In vitro Evaluation of Surface Free Energy of Dentin after Treatment with Sodium Trimetaphosphate Associated or Not with Fluoride, Exposed or Not to Calcium.

It has been stated that sodium trimetaphosphate (TMP) promotes a more anionic dentin surface inducing greater calcium (Ca) and phosphate precipitation. The aim of the present study was to evaluate in vitro the surface free energy (γs) of dentin after treatment with TMP associated or not with fluoride (F), exposed or not to Ca, as well as the adsorption of TMP, F, and Ca by dentin. Bovine dentin blocks (n = 12 blocks/group) were treated with solutions containing TMP at 0, 1, 3, or 9 (w/v) followed or not by the application of Ca. These solutions were or were not associated to 1,100 ppm F. F, Ca, and TMP were determined in the solutions before and after the treatment to calculate the adsorption by dentin. To analyze the γs of dentin, the apolar (γsLW), and polar (γsAB), components were determined by contact angle measurement. Data were submitted to 2-way ANOVA followed by the Student-Newman-Keuls test (p < 0.05). TMP reduces γs of dentin and increases electron donor sites (γs-). Higher values of γs- led to higher adsorption of Ca (p < 0.001). The F/TMP association did not change γs or γsLW and reduced the values of γs-, but the adsorption of Ca was higher. There was correlation between the adsorption of TMP and γs- (Pearson's r = 0.801; p < 0.001) and F (Pearson's r = 0.871, p < 0.001). It is possible to conclude that TMP increased γs- and Ca adsorption, and reduced γs. The association with F increased the adsorption of TMP without rising γs-; however, there was higher adsorption of Ca.

The effect of toothpaste with reduced concentration of fluoride-containing sodium trimetaphosphate and polyols on initial enamel erosion.

OBJECTIVES: This in vitro study evaluated the efficacy of toothpaste containing fluoride (F), sodium trimetaphosphate (TMP), and xylitol and erythritol (XE) to inhibit or repair initial enamel erosion lesions. MATERIALS AND METHODS: Bovine enamel blocks (n = 120) were selected according to surface hardness (SH) and randomly divided into 5 experimental groups (n = 24 blocks/group): Placebo (no F, TMP, XE); 1100 ppm F; 16% xylitol + 4% erythritol (XE); 200 ppm F + 0.2% TMP (200 ppm F/TMP); and 200 ppm F + 0.2% TMP + 16% xylitol + 4% erythritol (200 ppm F/TMP/XE). The sound and softened blocks were immersed in toothpaste slurry in human saliva for 2 min. The blocks were then submitted to 4 erosive challenges in citric acid (0.75%, pH 3.5), each challenge for 1 min, with stirring. The SH of the blocks was determined after treatment (t) and after the 4 erosive challenges. In addition, the precipitates were analyzed by scanning electron microscopy (SEM). Variables were submitted to a two-way repeated-measures analysis of variance followed by a Student-Newman-Keuls test (p < 0.05). RESULTS: Toothpaste containing 200 ppm F/TMP/XE led to the highest protective and repair effect compared to the other groups (p < 0.001). The protective and repair effect was XE > 200 ppm F/TMP > 1100 ppm F > placebo (p < 0.001). All groups produced precipitates with a thicker layer for XE and TMP groups. CONCLUSIONS: Toothpaste containing 200 ppm F, TMP, and polyols demonstrated a superior protective and repair effect in initial enamel erosive lesions in vitro. CLINICAL RELEVANCE: Toothpaste containing F and polyols could be an advantage in patients affected by dental erosion, due to its higher preventive potential, mainly in individuals who frequently drink acidic beverages. However, future studies are needed to confirm these results.

Hydraulic conductance of dentin after treatment with fluoride toothpaste containing sodium trimetaphosphate microparticles or nanoparticles.

OBJECTIVES: To evaluate the hydraulic conductance of dentin after treatment with fluoride toothpastes containing sodium trimetaphosphate microparticles (TMPmicro) or nanoparticles (TMPnano). MATERIALS AND METHODS: The dentinal tubules of bovine dentin blocks (4 × 4 × 1 mm) were unobstructed for determination of the maximum hydraulic conductance of the dentin. The dentin blocks were randomized into four groups (n = 15/group) of toothpastes (placebo, 1100 ppm F, and 1100 with 3% TMPmicro or 3% TMPnano) which were applied for 7 days (2×/day) using a brushing machine. The dentin surface (5/group) was analyzed by scanning electron microscopy. The hydraulic conductance post-treatment was measured in the other ten blocks. Thereafter, the same blocks were immersed in citric acid (pH 3.2) for 1 min, and the conductance was determined again. The data were submitted to 2-way ANOVA repeated measures, followed by the Student-Newman-Keuls test (p < 0.05). RESULTS: The percentage conductance reduction post-treatment for the groups were placebo = 1100 ppm F < 1100 TMPnano < 1100 TMPmicro (p < 0.001). After acid attack, the percentage reduction was placebo < 1100 ppm F < 1100 TMPnano < 1100 TMPmicro (p < 0.001). The toothpastes containing TMP showed the highest obliteration of dentinal tubules. CONCLUSIONS: The addition of TMPmicro to fluoride toothpaste produced a greater reduction in hydraulic conductance when compared with 1100 ppm F toothpaste. CLINICAL RELEVANCE: The increased capacity of toothpastes containing TMP to reduce hydraulic conductance indicates their potential to reduce symptoms of dentinal hypersensitivity.

Ion release, antimicrobial and physio-mechanical properties of glass ionomer cement containing micro or nanosized hexametaphosphate, and their effect on enamel demineralization.

OBJECTIVES: To evaluate the effects of hexametaphosphate microparticles (mHMP) or nanoparticles (nHMP) incorporated in glass ionomer cement (GIC) on antimicrobial and physico-mechanical properties, fluoride (F) release, and enamel demineralization. MATERIAL AND METHODS: HMP solutions were obtained at concentrations of 1, 3, 6, 9, and 12%, for screening of antimicrobial activity. Next, mHMP or nHMP at 6, 9, and 12% were incorporated into a resin-modified GIC and the antibacterial activity was evaluated. The resistance to diametral tensile and compressive strength, surface hardness, and degree of monomer conversion as well as F and HMP releases of GICs were determined. Furthermore, specimens were attached to enamel blocks and submitted to pH-cycling, and mineral loss was determined. Parametric and non-parametric tests were performed, after checking data homoscedasticity (p < 0.05). RESULTS: HMP solutions at 6, 9, and 12% demonstrated the best antibacterial activity. GIC containing HMP showed better antibacterial effects at 9 and 12% for nHMP. Regarding F and HMP releases, the highest levels of release occurred for groups containing 9 and 12% nHMP. With the increase in HMP concentration, there was lower mineral loss. However, the incorporation of mHMP or nHMP in GIC reduced values of physico-mechanical properties when compared to the control GIC. CONCLUSIONS: nHMP improves antimicrobial activity and fluoride release, and decreases enamel demineralization, but reduces the physico-mechanical properties of GIC. CLINICAL RELEVANCE: The association of GIC/HMP could be an alternative material for patients at high risk for dental caries and could be indicated for low-stress regions or provisional restorations.

Dentinal tubule obliteration using toothpastes containing sodium trimetaphosphate microparticles or nanoparticles.

OBJECTIVES: This in vitro study evaluated the effect of microparticles (TMPmicro) or nanoparticles (TMPnano) TMP associated with fluoride (F) in toothpaste formulations on the obliteration of dentinal tubules (DT). MATERIALS AND METHODS: The dentinal tubules of bovine dentin blocks were unobstructed by immersion in 37% phosphoric acid solution. Blocks (n = 20/group) underwent mechanical brushing (2×/day) during 7 days with toothpastes: placebo, 1100 ppm F, and 1100 with 3% TMPmicro or 3% TMPnano. After that, ten blocks of each group were immersed in citric acid (pH 3.2) for 1 min. The number, diameter and area of unobstructed DT, atomic % of chemical elements from precipitates, and the mineral concentration were quantified. Data were submitted to two-way ANOVA, followed by Student-Newman-Keuls test (P < 0.05). RESULTS: Toothpastes containing TMPmicro and TMPnano promoted greater obliteration of DT and greater mineral concentration compared to other groups (P < 0.05). Placebo and 1100 ppm F group presented similar obliteration but 1100 ppm F group promoted higher mineral concentration. Higher Ca/P ratios were observed in groups treated with TMP; the acid challenge reduced Ca/P ratio for all groups. The atomic % of C and N was significantly lower for TMP toothpastes before acid challenge, but increased afterwards. CONCLUSIONS: It was concluded that the addition of TMPmicro or TMPnano to F toothpastes produced greater obliteration of dentinal tubules and higher mineral concentration when compared with 1100 ppm F. CLINICAL RELEVANCE: By the addition of TMP, fluoride toothpastes may occlude the dentinal tubules, with potential to reduce dentin hypersensitivity.

In vitro enamel remineralization capacity of composite resins containing sodium trimetaphosphate and fluoride.

OBJECTIVES: This study evaluated the in vitro enamel remineralization capacity of experimental composite resins containing sodium trimetaphosphate (TMP) combined or not with fluoride (F). MATERIALS AND METHODS: Bovine enamel slabs were selected upon analysis of initial surface hardness (SH1) and after induction of artificial carious lesions (SH2). Experimental resins were as follows: resin C (control­no sodium fluoride (NaF) or TMP), resin F (with 1.6% NaF), resin TMP (with 14.1% TMP), and resin TMP/F (with NaF and TMP). Resin samples were made and attached to enamel slabs (n = 12 slabs per material). Those specimens (resin/enamel slab) were subjected to pH cycling to promote remineralization, and then final surface hardness (SH3) was measured to calculate the percentage of surface hardness recovery (%SH). The integrated recovery of subsurface hardness (ΔKHN) and F concentration in enamel were also determined. Data was analyzed by ANOVA and Student-Newman-Keuls test (p < 0.05). RESULTS: Resins F and TMP/F showed similar SH3 values (p = 0.478) and %SH (p = 0.336) and differed significantly from the other resins (p < 0.001). Considering ΔKHN values, resin TMP/F presented the lowest area of lesion (p < 0.001). The presence of F on enamel was different among the fluoridated resins (p = 0.042), but higher than in the other resins (p < 0.001). CONCLUSIONS: The addition of TMP to a fluoridated composite resin enhanced its capacity for remineralization of enamel in vitro. CLINICAL RELEVANCE: The combination of two agents with action on enamel favored remineralization, suggesting that composite resins containing sodium trimetaphosphate and fluoride could be indicated for clinical procedures in situations with higher cariogenic challenges.

Delayed tooth replantation in rats: effect of systemic antibiotic therapy with amoxicillin and tetracycline.

Systemic antibiotic therapy (SAT) has usually been recommended after tooth replantation, but its actual value has been questioned. As there are no reports in the literature about its influence on tooth replantation, the aim of this study was to evaluate the influence of systemic administration of antibiotics (amoxicillin and tetracycline) at the different phases of the repair process (7, 15, 30 days) in delayed rat tooth replantation. Ninety Wistar rats (Rattus norvegicus albinus) had their maxillary right incisors extracted and bench-dried for 60 min. The dental papilla, enamel organ, pulp tissue, and root surface-adhered periodontal ligament were removed, and the teeth were replanted. The animals received no antibiotics (n = 30) or were medicated systemically with amoxicillin (n = 30) and tetracycline (n = 30), and were euthanized after 7, 15, and 30 days. Regardless of the evaluation period, the acute inflammatory infiltrate was less intense and root resorption presented smaller extent and depth in the group treated with amoxicillin. The results suggest that SAT has a positive influence on the repair process in delayed tooth replantation and that amoxicillin is an excellent treatment option.

Evaluation of the radiopacity of esthetic root canal posts.

UNLABELLED: The radiopacity of esthetic root canal posts may impair the assessment of their fit to the root canal when using radiographic images. This study determined in vitro the radiographic density of esthetic root canal posts using digital images. Thirty-six roots of human maxillary canines were assigned to six groups (N=6 per group): Reforpost (RP); Aestheti-Plus (AP); Reforpost MIX (RPM); D.T. Light Post (LP); Reforpost Radiopaque (RPR); and White Post DC (WP). Standardized digital images of the posts were obtained in different conditions: outside the root canal, inside the canal before and after cementation using luting material, and with a tissue simulator. Analysis of variance was used to compare the radiopacity mean values among the posts outside the root canal and among the posts under the other conditions, and the "t" unpaired test to compare the radiopacity between the posts and the dentin, and between the posts and the root canal space. There was no statistically significant difference in radiopacity between RP and RPM, and LP and WP. AP posts showed radiopacity values significantly lower than those for dentin. No statistically significant difference was found between posts (RP and AP) and the root canal space. A statistically significant difference was observed between the luted and non-luted posts; additionally, luted posts with and without tissue simulator showed no significant differences. Most of the cement-luted posts analyzed in this study were distinguishable from the density of adjacent dentin surfaces, allowing radiographic confirmation of the fit of the post in the canal. CLINICAL SIGNIFICANCE: The success of using esthetic root canal posts depends mainly on the fit of the post within the canal.[1] The radiopacity of a post allows for radiographic imaging to be used to determine the fit, an important factor in a clinical perspective.

Effect of resin composites with sodium trimetaphosphate with or without fluoride on hardness, ion release and enamel demineralization.

PURPOSE: To evaluate the effect of the addition of sodium trimetaphosphate (TMP) with or without fluoride on enamel demineralization, and the hardness and release of fluoride and TMP of resin composites. METHODS: Bovine enamel slabs (4 x 3 x 3 mm) were prepared and selected based on initial surface hardness (n = 96). Eight experimental resin composites were formulated, according to the combination of TMP and sodium fluoride (NaF): TMP/NaF-free (control), 1.6% sodium fluoride (NaF), and 1.5%, 14.1% and 36.8% TMP with and without 1.6% NaF. Resin composite specimens (n = 24) were attached to the enamel slabs with wax and the sets were subjected to pH cycling. Next, surface and cross-sectional hardness and fluoride content of enamel as well as fluoride and TMP release and hardness of the materials were evaluated. Data were statistically analyzed using ANOVA (P < 0.05). RESULTS: The presence of fluoride in enamel was similar in fluoridated resin composites (P > 0.05), but higher than in the other materials (P < 0.05). The combination of 14.1% TMP and fluoride resulted in less demineralization, especially on lesion surface (P < 0.05). The presence of TMP increased fluoride release from the materials and reduced their hardness.

Biochemical and microbiological characteristics of in situ biofilm formed on materials containing fluoride or amorphous calcium phosphate.

PURPOSE: To evaluate the biochemical and microbiological characteristics of in situ biofilm formed on materials that release fluoride (F-) or calcium (Ca++) and phosphate (Pi). METHODS: This study comprised an in situ and in vitro experiment, utilizing three materials [Auralay XF and Fuji IX GP, containing fluoride, and Aegis containing amorphous calcium phosphate (ACP)] and bovine dental enamel slabs. For the in situ: 10 volunteers wore palatal devices, each containing four material specimens or enamel slabs that were treated with 20% sucrose solution. The biofilm had pH measurements on Day 7 and the composition was analyzed on Day 8 by assessing the following: F-, Ca++, Pi and insoluble extracellular polysaccharides (EPS) concentrations, and then identification of the microbiota. For the in vitro: materials/enamel were subjected to a 7-day pH-cycling regimen to determine F, Ca++ and Pi release. RESULTS: The biofilm formed on F(-)-releasing materials was richer in F, Ca++ and Pi and had lower mutans streptococci counts than enamel biofilm. The biofilm on the ACP-containing material exhibited similar Ca++ and Pi concentrations to biofilm on F(-)-releasing materials. The materials showed buffering action compared with enamel. Biochemical and microbiological characteristics showed a less cariogenic biofilm on materials containing fluoride or amorphous calcium phosphate.

Histological and immunohistochemical analyses of the chronology of healing process after immediate tooth replantation in incisor rat teeth.

Dental tissues have special characteristics, and its regenerative capacity is noteworthy. However, understanding the circumstances that lead to regeneration is challenging. In this study, the chronology of the healing process after immediate replantation of rat incisor teeth was examined by histological and immunohistochemical analyses within a 60-day period. Thirty-six male Wistar rats had their maxillary right incisors extracted and replanted after 15 min in saline storage. The rats were sacrificed immediately 3, 7, 15, 28, and 60 days after replantation. The histological analysis showed rupture of the periodontal ligament and formation of a blood clot, which started being replaced by a connective tissue after 3 days. At 7 days, the gingival mucosa epithelium was reinserted and areas of root resorption could be seen. At 15 days, the periodontal ligament was repaired. At 3 days, the pulp presented an absence of the odontoblast layer, which started being replaced by a connective tissue. This tissue suffered gradual calcification, filling the root canal at 28 and 60 days. The root ends were closed. The immunohistochemical analysis revealed greater expression of OP, OPG, and RANK proteins in the initial periods (0 and 3 days), while TRAP expression predominated at 28 and 60 days (P < 0.05). In conclusion, in delayed tooth replantation, there is great new bone formation activity in the earlier periods of the repair process, while a predominance of bone resorption and remodeling is observed in the more advanced periods.

Clinical evaluation of the association between noncarious cervical lesions and occlusal forces.

STATEMENT OF PROBLEM: Noncarious cervical lesions (NCCLs) are a frequent challenge in clinical dental practice, given the variety of opinions regarding their etiology, diagnosis, and treatment. PURPOSE: The purpose of this study was to assess the potential relationship between occlusal forces and the occurrence of NCCLs. MATERIAL AND METHODS: The participant population consisted of 111 volunteers (30 male and 81 female, mean age 23.6 years). General personal information was recorded, after which participants were examined for the presence and location of NCCLs, gingival recession, fracture lines, dental and restoration fractures, presence and location of tooth wear, type of occlusal guidance scheme for lateral mandibular movements, and existence of occlusal interference or premature contacts. The participants were divided according to the presence or absence of NCCLs, and data were statistically analyzed with the Independent t test, the Chi-square test, and the Fisher exact test (α=.05). RESULTS: A significant association was found between the presence of NCCLs and age (P=.008), gingival recession (P<.001), occlusal trauma (P<.001), presence (P<.001) and location of tooth wear, and group function as occlusal guidance scheme in lateral excursive movements (P<.001). CONCLUSIONS: A strong relationship between the presence of NCCLs and occlusal overload was found.

Effect of adrenaline and noradrenaline on biofilm formation and virulence factors of Streptococcus mutans UA159.

OBJECTIVES: To evaluate in vitro the effects of adrenaline and noradrenaline on the biofilm formation on orthodontic brackets, acid production and expression of virulence genes of Streptococcus mutans UA159 (S. mutans). DESIGN: S. mutans UA159 biofilm was formed on orthodontic brackets under exposure to adrenaline (100 µM), noradrenaline (50 µM) or PBS solution (control group) in triptone-yeast extract with 1 % sucrose. After 24 h, biofilm formation was quantified through Colony Forming Units / mL (CFU/mL) and RNA was extracted to perform gene expression analysis through real-time reverse transcriptase-PCR (RT-qPCR). Evaluation of acid production was carried out on planktonic cultures for 6 h. One-way ANOVA followed by Tukey's test was carried to determine statistical difference. The level of significance was set at 5 %. RESULTS: Catecholamines stimulated biofilm formation of S. mutans in orthodontic brackets (p < 0,05) but did not interfere with acid production (pH reduction) or the expression of the tested genes related to biofilm formation (gtfB, gtfC, gbpA, gbpB, gbpC, gbpD and brpA), aciduric (relA) and acidogenic properties (ldh). CONCLUSIONS: The present study was the first to demonstrate that catecholamines can stimulate S. mutans UA159 biofilm formation. These findings can contribute to clarify the role of stress on bacterial metabolism and contribute to the understanding of a possible role on caries development, mainly in orthodontic patients.

In situ evaluation of the remineralizing capacity of pit and fissure sealants containing amorphous calcium phosphate and/or fluoride.

OBJECTIVE: This in situ study evaluated the remineralizing potential of pit and fissure sealants containing amorphous calcium phosphate (ACP) and/or fluoride in artificially induced carious lesions on smooth enamel surfaces. MATERIAL AND METHODS: Ten volunteers who wore acrylic palatal devices were enrolled in this 5-day double-blind study and assigned to one of the following five groups: (I) demineralized enamel slab+Fluroshield (sealant with fluoride); (II) demineralized enamel slab+Aegis (sealant with ACP); (III) demineralized enamel slab+experimental sealant with fluoride (ESF); (IV) demineralized enamel slab+experimental sealant with fluoride/ACP (ACP-F); and (V) demineralized enamel slab (control). After the experimental period, the percentage of surface microhardness recovery (%SMHR) and the integrated loss of subsurface hardness (DeltaKHN) were evaluated. The concentrations of fluoride, calcium and phosphorus in enamel were also determined. RESULTS: The sealants containing ACP and/or fluoride presented a higher remineralizing capacity (%SMHR and DeltaKHN) than that of the control group. Aegis provided either more efficient or similar remineralization than the other sealants. The association between ACP and fluoride did not show a greater efficacy in the remineralization. F, Ca and P concentrations in enamel varied according to the group. CONCLUSION: The pit and fissure sealants containing ACP were able to promote remineralization of artificially induced carious lesions on smooth enamel surfaces.

Incorporation of chlorhexidine and nano-sized sodium trimetaphosphate into a glass-ionomer cement: Effect on mechanical and microbiological properties and inhibition of enamel demineralization.

OBJECTIVE: To evaluate the antimicrobial/antibiofilm and mechanical properties, and the effect on enamel demineralization of a resin-modified GIC (RMGIC) containing CHX and nano-sized sodium trimetaphosphate (TMP). METHODS: RMGIC was associated with CHX (1.25 or 2.5%) and/or TMP (7 or 14%). Antimicrobial and antibiofilm activity were assessed using agar diffusion test and evaluation of biofilm metabolism, respectively. In addition, fluoride (F) and TMP releases as well as the diametral tensile (DTS) and compressive (CS) strength were determined. The percentage of mineral loss (%SH), integrated loss of subsurface hardness (ΔKHN) and enamel F concentrations were also evaluated. RESULTS: RMGICs containing CHX associated or not with TMP presented higher inhibition zones and effect on S. mutans biofilm. A reduction on CS was observed only for RMGIC + 2.5%CHX and on DTS for RMGIC + 2.5%CHX + 14%TMP. The highest F and TMP releases and lowest %SH and ΔKHN values were detected for RMGIC + 1.25%CHX + 14%TMP and RMGIC + 2.5%CHX + 14%TMP. Higher enamel F concentrations were observed for TMP groups. CONCLUSION: 1.25%CHX and 14%TMP increased antimicrobial/antibiofilm action and the ability to prevent enamel demineralization, with minimal effect on the mechanical properties of RMGIC. CLINICAL SIGNIFICANCE: RMGIC containing CHX and TMP is an alternative material for patients at high risk for dental caries and can be indicated for low-stress regions or provisional restorations.

Resin-modified glass ionomer containing calcium glycerophosphate: physico-mechanical properties and enamel demineralization.

BACKGROUND: Sources of calcium and phosphate have been added to dental restorative materials to improve their anticaries effect. OBJECTIVE: This study evaluated the effect of adding calcium glycerophosphate (CaGP) to resin-modified glass ionomer cement (RMGIC) on the physico-mechanical properties, ion release, and enamel demineralization. Material and Methods: Specimens were fabricated for each experimental group: RMGIC without CaGP (Control), RMGIC with 1, 3 and 9% CaGP. To determine the release of fluoride (F), calcium (Ca) and phosphorus (P), six specimens were immersed in demineralization and remineralization solutions for 15 days. In another experimental trial, the following physico-mechanical properties were evaluated at time intervals of 1 and 7 days after fabrication: compressive strength (n=12), diametral tensile strength (n=12), surface hardness of material (n=6) and the degree of conversion of monomers (n=8). To study enamel demineralization, specimens (n=12) were attached to enamel blocks and submitted to pH-cycling. Subsequently, surface and cross-sectional hardness and the concentration of F, Ca and P in enamel were determined. RESULTS: The addition of CaGP to RMGIC led to higher mean release of F, Ca and P when compared with control (p<0.001). Mechanical properties were within the range of those of the ionomer cements after addition of 1% and 3% CaGP. The degree of conversion did not differ between groups at the 1st and the 7th day (p>0.439). The addition of 3% and 9% CaGP reduced mineral loss and increased F, Ca and P in the enamel when compared with control (p<0.05). CONCLUSION: The addition of 3% CaGP in RMGIC increased the release of F, P and Ca, reduced enamel demineralization, and maintained the physico-mechanical properties within the parameters for this material.

PH-cycling model to verify the efficacy of fluoride-releasing materials in enamel demineralization.

The current study proposes a pH-cycling model to verify the dose-response relationship of fluoride-releasing materials in their ability to reduce in vitro demineralization. Sixty bovine enamel blocks (4 x 3 x 3 mm) were selected, using baseline surface microhardness (SMH1) evaluations at different distances from the enamel sectioned border (150, 300, 450 and 600 microm). Specimens (n=48) were prepared with Z100, Fluroshield and Vitremer at the standard powder/liquid ratio and at a 1/4 diluted-powder/liquid ratio. The 12 remaining specimens were used as a control group. The specimens were submitted to a pH-cycling model with high cariogenic challenge. After pH-cycling, final surface microhardness (SMH2) was assessed to calculate the percentage change of surface microhardness (%SMHc). Next, the fluoride present in enamel (microg F/mm3) and in pH-cycling solutions (microg F) was measured. Cross-sectional microhardness was done to calculate the mineral content (deltaZ). Data from %SMHc, deltaZ and microg F were analyzed by analysis of variance (p < 0.05), while microg F/mm3 analysis was done using the Kruskal-Wallis test. The results showed a correlation between %SMHc and microg F/mm3 (r3 = 0.4129; p < 0.0001), %SMHc and microg F (r2 = 0.4932; p < 0.0001), deltaZ and microg F/mm3 (r3 = 0.4573; p < 0.0001), micorg F/mm3 and microg F (r2 = 0.3029; p < 0.0001) and between deltaZ and microg F (r2 = 0.5276; p < 0.0001). The pH-cycling model allowed the in vitro verification of the dose-response relationship of fluoride-releasing materials in the demineralization of enamel.

Treatment of root surface in delayed tooth replantation: a review of literature.

The time elapsed between a trauma and tooth replantation usually ranges from 1 to 4 h. The chances of root surface damage are higher when tooth replantation is not performed immediately or if the avulsed tooth is not stored in an adequate medium. This invariably leads to necrosis of pulp tissue, periodontal ligament cells and cementum, thus increasing the possibility of root resorption, which is the main cause of loss of replanted teeth. This paper presents a comprehensive review of literature on root surface treatments performed in cases of delayed tooth replantation with necrotic cemental periodontal ligament. Journal articles retrieved from PubMed/MedLine, Bireme and Scielo databases were reviewed. It was observed that, when there are no periodontal ligament remnants and contamination is under control, replacement resorption and ankylosis are the best results and that, although these events will end up leading to tooth loss, this will happen slowly with no loss of the alveolar ridge height, which is important for future prosthesis planning.

Evaluation of cases of concussion and subluxation in the permanent dentition: a retrospective study.

Objectives This study evaluated the evolution of cases of concussion and subluxation through a retrospective study of 20 years. Material and Methods Were examined clinical and radiographic records of 1,309 patients who underwent treatment of dentoalveolar trauma in the discipline of Integrated Clinic of the School of Dentistry of Araçatuba, UNESP, of which we selected 137 whose patients had concussion and subluxation injuries, with average age of 23.3 (SD - 10.96). The variables collected were: gender, age, history of previous and actual trauma, treatments performed, the presence of necrotic pulp, and time elapsed until the same trauma. The concussion and subluxation groups were subjected to statistical analyses using the SPSS 16.0 version software (α=0.05), Chi-square, and t-tests. Results Of the 301 teeth involved, 49 (16.3%) suffered concussion and 252 (83.7%), subluxation, being the upper anterior teeth the most affected (75.1%) for both conditions. Subluxation and concussion traumas were more prevalent in men aged 10 to 20 years, most caused by cycling accidents (36.2%). There was a concomitant presence of crown fracture in 21% of cases of concussion and 34.7% of subluxation. Pulp necrosis was detected in 16.3% (concussion) and 27.1% (subluxation) (p=0.12), and most occurred within 6 months after the trauma (p=0.29). The pulp necrosis shows a positive correlation with motorcycle accidents (p=0.01), direct impact (p≤0.0001), crown fracture with pulp exposure (p≤0.0001), darkening of the crown (p=0.004) and spontaneous pain (p≤0.0001); and negative correlation with indirect impact (p≤0.0001). Conclusions Although concussion and subluxation traumas are considered of minor degrees, they must be monitored, since the possibility of pulp necrosis exists, and its early treatment favors a good prognosis.

Effect of pH variations in a cycling model on the properties of restorative materials.

This study evaluated the effect of cycling various pH demineralizing solutions on the surface hardness, fluoride release and surface properties of restorative materials (Ketac-Fil Plus, Vitremer, Fuji II LC, Freedom and Fluorofil). Thirty specimens of each material were made and the surface hardness measured. The specimens were randomized into five groups according to the pH (4.3; 4.6; 5.0; 5.5 and 6.2) of the demineralizing solution. The specimens were submitted to pH-cycling for 15 days. The specimens remained in the demineralizing solution for six hours and in the remineralizing solution for 18 hours. Then, the surface hardness (SH) was remeasured and the surface properties were assessed. Fluoride release was determined daily. Data from SH and the percentage of alteration in surface hardness were analyzed by analysis of variance (p < 0.05); the Kruskal-Wallis test was performed for the fluoride release results. When hardness was compared, the variation in pH led to a positive correlation for glass ionomer cements and a negative correlation for fluoride release. For polyacid-modified resin composites, a negative correlation was found with regards to fluoride release; no significant correlation was observed for hardness. Surface properties were influenced: an acidic pH led to a greater alteration, except for polyacid-modified resin composites. The pH of the demineralizing solution influenced fluoride release from the tested materials. The pH variation altered hardness and surface properties of glass ionomer cements but did not influence polyacid-modified resin composites.