Computer-aided Design Manufacturing Research Articles

Reasons for Failure of CAD/CAM Restorations in Clinical Studies: A Systematic Review and Meta-analysis.

The systematic review presented herein was performed to descriptively analyze the causes for the failure of computer-aided design/computer-aided manufacture (CAD/CAM) restorations. The meta-analysis reported herein was performed to estimate long-term survival and success rates of CAD-CAM fabrications. Using the PICOS paradigm, a systematic search was carried out in the PubMed and Cochrane databases to identify randomized controlled trials (RCTs) and prospective observational studies reporting survival data for CAD/CAM restorations. After selecting studies with a predefined set of selection criteria, data from included prospective clinical studies and RCTs were used for a systematic review aimed at a descriptive analysis of factors associated with failure of CAD-CAM restorations. Data from the included prospective clinical studies were used for meta-analysis, wherein 5-year and 10-year survival and success rates were estimated using Poisson regression models. The systematic review included data from 9 RCTs and 6 observational studies, which had a median follow-up of 36 months and 60 months, respectively. About 58 failures and 118 technical/ biological complications were noted in the included RCTs and 9 failures along with 58 technical/biological complications were noted in the prospective clinical studies. Poisson regression indicated an estimated 5-year and 10-year survival rates of 85.55-100 and 71-100, respectively. The estimated 5-year and 10-year success rates were 74.2-92.75 and 33.3-85.5, respectively. Several technical and biological complications contribute to failure of CAD/CAM restorations. However, CAD/CAM restorations with routine chairside materials might have clinically meaningful success rates in the long term. The results presented herein indicate that optimal strategies for mitigation of biological and technical complications may augment the success of CAD/CAM fabrications in restorative dentistry. Studies aimed at identification of such strategies are needed to further enhance the long-term success rates of CAD/CAM restorations.

Resin composite layering on discolored substrates ensures masking ability for monolithic ceramics.

the aim of this study was to evaluate the effect of resin composite layering on discolored substrates to obtain masking ability with monolithic ceramics. Four groups (n = 8) of computer-aided design/computer aided manufacturing (CAD/CAM) monolithic ceramics, shade A1, with thicknesses of 1.0 and 1.5 mm, were tested: feldspathic (FC), leucite-reinforced (LC), lithium disilicate-reinforced (LD), and translucent zirconia (5YSZ). Five substrates were used: A1 (used as reference), A3.5, C4, and coppery and silvery metals. The substrates were separated as non-layered or layered (with flowable opaque resin composite (FL), white opaque restorative resin composite (WD), and A1-shaded opaque restorative resin composite (A1D)). Resin composite layers of 0.5 and 1.0 mm were tested. The try-in paste, shade A1, was used as a luting agent. Translucency parameter (TP00 ) was assessed for the ceramics. Color differences (∆E00 ) were assessed for the restorative ceramics and resin composite layers over discolored substrates with the CIEDE2000 formula. The results were compared statistically, and descriptively with acceptability (AT, 1.77) and perceptibility (PT, 0.81) thresholds. Feldspathic showed the highest TP00 (for both ceramic thicknesses) and LD the lowest (for 1.5 mm of ceramic thickness) (P < 0.001). For substrate A3.5, layering with 1.0 mm of A1D or WD ensured ∆E00 below PT for all ceramics tested (P < 0.001). The use of 0.5 mm of FL or 1.0 mm of A1D associated with ceramics LC, LD, and 5YSZ ensured ∆E00 below AT for substrates C4 and coppery metal (P < 0.001). Silvery background layered with 0.5 mm of FL presented ∆E00 below AT for all ceramics and ∆E00 below PT for lithium disilicate of 1.0 mm of thickness (∆E00 = 0.72). Layering severely discolored substrates with selected opaque resin composites ensures masking ability for restoration with CAD/CAM monolithic ceramics. Severely discolored substrates are predictably restored with monolithic CAD/CAM ceramics by performing a previous layering of the substrate with opaque resin composite.

Novel concept for posterior crossbite correction : Preliminary results.

The efficiency of dentoalveolar compensation involving both jaws for posterior crossbite correction using computer-aided design/computer-aided manufacturing (CAD/CAM) expansion and compression archwires was evaluated. Treatment outcome was tested against the null hypothesis that the transverse correction achieved would be significantly smaller than planned. This retrospective study included 64patients (mean age 23.5years, median17.0, minimum/maximum:9.0/63.0, standard deviation13.7) with uni- or bilateral posterior crossbite. In all consecutively debonded patients, expansion and/or compression archwires were used for dentoalveolar correction involving both jaws. Plaster casts prior to(T1) and following treatment(T2) with completely customized lingual appliances (CCLA) were compared with the treatment plan represented by an individual target set-up. The statistical analysis was carried out using the Schuirmann TOST (two one-sided t‑tests) equivalence test on the basis of aone-sample t‑test with α = 0.025 to one side. The non-inferiority margin was set at δ = 0.5 mm. All posterior crossbites could be corrected by dentoalveolar compensation involving both jaws. The mean total correction achieved was 6.9 mm (mean maxillary expansion: 4.3 mm/mean mandibular compression: 2.6 mm) with amaximum of 12.8 mm. The transverse corrections achieved in both arches atT2 were equivalent to the planned corrections in the set-up (p < 0.001). The results of this study indicate that CAD/CAM expansion and compression archwires can be an efficient tool to achieve the desired correction in patients with aposterior crossbite even in more severe cases.

Clinical Outcomes of CAD/CAM (Lithium disilicate and Zirconia) Based and Conventional Full Crowns and Fixed Partial Dentures: A Systematic Review and Meta-Analysis.

Although CAD/CAM (computer-aided design/computer-aided manufacturing) restorations act as a favorable alternative to conventional metal-ceramic restorations for fixed dental prostheses, little is known about their intermediate and persistent clinical performance. This systematic review and meta-analysis aimed to assess the clinical performance in terms of biological, technical, and esthetic aspects and the survival and success ratios for single full crowns (SFCs) and fixed partial dentures (FPDs) fabricated by CAD/CAM and conventional techniques and according to the materials used (zirconia {ZC} and lithium disilicate {LD}). The population, intervention, control, outcome, and study design (PICOS) strategy was used to electronically search key terms in the PubMed, Cochrane Library, Embase, and Wiley Online databases for randomized control trials (RCTs) and cohort studies. The bias risks for RCTs and cohort studies were assessed using the Cochrane collaboration tool and the Newcastle-Ottawa Scale (NOS). Meta-analysis was performed using Rev5 from Cochrane. A total of 13 studies reporting on 1598 restorations in 1161 patients with a mean observation period of 3.6 years (minimum-maximum: 1-9.3 years) met the inclusion criteria. Meta-analysis of the included studies indicated that CAD/CAM manufacturing resulted in 1.17, 1.14, and 16.88 (95% CI: 0.64-2.17, 0.86-1.52, 7.59-37.56) higher biological, technical, and esthetic complications than conventional manufacturing of restorations. However, the difference was significant for esthetic complications only (p<0.00001). A significant difference was observed for all biological, technical, and aesthetic aspects between SFCs and FPDs (odds ratio {OR} = 2.61 vs. 1.78, 95% CI: 1.92-3.56 vs. 1.33-2.38; p<0.00001). The survival ratio of SFCs was 2.69 (95% CI: 1.98-3.65), significantly higher compared to the 1.76 (95% CI: 1.31-2.36) of FPDs (p<0.00001). The success ratio of FPDs at 1.18 (95% CI: 0.83-1.69) was significantly lower compared to SFCs at 2.36 (95% CI: 1.68-3.33). The clinical performance of LD with 2.42 (CI: 1.16-5.03) was significantly higher compared to ZC with 2.22 (CI: 1.78-2.77) (p<0.00001). The biological, technical, and aesthetic behaviors showed similar clinical outcomes between the CAD/CAM and conventional groups. LD could be a good alternative to zirconia, but its intermediate or persistent clinical performance needs to be evaluated. Overall, zirconia and CAD/CAM techniques must evolve further to outclass the conventional techniques used in the fabrication of SFCs and FPDs.

Mechanical Properties, Fractal Dimension, and Texture Analysis of Selected 3D-Printed Resins Used in Dentistry That Underwent the Compression Test.

Three-dimensional printing is finding increasing applications in today's world. Due to the accuracy and the possibility of rapid production, the CAD/CAM (computer-aided design/computer-aided manufacturing) technology has become the most desired approach in the preparation of elements, especially in medicine and dentistry. This study aimed to compare the biomechanical properties, fractal dimension (FD), and texture of three selected materials used for 3D printing in dentistry. Three biomaterials used in 3D printing were evaluated. The materials were subjected to the compression test. Then, their mechanical features, FD, and texture were analyzed. All the tested materials showed different values for the studied properties. The only statistically insignificant difference was observed for the force used in the compression test. All three materials showed differences in width and height measurements. The difference in the decrease between the compression plates was also significant. For Dental LT Clear, the mean value was 0.098 mm (SD = 0.010), while for BioMed Amber it was 0.059 mm (SD = 0.019), and for IBT it was 0.356 mm (SD = 0.015). The nominal strain also differed between the materials. IBT had the highest mean value (7.98), while BioMed Amber had the smallest (1.31). FD analysis revealed that Dental LT Clear did not show differences in the structure of the material. The other two materials showed significant changes after the compression test. Texture analysis (TA) revealed similar results: BioMed Amber resin showed significantly less pronounced texture changes compared to the other two materials. BioMed Amber also showed the most stable mechanical properties, whereas those of IBT changed the most. Fractal analysis revealed that IBT showed significant differences from the other two materials, whereas TA showed that only Dental LT Clear did not show changes in its texture after the compression test. Before the compression, however, BioMed Amber differed the most when bone index was taken into account.

Efficacy of CAD/CAM technology in dental procedures performed by students: A systematic scoping review of randomized clinical trials

ObjectivesTo assess the efficacy of computer-aided design/computer-aided manufacturing (CAD/CAM) in dental procedures performed by dental students. Methods: A systematic scoping review was performed. MeSH terms and keywords were specified to assess randomized clinical trials (RCTs) in all idioms. Results: Nine RCTs that include 520 students were selected. Two RCTs studied implant placement, and the rest of the trials explored implant impressions, intraoral scans, canal obturation, head positioning errors in panoramic images, deep caries and pulp exposure, diagnosis of temporomandibular disorders, and a tooth for restorations. Considering efficacy, variable results were found. The RCTs that explored implant impressions, deep caries and pulp exposure, and diagnosis of temporomandibular disorders showed better results when CAD/CAM technology was performed by students. Two RCTs that investigated implant placement presented contradictory outcomes; one showed better results when CAD/CAM systems were used while the other described similar results to conventional methods. The remaining RCTs did not find differences with conventional procedures. Considering the time spent during the procedures, two studies showed no differences between groups, while another indicated that the time spent was less for digital impressions (p < 0.001). A continuous decrease in scanning time was also perceived for all groups as skills in intraoral scanning augmented (p = 0.0005). Students indicated an interest in utilizing the CAD/CAM systems and recognized that their abilities were enhanced. Conclusions: Considering the limitations of this review and the limited number of RCTs evaluated, students recognized that their skills improved using CAD/CAM systems; however, only in some specific procedures greater efficacy and less time spent were observed when this technology was used. Dental students also showed great interest in using these techniques.

Flexural Strength Properties of Five Different Monolithic Computer-Aided Design/Computer-Aided Manufacturing Ceramic Materials: An In Vitro Study.

Objective The purpose of this in vitro study is to compare the flexural strength and Weibull modulus of 5 different monolithic computer-aided design/computer-aided manufacturing (CAD/CAM) ceramics. Methods A total of 50 specimens were fabricated, 10 from each of the following materials: lithium disilicate-based ceramic (IPS e.max CAD), zirconia -reinforced lithium-silicate ceramic (Vita Suprinity), leucite-based glass ceramic (IPS Empress CAD), and two zirconia-based ceramics (Zenostar and CopraSmile). The specimens were 4 mm wide, 2 mm thick, and 16 mm long. Flexural strength test was executed using a universal testing machine (Model 5980, Instron Industrial Products, Norwood, MA, USA). The two-parameter Weibull distribution function was used to analyze the variability of flexural strength values. Statistical analysis was performed on SPSS Version 23 (IBM Corp., Armonk, NY, USA) using one-way analysis of variance (ANOVA) and post-hoc Tukey's test. Results Suprinity had the highest Weibull modulus value, while Empress CAD displayed the lowest value. One-way ANOVA showed significant difference in the flexural strength between the different materials tested (p<0.05). Post-hoc analysis revealed significant differences among all the test groups in terms of flexural strength. Zenostar presented the highest mean flexural strength value (1033.90 MPa), while Empress CAD had the lowest value. Conclusion High-translucency zirconia had superior flexural properties than translucent zirconia, lithium disilicate ceramics, zirconia-reinforced lithium silicate ceramics, and leucite-based glass ceramics.

Patient-Specific Implants for Correction of Midfacial Aging.

The nasolabial folds (NLFs) may be shallowed with the use of nostril base augmentation. This study aimed to design and customize patient-specific implants (PSIs) with computer-aided design/computer-aided manufacturing (CAD/CAM) to correct NLF deepening caused by midfacial aging. The patient's head computed tomography data obtained and were used for reconstruction. The PSIs were customized by CAD/CAM techniques, which were implanted into a nasal base for shallow NLFs caused by midfacial aging. Preoperative and postoperative photos and a wrinkle severity rating scale were used to evaluate the changes in NLFs. Also, the global esthetic improvement scale was used to investigate the surgical satisfaction of patients. Eleven patients (22 NLFs) received PSIs in the nasal base (22 implants). The customized PSI matched well with premaxilla, reducing the difficulty of operation. After 3 to 12 months of follow-up, PSI was stable without foreign body reaction or inflammatory reaction. Postoperative wrinkle severity rating scale scores showed that NLF severity was reduced in all patients, with a significant esthetic improvement compared with preoperatively ( P < 0.01). The global esthetic improvement scale showed an extremely satisfied improved NLF in 27.27% of patients, much improved in 63.63%, and improved in 9.90% (2/22), and none reported change or poor NLF. Patient satisfaction with their midface appearance differed significantly before and after surgery ( P < 0.01). Individualized PSI designed with high precision and matching degree by CAD and prepared using CAM could be applied to overcome the limitations of noncustomized implants.

Fracture strength of implant-supported hybrid abutment crowns in premolar region fabricated using different restorative CAD/CAM materials.

The present study investigated the fracture strength of hybrid abutment crowns (HACs) in the premolar region that were fabricated with different restorative computer-aided design/computer-aided manufacturing (CAD/CAM) materials. The abutment-implant structures were randomly assigned into four groups (n=11 per group): bi-layered zirconia restorations (BL), translucent zirconia (4Y-PSZ) restorations (TZ), lithium disilicate ceramic restorations (LD), and dispersed nanoparticle-filled composite resin restorations (CM). All restorations were adhesively bonded to the titanium abutments. After the restoration-abutment complex was tightened onto the implant, the fracture strength was measured. The TZ (2.06 kN) and LD (1.87 kN) groups had significantly higher median fracture strengths than the BL (1.12 kN) and CM (1.10 kN) groups. In terms of fracture resistance, the 4Y-PSZ and lithium disilicate ceramic monolithic restorations would be superior to bi-layered 3Y-TZP and composite resin monolithic restorations for HACs in the premolar region.

Influence of the nanostructural characteristics of inorganic fillers on the physical properties of resin cements.

Light-curing resin cements, each comprising one of five different inorganic fillers (non-porous and porous spherical SiO2 particles, irregularly shaped glass and ZrO2 particles, and porous ZrO2 spheres), monomers, and polymerization initiators were prepared to determine the effect of filler morphology on the adhesive strength of the resin cement. The strength of adhesion to a computer-aided design/computer-aided manufacturing (CAD/CAM) resin block was investigated mechanically by measuring the tensile bond strength, flexural strength, and elastic modulus. The resin cement containing sub-micron porous ZrO2 spheres had significantly higher tensile bond strength than the other resin cements. The resin cement containing the porous ZrO2 spheres had markedly lower flexural strength and elastic modulus values than the resin cements containing SiO2 and glass fillers.

The influence of different storage media on Vickers hardness and surface roughness of CAD/CAM resin composites

IntroductionThis study examined Vickers hardness as well as surface characteristics of different computer-aided design/computer-aided manufacturing (CAD/CAM) resin composites prior to and after storage in various media.Materials and methodsCAD/CAM resin composite blocks (Grandio Blocs (GB), Lava Ultimate (LU), Brilliant Crios (BC), Cerasmart (GC), Shofu Block HC (SB), Tetric CAD (TC), Luxacam Composite (LC); incl. different translucency variants) were prepared, polished and surface free energy was determined. The specimens were divided into four groups: dry conditions for 24 h (25 °C), demineralized water (37 °C), Pepsi Cola (37 °C) and 75% ethanol (37 °C). After seven and 28 days of storage, Vickers hardness was determined. Surface roughness was measured after the entire storage period.Results and discussionVickers hardness was in the range of about 150 HV for GB, around 115 HV for LU, and 80–100 HV for BC, GC, SB, TC and LC. Only minor differences (total: 50.2 (6.4)–56.2 (3.2) mN/m) in surface free energy could be detected. No relationship was observed between surface free energy and filler content. However, a correlation between filler content and Vickers hardness was evident. Artificial aging caused a decrease of Vickers hardness (up to −40 HV or 35%) depending on storage media, duration and material. The changes in surface texture after immersion in different media were below a value of ΔSa = 0.015 µm.ConclusionArtificial aging of CAD/CAM resin composites leads to a significant decrease of Vickers hardness for most materials, while only small changes in surface roughness were identified.Graphical

Automated Subtractive Timber Manufacturing—Joinery Machines Versus Industrial Robots

AbstractA high degree of automation, especially through the use of robots, is state of the art in the automotive and electronics industries. Even though the construction sector is currently lagging behind, an increase in automation and the use of robots can be observed. To assess the potential in industrial timber construction with a focus set on subtractive machining, this paper presents the state of the art in terms of the use of industrial robots and joinery machines, compact joinery machines, and gantry-type joinery machines in regard to milling processes. The capabilities of different types of joinery machines are evaluated and compared with vertical articulated industrial robots equipped with machining spindles. An overview of the history and an assessment of various parameters in the categories: Quality, System, Machining and Economy, is given. Publications, manufacturer information, and industry findings are reviewed to answer pressing questions on automation in timber construction. Limitations such as robotic stability or the limited working space of joinery machines and the affordability of robotic systems are elaborated and CAD/CAM (computer-aided design/computer-aided manufacturing) processes are scrutinized. After the evaluation and comparison of four different systems, an approach for future research is proposed. The main findings are a very low degree of robotization and data availability within the timber industry, lower acquisition costs for industrial robots while increasing the flexibility of the workspace, and task-specific advantages of the respective systems, including machining power, potential for improvement in automation (especially CAD/CAM), and machining quality.

Fracture Resistance of Zirconia Restorations with Four Different Framework Designs.

Objectives: This study assessed the fracture resistance of zirconia crowns with four framework designs, fabricated by computer-aided design/computer-aided manufacturing (CAD/CAM) technology. Materials and Methods: In this experimental study, a maxillary central incisor was prepared and scanned with a CAD/CAM scanner, and 40 frameworks with 4 designs (N=10) were fabricated as follows: simple core, dentine core with a design similar to dentine, 3mm trestle design collar in the lingual aspect with proximal buttresses, and monolithic or full-contour. After porcelain applying and 20h immersion in distilled water (37°C), crowns were cemented on metal dies using zinc phosphate cement. Fracture resistance was measured by a universal testing machine. Data were analyzed with one-way ANOVA (alpha=0.05). Results: Fracture resistance was maximum in the monolithic group, followed by the dentine core, trestle design, and simple core groups, respectively. The mean fracture resistance of the monolithic group was significantly higher than that of the simple core group (P<0.005). Conclusion: Zirconia restorations with frameworks that provided higher and more support for porcelain, showed increased fracture resistance.

Effect of CAD/CAM Constructed BIOHPP versus Zirconia Frameworks Reinforced Maxillary Complete Denture on Fracture Resistance (In vitro Study)

Aim: this study was to investigate the effect of reinforcing material on the fracture resistances of Computer-aided design/computer-aided manufacturing (CAD-CAM) BIOHPP (Bio High Performance Polymer) and Zirconia-reinforced maxillary complete dentures under fatigue loading. Materials And Methods: BIOHPP and Zirconia framework-reinforced maxillary complete dentures were fabricated using silicone moulds and acrylic resin. A control group was prepared with no reinforcement (n =5 per group). After cyclic loading was applied using a chewing simulator, fracture resistance was measured by a universal testing machine. The fracture resistance was measured for each denture. Results: After cyclic loading, none of the dentures showed cracks or fractures. During fracture resistance testing, all unreinforced dentures experienced complete fracture. The framework-reinforced dentures showed fracture of the acrylic without framework fracture. BIOHPP reinforced maxillary denture showed the highest fracture resistance (1705.70±213.75), followed by the Zirconia reinforced maxillary denture (1690.10±135.40) (p&lt;0.001). Conclusion: CAD/CAM Zirconia and BIOHPP frameworks used as reinforcement for maxillary complete denture shows higher fracture resistance and more retentive dentures under cyclic loading. Maxillary complete denture reinforced by BIOHPP framework show higher fracture resistance than Zirconia. The BIOHPP and Zirconia-reinforced denture exhibits a fracture resistance higher than that of the unreinforced denture, with dentures maintaining their shape even after fracture, indicating the possibility of easier repair.

Comparison of bracket bonding between two CAD/CAM guided bonding devices: GBD-U vs GBD-B

ObjectiveTo compare the bracket bonding accuracy, efficiency, reproducibility, and three-dimensional (3D) printing duration of the computer-aided design/computer-aided manufacturing (CAD/CAM) unilateral contact guided bonding device (GBD-U) and the bilateral contact guided bonding device (GBD-B) in vitro. MethodsFive resin dental model sets were scanned and virtually bonded with brackets. GBD-U and GBD-B were designed and 3D printed for each model. GBD-Us had guide blocks that fit the occlusal sides of the bracket tie-wings, while GBD-Bs had guide arms that fit the occlusal and distal sides of the tie-wings. Five orthodontic residents were recruited to bond brackets on the same 3D-printed copies of resin models in a dental mannequin using GBD-Us and GBD-Bs, respectively. The time for 3D printing of GBDs and bracket bonding was recorded. The linear and angular deviations between the bonded brackets and the virtually bonded ones were measured. ResultsA total of 50 sets of resin models (1000 brackets/tubes) were bonded. The time for 3D printing and bracket bonding was shorter for GBD-Us (41.96 mins/6.38 mins) than for GBD-Bs (78.04 mins/7.20 mins). In both devices, 100% linear deviations and over 95% angular deviations were below 0.5 mm or 2°, respectively. Deviations in the mesiodistal dimension, torque, angulation, and rotation were significantly lower in the GBD-U group (P<0.01). High inter-operator reproducibility of bracket bonding was confirmed for both devices. ConclusionGBD-U was more time-efficient in 3D printing. Both GBDs showed clinically acceptable accuracy, whereas GBD-U had higher bonding accuracy in the mesiodistal dimension, torque, angulation, and rotation than GBD-B. Clinical SignificanceCAD/CAM GBD-U provides high bracket bonding accuracy in a time-efficient manner and has the potential to be clinically applied.

Evaluation of One- and Two-Step Impression Techniques and Vertical Marginal Misfit in Fixed Prothesis.

12 impressions were made of a resin maxillary model (second premolar and second molar) with two prepared abutment teeth using vinyl polysiloxane (VPS); the margin of the second premolar was 0.5 mm subgingivally; and the margin of the second molar tooth was at the level of the gingiva. Impressions were made using two techniques: one-step and two-step putty/light materials. A three-unit metal framework was fabricated on the master model using the computer-aided design/computer-aided manufacturing (CAD/CAM) technique. The vertical marginal misfit was evaluated in the buccal, lingual, and mesial and distal surfaces of the abutments on the gypsum casts using a light microscope. Data were analyzed using the independent t-test (α < 0.05). The results showed significantly lower vertical marginal misfit in all six areas evaluated around the two abutments in the two-step impression technique compared with the corresponding values in the one-step technique. Vertical marginal misfit in the two-step technique with a preliminary putty impression was significantly lower than in the one-step putty/light-body technique.

Digital Volumetric Analysis of CAD/CAM Ceramic Materials after Tooth Brushing

Objective: The objective of this in vitro study was to evaluate the volumetric wear of three CAD/CAM (computer-aided design/computer-aided manufacturing) ceramic materials. Materials and Methods: The materials evaluated were CEREC Blocs (Dentsply Sirona), Initial LRF (GC) and Amber Mill (HASS Corp). All the samples (n=30) were subjected to simulated brushing (100,000 cycles). The wear was assessed by superimposing pre- and post-brushing scans obtained with an intraoral optical scanner (CEREC Primescan; Dentsply Sirona, Germany), which was then imported into the OraCheck 5.0 software (Dentsply Sirona, Germany). Results: The CAD/CAM ceramic materials tested showed no statistically significant differences in terms of the average volumetric wear (p-= 0.455). Conclusion: Therefore, it can be concluded that the ceramic materials have a good behavior under simulated brushing, without significant volumetric alterations.

Evaluation of the Translucency Properties for CAD/CAM Full Ceramic Crowns Fabricated From Glass Ceramics (E.max) or High Translucency Zirconia (Lava Plus): A Clinical Study.

Introduction Nowadays, cosmetic demands are the first reason to visit dental clinic. However, most ceramic prostheses need an excessive removal of the dental structure, whether for full crowns or veneer preparation. With the innovation in ceramic materials, high translucent zirconia that demands minimal preparation with high aesthetic results was used for computer-aided design/computer-aided manufacturing (CAD/CAM) Full ceramic crown fabrication. The objective of this study was to compare the translucency properties of CAD/CAM full ceramic crowns fabricated from glass ceramics (E.max) and high translucency zirconia (Lava plus, 3M EPSE). Material and methods The sample consisted of 60 full ceramic crowns divided into two groups; the first group consisted of 30 IPS E.max CAD/CAM full ceramic crowns, while the second one consisted of 30 high translucent zirconia CAD/CAM full ceramic crowns. Translucency for both groups was evaluated directly after cementation by observing the blue light passing through the prostheses. Pearson Chi-Square test was used to study the difference in translucency between the two study groups. Results IPS E.max CAD showed a higher translucency compared to lava plus high translucency zirconia; in addition, this difference was statistically significant (p=0.028). Conclusion Within the limitation of this study, we found that the translucency of dental ceramic was affected by the ceramic material. As IPS E.max CAD was significantly higher in terms of translucency compared to High Translucent Zirconia.

Microgap Formation between a Dental Resin-Matrix Computer-Aided Design/Computer-Aided Manufacturing Ceramic Restorative and Dentin after Various Surface Treatments and Artificial Aging

The potential formation and the size of microgaps at the material/dentin interface after various surface modifications of a resin-matrix computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic following artificial aging was investigated. Fifty human third molars were used, and a resin-matrix CAD/CAM ceramic, Lava Ultimate, and a resin cement material, Rely X Ultimate, were tested. CAD/CAM blocks were sectioned, and each slab was luted on the tooth surface using the same resin cement. The surface material was modified using the following treatments: Group 1—no treatment (control); Group 2—hydrofluoric acid (HF) + silane; Group 3—air abrasion with Al2O3 particles (29 μm); Group 4—air abrasion with Al2O3 particles (53 μm); and Group 5—erbium, chromium:yttrium–scandium–gallium–garnet (Er,Cr:YSGG) (2780 nm) laser treatment. The specimens were submitted to thermocycling (5000 cycles: 5 °C–55 °C) and then transversely cut in the middle and examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Larger microgaps were observed in the control and laser-treated groups, with no significant differences (p = 0.452). By contrast, the other three groups presented lower microgap formation, and in some cases, no microgaps were detected. Air-abrasion groups exhibited the lowest microgap formation (p &lt; 0.05). Different surface modifications of the material presented significant differences in the formation of microgaps at the adhesive interface after artificial aging, implying differences in bond strengths among the groups. Air-abrasion pretreatments with Al2O3 particles presented more beneficial results regarding microgap formation.

First-Hand Experience and Result with New Robot-Assisted Laser LeFort-I Osteotomy in Orthognathic Surgery: A Case Report.

We report the world's first developer-independent experience with robot-assisted laser Le Fort I osteotomy (LLFO) and drill-hole marking in orthognathic surgery. To overcome the geometric limitations of conventional rotating and piezosurgical instruments for performing osteotomies, we used the stand-alone robot-assisted laser system developed by Advanced Osteotomy Tools. The aim here was to evaluate the precision of this novel procedure in comparison to the standard procedure used in our clinic using a computer-aided design/computer-aided manufacturing (CAD/CAM) cutting guide and patient-specific implant. A linear Le-Fort-I osteotomy was digitally planned and transferred to the robot. The linear portion of the Le-Fort I osteotomy was performed autonomously by the robot under direct visual control. Accuracy was analyzed by superimposing preoperative and postoperative computed tomography images, and verified intraoperatively using prefabricated patient-specific implant. The robot performed the linear osteotomy without any technical or safety issues. There was a maximum difference of 1.5 mm on average between the planned and the performed osteotomy. In the robot-assisted intraoperative drillhole marking of the maxilla, which was performed for the first time worldwide, were no measurable deviations between planning and actual positioning. Robotic-assisted orthognathic surgery could be a useful adjunct to conventional drills, burrs, and piezosurgical instruments for performing osteotomies. However, the time required for the actual osteotomy as well as isolated minor design aspects of the Dynamic Reference Frame (DRF), among other things, still need to be improved. Still further studies for final evaluation of safety and accuracy are also needed.