Effect of 3D printer, implant analog system, and implant angulation on the accuracy of analog position in implant casts.

OBJECTIVES: To evaluate the accumulative effect of 3D printer, implant analog systems, and implant angulation on the accuracy of analog position in implant casts. METHODS: A reference cast, presenting a case of a three-unit implant-supported prosthesis, was scanned with a coordinate measurement machine, producing the first reference data set (CMM, n = 1). The second reference data set (n = 10) was prepared using an intraoral scanner (IOS) (Trios4). Test quadrant casts were produced using three DLP type 3D printers, Max (MAX UV385), Pro (PRO 4K65 UV), and Nex (NextDent 5100), and three implant analog systems, El (Elos), Nt (Nt-trading), and St (Straumann) (n = 90). Stone casts were also produced via analog impressions (Stone, n = 10). After digitization, the accuracy of 3D distance, local angulation (angle between implants) and global angulation (angle between the implant center axis and an axis perpendicular to the global plane) was evaluated by comparing the reference (CMM, IOS), test (3D print), and control (Stone) groups using metrology software. Data were statistically analyzed using three-way ANOVA and Tukey`s tests (α=0.05). RESULTS: IOS was truer in 3D implant distance and more precise in capturing local angulation than Stone (p ≤ 0.05). Other measurements were similar between both groups (p > 0.05). The amount of error introduced in the workflow by IOS and 3D printing was mostly similar (p > 0.05). 3D printed casts had similar or even higher accuracy than Stone group (p > 0.05). In most cases, higher trueness was achieved when using PRO 4K65 UV 3D printer and Elos implant analog system (p ≤ 0.05). CONCLUSION: 3D printer, implant analog system, and implant angulation have a significant effect on the accuracy of analog position in implant casts. Limited-span implant-supported cases could be reproduced digitally with similar accuracy as conventional methods. CLINICAL SIGNIFICANCE: A fully digital workflow with a carefully selected 3D printer and implant analog system can increase the accuracy of digitally produced implant casts with comparable accuracy to conventional workflow.

Effect of Different Intraoral Scanners on the Accuracy of Bite Registration in Edentulous Maxillary and Mandibular Arches.

OBJECTIVES: The objective of this study was to use in vitro models to examine the bite registration accuracy of four different intraoral scanners (IOS) for edentulous maxillary and mandibular arches. The objective was to assess the trueness and precision of the IOS and determine if there were significant differences between them. METHODS: An Asiga Max UV 3D printer was used to print maxillary and mandibular edentulous models based on the shape of Frasaco models (artificial dental arch models). Four dental implants were placed symmetrically in both models using Straumann BLT RC implants. Digital impressions were taken with Primescan, Trios 3, Trios 4, and Medit i500 intraoral scanners (n = 10 for each IOS). Digital bite registrations were made, and scanning data was exported in STL format. The accuracy of the interarch distance (the distance between the metrological spheres attached to the mandibular and maxillary models) was estimated for each IOS. RESULTS: The results showed significant differences in trueness and precision between different IOS (p <.05), except Medit i500 and Trios 3 (p >.05). Primescan provided the most accurate results, followed by Medit i500, Trios 3, and Trios 4, respectively. CONCLUSIONS: within the limitations of this study, the IOS type affects the accuracy of interocclusal bite registration in in vitro design. Only Primescan achieved clinically acceptable accuracy for the interocclusal recording of edentulous arches. CLINICAL RELEVANCE: The comparison of the accuracy of bite registration between different intraoral scanners will help increase the efficiency of the clinical application of digitalized interarch registration.

Reliability of clinical examination methods for postoperative pain after primary root canal treatment.

Background/purpose: Clinical test results may have lower reliability due to the varying range of test stimulation or patient subjectiveness. This study aimed to verify a reliable clinical test method by comparing pain intensity levels of a tooth at rest, during function, and after the clinical tests of percussion and chewing. Materials and methods: A total of 36 asymptomatic necrotic teeth that required root canal treatment, one in each patient, were included. All treatment procedures were performed in a single visit by an experienced endodontist. Patients were asked to mark their pain levels on a vertical visual analog scale (VAS) while the relevant tooth was at rest and during function 24 h after the treatment. In addition, patients marked their pain levels after the clinical tests of percussion and chewing. Finally, the pain levels were compared using Pearson's correlation for the reliability of the test methods at a significance level of 95%. Results: The postoperative pain levels measured during the clinical tests and functions were significantly higher than the pain levels at rest (P < 0.05). The pain levels after percussion tests were significantly higher than that during the function and chewing tests (P < 0.05). Pain intensity during the function was simulated with a higher correlation when using the chewing strip method rather than the percussion method. Conclusion: The bite test using the chewing strips as a pain intensity assessment can mimic the actual postoperative pain experience, whereas the percussion test fails to provide the accuracy of this pain experience.

Does radiation therapy affect adhesion of tricalcium silicate cements to root dentin?

OBJECTIVE: This study aimed to analyze the effect of irradiation on the push-out bond strength of mineral trioxide aggregate (MTA) and Biodentine to radicular dentin. METHODOLOGY: A total of 60 extracted mature human teeth with single root canals were categorized into two groups (irradiated and non-irradiated) (n=30). Each group was further divided into two sub-groups based on cements used (Biodentine and MTA). Then, a cumulative radiation dose of 60 Gy was divided into 30 fractions (two Gy for every fraction) and administered for five successive days per week over six weeks. Obturation was then performed using MTA and Biodentine. Afterwards, 1.5 mm thick horizontal sections were procured from the middle one-third of all the specimens and then subjected to push-out bond test. Results were analyzed using one-way analysis of variance with post-hoc Tukey's test. RESULTS: The bond strength of Biodentine and MTA to irradiated teeth was lower than non-irradiated teeth. Highest push-out bond strength was observed in non-irradiated specimens filled with Biodentine (p=0), followed by irradiated specimens filled with Biodentine (p=0); non-irradiated specimens filled with MTA (p=0); and irradiated specimens filled with MTA (p=0.9). CONCLUSION: The push-out bond strength of Biodentine and MTA to root canal dentin decreased significantly post irradiation.

Comparison of wear and fracture resistance of additively and subtractively manufactured screw-retained, implant-supported crowns.

STATEMENT OF PROBLEM: Additively manufactured resins indicated for fixed definitive prostheses have been recently marketed. However, knowledge on their wear and fracture resistance when fabricated as screw-retained, implant-supported crowns and subjected to artificial aging is limited. PURPOSE: The purpose of this in vitro study was to evaluate the volume loss, maximum wear depth, and fracture resistance of screw-retained implant-supported crowns after thermomechanical aging when fabricated using additively and subtractively manufactured materials. MATERIAL AND METHODS: Two additively manufactured composite resins (Crowntec [CT] and VarseoSmile Crown Plus [VS]) and 2 subtractively manufactured materials (1 reinforced composite resin, Brilliant Crios [BC] and 1 polymer-infiltrated ceramic network, Vita Enamic [EN]) were used to fabricate standardized screw-retained, implant-supported crowns. After fabrication, the crowns were cemented on titanium base abutments and then tightened to implants embedded in acrylic resin. A laser scanner with a triangular displacement sensor (LAS-20) was used to digitize the preaging state of the crowns. Then, all crowns were subjected to thermomechanical aging (1.2 million cycles under 50 N) and rescanned. A metrology-grade analysis software program (Geomagic Control X 2020.1) was used to superimpose postaging scans over preaging scans to calculate the volume loss (mm3) and maximum wear depth (mm). Finally, all crowns were subjected to a fracture resistance test. Fracture resistance and volume loss were evaluated by using 1-way analysis of variance and Tukey Honestly significant difference (HSD) tests, whereas the Kruskal-Wallis and Dunn tests were used to analyze maximum wear depth. Chi-square tests were used to evaluate the Weibull modulus and characteristic strength data (α=.05). RESULTS: Material type affected the tested parameters (P<.001). CT and VS had higher volume loss and maximum wear depth than BC and EN (P<.001). EN had the highest fracture resistance among tested materials (P<.001), whereas BC had higher fracture resistance than CT (P=.011). The differences among tested materials were not significant when the Weibull modulus was considered (P=.199); however, VE had the highest characteristic strength (P<.001). CONCLUSIONS: Additively manufactured screw-retained, implant-supported crowns had higher volume loss and maximum wear depth. All materials had fracture resistance values higher than the previously reported masticatory forces of the premolar region; however, the higher characteristic strength of the subtractively manufactured polymer-infiltrated ceramic network may indicate its resistance to mechanical complications.

Effect of Various Beverages on Adhesion of Repaired CAD/CAM Restorative Materials.

(1) Background: The purpose of this study was to determine the effect of commonly consumed beverages on the bond strength of three different computer-aided design-computer-aided manufacturing (CAD/CAM) resin-ceramic hybrid materials repaired with resin-based composite (RBC) materials. (2) Materials and Methods: Rectangular prism specimens (N = 138) measuring 6 mm × 5 mm × 2 mm were obtained from GC Cerasmart (GC), Lava Ultimate (LU), and Vita Enamic (VE) blocks. These blocks were polished and then subjected to thermal cycling (10,000 cycles, 5 °C to 55 °C). After the surface treatment was applied, the average surface roughness value was measured. All the surfaces were repaired with RBC. Thermal cycling was performed for the second time. Each group was then distributed into three subgroups according to the beverage used: tea (t), cola (c), and distilled water (0) (n = 15). The specimens were stored in these solutions for 28 days and then subjected to the shear bond strength (SBS) test. Statistical analysis was performed using a two-way ANOVA test with Bonferroni adjustment. (3) Results: The surface roughness of the materials presented no significant difference after different surface treatments (p > 0.05). No significant difference was observed among the materials (p > 0.05). Tea and cola presented similar SBS values (p > 0.05). Both were significantly lower than distilled water (p < 0.001, p < 0.001, respectively). (4) Conclusions: Consumption of beverages reduces the bond strength in surfaces repaired with RBC to CAD/CAM resin-ceramic hybrid materials. (5) Clinical Significance: Repairing damaged resin matrix dental restorations with RBC is advantageous in terms of time and cost by achieving adequate bond strengths. Frequently consumed beverages reduce the bond strength of repaired CAD/CAM resin-ceramic hybrid materials.

Assessment of the canal anatomy of the premolar teeth in a selected Turkish population: a cone-beam computed tomography study.

BACKGROUND: Teeth may have additional roots and a different number of root canals. Overlooked root canals may cause endodontic failure. The aim of this study was to investigate the prevalence of root canals and the number of roots of premolars in a selected Turkish population. MATERIALS AND METHODS: A total of 2,570 teeth from 1,438 patients were evaluated. The cone-beam computed tomography scans of 1,055 maxillary and 1,515 mandibular premolars were examined. RESULTS: Type IV root canal morphology was observed most frequently in maxillary first premolars (77%), and the rates of single and double channel formations were very similar (51% and 49%, respectively). Of the second maxillary premolars, 57.4% had Type I morphology, and 89.9% of the teeth were single-rooted, while 68.6% had a single root canal. The most common formation was Type I (85%) among mandibular first premolars, and a single root was observed in 95.6% of these teeth. In addition, 87% of the mandibular first premolars had a single root canal. The second mandibular premolars mostly had Type I (95.4%) formation, and 99.3% of the teeth were single-rooted, while 96.9% had a single root canal. CONCLUSION: According to our findings, 51% of maxillary first premolars had a single root, 79.4% had two root canals, and 77% had Type IV (77%) formation. Maxillary second premolars mostly had Type I formation. In addition, a single root and single root canal formation were most common. Mandibular first premolars generally had a single root and single root canal formation, but 13% had two root canals, and 6.4% had Type V formation. More than 95% of mandibular second premolars had Type I formation.

In-Vitro Evaluation of Photofunctionalized Implant Surfaces in a High-Glucose Microenvironment Simulating Diabetics.

The present study aimed to assess the efficacy of photofunctionalization on commercially available dental implant surfaces in a high-glucose environment. Discs of three commercially available implant surfaces were selected with various nano- and microstructural alterations (Group 1-laser-etched implant surface, Group 2-titanium-zirconium alloy surface, Group 3-air-abraded, large grit, acid-etched surface). They were subjected to photo-functionalization through UV irradiation for 60 and 90 min. X-ray photoelectron spectroscopy (XPS) was used to analyze the implant surface chemical composition before and after photo-functionalization. The growth and bioactivity of MG63 osteoblasts in the presence of photofunctionalized discs was assessed in cell culture medium containing elevated glucose concentration. The normal osteoblast morphology and spreading behavior were assessed under fluorescence and phase-contrast microscope. MTT (3-(4,5 Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and alizarin red assay were performed to assess the osteoblastic cell viability and mineralization efficiency. Following photofunctionalization, all three implant groups exhibited a reduced carbon content, conversion of Ti4+ to Ti3+, increased osteoblastic adhesion, viability, and increased mineralization. The best osteoblastic adhesion in the medium with increased glucose was seen in Group 3. Photofunctionalization altered the implant surface chemistry by reducing the surface carbon content, probably rendering the surfaces more hydrophilic and conducive for osteoblastic adherence and subsequent mineralization in high-glucose environment.

Endodontic management of a double-type IIIB dens invaginatus in a vital maxillary central incisor aided by CBCT: A case report.

Type IIIB dens invaginatus presents with diagnostic and treatment related challenges when in need of endodontic management as a consequence of its complex anatomy, especially when presented in a vital tooth with a periapical lesion. Apical periodontitis associated with two type IIIB invaginations in a central maxillary incisor of a 10-year-old patient was diagnosed. A cone-beam computed tomography (CBCT) scan provided essential diagnostic information and steered the treatment plan. The two invaginations were separate, with no communication between them and the pulp. The pulp appeared vital and non-inflamed. Endodontic treatment of the invaginations was carried out without intervention in the pulp. A 4-month follow-up periapical radiograph showed significant shrinkage of the lesion and a 2-year follow-up CBCT scan confirmed its complete healing. The pulp remains vital, responding normally to sensitivity tests. This outcome indicates that preserving the pulp's vitality is achievable through timely diagnosis.

When to install the endodontic post? First visit with root canal filling versus a separate second visit for post-restoration: A randomized controlled trial.

BACKGROUND: The vibrations created by post-space preparation during the first visit for endodontic treatment could have a significant effect on the intensity of post-operative pain than that association with post-space preparation at the second appointment. OBJECTIVE: The aim of this study was to evaluate the effect of vibrations generated during post-installation, on post-operative pain in endodontically treated teeth. METHODS: One hundred patients with asymptomatic teeth requiring primary root canal treatment and post-installation were enrolled in this study. Fifty patients underwent endodontic treatment with post-installation at the first visit (group 1), while the remaining 50 patients underwent post-installation at the second visit (group 2). The intensity of post-operative pain in both groups was evaluated 1, 2, 3 days and 1 week after the first visit using the visual analogue scale. The time required to achieve complete pain relief for each patient was also recorded. The patients' age, sex, tooth type, size of the periapical lesion and time required for complete post-operative pain relief for each tooth were recorded. RESULTS: The pain intensity score was significantly higher in group 1 than group 2 (P < .05). No significant differences were observed in parameters such as sex, tooth type, jaw and size of the periapical lesion (P > .05), whereas age had a significant effect on the post-operative pain scores (P < .05). CONCLUSION: Vibrations occurring during post-installation on the same visit as that of root canal filling may increase the post-operative pain.

The effect of pain intensity levels and clinical symptoms on the treatment preferences of patients with endodontically involved teeth: A preliminary cross-sectional study.

PURPOSE: This study aimed to evaluate the effect of pain intensity levels and clinical symptoms on the treatment preferences of patients with endodontically involved teeth in a local Turkish population. SUBJECTS AND METHODS: A total of 30 patients with symptomatic teeth requiring non-surgical root canal treatment were included in the study. The patients' demographic (age, gender, and education level) and diagnostic data (tooth type, pain intensity, response to percussion and palpation, presence of referred pain, and diagnosis) were analyzed. Data on the patients' explicit preferences (requested treatment, whether they are willing to accept a proposed extraction, choice of treatment if an anterior tooth was involved, and choice of treatment if the pain was not severe) as well as previous root canal treatment experiences were also analyzed. Pain intensity levels were evaluated using the Visual Analog Scale. RESULTS: Pain intensity levels had a significant effect on the treatment requested by the patient (p=0.001). Among the patients who requested extraction upon referral to the clinic, the rate of those who reported that they would not accept extraction if the pain was located in an anterior tooth was significantly lower than that of patients stating that they would refuse (p=0.039). The presence of referred pain also had a significant effect on the requested treatment (p=0.001). CONCLUSION: The intensity of pain and the presence of referred pain influence patients' treatment preferences.

Postoperative pain intensity associated with the use of different nickel-titanium shaping systems during single-appointment endodontic retreatment: a randomized clinical trial.

OBJECTIVE: The objective of this randomized clinical trial was to compare the effect of different NiTi shaping systems on postoperative pain after single-appointment nonsurgical endodontic retreatment. METHOD AND MATERIALS: Between September 2016 and December 2016, 99 patients with asymptomatic root canal-treated teeth requiring nonsurgical endodontic retreatment were randomly divided into three groups (n = 33 per group). After removing previous root canal filling, instrumentation was performed using One Shape, Revo-S, and WaveOne systems in groups 1, 2, and 3, respectively. Postoperative pain intensity was assessed at 6, 12, 18, 24, 48, and 72 hours, 7 days, and 1 month after the retreatment. Data were analyzed using one-way ANOVA and Mann-Whitney U and Kruskal-Wallis tests (alpha = .01). RESULTS: Up to 72 hours, postoperative pain was significantly less in group 1 than in groups 2 and 3 (P < .01). From 72 hours to 7 days, postoperative pain was significantly less in groups 1 and 2 (P > .05), compared to group 3 (P < .01). At 1 month, postoperative pain was not significantly different among all three groups (P > .05). Postoperative pain was the highest with WaveOne group. CONCLUSIONS: Since One Shape and Revo-S are both based on the rotational approach and WaveOne on reciprocal approach, less incidence of postoperative pain intensity with One Shape and Revo-S in single-appointment nonsurgical endodontic retreatment could be associated with the motion type during root canal shaping.

Clinical outcomes of non-surgical multiple-visit root canal retreatment: a retrospective cohort study.

This study aimed to investigate the effects of several clinical factors on the success and survival rates of multiple-visit non-surgical root canal (NSRC) retreatment. Failed endodontically treated 236 teeth in 161 patients (18-72 years, 48% males; and 52% females) were retreated between March 2014 and December 2015 and were enrolled in this study. Two calibrated examiners evaluated the preoperative, intraoperative, and postoperative outcomes using the periapical index (PAI) scores. The teeth were classified as healed (healthy apical tissues, PAI ≤ 2, no signs or symptoms), healing (no signs and symptoms, PAI > 2 but reduced from the initial PAI score), and not-healed (presence of apical periodontitis, signs and/or symptoms, PAI > 2). The teeth scored as healed and healing was considered to be successful, while the not-healed ones were considered as failures. Of the 236 teeth, 135 (57.3%) in 103 patients (63.9%) were lost to follow-up, yielding to follow-up of 101 teeth (42.7%) in 58 patients (36%). Three teeth were extracted yielding to an overall success rate of 85.1%, at a mean observation time of 33.8 months. The teeth with periapical lesions < 5 mm had an 88.6% success rate, while those ≥ 5 mm had an 80% success rate (P > 0.05). While, age, gender, preoperative, intraoperative, and postoperative factors did not significantly affect the outcomes (P > 0.05), tooth type significantly affected the success rate (P < 0.05). The most frequently failed teeth were the mandibular first molars (P < 0.05). Based on these results, the multiple-visit NSRC retreatment exhibited a favorable success rate and could be offered for the endodontically failed teeth.

A clinical study on single-visit root canal retreatments on consecutive 173 patients: frequency of periapical complications and clinical success rate.

OBJECTIVES: This study assessed the outcome measures of single-visit root canal retreatments and frequency of periapical complications considering preoperative, intraoperative and postoperative factors. MATERIALS AND METHODS: Between November 2011 and December 2012, in 173 patients, a total of 234 endodontically treated teeth were retreated in a single appointment by one experienced endodontist. Five teeth were extracted and 119 teeth were lost to follow-up yielding to 110 teeth (47 %) to be examined by two calibrated examiners for the outcome of healing (periapical index score-PAI ≤2; no signs or symptoms) or non-healing (presence of apical periodontitis-PAI >2; signs or symptoms). Preoperative, intraoperative and postoperative factors were evaluated for their association with the outcome. Data were analysed using Fisher's exact and Fisher-Freeman Halton tests for bivariate analysis to identify potential outcome predictors. Logistic regression models were used for multivariate analysis to determine significant outcome predictors. RESULTS: Mean observation time was 29 months. Follow-up assessment revealed 100 teeth (90.9 %) as healed and 10 teeth (9.1 %) non-healed. Age, gender, tooth type and preoperative (pain, periodontal defects, root filling density and length), intraoperative (sealer extrusion) and postoperative (type of coronal restorations) factors did not significantly affect the outcome (p > 0.05). Preoperative periradicular lesions with diameters less than 5 mm presented significantly better outcome than larger lesions (p < 0.05; odds ratio (OD) 6; 95 % CI 1.45-24.85). Logistic regression model showed an increased risk of non-healing for the parameter of preoperative periradicular lesions with diameters larger than 5 mm (OD 6.42; 95 % CI 1.51-27.27). CONCLUSIONS: Single-appointment root canal retreatments presented a favourable success rate. Only preoperative lesion size had a significant effect on the outcome where the lesions smaller than 5 mm performed significantly better healing. CLINICAL RELEVANCE: Single-appointment root canal retreatments could be considered as a viable treatment option for orthograde retreatment cases with periradicular lesion size smaller than 5 mm.

Differences in aluminum equivalent values of endodontic sealers: conventional versus digital radiography.

The aims of this study were to compare film and digital radiography in assessing the radiopacities of root canal sealers and to establish the relation in aluminum equivalent values of different methods. Standard disks of 5 different sealers were exposed together with an aluminum step wedge by using occlusal films and storage phosphor plates. Optical density of the sealers was evaluated by transmission densitometry, and mean gray values were determined by digital analysis. The data were analyzed by using two-way analysis of variance (P = .05). Pairwise comparisons were made by using Tukey post hoc and paired t tests (P = .05). The order from the most radiopaque to the most radiolucent sealer was the same for both methods; however, aluminum equivalent values determined by transmission densitometry were significantly higher (P < .01). Aluminum equivalent values of the 2 radiographic methods were 7%-20% different. The International Standards Organization standard for the radiopacity of dental root canal sealing materials needs modifications for digital systems.

The effect of three different sealers on the radiopacity of root fillings in simulated canals.

OBJECTIVE: The aim of this study was to investigate the effect of 3 root canal sealers on radiopacity of root fillings in simulated canals by means of direct digital radiography. STUDY DESIGN: Thirty simulated root canals in transparent acrylic blocks were prepared with a 4% tapered, size 25 instrument. A single 4% tapered, size 25 gutta-percha cone was inserted into each canal. Standardized images of the blocks with an aluminum step-wedge were obtained by using Digora storage phosphor plates. Then, 3 root canal sealers (Roeko, Diaket, Pulpdent) were mixed according to the manufacturers' instructions. The gutta-percha cones were completely coated with one of the sealers and placed in the identical canal to the full working length. The images of the blocks were reobtained after sealer application. The mean gray values (MGVs) of root fillings were measured with or without the sealer at 3 different levels (1 mm, 6 mm, and 11 mm from apex) by using the Image Tool program. Each MGV measurement was then converted to its aluminum equivalent by means of the step-wedge values. A paired t test was used for statistical analysis. RESULTS: RoekoSeal caused a significant decrease in the radiopacity of the root fillings at the 1-mm level (P < 0.01). Diaket and Pulp Canal Sealer (PCS) increased the radiopacity of the fillings at all levels significantly (P < 0.01) except 6- and 11-mm levels of the Diaket specimens (P > 0.05). CONCLUSION: The type and the thickness of root canal sealers can influence the radiopacity of the root fillings.