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.

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.

OBJECTIVETo observe the occlusal contacts during protrusion and lateral movements in adolescent patients after orthodontic treatment.

METHODSSixteen 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.

RESULTSThe 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).

CONCLUSIONAlthough the patients achieved normal dentition after orthodontic treatment, their disclusion time were longer than those in healthy adolescents and young adults with normal occlusion.

Adolescent ; Adult ; Dental Occlusion ; Humans ; Molar ; Tooth Movement Techniques ; Young Adult

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.

OBJECTIVEThe 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.

METHODSThree-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.

RESULTSSignificant 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.

CONCLUSIONThere 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.

Adult ; Cephalometry ; Face ; anatomy & histology ; Female ; Humans ; Image Processing, Computer-Assisted ; Imaging, Three-Dimensional ; Male ; Photogrammetry ; methods ; Radiography ; Reference Values ; Skull ; diagnostic imaging

Objective: A three-dimensional-printed individual titanium plate was applied for maxillary protraction to eliminate side effects and obtain the maximum skeletal effect. This study aimed to explore the stress distribution characteristics of sutures during maxillary protraction using individual titanium plates in various directions and locations. Methods: A protraction force of 500 g per side was applied at forward and downward angles between 0° and 60° with respect to the Frankfort horizontal plane, after which the titanium plate was moved 2 and 4 mm upward and downward, respectively. Changes in sutures with multiple protraction directions and various miniplate heights were quantified to analyze their impact on the maxillofacial bone. Results: Protraction angle of 0–30° with respect to the Frankfort horizontal plane exhibited a tendency for counterclockwise rotation in the maxilla. At a 40° protraction angle, translational motion was observed in the maxilla, whereas protraction angles of 50–60° tended to induce clockwise rotation in the maxilla. Enhanced protraction efficiency at the lower edge of the pyriform aperture was associated with increased height of individual titanium plates. Conclusions Various protraction directions are suitable for patients with different types of vertical bone surfaces. Furthermore, when the titanium plate was positioned lower, the protraction force exhibited an increase.

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.
Incisor* ; Relaxation

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.

Objectives : The purposes of this study were to evaluate the long-term mechanical property, bacteria-killing ability, protein resistance and cytotoxicity of a novel antibacterial methyl methacrylate (MMA) resin. Methods : The 2-methacryloyloxyethyl phosphorylcholine (MPC) has been added into the MMA used for making Hawley orthodontic retener according to the mass percentage 0% (control group), 1.5%, 2.25%, 3%, 4.5% and 6%. Specimens from the control group and MPC group were water-aged for 1 d, 90 d and 180 d, and then the universal material testing machine was used to investigate the long-term mechanical properties of the modified MMA specimens in the oral environment. The biofilm metabolic activity, colony-forming unit (CFU) and live/dead staining assay of the biofilms in the control group and MPC group in the oral environment were tested using the dental plaque biofilm model. The micro-bicinchoninic acid (BCA) method was used to determine the amount of protein adsorbed on the specimens. The MTT method was used to evaluate the cytotoxicity of the control group and MPC group. Results : In the simulated oral environment, the addition of 0% to 3% MPC had no significant effect on the mechanical properties of the MMA specimen (P > 0.05). The control group and the modified MMA specimens with 3%MPC were statistically significant in time and the interaction effects between the two groups (P < 0.05). With increasing intervention time, the mechanical strength of both groups decreased, and the effect of time varied with grouping. The protein adsorption on the surface of the modified MMA material after adding 3% MPC decreased by approximately 80%, the metabolic activity of the biofilm decreased by approximately 50%, and biofilm CFU counts decreased by approximately 70% (P < 0.05) compared with the control. There was no statistically significant difference in time or interaction effects between the two groups. The amount of live green bacteria in the 3% MPC group decreased significantly after 1, 90, and 180 d of water aging. There was no significant difference in cytotoxicity between the control group and the MPC group (P > 0.05). Conclusions The addition of MPC into the MMA resin did not compromise the mechanical properties of the resin and exhibited long-lasting antibacterial and protein-repellent effects.

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.