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Comparative radiographic study of heavy intermittent and light continuous forces
196
Am. J. Orthodontics February 1969
Reviews and abstracts
Both experimental groups showed significant decreases in angle SNA. The length of the hard palate increased significantly in the control and hook-on groups. Oaklane Professional Center l’housand Oaks, C!alif. 91560
Third Molar Teeth and Their Effect Upon the lower Anterior Teeth; Q Study of Forty-nine Orthodontic Cases 5 Years After Band Removal Jack Sheneman Saint Lock- University,
St. Lowis,
MO.
The purpose of this investigation was to study the effect of mandibular third molars upon the mandibular anterior teeth. Dental casts and lateral cephalometric roentgenograms of forty-nine cases were selected from the files of the Saint Louis University Department of Orthodontics, Twenty-one linear and angular measurements were made and recorded from pretreatment, band removal, and posttreatment casts and lateral cephalometric roentgenograms. Recorded data were analyzed statistically and mean values were compared on the basis of six; for individuals with third molars in occlusion, third molars unerupted, and third molars missing ; and for Class I nonextraction, Class I extraction, Class II nonextraction, and Class II extraction categories of treatment. A high degree of correlation was noted with those variables generally accepted for orthodontic diagnosis, such as amount of reduction of ANB to be anticipated during treatment, amount of pogonion increase to be expected, and stability of the pretreatment intercanine width measurement for the individual. The results of this pilot study indicate that further effort should be applied to research in the effects of mandibular third molar teeth upon lower anterior teeth in orthodontically treated cases. In the cases studied, relatively more stability was seen in the patients with third molars congenitally missing than in those whose third molars were present. Box 78 Po7.xm. Mont.
Comparative Continuous Richard Saint
Radiographic Forces
1. Bostyan University,
Louis
St. Lowis,
Study of Heavy
Intermittent
and light
MO.
The comparative effects on dental tissues of heavy intermittent and light continuous forces in orthodontic movement were studied radiographically. An edgewise appliance was used for the heavy intermittent force in the bodily retraction of a tooth. An appliance utilizing the Begg principle was employed for the light continuous force in the retraction of a tooth by tipping. Both appliances were placed in the same experimental animal, a rhesus monkey, for a more controlled comparison.
Reviews
Volume 55 Number 2
and
abstracts
197
Occlusal amalgam restorations and a gold implant served as radiographic landmarks to evaluate the amount and type of movement produced by each appliance. Occlusal and periapical radiographs were taken at predetermined intervals of 48 hours, 3 weeks, and 6 weeks. Exposure factors of 90 KVP and 15 Ma. were used for all projections. A stereotaxic instrument based on the principle of a Broadbent cephalostat was constructed to position the head and jaws of the animal in the same spatial relationship for each radiograph. An assessment of tooth movement and an evaluation of the tissue response to the force system used was made from each radiograph. The radiographs revealed bodily movement on the side of the heavy intermittent force and tipping on the side of the light continuous force. The tipping movement of the light continuous force produced slightly more linear movement of the clinical crown than the bodily movement of the heavy intermittent force side. After 3 weeks, there was a definite reciprocal displacement of the apex in the tipping action on the side of the light continuous force. Sites of primary and secondary resorption appeared at the alveolar crest adjacent to the distal root and mesial to the apical third of the roots on the tipped teeth. The location of centroid was determined at infinity on the side of bodily movement by the heavy intermittent force. In the tipping action of the light continuous force, centroid was determined as a point between the bifurcated roots and at a distance halfway between the alveolar crest and the root apex. 563 N. Peninmda Dr. Daytona Beach, Fla. 36018
Analgesic
Structure-Activity
on a Series of Dihydroanthracenes
Victor S. DeGeorge, D.D.S., MS. Saint Louis University, St. Louis, MO.
One of the best tests for screening analgesic activity is the phenylquinone writhing response used in this study. Results from the phenylquinone tests were compared with the results from two other tests-the hexobarbital potentiation test and the hot plate test. The method used for the phenylquinone test was a modification of others which have been previously used. Groups of six mice were used to test a series of twenty-one dihydroanthracene compounds. Two special plastic cages, each with six compartments to allow isolation of each mouse, were devised. Each mouse in a group was injected subcutaneously with a calculated dose of the test drug. Following an absorption period, each mouse was injected intraperitoneally with the writhing agent, phenylquinone. The response was manifested by a rotating, twisting movement which was distinct and easily counted on a hand tally counter. Obviously, the more active the test drug, the greater the protection and the fewer the writhes. This procedure was repeated for at least three scaled doses of each of the twenty-one dihydroanthracenes, and a dose-activity curve was plotted for each. ED,, values, the doses at which 50 per cent of the mice were affected, and con-
Am. J. Orthodontics February 1969
Reviews and abstracts
Both experimental groups showed significant decreases in angle SNA. The length of the hard palate increased significantly in the control and hook-on groups. Oaklane Professional Center l’housand Oaks, C!alif. 91560
Third Molar Teeth and Their Effect Upon the lower Anterior Teeth; Q Study of Forty-nine Orthodontic Cases 5 Years After Band Removal Jack Sheneman Saint Lock- University,
St. Lowis,
MO.
The purpose of this investigation was to study the effect of mandibular third molars upon the mandibular anterior teeth. Dental casts and lateral cephalometric roentgenograms of forty-nine cases were selected from the files of the Saint Louis University Department of Orthodontics, Twenty-one linear and angular measurements were made and recorded from pretreatment, band removal, and posttreatment casts and lateral cephalometric roentgenograms. Recorded data were analyzed statistically and mean values were compared on the basis of six; for individuals with third molars in occlusion, third molars unerupted, and third molars missing ; and for Class I nonextraction, Class I extraction, Class II nonextraction, and Class II extraction categories of treatment. A high degree of correlation was noted with those variables generally accepted for orthodontic diagnosis, such as amount of reduction of ANB to be anticipated during treatment, amount of pogonion increase to be expected, and stability of the pretreatment intercanine width measurement for the individual. The results of this pilot study indicate that further effort should be applied to research in the effects of mandibular third molar teeth upon lower anterior teeth in orthodontically treated cases. In the cases studied, relatively more stability was seen in the patients with third molars congenitally missing than in those whose third molars were present. Box 78 Po7.xm. Mont.
Comparative Continuous Richard Saint
Radiographic Forces
1. Bostyan University,
Louis
St. Lowis,
Study of Heavy
Intermittent
and light
MO.
The comparative effects on dental tissues of heavy intermittent and light continuous forces in orthodontic movement were studied radiographically. An edgewise appliance was used for the heavy intermittent force in the bodily retraction of a tooth. An appliance utilizing the Begg principle was employed for the light continuous force in the retraction of a tooth by tipping. Both appliances were placed in the same experimental animal, a rhesus monkey, for a more controlled comparison.
Reviews
Volume 55 Number 2
and
abstracts
197
Occlusal amalgam restorations and a gold implant served as radiographic landmarks to evaluate the amount and type of movement produced by each appliance. Occlusal and periapical radiographs were taken at predetermined intervals of 48 hours, 3 weeks, and 6 weeks. Exposure factors of 90 KVP and 15 Ma. were used for all projections. A stereotaxic instrument based on the principle of a Broadbent cephalostat was constructed to position the head and jaws of the animal in the same spatial relationship for each radiograph. An assessment of tooth movement and an evaluation of the tissue response to the force system used was made from each radiograph. The radiographs revealed bodily movement on the side of the heavy intermittent force and tipping on the side of the light continuous force. The tipping movement of the light continuous force produced slightly more linear movement of the clinical crown than the bodily movement of the heavy intermittent force side. After 3 weeks, there was a definite reciprocal displacement of the apex in the tipping action on the side of the light continuous force. Sites of primary and secondary resorption appeared at the alveolar crest adjacent to the distal root and mesial to the apical third of the roots on the tipped teeth. The location of centroid was determined at infinity on the side of bodily movement by the heavy intermittent force. In the tipping action of the light continuous force, centroid was determined as a point between the bifurcated roots and at a distance halfway between the alveolar crest and the root apex. 563 N. Peninmda Dr. Daytona Beach, Fla. 36018
Analgesic
Structure-Activity
on a Series of Dihydroanthracenes
Victor S. DeGeorge, D.D.S., MS. Saint Louis University, St. Louis, MO.
One of the best tests for screening analgesic activity is the phenylquinone writhing response used in this study. Results from the phenylquinone tests were compared with the results from two other tests-the hexobarbital potentiation test and the hot plate test. The method used for the phenylquinone test was a modification of others which have been previously used. Groups of six mice were used to test a series of twenty-one dihydroanthracene compounds. Two special plastic cages, each with six compartments to allow isolation of each mouse, were devised. Each mouse in a group was injected subcutaneously with a calculated dose of the test drug. Following an absorption period, each mouse was injected intraperitoneally with the writhing agent, phenylquinone. The response was manifested by a rotating, twisting movement which was distinct and easily counted on a hand tally counter. Obviously, the more active the test drug, the greater the protection and the fewer the writhes. This procedure was repeated for at least three scaled doses of each of the twenty-one dihydroanthracenes, and a dose-activity curve was plotted for each. ED,, values, the doses at which 50 per cent of the mice were affected, and con-