Effects of a mandibular advancement device on genioglossus in obstructive sleep apnoea hypopnea syndrome.

OBJECTIVE: To investigate effects of mandibular advancement device (MAD) therapy for obstructive sleep apnoea hypopnea syndrome (OSAHS) on the genioglossus contractile properties and fibre-type distribution. MATERIALS AND METHODS: Thirty 6-month old male New Zealand white rabbits were randomised into three groups: OSAHS, MAD, and controls. Rabbits in Group OSAHS and Group MAD were established as OSAHS models by injection, at a dose of 2 ml hydrophilic polyacrylamide gel, via the submucous muscular layer of soft palate. Spiral computed tomography (CT) showed a significant reduced retropalatal upper airway, and apnoeas happened with an increase of Apnea Hypopnea Index (AHI) and a decrease of blood oxygen saturation during polysomnography (PSG), which indicated the OSAHS model developed successfully. OSAHS rabbits in Group MAD were fitted with a MAD made from self-curing composite resin, at 30 degrees to the upper incisors, and the mandible was guided forward 3 to 4mm. Further, spiral CT and PSG suggested MAD was effective. Rabbits in 3 groups were induced to sleep for 4-6 hours per day for 8 weeks, after which the genioglossus was removed, mounted in a tissue bath, and stimulated through platinum electrodes; maximal twitch tension, contraction time, half-relaxation time, force-frequency relationship, and fatigability were recorded. The percentage of Type I and Type II fibres was quantified. RESULTS: The fatigability and percentage of Type II fibres of genioglossus increased in Group OSAHS compared with controls; this abnormality was corrected by MAD. CONCLUSION: MAD therapy for OSAHS could prevent genioglossus fatigue and abnormal fibre-type distribution of genioglossus in OSAHS.

Preclinical Evaluation of a Novel Sirolimus-Eluting Iron Bioresorbable Coronary Scaffold in Porcine Coronary Artery at 6 Months.

OBJECTIVES: The aim of this study was to investigate the operability, 6-month efficacy, and safety of the novel sirolimus-eluting iron bioresorbable coronary scaffold (IBS) system compared with a cobalt-chromium everolimus-eluting stent (EES) (XIENCE Prime stent) in porcine coronary arteries. BACKGROUND: Bioresorbable scaffolds have been considered the fourth revolution in percutaneous coronary intervention. However, the first-generation bioresorbable scaffold showed suboptimal results. METHODS: Forty-eight IBS and 48 EES were randomly implanted into nonatherosclerotic swine. The operability, efficacy, and safety of the IBS and EES were evaluated using coronary angiography, optical coherence tomography, micro-computed tomography, scanning electron microscopy, and histopathologic evaluation at 7, 14, 28, 90, and 180 days after implantation. RESULTS: The operability of the ultrathin IBS (∼70 µm) was comparable with that of the EES, except for its visibility. There was no statistically significant difference in area stenosis between the IBS and EES from 28 to 180 days. The IBS maintained its integrity up to 90 days without corrosion, while corrosion was observed in a few struts in 2 of 10 IBS at 180 days. The percentage of endothelialization of IBS was higher than that of XIENCE Prime stents within 14 days after implantation. The fibrin score was higher in the IBS group at 28 days but comparable with the EES group at 90 and 180 days. No scaffold or stent thrombosis was seen in either group. No abnormal histopathologic changes in scaffolded or stented vessel segments and 5 main remote organs were observed in either group. CONCLUSIONS: Preclinical results suggest that the novel IBS has comparable operability, mid-term efficacy, and safety with the EES, and its corrosion profile in porcine coronary arteries is reasonable, which could support initial clinical study of the IBS.

The effects of increasing occlusal vertical dimension on the deep masseter of rat at different ages.

OBJECTIVE: To investigate the influence of increasing the occlusal vertical dimension (iOVD) on the fibre-type distribution and ultrastructure of deep masseter of rat at different ages. DESIGN: A total of forty-eight male Wistar rats were divided into two groups according to age: 'teenage' group (n=24, 1.5 months) and 'young adult' group (n=24, 8 months). Both the teenage and the young adult rats were then randomly divided into the control group (n=12) and the experimental group (n=12). The occlusal vertical dimensions of the rats in the experimental groups were increased by placing composite resin on all maxillary molars. The fibre-type distribution and ultrastructure of the deep masseter were subsequently observed on day 7 and day 14 after iOVD. RESULTS: In the teenage experimental group, the proportion of type IIa fibres increased, while the proportion of type IIb and type IIx fibres decreased by day 7 after iOVD (P<0.05). However, no significant fibre phenotype transformation was observed in the young adult experimental group until day 14 after iOVD. In addition, the proportion of type IIa in the teenage experimental group was higher than that of the young adult experimental group on day 7 and 14 (P<0.05). Under the transmission electron microscope, muscle fibre reconstruction and the compensatory increase in the number and volume of mitochondria appeared earlier in the teenage experimental group. The cellular traumatic reaction was less than that in the young adult experimental group. CONCLUSION: The teenage rat alters masseter muscle structure to a slower phenotype earlier and to a greater degree than that of the young adult rat when increasing the occlusal vertical dimension.

[Establishment of the craniofacial three-dimensional finite element models with the sutures defined alone].

OBJECTIVE: To develop a child craniofacial three-dimensional (3D) finite element model (FEM) with sutures defined alone. METHODS: The CT data for this study was developed from sequential computed tomography scan images taken at 0.625 mm intervals of an 8 years children skull. Data set was imported into Mimics 10.0 and processed with Geomagic 9.0, and exported as initial graphics exchange specification(IGES) files. The IGES files were then imported into Ansys 13.0 to set up two FEM with or without the median palatine suture being opened. The FEM contained nine craniofacial sutures and eight teeth which were defined alone.For simulating orthopedic maxillary protraction, three forces (F1-F2) were loaded on FEM.F1(1 N) was loaded at 1 cm above the geison. F2(1 N) was loaded at articular fossa of temporal bone. F3(2 N) was directed anteriorly and paralleled with occlusal plane near the canine. The stress distribution and the values distributed in each point gained in the two models were compared. RESULTS: Two craniofacial 3D FEM of the child were developed with the median palatine suture opened or not .With median palatine suture being opened or not, the two models showed the similar von Mises stresses (VMS). The distribution of the VMS was in the bridge of the nose and dextro-ala nasi.When the median palatine suture was opened, the max VMS value was 18916.00×10(-4) MPa which appeared in the nose point and the min VMS value was 1.61×10(-4) MPa which appeared in the maxillary central incisor point. At the same time, the max stress value at the direction Y was -3985.30×10(-4) MPa and appeared in the frontomaxillary suture point, and the min Y value was 0.08×10(-4) MPa which appeared in the maxillary central incisor point. When the median palatine suture was not opened, the max VMS value was 19 244.00×10(-4) MPa and appeared in the nose point. The min VMS value was 1.62×10(-4) MPa and appeared in the maxillary central incisor point. At the same time, the max stress value at the direction Y was -4258.20×10(-4) MPa and appeared in the frontomaxillary suture point, and the min Y value was 0.08×10(-4) MPa which appeared in the maxillary central incisor point. CONCLUSIONS: To define the sutures as entities alone contributed to develop child craniofacial 3D FEM which consist nine sutures. There was tiny difference in stress distribution in both the VMS and in Y direction with the median palatine suture being opened or not.

[Effect of maxillary protraction with or without rapid palatal expansion in treating early skeletal Class III malocclusion].

OBJECTIVE: To evaluate the effectiveness of treatment with maxillary protraction with or without rapid palatal expansion (RPE) for skeletal Class III malocclusion in mixed dentition. METHODS: A total of 31 children with Class III malocclusion in mixed dentition were selected, and 15 (group A) received maxillary protraction treatment with RPE, the other 16 (group B) received maxillary protraction without RPE. Cephalometric films were taken before and after treatment, and traditional and Pancherz analysis were used. RESULTS: The average duration of treatment was 10.14 months in group A and 9.77 months in group B respectively (P>0.05). According to Pancherz analysis, maxillary basal bone moved forwards by 2.99 mm in group A and 3.33 mm in group B respectively (P>0.05), mandibular basal bone moved backwards by 0.07 mm in group A, while forwards by 0.80 mm in group B (P>0.05), the overjet increased by 4.51 mm in group A and 6.37 mm in group B respectively (P<0.05), and the molar relationship improved by 4.97 mm in group A and 4.73 mm in group B respectively (P>0.05). The effects were clinically satisfactory in the both groups. Lower molar moved forwards by 1.18 mm in basal bone in group A, while backwards by 1.20 mm in group B (P<0.05). Traditional cephalometric analysis showed no statistic differences between the two groups except that upper incisior showed greater procline in group B than in group A (P<0.05). CONCLUSION: The study shows that maxillary protraction treatment, with or without RPE, is clinically satisfactory to correct early skeletal Class III malocclusion.