CAD-CAM Technology Research Articles

3D printing for bone regeneration: challenges and opportunities for achieving predictability.

3D printing offers attractive opportunities for large-volume bone regeneration in the oro-dental and craniofacial regions. This is enabled by the development of CAD-CAM technologies that support the design and manufacturing of anatomically accurate meshes and scaffolds. This review describes the main 3D-printing technologies utilized for the fabrication of these patient-matched devices, and reports on their pre-clinical and clinical performance including the occurrence of complications for vertical bone augmentation and craniofacial applications. Furthermore, the regulatory pathway for approval of these devices is discussed, highlighting the main hurdles and obstacles. Finally, the review elaborates on a variety of strategies for increasing bone regeneration capacity and explores the future of 4D bioprinting and biodegradable metal 3D printing.

Methodology of CAD design and CAM production of transtibial prosthetic sockets

The digitization of the design process of lower limb prosthetic sockets seems to be necessary. Using modern CAD procedures and CAM technologies, it is possible to produce functional, individual prosthetic aids that bring many benefits compared to commonly used methods. However, the disadvantage of using CAD/CAM procedures can be the input costs for production technology and software. The aim of this research is to propose a low-cost solution for individual transtibial socket design and production. Modern methods and technologies like 3D scanning, CAD design and additive manufacturing have been applied. As a result, a transtibial stump positive and custom socket design methodology is proposed. In conclusions a total value of a custom transtibial socket design and production was calculated.

3D printing – A Revolutionary Change in Pediatric Dentistry

3D printing has emerged as a promising technology in the field of dentistry which has become a topic of great interest. 3D printing along with CAD-CAM technology is being able to construct a three- dimensional object by adding material layer by layer. Recently, 3d printing technology have played a major role in pediatric dentistry from printing of individualized imprint trays, orthodontic models, maxillo-facial growth evaluation, fabrication of a variety of prosthetics, crowns, during fracture, surgical cases, navigating complex root canal treatments in pediatric patients. 3D-printed models could be used for educational purposes in training students and trainees. The treatment outcomes could be visualized with 3D printing technology which has made it a promising clinical tool. 3D printing technology has the capacity to revolutionize dentistry and in the near future, it is going to change the face of pediatric dentistry.

Mechanical properties of 3D-printed and milled composite resins for definitive restorations: An in vitro comparison of initial strength and fatigue behavior.

To evaluate the flexural strength and fatigue behavior of a novel 3D-printed composite resin for definitive restorations. Fifty disc-shaped specimens were manufactured from each of a nanohybrid composite resin (NHC), polymer-infiltrated ceramic network (PICN), and 3D-printed composite resin (3D) with CAD-CAM technology. Biaxial flexural strength (σin ) (n = 30 per group) and biaxial flexural fatigue strength (σff ) (n = 20 per group) were measured using piston-on-three-balls method, employing a staircase approach of 105 cycles. Weibull statistics, relative-strength degradation calculations, and fractography were performed. The results were analyzed with 1-way ANOVA and Games-Howell post hoc test (α = 0.05). Significant differences in σin and σff among the groups (p < 0.001) were detected. The NHC group provided the highest mean ± standard deviation σin and σff (237.3 ± 31.6 MPa and 141.3 ± 3.8 MPa), followed by the PICN (140.3 ± 12.9 MPa and 73.5 ± 9.9 MPa) and the 3D (83.6 ± 18.5 MPa and 37.4 ± 23.8 MPa) groups. The 3D group exhibited significantly lower Weibull modulus (m = 4.7) and up to 15% higher relative strength degradation with areas of nonhomogeneous microstructure as possible fracture origins. The 3D-printed composite resin exhibited the lowest mechanical properties, where areas of nonhomogeneous microstructure developed during the mixing procedure served as potential fracture origins. The clinical indications of the investigated novel 3D-printed composite resin should be limited to long-term provisional restorations. A cautious procedure for mixing the components is crucial before the 3D-printing process, since nonhomogeneous areas developed during the mixing could act as fracture origins.

Using the foundation restoration as a blueprint: An uncomplicated approach to retrofitting crowns to existing removable partial dentures using CAD-CAM technology

Removable partial dentures have been used to rehabilitate partially edentulous patients for decades. A challenging but commonly encountered procedure is retrofitting a crown to an existing removable partial denture. Several techniques have been proposed for fabricating these complex prostheses, some involving the intraoral application of polymers to the abutment tooth or making impressions of the preparation with the removable prosthesis seated. The present technique presents an approach that simplifies the design and fabrication of retrofitted crowns for fractured abutment teeth needing foundation restorations. This approach involves the implementation of computer-aided design and computer-aided manufacturing technology to record and utilize the contours of the foundation restoration established intraorally as a blueprint for the retrofitted crown.

The Use of a CAD/CAM Thermoformed Splints System in Closed Reduction of Condylar Fractures.

(1) Background: Mandibular fractures are very common. Common indications of closed treatment for mandibular fractures are non-displaced or minimally displaced simple fractures in adult compliant patients with good dentition, the absence of occlusal disruption, and fractures in growing children. In closed treatment, the mandible is maintained in centric occlusion with a maxillomandibular fixation (MMF) with orthodontic elastics. Many methods of MMF have been described, often using orthodontic appliances. In recent years, CAD-CAM technology has improved many procedures used in maxillofacial surgery and orthodontics. The device we present is manufactured following a digital workflow, and was designed specifically for MMF. (2) Materials: Two patients with mandibular fractures were treated with an MMF method whose procedure comprised scanning of the dental arches, followed by construction of thermoformed splints on which buttons for the elastics and retention holes are made. The splints were fixed on the dental arches with composite resin at the level of the holes, and were kept in place for the period of healing of the fracture, with the intermaxillary elastics hooked to the buttons. (3) Results: The application time of the splints was very quick. The splints remained stable for the necessary time, without causing particular discomfort to the patients. (4) Conclusions: From our experience, this technique has proved to be reliable and reproducible and could represent a valid tool in the closed treatment of mandibular fractures.

Self-designed three-dimensional printed skeletal anchorage titanium device for orthopaedic traction in a growing Class III patient

Maxillary retrusion in a growing skeletal class III patient can be treated with growth modification by facemask therapy with skeletal anchorage. A 12-year-old boy presented with Skeletal Class III relationship, retrognathic maxilla and paranasal deficiency. Cone beam computer tomography (CBCT) was taken for the design of the customized skeletal anchorage device with a 3D planning computer software. Two pairs of skeletal anchorage surgical guides and plates were designed with the correct vector and location, and to avoid tooth roots in the fixation. The plates were printed with titanium and fixed onto the patient for the facemask therapy. CAD-CAM technology allows customization and precise execution of the skeletal anchorage for the facemask therapy. Self-designed 3D printed skeletal anchorage device, with the advantages of increased rigidity, ease of placement and accuracy of force application, can be a valid alternative to stock titanium plates.

Coupling of multilayer CAD-CAM prosthetic components: Computing the user interaction influence on the adhesion interface geometry

The fracture resistance of multilayer zirconia crowns has recently been proven to be improved by using lithium millable disilicate glass–ceramic blocks (D’Addazio in Materials, 2020). Accordingly, the framework and the ceramic coating are designed and milled using a CAD-CAM technology and the two separated prosthetic components are then manually assembled by the dental technician and glued with the fusion of a glass–ceramic material. It is essential, during the CAD phase, to design a gap between the framework and the decorative veneer that will later be filled by the fused ceramic.Since the act of gluing the two parts is manually performed by the dental technician, we aim at investigating the operator influence on the final gap with respect to the designed gap. For this purpose, an original geometrical investigation method was developed to enable the 3D digital analysis of the whole fusion interface. During the CAD design stage, two technicians input a different setting for the gap between the two components. The framework and veneering structure were designed, the milled components were produced, and the zirconia framework was sintered, then the two CAD-on prosthetic components were scanned before and after their fusion/crystallization to analyze the physical internal gap. The results show that manual assembly cancels out any effect of the precision settings adopted during CAD-CAM design of the components, as well as any benefit expected from machining on a CNC milling machine, thus requiring, as a last step, manually retouching the prosthesis to correctly fit in the mouth.

Evaluation of the Effect of Different Glazing Brands on Surface Roughness of Monolithic Zirconia

The effect of glazing on the mechanical properties of monolithic high translucent zirconia is widely used to fabricate highly aesthetic and strong dental restorations using CAD-CAM technology. The purpose of this study was to evaluate the surface roughness of different glazing brands' materials on monolithic Zirconia. 40 specimens from Zirconia block (VITA YZ®XT Color, Diameter 98.4x14mm height) were prepared by computer-aided design/computer-aided manufacturing machined (Imes-Icore, 5 axis, COR TEC 250i dry, Germany). The samples dimension for the surface roughness test (diameter 10 mm and thickness 2 mm) by using a surface roughness testing machine profilometer (TR200, Germany), divided into 3 groups depending on types of glazing brands materials (VITA, VITA AKZENT® Plus, glaze LT, Germany), the second group with (Ivoclar Vivadent, IPS e.max Ceram glaze and stain liquid, Liechtenstein), and the third group with (GC Initial spectrum glaze liquid, Austria). The data were analyzed statistically using the package for social science, (ANOVA) test with the Bonferroni test to accept or reject the statistical hypothesis. For the roughness readings, the GC group had the greatest mean value of surface roughness in zirconia (0.721±0.014), followed Ivoclar group (0.663 ± 0.030), and then the VITA group (0.641±0.021). There was a statistically significant difference between (VITA&amp;GC) and (Ivoclar &amp; GC) with a p-value &lt; 0.05, except between VITA with Ivoclar, there was no statistically significant association with a p-value &gt; 0.05 for both. Zirconia glazed with GC paste (powder, fluid) has higher surface roughness than samples glazed with Ivoclar paste (powder, fluid) followed by the VITA group which has lower surface roughness. The results concluded that the monolithic zirconia glazed with GC glaze material displays a higher surface roughness than Ivoclar and VITA glaze.

Predictability and Effectiveness of Jaws Reconstructive Prosthesis after Tumor Removal: A Systematic Review and Meta-Analysis

Vascular-free flaps are the most frequently employed method in cases of jaws reconstruction after large tumor removal. This therapeutic choice is due to its intrinsic blood supply, which speeds up recovery and enables healing apart from the injured recipient site. This method is most commonly used in secondary reconstructions brought on by radiation, infection, or prior surgical intervention. In fact, with the help of 3d technology, guides can be designed to perform the grafting very smoothly. The purpose of this review with meta-analysis is to compare the two methods: the one using 3d and the freehand one. Methods: In accordance with the entered keywords, a literature search was conducted on PubMed, Lilacs, and Web of Science. Articles published between 2000 and 4 January 2023 were taken into consideration. Using the Boolean connective AND, the terms “jaw reconstruction”, “cad-cam”, and “cancer” have been joined. Results: After searching the three search motors, 148 articles were selected, and only 7 were chosen for this review. Conclusions: The pre-operative morphological position looks to be accurately restored using the CAD/CAM reconstructive methodology. Reconstruction using CAD-CAM and 3d technology allows for greater accuracy, less operative time, and improved aesthetics.

The Influence of a Novel, Crenelated Design of CAD-CAM Ceramic Veneers on the Debonding Strength.

(1) Background: Aesthetic dentistry has become one of the most dynamic fields in modern dental medicine. Ceramic veneers represent the most appropriate prosthetic restorations for smile enhancement, due to their minimal invasiveness and highly natural appearance. For long-term clinical success, accurate design of both tooth preparation and ceramic veneers is of paramount importance. The aims of this in vitro study were to assess the stress in anterior teeth restored with Computer-Aided Design (CAD) and Computer-Aided Manufacturing (CAM) ceramic veneers and compare the resistance to detachment and the fracture of ceramic veneers prepared using two different designs. (2) Methods: Sixteen lithium disilicate ceramic veneers were designed and milled using the CAD-CAM technology and divided into two groups according to the preparations (n = 8): Group 1, conventional (CO), with linear marginal contour and Group 2, crenelated (CR), the latter with our novel (patented) sinusoidal marginal design. All samples were bonded to anterior natural teeth. The mechanical resistance to detachment and fracture was investigated by applying bending forces on the incisal margin of the veneers in order to determine which type of preparation leads to better adhesion. An analytic method was employed, as well, and the results of the two approaches were compared. (3) Results: The mean values of the maximum force recorded at the veneer detachment were 78.82 ± 16.55 N for the CO group and 90.20 ± 29.81 N for the CR group. The relative increase, equal to 14.43%, demonstrated that the novel CR tooth preparation provided higher adhesive joints. In order to determine the stress distribution within the adhesive layer, a finite element analysis (FEA) was performed. The statistical t-test showed that the mean value of the maximum normal stresses is higher for the CR-type preparations. (4) Conclusions: The patented CR veneers represent a practical solution to augment the adhesion and mechanical properties of ceramic veneers. The obtained results demonstrated that CR adhesive joints triggered higher mechanical and adhesive forces, which subsequently led to a higher resistance to detachment and fracture.

Treatment of a Class II malocclusion with computer-aided design and manufacture of a fixed Twin-block appliance combined with customized labial brackets

• Fixed Twin-block appliance combined with customized labial bracket can treat Class II malocclusion. • CAD/CAM technology contributed to the manufacture of the appliances. • Fixed Twin-block brought satisfactory treatment outcomes. • Treatment outcomes were better in adolescents than in adults. Class II malocclusion is common in clinical practice, and Twin-block appliances have been widely used for orthopedic treatment. This article introduces the design and clinical application of a fixed Twin-block appliance combined with a customized labial bracket. Computer-aided design and manufacturing (CAD-CAM) technologies were used to design and manufacture the appliances. The components of the Twin-block appliance were manufactured by casting them in a 3-dimensionally printed wax analog and were connected through laser welding. Customized labial fixed appliances were manufactured with CAD-CAM technology and bonded using indirect bonding. The acrylic resins used to fill the occlusal surface were gradually ground during fixed orthodontic treatment. These appliances were used to treat a 13-year-old girl and a 33-year-old woman presenting with Class II malocclusion with mandibular retrusion and large overjet. The fit of the CAD-CAM-generated appliances was precise, and they helped shorten the treatment period. Superior treatment outcomes improve the prospects of functional orthodontic treatment.

Surface Microhardness of Different Ceramic Materials Used for Esthetic Full-Ceramic Veneers

The study examines the microhardness of five ceramic materials using CAD-CAM technology. Twenty-five disc-shaped specimens for the study, using I.P.S. Empress CAD (fully sintered), I.P.S. e.max CAD (30 minutes) and Vita Suprinity (26 minutes) milled in a pre-crystallized stage, Coprasmile (8 hours), and Zenostar milled in partially sintered stage (9 hours and 50 minutes). Each specimen had ten indentations, with a 1000-gram load applied for 10 seconds using a Vickers diamond indenter. Vickers values were automatically converted to microhardness using the formula Hv = 1.8544×F/d2. IBM SPSS 26 for statistical analysis, calculating microhardness values for each group. One-way ANOVA and Tukey HSD posthoc test compared differences between ceramic groups at a P &lt;0.05 significance level. Results showed significant differences among the means (P &lt;0.05), with Coprasmile, Zenostar, and Suprinity groups having the highest and lowest values, respectively.

Quality of Life after Mandibular Reconstruction Using Free Fibula Flap and Customized Plates: A Case Series and Comparison with the Literature.

A single-center retrospective study was conducted to assess health-related quality of life (HRQoL) in 23 consecutive patients undergoing mandibular reconstruction using the computer-aided design (CAD) and computer-aided manufacturing (CAM) technology, free fibula flap, and titanium patient-specific implants (PSIs). HRQoL was evaluated after at least 12 months of surgery using the University of Washington Quality of Life (UW-QOL) questionnaire for head and neck cancer patients. In the 12 single question domains, the highest mean scores were found for "taste" (92.9), "shoulder" (90.9), "anxiety" (87.5), and "pain" (86.4), whereas the lowest scores were observed for "chewing" (57.1), "appearance" (67.9), and "saliva" (78.1). In the three global questions of the UW-QOL questionnaire, 80% of patients considered that their HRQoL was as good as or even better than it was compared to their HRQoL before cancer, and only 20% reported that their HRQoL had worsened after the presence of the disease. Overall QoL during the past 7 days was rated as good, very good or outstanding by 81% of patients, respectively. No patient reported poor or very poor QoL. In the present study, restoring mandibular continuity with free fibula flap and patient-specific titanium implants designed with the CAD-CAM technology improved HRQoL.

Theoretical and practical aspects regarding the role of the working model in the workflow of porcelain fused to metal fixed restorations - Preliminary study

In dental practice, the fidelity of a model is given by the quality and type of material used, the technique by which it is made, and last but not least by the experience and skill of the dental technician. But, the emergence of CAD-CAM technology has led to a major change in the stages of making the working model, through the development of the virtual model. Thus, the purpose of this material is to perform a comparative study between several techniques for obtaining sectional working models, with or without pins, compared to the virtual model obtained by CAD-CAM technique.

Numerical investigation of the stress-strain state of zirconium dioxide pin structures manufactured using CAD CAM technologies

Numerical studies were carried out to determine the stress-strain state of pin stump structures made of zirconium dioxide. The calculation models were part of the dentoalveolar segment in the form of a cylinder, composed of a single-rooted tooth, dentin, periodontal ligament, compact bone of the alveolus, gums, spongy bone and a monolithic structure consisting of a crown fixed on a stump insert and a rod-pin. Three cases of such pin design models were considered. A numerical study was carried out for three different thicknesses of the rod, which were modeled as follows: the volume of the 2nd and 3rd pins doubled compared to the previous one – case 1 (thin rod), case 2(medium) and case 3 (thick). The finite element method was used to study the field of displacements and stresses according to von Mises both in the structures themselves and in the tissues surrounding them. Two cases of the load on the chewing surface of the tooth crown were established for comparative analysis in all cases: a distributed vertical load of 100 N and the same load at an angle of 45°. As a result of numerical studies, pin structures case 2 and 3 showed an ad-vantage over the design with a thin rod (case 1) both in terms of displacements and stresses. Case2 (average rod thickness) is recommended for use in practice. Structures of this type can be used to restore the crown part of the tooth in case of its complete absence or significant destruction, as well as a support for a bridge prosthesis.

Comparative Study of Dental Custom CAD-CAM Implant Abutments and Dental Implant Stock Abutments.

The implementation of CAD-CAM systems in dentistry has significantly influenced the evolution of dental implantology and implant-supported prosthetics within the past three decades. Implant-supported prostheses are comfortable and aesthetic. The prosthetic abutment has also faced a rapid design evolution, from the individualization of standard stock abutments offered by various manufacturers to a modern customization process using CAD-CAM technology. This paper presents a comparative study between 20 dental custom CAD-CAM implant abutments and 20 dental implant stock abutments, based on a set of measurements performed on the digital casts obtained from 24 cases of prosthetic rehabilitation on implants. The statistical analysis (Mann-Whitney U test) revealed significant differences between these two types of abutments: the incisal margin line diameter dimensions for custom abutments were significantly improved compared to standard abutments at the cervical level (U = 343.00, z = 3.868, p < 0.0005) and the incisal/occlusal level (U = 352.00, z = 4.112, p < 0.0005), while the inclination angle of the custom abutments relative to the 0-axis was significantly smaller than that of standard abutments (U = 115.50, z = -2.286, p = 0.022). The use of custom abutments leads to an increase in the final size of the abutment, an improvement in the retention of the prosthetic work, and reduces the angulation of the abutment in relation to the implant axis, thus decreasing the risk of unscrewing or fracturing the dental screw.

Graphene-Doped Polymethyl Methacrylate (PMMA) as a New Restorative Material in Implant-Prosthetics: In Vitro Analysis of Resistance to Mechanical Fatigue

Provisional prostheses in restorations over several implants with immediate loading in completely edentulous patients increase the risk of frequent structural fractures. An analysis was performed of the resistance to fracture of prosthetic structures with cantilevers using graphene-doped polymethyl methacrylate (PMMA) resins and CAD-CAM technology. A master model was produced with four implants measuring 4 mm in diameter and spaced 3 mm apart, over which 44 specimens representing three-unit fixed partial prostheses with a cantilever measuring 11 mm were placed. These structures were cemented over titanium abutments using dual cure resin cement. Twenty-two of the 44 units were manufactured from machined PMMA discs, and 22 were manufactured from PMMA doped with graphene oxide nanoparticles (PMMA-G). All of the samples were tested in a chewing simulator with a load of 80 N until fracture or 240,000 load applications. The mean number of load applications required for temporary restoration until the fracture was 155,455 in the PMMA-G group versus 51,136 in the PMMA group. Resistance to fracture under cyclic loading was three times greater in the PMMA-G group than in the PMMA group.

Evaluation of trueness and precision of removable partial denture metal frameworks manufactured with digital technology and different materials.

The aim of this study is to evaluate the accuracy of removable partial denture (RPD) frameworks produced using different digital protocols. 80 frameworks for RPDs were produced using CAD-CAM technology and divided into four groups of twenty (n = 20): Group 1, Titanium frameworks manufactured by digital metal laser sintering (DMLS); Group 2, Co-Cr frameworks manufactured by DMLS; Group 3, Polyamide PA12 castable resin manufactured by multi-jet fusion (MJF); and Group 4, Metal (Co-Cr) casting by using lost-wax technique. After the digital acquisition, eight specific areas were selected in order to measure the Δ-error value at the intaglio surface of RPD. The minimum value required for point sampling density (0.4 mm) was derived from the sensitivity analysis. The obtained Δ-error mean value was used for comparisons: 1. between different manufacturing processes; 2. between different manufacturing techniques in the same area of interest (AOI); and 3. between different AOI of the same group. The Δ-error mean value of each group ranged between -0.002 (Ti) and 0.041 (Co-Cr) mm. The Pearson's Chi-squared test revealed significant differences considering all groups paired two by two, except for group 3 and 4. The multiple comparison test documented a significant difference for each AOI among group 1, 3, and 4. The multiple comparison test showed significant differences among almost all different AOIs of each group. All Δ-mean error values of all digital protocols for manufacturing RPD frameworks optimally fit within the clinical tolerance limit of trueness and precision.

A systematic review and meta-analysis of the clinical performance of implant-supported overdentures retained by CAD-CAM bars.

To evaluate the performance of IODs involving CAD-CAM bars. A comprehensive search of studies published until May 2023 was conducted in many databases, including PubMed/MEDLINE, Web of Science, Cochrane Library, and SciELO, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The population, intervention, comparison, outcome (PICO) question was: "How do IODs retained by bars fabricated by CAD-CAM technology perform in daily clinical practice?" The meta-analysis included clinical studies based on effect size and a two-tailed null test with a 95% confidence interval (CI). Ten studies were included in the meta-analysis. Among them, nine reported a 100% implant survival rate for all CAD-CAM milled bars. Complications were reported in two studies with CAD/CAM-milled titanium bars, and one study reported more fractures in soldered gold bars used in maxillary rehabilitation. However, no fractures were observed in IODs retained by PEEK and zirconia bars. According to six studies, biological complications, including peri-implantitis, were minimal in the BioHPP and PEEK bar groups, while no cases were reported in the titanium or zirconia bar groups. CAD-CAM-milled zirconia bars had higher plaque and bleeding indices compared with titanium bars, as evidenced by findings from five studies. All four studies that evaluated Oral Health Impact Profile (OHIP) scores showed a positive effect of IODs retained by CAD-CAM milled titanium bars on quality of life. Patient satisfaction and acceptance by prosthodontists were significantly high, according to the results of five studies. Overdentures retained with CAD-CAM milled titanium bars show great potential for use in daily clinical practice. Moreover, patient and practitioner satisfaction was very high when this method was used.