Effect of Ambient Lights on the Accuracy of a 3-Dimensional Optical Scanner for Face Scans: An In Vitro Study.

Most 3D scanners use optical technology that is impacted by lighting conditions, especially in triangulation with structured-light or laser techniques. However, the effect of ambient lights on the accuracy of the face scans remains unclear. The purpose of this study is to investigate the effect of ambient lights on the accuracy of the face scans obtained from the face scanner (EinScan Pro 2X Plus, Shining 3D Tech. Co., LTD., Hangzhou, China). A head model was designed in Rhinoceros 5 software (Rhino, Robert McNeel and Associates for Windows, Washington DC, USA) and printed with 200 micron resolution of polylactic acid and was dented with 2.0 mm of carbide bur to aid in superimposition in software. The head model was measured by a coordinate-measuring machine (CMM) to generate a reference stereolithography (STL) file as a control. The face model was scanned four times under nine light conditions: cool white (CW), warm white (WW), daylight (DL), natural light (NL), and illuminant (9w, 18w, 22w). Scan data were exported into an STL file. The scan STL files obtained were compared with the reference STL file by 3D inspection software (Geomagic Control X version 17, Geomagic, Morrisville, NC, USA). The deviations and root mean square errors (RMSEs) between the reference model (trueness) and within the group (precision) were selected for the statistical analysis. The statistical analysis was done using SPSS 20.0 (IBM Company, Chicago, USA). The trueness and precision were evaluated with the one-way ANOVA with multiple comparisons using the Tukey method. For trueness, the scanner showed the lowest RMSE under the NL group (77.18 ± 3.22) and the highest RMSE under the 18w-DL group (95.33 ± 6.89). There was a statistically significant difference between the NL group and the 18w-DL group (p < 0.05) for trueness. Similarly, for precision, the scanner showed the lowest RMSE under the NL group (56.92 ± 4.56) and the highest RMSE under the 9w-CW group (78.52 ± 10.61). There was statistically significant difference between NL, 18w-WW, 18w-CW, 18w-DL, 22w-WW, 22w-DL, 9w-CW, 9w-WW, and 9w-DL (p < 0.05) for the precision. Ambient lights affected the face scans. Under the natural light condition, the face scanner had the best accuracy in terms of both trueness and precision. The 18w-DL and 9w-WW conditions showed the least trueness whereasthe 9w-CW and 9w-DL conditions showed the least precision.

Comparison of Different Types of Static Computer-Guided Implant Surgery in Varying Bone Inclinations.

This research aimed to compare the accuracy of dental implant placement among three types of surgical guide: metal sleeve with key handle (Nobel guide, Nobel Biocare, Göteborg, Sweden), metal sleeve without key handle, and non-sleeve without key handle (Dentium full guide kit, Dentium Co., Seoul, Korea) when placing the implant in different bone inclinations. A total of 72 polyurethane bone models were fabricated in different inclinations (0°, 45°, and 60°). The dental implants were placed in bone models following the company's recommendations. After dental implants were installed, the digital scans were done by an extraoral scanner. The deviations of the dental implant position were evaluated by superimposition between post-implant placement and reference model by using GOM inspect software. The deviation measurement was shown in 5 parameters: angular deviation, 3D deviation at the crest, 3D deviation at the apex, lateral linear deviation, and vertical linear deviation. The data were analyzed using One-way ANOVA and post-hoc tests at a significance level of 0.05. The accuracy of the dental implant position was not significantly influenced by the difference in the surgical guide system (p > 0.05). There were significant differences between placed and planned implant positions in the different inclinations of the bone. A significant difference was found in all parameters of 0° and 60° bone inclinations (p < 0.05). At 0° and 45°, angulated bone showed significant differences except in 3D deviation at the apex. Between 45° and 60° were significant differences only in angular deviation. Within the limitations of this study, the accuracy of implant placement among three types of surgical guides (Non-sleeve without key handle, Metal sleeve without key handle, and Metal sleeve with key handle) from two companies (Dentium and Nobel Biocare) was similar. Hence, the operators can choose the surgical guide system according to their preference. The inclination of bone can influence the angulation of dental implants.

Magnification of Iris through Clear Acrylic Resin in Ocular Prosthesis.

The study on the magnification of the clear acrylic resin in prosthetic dentistry is important but lacking. Hence, this research aimed to investigate the magnification of the iris in the ocular prosthesis with various thicknesses of clear heat cure acrylic resin. A total of 60 ocular prostheses were divided into six groups with various thicknesses of clear heat cure acrylic resin over the iris; T0 (control): no acrylic resin, T1: 2, T2: 4, T3: 6, T4: 8, and T5: 10 mm of clear acrylic resin over the iris. Each ocular prosthesis was manufactured from white acrylic, with a 10.250 mm iris. Then, the clear heat cure resin was placed over the iris, cured, then polished. The final diameter of the iris was measured with a vernier caliper. The sizes of the iris were compared among various groups using one-way ANOVA, and a significant level was chosen at p value = 0.01. The mean sizes of iris were T0 = 10.25, T1 = 10.92, T2 = 11.26, T3 = 11.91, T4 = 12.75, and T5 = 13.43 mm. The size of the iris was significantly different among the group (p < 0.0001). The magnification of the iris for different groups was 1.06 for T1, 1.10 for T2, 1.16 for T3, 1.24 for T4, and 1.31 for T5. The magnification of the iris increased as the thickness of clear heat cure acrylic resin over the iris is increased on the ocular prosthesis.

Wear Resistance, Color Stability and Displacement Resistance of Milled PEEK Crowns Compared to Zirconia Crowns under Stimulated Chewing and High-Performance Aging.

Recently, polyetheretherketone (PEEK) has been introduced to the dental market as a high-performance and chemically inert biomaterial. This study aimed to compare the wear resistance, abrasiveness, color stability, and displacement resistance of zirconia and PEEK milled crowns. An ideal tooth preparation of a first maxillary molar was done and scanned by an intraoral scanner to make a digital model. Then, the prosthetic crown was digitally designed on the CAD software, and the STL file was milled in zirconia (CaroZiir S, Carol Zircolite Pvt. Ltd., Gujarat, India) and PEEK (BioHpp, Bredent GmbH, Senden, Germany) crowns using five-axis CNC milling machines. The wear resistance, color stability, and displacement resistance of the milled monolithic zirconia with unfilled PEEK crowns using a chewing simulator with thermocyclic aging (120,000 cycles) were compared. The antagonist wear, material wear, color stability, and displacement were evaluated and compared among the groups using the Wilcoxon-Mann-Whitney U-test. Zirconia was shown to be three times more abrasive than PEEK (p value < 0.05). Zirconia had twice the wear resistance of PEEK (p value < 0.05). Zirconia was more color stable than PEEK (p value < 0.05). PEEK had more displacement resistance than zirconia (p value < 0.05). PEEK offers minimal abrasion, better stress modulation through plastic deformation, and good color stability, which make it a promising alternative to zirconia crown.

Comparison of Accuracy of Current Ten Intraoral Scanners.

There have been various developments in intraoral 3D scanning technology. This study is aimed at investigating the accuracy of 10 scanners developed from 2015 to 2020. A maxillary dental model with reference points was printed from Form 2 (FormLabs, Somerville, MA, USA). The model was scanned 5 times with each intraoral scanner (IOS); Trios 3 (normal and high-resolution mode); Trios 4 (normal and high-resolution mode) (3Shape Trios A/S, Copenhagen, Denmark); iTero Element, iTero 2, and iTero 5D Element (Align Technologies, San Jose, California, USA); Dental Wings (Dental Wings, Montreal QC, Canada); Panda 2 (Pengtum Technologies, Shanghai, China); Medit i500 (Medit Corp. Seoul, South Korea); Planmeca Emerald™ (Planmeca, Helsinki, Finland); and Aoralscan (Shining 3D Tech. Co., Ltd., Hangzhou, China). After the scan, the 3D scanned stereolithography files were created. The various distances were measured five times in X, Y, Z, and XY axes of various scans and with a vernier caliper (control) and from the Rhinoceros software. The data were analyzed using SPSS 18. Test for the normality of the various measurement data were done using Kolmogorov-Smirnov test. The trueness and precision of the measurements were compared among the various scans using the Kruskal-Wallis test. The significance was considered at P < 0.05. The trueness of the intraoral scans was analyzed by comparing the measurements from the control. Precision was tested through the measurements of repeated scans. It showed that more the distance is less the accuracy for all scanners. In all studied scanners, the trueness varied but precision was favorably similar. Diagonal scanning showed less accuracy for all the scanners. Hence, when scanning the full arch, the dentist needs to take more caution and good scan pattern. Trios series showed the best scan results compared to other scanners.

Studying the Optical 3D Accuracy of Intraoral Scans: An In Vitro Study.

There are various scanners available in dental practice with various accuracies. The aim of this study was to compare the 3D capturing accuracy of scans obtained from Trios 3 and Dental Wings scanner. A reference mandibular model was printed from FormLab with reference points in three axes (X, Y, and XY and Z). The printed model was scanned 5 times with 3 scans: normal scan by Trios 3 (Trios 3A), high-resolution scan by Trios 3 (Trios 3B), and normal scan by Dental Wings. After scan, the stereolithography (stl) files were generated. Then, the measurements were made from the computer software using Rhinoceros 3D (Rhino, Robert McNeel & Associates for Windows, Washington DC, USA). The measurements made with digital caliper were taken as control. Statistical analysis was done using one-way ANOVA with post hoc using Sheffe (P < 0.01). Trios 3 presented higher accuracy than Dental Wings and high resolution showed better results. The Dental Wings showed less accuracy at the measurements >50 mm of length and >30 mm in width. There was no significant difference (P > 0.05) of control with the Trios 3A and Trios 3B. Similarly, for the measurements in Z-axis, there was no significant difference of control with each scan (Trios 3A, Trios 3B, and Dental Wings). Accuracy of the scan is affected by the length of the scanning area and scanning pattern. It is less recommended to Dental Wings scan >3-unit prosthesis and that crosses the midline.

The Accuracy of Digital Face Scans Obtained from 3D Scanners: An In Vitro Study.

Face scanners promise wide applications in medicine and dentistry, including facial recognition, capturing facial emotions, facial cosmetic planning and surgery, and maxillofacial rehabilitation. Higher accuracy improves the quality of the data recorded from the face scanner, which ultimately, will improve the outcome. Although there are various face scanners available on the market, there is no evidence of a suitable face scanner for practical applications. The aim of this in vitro study was to analyze the face scans obtained from four scanners; EinScan Pro (EP), EinScan Pro 2X Plus (EP+) (Shining 3D Tech. Co., Ltd. Hangzhou, China), iPhone X (IPX) (Apple Store, Cupertino, CA, USA), and Planmeca ProMax 3D Mid (PM) (Planmeca USA, Inc. IL, USA), and to compare scans obtained from various scanners with the control (measured from Vernier caliper). This should help to identify the appropriate scanner for face scanning. A master face model was created and printed from polylactic acid using the resolution of 200 microns on x, y, and z axes and designed in Rhinoceros 3D modeling software (Rhino, Robert McNeel and Associates for Windows, Washington DC, USA). The face models were 3D scanned with four scanners, five times, according to the manufacturer's recommendations; EinScan Pro (Shining 3D Tech. Co., Ltd. Hangzhou, China), EinScan Pro 2X Plus (Shining 3D Tech. Co., Ltd. Hangzhou, China) using Shining Software, iPhone X (Apple Store, Cupertino, CA, USA) using Bellus3D Face Application (Bellus3D, version 1.6.2, Bellus3D, Inc. Campbell, CA, USA), and Planmeca ProMax 3D Mid (PM) (Planmeca USA, Inc. IL, USA). Scan data files were saved as stereolithography (STL) files for the measurements. From the STL files, digital face models are created in the computer using Rhinoceros 3D modeling software (Rhino, Robert McNeel and Associates for Windows, Washington DC, USA). Various measurements were measured five times from the reference points in three axes (x, y, and z) using a digital Vernier caliper (VC) (Mitutoyo 150 mm Digital Caliper, Mitutoyo Co., Kanagawa, Japan), and the mean was calculated, which was used as the control. Measurements were measured on the digital face models of EP, EP+, IPX, and PM using Rhinoceros 3D modeling software (Rhino, Robert McNeel and Associates for Windows, Washington DC, USA). The descriptive statistics were done from SPSS version 20 (IBM Company, Chicago, USA). One-way ANOVA with post hoc using Scheffe was done to analyze the differences between the control and the scans (EP, EP+, IPX, and PM). The significance level was set at p = 0.05. EP+ showed the highest accuracy. EP showed medium accuracy and some lesser accuracy (accurate until 10 mm of length), but IPX and PM showed the least accuracy. EP+ showed accuracy in measuring the 2 mm of depth (diameter 6 mm). All other scanners (EP, IPX, and PM) showed less accuracy in measuring depth. Finally, the accuracy of an optical scan is dependent on the technology used by each scanner. It is recommended to use EP+ for face scanning.

Maxillary Anterior Teeth Proportions for Creating Esthetically Pleasuring Smile in Nepalese Patients.

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Rapid fabrication of a digital prosthesis.

Finger prosthesis often needs refabrication due to its discoloration following use. This article presents a novel, economical, and cost-effective technique to duplicate the patient׳s existing prosthesis to obtain a new wax replica, which is then clinically tried and processed to obtain new silicone finger prosthesis. This technique requires comparatively less clinical and laboratory steps as to fabricate an entirely new prosthesis. The newly fabricated silicone finger prosthesis has the fit and marginal adaptation of the patient׳s existing prosthesis but the esthetics is improved.

Assistance of pressure conformer for reconstruction of lower fornix.

Absence of fornix in anopthalmic socket can result in difficulty in prosthetic and cosmetic rehabilitation. A 30-year-old female was presented with absence of the lower fornix in anopthalmic socket. A stock conformer was used to create continuous downward pressure with the help of an acrylic rod, gauze and a medical adhesive tape. Eventually, a lower fornix was created and finally rehabilitated with ocular prosthesis.

Lemongrass-Incorporated Tissue Conditioner Against Candida albicans Culture.

BACKGROUND: Tissue conditioner is applied popularly with dental prosthesis during wound healing process but it becomes a reservoir of oral microbiota, especially Candida species after long-term usage. Several antifungal drugs have been mixed with this material to control fungal level. In this study, lemongrass essential oil was added into COE-COMFORT tissue conditioner before being determined for anti-Candida efficacy. MATERIALS AND METHODS: Lemongrass (Cymbopogon citratus) essential oil was primarily determined for antifungal activity against C. albicans American type culture collection (ATCC) 10231 and MIC (minimum inhibitory concentration) value by agar disk diffusion and broth microdilution methods, respectively. COE-COMFORT tissue conditioner was prepared as recommended by the manufacturer after a fixed volume of the oil at its MIC or higher concentrations were mixed thoroughly in its liquid part. Antifungal efficacy of the tissue conditioner with/without herb was finally analyzed. RESULTS: Lemongrass essential oil displayed potent antifungal activity against C. albicans ATCC 10231and its MIC value was 0.06% (v/v). Dissimilarly, the tissue conditioner containing the oil at MIC level did not cease the growth of the tested fungus. Both reference and clinical isolates of C. albicans were completely inhibited after exposed to the tissue conditioner containing at least 0.25% (v/v) of the oil (approximately 4-time MIC). The tissue conditioner without herb or with nystatin was employed as negative or positive control, respectively. CONCLUSION: COE-COMFORT tissue conditioner supplemented with lemongrass essential oil obviously demonstrated another desirable property as in vitro anti-Candida efficacy to minimize the risk of getting Candidal infection.

Prosthetic rehabilitation of an ocular defect with post-enucleation socket syndrome: A case report.

Ocular trauma can be caused by road traffic accidents, falls, assaults, or work-related accidents. Enucleation is often indicated after ocular injury or for the treatment of intraocular tumors, severe ocular infections, and painful blind eyes. Rehabilitation of an enucleated socket without an intraocular implant or with an inappropriately sized implant can result in superior sulcus deepening, enophthalmos, ptosis, ectropion, and lower lid laxity, which are collectively known as post-enucleation socket syndrome. This clinical report describes the rehabilitation of post-enucleation socket syndrome with a modified ocular prosthesis. Modifications to the ocular prosthesis were performed to correct the ptosis, superior sulcus deepening, and enophthalmos. The rehabilitation procedure produced satisfactory results.

One- vs two stage surgery technique for implant placement in finger prosthesis.

BACKGROUND: The loss of the finger can lead to psychological problems. Although several reconstructive techniques may exist, the use of osseous-integrated implants to anchor digital prosthesis presents a suitable alternative for the amputation of finger. The surgery for implant placement has initially been described as a two-stage technique. However, no study in the literature has attempted to compare this technique with one-stage technique and stated a clear superiority technique in the implant retained finger prosthesis. METHODS: This article describes two cases of digital amputation as a result of accident; a 45-year-old female whose second finger of right hand was lost and a 25-year-old male patient with amputation of the first finger of right hand. RESULT AND CONCLUSION: One-stage implant placement technique for implant retained finger prosthesis is a reliable, safe and efficient option that allows a good result in a significantly lower operating time and hospital visits compared to the two-stage technique. It could therefore, be considered as good option for implant retained finger prosthesis.

Stress distribution in implant retained finger prosthesis: a finite element study.

BACKGROUND: Finger amputation may result from congenital cause, trauma, infection and tumours. The finger amputation may be rehabilitated with dental implant-retained finger prosthesis. The success of implant-retained finger prosthesis is determined by the implant loading. The type of the force is a determining factor in implant loading. OBJECTIVE: To evaluate stress distributions in finger bone when the loading force is applied along the long axis of the implant using finite element analysis. METHOD: The finite element models were created. The finger bone model containing cortical bone and cancellous bone was constructed by using radiograph. Astra Tech Osseo Speed bone level implant of 4.5 mm diameter and 14 mm length was selected. The force was applied to the top of the abutment along the long axis of the implant. RESULTS: Finite element analysis indicated that the maximum stress was located at the head of abutment screw. The minimum stress was located in the apical third of the implant fixture. The weakest point was calculated by safety factor which is located in the spongy bone at apical third of the fixtures. Finally, 4.9 times yield stress of spongy bone was needed for the deformation of the spongy bone. CONCLUSION: Finite element study showed that when the force was applied along the long axis of the implant, the maximum stress was located around the neck of the implant and the cortex bone received more stress than cancellous bone. So, to achieve long term success, the designers of implant systems must confront biomaterial and biomechanical problems including in vivo forces on implants, load transmission to the interface and interfacial tissue response.