Interocclusal records (IORs) created with bite registration materials (BRMs) accurately reflect the opposing teeth’s physiological and anatomical associations in digital and traditional dentistry. This study assessed the linear dimensional accuracy of vinyl polysiloxane-based scannable and transparent BRMs over obligatory clinical time intervals (1, 24, 72, and 168 h/s). A total of 3 scannable [Flexitime Bite, Occlufast CAD, Virtual CADBite] and 3 transparent [Maxill Bite, Charmflex Bite, Defend ClearBite] VPS-based BRMs were divided into 28 subgroups by time interval: 1, 24, 72, and 168 h/s. Stereomicroscope measurements of 420 standardised disk-shaped specimens with three distinct linear distances between crossing vertical and horizontal lines were taken. Comparisons with the conventional BRM determined the scannable and transparent BRMs’ accuracy, while comparisons with die dimensions yielded linear dimensional changes. Statistical analysis used median rank scores, interquartile range, and median. Using a one-way ANOVA rank and Dunn test, differences were assessed between and within groups at a probability ‘p’ value of 0.05 (p ≤ 0.05). Mean linear dimensions for CAD and transparent IOR materials were [−0.06 (−0.24%) to −0.15 (−0.6%)] and [−0.06 (0.24%) to −0.10 (0.40%)] millimetres, respectively. Virtual CADBite and Maxill Bite had the lowest linear disagreement after 1 h, but both showed significant variations at 7 days. Other commercial brands maintained their clinically acceptable linear accuracy (0.11). Flexitime Bite (CAD) was the sole material with a linear accuracy above the clinical threshold. IOR shrinkage reduced the linear dimensions in all materials. Until 7 days, all IOR materials except Flexitime bite (CAD) were clinically correct. Virtual CADBite and Maxill bite changed significantly during 1 h and 7 days.

BACKGROUND Chairside grinding, finishing, and polishing are essential for smoothing multilayered monolithic zirconia (MMLZ) restorations. Due to rubber matrix hardening, repeated sterilization of finishing and polishing instruments reduces their abrasive effectiveness. This study aimed to evaluate the effects of sterilization cycles on the effectiveness of 3 commercial polishing kits on the surface roughness of MMLZ crown restorations. MATERIAL AND METHODS One hundred milled, disc-shaped zirconia specimens (10 mm diameter, 3 mm thickness) were divided into 3 groups (n=30) based on the polishing kit used [EVE Diacera, SS White, Ultradent Jiffy]. Each group was further subdivided based on 1, 5, or 10 flash sterilization cycles (n=10). Profilometers measured average surface roughness while objective qualitative analysis was performed by scanning electron microscopy. A one-way ANOVA (Kruskal-Wallis) rank test and a post-hoc Dunn test with Bonferroni correction were used to determine the significance of median values and mean rank scores. The significance threshold for probability 'P' value was set at P≤0.05. RESULTS After 5 autoclaving cycles, the EVE Diacera group had a statistically significant increase in surface roughness (P=0.0009), which decreased somewhat after 10 cycles. The Ultradent Jiffy reduced surface roughness after repeated autoclaving, but SS White did not. Surface roughness did not change across groups after multiple autoclaving cycles, according to post-hoc analysis. CONCLUSIONS MMLZ surface roughness produced by all 3 polishing systems was clinically acceptable after 10 flash sterilization cycles. Ten flash sterilization cycles did not affect the efficiency of any of the polishing systems to produce a smooth surface on the MMLZ specimens.

Background:The thin descending limb of the loop of Henle is crucial for urine concentration, as it facilitates passive water reabsorption. Despite its importance, little is known about how this nephron segment forms during kidney development. Methods:We assembled a large single-cell RNA sequencing (scRNA-seq) dataset by integrating multiple datasets of non-mutant developing mouse kidneys to identify developing thin descending limb cells. To test whether those cells originate from proximal tubule cells, we generated a proximal tubule-specific Cre line, Slc34a1eGFPCre, and conducted lineage tracing. Additionally, given that the transcription factor Hnf4a directly binds to the Aqp1 gene, we examined whether the loss of Hnf4a affects Aqp1 expression in thin descending limb cells. Results:From our scRNA-seq dataset, we identified a small cluster of cells distinct from both the proximal tubule and the thick ascending limb of the loop of Henle. Those cells exhibited high expression of thin descending limb marker genes, including Aqp1 and Bst1. Notably, a subset of proximal tubule cells also expressed thin descending limb marker genes, suggesting that proximal tubule cells may give rise to thin descending limb cells. Using lineage tracing with the Slc34a1eGFPCre line, we found that, at least, a subset of thin descending limb cells are descendants of proximal tubule cells. Furthermore, the loss of Hnf4a, a transcription factor essential for mature proximal tubule cell formation, disrupted proper Aqp1 expression in thin descending limb cells, providing additional evidence of a developmental link between proximal tubule cells and thin descending limb cells. Conclusion:Our findings shed new light on the developmental origin of thin descending limb cells and highlight the importance of Hnf4a in regulating their formation.

Background: Maxillomandibular relationship records facilitate patient stomatognathic information transfer to dental laboratories, but new bite registration materials (BRMs) lack scientific evidence on linear dimensional accuracy. This in vitro investigation compared linear dimensional accuracy of 6 commercial scannable and transparent BRMs with a typical BRM at 1 h. Material/Methods: Seven American Dental Association (ADA)-approved BRMs were categorized into 1 control and 2 experimental groups: control: Occlufast Rock; scannable group: Occlufast CAD, Virtual CADBite, and Flexitime Bite; and transparent group: Maxill Bite, Charmflex Bite, and Defend ClearBite. The study used modified ADA specification no. 19 to standardize bite registration record samples, which were examined using a stereomicroscope to compare with control group and standard die measurements. Median, interquartile range, and median rank scores were used for statistical interpretation. One-way ANOVA (Kruskal-Wallis rank test) and multiple-comparison Dunn test with Bonferroni correction compared between and within group differences at the probability Pvalue <= 0.05. Results: The median linear differences varied in scannable,-0.06 (0.24%) to-0.11mm (0.44%), and transparent,-0.06 (0.24%) to-0.07 (0.28%), BRMs, with transparent BRMs showing more linear accuracy than scannable BRMs. A statistically significant difference from control at 1 h was observed for 3 different commercial brands. All transparent BRMs exhibited markedly reduced linear discrepancies, compared with the standard BRM (P<0.05). Conclusions: All BRMs at 1 h showed a reduced linear dimensions, indicating shrinkage. All investigated BRMs demonstrated clinically acceptable linear discrepancies, with transparent BRMs exhibiting less change than scannable BRMs.

BACKGROUND A tooth preparation's clinical requirements and geometric configurations should take precedence over material characteristics when advocating for putty reline impression techniques for permanent restorations, since they require a technically sensitive spacer for light body elastomer. We evaluated the linear dimensional accuracy of vinyl polysiloxane-based putty reline impressions with different spacer acquisition techniques in short-span and long-span fixed partial dentures (FPD). MATERIAL AND METHODS A typodont tooth set simulated a 3-unit (short-span) and a 5-unit (long-span) FPD. Between respective prepared abutments, 31 coordinates were identified and measured based on angles (line/point) and surfaces (curved/flat). Sixty impressions (dual stage 2-step putty reline technique) were divided into 5 groups (n=12/group): group PP (pre-preparation putty), group GP (gouging putty), group PS (polythene spacer), group CT (conventional temporary), and group MT (modified temporary), depending on spacer acquisition method. Coordinates measurements were conducted using a measuring microscope. Descriptive and inferential statistical tests (ANOVA, post hoc Tukey) determined between-group and within-group differences, at P≤0.05 significance level. RESULTS In short-span FPD, compared with control, the number of significantly different coordinates group-wise were GP (4 coordinates), PP (2 coordinates), and PS, CT, and MT (1 each). In long-span FPD, compared with control, the number of significantly different coordinates group-wise were group GP (12 coordinates), group PP (10 coordinates), group PS (5 coordinates), and group CT and group MT (4 each). CONCLUSIONS Different spacer acquisition methods produce varied thickness of spacers for relining of putty. CT and MT, when used as spacers, provided maximum accurate coordinates for angles (line/point) and surfaces (curved/flat).

This study determined the influence of surface treatment and protracted ageing on the shear bond strength (SBS) of orthodontic brackets bonded to CADCAM (milled) and 3D-printed polymethylmethacrylate (PMMA) provisional crowns (PCs). Eighty disc-shaped specimens [forty milled (CopraTemp WhitePeaks) [group (Gp) M] and forty printed (Asiga DentaTooth) (Gp P)] were divided into eight subgroups (Gp) based on surface treatment [no treatment (control) (Gp MC and Gp PC), coarse diamond (Gp MCD and Gp PCD), fine diamond (Gp MFD, and GP PFD) and sandblast (Gp MSB and Gp PSB)]. Orthodontic brackets were bonded (Assure Plus, Transbond XT), thermocycled (2200 cycles), and tested for SBS and failure (Adhesive Remnant Index) (ARI). Statistical tests included analysis of variance (ANOVA); Kruskal-Wallis (ARI ranks); and post hoc (Tukey, Dunn, and Bonferroni) for determining group differences at predetermined probability p-values less than 0.05. SBS was significantly increased in Gp MSB (15.51 Mpa) and Gp PSB (14.11 Mpa), while the coarse diamond subgroups yielded the lowest mean SBS values [Gp MCD (11.28 Mpa) and Gp PCD (11.62 Mpa)]. The SBS of subgroups MFD, MSB, PCD, and PSB showed significant differences from those of their respective controls (Gp MC and Gp PC). Low ARI scores were observed in Gp MC (0.40) and Gp MSB (0.80), while higher scores were observed in Gp PCD (2.10). Both milled and printed PCs fulfil the clinical criteria of the minimum SBS for orthodontic brackets for long-term use. However, milled PC has better SBS and low ARI scores, which make it more clinically feasible for orthodontic treatments.

Single-cell technology opened up a new avenue to delineate cellular status at a single-cell resolution and has become an essential tool for studying human diseases. Multiplexing allows cost-effective experiments by combining multiple samples and effectively mitigates batch effects. It starts by giving each sample a unique tag and then pooling them together for library preparation and sequencing. After sequencing, sample demultiplexing is performed based on tag detection, where cells belonging to one sample are expected to have a higher amount of the corresponding tag than cells from other samples. However, in reality, demultiplexing is not straightforward due to the noise and contamination from various sources. Successful demultiplexing depends on the efficient removal of such contamination. Here, we perform a systematic benchmark combining different normalization methods and demultiplexing approaches using real-world data and simulated datasets. We show that accounting for sequencing depth variability increases the separability between tagged and untagged cells, and the clustering-based approach outperforms existing tools. The clustering-based workflow is available as an R package from https://github.com/hwlim/hashDemux.

Background: The advent of digital impressions using computer-aided design and manufacturing technology (CAD/CAM) has simplified and improved the fabrication of implant prostheses in dentistry. The conventional impression has several drawbacks, including tray selection, material type, impression technique, impression disinfection, and cast model storage. The inaccuracies caused by distortion and contraction of impression material can be minimized with digital impressions. This study aimed to compare digital dental impressions of 10 working casts made using the Pindex laser removable die system to fabricate parallel drill channels vs 10 working casts made using the Di-Lok plastic tray removable die system. Material/Methods: An implant master die with 2 dental implant analogs was fabricated. Ten working casts using the Pindex laser removable die system with parallel drill channels and 10 working casts using the Di-Lok plastic tray removable die system were fabricated. The working casts were scanned using an extra-oral laboratory scanner and the implant master model was scanned with an intra-oral scanner. Results: The properties of the casts made using the 2 systems were evaluated and analyzed with ANOVA and post hoc Tukey test. The mean horizontal linear distances between A1B1 (P<0.021), A2B2 (P<0.018), C1D1 (P<0.026), C2D2 (P<0.03), B1C1 (P<0.01), and mean vertical distances between B1A2 (P<0.015), C1D2 (P<0.001), B1B2 (P<0.028), and C1C2 (P<0.001) were significantly different between the Pindex system and Di-Lok tray system as compared to intra-oral scans. Conclusions: Complete digital workflow with intra-oral scans were more than the partial digital workflow with extra-oral scans for the Pindex system and Di-Lok tray systems.

BACKGROUND: The nasopalatine canal (NPC), or incisive canal, is located in the midline of the palate, posterior to the maxillary central incisors. Its anatomy is important in prosthetic dentistry procedures. This study aimed to assess the anatomical morphology of the NPC according to age, sex, and dental status using cone-beam computed tomography (CBCT) in 335 patients. MATERIAL AND METHODS: In this retrospective cross-sectional study, a total of 335 patients were recruited and categorized according to sex, age, and dental status. Individual CBCT images were analyzed in the sagittal, coronal, and axial planes. Also, we recorded the dimensions and morphological shape of the NPC and adjacent buccal bone plate (BBP) under standardized conditions. The associations between sex, age group, NPC shapes and types, and presence of central incisors were assessed. A significance level was set at P<0.05. RESULTS: Mean labio-palatal and mediolateral measurements of the incisive foramen were 5.13 +/- 1.45 mm and 3.21 +/- 0.96 mm, whereas the mean diameter of Stenson foramen was 2.57 +/- 1.25 mm, and the total length of the NPC was 11.79 +/- 2.50 mm. Funnel, Y, and round-shaped canals were the most prevalent shapes of the NPC in sagittal, coronal, and axial planes. BBP was greater in men, with P=0.011, P=0.000, and P=0.001 at BBP1, BBP2, and BBP3, respectively. CONCLUSIONS: NPC and BBP parameter values were slightly higher among male patients. NPC parameters increased with older age. The crest width of BBP decreased with older age and after missing maxillary central incisor teeth.

Background: This study aims to perform a review by selecting, analyzing, and evaluating articles that discuss the accuracy of intraoral scanners (IOSs) in recording post space compared to conventional impression-making techniques. Methods: The review question framed using the PITR framework (participant, index test, targeted condition, and reference standard) is as follows: What is the dimensional accuracy (T) of impressions made using intraoral scanners (I) for post space (P) compared to impressions made using conventional techniques and digitalized using extraoral scanners (R)? Four electronic databases were searched using pre-set keywords. The guidelines and strategies recommended by PRISMA formed the basis for planning, executing, and documenting this systematic review. QUADAS-2 was used to critically analyze the quality of all the selected articles. Results: After excluding ineligible articles, the end synthesis has nine studies (n = 9) for qualitative analysis. All nine evaluated studies were found to be at risk of bias, with high or unclear risk in one or more domains. Three out of nine evaluated studies had unclear concerns regarding the applicability, and the remaining six had low concerns. In all the included studies, the IOSs were reported to have deviations in accuracy compared to the conventional techniques for making digital impressions of post space. Conclusions: The accuracy of IOSs was found to be inversely proportional to the length of post space and directly proportional to the diameter of post space. IOSs, when used adequately in short post spaces, can be an alternative to conventional impression-making for making custom posts and cores.

Background: Before insertion, chairside adjustment kits are heat sterilized for positioning and polishing dental restorations. This study aimed to evaluate the effects of 2 steam sterilization cycles on the efficacy of polishing highly translucent monolithic zirconia (HTMLZ) dental restoration material. Material/Methods: 100 HTMLZ disc-shaped specimens were adjusted (grinding, finishing, polishing) with EVE Diacera kit. Two steam sterilization techniques [standard (Gp S), immediate/flash (Gp (F)] of CAK were further subgrouped based on number of sterilization cycles [cycle 1 (control), cycle 5, 10, 15, and 20 (experimental)] (n=10 each). Each subgroup accordingly was evaluated for average surface roughness (Ra) and root mean square roughness (Rq) using a profilometer. Mean and standard deviation of 5 subgroups were statistically analyzed using one-way ANOVA/post hoc Tukey's test. Scanning electron microscopy complemented Ra, Rq measurements. Statistical differences of P <= 0.05 were considered significant. Results: HTMLZ specimens in both groups showed increased (Ra/Rq) values after repeated sterilization of EVE Diacera kit, with Gp F showing lesser increase than Gp S (20 cycles). Gp F at 10 cycles and Gp S at 15 cycles showed clinically unacceptable roughness threshold (0.25 mu m). Differences between subgroups for Ra and Rq values were significant ( P <= 0.05) with less differences within groups observed in early cycles (1, 10). Results validate the manufacturer's recommendations of using flash sterilization/10 cycles for EVE Diacera kit. Conclusions: Repeated sterilization reduces efficacy of chairside adjustment kit to produce smooth surfaces on HTMLZ. This study recommends flash sterilization to a maximum of 10 times to get the clinically acceptable results of Ra and Rq.

Background: This study used an edentulous mandibular resin model with 6 parallel osteotomy sites and aimed to compare the accuracy (trueness and precision) of 10 digital impressions using 3 intraoral scanners, the 3Shape TRIOS 5, Medit i700, and Primescan, using Medit Link v3.3.2 software. Material/Methods: A model simulating a patient's lower jaw was surgically prepared at 6 parallel sites (implant osteotomy), allowing placement of 6 implant analogues. Matrix-Direct transfer abutments were attached to the analogs, and a reference scan was obtained using a CeramilMap 600 extraoral scanner. Three intraoral scanners (3Shape TRIOS 5, Medit i700, and Primescan) made 10 digital impressions of each model. The data obtained were superimposed and compared using software (Medit Link 3.3.2) to evaluate accuracy. Mean values were statistically analyzed using one-way ANOVA and post hoc Tukey test. Differences were considered significant at a P value of less than 0.05. Results: The TRIOS 5 intraoral scanner displayed the lowest deviation for precision (37.8 +/- 4.53 pm) and trueness (54.9 +/- 11 pm), followed by Medit i700 (precision 40.6 +/- 4.17 pm, trueness 60.5 +/- 10.9 pm), whereas the highest deviation (precision: 49.1 +/- 8.31 pm, trueness: 72.3 +/- 10.4 pm) was reported when Primescan intraoral scanner was used for recording impressions of full arch implants. When the 3 intraoral scanners were compared, a statistically significant difference was observed in terms of precision (P<0.005) and trueness (P<0.005). Conclusions: TRIOS 5 intraoral scanner displayed the lowest deviation values for precision and trueness (more accurate), followed by Medit i700 and Primescan intraoral scanners. However, deviation values of all scanners were within clinically acceptable limits.

Vertical preparation techniques (VPTs), particularly the biologically oriented preparation technique (BOPT), have gained prominence in restorative dentistry due to their conservative approach to tooth structure preservation and improved aesthetic outcomes. This study aims to assess the knowledge and clinical practices of VPTs, including BOPT, among dental professionals in Sanaa, Yemen, and explore the barriers to their widespread use. An online cross-sectional survey was conducted among general practitioners and specialists in Sanaa, Yemen using a structured, self-administered questionnaire. The survey explored the participants’ knowledge, familiarity, and clinical use of VPTs and their perceptions of its advantages and challenges. Data were analyzed using descriptive statistics and Chi-square tests to evaluate associations between professional roles and VPT knowledge and practice. P values < 0.05 indicated statistical significance. Out of 285 participants, 76.8

BACKGROUND: Provisional fixed dental prosthesis (FDP) plays an important role during fixed prosthodontic therapy till the definitive. Discoloration of materials used for provisional FDPs can cause patient dissatisfaction and may create doubt about the color stability of the definitive FDP. Surface roughness is the other major property to be taken into consideration for provisional FDP materials. Smokeless tobacco is reported to affect the color stability and surface roughness of different prosthetic materials. OBJECTIVE: The aim of the current study was to evaluate the effect of two types of smokeless tobacco (black and white) on color stability and surface roughness of 3D printed, CAD/CAM milled, and conventional provisional FDP resin materials. METHODS: A total of 144 disc-shaped specimens were fabricated using four techniques CAD/CAM subtractive technique (milling), CAD/CAM additive technique (3D Printing), and conventional technique using autopolymerized PMMA, and autopolymerized Bis-acrylic resins. Each group was subdivided into three subgroups of twelve specimens each, and were submerged into three solutions (artificial salivary substitute, black smokeless tobacco, white smokeless tobacco). The change in color and surface roughness was evaluated and the data collected were statistically analyzed. RESULTS: It was observed that black smokeless tobacco caused the maximum color change and the effect was highest in autopolymerized PMMA resin specimens (ΔE = 9.343 ± 0.489), followed by 3D printed (ΔE = 7.187 ± 0.391), autopolymerized Bis-acryl (ΔE = 6.464 ± 0.453) and milled (ΔE = 4.978 ± 0.227). White smokeless tobacco was found to cause a maximum change in surface roughness and the effect was highest in autopolymerized Bis-acryl specimens (ΔRa = 0.321 ± 0.015 μm), followed by autopolymerized PMMA (ΔRa = 0.297± 0.015 μm), 3D printed (ΔRa = 0.191 ± 0.019 μm), and milled (ΔRa = 0.168 ± 0.014 μm). Statistically significant (p-value < 0.05) differences were observed among all techniques and solutions. CONCLUSIONS: The change in color and surface roughness were maximum in the case of FDPs prepared using autopolymerizing resins, followed by 3D printed, and CAD/CAM milled reins.

Background: For optimal clinical outcomes in full mouth rehabilitations, it is vital to determine the optimal jaw relations and confirm the appropriate vertical dimension of occlusion (VDO). The current study aims to evaluate various facial measurements as an adjunct in determining VDO in dentate individuals. Methods: A total of one hundred and twenty subjects, sixty males and sixty females, of the age group 19-30 were selected for the study. VDO (chin–nose distance) and other facial measurements like the glabella to subnasion (G-S) distance, both right and left pupil to rima oris (P-R) distance, both right and left corner of mouth to outer canthus of eye (M-E) distance, and both right and left ear to eye (E-e) distance were measured using a Vernier caliper. Results: The mean ± standard deviation of the C-N distance, G-S distance, right P-R distance, right M-E distance, left M-E distance, right E-e distance, and left E-e distance were 67.70 mm ± 3.22 mm, 60.29 mm ± 3.67 mm, 65.99 mm ± 3.72 mm, 66.00 mm ± 3.91 mm, 69.51 mm ± 3.71 mm, 69.48 mm ± 3.68 mm, 69.59 mm ± 3.98 mm, and 69.51 mm ± 3.95 mm, respectively. Pearson’s correlation coefficient between the C-N distance and M-E distance was found to be 0.739 (right), 0.730 (left); that between the C-N distance and E-e distance was found to be 0.738 (right), 0.732 (left); that between the C-N distance and P-R distance was found to be 0.660(right), 0.670(left); and that between the C-N distance and G-s distance was found to be 0.417. Conclusions: The present study reported a high positive correlation between the chin to nose distance and the distance between both the right and left lateral corner of the mouth to the outer canthus of the eye, and the distance between both the right and left ear to the eye. Hence, these measurements can be used as an adjunct for establishing VDO in the edentulous patient.

BACKGROUND:Several auxiliary features have been proposed to achieve sustainable retention for short-prepared dental crowns; however, achieving retention is challenging. This study aimed to assess the impact of increased total occlusal convergence and auxiliary preparation factors like box and groove on the retention form of short tooth preparations. MATERIAL AND METHODS:Eighty resin machine-milled dies with a height of 3 mm and a deep chamfer margin of 1 mm were prepared to mimic the short-prepared molar. Initially, 2 teeth were prepared following the guidelines, and the total occlusal convergence was kept at 10° and 20°, respectively. Auxiliary features such as the proximal box and buccal groove were prepared on separate 20° dies. Eighty dies were prepared with 10 samples each for 10°, 20°, 20° with proximal box and 20° with buccal groove for zirconia (n=40) and metal crowns (n=40). Cementation was done with glass ionomer luting cement, and a pull-off test was conducted. Data were analyzed using one-way analysis of variance and post hoc fisher least significant difference test (P<0.05). RESULTS:The highest mean was observed in the proximal box group with the metal crown (14.59), and the lowest in the group with 20° zirconia crowns (9.12). Within groups, the highest retentive values were found for the 20° taper with proximal box preparation; the lowest was for the 20° taper group. CONCLUSIONS:Within the study limitations, it could be concluded that incorporating a proximal box or buccal groove in short tooth preparations with an increased total occlusal convergence improved retentive values.

BACKGROUND Preshaded monolithic zirconia (MLZ) is reported to have high translucency. This study aimed to assess the effect of chlorhexidine gluconate (ChG) mouthwash on color and translucency parameter (TP) of 2 different preshaded MLZ dental ceramics after clinical adjustment. MATERIAL AND METHODS Two MLZ disk-shaped specimens [NPM (Nacera Pearl Multi-Shade) (n=72) and CZM (Ceramill Zolid FX Multilayer)] (n=72) were simulated for clinical adjustment, finished, and polished using 2 adjustment kits [recommended kit, third-party kit: Diasynt Plus and SUN (n=12 each)] and later immersed in ChG mouthwash (Avohex) for 2 weeks. Difference in color (ΔE) and TP (Y) were calculated using the CIELab formula after measuring the coordinates (Lab) with a colorimeter. Individual changes in color and TP were assessed on the Clinical acceptance (perceptible) threshold (CAT/CPT) and Translucency perception threshold (TPT), respectively. Differences between the 2 ceramics were assessed using one-way ANOVA and post hoc tests, with all differences considered significant at P<0.05. RESULTS NPM and CZM differed in color at baseline despite having the same Vita shade combination. Between the 2 preshaded MLZ ceramics, NPM showed significant changes in color when adjusted with a third-party kit. Chlorhexidine produced changes in color and TP that were designated as clinically perceptible (ΔE=1.0 to 3.3) on the CAT/CPT and TPT scales, irrespective of the adjustment kit used. ChG produced the least or no changes in glazed MLZ specimens. CONCLUSIONS ChG mouthwash, whenever prescribed for preshaded MLZ restoration, should be adjusted prior to final glazing to avoid clinical adjustments that adversely affects color and translucency of the restoration.

Objective: This study evaluated the effects of finish-line design, tooth preparation taper or total occlusal convergence (TOC), and digital production technology on the retention of provisional crowns for molars. Material and Methods: Different taper angles (10 degrees TOC and 20 degrees TOC) and finish line designs (chamfer and shoulder) were used to prepare four mandibular first molar teeth. Two subgroups of the prepared teeth received temporary crowns that were either "Computer-Aided Design" and "Computer-Aided Manufacturing (CAD/CAM) milled or 3D printed. Hence, eight test groups of temporary crowns containing 10 samples each were created. Groups 1-4 were milled, and Groups 5-8 were 3D printed specimens. A consistent procedure was used to cement 80 temporary crowns. The specimens were thermocycled for a total of 5000 heat cycles, initially at 5 degrees C for 30 s (dwell time) and then at 55 degrees C for 30 s. The pull-off force necessary to remove the temporary crowns was recorded, and the tensile strength, which served as the dependent variable, was calculated. Analysis of variance (ANOVA) was used to assess the variations in retention forces among the test groups. Results: The mean tensile strengths at maximum load [MPa] were higher in Groups 5, 6, 7, 8 (6.6 MPa, 6.91 MPa, 7.65 MPa, and 7.45 MPa respectively) as compared to the mean tensile strengths at maximum load [MPa] in Groups 1, 2, 3, 4 (2.35 MPa, 3.52 MPa, 3.21 MPa, and 2.45 MPa respectively). Conclusion: For extended periods, 3D-printed crowns with steeper preparation tapers (20 degrees TOC) and shoulder finish lines exhibited enhanced retention.

Tobacco consumption in its different forms can affect the optical and surface properties of dental materials that are used in the oral cavity. Thus, the present study was conducted to evaluate the effects of two commercially available smokeless tobacco products on the color stability and surface roughness of denture base resins that were fabricated using three different techniques (CAD/CAM milling, 3D printing, and conventional heat polymerization). A total of 126 denture base resin specimens were fabricated using the three different manufacturing techniques (n = 42 each). Specimens from each group were further subdivided into three subgroups (n = 14 each) and immersed in three different immersion media (a khaini suspension, a tabbaq suspension, and artificial saliva). The differences in color and surface roughness were assessed according to data that were collected and statistically analyzed using SPSS version 24.0. The tabbaq smokeless tobacco was found to cause greatest changes in color and surface roughness; the effect was observed to be highest in the 3D-printed specimens followed by the conventional heat-polymerized and CAD/CAM milled specimens. The mean changes in color and surface roughness were the highest for the tabbaq smokeless tobacco followed by the khaini smokeless tobacco and the artificial saliva. Statistically significant (p-value < 0.05) differences were observed among all techniques and suspensions. We concluded that the mean changes in color and surface roughness were significantly higher for the 3D-printed dentures compared to the conventional heat-polymerized and CAD/CAM-milled dentures. Thus, the results of the present study strengthened the concept that tobacco in any form can lead to changes in the color and surface roughness of denture base materials.

Background and Objectives: The use of desensitizing agents (DA) after tooth preparation to prevent hypersensitivity is well documented in the literature. A fixed dental prosthesis (FDP) should have good retention to be successful. Inadequate retention may result in microleakage, secondary caries, and, eventually, dislodgement of the FDP. The effect of DAs on the retention of FDPs has been widely studied in the literature, but the results are conflicting. Thus, this study aimed to conduct a systematic review to assess the effect of dentine desensitizing agents, used to prevent post-cementation hypersensitivity, on the retention of cemented FDPs. The null hypothesis framed was that there is no effect of dentine desensitizing agents on the retention of cemented FDPs. The focused PICO question was as follows: “Does the application of dentine desensitizing agents (I) affect the retention (O) of cemented fixed dental prosthesis (P) when compared to non-dentine desensitizing groups (C)”? Materials and Methods: Four electronic databases were systematically searched and, on the basis of the predefined inclusion and exclusion criteria, 23 articles were included in this systematic review. A modified CONSORT scale for in vitro studies was used to assess the quality of the selected studies, as all included studies were in vitro studies. Results: Most of the studies compared the effect of more than one type of DA on retention. The results of the selected studies varied due to differences in the composition of tested dentine DAs and types of luting cements. Conclusions: Within the limitations of this study, it can be concluded that the retention values of FDPs cemented using zinc phosphate cement were reduced with most of the DAs, whereas retention values increased when GIC, resin-modified GIC, and resin cements were used with the majority of DAs. These findings are important, as they can guide dentists in selecting the DA before cementing the crowns with the luting agent of their choice, without compromising the retention of the crowns.