Novel geometric coordination registration in cone-beam computed tomogram

Paper ID: AIPR-140701-9The use of cone-beam computed tomography (CBCT) in medical field can help the clinicians to visualize the hard tissues in head and neck region via a cylindrical field of view (FOV). The images are usually presented with reconstructed three-dimensional (3D) imaging and its orthogonal (x-, y-and z-planes) images. Spatial relationship of the structures in these orthogonal views is important for diagnosis of diseases as well as planning for treatment. However, the non-standardized positioning of the object during the CBCT data acquisition often induces errors in measurement since orthogonal images cut at different planes might look similar. In order to solve the problem, this paper proposes an effective mapping from the Cartesian coordinates of a cube physically to its respective coordinates in 3D imaging. Therefore, the object (real physical domain) and the imaging (computerized virtual domain) can be linked up and registered. In this way, the geometric coordination of the object/imaging can be defined and its orthogonal images would be fixed on defined planes. The images can then be measured with vector information and serial imagings can also be directly compared. © 2014 IEEE.published_or_final_versio

Image calibration and registration in cone-beam computed tomogram for measuring the accuracy of computer-aided implant surgery

Medical radiography is the use of radiation to “see through” a human body without breaching its integrity (surface). With computed tomography (CT)/cone beam computed tomography (CBCT), three-dimensional (3D) imaging can be produced. These imagings not only facilitate disease diagnosis but also enable computer-aided surgical planning/navigation. In dentistry, the common method for transfer of the virtual surgical planning to the patient (reality) is the use of surgical stent either with a preloaded planning (static) like a channel or a real time surgical navigation (dynamic) after registration with fiducial markers (RF). This paper describes using the corner of a cube as a radiopaque fiducial marker on an acrylic (plastic) stent, this RF allows robust calibration and registration of Cartesian (x, y, z)- coordinates for linking up the patient (reality) and the imaging (virtuality) and hence the surgical planning can be transferred in either static or dynamic way. The accuracy of computer-aided implant surgery was measured with reference to coordinates. In our preliminary model surgery, a dental implant was planned virtually and placed with preloaded surgical guide. The deviation of the placed implant apex from the planning was x=+0.56mm [more right], y=- 0.05mm [deeper], z=-0.26mm [more lingual]) which was within clinically 2mm safety range. For comparison with the virtual planning, the physically placed implant was CT/CBCT scanned and errors may be introduced. The difference of the actual implant apex to the virtual apex was x=0.00mm, y=+0.21mm [shallower], z=-1.35mm [more lingual] and this should be brought in mind when interpret the results

Impact of complications of single tooth fixed restorations on OHRQoL

Sesssion: Prosthodontics : no. 168774OBJECTIVES: To compare oral health-related quality of life (OHRQoL) among subjects treated with implant supported crowns (ISC) and 2-unit cantilevered resin bonded bridges (cRBB), and to investigate factors associated with their OHRQoL. METHODS: A case-control study was conducted of subjects who had received ISC or cRBB treatments. Clinical examination and interview was undertaken to determinate restoration status. OHRQoL was assessed using the Oral Health Impact Profile (OHIP) and analysed by Mann-Whitney U-test and Kruskal-Wallis one-way ANOVA. Negative binominal regression was conducted to investigate the factors associated with OHIP-49 score. RESULTS: 78 subjects controlled with restoration age and location were recruited (39 ISCs and 39 cRBBs). There are no significant difference in OHIP scores between ISC and cRBB (P>0.05) and between survived and failed (Failure Complication, FC) (P>0.05). There is significant higher score in domain physical disability for success (No Complication, NC) than presence of complications i.e. poorer OHRQoL (P=0.005). These survived but not success (Non-Failure Complication, NFC) have lowest OHIP-49 score (P=0.017). For ISCs, while NFC has only lower score in domain physical pain than NC, it has lower scores in domain functional limitation, physical pain, handicap and OHIP-49 score than FC (P<0.05). For cRBBs, NFC has lower score in domain physical disabilitythan NC (P=0.006). Regression analysis suggested the NFC (when compared to NC) was significantly associated with OHIP-49 score with a rate ratio 0.79 (unadjusted, CI: 0.69 – 0.91) and 0.81 (adjusted, CI: 0.70 – 0.94) (P<0.05). CONCLUSIONS: ISC and cRBB show similar overall impact to OHRQoL. The impact of complications may vary between ISC and cRBB. However NFC may not have negative impact on subject’s OHRQoL

Distal Extension Denture &ndash; Case Report and Overview [Corrigendum]

Yeung C, Leung KCM, Yu OY, Lam WYH, Wong AWY, Chu CH. Clin Cosmet Investig Dent. 2020;12:493&mdash;503. &nbsp; Details of the same case report were previously reported by the authors in Yeung C, Leung KCM, Yu OY, Lam WYH, Wong AWY, Chu CH. Prosthodontic Rehabilitation and Follow-Up Using Maxillary Complete Conventional Immediate Denture. Clin Cosmet Investig Dent. 2020;12:437&ndash;445. Figures 1-5, 11 and 12-14 on pages 494, 496 and 497, respectively, should have included the following note: Note: Copyright &copy;2020. Dove Medical Press. Reproduced from Yeung C, Leung KCM, Yu OY, Lam WYH, Wong AWY, Chu CH. Prosthodontic Rehabilitation and Follow-Up Using Maxillary Complete Conventional Immediate Denture. Clin Cosmet Investig Dent. 2020;12:437&ndash;445. &nbsp; Read the original articl

Contemporary epidemiology of nasopharyngeal carcinoma: a life course perspective

Conference Theme: integration and collaboration - the way forwardSymposium: Public Health Perspectives on Cancer Treatment and ControlThe 18th Hong Kong International Cancer Congress (HKICC 2011), Hong Kong, 3-5 November 2011

Long-term clinical evaluation of 211 two-unit cantilevered resin-bonded fixed partial dentures

Abstract Objectives This retrospective study aims to evaluate the long term clinical performance of two-unit cantilevered resin-bonded fixed partial dentures (RBFPDs) relating to their retention, success and survival rate. Materials and methods Prostheses that were placed at least four years previously were clinically reviewed to evaluate retention, success and survival rate. Additional information was also collected, including patient's gender, age and satisfaction on their prosthesis, operator's experience, prosthesis service life, root canal therapy if performed, abutment mobility, bone support, the presence of shim-stock contacts on the abutment or pontic in intercuspal position, and the presence of proximal axial contacts adjacent to the prosthesis. The date of any debonding with subsequent treatment was also recorded. Results A total of 211 two-unit RBFPDs were placed in 153 patients, with a mean service life of 113.2 ± 33.5 months. Twenty-eight prostheses debonded, resulting in a retention rate of 86.7 percent, and another five teeth were extracted with the prostheses, resulting in a success rate of 84.4 percent. 90.0 percent prostheses were functioning (survival rate) by means of rebonding at the time of review. The location of the replaced tooth had a significant effect on the retention of RBFPDs with posterior RBFPDs lower than anterior (p = 0.020). Kaplan–Meier analysis revealed 5-, 10- and 15-year cumulative probability of surviving was 0.97, 0.91 and 0.84, respectively. Conclusions 211 two-unit RBFPDs were observed to have a success, retention and survival rate of 84.4, 86.7 and 90.0 percent, respectively, with a mean service life of 9.4 years. Clinical Significance Based on the clinical results, two-unit RBFPD are shown to be a durable prosthesis over the long term with high patient satisfaction. The posterior prostheses, particularly in the lower arch appeared to have a higher failure rate, and improved design features should be considered.link_to_subscribed_fulltex

Home based app for oral muscle exercises (HOE) : a preliminary study

202308 bcchOther VersionOthersNakao Foundation GrantPublishe