Ceramic veneer shade evaluation using a multicolored 3D-printed model-A case report.

OBJECTIVE: This article demonstrates the use of a multicolored 3D-printed model for laboratory shade evaluation of ceramic veneers. CLINICAL CONSIDERATIONS: A young female patient presented with peg lateral incisors and diastemata between her maxillary incisors. Four ceramic veneers for her maxillary incisors were fabricated using a digital workflow. A multicolored 3D-printed model was manufactured using material jetting technology. The multicolored model and try-in pastes were used to evaluate and adjust the shade of the veneers. Clinically acceptable color matching was achieved, the veneers were delivered without further chairside shade adjustments. CONCLUSIONS: Successful color evaluation and adjustment were achieved using the combination of multicolored 3D-printed model and try-in pastes. The use of this approach saved time for stump shade taking and fabrication of tooth-colored dies. CLINICAL SIGNIFICANCE: A multicolored 3D-printed model can be a useful tool for color evaluation and adjustment of ceramic restorations.

Effect of finish line location and saliva contamination on the accuracy of crown finish line scanning.

PURPOSE: Intraoral scanners are used widely as an alternative to conventional impressions, but studies on the influence of finish line location and saliva contamination on scanning trueness are lacking. The purpose of this in vitro study was to evaluate the influence of finish line location and saliva contamination on the scanning trueness of crown finish lines. MATERIALS AND METHODS: Three ivorine teeth were prepared for all-ceramic crowns with finish lines placed equigingivally, 0.5 mm subgingivally, and 1.0 mm subgingivally. A single-cord technique was used for gingival retraction, and a total of 180 intraoral scans were made using two intraoral scanners (Emerald; Planmeca USA Inc., Hoffman Estates, IL, USA & Trios 3; 3Shape A/S, Copenhagen, Denmark). The prepared teeth were separated from the dentoform and scanned using the same intraoral scanners to create reference scans. All scans were imported to the design software (Dental System 2019; 3Shape A/S, Copenhagen, Denmark). After marking the finish lines of prepared teeth, intraoral scans were aligned to the reference scans for comparisons. Vertical and horizontal marginal discrepancies were measured at four different measuring points (buccal, lingual, mesial, and distal) and analyzed. Two-way ANOVA and Tukey HSD tests were used for statistical analysis (α = 0.05). RESULTS: The average vertical and horizontal discrepancies from various groups ranged from -33 to 440 µm. For both intraoral scanners, subgingival finish line groups showed greater vertical and horizontal discrepancies compared with equigingival finish line groups. Saliva contamination significantly increased both vertical and horizontal discrepancies for all finish line locations. The discrepancy increases due to saliva contamination were greater for the subgingival groups. CONCLUSIONS: Subgingival finish lines were not accurately captured using the intraoral scanners. The presence of saliva significantly reduced scanning trueness, and this was amplified when the finish lines were located subgingivally.

Trueness of 3-dimensionally printed complete arch implant analog casts.

STATEMENT OF PROBLEM: Although a completely digital workflow has numerous advantages, a physical definitive cast may be especially helpful for the accurate assembly of components of complex complete arch-fixed prostheses, the evaluation of esthetic and occlusion features, or prosthesis fabrication. Research on the accuracy of additive complete arch casts with implants positioned with a large anterior-posterior (A-P) spread is sparse. PURPOSE: The purpose of this in vitro study was to evaluate the trueness of complete arch 4-implant analog casts with a large A-P distribution fabricated with different 3-dimensional (3D) printers. MATERIAL AND METHODS: Ten systems were evaluated representing currently available printing technologies and materials for the additive fabrication of complete arch 4-implant analog casts and compared for deviations in the X-, Y-, and Z-axes from the master model scan (MMS), recorded in standard tessellation language (STL). The MMS was provided to the laboratory selected by the manufacturer, permitting them to create their specific cast with computer-aided design and computer-aided manufacture specific to a particular system, including analog receptacle offset settings. Laboratories fabricated N=10 casts and affixed analogs. A conventional splinted impression and stone cast (CON) was fabricated as a control. The casts were scanned with a precision laboratory scanner (D2000; 3Shape A/S), and files were imported into the Convince metrology software program (3Shape A/S) for comparison with the MMS for mean deviations in the X-, Y-, and Z- axes. A 2-way ANOVA and the Tukey HSD comparison tests were performed between system groups and the 4 implant locations (α=.05). Comparative color maps were used to determine dimensional changes of the edentulous ridges. RESULTS: For 2-dimensional deviations from the MMS in each of the 3 axes, the printer type, implant location, and interaction between those 2 variables were found to be statistically significant (P<.05). Comparisons among printers showed the smallest deviations for Asiga Pro 4K (ASG) and Stratasys Origin One (ORI) printers in both the X- and Y-axes and for CON in the Z-axis. For 3D deviations, comparison among printers indicated that ORI, SprintRay Pro55 S (SPR), and Ackuretta SOL (ACK) had the largest deviations, whereas CON and ASG showed the smallest deviations. Comparison color mapping demonstrates a disparity between printed model dimensional changes and implant analog positioning since the color maps of the casts' ridge crests were not in concordance with the results of the implant analog deviations. CONCLUSIONS: ASG, 3D Systems ProJet MJP 2500 Plus (MJP), 3D Systems NextDent 5100 (NEX), Stratasys J5 DentaJet (PJ5), Ivoclar PrograPrint PR5 (PR5), and Prodways ProMaker LD20 (PWY) were similar in terms of 3D deviations to the conventional stone cast control. Comparative color mapping showed the direction and quantity of the dimensional changes of the ridge crest frequently did not correlate with the 3D deviations of implant analog positioning. Implant analog insertion errors were predominantly responsible for analog position 3D deviations rather than the polymerization shrinkage of additive photopolymers.

Wear pattern-associated color stability of prefabricated composite veneers versus ceramic veneers.

PURPOSE: To evaluate the effect of different surface wear patterns on the discoloration tendency of two different prefabricated composite veneers and lithium disilicate ceramic veneers. MATERIALS AND METHODS: Discoloration tendency of two prefabricated composite resin veneers (Visalys Veneer Chairside (VIS) and Componeer (COM)) were compared to lithium disilicate veneers (IPS) in vitro. For each material, n = 60 samples were allocated to different test groups, and therefore each n = 10 specimens per group went through different wear tests. Mechanical abrasion tests were conducted using a toothbrush simulator, while erosive effects were carried out by citric acid (pH 1.57). A combination of abrasion and erosion tests was conducted as well. Four groups of wear tests were implemented: (1) abrasion, (2) abrasion followed by erosion, (3) erosion, and (4) erosion followed by abrasion. Another group was stored in distilled water as the control and one group was stained without a prior wear test. The staining solution was made from a coffee-tobacco brew. Specimens were stored in the coffee-tobacco solution for 21 days. Color measurements were performed with VITA Easyshade. To evaluate intramaterial discoloration, one half of every specimen was protected with foil. After storage in the staining solution, the first measurement was carried out on the 'protected' (untreated) surface, followed by a second measurement on the 'processed' (treated) discolored surface. Euclidean distance (ΔE) of discoloration was calculated according to the CIE-L*C*h* system. Data were analyzed with ANOVA followed by Games-Howell post hoc test and paired t-test (α = 0.05). RESULTS: Highest changes in ΔE were found in COM after 'abrasion' (ΔE -2.55) and 'erosion followed by abrasion' (ΔE -1.41). The discoloration tendency of VIS was affected by all wear tests, but changes were below the perceptive threshold (ΔE -0.19-0.32). Only abrasion followed by erosion affected the discoloration of IPS significantly, but findings were below the perceptive threshold, as well (ΔE -0.09). CONCLUSIONS: Prefabricated composite resin veneers revealed a low level of discoloration tendency after different wear tests. Nevertheless, in most cases the lowest discoloration tendency was found in specimens made from lithium disilicate.

Accuracy of merging scans of definitive fixed prosthodontic impressions to obtain single, accurate digitized master casts.

PURPOSE: Many elastomeric impressions sent to commercial laboratory dental technicians may include marginal defects. To fabricate accurate restorations, digital technology may be used to merge digital files of defective impressions into a single standard tessellation language (STL) file free of errors. This would save clinicians and patients time and may improve clinical care. The purpose of this study was to compare the accuracy of digital master casts reconstructed from merged STL files of defective impressions with the file of the original defect-free preparations. MATERIAL AND METHODS: Ivorine teeth on a dentoform were prepared to receive a posterior fixed dental prosthesis (FDP) with complete coverage preparations. An impression was made in a stock tray using polyvinyl siloxane (PVS) impression material and an extraoral scanner (E3, 3Shape, Denmark) was used to digitize the impression; this was the reference cast. Wax was used to create defects on the buccal and lingual margins of the preparations. Fifteen PVS impressions were made of the FDP preparations with defects in the mesial and distal margins; another set of 15 PVS impressions was made of FDP preparations with defects in the buccal and palatal margins for a total of 30 impressions. All impressions were digitized using the same extraoral scanner (E3, 3Shape, Denmark). Corresponding STL files were paired and merged, and a master cast was created by eliminating the defects using the scanned data. This master cast was compared to the reference cast using reverse engineering software (Geomagic, Morrisville, NC, USA). The results were expressed as average errors and standard deviations in the master casts relative to the reference cast. To account for the presence of positive and negative values in the data set, in terms of errors, the root mean square (RMS) value was calculated for each sample. RESULTS: The mean average error in the sample was -0.4 µm. The average upper limit of 95% confidence interval was +36.5 µm, while the average lower limit of 95% confidence interval was -37.3 µm. The mean RMS of the errors found was 18.9 µm. CONCLUSIONS: The results of this study indicated that merging digitized definitive impressions to correct marginal defects resulted in master casts with a high level of accuracy relative to the reference cast.

Shear bond strength characteristics on surface treatment modalities of CAD-CAM resin polymers.

PURPOSE: The purpose of this in vitro study was to analyze the shear bond strength of composite resin to a commercially available high-performance polymer material for fixed, screw-retained full arch restorations. MATERIAL AND METHODS: A total of 135 computer-aided design and computer-aided manufacturing, high-performance polymer (HPP) blocks were cut and obtained from discs (Trilor 95, Harvest Dental, Brea, CA). The samples were 10 mm × 10 mm × 10 mm. The specimen surfaces were grouped as untreated (Group A), 50 µm Al2O3 (Group B), 110 µm Al2O3 (Group C), Rocatec (3 M, St. Paul, MN) activated with silica-modified alumina oxide treatment (Group D); and trimmed coarsely with a carbide bur (Group E). Group A samples were used as controls. After surface treatments, the specimens were gently cleansed with oil-free steam and alcohol wipes. Surface conditioning was performed on all physically treated samples.  The manufacturer's recommendations were followed for bonding composite resin to the samples with light-cured Visio.link (Bredent, Chesterfield, UK). Cylinders were veneered with composite resins (diameter 5 mm, height 4 mm) and polymerized on the specimen surfaces through plastic tubes. Twenty-seven specimens were used for each testing group and aging tests were performed. The experimental samples were thermocycled.  Shear bond strength and scanning electron microscopic tests were performed. Means and standard deviations were calculated.  Statistical analysis was performed with post-hoc Tukey tests. RESULTS: Statistical analysis revealed that there was a significant difference between the groups (p<0.001). The highest shear bond strengths were achieved for the specimens bonded with Visio.link without physical surface treatments (270.47 MPa). The lowest bond strengths were found for specimen surfaces abraded with 110 µm Al2O3 (117.03 Mpa) CONCLUSIONS: The results of this laboratory study indicated that the specimens used with Visio.link as provided by the manufacturer had the highest shear bond strengths between the composite resin and high-performance polymer test specimens. Modifications of the high-performance polymer surfaces with carbide burs did not change bonding strengths with the composite materials.

Precision and trueness of computer-assisted implant placement using static surgical guides with open and closed sleeves: An in vitro analysis.

OBJECTIVES: The aim of this in vitro study was to determine accuracy defined by trueness and precision of computer-assisted implant surgery comparing two guided surgery kits designed for either closed sleeves or open sleeves with a lateral window. MATERIAL AND METHODS: Each n=20 implants were placed fully guided (sleeve-bone distance of 2 or 4 mm) in identical replicas using a surgical guide with both closed sleeve or an open sleeve, partially guided, or free hand. The achieved implant position was digitized and compared with the planned position. Trueness and precision were determined. The angular deviation was defined as the primary outcome parameter. The means, standard deviation, and 95%-confidence intervals were analyzed statistically with 1-way ANOVA and the Scheffé procedure. RESULTS: The accuracy of guided implant placement using closed and open sleeves was comparable when the sleeve-bone distance was 2 mm. Accuracy decreased when the sleeve-bone distance increased in both fully guided groups, more so in the open than in the closed sleeve group. The least accurate method was the free-hand group. Partially guided implant surgery was more accurate than free-hand placement, but less accurate than the fully guided groups with 2-mm sleeve-bone distance. CONCLUSIONS: The closer the sleeve to the bone, the more accurate and precise is computer-assisted implant surgery using a closed system and a system using open sleeves. Partially guided implant surgery using only the static guide for the pilot drill is less accurate than both fully guided approaches, but more accurate than free-hand surgery.

Effect of scanning speed, scanning pattern, and tip size on the accuracy of intraoral digital scans.

STATEMENT OF PROBLEM: Currently available intraoral scanning technology makes intraoral scanning quicker and allows the use of smaller scanner tips. However, studies on the influence of scanning speed, tip size, and scanning patterns on scanning accuracy are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effect of scanning speed, scanning pattern, and scanner tip size on scanning trueness and precision. MATERIAL AND METHODS: A total of 120 complete arch intraoral scans were made with an intraoral scanner (Emerald). The 3 variables were tip size (small and regular), scanning pattern (occlusal first and S-shaped), and scanning speed (slow, regular, and fast). Ten scans for each variable combination were made and exported as standard tessellation language (STL) files. A laboratory scanner (E4) was used for the reference scan. The exported images were analyzed with an image analysis software program (Geomagic Control X). Root-mean-square deviation (RMSD) values between the intraoral scans and the reference scan were calculated to assess trueness. RMSD values between each intraoral scan were calculated to assess precision. Three-way analysis of variance (ANOVA) was used to evaluate the influence of each variable, and Tukey HSD tests were used for multiple comparisons (α=.05). RESULTS: For trueness evaluation, tip size was the only significant factor (P<.001). The scans made with a smaller tip showed lower trueness than the scans made with a regular tip. For precision evaluation, all 3 variables, tip size, scanning speed, and scanning pattern, had significant influence (P≤.001). The use of a small tip, fast scanning speed, and S-shaped scanning pattern made intraoral scanning less precise. CONCLUSIONS: The use of a small scanner tip negatively affected both trueness and precision. Fast scanning speed and S-shaped scanning pattern produced scans with lower precision than regular or slow scanning speed and the occlusal-first scanning pattern.

Dentogingival display through lip border movements: Report of the Committee on Research in Fixed Prosthodontics of the American Academy of Fixed Prosthodontics.

STATEMENT OF PROBLEM: Dentists strive to create natural looking teeth for their patients. However, much of the research on esthetic dentistry has used artificial and computer-generated images to establish esthetic norms. Altered images are helpful in determining personal preferences but may be misleading for natural norms. PURPOSE: The purpose of this report from the Committee on Research in Fixed Prosthodontics of the American Academy of Fixed Prosthodontics was to establish an evidence base for clinical guidelines on lip mobility and the visibility of oral tissues. MATERIAL AND METHODS: A systematic search was conducted to collect data on the lip border movements and the visibility of teeth and gingiva of human participants. RESULTS: One thousand and ninety-six articles were processed, and, based on inclusion criteria, 48 articles were reviewed. The findings determined that the upper lip lengthens with age resulting, at rest, in less display of the maxillary teeth and more of the mandibular arch. When evaluating the maxillary incisal edge position at rest, the canines are the most reproducible. Women tend to display more gingiva in a social smile than men, but this may not be so for a true smile of joy. Both the middle and lower facial thirds should be evaluated to detect a maximal smile. Care must be taken not to classify a person incorrectly as having a low smile line because they could still have a potential to show gingiva. CONCLUSIONS: Evidence-based clinical guidelines are offered to reduce the risk of esthetic failures.

Precision and trueness of implant placement with and without static surgical guides: An in vitro study.

STATEMENT OF PROBLEM: Malpositioning of implants is one of the main factors leading to hard- and soft-tissue deficiencies. Whether static computer-guided implant placement increases accuracy and prevents malpositioning is unclear. PURPOSE: The purpose of this in vitro study was to determine accuracy defined by trueness and precision (according to International Organization for Standardization 5725) of computer-assisted implant surgery (fully guided and partially guided) in comparison with freehand single implant placement. MATERIAL AND METHODS: Implants (n=20) were placed fully guided (sleeve-bone distance of 2, 4, or 6 mm), partially guided (guide used for pilot drill), or free hand in identical replicas produced from a cone beam computed tomography (CBCT) scan of a partially edentulous patient. The achieved implant position was digitized by using a laboratory scanner and compared with the planned position. Trueness (planned versus actual position) and precision (difference among implants) were determined. The 3D-offset at the crest of the implant (root mean square between virtual preoperative planning and postoperative standard tessellation language file) was defined as the primary outcome parameter. The means, standard deviation, and 95% confidence intervals were analyzed statistically with 1-way ANOVA and the Scheffé procedure. RESULTS: Fully guided implant surgery achieved significantly lower 3D deviations between the planned and actual implant position with 0.22 ±0.07 mm (2-mm sleeve-bone distance) than partially guided 0.69 ±0.15 mm and freehand placement 0.80 ±0.35 mm at the crest (P<.001). The distance among the implants in each group was again lowest in the fully guided group and highest in the freehand group. CONCLUSIONS: The static computer-assisted implant surgery showed high trueness and precision. The closer the sleeve to the bone, the more accurate and precise the method. Freehand implant placement was less accurate and precise than computer-assisted implant surgery (partially or fully).

Comparison of Wear Resistance of Prefabricated Composite Veneers Versus Ceramic and Enamel.

PURPOSE: To measure surface roughness before and after wear-tests of two different prefabricated composite veneers and compare them to ceramic veneers and human dental enamel. MATERIALS AND METHODS: Roughness (Ra-values) of two prefabricated composite veneers (Visalys Veneer Chairside (VIS) and Componeer (COM)) were compared to lithium disilicate Veneers (e.max CAD) and dental enamel (DENT) in vitro. In total n = 45 specimens per material and enamel samples were used for wear-tests. Wear-out tests were conducted by abrasion tests with a toothbrush simulator (22,000 strokes/ 100 g load; approximately equal to two years of cleansing) and erosion tests were carried out using citric acid (pH 1.57). Ra- and Sa-values were detected by white light interferometer before and after wear-tests. Data were analyzed with ANOVA followed by Games-Howell post hoc test and t-test (α = 0.05). RESULTS: At baseline the lowest Ra- and Sa-values were found in VIS (Ra: 0.01 µm; Sa: 0.04 µm) while DENT revealed significantly higher surface roughness (Ra: 0.11 µm, p < 0.05; Sa: 0.30, p = 0.186). COM had significantly higher Ra-values (Ra: 0.10 µm; Sa: 0.22 µm) after abrasion, while e.max CAD was most resistant to the treatments (Ra: 0.01 µm, p < 0.05; Sa: 0.05 µm, p < 0.05). Compared to DENT all veneers were significantly less affected by citric acid (p < 0.001). CONCLUSIONS: Prefabricated composite veneers have demonstrated less wear after abrasion and erosion tests compared to DENT, nevertheless, they revealed more wear compared to e.max CAD.

Effect of finish line design and metal alloy on the marginal and internal gaps of selective laser melting printed copings.

STATEMENT OF PROBLEM: Selective laser melting (SLM) technology has been introduced for printing metal dental restorations from Co-Cr base alloys or Au-Pt high noble alloys. However, information regarding the fit of restorations fabricated by using this technique is limited. PURPOSE: The purpose of this in vitro study was to determine the effect of 3 different finish line designs on the marginal and internal gaps of metal copings made from a base (Co-Cr), high noble (Au-Pd-Ag), and noble alloy (Co-Pd) by using the SLM technology. MATERIAL AND METHODS: Three Ivorine right maxillary central incisors were prepared with a chamfer, deep chamfer, or shoulder finish line. The preparations were scanned by using a TRIOS scanner, and a total of 90 dies were printed using DPR 10 Resin (30×3 finish line designs). Ten SLM copings were fabricated for each margin design and metal alloy combination for a total of 90 copings (10×3 finish line designs×3 alloys). Copings were cemented onto dies using an autopolymerizing composite-resin luting material. All coping-die assemblies were sectioned buccolingually by using a low-speed diamond saw, and images were obtained by using an inverted bright field metallurgical microscope at ×100 magnification. Marginal and internal gaps were measured at 5 locations: buccal margin, midfacial, incisal, midlingual, and lingual margin. After gap measurements, representative specimens were embedded in autopolymerizing resin and prepared for metallographic examination. A 2-way multivariate analysis of variance (MANOVA) was conducted to determine the overall significance, followed by ANOVA for each dependent variable (α=.05). RESULTS: The results indicated that alloy type and finish line had a significant influence on marginal gap of copings (P<.001). Relative to the internal gap, alloy type had a significant effect (P<.001), but the type of finish line had no statistically significant influence (P=.337). No statistically significant interactions occurred. Base alloys were printed with almost no observable porosity, whereas noble and high noble alloys exhibited hot tears and porosity. CONCLUSIONS: Thefinish line type did not influence the internal gap between copings and dies, whereas the alloy type influenced the marginal gap between copings and dies. SLM-fabricated Co-Cr copings on teeth prepared with a deep chamfer finish line demonstrated the lowest marginal gap.

The Effect of Temporary Cement Cleaning Methods on the Retention of Crowns.

PURPOSE: To evaluate the effect of temporary cement cleaning methods on the retention of cemented crowns using zinc phosphate cement and resin-modified glass ionomer cement. MATERIALS AND METHODS: Forty titanium specimens were fabricated to simulate prepared molars with minimally retentive taper. The Ni-Cr cast crowns were fabricated, temporarily cemented, and separated. The specimens were divided into four groups according to the temporary cement cleaning method (n = 10) as follows: control group (no temporary cementation), orange solvent group, ultrasonic cleaning group, and air-abrasion group. After the cleaning procedures, the specimens were cemented with definitive cements (zinc phosphate cement and resin-modified glass ionomer, RMGI, cement) and subjected to thermocycling (5000 cycles, 5-55°C, dwell time, 10 seconds). The tensile bond strength of each specimen was measured using a universal testing machine, and the results were analyzed using the Kruskal-Wallis and Mann-Whitney U test (α = 0.05). RESULTS: When cemented with zinc phosphate cement, the statistical analysis showed that the value of the air-abrasion group was significantly higher than those of the other groups (p < 0.01). There was no statistically significant difference among the other groups. When cemented with RMGI cement, the air-abrasion group showed the lowest value, and the control group showed the highest value (p < 0.01). The difference between the ultrasonic cleaning group and the orange solvent group was not statistically significant. CONCLUSION: The use of temporary cement did not have a significant influence on retention of permanently cemented crowns when zinc phosphate cement was used for permanent cementation. Airborne-particle abrasion after provisional cementation improved retention of crowns cemented with zinc phosphate cement; however, the use of temporary cement significantly decreased retention of permanently cemented crowns when RMGI cement was used regardless of the temporary cement cleaning method.

Do Class III patients have a different growth spurt than the general population?

INTRODUCTION: Understanding the timing and length of the growth spurt of Class III prognathic patients is fundamental to the strategy of interceptive orthopedic orthodontics as well as to the timing of orthognathic surgery. Consequently, this study was undertaken to determine whether there are any significant differences in the stature growth pattern of Class III subjects compared with non-Class III subjects and the general population. METHODS: Twelve-year longitudinal stature growth data were collected for 402 randomly selected adolescents in the general population, 55 Class III mandibular prognathic patients, and 37 non-Class III patients. The growth data were analyzed by using the traditional linear interpolation method and nonlinear growth functions. The 6 stature growth parameters were measured: age at takeoff, stature at takeoff, velocity at takeoff, age at peak height velocity, stature at peak height velocity, and velocity at peak height velocity. Comparisons in the stature growth parameters and 15 cephalometric variables among the general population, Class III subjects, and non-Class III subjects were made with multivariate analysis. RESULTS: Patients with Class III prognathism did not have different growth parameters compared with Class II subjects or the general population. CONCLUSIONS: This study does not allow meaningful conclusions with regard to the relationship of mandibular size and stature growth pattern. The application of nonlinear growth curves vs the traditional linear interpolation method was also discussed.

Digital Technologies for Restorative Dentistry.

Although the accuracy of direct digitization of oral structure has been improved, indirect digitization is still required in specific situations such as full-arch scanning. Once accurate images are imported, efficient designing can be achieved by CAD software. Although smile design using a 3-dimensional facial scan better predicts planned restorations, further improvement in virtual articulators is needed for complex cases. Computer-aided manufacturing can be offered in several formats such as chairside, laboratory, or centralized fabrications. The subtractive technique is mainly used for restorations, and many chairside CAM materials are available now, but the additive technique has the potential to save materials and an advantage in fabricating complex geometries. Limited evidence is available in applying CAD/CAM technologies in implant restorations. However, it is used to fabricate custom implant abutments and crowns from various materials such as titanium, zirconia, and PEEK and hybrid crowns using stock titanium base abutments.

A Fully Digital Workflow to Achieve Predictable Esthetic and Functional Outcomes: A Case Series.

Various types of digital dental technologies have been successfully implemented as a part of dental treatment to improve predictability and efficiency of dental procedures. Virtual smile design can be used to enhance predictability from an esthetic perspective, and the virtual articulator can be a useful tool to create a desired occlusal scheme. This case series describes a fully digital workflow that can predictably achieve desired esthetic and functional outcomes. The proposed protocol also includes other currently available digital technologies, such as intraoral scanning, computer-aided design, milling, and 3D printing. Three clinical cases are presented to describe the workflow in detail.

Early stature prediction method using stature growth parameters.

BACKGROUND: The creation of an accurate growth prediction method for human stature at a stage of growth has been an interesting challenge in medical science and human biology. AIM: The aim of this study was to develop a non-radiographic final stature prediction method that is applicable in the early pubertal growth period. SUBJECTS AND METHODS: Randomly selected 12-year serial stature growth data for 400 Koreans were fitted with two nonlinear growth curves: Preece and Baines model 1 (PB1) and Jolicoeur-Pontier-Pernin-Sempe (JPPS) functions. Five biological parameters, including take-off (TO) related parameters, were derived by differentiation of the two curves, respectively. Those five variables were composed into a multiple linear regression equation for final stature prediction. In the cross-validation subjects, TO-related variables were estimated by linear interpolation from the partial growth data prior to estimation age, then incorporated into the prediction equation. RESULTS: The final stature prediction model had excellent validity and accuracy when applied to the cross-validation samples. Prediction accuracy increased according to increasing years after take-off. CONCLUSIONS: This study suggests that a final stature prediction method using multiple regression analysis that includes biological parameters can predict stature growth with sufficient validity and accuracy. Incorporation of TO-related parameters allowed us to develop earlier growth evaluation and prediction methods compared with other previous methods.

Evaluation of shear bond strengths of gingiva-colored composite resin to porcelain, metal and zirconia substrates.

PURPOSE: The purpose of this study is to evaluate and compare the shear bond strength of the gingiva-colored composite resin and the tooth-colored composite resin to porcelain, metal and zirconia. MATERIALS AND METHODS: Sixty cylindrical specimens were fabricated and divided into the following 6 groups (Group 1-W: tooth-colored composite bonded to porcelain, Group 1-P: gingiva-colored composite bonded to porcelain, Group 2-W: tooth-colored composite bonded to base metal, Group 2-P: gingiva-colored composite bonded to base metal, Group 3-W: toothcolored composite bonded to zirconia, Group 3-P: gingiva-colored composite bonded to zirconia). The shear bond strength was measured with a universal testing machine after thermocycling and the failure mode was noted. All data were analyzed using the two-way analysis of variance test and the Bonferroni post-hoc test at a significance level of 0.05. RESULTS: The mean shear bond strength values in MPa were 12.39, 13.42, 8.78, 7.98, 4.64 and 3.74 for Group 1-W, 1-P, 2-W, 2-P, 3-W and 3-P, respectively. The difference between the two kinds of composite resin was not significant. The shear bond strength of Group 1 was the highest and that of Group 3 was the lowest. The differences among Group 1, 2 and 3 were all significant (P<.05). CONCLUSION: The shear bond strength of the gingiva-colored composite was not less than that of the tooth-colored composite. Thus, repairing or fabricating ceramic restorations using the gingiva-colored composite resin can be regarded as a practical method. Especially, the prognosis would be fine when applied on porcelain surfaces.