Clinical features and FGFR3 mutations of children with achondroplasia / 中国当代儿科杂志

OBJECTIVES@#To study the clinical features and fibroblast growth factor receptor 3 (FGFR3) gene mutations of children with achondroplasia (ACH) through an analysis of 17 cases.@*METHODS@#A retrospective analysis was performed on the clinical data and FGFR3 gene detection results of 17 children with ACH who were diagnosed from January 2009 to October 2021.@*RESULTS@#Of the 17 children with ACH, common clinical manifestations included disproportionate short stature (100%, 17/17), macrocephaly (100%, 17/17), trident hand (82%, 14/17), and genu varum (88%, 15/17). The common imaging findings were rhizomelic shortening of the long bones (100%, 17/17) and narrowing of the lumbar intervertebral space (88%, 15/17). Major complications included skeletal dysplasia (100%, 17/17), middle ear dysfunction (82%, 14/17), motor/language developmental delay (88%, 15/17), chronic pain (59%, 10/17), sleep apnea (53%, 9/17), obesity (41%, 7/17), foramen magnum stenosis (35%, 6/17), and hydrocephalus (24%, 4/17). All 17 children (100%) had FGFR3 mutations, among whom 13 had c.1138G>A hotspot mutations of the FGFR3 gene, 2 had c.1138G>C mutations of the FGFR3 gene, and 2 had unreported mutations, with c.1252C>T mutations of the FGFR3 gene in one child and c.445+2_445+5delTAGG mutations of the FGFR3 gene in the other child.@*CONCLUSIONS@#This study identifies the unreported mutation sites of the FGFR3 gene, which extends the gene mutation spectrum of ACH. ACH is a progressive disease requiring lifelong management through multidisciplinary collaboration.

Root Canal Morphology of Mandibular Incisors with Double Root Canals in a Chinese Population.

OBJECTIVE: To investigate the bilateral symmetry of double root canals, variation in root canal bifurcation and position of canal orifices in mandibular incisors in a Chinese population. METHODS: A total of 149 subjects with mandibular incisors with two canals were selected from 866 patients based on CBCT images and divided into three groups: group 1 (< 21 years), group 2 (21-40 years) and group 3 (> 40 years). The prevalence of bilateral symmetry of double root canals (type III and type V), the distance between the cementoenamel junction (CEJ) and the bifurcation (D1) and the distance between the two canal orifices (D2) were calculated and analysed. RESULTS: The bilateral symmetry of type III for mandibular central incisors (MCIs) (44.4%) was significantly lower than that for mandibular lateral incisors (MLIs) (63.4%). D1 was greater in group 1 (4.63 ± 1.35mm) than in group 2 (3.99 ± 1.02 mm) and group 3 (3.90 ± 1.95 mm). D2 was shorter in in MCIs (0.65 ± 0.20 mm) than in MLIs (0.74 ± 0.22 mm). CONCLUSION: Special attention is required in the root canal treatment of mandibular incisors, especially in patients aged above 21 years.

A predictive analysis of the association between clinical phenotypes and genotypes in children with Becker muscular dystrophy/Duchenne muscular dystrophy / 中国当代儿科杂志

OBJECTIVE@#To study the association between clinical phenotypes and genotypes in children with Becker muscular dystrophy (BMD)/Duchenne muscular dystrophy (DMD) so as to provide a theoretical basis for disease management, gene therapy, and prenatal diagnosis.@*METHODS@#A retrospective analysis was performed for the clinical data and gene detection results of 52 children with BMD/DMD. Multiplex ligation-dependent probe amplification (MLPA) was used to detect the DMD gene. The children with negative results of MLPA were further screened by exon chip capture combined with next-generation sequencing (NGS). The mothers of 20 probands were validated by sequencing.@*RESULTS@#The pathogenic genes for BMD/DMD were detected in 50 children by MLPA and NGS, with a detection rate of 96%. Among the 52 children, 36 (69%) had gene deletion, 7 (13%) had duplication, and 7 (13%) had micromutation. Among the 43 children with deletion/duplication, 32 had DMD and 11 had BMD; 37 children (86%) met the reading frame rule, among whom 27 (96%) had DMD and 10 (67%) had BMD. All 7 children with micromutation had DMD.@*CONCLUSIONS@#The reading frame rule has an extremely high predictive value for DMD but a limited predictive value for BMD.

[Cone-beam computed tomography analysis of root canal configuration of 4 674 mandibular anterior teeth].

OBJECTIVE: To investigate the root canal configuration of mandibular anterior teeth with cone-beam computed tomography (CBCT). METHODS: The CBCT imaging data of 866 patients who visited Peking University School of Stomatology from October 2012 to July 2013 were inspected by an endodontist anda radiologists together. A total of 4 674 mandibular anterior teeth were involved. The number of root, root canals and root canal configuration were observed and analyzed statistically (Chi-squared test). RESULTS: All the mandibular central incisors and lateral incisors were single root, and 0.7% (11/1 542) of canines were double roots. 6.7% (105/1 566) of central incisors, 17.4% (273/1 566) of lateral incisors and 3.0% (46/1 542) of canines had double root canals. The frequency of symmetry of double root canal was 58.7% (37/63) in central incisors, 76.1% (108/142) in lateral incisors and 29.6% (8/27) in canines. The highest frequency of double root canals in different ages was 9.8% (28/287, 31-40 years) in central incisors, 21.5% (61/284, 31-40 years) in lateral incisors and 9.2% (19/207, ≥51 years) in canines. Vertucci type III canal configurations were the most prevalent in mandibular anterior teeth. CONCLUSION: The double root canals are most common in mandibular lateral incisors. The highest incidence of symmetry of double root canal is also observed in mandibular lateral incisors. Vertucci type III canal configurations are the most frequent type in mandibular anterior teeth.

[Effect of cementation on fracture toughness of chair-side CAD/CAM ceramic].

OBJECTIVE: Chair-side CAD/CAM ceramic restorations are esthetic with a time-saving procedure. However, ceramic restorations often failed due to fracture. This study was to investigate the effect of cement thickness on fracture toughness and hardness of CAD/CAM ceramic. METHODS: Machinable ceramic blocks for CAD/CAM (Sirona CEREC Blocs) were cut into 9 slices (12 mm×14 mm×2 mm) using a diamond saw (Leica SP 1600) and polished carefully with sandpaper / diamond pastes to yield a mirror-like surface. LIGHT-CORE(TM) was used to prepare resin slices with dimension of 12 mm×14 mm×2 mm. The polished ceramic slices were then randomly divided into 3 groups and cemented to resin slices using Multilink Automix: Group 1, no cement; Group 2, the thickness of cement was 50 µm; Group 3, the thickness of cement was 100 µm. Hardness (H) was determined by Vickers indentation technique using micro-hardness tester (HMV-2T Shimadzu) with a load of 19.6 N for 15 s. The fracture toughness (K(IC)) was calculated by K(IC) = 0.016 (E/H)(0.5)(P/c(1.5)), where P=applied load, c=crack length, E=elastic modulus, H= (0.47 P/a(2)), a=half diagonal of the indentation. RESULTS: The fracture toughness for Group 1 (no cement) was (1.02±0.11) MN/m(3/2), for Group 2 and Group 3 was (0.99±0.10) MN/m(3/2) and (0.97±0.14) MN/m(3/2). Group 3 showed lower fracture toughness than group 1 (P<0.05). The Weibull parameter m of group 2 was the highest and K(0) of three groups were 1.08 MN/m(3/2), 1.04 MN/m(3/2) and 1.03 MN/m(3/2) respectively. The hardness for Group 1 was (6.68±0.73) GPa, group 2 [(6.85±0.64) GPa], group 3 [(6.81±0.98) GPa]. There was no significant deference in hardness among the 3 groups (P>0.05). CONCLUSION: Thickness of cementation may affect fracture toughness of machinable ceramic, therefore, a thinner film of cementation is recommended for Chair-side CAD/CAM ceramic restorations.