| I. PrefaceLoss of single or more teeth in the maxillary posterior is a common case as well as a difficulty in dental implantation and restoration. In case of tooth loss in this area and alveolar ridge abstraction, since the anatomical position is adjacent to maxillary sinus and due to pneumatization of the maxillary sinus, the height of the alveolar bone in this area is usually less than10mm, which is not sufficient bone for implantation in an ordinary way, making the operation complex and reducing its success rate. Other reasons that may cause insufficient bone in this area include: serious alveolar ridge resorption before extractations due to periodontitis, injury or surgery; alveolar bone resorption due to hormone meTableolism, etc. In order to solve this problem, the maxillary posterior may be increased by lifting the maxillary sinus and through bone augmentation, with the purpose-of realizing the dental implantation and restoration This technique was introduced by Tatum in1975. The maxillary sinus plasty technique was firstly reported by Boyne and Jame, and then, it has been improved by many scholars to finally form two major operation methods: (1) lateral windows technique; and (2) osteotome sinus floor elevation technique (or transalveolar technique). This technique has been proved to be effective in clinic, and the success rate of implantation is increased accordingly.As there are many variations in anatomical structures of the maxillary sinus and nearby area, it brings difficulties to the design of the way and method of the operation for bone augmentation in the maxillary posterior, as a result, to understand the anatomical structures inside and nearby the maxillary sinus becomes critical to decide success or failure of sinus lift. In recent years, Cone-beam Computerized Tomography (CBCT) is proved to have more advantages than other imaging methods in its resolution, accuracy, effective dose and multi-plane image reconstruction, and it brings conveniences to research and analysis on anatomical structures of the maxillary sinus through imaging in clinic. So far, seldom scholars from home and aboard have made research reports on maxillary sinus anatomical imaging, thus the relevant data are not sufficient enough to be a reference for esTablelishing a standard in the operation for bone augmentation in the maxillary sinus. The study aims to esTablelish a sample questionnaire information bank for Han people as well as a CBCT daTablease of their maxillary sinus, and to measure relevant data of the key anatomical structures of their maxillary sinus and nearby area, with the purpose of bringing references to making treatment plans for dental implantation and repair involving maxillary sinus, and esTablelishing methods and standards of measurement in order to track and research the anatomical variations in the maxillary sinus on a long-term basis. Ⅱ. ObjectivesThe study aims to observe the anatomical of the maxillary sinus of Han people through CBCT;1. The incidence rate of bone septa in maxillary sinus, and their position and height; 2. The average, minimum and maximum value of the mesial-distal distance of the inwall of maxillary sinus, the difference between different sex, left and right side, and the relationship with the time of tooth loss:3. The average, minimum and maximum value of the width of buccal-palatal side of maxillary sinus, the difference between different sex, left and right side, and the relationship with the time of tooth loss;4. The average, minimum and maximum value of lateral wall of maxillary sinus, and the difference between different sex, and left and right side. III. Material and methods1. Collection of clinical data:To establelish the questionnaire library of the patients receiving CBCT in head due to orthodontic or dental implantation accepted by Special Clinic Center of Guangdong Provincial Stomatological Hospital.2. Testing instruments:QR-DVT9000NEWTOM Special CT for maxillofacial.Special built-in software QR-NNT Version3.00(English version).3. Measuring methods:(1) Calibration:after taking CBCT picture, a folder with the name of the examinee will generate automatically, then open the file Dicom under Volumetric Data and execute initial reconstruction, the rectangular box (AP,LL) will appear; allow the horizontal baseline of the rectangular box under sagittal section to parallel to the connection line between anterior nasal spine (ANS) and posterior nasal spine (PNS), while the measuring range of the rectangular box should cover the maxillary. In ISO column, select layer thickness0.5mm, adjust contrast and gray scale, then go to Study mode for reconstruction, and finally start measuring the items to be researched after selecting the corresponding base point and section. (2)The maxillary sinus septaIn column Freecut, click to open the axial plane and move the observing column, the position of septa in maxillary sinus at both sides will be found; cut the sagittal section of the position of the septa using New freecut command in the software, then set the bottom wall of the maxillary sinus as the base point to measure the height at the highest position of the the septa and record the position of the the septa at the bottom wall of maxillary sinus corresponding to natural tooth root.(3) Mesial-distal distance of inwall of maxillary sinusIn MPR column under Study mode, the horizontal baseline in the axis plane column should pass through the Zygomaticalveolar line (ZAC line), and the central baseline should pass through the central line; after adjustment, confirm and record the image No. Ax(n) of the low point of cortical bone at the nasal cavity side of hard palate in coronal section column, and cut the axis image from10mm above it in Freecut column, then measure the mesial-distal distance of the inwall of maxillary sinus using the software in toolbar.(4) Thickness of front lateral wall of maxillary sinusThe same as measuring the mesial-distal distance of inwall of maxillary sinus(5) Width of buccal-palatal side of maxillary sinusIn MPR column under Study mode, adjust the horizontal base in axis plane column to allow it to pass through the ZAC line, and allow the central baseline to pass through the central line, then go to Freecut column and with ZAC line as the baseline, cut a coronal section using New freecut command; in this section, with the horizontal plane of the hard palate as the baseline, measure the width of buccal-palatal side of maxillary sinus according to the distance between the inwall and lateral wall of maxillary sinus at the same side.1. Statistics method Measure the CBCT index of all subjects of study for three times with an interval more than2d. All measurements should be completed by the same person on the same PC. Carry out statistics processing on the measurement data using SPSS13.0software package. The measurement data are subject to normal distribution and shown as (X±S); in case of abnormal distribution, if there is a median value in centralization, the dispersion is shown in percentage. To inspect two independent samples t and conduct Paired-Sample T Test, the single factor analysis of variance of repeted measure and to make group comparison with χ2inspection, if P<0.05, then the statistics make sense.IV. ResultsA total of243questionnaires and the Dicom raw data are collected in the clinic test. Excluding22failure data, a total of221valid data are included in the research. The patients include130males and91females,221in total, among which, the youngest is18years old, and the oldest is83years old. The average age is49.51. Among the221patients,58patients have no tooth loss in posterior teeth area of the maxilla, and84have partial tooth loss in posterior teeth area of the maxilla at single side,62have partial tooth loss in posterior teeth area of the maxilla at both sides, and17have no tooth in maxilla.1.The septa in maxillary sinus(1) Incidence rate of sinus septaAmong the CBCT data of221patients,32are suffered from the septa in maxillary sinus. Among442maxillary sinuses of the221patients,51septas are found in44maxillary sinuses, among which35maxillary sinuses have one septa,8have two septas, and1have three septas. The incidence rate of the septa in maxillary sinus is9.50%(42/442) taking number of maxillary sinuses as the subject, or15.38%(34/221) taking number of patients as the subject. (2) Position of the sinus septaThe study takes maxillary sinus as the subject. To divide the maxillary sinus into three parts, that area between the mesial root of the first molar and the front wall of maxillary sinus is the front part, the area between the distal root of the second molar and the back wall of maxillary sinus is the back part, and the area between the mesial root of the first molar and the distal root of the second molar is the middle part. The incidence of the septa varies in different part of the maxillary sinus. The incident in the front part is:25.49%(13/51), the middle part is:66.67%(34/51), and the back part is:7.84%(4/51).(3) Height of the sinus septaAmong51septas, the minimum value is2.9mm, maximum value is14.2mm, and average value is6.50±2.83mm. The average value of septa of left side is6.58±2.54mm, and right side is6.48±2.61mm.The result of the Independent-Sample T Test to the height of sinus septa at left and right side shows that P>0.05, which means there is no evident difference in the height of sinus septa at left and right side.2. Mesial-distal distance of inwall of maxillary sinusAmong442maxillary sinuses, the minimum value of the mesial-distal distance of inwall of maxillary sinus at left side is13.4mm, the maximum value is43.0mm, the average value is33.20±4.68mm, and the median value is34.1mm; the minimum value of the mesial-distal distance of inwall of maxillary sinus at right side is6.1mm, the maximum value is43.7mm, the average value is33.51±4.88mm, and the median value is34.2mm. The result of the Paired-Sample T Test to the maxillary sinus at left and right side shows that P>0.05, which means there is no evident difference in the mesial-distal distance of inwall of maxillary sinus at left and right side. The result of the single factor analysis of variance of repeted measure between different sex shows that P>0.05, which means there is no evident difference in mesial-distal distance of inwall of maxillary sinus between male and female. The influence of the time of tooth loss on the mesial-distal distance of inwall of maxillary sinus is determined through the single factor analysis of variance of repeted measure and comparison between different groups, and both results show that P>0.05, which means there is no relationship between time of tooth loss and mesial-distal distance of inwall of maxillary sinus.3. Width of buccal-palatal side of maxillary sinusAmong442maxillary sinuses, the minimum value of the width of the buccal-palatal side of the221maxillary sinuses at left side is7.3mm, the maximum value is27.0mm, the average value is16.53±3.61mm, and the median value is16.5mm; the minimum value of the width of the buccal-palatal side of the221maxillary sinuses at right side is7.55mm. the maximum value is33.3mm, the average value is16.66±3.61mm, and the median value is16.5mm. The result of the Paired-Sample T Test to the maxillary sinuses at left and right side shows that P>0.05, which means there is no evident difference in the width of the buccal-palatal side of the maxillary sinuses at left and right side. Both results of the single factor analysis of variance of repeted measure to the width of the buccal-palatal side of the maxillary sinuses between difference sex and at both sides show that P>0.05, which means there is no evident difference in the width of the buccal-palatal side of the maxillary sinuses between different sex. The influence of the time of tooth loss on the width of the buccal-palatal side of the maxillary sinuses is determined through the single factor analysis of variance of repeted measure and comparison between different groups, and both results show that P>0.05, which means there is no relationship between time of tooth loss and width of the buccal-palatal side of the maxillary sinuses.4. Thickness of front lateral wall of maxillary sinus Among442maxillary sinuses, the minimum value of the thickness of front lateral wall of the221maxillary sinuses at left side is0.6mm, the maximum value is5.9mm, the average value is1.58±0.57mm, and the median value is1.4mm; the minimum value of the thickness of front lateral wall of the221maxillary sinuses at right side is0.6mm, the maximum value is5.3mm, the average value is1.50±0.51mm, and the median value is1.5mm. The result of the Paired-Sample T Test to the maxillary sinuses at left and right side shows that P>0.05, which means there is no evident difference in the thickness of front lateral wall of the maxillary sinuses at left and right side. Both results of the single factor analysis of variance of repeted measure to the thickness of front lateral wall of the maxillary sinuses between difference sex and at both sides show that P<0.05, which means there is difference in the thickness of front lateral wall of the maxillary sinuses between different sex.V. ConclusionCBCT can be effectively applied in diagnosis before operation of dental implantation in posterior teeth area of the maxilla. Through analysis to the CBCT data of the subject of the test, we have made the following conclusions:1. The incidence rate of the septa in maxillary sinus area of Han people is9.50%(taking number of maxillary sinuses as the subject), or15.38%(taking number of patients as the subject), which is lower than other race. The septas are usually found at the center of the maxillary sinus between the mesiobuccal root of the first molar and the distobuccal root of the second molar, with an average height of6.50±2.83mm.2. The mesial-distal distance of inwall of maxillary sinus of Han people is:at left side, the extreme values are13.4mm and43.0mm, and the average value is34.1mm; at right side, the extreme values are6.1mm and43.7mm, and the average value is34.2mm. In statistics, there is no evident difference between maxillary sinuses at left and right side, or male and female.3. The width of the buccal-palatal side of the maxillary sinus of Han people is:at left side, the extreme values are7.3mm and27.0mm, and the average value is16.5mm; at right side, the extreme values are7.5mm and33.3mm, and the average value is16.5mm. In statistics, there is no evident difference between maxillary sinuses at left and right side, or male and female.4. The thickness of front lateral wall of the maxillary sinus of Han people is:at left side, the extreme values are0.6mm and5.9mm, and the average value is1.4mm; at right side, the extreme values are0.6mm and5.3mm, and the average value is1.5mm. There is no evident difference between maxillary sinuses at left and right side, but difference exits between male and female. The thickness of front lateral wall of maxillary sinus of male is greater than female.5.There is no relationship between time of tooth loss and the mesial-distal distance of inwall of maxillary sinus, or the width of the buccal-palatal side of the maxillary sinus, showing that the length and width of the maxillary sinus are not changeable according to time of tooth loss.6. CBCT can be used for imaging analysis to the anatomy of the maxillary sinus, and can also be used for accurate measurement of special anatomical structures. It features the function of guiding the selection of operation method of implantation of tooth loss and the application of technique for bone augmentation. |
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