Role of non-carious cervical lesions multicausality in the behavior of respective restorations.

OBJECTIVES: To evaluate biocorrosion and eccentric occlusal loading interplay in marginal quality of cervical restorations. METHODS: Cervical wedge-shaped cavities were prepared in extracted premolars and restored with a composite. Premolars underwent either an erosive challenge (E: 1% citric acid/10 min), eccentric occlusal loading (EOL: 150 N/2.5 Hz/106 cycles), E before EOL (E + EOL), E intermediate to EOL (EOL/E/EOL), E after EOL (EOL + E), or no E or EOL (C: control). Marginal quality was analyzed based on a series of Optical Coherence Tomography images. Each of the margins was assigned a gap score (0, 1, 2, or 3) and measurement (µm). For each margin, scores data were analyzed with Kruskall Wallis and Dunn tests, and µm data, with Kruskall Wallis. Overall and for each group, the different margins were compared using Wilcoxon signed-rank test, and the correlation between scores and µm, Spearman's correlation coefficient (α = 0.05). RESULTS: E and EOL, even if associated, did not influence enamel marginal quality. EOL/E/EOL impaired dentin/cementum marginal quality only in the case of scores and compared to E. E + EOL, EOL + E or EOL and even C, without differences between each other, did not influence results differently from E or EOL/E/EOL. Margins in dentin/cementum always showed lengthier gaps. Except for C, E and EOL + E cervical margin, there was a strong positive correlation between scores and µm. CONCLUSIONS: Eccentric occlusal loading and/or biocorrosion cannot be assumed as causes of marginal failure of cervical restorations in wedge-shaped cavities. A relevant concern may still be the establishment of adhesive interfaces in dentin/cementum. CLINICAL SIGNIFICANCE: Although non-carious cervical lesions are strongly being recognized multifactorial and their respective restorations not always behave as expected, biocorrosion and eccentric occlusal loading interplay cannot serve as an explanation for marginal gaps they often present.

Oral alterations in patients with cystinosis.

Cystinosis is a rare autosomal recessive lysosomal storage disorder, which leads to abnormal accumulation of cysteine in various organs, including progressive dysfunction of kidneys. The most severe and frequent form, affecting ∼95% of patients, is termed infantile nephropathic cystinosis (NC) (OMIM 219800). We have reported oral findings in two patients with NC and described esthetic and functional rehabilitation in one of them. The first case describes a 16-year-old male patient, who was diagnosed with NC when he was 1-year-old. The patient exhibited generalized enamel hypoplasia, grade 1 drug-induced gingival overgrowth, caries lesion in molar tooth and supernumerary tooth (ie, distomolar). The second case describes a 14-year-old male patient diagnosed with NC at 3 years old. Clinical examination revealed generalized enamel hypoplasia and grade 1 drug-induced gingival overgrowth. Radiographic examination showed supernumerary tooth (mesiodens). The treatment included gingivoplasty and restoration with direct composite resin. The severity of hypoplasia highlights the importance of a dental rehabilitation treatment, as proposed here. Direct restoration with composite resin allowed harmony, function, and esthetics to be restored, in addition to being a rapid and low-cost technique.

Preservation in Young Patients of Pulp Vitality and Anatomical-Functional Restoration of the Lost Structure.

Often, young patients (≤30 years old) present with carious lesions that progress acutely, compromising a large amount of tooth structure. In these cases, a treatment to prevent the occurrence of pulp exposure and promote remineralization of caries-affected dentin is necessary to maintain healthy dental structure and allow more conservative interventions. The approach will be different when pulp exposure occurs: The therapeutic treatments will be focused on reparative dentin formation and prevention of microorganisms penetrating the pulp organ. Due to the different possible treatments that can be performed to avoid pulp necrosis and the various materials that can be used for this purpose, professionals may have some difficulties understanding all the indications for conservative pulp treatments. The objective of this article is to describe and discuss a successful pulp capping and stepwise excavation associated with restorative treatment for deep caries lesions of anterior upper teeth.

Surface roughness and wear of resin cements after toothbrush abrasion.

Increased surface roughness and wear of resin cements may cause failure of indirect restorations. The aim of this study was to evaluate quantitatively the surface roughness change and the vertical wear of four resin cements subjected to mechanical toothbrushing abrasion. Ten rectangular specimens (15 × 5 × 4 mm) were fabricated according to manufacturer instructions for each group (n = 10): Nexus 3, Kerr (NX3); RelyX ARC, 3M ESPE (ARC); RelyX U100, 3M ESPE (U100); and Variolink II, Ivoclar/Vivadent (VL2). Initial roughness (Ra, µm) was obtained through 5 readings with a roughness meter. Specimens were then subjected to toothbrushing abrasion (100,000 cycles), and further evaluation was conducted for final roughness. Vertical wear (µm) was quantified by 3 readings of the real profile between control and brushed surfaces. Data were subjected to analysis of variance, followed by Tukey's test (p < 0.05). The Pearson correlation test was performed between the surface roughness change and wear (p < 0.05). The mean values of initial/final roughness (Ra, µm)/wear (µm) were as follows: NX3 (0.078/0.127/23.175); ARC (0.086/0.246/20.263); U100 (0.296/0.589/16.952); and VL2 (0.313/0.512/22.876). Toothbrushing abrasion increased surface roughness and wear of all resin cements tested, although no correlation was found between those variables. Vertical wear was similar among groups; however, it was considered high and may lead to gap formation in indirect restorations.

Surface roughness and wear of resin cements after toothbrush abrasion

Increased surface roughness and wear of resin cements may cause failure of indirect restorations. The aim of this study was to evaluate quantitatively the surface roughness change and the vertical wear of four resin cements subjected to mechanical toothbrushing abrasion. Ten rectangular specimens (15 × 5 × 4 mm) were fabricated according to manufacturer instructions for each group (n = 10): Nexus 3, Kerr (NX3); RelyX ARC, 3M ESPE (ARC); RelyX U100, 3M ESPE (U100); and Variolink II, Ivoclar/Vivadent (VL2). Initial roughness (Ra, µm) was obtained through 5 readings with a roughness meter. Specimens were then subjected to toothbrushing abrasion (100,000 cycles), and further evaluation was conducted for final roughness. Vertical wear (µm) was quantified by 3 readings of the real profile between control and brushed surfaces. Data were subjected to analysis of variance, followed by Tukey’s test (p < 0.05). The Pearson correlation test was performed between the surface roughness change and wear (p < 0.05). The mean values of initial/final roughness (Ra, µm)/wear (µm) were as follows: NX3 (0.078/0.127/23.175); ARC (0.086/0.246/20.263); U100 (0.296/0.589/16.952); and VL2 (0.313/0.512/22.876). Toothbrushing abrasion increased surface roughness and wear of all resin cements tested, although no correlation was found between those variables. Vertical wear was similar among groups; however, it was considered high and may lead to gap formation in indirect restorations.

Influence of volume and activation mode on polymerization shrinkage forces of resin cements.

The concern with the polymerization shrinkage of restorative resin composites also applies to resin cements. The aim of this study was to evaluate the influence of volume and polymerization mode on forces generated during polymerization shrinkage (FGPS) of resin cements. Two light-cured resin cements--Variolink II (VL; Ivoclar Vivadent) and Nexus 3 (NX; Kerr)--and two self-cured resin cements - Multilink (ML; Ivoclar Vivadent) and Cement Post (CP; Angelus) - were inserted between two rectangular steel bases (6x2 mm) with distance set at 0.1, 0.3 and 0.5 mm, establishing a variation of volume. These steel bases were attached to a universal test machine with 50 kg load cell and forces (N) were registered for 10 min. Values of maximum forces generated by each material were subjected to two-way ANOVA and Tukey's test for individual comparisons (α=0.05). VL, NX and CP developed increasing FGPS as the volume of material increased, while ML presented the opposite behavior. It may be concluded that higher volume increases FGPS even with a concomitant decrease of C-factor, unless the resin cements present lower force generation rates as a function of time in combination with a low C-factor, resulting in stress relief and consequently lower values of FGPS.

Influence of Volume and Activation Mode on Polymerization Shrinkage Forces of Resin Cements

The concern with the polymerization shrinkage of restorative resin composites also applies to resin cements. The aim of this study was to evaluate the influence of volume and polymerization mode on forces generated during polymerization shrinkage (FGPS) of resin cements. Two light-cured resin cements - Variolink II (VL; Ivoclar Vivadent) and Nexus 3 (NX; Kerr) - and two self-cured resin cements - Multilink (ML; Ivoclar Vivadent) and Cement Post (CP; Angelus) - were inserted between two rectangular steel bases (6x2 mm) with distance set at 0.1, 0.3 and 0.5 mm, establishing a variation of volume. These steel bases were attached to a universal test machine with 50 kg load cell and forces (N) were registered for 10 min. Values of maximum forces generated by each material were subjected to two-way ANOVA and Tukey's test for individual comparisons (α=0.05). VL, NX and CP developed increasing FGPS as the volume of material increased, while ML presented the opposite behavior. It may be concluded that higher volume increases FGPS even with a concomitant decrease of C-factor, unless the resin cements present lower force generation rates as a function of time in combination with a low C-factor, resulting in stress relief and consequently lower values of FGPS.

Preocupação com a contração de polimerização de resinas compostas restauradoras também tem sido associada aos cimentos resinosos. O objetivo deste artigo foi avaliar a influência do volume e do modo de polimerização sobre as forças geradas durante a contração de polimerização (FGPS) de cimentos resinosos. Dois cimentos de ativação dual: Variolink II (VL - Ivoclar Vivadent) e Nexus 3 (NX - Kerr) e dois de ativação química: Multilink (ML - Ivoclar Vivadent) e Cement Post (CP - Angelus) foram inseridos entre as duas bases de aço retangulares (6x2 mm) com a distância ajustada em 0,1, 0,3 e 0,5 mm, estabelecendo uma variação no volume. Estas bases de aço foram fixadas a uma máquina de teste universal (Emic DL 500, com célula de carga de 50 kg) e as forças (N) foram registradas por 10 min. Os valores máximos de tensões geradas por cada material foram submetidas à ANOVA a dois critérios, seguido do teste de Tukey (p<0,05) para comparações individuais. VL, NX e CP desenvolveram maiores FGPS quando o volume de material aumentou, enquanto ML apresentou o comportamento inverso. Maiores volumes aumentam as FGPS mesmo com redução concomitante do Fator-C, a menos que o cimento resinoso apresente uma baixa taxa de geração de força em função do tempo associado a um baixo Fator-C, o que resulta em alívio das tensões e consequentemente menores valores de FGPS.

Capacidade de vedamento de diferentes materiais usados como barreira protetora cervical no clareamento interno colocado em duas alturas com respeito a junção amelocementaria / In vitro sealing capacity of different materials used as protective cervical barrier in internal bleaching placed in two heights respect to the cementoenamel junction

O objetivo deste trabalho foi avaliar a efetividade do vedamento apical e linear de diferentes materiais utilizados como barreira protetora cervical (BPC) no clareamento interno, localizados ao mesmo nível e 1mm acima da junção amelocementária (JAC). Cento doze dentes bovinos foram divididos em sete grupos de acordo com o material de BPC utilizado, além de um grupo controle, e em dois subgrupos de acordo com a localização, sendo assim distribuídos: grupo GRC com resina composta sem sistema adesivo (Z250); grupo GVR com Cimento de Ionômero de Vidro (CIV) convencional (Vidrion R); grupo GVB com CIV modificado por resina de forramento (Vitrebond); grupo GVTR com CIV modificado por resina restaurador (Vitremer); grupo GCZ com Cimento de Fosfato de Zinco (CIMENTO DE ZINCO); grupo GCT com material restaurador provisório (Coltosol); grupo GCF com material provisório fotopolimerizável (Clip F); e grupo controle com Gutapercha e cimento selador (Fillapex). Os dentes foram clareados pela técnica walking bleach durante sete dias e após esse período foram corados durante 48hrs, enquanto armazenados com temperatura de 37oC e umidade a 100%. Foi realizada avaliação através de inspeção visual. A análise estatística foi feita através da análise de variância a dois critérios (ANOVA-2) e teste de Tukey. Os grupos experimentais revelaram que o único fator que representou importância no vedamento apical (F=26,42; p=0,00) e linear (F=29,73; p=0,00) foi o tipo de material empregado, independente da sua localização. Os grupos GRC e GCZ apresentaram os piores valores de vedamento e apresentaram diferença estatisticamente significativa (p=<0,05) quando comparados com os outros grupos e com o grupo controle. Os melhores resultados foram encontrados nos grupos GCT, GCF, GVB, GVTR e GVR, porém sem diferença estatisticamente significativa entre eles (p=<0,05) e com o grupo controle. Através do teste de correlação de Spearman verificou-se correlação positiva (r=0,911...

The aim of this study was to evaluate the apical and linear sealing in different materials placed as a protective cervical barrier (BPC) in internal bleaching at Cementoenamel junction (CEJ) level and 1mm above. 112 bovine teeth were divided into seven groups according to the material to be placed as PCB and a control group, and two subgroups each in relation to their JAC level position: GRC Resin composite without adhesive system (Z250); GVR, Conventional glass ionomer cement (GIC) (VIDRION R); GVB, Lining resin modified GIC (VITREBOND); GVTR, Restorative resin modified GIC (VITREMER); GCZ, Zinc phosphate cement (CEMENTO DE ZINCO); GCT, Temporary restorative material (COLTOSOL), GCF, Light curing temporary material (CLIP F). A control group with gutta-percha and sealer cement (Fillapex) with the two positions was performed too. The teeth were bleached by walking bleach technique for seven days and then stained for 48hrs while stored at 37oC and humidity to 100%. Visual inspection was used to evaluate the specimens. Statistical analyses were performed with the two-factor analysis of variance (ANOVA-2) and Tukey test. The experimental groups showed that the main factor for apical (F=26.42, p=0.00) and linear (F=29.73; p=0.00) sealing was the type of material used regardless of their location. The experimental groups GRC and GCZ had the worst sealing values and were statistically significant different (p= < 0.05) with the other groups and the control group. The groups GCT, GCF, GVB, GVTR and GVR showed better result with no significance difference between them and the control group (p=< 0,05). The Spearman rank correlation coefficient revealed the positive significant correlation (r = 0.911, p = 0.00) between the apical and linear leakage. These results suggest that the ability of linear and apical sealing of PCB, varies according to the applied material regardless of the CEJ position.