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International Journal of Morphology

versión On-line ISSN 0717-9502

Int. J. Morphol. v.25 n.2 Temuco jun. 2007

http://dx.doi.org/10.4067/S0717-95022007000200019 

 

Int J. MorphoL, 25(2):353-356,2007.

 

A Pilot Study of the Mandibular Angle and Ramus in Indian Population

Estudio Piloto del Ángulo y Rama de la Mandíbula en la Población Hindú

 

*Rajalakshmi Rai; *Anu Vinod Ranade; *Latha Venkatraya Prabhu; *Mángala M. Pai; *Sampath Madhyastha & **Mángala Kumaran

*Department of Anatomy, Kasturba Medical College, Mangalore, Karnataka, 575004
** Department of Anatomy, Yenepoya, Medical College, Mangalore, Karnataka, India.

Dirección para correspondencia


SUMMARY: To evaluate the mandibular angle and to analyze the relationship of the angle and height & breadth of the ramus of the mandible to the gender, so as to study its role in the anthropological diagnosis. The angle, height and breadth of the ramus of adult dry human mandibles of both sexes were measured using a goniometer. The values obtained were analyzed statistically.

The present study showed a statistically significant difference in the mandibular angle as well as height of the ramus between both the sexes. The mean mandibular angle of Indian population when compared to that of European population was found to be lower by 9 degrees. The findings of this study might be useful in providing anthropological data that can also be used in dental and medical practice. However, the Indian mandible can be used for sexual dimorphism as is usual in anthropological work; it appears to possess important unfavourable anatomic factors that may predispose the individuals to difficult laryngoscopy or intubation.

KEYWORDS: Mandíbula; Mandibular angle; Ramus of the Mandible; Indian population.

RESUMEN: Para estudiar su rol en el diagnóstico antropológico, evaluamos el ángulo de la mandíbula y analizamos las relaciones de este ángulo con la altura y ancho de la rama de la mandíbula, en ambos sexos. Con un goniómetro, en huesos secos, fue obtenido el ángulo, alto y ancho de las mandíbulas humanas. Los valores obtenidos fueron analizados estadísticamente.

El estudio mostró diferencias estadísticamente significativas en el ángulo mandibular como también en la altura de la rama de la mandíbula, en ambos sexos. La media del ángulo mandibular de la población hindú fue 9 grados menor, comparada con la población europea. Los resultados de este estudio pueden ser útiles al aportar datos antropológicos utilizados en las prácticas médica y dental. Por otra parte, la mandíbula de los hindúes puede ser usada como dimorfismo sexual como es usual en trabajos antropológicos. Parece haber factores anatómicos desfavorabes importantes que pueden predisponer a los individuos a laringoscopías difíciles o intubación.

PALABRAS CLAVE: Mandíbula; Ángulo de la mandíbula; Rama de la mandíbula; Población Hindú.


INTRODUCTION

In the course of life the mandible undergoes substantial morphological and dimensional changes. The changes concerning mandibular angle, relation between the length of the mandibular corpus and ramus as well as roughness in the place of insertion of masseteric and pterygoid muscles do not depend upon age or sex but exclusively upon the dentition (Vinter et al, 1997). It is clear today that the statistical study of anthropometric data with the object of investigating racial origin and relationships requires number of subjects, or specimens, far in excess of those considered sufficient by earlier anthropologists (Cleaver, 1937). The angle of mandible varies with age and state of dentition (Zivanovich, 1970). These changes have been associated with the action of muscles of mastication (Avis, 1961). The mandibular angle, in conjunction with other anthropological parameters may be useful as anthropological tools in racial and / or population diagnosis. The present study was undertaken to evaluate and compare the angle, height, and width of the ramus of mandibles derived from cadavers of Indian origin. The findings of this study might be useful in providing anthropological data that can also be used in dental and medical practice.

MATERIAL AND METHOD

The measurements were taken from 88 male and 29 female human dry mandibles. The mandibles were moderately robust and were from dentious subjects. All mandibles were obtained from the skeleton collections of the department of anatomy of KMC Mangalore. The measurements were taken using gonioometer. The angles, height, and width of ramus of mandible were measured on both right and left sides and the mean of both the sides were taken for each parameter.

Statistical analysis: The significance of the difference between the angles of both male and female mandibles was tested using Mann- Whitney test. Also, the significance of the difference between the height of male and female mandibular ramus as well as between the width of male and female mandibular ramus were tested using Students t- test. The values are presented as mean ± Standard deviation. Statistical significance was considered as p<0.05.

RESULTS

The results depicted in Table 1a and 1b shows that there was a significant difference in the median angle between the male and female mandible (p< 0.083). As shown in Table II the height of the ramus of the male mandibles also showed a significant difference than that of the female mandible (p< 0.059). However, there was no significant difference in the breadth of the ramus between the two sexes. Table III shows the mean mandibular angles from different racial population groups. The widest mandibular angle was that of the Europeans (128°) and the narrowest was that of the Neanderthals (110°). The result of the present study shows that the mean mandiular angle of Indian population is 119°. The mean mandibular angle was greater in females (121°) than in males (118°) while the mean mandibular ramus height was greater in males (5.39cm) than in females (5.18cm).


 



DISCUSSION

Racial and regional differences in functional activity of the mandible during the early stages of development may affect its form and hence the mandibular angle (Gabriel, 1958). The angle of mandible varies with age and the state of dentition (Zivanovich). It ranges from about 170° in children to about 110°- 120° in adolescents and adulthood and then increases to about 130° to 140° in old age (Zivanovich). Several authors have shown that the state of dentition (such as tooth eruption, loss of teeth and absorption of the alveolar bone) is an important factor in determining the size of the human mandibular angle (Zivanovich; Keen, 1945). Some studies have also shown that the mandibular angle varies in different human population group (Mbajiorgu, 1996). Table II shows that the mandibular angle of Indian mandible (119°) was lesser than that of European population (128°), similar to the mean angle of Chinese population (119°) and greater than that of Neanderthals( 110°).

The non-significant difference between the mandibular angles of Chinese/Peruvians, Xanthoderms and African Negroes demonstrates some degree of homogeneity between these population groups (Table III). Since the difference between the Indian mandibular angles when compared to that of European mandible is relatively high, it may be considered for racial diagnosis. However, available literature suggests a 3° / 5° difference between the angles of the male and female mandibles (Zivanovic; Ricketts, 1975). According to Mbajiorgu et al. the mean mandibular angle and height were greater in females (128° and 6.13cm) than in males (123.06° and 5.98cm). The present study shows that the mandibular angle is greater in females (121°) than that of males (118°), whereas the height of the male mandibular ramus (5.39cm) is greater than that of female mandible (5.18cm). Our findings suggest that Indians have a short ramus and a narrow mandibular angle. According to Chou & Wu (1993) a relatively short mandibular ramus may be important, unfavorable anatomic factor in difficult laryngoscopy. Several workers have demonstrated that epigenetic factors, in particular, forces arising from the insertion of muscles are involved in the formation of an angular process (Avis; Herring, 1985). All muscles of mastication are attached to different parts of the ramus of the mandible. Experimental data make it clear that removal or denervation of the temporalis muscle produced marked reduction of the coronoid process of the mandible (Avis; Riesenfeld, 1969). On the contrary, masseteric hypertrophy leads to an enlargement of the angular process (Guggenheim & Cohem, 1959). The mandibular angle in conjunction with other anthropological parameters may be useful as anthropological tools in racial and / or population diagnosis. The findings of this study might be useful in providing anthropological data that can also be used in dental and medical practice. Although the Indian mandible can be used for sexual dimorphism as is usual in anthropological work, it appears to possess important unfavourable anatomic factors that may predispose the individuals to difficult laryngoscopy or intubation.

ACKNOWLEDGEMENTS: The authors are thankful to the statistian, Mrs. Asha Kamath, Department of Community Medicine, KMC, Manipal for her help in statistical analysis of the measurements taken.

 

REFERENCES

Avis, V. The significance of the angle of the mandible: An experimental and comparative study. Am. J. Phys. Anthropol, 55-61, 1961.        [ Links ]

Chou, H. C. & Wu, T. L. Mandibulo-hyoid distance in difficult laryngoscopy. Br. J. Anaesth., 71(3):335-9,1993.        [ Links ]

Cleaver, F. H. A contribution to the biometric study of the human mandible. Biometrica, 29:80-112, 1937.        [ Links ]

Gabriel, A. C. Some anatomical features of the mandible. J. Anal, 52:582-6, 1958.        [ Links ]

Guggenheim, P. & Cohem, L. External hyperostosis of the mandible angle associated with masseteric hypertrophy. Arch, Otol, 70:674-80, 1959.        [ Links ]

Herring, S. W The ontogeny of mammalian mastication. Am. Zool, 25:339-49, 1985.        [ Links ]

Keen, A. J. A study of the angle of the mandible. J. Dental Research, 24:99-108, 1945.        [ Links ]

Mbajiorgu, E.F.; Zivanovich, S.; Ásala, S.A. & Ma vera, G.A. A pilot study of mandibular angle in black Zimbabweans. Cent. Afr. J. Med., 42(10): 285-7, 1996.        [ Links ]

Ricketts, R. M. Mechanisms of mandibular growth: A series of enquires on the growth of the mandible, determinants of mandibular form and growth. In: Me Ñamara Jr. Ann Arbor: Centre for human growth and development, The University of Michigan, 1975. pp. 77-100.        [ Links ]

Riesenfeld, A. The adaptive mandible: An experimental study. Acta Anal, 72:246-62, 1969.        [ Links ]

Vinter, I. Krmpotic-Nemanic, J.; Ivankovic, D. & Jalsovec, D. The influence of the dentition of the shape of the mandible. CollegiumA nthropologicum, 20:555-60,1997.        [ Links ]

Zivanovich, S. The mandibular angle in the recent East African Bantu population. Arch. Oral. Biol, 15:1313-6, 1970.        [ Links ]

 

Received: 09-02-2007 Accepted: 20-04-2007

Correspondence to:

Rajalakshmi Rai
Department of Anatomy, CBS, KMC, Bejai,
Mangalore, Karnataka. 575004
INDIA
E-mail: rajalakshmirai@yahoo.co.in

 

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