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Influence of long and short arms of X chromosome on maxillary molar crown morphology.

ABSTRACT: Although genes on the human X chromosome reportedly influence tooth crown morphology, little is known about X chromosome activation or inactivation systems relevant to morphological variations. We assessed the relationships between tooth crown size and crown morphological traits in females with Turner syndrome, the variants of which include complete absence of one X chromosome, lack of the short arm (Xp), or duplication of the long arms (Xq), and then estimated the functions of Xp and Xq in the process of unilateral X chromosome inactivation during tooth crown development. The mesiodistal and buccolingual diameters in the maxillary first (M1) and second (M2) permanent molars were compared among X chromosome karyotypes by multiple regression analyses, and their relationships with the development of Carabelli's cusp and the distolingual cusp were analyzed using logistic regression analysis. The crown sizes increased in the order of the 46,X,i(Xq) karyotype, 45,X and 45,X/46,XX karyotypes, and control group. A lower frequency of Carabelli's cusp and higher frequency of a reduced distolingual cusp in M1 were characteristics of Turner syndrome. The overall M1 and M2 crown sizes differed among the X chromosome karyotypes, whereas a smaller crown size was associated with a reduced distolingual cusp but not with Carabelli's cusp. Considering the differences in chromosome arrangement among females with Turner syndrome and the process of unilateral X chromosome inactivation, the observed results can be considered in terms of quantity or number of promoters/inhibitors during tooth crown development. The X chromosome karyotypes have a strong influence on the overall crown sizes of the M1 and M2 molars because those karyotypes with variable numbers of active gene regions directly influence tooth germ development in an early stage of human odontogenesis. The later forming cusps, such as the distolingual cusp and Carabelli's cusp, may be affected by this developmental prerequisite.

SUBMITTER: Nakayama M

PROVIDER: S-EPMC6237344 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Influence of long and short arms of X chromosome on maxillary molar crown morphology.

Nakayama Mitsuko M Kondo Osamu O Pesonen Paula P Alvesalo Lassi L Lähdesmäki Raija R

PloS one 20181115 11

Although genes on the human X chromosome reportedly influence tooth crown morphology, little is known about X chromosome activation or inactivation systems relevant to morphological variations. We assessed the relationships between tooth crown size and crown morphological traits in females with Turner syndrome, the variants of which include complete absence of one X chromosome, lack of the short arm (Xp), or duplication of the long arms (Xq), and then estimated the functions of Xp and Xq in the ...[more]

PMID: 30439977

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Project description:Dentinogenesis, a formation of dentin by odontoblasts, is an essential process during tooth development. Bone morphogenetic proteins (BMPs) are one of the most crucial growth factors that contribute to dentin formation. However, it is still unclear how BMP signaling pathways regulate postnatal crown and root dentinogenesis. BMPs transduce signals through canonical Smad and non-Smad signaling pathways including p38 and ERK signaling pathways. To investigate the roles of Smad and non-Smad signaling pathways in dentinogenesis, we conditionally deleted Bmpr1a, which encodes the type 1A receptor for BMPs, to remove both Smad and non-Smad pathways in Osterix-expressing cells. We also expressed a constitutively activated form of Bmpr1a (caBmpr1a) to increase Smad1/5/9 signaling activity without altered non-Smad activity in odontoblasts. To understand the function of BMP signaling during postnatal dentin formation, Cre activity was induced at the day of birth. Our results showed that loss of BmpR1A in odontoblasts resulted in impaired dentin formation and short molar roots at postnatal day 21. Bmpr1a cKO mice displayed a reduction of dentin matrix production compared to controls associated with increased cell proliferation and reduced Osx and Dspp expression. In contrast, caBmpr1a mutant mice that show increased Smad1/5/9 signaling activity resulted in no overt tooth phenotype. To further dissect the functions of each signaling activity, we generated Bmpr1a cKO mice also expressing caBmpr1a to restore only Smad1/5/9 signaling activity. Restoring Smad activity in the compound mutant mice rescued impaired crown dentin formation in the Bmpr1a cKO mice; however, impaired root dentin formation and short roots were not changed. These results suggest that BMP-Smad signaling in odontoblasts is responsible for crown dentin formation, while non-Smad signaling may play a major role in root dentin formation and elongation. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Project description:OBJECTIVE:To explore the feasibility of immediate implantation after tooth extraction in the maxillary molar socket with poor bone quality beneath the sinus. METHODS:We collected the data from the patients undergoing extraction of maxillary molars with poor bone quality between the sockets and sinuses. Sinus lifting and immediate implant following the extraction were performed simultaneously in these cases, and the primary stability of the implants, wound healing, and changes of the sinus were observed. At 6 months after the operations, the crowns were installed on the implants. The masticatory function was observed, and the growth of the alveolar bones and their changes after the operations were examined using microcomputed tomography (MCT). RESULTS:We analyzed 32 extraction cases with immediate implantation in the maxillary molar sockets with poor bone quality beneath the sinus. The average age of the patients was 59.8 years, and the length and diameter of the implant ranged from 8.5 to 10 mm and from 4.5 to 5.5 mm, respectively. The torque force of the implants varied from the minimum (in which cases the implants remained fixed after insertion with fingers) to the maximum of 30 N·cm. The postoperative recovery was uneventful in all the cases and no failed or movable implants were found. At 6 months after the operation, none of the patients showed abnormalities in the sinus, and in all the cases the crowns were successfully installed on the implants with good recovery of the masticatory functions. Follow-up of the patients for 12 to 96 months after the operation showed successful immediate implantation in all the cases. After the operation, the changes of the mean alveolar ridge heights on the buccal, palatal, mesial, and distal sides of the patients were 0.8069±0.6253 mm (t=1.2904, P>0.1), 0.5272± 0.3331 mm (t=1.5836, P>0.05), 0.5416±0.4048 mm (t=1.3379, P>0.05), and 0.5172±0.3874 mm (t=1.3351, P>0.05), respectively; the change of the alveolar ridge width was 0.5522±0.4381 mm (t=1.2604, P>0.1) mm. The dimension of the alveolar bone underwent no significant changes after the operation in these patients. CONCLUSIONS:Immediate implantation in the maxillary extraction socket with a poor bone quality can avoid damages to the sinus and achieve good outcomes with such advantages of less trauma, full use of the innate gingiva and alveolar ridge, and well preserved morphology of the alveolar ridge as compared with delayed implantation.

Dataset Information

Influence of long and short arms of X chromosome on maxillary molar crown morphology.

Publications

Influence of long and short arms of X chromosome on maxillary molar crown morphology.

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