From Mindless Mechanic to Educated Educator.

Over the last 100 years, the dental profession has undergone incredible progress to address problems created by oral disease. Our ability to restore function and esthetics efficiently and predictably via modern restorative materials, regenerative treatments, dental implant therapy, and digitally driven workflows is truly remarkable. For those members of our profession privileged to work in fully developed economies, the prevailing perception is that the war against caries, periodontitis, and edentulism has been largely won. There has surely never been a more exciting time to be in dentistry. Thus, it may sound paradoxical or even alarmist to state that dentistry is falling behind in its mission to serve the needs of our patients­but it is.^ieng

Translucency of chairside monolithic zirconias using different sintering ovens: An in vitro investigation.

OBJECTIVE: To evaluate the translucency of several monolithic zirconias (MZ) processed in various sintering ovens designed for single-visit, chairside use. METHODS: Discs (n = 40) from zirconia blocks were fabricated for each MZ at manufacturer-recommended minimal thicknesses, as provided in each material's instructions for use: IPS e.max ZirCAD LT (ZLT); CEREC Zirconia+ (CZ+); 3M Chairside (3M); KATANA Zirconia (KT). Groups (n = 10) were sintered following manufacturer instructions for each oven: CEREC SpeedFire, Ivoclar CS4, Ivoclar CS6, and Ivoclar S2 (laboratory furnace control). Specimens were highly polished on one side and glazed on the other. Each side was measured with a spectrophotometer against white and black backgrounds to determine translucency parameter (TP) and contrast ratio (CR) values. Results for TP and CR for each material and oven combination were compared with a linear mixed model. Oven precision was evaluated using the Kruskall-Wallis test. RESULTS: Glazed specimens were more translucent than polished ones (p < 0.001). ZLT and CZ+ were more translucent than 3M and KT regardless of the sintering oven (p < 0.01). Several oven/material combinations reached or exceeded the S2 oven TP: CS4 with CZ+ and 3M; CS6 with ZLT and KT (p < 0.01). SpeedFire was significantly less precise (p < 0.05) and produced lower TP values for ZLT, CZ+, and KT (p < 0.01). Results for TP and CR were highly correlated. CONCLUSIONS: MZ surface finish, material thickness, and oven used all had a significant effect on translucency. Some chairside-oriented solutions produced results with translucency equal to conventionally processed zirconia. CLINICAL SIGNIFICANCE: The translucency of a ceramic restoration is an important factor in determining its esthetics. Clinicians desiring the most esthetic outcomes with monolithic zirconia should be aware of the significant effects that surface finishing, material thickness, and the sintering oven used can have on restoration translucency.

Trueness and precision of complete arch dentate digital models produced by intraoral and desktop scanners: An ex-vivo study.

OBJECTIVES: The study aimed to compare the trueness and precision of five intraoral scanners (Emerald S, iTero Element 5D, Medit i700, Primescan, and Trios 4) and two indirect digitization techniques for both teeth and soft tissues on fresh mandibular and maxillary cadaver jaws. METHODS: The maxilla and mandible of a fully dentate cadaver were scanned by the ATOS industrial scanner to create a master model. Then, the specimens were scanned eight times by each intraoral scanner (IOS). In addition, 8 polyvinylsiloxane (PVS) impressions were made and digitized with a Medit T710 desktop scanner. Stone models were then poured and again scanned with the desktop scanner. All IOS, PVS, and stone models were compared to the master model to calculate the mean absolute surface deviation for mandibular teeth, maxillary teeth, and palate. RESULTS: For mandibular teeth, the PVS trueness was only significantly better than the Medit i700 (p < 0.001) and Primescan (p < 0.05). In maxillary teeth, the PVS trueness was significantly better than all IOSs (p < 0.05-0.001); the stone trueness was significantly better than Emerald S (p < 0.01), Medit i700 (p < 0.001) and Primescan (p < 0.01). In the palate, PVS and stone trueness were significantly lower than the iTero Element 5D (p < 0.01) and Trios 4 (p < p < 0.01). Stone trueness was significantly lower than the Medit i700 (p < 0.05). The precision in the palate was significantly lower for PVS and stone than for Emerald S (p < 0.01, p < 0.05), iTero Element 5D (p < 0.01, p < 0.01), Primescan (p < 0.001, p < 0.001), and Trios 4 (p < 0.001, p < 0.01). Significant differences in trueness between the IOSs were observed only in the mandibular teeth. The Medit i700 performed worse than Emerald S (p < 0.01) and iTero Element 5D (p < 0.01). For mandibular teeth, the Medit i700 was significantly more precise than Primescan (p < 0.01) and the Emerald S (p < 0.05). The Trios 4 was significantly less precise than Emerald S (p < 0.05). The precision of Medit i700 was significantly worse than iTero Element 5D (p < 0.01) for maxillary teeth, as well as the Primescan (p < 0.01) and Trios 4 (p < 0.05) for the palate. CONCLUSIONS: In general, indirectly digitized models from PVS impressions had higher trueness than IOS for maxillary teeth; precision between the two methods was similar. IOS was more accurate for palatal tissues. The differences in trueness and precision for mandibular teeth between the various techniques were negligible. CLINICAL SIGNIFICANCE: All investigated IOSs and indirect digitization could be used for complete arch scanning in mandibular and maxillary dentate arches. However, direct optical digitization is preferable for the palate due to the low accuracy of physical impression techniques for soft tissues.

Differences in Volumetric Tooth Loss for Monolithic Ceramic Crowns, Occlusal Overlays and Partial Coverage Onlays.

PURPOSE: The purpose of this in vitro study was to compare the volumetric loss of clinical crown structure for commonly encountered clinical situations for monolithic ceramic crowns, occlusal overlays, and partial coverage onlays. MATERIALS AND METHODS: Typodont teeth made with pre-existing mesio-occluso-distal (MOD) preparations for mandibular first molars and maxillary first premolars were prepared with three different preparations: a full contour monolithic zirconia crown, a lithium disilicate occlusal overlay, and mesio-occluso-disto-buccal/mesio-occluso-disto-lingual (MODB/MODL) lithium disilicate onlays for premolars/molars. 3D metrological software was used to evaluate the volumetric loss of clinical crown structure for each preparation type. Subsequently, the mesiolingual cusps of mandibular molars and buccal cusps of maxillary premolars were excluded for a separate analysis, to simulate patient presentation with an existing restoration and sheared off cusp. RESULTS: Full coverage monolithic zirconia crowns removed 45.37 - 219.53 mm3 of remaining clinical tooth structure, depending on the clinical scenario and tooth position, while lithium disilicate overlays removed 27.48 - 105.13 mm3. MODB/MODL lithium disilicate onlays removed 5.48 - 47.45 mm3 . In each scenario tested, MODB/MODL onlays removed significantly less clinical crown structure than overlays (P<0.001); both MODB/MODL onlays and overlays removed significantly less structure than full coverage crowns (P<0.001). CONCLUSION: Monolithic zirconia crown restorations require significantly more removal of remaining tooth structure than lithium disilicate occlusal overlays and partial coverage onlays for commonly occurring clinical situations requiring indirect restorations. Int J Prosthodont 2023. doi: 10.11607/ijp.8011.

Comparison of marginal and internal fit of pressed lithium disilicate veneers fabricated via a manual waxing technique versus a 3D printed technique.

OBJECTIVE: The purpose of this in vitro study was to compare the marginal and internal fit of pressed lithium disilicate veneers fabricated from a 3D printed castable wax resin versus a manual waxing technique. MATERIALS AND METHODS: A typodont model central incisor was prepared for a porcelain veneer. Following stone model fabrication from a polyvinyl siloxane impression, the model was digitized using a laboratory scanner. Group 1 veneers were designed digitally and 3D printed with a castable wax resin, then pressed. Group 2 veneers were fabricated using a manual wax and press approach. Veneers from both groups were bonded to printed dies. Following measurements of marginal adaptation under a stereo microscope, the dies were sectioned and measurements were made for internal adaption. Statistical analysis included a Kolmogorov test and a Mann-Whitney U test. RESULTS: Average marginal gap (µm) for Group 1 was 40.37 ± 11.75 and 50.63 ± 16.99 for Group 2 (p = 0.51). Average internal gap (µm) for Group 1 was 61.21 ± 18.20 and 68.03 ± 14.07 for Group 2 (p = 0.178). CONCLUSION: There was no difference in marginal fit or internal fit between pressed lithium disilicate veneers fabricated with a 3D printed castable resin and those fabricated with a manual waxing technique. The use of digital technologies and 3D printing provide significant advantages in the fabrication of pressed glass ceramic veneers, with marginal and internal adaptation comparable to manual wax and press techniques.

Impression-Making in 2020: How Long Before Analog Methods Are Obsolete?

Impression-making is a necessary part of providing restorative and rehabilitative dentistry to patients. The use of physical impression trays and materials dates back to at least the 19th century, which included the development of corrective and functional impression techniques.1 This method of acquiring and conveying information remained largely unchanged throughout the 20th century, although the development and subsequent improvement of elastomeric impression materials greatly enhanced the quality and predictability of impression results. Now with the digitization of the dental profession, the introduction and advancement of digital impressions represents the latest step forward in impression-making. This article reviews the current state of physical impression-making and the.

Adhesive Dentistry: Changing Restorative Treatment for the Better.

Amalgam fillings and full-coverage gold crowns have long been the "gold standard" for direct and indirect restorations of cariously involved and/or broken teeth. While these restorations have a proven track record for functional success, they are not ideal with respect to esthetic outcomes or the preservation of residual tooth structure for subsequent solutions upon failure. The development of modern, adhesively retained restorations has enabled clinicians to provide patients a long-lasting solution that is not only a more conservative option for addressing diseased and/or structurally damaged teeth, but a more esthetic one. This article will review recent developments in adhesive dentistry, as well as the often-overlooked excellent track record already established by direct resin and indirect all-ceramic restorations.

Immediate shear bond strength of resin cements to sodium hypochlorite-treated dentin.

INTRODUCTION: The purpose of this in vitro study was to evaluate the immediate shear bond strength of different categories of resin cements on sodium hypochlorite (NaOCl)-treated dentin and to evaluate if the bond was improved by a subsequent treatment with 10% sodium ascorbate before adhesive procedures. METHODS: This study tested immediate shear bond strengths to human dentin of 5 resin cements: Variolink II (Ivoclar Vivadent, Schaan, Liechtenstein), Multilink (Ivoclar Vivadent), Clearfil Esthetic Cement EX (Kuraray, Tokyo, Japan), SpeedCEM (Ivoclar Vivadent), and Clearfil SA Cement (Kuraray). All cements were tested with no NaOCl pretreatment of the dentin (negative control) and with a 20-minute exposure of the dentin to 6% NaOCl before bonding procedures. The cements found to have decreased bond strengths to NaOCl-treated dentin were tested with the dentin exposed to 10% sodium ascorbate after NaOCl exposure. The sodium ascorbate exposure times tested were 5 seconds and 1 minute. RESULTS: The mean and standard deviation values for immediate shear bond strength (MPa) for the negative control group were as follows: Variolink II, 18.8 ± 4.2; Multilink, 29.1 ± 7.1; Clearfil Esthetic Cement EX, 20.7 ± 4.9; SpeedCEM, 17.8 ± 4.2; and Clearfil SA Cement, 7.2 ± 2.8. The results for the NaOCl exposure group were as follows: Variolink II, 24.0 ± 6.7; Multilink, 34.1 ± 6.1; Clearfil Esthetic Cement EX, 20.7 ± 6.8; SpeedCEM, 0.0 ± 0.0; and Clearfil SA Cement, 0.1 ± 0.1. The results for the 5-second sodium ascorbate group were the following: SpeedCEM, 8.5 ± 2.6, and Clearfil SA Cement, 4.3 ± 2.0. The following results were found for the 1-minute sodium ascorbate group: SpeedCEM, 12.2 ± 3.2, and Clearfil SA Cement, 4.8 ± 1.0. CONCLUSIONS: The resin cements tested varied in their capacity to adhere to NaOCl-treated dentin. Some resin cements exhibited equal or improved bond strengths (P < .05), whereas others exhibited significantly decreased bond strengths (P < .05). For the susceptible resin cements, a rinse of 10% sodium ascorbate provided an immediate restoration of at least 50% of the original bond strength (P < .05). The efficacy of sodium ascorbate may vary among resin cements.