Browsing by Author "Levon, John"

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    Effect of silver diamine fluoride on the prevention of erosive tooth wear in vitro
    (Elsevier, 2020) Ainoosah, Sultan E.; Levon, John; Eckert, George J.; Hara, Anderson T.; Lippert, Frank; Cariology, Operative Dentistry and Dental Public Health, School of Dentistry
    Objectives To investigate the ability of silver diamine fluoride (SDF) to prevent erosive tooth wear in enamel and dentin. Methods SDF (38 %) was compared to deionized water (DIW, negative control), potassium fluoride (KF, fluoride control), silver nitrate (AgNO3, silver control), and fluoride varnish (FV, clinical reference) using erosion and erosion-abrasion cycling models. Bovine enamel and dentin slabs were embedded in resin blocks. Two resin blocks were glued to form study blocks (n = 8, per treatment), one for erosion and the other for the erosion-abrasion model. The blocks were treated once and then subjected to a five-day cycling model, with five daily citric acid erosive challenges (0.3 % citric acid/pH 2.6). Abrasion was performed using a toothbrushing machine with a medium-abrasive silica as abrasive (erosion-abrasion model only). Artificial saliva was used to remineralize the specimens after erosion/abrasion and as storage media between cycles. Surface loss (SL) was determined by non-contact profilometry. Data were analyzed using ANOVA (α = 0.05). Results Both eroded-abraded enamel and dentin specimens exhibited significantly more SL in all treatment groups than the only eroded ones (p < 0.001). For dentin, both AgNO3 and DIW groups had significantly more SL than SDF, KF, and FV groups (p < 0.001), for both models. For enamel, specimens had more SL in both AgNO3 and DIW groups compared to SDF, KF, and FV groups, in the erosion model. When enamel specimens were subjected to erosion-abrasion, FV resulted in the least SL (p < 0.001). Conclusion SDF was effective in reducing dental erosion on both substrates, but dental erosion-abrasion only on dentin. Clinical significance SDF may become a viable intervention for ETW prevention in dentin (e.g. exposed roots) once its efficacy has been confirmed under clinical conditions.
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    Extrinsic Characterization Sustainability in Zirconia Reinforced Lithium Silicate Ceramics
    (2021-04-08) Gadah, Thrya; May, Jaren; Levon, John; Chu, Tien-Min G; Gregory, Richard; Wei Shao, Lin; Feitosa, Sabrina
    ABSTRACT OBJECTIVE. To investigate the effect of aging on the surface roughness and the color sustainability of externally characterized zirconia reinforced lithium silicate glass-ceramics treated with different surface protocols. METHODS. Sixty blocks (12-mm X 14-mm; 1.5-mm) of pre-crystalized zirconia reinforced-lithium silicate glass-ceramic (Vita Suprinity, Vita Zahnfabrick, Germany) CAD/CAM were crystalized and treated with different surface protocols, as extrinsic characterization (EC), mechanical polishing (MP), glaze layer (GL), surface adjustment (SA) and no treatment – control group (CG). Experimental groups (n=10) were divided as follow: CG; EC-MP-GZ; EC-GZ; EC-MP; EC-GZ-SA-GZ; EC-GZ-SA-MP and submitted to thermocycling (5,000 cycles, 5-55C) and toothbrushing simulation (5,000 cycles). Surface roughness (Ra and Rq), color change (CIED2000) and biofilm growth were evaluated. Statistical analysis was performed with a two-sided 5% significance level for all tests. RESULTS. For the parameter RaX, the control differed from EC-GZ and EC-MP (p = 0.04). For the parameter RqX, EC-GZ presented higher surface roughness compared than EC-MP-GZ and the group EC-GZ-SA-MP (p=0.02). EC-MP (p<0.01) and the EC-GZ-SA-MP (p<0.01) showed higher color change E00 after aging, while CG and EC-MP-GZ the least. For the biofilm growth, no significant group effect on bacteria counts was found (p=0.089). CONCLUSION. The aging protocol affected the surface roughness, and color of externally characterized zirconia reinforced lithium silicate glass-ceramics submitted to different surface treatment protocols. In the present study, when the mechanical polishing was performed before glaze application, the slightest color change and surface roughness were observed compared to the other surface treatments. Bacteria were not able to grow in the material surface, under the conditions tested in the present study.
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    Fabricating Tooth supported Overdenture using locators® as a method of retention :case report.
    (4/13/2015) Alzayer, Yasmin; Levon, John; Alzayer, Yasmin; Levon, John; Prosthodontics
    Tooth supported complete overdentures have been a treatment option for decades and they provide the patient with proprioception (the awareness of jaw-space relationships) which is normally lost when teeth are extracted. In addition, the overdenture provides the patient with improved biting force and neuromuscular control. The objective of this case presentation is to discuss a technique used to fabricate complete tooth supported overdenture. Assessments: 80 year old African American female presented to Graduate Prosthodontic Clinic at IUPUI complaining of difficulty in chewing food due to her partially edentulous mandible. Her medical history revealed a history of hypothyroidism, osteoarthritis, rheumatoid arthritis and hypertension. In 2013 root canal treatments were done to #22, 27 with post space preparations. Intraoral examination revealed a resorbed mandibular residual ridge. The prosthodontic treatment plan was to retain these two teeth and attach Locators® to them to improve the retention of the denture. Impression was made of both post spaces and posts were waxed up on the master cast. Castto-Locator® attachments were incorporated in the wax ups, which were invested and cast in Type III Gold Alloy. The final posts with Cast-to-Locator® attachments were cemented with resin cement. Finally, the mandibular complete overdenture was adjusted and delivered to the patient. Evaluation: the Locator® attachments were stable in the gold posts without any neither periapical pathology nor gingival inflammation. In addition, the patient was able to properly clean the remaining root and the internal surface of the denture. In conclusion: This technique resulted in a very satisfying and retentive denture for the patient while utilizing minimum invasive procedures.
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    Flexural strength comparison of monolayer resin composite to bilayer resin/ liner composite
    (2009) Azzam, Mai; Platt, Jeffrey A.; Levon, John; Taskonak, Burak; Brown, David; Andres, Carl; Legan, Joseph
    Clinical evidence suggests that the use of liners in posterior composite restorations may increase the frequency of restoration fractures. Materials that have been used as liner materials for resin composite (RC) restoration include conventional glass ionomers, resin-modified glass ionomers (RMGI), and flowable composites. The aim of this study was to compare the flexural strength of a monolayer of resin composite with that of a bilayer of resin composite and liner. Four types of RC beams were tested: a monolayer control that is an un-lined RC (Tetric EvoCeram, Ivoclar Vivadent) and three “bilayer” specimens that consisted of this same RC lined with one of three liners. The three liners used included two RMGI cements (Vitrebond LC liner; 3M ESPE and, GC Fuji Lining LC; GC America) and a flowable resin composite (Tetric EvoFlow, Ivoclar Vivadent). Each group was tested after water storage for 24 h and 30 d. Altogether, eight, 12-specimen groups were fabricated and tested. Methods: A 25 x 2 x 2 mm mold was completely filled with the RC to form the control beams. To form the bilayer beams, this mold was filled with 0.5 mm of the liner and then with 1.5 mm of the RC. Specimens were stored in 37oC distilled for either 24 h or 30 d. Immediately prior to testing, the 30-day groups were also thermocycled 2500 times, between water baths at 7 oC and 48oC with a 30-s dwell time and a 10-s transit time. Flexural strength was determined using a three-point–bending device. A twoway analysis of variance (ANOVA) with interactions was used to investigate how liner group (or no liner) and storage time affected strength. Results: The interaction between liner type and storage time was significant (p = 0.0128). The un-lined RC (the monolayer beam) was significantly stronger after 24 h than after 30 d in water (p = 0.0098). Water storage between 24 h and 30 d did not change the flexural strength of any of the bilayer (lined) beams (p > 0.05). After storage for 24 h and also for storage for 30 d, both un-lined RC and RC lined with the flowable RC exhibited significantly higher flexural strength (p = 0.0001) than the bilayer beams lined with either RMGI liners.
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    Importance of Vertical Dimension in Facial Esthetics.
    (04/13/15) Supornpun, Noppamath; Levon, John; Supornpun, Noppamath; Levon, John; Aesthetic Dentistry
    The objective is to discuss the importance in the determination of the vertical dimension of occlusion in prosthodontic treatment. Case I: A 43-year-old Caucasian female presented with chief complaints of both poor function and esthetics. The medical history revealed a history of cirrhosis, Hepatitis B and depression. In 2011, she presented edentulous with some lower impacted teeth. Three sets of complete dentures were fabricated and delivered. These dentures caused her various problems including complaint of the thick and overextended borders, unacceptable esthetics and ear pain. Due to lack of posterior inter-occlusal space, vertical dimension was increased so much that the resulting dentures were unsatisfying esthetically and auricular discomfort. Case II: A 75-year-old Caucasian male presented with a chief complaints of a broken denture, joint discomfort and esthetic concern. The medical history revealed a history of angina pectoris, hypertension and depression. He continuously complained about his joint pain and broken prosthesis since 2011. Repairs were done several times but they did not eliminate his problem. In 2013, he was diagnosed with a loss of vertical dimension. When his vertical was reestablished at its proper position, his joint discomfort was resolved and his esthetics was greatly improved. Conclusion: Determination of the proper vertical dimension of occlusion is a crucial factor in the overall success of a restorative case. For correct diagnosis and treatment, the restorative dentist should use past dental history, facial profile, past photographs, provisional prosthesis and mounted diagnostic casts.
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    Marginal Fit, Mechanical Properties, and Esthetic Outcomes of CAD/CAM Interim Fixed Dental Prostheses (FDPs): A Systematic Review
    (MDPI, 2023-02-28) Al-humood, Hussain; Alfaraj, Amal; Yang, Chao-Chieh; Levon, John; Chu, Tien-Min Gabriel; Lin, Wei-Shao; Prosthodontics, School of Dentistry
    This systematic review aimed to study the outcomes of CAD-CAM (milled and 3D-printed) interim dental prostheses when compared to conventional ones. The focused question of "In natural teeth, what are the outcomes of CAD-CAM interim FDPs compared to the conventionally-manufactured ones regarding marginal fit, mechanical properties, esthetics, and color stability" was formulated. The systematic search was conducted electronically in the PubMed/MEDLINE, CENTRAL, EMBASE, Web of Science, New York Academy of Medicine Grey Literature Report, and Google Scholar databases by using the MeSH keywords and keywords associated with the focused question and limiting articles to those published between 2000 and 2022. A manual search was conducted in selected dental journals. The results were analyzed qualitatively and are presented in table format. Of the included studies, 18 studies were in vitro and 1 was a randomized clinical trial. Of the eight studies analyzing the mechanical properties, five studies favored the milled interim restorations, one study favored both 3D-printed and milled interim restorations, and two studies reported better mechanical properties in conventional interim restorations. Among four studies evaluating the marginal discrepancies, two studies favored the marginal fit in milled interim restorations, one study reported a better marginal fit in both milled and 3D-printed interim restorations, and one study found conventional interim restorations have a better marginal fit and smaller marginal discrepancy when compared to both milled and 3D-printed restorations. Among five studies that evaluated both the mechanical properties and marginal fit, 1 study favored 3D-printed interim restorations and four studies favored milled interim restorations over the conventional ones. Two studies analyzing the esthetics outcomes demonstrated better results with milled interim restorations compared to conventional and 3D-printed interim restorations in terms of their color stabilities. The risk of bias was low for all the studies reviewed. The high level of heterogeneity within the studies excluded meta-analysis. Most of the studies favored the milled interim restorations over the 3D-printed and conventional restorations. The results suggested that milled interim restorations offer a better marginal fit, higher mechanical properties, and better esthetic outcomes in terms of color stabilities.
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    Nicotine Upregulates Coaggregation of Candida albicans and Streptococcus mutans
    (Wiley, 2017) Ashkanane, Ali; Gomez, Grace F.; Levon, John; Windsor, Jack; Eckert, George J.; Gregory, Richard L.; Biomedical and Applied Sciences, School of Dentistry
    Purpose Denture stomatitis is a condition of painless inflammation of denture-bearing mucosa. Reports indicate that nicotine, the major psychoactive ingredient in tobacco, increases growth of Streptococcus mutans and Candida albicans in denture biofilm. The purpose of this study was to determine the in vitro effects of nicotine on coaggregation of C. albicans with S. mutans. Material and Methods C. albicans strain ATCC 10231, S. mutans strain UA159 (ATTC 700610), and nicotine dilutions (ranging from 0 to 32 mg/ml) were used for this study. Both microorganisms were grown for 24 hours in dilutions of nicotine (0 to 32 mg/ml) made in tryptic soy broth (TSB) or TSB supplemented with 1% sucrose (TSBS; S. mutans) or yeast peptone dextrose broth (YPD; C. albicans). Suspensions of the nicotine-treated cells were prepared, mixed together and incubated for up to 24 hours to determine if there was an increase in coaggregation of nicotine-treated cells compared to the no nicotine control cells. Qualitative analysis of coaggregation was performed using a visual aggregation assay and light microscopic observation. A spectrophotometric assay was used to provide a quantitative analysis of the coaggregation. Results The visual aggregation assay indicated a significant increase in coaggregation between C. albicans and S. mutans with increasing incubation time (0 to 24 hours) and nicotine concentrations (0 to 4 mg/ml). Microbial growth in nicotine at 4 mg/ml demonstrated a significant increase in coaggregation after 24 hours of incubation. The numbers of coaggregated S. mutans/C. albicans cells exhibited a significant increase with incubation time and nicotine concentrations when the samples were examined microscopically. More coaggregation of S. mutans and C. albicans was observed with incubation time and increased nicotine compared to the 0 mg/ml nicotine group. There was a noticeable increase of coaggregation when cells were grown in TSBS compared to TSB. Absorbance of nicotine-treated cells (0.25 to 4 mg/ml) exhibited a decrease in values compared to 0 mg/ml at 0 hours of incubation, confirming increased coaggregation. Conclusion These results demonstrated the effect of nicotine in increasing the coaggregation of S. mutans with C. albicans. Coaggregation increased with incubation time and nicotine concentration. Coaggregation was increased with S. mutans grown in TSBS compared to TSB, suggesting that growth in sucrose media leads to an increase in receptors responsible for coaggregation.