Effect of CO2 laser on root caries inhibition around composite restorations: an in vitro study.

The aim of the present study was to investigate the in vitro effect of CO2 laser on the inhibition of root surface demineralization around composite resin restorations. For this purpose, 30 blocks obtained from human molar roots were divided into three groups: group 1 (negative control), cavity prepared with cylindrical diamond bur + acid etching + adhesive + composite resin restoration; group 2, cavity prepared with cylindrical diamond bur + CO2 laser (5.0 J/cm(2)) + acid etching + adhesive + composite resin; and group 3, cavity prepared with cylindrical diamond bur + CO2 laser (6.0 J/cm(2)) + acid etching + adhesive + composite resin. After this procedure, the blocks were submitted to thermal and pH cycling. Root surface demineralization around the restorations was measured by microhardness analysis. The hardness results of the longitudinally sectioned root surface were converted into percentage of mineral volume, which was used to calculate the mineral loss delta Z (ΔZ). The percentage of mineral volume, ΔZ, and the percentage of demineralization inhibition of the groups were statistically analyzed by using analysis of variance and Tukey-Kramer test. The percentage of mineral volume was higher in the irradiated groups up to 80 µm deep. The ΔZ was significantly lower in the irradiated groups than in the control group. The percentage of reduction in demineralization ranged from 19.73 to 29.21 in position 1 (50 µm), and from 24.76 to 26.73 in position 2 (100 µm), when using 6 and 5 J/cm(2), respectively. The CO2 laser was effective in inhibiting root demineralization around composite resin restorations.

Influence of Different Surface Treatments on the Bond Strength of Yttria-Stabilized Tetragonal Zirconia Ceramic.

Objective: This in vitro study evaluates the shear bond strength (SBS) of yttria-stabilized tetragonal zirconia (Y-TZP) and resin cement after different surface treatments. Materials and methods: Forty-eight ceramic cubes were divided into four groups (n = 12): G1 (control) sandblasting with Al2O3; G2-sandblasting with silica-coated Al2O3 (Rocatec); G3-Rocatec + CO2 laser; and G4-CO2 laser + Rocatec. A metallic primer was applied to the pretreated ceramic. A rubber ring was adapted on the central area, and then, the resin cement was inserted into the matrix and photoactivated. The samples were evaluated regarding surface roughness (Ra), SBS, failure type, and qualitatively with scanning electron microscopy (SEM). The data were analyzed by one-way analysis of variance followed by Tukey's test (p < 0.05). Results: The mean values of Ra (µm) were as follows: G1-4.52a, G2-4.24a,b, G3-4.10a,b, and G4-2.90b and the mean values of SBS (MPa) were as follows: G1-7.84a , G2-4.41b , G3-4.61b and G4-6.14a,b. SEM analyses showed superficial irregularities for all groups, being more prominent for G1. The presence of silica deposits was observed for G2, G3, and G4, but in the last two groups there were some linear areas, promoted by the fusion of silica, due to the thermomechanical action of the CO2 laser. Conclusions: The surface treatment with CO2 laser + Rocatec, using one MDP-based cement, can be an alternative protocol for the adhesion cementation of Y-TZP ceramic since it was as effective as the conventional pretreatment with aluminum oxide sandblasting.

Microtensile bond strength of composite resin to human enamel prepared using erbium: Yttrium aluminum garnet laser.

The Erbium: Yttrium Aluminum Garnet (YAG) laser used for preparation of cavity can alter the substrate and it could influence the bond strength of enamel. The aim of this in vitro study was to evaluate the influence of Er:YAG laser's energy using microtensile bond test. Three groups were obtained (cavity preparation) and each group was divided into two subgroups (adhesive system). After that the adhesive protocol was performed, sections with a cross-sectional area of 0.8 mm2 (+/-0.2 mm2) were obtained. The specimens were mounted in a universal testing machine (0.5 mm/min). Statistical analysis showed a decrease in bond strength for lased groups (p < 0.01) and when the total-etching adhesive system was used the laser 300 mJ subgroup showed higher bond strength compared to the laser 250 mJ (p < 0.01). It was concluded that the cavities prepared using laser appear less receptive to adhesive procedures than conventional bur-cut cavities.

Effect of feldspathic ceramic surface treatments on bond strength to resin cement.

OBJECTIVE: The objective of this study was to evaluate the shear bond strength of resin cement to feldspathic ceramic with various surface treatments. BACKGROUND DATA: Application of adhesive techniques is well established in restorative dentistry, yet the influence of surface treatments on the bond strength of resin cement to ceramic materials prior to luting or repair procedures remains unclear. METHODS: One hundred samples made of a feldspathic ceramic were divided into 10 groups (n = 10): (1) control (no treatment); (2) 10% hydrofluoric acid (HF); (3) 37% phosphoric acid (H(3)PO(4)); (4) 1.23% acidulated phosphate fluoride acid (APF); (5) diamond bur; (6) air abrasion with Al(2)O(3); (7) Al(2)O(3) + HF; (8) CoJet-Sand; (9) Er:YAG laser, and (10) Al(2)O(3) + Er:YAG laser. Afterwards, silane was applied and a resin cement cylinder was built. After 24 hours at 37 degrees C, the prepared specimens were submitted to a shear bond strength test and stereoscopic evaluation to determine the type of failure after rupture. RESULTS: Bond strength means were statistically different for the different surface treatments. The highest bond strengths were obtained with HF, CoJet-Sand, and Al(2)O(3). The groups treated with Al(2)O(3) + Er:YAG laser, diamond bur, and Al(2)O(3) + HF had moderate bond strengths. The lowest bond strengths were obtained with H(3)PO(4), APF, Er:YAG laser, and the control group. CONCLUSIONS: The HF, CoJet-Sand, and Al(2)O(3) techniques were the most effective surface treatments. The null surface treatment proposed with the Er:YAG laser showed low bond strength, and seems to be inadequate for clinical use with the parameters tested.

Shear bond strength of glass-ionomer cements to air-abraded dentin.

PURPOSE: The aim of this in vitro study was to evaluate the shear bond strength of two conventional glass-ionomer cements to bovine dentin when using the air-abrasion technique for cavity preparation. MATERIALS AND METHODS: Forty bovine central incisors were selected, embedded in polyester resin, and ground until the dentin surface was exposed. The teeth were randomly assigned to four groups: I and II--rotating instrument with a carbide bur; III and IV--an air-abrasion system. Groups I and III were restored with Fuji IX and groups II and IV with Ketac Molar. A 3-mm-diameter bonding site was delimited and treated with 10% polyacrylic acid for 10 s in the Fuji IX subgroups and with 25% polyacrylic acid for 10 s in the Ketac Molar subgroups. After surface treatment, a glassionomer cylinder was prepared for each specimen, using a split bisected Teflon matrix. The finished specimens were submitted to the shear bond strength test in a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed using ANOVA and Scheffé statistical tests. The dentin bonding areas were analyzed under a stereoscopic optical magnifier (40X) to assess the type of failure. RESULTS: The mean (SD) shear bond strengths in MPa were: group I--3.49 (+/- 3.77), group II--7.17 (+/- 2.93), group III--7.55 (+/- 2.99), group IV--5.67 (+/- 3.90). Ketac Molar showed higher bond strength values in bur-prepared cavities, while on the air-abraded preparations, Fuji IX showed superior results. CONCLUSION: It can be concluded that the air-abrasion system used for cavity preparations may influence the bonding performance of conventional glass-ionomer cements to dentin.

Talon Cusp Type I: Restorative Management.

The teeth are formed during intrauterine life (i.e., gestation) during the odontogenesis stage. During this period, the teeth move until they enter the oral cavity. This course covers various stages of dental development, namely, initiation, proliferation, histodifferentiation, morphodifferentiation, and apposition. The talon cusp is an anomaly that occurs during morphodifferentiation, and this anomaly may have numerous adverse clinical effects on oral health. The objective of this study was to report a case of "Talon Cusp Type I" and to discuss diagnostic methods, treatment options for this anomaly, and the importance of knowledge of this morphological change among dental professionals so that it is not confused with other morphological changes; such knowledge is required to avoid unnecessary surgical procedures, to perform treatments that prevent caries and malocclusions as well as enhancing aesthetics, and to improve the oral health and quality of life of the patient.

Effects of near infrared laser radiation associated with photoabsorbing cream in preventing white spot lesions around orthodontic brackets: an in vitro study.

OBJECTIVE: The present study aims to investigate the effect of a low-power infrared laser on the inhibition of bovine enamel demineralization around orthodontic brackets. BACKGROUND DATA: Near infrared lasers have been suggested as alternative approaches because they may produce an increase in resistance to dental caries. METHODS: Forty-eight blocks of enamel obtained from bovine incisor teeth were divided into six groups: Group 1 (control), without treatment; Group 2 (C), photoabsorbing cream; Group 3 (CF), photoabsorbing cream with fluoride; Group 4 (L), irradiation with low-level infrared laser (λ=830 nm) at an energy density of 4.47 J/cm2; Group 5 (L+C), photoabsorbing cream followed by low-level infrared laser irradiation; and Group 6 (L+CF), photoabsorbing cream with fluoride followed by low-level infrared laser irradiation. After these procedures, the enamel blocks received an assortment of orthodontic brackets and were then submitted to pH cycling to simulate a highly cariogenic challenge. The enamel surface demineralization around the orthodontic brackets, according to the different treatments, was quantified by fluorescence loss analysis by quantitative light-induced fluorescence (QLF). The fluorescence loss, expressed as ΔF (percentage of loss fluorescence), was statistically examined by analysis of variance and the Tukey test. RESULTS: The control group (-10.48±2.85) was statistically similar to Group C (-14.52±7.80), which presented the lowest values of ΔF when compared with Groups FC (-3.67±3.21), L (-2.79±1.68), CL (-1.05±0:50), and CFL (-0.60±0:43). However, Groups FC, L, CL, and CFL showed no statistically significant differences among them. CONCLUSIONS: It can be concluded that both the low-level infrared laser and photoabsorbing cream with fluoride were effective in inhibiting the development of caries in enamel around orthodontic brackets, even in situations of high cariogenic challenge.

Influence of aluminum oxide sandblasting associated with Nd:YAG or Er:YAG lasers on shear bond strength of a feldspathic ceramic to resin cements.

OBJECTIVE: This in vitro study evaluated the influence of the surface pretreatment of a feldspathic ceramic on the shear bond strength of two different resin cements. BACKGROUND DATA: Although several conventional surface treatments have been used on feldspathic ceramic, few studies have investigated the effects of an alternative surface treatment, the association of aluminum oxide sandblasting with Nd:YAG and Er: YAG lasers. METHODS: Sixty samples made of a feldspathic ceramic were divided into three groups (n = 20) and treated with (1) controlled-air abrasion with Al(2)O(3) + 10% hydrofluoric acid (HF), (2) Al(2)O(3) + Er:YAG laser, and (3) Al(2)O(3) +Nd:YAG laser. Afterward, silane (Dentsply) was applied on each treated surface. Each of the three main groups was divided into two subgroups (n = 10), where a different resin cement was employed for each subgroup. It was built a cylinder with resin cement (RelyX Arc) in subgroup (A) and with self-adhesive cement (RelyX U100) in subgroup (B). After 24 h at 37 degrees C, the prepared specimens were submitted to shear bond strength test and stereoscopic evaluation to determine the type of failure. RESULTS: Bond strength mean values were not statistically significant for the surface treatment methods or resin cements. CONCLUSION: The null surface treatment proposed with aluminum oxide sandblasting associated with the Er:YAG or Nd:YAG laser and using cementation with self-adhesive cement can be an alternative bonding technique for feldspathic ceramic, since it was as effective as the conventional treatment with aluminum oxide sandblasting and hydrofluoric acid using the conventional resin cement.

Clinical comparison between the bleaching efficacy of 37% peroxide carbamide gel mixed with sodium perborate with established intracoronal bleaching agent.

OBJECTIVE: The aim was to evaluate the bleaching efficacy of sodium perborate/37% carbamide peroxide paste and traditional sodium perborate/distilled water for intracoronal bleaching. STUDY DESIGN: Thirty patients with dark anterior teeth were divided into 2 groups (n = 15): group A: sodium perborate/distilled water; and group B: sodium perborate/37% carbamide peroxide paste. The bleaching treatment limited each patient to the maximum of 4 changes of the bleaching agent. Initial and final color shades were measured using the Vita Lumin shade guide. RESULTS: Data was analyzed with Wilcoxon test for initial and final comparison according to the bleaching agent, demonstrating efficacy of the bleaching treatment with both agents. Mann-Whitney test was used for comparison of the efficacy of the bleaching agents, showing that there was no significant difference between them. CONCLUSION: The sodium perborate/37% carbamide peroxide association for intracoronal bleaching has proven to be as effective as sodium perborate/distilled water.

Tensile bond strength of different adhesive systems to enamel and dentin.

The aim of this study was to assess the tensile bond strength of four adhesive systems to enamel and dentin: Clearfil Liner Bond 2V - C, Prime&Bond NT/NRC - PB, Single Bond - SB and All Bond 2 -AB. For such purpose, 40 sound human molars were selected. Crowns were bisected in a mesiodistal direction and each half was ground until flat enamel (E) or dentin (D) surfaces were obtained. A total of 80 specimens were randomly assigned to 4 groups (n=20, 10 in enamel and 10 in dentin). After surface treatment, a composite resin (Z250; 3M) cone was prepared using a split Teflon(R) matrix. Bond strength was tested in an universal testing machine (0.5 mm/min). Bond strength means in MPa were: C - E: 18.66 (+/-2.67) and D: 21.62 (+/-5.29); PB - E: 18.13 (+/-2.96) and D: 3.19 (+/-1.40); SB - E: 20.06 (+/-6.11) and D: 16.95 (+/-2.57); AB - E: 18.20 (+/-3.94) and D: 15.94 (+/-4.72). Statistical analysis of data by two-way ANOVA showed that C presented the best results followed by SB. In conclusion, among the tested materials, Clearfil Liner Bond 2V self-etching primer adhesive syetem had the best performance. The substrate type influenced bond strength, being higher to enamel.

Effect of cavity preparation method on microtensile bond strength of a self-etching primer vs phosphoric acid etchant to enamel.

This study evaluated the effect of cavity preparation using air abrasion or carbide bur on bond strength to enamel treated with a self-etching primer (Tyrian SPE) or a phosphoric acid etchant. Twenty-four molars were divided into three groups: high-speed; standard handpiece (ST air abrasion) or supersonic handpiece (SP air abrasion) of the same air-abrasive system. The enamel surfaces were treated with one of the two etchants and the same adhesive agent One Step Plus, and then composite buildups were done with Filtek Z250. After 24 h at 37 degrees C, beams (0.8 mm2) were obtained and subjected to tensile stress in a universal testing machine (0.5 mm/min). The data were submitted to analysis of variance and Tukey's test (P < 0.05). For the conditioning agents, it was observed that the specimens conditioned with phosphoric acid presented superior results than the specimens that used Tyrian SPE. For the preparation techniques, it was verified that the SP air abrasion groups showed the highest bond strengths and carbide-bur groups presented the lowest bond strengths when the specimens were conditioned with Tyrian SPE. It can be concluded that the influence of the cavity preparation method was dependent on the conditioning system used, only when using carbide-bur preparation technique.

Infiltrante resinoso vs Microabrasão no manejo de lesões de mancha branca: relato de caso / Resin infiltration vs microabrasion in white-spot lesions treatment: case report

Objetivo: Apresentar caso clínico de tratamento estético das lesões de mancha branca após tratamento ortodôntico nos dentes superiores anteriores através de duas técnicas minimamente invasivas usando o sistema de infiltração de resina e microabrasão. Relato de caso: Paciente com 18 anos de idade apresentava lesões de manchas brancas inativas nos dentes 11, 12, 13, 21, 22, 23. O sistema de infiltrante de resina Icon (DMG, Hamburgo, Alemanha) foi utilizado nos dentes 11, 12, 13, enquanto os dentes 21, 22, 23 foram submetidos à microabrasão com Whiteness RM (FGM, Joinville, Santa Catarina, Brasil).Ambos os protocolos foram utilizados de acordo com as recomendações do fabricante.Nos dentes 21 e 22, o produto para microabrasão foi aplicado com espátula que acompanha o kit, enquanto que no dente 23 utilizou-se o mesmo produto aplicado com taça de borracha em baixa rotação, todos os procedimentos executados por um único operador. A microabrasão com taça de borracha proporcionou uma superfície mais lisa e homogênea.Ambos os produtos tiveram resultados satisfatórios na resolução estética das lesões de mancha branca após um ano de acompanhamento. Conclusão: Os dois produtos apresentam bom desempenho e resolutividade para os problemas estéticos de lesões de manchas brancas inativas, entretanto deve-se levar em conta o tempo clínico, toxicidade, a atividade da lesão e a possibilidade de desgaste da estrutura dentária.

Objective: To present a case report of aesthetic treatment of post orthodontic white--spot lesions in the anterior superior teeth through two minimally invasive technique susing resin infiltration system or microabrasion. Case report: Patient 17 years of age had inactive white-spots lesions on teeth 11, 12, 13, 21, 22, 23. The teeth 11, 12, 13 received the resin infiltrating system Icon (DMG, Hamburg, Germany) while the teeth 21, 22, 23were submitted to microabrasion with Whiteness RM (FGM, Joinville, Santa Catarina, Brazil). Both protocols were used according to manufacturer’s recommendations. In the teeth 21 and 22, the product of the microabrasion was applied with a spatula that accompanied the kit, while the tooth 23 received the same product applied with a rubbercup at low speed turbine, all by a single operator. The microabrasion with rubber cupoccasioned a more smooth and homogeneous surface. Both products had satisfactory results in aesthetic resolution of the white-spots lesions, for a 1-year follow-up. Conclusion:Although both products are able to resolve aesthetic problems of inactive white-spots lesions, it should be taken into account the clinical time, toxicity, the activity ofthe lesion and the possibility of wear of the tooth structure.

Microhardness of composite resins at different depths varying the post-irradiation time

OBJECTIVE: The purpose of this study was to assess the microhardness of posterior composite resins at different depths varying the post-irradiation time. MATERIALS AND METHODS: For each composite resin [Solitaire 2 (SO) - Heraus Kulzer, P60 (P) - 3M, Prodigy Condesable (PC) - Kerr, Surefil (S) - Dentsply and Alert (A) - Pentron], 6 specimens (3 mm in diameter; 4mm high) were prepared using a black polyurethane cylindrical matrix. The resins were inserted in a bulk increment and light cured for 40 seconds. Microhardness was analyzed at different depths (top, 0.4 mm, 1.0 mm, 2.0mm, 3.0 mm and 4.0 mm) and at two moments (20 minutes and 24 hours after light-curing). Data were analyzed by ANOVA and Tukey's test (p<0.05). RESULTS: Overall, microhardness means decreased significantly with the increase of depth, being lower in the first moment tested. P, S and PC showed the highest microhardness means. CONCLUSION: It may be concluded that the tested composite resins presented a gradual decrease of microhardness as depth increased and this drop was more accentuated for depths beyond 2 mm. For all materials, higher microhardness means were recorded 24 hours after light activation. P60 yielded the best results at the different depths evaluated.

Tensile bond strength of different adhesive systems to enamel and dentin

The aim of this study was to assess the tensile bond strength of four adhesive systems to enamel and dentin: Clearfil Liner Bond 2V - C, Prime&Bond NT/NRC - PB, Single Bond - SB and All Bond 2 -AB. For such purpose, 40 sound human molars were selected. Crowns were bisected in a mesiodistal direction and each half was ground until flat enamel (E) or dentin (D) surfaces were obtained. A total of 80 specimens were randomly assigned to 4 groups (n=20, 10 in enamel and 10 in dentin). After surface treatment, a composite resin (Z250; 3M) cone was prepared using a split Teflon® matrix. Bond strength was tested in an universal testing machine (0.5 mm/min). Bond strength means in MPa were: C - E: 18.66 (±2.67) and D: 21.62 (±5.29); PB - E: 18.13 (±2.96) and D: 3.19 (±1.40); SB - E: 20.06 (±6.11) and D: 16.95 (±2.57); AB - E: 18.20 (±3.94) and D: 15.94 (±4.72). Statistical analysis of data by two-way ANOVA showed that C presented the best results followed by SB. In conclusion, among the tested materials, Clearfil Liner Bond 2V self-etching primer adhesive syetem had the best performance. The substrate type influenced bond strength, being higher to enamel.

Este estudo avaliou a resistência à tração de diferentes sistemas adesivos ao esmalte/dentina: Clearfil Liner Bond 2V - C, Prime&Bond NT/NRC - PB, Single Bond -SB and All Bond 2 -AB. Quarenta molares humanos hígidos tiveram suas coroas seccionadas no sentido mesio-lingual, e posteriormente lixadas até que fossem obtidas superfícies lisas de esmalte (E) ou dentina (D). Oitenta espécimes foi aleatoriamente dividido em 4 grupos (n=20, 10 em esmalte e 10 em dentina). Após o tratamento da superfície de acordo com cada sistema adesivo testado, um cone de resina composta Z250 (3M) foi preparado com uma matriz de Teflon®. O teste de tração foi realizado em uma máquina universal de ensaios (0.5 mm/min). As médias de resistência à tração (em MPa) foram: C - E: 18,66 (±2,67) e D: 21,62 (±5,29); PB - E: 18,13 (±2,96) e D: 3,19 (±1,40); SB - E: 20,06 (±6,11) e D: 16,95 (±2,57); AB - E: 18,20 (±3,94) e D: 15,94 (±4,72). A análise estatística (ANOVA a critérios e teste de Tukey) mostrou que C obteve os melhores resultados, seguido por SB. Concluiu-se que, dentre os materiais testados, o Clearfil Liner Bond 2V teve melhor desempenho, e que o tipo de substrato tratado influenciou na resistência adesiva, sendo esta maior em esmalte.