Clinical and histologic evaluation of an active "implant periapical lesion": a case report

A new entity called "implant periapical lesion" has recently been described. This lesion could be the result of, for example, bone overheating, implant overloading, presence of a preexisting infection or residual root fragments and foreign bodies in the bone, contamination of the implant, or implant placement in an infected maxillary sinus. This case report describes a titanium implant that was placed in the maxillary premolar region. A fenestration involving the middle portion of the implant was present. After 7 months, the apical portion of the implant showed radiolucency. This lesion rapidly increased in size and a vestibular fistula appeared. A systemic course of antibiotics was not successful, and the implant was then removed. The histologic examination showed the presence of necrotic bone inside the antirotational hole of the implant. The etiology of the implant failure in this instance could possibly be related to bone overheating associated with an excessive tightening of the implant and compression of the bone chips inside the apical hole, producing subsequent necrosis.     

Reversibility of medialization laryngoplasty. An experimental study

Medialization laryngoplasty has become a routine procedure for cases of unilateral vocal fold paralysis. In certain clinical situations, it may become desirable to reverse the procedure and remove the implant. This process was studied experimentally in eight dogs in a chronic model of induced canine phonation. A silicone polymer implant was inserted to medialize one normal vocal fold for a period of 1 month, after which it was removed. Motion of the cricoarytenoid (CA) joint and induced phonation were studied weekly while the implant was in place, and for another month following implant removal. Significant abnormalities were found even with this relatively short period of implantation. With the implant in place, impairment of CA joint mobility was found in seven of the eight dogs, precluding phonation. A dense fibrous capsule rapidly developed around the implant, making its removal technically difficult. Following implant removal, a gradual return to normal function was found in only three of the eight dogs. One of the animals had evidence of neural injury, while four had intact neural function but impaired mobility or fixation of the CA joint. Medialization laryngoplasty should not be considered a reversible procedure. The clinical implications of these findings are discussed.     

Acute liver failure

PURPOSE: This article reviews the literature on radiographic imaging techniques and image interpretation for dental implant treatment. MATERIALS AND METHODS: MEDLINE was used to identify published peer-reviewed literature for this report. RESULTS: Radiographic images are indispensable in the evaluation of osseous structures when planning treatment for dental implants. Potential bone sites for implant placement can be assessed clinically by means of palpation or probing through the mucosa; however, diagnostic imaging provides the best means for indirectly measuring bone dimensions. After healing of the implant site, the application of radiology is useful to verify the amount of bone adjacent to the implant and that the transmucosal abutments fit the implant. Upon completion of the implant prosthesis, radiology may be used to monitor initial and long-term success of implant treatment. CONCLUSION: Recommendations for the application of radiology over the course of treatment are made for various implant cases ranging from the overdenture to the single-tooth implant.     

Breast capsule persistence after breast implant removal

Breast implant capsules are a foreign body immune response to breast implants. It has been proposed that capsulectomy after breast implant removal was unnecessary, as the body resorbs the capsule when the implant, the impetus for the foreign body response, is removed. We report eight women with persistent capsules 10 months to 17 years after silicone breast implant removal.     

Aseptic loosening of the femoral implant after cemented total hip arthroplasty in dogs: 11 cases in 10 dogs (1991-1995)

Aseptic loosening of the femoral implant (ALFI) was diagnosed in 10 dogs that had undergone cemented total hip arthroplasty (THA). One dog had bilateral ALFI. Loosening developed at the stem-cement interface a mean of 30 months after THA. The most common clinical sign was intermittent subtle or non-weight-bearing lameness. On radiographs obtained after THA, the distal stem tip was in contact with the cortical endosteum in all dogs. Radiographic changes at the time of diagnosis of ALFI included asymmetric periosteal reaction along the femoral diaphysis (n = 11), radiolucent zone at the stem-cement interface (6), altered implant position (4), and femur fracture (1). Surgical revision resulted in a good or excellent outcome in 9 dogs. In 1 dog, the implant became infected. In another, aseptic loosening recurred. Aseptic loosening of the femoral implant was significantly more common when initial positioning of the implant resulted in contact between the distal tip of the implant and cortical endosteum than when there was no contact.     

In vitro attachment of human gingival fibroblasts to endosseous implant materials

In recent years, the focus of dental implant research has been the nature of the bone-implant interface associated with osseointegration, yet the transgingival portion of endosseous dental implants has received little attention. The purpose of this study was to determine the attachment of human gingival fibroblasts to three different implant materials: commercially pure titanium, non-porous hydroxyapatite, and porous hydroxyapatite. Cell attachment was quantified by radiolabeling gingival fibroblasts with tritiated thymidine and counting attached cells by liquid scintillation following incubation for periods of 20, 40, and 60 minutes. Additional studies coating implant surfaces with fibronectin were also performed. The nature of the implant material itself appeared to affect the number of attached cells. Determined on a surface area basis, fibroblast attachment was greatest to titanium followed by non-porous hydroxyapatite. Porous hydroxyapatite demonstrated the least amount of fibroblast attachment. When incubated with fibronectin at a concentration of 50 micrograms/ml, no increase in the number of cells attached to the various implant materials was observed. A small but statistically significant increase in the number of fibroblasts attached to porous hydroxyapatite at 40 minutes was observed when implant materials were pre-treated with fibronectin.     

Speech-evoked cognitive P300 potentials in cochlear implant recipients

The cognitive P300 evoked potential was elicited by speech stimuli in successful cochlear implant recipients, and the resulting P300 morphology was remarkably similar to that of normal-hearing individuals. The P300 was elicited by the synthesized speech pair/da/and/di/ presented using an oddball paradigm to nine "good" Nucleus cochlear implant users and nine age-matched normal-hearing subjects (34-81 yr old). There were no significant differences in P300 amplitude and latency between the two groups. Moreover, the N1 and P2 potentials occurred at similar latencies in the two groups, although the N1 amplitude was significantly smaller in the cochlear implant users. The P300 was absent in one "poor" cochlear implant user. The results suggest that the P300 may serve as a useful tool for evaluating the cognitive aspects of auditory processing in cochlear implant recipients, and that it may aid in assessing the success of cochlear implantation.     

The Spline implant interface: analysis and initial clinical experiences

A new implant with a spline-shaped interface (Spline) was recently introduced. A common and preferred method of connecting two cylinders in many fields of industry, the Spline offers implant dentistry improved strength and precision compared to earlier and current implant connection designs. A comparative engineering analysis of the Spline and the major implant interfaces is offered, including the possible clinical implications. Initial surgical and restorative experiences with cement and screw-retained prostheses are presented in case reports.     

Significant reduction in circuit pressure with modified plasma separation chamber for a heparin removal device

OBJECTIVE: This study aimed to determine the maximum dose of radiation the CLARION 1.2 cochlear implant can withstand safely. INTRODUCTION: Cochlear implants restore functional hearing to patients with sensorineural deafness. Because some patients may need radiation therapy, it is important to investigate the influence of ionizing radiation on cochlear implant function. METHODS: This study tested the function of four CLARION 1.2 implants (Advanced Bionics, Sylmar, CA, U.S.A.) after varying radiation treatments with gamma rays. The first implant received a cumulative dosage of 69 Gy over nine treatments (single doses between 0.1-30 Gy). The second was irradiated with a total of 90 Gy, receiving three treatments of 30 Gy each. The third and fourth received doses more typical of patient therapy (i.e., 2 Gy) approximately 30 times, for a cumulative dosage of approximately 60 Gy. Implant function was tested after every treatment; the CLARION implant incorporates a back-telemetry system, allowing impedance and current output testing. RESULTS: Despite the type of treatment, the results were quite consistent: difficulties in function occurred when the cumulative dosage inside the implant was approximately 60 Gy. The first implant recovered completely and the second recovered partially. DISCUSSION: The CLARION 1.2 cochlear implant seems to safely withstand approximately 60 Gy of radiation before experiencing functional difficulties. In a clinical situation, the implant would not likely be in the target volume irradiated, and thus the patient's therapeutic cumulative dosage might be higher.     

Corrosion induced failure of a stainless steel orthopaedic implant device

Failure investigation was carried out for the fractured orthopaedic implant device (Sherman bone plate) which fractured in the ulna of the right hand of a patient. Marked macroscopic beach marks were radiating from the pit present in the inner side of the countersunk hole. Fatigue striations, microcracks and pitting attack were noticed in the fractured site of the implant. Electrochemical potentiokinetic reactivation test on failed implant showed a significant reactivation peak indicating the presence of chromium-depleted regions. The failure of the Sherman bone plate was the consequence of corrosion fatigue due to the propagation of cracks radiating from the pit present in the crevice. The crack propagation was aggravated by the biomechanical force exerted on the implant.     

Generation, Microwave Spectrum, and Ab Initio MO Calculation of trans-1-Nitrosopropene, CH3CH&dbond;CH-NO (syn form)

With the increasing worldwide spread of the Isshiki technique for external vocal fold medialization, some disadvantages and limitations have also emerged. and an increasing demand for a ready-made and standardized implant system can be observed. For this reason. I started experimental and clinical investigations with the goal of replacing the silicone with a safer material, and also simplifying and standardizing the surgical procedure. In particular, the danger of implant dislocation should be excluded with greater certainty. As a result, I have developed an implant made of medical-grade titanium. My surgical experiences in 20 patients with this newly developed titanium vocal fold medializing implant revealed that vocal fold medialization could be performed easily and that no perioperative complications occurred in any case. The major advantage was a significant reduction of operative time due to the preformed implant. This is not only more convenient for both the surgeon and the patient, but is also critical for obtaining optimal results due to the reduced intralaryngeal swelling and hematoma. The reduction of the glottic gap by the operation was statistically significant. Significant improvement of all voice parameters was achieved and demonstrated by a statistically significant reduction of the voice dysfunction index. Compared to the current techniques and implant systems, I see the following additional advantages: 1) titanium is a relatively safe implant material with excellent biocompatibility: 2) the design of the implant ensures optimal fixation and stabilization: 3) the implantation technique and handling is simple and time-saving; 4) the titanium sheet is easy to shape and adapt to the individual situation: and 5) only 2 sizes of implants, and no expensive instruments, are required.     

The epidemiology, clinical characteristics, and natural history of older nursing home residents with a diagnosis of Parkinson''s disease

This study investigated the occlusal stress distribution to the implant and soft tissue for the implant-retained overdenture. The stress at the molar residual ridge and the strain around the implant were measured on an experimental resin cast using static and dynamic loading. The influence of connecting structures of stud attachments on stress distribution was discussed. The occlusal stress had a tendency to concentrate on the implant, especially in the areas distal to the implant. The modified magnetic attachment system, using a silicone-covered magnet, provided the optimal stress distribution.     

Immediate implant surgery: three-year retrospective evaluation of 50 consecutive cases

Since August 1989, 35 consecutive patients were treated with immediate implants to replace 50 teeth requiring extractions as a result of root fractures, endodontic instability, nonrestorable carious lesions, or periodontal disease. Defects relative to the implant were morphologically grouped and were treated for bone regeneration with demineralized freeze-dried crushed cancellous bone (DFDBA), e-PTFE membrane, or both. Thread exposure initially ranged from 4 to 20 threads, while implant lengths varied from 8.5 to 18 mm. The mean implant length was 15 mm, with mean thread exposure of 11.34 threads, or 54% of the threaded length of the implant. Reentry confirmed 100% thread coverage in all but one implant in the no-wall group treated with DFDBA alone. Histologic evaluation of three cases confirmed viability of the regenerated bone. The patients were followed through April 1993, with 49 implants (98%) remaining osseointegrated and functional, supporting the predictability of immediate implant placement. The age of the patients ranged from 16 to 80 years, hence implant placement considerations relative to adolescents are also discussed.     

Lacrimal obstruction after migration of orbital floor implant

A 7-year-old girl developed epiphora, recurrent purulent conjunctivitis, and dacryocystitis 32 months after the repair of a traumatic orbital floor fracture. Dacryocystography and surgical exploration revealed that migration of the orbital floor implant had caused obstruction of the nasolacrimal duct at the sac. Migration of the implant was probably due to a failure to anchor the implant properly to bone.     

Inhibition of eFGF expression in Xenopus embryos by antisense mRNA

This pilot study analyzed the bone reactions to early loaded titanium plasma-sprayed implants. A total of 24 titanium plasma-sprayed implants (12 in the maxilla and 12 in the mandible) (Primary Healing Implant, Legnano) were inserted into four Macaca fascicularis monkeys with instruments specially designed to obtain a precise fit of the implant in the bone socket. A metal superstructure was cemented into 10 mandibular and 10 maxillary implants 15 days after implant insertion. The four remaining implants were used as controls. Eight months after implant placement, a block section was carried out, the defect was filled with nonresorbable hydroxyapatite, and all 24 implants were retrieved. The implants were treated to obtain thin ground sections that were examined under normal and polarized light. Histologic analysis showed that bone was observed around the implant surface in all implants. Morphometric analysis demonstrated that bone lined 67.2% (SD = 3.1%) of the maxillary implant surface, and 80.71% (SD = 4.6%) of the mandibular implant surface. No differences were found in the percentage of bone-implant contact in the control implants. In the loaded implants, however, the bone around the implants had a more compact appearance. The study demonstrated that it is possible to obtain a high percentage of bone-implant contact in early loaded titanium plasma-sprayed implants.     

Identification and characterization of a new splicing variant of vascular endothelial growth factor: VEGF183

The purpose of this study was to determine implant survival rates by means of life table analyses for a cohort of patients not part of a prospective efficacy trial and treated by practitioners at varying experience levels. Prognostic variables associated with implant failure were identified by means of proportional hazards models and advanced statistical methods that account for patient effects. Ninety-nine consecutive patients treated from 1987 to 1991 with follow-up to 1994 were included in this retrospective study. A total of 384 dental implants (79.7% Br?nemark, 19.3% IMZ plasma-sprayed, 1% IMZ hydroxyapatite-coated) were placed and subsequently supported 108 prostheses. Survival and proportional hazards modeling were used to generate Kaplan-Meier survival curves and to identify variables associated with implant failure. Survey data analysis was used to adjust for any patient effects for variables identified as significant through the proportional hazards models. Thirty-four implants failed over the follow-up period (median follow-up time 3.6 years), resulting in an overall failure rate of 8.9%. Seventeen of 99 patients experienced an implant failure. When prosthesis type was excluded from the modeling process, survey data analysis identified posterior location and an implant width of less than 4.0 mm as being associated with implant failure (all P < .05).     

Morphology of the bone that supports endosteal dental implants. Transmission electron microscopic and high voltage electron microscopic observations

The morphologic features of the bone-dental implant interface were investigated using an in vivo dog model. The undecalcified bone and associated support tissues were serially sectioned and examined with both conventional and high voltage transmission electron microscopy. A varied morphologic appearance of the tissues supporting clinically and radiographically appearing integrated implants was observed. Osteoblasts were observed at the implant interface, and osteocytes were routinely seen encased within lacunae extremely close to the implant surface. Often these osteocytes extended cellular projections to the implant surface. The variable tissue types observed were suggestive of healthy lamellar and appositional type mineralization patterns adjacent to the implants.     

Resonance frequency analysis: measuring implant stability and osseointegration

Achievement and maintenance of implant stability are prerequisites for long-term positive outcomes for osseointegrated implants. Thus, implant stability is the key to clinical success. Until recently, it was not possible for the clinician to predictably distinguish implants with different degrees of stability. Because there seems to be a correlation between implant failure and bone properties, it is possible that clinically firms implants with poor stability are more prone to failure than more stable implants. This article discusses the development and possible future use of a novel technique for clinical measurement of implant stability and osseointegration--resonance frequency analysis.     

Urinary free deoxypyridinoline levels during childhood

The purpose of our study was to determine serial mineral density changes in coralline hydroxyapatite orbital implants after implantation into the human socket. Prospective analysis by quantitative computed tomography determined the mineral density of hydroxyapatite orbital implants in five patients before and at two time intervals after implantation. Mineral density of the spheres increased an average of 135% after implantation (3-8 months) from preoperative measurements. The density continued to rise an average of 5% (range, -9%-16%) at the second postoperative period (22-39 months). Average follow-up was 30 months. The increased density in the nonevisceration patients was noted in the regions of the scleral windows and the exposed posterior implant where the cornea had been removed from the scleral wrap. The mineral density of hydroxyapatite spheres markedly increases after implantation. Approximately 2 to 3 years later, the densities continue to increase slightly in enucleation and secondary implant cases. An evisceration implant was the only implant to lose density. This study shows no decrease in the mineral density of orbital coralline hydroxyapatite enucleation implants, suggesting a lack of implant mineral resorption.     

Histological evaluation of bone reactions to aluminium oxide dental implants in man: a case report

Alumina implants have been shown to possess high biocompatibility. The authors present the case of an aluminium oxide ceramic implant removed because of fracture of the abutment after a 30-month loading period. It was possible to observe microscopically that the implant was covered by highly mineralized mature compact lamellar bone; no connective tissue or inflammatory cells were present at the interface. Osteocytes were observed very close to the bone-implant interface. These features indicate the good biocompatibility of the implant.