Accuracy of densitometry of two cone beam computed tomography equipment in comparison with computed tomography

Feasibility of CBCT in Diagnosing Otosclerosis by Measuring CBCT Bone Density: A Preliminary Study

The aim of this study was to measure cone beam computed tomography (CBCT) derived bone density of 6 anatomic points around the otic capsule in preoperative assessment of patients with clinically suspected otosclerosis, and to compare these densities with control group. CBCT images of 21 patients (34 ears, the otosclerosis group) with surgically confirmed otosclerosis and 26 patients (52 normal ears, the control group) were evaluated in this prospective study. Six regions of interest (ROI) were set manually around the otic capsule with the slice thickness of 0.3 mm. The mean CBCT bone density these regions were measured and compared in the case and control groups. In the case group, the mean CBCT bone density at the fissula ante fenestram (FAF) was significantly lower than the control group. Moreover, at the 4 points of the other ROIs (3-6) CBCT bone densities were significantly lower in the case group compared to the control group (p < 0.01). In this group, among 13 bilateral otosclerosis, 22 ears had conductive hearing loss (CHL), 4 ears had mixed hearing loss (MHL) and among 8 unilateral otosclerosis, 5 ears had CHL, 3 ears had MHL. Our study showed the mean CBCT bone density of ROIs 1 and 6 were correlated with the average air-bone gap in the bilateral and unilateral otosclerosis group, respectively. Quantitative evaluation of CBCT with a slice thickness of 0.3 mm can be used as a suitable tool for diagnosis and follow-up of otosclerosis in temporal bone.

Optimised Implant Selection Using Digital Volume Tomography (DVT) Osteodensitometry

Purpose

The density of the jaw bone has an inhomogeneous distribution and, even within partial volumes, varies more or less strongly from the size of typical implants. Consequently, the primary stability of implants using conventional techniques can only ever be determined postimplantation. The aim of the present case report is to present digital volume tomography (DVT) osteodensitometry as a procedure for assessing the primary stability preimplantation and to evaluate its benefits.

Methods

An orthopantomogram (OPT) and vertical sections, including bone density measurement, were obtained from a DVT in the course of preimplantological diagnosis. Conventional implant planning and densitometric simulation were performed on this basis.

Results

Densitometric simulation enabled assessment of the bone density at the interface to the implant body preimplantation. This procedure provides not only an overall value (averaged density) but also allocation of bone areas with different densities to the adjacent areas on the implant surface. This then allows the implant with the best possible macroscopic geometry and optimum position to be selected, with the aim of maximising primary stability. In the present case, the maximum torques during insertion confirmed the densitometric values recorded in advance.

Conclusion

DVT osteodensitometry enables selection of an implant optimised to bone density distribution. At the same time, the point at which loading occurs can already be defined at the planning stage, thanks to the predictable primary stability. A standard integration of DVT osteodensitometry in the algorithms of implant planning software thus seems desirable.

[Progress of research on cone beam CT in cochlear implantation]

Cochlear implant, as the most successful artificial auditory implant, brings tens of thousands of patients with severe or profound sensorineural hearing loss back to the world of sound every year. With the expansion of surgical indications, a large number of difficult cases bring new challenges for cochlear implantation. As a new technology, cone beam CT has the double advantages of high spatial resolution and low radiation. It is considered as the second revolution of CT technology, which shows unique value in the application of cochlear implantation. This article reviews the basic principles of cone beam CT and its application and research progress in cochlear implantation.

Biphasic Calcium Phosphate Microparticles Mixed With Autologous Blood: Application for the Reconstruction of a Large Mandibular Bone Defect in a Dog

Large mandibular bone defects can be difficult to treat in dogs, with a high risk of mal or nonunion due to instability and risk of infection. This case report describes the use of autologous clotted blood mixed with biphasic calcium phosphate microparticles to fill a defect in a nonunion fracture and promote bone regeneration in a dog using a 2-stage surgical approach. This new method was designed and tried in a dog with a chronic, unstable mandibular fracture associated with a large sequestrum. Initial treatment involved debridement of the lesion, then the oral wound and oral vestibule were reconstructed in 2 layers. Four weeks later a second stage surgery allowed placement of a pre-contoured maxillofacial plate to bridge the defect, which was filled with a blood/biphasic calcium phosphate compound implant. Cone-beam computed tomography was used prior to the initial surgery for preoperative planning and 3-D printing of a mandibular template for plate contouring. CT was subsequently used to document the healing process, using a bone density measurement tool to assess bone regeneration. Radiographic evidence suggestive of osseointegration was observed within 6 months with effective filling of the defect and restoration of alveolar ridge continuity. A return to normal and atraumatic occlusion was considered excellent. Cone-beam computed tomography was found useful to document radiographic evidence of osseointegration, bone regrowth and remodeling. This case report is to serve as a proof-of-concept study and should be followed by a prospective evaluation.

The Use of Biphasic Calcium Phosphate Substitute (BCP) in Mandibular Defects in Dogs: Use of CBCT to Evaluate Bone Healing

This study aimed to assess the use of cone beam computed tomography (CBCT) to follow-up bone healing of mandibular bone defects in dogs, filled with a combination of autologous blood and millimetric BCP granules. CBCT was performed ≥4 weeks postoperatively. CBCT gray-scale values were measured from multiplanar reconstructions of the defects and compared to that of normal contralateral mandibular bone and to pure BCP/blood composite time 0 (T0) value. Other parameters, determined by affecting grades according to specific criteria included: bone ridge margin restoration; biomaterial homogeneity; bone-biomaterial interface. Results: 8 dogs with 14 defects were included. Median age was 7.2 years (1-15 years). Follow-up CBCT was performed 1 to 7.5 months postoperatively (mean 3.3 months). Defect CBCT gray-scale values at follow-up were significantly greater than T0 (p < 0.05). Ratios of maximum and minimum densities of the defects to contralateral mandibular bone followed a linear correlation with time (p < 0.05). The bone ridge margin was adequately restored in all the defects and significantly correlated with time (p = 0.03). Biomaterial homogeneity was fair to good in 11 defects and significantly correlated with the bone ridge margin parameter (p = 0.05) and time (p = 0.006). There was no significant correlation with the bone-material interface. The latter was satisfactory in 12 defects and significantly correlated with time (p = 0.01) but not with the other parameters. The biomaterial was more homogeneous in smaller defects and with increasing time. CBCT allowed effective assessment of bone healing via the measurement of CBCT gray-scale values and assessment of multiple radiological variables.

Facial alveolar bone alterations and gray value changes based on cone beam computed tomography around maxillary anterior implants: A clinical retrospective study of 1-3 years

OBJECTIVES

The purpose of this cone beam computed tomography (CBCT) study was to describe facial alveolar bone alterations and gray value (GV) changes around implants in aesthetic anterior maxilla with simultaneous guided bone regeneration (GBR) and to investigate potential influence of factors related to vertical alveolar bone stability, such as particle sizes of the deproteinized bovine bone mineral (DBBM) used.

MATERIALS AND METHODS

A retrospective study design was adopted. Four facio-palatal cross-sectional CBCT images of 166 implants from 124 patients who had maxillary anterior implants were obtained. Measurements of the vertical facial alveolar bone level (VFBL), horizontal facial alveolar bone thickness (HFBT), and GV were identified of 1-3 years. Then, correlation coefficients for those parameters were calculated. Finally, linear mixed models were established to investigate potential factors influencing vertical alveolar bone resorption.

RESULTS

Facial alveolar bone underwent fast bone modeling and remodeling during the first 6 months, with decreases of 1.00 ± 1.19 and 0.74 ± 0.86 mm in VFBL and HFBT in implant shoulder, respectively, and there was positive and significant correlation between the alterations in VFBL and HFBT1 (r_s  = .516, p = .000). Linear mixed models identified particle size of DBBM as a critical factor associated with vertical bone resorption (p = .000). The GV gradually increased during the follow-up period.

CONCLUSIONS

Rapid and unavoidable peri-implant bone resorption usually happened during the first 6 months after implant placement. GBR is a predictable treatment for maxillary anterior implants, since GV has an increasing trend. Large bone particles of DBBM help maintain vertical alveolar bone stability.

Digital reconstruction of teeth using near-infrared light

Cone beam computed tomography has demonstrated value by offering enhanced conceptualization of features of teeth in the 3D space. However, these systems require higher effective radiation doses to image teeth. Previous research from our group has used non-ionizing near-infrared (NIR) light for diagnosing demineralization and caries in human tooth enamel. However, use of safe NIR radiation for rapid, 3D imaging of tooth anatomy has not been described previously. Here we describe a optical setup to rapidly laser scan teeth ex vivo using 1310nm NIR laser diode. We also detail a novel process that uses laser scanning to create stacks of images of extracted teeth, and construct highly accurate 3D models. Our 3D reconstructive models offer promising starting points to recover anatomical details using pixel intensities within these images as projection data to diagnose carious lesions, and can assist in providing rapid and affordable technology-enabled early caries screenings to patients.