BACKGROUND:Age and dental age are shown to have some limitations in predicting skeletal maturity.
OBJECTIVE:To compare the mandibular length in boys and girls with Class I and Class II skeletal patterns by using the cervical vertebrae maturation, and to provide valid reference index for orthodontical treatment.
METHODS:The lateral cephalograms of the 160 cases of Class I (40 males and 40 females) and Class II (40 males and 40 females) skeletal patterns, aged 8-15 years, were taken before orthodontic treatment. The sample was grouped according to stages of the cervical vertebrae maturation (Hasse and Farman method), and the mandibular length was measured separately. The results were statistical y analyzed by the independent-sample t test.
RESULTS AND CONCLUSION:No matter you are a male or female, the mandibular length of Class I was greater than that of Class II at the early stages of growth and development. In the Class I pattern, the mandibular lengths of boys were greater than those of girls at accelerated, transition, and deceleration stages (P<0.05), whereas in the Class II pattern, the mandibular lengths of boys were greater than those of girls at accelerated, transition, and deceleration stages (P<0.05). The present results indicate a sexual dimorphism in the mandibular length at almost al stages of bone maturation, but the possibility of a later“catch up”growth period occurs on Class II girls. And this information has important orthodontic clinical implications.

Objective To investigate the effect of human pulp stem cells(hDPSC)-derived exosomes(Exo)modified by circRNA(circRNA)signal-induced proliferation-associated protein-like 1(SIPA1L1)on the angiogenesis of human umbilical vein endothelial cells(HUVEC).Methods hDPSC was isolated and cultured from pulp tissue,the circSIPA1L1 overexpression plasmid was transfected into hDPSC,and Exo was isolated and identified.HUVEC was divided into control group,hDPSC Exo group and circSIPA1L1-hDPSC Exo group.After culture for 48 h,the vasculoformation ability was detected by Matrigel matrix gel vasculoformation test,the expres-sion levels of vascular endothelial growth factor(VEGF),vascular endothelial growth factor receptor 2(VEGFR2)and placental growth factor(PGF)were determined by qRT-PCR and Western blot.Results The Exo was success-fully isolated from the untransfected hDPSC and the hDPSC transfected with circSIPA1L1,and compared with the HDPSC-derived Exo,the relative expression of circSIPA1L1 in the hDPSC Exo transfected with circSIPA1L1 was significantly up-regulated(P＜0.05).Compared with hDPSC Exo group,the number of HUVEC tubular structures in circSIPA1L1-hDPSC Exo group was significantly increased(P＜0.05),and the mRNA and protein relative expressions of VEGF,VEGFR2 and PGF were also significantly up-regulated(P＜0.05).Conclusions Modification of hDPSC-derived Exo by circRNA SIPA1L1 can promote angiogenesis,and the mechanism may be related to up-regulation of VEGF,VEGFR2 and PGF expression levels.