Faculty Bibliography

This study evaluated the influence of different light-curing modes on the volumetric polymerization shrinkage and degree of conversion of a composite resin at different locations using micro-computed tomography and Fourier transform infrared spectroscopy (FTIR). Specimens were divided into 4 groups based on the light-curing mode used (Bluephase 20i): 1 -High (1,200 mW/cm2); 2 -Low (650 mW/cm2); 3 -Soft-start (650-1,200 mW/cm2); and 4 -Turbo (2,000 mW/cm2). Degree of conversion was calculated by the measurement of the peak absorbance height of the uncured and cured materials at the specific wavenumbers, and was performed by FTIR 48 h after curing resin samples. Degree of conversion was analyzed using two-way ANOVA. No significant differences were observed independent of the region of the restoration investigated (p>0.05). Different curing modes did not influence volumetric shrinkage neither degree of conversion of class I composite resin restorations.

Articulation and occlusion test materials are tools used in daily prosthodontic and restorative procedures that aid the clinicians in the evaluation of adjacent and opposing natural and/or artificial tooth contacts. A precision micrometer (Series 293, Mitutoyo, Japan) with a resolution of 0.001 mm was used to measure the thickness of five articulating papers and six articulation foils. Four of the articulating foils tested presented thicknesses inferior or equal to 21 mum, confirming their adequacy for the evaluation of natural dentitions. Clinicians and researchers should be aware that some labeled and actual papers/foils thicknesses are not in accordance. CLINICAL SIGNIFICANCE: The thickness of articulating papers and foils reported by some manufacturers is not accurate. The information provided in this article may aid clinicians and researchers to better select the most appropriate materials for the evaluation of static and dynamic occlusion.

STATEMENT OF PROBLEM: Few studies have investigated the voids and gaps produced during the cementation of fiber posts using different techniques. PURPOSE: The purpose of this study was to evaluate and quantify void and gap area formations of different fiber post cementation techniques using microcomputed tomography (muCT). MATERIAL AND METHODS: Standardized endodontically treated acrylic resin roots (N=24) were divided into 4 groups (n=6) according to different fiber posts cemented with the resin cement (FB); fiber posts relined with composite resin followed by cementation (FBR); fiber posts cemented using an ultrasonic device (FBU); and fiber posts relined with composite resin and cemented using an ultrasonic device (FBRU). Each specimen was scanned twice using micro-computed tomography (muCT; empty root, followed by after fiber post cementation). Digital imaging and communications in medicine (DICOM) files were transferred into 3-dimensional (3D) reconstruction software for analysis. Void volume in the cementation system and gap area formation were evaluated; quantitative and qualitative analyses were performed. The data were analyzed using 2-way ANOVA and the Tukey honest significant difference post hoc test (alpha=.05). RESULTS: FBR showed a lower percentage of voids than obtained for FB (P<.05). Groups FB, FBU, and FBRU did not show significant difference in void formation (P>.05). No significant differences were found in gap area formations among the experimental groups (P>.05). CONCLUSIONS: The use of a composite resin to reline the fiber post significantly decreased the void formation in the cementation procedure when no ultrasonic device was used. The use of an ultrasonic device did not decrease the percentage of void or gap formation for any technique evaluated.

This study evaluated the color variability of hues B, C, and D between the VITA Classical shade guide (Vita Zahnfabrik) and four other VITA-coded ceramic shade guides using a digital camera (Canon EOS 60D) and computer software (Adobe Photoshop CC). A cross-polarizing filter was used to standardize external light sources influencing color match. A total of 275 pictures were taken, 5 per shade tab, for 11 shades (B1, B2, B3, B4, C1, C2, C3, C4, D2, D3, and D4), from the following shade guides: VITA Classical (control); IPS e.max Ceram (Ivoclar Vivadent); IPS d.SIGN (Ivoclar Vivadent); Initial ZI (GC); and Creation CC (Creation Willi Geller). Pictures were evaluated using Adobe Photoshop CC for standardization of hue, chroma, and value between shade tabs. The VITA-coded shade guides evaluated here showed an overall unmatched shade in all their tabs when compared to the control, suggesting that shade selection should be made with the corresponding manufacturer guide of the ceramic intended for the final restoration.

This study evaluated the reliability of implant-supported crowns repaired with resin composites. Fifty-four titanium abutments were divided in three groups (n = 18 each) to support resin nanoceramic molar crowns, as follows: (LU) (Lava Ultimate, 3M ESPE); LU repaired with either a direct or an indirect resin composite. Samples were subjected to mouth-motion accelerated-life testing in water (n = 18). Cumulative damage with a use stress of 300 N was used to plot Weibull curves for group comparison. Reliability was calculated for a mission of 100,000 cycles at 400 N load. Beta values were 0.83 for LU, 0.31 and 0.27 for LU repaired with Filtek and Ceramage, respectively. Weibull modulus for LU was 9.5 and eta = 1047 N, m = 6.85, and eta = 1002 N for LU repaired with Ceramage, and m = 4.65 and eta = 766 N for LU repaired with Filtek (p < 0.10 between LU and LU repaired with Filtek). Reliability at 400 N was 100% for both LU and LU repaired with Ceramage which were significantly higher than LU Filtek repair (32%). LU restored crowns failed cohesively. Fractures were confined within the restored material, and detailed fractography is presented. The performance of resin nanoceramic material repaired with an indirect composite was maintained after accelerated-life testing compared to unrepaired controls. (c) 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

OBJECTIVE: This work aims to present a pilot study of a non-destructive dental histo-anatomical analysis technique as well as to push the boundaries of the presently available restorative workflows for the fabrication of highly customized ceramic restorations. MATERIALS AND METHODS: An extracted human maxillary central incisor was subject to a micro computed tomography scan and the acquired data was transferred into a workstation, reconstructed, segmented, evaluated and later imported into a Computer-Aided Design/Computer-Aided Manufacturing software for the fabrication of a ceramic resin-bonded prosthesis. RESULTS: The obtained prosthesis presented an encouraging optical behavior and was used clinically as final restoration. CONCLUSION: The digitally layered restorative replication of natural tooth morphology presents today as a clear possibility. New clinical and laboratory-fabricated, biologically inspired digital restorative protocols are to be expected in the near future. CLINICAL SIGNIFICANCE: The digitally layered restorative replication of natural tooth morphology presents today as a clear possibility. This pilot study may represent a stimulus for future research and applications of digital imaging as well as digital restorative workflows in service of esthetic dentistry.

OBJECTIVE: To evaluate the effect of light-curing wavelengths on composite filler particle displacement, and thus to visualize localized polymerization shrinkage in a resin-based composite (RBC) containing camphorquinone (CQ) and Lucirin TPO (TPO). METHODS: Three light-curing units (LCUs) were used to light-cure a RBC containing CQ and TPO: a violet-only, a blue-only, and a dual-wavelength, conventional (Polywave(R), emitting violet and blue wavelengths simultaneously). Zirconia fillers were added to the RBC to act as filler particle displacement tracers. LCUs were characterized for total emitted power (mW) and spectral irradiant output (mW/cm2/nm). 2-mm high, 7-mm diameter silanized glass cylindrical specimens were filled in a single increment with the RBC, and micro-computed tomography (mu-CT) scans were obtained before and after light-curing, according to each LCU (n=6). Filler particle movement identified polymerization shrinkage vectors, traced using software, at five depths (from 0 up to 2mm): top, top-middle, middle, middle-bottom and bottom. RESULTS: Considering different RBC depths within the same LCU, use of violet-only and conventional LCUs showed filler particle movement decreased with increased depth. Blue-only LCU showed homogeneous filler particle movement along the depths. Considering the effect of different LCUs within the same depth, filler particle movement within LCUs was not statistically different until the middle of the samples (P>.05). However, at the middle-bottom and bottom depths (1.5 and 2mm, respectively), blue-only LCU compared to violet-only LCU showed higher magnitude of displacement vector values (P<.05). Use of the conventional LCU showed filler displacement magnitudes that were not significantly different than blue-only and violet-only LCUs at any depth (P>.05). With respect to the direction of particle movement vectors, use of violet-only LCU showed a greater displacement when close to the incident violet LED; blue-only LCU showed equally distributed particle displacement values within entire depth among the samples; and the conventional LCU showed greater filler displacement closer to the blue LED locations. SIGNIFICANCE: Filler particle displacement in a RBC as a result of light-curing is related to localized application of light wavelength and total emitted power of the light emitted on the top surface of the RBC. When the violet LED is present (violet-only and conventional LCUs), filler particle displacement magnitude decreased with increased depth, while results using the blue-only LED show a more consistent pattern of displacement. Clinically, these results correlate to production of different characteristics of curing within a RBC restoration mass, depending on localized wavelengths applied to the irradiated surface.

STATEMENT OF PROBLEM: Few studies have investigated the volumetric polymerization shrinkage and film thickness of the different cementation techniques used to cement veneers. PURPOSE: The purpose of this in vitro study was to evaluate the volumetric polymerization shrinkage (VS) and film thickness (FT) of various cementation techniques through 3-dimensional (3D) microcomputed tomography (muCT). MATERIAL AND METHODS: Forty-eight artificial plastic maxillary central incisors with standard preparations for veneers were provided by a mannequin manufacturer (P-Oclusal) and used as testing models with the manufacturer's plastic veneers. They were divided into 8 groups (n=6): RelyX Veneer + Scotchbond Universal (RV+SBU); Variolink Esthetic LC+Adhese Universal (VE+ADU); Filtek Supreme Ultra Flowable + Scotchbond Universal (FF+SBU); IPS Empress Direct Flow + Adhese Universal (IEF+ADU); Filtek Supreme Ultra Universal + Scotchbond Universal (FS+SBU); IPS Empress Direct + Adhese Universal (IED+ADU); Preheated Filtek Supreme Ultra Universal + Scotchbond Universal (PHF+SBU); and Preheated IPS Empress Direct + Adhese Universal (PHI+ADU). Specimens were scanned before and after polymerization using a muCT apparatus (mCT 40; Scanco Medical AG), and the resulting files were imported and analyzed with 3D rendering software to calculate the VS and FT. Collected data from both the VS and FT were submitted to 1-way ANOVA (alpha=.05). RESULTS: VE+ADU had the lowest volumetric shrinkage (1.03%), which was not significantly different from RV+SBU, FF+SBU or IEF+ADU (P>.05). The highest volumetric shrinkage was observed for FS+SBU (2.44%), which was not significantly different from RV+SBU, IED+ADU, PHF+SBU, or PHI+ADU (P>.05). Group RV+SBU did not differ statistically from the remaining groups (P>.05). Film thickness evaluation revealed the lowest values for RV+SBU, VE+ADU, FF+SBU, and IEF+ADU, with an average between groups of 0.17 mm; these groups were significantly different from FS+SBU, IED+ADU, PHF+SBU, and PHI+ADU (P>.05), with an average of 0.31 mm. CONCLUSIONS: Both the VS and the FT of direct restorative composite resins were higher than those of veneer cements and flowable composite resins, whether preheated or not preheated.

PURPOSE: To show through computer-aided design and manufacturing technology combined with novel digital acquisition images and the right restorative material that the technology can provide an easier and predictable workflow for general practitioners. BASIC PROCEDURE: This case report presents a fully digital treatment of a 59-year-old patient with tooth-supported crowns and provides a detailed step-by-step digital technique to obtain a successful result. CONCLUSION: By avoiding traditional impression and fixed prosthetic techniques, excellent clinical results can be obtained, minimizing the required steps and simplifying the overall procedure. This adds information to the current literature, allowing general practitioners to choose the best treatment option. The function and esthetics remained unaltered over a 1-year follow-up period. No fracture or decementation was observed.