- Email: [email protected]
A radiographic comparison of apical root resorption following orthodontic treatment with the edgewise and speed applicances
198
Reviews and abstracts
fected/surfaces at risk) was the best predictor of fimtre damage (difference between pretreatment and posttreatment DMF) with a r value of 0.513 (p = 0.01). The higher the initial attack rate the greater the damage. There was no correlation between the banded plaque score and Cariescre.en (r = 0.058). There was no correlation between the plaque score and damage (r = 0.118), or Cariescreen and damage (r = - 0 . 0 5 8 ) .
A comparative analysis of frictional forces between self-Iigatlng and conventional edgewide orthodontic brackets. D. W. Kemp, Toronto, Ontario, Canada: Faculty of Dentistry, University of Toronto, 1992
A significant amount of applied force may be lost to frictional resistance during sliding mechanics. It is believed that self-ligating bracket systems have lower levels of frictional resistance that conventional tie-bracket systems. This is because the ligating clips of the self-ligating brackets possess a smaller magnitude of force seating the arch wire into the bracket slot relative to the steel or elastomerie ligatures of the conventional systems. Tl~e purpose of this research investigation was to test the hypothesis that self-ligating bracket systems have less frictional resistance than tie-wing systems. A testing apparatus was constructed to simulate the clinical situation in which a maxillary right canine is retracted through a first premolar extraction space along a continuous arch wire, with sliding mechanics. The bracket could be translated straight along the wire, or it could have a 10~ second order tip present. Speed, Activa, and American 0.022 x 0.028-inch brackets were tested with 0.018-inch and 0.019 x 0.025-inch arch wires of stainless steel, Nitinol and TMA alloys, at both 0 ~ and 10~ of second order tip. Mean and standard error of the mean was calculated for each bracket/wire combination. A four factor Anova test was performed to determine whether there was an appliance effect (Speed versus Activa versus American), an arch wire alloy effect (stainless steel versus TMA versus Nitinol), an arch wire size effect (0.018 versus 0.019 x 0.025 inch), or a second order angulation effect (0 ~ versus 10~ The results demonstrated that the hypothesis was accepted. At the 0 ~ second order angulation, Activa brackets demonstrated the lowest levels of friction, followed by Speed atzd Americaa, respectively. All are statistically significantly different (p < O.O001) from each other. Stainless steel wires showed significantly less friction ( p . < 0.0001) than both TMA and Nitinol, which are not significantly different from each other. .' At the 10 ~ second order angulation, the American bracket was statistically higher (p < 0.01) than both the Activa and Speed, which were not significantly different from each other. T.MA was the highest in terms of frictional resistance, followed by stainless steel, and Nitinol, respectively, with each being significantly different from each other (p < 0.0001). The smaller round arch wires exhibit significantly lower fric-
American Journal of Orthodontics and DentofaciatOrthopedics February 1993
tion than the larger rectangular wires at both 0 ~ and 10~ and for all alloys (p < 0.0001). Second order tipping of the bracket relative to arch wire created significantly more friction than straight linear translation, and is more clinically relevant as some degree of tooth tipping is always present clinically.
A radiographic comparison of apical root resorption following orthodontic treatment with the edgewise and Speed appliances. Marielle Flannelly Blake, Toronto, Canada: University of Toronto, 1992
Apical root resorption is a serious iatrogenic problem associated with orthodontic treatment.. Because the Speed appliance provides a continuous rotatory and torque action through its spring clip mechanism, it has been suggested that more apical root resorption might be expected than with use of the conventional edgewise appliance. The effect of continuous action on root resorption compared with the interrupted action of the edgewise system has not been investigated previously. The purpose of the present research investigation was to test the null hypothesis that there is no difference in the apical root resorption seen after orthodontic treatment with the edgewise straight wire and the Speed appliance systems. Prctreatment and posttreatment periapical radiographs of 63 patients (30 treated with the Speed 0.018-inch bracket and 33 with the American 0.018-inch edgewise bracket) were studied. Quantitative measurements of crown and root lengths for the maxillary and mandibular central and lateral incisors were compared. The long cone paralleling technique was used for all the radiographs. Any image distortion between the pretreatment and posttreatment radiograph was calculated and compensated for by using the crown length measurements, on the assumption that the crown length remains unaltered during the treatment period. Means and standard deviations for the percentage root resorption per tooth group were calculated. A three factor analysis of variances (ANOVA test) was performed to determine whether there was an appliance, treatment, or gender effect on the amount of root resorption seen after treatment. No statistically significant difference in root resorption between the two appliance systems was found. More root resorption was evident in the extraction group for upper lateral incisors (p < 0.05). An appliance-gender interaction was evident for some teeth, with the edgewise male group showing more root resorption than the Speed male group (p < 0.05).
The relationship of condylar position to cephalometric analysis. R. W. Stryker and L. LetteR, Fort Meade, Maryland: V. S. Army Orthodontic Residenc), 1992
Thei'e has been speculation that condylar position may be related to craniofacial relationships. The purpose of this study was to evaluate the possible relationship between condylar position changes from centrie relation to maximum intercuspation and cephalometrie analysis.
Reviews and abstracts
fected/surfaces at risk) was the best predictor of fimtre damage (difference between pretreatment and posttreatment DMF) with a r value of 0.513 (p = 0.01). The higher the initial attack rate the greater the damage. There was no correlation between the banded plaque score and Cariescre.en (r = 0.058). There was no correlation between the plaque score and damage (r = 0.118), or Cariescreen and damage (r = - 0 . 0 5 8 ) .
A comparative analysis of frictional forces between self-Iigatlng and conventional edgewide orthodontic brackets. D. W. Kemp, Toronto, Ontario, Canada: Faculty of Dentistry, University of Toronto, 1992
A significant amount of applied force may be lost to frictional resistance during sliding mechanics. It is believed that self-ligating bracket systems have lower levels of frictional resistance that conventional tie-bracket systems. This is because the ligating clips of the self-ligating brackets possess a smaller magnitude of force seating the arch wire into the bracket slot relative to the steel or elastomerie ligatures of the conventional systems. Tl~e purpose of this research investigation was to test the hypothesis that self-ligating bracket systems have less frictional resistance than tie-wing systems. A testing apparatus was constructed to simulate the clinical situation in which a maxillary right canine is retracted through a first premolar extraction space along a continuous arch wire, with sliding mechanics. The bracket could be translated straight along the wire, or it could have a 10~ second order tip present. Speed, Activa, and American 0.022 x 0.028-inch brackets were tested with 0.018-inch and 0.019 x 0.025-inch arch wires of stainless steel, Nitinol and TMA alloys, at both 0 ~ and 10~ of second order tip. Mean and standard error of the mean was calculated for each bracket/wire combination. A four factor Anova test was performed to determine whether there was an appliance effect (Speed versus Activa versus American), an arch wire alloy effect (stainless steel versus TMA versus Nitinol), an arch wire size effect (0.018 versus 0.019 x 0.025 inch), or a second order angulation effect (0 ~ versus 10~ The results demonstrated that the hypothesis was accepted. At the 0 ~ second order angulation, Activa brackets demonstrated the lowest levels of friction, followed by Speed atzd Americaa, respectively. All are statistically significantly different (p < O.O001) from each other. Stainless steel wires showed significantly less friction ( p . < 0.0001) than both TMA and Nitinol, which are not significantly different from each other. .' At the 10 ~ second order angulation, the American bracket was statistically higher (p < 0.01) than both the Activa and Speed, which were not significantly different from each other. T.MA was the highest in terms of frictional resistance, followed by stainless steel, and Nitinol, respectively, with each being significantly different from each other (p < 0.0001). The smaller round arch wires exhibit significantly lower fric-
American Journal of Orthodontics and DentofaciatOrthopedics February 1993
tion than the larger rectangular wires at both 0 ~ and 10~ and for all alloys (p < 0.0001). Second order tipping of the bracket relative to arch wire created significantly more friction than straight linear translation, and is more clinically relevant as some degree of tooth tipping is always present clinically.
A radiographic comparison of apical root resorption following orthodontic treatment with the edgewise and Speed appliances. Marielle Flannelly Blake, Toronto, Canada: University of Toronto, 1992
Apical root resorption is a serious iatrogenic problem associated with orthodontic treatment.. Because the Speed appliance provides a continuous rotatory and torque action through its spring clip mechanism, it has been suggested that more apical root resorption might be expected than with use of the conventional edgewise appliance. The effect of continuous action on root resorption compared with the interrupted action of the edgewise system has not been investigated previously. The purpose of the present research investigation was to test the null hypothesis that there is no difference in the apical root resorption seen after orthodontic treatment with the edgewise straight wire and the Speed appliance systems. Prctreatment and posttreatment periapical radiographs of 63 patients (30 treated with the Speed 0.018-inch bracket and 33 with the American 0.018-inch edgewise bracket) were studied. Quantitative measurements of crown and root lengths for the maxillary and mandibular central and lateral incisors were compared. The long cone paralleling technique was used for all the radiographs. Any image distortion between the pretreatment and posttreatment radiograph was calculated and compensated for by using the crown length measurements, on the assumption that the crown length remains unaltered during the treatment period. Means and standard deviations for the percentage root resorption per tooth group were calculated. A three factor analysis of variances (ANOVA test) was performed to determine whether there was an appliance, treatment, or gender effect on the amount of root resorption seen after treatment. No statistically significant difference in root resorption between the two appliance systems was found. More root resorption was evident in the extraction group for upper lateral incisors (p < 0.05). An appliance-gender interaction was evident for some teeth, with the edgewise male group showing more root resorption than the Speed male group (p < 0.05).
The relationship of condylar position to cephalometric analysis. R. W. Stryker and L. LetteR, Fort Meade, Maryland: V. S. Army Orthodontic Residenc), 1992
Thei'e has been speculation that condylar position may be related to craniofacial relationships. The purpose of this study was to evaluate the possible relationship between condylar position changes from centrie relation to maximum intercuspation and cephalometrie analysis.