Introduction
The assignment for Lesson 1:3 required each team member to choose a relativity complex term
used within their particular discipline and create a parenthetical, sentence and expanded
definition for this term. The learning objectives included:
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Appreciate the importance and role of definitions in writing
Understand how audience and purpose indicate the need for definition
Differentiate between the levels of detail in definition
Select the right level of detail according to the situation
Parenthetical Definition:
The periodontal ligament (a group of specialized connective tissue fibers) is located around the
root of each tooth.
Sentence Definition:
The periodontal ligament is a part of the periodontium which functions as an attachment site,
anchoring the tooth to the jaw bone.
Expanded Definition;
1. Etymology
The origin of the word periodontal dates back to ancient Greece, with “peri” meaning around and
“odon” meaning tooth. The word ligament is derived from the Latin ligamentum meaning to
bond, and from ligare meaning ‘to bind.’
2. Analysis of Parts
The periodontal ligament is the connective tissue that occupies the space between the root of the
tooth and the jaw bone. Periodontal ligaments are important in dentistry because they help
explain how a tooth is retained in the mouth and how it is able to withstand everyday forces of
brushing, chewing and speaking. These ligaments support the teeth and also relay sensations of
pain, touch, pressure and temperature. The periodontal ligament consists of five subgroups,
which all work together to anchor the tooth within the jaw bone and prevent movement:
A. Alveolar crest fibers: resist extrusive forces, which try to pull the tooth upward, and also resist
side to side tooth movement
B. Horizontal fibers: resist tilting and rotational forces
C. Interradicular fibers – resist rotational forces
D. Oblique fibers: resist intrusive forces, which try to push the tooth inward, as well as rotational
forces
E. Apical fibers: resist tilting, rotational forces, extrusion and intrusion
3. Visual
The following picture identifies the location of each of the five subgroups of the periodontal
ligament, which all work together to anchor the tooth within the jaw bone and prevent
movement. Each subgroup is identified using a distinct colour, allowing for easier
identification. The periodontal ligaments were named according to their location around the root
of the tooth, and the following picture provides a visual for easier recognition.
1. Alveolar Crest Fibers – named because they are the fibers that attach the tooth directly to
the Alveolar Bone (the type of bone that lines the tooth socket)
2. Horizontal Fibers – named because of their horizontal (parallel) orientation
3. Oblique Fibers – named because of their oblique (slanting; neither parallel nor at a right
angle) orientation
4. Apical Fibers – named because they are located at the apex (the tip/bottom of the root) of
the tooth
5. Interradicular Fibers – named because they are located in the interradicular space (the
space found between the roots) of the tooth
Source:
StudyBlue. (2014). The Periodontontium, The Gingiva and Periodontal Ligament. Web. 21 Jan.
2015. Available from:
https://classconnection.s3.amazonaws.com/168/flashcards/673168/jpg/gum41315268163444.jpg
4. Comparison and Contrast
The periodontal ligament develops from similar connective tissue as the jaw bone and has a rich
nerve supply, which allows for detection of even minor forces/disturbances (E.g. metal foil in
candy wrappers). Unlike the connective tissue found within the actual root of the tooth, the
periodontal ligament also transmits pain, touch, pressure and temperature sensations. While
other connective tissues in the mouth often show changes related to aging (e.g. recession of the
gums, alterations is the thickness of gums, wearing and thinning of enamel), the periodontal
ligament is not affected by the again process. It can however undergo drastic changes due to
periodontal disease (an advanced form of gum disease). For example, periodontal disease often
causes the periodontal ligaments to widen or enlarge. This can lead to loss of support, tooth
mobility, infection and ultimately tooth loss.
Works Sited
Bath-Balogn, M & Fehrenbach M. (2007). Illustrated Dental Embryology, Histology and
Anatomy. W.B. Saunders Company
Online Etymonline Dictionary. “Periodontal.” Web. 21 Jan. 2014 Available from:
http://www.etymonline.com/index.php?term=periodontal
Online Etymonline Dictionary. “Ligament.” Web. 21 Jan. 2014. Available from:
http://www.etymonline.com/index.php?term=ligament
StudyBlue. (2014). The Periodontontium, The Gingiva and Periodontal Ligament. Web. 21 Jan.
2015. Available from:
https://classconnection.s3.amazonaws.com/168/flashcards/673168/jpg/gum41315268163444.jpg
Wilkins, E. (2012). Clinical Practice of the Dental Hygienist. Eleventh Edition. Lippincott
Williams & Wilkins.