교정용 브라켓에 가해지는 힘의 방향에 따른 결합강도의 비교

이현정,이형순,전영미,김정기 대한치과교정학회 2003 대한치과교정학회지 Vol.33 No.5

본 연구는 교정용 금속 브라켓에 다양한 방향에서의 복합적인 응력을 가하여 힘의 방향과 적용점에 따른 교정용 브라켓의 결합강도를 비교하고, 브라켓의 유지력을 평가하는데 기준이 되는 최소결합강도의 특성에 대해 알아보고자 시행되었다. 일정한 표면특성을 갖는 금속봉에 Micro-Loc base, Chessboard base, Non-etched Foil-Mesh base 등 서로다른 기저면 형태를 가지는 3가지 종류의 금속 브라켓을 부착시키고, 0˚, 15˚, 30˚, 45˚, 60˚, 75˚, 90˚의 peel 결합강도(_(0)PBS, _(15)PBS, _(30)PBS, _(45)PBS, _(60)PBS, _(75)PBS, _(90)PBS 및 전단결합강도(SBS)와 인장결합강도(TBS)에 대한 브라켓의 결합강도를 측정하고, 각 브라켓의 기저면 면적을 고려하여 단위면적당 결합강도를 산출하여 비교한 결과 다음과 같은 결론을 얻었다. 1. Micro-Loc base와 Chessboard base 및 Non-etched Foil-Mesh base 브라켓 모두에서 전단결합강도(SBS)가 가장 컸다(p<0.01). 2. Peel 응력의 방향 변화에 따른 peel 결합강도(PBS)의 변화양상은 Micro-Loc base와 Chessboard base, Non-etched Foil-Mesh base 브라켓 모두에서 유사하였으며(p>0.05), peel 응력의 적용 각이 증가할수록 peel 결합강도(PBS)는 감소하였고 60˚에서 최저값을 보였다(p<0.05). 3. Micro-Loc base에서 최저 peel 결합강도(_(60)PBS)는 전단결합강도(SBS)의 29% 수준이었으며, 인장결합강도(TBS)에 대해서는 52% 수준이었고, Chessboard base에서 최저 peel bond strength(_(60)PBS)는 전단결합강도(SBS)의 34% 수준이었으며, 인장결합강도(TBS)에 대해서는 61% 수준이었으며, Non-etched Foil-Mesh base에서 최저 peel 결합강도(_(60)PBS)는 전단결합강도(SBS)의 34% 수준이었으며, 인장결합강도(TBS)에 대해서는 55% 수준이었다. 4. 단위면적당 결합강도에 있어서 전단결합강도(SBS)와 인장결합강도(TBS) 및 75˚와 90˚ peel 결합강도는 Micro-Loc base와 Chessboard base에서 차이가 없었으며 Non-etched Foil-Mesh base에서 가장 작았고(p<0.05), 0˚, 15˚, 30˚, 60˚ peel 응력을 적용한 결과 Chessboard base에서 가장 큰 peel 결합강도를, Non-etched Foil-Mesh base에서 가장 작은 결합강도를 보였다(p<0.05). The purpose of this study was to evaluate the bond strength of orthodontic brackets bonded to metal bar with chemically cured adhesive (Ortho-one, Bisco Co, USA) in various types and directions of force application. Three types of metal bracket with different bracket base configurations; Micro-Loc base(Tomy Co, Japan), Chessboard base(Daesung Co, Korea), Non-etched Foil-Mesh base(Dentaurum, Germany); were used in this study. Peel, shear, tensile bond strengths were measured by universal testing machine and compared each other. The peel force directions applied were 0˚, 15˚, 30˚, 45˚, 60˚, 75˚, 90˚. And then, in consideration of the different surface area of the bracket bases, the bond strength per unit area were calculated and compared. The results obtained were summarized as follows : 1. The bond strengths according to the types and the directions of the forces were greatest at the shear forces in all three bracket base configuration groups(p<0.01). 2. As the peel force direction grew higher in degree, peel bond strength decreased. The patterns of peel bond strength change according to force direction was similar in all three bracket base configurations. The minimum bond strength was 60 degree-peel bond strengths in all three bracket base configurations. 3. In Micro-Loc base group, minimum peel bond strength(_(60)PBS) was in 29% level of shear bond strength and 52% level of tensile bond strength. In Chessboard base group, _(60)PBS was in 34% level of shear bond strength and 61% level of tensile bond strength. In Non-etched Foil-Mesh base group, _(60)PBS was in 34% level of shear bond strength and 55% level of tensile bond strength. 4. The bond strengths per unit area were lowest in Non-etched Foil-Mesh base group and highest in Chessboard base group(p<0.05). However, there were no differences in shear bond strength, tensile bond strength, _(75)PBS and _(90)PBS per unit area between Micro-Loc and Chessboard base groups.

열적, 기계적 피로응력이 교정용 브라켓의 결합강도에 미치는 영향

김정기,김상철 대한치과교정학회 2000 대한치과교정학회지 Vol.30 No.5

본 연구는 열적 및 기계적 피로응력이 교정용 브라켓의 전단결합강도, 인장결합강도, 전단-인장 복합 결합강도에 미치는 영향과 결합상태에 미치는 영향, 그리고 접착파절 양상을 비교하는데 목적이 있다. 이를 위하여 기저부 형태가 다른 5종의 금속 브라켓을 교정치료를 목적으로 발거한 상 · 하악 소구치에 부착하여, 계면에 200g의 전단-인장 복합 하중을 4주간 가한 기계적 피로시험과, 5,000회의 thermocycling을 시행한 열적 피로시험 후, 전단결합강도, 인장결합강도, 및 전단-인장 복합 결합강도를 측정하고, 파절양상을 분석하여 다음과 같은 결과를 얻었다. 1.정적시험에서 얻은 브라켓 접착부의 결합강도는 Photoetched base가 가장 크고, Integral base가 가장 작았다(p〈0.05). 모든 종류의 브라켓에서 전단결합강도가 가장 컸으며, 전단-인장 복합 결합강도는 전단결합강도의 1/3 수준으로 가장 작았다. 2.4주간 200g의 전단-인장 복합 하중을 가한 후의 결합강도는 Photoetched base가 가장 크고, Integral base가 가장 작았으며(p〈0.05), 기계적 피로시험 후 Photoetched base와 Micro-Etched Foil Mesh base의 전단, 인장, 전단-인장 복합 결합강도가 감소하였고, Chessboard base의 전단결합강도가 감소하였다(p〈0.05). 3.5,000회의 thermocycling 후의 결합강도는 Photoetched base가 가장 컸고, Integral base가 가장 작았으며 (p〈0.05), 열적 피로시험 후 Photoetched base와 Chessboard base, Micro-Etched Foil Mesh base의 결합강도가 모두 감소하였다(p〈0.05). 4.정적시험의 결합강도 측정 후 접착파절은 브라켓/레진 계면에서 일어났으며, thermocycling 후에는 브라켓/레진 계면과, 법랑질/레진 계면, 레진내 파절이 혼합되어 나타나 ARI점수가 높아졌다. 기계적 피로시험 후에는 정적시험 때와 비슷한 ARI 점수를 보였다. 5.모든 브라켓에서 thermocycling 후 브라켓/레진 계면과 법랑질/레진 계면에서 미세 균열이 관찰되었다. The purpose of this study is to evaluate the effects of mechanical and thermal fatigue stress on the shear, tensile and shear-tensile combined bond strengths(SBS, TBS, CBS) in various orthodontic brackets bonded to human premolars with chemically cured adhesive(Ortho-one, Bisco, USA). Five types of commercially available metal brackets with various bracket base configurations of Photoetched base(Tomy, Japan), Non-Etched Foil Mesh base(Dentaunlm, Germany), Micro-Etched Foil Mesh base(Ortho Organizers, USA), Chessboard base(Daesung, Korea), and Integral base(3M United, USA) were used. Samples were divided into 3 groups, the first group was acted with shear-tensile combined loads(45˚) of 200g for 4 weeks(mechanical fatigue stress), the second group was subjected to the 5,000 thermocycles of 15 second dwell time each in 5℃ and 55℃ baths(thermal fatigue stress), and the third group was the control. Bond strengths were measured at the crosshead speed of 0.5mm/min. The cross-section of bracket base/adhesive interface and the fracture surface were examined with the stereoscope and the scanning electron microscope. The resin remnant on bracket base surface was assessed by ARI(Adhesive Remnant Index). The obtained results were summarized as follows ; 1.In static bond strength, Photoetched base bracket showed the maximum bond strength and Integral base bracket showed the minimum bond strength(p〈0.05). In all brackets, shear bond strength(SBS) was in the greatest value and shear-tensile combined strength(CBS) was in the least value(p〈0.05). 2.After mechanical fatigue test, Photoetched base bracket showed the maximum bond strength and Integral base bracket showed the minimum bond strength(p〈0.05). In Photoetched base bracket and Micro-Etched Foil Mesh base bracket, shear bond strength(SBS), tensile bond strength(TBS) and shear-tensile combined strength(CBS) were decreased after mechanical fatigue test(p〈0.05). 3.After thermocycling, Integral base bracket showed the minimum bond strength. The SBS, TBS and CBS of Photoetched base, Chessboard base, and Micro-Etched Foil Mesh base bracket were decreased after 5,000 cycled thermocycling(p〈0.05). 4.In static test, bond failure sites were mainly between bracket and adhesive. After thermocycling, ARI scores were greater than those in static test. 5.SEM micrographs of cross-section of bracket bonding site showed that many micro-cracks in bracket/resin interface and in enamel/resin interface were found in all brackets after thermocycling.

A Study on Bracket-Adhesive Combinations in Aspect of Shear Bond Strength and Bond Failure

Han, Jae-Ik,Son, Woo-Sung 대한치과교정학회 1998 대한치과교정학회지 Vol.28 No.6

적절한 전단접착강도를 가지면서 법랑질손상과 브라켓파절을 적게 일으키는 브라켓-접착제의 그룹을 찾아내기 위하여 전단접착강도, 법랑질손상, 브라켓탈락양상, 브라켓 주위의 밀봉과 법랑질-접착제-브라켓 사이의 긴밀도를 연구하였다. 교정치료목적으로 발치한 240개의 치아를 각각 10개씩 24개 군으로 나누어서 브라켓을 접착한 후 48시간후에 전단접착강도를 측정하고 브라켓 탈락 양상을 조사하였다. 또한 브라켓주위의 밀봉과 법랑질-접착제-브라켓 사이의 긴밀도를 평가하기 위해서 브라켓이 접착된 치아를 반으로 자른후 주사전자현미경상에서 관찰하였다. 6종류의 브라켓과 4종류의 접착제가 사용되었으며 브라켓은 Image, Plastic, Crystaline, Fascination, Transcend, metal bracket을 사용하였으며 접착제로는 No-mix, Light-Bond, OrthoLC, Superbond C&B가 사용되었다. 이와같은 연구로 부터 다음과 같은 결론을 내렸다. 1. 전단접착강도는 Fascination-Light Bond 군에서 36.58Kg(410.07Kg/㎠)으로 가장 높았으며 Image-OrthoLC군에서 8.93Kg(75.51Kg/㎠)으로 가장 낮았다. OrthoLC를 접착제로 사용하였을 때 전단접착강도는 다른 접착제를 사용하였을 때 보다 비교적 낮았다. 2. 접착제의 종류에 관계없이 Fascination bracket의 전단접착강도는 비교적 높았으며 Image, Plastic bracket의 전단접착강도는 비교적 낮았다. Crystaline, Transcond bracket의 전단접착강도는 metal bracket의 전단접착강도와 비슷하거나 낮았다. 3. 전단접착강도와 법랑질 파절, 브라켓 파절은 상관관계가 있었으며, 접착강도가 증가할수록 법랑질 파절과 브라켓 파절은 증가하였다. 4. OrthoLC를 접착제로 사용하였을 때 법랑질 파절과 브라켓 파절은 일어나지 않았으나 Superbond C&B를 접착제로 사용하였을 때는 법랑질 파절과 브라켓 파절의 빈도가 높았다. 5. No-mix, Light-Bond를 접착제로 사용하였을 때 브라켓 주위의 밀봉과 법랑질-접착제-브라켓의 긴밀도는 양호하였다. 접착제의 종류에 관계없이 Ceramic bracket에서 접착제-브라켓의 긴밀도는 양호하였다. 6. 적절한 전단접착강도를 가지면서 법랑질 파절과 브라켓 파절을 일으키지 않은 군은 Crystaline-No mix, Crystaline-Light Bond, Crystaline-OrthoLC, metal-No mix, metal-Light Bond, metal-OrthoLC 군이였다. The purpose of the present study was to seek bracket-adhesive combinations which have adequate bond strength with no enamel and bracket fracture. The shear bond strengths were measured, the sites of failure and the enamel damage were investigated and the peripheral sealing and adaptation between enamel surface, bonging adhesive and bracket were evaluated, 240 noncarious human premolars were divided into twenty four groups of ten teeth. Shear bond strengths of each group were determined in an universal testing machine after two days passed and the debonded specimens were inspected to determine the predominant bond failure sites. To evaluate peripheral sealing and adaption between enamel surface adhesive and bracket, each specimen was cut longitudinally into two halves which included the midsection of the bracket, adhesive and enamel and examined in scanning electron microscope. Six different types of brackets were bonded to the tooth with four different type of adhesives. Six different types of brackets were Image, Plastic, Crystaline, Fascination, Transcend 2000 and metal bracket and four different adhesives were No-mix, Light-Bond, OrthoLC and Superbond C&B. From this study, it may be concluded that(1) The mean shear bond strength varied from a high of 36.58Kg(410.07Kg/㎠) with the Fascination-Light Bond combination group to a low 8.93Kg(75.51Kg/㎠) with the Image-OrthoLC combination group. When using OrthoLC as adhesive, the mean shear bond strength was significantly lower than that of other combination groups, (2) Regardless of adhesives, the mean shear bond strength of Fascination brackets was relatively high whereas Plastic and Image brackets had low shear bonding strength. The shear bond strength of Crystaline bracket and Transcend 2000 was relatively equal to or lower than that of metal bracket, (3) There was a correlation between bond strength, enamel damage and bracket fractrue. As the shear bond strength was increased, the rate of enamel damage and bracket fractrue were increased, (4) The combination groups that use OrthoLC as adhesive were debonded in shear stress without enamel fracture and bracket fracture, whereas the combination groups that use Superbond C&B as adhesive experienced a relative high enamel fracture rate and bracket fracture rate, (5) Peripheral sealing and adaptation between enamel-adhesive-bracket were relatively good when using Light-Bond or No-Mix as adhesive, Regardless of adhesives, adaptation between bracket-adhesive were relatively good in Ceramic brackets, (6) The combination groups which had adequate bonding strength with no enamel and bracket fracture were Crystaline-No mix, Crystaline-Light Bond, Crystaline-OrthoLC, metal-No mix, metal-Light Bond and metal-OrthoLC combination groups.

Analysis of in-situ bond strength of bonded concrete overlay

Rith Makara,Kim Young Kyu,Lee, Seung Woo,Park Jun Young,Han Seung Hwan 한국도로학회 2015 한국도로학회 학술발표회 논문집 Vol.2015 No.3

More than sixty percent of highways in Korea were constructed with concrete pavement to carry the heavy traffic loads due to the economic development of this country. The service life of some pavements are close to the end, therefore, they requires the maintenances, rehabilitations and reconstructions to improve their structural performances.According to the similarity of material properties to the concrete pavement, bonded concrete overlay isa good rehabilitation technique used steadily in Korea. However, it is recently reported that the bonded concrete overlays in some highways expose the early distresses and it is assumed that the poor bonding is a cause of this problem. Additionally, the poor bonding of bonded concrete overlay is caused by the bond strength that is less than the bond strength criterion. The pre-investigation of various concrete overlays is conducted in laboratory to determine the possible influence factors reducing the bond strength and it indicates that there are two possible factors affecting the bond strength: the concrete overlay types and the substrate conditions. The study investigates the vulnerable factor between the two factors based on theevaluation of the in-situ bond strength data of bonded concrete overlay gathered from some highways in Korea. The bond strength data is collected from two different application areas: the new constructionand the rehabilitation projects. The new construction and the rehabilitation projects used Latex-modified Concrete (LMC) and Ultra-rapid Hardening Latex-modified concrete (URH-LMC), respectively as the concrete overlay. The evaluation of in-situ bond strength is to determine the percentage of unacceptable bond strength in each projectto study the effect of different types of concrete overlay. Moreover, the percentage of bonding failure modes having the bond strengths less than the criterion is also measured to study the effect of substrate condition.As a result, substrate condition is the vulnerable factor affecting the poor bonding and causing the early distresses in bonded concrete overlay.

접착식 콘크리트 덧씌우기의 부착강도 특성 분석

박종원,김영규,이승우,한승환 한국도로학회 2013 한국도로학회논문집 Vol.15 No.4

PURPOSES : Bonded concrete overlay is a favorable maintenance method since the material properties are similar to existing concrete pavements. In addition, bonded concrete overlay has advantage of structural performance since the overlay layer and the existing pavement perform as a monolithic layer. It is important to have suitable bond strength criteria to secure the performance of bonded concrete overlay. This study aimed to investigate the factors influencing bond strength characteristics between existing concrete pavement and overlay material. METHODS: Bond strength between overlay and existing pavement are measured and analyzed for various conditions such as the type of overlay materials, compressive and flexure strength of overlay and existing pavement, and deterioration status of existing pavement. RESULTS: The strength of overlay material does not significantly influence the bond strength. The overlay of ultra-rapid hardening cement generally gives low bond strength. However, ultra rapid hardening polymer modified concrete gives robust bond strength. The deterioration of existing concrete significantly decrease the bond strength. CONCLUSIONS: Bond strength of bonded concrete overlay highly depends on condition of existing concrete pavement rather than overlay material.

고성능 Belite 시멘트 콘크리트의 철근 부착성능

김상준,조필규,허준,최완철,Kim, Sang-Jun,Cho, Pil-Kyu,Hur, Jun,Choi, Oan-Chul 한국콘크리트학회 1998 콘크리트학회지 Vol.10 No.6

고성능 belite 시멘트 콘크리트에 대한 부착특성에 대하여 코\ulcorner리트의 강도, 슬럼프, 배근위치, 피복두께 등의영향요인을 보단부시험체와 이음길이 보시험체를 통해 연구하였다. 동일한 압축강도의 1종 보통 포틀랜드 시멘트 콘크리트에 비해 부착강도는 약 10%증가하였고 압축강도 600kg/$\textrm{cm}^2$의고강도 belite 콘크리트에서 부착강도가 대체로 {{{{ SQRT { f'c} }} }}에 비례하였다. 유동성에 있어서 높은 슬럼프에 비해 ACI 318-95 규준에서 제시하는 상부근 계수 1.3이하의범위에 있었으며 이것은 고유동 belite 콘크리트가 블리이딩이나 골재분리가 적은 것으로 보여졌다. 또한 고강도 belite시멘트 콘크리트를 사용한 이음길이 보시험체에서 부착강도는 기존 예측식의 값보다다소 높게 나타났으며, 실리커흄, 플라이애쉬를 사용한 고강도 콘크리트 부착강도의 기존연구결과인 낮은 값과 차이를 보였다. 이상의 결과로 고유동, 고강도 belite 시멘트 콘크리트는 철근과의 부착성능이 다른 재료에 비해 양호한 것으로 나타났다. Bond strength of reinforcing bar to high-perfomance concrete using belite cement is explored using beam end test specimens. The key parameters for the bond test are slump of concrete, top bar effect, and strength of concrete in addition to concrete cover. The test results show that the specimens with belite cement concrete show approximately 10% higer bond strength than those with portland cement concrete. The results also show that the bond strength from the high strength concrete is function of the square root of concrete compressive strength. Bond strength of the top bar is less than bond strength of bottom bar, but the ratios of the bond strength of bottom-cast bars to those for top-cast bars are much less than the modification factor for top reinforcement found in the ACI 318-95 code. Comparisons with other reported tests identified that belite cement increased bond strength while silica fume or flyash used in high strength concrete decreased bond strength. The high-strength and high-slump concrete with belite cement performs well in terms of bond strength to reinforcing steel.

Plasma arc light를 이용한 bracket 부착시의 전단결합강도와 파절양상의 유형

박영철,유형석,오영근,이승연 대한치과교정학회 2001 대한치과교정학회지 Vol.31 No.2

본 연구의 목적은 bracket 부착시 광조사시간을 획기적으로 감소시킬 수 있는 plasma arc licht의 임상적 유용성을 visible light 중합시의 전단결합강도와 접착파절양상과 비교해 봄으로써 평가해 보는데 있다. 사람의 상하악 소구치를 포매하여 만든 레진블럭시편에 광중합 접착제인 TransbondR를 사용하여 수종의 bracket을 각각의 조건에 따라 부착한 후 만능 물성시험기를 이용하여 전단결합강도를 측정하고, 접착파절양상을 stereoscope을 이용하여 관찰하여 다음과 같은 결과를 얻었다. 1.Plasma arc light를 이용한 수종의 bracket 접착시 metal bracket과 ceramic bracket의 전단결합강도는 임상적으로 사용하기에 충분한 값을 나타내었으며, resin bracket의 경우 다른 bracket에 비해 전단결합강도가 현저히 작은 값을 나타내었지만 임상적으로 사용이 가능한 값을 나타내었다. 2.Visible light를 이용한 metal bracket의 광중합시 광조사시 간에 따른 전단결합강도는 광조사 시 간에 따른 유의 한 차이를 보이지 않았으며, 임상적으로 사용하기에 충분한 강도를 나타내었다. 3.Plasma arc light를 이용한 수종의 bracket 접착시 접착제 잔류지수를 통해 접착파절양상을 관찰한 결과, metal bracket과 resin bracket의 경우 bracket기저면에 접착제가 반 이상 남아 있지 않은 경우가 많았으며, ceramic bracket의 경우 bracket기저면에 접착제가 반 이상 남아 있는 경우가 많았다. 4.Metal bracket의 부착시 plasma arc light를 2초간 광조사한 군과 visible light를 10초간 광조사한 군의 전단결합강도와 접착파절양상을 비교시 유의한 차이를 보이지 않았다. 6.Plasma arc light를 이용한 광중합시 광조사 거리에 따른 전단결합강도는 거리가 증가할수록 감소하였다. 이상의 실험 결과는 plasma arc light를 이용한 bracket의 접착시 전단결합강도 저하의 우려 없이 임상적으로 사용 가능함을 시사한다. The puruose of this study was to evaluate the clinical usefulness of plasma arc light which can reduce the curing time dramatically compared by shear bond strengths and failure patters of the brackens bonded with visible light in direct bracket bonding. Some kinds of brackets were bonded with the TransbondR to the human premolars which were embedded in the resin blocks according to the various conditions. After bonding, the shear bond strength was tested by Instron universal testing machine and in addition , the amount of residual adhesive remaining on the tooth after debonding was measured by the stereoscope and assessed with adhesive remnant index(ARI). The results were as follows : 1.When plasma arc light was used for bonding the brackets, the shear bond strength was clinically sufficient in both metal and ceramic brackets, but resin brackets showed significantly lower bond strength but which was clinically useful. 2.When metal brackets were bonded using visible light, there was no significant difference in shear bond strength due to the light-curing time and the bond strength was clinically sufficient. 3.When the adhesive failure patterns of brackets bonded with plasma arc light were observed by using the adhesive remnant index, the bond failure of the metal and resin bracket occurred more frequently at bracket-adhesive interface but the failure of the ceramic bracket occurred more frequently at enamel-adhesive interface. 4.There was no statistically significant difference of the shear bond strength and adhesive failure pattern between metal bracket bonded for 2 seconds by curing with plasma arc light and 10 seconds by curing with visible light. 6.When metal brackets were bonded using plasma arc light, the shear bond strength decreased as the distance from the light source increased. The above results suggest that plasma arc light can be clinically useful for bonding the brackets without fear of the decrease of the shear bond strength.

The effect of repeated bonding on the shear bond strength of different resin cements to enamel and dentin

Ali Can Bulut,Saadet Sağlam Atsü 대한치과보철학회 2017 The Journal of Advanced Prosthodontics Vol.9 No.1

PURPOSE. Cementation failures of restorations are frequently observed in clinical practice. The purpose of this study is to compare the effect of initial and repeated bonding on the bond strengths of different resin cements to enamel and dentin. MATERIALS AND METHODS. Ninety human maxillary central incisors were bisected longitudinally. The 180 tooth halves were divided into 2 groups (n = 90) for enamel and dentin bonding. The enamel and dentin groups were further divided into 3 groups (n = 30) for different resin cement types. Composite resin (Filtek Ultimate) cylinders (3 × 3 mm) were prepared and luted to enamel and dentin using Variolink II (Group V), RelyX ARC (Group R), or Panavia F 2.0 (Group P) resin cement. After 24 hours, initial shear bond strengths of the resin cements to enamel and dentin were measured. Using new cylinders, the specimens were de-bonded and re-bonded twice to measure the first and the second bond strengths to enamel and dentin. Failure modes and bonding interfaces were examined. Data were statistically analyzed. RESULTS. Initial and repeated bond strengths to enamel were similar for all the groups. The first (15.3 ± 2.2 MPa) and second (10.4 ± 2.2 MPa) bond strengths to dentin were significantly higher in Group V (P<.0001). Second bond strengths of dentin groups were significantly lower than initial and first bond strengths to dentin (P<.0001). CONCLUSION. All resin cements have similar initial and repeated bond strengths to enamel. Variolink II has the highest first and second bond strength to dentin. Bond strength to dentin decreases after the first re-bonding for all resin cements.

The effect of repeated bonding on the shear bond strength of different resin cements to enamel and dentin

Bulut, Ali Can,Atsu, Saadet Saglam The Korean Academy of Prosthodonitics 2017 The Journal of Advanced Prosthodontics Vol.9 No.1

PURPOSE. Cementation failures of restorations are frequently observed in clinical practice. The purpose of this study is to compare the effect of initial and repeated bonding on the bond strengths of different resin cements to enamel and dentin. MATERIALS AND METHODS. Ninety human maxillary central incisors were bisected longitudinally. The 180 tooth halves were divided into 2 groups (n = 90) for enamel and dentin bonding. The enamel and dentin groups were further divided into 3 groups (n = 30) for different resin cement types. Composite resin (Filtek Ultimate) cylinders ($3{\times}3\;mm$) were prepared and luted to enamel and dentin using Variolink II (Group V), RelyX ARC (Group R), or Panavia F 2.0 (Group P) resin cement. After 24 hours, initial shear bond strengths of the resin cements to enamel and dentin were measured. Using new cylinders, the specimens were de-bonded and re-bonded twice to measure the first and the second bond strengths to enamel and dentin. Failure modes and bonding interfaces were examined. Data were statistically analyzed. RESULTS. Initial and repeated bond strengths to enamel were similar for all the groups. The first ($15.3{\pm}2.2\;MPa$) and second ($10.4{\pm}2.2\;MPa$) bond strengths to dentin were significantly higher in Group V (P<.0001). Second bond strengths of dentin groups were significantly lower than initial and first bond strengths to dentin (P<.0001). CONCLUSION. All resin cements have similar initial and repeated bond strengths to enamel. Variolink II has the highest first and second bond strength to dentin. Bond strength to dentin decreases after the first re-bonding for all resin cements.

MACRO-SHEAR BOND STRENGTH AND MICRO-SHEAR BOND STRENGTH OF CEROMER BONDED TO METAL ALLOY AND FIBER REINFORCED COMPOSITE

Park Hyung-Yoon,Cho Lee-Ra,Cho Kyung-Mo,Park Chan-Jin The Korean Academy of Prosthodonitics 2004 대한치과보철학회지 Vol.42 No.6

Statement of problem. According to the fracture pattern in several reports, fractures most frequently occur in the interface between the ceromer and the substructure. Purpose. The aim of this in vitro study was to compare the macro shear bond strength and microshear bond strength of a ceromer bonded to a fiber reinforced composite (FRC) as well as metal alloys. Material and methods. Ten of the following substructures, type II gold alloy, Co-Cr alloy, Ni-Cr alloy, and FRC (Vectris) substructures with a 12 mm in diameter, were imbedded in acrylic resin and ground with 400, and 1, 000-grit sandpaper. The metal primer and wetting agent were applied to the sandblasted bonding area of the metal specimens and the FRC specimens, respectively. The ceromer was placed onto a 6 mm diameter and 3 mm height mold in the macro-shear test and 1 mm diameter and 2 mm height mold in the micro-shear test, and then polymerized. The macro- and micro-shear bond strength were measured using a universal testing machine and a micro-shear tester, respectively. The macro- and micro-shear strength were analyzed with ANOVA and a post-hoc Scheffe adjustment ($\alpha$ = .05). The fracture surfaces of the crowns were then examined by scanning electron microscopy to determine the mode of failure. Chi-square test was used to identify the differences in the failure mode. Results. The macro-shear strength and the micro-shear strength differed significantly with the types of substructure (P<.001). Although the ceromer/FRC group showed the highest macroand micro-shear strength, the micro-shear strength was not significantly different from that of the base metal alloy groups. The base metal alloy substructure groups showed the lowest mean macro-shear strength. However, the gold alloy substructure group exhibited the least micro-shear strength. The micro-shear strength was higher than the macro-shear strength excluding the gold alloy substructure group. Adhesive failure was most frequent type of fracture in the ceromer specimens bonded to the gold alloys. Cohesive failure at the ceromer layer was more common in the base metals and FRC substructures. Conclusion. The Vectris substructure had higher shear strength than the other substructures. Although the shear strength of the ceromer bonded to the base metals was lower than that of the gold alloy, the micro-shear strength of the base metals were superior to that of the gold alloy.