appropriate bone grafting techniques to restore the dentition in patients with severe bone loss or following the surgical ablation of malignant disease.

Adult↗

In vitro investigation of titanium and hydroxyapatite dental implant surfaces using a rat bone marrow stromal cell culture system.

In this study, rat bone marrow cells (RBM) were used to evaluate different titanium and hydroxyapatite dental implant surfaces. The implant surfaces investigated were: a titanium surface having a porous titanium plasma-sprayed coating (sample code Ti-TPS), a titanium surface with a deep profile structure (sample code Ti-DPS), an uncoated titanium substrate with a machined surface (sample code Ti-ma) and a machined titanium substrate with a porous hydroxyapatite plasma-sprayed coating (sample code Ti-HA). RBM cells were cultured on the disc-shaped test substrates for 14 days. The culture medium was changed daily and examined for calcium and phosphate concentrations. After 14 days specimens were examined by light microscopy, scanning electron microscopy, energy dispersive X-ray analysis and morphometry of the cell-covered substrate surface. All test substrates facilitated RBM growth of extracellular matrix formation. Ti-DPS and Ti-TPS to the highest degree, followed by Ti-ma and Ti-HA. Ti-DPS and Ti-TPS displayed the highest cell density and thus seem to be well suited for the endosseous portion of dental implants. RBM cells cultured on Ti-HA showed a delayed growth pattern. This may be related to its high phosphate ion release.

Animals↗

Histology of tissues surrounding single crystal sapphire endosseous dental implants: an experimental study in the beagle dog.

9 single crystal sapphire dental implants were installed bilaterally into pre-extracted areas in the lower jaw of two beagle dogs and histologically analysed after 180 days in situ. 8 implants were stable and radiographs disclosed complete bone healing. Light-, scanning- and transmission electron microscopy demonstrated that the stable implants were surrounded by a mineralizing bone boundary and a mucosa nearly free from inflammatory cell infiltrations. The 9th implant was mobile and surrounded by a non-mineralized connective tissue capsule containing bundles of collagen. The ultrastructure of the mucosa surrounding the implants closely resembled the mucosa surrounding the tooth. Histometric analysis of the alveolar bone surrounding the stable implants revealed that the value of the bone contact surface ranged from 37.1% to 86.9% (mean value 61.8%) at the light microscopic level.

Alveolar Process↗

A novel computational method for real-time preoperative assessment of primary dental implant stability.

A novel methodology which allows for fast and fully automatic structural analysis during preoperative planning for dental implant surgery is presented. This method integrates a fully automatic fast finite element solver within the framework of new concepts in computer-assisted preoperative planning for implant surgery. The planning system including optimized structural planning was validated by experimental results. Nine implants were placed in pig mandibles and mechanically loaded using a testing rig. The resulting displacements were measured and compared with those predicted by numerical analysis during planning. The results show that there were no statistically significant differences (P = 0.65) between the results of the models and the experiments. The results show that fast structural analysis can be integrated with surgical planning software allowing the initial axial implant stability to be predicted in real time during planning. It is believed that such a system could be used to select patients for immediate implant loading and, when further developed, be useful in other areas of preoperative surgical planning.

Animals↗

Factors affecting crestal bone loss with dental implants partially covered with a porous coating: a finite element analysis.

Limited crestal bone loss has been observed around dental implants partially covered with a porous coating. The results of a two-dimensional finite element analysis suggested that for this implant design, the observed crestal bone loss is the result of low stresses acting on bone around the uncoated superior region of the implant, causing disuse atrophy of bone. This finite element study investigated the effect on crestal bone loss of varying the design of the prosthesis connecting pairs of implants, the length of the uncoated region of the implant, and the friction at the noncoated coronal portion of the implant and adjacent host bone.

Alloys↗