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The effect of various types of mechanical and chemical preconditioning on the shear bond strength of orthodontic brackets on zirconia restorations

지르코니아 수복물과 교정용 브라켓의 전단결합강도에 대한 기계적, 화학적 전처리 방법이 미치는 영향

  • Kim, Ji Hun (김지훈, 강릉원주대학교 일반대학원)

초록/요약 도움말

The purpose of this study was to investigate the combined effect of two mechanical treatments (sandblasting by Al2O3 and CojetTM) and three chemical treatments (silane, zirconia primer, and Single Bond Universal) on the shear bond strength (SBS) of metal orthodontic brackets on zirconia restoration and to evaluate the effect of thermocycling. The zirconia specimens, prepared by 3D CAD/CAM, were randomly divided into 12 groups of 10 specimens each according to three factors: AL (Al2O3) and CO (CojetTM) by sandblasting material; SIL (silane), ZPP (Zirconia Prime Plus), and SBU (Single Bond Universal) by primer; N (not thermocycled) and T (thermocycled). The specimens were evaluated for shear bond strength between the orthodontic bracket and zirconia, and the fractured surfaces were observed using a stereomicroscope. Four additional specimens were prepared for obtaining scanning electron microscopy images. The results showed that CO-SBU combination had the highest bond strength after thermocycling (26.2 MPa). CO-SIL showed significantly higher SBS than AL-SIL (p<0.05). In addition, CO-ZPP resulted in lower bond strength than AL-ZPP before thermocycling, but the SBS of CO-ZPP increased after thermocycling (p>0.05). Fracture pattern analysis by modified Adhesive Remnant Index (ARI) scoring and SEM figures were also consistent with the results of the surface treatments. In conclusion, CO-SBU, which combines the effect of increased surface area by mechanical treatment and chemical bonding with both 10-MDP and silane, showed the highest shear bond strength. Sandblasting with either AL or CO improved the mechanical bonding by increasing the surface area, and all primer groups showed clinically acceptable increase of shear bond strength for orthodontic treatment.

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초록/요약 도움말

최근 높아진 심미수복에 대한 관심과 함께 소아청소년의 수복재료로서 지르코니아의 사용이 유치 및 초기 영구치까지 점점 증가되고 있다. 따라서 본 연구에서는 지르코니아를 대상으로 2종의 표면처리 방법과 3종의 지르코니아 전처리제의 사용에 따른 교정용 브라켓과의 접착강도를 열처리 유무에 따라 실험적으로 비교하여, 소아청소년치과의 변화하는 재료환경에 따른 최적의 치료방법을 모색하고자 하였다. 3D CAD/CAM으로 절삭가공된 지르코니아 시편들은 3가지 변수에 따라 군당 10개씩 총 12개의 군으로 무작위 할당되었다 : 1) 사용된 표면처리 재료에 따라 AL (Al2O3) 과 CO (CojetTM); 2) 지르코니아 전처리제에 따라 SIL (silane), ZPP (Zirconia Prime Plus) 와 SBU (Single Bond Universal); 3) 열처리 유무에 따라 N (not thermocycled) 과 T (thermocycled). 여러가지 기계적, 화학적 전처리 방법에 따라 지르코니아 시편들과 교정용 브라켓 사이의 전단결합강도(Shear Bond Strength)가 각각 측정되었고, 동시에 전단된 표면 양상을 광학현미경(stereomicroscope)을 통해 관찰하고, 변형된 접착제잔량지수(ARI) 측정을 통해 분석하였다. 또한 기계적 표면처리의 영향을 관찰하기 위해 주사전자현미경(Scanning Electron Microscope)을 통해 4개의 시편을 추가적으로 더 관찰하고 영상을 촬영하였다. CO-SBU 군 조합이 열처리 후에 가장 높은 전단결합강도(26.2 MPa)를 보였고, CO-SIL 군은 AL-SIL 군에 비해 유의성 있게 높은 전단결합강도를 나타냈다(p<0.05). CO-ZPP 군은 열처리전에는 AL-ZPP 군보다 낮은 결합강도를 보였으나, 열처리후에는 CO-ZPP 군의 결합력은 증가되었다(p>0.05). 변형된 접착제잔량지수 분석을 통해 얻어진 전단 양상과 주사전자현미경 관찰 모습도 표면 처리의 결과와 부합하였다. 결론적으로, 물리적 표면처리에 의해 접착 표면적이 증가되고 10-MDP 와 Silane 모두와 화학적 결합을 보인 CO-SBU 군 조합에서 가장 높은 전단결합강도가 나타났다. 그러나 표면적을 증가시키는 표면처리와 화학적 전처리의 모든 조합에서 교정 치료에 충분히 임상적으로 수용가능한 브라켓과의 결합력을 보여주었다.

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목차 도움말

Index ···········································································iii
List of figures, Tables ·······················································v
Abstract(English) ·····························································vi

I. Introduction ································································ 1
II. Materials and Methods ··················································· 4
1. Specimen preparation ··················································4
2. Group allocation and surface treatment ·····························7
1) Mechanical surface treatment through sandblasting ··········7
2) Chemical zirconia surface pretreatment························8
3. Bonding of orthodontic brackets····································10
4. Thermocycling·························································10
5. Shear bond strength measurement··································10
6. Analysis of fractured surface········································12
7. Scanning electron microscopy of zirconia surface···············12
8. Statistical analysis····················································13
Ⅲ. Results ·····································································14
1. Shear bond strength···················································14
2. Fracture pattern analysis··············································15
3. Changes after surface treatment on zirconia·······················17
Ⅳ. Discussion·································································19
Ⅴ. Conclusion ······························································· 25
Ⅵ. Reference··································································26
Ⅶ. Korean Abstract···························································28
Acknowledgement····························································30

List of Tables & Figures

Table I. Classification of experimental groups ····························7
Table II. Surface treatment product details of zirconia specimens ······8
Table III. Composition of primers applied to zirconia specimens ·······9
Table IV. Modified Adhesive Remnant Index scoring method········12
Table V. Comparison of shear bond strengths (mean ±standard deviation) ····················································14
Table VI. Modified Adhesive Remnant Index results····················15

Figure 1. Schematic diagram of experiment procedures ··················5
Figure 2. Zirconia Preparation by 3D CAD/CAM ·······················6
Figure 3. Equipment set-up for measuring shear bond strength········11
Figure 4. Stereomicroscopic Images of debonded zirconia surface····16
Figure 5. Scanning electron microscopy images of zirconia surface···18
Figure 6. Mechanical and chemical interaction model about combined effect··························································20

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