On tooth movement

Current concepts of clinical orthodontic tooth movement are misleading. Traditionally, these have been described as dependent on force levels and being tipping/bodily in nature. The following is a reevaluation of the relationships between tooth movement and orthodontic mechanotherapy not usually considered when analyzing tooth movement clinically. It is our contention that confusion as to the biological response(s) to mechanical force is derived from in vivo orthodontic trials where conditions are undefined. This correlates with variable biological responses within the periodontium. Constantly changing moment to force ratios inherent to the dynamic load deflection rates of any system used to move a tooth cause changing tendencies for crown/root tipping. This implies that the accepted notion of static translatory tooth movement, although a useful didactic concept, is currently unattainable. In actuality, it has never been documented empirically using any conventional orthodontic appliance.