Effect of anodization on friction behavior of ß­titanium orthodontic archwires.

PURPOSE: To evaluate the effects of anodization on the friction behavior of beta-titanium (ß-Ti) orthodontic archwires in conventional or self-ligating brackets in vitro. METHODS: ß­Ti archwires (0.018â€¯× 0.025 inch) pre- and postanodization were tested in combination with 0.022-inch stainless steel conventional and self-ligating brackets. The surface composition and oxide thickness of the ß­Ti archwires pre- and postanodization were measured using Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). Detailed surface topography and roughness were assessed using atomic force microscopy (AFM). Surface topographies of the ß­Ti archwires pre- and postanodization were examined using scanning electron microscopy (SEM). Friction was measured using a universal testing machine; the data were statistically analyzed. RESULTS: Postanodization, the identified titanium oxide layer on the surface of the ß­Ti archwires increased in thickness from 10 to 100 nm; at the same time, the values for surface roughness were significantly reduced by half (p < 0.001). The archwire surfaces post anodization were harder and had fewer scratches after the friction test. Anodization significantly reduced 23.77% of the static (p < 0.01) and 25.61% of the kinetic (p < 0.001) friction of the ß­Ti archwires in conventional brackets, while it significantly reduced 85.71% of the static and 84.38% of the kinetic friction (p < 0.01) in self-ligating brackets. CONCLUSION: Anodization reduced the ß­Ti archwire friction, which was particularly more effective in combination with self-ligating brackets. The friction reduction via anodization could be attributed to the increased thickness, surface hardness, and decreased surface roughness of the titanium oxide layer.

Comparison between microporous and nanoporous orthodontic miniscrews : An experimental study in rabbits.

PURPOSE: Surface characteristics of orthodontic miniscrews might affect survival rates and removal torque values (RTVs). This experimental study aimed to clarify whether and why a microporous or nanoporous surface promotes higher survival rates and RTVs for orthodontic miniscrews. METHODS: Using a split-leg design, one set each of nonporous (sham control, n = 24) and microporous (control, n = 6), and three sets of nanoporous (experimental, n = 6 per set) miniscrews were implanted in the tibias of 12 New Zealand rabbits and immediately loaded with 1.5 N nickel-titanium coil springs for 12 weeks. The surface morphology, micropores, and nanotube diameters of the miniscrews were examined using scanning electron microscopy and field-emission scanning electron microscopy. The surface composition and thickness were determined using Auger electron spectroscopy. The survival rates and RTVs of each set were assessed. RESULTS: The nanoporous miniscrews had higher survival rates, RTVs (p < 0.001), and thicker nanotube oxide thicknesses (p < 0.001) than the nonporous and microporous miniscrews. The nonporous and microporous miniscrews had no nanotube structures. The surface oxide composition was titanium dioxide (TiO2). The threshold RTV, TiO2 thickness, and nanotube diameter of nanoporous miniscrews needed to promote the experimental survival rate to 100% was determined to be 6.6 ± 0.8 N-cm (p < 0.05), 22.5 ± 4.8 nm (p < 0.05), and 17.6 ± 2.3 nm or above, respectively. CONCLUSION: Nanoporous surfaces promoted higher survival rates and RTVs than microporous miniscrews. This could be due to TiO2 nanotube structures with thicker oxide layers in nanoporous miniscrews.

Orthognathic Surgery with Simultaneous Autologous Fat Transfer for Correction of Facial Asymmetry.

BACKGROUND: Most patients treated with orthognathic surgery for facial asymmetry would value improvement in residual soft-tissue asymmetry. Autologous fat transfer is widely used to augment facial soft tissue. The authors assessed the effect of combining orthognathic surgery with autologous fat transfer for treating patients with facial asymmetry. METHODS: In this retrospective study, 15 consecutive adults underwent combined orthognathic surgery and autologous fat transfer between January of 2013 and December of 2015. Lower facial profile symmetry was assessed using postoperative standard frontal photographs. RESULTS: Lower facial symmetry was much improved by combining orthognathic surgery and autologous fat injection. CONCLUSION: The combined use of orthognathic surgery and autologous fat transfer is a promising technique for improving facial symmetry in patients with facial asymmetry. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Vertical skeletal and facial profile changes after surgical correction of mandibular prognathism.

BACKGROUND: Mandibular prognathism is often corrected by surgical orthodontics. Correction of the sagittal facial profile has received wide attention. However, vertical changes remained undefined and thus, were investigated. METHODS: Subjects included 18 patients with mandibular prognathism who had surgical correction (S group, mean age: 20.1 +/- 3.2 years) and 18 patients with Class I malocclusion (C group, mean age: 21.2 +/- 3.6 years). Cephalograms were taken at the initial visit (T1) for both the groups and one year after surgery (T2) for the S group and analyzed by standard protocols. The vertical differences between the S and C groups at T1 and within the S group at T1 and T2 were compared. Additionally, the C group at T1 and the S group at T2 were compared. RESULTS: Comparison between groups at T1 revealed no difference in the anterior and posterior upper facial heights (58 mm and 50 mm, respectively). However, the S group exhibited a longer anterior lower facial height and a shorter posterior lower facial height. Accordingly, any vertical measurements and comparisons related to the mandible revealed significant difference between groups. Surgical correction did not change the vertical chin position. Contrarily, the posterior ramus heights were reduced (from 54 to 50 mm). The vertical measurements and comparisons for soft tissues reflected those for hard tissues. CONCLUSIONS: The results indicate that through surgical correction of mandibular prognathism, vertical facial heights can be maintained within normal physiological function.