Histopathology of the pulp of primary molars with active and arrested dentinal caries

The purpose of this study was to compare the histological appearance of the pulp of human primary molars with active and arrested lesions. The sample consisted of 36 primary molars (18 with active lesions and 18 with arrested lesions) extracted from 35 children between 5 to 9 years of age. The histological diagnosis was classified in normal pulp, transitional stage, partial pulpitis, total pulpitis and total necrosis, and then subdivided in three subgroups: treatable, untreatable and questionable. Results showed that normal pulp or transitional stage (treatable category) was diagnosed in 50% of teeth with arrested lesions, compared to 11.1% of teeth with active lesions. Partial pulpitis (questionable category) was present in 38.8% with arrested lesions compared to 22.2% with active lesions. Total pulpitis and total necrosis (untreatable category) was diagnosed in 11.2% with arrested lesions compared to 66.7% with active lesions. The observed frequencies of histological categories between both groups were statistically significant (P < 0.05). Histologically, pulp reaction under active and arrested lesions in primary molars revealed the formation of a basophilic calcio-traumatic line at the junction of the primary and reparative dentin, formation of reparative dentin and a regular odontoblastic layer in 60% of the cases. Results indicated that the type of lesion (active or arrested) is a good indicator of the histological status of the pulp.

Effect of time interval between bleaching and bonding on tag formation

The objective of this study was to assess penetration of adhesive material in enamel bleached with 35% hydrogen peroxide using optical polarized light microscopy. Extracted human teeth were randomly assigned to 5 groups, each representing a specific time interval between bleaching and the application of an adhesive material. They were designated as: (TC) the control group-restorations in unbleached teeth; (T0) comprising restorations carried out immediately after bleaching; (T7) comprising restorations 7 days after bleaching; (T14) comprising restorations 14 days after bleaching; and (T21) comprising restorations 21 days after bleaching. Length of resin tags was measured with an Axiophot photomicroscope at a x 400 magnification, and the results subjected to an ANOVA for a comparison between groups, with a p value of < 0.05. Differences between the groups were verified using a Tukey test at a confidence level of 5%. The specimens in the control group (TC) and experimental groups T7, T14 and T21 showed better penetration of adhesive material into enamel in comparison with experimental group T0. This suggests that a gap of at least 7 days should be left between bleaching enamel with 35% hydrogen peroxide and placing adhesive bonding agents and undertaking resin composite restoration work.

Influence of the quantity of coloring agent in bleaching gels activated with LED/laser appliances on bleaching efficiency

The aim of this study was to assess the influence of the quantity of coloring agent on the bleaching efficiency of gels containing 35% H2O2. Sixty human third molars were sectioned mesiodistally, darkened in a coffee solution and sectioned in the occlusal-cervical direction, resulting in mesial (not bleached) and distal halves (bleached). They were distributed into three groups: Whiteness HP, Total Bleach, and Whiteform Perox Red Gel; and subdivided into four sub-groups: no coloring agent, manufacturer's standard, double the standard, and triple the standard. The gels were activated with light-ermitting diode/laser appliances. The images were analyzed with the Adobe Photoshop program (deltaEL*a*b*). The variation was submitted to the ANOVA test (two factors: type of gel and quantity of coloring agent) and Tukey test. Differences were observed for the quantity of coloring agent. The mean (+/-SD) was determined for each quantity of coloring used: no coloring agent -6.85 (+/-2.26)a, manufacturer's standard -794 (+/-2.55)ab, double the standard -8.65 (+/-2.47)b, triple the standard -9.05 (+/-2.72)b. In conclusion, the standard quantity of coloring agent did not provide significantly more intense bleaching than when it was completely absent. The use of double and triple the amount provided greater bleaching than that observed for the gel without coloring agent. No significant differences were observed between the tested gels.

Effects of dental bleaching on the color, translucency and fluorescence properties of enamel and dentin

The objective of this study was to evaluate the color, translucency and fluorescence of bovine enamel and dentin submitted to different bleaching modalities. Pairs of enamel and dentin discs (3 mm in diameter) were obtained from 150 bovine teeth. In 75 of the pairs, one specimen had the enamel removed (Dentin Group). The dentin was removed from one specimen of the remaining 75 pairs (Enamel Group) and the other specimen was left unaltered (Enamel + Dentin). The evaluation of color, translucency and fluorescence was performed with a spectrophotometer using the CIE L* a* b*. Each group was subdivided into three subgroups: Control, composed of specimens that were not bleached, and two experimental subgroups, bleached with either 10% carbamide peroxide (CP10%) or 35% hydrogen peroxide (HP35%). The CP10% bleaching gel was applied 2 h/day for 14 days. The HP35% bleaching agent was applied using two applications of 30 min each, with a one week interval between each application. When not being bleached, the specimens were immersed in artificial saliva. The color, translucency and fluorescence ratings were assessed using spectrophotometry 7 days after the treatment. Regarding color, significant differences were found between bleaching techniques in the groups Enamel and Enamel + Dentin, with a higher color difference for HP35%. Bleaching did not change the translucency of the dental tissues. There were significant differences for fluorescence for the HP35% subgroups of Dentin and Enamel + Dentin, and for the CP10% subgroup of Enamel. Dental bleaching changed the color and fluorescence of the dental tissues, however translucency was not affected.

Effect of chemical activation of 10% carbamide peroxide gel in tooth bleaching

This study aimed to evaluate the efficacy of chemical agents to increase the bleaching effectiveness of 10% carbamide peroxide. Two hundred and ninety enamel-dentin discs were prepared from bovine incisors. The color measurement was performed by a spectrophotometer using the CIE L*a*b*system. The groups were divided according to the bleaching treatment: negative control group (NC): without bleaching; positive control group (PC): bleached with 10% carbamide peroxide gel without any chemical activator; Manganese gluconate (MG); Manganese chloride (MC); Ferrous gluconate (FG); Ferric chloride (FC); and Ferrous sulphate (FS). Three different concentrations (MG, MC, FG, FC: 0.01, 0.02 and 0.03% w/w; FS: 0.001, 0.002 and 0.003% w/w) for each agent were tested. The bleaching gel was applied on the specimens for 8 h, after which they were immersed in artificial saliva for 16 h, during 14 days. Color assessments were made after 7 and 14 days. The data were analyzed by repeated measures analysis of variance and Tukey's test (5%). Generally, the test groups were unable to increase the bleaching effect (ΔE) significantly compared to the PC group. Only for ΔL, significant higher values compared to the PC group could be seen after 7 days in groups MG (0.02%), and FS (0.002 and 0.003%). The NC group showed significantly lower values than all tested groups. It was concluded that for home bleaching procedures, the addition of chemical activators did not produce a bleaching result significantly higher than the use of 10% carbamide peroxide without activation, and that the concentration of chemical activators used did not significantly influence the effectiveness of treatment.

Effect of incorporation of remineralizing agents into bleaching gels on the microhardness of bovine enamel in situ

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of simulated pulpal pressure on efficacy of bleaching gels

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Diabetes triggers the loss of tooth structure associated to radiographical and histological dental changes and its evolution to progressive pulp and periapical lesions in rats

The aim of this study was to evaluate the putative influence of diabetes without metabolic control in the loss of tooth structure as well as histological changes in dentin and pulp tissue in rats. Diabetes was induced in Wistar rats (n=25) by intravenous administration of alloxan (42mg/kg). Diabetic and non-diabetic control rats were evaluated at 1, 3, 6, 9 and 12 months of follow-up. In order to evaluate the presence and progression of dental caries and periapical lesions, hemimandibles were removed and submitted to radiographical, histological, and morphometrical procedures. Dental caries were detected after radiographical and histological evaluations in diabetic group from the third month of diabetes onset, increasing gradually in frequency and severity in periods. Diabetic rats dental pulps also presented significant reduction in volume density of collagen fibers and fibroblasts at third month, parallel with a trend towards the increase in inflammatory cells volume density. Diabetic rats presented a generalized pulp tissue necrosis after 6 months of diabetes induction. Moreover, periapical lesions were not detected in control group, while these lesions were observed in all rats after 3, 6, 9, and 12 months of diabetes induction. Uncontrolled diabetes seems to trigger the loss of tooth structure, associated to histological dental changes and mediates its evolution to progressive severe pulp and periapical lesions in rats. Therefore, diabetes may be considered a very important risk factor regarding alterations in dental pulp, development of dental caries, and periapical lesions.

Demineralization and hydrogen peroxide penetration in teeth with incipient lesions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effectiveness of 6% hydrogen peroxide concentration for tooth bleaching-A double-blind, randomized clinical trial

The aim of this clinical randomized double-blind split-mouth study was to assess the effectiveness of a 6% hydrogen peroxide with nitrogen-doped titanium dioxide light activated bleaching agent. 31 patients were treated with: one upper hemiarcade with a 35% hydrogen peroxide bleaching agent and the other hemiarcade with a 6% hydrogen peroxide. Two applications were completed each treatment session and three sessions were appointed, with one week interval between them. Tooth colour was registered each session and 1 week and 1 months after completing the treatment by spectrophotometer, registering parameters L*, a* and b*, and subjectively using VITA Classic guide. Tooth sensitivity was registered by VAS and patient satisfaction and self-perception result was determined using OHIP-14. Tooth colour variation and sensitivity were compared between both bleaching agents. Both treatment showed a change between baseline colour and all check-points with a ΔE=5.57 for 6% and of ΔE=7.98 for the 35% one month after completing the (p<0.05). No statistical differences were seen when subjective evaluations were compared. Also, no differences were seen in tooth sensitivity between bleaching agents. OHIP-14 questionnaire demonstrated a significant change for all patients after bleaching. A 6% hydrogen peroxide with nitrogen-doped titanium dioxide light activated agent is effective for tooth bleaching, reaching a ΔE of 5.57 one month after completing the treatment, with no clinical differences to a 35% agent neither in colour change or in tooth sensitivity. A low concentration hydrogen peroxide bleaching agent may reach good clinical results with less adverse effects.

Effect of home-bleaching gels modified by calcium and/or fluoride and the application of nano-hydroxyapatite paste on in vitro enamel erosion susceptibility

This in vitro study compared the effect of bleaching agents modified by the addition of calcium and/or fluoride and the application of a nano-hydroxyapatite paste after bleaching, on the susceptibility of enamel to erosion. Bovine enamel cylindrical samples (3 mm diameter) were assigned to six groups (n = 20 specimens/group) according to the bleaching agent: no bleaching (C-control), 7.5% hydrogen peroxide gel (HP), HP with 0.5% calcium gluconate (HP+Ca), HP with 0.2% sodium fluoride (HP+F), HP with calcium and fluoride (HP+Ca+F) and HP followed by the application of a nano-hydroxyapatite agent (HP+NanoP). The gels were applied on the enamel surface (1 h) followed by cyclic erosive challenges (Sprite Zero®-2 min), for 14 days. The paste was applied after bleaching for 5 min (HP+NanoP). The enamel surface alteration was measured by contact profilometry (µm) (after 7 and 14 days). C-control (mean ± SD: 2.29 ± 0.37 at 7 days/4.86 ± 0.72 at 14 days) showed significantly lower loss compared to the experimental groups. HP+Ca (3.34 ± 0.37/6.75 ± 1.09) and HP+F (4.49 ± 0.92/7.61 ± 0.90) presented significantly lower enamel loss than HP (4.18 ± 0.50/10.30 ± 1.58) only for 14 days and HP+Ca+F (4.92 ± 1.03/8.12 ± 1.52) showed values similar to the HP+F group. The HP+NanoP (5.51 ± 1.04/9.61 ± 1.21) resulted in enamel loss similar to the HP after 14 days. It was found that 7.5% hydrogen peroxide increased the susceptibility of enamel to erosion. The addition of calcium or fluoride to the bleaching gel reduced the erosion effect, while the nano-hydroxyapatite agent did not provide any protective effect.

Transdentinal cytotoxicity of resin-based luting cements to pulp cells

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudos da polpação kraft, branqueamento e refino de eucalyptus grandis x eucalyptus urophylla

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Dental bleaching with a 10% hydrogen peroxide product: a six-month clinical observation

Context: The possibility of bleaching vital teeth with peroxide-based products considerably revolutionized esthetic dentistry. Aim: The aim of this clinical study was to evaluate tooth color change and dental sensitivity after exposure to preloaded film containing a 10% hydrogen peroxide whitening system (Opalescence Trθswhite Supreme). Materials and Methods: A total of 13 volunteers, aged 18 to 25 years, participated in this study. The patients used the whitening system once a day for 60 minutes during the 8-day study. For maxillary incisors and canines, the color change was visually evaluated with the Vita color scale before, immediately, and six months after the treatment. Tooth sensitivity was evaluated during the daily gel applications. All whitening applications were done in office and under the supervision of a dental professional. Statistical Analysis Used: The results were analyzed using the Friedman Test (nonparametric repeated measures ANOVA) at a level of 5%, and Dunn's Multiple Comparison Test at the level of 5%. Results: It was verified that the original mean color values observed at the baseline analysis differed significantly from those observed immediately after bleaching, as well as from those seen in the analysis at six months ( P = 0.001). There was no significant difference between the mean color values observed in the immediate time and in the analysis at six months ( P = 0.474). No tooth sensitivity was observed in any patients. Conclusion: It was concluded that the bleaching technique using the 10% hydrogen peroxide system was effective in a short period of time without tooth sensitivity during applications.

Smile restoration through use of enamel microabrasion associated with tooth bleaching

Enamel microabrasion can eliminate enamel irregularities and discoloration defects, improving the appearance of teeth. This article presents the latest treatment protocol of enamel microabrasion to remove stains on the enamel surface. It has been verified that teeth submitted to microabrasion acquire a yellowish color because of the thinness of the remaining enamel, revealing the color of dentinal tissue to a greater degree. In these clinical conditions, correction of the color pattern of these teeth can be obtained with a considerable margin of clinical success using products containing carbamide peroxide in custom trays. Thus, patients can benefit from combined enamel microabrasion/tooth bleaching therapy, which yields attractive cosmetic results. Esthetics plays an important role in contemporary dentistry, especially because the media emphasizes beauty and health. Currently, in many countries, a smile is considered beautiful if it imitates a natural appearance, with clear, well-aligned teeth and defined anatomical shapes.1-3 Enamel microabrasion is one technique that can be used to correct discolored enamel. This technique has been elucidated and strongly advocated by Croll and Cavanaugh since 1986,4 and by other investigators1,2,5-13 who suggested mechanical removal of enamel stains using acidic substances in conjunction with abrasive agents. Enamel microabrasion is indicated to remove intrinsic stains of any color and of hard texture, and is contraindicated for extrinsic stains, dentinal stains, for patients with deficient labial seals, and in cases where there is no possibility to place a rubber dam adequately during the microabrasion procedure.1,2 It should be emphasized that enamel microabrasion causes a microreduction on the enamel surface,3,6,10 and, in some cases, teeth submitted to microabrasion may appear a darker or yellowish color because the thin remaining enamel surface can reveal some of the dentinal tissue color. In these situations, according to Haywood and Heymann in 1989,14 correction of the color pattern of teeth can be obtained through the use of whitening products containing carbamide peroxide in custom trays. A considerable margin of clinical success has been shown when diligence to at-home protocols is achieved by the patient and supervised by the professional.3 Considering these possibilities, this article presents the microabrasion technique for removal of stains on dental enamel, followed by tooth bleaching with carbamide peroxide and composite resin restoration, if required. - See more at: https://www.dentalaegis.com/cced/2011/04/smile-restoration-through-use-of-enamel-microbrasion-associated-with-tooth-bleaching#sthash.N6jz2Bwk.dpuf