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Objective@# By analyzing changes of dental arch width and length during the aligning and leveling period (non-extraction case) with two kinds of self-locking bracket, compare the difference between the active self-locking bracket with the passive bracket.@*Methods@#The data of dental arch perimeter change amount and dental arch width and length change amount (WU/L3, WU/L4, WU/L5, WU/L6, U/LL) were statistically analyzed using the correlation and regression method by comparing active and passive brackets for the correction of dental arch variations. Two different brackets for the correction of the measured values of the dental arch variations was analyzed by t-test. Results There were statistical relationships between the amount of arch perimeter increase and the amount of width and length increase. The regression equation was statistically significant (P < 0.05), It was greater impacted arch width increase to arch perimeter in the self-locking. The t-test results showed WU3, WL3, WL6, LR 4 measured values (P < 0.05) statistically significant in the active self-locking group and passive group. @*Results @#There were statistical relationships between the amount of arch perimeter increase and the amount of width and length increase. The regression equation was statistically significant (P < 0.05), It was greater impacted arch width increase to arch perimeter in the self-locking. The t-test results showed WU3, WL3, WL6, LR 4 measured values (P < 0.05) statistically significant in the active self-locking group and passive group. @*Conclusin @#Active and passive self-locking bracket have good arch expansion effecting. The active self-locking bracket is slightly dominant than the passive bracket in the expansion of the canine width whereas the active self-locking bracket is better than the passive in the expansion of the mandibular first molar and arch perimeter which should be widely applied to the appropriate cases.
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Objective To analyze the effects of self-ligating bracket on enlarging the maxillary alveolar arch and to investigate the the non-extraction treatment programs.Methods All patients were used heat activated basic and precise theory for the orthodontist in order to make a plan fordeveloping nickel-titanium wire,then assessed by occlusalplane analysis method.The maxillary model andcephalometric radiographs were collected and measured before the treatment.The data of the resultswereanalyzed.Results After the treatment,the increase of the width of the dental arch was related to the /FMA,crowding degree and canines initial position.The increase of arch length was related to the ∠ANB,crowding degree,malocclusion classification,canines initial position andthe second molar eruption.Conclusion The essential factors include the crowding degree of arch,∠FMA,∠ANB,the angle of the anterior teeth,malocclusion classification,canines initial position andthe second molar eruptioncan affect the result of non-extraction quick self-ligating bracket appliance treatment on enlarging the maxillary alveolar.
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Objective:To evaluate dental and skeletal changes following slow maxillary expansion with quad helix using Cone-Beam computer tomography (CBCT).Methods:13 patients(5males and 8 females,mean age 14.38 ±2.22 years)requiring maxillary ex-pansion as a part of their comprehensive orthodontic treatment were included.Each patient had CBCT images taken pre-(T1 )and post-(T2)maxillary expansion with quad helix.Changes of the distances between bilateral canines,first premolars,second premo-lars,first molars,the width of basal bone and palatal suture were measured.paired t-test results were analyzed using SPSS 17.0 soft-ware.Results:The distances between the 4 bilateral teeth increased by (2.47 ±1.05)mm,(2.97 ±1.90)mm,(2.79 ±1.21) mm and (3.15 ±1.15)mm,the apical distances decreased by (1.19 ±0.40)mm,(2.12 ±0.68)mm,(2.02 ±0.65)mm and (1.34 ±0.63)mm,respectively.The inclination of the first molars were decreased by (4.45 ±2.86)°and (4.02 ±1.45)°on the left and right side respectively.The width of basal bone and palatal suture increased by (2.37 ±0.96)mm and (1.21 ±0.50)mm respectively,the differences between T1 and T2 were all statistically different(P <0.001).Conclusion:Quad helix expands maxil-lary arch by greater dental changes than by skeletal changes.
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BACKGROUND: Rapid expansion of the dental arch is an effective way to rapidly expanse the jaw. Compared with rapid expansion, the slow expansion has higher stability and less recurrence, but the reports on the long-term stability of quad helix expansion are rare. OBJECTIVE: To retrospectively analyze the clinical effect of quad helix expansion in orthodontics. METHODS: Twenty-two subjects with dental arch stenosis in mixed dentition and early permanent dentition who experienced an expansion of at least 3 mm with quad helix appliance were selected for this study. Plaster dental casts and posteroanterior radiographs were evaluated at the beginning of the treatment (T1), at the completion of phase I quad helix expansion or ful treatment (T2), and approximately 2 years fol owing the completion of treatment (T3). The distance between two first molars was measured on the model. J point was drawn on the posteroanterior radiograph in order to measure the distance between the bilateral base bones and the molar inclination, as wel as to evaluate the corrective and orthopedic effects of dental arch expansion. RESULTS AND CONCLUSION: Compared with that before expansion, the first permanent molar inclination and the distance between base bones on two sides were significant increased after quad helix expansion; there were no significant differences in the distance between two first permanent molars, first permanent molar inclination and the distance between bilateral base bones on two sides when compared after quad helix expansion and after 2-year fol ow-up (P > 0.05). The results indicate that the long-term effect of quad helix expansion is stable with orthopedic effect.
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Tooth size arch length discrepancy (TSALD) is one of the main reasons for crowding and malocclusion. Expansion of the dental arch is one of the ways to achieve space .The main challenge is to hold the teeth in the corrected position after cross bite correction. This case report describes one simple and easy way to retain the molars in the corrected position. It is simple and easy and does not require fabrication of any special appliance and can be worn and used during the period of fixed orthodontic therapy without much discomfort to the patient.
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Objective:To study the effects of treatment of Angle Ⅱ division 2 malocclusion with upper/lower arch expansion and Class Ⅱ elastics in adults. Methods:Expanding upper/lower arch and Class Ⅱ elastic were used to treat Angle Class Ⅱ division 2 malocclusion in 15 adults. Study models and cephalograms were analyzed before and after treatment. Results:Before and after treatment the maxillary variables of cephalograms showed no significant differences, the mandibular variables showed significant differences in sagittal and vertical direction. U1-NA, U1-PP, L1-NB, L1-MP, U1-L1 and L6-Ptm were significantly increased after treatment(P