Objective: To determine the forces and moments delivered to a maxillary central incisor during rotation by three different thermoplastic appliances with identical thickness. Materials and Methods: Five identical appliances were manufactured from each of three materials (Ideal Clear 1.0 mm, Erkodur 1.0 mm, Biolon 1.0 mm). An upper central incisor fixed in a measuring device was rotated around its central axis in 0.5-degree steps to 62.5 degrees, 65 degrees, and 67.5 degrees (equivalent to an activation of 60.17 mm, 60.34 mm, and 60.51 mm of the incisor edge) in the clockwise and anticlockwise directions with the respective appliance fixed in place. For statistical analysis, the moments Tz (rotation) and forces Fz (intrusion) were tested. Means and standard deviations for Tz and median and 25% and 75% quantiles for Fz were calculated. An analysis of variance (ANOVA) was performed. Results: The minimal moment was determined at a rotation of 20.17 mm (27.3 Nmm, 60.8), and the maximal moment at a deflection of 20.51 mm (271.8 Nmm. 62.5) was recorded. The minimal value for Fz was measured at an activation of 20.17 mm (0.0 N), and the highest intrusive forces were evaluated for a rotation of 20.51 mm (25.8 N). The particular material sometimes had a significant (P , .05) influence on the forces delivered and the moments. Conclusions: During rotation with aligners, an intrusive force can also be observed. The direction of rotation, and the materials used all exert an influence on the force delivery properties of the appliance.

No abstract

Nonsyndromic orofacial clefts might affect family functioning and probably reduce the quality of life in school-age children and their parents. One hundred seventy consecutive children with orofacial clefts between 8 and 12 years and their families were asked to answer the Impact on Family Scale and KINDL. The results were compared with the quality of life in an age- and sex-matched group of unaffected schoolchildren. One hundred thirty-two families participated in this study. Family functioning was found superior in families with children with cleft lip than in families with children with cleft palate only or cleft lip and palate. Sex had no significant influence on family functioning. The quality of life in schoolchildren with orofacial clefts was found superior to the control group. Reductions were observed in children with cleft lip and palate in the dimensions "family" and "friends," indicating problems in the social field. Boys with orofacial clefts experienced a lower quality of life than girls. Children with cleft lip and palate and cleft palate only experienced a lower quality of life than children with cleft lip. Even years after successful cleft reconstruction, coping and mastering the diagnosis of orofacial cleft is a relevant concern for affected families. Several limitations of the quality of life in schoolchildren were identified, mostly affecting their social role.

The forces delivered by aligners during torquing have still not been investigated. The purpose of this study was to measure the forces delivered to an upper central incisor during torquing with three different materials of the same thickness, and to describe the biomechanical principles of torquing with aligners. Five identical appliances were manufactured from each of three materials, all with a thickness of 1.0 mm (Ideal Clear®, Erkodur®, and Biolon®). An upper central incisor, as part of the measuring device, was torqued in defined steps in the vestibular and palatal directions with the respective appliance in place. For statistical analysis, the resulting forces, Fx (forces acting in the palatal and facial directions) and Fz (intrusive force as a side-effect) at a displacement of ±0.15 and ±0.8 mm from the tooth at the gingival margin were calculated. The mean Fx forces for ±0.15 mm displacement ranged from -1.89 N [standard deviation (SD) 0.48] to 0.11 N (SD 0.1). The mean Fz forces were between -0.97 N (SD 0.57) and -0.07 N (SD 0.22). The highest intrusive forces were measured during palatal displacement of the measuring tooth. An influence of direction of displacement on the levels of force was observed, especially for Fz at the greater displacement of ±0.8 mm. In relation to the intended amount of root movement during torquing, aligners tend to 'lift up' and therefore no effective force couple can be established for further root control. The force delivery properties are also influenced by the material used and the shape of the tooth.

The force properties of thermoformed appliances have not been systematically investigated. Therefore, the aim of the present study was to quantify the forces delivered by thermoplastic appliances manufactured from three different materials, with the same thickness, on a central upper incisor, during tipping. Five identical appliances were manufactured from three different materials all with a thickness of 1.0 mm (Ideal Clear, Erkodur, and Biolon). For measuring the forces, an isolated measuring tooth, as part of a standardized resin model incorporated in a newly developed measuring device, was tipped in nine 2.7 arc minute (0.04629 degree) steps, from 0 to 0.416 degrees in the vestibular and palatal directions around a rotational axis through the virtual apex, after positioning an appliance on the model. For statistical analysis, the force components Fx/tipping and Fz/intrusion at a displacement of +/-0.151 mm from the incisor edge were determined. Means and standard deviations (SDs) were calculated. The Kruskal-Wallis test for overall effects and the Wilcoxon two-sample test for individual group pairings were used (P < 0.05 significance level). The mean Fx forces ranged from -2.82 N (SD 0.62) to 5.42 N (SD 0.56). The mean Fz forces were between -0.14 N (SD 0.52) and -2.3 N (SD 0.43). The highest intrusive forces were measured during vestibular displacement of the measuring tooth. The forces delivered by the Biolon appliance were found to be much greater (P < 0.01) than those of the other materials. The forces delivered by the materials investigated were mostly higher than those stated in the literature.

Underlying mechanisms of action need to be addressed in depth by future research.

Objective: To determine the forces and moments delivered to a maxillary central incisor during rotation with aligners when a simulated occlusal force generated during swallowing acts on the appliance. Materials and Methods: Five identical appliances were manufactured from four different starting materials (Erkodur 0.8 mm and 1.0 mm; Biolon 0.75 mm and 1.0 mm). An upper central incisor fixed in a measuring device was rotated around its central axis in 0.5-degree steps up to 610 degrees with the appliance fixed in place. An occlusal force of 30 N generated during swallowing was simulated with a weight positioned on the appliance. For statistical analysis, the moments Tz (rotation) and forces Fz (intrusion) at a deflection of 60.34 mm to the incisor edge (65 degrees rotation) were tested. Means and standard deviations for Tz and median and 25% and 75% quartiles for Fz were calculated. An analysis of variance was performed.

Piezosurgery caused reduced somatosensory impairment and a faster recovery of somatosensory functions in the present investigation.