Department of Prosthodontics

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Effect of different endodontic regeneration protocols on wettability, roughness and chemical composition of surface dentin
(Elsevier, 2015-06) Yassen, Ghaeth H.; Sabrah, Alaa H. A.; Eckert, George J.; Platt, Jeffrey A.; Department of Restorative Dentistry, IU School of Dentistry
Introduction We investigated the changes in physiochemical properties of dentin surfaces after performing different endodontic regeneration protocols. Methods Human dentin slices were randomized into 4 treatment groups and 1 untreated control group (n = 10). One treatment group was irrigated with sodium hypochlorite (NaOCl) for 5 minutes followed by EDTA for 10 minutes. The other 3 treatment groups were irrigated with NaOCl; treated for 4 weeks with triple antibiotic paste (TAP), diluted triple antibiotic paste (DTAP), or calcium hydroxide (Ca[OH]2); and then irrigated with EDTA. After treatment, contact angles between a blood analog and dentin surfaces were evaluated. Surface roughness and chemical composition were characterized using optical profilometry and energy-dispersive X-ray spectroscopy, respectively. One-way analysis of variance followed by Fisher least significant difference tests were used for statistical analyses. Results All treatment groups showed a significant reduction in wettability and a significant increase in surface roughness when compared with untreated dentin. Dentin treated with Ca(OH)2 had significantly lower wettability compared with all other groups. No significant difference in wettability was found between dentin treated with DTAP and TAP protocols. Dentin treated with TAP had significantly higher surface roughness compared with all other groups. Untreated dentin and NaOCl + EDTA–treated dentin had significantly higher calcium and phosphorus as well as significantly lower carbon compared with dentin treated with Ca(OH)2, DTAP, and TAP. Conclusions Endodontic regeneration protocols had a significant effect on wettability, surface roughness, and chemical composition of surface dentin. The Ca(OH)2 protocol caused a significant reduction in dentin wettability compared with TAP or DTAP protocols.
The Effect of Diluted Triple and Double Antibiotic Pastes on Dental Pulp Stem Cells and Established Enterococcus faecalis Biofilm
(Springer, 2015-11) Sabrah, Alaa H. A.; Yassen, Ghaeth H.; Liu, Wai-Ching; Goebel, W. Scott; Gregory, Richard L.; Platt, Jeffrey A.; Department of Restorative Dentistry, IU School of Dentistry
Objectives To investigate the effect of various dilutions of antibiotic medicaments used in endodontic regeneration on the survival of human dental pulp stem cells (DPSCs) and to determine their antibacterial effect against established Enterococcus faecalis biofilm. Materials and methods The cytotoxic and antibacterial effects of different triple (TAP) and double antibiotic paste (DAP) dilutions (0.125, 0.25, 0.5, 1, and 10 mg/ml) were tested against Enterococcus faecalis established biofilm and DPSC. Established bacterial biofilm were exposed to antibiotic dilutions for 3 days. Then, biofilms were collected, spiral plated, and the numbers of bacterial colony forming units (CFU/ml) were determined. For the cytotoxic effect, lactate dehydrogenase activity assays (LDH) and cell viability assays (WST-1) were used to measure the percentage of DPSC cytotoxicity after 3-day treatment with the same antibiotic dilutions. A general linear mixed model was used for statistical analyses (α = 0.05). Results All antibiotic dilutions significantly decreased the bacterial CFU/ml. For WST-1 assays, all antibiotic dilutions except 0.125 mg/ml significantly reduced the viability of DPSC. For LDH assays, the three lowest tested concentrations of DAP (0.5, 0.25, 0.125 mg/ml) and the two lowest concentrations of TAP (0.25 and 0.125 mg/ml) were non-toxic to DPSC. Conclusions All tested dilutions had an antibacterial effect against E. faecalis. However, 0.125 mg/ml of DAP and TAP showed a significant antibacterial effect with no cytotoxic effects on DPSCs. Clinical relevance Using appropriate antibiotic concentrations of intracanal medicament during endodontic regeneration procedures is critical to disinfect root canal and decrease the adverse effects on stem cells.
The use of traditional and novel techniques to determine the hardness and indentation properties of immature radicular dentin treated with antibiotic medicaments followed by ethylenediaminetetraacetic acid
(Wolters Kluwer, 2014-10) Yassen, Ghaeth H.; Al‑Angari, Sarah S.; Platt, Jeffrey; Department of Restorative Dentistry, School of Dentistry
OBJECTIVE: The objective was to investigate the effect of intracanal antibiotic medicaments followed by ethylenediaminetetraacetic acid (EDTA) on the indentation properties and hardness of radicular dentin using a BioDent reference point indenter and a traditional microhardness technique, respectively. MATERIALS AND METHODS: Specimens with intact root canal dentin surfaces and polished radicular dentin specimens were obtained from immature human premolars. Each type of specimen was randomly assigned (n = 10 per group) and treated with either double antibiotic paste (DAP) for 4-week followed by EDTA for 5 min, triple antibiotic paste (TAP) for 4-week followed by EDTA for 5 min, EDTA for 5 min or Hank's balanced salt solution (control). The BioDent reference point indentor and Vickers microhardness tester were used to measure the indentation properties of root canal surfaces and the hardness of polished dentin specimens, respectively. One-way ANOVA followed by Fisher's protected least significant differences were used for statistical analyses. RESULTS: Both types of radicular dentin treated with antibiotic pastes and/or EDTA had a significant increase in the majority of indentation properties and a significant reduction in hardness compared to the untreated dentin. Furthermore, treatment of dentin with antibiotic pastes and EDTA caused significant increases in indentation properties and a significant reduction in hardness compared to EDTA-treated dentin. However, the RPI technique was not able to significantly differentiate between DAP + EDTA and TAP + EDTA-treated dentin. CONCLUSION: Dentin treated with antibiotic medicaments followed by EDTA had a significant increase the indentation properties and significantly reduction in hardness of radicular dentin.
Effect of intracanal medicaments used in endodontic regeneration procedures on microhardness and chemical structure of dentin
(Synapse, 2015-05) Hamdon, Ghaeth Yassen; George, Joseph Eckert; Platt, Jeffrey Allen; Department of Restorative Dentistry, School of Dentistry
OBJECTIVES: This study was performed to investigate the effects of different intracanal medicaments on chemical structure and microhardness of dentin. MATERIALS AND METHODS: Fifty human dentin discs were obtained from intact third molars and randomly assigned into two control groups and three treatment groups. The first control group received no treatment. The second control group (no medicament group) was irrigated with sodium hypochlorite (NaOCl), stored in humid environment for four weeks and then irrigated with ethylenediaminetetraacetic acid (EDTA). The three treatment groups were irrigated with NaOCl, treated for four weeks with either 1 g/mL triple antibiotic paste (TAP), 1 mg/mL methylcellulose-based triple antibiotic paste (DTAP), or calcium hydroxide [Ca(OH)2] and finally irrigated with EDTA. After treatment, one half of each dentin disc was subjected to Vickers microhardness (n = 10 per group) and the other half was used to evaluate the chemical structure (phosphate/amide I ratio) of treated dentin utilizing attenuated total reflection Fourier transform infrared spectroscopy (n = 5 per group). One-way ANOVA followed by Fisher's least significant difference were used for statistical analyses. RESULTS: Dentin discs treated with different intracanal medicaments and those treated with NaOCl + EDTA showed significant reduction in microhardness (p < 0.0001) and phosphate/amide I ratio (p < 0.05) compared to no treatment control dentin. Furthermore, dentin discs treated with TAP had significantly lower microhardness (p < 0.0001) and phosphate/amide I ratio (p < 0.0001) compared to all other groups. CONCLUSIONS: The use of DTAP or Ca(OH)2 medicaments during endodontic regeneration may cause significantly less microhardness reduction and superficial demineralization of dentin compared to the use of TAP.
Utilizing Dental Electronic Health Records Data to Predict Risk for Periodontal Disease
(IOS, 2015) Thyvalikakath, Thankam P.; Padman, Rema; Vyawahare, Karnali; Darade, Pratiksha; Paranjape, Rhucha; Department of Restorative Dentistry, IU School of Dentistry
Periodontal disease is a major cause for tooth loss and adversely affects individuals' oral health and quality of life. Research shows its potential association with systemic diseases like diabetes and cardiovascular disease, and social habits such as smoking. This study explores mining potential risk factors from dental electronic health records to predict and display patients' contextualized risk for periodontal disease. We retrieved relevant risk factors from structured and unstructured data on 2,370 patients who underwent comprehensive oral examinations at the Indiana University School of Dentistry, Indianapolis, IN, USA. Predicting overall risk and displaying relationships between risk factors and their influence on the patient's oral and general health can be a powerful educational and disease management tool for patients and clinicians at the point of care.
Bimix antimicrobial scaffolds for regenerative endodontics
(Elsevier, 2014-11) Palasuk, Jadesada; Kamocki, Krzysztof; Hippenmeyer, Lauren; Platt, Jeffrey A.; Spolnik, Kenneth J.; Gregory, Richard L.; Bottino, Marco C.; Department of Restorative Dentistry, IU School of Dentistry
INTRODUCTION: Eliminating and/or inhibiting bacterial growth within the root canal system has been shown to play a key role in the regenerative outcome. The aim of this study was to synthesize and determine in vitro both the antimicrobial effectiveness and cytocompatibility of bimix antibiotic-containing polydioxanone-based polymer scaffolds. METHODS: Antibiotic-containing (metronidazole [MET] and ciprofloxacin [CIP]) polymer solutions (distinct antibiotic weight ratios) were spun into fibers as a potential mimic to the double antibiotic paste (DAP, a MET/CIP mixture). Fiber morphology, chemical characteristics, and tensile strength were evaluated by scanning electron microscopy, Fourier transform infrared spectroscopy, and tensile testing, respectively. Antimicrobial efficacy was tested over time (aliquot collection) against Enterococcus faecalis (Ef), Porphyromonas gingivalis (Pg), and Fusobacterium nucleatum (Fn). Similarly, cytotoxicity was evaluated in human dental pulp stem cells. Data were statistically analyzed (P < .05). RESULTS: Scanning electron microscopy and Fourier transform infrared spectroscopy confirmed that electrospinning was able to produce antibiotic-containing fibers with a diameter mostly in the nanoscale. The tensile strength of 1:1MET/CIP scaffolds was significantly (P < .05) higher than pure polydioxanone (control). Meanwhile, all other groups presented similar strength as the control. Aliquots obtained from antibiotic-containing scaffolds inhibited the growth of Ef, Pg, and Fn, except pure MET, which did not show an inhibitory action toward Pg or Fn. Antibiotic-containing aliquots promoted slight human dental pulp stem cell viability reduction, but none of them were considered to be cytotoxic. CONCLUSIONS: Our data suggest that the incorporation of multiple antibiotics within a nanofibrous scaffold holds great potential toward the development of a drug delivery system for regenerative endodontics.
Monitoring of sound and carious surfaces under sealants over 44 months
(SAGE Publications, 2014-11) Fontana, M.; Platt, J. A.; Eckert, G. J.; González-Cabezas, C.; Yoder, K.; Zero, D. T.; Ando, M.; Soto-Rojas, A. E.; Peters, M. C.; Department of Restorative Dentistry, IU School of Dentistry
Although there is strong evidence for the effectiveness of sealants, one major barrier in sealant utilization is the concern of sealing over active caries lesions. This study evaluated detection and monitoring of caries lesions through a clear sealant over 44 mo. Sixty-four 7- to 10-year-old children with at least 2 permanent molars with International Caries Detection and Assessment System (ICDAS) scores 0-4 (and caries less than halfway through the dentin, radiographically) were examined with ICDAS, DIAGNOdent, and quantitative light-induced fluorescence (QLF) before sealant placement and 1, 12, 24, and 44 mo (except QLF) after. Bitewing radiographs were taken yearly. DIAGNOdent and QLF were able to distinguish between baseline ICDAS before and after sealant placement. There was no significant evidence of ICDAS progression at 12 mo, but there was small evidence of minor increases at 24 and 44 mo (14% and 14%, respectively) with only 2% ICDAS ≥ 5. Additionally, there was little evidence of radiographic progression (at 12 mo = 1%, 24 mo = 3%, and 44 mo = 9%). Sealant retention rates were excellent at 12 mo = 89%, 24 mo = 78%, and 44 mo = 70%. The small risk of sealant repair increased significantly as baseline ICDAS, DIAGNOdent, and QLF values increased. However, regardless of lesion severity, sealants were 100% effective at 12 mo and 98% effective over 44 mo in managing occlusal surfaces at ICDAS 0-4 (i.e., only 4 of 228 teeth progressed to ICDAS ≥ 5 associated with sealants in need of repair and none to halfway or more through the dentin, radiographically). This study suggests that occlusal surfaces without frank cavitation (ICDAS 0-4) that are sealed with a clear sealant can be monitored with ICDAS, QLF, or DIAGNOdent, which may aid in predicting the need for sealant repair.
Biodegradable nanofibrous drug delivery systems: effects of metronidazole and ciprofloxacin on periodontopathogens and commensal oral bacteria
(Springer-Verlag, 2014-12) Bottino, Marco C.; Arthur, Rodrigo A.; Waeiss, R. Aaron; Kamocki, Krzysztof; Gregson, Karen S.; Gregory, Richard L.; Department of Restorative Dentistry, IU School of Dentistry
OBJECTIVES: The purposes of this study were to fabricate biodegradable polydioxanone (PDS II®) electrospun periodontal drug delivery systems (hereafter referred to as matrices) containing either metronidazole (MET) or ciprofloxacin (CIP) and to investigate the effects of antibiotic incorporation on both periodontopathogens and commensal oral bacteria. MATERIALS AND METHODS: Fibrous matrices were processed from PDS polymer solution by electrospinning. Antibiotic-containing PDS solutions were prepared to obtain four distinct groups: 5 wt.% MET, 25 wt.% MET, 5 wt.% CIP, and 25 wt.% CIP. Pure PDS was used as a control. High-performance liquid chromatography (HPLC) was done to evaluate MET and CIP release. Dual-species biofilms formed by Lactobacillus casei (Lc) and Streptococcus salivarius (Ss) were grown on the surface of all electrospun matrices. After 4 days of biofilm growth, the viability of bacteria on biofilms was assessed. Additionally, antimicrobial properties were evaluated against periodontopathogens Fusobacterium nucleatum (Fn) and Aggregatibacter actinomycetemcomitans (Aa) using agar diffusion assay. RESULTS: A three-dimensional interconnected porous network was observed in the different fabricated matrices. Pure PDS showed the highest fiber diameter mean (1,158 ± 402 nm) followed in a descending order by groups 5 wt.% MET (1,108 ± 383 nm), 25 wt.% MET (944 ± 392 nm), 5 wt.% CIP (871 ± 309 nm), and 25 wt.% CIP (765 ± 288 nm). HPLC demonstrated that groups containing higher amounts (25 wt.%) of incorporated drugs released more over time, while those with lower levels (5 wt.%) the least. No inhibitory effect of the tested antibiotics was detected on biofilm formation by the tested commensal oral bacteria. Meanwhile, CIP-containing matrices inhibited growth of Fn and Aa. CONCLUSION: CIP-containing matrices led to a significant inhibition of periodontopathogens without negatively impairing the growth of periodontal beneficial bacteria. CLINICAL RELEVANCE: Based on the proven in vitro inhibition of periodontitis-related bacteria, future in vivo research using relevant animal models is needed to confirm the effectiveness of these drug delivery systems.
Physicomechanical properties of a zinc-reinforced glass ionomer restorative material
(2014) Al-Angari, Sarah S.; Hara, Anderson T.; Chu, Tien-Min; Platt, Jeffrey; Eckert, George; Cook, N. Blaine; Department of Restorative Dentistry, School of Dentistry
We compared a zinc-reinforced glass ionomer restorative material (ChemFil Rock) with three commercially available glass ionomer cements (GICs), namely, Fuji IX GP Extra, Ketac Molar Quick Aplicap, and EQUIA Fil, with respect to fracture toughness, microhardness, roughness, and abrasive wear. Fracture toughness (KIC) was tested according to ISO 13586 (n = 10). Hardness, roughness, and abrasive wear were also tested (n = 9). Data were analyzed using the Wilcoxon rank-sum test with adjustment for multiple comparisons (α = 0.05). As compared with the other GICs ChemFil Rock exhibited a greater increase in surface roughness (P < 0.05) and lower microhardness (P < 0.01). The wear resistance of ChemFil Rock was comparable to that of the other GICs (P > 0.05). ChemFil Rock had significantly lower fracture toughness as compared with EQUIA Fil (P = 0.01) and significantly higher fracture toughness as compared with the other GICs (P < 0.02). In conclusion, as compared with the three other commercially available GICs, ChemFil Rock had intermediate fracture toughness, the lowest microhardness, and the greatest change in surface roughness.
Influence of Light Intensity on Surface Free Energy and Dentin Bond Strength of Core Build-up Resins
(Academy of Operative Dentistry, 2015-01) Shimizu, Yuske; Tsujimoto, Akimasa; Furuichi, Tetsuya; Suzuki, Takayuki; Tsubota, Keishi; Miyazaki, Masashi; Platt, Jeffrey A.; Department of Restorative Dentistry, IU School of Dentistry
Objective: We examined the influence of light intensity on surface free energy characteristics and dentin bond strength of dual-cure direct core build-up resin systems. Methods: Two commercially available dual-cure direct core build-up resin systems, Clearfil DC Core Automix with Clearfil Bond SE One and UniFil Core EM with Self-Etching Bond, were studied. Bovine mandibular incisors were mounted in acrylic resin and the facial dentin surfaces were wet ground on 600-grit silicon carbide paper. Adhesives were applied to dentin surfaces and cured with light intensities of 0 (no irradiation), 200, 400, and 600 mW/cm2. The surface free energy of the adhesives (five samples per group) was determined by measuring the contact angles of three test liquids placed on the cured adhesives. To determine the strength of the dentin bond, the core build-up resin pastes were condensed into the mold on the adhesive-treated dentin surfaces according to the methods described for the surface free energy measurement. The resin pastes were cured with the same light intensities as those used for the adhesives. Ten specimens per group were stored in water maintained at 37°C for 24 hours, after which they were shear tested at a crosshead speed of 1.0 mm/minute in a universal testing machine. Two-way analysis of variance (ANOVA) and a Tukey-Kramer test were performed, with the significance level set at 0.05. Results: The surface free energies of the adhesive-treated dentin surfaces decreased with an increase in the light intensity of the curing unit. Two-way ANOVA revealed that the type of core build-up system and the light intensity significantly influence the bond strength, although there was no significant interaction between the two factors. The highest bond strengths were achieved when the resin pastes were cured with the strongest light intensity for all the core build-up systems. When polymerized with a light intensity of 200 mW/cm2 or less, significantly lower bond strengths were observed. Conclusions: The data suggest that the dentin bond strength of core build-up systems are still affected by the light intensity of the curing unit, which is based on the surface free energy of the adhesives. On the basis of the results and limitations of the test conditions used in this study, it appears that a light intensity of >400 mW/cm2 may be required for achieving the optimal dentin bond strength.

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