Research Article

Characterization of dental pulp defect and repair in a canine model

 

Sibel  Yildirim, dds, phd,  Alp  Can, md, phd,  Mustafa  Arican, bvsc, phd,  Mildred  C.  Embree, dmd, phd &  Jeremy  J.  Mao, dds, phd

 

Abstract: Purpose: To explore a relationship between the size of pulp chamber perforation and reparative dentin formation in a canine model. Methods: Pulp defects were created in the pulp chambers of maxillary and mandibular premolars (N=64) in 17 healthy mongrel dogs in three different sizes (diameter/depth: 1/1, 2/1, and 2/2 mm³) with sterile round burs under general anesthesia. The perforations were immediately capped with hard-setting calcium hydroxide (CH) in the control group or sealed with Teflon membrane (TM) in the experimental group, followed by restoration with reinforced zinc oxide eugenol cement in vivo. Seven and 30 days after pulp chamber perforation and restoration all treated and control premolars were extracted and prepared for histomorphometric and statistical analyses. Results: Reparative dentin formation was more pronounced for defect sizes up to 2/1 mm³ when treated with CH, and completely bridged the surgically created dentin defects only after 30 days. However, reparative dentin upon CH treatment failed to completely bridge pulp chamber exposure for 2/2 defects. By contrast, TM treatment only yielded mild reparative dentin bridging for defects up to 1/1, but not for either 2/1 or 2/2 defects at 30 days. Inflammatory responses of the exposed dental pulp tissue were more robust with the TM group than with the CH group. Thus, dental pulp tissue possesses a capacity for spontaneous repair by the formation of reparative dentin in this preclinical model, but only up to a defect size of ~2 mm in diameter and 1 mm in depth. All observations are based on 30 days post-treatment in the canine model. These findings may serve as baseline for regenerative endodontic studies (Am J Dent 2011;24:331-335).

 

 

Mail: Dr. Jeremy J. Mao, Columbia University Medical Center, 630 W. 168 St. – PH7E – CDM, New York, NY 10032, USA. E-mail: jmao@columbia.edu

 

 

Research Article

Clinical evaluation of the fast onset and sustained sensitivity relief of a 0.454% stannous fluoride dentifrice compared to an 8.0% arginine-calcium carbonate-sodium monofluorophosphate dentifrice

 

Tao He, dds, phd, Jinlan Chang, bs, Richard Cheng, phd, Xin Li, bs, Lily Sun, ms  &  Aaron R. Biesbrock, dmd, phd

 

Abstract: Purpose: To evaluate the efficacy of a dentifrice containing 0.454% stannous fluoride (SnF₂) in the reduction of dentin hypersensitivity immediately after use, after 3 days and after a 2-week use period as compared to a positive control dentifrice containing 8.0% arginine, calcium carbonate and 1450 ppm fluoride as sodium monofluorophosphate. Methods: 80 healthy adult subjects with moderate dentin hypersensitivity were enrolled in this clinical study, which had a controlled, randomized, examiner-blind, two-treatment (40 subjects per treatment group), parallel group design. For each subject, two sensitive bicuspid or cuspid teeth in different quadrants demonstrating reproducible sensitivity to thermal stimuli (Schiff air sensitivity score of >1) were chosen for evaluation. Subjects were randomized to treatment with either the SnF₂ dentifrice or the positive control dentifrice. At the baseline visit, subjects were assessed for sensitivity to thermal stimuli, received an oral soft tissue examination, and were instructed to brush with their assigned dentifrice according to manufacturers’ usage instructions. Immediately after brushing, sensitivity to thermal stimuli for each enrolled tooth was assessed by an experienced dental examiner using the Schiff air sensitivity index and by study subjects based on air visual analog scale (VAS). After using their assigned dentifrice for 3 days and for 2 weeks, thermal sensitivity was re-assessed by both examiner and subject, and each subject received an oral soft tissue examination. Results: 40 subjects in the SnF₂ dentifrice group and 38 subjects in the control group completed all study procedures. Both dentifrice groups showed significant sensitivity relief relative to baseline (P< 0.01). The SnF₂ dentifrice provided a statistically significant (P= 0.005) 7.4% reduction in sensitivity relative to the positive control dentifrice immediately after first use and an even more significant (P= 0.001) 20% reduction at Week 2 based on the Schiff air sensitivity scale. Based on the VAS, the SnF₂ dentifrice provided statistically significant (P< 0.0001) reduction in sensitivity relative to the positive control dentifrice immediately after first use, at Day 3, and Week 2, with percent reductions of 7.2%, 15.8% and 28.2%, respectively. No adverse events were reported with either dentifrice. (Am J Dent 2011;24:336-340).

 

 

Mail: Dr. Tao He, Procter & Gamble Health Care Research Center, 8700 Mason-Montgomery Road, Mason, OH 45040, USA.  E-mail: he.t@pg.com

 

Research Article

Dielectrophoretic transport of fluoride into enamel

 

Chris  S.  Ivanoff, dds,  Timothy  L.  Hottel, dds, ms, mba,  Daranee  Versluis  Tantbirojn, dds, ms, phd, Antheunis  Versluis, phd  &  Franklin  GarcÍa-Godoy, dds, ms

 

Abstract: Purpose: To compare both quantitatively and qualitatively, the efficacy of dielectrophoresis to diffusion on the uptake of fluoride by enamel. Methods: A 1.23% APF gel was applied to 16 bovine incisor specimens for 20 minutes by dielectrophoresis or diffusion. Absorption and penetration were evaluated by wavelength dispersive spectrometry. Results: Fluoride concentrations in the diffusion group were significantly higher than baseline readings at 10 and 20 μm depths; fluoride concentration in dielectrophoretically treated teeth was significantly higher than the diffusion group at 10, 20, and 50 μm (ANOVA/Student-Newman-Keuls post hoc, P= 0.05). Significantly higher fluoride uptake was found with dielectrophoresis compared to passive diffusion at 10, 20, and 50 μm depths (paired t-test, P= 0.05). Dielectrophoresis doubled fluoride uptake in the superficial layers compared to passive diffusion, and drove the fluoride significantly deeper with an uptake six times higher than diffusion at 50 μm depth. Dielectrophoresis enhanced penetration and increased uptake of fluoride on average by 600% at 50 µm. The amount of fluoride delivered at 50 µm was equivalent to long-term exposure of prophylactic fluoride. With proper polarizing frequencies, dielectrophoresis could enhance fluoride delivery into tooth enamel at higher penetration depths and concentrations than diffusion. (Am J Dent 2011;24:341-345).

 

 

Mail: Dr. Chris S. Ivanoff, Department of Bioscience Research, College of Dentistry, University of Tennessee Health Science Center, 875 Union Avenue, Memphis, TN 38163, USA. E- mail: civanoff@uthsc.edu

 

 

Research Article

Microtensile bond strength of silorane-based resin composite and its corresponding adhesive in Class I occlusal restorations

 

Nantawan  Krajangta, bsc (med tech), dds  &  Sirivimol  Srisawasdi, dds, ms, phd

 

Abstract: Purpose: To determine the performance of a silorane-based resin composite, compared to that of a methacrylate-based resin composite, when used with their corresponding adhesive systems, and to determine the effects of c-factor and water storage time in Class I occlusal preparation, by means of microtensile bond strength (µTBS) test. Methods: Extracted human third molars were ground flat to expose dentin, and randomly divided into eight groups, according to the type of resin composite, c-factor, and water storage time: (1) Filtek P90/ high c-factor/24 hours, (2) Filtek P90/low c-factor/24 hours, (3) Filtek Z250/high c-factor/24 hours, (4) Filtek Z250/low c-factor/24 hours, (5), Filtek P90/ high c-factor/3 months, (6) Filtek P90/low c-factor/3 months, (7) Filtek Z250/high c-factor/3 months, and (8) Filtek Z250/ low c-factor/3 months. After 24 hours or 3 months of water storage, the bonded hourglass specimens were tested for µTBS, and failure types were also noted. Data were analyzed using three-way ANOVA and Tamhane post-hoc test (α = 0.05). Results: Filtek Z250/low c-factor/24 hours exhibited the highest µTBS (54.19 ± 9.05 MPa), and Filtek P90/high c-factor/3 months exhibited the lowest (6.94 ± 2.07 MPa).  All groups tested in high c-factor (> 4) preparations and 3-month water storage time showed significant decrease in µTBS, except when comparing between Filtek P90/high c-factor/24 hours and Filtek P90/high c-factor/3 months as there was no statistical difference. (Am J Dent 2011;24:346-353).

 

 

 

 

Mail: Dr. Sirivimol Srisawasdi, Department of Operative Dentistry, Faculty of Dentistry, Chulalongkorn University, Henri-Dunant Road, Bangkok 10330, Thailand.  E-mail: sirivimol6415@gmail.com

 

 

Research Article

Postoperative periodontal pain prevention using two dexamethasone medication protocols: A double-blind, parallel-group, placebo-controlled randomized clinical trial

 

Joao Paulo Steffens, dds, msc, Fábio AndrÉ Santos, dds, phd  &  Gibson Luiz Pilatti, dds, phd

 

Abstract: Purpose: To assess and compare the efficacy of two different dexamethasone protocols on pain prevention following periodontal surgery. Methods: 60 subjects presenting moderate to severe periodontitis with persisting clinical signs of inflammation after nonsurgical periodontal therapy on at least two adjacent teeth were scheduled for open flap debridement surgeries. This was a double-blind, parallel-group, placebo-controlled randomized clinical trial. Each patient was randomly assigned to receive one of the following preoperative medication protocols, 1 hour before surgery: Protocol 1 (P1): 4 mg dexamethasone, and another 4 mg 8 hours after the first dose; P2: 8 mg dexamethasone; P3: placebo. Pain intensity was evaluated hourly for the first 8 hours after surgery using the visual analogue scale (VAS). For ethical reasons, patients were instructed to use acetaminophen 750 mg as a rescue medication, only in case of pain. Results: P2 demonstrated to be more effective than P3 at all time periods, except for the 2nd hour. P2 was also superior to P1 at 1- (Kruskal-Wallis; P= 0.034), 5- (P= 0.03), 6- (P=0.04), 7- (P= 0.005) and 8-hour (P= 0.01) periods. The need for rescue medication was significantly prevented when P2 was used (ANOVA; P= 0.02). (Am J Dent 2011;24:354-356).

 

 

Mail: Prof. Dr. Gibson Luiz Pilatti, State University of Ponta Grossa – UEPG, Dentistry Post-Graduation Program, 4748 Carlos Cavalcanti Av. 84030-900 Ponta Grossa – PR – Brazil. E- mail: gibsonpilatti@gmail.com

 

 

Research Article

SEM evaluation of demineralized dentin treated with professional-strength NaF topical pastes

 

Robert  L.  Karlinsey, phd,  Allen  C.  Mackey, bs,  Craig  S.  Schwandt phd  &  Trenton  J.  Walker, bs

 

Abstract: Purpose: To qualitatively explore the effects of prescription-strength topical NaF pastes on patent tubules in a pH cycling model comprising remineralization and demineralization phases. Methods: 3 mm diameter dentin cores were extracted from bovine teeth, mounted in acrylic rods, ground and polished, and initially demineralized in 10 mL unstirred 50% citric acid (pH = 1.2) for 2 minutes to remove the smear layer and expose the dentin tubules. 72 acceptable specimens were then divided into six groups (12 per group) and subjected to a two-phase pH cycling study. The six pastes evaluated were as follows: fluoride-free Silly Strawberry, Clinpro 5000 and Clinpro Tooth Crème, MI Paste Plus, Sensodyne NUPRO 5000 and Topex Renew. First, the specimens were subjected to a remineralization regimen (Phase A), with each day comprising inverted immersion of specimens in three paste treatments (10 g paste: 20 mL distilled water) performed for 1 minute apiece with the immersion in artificial saliva (pH = 7.0) for 2 hours in between each treatment as well as overnight. After 7 days, the specimens were imaged using field emission scanning electron microscopy (FESEM). The remaining six specimens from each group were then cycled through a demineralization regimen (Phase B), with each day comprising inverted immersion of specimens in three rounds of a 1-minute treatment (10 g paste: 20 ml distilled water) followed immediately by a 3-minute static acid challenge (0.3% citric acid, pH = 3.8) with 2 hours in artificial saliva in between each round as well as overnight. After 3 days, the specimens were again imaged using FESEM. Results: After the Phase A regimen (i.e. remineralization phase), treatment with Silly Strawberry (fluoride-free), Sensodyne NUPRO 5000 and Topex Renew yielded qualitatively similar tubule pore appearance, whereby deposits appeared to have formed around the tubule openings. Clinpro 5000, MI Paste Plus and Clinpro Tooth Crème appeared to occlude dentin tubules as shown by the relatively smaller diameter tubule openings. Relative comparisons among these pastes revealed Clinpro 5000 appeared especially effective in narrowing and incorporating mineral within the tubule, while the MI Paste Plus and Clinpro Tooth Crème appear to produce comparable tubule occlusion. After the Phase B regimen (i.e. resistance to demineralization), qualitative comparisons revealed the fluoride-free, MI Paste Plus, NUPRO and Renew pastes did not appear to occlude dentin tubules as well as Clinpro 5000 and Clinpro Tooth Crème. (Am J Dent 2011;24:357-362).

 

 

Mail: Dr. Robert L. Karlinsey, Indiana Nanotech, 351 West 10th Street, Suite 309, Indianapolis, IN 46202, USA. E- mail:rkarlins@gmail.com

 

Research Article

Validity of caries-detection methods under epidemiological setting

 

Renato Pereira da Silva, dds, msc. phd, AndrÉa Videira Assaf, dds, msc. phd, Stela MÁrcia Pereira, dds, msc. phd, FÁbio Luiz  Mialhe, dds, msc. phd,  GlÁucia  Maria  Bovi  Ambrosano, agr eng, msc. phd, Marcelo de Castro Meneghim, dds, msc. phd  &  Antonio Carlos Pereira, dds, mph, drph

 

Abstract: Purpose: To evaluate the validity of the visual exam and adjunct diagnostic technologies for posterior permanent teeth under epidemiological conditions. Methods: A probabilistic sample of 165 12-year-old schoolchildren from Piracicaba, São Paulo, Brazil, was examined by visual exam (VI1), visual exam + artificial lighting (VI2), bitewing (BW), fiber optic transillumination (FOTI), DIAGNOdent and the associations among them. The D1+D3 and D3 diagnostics criteria, under epidemiological conditions, were adopted. The sensitivity, specificity and accuracy were calculated to determine the validity of the exams. Results: The most accurate diagnostic method was VI2+BW exam for all dental surfaces under both diagnostic criteria. It was concluded that the BW was the best adjunct diagnostic technology on epidemiological dental caries surveys, increasing the validity of the dental exams. (Am J Dent 2011;24:363-366).

 

 

Mail: Prof. Dr. Antonio Carlos Pereira, Department of Community Dentistry, Piracicaba Dental School – University of Campinas-UNICAMP, Av. Limeira 901, P.O. Box 52, CEP 13414-903, Piracicaba, São Paulo, Brazil. E- mail:  apereira@fop.unicamp.br

 

Research Article

Evaluation of marginal adaptation, seal and resistance against fatigue cracks of different pit and fissure sealants under laboratory load

 

Maria Teresa Rodriguez Tapia, dr med dent,  Stefano Ardu, phd, dr med dent,  Laurent Daeniker, dr med dent & Ivo Krejci, prof, dr med dent

 

Abstract: Purpose: To evaluate, in the laboratory, five light-cured pit and fissure sealants (ClinPro Sealant, Grandio Seal, Delton Seal-N-Go Illuminating, Embrace WetBond, Delton LC) and a filled bonding resin (Optibond FL Adhesive) used as a sealant in respect to their marginal adaptation before and after simultaneous thermal cycling and occlusal loading and their seal and failure cracks after loading. Methods: 60 caries-free upper molars were mechanically and thermally loaded after sealant application. Marginal adaptation was evaluated in the SEM before and after loading and a dye penetration test was performed after loading. In addition, micro-morphology of the occlusal contact area was qualitatively assessed. Results: Percentages of “continuous margin” ranged from 97.5 to 72.3% before, and from 92.2 to 56.6% after loading. Loading significantly influenced marginal quality (ANOVA, P< 0.05). Dye penetration after loading ranged from 0.05 to 1.21, with significant differences between groups (Kruskal-Wallis, P< 0.05). Different degrees of disintegration were observed in the occlusal contact area of all materials after loading. (Am J Dent 2011;24:367-371).

 

 

Mail: Prof. Dr. I. Krejci, Division of Cariology and Endodontology, School of Dentistry, University of Geneva 19, Rue Barthélemy-Menn, 1205 Geneva, Switzerland.  E-mail: ivo.krejci@unige.ch

 

Research Article

Fluoride release and recharge behavior of a nano-filled resin-modified glass ionomer compared with that of other fluoride releasing materials

 

Sumita  B.  Mitra, phd,  Joe  D.  Oxman, phd,  Afshin  Falsafi, phd  &   Tiffany  T.  Ton, bs

 

Abstract: Purpose: To compare the long-term fluoride release kinetics of a novel nano-filled two-paste resin-modified glass-ionomer (RMGI), Ketac Nano (KN) with that of two powder-liquid resin-modified glass-ionomers, Fuji II LC (FLC) and Vitremer (VT) and one conventional glass-ionomer, Fuji IX (FIX). Methods: Fluoride release was measured in vitro using ion-selective electrodes. Kinetic analysis was done using regression analysis and compared with existing models for GIs and compomers. In a separate experiment the samples of KN and two conventional glass-ionomers, FIX and Ketac Molar (KM) were subjected to a treatment with external fluoride source (Oral-B Neutra-Foam) after 3 months of fluoride release and the recharge behavior studied for an additional 7-day period. Results: The cumulative amount of fluoride released from KN, VT and FLC and the release profiles were statistically similar but greater than that for FIX at P< 0.05. All four materials, including KN, showed a burst of fluoride ions at shorter times (t) and an overall rate dependence on t_1/2 typical for glass-ionomers. The coating of KN with its primer and of DY with its adhesive did not significantly alter the fluoride release behavior of the respective materials. The overall rate for KN was significantly higher than for the compomer DY. DY showed a linear rate of release vs. t and no burst effect as expected for compomers. The nanoionomer KN showed fluoride recharge behavior similar to the conventional glass ionomers FIX and KM. Thus, it was concluded that the new RMGI KN exhibits fluoride ion release behavior similar to typical conventional and RMGIs and that the primer does not impede the release of fluoride. (Am J Dent 2011;24:372-378).

 

 

 

 

 

Mail: Dr. Sumita B. Mitra, Partner, Mitra Chemical Consulting LLC, 1952 Nature View Lane, West St. Paul, MN 55118, USA.  E- mail: sumitabmitra@gmail.com

 

Research Article

Pharmacokinetics and clinical efficacy of delmopinol in an open rinse time study in healthy volunteers

 

Torgny SjÖdin, phd, Jan HÅkansson, phd, Birgitta Sparre, bsc, Inger Ekman, msc pharm  &  Mikael ÅstrÖm, phl

 

Abstract: Purpose: To compare three different rinse times with delmopinol (15, 30 and 60 seconds) with respect to inhibition of plaque growth and to determine the pharmacokinetic parameters of delmopinol for these rinse times. Methods: This open and randomized study with a cross-over design was performed in healthy male volunteers and consisted of four treatment periods of 1 week separated by washout periods of at least 6 days. The first test period started with staining of the teeth followed by planimetric recordings before and after professional cleaning. Adverse records were also obtained. The volunteers, randomly assigned to a rinsing time sequence, were instructed to cease all oral hygiene measures except for the mouthrinse with placebo or delmopinol solutions. The rinses were performed without supervision twice daily for 7 days for each rinsing time. On Day 7, plaque % index and planimetric registrations were obtained, adverse effects recorded and the teeth were cleaned professionally. Plasma samples for the pharmacokinetic evaluation were also taken. The remaining test periods were performed in the same way, except that no baseline planimetric recordings were made. During the washout periods the volunteers returned to their normal oral hygiene behavior. Venous blood samples were drawn from all volunteers into sodium heparin-containing tubes. Results: A significant time-response was obtained with respect to the planimetric results. The mean areas of the teeth covered with plaque after the test periods (placebo, 15, 30 and 60 seconds) were 41%, 29%, 23% and 18%, respectively. Statistical analysis showed that rinsing with delmopinol for 30 or 60 seconds differed significantly (P< 0.05) from placebo. There was also a significant difference between rinsing for 15 and 60 seconds. From the plaque % index data it was found that all three rinsing times differed significantly from placebo. However, between the three rinse times with active solution, no significant difference in plaque % index occurred. Statistical analysis of the systemic exposure, in terms of the pharmacokinetic parameters AUC_12h and C_max showed a significant treatment effect. The exposure increased with increasing rinse time, although the increase (AUC_12h and C_max) was less than proportional to the rinse time. (Am J Dent 2011;24:383-388).

 

 

 

 

Mail:  Dr. Torgny Sjödin, Sinclair Pharma AB, Ekonomivägen 5, SE-436 33 Askim, Sweden. E- mail:  tsjodin@sinclairpharma.com