Light Polymerization through Glass-ceramics: Influence of Light-polymerizing Unit's Emitted Power and Restoration Parameters (Shade, Translucency, and Thickness) on Transmitted Radiant Power.

Background: This in vitro study assessed light transmission through ceramic discs varying in shade, translucency, and thickness using light-polymerizing units with different radiant power/flux (RP) outputs. Methods: Disc-shaped specimens (0.5 mm, 1.0 mm, and 2.0 mm) were made from high and low-translucency glass-ceramic ingots (IPS e.max Press) in shades A1 and A4, totaling 60 discs. Two light-polymerizing units with different power outputs were used, and their emission spectra were verified. The transmitted RP values for each ceramic specimen were measured and irradiance and radiant energy influx were calculated. Differences between the light-polymerizing units and the influence of the three ceramic parameters were evaluated using an independent-samples t-test and three-way analysis of variance (ANOVA) tests (α = 0.05). Results: A statistically significant difference was observed in the mean transmitted RP values between the two light-polymerizing units. Furthermore, the three-way ANOVA test showed a significant effect of shade, translucency, and thickness, as well as a significant interaction between each pair of variables and all three variables on the transmitted RP (P < 0.05). Conclusions: Despite the significant attenuation in the transmitted RP, especially in ceramics with higher shade chromaticity and thickness and lower translucency, the calculated minimal irradiance values for both light-polymerizing units (their emitted power ≥ 500 mW) were greater than the minimum recommended irradiance threshold (100 mW/cm2). However, the exposure duration needs to be increased to provide the resin with sufficient radiant exposure for adequate polymerization.

Evaluating the impact of scan body angulation and geometric attachments on the accuracy of complete-arch digital implant impressions: A comparison of two intraoral scanners.

PURPOSE: To investigate the effects of scan body (SB) angulation and geometric attachments (GAs) on the deviations of complete-arch digital implant impressions obtained using intraoral scanners (IOSs), in relation to the gold-standard desktop scanner. MATERIAL AND METHODS: Two IOSs (iTero and Omnicam), two SB angulations (0 degrees and 30 degrees), and GAs for the SBs were investigated. SBs were attached to an edentulous maxillary cast with the following implant analogs: parallel 0-degree at positions #13, #23, and #26, and 30-degree posteriorly tilted at position #16. The cast was digitized using a reference desktop scanner, followed by ten consecutive digital scans using each IOS (five scans with GAs and five without GAs, n = 20). Meshes obtained from the IOS scans were superimposed on the master reference mesh. Linear distance and 3D surface deviations from the reference mesh were calculated. A three-way multivariate analysis of variance (MANOVA) was employed to assess the effects of angulation, IOS type, and GAs on the combined dependent variables (α = 0.05). RESULTS: No significant three-way interaction was observed between IOS type, SB angulation, and GAs for combined deviations from the reference scan (p = 0.56). Simple main effect analysis revealed that iTero exhibited significantly lower mean 3D surface and linear deviations than Omnicam (p < 0.05). Additionally, the use of GAs significantly reduced deviations (p < 0.001), with mean deviation reductions for both scanners ranging from 26-33 micrometers (µm) for 3D deviations and 15-21 µm for linear distance deviations. No differences were found between angled and parallel SBs regarding 3D surface and linear distance deviations (p ≥ 0.05). CONCLUSIONS: ITero demonstrated significantly smaller deviations, and the use of GAs led to significantly reduced distance and 3D surface deviations. SB angulations did not impact scan deviations.

Evaluation of separating media for autopolymerizing acrylic resin fabricated on 3D-printed acrylate-based resin dental casts.

STATEMENT OF PROBLEM: Limited data are available regarding the most suitable separating medium for fabricating dental acrylic resin prostheses or appliances on 3-dimensional (3D)-printed resin casts. PURPOSE: The purpose of this in vitro study was to investigate and evaluate different separating media in terms of the ease of removal and detail reproduction of an autopolymerizing acrylic resin fabricated on acrylate-based 3D-printed resin casts. MATERIAL AND METHODS: A cube-shaped cast was designed with a built-in truncated cone-shaped hole and a V-shaped groove at the base. Seventy-five casts were 3D-printed using acrylate-based resin and assigned to 5 groups according to the applied separating media: Siliform BEA (silicone-based), IMPRIMO 3D (alginate-based), 3D Modellisolierung (wax-based), TECHNOSIL (alginate-based), and none (control). After the application of the separating media, the truncated cone-shaped holes in the specimens were filled with autopolymerizing acrylic resin. The efficacy of the separating media was evaluated according to the ease of removal on a scale of 1 to 3 and accurate detail reproduction of the V-shaped groove on a scale of 1 to 3 under ×6 magnification. The nonparametric Kruskal-Wallis rank test was used to identify significant differences among the separating media (α=.05). RESULTS: Significant differences were found among the groups (P<.001). Siliform BEA and 3D Modellisolierung had the best mean rank in both the ease of removal and detail reproduction scores, which were significantly different from those of the alginate-based separating media (IMPRIMO 3D and TECHNOSIL) and the control group (P<.01). CONCLUSIONS: The dedicated silicone- and wax-based separating media for 3D-printed casts exhibited the most favorable performance in terms of ease of removal and detail reproduction.

Evaluation of the marginal and internal fit of CAD/CAM crowns designed using three different dental CAD programs: a 3-dimensional digital analysis study.

OBJECTIVES: The purpose of this in vitro study was to assess and compare the marginal and internal fit of machine-milled crowns designed using three different CAD software programs. MATERIALS AND METHODS: Digital impressions of the master zirconia casts containing the prepared molar were obtained using an intraoral scanner. The obtained standard tessellation language (STL) files were imported into three CAD software programs (Multi-CAD, Blue-Sky CAD, and InLab), and crown designs were generated. Crown design digital STL files were used to mill crowns with a five-axis dental milling machine. The internal and marginal fits of the fabricated crowns over the master-prepared tooth were assessed using the triple-scan protocol and digital analysis techniques. The 3D marginal and internal fit values of the fabricated crowns from the designs generated by the three CAD programs were evaluated and statistically compared using one-way analysis of variance (ANOVA) and post hoc Tukey's tests (α = 0.05). RESULTS: There were no significant differences in the internal fit of the crowns designed by the three CAD programs (p > 0.05). However, there were significant differences in the mean marginal fit (p = 0.009) of the crowns. The marginal fit values for the InLab-designed crowns were significantly better than those for Multi-CAD (p = 0.03) and Blue-Sky CAD (p = 0.012) groups. CONCLUSIONS: All three CAD programs can design clinically acceptable crowns in terms of internal and marginal fit. InLab crowns outperformed the Multi-CAD and Blue-Sky CAD programs in terms of marginal fit. CLINICAL RELEVANCE: It is critical to test the ability of newly released CAD programs to design acceptable virtual crowns that can be transformed into actual crowns with optimal marginal and internal fit to existing clinical tooth preparations/conditions to ensure the high technical quality and long-term success of fabricated crowns.

Digitally Guided Workflow for the Esthetic and Prosthetic Oral Rehabilitation of a Patient with Excessive Gingival Display: A Case Report.

This report describes the esthetic and prosthetic oral rehabilitation of a patient with excessive gingival display using a digital guided workflow. As per this digital workflow, the patient's photographs, three-dimensional radiographic images, and a diagnostic digital intraoral scan were obtained. Preoperative digital case planning and designing were followed by the fabrication of surgical guides, printed casts, and matrices to accurately execute surgical esthetic crown lengthening and reproduce the digital design in the subsequent prosthetic rehabilitation.

Disinfection of implant abutment connection using antimicrobial photodynamic therapy and 0.2% chlorhexidine gel applications immediately before prosthesis delivery: Clinical and radiographic status at 1-year of follow-up.

OBJECTIVE: The aim of this 1-year follow-up randomized control trial was to compare the clinicoradiographic status of implants that were disinfected with antimicrobial photodynamic therapy (aPDT) and 0.2% chlorhexidine gel immediately before prosthesis delivery. METHODS: Forty-five partially edentulous patients with implants placed in the region of missing mandibular first molars and a history of periodontal diseases were included. Immediately before prosthesis delivery, patients were divided into three groups. In groups 1 and 2, implant abutment disinfection (IAD) was performed using aPDT and 0.2% chlorhexidine immediately before prosthesis delivery. In Group-3, IAD was performed using a steaming protocol. Peri-implant modified plaque index (mPI), modified gingival index (mGI), probing depth (PD) and crestal bone loss (CBL) were assessed at 1 year of follow-up. Power analysis was done and group comparisons were done. Logistic regression analysis was done to corelate clinical parameters with demographic variables. P<0.01 was considered statistically significant. RESULTS: In total, 15, 15, and 15 implants were present among patients in groups 1, 2 and 3, respectively. There was no statistically significant difference in peri-implant mPI, mBoP, PD and CBL in all groups (Table 2). None of the patients had periodontal disease and there was no statistically significant correlation between peri-implant clinicoradiographic parameters with age, toothbrushing and flossing habits, and duration of implants in function. Eighty percent, 86.7% and 100% individuals in groups 1, 2 and 3, respectively reported that they were brushing teeth twice daily. Flossing of interproximal spaces once daily was reported by 66.7%, 73.3% and 66.7% individuals in groups 1, 2 and 3, respectively. CONCLUSION: As long as oral hygiene is stringently maintained after implant prosthesis delivery, IAD can be performed using aPDT, 0.2% CHX gel or steam-disinfection.

Comparison of Peri-Implant Clinicoradiographic Parameters among Non-Smokers and Individuals Using Electronic Nicotine Delivery Systems at 8 Years of Follow-up.

PURPOSE: It is hypothesised the peri-implant soft-tissue inflammatory parameters (plaque index [PI], gingival index [GI], and probing depth [PD]) are poorer and crestal bone loss (CBL) higher around dental implants placed in electronic nicotine delivery systems (ENDS)-users than controls (individuals that had never consumed any form of tobacco). The aim of this study was to assess the peri-implant clinicoradiographic parameters among non-smokers and individuals using ENDS at 8 years of follow-up. MATERIALS AND METHODS: Self-reported non-smokers and individuals habitually using ENDS were included. A questionnaire was used to gather information about age in years, sex (female or male), daily frequency and duration of use of ENDS, family history of smoking and/or vaping, daily toothbrushing and flossing and most recent visit to a dentist or dental hygienist. These patients were evaluated for peri-implant CBL, PD, PI, BOP. The mesial and distal CBL was measured on digital bitewing radiographs that were taken using the long-cone paralleling technique. Group comparisons were statistically assessed and the level of significance was set at p < 0.05. RESULTS: One hundred twenty-seven individuals (92 males and 35 females) were included. Sixty-three individuals (46 males and 17 females) had used ENDS for 9.2 ± 0.8 years (group 1) and 64 (46 males and 18 females) did not use any nicotinic products (group 2). The mean ages of individuals in groups 1 and 2 were 34.2 ± 1.3 and 35.1 ± 0.5 years, respectively. In all patients, platform-switched dental implants with moderately rough surfaces were placed at bone level using an insertion torque of 30--35 Ncm. In both groups, implants had a diameter of 4.1 mm and the lengths ranged between 11 and 14 mm. In groups 1 and 2, implants were in function for 8.8 ± 0.4 and 8.5 ± 0.2 years, respectively. There was no statistically significant difference in mPI, mBoP, PD, and mesial and distal CBL around implants in groups 1 and 2 at 8 years of follow-up. CONCLUSION: Dental implants can demonstrate stable clinicoradiographic status and can remain functionally stable in non-smokers and ENDS users, provided that strict home oral hygiene measures are adopted.

Ten-year Survival Rate of Cement- and Screw-retained Restorations on Bone-level Dental Implants in Grafted and Non-grafted Sites: A Retrospective Study.

PURPOSE: The aim of the present 10-year follow-up study was to assess the survival rate of cement- and screw-retained restorations on dental implants placed in grafted sites. MATERIALS AND METHODS: Patients with cement- (group 1) and screw-retained (group 2) restorations on implants placed in grafted sites and patients with cement- (group 3) and screw-retained (group 4) restorations on implants placed in non-grafted sites were included. Demographic data was recorded using a questionnaire, and information regarding implant dimensions, surface characteristics, insertion torque, type of bone graft used, jaw location and duration of implants in function was retrieved from patients' records. These patients were evaluated for peri-implant crestal bone loss (CBL), probing depth (PD), modified plaque index (mPI), and modified bleeding on probing (mBOP). p < 0.05 was considered statistically significant. RESULTS: Eighty-eight partially edentulous individuals (n = 22 in each group) were included. The mean ages of individuals in all groups were comparable in all groups. In each patient, 1 bone-level platform-switched dental implant with moderately rough surfaces was placed using an insertion torque of 30-35 Ncm. In all groups, the length and diameter of implants ranged between 11-14 mm and 4.1-5 mm, respectively. There was no statistically significant difference in mPI, mBoP, PD, and mesial and distal CBR around implants in any of the groups. CONCLUSION: Bone-level implants restored with cement and screw-retained restorations can possess a stable clinicoradiographic status and remain functional in grafted and non-grafted sites, provided strict domestic oral hygiene measures are adopted and routine dental prophylaxis is carried out by oral healthcare providers.