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Biomedical subjects

D E Steflik

Publications and source records attributed to D E Steflik.

At least 37 records · Page 2Linked to original sources
PubMed1994

Evaluation of the effects of diagnostic radiation on titanium dental implant osseointegration in the micropig.

The effect that diagnostic radiation may have on peri-implant supporting alveolar tissues is not well understood. Fifty-four (54) titanium dental implants were inserted into the posterior mandible of nine micropigs. At implant placement surgery, 18 implants were exposed to either 2 (diagnostic) or 10 (excessive) doses of diagnostic radiation; the remaining 36 implants served as controls. Fourteen weeks after implant placement, standardized clinical radiographs were taken, pigs were euthanized, and implants with supporting alveolar tissues were prepared and examined by light and scanning electron microscopy (SEM). Ninety-seven sections were evaluated by SEM for morphometric and morphologic analyses. The mean percent of implant length in contact with bone was 47% for the controls and 53% for the implants receiving radiation. Five implants were lost during the initial healing phase and four implants were clinically mobile at time of euthanasia, giving a success rate of 83% (45/54). Correlative light microscopy of peri-implant supporting tissues revealed no distinct differences between the microvasculature of controls versus implants exposed to radiation. Standardized clinical radiographs revealed crestal saucerization in both control and radiated implants. This study revealed no statistically significant difference for the percent of implant length in contact with alveolar bone for controls or implants exposed to 2 or 10 doses of diagnostic radiation at implant placement time.

Alveolar Process↗
PubMed1994

Light microscopic and scanning electron microscopic analyses of dental implants retrieved from humans.

This paper reports analyses obtained from 51 implant cases retrieved from humans and submitted to the AAIDRF-MCG Implant Retrieval Center. The undecalcified samples were embedded in PMMA and examined with scanning electron microscopy and with routine light or Nomarski microscopy. Cases included individual implants as well as 2 mandibles obtained at autopsy. Retrieved implants were sometimes shown to be encapsulated with connective tissue (CT), whereas other implants were apposed by bone, with only minimal CT association. In the latter cases, the implants were apposed by substantial amounts of viable bone. Nomarski microscopy disclosed the orientation and close apposition of the collagen bundles comprising the interfacial bone. In these cases where close bone apposition was observed to the implants, implant fracture was often the cause of failure. Periodontal lesions were reported around some implants showing a marked degree of inflammatory cell infiltrate (ICI). This study underscores the need for evaluation of failed human dental implants. Failure of implants placed longer than 10 years ago (perhaps loaded immediately) may be due to loss of bone support, CT encapsulation, and ICI (i.e., biological failure). Failure of more recently placed implants could also be due to this scenario, but failure was more often ascribed to biomaterial failure.

Alveolar Process↗
PubMed1993

Osteogenesis at the dental implant interface: high-voltage electron microscopic and conventional transmission electron microscopic observations.

The osteogenesis of mandibular bone to endosteal dental implants was examined using an in vivo dog model. One half of the implants examined were unloaded implants, with the remaining one half prosthodontically loaded for 6 months. Undecalcified mandibular implant samples were examined with both high-voltage electron microscopy (HVEM) stereology and routine transmission electron microscopy. The osseous interface to integrated implants was shown to vary in its morphology. Mineralized bone was observed directly apposing the implant, often separated from the implant by an electron-dense deposit of approximately 50 nm. Within this densely mineralized matrix, osteocytes were routinely observed. Adjacent areas were shown to contain slightly wider zones of either a less dense mineralized matrix or, alternatively, unmineralized tissue. Other zones consisted of wider unmineralized matrices containing collagen fibers and osteoblasts. These latter zones were consistent with the appearance of an appositional type of bone growth. Because bone is a dynamic, actively remodeling tissue, a varied morphology of the support tissues to dental implant is not unexpected. Areas of mature bone interfacing with successfully integrated implants were demonstrated, as well as areas adjacent to the mature bone that were undergoing remodeling or mineralization. This study has also shown that HVEM stereology is a valuable research tool to investigate the oral tissue interface with dental implants.

Aluminum Oxide↗
PubMed1993

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.

Animals↗
PubMed1993

Histomorphometric and histologic observations of bone healing around immediate implants in dogs.

This paper reports histologic and histomorphometric results concerning bone healing around 13 pure titanium screw-shaped root-form implants that were placed in three mongrel dogs immediately after extraction of maxillary and mandibular premolars. Osseous healing around the implants showed a great deal of variability depending on the arch in which the implant was placed and on the original anatomy of the implant site. Implants placed in the mandible showed the greatest amount of bone apposition, with a mean total bone of 60.3%. Implants placed in the maxilla showed less bone and greater variability both visually and statistically, with a mean total bone of 46.3%. The values obtained for bone after 5 months of healing of the control sites were consistent with the values obtained for bone approximating the implants after the same time period. This was true for both arches. It was impossible to visually or statistically discriminate between sham surgical control sites and routine control sites or between implant sites and either of the control sites. Implant surgical procedures and implant placement seemed to have little effect on the tabulated values beyond tooth extraction alone. This research suggests that immediate implants have the potential for developing good bone apposition depending on the area of implantation.

Alveolar Process↗
PubMed1993

Clinical evaluation data from a comparative dental implant investigation in dogs.

This report presents one-year clinical evaluation data from 120 ceramic and titanium cylindrical and titanium blade-type implants placed in the mandibles of 30 adult dogs. Ninety-six of the implants supported fixed bridges. The bone and gingival health was evaluated by the following indices: crevicular fluid volume index; gingival bleeding index; plaque accumulation index; clinical mobility index; and a quantitative mobility index utilizing the Periotest instrument. Results from this investigation suggest that, overall, the ceramic implants exhibited more fractures and had more mobile implants than did the titanium implant systems. Overall, complete one-year clinical evaluation data demonstrate healthy tissue responses to 112 of the 120 implants. Further, the Periotest instrument appears to offer a more quantitative assessment of clinical mobility. Also, it appears that the clinical evaluation protocol utilized in this study is a valid procedure to use for the assessment of clinical serviceability.

Analysis of Variance↗
PubMed1993

Experimental studies of the implant-tissue interface.

This comparative study analyzed the epithelial, gingival connective tissue, and osseous tissue interface with clinically and radiographically integrated endosteal dental implants. Undecalcified interfacial tissues were sectioned for both routine transmission electron microscopy (TEM) and for High Voltage Electron Microscopy (HVEM). A protective perimucosal biological seal was formed by regenerating soft tissues (epithelium and connective tissue). Inferior to this protective soft-tissue attachment seal, the apical support complex was shown to vary in morphology. Mineralized bone was closely apposed to significant regions of the implants, separated only by an electron-dense deposit of approximately 20 nm. Osteoblasts were observed adjacent to the implant, as were osteocytes within the underlying supporting bone. Osteoblasts were observed associated with a connective tissue stroma adjacent to the existent mineralized bone. Osteocyte cellular processes extended toward adjacent osteocytes, toward vascular elements, and directly to the implant surface. These observations demonstrate the healthy interface of mineralized tissues with both root-form and blade implants. Mineralization patterns of the bone supporting the implants appeared consistent with normal mandibular maturation patterns.

Alveolar Process↗
PubMed1992

High-voltage electron microscopy and conventional transmission electron microscopy of the interface zone between bone and endosteal dental implants.

The interface between mandibular bone and endosteal dental implants was examined with an in vivo dog model. Undecalcified mandibular implant samples were observed with both conventional transmission electron microscopy and high-voltage transmission electron microscopy (HVEM). Results demonstrated the variable nature of the interfacial support tissues. Mineralized bone was often found within 50 nm of the implant surface, separated from that surface only by an electron dense deposit. Osteocytes were observed close to the interface encased within lacunae extending numerous cellular processes through canaliculi. An osteoblast was also observed directly at the interface within a developing lacuna. Other interfacial areas exhibited a finely fibrillar and more electron lucent morphology. Furthermore, other areas were shown to be composed of wider zones of extracellular products containing collagen fibrils, ground substance, and calcified inclusions. Because bone is an actively growing and remodeling tissue, these different morphological zones around the entire area of the implants would appear to confirm the dynamic tissue response to endosteal dental implants. Further, HVEM stereology was shown to be an exciting research tool to investigate this tissue response.

Animals↗
PubMed1992

Comparative implant research in dogs: a prosthodontic model.

One-hundred twenty endosteal dental implants were inserted bilaterally in the mandibles of 30 adult mongrel dogs after bilateral extraction of all premolars. The 120 implants were evenly divided into one- and two-stage systems and included ceramic and titanium cylindrical root-form implants and titanium blade implants. The research design of this investigation divided the 30 animals into 10 groups of three dogs. This article describes an animal model that is useful in evaluating dental implant designs and compares the results with those from humans. In particular, this article delineates the prosthodontic approach appropriate for this model using one- and two-stage titanium implants. Rexillium alloy fixed prostheses were placed on 32 endosteal implants and 16 natural mandibular molar teeth. The implants and prosthetic components of the Sterio-Oss implant system were used. All prostheses are functional with minimal maintenance. To date, after 1-year of follow-up, none of the implants have been lost and none of the fixed prostheses have required recementation or maintenance other than normal hygiene. Histologic and survival data as well as results with other implant systems will be presented in other reports.

Animals↗
PubMed1992

A light and electron microscopic comparison of osseointegration of six implant types.

This study compared six commercially available implants placed in an animal model for 5 months. Twelve of the implants were used for light microscopic analysis, and the remaining 12 were used for scanning electron microscopic analysis. With the exception of one implant, newly formed bone was evident in direct apposition to portions of all control implants. The light microscopic and scanning electron microscopic evaluations of the tissues surrounding the six commercially available implant types indicated that initial osseointegration is likely with all types. Implant design, material, and submergibility do not appear to be essential for initial osseointegration to occur as long as a biocompatible material is selected and the implant is placed using minimally traumatic surgical techniques.

Aluminum Oxide↗
PubMed1992

Transmission electron microscopic and high voltage electron microscopic observations of the bone and osteocyte activity adjacent to unloaded dental implants placed in dogs.

The purpose of this report is to describe ultrastructural observations of the bone and associated tissues supporting 24 unloaded endosteal dental implants placed in mongrel dogs (canis familiaris). The following 3 specific areas of the supporting tissues were targeted: 1) the osteocyte populations; 2) the mineralized collagen fiber matrix of the bone; and 3) an electron dense interfacial deposit. To investigate these areas, transmission electron microscopy and high voltage electron microscopic (HVEM) protocols were emphasized. HVEM permitted stereologic observations. Further, all observations were obtained from undecalcified tissues obtained from animals with commercially available implants placed into the mandible. From the study we observed a mineralization pattern of the implant supporting bone that was similar to those events occurring naturally within the mandibular bone. Osteocyte morphology was similar whether the osteocytes were found well below the implant interface or close to the interface. Osteocytes within lacunae were routinely found close to the implant interface, often extending cellular processes through canaliculi to the bone-implant interface. At the interface, an electron dense deposit approximately 50 nm in thickness was often observed. In interfacial regions, densely mineralized collagen fibers were observed running primarily parallel to the implant surface. This dense mineralized tissue was separated from the interface by a mineralized, but finely fibrillar matrix of approximately 200 nm in thickness.

Animals↗
PubMed1992

Simulated implant surgery in rabbit long bones: a descriptive study.

The objectives of this study were: (a) to observe and describe the variability of bone healing in implant receptor sites which were prepared in rabbit femurs by use of different surgical methods; and (b) to determine if the animal model which was used was suitable for the detection of differences in healing reactions in implant receptor sites which were prepared by different surgical methods. Three 3-mm-wide implant receptor sites were prepared in the right and left femurs of four large New Zealand white rabbits. The surgical parameters used in preparation of the different sites included: low speed with no irrigation (LSO); low speed with internal irrigation only (LSI); low speed with external irrigation only (LSE); high speed with no irrigation (HSO); or high speed with external irrigation only (HSE). The sites were randomized so that each animal had one of each type of site in either the right or left femur. A non-treated control site was located in each animal for comparison with experimental sites. The animals were killed at 7, 14, 21, and 28 days post-operatively. The resultant samples were fixed, embedded, sectioned, and stained with basic fuchsin and toluidine blue. The results indicated that this was probably not a suitable animal model, since no discernible differences were detected in the various healed sites.

Animals↗
PubMed1992

Electron microscopy of bone response to titanium cylindrical screw-type endosseous dental implants.

This study investigated the undecalcified bone and enveloping tissues supporting commercially pure titanium one-stage and two-stage endosseous dental implants placed into the mandibles of adult mongrel dogs. Correlative light microscopy, transmission electron microscopy, and high-voltage transmission electron microscopy demonstrated a dynamic bone interface to the implants. Mineralized tissue was routinely observed within 20 to 50 nm from the implant interface, separated from the implant interface only by an electron-dense deposit. The densely mineralized collagen fiber matrix was oriented parallel to the implant interface, as were osteocytes that were found close to the interface. Osteocytic projections progressed through canaliculi, often directly to the implant interface. Unmineralized areas that appeared to have the potential for mineralization were also identified.

Alveolar Process↗
PubMed1992

Comparative implant research in dogs: prosthodontic protocol using two-stage ceramic endosseous dental implants.

This report describes one phase of a long-term comparative implant investigation involving 20 of 120 endosseous implants placed in 30 adult mongrel dogs. Fixed prostheses involving 16 of the 20 (4 control implants) two-stage ceramic endosseous implants have been provided using routine prosthodontic procedures and the limited prosthetic components available for the Bioceram Series II implant system. The prostheses have proven to be functional with minimal maintenance. To date, after 1 year of follow-up, 2 of the two-stage implants have exhibited problems caused by fracture of the hexagonal collar. None of the implants to date has been lost and none of the fixed prostheses has required re-cementation or any other type of maintenance other than normal hygiene. Clinical evaluation suggests continued implant and prosthesis serviceability after 1 year in function.

Aluminum Oxide↗
PubMed1991

Long-term memory of acute postsurgical pain.

The long-term memory of acute postoperative pain intensity was evaluated in a population of patients who had undergone the removal of impacted third molar teeth. The results suggest a positive correlation between experienced and remembered intensities of postsurgical pain for up to 3 years after surgery. They also suggest that males and females do not differ significantly in their reports of postsurgical pain intensity, nor do they differ significantly in their memories of pain intensity. Pain recall using verbal pain descriptors was more reliable than recall with visual analog scales. Patient reports of intensity of past postsurgical acute pain, particularly those reports obtained with verbal descriptors, may be useful in the planning of treatment and in the selection and evaluation of analgesic regimens.

Adult↗
PubMed1991

Dental implants retrieved from humans: a diagnostic light microscopic review of the findings in seven cases of failure.

With the increased use of dental implant systems, an increase in the number of implants removed from patients has also been observed. This investigation attempted to elucidate some underlying causal determinants of implant failure employing light microscopic analyses. Valuable data can be obtained from implants retrieved from patients. Implant success is predicted on proper patient selection and treatment planning, careful surgical procedures, careful prosthodontic management, and continued oral hygiene maintenance.

Aged↗