| Implantation of tooth is a new technology developed in recent decades, it has many advantages as following: it does not damage adjacent teeth, comfortable, convenient, it has strong function and reliable stability etc. More and more doctors and patients like to accept dental implant. But dental implant is not fit for not all patients, it mainly depends on the conditions of the jaw, including bone width, height and density. With the continuous development of oral implantology, in order to further improve the success rate of implanting, expand the planting indications and reduce the operation risks, more and more details of the jaw conditions should be focus on. Reasonable planting treatment plan, must rely on accurate imaging data support. Since the late 1990 s cone beam CT is applied to oral three-dimensional imaging for the first time, oral CT technology get gradually attention of both oral surgeons and computed tomography(CT) technology researchers. CBCT scanning technology to support more graphic image reconstruction function, which can be able to provide effective help for the establishment of dental implants surgery. Application of CBCT in oral clinical can solve some inherent defects in the conventional two-dimensional perspective imaging distortion of image overlap, and has significant advantages in making 3 D resolution dental implant plan. The purpose of this research is to measure and analyze the alveolar bone height, width and density in edentulous areas by cone beam CT, and evaluate the alveolar bone change with different edentulous time in the first molar area, in order to provide meta reference and guidance for the preoperative design of dental implant. Part I Measurement and analysis of bone mineral density in different edentulous areas with CBCTObjective: This study aims to apply special cone beam CT(CBCT), measure and analyze bone mineral density in different edentulous areas. according to the measured results and statistical data to evaluate the change and rule about alveolar bone density, in order to make preoperation plan and make a prompt about dental implants risks.Methods: 1 clinical data collectionIn hebei province shijiazhuang qiaoxi stomatological hospital and CBCT films of 82 cases who is conforming CBCT imaging data were retrospectively analyzed from May 2013 to December 2014. Men in 42,Women 40 cases, with an average age of 44.7 + /- 5.6 years old.Missing teeth, a total of 135.Use of CBCT on 135 missing tooth alveolar bone imaging data for precise measurement.Left and right side the same tooth bit into a region.The situation of the missing tooth bit see Table 1. 2 experimental apparatusUsing the pax- uni3 D mouth with cone beam CT produced by yiyou company of Korea.90 kv, ma, 360 degree scanning, imaging range 8 * 5 cm.Scanning image reconstruction with Ez3 D plus professional software, the area of jaw bone mass and bone mineral density measurement. 3 measurement methods 3.1 calibrationPatient upright, the body relax, normal occlusion, facial midline vertical to the ground, andocclusal plane parallel to the ground, head frame fixed head position,When shooting, set and the selection will be planting area, positioning as center, and then on the shooting, all patients experienced by the same Radiology technicians under the condition of the same scan. 3.2 measurementTo measure the alveolar bone density in sagittal section. Three sites were maesured: at the top, the root, and midpoint of the alveolar ridge respectively. All sites should be measured three times, and get mean bone density data, bone density results recorded in Hounsfield units(HU). 3.3 The data processing and statistical analysis using SPASS16.0 software. Analysis of different regional differences in bone mineral density using the Mann- Whitney U test, and analysis the relationship between bone density and edentulous areas.Result:Bone mineral density values of mandibular(an average of 124.55 ± 12.81) is greater than the upper jaw(average 97.11 ± 12.44),bone mineral density values of front teeth area(an average of 118.18 ± 13.10) is greater than the area of posterior teeth(an average of 103.49 ± 12.15).Among them the area of posterior teeth of upper jaw, the average density is the smallest(88.55 ±12.55).The area of anterior teeth the average density is slightly larger(105.67±12.34).The posterior teeth of lower jaw is larger then the area of anterior teeth(118.43±11.76).The area of the anterior teeth of mendible is the largest(130.68±13.87). Difference of bone mineral density in different edentulous areas, was statistically significant(P<0.05).Conclusions:CBCT images can show the bone anatomical shape clearly, and provide important information of jaw bone mineral density.Our Research shows that bone mineral density in maxillary posterior teeth area is the minimum relatively, which mind us to prepare for different diamiter of implant holes and cooperate with bone extrusion operation. In the mandibular front teeth area, bone mineral density is the highest, which mind us that bone mineral density is not the focus in this area,we should pay more attention to bone mass measurement. Part II Measurement and analysis about the relationship between the first molar edentulous area and teeth missing timeObjective: This study aims to apply special cone beam CT(CBCT) for the first molar area, alveolar fragments of bone mass(height, width) of bone, observing according to the measured results and statistical data to determine the implant models, to the area dental implants risks to make a prompt.Methods: 1 clinical data collectionIn hebei province shijiazhuang qiaoxi stomatological hospital and CBCT films of 135 cases,41 cases of conforming CBCT imaging data were retrospectively analyzed from May 2013 to December 2014.As shown in Table 1,19 cases maxillary first molars, mandibular first molar 22 cases, the time of missing teeth is between 3 months to 3 years. 2 experimental apparatusUsing the pax- uni3 D mouth with cone beam CT produced by yiyou company of Korea.90 kv, ma, 360 degree scanning, imaging range 8 * 5 cm.Scanning image reconstruction with Ez3 D plus professional software, the area of jaw bone mass and bone mineral density measurement. 3 measurement methods 3.1 calibrationPatient upright, the body relax, normal occlusion, facial midline vertical to the ground, andocclusal plane parallel to the ground, head frame fixed head position,When shooting, set and the selection will be planting area, positioning as center, and then on the shooting, all patients experienced by the same Radiology technicians under the condition of the same scan. 3.2 measurementIn the coronal section, measurable jaw bone height, from the alveolar ridge top to the end(to Anterior teeth the end point is the nasal floor, to posterior teeth of upper jaw the end is the bottom of the maxillary sinus, to the posterior tooth of mandible the end point is the inferior alveolar nerve).In the axial plane, can measure the width of jaw, namely the labial side(buccal) bone cortex to lingual palatal side the distance of the bony cortex. 3.3 The data processing and statistical analysis using SPASS16.0 software, test analysis of different regional differences in bone mineral density and bone massusing the Mann- Whitney U test.And analyze the relationship between bone density and situation of parts, and the time between the missing teeth.Result:For maxillary first molar area, for lack of time for 3 months to a year of patients,the width and height of alveolar bone is the largest(the average width is 9.3 + /- 1.8, the average height is 11.2 + /- 2.1 mm).For lack of time for 2 years to 3 years of patients,the width and height of alveolar bone is the smallest(the average width is 7.6+ /- 1.4, the average height is 9.3 + /-1.8mm).For mandibular first molar area,for lack of time for 3 months to a year of patients,the width and height of alveolar bone is the largest(the average width is 9.1+ /- 1.8, the average height is 12.1 + /- 2.4mm).For lack of time for 2 years to 3 years of patients,the width and height of alveolar bone is the smallest(the average width is 6.2+ /- 1.3, the average height is 8.9+ /-0.9mm).The first molar area bone mass compared with in different situation of time difference was statistically significant(P < 0.05),Longer duration of missing teeth, jaws width and height values gradually decline.Conclusions:CBCT images can clearly show the bone anatomical shape, providing important information of jaw bone mass.The height and width of jaw determines when planting surgery implant length and diameter. For growing design preoperative and postoperative assessment has important guiding significance. |
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