Maxillary protraction using customized mini-plates for anchorage in an adolescent girl with skeletal Class III malocclusion / 대한치과교정학회지

The treatment of skeletal Class III malocclusion in adolescents is challenging.Maxillary protraction, particularly that using bone anchorage, has been proven to be an effective method for the stimulation of maxillary growth. However, the conventional procedure, which involves the surgical implantation of mini-plates, is traumatic and associated with a high risk. Three-dimensional (3D) digital technology offers the possibility of individualized treatment. Customized miniplates can be designed according to the shape of the maxillary surface and the positions of the roots on cone-beam computed tomography scans; this reduces both the surgical risk and patient trauma. Here we report a case involving a 12-year-old adolescent girl with skeletal Class III malocclusion and midface deficiency that was treated in two phases. In phase 1, rapid maxillary expansion and protraction were performed using 3D-printed mini-plates for anchorage.The mini-plates exhibited better adaptation to the bone contour, and titanium screw implantation was safer because of the customized design. The orthopedic force applied to each mini-plate was approximately 400–500 g, and the plates remained stable during the maxillary protraction process, which exhibited efficacious orthopedic effects and significantly improved the facial profile and esthetics. In phase 2, fixed appliances were used for alignment and leveling of the maxillary and mandibular dentitions. The complete two-phase treatment lasted for 24 months. After 48 months of retention, the treatment outcomes remained stable.

Risk perception and management in orthodontic treatment / 中华口腔医学杂志

With the improvement of people′s living standards and oral health education, the demand for orthodontic treatment is increasing. The comprehensive goal of orthodontic treatment is not only to obtain esthetic dentition and appearance, but also to obtain oral health, general health and mental and psychological health. Therefore, how to effectively prevent the risks in orthodontic treatment is particularly important, and it is also an important content that orthodontists must master. In this paper, the prevention of related risks in orthodontic treatment was discussed.

Effects of water-aging for 6 months on the durability of a novel antimicrobial and protein-repellent dental bonding agent / 国际口腔科学杂志·英文版

Biofilms at the tooth-restoration bonded interface can produce acids and cause recurrent caries. Recurrent caries is a primary reason for restoration failures. The objectives of this study were to synthesize a novel bioactive dental bonding agent containing dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC) to inhibit biofilm formation at the tooth-restoration margin and to investigate the effects of water-aging for 6 months on the dentin bond strength and protein-repellent and antibacterial durability. A protein-repellent agent (MPC) and antibacterial agent (DMAHDM) were added to a Scotchbond multi-purpose (SBMP) primer and adhesive. Specimens were stored in water at 37 °C for 1, 30, 90, or 180 days (d). At the end of each time period, the dentin bond strength and protein-repellent and antibacterial properties were evaluated. Protein attachment onto resin specimens was measured by the micro-bicinchoninic acid approach. A dental plaque microcosm biofilm model was used to test the biofilm response. The SBMP + MPC + DMAHDM group showed no decline in dentin bond strength after water-aging for 6 months, which was significantly higher than that of the control (P  0.1). In conclusion, a bonding agent with MPC and DMAHDM achieved a durable dentin bond strength and long-term resistance to proteins and oral bacteria. The novel dental bonding agent is promising for applications in preventive and restorative dentistry to reduce biofilm formation at the tooth-restoration margin.

Effectiveness and long-term stability of maxillary protraction / 中华口腔医学杂志

Maxillary protaction is most commonly used for the treatment of growing skeletal class Ⅲ patients with a maxillary deficiency. The present article reviewed the advances in the use of maxillary protraction, including the case selection, the timing of the treatment, the effectiveness of rapid maxillary expansion, the pattern of the maxillary protraction and the long-term stability.

Three-dimensional printed miniplate used for maxillary protraction / 中华口腔医学杂志

The miniplate was designed and three-dimensional (3D) printed according to the positions of roots and tooth germs and then it was used as skeletal anchorage to protract the maxilla. The maxilla moved forward obviously after treatment. Custom designed and 3D printed miniplate could be used for maxillary protraction.

Progress of research on parathyroid hormone-related protein and bone metabolism / 基础医学与临床

PTH-related protein (PTHrP) is an abundant factor in bone which shows paracrine,endocrine,autocrine functions combined with PTHrP receptor and plays an important role in bone metabolism.Rencent years have witnessed that PTHrP plays a significant therapeutic effect on osteoporosis and exhibits some new functions.

Changes in force associated with the amount of aligner activation and lingual bodily movement of the maxillary central incisor / 대한치과교정학회지

OBJECTIVE: The purposes of this study were to measure the orthodontic forces generated by thermoplastic aligners and investigate the possible influences of different activations for lingual bodily movements on orthodontic forces, and their attenuation. METHODS: Thermoplastic material of 1.0-mm in thickness was used to manufacture aligners for 0.2, 0.3, 0.4, 0.5, and 0.6 mm activations for lingual bodily movements of the maxillary central incisor. The orthodontic force in the lingual direction delivered by the thermoplastic aligners was measured using a micro-stress sensor system for the invisible orthodontic technique, and was monitored for 2 weeks. RESULTS: Orthodontic force increased with the amount of activation of the aligner in the initial measurements. The attenuation speed in the 0.6 mm group was faster than that of the other groups (p < 0.05). All aligners demonstrated rapid relaxation in the first 8 hours, which then decreased slowly and plateaued on day 4 or 5. CONCLUSIONS: The amount of activation had a substantial influence on the orthodontic force imparted by the aligners. The results suggest that the activation of lingual bodily movement of the maxillary central incisor should not exceed 0.5 mm. The initial 4 or 5 days is important with respect to orthodontic treatment incorporating an aligner.

Effect of 2-methacryloyloxyethyl phosphorylcholine on the protein-repellent property of dental adhesive / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the effect of 2-methacryloyloxyethyl phosphorylcholine (MPC) and nanoparticles of amorphous calcium phosphate (NACP) on the protein-repellent property of dental adhesive.</p><p><b>METHODS</b>MPC and NACP were incorporated into SBMP as the test group. Scotchbond Multi-Purpose (SBMP) was used as control group. Human dentin shear bond strengths were measured. Protein adsorption onto samples was determined by micro bicinchoninic acid (BCA) method. A dental plaque microcosm biofilm model with human saliva as inoculum was used to investigate biofilm viability.</p><p><b>RESULTS</b>The dentin bond strength of modified group was (28.7±2.2) MPa, which was not significantly different from that of the SBMP control group. The amount of protein adsorption in the modified group and the SBMP control group were (0.21±0.02) µg/cm(2) and (4.17±0.45) µg/cm(2) respectively. Lactic acid production of biofilms in modified group and SBMP control were (7.71 ± 1.01) mmol/L and (19.18 ± 2.34) mmol/L repectively.</p><p><b>CONCLUSIONS</b>MPC-NACP based dental adhesive greatly reduce the protein adsorption and bacterial adhesion, without compromising dentin shear bond strength. This novel bonding agent may have wide application.</p>

Measurement of orthodontic forces exerted on the upper right central incisor with the increase of the distance of tooth movement and thickness of the aligner / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To measure the orthodontic forces exerted on the upper right central incisor with the increase of the distance of tooth movement and the thickness of the aligner.</p><p><b>METHODS</b>The labial movement of upper right central incisor at various distances (0.3, 0.6, 0.9, 1.2, 1.5, 1.8 mm) was designed and the stereolithography model (2 times bigger than the original model) was created with 3-D scanning and tomography output. These models were used to fabricate the aligners with different thicknesses (0.8, 1.0, 1.5 and 2.0 mm) of the thermoplastic materials (6 samples for various distances of tooth movement and thicknesses). Orthodontic forces exerted on the upper right central incisor were measured with the micro-stress sensor measurement system.</p><p><b>RESULTS</b>The orthodontic forces increased with the increase of the thickness of the aligner at the same distance of tooth movement (P < 0.05). The orthodontic force was (1.237 ± 0.082), (1.543 ± 0.059), (3.602 ± 0.102), (6.734 ± 0.063) N when the labial movement of upper right central incisor was 0.3 mm with the aligner of 0.8, 1.0, 1.5, 2.0 mm. The orthodontic forces also increased with the increase of the distance of the tooth movement at the same thickness of the aligner(P < 0.05). The orthodontic force of the aligner of 0.8 mm were (1.354 ± 0.039), (1.288 ± 0.037), (1.479 ± 0.031), (1.799 ± 0.039) N when the upper right central tooth labial movement at 0.6, 0.9, 1.2, 1.5 mm.</p><p><b>CONCLUSIONS</b>The orthodontic forces increased with the increase of the distance of tooth movement and the thickness of the aligner.</p>

Effect of light centrifugal force on the asporin gene expression in human periodontal ligament cells / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To observe the expression of asporin, bone morphogenetic protein-2 (BMP-2) and alkaline phosphatase (ALP) in cultured human periodontal ligament cells in vitro under relative centrifugal force.</p><p><b>METHODS</b>Human periodontal ligament cell was cultured in vitro and applied 30 ×g centrifugal force for 0, 1, 2, 6, 10 hours. The expression of asporin, BMP-2 and ALP was observed with real time-PCR.</p><p><b>RESULTS</b>All the cells showed normal figuration. The expression of asporin, BMP-2, ALP in no force loading group did not have any statistical significance change (P > 0.05). In 1 hour force loading group, the expressions of asporin and BMP-2 were 0.50 ± 0.05 and 0.40 ± 0.13. In 2 hour force loading group, the expressions of asporin and BMP-2 were 0.42 ± 0.09 and 0.58 ± 0.19, which decreased significantly from no force loading group (P < 0.05). The expression of asporin and BMP-2 increased significantly in 6 hour force loading group than in 1 and 2 hour force loading groups (P < 0.05). Then the expression of asporin decreased to no force loading group level (P > 0.05) and the expression of BMP-2 decreased rapidly lower than no force loading group level (P < 0.05). During the 10 hour interval of stress loading, the expression of asporin and BMP-2 showed a positive correlation (r = 0.995, P < 0.05).</p><p><b>CONCLUSIONS</b>The expression of asporin in human periodontal ligament cell was stable. Short and light centrifugal force could up-regulate the expression of asporin rapidly, and suppress the abnormal BMP-2 expression back to baseline level.</p>

Occlusal contacts during protrusion and lateral movements after orthodontic treatment / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To observe the occlusal contacts during protrusion and lateral movements in adolescent patients after orthodontic treatment.</p><p><b>METHODS</b>Sixteen adolescent patients who achieved normal dentition 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 contacts during protrusion and lateral movements in the two groups were recorded with T-Scan II system and compared.</p><p><b>RESULTS</b>The prevalence of occlusal interferences in the posterior segment in the experimental group was high and most of them were on the second molars. The value of disclusion time during left lateral movements, right lateral movements and protrusion in the experimental group were (1.504 +/- 0.681), (1.532 +/- 0.913), (1.358 +/- 0.791) s. The value of disclusion time during left lateral movements, right lateral movements and protrusion in the control group were (0.470 +/- 0.059), (0.483 +/- 0.045), (0.482 +/- 0.047) s. The results in the experimental group were significantly longer than those of control group (P < 0.01).</p><p><b>CONCLUSION</b>Although the patients achieved normal dentition after orthodontic treatment, their disclusion time were longer than those in healthy adolescents and young adults with normal occlusion.</p>

Utility of three-dimensional soft tissue facial morphometry and conventional cephalometrics in people with normal occlusion / 华西口腔医学杂志

<p><b>OBJECTIVE</b>The purpose of this study was to compare the data of three-dimensional soft tissue obtained by using a three-dimensional digital photogrammetry and the two-dimensional data obtained by using a conventional cephalometry.</p><p><b>METHODS</b>Three-dimensional characters of facial soft tissue were obtained by using four digital cameras. The authors developed necessary hardware and software systems and applied in stereophotogrammetry to obtain the data of three-dimensional facial soft tissues. A total of 40 people with normal occlusion, including 20 males and 20 females, were examined with both three-dimensional soft tissue facial morphometry and cephalometry. Three-dimensional soft tissue facial morphometry was performed, and their relations with facial cephalometry were analyzed.</p><p><b>RESULTS</b>Significant correlations were found between 6 pairs of linear measurements, 4 pairs of angular measurements and 3 pairs of linear distant ratio measurements. The data obtained by three-dimensional facial soft tissue morphometry and two-dimensional cephalometry was identical.</p><p><b>CONCLUSION</b>There was a correlation between the three-dimensional soft tissue facial morphometry and facial cephalometry. The data obtained by the three-dimensional soft tissue facial morphometry can partially represent facial hard tissue.</p>

Histomorphometric characterization of osseointegration after implantation of dental mini-screw / 实用口腔医学杂志

Objective:To study the osseointegration after implantation of dental mini-screw under unloaded condition by histomorphometric observations.Methods:30 titanium mini-screws were used. 3 titanium implant miniscrews were implanted into each tibia of 10 New Zeland White rabbits at a distance of 10 mm between 2 mini-screws. 2 animals were sacrificed immediately,1,2,4 and 8 weeks after operation respectively.Samples of the screws with surrounding bone tissue were examined by HE staining.Results:Progressive changes were observed in the implant-bone interface.1 and 2 weeks after operation collagen fibers, locally absorbed areas and cancellous bones with loose connective tissues were found.4 weeks after operation compact cortical bone was observed.8 weeks after operatoin lamellar bone and second remodeling were found.Conclusion:Osseointegration between implanted mini-screw and bone tissue may complete in 8 weeks in rabbit tibia.