Changes in masticatory performance during the retention period following 4-premolar extraction and non-extraction orthodontic treatment.

OBJECTIVES: To evaluate changes in masticatory performance (MP) during the retention period after extraction and non-extraction treatment and compare it with MP in individuals with normal occlusion. MATERIALS AND METHODS: Adult patients who had completed orthodontic fixed appliance treatment comprised the extraction and non-extraction treatment groups, and those with normal occlusion comprised the control group. Their mixing ability (MA), maximum bite force (MBF), and occlusal contact area (OCA) were recorded immediately after the fixed appliance was removed and at 1 month, 6 months, and 1 year post-treatment. The MA was measured via the two-color chewing gum MA test using ViewGum software, and the MBF and OCA were measured using Dental Prescale II system. RESULTS: MA immediately after orthodontic treatment was lower than that in the normal group but showed a time-dependent gradual increase during a 1-year retention period (P < 0.01). The MA at 1 month post-treatment was not significantly different between the three groups (P > 0.05). The MA revealed a significant correlation with the MBF and OCA (P < 0.01). CONCLUSIONS: The MP immediately after orthodontic treatment was lower than that in the normal group but increased gradually, with levels comparable to those of the normal occlusion group at 1 month post-treatment. Further, extraction did not affect the recovery of the MP after orthodontic treatment. CLINICAL RELEVANCE: No other study has evaluated the changes in MP during the retention period after orthodontic treatment. The findings show that compared with MBF and OCA, the patients' MP improved faster to levels found in normal occlusion.

The Protective Effects of Botulinum Toxin A Against Flap Necrosis After Perforator Twisting and Its Underlying Molecular Mechanism in a Rat Model.

PURPOSE: The purpose of this study was to examine our hypotheses that botulinum toxin A (BoTA) protect necrosis of perforator flap from perforator twisting. METHODS: Twenty-four rats were randomly divided into 2 groups. Twelve International Units of BoTA versus 1.2 mL normal saline was injected subdermally 3 days before flap elevation. In each group, bilateral before deep inferior epigastric perforator (DIEP) flaps, 5 × 3 cm in size, were created. The right and left (180 and 360 degrees of perforator twisting) DIEP flaps were separated. At 1 and 3 days postoperatively, skin above the perforator of the DIEP flaps was harvested to examine the degrees of gene expressions. Final survival percentage of flap and histology were assessed at postoperative day 5. RESULTS: The survival percentage of flap was significantly higher in the BoTA group than in the control group at both DIEP flaps after 180 and 360 degrees of perforator twisting at postoperative day 5 (95.23 ± 2.85% vs 91.00 ± 3.77%; P = 0.021 and 91.59 ± 2.87% vs 30.03 ± 6.91%; P < 0.001, respectively).Higher fibroblast density, enhanced epithelial necrosis, and inflammation were noted in the control group than in the BoTA group. In 180 degrees of perforator twisting group, BoTA may augment angiogenesis possibly via nuclear factor-κB-induced destabilization and the nuclear factor-κB/hypoxia-inducible factor 1-α/vascular endothelial growth factor pathway, whereas in the 360 degrees of perforator twisting group, the mechanistic target of rapamycin/hypoxia-inducible factor 1-α/vascular endothelial growth factor pathway may participate in BoTA-induced effective angiogenesis. CONCLUSIONS: We demonstrated that pretreatment with BoTA protects perforator flap caused by perforator at the pathological and molecular level using an experimental rat model.

Presurgical Botulinum Toxin A Treatment Increases Angiogenesis by Hypoxia-Inducible Factor-1α/Vascular Endothelial Growth Factor and Subsequent Superiorly Based Transverse Rectus Abdominis Myocutaneous Flap Survival in a Rat Model.

To date, there have been several experimental studies to assess tissue viability of transverse rectus abdominis myocutaneous (TRAM) flaps. Botulinum toxin A (BoTA) has gained popularity in many clinical fields, for a variety of therapeutic and aesthetic purposes. In addition, there have been reports regarding the positive effect of BoTA on flap survival by various mechanisms. In this study, we hypothesized that pretreatment with BoTA could augment the survival of TRAM flaps via increased hypoxia-inducible factor (HIF)1α/vascular endothelial growth factor (VEGF)-dependent angiogenesis.Twenty-four Sprague-Dawley rats were randomly divided into 2 groups: a control group and a BoTA group. Five days before superiorly based TRAM flap elevation, the BoTA group was pretreated with BoTA, whereas the control group was pretreated with normal saline. Gross flap survival rates were assessed, and quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) and Western blotting were performed for the evaluation of angiogenesis-related factors (CD34, HIF-1α, and VEGF).In the BoTA group, the gross flap survival rate was significantly higher than that in the control group on both ipsilateral (92.78.3 ± 5.05% vs 86.8 ± 3.88%, P = 0.009) and contralateral (91.57 ± 5.79% vs 74.28 ± 11.83%, P < 0.001) sides.The relative mRNA expression of CD34 and VEGF was significantly higher in the BoTA group than that in the control group in every zone, whereas the relative mRNA expression of HIF-1α was significantly higher in the BoTA group than that in the control group on contralateral sides. The relative protein expression of CD34, VEGF, and HIF-1α was significantly higher in the BoTA group than that in the control group in every zone.In conclusion, we demonstrate that presurgical BoTA treatment might increase angiogenesis by HIF-1α/VEGF, subsequently increase superiorly based TRAM flap survival in a rat model.

Bilirubin provides perforator flap protection from ischaemia-reperfusion injury in a rat model: a preliminary result.

The use of bilirubin, a well-known and powerful antioxidant, has gained popularity in recent years because of its role in the prevention of ischaemic heart disease in patients with Gilbert's syndrome. We investigate the effects of bilirubin on ischaemia-reperfusion (I/R) injury using a rat perforator flap model. Forty-eight rats were randomly divided into two groups: experimental (bilirubin) group (n = 24) and control group (n = 24). In each group, elevated bilateral deep inferior epigastric perforator (DIEP) flaps were created. The right (no ischaemia side) and left (ischaemia side) DIEP flaps were separated according to the presence of ischaemia induction. Ischaemia was induced in anaesthetised rats by perforator clamping for 15 or 30 minutes. After surgery, the flap survival was assessed daily on postoperative days 0 to 5, and overall histological changes of DIEP flaps above the perforator were analysed at postoperative day 5. The flap survival rate in the bilirubin group was significantly higher than that in the control group at the ischaemia side following perforator clamping for 15 or 30 minutes (93·42 ± 4·48% versus 89·63 ± 3·98%, P = 0·002; and 83·96 ± 4·23% versus 36·46 ± 6·38%, P < 0·001, respectively). The difference in flap survival between the two groups was the most prominent on the ischaemic side following 30 minutes of perforator clamping. From a morphologic perspective, pre-treatment with bilirubin was found to alleviate perforator flap necrosis caused by I/R injury in this experimental rat model.

Single-tube nested PCR assay for the detection of avian botulism in cecal contents of chickens.

This paper describes a novel diagnostic method for the detection of avian botulism caused by Clostridium botulinum type C and C/D, using single-tube nested PCR assay. This assay was developed to overcome the disadvantages of bioassays used in experiments with mice. Three primer pairs including an antisense primer were designed to target the N-terminal of the toxin gene from C. botulinum types C and C/D. The specificity of the PCR assay was confirmed by using 33 bacterial strains and chicken cecal contents from farms that experienced botulism outbreaks. The detection limit for purified DNA was 1.1 fg/µl, and for bacterial spores was 4.3 spores/200 mg of cecal contents. While checking for specificity of the PCR assay, the reactions with the templates form C. botulinum type C and C/D which were tested became positive, but the rest of the reactions turned negative. However, the results for all clinical samples (n = 8) were positive. The PCR assay results for cecal samples obtained from 300 healthy chickens (150 Korean native chickens and 150 broilers) were all negative. This assay is rapid and straightforward and evades ethical issues associated with mouse bioassay. Moreover, it is more economical than real-time PCR.