Colour stabilities of three types of orthodontic clear aligners exposed to staining agents

The aim of this study was to evaluate and compare the colour stabilities of three types of orthodontic clear aligners exposed to staining agents in vitro. Sixty clear orthodontic aligners produced by three manufacturers （Invisalign, Angelalign, and Smartee） were immersed in three staining solutions （coffee, black tea, and red wine） and one control solution （distilled water）. After 12-h and 7-day immersions, the aligners were washed in an ultrasonic cleaner and measured with a colourimeter. The colour changes （△E＊） were calculated on the basis of the Commission Internationale de I＇Eclairage L＊a＊b＊ colour system （CIE L＊a＊b＊）, and the results were then converted into National Bureau of Standards （NBS） units. Fourier transformation infrared （FT-IR） spectroscopy and scanning electron microscopy （SEM） were conducted to observe the molecular and morphologic alterations to the aligner surfaces, respectively. The three types of aligners exhibited slight colour changes after 12 h of staining, with the exception of the Invisalign aligners stained with coffee. The Invisalign aligners exhibited significantly higher AE＊ values （ranging from 0.30 to 27.81） than those of the Angelalign and Smartee aligners （AE＊ values ranging from 0.33 to 1.89 and 0.32 to 1.61, respectively, P〈O.05）. IFT-IR analysis confirmed that the polymer-based structure of aligners did not exhibit significant chemical differences before and after the immersions. The SEM results revealed different surface alterations to the three types of aligner materials after the 7-day staining. The three types of aesthetic orthodontic appliances exhibited colour stability after the 12-h immersion, with the exception of the Invisalign aligners stained by coffee. The Invisalign aligners were more prone than the Angelalign and Smartee aligners to pigmentation. Aligner materials may be improved by considering aesthetic colour stability properties.

The role of microRNAs in bone remodeling

Bone remodeling is balanced by bone formation and bone resorption as well as by alterations in the quantities and functions of seed cells, leading to either the maintenance or deterioration of bone status. The existing evidence indicates that micro RNAs（mi RNAs）, known as a family of short non-coding RNAs, are the key post-transcriptional repressors of gene expression,and growing numbers of novel mi RNAs have been verified to play vital roles in the regulation of osteogenesis, osteoclastogenesis,and adipogenesis, revealing how they interact with signaling molecules to control these processes. This review summarizes the current knowledge of the roles of mi RNAs in regulating bone remodeling as well as novel applications for mi RNAs in biomaterials for therapeutic purposes.

Reliability assessment and correlation analysis of evaluating orthodontic treatment outcome in Chinese patients

This study aimed to assess the reliability of experienced Chinese orthodontists in evaluating treatment outcome and to determine the correlations between three diagnostic information sources. Sixty-nine experienced Chinese orthodontic specialists each evaluated the outcome of orthodontic treatment of 108 Chinese patients. Three different information sources： study casts （SC）, lateral cephalometric X-ray images （LX） and facial photographs （PH） were generated at the end of treatment for 108 patients selected randomly from six orthodontic treatment centers throughout China. Six different assessments of treatment outcome were made by each orthodontist using data from the three information sources separately and in combination. Each assessment included both ranking and grading for each patient. The rankings of each of the 69 judges for the 108 patients were correlated with the rankings of each of the other judges yielding 13 873 Spearman rs values, ranging from -0.08 to ＋0.85. Of these, 90% were greater than 0.4, showing moderate-to-high consistency among the 69 orthodontists. In the combined evaluations, study casts were the most significant predictive component （R2=0.86, P〈0.000 1）, while the inclusion of lateral cephalometric films and facial photographs also contributed to a more comprehensive assessment （R2=0.96, P〈0.000 1）. Grading scores for SC＋LX and SC＋PH were highly significantly correlated with those for SC＋LX＋PH （r（SC＋LX）vs.（SC＋LX＋PH）=0.96, r（SC＋PH）vs.（SC＋LX＋PH）=0.97）, showing that either SC＋LX or SC＋PH is an excellent substitute for all three combined assessment,

Epigenetic regulation by long noncoding RNAs in osteo-/adipogenic differentiation of mesenchymal stromal cells and degenerative bone diseases

Bone is a complex tissue that undergoes constant remodeling to maintain homeostasis,which requires coordinated multilineage differentiation and proper proliferation of mesenchymal stromal cells(MSCs).Mounting evidence indicates that a disturbance of bone homeostasis can trigger degenerative bone diseases,including osteoporosis and osteoarthritis.In addition to conventional genetic modifications,epigenetic modifications(i.e.,DNA methylation,histone modifications,and the expression of noncoding RNAs)are considered to be contributing factors that affect bone homeostasis.Long noncoding RNAs(lncRNAs)were previously regarded as‘transcriptional noise’with no biological functions.However,substantial evidence suggests that lncRNAs have roles in the epigenetic regulation of biological processes in MSCs and related diseases.In this review,we summarized the interactions between lncRNAs and epigenetic modifiers associated with osteo-/adipogenic differentiation of MSCs and the pathogenesis of degenerative bone diseases and highlighted promising lncRNA-based diagnostic and therapeutic targets for bone diseases.

Successful Treatment of Postpeak Stage Patients with ClassⅡ Division 1 Malocclusion Using Non-extraction and Multiloop Edgewise Archwire Therapy: A Report on 16 Cases

Aim To determine cephalometrically the mechanism of the treatment effects of non-extraction and multiloop edgewise archwire （MEAW） technique on postpeak Class Ⅱ Division 1 patients. Methodology In this retrospective study, 16 postpeak Class Ⅱ Division 1 patients successfully corrected using a non-extraction and MEAW technique were cephalometrically evaluated and compared with 16 matched control subjects treated using an extraction technique. Using CorelDRAW software, standardized digital cephalograms preand post-active treatments were traced and a reference grid was set up. The superimpositions were based on the cranial base, the mandibular and the maxilla regions,and skeletal and dental changes were measured. Changes following treatment were evaluated using the paired-sample t-test. Student＇s t-test for unpaired samples was used to assess the differences in changes between the MEAW and the extraction control groups. Results The correction of the molar relationships comprised 54% skeletal change （mainly the advancement of the mandible） and 46% dental change. Correction of the anterior teeth relationships comprised 30% skeletal change and 70% dental change. Conclusion The MEAW technique can produce the desired vertical and sagittal movement of the tooth segment and then effectively stimulate mandibular advancement by utilizing the residual growth potential of the condyle.

Orthodontic retreatment of an adult woman with mandibular backward positioning and temporomandibular joint disorder:A case report

BACKGROUND The role of occlusal factors on the occurrence of temporomandibular joint disorders(TMDs)is still unclear and it is tricky for orthodontists to treat malocclusions in patients with TMDs.We report the case of the second orthodontic treatment of an adult female with Class II division 2 malocclusion associated with TMD.With the removal of anterior occlusal interference,TMD symptoms were alleviated and cone beam computed tomography(CBCT)images showed the bilateral condyles shifted forward.CASE SUMMARY This case report presented an orthodontic retreatment of an adult female with TMD and mandibular backward positioning based on CBCT examination and Joint Space Index(JSI)analysis.The left and right JSI values of-38.5 and-52.6 indicated that the position of bilateral condyles had posterior displacement.Ten years prior to this evaluation,she underwent orthodontic treatment resulting in the extraction of two upper premolars and one lower central incisor.The joint symptoms,including pain and sounds,were alleviated along with verified mandibular forward repositioning by extraction of another lower central incisor.CONCLUSION Mandibular backward positioning could be associated with TMD.JSI analysis based on CBCT is a convenient way to examine condylar positions quantitatively.