Zirconia full-arch implant prostheses: Survival, complications, and prosthetic space dimensions with 115 edentulous jaws.

PURPOSE: To assess the survival and complication rates of 115 monolithic zirconia implant-supported fixed complete dental prostheses (IFCDPs) with an up to 6-year follow-up. MATERIALS AND METHODS: One hundred fifteen edentulous jaws (71 patients) underwent complete-arch implant treatment with a digital workflow and were rehabilitated with monolithic zirconia IFCDPs. The primary outcome was to assess survival and complication rates while the secondary outcome was to measure the cross-sectional dimensions (prosthetic space) of those 115 monolithic zirconia IFCDPs and to correlate potential technical complications with the prosthetic space dimensions. RESULTS: Out of the 115 zirconia IFCDPs, 2 fractured, yielding a 98.6% survival rate up to a 6-year follow-up. The most commom minor technical complications were loss of screw access channel filling and porcelain chipping for the modified monolithic IFCDPs. There was no significant association between the count and type of complications and jaw location (maxilla vs. mandible) or prosthesis type (FP1 vs. FP3), according to Fisher's exact test. For maxillary zirconia IFCDPs, the mean square surface for the at the posterior abutment cross-sectional area was 25.18 mm2 at the lingual side of the abutment and 34.19 mm2 at the buccal side, respectively. The anterior abutment cross-sectional area was 33.92 mm2 at the lingual side of the abutment and 29.49 mm2 at the buccal side, respectively. For mandibular zirconia IFCDPs, the mean square surface at the posterior abutment cross-sectional area was 29.89 mm2 at the lingual side of the abutment and 39.05 mm2 at the buccal side, respectively. The anterior abutment cross-sectional area was 27.07 mm2 at the lingual side of the abutment and 56.50 mm2 at the buccal side, respectively. At the connector cross-sectional area, the mean square surface for the maxillary zirconia IFCDPs was 64.33 and 90.56 mm2 for the mandibular zirconia IFCDPs. The two fractures occurred in the midline (anterior area) for both maxillary FP1 prosthesis and mandibular FP3 prosthesis. The mean surface area at the connector for the maxillary FP1 prosthesis was 28.50 and 82.11 mm2 for the mandibular FP3 prosthesis, and was within the range of IFCDP connector square surface area. There was no significant association between the thickness of the zirconia prosthesis and the encountered prosthesis fractures. CONCLUSIONS: Monolithic zirconia IFCDPs yielded a 98.6% survival rate, after a mean observation period of 62 months with an SE of 3.1. The connector mean surface area in the two fractured IFCDPs was within the square surface range (minimum-maximum) as for the remaining 113 complication-free IFCDPs.

Fracture resistance, marginal and internal adaptation of innovative 3D-printed graded structure crown using a 3D jet printing technology.

PURPOSE: This in vitro study aimed to create a graded structured dental crown using 3D printing technology and investigate the fracture resistance and the adaptation of this new design. MATERIALS AND METHODS: A dental crown with a uniform thickness of 1.5 mm was designed, and the exported stereolithography file (STL) was used to manufacture 30 crowns in three groups (n = 10), solid (SC), bilayer (BL), and multilayer (ML) crowns using  3D jet printing technology. Marginal and internal gaps were measured using the silicone replica technique. Crowns were then luted to a resin die using a temporary luting agent and the fracture resistance was measured using a universal testing machine. One-way ANOVA and Tukey post hoc tests were used to compare the fracture resistance and the adaptation of crowns at a significance level of 0.05. RESULTS: Mean marginal and internal gap of the ML group were 80 and 82 mm, respectively; which were significantly (p < 0.05) smaller than BL (203 and 183 mm) and SC (318 and 221 mm) groups. The SC group showed the highest mean load at fracture (2330 N) which was significantly (p < 0.05) higher than the BL (1716 N) and ML (1516 N) groups. CONCLUSION: 3D jet printing technology provides an opportunity to manufacture crowns in a graded structure with various mechanical properties. This study provided an example of graded structured crowns and presented their fracture resistance. SC group had the highest fracture resistance; however, ML had the best marginal and internal adaptation.

Comparison of shear bond strength of orthodontic brackets bonded to human teeth with and without fluorotic enamel: A systematic review and meta-analysis of experimental in vitro studies.

The aim of this systematic review was to compare the shear bond strength (SBS) of orthodontic brackets bonded to human teeth with and without enamel fluorosis (EF) using conventional bonding interventions/techniques. An unrestricted search of indexed databases was performed with the following eligibility criteria: (a) human fluorotic teeth (experimental-group); (b) human teeth without fluorosis (control-group); (c) studies using phosphoric acid (PA) etching without air abrasion (AA), PA etching combined with AA, and application of self-etching primer (SEP) alone as bonding interventions/techniques and (d) measuring SBS in megapascals (MPa). Data screening, selection and extraction were performed by two reviewers. The risk of bias (rob) was assessed using the JBI Critical appraisal tool for Quasi-Experimental Studies. Meta-analyses were performed using a random effects model. The quality of available evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach. Ten in vitro studies were included. Subgroup analyses were performed for each intervention type. The SBS was significantly lower in fluorotic teeth when PA was used without AA (mean difference = 3.26 MPa, confidence interval: [1.00, 5.52]); and there were no significant differences for the PA combined with AA and SEP interventions. All studies had a low rob. The overall level of evidence was at best low. The SBS is lower in teeth with EF when traditional PA is used. No significant differences were found in SBS between teeth with and without EF when PA is used with AA or when SEP is used alone.

The role ovariectomies and/or the administration of artificial female sex hormones play in orthodontic tooth movement: A systematic review.

The objective was to assess how ovariectomy or the administration of artificial female sex hormones affects orthodontic tooth movement (OTM) with fixed appliances. An electronic search of indexed databases was completed without language or time restrictions up to June 2022. The following eligibility criteria were utilized: (i) prospective original controlled clinical studies; (ii) experimental studies on animal models; (iii) subjects undergoing orthodontic therapy with fixed appliances; (iv) clearly defined control groups not undergoing ovariectomy or administration of artificial female sex hormone; and (v) studies with experimental groups receiving the intervention of interest (ovariectomy or artificial female sex hormone administration). Review articles, letters to the editor, case reports, case series, commentaries, cross-sectional studies, retrospective studies, and studies with no well-defined control group were excluded. The quality of the available evidence and the risk of bias within the studies were assessed. All disagreements were resolved via discussion. Seven animal studies were included in the systematic review. Five studies reported that ovariectomy increased the rate of orthodontic tooth movement. Two studies reported that the administration of artificial female sex hormones decreased the rate of orthodontic tooth movement. There is an association between ovariectomies and OTM and between the administration of artificial female sex hormones and OTM. The full extent of the association remains unclear due to the biases that are present and the length of time of orthodontic therapy.

Shear bond strength of porcelain to milled and stereolithography additively manufactured zirconia with and without surface treatment: An in vitro study.

STATEMENT OF PROBLEM: Delamination of veneering ceramic is one of the most common challenges relating to veneered zirconia restorations. Additive manufacturing (AM) is a fast-expanding technology that has gained widespread acceptance in dentistry and is increasingly being used to produce dental restorations. However, information about bonding of porcelain to AM zirconia is lacking. PURPOSE: The purpose of this in vitro study was to investigate the shear bond strength (SBS) of porcelain to milled and additively manufactured zirconia, and the effect of surface treatment on bond strength. MATERIAL AND METHODS: A Ø12×5-mm disk was designed virtually to fabricate all specimens, which were divided into 2 groups according to the manufacturing technique: additively manufactured or milled zirconia. The effect of airborne-particle abrasion and a zirconia liner before porcelain application was investigated in both groups. Veneering porcelain was fired into an alumina ring mold on the zirconia surface. SBS was measured by using a universal testing machine at a crosshead speed of 1 mm/min before and after aging (n=10). SBS data were analyzed with 3-way ANOVA (α=.05) RESULTS: A significant difference was found between milled and AM zirconia. The SBS of porcelain to milled zirconia was significantly higher (1.38 MPa) than to AM zirconia (0.68 MPa) (P<.001). The surface treatment of zirconia had no significant effect on porcelain SBS in either group (P=.254), whereas thermocycling significantly reduced the SBS of porcelain to zirconia in both milled and AM groups (P=.001). CONCLUSIONS: Porcelain bonding to milled zirconia was better than to AM zirconia. Pretreating the zirconia substrate before porcelain application did not improve the porcelain bond.

Surface roughness and shear bond strength to composite resin of additively manufactured interim restorative material with different printing orientations.

STATEMENT OF PROBLEM: Additive manufacturing (AM) is a technology that has been recently introduced into dentistry for fabricating dental devices, including interim restorations. Printing orientation is one of the important and influential factors in AM that affects the accuracy, surface roughness, and mechanical characteristics of printed objects. However, the optimal print orientation for best bond strength to 3D-printed interim restorations remains unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effect of printing orientation on the surface roughness, topography, and shear bond strength of AM interim restorations to composite resin. MATERIAL AND METHODS: Disk-shaped specimens (Ø20×10 mm) were designed by a computer-aided design software program (Geomagic freeform), and a standard tessellation language (STL) file was obtained. The STL file was used for the AM of 60 disks in 3 different printing orientations (0, 45, and 90 degrees) by using E-Dent 400 C&B material. An autopolymerizing interim material (Protemp 4) was used as a control group (CNT), and specimens were fabricated by using the injecting mold technique (n=20). Surface roughness (Sa, Sz parameters) was measured by using a 3D-laser scanning confocal microscope (CLSM) at ×20 magnification. For shear bond testing, the specimens were embedded in polymethylmethacrylate autopolymerized resin (n=20). A flowable composite resin was bonded by using an adhesive system. The specimens were stored in distilled water at 37 °C for 1 day and thermocycled 5000 times. The shear bond strength (SBS) was measured at a crosshead speed of 1 mm/min. The data were analyzed by 1-way ANOVA, followed by the Tukey HSD test (α=.05). RESULTS: The 45-degree angulation printing group reported the highest Sa, followed by the CNT and the 90-degree and 0-degree angulations with significant difference between them (P<.001). The CNT showed the highest Sz, followed by the 45-degree, 90-degree, and 0-degree angulations. The mean ±standard deviation SBS was 28.73 ±5.82 MPa for the 90-degree, 28.21 ±10.69 MPa for the 45-degree, 26.21 ±11.19 MPa for the 0-degree angulations and 25.39 ±4.67 MPa for the CNT. However, no statistically significant difference was found in the SBS among the groups (P=.475). CONCLUSIONS: Printing orientation significantly impacted the surface roughness of 3D-printed resin for interim restorations. However, printing orientation did not significantly affect the bond strength with composite resin.

Marginal and internal discrepancies associated with carbon digital light synthesis additively manufactured interim crowns.

STATEMENT OF PROBLEM: The carbon digital light synthesis (DLS) or continuous liquid interface production (CLIP) technology is an innovative additive manufacturing technology using oxygen-inhibited photopolymerization to create a continuous liquid interface of unpolymerized resin between the growing component and the exposure window. This interface eliminates the need for an incremental layer-by-layer approach, allowing for continuous creation and increased printing speed. However, the internal and marginal discrepancies associated with this new technology remain unclear. PURPOSE: The purpose of this in vitro study was to evaluate the marginal and internal discrepancies by using the silicone replica technique of interim crowns fabricated by 3 different manufacturing technologies: direct light processing (DLP), DLS, and milling. MATERIAL AND METHODS: A mandibular first molar was prepared, and a crown was designed with a computer-aided design (CAD) software program. The standard tessellation language (STL) file was used to create 30 crowns from the DLP, DLS, milling technologies (n=10). The gap discrepancy was determined using the silicone replica approach, with 50 measurements made with a ×70 microscope for each specimen for the marginal and internal gaps. The data were analyzed using 1-way ANOVA, followed by the Tukey HSD post hoc test (α=.05). RESULTS: The DLS group had the least marginal discrepancy compared with the DLP and milling groups (P<.001). The DLP group showed the highest internal discrepancy followed by the DLS and milling groups (P=.038). No significant difference was found between DLS and milling in terms of internal discrepancy (P>.05). CONCLUSIONS: The manufacturing technique had a significant effect on both internal and marginal discrepancies. The DLS technology showed the smallest marginal discrepancies.

Artificial intelligence models for tooth-supported fixed and removable prosthodontics: A systematic review.

STATEMENT OF PROBLEM: Artificial intelligence applications are increasing in prosthodontics. Still, the current development and performance of artificial intelligence in prosthodontic applications has not yet been systematically documented and analyzed. PURPOSE: The purpose of this systematic review was to assess the performance of the artificial intelligence models in prosthodontics for tooth shade selection, automation of restoration design, mapping the tooth preparation finishing line, optimizing the manufacturing casting, predicting facial changes in patients with removable prostheses, and designing removable partial dentures. MATERIAL AND METHODS: An electronic systematic review was performed in MEDLINE/PubMed, EMBASE, Web of Science, Cochrane, and Scopus. A manual search was also conducted. Studies with artificial intelligence models were selected based on 6 criteria: tooth shade selection, automated fabrication of dental restorations, mapping the finishing line of tooth preparations, optimizing the manufacturing casting process, predicting facial changes in patients with removable prostheses, and designing removable partial dentures. Two investigators independently evaluated the quality assessment of the studies by applying the Joanna Briggs Institute Critical Appraisal Checklist for Quasi-Experimental Studies (nonrandomized experimental studies). A third investigator was consulted to resolve lack of consensus. RESULTS: A total of 36 articles were reviewed and classified into 6 groups based on the application of the artificial intelligence model. One article reported on the development of an artificial intelligence model for tooth shade selection, reporting better shade matching than with conventional visual selection; 14 articles reported on the feasibility of automated design of dental restorations using different artificial intelligence models; 1 artificial intelligence model was able to mark the margin line without manual interaction with an average accuracy ranging from 90.6% to 97.4%; 2 investigations developed artificial intelligence algorithms for optimizing the manufacturing casting process, reporting an improvement of the design process, minimizing the porosity on the cast metal, and reducing the overall manufacturing time; 1 study proposed an artificial intelligence model that was able to predict facial changes in patients using removable prostheses; and 17 investigations that developed clinical decision support, expert systems for designing removable partial dentures for clinicians and educational purposes, computer-aided learning with video interactive programs for student learning, and automated removable partial denture design. CONCLUSIONS: Artificial intelligence models have shown the potential for providing a reliable diagnostic tool for tooth shade selection, automated restoration design, mapping the preparation finishing line, optimizing the manufacturing casting, predicting facial changes in patients with removable prostheses, and designing removable partial dentures, but they are still in development. Additional studies are needed to further develop and assess their clinical performance.

Association between nonextraction clear aligner therapy and alveolar bone dehiscences and fenestrations in adults with mild-to-moderate crowding.

INTRODUCTION: This study aimed to assess the association between nonextraction clear aligner therapy (CAT) and the presence of alveolar bone dehiscences (ABDs) and fenestrations (ABFs) in adults with mild-to-moderate crowding. METHODS: Cone-beam computed tomography images from 29 adults were obtained before and immediately after nonextraction CAT. Total root lengths were evaluated in axial and cross-sectional slices. Linear measurement for dehiscence (LM-D) was defined as the distance between the alveolar crest to the cementoenamel junction of each root (critical point set at 2 mm). Linear measurement for fenestration (LM-F) was recorded when the defect involved only the apical one-third of a root (critical point set at 2.2 mm). Counts of ABDs/ABFs and magnitudes of LM-Ds/LM-Fs were recorded before and immediately after nonextraction CAT at buccal and lingual root surfaces. Binary logistic regression analyses and repeated measures analyses of variance were performed. RESULTS: Counts of ABDs/ABFs and magnitudes of LM-Ds/LM-Fs increased at most jaw locations and root surfaces. Nonextraction CAT was associated with an increased presence of ABDs and ABFs. Nonextraction CAT was associated with a higher magnitude of LM-Ds but not LM-Fs. CONCLUSIONS: Immediate posttreatment cone-beam computed tomography scans showed that nonextraction CAT is associated with increased ABDs and ABFs in adults with mild-to-moderate crowding.

Sugar-free chewing gum versus conventional analgesic drugs for pain relief with fixed orthodontic appliances. A systematic review and meta-analysis.

OBJECTIVE: To compare the effect of chewing sugar-free gum towards alleviating self-reported orthodontic treatment (OT) pain compared with conventional analgesic drugs (CADs). SEARCH SOURCES: An unrestricted search of indexed databases and manual searching was performed up to September 2021. DATA SELECTION: Randomised controlled trials (RCTs) comparing the impact of chewing gum and CADs on relieving self-reported orthodontic pain were included. DATA EXTRACTION: Data screening, extraction and risk of bias (RoB) assessment were performed by two authors. Meta-analyses were performed using a random-effects model. The quality of available evidence was assessed using the Grades of Recommendation, Assessment, Development and Evaluation approach. RESULTS: Nine RCTs were included. Eight RCTs used the Visual Analogue Scale for self-reported pain assessment, while one RCT used the Numeric Rating Scale. Five RCTs had a high RoB and four RCTs had a moderate RoB. Power analysis for sample size estimation was performed in six RCTs. Separate meta-analyses were performed by pooling quantitative data from five RCTs that compared self-reported orthodontic pain between chewing gum and ibuprofen groups for the following timepoints: baseline; immediately; 2 hours; 6 hours; bedtime; 24 hours; 2 days; 3 days; 5 days; and 7 days after the placement of orthodontic appliances. None of the timepoints individually indicated a difference in self-reported pain scores between chewing sugar-free gum and ibuprofen groups. The overall level of evidence was very low. CONCLUSION: Chewing sugar-free gum is a potentially useful alternative to CADs towards pain alleviation during fixed OT.

Insertion and removal torque of dental implants placed using different drilling protocols: An experimental study on artificial bone substitutes.

PURPOSE: The aim of this in vitro study was to measure the insertion and removal torque values of dental implant replicas inserted into artificial bone blocks using different surgical burs and drilling protocols. MATERIALS AND METHODS: Four types of artificial, polyurethane bone blocks were used with different thicknesses (1 and 2 mm) and densities (soft-1 mm, soft-2 mm, dense-1 mm, and dense-2 mm) of the simulated cortical and cancellous bone, respectively. Each bone construct was drilled with Straumann and Densah drills in both clockwise and counterclockwise directions for a total of 16 experimental conditions. For every scenario, 38 implant replicas were inserted and then removed after 1 min. Outcomes of interest were the insertion and removal torque values which were recorded by a torque meter. ANOVA and Tukey HSD tests were used to assess differences across each combination of drill, direction, and bone type. RESULTS: Densah counterclockwise registered statistically greater values for both insertion and removal torque, followed by Densah clockwise, Straumann counterclockwise, and Straumann clockwise. Increasing insertion and removal torque values were progressively reported for bone type (soft-1 mm, dense-1 mm, soft-2 mm, and dense-2 mm). The mean values of insertion and removal torque were significantly different (p < 0.05) across the four bone types, different burs, and with the two drilling modalities. CONCLUSIONS: Densah bur resulted in significantly greater values of torque compared to the Straumann drills for all the experimental conditions. The thickness of the cortical layer and the counterclockwise drilling direction play a significant role in determining the implant insertion torque.

Survival rates, patient satisfaction, and prosthetic complications of implant fixed complete dental prostheses: a 12-month prospective study.

PURPOSE: To determine the survival rate, incidence of prosthetic complications, and patient satisfaction of implant fixed complete dental prostheses (IFCDPs) after a mean observation period of 1.4 years. MATERIALS AND METHODS: Twenty-eight (28) eligible participants were recruited according to specific inclusion and exclusion criteria. The definitive metal-acrylic resin IFCDPs consisted of titanium bars veneered with acrylic resin and acrylic denture teeth. Prosthodontic complications, divided into major and minor, were monitored. Parameters such as gender, jaw location, bruxism, and occlusal scheme were evaluated. Moreover, a questionnaire was administered throughout the study to assess patient satisfaction. Poisson regression as well as repeated measures ANOVA were used for statistical analysis. RESULTS: Fourteen (14) males and 14 females were enrolled and followed-up at 3, 6, and 12 months. All IFCDPs survived (100% survival rate). The most frequent minor complication was the loss of material used to close the screw access hole (20% out of total complications). The most frequent major complication was chipping of the acrylic denture teeth (77.14% out of total complications). Gender (p = 0.008) and bruxism (p = 0.030) were significant predictors for the total major complications (major wear and major chipping) while occlusal scheme was a significant predictor for major chipping events (p = 0.030). CONCLUSIONS: While IFCDPs demonstrated high prosthetic survival rates, they also exhibited a high number of chipping events of the acrylic veneering material, especially in males, bruxers, and individuals with canine guidance occlusion. However, the occurrence of these prosthetic complications did not negatively affect patient satisfaction.

Evaluation of marginal and internal fit of single crowns manufactured with an analog workflow and three CAD-CAM systems: A prospective clinical study.

PURPOSE: This prospective clinical study evaluated and compared the marginal and internal fit of crowns fabricated with an analog workflow and three different computer-aided design and computer-aided manufacturing (CAD-CAM) systems. MATERIALS AND METHODS: Twenty-five participants in need of a single complete-coverage molar or premolar crown were recruited in the study. Twenty-two completed the study, and three participants dropped out. Teeth were prepared according to a standardized protocol by one operator. For each participant, one final impression was made with polyether material (PP) and three intraoral scanners: CEREC Omnicam (C), Planmeca Planscan (PM), and True Definition (TR). For the PP group, crowns were fabricated with a pressable lithium disilicate ceramic, whereas for the other three groups (C, PM, and TR), crowns were designed and milled with dedicated CAD-CAM systems and materials. Marginal (vertical and horizontal) and internal discrepancies between the crowns and tooth preparation were measured at various locations with digital superimposition software. Data was analyzed for normality with Kolmogorov-Smirnov and Shapiro-Wilk tests and then compared with one-way ANOVA and Kruskal-Wallis tests. RESULTS: Mean vertical marginal gap values were 92.18 ± 141.41 µm (PP), 150.12 ± 138.06 µm (C), 129.07 ± 109.96 µm (PM), and 135.09 ± 112.03 µm (TR). PP group had statistically significantly smaller vertical marginal discrepancy (p = 0.001) than all other groups, whereas no significant difference was detected among the three CAD-CAM systems (C, PM, and TR). Horizontal marginal discrepancies were 104.93 ± 111.96 µm (PP), 89.49 ± 119.66 µm (C), 113.36 ± 128.49 µm (PM), and 136.39 ± 142.52 µm (TR). A significant difference was detected only between C and TR (p < 0.0001). Values for the internal fit were 128.40 ± 49.31µm (PP), 190.70 ± 69.79µm (C), 146.30 ± 57.70 µm (PM), and 168.20 ± 86.67 µm (TR). The PP group had a statistically significant smaller internal discrepancy than C (p < 0.0001) and TR groups (p = 0.001), whereas no significant difference was found compared to the PM group. CONCLUSION: Posterior crowns fabricated with CAD-CAM systems showed vertical margin discrepancy greater than 120 µm. Only crowns fabricated with the conventional methodology had vertical margins below 100 µm. Horizontal marginal discrepancy was different among all groups, and only CEREC CAD-CAM was below 100 µm. Internal discrepancy was less for crowns fabricated with an analog workflow.

Influence of postpolymerization methods and artificial aging procedures on the fracture resistance and flexural strength of a vat-polymerized interim dental material.

STATEMENT OF PROBLEM: The influence of postpolymerization methods and artificial aging procedures on the fracture resistance and flexural strength of additively manufactured interim polymers remains unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effect of the conditions (dry and water- and glycerin-submerged) and time (25, 30, 35, 40, and 45 minutes) of postpolymerization methods with and without artificial aging procedures on the fracture resistance and flexural strength of an additively manufactured interim material. MATERIAL AND METHODS: Bar specimens (25×2×2 mm) were manufactured from an interim resin (NexDent C&B MFH N1) with a 3-dimensional printer (NexDent 5100) as per the manufacturer's recommendations. Three groups were created based on the postpolymerization condition: dry (D group) and submerged in a container with water (W group) or glycerin (G group) inside the ultraviolet polymerization machine (LC-3DPrint Box). Each group was divided into 5 subgroups (D1 to D5, W1 to W5, and G1 to G5) depending on the polymerizing time (25, 30, 35, 40, and 45 minutes) (n=20). Each subgroup was divided into nonaged and aged subgroups. The aged groups were treated in a mastication simulator. Fracture strength was measured on a universal testing machine. The flexural strength was calculated as per International Organization for Standardization (ISO) 10477-2018. The Kolmogorov-Smirnov test demonstrated that data were normally distributed. The 3-way ANOVA test was used to analyze the data (α=.05). RESULTS: A significant main effect was found on the fracture strength analysis for each of the 3 factors: postpolymerization condition (F[2, 449]=81.00, P<.001), treatment duration (F[4, 449]=2.84, P=.024), and aging procedure (F [1, 449] =7.62, P=.006). The only significant 2-way interaction was between postpolymerization condition and treatment duration (F[8, 449]=3.12, P=.002). Furthermore, a significant main effect was found on the flexural strength for each of the 3 factors including postpolymerization condition (F[2, 449]=82.55, P<.001), treatment duration (F[4, 449]=2.85, P=.024), and artificial aging procedure (F[1, 449]=6.72, P=.010). The only significant 2-way interaction was between postpolymerization condition and treatment duration (F[8, 449]=3.33, P=.001). Dry postconditions at 25 minutes and nonaged procedures obtained the significantly highest fracture resistance and flexural strength values. CONCLUSIONS: Postpolymerization conditions and duration time affected the fracture resistance and flexural strength of the additively manufactured interim material assessed. Artificial aging procedures significantly decreased the fracture resistance and flexural strength of the additively manufactured interim dental material.

Accuracy of a patient 3-dimensional virtual representation obtained from the superimposition of facial and intraoral scans guided by extraoral and intraoral scan body systems.

STATEMENT OF PROBLEM: A patient 3-dimensional virtual representation aims to facilitate the integration of facial references into treatment planning or prosthesis design procedures, but the accuracy of the virtual patient representation remains unclear. PURPOSE: The purpose of the present observational clinical study was to determine and compare the accuracy (trueness and precision) of a virtual patient obtained from the superimposition procedures of facial and intraoral digital scans guided by 2 scan body systems. MATERIAL AND METHODS: Ten participants were recruited. An intraoral digital scan was completed (TRIOS 4). Four fiduciary markers were placed in the glabella (Gb), left (IOL) and right infraorbital canal (IOR), and tip of the nose (TN). Two digitizing procedures were completed: cone beam computed tomography (CBCT) (i-CAT FLX V-Series) and facial scans (Face Camera Pro Bellus) with 2 different scan body systems: AFT (ScanBodyFace) and Sat 3D (Sat 3D). For the AFT system, a reference facial scan was obtained, followed by a facial scan with the participant in the same position as when capturing the CBCT scan. For the Sat 3D system, a reference facial scan was recorded, followed by a facial scan with the patient in the same position as when capturing the CBCT scan. The patient 3-dimensional representation for each scan body system was obtained by using a computer program (Matera 2.4). A total of 14 interlandmark distances were measured in the CBCT scan and both 3-dimensional patient representations. The discrepancies between the CBCT scan (considered the standard) and each 3-dimensional representation of each patient were used to analyze the data. The Kolmogorov-Smirnov test revealed that trueness and precision values were not normally distributed (P<.05). A log10 transformation was performed with 1-way repeated-measures MANOVA (α=.05). RESULTS: The accuracy of the virtual 3-dimensional patient representations obtained by using AFT and Sat 3D systems showed a trueness ranging from 0.50 to 1.64 mm and a precision ranging from 0.04 to 0.14 mm. The Wilks lambda detected an overall significant difference in the accuracy values between the AFT and Sat 3D systems (F=3628.041, df=14, P<.001). A significant difference was found in 12 of the 14 interlandmark measurements (P<.05). The AFT system presented significantly higher discrepancy values in Gb-IOL, TN-IOR, IOL-IOR, and TN-6 (P<.05) than in the Sat 3D system. The Sat 3D system had a significantly higher discrepancy in Gb-TN, TN-IOL, IOL-3, IOL-6, TN-8, TN-9, TN-11, IOR-11, and IOR-14 (P<.05) than in the AFT system. The Wilcoxon signed-rank test did not detect any significant difference in the precision values between the AFT and Sat 3D systems (Z=-0.838, P=.402). CONCLUSIONS: The accuracy of the patient 3-dimensional virtual representations obtained using AFT and Sat 3D systems showed trueness values ranging from 0.50 to 1.64 mm and precision values ranging from 0.04 to 0.14 mm. The AFT system obtained higher trueness than the Sat 3D system, but both systems showed similar precision values.

Adhesion of veneering porcelain to cobalt-chromium dental alloys processed with casting, milling, and additive manufacturing methods: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Selective laser melting (SLM) additive manufacturing (AM) technologies provide an alternative to conventional casting and milling procedures in fabricating metal-ceramic dental prostheses. However, the quality of porcelain bond strength to the SLM AM cobalt-chromium (Co-Cr) metal framework of a dental restoration is unclear. PURPOSE: The purpose of this systematic review and meta-analysis was to identify in vitro studies that reported the porcelain bond strength to SLM AM Co-Cr dental metal alloys and compare the porcelain bond strength values to cast, milled, and additively manufactured Co-Cr dental alloys. MATERIAL AND METHODS: An electronic systematic review was performed in different databases: MEDLINE/PubMed, EMBASE, World of Science, Cochrane, and Scopus. A manual search was also conducted. Studies that reported the porcelain bond strength to SLM Co-Cr metal alloys and in the English language were included. Two investigators evaluated the quality assessment of the studies by applying the JBI critical appraisal checklist for quasi-experimental studies (nonrandomized experimental studies). A third investigator was consulted to resolve lack of consensus. Two subgroups were created based on the test used, 3-point bend and shear bond strength tests. The porcelain bond strength of cast, milled, and AM Co-Cr dental alloys were compared. The I2 statistic and its associated P value were used to assess the heterogeneity between studies. The Eger test was used for determining significance of the funnel pots. RESULTS: A total of 216 studies were collected from the electronic and manual searches. After independently evaluating the titles and abstracts by the reviewers, 26 articles were identified. Three of these were excluded after full-text revision. The porcelain bond strength comparison between the cast and AM alloys for the 3-point bend subgroup revealed a significant result for overall effect (P<.001) favoring the SLM method with considerable heterogeneity (I2=83%, P<.001). Furthermore, the porcelain bond strength comparison between cast and milled alloys for the shear bond strength subgroup revealed a significant test for overall effect (P=.04) favoring milled procedures with a nonsignificant unimportant heterogeneity (I2= 0%, P<.47) and for the 3-point bend subgroup (P<.001) favoring milled specimens with a significant considerable heterogeneity (I2=79%, P<.001). CONCLUSIONS: The metal manufacturing method had no effect on the porcelain bond strength to Co-Cr dental metal alloys.

Implant survival and biologic complications of implant fixed complete dental prostheses: An up to 5-year retrospective study.

STATEMENT OF PROBLEM: Limited information is available on the association between prosthesis-associated risk factors and biologic complications for patients with implant fixed complete dental prostheses (IFCDPs). PURPOSE: The purpose of this retrospective study was to assess the implant survival and biologic complications of IFCDPs up to 5 years of follow-up. MATERIAL AND METHODS: Patients who had received IFCDPs between August 1, 2009 and August 1, 2014 were identified through an electronic health record review. Those who consented to participate in the study attended a single-visit study appointment. Clinical and radiographic examinations, intraoral photographs, and peri-implant hard and soft tissues parameters were assessed. Only prostheses which could be removed during the study visit were included. Associations between biologic complications and prosthetic factors, such as time with prosthesis in place, prosthesis material, number of implants, cantilever length, and type of prosthesis retention, were assessed. RESULTS: A total of 37 participants (mean ±standard deviation age 62.35 ±10.39 years) with 43 IFCDPs were included. None of the implants had failed, leading to an implant survival of 100% at 5.1 ±2.21 years. Ten of the prostheses were metal-ceramic (Group MC) and 33 were metal-acrylic resin (Group MR). Minor complications were more frequent than major ones. Considering minor complications, peri-implant mucositis was found in 53% of the implant sites, more often in the maxilla (P=.001). The most common major biologic complication was peri-implantitis, which affected 4.0% of the implants, more often in the mandible (P=.025). Peri-implant soft tissue hypertrophy was present 2.79 times more often (95% CI: 1.35 - 5.76, P<.003) around implants supporting metal-acrylic resin prostheses than metal-ceramic ones, with the former type also showing significantly more plaque accumulation (P<.003). CONCLUSIONS: Biologic complications such as soft tissue hypertrophy and plaque accumulation were more often associated with metal-acrylic resin prostheses. Peri-implant mucositis occurred more often under maxillary IFCDPs, while peri-implantitis appeared more common around mandibular implants.

Artificial intelligence applications in restorative dentistry: A systematic review.

STATEMENT OF PROBLEM: Artificial intelligence (AI) applications are increasing in restorative procedures. However, the current development and performance of AI in restorative dentistry applications has not yet been systematically documented and analyzed. PURPOSE: The purpose of this systematic review was to identify and evaluate the ability of AI models in restorative dentistry to diagnose dental caries and vertical tooth fracture, detect tooth preparation margins, and predict restoration failure. MATERIAL AND METHODS: An electronic systematic review was performed in 5 databases: MEDLINE/PubMed, EMBASE, World of Science, Cochrane, and Scopus. A manual search was also conducted. Studies with AI models were selected based on 4 criteria: diagnosis of dental caries, diagnosis of vertical tooth fracture, detection of the tooth preparation finishing line, and prediction of restoration failure. Two investigators independently evaluated the quality assessment of the studies by applying the Joanna Briggs Institute (JBI) Critical Appraisal Checklist for Quasi-Experimental Studies (nonrandomized experimental studies). A third investigator was consulted to resolve lack of consensus. RESULTS: A total of 34 articles were included in the review: 29 studies included AI techniques for the diagnosis of dental caries or the elaboration of caries and postsensitivity prediction models, 2 for the diagnosis of vertical tooth fracture, 1 for the tooth preparation finishing line location, and 2 for the prediction of the restoration failure. Among the studies reviewed, the AI models tested obtained a caries diagnosis accuracy ranging from 76% to 88.3%, sensitivity ranging from 73% to 90%, and specificity ranging from 61.5% to 93%. The caries prediction accuracy among the studies ranged from 83.6% to 97.1%. The studies reported an accuracy for the vertical tooth fracture diagnosis ranging from 88.3% to 95.7%. The article using AI models to locate the finishing line reported an accuracy ranging from 90.6% to 97.4%. CONCLUSIONS: AI models have the potential to provide a powerful tool for assisting in the diagnosis of caries and vertical tooth fracture, detecting the tooth preparation margin, and predicting restoration failure. However, the dental applications of AI models are still in development. Further studies are required to assess the clinical performance of AI models in restorative dentistry.

Influence of low-level-laser therapy on the stability of orthodontic mini-screw implants. A systematic review and meta-analysis.

BACKGROUND: The influence of low-level-laser therapy (LLLT) on the stability of orthodontic mini-screw implants (MSIs) has not been systematically reviewed. OBJECTIVES: The aim was to assess the influence of LLLT on the stability of orthodontic MSIs. METHODS: An unrestricted search of indexed databases was performed. SELECTION CRITERIA: Randomized controlled clinical trials (RCTs) investigating the influence of LLLT on orthodontic MSI stability. DATA COLLECTION AND ANALYSIS: Two authors independently performed study retrieval and selection, and data extraction. The risk of bias (RoB) of individual studies was assessed using the Cochrane RoB Tool for RCTs. Meta-analyses were performed separately for RCTs using periotest and resonance frequency analysis (RFA) to measure MSI stability; and a random effects model was applied. Subgroup analyses were performed based on the time-points of MSI stability evaluation. The quality of available evidence was evaluated using the Grades of Recommendation, Assessment, Development, and Evaluation approach. RESULTS: Initially, 1332 articles were screened. Six RCTs with a split-mouth design were included. The periotest was used in 4 RCTs and 2 RCTs used RFA to measure MSI stability. All RCTs had a low RoB. Subgroup analyses based on periotest indicated that MSIs treated with LLLT had significantly higher stability than untreated MSIs at 21 and 30 days [weighted mean difference (MD) = -2.76, confidence interval (CI): [-4.17, -1.36], P-value = 0.0001) and at 60 days (weighted MD = -3.47, CI: [-4.58, -2.36], P < 0.00001); and the level of certainty was high. Subgroup analyses based on RFA showed higher stability of MSIs treated with than without LLLT at 56 and 60 days (standardized MD = 0.82, CI: [0.32, 1.32], P = 0.001), and at 70 and 90 days (standardized MD = 0.86, CI: [0.36, 1.36], P = 0.0007); and the level of certainty was moderate. LIMITATIONS: Due to limited number of relevant studies, it was not possible to perform sensitivity analysis, subgroup analyses for patient and intervention-related characteristics, and reporting biases assessment. CONCLUSIONS: The role of LLLT on the secondary stability of MSIs placed in patients undergoing OT remains debatable. CLINICAL TRIAL REGISTRATION: PROSPERO (CRD42021230291).

Surface Roughness and Bond Strength of Resin Composite to Additively Manufactured Zirconia with Different Porosities.

PURPOSE: To investigate the bond strength of resin cement to additively manufactured (AM) zirconia with different porosities when compared to milled zirconia. MATERIALS AND METHODS: A 12 × 5 mm disk virtual design file was used to fabricate a total of 48 disks divided into 4 groups: 3 groups were AM with different porosities including 0%-porosity (AMZ0 group), 20%-porosity (AMZ20 group), and 40%-porosity (AMZ40 group), and 1 milled zirconia (control or CNCZ group). The dimensions of all specimens were measured using a digital caliper. A 3D- confocal laser scanner was used to analyze surface morphology and measure the surface roughness (Sa), followed by SEM analysis. Tensile bond strength of composite resin cement to specimens was measured before and after aging procedures using a universal testing machine (n = 10). Failure modes were evaluated under a light microscope. Volumetric change data was analyzed using one-way ANOVA, and two-way ANOVA was used to compare bond strength values (α = 0.05). RESULTS: There was a significant difference in volumetric changes among the groups. The CNCZ group showed the least changes in diameter 0.027 ± 0.029 mm and thickness 0.030 ± 0.012 mm and AM zirconia with 40% porosity showed the most volumetric changes in diameter 5.237 ± 0.023 mm. ANOVA test indicated an overall significant difference in surface roughness across all groups (F = 242.6, p < 0.001). The CNCZ group showed the highest mean Sa of 1.649 ± 0.240 µm, followed by AMZ40 group with Sa of 0.830 ± 0.063 µm, AMZ20 group with Sa of 0.780 ± 0.070 µm, and the AMZ0 group with Sa of 0.612 ± 0.063 µm. Two-way ANOVA showed significant difference in bond strength between the CNCZ group 12.109 ± 3.223 MPa and the AMZ0 group 8.629 ± 0.914 MPa, with significant pretest failures in specimens with porosities. Thermal cycling methods reduced the bond strength non-significantly in CNCZ group with no effect in the AMZ0 group. CONCLUSION: Milled zirconia had a higher surface roughness and bond strength to composite resin cement than AM zirconia, and porosities in AM zirconia decreased the bond strength with significant pretest failures.