革命性口腔保健:使用唾液快速檢測牙周病的前景

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牙周病是一種由細菌感染引起的慢性牙齦炎症,可能導致連接組織和骨骼破壞。韓國的研究者提出,利用唾液進行現場診斷牙周病的技術已逐漸可行,這將為早期診斷和治療開啟新的可能性。儘管目前還面臨一些驗證挑戰,但已確認多個有希望的唾液生物標記物,這些發現為未來牙科診斷提供了新的途徑。

Suk Ji1 Youngnim Choi2*
1Department of Periodontology, Anam Hospital, Korea University, Seoul, South Korea
2Department of Oral Microbiology and Immunology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, South Korea

Front. Cell. Infect. Microbiol., 03 September 2015
Sec. Molecular Bacterial Pathogenesis
Volume 5 – 2015 |

https://doi.org/10.3389/fcimb.2015.00065

牙周炎是由持續的細菌感染引起的牙周組織的慢性炎症,導致結締組織和骨骼的破壞。由於齒槽骨損失後牙周組織的重建能力有限,早期診斷和干預應該是牙周治療的首要目標。然而,牙周炎經常在沒有明顯症狀的情況下進展,許多患者在牙周破壞進展到無法挽回的地步之前不會尋求專業牙科護理。此外,當前對牙周炎的診斷依賴於耗時的臨床測量。因此,對於牙周炎的近患者測試存在未滿足的需求。唾液作為牙周炎的近患者診斷工具是一種理想的生物流體。近期在點護理(POC)測試方面的發展表明,現在技術上已經可行使用唾液進行牙周炎的診斷測試。已報告了多個與牙周炎相關的有前途的唾液生物標誌物。必須根據牙周炎的發病機制仔細選擇最佳生物標誌物組合。使用唾液進行牙周炎POC診斷的最大障礙可能是在大型、多樣化的患者群體中進行驗證的過程。因此,我們提議成立國際牙周病生物標誌物聯盟,集結努力識別、選擇和驗證用於牙周炎診斷的唾液生物標誌物。

唾液診斷牙周病的用途

牙周病是由持續的細菌感染引起的牙周組織的慢性炎症,導致結締組織和骨骼破壞(Ji et al., 2014)。由於其慢性特性,牙周病進展時不會在口腔中造成嚴重不適,患者通常只有在牙周組織被大量破壞後才尋求專業護理。因此,需要使用一種簡便、安全且容易獲得的方法在初期階段診斷牙周病。牙周病目前是通過X光攝影和臨床測量探針口袋深度(PD)、探針出血(BOP)和臨床附著水平(CAL)來診斷的(Salvi et al., 2008)。然而,這些傳統的臨床測量耗時且提供的信息有限,因為它們是以前牙周病的指標,而非當前病情活動的指標。此外,它們不足以預測未來可能面臨牙周病風險的易感個體。到目前為止,最好的牙齦炎症預測指標是BOP,但這種方法存在太多假陽性(Lang et al., 1990)。目前迫切需要近患者測試來診斷牙周病。

唾液是作為牙周病診斷工具的理想生物流體。唾液的收集安全、非侵入性且簡單,且可多次收集唾液,對患者的不適感最小。已經在唾液中鑒定出多個與牙周病臨床參數相關的有希望的生物標誌物(Miller et al., 2010; AlMoharib et al., 2014; Taylor, 2014)。唾液包含由宿主和細菌產生的局部蛋白質、遺傳/基因組生物標誌物如DNA和mRNA,以及各種代謝物(Cuevas-Córdoba and Santiago-García, 2014)。然而,使用唾液診斷牙周病在檢測每個單獨牙齒部位的病情活動上有限制;需要傳統的臨床測量來實現這一點。在這方面,使用唾液診斷牙周病必須實現為點護理(POC)測試。POC測試被定義為在實驗室外或患者護理現場附近進行的醫學測試,包括患者的床邊、醫生的辦公室和患者的家(Song et al., 2014)。如果使用唾液的POC設備診斷牙周病,患者可以輕鬆地在家自我診斷牙周病,並在合適的時間前往牙科診所。在牙科診所,可以輕鬆地在椅邊監控當前病情活動和治療反應。一個用於診斷牙周病的POC設備也可以幫助醫生評估患者的牙周狀態,因為牙周病與許多全身疾病有關,如動脈粥樣硬化、冠心病、糖尿病和類風濕性關節炎(Scannapieco, 2005; Kobayashi and Yoshie, 2015)。當醫生開處方雙膦酸鹽或其他與藥物相關的頜骨壞死(MRONJ)相關的藥物時,他們可以事先考慮患者的牙周狀態,以防止MRONJ的發展,這是與拔牙結合的藥物使用常見的併發症(Katsarelis et al., 2015)。近期POC測試的發展表明,現在技術上已經可行使用唾液診斷牙周病。

唾液診斷在牙周病的應用價值

牙周炎是由持續性細菌感染引起的牙周組織慢性炎症,導致結締組織和骨骼的破壞(Ji等人,2014)。由於其慢性特性,牙周炎在不引起口腔嚴重不適的情況下進展,患者通常只有在牙周組織遭到相當破壞後才尋求專業護理。因此,有必要使用一種簡單、安全且易於獲取的方法在其初期診斷牙周炎。目前牙周炎的診斷是使用放射線學和牙周袋探測深度(PD)、探測出血(BOP)和臨床附著水平(CAL)等臨床測量(Salvi等人,2008)。然而,這些傳統的臨床測量耗時且提供的信息有限,因為它們是早前牙周疾病而不是現在疾病活動的指標。此外,它們無法預測未來可能患牙周炎的易感個體。迄今為止,牙齦炎症的最佳預測因子是BOP,但與此方法相關的偽陽性太多(Lang等人,1990)。診斷牙周炎的近端檢測需求尚未得到滿足。

唾液是作為牙周炎診斷工具的理想生物液體。唾液的收集安全、無侵入性且簡單,並且可以重複收集,對患者造成最小的不適。唾液中已經識別出許多與牙周炎臨床參數相關的有前景的生物標記物(Miller等人,2010;AlMoharib等人,2014;Taylor,2014)。唾液包含局部產生的蛋白質、基因/基因組標記物如DNA和mRNA,以及源自宿主和細菌的各種代謝物(Cuevas-Córdoba和Santiago-García,2014)。然而,使用唾液診斷牙周炎在每個個齒位檢測疾病活動存在限制;為了完成這一點,需要傳統的臨床測量。在這方面,使用唾液診斷牙周炎必須實現為即時檢測。即時檢測是指在患者護理現場之外進行的醫療檢測,包括患者的病床邊、醫生辦公室和患者的家中(Song等人,2014)。如果使用唾液進行即時診斷牙周炎的即時檢測設備,患者可以輕鬆在家中診斷自己的牙周炎,並在適當的時間訪問牙科診所。在牙科診所,可以輕鬆地在椅邊監測當前疾病活動和對治療的反應。診斷牙周炎的即時檢測設備還將幫助醫生評估其患者的牙周狀況,因為牙周炎與許多全身性疾病(如動脈粥樣硬化、冠心病、糖尿病和風濕性關節炎)有關(Scannapieco,2005;Kobayashi和Yoshie,2015)。當醫生處方磷酸鹽類或其他與口服抗生素相關的藥物時,他們可以事先考慮患者的牙周狀況,以防止發展MRONJ,這是與拔牙相結合的常見併發症(Katsarelis等人,2015)。近期的即時檢測發展表明,使用唾液診斷牙周炎現在在技術上是可行的。

分子診斷的即時檢測技術

在生物流體中檢測生物標記信號的技術已經取得了顯著進展。特別是微流體和芯片實驗室技術的結合使得可以在即時檢測點(POC)的小體積生物液體中實時監測生物標記物(Sackmann等人,2014)。芯片實驗室方法將採樣、樣品準備、檢測和數據分析等處理步驟集成到一個小型設備中(Su等人,2015)。基於微流體的設備可以分析各種臨床樣本,包括血液、唾液、鼻液和尿液(Su等人,2015)。

POC技術檢測到的診斷目標包括核酸、蛋白質、代謝物和其他小分子(Song等人,2014;Su等人,2015)。例如,核酸可以通過芯片上的PCR(非等溫)或芯片上的等溫擴增技術進行增殖(Su等人,2015)。許多基於PCR的POC設備已經商業化,用於檢測諸如流感、RSV、HIV、耐甲氧西林金黃色葡萄球菌、難辨梭菌和瘧疾等病原體(Su等人,2015)。POC DNA測試也已經開發出來,用於檢測與各種癌症相關的基因突變(Yang等人,2014)。對蛋白質生物標記物的微流體檢測通常依賴於基於抗體的免疫分析。用於與高特異性和敏感性結合的各種生物分子的aptamer、DNA或RNA寡核苷酸是抗體的替代品(Toh等人,2015)。簡單的側向流動分析法快速且特異性高,但不敏感或定量。已經開發出多種新技術,以提高敏感性並允許多重蛋白質生物標記物的定量測量(Gaster等人,2009;Warsinke,2009;Rissin等人,2010;de la Rica和Stevens,2012)。葡萄糖是POC測試的最知名代謝物,已有很長的使用歷史(Wilkins和Atanasov,1996)。現在,可以使用POC技術定量測量更廣泛範圍的分析物(Sia和Chin,2011)。例如,i-STAT POC設備,每年銷售數百萬個,可以電化學地測量血氣(pH、PCO2、PO2、TCO2、HCO3、鹼過量和sO2)、電解質(鈉、鉀、氯、TCO2、陰離子間隙、游離鈣、葡萄糖、尿素氮、肌酐和乳酸)和血液學(紅細胞比容和血紅蛋白)參數(Lauks,1998)。還開發出了一種測量一氧化氮的微流體設備(Halpin和Spence,2010)。

已經開發出各種各樣的方法來檢測目標分子,但光學檢測和電化學檢測是最常採用的方法。POC設備中實施的光學檢測方法包括吸收比色法、化學發光法、螢光法、表面增強拉曼散射光譜法和表面電漿共振(Gubala等人,2012;Su等人,2015)。電化學檢測方法包括安培計、電位計和阻抗計測量(Su等人,2015)。

牙周炎的唾液生物標記物

理想的牙周炎生物標記物必須能夠(1)診斷牙周疾病的存在,(2)反映疾病的嚴重程度,(3)監測疾病對治療的反應,以及(4)預測疾病的預後/進展。已經在唾液中確定了滿足至少其中一項四個要求的多個生物標記物(表1-4)。牙周病的唾液生物標記物可以來自細菌和宿主。隨著牙周炎的進展,牙齦炎症、軟組織破壞和骨破壞依次發生,並釋放相關的蛋白質或代謝物進入唾液。因此,基於宿主的生物標記物根據它們是否反映炎症、軟組織破壞或骨破壞進行分類。在至少三個獨立研究中滿足四個要求中的三個的生物標記物被歸類為強(S)生物標記物。當報告沒有差異或矛盾結果的研究數量等於或大於支持性結果的研究數量時,生物標記物被歸類為可疑(Q)。其餘的生物標記物被歸類為潛在(P)。

表1. 來自細菌的唾液生物標記物

來自細菌的生物標記物

來自細菌的生物標記物包括DNA和蛋白質。通過針對16S rRNA基因的特定區域,確定了唾液中著名的致病性細菌水平,例如黏聚體原生體組織培養劑,三種紅色複合物種,以及幾種橙色複合物的物種(見表1)。其中,只有細菌物種Porphyromonas gingivalis,Prevotella intermedia和Tannerella forsythia已被多項研究證明為牙周炎的強生物標記物。最近使用16S rRNA基因的高通量測序識別了與牙周炎相關的新物種/類型(Griffen等人,2012;Göhler等人,2014)。鑒於牙齲生物膜的複雜性,需要研究新識別的物種/類型作為牙周炎唾液生物標記物的潛力。已證實唾液中二肽二肽酶IV的活性與牙周炎和P. gingivalis的存在有關(Aemaimanan等人,2009)。二肽二肽酶IV是一種丝氨酸蛋白酶,它從多肽鏈的N-末端剪切X-Pro二肽,從而促進膠原蛋白的降解(Banbula等人,2000)。唾液中的DPP4可能來自宿主和細菌,包括P. gingivalis(Aemaimanan等人,2009)。

宿主源性炎症生物標記物

牙周炎始於牙齲生物膜引起的牙齦組織炎症。作為唾液中的炎症生物標記物,已經研究了各種酶(精胺酶、二肽二肽酶IV、β-葡萄糖苷酶和髓過氧化物酶)、抗微生物蛋白質(乳鐵蛋白和鈣蛋白)、炎症細胞因子(IL-1β、IL-6、IL-18、IFN-γ和MIP-1α)和介導炎症的蛋白質(化學物質、CRP、TLR4、可溶性CD14和降鈣素)(見表2)。特別是IL-1β、MIP-1α和精胺酶是與牙周炎炎症參數(如牙齦指數或探測出血)相關的強生物標記物(Miller等人,2006;Gheren等人,2008;Al-Sabbagh等人,2012;Rathnayake等人,2013)。除了蛋白質生物標記物外,一氧化氮、8-羥基脫氧鳥苷、血小板活化因子和脂肪酸代謝物(新研究、十二烯酸、亞麻油酸和花生四烯酸)也被識別為唾液中與炎症相關的生物標記物(見表2)。

表2. 與炎症相關的宿主源性唾液生物標記物

與軟組織破壞相關的宿主源性生物標記物

隨著牙周炎的進展,軟組織被破壞,釋放出參與組織破壞的多種酶和蛋白質進入唾液。其中,MMP-8、MMP-9、HGF、乳酸脫氫酶、天冬氨酸氨基轉移酶和TIMP-2是牙周炎的強生物標記物或潛在生物標記物(見表3)。此外,最近對唾液進行的代謝物組學分析顯示,在牙周炎中,源自大分子降解的代謝物量增加,包括二肽(蛋白質)、低聚/單醣(多糖)、溶脂質、脂肪酸和單酰甘油(甘油磷脂和三酰甘油),以及尿苷(DNA/RNA)(見表3)。

表3. 與軟組織破壞相關的宿主源性唾液生物標記物

與骨破壞相關的宿主源性生物標記物

在牙周炎中,唾液骨重塑的生物標記物可以用作骨破壞的指標。這些包括鹼性磷酸酶、骨連結蛋白、RANKL和鈣(見表4)。已報告唾液鈣水平與CAL水平呈正相關(Sutej等人,2012)。

表4. 與硬組織破壞相關的宿主源性唾液生物標記物

進一步考慮

在列出的各種唾液生物標記物中,至少有一項研究表明,P. gingivalis已滿足牙周炎理想生物標記物的所有四項要求。然而,單一生物標記物的檢測可能沒有足夠的效力進行準確的診斷,因為可能存在假陽性或假陰性結果。牙周炎是一種涉及細菌與宿主免疫系統之間複雜相互作用的疾病。結合宿主源性生物標記物(反映炎症、軟組織破壞和骨破壞)以及細菌源性生物標記物可能有助於診斷牙周炎的存在,以及疾病的進展程度和對治療的反應。許多宿主源性生物標記物已經顯示出與牙周炎的強烈相關性。

生物標記物的濃度可能受到唾液流速、昼夜節律、年齡、患者的生理狀態和其他因素的影響,這引起了使用唾液生物標記物進行診斷的準確性和可重復性的擔憂(Nový,2014)。雖然一些唾液蛋白質的非刺激和刺激樣本之間以及隨時間的相關性已經報告(Rudney等人,1985),但並未對所有唾液蛋白質組或代謝物組進行這樣的研究。儘管如此,許多生物標記物在眾多研究中已經顯示出與牙周炎的一致相關性。例如,在使用非刺激全口唾液樣本的六項研究中觀察到牙周炎中唾液中MMP-8的水平顯著高於健康對照組(Miller等人,2006;Christodoulides等人,2007;Ramseier等人,2009;Costa等人,2010;Mirrielees等人,2010;Ebersole等人,2013),在使用刺激全口唾液樣本的五項研究中也觀察到相同的現象(Gorska和Nedzi-Gora,2006;Gursoy等人,2010,2013;Meschiari等人,2013;Rathnayake等人,2013)。這些研究結果表明,如果選擇具有顯著組間差異的生物標記物,則可以克服唾液生物標記物濃度的受試者內變異,以進行診斷目的。

在牙周病學中的POC設備

一些POC設備已經開發用於牙周炎的唾液診斷。一種名為“集成微流控口腔診斷平台(IMPOD)”的設備能夠通過將樣品預處理(過濾、濃縮、混合)與電泳免疫分析和激光誘導螢光檢測系統集成,以檢測低樣品體積要求(10微升)和相當靈敏度(nM-pM)的唾液蛋白。使用該設備,可以在唾液中迅速(<10分鐘)測量MMP-8、TNF-α、IL-6和CRP(Herr等人,2007a,b)。然而,其在臨床環境中的驗證尚未報告。

德克薩斯大學奧斯汀分校的一個小組開發了一種將微流體學和基於螢光的光學系統集成的LOC系統,其中在化學敏感的珠子上進行夾心免疫分析。他們報告了LOC系統應用於多重測量三種唾液生物標記物:C-反應蛋白、MMP-8和IL-1β,這些生物標記物與牙周炎的臨床表現有關。LOC方法的檢測極限比標準ELISA低了五個量級,且LOC方法得到的結果與ELISA結果一致(Christodoulides等人,2007)。目前正在臨床試驗中研究使用此LOC方法的POC設備是否能夠準確測量唾液生物標記物MMP-8的水平,並因此指示患者是否牙周健康、牙齦炎或牙周疾病(在ClinicalTrials.gov的NCT02403297)。

建議組織國際牙周病唾液生物標記聯盟

為了成功地使用唾液進行牙周炎的 POC 诊断,重要的是要用大型人群对候选生物标记进行验证,这些人群要合适地考虑到种族、地区、性别和年龄等因素。在牙周研究中,全口或选定的牙齿已被检查以诊断牙周炎,并且不同的标准也被用来分类牙周炎的严重程度。患者分类的这种差异使得很难整合不同研究的结果。此外,唾液采样方法的变化(例如,静息 vs. 刺激、整体 vs. 单个腺体采样)、靶生物标记以及唾液生物标记的检测方法阻止了从不同研究或中心获取的数据的直接比较。我们提议组织一个国际牙周病唾液生物标记联盟(ICSBP)。ICSBP 可以提出协作努力,制定临床研究的标准化方案,包括牙周炎的临床诊断的统一方法。此外,ICSBP 可以通过共享临床样本和经验来加速生物标记的验证和唾液诊断的实施。

參考文獻

Acharya, A., Kharadi, M. D., Dhavale, R., Deshmukh, V. L., and Sontakke, A. N. (2011). High salivary calcium level associated with periodontal disease in Indian subjects–a pilot study. Oral Health Prev. Dent. 9, 195–200.

PubMed Abstract | Google Scholar

Aemaimanan, P., Sattayasai, N., Wara-aswapati, N., Pitiphat, W., Suwannarong, W., Prajaneh, S., et al. (2009). Alanine aminopeptidase and dipeptidyl peptidase IV in saliva of chronic periodontitis patients. J. Periodontol. 80, 1809–1814. doi: 10.1902/jop.2009.090233

PubMed Abstract | CrossRef Full Text | Google Scholar

AlMoharib, H. S., AlMubarak, A., AlRowis, R., Geevarghese, A., Preethanath, R. S., and Anil, S. (2014). Oral fluid based biomarkers in periodontal disease: part 1. Saliva. J. Int. Oral Health 6, 95–103.

PubMed Abstract | Google Scholar

Al-Sabbagh, M., Alladah, A., Lin, Y., Kryscio, R. J., Thomas, M. V., Ebersole, J. L., et al. (2012). Bone remodeling-associated salivary biomarker MIP-1α distinguishes periodontal disease from health. J. Periodontal Res. 47, 389–395. doi: 10.1111/j.1600-0765.2011.01445.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Aurer, A., Jorgic-Srdjak, K., Plancak, D., Stavljenic-Rukavina, A., and Aurer-Kozelj, J. (2005). Proinflammatory factors in saliva as possible markers for periodontal disease. Coll. Antropol. 29, 435–439.

PubMed Abstract | Google Scholar

Banbula, A., Bugno, M., Goldstein, J., Yen, J., Nelson, D., Travis, J., et al. (2000). Emerging family of proline-specific peptidases of Porphyromonas gingivalis: purification and characterization of serine dipeptidyl peptidase, a structural and functional homologue of mammalian prolyl dipeptidyl peptidase IV. Infect. Immun. 68, 1176–1182. doi: 10.1128/IAI.68.3.1176-1182.2000

PubMed Abstract | CrossRef Full Text | Google Scholar

Banu, S., Jabir, N. R., Mohan, R., Manjunath, N. C., Kamal, M. A., Kumar, K. R., et al. (2015). Correlation of Toll-like receptor 4, interleukin-18, transaminases, and uric acid in patients with chronic periodontitis and healthy adults. J. Periodontol. 86, 431–439. doi: 10.1902/jop.2014.140414

PubMed Abstract | CrossRef Full Text | Google Scholar

Barnes, V. M., Ciancio, S. G., Shibly, O., Xu, T., Devizio, W., Trivedi, H. M., et al. (2011). Metabolomics reveals elevated macromolecular degradation in periodontal disease. J. Dent. Res. 90, 1293–1297. doi: 10.1177/0022034511416240

PubMed Abstract | CrossRef Full Text | Google Scholar

Barnes, V. M., Kennedy, A. D., Panagakos, F., Devizio, W., Trivedi, H. M., Jönsson, T., et al. (2014). Global metabolomic analysis of human saliva and plasma from healthy and diabetic subjects, with and without periodontal disease. PLoS ONE 18:e105181. doi: 10.1371/journal.pone.0105181

PubMed Abstract | CrossRef Full Text | Google Scholar

Buduneli, N., Biyikoglu, B., Sherrabeh, S., and Lappin, D. F. (2008). Saliva concentrations of RANKL and osteoprotegerin in smoker versus non-smoker chronic periodontitis patients. J. Clin. Periodontol. 35, 846–852. doi: 10.1111/j.1600-051X.2008.01310.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Canakçi, C. F., Canakçi, V., Tatar, A., Eltas, A., Sezer, U., Ciçek, Y., et al. (2009a). Increased salivary level of 8-hydroxydeoxyguanosine is a marker of premature oxidative mitochondrial DNA damage in gingival tissue of patients with periodontitis. Arch. Immunol. Ther. Exp. 57, 205–211. doi: 10.1007/s00005-009-0026-9

PubMed Abstract | CrossRef Full Text | Google Scholar

Canakçi, C. F., Cicek, Y., Yildirim, A., Sezer, U., and Canakci, V. (2009b). Increased levels of 8-hydroxydeoxyguanosine and malondialdehyde and its relationship with antioxidant enzymes in saliva of periodontitis patients. Eur. J. Dent. 3, 100–106.

PubMed Abstract | Google Scholar

Christodoulides, N., Floriano, P. N., Miller, C. S., Ebersole, J. L., Mohanty, S., Dharshan, P., et al. (2007). Lab-on-a-chip methods for point-of-care measurements of salivary biomarkers of periodontitis. Ann. N. Y. Acad. Sci. 1098, 411–428. doi: 10.1196/annals.1384.035

PubMed Abstract | CrossRef Full Text | Google Scholar

Costa, P. P., Trevisan, G. L., Macedo, G. O., Palioto, D. B., Souza, S. L., Grisi, M. F., et al. (2010). Salivary interleukin-6, matrix metalloproteinase-8, and osteoprotegerin in patients with periodontitis and diabetes. J. Periodontol. 81, 384–391. doi: 10.1902/jop.2009.090510

PubMed Abstract | CrossRef Full Text | Google Scholar

Cuevas-Córdoba, B., and Santiago-García, J. (2014). Saliva: a fluid of study for OMICS. OMICS 18, 87–97. doi: 10.1089/omi.2013.0064

PubMed Abstract | CrossRef Full Text | Google Scholar

Dabra, S., and Singh, P. (2012). Evaluating the levels of salivary alkaline and acid phosphatase activities as biochemical markers for periodontal disease: a case series. Dent. Res. J. 9, 41–45. doi: 10.4103/1735-3327.92942

PubMed Abstract | CrossRef Full Text | Google Scholar

de la Peña, V. A., Dios, P. D., Rodríguez-Nuñez, I., and Rodríguez-Segade, S. (2005). Effect of ultrasonic scaling on salivary lactate dehydrogenase. Am. J. Dent. 18, 113–115.

PubMed Abstract | Google Scholar

de la Rica, R., and Stevens, M. M. (2012). Plasmonic ELISA for the ultrasensitive detection of disease biomarkers with the naked eye. Nat. Nanotechnol. 7, 821–824. doi: 10.1038/nnano.2012

PubMed Abstract | CrossRef Full Text | Google Scholar

Ebersole, J. L., Schuster, J. L., Stevens, J., Dawson, D. III. Kryscio, R. J., Lin, Y., et al. (2013). Patterns of salivary analytes provide diagnostic capacity for distinguishing chronic adult periodontitis from health. J. Clin. Immunol. 33, 271–279. doi: 10.1007/s10875-012-9771-3

PubMed Abstract | CrossRef Full Text | Google Scholar

Fine, D. H., Furgang, D., and Beydouin, F. (2002). Lactoferrin iron levels are reduced in saliva of patients with localized aggressive periodontitis. J. Periodontol. 73, 624–630. doi: 10.1902/jop.2002.73.6.624

PubMed Abstract | CrossRef Full Text | Google Scholar

Fine, D. H., Markowitz, K., Fairlie, K., Tischio-Bereski, D., Ferrandiz, J., Godboley, D., et al. (2014). Macrophage inflammatory protein-1α shows predictive value as a risk marker for subjects and sites vulnerable to bone loss in a longitudinal model of aggressive periodontitis. PLoS ONE 5:e98541. doi: 10.1371/journal.pone.0098541

PubMed Abstract | CrossRef Full Text | Google Scholar

Fine, D. H., Markowitz, K., Furgang, D., Fairlie, K., Ferrandiz, J., Nasri, C., et al. (2009). Macrophage inflammatory protein-1alpha: a salivary biomarker of bone loss in a longitudinal cohort study of children at risk for aggressive periodontal disease? J. Periodontol. 80, 106–113. doi: 10.1902/jop.2009.080296

PubMed Abstract | CrossRef Full Text | Google Scholar

Frodge, B. D., Ebersole, J. L., Kryscio, R. J., Thomas, M. V., and Miller, C. S. (2008). Bone remodeling biomarkers of periodontal disease in saliva. J. Periodontol. 79, 1913–1919. doi: 10.1902/jop.2008.080070

PubMed Abstract | CrossRef Full Text | Google Scholar

Gaster, R. S., Hall, D. A., Nielsen, C. H., Osterfeld, S. J., Yu, H., Mach, K. E., et al. (2009). Matrix-insensitive protein assays push the limits of biosensors in medicine. Nat. Med. 15, 1327–1332. doi: 10.1038/nm.2032

PubMed Abstract | CrossRef Full Text | Google Scholar

Gheren, L. W., Cortelli, J. R., Rodrigues, E., Holzhausen, M., and Saad, W. A. (2008). Periodontal therapy reduces arginase activity in saliva of patients with chronic periodontitis. Clin. Oral Investig. 12, 67–72. doi: 10.1007/s00784-007-0146-8

PubMed Abstract | CrossRef Full Text | Google Scholar

Glimvall, P., Wickström, C., and Jansson, H. (2012). Elevated levels of salivary lactoferrin, a marker for chronic periodontitis? J. Periodontal Res. 47, 655–660. doi: 10.1111/j.1600-0765.2012.01479.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Göhler, A., Hetzer, A., Holtfreter, B., Geisel, M. H., Schmidt, C. O., Steinmetz, I., et al. (2014). Quantitative molecular detection of putative periodontal pathogens in clinically healthy and periodontally diseased subjects. PLoS ONE 9:e99244. doi: 10.1371/journal.pone.0099244

PubMed Abstract | CrossRef Full Text | Google Scholar

Górska, R., and Nedzi-Góra, M. (2006). The effects of the initial treatment phase and of adjunctive low-dose doxycycline therapy on clinical parameters and MMP-8, MMP-9, and TIMP-1 levels in the saliva and peripheral blood of patients with chronic periodontitis. Arch. Immunol. Ther. Exp. 54, 419–426. doi: 10.1007/s00005-006-0047-6

PubMed Abstract | CrossRef Full Text | Google Scholar

Griffen, A. L., Beall, C. J., Campbell, J. H., Firestone, N. D., Kumar, P. S., Yang, Z. K., et al. (2012). Distinct and complex bacterial profiles in human periodontitis and health revealed by 16S pyrosequencing. ISME J. 6, 1176–1185. doi: 10.1038/ismej.2011.191

PubMed Abstract | CrossRef Full Text | Google Scholar

Groenink, J., Walgreen-Weterings, E., Nazmi, K., Bolscher, J. G., Veerman, E. C., van Winkelhoff, A. J., et al. (1999). Salivary lactoferrin and low-Mr mucin MG2 in Actinobacillus actinomycetemcomitans-associated periodontitis. J. Clin. Periodontol. 26, 269–275. doi: 10.1034/j.1600-051X.1999.260501.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Gubala, V., Harris, L. F., Ricco, A. J., Tan, M. X., and Williams, D. E. (2012). Point of care diagnostics: status and future. anal chem. point of care diagnostics: status and future. Anal. Chem. 84, 487–515. doi: 10.1021/ac2030199

PubMed Abstract | CrossRef Full Text | Google Scholar

Gursoy, U. K., Könönen, E., Huumonen, S., Tervahartiala, T., Pussinen, P. J., Suominen, A. L., et al. (2013). Salivary type I collagen degradation end-products and related matrix metalloproteinases in periodontitis. J. Clin. Periodontol. 40, 18–25. doi: 10.1111/jcpe.12020

PubMed Abstract | CrossRef Full Text | Google Scholar

Gursoy, U. K., Könönen, E., Pradhan-Palikhe, P., Tervahartiala, T., Pussinen, P. J., Suominen-Taipale, L., et al. (2010). Salivary MMP-8, TIMP-1, and ICTP as markers of advanced periodontitis. J. Clin. Periodontol. 37, 487–493. doi: 10.1111/j.1600-051X.2010.01563.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Gursoy, U. K., Könönen, E., Uitto, V. J., Pussinen, P. J., Hyvärinen, K., Suominen-Taipale, L., et al. (2009). Salivary interleukin-1beta concentration and the presence of multiple pathogens in periodontitis. J. Clin. Periodontol. 36, 922–927. doi: 10.1111/j.1600-051X.2009.01480.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Halpin, S. T., and Spence, D. M. (2010). Direct plate-reader measurement of nitric oxide released from hypoxic erythrocytes flowing through a microfluidic device. Anal. Chem. 82, 7492–7497. doi: 10.1021/ac101130s

PubMed Abstract | CrossRef Full Text | Google Scholar

Han, D. H., Kim, M. S., Shin, H. S., Park, K. P., and Kim, H. D. (2013). Association between periodontitis and salivary nitric oxide metabolites among community elderly Koreans. J. Periodontol. 84, 776–784. doi: 10.1902/jop.2012.120237

PubMed Abstract | CrossRef Full Text | Google Scholar

Hassan, S. H., El-Refai, M. I., Ghallab, N. A., Kasem, R. F., and Shaker, O. G. (2015). Effect of periodontal surgery on osteoprotegerin levels in gingival crevicular fluid, saliva, and gingival tissues of chronic periodontitis patients. Dis. Markers 2015:341259. doi: 10.1155/2015/341259

PubMed Abstract | CrossRef Full Text | Google Scholar

Hayakawa, H., Yamashita, K., Ohwaki, K., Sawa, M., Noguchi, T., Iwata, K., et al. (1994). Collagenase activity and tissue inhibitor of metalloproteinases-1 (TIMP-1) content in human whole saliva from clinically healthy and periodontally diseased subjects. J. Periodontal Res. 29, 305–308. doi: 10.1111/j.1600-0765.1994.tb01226.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Hendek, M. K., Erdemir, E. O., and Kisa, U. (2015). Evaluation of salivary procalcitonin levels in different periodontal diseases. J. Periodontol. 86, 820–826. doi: 10.1902/jop.2015.130751

PubMed Abstract | CrossRef Full Text | Google Scholar

Herr, A. E., Hatch, A. V., Giannobile, W. V., Throckmorton, D. J., Tran, H. M., Brennan, J. S., et al. (2007a). Integrated microfluidic platform for oral diagnostics. Ann. N.Y. Acad. Sci. 1098, 362–374. doi: 10.1196/annals.1384.004

PubMed Abstract | CrossRef Full Text | Google Scholar

Herr, A. E., Hatch, A. V., Throckmorton, D. J., Tran, H. M., Brennan, J. S., Giannobile, W. V., et al. (2007b). Microfluidic immunoassays as rapid saliva-based clinical diagnostics. Proc. Natl. Acad. Sci. U.S.A. 27, 5268–5273. doi: 10.1073/pnas.0607254104

PubMed Abstract | CrossRef Full Text | Google Scholar

Isaza-Guzmán, D. M., Arias-Osorio, C., Martínez-Pabón, M. C., and Tobón-Arroyave, S. I. (2011). Salivary levels of matrix metalloproteinase (MMP)-9 and tissue inhibitor of matrix metalloproteinase (TIMP)-1: a pilot study about the relationship with periodontal status and MMP-9(- 1562C/T) gene promoter polymorphism. Arch. Oral Biol. 56, 401–411. doi: 10.1016/j.archoralbio.2010.10.021

PubMed Abstract | CrossRef Full Text | Google Scholar

Isaza-Guzmán, D. M., Aristizábal-Cardona, D., Martínez-Pabón, M. C., Velásquez-Echeverri, H., and Tobón-Arroyave, S. I. (2008). Estimation of sCD14 levels in saliva obtained from patients with various periodontal conditions. Oral Dis. 14, 450–456. doi: 10.1111/j.1601-0825.2007.01400.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Isaza-Guzmán, D. M., Cardona-Vélez, N., Gaviria-Correa, D. E., Martínez-Pabón, M. C., Castaño-Granada, M. C., and Tobón-Arroyave, S. I. (2015). Association study between salivary levels of interferon (IFN)-gamma, interleukin (IL)-17, IL-21, and IL-22 with chronic periodontitis. Arch. Oral Biol. 60, 91–99. doi: 10.1016/j.archoralbio.2014.09.002

PubMed Abstract | CrossRef Full Text | Google Scholar

Jentsch, H., Sievert, Y., and Göcke, R. (2004). Lactoferrin and other markers from gingival crevicular fluid and saliva before and after periodontal treatment. J. Clin. Periodontol. 31, 511–514. doi: 10.1111/j.1600-051X.2004.00512.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Ji, S., Choi, Y. S., and Choi, Y. (2014). Bacterial invasion and persistence: critical events in the pathogenesis of periodontitis? J. Periodontal Res. doi: 10.1111/jre.12248. [Epub ahead of print].

PubMed Abstract | CrossRef Full Text | Google Scholar

Katsarelis, H., Shah, N. P., Dhariwal, D. K., and Pazianas, M. (2015). Infection and medication-related osteonecrosis of the jaw. J. Dent. Res. 94, 534–539. doi: 10.1177/0022034515572021

PubMed Abstract | CrossRef Full Text | Google Scholar

Khalaf, H., Lönn, J., and Bengtsson, T. (2014). Cytokines and chemokines are differentially expressed in patients with periodontitis: possible role for TGF-β1 as a marker for disease progression. Cytokine 67, 29–35. doi: 10.1016/j.cyto.2014.02.007

PubMed Abstract | CrossRef Full Text | Google Scholar

Khorsavi Samani, M., Poorsattar Bejeh Mir, A., Kashiri, M., and Gujeq, D. (2012). Introducing cut-points for salivary nitric oxide to distinguish periodontitis from the normal periodontium. Minerva Stomatol. 61, 443–448.

PubMed Abstract | Google Scholar

Kobayashi, T., and Yoshie, H. (2015). Host responses in the link between periodontitis and rheumatoid arthritis. Curr. Oral Health Rep. 2, 1–8. doi: 10.1007/s40496-014-0039-2

PubMed Abstract | CrossRef Full Text | Google Scholar

Kugahara, T., Shosenji, Y., and Ohashi, K. (2008). Screening for periodontitis in pregnant women with salivary enzymes. J. Obstet. Gynaecol. Res. 34, 40–46. doi: 10.1111/j.1447-0756.2007.00681.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Lamster, I. B., Kaufman, E., Grbic, J. T., Winston, L. J., and Singer, R. E. (2003). β-glucuronidase activity in saliva: relationship to clinical periodontal parameters. J. Periodontol. 74, 353–359. doi: 10.1902/jop.2003.74.3.353

PubMed Abstract | CrossRef Full Text | Google Scholar

Lang, N. P., Adler, R., Joss, A., and Nyman, S. (1990). Absence of bleeding on probing. An indicator of periodontal stability. J. Clin. Periodontol. 17, 714–721. doi: 10.1111/j.1600-051X.1990.tb01059.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Lauks, I. R. (1998). Microfabricated biosensors and microanalytical systems for blood analysis. Acc. Chem. Res. 31, 317–324. doi: 10.1021/ar9700670

CrossRef Full Text | Google Scholar

Lönn, J., Johansson, C. S., Nakka, S., Palm, E., Bengtsson, T., Nayeri, F., et al. (2014). High concentration but low activity of hepatocyte growth factor in periodontitis. J. Periodontol. 85, 113–122. doi: 10.1902/jop.2013.130003

PubMed Abstract | CrossRef Full Text | Google Scholar

McManus, L. M., and Pinckard, R. N. (2000). PAF, a putative mediator of oral inflammation. Crit. Rev. Oral Biol. Med. 11, 240–258. doi: 10.1177/10454411000110020701

PubMed Abstract | CrossRef Full Text | Google Scholar

Meschiari, C. A., Marcaccini, A. M., Santos Moura, B. C., Zuardi, L. R., Tanus-Santos, J. E., and Gerlach, R. F. (2013). Salivary MMPs, TIMPs, and MPO levels in periodontal disease patients and controls. Clin. Chim. Acta. 5, 140–146. doi: 10.1016/j.cca.2013.03.008

PubMed Abstract | CrossRef Full Text | Google Scholar

Miller, C. S., Foley, J. D., Bailey, A. L., Campell, C. L., Humphries, R. L., Christodoulides, N., et al. (2010). Current developments in salivary diagnostics. Biomark. Med. 4, 171–189. doi: 10.2217/bmm.09.68

PubMed Abstract | CrossRef Full Text | Google Scholar

Miller, C. S., King, C. P. Jr. Langub, M. C., Kryscio, R. J., and Thomas, M. V. (2006). Salivary biomarkers of existing periodontal disease: a cross-sectional study. J. Am. Dent. Assoc. 137, 322–329. doi: 10.14219/jada.archive.2006.0181

PubMed Abstract | CrossRef Full Text | Google Scholar

Mirrielees, J., Crofford, L. J., Lin, Y., Kryscio, R. J., Dawson, D. R. III, Ebersole, J. L., et al. (2010). Rheumatoid arthritis and salivary biomarkers of periodontal disease. J. Clin. Periodontol. 37, 1068–1074. doi: 10.1111/j.1600-051X.2010.01625.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Ng, P. Y., Donley, M., Hausmann, E., Hutson, A. D., Rossomando, E. F., and Scannapieco, F. A. (2007). Candidate salivary biomarkers associated with alveolar bone loss: cross-sectional and in vitro studies. FEMS Immunol. Med. Microbiol. 49, 252–260. doi: 10.1111/j.1574-695X.2006.00187.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Nomura, Y., Shimada, Y., Hanada, N., Numabe, Y., Kamoi, K., Sato, T., et al. (2012). Salivary biomarkers for predicting the progression of chronic periodontitis. Arch. Oral Biol. 57, 413–420. doi: 10.1016/j.archoralbio.2011.09.011

PubMed Abstract | CrossRef Full Text | Google Scholar

Nomura, Y., Tamaki, Y., Tanaka, T., Arakawa, H., Tsurumoto, A., Kirimura, K., et al. (2006). Screening of periodontitis with salivary enzyme tests. J. Oral Sci. 48, 177–183. doi: 10.2334/josnusd.48.177

PubMed Abstract | CrossRef Full Text | Google Scholar

Nový, B. B. (2014). Saliva and biofilm-based diagnostics: a critical review of the literature concerning sialochemistry. J. Evid. Based Dent. Pract. 14(Suppl.), 27–32. doi: 10.1016/j.jebdp.2014.04.004

PubMed Abstract | CrossRef Full Text | Google Scholar

Özcan, E., Saygun, N. I., Serdar, M. A., and Kurt, N. (2015). Evaluation of the salivary levels of visfatin, chemerin, and progranulin in periodontal inflammation. Clin. Oral Investig. 19, 921–928. doi: 10.1007/s00784-014-1308-0

PubMed Abstract | CrossRef Full Text | Google Scholar

Ozmeriç, N., Elgün, S., and Uraz, A. (2000). Salivary arginase in patients with adult periodontitis. Clin. Oral Investig. 4, 21–24. doi: 10.1007/s007840050108

PubMed Abstract | CrossRef Full Text | Google Scholar

Ozmeriç, N., Baydar, T., Bodur, A., Engin, A. B., Uraz, A., Eren, K., et al. (2002). Level of neopterin, a marker of immune cell activation in gingival crevicular fluid, saliva, and urine in patients with aggressive periodontitis. J. Periodontol. 73, 720–725. doi: 10.1902/jop.2002.73.7.720

PubMed Abstract | CrossRef Full Text | Google Scholar

Parwani, S. R., Chitnis, P. J., and Parwani, R. N. (2012). Salivary nitric oxide levels in inflammatory periodontal disease – a case-control and interventional study. Int. J. Dent. Hyg. 10, 67–73. doi: 10.1111/j.1601-5037.2011.00508.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Pederson, E. D., Stanke, S. R., Whitener, S. J., Sebastiani, P. T., Lamberts, B. L., and Turner, D. W. (1995). Salivary levels of alpha 2-macroglobulin, alpha 1-antitrypsin, C-reactive protein, cathepsin G and elastase in humans with or without destructive periodontal disease. Arch. Oral Biol. 40, 1151–1155. doi: 10.1016/0003-9969(95)00089-5

PubMed Abstract | CrossRef Full Text | Google Scholar

Pereira, A. L., Cortelli, S. C., Aquino, D. R., Franco, G. C., Cogo, K., Rodrigues, E., et al. (2012). Reduction of salivary arginine catabolic activity through periodontal therapy. Quintessence Int. 43, 777–787.

PubMed Abstract | Google Scholar

Pietruska, M., Bernaczyk, A., Knas, M., Pietruski, J., and Zwierz, K. (2006). Assessment of salivary levels of the chosen exoglycosidases in patients with aggressive periodontitis after treatment with doxycycline. Adv. Med. Sci. 51, 158–161.

PubMed Abstract | Google Scholar

Prakasam, S., and Srinivasan, M. (2014). Evaluation of salivary biomarker profiles following non-surgical management of chronic periodontitis. Oral Dis. 20, 171–177. doi: 10.1111/odi.12085

PubMed Abstract | CrossRef Full Text | Google Scholar

Ramseier, C. A., Kinney, J. S., Herr, A. E., Braun, T., Sugai, J. V., Shelburne, C. A., et al. (2009). Identification of pathogen and host-response markers correlated with periodontal disease. J. Periodontol. 80, 436–446. doi: 10.1902/jop.2009.080480

PubMed Abstract | CrossRef Full Text | Google Scholar

Rathnayake, N., Akerman, S., Klinge, B., Lundegren, N., Jansson, H., Tryselius, Y., et al. (2013). Salivary biomarkers of oral health: a cross-sectional study. J. Clin. Periodontol. 40, 140–147. doi: 10.1111/jcpe.12038

PubMed Abstract | CrossRef Full Text | Google Scholar

Reher, V. G., Zenóbio, E. G., Costa, F. O., Reher, P., and Soares, R. V. (2007). Nitric oxide levels in saliva increase with severity of chronic periodontitis. J. Oral Sci. 49, 271–276. doi: 10.2334/josnusd.49.271

PubMed Abstract | CrossRef Full Text | Google Scholar

Rissin, D. M., Kan, C. W., Campbell, T. G., Howes, S. C., Fournier, D. R., Song, L., et al. (2010). Single-molecule enzyme-linked immunosorbent assay detects serum proteins at subfemtomolar concentrations. Nat. Biotechnol. 28, 595–599. doi: 10.1038/nbt.1641

PubMed Abstract | CrossRef Full Text | Google Scholar

Rudney, J. D., Kajander, K. C., and Smith, Q. T. (1985). Correlations between human salivary levels of lysozyme, lactoferrin, salivary peroxidase and secretory immunoglobulin A with different stimulatory states and over time. Arch. Oral Biol. 30, 765–771. doi: 10.1016/0003-9969(85)90129-3

PubMed Abstract | CrossRef Full Text | Google Scholar

Rudrakshi, C., Srinivas, N., and Mehta, D. S. (2011). A comparative evaluation of hepatocyte growth factor levels in gingival crevicular fluid and saliva and its correlation with clinical parameters in patients with and without chronic periodontitis: a clinico-biochemical study. J. Indian Soc. Periodontol. 15, 147–151. doi: 10.4103/0972-124X.84384

PubMed Abstract | CrossRef Full Text | Google Scholar

Sackmann, E. K., Fulton, A. L., and Beebe, D. J. (2014). The present and future role of microfluidics in biomedical research. Nature 13, 181–189. doi: 10.1038/nature13118

PubMed Abstract | CrossRef Full Text | Google Scholar

Salvi, G. E., Lindhe, J., and Lang, N. P. (2008). “Examination of patients with periodontal diseases,” in Clinical Periodontology and Implant Dentistry, eds N. P. Lang and J. Lindhe (Oxford: Munksgaard), 573–586.

Google Scholar

Sawamoto, Y., Sugano, N., Tanaka, H., and Ito, K. (2005). Detection of periodontopathic bacteria and an oxidative stress marker in saliva from periodontitis patients. Oral Microbiol. Immunol. 20, 216–220. doi: 10.1111/j.1399-302X.2005.00215.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Saygun, I., Nizam, N., Keskiner, I., Bal, V., Kubar, A., Açikel, C., et al. (2011). Salivary infectious agents and periodontal disease status. J. Periodontal Res. 46, 235–239. doi: 10.1111/j.1600-0765.2010.01335.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Scannapieco, F. A. (2005). Systemic effects of periodontal diseases. Dent. Clin. North Am. 49, 533–550. doi: 10.1016/j.cden.2005.03.002

PubMed Abstract | CrossRef Full Text

Scannapieco, F. A., Ng, P., Hovey, K., Hausmann, E., Hutson, A., and Wactawski-Wende, J. (2007). Salivary biomarkers associated with alveolar bone loss. Ann. N.Y. Acad. Sci. 1098, 496–497. doi: 10.1196/annals.1384.034

PubMed Abstract | CrossRef Full Text | Google Scholar

Sezer, U., Ciçek, Y., and Canakçi, C. F. (2012). Increased salivary levels of 8-hydroxydeoxyguanosine may be a marker for disease activity for periodontitis. Dis. Markers 32, 165–172. doi: 10.3233/DMA-2011-0876

PubMed Abstract | CrossRef Full Text | Google Scholar

Shojaee, M., Fereydooni Golpasha, M., Maliji, G., Bijani, A., Aghajanpour Mir, S. M., and Mousavi Kani, S. N. (2013). C – reactive protein levels in patients with periodontal disease and normal subjects. Int. J. Mol. Cell. Med. 2, 151–155.

PubMed Abstract | Google Scholar

Sia, S. K., and Chin, C. D. (2011). Analytical chemistry: sweet solution to sensing. Nature Chem. 3, 659–660. doi: 10.1038/nchem.1119

PubMed Abstract | CrossRef Full Text | Google Scholar

Song, Y., Huang, Y. Y., Liu, X., Zhang, X., Ferrari, M., and Qin, L. (2014). Point-of-care technologies for molecular diagnostics using a drop of blood. Trends. Biotechnol. 32, 132–139. doi: 10.1016/j.tibtech.2014.01.003

PubMed Abstract | CrossRef Full Text | Google Scholar

Souto, R., Silva-Boghossian, C. M., and Colombo, A. P. (2014). Prevalence of Pseudomonas aeruginosa and Acinetobacter spp. in subgingival biofilm and saliva of subjects with chronic periodontal infection. Braz. J. Microbiol. 45, 495–501. doi: 10.1590/S1517-83822014000200017

PubMed Abstract | CrossRef Full Text | Google Scholar

Su, W., Gao, X., Jiang, L., and Qin, J. (2015). Microfluidic platform towards point-of-care diagnostics in infectious diseases. J. Chromatogr. A 16, 13–26. doi: 10.1016/j.chroma.2014.12.041

PubMed Abstract | CrossRef Full Text | Google Scholar

Sugano, N., Yokoyama, K., Oshikawa, M., Kumagai, K., Takane, M., Tanaka, H., et al. (2003). Detection of Streptococcus anginosus and 8-hydroxydeoxyguanosine in saliva. J. Oral Sci. 45, 181–184. doi: 10.2334/josnusd.45.181

PubMed Abstract | CrossRef Full Text | Google Scholar

Sundar, N. M., Krishnan, V., Krishnaraj, S., Hemalatha, V. T., and Alam, M. N. (2013). Comparison of the salivary and the serum nitric oxide levels in chronic and aggressive periodontitis: a biochemical study. J. Clin. Diagn. Res. 7, 1223–1227. doi: 10.7860/JCDR/2013/5386.3068

PubMed Abstract | CrossRef Full Text | Google Scholar

Sutej, I., Peros, K., Benutic, A., Capak, K., Basic, K., and Rosin-Grget, K. (2012). Salivary calcium concentration and periodontal health of young adults in relation to tobacco smoking. Oral Health Prev. Dent. 10, 397–403.

PubMed Abstract | Google Scholar

Takane, M., Sugano, N., Ezawa, T., Uchiyama, T., and Ito, K. (2005). A marker of oxidative stress in saliva: association with periodontally-involved teeth of a hopeless prognosis. J. Oral Sci. 47, 53–57. doi: 10.2334/josnusd.47.53

PubMed Abstract | CrossRef Full Text | Google Scholar

Taylor, J. J. (2014). Protein biomarkers of periodontitis in saliva. ISRN Inflamm. 22, 593151. doi: 10.1155/2014/593151

PubMed Abstract | CrossRef Full Text | Google Scholar

Teles, R. P., Likhari, V., Socransky, S. S., and Haffajee, A. D. (2009). Salivary cytokine levels in subjects with chronic periodontitis and in periodontally healthy individuals: a cross-sectional study. J. Periodontal Res. 44, 411–417. doi: 10.1111/j.1600-0765.2008.01119.x

PubMed Abstract | CrossRef Full Text | Google Scholar

Tobón-Arroyave, S. I., Isaza-Guzmán, D. M., Restrepo-Cadavid, E. M., Zapata-Molina, S. M., and Martínez-Pabón, M. C. (2012). Association of salivary levels of the bone remodelling regulators sRANKL and OPG with periodontal clinical status. J. Clin. Periodontol. 39, 1132–1140. doi: 10.1111/jcpe.12012

PubMed Abstract | CrossRef Full Text | Google Scholar

Tobon-Arroyave, S. I., Jaramillo-Gonzalez, P. E., and Isaza-Guzman, D. M. (2008). Correlation between salivary IL-1β levels and periodontal clinical status. Arch. Oral Biol. 53, 346–352. doi: 10.1016/j.archoralbio.2007.11.005

PubMed Abstract | CrossRef Full Text | Google Scholar

Toh, S. Y., Citartan, M., Gopinath, S. C., and Tang, T. H. (2015). Aptamers as a replacement for antibodies in enzyme-linked immunosorbent assay. Biosens. Bioelectron. 64, 392–403. doi: 10.1016/j.bios.2014.09.026

PubMed Abstract | CrossRef Full Text | Google Scholar

Totan, A., Greabu, M., Totan, C., and Spinu, T. (2006). Salivary aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase: possible markers in periodontal diseases? Clin. Chem. Lab. Med. 44, 612–615. doi: 10.1515/cclm.2006.096

PubMed Abstract | CrossRef Full Text | Google Scholar

von Troil-Lindén, B., Torkko, H., Alaluusua, S., Jousimies-Somer, H., and Asikainen, S. (1995). Salivary levels of suspected periodontal pathogens in relation to periodontal status and treatment. J. Dent. Res. 74, 1789–1795. doi: 10.1177/00220345950740111201

PubMed Abstract | CrossRef Full Text | Google Scholar

Warsinke, A. (2009). Point-of-care testing of proteins. Anal. Bioanal. Chem. 393, 1393–1405. doi: 10.1007/s00216-008-2572-0

PubMed Abstract | CrossRef Full Text | Google Scholar

Wilczynska-Borawska, M., Borawski, J., Kovalchuk, O., Chyczewski, L., and Stokowska, W. (2006). Hepatocyte growth factor in saliva is a potential marker of symptomatic periodontal disease. J. Oral Sci. 48, 47–50. doi: 10.2334/josnusd.48.47

PubMed Abstract | CrossRef Full Text | Google Scholar

Wilkins, E., and Atanasov, P. (1996). Glucose monitoring: state of the art and future possibilities. Med. Eng. Phys. 18, 273–288. doi: 10.1016/1350-4533(95)00046-1

PubMed Abstract | CrossRef Full Text | Google Scholar

Yang, J., Wei, F., Schafer, C., and Wong, D. T. (2014). Detection of tumor cell-specific mRNA and protein in exosome-like microvesicles from blood and saliva. PLoS ONE 14:e110641. doi: 10.1371/journal.pone.0110641

PubMed Abstract | CrossRef Full Text | Google Scholar

Yoon, A. J., Cheng, B., Philipone, E., Turner, R., and Lamster, I. B. (2012). Inflammatory biomarkers in saliva: assessing the strength of association of diabetes mellitus and periodontal status with the oral inflammatory burden. J. Clin. Periodontol. 39, 434–440. doi: 10.1111/j.1600-051X.2012.01866.x

PubMed Abstract | CrossRef Full Text | Google Scholar