m3 supporting structures (PDL, cementum, alveolar process, pulp)

p2

periodontal ligament

dense connective tissue attaching the tooth to the alveolar bone

0.1 - 0.25 mm

thickness of periodontal ligament

supportive and protective

formative

sensory

nutritive

functions of periodontal ligament

supportive and protective

PDL acts as a shock absorbing making sure the occlusal forces are well distributed and would not cause trauma to the teeth

formative

• reaction from the PDL could signal the activation of osteoblasts, cementoblasts, and fibroblasts

sensory

• PDL contains both sensory and autonomous nerve endings which give it the ability to estimate the amount of pressure during mastication and to identify which tooth is being percussed

nutritive

due to the presence of blood supply from the branches of the alveolar and interradicular arteries

transseptal fibers

alveolar crest fibers

horizontal fibers

oblique fibers

apical fibers

interradicular fibers

what are the principal periodontal fiber groups

transseptal fibers

embedded into the cementum of adjacent teeth and extends interproximally over the alveolar crest

alveolar crest fibers

extends obliquely from the cementum beneath the junctional epithelium to the alveolar crest

horizontal fibers

extends at right angle to the long axis of the tooth between cementum and alveolar bone

oblique fibers

largest group of principal periodontal fibers, extending from the cementum obliquely to the alveolar bone

apical fibers

radiates from the apical cementum to the alveolar bone at the base of the socket

interradicular fibers

courses over the crest of the interradicular septum in the furcations of multirooted teeth

cementum

mineralized connective tissue that covers the roots of teeth

cementum

to attach the periodontal ligament fibers to the teeth

cementum

contains cementoblasts, cementoclasts, and cementocytes

according to location

according to cellularity

according to presence or absence of collagen fibrils

classification of cementum

Iradicular cementum

coronal cementum

according to location (cementum)

cellular cementum

acellular cementum

according to cellularity (cementum)

fibrillar cementum

afibrillar cementum

according to presence or absence of collagen fibrils (cementum)

acellular fibrillar cementum

cellular fibrillar cementum

types of cementum

ACELLULAR FIBRILLAR CEMENTUM

covers the coronal half of the root

devoid of cells

CELLULAR FIBRILLAR CEMENTUM

covers the apical half of the root and the furcation of multirooted teeth

cementocytes are noted

enamel projections

hypercementosis

enamel pearls

cementicles

DEVELOPMENTAL & ACQUIRED ANOMALIES ASSOCIATED WITH CEMENTOGENESIS

enamel projections

extension of enamel beyond the cervical margin

hypercementosis

• cemental dysplasia

• excess cementum is formed on the root, most commonly affecting the apical third

enamel pearls

droplets of ectopic enamel occasionally found on the roots of teeth, most commonly in the bifurcation or trifurcation areas

cementicles

small foci of calcified tissue, not necessarily true cementum, which lie free or attached in the PDL of the lateral and apical root areas

alveolar process

• part of maxilla and mandible that forms and supports the teeth

• contains osteoblasts, osteoclasts, and osteocytes

alveolar bone proper

supporting bone

parts of alveolar process

alveolar bone proper

• consists of thin lamella of bone immediately surrounding the root

supporting bone

surrounds the alveolar bone proper and provides additional functional support

pulp

consists of vascular connective tissue contained within the rigid dentinal walls

alveolar bone proper

• radiopaque lamina dura in radiograph

pulp

contains fibroblasts (for collagen formation, odontoblasts, and defensive cells)

formative

nutritive

sensory

defensive

functions of pulp

formative

involved in the support, maintenance, and continuous formation of dentin

nutritive

provides blood supply for the tooth via either arteries or arterioles that enter the pulp at its apical termination and course coronally, increasing and branching into capillaries subjacent to the odontoblastic layer

sensory

• perceives thermal, mechanical, and chemical changes via nerves that enter the pulp through the apical foramen with the afferent blood vessels either as accompanying individual units or as intimately associated nerve sheaths

• majority of sensory receptors on the dental nerves are free nerve endings

defensive

provides inflammatory and immune response via histiocytes/wandering cells, undifferentiated mesenchymal cells, polymorphonuclear leukocytes, lymphocytes, plasma cells, and eosinophils

• decrease in cellular components

• dentinal sclerosis

• decrease in the number and quality of blood vessels and nerves

• reduction in size and volume of the pulp owing to continued dentin deposition and reparative dentin formation

• increase in number and thickness of collagen fibers

• increase of pulp stones and dystrophic mineralizations

pulpal response to aging