Morse taper implants at different bone levels: a finite element analysis of stress distribution

AIM: To explore the biomechanical effects of the different implantation bone levels of Morse taper implants, employing a finite element analysis (FEA). METHODS: Dental implants (TitamaxCM) with 4x13 mm and 4x11 mm, and their respective abutments with 3.5 mm height, simulating a screwed premolar metal-ceramic crown, had their design performed using the software AnsysWorkbench 10.0. They were positioned in bone blocks, covered by 2.5 mm thickness of mucosa. The cortical bone was designed with 1.5 mm thickness and the trabecular bone completed the bone block. Four groups were formed: group 11CBL (11 mm implant length on cortical bone level), group 11TBL (11 mm implant length on trabecular bone level), group 13CBL (13mm implant length on cortical bone level) and group 13TBL (13 mm implant length on trabecular bone level). Oblique 200 N loads were applied. Von Mises equivalent stresses in cortical and trabecular bones were evaluated with the same design program. RESULTS: The results were shown qualitatively and quantitatively by standard scales for each type of bone. By the results obtained, it can be suggested that positioning the implant completely in trabecular bone brings harm with respect to the generated stresses. Its implantation in the cortical bone has advantages with respect to better anchoring and locking, reflecting a better dissipation of the stresses along the implant/bone interfaces. In addition, the search for anchoring the implant in its apical region in cortical bone is of great value to improve stabilization and consequently better stress distribution. CONCLUSIONS: The implant position slightly below the bone in relation to the bone crest brings advantages as the best long-term predictability with respect to the expected neck bone loss

Evaluation of mass variation and surface roughness caused by the association of mechanical (brushing) and chemical (immersion) methods of denture cleanser

O objetivo deste trabalho foi avaliar a variação de massa e a alteração da rugosidade de superfície, causadas pela associação dos métodos mecânico (escovação) e químico (imersão) de higiene de próteses totais. Foram utilizados 240 corpos de prova de acrílico Plexiglass (90 x 30 x 3 mm). O ensaio de escovação (método mecânico) foi realizado em máquina de escovação (Mavtec), em frequência de 356 rpm, curso da escova (Tek Macia) de 3,8 centímetros, peso da sapata de 200 gramas e tempo de 50 minutos (simulação de 01 ano de escovação). Como suspensões, foram utilizadas água destilada e 04 dentifrícios (02 convencionais: Sorriso e Colgate; e 02 específicos para próteses totais: Polident e Corega). Após a escovação, os corpos de prova foram imersos em água destilada, hipoclorito de sódio a 0,5%, solução de mamona a 10% e Corega Tabs por 121,6 horas (simulação de 01 ano de imersão, por 20 minutos diários - ciclo curto) e 2920 horas (simulação de 01 ano de imersão, por 8 horas ao dia - ciclo longo). Foram obtidos 20 grupos (n=12), combinando as 05 substâncias utilizadas na escovação às 4 soluções utilizadas nos ensaios de imersão. A variação de massa foi avaliada pelo método Gravimétrico indireto, sendo as pesagens realizadas em balança (Metler Toledo GMbH) antes dos procedimentos de higiene (M0), após a escovação (M1), após a imersão pelo ciclo curto (M2) e após a imersão pelo ciclo longo (M3). A alteração da rugosidade de superfície (&mu;m) foi avaliada por rugosímetro (Surtronic 25), por meio da obtenção de média de três leituras (4,0 mm de comprimento e valor de \"cut-off\" de 0,8 mm, a 0,5 mm/s) antes dos procedimentos de higiene (RS0), após a escovação (RS1), após a imersão pelo ciclo curto (RS2) e após a imersão pelo ciclo longo (RS3). Os dados provenientes do método mecânico foram submetidos ao teste não paramétrico Kruskal-Wallis, seguido pelo pós-teste de Dunn (p<0,01); os dados relativos à comparação dos diferentes métodos de higiene foram submetidos ao teste de regressão linear (p<0,01). Para o método mecânico, quanto à variação de massa, entre os dentifrícios, os maiores valores foram registrados para a escovação com Sorriso (-0,0111±0,0032), enquanto os menores, para a escovação com o Polident (-0,0069±0,0023). Para a alteração da rugosidade de superfície, os maiores valores foram obtidos para a escovação com Sorriso (2,2003±1,8932), enquanto os menores, para o Corega (0,9263±0,8621). Quanto à comparação dos métodos, para a variação de massa, quando o método combinado foi realizado com imersão em hipoclorito de sódio, houve perda de massa após ambos os ciclos, enquanto que, as imersões em água destilada, mamona e Corega Tabs, acarretaram um aumento de massa. Quanto à alteração de rugosidade de superfície, não houve diferença significativa entre métodos ou entre soluções utilizadas para imersão. Conclui-se que é importante a indicação de dentifrícios específicos para próteses totais, em virtude da menor magnitude dos efeitos adversos causados, e que, a incorporação de um método químico à escovação, não causa efeitos adversos clinicamente significantes ao substrato empregadoThe aim of this study was to evaluate the mass variation and changes in surface roughness when mechanical and chemical methods of denture cleanser were associated. Two hundred and forty Plexiglass specimens (90x30x3 mm) were used. The brushing test was carried out using a toothbrushing machine (Mavtec), with a frequency of 356 rpm, course covered by brush corresponds to 3.8 cm, the load was standardized at 200 g, and length of 50 minutes (01 year of brushing). As suspensions, were utilized distilled water and 04 dentifrices (02 conventional: Sorriso and Colgate; and 02 indicated for denture cleanser: Polident and Corega). After brushing, the specimens were immersed in sodium hypochlorite (NaClO) 0,5%, Ricinus communis 10% solution and Corega Tabs for 121,6 hours (01 year of immersion, 20 minutes daily - short cycle) and 2920 hours (01 year of immersion, 8 hours daily - long cycle). Twenty groups were obtained, associating the 05 brushing solutions with the four immersion products. The specimens were weighed before the tests (M0), after the brushing test (M1), after short cycle immersion test (M2) and after the long cycle immersion test (M3) in a precision balance (Metler Toledo GMbH). The surface roughness (&mu;m) was evaluated by a rughosimeter (Surftest SJ-201P) before the tests (R0), after the brushing test (R1), after short cycle immersion test (R2) and after the long cycle immersion test (R3). The mechanical method results was submitted to Kruskal-Wallis non-parametric test, and Dunn\'s test (p<0,01); For the hygiene methods, the linear regression analysis (p<0,01) was used. For the mechanical method, the dentifrice that caused the greatest mass variation was Sorriso (-0,0111±0,0032), while the lowest variation was caused by Polident (-0,0069±0,0023). For the surface roughness, the greatest values were obtained for Sorriso (2,2003±1,8932), and the lowest, for Corega (0,9263±0,8621). For the comparison of the methods, for the mass variation, when the combined method was performed with immersion in sodium hypochlorite, there was mass loss after both combined cycles. Immersions in water, Ricinus communis and Corega Tabs, resulted in mass increase. For the surface roughness changes, there was no significant difference between methods or solutions used for immersion tests. It was concluded that it is important to indicate specific dentifrices for complete dentures, due to the small magnitude of the adverse effects, and that the incorporation of a chemical method to the brushing does not cause clinically significant adverse effect

Evaluation of weight loss and surface roughness caused by the association of mechanical (brushing) and chemical (immersion) methods of denture cleanser.

O objetivo deste trabalho foi avaliar a perda de massa e a alteração da rugosidade superficial causadas pela associação dos métodos mecânico (escovação) e químico (imersão) de higiene de próteses totais. Foram utilizados 72 corpos de prova (90 x 30 x 3 mm) de Plexiglass. O ensaio de escovação (método mecânico) foi realizado em máquina de escovação (Mavtec), em frequência de 356 rpm, curso da escova (Tek Macia) de 3,8 centímetros, peso da sapata de 200 gramas e tempo de 50 minutos (simulação de 01 ano de escovação). Como suspensões, foram utilizadas água destilada e 04 dentifrícios (02 convencionais: Sorriso e Colgate; e 02 específicos para próteses totais: Polident e Corega). Após a escovação, os corpos de prova foram imersos (hipoclorito de sódio 0,5% - NaClO) por 121,6 horas (simulação de 01 ano de imersão, por 20 minutos diários). Foram obtidos 06 grupos, sendo 01 controle (C - escovação e imersão em água) e 05 experimentais (Ex1 - água; Ex2 - Sorriso; Ex3 - Colgate; Ex4 - Polident; Ex5 - Corega; todos imersos em NaClO). A perda de massa foi avaliada pelo método Gravimétrico, sendo as pesagens realizadas em balança (Metler Toledo GMbH) antes dos procedimentos de higiene (M1), após a escovação (M2) e após a imersão (M3). A alteração da rugosidade superficial (m) foi avaliada por rugosímetro (Surftest SJ-201P), por meio da obtenção de média de três leituras (4,0 mm de comprimento e valor de &Prime;cut-off&Prime; de 0,8 mm, a 0,5 mm/s) antes dos procedimentos de higiene (R1), após a escovação (R2) e após a imersão (R3). Os resultados foram submetidos a ANOVA (dois fatores) e teste de Bonferroni. Para a perda de massa, após o ensaio mecânico, entre os dentifrícios, os maiores valores foram registrados para Ex2 (-0,0137±0,0085), Ex3 (- 0,0123±0,0038) e Ex5 (-0,0121±0,0032), e menores para Ex4 (-0,0072±0,0017); após o método combinado, os maiores valores foram obtidos para os grupos Ex2 (-0,0184±0,0040) e Ex3 (- 0,0155±0,0034), e os menores para Ex4 (-0,0108±0,0023); o método combinado resultou em maior perda de massa que o método mecânico, exceto para o grupo Ex5. Para a alteração da rugosidade superficial, após o ensaio mecânico, os menores valores foram registrados para Ex1 (-0,007±0,016) e Ex4 (0,402±0,378) e maiores para os demais; após o método combinado, os maiores valores foram obtidos para Ex2 (1,617±1,190) e Ex5 (1,634±1,082), e os menores para Ex1 (-0,063±0,013); não houve diferença entre os tratamentos. Conclui-se que: 1. A escovação com dentifrícios acarretou maior perda de massa e alteração da rugosidade que a escovação com água; 2. A imersão em NaClO 0,5% associada à escovação com dentifrícios, acarretou maior perda de massa e alteração da rugosidade, quando comparada à imersão em água; 3. O dentifrício Polident (específico) apresentou os menores valores de perda de massa e de rugosidade superficial para ambos os métodos (mecânico e combinado); 4. O método combinado não resultou em alteração da rugosidade superficial, mas acarretou maior perda de massa que o método mecânico, exceto para o dentifrício Corega (específico).The aim of this study was evaluate the weight loss and changes in surface roughness when mechanical and chemical methods of denture cleanser were associated. Seventy-two Plexiglass specimens (90x30x3 mm) were used. The brushing test was carried out using a toothbrushing machine (Mavtec), with a frequency of 356 rpm, course covered by brush corresponds to 3.8 cm, the load was standardized at 200 g, and length of 50 minutes (01 year of brushing). Like suspension, were utilized distilled water and 04 dentifrices (02 conventional: Sorriso and Colgate; and 02 indicated for denture cleanser: Polident and Corega). After brushing, the specimens were immersed in sodium hypochlorite (NaClO) 0,5% for 121,6 hours (01 year of immersion). Six groups were obtained, 01 control (C - brushing and immersion with water) and 05 experimental (Ex1: water; Ex2: Sorriso; Ex3: Colgate; Ex4: Polident; Ex5: Corega- all immersed in NaClO). The specimens were weighed before the tests (M1), after the brushing test (M2) and after the immersion test (M3) in a precision balance (Metler Toledo GMbH). The surface roughness (m) was evaluated by rugosimeter (Surftest SJ-201P) before the tests (R1), after the brushing test (R2) and after the immersion test (R3). The weight loss and roughness dates were subjected to ANOVA and Bonferroni tests (p < 0.05). After the brushing test, between the dentifrices, the greater values was registered for Ex2 (-0,0137±0,0085), Ex3 (-0,0123±0,0038) e Ex5 (-0,0121±0,0032), and the lowest for Ex4 (-0,0072±0,0017); after the association of the two methods, the grater values was obtained for Ex2 (-0,0184±0,0040) e Ex3 (-0,0155±0,0034), and the lowest for Ex4 (- 0,0108±0,0023); the association of the methods resulted in greater weight loss than the mechanical method, except for Ex5. For the surface roughness, after the mechanical test, the lowest values were registered for Ex1 (-0,007±0,016) and Ex4 (0,402±0,378), and the grater for the others; after the association of the methods, the greater values were obtained for Ex2 (1,617±1,190) and Ex5 (1,634±1,082), and the lowest for Ex1 (-0,063±0,013); there was no difference for the treatments. We conclude that: 1. Brushing with toothpaste resulted in greater weight loss and change in roughness that brushing with water. 2. The immersion in NaClO 0.5% associated with tooth brushing caused greater weight loss and change of roughness, when compared to immersion in water. 3. The toothpaste Polident (specific) had the lowest mass loss and surface roughness for both methods (mechanical and combined) 4. The association of the two methods resulted in no change in surface roughness, but in greater weight loss than the mechanical method, except for the Corega (specific)

Abrasiveness of conventional and specific denture-cleansing dentifrices

This study analyzed the weight loss and surface roughness caused in Plexiglass specimens by conventional dentifrices (Sorriso, Colgate and Close Up) and specific dentifrices used for cleaning of dentures (Corega and Dentu Creme). Plexiglass specimens were divided into 6 groups (n=6) including: a control (distilled water - DW) and experimental groups. Brushing was performed in a toothbrushing machine with a soft brush and a dentifrice suspension and DW according to different brushing times (50, 100, 200 and 250 min -18,000, 36,000, 72,000 and 90,000 cycles, respectively, calculated to correspond to 1, 2, 4 and 5 years of regular brushing). The results of weight loss and surface roughness were analyzed by ANOVA and Tukey&#8217;s test at 5% significance level. In all tested times, the effect of DW was insignificant. Dentifrices differed significantly from DW in the initial period. Corega dentifrice caused greater mass loss in all studied times, followed by Close Up. Dentifrices resulted in a surface roughness similar to the DW at 50 min. In the other times, Sorriso, Colgate and Corega caused more surface roughness than DW. In conclusion, specific dentifrices caused larger mass loss and lower surface roughness as conventional dentifrice

Morse taper implants at different bone levels: a finite element analysis of stress distribution

explore the biomechanical effects of the different implantation bone levels of Morse taper implants, employing a finite element analysis (FEA). Methods: Dental implants (TitamaxCM) with 4x13 mm and 4x11 mm, and their respective abutments with 3.5 mm height, simulating a screwed premolar metal-ceramic crown, had their design performed using the software AnsysWorkbench10.0. They were positioned in bone blocks, covered by 2.5 mm thickness of mucosa. The cortical bone was designed with 1.5 mm thickness and the trabecular bone completed the bone block. Four groups were formed: group 11CBL (11 mm implant length on cortical bone level), group 11TBL (11 mm implant length on trabecular bone level), group 13CBL (13mm implant length on cortical bone level) and group 13TBL (13 mm implant length on trabecular bone level). Oblique 200 N loads were applied. Von Mises equivalent stresses in cortical and trabecular bones were evaluated with the same design program. Results: The results were shown qualitatively and quantitatively by standard scales for each type of bone. By the results obtained, it can be suggested that positioning the implant completely in trabecular bone brings harm with respect to the generated stresses. Its implantation in the cortical bone has advantages with respect to better anchoring and locking, reflecting a better dissipation of the stresses along the implant/bone interfaces. In addition, the search for anchoring the implant in its apical region in cortical bone is of great value to improve stabilization and consequently better stress distribution. Conclusions: The implant position slightly below the bone in relation to the bone crest brings advantages as the best long-term predictability with respect to the expected neck bone loss