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Biomedical subjects

A L Sisk

Publications and source records attributed to A L Sisk.

At least 19 recordsLinked to original sources
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

Correlative transmission electron microscopic and scanning electron microscopic observations of the tissues supporting endosteal blade implants.

Correlated scanning electron microscopic (SEM), routine transmission electron microscopic (TEM), and high-voltage transmission electron microscopic (HVEM) observations demonstrated that one-stage and two-stage endosteal blade-type implants were well-supported by mandibular tissues after five months of unloaded healing in dogs. Areas of the implants were apposed directly by mineralized tissues without any apparent interposed unmineralized connective tissue. Other areas of the implants were apposed by narrow areas of unmineralized tissue, often containing osteoblasts. These unmineralized areas were interposed between the implant and a supporting mineralized matrix. A healthy mix of tissues, which represented a dynamic osseous complex, supported these serviceable blade-type dental implants. This study, for the first time in the dental implant literature, utilizes HVEM stereology for evaluation of the bone-implant interface.

Alveolar Process↗
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↗
PubMed1992

Long-acting local anesthetics in dentistry.

Long-acting local anesthetics have proved to be effective for the suppression of both intraoperative and postoperative pain. They are useful for lengthy dental treatments and for prevention of severe pain following many types of surgical procedures. Although the currently available long-acting local anesthetics for dentistry have minimal side effects in the doses usually employed, there are potential problems. Bupivacaine, for example, can cause significant cardiac depressant and dysrhythmogenic responses. Etidocaine has less pronounced effects on the cardiovascular system, but its use may be associated with inadequate control of intraoperative bleeding. A new long-acting local anesthetic, ropivacaine, appears to offer advantages over either of the currently used long-acting agents.

Amides↗
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↗
PubMed1990

When a patient with a bleeding disorder needs dental work. How you can work with the dentist to prevent a crisis.

Patients with bleeding disorders need close cooperation between their physician and their dental practitioner to receive safe, comprehensive dental care. When indicated, physicians must advise a compromised treatment plan to avoid deep injections or surgical procedures that may initiate a bleeding crisis in patients at risk. The conditions most commonly seen that require special consideration are long-term use of antithrombotic agents, platelet dysfunction caused by chronic renal failure, and congenital clotting factor deficiencies. Even these patients may undergo a high-risk procedure, such as periodontal surgery, with adequate precautions and preparation.

Blood Coagulation Disorders↗
PubMed1990

A comparison of preoperative and postoperative naproxen sodium for suppression of postoperative pain.

Using a within-subject, crossover experimental design, this study compared the efficacies of a nonsteroidal anti-inflammatory drug, naproxen sodium, 550 mg, administered either 30 minutes preoperatively or 30 minutes postoperatively to 36 patients undergoing the removal of impacted third molar teeth. Pain intensity was assessed postoperatively for 8 hours. Treatment with naproxen sodium, 550 mg, 30 minutes following completion of surgery was just as effective as presurgical administration in controlling postoperative pain. Administration of naproxen sodium in the immediate postoperative period may be indicated for optimum postoperative analgesia for patients in whom preoperative oral intake is contraindicated.

Adolescent↗
PubMed1990

Scanning electron microscopic studies of the oral tissue responses to dental implants.

Scanning electron microscopy (SEM) and its associated technologies have proven invaluable in elucidating the interfacial oral tissue responses to dental implants. Since the dental implant must extend from the mandibular or maxillary jaw, through the oral mucosa, and into the oral cavity, these tissue responses include epithelium, connective tissue and bone. The continual occlusal forces acting upon these tissues reinforce the dynamic character of these tissue responses. Immediately upon implantation, a healing phase begins as a response to the implanted biomaterial. Following this immediate response a longer healing phase occurs, beginning approximately 1 week after implantation, resulting in the modeling of bone to the implant as well as the formation of epithelial attachment to the implant. This later, delayed healing continues throughout the lifetime of the implant since these tissues must die and be replaced by similar tissues. Current dental research employing scanning electron microscopy is now documenting these tissue responses. This paper reviews, in detail, SEM observations of these tissue responses.

Animals↗
PubMed1990

Ultrastructural investigations of the bone and fibrous connective tissue interface with endosteal dental implants.

The interface between the tissues of the oral cavity and ceramic and titanium cylindrical endosteal dental implants was investigated with correlated light microscopy, transmission electron microscopy and scanning electron microscopy. This study suggested that mandibular bone can directly interface and form an intimate association with one-stage endosteal dental implants. This potential attachment matrix is composed of a composite of calcified bone, and an osteoid unmineralized matrix in association with an apparent osteogenic connective tissue. Further, results from this study suggested that at a level inferior to the junctional epithelium, and superior to the level of crestal bone, fibrous connective tissue can attach to the dental implant. This non-loadbearing attachment of gingival connective tissue could, by contact inhibition, prevent apical epithelial migration. In association with previously documented epithelial attachment, such apical support and connective tissue attachment appears to suggest that endosteal dental implants can be adequately maintained in the oral cavity.

Animals↗
PubMed1989

Comparison of preoperative and postoperative diflunisal for suppression of postoperative pain.

Despite the demonstrated therapeutic advantage of preoperatively administered nonsteroidal anti-inflammatory agents (NSAIAs) in suppressing postoperative pain, clinicians are reluctant to administer these drugs orally before surgical procedures performed using sedation or general anesthesia. Using a within-subject, crossover experimental design, this study compared the analgesic efficacies of an NSAIA, diflunisal 1,000 mg, administered either 30 minutes preoperatively or 30 minutes postoperatively to 20 patients undergoing the removal of impacted third molars. Pain intensity was assessed preoperatively and postoperatively for eight hours using category-rating and visual analog scales. Treatment with diflunisal 30 minutes after completion of surgery proved to be just as effective in suppressing postsurgical pain as presurgical administration. Administration of an NSAID in the immediate postoperative period may be indicated for optimum postoperative analgesia for patients in whom preoperative oral intake is contraindicated.

Adolescent↗