Computer-assisted Design/computer-assisted Manufacturing Research Articles

Orthodontics Simulations as Teaching Tools

Traditional teaching methods in orthodontics employ static photos posing immense challenges as the learner is unable to conceptualise the changes in different planes that affect final tooth positions in the upper and lower jaws following treatment. Furthermore, the protracted treatment time of orthodontics ranges from 12 months (simple cases) to 36 months (complex cases) thus adding yet another dimension “patient growth” especially children often referred to as 4th Dimension of Time. Previous work at UQ with SBLi (Scenario Based Learning interactive https://youtu.be/PUIanIl5CFc?si=vDf8JwFjHixtzol7) (Naser-ud-Din, 2015) has shown that creating online teaching tools incorporating multimedia to address the concepts of dynamic change and is impactful for student learning on demand with global accessibility. Online asynchronous learning have three key strengths: firstly, flexibility for updating with contemporary software by learning designers and academics; secondly, ease for formative assessment for large cohorts and thirdly, international presence for potential commercialization. Feedback at UQ for postgraduate orthodontic students was overwhelmingly positive as students found interactivity highly engaging and appreciated the self-regulated aspect of it akin to that found in other publications (Hakami, 2021; Khoo et al., 2023; Naser-ud-Din, 2016). However, simulation creation is expensive (Kröger et al., 2017) and thus, it is essential to explore cost-effective teaching tools that are sustainable with the dental industry partners and easily translated into clinical practice. With advent of 3D simulations in Orthodontics, current literature is limited (Ho et al., 2022; Karanth et al., 2024; Sipiyaruk et al., 2023) and future best practices will require initiatives to enhance teaching recommendations. Moreover, LEAN an essential component for success in major industries who observer consistent success such as in aviation, and other professions have added value of efficiency, effectiveness, convenience and comfort. Hallmarks to improve outcomes and safety. The aim of this project is to complete 5 essential orthodontic chapters for the Doctor of Dental Surgery (DDS) students at MDS in (years 2-4) by introducing 3D simulations for orthodontic treatments start to finish; embedded in H5P teaching assessment tool. At present, limited number of such modules have been created with original clinical cases by the primary investigator (SN). Interactive online digital assets are valuable and need to be based on sound principles of Heutagogy for self-directed learning. Furthermore, LEAN foundation creates effectiveness and efficiency of delivery of core content. Essentially this project is aligned with Advancing students education strategy 2023-30 of the UoM P-9 “remove barriers to innovation and forge new partnership models between professional and academic”. At the time of writing there is lack of integrated 3D simulations for education in Orthodontics, thus addressing a gap to create interactive learning environments that are translated to clinical practice in dentistry. Thus utilizing in future CADCAM (Computer assisted Design Computer Assisted Manufacture) with efficiency and confidence for the graduate learner. The CADCAM tech is now widely incorporated by industry partners in dental technologies into mainstream Dentistry providing precision and speed. Refinement of these three modules will pave way as huge potential for commercialization under the banner of UoM with InnovateEd in near future. Moreover, the LEAN will assist in providing future sustainability.

Effect of different beverages and polishing techniques on colour stability of CAD/CAM composite restorative materials.

The aim of this article was to compare the colour stability of short fibre-reinforced computer-assisted design/computer-assisted manufacturing (CAD/CAM) composite (SFRC CAD) to commercially available CAD/CAM materials following prolonged immersion in a variety of beverages. Furthermore, the influence of the polishing technique was evaluated. A total of 120 rectangular specimens (10 mm length × 14 mm width × 2 mm thickness) were prepared from SFRC CAD, IPS e-max, Cerasmart 270, Celtra Duo, Enamic, and Brilliant Crios. The specimens underwent polishing through either a laboratory polishing machine equipped with 4000-grit silicon carbide paper or chairside polishing using Sof-Lex spiral. Twenty specimens of each tested CAD/CAM material were randomly divided into four groups (n = 5) based on the staining solution used in order to evaluate the colour stability of the materials. Group 1: distilled water, Group 2: coffee, Group 3: red wine, Group 4: coke. Using a spectrophotometer, the colour changes (∆E) of all CAD/CAM materials were assessed at baseline, and after 1 and 12 weeks of staining. Three-way analysis of variance was used to analyse the data (α = 0.05). The staining solution and material type showed a significant influence on the CAD/CAM specimens' colour stability (p < 0.05), while polishing method had no significant influence (p > 0.05). The average ∆E values for specimens submerged in wine were considerably higher (p < 0.05) than those for the other solutions. SFRC CAD, Cerasmart 270, and Enamic displayed the highest ∆E values in wine (p < 0.05). The colour stability of tested SFRC CAD was comparable to other composite-based CAD/CAM materials, while IPS e.max exhibited the highest level of colour stability.

Escherichia coli Cellular Activity and Frontal Trizonal Evaluation of Microspace Between Implants and Abutments Under Calibrated Cyclic Stress.

To evaluate microspace and microleakage between implant and abutments subjected to pre- and post-calibrated cyclic stress. Twelve screw-retained implant prostheses with BioHPP polyetheretherketone (PEEK) abutment (Noris Dental Implant System Ltd.,Nesher, Israel) (Group I) and 12 screw-retained implant prostheses with computer-assisted design/computer-assisted manufacturing (CAD/CAM) milled zirconia abutment (DentGallop, Houston, TX, USA) (Group II) were connected to their respective implant, and the prosthetic screw was torqued to 30N/cm (Noris). The microspace was evaluated using scanning electron microscopy (SEM; TeScan, Brno, Czech Republic). Twenty-four samples were then induced to cyclic stress (Lokesh Industries, Pune, India) simulating 180 days duration of oral stress. The microspaces (Group IA and Group IIB) were measured post-cyclic stress. Group I and II were again renamed into Group Ia and Group IIb for microbial study. Both implant assemblies were immersed in fresh soybean casein digest broth (SCDB) (Himedia, Mumbai, India) and subsequently inoculated with 1.0µL E. coli suspension (Himedia) at the open end and incubated at 37ºC for seven days. After the incubation period, cellular activity was determined by the spread plate method, and total colony-forming units (CFU) were calculated. The results were evaluated using independent Tand Mann-Whitney tests. Average and microspace at the implant-abutment junction of Group I samples in the front right was 12.98µm, center 13.76µm, front left 13.22µm, and in Group II samples, the front right was 18.52µm, center 17.84µm, front left 18.58µm.After being subjected to cyclic loading, the mean levels of the vertical microgap for Group IA samples were: in the front right region 10.37µm, in the center 9.34µm, in the front left 10.51µm and in Group IIB samples front right was 14.59µm, center 13.39µm, front left 13.8µm. Independent t-tests showed insignificant differences between the two groups. The median value of microbial leakage of Group Ia samples after cyclic loading was 30 x 103 CFU/ml, and Group IIb samples were 42 x 103 CFU/ml and were significant. There was minimal variation in the mean microspace between the BioHPP PEEK abutment and CAD/CAM milled zirconia abutment, and it was insignificant before and after cyclic stress. BioHPP PEEK abutment-titanium implant interfaces showed significantly decreased microbial leakage than CAD/CAM milled zirconia abutment-titanium implant interfaces after cyclic stress.

Surface Evaluation of Resilient CAD/CAM ceramics after Contouring and Polishing.

This in-vitro study measured the differences in surface roughness for computer assisted design/computer assisted manufacturing (CAD/CAM) resilient ceramic and CAD/CAM composite materials. The materials included Lava Ultimate (3 M), Cerasmart (GC America), Vita Enamic (Vita Zahnfabrik), and Brilliant Crios (Coltene). One calibrated operator polished each material with three polishing sytems: spiral polishers (Diacomp FeatherLite/Brasseler), rubbercup polishers (Enhance/DentsplyCaulk), and brush-paste (Diashine/VH Technologies). Surface roughness was assessed using a confocal laser microscope (Lext OLS4000/Olympus). A two-way ANOVA revealed statistically significant differences in mean surface roughness values (Sa) among materials and polishers. Tukey multiple comparisons showed that mean Sa values for Lava Ultimate, Enamic, Cerasmart and Brilliant Crios polished with brush-paste as well as Lava Ultimate and Cerasmart values polished with spiral polishers were not significantly different from each other. The finished surfaces were significantly smoother than milled surfaces for all materials. The brush-paste polishing technique created the lowest surface roughness values for all CAD/CAM materials and values were comparable to what was achieved by spiral polishers for Lava Ultimate and Cerasmart. Rubber polishers did not provide a clinically smooth surface for CAD/CAM resilient ceramic/composite materials. The results of the study indicate that polishing creates smooth surfaces for CAD/CAM resilient ceramic and CAD/CAM composite restorations.

Digital workflow coupling conic retention for the immediate restoration of adjacent posterior implants

To evaluate the digital workflow coupling conic retention for the immediate restoration of adjacent posterior implants. The patients with adjacent teeth missing in the posterior jaw seeking for implant restoration in the Department of Implantology, Peking University School and Hospital of Stomatology from March, 2017 to February, 2018 were recruited. After implant placement and commercial conic retention coping delivery, the patient had an intraoral scan for digital impression, and the computer-assisted design/computer-assisted manufacturing (CAD/CAM) technology was used for the fabrication of the immediate splinted prosthesis, which was made of polymethyl methacrylate (PMMA) and loaded immediately after delivery. Six months later, all the temporary prostheses were replaced by the permanent ones made of monolithic zirconia with CAD/CAM technology as well. The parallel periapical films were taken for the temporary and permanent prostheses post-delivery. The clinical effect of this workflow was evaluated by indices including the survival rates of implants and prostheses, the change of marginal bone level, and the implant-related and prosthesis-related complications; before the final restoration, the Visual Analogue Score (VAS) was used to evaluate the satisfaction of the patients. Ten patients (4 males and 6 females, 55.5 years old for average) were recruited. Totally 34 implants were placed; 14 prostheses were fabricated, temporary and permanent, respectively. After an observation period from 4 to 14 months, the survival rate for implants and prostheses were both 100%; the marginal bone level of the implants were (1.06±0.97) mm and (0.96±0.82) mm, immediate post-operation and 6 months later, respectively. The difference was not statistically significant (P>0.05). Neither implant- nor prostheses- related complications were observed. And the VAS of the patients' satisfaction was 87.2. For the adjacent posterior implants, the immediate prostheses manufactured by digital workflow, coupling conic retention, were clinically feasible and patient-satisfactory.

Lean Methods Applied to CAD/CAM Pedagogy in the Dental Simulation Laboratory.

Dental education is incorporating computer-assisted design/computer-assisted manufacturing (CAD/CAM) into patient care delivery. The aim of this study was to determine if lean production methods applied to the preclinical phase of dental education would reduce the students' time (efficiency) to complete CAD/CAM indirect restorations (CAD/CAM IR) without compromising the desired quality of the CAD/CAM tooth preparations (effectiveness). In 2016, all third-year students at one U.S. dental school were randomly assigned to control and research groups (approximately 33 per group). The control group was taught using existing methods, while the course was redesigned to incorporate lean methods for the research group. Cycle times of the CAD/CAM IR process for both groups were collected and statistically analyzed to compare the effectiveness of the redesign. Standardized grading forms and tools were used to assess the quality of the CAD/CAM tooth preparations. The research group demonstrated significantly faster preparation times with both crowns and onlays (p<0.05) than the control group. The research group also produced CAD/CAM crown and onlay designs at a significantly faster pace than the control group (p<0.05). There was no significant difference between the control and research groups associated with the scanning process times (p>0.05) nor in the quality of the CAD/CAM tooth preparations (p>0.05). This study demonstrated that lean methods applied to pedagogy significantly decreased preparation and design times in a CAD/CAM restorative dentistry course without compromising the quality of the CAD/CAM tooth preparations.

Combining Intraoral and Face Scans for the Design and Fabrication of Computer-Assisted Design/Computer-Assisted Manufacturing (CAD/CAM) Polyether-Ether-Ketone (PEEK) Implant-Supported Bars for Maxillary Overdentures.

Purpose To present a digital method that combines intraoral and face scanning for the computer-assisted design/computer-assisted manufacturing (CAD/CAM) fabrication of implant-supported bars for maxillary overdentures. Methods Over a 2-year period, all patients presenting to a private dental clinic with a removable complete denture in the maxilla, seeking rehabilitation with implants, were considered for inclusion in this study. Inclusion criteria were fully edentulous maxilla, functional problems with the preexisting denture, opposing dentition, and sufficient bone volume to insert four implants. Exclusion criteria were age < 55 years, need for bone augmentation, uncompensated diabetes mellitus, immunocompromised status, radio- and/or chemotherapy, and previous treatment with oral and/or intravenous aminobisphosphonates. All patients were rehabilitated with a maxillary overdenture supported by a CAD/CAM polyether-ether-ketone (PEEK) implant-supported bar. The outcomes of the study were the passive fit/adaptation of the bar, the 1-year implant survival, and the success rates of the implant-supported overdentures. Results 15 patients (6 males, 9 females; mean age 68.8 ± 4.7 years) received 60 implants and were rehabilitated with a maxillary overdenture supported by a PEEK bar, designed and milled from an intraoral digital impression. The intraoral scans were integrated with face scans, in order to design each bar with all available patient data (soft tissues, prosthesis, implants, and face) in the correct spatial position. When testing the 3D-printed resin bar, 12 bars out of 15 (80%) had a perfect passive adaptation and fit; in contrast, 3 out of 15 (20%) did not have a sufficient passive fit or adaptation. No implants were lost, for a 1-year survival of 100% (60/60 surviving implants). However, some complications (two fixtures with peri-implantitis in the same patient and two repaired overdentures in two different patients) occurred. This determined a 1-year success rate of 80% for the implant-supported overdenture. Conclusions In this study, the combination of intraoral and face scans allowed to successfully restore fully edentulous patients with maxillary overdentures supported by 4 implants and a CAD/CAM PEEK bar. Further studies are needed to confirm these outcomes.

CLINICAL EVALUATION OF REMOVABLE PARTIAL DENTURE CONSTRUCTED FROM 3D PRINTED RESIN PATTERN DESIGNED USING CAD CAM TECHNOLOGY

INTRODUCTION: Computer-assisted design, computer-assisted manufacture (CAD/CAM) can be successfully applied to the fabrication of removable partial denture (RPD) alloy frameworks and replace laboratory crafting techniques. The CAD/CAM techniques have been widely used for a long time to manufacture dental prostheses. Computer-aided technologies allow more precise and systematic modeling, and could therefore reduce the burdensome steps of both chair-side and laboratory work, saving vital time.OBJECTIVES: This study was aimed to compare between the accuracy of chrome-cobalt removable partial denture frameworks designed and fabricated using CAD/CAM technique with that fabricated using conventional techniqueMATERIALS AND METHODS: Seven maxillary bilateral partially edentulous patients having Class III modification 1 Kennedy classification were selected from those attended to the prosthodontic department, Faculty of Dentistry, Alexandria University. For each patient, two different cobalt chromium removable partial frameworks were constructed; the first one was fabricated using CAD CAM technique (group A)and the other framework was fabricated using conventional manufacturing technique(group B) and were compared through evaluation of: (1) Guiding plane/plate relation. (2) Accuracy of fit of occlusal rests and major connector.RESULTS: all removable partial dentures fabricated by CAD/CAM technology showed increased improvement of accurate adaptation of the palatal strap major connector, guiding plane\plate relation and fit of occlusal rest, also it was less time consuming and economic need compared to conventional technique.CONCLUSIONS: The use of CAD/CAM technology for fabrication of removable partial denture frameworks should be widely applied because of its favorable clinical accuracy.KEYWORDS: Removable partial denture, CAD/CAM, Guiding planes, Chrome-Cobalt powder, Occlusal rests adaptation.

Computer-assisted, template-guided immediate implant placement and loading in the mandible: a case report

BackgroundComputer-assisted implant planning has become an important diagnostic and therapeutic tool in modern dentistry. This case report emphasizes the possibilities in modern implantology combining virtual implant planning, guided surgery with tooth and implant supported templates, immediate implant placement and loading.Case presentationA straight forward approach was followed for the mandible presenting with hopeless lower incisors. Diagnosis, decision making and treatment approach were based on clinical findings and detailed virtual three-dimensional implant planning. Extractions of the hopeless mandibular incisors, immediate and guided implant placement of six standard implants, and immediate loading with a provisional fixed dental prosthesis (FDP) were performed fulfilling patient’s functional and esthetic demands. The final computer assisted design / computer assisted manufacturing (CAD/CAM) FDP with a titanium framework and composite veneering was delivered after 6 months. At the 1-year recall the FDP was free of technical complications. Stable bony conditions and a healthy peri-implant mucosa could be observed.ConclusionsComputer assisted implantology including three-dimensional virtual implant planning, guided surgery, and CAD/CAM fabrication of provisional and final reconstructions allowed for a concise treatment workflow with predictable esthetic and functional outcomes in this mandibular full-arch case. The combination of immediate implant placement and immediate loading was considerably more complex and required a high level of organization between implantologist, technician and patient. After the usage of a first tooth-supported surgical template with subsequent extraction of the supporting teeth, a second surgical template stabilized on the previously inserted implants helped to transfer the planned implant position in the extraction sites with a guided approach.

The Conometric Concept: A Two-Year Follow-Up of Fixed Partial CEREC Restorations Supported By Cone-In-Cone Abutments.

To evaluate the performance of definitive, implant-supported, lithium disilicate fixed dental prostheses (LS2 FDPs) manufactured with a computer-assisted design/computer-assisted manufacturing (CAD/CAM) system. All patients received two-unit restorations placed in posterior regions, supported by osseointegrated implants with cone-in-cone connection abutments. Two implants (Ankylos) were placed into healed sites or fresh extraction sockets in the maxillary/mandibular posterior regions of partially edentulous patients. Definitive digital impressions were made 3 months after surgery. Twenty-four patients received fixed monolithic LS2 restorations manufactured with the CEREC system. All restorations were connected to the implants using cone-in-cone connection abutments. Peri-implant pocket depths were recorded for 2 years at each follow-up visit. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the FDI World Dental Federation study design were assessed yearly until the last follow-up appointment. The opposing dentitions were identified by type of restoration and supporting structures at the time of placement of the definitive restorations and at the 2-year follow-up visits. One patient (4.16%) moved to an unknown location during the study. A total of 23 FDPs (95.8%) supported by 46 implants reached the 2-year follow-up. None of the prostheses failed, or became loose or detached. No significant difference involving probing levels between the experimental times were found. The results of this research indicated that the abutment-prostheses connection using a cone-in-cone approach was successful within the 2-year period of this study. None of the studied monolithic LS2 glass-ceramic prostheses milled using the CEREC CAD/CAM system fractured or became detached.

Dental Students’ Perceptions of Digital Assessment Software for Preclinical Tooth Preparation Exercises

Objective self-assessment is essential to learning and continued competence in dentistry. A computer-assisted design/computer-assisted manufacturing (CAD/CAM) learning software (prepCheck, Sirona) allows students to objectively assess their performance in preclinical prosthodontics. The aim of this study was to evaluate students' perceptions of CAD/CAM learning software for preclinical prosthodontics exercises. In 2014, all third-year dental students at Harvard School of Dental Medicine (n=36) were individually instructed by a trained faculty member in using prepCheck. Each student completed a preclinical formative exercise (#18) and summative examination (#30) for ceramometal crown preparation and evaluated the preparation using five assessment tools (reduction, margin width, surface finish, taper, and undercut) in prepCheck. The students then rated each of the five tools for usefulness, user-friendliness, and frequency of use on a scale from 1=lowest to 5=highest. Faculty members graded the tooth preparations as pass (P), marginal-pass (MP), or fail (F). The survey response rate was 100%. The tools for undercut and taper had the highest scores for usefulness, user-friendliness, and frequency of use. The reduction tool score was significantly lower in all categories (p<0.01). There were significant differences in usefulness (p<0.05) and user-friendliness (p<0.05) scores among the P, MP, and F groups. These results suggest that the prepCheck taper and undercut tools were useful for the students' learning process in a preclinical exercise. The students' perceptions of prepCheck and their preclinical performance were related, and those students who performed poorest rated the software as significantly more useful.

Novel Molecular Spectroscopic Multimethod Approach for Monitoring Water Absorption/Desorption Kinetics of CAD/CAM Poly(Methyl Methacrylate) Prosthodontics.

Water absorbed to poly(methyl methacrylate) (PMMA)-based CAD/CAM (computer-assisted design/computer-assisted manufacturing) prosthodontics can alter their properties including hardness and stability. In the present contribution, water absorption and desorption kinetics under defined experimental conditions were monitored employing several supplementary and advanced Fourier transform infrared (FT-IR) spectroscopic techniques in combination with multivariate analysis (MVA). In this synergistic vibrational spectroscopic multimethod approach, first a novel near-infrared (NIR) diffuse fiber optic probe reflection spectroscopic method was established for time-resolved analysis of water uptake within seven days under controlled conditions. Near-infrared water absorbance spectra in a wavenumber range between 5288-5100 cm-1 (combination band) and 5424-5352 cm-1 (second overtone) were used establishing corresponding calibration and validation models to quantify the amount of water in the milligram range. Therefore, 14 well-defined samples exposed to prior optimized experimental conditions were taken into consideration. The average daily water uptake conducting reference analysis was calculated as 22 mg/day for one week. Additionally, in this study for the first time NIR two-dimensional correlation spectroscopy (2D-COS) was conducted to monitor and interpret the spectral dynamics of water absorption on the prosthodontics in a wavenumber range of 5100-5300 cm-1. For sensitive time-resolved recording of water desorption, a recently developed high-temperature, high-pressure FT-IR reaction cell with water-free ultra-dry in situ and operando operation was applied. The reaction cell, as well as the sample holder, was fully made of quartz glass, with no hot metal or ceramic parts in the vicinity of the high temperature zone. Applying a temperature gradient in the range of 25-150 ℃, mid-infrared (MIR) 2D-COS was successfully conducted to get insights into the dynamic behavior of O-H (1400-1800 cm-1) absorption bands with increasing temperature over time and the release of CO2 (2450 cm-1) from the polymers. In addition, an ATR FT-IR imaging setup was optimized in order to investigate the surface homogeneity of the PMMA-based resins with a spatial resolution to 2 µm. From this vibrational spectroscopic multimethod approach and the collection of several analytical data, conclusions were drawn as to which degree the surface structure and/or its porosity have an impact onto the amount of water absorption.

Accuracy Assessment of Immediate and Delayed Implant Placements Using CAD/CAM Surgical Guides.

The aim of this study is to assess the accuracy of immediately placed implants using Anatomage Invivo5 computer-assisted design/computer-assisted manufacturing (CAD/CAM) surgical guides and compare the accuracy to delayed implant placement protocol. Patients who had implants placed using Anatomage Invivo5 CAD/CAM surgical guides during the period of 2012-2015 were evaluated retrospectively. Patients who received immediate implant placements and/or delayed implant placements replacing 1-2 teeth were included in this study. Pre- and postsurgical images were superimposed to evaluate deviations at the crest, apex, and angle. A total of 40 implants placed in 29 patients were included in this study. The overall mean deviations measured at the crest, apex, and angle were 0.86 mm, 1.25 mm, and 3.79°, respectively. The means for the immediate group deviations were: crest = 0.85 mm, apex = 1.10, and angle = 3.49°. The means for the delayed group deviations were: crest = 0.88 mm, apex = 1.59, and angle = 4.29°. No statistically significant difference was found at the crest and angle; however, there was a statistically significant difference between the immediate and delayed group at the apex, with the immediate group presenting more accurate placements at the apical point than the delayed group. CAD/CAM surgical guides can be reliable tools to accurately place implants immediately and/or in a delayed fashion. No statistically significant differences were found between the delayed and the immediate group at the crest and angle, however apical position was more accurate in the immediate group.

Comparations of the 3D Printing Methods for the Production of the Reporting Medical Models

The paper is focused on the area of manufacturing reporting medical models for verifications of custom made implants before the implantation. The CAD/CAM (computer-assisted design/computer-assisted manufacturing) trend of production of personalized implants supports the use of additive and subtractive production technologies with the creation of reporting medical models. The paper describes a geometrical comparison of four same patterns of the skull manufactured by different 3D printing technologies. It was realized actual-nominal comparison of CT scans of the medical models with CAD design of the skull as a reference. Deviations from the shape identified in our experiment, show the range from 1,89 mm to -0,91 mm.

Establishing CAD/CAM in Preclinical Dental Education: Evaluation of a Hands‐On Module

The aim of this study was to evaluate a hands-on computer-assisted design/computer-assisted manufacture (CAD/CAM) module in a preclinical dental course in restorative dentistry. A controlled trial was conducted by dividing a class of 56 third-year dental students in Germany into study and control groups; allocation to the two groups depended on student schedules. Prior information about CAD/CAM-based restorations was provided for all students by means of lectures, preparation exercises, and production of gypsum casts of prepared resin teeth. The study group (32 students) then participated in a hands-on CAD/CAM module in small groups, digitizing their casts and designing zirconia frameworks for single crowns. The digitization process was introduced to the control group (24 students) solely by means of a video-supported lecture. To assess the knowledge gained, a 20-question written examination was administered; 48 students took the exam. The results were analyzed with Student's t-tests at a significance level of 0.05. The results on the examination showed a significant difference between the two groups: the mean scores were 16.8 (SD 1.7, range 13-19) for the study group and 12.5 (SD 3, range 4-18) for the control group. After the control group had also experienced the hands-on module, a total of 48 students from both groups completed a questionnaire with 13 rating-scale and three open-ended questions evaluating the module. Those results showed that the module was highly regarded by the students. This study supports the idea that small-group hands-on courses are helpful for instruction in digital restoration design. These students' knowledge gained and satisfaction seemed to justify the time, effort, and equipment needed.

Color stainability of CAD/CAM and nanocomposite resin materials

Statement of problemThe color stainability of recently introduced computer-assisted design/computer-assisted manufacturing (CAD/CAM) hybrid ceramic and resin nanoceramic is unknown. PurposeThe purpose of this in vitro study was to compare the effect of coffee staining on the color of 3 different CAD/CAM restorative materials and a nanocomposite resin. Material and methodsSpecimens from a hybrid dental ceramic (VITA Enamic), a resin nanoceramic (Lava Ultimate), a lithium disilicate glass ceramic (IPS e.max CAD), and a nanocomposite resin (Filtek Supreme Ultra Universal) were evaluated for color change due to thermocycling in coffee (n=5). Specimens 0.5 to 0.7 mm and 1 to 1.2 mm in thickness were thermocycled for 5000 cycles. CIEDE2000 color differences (ΔE00) due to thermocycling in coffee were calculated using the color coordinates obtained from a spectroradiometer. ANCOVA was used to analyze the color differences among the materials with thickness as the covariate. Significant differences at average thickness were analyzed with the Tukey-Kramer test. ResultsFor color difference due to staining, thickness was a significant covariate (P<.001). Regarding the analysis of color differences, every pair of the tested materials was significantly different (P<.001). Least squares means of color differences (ΔE00) at mean thickness were 4.34 for the nanohybrid composite resin, 3.66 for the resin nanoceramic, 1.35 for the hybrid ceramic, and 0.43 for the lithium disilicate ceramic. ConclusionWhen exposed to hot and cold coffee, the color change was beyond clinical acceptability for the tested resin nanoceramic and nanocomposite resin materials. The average color change of the hybrid ceramic was clinically perceivable over the tested thickness values. The color change of lithium disilicate ceramic was not clinically perceivable at any tested thickness.

English

The improvement of digital dentistry such as the intraoral scanners and indirect restorations that can be fabricated with computer-assisted design/ computer-assisted manufacturing (CAD/CAM) technology, have changed clinicians approach for treating patients. This case report describes the fabrication of lithium disilicate inlay on an endodontically treated mandibular second molar with CAD/CAM restoration offering a conservative alternative for patients. The purpose of this article is to provide information on a particular technique to manage a case of an endodontically treated tooth by performing a treatment combining digital dentistry with conventional laboratory work. This technique demonstrated efficiency on the fabrication and adjustment of lithium disilicate inlay restoration.

Use of CAD/CAM to fabricate duplicate abutments for retrofitting an existing implant prosthesis: A clinical report

Computer-assisted design/computer-assisted manufacturing (CAD/CAM) technology has been widely used in the field of dentistry. Among CAD/CAM custom abutments, zirconia abutments are becoming more popular due to their favorable mechanical and esthetic properties. However, recent review articles show that fractured zirconia abutments are a common prosthetic complication. In this clinical report, a 72-year-old man presented with a dislodged implant-supported fixed prosthesis because of fractured zirconia abutments. This clinical report describes a successful application of CAD/CAM technology to fabricate duplicate abutments, which were retrofitted to the existing prosthesis.

Revision arthroplasty with a hip-inspired computer-assisted design/computer-assisted manufacturing implant for glenoid-deficient shoulders

Revision arthroplasty for failed post-traumatic humeral head replacement associated with rotator cuff and glenoid deficiency is challenging. Current surgical solutions are fraught with complications, and no best-practice strategy has been established. We hypothesized that the computer-assisted design/computer-assisted manufacturing (CAD/CAM) shoulder (Stanmore Implants, Elstree, UK), a total shoulder design resembling a total hip prosthesis, can offer a reliable alternative in this surgically challenging subset of patients with rotator cuff deficiency and advanced glenoid bone loss. Twenty-one patients with failed post-traumatic humeral head replacement associated with rotator cuff and glenoid deficiency underwent revision with CAD/CAM shoulders between 2005 and 2010. Clinical data were collected prospectively and analyzed at a mean follow-up of 3 years. After revision, the pain rating at rest (on a 0-10 numerical scale) decreased from 5.6 ± 1.3 to 1.1 ± 1.3 (P < .001) and pain during activity decreased from 7.4 ± 1.2 to 2.1 ± 1.8 (P < .001). The Oxford shoulder score improved from 47 ± 6 to 31 ± 9 (P < .001), and the subjective shoulder value (on a 0%-100% scale) improved from 22% ± 14% to 45% ± 18% (P < .001). Active shoulder range of motion was similar before and after revision. Postoperative complications occurred in 9 patients and included 1 infection, 2 periprosthetic fractures, 2 prosthetic dislocations, and 4 fixation screw fractures. No case of glenoid loosening occurred. The CAD/CAM shoulder offers a reliable method of securing a glenoid component in shoulders with advanced glenoid deficiency and should be considered as an alternative to other surgical methods in these challenging cases. At 3 years' follow-up, pain and clinical scores improved significantly and no case of glenoid loosening occurred.

Ceramic Machining Systems-A New Era in Prosthodontics

CAD/CAM ceramics are machinable ceramic materials formulated for the production of crowns and inlays through the use of computer aided designs and computer aided machining processes. CAD-CAM (computer assisted design-computer assisted manufacture) systems have also recently been introduced to the dental profession. All CAD/CAM systems are technically complex and involve three distinct steps that is collection of information design of the restoration and fabrication. These systems will undoubtedly receive periodic improvement, necessitating expense for software changes as well as tool replacement and other associated expenses. This paper outlines some interesting aspects of recent developments in ceramics and considers the present state of the art with respect to both materials and techniques.