Search PubMed⌕ Search

Biomedical subjects

T M Speidel

Publications and source records attributed to T M Speidel.

At least 19 recordsLinked to original sources
PubMed2001

Shear bond strength of stainless steel orthodontic brackets with a moisture-insensitive primer.

The purposes of this study were (1) to evaluate the shear bond strength of stainless steel orthodontic brackets bonded to dry and wet (with water and saliva) etched enamel with the use of the moisture-insensitive primer (MIP; Transbond; 3M Unitek, Monrovia, Calif) and (2) to evaluate the effectiveness of MIP with chemically activated (Concise; 3M Dental Products, St Paul, Minn) and light-activated (Transbond XT; 3M Unitek) resin. One hundred forty-four freshly extracted bovine teeth were divided into 12 groups (n = 12 teeth), and brackets were bonded with either of the 2 resins in combination with the conventional primer or MIP in dry or wet enamel surface conditions. The test specimens were mounted in a screw-driven mechanical testing machine (model 4204; Instron Corp, Canton, Mass) and subjected to a crosshead speed of 0.5 mm/min. The data were analyzed by 2-way analysis of variance. MIP with Concise produced slightly higher bond strengths compared with the conventional primers under wet conditions (MIP vs conventional: saliva, P <.001; water, P =.004). However, MIP in combination with Transbond XT produced comparable bond strengths on both the dry and wet etched enamel (dry, 10.14 MPa; water, 9.69 MPa; saliva, 8.90 MPa). The results of this study suggest that MIP be used only with light-activated composite resins.

Acid Etching, Dental↗
PubMed1993

Location of the mandibular center of autorotation in maxillary impaction surgery.

Controversy exists about the location of the center of autorotation of the mandible after maxillary impaction surgery. This investigation focuses on the problems associated with locating that center of autorotation and identifies factors that can increase the probability of accurately identifying its location for predicting surgical outcomes. The reliability of the Rouleaux technique for calculating the centers of rotation is established and is shown to be acceptable, as long as the landmarks used for determining the center are properly selected, and the magnitude of the rotation required is sufficient. The location of the centers of autorotation of the mandibles after maxillary impaction surgery for 46 patients was used to investigate the errors associated with landmark selection and amounts of rotation. Although there is much variation in its location, the center does not lie within the body of the condyle but instead lies away from the condyle. Guidelines for maximizing the reliability of predicting surgical outcomes on the basis of autorotation of the mandible after maxillary impaction surgery are given.

Adult↗
PubMed1989

Enamel surface abrasion from ceramic orthodontic brackets: a special case report.

The purpose of this report is to present a dramatic case of enamel abrasion from ceramic orthodontic appliances that was discovered only after appreciation of the initial findings of a study underway at the Department of Orthodontics, University of Minnesota. An artificial oral environment used in this study to simulate mastication also is described. The potential detrimental effects of ceramic appliances on tooth contact are discussed. All aspects of any new material should be investigated before its clinical application to prevent undesired side effects.

Adult↗
PubMed1987

Comparison of three methods of profile change prediction in the adult orthodontic patient.

Potential changes in the contour of the facial profile that accompany tooth movement can be important considerations in developing an orthodontic treatment plan. The objective of this study was to compare the accuracy of three different methods of predicting horizontal soft-tissue changes. Eighty-three nongrowing, orthodontically treated patients comprised the sample. Pretreatment and posttreatment lateral cephalometric hard- and soft-tissue landmark points were digitized. A coordinate system was defined, landmark coordinates were corrected for magnification, and then hard- and soft-tissue, angular, and linear measures were calculated by computer programs developed on a DEC PDP 11/44. The accuracy of prediction of soft-tissue landmark changes was compared for three prediction methods: (1) use of ratios of means of soft-tissue changes to corresponding hard-tissue changes, (2) use of a bivariate regression equation on corresponding hard-tissue landmark changes, and (3) use of stepwise multiple regression with hard-tissue changes and initial hard- and soft-tissue facial characteristics as predictor variables. For predicting changes of four soft-tissue points, multiple regression equations were slightly more accurate than ratio of means predictions. The standard errors of the estimate ranged from 0.7 to 1.1 mm for the multiple regression predictions; these were from 0.2 to 1.4 mm lower than those obtained for ratio of means predictions. The accuracy of the bivariate regression prediction technique fell between that of the other two methods. Examination of the residuals showed that the multiple regression equations consistently underpredicted the most extreme soft-tissue facial changes.

Adolescent↗
PubMed1987

Effect of timing on long-term clinical success of alveolar cleft bone grafts.

Despite the almost universal agreement on the desirability of bone grafting in the cleft alveolar process, there are little long-term data to support preference for grafting at one time versus another. Investigation was undertaken to compare the clinical success of grafts placed at three distinct developmental stages: the "primary" group consisting of 20 rib grafts placed at less than 1 year of age; the "secondary" group consisting of 19 iliac crest grafts placed when the permanent canine was one fourth to one half formed; and the "delayed" group consisting of 18 iliac crest grafts placed after eruption of the permanent canines. Patients were a minimum of 15 years of age at time of final evaluation. Records were made a minimum of 5 years postsurgery. Biometric data and periapical x-ray films were evaluated. There was a trend for the delayed group to have a decreased incidence of successful bony bridging of the graft site compared with the other treatment groups. The primary group exhibited significantly (P less than 0.001) greater ridge height and increased bone attachment than the secondary and delayed groups. There were significantly fewer teeth lost adjacent to the cleft for the primary group compared with the secondary and delayed groups. Before orthodontic treatment, there were no significant differences among groups in incidence of anterior crossbite; posterior crossbites were seen more frequently in the secondary and delayed graft groups than in the primary group (P less than 0.001). At final evaluation, there were significantly fewer anterior and posterior crossbites in the primary group than in the secondary and delayed groups (P less than 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Treatment-induced errors in occlusion following orthognathic surgery.

Posttreatment occlusion following orthognathic surgery is often different from that predicted in the treatment plan. Differences between intended and actual occlusion may be treatment-induced occlusal errors caused by mismatches between the centers of rotation of the mandible and of the articulated models. Discrepancies in the position of the articulator center of rotation (relative to the position of the center of rotation of the patient's mandible) influence the magnitude of occlusal errors. A computer model was developed to quantify these errors. As the center of rotation of the articulated models becomes more divergent from the patient's center of rotation, the magnitude of the occlusal errors increases. This magnitude increases most rapidly along the line that is perpendicular to the line joining the patient's center of rotation and a preselected mandibular landmark (incisor tip or molar cusp, for instance). For small changes in vertical dimension, clinically insignificant errors result, independent of the degree of mismatch between the centers of rotation. Clinical implications of these findings are discussed.

Computers↗
PubMed1985

Professional self-regulation: peer review.

Dentistry, in fulfilling its responsibility for self-regulation, has established a highly specific and formalized method of peer review. Its primary purpose is to mediate problems between patients, dentists, and third parties relative to the quality of treatment and appropriateness of care. It is a confidential service provided to the public and profession at no cost and accomplished with the voluntary cooperation of all parties involved. Decisions of peer review committees are advisory in nature but offer an alternative to legal resolution of misunderstandings and problems in patient care. The profession, by continually refining peer review and by educating its members and the public to its function, is providing a unique and valuable service to patients, dentists, and third parties. The objective and consistent application of this self-monitoring process is but one mechanism by which dentistry seeks to serve the public and perpetuate its high standard of care.

Dentists↗
PubMed1982

The effects of a continuing education course on dental hygiene practice.

Thirty-three dental hygienists were evaluated to measure the immediate and long-term effects of a continuing education course on their knowledge, attitudes, and clinical skills. The group demonstrated a significant gain in knowledge at the conclusion of the course. A postcourse evaluation was conducted after six months to determine students' ability to apply clinically the knowledge gained. the evaluation revealed no favorable change from the precourse state. Students rated themselves as having significantly improved in their ability to perform root planing, soft tissue curettage, and probing procedures from precourse to six months postcourse. No relationship was found between knowledge gained and students' evaluation of the effectiveness of the course.

Adult↗
PubMed1981

The effects on speech of surgical premaxillary osteotomy.

Patients were tested before and after undergoing surgical premaxillary osteotomy for correction of skeletal and soft-tissue discrepancies. Both structural and speech measurements were made before surgery and for a year after surgery. The role of hearing and oral sensation in adaptation to surgery was evaluated. Immediately after surgery, speech was disrupted. Distortions of /s/ predominated. However, there were non long-term effects on speech. Hearing and oral sensation played little role in adaptation.

Adult↗
PubMed1981

Computer graphics in facial morphology analysis.

Stereophotogrammetry is an attractive technique for mapping changes in facial form and contour following surgery. The need for trained personnel, however, has prevented the technique from gaining wide use. We report the development of a stereophotogrammetric system in combination with an inter-graphics computer system which overcomes this and other limitations. An interactive computer graphics system is used to record, present and manipulate the three-dimensional data obtained from a digitized stereophotogrammetric picture. The system also permits measurement of morphological changes following surgery as well as volume changes and has the potential for use in indicating the order in which multistage procedures should be undertaken and the time delay before such surgeries.

Cephalometry↗
PubMed1980

Posttreatment stability and esthetics of orthognathic surgery.

Several procedures were identified as important adjuncts to successful orthognathic results. Among these were the use of laminagraphic X-rays to monitor condyle displacement, condyle resorption and fibrous union problems. Other aspects involve gnathological errors in splint and positioner design, misdiagnosis because of a lack of soft-tissue analysis, differential treatment planning in deciding if surgery is needed, and understanding surgical effects on proportionality of the nose and lip esthetics.

Bone Resorption↗
PubMed1980

The effects of presentation of noise and dental appliances on speech.

The effects of dental appliances on speech were studied when subjects wore the appliances, both in quiet and in the presence of an intense noise. A group of 24 normal-speaking subjects read lists of syllables, words, and sentences and spoke spontaneously in each of six appliance and noise conditions. Several acoustic and perceptual measurements were made in each condition. In general, speech deteriorated when appliances were placed and when noise was presented. The type and amount of speech disruption varied as a function of speech task and aspect of speech. There was no evidence that the effects of appliances on speech differed in quiet and noise conditions. Inter-subject variability was large.

Adult↗
PubMed1980

The effects of noise and palatal appliances on the speech of five-year-old children.

Forty children of age five were divided into two groups according to articulation skill. Each child named pictures while wearing a palatal dental appliance in quiet and in the presence of an intense noise. Articulation errors and vocal intensity were measured in all conditions. Errors increased when appliances were placed and when noise was presented, but there was no interaction between the effects of appliances and noise on articulation. Intensity increased when noise was presented and decreased when appliances were placed. There was no interaction between the effects of appliances and noise on intensity. Children in the High and Low Articulation Skills groups did not differ in response to appliances or noise. The articulation results are very similar to results described earlier in an adult group. The children's vocal intensity changes were almost twice as large as those reported for the adult group. There may be a complex interaction between speech measure, type of feedback manipulation, and stage of development.

Auditory Perception↗