Marginal adaptation of customized gutta percha cone with calcium silicate based sealer versus MTA and biodentine apical plugs in simulated immature permanent teeth (an in vitro study).

BACKGROUND: This study aimed to compare the marginal adaptation of a single customized gutta percha cone with calcium silicate-based sealer versus mineral trioxide aggregate (MTA) and Biodentine apical plugs in simulated immature permanent teeth. METHODS: Thirty-nine extracted human maxillary anterior teeth were selected, prepared to simulate immature permanent teeth with an apical diameter 1.1 mm, placed in moist foam and divided into three groups. Group 1: Obturation with a single customized gutta percha cone and calcium silicate sealer. Group 2: MTA apical plug. Group 3: Biodentine apical plug. After incubation, teeth were horizontally sectioned at 1 mm and 3 mm from the apex and marginal adaptation was evaluated using scanning electron microscope (SEM). RESULTS: Biodentine showed the least mean gap size at both 1 and 3 mm from the apex with no statistically significant differences compared to MTA (p > 0.05). The single customized cone with calcium silicate based sealer showed the greatest mean gap size at both 1 and 3 mm from the apex with a statistically significant difference compared to the other groups (p < 0.001). CONCLUSION: Biodentine and MTA apical plugs provide a significantly better marginal adaptation to the dentinal walls than a single customized gutta percha cone with calcium silicate based sealer in simulated immature permanent teeth.

Influence of build direction, post-polymerization time, and aging on the fracture resistance and marginal and internal discrepancies of three-dimensional printed provisional crowns.

To evaluate the effect of build direction, post-polymerization time, and aging on the fracture resistance, failure mode, margin quality and Marginal (MD) and Internal Discrepancies (ID), and degree of conversion of tridimensional (3D) printed provisional crowns using the liquid crystal display technique (LCD). A left mandibular first molar was prepared and scanned. After, a full crown was designed (ExoCad) and exported to the LCD-printer software. One hundred and eighty crowns were printed at two build directions (30°, 90°) and post-polymerized for different periods (15, 30, 45 min). Half of the samples were aged (ST) in distilled water (37 °C/90 days). The marginal quality of the crowns was evaluated by the Schriwer method under a stereomicroscope (40x). The replica technique was used to measure the MD and ID and measured under a stereomicroscope (10x), through 20 reference points defined in 5 regions: Occlusal (O), Cusp (CP), Axial (AX), Chamfer (CH), and Finish Line (F). After, the crowns were cemented onto the respective dies using temporary cement and submitted to compression test (ISO150, 1 mm/min, 100 kgf).The failure mode was classified by Burke's fracture mode. The degree of conversion was evaluated through Fourier Transform Infrared Spectroscopy. The data (µm) of MD and ID and fracture resistance (N) were subjected to ANOVA (3 factors) and Tukey's test (5%); Weibull analysis was also performed for fracture resistance data (N). For MD, ID and fracture resistance ANOVA revealed that all factors (P < .001) were significant. For aged groups, the crowns printed at 30° showed lower MD (Tukey). The O_90_30 min (172.13A µm) and O_90_15 min (170.20A µm) groups showed the highest ID values. Higher resistance values were observed for the 30_45 min (844.30A N), 30_30 min (835.35A N), and 90_30 min (820.62A N) groups (Tukey). In the margin analysis, 98.6% of the crowns printed at 30° showed smooth margins without defects. The most prevalent fracture mode (41.7%) was Burke type 5. The degree of conversion (DC) increased with increasing post-polymerization time and aging. Printing provisional crowns at 30° provided lower crown MD and ID, as well as higher fracture resistance. A post-polymerization time of 30 min resulted in higher crown fracture resistance, while aging reduced the resistance of the crowns.

Marginal fit and retention force of zirconia resin-bonded fixed dental prostheses in the posterior region with different designs.

Background/purpose: Retainer debonding of resin-bonded fixed dental prostheses (RBFDPs) is one of the major reasons for their lower survival rates than fixed dental prostheses (FDPs) with full-coverage crowns. Recent advances in milling technology have enabled the fabrication of RBFDPs with complex retainers (D-shaped designs). This study aimed to assess the marginal fit and retention force of zirconia RBFDPs with inlay-, L-, and D-shaped designs to clarify their clinical applications. Materials and methods: Three abutment teeth models without maxillary second premolars were created using inlay-, L-, and D-shaped retainer designs. The zirconia RBFDPs were designed and fabricated according to the manufacturer's instructions (n = 10). The marginal gap was measured using the silicone replica technique. Zirconia frameworks were bonded to the abutment teeth using resin cement. Tensile test was conducted after thermal cycling and dynamic loading tests. The loads during debonding or fracture were recorded. The failure pattern was analyzed by observing the fracture surface using a scanning electron microscope. Results: D-shaped RBFDPs showed a significantly larger marginal gap than inlay- and L-shaped RBFDPs (P < 0.05). However, the mean marginal values were clinically acceptable (<120 µm). The D-shaped model exhibited the highest tensile strength in the tensile tests. The inlay-shaped and most of the D-shaped RBFDPs experienced debonding with cohesive failure, whereas the L-shaped RBFDPs showed fractures near the connector. Conclusion: The D-shaped retainer design was superior to the inlay- and L-shaped designs with respect to the inhibition of retainer debonding. However, the marginal fitness needs to be improved.

Effect of different fabrication workflows on the passive fit of screw-retained bar splinting two interforaminal implants: a parallel blinded randomised clinical trial.

BACKGROUND: To clinically compare the effect of the conventional and the digital workflows on the passive fit of a screw retained bar splinting two inter-foraminal implants. METHODS: The current study was designed to be a parallel triple blinded randomised clinical trial. Thirty six completely edentulous patients were selected and simply randomized into two groups; conventional group (CG) and digital group (DG). The participants, investigator and outcome assessor were blinded. In the group (CG), the bar was constructed following a conventional workflow in which an open top splinted impression and a lost wax casting technology were used. However, in group (DG), a digital workflow including a digital impression and a digital bar milling technology was adopted. Passive fit of each bar was then evaluated clinically by applying the screw resistance test using the "flag" technique in the passive and non passive situations. The screw resistance test parameter was also calculated. Unpaired t-test was used for intergroup comparison. P-value < 0.05 was the statistical significance level. The study protocol was reviewed by the Research Ethics Committee in the author's university (Rec IM051811). Registration of the clinical trial was made on clinical trials.gov ID NCT05770011. An informed consent was obtained from all participants. RESULTS: Non statistically significant difference was denoted between both groups in all situations. In the passive situation, the mean ± standard deviation values were 1789.8° ± 20.7 and1786.1° ± 30.7 for the groups (CG) and (DG) respectively. In the non passive situation, they were 1572.8° ± 54.2 and 1609.2° ± 96.9. Regarding the screw resistance test parameter, they were 217° ± 55.3 and 176° ± 98.8. CONCLUSION: Conventional and digital fabrication workflows had clinically comparable effect on the passive fit of screw retained bar attachments supported by two dental implants.

Influencia de los revestimientos dentales en la adaptación marginal e interna de las cofias metálicas. Estudio in vitro / Influence of dental investments on the marginal and internal adaptation of metal copings. In vitro study

Objetivo. Evaluar la influencia de diferentes marcas de revestimientos dentales en la adaptación marginal e interna de las cofias metálicas. Método. La investigación fue in vitro, analítico, experimental y transversal; para ello, se confeccionaron 48 cofias metálicas, las cuales fueron cementadas en dientes humanos previamente tallados, luego las cofias fueron cortadas mesio-distalmente para evaluar su adaptación. La adaptación fue evaluada usando un estereomicroscopio Leica DM6000M. Para determinar si hay diferencia en la adaptación marginal e interna se empleó el análisis de varianza, la prueba de comparación múltiple y la prueba de Duncan. Adicionalmente, la prueba de Fisher, se utilizó para evaluar la adaptación total. Resultados. La mejor adaptación marginal e interna de las cofias metálicas lo presenta el revestimiento Fórmula 1 (Whipmix), seguido del Castorit súper C (Dentaurum) y Bellasun (Bego). Conclusión. Los revestimientos dentales no mostraron influencia en la adaptación marginal; sin embargo, si mostraron influencia en la adaptación interna.

Objective. To evaluate the influence of different brands of dental investments on the marginal and internal adaptation of metal copings. Method. The research was in vitro, analytical, experimental and transversal. For this, 48 metal copings were made, which were cemented on previously carved human teeth, then the copings were cut mesio-distally to evaluate their adaptation. The adaptation was evaluated using a Leica DM6000M stereomicroscope. To determine if there is a difference between marginal and internal adaptation; the analysis of variance, the multiple comparison test and the Duncan test were used. Furthermore, Fisher's exact test was used to evaluate the total adaptation. Results. The best marginal and internal adaptation of metal copings is presented by the Formula 1 coating (Whipmix), followed by Castorit super C (Dentaurum) and Bellasun (Bego). Conclusion. Dental investments did not show influence on marginal adaptation; however, they did show influence on internal adaptation.

Clinical comparison of marginal fit of ceramic inlays between digital and conventional impressions.

PURPOSE: The aim of this stuldy was to compare the clinical marginal fit of CAD-CAM inlays obtained from intraoral digital impression or addition silicone impression techniques. MATERIALS AND METHODS: The study included 31 inlays for prosthodontics purposes of 31 patients: 15 based on intraoral digital impressions (DI group); and 16 based on a conventional impression technique (CI group). Inlays included occlusal and a non-occlusal surface. Inlays were milled in ceramic. The inlay-teeth interface was replicated by placing each inlay in its corresponding uncemented clinical preparation and taking interface impressions with silicone material from occlusal and free surfaces. Interface analysis was made using white light confocal microscopy (WLCM) (scanning area: 694 × 510 µm2) from the impression samples. The gap size and the inlay overextension were measured from the microscopy topographies. For analytical purposes (i.e., 95-%-confidence intervals calculations and P-value calculations), the procedure REGRESS in SUDAAN was used to account for clustering (i.e., multiple measurements). For p-value calculation, the log transformation of the dependent variables was used to normalize the distributions. RESULTS: Marginal fit values for occlusal and free surfaces were affected by the type of impression. There were no differences between surfaces (occlusal vs. free). Gap obtained for DI group was 164 ± 84 µm and that for CI group was 209 ± 104 µm, and there were statistical differences between them (p = .041). Mean overextension values were 60 ± 59 µm for DI group and 67 ± 73 µm for CI group, and there were no differences between then (p = .553). CONCLUSION: Digital impression achieved inlays with higher clinical marginal fit and performed better than the conventional silicone materials.

Hot isostatic pressing as an alternative thermo-mechanical treatment for metallic full-arch implant-supported frameworks obtained by additive and subtractive manufacturing technology: Vertical and horizontal fit, screw removal torque, and stress analysis.

PURPOSE: To assess vertical and horizontal fit, screw removal torque, and stress analysis (considered biomechanical aspects) of full-arch implant frameworks manufactured in Ti-6Al-4V through milling, and additive manufacturing Direct Metal Laser Sintering (DMLS) and Electron Beam Melting (EBM), and the effect of the thermo-mechanical treatment Hot Isostatic Pressing (HIP) as a post-treatment after manufacturing. MATERIAL AND METHODS: Maxillary full-arch implant frameworks were made by milling, DMLS, and EBM. The biomechanical assessments were screw removal torque, strain-gauge analyses, and vertical and horizontal marginal fits. The vertical fit was assessed by the single-screw test and with all screws tightened. All frameworks were submitted to a standardized HIP cycle (920°C, 1000 bar pressure, 2 h), and the tests were repeated (α = 0.05). RESULTS: At the initial time, milled frameworks presented higher screw removal torque values, and DMLS and EBM frameworks presented lower levels of strain. Using the single-screw test, milled and DMLS frameworks presented higher vertical fit values, and with all screws tightened and horizontally, higher fit values were found for milled frameworks, followed by DMLS and EBM. After HIP, milling and EBM frameworks presented higher screw removal torque values; the lowest strain values were found for EBM. Using the single-screw test, milled and DMLS frameworks presented higher vertical fit values, and with all screws tightened and horizontally no differences were found. CONCLUSIONS: DMLS and EBM full-arch frameworks presented adequate values of screw removal torque, strain, and marginal fit, although the worst values of marginal fit were found for EBM frameworks. The HIP cycle enhanced the screw removal torque of milled and EBM frameworks and reduced the strain values of milled frameworks. The HIP represents a reliable post-treatment for Ti-6Al-4V dental prostheses produced by milling and EBM technologies.

Influence of polyether ether ketone coping crown on the adaptation of implant abutment.

OBJECTIVE: To evaluate the influence of polyether ether ketone coping crown on the adaptation of implant abutment. Methods: The vitro study was conducted at the department of Prosthodontics, Hainan Stomatological Hospital, China, from October 2021 to March 2022, and comprised patients undergoing implant surgery on first molar. Patients were divided into two groups, with group A patients receiving polyether ether ketone coping crowns, and group B receiving zirconia crowns. Replica technique was used to replicate the gap between the crowns and the abutments. The thickness of the silicone film was measured under the stereomicroscope, and the gap between the groups was compared. Data was analysed using SPSS 22. RESULTS: In group A, mean marginal gap was 82.43±25.00µm, and mean overall gap was 85.45±33.75µm. In group B, the corresponding values were 65.09±11.69µm and 78.04±26.67µm. There was a significant difference in the adaptation between the groups at the marginal and overall measurement points (p<0.05). Conclusion: Marginal and internal adaptations of polyether ether ketone coping crown for abutment could be considered clinically acceptable.

Build angle effect on 3D-printed dental crowns marginal fit using digital light-processing and stereo-lithography technology: an in vitro study.

BACKGROUND: The effect of 3D printing technology and build angle on the marginal fit of printed crowns is unclear. The objective of this research was to use digital light processing (DLP) and stereo-lithography (SLA)-based 3D printing to construct single restorations with varied build angles and to analyze the crowns' marginal fit. METHODS: A prepared resin first molar was scanned utilizing an optical scanner. Three build orientations were used to construct the specimens: 0, 45, and 90º. DLP and SLA technology were used to produce the casting patterns. A digital microscope was used to measure the marginal gaps. The effect of build orientation was statistically analyzed by using Two-way ANOVA followed by pair-wise Tukey test. RESULTS: Two-way ANOVA revealed a significant effect of printer technology and build angle on the marginal discrepancy of 3D printed crowns (p < 0.001). One-way ANOVA revealed that SLA printers (55.6 [± 13.59]) showed significantly better mean [± SD] marginal discrepancy in µm than DLP printers (72 [± 13.67]) (p < 0.001). Regarding build angle, one-way ANOVA revealed significant differences between the different angles. Tukeys post-hoc test revealed that 0° (48.5 [± 9.04]) had the significantly smallest marginal discrepancy followed by 45° (62.5 [± 8.05]) then 90° (80.5 [± 8.99]) (p < 0.001). CONCLUSION: The build orientation affects the marginal discrepancy of single crowns manufactured utilizing DLP and SLA.

Influence of fabrication method on the marginal fit of temporary restorations

Abstract Computer-aided manufacturing (CAM) technology allows the use of different manufacturing techniques. This in vitro study aimed to evaluate the marginal fit of temporary restorations manufactured using conventional chairside methods, milling, and three-dimensional printing. Fifteen 3-element temporary restorations specimens were produced and categorized into three groups: non-digital, obtained using the conventional chairside method (GC); milled (GM); and three-dimensionally printed (GP). Marginal fit was assessed using scanning electron microscopy (SEM) performed under two conditions: one with only the central screw tightened, and the other with all three screws tightened. Horizontal misfit values were categorized as over-, equal-, and under-extended and qualitatively analyzed. Statistical analysis was performed using the Tukey-Kramer test (α=0.05). In the vertical assessment, three-dimensionally printed restorations demonstrated greater misfit than restorations obtained by milling and the conventional chairside method (P<0.05). In the horizontal assessment, the misfit in the GP group was significantly higher than that in the GM and GC groups. Restorations obtained using the conventional chairside method and milled provisional restorations showed more favorable results than three-dimensionally printed restorations.

THE MARGINAL ACCURACY OF LITHIUM DISILICATE SINGLE CROWNS IS COMPAREABLE WHEN MADE FROM CONVENTIONAL OR DIGITAL (DIRECT OR INDIRECT) WORKFLOWS.

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: Tabesh M, Nejatidanesh F, Savabi G, Davoudi A, Savabi O. Marginal accuracy of lithium disilicate full coverage crowns made by direct and indirect digital or conventional workflows: a systematic review and meta-analysis. J Prosthodont. 2022;31(9):744-753. doi:10.1111/jopr.13515. SOURCE OF FUNDING: Dental Research Center, Isfahan University of Medical Sciences Research Grant #298095. TYPE OF STUDY/DESIGN: Systematic review with meta-analysis of data.

Comparison of marginal and internal adaptation of provisional polymethyl methacrylate restorations fabricated by two three-dimensional printers: An in vitro study.

Background: Chairside fabrication of provisional restorations using three-dimensional (3D) printers is rising in digital dentistry. The purpose of this research was to compare the marginal and internal adaptation of provisional polymethyl methacrylate (PMMA) restorations fabricated by two different 3D printers. Materials and Methods: In this in vitro investigation, an intact maxillary 1st molar acrylic model was first digitalized by a laboratory scanner. It was then prepared for an all-ceramic restoration and scanned again by the same scanner. The final restoration was designed in Exocad according to the scan files with a 50 µm cement gap. PMMA restorations were printed by two 3D printers; Group 1: Asiga (n = 10) and Group 2: Digident (n = 10). The replica technique was used to assess the marginal and internal fit of the restorations, and one-way ANOVA was used to analyze the data. P <0.05 was regarded as statistically significant. Results: The mean marginal gap of crowns in Group 1 was significantly lower than that of Group 2 (75 vs. 195 µm, P = 0.001). Regarding internal adaptation, no significant difference was found between the axial gap values in both groups (P > 0.05). The mean occluso-axial gap (90 vs. 140 µm, P = 0.026) and the mean occlusal gap (116 vs. 300 µm, P = 0.001) of crowns in Group 1 were significantly smaller compared to the equivalent values in Group 2. Conclusion: Provisional PMMA crowns fabricated by the Asiga printer showed significantly higher marginal and internal adaptation than those manufactured by Digident at all points except for the axial surface.

Effect of blood contamination on marginal adaptation of cold ceramic and MTA angelus: a scanning electron microscopic study.

BACKGROUND: This study aimed to assess the effect of blood contamination on marginal adaptation of cold ceramic (CC) and mineral trioxide aggregate (MTA) Angelus using scanning electron microscopy (SEM). METHODS: This in vitro experimental study was conducted on 24 extracted single-rooted human teeth. After cleaning and shaping, the root canals were filled with lateral compaction technique. The apical 3 mm of the roots was cut, and cavities with 3 mm depth were created at the apex. The teeth were randomly assigned to two group (n = 12) for the application of CC and MTA Angelus as retrograde filling materials. CC and MTA Angelus were prepared by mixing the powder with blood, and applied in the cavities. After 24 h, their marginal adaptation to the canal walls was assessed by SEM. Data were statistically analyzed by t-test (alpha = 0.05). RESULTS: The mean marginal gap was 8.98 µm in the CC, and 16.26 µm in the MTA Angelus group; this difference was statistically significant (P < 0.001). CONCLUSIONS: The present in vitro study revealed that following complete blood contamination of powder, CC showed significantly superior marginal adaptation than MTA Angelus as shown by SEM assessment.

Adaptación marginal e interna de cofias fabricadas por métodos convencionales, CAD/CAM de fresado y sinterizado por láser / Marginal and internal adaptation of copings manufactured by conventional methods, CAD/CAM milling and laser sintering

Introducción: la adaptación marginal e interna de nuestras restauraciones fabricadas por fundición sistemas de fresado y sinterización láser es uno de los factores clínicos más importantes para el éxito de las prótesis fijas, previniendo el riesgo de microfiltración y enfermedad periodontal. Objetivo: evaluar la adaptación marginal e interna de cofias metálicas en aleación Cr-Co confeccionadas por técnicas convencionales, CAD/ CAM de fresado y sinterizado por láser. Material y métodos: estudio de tipo experimental, comparativo e in vitro. Se imprimió un modelo maestro en Cr-Co, proveniente del escaneo de un premolar preparado para corona completa, sobre el cual se diseñaron 30 cofias divididas en tres grupos: el primero que corresponde al grupo cofias fundidas fresadas en disco de cera A (A = 10), el segundo grupo cofias fresadas en disco de metal presinterizado B (B = 10) y el tercer grupo cofias impresas por sinterización láser C (C = 10). Se empleó la réplica de silicona, colocando silicona al interior de cada cofia, sobre el modelo maestro, simulando al cemento, mediante una máquina de ensayo universal se realizó una compresión de 50 N. Luego de retirar cada cofia se rellenaron con silicona pesada de adición, obteniendo una réplica de silicona. Se efectuaron dos cortes transversales en sentido vestíbulolingual y mesiodistal. Se observó el espesor de silicona VPS (vinil poliéter silicona) mediante un estereomicroscopio (Nikon SMZ745T), obteniendo valores en micrómetros. Para el análisis estadístico se utilizó el software SPSS 25 con el fin de realizar la prueba de normalidad y ANOVA de dos vías bajo un nivel de confianza del 95%. Resultados: el menor gap lo obtuvo el grupo de fresadas, seguido de las impresas y por último las fundidas por métodos convencionales. ANOVA de dos vías reveló diferencias estadísticamente significativas entre los tres grupos (p < 0.0001). Conclusiones: se encontró que el gap varía con cada método de fabricación, la técnica convencional de fundido mostró un mayor gap, ninguna excediendo el rango clínicamente aceptable (AU)

Introduction: the marginal and internal adaptation of our restorations manufactured by casting, milling systems and laser sintering is one of the most important clinical factors for the success of fixed prostheses, preventing the risk of microleakage and periodontal disease. Objective: evaluate the marginal and internal adaptation of metal copings in Cr-Co alloy made by conventional techniques, CAD/CAM milling and laser sintering. Material and methods: an experimental, comparative and in vitro study, a Cr-Co master model was printed from the scan of a premolar prepared for a full crown. An experimental, comparative and in vitro study, a Cr-Co master model was printed from the scan of a premolar prepared for a full crown, on which 30 caps divided into three groups were designed; the first group corresponds to the cast copings milled on a wax disc A (A = 10), the second group milled copings on a presintered metal disc B (B = 10) and the third group printed by laser sintering copings C (C = 10). The silicone replica was used, placing silicone inside each coping, on the master model, simulating cement, using a universal testing machine, a 50 N compression was performed. After removing each coping, they were filled with heavy addition silicone, obtaining a silicone replica. Two cross-sections were made in the buccolingual and mesiodistal direction., observing the thickness of the VPS (vinyl polyeter silicone) silicone using a stereomicroscope (Nikon SMZ745T), obtaining values in micrometers. For the statistical analysis, the SPSS 25 software was used in order to perform the normality and two-way ANOVA tests under a 95% confidence level. Results: the smallest gap was obtained by the milled group, followed by the printed ones and finally those cast by conventional methods. Two-way ANOVA revealed statistically significant differences between the three groups (p < 0.0001). Conclusions: the gap was found to vary with each fabrication method, the conventional casting technique showed a larger gap, none exceeding the clinically acceptable range (AU)

Marginal fit of endocrowns fabricated by three-dimensional printing and the conventional method: An in vitro study.

Background: Marginal fit is a key factor in success of prosthetic restorations. This study aimed to assess and compare the marginal fit of endocrowns fabricated by three-dimensional (3D) printing and the conventional method. Materials and Methods: This in vitro, experimental study evaluated 20 endocrowns, of which 10 were fabricated by 3D printing and 10 were fabricated by the conventional wax-up technique. The marginal gap was measured at 8 points under a stereomicroscope. The results were analyzed using the Shapiro-Wilk test, paired t-test, independent t-test, and one-way analysis of variance (α = 0.05). Results: The mean marginal gap was maximum at the distal point, and minimum at the buccal point for the conventionally fabricated endocrowns with an overall mean marginal gap of 99.67 ± 4.59 µm. The mean marginal gap was maximum at the mesiobuccal and minimum at the buccal point before pressing (overall mean of 103.92 ± 2.19 µm) before pressing, and maximum at the distobuccal and minimum at the mesiobuccal point after pressing (overall mean of 117.67 ± 2.87 µm). According to paired t-test, the mean marginal gap of endocrowns fabricated by 3D printing significantly increased after pressing at all 8 points and also in general, compared with before pressing (P < 0.001). Furthermore, the mean marginal gap at all points was significantly greater in endocrowns fabricated by 3D printing compared with those fabricated by the conventional method (independent t-test, P < 0.001). Conclusion: Within the limitations of this in vitro study, the results showed that endocrowns fabricated by the conventional method had significantly superior marginal fit than those fabricated by 3D printing.

Comparing the accuracy of distinct scanning systems and their impact on marginal/internal adaptation of tooth-supported indirect restorations. A scoping review.

OBJECTIVE: To summarize the existing scientific evidence on the effect of distinct intraoral (IOS) and extraoral (EOS) scanners in terms of their accuracy for image acquisition and the marginal/internal adaptation of indirect restorations. METHODS: The protocol of this scoping review is available online (https://osf.io/cwua7/). A structured search, with no date restriction, was performed in LILACS, MEDLINE via Pubmed, EMBASE, Web of Science, and Scopus, for articles written in English. The inclusion criteria were studies that considered at least two scanners, regardless of method (intra or extraoral), for the production of tooth-supported restorations. Two independent and blinded researchers screened the studies, collected and analyzed the data descriptively. RESULTS: 103 studies were included (55 on marginal/internal adaptation, 33 on accuracy, 5 on both outcomes, and 10 reviews). Most of them, shown clinically acceptable adaptation (<120 µm). Factors commonly related to the performance of scanners are: use of anti-reflection powders, method of image acquisition, and restoration/tooth characteristics. The need of anti-reflection powders was controversial. Different scanning principles seems to result on similar performance; IOS that combine them could be promising. The most explored systems were Omnicam - IOS, and inEos X5 - EOS, which showed similar performance on marginal/internal adaptation. Scarce studies explored the performance of EOS systems, especially in terms of accuracy. Different restoration designs as single-unit seemed not to modify the performance of scanners. Limited information is available regarding the planned cement space, restorative material and design (multi-unit restorations), as also techniques to measure adaptation. CONCLUSIONS: Digital scanners are valid approaches to obtain accurate impressions resulting in clinically acceptable restorations. Systems that uses combined principles of image acquisition seems promising for optimal performance. Based on high discrepancy, the quality of evaluated evidence is low, and well-designed studies are still encouraged, especially considering validated IOS/EOS as a control comparison condition.

Comparison of marginal accuracy in two different materials used in provisional crown and bridge - an in vitro experimental study.

OBJECTIVE: To determine the difference in the marginal accuracy at buccal, lingual, mesial and distal margins of temporary crowns fabricated with bisacryl-based temporary crown material. METHODS: The in-vitro, experimental, laboratory-based study was conducted at the Aga Khan University, Karachi, from September to December 2019, and comprised two bisacryl-based temporary crown material, Integrity and Protemp 4, which were used to fabricate a sample of 24 temporary crowns. A pre-operative polyvinyl siloxane impression served as a template for temporary crown fabrication. A right mandibular molar tooth on a typodont was prepared to receive a crown. The provisional crown material was syringed onto the template and was allowed to cure. All four surfaces of the crown were observed under a stereomicroscope equipped with digital single-lens reflex camera at 25.6x magnification. An image of each surface was captured and a photographic record was maintained. An image processing software was used for the measurement of marginal discrepancy. Marginal accuracy among the four surfaces was assessed. Data was analysed using SPSS 23. RESULTS: Mean marginal discrepancy for provisional crowns fabricated with Protemp 4 and Integrity was 410±222µm and 319±176µm, respectively. The marginal discrepancy between the two groups was statistically significant (p=0.027), with buccal margin exhibiting the most discrepancy (p<0.01). CONCLUSIONS: Integrity showed less microleakage than Protemp 4. Among all the walls, the buccal wall showed the most microleakage. Marginal accuracy was found to be dependent upon the type of provisional crown material and the side of the prepared axial wall.

The effect of preparation design on the fracture resistance and adaptation of the CEREC ceramic endocrowns.

OBJECTIVE: The purpose of this experimental in vitro study was to assess the effect of having one or two intact axial walls on the improvement of the fracture resistance, and marginal and internal adaptation of computer-aided design/computer-aided manufacturer fabricated ceramic endocrowns. MATERIALS AND METHODS: Thirty-six endodontically treated mandibular molars were divided into three groups (n = 12). Group A, represented teeth that all of their axial walls were reduced till they all had 3 mm height. In group B, the buccal wall had 5 mm height and the others were reduced to 3 mm. Specimens of the group C had 5-mm-height buccal and one 5 mm-height proximal wall, with all other walls of 3 mm height. All teeth were scanned using intraoral scanner, and endocrowns were milled from zirconia lithium silicate ceramics blocks. The marginal and internal discrepancy of restorations were evaluated with the replica technique. Fracture resistance was also measured after cementation and modes of failure were observed. One-way analysis of variance and Tukey HSD multiple comparisons were used to analyze the data (α = .5). RESULTS: Significant differences were observed within the groups in terms of the axial discrepancy (p = .022); group A had significantly higher amounts of axial discrepancy compared to group B (p = .001) and group C (p = .003). Preservation of the intact axial walls did not result in a statistically significant decrease in marginal (p = .21) and pulpal (p = .31) discrepancy values. Also, concerning the fracture resistance no significant difference was observed among the groups (p = .51). CONCLUSION: Preservation of at least one of the axial walls could reduce the amount of the axial discrepancy and, therefore, improves the adaptation of the restoration. However, based on this study, it did not improve fracture resistance.

Assessment of Marginal and Internal Adaptation in Provisional Crowns Utilizing Three Distinct Materials.

AIMS: This study aimed to assess the marginal and internal adaptation of provisional crowns fabricated from polymethyl methacrylate (PMMA) blocks by the computer-aided design/computer-aided manufacturing (CAD/CAM) system, autopolymerizing PMMA, and acrylic base composite resin. MATERIALS AND METHODS: In this in vitro experimental study, a brass die was obtained, and provisional crowns were fabricated in three groups using Teliocad PMMA blocks by the CAD/CAM system, Tempron GC auto-polymerizing PMMA, and Bisico acrylic base composite resin (n = 7 in each group). The provisional crowns were coded and randomly placed on the die. Their marginal adaptation was evaluated under a stereomicroscope at 40× magnification, while their internal adaptation was assessed by the replica technique. Data were analyzed by one-way analysis of variance (ANOVA) (α = 0.05). RESULTS: The mean marginal gap was the highest in autopolymerizing PMMA and the lowest in the CAD/CAM PMMA group (p < 0.05). The mean marginal gap in the autopolymerizing PMMA group was significantly higher than that in the resin material (p = 0.014) and CAD/CAM PMMA (p = 0.000) groups. The difference between the resin material and CAD/CAM PMMA groups was not significant (p = 0.13). The mean internal gap was the highest in autopolymerizing PMMA group and the lowest in CAD/CAM PMMA group (p < 0.05). The mean internal gap in autopolymerizing PMMA group was significantly higher than that in composite resin (p = 0.002) and CAD/CAM PMMA (p = 0.00) groups. The difference between the resin material and CAD/CAM PMMA groups was not significant (p = 0.322). CONCLUSION: Computer-aided design/Computer-aided manufacturing PMMA provisional crowns showed the highest marginal and internal adaptation followed by acrylic base resin material crowns. CLINICAL SIGNIFICANCE: Computer-aided design/computer-aided manufacturing PMMA crowns demonstrate superior marginal and internal adaptation compared with autopolymerizing PMMA and acrylic base composite resin crowns, suggesting CAD/CAM technology's potential for enhancing clinical outcomes. How to cite this article: Jalalian E, Younesi F, Golalipour S, et al. Assessment of Marginal and Internal Adaptation in Provisional Crowns Utilizing Three Distinct Materials. J Contemp Dent Pract 2023;24(11):853-858.

The Effect of Immediate Dentin Sealing on the Marginal Adaptation of LithiumDisilicate Overlay Restorations using different types of luting agents / Efeito do selamento imediato da dentina na adaptação marginal de restaurações overlay de dissilicato de lítio utilizando diferentes tipos de agentes de cimentação: estudo in vitro

Objective:This study evaluated the effect of immediate dentin sealing on the marginal adaptation of lithium disilicate overlays with three different types of resin-luting agents: preheated composite, dual-cure adhesive resin, and flowable composite. Materials and Methods: Forty-eight maxillary first premolars of similar size were prepared with a butt joint preparation design. The teeth were separated into two primary groups, each with twenty-four teeth: Group DDS: Delay dentin sealing (non-IDS) teeth were not treated. Group IDS: dentin sealing was applied immediately after teeth preparation. Each group was subsequently separated into three separate subgroups. Subgroups (DDS+Phc, IDS+Phc): cemented with preheated composite (Enamel plus HRi, Micerium, Italy), Subgroups (DDS+Dcrs, IDS+Dcrs): cemented with dual-cured resin cement (RelyX Ultimate, 3M ESPE, Germany) and Subgroups (DDS+Fc, IDS+Fc): Cemented with flowable composite (Filtek supreme flowable, 3M ESPE, USA). Using a digital microscope with a magnification of 230x, the marginal gap was measured before and after cementation at four different locations from each surface of the tooth, and the mean of measurements was calculated and analyzed statistically using the independent t-test, one-way ANOVA test, Bonferroni correction at a significance level of 0.05. Results: The samples that were immediately sealed with dentin bonding agent showed lower marginal gaps than delayed dentin sealing, both pre-and post-cementation for all subgroups, with a statistically significant difference (p˂0.01). The marginal gap was significantly lower in the IDS+Fc (48.888 ±5.5 µm) followed by the IDS+Dcrs group (53.612 ±5.8 µm) and IDS+Phc (79.19 9±6.9 µm) respectively, while the largest marginal gaps were observed in the DDS+Phc group (86.505 ±5.4 µm). Conclusion: Generally, the teeth with IDS showed better marginal adaptation than teeth without IDS. The marginal gap was smaller with flowable composite and dual-cure resin cement than with preheated composite (AU)

Objetivo:Esse estudo avaliou o efeito do selamento imediato da dentina na adaptação marginal de overlays em dissilicato de lítio com três tipos diferentes de agentes de cimentação resinosos: resina composta pré-aquecida, adesivo resinoso dual e resina fluida. Materiais e métodos: Quarenta e oito primeiros pré-molares maxilares com tamanho similar foram preparados com término em ombro. O dente foi separado em dois grupos primários, cada um com vinte e quatro dentes: Grupo DDS: retardado selamento da dentina (non-IDS) dente não foi tratado. Grupo IDS: selamento dentinário foi aplicado imediatamente após a preparação do dente. Cada grupo foi separado de modo subsequente em três subgrupos. Subgrupo (DDS+Phc, IDS+Phc): cimentado com resina pré-aquecida (Enamel plus HRi, Micerium, Italy), Subgrupo (DDS+Dcrs, IDS+Dcrs): cimentado com cimento resinoso dual (RelyX Ultimate, 3M ESPE, Germany) e Subgrupo (DDS+Fc, IDS+Fc): cimentado com resina fluida (Filtek supreme flowable, 3M ESPE, USA). Usando um microscópio digital com magnificação de 230x, o gap marginal foi medido antes e após a cimentação em quatro diferentes localizações de cada superfície do dente e a média das medidas foi calculada e estatisticamente analisada através do uso do teste ANOVA um-fator e teste independente de Tukey e correção Bonferroni com nível de significância de 0,05. Resultado: As amostras que foram imediatamente seladas com agente adesivo dentinário apresentaram menores gaps marginais do que o selamento dentinário retardado, ambos pré e pós cimentação para todos os subgrupos apresentaram diferença estatística significante (p˂0.01). O gap marginal foi significativamente menor para IDS+Fc (48.888 ±5.5 µm) acompanhado do IDS+Dcrs group (53.612 ±5.8 µm) e IDS+Phc (79.19 9 ±6.9 µm) respectividamente, enquanto o maior gap marginal foi observado no grupo DDS+Phc (86.505 ±5.4 µm). Conclusão:Geralmente, o dente com IDS apresentou melhor adaptação marginal do que o dente sem IDS. O gap marginal foi menor com resina fluida e cimento resinoso dual do que com a resina composta pré-aquecida (AU)