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Cone beam computed tomography cbct to assess bone density

Correspondence should be addressed to Corina Marilena Cristache ; moc. This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Despite numerous advantages over multislice computed tomography MSCTincluding a lower radiation dose to the patient, shorter acquisition times, affordable cost, and sometimes greater detail with isotropic voxels used in reconstruction, allowing precise measurements, cone beam computed tomography CBCT is still controversial regarding bone quality evaluation.

Case Reports in Dentistry

This paper presents a brief review of the literature on accuracy and reliability of bone quality assessment with CBCT and a case report with step-by-step predictable treatment planning in esthetic zone, based on CBCT scans which enabled the clinician to evaluate, depending on bone volume and quality, whether immediate restoration with CAD-CAM manufactured temporary crown and flapless surgery may be a treatment option.

Introduction Nowadays, cone beam computed tomography CBCT systems replaced multislice computed tomography MSCT for dental treatment and planning due to many advantages offered, including a lower radiation dose to the patient, shorter acquisition times cone beam computed tomography cbct to assess bone density 12 ], affordable cost, better resolution, and sometimes greater details [ 34 ].

CBCT uses isotropic voxels and, as a result, measurements are precise and considered 1: Despite these preference factors, the reliability, consistency, and accuracy of CT numbers derived from CBCT imaging systems in bone quality evaluation remain controversial [ 6 ].

The imprecision of the intensity values of CBCT systems is commonly attributed to differences in characteristics of the devices kVp, mA, exposure timethe imaging parameters voxel sizeand the position or field of view FOV of the area being evaluated [ 78 ]. Several studies [ 6 — 9 ] performed on homogenous phantoms and nonhomogenous materials cone beam computed tomography cbct to assess bone density to human tissues using different CBCT scanners demonstrated linear correlation between CBCT gray scale and HU.

Other studies [ 10 — 13 ] focused on investigating the relation between bone characteristics obtained from CBCT scan and primary stability of the implants found a direct correlation between VVs, insertion torque value ITVand implant stability quotient ISQ. They also stated that preoperative cone beam computed tomography cbct to assess bone density of density values by CBCT was a reliable tool to objectively determine bone density. The aim of the clinical report presented is to describe a sequence of minimally invasive treatment procedures for predictable immediate placement and restoration of a dental implant replacing a temporary maxillary canine.

Decision of immediate implant placement in fresh extraction socket and restoration was based upon an CBCT evaluation of bone characteristics volume and quality prior to implant surgery. Case Presentation A 31-year-old woman was referred by her general dentist to our dental implant department after being evaluated by the orthodontist.

The clinical and radiological examination revealed a retained upper left primary canine tooth, agenesis of 22, permanent cusped 23 in transposition with mesiovestibular rotation.

On the contralateral side a peg lateral incisor 12 was present. The mid-facial gingival margin of 63 was slightly lower than transposed 23 and that of the contralateral tooth Figures 1 a and 1 b. The gingival tissue surrounding the crown was measured with a periodontal probe and characterized as thick [ 16 ].

Interproximal papilla was present and underlying bone level was at 1. On the right maxillary arch a peg lateral incisor is present.

Gingival biotype was determined as being thick. Distovestibular rotation of transposed 23 is observed. There were no medical contraindications, and patient agreed with dental implant treatment and signed the written consent form. Treatment Protocol Alginate and Tropicalgin Zhermack, Italy impression of the surgical site and the opposite arch for stone models was taken using standard trays.

Maximum intercuspal position was registered with vinyl polysiloxane bite registration material Regisil, Dentsply, USA. This option provides automat conversion of CBCT gray scale in 5 basic colors, corresponding to the 256 shades of gray, from the CBCT scan, visible on computer monitors. The temporary screw-retained crown was designed according to the planned position of the implant and was sent as STL file for evaluation by the patient and the restorative team Cone beam computed tomography cbct to assess bone density 1 e.

Manufacturing of the Stereolithographic Surgical Template and Temporary Screw-Retained Crown Surgical template was printed according to the established position of the implant, which was simulated in alveolar bone by the R2GATE software based on the obtained CBCT data, estimated bone quantity and quality, and digital wax-up of the future prosthetic reconstruction.

Screw-retained cone beam computed tomography cbct to assess bone density was manufactured according to the planed implant position and delivered before surgery with the computer aided design and manufacturing CAD-CAM surgical template Figures 2 a and 2 b.

Surgery and Provisional Crown Atraumatic extraction of the primary canine using periotomes was performed Figures 2 c and 2 d. Care was taken not to damage the labial bone, the socket was irrigated with saline, and the site was examined to verify an intact buccal plate.

Insertion drill sequence was recommended cone beam computed tomography cbct to assess bone density the manufacturer according to the bone characteristics evaluated with the aid of the CBCT in order to acquire maximum bone to implant contact.

Torque insertion value was 65N cm resulting in a good primary stability. The space between the inner surface of the labial osseous wall and the labial surface of the implant was filled with resorbable bovine bone graft material Cerabone, Botiss, Germany.

After implant insertion cone beam computed tomography cbct to assess bone density prefabricated provisional crown was screwed into the implant and occlusal adjustments were performed Figure 3 a. Eight weeks after implant surgery, after uneventful osseointegration, the provisional crown was unscrewed and an excellent healing of dentogingival complex and papilla preservation were observed Figure 3 b. Patient was very pleased with the final result Figures 4 a and 4 b.

No bone resorption was noticed. Distal and mesial papilla are present. WES score is 9 due to nonperfect resemblance of the restored canine. At the annual recall the implant showed no signs of complications nor infection Figure 4 c.

Discussions Primary implant stability is the key factor for immediate restoration and it is obvious that attention should be paid to the local bone quantity and quality during the presurgical planning phase [ 19 ].

For bone volume, it is well known that CBCT provides submillimeter isotropic voxels allowing accurate measurements, with minimal magnification and distortion error less than 0.

Bone quality on CBCT, prior to implant cone beam computed tomography cbct to assess bone density, even though not being quantifiable in reproducible unit e. Moreover, they established, in pristine maxillary bone, some regression equations allowing clinicians to preoperatively estimate the microstructure of the maxillary bone based on a mean bone density value assessed by CBCT [ 22 ].

Therefore a temporary crown can be manufactured prior to implant insertion to facilitate immediate implant restoration especially for the high requirements in esthetic zone [ 23 ]. Due to the fact that the eye and the monitor display are not able to handle 4096 212 shades of gray obtained from a CBCT scan computer monitor is able to display only 255 shades of gray and human eye can clearly distinguish between 8 and 16 [ 24 ]the R2GATE software automatically converts gray shades, measuring X-ray absorption, in a range of 5 basic colors.

Human eye sensitivity is limited for gray shades but is able to distinguish 128 fully saturate hues and with the addition of white light to hue enables discernment of a number of 350. Intensity transformations are the most commonly used image processing techniques, enabling image data adjustments for better visualization.

Therefore a scale has to be mapped to display intensity values that extends from 0 to 255 and the conversion is usually done with a linear function. As the window with decreases, the contrast in the displayed image increases. As the window level moves cone beam computed tomography cbct to assess bone density downthe image becomes darker lighter.

This operation is called windowing leveling and adjusts brightness and contrast for a better visualization, without changing the original data of the CBCT [ 26 ]. R2GATE software, used for treatment planning in the presented case report, allows changing the values of colors displayed on the screen contrast control using windowing in order to better visualize the volume of interest, outbalancing the limitations of human eyes and computer monitors.

Moreover, the color-coded bone density assessment enables the clinician to establish an individualized drilling protocol in order to improve dental implant primer stability. Guided surgery is advantageous for conventional implant placement, immediate implant placement, and potential immediate provisionalisation. The advantage of cone beam computed tomography cbct to assess bone density stage immediate implant placement is more predictable preservation of the peri-implant gingival tissue [ 29 ] with less patient discomfort and less treatment time [ 30 ].

The criteria and techniques for proper immediate implant placement have previously been established and reported with successful long-term outcomes [ 3132 ].

In order to compensate for the expected horizontal bone resorption of the buccal plate, the use of bone substitutes, with a low resorption rate, to cone beam computed tomography cbct to assess bone density the gap has been shown to reduce this resorption significantly and therefore their use should be advocated when the esthetic demands are high [ 37 ].

Immediate implant placement and restoration not only reduced the number of necessary surgeries but also decreased treatment time and costs and is recommended to be utilized each time local and systemic condition permits [ 38 ]. Conclusions This case report presented step by step a straightforward, predictable, treatment planning, based on CBCT scans, which enables the clinician to evaluate whether immediate restoration and flapless surgery may be a treatment option and allows CAD-CAM manufacturing of a temporary crown with adequate subgingival contour in order to preserve soft tissue architecture.

The decision of immediate implant placement and manufacturing provisional crown can rely on CBCT bone quality assessment during the presurgical implant-planning phase [ 19 ]. The use of CBCT gray scale automate conversion in 5 colors and the windowing process allows the clinician for a better evaluation of bone characteristics for a precise implant planning and crown fabrication. But final decision on immediate restoration can be taken only at the time of surgery, after objective evaluation of primary implant stability.

Competing Interests The author declares that she has no competing interests. View at Google Scholar D. View at Google Scholar J.