|Year : 2015 | Volume
| Issue : 1 | Page : 7-10
Panoramic study of mandibular basal bone height
Raviraj Jayam1, Rajeshwari Annigeri2, Balaji Rao3, Satish Gadiputi4, Divya Gadiputi5
1 Department of Oral Medicine and Radiology, CKS Theja Dental College and Hospital, Tirupathi, Andhra Pradesh, India
2 Department of Oral Medicine and Radiology, College of Dental Sciences, Davanagere, Karnataka, India
3 Department of Oral Medicine and Radiology, Bapuji Dental College and Hospital, Davanagere, Karnataka, India
4 Department of Endodontics, Darshan Dental College, Udaipur, Rajasthan, India
5 Government Dental College, Bellary, Karnataka, India
|Date of Web Publication||20-May-2015|
Dr. Raviraj Jayam
Flat No. 301, Brindavan Apartments, Above Karur Vysya Bank, Khadi Colony, K.T Road, Tirupathi - 517 501, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Aims and Objectives: To provide information regarding the changes of mandibular basal bone height using panoramic radiography, in relation to age, sex, and the state of dentulousness, which could be utilized in clinical practice, especially in implantology and pre-prosthetic surgery. Materials and Methods: A total of 200 subjects, who were categorized according to age, sex, and state of dentulousness, were subjected to vertical measurements of mandibular basal bone in panoramic radiographs. Two measurements were made, D 1 and D 2 . The distance measured between the lower border of mental foramen to the lower border of the mandible was termed as D 1 . The distance between the lowest point of mandibular canal to the lower border of the mandible was termed as D 2 . These measurements were compared between males/females and dentulous/edentulous, which were further subjected to statistical analysis with Student's t-test. Results: Males had higher D 1 and D 2 values compared to females and edentulous groups had higher D 1 and D 2 values compared to dentulous subjects. Conclusions: Men have higher values of mandibular basal bone height compared to females and also that there exists some potential for mandibular basal bone to increase in height as the age progresses.
Keywords: Alveolar bone, bone deposition, mandibular basal bone, panoramic radiography
|How to cite this article:|
Jayam R, Annigeri R, Rao B, Gadiputi S, Gadiputi D. Panoramic study of mandibular basal bone height. J Orofac Sci 2015;7:7-10
|How to cite this URL:|
Jayam R, Annigeri R, Rao B, Gadiputi S, Gadiputi D. Panoramic study of mandibular basal bone height. J Orofac Sci [serial online] 2015 [cited 2019 Dec 8];7:7-10. Available from: http://www.jofs.in/text.asp?2015/7/1/7/157358
| Introduction|| |
Mandibular body is divided into alveolar bone and basal bone. However, there is no distinct line separating basal bone from alveolar bone tissue. This is more of a physiologic than an anatomic difference.  Basal bone forms the dental skeletal structure, contains most of the muscle attachments, and begins to form in the fetus before the teeth develop. Classically, the mandibular basal bone is defined as that part of the mandible which is present inferior to the mandibular canal.  The mandibular canal and the mental foramen are the standard anatomic reference landmarks used to differentiate between the alveolar bone and the basal bone in the mandible. 
Information is available that the aging skeleton retains a potential for growth. There is considerable evidence that continuous bone deposition takes place from adulthood to older-age and such changes have been reported on the skull and face.  There exists some amount of bone deposition along the lower border of the mandible as the age progresses,  which contribute to increase in the height of mandibular basal bone. On the contrary, it is also proved that alveolar ridge resorption in edentulous mandibles, can extend into the base of the mandibe,  leading to decrease in the height of mandibular basal bone.  Panoramic radiography is the most commonly used tool in measuring the mandibular basal bone height. ,
The aims of this study were:
- To measure and compare the height of mandibular basal bone in dentate and edentulous subjects.
- To assess the amount of differences in height of mandibular basal bone between males and females.
| Materials and Methods|| |
The present study consisted 200 subjects as study sample whose panoramic radiographs were obtained. Subject's consent was taken and clearance from the ethical committee was obtained. [Table 1] shows the distribution of subjects with the criteria of age, sex, and state of dentulousness.
Panoramic machine (Siemens, Orthophos 3/3C, Sirona Dental Systems GMbH, Bensheim, Germany) and panoramic films 6" × 12" (T-Mat) were used to record the images. Interpretation of radiographs was carried out in a dark room with the help of radiographic viewer and a magnifying lens. The radiographs were interpreted for location of the anteroposterior course of the mandibular canal, visibility of mental foramen, and lower border of the mandible.
The methodology of recording the distances (D 1 and D 2 ) followed in this study was adopted from Xie et al., (1996)  [Figure 1]. A tangential line was drawn to the lower border of the mandible, on either side (right (R) and left (L)). Vertical lines were drawn from the lowest point of the mental foramen and the lowest point of the mandibular canal to the lower border of the mandible using a Hi-Tech point pen and the distances of the same were measured on both the left and right sides using vernier calipers (sensitive up to 0.05 mm). The distances were measured perpendicular to the tangential line drawn to the lower border of the mandible. The distance measured between the lower border of mental foramen to the lower border of the mandible was termed as D 1 . The distance between the lowest point of mandibular canal to the lower border of the mandible was termed as D 2 . Similar measurements were carried out for all the radiographs.
|Figure 1: D 1 = Distance between the lower border of the mental foramen and the lower border of the mandible, D 2 = distance between the lowermost point of the inferior alveolar canal and the lower border of the mandible, 1 = mental foramen, 2 = lower border of the inferior alveolar canal, 3 = tangential line drawn to the lower border of the mandible|
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The measured values were compared and statistically analyzed. The mean values of different groups (age, sex, and state of dentulousness) were compared using the Student's t-test.
x 1 = mean value of one group
x 2 = mean value of second group
SD = standard deviation
n = number of individuals
Once the t-value was calculated, P (probability)-value was obtained using the standard chart for statistical significance.
| Results|| |
In the present study, the right- and left-sided measurements were combined, as there were no statistical differences between them. Hence, a total of 800 values were achieved (400 D 1 and 400 D 2). Among 800 values (i.e., 400 D 1 and 400 D 2 measurements), 11 (2.75%) D 1 and 29 (7.25%) D 2 measurements could not be measured due to inability to interpret the radiographs accurately for the technical and anatomical reasons. The results obtained are shown in [Table 2]. Further, the difference of D 1 and D 2 values between males and females, dentulous and edentulous were calculated, compared with other studies and subjected to statistical analysis [Table 3] and [Table 4].
|Table 2: Showing range of values of D 1 and D 2 in males and females of various groups. Parenthesis shows mean value with standard deviation|
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|Table 3: Showing difference of D 1 and D 2 values between males and females. Parenthesis shows statistical significance and values in other studies|
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|Table 4: Showing difference of values in dentulous and edentulous subjects of males and females|
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| Discussion|| |
On comparing the results, males had higher D 1 and D 2 values except for Group II (31-40 years), where females had higher D 1 values compared to males. Though, in all the values, males were higher compared to females, none of them were statistically significant, except for D 2 values in Group III, which were statistically significant (P-value <0.03). This was in accordance with Xie et al., (1996),  who had obtained similar results. This can be explained on the basis of fact that sexual hormones such as androgens and estrogen, contribute to the development of a morphologic difference in craniofacial skeletons between the genders and even to different velocity of growth in later adulthood. The speed of bone growth in adult women is lower than in mean, as observed by Enlow (1982),  who further stated that local factors such as masticatory muscles and bite force play an important role in craniofacial skeletal change. Tension is known to induce bone formation. Since the mandible functions as lever, contraction of jaw elevator muscles such as masseter and medial pterygoid muscle during normal chewing movements may cause a small amount of tension along lower border of mandible in the molar regions. In general, men have stronger muscles and greater bite force than women, so more amount of bone deposition along the lower border of the mandible was observed in men compared to women. The sexual hormones and various strengths of force of masticatory muscles together explained the difference in height of mandibular basal bone between the genders. Further, women in postmenopausal age had accelerated rate of resorption of residual edentulous ridge due to osteoporosis, which was supported by von Wowern et al., (1980). 
In the present study, D 1 and D 2 values in the edentulous group were higher compared to dentulous group. This suggested that height of mandibular basal bone increased as the age progressed, which was also supported by Soikkonen et al., and Xie et al. Increase in height of mandibular basal bone, as age progressed, can be explained on the basis that bone deposition takes place along the lower border of the mandible in the adulthood. This was supported by Newman and Levers, (1979);  Levers and Darling, (1983);  Whittaker et al., (1990);  and Xie et al., (1996).  Further, Enlow (1982)  stated that tension created along lower border of the mandible due to action of masseter and medial pterygoid muscles can induce bone formation along lower border of mandible.
In conclusion, males had higher D 1 and D 2 values compared to females, though all were not statistically significant. Edentulous subjects had higher D 1 and D 2 values compared to dentulous groups, which were statistically significant. The fact that the height of mandibular basal bone increases as the age progressed; can be practically applied in the fields of implantology and pre-prosthetic surgery, which are gaining more popularity in the today's practice. However, due to inherent disadvantages/limitations of panoramic radiography namely distortion and magnification, advanced imaging modalities like digital radiography, CT, etc., are suggested for future studies, with a larger sample size.
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[Table 1], [Table 2], [Table 3], [Table 4]