Assessing color mismatch in single-shade composite resins for enamel replacement.

STATEMENT OF PROBLEM: Shade selection is a challenge in restorative dentistry. While single-shade composite resins may simplify this process, whether the color mismatch between this composite resin and the substrate is within acceptable levels to ensure successful outcomes is unclear. PURPOSE: The purpose of this in vitro study was to assess the influence of background and surrounding shade, thickness, and proximity to the surrounding on color mismatch when shaded and single-shade composite resins are used in the center of an enamel layer. MATERIAL AND METHODS: Two-layer specimens mimicking dentin (the background) and enamel (the surrounding and center) were prepared. Two shades were used for the background and the surrounding layer (OA1/A1 and OA3/A3). At the Ø3-mm center, 2 single-shade composite resins were placed, Omnichroma (OM) and Admira Fusion x-tra (FU), and also shaded composite resins A1, WE, A3, and C2. For the OA1/A1 background and surrounding, shades A1 and WE served as positive controls, while the A3 and C2 were negative controls. For OA3/A3, these controls were reversed. Two enamel layer thicknesses were evaluated (0.5- and 1.0-mm). Reflectance measurements were made at 0.0, 1.0, 2.0, and 2.5 mm from the center. Color differences were calculated between those at 2.5 mm and at other distances (ΔE0, ΔE1, and ΔE2). Data analysis employed a 4-way repeated measure ANOVA with Bonferroni corrections for the pair-wise comparisons (α=.05). RESULTS: Background and surrounding shade, central shade, distance, and thickness affected color mismatch (P<.05). For the OA1/A1 specimens, single-shade color mismatch values were found between both the positive and negative controls (P<.05). For the OA3/A3 specimens, the color mismatch did not differ significantly from that of negative controls (P>.05). No difference was found between ΔE0 and ΔE1, but each was distinct from ΔE2. Thickness did not affect the color mismatch of the single-shade composite resins (P<.05). CONCLUSIONS: Single-shade composite resins for enamel replacement showed higher color mismatches compared with positive controls.

The effectiveness of the supplementary use of the XP-endo Finisher on bacteria content reduction: a systematic review and meta-analysis.

OBJECTIVES: This systematic review evaluated the efficacy of the supplementary use of the XP-endo Finisher on bacteria content reduction in the root canal system. MATERIALS AND METHODS: In-vitro studies evaluating the use of the XP-endo Finisher on bacteria content were searched in four databases in July 2020. Two authors independently screened the studies for eligibility. Data were extracted, and risk of bias was assessed. Data were meta-analyzed by using random-effects model to compare the effect of the supplementary use (experimental) or not (control) of the XP-endo Finisher on bacteria counting reduction, and results from different endodontic protocols were combined. Four studies met the inclusion criteria while 1 study was excluded from the meta-analysis due to its high risk of bias and outlier data. The 3 studies that made it to the meta-analysis had an unclear risk of bias for at least one criterion. RESULTS: No heterogeneity was observed among the results of the studies included in the meta-analysis. The study excluded from the meta-analysis assessing the bacteria counting deep in the dentin demonstrated further bacteria reduction upon the use of the XP-endo Finisher. CONCLUSIONS: This systematic review found no evidence supporting the supplementary use of the XP-endo Finisher on further bacteria counting the reduction in the root canal.

Color assessment of resin composite by using cellphone images compared with a spectrophotometer.

OBJECTIVES: This study assessed the reliability of digital color measurements using images of resin composite specimens captured with a cellphone. MATERIALS AND METHODS: The reference color of cylindrical specimens built-up with the use of resin composite (shades A1, A2, A3, and A4) was measured with a portable spectrophotometer (CIELab). Images of the specimens were obtained individually or pairwise (compared shades in the same photograph) under standardized parameters. The color of the specimens was measured in the images using RGB system and converted to CIELab system using image processing software. Whiteness index (WID) and color differences (ΔE00) were calculated for each color measurement method. For the cellphone, the ΔE00 was calculated between the pairs of shades in separate images and in the same image. Data were analyzed using 2-way repeated-measures analysis of variance (α = 0.05). Linear regression models were used to predict the reference ΔE00 values of those calculated using color measured in the images. RESULTS: Images captured with the cellphone resulted in different WID values from the spectrophotometer only for shades A3 and A4. No difference to the reference ΔE00 was observed when individual images were used. In general, a similar ranking of ΔE00 among resin composite shades was observed for all methods. Stronger correlation coefficients with the reference ΔE00 were observed using individual than pairwise images. CONCLUSIONS: This study showed that the use of cellphone images to measure the color difference seems to be a feasible alternative providing outcomes similar to those obtained with the spectrophotometer.

Ultra-low frequency transcutaneous electric nerve stimulation does not affect the centric relation registration.

OBJECTIVE: To evaluate the influence of ULF-TENS on the displacement of the mandibular condyle and on the repeatability of centric relation (CR) registration of three different techniques: bimanual manipulation (BM), long strip technique, and harmonic centric occlusal relationship (R.O.C.A. wires). METHODS: Twenty-five participants without temporomandibular disorder (TMD) underwent two study stages conducted via electronic position analysis: (1) three CR records were made, one for each manipulation technique; (2) the ULF-TENS was applied for 30 min, and after that the same CR records were repeated. STATISTICAL ANALYSES: Mann-Whitney, ICC, and one-tailed F test. RESULTS: The ULF-TENS did not influence the condyle total displacement, regardless of CR recording technique used (p > 0.05). BM showed an improvement in repeatability after ULF-TENS. DISCUSSION: Concerning the variance, BM showed less variation at the X-axis. Long strip technique and R.O.C.A. wires varied less at the Y-axis. Long strip technique was again less variable at the Z-axis.

An evaluation of patients' knowledge about perioperative information for third molar removal.

PURPOSE: Third molar removal is usually accompanied by a high degree of patient anxiety. Lack of knowledge about the procedure is a major contributor to this anxiety. The aim of this study was to investigate the perioperative perceptions of patients who underwent extraction of third molars to assess their concerns during the surgical experience. MATERIALS AND METHODS: Issues related to preoperative, intraoperative, and postoperative phases of the experience were assessed with the purpose of identifying the most frequent questions and misconceptions. Data were assessed to correlate the influence of previous experience with extraction(s) with the appropriate knowledge of third molar surgery, as well as knowledge variations as to the age and gender of the patients. RESULTS: The sample was composed of 67 patients (43 female patients and 24 male patients) divided into 2 groups: The first had some previous experience with extractions (25 patients), and the second had no experience (42 patients). The most frequent questions regarded the number of teeth to be extracted (65.4%), and the most prevalent misconception was about medications before surgery (28.4%). Patients with a previous history of dental extractions had more questions about use of medication before surgery (P = .03). Patients without previous experience with extraction had more concerns about anesthesia techniques (P = .02) or the number of teeth that would be removed during the same procedure (P = .02). Other questions and misconceptions were not different between these groups. CONCLUSIONS: Patients with a history of tooth extraction and those without it presented different patterns of knowledge about third molar surgery. Both groups of patients needed detailed perioperative instructions about the procedure. These results may provide oral and maxillofacial surgeons with useful information about patients' knowledge throughout the surgical process.