Objectives of mixed dentition treatment in orthodontics

Abstract

During the early mixed dentition, facial structures are passing through a period of rapid development, with growth centers that are at the peak of their activity. Orthodontics should take advantage of this developmental phase rather than permit it to proceed in an unfavorable direction. Moving upper first permanent molars distally in developing Class II malocclusions places these teeth in their proper positions in relation to other skeletal structures; it also sets the stage for the subsequent eruption of the remaining permanent teeth into their normal occlusal positions with their lower opponents. Conversely, if left untreated, all the remaining unerupted teeth ultimately will assume the same Class II positions as the malposed upper first molars. Structural imbalance will increase, as will muscular imbalance also, and each will add to the severity of the other if these misdirected forces are permitted to continue without interruption. The picture then will be that of a fully matured dental deformity after growth has ceased and the damage has been done. Treatment of these more severe malocclusions can often be accomplished without extraction, but early treatment provides greater insurance against an extraction compromise. At an early age, moreover, response is rapid and excellent results can be achieved with a minimum of mechanical therapy compared to that required when treatment is postponed to the permanent dentition. Despite the fact that these may appear to be “easy” cases, this is not a procedure to apply indiscriminately in every potential patient who, when first examined, appears to be progressing into an authentic Class II malocclusion. The greater challenge lies in a precise diagnosis. This demands an exacting study based not on technical skill but on analytical judgment and extensive experience in the correction of all types of malocclusion if improper treatment is to be avoided. A differentiation must be made between those cases that need immediate attention and those that should be postponed for comprehensive treatment during the postpubertal “growth spurt.” At such an early age, moreover, there is no pressing urgency for a diagnostic decision. A more conservative approach is to first place these children under periodic observation to determine the future developmental trend, for some of these irregularities tend to become self-corrective with the passing of time. The recurring question is whether sufficient development can be created to accommodate all the teeth. We have no reliable method of predicting growth; yet we do not have the right to discount it entirely in the preliminary diagnosis and treatment of these patients. Even with potential premolar extraction cases, the prudent course is first to attempt correction with a full complement of teeth. It takes only a few months to determine whether it can be done, and the sense of accomplishment is gratifying indeed when extraction can be avoided. This should always be our goal, and we should take every precaution to attain it.