Trauma from occlusion causes widening of periodontal ligaments and thickening of lamina dura.

Allografts are taken from different individuals of the same species, Xenografts from different species and Isografts from twins.

The inter radicular and apical bones are cancellous in nature.

Trauma from occlusion does not affect epithelial attachment or marginal gingival. Though, it causes enamel wear, cemental tear and widening of PDL along with thickening of lamina dura.

Activity of osteoclasts is modified by calcitonin and parathormone through receptors on osteoclasts.

Dental plaque is a also termed as a biofilm found on tooth surfaces.

Oblique fibres are the largest group among the principal fibres and they are also the ones which bear the brunt of vertical masticatory stresses. They convert them into tension on the alveolar bone.

Horizontal component of the furcation is the parameter that governs the major classification systems of furcation involvement. Naber's probe is specially designed to assess the horizontal component only.

When bone is resorbed by excessive occlusal forces, the body attempts to reinforce the thin bony trabeculae with new bone. This process is called buttressing or lipping.

All the above mentioned drugs can cause hyperplasia of gingival. Anticonvulsants, calcium channel blockers and immune suppressants are the drugs commonly responsible for the same.

Stippling though a feature of attached gingival is seen in only 40% of the individuals.

If blade angle is less than 45 degrees or more than 90 degrees then instead of removing calculus, it would burnish and smoothen it.

 Increased tooth mobility is the characteristic sign of TFO ie: trauma from occlusion.

Refractory Periodontitis was coined in 1989 classification of periodontal diseases. It existed for a decade as a separate disease till 1999 when it was removed from the classification. A new term called recurrent periodontal disease was coined.

Periodontometer is a device invented by Muhlemann. It is a standardized method of measuring even minor tooth displacement. Periotest is a device to measure mobility of teeth as well as implants.