Animals ; Oocytes ; metabolism ; physiology ; Receptors, G-Protein-Coupled ; physiology ; Receptors, Purinergic P2X ; physiology ; Xenopus laevis

The bracketless invisible aligner technique has been considered as a new developed orthodontic technique since its appearance during the period of late 1990s. It is characterized with the advantages of more aesthetic, comfortable, simple, high-efficient and predictable compared with current traditional orthodontic techniques depending on brackets and wires for orthodontic tooth movements. There have been many opportunities for further development and clinical application for the technique with the developments of material sciences, computer software and hardware technology, rapid prototyping techniques, et al. Nevertheless, kinds of difficulties and challenges have been and should be met either at present or in the future for this relatively new technique which just occurred around 10 years ago. The histories, developments with opportunities and challenges and prospects of the technique will be reviewed and discussed in this paper.
Humans ; Orthodontic Appliances ; Tooth Movement Techniques

OBJECTIVETo observe the occlusal contacts in intercuspal position(ICP) in adolescent patients after orthodontic treatment.

METHODSFourteen adolescent patients after orthodontic treatment were selected as experimental group and 17 healthy adolescents and young adults with normal occlusion were selected as control group. The occlusal contact in ICP in the two groups were recorded with T-Scan II system and compared.

RESULTSWhen the total of force (TOF) were 1/10 TOFmax, 1/4 TOFmax, 1/2 TOFmax, 3/4 TOFmax and TOFmax, the number of occlusal contacts in the anterior segment in the experimental group were 1.5(1.0), 3.0(1.3), 4.5(3.3), 5.5(3.0), 5.5(3.3), which were significantly larger than that in control group [0.0(0.3), 0.0(0.6), 0.3(0.5), 0.3(1.0), 0.0(1.8), P < 0.05]. There were no significant difference in the area of occlusal contacts in the posterior segment between experimental group and control group (P > 0.05). The center of force (COF) in the experimental group located significantly more mesially than that in control group. The value of ICP contact time in experimental group was 0.192(0.141) s and no significant difference was found between experimental group and control group [0.163(0.200) s].

CONCLUSIONSAlthough the patients achieved normal occlusion after orthodontic treatment, their anterior teeth received more occlusal force than those in healthy adolescents and young adults with normal occlusion.

Adolescent ; Bite Force ; Case-Control Studies ; Dental Occlusion ; Humans ; Incisor ; Orthodontics ; Young Adult

OBJECTIVETo investigate the relationship between condyle movement and temporomandibular disorders (TMD) in patients with Class II division 1 malocclusion.

METHODSTwenty patients (from 11 to 12 years old) with Class II division 1 malocclusion before treatment were collected. Computer aided diagnosis axiograph (CADIAX) and magnetic resonance images (MRI) were used to analyze the condyle movement between disc displacement and normal groups.

RESULTSThe sensitive values were found in open/close process in patients with disc displacement: Y [Left: (0.32 +/- 0.10) mm, Right: (-0.91 +/- 0.49) mm ], Z [Left: (4.20 +/- 0.70) mm, Right: (3.44 +/- 0.21) mm], sagittal condylar inclination (SCI) [Left: (32.48 +/- 7.70) degrees , Right: (33.47 +/- 12.60) degrees ] and horizontal condylar inclination (TCI) [Left: (-2.60 +/- 2.02) degrees , R: (-9.23 +/- 5.58) degrees ], and those items showed significant difference between two groups.

CONCLUSIONSThe side shift of condyle movement in maximum open/close process might be the inducement of disc displacement. It was revealed that the changes in condyle movement could give useful information in early stage of functional treatment.

Child ; Diagnosis, Computer-Assisted ; instrumentation ; Female ; Humans ; Jaw Relation Record ; Male ; Malocclusion, Angle Class II ; complications ; physiopathology ; Mandibular Condyle ; pathology ; physiopathology ; Movement ; Temporomandibular Joint Disc ; pathology ; Temporomandibular Joint Disorders ; etiology ; pathology

OBJECTIVETo treat the patients with anterior spaces caused by periodontal diseases with aligners and evaluate the periodontal conditions before and after treatment.

METHODSSeven patients with anterior spaces ranged from 3.0 to 4.5 mm were randomly selected. All the patients were treated with aligner technique to close the spaces. Bleeding on probing (BOP) and probing depth (PD) were measured before treatment, 1 month, 3 months and 6 months after treatment. The CEJ-ABC distance was evaluated before treatment, 1 month, and 6 months after treatment.

RESULTSNo significant differences were found in periodontal evaluation and the CEJ-ABC distance between any two evaluated stages.

CONCLUSIONSThe aligners could be used in patients with anterior spaces caused by periodontal diseases. No periodontal tissue damages were found during the observation period.

Adult ; Diastema ; etiology ; therapy ; Female ; Humans ; Male ; Orthodontic Appliances ; Periodontal Diseases ; complications

OBJECTIVETo investigate the mechanical properties of Ni-Ti wires with direct electric resistance heat treatment (DERHT) method in three-point bending tests.

METHODSTwo superelastic Ni-Ti wires (wire A: Smart SE, wire B: SENTALLOY SE, 0.406 mm × 0.559 mm) and 2 heat-actived Ni-Ti wires (wire C: Smart SM, wire D: L&H TITAN, 0.406 mm × 0.559 mm) were selected. They were heat-treated using the DERHT method by a controlled electric current (6.36 A) applied for different period of time [0 (control), 1.0, 1.5, 2.0, 2.5 seconds). Then, a three-point bending test was performed under controlled temperature (37°C) to examine the relationships between the deflection and the load in the bending of wires.

RESULTSAfter DERHT treatment, the plateau in the force-deflection curve of superelastic Ni-Ti wires and heat-activated Ni-Ti wires were increased. When the wires were heated for 2.0 seconds and deflected to 1.5 mm, the loading force of A, B, C and D Ni-Ti wires increased from (3.85 ± 0.11), (3.62 ± 0.07), (3.28 ± 0.09), (2.91 ± 0.23) N to (4.33 ± 0.07), (4.07 ± 0.05), (4.52 ± 0.08), (3.27 ± 0.15) N respectively.

CONCLUSIONSDERHT method is very convenient for clinical use. It is possible to change the arch form and superelastic force of NiTi wires. The longer the heating time is, the more the superelastic characteristics of the wires are altered.

Dental Stress Analysis ; Elasticity ; Hot Temperature ; Materials Testing ; Nickel ; chemistry ; Orthodontic Wires ; Stress, Mechanical ; Titanium ; chemistry

OBJECTIVETo evaluate the stability of mini-screw implant during different healing periods in the unloaded conditions.

METHODSSixty titanium mini-screws were used in this study. A total of 10 New Zealand white rabbits were randomly divided into 5 groups according to different healing periods. The stability was evaluated biomechanically at different time points. One-way ANOVA and correlation analyses were used.

RESULTS(1) After 4 weeks and 8 weeks of healing, maximal pull-out loads were (179.68 +/- 24.65) N and (212.06 +/- 42.51) N, respectively. The maximal torques were (0.47 +/- 0.13) N.m and (0.61 +/- 0.16) N.m, respectively. (2) Significant difference in maximal torque was found between 4 week and 8 week healing groups. (3) Both reverse torque and pull-out load significantly correlated with healing time.

CONCLUSIONSFourth-week is a critical time point in the progress of osseointegration. Within 8 weeks of healing process, the stability of implant was significantly correlated with healing time.

Animals ; Bone Screws ; Dental Implantation, Endosseous ; Dental Implants ; Dental Stress Analysis ; Male ; Orthodontic Anchorage Procedures ; Osseointegration ; physiology ; Rabbits ; Stress, Mechanical ; Time Factors ; Titanium ; Torque ; Wound Healing ; physiology

OBJECTIVETo analyze the relationships between MRI image changes of lateral pterygoid muscle (LPM), disc position and condylar mobility.

METHODSTwenty Class II patients were chosen and MRI images of LPM were taken. The relationships between MRI image changes of LPM, disc position and condylar mobility were analyzed.

RESULTSThe rate of MRI image changes of LPM in Class II patients was about 45%. No significant correlations were found between MRI image changes of LPM, condylar mobility and disc position.

CONCLUSIONSMRI image changes of LPM in Class II patients was common but no significant correlations were found between MRI image changes of LPM, condylar mobility and disc position.

Child ; Female ; Humans ; Magnetic Resonance Imaging ; Male ; Malocclusion, Angle Class II ; pathology ; physiopathology ; Pterygoid Muscles ; pathology ; Range of Motion, Articular ; Temporomandibular Joint ; physiopathology

OBJECTIVETo record and analyze the characteristics of condyle movement before and after functional treatment in Angle class II division 1 malocclusion (II(1)) patients.

METHODSTwenty Angle II(1) patients were included in the study and 20 Angle I patients without temporomandibular disorders symptoms served as controls. Computer aided diagnosis axiograph (CADIAX) was used to record the condyle movement in Angle II(1) patients and that caused by functional appliance treatment during mouth opening and closing.

RESULTSThe tracing were vertically displayed. Value Z [L: 2.21 (1.01) mm, R: 1.12 (1.02) mm] and sagittal condylar inclination [L: 12.89 (9.12) degrees, R: 12.12 (8.89) degrees] were increased significantly in Angle II(1) patients compared with those in control group (P < 0.05). After functional treatment, the condyle movement in Angle II(1) patients was close to normal (P > 0.05).

CONCLUSIONSTypical characteristics of condyle movement were found in Angle II(1) patients and it was stable and repeatable. Functional therapy had a positive effect on temporomandibular joint function in Angle II(1) patients.

Female ; Humans ; Male ; Malocclusion, Angle Class II ; physiopathology ; therapy ; Mandibular Condyle ; physiopathology ; Temporomandibular Joint ; physiopathology

OBJECTIVETo analyze the distribution of single nucleotide polymorphisms (SNP) of growth hormone receptor (GHR) gene in Chinese Han ethnic population.

METHODSThe sample of 106 unrelated healthy Chinese Hans was studied by sequencing exons of the GHR gene to detect SNP.

RESULTSThere were 6 SNP spots identified in exon 6 and exon 10. Five of them were found in exon 10, and one in exon 6. There were differences between the allele frequencies of the SNP we found and those in the NCBI database. The highest heterozygosity of the SNP was found at 1630 A > C (I526L), which was 47.6%. The SNP 1483 A > C (P477T), 1735 A > C (P561T) and 1319 G > T (C422F) had polarity change. The SNP 536 A > G in exon 6 from the NCBI database was not detected in this population. The allele distribution of SNP was in good unity with the Hardey-Weinberg equilibrium.

CONCLUSIONIt is suggested that the SNP of GHR are unevenly distributed and different in different ethnic populations.

Asian Continental Ancestry Group ; ethnology ; Female ; Gene Frequency ; Humans ; Male ; Polymorphism, Single Nucleotide ; Receptors, Somatotropin ; genetics