Can we estimate root axis using a 3-dimensional tooth model via lingual-surface intraoral scanning?

INTRODUCTION: This research aimed to compare the estimation error of the root axis using 3-dimensional (3D) tooth models at the midtreatment stage between the whole-surface scan (WSS) and lingual-surface scan (LSS) methods. METHODS: The sample consisted of 208 teeth (26 each of central incisors, canines, second premolars, and first molars in the maxillary and mandibular dentition) from 13 patients whose pre- and midtreatment intraoral scan and cone-beam computed tomography (CBCT) were available. The 3D tooth models were constructed by merging the intraoral-scan crowns and the CBCT-scan roots obtained at the pretreatment stage. To estimate the root axis at the midtreatment stage, we superimposed the individual 3D tooth models onto the midtreatment intraoral scan obtained by the WSS and LSS methods. The midtreatment CBCT scan was used as the gold standard to determine the real root axis. The estimated root axis in terms of mesiodistal angulation and buccolingual inclination was measured in the WSS and LSS methods, and statistical analysis was performed. RESULTS: The estimation errors of the mesiodistal angulation and buccolingual inclination were <2.0° in both methods. The LSS method demonstrated a statistically larger but clinically insignificant estimation error than the WSS method in the mandibular canine (mesiodistal angulation, 1.95° vs 1.62°) and the total tested teeth (mesiodistal angulation, 1.40° vs 1.29°; buccolingual inclination, 1.51° vs 1.41°). CONCLUSIONS: Because the estimation errors of the root axis angle using the 3D tooth model by the WSS and LSS methods were within the clinically acceptable range, the root axis can be estimated by both methods.

The effects of isometric exercise types on pain and muscle activity in patients with low back pain.

The purpose of the present study is to evaluate the effects of isometric exercise types on low back pain (LBP) patients. Isometric exercise types were mat exercise and I-Zer exercise. Subjects were divided into 3 groups: LBP control group, LBP mat exercise group, and LBP I-Zer exercise group in 23-25 aged men. Visual analogue scale (VAS) and electromyography (EMG) were used to evaluate the degree of pain and the muscle activity in LBP patients. Root mean square (RMS), median frequency (MDF), and mean frequency (MNF) were checked by EMG power spectrum analysis on longissimus thoracic (LT), iliocostalis lumborum (IL), mulitifidus (M), and rectus abdominis (RA). LBP mat exercise program and LBP I-Zer exercise program were conducted 5 sets once time, 3 times per week during 6 weeks. The two-way ANOVA with repeated measure was used to check the pain degree and muscle activity. The present results showed that muscle activity in the LBP I-Zer exercise group was increased compared to the LBP mat exercise group and LBP control group (P<0.05). LBP I-Zer exercise group and LBP mat exercise group showed increased mean frequency in LT, IL, M, and RA muscles than the LBP control group. Therefore, LBP patients performed isometric exercise may have positive effect to reduce pain degree and to increase muscle activity. Especially, LBP I-Zer exercise type showed more effectiveness in reducing pain degree and enhancing muscle activity.

Antidepressants modulate glycine action in rat hippocampus.

Antidepressants are drugs that relieve symptoms of depressive disorders. Fluoxetine, tianeptine, and milnacipran are different types of antidepressants, and they have widely been used for relieving of depression symptoms. In the present study, the effects of fluoxetine, tianeptine, and milnacipran on the glycine-induced ion current by nystatin-perforated patch clamp and on the amplitude of field potential in the hippocampal CA1 region by multichannel extracellular recording, MED64, system, were studied. In the present results, fluoxetine, tianeptine, and milnacipran reduced glycine-induced ion current in the hippocampal CA1 neurons in nystatin-perforated patch clamp method. These drugs enhanced the amplitude of the field potential in the hippocampal CA1 region in MED64 system. These results suggest that antidepressants may increase neuronal activity by enhancing field potential through inhibition on glycine-induced ion current.