Effects of 16% Carbamide Peroxide on Optical Properties of Thermally Aged Monolithic CAD-CAM Glass Ceramics with Different Surface Treatments.

This study aimed to investigate the effects of 16% carbamide peroxide (CP) on the relative translucency parameter (RTP) and color stability of thermally aged CAD-CAM glass-ceramics with glazing or polishing. Three different CAD-CAM blocks-feldspathic (VM), lithium disilicate (IPS), and zirconia-reinforced lithium silicate ceramic (VS)-were used in this study. The specimens were divided into two groups (n=10) according to surface treatments (glazing or polishing). Bleaching treatment with 16% CP was applied to the thermally aged specimens. A spectrophotometer (VITA Easyshade Advance) was used to measure the CIE L*a*b*coordinates of the specimens on white and black backgrounds, and RTP and color difference (ΔE00) values were calculated. The surface topography of the specimens and the atomic weight of the elements were analyzed with scanning electron microscopy and energy-dispersive x-ray. The data were analyzed by using the two-way ANOVA test for ΔE00 values and two-way repeated measures ANOVA test for RTP and color parameters values (a=0.05) and the Tukey post-hoc test was used for multiple comparisons of the groups. RTP values were statistically influenced by material type, bleaching, and finishing technique, and the interaction among these factors was found to be significant (p<0.05). ΔE00 values were statistically influenced by material type, finishing technique, and the interaction among these factors was also found to be significant (p<0.05). IPS presented significantly lower RTP and ΔE00 values for both glazed and polished surfaces (p<0.05). 16% CP bleaching agent caused changes in translucency of aged VM and IPS at different levels. Glazed surfaces presented higher color stability in comparison to mechanically polished surfaces for VS (p<0.05).

Fabrication of a 3-dimensionally printed definitive cast for an obturator prosthesis by merging intraoral scan image with cone beam computed tomography data: A clinical report.

This clinical report focuses on the production of a 3-dimensionally printed definitive cast by using digital scans to fabricate an obturator prosthesis for a completely edentulous patient with a maxillary defect. A merged intraoral scanner image of the soft tissue anatomy of maxillary structures with volumetric data of the craniofacial hard and soft tissues obtained from a cone beam computed tomography scan was used to generate a virtual cast, producing the polyurethane definitive cast manufactured by using a 3-dimensional printer.

Effects of magnetic resonance imaging on the microleakage of five restorative materials: An in vitro study.

OBJECTIVE: The objective of this study was to assess the effects of 3 T magnetic resonance imaging (MRI) on the microleakage of 5 restorative materials. METHODS: In total, 100 maxillary molars were randomly assigned to 5 groups (n = 20) for restoration with 5 different materials: amalgam, light-cured glass-ionomer cement, feldspathic porcelain fused to metal, pressed lithium disilicate glass ceramic, and composite resin. In each group, 10 specimens were subjected to MRI, and 10 specimens served as controls with no MRI exposure. Standardized class V cavities were prepared with occlusal margins terminating in enamel and gingival margins terminating in dentin. Microleakage penetration at the enamel and dentin margins was calculated for each group. A chi-square test was used for intergroup comparisons. Statistical significance was established at P < .05. RESULTS: Microleakage penetration did not differ significantly between specimens subjected to MRI and the controls for any restoration (P ≥ .362 for the enamel margin, P ≥ .067 for the dentin margin) or between specimens treated with different restorative materials (P ≥ .355). No significant differences in microleakage were discovered between the enamel and dentin margins of any of the restorative groups (P ≥ .236). CONCLUSION: MRI had no effect on the microleakage of the 5 restorative materials.

Comparison of Flexural Strength of Different CAD/CAM PMMA-Based Polymers.

PURPOSE: To compare the flexural strength of different computer-aided design/computer-aided manufacturing (CAD/CAM) poly(methyl methacrylate)-based (PMMA) polymers and conventional interim resin materials after thermocycling. MATERIALS AND METHODS: Rectangular-shaped specimens (n = 15, for each material) (25 × 2 × 2 mm3 ) were fabricated from 3 CAD/CAM PMMA-based polymers (Telio CAD [T]; M-PM-Disc [M]; Polident-PMMA [P]), 1 bis-acrylate composite resin (Protemp 4 [PT]), and 1 conventional PMMA (ArtConcept Artegral Dentine [C]) according to ISO 10477:2004 Standards (Dentistry-Polymer-Based Crown and Bridge Materials). The specimens were subjected to 10,000 thermocycles (5 to 55°C). Three-point flexural strength of the specimens was tested in a universal testing machine at a 1.0 mm/min crosshead speed, and the flexural strength data (σ) were calculated (MPa). The flexural strength values were statistically analyzed using 1-way ANOVA, and Tukey HSD post-hoc test for multiple comparisons (α = 0.05). RESULTS: Flexural strength values ranged between 66.1 ± 13.1 and 131.9 ± 19.8 MPa. There were significant differences among the flexural strengths of tested materials, except for between T and P CAD/CAM PMMA-based polymers (p > 0.05). CAD/CAM PMMA-based polymer M had the highest flexural strength and conventional PMMA had the lowest (p < 0.05). CAD/CAM PMMA-based T and P polymers had significantly higher flexural strength than the bis-acrylate composite resin (p < 0.05), and conventional PMMA (p < 0.0001), and significantly lower flexural strength compared to CAD/CAM PMMA-based M (p < 0.05). CONCLUSIONS: The flexural strength of CAD/CAM PMMA-based polymers was greater than the flexural strength of bis-acrylate composite resin, which had a greater flexural strength compared to conventional PMMA resin.

In Vitro Evaluation of Adhesion of Candida albicans on CAD/CAM PMMA-Based Polymers.

PURPOSE: To compare the amount of adherent Candida albicans to different CAD/CAM poly(methyl methacrylate) (PMMA)-based polymers and conventional heat-polymerized PMMA after long-term thermal cycling. MATERIALS AND METHODS: The specimens were subjected to 10,000 thermal cycles (5-55°C) and divided into two groups, uncoated and pellicle-coated. Surface roughness and contact angles of the specimens were measured. The surface morphology was observed with scanning electron microscopy (SEM). An adhesion test was performed by incubating the disk specimens in C. albicans suspensions at 37°C for 2 hours, and the adherent cells were counted under an optical microscope. The data were analyzed statistically using a variance analysis and Tukey HSD post hoc comparison test. The correlation between measurements was tested using a Pearson correlation analysis (α = 0.05). RESULTS: CAD/CAM polymers generally showed statistically significant lowest Ra and contact angle values, whereas conventional PMMA showed the highest Ra and contact angle values in the uncoated group (p < 0.05). Pellicle coating essentially increased contact angle of all materials and reduced the differences in a number of Candida cells on the materials (p < 0.05). Candida adhesion was statistically significantly greatest on conventional PMMA when compared to CAD/CAM polymers. A strong positive correlation was found between the surface roughness of the specimens (p < 0.05) and the amount of adhered cells, whereas no correlation was found between hydrophobicity of the specimens and the amount of adhered cells (p > 0.05). CONCLUSIONS: CAD/CAM PMMA-based polymers may be preferable to reduce Candida-associated denture stomatitis in long-term use.

Fabrication of obturator prosthesis by fusing CBCT and digital impression data.

This clinical report describes a digital workflow using an intraoral digital impression and cone beam computed tomography (CBCT) volumetric data to create a three-dimensional (3D) virtual model of the dentition, defect area, and soft and hard tissue of a patient who had undergone a hemimaxillectomy. Stereolithography (SLA) 3D printing technology was used to produce a resin mold, from which an obturator prosthesis was fabricated through a conventional technique.

Evaluation of flexural strength and surface properties of prepolymerized CAD/CAM PMMA-based polymers used for digital 3D complete dentures.

PURPOSE: The objectives of this in vitro study were to evaluate the flexural strength (FS), surface roughness (Ra), and hydrophobicity of polymethylmethacrylate (PMMA)-based computer-aided design/computer-aided manufacturing (CAD/CAM) polymers and to compare the properties of different CAD/CAM PMMA-based polymers with conventional heat-polymerized PMMA following thermal cycling. MATERIALS AND METHODS: Twenty rectangular-shaped specimens (64 × 10 × 3.3 mm) were fabricated from three CAD/CAM PMMA-based polymers (M-PM Disc [M], AvaDent Puck Disc [A], and Pink CAD/CAM Disc Polident [P], and one conventional heat-polymerized PMMA (Promolux [C]), according to ISO 20795-1:2013 standards. The specimens were divided into two subgroups (n = 10), a control and a thermocycled group. The specimens in the thermocycled group were subjected to 5000 thermal cycling procedures (5 to 55°C; 30 s dwell times). The Ra value was measured using a profilometer. Contact angle (CA) was assessed using the sessile drop method to evaluate surface hydrophobicity. In addition, the FS of the specimens was tested in a universal testing machine at a crosshead speed of 1.0 mm/min. Surface texture of the materials was assessed using scanning electron microscope (SEM). The data were analyzed using two-way analysis of variance (ANOVA), followed by Tukey's HSD post-hoc test (α < 0.05). RESULTS: CAD/CAM PMMA-based polymers showed significantly higher FS than conventional heat-polymerized PMMA for each group (P < 0.001). CAD/CAM PMMA-based polymer [P] showed the highest FS, whereas conventional PMMA [C] showed the lowest FS before and after thermal cycling (P < 0.001). There were no significant differences among the Ra values of the tested denture base polymers in the control group (P > 0.05). In the thermocycled group, the lowest Ra value was observed for CAD/CAM PMMA-based polymer [M] (P < 0.001), whereas CAD/CAM PMMA-based polymers [A] and [P], and conventional PMMA [C] had similar Ra values (P > 0.05). Conventional PMMA [C] had a significantly lower CA and consequently lower hydrophobicity compared to the CAD/CAM polymers in the control group (P < 0.001). In the thermocycled group, CAD/CAM PMMA-based polymer [A] and conventional PMMA [C] had significantly higher CA, and consequently higher hydrophobicity when compared to CAD/CAM polymers [M] and [P] (P < 0.001). However, no significant differences were found among the other materials (P > 0.05). CONCLUSIONS: The FS and hydrophobicity of the CAD/CAM PMMA-based polymers were higher than the conventional heat-polymerized PMMA, whereas the CAD/CAM PMMA-based polymers had similar Ra values to the conventional PMMA. Thermocycling had a significant effect on FS and hydrophobicity except for the Ra of denture base materials.

Nerve damage assessment following implant placement in human cadaver jaws: an ex vivo comparative study.

The present study compared the use of cone beam computerized tomography (CBCT) images and intra-oral radiographs in the placement of final implant drills in terms of nerve damage to cadaver mandibles. Twelve cadaver hemimandibles obtained from 6 cadavers were used. Right hemimandibles were imaged using peri-apical radiography and left hemimandibles using CBCT, and the images obtained were used in treatment planning for the placement of implant drills (22 for each modality, for a total of 44 final drills). Specimens were dissected, and the distances between the apex of the final implant drill and the inferior alveolar neurovascular bundle and incisive nerve were measured using a digital calliper. Nerves were assessed as damaged or not damaged, and the Chi-square test was used to compare nerve damage between modalities (P < 0.05). Nerve damage occurred with 7 final drills placed based on peri-apical radiography (31.8%) and 1 final drill placed using CBCT images (4.5%). The difference in nerve damage between imaging modalities was statistically significant (P = 0.023), with CBCT outperforming intraoral film in the placement of final implant drills ex vivo. In order to prevent nerve damage, CBCT is recommended as the principal imaging modality for pre-implant assessment.

Radiofrequency heating and magnetic field interactions of fixed partial dentures during 3-tesla magnetic resonance imaging.

OBJECTIVE: This study evaluated the heating and magnetic field interactions of fixed partial dentures in a 3-Tesla (3T) magnetic resonance imaging (MRI) environment. STUDY DESIGN: Three substructure materials (Co-Cr, Ni-Cr, ZrO2) were used to fabricate twelve 4-retained bridges and 12 crowns. Specimens were evaluated at 3T for radiofrequency heating and magnetic field interactions. One-way analysis of variance (ANOVA) test was used to compare continuous variables of temperature change. Significance was set at P < .05. Translational attraction and torque values of specimens were also evaluated. RESULTS: None of the groups exhibited excessive heating (mean temperature change, < 1.4 °C), with maximum increase at the end of the T-1. Moreover, in all groups, only relatively minor magnetic field interactions that would not cause movement in situ were observed. CONCLUSION: The study findings indicated that patients with fixed partial dentures (single crown or bridge) fabricated from Co-Cr, Ni-Cr, and zirconia substructures may safely undergo MRI at up to 3T.

Rehabilitation of a patient with mandibular resection using osteointegrated implants: a case report.

This case report details a 65-year-old male patient who underwent mandibular resection and radiotherapy as treatment for squamous cell carcinoma of the right mandible. The patient was rehabilitated with an implant-supported fixed partial denture and a maxillary occlusal ramp. The patient has been wearing his prosthesis for 2 years with no complaints.

Enhanced retention of a maxillofacial prosthetic obturator using precision attachments: Two case reports.

The majority of maxillary defects can be rehabilitated with conventional simple obturator prosthesis. However, inadequate retention, stability and support may be associated with the use of an obturator. Precision attachments have been used to retain obturators for some time. The use of precision attachments in a dentate maxillectomy patient can yield significant functional improvement while maintaining the obturator's aesthetic advantages. This clinical report describes the prosthetic rehabilitation of two maxillary defects with an obturator retained using extracoronal resilient precision attachments.

Accuracy of a newly developed cone-beam computerized tomography-aided surgical guidance system for dental implant placement: an ex vivo study.

The aim of the present study was to measure the accuracy of the cone-beam computerized tomography (CBCT)- aided StentCad Beyond surgical guidance system and to compare bone-supported and tooth/bone-supported guidance by using this system in dental implant placement ex vivo. Five cadaver mandibles were scanned using an Iluma CBCT scanner. After scanning, DICOM slices were transferred to the StentCad Beyond implant simulation software, which was used for preoperative implant planning. Using the StentCad Beyond guidance system, 9 implant drills were inserted using a bone-supported guidance system and 11 using a tooth/bone-supported guidance system. Mandibles were scanned again and these data were transferred to the StentCad Beyond software. Pre- and postoperative information was superimposed using the Rhinoceros version 4 software program, and deviations between planned and actual drill positions were calculated for each implant. In addition, differences between bone-supported and tooth/bone-supported guidance systems were analyzed by t-test, with a significance level of P < .05. Data analysis found a mean coronal deviation of 1.2 ± 0.3 mm and 0.6 ± 0.6 mm, mean apical deviation of 1.3 ± 0.6 mm and 0.7 ± 0.6 mm, mean apical and coronal depth deviation of 1.4 ± 0.3 mm and 1.3 ± 0.3 mm, and mean angular deviation of 4.2° ± 2.0° and 3.0° ± 1.5° for tooth/bone supported and bone-supported guides, respectively. No statistical differences were found in depth or angular deviations between groups (P > .05); however, statistically significant differences between groups were found in mean horizontal coronal deviation (P = .016) and mean horizontal apical deviation (P = .047). The StentCad Beyond system was found to be a reliable guide for placing implants ex vivo.

Comparative assessment of subjective image quality of cross-sectional cone-beam computed tomography scans.

Since the introduction of cone-beam computed tomography (CBCT), several novel systems with different technical specifications and settings have become commercially available. Therefore, it is essential to evaluate CBCT systems for differences in the subjective quality of images obtained for various dental procedures. We evaluated the subjective image quality of cross-sectional scans obtained from various CBCT systems. Images of three cadaver mandibles were obtained from four different CBCT units: 1) Veraviewepocs 3D 40 × 40 mm field of view (FOV) (voxel size: 0.125 × 0.125 × 0.125 mm), 2) Iluma, low-resolution (voxel size: 0.3 × 0.3 × 0.3 mm), 3) Kodak, 50 × 3.7 cm FOV (voxel size: 0.076 × 0.076 × 0.076 mm), and 4) Vatech 12 × 8.5cm FOV (voxel size: 0.160 × 0.160 × 0.160 mm). We assessed subjective image quality and the visibility of 10 specific features, namely, caries, amalgam restoration, final implant drill, root canal filling, metal crown, mandibular canal, mental foramen, tooth (periodontal ligament space and lamina dura), trabecular pattern, and soft tissue. Images were viewed and scored by five calibrated observers, and image quality was ranked from best to worst. The Veraviewepocs 3D had the highest quality images for most of the assessed features, whereas the Iluma low-resolution scans were rated as the lowest quality images.

Prosthetic rehabilitation of a patient with bilateral cleft lip and palate using osseointegrated implants and extracoronal resilient attachments: a case report.

This case study reports on the prosthetic rehabilitation of a patient with an unrepaired bilateral cleft lip and palate using osseointegrated implants, extracoronal resilient attachments, a combination of metal-ceramic cement-retained fixed partial restorations, and removable prosthesis. Preoperative clinical examination of a 32-year-old woman with bilateral cleft lip and palate revealed a large oronasal communication, hyperplastic soft tissue surrounding the hard palate defect, and a severely resorbed alveolar ridge. A maxillary obturator prosthesis supported by implants and retained with an extracoronal resilient attachment was designed to cover the oronasal communication in the hard palate and fulfill the patient's functional and aesthetic requirements. The patient has been wearing the prosthesis for 1 year. Her speech quality has greatly improved, and her aesthetic and functional expectations have been met.

Occlusal caries detection by using a cone-beam CT with different voxel resolutions and a digital intraoral sensor.

OBJECTIVES: This study assessed in vitro the diagnostic ability of intraoral digital CCD sensor images and CBCT images at different voxel resolutions in the detection of occlusal caries. STUDY DESIGN: The study sample consisted of 130 mandibular molars (61 sound and 69 diseased). Digital intraoral images and CBCT images were obtained at 0.1-mm, 0.2-mm, and 0.3-mm voxel sizes. All images were evaluated separately by 4 observers, and evaluations were repeated after a 4-week interval. Weighted kappa coefficients were calculated to assess intra- and interobserver agreement for each image set, and scores were compared with the histological gold. For the estimation of nonparametric imaging modality effects and tests of hypotheses, SAS 9.0 and SAS macros were used for F1_LD_F1 factorial design. An a priori level of significance of P equals .05 was used. RESULTS: High intra- and interobserver agreements were obtained (Kappa value range: 0.825 to 0.948 for intraobserver agreement and 0.700 to 0.903 for interobserver agreement). Estimated relative treatment effects (RTE) ranged from 0.26 to 0.85, which varied with caries level and imaging modality. Differences between RTE values obtained with ultra-resolution and high- and low-resolution images were not statistically significant for all caries levels. Comparing 3D and intraoral imaging modalities among caries levels showed that imaging modality performance was different for deep enamel, superficial dentine, and deep dentine; however, imaging modality performance was not statistically different for healthy and superficial enamel caries groups. CONCLUSION: At all voxel sizes, CBCT images can be considered a tool for use in the diagnosis of occlusal caries.

The effects of digital image enhancement on the detection of vertical root fracture.

AIM: To determine the effects of digital image enhancement on observer ability to detect experimentally induced vertical root fractures (VRF). MATERIAL AND METHODS: A total of 64 extracted human mandibular premolar teeth were used in this study. In 32 teeth, VRFs were created in the bucco-lingual planes by gently tapping with screw-type root-canal pins. The remaining 32 intact teeth served as a control group. Digital images were obtained using a charge coupled device sensor. Three observers separately examined the original and four types of digitally enhanced images (enhanced using sharpness, zoom-in, reverse-contrast, and pseudo-3D functions) at 1-week intervals. All teeth were evaluated using a 5-point scale for the presence/absence of VRF. Evaluations of each image set were repeated 1 month after the initial viewings. Kappa coefficients were calculated to investigate the degree of intra- and inter-observer agreement. The areas under the receiver operating characteristic (ROC) curves (Az values) were calculated using the MedCalc statistical software. ROC values for each image type, observer and viewing were compared using t-tests. A level of alpha = 0.05 was considered significant. RESULTS: Kappa coefficients for intra-observer agreement ranged from 0.304 to 0.679. Inter-observer agreement kappa values ranged from 0.109 to 0.399 for the first reading and from 0.106 to 0.380 for the second reading. Statistical comparisons between Az values for each observer showed no significant differences (P > 0.05) among image types. CONCLUSION: There were no differences in diagnostic outcomes among differently enhanced images in the in vitro detection of VRF.

Detection of vertical root fracture using cone-beam computerized tomography: an in vitro assessment.

OBJECTIVES: This study aimed to compare 2 cone-beam CT units [NewTom 3G (small FOV), Iluma (ultra/low resolution)] and an intraoral CCD sensor in the detection of vertical root fracture (VRF). STUDY DESIGN: The VRFs were created in 30 teeth, and 30 intact teeth served as control samples. All images were evaluated twice by 4 observers. Kappa coefficients were calculated to assess intra- and interobserver agreement, and t tests were used to compare Az values (alpha = 0.05). RESULTS: Both intra- and interobserver agreement values were higher for the ultra-resolution Iluma and NewTom 3G images compared with the low-resolution Iluma and intraoral CCD images. Az values for the ultra-resolution Iluma and NewTom 3G images were also higher than for the Iluma low-resolution and intraoral CCD images. No significant differences (P > .05) in diagnostic accuracy were found between the Iluma ultra-resolution and NewTom 3G images, with the exception of the second reading of observer 2 (P = .036), and no significant differences (P > .05) were found between the intraoral digital and low-resolution Iluma images. CONCLUSION: Both ultra-resolution Iluma and NewTom 3G images performed better than low-resolution Iluma and intraoral CCD images in the detection of VRF.