• Vermilion Border

Elementary anatomy and

structure of denture bearing area

Shaista Afroz Associate professor

Prosthodontics

Z A Dental college, AMU Aligarh

Lips

• Vermilion Border

– Denture provides lip support

• Affects vermilion border width

Lips

• Philtrum

– Depression below nose

Lips

• Nasolabial Angle

– Angle between columella of nose & philtrum of lip

– Approximately 90 ° as viewed in profile

Lips

• Tissue of the Upper Lip

– Loose tissue of the upper lip

can be gathered between your

thumb and index finger

Cheeks

• Masseter Muscle

– Closing muscle bulges into distal corner of buccal vestibule

– Not active during impression maki ng

Cross Sectional Shape of Masseter

Closed

Masseter Open

Residual Ridges

– After extraction of teeth the alveolar bone is called residual ridge

– “ U ” -shape

– “ V ” -shape

Labial frenum

Buccal frenum

Maxilla-Anatomic Landmarks

Frenum- are folds of mucous membrane and do not contain significant muscle fibers. High frenum attachments will compromise denture retention and may require surgical excision (frenectomy).

Buccal vestibule-when properly filled with the denture flange greatly enhances stability and retention.

Vestibules

Labial vestibule- from labial frenum to buccal frenum

Buccal vestibule- from buccal frenum to distal of maxillary tuberosity

Incisive papilla Canine eminence

Maxilla-Anatomic Landmarks

Canine eminance- This prominent bone provides denture support.

A square arch prevents a denture from rotating and is thus the best for denture stability.

Incisive papilla- Is a pad of fibrous connective tissue overlying the orifice of the nasopalatine canal. Pressure in this area will cause a disruption of blood flow and impingement on the nerve, causing the patient to complain of pain or a burning sensation. The denture

should be relieved over this area.

Maxilla

• Maxillary Tuberosities

– Oversized

– Resorbed

– Undercut

Maxilla

• Maxillary Tuberosities

– Oversized

– Resorbed

– Undercut

Maxilla

• Incisive Papilla

– Landmark for setting of teeth

Maxilla

• “ _Hamular ” _Notch

– Posterior border denture

• “ Soft displaceable tissue ” , for comfort and

retention

Maxilla

• “ _Hamular ” _Notch

– Posterior border denture

• Between the bony

tuberosity and hamulus

Maxilla

• “ _Hamular ” _Notch

– Posterior border denture

• Sometimes posterior to where the depression in the soft tissue appears

• Use the head of your mirror to palpate the

notch & mark with an indelible marker

Maxilla

• Soft Palate

– Vibrating Line

• Critical posterior border dentures

• Junction of movable and immovable

portions of the soft palate

Maxilla

• Glandular Tissue

– Soft displaceable

Maxilla

• Soft Palate

– Fovea Palatine

• Bilateral indentations near midline of the soft palate

• Close to the vibrating line

Maxilla

• Hard Palate

– Median Palatine Raphe (midline palatine suture)

• A bony midline structure

• May require relief when covered by a denture

Maxilla

• Torus Palatinus

– May require removal

Mandible-Anatomic Landmarks

Labial and Buccal frenum- histologically and functionally the same as in the maxilla.

Lingual frenum- overlies the genioglossus muscle, which takes origin from the superior genial spine

Labial flange space- limited inferiorly by the mentallis muscle, internally by the residual ridge and labially by the lip.

Alveolar ridge- is a secondary support area. High rate of resorption when excessive pressure is applied to this area.

Buccal Frenum

Labial Frenum Lingual Frenum Alveolar ridge

Labial flange space

Man dib le - Ana to mic Lan dma rk s

Mental Foramen- the anterior exit of the mandibular canal. In cases of severe residual ridge resorption, the foramen occupies a more superior position and the denture base must be relieved to prevent nerve compression and pain.

External Oblique Line- a ridge of dense bone from the mental foramen, coursing

superiorly and distally to become continuous with the anterior region of the ramus. It serves as the attachment site of the buccinator muscle and an anatomic guide for the lateral termination of the buccal flange of the mandibular denture.

Buccal Shelf- bordered externally by the external oblique line and internally by the slope of the residual ridge. This region of very dense bone is oriented perpendicular to the forces of occlusion and thus becomes a primary stress bearing area in the

mandibular arch.

Mandibular-Anatomic Landmarks

Retromolar Pad- pear shaped area containing glandular tissue, loose areolar connective tissue, the lower margin of the pterygomandibular raphe, fibers of the buccinator and superior constrictor muscles, along with fibers from the temporal tendon. Primary support area of the

mandibular denture.

Masseter Groove- the action of the masseter muscle reflects the

buccinator muscle in a superior and medial direction. The distobuccal flange of the denture should be contoured to allow freedom for this

action otherwise the denture will be displaced or the pt. will experience soreness in this area.

Retromolar Pad

Masseter Groove

Suprahyoid Muscles

Function in elevation of the hyoid bone and the larynx and depression of the mandible.

•Digastric

•Stylohyoid

•Mylohyoid

•Geniohyoid

Mylohyoid muscle- forms the muscular floor of the mouth.

Arises from the mylohyoid ridge of the mandible. Determines the lingual flange extension of the denture.

Mandibular-Anatomic Landmarks

Geniotubercle(Mental Spines)- present on the anterior surface of the mandible and serve as the attachment sites of the genioglossus and geniohyoid muscles. In pts. with severe ridge resorption the genio-

tubercles may cause discomfort if they are exposed to the denture base.

Sublingual Folds- formed by the superior surface of the sublingual glands and theducts of the submandibular glands

Geniotubercles

Sublingual folds

Mandibular-Anatomic Landmarks

Mandibular-Anatomic Landmarks

Retromylohyoid space- lies at the distal end of the alveolingual sulcus.

Bounded medially by the anterior tonsilar pillar, posteriorly by the

retromylohyoid curtain which is formed posteriorly by the superior constrictor muscle, laterally by the mandible and pterygomandibular raphe, anteriorly by the lingual tuberosity of the mandible and inferiorly by the mylohyoid

muscle.***The retromylohyoid space is very important for denture stability and retention.

Retromylohyoid space

Ideal Mandibular Ridge

Well defined retromolar pad

Blunt mylohyoid ridge (to avoid irritation) Deep retromylohyoid space

Low frenum attachments Absence of undercuts

Abundant attached keratinized mucosa Adequate alveolar height

Mandible

• Pear Shaped Pad

– Soft pad containing glandular tissue

– Inverted pear shape, posterior border

– Created from scarring after extractions

Mandible

• Buccal Shelf

– Primary denture bearing area of mandibular denture

– Between height of bridge & external oblique ridge

– Resorbs more slowly

Mandible

• Anterior Border of the Ramus

– Do not extend dentures to ramus

– Discomfort will result

Mandible

• External Oblique Ridge

– Do not extend dentures to this ridge

Mandible

• Mylohyoid Ridge

– Origin of mylohyoid muscle which influences length of lingual flange

– Can be prominent, and/or sharp, requiring

relief

Mandible

• Lingual Tori

– Raised bony structures

– May require relief when covered by a denture

– Thin mucosa can ulcerate easily

Mandible

• Genial Tubercles

– Attachment for the genioglossus muscle – Tubercles may be higher than the ridge

with severe resorption

Frena (singular = frenum)

• Must be relieved to allow movement, without impingement

• If prominent, adequate relief can weaken a denture

• If too much relief, retention is lost

• Check prominence intraorally

Pterygo-Mandibular Raphe

• Connects from the hamulus to the mylohyoid ridge

• When prominent, can cause pain, or loosening

• Requires relief “ groove ” if prominent

Retrozygomal Fossae (Space)

• Palpate zygomatic process in buccal vestibule just buccal to first maxillary molar

• Vestibular space posterior to zygoma

Retrozygomal Fossae (Space)

• Commonly incompletely captured

in preliminary impressions

Coronoid Process

• Place mirror head lateral to tuberosity

• Move mandible to opposite side

• Note binding or pain

• This gives some indication of the width of

the space for flange