📖 Prosthodontics
Complete Denture Occlusion
ProsthodonticsComplete Denture Occlusion
Complete denture occlusion is a critical aspect of prosthodontics, as it affects the function, stability, and comfort of the dentures. There are three primary types of occlusion used in complete dentures: Balanced Occlusion, Monoplane Occlusion, and Lingualized Occlusion. Each type has its own characteristics and applications.
Types of Complete Denture Occlusion
1. Balanced Occlusion
- Definition: Balanced occlusion is characterized by simultaneous contact of all opposing teeth in centric occlusion, providing stability and even distribution of occlusal forces.
- Key Features:
- Three-Point Contact: While a three-point contact (one anterior and two posterior) is a starting point, it is not sufficient for true balanced occlusion. Instead, there should be simultaneous contact of all teeth.
- Minimal Occlusal Balance: For minimal occlusal balance, there should be at least three points of contact on the occlusal plane. The more points of contact, the better the balance.
- Absence in Natural Dentition: Balanced occlusion is not typically found in natural dentition; it is a concept specifically applied to complete dentures to enhance stability during function.
- Importance: This type of occlusion is particularly important for patients with complete dentures, as it helps to minimize tipping and movement of the dentures during chewing and speaking.
2. Monoplane Occlusion
- Definition: Monoplane occlusion involves a flat occlusal plane where the occlusal surfaces of the teeth are arranged in a single plane.
- Key Features:
- Flat Occlusal Plane: The occlusal surfaces are designed to be flat, which simplifies the occlusion and reduces the complexity of the denture design.
- Limited Interference: This type of occlusion minimizes interferences during lateral and protrusive movements, making it easier for patients to adapt to their dentures.
- Applications: Monoplane occlusion is often used in cases where the residual ridge is severely resorbed or in patients with limited jaw movements.
3. Lingualized Occlusion
- Definition: Lingualized occlusion is characterized by the positioning of the maxillary posterior teeth in a way that they occlude with the mandibular posterior teeth, with the buccal cusps of the mandibular teeth being positioned more towards the buccal side.
- Key Features:
- Maxillary Teeth Positioning: The maxillary posterior teeth are positioned more towards the center of the arch, while the mandibular posterior teeth are positioned buccally.
- Functional Balance: This arrangement allows for better functional balance and stability during chewing, as the maxillary teeth provide support to the mandibular teeth.
- Advantages: Lingualized occlusion can enhance the esthetics and function of complete dentures, particularly in patients with a well-defined ridge.
Applegate's Rules
Prosthodontics→ Following rules should be considered to classify partially edentulous
arches, based on Kennedy's classification.
Rule 1:
→ Classification should follow, rather than precede extraction, that might
alter the original classification.
Rule 2:
→ If 3rd molar is missing and not to be replaced, it is not
considered in classification.
Rule 3:
→ If the 3rd molar is present and is to be used as an abutment, it
is considered in classification.
Rule 4:
→ If second molar is missing and is not to be replaced, it is not
considered in classification.
Rule 5:
→ The most posterior edentulous area or areas always determine the
classification.
Rule 6:
→ Edentulous areas other than those, which determine the classification are
referred as modification spaces and are designated by their number.
Rule 7:
→ The extent of modification is not considered, only the number of additional
edentulous areas are taken into consideration (i.e. no. of teeth missing in
modification spaces are not considered, only no. of additional edentulous spaces
are considered).
Rule 8:
→ There can be no modification areas in class IV.
Applegate's Classification for edentulous arches
ProsthodonticsApplegate's Classification is a system used to categorize edentulous
(toothless) arches in preparation for denture construction. The classification
is based on the amount and quality of the remaining alveolar ridge, the
relationship of the ridge to the residual ridges, and the presence of undercuts.
The system is primarily used in the context of complete denture prosthodontics
to determine the best approach for achieving retention, stability, and support
for the dentures.
Applegate's Classification for edentulous arches:
1. Class I: The alveolar ridge has a favorable arch form and sufficient height
and width to provide adequate support for a complete denture without the need
for extensive modifications. This is the ideal scenario for denture
construction.
2. Class II: The alveolar ridge has a favorable arch form but lacks the
necessary height or width to provide adequate support. This may require the use
of denture modifications such as flanges to enhance retention and support.
3. Class III: The ridge lacks both height and width, and there may be undercuts
or excessive resorption. In this case, additional procedures such as ridge
augmentation or the use of implants might be necessary to improve the foundation
for the denture.
4. Class IV: The ridge has an unfavorable arch form, often with significant
resorption, and may require extensive surgical procedures or adjuncts like
implants to achieve a functional and stable denture.
5. Class V: This is the most severe classification where the patient has no
residual alveolar ridge, possibly due to severe resorption, trauma, or surgical
removal. In such cases, the creation of a functional and stable denture may be
highly challenging and might necessitate advanced surgical procedures and/or the
use of alternative prosthetic options like over-dentures with implant support.
It's important to note that this classification is a guide, and individual
patient cases may present with a combination of features from different classes
or may require customized treatment plans based on unique anatomical and
functional requirements.
Anatomy of Maxilary Edentulous Ridge
Prosthodontics
Anatomy of Maxilary Edentulous Ridge
LIMITING STRUCTURES
A) Labial & buccal frenum
- Fibrous band covered by mucous membrane.
- A v-shaped notch (labial notch) should be provided very carefully which should be narrow but deep enough to avoid interference
- Buccal frenum has the attachment of following muscles; levator anguli
- It needs greater clearance on buccal flange of the denture (shallower and wider) than the labial frenum.
B) Labial & buccal vestibule (sulcus)
- Labial sulcus is bounded on one side by the teeth, gingiva and residual alveolar ridge and on the outer side by lips.
- Buccal sulcus extends from buccal frenum anteriorly to the hamular notch posteriorly.
- The size of the vestibule is dependant upon:
i) Contraction of buccinator muscle.
ii) Position of the mandible.
iii) Amount of bone loss in maxilla.
C) Hamular notch
It is depression situated between the maxillary tuberosity and the hamulus of the medial pterygoid plate. It is a soft area of loose connective tissue.
- it houses the disto-lateral termination of the denture.
- Aids in achieving posterior palatal seal.
- Overextension causes soreness.
- Underextension poor retention
D) Posterior palatal seal area (post-dam)
It is a soft tissue area at or beyond the junction of the hard and soft palates on which pressure within physiological limits can be applied by a complete denture to aid in its retention.
Extensions:
1. Anteriorly – Anterior vibrating line
2. Posteriorly – Posterior vibrating line
3. Laterally – 3-4 mm anterolateral to hamular notch
SUPPORTING STRUCTURES
A) Primary stress bearing area / Supporting area
1. Posterior part of the palate
2. Posterolateral part of the residual alveolar ridge
B) Secondary stress bearing area / Supporting area
1. The palatal rugae area
2. Maxillary tuberosity
RELIEF AREAS
A) Incisive papilla
- Midline structure situated behind the central incisors.
- It is an exit point of nasopalatine nerves and vessels.
- It should be relieved if not, the denture will compress the nerve or vessels and lead to necrosis of the distributing areas and paresthesia of anterior palate.
B) Mid-palatine raphe
- Extends from incisive papilla to distal end of hard palate.
- Median suture area covered by thin submucosa
- Relief is to be provided as it is supposed to be the most sensitive part of the palate to pressure
C) Crest of the residual alveolar ridge
D) Fovea palatinae
Few areas like the cuspid eminence , fovea palatinae and torus palatinus may be relieved according to condition required.