Root canal curvature influences uncontrolled removal of dentin and cleaning efficacy after ultrasonic activation.

This study evaluated the correlation between root canal curvature and the effects of ultrasonic irrigation in the following parameters: volume of uncontrolled dentin removal (UDRVol), maximum depth of dentin defects, removal of accumulated hard tissue debris (AHTD), and canal transportation in prepared curved root canals. Twenty-four human permanent mandibular molars were divided into two groups according to root canal curvature: moderate curvature (MC: mean 25°); and severe curvature (SC: mean 48°). The specimens were scanned using an X-ray microcomputed scanner (Skyscan 1172) before and after cleaning and shaping and after the final irrigation protocol with ultrasonic irrigation. There was a moderate correlation between the degree of root canal curvature and the volume of remaining AHTD (p<0.05) and between the degree of root canal curvature and maximum depth of defects due to uncontrolled removal of dentin (p<0.05). The teeth in the SC group had a greater maximum depth of defects on the dentin wall in the apical third than the teeth in the MC group (p <0.05). Both groups had a significant reduction of AHTD in all canal thirds, but the amount of remaining AHTD in the middle and apical thirds and the whole canal was significantly greater in the SC than in the MC group (p <0.05). Canal transportation was not influenced by the canal curvature in all thirds (p >0.05). This study concluded that root canal curvature affects significantly the uncontrolled removal of dentin and remaining AHTD volume after the final irrigation protocol with ultrasonic irrigation.

Root canal curvature influences uncontrolled removal of dentin and cleaning efficacy after ultrasonic activation

Abstract This study evaluated the correlation between root canal curvature and the effects of ultrasonic irrigation in the following parameters: volume of uncontrolled dentin removal (UDRVol), maximum depth of dentin defects, removal of accumulated hard tissue debris (AHTD), and canal transportation in prepared curved root canals. Twenty-four human permanent mandibular molars were divided into two groups according to root canal curvature: moderate curvature (MC: mean 25°); and severe curvature (SC: mean 48°). The specimens were scanned using an X-ray microcomputed scanner (Skyscan 1172) before and after cleaning and shaping and after the final irrigation protocol with ultrasonic irrigation. There was a moderate correlation between the degree of root canal curvature and the volume of remaining AHTD (p<0.05) and between the degree of root canal curvature and maximum depth of defects due to uncontrolled removal of dentin (p<0.05). The teeth in the SC group had a greater maximum depth of defects on the dentin wall in the apical third than the teeth in the MC group (p <0.05). Both groups had a significant reduction of AHTD in all canal thirds, but the amount of remaining AHTD in the middle and apical thirds and the whole canal was significantly greater in the SC than in the MC group (p <0.05). Canal transportation was not influenced by the canal curvature in all thirds (p >0.05). This study concluded that root canal curvature affects significantly the uncontrolled removal of dentin and remaining AHTD volume after the final irrigation protocol with ultrasonic irrigation.

Resumo Este estudo avaliou a correlação entre a curvatura do canal radicular e os efeitos da irrigação ultrassônica nos seguintes parâmetros: volume de remoção não controlada de dentina (UDRVol), profundidade máxima do desgaste de dentina, remoção de debris de tecido duro acumulado (AHTD) e transporte em canais radiculares curvos. Vinte e quatro molares inferiores humanos permanentes foram divididos em dois grupos de acordo com a curvatura do canal radicular: curvatura moderada (MC: média de 25°); e curvatura acentuada (SC: média de 48°). Os espécimes foram digitalizados usando um scanner microcomputador de raios X (Skyscan 1172) antes e depois da limpeza e modelagem e após a irrigação ultrassônica. Houve uma correlação moderada entre o grau de curvatura do canal radicular e o volume de AHTD remanescente (p<0,05) e entre o grau de curvatura do canal radicular e a profundidade máxima de defeitos devido à remoção descontrolada de dentina (p<0,05). Os dentes do grupo SC apresentaram maior profundidade máxima de defeitos na parede dentinária no terço apical do que os dentes do grupo MC (p<0,05). Ambos os grupos tiveram uma redução significativa de AHTD em todos os terços do canal, mas a quantidade de AHTD remanescente nos terços médio e apical e em todo o canal foi significativamente maior no grupo SC do que no grupo MC (p <0,05). O transporte do canal não foi influenciado pela curvatura do canal em todos os terços (p > 0,05). Este estudo concluiu que a curvatura do canal radicular afeta significativamente a remoção descontrolada de dentina e o volume remanescente de AHTD após a irrigação ultrassônica.

Fluorotic Enamel Susceptibility to Dental Erosion and Fluoride Treatment.

The purpose of this in vitro study was to test the hypothesis that fluoride treatment can prevent dental erosion on fluorotic enamel of different severities. It followed a 3×2 factorial design, considering a) fluorosis severity: sound (TF0, Thylstrup-Fejerskov Index), mild (TF1-2), moderate (TF3-4); and b) fluoride treatment: 0 (negative control) and 1150ppmF. Human molars with the three fluorosis severities (n=16, each) were selected and randomly assigned to the two fluoride treatments (n=8). Enamel blocks (4×4mm) were prepared from each tooth and subjected to a dental erosion cycling model, for 10 days. The daily cycling protocol consisted of erosive challenges (1% citric acid, pH 2.4), interspersed by periods of immersion in artificial saliva, and three 2-minute treatments with either 0 or 1150ppm F. The enamel volume loss (mm3) was calculated by subtracting values obtained by microtomography before and after cycling. Two-Way ANOVA showed no significant interaction between fluorosis severity and fluoride treatment (p=0.691), and no significant effect for either fluorosis severity (TF0 mean±standard-deviation: 13.5(10-2±0.42(10-2, TF1-2: 1.50(10-2±0.52(10-2, TF3-4: 1.24(10-2±0.52(10-2, p=0.416) or treatment (0ppmF: 1.49(10-2±0.53(10-2; 1150ppmF: 1.21(10-2±0.42(10-2; p=0.093), when evaluated independently. Considering the limitations of this in vitro study, the presence and severity of fluorosis in enamel do not appear to affect its susceptibility to dental erosion. Fluoride treatment was not effective in preventing the development of dental erosion in both sound and fluorotic enamel substrates under our experimental conditions.

Zoledronate treatment exerts sex-independent effects on bone and dental physicochemical properties in mice jaw necrosis.

INTRODUCTION: Bisphosphonate (BF) therapy is strongly related to the occurrence of medication-related osteonecrosis of the jaw (ONJ). However, no previous study has evaluated if there are sex-related differences on the ONJ establishment together with bone biomechanical alterations, and if they could have a synergy with the ZA treatment. MATERIALS AND METHODS: This study aimed to analyze the physicochemical properties of mineralized tissues in a zoledronate (ZA)-related osteonecrosis mouse model, by a 2 × 2-factorial design, considering sex (female/male) and treatment (ZA/Saline) factors (n = 8/group). After three ZA (1.0 mg/kg) or saline administrations (days 0, 7, 14), the lower left second molar was extracted (day 42). Further ZA administration (day 49) and euthanasia (day 70) were conducted. After confirmation of ZA-induced jaw necrosis (histologic and microtomographic analysis), spectroscopic and mechanical parameters were assessed. RESULTS: ZA-treated groups presented lower bone density due to impaired healing of tooth extraction socket. Sex-related alterations were also observed, with lower bone density in females. Regarding biomechanical parameters, sex and treatment exerted independent influences. ZA, although decreasing flexural modulus and yield stress, increases stiffness mainly due to a higher bone volume. Females show less resistance to higher loads compared to males (considering dimension-independent parameters). Additionally, ZA increases crystallinity in bone and dental structure (p < 0.05). In summary, although strongly related to osteonecrosis occurrence, ZA modifies bone and dental mineral matrix, improving bone mechanical properties. CONCLUSION: Despite sex-dependent differences in bone biomechanics and density, osteonecrosis was established with no sex influence. No synergistic association between sex and treatment factors was observed in this study.

Susceptibility of fluorotic enamel to dental erosion-abrasion.

Dental hard tissue conditions can be of pre- or post-eruptive nature, such as enamel fluorosis and erosive tooth wear (ETW), respectively. Dental enamel fluorosis is caused by the chronic and excessive intake of fluoride during enamel development, leading to increased fluoride concentration and increased porosity. ETW has become a common clinical condition and often impairs dental function and aesthetics. This in vitro study tested the hypothesis that fluorotic enamel presents different susceptibility to dental erosion-abrasion. It consisted of a 3×3×2 factorial design, considering a) fluorosis severity: sound (TF0), mild (TF1-2), moderate (TF3-4); b) abrasive challenge: low, medium, and high; and c) erosive challenge: yes or no. A total of 144 human teeth were selected according to the three fluorosis severity levels (n=48), and subdivided into six groups (n = 8) generated by the association of the different erosive and abrasive challenges. Enamel blocks (4×4 mm) were prepared from each tooth and their natural enamel surfaces subjected to an erosion-abrasion cycling model. After cycling, the depth of the lesions in enamel was assessed by profilometry. ANOVA showed that the three-way and two-way interactions among the factors were not significant (p > 0.20). Enamel fluorosis level (p=0.638) and abrasion level (p = 0.390) had no significant effect on lesion depth. Acid exposure caused significantly more enamel surface loss than water (p < 0.001). Considering the limitations of this in vitro study, fluorosis did not affect the susceptibility of enamel to dental erosion-abrasion.

Influence of carbonated acid beverage on fracture resistance and marginal gap formation in different restorative approaches to non-carious cervical lesions.

OBJECTIVE: This study is to evaluate fracture resistance, failure mode, and gap formation at the restorative interface of unrestored or restored non-carious cervical lesions (NCCLs) submitted to a short-term erosive environment. MATERIALS AND METHODS: Artificial NCCLs were produced in vitro in bovine incisors, and were randomly divided into four restorative resins groups (n = 22): nanohybrid-NR; bulk-fill-BR; flow with a nanohybrid layer-FNR; bulk-fill with a nanohybrid layer-BNR; and a group unrestored-UR (n = 16). Half of the specimens were submitted to an erosive challenge (per 5 min, 3 × a day for 7 days, before and after restoration), and the other half, was immersed in artificial saliva. After, all teeth undergone thermal (5 ºC, 37 ºC, and 55 ºC, 3600 cycles) and mechanical (50 N, 2 Hz, 300,000 cycles) aging. Eighty teeth were subjected to compressive loading, and resistance and failures were analyzed, while 24 teeth were evaluated for gaps by microcomputed tomography. Statistical tests were performed (p < 0.05). RESULTS: The restorative approaches affected fracture resistance (η2p = 0.14, p = 0.023), and gap formation (η2 = 0.18, p = 0.012) and so did the immersion medium (fracture η2p = 0.09, p = 0.008; gap η2 = 0.09, p = 0.017). BNR showed the highest resistance, while UR the lowest. FNR showed the highest gaps in both immersion media. Neither the resin groups nor the immersion media were associated with failure mode. CONCLUSIONS: The erosive immersion medium based in acid beverages has been shown to affect NCCLs with or without restoration, but when Bulk-Fill resin is covered by nanohybrid resin, the performance is good. CLINICAL RELEVANCE: Erosion negatively affects restorations, but unrestored NCCL shows worse biomechanical performance in stress-bearing situations.

Organic volume and permeability variations in the surface layer of artificial and natural enamel carious lesions.

OBJECTIVES: Test the hypothesis the type of enamel caries (natural, artificial induced by gel, and artificial induced by acid solutions) affect the organic volume and the permeability of the surface layer in enamel caries lesions. DESIGN: Artificial enamel caries, induced by either acidic solution (organic-poor; Group 1) or acidic gel (organic-rich; Group 2), and natural non-cavitated inactive approximal enamel caries lesions (NEC; Group 3) were obtained, from which longitudinal ground sections were prepared. Measurements of the mineral (Vmin) (by microradiography), and water (α) and organic (ß) volumes (by optical birefringence) were obtained at three points in the surface layer (n = 30/group). RESULTS: The main outcomes were the ratio between experimental ß by predicted ß (ß Ratio) and the ratio between experimental and predicted permeabilities (αd Ratio). ß Ratio in Group 1 was lower than in Groups 2 (Cohen's d: -1.81; 95% CI:-1.45,-2.32; p < 0.001) and 3 (Cohen's d: -0.71; 95% CI:-0.27,-1.18; p = 0.004), and Group 2 surpassed Group 3 (Cohen's d: 0.49; 95% CI:0.07,0.94; p = 0.03). αd Ratio in Group 1 was higher than in Groups 2 (Cohen's d: 1.86; 95% CI:1.49,2.33; p < 0.001) and 3 (Cohen's d: 0.60; 95% CI:0.18,1.14; p = 0.01), and Group 3 surpassed Group 2 (Cohen's d: 0.61; 95% CI:0.23,1.07; p = 0.01). CONCLUSIONS: The highest organic volume and the lowest permeability occurred at the surface layer of gel-induced artificial enamel caries lesions, which should be preferred in in vitro studies on de- and remineralization and resin infiltration.

Improved mineralization of dental enamel by electrokinetic delivery of F- and Ca2+ ions.

This in vitro study evaluated the effects of the infiltration of F- and Ca2+ ions into human enamel by electrokinetic flow (EKF) on the enamel microhardness and F- content. Sound human enamel ground sections of unerupted third molars were infiltrated with de-ionized water by EKF and with F- ion by EKF respectively. All samples were submitted to two successive transverse acid-etch biopsies (etching times of 30 s and 20 min) to quantify F- ion infiltrated deep into enamel. Remarkably, sound enamel showed a large increase in microhardness (MH) after infiltration of NaF (p < 0.00001) and CaCl2 (p = 0.013) by EKF. Additionally, NaF-EKF increased the remineralization in the lesion body of artificial enamel caries lesions compared to controls (p < 0.01). With the enamel biopsy technique, at both etching times, more F- ions were found in the EKF-treated group than the control group (p << 0.05), and more fluoride was extracted from deeper biopsies in the NaF-EKF group. In conclusion, our results show that EKF treatment is superior in transporting Ca2+ and F- ions into sound enamel when compared to molecular diffusion, enhancing both the mineralization of sound enamel and the remineralization of artificial enamel caries.

New Theory Illustrates the Formation of Enamel CUP-Shaped Lesions on Occlusal Surfaces.

We propose a new theory for enamel cupping lesions formation. At early stages, naturally formed cupping lesions showed increased porosity at two structural prismatic traits: the central cone extending into the enamel-dentine junction and the type-I Hunther-Schreger bands (HSB), suggesting them to be the main drivers for cupping lesion formation and development. In addition, these lesions were circumscribed by type-II HSBs, which present lower surface porosity and higher resistance to wear. This theory was verified in in vitro observations, where both the central cone and the type-I HSB of cuspal enamel showed higher susceptibility to wear, potentially elucidating the mechanisms involved on cupping lesion formation.

Fluorotic Enamel Susceptibility to Dental Erosion and Fluoride Treatment

Abstract The purpose of this in vitro study was to test the hypothesis that fluoride treatment can prevent dental erosion on fluorotic enamel of different severities. It followed a 3×2 factorial design, considering a) fluorosis severity: sound (TF0, Thylstrup-Fejerskov Index), mild (TF1-2), moderate (TF3-4); and b) fluoride treatment: 0 (negative control) and 1150ppmF. Human molars with the three fluorosis severities (n=16, each) were selected and randomly assigned to the two fluoride treatments (n=8). Enamel blocks (4×4mm) were prepared from each tooth and subjected to a dental erosion cycling model, for 10 days. The daily cycling protocol consisted of erosive challenges (1% citric acid, pH 2.4), interspersed by periods of immersion in artificial saliva, and three 2-minute treatments with either 0 or 1150ppm F. The enamel volume loss (mm3) was calculated by subtracting values obtained by microtomography before and after cycling. Two-Way ANOVA showed no significant interaction between fluorosis severity and fluoride treatment (p=0.691), and no significant effect for either fluorosis severity (TF0 mean±standard-deviation: 13.5(10-2±0.42(10-2, TF1-2: 1.50(10-2±0.52(10-2, TF3-4: 1.24(10-2±0.52(10-2, p=0.416) or treatment (0ppmF: 1.49(10-2±0.53(10-2; 1150ppmF: 1.21(10-2±0.42(10-2; p=0.093), when evaluated independently. Considering the limitations of this in vitro study, the presence and severity of fluorosis in enamel do not appear to affect its susceptibility to dental erosion. Fluoride treatment was not effective in preventing the development of dental erosion in both sound and fluorotic enamel substrates under our experimental conditions.

Resumo Este estudo in vitro foi testou a hipótese de que o tratamento com flúor pode prevenir a erosão dentária no esmalte fluorótico de diferentes severidades. O objetivo deste estudo foi: investigar o efeito protetor dos fluoretos contra a erosão e abrasão simuladas no esmalte fluorótico. Seguiu um desenho fatorial 3×2, considerando a) severidade da fluorose em 3 níveis: hígido (TF0, Índice Thylstrup-Fejerskov), suave (TF1-2), moderada (TF3-4); b) tratamento com flúor: 0 (controle negativo) e 1150ppmF. Molares humanos com as três severidades de fluorose (n=16, cada) foram selecionados e distribuídos aleatoriamente para os dois tratamentos com flúor (n=8). Blocos de esmalte (4×4mm) foram preparados a partir de cada dente e submetidos a um modelo de ciclo de erosão dentária, por 10 dias. O protocolo de ciclagem diária consistiu em seis desafios erosivos de 5 minutos (1% de ácido cítrico, pH 2,4), intercalados por seis períodos de imersão em saliva artificial e três tratamentos de 2 minutos com 0 ou 1150ppmF. O volume do esmalte perdido foi calculado subtraindo o perfil superficial 3D obtido por microtomografia antes e depois da ciclagem. A ANOVA de dois fatores não mostrou interação significativa entre a severidade da fluorose e o tratamento com flúor (p = 0,691) e nenhum efeito significativo para a severidade da fluorose (TF0 média+/desvio padrão: 13,5(10-2±0,42(10-2, TF1-2: 1,50(10-2±0,52(10-2, TF3-4: 1,24(10-2±0,52(10-2, p=0,416) ou tratamento (0: 1,49(10-2±0,53(10-2; 1150ppmF: 1,21(10-2±0,42(10-2, p=0,093), quando avaliados independentemente. Considerando as limitações deste estudo in vitro, a presença e severidade da fluorose no esmalte não parece afetar sua suscetibilidade à erosão dentária. O tratamento com flúor não foi eficaz na prevenção do desenvolvimento da erosão dentária em esmalte hígido e fluorótico, sob as condições experimentais utilizadas.

Influence of different working lengths on the shaping ability of Reciproc Blue in the apical third and apical foramen: a micro-computed tomographic study

Aim: This study aimed to assess the shaping ability of Reciproc Blue in the apical third and apical foramen of moderately curved canals at different working lengths (WLs), by micro-computed tomography. Methods: Thirty-six mesial roots (mesiobuccal and mesiolingual canals) were included, each with 2 separate root canals and independent apical foramina, according to type IV of Vertucci's classification of first and second mandibular molars. The canals were instrumented at three different WLs: G-1, 1mm short of the major apical foramen; G0, at the major apical foramen; G+1, 1mm beyond the major apical foramen. The groups were assessed for changes in root canal volume and untouched wall area in the apical third. Groups G0 and G+1 were also compared for percentage of untouched walls at the apical foramen. One-way ANOVA (post hoc Tukey test) and Student's t-test adopted a 5% level of significance. Results: Root canal volumes (mm3) in the apical third were 22.86±10.46, 44.48±24.91, and 55.71±21.32 in G-1, G0 and G+1, respectively. G-1 volume following instrumentation increased significantly less than that of G0 or G+1 (P>.05); G0 did not differ from G+1. The percentage of untouched wall area in the apical third did not differ among the three groups (P>.05). G0 and G+1 did not differ regarding untouched walls in the major apical foramem walls. Conclusion: Extending the WL from 1mm short of the apical foramen to a point at and beyond the WL increases the apical third volume without increasing the prepared area. Untouched surface areas of the apical foramen were not modified by instrumentation at or beyond the foramen

Susceptibility of fluorotic enamel to dental erosion-abrasion

Abstract Dental hard tissue conditions can be of pre- or post-eruptive nature, such as enamel fluorosis and erosive tooth wear (ETW), respectively. Dental enamel fluorosis is caused by the chronic and excessive intake of fluoride during enamel development, leading to increased fluoride concentration and increased porosity. ETW has become a common clinical condition and often impairs dental function and aesthetics. This in vitro study tested the hypothesis that fluorotic enamel presents different susceptibility to dental erosion-abrasion. It consisted of a 3×3×2 factorial design, considering a) fluorosis severity: sound (TF0), mild (TF1-2), moderate (TF3-4); b) abrasive challenge: low, medium, and high; and c) erosive challenge: yes or no. A total of 144 human teeth were selected according to the three fluorosis severity levels (n=48), and subdivided into six groups (n = 8) generated by the association of the different erosive and abrasive challenges. Enamel blocks (4×4 mm) were prepared from each tooth and their natural enamel surfaces subjected to an erosion-abrasion cycling model. After cycling, the depth of the lesions in enamel was assessed by profilometry. ANOVA showed that the three-way and two-way interactions among the factors were not significant (p > 0.20). Enamel fluorosis level (p=0.638) and abrasion level (p = 0.390) had no significant effect on lesion depth. Acid exposure caused significantly more enamel surface loss than water (p < 0.001). Considering the limitations of this in vitro study, fluorosis did not affect the susceptibility of enamel to dental erosion-abrasion.

Structure and Chemical Composition of ca. 10-Million-Year-Old (Late Miocene of Western Amazon) and Present-Day Teeth of Related Species.

Molecular information has been gathered from fossilized dental enamel, the best-preserved tissue of vertebrates. However, the association of morphological features with the possible mineral and organic information of this tissue is still poorly understood in the context of the emerging area of paleoproteomics. This study aims to compare the morphological features and chemical composition of dental enamel of extinct and extant terrestrial vertebrates of Crocodylia: Purussaurus sp. (extinct) and Melanosuchus niger (extant), and Rodentia: Neoepiblema sp. (extinct) and Hydrochoerus hydrochaeris (extant). To obtain structural and chemical data, superficial and internal enamel were analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (SEM-EDS). Organic, mineral, and water content were obtained using polarizing microscopy and microradiography on ground sections of four teeth, resulting in a higher organic volume than previously expected (up to 49%). It is observed that both modern and fossil tooth enamel exhibit the same major constituents: 36.7% Ca, 17.2% P, and 41% O, characteristic of hydroxyapatite. Additionally, 27 other elements were measured from superficial enamel by inductively coupled mass spectrometry (ICP-MS). Zinc was the most abundant microelement detected, followed by Pb, Fe, Mg, and Al. Morphological features observed include enamel rods in the rodent teeth, while incremental lines and semiprismatic enamel were observed in the alligator species. The fossil enamel was in an excellent state for microscopic analyses. Results show that all major dental enamel's physical, chemical, and morphological features are present both in extant and extinct fossil tooth enamel (>8.5 Ma) in both taxa.

Orofacial antinociceptive effects of perillyl alcohol associated with codeine and its possible modes of action.

This study evaluated the orofacial antinociceptive effect of (S)-(-)-perillyl alcohol (PA) associated with codeine (C) and investigated the possible molecular anchorage mechanisms of PA. Mice (n = 5 per group) were treated with PA alone and associated with codeine and assigned to the following groups: 75.0 mg/kg PA; 75.0 mg/kg PA + C 30 mg/kg; PA 37.5 mg/kg + C 15.0 mg/kg; C 30.0 mg/kg; and control. Nociception was induced by formalin, capsaicin, and glutamate, and was quantified based on the duration (in seconds) of face grooming. The possible mechanisms of action were evaluated by molecular docking study. In the formalin test, PA75/C30 presented an effect in the neurogenic (p < 0.0001) and inflammatory (p < 0.005) phases. Mice treated with PA75 (p < 0.0001) and PA75/C30 (p < 0.0005) showed a reduced nociceptive behavior in the capsaicin test. Glutamate-induced nociception also was blocked by PA75 (p < 0.0005) and C30 (p < 0.0005). The molecular anchorage analysis indicated high negative binding energy values for the evaluated receptors, especially glutamate receptors (AMPA -79.57 Kcal/mol, mGLUR6 -71.25, and NMDA -66.33 Kcal/mol). PA associated with codeine showed orofacial antinociceptive activity, with theoretical evidence of interaction with glutamate receptors.

Comparison of Self-Etching Adhesives and Etch-and-Rinse Adhesives on the Failure Rate of Posterior Composite Resin Restorations: A Systematic Review and Meta-Analysis.

The aim of this study was to perform a systematic review with meta-analysis on the comparison of self-etching adhesives and etch-and-rinse adhesives with respect to the failure rate of posterior composite resin restorations. The study protocol was registered in PROSPERO (CRD42017078015), following PRISMA recommendations and PICO search strategy. Literature search was performed in the following databases: MEDLINE, ISI Web of Science, LILACS, SCOPUS, and Cochrane Library through July 2021. Six studies from five randomized clinical trials were included in the qualitative synthesis. The funnel plot detected important bias (all studies out of the funnel area). The meta-analysis showed a positive summary Cohen H effect size of 0.406 (95% CI: 0.100; 0.713, p = 0.009), favoring etch-and-rinse adhesives. The total number of failures (including restorations that required replacement and those that did not require replacement) were attributed to either marginal adaptation (five studies) or marginal staining (one study). A very low certainty of the evidence was obtained through GRADE analysis. In conclusion, current available evidence indicates that etch-and rinse adhesives performed better (with a low effect size) than self-etching adhesives in terms of failure rates in posterior composite restorations.

Orofacial antinociceptive effects of perillyl alcohol associated with codeine and its possible modes of action

Abstract This study evaluated the orofacial antinociceptive effect of (S)-(-)-perillyl alcohol (PA) associated with codeine (C) and investigated the possible molecular anchorage mechanisms of PA. Mice (n = 5 per group) were treated with PA alone and associated with codeine and assigned to the following groups: 75.0 mg/kg PA; 75.0 mg/kg PA + C 30 mg/kg; PA 37.5 mg/kg + C 15.0 mg/kg; C 30.0 mg/kg; and control. Nociception was induced by formalin, capsaicin, and glutamate, and was quantified based on the duration (in seconds) of face grooming. The possible mechanisms of action were evaluated by molecular docking study. In the formalin test, PA75/C30 presented an effect in the neurogenic (p < 0.0001) and inflammatory (p < 0.005) phases. Mice treated with PA75 (p < 0.0001) and PA75/C30 (p < 0.0005) showed a reduced nociceptive behavior in the capsaicin test. Glutamate-induced nociception also was blocked by PA75 (p < 0.0005) and C30 (p < 0.0005). The molecular anchorage analysis indicated high negative binding energy values for the evaluated receptors, especially glutamate receptors (AMPA -79.57 Kcal/mol, mGLUR6 -71.25, and NMDA -66.33 Kcal/mol). PA associated with codeine showed orofacial antinociceptive activity, with theoretical evidence of interaction with glutamate receptors.

O ensino odontológico e os desafios relacionados ao cumprimento dos novos protocolos de biossegu-rança no contexto da pandemia da COVID-19 / Dental education and the challenges related to complying with the new biosafety protocols in the COVID-19 pandemic context

O objetivo deste estudo foi apresentar os desafios relacionados ao cumprimento dos novos protocolos de biossegurança, na perspectiva do retorno das atividades presenciais nas instituições de ensino superior em Odontologia,no cenário da pandemia da COVID-19.Tratou-se de um estudo qualitativo, de caráter exploratório, ancorado na técnica de pesquisa documental. Foram analisados os documentos publicados pelo Ministério da Educação (MEC), Conselho Federal de Odontologia (CFO) e Associação Brasileira de EnsinoOdontológico (ABENO).Os documentos foram coletados nos websitesdas entidades selecionadas. O tratamento dos dados qualitativos foi realizado por meio da análise de conteúdo temática, sendo comparadas qualitativamente as diferentes publicações, identificando-se pontos convergentes, divergentes ou ausentes entre os documentos.Combase na problematização do objeto em questão, foram emitidas sugestões a partir das fragilidades e potencialidades relacionadas à execução das recomendações. Os dados foram distribuídos nas unidades de análise "sala de espera", "clínica" e "laboratório". As principais potencialidades foram relacionadas à diminuição do risco biológico de transmissão de patógenos e à adequação de espaços físicos em ambientes mais ergonômicos de aprendizagem. Quanto às fragilidades, aponta-se o aumento de custos para discentes e instituições e a redução no número de atendimentos. Existem desafios a serem considerados em relação ao cumprimento dos novos protocolos de biossegurança no retorno das atividades práticas nos cursos deOdontologia durante a pandemia da COVID-19 (AU).

This study presents challenges related to the fulfillment of the new biosafety protocols aiming to return the face-to-face activities in higher education institutions in Dentistry considering the pandemic scenario of COVID-19. It was a qualitative, exploratory study, anchored in the technique of documentary research. We analyzed documents published by the Ministry of Education(MEC), the Federal Council of Dentistry (FCD) and the Brazilian Association for Dental Education (BADE). The documents were collected on websites of the selected entities. The treatment of qualitative data obtained was carried out by thematic content analysisto compare qualitatively the different documents by identifying convergent, divergent or absent points between them. From the problematization of the object under study, suggestions were made based on the weaknesses and potentialities related to the execution of the recommendations. Data were distributed in the analysis units "waiting room", "clinic" and "laboratory". The main potentialities were related to the reduction of the biological risk of transmission of pathogens and the adaptation of physicalspaces in more ergonomic learning environments. As for the weaknesses, there are increased costs for students and institutions and reduced number of visits. There are challenges to be considered to comply with the new biosafety protocols in the return of practical activities in Dentistry Courses during the COVID-19 pandemic (AU).

Development of castor polyurethane scaffold (Ricinus communisL.) and its effect with stem cells for bone repair in an osteoporosis model.

The development of 'smart' scaffolds has achieved notoriety among current prospects for bone repair, especially for chronic osteopathy, such as osteoporosis. Millions of individuals in the world suffer from poor bone healing due to osteoporosis. The objective of this work was to produce and characterize castor polyurethane (PU) scaffolds (Ricinus communisL.)andevaluate itsin vitrobiocompatibility with stem cells and osteoinductive effectin vivoon bone failures in a leporid model of osteoporosis. The material was characterized using Fourier-transform infrared spectroscopy, thermogravimetric analysis, SEM, and porosity analysis. Then, the biocompatibility was assessed by adhesion using SEM and cytotoxicity in a 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium assay. The osteoinductive effectin vivowas determined in bone defects in rabbit tibias (Oryctolagus cuniculus) submitted to castor PU scaffold, castor PU scaffold associated with stem cells, and negative control, after four and eight weeks, evaluated by computed microtomography and histopathology. The scaffolds were porous, with an average pore size of 209.5 ± 98.2 µm, absence of cytotoxicity, and positive cell adhesivenessin vitro.All the animals presented osteoporosis, characterized by multifocal osteoblastic inactivity and areas of mild fibrosis. There were no statistical differences between these treatments in the fourth week of treatment. In the eighth week, the treatment with castor PU scaffold alone induced more significant bone formation when compared to the other groups, followed by treatment with an association between castor PU scaffold and stem cells. The castor PU scaffold was harmless to cell culture, favoring cell adhesiveness and proliferation, in addition to inducing bone neoformation in osteoporotic rabbits.

Shaping efficiency of XP-endo shaper and Mtwo instruments in long oval root canals: A micro-CT study.

This study evaluated the shaping ability of XP-endo Shaper and Mtwo systems in long-oval-shaped canals of extracted human mandibular molars using micro-computed tomography (micro-CT). Images recorded before and after preparation were evaluated for morphometric measures regarding increase in canal volume, dentin removed, surface area, untouched walls and structure model index (SMI). Data were statistically analysed using the Mann-Whitney test with 5% of significance. On both groups, the root canal preparation significantly increased all analysed parameters (P > 0.05). There was no statistical difference between XP-endo Shaper and Mtwo systems in the increase of the canal volume (30.50%-27.82%), in volume of dentin removed (2.77%-2.40%), in the increase of the canal surface area (11.30%-8.86%), in canal untouched surfaces (9.57%-8.51%) and in the SMI (2.59%-2.68%), respectively. XP-endo Shaper and Mtwo systems showed similar shaping efficiency and were not able to completely prepare the walls of long-oval-shaped canals of extracted human mandibular molars.

The effect of high concentration of zoledronic acid on tooth induced movement and its repercussion on root, periodontal ligament and alveolar bone tissues in rats.

Zoledronic acid (ZA) is often prescribed for osteoporosis or resorptive metabolic bone disease. This study aims to evaluate the effect of ZA on orthodontic tooth movement (OTM) and root and bone resorption and its repercussion on root, periodontal ligament and alveolar bone tissues. The experimental group consisted of 72 Wistar rats divided in four subgroups: Naive, Saline and Zoledronic Acid groups at the concentration of 0.2 mg/kg [ZA (0.2)] or 1.0 mg/kg [ZA (1.0)]. The animals were subjected to i.v (dorsal penile vein) administrations of ZA or saline solution, on days 0, 7, 14 and 42. Under anesthesia, NiTi springs were installed in the first left maxillary molar with 50gf allowing the OTM, except for the negative control group (N) for mesial movement of the left first maxillary teeth. The animals were sacrificed and maxillae were removed for macroscopic and histopathological analyzes, scanning electron microscopy, computerized microtomography and confocal microscopy. Treatment with ZA decreased the OTM and the number of osteoclasts and loss of alveolar bone when compared to the naive and saline groups. Reduction of radicular resorption, increased necrotic areas and reduced vascularization in the periodontal ligament were observed in the ZA groups. ZA interferes with OTM and presents anti-resorptive effects on bone and dental tissues associated with a decreased vascularization, without osteonecrosis.