Influence of Trigonella foenum graecum seed extract as root canal irrigation agent on root surfaces: A scanning electron microscope/energy dispersive X-ray analysis study.

The purpose of this in vitro study was to investigate the effect of Trigonella foenum graecum seed extract (TFGSE) as a root canal irrigation agent on the surface of instrumented root canals and on changes in the mineral contents of the root dentin. A total of 90 extracted human mature maxillary central incisor teeth with a single root and without root resorption were selected. The specimens were subdivided into five groups according to irrigation protocol groups G0: distilled water (n = 15): G1: Sodium hypochlorite (5.25% NaOCl); G2: 1% TFGSE G3: NaOCl +17% EDTA (3 min); G4: NaOCl+1% TFGSE; G5: 1% TFGSE +17% EDTA. All the roots were sectioned longitudinally into two halves and examined under scanning electron microscope/energy dispersive X-ray analysis (SEM/EDX) to assess changes in the mineral content of the tooth. Smear layer removal from root canals was evaluated with scanning electron microscopy (SEM). A statistical analysis was performed using the Kruskal-Wallis test. The most effective irrigation protocols in removing smear layer occurred with TFGSE and NaOCl, both with rinsing with 17% EDTA. TFGSE was more effective than NaOCl for removing the smear layer. The results showed the ability of 1% TFGSE to remove the smear layer from the root canals. TFGSE is a promising alternative irrigation agent for root canals.

Microsphere controlled drug delivery for local control of tooth movement.

Background: Because orthodontic tooth movement is dependent upon osteoclast-mediated resorption of alveolar bone adjacent to the pressure side of tooth roots, biologic mediators that regulate osteoclasts can be utilized to control tooth movement. Objectives: To develop a novel method to locally enhance orthodontic anchorage. Methods: We encapsulated osteoprotegerin (OPG) in polymer microspheres and tested the effectiveness of microsphere encapsulated versus non-encapsulated OPG for enhancing orthodontic anchorage in a rodent model of tooth movement. A single injection of 1 mg/kg non-encapsulated or microsphere encapsulated OPG was delivered into the palatal mucosa mesial to the first maxillary molar 1 day prior to tooth movement. A positive control group received injections of 5 mg/kg non-encapsulated OPG every 3 days during tooth movement. After 28 days of tooth movement, hemi-maxillae and femurs were dissected. Molar mesial and incisor distal tooth movement was measured using stone casts that were scanned and magnified. Local alveolar, distant femur bone, and tooth root volumes were analyzed by micro computed tomography. Serum OPG levels were measured by ELISA. Osteoclast numbers were quantified by histomorphometry. Results: The single injection of microsphere encapsulated OPG significantly enhanced orthodontic anchorage, while the single injection of non-encapsulated OPG did not. Injection of encapsulated OPG inhibited molar mesial movement but did not inhibit incisor tooth movement, and did not alter alveolar or femur bone volume fraction, density, or mineral content. Multiple injections of 5 mg/kg non-encapsulated OPG enhanced orthodontic anchorage, but also inhibited incisor retraction and altered alveolar and femur bone quality parameters. Increased OPG levels were found only in animals receiving multiple injections of non-encapsulated 5 mg/kg OPG. Osteoclast numbers were higher upon tooth movement in animals that did not receive OPG. Osteoclast numbers in OPG injected animals were variable within groups. Conclusions: Microsphere encapsulation of OPG allows for controlled drug release, and enhances site-specific orthodontic anchorage without systemic side effects. With additional refinements, this drug delivery system could be applicable to a broad array of potential biologic orthodontic therapeutics.

Negative effects of retinoic acid on stem cell niche of mouse incisor.

The continuous growth of mouse incisors depends on epithelial stem cells (SCs) residing in the SC niche, called labial cervical loop (LaCL). The homeostasis of the SCs is subtly regulated by complex signaling networks. In this study, we focus on retinoic acid (RA), a derivative of Vitamin A and a known pivotal signaling molecule in controlling the functions of stem cells (SCs). We analyzed the expression profiles of several key molecules of the RA signaling pathway in cultured incisor explants upon exogenous RA treatment. The expression patterns of these molecules suggested a negative feedback regulation of RA signaling in the developing incisor. We demonstrated that exogenous RA had negative effects on incisor SCs and that this was accompanied by downregulation of Fgf10, a mesenchymally expressed SC survival factor in the mouse incisor. Supplement of Fgf10 in incisor cultures completely blocked RA effects by antagonizing apoptosis and increasing proliferation in LaCL epithelial SCs. In addition, Fgf10 obviously antagonized RA-induced downregulation of the SC marker Sox2 in incisor epithelial SCs. Our findings suggest that the negative effects of RA on incisor SCs result from inhibition of mesenchymal Fgf10.

Regenerative Endodontic Treatment versus Apical Plug in Immature Teeth: Three-Year Follow-Up.

This report compares and evaluates the treatment outcomes of regenerative endodontic treatment and apical plug as two accepted treatment protocols in a pair of necrotic immature maxillary central incisors of a 12-year old female. The patient was referred complaining of a dull pain and swelling in her upper lip area. She had a history of trauma to the anterior maxilla two years earlier. Both teeth were clinically diagnosed with pulp necrosis and periapical radiographs revealed that separate periapical radiolucent lesions surrounded the immature apices of both teeth. The left and right incisors were treated with apical plug and regenerative endodontic treatment, respectively, using calcium-enriched mixture (CEM) cement. The patient was followed-up for three years. During this period, both teeth were clinically asymptomatic and showed complete radiographic healing of the periapical lesions. The right central incisor showed root development. No tooth discoloration was evident. Apexification by apical plug placement and pulp regeneration are both reliable treatments for immature non-vital teeth. In order to choose the right treatment the advantages of either technique should be weighed against its drawbacks. CEM cement can be successfully applied for both purposes. This biomaterial causes less discoloration of the tooth.

Prenatally administered HMB modifies the enamel surface roughness in spiny mice offspring: An atomic force microscopy study.

OBJECTIVE: The aim of this research was to check the effect of the prenatally administered ß-hydroxy ß-methylbutyrate (HMB) on the development of enamel surface of the spiny mice offspring. DESIGN: The spiny mice dams were randomly assigned into three groups: control group (not supplemented with HMB) and two experimental groups in which powdered HMB was given at the daily dosage of 0.2g/kg of body weight (group I) and 0.02g/kg of body weight (group II) during the last period of gestation. Newborn pups were euthanized by CO2 inhalation. The morphology of incisor teeth was analysed using atomic force microscopy (AFM) in semi-contact mode in the height, magnitude and phase domains. Height images became a basis for determination of surface roughness parameters. RESULTS: Conducted study indicated that maternal HMB administration markedly influences enamel development. Enamel of offspring's teeth in both experimental groups was characterized by significantly smaller values of indices describing surface roughness and profile. HMB supplementation influenced the calculated parameters regardless of the diet type and offspring sex, however higher dose of HMB caused stronger changes in enamel surface's physical properties and could be observed in higher intensity in the male group. CONCLUSIONS: HMB administration caused reduction in the irregularities of enamel surface, thereby possibly reducing the probability of bacteria adhesion and caries development. These observations may serve to improve nutrition and supplementation of animals and could be a lead for further research.

Comparative Evaluation of Mental Incisal Nerve Block, Inferior Alveolar Nerve Block, and Their Combination on the Anesthetic Success Rate in Symptomatic Mandibular Premolars: A Randomized Double-blind Clinical Trial.

INTRODUCTION: The purpose of this study was to compare the effectiveness of mental incisive nerve block (MINB) and inferior alveolar nerve block (IANB) that were given alone or in combination to provide anesthesia to symptomatic mandibular premolars. METHODS: One hundred fifty-three patients participated in this randomized, double-blind clinical trial. The patients were divided into 3 groups; first group received MINB with 2 mL 2% lidocaine with 1:200,000 epinephrine and a mock IANB with 2 mL sterile saline, patients in group 2 received mock MINB and an IANB with 2 mL 2% lidocaine, and patients in group 3 received both MINB and IANB with 2 mL each of 2% lidocaine. Access cavity preparation was initiated after 10 minutes. Success was defined as no pain or faint/weak/mild pain during endodontic access preparation and instrumentation. The anesthetic success rates were analyzed with Pearson χ(2) test at 5% significance levels. RESULTS: The MINB and IANB gave 53% and 47% anesthetic success rates, respectively, with no significant difference between them. Adding an IANB to MINB significantly improved the success rates to 82%. CONCLUSIONS: A combination of MINB and IANB can provide improved local anesthesia for symptomatic mandibular premolars.

Sodium Thiosulfate for Recovery of Bond Strength to Dentin Treated with Sodium Hypochlorite.

INTRODUCTION: The aim of this study was to evaluate the efficacy of sodium thiosulfate (Na2S2O3) for restoring adhesion to pulp chamber dentin treated with sodium hypochlorite (NaOCl) and EDTA. METHODS: Sixty-three crowns of bovine incisors were cut to expose the dentin pulp chamber. The specimens were polished and randomly distributed into 9 groups (n = 7) according to the following protocols used: 0.9% sodium chloride for 30 minutes (negative control), 5.25% NaOCl for 30 minutes, 17% EDTA for 3 minutes, and 5.25% NaOCl for 1 minute (positive control). The other groups, after treatments with NaOCl and EDTA, were immersed in 0.5% or 5% Na2S2O3 for 1, 5, and 10 minutes or just immersed in an inert solution for 10 minutes (0.9% sodium chloride). After drying the specimens, Scotchbond Multi-Purpose (3M ESPE, St Paul, MN) was applied to the pulp chamber dentin followed by Filtek Z250 composite (3M ESPE). Six rectangular slabs were obtained from each specimen, and the dentin/resin interface was tested by using a universal testing machine. The resulting data were submitted to 1-way analysis of variance and the Duncan test (P = .05). RESULTS: There was a significant decrease in bond strength regarding NaOCl and EDTA (P < .05). When 5% Na2S2O3 was used for 10 minutes, the bond strength was found to be statistically equal to the negative control and higher than the positive control (P < .05). CONCLUSIONS: The use of Na2S2O3 can significantly increase the bond strength of composite resin to NaOCl/EDTA-treated dentin, allowing adhesive restorations to be immediately applied after endodontic treatment.

Revascularization Induced Maturogenesis of Non-Vital Immature Permanent Tooth Using Platelet-Rich-Fibrin: A Case Report.

The aim of this report is to describe a novel method of revascularization therapy done in a non-vital, immature permanent tooth using Platelet-rich fibrin (PRF),in a recently developed scaffold material to overcome limitations associated with the traditional method of revascularization using natural blood clot. PRF prepared from autologous blood was placed in the root canal and patient was followed up regularly at one, three, six, nine and 12 months for detailed clinical and radiographic evaluation. At 12 months, radiographic examination revealed root elongation, root end closure, continued thickening of the root dentinal walls, obliteration of root canal space, and normal periradicular anatomy. However, more long term prospective trials and histological studies are highly needed before to testify PRF a panacea for the regenerative endodontic therapy in children.

Extrinsic tooth staining potential of high dose and sustained release iron syrups on primary teeth.

BACKGROUND: Iron in the form of oral supplements is routinely prescribed to children to help fight anemia, however tooth staining is a commonly reported complication. This study tests in vitro, the staining potential of two different forms of iron syrup on primary teeth. METHODS: Forty caries free primary central incisors were divided into four groups of ten teeth each. The control group comprised of ten teeth immersed in artificial saliva, while the test solutions were comprised of different forms of iron mixed with vitamins such that the iron content of each solution was approximately 100 mg (from 100 to 101.1 mg). The test solutions used iron syrup (Ferrose®, SPIMACO, Jeddah, Saudi Arabia) with iron in the form of ferric oxide polymaltose (FOP), slow release formula (Ferroglobin®, Vitabiotics ltd., London, UK) containing ferrous fumarate (FF and a combination of the two (FOP + FF). All the teeth were then immersed for 72 h and subjected to a protocol developed by Lee et al. to test staining. Color changes were measured using a wave dispersion spectro-photometer (Color-Eye 7000A, X-Rite Gmbh, Regensdorf, Switzerland) on the exposed labial surface at 4, 8, 24, 48 and 72 h. Two-way ANOVA with Scheffe's post hoc test was used to determine significance of difference in shade, while the Kurskull-Wallis test used to determine the significance of difference in clinical staining (∆E > 3). RESULTS: While all three iron groups showed some amount of staining, the combination of the two forms of iron (FOP+FF) showed significantly lower incidence of clinical staining than the other two groups at the end of 72 h. At the end of 72 h the (FOP) had significantly higher ∆E than ferrous fumarate (FF ) while the combination (FOP+ FF) had a significantly lower ∆E than either group. CONCLUSION: In an in vitro model, combining different forms of iron seems to elicit a lower intensity of staining than equivalent doses of a single form of iron.

Fluoride gel supplemented with sodium hexametaphosphate reduces enamel erosive wear in situ.

OBJECTIVE: This study evaluated the effect of fluoride gels, supplemented or not with sodium hexametaphosphate (HMP), on enamel erosive wear in situ. METHODS: Twelve healthy volunteers wore palatal appliances containing four bovine enamel discs. Subjects were randomly allocated into four experimental phases (double-blind, crossover protocol) according to the gels: Placebo (no fluoride or HMP), 1% NaF, 2% NaF, and 1% NaF+9% HMP. Enamel discs were selected after polishing and surface hardness analysis, and treated only once with the respective gels prior to each experimental phase. Erosion (ERO) was performed by extra-oral immersion of the appliance in 0.05M citric acid, pH 3.2 (four times/day, five minutes each, 5 days). Additional abrasion (ERO+ABR) was produced on only two discs by toothbrushing with fluoridated dentifrice after ERO (four times/day, 30s, 5 days). The specimens were submitted to profilometry and hardness analysis. The results were analyzed by two-way ANOVA and the Student-Newman-Keuls test (p<0.05). RESULTS: The 1% NaF+9% HMP gel promoted significantly lower enamel wear for ERO compared to the other groups, being statistically lower than 1% NaF and Placebo for ERO+ABR. Similarly, the lowest values of integrated lesion area were found for 1% NaF+9% HMP and 2% NaF, respectively, for ERO and ERO+ABR. CONCLUSION: The addition of HMP to the 1% NaF gel promoted greater protective effect against ERO and ERO+ABR compared to the 1% NaF gel, achieving similar protective levels to those seen for the 2% NaF gel. CLINICAL SIGNIFICANCE: Gel containing 1% NaF+9% HMP showed a high anti-erosive potential, being a safer alternative when compared to a conventional 2% NaF gel.

A Randomized Clinical Study Investigating the Stain-Removal Potential of Two Experimental Dentifrices.

OBJECTIVE: To evaluate the ability of two experimental desensitizing dentifrices, both containing a chemical cleaning agent, one with ultra-low abrasivity and one with low abrasivity, a standard fluoride dentifrice, and a daily-use whitening dentifrice to remove extrinsic tooth stain. METHODS: This was a single-center, examiner-blind, randomized, controlled, four-treatment, parallel-group study in healthy adults. Extrinsic stain was evaluated using the Macpherson modification of the Lobene Stain Index (MLSI). At baseline, eligible subjects with a total MLSI (area x intensity [A x I]) score of 15 for the facial surfaces of the 12 anterior teeth were stratified (based on total MLSI [A x I] score [< 45 = low; ≥ 45 = high] and smoking status) and randomized to treatment with one of four dentifrices: an experimental ultra-low abrasivity desensitizing dentifrice (relative dentin abrasion [RDA] -12); an experimental low abrasivity desensitizing dentifrice (RDA -40); a standard fluoride dentifrice with moderate abrasivity (RDA -80); and a whitening dentifrice with higher abrasivity (RDA -142). Both desensitizing dentifrices contained 5% potassium nitrate and 5% sodium tripolyphosphate (a chemical cleaning agent). Treatment effects were evaluated after four and eight weeks of twice-daily brushing. RESULTS: In total, 142 subjects were randomized and 133 subjects completed the study. All study dentifrices demonstrated statistically significant reductions in extrinsic tooth stain from baseline after four and eight weeks of twice-daily use (p < 0.01). There were no statistically significant between-treatment differences for the primary variable (mean MLSI [A x I] score across all assessed sites) at four or eight weeks, and no notable trends were observed. CONCLUSION: All study dentifrices reduced extrinsic tooth stain. The experimental ultra-low and low abrasivity desensitizing dentifrices containing 5% sodium tripolyphosphate performed similarly to both a moderate abrasivity standard fluoride dentifrice and a higher abrasivity whitening dentifrice.

An ex vivo study of arrested primary teeth caries with silver diamine fluoride therapy.

OBJECTIVES: This ex vivo study compared the physico-chemical structural differences between primary carious teeth biannually treated with silver diamine fluoride (SDF) and carious teeth without such treatment. METHOD: Twelve carious primary upper-central incisors were collected from 6-year-old children. Six teeth had arrested caries after 24-month biannual SDF applications and 6 had active caries when there was no topical fluoride treatment. The mineral density, elemental contents, surface morphology, and crystal characteristics were assessed by micro-computed tomography (micro-CT), energy-dispersive X-ray spectrometry (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). RESULTS: Micro-CT examination revealed a superficial opaque band approximately 150µm on the arrested cavitated dentinal lesion. This band was limited in the active carious lesion. EDX examination detected a higher intensity of calcium and phosphate of 150µm in the surface zone than in the inner zone, but this zone was restricted in the active cavitated dentinal lesion. SEM examination indicated that the collagens were protected from being exposed in the arrested cavitated dentinal lesion, but were exposed in the active cavitated dentinal lesion. TEM examination suggested that remineralised hydroxyapatites were well aligned in the arrested cavitated dentinal lesion, while those in the active cavitated dentinal lesion indicated a random apatite arrangement. CONCLUSIONS: A highly remineralised zone rich in calcium and phosphate was found on the arrested cavitated dentinal lesion of primary teeth with an SDF application. The collagens were protected from being exposed in the arrested cavitated dentinal lesion. CLINICAL SIGNIFICANCE: Clinical SDF application positively influences dentine remineralisation.

Effect of agitation of EDTA with 808-nanometer diode laser on removal of smear layer.

INTRODUCTION: Near-infrared diode lasers can be used for several applications, which range from disinfection to smear layer removal in endodontics. This study evaluated the efficacy of agitation of 15% EDTA with an 808-nm diode laser on removal of the smear layer. METHODS: Sixty extracted human maxillary central incisor teeth were instrumented up to ProTaper F4 (Dentsply Maillefer, Ballagues, Switzerland) and then randomly divided into 6 groups (n = 10 for each group) according to the different final irrigating protocols as follows: 5% sodium hypochlorite for 120 seconds performed with the NaviTip (Dentsply Maillefer, Ballaigues, Switzerland) (control group); 15% EDTA for 120 seconds performed with the NaviTip; and agitation of 15% EDTA with an 808-nm diode laser for 10, 20, 30, and 40 seconds. Specimens were observed under a scanning electron microscope, and open dentinal tubules were counted using Adobe Photoshop software (Adobe Systems, San Jose, CA). The data were analyzed with 1-way analysis of variance and Tukey post hoc tests (P = .05). RESULTS: The number of open dentinal tubules was higher in the middle thirds than in the apical thirds. The differences between the apical and middle thirds were statistically significant (P < .05). Statistically significant differences were also found between the control group and the other groups in both the middle and apical thirds of the root canals (P < .05). CONCLUSIONS: The results indicated that agitation of 15% EDTA with an 808-nm diode laser for 20 seconds was effective in removing the smear layer in the apical thirds of root canals.

The whitening effect of chlorine dioxide--an in vitro study.

OBJECTIVES: The aim of this study was to investigate the whitening properties and rate of bleaching action of chlorine dioxide and compare them with those of hydrogen peroxide of similar concentration. METHODS: Sixty bovine central incisor crowns were ground and polished until flat surfaces were obtained. The crowns were subjected to extensive staining cycles of artificial saliva, chlorehexidine and tea before being randomly assigned to three groups: chlorine dioxide (ClO2), hydrogen peroxide (H2O2) and deionised water (H2O). The crowns in each group were subjected to seven 2 min exposure cycles in addition to an extra 30 min cycle. CIE LAB spectrophotometric measurements were taken at baseline, after each 2 min, and each extended 30 min bleaching cycle. RESULTS: L* for ClO2 specimens was significantly higher only after the first 2 min cycle (p<0.001) while for H2O2 specimens, L* significantly increased after the first two cycles (p<0.001) and continued to increase, at a slower rate, until the end of the treatment cycles. ΔE was significantly greater within H2O2 than within ClO2 specimens (p<0.001). CONCLUSION: Chlorine dioxide whitens teeth at a faster rate than hydrogen peroxide. Specimens treated with chlorine dioxide were significantly lighter than those treated with hydrogen peroxide at the end of the first 2 min application cycle, however, extended exposures did not enhance color.

Clinical evaluation of desensitizing treatment for incisor teeth affected by molar-incisor hypomineralization.

BACKGROUND: Sensitivity complaints are commonly observed in teeth affected by MIH (molar incisor hypomineralization). AIM: This study aimed to evaluate the hypersensitivity observed in MIH-affected teeth and the effect of desensitizing agents applied with and without ozone to incisors affected by MIH. STUDY DESIGN: The first part of the study included 120 teeth from 42 patients with MIH. These 42 patients included 33 children with 92 incisor teeth with a Vas score of > or = 30, and these 92 incisors were included in the second part of the study. The patients included in the second part were divided into three main groups and six subgroups. The main groups included the following: fluoride, CPP-ACP and CPP-ACP with fluoride. Each main group was divided into two subgroups: one with ozone use and one without ozone use. RESULTS: Girls exhibited significantly more sensitivity compared with boys (p < 0.05). There were significant decreases in hypersensitivity compared to baseline in all of the groups (p < 0.05). There were no differences among the groups at the end of the study (p > 0.05). CONCLUSION: The results of this study revealed that gender is an important factor in the sensitivity of teeth with MLH. Desensitizing agents effectively reduced the hypersensitivity of teeth with MIH. CPP-ACP paste was found to be more effective, and ozone therapy prolonged the effect of CPP-ACP paste.

Effect of topical anesthesia on pain during infiltration injection and success of anesthesia for maxillary central incisors.

INTRODUCTION: This study was performed to investigate the effect of topical anesthesia on pain during needle penetration and infiltration injection as well as the effect of pain during injection on success rate of anesthesia in maxillary central incisors. METHODS: In a crossover double-blind study, 25 volunteers randomly received either topical anesthesia or placebo before infiltration injection with prilocaine for their maxillary central incisors in 2 separate appointments. The pain after needle penetration and during injection was separately recorded. An electric pulp tester was used to evaluate the success of the anesthetic injection. Data were analyzed by McNemar, Wilcoxon, and χ(2) tests. RESULTS: Overall for 50 injections, 72% of the teeth had successful anesthesia. No significant difference was found between placebo and topical anesthetic groups for the pain of needle penetration as well as pain during injection (P > .05). The volunteers who reported moderate-to-severe pain during injection showed no significant difference in the success rate of anesthesia compared with those with no or mild pain during injections (P > .05). CONCLUSIONS: Use of topical anesthesia had no significant effect on pain during either needle penetration or injection. Pain during injection had no significant effect on the success of anesthesia.

Carisolv as an endodontic irrigant in deciduous teeth: an SEM study.

AIM: Root canal irrigation plays an important role in the debridement and disinfection of the root canal system. "The purpose of this study was to evaluate the efficacy of Carisolv , 1% sodium hypochlorite (NaOCl) gel, and 1% NaOCl solution as root canal irrigants in deciduous anterior teeth." MATERIALS AND METHODS: THIRTY-six extracted deciduous anterior teeth were used. Root canals were flooded with NaOCl solution in Group A, NaOCl gel in Group B and Carisolv in Group C and incubated for 30 min. Scanning electron microscope photomicrographs of canal wall debris in the apical, middle and coronal thirds were scored. RESULTS: The results showed that regardless of irrigation regime, canals were consistently cleaner in the coronal and middle thirds than in the apical thirds. NaOCl solution, NaOCl gel, and Carisolv had comparable activity at coronal third and middle third of root canals. At the apical third, NaOCl solution cleaned canals better than NaOCl gel and Carisolv. Carisolv cleaned debris better than NaOCl gel at the apical third. CONCLUSION: Carisolv can be used as an adjunct to root canal preparation.

Clinical evaluation of the effectiveness of different bleaching therapies in vital teeth.

The aims of this in vivo study were to compare the effectiveness and color stability of at-home and in-office bleaching techniques and to evaluate whether the use of light sources can alter bleaching results. According to preestablished criteria, 40 patients were selected and randomly divided into four groups according to bleaching treatment: (1) at-home bleaching with 10% carbamide peroxide, (2) in-office bleaching with 35% hydrogen peroxide (HP) without a light source, (3) in-office bleaching with 35% HP with quartz-tungsten-halogen light, and (4) in-office bleaching with 35% HP with a light-emitting diode/laser. Tooth shade was evaluated using the VITA Classical Shade Guide before bleaching as well as after the first and third weeks of bleaching. Tooth shade was evaluated again using the same guide 1 and 6 months after the completion of treatment. The shade guide was arranged to yield scores that were used for statistical comparison. Statistical analysis using the Kruskal-Wallis test showed no significant differences among the groups for any time point (P > .01). There was no color rebound in any of the groups. The bleaching techniques tested were equally effective. Light sources are unnecessary to bleach teeth.

Tooth colour change with Ozicure Oxygen Activator: a comparative in vitro tooth bleaching study.

INTRODUCTION: This in vitro study compared a new tooth bleaching product, Ozicure Oxygen Activator (O3, RSA) with Opalescence Quick (Ultradent, USA) using a randomised block design to assess tooth colour change. AIM: Colour change, stability and relapse in canine, incisor and premolar teeth was assessed following three bleach treatments and subsequent tooth colour assessment. METHODS: Ninety nine teeth (canines, incisors and premolars), which were caries free, had no surface defects and were within the colour range 1M2 and 5M3 were selected. Teeth were randomly divided into the three experimental groups: Opalescence Quick, Ozicure Oxygen Activator and control. The three experimental groups received three treatments of one hour each over three consecutive days. Tooth colour was assessed using the Vitapan 3D Master Tooth Guide (VITA, Germany). A General Linear Models test for analysis of variance for a fractional design with significance set at P < 0.05 was used to test for significance. RESULTS: Both bleaching methods significantly lightened the teeth (P < 0.0001). Tooth colour change was mainly after the first hour of tooth bleaching. The tooth type was significant in tooth colour change (P = 0.0416). Tooth colour relapse and resistance to colour change were observed. CONCLUSIONS: Ozicure Oxygen Activator bleached teeth in a manner and to an extent similar to Opalescence Quick.

Effects of chelating agents on the mineral content of root canal dentin.

OBJECTIVE: The objective of this in vitro study was to assess the effect of several chelating agents on the mineral content of root dentin. STUDY DESIGN: Extracted human mandibular incisor roots were prepared and divided into groups according to the following irrigation protocols: 1) 17% ethylenediaminetetraacetic acid (EDTA); 2) 10% citric acid solution; 3) 18% etidronate; 4) 2.25% peracetic acid; 5) and deionized water (control). Dentin chips were obtained (Gates-Glidden nos. 3, 4, and 5). The levels of different minerals were analyzed with the use of inductively coupled plasma-atomic emission spectrometry (ICP-AES). RESULTS: 1) Peracetic acid significantly decreased P, K, Mg, Na, and S levels compared with the other groups (P < .05). 2) S decreased by different levels in all of the chelating solutions (P < .05), and the greatest decrease was observed in peracetic acid. 3) Ca levels significantly decreased in peracetic acid, citric acid, and EDTA (P < .05). 4) Mn levels significantly decreased in the citric acid and peracetic acid groups (P < .05). 5) Na and Zn levels significantly decreased in the peracetic acid, citric acid, and etidronate groups (P < .05). CONCLUSIONS: The chelation agents can create different effects on mineral contents of root dentin, so it is important to know what effects each solution will have on root dentin before their clinical use. In addition, according to the results of this in vitro study, it might be recommended that peracetic acid, in particular, should be used with caution.