Evaluation of Marginal and Internal Fit of Ceramic Laminate Veneers Fabricated with Five Intraoral Scanners and Indirect Digitization.

The long-term success of ceramic laminate veneers (CLVs) is influenced by the marginal and internal fit of the restorations. However, studies comparing the fit of CLVs using different intraoral scanners or the indirect digitization technique are lacking. The purpose of this study was therefore to assess the marginal and internal fit of CAD/CAM-milled CLVs using different intraoral scanners and the indirect digitalization technique. An ivorine typodont maxillary left-central incisor was prepared; the tooth and the neighboring teeth were scanned and used as a template to print ninety 3D partial models. Thereafter, ceramic laminate veneers (CLVs) (N = 90) were milled from IPS-Emax CAD blocks and divided into six equal groups (15 specimens each) according to the type of intraoral scanner (IOS), as follows: Omnicam IOS, SC3600 IOS, Trios 3 IOS, Emerald IOS, I500 IOS. Fifteen further CLVs were fabricated using the conventional indirect digitalization technique. After cementation on the resin dies and embedding in clear epoxy resin, specimens were sectioned inciso-gingivally and mesio-distally. At the incisal and cervical positions, the marginal discrepancy was measured and evaluated in addition to the internal gap at six locations using SEM (200×). Differences between gap measurements among the six groups were determined using ANOVA. Games-Howell multiple comparisons for homogenous variances and LSD multiple comparisons for non-homogenous variances were used with 95% confidence intervals. The significance level was set at 0.05. The lowest mean absolute marginal gap at the incisal margins (AMGI) was recorded for Omnicam group (203.28 ± 80.14) µm, while the highest mean absolute marginal gap at the cervical margins (AMGC) was recorded for Omnicam group (147.16 ± 59.78) µm. The mean AMGC was reported to be significantly different between the conventional technique (146.75 ± 38.43) µm and Trios 3 (91.86 ± (35.51) µm; p = 0.001) and between Emerald (112.37 ± (50.31) µm; p = 0.042) and I500 (86.95 ± (41.55) µm; p 0.05). Marginal gaps were higher in the incisal region compared to the cervical region with both the indirect digitization technique and the IOSs. Ceramic laminate veneers (CLVs) fabricated using IOSs produced overall internal and marginal fit adaptation results comparable to CLVs fabricated from the indirect digitalization method, and both techniques produced clinically acceptable results

The effect of eugenol and non-eugenol endodontic sealers on the retention of three pre-fabricated posts cemented with a resin composite cement

PLEASE NOTE: This work is protected by copyright. Downloading is restricted to the BU community: please click Download and log in with a valid BU account to access. If you are the author of this work and would like to make it publicly available, please contact [email protected], 98 leaves : col. ill.Thesis (MSD) --Boston University School of Dental Medicine, 1999 (Prosthodontics).Includes bibliographic references: leaves 88-98.The effects of eugenol-containing endodontic sealer on the retention of posts cemented with resin cement are not well understood. The purpose of this study was to evaluate the retentive strengths of ParaPost XH dowels (Whaledent International, Mahwah, NJ), LogiPost dowels (RTD, Grenoble, France), and CosmoPost dowels (Ivoclar, Schaan, Lichtenstein) cemented with Panavia 21 cement in extracted teeth that were treated endodontically by using two different sealers (eugenol and non-eugenol). From approximately one hundred fifty premolars, sixty teeth of similar size and shape were selected. Canals were instrumented to a size 5 Profile file, rinsed with 2.6% sodium hypochlorite and obturated with gutta percha, half with a eugenol sealer and half with a non-eugenoI sealer. The two groups were then divided in three subgroups each. Post spaces for all teeth were prepared and all posts were cemented with Panavia 21 resin composite cement following the manufacturer’s recommendations and held in place with a 453g weight for 15 minutes. The failure load was measured with a universal testing machine (Instron Corp., Canton, MA) by applying a tensile force parallel to the long axis of the post, at a constant loading rate of 0.5cm/min. The results were statistically analyzed by using two-way ANOVA with Bonferroni multiple comparisons and Mann-Whitley U Test. There was no significant difference between the post and sealer factors (P=.967), or between the two endodontic sealers (P=.821). The mean maximal load for the LogiPost dowel was significantly greater than that for the CosmoPost dowel (P=.05). For both endodontic sealers, the mode of failure of the cement for the three post designs was significantly different. Retention of cement on the post was characterized by the following relationship: CosmoPost<LogiPost<ParaPost. There was no clear advantage to the use of a non-eugenol endodontic sealer when comparing retentive strengths of posts cemented with Panavia resin cement. Further research on the effect of the two studied sealers on other cements would be helpful; nevertheless it appears that the prognosis of a pulpless tooth restored with a prefabricated post will depend on factors other than ones studied in this investigation

A Comparison of the Surface Properties of CAD/CAM and Conventional Polymethylmethacrylate (PMMA)

Purpose To compare surface properties of 2 brands of pre‐polymerized resin blocks for complete dentures (CAD/CAM PMMA) to conventional heat‐polymerized PMMA. Materials and Methods A total of 45 rectangular specimens (25 × 25 × 3 mm) were fabricated from 3 brands of PMMA (n = 15/group): AvaDent CAD/CAM PMMA, Tizian‐Schütz CAD/CAM PMMA, Meliodent conventional PMMA. Specimens were examined for wettability using the sessile drop method, surface roughness using a digital contact profilometer, and microhardness using Vickers hardness number. Statistical analysis was performed using one‐way ANOVA and Tukey pairwise multiple comparisons. p‐Values of ≤0.05 were considered significant. Results AvaDent specimens demonstrated the highest mean contact angle (72.87 ± 48°) and the highest mean Vickers hardness number (20.62 ± 0.33). The conventional heat‐polymerized specimens showed the highest mean surface roughness (0.22 ± 0.071 μm). Tizian‐Schütz specimens showed the lowest mean surface roughness (0.12 ± 0.02 μm). Conclusions As CAD/CAM PMMA groups exhibited significantly more favorable surface properties in comparison to the conventional heat‐polymerized groups, CAD/CAM dentures are expected to be more durable. Different brands of CAD/CAM PMMA may have inherent variations in surface properties

Evaluation of Marginal and Internal Fit of Ceramic Laminate Veneers Fabricated with Five Intraoral Scanners and Indirect Digitization

The long-term success of ceramic laminate veneers (CLVs) is influenced by the marginal and internal fit of the restorations. However, studies comparing the fit of CLVs using different intraoral scanners or the indirect digitization technique are lacking. The purpose of this study was therefore to assess the marginal and internal fit of CAD/CAM-milled CLVs using different intraoral scanners and the indirect digitalization technique. An ivorine typodont maxillary left-central incisor was prepared; the tooth and the neighboring teeth were scanned and used as a template to print ninety 3D partial models. Thereafter, ceramic laminate veneers (CLVs) (N = 90) were milled from IPS-Emax CAD blocks and divided into six equal groups (15 specimens each) according to the type of intraoral scanner (IOS), as follows: Omnicam IOS, SC3600 IOS, Trios 3 IOS, Emerald IOS, I500 IOS. Fifteen further CLVs were fabricated using the conventional indirect digitalization technique. After cementation on the resin dies and embedding in clear epoxy resin, specimens were sectioned inciso-gingivally and mesio-distally. At the incisal and cervical positions, the marginal discrepancy was measured and evaluated in addition to the internal gap at six locations using SEM (200×). Differences between gap measurements among the six groups were determined using ANOVA. Games–Howell multiple comparisons for homogenous variances and LSD multiple comparisons for non-homogenous variances were used with 95% confidence intervals. The significance level was set at 0.05. The lowest mean absolute marginal gap at the incisal margins (AMGI) was recorded for Omnicam group (203.28 ± 80.14) µm, while the highest mean absolute marginal gap at the cervical margins (AMGC) was recorded for Omnicam group (147.16 ± 59.78) µm. The mean AMGC was reported to be significantly different between the conventional technique (146.75 ± 38.43) µm and Trios 3 (91.86 ± (35.51) µm; p = 0.001) and between Emerald (112.37 ± (50.31) µm; p = 0.042) and I500 (86.95 ± (41.55) µm; p 0.05). Marginal gaps were higher in the incisal region compared to the cervical region with both the indirect digitization technique and the IOSs. Ceramic laminate veneers (CLVs) fabricated using IOSs produced overall internal and marginal fit adaptation results comparable to CLVs fabricated from the indirect digitalization method, and both techniques produced clinically acceptable results

A Two-Year Comparative Evaluation of Clinical Performance of a Nanohybrid Composite Resin to a Flowable Composite Resin

Objective: This prospective in vivo study aimed to compare the clinical behavior of a flowable composite resin (Genial Universal Flo, GC) and a nanohybrid universal composite resin (Tetric Evo Ceram, Ivoclar Vivadent) used in Class I and II direct esthetic restorations in posterior teeth. Methods: A total of 108 Class I and II direct restorations were performed in patients aged between 20 and 60 years. The originality of this study lies in the fact that both materials were placed in pairs, in the same clinical environment (i.e., the same patient and the same type of tooth). The evaluations were performed now of restoration and after 2-weeks, 6-, 12-, and 24-months intervals using clinical examination, clinical photographs, and radiological examination, according to modified USPHS criteria. Statistical analysis was performed using the Fisher exact test and chi-square analysis. Results: At baseline, the universal composite resin showed better esthetic properties such as surface luster, surface staining marginal staining. Both materials regressed significantly over time with no significant difference between groups. Conclusions: Both flowable and nanohybrid composite resins exhibit acceptable clinical performance. The present 24 months of evaluation of different composites showed that the G-ænial Universal Flo could be an effective esthetic material for posterior restoration. No significant difference between both materials over time concerning surface luster, surface staining, and marginal staining

Influence of Denture Cleansers on the Retention Loss of Attachment Systems Retained Implant Overdenture

Background. This study aimed to evaluate the effects of different denture cleansing solutions (DCSs) on the retention of Locator and Locator R-Tx attachment systems of implant retained overdentures (IRO). Methods. Two part acrylic resin blocks were fabricated, upper part contained metal housing and plastic inserts and lower part contained implant analogs and abutments. Eighty pink plastic inserts (40/attachment, 10/solution) were immersed in Corega, Fittydent, sodium hypochlorite, and water for a time simulating upto 1-year of clinical usage. Acrylic blocks were held on a universal testing machine for a pull-out test to record the dislodgement force. Measurements were conducted after 6 months (T1) and 12 months (T2). One-way ANOVA followed by Tukey’s HSD test was used to analyze the results (α = 0.05). Results. For both attachments, retention significantly decreased after immersion in different solutions at T2 P<0.001. Locator R-Tx attachment in NaOCl showed a significant decrease in retention compared with other solutions at T1. At T2, there was a significant decrease in retention for all DCS compared with water P<0.001. Locator R-TX showed higher retention values per solution compared to Locator attachment P<0.001. In terms of retention loss %, NaOCl recorded the highest (61.87%) loss, followed by Corega (55.54%) and Fittydent (43.13%), whereas water demonstrated the best retention (16.13%) in both groups. Conclusion. Locator R-TX has better retention with different DCS immersion. The loss of retention varied with different types of DCS and NaOCl recorded the highest retention loss. Therefore, denture cleanser selection must be guided by the type of IRO attachment