Effect of sintering cycle on the strength and translucency of multilayered zirconia.

PURPOSE: A newly introduced sintering protocol promises to offer higher translucency while not significantly compromising the flexural strength of the material. However, the effect of the novel sintering protocol has not been thoroughly validated. The purpose of this study was to measure and compare the effect of two sintering protocols on the translucency and flexural strength of two multilayered zirconia materials. MATERIALS AND METHODS: Two types of multilayered zirconia materials (ZirCAD Prime and Prime esthetic) were selected. Presintered disk specimens were obtained from Translucent, Gradient, and Dentin layers (n = 20). The disks were allocated to 2 groups: standard sintering protocol (peak temperature 1500°C) and high translucency sintering protocol (peak temperature 1600°C). After the sintering process, 10 specimens from each group were randomly selected. The optical values (L*, a*, b*) were measured and used to assess translucency using the relative translucency parameter (RTP00) and translucency differences (ΔRTP00). Then, all 20 specimens were tested for biaxial flexural strength. The outcomes were analyzed. The analysis of variance is used to analyze any significant effects on translucency and flexural strength. Then, any significant difference in the translucency and flexural strength between all pairs of materials was analyzed using Bonferroni-corrected Student's t-test (α = 0.05). RESULTS: The high translucency sintering protocol significantly decreased biaxial strength in the Prime translucent and dentine layer, Prime esthetic translucent, and gradient layer. RTP00 was significantly reduced in the Prime gradient and Prime esthetic gradient layer when sintered with a high translucency protocol. The lowest ΔRTP00 was observed in the Prime dentine layer, while the highest ΔRTP00 was observed in the Prime esthetic dentin layer. CONCLUSIONS: High translucency protocol significantly lowers the biaxial flexural strength of both multilayered materials, but the alteration in translucency is within clinically acceptable thresholds (TAT00 = 2.62).

The effect of crowding on the accuracy of 3-dimensional printing.

INTRODUCTION: The purpose of this study was to evaluate the accuracy of 3-dimensional (3D) printed aligners compared to conventional vacuum-formed thermoplastic aligners with varying levels of dental crowding. METHODS: Digital intraoral scans of 10 cases were assigned to their respective groups (n = 10, each, 30 total) as follows: no crowding (control), moderate crowding, and severe crowding. Digital images of these models were created in standard tessellation language (STL) file format using 3Shape software and randomly 3D printed. The STL files of each case were also sent to a dental laboratory to fabricate vacuum-formed samples, the current technology used for manufacturing aligners. The intaglio surfaces of fabricated aligners in both groups were scanned using cone beam computed tomography to create STL files, which were then compared to the original STL files of the cases using Geomagic Control X software. Absolute deviations from the original file and root mean square values were recorded. A Kruskal-Wallis test was conducted to analyze the difference in average deviation, and a t-test was repeated for the RMS measure. The significance level was set at 0.05. RESULTS: The crowding did not affect the trueness of aligners manufactured using 3D printing or conventional vacuum-forming techniques (P = 0.79). 3D-printed aligners showed less deviation than the vacuum-formed samples (0.1125 mm vs 0.1312 mm; P <0.01). Aligners manufactured with the vacuum-forming technique had significantly higher variation than those with the 3D printing process (P = 0.04). CONCLUSIONS: 3D aligners printed directly from an STL file exhibited better precision and trueness than those fabricated using the conventional vacuum-forming technique. Since accuracy is defined as a combination of precision and trueness, it is concluded that direct printing from an STL file can be used to manufacture aligners.

Influence of the Residual Ridge Widths and Implant Thread Designs on Implant Positioning Using Static Implant Guided Surgery.

PURPOSE: Aggressive implant macrothread designs have been widely used. However, the effects of the aggressive thread design on the accuracy of static guided surgery, especially in a case of narrow residual ridge, have not been well-studied. The aim of this study was to evaluate the effects of two different implant macrothread designs and the residual ridge widths on the accuracy of tooth-supported static guided implant surgery. MATERIALS AND METHODS: Forty implant fixtures with two different macrodesigns: a conventional thread design bone level tapered (BLT), and an aggressive thread design bone level tapered (BLX) were placed in 40 simulated polyurethane models with narrow and wide residual ridges. The placed implant positions were compared with the planned implant position and angulational deviation, as well as three-dimensional (3D) deviations at the entry and apex of the implant were measured. One-way ANOVA with Tukey's multiple comparisons (ɑ = 0.05) were used to determine level of significance between the mean and variance deviation values. 95% confidence intervals and box plots were used to demonstrate the means and ranges of precision. RESULTS: In terms of angulational deviation, there was no statistically significant difference in the mean deviations for both types of implants, p = 1.55 and p = 0.84 for wide and narrow ridge groups, respectively. However, the range of deviation was much larger in the narrow ridge of the BLX group compared to the BLT group. In both narrow ridge and wide ridge, the BLX group had lower mean 3D deviation values at both the entry and the apex with statistically significant differences for both entry point of the wide ridge (p = 0.027) and narrow ridge (p = 0.022) as well as at the apex of the wide ridge (p = 0.006) but not the apex of the narrow ridge (p = 0.142). CONCLUSION: The aggressive larger thread design of dental implants may influence the accuracy of implant placement more than the ridge dimension.

Influence of Metal Guide Sleeves on the Accuracy and Precision of Dental Implant Placement Using Guided Implant Surgery: An In Vitro Study.

PURPOSE: Metal sleeves are commonly used in implant guides for guided surgery. Cost and sleeve specification limit the applications. This in vitro study examined the differences in the implant position deviations produced by a digitally designed surgical guide with no metal sleeve in comparison to a conventional one with a metal sleeve. MATERIALS AND METHODS: The experiment was conducted in two steps for each step: n = 20 casts total, 10 casts each group; Step 1 to examine one guide from each group with ten implant placements in a dental cast, and Step 2 to examine one guide to one cast. Implant placement was performed using a guided surgical protocol. Postoperative cone-beam computed tomography images were made and were superimposed onto the treatment-planning images. The implant horizontal and angulation deviations from the planned position were measured and analyzed using t-test and F-test (p = 0.05). RESULTS: For Step 1 and 2, respectively, implant deviations for the surgical guide with sleeve were -0.3 ±0.17 mm and 0.15 ±0.23 mm mesially, 0.60 ±1.69 mm, and -1.50 ±0.99 mm buccolingual at the apex, 0.20 ±0.47 mm and -0.60 ±0.27 mm buccolingual at the cervical, and 2.73° ±4.80° and -1.49° ±2.91° in the buccolingual angulation. For Step 1 and 2, respectively, the implant deviations for the surgical guide without sleeve were -0.17 ±0.14 mm and -0.06 ±0.07 mm mesially, 0.35 ±1.04 mm and -1.619 ±1.03 mm buccolingual at the apex, 0.10 ±0.27 mm and -0.62 ±0.27 mm buccolingual at the cervical, and 1.73° ±3.66° and -1.64° ±2.26° in the buccolingual angulation. No statistically significant differences were found in any group except for mesial deviation of the Step 2 group (F-test, p < 0.001). CONCLUSIONS: A digitally designed surgical guide with no metal sleeve demonstrates similar accuracy but higher precision compared to a surgical guide with a metal sleeve. Metal sleeves may not be required for guided surgery.

Influence of implant diameter on accuracy of static implant guided surgery: An in vitro study.

STATEMENT OF PROBLEM: Static guided implant surgery may be the most accurate method of implant placement to date. However, within the same guided implant system, whether accuracy is affected when placing a larger diameter implant that requires more drills than a smaller diameter implant is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the influence of implant diameter on the angulation and 3-dimensional (3D) deviations of posterior single implant placement using static guided surgery. MATERIAL AND METHODS: A polyurethane dental cast was made with an edentulous site at the maxillary right first molar position. Identical implant planning for each of 3 dental implant diameters 3.3, 4.1, and 4.8 mm (Straumann BLT) were made, and surgical guides for each implant diameters were fabricated by stereolithography. Fifteen implants of each diameter (N=45) were placed in simulated casts. A scan body was placed and the cast was scanned using an intraoral scanner. The positional discrepancies of implant placement, including angulation as well as 3D implant cervical and apex area deviations, were compared with the planned position. Linear ANOVA single factor analysis (ɑ=.05) was used, and box plots were made. RESULTS: The ranges of angulation deviations for 3.3-, 4.1-, and 4.8-mm implants were 3.6 degrees to 6.0 degrees, 3.7 degrees to 7.7 degrees, and 3.1 degrees to 6.7 degrees, respectively. The ranges of 3D implant entry deviations of 3.3-, 4.1-, and 4.8-mm implants were 0.96 to 1.4, 0.85 to 1.72, and 0.89 to 1.78 mm, respectively. The ranges of 3D implant apex of 3.3-, 4.1-, and 4.8-mm implants were 0.63 to 1.21, 0.64 to 1.48, and 0.48 to 1.27 mm, respectively. No statistically significant differences were found in any of the 3 measurements: P=.67 for deviation in angulation; P=.27 for 3D implant deviation of entry; and P=.3 for 3D implant deviation of the apex. CONCLUSIONS: Implant diameters had no significant effect on placement deviations when a single posterior static guided surgery was used.

Effect of print angulation on the accuracy and precision of 3D-printed orthodontic retainers.

INTRODUCTION: The study aimed to (1) compare the accuracy and precision of 3-dimensional (3D) printed retainers at various angulations and (2) evaluate the effect of angulation on printing time and the amount of resin consumed. METHODS: Using a stereolithography 3D printer, 60 clear retainers were printed at 5 angulations (n = 12, each): 15°, 30°, 45°, 60°, and 90°. Samples for each group were randomly printed in a batch of 6 retainers at all print angulations as print 1 and print 2 cycles. Digital images of the original and printed samples were superimposed. Discrepancies on 8 landmarks were measured by 2 independent examiners, and 0.25 mm was set as the clinically acceptable threshold to determine the accuracy of the retainers. RESULTS: Deviations ranged from 0.074 mm to 0.225 mm from the reference retainer at the cusp tips and incisal edges at all angulations, falling within the threshold of clinical acceptance. However, smooth surface measurements with deviations up to 0.480 mm were deemed clinically not acceptable. Three-dimensional printing at 15° was estimated to be the most time-efficient, whereas 3D printing at 45° was shown to be the most cost-effective setting. CONCLUSIONS: Three-dimensional printed retainers, using a stereolithography printer, were found to be accurate within 0.25 mm at all print angulations at the cusp tips and incisal edges compared with the digital reference file. Smooth facial surfaces did not meet clinical acceptability. Print angulations were shown to affect the cost and amount of resin used.

Comparison of 3-dimensional printing technologies on the precision, trueness, and accuracy of printed retainers.

INTRODUCTION: This study aimed to evaluate the differences in the precision, trueness, and accuracy of 3-dimensional (3D) printed clear orthodontic retainers fabricated using printer systems with different printing technologies. METHODS: Retainers (n = 15) were 3D printed using 4 different printers: stereolithography (SLA), digital light processing (DLP), continuous DLP, and polyjet photopolymer (PPP) printers. Printed retainers were transformed into a digital image through a cone-beam computed tomography scan and compared with the original image using 3D superimposition analysis software. At previously chosen landmarks (R6, L6, R3, L3, R1, and L1), intaglio surfaces of the retainers were compared to that of the reference model. The intercanine and the intermolar width measurements were also assessed. A discrepancy of up to 0.25 mm between the printed retainer and the reference retainer intaglio surfaces indicated accuracy and clinical acceptability. Precision and trueness were also determined. Root mean square and percent of points within the tolerance level were calculated for precision and trueness for each retainer. Statistical significance was set at P <0.05. RESULTS: Interrater correlation coefficient indicated good agreement. Statistically significant differences were found between printer types among the 6 landmarks and the arch width measurements. When evaluating tolerance level and root mean square, statistically significant differences in median precision and trueness among each printer type were found. CONCLUSION: Retainers fabricated by SLA, DLP, continuous DLP, and PPP technologies were shown to be clinically acceptable and accurate compared to the standard reference file. Based on both high precision and trueness, SLA and PPP printers yielded the most accurate retainers.

Implant Site Preparation Application of Injectable Platelet-Rich Fibrin for Vertical and Horizontal Bone Regeneration: A Clinical Report.

Guided bone regeneration (GBR) using a combined injectable platelet-rich fibrin (i-PRF), leukocyte- and platelet-rich fibrin (L-PRF), and biocompatible bone substitute material, is a convenient and effective method to augment a combined vertical and horizontal bone defect. This approach can create sufficient bone quality and quantity for implant surgical sites. A 55-year-old Asian woman presented with a severe bone defect in posterior mandible. The edentulous mandibular alveolar ridge was severely resorbed vertically and horizontally. A GBR procedure using i-PRF and L-PRF combined with particulate bone graft was performed. Postoperative cone beam computed tomography scans, 8 months after the augmentation, revealed a large regeneration of the alveolar bone sufficient for implant placement. A combination i-PRF/L-PRF and particulate bone graft may provide biologically active molecules and a scaffold for osteogenesis. This treatment protocol may be a viable option for a large bone defect required augmentation before implant placement.

Erbium laser-assisted ceramic debonding: a scoping review.

PURPOSE: Removal of ceramic restorations and appliances can be time consuming, invasive, and inconvenient. Erbium lasers offer an alternative noninvasive method for debonding of ceramic appliances. This paper aims to provide a comprehensive review of current literature on the effectiveness of erbium lasers for removal of ceramic restorations and appliances from natural teeth and dental implants. METHODS: A comprehensive search of 7 databases, including Medline (Ovid), Embase, Dentistry and Oral Sciences Source (DOSS), Web of Science, Cochrane Library, and ProQuest Dissertations and Theses was performed. The inclusion and exclusion criteria were agreed prior to the literature search. Two reviewers independently screened the title and abstract. A third reviewer then broke the tie, if any. The selected articles then underwent full text review and the data was extracted. RESULTS: The search identified 4117 unique articles published through June 10, 2021. Studies were assessed and categorized based on the type of restoration/appliance, type of abutment, type of laser, laser settings, efficacy of debonding, and pulpal temperature rise. Thirty-eight full-text articles were reviewed for inclusion. Time for ceramic debonding varies depending on the type of restorations and materials. Removal of zirconia crowns from teeth and implant abutments requires a longer period of time compared to lithium disilicate crowns. Temperature increases were reported as 5.5 degrees or less. Laser setting and laser type affect the debonding time and the increase in temperature. Examinations of debonded ceramics demonstrated no known structural damages resulting from laser applications. CONCLUSIONS: Erbium lasers are effective noninvasive tools to remove all ceramic restorations/appliances from natural teeth and implant abutments without causing harm to abutments. Laser-assisted debonding should be considered as a viable alternative to rotary instrumentation for ceramic crowns; however, clinical studies of erbium-assisted ceramic retrieval are needed.

Creating a digital duplicate denture file using a desktop scanner and an open-source software program: A dental technique.

This article describes a digital technique for obtaining a standard tessellation language (STL) file of a complete denture using a desktop scanner and an open-source software program. Accurate recording of the surface details of the denture in 3D was performed using a desktop scanner. The generated STL file from this technique represents a digital duplicate of the scanned denture. This file can be used for surgical implant placement planning, fabricating a duplicate denture, and storing the scanned denture as a digital file for future use.

Effectiveness of CAD/CAM technology: A self-assessment tool for preclinical waxing exercise.

INTRODUCTION: This study assessed the utility of CAD/CAM technology as a self-assessment tool for preclinical waxing compared to traditional student self-assessment to evaluate preclinical work. MATERIAL AND METHODS: Thirty-seven students completed the wax-up of the maxillary left central incisor with the goal of recreating original anatomy and completed a traditional self-assessment. The original, unreduced cast and waxings were scanned with an intraoral scanner (E4D, Planmeca). Using CAD/CAM software (Compare, Planmeca), each waxing was superimposed over the original. Tolerance (250 µm) was set to illustrate under- and over-contoured areas, enabling visualisation of the waxing compared to original in three dimensions. Students then completed another self-assessment and an exit survey. RESULTS: Twenty-four per cent of self-assessment responses changed after using Compare Software. 20% changed from satisfactory to unsatisfactory. Four per cent changed from unsatisfactory to satisfactory. Greatest change in response occurred in the Incisal Edge (49%) rubric category. Interproximal Contact Area (3%) demonstrated least change in response. Seventy per cent strongly agreed that Compare Software enabled more effective assessment of Lingual Contour. Eight per cent strongly disagreed that Compare Software enabled more effective assessment of finishing. DISCUSSION: CAD/CAM software can improve student's critical self-assessment. Different rubric categories demonstrated differing rates of response change, indicating more critical of certain aspects of the waxing. Majority strongly agreed that the software enabled more effective self-assessment. CONCLUSION: CAD/CAM technology enhances student's learning in dental wax-up through improving self-assessment. This technology may improve teacher-student communication, reduce one-on-one teaching time and allow higher student-teacher ratio.

Effects of two Postprocessing Methods onto Surface Dimension of in-Office Fabricated Stereolithographic Implant Surgical Guides.

PURPOSE: To evaluate the effects of two postprocessing methods in terms of the overall, intaglio, and cameo surface dimensions of in-office stereolithographic fabricated implant surgical guides. MATERIALS AND METHODS: Twenty identical implant surgical guides were fabricated using a stereolithographic printer. Ten guides were postprocessed using an automated method. The other ten guides were postprocessed using a series of hand washing in combination with ultrasonics. Each guide was then scanned using cone-beam computed tomography to produce a set of digital imaging and communications in medicine (DICOM) files which were converted into standard tessellation language (STL) files. The STL file was then superimposed onto the original STL design file using the best fit alignment. The average positive and negative surface discrepancy differences in terms of means and variances were analyzed using t-test (α = 0.05). RESULTS: For the alternative group, the average positive and negative overall, intaglio, and cameo surface discrepancies were 77.38 ± 10.68 µm and -67.74 ± 6.55 µm; 78.83 ± 8.65 µm and -68.16 ± 5.26 µm; and 70.5 ± 8.48 µm -64.84 ± 5.55 µm, respectively. For the automated group, the average positive and negative overall, intaglio, and cameo surface discrepancies were 51.88 ± 4.38 µm and -170.7 ± 11.49 µm; 64.3 ± 4.44 µm and -89.45 ± 6.25 µm; and 83.59 ± 4.81 µm and -144.26 ± 13.19 µm, respectively. There was a statistical difference between the means of the two methods for the overall, intaglio, and cameo positive and negative discrepancies (p < 0.001). CONCLUSIONS: For a single implant tooth-supported implant guide, using hand washing with ultrasonics appeared to be consistently better than the automated method. The manual method presented with more positive discrepancies, while the automated method presented with more negative discrepancies.

Monolithic Zirconia Partial Coverage Restorations: An In Vitro Mastication Simulation Study.

PURPOSE: To evaluate the survival rate (fatigue resistance), bonding efficiency and marginal integrity of monolithic zirconia partial and full coverage single restorations adhesively bonded to the tooth structure using air-particle abrasion, a primer with 10-methacryloyloxydecyl dihydrogen phosphate and a composite-resin cement (APC) protocol. MATERIALS AND METHODS: Extracted human premolars (N = 32) were randomly divided into four groups of eight specimens each. Premolars were prepared for the following restorations: full crown (group 1, control), mesial-occlusal-distal-facial onlay (MODF, group 2) preserving 2 mm facio-lingual functional cusp width, mesial-occlusal-distal-lingual onlay (MODL, group 3) preserving 2 mm facio-lingual nonfunctional cusp width, mesial-occlusal-distal-buccal-lingual onlay (MODBL, group 4), overlay preparation. All restorations were milled from monolithic 3 mol% yttria (3Y) zirconia blocks (ZirCad, A1 LT, Ivoclar Vivadent) with CAD/CAM software presets at minimum occlusal and axial thicknesses of 1 mm. The intaglio surface of the restorations was air-particle abraded (50 µm Al2 O3 , 2-Bar pressure, 15 s, 10 mm distance) and primed. An adhesive cement system was used to bond the restorations. Each group was subjected to thermomechanical loading for 1.2 million cycles (force = 70 N, 1.4 Hz) with simultaneous thermocycling (5-55°C, 30 s dwell time) using a mastication simulator. All specimens were examined under scanning electron microscope (SEM) analysis (30, 100, and 150×) to evaluate cracks and marginal defects. Fracture of restoration and/or fracture within tooth structure, and debonding were considered modes of failure. RESULTS: One specimen from group 2 debonded at 632,000 cycles. None of the specimens failed due to fracture. SEM analysis at 30× indicated marginal integrity issue of the remaining seven intact specimens of group 2 in the area of antagonist contact. No specimens from group 1, 3, and 4 demonstrated marginal integrity issue at 30×. None of the specimens demonstrated any microcrack at 100× and150×. CONCLUSIONS: Due to its fatigue resistance, 3Y-zirconia is a viable option for partial and full coverage single restorations. Following a strict bonding protocol, zirconia demonstrated durable adhesion to the tooth structure. Occlusal contact on restoration margins should be avoided.

Accuracy and precision of 3D-printed implant surgical guides with different implant systems: An in vitro study.

STATEMENT OF PROBLEM: Implant guided surgery systems promise implant placement accuracy and precision beyond straightforward nonguided surgery. Recently introduced in-office stereolithography systems allow clinicians to produce implant surgical guides themselves. However, different implant designs and osteotomy preparation protocols may produce accuracy and precision differences among the different implant systems. PURPOSE: The purpose of this in vitro study was to measure the accuracy and precision of 3 implant systems, Tapered Internal implant system (BioHorizons) (BH), NobelReplace Conical (Nobel Biocare) (NB), and Tapered Screw-Vent (Zimmer Biomet) (ZB) when in-office fabricated surgical guides were used. MATERIAL AND METHODS: A cone beam computed tomography (CBCT) data set of an unidentified patient missing a maxillary right central incisor and intraoral scans of the same patient were used as a model. A software program (3Shape Implant Studio) was used to plan the implant treatment with the 3 implant systems. Three implant surgical guides were fabricated by using a 3D printer (Form 2), and 30 casts were printed. A total of 10 implants for each system were placed in the dental casts by using the manufacturer's recommended guided surgery protocols. After implant placement, postoperative CBCT images were made. The CBCT cast and implant images were superimposed onto the treatment-planning image. The implant positions, mesiodistal, labiopalatal, and vertical, as well as implant angulations were measured in the labiolingual and mesiodistal planes. The displacements from the planning in each dimension were recorded. ANOVA with the Tukey adjusted post hoc pairwise comparisons were used to examine the accuracy and precision of the 3 implant systems (α=.05). RESULTS: The overall implant displacements were -0.02 ±0.13 mm mesially (M), 0.07 ±0.14 mm distally (D), 0.43 ±0.57 mm labially (L), and 1.26 ±0.80 mm palatally (P); 1.20 ±3.01 mm vertically in the mesiodistal dimension (VMD); 0.69 ±2.03 mm vertically in the labiopalatal dimension (VLP); 1.69 ±1.02 degrees in mesiodistal angulation (AMD); and 1.56 ±0.92 degrees in labiopalatal angulation (ALP). Statistically significant differences (ANOVA) were found in M (P=.026), P (P=.001), VMD (P=.009), AMD (P=.001), and ALP (P=.001). ZB showed the most displacements in the M and vertical dimensions and the least displacements in the P angulation (P<.05), suggesting statistically significant differences among the M, VMD, VLP, AMD, and ALP. NB had the most M variation. ZB had the least P deviation. NB had the fewest vertical dimension variations but the most angulation variations. CONCLUSIONS: Dimensional and angulation displacements of guided implant systems by in-office 3D-printed fabrication were within clinically acceptable limits: <0.1 mm in M-D, 0.5 to 1 mm in L-P, and 1 to 2 degrees in angulation. However, the vertical displacement can be as much as 2 to 3 mm. Different implant guided surgery systems have strengths and weaknesses as revealed in the dimensional and angulation implant displacements.

Fracture Load of Different Zirconia Types: A Mastication Simulation Study.

PURPOSE: To assess the effect of yttria mol% concentration and material thickness on the biaxial fracture load (N) of zirconia with and without mastication simulation. MATERIALS AND METHODS: Disk-shaped specimens (N = 120) of 3 mol% yttria-partially stabilized zirconia, 3Y-PSZ (Katana High Translucent, Kuraray Noritake), 4 mol% yttria-partially stabilized zirconia, 4Y-PSZ (Katana Super Translucent Multi Layered) and 5 mol% Yttria-partially stabilized zirconia, 5Y-PSZ (Katana Ultra Translucent Multi Layered) were prepared to thicknesses of 0.7 and 1.2 mm. For each thickness, the biaxial fracture load (N) was measured with and without mastication simulation with 1.2 million cycles at a 110-N load and simultaneous thermal cycling at 5°C to 55°C. The data were analyzed by three-way Analysis of Variance (α = 0.05) and Tukey-Kramer adjusted multiple comparison test. RESULTS: Yttria mol% concentration and material thickness had a statistically significant effect on the mean biaxial fracture load (F = 388.16, p < 0.001 and F = 714.33, p < 0.001 respectively). The mean biaxial fracture load ranged from the highest to the lowest; 3Y-PSZ, 4Y-PSZ, and 5Y-PSZ (p = 0.012). The mean biaxial fracture load of the 1.2 mm thickness groups was significantly higher than 0.7 mm thickness at any given condition (p = 0.002). Not all specimens survived the mastication simulation protocol. Fifty percent of the 0.7-mm-thick 4Y-PSZ specimens, 70% of the 0.7-mm-thick 5Y-PSZ specimens and 20% of 1.2-mm-thick 5Y-PSZ specimens fractured during mastication simulation. Mastication simulation had no statistically significant effect on the biaxial fracture load (F = 1.24, p = 0.239) of the survived specimens. CONCLUSIONS: Lowering yttria mol% concentration and increasing material thickness significantly increases the fracture load of zirconia. At 0.7 mm thickness, only 3Y-PSZ survived masticatory simulation. A minimum material thickness of 1.2 mm is required for 4Y-PSZ or 5Y-PSZ.

Accuracy of Implant Placement Position Using Nondental Open-Source Software: An In Vitro Study.

PURPOSE: To evaluate the accuracy of implant placement position using two different dental implant planning software. MATERIALS AND METHODS: A set of Digital Imaging and Communications in Medicine (DICOM) files from a cone beam computed tomography of a patient missing maxillary right first premolar was used. Implant planning was done using two open-source programs: A nondental 3D Slicer/Blender (3DSB) software and a commercial dental implant treatment planning program: Blue Sky Plan 4 (BSP4). An intraoral scan of the same patient was used to create a standard tessellation language (STL) file of the maxillary arch and later printed into 20 identical casts. Ten surgical guides were printed for each group as well. A dental implant (3.8 mm × 12 mm, Biohorizons) was placed into each cast using fully guided surgical protocol. The horizontal displacements at the implant cervical platform and at the implant apex as well as the angulation displacements were measured using digital scanning of the implant scan bodies and were analyzed using a 3D compare software. Statistical analyses were conducted (⍺ = 0.05) using t-test and F-test to examine differences in trueness and precision, respectively. RESULTS: The average horizontal deviations for the platform and the apex, respectively, were 0.33 ± 0.12 mm and 0.76 ± 0.30 mm for 3DSB and 0.44 ± 0.21 mm and 0.98 ± 0.48 mm for BSP4. The average angulation deviations for 3DSB and BSB4 were 2.34 ± 0.93° and 3.07 ± 1.57°, respectively. There were no statistical differences in the means (t-test) of the platform, apex, and angulation deviations (p = 0.16, p = 0.19, and p = 0.18, respectively). There were statistical differences in the variances (F test) of the platform (p = 0.043) and angulation (p = 0.049) deviations but not the apex (p = 0.059) deviations. CONCLUSIONS: The combination of nondental open-source software, 3D Slicer/Blender can be used to plan implant guided surgery with an accuracy similar to commercial dental software with slightly higher precision. Open-source nondental software can be considered as an alternative in dental implant treatment planning and guided surgery.

Intaglio Surface Dimension and Guide Tube Deviations of Implant Surgical Guides Influenced by Printing Layer Thickness and Angulation Setting.

PURPOSE: To measure overall intaglio dimensional and tube deviations of implant guides printed at 50 and 100 µm layer thickness at 0°, 45°, and 90° angulation using a stereolithographic (SLA) printer. MATERIALS AND METHODS: A surgical implant guide design from a subject missing a maxillary right central incisor, used as the original standard tessellation language (STL) were stereolithographically fabricated at each thickness and angulation, 50 and 100 µm layer thickness at 0°, 45°, and 90° angulation (n = 10 each group). The guide was then scanned using cone beam computed tomography. The digital imaging and communications in medicine (DICOM) scanned files were then converted to an STL format. The overall dimensional deviations of the intaglio surface and the positioning of the implant guide tube were then superimposed onto the original designed STL file using best-fitting alignment. A t-test and an F-test as well as ANOVA followed by a post hoc t-test were used to determine statistical significant differences (α = 0.05) for the intaglio surface and guide tube deviation, respectively. RESULTS: The overall intaglio surface discrepancies (µm) printed at 0°, 45°, and 90° were 55.07 ± 1.36, 52.39 ± 2.09, and 61.02 ± 15.96 for 50 µm layer; and 98.38 ± 10.55, 84.47 ± 10.61, and 90.26 ± 5 for 100 µm layer with statistically significant differences for both t-test and F-test, p < 0.001. The maximal guide tube linear deviations (µm) printed at 0°, 45°, and 90° were 10.78 ± 3.84, 8.16 ± 3.68, and 12.57 ± 5.39 for 50 µm layer (ANOVA, p = 0.096); and 10.95 ± 5.23, 16.79 ± 4.97, and 22.63 ± 2.81 for 100 µm layer (ANOVA, p < 0.001). The maximal guide tube angular deviations (°) printed at 0°, 45°, and 90° were 1.29 ± 0.30, 0.64 ± 0.13, and 0.56 ± 0.21 for 50 µm layer (ANOVA, p < 0.001); and 1.57 ± 0.29, 0.86 ± 0.14, and 1.02 ± 0.31 for 100 µm layer (ANOVA, p = 0.034). There was a statistical difference in the deviations between 50 and 100 µm layer printing in all printed angulations except at 0° (t-test, p = 0.05, p = 0.03, and p = 0.001 for 0°, 45°, and 90°) and linear deviations (t-test, p < 0.001, p = 0.009, and p = 0.001 for 0°, 45°, and 90°). CONCLUSION: Printing at 50 µm layer reduces dimensional intaglio deviations in general and reduces tube angular deviations with different angulations of printing. However, the deviations were only ∼60 to 100 µm for the intaglio dimension deviations; and ∼0.04 to 0.26 mm and ∼0.25° to ∼2° for tube deviations.

Salivary protein biomarkers associated with orthodontic tooth movement: A systematic review.

OBJECTIVE: Saliva can provide a non-invasive approach to indicate changes in the oral and systemic conditions. Salivary proteomics allows the discovery of new protein biomarkers associated with certain conditions. The effectiveness and physiological effects of orthodontic tooth movement in theory can be measured using salivary protein biomarkers. SETTING AND SAMPLE POPULATION: This study applied a systematic review to analyse current literature to define and summarize salivary biomarkers associated with orthodontic tooth movement identified by mass spectrometry proteomics and other protein detection techniques. MATERIALS AND METHODS: Peer-reviewed articles published through the 15th of November 2018 via the PubMed, EMBASE, Web of Science and Dentistry & Oral Sciences databases were reviewed. Only studies analysing protein biomarkers in saliva samples collected from human subjects associated with orthodontic treatments were included. RESULTS: Out of 482 articles, 7 studies were selected. Sample size ranged from 3 to 72 subjects. Minor variations of unstimulated whole saliva sample collection protocol were noted. Mass spectrometry proteomics and ELISA represented the majority of biomarker discovery and targeting, respectively. Twenty biomarkers were identified or chosen as target biomarkers. CONCLUSION: Salivary proteins may be used to indicate effectiveness of orthodontic treatment and orthognathic treatment as well as adverse treatment consequence, such as root resorption.

Influence of Fractionation Methods on Physical and Biological Properties of Injectable Platelet-Rich Fibrin: An Exploratory Study.

Injectable platelet-rich fibrin (i-PRF) has been used as an autografting material to enhance bone regeneration through intrinsic growth factors. However, fractionation protocols used to prepare i-PRF can be varied and the effects of different fractionation protocols are not known. In this study, we investigated the influence of different fractions of i-PRF on the physical and biological properties derived from variations in i-PRF fractionation preparation. The i-PRF samples, obtained from the blood samples of 10 donors, were used to harvest i-PRF and were fractioned into two types. The yellow i-PRF fractionation was harvested from the upper yellow zone, while the red i-PRF fractionation was collected from both the yellow and red zone of the buffy coat. The viscoelastic property measurements, including the clot formation time, α-angle, and maximum clot firmness, were performed by rotational thromboelastometry. The fibrin network was examined using a scanning electron microscope. Furthermore, the concentration of growth factors released, including VEGF, TGF-ß1, and PDGF, were quantified using ELISA. A paired t-test with a 95% confidence interval was used. All three viscoelastic properties were statistically significantly higher in the yellow i-PRF compared to the red i-PRF. The scanning electron microscope reviewed more cellular components in the red i-PRF compared to the yellow i-PRF. In addition, the fibrin network of the yellow i-PRF showed a higher density than that in the red i-PRF. There was no statistically significant difference between the concentration of VEGF and TGF-ß1. However, at Day 7 and Day 14 PDGF concentrations were statistically significantly higher in the red i-PRF compared to the yellow group. In conclusion, these results showed that the red i-PRF provided better biological properties through the release of growth factors. On the other hand, the yellow i-PRF had greater viscoelastic physical properties. Further investigations into the appropriate i-PRF fractionation for certain surgical procedures are therefore necessary to clarify the suitability for each fraction for different types of regenerative therapy.

Trephination-based, guided surgical implant placement: A clinical study.

STATEMENT OF PROBLEM: Conventional guided implant surgery promises clinical success through implant placement accuracy; however, it requires multiple drills along with surgical sleeves and sleeve adapters for the horizontal and vertical control of osteotomy drills. This results in cumbersome surgery, problems with patients having limited mouth opening, and restriction to specific drill or implant manufacturers. A protocol for using trephination drills to simplify guided surgery and accommodate multiple implant systems is introduced. PURPOSE: The purpose of this clinical study was to evaluate the accuracy of implant placement using this novel guided trephine drill protocol with and without a surgical sleeve. MATERIAL AND METHODS: Intraoral scanning and preoperative cone beam computed tomography (CBCT) scans were used for implant treatment planning. Surgical guides were fabricated using stereolithography. Implant surgery was performed using the guided trephination protocol with and without a surgical sleeve. Postoperative CBCT scans were used to measure the implant placement deviations rather than the implant planning position. Surgical placement time and patient satisfaction were also documented. One-tailed t test and F-test (P=.01) were used to determine statistical significance. RESULTS: Thirty-five implants in 17 participants were included in this study. With a surgical sleeve, implant positional deviations were 0.51 ±0.13 mm vertically, 0.32 ±0.10 mm facially, 0.11 ±0.11 mm lingually, and 0.38 ±0.13 mm mesially. Without a surgical sleeve, implant positional deviations were 0.58 ±0.27 mm vertically, 0.3 ±0.14 mm facially, 0.39 ±0.16 mm lingually, and 0.41 ±0.12 mm mesially. No statistically significant difference was found between the 2 protocols (P>.01), except that the sleeve group had greater vertical control precision (F-test, P=.006), reduced placement time, and the time variation was reduced (t test, P=.003; F-test, P<.001). CONCLUSIONS: This trephination-based, guided implant surgery protocol produces accurate surgical guides that permit guided surgery in limited vertical access and with the same guided surgery protocol for multiple implant systems. Guided sleeves, although not always necessary, improve depth control and reduce surgical time in implant placement.