In vitro measurement of frictional forces in ceramic and stainless steel direct-bonded edgewise...
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Thesis abstracts The concordance of pretreatment malocclusion assessments among orthodontic specialty practitioners K. G. Todd Rowe, DMD, MPH Ann "Arbor, Michigan: University of Michigan, 1989 This investigation was undertaken in an attempt to determine the perceived distinction between malocclu- sion severity and treatment difficulty among orthodontic specialists. Thirty orthodontists were asked to review the pretreatment records of six orthodontic patients and to complete a questionnaire for each patient regarding the severity of the malocclusion, anticipated difficulty in treating the malocclusion, and the likelihood of an ideal result being a treatment goal for each patient. Difficulty in correcting the various specified compo- nents of each of the malocclusions was also addressed. The patients were evaluated according to the Summers Occlusal Index and were selected to represent a broad range of "objective" malocclusion severities. Results indicate that orthodontists can distinguish between patients with regard to malocclusion severity and treatment difficulty (ANOVA, p < 0.001). More- over, Student t tests and correlation coefficients indicate that orthodontists can distinguish between malocclusion severity and treatment difficulty among patients. Con- version of raw scores to relative weighted ranks produce coefficients of concordance that assessed the level of agreement between multiple examiners for a range of patients regarding the perceived attributes of malocclu- sion. There is more examiner agreement regarding mal- occlusion severity than treatment difficulty. It is concluded that malocclusion severity and treat- ment difficulty are distinct but related entities. The pro- portion of orthodontists distinguishing between mal- occlusion severity and treatment difficulty is dependent on the defined criteria for determining a difference between the relative scores. Standard components of malocclusion--overbite, overjet, alignment, arch width, dental/skeletal Class I relationships, and soft tissue balance--are not reliable predictors of either overall perceived malocclusion severity or of treatment difficulty. In vitro measurement of frictional forces in ceramic and stainless steel direct-bonded edgewise orthodontic brackets M. Cohen,' G. Meir,= and R. Hayes' Philadelphia, Pennsylvania: Temple University and Drexel University,2 1989 An in vitro investigation was conducted to measure and to compare the static and kinetic frictional force 384 characteristics of 0.018 × 0.025-inch slot ceramic and stainless steel orthodontic brackets of the same me- siodistal widths. A universal material-testing machine and a specially designed testing fixture were used to pull 0.016-inch round and 0.016 × 0.022-inch rectan- gular stainless steel wires through various test brackets at controlled speeds. Static and kinetic frictional forces were recorded at various second-order angulations be- tween brackets and arch wires. In general, the study revealed the forces required to translate wires through ceramic brackets are greater than the forces required with stainless steel brackets under identical testing conditions (other than at 0 ° bracket inclination). The elastomeric ligature •frictional forces were the dominant forces at 0 ° bracket inclinations and were of comparable magnitude for both ceramic and stainless steel brackets. Additional findings were that the forces required to translate a rectangular wire were greater than the forces required to translate a round wire-and that the kinetic frictional forces for ceramic brackets were more vari- able and unstable than those for stainless steel brackets. A computer-controlled testing method has been de- veloped to systematically measure frictional forces for any desired wire/bracket combination. Salivary S. mutans levels before, during, and after orthodontic treatment Richard G. Rosenbloom, DMD Farmington, Conn.: University of Connecticut, 1989 Patients undergoing orthodontic therapy have oral ecologic changes such as a low pH environment, in- creased retentive sites for S. mtttans, and increased food retention that may lead to increased proportions and absolute numbers of S. mutans. These changes may be responsible, in part, for the observations of posttreat- ment decalcification in certain cases. It is not clear from previous studies, however, whether the infection level ofS. mlllalls remains elevated after orthodontic therapy. The purpose ot ~this study was to evaluate salivary S. mutans levels in patients before, during, and after orthodontic treatment. The 75 subjects in this essen- tially cross-sectional study were assigned to five groups, each consisting of 15 subjects: 12- to 15-year-olds in active treatment; a retention group that consisted of subjects from the active treatment group who were lon- gitudinally followed 6 to 15 weeks after removal of appliances; a postretention group of 16- to 21-year-old subjects who had not worn any intraoral appliances for the past 4 to 18 months; and two untreated control groups, one aged 12 to 15 years and the other aged 16 to 21 years. Salivary samples were collected from each
Transcript of In vitro measurement of frictional forces in ceramic and stainless steel direct-bonded edgewise...
Thesis abstracts
The concordance of pretreatment malocclusion assessments among orthodontic specialty practitioners K. G. Todd Rowe, DMD, MPH Ann "Arbor, Michigan: University of Michigan, 1989
This investigation was undertaken in an attempt to determine the perceived distinction between malocclu- sion severity and treatment difficulty among orthodontic specialists. Thirty orthodontists were asked to review the pretreatment records of six orthodontic patients and to complete a questionnaire for each patient regarding the severity of the malocclusion, anticipated difficulty in treating the malocclusion, and the likelihood of an ideal result being a treatment goal for each patient. Difficulty in correcting the various specified compo- nents of each of the malocclusions was also addressed. The patients were evaluated according to the Summers Occlusal Index and were selected to represent a broad range of "objective" malocclusion severities.
Results indicate that orthodontists can distinguish between patients with regard to malocclusion severity and treatment difficulty (ANOVA, p < 0.001). More- over, Student t tests and correlation coefficients indicate that orthodontists can distinguish between malocclusion severity and treatment difficulty among patients. Con- version of raw scores to relative weighted ranks produce coefficients of concordance that assessed the level of agreement between multiple examiners for a range of patients regarding the perceived attributes of malocclu- sion. There is more examiner agreement regarding mal- occlusion severity than treatment difficulty.
It is concluded that malocclusion severity and treat- ment difficulty are distinct but related entities. The pro- portion of orthodontists distinguishing between mal- occlusion severity and treatment difficulty is dependent on the defined criteria for determining a difference between the relative scores. Standard components of malocclusion--overbite, overjet, alignment, arch width, dental/skeletal Class I relationships, and soft tissue ba lance--are not reliable predictors of either overall perceived malocclusion severity or of treatment difficulty.
In vitro measurement of frictional forces in ceramic and stainless steel direct-bonded edgewise orthodontic brackets M. Cohen,' G. Meir, = and R. Hayes' Philadelphia, Pennsylvania: Temple University and Drexel University, 2 1989
An in vitro investigation was conducted to measure and to compare the static and kinetic frictional force
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characteristics of 0.018 × 0.025-inch slot ceramic and stainless steel orthodontic brackets of the same me- siodistal widths. A universal material-testing machine and a specially designed testing fixture were used to pull 0.016-inch round and 0.016 × 0.022-inch rectan- gular stainless steel wires through various test brackets at controlled speeds. Static and kinetic frictional forces were recorded at various second-order angulations be- tween brackets and arch wires.
In general, the study revealed the forces required to translate wires through ceramic brackets are greater than the forces required with stainless steel brackets under identical testing conditions (other than at 0 ° bracket inclination). The elastomeric ligature • frictional forces were the dominant forces at 0 ° bracket inclinations and were of comparable magnitude for both ceramic and stainless steel brackets.
Additional findings were that the forces required to translate a rectangular wire were greater than the forces required to translate a round wire-and that the kinetic frictional forces for ceramic brackets were more vari- able and unstable than those for stainless steel brackets.
A computer-controlled testing method has been de- veloped to systematically measure frictional forces for any desired wire/bracket combination.
Salivary S. mutans levels before, during, and after orthodontic treatment Richard G. Rosenbloom, DMD Farmington, Conn.: University of Connecticut, 1989
Patients undergoing orthodontic therapy have oral ecologic changes such as a low pH environment, in- creased retentive sites for S. mtttans, and increased food retention that may lead to increased proportions and absolute numbers of S. mutans . These changes may be responsible, in part, for the observations of posttreat- ment decalcification in certain cases. It is not clear from previous studies, however, whether the infection level ofS. mlllalls remains elevated after orthodontic therapy.
The purpose ot ~ this study was to evaluate salivary S. mutans levels in patients before, during, and after orthodontic treatment. The 75 subjects in this essen- tially cross-sectional study were assigned to five groups, each consisting of 15 subjects: 12- to 15-year-olds in active treatment; a retention group that consisted of subjects from the active treatment group who were lon- gitudinally followed 6 to 15 weeks after removal of appliances; a postretention group of 16- to 21-year-old subjects who had not worn any intraoral appliances for the past 4 to 18 months; and two untreated control groups, one aged 12 to 15 years and the other aged 16 to 21 years. Salivary samples were collected from each
