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A 67-year-old male patient reported to the department with a chief complaint of tooth mobility. The patient presented with a medical history of diabetes for which he was on medication, and he also reported a history of chronic periodontitis. After a thorough assessment of the patient, a proper treatment plan was designed, which included full-mouth rehabilitation, prior to which the patient was advised full-mouth extraction. Six implants were inserted into the mandibular and maxillary arches as part of the treatment. After the implant was placed, zirconia was the preferred choice for the restoration because of its superior aesthetic results. Polyvinyl siloxane impression material was used to make implant impressions after an eight-week healing period. The case report provides the technique for the current approach to full-mouth rehabilitation with all six concepts of implant placement. In these situations, it is crucial to plan and insert implants correctly and adhere to the entire treatment plan. Restorations were performed using the latest computer-aided design/computer-aided manufacturing (CAD/CAM) technologies for a more aesthetically pleasing result. The case study highlights the significance of meticulous preparation and implementation for the accomplishment of successful full-mouth rehabilitation.

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No study has examined the simultaneous effect of facial forms, midline deviations and midline angulations on facial beauty. Therefore, this comprehensive study aimed to evaluate these and many other hypotheses. This psychometric study was performed on 15,042 observations. A female frontal photograph was edited to 45 perceptometric images with controlled anatomical alteration: 3 facial forms (euryprosopic [brachyfacial], mesoprosopic [mesofacial], leptoprosopic [dolichofacial]), each having either 9 bidirectional midline deviations (0, 1, 2, 3, and 4 mm deviated to the left and right) or 7 bidirectional midline angular deviations (0°, 5°, 10°, and 15° deviated to the left and right). One of the photographs were repeated. These 46 images were esthetically judged by 327 participants (243 laypeople, 49 orthodontists, and 35 'prosthodontists or restorative dentists'). Hierarchical mixed-model multiple linear regressions and post hoc tests were adopted to evaluate the simultaneous impacts of the photomodel's facial forms, midline deviations to the right or left, and midline rolls to the right or left plus sex, age, experience, and dental specialty of the referees on their perception of facial beauty as well as the tolerable zones of midline alterations. These were also done separately for each specialty group, and also for each facial face. Ideal combinations of anatomic features were determined using repeated-measures ANOVAs. Differences between esthetic preferences of different groups in terms of each image were assessed using one-way ANOVAs and t-tests (α = 0.05, α = 0.008, α = 0.001). All 5 anatomical features significantly and independently influenced perception of facial beauty. The tolerance threshold for midline deviations was 1 mm deviations to the right and left sides. For midline rolls, the only tolerable form was the no-roll ('on') midline; the judges preferred right-oriented defects over left-sided ones. The most beautiful facial form was mesoprosopic, followed by leptoprosopic. Men perceived the female face slightly more attractive than did women. The viewers' specialty (or lack of it), their age, or their experience did not affect their esthetic preferences. Predictors of esthetic preferences were all 5 anatomical features plus views' sex, but not their dental specialty, age, or experience. Zones of acceptability and also the ideal range of anatomical features were determined.

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Background: The aim of this study was to compare the fracture strength and fracture modes of post-cores produced with CAD-CAM from modified polyetheretherketone (PEEK) materials with other custom-produced post-cores. Methods: Sixty human mandibular first premolars with equal root sizes were used. The teeth were divided into six groups (n = 10), and root canal treatment was performed. The teeth were separated from the roots over 2 mm from the cemento-enamel junction. As a result of the decoronation process, a 1 mm wide shoulder line was obtained for all teeth. For the fracture strength test, 10 mm deep post spaces were created on the teeth with a 1.6 mm diameter driller. Post-core groups consisted: everStick® glass fiber post-core (Group GF), zirconia post-core (Group Z), metal (Cr-Co) post-core (Group M), PEEK post-core without filler (Group UP), PEEK post-core with 20% TiO2 Filler (Group TP), and post-core with 20% ceramic filler (Group CP). Following the application of posts to post spaces, copings were created and cemented on the samples. With the universal tester, a force was applied to the long axis of the tooth with a slope of 135°. The mean fracture strength (N) between the groups was statistically evaluated using one-way ANOVA, and pairwise mean differences were detected using post hoc Tukey's HSD test among the groups. Results: According to the results of the statistical analysis, a significant difference was found between the groups in terms of mean fracture resistance (p < 0.05). Group Z (409.34 ± 45.72) was significantly higher than Group UP (286.64 ± 37.79), CP (298.00 ± 72.30), and TP (280.08 ± 67.83). Group M (376.17 ± 73.28) was significantly higher than Group UP (286.64 ± 37.79) and Group TP (280.08 ± 67.83). There were no statistically significant differences between the means of the other groups (p > 0.05). Among all the groups, Group Z exhibited a higher prevalence of repairable failure modes, while the rest of the groups predominantly experienced irreparable failure modes. Conclusion: In our study, zirconia and metal post-core samples showed higher average fracture strength values than PEEK post-cores groups. Repairable failure modes were more common in the zirconia post-cores, whereas the opposite was observed in the other groups. Further experimental and clinical trial studies are needed before PEEK materials can be used as post materials in the clinic.

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PURPOSE: Additive cast-fabrication has yet to be used as commonly in implant prosthodontics as conventional methods. This review aimed to investigate the accuracy of additive cast-fabrication in implant prosthodontics. STUDY SELECTION: The study protocol was registered in the PROSPERO database (CRD42022374972). Reporting was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines, following the Cochrane Handbook. Two-arm interventional studies that matched the PICO were included (Population: dental typodonts with implants, Intervention: additive cast-fabrication, Comparator: conventional cast-fabrication, Outcome: positional deviations). A systematic search was conducted in three databases: PubMed (MEDLINE), EMBASE, and the Cochrane Library (CENTRAL). RESULTS: Seven papers were included in the analysis of horizontal, vertical, and root mean square (RMS) deviations. No significant differences were observed between groups. The overall vertical mean deviation of the intervention group was -4.15 µm [-24.88; 16.57], and the pooled mean absolute deviation was 22.43 µm [8.33; 36.54]. In the control group, these values were 19.67 µm [-32.71; 72.04] and 24.62 µm [0.00; 59.42], respectively. The overall horizontal mean deviation in the intervention group was 21.29 µm [-77.10; 119.68], and the pooled mean absolute deviation was 26.96 µm [0.00; 70.81]. In the control group, the overall mean was 1.45 µm [-32.26; 35.15] and the pooled mean absolute deviation was 25.05 µm [9.08; 41.01]. The mean RMS was only slightly larger in the intervention group, with the value of 14.74 µm [-107.26; 136.74]. CONCLUSIONS: Additive cast-fabrication is as accurate as the conventional method for the position of implant analogs.

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This study aimed to examine the impact of substrates, ceramic shades, and brands on the color and masking ability of highly translucent monolithic zirconia (HTMZ) using CIELab and CIEΔE2000 metrics. A total of 156 1-mm thick HTMZ disks in shades A1, A2, and A3 were produced using Dental Direkt and Kerox zirconia brands. Four 3-mm thick substrates (nickel-chromium alloy, non-precious gold alloy (NPG), zirconia shade A2, and resin composite shade A2) were prepared. HTMZ disks were overlaid on these substrates, and color measurements were taken with a spectrophotometer. Color differences (ΔE) were analyzed using CIELab and CIEΔE2000 formulas. The influence of brand, shade, substrate, and their interactions on ΔE values was assessed with a General Linear Model (GLM) and LSD pairwise comparison test. Spearman's correlation test examined the relationship between CIELab and CIEΔE2000 values. Results indicated that ΔEab was significantly influenced by substrate type and shade, while ΔE2000 was also affected by the ceramic brand. Mean color differences across ceramic-substrate groups were within clinically acceptable and perceptible ranges (clinically perceptible: ∆Eab ≥ 1.3 and ∆E2000 ≥ 0.8; clinically acceptable: 0.8 < ∆E2000 ≤ 1.8 and 1.3 < ∆Eab ≤ 2.7), except for NPG, which had ΔE values exceeding the perceptible range (ΔE2000: 1.1 ± 0.11 to 1.8 ± 0.31; ΔEab: 1.61 ± 0.15 to 2.16 ± 0.36). A significant correlation (r = 0.974, P < 0.001) was found between ΔEab and ΔE2000. Various ceramic brands and shades led to notable ΔE variations, yet average color differences within all ceramic-substrate groups remained clinically acceptable. Both ΔEab and ΔE2000 were reliable methods with a strong correlation for measuring color differences.

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BACKGROUND: Lack of patient contact in the pre-clinical prosthodontics curriculum makes it difficult for the students to comprehend and correlate the series of complex steps involved in complete denture fabrication. Early clinical exposure in the second year of the undergraduate program will facilitate a smooth transition of dental students from pre-clinics to clinics, thereby helping to mitigate the lacunae existing in the present curriculum. MATERIALS AND METHODS: A non-randomized prospective educational interventional study was conducted among 50 second-year dental students. Early clinical exposure in the form of clinical demonstration for complete denture steps of border molding and jaw relation was given subsequent to the completion of didactic and laboratory sessions. Pre- and post-multiple-choice question tests were conducted to explore students' knowledge. Student perception towards early clinical exposure was assessed using a self-administered anonymous questionnaire, while faculty perception was gauged with the help of in-depth interviews. RESULTS: A statistically significant difference was observed when pre- and post-multiple-choice question test mean scores were compared, showing an overall improvement in students' knowledge following early clinical exposure. Students and faculty held a positive perception towards the program and found it to be useful in enhancing the overall learning experience of the students. Faculty expressed their concern regarding limited manpower, paucity of time, and difficulty in integrating early clinical exposure into the present timetable. CONCLUSION: Early clinical exposure can be integrated into the traditional pre-clinical prosthodontics curriculum with appropriate time and manpower allocation. Faculty sensitization and training workshops need to be conducted before implementing this program.

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OBJECTIVE: To reveal need for prosthodontics in permanent teeth in children aged 8-18 years. MATERIALS AND METHODS: The study was performed in Khimki Dental Municipal Clinic. Dental examination and radiological studies were conducted in 97 primary patients aged 8-18 years. Indications for prosthodontics in permanent teeth were occlusal deterioration index more than 40% and crown decay of more than 50% in incisors and canines. Additional features were registered including DMFT index, the presence of extracted teeth and teeth after root canal treatment, as well and teeth with extensive restorations with resins and marginal seal quality. RESULTS: From 97 primary patients (27.8%) children needed prosthodontics in permanent teeth (in average 2.3±2.1 teeth): 1 tooth in 10 children, 2 teeth in 11 children, 3 teeth in 1 child, 4 teeth in 3 children and 4 teeth in 2 children. Mean DMFT was 8.1±4.5 teeth. Six children already had extracted permanent teeth (9 teeth in total). Half of the teeth (49.2%) which needed orthodontic treatment had history of root canal treatment while 46% needed primary or secondary endodontic treatment. Occlusal deterioration index was more than 40% in 41.3% of cases, more than 60% in 49.2% of teeth and more than 80% in 9.52% of teeth. From all the teeth restored with composite resins 41.7% had good marginal seal but 58.3% showed macroscopic signs of marginal leakage. CONCLUSION: Our study shows high percentage of adolescents having need for prosthodontics in permanent teeth and unjustified widening of indications for direct resin restorations in this group of patients.

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AIM: The present study aims to describe an in-house protocol for fully guided zygomatic implant surgery and prosthesis repositioning. MATERIALS AND METHODS: Four extramaxillary zygomatic dental implants (ZIs) were placed in one patient. The preoperative phase included digital planning, through which a surgical guide was designed and created. The analysis of the accuracy of guided surgery and the guided prosthesis repositioning was carried out by superimposing the digital planning with the final postsurgical implant positioning through CBCT. The radiologic evaluation included implant angular deviation, entrance and exit deviation, platform deviation, and apex apicocoronal and mesiodistal deviation. The prosthetic evaluation was performed in three directions: buccopalatal, apicocoronal, and mesiodistal. RESULTS: All the ZIs successfully osseointegrated after 3 months of healing, with no complications. The mean axial angular implant deviation was 0.52 ± 0.36 degrees, and the mean implant depth deviation was 0.47 ± 0.28 mm. The entrance and exit deviation of the implants was 0.74 ± 0.42 mm and 0.7 ± 0.43 mm, respectively. The virtual prosthesis was superimposed and compared with the standard tessellation language file of the provisional polymethyl methacrylate prosthesis at the level of the first molars and central incisors; the mean buccopalatal deviation was 0.6 ± 0.035 mm, the mean apicocoronal deviation was 0.65 ± 0.11 mm, and the mean mesiodistal deviation was 0.3 ± 0.07 mm. CONCLUSIONS: According to the results obtained in this first case of the present case series, careful and meticulous digital planning based on the correct prosthetic parameters can safely guide the performance of surgery.

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Digital technologies are gradually gaining ground in dentistry. In particular, taking impressions with intraoral scanners is becoming routine; however, even this must often be preceded by the use of retraction cords. This article presents an innovative technique to record digital impressions of natural tooth abutments using interim restorations relined with impression material instead of retraction cords. In the laboratory, using computer-aided design, the technician can segment the internal surface of the interim restoration and use it to replace the abutment of the intraoral scan, thus obtaining an accurate coping that yields more detailed information about the supragingival and intrasulcular surface of the preparation.

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In contemporary dentistry, several 3D printing techniques, including a stereolithography apparatus (SLA), digital light processing (DLP), liquid crystal display (LCD), and PolyJet 3D inkjet printing technology (PolyJet), are employed for model production. Despite their widespread use, there remains a paucity of the literature regarding the trueness and precision of these devices in dental applications. Existing studies comparing the accuracy of dental models manufactured by different printing technologies yield disparate conclusions regarding dental prosthesis manufacturing. This study aimed to test two null hypotheses: first, that the trueness of various new-generation 3D printers is equivalent, and second, that the trueness of printing by these printers is sufficient for achieving high-precision mastercasts in dental prosthodontics manufacturing. The research focuses on evaluating the trueness of five contemporary dental 3D printers: Anycubic Mono X 6Ks (Hongkong Anycubic Technology Co., Hongkong, China), Asiga Max (Asiga, Sydney, Australia), Creo C5 (Planmeca Oy, Helsinki, Finland), Form 3B (Formlabs, Boston, MA, USA), and J5 Dentajet (Stratasys Ltd., Eden Prairie, MN, USA). The methodology employed involved the creation of a digital test object using Blender software, adhering meticulously to the dimensions outlined in ISO standard 20896-1. These dimensions were chosen to be both relevant for this study and representative of clinical scenarios. Subsequently, the test object was printed and precise measurements were conducted utilizing a metrology-type Nikon XTH225 ST Reflection target in conjunction with VGStudio MAX analysis software. The results of our investigation revealed clinically negligible deviations in ball dimensions across all printers, with the maximum observed deviations ranging between 1.17% and 2.03% (notably observed in the Creo C5 printer). Transversal distortion exhibited variance based on the linear accuracy of each printer, with Stratasys21 and Formlabs 3B demonstrating superior accuracy among the evaluated printers. Distortions in the analyzed dimensions (specifically, anterior b-c, posterior a-d, and oblique a-c) were found to be uniform. In conclusion, while the first null hypothesis was rejected, indicating variations in trueness among the 3D printers assessed, our findings affirm the suitability of all five analyzed 3D printers for clinical applications. Consequently, these printers can be utilized for the fabrication of high-precision mastercasts in dental prosthodontics manufacturing.

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BACKGROUND: Residual ridge resorption presents obstacles in prosthodontic treatment, affecting denture stability and the success of dental implants. Genetic elements, specifically the single nucleotide polymorphism (SNP) 1772C>T variant within the hypoxia-inducible factor 1 subunit alpha (HIF-1α) gene, are hypothesized to contribute to residual ridge resorption progression. Nevertheless, its impact remains insufficiently investigated, especially within the context of South Indian populations. We sought to investigate the connection between SNP 1772C>T and residual ridge resorption (RRR) among fully edentulous individuals, considering demographic factors, genotyping methodologies, and statistical evaluations. METHODS: In a prospective case-control study, we recruited 100 completely edentulous participants from South India. Participants were categorized based on alveolar ridge height. Saliva samples were non-invasively collected for DNA extraction, and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis was employed to determine genotype distribution using the HphI restriction enzyme. The statistical evaluations comprised the utilization of chi-square and Fisher's exact tests. RESULTS: We observed no significant variations in genotype distributions between the case and control cohorts (CT: p=0.24; CC: p=0.65; TT: p=0.30). The heterozygous genotype CT was prevalent in both groups. CONCLUSIONS: Although we did not observe significant associations between SNP 1772C>T and RRR, our findings imply a genetic predisposition to residual ridge resorption that warrants further exploration. Variations in genetic susceptibility across ethnicities and the influence of other genetic variants on residual ridge resorption require additional investigation. This study lays the groundwork for personalized prosthodontic care by highlighting the potential of genetic analysis in routine dental practice to improve treatment strategies.

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The restoration of endodontically treated teeth (ETT) remains a significant challenge in modern dentistry. These teeth often suffer from substantial structural damage due to both the original pathology and the invasive nature of endodontic procedures. Consequently, ETT are more susceptible to fractures compared to vital teeth, necessitating restorative strategies that can effectively restore both function and aesthetics while minimizing the risk of failure. In recent years, advances in adhesive dentistry and the development of high-strength ceramics have further expanded the restorative options for ETT. Bonded restorations have gained popularity as they preserve more tooth structure and enhance the overall strenght of the tooth-restoration complex. The choice of restorative material and technique is influenced by numerous factors, including the amount of remaining tooth structure, the functional requirements of the tooth, and the aesthetic demands of the patient. Despite the plethora of available materials and techniques, the optimal approach to restoring ETT remains a topic of ongoing research and debate. In this comprehensive review, the current state of and recent advances in restoring damaged endodontically treated teeth are explored. Numerous therapeutic options exist, involving a wide range of materials. This article aims to present the biomaterial advancements of the past decade and their applications, offering alternative approaches to treating damaged ETT with the goal of prolonging their retention on the dental arch and serving as a valuable resource for dental practitioners who face this issue daily.

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OBJECTIVE: To assess the 2D and 3D natural symmetry of the maxillary incisors. MATERIALS AND METHODS: Maxillary alginate impressions were taken of 59 young adult volunteers. Gender, orthodontic treatment history, and dominant hand were collected. For 2D analysis, a digital caliper was used for measurements on maxillary casts. For 3D analysis, the casts were scanned using a lab scanner, and the labial surface symmetry of contralateral incisors was evaluated. Mann-Whitney tests and Student's t-test were performed, α = 0.05. RESULTS: Results indicated a lack of identical lengths among contralateral central or lateral incisors, with minimal occurrences of identical width measurements. 68% of central incisors and 73% of lateral incisors showed differences in length exceeding 0.2 mm. Central incisors showed more similarities than lateral incisors in width, with 61% central incisors and 47% lateral incisors having differences under 0.2 mm. The differences between highly asymmetrical contralateral teeth are situated at the transitional lines. The influence of sexual dimorphism, orthodontic factors, and the dominant hand on incisors' symmetry was not statistically significant. CONCLUSIONS: 2D and 3D symmetry of the natural maxillary incisors are rare. 3D symmetry remains consistent across orthodontic treatment status, gender, and dominant hand, suggesting its independence from such parameters. CLINICAL SIGNIFICANCE: To achieve a natural and aesthetic smile rehabilitation, the symmetry of the maxillary incisors must be well understood. In our study, 2D and 3D symmetry of the maxillary incisors occurred rarely, but central incisors showed more similarities than lateral incisors in width, with differences under 0.2 mm. On the other hand, differences between highly asymmetrical contralateral teeth are situated at the transitional lines. These conclusions should be included in further computer-assisted three-dimensional smile designs.

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BACKGROUND: The primary function of dental cement is to seal and support prosthodontic restorative materials. Proper selection of the dental cement contributes to the clinical success of the restoration. METHODS: A total of 166 molar tooth samples were prepared to simulate the type of tooth commonly found in prosthodontic practice. Each sample was restored using one of the tested dental cement materials employing a prestabilized methodology. The performance of resin-modified glass ionomer cement (RMGIC) (GC Fuji PLUS Capsule, GC America, Alsip, IL), zinc phosphate cement (ZPC) (Dentsply Sirona, Charlotte, NC), and resin cement (RC) (RelyX ARC, 3M ESPE, Saint Paul, MN) in bonding strength, marginal adaptation, and microleakage was evaluated and compared. The bonding strength, marginal adaptation, and microgroove were tested using specific established methodologies. The outcomes were then analyzed using statistical analyses for means and standard deviations to compare different types of dental cement. RESULTS: The total outcome shows that the highest bonding strength with the highest mean was the resin cement, rating 24.8 MPa, followed by RMGIC and ZPC at 20.5 and 18.9 MPa, respectively. The marginal adaptation scores indicate that RC had the highest score at a mean of 4, followed by ZPC at 3.2 and RMGIC at 2.5. The dye penetration measurements in millimeters revealed that ZPC had a penetration of 0.31 mm, RMGIC had a penetration of 0.25 mm, and RC had the least penetration at 0.20 mm. The results of the statistical data analysis show significant differences between the dental cements in bonding strength and marginal adaptation. CONCLUSION: In conclusion, resin cement demonstrated superior performance in bonding strength, marginal adaptation, and resistance to microleakage compared to RMGIC and zinc phosphate cement. These findings highlight the importance of selecting resin cement for achieving optimal clinical outcomes in prosthodontic restorations.

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BACKGROUND: In prosthodontics, dental impressions are essential for creating precise dental restorations. However, these impressions are susceptible to microbial contamination, which can pose a risk of infection to patients. Consequently, effective disinfection methods are crucial to prevent postoperative infections. This study aims to evaluate the effectiveness of various disinfection techniques for dental impressions used in prosthodontics. MATERIALS AND METHODS: A total of 148 poured dental impressions were randomized into three disinfection groups: immersed in 0.5% sodium hypochlorite, 2% glutaraldehyde, or 0.2% chlorhexidine solution. The bacterial contamination was evaluated by direct colony-forming unit (CFU) counting, while the dimensional accuracy and surface detail duplication of each resin sample were determined as physical properties. Data were analyzed using SPSS version 23.0 (IBM Corp., Armonk, NY). Either analysis of variance (ANOVA) with the option for post-hoc or non-parametric tests was used to investigate and compare the efficacy of the better disinfection protocols where the p-value was considered significant if less than 0.05. RESULTS: Glutaraldehyde showed the lowest mean CFU count (2.5 log10 CFUs), followed by sodium hypochlorite (3.2 log10 CFUs) and chlorhexidine (3.5 log10 CFUs). All disinfection protocols were able to significantly reduce microbial contamination when compared with the control group (p < 0.05). The results of the physical property assessment demonstrated acceptable dimensional accuracy in all tested protocols, with slight differences recorded between them regarding the reproduction of surface detail. More specifically, the mean dimensional deviation was in the range between 0.02 and 0.04 mm, while scores for surface detail reproduction ranged from 2 to 4. The ANOVA results revealed significant differences in microbial contamination levels (F(2, 145) = 5.72, p = 0.007) and dimensional accuracy (F(2, 145) = 3.45, p = 0.032) between the various disinfection protocols. CONCLUSION: This study enlightens the effective sterilization protocol to be adopted in prosthodontics for dental impressions. Glutaraldehyde was most effective in microbial reduction, while sodium hypochlorite and chlorhexidine were equally effective. Therefore, clinicians must be vigilant in assessing the type of microbial flora that can be encountered during prosthodontic procedures while choosing disinfection protocols for patient safety and quality of impressions.

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ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION: De Souza AB, Papaspyridakos P, Weber HP, Vazouras K, Matarazzo F. Effect of dental implant therapy on the preservation of orofacial tissues: A systematic review and meta-analysis. Clin Oral Implants Res. 2023;34 Suppl 26:240-256. doi:10.1111/clr.14106. PMID: 37750525. SOURCE OF FUNDING: No private or public funding was received for this research. CONFLICT OF INTEREST: The authors declare that they have no competing interests. TYPE OF STUDY/DESIGN: Systematic review (with meta-analysis).

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Background and Objectives: Gingival retraction is a critical pre-impression procedure in fixed prosthodontics, crucial for exposing tooth margins and ensuring accurate impressions for restorations like crowns and bridges. This study aimed to evaluate the absorptive capacity of different gingival retraction cords. Materials and Methods: Ninety samples each of Ultrapak (Ultradent, South Jordan, UT, USA) #00, braided cord, coreless thread, and monofilament thread (totaling 270 samples) were immersed in 0.9% NaCl, 10% aluminum chloride, and 12.7% ferrous sulfate solutions for 120, 300, and 1200 s. The liquid absorption capacity was measured using a gravimetric method, and the data were analyzed using an F-test, setting the significance threshold at p < 0.05. Results: The results revealed statistically significant differences in absorption, particularly for aluminum chloride and ferric sulfate (p < 0.001). Ultrapak demonstrated the highest absorption, followed by the coreless cotton thread, while the monofilament thread absorbed the least, especially at 1200 s. Conclusions: These findings indicate that Ultrapak's superior absorption could enhance moisture control during procedures, highlighting the importance of selecting an appropriate retraction cord for optimal clinical outcomes. Further research is needed to confirm these findings in a clinical setting.

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This study evaluated the effect of stearyl methacrylate addition on the physical and mechanical properties of bisphenol A glycidyl methacrylate- and triethylene glycol dimethacrylate-based polymers, which are traditionally used in dental applications. Methacrylate-based monomer compositions are polymerized under the visible blue light spectrum. An analysis of double bond conversion, surface microhardness test, three-point bending test and water sorption and water solubility were tested to determine the physical and mechanical properties of the dental polymers. The results indicated that stearyl methacrylate addition up to 25 wt% reduced the water sorption of the polymers. At amounts of stearyl methacrylate higher than 25 wt%, the solubility of the polymer in water increases due to the monofunctional structure. Mechanical properties are negatively affected by the increasing stearyl methacrylate ratio. Further, the addition of stearyl methacrylate slightly increased thermal stability. As such, the amount of stearyl methacrylate in a polymer composition is critical for the optimization of its mechanical and physical properties. According to the results, the amount of stearyl methacrylate has to be between 12.5-25 wt%.

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BACKGROUND: Achieving clinically adequate retention for cast crowns in prepared short abutments represents a major challenge for practicing dentists. Despite the important developments with adhesive cement, only a few teeth can be treated this way, and conventional preparation techniques are still employed for most crowns. Numerous options for auxiliary features exist; however, there is no consensus about one preferred method. This study aimed to evaluate the effect of a new innovative technique called the "double finish line technique" on full-crown retention for short abutments and to compare it with another modified preparation method. MATERIAL AND METHODS: A comparative in vitro experimental study was conducted at the Department of Fixed Prosthodontics, Damascus University. The study sample consisted of 30 chromium-cobalt abutments and 30 metal crowns. The sample was divided into three equal groups. The first group was a control group (CG) with a 20-degree total occlusal convergence, 3 mm height, and a 0.5 mm chamfer finish line. The second group had a reduced total occlusal convergence (TOC) in the cervical 1.5 mm of the axial wall from 20 to 8 degrees. The third group implemented the so-called "double finish line technique," adding another 0.5 mm chamfer finish line 1 mm above the first finish line (DFL group). The metal crowns were cemented to metal dies with zinc-phosphate cement. Pull-off tests were applied until failure. Data were analyzed, and the differences between the three groups were detected using one-way ANOVA followed by Bonferroni's post-hoc tests (p<0.05). RESULTS: The mean tensile strength values for the specimens were 115.36 (SD=14.59), 149.60 (SD=11.10), and 42.46 (SD=11.54) for the TOC, DFL, and CR groups, respectively. CONCLUSION: The reduced total occlusal convergence and double finish line techniques effectively increased full crown retention and resistance cemented on short abutments.