ABSTRACT
Objective: To investigate the effects of two-step retraction and en-masse retraction on tooth movement pattern of anterior teeth and posterior anchorage with clear aligners using three-dimensional finite element analysis. Methods: A finite element model of maxillary first premolar extraction case undergoing clear aligner treatment was established based on maxillofacial cone-beam CT data of a 24-year-old adult male with individual normal occlusion, who visited Department of Oral Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine for impacted mandibular third molar in June, 2022. The initial tooth displacement of five anterior retraction protocols (two-step with canine retraction, two-step with incisor bodily retraction, two-step with incisor retraction-overtreatment, en-masse bodily retraction, and en-masse retraction-overtreatment) were evaluated. Results: Two step with canine retraction caused distal tipping of the canine and labial tipping of the incisors (0.18° for central incisor and 0.13° for lateral incisor). Two step with incisor retraction caused mesial tipping of the canine. In two step with bodily retraction protocol, uncontrolled lingual tipping was found in central incisor (0.29°) and lateral incisor (0.32°). In two-step with incisor retraction-overtreatment protocol, the movement pattern of the incisors didn't change, but the inclinations reduced to 0.21° and 0.18°. En-masse retraction caused distal tipping of the canine. In en-masse bodily retraction protocol, uncontrolled lingual tipping was also found in central incisor (0.19°) and lateral incisor (0.27°). In en-masse retraction-overtreatment protocol, the central incisor showed controlled lingual tipping (0.02°) and the lateral incisor showed palatal root movement (0.03° labial inclination). Posterior teeth exhibited mesial tipping in all five protocols. Conclusion: En-masse retraction with incisor overtreatment was beneficial to incisor torque control in clear aligner treatment.
ABSTRACT
Objective To investigate the mutation of galactose-1-phosphate uridyltransferase gene (GALT gene) of galactosemia children by molecular methods.Methods Two children with galactosemia were investigated.The peripheral blood mononuclear cells were separated and total RNA was extracted.Then,whole cDNAs of GALT were amplified by reverse-transcription polymerase chain reaction;The PCR products were subcloned into T-easy vector and the positive clones were selected and sequenced;meanwhile,the PCR products were also digested by restricted enzymes and identified by restriction fragment length polymorphism.Results Two novel mutations were found in 2 children.In one child,A was changed into G in nucleotide 1006 of GALT gene,which led to amino acid residue M336V mutation.In the other child,A in nucleotide 779 of GALT gene was changed into T and led to amino acid residue H260L mutation.The 2 mutations were both missense mutation and heterozygous mutation.Conclusions Gene diagnosis is an useful method to improve the accuracy of galactosemia diagnosis and will provide valuable references for prenatal diagnosis,hematopoietic stem cell transplantation and gene therapy.