Dental Anatomy: Limiting Structures

Study Notes

Limiting Structures

Labial Frenum: A fold of mucous membrane extending from the upper lip to the labial surface of the residual ridge. Can be single or multiple, narrow or broad. Contains no muscle fibers and creates a maxillary labial notch in the impression or denture.
Labial Vestibule: The space between the labial frenum and the buccal frenum. Bounded by the upper lip and residual alveolar ridge. Determines the height of the vestibule. Contains no muscle fibers. The labial flange of a denture fills this space.
Buccal Frenum: A fold of mucous membrane varying in size and shape, extending from the buccal mucous membrane reflection area towards the alveolar ridge. Contains no muscle fibers and creates a maxillary buccal notch in the impression or denture. Affected by orbicularis and buccinator muscles.
Buccal Vestibule: The space distal to the buccal frenum. Bounded by the cheek and residual alveolar ridge. The buccal flange of a denture fills this space. Stability and retention are enhanced when this area is properly filled.
Hamular Notch: A narrow cleft of loose connective tissue located between the maxillary tuberosity and pterygoid hamulus. Serves as the boundary of the posterior border of the maxillary denture.
Vibrating Line: An imaginary line across the palate extending from one hamular notch to the other. Not a well-defined line but rather an area, its direction varying based on the palate's shape.
Fovea Palatinae: Two indentations on each side of the midline formed by mucous gland ducts. Assist in locating the vibrating line, which is the posterior border of the denture.

Supporting Structures

Primary Stress-Bearing Areas:
- Hard Palate (lateral to midline)
- Slopes of the residual alveolar ridge
Secondary Stress-Bearing Areas:
- Rugae Area
- Maxillary Tuberosity
Residual Alveolar Ridge: The bony process remaining after teeth are lost. Covered by mucous membrane, its slope is a primary stress-bearing area.
Maxillary Tuberosity: The area of the alveolar ridge extending distally from the second molar to the hamular notch. Can be oversized, resorbed, or have undercut areas, requiring surgical intervention in some cases.
Rugae Area: Raised areas of dense connective tissue in the anterior one-third of the palate. Aid in vocal sound production and serve as a secondary stress-bearing area.

Relief Areas

Incisive Papilla: A pad of connective tissue lying between the central incisors on the palatal side, overlying the incisive foramen. It houses the nasopalatine nerves and vessels.
Canine Eminence: A round elevation in the corner of the mouth, indicating the location of the canine root. Serves as a guide for arranging maxillary anterior teeth.
Median Palatal Raphe: Extends from the incisive papilla to the distal end of the hard palate, overlying the medial palatal suture. The mucosa is tightly attached and thin, covering a dense bony union. Palatal tori are located here if present.
Zygomatic Process: Located opposite the first molar region, a hard area found in long-term edentulous mouths. Relief may be required to prevent tissue soreness.