Displaying publications 21 - 40 of 68 in total

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  1. Farook TH, Barman A, Abdullah JY, Jamayet NB
    J Prosthodont, 2021 Jun;30(5):420-429.
    PMID: 33200429 DOI: 10.1111/jopr.13286
    PURPOSE: Mesh optimization reduces the texture quality of 3D models in order to reduce storage file size and computational load on a personal computer. This study aims to explore mesh optimization using open source (free) software in the context of prosthodontic application.

    MATERIALS AND METHODS: An auricular prosthesis, a complete denture, and anterior and posterior crowns were constructed using conventional methods and laser scanned to create computerized 3D meshes. The meshes were optimized independently by four computer-aided design software (Meshmixer, Meshlab, Blender, and SculptGL) to 100%, 90%, 75%, 50%, and 25% levels of original file size. Upon optimization, the following parameters were virtually evaluated and compared; mesh vertices, file size, mesh surface area (SA), mesh volume (V), interpoint discrepancies (geometric similarity based on virtual point overlapping), and spatial similarity (volumetric similarity based on shape overlapping). The influence of software and optimization on surface area and volume of each prosthesis was evaluated independently using multiple linear regression.

    RESULTS: There were clear observable differences in vertices, file size, surface area, and volume. The choice of software significantly influenced the overall virtual parameters of auricular prosthesis [SA: F(4,15) = 12.93, R2 = 0.67, p < 0.001. V: F(4,15) = 9.33, R2 = 0.64, p < 0.001] and complete denture [SA: F(4,15) = 10.81, R2 = 0.67, p < 0.001. V: F(4,15) = 3.50, R2 = 0.34, p = 0.030] across optimization levels. Interpoint discrepancies were however limited to <0.1mm and volumetric similarity was >97%.

    CONCLUSION: Open-source mesh optimization of smaller dental prostheses in this study produced minimal loss of geometric and volumetric details. SculptGL models were most influenced by the amount of optimization performed.

    Matched MeSH terms: Computer-Aided Design
  2. Hassan LA, Goo CL
    Dent Mater J, 2021 Sep 30;40(5):1189-1195.
    PMID: 34078778 DOI: 10.4012/dmj.2020-408
    This research aimed to evaluate the effect of cement space on the marginal discrepancy and retention of computer-aided design/computer-aided manufacturing (CAD/CAM) crowns. A total of 30 premolar Frasaco teeth were machined to receive crowns with cement spaces of 70, 90, and 110 μm. The marginal discrepancy measurements were done before and after cementation. Pull-off test was conducted using universal testing machine (UTM). Data was analyzed using two-way mixed ANOVA with post-hoc Bonferroni test and Kruskal-Wallis test. The crowns with cement space of 70 μm showed a significantly higher absolute marginal discrepancy than those with 90 and 110 μm. No significant effect on the crown retention was found. Within the limitations of this study, modifying cement space to 90 μm and 110 μm may improve the marginal adaptation of CAD/CAM crown, whereas adjusting cement space from 70 to 110 μm did not significantly affect the crown retention.
    Matched MeSH terms: Computer-Aided Design
  3. Goo CL, Tan KB
    Case Rep Dent, 2017;2017:9373818.
    PMID: 28396807 DOI: 10.1155/2017/9373818
    This report describes the clinical and technical aspects in the oral rehabilitation of an edentulous patient with knife-edge ridge at the mandibular anterior edentulous region, using implant-retained overdentures. The application of computer-aided design and computer-aided manufacturing (CAD/CAM) in the fabrication of the overdenture framework simplifies the laboratory process of the implant prostheses. The Nobel Procera CAD/CAM System was utilised to produce a lightweight titanium overdenture bar with locator attachments. It is proposed that the digital workflow of CAD/CAM milled implant overdenture bar allows us to avoid numerous technical steps and possibility of casting errors involved in the conventional casting of such bars.
    Matched MeSH terms: Computer-Aided Design
  4. Berhanuddin Muhamad Asyraf, Tong, Wah Lim
    Malaysian Dental Journal, 2016;2016(2):0-0.
    MyJurnal
    In nowadays world, aesthetic dentistry has becoming a trend with the improvement of dental technology and materials. Composite resin becomes the material of choice as it offers good aesthetics, longevity and allow for minimally intervention approach. There are various ways of composite restorative techniques recommended to make out the best restorative outcome. Direct restorative technique promise acceptable cost, appointment time and color matching but it is a challenge for the clinician especially for extensive cavities. Indirect technique is good for extended cavity and providing less operator error, however, it requires multiple appointments, higher cost and laboratory involvement. Computer-aided design/ computer-aided manufacturing (CAD/CAM) technology might reduce the number of appointments, however, it will cause more financial burden to the patient and the clinician. Therefore, semi-direct technique was introduced, it combines the benefits of direct and indirect technique and this technique can be done without the use of any advanced technology and give out a good treatment outcome.
    Matched MeSH terms: Computer-Aided Design
  5. Farook TH, Rashid F, Jamayet NB, Abdullah JY, Dudley J, Khursheed Alam M
    J Prosthet Dent, 2022 Oct;128(4):830-836.
    PMID: 33642077 DOI: 10.1016/j.prosdent.2020.12.041
    STATEMENT OF PROBLEM: The anatomic complexity of the ear challenges conventional maxillofacial prosthetic rehabilitation. The introduction of specialized scanning hardware integrated into computer-aided design and computer-aided manufacturing (CAD-CAM) workflows has mitigated these challenges. Currently, the scanning hardware required for digital data acquisition is expensive and not readily available for prosthodontists in developing regions.

    PURPOSE: The purpose of this virtual analysis study was to compare the accuracy and precision of 3-dimensional (3D) ear models generated by scanning gypsum casts with a smartphone camera and a desktop laser scanner.

    MATERIAL AND METHODS: Six ear casts were fabricated from green dental gypsum and scanned with a laser scanner. The resultant 3D models were exported as standard tessellation language (STL) files. A stereophotogrammetry system was fabricated by using a motorized turntable and an automated microcontroller photograph capturing interface. A total of 48 images were captured from 2 angles on the arc (20 degrees and 40 degrees from the base of the turntable) with an image overlap of 15 degrees, controlled by a stepper motor. Ear 1 was placed on the turntable and captured 5 times with smartphone 1 and tested for precision. Then, ears 1 to 6 were scanned once with a laser scanner and with smartphones 1 and 2. The images were converted into 3D casts and compared for accuracy against their laser scanned counterparts for surface area, volume, interpoint mismatches, and spatial overlap. Acceptability thresholds were set at <0.5 mm for interpoint mismatches and >0.70 for spatial overlap.

    RESULTS: The test for smartphone precision in comparison with that of the laser scanner showed a difference in surface area of 774.22 ±295.27 mm2 (6.9% less area) and in volume of 4228.60 ±2276.89 mm3 (13.4% more volume). Both acceptability thresholds were also met. The test for accuracy among smartphones 1, 2, and the laser scanner showed no statistically significant differences (P>.05) in all 4 parameters among the groups while also meeting both acceptability thresholds.

    CONCLUSIONS: Smartphone cameras used to capture 48 overlapping gypsum cast ear images in a controlled environment generated 3D models parametrically similar to those produced by standard laser scanners.

    Matched MeSH terms: Computer-Aided Design
  6. Munusamy SM, Helen-Ng LC, Farook MS
    BMC Oral Health, 2024 Feb 01;24(1):162.
    PMID: 38302972 DOI: 10.1186/s12903-024-03905-7
    BACKGROUND: Computer-aided design/computer-aided manufacturing (CAD/CAM) dental composites were introduced with superior mechanical properties than conventional dental composites. However, little is known on effects of dietary solvents on microhardness or inorganic elemental composition of CAD/CAM composites.

    OBJECTIVES: The objectives of this study were to evaluate the degradation effects of each dietary solvent on the microhardness of the different CAD/CAM dental composites and to observe the degradation effects of dietary solvent on the inorganic elements of the dental composites investigated.

    METHODS: Fifty specimens with dimensions 12 mm x 14 mm x 1.5 mm were prepared for direct composite (Filtek Z350 XT [FZ]), indirect composite (Shofu Ceramage [CM]), and three CAD/CAM composites (Lava Ultimate [LU], Cerasmart [CS], and Vita Enamic [VE]). The specimens were randomly divided into 5 groups (n = 10) and conditioned for 1-week at 37°C in the following: air (control), distilled water, 0.02 N citric acid, 0.02 N lactic acid and 50% ethanol-water solution. Subsequently, the specimens were subjected to microhardness test (KHN) using Knoop hardness indenter. Air (control) and representative postconditioning specimens with the lowest mean KHN value for each material were analyzed using energy dispersive X-ray spectroscopy (EDX). Statistical analysis was done using one-way ANOVA and post hoc Bonferroni test at a significance level of p = 0.05.

    RESULTS: Mean KHN values ranged from 39.7 ± 2.7 kg/mm2 for FZ conditioned in 50% ethanol-water solution to 79.2 ± 3.4 kg/mm2 for VE conditioned in air (control). With exception to LU, significant differences were observed between materials and dietary solvents for other dental composites investigated. EDX showed stable peaks of the inorganic elements between air (control) and representative postconditioning specimens.

    CONCLUSIONS: The microhardness of dental composites was significantly affected by dietary solvents, except for one CAD/CAM composite [LU]. However, no changes were observed in the inorganic elemental composition of dental composites between air (control) and 1-week postconditioning.

    Matched MeSH terms: Computer-Aided Design
  7. Mutashar S, Hannan MA, Samad SA, Hussain A
    Sensors (Basel), 2014;14(7):11522-41.
    PMID: 24984057 DOI: 10.3390/s140711522
    The use of wireless communication using inductive links to transfer data and power to implantable microsystems to stimulate and monitor nerves and muscles is increasing. This paper deals with the development of the theoretical analysis and optimization of an inductive link based on coupling and on spiral circular coil geometry. The coil dimensions offer 22 mm of mutual distance in air. However, at 6 mm of distance, the coils offer a power transmission efficiency of 80% in the optimum case and 73% in the worst case via low input impedance, whereas, transmission efficiency is 45% and 32%, respectively, via high input impedance. The simulations were performed in air and with two types of simulated human biological tissues such as dry and wet-skin using a depth of 6 mm. The performance results expound that the combined magnitude of the electric field components surrounding the external coil is approximately 98% of that in air, and for an internal coil, it is approximately 50%, respectively. It can be seen that the gain surrounding coils is almost constant and confirms the omnidirectional pattern associated with such loop antennas which reduces the effect of non-alignment between the two coils. The results also show that the specific absorption rate (SAR) and power loss within the tissue are lower than that of the standard level. Thus, the tissue will not be damaged anymore.
    Matched MeSH terms: Computer-Aided Design*
  8. Islam NN, Hannan MA, Shareef H, Mohamed A, Salam MA
    ScientificWorldJournal, 2014;2014:549094.
    PMID: 24977210 DOI: 10.1155/2014/549094
    Power oscillation damping controller is designed in linearized model with heuristic optimization techniques. Selection of the objective function is very crucial for damping controller design by optimization algorithms. In this research, comparative analysis has been carried out to evaluate the effectiveness of popular objective functions used in power system oscillation damping. Two-stage lead-lag damping controller by means of power system stabilizers is optimized using differential search algorithm for different objective functions. Linearized model simulations are performed to compare the dominant mode's performance and then the nonlinear model is continued to evaluate the damping performance over power system oscillations. All the simulations are conducted in two-area four-machine power system to bring a detailed analysis. Investigated results proved that multiobjective D-shaped function is an effective objective function in terms of moving unstable and lightly damped electromechanical modes into stable region. Thus, D-shape function ultimately improves overall system damping and concurrently enhances power system reliability.
    Matched MeSH terms: Computer-Aided Design*
  9. Naz MY, Shukrullah S, Ghaffar A, Rehman NU
    ScientificWorldJournal, 2014;2014:279868.
    PMID: 24683326 DOI: 10.1155/2014/279868
    Multitip probes are very useful diagnostics for analyzing and controlling the physical phenomena occurring in low temperature discharge plasmas. However, DC biased probes often fail to perform well in processing plasmas. The objective of the work was to deduce simple designs of DC biased multitip probes for parametric study of radio frequency plasmas. For this purpose, symmetric double probe, asymmetric double probe, and symmetric triple probe diagnostic systems and their driving circuits were designed and tested in an inductively coupled plasma (ICP) generated by a 13.56 MHz radio frequency (RF) source. Using I-V characteristics of these probes, electron temperature, electron number density, and ion saturation current was measured as a function of input power and filling gas pressure. An increasing trend was noticed in electron temperature and electron number density for increasing input RF power whilst a decreasing trend was evident in these parameters when measured against filling gas pressure. In addition, the electron energy probability function (EEPF) was also studied by using an asymmetric double probe. These studies confirmed the non-Maxwellian nature of the EEPF and the presence of two groups of the energetic electrons at low filling gas pressures.
    Matched MeSH terms: Computer-Aided Design*
  10. Yang HZ, Lim KS, Qiao XG, Chong WY, Cheong YK, Lim WH, et al.
    Opt Express, 2013 Jun 17;21(12):14808-15.
    PMID: 23787668 DOI: 10.1364/OE.21.014808
    We present a new theoretical model for the broadband reflection spectra of etched FBGs which includes the effects of axial contraction and stress-induced index change. The reflection spectra of the etched FBGs with several different taper profiles are simulated based on the proposed model. In our observation, decaying exponential profile produces a broadband reflection spectrum with good uniformity over the range of 1540-1560 nm. An etched FBG with similar taper profile is fabricated and the experimental result shows good agreement with the theoretical model.
    Matched MeSH terms: Computer-Aided Design*
  11. Al-Asadi HA, Abu Bakar MH, Al-Mansoori MH, Adikan FR, Mahdi MA
    Opt Express, 2011 Dec 5;19(25):25741-8.
    PMID: 22273966 DOI: 10.1364/OE.19.025741
    This paper details a theoretical modeling of Brillouin ring fiber laser which incorporates the interaction between multiple Brillouin Stokes signals. The ring cavity was pumped at several Brillouin pump (BP) powers and the output was measured through an optical coupler with various coupling ratios. The first-order Brillouin Stokes signal was saturated with the presence of the second-order Stokes signal in the cavity as a result of energy transfer between them. The outcome of the study found that the optimum point for the first-order Stokes wave performance is at laser power reduction of 10%. Resultantly, at the optimum output coupling ratio of 90%, the BFL was able to produce 19.2 mW output power at BP power and Brillouin threshold power of 60 and 21.3 mW respectively. The findings also exhibited the feasibility of the theoretical models application to ring-type Brillouin fiber laser of various design parameters.
    Matched MeSH terms: Computer-Aided Design*
  12. Baig MR, Tan KB, Nicholls JI
    J Prosthet Dent, 2010 Oct;104(4):216-27.
    PMID: 20875526 DOI: 10.1016/S0022-3913(10)60128-X
    The marginal fit of crowns is a concern for clinicians, and there is no conclusive evidence of any one margin configuration yielding better results than others in terms of marginal fit.
    Matched MeSH terms: Computer-Aided Design*
  13. Omar H, Atta O, El-Mowafy O, Khan SA
    J Dent, 2010;38 Suppl 2:e95-9.
    PMID: 20493232 DOI: 10.1016/j.jdent.2010.05.006
    To determine the effect of thickness of porcelain veneers constructed from CAD-CAM on their final color when two resin cements were used.
    Matched MeSH terms: Computer-Aided Design*
  14. Senthilpari C, Diwakar K, Singh AK
    Recent Pat Nanotechnol, 2009;3(1):61-72.
    PMID: 19149756
    The paper discuss the design of 1-bit full adder circuit using Shannon theorem. This proposed full adder circuit is used as one of the circuit component for implementation of Non- Restoring and Restoring divider circuits. The proposed adder and divider schematics are designed by using DSCH2 CAD tool and their layouts are generated by Microwind 3 VLSI CAD tool. The divider circuits are designed by using standard CMOS 0.35 microm feature size and corresponding power supply 3.5 V. The parameters analyses are carried out by BSIM 4 analysis. We have compared the simulated results of the Shannon based divider circuit with CPL and CMOS adder cell based divider circuits. We have further compared the results with published results and observed that the proposed adder cell based divider circuit dissipates lower power, gives faster response, lower latency, low EPI and high throughput.
    Matched MeSH terms: Computer-Aided Design*
  15. Lambak Z, Abdul Rahman F, Mokhtar MR, Tengku IA
    Opt Express, 2009 Feb 16;17(4):2926-37.
    PMID: 19219196
    The method of lines (MoL) has been developed to study coupling efficiency on hemispherical lens. In this paper, the physical shape of the lens is approximated by cascading a number of straight waveguide segments. The perfectly matched layer (PML) is applied as an absorber for the MoL to reduce numerical reflection in the simulation region. Analysis is done by calculating coupling efficiency at the plane of integration where the coupling efficiency is an overlap integral between laser diode field and fiber field. The result of coupling efficiency in this analysis is compared to the experiment and ABCD matrix. It is found that MoL gives good result accuracy.
    Matched MeSH terms: Computer-Aided Design*
  16. Al-Mansoori MH, Mahdi MA
    Opt Express, 2008 May 26;16(11):7649-54.
    PMID: 18545472
    We demonstrate an enhanced multiwavelength L-band Brillouin-erbium fiber laser (BEFL), in which the Brillouin pump is pre-amplified before entering the single-mode fiber. The Brillouin pump pre-amplification provided by the Erbium-doped fiber has created higher intensity of Brillouin Stokes line generated in the single-mode fiber that leads to the homogenous gain saturation. Thus the built-up of self-lasing cavity modes is suppressed in a wider wavelength range. In contrary to the conventional linear-cavity BEFL, the number of output channels is enhanced within the same tuning range.
    Matched MeSH terms: Computer-Aided Design*
  17. Ahmed N, Abbasi MS, Haider S, Ahmed N, Habib SR, Altamash S, et al.
    Biomed Res Int, 2021;2021:3194433.
    PMID: 34532499 DOI: 10.1155/2021/3194433
    Objective: Analyzing and comparing the fit and accuracy of removable partial denture (RPDs) frameworks fabricated with CAD/CAM and rapid prototyping methods with conventional techniques.

    Materials and Methods: The present systematic review was carried out according to PRISMA guidelines. The search was carried out on PubMed/MEDLINE, Cochrane collaboration, Science direct, and Scopus scientific engines using selected MeSH keywords. The articles fulfilling the predefined selection criteria based on the fit and accuracy of removable partial denture (RPD) frameworks constructed from digital workflow (CAD/CAM; rapid prototyping) and conventional techniques were included.

    Results: Nine full-text articles comprising 6 in vitro and 3 in vivo studies were included in this review. The digital RPDs were fabricated in all articles by CAD/CAM selective laser sintering and selective laser melting techniques. The articles that have used CAD/CAM and rapid prototyping technique demonstrated better fit and accuracy as compared to the RPDs fabricated through conventional techniques. The least gaps between the framework and cast (41.677 ± 15.546 μm) were found in RPDs constructed through digital CAD/CAM systems.

    Conclusion: A better accuracy was achieved using CAD/CAM and rapid prototyping techniques. The RPD frameworks fabricated by CAD/CAM and rapid prototyping techniques had clinically acceptable fit, superior precision, and better accuracy than conventionally fabricated RPD frameworks.

    Matched MeSH terms: Computer-Aided Design/trends
  18. Choong YS, Lee YV, Soong JX, Law CT, Lim YY
    Adv Exp Med Biol, 2017;1053:221-243.
    PMID: 29549642 DOI: 10.1007/978-3-319-72077-7_11
    The use of monoclonal antibody as the next generation protein therapeutics with remarkable success has surged the development of antibody engineering to design molecules for optimizing affinity, better efficacy, greater safety and therapeutic function. Therefore, computational methods have become increasingly important to generate hypotheses, interpret and guide experimental works. In this chapter, we discussed the overall antibody design by computational approches.
    Matched MeSH terms: Computer-Aided Design*
  19. Al-Asadi HA, Al-Mansoori MH, Hitam S, Saripan MI, Mahdi MA
    Opt Express, 2011 Jan 31;19(3):1842-53.
    PMID: 21368999 DOI: 10.1364/OE.19.001842
    We implement a particle swarm optimization (PSO) algorithm to characterize stimulated Brillouin scattering phenomena in optical fibers. The explicit and strong dependence of the threshold exponential gain on the numerical aperture, the pump laser wavelength and the optical loss coefficient are presented. The proposed PSO model is also evaluated with the localized, nonfluctuating source model and the distributed (non-localized) fluctuating source model. Using our model, for fiber lengths from 1 km to 29 km, the calculated threshold exponential gain of stimulated Brillouin scattering is gradually decreased from 17.4 to 14.6 respectively. The theoretical results of Brillouin threshold power predicted by the proposed PSO model show a good agreement with the experimental results for different fiber lengths from 1 km to 12 km.
    Matched MeSH terms: Computer-Aided Design
  20. Mahdi MA, Sheih SJ, Adikan FR
    Opt Express, 2009 Jun 08;17(12):10069-75.
    PMID: 19506658
    We demonstrate a simplified algorithm to manifest the contribution of amplified spontaneous emission in variable gain-flattened Erbium-doped fiber amplifier (EDFA). The detected signal power at the input and output ports of EDFA comprises of both signal and noise. The generated amplified spontaneous emission from EDFA cannot be differentiated by photodetector which leads to underestimation of the targeted gain value. This gain penalty must be taken into consideration in order to obtain the accurate gain level. By taking the average gain penalty within the dynamic gain range, the targeted output power is set higher than the desired level. Thus, the errors are significantly reduced to less than 0.15 dB from 15 dB to 30 dB desired gain values.
    Matched MeSH terms: Computer-Aided Design
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