齿为肾之表，舌为心之苗，心气散，则舌出不收。肾气绝，则齿忽啮人。心肾俱绝，则
阴阳相离。(《集成》)
凡小儿生而有齿者大凶，主伤父母，否则必自伤。(陈飞霞)
凡病者齿燥无津，主阳明热病。若舌上焦黑无垢，主十三日死。(顾练澄)
齿为肾之余，龈为胃之络。小儿病，看舌后亦须验齿。(叶天士)
热邪耗肾液者，齿色必黄。黄如酱瓣，宜救肾。(叶天士)
热邪耗胃津者，齿色必紫，紫如干漆，宜安胃。(叶天士)
齿光燥如石者，胃热也。枯骨色者，肾液枯也。若上半截润者，是水不上承，为心火上
炎也。(叶天士)
切牙啮齿者，湿热化风为痉病。但咬不啮者，热甚而牙关紧急也。(周于蕃)
齿垢由肾热蒸胃浊气所结。其色如灰糕，则枯败而精气俱亡，肾胃两竭，为无治。(叶
天士)
齿缝流血者，胃火冲击则痛，如不痛则出于牙根，肾火上炎也。(叶天士)
齿焦者肾水枯，无垢则胃液竭，有垢则火虽盛而液尚未竭也。(叶天士)
齿者，眠睡而齿相磨切也。血气既虚，而风邪又客于牙车筋脉之间，故睡后而邪动引
其筋脉，故上下齿磨切有声，谓之 齿。(《兰台规范》)
齿如热者病难治。(顾练澄)
女子七岁，肾气盛，齿更。(易也，齿落而更易也。)三七，肾气平均，故真牙生而长极
(真牙者，欲所谓尽头牙也。)男子八岁，肾气实，齿更。三八，真牙生。五八，齿槁。八八
，则齿发去。《素问》齿或生或去，皆由肾气盛衰为之。(惕厉子)
按∶齿为骨。骨者，肾之余也，上齿龈为足阳明胃络，下齿龈为手阳明大肠络，载在《
内经
》。后人以上四门牙属心，下四门牙属肾，左右二侧牙，上属胃，下属脾。其余在左之上者
属胆，下者属肝；右之上者属大肠，下者属肺，终不免牵合之弊。叶香岩于诊舌后，必须验
齿，以齿辨证，论热病者居多。齿属肾，肾属水，火极而即以灼水也。(惕厉子)
Teeth are the external manifestation of the Kidney, and the tongue is the sprout of the Heart. When Heart Qi scatters, the tongue protrudes and cannot retract. When Kidney Qi fails, the teeth suddenly bite people. When both Heart and Kidney Qi fail, Yin and Yang separate. (From *Jicheng*)
Infants born with teeth indicate a great omen of misfortune, primarily harming parents; otherwise, it inevitably leads to self-injury. (Chen Feixia)
When a patient's teeth are dry without saliva, it indicates Yangming Heat disease. If the tongue coating is scorched black without turbidity, death is expected within thirteen days. (Gu Liancheng)
Teeth are the surplus of the Kidney, and the gums are the collaterals of the Stomach. In pediatric diseases, after observing the tongue, one must also examine the teeth. (Ye Tianshi)
When pathogenic heat consumes Kidney fluids, the teeth color becomes yellow. If yellow like soybean paste flakes, one should rescue the Kidney. (Ye Tianshi)
When pathogenic heat consumes Stomach fluids, the teeth color becomes purple. If purple like dried lacquer, one should stabilize the Stomach. (Ye Tianshi)
Teeth that are shiny, dry, and hard as stone indicate Stomach Heat. Teeth that are withered and colored like dead bones indicate exhaustion of Kidney fluids. If the upper half of the teeth is moist, it indicates that water fluids fail to ascend, belonging to Heart Fire flaming upward. (Ye Tianshi)
Teeth grinding and clenching indicate Wind-convulsion transformed from Damp-Heat. Merely clenching without grinding indicates extreme Heat causing stiffness of the jaw. (Zhou Yufan)
Dental calculus forms from Kidney heat steaming and condensing Stomach turbid qi. If its color resembles gray cake, it indicates collapse of essence and qi, exhaustion of both Kidney and Stomach, representing an untreatable condition. (Ye Tianshi)
Bleeding from the gum margins: if caused by Stomach fire attacking, there is pain; if painless, it stems from loose tooth roots, indicating Kidney Fire flaming upward. (Ye Tianshi)
Blackened teeth indicate exhaustion of Kidney Water. Lack of dental calculus indicates exhaustion of Stomach fluids. Presence of dental calculus indicates that although Fire is abundant, fluids have not yet been exhausted. (Ye Tianshi)
"Xie Chi" refers to the phenomenon of teeth rubbing against each other during sleep. Due to deficiency of Blood and Qi, and Wind pathogen lodging in the tendons and vessels of the masseter muscle, the pathogen disturbs and pulls these tendons during sleep, causing audible grinding of the upper and lower teeth, termed "Xie Chi". (From *Lantai Guifan*)
Teeth resembling hot coals indicate a difficult-to-treat disease. (Gu Liancheng)
At age seven, girls' Kidney Qi becomes robust, leading to the replacement of deciduous teeth. (Yi means shedding and replacing.) At three times seven (21 years), Kidney Qi is balanced, so wisdom teeth emerge and growth reaches its peak. (True teeth refer to what is commonly called wisdom teeth.) At age eight, boys' Kidney Qi becomes solid, leading to tooth replacement. At three times eight (24 years), wisdom teeth emerge. At five times eight (40 years), teeth become withered. At eight times eight (64 years), teeth and hair fall out. The *Suwen* states that teeth appearing or falling out are all determined by the prosperity or decline of Kidney Qi. (Ti Li Zi)
Note: Teeth belong to the category of Bone. Bone is the surplus of the Kidney. The upper gums are the collaterals of the Foot-Yangming Stomach Meridian, and the lower gums are the collaterals of the Hand-Yangming Large Intestine Meridian, as recorded in the *Neijing*. Later authors claimed the four upper central incisors belong to the Heart, the four lower central incisors to the Kidney, the lateral teeth above to the Stomach, and below to the Spleen. Those on the left above belong to the Gallbladder, below to the Liver; those on the right above to the Large Intestine, below to the Lung. This ultimately suffers from forced association. Ye Xiangyan emphasized examining teeth after diagnosing the tongue to differentiate syndromes, mostly discussing heat diseases. Teeth belong to the Kidney, and the Kidney belongs to Water; extreme Fire burns Water. (Ti Li Zi)