Effect of Polyethylene Terephthalate Tongue Scraper on Oral Levels of Volatile Sulfur Compounds: a randomized clinical trial / Efeito do raspador de língua de polietilenotereftalato nos níveis orais de compostos sulfurados voláteis: um ensaio clínico randomizado

Objective: To evaluate the effect of Polyethylene Terephthalate (PET) tongue scraper on the volatile sulfur compound (VSC) levels. Material and Methods: A randomized, controlled, parallel design was used in this study. Out of the 48 volunteers from Dentistry Department of the Federal University of Sergipe, 40 subjects who met the inclusion criteria were randomly divided into 4 groups (n=10): G1 (control), rinsing of distilled water solution (WS); G2, WS and tongue coating removal (TCR) with toothbrush; G3, WS and TCR with a commercial tongue scraper; and G4, WS and TCR with PET tongue scraper. PET bottles were cut with a rectangular shape (1.0 cm wide x 20 cm long) to obtain PET tongue scraper. The VSC measurements were performed before (T0) and immediately after (T1) each therapy by portable sulfide monitor. Data (ppb) were submitted to Wilcoxon test (α=0.05). The differences between T0 and T1 were calculated and percentage values were assigned. Data (percentage) were submitted to ANOVA and Tukey test (α=0.05). Results: All 40 selected subjects completed the study. All groups reduced significantly the VSC levels after therapy (P<0.01). ANOVA indicated a significant difference among groups (P<0.001). The Tukey test showed that G1 (reduction of 21%) was similar to G2 (31%); G2 was similar to G3 (42%) and different from G4 (52%); G3 and G4 were similar. Conclusion: PET tongue scraper was similar to commercial tongue scraper and provided higher reductions of VSC levels than the toothbrush. (AU)

Objetivo: Avaliar o efeito do raspador de língua de polietilenotereftalato (PET) nos níveis de compostos sulfurados voláteis (CSVs). Material e Métodos: Um desenho paralelo, controlado e randomizado foi empregado neste estudo. Dos 48 voluntários do Departamento de Odontologia da Universidade Federal de Sergipe, 40 atenderam ao critério de inclusão e foram distribuídos aleatoriamente em 4 grupos (n=10): G1 (controle), bochecho com solução de água destilada (SA); G2, SA e remoção da saburra lingual (RSL) com escova dental; G3, SA e RSL com um raspador de língua comercial; e G4, SA e RSL com raspador de língua PET. Garrafas PET foram recortadas com uma forma retangular (1,0 cm de largura x 20 cm de comprimento) para obtenção dos raspadores de língua PET. As mensurações de CSVs foram realizadas antes (T0) e imediatamente após (T1) cada terapia usando um monitor portátil de enxofre. Os dados (ppb) foram submetidos ao teste de Wilcoxon (α=0,05). As diferenças entre T0 e T1 foram calculadas e transformadas em valores percentuais de redução. Os dados (percentuais) foram submetidos à ANOVA e ao teste de Tukey (α=0,05). Resultados: Todos os 40 indivíduos selecionados completaram o estudo. Em todos os grupos houve redução significante dos níveis de CSVs após terapia (P<0,01). ANOVA indicou uma diferença significante entre grupos (PP<0,001). O teste de Tukey mostrou que G1 (redução de 21%) foi semelhante a G2 (31%); G2 foi semelhante a G3 (42%) e diferente de G4 (52%); G3 e G4 foram semelhantes. Conclusão: O raspador de língua PET foi semelhante ao raspador de língua comercial e proporcionou maiores reduções de CSVs do que a escova dental. (AU)

Effect of investment type and mold temperature on casting accuracy and titanium-ceramic bond.

This study evaluated the casting accuracy of crown margins and metal-ceramic shear bond strength (SBS) of pure titanium injected into casting molds made using 2 investment types at 3 mold temperatures. Sixty crown (30-degree beveled finish line) and 60 cylinder (5mm diameter × 8mm high) patterns were divided into 6 groups (n=10), and cast using a phosphate-bonded investment (P) and a magnesium oxide-bonded investment (U), at 400°C (groups P400 and U400), 550°C (groups P550 and U550) and 700°C (groups P700 and U700) mold temperatures. Crown margins were recorded in impression material, the degree of marginal rounding was measured and margin length deficiencies (µm) were calculated. Titanium-ceramic specimens were prepared using Triceram ceramic (2mm high) and SBS was tested. Failure modes were assessed by optical microscopy. Data were subjected to two-way ANOVA and Tukey's HSD test (α=0.05). For casting accuracy, expressed by marginal deficiency (µm), investment U provided more accurate results (64 ± 11) than P (81 ± 23) (p<0.001). The increase in temperature resulted in different effects for the tested investments (p<0.001), as it provided better casting accuracy for U700 (55 ± 7) and worse for P700 (109 ± 18). Casting accuracy at 700°C (82 ± 31) was significantly different from 400°C (69 ± 9) and 550°C (68 ± 9) (p<0.05). For SBS, there was no significant differences among the groups for factors investment (p=0.062) and temperature (p=0.224), or for their interaction (p=0.149). Investment U provided better casting accuracy than investment P. The SBS was similar for all combinations of investments and temperatures.

Effect of investment type and mold temperature on casting accuracy and titanium-ceramic bond

This study evaluated the casting accuracy of crown margins and metal-ceramic shear bond strength (SBS) of pure titanium injected into casting molds made using 2 investment types at 3 mold temperatures. Sixty crown (30-degree beveled finish line) and 60 cylinder (5 mm diameter × 8 mm high) patterns were divided into 6 groups (n=10), and cast using a phosphate-bonded investment (P) and a magnesium oxide-bonded investment (U), at 400°C (groups P400 and U400), 550°C (groups P550 and U550) and 700°C (groups P700 and U700) mold temperatures. Crown margins were recorded in impression material, the degree of marginal rounding was measured and margin length deficiencies (µm) were calculated. Titanium-ceramic specimens were prepared using Triceram ceramic (2 mm high) and SBS was tested. Failure modes were assessed by optical microscopy. Data were subjected to two-way ANOVA and Tukey's HSD test (α=0.05). For casting accuracy, expressed by marginal deficiency (µm), investment U provided more accurate results (64 ± 11) than P (81 ± 23) (p<0.001). The increase in temperature resulted in different effects for the tested investments (p<0.001), as it provided better casting accuracy for U700 (55 ± 7) and worse for P700 (109 ± 18). Casting accuracy at 700°C (82 ± 31) was significantly different from 400°C (69 ± 9) and 550°C (68 ± 9) (p<0.05). For SBS, there was no significant differences among the groups for factors investment (p=0.062) and temperature (p=0.224), or for their interaction (p=0.149). Investment U provided better casting accuracy than investment P. The SBS was similar for all combinations of investments and temperatures.

O objetivo neste estudo foi avaliar a precisão da fundição de margens de coroas e a resistência de união metalocerâmica do titânio puro injetado em moldes de fundição feitos com 2 tipos de revestimentos em 3 diferentes temperaturas. Sessenta copings (com linha de término em bisel de 30°) e 60 padrões em forma de cilindros (diâmetro de 5 mm e altura de 8 mm) foram separados em 6 grupos (n=10) e fundidos usando revestimento aglutinado por fosfato (P) ou revestimento aglutinado por óxido de magnésio, nas temperaturas finais do molde: 400° (grupos P400 e U400), 550° (grupos P550 e U550) e 700° (grupos P700 e U700). As margens dos copings foram registradas em material de moldagem, o grau de arredondamento marginal foi medido e as deficiências marginais (µm) foram calculadas. Os espécimes metalocerâmicos foram confeccionados com cerâmica Triceram (altura de 2 mm) e submetidos aos ensaios de resistência de união por cisalhamento. Os tipos de fratura foram avaliados em microscópio óptico. Os dados foram submetidos à ANOVA e teste de Tukey (α=0,05). Para precisão de fundição (µm), o revestimento U promoveu melhores resultados (64 ± 11) que o P (81 ± 23) (p<0,001); o aumento da temperatura do molde resultou em efeitos diferentes para os revestimentos avaliados (p<0,001), considerando que promoveu melhor precisão de fundição para U700 (55 ± 7) e pior para P700 (109 ± 18). Os valores promovidos por 700°C (82 ± 31) foram significantemente diferentes de 400°C (69 ± 9) e 550°C (68 ± 9) (p<0,05). Para resistência de união ao cisalhamento, a ANOVA não demonstrou diferença significante para os fatores revestimento (p=0,062) e temperatura (p=0,224), nem para a interação deles (p=0,149). O revestimento U promoveu melhor precisão de fundição que o revestimento P. A resistência de união ao cisalhamento foi similar para todas as combinações de revestimentos e temperaturas do molde.

Effect of casting atmosphere on the shear bond strength of a ceramic to Ni-Cr and Ni-Cr-Be alloys.

The success of metal-ceramic restorations depends on an optimal bond between metal and ceramic. This study evaluated the effect of 3 casting atmospheres on the metal-ceramic bond strength (MCBS) of 2 Ni-Cr alloys, with beryllium (Fit Cast V) and without beryllium (Fit Cast SB). Sixty acrylic resin patterns (8 mm long and 5 mm diameter) were obtained using a fluorocarbon resin matrix. Wax was used to refine the surface of acrylic resin patterns that were invested and cast in an induction casting machine under normal, vacuum, and argon atmospheres at a temperature of 1340 degrees C. The castings were divested manually and airborne-particle abraded with 100-microm aluminum-oxide. Ten castings were obtained for each group. The IPS Classic V ceramic was applied (2 mm high and 5 mm diameter). The shear bond strength was tested in a mechanical testing machine with a crosshead speed of 2.0 mm/min. The MCBS data (MPa) were subjected to 2-way analysis of variance (alpha=0.05). There was no statistically significant difference (p>0.05) between the alloys or among the casting atmospheres. Within the limitations of this study, it may be concluded that the presence of beryllium and the casting atmosphere did not interfere in the MCBS of the evaluated metal-ceramic combinations.

Correlation between metal-ceramic bond strength and coefficient of linear thermal expansion difference

The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS) of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics) and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs) of the metals and ceramics. Verabond (VB) Ni-Cr-Be alloy, Verabond II (VB2), Ni-Cr alloy, Pors-on 4 (P), Pd-Ag alloy, and IPS (I) and Duceram (D) ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length) made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length) of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01) for the MCBS test results (MPa), with PI showing higher MCBS (67.72) than the other pairs, which did not present any significant differences. The CTE (10-6 oC-1) differences were: VBI (0.54), VBD (1.33), VB2I (-0.14), VB2D (0.63), PI (1.84) and PD (2.62). Pearson's correlation test (r=0.17) was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.

Correlation between metal-ceramic bond strength and coefficient of linear thermal expansion difference.

The purpose of this study was to evaluate the metal-ceramic bond strength (MCBS) of 6 metal-ceramic pairs (2 Ni-Cr alloys and 1 Pd-Ag alloy with 2 dental ceramics) and correlate the MCBS values with the differences between the coefficients of linear thermal expansion (CTEs) of the metals and ceramics. Verabond (VB) Ni-Cr-Be alloy, Verabond II (VB2), Ni-Cr alloy, Pors-on 4 (P), Pd-Ag alloy, and IPS (I) and Duceram (D) ceramics were used for the MCBS test and dilatometric test. Forty-eight ceramic rings were built around metallic rods (3.0 mm in diameter and 70.0 mm in length) made from the evaluated alloys. The rods were subsequently embedded in gypsum cast in order to perform a tensile load test, which enabled calculating the CMBS. Five specimens (2.0 mm in diameter and 12.0 mm in length) of each material were made for the dilatometric test. The chromel-alumel thermocouple required for the test was welded into the metal test specimens and inserted into the ceramics. ANOVA and Tukey's test revealed significant differences (p=0.01) for the MCBS test results (MPa), with PI showing higher MCBS (67.72) than the other pairs, which did not present any significant differences. The CTE (10(-6) oC(-1)) differences were: VBI (0.54), VBD (1.33), VB2I (-0.14), VB2D (0.63), PI (1.84) and PD (2.62). Pearson's correlation test (r=0.17) was performed to evaluate of correlation between MCBS and CTE differences. Within the limitations of this study and based on the obtained results, there was no correlation between MCBS and CTE differences for the evaluated metal-ceramic pairs.

Effect of casting atmosphere on the shear bond strength of a ceramic to Ni-Cr and Ni-Cr-Be alloys

The success of metal-ceramic restorations depends on an optimal bond between metal and ceramic. This study evaluated the effect of 3 casting atmospheres on the metal-ceramic bond strength (MCBS) of 2 Ni-Cr alloys, with beryllium (Fit Cast V) and without beryllium (Fit Cast SB). Sixty acrylic resin patterns (8 mm long and 5 mm diameter) were obtained using a fluorocarbon resin matrix. Wax was used to refine the surface of acrylic resin patterns that were invested and cast in an induction casting machine under normal, vacuum, and argon atmospheres at a temperature of 1340ºC. The castings were divested manually and airborne-particle abraded with 100-µm aluminum-oxide. Ten castings were obtained for each group. The IPS Classic V ceramic was applied (2 mm high and 5 mm diameter). The shear bond strength was tested in a mechanical testing machine with a crosshead speed of 2.0 mm/min. The MCBS data (MPa) were subjected to 2-way analysis of variance (α=0.05). There was no statistically significant difference (p>0.05) between the alloys or among the casting atmospheres. Within the limitations of this study, it may be concluded that the presence of beryllium and the casting atmosphere did not interfere in the MCBS of the evaluated metal-ceramic combinations

O sucesso das restaurações metalocerâmicas depende da ótima união entre metal e cerâmica. Este estudo avaliou o efeito de 3 atmosferas de fundição na resistência de união metalocerâmica (RUMC) de 2 ligas de Ni-Cr, com berílio (Fit Cast V) e sem berílio (Fit Cast SB). Sessenta padrões de resina acrílica (comprimento de 8 mm e diâmetro de 5 mm) foram obtidos usando uma matriz de teflon. Foi utilizada cera para refinar a superfície dos padrões de resina acrílica que foram incluídos e fundidos em máquina de fundição por indução nas seguintes atmosferas de fundição: normal, vácuo e argônio, à temperatura de 1340ºC. As fundições foram removidas e usinadas com partículas de óxido de alumínio de 100 mm, sendo 10 fundições por grupo. Foi aplicada a cerâmica IPS Clássico V (2 mm de altura e diâmetro de 5 mm). O ensaio de cisalhamento foi realizado em máquina de ensaios mecânicos com velocidade de 2,0 mm/min. Os dados de RUMC (MPa) foram analisados por meio da análise de variância (α=0,05). Não houve diferença significante (p>0,05) entre as ligas e entre as atmosferas de fundição. Dentro das limitações deste estudo, pode-se concluir que a presença do berílio e a atmosfera de fundição não interferiram na RUMC das combinações metalocerâmicas avaliadas.

The castability of pure titanium compared with Ni-Cr and Ni-Cr-Be alloys.

STATEMENT OF PROBLEM: Titanium is the most biocompatible metal available for dental casting; however, there is great concern about its castability since this aspect of a casting metal/alloy has direct influence on the marginal fit of dental crowns. PURPOSE: The purpose of this study was to compare the castability of commercially pure titanium with 2 Ni-Cr base metal alloys. MATERIAL AND METHODS: Castability was evaluated indirectly by determining the sharpness of cast crown margins using the lost-wax technique. Castability was expressed in terms of the deficiency (mum) between an actual casting margin and a potentially perfect margin. Crown margins were recorded in a silicone impression material. The degree of marginal rounding was measured and margin length deficiencies (mum) were calculated. Sixty acrylic resin crown patterns with wax margins were prepared on a stainless steel stylized crown die having a 30-degree beveled finish line. The degree of wax margin rounding was determined in the control group (group W, n=15). The remaining 45 crown patterns were divided into 3 groups (n=15) and cast in commercially pure titanium (Tritan, group Ti), Ni-Cr-Be alloy (Verabond; group VB), and Ni-Cr alloy (Verabond II; group VBII). Margin configurations for both wax patterns and cast specimens were measured and recorded with the same method, using silicone impressions of the margins. After polymerization, the silicone material was sectioned in 8 locations through the margin area so that cross sections of the margins could be observed. Marginal deficiency was determined using microscopic measurements from the silicone sections and calculations. Data were subjected to 1-way ANOVA and Tukey HSD test (alpha=.05). RESULTS: Statistical analysis showed significant differences among the groups W, Ti, VB, and VBII (P<.001). The Tukey test revealed that Ti (108 +/-26 microm) was not significantly different from VBII (95 +/-35 microm), but was significantly different than Groups VB (22 +/-5 microm) and W (19 +/-6 microm), which were similar. CONCLUSIONS: Within the limitations of this study, the castability of titanium was poor compared to Ni-Cr-Be alloy, but similar to Ni-Cr alloy.

Effect of the use of die spacer on the marginal fit of copings cast in NiCr, NiCrBe and commercially pure titanium.

The goal of this study was to evaluate the effect of using die spacers on the marginal fit of NiCr (M1) and NiCrBe (M2) alloys and commercially pure titanium (cpTi) (M3) copings cast by the lost wax technique. Using a metal matrix, 45 resin added extra hard type IV stone models were obtained for the fabrication of wax patterns under the following conditions: no die spacer (A), with one die spacer layer (B) and with two die spacer layers (C), with five repetitions for each condition (alloy x die). Each die was waxed and the wax patterns were invested as per manufacturer's instructions. Three wax patterns were embedded in each casting ring, each corresponding to one of the conditions. Each coping, seated to the metal matrix by a seating pressure standardizing device (SPSD), was taken to an optical microscope for measurement of marginal discrepancy. The obtained data (microm) were analyzed statistically by ANOVA and Tukey' test (a=5%). There was statistically significant difference (p<0.05) among the materials (M1=110.67; M2=130.33 and M3=148.33). Regarding the use of the die spacer, there was a statistically significant difference (p<0.05) among the three conditions (A=162.00; B=131.06 and C=96.67). It was concluded that there is less marginal discrepancy with two die spacer layers.

Effect of the use of die spacer on the marginal fit of copings cast in NiCr, NiCrBe and commercially pure titanium

The goal of this study was to evaluate the effect of using die spacers on the marginal fit of NiCr (M1) and NiCrBe (M2) alloys and commercially pure titanium (cpTi) (M3) copings cast by the lost wax technique. Using a metal matrix, 45 resin added extra hard type IV stone models were obtained for the fabrication of wax patterns under the following conditions: no die spacer (A), with one die spacer layer (B) and with two die spacer layers (C), with five repetitions for each condition (alloy x die). Each die was waxed and the wax patterns were invested as per manufacturer's instructions. Three wax patterns were embedded in each casting ring, each corresponding to one of the conditions. Each coping, seated to the metal matrix by a seating pressure standardizing device (SPSD), was taken to an optical microscope for measurement of marginal discrepancy. The obtained data (µm) were analyzed statistically by ANOVA and Tukey' test (a=5 percent). There was statistically significant difference (p<0.05) among the materials (M1=110.67; M2=130.33 and M3=148.33). Regarding the use of the die spacer, there was a statistically significant difference (p<0.05) among the three conditions (A=162.00; B=131.06 and C=96.67). It was concluded that there is less marginal discrepancy with two die spacer layers.

O objetivo deste trabalho foi avaliar o efeito do uso de espaçadores na adaptação marginal de "copings" de ligas de NiCr (M1) e NiCrBe (M2) e titânio (M3) fundidos pela técnica de cera perdida. A partir de uma matriz metálica, foram obtidos 45 troquéis de gesso resinado tipo IV para confecção dos padrões de cera nas seguintes condições: sem a presença de espaçador (A), com uma camada de espaçador (B) e com duas camadas de espaçador (C), com cinco repetições para cada condição (liga x espaçador). Foi realizado o enceramento de cada troquel e os padrões de cera foram incluídos no revestimento indicado pelo fabricante. Em cada anel de fundição foram incluídos 3 padrões de cera, sendo cada um correspondente a cada condição. Cada "coping", adaptado à matriz metálica por meio de um dispositivo padronizador da pressão de assentamento, foi levado ao microscópio óptico para aferição das medidas da desadaptação marginal. Os dados obtidos (µm) foram submetidos à análise estatística por ANOVA e teste de Tukey (a=5 por cento). Entre os materiais houve diferença estatisticamente significante (M1=110,67, M2=130,33 e M3=148,33). Em relação ao fator espaçador, houve diferença estatisticamente significante entre as três condições (A=162,00; B=131,06 e C=96,67). Conclui-se que a presença de duas camadas de espaçador propicia menor desadaptação marginal.

Influence of investment type and sprue number on the casting accuracy of titanium crown margins.

STATEMENT OF PROBLEM: Titanium offers biocompatibility and adequate mechanical properties for fabricating dental prostheses; however, casting difficulties can compromise the accuracy of titanium crown margins. PURPOSE: The aim of this study was to evaluate the influence of investment type and number of sprues on accuracy of crown castings made with commercially pure titanium. MATERIAL AND METHODS: The casting accuracy was evaluated indirectly by determining the deficiency of titanium crown margins cast using the lost-wax technique. Crown margins were recorded in a silicone impression material. The degree of marginal rounding was measured and margin deficiencies were calculated. Seventy-five acrylic resin crown patterns with wax margins were prepared on a stainless steel stylized crown die having a 30-degree beveled finish line. Fifteen patterns were selected for the control group, and the degree of wax margin rounding was determined (group W, control). The remaining 60 were divided into 4 groups of 15 each, and cast using 2 different titanium investments: a monoammonium dihydrogenphosphate-bonded investment (Rematitan Plus; groups PI and PII), and a magnesium oxide-bonded investment (Rematitan Ultra; groups UI and UII). Each pattern was cast with either 1 (groups PI and UI) or 2 (groups PII and UII) sprues. Margin configurations for both wax pattern and cast specimens were measured and recorded with the same method, using silicone impressions of the margins. After polymerization, the silicone material was sectioned precisely in 8 locations through the margin area so that cross-sections of the margins could be observed. Marginal deficiency was determined using microscopic measurements from the silicone patterns and calculations. Data were subjected to 2-way analysis of variance (alpha=.05). RESULTS: Specimens from group W presented a mean marginal deficiency of 19 +/- 6 microm. The analysis of variance indicated a significant difference for the main factors, investment (P<.01) (P=91 +/- 28 microm and U=78 +/- 17 microm) and sprue number (P<.001) (I=97 +/- 23 microm and II=72 +/- 16 microm), as well as for interaction (P<.05) (PI=109 +/- 25 microm; PII=73 +/- 17 microm; UI=85 +/- 15 microm; and UII=71 +/- 16 microm). CONCLUSION: Within the limitations of this study, investment U provided better casting accuracy than investment P. Two sprues provided more accurate results than 1 sprue; however, this effect was more notable for investment P, as it produced similar results between groups PII and UII.