Exploring the potential of rapid maxillary expansion and masticatory muscle activity in unilateral posterior crossbite.

Background: This systematic review and meta-analysis aimed to evaluate if rapid maxillary expansion improves the activity of the masticatory muscles (masseter and temporal) in patients with unilateral posterior crossbite. Material and Methods: Searches were performed in PubMed/MEDLINE, Scopus, Web of Science, Embase, Cochrane Library, and grey literature. A manual search of orthodontic journals was also performed. Randomized clinical trials or longitudinal prospective studies were eligibles. Meta-analyses were conducted using R software with the "Meta" package, applying mean differences with a 95% confidence interval. Risk of bias was assessed using the Newcastle-Ottawa scale, and evidence certainty was evaluated using GRADE. Results: Nine articles were included. Qualitative analysis showed that RME treatment in patients with unilateral posterior crossbite showed a positive correlation with improvement in masseter and temporalis muscle activity. Meta-analyses indicated a significant difference for all models of muscle activity after treatment with rapid maxillary expansion, except for the temporal muscle in the force exerted on the maximum voluntary clenching on cotton rolls. The studies showed low bias risk, and the evidence certainty for each analysis was generally low to very low. Conclusions: This investigation demonstrated the benefits of R rapid maxillary expansion in treating unilateral posterior crossbite and its potential therapeutic effects on the masticatory muscles. Key words:Rapid maxillary expansion, masticatory muscles, unilateral posterior crossbite, systematic review, meta-analysis.

Effect of a novel low-concentration hydrogen peroxide bleaching gel containing nano-sized sodium trimetaphosphate and fluoride.

OBJECTIVES: To evaluate in vitro the effects of nano-sized sodium trimetaphosphate (TMPnano) and sodium fluoride (F) added to a 17.5 % hydrogen peroxide (H2O2) bleaching gel on the color change, enamel mechanical and morphological properties, and H2O2 transamelodentinal diffusion. MATERIALS AND METHODS: Bovine enamel/dentin discs (n = 180) were divided according to the bleaching gel: 17.5 % H2O2 (17.5 % HP); 17.5 % H2O2 + 0.1 % F (HP/F); 17.5 % H2O2 + 1 % TMPnano (HP/TMPnano); 17.5 % H2O2 + 0.1 % F + 1 % TMPnano (HP/F/TMPnano) and 35 % H2O2 (35 % HP). The gels were applied for 40 min on three sessions, each session spaced 7 days apart. The total color change (ΔE*ab) according to the Commission Internationale de l'Eclairage (CIE) L*a*b* color change measured by CIEDE2000 (ΔE00), whitening index (ΔWID), surface hardness (SH), surface roughness (Ra), cross-sectional hardness (ΔKHN), and transamelodentinal diffusion were assessed. Enamel surfaces were examined using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDS) analysis. The data were analyzed using ANOVA, followed by the Student-Newman-Keuls test (p < 0.05). RESULTS: ΔE*ab, ΔE00, and ΔWID values were comparable among the gels that produced a bleaching effect post-treatment (p < 0.001). The HP/F/TMPnano group exhibited lower mineral loss (SH and ΔKHN), Ra, and H2O2 diffusion compared to the 17.5 % HP and 35 % HP groups, which had the highest values (p < 0.001). SEM/EDS analysis revealed surface changes in all bleached groups, though these changes were less pronounced with F/TMPnano. CONCLUSIONS: The 17.5 % HP gel containing F/TMPnano maintains the bleaching effect while reducing enamel demineralization, roughness, H2O2 diffusion, and enamel morphological changes. CLINICAL RELEVANCE: Low-Concentration H2O2 bleaching gel containing F/TMPnano can be used as a novel approach to enhance safety and maintain the performance of aesthetic effects.

The use of mouthwash containing trimetaphosphate as an adjunct therapy to fluoridated toothpaste reduces enamel demineralization.

INTRODUCTION: The decline in dental caries has been attributed to the widespread use of fluoride (F). Two forms of presentation are fluoridated toothpaste (FT) and mouthwash (MW), widely used by the population. MATERIALS AND METHODS: This study aimed to evaluate in vitro the effects of combining FT and MW, whether supplemented with sodium trimetaphosphate (TMP) or not, on dental enamel demineralization. Bovine enamel blocks (n = 60) were selected based on initial surface hardness (SHi) and divided into 5 experimental groups (n = 12 each): I) Placebo Toothpaste (without F/TMP); II) 1100 ppm F Toothpaste (FT); III) 1100F associated with a MW at 100 ppm F (FT + MW 100F); IV) 1100F associated with a MW at 225 ppm F (FT + MW 250F); and V) 1100F associated with a MW at 100 ppm F supplemented with 0.4 % TMP (FT + MW 100F-TMP). The blocks were treated twice a day, undergoing 5 pH cycles over 7 days. Thus, the percentage change in surface hardness (%SH), integrated subsurface hardness loss (ΔKHN), and the concentration of F, phosphorus (P), and calcium (Ca) in the enamel were determined. The data were submitted to ANOVA and Student-Newman-Keuls test (p < 0.001). RESULTS: The 1100F group was statistically inferior to the groups associated with MW for %SH, ΔKHN, and the concentration of P and Ca in the enamel (p < 0.001). Blocks treated with FT + MW 225F and FT + MW 100F-TMP showed significantly lower %SH compared to the other groups (p < 0.001). The FT + MW 100F - TMP group exhibited the lowest depth mineral loss (ΔKHN), and higher concentration de P in enamel (p < 0.001). CONCLUSION: The adjunct use of MW with FT produces a greater protective effect in inhibiting enamel demineralization, and the supplementation of TMP to the MW with 100F provides a superior effect compared to MW with 225F. CLINICAL SIGNIFICANCE: This combination of treatments could be regarded as one of several alternative fluoride supplements for subjects at elevated risk of caries.

Influence of bleaching gels formulated with nano-sized sodium trimetaphosphate and fluoride on the physicochemical, mechanical, and morphological properties of dental enamel.

OBJECTIVES: To evaluate in vitro the effects of sodium fluoride (F) and nano-sized sodium trimetaphosphate (TMPnano) added to a 35% hydrogen peroxide (H2O2) bleaching gel on the color alteration, enamel mechanical and morphological properties, and H2O2 transamelodentinal diffusion. MATERIALS AND METHODS: Bovine enamel/dentin discs (n = 180) were divided according to the bleaching gel: 35% H2O2 (HP); 35% H2O2 + 0.1% F (HP/F); 35% H2O2 + 1% TMPnano (HP/TMPnano); 35% H2O2 + 0.1% F + 1% TMPnano (HP/F/TMPnano) and 35% H2O2 + 2% calcium gluconate (HP/Ca). The gels were applied 3 times by 40 min; once each 7-day. The Commission Internationale de l'Eclairage (CIE) L*a*b* total color alteration (ΔE), color alteration by CIEDE2000 (ΔE00), whitening index (ΔWID), surface (SH) and cross-sectional hardness (ΔKHN), surface roughness (Ra), and transamelodentinal diffusion were determined. Enamel surfaces were evaluated by Scanning Electron Microscopy (SEM) and X-ray Dispersive Energy (EDX). Data were submitted to ANOVA, followed by the Student-Newman-Keuls test (p <0.05). RESULTS: ΔE, ΔE00, and ΔWID were similar among the gels that promoted a bleaching effect after treatment (p <0.001). Mineral loss (SH and ΔKHN), Ra, and H2O2 diffusion were lower for HP/F/TMPnano; the HP and HP/Ca groups presented the highest values (p <0.001). For SEM/EDX, surface changes were observed in all bleached groups, but less intense with TMPnano. CONCLUSIONS: Gels containing F/TMPnano do not interfere with the bleaching effect and reduce enamel demineralization, roughness, H2O2 diffusion, and morphological changes. CLINICAL RELEVANCE: Whitening gels containing F/TMPnano can be used as a new strategy to increase safety and maintain clinical performance.

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.

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.