Class II treatment success rate in 2- and 4-premolar extraction protocols

Variáveis relevantes no tratamento da má oclusão de Classe II

“…Accordingly, a higher success rate in Class II treatment can be achieved with only two upper extractions. However, in spite of the fact that a Class II malocclusion treatment protocol with two upper extractions has proved more efficient 5,14,15 and more likely to provide a Class I cuspid relationship 6,15 by affording an adequate anterior guide and a reasonable posterior occlusal relationship, some authors still persist in the mistaken belief that finishing a treatment with a complete Class II molar relationship can be detrimental to a functional occlusion 21 .…”

“…Although Class II malocclusion treatment with the extraction of two upper premolars does yield a greater success rate 5,8,15 , the belief that a vertical facial pattern has a negative bearing on the treatment results might indicate that the four-extraction protocol would be preferable in such cases. It was then speculated that the less-than-satisfactory results achieved with the Class II four-premolar extraction treatment might be more due to the deleterious influence of an unfavorable facial pattern than to a difficulty in correcting Class II molar relationship, as required by this treatment protocol.…”

“…Therefore, in Class II cases where the correction of cephalometric discrepancy required extractions, the repositioning of lower incisors towards the lingual region ultimately increased anteroposterior discrepancy between the lower segments of the arches, sometimes compromising treatment results 25 . As a matter of fact, subsequent studies have shed light on the difficulties that arise in trying to balance the Class II anteroposterior relationship when extractions are made in the lower arch 6,15 . As a result, extractions performed with the sole purpose of correcting cephalometric discrepancy have been questioned in Class II treatment, and even more so in the presence of an excellent dental alignment.…”

“…Assuming that lower incisors are more vertically positioned and that facial height control is more crucial for patients who have a vertical facial pattern, the indication to perform extractions in the lower arch of this patient group can be considered stronger than in patients whose facial pattern is either horizontal or balanced 26 . Regardless of the facial pattern, however, lower arch extractions should not be performed when treating Class II if the sole purpose is to correct cephalometric discrepancy or to control vertical dimension since the difficulty in correcting anteroposterior discrepancy between the arches is compounded in comparison with the treatment protocol involving the extraction of two upper premolars 5,6,15,16 . On the other hand, if the treatment protocol is conducted with no extractions the need to move upper molars towards distal not only undermines vertical dimension control 20 , but it also makes it harder to accomplish the correction of anteroposterior discrepancy between the arches than would be the case if the treatment involving two upper extraction were put in place 14 .…”

“…Success rate in Class II malocclusion treatment can be significantly influenced by factors such as treatment protocol 1,11 , malocclusion severity 3,7 , patient age 23 and degree of patient compliance 15 . Since malocclusion severity and age are inherent patient characteristics which are, therefore, defined ahead of time, these variables are beyond professional control.…”