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A COMPARATIVE ANALYSIS OF MANDIBULAR AND CALCANEAL BONE MINERAL DENSITY IN POST–MENOPAUSAL WOMEN

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KAUNAS UNIVERSITY OF MEDICINE

Eglė Jagelavičienė

A COMPARATIVE ANALYSIS

OF MANDIBULAR AND CALCANEAL

BONE MINERAL DENSITY

IN POST–MENOPAUSAL WOMEN

Summary of the Doctoral Dissertation Biomedical Sciences, Odontology (08 B)

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The doctoral dissertation has been prepared at Kaunas University of Medicine in 2005–2010.

Scientific Supervisor:

Prof. Dr. Habil. Ričardas Kubilius (Kaunas University of Medicine, Biomedical Sciences, Odontology – 08 B)

Scientific Consultant:

Dr. Aurelija Krasauskienė (Kaunas University of Medicine, Biomedical Sciences, Medicine – 07 B)

The dissertation will be defended at the Research Council of Odontology Sciences, Kaunas University of Medicine.

Chairwoman

Prof. Dr. Vita Mačiulskienė (Kaunas University of Medicine, Biomedical Sciences, Odontology – 08 B)

Members:

Prof. Dr. Algidas Basevičius (Kaunas University of Medicine, Biomedical Sciences, Medicine – 07 B)

Dr. Rimantas Žalinkevičius (Kaunas University of Medicine, Biomedical Sciences, Medicine – 07 B)

Assoc. Prof. Dr. Vytautė Pečiulienė (Vilnius University, Biomedical Sciences, Odontology – 08 B)

Prof. Dr. Alina Pūrienė (Vilnius University, Biomedical Sciences, Odontology – 08 B)

Opponents:

Prof. Dr. Antanas Šidlauskas (Kaunas University of Medicine, Biomedical Sciences, Odontology – 08 B)

Assoc. Prof. Dr. Vidmantas Alekna (Vilnius University, Biomedical Sciences, Medicine – 07 B)

The dissertation will be defended at the open session of the Research Council of Odontology Sciences, Kaunas University of Medicine on the 27th of May 2010, at 10.00 am in the auditorium of the Clinic of Orthodontics, Kaunas University of Medicine.

Address: Lukšos–Daumanto 6, LT– 50106 Kaunas, Lithuania. The summary of the dissertation was sent on the 27th of April 2010.

Review of the dissertation is available in the Library of Kaunas University of Medicine

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KAUNO MEDICINOS UNIVERSITETAS

Eglė Jagelavičienė

POMENOPAUZINIO AMŽIAUS MOTERŲ

APATINIO ŽANDIKAULIO IR KULNAKAULIO

KAULŲ MINERALŲ TANKIŲ PALYGINAMOJI

ANALIZĖ

Daktaro disertacijos santrauka

Biomedicinos mokslai, odontologija (08 B)

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Disertacija rengta 2005–2010 metais Kauno medicinos universitete Mokslinis vadovas:

Prof. habil. dr. Ričardas Kubilius (Kauno medicinos universitetas, biomedicinos mokslai, odontologija – 08 B)

Konsultantas:

Dr. Aurelija Krasauskienė (Kauno medicinos universitetas, biomedicinos mokslai, medicina – 07 B)

Disertacija ginama Kauno medicinos universiteto Odontologijos mokslo krypties taryboje.

Pirmininkė

Prof. dr. Vita Mačiulskienė (Kauno medicinos universitetas, biomedicinos mokslai, odontologija – 08 B)

Nariai:

Prof. dr. Algidas Basevičius (Kauno medicinos universitetas, biomedicinos mokslai, medicina – 07 B)

Dr. Rimantas Žalinkevičius (Kauno medicinos universitetas, biomedicinos mokslai, medicina – 07 B)

Doc. dr. Vytautė Pečiulienė (Vilniaus universitetas, biomedicinos mokslai, odontologija – 08 B)

Prof. dr. Alina Pūrienė (Vilniaus universitetas, biomedicinos mokslai, odon-tologija – 08 B)

Oponentai:

Prof. dr. Antanas Šidlauskas (Kauno medicinos universitetas, biomedicinos mokslai, odontologija – 08 B)

Doc. dr. Vidmantas Alekna (Vilniaus universitetas, biomedicinos mokslai, medicina – 07 B)

Disertacija bus ginama viešame Odontologijos mokslo krypties tarybos posėdyje 2010 m. gegužės 27 d. 10 val. Kauno medicinos universiteto Ortodontijos klinikos auditorijoje.

Adresas: Lukšos–Daumanto 6, LT–50106, Kaunas, Lietuva. Disertacijos santrauka išsiųsta 2010 m. balandžio 27 d.

Disertaciją galima peržiūrėti Kauno medicinos universiteto bibliotekoje Adresas: Eivenių 6, LT – 50161 Kaunas, Lietuva.

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ABBREVIATIONS

BMD – Bone Mineral Density BMM – Bone Mineral Mass

DXA – Dual X–ray Energy Absorptiometry

DXL – Dual X–ray Energy and Laser Osteodensitometry CT – Quantitative Computed Tomography

PI – Periodontal Index according to Russell MI – Mental Index

PMI – Panoramic Mandibular Index

MCI – Mandibular Cortical Index according to Klemetti MRI (AB/MB ratio) – Mandibular Ratio Index

OD MCB – Optical density of the mandibular cortical bone OD MTB – Optical density of the mandibular trabecular bone C – Mandibular Cortical Width

SD – Standard Deviation CI – Confidence Interval

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1. INTRODUCTION

Aging of the population accompanied by chronic diseases ranks among the major issues of the 21st century, which makes the studies of factors that help to identify and stave off such diseases a necessity (Alekna, 2008). Osteoporosis is a chronic disease that develops in the bone tissue of the skeleton. This condition is common among a significant part of the elderly population – especially among postmenopausal women. 2.5 million bone fractures occur yearly due to osteoporosis. It is prognosticated that this figure is likely to increase. 250.000 people in Lithuania have osteoporosis.

The mandibular bone is a part of the bony structure of the skeleton. Older age is characterized by resorption of the jawbones and morphologic dimensional changes in the cortical bone. Over the last decades, researches have proven the existence of a relationship between mandibular bone mineral density, the mandibular body height, the number of teeth, and changes in the general skeletal bone mineral density; some authors think this relationship to be especially strong (Bollen, 2000; Nakamoto, 2003), while others state that it is not so reliable (Law, 1996; Mohajery, 1992). Skeletal bones differ in their anatomical structure due to differing distributions of cortical and trabecular bone. In addition to that, a reduction in bone mineral density in different bones during various periods of life occurs at different rates and is affected by a variety of factors. The studied populations differ in their geographic place of residence, lifestyle, nutrition, peculiarities of physical activity, and education – all this affects the metabolic processes in the bones.

Bone changes in the mandible and osteoporosis of the skeleton share many risk factors, such as age, menopause, race, genetic factors, and smoking, consumption of calcium and medications, and family history. Literature sources provide information about panoramic radiographic examinations of the mandible that allow for the calculation of the panoramic radiomorphometric indices of the mandible determining its bone mineral density, as well as on the comparisons of bone mineral density in various bones of the skeleton (Benson, 1991; Devlin, Horner, 2002; Dutra, 2005; Ledgerton, 1999). The findings that are most commonly compared are those of the mandible and dual X–ray energy absorptiometry (DXA) of the lumbar spine or the hip bone, ultrasound of the calcaneus, and osteodensitometry of the wrist. Sometimes findings obtained in different populations are contradictory.

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The majority of older people visit their odontologists due to periodontal diseases. The patients undergo panoramic radiography for the evaluation of the periodontal status, alveolar bone height, and the number of remaining teeth. However, it is equally important to know what changes in the mandibular bone on the panoramic radiograms indicate general osteopenia of the skeletal system and suggest osteoporosis.

Clinicians pointed to the panoramic radiographic examinations performed by odontologists and the resulting panoramic radiomor-phometric indices (MCI, MI, and PMI) as diagnostic criteria for the selection of elderly patients who need to undergo BMD examinations (Tözüm, 2004). Such clinical examinations are especially developed in Japan. The data of Japanese scientists showed that in several clinics the examination of the mandibular cortical bone showed that 95% of female patients had reduced BMD (Taguchi, 2009). In Lithuania such techniques are not yet applied, but joint efforts of clinicians and odontologists in treating reduced bone mineral density would yield good results.

Frequent use of panoramic radiography in odontology stimulated to initiate studies of the mandible, at the same time the new device DXL Calscan stimulated measurements of calcaneus BMD – however the possible relationship of BMD changes in these two bones were not yet identified in researches. The mandible and calcaneus are functionally active bones. Although these bones differ in their anatomical structure (cortical bone predominates in the mandible, while trabecular bone – in the calcaneus), because of continuous load both bones maintain the solidity of the bone. However, some risk factors – such as changes related to age and the menopause – create the conditions for the development uneven bone resorption in these bones.

Two most easily accessible techniques were selected for bone mineral density studies – panoramic radiography of the mandible (an inexpensive, informative, and most commonly used technique for the examination of jawbones and teeth) and DXL of the calcaneus. DXL Calscan is a device used exclusively for bone mineral density measurements in the calcaneus. In 2004, this device was approved by the NOS for diagnostic studies (Black, 2005). A combination of X–ray and laser measures bone mineral density irrespectively of the amount of soft tissue, and does not evaluate additional foci of calcification that may occur while examining the spine and the hip (osteochondrosis, discopathy, osteoarthrosis, or calcified blood vessels). The device is portable and inexpensive, compared to DXA examinations; besides, the topographic anatomy of the measured site is

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convenient and does not require any special preparation of the patient. Literature sources indicate good comparability of the findings of bone mineral density of the calcaneus obtained via this technique and the results of bone mineral density measurements in the spine and the femur obtained by applying DXA (Kullenberg, 2003). No data in the analyzed scientific literature were found on bone mineral density measurements in the calcaneus by applying DXL or the relationship of such measurements with the respective findings in the mandible (panoramic radiomorphometric indices).

Additional knowledge on bone mineral density (BMD) in jawbones would allow odontologists to apply diagnostic mandibular BMD criteria characteristic of our population in analyzing panoramic radiography images, and to use this information in periodontology, implantology, and oral surgery. This would allow for a timely referral of the patient by his/her odontologist to general practitioners or specialists for consultations, as well as for the implementation of osteoporosis prevention projects.

1.1. AIM OF THE STUDY

To examine mandibular bone mineral density using panoramic radio-graphy, to evaluate its effect on the number of remaining teeth and the mandibular body height, and to determine the relationship of the pano-ramic radiomorphometric indices of the mandible with calcaneal bone mineral density in post–menopausal women.

1.2. OBJECTIVES OF THE STUDY

1. To analyze the relationship between the panoramic radiomorpho-metric indices of the mandible indicating mandibular bone mineral density, the optical density of the mandibular bone in panoramic radiography images, and bone mineral density of the calcaneus.

2. To use panoramic radiomorphometric indices of the mandible and densitometry examination to calculate mandibular bone mineral density, to determine its relationship with the number of remaining teeth and the mandibular body height, and to evaluate diagnostic effectiveness of panoramic radiomorphometric indices.

3. To evaluate the effect of changes in mandibular bone mineral density on periodontal tissues.

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4. To determine the effect of calcaneal (the general skeletal) bone mineral density on the number of remaining teeth and mandibular body height.

5. To evaluate the relationship of age and the post–menopausal period with bone mineral density in the calcaneus and the mandible, mandibular body height, and the number of remaining teeth.

6. To perform in vitro morphometric analysis of the mandibular cortical bone, and to evaluate the reliability of panoramic radiography in the examination of cortical bone in the mandibular base.

1.3. NOVELTY OF THE STUDY

The following was performed:

– a comparative BMD analysis in two bones characterized by high functional activity – the mandible and the calcaneus – determining the relationship between these bones as parts of the general skeletal BMD, and the effect of this relationship on the morphometric changes in the cortical bone of the mandibular base, the number of remaining teeth, and the mandibular body height;

– in vitro analysis of mandibular cortical width at the mental foramen using different examination techniques;

– evaluation of the cortical/trabecular bone ratio in the mandibular base with subsequent selection of the margins for the measurements of cortical width in the mandibular base on panoramic radiography images, and in vitro determination of changes in the cortical width of the mandibular base at the mental foramen with respect to the panoramic radiograph magnification factor;

– analysis of panoramic radiomorphometric indices and the optical density in digitized panoramic radiography images using computer software.

1.4. PRACTICAL SIGNIFICANCE

The study allowed for evaluating the diagnostic efficiency of panoramic radiomorphometric indices in detecting changes in mandibular BMD, as well as for identifying the significance of these indices and possibilities for their use. Mandibular BMD calculated using these indices would help to plan odontological treatment and its outcomes, and to improve prognostic markers in periodontology, oral surgery, and implantology; furthermore,

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BMD calculated using this technique may serve as an practical recommen-dation and a patient selection criterion for panoramic radiography image– based identification of patients with reduced BMD who would benefit from timely referral to bone mineral density examination and treatment of osteoporosis. Osteoporotic processes detected during calcaneal BMD examinations affect mandibular BMD. In addition to contributing to the knowledge about the general metabolic processes occurring in the skeleton, these results also proved to be practical and significant in the general clinical treatment of osteoporosis.

2. MATERIALS AND METHODS

The study included post–menopausal women aged 50–77 years who presented to Kaunas University of Medicine Clinic of Dental and Oral Pathology with periodontal disease. The subjects’ health status was good or satisfactory; they had no diseases leading to secondary osteoporosis, had used no hormone preparations or medications that could affect bone metabolism for one year, had no diseases of oral mucosa, dentate man-dible, were non–smokers, and did not use alcohol. The main exclusion criteria were lack of motivation, surgical treatment of the mandible and periodontal tissues undergone within the previous 6 months, and restoration of the mandibular function via implants.

2.1. Methods

The subjects underwent clinical odontological examination, panoramic radiography, and DXL of the calcaneus.

Clinical odontological examination

During the examination we determined the number of the remaining teeth, evaluated the degree of their mobility (according to Egelberg, Badersten, 1994), and measured the depth of periodontal pockets; the periodontal score was calculated using the progressive scale for the evaluation of the condition of supportive dental tissues (according to Russell, 1954).

Panoramic radiographic examination and measurements

Panoramic radiography was performed in the X–ray laboratory of Kaunas University of Medicine Clinic of Dental and Maxillofacial

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Orthopedics using a panoramic radiograph PC –1000 Panoramic X–ray (Panoramic corporation, Dentalcompare, USA, 1997); the patients were correctly positioned following the technique described by Dutra (Dutra, 2005). The panoramic radiography images were marked with a code, scanned using a scanner (VIDAR Systems Corporation, 2006, USA), and were digitized at 300 dpi resolution and 8 bits/pixel grayscale format by applying a logarithmical algorithm. Panoramic radiomorphometric linear and densitometry measurements were performed on the left and the right side of the mandibles at the mental foramen using the medical image analysis software Osiris Medical imaging software 2002 (Osiris Version 3.12) and MedCals Software © 2005– 2007 Frank Schoonjans Digimizer (Version 3.0.0.0). To increase the accuracy of the study, an odontologist performed triple measurements of the obtained images, and two independent researchers with experience in radiology performed additional measurements (one each).

The following characteristics were analyzed in panoramic radiography images:

1. AB – the distance between the upper margin of the alveolar part of the mandible and the lower margin of the mandibular base (mm) (accord-ing to Ledgerton, 1997);

2. MB – the distance between the center of the mental foramen of the mandible and the lower margin of the mandibular base (mm) (according to Ledgerton, 1997; Taguchi, 1995);

3. C – cortical width in the mandibular base at the mental foramen (mm) (Mental Index (MI)) (according to Ledgerton, 1997);

4. OD MCB – optical density in the mandibular cortical bone (according to Knezović Zlataric and Čelebic, 2003);

5. OD MTB – optical density in the mandibular trabecular bone (according to Knezović Zlataric and Čelebic, 2003);

6. The morphological changes of the inner margin of the cortical bone of the mandibular base distally from the mental foramen (Mandibular Cortical Index (MCI) according to Klemetti, 1994).

The following panoramic indices were calculated:

1. The Panoramic Mandibular Index (PMI) (according to Benson, 1991) (C/MB);

2. The Mandibular Resorption Index (MRI) (according to Wical and Swoope, 1974) (AB/MB).

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The examination of the mandibles (in vitro) was performed on 28 anatomic mandibles supplied by the archive of the Department of Anatomy, Histology and Anthropology (Vilnius University). The following equipment was used for the study: a panoramic radiograph PC – 1000 Panoramic X– ray (Panoramic corporation, Dentalcompare, USA, 1997; a scanner VIDAR Systems Corporation, 2006, USA; medical image analysis software Osiris Medical imaging software 2002 (Osiris Version 3.12) and MedCals Software © 2005 –2007 Frank Schoonjans Digimizer (Version 3.0.0.0)), computer multilayer spiral tomograph Multisync LCD 18805X Light speed ™ Pro16 (General Electric Company, USA, 2003), and an endodontic ruler. We performed morphometric studies of the mandibles and a visual analysis of the cortical/trabecular bone ratio in the mandibular base, and specified the margins of cortical bone measurements and the magnification coefficient of the panoramic radiograph.

DXL Calscan osteodensitometry

Calcaneal bone mineral density (BMD) was examined at Kaunas University of Medicine Institute of Endocrinology by applying dual X–ray energy and laser osteodensitometry using DXL Calscan P/N 031000 (Demetech AB, Solna, Sweden). The DXL Calscan software calculates the results of calcaneal BMD measurements in g/cm², bone mineral mass – in g, the measurement area – in cm², and mean external calcaneal thickness – in mm, and also presents the expression of T and Z scores. The examination was performed by a physician endocrinologist.

Following the diagnostic criteria for osteoporosis recommended by the World Health Organization (1994), the subjects were distributed according to the bone mineral density T score into the normal bone mineral density (T score >–1), osteopenia (T score ≤–1 to >–2.5), and osteoporosis (T score ≤–2.5) groups.

2.2. STATISTICAL ANALYSIS OF THE DATA

Statistical data analysis was performed using the standard software packages “Statistica 5.5”, “Excel 2000”, and “SPSS 13.0”. Coded data on the patients were used in the analysis.

The sample volume was calculated during a pilot study. The power of the study was selected to be β=0.8, and the confidence level – α=0.05.

Continuous values were evaluated using the following statistical characteristics: mean, median, and standard deviation (SD). The

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Kolmogorov–Smirnov test was used to verify the normal distribution of quantitative values. When the sample size was sufficient and the distribution was normal, differences between mean values of two groups for independent samples were compared by applying Student’s (t) criterion. When the samples were small (n<20), the values were non– parametric, or the distribution did not meet the normal distribution requirements, differences between mean values were compared by applying the Mann–Whitney U test. Mean values of several groups and dispersions of these mean values were compared by applying the single– factor dispersion analysis (ANOVA). The dependence of attributes was evaluated using Pearson’s correlation coefficient (r) and the regression line. The correlation coefficient r indicated the strength of the linear relationship: if r≤0.3, the relationship was weak, if 0.3≤ r ≥0.8 – moderate, and if 0.8≤ r ≥1 − strong. Frequencies were compared using chi–square (χ2). When the numeral expression of the evaluated values in each cell was <5, of Fischer’s exact probability t criterion was applied.

Logistic regression analysis was performed in order to evaluate the diagnostic criteria of mandibular indices. Prior to the ROC curve analysis, the data were included on the basis of calcaneal T score groups, where T2+T3 groups corresponded to the logical unit, and group T1 – to the control group. The sensitivity and specificity of indices were determined on the basis of the ROC (receiver operator characteristic) curves. The diagnostic value of the study was determined by calculating the area under the ROC curve. If the area under the curve was 0.9–1 – the diagnostic value of the study was excellent, if 0.8–0.9 – very good, if 0.7–0.8 – good, if 0.6–0.7 – satisfactory, and if 0.5–0.6 – unsatisfactory.

The significance level of 0.05 was selected in the verification of statistical hypotheses.

3. RESULTS

129 post–menopausal women aged 50–77 years (mean age (±SD) – 62.50±6.13) mined at Kaunas University of Medicine Clinic of Dental and Oral Pathology and Institute of Endocrinology. As the analysis of socio– demographic data showed that 95.34% of the subjects (n=123) lived in cities, and 71 (55.03%) had higher education level (of these, 21.3% had normal bone mineral density, 53.52% – decreased BMD, and 25.35% had osteoporosis). 104 (80.6%) subject indicated normal onset of the post– menopausal period; of these, 26 (76.47%) had normal BMD, 53 (81.54%) had osteopenia, and 25 (86.21%) had osteoporosis.

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118 out of 129 examined women (91.47%) had not been treated with corticosteroids, and 11 (8.53%) women stated that they had used them at some point in their lives (group T1, n=2 (18.18%); group T2, n=6 (54.55%); and group T3, n=3 (27.27%). 106 (82.17%) subjects had never used osteoclast inhibitors, and 23 stated that they had been treated with such preparations several years prior to the study. The latter belonged to group T2 (n=11; 47.83%) and group T3 (n=12; 52.17%). The majority of the respondents (82 women, 52% of which were diagnosed with reduced BMD (osteopenia)) stated that their use of calcium preparations was not regular.

The investigation of the subjects’ physical activity showed that 98 (75.96%) were physically active for over one hour per day, while in the rest of the subjects, the duration of physical activity ranged from 15 to 60 minutes per day.

3.1. Bone mineral density measurements in calcaneus

After the evaluation of calcaneal BMD according to the T score values, the 129 subjects were distributed into 3 groups: group T1, n=34 (26%) comprised subjects with normal BMD, group T2, n=65 (50%) – subjects with osteopenia, and group T3, n=30 (23%) – those with osteoporosis. The general mean value of T score (±SD) was –1.62±1.12; the lowest value was –4.30, and the highest 1.00. The following mean T score values were obtained in the groups: group T1 (mean±SD) –0.13±0.55; group T2 (mean±SD) –1.77±0.43; and group T3 (mean±SD) –2.96±0.48. The difference in T scores between subject groups according to ANOVA was F=289.26; df=2; p<0.001 [T1 vs T2 p<0.001; T1 vs T3 p<0.001; T2 vs T3 p<0.001].

Mean calcaneal BMD (±SD) in the general population of the subjects was 0.38±0.07 (g/cm²); mean value (±SD) in group T1 was 0.47±0.04 (g/cm²); in group T2 – 0.37±0.03 (g/cm²); and in group T3 – 0.29±0.03 (g/cm²). The difference in bone mineral density between the groups was determined by applying ANOVA (F=285.31; df=2; p<0.001) [T1 vs T2 p<0.001; T1 vs T3 p<0.001; T2 vs T3 p<0.001].

Mean calcaneal bone mineral mass (±SD) in the general population of the subjects was 1.95±0.41 (g); mean calcaneal BMD in group T1 (±SD) was 2.46±0.25 (g); in group T2 (±SD) – 1.89±0.19 (g); and in Group T3 (±SD) – 1.48±0.23 (g). Differences in mean calcaneal BMD (±SD) were analyzed using ANOVA (F=168; df=2; p<0.001) [T1 vs T2 p<0.001; T1 vs T3 p<0.001; T2 vs T3 p<0.001].

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The general mean duration of the post–menopausal period (±SD) was 12.53±6.49 years; in group T1 − 8.35±5.40 years; in group T2 − 12.76±5.34 years; and in group T3 − 16.8±7.12 years. Differences in the duration of the post–menopausal period between the groups were analyzed using ANOVA: F=16.92; df=2; p<0.001 [T1 vs T2 p<0.001; T1 vs T3 p<0.001; T2 vs T3 p<0.01].

The distribution of mean age in the groups according to the calcaneal T score was the following: the mean age (±SD) of patients with normal BMD was 59.38±6.37 years and of patients with osteopenia – 62.31±5.00 years. The highest mean age (±SD) was found in patients with osteoporosis − 66.42±6.05 years. Differences in the mean age (±SD) between the groups were evaluated by using ANOVA (F=12.51; df=2; p=0.001) [T1 vs T2 p<0.05; T2 vs T3 p<0.001; T1 vs T3 p<0.001].

Calcaneal BMD was statistically significantly dependent on the subjects’ age (r=–0.401; p<0.001) and the duration of the post–menopausal period (r=–0.421; p<0.001).

3.2. Clinical odontological examination

The general mean value (±SD) of the PI according to Russell (n=129) was 4.31±1.98; in group T1 (n=34) 4.54±1.93; in group T2 (n=65) 4.18±1.90; and in group T3 (n=30) 4.33±2.05. Differences in the mean values (±SD) of the PI according to Russell between subject groups were analyzed by applying ANOVA: F=0.36; df=2; p>0.05 [T1 vs T2 p=0.399; T1 vs T3 p=0.679; and T2 vs T3 p=0.734].

A weak inverse relationship was detected between the PI according to Russell and MRI (r=–0.211; p<0.05), there was no correlation of the PI according to Russell with MI, PMI, or MCI.

The difference in the number of teeth between the groups was evaluated using ANOVA: F=2.28; df=2; p>0.05 (Table 1).

Table 1. Distribution of the number of teeth examination results in T groups

95% confidence interval of the mean values Group n Number of teeth mean±SD Lower margin Upper margin The lowest value The highest value T1 34 21±5.8 19.08 23.15 2 30 T2 65 22.54±6.06 21.04 24.04 6 32 T3 30 19.83±5.58 17.75 21.92 4 29 Total 129 21.53±5.95 20.50 22.57 2 32 Note: T1vs T2 p=0.256, T1 vs T3 p=0.386, T2 vs T3 p<0.05

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The number of remaining teeth statistically significantly correlated with the following: MI in the general population of the subjects (r=0.339; p<0.001); group T1 (r=0.397; p<0.05); group T2 (r=0,339; p<0.01); PMI in the general population of the subjects (r=0.297; p<0.001); group T1 (r=0.296; p =0.09); group T2 (r=0.333; p<0.01); the duration of the post– menopausal period in the general population of the subjects (r=–0.236; p<0.01); group T1 (r=–0.401; p<0.05); group T3 (r=–0.513; p<0.01); MCI in the general population of the subjects (r=–0.190; p<0.05); group T1(r=– 0.335; p=0.053); group T2 (r=–0.244; p=0.05); and the subjects’ age (r=– 0.226; p=0.01); MRI (r=0.231; p<0.01). No correlation was found between the number of teeth and calcaneal bone mineral density.

3.3. Panoramic radiomorphometric analysis

Linear morphometric measurements of panoramic radiography images of the mandible were performed on the right and the left side of the mandible and were adjusted for the magnification coefficient (0.9) because we found no significant difference between adjusted and non–adjusted measurements (p>0.05). On panoramic radiography images, we measured mandibular body height at the mental foramen (AB), the distance from the center of the mental foramen to the lower margin of the mandibular base (MB), and mandibular cortical width (C). The differences in distances between the studies groups were calculated using ANOVA: AB (F=0.50; df=2; p=0.607); MB (F=2.24; df=2; p=0.110); and C (F=9.98; df=2; p<0.001). Mean values (±SD) of the AB; MB measurements are presented in Table 2.

Table 2. Mean values (±SD) of the measurements of the distance between the

margin of the alveolar part of the mandible and the lower margin of the mandibular base (AB) and the distance from the center of the mental foramen to the lower margin of the mandibular base (MB) in patient groups

95% confidence interval of the mean values Distances Groups mean±SD

(mm) Lower margin Upper margin Differences between mean distances in patient groups T1 29.58±3.50 28.35 30.79 T2 29.76±3.56 28.88 30.64 T3 30.38±2.74 29.35 31.40 T1 vs T2 p=0.796 T1 vs T3 p=0.346 T2 vs T3 p=0.411 AB Total 29.86±3.36 29.27 30.44

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Continuation of Table 2

95% confidence interval of the mean values Distances Groups mean±SD (mm)

Lower margin Upper margin Differences between mean distances in patient groups T1 12.91±1.33 12.12 12.92 T2 13.12±1.38 12.77 13.46 T3 12.92±1.37 12.40 13.43 T1 vs T2 p<0.05 T1 vs T3 p=0.236 T2 vs T3 p=0.497 MB Total 12.91±1.33 12.68 13.14

The distance AB was statistically significantly related to the distance MB (r=0.506; p<0.001), C (r=0.183; p<0.05); and the number of teeth (r=0.341; p<0.001). MB was statistically significantly dependent on C (r=0.234; p<0.01) and the distance AB. In literature, mandibular cortical width at the mental foramen (C) is also called the Mental Index (MI). Its analysis is presented in Tables 3, 4, 6–8.

Table 3. Mean cortical width (±SD) of the mandibular base measured at the

mental foramen

Side of the mandible n Cortical width of the mandibular base, mean±SD (mm)

right 129 3.27±0.97

left 129 3.3±0.97

In measurements of the left and the right side of the mandible p>0.05, the mean value of the findings (±SD) used in the analysis was 3.28±0.96 (mm), the lowest value was 1.46, and the highest – 5.82; mode 2.48; median 3.07. The data are presented in Table 4.

Table 4. Mean cortical width (C) (±SD) of the mandibular base in T groups

Groups n Cortical width of the mandibular base, mean±SD (mm) T1 34 3.69±0.98 T2 65 3.34±0.93 T3 30 2.69±0.72 Total 129 3.28±0.96 T2 + T3 95 3.14±0.91 Note. T1 vs T2 p=0.069; T1 vs T3 p<0.001; T2 vs T3 p<0.001.

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We evaluated the accuracy of data provided by the person performing the study (researcher I) and two independent researchers (II and III) and calculated coefficients of variation (CV): distance AB measurements: researcher I – 14.59%; researcher II – 15.67% ; and researcher III – 15.61% ; distance MB measurements: researcher I – 11.46%; researcher II – 11.70%; and researcher III – 11.51%; C measurements: researcher I – 32.72%; researcher II – 32.60%; and researcher III – 33.86%.

Mandibular cortical width (C) was statistically significantly related to the distances AB and MB and the number of teeth (r=0.339; p<0.001); calcaneal bone mineral density (r=0.356; p<0.001); the duration of the post–menopausal period (r=–0.364; p<0.001); MCI (r=–0.580; p<0.001).

Using the data obtained from the measurements, we calculated the Panoramic Mandibular Index (PMI). MI and PMI were statistically significantly interrelated (r=0.931; p<0.001). PMI differences between the subject groups were calculated using ANOVA (F=12.06; df=2; p<0.001). The distribution of PMI mean values (±SD) in patient groups is presented in Table 5.

Table 5. Distribution of the mean values (±SD) of the Panoramic Mandibular

Index (PMI) in T groups

Groups n Panoramic Mandibular Index (PMI) (mean±SD)

Differences in Panoramic Mandibular Index (PMI)

between patient groups

T1 34 0.29±0.08 T2 65 0.26±0.07 T3 30 0.21±0.06 T1 vs T2 p=0.016 T1 vs T2 p<0.001 T2 vs T3 p=0.009 Total 129 0.26±0.07 T2 + T3 95 0.24±0.07

MI differences between age groups were calculated by applying ANOVA (F=3.26; df=4; p=0.014). PMI differences calculated between age groups by using ANOVA (F=4.56; df=4; p=0.002). The data are presented in Table 6.

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Table 6. The distribution of 95% CI and mean values (±SD) of the Mental Index

(MI) and the Panoramic Mandibular Index (PMI) in age groups

Age groups n Mental Index (MI) (mean±SD) and 95% CI Differences in Mental Index (MI) between age groups Panoramic Mandibular Index (PMI) (mean±SD) and 95% CI Differences in Panoramic Mandibular

Index (PMI) between age groups 1 (<55 years) 17 3.98±0.93 [3.50–4.45] 0.32±0.06; [0.28–0.34] 2 (55–59 years) 23 [2.87–3.51] 3.19±0.74 [0.22–0.27] 0.25±0.06 3 (60–64 years) 49 [3.06–3.54] 3.30±0.84 [0.24–0.28] 0.26±0.07 4 (65–69 years) 29 3.04±1.14 [2.61–3.48] 0.23±0.07 [0.20–0.26] 5 (≥70) 11 [2.27–3.66] 2.97±1.04 1 vs 2 p=0.009; 1 vs 3 p=0.010; 1 vs 4 p=0.001; 1 vs 5 p=0.006; 2 vs 3 p=0.639; 2 vs 4 p=0.577; 2 vs 5 p=0.518; 3 vs 4 p=0.242; 3 vs 5 p=0.288; 4 vs 5 p=0. 818 [0.17–0.29] 0.23±0.09 1 vs 2 p=0.002; 1 vs 3 p=0.005; 1 vs 4 p=0.001; 1 vs 5 p =0.002; 2 vs 3 p=0.467; 2 vs 4 p=0.406; 2 vs 5 p=0.544; 3 vs 4 p=0.077; 3 vs 5 p=0.224; 4 vs 5 p=0.977 Total 129 [3.12–3.45] 3.28±0.96 [0.24–0.27] 0.26±0.07

Data on the statistical dependence of MI and PMI on calcaneal T score, calcaneal bone mineral density and mineral mass, the number of teeth, PI according to Russell, the duration of the post–menopausal period, and age in the general population of the subjects are presented in Table 7.

Table 7. Dependence of the Mental Index (MI) and the Panoramic Mandibular

Index (PMI) on calcaneal bone mineral density, the number of teeth, PI according to Russell, the duration of the post–menopausal period, and age in the general

population of the subjects

Statistical dependence with the Mental Index

(MI)

Statistical dependence with the Panoramic Mandibular Index (PMI) Characteristic n

Measurement values,

mean±SD correlation

coefficient p correlation coefficient p Calcaneal T score 129 –1.62±1.12 0.368 <0.001 0.409 <0.001 Calcaneal BMD (g/cm2) 129 0.38±0.07 0.356 <0.001 0.397 <0.001 Calcaneal BMM (g) 129 1.95±0.41 0.336 <0.001 0.351 <0.001 Number of teeth 129 21.53±5.95 0.339 <0.001 0.297 <0.001 PI according to Russell 129 4.31±1.98 –0.075 > 0.05 0.068 >0.05 Duration of post– menopausal period 129 12.53±6.49 –0.364 <0.001 –0.404 <0.001 Age (years) 129 62.49±6.12 –0.235 <0.01 –0.275 <0.001

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Data on the statistical dependence of MI and PMI on calcaneal bone mineral density, the number of teeth, PI according to Russell, the duration of the post–menopausal period, and age in the groups of subjects are presented in Table 8.

Table 8. Relationship of the Mental Index (MI) and the Panoramic Mandibular

Index (PMI) with calcaneal bone mineral density and mass, the number of teeth, PI according to Russell, the duration of the post–menopausal period, and age in T groups

Gr. n Measurement values, mean±SD

Dependence on the

Mental Index (MI) Dependence on the Panoramic Mandibular Index (PMI) T1 34 –0.13±0.55 r=0.166; p=0.347 r=0.137; p=0.439 T2 65 –1.77±0.43 r=0.137; p=0.277 r=0.168; p=0.179 Calcaneal T score T3 30 –2.96±0.48 r=0.05; p=0.812 r=0.035; p=0.853 T1 34 0.47±0.04 r=0.158; p=0.372 r=0.131; p=0.459 T2 65 0.37±0.03 r=0.151; p=0.228 r=0.186; p= 0.139 Calcaneal BMD (g/cm2) T3 30 0.29±0.03 r=0.003; p=0.988 r=–0.012; p=0.949 T1 34 2.46±0.25 r=0.133; p=0.454 r=0.109; p=0.539 T2 65 1.89±0.191 r=0.169; p=0.177 r=0.139; p=0.269 Calcaneal BMM (g) T3 30 1.48±0.23 r=–0.103; p=0.589 r=–0.207; p=0.271 T1 34 59.38±6.37 r=0.101; p=0.571 r=0.132; p=0.457 T2 65 62.31±5.00 r=–0.259; p=0.038* r=–0.366; p=0.003** Age (years) T3 30 66.42±6.05 r=–0.062; p=0.745 r=–0.07; p=0.701 T1 34 8.35±5.40 r=0.00 p=0.997 r=–0.005; p=0.977 T2 65 12.75±5.33 r=–0.345; p=0.005** r=–0.431; p=0.000*** Duration of post– menopausal period T3 30 16.80±7.12 r=–0.391; p=0.036* r=–0.331; p=0.079 T1 34 21.12±5.83 r=0.397; p=0.020* r=0.296; p=0.089 T2 65 22.54±6.06 r=0.339; p=0.006** r=0.333; p=0.007** Number of teeth T3 30 19.83±5.58 r=0.238; p=0.215 r=0.254; p=0.184 T1 34 4.54±1.93 r=–0.143; p=0.418 r=–0.054; p=0.760 T2 65 4.18±1.99 r=–0.03; p=0.794 r=–0.072; p=0.569 PI according to Russell T3 30 4.33±2.05 r=–0.179; p=0.342 r=–0.185; p=0.329 Note. * the correlation was significant at <0.05 level; ** the correlation was significant at <0.01 level; *** the correlation was significant at <0.001 level.

Interpretation of the ROC curves served as a basis for prognosticating bone mineral density reduction (osteopenia + osteoporosis) according to MI and PMI. In the logistic regression, MI area under the ROC curve was

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0.671 (95% CI – from 0.562 to 0.780). If the diagnostic threshold value was 3.14, the sensitivity of the study was 73.5%, and specificity – 72.6%.

PMI area under the ROC curve was 0.701 (95% CI – from 0.601 to 0.800). If the diagnostic threshold value was 0.24, the sensitivity of the study was 73%, and specificity – 53.7%.

According to the determined MI diagnostic threshold value, the Index can be differentiated into MI1 <3.14 mm and MI2 ≥3.14 mm. Then MI1 n=65 (50.4%); MI2 n=64 (49.6%). The distribution of the mean values (±SD) of MI 1 and MI 2 in patient groups is presented in Table 9.

Table 9. Distribution of the mean values (±SD) of MI 1 and MI 2 in T groups

MI 1 (<3.14 mm) MI 2 (≥ 3.14mm) T score

groups n mean (±SN) n mean (±SN) p*

T1 10 2.53±0.34 24 4.17±0.71 p<0.001 T2 33 2.60±0.36 32 4.10±0.69 p<0.001

T3 22 2.35±0.44 8 3.66±0.31 p<0.001

Note. Mann–Whitney U test was used in the analysis.

We determined the Mandibular Cortical Index (MCI) according to Klemetti (1994), and differentiated changes in the morphology of the cortical bone of the mandibular base into three morphological groups: C1 – the endosteal margin of the cortex even sharp on both sides, С2 – the endosteal margin showing semilunar defects or seeming to form endosteal cortical residues on one or both sides; C3 – the cortical layer formed heavy endosteal cortical residues and was clearly porous. We also calculated value differences in MCI groups according to ANOVA: age (F=5.36; df=2; p=0.006); duration of the post–menopausal period (F=10.40; df=2; p<0.001); the number of teeth (F=2.68; df=2; p=0.072); calcaneal bone mineral density (F=5.64; df=2; p<0.01); and calcaneal bone mineral mass (F=5.098; df=2; p=0.007).

Mean values (±SD) of calcaneal BMD, MI, PMI, age, and the duration of the post–menopausal period (±SD) in MCI groups are presented in Table 10.

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Table 10. Mean values (±SD) of calcaneal bone mineral density and mandibular

indices, mean age, number of teeth and mean duration of the post–menopausal period in MCI groups

C 1 C 2 C 3 Total n=17 n=64 n=44 n=128 Differences between groups Calcaneal BMD (mean±SD) (g/cm2) 0.41±0.06 0.39±0.08 0.35±0.07 0.38±0.07 C1 vs C2 p=0.193; C1 vs C3 p<0.01; C2 vs C3 p=0.011. Calcaneal BMM (mean±SD) (g) 2.12±0.29 2.0±0.44 1.80±0.36 1.95±0.41 C1 vs C2 p=0.301; C1 vs C3 p<0.01; C2 vs C3 p=0.010. MI (mean±SD) 4.26±0.99 3.50±0.86 2.62±0.53 3.29±0.95 C1 vs C2 p<0.001; C1 vs C3 p<0.001; C2 vs C3 p<0.001. PMI (mean±SD) 0.33±0.07 0.27±0.07 0.20±0.04 0.26±0.07 C1 vs C2 p=0.01; C1 vs C3 p<0.001; C2 vs C3 p<0.001. Age (mean±SD) (years) 58.13±6.64 62.83±6.00 63.33±5.11 62.38±5.99 C1 vs C2 p<0.01; C1 vs C3 p<0.01; C2 vs C3 p>0.05. Duration of post– menopausal period (mean±SD) 7.18±5.21 12.13±6.28 14.42±6.39 12.42±6.39 C1 vs C2 p<0.01; C1 vs C3 p<0.001; C2 vs C3 p<0.05. Number of teeth (mean±SD) 24.41±5.37 21.62±5.96 20.59±5.62 21.64±5.85 C1 vs C2 p=0.078; C1 vs C3 p=0.022; C2 vs C3 p=0.357. MCI was statistically significantly related to calcaneal bone mineral density (r=–0.286; p<0.001); calcaneal bone mineral mass (r=–0.270; p<0.01); MI (r=–0.580; p<0.001); PMI (r=–0.567; p<0.001); duration of the post–menopausal period (r=0.369; p<0.001); and the number of teeth (r=–0.190; p<0.05);

Differences in the MI in MCI groups according to ANOVA were F=31.80; df=2; p<0.001. [C1 vs C2 p<0.001; C1 vs C3 p<0.001; C2 vs C3 p<0.001].

PMI differences in MCI groups according to ANOVA F=30.02; df=2; p<0.001. [C1 vs C2 p=0.01; C1 vs C3 p<0.001; C2 vs C3 p<0.001].

The distribution of MI and PMI in MCI groups according to the diagnostic threshold values is presented in Table 11.

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Table 11. The distribution of the Mental Index (MI) and the Panoramic

Mandibular Index (PMI) in MCI groups according to the diagnostic threshold values

MI 1 (<3.14 mm)

(n) MI 2 (≥ 3.14 mm)(n) PMI 1 (<0.24) (n) PMI 2 (≥ 0.24) (n) C1 2 (3.13%) 15 (23.44%)* 2 (3.23%) 15 (22.73%)* C2 25 (39.06%)*** 42 (65.63%)*** 23 (37.10%)*** 44 (66.67%)*** C3 37 (57.81%) 7 (10.94%)** 37 (59.68%) 7 (10.61%)**

Note. *C1 vs C2; **C1 vs C3; ***C2 vs C3. The proportion difference at <0.05 level; ** the proportion difference at <0.01 level; *** the proportion difference at <0.001 level.

The distribution of mean (±SD) calcaneal T score and bone mineral density in the MCI groups is shown in Table 12.

Table 12. The distribution of mean (±SD) calcaneal T score and bone mineral

density in the Mandibular Cortical Index (MCI) groups

C1 С2 С3

Characteristic

n mean (±SD) n mean (±SD) n mean (±SD) p* T score 8 –0.28±0.40 20 0.01±0.57 6 –0.40±0.55 C1 vs C2 p<0.05 C1 vs C3 p<0.05 C2 vs C3 p<0.05 T1 Calcaneal BMD 8 0.47±0.03 20 0.49±0.04 6 0.46±0.04 C1 vs C2 p>0.05 C1 vs C3 p>0.05 C2 vs C3 p>0.05 T score 8 –1.72±0.39 33 –1.75±0.40 24 –1.81±0.50 C1 vs C2 p>0.05 C1 vs C3 p>0.05 C2 vs C3 p>0.05 T2 Calcaneal BMD 8 0.37±0.03 33 0.37±0.03 24 0.36±0.03 C1 vs C2 p<0.05 C1 vs C3 p<0.05 C2 vs C3 p<0.05 T score 1 – 2.50 14 –2.91±0.42 14 –3.03±0.56 C2 vs C3 p<0.05 T3 Calcaneal BMD 1 0.32 14 0.29±0.03 14 0.29±0.04 C2 vs C3 p<0.05

Note. Mann–Whitney U test.

There was no statistically significant difference in the mean values of the morphometric measurements between the right and left sides of the mandible (p>0.05), and thus the Mandibular Resorption Index (MRI) was calculated using mean values of AB and MB measurements. The mean value (±SD) of the MRI was 2.32±0.25; the lowest value was 1.77, and the highest – 2.97. MRI statistically significantly correlated with the number of teeth (r=0.231; p=0.009), and was inversely proportional to PI according to Russell (r=–0.211; p=0.017). No statistically significant relationship was found between MRI and other analyzed parameters.

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We evaluated optical density of the cortical and trabecular bone at the mental foramen on panoramic radiography images of the mandibles. We calculated coefficients of variation (CV) for optical density measurements preformed by the main researcher (I) and two independent researchers (II and III). Trabecular bone: researcher I – 12.72%; researcher II – 19.99%; and researcher III – 15.86%; cortical bone: researcher I – 14.10%; researcher II – 16.21%; and researcher III – 13.56%.

The differences in the optical density of the cortical bone between the groups of subjects were determined by applying ANOVA (F=0.125; df=2; p=0.883); the differences in the optical density of the trabecular bone between the groups of subjects according to ANOVA were F=0.836; df=2; p=0.436. The findings of the densitometry examination are presented in Table 13.

Table 13. Results of mandibular densitometry

T groups Group T1 Group T2 Group T3 Total

n n=34 n=65 n=30 n=129 OD MCB, mean±SD 0.66±0.08 0.66±0.09 0.65±0.12 0.66±0.09 Lower margin 0.63 0.64 0.60 0.64 Upper margin 95% CI of the mean values of the OD MCB 0.69 0.68 0.69 0.67 Differences between groups (p) T1 vs T2 p=0.989; T1 vs T3 p=0.672; T2 vs T3 p=0.641; OD MTB, mean±SD 0.67±0.08 0.67±0.08 0.64±0.10 0.66±0.08 Lower margin 0.64 0.65 0.60 0.65 Upper margin 95% CI of the mean values of the OD MTB 0.69 0.69 0.69 0.68 Differences between groups (p) T1 vs T2 p=0.991; T1 vs T3 p=0.287; T2 vs T3 p=0.223;

We determined the relationship between mean (±SD) optical density of the cortical and trabecular bone in calcaneal bone mineral density (T score) and MCI groups (Table 14).

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Table 14. Distribution of the data on the optical density of cortical and trabecular

bone in the calcaneal bone mineral density (T score) and the Mandibular Cortical Index (C) groups Characteristic Group n Optical density of the cortical bone (mean±SD) Optical density of the trabecular bone (mean±SD) Difference between the optical density values p T1 34 0.66±0.08 0.67±0.08 –0.008 0.184 T2 65 0.66±0.08 0.67±0.07 –0.009 0.214 Calcaneal BMD group T3 30 0.65±0.12 0.64±0.10 0.004 0.674 C1 17 0.66±0.08 0.65±0.07 0.004 0.639 С2 67 0.65±0.10 0.66±0.09 –0.013 0.067 MCI group C3 44 0.67±0.08 0.67±0.07 0.001 0.923

We found no statistical dependence of the cortical and trabecular OD of the mandible on the duration of the post–menopausal period, calcaneal T score, calcaneal bone mineral density, the number of teeth, MI, or MCI.

3.4. Linear morphometric measurements of the mandible (in vitro)

We performed in vitro linear morphometric measurements of the mandible on the vestibular surface, on panoramic radiography images, on CT reconstructions, and in mandibular section fragments. The analysis presents data on the mental foramen fragment (B) adjusted for the magnification coefficient.

The mean distance (±SD) between the upper margin of the alveolar part and the lower margin of the base on the vestibular surface of the mandible on the right and the left side was, accordingly, B1 27.54±4.62 (mm) and B2 27.64±3.81 (mm) (B1 vs B2 p>0.05). The mean distance between the center of the mental foramen and the lower margin of the mandibular base was, respectively, D1 13.61±1.34 (mm) and D2 13.46±1.50 (mm) (D1 vs D2 p>0.05).

We performed vertical linear measurements following Ledgerton’s technique in 28 panoramic radiography images of the mandibles. We measured distances: the distance between the upper margin of the alveolar part of the mandible and the lower margin of the mandibular base (B1, B2), the distance between the center of the mental foramen of the mandible and the lower margin of the mandibular base (D1, D2), cortical width in the mandibular base (E1, and E2) and calculated mean values of the measurements (±SD): B1 30.18±7.44 (mm); B2 29.70±7.37 (mm) (B1

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vs B2 p>0.05); D1 13.11±2.96 (mm); D2 12.72±3.20 (mm) (D1 vs D2 p>0.05); E1 4.32±1.34 (mm); and E2 4.33±1.31 (mm) (E1 vs E2 p>0.05). The following relationships were found between measurements of the vestibular surface and panoramic radiography images: between B1 r=0.636; p<0.001; between B2 r=0.744; p<0.001; between D1 r=0.597; p<0.001; and between D2 r=0.614; p<0.001.

We analyzed and compared findings of the measurements of cortical width in the mandibular base of mandibular CT reconstructions, mandi-bular section fragments, and panoramic radiography images.

Table 15. Statistical dependence on the mean measurement values of cortical

width in the mandibular base of quantitative computed tomograms of the mandible and section fragments (±SD)

Mean values (±SD) of the CT reconstructions measurements (mm)

Mean values (±SD) of the section fragment measurements (mm)

Correlation coefficient and level of significance B1(2) 3.63±0.80 B1(2) 3.63±0.86 r=0.854; p<0.001 B2(2) 3.74±0.85 B2(2) 3.78±0.77 r=0.679; p<0.001 Note. CT B1(2) vs B2(2) p>0.05; section fragments B1(2) vs B2(2) p>0.05.

The tomographically determined mean values (±SD) of cortical width measurements in the mandibular base (B1(2) and B2(2)) were statistically significantly related to the mean values (±SD) of E1 and E2 on panoramic radiography images (respectively, r=0.408; p<0.05; r=0.411; p<0.05).

The results of the panoramic radiography measurements of cortical width in the mandibular base statistically significantly correlated with the results of the measurements of mandibular bone section fragments: the correlation between E1, E2 mean values (±SD) and B1(2), B2(2) mean values (±SD) was, respectively, r=0.558; p<0.01 and r=0.613 p<0.01.

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4. CONCLUSIONS

1. In the group of post–menopausal women, mandibular bone mineral density calculated using the Mental Index (MI), Panoramic Mandibular Index (PMI), and Mandibular Cortical Index (MCI) was statistically significantly related to calcaneal bone mineral density (BMD) (p<0.001). No statistically significant association was found between calcaneal BMD and optical density of the mandible determined on panoramic radiography images.

2. The number of remaining teeth depended on mandibular bone mineral density calculated using MI, PMI (p<0.001), and MCI (p<0.05). Densitometry of the mandible showed a tendency of the number of remaining teeth to be statistically dependent on the optical density of the mandible.

3. Mandibular body height (MRI) was not dependent on mandibular BMD.

4. Panoramic radiomorphometric indices can be used for the evaluation of changes in mandibular bone mineral density. Cortical width in the mandibular base at the mental foramen below 3.14 mm (area – 0.671, sensitivity – 73.5%, specificity – 72.6%) and Panoramic Mandibular Index approaching 0.24 (area – 0.701, sensitivity – 73.0%, specificity – 53.7%) are prognostic indicators of calcaneal BMD reduction.

5. The condition of periodontal tissues was not dependent on mandibular BMD, but due to the inflammatory destruction of periodontal tissues, it was statistically significantly related to the mandibular body height (MRI) (p<0.05).

6. Calcaneal bone mineral density had no effect on the mandibular body height (MRI) or the number of remaining teeth.

7. The subjects’ age and the duration of the post–menopausal period affected the radiomorphometric indices of the mandible (p<0.001), the number of remaining teeth (p<0.01), and calcaneal BMD (p<0.001), but had no influence on the mandibular body height (MRI).

8. In vitro examination confirmed the interrelationship between different morphometric examination techniques of the mandible and helped to evaluate the accuracy of these techniques in evaluating mandibular cortical bone. Due to its advantages, panoramic radiography is suitable and can be used in panoramic radiomorphometric studies of the cortical bone in the mandibular base.

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5. CLINICAL RECOMMENDATIONS

1. In clinical odontological practice, when analyzing panoramic radiography images in post–menopausal patients, we recommend noting, evaluating, and measuring the cortical width of the mandibular base at the mental foramen. If the value of the measurement is below 3.14 mm, bone mineral density reduction in the mandible should be diagnosed, and further evaluation of bone mineral density – in this case, calcaneal DXL – should be suggested along with the evaluation of the general osteoporotic changes in the skeleton.

2. Due to its convenient clinical practical determination, the Mental Index (MI) should be chosen as a diagnostic indicator of osteoporosis in the mandible. Statistical dependence of the Mental Index (MI) and the Panoramic Mandibular Index (PMI) is very similar, yet methodological inaccuracies may occur in determining the Panoramic Mandibular Index, and thus when calculating PMI, measurements of this index should be performed from the center of the mental foramen to the lower margin of the mandibular base (according to Taguchi, 1995), the location of the mental foramen should be specified several times, or the examination of that side of the mandible should be forgone altogether.

3. The Mandibular Cortical Index (MCI) should be used as a diagnostic criterion for osteoporosis, but its clinical data should be complemented with other indices and examination techniques.

4. The number of the teeth should be evaluated as one of clinical signs of mandibular bone mineral density.

5. We recommend restoration of the mechanical occlusal load and masticatory function for post–menopausal patients in order to preserve mandibular bone mass, cortical width in the mandibular bone, the number of teeth, and physiological structures of the joint, as well as to stop alveolar bone resorption.

6. We recommend associating the mandibular body height seen on panoramic radiography images with inflammatory destruction of perio-dontal tissues.

7. Because of the accuracy of DXL Calscan examination, no required evaluation of additional foci of calcification, convenient use of the apparatus, functional and metabolic activity of the calcaneus, low incidence of osteoporotic fractures in this bone, especially slight age– related changes in the bone tissue, low amounts of surrounding soft tissue, and the dependence of calcaneal BMD on the subjects’ age and the

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duration of the post–menopausal period, we suggest that bone mineral density in post–menopausal women should be examined in the calcaneus by applying the DXL technique, and the results of the examination should be preserved for the monitoring of the course of changes in bone mineral density.

6. LIST OF PUBLICATIONS

1. Jagelavičienė E, Kubilius R, Krasauskienė A. The relationship between panoramic radiomorphometric indices of mandible and calcaneus bone mineral density. (Accepted to „Medicina“ (Reference issued on 2009.06.03)).

2. Jagelavičienė E, Kubilius R, Krasauskienė A, Butkuvienė GE. Kulnakaulio ir apatinio žandikaulio kaulų mineralų tankio priklausomybė ir ryšys su dantų skaičiumi burnos ertmėje pomenopauzinio amžiaus moterims. Lietuvos endokrinologija 2008;16:38-45. (Interdependence between bone mineral density in the calcaneus and the mandible, and its relationship with the number of teeth in post–menopausal women) (in Lithuanian)

3. Jagelavičienė E, Kubilius R, Gedrimas VL, Vaitkus A, Monasty-reckienė E, Vitkus A, Barsukov N. Analysis of the human mandible cor-tical layer using different morphometric technics. Tavricheskiy medico– biologicheskiy vestnik 2007;10(3)143-8.

4. Jagelavičienė E, Kubilius R. Ryšys tarp bendrosios skeleto osteo-porozės ir priedančio audinių ligų. Medicina 2006;42(8):613-8. (The rela-tionship between general ostoporosis of the skeleton and periodontal disea-ses (in Lithuanian)

5. Jagelavičienė E, Kubilius R, Krasauskienė A, Butkuvienė GE, Ged-rimas VL, Nedzelskienė I. The relationship of hucklebone T score with the thickness of the cortical layer in the mandible base and the tooth mobility in postmenopausal women patients. Baltic endocrinology 2006;2(1):14-8.

Theses:

1. Jagelavičienė E, Kubilius R, Gedrimas VL, Vaitkus A, Monasty-reckienė E. Morphometric analyses of the human mandible at the mental foramen. The 2nd Baltic Scientific Conference of Dentistry, Riga (Latvia). Baltic Dental and Maxillofacial Journal 2007;1(4):30.

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2. Jagelavičienė E, Kubilius R, Gedrimas VL, Vaitkus A, Monasty-reckienė E. Morphometric characteristic of the human mandible and mandibular cortical layer. Oulu– Kaunas: 2nd international congress of odontology and maxillofacial surgery, Kaunas (Lithuania). Stomatologija: Baltic Dental Maxillofacial Journal 2006;8(1):28-9.

SUMMARY IN LITHUANIAN

Darbo tikslas yra panoraminės radiografijos metodu ištirti apatinio žandikaulio kaulų mineralų tankį, jo įtaką išlikusių dantų skaičiui, bendram apatinio žandikaulio kūno aukščiui ir nustatyti ryšį tarp apatinio žandikaulio panoraminių radiomorfometrinių indeksų ir kulnakaulio kaulų mineralų tankio pomenopauzinio amžiaus moterims.

Uždaviniai: 1) ištirti ryšį tarp apatinio žandikaulio panoraminių ra-diomorfometrinių indeksų, rodančių apatinio žandikaulio kaulų mineralų tankį, apatinio žandikaulio panoraminėse radiogramose išmatuoto optinio tankio ir kulnakaulio kaulų mineralų tankio; 2) pagal apatinio žandikaulio panoraminius radiomorfometrinius indeksus ir densitometrinį tyrimą apskaičiuoti apatinio žandikaulio kaulų mineralų tankį, nustatyti jo ryšį su išlikusių dantų skaičiumi, bendru apatinio žandikaulio kūno aukščiu, įvertinti radiomorfometrinių indeksų diagnostinį efektyvumą; 3) išana-lizuoti apatinio žandikaulio kaulų mineralų tankio pokyčių įtaką priedančio audiniams; 4) įvertinti kulnakaulio kaulų mineralų tankio (bendro skeleto) sąsajas su išlikusių dantų skaičiumi ir bendru apatinio žandikaulio kūno aukščiu; 5) nustatyti amžiaus ir pomenopauzinio periodo sąsają tarp kulna-kaulio ir apatinio žandikulna-kaulio kaulų mineralų tankio, bendro apatinio žandikaulio kūno aukščio, išlikusių dantų skaičiaus; 6) atlikti apatinių žandikaulių tankiosios kaulinės medžiagos morfometrinę analizę in vitro ir įvertinti panoraminio radiografinio tyrimo patikimumą tiriant pamato tan-kiąją kaulinę medžiagą.

Tiriamųjų kontingentą sudarė pomenopauzinio amžiaus moterys nuo 50 iki 77 metų amžiaus, kurios lankėsi KMU Dantų ir burnos ligų klinikoje dėl priedančio audinių patologijos.

Tyrimo metodiką sudarė tiriamų asmenų klinikinis burnos ištyrimas, panoraminis radiografinis tyrimas ir morfometrinės vaizdų analizės atlikimas, kulnakaulio kaulų mineralų tankio tyrimas. Matavimų tikslumui nustatyti buvo atliktas apatinių žandikaulių prieanginio paviršiaus, pano-raminio radiografinio, CT rekonstruotų fragmentų ir žandikaulių pjūvių

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fragmentų morfometriniai tyrimai in vitro bei gautų duomenų statistinės duomenų analizė.

Remiantis tyrimų duomenimis, padarytos išvados: 1) pomenopauzinio amžiaus moterų apatinio žandikaulio kaulų mineralų tankis, nustatytas pagal smakro angos (MI), panoraminį (PMI) ir apatinio žandikaulio pa-mato tankiosios kaulinės medžiagos indeksus (MCI), statistiškai reikš-mingai susijęs su kulnakaulio kaulų mineralų tankiu (p<0,001). Statistiškai reikšminga priklausomybė tarp kulnakaulio kaulų mineralų tankio ir apatinio žandikaulio optinio tankio panoraminėse radiogramose nenusta-tyta; 2) dantų skaičius priklauso nuo apatinio žandikaulio kaulų mineralų tankio, apskaičiuoto pagal smakro angos, panoraminį (p<0,001) ir apatinio žandikaulio pamato tankiosios kaulinės medžiagos (p<0,05) indeksus. Apatinio žandikaulio densitometrinė analizė rodo tendenciją į dantų skaičiaus statistinę priklausomybę nuo apatinio žandikaulio optinio tankio; 3) bendras apatinio žandikaulio kūno aukštis nepriklauso nuo apatinio žandikaulio kaulų mineralų tankio; 4) panoraminiai radiomorfometriniai indeksai tinka kaulų mineralų tankio pokyčiams įvertinti. Išmatuotas mažesnis negu 3,14 mm apatinio žandikaulio pamato tankiosios kaulinės medžiagos storis ties smakro anga (plotas – 0,671, jautrumas – 73,5%, specifiškumas – 72,6%) bei apskaičiuota panoraminio indekso reikšmė, artima 0,24 (plotas –0,701, jautrumas – 73,0%, specifiškumas – 53,7%), yra prognostiniai kulnakaulio kaulų mineralų tankio sumažėjimo rodikliai; 5) apatinio žandikaulio kaulų mineralų tankis nesusijęs su priedančio audinių būkle, bet nuo jos priklauso bendro apatinio žandikaulio kūno aukštis (p<0,05); 6) kulnakaulio kaulų mineralų tankis nelemia bendro apatinio žandikaulio kūno aukščio pokyčio ir burnoje išlikusio dantų skai-čiaus; 7) tiriamųjų amžius ir pomenopauzinio periodo trukmė turi įtakos apatinio žandikaulio radiomorfometriniams indeksams (p<0,001), išlikusių dantų skaičiui (p<0,01) ir kulnakaulio kaulų mineralų tankiui (p<0,001), bet neturi įtakos bendram apatinio žandikaulio kūno aukščiui; 8) tyrimas in vitro patvirtino skirtingų apatinio žandikaulio morfometrinių tyrimo meto-dų tarpusavio priklausomybę, padėjo įvertinti jų tikslumą analizuojant apatinio žandikaulio tankiąją kaulinę medžiagą. Panoraminė radiografija yra tinkama naudoti panoraminiams radiomorfometriniams apatinio žan-dikaulio pamato tankiosios kaulinės medžiagos tyrimams.

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BRIEF INFORMATION ABOUT THE AUTHOR

OF THE DOCTORAL DISSERTATION

Eglė Jagelavičienė Birth date: 1968.06.09

1987–1992 – studies at Faculty of Stomatology, Kaunas Academy of Medicine (presently Faculty of Odontology, Kaunas University of Me-dicine)

1992–1993 – postgraduate studies (Clinical of Stomatology, Kaunas Academy of Medicine)

1994–1995 – postgraduate studies of periodontology (Faculty of Stomatology, Kaunas Academy of Medicine)

1995 – Specialization in Malmö Dental School, Sweden

2006–2010 – doctoral studies at Kaunas University of Medicine Office address: Clinic of Dental and Oral Diseases

Faculty of Odontology

Kaunas University of Medicine Eivenių 2

LT–50009 Kaunas

Lithuania

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