The Physiological Function of Deglutition and Swallowing in Patients With Maxillary Protrusion After Mandibular Advancement.

The objective of this study was to determine the tongue-palatal contact changes in patients with skeletal maxillary protrusion after sagittal split ramus osteotomy (SSRO) during swallowing. In this study, 15 patients with maxillary protrusion and 10 normal subjects participated. Before and 3 months after surgery, tongue-palatal contact patterns during swallowing of patients with maxillary protrusion as well as controls were evaluated by electropalatography. The electrode contact number in the alveolar, palatal, and velar parts was examined. The swallowing duration of each phase was also evaluated. In the lateral area of the velar part, incomplete electrode contact was shown at 0.3 seconds in patients with maxillary protrusion. The electrode contact number in the velar part at 0.3 seconds before tongue-palatal complete contact was significantly less in the preoperative patients compared with the controls ( P < 0.05). A small increase in the electrode contact number of the velar part was shown in the postoperative patients at 0.3 and 0.2 seconds before tongue-palatal complete contact ( P < 0.05). The pharyngeal phase duration was significantly larger in the patients with maxillary protrusion before SSRO compared with the controls ( P < 0.05). After SSRO, the pharyngeal phase duration was significantly shortened. It was shown that the tongue-palatal contact pattern during swallowing in patients with maxillary protrusion improved after orthognathic surgery, and the pharyngeal phase duration was also shortened. It is suggested that the changes in the mesiodistal mandibular position by orthognathic surgery can improve tongue posture and movement during swallowing.

An Investigation of Tongue-Palatal Contact Changes in Patients With Skeletal Mandibular Lateral Deviation After Sagittal Split Ramus Osteotomy.

ABSTRACT: This study aimed to investigate the changes in tongue-palatal contact patterns in patients with mandibular lateral deviation by electropalatography (EPG) before and after sagittal split ramus osteotomy (SSRO). Ten mandibular asymmetry patients who underwent SSRO participated in the study. Tongue-palatal contact patterns for the production of /t/ and /s/ sounds were observed using EPG before surgery and 3 months after surgery, and the changes in EPG pattern were examined. The number of electrode contacts in the 2 vertical columns of the EPG plate was calculated both in the mandibular deviation side and the nondeviation side. The EPG patterns for /t/ and /s/ showed asymmetry before surgery but became normal after surgery. Before surgery, the number of electrode contacts in the 2 vertical columns in the mandibular deviation side was significantly lower than that in the nondeviation side and the normal participants during /t/ and /s/ articulation. However, the number of electrode contacts in the deviation side significantly increased after surgery. This study demonstrated that the tongue-palatal contact patterns for /t/ and /s/ articulation shifted to the direction of mandibular deviation and improved after SSRO.

Changes in tongue-palatal contact during swallowing in patients with skeletal mandibular prognathism after orthognathic surgery.

This study aimed to evaluate improvement of tongue-palatal contact patterns during swallowing after orthognathic surgery in mandibular prognathism patients. Thirty patients with mandibular prognathism treated by orthognathic surgery (average age of 27 years, 3 months) and 10 controls (average age 29 years, 6 months) participated in this study. Tongue-palatal contact patterns of patients before and three months after surgery were evaluated by electropalatography (EPG) as well as controls. Whole total of tongue-palatal contact at 0.3, 0.2, and 0.1 sec before complete tongue-palatal contact during swallowing were evaluated. The duration of swallowing phases was also examined. Complete contact of tongue-tip in the alveolar part of individual artificial EPG plate were shown at 0.3, 0.2, and 0.1 sec before complete tongue-palatal contact in the controls, although incomplete contact in the alveolar part were shown at 0.3 sec in mandibular prognathism patients. Whole total of tongue-palatal contact at 0.3 and 0.2 sec before complete tongue-palatal contact was significantly lower in the patients before surgery than in the controls (p<0.05). However, these values increased after surgery. The duration of oral and pharyngeal phase was significantly longer in the patients before surgery than in the controls and the patients after surgery (p<0.01). This study demonstrated that the tongue-palatal contact pattern improved and the duration of oral and pharyngeal phase was shortened in mandibular prognathism patients during swallowing after orthognathic surgery. It is suggested that changes in maxillofacial morphology by orthognathic surgery can induce normal tongue movement during swallowing. (The data underlying this study have been uploaded to figshare and are accessible using the following DOI: https://doi.org/10.6084/m9.figshare.14101616.v1).

Effects of hyperbaric oxygen treatment on calvarial bone regeneration in young and adult mice.

OBJECTIVE: The present study aimed to investigate the effects of hyperbaric oxygen (HBO) treatment on calvarial bone regeneration in young and adult mice. METHODS: Calvarial defects of 6.0 mm diameter were created in sixteen 3-week (young) and sixteen 32-week old (adult) mice. The mice were divided into two groups of eight animals each (HBO-treated and control). The 90-min HBO treatment at 2.5 absolute atmospheric pressure and 100 % oxygen was performed for five days a week for 12 weeks. After 2-weeks from the operation, micro-computerized tomography and video microscopy were used to evaluate the regenerated bone volume and microcirculation every two weeks. The protein concentrations of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in exudates of the calvarial tissue field were measured at 1, 2, 3, and 4 weeks after surgery. After 12 weeks, histochemical examination of regenerated calvarial bone was conducted. RESULTS: Regenerated bone was formed earlier in young mice than in adult mice treated with HBO. HBO stimulates angiogenesis in the periosteum around regenerated bone area in both young and adult mice at 2 weeks. VEGF concentrations in the calvarial tissue field were lower in the HBO group than in the control 1 week after operation, although bFGF were higher till the 2nd week in the HBO group than in the control. CONCLUSIONS: HBO accelerates bone regeneration earlier in young mice than in adult mice. In the HBO-treated group, bFGF expression was promoted at an early stage, although the expression of VEGF was inhibited.

Effect of continuous compressive force on the expression of RANKL, OPG, and VEGF in osteocytes.

The present study aimed to investigate the effect of a compressive force (CF) on the expression of receptor activator of nuclear factor kappa-B ligand (RANKL), osteoprotegerin (OPG), and vascular endothelial growth factor (VEGF) in murine osteocytes (MLO-Y4) as well as animal study. After application of a CF for 1, 3, 6, and 12 h, gene and protein expression of RANKL, OPG, and VEGF in MLO-Y4 cells were determined by real-time PCR and enzyme-linked immunosorbent assay (ELISA). Furthermore, the effect of a stretch-activated (S-A) channel was examined by gadolinium (Gd3+) administration. In an animal experiment, the expression of these factors in osteocytes of alveolar bone was examined after experimental tooth movement in rats. After CF application, significant increases in RANKL, VEGF and RANKL/OPG ratio were shown. The upregulated gene and protein levels of these factors were reduced by Gd3+ administration. After tooth movement, upregulated RANKL and VEGF were imunohistochemically shown in osteocytes of alveolar bone. These findings suggest that CF application on osteocytes elevates expression of osteoclast-inducing factor and angiogenesis factor in vivo and vitro.

Correction of skeletal class II severe open bite with temporomandibular joint disorder treated by miniscrew anchorage and molar extraction: a case report.

BACKGROUND: Little information is available on the treatment of open bite with temporomandibular joint disorder by intrusion of molars using miniscrews. CASE PRESENTATION: This case report describes a 42-year-old Japanese woman with a skeletal class II severe anterior open bite and temporomandibular joint disorder. The pretreatment magnetic resonance imaging of both temporomandibular joints revealed osteoarthritis and anterior disc displacement without reduction in both temporomandibular joints. A stabilization splint was used before orthodontic treatment and bilateral upper and lower premolars were extracted. Miniscrews were inserted into the palatal region to intrude the maxillary molars and avoid loss of anchorage. The maxillary left first molar was also extracted to improve the molar relationship and the dental midline. Normal overjet and overbite with Angle class I molar relationship were achieved, and the upper and lower midlines coincided. Our patient's teeth continued to be stable and her temporomandibular joint was asymptomatic after a retention period of 2 years. CONCLUSIONS: Intrusion of molars by miniscrews is available for skeletal class II severe open bite.

Acetaminophen reduces apical root resorption during orthodontic tooth movement in rats.

OBJECTIVE: The present study aimed to investigate the inhibitory effect of acetaminophen on apical root resorption during orthodontic tooth movement by controlling inflammation in the periodontal ligament and apical pulp tissue. METHODS: Human periodontal ligament and pulp cells were subjected to 10 kPa of cyclic tensile force (CTF) in a Flexcell Strain Unit for 48 h. Then, 10 and 100 µM acetaminophen were added to the culture medium, and the expression of interleukin (IL)-1B, receptor activator of nuclear factor kappa-B ligand (RANKL), tumor necrosis factor (TNF)α, and colony stimulating factor 1 (CSF1) were evaluated. In an animal experiment, the upper first molars of 7-week-old rats were moved mesially by applying 10 g of orthodontic force. After 30 days of force application, the effects of acetaminophen on apical root resorption were examined. RESULTS: In both the periodontal ligament and pulp cells, the expression levels of IL-1B, TNFα, RANKL, and CSF1 were significantly higher in the CTF-treated group than in the control group. However, the expression levels of these factors were decreased by acetaminophen administration. High expression of IL-1B, TNFα, RANKL, and CSF1 at the root apex were also detected immunohistochemically in rats after tooth movement, but were decreased by acetaminophen administration. In addition, the number of odontoclasts and the amount of apical root resorption were significantly decreased in the acetaminophen group. Importantly, no significant difference in tooth movement was observed between the acetaminophen and control groups. CONCLUSIONS: These results suggest that acetaminophen can reduce severe root resorption in the apex area without disturbing orthodontic tooth movement.