ABSTRACT
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.
ABSTRACT
OBJETIVO: determinar o perímetro de arco adicional necessário para o nivelamento da curva de Spee através de uma técnica laboratorial em modelos de estudo. MÉTODOS: foram utilizados 70 modelos inferiores nos quais se mediu a profundidade da curva de Spee e o perímetro do arco (de segundo molar a segundo molar). Nos mesmos modelos, após a simulação do nivelamento da curva de Spee, o perímetro de arco foi novamente avaliado, mantendo sua forma e comprimento. RESULTADOS: foi confirmada a correlação entre a profundidade da curva de Spee e o perímetro de arco adicional, sendo deduzida a fórmula [Paa = 0,21 CSmax - 0,04]. CONCLUSÃO: a técnica proposta permitiu, através da avaliação do perímetro de arco com curva de Spee nivelada, a determinação do espaço disponível para o alinhamento dentário.
AIM: To determine the additional arch perimeter needed for leveling the curve of Spee by means of a laboratory technique using dental casts. METHODS: Seventy lower dental models were used for measuring the depth of the curve of Spee and assessing the arch perimeter from second molar to second molar. In these dental casts, after simulation of leveling the curve of Spee, arch perimeter was reevaluated, after maintaining its form and length. RESULTS: The correlation between the depth of the curve of Spee and the additional arch perimeter was ratified, as can be shown by the formula [Paa = 0,21 CSmax - 0,04]. CONCLUSION: The proposed technique allowed, through the assessment of the arch perimeter with the leveled curve of Spee, the determination of the space available for tooth alignment.
Subject(s)
Dental Arch , Dental Occlusion , Tooth Movement Techniques , Casts, SurgicalABSTRACT
Predicting the arch length discrepancy by simply comparing the available arch perimeter with tooth materials is merely a 2-dimensional analysis of the teeth movement. However, the real teeth movement takes place 3-dimensionally and is affected by various factors such as, the arch form, the curve of Spee and the axis of the incisors. The purpose of this study is to clarify the relationship between the decrease in the arch perimeter and the horizontal positional change of the incisors after extraction of the 1st bicuspids, for more analytic evaluation of the arch length discrepancy at pre-treatment model analysis stage. In addition to that to evaluate the effect of the curve of Spee, teeth axis to the basal plane, and the incisional crowding to the treatment outcome. All patients were treated at the department of orthodontics, dental hospital, Yonsei university. Inclusion criteria for patients selection were as follows. -Angle classification I malocclusion with bialveolar protrusion -Extraction of 4 1st bicuspids -No tooth anomaly or prosthesis -No abnormal attrition -No ectopically erupted teeth -Angle classification I canine and molar relationship -Less than 3mm of crowding Model analysis of the above patients was performed and the following conclusions were obtained. 1. When the intercanine distance was maintained, the available space for the distal movement of the mandibular incisors after the extraction of the 4 1st bicuspids was larger than the space provided by the extraction of the 4 1st bicuspids. However the difference was less than 1mm. The more tapered the anterior arch form, the larger the difference. 2. Compared to the situation in which the intercanine distance was maintained, when the intercanine distance was expanded to meet the width of the posterior teeth, the incisors could move about 3mm more distally. 3. The positional difference of the incisal tip was insignificant whether the central incisors were moved by tipping or bodily movement. 4. When the anterior crowding was solved without changing the intercanine distance, the larger the anterior arch length was, the more the anterior movement of the incisors. 5. When the curve of Spee was levelled, the increase in the arch perimeter was less than half of the deepest curve of Spee.