Anchorage quality of deciduous molars versus premolars for molar distalization with a pendulum appliance

Purpose: The aim of this study was to assess dental anchorage qualities when the pendulum appliance is used for distal molar movement. Material: Thirty adolescents in various dentition stages received a modified pendulum appliance with a distal screw and a specially preactivated pendulum spring for bilateral molar distalization in the maxilla. The subjects were subcategorized into 3 groups of 10 according to the dental anchorage used: deciduous molars, premolars and deciduous molars, or only premolars. Dentoalveolar effects and side effects in the anchorage unit and in the molar area were determined by cephalometric analysis. Results: Statistical analysis of the measurements showed significant differences between groups in the extent of molar distalization and the resulting incisor protrusion. Distal tipping of the 6-year molars was significantly less severe (2.3° ± 1.58° to the palatal plane and 2.55° ± 1.52° to the anterior cranial base) in patients with premolar anchorage than in those with deciduous molar anchorage (6.15° ± 3.42° and 6.35° ± 3.46°). Incisor protrusion was significantly more pronounced in patients with deciduous molar anchorage (2.75 ± 1.4 mm) than in the other 2 groups (1.65 ± 0.82 mm, mixed deciduous molar and premolar anchorage, and 1.75 ± 0.75 mm, premolar anchorage). Additionally, incisor protrusion was translatory compared with controlled tipping in subjects with deciduous molar anchorage or premolar and deciduous molar anchorage. Conclusions: Deciduous molars and premolars can be used for anchorage for molar distalization with a pendulum appliance; however, anchorage with premolars only results in the least pronounced dentoalveolar side effects. The anchorage quality of deciduous molar and mixed deciduous molar/premolar anchorage is limited.