Investigation of Gpx1 in chondrogenesis and its role on redox regulation in chondrocytes

Orthodontics deals with the correction of skeletal anomalies of the face occurring in the form of jaw discrepancies. There is an abundance of findings in the literature that the development and growth of the cranial base influence facial shape and jaw discrepancies. Cranial base develops by the mechanism of endochondral ossification taking place at its midline axis, where all the synchondroses are located. Chondrogenesis is the initial and indispensable part of endochondral bone formation. In the light of evidence underlying the need of reactive oxygen species in the regulation of chondrogenesis, this study aimed to investigate the ubiquitously present antioxidant enzyme Gpx1 and its contribution to redox regulation in chondrogenesis. Provided that the levels of oxidative stress were previously found to fluctuate according to the differentiation stage of chondrocytes, the gene expression of Gpx1 was measured with quantitative RT-PCR during chondrogenic differentiation. For this purpose, the chondrogenic cell line ATDC5 was utilized and cultured for 21 days. The time points of measurements were on days 0, 2, 6, 10, 14, and 21. The chondrogenic differentiation of the utilized cell line was determined with the stains Alcian blue and Alizarin red, and with the gene expression of chondrogenic biological markers Col2a1 and Col10a1. The present results suggest that the expression of Gpx1 is not of constitutive nature during chondrogenic differentiation. Taking this as a starting point, the next step was to quantitatively assess the distribution pattern of Gpx1 at the different differentiation stages of chondrogenesis. To examine this, the spheno-occipital synchondrosis from eight newborn male Wistar rats was isolated and samples were processed for formaldehyde-fixed paraffin-embedded immunohistochemistry. Photographs of the immunostained sections were analysed by two independent observers and a five-grade semiquantitative scale was used to assess Gpx1 immunoreactivity at the synchondrosis. The present findings show that Gpx1 is expressed the most at the proliferative differentiation stage and the lowest at the hypertrophic differentiation stage. Existing literature reports that an increase in oxidative levels is needed for inhibition of proliferation and initiation of hypertrophy. Further, chondrocytes at the hypertrophic stage have the highest levels of ROS compared to other differentiation stages. In this context, the present results implied that Gpx1 is involved in redox regulation in chondrogenesis. To pursue this further, the expression of Gpx1 was manipulated in ATDC5 chondrogenic cells and cells were then exposed to exogenous H2O2. The manipulation of Gpx1 expression included overexpression and silencing. A control group was also included. The apoptotic percentage of cells was measured flow cytometrically with FITC-labelled Annexin V in conjunction with PI dye. The highest apoptotic percentage was observed in Gpx1-depleted chondrocytes, followed by the control group. The lowest apoptotic percentage was presented in Gpx1-overexpressing cells. These results indicate that Gpx1 possesses an active role on the cellular enzymatic antioxidant system of chondrocytes and can regulate the cellular redox state by H2O2 scavenging. Furthermore, its presence in chondrocytes can prevent H2O2-induced apoptosis. The contribution of cranial base growth to craniofacial morphology continues until adulthood, since spheno-occipital synchondrosis is the last of the synchondroses to ossify and is active until then. This study localizes the expression of Gpx1 at the spheno-occipital synchondrosis and documents the role of Gpx1 as a redox regulator in chondrocytes

Long-term stability after high-pull headgear combined with fixed appliances: A retrospective cohort study of growing class II patients

BACKGROUND High-pull headgear with fixed appliances is a common therapeutic plan in class II growing individuals, especially in those with a tendency to hyperdivergence. The stability of this approach has not been adequately assessed in the long-term. The aim of this retrospective study was to assess that long-term stability by means of lateral cephalograms. Seventy-four consecutive patients were included and examined at three time-points: pre-treatment (T1), end of treatment (T2), and at least five years post-treatment (T3). RESULTS The average initial age of the sample was 9.3 years (standard deviation, SD: 1.6). At T1, the mean ANB was 5.1 degrees (SD: 1.6), the mean SN-PP 5.6 (SD: 3.0) and the mean MP-PP 28.7 degrees (SD: 4.0). The median follow-up time was 8.6 years with an interquartile range of 2.7. A statistically significant, but of small magnitude increase in the SNA angle was noted at T3 compared to T2 after adjusting for the pre-treatment SNA value (mean difference (MD): 0.75; 95% CI: 0.34, 1.15; P<0.001). The inclination of the palatal plane appeared stable in the post-treatment period, while the MP-PP angle showed scarce evidence of decrease during the post-treatment period after adjusting for sex, pre-treatment SNA and SN-PP angles (MD: -2.29; 95% CI: -2.85, -1.74; P<0.001). CONCLUSIONS The sagittal position of the maxilla and the inclination of the palatal plane appeared to be stable after treatment with high-pull headgear and fixed appliances in the long-term. Continuous mandibular growth, both sagittaly and vertically, contributed to the stability of class II correction

Effect of four premolar extractions on the vertical dimension of the face : A retrospective cephalometric study

PURPOSE Adequate control of the vertical dimension is of great importance in orthodontic treatment. Although existing evidence is very limited, extraction of four premolars is thought to contribute towards improved control of anterior facial height compared with non-extraction treatment protocols. Thus, the aim of this retrospective cohort study was to compare the effect of fixed-appliance treatment with extraction of four premolars to non-extraction treatment on the skeletal vertical dimension. METHODS A consecutive sample of 76 children with skeletal hyperdivergence (49% male; mean age 11.9 years) was divided into two groups for treatment with either non-extraction (n = 31) or extraction of four premolars (n = 45). Baseline characteristics were comparable: overjet 5.1 ± 2.5 mm, overbite 2.4 ± 1.9 mm, ANB angle 4.6 ± 2.3°, and SN-ML angle 40.2 ± 3.5°. Patients were treated with standard edgewise fixed appliances with closing loops/sliding mechanics. Vertical skeletal and dental outcomes were measured on lateral cephalograms before and after treatment. Data were analyzed with linear regression at 5%. RESULTS Compared to non-extraction treatment, treatment with premolar extractions had no significant effect on the SN-ML angle (difference (Δ) = 0.07°; 95% confidence interval -0.90 to 1.01°; P = 0.88). Statistically significant changes between the extraction and non-extraction groups were only found for the parameters SNA (Δ -1.47°; P = 0.003), ANB (Δ -1.17°; P = 0.004), SN-OP (Δ -1.48°; P = 0.04), and L1-ML (Δ -6.39°; P < 0.001). CONCLUSION Orthodontic treatment of children with skeletal hyperdivergence using systematic extraction of four premolars had minimal effects on the vertical facial dimension compared to non-extraction treatment

Covariance patterns between ramus morphology and the rest of the face: A geometric morphometric study

OBJECTIVE The growth and development of the mandible strongly depend on modeling changes occurring at its ramus. Here, we investigated covariance patterns between the morphology of the ramus and the rest of the face. METHODS Lateral cephalograms of 159 adults (55 males and 104 females) with no history of orthodontic treatment were collected. Geometric morphometrics with sliding semi-landmarks was used. The covariance between the ramus and face was investigated using a two-block partial least squares analysis (PLS). Sexual dimorphism and allometry were also assessed. RESULTS Differences in the divergence of the face and anteroposterior relationship of the jaws accounted for 24.1% and 21.6% of shape variation in the sample, respectively. Shape variation was greater in the sagittal plane for males than for females (30.7% vs. 17.4%), whereas variation in the vertical plane was similar for both sexes (23.7% for males and 25.4% for females). Size-related allometric differences between the sexes accounted for the shape variation to a maximum of 6% regarding the face. Regarding the covariation between the shapes of the ramus and the rest of the face, wider and shorter rami were associated with a decreased lower anterior facial height as well as a prognathic mandible and maxilla (PLS 1, 45.5% of the covariance). Additionally, a more posteriorly inclined ramus in the lower region was correlated with a Class II pattern and flat mandibular plane. CONCLUSIONS The width, height, and inclination of the ramus were correlated with facial shape changes in the vertical and sagittal planes

The Effect of Leveling the Curve of Spee on the Inclination of Mandibular Incisors: A Retrospective Cephalometric Study

PURPOSE To assess mandibular incisor inclination after leveling the curve of Spee (CoS) in patients treated with fixed appliances. MATERIALS AND METHODS This was a retrospective study, which included 80 consecutive patients with a mild CoS treated without extraction but with various biomechanical approaches. The depth of CoS was digitally measured on scanned plaster casts and mandibular incisor inclination was assessed with lateral cephalograms pre- and posttreatment. Patients were treated with 0.018"-slot edgewise fixed appliances and cinched back wires. Data were analyzed using linear regression modeling at 5%. RESULTS A total of 80 patients (40% female; mean age 13.8 years) were included with mean ANB = 4.4 ± 1.9°, mean SN/ML = 31.7 ± 4.7°, mean L1/ML = 95.0 ± 7.7°, and a mean depth of CoS = 1.1 ± 0.4 mm. The depth of CoS was leveled by -0.85 ± 0.39 mm to a post-treatment median of 0.18 mm (interquartile range = 0.09 to 0.35 mm). A small mandibular incisor proclination was observed through treatment (2.49 ± 9.1°), but this was not associated with the reduction in the depth of CoS (p > 0.05) and no statistically significant modifying effect from the different treatment mechanics was observed. CONCLUSION Under the limitations of this study, leveling a mild CoS was not associated with mandibular incisor proclination during fixed-appliance treatment

Bias from historical control groups used in orthodontic research: a meta-epidemiological study

AIM The validity of meta-analysis is dependent upon the quality of included studies. Here, we investigated whether the design of untreated control groups (i.e. source and timing of data collection) influences the results of clinical trials in orthodontic research. MATERIALS AND METHODS This meta-epidemiological study used unrestricted literature searching for meta-analyses in orthodontics including clinical trials with untreated control groups. Differences in standardized mean differences (ΔSMD) and their 95% confidence intervals (CIs) were calculated according to the untreated control group through multivariable random-effects meta-regression controlling for nature of the interventional group and study sample size. Effects were pooled with random-effects synthesis, followed by mixed-effect subgroup and sensitivity analyses. RESULTS Studies with historical control groups reported deflated treatment effects compared to studies with concurrent control groups (13 meta-analyses; ΔSMD = -0.31; 95% CI = -0.53, -0.10; P = 0.004). Significant differences were found according to the type of historical control group (based either on growth study or clinical archive; 11 meta-analyses; ΔSMD = 0.40; 95% CI = 0.21, 0.59; P < 0.001). CONCLUSIONS The use of historical control groups in orthodontic clinical research was associated with deflation of treatment effects, which was independent from whether the interventional group was prospective or retrospective and from the study's sample size. Caution is warranted when interpreting clinical studies with historical untreated control groups or when interpreting systematic reviews that include such studies

Duration of orthodontic treatment with fixed appliances in adolescents and adults: a systematic review with meta-analysis

OBJECTIVES Adults with fixed orthodontic appliances are increasing nowadays. Compared with adolescents, adults present biological differences that might influence treatment duration. Therefore, the aim of the study was to compare duration of treatment with fixed appliances between adults and adolescents. MATERIALS AND METHODS Eight databases were searched up to September 2019 for randomized and non-randomized clinical studies comparing treatment duration with fixed appliances in adolescents and adult patients. After duplicate study selection, data extraction, and risk of bias assessment with the Cochrane ROBINS-I tool, random effects meta-analyses of mean differences (MD) and their 95% confidence intervals (CIs) were performed, followed by assessment of the quality of evidence with GRADE. RESULTS A total of 11 unique studies (one prospective and 10 retrospective non-randomized) with 2969 adolescents and 1380 adult patients were finally included. Meta-analysis of 7 studies found no significant difference in the duration of comprehensive treatment with fixed appliances (MD = - 0.8 month; 95% CI = - 4.2 to 2.6 months; P = 0.65; I$^{2}$ = 92%) between adults and adolescents. Similarly, both distalization of upper first molars with skeletal anchorage for class II correction and the retraction of canines into the premolar extraction spaces lasted similarly long among adults and adolescents. On the other hand, alignment of palatally displaced canines lasted considerably longer in adults compared to adolescents (1 study; MD = 3.8 months; 95% CI = 1.4 to 6.2 months; P = 0.002). The quality of evidence for the meta-analysis was low due to the inclusion of non-randomized studies with considerable risk of bias. CONCLUSIONS While existing evidence does not indicate a difference in the overall duration of treatment with fixed appliances between adults and adolescents, the alignment of palatally displaced canines lasted significantly longer in adults. However, our confidence in these estimates is low due to the risk of bias in the included studies. TRIAL REGISTRATION PROSPERO: ( CRD42019148169 )

Effect of Orthopedic Treatment for Class III Malocclusion on Upper Airways: A Systematic Review and Meta-Analysis

The aim of this systematic review is to compare the effect on the upper airways of orthopedic treatment for skeletal Class III malocclusion with untreated controls. Nine databases were searched up to August 2020 for randomized or nonrandomized clinical trials comparing orthopedic Class III treatment (facemask or chin-cup) to untreated Class III patients. After duplicate study selection, data extraction, and risk of bias assessment (Risk Of Bias In Non-randomized Studies - of Interventions [ROBINS-I]), random-effects meta-analyses of Mean Differences (MDs)/Standardized Mean Differences (SMD) and 95% Confidence Intervals (CIs) were performed, followed by the Grading of Recommendations Assessment, Development and Evaluation assessment evidence-quality. A total of 10 papers (9 unique nonrandomized studies) with 466 patients (42.7% male; average age 9.1 years) were finally included. Limited evidence indicated that compared to normal growth, maxillary protraction with facemask was associated with increases in total airway area (n = 1; MD = 222.9 mm$^{2}$; 95% CI = 14.0-431.7 mm$^{2}$), total nasopharyngeal area (n = 4; SMD = 1.6; 95% CI = 1.2-2.0), and individual airway dimensions (upper-airway MD = 2.5 mm; lower-airway MD = 2.1 mm; upper-pharynx MD = 1.6 mm; lower-pharynx MD = 1.0 mm; all n = 6). Subgroup/meta-regression analyses did not find any significant effect-modifiers, while the results were retained 2-5 years postretention. Our confidence in these estimates was, however, very low, due to the inclusion of nonrandomized studies with methodological issues. Limited data from 2 chin-cup studies indicated smaller benefits on airway dimensions. Existing evidence from controlled clinical studies on humans indicates that maxillary protraction for skeletal Class III treatment might be associated with increased airway dimensions, which are, however, mostly minor in magnitude