Perio

• Above the cementoenamel junction is the anatomical crown and below is the anatomical root
• Generally, incisors and canines have 1 root, premolars have 1-2 roots, and molars have 2-3 roots
• The number of molar roots depends on the jaw; maxillary molars tend to have more roots
• Root numbers

  A) 1

  B) 1

  C) 1

  D) 1

  E) 1

  F) 1

  G) 2, 1

  H) 1

  I) 1, 2

  J) 1

  K) 3

  L) 2, 3

  M) 3

  N) 2

  O) varies

  P) varies

  
• The cross section of the upper incisors are significantly larger than the lower incisors, as they tend to experience greater forces during mastication
• The furcation is the gap between the roots and is most important for molars
• Above the furcation is the root trunk, and below is the root cone
• In between the roots is the degree of separation
• At the apex of the root is the divergence (how far they are separated)
• The furcation has a fornix (ceiling of the furcation) and entrance (entry point)
• Furcation l

  A) fornix

  B) entrance

  C) CEJ

  D) root trunk

  E) furcation

  F) root cone

  G) degree of separation

  H) divergence

  
• Furcation radiolucency: a shadow on a radiograph between roots, may be indicative of periodontal disease/bone loss
• Periodontal disease is an inflammatory and chronic disease, it is initiated by bacteria and compromised (gets worse) by the immune system
• Periodontal disease is a silent disease with no symptoms so it progresses easily; it is also very common
• Periodontal disease is a large collection of diseases that can start from gingivitis (inflammation of the gingiva) to periodontitis (damage to supporting elements of the tooth)
• The prevalence of periodontal disease is difficult to determine as almost everyone has some degree of gingivitis; if defined by the tooth losing connection to the surrounding ligaments, then prevalence is around 20%
• If the bacteria enters the furcation, it is difficult to be cleaned well, especially if the root is concave instead of convex → important consideration for cleaning the root surface
• Degree I: destruction of attachment horizontally within 3mm
• Degree II: destruction of attachment horizontally more than 3mm, but unable to pass through to the other side
• Degree III: “through and through” destruction of attachment in the furcation, can go through the entire tooth
• Cervical enamel projection: the cementoenamel junction extends down to the root, a feature very common in the Hong Kong population
• The gums attach to both the enamel and cementum, but in different ways; attaches to enamel by hemidesmosomes (weaker connection) and to the cementum by attachment, with fibers sticking into the root surface to form a stronger connection → thus cervical enamel projections gives a “fast pass” for bacteria to reach the furcation
• Palato-radicular grooves are quite common especially in lateral incisors, and may be favorable for plaque accumulation due to being difficult to clean
• Enamel pearls are beads of enamel forming on the root; they are less problematic as there is still cementum above the pearl, but once infection reaches it it will become problematic and may be solved by surgical means
• The canine fossa only occurs on the maxillary first premolars, where the roots are fused to produce a groove
• Incomplete root separation is common in Hong Kong populations, especially for the lower second molar
• Dilaceration is where the root experiences certain trauma during formation and grows in an odd shape
• Root anomaly summary

  A) palato-radicular groove

  B) canine fossa

  C) palatal groove

  D) incomplete root separation

  E) incomplete root separation