Takami Itoh

Biomechanical effects of maxillary protraction on the craniofacial complex

The deformational effects on the human skull resulting from maxillary protraction were examined by means of strain gauges and displacement transducers. A maxillary protraction appliance was used that included a reverse headgear attached to the maxillary first molars. The protraction forces that were applied to this appliance were parallel to the occlusal plane at the following locations: the height of the maxillary arch, 5 mm above the palatal plane, and 10 mm above the Frankfort horizontal plane. The results indicated that protraction forces at the level of the maxillary arch produced an anterior rotation and forward movement of the maxilla, protraction forces 10 mm above the Frankfort horizontal plane produced a posterior rotation of the maxilla with a forward movement of nasion, and protraction forces 5 mm above the palatal plane produced a combination of parallel forward movement and a very slight anterior rotation of the maxilla. Moreover, constriction of the anterior part of the palate occurred in all cases.

Effect of contamination and etching on enamel bond strength of new light-cured glass ionomer cements.

The effect of water and saliva contamination on the bond strength of metal orthodontic brackets cemented to etched (10% polyacrylic acid) and unetched human premolar enamel was investigated. Two bonding agents were used: one commercially available product (LC) and one experimental (EX) light-cured glass ionomer. Shear bond strength was measured after aging for 5 minutes, 15 minutes, and 24 hours. The results were compared by ANOVA and Scheffes tests at p = 0.05. For LC, the bond strength of brackets bonded to etched enamel, with and without contamination, was statistically higher than that of brackets bonded to unetched enamel for all aging times. An exception was the bond strength to unetched enamel with saliva contamination after 24 hours; for EX, this value was statistically higher than that measured on unetched enamel with water contamination. Contamination by saliva did not reduce bond strength to unetched enamel. For both etched and unetched enamel, there was no significant difference between LC and EX after 24 hours for all contamination conditions.

Bonding of light-cured glass ionomer cement to polycarbonate resin treated with experimental primers.

The effect of experimental primers on the shear bond strength of polycarbonate composite resin with light-cured glass ionomer cements was investigated. Mixtures of methylmethacrylate (MMA) with the comonomers 2-hydroxyethyl methacrylate (HEMA), triethyleneglycol methacrylate (TEGDMA), and bisphenol-A-glycidymethacrylate (bisGMA) were used as primers. Polycarbonate composite resin rods of circular cross section and plates were bonded, with and without precured and nonprecured primers, using 2 light-cured glass ionomer cements (commercially available [LC] and experimental [EX]). In addition, commercial polycarbonate composite resin brackets with precured 50% TEGDMA/MMA primer were bonded to etched human enamel with both cements. Shear bond strengths were measured. Results were compared by ANOVA and Scheffes tests at P = .05. The 30% HEMA/MMA, 50% TEGDMA/ MMA, 10% bisGMA/MMA, and 30% bisGMA/MMA primers produced the higher shear bond strengths (9.5 to 20.8 MPa) with LC and EX to polycarbonate composite resin. The 50% TEGDMA/MMA primer was most effective in improving the shear bond strengths of both LC and EX. Precured 50% TEGDMA/ MMA primer on a commercial resin bracket was effective in providing good shear bond strength to enamel.

A Case of Mandibular Prognathism Treated by Orthognathic Surgery with Schizophrenia

Schizophrenia is an inherent disease that causes disruption of thinking patterns, sensing, self-esteem, will and emotions, resulting in mental disorder involving hallucinations and other mental symptoms.The major complaint of this 21-year-old female patient with skeletal mandibular protrusion was thought to be pain of the temporomandibular region. However, upon careful analysis based on Narrative Based Medicine, the primary concern was the mandibular protrusion with asymmetry inducing multiple psychological symptoms. Combined ortho-surgical intervention was performed to resolve this patients problem. Although increased antidepressant intake was noted prior to the surgery, once the treatment had been performed, resulting in major improvements of the profile and appearance, dramatic mental and psychological changes for the better were noted, allowing this patients return to a healthy and normal social life along with decreased dependency on anti-depressant drugs.

Mandibular Prognathism and Anterior Open Bite: Treatment by Orthodontic Molar Intrusion and Two-jaw Surgery

Abstract This article reports a case of non-surgical molar intrusion using the skeletal anchorage system as a presurgical adjunct to the correction of mandibular prognathism with severe anterior open bite. It is suggested that such treatment is feasible and may be chosen to diminish the surgical burden of the planned operation.

A Case of Surgical Orthodontic Treatment of Deformed Healing with the Widening Upper Dental Arch by Trauma

In this case, widening and scissors bite of left upper dental arch was observed as a complication after fracture. Le Fort I type osteotomy of the left maxilla and palatine suture osteotomy were performed and the constriction of the upper dental arch by using a rapid maxillary contraction appliance was rendered. As compared with before the treatment, 2.0mm reduction of maxillary arch on P-A cephalogram, and 3.3mm reduction of the distance of central incisors, 3.9mm reduction of the distance of first bicuspids and 2.6mm reduction of the distance of first molars were observed in the model. Following treatment, the occlusions and aesthetic feeling were recovered satisfactorily in a short time.