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.

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.

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

Three-dimensional(3D) digital technology has been widely used in the field of orthodontics in clinical examination,diagnosis,treatment and curative effect evaluation.3D digital technology greatly improves the accuracy of diagnosis and treatment,and provides effective means for personalized orthodontic treatment.This review focuses on the application of 3D digital technology in the field of orthodontics.

Health and support of periodontal tissue is the basis for achieving excellent, safe and efficient orthodontic treatment outcome, which also guarantees the esthetics, stability and function of treatment objectives. The support of healthy periodontal tissue contributes to the stability of teeth. Orthodontic treatment also requires adaptive periodontal reconstruction during tooth movement. Well-aligned teeth and balanced occlusion play an important role in maintaining and improving periodontal homeostasis. Healthy orthodontic treatment can improve the health of periodontal structure and functions, which has to rely on the existence and reconstruction of healthy periodontal tissue. Therefore, orthodontics and periodontal health have dialectically close association and mutual maintenance. Favorable "periodontal support and escort" is indispensable for healthy orthodontic treatment.

"Guidelines for clear aligner orthodontic treatment (2021)" proposes clinical treatment recommendations in terms of practitioner requirements, clinical risks, diagnosis, treatment plan, and common clinical strategies for the orthodontic clear aligners technology. This article interprets the 2021 version of the guidelines to facilitate readers′ better understanding and application in clinical practice.