Dental Articulators, Periodontium Anatomy, and Essential Oral Functions

Dental Articulators

An articulator is a mechanical device that represents the temporomandibular joints and jaw members. Maxillary and mandibular casts may be attached to simulate jaw movements.

Uses of Articulators

• Mounting diagnostic casts for diagnosis, treatment planning, and patient presentation.
• Fabrication of occlusal surfaces of dental restorations and lost dental parts.
• Arrangement of artificial teeth for complete and removable partial dentures.

Advantages of Using an Articulator

• Properly mounted casts allow the operator to better visualize the patient’s occlusion.
• When articulating teeth for a complete denture, the lingual view provided by the articulator is essential for developing a proper occlusal scheme.
• Patient cooperation is not a factor when using an articulator.
• Refining complete denture occlusion in the mouth is extremely difficult.
• The patient’s saliva, tongue, and cheek are not factors affecting the procedure.

Minimal Requirements for Articulators

• It should hold casts in the correct horizontal relationships.
• It should hold casts in the correct vertical relationships.
• It should provide a positive anterior vertical stop.

Essential Oral Functions

The Function of Swallowing (Deglutition)

Swallowing is a series of coordinated muscle movements that moves the bolus from the oral cavity through the esophagus to the stomach.

Speech and Phonetics

The formation of important sounds involves various structures:

• Sounds formed by the lip include m and p.
• Teeth are important in saying s.
• The tongue and palate are essential in forming d.
• The tongue touches the maxillary incisors to form th.
• The lower lip touches the maxillary incisors to form f and v.

The Periodontium

Definition and Components

The periodontium is defined as those tissues supporting and investing the tooth. It consists of the following components:

• Cementum
• Periodontal Ligament (PDL)
• Bone lining the alveolus
• Part of the gingiva facing the tooth

Functions of the Periodontal Ligament (PDL)

• Support: The PDL supports the teeth in their socket.
• Masticatory Load: The PDL permits teeth to withstand the considerable forces of mastication.
• Sensory: The PDL is supplied by abundant receptors and nerves that sense movement when teeth are in function.

Principal Fiber Groups of the PDL

1. The Alveolar Crest Group: These fibers are attached to the cementum just below the cementoenamel junction.
2. The Horizontal Group: These fibers are just apical to the alveolar crest fibers and run at right angles to the long axis of the tooth.
3. The Oblique Group: They are the most numerous fibers in the PDL, running from the cementum in an oblique direction.
4. The Apical Group: These fibers radiate from the cementum around the apex of the root to the bone.
5. The Interradicular Group: Found only in multi-rooted teeth, running from the cementum into the bone forming the crest of the interradicular septum.
6. Sharpey’s Fibers: At each end, all the principal fibers of the PDL are embedded in the cementum or the bone.