Stella da Silva Ferreira

In vitro evaluation of the erosive potential of orange juice modified by food additives in enamel and dentine

OBJECTIVES To evaluate the erosive potential of orange juice modified by food additives in enamel and dentine. METHODS Calcium lactate pentahydrate (CLP), xanthan gum (XG), sodium linear polyphosphate (LPP), sodium pyrophosphate tetrabasic (PP), sodium tripolyphosphate (STP) and some of their combinations were added to an orange juice. Pure orange juice and a calcium-modified juice were used as negative (C-) and positive (C+) controls, respectively. In phase 1, 15 modified orange juices were tested for erosive potential using pH-stat analysis. In phase 2, the additives alone and the combination with good results in phase 1 and in previous studies (CLP+LPP) were tested in an erosion-remineralization cycling model. In phase 3, the erosion and remineralization episodes were studied independently. Enamel was analysed by surface microhardness (SMH) and profilometry, whilst dentine by profilometry. RESULTS In phase 1, reduction of the erosive potential was observed for all additives and their combinations, except XG alone. In phase 2, no detectable enamel loss was observed when CLP, LPP and CLP+LPP were added to the juice. XG, STP and PP had enamel loss similar to C- (p>0.05). Amongst additives, the combination CLP+LPP showed the highest SMH values followed by CLP (p<0.05). All the other groups presented SMH values similar to C- (p>0.05). For dentine, only CLP+LPP lead to surface loss values lower than C- (p<0.05). In phase 3, CLP, LPP and CLP+LPP seemed to protect against erosion; whilst none of the tested compounds seemed to interfere with the remineralization process. CONCLUSIONS CLP and LPP reduced erosion on enamel and this effect was enhanced by their combination. For dentine, only the combination CLP+LPP reduced erosion.

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.

The effect of fluoride therapies on the morphology of bleached human dental enamel

The aim of this in vitro study was to evaluate qualitatively the surface morphology of enamel bleached with 35% hydrogen peroxide (HP) followed by application of fluoridated agents. Forty intact pre molars were randomly distributed into four groups (n = 10), treated as follows: Group I (control group) remained stored in artificial saliva at 37°C, Group II ‐ 35% HP; Group III ‐ 35% HP + acidulated fluoride (1.23%) and Group IV ‐ 35% HP + neutral fluoride (2%). The experimental groups received three applications of bleaching gel and after the last application all specimens were polished. This procedure was repeated after 7 and 14 days, and during the intervals of applications, the specimens were stored in artificial saliva at 37°C. Scanning electron microscopy (SEM) analysis showed superficial irregularities and porosities to varying degrees in bleached enamel compared to control group. Sample evaluation was made by attributing scores, and data were statistically analyzed using Kruskal–Wallis and Dunn tests (P < 0.05). SEM qualitative investigation demonstrated that 35% hydrogen peroxide affected human dental enamel morphology, producing porosities, depressions, and superficial irregularities at various degrees. These morphological changes were higher after the application of 1.23% acidulated fluoride gel. Microsc. Res. Tech., 2010.

Development of an orange juice surrogate for the study of dental erosion

The aim of this study was to create a synthetic juice (SJ) to be used as a surrogate for natural orange juices in erosion studies, verifying its erosive potential. The SJ was formulated based on the chemical composition of orange juices from different locations. Forty enamel and 40 root dentin specimens were randomly assigned into 4 experimental groups (n = 10): SJ; 1% Citric Acid (CA); Minute Maid Original® (MM) and Florida Natural Original® (FN). The specimens were immersed in their respective solutions for 5 min, 6x/day for 5 days, in an erosion-remineralization cycling model. Enamel specimens were analyzed by surface Knoop microhardness and optical profilometry and dentin specimens only by optical profilometry. Outcomes were analyzed statistically by ANOVA followed by Tukeys test considering a significance level of 5%. For enamel, the surface loss and microhardness changes found for MM and SJ groups were similar (p>0.05) and significantly lower (p<0.01) than those found in the CA group. For dentin, CA promoted significantly greater (p<0.01) surface loss compared with all the other groups. No significant difference (p>0.05) was observed in dentin surface loss between MM and SJ. In conclusion, CA was the most erosive solution, and SJ had a similar erosive potential to that of MM natural orange juice.

Supplementation of an Orange Juice with Dietary Proteins to Prevent Enamel and Dentin Erosion

Protein supplementation may be an alternative to reduce the erosive potential of acidic drinks. The aim of this in vitro study was to evaluate the erosive potential of an orange juice modified by dietary proteins. A commercially available orange juice was added 0.2 g/L casein, 2.0 g/L ovalbumin and their combination. The juice with no additives and a commercially available calcium-modified juice were used as negative and positive controls, respectively. Human enamel and dentin specimens (n=11) were tested in an erosion-remineralization cycling model. Enamel was analyzed by surface microhardness and profilometry, whilst dentin by profilometry only. Statistical analyses were performed using one-way ANOVA followed by Tukeys test (p<0.05). Calcium-modified juice showed the lowest erosive potential for both analyses (p<0.05). For enamel, the protein-added groups did not differ from each other (p>0.05) and showed significantly lower enamel loss compared to negative control (p<0.05). Regarding surface microhardness, casein showed the highest values compared to negative control (p<0.05). For dentin, none of the protein-added groups showed lower values of surface loss compared to negative control (p>0.05). In conclusion, for enamel the protein-modified orange juices presented reduced erosion of enamel, with casein showing a trend for better protection. For dentin, no reduction in the erosive potential was observed for the tested protein-modified orange juices.