Zahraa.docx J Bagh College Dentistry Vol. 27(2), June 2015 Hard palate bone Pedodontics, Orthodontics and Preventive Dentistry163 Hard palate bone density and thickness determination using CT scan and their relationships with body compositions measured by bioelectrical impedance analysis for Iraqi adult sample Zahraa M. Al- Fadily, B.D.S. (1) Hadeel A. Al- Hashimi, B.D.S., M.Sc. (2) ABSTRACT Background: This study was conducted to evaluate the hard palate bone density and thickness during 3rd and 4th decades and their relationships with body mass index (BMI) and compositions, to allow more accurate mini-implant placement. Materials and method: Computed tomographic (CT) images were obtained for 60 patients (30 males and 30 females) with age range 20-39 years. The hard palate bone density and thickness were measured at 20 sites at the intersection of five anterioposterior and four mediolateral reference lines with 6 and 3 mm intervals from incisive foramen and mid-palatal suture respectively. Diagnostic scale operates according to the bioelectric impedance analysis principle was used to measure body weight; percentages of body fat, water, and muscle; bone mass; and basal and active metabolic rates. Results: No significant difference in overall bone density and thickness of hard palate during 3rd and 4th decades. The gender should be considered in regard to bone thickness. Cortical bone density and thickness showed a tendency to decrease posteriorly, while the cancellous bone density showed a tendency to increase posteriorly. In the mediolateral areas, no specific patterns were observed. With increasing BMI, the cortical bone density was increased. The relationships of bone density and thickness with most scale measurements were not significant. Conclusion: Mini-implants for orthodontic anchorage can be effectively placed in most areas of hard palate regarding the bone density. While regarding bone thickness, care should be taken during the planning of their placement in hard palate. A new classification for bone thickness of hard palate has been developed. Keywords: Bone density, bone thickness, computerized tomography, hard palate, orthodontic mini implant. (J Bagh Coll Dentistry 2015; 27(2):163-172). INTRODUCTION Anchorage is of fundamental importance in orthodontic treatment (1). Orthodontic mini- implants have expanded the scope of traditional orthodontic treatment because they provide an excellent alternative to traditional compliance- dependent, tooth-borne anchorage methods (2). The non-tooth bearing area of the hard palate has been used as a host site for orthodontic implant anchorage because of sufficient bone quality and less possibility of root damage or interference with tooth movement during treatment in addition to the easy access of placing mini-screws in this area (3). Furthermore, thick and keratinized palatal mucosa is related to less inflammation (4) and guarantees biomechanical stability for placement of miniscrews (5). Bioelectrical Impedance analysis (BIA) is used to estimate body composition using the difference of conductivity based on the biological characteristic of tissue. Conductivity is proportional to water and electrolyte and it is decreased when cell shape is closer to a round form. (1) Master Student, Department of Orthodontics, College of Dentistry, University of Baghdad. (2) Assist. Professor, Department of Orthodontics, College of Dentistry, University of Baghdad. Adipose tissue is composed of round shape cell and contains relatively less water than other tissues like muscle, so conductivity is decreased according to the increase of body fat (6). As the bone density and thickness are two critical factors for success of mini-implant, this study aimed to obtain data that will serve as a guiding map to select the most suitable sites for placement of mini-implants in the hard palate regarding bone density (cortical and cancellous) and thickness during 3rd and 4th decades, and to assess if there is any relationships with BMI and different body compositions. MATERIALS AND METHODS Sixty Iraqi patients were selected from the patients attending MRI and CT department of AL- Sader Medical City in AL-Najaf and divided equally into: group I (20-29 years); and group II (30-39 years). Inclusion criteria included: 1. Skeletal Class Ι with normal occlusion. 2. Full set of dentition in the upper and lower left and/or right side (excluding third molar). 3. No erupted supernumerary and/or any impacted teeth within the area of measurement. J Bagh College Dentistry J Bagh College Dentistry Pedodontics, Orthodontics and Preventive Dentistry 4. No history of a systemic disease and no previous could affect bone health. 5. No syndromes of cleft palate, and no pathological lesion in the palate 6. No history of orthodontic treatment and/or orthognathic surgery. 7. No regular tobacco smoking and/or alcohol consumption. This study was approved by the Scientific Committee of College of Dentistry University of Baghdad. For each patient, informed consent was obtained before the start of examination. Body Weight and diagnostic scale measurements (Body Fat, Water, Muscle Percentages; Bone Mass; and Basal (BMR) and Active (AMR) Metabolic Rates were recorded while the subject wearing light clothes (during summer season), bare feet and was in a stable standing on a diagnostic scale (Beurer, Germany) which operates according to BI BMI was calculated. CT images were obtained by 64 detector CT scanner (Philips, Holland, Brilliancetm CT, V palate bone density in Hounsfield unit (HU) and thickness in millimeter (mm). The refer were determined to be from 0 to 24 mm at 6 mm intervals posterior to the level of the posterior margin of the incisive foramen and from 0 to 9 mm at 3 mm intervals lateral to the mid suture with the aid of equally sized grid of 3 mm intervals (Figure 1). The measurements were made at the intersection points of the reference lines over 20 sites covering 216 mm right side de that refer there were no statistical significant differences measurements. At each determined point (sagittal view); the midpoint of the cortical bone thickness was selected to represent the cortical bone density, the density of the cancellous bone was measured at the trabeculae, loc between the two cortical plates, and the hard palate bone thickness (sum of cortical bone facing the oral cavity, cancellous bone and cortical bone facing the nasal cavity) was measured perpendicular to the horizontal plane. Som these me The measured values were averaged for each sample, keeping specific to the designated area. According to the reference lines, there were 3 designated anteroposterior areas: anterior (0,6 mm); middle ( mm). Likewise, 4 designated mediolateral areas: J Bagh College Dentistry Pedodontics, Orthodontics and Preventive Dentistry No history of a systemic disease and no previous chronic use of any medication that could affect bone health. No syndromes of cleft palate, and no pathological lesion in the palate No history of orthodontic treatment and/or orthognathic surgery. No regular tobacco smoking and/or alcohol consumption. This study was approved by the Scientific Committee of College of Dentistry University of Baghdad. For each patient, informed consent was obtained before the start of examination. Body Weight and diagnostic scale measurements (Body Fat, Water, Muscle entages; Bone Mass; and Basal (BMR) and Active (AMR) Metabolic Rates were recorded while the subject wearing light clothes (during summer season), bare feet and was in a stable standing on a diagnostic scale (Beurer, Germany) which operates according to BI BMI was calculated. CT images were obtained by 64 detector CT scanner (Philips, Holland, Brilliancetm CT, V 4.0) and used to measure hard palate bone density in Hounsfield unit (HU) and thickness in millimeter (mm). The refer were determined to be from 0 to 24 mm at 6 mm intervals posterior to the level of the posterior margin of the incisive foramen and from 0 to 9 mm at 3 mm intervals lateral to the mid suture with the aid of equally sized grid of 3 mm rvals (Figure 1). The measurements were made at the intersection points of the reference lines over 20 sites covering 216 mm right side depending on the previous studies that refer there were no statistical significant differences between the left and right side measurements. At each determined point (sagittal view); the midpoint of the cortical bone thickness was selected to represent the cortical bone density, the density of the cancellous bone was measured at the trabeculae, located halfway incisoapically between the two cortical plates, and the hard palate bone thickness (sum of cortical bone facing the oral cavity, cancellous bone and cortical bone facing the nasal cavity) was measured perpendicular to the horizontal plane. Som these measurements were illustrated in F The measured values were averaged for each sample, keeping specific to the designated area. According to the reference lines, there were 3 designated anteroposterior areas: anterior (0,6 mm); middle (12 mm); and the posterior (18,24 mm). Likewise, 4 designated mediolateral areas: J Bagh College Dentistry Pedodontics, Orthodontics and Preventive Dentistry No history of a systemic disease and no chronic use of any medication that could affect bone health. No syndromes of cleft palate, and no pathological lesion in the palate No history of orthodontic treatment and/or orthognathic surgery. No regular tobacco smoking and/or alcohol This study was approved by the Scientific Committee of College of Dentistry University of Baghdad. For each patient, informed consent was obtained before the start of examination. Body Weight and diagnostic scale measurements (Body Fat, Water, Muscle entages; Bone Mass; and Basal (BMR) and Active (AMR) Metabolic Rates were recorded while the subject wearing light clothes (during summer season), bare feet and was in a stable standing on a diagnostic scale (Beurer, Germany) which operates according to BIA principle. Then CT images were obtained by 64 detector CT scanner (Philips, Holland, 4.0) and used to measure hard palate bone density in Hounsfield unit (HU) and thickness in millimeter (mm). The refer were determined to be from 0 to 24 mm at 6 mm intervals posterior to the level of the posterior margin of the incisive foramen and from 0 to 9 mm at 3 mm intervals lateral to the mid suture with the aid of equally sized grid of 3 mm rvals (Figure 1). The measurements were made at the intersection points of the reference lines over 20 sites covering 216 mm pending on the previous studies that refer there were no statistical significant between the left and right side At each determined point (sagittal view); the midpoint of the cortical bone thickness was selected to represent the cortical bone density, the density of the cancellous bone was measured at ated halfway incisoapically between the two cortical plates, and the hard palate bone thickness (sum of cortical bone facing the oral cavity, cancellous bone and cortical bone facing the nasal cavity) was measured perpendicular to the horizontal plane. Som asurements were illustrated in F The measured values were averaged for each sample, keeping specific to the designated area. According to the reference lines, there were 3 designated anteroposterior areas: anterior (0,6 12 mm); and the posterior (18,24 mm). Likewise, 4 designated mediolateral areas: J Bagh College Dentistry Vol. 2 Pedodontics, Orthodontics and Preventive Dentistry No history of a systemic disease and no chronic use of any medication that No syndromes of cleft palate, and no pathological lesion in the palate. No history of orthodontic treatment and/or No regular tobacco smoking and/or alcohol This study was approved by the Scientific Committee of College of Dentistry University of Baghdad. For each patient, informed consent was obtained before the start of examination. Body Weight and diagnostic scale measurements (Body Fat, Water, Muscle entages; Bone Mass; and Basal (BMR) and Active (AMR) Metabolic Rates were recorded while the subject wearing light clothes (during summer season), bare feet and was in a stable standing on a diagnostic scale (Beurer, Germany) A principle. Then CT images were obtained by 64-slice multi detector CT scanner (Philips, Holland, 4.0) and used to measure hard palate bone density in Hounsfield unit (HU) and thickness in millimeter (mm). The reference lines were determined to be from 0 to 24 mm at 6 mm intervals posterior to the level of the posterior margin of the incisive foramen and from 0 to 9 mm at 3 mm intervals lateral to the mid-palatal suture with the aid of equally sized grid of 3 mm rvals (Figure 1). The measurements were made at the intersection points of the reference lines over 20 sites covering 216 mm2 in the left or pending on the previous studies (4,7 that refer there were no statistical significant between the left and right side At each determined point (sagittal view); the midpoint of the cortical bone thickness was selected to represent the cortical bone density, the density of the cancellous bone was measured at ated halfway incisoapically between the two cortical plates, and the hard palate bone thickness (sum of cortical bone facing the oral cavity, cancellous bone and cortical bone facing the nasal cavity) was measured perpendicular to the horizontal plane. Some of asurements were illustrated in Figure (2). The measured values were averaged for each sample, keeping specific to the designated area. According to the reference lines, there were 3 designated anteroposterior areas: anterior (0,6 12 mm); and the posterior (18,24 mm). Likewise, 4 designated mediolateral areas: Vol. 27(2), June 2015 Pedodontics, Orthodontics and Preventive Dentistry164 No history of a systemic disease and no chronic use of any medication that No syndromes of cleft palate, and no No history of orthodontic treatment and/or No regular tobacco smoking and/or alcohol This study was approved by the Scientific Committee of College of Dentistry University of Baghdad. For each patient, informed consent was Body Weight and diagnostic scale measurements (Body Fat, Water, Muscle entages; Bone Mass; and Basal (BMR) and Active (AMR) Metabolic Rates were recorded while the subject wearing light clothes (during summer season), bare feet and was in a stable standing on a diagnostic scale (Beurer, Germany) A principle. Then slice multi- detector CT scanner (Philips, Holland, 4.0) and used to measure hard palate bone density in Hounsfield unit (HU) and ence lines were determined to be from 0 to 24 mm at 6 mm intervals posterior to the level of the posterior margin of the incisive foramen and from 0 to 9 palatal suture with the aid of equally sized grid of 3 mm rvals (Figure 1). The measurements were made at the intersection points of the reference in the left or (4,7-9), that refer there were no statistical significant between the left and right side At each determined point (sagittal view); the midpoint of the cortical bone thickness was selected to represent the cortical bone density, the density of the cancellous bone was measured at ated halfway incisoapically between the two cortical plates, and the hard palate bone thickness (sum of cortical bone facing the oral cavity, cancellous bone and cortical bone facing the nasal cavity) was measured e of igure (2). The measured values were averaged for each sample, keeping specific to the designated area. According to the reference lines, there were 3 designated anteroposterior areas: anterior (0,6 12 mm); and the posterior (18,24 mm). Likewise, 4 designated mediolateral areas: mid (6 mm); lateral (9 mm) (Figure 1). Figure 2: thickness at different points (sagittal view). the most common tooth or the area between two teeth that appeared in each reference line was recorded. It was observed: Anteroposteriorly (AP); Line 0 Line 6 Line 12 Line 18 Line 24 Mediolate Line 0 Line 3 Line 6 Line 9 June 2015 164 mid-palatal area (0 mm); medial (3 mm); middle (6 mm); lateral (9 mm) (Figure 1). Figure 1: Grid, reference lines, points of measurements in CT (axial view). Figure 2: Measurement of bone density and thickness at different points (sagittal view). In order to make the evaluation more clinical, the most common tooth or the area between two teeth that appeared in each reference line was recorded. It was observed: Anteroposteriorly (AP); Line 0 - distal third of the canine. Line 6 - distal margin of the first premolar. Line 12 - distal margin of the second premolars. Line 18 - distal third of the first molar. Line 24 - mesial third of the second molars. Mediolateraly (ML); Line 0 - the area between two central incisors. Line 3 - distal third of the central incisor. Line 6 - mesial margin of the lateral incisor. Line 9 - distal margin of the lateral incisor. June 2015 palatal area (0 mm); medial (3 mm); middle (6 mm); lateral (9 mm) (Figure 1). Figure 1: Grid, reference lines, points of measurements in CT (axial view). Measurement of bone density and thickness at different points (sagittal view). In order to make the evaluation more clinical, the most common tooth or the area between two teeth that appeared in each reference line was recorded. It was observed: Anteroposteriorly (AP); distal third of the canine. distal margin of the first premolar. distal margin of the second premolars. distal third of the first molar. mesial third of the second molars. raly (ML); the area between two central incisors. distal third of the central incisor. mesial margin of the lateral incisor. distal margin of the lateral incisor. Hard palate bone palatal area (0 mm); medial (3 mm); middle (6 mm); lateral (9 mm) (Figure 1). Figure 1: Grid, reference lines, points of measurements in CT (axial view). Measurement of bone density and thickness at different points (sagittal view). In order to make the evaluation more clinical, the most common tooth or the area between two teeth that appeared in each reference line was distal third of the canine. distal margin of the first premolar. distal margin of the second premolars. distal third of the first molar. mesial third of the second molars. the area between two central incisors. distal third of the central incisor. mesial margin of the lateral incisor. distal margin of the lateral incisor. Hard palate bone palatal area (0 mm); medial (3 mm); middle Figure 1: Grid, reference lines, points of measurements in CT (axial view). Measurement of bone density and thickness at different points (sagittal view). In order to make the evaluation more clinical, the most common tooth or the area between two teeth that appeared in each reference line was distal margin of the first premolar. distal margin of the second premolars. mesial third of the second molars. the area between two central incisors. distal third of the central incisor. mesial margin of the lateral incisor. distal margin of the lateral incisor. Hard palate bone J Bagh College Dentistry Vol. 27(2), June 2015 Hard palate bone Pedodontics, Orthodontics and Preventive Dentistry165 RESULTS There were no statistically significant differences in the overall bone density and bone thickness between group Ι and ΙΙ (Table 1). According to this result, the matching measurements from both groups were combined. There was no statistically significant difference between the males and females in the bone density measurements; while a statistically significant difference between them in the bone thickness measurements (Table 2). Based on this result, the bone density measurements of males and females were combined. The males tended to show greater mean value than females with a statistically significant difference between them in the anterior area and in all mediolateral areas (Table 3). Comparisons of bone density and bone thickness for male and female among the three anteroposterior areas and the four mediolateral areas were performed by repeated measure analysis. There were a highly statistically significant difference (p<0.001) in bone density among these areas. Consequently, Cohen's d and Bonferonni adjusted paired tests were done for each paired comparisons of these areas as illustrated in tables 4 and 5. According to ANOVA trend, the relationship of BMI with cortical bone density was statistically significant, as with increasing the BMI, the cortical bone density increased, while with cancellous bone density and bone thickness for males and females was not (Table 6). The relationship of the cortical bone density with diagnostic scale measurements was not statistically significant. The results of the cancellous bone density were similar to those of the cortical bone density except with body water percentage which was statistically significant. While the relationship of the bone thickness with bone mass and with BMR and AMR was statistically significant (Table 7). In the present study, the bone density of the designated areas of the hard palate was distributed according to Misch’s(10) classification; while the bone thickness, according to the new classification that has been developed by this study (Table 8 and 9) which includes: ∗ T1 thick bone - bone thickness greater than 13 mm. ∗ T2 proper bone - bone thickness value greater than7 to13 mm. ∗ T3 risky bone was - bone thickness value between 4-7 mm. ∗ T4 improper bone - bone thickness less than 4 mm. DISCUSSION The age range of the sample was selected to be (20-39 years) because before this age, the peak bone mass still not achieved (11), and after this age subsequent age-related bone loss appears (12).This may explain the no age difference. This study found no significant gender differences in the bone density. Since males and females eat essentially the same types of food, the strains produced during mastication might be expected to be similar, as would bone density. Other studies showed that females had greater palatal cortical bone density than males did (7,13). On the other hand, the present study found significant gender differences of bone thickness in the anterior area and in all mediolateral areas. This can be explained as males acquire more bone mass than females (a bigger-not a denser- skeleton) (14), and may be attributed to the fact that the females have a reduced tongue strength compared to males (15). According to Wolff’s law that states "bone structure is altered depending on the loads that are placed on it" (16), and as the tongue plays an important role in speech, mastication and swallowing by its contact with the hard palate (17). Furthermore, the magnitude and duration of the tongue pressure were found to be significantly larger in the anteriomedian and smaller in the posteriomedian parts of hard palate compared to the other parts (18). Ryu et al. (9) and Gracco et al. (19) found no statistically significant differences due to gender in bone thickness of the hard palate. These differences with others may be explained by factors of race, hormones, and life style and also may belong to the difference in the measuring sites and/or the difference in the CT scanning machine setting. The result of present study showed that the cortical bone density and bone thickness had a tendency to decrease significantly anteroposteriorly, while the cancellous bone density had a tendency to increase. The mean of cancellous bone density in the posterior area was higher than that in the middle area but statistically not significant.Menegaz et al.(20)foundthe data that support a role of mechanical loading in the determination of palatal morphology and that elevated masticatory loading developed hard palate with significantly greater bone area, and thicker anterior palates. Role, magnitude and duration of tongue pressure were significant in the anteromedian part of hard palate (17,18). Furthermore and just as could be expected from the triangular sagittal cross section of the palate, the result of present study regarding cortical bone density and thickness can be explained as the anterior area is nearest to masticatory function of J Bagh College Dentistry Vol. 27(2), June 2015 Hard palate bone Pedodontics, Orthodontics and Preventive Dentistry166 the teeth and tongue pressure than middle and posterior areas. About the cancellous bone density, the anterior area had higher bone thickness than the middle and posterior areas, so the decrease in the thickness of bone is associated with more concentrated trabeculae. The result of present study is in agreement with Han et al. (7) and Moon et al. (13) regarding the cortical bone density, and in disagreement with Han et al. (7) regarding the cancellous bone density who found it decreasing posteriorly. Regarding the bone thickness, the result is in agreement with others (8,9,19,21-23). The bone density and thickness didn't take organized pattern mediolaterly, as mid-palatal area showed lowest cortical bone density and highest cancellous bone density and bone thickness. Medial area showed highest cortical bone density and lowest cancellous bone density, while middle area showed lowest bone thickness. Direct comparison with other studies is difficult since there was no previous study investigating the area of mid-palatal suture and there is difference in the way of designing mediolateral areas. Concerning mid-palatal suture, in the immediate postnatal period, the fine cancellous bone of the palate was replaced by bone having a cortex and medullary spaces, and the medial ends of the palatal processes gradually thickened. During the first 2 years, the inferior cortical layer remained cancellous in nature due to the rapid deposition of bone on its oral surface; the intermaxillary suture increased markedly in height and became narrower (24). This fact can explain that the bone in the mid-palatal suture has specific characteristics differ from that in the others mediolateral areas. Explanation of other results related to mediolateral areas may be attributed to the facts mentioned previously about the shape of hard palate bone in coronal section, effect of tongue pressure on the cortical bone density and bone thickness, and as cancellous bone in the lateral area lies adjacent to the roots of the maxillary teeth and is subjected to the stress of masticatory forces. The sample of present study included normal, overweight and obese categories of the international classification of BMI (25). It was found that obesity leads to upper airway narrowing due to enlargement of soft palate, lateral pharyngeal walls, para-pharyngeal fat pads, and tongue (26,27). Furthermore, the weight of a muscle reflects the forces that it exerts on bones to which it is attached and that muscle weight is an important determinant of bone mass (28). Accordingly, the result of this study may be explained as that increase in BMI is associated with an enlargement of tongue which implied more pressure on the cortical bone. There is no previous study examining this relationship. In this study, the hard palate bone density was not related to the body composition, except the cancellous bone density in relation to the body water percentage which may be belong to the fact that the water ratio is higher in trabecular than in cortical bones (29). The relationships of bone thickness with bone mass, BMR and AMR were statistically significant. There is no previous study examining these relationships. This result may be explained as if all individuals had the same size of hard palate whatever their skeleton size, some would have hard palate that was inadequate for the task and others would be at a disadvantage through having hard palate that was significantly heavier than it needed to be. Additionally, the BMR and AMR are influenced by weight and height (30). So it is expected that the heavier individuals (including their hard palate) will have fastest BMR and AMR. The bone density measurements of the present study were distributed according to Misch’s (10) classification who classified the bones into 5 categories according to density. Consequently, the mean of cortical bone density in the anteroposterior and mediolateral areas was D2 (850-1250HU), while the mean of cancellous bone density in the anteroposterior and mediolateral areas was D3 (350-850HU). There is no previous classification of bone thickness. In the palate, the big challenge is the length of mini- screws.23 So the present study classified the bone thickness into four categories depending on mini- screw length as there must be sufficient bone thickness to receive the functional part of the mini-screw, without perforating the nasal cavity plus a safety zone of 1 mm. T1 and T2 categoriesare classified as there will be sufficient bone thickness to receive the functional part of the mini-screw, ranging from 6 to 12 mm in length, without perforating the nasal cavity (4,8,19) and a safety margin of 1 mm is recommended (31). T3 category is classified asthe limited availability of palatal bone height which was the reason for the development of special short palatal implants for orthodontic anchorage (3 to 6 mm long) (32). T4 category is classified as the shortest endosseous part of short palatal implant is 3 mm long (31). Also it has been reported that a risky region for palatal implant placement is one with a height of less than 4 mm (4,33). So T4 is considered as improper bone for placement of mini-screw. The present study found that anteroposteriorly, the J Bagh College Dentistry Vol. 27(2), June 2015 Hard palate bone Pedodontics, Orthodontics and Preventive Dentistry167 mean of bone thickness for males and females in the anterior area was T2, in the middle area was T3, while in the posterior area was T3 for males and was T4 for females. Mediolaterally, the mean of bone thickness in the mid-palatal area was T2 for males and was T3 for females. In other mediolateral areas, the mean of bone thickness for both males and females was T3. It was concluded that bone thickness is more important than the bone density to be considered when planning to place mini-implant for orthodontic anchorage in the hard palate. A new classification for bone thickness of the hard palate has been developed and a preliminary guiding map to select the most suitable sites for placement of mini-implants in the hard palate was established. REFERENCES 1. Wu TY, Kuang SH, Wu CH. Factors associated with the stability of mini-implants for orthodontic anchorage: a study of 414 samples in Taiwan. J Oral Maxillofac Surg 2009; 67(8): 1595-9. 2. Favero L, Brollo P, Bressan E. Orthodontic Anchrage with Specific fixtures: Related Study Analysis. Am J Orthod Dentofacial Orthop 2002; 122: 84-94. 3. Jung BA, Kunkel M, Gollner P, Liechti T, Wehrbein H. Success rate of second-generation palatal implants. Angle Orthod 2009; 79: 85-90. 4. Kang S, Lee S, Ahn S, Heo M, Kim T. Bone Thickness of the Palate for Orthodontic Mini-implant Anchorage in Adults. Am J Orthod Dentofacial Orthop 2007; 131: S74-80. 5. Kyung SH, Hong SG, Park YC. Distalization of maxillary molars with a midpalatal miniscrew. J Clin Orthod 2003; 37: 22-6. 6. Gang J. Suitable Method to Body Fat Assessment and Follow-up Examination. The 10th Workshop of KOSSO in 2005; 261-9. 7. Han S, Bayome M, Lee J, Lee YJ, Song HH, Kook YA. Evaluation of palatal bone density in adults and adolescents for application of skeletal anchorage devices. Angle Orthod 2012; 82: 625-31. 8. Baumgaertel S. Quantitative investigation of palatal bone depth and cortical bone thickness for mini- implant placement in adults. Am J Orthod Dentofacial Orthop 2009; 136: 104-108. 9. RyuJH, Park JH, Thu TVT, Bayome M, Kim YJ, Ah Kook Y. Palatal bone thickness compared with cone- beam computed tomography in adolescents and adults for mini-implant placement. Am J Orthod Dentofacial Orthop 2012; 142: 207-12. 10. Misch CE. Density of bone: effect on treatment plans, surgical approach, healing, and progressive bone loading. Int J Oral Implantol 1990; 6(2): 23-31. 11. Gardner DG, Shoback D. Greensspan's basic and clinical endocrinology. 9th ed. McGraw-Hill, 2011. 12. Riggs BL, Melton ILJ, Robb RA, Camp JJ, Atkinson EJ, Peterson JM, Rouleau PA, McCollough CH, Bouxsein ML, Khosla S. A population-based study of age and sex differences in bone volumetric density, size, geometry and structure at different skeletal sites. J of Bone Mineral Research 2004; 19(12): 1945-54. 13. Moon CH, Park HK, Nam JS, Im JS, Baek SH. Relationship between vertical skeletal pattern and success rate of orthodontic mini-implants. Am J Orthod Dentofacial Orthop 2010; 138(1): 51-7. 14. Callewaert F, Venken K, Kopchick JJ, Torcasio A, Lenthe GHV, Boonen S, Vanderschueren D. Sexual Dimorphism in Cortical Bone Size and Strength But Not Density Is Determined by Independent and Time- Specific Actions of Sex Steroids and IGF-1: Evidence from Pubertal Mouse Models. American Society for Bone and Mineral Research 2010; 25(3): 617-26. 15. Youmans SR, Youmans GL, Stierwalt JAG. Differences in Tongue Strength Across Age and Gender: Is There a Diminished Strength Reserve? Dysphagia 2009; 24 (1): 57-65. 16. Wolff J. Das Gestetz der Transformation der Knocken .Hirshewold, Berlin 1892. 17. Hori K, Ono T, Nokubi T. Coordination of tongue pressure and jaw movement in mastication. J Dent Res 2006; 85(2): 187-91. 18. Ono T, Hori K, Nokubi T. Pattern of tongue pressure on hard palate during swallowing. Dysphagia 2004; 19(4): 259-264. 19. Gracco A, Lombardo L, Cozzani M, Siciliani G. Quantitative cone-beam computed tomography evaluation of palatal bone thickness for orthodontic miniscrew placement. Am J Orthod Dentofacial Orthop 2008; 134: 361-9. 20. Menegaz RA, Sublett SV, Figueroa SD, Hoffman TJ, Ravosa MJ. Phenotypic Plasticity and Function of the Hard Palate in Growing Rabbits. The Anatomical Record 2009; 292: 277-84. 21. Jayakumar G, Rajkumar, Biju T, George MA, Krishnaswamy NR. Quantitative assessment of palatal bone thickness in an ethnic Indian population: A computed tomography study. Indian J Dent Res 2012; 23(1): 49-52. 22. Farnsworth D, Rossouw PE, Ceen RF, Buschang PH. Cortical bone thickness at common miniscrew implant placement sites. Am J Orthod Dentofacial Orthop 2011; 139(4): 495-503. 23. Marquezan M, Nojima LI, Freitas AOA, Baratieri C, Júnior MA, Nojima MCG, Araújo MTS. Tomographic mapping of the hard palate and overlying mucosa. Brazilian Oral Research 2012; 26(1): 36-42. 24. Latham RA. The development, structure and growth pattern of the human mid-palatal suture. J Anat 1971; 108(1): 31-41. 25. WHO. Obesity: preventing and managing the global epidemic. Report of a WHO Consultation. WHO Technical Report Series 894. Geneva: World Health Organization, 2000. 26. Horner RL, Mohiaddin RH, Lowell DG, Lowell DG, Shea S, Burman ED. Sites and sizes of fat deposits around the pharynx in obese patients with obstructive sleep apnoea and weight matched controls. European Respiratory J 1989; 2(7): 613-22. 27. Chi L, Comyn FL, Mitra N, Reilly MP, Wan F, Maislin G, Chmiewski L, Thorne-FitzGerald MD, Victor UN, Pack AI, Schwab J. Identification of craniofacial risk factors for obstructive sleep apnoea using three-dimensional MRI. European Respiratory Journal 2011; 38(2): 348-58. 28. Doyle F, Brown J, Lachance C. Relation between bone mass and muscle weight. The lancet 1970; 295(7643): 391-3. J Bagh College Dentistry Vol. 27(2), June 2015 Hard palate bone Pedodontics, Orthodontics and Preventive Dentistry168 29. Gong JK, Arnold JS, Cohn SH. Composition of trabecular and cortical bone. The Anatomical Record 1964; 149(3): 325-331. 30. Guyton AC, Hall JE. Text book of medical physiology. 12th ed. Elsevier 2010. 31. King KS, Lam EW, Faulkner MG, Heo G, Major PW. Vertical bone volume in the paramedian palate of adolescents: a computed tomography study. Am J Orthod Dentofacial Orthop 2007; 132: 783-8. 32. Wehrbein H, Feifel H, Diedrich P. Palatal implant anchorage reinforcement of posterior teeth: a prospective study. Am J Orthod Dentofacial Orthop 1999; 116: 678-86. 33. Bernhart T, Vollgruber A, Gahleitner A, Dortbudak O, Haas R. Alternative to the median region of the palate for placement of an orthodontic implant. Clin Oral Implants Res 2000; 11: 595-601. .Table 1: Comparison between the two groups in bone density (HU) (cortical and cancellous) and bone thickness (mm) measurements. B on e D en si ty Descriptive statistics Male (n=30) Age group difference Female (n=30) Age group difference Group Ι (n=15) Group ΙΙ (n=15) P-value Group Ι (n=15) Group ΙΙ (n=15) P-value C or ti ca l Range 821.00 860.20 0.72 (NS) 936.10 953.00 0.6 (NS) 1287.4 1290.7 1299.5 1131.5 Mean 1121.5 1103.7 1153.1 1131.5 SD 140.65 128.11 113.63 106.72 C an ce llo us Range 546.30 463.30 0.29 (NS) 615.40 539.30 0.12 (NS) 994.40 913.10 1048.3 971.10 Mean 751.70 700.10 782.20 711.20 SD 131.31 128.02 126.48 114.23 B on e th ic kn es s Range 3.9000 5.0000 0.21 (NS) 4.0000 4.2000 0.73 (NS) 9.5000 9.6000 7.5000 7.3000 Mean 6.400 7.1000 5.7000 5.8000 SD 1.4700 1.3700 1.1900 0.9900 Table 2: Gender difference in the bone density (HU) (cortical and cancellous) and bone thickness (mm) measurements of the hard palate. Descriptive statistics Male (n=30) Female (n=30) Gender difference (P-value) B on e D en si ty C or ti ca l Range 821.00 936.10 0.35 (NS) 1290.7 1313.5 Mean 1112.6 1142.3 SD 132.50 108.86 C an ce ll ou s Range 463.30 539.30 0.53 (NS) 994.40 1048.3 Mean 725.90 746.70 SD 130.09 123.79 B on e T hi ck ne ss Range 3.9000 4.0000 0.005 (S) 9.6000 7.5000 Mean 6.7000 5.8000 SD 1.4400 1.0800 J Bagh College Dentistry Vol. 27(2), June 2015 Hard palate bone Pedodontics, Orthodontics and Preventive Dentistry169 Table 3: Gender difference in the bone thickness (mm) of different areas of the hard palate. الخالصة بشكل التقویمیة الزرعات للسماح بوضع مكوناتھو كتلةالجسم دلیل معوعالقتھما العمر من والرابع العقدالثالث خاللالحنك الصلب كثافة وسمك عظملتقییم :الخلفیة .أكثر دقة الحنك الصلب وسمكھ كثافة عظم. سنة٢٩-٢٠تتراوحأعمارھمبین) ناثاأل من٣٠منالذكورو٣٠(شخص ٦٠المفراس الحلزوني لجمعت صور :المواد واألدوات من الثقب الحاد والدرز الحنكي الوسطي )ملیمیتر( ٣و ٦موقع عند تقاطع خمس خطوط إشارة أمامیة خلفیةمع أربع خطوط إشارة قریبة جانبیة بمسافة ٢٠قیست ل الماء والعضالت؛ كتلة العظم ،كھربائیة استخدم لقیاس وزن الجسم؛ النسبة المئویة لدھون الجسمالمیزان التشخیصیالذي یعمل بمبدء تحلیل الممانعة ال.على التوالي .النشیطة األساسیة والنسبةاألیضیة والنسبةاألیضیة ینبغیالنظرفیالجنسینفیمایتعلقبسماكةعظم . الحنك الصلب وسمكھ الكلیة خالل العقد الثالث والرابع من العمر كثافةعظم في إحصائیة داللة ذات التوجدفروق:النتائج بالنسبة للمناطق القریبة الجانبیة، . آبینت میول للتزاید خلفی اإلسفنجيبینما كثافة العظم ،آبینت كثافة العظم القشري وسمك العظم میول للتناقص خلفی. الحنك الصلب كثافة العظموسمك العظم أن العالقة بینلقد تبین .تحدث مع الزیادة في دلیل كتلة الجسم كثافة العظم القشريأن ھنالك تزاید في لقدلوحظ. لم یالحظ نموذج مخصص .إحصائیة داللة ذاتمع قیاسات المیزان التشخیصي معظمھا لیست لسمك العظم یجب توخي الحذر عند التخطیط آوفق بینما ،كثافة العظمل آالحنك الصلب وفقالزرعات التقویمیة من الممكن وضعھا في معظم مناطق عظم :االستنتاج تصنیف جدید لسمك عظم الحنك الصلب تم وضعھ. الحنك الصلبعظم الزرعات التقویمیة في لوضع B on e T hi ck ne ss Areas Descriptive Statistics Male (n=30) Female (n=30) Gender difference (P-value) A nt er op os te ri or A re as Anterior Area Range 5.10 6.40 0.002 (HS) 15.2 12.3 Mean 10.3 8.70 SD 2.15 1.65 Middle Area Range 2.50 2.20 0.06 (NS) 8.10 7.00 Mean 5.00 4.30 SD 1.49 1.20 Posterior Area Range 2.30 2.10 0.11 (NS) 6.0 6.30 Mean 4.00 3.50 SD 1.22 0.94 M ed io la te ra l A re as Mid-Palatal Area Range 6.10 5.10 0.013 (HS) 12.00 10.3 Mean 8.60 7.70 SD 1.55 1.30 Medial Area Range 3.60 3.10 0.028 (HS) 9.80 7.80 Mean 6.30 5.40 SD 1.66 1.30 Middle Area Range 2.80 2.70 0.003 (HS) 8.30 6.70 Mean 5.70 4.60 SD 1.43 1.09 Lateral Area Range 3.30 3.00 0.012 (HS) 9.10 8.80 Mean 6.30 5.30 SD 1.63 1.38 J Bagh College Dentistry Vol. 27(2), June 2015 Hard palate bone Pedodontics, Orthodontics and Preventive Dentistry170 Table 4: Comparisons between the areas of the hard palate in bone density (HU). Descriptive statistics Areas Mean difference Cohen s d P- value Anterior Middle A nt er op os te ri or a re a B on e D en si ty Cortical Mean 1246.4 1104.8 141.6 1.06 (LE) 0.001 (HS) SD 113.55 150.40 Cancellous Mean 633.20 775.30 -142.1 -0.83 (LE) 0.001 (HS) SD 124.50 207.44 Anterior Posterior B on e D en si ty Cortical Mean 1246.4 1019.8 226.6 1.63 (LE) 0.001 (HS) SD 113.55 160.78 Cancellous Mean 633.20 819.80 -186.6 -1.25 (LE) 0.001 (HS) SD 124.50 169.70 Middle Posterior B on e D en si ty Cortical Mean 1104.8 1019.8 85.00 0.55 (ME) 0.001 (HS) SD 150.40 160.78 Cancellous Mean 775.30 819.80 -44.50 -0.23 (SE) 0.2 (NS) SD 207.44 169.70 M ed io la te ra l a re as Mid-Palatal Medial B on e D en si ty Cortical Mean 1099.6 1183.3 -83.7 -0.6 (ME) 0.001 (HS) SD 116.70 160.78 Cancellous Mean 832.90 637.90 195 1.22 (LE) 0.001 (HS) SD 112.38 195.51 Mid-Palatal Middle B on e D en si ty Cortical Mean 1099.6 1113.2 -13.6 -0.09 (SE) 1 (NS) SD 116.70 165.76 Cancellous Mean 832.90 757.30 75.6 0.47 (ME) 0.028 (HS) SD 112.38 199.30 Mid-Palatal Lateral B on e D en si ty Cortical Mean 1099.6 1113.6 -14.00 -0.11 (Small effect) 1 (NS) SD 116.70 144.99 Cancellous Mean 832.90 717.00 115.9 0.79 (ME) 0.001 (HS) SD 112.38 174.40 Medial Middle B on e D en si ty Cortical Mean 1183.3 1113.2 70.10 0.43 (ME) 0.002 (HS) SD 160.78 165.76 Cancellous Mean 637.90 757.30 -119.4 -0.6 (ME) 0.001 (HS) SD 195.51 199.30 Medial Lateral B on e D en si ty Cortical Mean 1183.3 1113.6 69.7 0.46 (ME) 0.006 (HS) SD 160.78 144.99 Cancellous Mean 637.90 717.00 -79.1 -0.43 (ME) 0.041 (HS) SD 195.51 174.40 Middle Lateral B on e D en si ty Cortical Mean 1113.2 1113.6 -0.40 0 (NE) 1 (NS) SD 165.76 144.99 Cancellous Mean 757.30 717.00 40.3 0.22 (SE) 0.41 (NS) SD 199.30 174.40 J Bagh College Dentistry Vol. 27(2), June 2015 Hard palate bone Pedodontics, Orthodontics and Preventive Dentistry171 Table 5: Comparisons between the areas of the hard palate in bone thickness (mm) for male and female. Descriptive Statistics Areas for male Mean difference Cohen s d P- value Areas for female Mean difference Cohen s d P- value Anterior Middle Anterior Middle A nt er op os te ri or A re as Mean 10.3 5.00 5.3 2.86 (LE) 0.001 (HS) 8.70 4.30 4.4 3.o6 (LE) 0.001 (HS) SD 2.15 1.49 1.65 1.20 Anterior Posterior Anterior Posterior Mean 10.3 4.00 6.3 3.60 (LE) 0.001 (HS) 8.70 3.50 5.2 3.88 (LE) 0.001 (HS) SD 2.15 1.22 1.65 0.94 Middle Posterior Middle Posterior Mean 5.00 4.00 1.0 0.74 (ME) 0.001 (HS) 4.30 3.50 0.8 0.74 (ME) 0.001 (HS) SD 1.49 1.22 1.20 0.94 Mid-Palatal Medial Mid- Palatal Medial M ed io la te ra l A re as Mean 8.60 6.30 2.3 1.43 (LE) 0.001 (HS) 7.70 5.40 2.3 1.77 (LE) 0.001 (HS) SD 1.55 1.66 1.30 1.30 Mid-Palatal Middle Mid- Palatal Middle Mean 8.60 5.70 2.9 1.95 (LE) 0.001 (HS) 7.70 4.60 3.1 2.58 (LE) 0.001 (HS) SD 1.55 1.43 1.30 1.09 Mid-Palatal Lateral Mid- Palatal Lateral Mean 8.60 6.30 2.3 1.45 (LE) 0.001 (HS) 7.70 5.30 2.4 1.79 (LE) 0.001 (HS) SD 1.55 1.63 1.30 1.38 Medial Middle Medial Middle Mean 6.30 5.70 0.6 0.39 (ME) 0.001 (HS) 5.40 4.60 0.8 0.67 (ME) 0.001 (HS) SD 1.66 1.43 1.30 1.09 Medial Lateral Medial Lateral Mean 6.30 6.30 0.0 0.0 (NE) 1 (NS) 5.40 5.30 0.1 0.07 (SE) 1 (NS) SD 1.66 1.63 1.30 1.38 Middle Lateral Middle Lateral Mean 5.70 6.30 -0.6 -0.39 (ME) 0.001 (HS) 4.60 5.30 -0.7 0.56 (ME) 0.001 (HS) SD 1.43 1.63 1.09 1.38 Table 6: The relationship of the bone density (cortical and cancellous) and bone thickness (for male and female) with BMI. Descriptive statistics BMI (Kg/m2)-categories ANOVA trendP-value Normal (18.5-24.9) Overweight (25-29.9) Obese (≥30) B on e D en si ty C or ti ca l n=60 n=24 n=23 n=13 0.016 (S) Range 821.00 860.20 1026.3 1313.5 1299.5 1290.7 Mean 1091.1 1129.5 1190.8 SD 137.00 111.30 80.600 C an ce llo us n=60 n=24 n=23 n=13 0.22 (NS) Range 463.30 586.40 605.00 994.40 1048.3 913.10 Mean 708.50 750.20 763.00 SD 146.80 113.60 104.20 B on e T hi ck ne ss M al e n=30 n=16 n=7 n=7 0.76 (NS) Range 3.9 5.8 5.2 9.5 9.6 8.2 Mean 6.5 7.1 6.7 SD 1.6 1.4 1.3 F em al e n=30 n=8 n=16 n=6 0.78 (NS) Range 4.9 4.0 4.1 7.5 7.5 7.3 Mean 6.0 5.6 5.9 SD 1.0 1.1 1.1 J Bagh College Dentistry Vol. 27(2), June 2015 Hard palate bone Pedodontics, Orthodontics and Preventive Dentistry172 Table 7: The Relationship of the bone density (cortical and cancellous) and bone thickness with diagnostic scale measurements. Descriptive statistics Variables Fat% Water% Muscle% Bone Mass BMR AMR C or ti ca l B on e D en si ty Lowest quartile (≤1042.5) n=15 Mean 27.5 52.9 39.3 10.0 1709.3 2380.4 SD 5.70 4.16 4.54 2.46 243.79 379.23 Interquartile range (1042.6 – 1209.7)n=30 Mean 29.3 51.6 37.7 9.10 1649.9 2260.4 SD 8.11 5.92 6.09 2.30 253.14 376.68 Highest quartile (1209.8 ) n=15 Mean 29.3 52.2 37.7 9.20 1644.3 2276.8 SD 7.15 6.19 5.51 2.26 229.98 381.53 P-Value (ANOVA Trend) 0.5 (NS) 0.73 (NS) 0.46 (NS) 0.37 (NS) 0.47 (NS) 0.46 (NS) C an ce llo us B on e D en si ty Lowest quartile (≤638.1) n=15 Mean 30.1 51.0 37.7 9.80 1699.7 2344.2 SD 7.08 5.17 5.65 2.95 334.08 487.39 Interquartile range (638.2 – 833.4) n=30 Mean 30.0 51.0 37.1 9.30 1654.6 2285.0 SD 6.58 5.17 5.04 2.17 214.86 333.72 Highest quartile (833.5 ) n=15 Mean 25.4 55.1 40.5 9.10 1644.5 2263.7 SD 8.10 6.51 6.07 1.98 197.23 349.18 P-Value (ANOVA Trend) 0.07 (NS) 0.043 (S) 0.16 (NS) 0.39 (NS) 0.54 (NS) 0.56 (NS) B on e T hi ck ne ss Lowest quartile (≤5.1)n=15 Mean 29.0 52.4 37.0 8.30 1548.1 2104 SD 8.23 6.85 6.13 1.67 154.33 271.67 Interquartile range (5.2 – 7.2) n=30 Mean 28.8 52.0 38.2 9.40 1667.8 2309.4 SD 7.01 5.11 5.47 2.22 236.86 368.72 Highest quartile (7.3 ) n=15 Mean 28.8 52.0 39.1 10.5 1769.7 2455.1 SD 7.29 5.32 5.27 2.68 285.79 414.22 P-Value (ANOVA Trend) 0.93 (NS) 0.84 (NS) 0.32 (NS) 0.009 (HS) 0.012 (S) 0.01 (S) Table 8: Classification of bone density and thickness of hard palate for the anteroposterior areas. Anterioposterior Areas Descriptive Statistics Bone Density Bone Thickness Cortical Cancellous Male Female Anterior Area Range D2-D1 D3-D2 T3-T1 T3-T2 Mean D2 D3 T2 T2 Middle Area Range D3-D1 D3-D2 T4-T2 T4-T2 Mean D2 D3 T3 T3 Posterior Area Range D3-D2 D3-D2 T4-T3 T4-T3 Mean D2 D3 T3 T4 Table 9: Classification of bone density and thickness of hard palate for the mediolateral areas. Mediolateral Areas Descriptive Statistics Mid-Palatal Area Medial Area Middle Area Lateral area B on e D en si ty Cortical Range D3-D1 D3-D1 D3-D1 D3-D1 Mean D2 D2 D2 D2 Cancellous Range D3-D2 D4-D2 D3-D2 D4-D2 Mean D3 D3 D3 D3 B on e T hi ck ne ss Male Range T3-T2 T4-T2 T4-T2 T4-T2 Mean T2 T3 T3 T3 Female Range T3-T2 T4-T2 T4-T3 T4-T2 Mean T3 T3 T3 T3