热病，肾绝，齿黄落，色如熟小豆，或齿忽变黑者死。久病龈肉软却；齿长而垢，或齿光无
垢者死。（此所谓大骨枯槁也。）口开，前板齿燥者，伤暑也。（《脉经》。）
齿龈无色，舌上尽白，唇里有疮者， 也。（按∶即狐惑也。出巢氏。）
温热病，看舌之后，亦须验齿。齿为肾之余，龈为胃之络。热邪不燥胃津，必耗肾液，且二经之血，皆
走其地，病深动血，结瓣于上。阳血者，色必紫，紫如干漆。阴血者，色必黄，黄如酱瓣。阳血若见，安胃
为主。阴血若见，救肾为要。然豆瓣色者，多险，若证还不逆者，尚可治，否
则，难为矣。何以故耶，盖阴下竭，阳上厥也。
齿若光燥如石者，胃热甚也，若无汗恶寒，卫偏
胜也，辛凉泄卫，透汗为要。若如枯骨色者，肾液枯也。若上半截润，（靠根半截。）水不上承，心火上
炎也，急急清心救水，俟枯处转润为妥。（此必充发水中真气，方能有效，非仅甘润凉降所能为也。）
若切牙啮齿者，湿热化风痉病。但切牙者，胃热气走其络也。若切牙而脉证皆衰者，胃虚无谷以内荣，
亦切牙也。何以故耶。虚则喜实也。舌本不缩而硬，而牙关咬定难开者，此非风痰阻络，即欲作痉证，
用酸物擦之即开，木来泄土故也。（风能化燥，酸即生津。）
若齿垢如灰糕样者，胃气无权，津亡，湿浊用事，多死。而初病齿缝流清血，痛者，胃火冲激也；不
痛者，龙火内燔也。（总是悍气，窜入血道。）齿焦无垢者，死，齿焦有垢者，肾热
劫胃也，当微下之，或玉女煎，清胃救肾可也。（《温热论》。）
齿根于冲督之脉，故小儿齿出迟者，以鹿茸、肉苁蓉服之。凡小儿齿出偏斜稀疏者，阳明本气不足也。
齿色枯白者，血虚也。齿色黄暗，或带黑，或片片脱下者，面色青黄，此腹中有久冷积，太阳阳明之阳气受
困，累及于冲督也。落齿后，久不出者，肾与督虚也，必重以鹿茸，加补冲督药，否则出必偏斜稀疏，甚者，
不久复碎落也。俗每以为血热，殊不知是虚冷久积，血不流通，内蓄虚火也。若有虫者是湿热，
亦因胃有积滞；若不虚冷，则面色自红润，不惨黯也。
In the course of febrile diseases, if signs of Kidney Qi exhaustion appear—such as teeth turning yellow and falling out with a color resembling ripe small beans, or teeth suddenly turning black—the prognosis is poor, indicating death. In chronic illnesses, if the gingival tissue recedes; the teeth appear elongated with accumulated plaque, or the teeth are shiny but devoid of plaque—the prognosis is poor, indicating death. (This is referred to as "withered large bones.") Mouth opening with dry incisors indicates damage from summerheat. (*Mai Jing*.)
Teeth and gums lacking color, the entire tongue surface being white, and sores inside the lips indicate Hu Huo Disease (Foxes Disease, characterized by oral and genital ulcers). (Note: This refers to Hu Huo Disease. Originating from Chao Yuan-fang's works.)
In warm-heat diseases, after examining the tongue, one must also inspect the teeth. Teeth are the surplus of Kidney essence; gums are the network vessels of the Stomach channel. If pathogenic heat does not dry up Stomach fluids, it will inevitably consume Kidney yin. Furthermore, the blood of these two meridians flows into this area. When the disease is deep and moves the blood, coagulated blood forms瓣 (petals/clots) on the upper part. Yang-type bleeding (bleeding due to excess heat) will be purple in color, like dried lacquer. Yin-type bleeding (bleeding due to deficiency) will be yellowish, like soybean paste. If Yang-type bleeding is observed, treatment should focus on stabilizing the Stomach. If Yin-type bleeding is observed, saving the Kidney is essential. However, cases presenting with a soybean-paste color are mostly dangerous; if the syndrome has not yet become rebellious, it may still be treatable; otherwise, it is difficult to manage. Why? Because this is due to exhaustion of Yin below and rebellion of Yang above.
If teeth are shiny and dry like stone, it indicates severe Stomach heat. If there is no sweat and aversion to cold, it indicates an excess of Wei (Defensive) Qi; treatment should prioritize using acrid-cool herbs to vent the Defensive level and induce sweating. If teeth resemble the color of dry bones, it indicates exhaustion of Kidney fluids. If the upper half of the teeth is moist (the half near the root), it indicates that Kidney water fails to ascend, and Heart fire flares upward. Urgent clearing of Heart fire and rescue of Kidney water are required, waiting until the dry areas become moist again for safety. (This requires stimulating the true Qi within Water to ascend; it cannot be achieved merely by sweet-moistening and cooling-descending herbs.)
If teeth grinding or clenching occurs, it indicates a spasm disease caused by damp-heat transforming into wind. Mere tooth clenching indicates Stomach heat qi invading the collaterals. If tooth clenching occurs alongside weak pulse and symptoms, it indicates Stomach deficiency where grain essence fails to nourish internally, which also causes clenching. Why? Because extreme deficiency often manifests as apparent excess. If the root of the tongue is stiff without shrinking, and the jaw is locked tight and difficult to open, this is either wind-phlegm obstructing the collaterals or impending spasm disease. Rubbing with sour substances can open the jaw because Wood drains Earth. (Wind transforms into dryness; sour flavors generate body fluids.)
If dental plaque resembles gray cake, it indicates loss of Stomach Qi authority, depletion of fluids, and dominance of turbid dampness, usually leading to death. In early-stage disease, clear blood flowing from between teeth accompanied by pain indicates Stomach fire rushing and striking; absence of pain indicates internal blazing of Dragon Fire (Ministerial Fire). (This is always fierce pathogenic qi intruding into the blood vessels.) Teeth scorched black without plaque indicate death; teeth scorched black with plaque indicate Kidney heat robbing Stomach yin; mild purgation should be used, or Yü Nv Jian (Jade Woman Decoction) to clear Stomach heat and rescue Kidney yin. (*Wen Re Lun*.)
Teeth originate from the Chong and Du vessels. Therefore, children with delayed tooth eruption can be treated with Lu Rong (Deer Antler) and Rou Cong Rong (Cistanche). Children whose teeth erupt obliquely or sparsely suffer from insufficiency of the Yangming primary Qi. Teeth withered and white indicate Blood deficiency. Yellow-dark teeth, or those with black discoloration, or shedding in patches, accompanied by a blue-yellow complexion, indicate long-standing cold accumulation in the abdomen. The Yang Qi of Taiyang and Yangming is constrained, affecting the Chong and Du vessels. After tooth loss, if new teeth fail to emerge for a long time, it indicates deficiency of the Kidney and Du vessel. Heavy use of Lu Rong (Deer Antler) combined with herbs tonifying the Chong and Du vessels is necessary; otherwise, emerging teeth will be oblique and sparse, and severely, they may crumble and fall out shortly thereafter. Laypeople often attribute this to Blood heat, unaware that it is actually long-standing deficiency-cold causing stagnant Blood and internal accumulation of deficient fire. Presence of dental caries indicates damp-heat, also due to food stagnation in the Stomach; if not deficiency-cold, the complexion would naturally be ruddy and vibrant, not dull and dark.