Evaluation of primary stability in modified implants: Analysis by resonance frequency and insertion torque.

BACKGROUND: Changes in the macrogeometry of dental implants are known to influence primary stability and the osseointegration process. PURPOSE: The purpose of the present in vitro study was to evaluate the mechanical behavior of geometric changes in the apex region of dental implants. METHODS: Thirty-five cylindrical dental implants (Titamax Ti; Neodent) were machined at the apical third to reproduce the experimental groups: without apical cut (Wc), apical bi-split cut, apical tri-split cut, apical quadri-split cut (Qs). One (control group) (Titamax Ti Ex) (n = 7) without any modifications was added. The implants had the same final dimensions (4.1 x 11 mm2 ). All implants were inserted into artificial bone blocks and were evaluated by insertion torque and resonance frequency by ISQ values (Osstell). Two-tailed analysis of variance (One-way ANOVA) and Tukey's post-test (P < .05). RESULTS: Control and Qs implants showed a significant increase of the insertion torque (P < .001). For the resonance frequency, Wc and (control) implants had the greatest ISQ values. However, there's no significant difference between (control) and Qs for the ISQ values (P < .001). CONCLUSION: Within the limitations of the present study, the proposed geometries at the apical third of dental implants greatly influenced its insertion torque and primary stability in vitro.

Effect of surface treatments on the shear bond strength of luting cements to Y-TZP ceramic.

STATEMENT OF PROBLEM: Because zirconia is a glass-free material, alternative surface treatments such as airborne-particle abrasion or silica coating should be used for long-term bonding. However, these surface treatments in combination with different bonding agents and luting cements have not yet been studied. PURPOSE: The purpose of the study was to evaluate the effect of surface treatments on the shear bond strength (SBS) of luting cements to Y-TZP ceramic. MATERIAL AND METHODS: Zirconia disks (N=240) were airborne-particle abraded with the following particles (n=48): 50 µm Al2O3; 120 µm Al2O3; 30 µm silica-coated Al2O3 (Rocatec Soft); 120 µm Al2O3+110 µm silica-coated Al2O3 (Rocatec Plus); and Rocatec Plus. After silanization of the zirconia surface, composite resin disks were bonded with (n=12) RelyX Luting 2; RelyX ARC; RelyX U100; and Panavia F. The bonded specimens were thermocycled (10 000 cycles) and tested for SBS. Failure mode was determined with a stereomicroscope (×20). The morphology and elemental composition of airborne-particle abraded surfaces were evaluated with scanning electron microscopy (×500) and energy-dispersive x-ray spectroscopy (×50). RESULTS: Surface treatments, cements, and their interaction were significant (P<.001). For RelyX ARC, Rocatec Soft and Rocatec Plus provided the highest SBS. In general, surface treatments did not influence the SBS of RelyX U100 and Panavia F. Regardless of the cement, no significant difference was found between 50 µm and 120 µm Al2O3 particles, between Rocatec Soft and Rocatec Plus, or between Rocatec Plus and 120 µm Al2O3 particles+Rocatec Plus. All groups showed adhesive failures. Different particle sizes provided differences in morphological patterns. The elemental composition comprised Al and Al/Si for alumina and silica-abraded zirconia. CONCLUSIONS: Particle size did not influence the SBS of the groups abraded exclusively with alumina or silica-coated particles. RelyX ARC was more surface-treatment dependent than RelyX U100 or Panavia F.

Efeito de tratamento de superfície na composição de zircônia e na resistência de união com diferentes cimentos / Effect of surface treatments on Y-TZP ceramic surface characterization and shear bond strength to luting cements

A zircônia tetragonal policristalina estabilizada por ítria (Y-ZTP), em virtude de suas propriedades mecânicas, pode ser indicada para restaurações dento ou implantosuportadas. Porém, em função de sua composição, este material apresenta dificuldade de se unir eficazmente com os cimentos, comprometendo assim a longevidade das restaurações. O objetivo desse estudo foi avaliar a influência de diferentes tratamentos de superfície e cimentos na resistência ao cisalhamento (RC) de uma Y-ZTP, assim como a caracterização química da superfície da zircônia após os jateamentos. Duzentos e quarenta discos de Y-ZTP (5 x 2 mm) foram obtidos e aleatoriamente divididos em 5 grupos (n=40) de acordo com os tratamentos de superfície: 1) jateamento com óxido de alumínio (Al2O3) de 50 µm + silano; 2) jateamento com Al2O3 de 120 µm + silano; 3) jateamento com partículas de Al2O3 modificadas por sílica (Rocatec Soft) (30 µm) + silano; 4) jateamento com Al2O3 de 120 µm seguido do jateamento com partículas de Al2O3 modificadas por sílica (110 µm) (Rocatec Plus) e 5) Rocatec Plus + silano. Discos de resina composta (Filtek Z350 XT) foram confeccionados e imediatamente cimentados sobre a superfície da zircônia com os seguintes cimentos (n=12): 1) RelyX Luting 2; 2) RelyX ARC; 3) RelyX U100; e 4) Panavia F 2.0. Os silanos usados foram: 1) RelyX Ceramic Primer para os cimentos RelyX Luting 2, RelyX ARC e RelyX U100 e 2) Clearfil SE Bond Primer/Clearfil Porcelain Bond Activator para o cimento Panavia F 2.0. Após a cimentação, os espécimes foram armazenados por 6 dias em meio seco à 37ºC antes da ciclagem térmica (10.000 ciclos, 5 - 55ºC, 30 s/banho) para então serem submetidas ao teste de RC em máquina universal de ensaios (EMIC DL2000). Os dados foram analisados por meio de ANOVA 2 fatores e teste de Tukey ( α=0,05). Uma vez que todos os espécimes do cimento RelyX Luting 2 se soltaram durante a termociclagem, este cimento não entrou na análise estatística. As falhas foram avaliadas em lupa estereoscópica (x 20). A composição elementar dos espécimes jateados foi investigada empregando-se energy-dispersive X-ray spectroscopy (EDS). Os fatores tratamento de superfície e cimento, bem como sua interação influenciaram significativamente (P<0,001) a RC da interface zircônia/cimento. Para os três cimentos (RelyX ARC, RelyX U100 e Panavia F2.0), não houve diferença significativa entre os jateamentos com Al2O3, de 50µ e 120µ. Para o cimento RelyX ARC, os jateamentos com Rocatec Soft e Rocatec Plus promoveram a maior RC. Para os cimentos RelyX U100 E Panavia F, não houve diferença estatisticamente significante entre os tratamentos de superfície, com exceção do jateamento com Al2O3 de 120 µm, que promoveu a menor RC quando o cimento RelyX U100 foi empregado. Tanto no jateamento com Al2O3 de 50 µm quanto naquele realizado com Al2O3 de 120 µm, não houve diferença estatística entre os três cimentos. Nos jateamentos com os sistemas Rocatec Soft e Rocated Plus, os grupos cimentados com Panavia F 2.0 exibiram os menores valores de RC. No jateamento com Al2O3 de 120 µm + Rocatec Plus, o cimento RelyX ARC apresentou a menor RC. Todos os espécimes apresentaram 100% de falha adesiva. O elemento Al foi identificado nas superfícies jateadas com Al2O3 de 50 µm e 120 µm, enquanto nos espécimes jateados com partículas de Al2O3 modificadas por sílica, os elementos Al e Si foram encontrados. Concluiu-se que nenhum dos cinco tratamentos de superfície testados foi eficaz na união do cimento RelyX Luting 2 à zircônia. Para os demais cimentos, o tamanho da partícula não influenciou os valores de RC nos grupos jateados exclusivamente com Al2O3 ou partículas de Al2O3 modificadas por sílica. Os três cimentos não influenciaram a RC quando foi realizado o jateamento com Al2O3. A utilização do sistema triboquímico beneficiou mais o cimento RelyX ARC, enquanto o cimento Panavia F 2.0 foi o que menos se beneficiou dessa condição de jateamento. O jateamento com partículas de Al2O3 de 120 µm antes da aplicação do Rocatec Plus é desnecessário

Due to their excellent mechanical properties, biocompatibility, low thermal conductivity, and chemical stability, Y-TZP (yttria-stabilized tetragonal zirconia polycrystal) ceramics have been used to manufacture metal-free tooth- or implantsupported prostheses. However, the conventional surface treatments (hydrofluoric acid etching and silanization) used for silica ceramics are not effective in promoting suitable bonding between resin-based materials and zirconia. Therefore, the purpose of this in vitro study was to evaluate the effect of different surface treatments on the shear bond strength (SBS) of luting cements to yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and on its surface chemical characterization. Two hundred and forty Y-TZP discs (5 × 2 mm) were obtained and randomly divided into 5 airborneparticle abraded groups (n=48): 1) 50 µ;m Al2O3 particles; 2) 120 µm Al2O3 particles; 3) 30 µm silica-modified Al2O3 particles (Rocatec Soft); 4) 120 µm Al2O3 particles, followed by 110 µm silica-modified Al2O3 particles (Rocatec Plus); and 5) Rocatec Plus. After airborne-particle abrasion the surfaces were treated with silane coupling agent. Composite resin discs (Filtek Z350 XT) were produced and bonded immediately to the zirconia-treated surfaces (n=12) with: 1) RelyX Luting 2; 2) RelyX ARC; 3) RelyX U100; or 4) Panavia F 2.0. The silanes used were RelyX Ceramic Primer (RelyX Luting 2, RelyX ARC and RelyX U100) and Clearfil SE Bond Primer/Clearfil Porcelain Bond Activator (Panavia F 2.0). The bonded specimens were stored for 6 days in dry conditions at 37ºC before thermal cycling (10,000 cycles, 5 to 55ºC) and then tested for SBS in a mechanical testing machine (EMIC DL2000). Data were analyzed by two-way ANOVA and Tukey HSD post hoc test (α =.05). Failure mode was determined with a stereomicroscope (×20). The elemental composition of the air-abraded surfaces was obtained by energy dispersive X-ray spectroscopy (EDS) using a scanning electron microscopy (x50). The surface treatments, cements, and their interaction were significant (P<.001). For RelyX ARC, Rocatec Soft and Rocatec Plus provided the highest SBS value. For RelyX U100 (except for the group 120 µm Al2O3 particles + silane) and Panavia F, there was no significant difference among the surface treatments. For RelyX Luting 2, all groups failed spontaneously. Regardless of the cement, there was no significant difference neither between 50 µm and 120 µm Al2O3 particles nor between Rocatec Soft (30 µm) and Rocatec Plus (110 µm). Additionally, Rocatec Plus + silane and 120 µm Al2O3 particles + Rocatec Plus + silane provided statistically similar mean SBS to each other, irrespective of the cement. For the abrasion with 50 µm and 120 µm Al2O3 particles, all cements exhibited statistically similar SBS values, while for Rocatec Soft and Rocatec Plus, Panavia F provided the lowest SBS value. RelyX ARC exhibited the lowest SBS mean value among the groups abraded with 120 µm Al2O3 particles + Rocatec Plus. All groups showed a predominance of adhesive failure mode. The elemental composition comprised Al and Si. The particle size did not influence the SBS of the groups abraded exclusively with Al2O3 particles or silica-modified ones. The cement did not influence the SBS when abrasion was performed exclusively with Al2O3 particles. RelyX ARC and Panavia F were respectively the most and the least benefited cements by the tribochemical silica-coating systems. Abrasion with 120 µm Al2O3 particles before Rocatec Plus was dispensable