Morphology of the mandibular canal and the angulation between the mandibular and mental canals in dry skulls.
TL;DR: The findings show that the internal courses of theMandibular and mental canals are interrelated and indicated that the course and morphology of the mandibular canal are inter related with external mandibul morphology.
Abstract: The aim of this study was to analyse the correlation between external and internal mandibular morphology in adult or adolescent normal anthropological mandibles. Lateral radiographs of 31 symmetrical mandibles were analysed. The external morphology was defined by the gonial and beta-angles. In order to analyse internal morphology, a metallic pin was placed in the mental canal on the left side before radiography. The angle between the mental and the mandibular canals was termed the 'mental angle' and that expressing the curvature of the mandibular canal, the 'mandibular angle'. Spearman correlation analysis was used to investigate the relationships between the angles. Internal morphology: a statistically significant correlation was found between the mental and mandibular angles (correlation coefficient: -0.60, P=0.0004). When the mental angle was narrow, the mandibular angle tended to be wide, while a wide mental angle was interrelated with a narrow mandibular angle. External morphology: a statistically significant correlation was found between the mandibular and gonial angles (correlation coefficient: 0.57, P=0.0009). A weaker correlation was also found between the mandibular and beta-angles. The findings show that the internal courses of the mandibular and mental canals are interrelated. They also indicated that the course and morphology of the mandibular canal are interrelated with external mandibular morphology.
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TL;DR: The data show that excessive tooth wear eventually leads to a breakdown of the normal remodeling mechanisms, resulting in dentognathic pathologies, tooth loss, and loss of masticatory function, which is unlikely to have limited the life span of early Homo.
Abstract: The Plio-Pleistocene hominin sample from Dmanisi (Georgia), dated to 1.77 million years ago, is unique in offering detailed insights into patterns of morphological variation within a paleodeme of early Homo. Cranial and dentoalveolar morphologies exhibit a high degree of diversity, but the causes of variation are still relatively unexplored. Here we show that wear-related dentoalveolar remodeling is one of the principal mechanisms causing mandibular shape variation in fossil Homo and in modern human hunter–gatherer populations. We identify a consistent pattern of mandibular morphological alteration, suggesting that dental wear and compensatory remodeling mechanisms remained fairly constant throughout the evolution of the genus Homo. With increasing occlusal and interproximal tooth wear, the teeth continue to erupt, the posterior dentition tends to drift in a mesial direction, and the front teeth become more upright. The resulting changes in dentognathic size and shape are substantial and need to be taken into account in comparative taxonomic analyses of isolated hominin mandibles. Our data further show that excessive tooth wear eventually leads to a breakdown of the normal remodeling mechanisms, resulting in dentognathic pathologies, tooth loss, and loss of masticatory function. Complete breakdown of dentognathic homeostasis, however, is unlikely to have limited the life span of early Homo because this effect was likely mediated by the preparation of soft foods.
34 citations
Cites methods from "Morphology of the mandibular canal ..."
...Linear and angular measurements of dentoalveolar remodeling were taken with reference to themandibular canal, as this structure remains stable during growth and aging (68, 69)....
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TL;DR: Bjork's implant studies have contributed much to understanding facial-skeletal growth; however, this study suggests that their utilization as a tool in classifying extreme skeletal patterns requires careful evaluation of all the parameters involved.
Abstract: Backround: Morphological indicators within the cranium for prediction of mandibular growth patterns as reported by Bjork are: (1) inclination of the condylar head (ICH), (2) curvature of mandibular canal (CMC), (3) shape of the lower border of the mandible and specifically depth of the antegonial notch (AN), (4) inclination of the symphysis (ISY), (5) interincisal angle (IIA), (6) intermolar angle (IMA), and (7) lower anterior face height (LAFH). The purpose of this study was to examine the association of these indicators as they relate to extreme skeletal patterns observed in skeletally mature subjects.
Materials: The pre-treatment lateral cephalometric radiographs of 395 post-growth subjects were randomly selected from the archives of a university orthodontic department. These were divided in three groups according to their MP-SN angle [normal: 28–36degrees (G1), hypodivergent: ≤26degrees (G2), hyperdivergent: ≥38degrees (G3)].
Results: It was found that only LAFH was correlated to age across all groups. However, within G1, G2, and G3, and between genders, it was found that there were statistically significant differences for all indicators in relation to age, except IMA ( P > 0.05). In addition, ISY and IMA had a predictive value lower than the chance level (0.5).
Conclusion: Bjork’s implant studies have contributed much to understanding facial–skeletal growth; however, this study suggests that their utilization as a tool in classifying extreme skeletal patterns requires careful evaluation of all the parameters involved.
10 citations
TL;DR: The study indicates that the direction of the infraorbital canal in frontal view reflects the transversal growth of the maxilla, which might explain the different inclination of ectopic canines.
Abstract: Objective. The purpose of this study was to analyze the correlation between direction of the infraorbital canal and maxillary width on frontal radiographs of dry human skulls. Material and methods. Forty-two symmetrical, dry human skulls (late adolescence and adult) with no dental or skeletal anomalies. Frontal radiographs were taken of each skull placed in the Frankfort horizontal plane, with a radiopaque marker in the infraorbital canal. The maxillary transversal growth pattern was expressed as the infraorbital transversal angle (IOt) formed between a line through the contour of the bilateral orbita (lo) and a line parallel to the infraorbital marker. Three cephalometric widths were measured on the skulls, two anteriorly (the width of the piriform aperture (AP) and the interorbital width (IO)) and one posteriorly (the palatal width (PW)). A general linear model was used for statistical analysis. Results. The direction of the infraorbital canal (66.088, 95% CI: 62.5369.64) depended on the transversal growth: an increased PW of 1 mm resulted in a decreased IOt of 1.848 (p0.041); an increase in IO of 1 mm resulted in an increased IOt of 2.248 (p0.017); and an increased AP of 1 mm resulted in a decreased IOt of 3.308 (p0.066). Conclusions. The study indicates that the direction of the infraorbital canal in frontal view reflects the transversal growth of the maxilla. A wide maxilla posteriorly resulted in a small infraorbital transversal angle. These findings might explain the different inclination of ectopic canines.
8 citations
Cites background from "Morphology of the mandibular canal ..."
...In the mandible, Pálsson & Kjær [6] have shown that direction of the mental canal is closely associated with mandibular growth and morphology....
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...Furthermore, Pálsson & Kjær [6] demonstrated that the direction of the mental canal on dry skulls is closely associated with the shape of the mandibular canal....
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...Pálsson & Kjær [6] demonstrated a close relationship between mandibular morphology and direction of the mental canal....
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Journal Article•
TL;DR: The morphological knowledge of these foramina is important as they transmit the branches of the nerves which supply the roots of the teeth.
Abstract: Conclusion: In the current study, the incidence rate of the accessory mandibular foramina was 16.4%. The morphological knowledge of these foramina is important as they transmit the branches of the nerves which supply the roots of the teeth. The local anaesthetic drug which is given in this region may fail if these nerves or their branches pass through the accessory foramina. B.V. MurliManju, latha V. PraBhu, M.D. PraMeela, C. MohaMMeD ashraf, ashWin KrishnaMurthy, C. Ganesh KuMar a na to m y
7 citations
Cites background from "Morphology of the mandibular canal ..."
...[19] Palsson SR, Kjaer I: Morphology of the mandibular canal and the angulation between the mandibular and mental canals in dry skulls....
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...It was suggested that the morphology of the MF should be included in the orthodontic and anthropological evaluation of normal and pathological mandibles [19]....
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TL;DR: The findings of this study showed that the position and curvature of the mandibular canal reflect the outer morphology and growth pattern of themandible.
Abstract: Objectives To evaluate the position and curvature of mandibular canal in relation to mandibular plane in horizontal (HG), average (AG) and vertical (VG) growth patterns Methods 100 lateral cephalograms were screened & analysed from amongst patient's records available in the institution The growth pattern was assessed by FMA angle, Y-Axis, SN-Go-Gn angle and Jaraback's ratio, on the basis of these values, a sample was selected of 20 lateral cephalographs each in horizontal, average and vertical growth pattern Rickett's Xi point was identified and mandibular canal was traced on each lateral cephalogram using Xi point which denotes the origin of mandibular canal Distance between, Gonial point to Xi point, Mental foramen to mandibular plane (M F –M), Mandibular foramen to pterygoid vertical (X i –PTV) and from deepest point on mandibular canal to mandibular plane (Mc–M) were measured to evaluate the position and curvature of mandibular canal in different growth patterns Results It was observed that, the distance from gonial point to mandibular foramen, mental foramen to mandibular border, mandibular foramen to pterygoid vertical was increased in horizontal growth pattern ie, 2205 mm ± 182, 1512 mm ± 106, 5720 mm ± 123, whereas it was reduced in vertical growth pattern ie, 1490 mm ± 155, 884 mm ± 141, 4795 mm ± 225 respectively Depth of curvature of mandibular canal was increased in horizontal growth pattern, 2225 mm ± 489; while it was reduced in vertical growth pattern ie, 1632 mm ± 118 Conclusions The findings of this study showed that the position and curvature of the mandibular canal reflect the outer morphology and growth pattern of the mandible
4 citations
References
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TL;DR: A structural method is described by which it may be possible to predict, from a single cephalogram, the course of rotation, where this feature is marked, and is based on information gained from implant studies of the remodeling process of the mandible during growth.
Abstract: A survey is presented of experience with the implant method in the study of facial growth, with particular emphasis on prediction of mandibular growth rotation. Three methods of prediction are discussed. (1) A longitudinal method, which consists of following the course of development by annual x-ray cephalograms, is shown to be of limited use for this purpose, as the remodeling process at the lower border of the mandible to a large extent masks the actual rotation. (2) A metric method, which aims at prediction based on a metric description of the facial morphology at a single stage of development, has so far not proved of value. (3) A structural method is described by which it may be possible to predict, from a single cephalogram, the course of rotation, where this feature is marked. This method is based on information gained from implant studies of the remodeling process of the mandible during growth.
809 citations
"Morphology of the mandibular canal ..." refers background or methods in this paper
...As the mandibular canal has a curved course post-natally ( Björk, 1969 ), it is presumed that the mandibular growth pattern is refl ected in its curvature....
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...The condylar growth pattern is individual and varies in direction and magnitude ( Björk, 1969 )....
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...By superimposing two radiographs taken at different ages and orientating them according to the contour of the mandibular canal, Björk (1969) demonstrated how the growth pattern of the mandible could be determined with a fairly high degree of accuracy....
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...In cephalometric studies with fi xed bone markers, Björk (1969) explained the complex rotation processes in normal and abnormal mandibular development and revealed that the mandibular canal is a stable structure during growth....
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...The internal morphology of the mandible, i.e. the mandibular canal, is stable on a profi le radiograph, whereas the external morphology is not ( Björk, 1969 )....
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TL;DR: The findings do not support the view that the matrix is a dominating factor and that bone formation is secondary in mandibular growth, but point to considerable independence in development of the two tissue systems.
Abstract: This paper examines the complex rotation processes that occur during growth in normal and abnormal mandibular development The bony mandibular corpus and its soft tissue covering, the matrix, are considered as independent tissue systems capable of independent rotation Both forward and backward rotation can be divided into three components: the total rotation, the matrix rotation, and the intramatrix rotation, showing different individual interrelationships and a changing composition in each individual during the entire period of development Dividing the mandibular rotation into these components permits measurement of the, often considerable, remodelling at the lower border of the mandible
Orthodontic treatment influences the components of mandibular rotation and thus induces a change in the remodelling of the mandible
The findings do not support the view that the matrix is a dominating factor and that bone formation is secondary in mandibular growth, but point to considerable independence in development of the two tissue systems
773 citations
"Morphology of the mandibular canal ..." refers background in this paper
...Rotation of the mandibular corpus during growth associated with substantial surface remodelling is well documented ( Björk and Skieller, 1983 )....
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...For permissions, please email: journals.permissions@oxfordjournals.org. doi:10.1093/ejo/cjn076 Advance Access publication 10 December 2008...
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...The finding of a relationship between the mandibular angle and the gonial angle supports the rotational pattern of the mandible identified by Björk and Skieller (1983 )....
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TL;DR: This study suggests that the contour of the anterior surface of the zygomatic process could be used as a reference structure in growth analysis as this contour kept a constant relation to implants in the infrazygomatic crest and closely followed the natural growth rotation of the maxilla.
Abstract: By use of the implant method the growth of the maxilla was analysed from profile and frontal (postero-anterior) cephalometric radiographs in nine boys with normal primary occlusion who were followe...
396 citations
"Morphology of the mandibular canal ..." refers background or methods in this paper
...The same bone marker method was also used to demonstrate the growth pattern of the maxillary complex ( Björk and Skieller, 1977 )....
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...For permissions, please email: journals.permissions@oxfordjournals.org. doi:10.1093/ejo/cjn076 Advance Access publication 10 December 2008...
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TL;DR: The prenatal formation of the human mandibular canal was described and it was suggested that rapid prenatal growth and remodeling in the ramus region result in a gradual coalescence of the canal entrances that is obvious at birth.
Abstract: The purpose of this study was to describe the prenatal formation of the human mandibular canal. Since bony canals develop in prenatal life around the nerve paths, it was assumed that the canal pattern could reflect the pattern of innervation of the dentition. Mapping of this early canal pattern does not appear to have been undertaken before. The material consisted of anthropological mandibles from the National Institute of Anthropology and History, Mexico City. A total of 302 human hemimandibles from the latter half of the prenatal period was investigated. The length, measured from the mental symphysis to the mandibular condyle, ranged from 28 to 60 mm. The dento-alveolar maturity was classified in two stages according to the appearance of alveolar sockets of deciduous and first permanent molars. The mandibles were radiographed with guttapercha points inserted into the canal openings (foramina) on the lingual surfaces of the mandibular rami. The study showed that the canal to the incisors appeared first, followed by the canal to the primary molars, and last by the one or more canals to the first permanent molars. In the most mature group, three different canals always occurred in each hemimandible. The canals were directed from the lingual surface of the mandibular ramus toward the different tooth groups. The inferior alveolar nerve presumably occurs in the mandible as three individual nerve paths originating at different stages of development. It is suggested that rapid prenatal growth and remodeling in the ramus region result in a gradual coalescence of the canal entrances that is obvious at birth. It is hypothesized that the pattern of tooth agenesis within the three groups of teeth is related to the three separate paths of innervation of the dentition.
159 citations
"Morphology of the mandibular canal ..." refers background in this paper
...It is known that in pre-natal life, the mandibular canal has a horizontal orientation ( Chavez-Lomeli et al. , 1996 ) and that the mental canal has not developed ( Kjær, 1989 )....
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...For permissions, please email: journals.permissions@oxfordjournals.org. doi:10.1093/ejo/cjn076 Advance Access publication 10 December 2008...
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...The reason for this was that this part of the mandibular canal is developed post-natally ( Chavez-Lomeli et al. , 1996 )....
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