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ObjectiveThe purpose of this study was to compare the treatment duration and dentoskeletal changes between two different anchorage systems used to treat maxillary dentoalveolar protrusion and to examine the effectiveness of en-masse retraction using two miniscrews placed in the midpalatal suture.MethodsFifty-seven patients (9 men, 48 women), who had undergone level anchorage system treatment at Aichi-Gakuin University Dental Hospital (Nagoya, Japan) were divided into two groups according to the method of maxillary posterior anchorage reinforcement: midpalatal miniscrews (25 patients, mean age 22 years) and conventional anchorage (32 patients, mean age 19 years). The en-masse retraction period, overall treatment duration, pre-treatment effective ANB angle, and change in the effective ANB angle were compared with an independent-samples t-test.ResultsCompared to the headgear group, the duration of en-masse retraction was longer by approximately 4 months in the miniscrew group (p < 0.001). However, we found no significant difference in the total treatment duration between the groups. Moreover, a greater change in the effective ANB angle was observed in patients treated with miniscrews than in those treated with the conventional method (p < 0.05).ConclusionsThe level anchorage system treatment using miniscrews placed in the midpalatal area will allow orthodontists more time to control the anterior teeth during en-masse retraction, without increasing the total treatment duration. Furthermore, it achieves better dentoskeletal control than does the conventional anchorage method, thereby improving the quality of the treatment results.

Pulsed laser welding of AISI 304 stainless steel plate was simulated using commercial finite element software to determine the optimal welding conditions. Due to geometric symmetry, only one plate was modeled to reduce the simulation computation time. User subroutines were created to account for a moving three-dimensional heat source and to apply boundary conditions. The material properties such as conductivity, specific heat, and mass density were determined as functions of temperature. The latent heat was considered within the given temperature range. The three-dimensional heat source model for pulsed laser beam butt welding was designed by comparing the finite element analysis results and experimental data. This successful simulation of pulsed Nd:YAG laser welding for AISI 304 stainless steel will prove useful for determining optimal welding conditions.