The "8020" goal of retaining 20 or more teeth after the age of 80 necessitates investigating oral health status in people below the age of 80. The purpose of this study was to determine similarities and differences between people in their sixties attending college and achievers of the 8020 goal. The results of oral examination and occlusal force measurement in 46 students enrolled at a college for the elderly in Chiba City with an average age of 66.9 years (22 men, 24 women) were compared with data from previous surveys of fifty-two 8020 achievers (28 men, 24 women). Occlusal force was measured and evaluated using Dental Prescale (Fuji Photo Film Co., Tokyo). The average number of present teeth was 25.8, and no subjects showed anterior crossbite, comparable with findings in 8020 achievers. Average occlusal force was ‫1.044ע9.249‬ N ‫9.545ע6.920,1(‬ N for men, ‫1.503ע4.368‬ N for women), not significantly different from that in 8020 achievers. The results of multiple regression analysis suggest that occlusal force is unaffected by aging if many teeth are present.

Surgical orthodontic treatment has been reported to improve oral health-related quality of life (OHRQL). Such treatment comprises three stages: pre-surgical orthodontic treatment; orthognathic surgery; and post-surgical orthodontic treatment. Most studies have focused on change in OHRQL between before and after surgery. However, it is also necessary to evaluate OHRQL at the pre-surgical orthodontic treatment stage, as it may be negatively affected by dental decompensation compared with at pre-treatment. The purpose of this prospective study was to investigate the influence of surgical orthodontic treatment on QOL by assessing change in condition-specific QOL at each stage of treatment in skeletal class III cases. Twenty skeletal class III patients requiring surgical orthodontic treatment were enrolled in the study. Each patient completed the Orthognathic Quality of Life Questionnaire (OQLQ), which was developed for patients with dentofacial deformity. Its items are grouped into 4 domains: "social aspects of dentofacial deformity"; "facial esthetics"; "oral function"; and "awareness of dentofacial esthetics". The questionnaire was completed at the pre-treatment, pre-surgical orthodontic treatment, and post-surgical orthodontic treatment stages. The results revealed a significant worsening in scores between at pre-treatment and pre-surgical orthodontic treatment in the domains of facial esthetics and oral function (p<0.01), and between at pre-surgical orthodontic and post-surgical orthodontic treatment in all domains except awareness of dentofacial esthetics (p<0.05, p<0.01). A significant correlation was observed between a negative change in overjet and worsening OQLQ scores at the pre-surgical orthodontic treatment stage. Significant correlations were also observed between improvement in upper and lower lip difference, soft tissue pogonion protrusion, and ANB angle and improvement in OQLQ scores at the post-surgical orthodontic treatment stage. These results indicate that morphologic change influences OHRQL in patients undergoing surgical orthodontic treatment not only after surgery, but also during pre-surgical orthodontic treatment.

The maxillofacial region of patients with facial asymmetry is deformed not only in the mandible but also in the maxilla, suggesting that the head region may also be deformed. Therefore, in this study, skeletally originated mandibular prognathism with facial asymmetry was evaluated in relation to cranial morphology. The cranial morphology of patients who visited the Chiba Dental Center of Tokyo Dental College and were diagnosed with skeletal mandibular prognathism with facial asymmetry (asymmetry group: ANB 0° or less; Menton deviation 4 mm or more; 30 subjects) and without facial asymmetry (symmetry group: ANB less than 0°; Menton deviation less than 3 mm) was measured and evaluated. As a method, the length and area of the cranium were measured using axial cephalometric radiographs. In the asymmetry group, there was a significant difference in the left–right difference in the long diameter of the posterior part of the cranium compared to the symmetry group (p = 0.009). The asymmetry group also had significant differences in the central and occipital areas of the cranium on the left and right sides compared to the symmetry group (p < 0.001). In the asymmetry group, the direction of Menton deviation and the direction of head region deviation coincided in about 70% of the cases. There was also a positive correlation between head deviation and the amount of Menton deviation. The results of this study suggested that patients with facial asymmetry had greater head deformity than patients without facial asymmetry.

Fully automated techniques using convolutional neural networks for cephalometric landmark detection have recently advanced. However, all existing studies have adopted X-rays. The problem of direct exposure of patients to X-ray radiation remains unsolved. We propose a model for detecting cephalometric landmarks using only facial profile images without X-rays. First, the model estimates the landmark coordinates using the features of facial profile images through high-resolution representation learning. Second, considering the spatial relationship of the landmarks, the model refines the estimated coordinates. The estimated coordinates are input into fully connected networks to improve the accuracy. During the experiment, a total of 2000 facial profile images collected from 2000 female patients were used. Experiments results demonstrated that the proposed method exhibits a better performance than advanced methods trained with X-rays. We obtained an MRE of 0.61 mm for the test data and a mean detection rate of 98.20% within 2 mm. Our proposed two-stage learning method enables a highly accurate estimation of the landmark positions using only facial profile images. The results indicate that X-rays may not be required when detecting cephalometric landmarks.

No abstract

A lateral load was applied to anchor screws that had undergone surface treatment, and the structure, cellular dynamics, and quality of the bone surrounding anchor screws were analyzed to investigate the effect of this surface treatment on the peri-implant jawbone. In addition, bone microstructural characteristics were quantitatively evaluated for each site of loading on the bone around the anchor screw. Rats were euthanized after observation on days 3, 5, or 7, and bone quality analyses were performed. Bone–implant contact rate increased more rapidly at an early stage in the treated surface group than in the untreated surface group. Bone lacuna morphometry showed that the measured values adjacent to the screw at the screw neck on the compressed side (A) and at the screw tip on the uncompressed side (D) were significantly lower than those at the screw tip on the compressed side (B) and at the screw neck on the uncompressed side (C). Collagen fiber bundle diameter showed that the measured values adjacent to regions A and D were significantly higher than those at regions B and C. Anchor screw surface activation facilitates initial bone contact of the screw, suggesting that early loading may be possible in clinical practice.

Temporary anchorage devices (TADs) allow molar intrusion as an additional treatment option to conventional treatment for open bite cases. We investigated the treatment option criteria for open bite treatment. A total of 33 patients with skeletal Class I to Class II open bite who had stable occlusion one year after treatment were enrolled in the study, including 15 patients who had undergone surgical orthodontic treatment, 8 patients who had undergone treatment with molar intrusion, and 10 patients who had undergone treatment with anterior teeth extrusion. Pre-treatment cephalometric analysis of these patients was used for comparison. Furthermore, receiver operating characteristic (ROC) curve analysis was employed to examine the measurement parameters that would be valid as treatment criteria. In the results, FMA showed that patients treated with molar intrusion had a moderately high angle, while those treated with surgical orthodontic treatment had a severe high angle. The area under the curve (AUC) of the ROC curve indicated that FMA is the most appropriate parameter for treatment option criteria. In addition, the cutoff value indicated that the borderline between molar intrusion and surgical orthodontic treatment was 37.5° for FMA. In this study, we suggested criteria for the treatment of open bite with molar intrusion.

The objective of this study was to determine whether the distribution of compressional and tensional stress around tooth roots is influenced by the position of a temporary anchorage device and the length of the retraction hook during the distalization of the maxillary dentition. A photoelastic orthodontic model was made of photoelastic epoxy resin. Six combinations of three retraction hook lengths and two posterior Temporary skeletal anchorage devices (TAD) positions were established. Stress was applied through an elastic chain for each of the combinations. Digital photoelastic stress analysis measured the compression, tensional stress, and direction around the tooth root. Using this novel photoelastic model, we found that the distribution of compressional and tensional stress during the retraction of the maxillary dentition was significantly influenced by the position of the TAD and the length of the retraction hook.