• Journal of Periodontal and Implant Science
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• v.52 no.5
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• pp.411-421
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• 2022

Purpose: In this study, we aimed to evaluate the degree of heat generation when a novel drill design with an irrigation slot was used with metal sleeve-free (MF) and metal sleeve-incorporated (MI) surgical guides in an environment similar to that of the actual oral cavity. Methods: A typodont with a missing mandibular right first molar and 21 bovine rib blocks were used. Three-dimensional-printed MF and MI surgical guides, designed for the placement of internal tapered implant fixtures, were used with slot and non-slot drills. The following groups were compared: group 1, MI surgical guide with slot drill; group 2, MI surgical guide with a non-slot drill; and group 3, MF surgical guide with a slot drill. A constant-temperature water bath at 36℃ was used. The drilling was performed in 6 stages, and the initial, highest, and lowest temperatures of the cortical bone were measured at each stage using a non-contact infrared thermometer. Results: There were no temperature increases above the initial temperature in any drilling procedure. The only significant difference between the non-slot and slot groups was observed with the use of the first drill in the MI group, with a higher temperature in the non-slot group (P=0.012). When the heat generation during the first and the second drilling was compared in the non-slot group, the heat generation during the first drilling was significantly higher (P<0.001), and there was no significant difference in heat generation between the drills in the slot group. Conclusions: Within the limitations of this study, implant-site preparation with the surgical guide showed no critical increase in the temperature of the cortical bone, regardless of whether there was a slot in the drill. In particular, the slotted drill had a cooling effect during the initial drilling.

• The Journal of Advanced Prosthodontics
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• v.14 no.5
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• pp.294-304
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• 2022

PURPOSE. The purpose of this study was to evaluate the influence of different palatal vault configurations on the accuracy and scan speed of intraoral scans (IO) of completely edentulous arches. MATERIALS AND METHODS. Three different virtual models of a completely edentulous maxillary arch with different palatal vault heights- Cl I moderate (U-shaped), Cl II deep (steep) and Cl III shallow (flat)-were digitally designed using CAD software (Meshmixer; Autodesk, USA) and 3D-printed using SLA-based 3D-printer (XFAB; DWS, Italy) (n = 30; 10 specimens per group). Each model was scanned using intraoral scanner (Trios 3; 3Shape^TM, Denmark). Scanning time was recorded for all samples. Scanning accuracy (trueness and precision) were evaluated using digital subtraction technique using Geomagic Control X v2020 (Geomagic; 3DSystems, USA). One-way analysis of variance (ANOVA) test was used to detect differences in scanning time, trueness and precision among the test groups. Statistical significance was set at α = .05. RESULTS. The scan process could not be completed for Class II group and manufacturer's recommended technique had to be modified. ANOVA revealed no statistically significant difference in trueness and precision values among the test groups (P=.959 and P=.658, respectively). Deep palatal vault (Cl II) showed significantly longer scan time compared to Cl I and III. CONCLUSION. The selection of scan protocol in complex cases such as deep palatal vault is of utmost importance. The modified, adopted longer path scan protocol of deep vault cases resulted in increased scan time when compared to the other two groups.

• The Journal of Advanced Prosthodontics
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• v.16 no.4
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• pp.201-211
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• 2024

PURPOSE. The aim of this prospective clinical study was to compare the influence of palatal vault forms on accuracy and speed of intraoral (IO) scans in completely edentulous cases. MATERIALS AND METHODS. Based on the palatal vault form, participants were divided into three equal groups (n = 10 each); Class I: moderate; Class II: deep; Class III: flat palatal vault. A reference model was created for each patient using polyvinylsiloxane impression material. The poured models were digitized using an extraoral scanner. The resultant data were imported as a solid CAD file into 3D analysis software (GOM Inspect 2018; Gom GmbH, Braunschweig, Germany) and aligned using the software's coordinate system to determine its X, Y, and Z axes. Five digital impressions (DIs) of maxilla were captured for each patient using an intraoral scanner (TRIOS; 3Shape A/S, Copenhagen, Denmark) and the resultant Standard Tessellation Language (STL) scan files served as test models. Trueness was evaluated by calculating arithmetic mean deviation (AMD) of the vault area between reference and test files while precision was evaluated by calculating AMD between captured scans to measure repeatability of scan acquisition. The scan time taken for each participant was also recorded. RESULTS. There was no significant difference in trueness and precision among the groups (P = .806 and .950, respectively). Average scan time for Class I and III palatal vaults was 1 min 13 seconds and 1 min 37 seconds, respectively, while class II deep palatal vaults showed the highest scan time of 5 mins. CONCLUSION. Palatal vault form in edentulous cases has an influence on scan time. However, it does not have a substantial impact on the accuracy of the acquired scans.

• The korean journal of orthodontics
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• v.28 no.1 s.66
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• pp.135-142
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• 1998

The purpose of the present study was to evaluate the effect of incisor protrusion on the mucogingival parameters including the width of attached gingiva. Thirty-seven young adults with lower anterior crowding were selected for this study. From the study model, the degrees of relative and absolute protrusions were measured for each lower incisor. Clinical non height, the width of keratinized gingiva, probing depth and the width of attached gingiva were measured with digital vernier calipers and Florida Probe System. Through comparing the difference of the above measurements between protruded and non-protruded incisors, and correlation analysis between each measurement, following results were obtained: 1. The protruded incisor showed narrow width of keratinized and attached gingiva comparing to non-protruded incisor. 2. The protruded incisor showed greater clinical crown height comparing to non-protruded side while there was no difference in the probing depth between protruded and non-protruded side. 3. The difference in the width of attached gingiva between protruded and non-protruded incisors showed higher significance in the lateral incisor than in the central incisor. 4. The degree of relative protrusion showed higher correlation with the width of attached gingiva than the degree of absolute protrusion. 5. Clinical crown height showed higher correlation with the width of attached gingiva than the degree of protrusion.

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.1
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• pp.27-35
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• 2021

Purpose: The purpose of this study is to compare the accuracy of digital scans of implants according to different shapes of scanbodies, and to compare the accuracy of library merging according to different oral exposure height. Materials and methods: A master model with a single tooth edentulous site was prepared. For the first experiment, three types of intraoral scanbodies were prepared, divided into three groups, and the following experiments were conducted for each group: An internal hex implant was placed. The master model with the scanbody connected was scanned with a model scanner, and a master reference file (control group) was created. 10 files (experimental group) were created by performing 10 consecutive scans with an intraoral scanner. After superimposing the control and experimental groups, the following values were calculated: 1) Distance deviation of a designated point on the scanbody 2) Angle deviation of the major axis of the scanbody. For the second experiment, the scanbody scan data were prepared in 6 different heights. Library files were merged with each of the scan data. The distance and angular deviation were calculated using the 7 mm scan data as control group. Results: In the first experiment, there were no significant differences between A and B (P=.278), B and C (P=.568), and C and A (P=.711) in the distance deviations. There were no significant differences between A and B (P=.568), B and C (P=.546), and C and A (P=.112) in the angular deviations. Also, the scanbody showed significantly higher library merging accuracy in the groups with high oral exposure height (P<.5). Conclusion: There were no significant differences in scan accuracy according to the different shapes of scanbodies, and the accuracy of library merging increased according to exposure height of the scanbody in the oral cavity.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.219-224
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• 2019

Purpose: The image registration of radiographic image and digital surface data is essential in the computer-guided implant guide system. The purpose of this study was to examine the effects of using micro-screw on the working time and convenience of operators in the process of image matching for guided implant surgery. Materials and methods: A mandibular dental model was prepared in partial edentulism for Kennedy class I classification. Two micro-screws were placed on the each side of retromolar area. Radiographic and scan images were taken using computed-tomography and digital scanning. The images were superimposed by 12 operators in software in two different conditions: using remaining teeth image alone and using teeth and micro-screws images. Working time, operator convenience and satisfaction were obtained, and analyzed using the Mann-Whitney U test (${\alpha}=.05$). Results: The working time was not statistically different between image registration conditions (P>.05); however, operator convenience and satisfaction were higher in the teeth and micro-screw assisted condition than in the teeth-alone assisted condition (P<.001). Conclusion: The use of micro-screw for the image registration has no effect in working time reduction, but improves operator convenience and satisfaction.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.3
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• pp.233-240
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• 2011

Purpose: To apply a computer assisted navigation system to orthognathic surgery, a simple and efficient measuring algorithm calculation based on affine transformation was designed. A method of improving accuracy and reducing errors in orthognathic surgery by use of an optical tracking camera was studied. Methods: A total of 5 points on one surgical splint were measured and tracked by the Polaris $Vicra^{(R)}$ (Northern Digital Inc Co., Ontario, Canada) optical tracking system in two cases. The first case was to apply the transformation matrix at pre- and postoperative situations, and the second case was to apply an affine transformation only after the postoperative situation. In each situation, the predictive measuring value was changed to the final measuring value via an affine transformation algorithm and the expected coordinates calculated from the model were compared with those of the patient in the operation room. Results: The mean measuring error was $1.027{\pm}0.587$ using the affine transformation at pre- and postoperative situations and the average value after the postoperative situation was $0.928{\pm}0.549$. The farther a coordinate region was from the reference coordinates which constitutes the transform matrixes, the bigger the measuring error was found which was calculated from an affine transformation algorithm. Conclusion: Most difference errors were brought from mainly measuring process and lack of reproducibility, the affine transformation algorithm formula from postoperative measuring values by using of optic tracking system between those of model surgery and those of patient surgery can be selected as minimizing the difference error. To reduce coordinate calculation errors, minimum transformation matrices must be used and reference points which determine an affine transformation must be close to the area where coordinates are measured and calculated, as well as the reference points need to be scattered.

• Imaging Science in Dentistry
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• v.45 no.1
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• pp.15-22
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• 2015

Purpose: This study was performed to assess the reproducibility of identifying the sella turcica landmark in a three-dimensional (3D) model by using a new sella-specific landmark reference system. Materials and Methods: Thirty-two cone-beam computed tomographic scans (3D Accuitomo$^{(R)}$ 170, J. Morita, Kyoto, Japan) were retrospectively collected. The 3D data were exported into the Digital Imaging and Communications in Medicine standard and then imported into the Maxilim$^{(R)}$ software (Medicim NV, Sint-Niklaas, Belgium) to create 3D surface models. Five observers identified four osseous landmarks in order to create the reference frame and then identified two sella landmarks. The x, y, and z coordinates of each landmark were exported. The observations were repeated after four weeks. Statistical analysis was performed using the multiple paired t-test with Bonferroni correction (intraobserver precision: p<0.005, interobserver precision: p<0.0011). Results: The intraobserver mean precision of all landmarks was <1 mm. Significant differences were found when comparing the intraobserver precision of each observer (p<0.005). For the sella landmarks, the intraobserver mean precision ranged from $0.43{\pm}0.34mm$ to $0.51{\pm}0.46mm$. The intraobserver reproducibility was generally good. The overall interobserver mean precision was <1 mm. Significant differences between each pair of observers for all anatomical landmarks were found (p<0.0011). The interobserver reproducibility of sella landmarks was good, with >50% precision in locating the landmark within 1 mm. Conclusion: A newly developed reference system offers high precision and reproducibility for sella turcica identification in a 3D model without being based on two-dimensional images derived from 3D data.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.1
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• pp.49-53
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• 2011

Introduction: This study compared the strength of osseointegration as determined by the resistance to reverse torque rotation of three different hydroxyapatite coated implants in the rabbit femur model. Materials and Methods: Three hydroxyapatite coated implants (HAPTITE), Tapered Screw-Vent (TSV) and BioTite-H - were used. A total of 40 implants were placed in the femur of 20 adult male rabbits. The animals were divided into two groups. In group A (n=10); one HAPTITE was placed into each right femur and one TSV was placed into each left femur. In group B (n=10); one HAPTITE was placed into each right femur and one BioTite-H was placed into each left femur. Five rabbits of each group were sacrificed at 4 and 8 weeks. The implants were removed by reverse torque rotation using a digital torque-measuring device. A total of 40 implants in 20 rabbits were used for the removal torque measurements. Results: In the Group A, 4 weeks after implant placement, the mean removal torque for the HAPTITE and TSV was $70.7{\pm}31.6$ N cm and $28.9{\pm}15.1$ N cm, respectively. Eight weeks after implant placement, the mean removal torque for the HAPTITE and TSV was $87.9{\pm}26.2$ N cm and $54.9{\pm}22.4$ N cm, respectively. In the Group B, 4 weeks after implant placement, the mean removal torque for the HAPTITE and BioTite-H was $58.0{\pm}29.6$ N cm and $37.7{\pm}14.1$ N cm, respectively. Eight weeks after implant placement, the mean removal torque for the HAPTITE and BioTite-H was $91.4{\pm}47.1$ N cm and $30.8{\pm}9.8$ N cm. HAPTITE showed a higher removal torque than the other implants. Conclusion: These results suggest that HAPTITE increases the strength of osseointegration significantly as determined by the resistance to reverse torque rotation.

• Restorative Dentistry and Endodontics
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• v.31 no.5
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• pp.371-377
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• 2006

The purposes of this study were to assess the accuracy of measurements in pre-enlarged canals with small instruments and to compare the accuracies, in enlarged canal, with small size instruments and instruments that match the actual canal diameter using Root ZX, Bingo1020, SmarPex, and e-Magic Finder. Ten extracted teeth were embedded in an alginate model made for testing apex locators. A size 10 file was placed into the root canal until the tip of the file reached the plane of the major diameter of the foramen under a dental operating microscope at the 25 x magnification. The measurement was done with digital caliper and defined as actual length. Electronic length measurement with a size 10 file in pre-enlarged canal was done by reading the index indicating Apex of each device to gain a definite value After completion of canal enlargement to a size 45 file, each difference between actual length and electric measurement value with a size 10 and 40 files in enlarged canal was recorded as L10 and L40. The one-way ANOVA and Scheffe's multiple range tests were computed for analyze the differences among the four apex locators in the same group. The Student's t-test between L10 and L40 of each locator was done. The accuracies of electronic measurements were significantly different among the 4 devices. The file size made no difference on the accuracy of electronic measurement in enlarged canal with same device. The e-Magic Finder was the most accurate device among the 4 apex locators used in this study.