One clinical visit for a multiple implant restoration master cast fabrication

The making of a one-piece, long-span, implant-supported prosthesis with conventional procedures frequently has difficulties associated with the accuracy of fit. This article presents a clinical and laboratory procedure for making an accurate implant working cast that facilitates fabrication of the casting on the master cast. The procedure demonstrates the process of sectioning and rejoining of the resin between the transfer copings and then pouring the impression by first joining the analogs alone with impression plaster, sectioning it, and rejoining it again to stabilize the analogs, and finally, using dental stone to pour the impression. Clinical, radiographic, and laboratory (optical microscope) measurements for one clinical implant restoration confirm the accuracy of fit of this one prosthesis made with this procedure. Its advantage is that it can allow fabrication of the final casting on the cast, thereby eliminating the clinical time necessary to obtain repetitive solder indexes, and thus minimizing inconvenience to the patient. (J Prosthet Dent 1997;78:550-3.)     

Surface Quality and Long-term Dimensional Stability of Current Elastomeric Impression Materials after Disinfection

PURPOSE: The objectives of this investigation were to evaluate the effect of disinfection on surface quality and dimensional stability of more recent, reformulated vinylpolysiloxane (VPS) and polyether (PE) materials. METHODS: Using ANSI/American Dental Association (ADA) specification 19 protocols, 50 impressions of stainless steel dies were made with each material. Ten impressions of each material were randomly assigned to a treatment group: (1) no disinfectant; (2) 10-minute dual phenol immersion; (3) 1-hour dual phenol; (4) 10-minute sodium hypochlorite (NaOCl); and (5) 1-hour NaOCl. Impression surface quality immediately after disinfection was categorized as smooth/shiny, matte, or wrinkled/sticky. Dimensional stability was evaluated by measuring dimensional accuracy according to specification 19 after 24-hour, 1-week, and 2-week storage at ambient laboratory conditions. RESULTS: The PE material surface quality was significantly affected (Pearson Chi-square, p相似文献   

A look at allied dental education in the United States

BACKGROUND: The American Dental Association conducts surveys of educational programs in dental assisting, dental hygiene and dental laboratory technology. The 2002-2003 survey included questions about enrollment, graduates, program information and trends. METHODS: The ADA Survey Center mailed the Survey of Allied Dental Education to 548 program directors of dental assisting, dental hygiene and dental laboratory technology educational programs. They also sent several follow-up notices as a reminder to complete the survey. A 100 percent response rate is mandatory for continued accreditation by the Commission on Dental Accreditation. Association staff members resolved inconsistencies in the data and analyzed them before producing a final report. RESULTS: The number of applications to, first-year enrollment in and number of graduates in dental hygiene and dental assisting educational programs have increased during the last five years. During the same period, the number of applications to, and graduates of, dental laboratory technology educational programs decreased, but first-year enrollment increased slightly. CONCLUSIONS: Results from these surveys help address the concerns of the public and the profession regarding allied dental manpower levels. They also provide information for those interested in applying to individual allied dental educational programs. PRACTICE IMPLICATIONS: Private dental practices employ the majority of graduates of allied dental educational programs. Recent graduates of dental assisting and hygiene programs continue to supply the office staff members needed to support the delivery of dental care.     

Comparison of Dentists'' Treatment and Management of Normal and Handicapped Patients

Forty-eight of 120 dentists (40%) responded to a survey using a two-questionnaire time-series design. Responding dentists with a median age of 36 years and 9.5 years in practice had received education in care of the handicapped mainly in dental school (42%) and continuing education (40%). They were asked to make the same treatment and practice management decisions for both normal and handicapped patients. No significant differences were found between normal and handicapped patients in the amount of time dentists spend on diagnosis, treatment, planning, or recall (p less than 0.05). For both normal and handicapped patients, the dentists as a group always chose the same option as treatment of choice for both normal and handicapped patients most frequently from a list of treatment or management options. Individual dentist consistency between normal and handicapped patients in treatment and management was good, with four out of five dentists choosing the same first treatment of choice for both normal and handicapped patients for similar circumstances. Only about one out of six dentists maintained a consistent priority sequence for both normal and handicapped patients when asked to rank a list of four or five possible treatment or management choices.     

A comparative analysis of the accuracy of implant transfer techniques

Four different implant transfer techniques using two master cast systems (solid cast and Zeiser system) were evaluated and compared with respect to the accuracy with which abutment positions were reproduced. A stainless steel experimental analogue with two anterior and two posterior fixtures and abutments was fabricated. Polyether impressions (14 each) were made by use of four techniques, (I) nonsplinted, (II) splinted with dental floss and acrylic resin, (III) splinted with orthodontic wire and acrylic resin, and (IV) splinted with acrylic resin alone. The fourteen impressions of each technique were divided into two equal groups: group 1, solid cast system, and group 2, Zeiser system. The abutments of each master cast were measured vertically and horizontally with a profile projector. Statistical analysis indicated no significant difference between the splinted and nonsplinted techniques. The Zeiser system provided more accurate interabutment relationships for the posterior region than the solid cast system.     

An object-relational model for structured representation of medical knowledge

Domain specific knowledge is often not static but continuously evolving. This is especially true for the medical domain. Furthermore, the lack of standardized structures for presenting knowledge makes it difficult or often impossible to assess new knowledge in the context of existing knowledge. Possibilities to compare knowledge easily and directly are often not given. It is therefore of utmost importance to create a model that allows for comparability, consistency and quality assurance of medical knowledge in specific work situations. For this purpose, we have designed on object-relational model based on structured knowledge elements that are dynamically reusable by different multi-media-based tools for case-based documentation, disease course simulation, and decision support. With this model, high-level components, such as patient case reports or simulations of the course of a disease, and low-level components (e.g., diagnoses, symptoms or treatments) as well as the relationships between these components are modeled. The resulting schema has been implemented in AMOS II, on object-relational multi-database system supporting different views with regard to search and analysis depending on different work situations.     

Pathological mandibular fractures following third molar removal

Seventeen patients, who presented mandibular fractures following third molar removal, were treated in the Department of Oral and Maxillofacial Surgery at the University Hospital Freiburg between 2000 and 2004. Clinical and radiological data were analysed to evaluate the possible risk of fracture following third molar removal. Our data show an increased rate of pathological mandibular fractures in males over 40 years of age, following removal of a difficult lower wisdom tooth with a high retention grade that necessitated bone removal. Fourteen out of 17 fractures occurred postoperatively. In six cases, no fracture was visible in radiographs during the primary investigation. Pathological mandibular fractures were typically located anterior to the mandibular angle (n=15). We recommend informing patients about possible risks and, in selective cases, a soft diet for up to 4 weeks after the operation. A cracking noise reported by the patient is the most important indication of a fracture. If, initially, the fracture is radiologically undetectable, we recommend the use of radiological controls.     

Copper-zinc superoxide dismutase activity in normal and inflamed human dental pulp tissue.

Information regarding the presence of the free radical scavenging (inactivating, dismutating) enzyme superoxide dismutase in human dental pulp was sought. Free radicals, such as the superoxide anion radical (O2-) and the hydroxyl anion radical (OH.), are powerful biological oxidants produced by phagocytes during the normal tissue response to injury and infection. Also produced is hydrogen peroxide (H2O2), an aggressive oxygen species formed by the reaction of superoxide with itself, i.e., a dismutation in which one molecule of O2- is oxidized by the other. These three reactive oxygen intermediates serve as part of the normal host biological defense mechanism for the inactivation of microorganisms and the breakdown of their toxic products. Both normal and inflamed dental pulps were assayed for the presence of this enzyme. Superoxide dismutase activity was identified in the normal pulpal tissues. There was a slight decrease in activity with age. In the inflamed pulpal tissues, enzyme activity was markedly and significantly increased in comparison to that in the normal tissues. These observations indicate that human dental pulp possesses an endogenous defense mechanism designed to protect the tissue components (cells and matrix) from the toxic effects of the reactive oxygen intermediates. In this regard, the inflammatory response of this specialized and somewhat isolated (compartmentalized) tissue is not unlike that seen in other connective tissues.