Aim: To evaluate the bond strength of brackets bonded after different surface treatments on two dental ceramics. Methods: One hundred and twenty discs (5 mm thick and 7 mm diameter) of two ceramic types were made and randomly divided in 8 groups. Groups 1, 3, 5, and 7 used Eris ceramic and groups 2, 4, 6, and 8 used d.Sign ceramic. The ceramic surfaces were treated with 10% hydrofluoric acid (G1 and G2), 10% hydrofluoric acid + silane (G3 and G4), aluminum oxide blasting + 35% phosphoric acid + silane (G5 and G6), CoJet blasting + 35% phosphoric acid + silane (G7 and G8). Metallic brackets were cemented with Concise cement. Mechanical test was performed in a universal testing machine until failure. Results: The average values (MPa) obtained (G1 -7.30; G2 -6.12; G3 -17.49; G4 -19.54; G5 -18.80; G6 -21.93; G7 -6.81 e G8 -9.77) were submitted to ANOVA and Tukey test (p<0.05). The fracture patterns were analyzed in stereoscopic microscope (25´X) and representative samples of each group were analyzed in SEM. Conclusions: It was possible to conclude that use of silane after hydrofluoric acid increased the bond strength values.

PhD.%Dental%School,%University%of%Southern%Santa%Catarina%-%UNISUL.%Tubarão,%SC,%Brazil*% PhD.%Dental%School,%University%of%Southern%Santa%Catarina%-%UNISUL.%Tubarão,%SC,%Brazil**% PhD.%Bauru%Dental%School%B%University%of%Sao%Paulo%-%USP.%Bauru,%SP,%Brazil***% PhD.%Dental%School,%University%of%Southern%Santa%Catarina%-%UNISUL.%Tubarão,%SC,%Brazil****% PhD.%Bauru%Dental%School%B%University%of%Sao%Paulo%-%USP.%Bauru,%SP,%Brazil*****%% Received%27%June%2012%Received'in'revised'form%27%November%2012%Accepted%4%December%2012% % PEREIRA,%Jefferson%Ricardo*% GHIZONI,%Janaina%Salomon**% ROSSETTI,%Paulo%Henrique%Orlato***% MAY,%Naudy%Brodbeck****% VALLE,%Accácio%Lins*****% ' ' % % % % IMPERFECTIONS'IN'PLASTER' SURFACES'CAUSED'BY'THE'RELEASE' OF'HYDROGEN'GAS'OF' POLYVINYLSILOXANE'IMPRESSION' MATERIALS%% % ABSTRACT' % PURPOSE:%The%purpose%of%this%study%was%to%evaluate%the%number%of% bubbles% of% hydrogen% liberation% from% different% polyvinylsiloxane% impression% materials.% MATERIAL' AND' METHODS:% A% metallic% stainless% steel% jig% containing% six% receptacles,% like% trays,% was% constructed% to% accommodate% the% impression% materials.% The% molds% were%poured%immediately,%and%at%1%hour,%12%hours%and%24%hours%in% order% to% evaluate% the% number% of% bubbles% present% in% each% sample.% Each% sample% was% made% of% improved% stone% (type% IV),% totaling% 48% samples% for% each% polyvinylsiloxane% impression% material.% After% setting,% the% surface% of% each% sample% was% inspected% under% a% light% microscope% at% 40x% magnification% and% the% number% of% bubbles% was% recorded.%Results%were%submitted%to%statistical%analysis%by%ANOVA% and%Tukey%Test%(p=.05).%RESULTS:%ANOVA%test%showed%statistically% significant% differences% among% the% polyvinylsiloxane% impression% materials,% as% determined% by% the% number% of% bubbles% (p<.05).% The% Tukey% test% showed% statistically% significant% differences% among% the% three% groups% (p<.05).% CONCLUSIONS:% Statistical% differences% were% found% between% addition% silicone% with% regard% to% the% ideal% time% to% wait% for% the% plaster% cast,% showing% that% Aquasil% results% in% fewer% bubbles% in% plaster,% followed% by% the% President% and% Simply% Perfect% samples.% ' ' ' ' ' ' ' ' ' ' ' KEYWORDS' % Dental%impression%materials.%Dental%impression%technique.%Hydrogen.%% Silicone%elastomers.%