田洪琰，于 鵬，袁重陽，張 娓，仇越秀，李德慧，梁新杰，王曉燕△

(1. 北京大學(xué)口腔醫(yī)學(xué)院·口腔醫(yī)院,牙體牙髓科 口腔數(shù)字化醫(yī)療技術(shù)和材料國家工程實(shí)驗(yàn)室 口腔數(shù)字醫(yī)學(xué)北京市重點(diǎn)實(shí)驗(yàn)室，北京 100081； 2. 北京安泰生物醫(yī)用材料有限公司，北京 100094)

?

·論著·

樹脂基覆膜材料對(duì)牙根面保護(hù)作用的耐久性

田洪琰1，于 鵬1，袁重陽1，張 娓2，仇越秀2，李德慧2，梁新杰2，王曉燕1△

(1. 北京大學(xué)口腔醫(yī)學(xué)院·口腔醫(yī)院,牙體牙髓科 口腔數(shù)字化醫(yī)療技術(shù)和材料國家工程實(shí)驗(yàn)室 口腔數(shù)字醫(yī)學(xué)北京市重點(diǎn)實(shí)驗(yàn)室，北京 100081； 2. 北京安泰生物醫(yī)用材料有限公司，北京 100094)

目的：比較樹脂基覆膜材料和一步法自酸蝕粘接劑對(duì)牙根面保護(hù)作用的耐久性。方法：制備人離體后牙牙根試樣和牙本質(zhì)盤試樣，表面分別使用PRG Barrier Coat (PRG)和一步法自酸蝕粘接劑Clearfil S3Bond (CS3)處理，去離子水中靜置24 h備用。對(duì)牙根和牙本質(zhì)盤試樣分別進(jìn)行:(1)水老化及抗酸脫礦實(shí)驗(yàn)：人離體牙牙根試樣水老化處理14 d后，在脫礦緩沖液(pH 4.5)中脫礦4 d，掃描電子顯微鏡觀察橫斷面；(2)牙刷磨損實(shí)驗(yàn)：對(duì)已覆蓋PRG和CS3后的人離體后牙牙本質(zhì)盤表面進(jìn)行牙刷磨損，表面粗糙度儀測(cè)量磨損深度(Ry, μm), One-Way ANVOA法進(jìn)行統(tǒng)計(jì)分析。結(jié)果：PRG和CS3覆膜厚度分別為(47.1±27.3) μm和(5.7±2.1) μm，水老化實(shí)驗(yàn)后二者覆膜形態(tài)無明顯改變，下方牙本質(zhì)無脫礦。PRG和CS3的磨損深度隨牙刷磨損次數(shù)增加而加深，PRG組磨損深度小于CS3組(P<0.05)。結(jié)論：PRG水老化實(shí)驗(yàn)后抗酸蝕脫礦作用和CS3相似，耐牙刷磨損性能優(yōu)于CS3。

牙根齲；覆膜材料；水老化；耐磨損

隨著公眾口腔保健意識(shí)逐漸增強(qiáng)，老年人牙齒存留數(shù)目更多、時(shí)間更長,但是生理性增齡、牙周疾病以及創(chuàng)傷性刷牙習(xí)慣，導(dǎo)致齦退縮發(fā)生率上升，帶來牙本質(zhì)敏感、楔狀缺損等問題，增加了老年人剩余牙列患根面齲的風(fēng)險(xiǎn)[1]。2008年第3次全國口腔健康流行病學(xué)調(diào)查結(jié)果顯示, 我國65～74歲老年人根面齲患病率為63.6%。

利用樹脂基覆膜材料(resin-based coating material, RCM)覆蓋并預(yù)防早期根面齲，具有微創(chuàng)、高效的特點(diǎn)，逐漸受到臨床醫(yī)生的青睞。根面RCM技術(shù)發(fā)展于一步法自酸蝕粘接技術(shù)[2]，在暴露牙根表面形成薄膜物理屏障，能抵抗牙根表面酸蝕脫礦[3]，并抑制生物膜附著形成[4]，封閉牙本質(zhì)小管改善牙本質(zhì)敏感[5]。近年來，新型根面RCM中加入了氟化物成分，加強(qiáng)其防齲作用[6],另外，有研究報(bào)告一步法自酸蝕粘接劑操作簡便，與牙本質(zhì)粘接形成混合層，可抑制牙根脫礦[7]。

牙根面覆蓋保護(hù)作用與RCM材料耐久性密切相關(guān)。新型RCM與一步法自酸蝕粘接劑覆蓋根面后的耐久性尚未見報(bào)道。本研究旨在比較含表面預(yù)反應(yīng)玻璃離子填料(surface pre-reacted glass-ionomer filler，S-PRG filler)的RCM和一步法自酸蝕粘接劑的耐水老化抗脫礦及耐牙刷磨損性能，為根面防護(hù)臨床策略和新產(chǎn)品研發(fā)提供實(shí)驗(yàn)依據(jù)。

1 材料和方法

1.1 材料

選用樹脂基覆膜材料PRG Barrier Coat(PRG)和一步法自酸蝕粘接劑Clearfil S3Bond(CS3)的詳細(xì)成分及使用方法見表1。

表1 材料組成Table 1 Materials used in this study

Bis-MPEPP, 2,2-bis[(4-methacryloxy polyethoxy) phenyl] propane; Bis-GMA, bisphenol A-bisglycidyl methacrylate; HEMA, 2-hydroxyethyl methacrylate; TEGDMA, triethyleneglycol dimethacrylate; 10-MDP, 10-methacryloyloxydecyl dihydrogen phosphate; S-PRG, surface pre-reacted glass-ionomer.

1.2 覆膜材料的形態(tài)學(xué)觀察

選擇3個(gè)月內(nèi)因正畸減數(shù)拔除的前磨牙或智齒，用刮治器機(jī)械去除軟組織和根面牙骨質(zhì)，拋光后于釉牙骨質(zhì)界下0.5 mm處雙層抗酸指甲油開窗3 mm×3 mm[6]，開窗區(qū)以PRG和CS3處理，去離子水中靜置24 h后備用。PRG的使用方法：向膠囊內(nèi)滴入1滴液劑，用毛刷充分混勻10 s，涂布于牙本質(zhì)表面，靜置3 s，光照10 s。CS3的使用方法：搖勻后用小毛刷蘸滿粘接劑在牙本質(zhì)表面涂布20 s，0.1 MPa吹干10 s，光照10 s 。PRG組和CS3組各取8個(gè)樣本進(jìn)行觀察，每個(gè)樣本自開窗區(qū)中心沿預(yù)制溝劈開，掃描電子顯微鏡(scanning electron microscope,SEM)下觀察覆膜形態(tài)并測(cè)量厚度,每個(gè)樣本在中心點(diǎn)測(cè)1次，在距開窗邊緣100 μm處測(cè)2次，取均值后進(jìn)行統(tǒng)計(jì)。未使用任何材料的空白根面作為對(duì)照組(C組，圖1)。

1.3 水老化及抗酸脫礦實(shí)驗(yàn)

將1.2小節(jié)中制備的牙根樣本，根據(jù)使用材料和是否水老化(W)分為6組：空白組(對(duì)照，C-D)，空白-W組(C-W)，PRG-D組，PRG-W組，CS3-D組，CS3-W組，每組3個(gè)樣本。將C-W、PRG-W和CS3-W 3組進(jìn)行水老化處理：單個(gè)樣本分別置于含45 mL去離子水的離心管中，26 ℃，14 d，期間更換一次去離子水。然后將所有6組樣本置入10 mL pH 4.5的脫礦緩沖液[6]，每24 h更換，4 d后樣本開窗區(qū)橫斷面用S-4300/4800 SEM(日本Hitachi公司)進(jìn)行觀察。

1.4 牙刷磨損實(shí)驗(yàn)

選擇3個(gè)月內(nèi)因正畸減數(shù)拔除的前磨牙或智齒，制備1.5 mm厚牙本質(zhì)盤后拋光并沖洗[8]。根據(jù)使用材料分為空白組、PRG組和CS3組，每組再根據(jù)牙刷磨損次數(shù)分為6個(gè)組(100、200、300、500、700、1 500 次)， 共18組，每組8個(gè)樣本。將樣本置于自制牙刷磨損機(jī)內(nèi)進(jìn)行實(shí)驗(yàn)[8]，樣本表面開窗2 mm×10 mm，鋁箔保護(hù)邊緣，牙刷頭壓力300 g，頻率100 r/min，振幅30 mm，往復(fù)式磨損模式。牙刷為中等硬度刷毛(廣東三笑公司)， 磨損漿料為去離子水與牙膏(美國高露潔公司)2 g ∶1 g混合物，每組更換。牙刷磨損深度用SJ-400便攜式表面粗糙度儀(日本Mitutoyo公司)測(cè)量，記錄Ry值[9]。每個(gè)樣本測(cè)4次，取均值，使用SPSS 20.0 進(jìn)行數(shù)據(jù)統(tǒng)計(jì)，單因素方差分析(One-Way ANVOA)，檢驗(yàn)標(biāo)準(zhǔn)α=0.05；若方差齊，采用LSD法檢驗(yàn)，若方差不齊，則用Dunnett T3 法進(jìn)行檢驗(yàn)。SEM觀察磨損后樣本的表面形態(tài)。

C, control group; PRG, PRG group; CS3, CS3 group. C-1/C-2, PRG-1/PRG-2, CS3-1/CS3-2, before demineralization. 1&2 mean magnifica-tion ×1 000 and ×5 000, respectively. C-D, PRG-D, CS3-D, at pH 4.5 for 4 d (×5 000); C-W, PRG-W, CS3-W, at pH 4.5 for 4 d after 14 d water aging (×5000). D means dentin, PRG means PRG Barrier Coat, CS3 means Clearfil S Bond. Hollow arrows show demineralized dentin tubules; black arrows indicate fillers in PRG; white arrows demonstrate a thin film coating of CS3.
圖1 根面保護(hù)材料抗酸蝕脫礦的掃描電子顯微鏡觀察
Figure 1 Scanning electron microscope (SEM) of root dentin with coating materials after demineralization

2 結(jié)果

2.1 水老化后抗酸蝕脫礦作用(圖1)

空白組(C組)開窗區(qū)牙本質(zhì)脫礦凹陷，高倍鏡下牙根牙本質(zhì)小管口大部分開放，小管較細(xì)彎，管徑約為1～1.5 μm，空白組脫礦后，牙本質(zhì)小管管口擴(kuò)大，管徑增寬，管壁粗糙不平，管間牙本質(zhì)厚度變薄，C-W組與空白組相似。

PRG在牙根表面形成連續(xù)致密薄膜，厚度為(47.1±27.3) μm，與牙本質(zhì)結(jié)合緊密，界面沒有氣泡、孔隙等缺陷，PRG組即刻脫礦后覆膜與下方牙本質(zhì)形態(tài)無變化。PRG-W組水老化及脫礦后，覆膜與牙本質(zhì)結(jié)合緊密，下方牙本質(zhì)無脫礦。

CS3在牙根表面形成連續(xù)薄膜，厚度為(5.7±2.1) μm，與牙本質(zhì)結(jié)合緊密，界面無氣泡、孔隙等缺陷，CS3組即刻脫礦后覆膜與下方牙本質(zhì)形態(tài)沒有任何變化。CS3-W組水老化及脫礦后，覆膜形態(tài)無明顯變化，與牙本質(zhì)結(jié)合緊密，下方牙本質(zhì)無脫礦。

2.2 耐牙刷磨損性能

空白牙本質(zhì)、PRG和CS3的磨損深度均隨著牙刷磨損次數(shù)的增加而加深(圖2)。磨損700次以前，空白組磨損深度最小，CS3組磨損深度最大(P<0.05)；700次之后，磨損深度由大到小依次為CS3組>空白組>PRG組(P<0.01)?？瞻捉M、PRG組和CS3組磨損后的表面形態(tài)見圖3,磨損500次時(shí),空白組的磨損區(qū)表面少量不規(guī)則劃痕，PRG組的磨損區(qū)可見顯著劃痕，少量小而深的孔隙，牙本質(zhì)無暴露，CS3組的磨損區(qū)可見明顯劃痕，出現(xiàn)裂紋、碎裂和缺損，缺損處可見牙本質(zhì)暴露。磨損700次時(shí)，空白組的磨損區(qū)表面劃痕密度增加，PRG組的磨損區(qū)除劃痕外出現(xiàn)大量孔隙，表面基本完整，牙本質(zhì)無暴露,CS3組的磨損區(qū)可見大量牙本質(zhì)暴露并有劃痕存在，表面有極少的CS3殘余。磨損1 500次時(shí)，空白組的磨損區(qū)劃痕增寬連成一片，與未磨損區(qū)分界處有明顯臺(tái)階形成，PRG組的磨損區(qū)覆膜依然存在，表面出現(xiàn)裂紋、碎裂，牙本質(zhì)無暴露，CS3組的磨損區(qū)CS3完全被磨除，牙本質(zhì)完全暴露并有大量劃痕，與未磨損區(qū)分界處形成臺(tái)階。

圖2 根面保護(hù)材料的牙刷磨損深度
Figure 2 Depths of wear of coating materials by brushing cycles

3 討論

本研究結(jié)果顯示，新型RCM與自酸蝕粘接劑在牙根面形成的覆膜形態(tài)不同，這與二者成分不同密切相關(guān)。PRG提高了疏水性樹脂單體含量，并且增加了S-PRG填料顆粒，使得材料黏稠度增加。在成膜厚度上，PRG顯著厚于CS3。CS3在光固化前需要強(qiáng)氣流吹干水分和溶劑，易延展形成薄膜，但是難以保持一定的厚度。有學(xué)者提出，在實(shí)際操作中，可通過二次涂布適當(dāng)增加自酸蝕粘接劑覆膜厚度[10]。

PRG和CS3主要通過在牙本質(zhì)表面覆蓋成膜，并封閉牙本質(zhì)小管，從而隔絕外界物理、化學(xué)等有害刺激。PRG與CS3均與牙本質(zhì)結(jié)合緊密，單體滲透進(jìn)入牙本質(zhì)形成混合層，有學(xué)者研究報(bào)告這一結(jié)構(gòu)具有抗酸蝕脫礦的作用[11]。封閉膜的穩(wěn)定性是提供持久根面保護(hù)的關(guān)鍵，然而，一步法自酸蝕粘接劑中親水性單體成分含量較高，具有一定的吸水性，水可滲透并破壞粘接界面，難以維持長期抗酸蝕脫礦作用[3, 12]。本研究結(jié)果顯示，自酸蝕粘接劑CS3和新型樹脂基覆膜材料PRG水老化14 d后，抗酸脫礦能力與水老化前相似，均可以預(yù)防下方牙本質(zhì)脫礦,其長期耐水老化抗酸脫礦性能仍需進(jìn)一步研究。

a, control group (dentin); b, PRG group, c, CS3 group. a1, b1, c1, after 500 cycles of brush; a2, b2, c2, after 700 cycles; a3, b3, c3, after 1 500 cycles. N, non-brush area; A, toothbrush abrasion area. White arrows show the strokes of toothbrush wear; black hollow arrows show the pits on PRG surface; white hollow arrows show residual CS3 on dentin surface; black arrows indicate the cracks and defects of materials, and triangle, the visible uncoated dentin.

圖3 根面保護(hù)材料牙刷磨損后的表面形態(tài)SEM觀察
Figure 3 SEM of the dentin with coating materials after toothbrush abrasion

樹脂基覆膜材料加入填料和功能性單體，除了增加成膜厚度，還提高了覆膜的耐牙刷磨損性能，延長了覆膜材料的根面保護(hù)作用壽命。Gando等[13]報(bào)道，樹脂基覆膜材料添加了3D-SR單體和玻璃離子填料，可經(jīng)受50 000次牙刷磨損，抗磨損性能顯著提高。在臨床實(shí)際情況中，牙列一年所受到牙刷磨損約為10 000次[14-15]。本研究觀察到PRG的耐磨性優(yōu)于CS3，根據(jù)磨損曲線推算，當(dāng)前實(shí)驗(yàn)條件下PRG可經(jīng)受12 500次以上牙刷磨損，相當(dāng)于臨床條件下1年以上磨損量的水平。本研究還顯示，PRG和CS3的磨損模式不同，掃描電鏡下體現(xiàn)不同的表面形態(tài)?？偟膩碇v，CS3本身填料少，樹脂基質(zhì)強(qiáng)度不如牙本質(zhì)，所以磨損深度最大；700次磨損之后CS3幾乎完全磨除，磨損表面形態(tài)與空白組類似。PRG在700次磨損之前，接受磨損的部分主要為較軟的樹脂基質(zhì)部分，前期磨損模式與CS3類似；在700次之后，PRG基質(zhì)磨除一層后暴露硬度高的S-PRG填料顆粒，高出周圍基質(zhì)的填料顆粒受磨損作用從材料表面脫出而形成大量孔隙，但覆膜整體磨損速率減慢了，因此PRG磨損深度顯著小于CS3和牙本質(zhì)，掃描電鏡表面形態(tài)觀察也符合這一點(diǎn)。PRG中的S-PRG填料還能釋放氟、鍶、硼、鈉等離子，兼具氟釋放及再補(bǔ)充氟的功能，并能減少生物膜黏附[16-18]。有研究證明，PRG能抑制釉質(zhì)齲進(jìn)展，并有較好的長期抗牙本質(zhì)齲效果[19-21]。

綜上所述，樹脂基覆膜材料PRG Barrier Coat對(duì)牙根面的保護(hù)作用具有一定的耐久性，能為暴露根面提供一定防護(hù)作用，其實(shí)際臨床應(yīng)用效果需要進(jìn)一步研究。

[1]Imazato S, Ikebe K, Nokubi T, et al. Prevalence of root caries in a selected population of older adults in Japan[J]. J Oral Rehabil, 2006, 33(2): 137-143.

[2]Takahashi R, Nikaido T, Ariyoshi M, et al. Microtensile bond strengths of a dual-cure resin cement to dentin resin-coated with an all-in-one adhesive system using two curing modes[J]. Dent Mater J, 2010, 29(3): 268-276.

[3]Kaneshiro AV, Imazato S, Ebisu S, et al. Effects of a self-etching resin coating system to prevent demineralization of root surfaces[J]. Dent Mater, 2008, 24(10): 1420-1427.

[4]Daneshmehr L, Matin K, Nikaido T, et al. Effects of root dentin surface coating with all-in-one adhesive materials on biofilm adherence[J]. J Dent, 2008, 36(1): 33-41.

[5]Yu X, Liang B, Jin X, et al. Comparativeinvivostudy on the desensitizing efficacy of dentin desensitizers and one-bottle self-etching adhesives[J]. Oper Dent, 2010, 35(3): 279-286.

[6]Ma S, Imazato S, Chen JH, et al. Effects of a coating resin containing S-PRG filler to prevent demineralization of root surfaces[J]. Dent Mater J, 2012, 31(6): 909-915.

[7]Tajima K, Nikaido T, Inoue G, et al. Effects of coating root dentin surfaces with adhesive materials [J]. Dent Mater J, 2009, 28(5): 578-586.

[8]Parry J, Harrington E, Rees G D, et al. Control of brushing variables for the in vitro assessment of toothpaste abrasivity using a novel laboratory model[J]. J Dent, 2008, 36(2): 117-124.

[9]Wiegand A, Burkhard J P, Eggmann F, et al. Brushing force of manual and sonic toothbrushes affects dental hard tissue abrasion[J]. Clin Oral Investig, 2013, 17(3): 815-822.

[10]Takahashi R, Nikaido T, Ariyoshi M, et al. Thin resin coating by dual-application of all-in-one adhesives improves dentin bond strength of resin cements for indirect restorations[J]. Dent Mater J, 2010, 29(5): 615-622.

[11]Nurrohman H, Nikaido T, Takagaki T, et al. Dentin bonding performance and ability of four MMA-based adhesive resins to prevent demineralization along the hybrid layer[J]. J Adhes Dent, 2012, 14(4): 339-348.

[12]Sauro S, Watson TF, Tay FR, et al. Water uptake of bonding systems applied on root dentin surfaces: a SEM and confocal microscopic study[J]. Dent Mater, 2006, 22(7): 671-680.

[13]Gando I, Ariyoshi M, Ikeda M, et al. Resistance of dentin coating materials against abrasion by toothbrush [J]. Dent Mater J, 2013, 32(1): 68-74.

[14]Korbmacher-Steiner HM, Schilling AF, Huck LG, et al. Laboratory evaluation of toothbrush/toothpaste abrasion resistance after smooth enamel surface sealing[J]. Clin Oral Investig, 2013, 17(3): 765-774.

[15]Winterfeld T, Schlueter N, Harnacke D, et al. Toothbrushing and flossing behaviour in young adults： a video observation[J]. Clin Oral Investig, 2014, 19(4): 1-8.

[16]Murayama R, Furuichi T, Yokokawa M, et al. Ultrasonic investigation of the effect of S-PRG filler-containing coating material on bovine tooth demineralization [J]. Dent Mater J, 2012, 31(6): 954-959.

[17]Shimazu K, Ogata K, Karibe H. Evaluation of the ion-releasing and recharging abilities of a resin-based fissure sealant containing S-PRG filler[J]. Dent Mater J, 2011, 30(6): 923-927.

[18]Suzuki N, Yoneda M, Haruna K, et al. Effects of S-PRG eluate on oral biofilm and oral malodor [J]. Arch Oral Biol, 2014, 59(4): 407-413.

[19]Hosoya Y, Ando S, Otani H, et al. Ability of barrier coat S-PRG coating to arrest artificial enamel lesions in primary teeth[J]. Am J Dent, 2013, 26(5): 286-290.

[20]Kotaku M, Murayama R, Shimamura Y, et al. Evaluation of the effects of fluoride-releasing varnish on dentin demineralization using optical coherence tomography[J]. Dent Mater J, 2014, 33(5): 648-655.

[21]Kaga M, Kakuda S, Ida Y, et al. Inhibition of enamel deminera-lization by buffering effect of S-PRG filler-containing dental sealant[J]. Eur J Oral Sci, 2014, 122(1): 78-83.

(2015-04-25收稿)

(本文編輯：王 蕾)

Durability of protective effect of resin-based coating material on root surface

TIAN Hong-yan1, YU Peng1, YUAN Chong-yang1, ZHANG Wei2, QIU Yue-xiu2, LI De-hui2, LIANG Xin-jie2, WANG Xiao-yan1△

(1. Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing 100081, China；2. AT&M Biomaterial Co., Ltd， Beijing 100094, China)

Objective： To compare the durability of resin-based root-surface coating material and all-in-one self-etching adhesive on root surfaceinvitro. Methods: Human extracted premolars or molars with intact roots were selected. The cementum was removed using a periodontal scaler to expose root dentin.The root surface was coated with an acid-resistant nail varnish, leaving a window of 3 mm×3 mm on the exposed dentin.The window was covered with either PRG Barrier Coat (PRG) or Clearfil S3Bond (CS3). After water aging for 14 d, specimens were immersed in acid buffer at pH 4.5 for 4 d and the demineralization buffer was changed every 24 h. Then the specimen was split longitudinally through the center of the ‘window’ and the cross-sectional surface was observed with scanning electron microscope (SEM). After fixed and dehydrated, the prepared samples were coated with platinum. The coating material, root dentin and the interface was observed by scanning electron microscope (SEM). The thickness of the coating material was measured on the SEM images. Regarding toothbrush wear test, coronal dentindisks were prepared and covered with PRG and CS3, respectively. After storage in water for 24 h, the specimen was subjected to the toothbrush wear tester for 100, 200, 300, 500, 700, 1 500 brushing cycles. A slurry of fluoride toothpaste (1 ∶2 ratio of toothpaste and deionized water by weight) was used and the brushing load was 300 N. The surface microstructure of remaining coating material was analyzed using SEM. The wear depths were determined by a profilometer. Statistical analysis was performed with SPSS 20.0 by one-way ANOVA. The level of significance was at 0.05. Results: Application of PRG Barrier Coat produced a coating layer of (47.1±27.3) μm, while CS3 presented a thin film of (5.7±2.1) μm in thickness. The exposed dentin was hermetically sealed and no obvious gap was observed at the interface in both PRG and CS3 groups. There was no dentin demineralization observed in both groups after water aging. The wear depths of PRG and CS3 increased along with the numbers of brushing cycles. PRG wore at a significant lower pace than CS3 did (P<0.05). Conclusion: PRG coating resin had similar performances as CS3 on protecting root dentin from demineralization after water aging. What’s more, PRG demonstrated a higher toothbrush wear resistance than CS3. We concluded that PRG Barrier Coat contained S-PRG filler may be an effective coating material for protecting exposed root from both chemical and mechanical challenges. Further studies should be carried out to evaluate the long-term reliability of the rootsurface coating materials under the clinical setting.

Root caries; Coating material; Water aging; Wear resistance

北京市科學(xué)技術(shù)委員會(huì)計(jì)劃項(xiàng)目(Z14110000514016)資助Supported by Beijing Municipal Science & Technology Commission Project (Z14110000514016)

時(shí)間：2016-9-5 15：56：36

http://www.cnki.net/kcms/detail/11.4691.R.20160905.1556.048.html

R781.33

A

1671-167X(2016)05-0889-05

10.3969/j.issn.1671-167X.2016.05.026

△ Corresponding author’s email, wangxiaoyan@pkuss.bjmu.edu.cn