Sweden and Martina (Italy)

Background: The present in vitro study aimed to investigate the fatigue performance of different dental fixtures in two different emergence profiles. Biological failures are frequently reported because the problem canonly be solved by replacing a failing implant with a new one. Clinicians addressed minor mechanical failures, such as bending, loosening or the fracture of screws, abutment, or the entire prosthesis, by simply replacing or fixing them. Methods: Transmucosal and submerged bone-level dental implants underwent fatigue strength tests (statical and dynamical performance) by a standardized test: UNI EN ISO 14801:2016. Two types of emergence profiles (Premium sub-crestal straight implant with a cylindrical-shaped coronal emergence or Prama one-piece cylindrical-shape implant with transmucosal convergent neck and hyperbolic geometry) were tested, and dynamic fatigue were run to failure. Data was analyzed by a suitable statistical tool. Results: The Wöhler curve of 0.38 cm Premium group c2, appeared to be significantly different from that of the 0.38 cm Prama group c3 (nonparametric one-way ANOVA χ2 = 6; degree of freedom = 1; probability = 0.0043) but not from that of the 0.33 cm Premium group c1 (nonparametric one-way ANOVA χ2 = 0.62; degree of freedom = 1; probability = 0.4328). Fatigue performance of configuration 2 was one and a half times better than that of configuration 3. Group c3 had a better ultimate failure load (421.6 ± 12.5 N) than the other two settings i.e., c1 (324.5 ± 5.5 N) and c2 (396.3 ± 5.6) reaching almost a nonsignificant level. Conclusions: It was observed that a transmucosal implant design could provide the highest resistance to static fracture. On the other hand, an equicrestal implant design could increase dynamic endurance.

The present study aimed to evaluate the cephalometric effects of a headgear anchored to the deciduous second molars in the early mixed dentition. Study design: The study followed a retrospective longitudinal design and enrolled 31 consecutive patients (17 females and 14 males) treated with high pull (HP) headgear anchored to the deciduous second molars, average age 8y 5m± 5m at pre-treatment time (T0) and 9y 8m± 6m at post-treatment time (T1). All the patients wore the headgear for approximately 8-10 hours at night, with a force of 250 g per side. The active phase of treatment ended once patients obtained a distal step on permanent molars of at least 2 mm. Lateral cephalograms at T0 and T1 were taken; 10 angular measurements were chosen as variables of the study. The paired sample t-test was employed to assess the significance of the differences of each variable between T0 and T1. In this group of Class II patients, HP headgear anchored to the deciduous second molars in the early mixed dentition produced: significant reduction of SNA angle, significant increase of SN/NL angle with no significant change in SN/ML angle, significant labial flaring of upper incisors. As clinically evaluated, the correction of the Class II occlusal relationship and the anterior crowding of maxillary arch were also accomplished.