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Guignardat JF, Raoul G, Ferri J, Sciote JJ, Nicot R. Systematic review of the histological and functional effects of botulinum toxin A on masticatory muscles: Consideration in dentofacial orthopedics and orthognathic surgery. Ann Anat 2024; 256:152302. [PMID: 39038690 DOI: 10.1016/j.aanat.2024.152302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 05/31/2024] [Accepted: 07/03/2024] [Indexed: 07/24/2024]
Abstract
INTRODUCTION Botulinum toxin type A causes muscle paralysis and is widely used in the masticatory muscle for stomatognathic diseases, such as temporomandibular disorder, bruxism, or masseteric hypertrophy. Nonetheless, its muscular effect remains unclear. Better understanding could aid improved use and perhaps new indications, particularly in dentofacial orthopaedics and orthognathic surgery. METHODS This systematic review explored the histologic and functional effects of botulinum toxin in animal and human masticatory muscles and was conducted in accordance with the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The MEDLINE, Web of Science, and Cochrane Library electronic databases were searched for relevant articles. The inclusion criteria were human or animal masticatory muscle analysis after botulinum toxin injection(s) AND histological structural/ultrastructural analysis by optical or electronic microscopy OR functional effect analysis by bite force evaluation (occlusal force analyzer) and muscle activity (electromyography). RESULTS Of an initial 1578 articles, 44 studies were eventually included. Botulinum toxin injection in the masticatory muscle altered its histological structure and functional properties. The human and animal studies revealed ultrastructural change, atrophy, and fiber type modifications of the masticatory muscles after one injection. Botulinum toxin decreased bite force and muscle activity, but recovery was uncertain. CONCLUSIONS Muscle forces applied on the skeleton is a key feature of facial growth. Masticatory muscle paralysis changes mechanical stress on bones, which rebalances the force applied on facial bones. This new balance could benefit dental deformity or surgical relapse. Therefore, botulinum toxin could limit the orthognathic effect of the masticatory muscles in such patients. Given the uncertain recovery, multiple injections should be avoided, and usage should not deviate from established consensus.
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Affiliation(s)
| | - Gwénaël Raoul
- Univ. Lille, Inserm, CHU Lille, U1008 - Advanced Drug Delivery Systems, Department of Oral and Maxillofacial Surgery, F-59000 Lille, France
| | - Joël Ferri
- Univ. Lille, Inserm, CHU Lille, U1008 - Advanced Drug Delivery Systems, Department of Oral and Maxillofacial Surgery, F-59000 Lille, France
| | - James J Sciote
- Department of Orthodontics, Temple University, Philadelphia, Pennsylvania, USA
| | - Romain Nicot
- Univ. Lille, Inserm, CHU Lille, U1008 - Advanced Drug Delivery Systems, Department of Oral and Maxillofacial Surgery, F-59000 Lille, France.
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Zhang X, Wang F, Ou M, Liu H, Luo Q, Fei S, Zhao J, Chen K, Zhao Q, Li K. Effects of Myostatin b Knockout on Offspring Body Length and Skeleton in Yellow Catfish ( Pelteobagrus fulvidraco). BIOLOGY 2023; 12:1331. [PMID: 37887041 PMCID: PMC10604553 DOI: 10.3390/biology12101331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 10/01/2023] [Accepted: 10/09/2023] [Indexed: 10/28/2023]
Abstract
Based on obtaining mstnb gene knockout in Pelteobagrus fulvidraco, a study on the effect of the mstn gene on skeletal morphology and growth was performed by comparing the number and length of the vertebrae of mutant and wild-type fish in a sibling group of P. fulvidraco, combined with the differences in cells at the level of vertebral skeletal tissue. It was found that mstnb gene knockdown resulted in a reduction in the number of vertebrae, the length, and the intervertebral distance in P. fulvidraco, and these changes may be the underlying cause of the shorter body length in mutant P. fulvidraco. Further, histological comparison of the same sites in the mstn mutant and wild groups of P. fulvidraco also revealed that the number and density of osteocytes were greater in mstnb knockout P. fulvidraco than in wild-type P. fulvidraco. Our results demonstrated that when using genome editing technology to breed new lines, the effects of knockout need to be analyzed comprehensively and may have some unexpected effects due to insufficient study of the function of certain genes.
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Affiliation(s)
- Xincheng Zhang
- Key Laboratory of Tropical and Subtropical Fishery Resources Application and Cultivation, Ministry of Agriculture and Rural Affairs, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China; (X.Z.)
| | - Fang Wang
- Key Laboratory of Tropical and Subtropical Fishery Resources Application and Cultivation, Ministry of Agriculture and Rural Affairs, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China; (X.Z.)
| | - Mi Ou
- Key Laboratory of Tropical and Subtropical Fishery Resources Application and Cultivation, Ministry of Agriculture and Rural Affairs, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China; (X.Z.)
| | - Haiyang Liu
- Key Laboratory of Tropical and Subtropical Fishery Resources Application and Cultivation, Ministry of Agriculture and Rural Affairs, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China; (X.Z.)
| | - Qing Luo
- Key Laboratory of Tropical and Subtropical Fishery Resources Application and Cultivation, Ministry of Agriculture and Rural Affairs, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China; (X.Z.)
| | - Shuzhan Fei
- Key Laboratory of Tropical and Subtropical Fishery Resources Application and Cultivation, Ministry of Agriculture and Rural Affairs, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China; (X.Z.)
| | - Jian Zhao
- Key Laboratory of Tropical and Subtropical Fishery Resources Application and Cultivation, Ministry of Agriculture and Rural Affairs, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China; (X.Z.)
| | - Kunci Chen
- Key Laboratory of Tropical and Subtropical Fishery Resources Application and Cultivation, Ministry of Agriculture and Rural Affairs, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China; (X.Z.)
| | - Qingshun Zhao
- Model Animal Research Center, Nanjing University, 12 Xuefu Road, Pukou High-Tech Development Zone, Nanjing 210061, China
- Institute of Genome Editing, Nanjing YSY Biotech Company, No. 1 Amber Road, Nanjing 211812, China
| | - Kaibin Li
- Key Laboratory of Tropical and Subtropical Fishery Resources Application and Cultivation, Ministry of Agriculture and Rural Affairs, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510380, China; (X.Z.)
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Jeffery NS, Sarver DC, Mendias CL. Ontogenetic and in silico models of spatial-packing in the hypermuscular mouse skull. J Anat 2021; 238:1284-1295. [PMID: 33438210 PMCID: PMC8128773 DOI: 10.1111/joa.13393] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 12/18/2022] Open
Abstract
Networks linking single genes to multiple phenotypic outcomes can be founded on local anatomical interactions as well as on systemic factors like biochemical products. Here we explore the effects of such interactions by investigating the competing spatial demands of brain and masticatory muscle growth within the hypermuscular myostatin-deficient mouse model and in computational simulations. Mice that lacked both copies of the myostatin gene (-/-) and display gross hypermuscularity, and control mice that had both copies of the myostatin gene (+/+) were sampled at 1, 7, 14 and 28 postnatal days. A total of 48 mice were imaged with standard as well as contrast-enhanced microCT. Size metrics and landmark configurations were collected from the image data and were analysed alongside in silico models of tissue expansion. Findings revealed that: masseter muscle volume was smaller in -/- mice at day 1 but became, and remained thereafter, larger by 7 days; -/- endocranial volumes begin and remained smaller; -/- enlargement of the masticatory muscles was associated with caudolateral displacement of the calvarium, lateral displacement of the zygomatic arches, and slight dorsal deflection of the face and basicranium. Simulations revealed basicranial retroflexion (flattening) and dorsal deflection of the face associated with muscle expansion and abrogative covariations of basicranial flexion and ventral facial deflection associated with endocranial expansion. Our findings support the spatial-packing theory and highlight the importance of understanding the harmony of competing spatial demands that can shape and maintain mammalian skull architecture during ontogeny.
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Affiliation(s)
- Nathan S. Jeffery
- Institute of Life Course & Medical SciencesUniversity of LiverpoolLiverpoolUK
| | - Dylan C. Sarver
- Department of Orthopaedic SurgeryUniversity of MichiganAnn ArborMIUSA
- School of MedicineJohns Hopkins UniversityBaltimoreMDUSA
| | - Christopher L. Mendias
- Department of Orthopaedic SurgeryUniversity of MichiganAnn ArborMIUSA
- HSS Research InstituteHospital for Special SurgeryNew YorkNYUSA
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Du W, Bhojwani A, Hu JK. FACEts of mechanical regulation in the morphogenesis of craniofacial structures. Int J Oral Sci 2021; 13:4. [PMID: 33547271 PMCID: PMC7865003 DOI: 10.1038/s41368-020-00110-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 12/03/2020] [Accepted: 12/07/2020] [Indexed: 02/07/2023] Open
Abstract
During embryonic development, organs undergo distinct and programmed morphological changes as they develop into their functional forms. While genetics and biochemical signals are well recognized regulators of morphogenesis, mechanical forces and the physical properties of tissues are now emerging as integral parts of this process as well. These physical factors drive coordinated cell movements and reorganizations, shape and size changes, proliferation and differentiation, as well as gene expression changes, and ultimately sculpt any developing structure by guiding correct cellular architectures and compositions. In this review we focus on several craniofacial structures, including the tooth, the mandible, the palate, and the cranium. We discuss the spatiotemporal regulation of different mechanical cues at both the cellular and tissue scales during craniofacial development and examine how tissue mechanics control various aspects of cell biology and signaling to shape a developing craniofacial organ.
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Affiliation(s)
- Wei Du
- State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases & Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- School of Dentistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Arshia Bhojwani
- School of Dentistry, University of California Los Angeles, Los Angeles, CA, USA
| | - Jimmy K Hu
- School of Dentistry, University of California Los Angeles, Los Angeles, CA, USA.
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA, USA.
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5
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The role of postnatal estrogen deficiency on cranium dimensions. Clin Oral Investig 2020; 25:3249-3255. [PMID: 33099705 DOI: 10.1007/s00784-020-03655-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 10/20/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVES The aim of this study was investigate the cranium dimensions of adult female rats, who suffered estrogen deficiency during the prepubertal stage, to assess the impact of estrogen deficiency on craniofacial morphology. MATERIAL AND METHODS Twenty-two female Wistar rats were divided into ovariectomy (OVX) (n = 11) and sham-operated control (n = 11) groups. Bilateral ovariectomy were performed in both groups at 21 days old (prepubertal stage), and rats were euthanized at an age of 63 days (post-pubertal stage). Micro-CT scans were performed with rat skulls, and the cranium morphometric landmark measurements were taken in the dorsal, lateral, and ventral view positions. Differences in measurements between the OVX and sham control groups were assessed using t test with an established alpha error of 5%. RESULTS The measures of the rats' skull showed that the inter-zygomatic arch width and anterior cranial base length were significantly larger in OVX group (p = 0.020 and p = 0.050, respectively), whereas the length of parietal bone was significantly higher in the sham group (p = 0.026). For the remaining measurements no significant differences between groups were detected (p > 0.05). CONCLUSION This study provides evidence that ovariectomized rats had alterations in cranial bone dimensions, demonstrating that estrogens during puberty are important for skull morphology. CLINICAL RELEVANCE To understand the role of estrogen on the postnatal cranium development will impact the clinical diagnose and therapy during childhood and adolescence.
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Brassard C, Merlin M, Guintard C, Monchâtre-Leroy E, Barrat J, Callou C, Cornette R, Herrel A. Interrelations Between the Cranium, the Mandible and Muscle Architecture in Modern Domestic Dogs. Evol Biol 2020. [DOI: 10.1007/s11692-020-09515-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Katz DC, Aponte JD, Liu W, Green RM, Mayeux JM, Pollard KM, Pomp D, Munger SC, Murray SA, Roseman CC, Percival CJ, Cheverud J, Marcucio RS, Hallgrímsson B. Facial shape and allometry quantitative trait locus intervals in the Diversity Outbred mouse are enriched for known skeletal and facial development genes. PLoS One 2020; 15:e0233377. [PMID: 32502155 PMCID: PMC7274373 DOI: 10.1371/journal.pone.0233377] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 05/04/2020] [Indexed: 02/06/2023] Open
Abstract
The biology of how faces are built and come to differ from one another is complex. Discovering normal variants that contribute to differences in facial morphology is one key to untangling this complexity, with important implications for medicine and evolutionary biology. This study maps quantitative trait loci (QTL) for skeletal facial shape using Diversity Outbred (DO) mice. The DO is a randomly outcrossed population with high heterozygosity that captures the allelic diversity of eight inbred mouse lines from three subspecies. The study uses a sample of 1147 DO animals (the largest sample yet employed for a shape QTL study in mouse), each characterized by 22 three-dimensional landmarks, 56,885 autosomal and X-chromosome markers, and sex and age classifiers. We identified 37 facial shape QTL across 20 shape principal components (PCs) using a mixed effects regression that accounts for kinship among observations. The QTL include some previously identified intervals as well as new regions that expand the list of potential targets for future experimental study. Three QTL characterized shape associations with size (allometry). Median support interval size was 3.5 Mb. Narrowing additional analysis to QTL for the five largest magnitude shape PCs, we found significant overrepresentation of genes with known roles in growth, skeletal and facial development, and sensory organ development. For most intervals, one or more of these genes lies within 0.25 Mb of the QTL's peak. QTL effect sizes were small, with none explaining more than 0.5% of facial shape variation. Thus, our results are consistent with a model of facial diversity that is influenced by key genes in skeletal and facial development and, simultaneously, is highly polygenic.
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Affiliation(s)
- David C. Katz
- Department of Cell Biology & Anatomy, Alberta Children’s Hospital Research Institute and McCaig Bone and Joint Institute, Cumming School of Medicine, University of Calgary, AB, Canada
| | - J. David Aponte
- Department of Cell Biology & Anatomy, Alberta Children’s Hospital Research Institute and McCaig Bone and Joint Institute, Cumming School of Medicine, University of Calgary, AB, Canada
| | - Wei Liu
- Department of Cell Biology & Anatomy, Alberta Children’s Hospital Research Institute and McCaig Bone and Joint Institute, Cumming School of Medicine, University of Calgary, AB, Canada
| | - Rebecca M. Green
- Department of Cell Biology & Anatomy, Alberta Children’s Hospital Research Institute and McCaig Bone and Joint Institute, Cumming School of Medicine, University of Calgary, AB, Canada
| | - Jessica M. Mayeux
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, United States of America
| | - K. Michael Pollard
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, United States of America
| | - Daniel Pomp
- Department of Genetics, University of North Carolina School of Medicine, Chapel Hill, NC, United States of America
| | - Steven C. Munger
- The Jackson Laboratory, Bar Harbor, ME, United States of America
| | | | - Charles C. Roseman
- Department of Evolution, Ecology, and Behavior, University of Illinois Urbana Champaign, Urbana, IL, United States of America
| | - Christopher J. Percival
- Department of Anthropology, Stony Brook University, Stony Brook, NY, United States of America
| | - James Cheverud
- Department of Biology, Loyola University Chicago, Chicago, IL, United States of America
| | - Ralph S. Marcucio
- Department of Orthopaedic Surgery, School of Medicine, University of California San Francisco, San Francisco, CA, United States of America
| | - Benedikt Hallgrímsson
- Department of Cell Biology & Anatomy, Alberta Children’s Hospital Research Institute and McCaig Bone and Joint Institute, Cumming School of Medicine, University of Calgary, AB, Canada
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8
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Feigin CY, Newton AH, Pask AJ. Widespread cis-regulatory convergence between the extinct Tasmanian tiger and gray wolf. Genome Res 2019; 29:1648-1658. [PMID: 31533979 PMCID: PMC6771401 DOI: 10.1101/gr.244251.118] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 08/19/2019] [Indexed: 12/18/2022]
Abstract
The extinct marsupial Tasmanian tiger, or thylacine, and the eutherian gray wolf are among the most widely recognized examples of convergent evolution in mammals. Despite being distantly related, these large predators independently evolved extremely similar craniofacial morphologies, and evidence suggests that they filled similar ecological niches. Previous analyses revealed little evidence of adaptive convergence between their protein-coding genes. Thus, the genetic basis of their convergence is still unclear. Here, we identified candidate craniofacial cis-regulatory elements across vertebrates and compared their evolutionary rates in the thylacine and wolf, revealing abundant signatures of convergent positive selection. Craniofacial thylacine-wolf accelerated regions were enriched near genes involved in TGF beta (TGFB) and BMP signaling, both of which are key morphological signaling pathways with critical roles in establishing the identities and boundaries between craniofacial tissues. Similarly, enhancers of genes involved in craniofacial nerve development showed convergent selection and involvement in these pathways. Taken together, these results suggest that adaptation in cis-regulators of TGF beta and BMP signaling may provide a mechanism to explain the coevolution of developmentally and functionally integrated craniofacial structures in these species. We also found that despite major structural differences in marsupial and eutherian brains, accelerated regions in both species were common near genes with roles in brain development. Our findings support the hypothesis that, relative to protein-coding genes, positive selection on cis-regulatory elements is likely to be an essential driver of adaptive convergent evolution and may underpin thylacine-wolf phenotypic similarities.
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Affiliation(s)
- Charles Y Feigin
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia.,Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA
| | - Axel H Newton
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia.,Museums Victoria, Melbourne, Victoria 3053, Australia
| | - Andrew J Pask
- School of BioSciences, The University of Melbourne, Parkville, Victoria 3010, Australia.,Museums Victoria, Melbourne, Victoria 3053, Australia
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'Double-muscling' and pelvic tilt phenomena in rabbits with the cystine-knot motif deficiency of myostatin on exon 3. Biosci Rep 2019; 39:BSR20190207. [PMID: 31072915 PMCID: PMC6527932 DOI: 10.1042/bsr20190207] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 04/18/2019] [Accepted: 05/06/2019] [Indexed: 11/30/2022] Open
Abstract
Gene mutations at different gene sites will produce totally different phenotypes or biological functions in gene-edited animals. An allelic series of mutations in the myostatin (MSTN) gene can cause the ‘double-muscling’ phenotype. Although there have been many studies performed on MSTN-mutant animals, there have been few studies that have investigated the cystine-knot motif in exon 3 of MSTN in rabbits. In the current study, CRISPR/Cas9 sgRNA anchored exon 3 of a rabbit’s MSTN was used to disrupt the cystine-knot motif to change the MSTN construction and cause a loss of its function. Eleven MSTN-KO founder rabbits were generated, and all of them contained biallelic modifications. Various mutational MSTN amino acid sequences of the 11 founder rabbits were modeled to the tertiary structure using the SWISS-MODEL, and the results showed that the structure of the cystine-knot motif of each protein in the founder rabbits differed from the wild-type (WT). The MSTN-KO rabbits displayed an obvious ‘double-muscling’ phenomena, with a 20−30% increase in body weight compared with WT rabbits. In the MSTN-KO rabbits, all of the MSTN−/− rabbits showed teeth dislocation and tongue enlargement, and the percentage of rabbits having pelvic tilt was 0% in MSTN+/+, 0% in MSTN+/−, 77.78% in female MSTN−/− rabbits, and 37.50% in male MSTN−/− rabbits. The biomechanical mechanism of pelvic tilt and teeth dislocation in the MSTN-KO rabbits requires further investigation. These newly generated MSTN-KO rabbits will serve as an important animal model, not only for studying skeletal muscle development, but also for biomedical studies in pelvic tilt correction and craniofacial research.
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10
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Kesterke MJ, Judd MA, Mooney MP, Siegel MI, Elsalanty M, Howie RN, Weinberg SM, Cray JJ. Maternal environment and craniofacial growth: geometric morphometric analysis of mandibular shape changes with in utero thyroxine overexposure in mice. J Anat 2018; 233:46-54. [PMID: 29611183 DOI: 10.1111/joa.12810] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2018] [Indexed: 12/18/2022] Open
Abstract
An estimated 3% of US pregnancies are affected by maternal thyroid dysfunction, with between one and three of every 1000 pregnancies being complicated by overactive maternal thyroid levels. Excess thyroid hormones are linked to neurological impairment and excessive craniofacial variation, affecting both endochondral and intramembranous bone. Using a geometric morphometric approach, this study evaluates the role of in utero thyroxine overexposure on the growth of offspring mandibles in a sample of 241 mice. Canonical variate analysis utilized 16 unilateral mandibular landmarks obtained from 3D micro-computed tomography to assess shape changes between unexposed controls (n = 63) and exposed mice (n = 178). By evaluating shape changes in the mandible among three age groups (15, 20 and 25 days postnatal) and different dosage levels (low, medium and high), this study found that excess maternal thyroxine alters offspring mandibular shape in both age- and dosage-dependent manners. Group differences in overall shape were significant (P < 0.001), and showed major changes in regions of the mandible associated with muscle attachment (coronoid process, gonial angle) and regions of growth largely governed by articulation with the cranial base (condyle) and occlusion (alveolus). These results compliment recent studies demonstrating that maternal thyroxine levels can alter the cranial base and cranial vault of offspring, contributing to a better understanding of both normal and abnormal mandibular development, as well as the medical implications of craniofacial growth and development.
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Affiliation(s)
| | - Margaret A Judd
- Department of Anthropology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Mark P Mooney
- Department of Anthropology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Oral Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Plastic Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Orthodontics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Communication Sciences and Disorders, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Michael I Siegel
- Department of Anthropology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Oral Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Orthodontics, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | | | - R Nicole Howie
- Department of Oral Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
| | - Seth M Weinberg
- Department of Anthropology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.,Department of Oral Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - James J Cray
- Department of Oral Health Sciences, Medical University of South Carolina, Charleston, South Carolina, USA
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11
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The Morphological Grading and Comparison of Sutural Patency Among Cranial Sutures in Dry Human Skulls. J Craniofac Surg 2017; 28:2155-2158. [PMID: 28938334 DOI: 10.1097/scs.0000000000004011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
OBJECTIVE To investigate the degree of fusion (patency) among cranial sutures in human dry skulls in the Anatolia. METHODS One-hundred fifty-eight human dry skulls that were accepted as adults according to the teeth eruption were macroscopically examined and photographed with Canon 400B (55 mm objective). The grades of fusion of coronal, sagittal, and lambdoid were quantitatively analyzed by using the modified grading scale. According to the extent of patency, the sutures were graded as grade-0 (open), grade-1 (fused but not obliterated), grade-2 (50%< obliterated), grade-3 (50% > obliterated), and grade-4 (100% obliterated). The authors determined and compared the rate for each grade of sutural patency on coronal, sagittal, and lambdoid sutures. RESULTS The cranial sutures of 4 cranii (4/158; 2.53%) had grade-4 fusion, whereas there were no any cranii with sutures of grade-0 fusion. The number of each grade of fusion among cranial sutures of 158 skulls, in descending order, was as follows: 171 (grade-3), 145 (grade-1), 133 (grade-2), and 25 (grade-4). The grade-4 fusion was significantly less observed than the others. The grade-1 and grade-4 fusion of lambdoid sutures were established as the most (66/41.8%) and least (5/3.2%) common fusions among cranial sutures, respectively. The frequencies of each grade of fusion for each cranial suture were determined in a descending order: coronal (grade-3 > 2 > 1 > 4), sagittal (grade-3 > 2 > 1 > 4), and lambdoid sutures (grade-1 > 3 > 2 > 4). The frequency of grade-1 fusion of lambdoid suture (66/41.8%) was significantly different when compared with coronal (39/24.7%) and sagittal sutures (40/25.3%), respectively. CONCLUSION The grades of fusion (or sutural patency) vary among cranial sutures.
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Spassov A, Toro-Ibacache V, Krautwald M, Brinkmeier H, Kupczik K. Congenital muscle dystrophy and diet consistency affect mouse skull shape differently. J Anat 2017; 231:736-748. [PMID: 28762259 DOI: 10.1111/joa.12664] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/31/2017] [Indexed: 12/17/2022] Open
Abstract
The bones of the mammalian skull respond plastically to changes in masticatory function. However, the extent to which muscle function affects the growth and development of the skull, whose regions have different maturity patterns, remains unclear. Using muscle dissection and 3D landmark-based geometric morphometrics we investigated the effect of changes in muscle function established either before or after weaning, on skull shape and muscle mass in adult mice. We compared temporalis and masseter mass and skull shape in mice with a congenital muscle dystrophy (mdx) and wild type (wt) mice fed on either a hard or a soft diet. We found that dystrophy and diet have distinct effects on the morphology of the skull and the masticatory muscles. Mdx mice show a flattened neurocranium with a more dorsally displaced foramen magnum and an anteriorly placed mandibular condyle compared with wt mice. Compared with hard diet mice, soft diet mice had lower masseter mass and a face with more gracile features as well as labially inclined incisors, suggesting reduced bite strength. Thus, while the early-maturing neurocranium and the posterior portion of the mandible are affected by the congenital dystrophy, the late-maturing face including the anterior part of the mandible responds to dietary differences irrespective of the mdx mutation. Our study confirms a hierarchical, tripartite organisation of the skull (comprising neurocranium, face and mandible) with a modular division based on development and function. Moreover, we provide further experimental evidence that masticatory loading is one of the main environmental stimuli that generate craniofacial variation.
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Affiliation(s)
- Alexander Spassov
- Department of Orthodontics, University Medicine Greifswald, Greifswald, Germany.,Institute of Pathophysiology, University Medicine Greifswald, Karlsburg, Germany
| | - Viviana Toro-Ibacache
- Facultad de Odontología, Universidad de Chile, Santiago de Chile, Chile.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Mirjam Krautwald
- Institute of Pathophysiology, University Medicine Greifswald, Karlsburg, Germany
| | - Heinrich Brinkmeier
- Institute of Pathophysiology, University Medicine Greifswald, Karlsburg, Germany
| | - Kornelius Kupczik
- Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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Mayne RJ, van der Poel C, Woods MG, Lynch GS. Skeletal effects of the alteration of masseter muscle function. AUSTRALASIAN ORTHODONTIC JOURNAL 2015. [DOI: 10.21307/aoj-2020-154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Abstract
Aim
To investigate the effects of muscle denervation and the introduction of the β2-adrenoceptor agonist, formoterol, on the relationship between muscles and underlying skeletal growth.
Method
Thirty-one (4-week-old) male Sprague-Dawley rats were assigned to four groups: Surgical Sham; Denervated; Denervated +β2-agonist; and β2-agonist only. The Surgical Sham group had the left masseteric nerve exposed but not sectioned. Both of the denervated groups had the left masseteric nerve exposed and sectioned. The groups receiving the β2-agonist had formoterol directly injected into the left masseter muscle every three days for eight weeks. Sixteen angular and linear skeletal measurements were assessed in the overall craniofacial region and the mandible via standardised digital radiography in three views: lateral head, submento-vertex and right and left disarticulated hemi-mandibles.
Results
The findings indicated that, following surgical denervation of the masseter muscle, there were significant changes in the muscle and in the subsequent development of the underlying skeletal structures. The post-surgical changes were largely offset by the administration of a β2-agonist, formoterol, which attenuated muscle atrophy. However, the administration of the β2-agonist only, without surgical denervation, did not lead to changes in skeletal facial form.
Conclusions
Denervation atrophy of the masseter muscle results in statistically significant changes in the development of the underlying skeleton. The changes, however, are localised to areas of muscle attachment. The administration of the β2-agonist, formoterol, despite its effect on muscle anabolism, does not have a significant effect on underlying skeletal growth.
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Affiliation(s)
- Robert J. Mayne
- * Orthodontic Unit , University of Melbourne , Melbourne , Australia
| | - Chris van der Poel
- † Department of Physiology , University of Melbourne , Melbourne , Australia
| | - Michael G. Woods
- + Oral and Maxillofacial Surgery Unit , Melbourne Health and Royal Melbourne Hospital , Melbourne , Australia
| | - Gordon S. Lynch
- † Department of Physiology , University of Melbourne , Melbourne , Australia
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Williams SH, Lozier NR, Montuelle SJ, de Lacalle S. Effect of Postnatal Myostatin Inhibition on Bite Mechanics in Mice. PLoS One 2015; 10:e0134854. [PMID: 26252892 PMCID: PMC4529299 DOI: 10.1371/journal.pone.0134854] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 07/14/2015] [Indexed: 11/25/2022] Open
Abstract
As a negative regulator of muscle size, myostatin (Mstn) impacts the force-production capabilities of skeletal muscles. In the masticatory system, measures of temporalis-stimulated bite forces in constitutive myostatin KOs suggest an absolute, but not relative, increase in jaw-muscle force. Here, we assess the phenotypic and physiologic impact of postnatal myostatin inhibition on bite mechanics using an inducible conditional KO mouse in which myostatin is inhibited with doxycycline (DOX). Given the increased control over the timing of gene inactivation in this model, it may be more clinically-relevant for developing interventions for age-associated changes in the musculoskeletal system. DOX was administered for 12 weeks starting at age 4 months, during which time food intake was monitored. Sex, age and strain-matched controls were given the same food without DOX. Bite forces were recorded just prior to euthanasia after which muscle and skeletal data were collected. Food intake did not differ between control or DOX animals within each sex. DOX males were significantly larger and had significantly larger masseters than controls, but DOX and control females did not differ. Although there was a tendency towards higher absolute bite forces in DOX animals, this was not significant, and bite forces normalized to masseter mass did not differ. Mechanical advantage for incisor biting increased in the DOX group due to longer masseter moment arms, likely due to a more anteriorly-placed masseter insertion. Despite only a moderate increase in bite force in DOX males and none in DOX females, the increase in masseter mass in males indicates a potentially positive impact on jaw muscles. Our data suggest a sexual dimorphism in the role of mstn, and as such investigations into the sex-specific outcomes is warranted.
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Affiliation(s)
- Susan H. Williams
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, Ohio, United States of America
- * E-mail:
| | - Nicholas R. Lozier
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, Ohio, United States of America
| | - Stéphane J. Montuelle
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, Ohio, United States of America
| | - Sonsoles de Lacalle
- Department of Biomedical Sciences, Ohio University Heritage College of Osteopathic Medicine, Athens, Ohio, United States of America
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Jeffery N, Mendias C. Endocranial and masticatory muscle volumes in myostatin-deficient mice. ROYAL SOCIETY OPEN SCIENCE 2014; 1:140187. [PMID: 26064569 PMCID: PMC4448778 DOI: 10.1098/rsos.140187] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 08/15/2014] [Indexed: 06/04/2023]
Abstract
Structural and functional trade-offs are integral to the evolution of the mammalian skull and its development. This paper examines the potential for enlargement of the masticatory musculature to limit the size of the endocranial cavity by studying a myostatin-deficient mouse model of hypermuscularity (MSTN-/-). The study tests the null prediction that the larger MSTN-/- mice have larger brains compared with wild-type (WT) mice in order to service the larger muscles. Eleven post-mortem MSTN-/- mice and 12 WT mice were imaged at high resolution using contrast enhanced micro-CT. Masticatory muscle volumes (temporalis, masseter, internal and external pterygoids) and endocranial volumes were measured on the basis of two-dimensional manual tracings and the Cavalieri principle. Volumes were compared using Kruskal-Wallis and Student's t-tests. Results showed that the masticatory muscles of the MSTN-/- mice were significantly larger than in the WT mice. Increases were in the region of 17-36% depending on the muscle. Muscles increased in proportion to each other, maintaining percentages in the region of 5, 10, 21 and 62% of total muscle volume for the external ptyergoid, internal pterygoid, temporalis and masseter, respectively. Kruskal-Wallis and t-tests demonstrated that the endocranial volume was significantly larger in the WT mice, approximately 16% larger on average than that seen in the MSTN-/- mice. This comparative reduction of MSTN-/- endocranial size could not be explained in terms of observer bias, ageing, sexual dimorphism or body size scaling. That the results showed a reduction of brain size associated with an increase of muscle size falsifies the null prediction and lends tentative support to the view that the musculature influences brain growth. It remains to be determined whether the observed effect is primarily physical, nutritional, metabolic or molecular in nature.
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Affiliation(s)
- Nathan Jeffery
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Sherrington Building, Ashton Street, Liverpool L69 3GE, UK
| | - Christopher Mendias
- Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA
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Liu J, Jin ZL, Li Q. Effect of occlusal hypofunction and its recovery on the three-dimensional architecture of mandibular alveolar bone in growing rats. J Surg Res 2014; 193:229-36. [PMID: 25224274 DOI: 10.1016/j.jss.2014.07.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Revised: 06/19/2014] [Accepted: 07/09/2014] [Indexed: 11/15/2022]
Abstract
BACKGROUD Normal occlusion is very important for physiological structure of mandible. However, the details of influences of occlusal hypofunction and its recovery on the three-dimensional architecture of mandibular alveolar bone in growing rats are still lacking. MATERIALS AND METHODS Forty-eight growing male Sprague-Dawley rats were randomly divided into normal (n = 24), hypofunctional (n = 12), and recovery (n = 12) groups. The hypofunction group was developed by inserting a bite-raising appliance between the maxillary and mandibular incisors of the rats. Two weeks after insertion, the appliance was removed to result in the recovery group; the experiment continued for two additional weeks. The experimental animals and control animals were killed weekly. In addition to measuring the body weight and masseter muscle weight of the rats, the histomorphology and microstructure of the mandibular alveolar bone were scanned using microcomputed tomography. RESULTS A lighter masseter muscle and a higher and narrower alveolar process were observed in the hypofunction group compared with the control animals (P < 0.05). Mandibular remodeling also occurred in the hypofunctional group, as demonstrated by a smaller trabecular cross-sectional area, looser trabecular bone, decreased bone volume fraction, trabecular thickness, trabecular number, and increased bone surface density and trabecular separation, especially at week 2 (P < 0.05). After removing the anterior bite-opening appliance, the altered masseter muscle weight and architecture of the mandibular alveolar bone were gradually reversed and reached normal levels at the end of the experiment (P > 0.05). CONCLUSIONS A loss of occlusal stimuli can lead into mandibular alveolar bone remodeling, and the recovery of occlusion can restore the altered mandibular architecture in growing rats.
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Affiliation(s)
- Jia Liu
- State Key Laboratory of Military Stomatology, Department of Orthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi Province, People's Republic of China
| | - Zuo-lin Jin
- State Key Laboratory of Military Stomatology, Department of Orthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi Province, People's Republic of China.
| | - Qiang Li
- State Key Laboratory of Military Stomatology, Department of General Dentistry & Emergency, School of Stomatology, Fourth Military Medical University, Xi'an, Shaanxi Province, People's Republic of China.
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Abstract
Bone and muscle mass are highly correlated. In part, this is a consequence of both tissues sharing common genetic determinants. In addition, both tissues are responsive to their mechanical environments. New genetic tools in mice will allow genes of interest to be inactivated in experimentally defined contexts, thus allowing investigators to distinguish direct effects on each tissue from physiological responses to a primary phenotype in the other.
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Roderer B, Tsagkari E, Gredes T, Dominiak M, Gedrange T, Kunert-Keil C. WITHDRAWN: Age-dependent muscle dystrophy related changes of craniofacial morphology in mdx mice. Arch Oral Biol 2013:S0003-9969(13)00217-3. [PMID: 23938151 DOI: 10.1016/j.archoralbio.2013.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/04/2013] [Accepted: 07/05/2013] [Indexed: 11/21/2022]
Abstract
This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.
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Affiliation(s)
- Beate Roderer
- Department of Orthodontics, Carl Gustav Carus Campus, Technische Universität Dresden, Fetscherstr. 74, D-01307 Dresden, Germany
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Baverstock H, Jeffery NS, Cobb SN. The morphology of the mouse masticatory musculature. J Anat 2013; 223:46-60. [PMID: 23692055 PMCID: PMC4487762 DOI: 10.1111/joa.12059] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/11/2013] [Indexed: 01/07/2023] Open
Abstract
The mouse has been the dominant model organism in studies on the development, genetics and evolution of the mammalian skull and associated soft-tissue for decades. There is the potential to take advantage of this well studied model and the range of mutant, knockin and knockout organisms with diverse craniofacial phenotypes to investigate the functional significance of variation and the role of mechanical forces on the development of the integrated craniofacial skeleton and musculature by using computational mechanical modelling methods (e.g. finite element and multibody dynamic modelling). Currently, there are no detailed published data of the mouse masticatory musculature available. Here, using a combination of micro-dissection and non-invasive segmentation of iodine-enhanced micro-computed tomography, we document the anatomy, architecture and proportions of the mouse masticatory muscles. We report on the superficial masseter (muscle, tendon and pars reflecta), deep masseter, zygomaticomandibularis (anterior, posterior, infraorbital and tendinous parts), temporalis (lateral and medial parts), external and internal pterygoid muscles. Additionally, we report a lateral expansion of the attachment of the temporalis onto the zygomatic arch, which may play a role in stabilising this bone during downwards loading. The data presented in this paper now provide a detailed reference for phenotypic comparison in mouse models and allow the mouse to be used as a model organism in biomechanical and functional modelling and simulation studies of the craniofacial skeleton and particularly the masticatory system.
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Affiliation(s)
- Hester Baverstock
- Centre for Anatomical and Human Sciences, Hull York Medical School, University of Hull, Hull, UK.
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Sciote JJ, Raoul G, Ferri J, Close J, Horton MJ, Rowlerson A. Masseter function and skeletal malocclusion. ACTA ACUST UNITED AC 2013; 114:79-85. [PMID: 23838245 DOI: 10.1016/j.revsto.2013.01.015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Revised: 11/14/2012] [Accepted: 01/28/2013] [Indexed: 01/18/2023]
Abstract
The aim of this work is to review the relationship between the function of the masseter muscle and the occurrence of malocclusions. An analysis was made of the masseter muscle samples from subjects who underwent mandibular osteotomies. The size and proportion of type-II fibers (fast) decreases as facial height increases. Patients with mandibular asymmetry have more type-II fibers on the side of their deviation. The insulin-like growth factor and myostatin are expressed differently depending on the sex and fiber diameter. These differences in the distribution of fiber types and gene expression of this growth factor may be involved in long-term postoperative stability and require additional investigations. Muscle strength and bone length are two genetically determined factors in facial growth. Myosin 1H (MYOH1) is associated with prognathia in Caucasians. As future objectives, we propose to characterize genetic variations using "Genome Wide Association Studies" data and their relationships with malocclusions.
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Affiliation(s)
- J J Sciote
- Department of Orthodontics, Temple University, Philadelphia, PA 19104, USA.
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22
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Tsai C, Lin Y, Su B, Yang L, Chiu W. Masseter muscle fibre changes following reduction of masticatory function. Int J Oral Maxillofac Surg 2012; 41:394-9. [DOI: 10.1016/j.ijom.2011.10.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 07/11/2011] [Accepted: 10/18/2011] [Indexed: 10/15/2022]
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Postnatal Cranial Development in Papionin Primates: An Alternative Model for Hominin Evolutionary Development. Evol Biol 2012. [DOI: 10.1007/s11692-011-9153-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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Sciote JJ, Horton MJ, Rowlerson AM, Ferri J, Close JM, Raoul G. Human masseter muscle fiber type properties, skeletal malocclusions, and muscle growth factor expression. J Oral Maxillofac Surg 2011; 70:440-8. [PMID: 21821327 DOI: 10.1016/j.joms.2011.04.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 04/07/2011] [Accepted: 04/08/2011] [Indexed: 11/24/2022]
Abstract
PURPOSE We identified masseter muscle fiber type property differences in subjects with dentofacial deformities. PATIENTS AND METHODS Samples of masseter muscle were collected from 139 young adults during mandibular osteotomy procedures to assess mean fiber areas and percent tissue occupancies for the 4 fiber types that comprise the muscle. Subjects were classified into 1 of 6 malocclusion groups based on the presence of a skeletal Class II or III sagittal dimension malocclusion and either a skeletal open, deep, or normal bite vertical dimension malocclusion. In a subpopulation, relative quantities of the muscle growth factors IGF-I and GDF-8 gene expression were quantified by real-time polymerase chain reaction. RESULTS Fiber properties were not different in the sagittal malocclusion groups, but were very different in the vertical malocclusion groups (P ≤ .0004). There were significant mean fiber area differences for type II (P ≤ .0004) and type neonatal-atrial (P = .001) fiber types and for fiber percent occupancy differences for both type I-II hybrid fibers and type II fibers (P ≤ .0004). Growth factor expression differed by gender for IGF-I (P = .02) and GDF-8 (P < .01). The ratio of IGF-I:GDF-8 expression associates with type I and II mean fiber areas. CONCLUSION Fiber type properties are very closely associated with variations in vertical growth of the face, with statistical significance for overall comparisons at P ≤ .0004. An increase in masseter muscle type II fiber mean fiber areas and percent tissue occupancies is inversely related to increases in vertical facial dimension.
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Cray J, Kneib J, Vecchione L, Byron C, Cooper GM, Losee JE, Siegel MI, Hamrick MW, Sciote JJ, Mooney MP. Masticatory hypermuscularity is not related to reduced cranial volume in myostatin-knockout mice. Anat Rec (Hoboken) 2011; 294:1170-7. [PMID: 21618442 DOI: 10.1002/ar.21412] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Revised: 03/03/2011] [Accepted: 04/18/2011] [Indexed: 12/19/2022]
Abstract
It has been suggested recently that masticatory muscle size reduction in humans resulted in greater encephalization through decreased compressive forces on the cranial vault. Following this logic, if masticatory muscle size were increased, then a reduction in brain growth should also occur. This study was designed to test this hypothesis using a myostatin (GDF-8) knockout mouse model. Myostatin is a negative regulator of skeletal muscle growth, and individuals lacking this gene show significant hypermuscularity. Sixty-two [32 wild-type (WT) and 30 GDF-8 -/- knockout], 1, 28, 56, and 180-day-old CD-1 mice were used. Body and masseter muscle weights were collected following dissection and standardized lateral and dorsoventral cephalographs were obtained. Cephalometric landmarks were identified on the radiographs and cranial volume was calculated. Mean differences were assessed using a two-way ANOVA. KO mice had significantly greater body and masseter weights beginning at 28 days compared with WT controls. No significant differences in cranial volumes were noted between KO and WT. Muscle weight was not significantly correlated with cranial volume in 1, 28, or 180-day-old mice. Muscle weights exhibited a positive correlation with cranial volume at 56 days. Results demonstrate that masticatory hypermuscularity is not associated with reduced cranial volume. In contrast, there is abundant data demonstrating the opposite, brain growth determines cranial vault growth and masticatory apparatus only affects ectocranial morphology. The results presented here do not support the hypothesis that a reduction in masticatory musculature relaxed compressive forces on the cranial vault allowing for greater encephalization.
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Affiliation(s)
- James Cray
- Division of Plastic and Reconstructive Surgery, Department of Surgery, University of Pittsburgh, Pennsylvania 15201, USA.
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26
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Green DJ, Hamrick MW, Richmond BG. The effects of hypermuscularity on shoulder morphology in myostatin-deficient mice. J Anat 2011; 218:544-57. [PMID: 21332716 DOI: 10.1111/j.1469-7580.2011.01351.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Mechanical loads, particularly those generated by skeletal muscle, play a significant role in determining long-bone shape and strength, but it is less clear how these loads influence the morphology of flat bones like the scapula. While scapular morphology has been shown to vary with locomotor mode in mammals, this study seeks to better understand whether genetically modified muscle size can influence scapular shape in the absence of significant locomotor differences. The soft- and hard-tissue morphological characteristics were examined in 11 hypermuscular, mutant (myostatin-deficient), 20 heterozygote, and 15 wild-type mouse shoulders. Body mass did not significantly differ among the genotype groups, but homozygous mutant and heterozygote mice had significantly larger shoulder muscles than wild-type mice. Mutant mice also differed significantly from the wild-type controls in several aspects of scapular size and shape, including glenohumeral joint orientation, total scapular length, superior border length, and supraspinous and infraspinous fossa length. Conversely, several traits describing superoinferior scapular breadth measures (e.g. total breadth and dorsal scapular fossa breadth) did not significantly differ between mutant and wild-type mice. Since the intrinsic musculature of the scapula is oriented in a mediolateral fashion, it follows that mediolaterally configured hard-tissue features like scapular length were most distinct among genotype groups. As had been noted previously with long bones, this study demonstrates that genetically enhanced muscle size has marked effects on the morphological characteristics of the shoulder.
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Affiliation(s)
- David J Green
- Department of Anthropology, The George Washington University, 2110 G St., NW, Washington, DC 20052, USA.
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Cray J, Mooney MP, Siegel MI. Cranial Suture Biology of the Aleutian Island Inhabitants. Anat Rec (Hoboken) 2011; 294:676-82. [DOI: 10.1002/ar.21345] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Revised: 12/15/2010] [Accepted: 12/22/2010] [Indexed: 11/08/2022]
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28
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Barton ER, Crowder C. Growth Factor Targets for Orthodontic Treatments. Semin Orthod 2010. [DOI: 10.1053/j.sodo.2010.02.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Cray J, Mooney MP, Siegel MI. Timing of Ectocranial Suture Activity in Pan troglodytes as Related to Cranial Volume and Dental Eruption. Anat Rec (Hoboken) 2010; 293:1289-96. [DOI: 10.1002/ar.21167] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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31
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Vecchione L, Miller J, Byron C, Cooper GM, Barbano T, Cray J, Losee JE, Hamrick MW, Sciote JJ, Mooney MP. Age-related changes in craniofacial morphology in GDF-8 (myostatin)-deficient mice. Anat Rec (Hoboken) 2010; 293:32-41. [PMID: 19899116 DOI: 10.1002/ar.21024] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
It is well recognized that masticatory muscle function helps determine morphology, although the extent of function on final form is still debated. GDF-8 (myostatin), a transcription factor is a negative regulator of skeletal muscle growth. A recent study has shown that mice homozygous for the myostatin mutation had increased muscle mass and craniofacial dysmorphology in adulthood. However, it is unclear whether such dysmorphology is present at birth. This study examines the onset and relationship between hypermuscularity and craniofacial morphology in neonatal and adult mice with GDF-8 deficiency. Fifteen (8 wild-type and 7 GDF-8 -/-), 1-day-old and 16 (9 wt and 7 GDF-8 -/-), 180-day-old male CD-1 mice were used. Standardized radiographs were taken of each head, scanned, traced, and cephalometric landmarks identified. Significant mean differences were assessed using a group x age, two-way ANOVA. Myostatin-deficient mice had significantly (P < 0.01) smaller body and masseter muscle weights and craniofacial skeletons at 1 day of age and significantly greater body and masseter muscle weights at 180 days of age compared to controls. Myostatin-deficient mice showed significantly (P < 0.001) longer and "rocker-shaped" mandibles and shorter and wider crania compared to controls at 180 days. Significant correlations were noted between masseter muscle weight and all cephalometric measurements in 180-day-old Myostatin-deficient mice. Results suggest that in this mouse model, there may be both early systemic skeletal growth deficiencies and later compensatory changes from hypermuscularity. These findings reiterate the role that masticatory muscle function plays on the ontogeny of the cranial vault, base, and most notably the mandible.
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Affiliation(s)
- Lisa Vecchione
- Pittsburgh Cleft-Craniofacial Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA
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32
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Effects on craniofacial growth and development of unilateral botulinum neurotoxin injection into the masseter muscle. Am J Orthod Dentofacial Orthop 2009; 135:142.e1-6; discussion 142-3. [PMID: 19201315 DOI: 10.1016/j.ajodo.2008.06.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2008] [Revised: 06/01/2008] [Accepted: 06/01/2008] [Indexed: 11/24/2022]
Abstract
INTRODUCTION The effects of botulinum neurotoxin type A (BoNT/A) on masseter muscles, when injected for cosmetic purposes (volumetric reduction) or treatment of excessive muscle activity (bruxism), have been investigated. However, the full anatomic effects of treatment are not known, particularly with respect to the mandible and relevant anthropometric measurements. The intent of this study was to use unilaterial BoNT/A injections to induce localized masseter atrophy and paresis and then to measure the effects of muscle influence on craniofacial growth and development. METHODS Growing male Wistar rats, 30 days old, were studied. The experimental group consisted of 8 rats. One side of the masseter muscle was injected with BoNT/A and the other side of the masseter muscle was injected with saline. The side with BoNT/A belonged to 1 group and the side with saline was the sham group. Three rats without injections was the control. After 45 days, the masseter muscles were dissected and weighed. Dry skulls were prepared, and anthropometric measurements determined. RESULTS One-way ANOVA showed that the animals maintained their weight in both groups; however, the muscles injected with BoNT/A were smaller than the sham or control muscles. Anthropometric measurements of the bony structures attached to the masseter muscle showed a significant treatment effect. CONCLUSIONS After localized masseter muscle atrophy induced by BoNT/A injection, alterations of craniofacial bone growth and development were seen. The results agree with the functional matrix theory that soft tissues regulate bone growth.
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Byron CD, Maness H, Yu JC, Hamrick MW. Enlargement of the temporalis muscle and alterations in the lateral cranial vault. Integr Comp Biol 2008; 48:338-44. [PMID: 21669796 DOI: 10.1093/icb/icn020] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The purpose of this study was to test the hypothesis that increased masticatory muscle accompanied morphologic changes in the temporal bone and squamosal suture. Ten mice deficient for the protein myostatin (Mstn -/-) had significantly increased skeletal muscle mass and were compared with nine controls (Mstn +/+). Variables measured include linear and areal metrics describing temporal size and temporal bone shape as well as the extent of the area of the squamosal suture that overlaps, or bevels, with parietal bones. Mstn-/- mice showed significantly larger temporalis muscles. Their temporal bones showed significantly decreased size as well as decreased beveling of the squamosal suture. These decreases were absolute as well as relative and were not restricted to either vertical or horizontal axes. The increased masticatory musculature of Myostatin-null mice had a shrinking effect on the temporal aspect of the cranium. These results are inconsistent with the interpretation that increased temporalis mass induces morphologic changes in temporal bone that compensate for putative increases in compressive forces transduced at this region. Rather than increase in the area of overlap between two calvarial bones, potential increase in biomechanical loading along the temporal squama led to a smaller bevel which would presumably weaken this joint. It is unclear why this is so. Either compressive forces are not anabolic to suture beveling or they do upregulate growth of the suture bevel, with compression not being the primary loading regime at this suture.
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Affiliation(s)
- Craig D Byron
- *Department of Biology, Mercer University, Macon, GA 31201; Department of Orthodontics, School of Dentistry, Medical College of Georgia, Augusta, GA 30912; Department of Surgery, Section of Plastics, Medical College of Georgia, Augusta, GA 30912; Department of Cell Biology and Anatomy, Medical College of Georgia, Augusta, GA 30912
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