Exodontia and Impactions


INI CET 2021 May


Inter-radicular bone deposition occurs in:


Bone modelling and remodelling phase


•            During this period, the woven bone is gradually replaced with lamellar bone (e.g. bone remodelling).

•            Bone remodelling occurs concomitantly with bone resorption that takes place on the socket walls resulting in a dimensional reduction in the alveolar ridge (e.g. bone modelling).

•            After 60 and 90 days of healing, a newly formed hard tissue bridge consisting mainly of woven bone is present between the marginal mucosa and the extraction socket.

•            At this stage, most of the woven bone located apically to the hard tissue bridge is replaced by bone marrow consisting of large blood vessels, inflammatory cells and adipocytes.

•            At day 90, woven bone has been replaced in several areas with lamellar bone, while the old bone of the socket wall displayed signs of remodelling.



•            After a period of 120 days following extraction, the marginal woven bone located at the marginal part of the previous socket is covered with lamellar bone.

•            Collagen fibres from the lining mucosa are inserting in the newly formed “cortical bone,” and signs of a periosteum-like structure can be detected.

•            At 180 days following extraction, the coronal part of the extraction socket is composed of mineralized bone consisting of a mixture of woven bone and lamellar bone.

•            Apically to the mineralized bone, a well-organized bone marrow containing a large number of adipocytes and few inflammatory cells along with trabeculae of lamellar bone can be observed. During the interval between days 90 and 180, a decrease in the volume occupied by mineralized bone was observed and replaced gradually by bone marrow.

•            At 180 days, the proportion of the bone marrow amounted to approximately 73% in the coronal, 87% in the lateral and 95% in the apical parts of the defects, respectively.



Key Concept:


•            After surgical removal of mandibular third molars, bone fill can be observed over a period of at least 12 months, with the most substantial change (e.g. the greatest bone fill) occurring during the first 3 months after surgery.

•            However, complete fill of these residual bone defects does not always occur.