Shedding of teeth Profesor Dr. Akram Yousif Yasear College of Dentistry University of Kerbala Iraq

Shedding The normal physiological process by which the deciduous teeth are removed to allow the succeeding permanent teeth to take their functional position in the mouth. The loss of deciduous teeth is mainly due to the resorption of their roots. Commences earlier in girls than in boys.

Shedding of primary teeth A six year old girl's deciduous teeth, which are beginning to fall out.

Rules of “sixes” in dental development 6 weeks old in utero: beginning of dental development 6 months old: emergence of the first primary tooth 6 years old: emergence of first permanent tooth Source: http://www.columbia.edu/itc/hs/dental/d9903/lectures/lecture4.pdf

Mechanism of shedding Pressure of the succeeding permanent teeth. Increase in force of mastication Action of odontoclast( cementoclast for the cementum and dentinoclast for the dentin) Action of osteoclast which resorbe bone PDL is resorbed by fibroclast

Source: http://www.columbia.edu/itc/hs/dental/d9903/lectures/lecture4.pdf

Essentials of Oral Histology and Embryology. James Avery, 2nd edition

Shedding of anterior teeth

Shedded crown

Eruption for secondary tooth and shedding for posterior deciduous

Cells responsible for shedding

Shedding of Teeth Osteoclast/bone remodeling Odontoclast (cementoclast; dentinoclast) Resorption of soft tissues Pressure from successional teeth Odontoclast Figure Source: Dr. Sandra Meyers

Osteoclasts are bone resorbing cells derived form monocyte- macrophage lineage Giant multinuclear cells with 4-20 nuclei Osteoclasts resorb hard tissue by separating mineral from the collagen matrix through the action of hydrolytic enzymes Resorption occurs at the ruffled border which greatly increases the surface area of the osteoclast in contact with bone Hard Tissue resorption: 1. Extracellular phase 2. Intracellular phase

Resorption in dentin

Odontoclast in a process of resorption of dentin

PDL resorbed by fibroclast

Note the collagen fiber fragments inside the fibroclast (Head arrows)

Osteoclast resorbing the bone

Shedding of anterior teeth

Shedding of posterior teeth

Clinical consideration Remnants of the root of deciduous teeth Retained deciduous teeth Submerged deciduous toth

Retained Primary teeth

Submerged primary teeth Hyper or supra eruption

Impacted maxillary canine

Impacted mandibular third molar